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Sample records for anabaena sp pcc

  1. Enhanced resistance to UV-B radiation in Anabaena sp. PCC 7120 (Cyanophyceae) by repeated exposure.

    Science.gov (United States)

    Qin, Hongjie; Li, Dunhai

    2014-07-01

    In natural habitats, organisms especially phytoplankton are not always continuously subjected to ultraviolet-B radiation (UVBR). By simulation of the natural situation, the N2-fixing cyanobacterium Anabaena sp. PCC 7120 was subjected to UV-B exposure and recovery cycles. A series of morphological and physiological changes were observed in Anabaena sp. PCC 7120 under repeated UVBR when compared with controls. Such as the breakage of filaments, intervals between heterocysts, heterocyst frequency, total carbohydrate, and carotenoids were increased, while the nitrogenase activity and photosynthetic activity were inhibited by repeated UVBR; however, these activities could recover when UV-B stress was removed. Unexpectedly, the over-compensatory growth was observed at the end of the second round of exposure and recovery cycle. Our results showed that discontinuous UVBR could increase the growth rate and the tolerance as well as repair capacity of Anabaena sp. PCC 7120. These results indicate that moderate UVBR may increase the growth of cyanobacteria in natural habitats.

  2. All1371 is a polyphosphate-dependent glucokinase in Anabaena sp. PCC 7120.

    Science.gov (United States)

    Klemke, Friederike; Beyer, Gabriele; Sawade, Linda; Saitov, Ali; Korte, Thomas; Maldener, Iris; Lockau, Wolfgang; Nürnberg, Dennis J; Volkmer, Thomas

    2014-12-01

    The polyphosphate glucokinases can phosphorylate glucose to glucose 6-phosphate using polyphosphate as the substrate. ORF all1371 encodes a putative polyphosphate glucokinase in the filamentous heterocyst-forming cyanobacterium Anabaena sp. PCC 7120. Here, ORF all1371 was heterologously expressed in Escherichia coli, and its purified product was characterized. Enzyme activity assays revealed that All1371 is an active polyphosphate glucokinase that can phosphorylate both glucose and mannose in the presence of divalent cations in vitro. Unlike many other polyphosphate glucokinases, for which nucleoside triphosphates (e.g. ATP or GTP) act as phosphoryl group donors, All1371 required polyphosphate to confer its enzymic activity. The enzymic reaction catalysed by All1371 followed classical Michaelis-Menten kinetics, with kcat = 48.2 s(-1) at pH 7.5 and 28 °C and KM = 1.76 µM and 0.118 mM for polyphosphate and glucose, respectively. Its reaction mechanism was identified as a particular multi-substrate mechanism called the 'bi-bi ping-pong mechanism'. Bioinformatic analyses revealed numerous polyphosphate-dependent glucokinases in heterocyst-forming cyanobacteria. Viability of an Anabaena sp. PCC 7120 mutant strain lacking all1371 was impaired under nitrogen-fixing conditions. GFP promoter studies indicate expression of all1371 under combined nitrogen deprivation. All1371 might play a substantial role in Anabaena sp. PCC 7120 under these conditions.

  3. In silico characterization and transcriptomic analysis of nif family genes from Anabaena sp. PCC7120.

    Science.gov (United States)

    Singh, Shilpi; Shrivastava, Alok Kumar

    2017-03-14

    In silico approaches in conjunction with morphology, nitrogenase activity, and qRT-PCR explore the impact of selected abiotic stressor such as arsenic, salt, cadmium, copper, and butachlor on nitrogen fixing (nif family) genes of diazotrophic cyanobacterium Anabaena sp. PCC7120. A total of 19 nif genes are present within the Anabaena genome that is involved in the process of nitrogen fixation. Docking studies revealed the interaction between these nif gene-encoded proteins and the selected abiotic stressors which were further validated through decreased heterocyst frequency, fragmentation of filaments, and downregulation of nitrogenase activity under these stresses indicating towards their toxic impact on nitrogen fixation potential of filamentous cyanobacterium Anabaena sp. PCC7120. Another appealing finding of this study is even though having similar binding energy and similar interacting residues between arsenic/salt and copper/cadmium to nif-encoded proteins, arsenic and cadmium are more toxic than salt and copper for nitrogenase activity of Anabaena which is crucial for growth and yield of rice paddy and soil reclamation.

  4. Methyl viologen responsive proteome dynamics of Anabaena sp. strain PCC7120.

    Science.gov (United States)

    Panda, Bandita; Basu, Bhakti; Rajaram, Hema; Kumar Apte, Shree

    2014-08-01

    A proteomic approach was employed to elucidate the response of an agriculturally important microbe, Anabaena sp. strain PCC7120, to methyl viologen (MV). Exposure to 2 μM MV caused 50% lethality (LD50 ) within 6 h and modified the cellular levels of several proteins. About 31 proteins increased in abundance and 24 proteins decreased in abundance, while 55 proteins showed only a minor change in abundance. Of these, 103 proteins were identified by MS. Levels of proteins involved in ROS detoxification and chaperoning activities were enhanced but that of crucial proteins involved in light and dark reactions of photosynthesis declined or constitutive. The abundance of proteins involved in carbon and energy biogenesis were altered. The study elaborated the oxidative stress defense mechanism deployed by Anabaena, identified carbon metabolism and energy biogenesis as possible major targets of MV sensitivity, and suggested potential biotechnological interventions for improved stress tolerance in Anabaena 7120.

  5. Multiple modes of iron uptake by the filamentous, siderophore-producing cyanobacterium, Anabaena sp. PCC 7120.

    Science.gov (United States)

    Rudolf, Mareike; Kranzler, Chana; Lis, Hagar; Margulis, Ketty; Stevanovic, Mara; Keren, Nir; Schleiff, Enrico

    2015-08-01

    Iron is a member of a small group of nutrients that limits aquatic primary production. Mechanisms for utilizing iron have to be efficient and adapted according to the ecological niche. In respect to iron acquisition cyanobacteria, prokaryotic oxygen evolving photosynthetic organisms can be divided into siderophore- and non-siderophore-producing strains. The results presented in this paper suggest that the situation is far more complex. To understand the bioavailability of different iron substrates and the advantages of various uptake strategies, we examined iron uptake mechanisms in the siderophore-producing cyanobacterium Anabaena sp. PCC 7120. Comparison of the uptake of iron complexed with exogenous (desferrioxamine B, DFB) or to self-secreted (schizokinen) siderophores by Anabaena sp. revealed that uptake of the endogenous produced siderophore complexed to iron is more efficient. In addition, Anabaena sp. is able to take up dissolved, ferric iron hydroxide species (Fe') via a reductive mechanism. Thus, Anabaena sp. exhibits both, siderophore- and non-siderophore-mediated iron uptake. While assimilation of Fe' and FeDFB are not induced by iron starvation, FeSchizokinen uptake rates increase with increasing iron starvation. Consequently, we suggest that Fe' reduction and uptake is advantageous for low-density cultures, while at higher densities siderophore uptake is preferred.

  6. Functional properties of LptA and LptD in Anabaena sp. PCC 7120.

    Science.gov (United States)

    Hsueh, Yi-Ching; Brouwer, Eva-M; Marzi, Julian; Mirus, Oliver; Schleiff, Enrico

    2015-09-01

    Lipopolysaccharides (LPS) are central components of the outer membrane and consist of Lipid A, the core polysaccharide, and the O-antigen. The synthesis of LPS is initiated at the cytosolic face of the cytoplasmic membrane. The subsequent transport to and across the outer membrane involves multiple lipopolysaccharide transport (Lpt) proteins. Among those proteins, the periplasmic-localized LptA and the outer membrane-embedded LptD participate in the last steps of transfer and insertion of LPS into the outer membrane. While the process is described for proteobacterial model systems, not much is known about the machinery in cyanobacteria. We demonstrate that anaLptD (alr1278) of Anabaena sp. PCC 7120 is important for cell wall function and its pore domain shows a Lipid A sensitive cation-selective gating behavior. The N-terminal domain of anaLptD recognizes anaLptA (alr4067), but not ecLptA. Furthermore, anaLptA specifically interacts with the Lipid A from Anabaena sp. PCC 7120 only, while anaLptD binds to Lipid A isolated from Escherichia coli as well. Based on the comparative analysis of proteins from E. coli and Anabaena sp. we discuss the properties of the cyanobacterial Lpt system.

  7. Efficient Gene Induction and Endogenous Gene Repression Systems for the Filamentous Cyanobacterium Anabaena sp. PCC 7120.

    Science.gov (United States)

    Higo, Akiyoshi; Isu, Atsuko; Fukaya, Yuki; Hisabori, Toru

    2016-02-01

    In the last decade, many studies have been conducted to employ genetically engineered cyanobacteria in the production of various metabolites. However, the lack of a strict gene regulation system in cyanobacteria has hampered these attempts. The filamentous cyanobacterium Anabaena sp. PCC 7120 performs both nitrogen and carbon fixation and is, therefore, a good candidate organism for such production. To employ Anabaena cells for this purpose, we intended to develop artificial gene regulation systems to alter the cell metabolic pathways efficiently. We introduced into Anabaena a transcriptional repressor TetR, widely used in diverse organisms, and green fluorescent protein (GFP) as a reporter. We found that anhydrotetracycline (aTc) substantially induced GFP fluorescence in a concentration-dependent manner. By expressing tetR under the nitrate-specific promoter nirA, we successfully reduced the concentration of aTc required for the induction of gfp under nitrogen fixation conditions (to 10% of the concentration needed under nitrate-replete conditions). Further, we succeeded in the overexpression of GFP by depletion of nitrate without the inducer by means of promoter engineering of the nirA promoter. Moreover, we applied these gene regulation systems to a metabolic enzyme in Anabaena and successfully repressed glnA, the gene encoding glutamine synthetase that is essential for nitrogen assimilation in cyanobacteria, by expressing the small antisense RNA for glnA. Consequently, the ammonium production of an ammonium-excreting Anabaena mutant was significantly enhanced. We therefore conclude that the gene regulation systems developed in this study are useful tools for the regulation of metabolic enzymes and will help to increase the production of desired substances in Anabaena.

  8. The Anabaena sp. PCC 7120 Exoproteome: Taking a Peek outside the Box

    Directory of Open Access Journals (Sweden)

    Paulo Oliveira

    2015-01-01

    Full Text Available The interest in examining the subset of proteins present in the extracellular milieu, the exoproteome, has been growing due to novel insights highlighting their role on extracellular matrix organization and biofilm formation, but also on homeostasis and development. The cyanobacterial exoproteome is poorly studied, and the role of cyanobacterial exoproteins on cell wall biogenesis, morphology and even physiology is largely unknown. Here, we present a comprehensive examination of the Anabaena sp. PCC 7120 exoproteome under various growth conditions. Altogether, 139 proteins belonging to 16 different functional categories have been identified. A large fraction (48% of the identified proteins is classified as “hypothetical”, falls into the “other categories” set or presents no similarity to other proteins. The evidence presented here shows that Anabaena sp. PCC 7120 is capable of outer membrane vesicle formation and that these vesicles are likely to contribute to the exoproteome profile. Furthermore, the activity of selected exoproteins associated with oxidative stress has been assessed, suggesting their involvement in redox homeostasis mechanisms in the extracellular space. Finally, we discuss our results in light of other cyanobacterial exoproteome studies and focus on the potential of exploring cyanobacteria as cell factories to produce and secrete selected proteins.

  9. Characterization of a DUF820 family protein Alr3200 of the cyanobacterium Anabaena sp. strain PCC7120

    Indian Academy of Sciences (India)

    PRASHANTH S RAGHAVAN; GAGAN D GUPTA; HEMA RAJARAM; VINAY KUMAR

    2016-12-01

    The hypothetical protein ‘Alr3200’ of Anabaena sp. strain PCC7120 is highly conserved among cyanobacterialspecies. It is a member of the DUF820 (Domain of Unknown Function) protein family, and is predicted to have aDNase domain. Biochemical analysis revealed a Mg(II)-dependent DNase activity for Alr3200 with a specific activityof 8.62×104 Kunitz Units (KU) mg−1 protein. Circular dichroism analysis predicted Alr3200 to have ~40% β-strandsand ~9% α-helical structures. Anabaena PCC7120 inherently expressed Alr3200 at very low levels, and its overexpressionhad no significant effect on growth of Anabaena under control conditions. However, Analr3200+, therecombinant Anabaena strain overexpressing Alr3200, exhibited zero survival upon exposure to 6 kGy of γ-radiation,which is the LD50 for wild type Anabaena PCC7120 as well as the vector control recombinant strain, AnpAM.Comparative analysis of the two recombinant Anabaena strains suggested that it is not the accumulated Alr3200 perse, but its possible interactions with the radiation-induced unidentified DNA repair proteins of Anabaena, whichhampers DNA repair resulting in radiosensitivity.

  10. Mixotrophic Cultures of Anabaena sp. PCC7120%鱼腥藻 Anabaena sp. PCC7120的混合营养生长

    Institute of Scientific and Technical Information of China (English)

    喻国策; 辛晓峰; 蔡昭铃; 施定基; 欧阳藩

    2000-01-01

    在高光强为160 μE/(m2.s)、低光强为16 μE/(m2.s)、葡萄糖浓度030g/L范围内,进行了鱼腥藻 Anabaena sp. PCC7120的摇瓶光自养和混合营养培养.在高光强下最大藻细胞密度(0.923.1g/L)明显高于低光强(0.110.58g/L),而且高光强使混合营养培养的对数期缩短.在不同光强下,葡萄糖浓度在018g/L范围内提高显著促进了细胞的生长,在1830g/L范围内变化对细胞生长不再有更大的影响.高光强促进了藻细胞对葡萄糖的利用.在高光强下随着葡萄糖浓度的提高,细胞得率逐渐变小.

  11. Paired cloning vectors for complementation of mutations in the cyanobacterium Anabaena sp. strain PCC 7120

    Energy Technology Data Exchange (ETDEWEB)

    Wolk, C. Peter Wolk [Michigan State University, East Lansing; Fan, Qing [Northwestern University, Evanston; Zhou, Ruanbao [Anhui Normal University, People' s Republic of China; Huang, Guocun [University of Texas Southwestern Medical; Lechno-Yossef, Sigal [Michigan State University, East Lansing; Kuritz, Tanya [ORNL; Wojciuch, Elizabeth [Michigan State University, East Lansing

    2007-01-01

    The clones generated in a sequencing project represent a resource for subsequent analysis of the organism whose genome has been sequenced. We describe an interrelated group of cloning vectors that either integrate into the genome or replicate, and that enhance the utility, for developmental and other studies, of the clones used to determine the genomic sequence of the cyanobacterium, Anabaena sp. strain PCC 7120. One integrating vector is a mobilizable BAC vector that was used both to generate bridging clones and to complement transposon mutations. Upon addition of a cassette that permits mobilization and selection, pUC-based sequencing clones can also integrate into the genome and thereupon complement transposon mutations. The replicating vectors are based on cyanobacterial plasmid pDU1, whose sequence we report, and on broad-host-range plasmid RSF1010. The RSF1010- and pDU1-based vectors provide the opportunity to express different genes from either cell-type-specific or -generalist promoters, simultaneously from different plasmids in the same cyanobacterial cells. We show that pDU1 ORF4 and its upstream region play an essential role in the replication and copy number of pDU1, and that ORFs alr2887 and alr3546 (hetF{sub A}) of Anabaena sp. are required specifically for fixation of dinitrogen under oxic conditions.

  12. Outer membrane proteins induced by iron deficiency in Anabaena sp.PCC 7120

    Institute of Scientific and Technical Information of China (English)

    Yanling Dong; Xudong Xu

    2009-01-01

    Iron deficiency can induce cyanobacteria to synthesize siderophore receptor proteins on the outer membrane to enhance the uptake of iron. In this study, an outer membrane of high purity was prepared from Anabaena sp. PCC 7120 based on aqueous polymer two-phase partitioning and discontinuous sucrose density ultra-centrifugation, and the induction of outer membrane proteins by iron deficiency was investigated using 2-D gel electrophoresis. At least five outer membrane proteins were newly synthesized or significantly up-regulated in cells transferred to iron-deficient conditions, which were all identified to be siderophore receptor proteins according to MALDI-TOF-MS analyses. Bacterial luciferase reporter genes luxAB were employed to monitor the transcription of the encoding genes. The genes were induced by iron deficiency at the transcriptional level in different responsive modes. Luciferase activity expressed from an iron-regulated promoter may be used as a bioreporter for utilizable iron in natural water samples.

  13. The regulation of HanA during heterocyst development in cyanobacterium Anabaena sp. PCC 7120.

    Science.gov (United States)

    Lu, Jing-Jing; Shi, Lei; Chen, Wen-Li; Wang, Li

    2014-10-01

    In response to deprivation of combined nitrogen, the filamentous cyanobacterium Anabaena sp. strain PCC 7120 develops heterocyst, which is specifically involved in the nitrogen fixation. In this study, we focused on the regulation of HanA, a histone-like protein, in heterocyst development. Electrophoretic mobility shift assay results showed that NtcA, a global nitrogen regulator necessary for heterocyst differentiation, could bind to two NtcA-binding motifs in the hanA promoter region. qPCR results also showed that NtcA may regulate the expression of hanA. By using the hanA promoter-controlled gfp as a reporter gene and performing western blot we found that the amount of HanA in mature heterocysts was decreased gradually.

  14. Nitrate assimilation gene cluster from the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120.

    Science.gov (United States)

    Frías, J E; Flores, E; Herrero, A

    1997-01-01

    A region of the genome of the filamentous, nitrogen-fixing, heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 that contains a cluster of genes involved in nitrate assimilation has been identified. The genes nir, encoding nitrite reductase, and nrtABC, encoding elements of a nitrate permease, have been cloned. Insertion of a gene cassette into the nir-nrtA region impaired expression of narB, the nitrate reductase structural gene which together with nrtD is found downstream from nrtC in the gene cluster. This indicates that the nir-nrtABCD-narB genes are cotranscribed, thus constituting an operon. Expression of the nir operon in strain PCC 7120 is subjected to ammonium-promoted repression and takes place from an NtcA-activated promoter located 460 bp upstream from the start of the nir gene. In the absence of ammonium, cellular levels of the products of the nir operon are higher in the presence of nitrate than in the absence of combined nitrogen.

  15. Lipopolysaccharide dependence of cyanophage sensitivity and aerobic nitrogen fixation in Anabaena sp. strain PCC 7120.

    Science.gov (United States)

    Xu, X; Khudyakov, I; Wolk, C P

    1997-05-01

    Fox- mutants of Anabaena sp. strain PCC 7120 are unable to fix dinitrogen in the presence of oxygen. A fragment of the DNA of Anabaena sp. was cloned by complementation of a spontaneous Fox-, cyanophage-resistant mutant, R56, and characterized. Random insertion of transposon Tn5 delimited the complementing DNA to a 0.6-kb portion of the cloned fragment. Sequencing of this region and flanking DNA showed one complete open reading frame (ORF) similar to the gene rfbP (undecaprenyl-phosphate galactosephosphotransferase) and two partial ORFs similar to genes rfbD (GDP-D-mannose dehydratase) and rfbZ (first mannosyl transferase), all of which are active in the synthesis of the O antigen unit of the lipopolysaccharide (LPS) component of the outer membrane of gram-negative bacteria. In a transposon (Tn5-1087b)-induced, Fox-, cyanophage-resistant mutant, B14, the transposon was found within the same rfbP-like ORF. The three ORFs were insertionally inactivated with the omega cassette (P. Prentki and H. M. Krisch, Gene 29:303-313, 1984) or with Tn5::omega. Only the insertions in the rfbZ- and rfbP-like ORFs led to resistance to cyanophages A-1(L) and A-4(L) and to a Fox- phenotype. Electrophoretic analysis showed that interruption of the rfbZ- and rfbP-like ORFs resulted in a change in or loss of the characteristic pattern of the lengths of the LPS, whereas interruption of the rfbD-like ORF merely changed the distribution of the lengths of the LPS to one with a greater prevalence of low molecular weights. According to electron microscopy, interruption of the rfbP-like ORF may have led to aberrant deposition of the layers of the heterocyst envelope, resulting in increased leakage of oxygen into the heterocyst. The results suggest that modified LPS may prevent cyanophage infection of Anabaena sp. vegetative cells and the formation of a functional heterocyst envelope.

  16. 鱼腥藻PCC7120ntcA基因研究进展%Research Progress of ntcA Gene in Anabaena sp.PCC 7120

    Institute of Scientific and Technical Information of China (English)

    蔡雁; 高宏

    2012-01-01

    Since the first identification of the coded protein by ntcA gene in Anabaena sp. PCC 7120 in 1990, the study had obtained a great achievement, the research achievements mainly focused on the structure, function and mechanism of ntcA gene and its encoding proteins, which provided clues for comprehensively knowing nitrogen metabolism and heterocyst differentiation in Anabaena sp. PCC 7120. The study reviewed the advances of ntcA gene in Anabaena sp. PCC 7120 from the following four aspects: the structure of ntcA gene, the function of its encoding proteins, the mechanism of action and the action range.%自1990年鱼腥藻PCC 7120中ntcA基因编码的蛋白被发现和鉴定以来,对其研究已取得一系列重要进展,其研究成果主要集中于ntcA基因及其编码蛋白的结构、功能及作用机制等方面,为更全面的了解鱼腥藻PCC 7120中的氮代谢和异形胞分化提供了线索.该研究分别从ntcA基因结构、其编码蛋白的功能、作用机制及作用范围等4个方面对鱼腥藻PCC 7120 ntcA基因的研究进展进行了简要综述.

  17. Expanding the direct HetR regulon in Anabaena sp. strain PCC 7120.

    Science.gov (United States)

    Videau, Patrick; Ni, Shuisong; Rivers, Orion S; Ushijima, Blake; Feldmann, Erik A; Cozy, Loralyn M; Kennedy, Michael A; Callahan, Sean M

    2014-03-01

    In response to a lack of environmental combined nitrogen, the filamentous cyanobacterium Anabaena sp. strain PCC 7120 differentiates nitrogen-fixing heterocyst cells in a periodic pattern. HetR is a transcription factor that coordinates the regulation of this developmental program. An inverted repeat-containing sequence in the hepA promoter required for proheterocyst-specific transcription was identified based on sequence similarity to a previously characterized binding site for HetR in the promoter of hetP. The binding affinity of HetR for the hepA site is roughly an order of magnitude lower than that for the hetP binding site. A BLAST search of the Anabaena genome identified 166 hepA-like sites that occur as single or tandem sites (two binding sites separated by 13 bp). The vast majority of these sites are present in predicted intergenic regions. HetR bound five representative single binding sites in vitro, and binding was abrogated by transversions in the binding sites that conserved the inverted repeat nature of the sites. Binding to four representative tandem sites was not observed. Transcriptional fusions of the green fluorescent protein gene gfp with putative promoter regions associated with the representative binding sites indicated that HetR could function as either an activator or repressor and that activation was cell-type specific. Taken together, we have expanded the direct HetR regulon and propose a model in which three categories of HetR binding sites, based on binding affinity and nucleotide sequence, contribute to three of the four phases of differentiation.

  18. Role of the all1549 (ana-rsh) gene, a relA/spoT homolog, of the Cyanobacterium Anabaena sp. PCC7120.

    Science.gov (United States)

    Ning, Degang; Qian, Yaru; Miao, Xiaogang; Wen, Chongwei

    2011-06-01

    The role of a single relA/spoT homolog all1549 (designated hereafter as ana-rsh) of the cyanobacterium Anabaena sp. PCC7120 was investigated. The complementation test in Escherichia coli showed that the protein encoded by ana-rsh possesses guanosine tetraphosphate (p)ppGpp-synthase/hydrolase activity. Under laboratory growth conditions, a low level of ppGpp was detected in Anabaena sp. PCC7120 and the loss of ana-rsh was lethal. Amino acid starvation induced ppGpp accumulation to an appropriate level, and nitrogen deficiency did not alter the ppGpp concentration in Anabaena cells. These data suggest that ana-rsh is required for cell viability under normal growth conditions and involved in the (p)ppGpp-related stringent response to amino acid deprivation, but not related to heterocyst formation and nitrogen fixation of Anabaena sp. PCC7120.

  19. HesF, an exoprotein required for filament adhesion and aggregation in Anabaena sp. PCC 7120.

    Science.gov (United States)

    Oliveira, Paulo; Pinto, Filipe; Pacheco, Catarina C; Mota, Rita; Tamagnini, Paula

    2015-05-01

    Here, we report on the identification and characterization of a protein (Alr0267) named HesF, found in the extracellular milieu of Anabaena sp. PCC 7120 grown diazotrophically. hesF was found to be highly upregulated upon transition from non-nitrogen-fixing to nitrogen-fixing conditions, and the highest transcript levels were detected towards the end of the heterocyst differentiation process. The hesF promoter drives transcription of the gene in heterocysts only, and both NtcA and HetR are essential for the gene's in vivo activation. An examination of HesF's translocation showed that the secretion system is neither heterocyst-specific nor dependent on nitrogen-fixing conditions. Furthermore, HesF was found to be a type I secretion system substrate, since an HgdD mutant failed to secrete HesF. Several analyses revealed that a HesF minus mutant strain lacks the heterocyst-specific polysaccharide fibrous layer, accumulates high amounts of polysaccharides in the medium and that HesF is essential for the typical aggregation phenotype in diazotrophic conditions. Thus, we propose that HesF is a carbohydrate-binding exoprotein that plays a role in maintaining the heterocyst cell wall structure. A combination of and possibly interaction between HesF and heterocyst-specific polysaccharides seems to be responsible for filament adhesion and culture aggregation in heterocyst-forming cyanobacteria.

  20. Assessment of Anabaena sp. Strain PCC 7120 as a Heterologous Expression Host for Cyanobacterial Natural Products: Production of Lyngbyatoxin A.

    Science.gov (United States)

    Videau, Patrick; Wells, Kaitlyn N; Singh, Arun J; Gerwick, William H; Philmus, Benjamin

    2016-09-16

    Cyanobacteria are well-known producers of natural products of highly varied structure and biological properties. However, the long doubling times, difficulty in establishing genetic methods for marine cyanobacteria, and low compound titers have hindered research into the biosynthesis of their secondary metabolites. While a few attempts to heterologously express cyanobacterial natural products have occurred, the results have been of varied success. Here, we report the first steps in developing the model freshwater cyanobacterium Anabaena sp. strain PCC 7120 (Anabaena 7120) as a general heterologous expression host for cyanobacterial secondary metabolites. We show that Anabaena 7120 can heterologously synthesize lyngbyatoxin A in yields comparable to those of the native producer, Moorea producens, and detail the design and use of replicative plasmids for compound production. We also demonstrate that Anabaena 7120 recognizes promoters from various biosynthetic gene clusters from both free-living and obligate symbiotic marine cyanobacteria. Through simple genetic manipulations, the titer of lyngbyatoxin A can be improved up to 13-fold. The development of Anabaena 7120 as a general heterologous expression host enables investigation of interesting cyanobacterial biosynthetic reactions and genetic engineering of their biosynthetic pathways.

  1. Determination of 2-methylisoborneol and geosmin produced by Streptomyces sp. and Anabaena PCC7120.

    Science.gov (United States)

    Xie, Yuqun; He, Jin; Huang, Jun; Zhang, Jibin; Yu, Ziniu

    2007-08-22

    A new sample preparation and enrichment technique, headspace liquid-phase microextraction (HS-LPME) linked to gas chromatography-mass spectrometry (GC-MS), was developed for the determination of the off-flavor odorants, 2-methylisoborneol and geosmin, produced by Streptomyces sp. and Anabaena PCC7120. Some of the factors that influence the extraction efficiency of HS-LPME, such as the type of extraction solvent, ionic strength of sample solution, and sample agitation rate, were studied and optimized by a single factor test. Other factors, including extraction temperature, extraction time, microdrop volume, and headspace volume were optimized by orthogonal array design. Extraction of 2-methylisoborneol and geosmin was conducted by exposing 2.5 microL of 1-hexanol for 9 min at 50 degrees C in the headspace of a 20 mL vial with a 10 mL of sample solution saturated by NaCl and stirred at 800 rpm. The developed protocol demonstrated good repeatability (relative standard deviations (RSDs) 0.999), and low limits of detection (LODs) for 2-methylisoborneol and geosmin (0.05 ng/L for both analytes). Subsequently, the method was successfully applied to extract the analytes in bacterial cultures with high recoveries (from 94% to 98%). Compared with headspace solid-phase microextraction (HS-SPME), HS-LPME demonstrates better linearity, precision, and recovery. Importantly, the sensitivity is about 1 order of magnitude higher than that of most HS-SPME. The results showed that HS-LPME coupled with GC-MS is a simple, convenient, rapid, sensitive, and effective method for the qualitative and quantitative analysis of 2-methylisoborneol and geosmin.

  2. Identification and characterization of UDP-glucose pyrophosphorylase in cyanobacteria Anabaena sp. PCC 7120.

    Science.gov (United States)

    Kawano, Yusuke; Sekine, Midori; Ihara, Masaki

    2014-05-01

    Exopolysaccharides produced by photosynthetic cyanobacteria have received considerable attention in recent years for their potential applications in the production of renewable biofuels. Particularly, cyanobacterial cellulose is one of the most promising products because it is extracellularly secreted as a non-crystalline form, which can be easily harvested from the media and converted into glucose units. In cyanobacteria, the production of UDP-glucose, the cellulose precursor, is a key step in the cellulose synthesis pathway. UDP-glucose is synthesized from UTP and glucose-1-phosphate (Glc-1P) by UDP-glucose pyrophosphorylase (UGPase), but this pathway in cyanobacteria has not been well characterized. Therefore, to elucidate the overall cellulose biosynthesis pathway in cyanobacteria, we studied the putative UGPase All3274 and seven other putative NDP-sugar pyrophosphorylases (NSPases), All4645, Alr2825, Alr4491, Alr0188, Alr3400, Alr2361, and Alr3921 of Anabaena sp. PCC 7120. Assays using the purified recombinant proteins revealed that All3274 exhibited UGPase activity, All4645, Alr2825, Alr4491, Alr0188, and Alr3921 exhibited pyrophosphorylase activities on ADP-glucose, CDP-glucose, dTDP-glucose, GDP-mannose, and UDP-N-acetylglucosamine, respectively. Further characterization of All3274 revealed that the kcat for UDP-glucose formation was one or two orders lower than those of other known UGPases. The activity and dimerization tendency of All3274 increased at higher enzyme concentrations, implying catalytic activation by dimerization. However, most interestingly, All3274 dimerization was inhibited by UTP and Glc-1P, but not by UDP-glucose. This study presents the first in vitro characterization of a cyanobacterial UGPase, and provides insights into biotechnological attempts to utilize the photosynthetic production of cellulose from cyanobacteria.

  3. Characterization of three putative xylulose 5-phosphate/fructose 6-phosphate phosphoketolases in the cyanobacterium Anabaena sp. PCC 7120.

    Science.gov (United States)

    Moriyama, Takashi; Tajima, Naoyuki; Sekine, Kohsuke; Sato, Naoki

    2015-01-01

    Xylulose 5-phosphate/fructose 6-phosphate phosphoketolase (Xfp) is a key enzyme in the central carbohydrate metabolism in heterofermentative bacteria, in which enzymatic property of Xfps is well characterized. This is not the case in other microbes. The cyanobacterium Anabaena sp. PCC 7120 possesses three putative genes encoding Xfp, all1483, all2567, and alr1850. We purified three putative Xfps as recombinant proteins. The results of gel filtration indicated that these proteins form homomultimer complex. All1483 and All2567 showed phosphoketolase activity, whereas Alr1850 did not show the activity. Kinetic analyses demonstrated that substrates, fructose 6-phosphate and inorganic phosphate, are cooperatively bound to enzymes positively and negatively, respectively.

  4. Amino Acid Transporters and Release of Hydrophobic Amino Acids in the Heterocyst-Forming Cyanobacterium Anabaena sp. Strain PCC 7120

    Directory of Open Access Journals (Sweden)

    Rafael Pernil

    2015-04-01

    Full Text Available Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that can use inorganic compounds such as nitrate or ammonium as nitrogen sources. In the absence of combined nitrogen, it can fix N2 in differentiated cells called heterocysts. Anabaena also shows substantial activities of amino acid uptake, and three ABC-type transporters for amino acids have been previously characterized. Seven new loci encoding predicted amino acid transporters were identified in the Anabaena genomic sequence and inactivated. Two of them were involved in amino acid uptake. Locus alr2535-alr2541 encodes the elements of a hydrophobic amino acid ABC-type transporter that is mainly involved in the uptake of glycine. ORF all0342 encodes a putative transporter from the dicarboxylate/amino acid:cation symporter (DAACS family whose inactivation resulted in an increased uptake of a broad range of amino acids. An assay to study amino acid release from Anabaena filaments to the external medium was set up. Net release of the alanine analogue α-aminoisobutyric acid (AIB was observed when transport system N-I (a hydrophobic amino acid ABC-type transporter was engaged in the uptake of a specific substrate. The rate of AIB release was directly proportional to the intracellular AIB concentration, suggesting leakage from the cells by diffusion.

  5. Characterization of two naturally truncated, Ssb-like proteins from the nitrogen-fixing cyanobacterium, Anabaena sp. PCC7120.

    Science.gov (United States)

    Kirti, Anurag; Rajaram, Hema; Apte, Shree Kumar

    2013-11-01

    Single-stranded (ss) DNA-binding (Ssb) proteins are vital for all DNA metabolic processes and are characterized by an N-terminal OB-fold followed by P/G-rich spacer region and a C-terminal tail. In the genome of the heterocystous, nitrogen-fixing cyanobacterium, Anabaena sp. strain PCC 7120, two genes alr0088 and alr7579 are annotated as ssb, but the corresponding proteins have only the N-terminal OB-fold and no P/G-rich region or acidic tail, thereby rendering them unable to interact with genome maintenance proteins. Both the proteins were expressed under normal growth conditions in Anabaena PCC7120 and regulated differentially under abiotic stresses which induce DNA damage, indicating that these are functional genes. Constitutive overexpression of Alr0088 in Anabaena enhanced the tolerance to DNA-damaging stresses which caused formation of DNA adducts such as UV and MitomycinC, but significantly decreased the tolerance to γ-irradiation, which causes single- and double-stranded DNA breaks. On the other hand, overexpression of Alr7579 had no significant effect on normal growth or stress tolerance of Anabaena. Thus, of the two truncated Ssb-like proteins, Alr0088 may be involved in protection of ssDNA from damage, but due to the absence of acidic tail, it may not aid in repair of damaged DNA. These two proteins are present across cyanobacterial genera and unique to them. These initial studies pave the way to the understanding of DNA repair in cyanobacteria, which is not very well documented.

  6. A Comprehensively Curated Genome-Scale Two-Cell Model for the Heterocystous Cyanobacterium Anabaena sp. PCC 7120.

    Science.gov (United States)

    Malatinszky, David; Steuer, Ralf; Jones, Patrik R

    2017-01-01

    Anabaena sp. PCC 7120 is a nitrogen-fixing filamentous cyanobacterium. Under nitrogen-limiting conditions, a fraction of the vegetative cells in each filament terminally differentiate to nongrowing heterocysts. Heterocysts are metabolically and structurally specialized to enable O2-sensitive nitrogen fixation. The functionality of the filament, as an association of vegetative cells and heterocysts, is postulated to depend on metabolic exchange of electrons, carbon, and fixed nitrogen. In this study, we compile and evaluate a comprehensive curated stoichiometric model of this two-cell system, with the objective function based on the growth of the filament under diazotrophic conditions. The predicted growth rate under nitrogen-replete and -deplete conditions, as well as the effect of external carbon and nitrogen sources, was thereafter verified. Furthermore, the model was utilized to comprehensively evaluate the optimality of putative metabolic exchange reactions between heterocysts and vegetative cells. The model suggested that optimal growth requires at least four exchange metabolites. Several combinations of exchange metabolites resulted in predicted growth rates that are higher than growth rates achieved by only considering exchange of metabolites previously suggested in the literature. The curated model of the metabolic network of Anabaena sp. PCC 7120 enhances our ability to understand the metabolic organization of multicellular cyanobacteria and provides a platform for further study and engineering of their metabolism.

  7. Alr5068, a Low-Molecular-Weight protein tyrosine phosphatase, is involved in formation of the heterocysts polysaccharide layer in the cyanobacterium Anabaena sp. PCC 7120.

    Science.gov (United States)

    Tan, Hui; Wan, Shuang; Liu, Pi-Qiong; Wang, Li; Zhang, Cheng-Cai; Chen, Wen-Li

    2013-10-01

    The filamentous cyanobacterium Anabaena sp. PCC 7120 forms nitrogen-fixing heterocysts after deprivation of combined nitrogen. Under such conditions, vegetative cells provide heterocysts with photosynthate and receive fixed nitrogen from the latter. Heterocyst envelope contains a glycolipid layer and a polysaccharide layer to restrict the diffusion of oxygen into heterocysts. Low-Molecular-Weight protein tyrosine phosphatases (LMW-PTPs) are involved in the biosynthesis of exopolysaccharides in bacteria. Alr5068, a protein from Anabaena sp. PCC 7120, shows significant sequence similarity with LMW-PTPs. In this study we characterized the enzymatic properties of Alr5068 and showed that it can dephosphorylate several autophosphorylated tyrosine kinases (Alr2856, Alr3059 and All4432) of Anabaena sp. PCC 7120 in vitro. Several conserved residues among LMW-PTPs are shown to be essential for the phosphatase activity of Alr5068. Overexpression of alr5068 results in a strain unable to survive under diazotrophic conditions, with the formation of morphologically mature heterocysts detached from the filaments. Overexpression of an alr5068 allele that lost phosphatase activity led to the formation of heterocyst with an impaired polysaccharide layer. The alr5068 gene was upregulated after nitrogen step-down and its mutation affected the expression of hepA and hepC, two genes necessary for the formation of the heterocyst envelope polysaccharide (HEP) layer. Our results suggest that Alr5068 is associated with the production of HEP in Anabaena sp. PCC 7120.

  8. 具异型胞蓝细菌Anabaena sp. PCC 71 20 质膜和%Isolation of Plasma and Thylakoid Membranes from the Heterocystous Cyanobacterium Anabaena sp. PCC 7120

    Institute of Scientific and Technical Information of China (English)

    李斌; 徐冬一; 赵进东

    2001-01-01

    利用水溶性多聚体双相法分离蓝细菌Anabaena sp. PCC 7120质膜和类囊体膜两种膜系统.吸收光谱分析表明,质膜相和类囊体膜相的主要色素分别为类胡萝卜素和叶绿素.SDS_ 凝胶电泳显示这两种膜系统蛋白组成有很大差别.这种分离方法容易操作,对研究蓝细菌的膜蛋白和膜脂非常有用.

  9. 碳氮源对转基因鱼腥藻Anabaena sp.PCC7120培养的影响%Effects of carbon and nitrogen sources on the culture of recombinant Anabaena sp. PCC7120

    Institute of Scientific and Technical Information of China (English)

    刘志伟; 郭勇; 张晨

    2001-01-01

    对碳源、氮源种类和用量对转rhTNF-α基因鱼腥藻7120( Anabaena sp. PCC7120)培养的影响进行了研究,发现最适碳源为蔗糖,最适氮源为NaNO3,最佳用量分别为9 g/L和2.25 g/L,此时生物量远高于自养方式,达2.52g/L,比相同条件下在BG-11培养基培养高71.66%,TNF-α表达量为16%~22%,生物活性为105U/mg.

  10. Requirement of Fra proteins for communication channels between cells in the filamentous nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120.

    Science.gov (United States)

    Omairi-Nasser, Amin; Mariscal, Vicente; Austin, Jotham R; Haselkorn, Robert

    2015-08-11

    The filamentous nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120 differentiates specialized cells, heterocysts, that fix atmospheric nitrogen and transfer the fixed nitrogen to adjacent vegetative cells. Reciprocally, vegetative cells transfer fixed carbon to heterocysts. Several routes have been described for metabolite exchange within the filament, one of which involves communicating channels that penetrate the septum between adjacent cells. Several fra gene mutants were isolated 25 y ago on the basis of their phenotypes: inability to fix nitrogen and fragmentation of filaments upon transfer from N+ to N- media. Cryopreservation combined with electron tomography were used to investigate the role of three fra gene products in channel formation. FraC and FraG are clearly involved in channel formation, whereas FraD has a minor part. Additionally, FraG was located close to the cytoplasmic membrane and in the heterocyst neck, using immunogold labeling with antibody raised to the N-terminal domain of the FraG protein.

  11. A single gene all3940 (Dps) overexpression in Anabaena sp. PCC 7120 confers multiple abiotic stress tolerance via proteomic alterations.

    Science.gov (United States)

    Narayan, Om Prakash; Kumari, Nidhi; Bhargava, Poonam; Rajaram, Hema; Rai, Lal Chand

    2016-01-01

    DNA-binding proteins (Dps) induced during starvation play an important role in gene regulation and maintaining homeostasis in bacteria. The nitrogen-fixing cyanobacterium, Anabaena PCC7120, has four genes annotated as coding for Dps; however, the information on their physiological roles is limiting. One of the genes coding for Dps, 'all3940' was found to be induced under different abiotic stresses in Anabaena and upon overexpression enhanced the tolerance of Anabaena to a multitude of stresses, which included salinity, heat, heavy metals, pesticide, and nutrient starvation. On the other hand, mutation in the gene resulted in decreased growth of Anabaena. The modulation in the levels of All3940 in Anabaena, achieved either by overexpression of the protein or mutation of the gene, resulted in changes in the proteome, which correlated well with the physiological changes observed. Proteins required for varied physiological activities, such as photosynthesis, carbon-metabolism, oxidative stress alleviation, exhibited change in protein profile upon modulation of All3940 levels in Anabaena. This suggested a direct or an indirect effect of All3940 on the expression of the above stress-responsive proteins, thereby enhancing tolerance in Anabaena PCC7120. Thus, All3940, though categorized as a Dps, is possibly a general stress protein having a global role in regulating tolerance to multitude of stresses in Anabaena.

  12. ppGpp metabolism is involved in heterocyst development in the cyanobacterium Anabaena sp. strain PCC 7120.

    Science.gov (United States)

    Zhang, Shao-Ran; Lin, Gui-Ming; Chen, Wen-Li; Wang, Li; Zhang, Cheng-Cai

    2013-10-01

    When deprived of a combined-nitrogen source in the growth medium, the filamentous cyanobacterium Anabaena sp. PCC 7120 (Anabaena) can form heterocysts capable of nitrogen fixation. The process of heterocyst differentiation takes about 20 to 24 h, during which extensive metabolic and morphological changes take place. Guanosine tetraphosphate (ppGpp) is the signal of the stringent response that ensures cell survival by adjusting major cellular activities in response to nutrient starvation in bacteria, and ppGpp accumulates at the early stage of heterocyst differentiation (J. Akinyanju, R. J. Smith, FEBS Lett. 107:173-176, 1979; J Akinyanju, R. J. Smith, New Phytol. 105:117-122, 1987). Here we show that all1549 (here designated relana) in Anabaena, homologous to relA/spoT, is upregulated in response to nitrogen deprivation and predominantly localized in vegetative cells. The disruption of relana strongly affects the synthesis of ppGpp, and the resulting mutant, all1549Ωsp/sm, fails to form heterocysts and to grow in the absence of a combined-nitrogen source. This phenotype can be complemented by a wild-type copy of relana. Although the upregulation of hetR is affected in the mutant, ectopic overexpression of hetR cannot rescue the phenotype. However, we found that the mutant rapidly loses its viability, within a time window of 3 to 6 h, following the deprivation of combined nitrogen. We propose that ppGpp plays a major role in rebalancing the metabolic activities of the cells in the absence of the nitrogen source supply and that this regulation is necessary for filament survival and consequently for the success of heterocyst differentiation.

  13. In silico analysis and experimental validation of lipoprotein and novel Tat signal peptides processing in Anabaena sp. PCC7120.

    Science.gov (United States)

    Kumari, Sonika; Chaurasia, Akhilesh Kumar

    2015-12-01

    Signal peptide (SP) plays a pivotal role in protein translocation. Lipoprotein- and twin arginine translocase (Tat) dependent signal peptides were studied in All3087, a homolog of competence protein of Synechocystis PCC6803 and in two putative alkaline phosphatases (ALPs, Alr2234 and Alr4976), respectively. In silico analysis of All3087 is shown to possess the characteristics feature of competence proteins such as helix-hairpin-helix, N and C-terminal HKD endonuclease domain, calcium binding domain and N-terminal lipoprotein signal peptide. The SP recognition-cleavage site in All3087 was predicted (AIA-AC) using SignalP while further in-depth analysis using Pred-Lipo and WebLogo analysis for consensus sequence showed it as IAA-C. Activities of putative ALPs were confirmed by heterologous overexpression, activity assessment and zymogram analysis. ALP activity in Anabaena remains cell bound in log-phase, but during late log/stationary phase, an enhanced ALP activity was detected in extracellular milieu. The enhancement of ALP activity during stationary phase was not only due to inorganic phosphate limitation but also contributed by the presence of novel bipartite Tat-SP. The Tat signal transported the folded active ALPs to the membrane, followed by anchoring into the membrane and successive cleavage enabling transportation of the ALPs to the extracellular milieu, because of bipartite architecture and processing of transit Tat-SP.

  14. Identification and characterization of the nifV-nifZ-nifT gene region from the filamentous cyanobacterium Anabaena sp. strain PCC 7120.

    OpenAIRE

    1997-01-01

    The nifV and leuA genes, which encode homocitrate synthase and alpha-isopropylmalate synthase, respectively, were cloned from the filamentous cyanobacterium Anabaena sp. strain PCC 7120 by a PCR-based strategy. Since the N-terminal parts of NifV and LeuA from other bacteria are highly similar to each other, a single pair of PCR primers was used to amplify internal fragments of both Anabaena strain 7120 genes. Sequence analysis of cloned PCR products confirmed the presence of two different nif...

  15. Cloning and Characterization of the fecC Gene Necessary for Optimal Growth under Iron-Deficiency Conditions in the Cyanobacterium Anabaena sp.PCC 7120

    Institute of Scientific and Technical Information of China (English)

    XU Wen-liang; LIU Yong-ding; ZHANG Cheng-cai; LI Juan

    2004-01-01

    The fecC gene encoding a putative iron (Ⅲ) dicitrate transporter was cloned from nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120, and inactivated. The mutant grows normally in medium with NO-3, NH+4 or without combined nitrogen. But in iron-deficient medium, the mutant grows slowly. Photosynthetic properties were compared between the mutant and the wild-type strain, the content of photosynthetic pigments in the mutant is lower than that of the wild-type. The results of RT-PCR experiments show that the fecC gene is expressed under iron-deficient conditions, but is not expressed under iron-replete conditions. These results revealed that fecC gene product is required for optimal growth under iron-deficient conditions in Anabaena sp. PCC 7120.

  16. Cryo-imaging of photosystems and phycobilisomes in Anabaena sp. PCC 7120 cells.

    Science.gov (United States)

    Steinbach, Gábor; Schubert, Félix; Kaňa, Radek

    2015-11-01

    Primary photosynthetic reactions take place inside thylakoid membrane where light-to-chemical energy conversion is catalyzed by two pigment-protein complexes, photosystem I (PSI) and photosystem II (PSII). Light absorption in cyanobacteria is increased by pigment-protein supercomplexes--phycobilisomes (PBSs) situated on thylakoid membrane surfaces that transfer excitation energy into both photosystems. We have explored the localization of PSI, PSII and PBSs in thylakoid membrane of native cyanobacteria cell Anabaena sp. 7120 by means of cryogenic confocal microscopy. We have adapted a conventional temperature controlling stage to an Olympus FV1000 confocal microscope. The presence of red shifted emission of chlorophylls from PSI has been confirmed by spectral measurements. Confocal fluorescence images of PSI (in a spectral range 710-750 nm), PSII (in a spectral range 690-705 nm) and PBSs (in a spectral range 650-680 nm) were recorded at low temperature. Co-localization of images showed spatial heterogeneity of PSI, PSII and PBSs over the thylakoid membrane, and three dominant areas were identified: PSI-PSII-PBS supercomplex area, PSII-PBS supercomplex area and PSI area. The observed results were discussed with regard to light-harvesting regulation in cyanobacteria.

  17. Effect of Iron Deficiency on Heterocyst Differentiation and Physiology of the Filamentous Cyanobacterium Anabaena sp. PCC 7120

    Institute of Scientific and Technical Information of China (English)

    Zhang Cheng-cai

    2003-01-01

    The effect of iron deficiency on heterocyst differentiation and some physiological properties of the filamentous cyanobacterium Anabaena sp. PCC 7120was investigated. Under moderate iron limitation conditions, achieved by addition of iron chelator 2,2′-Dipyridyl (<80 μmol/L) led to delayed heterocyst differentiation,no heterocyst differentiation was observed under severe iron limitation conditions,when the concentration of 2,2′-Dipyridyl in the medium was more than 100 μmol/L.It seemed that there are certain iron-regulated genes or operons whose function is to control heterocyst development. In addition, iron deficiency impaired the growth.Low-iron cells had a decrease in the quantities of pigment content (chlorophyll and phycocyanin content), the whole cell in vivo absorbance spectra confirmed the de crease, the protein electrophoretic profiles revealed that iron-deficient cells had less protein bands, with the increase of 2,2′ Dipyridyl , the protein bands was more and more less. And differently, iron deficiency also caused an increase of ROS (Reactive Oxygen Species)and SOD activity, it suggests that iron deficiency led to oxidative stress, which generally occured under high-iron conditions.

  18. Effect of Iron Deficiency on Heterocyst Differentiation and Physiology of the Filamentous Cyanobacterium Anabaena sp. PCC 7120

    Institute of Scientific and Technical Information of China (English)

    XuWen-liang; LiuYong-ding; ZhangCheng-cai

    2003-01-01

    The effect of iron deficiency on heterocyst differentiation and some physiological properties of the filamentous cyanobacterium Anabaena sp. PCC 7120 was investigated. Under moderate iron limitation conditions, achieved by addition of iron chelator 2,2′-Dipyridyl (<80 μmol/L) led to delayed heterocyst differentiation,no heterocyst differentiation was observed under severe iron limitation conditions,when the concentration of 2,2′-Dipyridyl in the medium was more than 100 μmol/L.It seemed that there are certain iron-regulated genes or operons whose function is to control heterocyst development. In addition, iron deficiency impaired the growth.Low-iron cells had a decrease in the quantities of pigment content (chlorophyll and phycocyanin content), the whole cell in vivo absorbance spectra confirmed the decrease, the protein electrophoretic profiles revealed that iron-deficient cells had less protein bands, with the increase of 2,2'-Dipyridyl , the protein bands was more and more less. And differently, iron deficiency also caused an increase of ROS (Reactive Oxygen Species)and SOD activity, it suggests that iron deficiency led to oxidative stress, which uenerallv occured under hiuh-iron conditions.

  19. AhpC (alkyl hydroperoxide reductase) from Anabaena sp. PCC 7120 protects Escherichia coli from multiple abiotic stresses

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Yogesh; Chaurasia, Neha [Molecular Biology Section, Laboratory of Algal Biology, Center of Advanced Study in Botany, Banaras Hindu University, Varanasi-221005 (India); Rai, Lal Chand, E-mail: lcraibhu@gmail.com [Molecular Biology Section, Laboratory of Algal Biology, Center of Advanced Study in Botany, Banaras Hindu University, Varanasi-221005 (India)

    2009-04-17

    Alkyl hydroperoxide reductase (AhpC) is known to detoxify peroxides and reactive sulfur species (RSS). However, the relationship between its expression and combating of abiotic stresses is still not clear. To investigate this relationship, the genes encoding the alkyl hydroperoxide reductase (ahpC) from Anabaena sp. PCC 7120 were introduced into E. coli using pGEX-5X-2 vector and their possible functions against heat, salt, carbofuron, cadmium, copper and UV-B were analyzed. The transformed E. coli cells registered significantly increase in growth than the control cells under temperature (47 {sup o}C), NaCl (6% w/v), carbofuron (0.025 mg ml{sup -1}), CdCl{sub 2} (4 mM), CuCl{sub 2} (1 mM), and UV-B (10 min) exposure. Enhanced expression of ahpC gene as measured by semi-quantitative RT-PCR under aforementioned stresses at different time points demonstrated its role in offering tolerance against multiple abiotic stresses.

  20. The FurA regulon in Anabaena sp. PCC 7120: in silico prediction and experimental validation of novel target genes.

    Science.gov (United States)

    González, Andrés; Angarica, Vladimir Espinosa; Sancho, Javier; Fillat, María F

    2014-04-01

    In the filamentous cyanobacterium Anabaena sp. PCC 7120, the ferric uptake regulator FurA functions as a global transcriptional regulator. Despite several analyses have focused on elucidating the FurA-regulatory network, the number of target genes described for this essential transcription factor is limited to a handful of examples. In this article, we combine an in silico genome-wide predictive approach with experimental determinations to better define the FurA regulon. Predicted FurA-binding sites were identified upstream of 215 genes belonging to diverse functional categories including iron homeostasis, photosynthesis and respiration, heterocyst differentiation, oxidative stress defence and light-dependent signal transduction mechanisms, among others. The probabilistic model proved to be effective at discerning FurA boxes from non-cognate sequences, while subsequent electrophoretic mobility shift assay experiments confirmed the in vitro specific binding of FurA to at least 20 selected predicted targets. Gene-expression analyses further supported the dual role of FurA as transcriptional modulator that can act both as repressor and as activator. In either role, the in vitro affinity of the protein to its target sequences is strongly dependent on metal co-regulator and reducing conditions, suggesting that FurA couples in vivo iron homeostasis and the response to oxidative stress to major physiological processes in cyanobacteria.

  1. Cell envelope components influencing filament length in the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120.

    Science.gov (United States)

    Burnat, Mireia; Schleiff, Enrico; Flores, Enrique

    2014-12-01

    Heterocyst-forming cyanobacteria grow as chains of cells (known as trichomes or filaments) that can be hundreds of cells long. The filament consists of individual cells surrounded by a cytoplasmic membrane and peptidoglycan layers. The cells, however, share a continuous outer membrane, and septal proteins, such as SepJ, are important for cell-cell contact and filament formation. Here, we addressed a possible role of cell envelope components in filamentation, the process of producing and maintaining filaments, in the model cyanobacterium Anabaena sp. strain PCC 7120. We studied filament length and the response of the filaments to mechanical fragmentation in a number of strains with mutations in genes encoding cell envelope components. Previously published peptidoglycan- and outer membrane-related gene mutants and strains with mutations in two genes (all5045 and alr0718) encoding class B penicillin-binding proteins isolated in this work were used. Our results show that filament length is affected in most cell envelope mutants, but the filaments of alr5045 and alr2270 gene mutants were particularly fragmented. All5045 is a dd-transpeptidase involved in peptidoglycan elongation during cell growth, and Alr2270 is an enzyme involved in the biosynthesis of lipid A, a key component of lipopolysaccharide. These results indicate that both components of the cell envelope, the murein sacculus and the outer membrane, influence filamentation. As deduced from the filament fragmentation phenotypes of their mutants, however, none of these elements is as important for filamentation as the septal protein SepJ.

  2. Heterocyst-specific flavodiiron protein Flv3B enables oxic diazotrophic growth of the filamentous cyanobacterium Anabaena sp. PCC 7120.

    Science.gov (United States)

    Ermakova, Maria; Battchikova, Natalia; Richaud, Pierre; Leino, Hannu; Kosourov, Sergey; Isojärvi, Janne; Peltier, Gilles; Flores, Enrique; Cournac, Laurent; Allahverdiyeva, Yagut; Aro, Eva-Mari

    2014-07-29

    Flavodiiron proteins are known to have crucial and specific roles in photoprotection of photosystems I and II in cyanobacteria. The filamentous, heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 contains, besides the four flavodiiron proteins Flv1A, Flv2, Flv3A, and Flv4 present in vegetative cells, two heterocyst-specific flavodiiron proteins, Flv1B and Flv3B. Here, we demonstrate that Flv3B is responsible for light-induced O2 uptake in heterocysts, and that the absence of the Flv3B protein severely compromises the growth of filaments in oxic, but not in microoxic, conditions. It is further demonstrated that Flv3B-mediated photosynthetic O2 uptake has a distinct role in heterocysts which cannot be substituted by respiratory O2 uptake in the protection of nitrogenase from oxidative damage and, thus, in an efficient provision of nitrogen to filaments. In line with this conclusion, the Δflv3B strain has reduced amounts of nitrogenase NifHDK subunits and shows multiple symptoms of nitrogen deficiency in the filaments. The apparent imbalance of cytosolic redox state in Δflv3B heterocysts also has a pronounced influence on the amounts of different transcripts and proteins. Therefore, an O2-related mechanism for control of gene expression is suggested to take place in heterocysts.

  3. HetF and PatA control levels of HetR in Anabaena sp. strain PCC 7120.

    Science.gov (United States)

    Risser, Douglas D; Callahan, Sean M

    2008-12-01

    Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that differentiates heterocysts in response to deprivation of combined nitrogen. A hetF deletion strain lacked heterocysts and had aberrant cell morphology. Site-directed mutagenesis of the predicted active-site histidine and cysteine residues of this putative caspase-hemoglobinase fold protease abolished HetF function, supporting the hypothesis that HetF is a protease. Deletion of patA, which is necessary for the formation of most intercalary heterocysts, or hetF resulted in an increase in HetR protein, and extra copies of hetF on a plasmid functionally bypassed the deletion of patA. A hetR-gfp translational fusion expressed from an inducible promoter demonstrated that hetF-dependent downregulation of HetR levels occurs rapidly in vegetative cells, as well as developing heterocysts. "Mosaic" filaments in which only one cell of a filament had a copy of hetR or hetF indicated that hetF is required for differentiation only in cells that will become heterocysts. hetF was required for transcription from a hetR-dependent transcription start point of the hetR promoter and induction of transcription from the patS promoter. The inverse correlation between the level of HetR protein and transcription from hetR-dependent promoters suggests that the transcriptional activity of HetR is regulated by HetF and PatA.

  4. MreB在鱼腥蓝细菌PCC 7120细胞分裂过程中的功能%Role of MreB on cell division of Anabaena sp.PCC 7120

    Institute of Scientific and Technical Information of China (English)

    李东霞; 王莉; 陈雯莉

    2012-01-01

    为研究Anabaena sp.PCC 7120中的细胞形态决定蛋白MreB的亚细胞定位和功能,构建了由mreB自身启动子驱动的mreB-gfp融合载体,通过接合转移的方法将其转化到野生型Anabaena sp.PCC 7120中,获得绿色荧光蛋白标记的MreB的鱼腥蓝细菌菌株,同时用MreB的抑制剂A22处理菌株.结果显示,MreB的亚细胞定位随着细胞周期的进程而发生变化,A22处理可导致MreB无法正确聚合定位.

  5. Characterization of five putative aspartate aminotransferase genes in the N2-fixing heterocystous cyanobacterium Anabaena sp. strain PCC 7120.

    Science.gov (United States)

    Xu, Xinyi; Gu, Liping; He, Ping; Zhou, Ruanbao

    2015-06-01

    Aspartate and glutamate are two key amino acids used in biosynthesis of many amino acids that play vital role in cellular metabolism. Aspartate aminotransferases (AspATs) are required for channelling nitrogen (N(2)) between Glu and Asp in all life forms. Biochemical and genetic characterization of AspATs have been lacking in N(2)-fixing cyanobacteria. In this report, five putative AspAT genes (alr1039, all2340, alr2765, all4327 and alr4853) were identified in the N(2)-fixing heterocystous cyanobacterium Anabaena sp. PCC 7120. Five recombinant C-terminal hexahistidine-tagged AspATs (AspAT-H(6)) were overexpressed in Escherichia coli and purified to homogeneity. Biochemical analysis demonstrated that these five putative AspATs have authentic AspAT activity in vitro using aspartate as an amino donor. However, the enzymic activities of the five AspATs differed in vitro. Alr4853-H(6) showed the highest AspAT activity, while the enzymic activity for the other four AspATs ranged from 6.5 to 53.7 % activity compared to Alr4853 (100 %). Genetic characterization of the five AspAT genes was also performed by inactivating each individual gene. All of the five AspAT knockout mutants exhibited reduced diazotrophic growth, and alr4853 was further identified to be a Fox gene (requiring fixed N(2) for growth in the presence of oxygen). Four out of five P(aspAT)-gfp transcriptional fusions were constitutively expressed in both diazotrophic and nitrate-dependent growth conditions. Quantitative reverse transcriptase PCR showed that alr4853 expression was increased by 2.3-fold after 24 h of N(2) deprivation. Taken together, these findings add to our understanding of the role of AspATs in N(2)-fixing within heterocystous cyanobacteria.

  6. High radiation and desiccation tolerance of nitrogen-fixing cultures of the cyanobacterium Anabaena sp. strain PCC 7120 emanates from genome/proteome repair capabilities.

    Science.gov (United States)

    Singh, Harinder; Anurag, Kirti; Apte, Shree Kumar

    2013-10-12

    The filamentous nitrogen-fixing cyanobacterium, Anabaena sp. strain PCC 7120 was found to tolerate very high doses of (60)Co-gamma radiation or prolonged desiccation. Post-stress, cells remained intact and revived all the vital functions. A remarkable capacity to repair highly disintegrated genome and recycle the damaged proteome appeared to underlie such high radioresistance and desiccation tolerance. The close similarity observed between the cellular response to irradiation or desiccation stress lends strong support to the notion that tolerance to these stresses may involve similar mechanisms.

  7. Cysteine Mutational Studies Provide Insight into a Thiol-Based Redox Switch Mechanism of Metal and DNA Binding in FurA from Anabaena sp. PCC 7120

    OpenAIRE

    Botello-Morte, Laura; Pellicer, Silvia; Sein-Echaluce, Violeta C.; Contreras, Lellys M.; Neira, José Luis; Abián, Olga; Velázquez-Campoy, Adrián; Peleato, María Luisa; Fillat, María F; Bes, María Teresa

    2016-01-01

    Aims: The ferric uptake regulator (Fur) is the main transcriptional regulator of genes involved in iron homeostasis in most prokaryotes. FurA from Anabaena sp. PCC 7120 contains five cysteine residues, four of them arranged in two redox-active CXXC motifs. The protein needs not only metal but also reducing conditions to remain fully active in vitro. Through a mutational study of the cysteine residues present in FurA, we have investigated their involvement in metal and DNA binding. Results: Re...

  8. Sigma factor genes sigC, sigE, and sigG are upregulated in heterocysts of the cyanobacterium Anabaena sp. strain PCC 7120.

    Science.gov (United States)

    Aldea, M Ramona; Mella-Herrera, Rodrigo A; Golden, James W

    2007-11-01

    We used gfp transcriptional fusions to investigate the regulation of eight sigma factor genes during heterocyst development in the cyanobacterium Anabaena sp. strain PCC 7120. Reporter strains containing gfp fusions with the upstream regions of sigB2, sigD, sigI, and sigJ did not show developmental regulation. Time-lapse microscopy of sigC, sigE, and sigG reporter strains showed increased green fluorescent protein fluorescence in differentiating cells at 4 h, 16 h, and 9 h, respectively, after nitrogen step down.

  9. Involvement of thioredoxin on the scaffold activity of NifU in heterocyst cells of the diazotrophic cyanobacterium Anabaena sp. strain PCC 7120.

    Science.gov (United States)

    Nomata, Jiro; Maeda, Maki; Isu, Atsuko; Inoue, Kazuhito; Hisabori, Toru

    2015-09-01

    The diazotrophic cyanobacterium Anabaena sp. strain PCC 7120 (A.7120) differentiates into specialized heterocyst cells that fix nitrogen under nitrogen starvation conditions. Although reducing equivalents are essential for nitrogen fixation, little is known about redox systems in heterocyst cells. In this study, we investigated thioredoxin (Trx) networks in Anabaena using TrxM, and identified 16 and 38 candidate target proteins in heterocysts and vegetative cells, respectively, by Trx affinity chromatography (Motohashi et al. (Comprehensive survey of proteins targeted by chloroplast thioredoxin. Proc Natl Acad Sci USA, 2001; 98: , 11224-11229)). Among these, the Fe-S cluster scaffold protein NifU that facilitates functional expression of nitrogenase in heterocysts was found to be a potential TrxM target. Subsequently, we observed that the scaffold activity of N-terminal catalytic domain of NifU is enhanced in the presence of Trx-system, suggesting that TrxM is involved in the Fe-S cluster biogenesis.

  10. LexA protein of cyanobacterium Anabaena sp. strain PCC7120 exhibits in vitro pH-dependent and RecA-independent autoproteolytic activity.

    Science.gov (United States)

    Kumar, Arvind; Kirti, Anurag; Rajaram, Hema

    2015-02-01

    The LexA protein of the nitrogen-fixing cyanobacterium, Anabaena sp. strain PCC7120 exhibits a RecA-independent and alkaline pH-dependent autoproteolytic cleavage. The autoproteolytic cleavage of Anabaena LexA occurs at pH 8.5 and above, stimulated by the addition of Ca(2+) and in the temperature range of 30-57°C. Mutational analysis of Anabaena LexA protein indicated that the cleavage occurred at the peptide bond between Ala-84 and Gly-85, and optimal cleavage required the presence of Ser-118 and Lys-159, as also observed for LexA protein of Escherichia coli. Cleavage of Anabaena LexA was affected upon deletion of three amino acids, (86)GLI. These three amino acids are unique to all cyanobacterial LexA proteins predicted to be cleavable. The absence of RecA-dependent cleavage at physiological pH, which has not been reported for other bacterial LexA proteins, is possibly due to the absence of RecA interacting sites on Anabaena LexA protein, corresponding to the residues identified in E. coli LexA, and low cellular levels of RecA in Anabaena. Exposure to SOS-response inducing stresses, such as UV-B and mitomycin C neither affected the expression of LexA in Anabaena nor induced cleavage of LexA in either Anabaena 7120 or E. coli overexpressing Anabaena LexA protein. Though the LexA may be acting as a repressor by binding to the LexA box in the vicinity of the promoter region of specific gene, their derepression may not be via proteolytic cleavage during SOS-inducing stresses, unless the stress induces increase in cytoplasmic pH. This could account for the regulation of several carbon metabolism genes rather than DNA-repair genes under the regulation of LexA in cyanobacteria especially during high light induced oxidative stress.

  11. Regulation of pepc gene expression in Anabaena sp. PCC 7120 and its effects on cyclic electron flow around photosystem I and tolerances to environmental stresses

    Institute of Scientific and Technical Information of China (English)

    Xiao-Hui Jia; Peng-Peng Zhang; Ding-Ji Shi; Hua-Ling Mi; Jia-Cheng Zhu; Xi-Wen Huang; Pei-Min He

    2015-01-01

    Since pepc gene encoding phosphoenolpyruvate carboxylase (PEPCase) has been cloned from Anabaena sp. PCC 7120 and other cyanobacteria, the effects of pepc gene expression on photosynthesis have not been reported yet. In this study, we constructed mutants containing either upregu-lated (forward) or downregulated (reverse) pepc gene in Anabaena sp. PCC 7120. Results from real‐time quantitative polymerase chain reaction (RT‐qPCR), Western blot and enzymatic analysis showed that PEPCase activity was signifi-cantly reduced in the reverse mutant compared with the wild type, and that of the forward mutant was obviously increased. Interestingly, the net photosynthesis in both the reverse mutant and the forward mutant were higher than that of the wild type, but dark respiration was decreased only in the reverse mutant. The absorbance changes of P700 upon saturation pulse showed the photosystem I (PSI) activity was inhibited, as reflected by Y(I), and Y(NA) was elevated, and dark reduction of P700þ was stimulated, indicating enhanced cyclic electron flow (CEF) around PSI in the reverse mutant. Additional y, the reverse mutant photosynthesis was higher than that of the wild type in low temperature, low and high pH, and high salinity, and this implies increased tolerance in the reverse mutant through downregulated pepc gene.

  12. Construction of shuttle, expression vector of human tumor necrosis factor alpha (hTNF-α) gene and its expression in a cyanobacterium, Anabaena sp. PCC 7120

    Institute of Scientific and Technical Information of China (English)

    刘凤龙; 施定基; 商之狄; 邵宁; 徐旭东; 钟泽璞; 张宏斌; 吴锦银; 王捷; 江悦华; 赵树进; 林晨; 张雪艳; 吴旻; 彭国宏; 张海霞; 曾呈奎

    1999-01-01

    The construction of the shuttle, expression vector of human tumor necrosis factor alpha (hTNF-a) gene and its expression in a cyanobacterium Anabaena sp. PCC 7120 was reported. The 700-bp hTNF cDNA fragments have been recovered from plasmid pRL-rhTNF, then inserted downstream of the promoter PpsbA in the plasmid pRL439. The resultant intermediary plasmid pRL-TC has further been combined with the shuttle vector pDC-8 to get the shuttle, expression vector pDC-TNF. The expression of the rhTNF gene in Escherichia coli has been analyzed by SDS-PAGE and thin-layer scanning, and the results show that the expressed TNF protein with these two vectors is 16.9 percent (pRL-TC) and 15.0 percent (pDC-TNF) of the total proteins in the cells, respectively, while the expression level of TNF gene in plasmid pRL-rhTNF is only 11.8 percent. Combined with the participation of the conjugal and helper plasmids, pDC-TNF has been introduced into Anabaena sp PCC 7120 by triparental conjugative transfer, and the stable transgenic

  13. Regulation of pepc gene expression in Anabaena sp. PCC 7120 and its effects on cyclic electron flow around photosystem I and tolerances to environmental stresses.

    Science.gov (United States)

    Jia, Xiao-Hui; Zhang, Peng-Peng; Shi, Ding-Ji; Mi, Hua-Ling; Zhu, Jia-Cheng; Huang, Xi-Wen; He, Pei-Min

    2015-05-01

    Since pepc gene encoding phosphoenolpyruvate carboxylase (PEPCase) has been cloned from Anabaena sp. PCC 7120 and other cyanobacteria, the effects of pepc gene expression on photosynthesis have not been reported yet. In this study, we constructed mutants containing either upregulated (forward) or downregulated (reverse) pepc gene in Anabaena sp. PCC 7120. Results from real-time quantitative polymerase chain reaction (RT-qPCR), Western blot and enzymatic analysis showed that PEPCase activity was significantly reduced in the reverse mutant compared with the wild type, and that of the forward mutant was obviously increased. Interestingly, the net photosynthesis in both the reverse mutant and the forward mutant were higher than that of the wild type, but dark respiration was decreased only in the reverse mutant. The absorbance changes of P700 upon saturation pulse showed the photosystem I (PSI) activity was inhibited, as reflected by Y(I), and Y(NA) was elevated, and dark reduction of P700(+) was stimulated, indicating enhanced cyclic electron flow (CEF) around PSI in the reverse mutant. Additionally, the reverse mutant photosynthesis was higher than that of the wild type in low temperature, low and high pH, and high salinity, and this implies increased tolerance in the reverse mutant through downregulated pepc gene.

  14. Secretome analysis of Anabaena sp. PCC 7120 and the involvement of the TolC-homologue HgdD in protein secretion.

    Science.gov (United States)

    Hahn, Alexander; Stevanovic, Mara; Brouwer, Eva; Bublak, Daniela; Tripp, Joanna; Schorge, Tobias; Karas, Michael; Schleiff, Enrico

    2015-03-01

    Secretion of proteins is a central strategy of bacteria to influence and respond to their environment. Until now, there has been very few discoveries regarding the cyanobacterial secrotome or the secretion machineries involved. For a mutant of the outer membrane channel TolC-homologue HgdD of Anabaena sp. PCC 7120, a filamentous and heterocyst-forming cyanobacterium, an altered secretome profile was reported. To define the role of HgdD in protein secretion, we have developed a method to isolate extracellular proteins of Anabaena sp. PCC 7120 wild type and an hgdD loss-of-function mutant. We identified 51 proteins of which the majority is predicted to have an extracellular secretion signal, while few seem to be localized in the periplasmic space. Eight proteins were exclusively identified in the secretome of wild-type cells, which coincides with the distribution of type I secretion signal. We selected three candidates and generated hemagglutinin-tagged fusion proteins which could be exclusively detected in the extracellular protein fraction. However, these proteins are not secreted in the hgdD-mutant background, where they are rapidly degraded. This confirms a direct function of HgdD in protein secretion and points to the existence of a quality control mechanism at least for proteins secreted in an HgdD-dependent pathway.

  15. Zur (FurB) is a key factor in the control of the oxidative stress response in Anabaena sp. PCC 7120.

    Science.gov (United States)

    Sein-Echaluce, Violeta C; González, Andrés; Napolitano, Mauro; Luque, Ignacio; Barja, Francisco; Peleato, M Luisa; Fillat, María F

    2015-06-01

    Iron and zinc are necessary nutrients whose homeostasis is tightly controlled by members of the ferric uptake regulator (FUR) superfamily in the cyanobacterium Anabaena sp. PCC7120. Although the link between iron metabolism and oxidative stress management is well documented, little is known about the connection between zinc homeostasis and the oxidative stress response in cyanobacteria. Zinc homeostasis in Anabaena is controlled by Zur, also named FurB. When overexpressed in Escherichia coli, Zur (FurB) improved cell survival during oxidative stress. In order to investigate the possible correlation between Zur and the oxidative stress response in Anabaena, zur deletion and zur-overexpressing strains have been constructed, and the consequences of Zur imbalance evaluated. The lack of Zur increased sensitivity to hydrogen peroxide (H2 O2 ), whereas an excess of Zur enhanced oxidative stress resistance. Both mutants displayed pleiotropic phenotypes, including alterations on the filament surfaces observable by scanning electron microscopy, reduced content of endogenous H2 O2 and altered expression of sodA, catalases and several peroxiredoxins. Transcriptional and biochemical analyses unveiled that the appropriate level of Zur is required for proper control of the oxidative stress response and allowed us to identify major antioxidant enzymes as novel members of the Zur regulon.

  16. Directional RNA deep sequencing sheds new light on the transcriptional response of Anabaena sp. strain PCC 7120 to combined-nitrogen deprivation

    Directory of Open Access Journals (Sweden)

    Head Steven R

    2011-06-01

    Full Text Available Abstract Background Cyanobacteria are potential sources of renewable chemicals and biofuels and serve as model organisms for bacterial photosynthesis, nitrogen fixation, and responses to environmental changes. Anabaena (Nostoc sp. strain PCC 7120 (hereafter Anabaena is a multicellular filamentous cyanobacterium that can "fix" atmospheric nitrogen into ammonia when grown in the absence of a source of combined nitrogen. Because the nitrogenase enzyme is oxygen sensitive, Anabaena forms specialized cells called heterocysts that create a microoxic environment for nitrogen fixation. We have employed directional RNA-seq to map the Anabaena transcriptome during vegetative cell growth and in response to combined-nitrogen deprivation, which induces filaments to undergo heterocyst development. Our data provide an unprecedented view of transcriptional changes in Anabaena filaments during the induction of heterocyst development and transition to diazotrophic growth. Results Using the Illumina short read platform and a directional RNA-seq protocol, we obtained deep sequencing data for RNA extracted from filaments at 0, 6, 12, and 21 hours after the removal of combined nitrogen. The RNA-seq data provided information on transcript abundance and boundaries for the entire transcriptome. From these data, we detected novel antisense transcripts within the UTRs (untranslated regions and coding regions of key genes involved in heterocyst development, suggesting that antisense RNAs may be important regulators of the nitrogen response. In addition, many 5' UTRs were longer than anticipated, sometimes extending into upstream open reading frames (ORFs, and operons often showed complex structure and regulation. Finally, many genes that had not been previously identified as being involved in heterocyst development showed regulation, providing new candidates for future studies in this model organism. Conclusions Directional RNA-seq data were obtained that provide

  17. in-silico analysis suggests alterations in the function of XisA protein as a possible mechanism of butachlor toxicity in the nitrogen fixing cyanobacterium Anabaena sp. PCC 7120.

    Science.gov (United States)

    Singh, Shilpi; Singh, Prem Pal

    2013-01-01

    Butachlor, a commonly used herbicide adversely affects the nitrogen fixing capability of Anabaena, an acclaimed nitrogen fixer in the Indian paddy fields. The nitrogen fixation in Anabaena is triggered by the excision of nifD element by xisA gene leading to rearrangement of nifD forming nifHDK operon in the heterocyst of Anabaena sp. PCC7120. Functional elucidation adjudged through in-silico analysis revealed that xisA belongs to integrase family of tyrosine recombinase. The predicted functional partners with XisA protein that have shown cooccurence with this protein in a network are mainly hypothetical proteins with unknown functions except psaK1 whose exact function in photosystem I is not yet known. The focus of this study was to find out the relation between XisA and butachlor using in-silico approaches. The XisA protein was modeled and its active sites were identified. Docking studies revealed that butachlor binds at the active site of XisA protein hampering its excision ability vis-à-vis nif genes in Anabaena sp. PCC7120. This study reveals that butachlor is not directly involved in hampering the nitrogen fixing ability of Anabaena sp. PCC7120 but by arresting the excision ability of XisA protein necessary for the functioning of nif gene and nitrogen fixation.

  18. 蓝藻Anabaena sp.strain PCC7120中一种可诱导的CO2浓缩机制(CCM)

    Institute of Scientific and Technical Information of China (English)

    吴天福; 宋立荣; 刘永定

    1999-01-01

    为了探讨蓝藻Anabaena sp.strain PCC7120在外源无机碳浓度变化时,其光合作用对CO2和HCO-3的利用特性,制备了高CO2适应细胞(High-CO2-growing cells,HCG细胞).Anabaena sp.strain PCC7120 HCG细胞的生长速率高于LCG细胞(Low-CO2-Growing Cells),即在空气中生长的细胞.当HCG细胞从5% CO2转移到空气中时,其碳酸酐酶活性升高;它对外源无机碳的表观光合作用亲合力明显提高,说明它的CCM活性被诱导.HCG细胞与LCG细胞一样,当环境中pH值从6升高到9时,对外源无机碳的表观光合作用亲合力都降低,而对外源CO2的表观光合作用亲合力则升高.当HCG细胞从5% CO2转移到空气中时,作为CCM重要元件的羧体数目明显增加.以上结果表明:这种可诱导的CCM,为水体环境中光合自养生物无机碳利用特性的研究提供了一个很好的模型.

  19. Mutagenesis of hetR reveals amino acids necessary for HetR function in the heterocystous cyanobacterium Anabaena sp. strain PCC 7120.

    Science.gov (United States)

    Risser, Douglas D; Callahan, Sean M

    2007-03-01

    HetR is the master regulator of heterocyst differentiation in the filamentous cyanobacterium Anabaena sp. strain PCC 7120. Genetic selection was used to identify 33 amino acid substitutions in HetR that reduced the proportion of cells undergoing heterocyst differentiation to less than 2%. Conservative substitutions in the wild-type HetR protein revealed three mutations that dramatically reduced the amount of heterocyst differentiation when the mutant allele was present in place of the wild-type allele on a replicating plasmid in a mutant lacking hetR on the chromosome. An H69Y substitution resulted in heterocyst formation among less than 0.1% of cells, and D17E and G36A substitutions resulted in a Het- phenotype, compared to heterocyst formation among approximately 25% of cells with the wild-type hetR under the same conditions. The D17E substitution prevented DNA binding activity exhibited by wild-type HetR in mobility shift assays, whereas G36A and H69Y substitutions had no affect on DNA binding. D17E, G36A, and H69Y substitutions also resulted in higher levels of the corresponding HetR protein than of the wild-type protein when each was expressed from an inducible promoter in a hetR deletion strain, suggesting an effect on HetR protein turnover. Surprisingly, C48A and S152A substitutions, which were previously reported to result in a Het- phenotype, were found to have no effect on heterocyst differentiation or patterning when the corresponding mutations were introduced into an otherwise wild-type genetic background in Anabaena sp. strain PCC 7120. The clustering of mutations that satisfied the positive selection near the amino terminus suggests an important role for this part of the protein in HetR function.

  20. EXPRESSION OF HUMAN TUMOR NECROSIS FACTORαIN ANABAENA SP. PCC7120%人肿瘤坏死因子α在鱼腥藻7120中的表达

    Institute of Scientific and Technical Information of China (English)

    王捷; 郭勇

    1999-01-01

    Anabaena-E.coli shuttle plasmid PDC-TNF containing the coding region of the human TNF-α and psbA promoter was transformed to unicellular filamentous cyanobacterium Anabaena sp. PCC7120 by triparent conjugation. Southern hybridization results show that human TNF-α cDNA is capable of autonomous replication as PDC-TNF plasmid in Anabaena sp. PCC7120 cells. It is shown that Anabaena sp. PCC7120 harboring PDC-TNF plasmid expresses human TNF-α at a high level (about 16% of total cyanobacterial proteins) with apparent molecular mass of 17ku by SDS-PAGE and Western blotting analysis. The specific activity of TNF is about 2.5×104u/mg in the crude extract of Anabaena sp. PCC7120 harboring PDC-TNF plasmid.%通过三亲结合转移方式,将含人肿瘤坏死因子α(TNF-α) cDNA和psbA启动子的鱼腥藻-大肠杆菌穿梭质粒PDC-TNF导入单细胞丝状鱼腥藻7120中.Southern杂交结果表明,人肿瘤坏死因子α cDNA在鱼腥藻7120细胞中能以自主复制形式存在于PDC-TNF质粒上.SDS-PAGE和免疫印迹分析结果显示,转PDC-TNF的鱼腥藻7120可表达分子量约为17ku的人TNF-α,其表达量约占藻体蛋白的16%左右.转PDC-TNF的鱼腥藻7120粗提液的TNF生物学比活性约为2.5×104 u/mg.

  1. Site-directed mutagenesis of the Anabaena sp. strain PCC 7120 nitrogenase active site to increase photobiological hydrogen production.

    Science.gov (United States)

    Masukawa, Hajime; Inoue, Kazuhito; Sakurai, Hidehiro; Wolk, C Peter; Hausinger, Robert P

    2010-10-01

    Cyanobacteria use sunlight and water to produce hydrogen gas (H₂), which is potentially useful as a clean and renewable biofuel. Photobiological H₂ arises primarily as an inevitable by-product of N₂ fixation by nitrogenase, an oxygen-labile enzyme typically containing an iron-molybdenum cofactor (FeMo-co) active site. In Anabaena sp. strain 7120, the enzyme is localized to the microaerobic environment of heterocysts, a highly differentiated subset of the filamentous cells. In an effort to increase H₂ production by this strain, six nitrogenase amino acid residues predicted to reside within 5 Å of the FeMo-co were mutated in an attempt to direct electron flow selectively toward proton reduction in the presence of N₂. Most of the 49 variants examined were deficient in N₂-fixing growth and exhibited decreases in their in vivo rates of acetylene reduction. Of greater interest, several variants examined under an N₂ atmosphere significantly increased their in vivo rates of H₂ production, approximating rates equivalent to those under an Ar atmosphere, and accumulated high levels of H₂ compared to the reference strains. These results demonstrate the feasibility of engineering cyanobacterial strains for enhanced photobiological production of H₂ in an aerobic, nitrogen-containing environment.

  2. The hypothetical protein 'All4779', and not the annotated 'Alr0088' and 'Alr7579' proteins, is the major typical single-stranded DNA binding protein of the cyanobacterium, Anabaena sp. PCC7120.

    Science.gov (United States)

    Kirti, Anurag; Rajaram, Hema; Apte, Shree Kumar

    2014-01-01

    Single-stranded DNA binding (SSB) proteins are essential for all DNA-dependent cellular processes. Typical SSB proteins have an N-terminal Oligonucleotide-Binding (OB) fold, a Proline/Glycine rich region, followed by a C-terminal acidic tail. In the genome of the heterocystous nitrogen-fixing cyanobacterium, Anabaena sp. strain PCC7120, alr0088 and alr7579 are annotated as coding for SSB, but are truncated and have only the OB-fold. In silico analysis of whole genome of Anabaena sp. strain PCC7120 revealed the presence of another ORF 'all4779', annotated as a hypothetical protein, but having an N-terminal OB-fold, a P/G-rich region and a C-terminal acidic tail. Biochemical characterisation of all three purified recombinant proteins revealed that they exist either as monomer or dimer and bind ssDNA, but differently. The All4779 bound ssDNA in two binding modes i.e. (All4779)35 and (All4779)66 depending on salt concentration and with a binding affinity similar to that of Escherichia coli SSB. On the other hand, Alr0088 bound in a single binding mode of 50-mer and Alr7579 only to large stretches of ssDNA, suggesting that All4779, in all likelihood, is the major typical bacterial SSB in Anabaena. Overexpression of All4779 in Anabaena sp. strain PCC7120 led to enhancement of tolerance to DNA-damaging stresses, such as γ-rays, UV-irradiation, desiccation and mitomycinC exposure. The tolerance appears to be a consequence of reduced DNA damage or efficient DNA repair due to increased availability of All4779. The ORF all4779 is proposed to be re-annotated as Anabaena ssb gene.

  3. Molecular characterization of Alr1105 a novel arsenate reductase of the diazotrophic cyanobacterium Anabaena sp. PCC7120 and decoding its role in abiotic stress management in Escherichia coli.

    Science.gov (United States)

    Pandey, Sarita; Shrivastava, Alok K; Rai, Rashmi; Rai, Lal Chand

    2013-11-01

    This paper constitutes the first report on the Alr1105 of Anabaena sp. PCC7120 which functions as arsenate reductase and phosphatase and offers tolerance against oxidative and other abiotic stresses in the alr1105 transformed Escherichia coli. The bonafide of 40.8 kDa recombinant GST+Alr1105 fusion protein was confirmed by immunoblotting. The purified Alr1105 protein (mw 14.8 kDa) possessed strong arsenate reductase (Km 16.0 ± 1.2 mM and Vmax 5.6 ± 0.31 μmol min⁻¹ mg protein⁻¹) and phosphatase activity (Km 27.38 ± 3.1 mM and Vmax 0.077 ± 0.005 μmol min⁻¹ mg protein⁻¹) at an optimum temperature 37 °C and 6.5 pH. Native Alr1105 was found as a monomeric protein in contrast to its homologous Synechocystis ArsC protein. Expression of Alr1105 enhanced the arsenic tolerance in the arsenate reductase mutant E. coli WC3110 (∆arsC) and rendered better growth than the wild type W3110 up to 40 mM As (V). Notwithstanding above, the recombinant E. coli strain when exposed to CdCl₂, ZnSO₄, NiCl₂, CoCl₂, CuCl₂, heat, UV-B and carbofuron showed increase in growth over the wild type and mutant E. coli transformed with the empty vector. Furthermore, an enhanced growth of the recombinant E. coli in the presence of oxidative stress producing chemicals (MV, PMS and H₂O₂), suggested its protective role against these stresses. Appreciable expression of alr1105 gene as measured by qRT-PCR at different time points under selected stresses reconfirmed its role in stress tolerance. Thus the Alr1105 of Anabaena sp. PCC7120 functions as an arsenate reductase and possess novel properties different from the arsenate reductases known so far.

  4. Subcellular localization and clues for the function of the HetN factor influencing heterocyst distribution in Anabaena sp. strain PCC 7120.

    Science.gov (United States)

    Corrales-Guerrero, Laura; Mariscal, Vicente; Nürnberg, Dennis J; Elhai, Jeff; Mullineaux, Conrad W; Flores, Enrique; Herrero, Antonia

    2014-10-01

    In the filamentous cyanobacterium Anabaena sp. strain PCC 7120, heterocysts are formed in the absence of combined nitrogen, following a specific distribution pattern along the filament. The PatS and HetN factors contribute to the heterocyst pattern by inhibiting the formation of consecutive heterocysts. Thus, inactivation of any of these factors produces the multiple contiguous heterocyst (Mch) phenotype. Upon N stepdown, a HetN protein with its C terminus fused to a superfolder version of green fluorescent protein (sf-GFP) or to GFP-mut2 was observed, localized first throughout the whole area of differentiating cells and later specifically on the peripheries and in the polar regions of mature heterocysts, coinciding with the location of the thylakoids. Polar localization required an N-terminal stretch comprising residues 2 to 27 that may represent an unconventional signal peptide. Anabaena strains expressing a version of HetN lacking this fragment from a mutant gene placed at the native hetN locus exhibited a mild Mch phenotype. In agreement with previous results, deletion of an internal ERGSGR sequence, which is identical to the C-terminal sequence of PatS, also led to the Mch phenotype. The subcellular localization in heterocysts of fluorescence resulting from the fusion of GFP to the C terminus of HetN suggests that a full HetN protein is present in these cells. Furthermore, the full HetN protein is more conserved among cyanobacteria than the internal ERGSGR sequence. These observations suggest that HetN anchored to thylakoid membranes in heterocysts may serve a function besides that of generating a regulatory (ERGSGR) peptide.

  5. 温度对普通小球藻和鱼腥藻生长竞争的影响%EFFECT OF TEMPERATURE ON GROWTH AND COMPETITION OF CHLORELLA VULGARISRIS AND ANABAENA SP. STRAIN PCC

    Institute of Scientific and Technical Information of China (English)

    王菁; 裘丽萍; 孟顺龙; 范立民; 宋超; 陈家长

    2014-01-01

    Chlorella vulgaris is a common freshwater alga. Anabaena sp. strain PCC is one of the most common blue-green alga in eutrophic lakes. To better understand the growth of water bloom blue-green alga in eutrophic lakes and the relationship between alga growth and temperature, we investigate the interspecies competition between C. vul-garis and Anabaena sp. strain PCC at different temperatures. The results showed that in both uni-culture and co-culture systems, C. vulgaris and Anabaena sp. strain PCC reached the maximum growth rates at 35℃ and 30-35℃ respec-tively. We also found that the inhibition parameters of interspecies competition could be significantly influenced by the temperature. The maximum inhibition parameter of Anabaena sp. strain PCC against C. vulgaris, 0.9111, was observed at 15℃. This value was 1.24, 1.14, and 1.12 times higher than the parameters at 25, 30℃, and 35℃ respectively. The maximum inhibition parameter of C. vulgaris against Anabaena sp. strain PCC, 18.38, was observed at 30℃, which was 4.25, 2.03, and 1.20 times higher than those at 15℃, 25℃, and 35℃ respectively. According to the Lotka-Volterra model, we deducted that the coexistence of Anabaena sp. strain PCC and C. vulgaris was unstable in the co-culture system at these four temperatures.%通过室内实验研究了不同温度条件下主要水华藻类--鱼腥藻(Anabaena sp. strain PCC)和常见淡水藻类--普通小球藻(Chlorella vulgaris)的生长和种间竞争,结果表明在单种培养和共同培养体系中,普通小球藻的最大藻细胞浓度随着温度的升高而增加;鱼腥藻生长最适温度为30-35℃。温度对藻类种间竞争抑制参数能够产生明显影响,鱼腥藻在温度为15℃时对普通小球藻的竞争抑制参数最大,分别是25℃、30℃、35℃时的1.24倍、1.14倍和1.12倍;而普通小球藻在30℃时对鱼腥藻的竞争抑制参数最大,分别是15℃、25℃、35℃条件下的4.25倍、2.03

  6. Enhanced Thermostability of Lipoxygenase from Anabaena sp. PCC 7120 by Site-Directed Mutagenesis Based on Computer-Aided Rational Design.

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    Diao, Hanwen; Zhang, Chong; Wang, Shuicheng; Lu, Fengxia; Lu, Zhaoxin

    2016-04-01

    Lipoxygenase from Anabaena sp. PCC 7120 (Ana-LOX) was thermally unstable. So, improving the thermostability of the enzyme was quite essential. The target site of Ana-LOX selected for site-directed mutagenesis was based on computer-aided rational design. The thermostability and specific activity of Ana-LOX were improved with replacing valine with alanine at the target site 421 and the site 40. Compared to the wild-type enzyme which has a half-life (T 1/2) of inactivation of 3.8 min at 50 °C, the T 1/2 of mutant enzymes with V421A and V40A substitution increased to 4.4 and 7.0 min, respectively. The double mutant V421A/V40A showed a synergistic effect with a T 1/2 value of 8.3 min, resulting in a 1.18-fold improvement compared to the original Ana-LOX. V421A, V40A, and V421A/V40A also obtained 4.83, 41.58, and 80.07 % increase in specific activity, respectively. This study provides useful theoretical reference for enzyme molecular modification and computer-aided rational design.

  7. Cysteine Mutational Studies Provide Insight into a Thiol-Based Redox Switch Mechanism of Metal and DNA Binding in FurA from Anabaena sp. PCC 7120

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    Botello-Morte, Laura; Pellicer, Silvia; Sein-Echaluce, Violeta C.; Contreras, Lellys M.; Neira, José Luis; Abián, Olga; Velázquez-Campoy, Adrián; Peleato, María Luisa; Fillat, María F.

    2016-01-01

    Abstract Aims: The ferric uptake regulator (Fur) is the main transcriptional regulator of genes involved in iron homeostasis in most prokaryotes. FurA from Anabaena sp. PCC 7120 contains five cysteine residues, four of them arranged in two redox-active CXXC motifs. The protein needs not only metal but also reducing conditions to remain fully active in vitro. Through a mutational study of the cysteine residues present in FurA, we have investigated their involvement in metal and DNA binding. Results: Residue C101 that belongs to a conserved CXXC motif plays an essential role in both metal and DNA binding activities in vitro. Substitution of C101 by serine impairs DNA and metal binding abilities of FurA. Isothermal titration calorimetry measurements show that the redox state of C101 is responsible for the protein ability to coordinate the metal corepressor. Moreover, the redox state of C101 varies with the presence or absence of C104 or C133, suggesting that the environments of these cysteines are mutually interdependent. Innovation: We propose that C101 is part of a thiol/disulfide redox switch that determines FurA ability to bind the metal corepressor. Conclusion: This mechanism supports a novel feature of a Fur protein that emerges as a regulator, which connects the response to changes in the intracellular redox state and iron management in cyanobacteria. Antioxid. Redox Signal. 24, 173–185. PMID:26414804

  8. Crystal structure of NblA from Anabaena sp. PCC 7120, a small protein playing a key role in phycobilisome degradation.

    Science.gov (United States)

    Bienert, Ralf; Baier, Kerstin; Volkmer, Rudolf; Lockau, Wolfgang; Heinemann, Udo

    2006-02-24

    Cyanobacterial light-harvesting complexes, the phycobilisomes, are proteolytically degraded when the organisms are starved for combined nitrogen, a process referred to as chlorosis or bleaching. Gene nblA, present in all phycobilisome-containing organisms, encodes a protein of about 7 kDa that plays a key role in phycobilisome degradation. The mode of action of NblA in this degradation process is poorly understood. Here we presented the 1.8-A crystal structure of NblA from Anabaena sp. PCC 7120. In the crystal, NblA is present as a four-helix bundle formed by dimers, the basic structural units. By using pull-down assays with immobilized NblA and peptide scanning, we showed that NblA specifically binds to the alpha-subunits of phycocyanin and phycoerythrocyanin, the main building blocks of the phycobilisome rod structure. By site-directed mutagenesis, we identified amino acid residues in NblA that are involved in phycobilisome binding. The results provided evidence that NblA is directly involved in phycobilisome degradation, and the results allowed us to present a model that gives insight into the interaction of this small protein with the phycobilisomes.

  9. Treatment with moderate concentrations of NaHSO{sub 3} enhances photobiological H{sub 2} production in the cyanobacterium Anabaena sp. strain PCC 7120

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    Wang, Lianjun; Chen, Ming; Wei, Lanzhen; Gao, Fudan; Lv, Zhongxian; Wang, Quanxi; Ma, Weimin [College of Life and Environment Sciences, Shanghai Normal University, Guilin Road 100, Shanghai 200234 (China)

    2010-12-15

    In cyanobacteria, treatment with low concentrations of NaHSO{sub 3} can enhance photosynthetic efficiency, whereas NaHSO{sub 3} in high amounts often inhibits cell growth and photosynthesis may even cause death. In the present study, our results showed that treatment with moderate concentrations of NaHSO{sub 3} considerably improved the yield of photobiological H{sub 2} production in the filamentous N{sub 2}-fixing cyanobacterium Anabaena sp. strain PCC 7120. Under steady state conditions, the accumulated H{sub 2} levels in cells treated with 1 mM NaHSO{sub 3} were approximately 10 times higher than that in untreated cells. Such improvement occurred in heterocysts and was most likely caused by increases in the expression and activity of nitrogenase. The effects of treatment with low, moderate, and high concentrations of NaHSO{sub 3} in cyanobacteria were proposed on the basis of the results obtained in the present study and from previous knowledge. (author)

  10. The trpE gene negatively regulates differentiation of heterocysts at the level of induction in Anabaena sp. strain PCC 7120.

    Science.gov (United States)

    Videau, Patrick; Cozy, Loralyn M; Young, Jasmine E; Ushijima, Blake; Oshiro, Reid T; Rivers, Orion S; Burger, Andrew H; Callahan, Sean M

    2015-01-01

    Levels of 2-oxoglutarate (2-OG) reflect nitrogen status in many bacteria. In heterocystous cyanobacteria, a spike in the 2-OG level occurs shortly after the removal of combined nitrogen from cultures and is an integral part of the induction of heterocyst differentiation. In this work, deletion of one of the two annotated trpE genes in Anabaena sp. strain PCC 7120 resulted in a spike in the 2-OG level and subsequent differentiation of a wild-type pattern of heterocysts when filaments of the mutant were transferred from growth on ammonia to growth on nitrate. In contrast, 2-OG levels were unaffected in the wild type, which did not differentiate under the same conditions. An inverted-repeat sequence located upstream of trpE bound a central regulator of differentiation, HetR, in vitro and was necessary for HetR-dependent transcription of a reporter fusion and complementation of the mutant phenotype in vivo. Functional complementation of the mutant phenotype with the addition of tryptophan suggested that levels of tryptophan, rather than the demonstrated anthranilate synthase activity of TrpE, mediated the developmental response of the wild type to nitrate. A model is presented for the observed increase in 2-OG in the trpE mutant.

  11. Characterization and responses to environmental cues of a photosynthetic antenna-deficient mutant of the filamentous cyanobacterium Anabaena sp. PCC 7120.

    Science.gov (United States)

    Leganés, Francisco; Martínez-Granero, Francisco; Muñoz-Martín, M Ángeles; Marco, Eduardo; Jorge, Alberto; Carvajal, Laura; Vida, Teresa; González-Pleiter, Miguel; Fernández-Piñas, Francisca

    2014-07-01

    The cyanobacterial phycobilisome (PBS) is a giant pigment-protein complex which harvests light energy for photosynthesis and comprises two structures: a core and peripheral rods. Most studies on PBS structure and function are based on mutants of unicellular strains. In this report, we describe the phenotypic and genetic characterization of a transposon mutant of the filamentous Anabaena sp. strain PCC 7120, denoted LC1, which cannot synthesize the phycobiliprotein phycocyanin (PC), the main component of the rods; in this mutant, the transposon had inserted into the cpcB gene (orf alr0528) which putatively encodes PC-β chain. Mutant LC1 was able to synthesize phycoerythrocyanin (PEC), a phycobiliprotein (PBP) located at the terminal region of the rods; but in the absence of PC, PEC did not attach to the PBSs that only retained the allophycocyanin (APC) core; ferredoxin: NADP+-oxidoreductase (FNR) that is associated with the PBS in the wild type, was not found in isolated PBSs from LC1. The performance of the mutant exposed to different environmental conditions was evaluated. The mutant phenotype was successfully complemented by cloning and transfer of the wild type complete cpc operon to mutant LC1. Interestingly, LC1 compensated its mutation by significantly increasing the number of its core-PBS and the effective quantum yield of photosystem II (PSII) photochemistry; this feature suggests a more efficient energy conversion in the mutant which may be useful for biotechnological applications.

  12. Sucrose synthesis in the nitrogen-fixing Cyanobacterium Anabaena sp. strain PCC 7120 is controlled by the two-component response regulator OrrA.

    Science.gov (United States)

    Ehira, Shigeki; Kimura, Satoshi; Miyazaki, Shogo; Ohmori, Masayuki

    2014-09-01

    The filamentous, nitrogen-fixing cyanobacterium Anabaena sp. strain PCC 7120 accumulates sucrose as a compatible solute against salt stress. Sucrose-phosphate synthase activity, which is responsible for the sucrose synthesis, is increased by salt stress, but the mechanism underlying the regulation of sucrose synthesis remains unknown. In the present study, a response regulator, OrrA, was shown to control sucrose synthesis. Expression of spsA, which encodes a sucrose-phosphate synthase, and susA and susB, which encode sucrose synthases, was induced by salt stress. In the orrA disruptant, salt induction of these genes was completely abolished. The cellular sucrose level of the orrA disruptant was reduced to 40% of that in the wild type under salt stress conditions. Moreover, overexpression of orrA resulted in enhanced expression of spsA, susA, and susB, followed by accumulation of sucrose, without the addition of NaCl. We also found that SigB2, a group 2 sigma factor of RNA polymerase, regulated the early response to salt stress under the control of OrrA. It is concluded that OrrA controls sucrose synthesis in collaboration with SigB2.

  13. Dynamics and Cell-Type Specificity of the DNA Double-Strand Break Repair Protein RecN in the Developmental Cyanobacterium Anabaena sp. Strain PCC 7120.

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    Sheng Hu

    Full Text Available DNA replication and repair are two fundamental processes required in life proliferation and cellular defense and some common proteins are involved in both processes. The filamentous cyanobacterium Anabaena sp. strain PCC 7120 is capable of forming heterocysts for N2 fixation in the absence of a combined-nitrogen source. This developmental process is intimately linked to cell cycle control. In this study, we investigated the localization of the DNA double-strand break repair protein RecN during key cellular events, such as chromosome damaging, cell division, and heterocyst differentiation. Treatment by a drug causing DNA double-strand breaks (DSBs induced reorganization of the RecN focus preferentially towards the mid-cell position. RecN-GFP was absent in most mature heterocysts. Furthermore, our results showed that HetR, a central player in heterocyst development, was involved in the proper positioning and distribution of RecN-GFP. These results showed the dynamics of RecN in DSB repair and suggested a differential regulation of DNA DSB repair in vegetative cell and heterocysts. The absence of RecN in mature heterocysts is compatible with the terminal nature of these cells.

  14. Dynamics and Cell-Type Specificity of the DNA Double-Strand Break Repair Protein RecN in the Developmental Cyanobacterium Anabaena sp. Strain PCC 7120.

    Science.gov (United States)

    Hu, Sheng; Wang, Jinglan; Wang, Li; Zhang, Cheng-Cai; Chen, Wen-Li

    2015-01-01

    DNA replication and repair are two fundamental processes required in life proliferation and cellular defense and some common proteins are involved in both processes. The filamentous cyanobacterium Anabaena sp. strain PCC 7120 is capable of forming heterocysts for N2 fixation in the absence of a combined-nitrogen source. This developmental process is intimately linked to cell cycle control. In this study, we investigated the localization of the DNA double-strand break repair protein RecN during key cellular events, such as chromosome damaging, cell division, and heterocyst differentiation. Treatment by a drug causing DNA double-strand breaks (DSBs) induced reorganization of the RecN focus preferentially towards the mid-cell position. RecN-GFP was absent in most mature heterocysts. Furthermore, our results showed that HetR, a central player in heterocyst development, was involved in the proper positioning and distribution of RecN-GFP. These results showed the dynamics of RecN in DSB repair and suggested a differential regulation of DNA DSB repair in vegetative cell and heterocysts. The absence of RecN in mature heterocysts is compatible with the terminal nature of these cells.

  15. The alr2505 (osiS) gene from Anabaena sp. strain PCC7120 encodes a cysteine desulfurase induced by oxidative stress.

    Science.gov (United States)

    Ruiz, Marion; Bettache, Azzeddine; Janicki, Annick; Vinella, Daniel; Zhang, Cheng-Cai; Latifi, Amel

    2010-09-01

    NifS-like cysteine desulfurases are widespread enzymes involved in the mobilization of sulfur from cysteine. The genome of the filamentous diazotrophic cyanobacterium Anabaena PCC 7120 contains four open reading frames potentially encoding NifS-like proteins. One of them, alr2505, belongs to the pkn22 operon, which enables Anabaena to cope with oxidative stress. The Alr2505 protein was purified and found to share all the features characteristic of cysteine desufurases. This is the first NifS-like enzyme to be functionally characterized in this bacterium. On the basis of the transcriptional profiling of all nifS-like genes in Anabaena, it is concluded that alr2505 is the only cysteine desulfurase-encoding gene induced by oxidative stress. The function of Alr2505, which was termed OsiS, is discussed.

  16. NADPH-Thioredoxin Reductase C Mediates the Response to Oxidative Stress and Thermotolerance in the Cyanobacterium Anabaena sp. PCC7120.

    Science.gov (United States)

    Sánchez-Riego, Ana M; Mata-Cabana, Alejandro; Galmozzi, Carla V; Florencio, Francisco J

    2016-01-01

    NADPH-thioredoxin reductase C (NTRC) is a bimodular enzyme composed of an NADPH-thioredoxin reductase and a thiioredoxin domain extension in the same protein. In plants, NTRC has been described to be involved in the protection of the chloroplast against oxidative stress damage through reduction of the 2-Cys peroxiredoxin (2-Cys Prx) as well as through other functions related to redox enzyme regulation. In cyanobacteria, the Anabaena NTRC has been characterized in vitro, however, nothing was known about its in vivo function. In order to study that, we have generated the first knockout mutant strain (ΔntrC), apart from the previously described in Arabidopsis. Detailed characterization of this strain reveals a differential sensitivity to oxidative stress treatments with respect to the wild-type Anabaena strain, including a higher level of ROS (reactive oxygen species) in normal growth conditions. In the mutant strain, different oxidative stress treatments such as hydrogen peroxide, methyl-viologen or high light irradiance provoke an increase in the expression of genes related to ROS detoxification, including AnNTRC and peroxiredoxin genes, with a concomitant increase in the amount of AnNTRC and 2-Cys Prx. Moreover, the role of AnNTRC in the antioxidant response is confirmed by the observation of a pronounced overoxidation of the 2-Cys Prx and a time-delay recovery of the reduced form of this protein upon oxidative stress treatments. Our results suggest the participation of this enzyme in the peroxide detoxification in Anabaena. In addition, we describe the role of Anabaena NTRC in thermotolerance, by the appearance of high molecular mass AnNTRC complexes, showing that the mutant strain is more sensitive to high temperature treatments.

  17. NADPH-thioredoxin reductase C mediates the response to oxidative stress and thermotolerance in the cyanobacterium Anabaena sp. PCC7120.

    Directory of Open Access Journals (Sweden)

    ANA MARÍA SÁNCHEZ-RIEGO

    2016-08-01

    Full Text Available NTRC (NADPH-thioredoxin reductase C is a bimodular enzyme composed of an NADPH-thioredoxin reductase and a thioredoxin domain extension in the same protein. In plants, NTRC has been described to be involved in the protection of the chloroplast against oxidative stress damage through reduction of the 2-Cys peroxiredoxin (2-Cys Prx as well as through other functions related to redox enzyme regulation. In cyanobacteria, the Anabaena NTRC has been characterized in vitro, however nothing was known about its in vivo function. In order to study that, we have generated the first knockout mutant strain (∆ntrC, apart from the previously described in Arabidopsis. Detailed characterization of this strain reveals a differential sensitivity to oxidative stress treatments with respect to the wild-type Anabaena strain, including a higher level of ROS (reactive oxygen species in normal growth conditions. In the mutant strain, different oxidative stress treatments such as hydrogen peroxide, methyl-viologen or high light irradiance provoke an increase in the expression of genes related to ROS detoxification, including AnNTRC and peroxiredoxin genes, with a concomitant increase in the amount of AnNTRC and 2-Cys Prx. Moreover, the role of AnNTRC in the antioxidant response is confirmed by the observation of a pronounced overoxidation of the 2-Cys Prx and a time-delay recovery of the reduced form of this protein upon oxidative stress treatments. Our results suggest the participation of this enzyme in the peroxide detoxification in Anabaena. In addition, we describe the role of Anabaena NTRC in thermotolerance, by the appearance of high molecular mass AnNTRC complexes, showing that the mutant strain is more sensitive to high temperature treatments.

  18. Transcriptional dynamics of developmental genes assessed with an FMN-dependent fluorophore in mature heterocysts of Anabaena sp. strain PCC 7120.

    Science.gov (United States)

    Videau, Patrick; Oshiro, Reid T; Cozy, Loralyn M; Callahan, Sean M

    2014-09-01

    Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that differentiates nitrogen-fixing heterocysts when available combined nitrogen is limiting. Growth under diazotrophic conditions results in a mixture of 'new' (recently differentiated) and 'old' (mature) heterocysts. The microoxic environment present in heterocysts makes the interpretation of gene expression using oxygen-dependent fluorophores, including GFP, difficult. The work presented here evaluates the transcriptional dynamics of three developmental genes in mature heterocysts utilizing EcFbFP, a flavin mononucleotide-dependent fluorophore, as the reporter. Expression of both GFP and EcFbFP from the heterologous petE promoter showed that, although GFP and EcFbFP fluoresced in both vegetative cells and new heterocysts, only EcFbFP fluoresced in old heterocysts. A transcriptional fusion of EcFbFP to the late-stage heterocyst-specific nifB promoter displayed continued expression beyond the cessation of GFP fluorescence in heterocysts. Promoter fusions of the master regulator of differentiation, hetR, and its inhibitors, patS and hetN, to GFP and EcFbFP were visualized to determine their role(s) in heterocyst function after morphogenesis. The expression of hetR and hetN was found to persist beyond the completion of development in most heterocysts, whereas patS expression ceased. These data are consistent with a model of heterocyst patterning in which patS is involved in de novo pattern formation, hetN is required for pattern maintenance, and hetR is needed for all stages of development.

  19. NrrA directly regulates expression of the fraF gene and antisense RNAs for fraE in the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120.

    Science.gov (United States)

    Ehira, Shigeki; Ohmori, Masayuki

    2014-05-01

    The heterocystous cyanobacterium Anabaena sp. strain PCC 7120 grows as linear multicellular filaments that can contain hundreds of cells. Heterocysts, which are specialized cells for nitrogen fixation, are regularly intercalated among photosynthetic vegetative cells, and these cells are metabolically dependent on each other. Thus, multicellularity is essential for diazotrophic growth of heterocystous cyanobacteria. In Anabaena sp. strain PCC 7120, the fraF gene, which is required to limit filament length, is induced by nitrogen deprivation. The fraF transcripts extend to the fraE gene, which lies on the opposite DNA strand and could possess dual functionality, mRNAs for fraF and antisense RNAs for fraE. In the present study, we found that NrrA, a nitrogen-regulated response regulator, directly regulated expression of fraF. Induction of fraF by nitrogen deprivation was abolished by the nrrA disruption. NrrA specifically bound to the promoter region of fraF, and recognized an inverted repeat sequence. Thus, it is concluded that NrrA controls expression of mRNAs for fraF and antisense RNAs for fraE in response to nitrogen deprivation.

  20. N-terminal processing of membrane-targeted MnSOD and formation of multiple active superoxide dismutase dimers in the nitrogen-fixing cyanobacterium Anabaena sp. strain PCC7120.

    Science.gov (United States)

    Raghavan, Prashanth S; Rajaram, Hema; Apte, Shree K

    2013-10-01

    Anabaena sp. strain PCC7120 expresses a 30 kDa manganese-dependent superoxide dismutase (MnSOD) comprising a hydrophobic region (signal peptide + linker peptide) attached to a catalytic unit. Bioinformatics predicted cleavage of the signal peptide at (25)CQPQ by signal peptidase and of the linker peptide by an Arg-C-like protease at the Arg52/Arg59 residue. The three predicted forms of MnSOD were immunodetected in Anabaena, with the 30 kDa MnSOD found exclusively in the membrane and the shorter 27 and 24 kDa forms found both in the membrane and soluble fractions. The corresponding sodA gene was truncated for (a) the first eight residues, or, (b) the signal peptide, or (c) the entire hydrophobic region, or (d) the Arg52/Arg59 residues were modified to serine. Overexpression of these MnSOD variants in recombinant Anabaena strains revealed that (a) the 30 kDa membrane-targeted MnSOD was cleaved by membrane-localized signal peptidase either during or after its transport through the membrane to release the 27 kDa form, either in the cytosol or in the periplasmic/thylakoid lumen, (b) the 27 kDa form was further cleaved to the 24 kDa form by Arg-C-like protease, both in the cytosol and in the periplasmic/thylakoid lumen, (c) deletion of signal peptide localized the MnSOD forms in the cytosol, and (d) alteration of the signal/linker peptide cleavage sites interfered with MnSOD localization and processing. Homo/heterodimerization of the 24 and 27 kDa forms of MnSOD and the cytosolic iron-dependent SOD results in multiple SOD activities, from a single MnSOD gene (sodA), in different cellular compartments of Anabaena.

  1. Membrane targeting of MnSOD is essential for oxidative stress tolerance of nitrogen-fixing cultures of Anabaena sp. strain PCC7120.

    Science.gov (United States)

    Raghavan, Prashanth S; Rajaram, Hema; Apte, Shree Kumar

    2015-07-01

    The nitrogen-fixing cyanobacterium, Anabaena PCC7120 encodes for a membrane-targeted 30 kDa Mn-superoxide dismutase (MnSOD) and a cytosolic FeSOD. The MnSOD is post-translationally processed to 27 and 24 kDa forms in the cytosol and periplasm/thylakoid lumen. The extent of cleavage of signal and linker peptides at the N-terminus is dependent on the availability of combined nitrogen during growth. While the 24 and 27 kDa forms are present in near equal proportions under nitrogen-fixing conditions, the 24 kDa form is predominant under nitrogen-supplemented conditions. Individual contribution of these forms of MnSOD to total oxidative stress tolerance was analysed using recombinant Anabaena strains overexpressing either different molecular forms of MnSOD or MnSOD defective in the cleavage of signal/linker peptide. Targeting of MnSOD to the membrane and subsequent cleavage to release both the 24 and 27 kDa forms was essential for oxidative stress tolerance under nitrogen-fixing conditions. On the other hand, the cleavage of linker peptide was absolutely essential and the release of cytosolic 24 kDa form of MnSOD was obligatory for developing oxidative stress tolerance under nitrogen-supplemented conditions. Thus, a single MnSOD caters to the reduction of superoxide radical in both cytosol and thylakoid lumen/periplasm irrespective of the N-status of growth by regulating its cleavage. This is the first report on the physiological advantage of membrane-targeting and processing of MnSOD in either bacteria or plants. The higher oxidative stress tolerance offered by the cytosolic form of MnSOD has possibly resulted in retention of only the cytosolic form in bacterial non-nitrogen-fixers during evolution.

  2. Relations between biomass and absorbency of cultured broth culturing recombinant Anabaena Sp.PCC7120%转基因鱼腥藻培养中培养液吸光度与生物量的关系

    Institute of Scientific and Technical Information of China (English)

    刘志伟; 郭勇; 张晨

    2001-01-01

    对转基因鱼腥藻Anabaena sp.PCC7120,培养液的吸光特性进行了研究,在可见光范围内,有5个吸收峰,波长分别为345nm、410nm、440nm、635nm、685nm,其中440nm是最大吸收波长.一定稀释度范围内,在各波长下,培养液中藻干重与吸光度均成正比,但不同培养基其干重-吸光度标准曲线不同,实验得到不同培养基的标准曲线,证明可以用比浊法测定转基因鱼腥藻培养过程的生物量.

  3. Exploring the size limit of protein diffusion through the periplasm in cyanobacterium Anabaena sp. PCC 7120 using the 13 kDa iLOV fluorescent protein.

    Science.gov (United States)

    Zhang, Li-Chen; Risoul, Véronique; Latifi, Amel; Christie, John M; Zhang, Cheng-Cai

    2013-09-01

    In the filamentous heterocyst-forming cyanobacterium Anabaena PCC 7120, vegetative cells and heterocysts are interdependent on each other and engaged in exchanges of metabolites for survival when grown under diazotrophic conditions. In this organism, the periplasm appears to be continuous along each filament, with a shared outer membrane; however, barriers exist preventing free diffusion of the fluorescent protein GFP (27 kDa) targeted into the periplasmic space. Here we expressed a smaller fluorescent protein iLOV (≈ 13 kDa) fused to the All3333 (a putative homologue of NrtA) signal sequence corresponding to those recognized by the TAT protein translocation system, which exports iLOV to the periplasm of either heterocysts or vegetative cells. Fluorescence microscopy and immunoblot analysis indicated that the iLOV protein is translocated into the periplasm of the producing cell and properly processed, but does not diffuse to neighboring cells via the periplasm. Thus, periplasmic barriers appear to block diffusion of molecules with a size of 13 kDa, the minimum size tested thus far. Assuming that the physical barrier is the peptidoglycan sacculus, its pores might allow diffusion of molecules within the size range between the PatS pentapeptide and iLOV, thus between 0.53 kDa and 13 kDa.

  4. Evidence that the hanA gene coding for HU protein is essential for heterocyst differentiation in, and cyanophage A-4(L) sensitivity of, Anabaena sp. strain PCC 7120.

    Science.gov (United States)

    Khudyakov, I; Wolk, C P

    1996-06-01

    The highly pleiotropic, transposon-generated mutant AB22 of Anabaena sp. strain PCC 7120 exhibits slow growth, altered pigmentation, cellular fragility, resistance to phage A-4(L), and the inability to differentiate heterocysts. Reconstruction of the transposon mutation in the wild-type strain reproduced the phenotype of the original mutant. Sequencing of the flanking DNA showed that the transposon had inserted at the beginning of a gene, which we call hanA, that encodes Anabaena HU protein (R. Nagaraja and R. Haselkorn, Biochimie 76:1082-1089, 1994). Mapping of the transposon insertion by pulsed-field gel electrophoresis showed that hanA is located at ca. 4.76 Mb on the physical map of the chromosome and is transcribed clockwise. Repeated subculturing of AB22 resulted in improved growth and loss of filament fragmentation, presumably because of one or more compensatory mutations; however, the mutant retained its A-4(L)r Het- phenotype. The mutation in strain AB22 could be complemented by a fragment of wild-type DNA bearing hanA as its only open reading frame.

  5. Mutation of sepJ reduces the intercellular signal range of a hetN-dependent paracrine signal, but not of a patS-dependent signal, in the filamentous cyanobacterium Anabaena sp. strain PCC 7120.

    Science.gov (United States)

    Rivers, Orion S; Videau, Patrick; Callahan, Sean M

    2014-12-01

    Formation and maintenance of a periodic pattern of nitrogen-fixing cells called heterocysts by the filamentous cyanobacterium Anabaena sp. strain PCC 7120 is dependent on regulators encoded by patS and hetN. In this study, genetic mosaic filaments that consisted of cells engineered to produce one of the developmental regulators flanked by target cells capable of reporting the activity of the developmental regulator were used to investigate the intercellular movement of patS- and hetN-dependent activity. We provide evidence that hetN encodes a paracrine signal with a signal range of several cells. The signal that moved between cells did not include the C-terminus of the annotated HetN protein as indicated by similar signal ranges from source cells expressing either hetN-YFP or hetN alone, despite a lack of intercellular exchange of the HetN-YFP fusion protein. Deletion of sepJ, which has been shown to encode a component of intercellular channels, caused a significant decrease in the signal range of hetN expressed from source cells but not of patS. These results are consistent with symplastic transport of a paracrine hetN-dependent signal between vegetative cells of Anabaena.

  6. Expression of Mouse MT- Ⅰ as a Fusion Protein in Anabaena sp. PCC 7120%小鼠金属硫蛋白-Ⅰ在鱼腥藻7120中的融合表达及其纯化

    Institute of Scientific and Technical Information of China (English)

    周杰; 郝福英; 施定基; 俞梅敏; 茹炳根

    2003-01-01

    To produce mouse metallothionein- Ⅰ (mMT- Ⅰ ) in cyanobacterium Anabaena sp. PCC 7120, a novel Escherichia coli-cyanobacterium shuttle fusion expression vector, pKG-MT, was constructed. Via this vector, mMT- Ⅰ cDNA which was fused with a carboxyl terminal extension of the 26 kD glutathione-S-transferase (GST) containing a thrombin specific site was expressed in Anabaena under the control of tac promoter.SDS-polyacrylamid gel electrophoresis (SDS-PAGE) showed that the fusion protein GST-MT was expressed in the transgenic Anabaena sp. PCC 7120 after induction with isopropylthio-β-D-galactoside (IPTG). Glutatione-S-transferase metallothionein (GST-MT) was purified from the crude extracts by affinity chromatography on immobilized glutathione and mMT- Ⅰ was obtained by digesting the fusion protein with thrombin on column and gel filtration on Sephadex G-50. SDS-PAGE demonstrated that the purified mMT-Ⅰ was the desired protein.The result of ELISA for the purified mMT-Ⅰ showed that the recovery of mMT-Ⅰ from the transgenic cyanobacterium was about 0.6 mg/g fresh weight. According to the data of atomic absorption assay, metalbinding activity of the purified mMT- Ⅰ was almost the same as that of wild type MT.%为了提高小鼠金属硫蛋白-Ⅰ(mMT-Ⅰ)在鱼腥藻7120(Anabaena sp.PCC 7120)中的表达量、便于表达产物的分离纯化,构建了新的穿梭融合表达载体pKG-MT.通过pKG-MT,mMT-Ⅰ cDNA在tac启动子的调控下,以与谷胱甘肽转硫酶(GST)C-末端相融合(GST-MT)的形式在鱼藻中表达.SDS-PAGE结果显示在异丙基硫代-β-D-半乳糖苷(IPTG)诱导下GST-MT在鱼腥藻中表达.经谷胱甘肽亲合层析,从转基因藻中分离、纯化得到GST-MT.利用GSTC-末端的凝血酶酶切位点,用凝血酶对GST-MT进行柱上酶切,经Sephadex GS0除去凝血酶得到mMT-Ⅰ.SDS-PAGE表明纯化得到所要的目标产物;ELISA测定结果显示从每克转基因藻(鲜重)中可纯化得到0.9 mg mMT-Ⅰ;原子吸

  7. Production of cyanopeptolins, anabaenopeptins, and microcystins by the harmful cyanobacteria Anabaena 90 and Microcystis PCC 7806

    NARCIS (Netherlands)

    L. Tonk; M. Welker; J. Huisman; P.M. Visser

    2009-01-01

    This study investigated the effects of light intensity, temperature, and phosphorus limitation on the peptide production of the cyanobacteria Microcystis PCC 7806 and Anabaena 90. Microcystis PCC 7806 produced two microcystin variants and three cyanopeptolins, whereas Anabaena 90 produced four micro

  8. A Novel Aldo-Keto Reductase (AKR17A1) of Anabaena sp. PCC 7120 Degrades the Rice Field Herbicide Butachlor and Confers Tolerance to Abiotic Stresses in E. coli.

    Science.gov (United States)

    Agrawal, Chhavi; Sen, Sonia; Yadav, Shivam; Rai, Shweta; Rai, Lal Chand

    2015-01-01

    Present study deals with the identification of a novel aldo/keto reductase, AKR17A1 from Anabaena sp. PCC7120 and adds on as 17th family of AKR superfamily drawn from a wide variety of organisms. AKR17A1 shares many characteristics of a typical AKR such as- (i) conferring tolerance to multiple stresses like heat, UV-B, and cadmium, (ii) excellent activity towards known AKR substrates (isatin and 2-nitrobenzaldehyde), and (iii) obligate dependence on NADPH as a cofactor for enzyme activity. The most novel attribute of AKR17A1, first reported in this study, is its capability to metabolize butachlor, a persistent rice field herbicide that adversely affects agro-ecosystem and non-target organisms. The AKR17A1 catalyzed- degradation of butachlor resulted into formation of 1,2-benzene dicarboxylic acid and 2,6 bis (1,1, dimethylethyl) 4,-methyl phenol as the major products confirmed by GC-MS analysis.

  9. A Novel Aldo-Keto Reductase (AKR17A1 of Anabaena sp. PCC 7120 Degrades the Rice Field Herbicide Butachlor and Confers Tolerance to Abiotic Stresses in E. coli.

    Directory of Open Access Journals (Sweden)

    Chhavi Agrawal

    Full Text Available Present study deals with the identification of a novel aldo/keto reductase, AKR17A1 from Anabaena sp. PCC7120 and adds on as 17th family of AKR superfamily drawn from a wide variety of organisms. AKR17A1 shares many characteristics of a typical AKR such as- (i conferring tolerance to multiple stresses like heat, UV-B, and cadmium, (ii excellent activity towards known AKR substrates (isatin and 2-nitrobenzaldehyde, and (iii obligate dependence on NADPH as a cofactor for enzyme activity. The most novel attribute of AKR17A1, first reported in this study, is its capability to metabolize butachlor, a persistent rice field herbicide that adversely affects agro-ecosystem and non-target organisms. The AKR17A1 catalyzed- degradation of butachlor resulted into formation of 1,2-benzene dicarboxylic acid and 2,6 bis (1,1, dimethylethyl 4,-methyl phenol as the major products confirmed by GC-MS analysis.

  10. Effects of environment factors on the culture of recombinant Anabaena sp. PCC7120%环境因子对转基因鱼腥藻培养的影响

    Institute of Scientific and Technical Information of China (English)

    张晨; 刘志伟; 郭勇

    2002-01-01

    摇瓶中对转TNF-α基因鱼腥藻7120(Anabaena sp.PCC7120,pDC-TNF)混合培养条件进行了研究,在含蔗糖9 g/L,NaNO3 2.25 g/L的BG-11培养基混合培养时,得到最适培养条件接种量5%,光照强度为1000Lux,光/暗周期(光照时间/黑暗时间)12h/12h,温度25~30℃,自然初始pH值,100mL摇瓶装液量40mL,转基因鱼腥藻15d生物量可达到3g/L以上,可溶性蛋白含量接近30%,TNF表达水平大于22%,与自养相比,生物量增加82.06%,表达水平提高38.79%.证明混合营养型培养是转rhTNF-α基因鱼腥藻7120实现高密度、高表达培养的途径.

  11. FurA from Anabaena PCC 7120: New insights on its regulation and the interaction with DNA

    Science.gov (United States)

    Hernández, J. A.; López-Gomollón, S.; Pellicer, S.; Martín, B.; Sevilla, E.; Bes, M. T.; Peleato, M. L.; Fillat, M. F.

    2006-08-01

    Fur (ferric uptake regulator) proteins are global regulatory proteins involved in the maintenance of iron homeostasis. They recognize specific DNA sequences denoted iron boxes. It is assumed that Fur proteins act as classical repressors. Under iron-rich conditions, Fur dimers complexed with ferrous ions bind to iron boxes, preventing transcription. In addition to iron homeostasis, Fur proteins control the concerted response to oxidative and acidic stresses in heterotrophic prokaryotes. Our group studies the interaction between Fur proteins and target DNA sequences. Moreover, the regulation of FurA in the nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120, whose genome codes for three fur homologues has been investigated. We present an overview about the different factors involved in the regulation of FurA and analyze the parameters that influence FurA-DNA interaction in the cyanobacterium Anabaena PCC 7120.

  12. A novel alkyl hydroperoxidase (AhpD) of Anabaena PCC7120 confers abiotic stress tolerance in Escherichia coli.

    Science.gov (United States)

    Shrivastava, Alok Kumar; Singh, Shilpi; Singh, Prashant Kumar; Pandey, Sarita; Rai, L C

    2015-01-01

    In silico analysis together with cloning, molecular characterization and heterologous expression reports that the hypothetical protein All5371 of Anabaena sp. PCC7120 is a novel hydroperoxide scavenging protein similar to AhpD of bacteria. The presence of E(X)11CX HC(X)3H motif in All5371 confers peroxidase activity and closeness to bacterial AhpD which is also reflected by its highest 3D structure homology with Rhodospirillum rubrum AhpD. Heterologous expression of all5371 complimented for ahpC and conferred resistance in MJF178 strain (ahpCF::Km) of Escherichia coli. All5371 reduced the organic peroxide more efficiently than inorganic peroxide and the recombinant E. coli strain following exposure to H2O2, CdCl2, CuCl2, heat, UV-B and carbofuron registered increased growth over wild-type and mutant E. coli transformed with empty vector. Appreciable expression of all5371 in Anabaena sp. PCC7120 as measured by qRT-PCR under selected stresses and their tolerance against H2O2, tBOOH, CuOOH and menadione attested its role in stress tolerance. In view of the above, All5371 of Anabaena PCC7120 emerged as a new hydroperoxide detoxifying protein.

  13. 蓝细菌鱼腥藻7120混合营养培养的生长和生理特征%Growth and Physiological Features of Cyanobacterium Anabaena sp.Strain PCC 7120 in a Glucose-Mixotrophic Culture

    Institute of Scientific and Technical Information of China (English)

    喻国策; 施定基; 蔡昭铃; 丛威; 欧阳藩

    2011-01-01

    Mixotrophic growth is one potential mode for mass culture of microalgae and cyanobacteria particularly suitable for the production of high value bioactive compounds and fine chemicals. The typical heterocystous cyanobacterium Anabaena sp. PCC 7120 was grown in the presence of exogenous glucose in light. Glucose improved the cell growth evidently, the maximal specific growth rate under mixotrophic condition (0.38 d-1) being 1.6-fold of that of photoautotrophic growth. Mixotrophy caused a variation in cellular pigment composition, increasing the content of chlorophyll a and decreasing the contents of carotenoid and phycobiliprotein relative to chlorophyll a. Fluorescence emission from photosystem Ⅱ (PSⅡ) relative to photosystem Ⅰ was enhanced in mixotrophic cells, implying an increased energy distribution in PSII. Glucokinase (EC 2.7.1.2) activity was further induced in the presence of glucose. The mixotrophic culture was scaled up in a 15 L airlift photobioreactor equipped with an inner and an outer light source. A modified Monod model incorporating the specific growth rate and the average light intensity in the reactor was developed to describe cell growth appropriately. The understanding of mixotrophic growth and relevant physiological features ofAnabaena sp. PCC 7120 would be meaningful for cultivation and exploitation of this important cyanobacterial strain.

  14. Fluorapatite as Inorganic Phosphate Source for the Cyanobacterium Anabaena PCC 7120

    Science.gov (United States)

    Schaperdoth, I.; Brantley, S.

    2003-12-01

    We investigated the hypothesis that the cyanobacterium Anabaena PCC 7120 is able to use fluorapatite (FAP) as sole phosphate source for growth. In the experimental setup the dissolution of FAP was tested in a phosphate free growth medium in the presence and absence of the Anabaena, as well as the cell free supernatant of an Anabaena culture. The results were compared with that of an Anabaena culture grown without fluorapatite. Parameters measured were pH, dissolved P and Ca, as well as cell density. The FAP grains were analyzed using SEM and XPS. Additionally, the differential expression of secreted proteins in cultures with and without dissolved phosphate was examined. P-limited Anabaena cultures tend to aggregate and in the presence of FAP the cells attached themselves to the mineral grains. The cultures benefit from the presence of FAP. The cells have a very effective P-uptake system that is able to take up dissolved phosphate very efficiently and draw the concentrations down to very low levels. Furthermore, the SEM analysis of FAP showed an etching of the mineral grains in the samples from the Anabaena cultures. The mechanism of apatite dissolution with and without Anabaena will be discussed in terms of these experimental observations.

  15. The rice field cyanobacteria Anabaena azotica and Anabaena sp. CH1 express vanadium-dependent nitrogenase

    NARCIS (Netherlands)

    Boison, G.; Steingen, C.; Stal, L.J.; Bothe, H.

    2006-01-01

    Anabaena azotica FACHB-118 and Anabaena sp. CH1, heterocystous cyanobacteria isolated from Chinese and Taiwanese rice fields, expressed vanadium-containing nitrogenase when under molybdenum deficiency. This is the second direct observation of an alternative nitrogenase in cyanobacteria. The vanadium

  16. Enduring toxicity of transgenic Anabaena PCC 7120 expressing mosquito larvicidal genes from Bacillus thuringiensis ssp. israelensis.

    Science.gov (United States)

    Manasherob, Robert; Otieno-Ayayo, Zachariah Ngalo; Ben-Dov, Eitan; Miaskovsky, Rina; Boussiba, Sammy; Zaritsky, Arieh

    2003-10-01

    Persistence of biological control agents against mosquito larvae was tested under simulated field conditions. Mosquito larvicidal activity of transgenic Anabaena PCC 7120 expressing cry4Aa, cry11Aa and p20 from Bacillus thuringiensis ssp. israelensis was greater than B. thuringiensis ssp. israelensis primary powder (fun 89C06D) or wettable powder (WP) (Bactimos products) when either mixed with silt or exposed to sunlight outdoors. Reduction of Bactimos primary powder toxicity was at least 10-fold higher than Anabaena's after mixing with silt. In outdoors experiments, Bactimos WP remained toxic (over 30% mortality of 3rd instar Aedes aegypti larvae) for 2-4 days only, while transgenic Anabaena's toxicity endured 8-21 days.

  17. Complete Genome Sequence of the Cyanobacterium Anabaena sp. 33047

    Science.gov (United States)

    2016-01-01

    This study presents the complete nucleotide sequence of Anabaena sp. ATCC 33047 (Anabaena CA), a filamentous, nitrogen-fixing marine cyanobacterium, which under salt stress conditions accumulates sucrose internally. The elucidation of the genome will contribute to the understanding of cyanobacterial diversity. PMID:27516507

  18. TNF_α基因在鱼腥藻7120中的表达及其产物的亲和层析纯化%Expression of TNF_α Gene in Anabaena sp. PCC 7120 and Purification of Its Product by Affinity Chromatography

    Institute of Scientific and Technical Information of China (English)

    施定基; 李振甲; 叶欣; 钟晖; 蔡以滢; 邵宁; 彭国宏; 董晓军; 王春梅; 欧阳叶新

    2001-01-01

    The effects of N (NaNO3) and C (NaAc) source in medium on the expression of tumor necrosis factor_α (TNF_α) gene in transgenic Anabaena sp. PCC 7120 were compared. The data showed that N source stabilized the expression of foreign protein and C source altered the synthesis of cell walls. Comparing several methods for breaking the cells, supersonic was able to extract TNF_α better than others. For purification of TNF_α, transgenic Anabaena cells were broken, the extracts were precipitated with ammonia sulfate, and the impure TNF_α was eluted from DEAE ion exchange chromatography. Electrophoresis (PAGE_SDS) showed a single band at 17 kD position.%用转入TNF_α基因并稳定表达了4年多的丝状体蓝藻——鱼腥藻7120 (Anabaena sp. PCC 7120),研究比较了在培养液中氮源(NaNO3)和碳源(NaAc)对转基因藻生长和TNF_α基因的不同影响。氮源能稳定外源蛋白的表达,而碳源则影响细胞壁的合成。通过比较几种不同的破碎细胞的方法, 发现超声破碎得到的可溶性总蛋白含量和TNF_α含量均要比冻融法高出1倍左右,经过细胞破碎、硫酸铵分级沉淀、常压离子交换液相层析后,除去杂蛋白及大量容易堵柱的糖类等物质,最后通过亲和柱层析,分离出了纯的目标蛋白——重组肿瘤坏死因子(TNF_α)。经凝胶电泳鉴定为单一的谱带,分子量为17 kD。

  19. In silico and wet-lab study revealed cadmium is the potent inhibitor of HupL in Anabaena sp. PC C 7120.

    Science.gov (United States)

    Singh, Shilpi; Shrivastava, Alok Kumar

    2016-01-01

    The hupL of Anabaena sp. PCC 7120 encodes the large subunit of uptake hydrogenase found in all diazotrophic cyanobacteria and boosts up the nitrogen-fixing potential by catalyzing the removal of the molecular hydrogen produced as a by-product of dinitrogen fixation. Bioinformatics analysis revealed that HupL from Anabaena sp. PCC7120 is a 60.2 kDa, thermostable, glycine-rich protein having highest structural similarity with NiFeSe hydrogenase of Desulfomicrobium baculatumis. Toxicity of selected abiotic stresses like arsenic, cadmium, copper, and salt with HupL was further reconciled by wet-lab approaches like qRT-PCR, hydrogenase and nitrogenase activity assay as hydrogenases unintendedly affect the nitrogenase activity in Anabaena. Down-regulated transcript along with highly inhibited hydrogenase and nitrogenase activities under cadmium stress revealed that cadmium is a potent inhibitor of hydrogenases in Anabaena which indirectly affects its nitrogen-fixing capabilities

  20. Taxonomy Icon Data: Synechocystis sp.PCC 6803 [Taxonomy Icon

    Lifescience Database Archive (English)

    Full Text Available Synechocystis_sp_PCC_6803_NL.png Synechocystis_sp_PCC_6803_S.png Synechocystis_sp_PCC_6803_NS.png http://biosciencedbc.jp/taxonomy..._icon/icon.cgi?i=Synechocystis+sp%2ePCC+6803&t=L http://biosciencedbc.jp/taxonomy_ico...n/icon.cgi?i=Synechocystis+sp%2ePCC+6803&t=NL http://biosciencedbc.jp/taxonomy_ic...on/icon.cgi?i=Synechocystis+sp%2ePCC+6803&t=S http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Synechocystis...+sp%2ePCC+6803&t=NS http://togodb.biosciencedbc.jp/togodb/view/taxonomy_icon_comment_en?species_id=69 ...

  1. Environmental and nutritional factors affecting geosmin synthesis by Anabaena sp.

    Science.gov (United States)

    Saadoun, I M; Schrader, K K; Blevins, W T

    2001-04-01

    A cyanobacterium isolated from a source-water reservoir during a spring odor and taste episode and identified as Anabaena sp. consistently produced geosmin during laboratory culture on modified BG-11 liquid medium. Maximal geosmin/biomass occurred at 20 degrees C and a light intensity of 17 microE/m2/s; geosmin/chla values directly correlated with increasing light intensity (r2 = 0.95, P geosmin synthesis; at 17 microE/m2/s, increasing temperature stimulates chla production (to 25 degrees C) while repressing geosmin synthesis (above 20 degrees C). Nutritional factors promoting biomass, chla, and geosmin synthesis by Anabaena sp. were also investigated. For cultures grown at 17 microE/m2/s and 20 degrees C for 20 days, both ammonium-N and nitrate-N generally enhanced the growth of Anabaena sp. Nitrate-N promoted more chla production (r2 = 0.99) than ammonium-N. Geosmin synthesis was directly correlated with ammonium-N concentrations (r2 = 0.89), with low nitrate-N (123.5 micrograms/l) favoring maximal geosmin production (2.8 micrograms/l). Increasing nitrate-N concentrations promoted a three-fold increase in chla content with geosmin synthesis decreased by two-fold. Geosmin/mg biomass was directly related to ammonium-N concentration; high nitrate-N levels suppressed geosmin production. No geosmin was detected at or below 118 micrograms phosphate-phosphorus/l. Geosmin, dry weight biomass, and chla production were correlated with increasing phosphorus (P) concentration (r2 = 0.76, 0.96 and 0.98, respectively). No geosmin was detected when copper was present in growth media at or above 6.92 micrograms Cu2+/l (CuSO4.5H2O). Dry weight biomass and chla production were negatively correlated with Cu2+ ion concentrations.

  2. The susceptibility of five African Anopheles species to Anabaena PCC 7120 expressing Bacillus thuringiensis subsp. israelensis mosquitocidal cry genes

    Directory of Open Access Journals (Sweden)

    Ketseoglou Irene

    2012-10-01

    Full Text Available Abstract Background Malaria, one of the leading causes of death in Africa, is transmitted by the bite of an infected female Anopheles mosquito. Problems associated with the development of resistance to chemical insecticides and concerns about the non-target effects and persistence of chemical insecticides have prompted the development of environmentally friendly mosquito control agents. The aim of this study was to evaluate the larvicidal activity of a genetically engineered cyanobacterium, Anabaena PCC 7120#11, against five African Anopheles species in laboratory bioassays. Findings There were significant differences in the susceptibility of the anopheline species to PCC 7120#11. The ranking of the larvicidal activity of PCC 7120#11 against species in the An. gambiae complex was: An. merus An. arabiensis An. gambiae An. quadriannulatus, where 50. The LC50 of PCC 7120#11 against the important malaria vectors An. gambiae and An. arabiensis was 12.3 × 105 cells/ml and 8.10 × 105 cells/ml, respectively. PCC 7120#11 was not effective against An. funestus, with less than 50% mortality obtained at concentrations as high as 3.20 × 107 cells/ml. Conclusions PCC 7120#11 exhibited good larvicidal activity against larvae of the An. gambiae complex, but relatively weak larvicidal activity against An. funestus. The study has highlighted the importance of evaluating a novel mosquitocidal agent against a range of malaria vectors so as to obtain a clear understanding of the agent’s spectrum of activity and potential as a vector control agent.

  3. Bioinformatics evidence for the transfer of mycosporine-like amino acid core (4-deoxygadusol) synthesizing gene from cyanobacteria to dinoflagellates and an attempt to mutate the same gene (YP_324358) in Anabaena variabilis PCC 7937.

    Science.gov (United States)

    Singh, Shailendra P; Häder, Donat-P; Sinha, Rajeshwar P

    2012-06-01

    We have identified a homologue of 4-deoxygadusol (core of mycosporine-like amino acids) synthesizing gene (ZP_05036788) from Synechococcus sp. PCC 7335 that was found to have additional functionally unknown N-terminal domain similar to homologues from dinoflagellates based on the ClustalW analysis. Phylogenetic analysis revealed that Synechococcus sp. (ZP_05036788) makes a clade together with dinoflagellates and was closest to the Oxyrrhis marina. This study shows for the first time that N-terminal additional sequences that possess upstream plastid targeting sequence in Heterocapsa triquetra and Karlodinium micrum were already evolved in cyanobacteria, and plastid targeting sequence were evolved later in dinoflagellates after divergence from chloroplast lacking Oxyrrhis marina. Thus, MAAs synthesizing genes were transferred from cyanobacteria to dinoflagellates and possibly Synechococcus sp. PCC 7335 acted as a donor during lateral gene transfer event. In addition, we also tried to mutate 4-deoxygadusol synthesizing gene (YP_324358) of Anabaena variabilis PCC 7937 by homologous recombination, however, all approaches to get complete segregation of the mutants from the wild-type were unsuccessful, showing the essentiality of YP_324358 for A. variabilis PCC 7937.

  4. The interaction of boron with glycolipids is required to increase tolerance to stresses in Anabaena PCC 7120.

    Science.gov (United States)

    Abreu, Isidro; Orús, Isabel; Bolaños, Luis; Bonilla, Ildefonso

    2014-10-01

    Boron (B) is an essential nutrient for heterocystous cyanobacteria growing under diazotrophic conditions. Under B-deficient conditions, the heterocyst envelope is highly disorganized, and the glycolipid layer is predominantly lost. Therefore, we examined whether B is implicated in the regulation of synthesis or processing and/or stability of glycolipids in Anabaena PCC 7120. RT-PCR analysis indicated that the expression of hglE was not significantly changed under B deficiency, suggesting that the synthesis of glycolipids during heterocyst formation was not compromised. In contrast, the overexpression of devB and hepA, encoding a glycolipid and a carbohydrate transporter, respectively, results in the instability of the envelope under B-deficient conditions. The capacity of borate to bind and stabilize molecules is considered the basis of any B biological function. Using a borate-binding-specific resin and thin layer chromatography, we detected the glycolipids that interact with B. Several heterocyst-specific glycolipids were detected as putative B ligands, suggesting a role for B in stabilizing the heterocyst envelope. Moreover, the glycolipids of Anabaena growing in non-diazotrophic conditions were also detected as putative B ligands. Although B is not essential for Anabaena under non-N2-fixing conditions, the presence of this micronutrient increased the tolerance of Anabaena to detergent treatment, salinity and hyperosmotic conditions. Taken together, the results of the present experiment suggest a beneficial role for B in environmental adaptation. Furthermore, we discuss the nutrient requirement for living organisms growing in nature and not under laboratory conditions.

  5. Nitrogen fixation (nif) genes of the cyanobacterium Anabaena species strain PCC 7120. The nifB-fdxN-nifS-nifU operon.

    Science.gov (United States)

    Mulligan, M E; Haselkorn, R

    1989-11-15

    A second nitrogen fixation (nif) operon in the cyanobacterium (blue-green alga) Anabaena (Nostoc) sp. strain PCC 7120 has been identified and sequenced. It is located just upstream of the nifHDK operon and consists of four genes in the order nifB, fdxN, nifS, and nifU. The three nif genes were identified on the basis of their similarity with the corresponding genes from other diazotrophs. The fourth gene, fdxN, codes for a bacterial type ferredoxin (Mulligan, M. E., Buikema, W. J., and Haselkorn, R. (1988) J. Bacteriol. 167, 4406-4410). The four genes are probably transcribed as a single operon, but are expressed at a lower level than the nifHDK operon, and only after a developmentally induced DNA rearrangement occurs that excises a 55-kilobase pair element from within the fdxN gene (Golden, J. W., Mulligan, M. E., and Haselkorn, R. (1987) Nature 327, 526-529; Golden, J. W., Carrasco, C. D., Mulligan, M. E., Schneider, G. J., and Haselkorn, R. (1988) J. Bacteriol. 170, 5034-5041). The promoter for the nifB operon was located by primer extension. Comparison of the nifB 5'-flanking sequence with the nifH 5'-flanking sequence did not reveal any consensus base pairs that would define a nif promoter for Anabaena. The operon contains two instances of 7-base pair directly repeated sequences: seven copies of the repeated sequence are found between the nifB and fdxN genes and six copies are found between the nifS and nifU genes. The function of these repeats is unknown.

  6. Purification, crystallization and preliminary crystallographic analysis of KatB, a manganese catalase from Anabaena PCC 7120.

    Science.gov (United States)

    Bihani, Subhash Chandra; Chakravarty, Dhiman; Ballal, Anand

    2013-11-01

    Catalases are enzymes that play an important role in the detoxification of hydrogen peroxide (H2O2) in aerobic organisms. Among catalases, haem-containing catalases are ubiquitously distributed and their enzymatic mechanism is very well understood. On the other hand, manganese catalases that contain a bimanganese core in the active site have been less well characterized and their mode of action is not fully understood. The genome of Anabaena PCC 7120 does not show the presence of a haem catalase-like gene; instead, two ORFs encoding manganese catalases (Mn-catalases) are present. Here, the crystallization and preliminary X-ray crystallographic analysis of KatB, one of the two Mn-catalases from Anabaena, are reported. KatB was crystallized using the hanging-drop vapour-diffusion method with PEG 400 as a precipitant and calcium acetate as an additive. Diffraction data were collected in-house on an Agilent SuperNova system using a microfocus sealed-tube X-ray source. The crystal diffracted to 2.2 Å resolution at 100 K. The tetragonal crystal belonged to space group P4(1)2(1)2 (or enantiomer), with unit-cell parameters a = b = 101.87, c = 138.86 Å. Preliminary X-ray diffraction analysis using the Matthews coefficient and self-rotation function suggests the presence of a trimer in the asymmetric unit.

  7. Peroxidation radical formation and regiospecificity of recombinated Anabaena sp. lipoxygenase and its effect on modifying wheat proteins.

    Science.gov (United States)

    Wang, Xiaoming; Lu, Fengxia; Zhang, Chong; Lu, Yingjian; Bie, Xiaomei; Ren, Di; Lu, Zhaoxin

    2014-02-19

    Peroxidation radical formation and the regiospecificity of recombinated lipoxygenase from Anabaena sp. PCC7120 (ana-rLOX) were characterized by using ESR and HPLC-MS. It was found that ana-rLOX oxygenated at the C-13 position of the substrate linoleic acid (LA); at C-13 and C-16 of α-linolenic acid (ALA); at C-9, C-12, and C-15 of arachidonic acid (AA); at C-12, C-15, and C-18 of eicosapentaenoic acid (EPA); and at C-14 and C-16 of docosahexaenoic acid (DHA), respectively. A total of 7, 14, 30, 28, and 18 radical adducts for LA, ALA, AA, EPA, and DHA were respectively identified by HPLC-MS. The functional characteristics of wheat protein, such as foaming capacity (FC), foam stability (FS), emulsifying activity index (EAI), emulsifying stability index (ESI), increased with enzymatic reactions. However, the average particle size of wheat proteins decreased with addition of ana-rLOX/LA. The ana-rLOX was also positivele effective in improving dough properties. These results provided clear evidence that ana-rLOX from Anabaena sp. could effectively improve the quality of wheat flour, which suggested that the enzyme could be applied as flour improver.

  8. Inactivation of a heterocyst-specific invertase indicates a principal role of sucrose catabolism in heterocysts of Anabaena sp.

    Science.gov (United States)

    López-Igual, Rocío; Flores, Enrique; Herrero, Antonia

    2010-10-01

    Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that carries out N(2) fixation in specialized cells called heterocysts, which exchange nutrients and regulators with the filament's vegetative cells that perform the photosynthetic fixation of CO(2). The Anabaena genome carries two genes coding for alkaline/neutral invertases, invA and invB. As shown by Northern analysis, both genes were expressed monocistronically and induced under nitrogen deprivation, although induction was stronger for invB than for invA. Whereas expression of an InvA-N-GFP fusion (green fluorescent protein [GFP] fused to the N terminus of the InvA protein [InvA-N]) was homogeneous along the cyanobacterial filament, consistent with the lack of dependence on HetR, expression of an InvB-N-GFP fusion upon combined nitrogen deprivation took place mainly in differentiating and mature heterocysts. In an hetR genetic background, the InvB-N-GFP fusion was strongly expressed all along the filament. An insertional mutant of invA could grow diazotrophically but was impaired in nifHDK induction and exhibited an increased frequency of heterocysts, suggesting a regulatory role of the invertase-mediated carbon flux in vegetative cells. In contrast, an invB mutant was strongly impaired in diazotrophic growth, showing a crucial role of sucrose catabolism mediated by the InvB invertase in the heterocysts.

  9. Proteomic analysis reveals contrasting stress response to uranium in two nitrogen-fixing Anabaena strains, differentially tolerant to uranium.

    Science.gov (United States)

    Panda, Bandita; Basu, Bhakti; Acharya, Celin; Rajaram, Hema; Apte, Shree Kumar

    2017-01-01

    Two strains of the nitrogen-fixing cyanobacterium Anabaena, native to Indian paddy fields, displayed differential sensitivity to exposure to uranyl carbonate at neutral pH. Anabaena sp. strain PCC 7120 and Anabaena sp. strain L-31 displayed 50% reduction in survival (LD50 dose), following 3h exposure to 75μM and 200μM uranyl carbonate, respectively. Uranium responsive proteome alterations were visualized by 2D gel electrophoresis, followed by protein identification by MALDI-ToF mass spectrometry. The two strains displayed significant differences in levels of proteins associated with photosynthesis, carbon metabolism, and oxidative stress alleviation, commensurate with their uranium tolerance. Higher uranium tolerance of Anabaena sp. strain L-31 could be attributed to sustained photosynthesis and carbon metabolism and superior oxidative stress defense, as compared to the uranium sensitive Anabaena sp. strain PCC 7120.

  10. Complete Genome Sequence of a Novel Strain of Cyanobacterium, Anabaena sp. 4-3

    Science.gov (United States)

    Sowa, Steven

    2016-01-01

    We report the complete nucleotide sequence of Anabaena sp. 4-3, an efficient producer of sucrose. It was isolated from salt flats near the University of Texas Marine Science Institute in Port Aransas, Texas. The genome may provide insight into the utilization of cyanobacteria as a source for biofuels. PMID:27540066

  11. The nuiA gene from Anabaena sp. encoding an inhibitor of the NucA sugar-non-specific nuclease.

    Science.gov (United States)

    Muro-Pastor, A M; Herrero, A; Flores, E

    1997-05-01

    Many filamentous, heterocyst-forming cyanobacteria express a sugar-non-specific nuclease of about 29 kDa that can be detected in DNA-containing SDS-PAGE gels. The nucA gene encoding this nuclease has previously been cloned from Anabaena sp. PCC 7120, sequenced and expressed in Escherichia coli. The NucA protein bears a putative signal peptide close to its N-terminal end and, in Anabaena cultures, is present in both the cells and the extracellular medium. Cell-free extracts of different cyanobacteria producing NucA-like nucleases exhibited an inhibitory activity on NucA. In Anabaena sp. PCC 7120, this inhibition was exerted by protein(s) or protein-containing molecule(s) that were heat resistant. Immediately downstream from the nucA gene, in the complementary strand, we have identified an open reading frame composed of 135 codons, that we have named nuiA, whose expression in E. coli conferred heat-resistant NucA-inhibitory activity to cell-free extracts. The NuiA protein was purified to homogeneity, and purified NuiA inhibited the nuclease activity of NucA. Sequences hybridizing with the nuiA gene have been found in all the tested cyanobacterial strains that express a NucA-like nuclease. Whereas the NucA protein is homologous to endonuclease G from vertebrates and to nucleases from Serratia marcescens and yeast, no protein homologous to NuiA was found in the available databases. Therefore, nuiA represents a novel gene encoding a nuclease inhibitor.

  12. Sodium Acetate Stimulates PHB Biosynthesis in Synechocystis sp. PCC 6803

    Institute of Scientific and Technical Information of China (English)

    吴桂芳; 鲍恬; 沈忠耀; 吴庆余

    2002-01-01

    Synechocystis sp. PCC 6803 cell growth and poly-β-hydroxybutyrate (PHB) biosynthesis were studied in the presence of sodium acetate (NaAc). For nitrogen-sufficient conditions, 15 -mmol/L NaAc improved the PHB content up to 9.9% (w/w) while for nitrogen-starved conditions, the PHB content was up to 15.2% (w/w). NaAc at levels below 20 -mmol/L promoted cell growth in the first six days, but the growth slowed on the seventh day when the NaAc concentration exceeded 15 -mmol/L. The PHB content in the final biomass reached 11.0% of the dry cellular weight in the presence of 20 -mmol/L NaAc. Two adjacent open reading frames (ORFs) in the genome of Synechocystis sp. PCC 6803, slr1993 and slr1994, were assigned to phbA and phbB, respectively, while the phbC gene was found to be far from these genes. This may account for the low expression of PHB in cyanobacteria.

  13. Physiological and proteomic analysis of salinity tolerance of the halotolerant cyanobacterium Anabaena sp.

    Science.gov (United States)

    Yadav, Ravindra Kumar; Thagela, Preeti; Tripathi, Keshawanand; Abraham, G

    2016-09-01

    The halotolerant cyanobacterium Anabaena sp was grown under NaCl concentration of 0, 170 and 515 mM and physiological and proteomic analysis was performed. At 515 mM NaCl the cyanobacterium showed reduced photosynthetic activities and significant increase in soluble sugar content, proline and SOD activity. On the other hand Anabaena sp grown at 170 mM NaCl showed optimal growth, photosynthetic activities and comparatively low soluble sugar content, proline accumulation and SOD activity. The intracellular Na(+) content of the cells increased both at 170 and 515 mM NaCl. In contrast, the K(+) content of the cyanobacterium Anabaena sp remained stable in response to growth at identical concentration of NaCl. While cells grown at 170 mM NaCl showed highest intracellular K(+)/Na(+) ratio, salinity level of 515 mM NaCl resulted in reduced ratio of K(+)/Na(+). Proteomic analysis revealed 50 salt-responsive proteins in the cyanobacterium Anabaena sp under salt treatment compared with control. Ten protein spots were subjected to MALDI-TOF-MS/MS analysis and the identified proteins are involved in photosynthesis, protein folding, cell organization and energy metabolism. Differential expression of proteins related to photosynthesis, energy metabolism was observed in Anabaena sp grown at 170 mM NaCl. At 170 mM NaCl increased expression of photosynthesis related proteins and effective osmotic adjustment through increased antioxidant enzymes and modulation of intracellular ions contributed to better salinity tolerance and optimal growth. On the contrary, increased intracellular Na(+) content coupled with down regulation of photosynthetic and energy related proteins resulted in reduced growth at 515 mM NaCl. Therefore reduced growth at 515 mM NaCl could be due to accumulation of Na(+) ions and requirement to maintain higher organic osmolytes and antioxidants which is energy intensive. The results thus show that the basis of salt tolerance is different when the

  14. Utilization of the cyanobacteria Anabaena sp CH1 in biological carbon dioxide mitigation processes

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, C.L.; Lee, C.M.; Chen, P.C. [Hungkuang University, Taichung (Taiwan)

    2011-05-15

    Before switching totally to alternative fuel stage, CO{sub 2} mitigation process has considered a transitional strategy for combustion of fossil fuels inevitably. In comparison to other CO{sub 2} mitigation options, such as oceanic or geologic injection, the biological photosynthetic process would present a far superior and sustainable solution under both environmental and social considerations. The utilization of the cyanobacteria Anabaena sp. CH1 in carbon dioxide mitigation processes is analyzed in our research. It was found that an original developed photobioreactor with internal light source exhibits high light utilization. Anabaena sp. CH1 demonstrates excellent CO{sub 2} tolerance even at 15% CO{sub 2} level. This enables flue gas from power plant to be directly introduced to Anabaena sp. CH1 culture. Double light intensity and increased 47% CO{sub 2} bubble retention time could enhance CO{sub 2} removal efficiencies by 79% and 67%, respectively. A maximum CO{sub 2} fixation rate of 1.01 g CO{sub 2} L{sup -1} day{sup -1} was measured experimentally.

  15. Identification and nitrogen regulation of the cyanase gene from the cyanobacteria Synechocystis sp. strain PCC 6803 and Synechococcus sp. strain PCC 7942.

    OpenAIRE

    Harano, Y; Suzuki, I.; Maeda, S; Kaneko, T.; Tabata, S; Omata, T

    1997-01-01

    An open reading frame (slr0899) on the genome of Synechocystis sp. strain PCC 6803 encodes a polypeptide of 149 amino acid residues, the sequence of which is 40% identical to that of cyanase from Escherichia coli. Introduction into a cyanase-deficient E. coli strain of a plasmid-borne slr0899 resulted in expression of low but significant activity of cyanase. Targeted interruption of a homolog of slr0899 from Synechococcus sp. strain PCC 7942, encoding a protein 77% identical to that encoded b...

  16. INFLUENCE OF HIGH LIGHT INTENSITY ON THE CELLS OF CYANOBACTERIA ANABAENA VARIABILIS SP. ATCC 29413

    Directory of Open Access Journals (Sweden)

    OPRIŞ SANDA

    2012-12-01

    Full Text Available In this article is presented the result of research regardind the effect of high light intensity on the cells of Anabaena variabilis sp. ATCC 29413, the main objective is to study the adaptation of photosynthetic apparatus to light stress. Samples were analyzed in the present of herbicide diuron (DCMU which blocks electron flow from photosystem II and without diuron. During treatment maximum fluorescence and photosystems efficiency are significantly reduced, reaching very low values compared with the blank, as a result of photoinhibition installation. Also by this treatment is shown the importance of the mechanisms by which cells detect the presence of light stress and react accordingly.

  17. Characterization and Optimization of Bioflocculant Exopolysaccharide Production by Cyanobacteria Nostoc sp. BTA97 and Anabaena sp. BTA990 in Culture Conditions.

    Science.gov (United States)

    Tiwari, Onkar Nath; Khangembam, Romi; Shamjetshabam, Minerva; Sharma, Aribam Subhalaxmi; Oinam, Gunapati; Brand, Jerry J

    2015-08-01

    Bioflocculant exopolysaccharide (EPS) production by 40 cyanobacterial strains during their photoautotrophic growth was investigated. Highest levels of EPS were produced by Nostoc sp. BTA97 and Anabaena sp. BTA990. EPS production was maximum during stationary growth phase, when nitrogenase activity was very low. Maximum EPS production occurred at pH 8.0 in the absence of any combined nitrogen source. The cyanobacterial EPS consisted of soluble protein and polysaccharide that included substantial amounts of neutral sugars and uronic acid. The EPS isolated from Anabaena sp. BTA990 and Nostoc sp. BTA97 demonstrated high flocculation capacity. There was a positive correlation between uronic acid content and flocculation activity. The flocculant bound a cationic dye, Alcian Blue, indicating it to be polyanionic. The 16S rRNA gene sequences for Nostoc sp. BTA97 and Anabaena sp. BTA990 were deposited at NCBI GenBank, and accession numbers were obtained as KJ830951 and KJ830948, respectively. The results of these experiments indicate that strains Anabaena sp. BTA990 and Nostoc sp. BTA97 are good candidates for the commercial production of EPS and might be utilized in industrial applications as an alternative to synthetic and abiotic flocculants.

  18. Utilization of the cyanobacteria Anabaena sp. ATCC 33047 in CO2 removal processes.

    Science.gov (United States)

    González López, C V; Acién Fernández, F G; Fernández Sevilla, J M; Sánchez Fernández, J F; Cerón García, M C; Molina Grima, E

    2009-12-01

    In this paper the utilization of the cyanobacteria Anabaena sp. in carbon dioxide removal processes is evaluated. For this, continuous cultures of this strain were performed at different dilution rates; alternatives for the recovery of the organic matter produced being also studied. A maximum CO(2) fixation rate of 1.45 g CO(2) L(-1) day(-1) was measured experimentally, but it can be increased up to 3.0 g CO(2) L(-1) day(-1) outdoors. The CO(2) is mainly transformed into exopolysaccharides, biomass representing one third of the total organic matter produced. Organic matter can be recovered by sedimentation with efficiencies higher than 90%, the velocity of sedimentation being 2.10(-4) s(-1). The major compounds were carbohydrates and proteins with productivities of 0.70 and 0.12 g L(-1) day(-1), respectively. The behaviour of the cultures of Anabaena sp. has been modelized, also the characteristics parameters requested to design separation units being reported. Finally, to valorizate the organic matter as biofertilizers and biofuels is proposed.

  19. Two-Component Signal Transduction Systems in the Cyanobacterium Synechocystis sp. PCC 6803

    Institute of Scientific and Technical Information of China (English)

    LIU Xingguo; HUANG Wei; WU Qingyu

    2006-01-01

    Two-component systems are signal transduction systems which enable bacteria to regulate cellular functions in response to changing environmental conditions. The unicellular Synechocystis sp. PCC 6803 has become a model organism for a range of biochemical and molecular biology studies aiming at investigating environmental stress response. The publication of the complete genome sequence of the cyanobacterium Synechocystis sp. PCC 6803 provided a tremendous stimulus for research in this field, and at least 80 open reading frames were identified as members of the two-component signal transduction systems in this single species of cyanobacteria. To date, functional roles have been determined for only a limited number of such proteins. This review summarizes our current knowledge about the two-component signal transduction systems in Synechocystis sp. PCC 6803 and describes recent achievements in elucidating the functional roles of these systems.

  20. BIOTRANSFORMATION OF 2,4,6-TRINITROTOLUENE IN A CONTINUOUS-FLOW ANABAENA SP. SYSTEM. (R825513C013)

    Science.gov (United States)

    Reductive transformation of 2,4,6-trinitrotoluene (TNT) was observed in a continuous-flow system of Anabaena sp. operated for 33 d with a 5.7 d hydraulic retention time and a range of influent TNT concentrations of 1–58 mg/l. The TNT removal effici...

  1. Molecular investigation of the radiation resistance of edible cyanobacterium Arthrospira sp. PCC 8005

    OpenAIRE

    2015-01-01

    The aim of this work was to characterize in detail the response of Arthrospira to ionizing radiation, to better understand its radiation resistance capacity. Live cells of Arthrospira sp. PCC 8005 were irradiated with 60Co gamma rays. This study is the first, showing that Arthrospira is highly tolerant to gamma rays, and can survive at least 6400 Gy (dose rate of 527 Gy h−1), which identified Arthrospira sp. PCC 8005 as a radiation resistant bacterium. Biochemical, including proteomic and tra...

  2. Identification and nitrogen regulation of the cyanase gene from the cyanobacteria Synechocystis sp. strain PCC 6803 and Synechococcus sp. strain PCC 7942.

    Science.gov (United States)

    Harano, Y; Suzuki, I; Maeda, S; Kaneko, T; Tabata, S; Omata, T

    1997-09-01

    An open reading frame (slr0899) on the genome of Synechocystis sp. strain PCC 6803 encodes a polypeptide of 149 amino acid residues, the sequence of which is 40% identical to that of cyanase from Escherichia coli. Introduction into a cyanase-deficient E. coli strain of a plasmid-borne slr0899 resulted in expression of low but significant activity of cyanase. Targeted interruption of a homolog of slr0899 from Synechococcus sp. strain PCC 7942, encoding a protein 77% identical to that encoded by slr0899, resulted in loss of cellular cyanase activity. These results indicated that slr0899 and its homolog in the strain PCC 7942 represent the cyanobacterial cyanase gene (designated cynS). While cynS of strain PCC 6803 is tightly clustered with the four putative molybdenum cofactor biosynthesis genes located downstream, cynS of strain PCC 7942 was found to be tightly clustered with the two genes located upstream, which encode proteins similar to the subunits of the cyanobacterial nitrate-nitrite transporter. In both strains, cynS was transcribed as a part of a large transcription unit and the transcription was negatively regulated by ammonium. Cyanase activity was low in ammonium-grown cells and was induced 7- to 13-fold by inhibition of ammonium fixation or by transfer of the cells to ammonium-free media. These findings indicated that cyanase is an ammonium-repressible enzyme in cyanobacteria, the expression of which is regulated at the level of transcription. Similar to other ammonium-repressible genes in cyanobacteria, expression of cynS required NtcA, a global nitrogen regulator of cyanobacteria.

  3. The Sakaguchi reaction product quenches phycobilisome fluorescence, allowing determination of the arginine concentration in cells of Anabaena strain PCC 7120.

    Science.gov (United States)

    Ke, Shan; Haselkorn, Robert

    2013-01-01

    The filamentous cyanobacterium Anabaena fixes nitrogen in specialized cells called heterocysts. The immediate product of fixation, ammonia, is known to be assimilated by addition to glutamate to make glutamine. How fixed nitrogen is transported along the filament to the 10 to 20 vegetative cells that separate heterocysts is unknown. N-fixing heterocysts accumulate an insoluble polymer containing aspartate and arginine at the cell poles. Lockau's group has proposed that the polymer is degraded at the poles to provide a mobile carrier, arginine, to the vegetative cells (R. Richter, M. Hejazi, R. Kraft, K. Ziegler, and W. Lockau, Eur. J. Biochem. 263:163-169, 1999). We wished to use the Sakaguchi reaction for arginine to determine the relative cellular concentration of arginine along the filament. At present, the methods for measuring absorption of the Sakaguchi reaction product at 520 nm are insufficiently sensitive for that purpose. However, that product quenches the fluorescence of phycobiliproteins, which we have adapted to a determination of arginine. Our results are consistent with the proposal that arginine is a principal nitrogen carrier from heterocysts to vegetative cells in Anabaena.

  4. Hydrogen production by Anabaena sp. CH1 with 2-stage process

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, C.L.; Lee, C.M. [National Chung Hsing Univ., Taiwan (China). Dept. of Environmental Engineering; Chen, P.C. [Hungkuang Univ., Taiwan (China). Dept. of Biomedical Nutrition

    2009-07-01

    While hydrogen can be produced by cyanobacteria under anoxic conditions, chlorophylls can break down and provide the nitrogen needed for cell material synthesis. The breakdown of chlorophylls is unfavorable for the long-term production of hydrogen. This study provided details of a 2-stage operation designed to prevent chlorophyll breakdown. Anabaena sp. CH1 was used in both the hydrogen production and recovery stages. Nitrogenase activity, chlorophyll concentrations, and hydrogen production rates decreased to 54 per cent after argon gases were used for a 3-day period. Growth conditions than shifted to normal conditions after 3 to 5 days. Cells recovered their nitrogenase activities, biomass, and chlorophyll concentrations within 4 days. The recovery stage then shifted to the hydrogen production stage, where hydrogen production rates were as high as previous observed rates. It was concluded that the effects of nitrogen deprivation on photosynthetic mechanisms are reversible.

  5. Heterologous expression of Anabaena PCC 7120 all3940 (a Dps family gene) protects Escherichia coli from nutrient limitation and abiotic stresses

    Energy Technology Data Exchange (ETDEWEB)

    Narayan, Om Prakash; Kumari, Nidhi [Molecular Biology Section, Laboratory of Algal Biology, Center of Advanced Study in Botany, Banaras Hindu University, Varanasi-22 1005 (India); Rai, Lal Chand, E-mail: lcraibhu@gmail.com [Molecular Biology Section, Laboratory of Algal Biology, Center of Advanced Study in Botany, Banaras Hindu University, Varanasi-22 1005 (India)

    2010-03-26

    This study presents first hand data on the cloning and heterologous expression of Anabaena PCC 7120 all3940 (a dps family gene) in combating nutrients limitation and multiple abiotic stresses. The Escherichia coli transformed with pGEX-5X-2-all3940 construct when subjected to iron, carbon, nitrogen, phosphorus limitation and carbofuron, copper, UV-B, heat, salt and cadmium stress registered significant increase in growth over the cells transformed with empty vector under iron (0%), carbon (0.05%), nitrogen (3.7 mM) and phosphorus (2 mM) limitation and carbofuron (0.025 mg ml{sup -1}), CuCl{sub 2} (1 mM), UV-B (10 min), heat (47 {sup o}C), NaCl (6% w/v) and CdCl{sub 2} (4 mM) stress. Enhanced expression of all3940 gene measured by semi-quantitative RT-PCR at different time points under above mentioned treatments clearly demonstrates its role in tolerance against aforesaid abiotic stresses. This study opens the gate for developing transgenic cyanobacteria capable of growing successfully under above mentioned stresses.

  6. UV-B stress induced metabolic rearrangements explored with comparative proteomics in three Anabaena species.

    Science.gov (United States)

    Shrivastava, Alok Kumar; Chatterjee, Antra; Yadav, Shivam; Singh, Prashant Kumar; Singh, Shilpi; Rai, L C

    2015-09-01

    Comparative proteomics together with physiological variables revealed different responses among three species of diazotrophic cyanobacterium Anabaena exposed to UV-B stress at the same time points. Perceptible decline in PSII activity, ATP pool, nitrogenase activity and respiration rate was observed for all the three species; this being maximum in Anabaena doliolum, followed by Anabaena sp. PCC 7120 and minimum in Anabaena L31. Statistical analysis of the protein abundance divided majority of them as early accumulated in A. L31, late accumulated in A. sp. PCC 7120 and downregulated in A. doliolum. Tolerance of A. L31 may be ascribed to post-translational modification reflected through the highest number of protein isoforms in its proteome followed by A. PCC 7120 and A. doliolum. Furthermore, increase in abundance of cyanophycinase, glutamine synthetase and succinate semialdehyde dehydrogenase in A. L31 suggests operation of an alternate pathway for assimilation of nitrogen and carbon under UV-B stress. An early accumulation of four proteins viz., glutamate ammonia ligase (Alr2328), transketolase (Alr3344), inorganic pyrophosphatase (All3570), and trigger protein (Alr3681) involved respectively in amino acid metabolism, energy metabolism, biosynthesis of cofactor and trigger protein and chaperone like activity across three species, suggests them to be marker of UV-B stress in Anabaena spp. This article is part of a Special Issue entitled: Proteomics in India.

  7. Relationship between color and pigment production in two stone biofilm-forming cyanobacteria (Nostoc sp. PCC 9104 and Nostoc sp. PCC 9025).

    Science.gov (United States)

    Sanmartín, P; Aira, N; Devesa-Rey, R; Silva, B; Prieto, B

    2010-07-01

    Previous studies have provided evidence that color measurements enable on site quantification of superficial biofilms, thereby avoiding the need for sampling. In the present study, the efficiency of color measurements to evaluate to what extent pigment production is affected by environmental parameters such as light intensity, combined nitrogen and nutrient availability, was tested with two cyanobacteria, Nostoc sp. strains PCC 9104 and PCC 9025, which form biofilms on stone. Both strains were acclimated, in aerated batch cultures for 2 weeks, to three different culture media: BG-11, BG-11(0), and BG-11(0)/10 at either high or low light intensity. The content of chlorophyll a, carotenoids, and phycocyanins was measured throughout the experiment, together with variations in the color of the cyanobacteria, which were represented in the CIELAB color space. The results confirmed that the CIELAB color parameters are correlated with pigment content in such a way that variations in the latter are reflected as variations in color.

  8. Study on Molecular Cloning and Enzyme Kinetics of Anabaena α-Phycocyanin Lyase%藻蓝蛋白α亚基裂合酶的分子克隆和酶动力学研究

    Institute of Scientific and Technical Information of China (English)

    苏平; 周明

    2012-01-01

    To comparatively study the differences on structures and functions of phycocyanin lyase CpcE/F from different cyanobacteria, CpcE/F from Anabaena sp. PCC 7120 were cloned and expressed greatly. The reconstitution of PCB and CpcA from Mastigocladus laminosus PCC 7603 in vitro using the overexpressed lyase Anabaena sp. PCC 7120 CpcE/F showed that CpcE/F from Anabaena sp. PCC 7120 is the specific enzyme for biosynthesis of α-PC, furthermore, the enzyme kinetics of PcE/F lyase were studied preliminarily.%为了比较研究不同藻种中藻蓝蛋白裂合酶CpcE/F的结构与功能的差异,对Anabaena sp.PCC 7120中的CpcE/F进行克隆,并进行大量表达,将表达的裂合酶CpcE/F用于藻蓝胆素(PCB)与Mastigocladus laminosus PCC 7603藻蓝蛋白α-亚基(α-PC)脱辅基蛋白(CpcA)的体外重组,得到天然活性的α-PC,从而表明CpcE/F所编码的蛋白质是α-PC生物合成的裂合酶,并对CpcE/F的酶动力学进行了初步研究.

  9. Establishment of quantitative PCR methods for the quantification of geosmin-producing potential and Anabaena sp. in freshwater systems.

    Science.gov (United States)

    Su, Ming; Gaget, Virginie; Giglio, Steven; Burch, Michael; An, Wei; Yang, Min

    2013-06-15

    Geosmin has often been associated with off-flavor problems in drinking water with Anabaena sp. as the major producer. Rapid on-site detection of geosmin-producers as well as geosmin is important for a timely management response to potential off-flavor events. In this study, quantitative polymerase chain reaction (qPCR) methods were developed to detect the levels of Anabaena sp. and geosmin, respectively, by designing two PCR primer sets to quantify the rpoC1 gene (ARG) and geosmin synthase one (GSG) in Anabaena sp. in freshwater systems. The ARG density determined by qPCR assay is highly related to microscopic cell count (r(2) = 0.726, p geosmin concentrations measured by gas chromatography-mass spectrometry (GC-MS) and GSG copies was also established (r(2) = 0.742, p < 0.001) with similar LOD and LOQ values. Using the two qPCR protocols, we succeeded in measuring different levels of ARG and GSG copies in different freshwater systems with high incidence environmental substrata and diverse ecological conditions, showing that the methods developed could be applied for environmental monitoring. Moreover, comparing to the microscopic count and GC-MS analytical methods, the qPCR methods can reduce the time-to-results from several days to a few hours and require considerably less traditional algal identification and taxonomic expertise.

  10. The influence of humic acid on the toxicity of nano-ZnO and Zn2+ to the Anabaena sp.

    Science.gov (United States)

    Tang, Yulin; Li, Shuyan; Lu, Yao; Li, Qian; Yu, Shuili

    2015-07-01

    This study explored the effects of humic acid (HA) on the toxicity of ZnO nanoparticles (nano-ZnO) and Zn(2+) to Anabaena sp. Typical chlorophyll fluorescence parameters, including effective quantum yield, photosynthetic efficiency and maximal electron transport rate, were measured by a pulse-amplitude modulated fluorometer. Results showed that nano-ZnO and Zn(2+) could inhibit Anabaena sp. growth with the EC50 (concentration for 50% of maximal effect) of 0.74 ± 0.01 and 0.3 ± 0.01 mg/L, respectively. In the presence of 3.0 mg/L of HA, EC50 of nano-ZnO increased to 1.15 ± 0.04 mg/L and EC50 of Zn(2+) was still 0.3 ± 0.01 mg/L. Scanning electron microscopy observation revealed that HA prevented the adhesion of nano-ZnO on the algae cells due to the increased electrostatic repulsion. The generation of intracellular reactive oxygen species and cellular lipid peroxidation were significantly limited by HA. Nano-ZnO had more damage to the cell membrane than Zn(2+) did, which could be proven by the malondialdehyde content in Anabaena sp. cells. © 2014 Wiley Periodicals, Inc. Environ Toxicol 30: 895-903, 2015.

  11. Fatty alcohols can complement functions of heterocyst specific glycolipids in Anabaena sp. PCC 7120.

    Science.gov (United States)

    Halimatul, Heli Siti Munawaroh; Ehira, Shigeki; Awai, Koichiro

    2014-07-18

    Heterocyst glycolipid synthase (HglT) catalyzes the final step of heterocyst glycolipid (Hgl) biosynthesis, in which a glucose is transferred to the aglycone (fatty alcohol). Here we describe the isolation of hglT null mutants. These mutants lacked Hgls under nitrogen-starved conditions and instead accumulated fatty alcohols. Differentiated heterocyst cells in the mutants were morphologically indistinguishable from those of the wild-type cells. Interestingly, the mutants grew under nitrogen starvation but fixed nitrogen with lower nitrogenase activity than did the wild-type. The mutants had a pale green phenotype with a decreased chlorophyll content, especially under nitrogen-starved conditions. These results suggest that the glucose moiety of the Hgls may be necessary for optimal protection against oxygen influx but is not essential and that aglycones can function as barriers against oxygen influx in the heterocyst cells.

  12. Detection of reactive oxygen species (ROS) by the oxidant-sensing probe 2',7'-dichlorodihydrofluorescein diacetate in the cyanobacterium Anabaena variabilis PCC 7937

    Energy Technology Data Exchange (ETDEWEB)

    Rastogi, Rajesh P. [Department of Biology, Friedrich-Alexander University Erlangen-Nuremberg, Staudtstrasse 5, D-91058 Erlangen (Germany); Laboratory of Photobiology and Molecular Microbiology, Centre of Advanced Study in Botany, Banaras Hindu University, Varanasi 221005 (India); Singh, Shailendra P.; Haeder, Donat-P. [Department of Biology, Friedrich-Alexander University Erlangen-Nuremberg, Staudtstrasse 5, D-91058 Erlangen (Germany); Sinha, Rajeshwar P., E-mail: r.p.sinha@gmx.net [Laboratory of Photobiology and Molecular Microbiology, Centre of Advanced Study in Botany, Banaras Hindu University, Varanasi 221005 (India)

    2010-07-02

    The generation of reactive oxygen species (ROS) under simulated solar radiation (UV-B: 0.30 Wm{sup -2}, UV-A: 25.70 Wm{sup -2} and PAR: 118.06 Wm{sup -2}) was studied in the cyanobacterium Anabaena variabilis PCC 7937 using the oxidant-sensing fluorescent probe 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA). DCFH-DA is a nonpolar dye, converted into the polar derivative DCFH by cellular esterases that are nonfluorescent but switched to highly fluorescent DCF when oxidized by intracellular ROS and other peroxides. The images obtained from the fluorescence microscope after 12 h of irradiation showed green fluorescence from cells covered with 295, 320 or 395 nm cut-off filters, indicating the generation of ROS in all treatments. However, the green/red fluorescence ratio obtained from fluorescence microscopic analysis showed the highest generation of ROS after UV-B radiation in comparison to PAR or UV-A radiation. Production of ROS was also measured by a spectrofluorophotometer and results obtained supported the results of fluorescence microscopy. Low levels of ROS were detected at the start (0 h) of the experiment showing that they are generated even during normal metabolism. This study also showed that UV-B radiation causes the fragmentation of the cyanobacterial filaments which could be due to the observed oxidative stress. This is the first report for the detection of intracellular ROS in a cyanobacterium by fluorescence microscopy using DCFH-DA and thereby suggesting the applicability of this method in the study of in vivo generation of ROS.

  13. Bifunctional enzyme FBPase/SBPase is essential for photoautotrophic growth in cyanobacterium Synechocystis sp. PCC 6803

    Institute of Scientific and Technical Information of China (English)

    Chunlan Yan; Xudong Xu

    2008-01-01

    From a random insertion mutant library of Synechocystis sp. PCC 6803, a mutant defective in photoautotrophic growth was obtained. The interrupted gene was identified to be sir2094 (fbpl), which encodes the fructose-l,6-biphosphatase (FBPase)/sedoheptu-lose-1,7-biphosphatase (SBPase) bifunctional enzyme (F-I). Two other independently constructed slr2094 mutants showed an identical phenotype. The FBPase activity was found to be virtually lacking in an sir2094 mutant, which was sensitive to light under mixotrophic growth conditions. These results indicate that sir2094 is the only active FBPase-encoding gene in this cyanobacterium. Inactivation of photosystem 11 by interrupting psbB in sir2094 mutant alleviated the sensitiveness to light. This report provides the direct genetic evi-dence for the essential role of F-I in the photosynthesis of Synechocystis sp. PCC 6803.

  14. Deep sequencing-based identification of small regulatory RNAs in Synechocystis sp. PCC 6803.

    Directory of Open Access Journals (Sweden)

    Wen Xu

    Full Text Available Synechocystis sp. PCC 6803 is a genetically tractable model organism for photosynthesis research. The genome of Synechocystis sp. PCC 6803 consists of a circular chromosome and seven plasmids. The importance of small regulatory RNAs (sRNAs as mediators of a number of cellular processes in bacteria has begun to be recognized. However, little is known regarding sRNAs in Synechocystis sp. PCC 6803. To provide a comprehensive overview of sRNAs in this model organism, the sRNAs of Synechocystis sp. PCC 6803 were analyzed using deep sequencing, and 7,951,189 reads were obtained. High quality mapping reads (6,127,890 were mapped onto the genome and assembled into 16,192 transcribed regions (clusters based on read overlap. A total number of 5211 putative sRNAs were revealed from the genome and the 4 megaplasmids, and 27 of these molecules, including four from plasmids, were confirmed by RT-PCR. In addition, possible target genes regulated by all of the putative sRNAs identified in this study were predicted by IntaRNA and analyzed for functional categorization and biological pathways, which provided evidence that sRNAs are indeed involved in many different metabolic pathways, including basic metabolic pathways, such as glycolysis/gluconeogenesis, the citrate cycle, fatty acid metabolism and adaptations to environmentally stress-induced changes. The information from this study provides a valuable reservoir for understanding the sRNA-mediated regulation of the complex physiology and metabolic processes of cyanobacteria.

  15. Near-UV cyanobacteriochrome signaling system elicits negative phototaxis in the cyanobacterium Synechocystis sp. PCC 6803

    OpenAIRE

    Song, Ji-Young; Cho, Hye Sun; Cho, Jung-Il; Jeon, Jong-Seong; Lagarias, J. Clark; Park, Youn-Il

    2011-01-01

    Positive phototaxis systems have been well studied in bacteria; however, the photoreceptor(s) and their downstream signaling components that are responsible for negative phototaxis are poorly understood. Negative phototaxis sensory systems are important for cyanobacteria, oxygenic photosynthetic organisms that must contend with reactive oxygen species generated by an abundance of pigment photosensitizers. The unicellular cyanobacterium Synechocystis sp. PCC6803 exhibits type IV pilus-dependen...

  16. Effect of growth conditions on the hydrogen production with cyanobacterium Anabaena sp. strain CH3

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Pei-Chung [Institute of Clinical Nutrition, Hungkuang University, 34, Chung-Chie Road, Sha Lu, Taichung 433 (China); Fan, Shin-Huei; Chiang, Char-Lin; Lee, Chi-Mei [Department of Environmental Engineering, National Chung Hsing University, 250, Kuo-Kuang Road, Taichung 402 (China)

    2008-03-15

    Cyanobacteria could use sugars as carbon source and reductant to produce hydrogen by nitrogenase. However, oxygen is also produced during photosynthesis and it is an inhibitor of the enzyme nitrogenase. Filamentous cyanobacterium Anabaena sp. CH{sub 3} could use sugars as substrate to produce molecular hydrogen anaerobically. The production activity was dependent on growth phases. It was found that the cells at sub-stage of late-log phase had better ability to produce hydrogen than at log phase. In such case, oxygen content was too low to be detected to inhibit hydrogen production. Among different kinds of sugar, fructose and glucose had the best performance for producing hydrogen. Hydrogen could be accumulated to 0.6 mmol (in 40 ml head space) in 100 h from 1000 ppm fructose. Increasing light intensities from 65 to 130{mu}molm{sup -2}s{sup -1} would enhance hydrogen production to 0.8 mmol. Under illumination of 130{mu}molm{sup -2}s{sup -1} and 2000 ppm fructose, 1.7 mmol of hydrogen could be accumulated. When fructose content was higher than 2000 ppm, cells could not produce more hydrogen at all. (author)

  17. Anabaena sp. DyP-type peroxidase is a tetramer consisting of two asymmetric dimers.

    Science.gov (United States)

    Yoshida, Toru; Ogola, Henry Joseph Oduor; Amano, Yoshimi; Hisabori, Toru; Ashida, Hiroyuki; Sawa, Yoshihiro; Tsuge, Hideaki; Sugano, Yasushi

    2016-01-01

    DyP-type peroxidases are a newly discovered family of heme peroxidases distributed from prokaryotes to eukaryotes. Recently, using a structure-based sequence alignment, we proposed the new classes, P, I and V, as substitutes for classes A, B, C, and D [Arch Biochem Biophys 2015;574:49-55]. Although many class V enzymes from eukaryotes have been characterized, only two from prokaryotes have been reported. Here, we show the crystal structure of one of these two enzymes, Anabaena sp. DyP-type peroxidase (AnaPX). AnaPX is tetramer formed from Cys224-Cys224 disulfide-linked dimers. The tetramer of wild-type AnaPX was stable at all salt concentrations tested. In contrast, the C224A mutant showed salt concentration-dependent oligomeric states: in 600 mM NaCl, it maintained a tetrameric structure, whereas in the absence of salt, it dissociated into monomers, leading to a reduction in thermostability. Although the tetramer exhibits non-crystallographic, 2-fold symmetry in the asymmetric unit, two subunits forming the Cys224-Cys224 disulfide-linked dimer are related by 165° rotation. This asymmetry creates an opening to cavities facing the inside of the tetramer, providing a pathway for hydrogen peroxide access. Finally, a phylogenetic analysis using structure-based sequence alignments showed that class V enzymes from prokaryotes, including AnaPX, are phylogenetically closely related to class V enzymes from eukaryotes.

  18. Effects of recombinated Anabaena sp. lipoxygenase on the protein component and dough property of wheat flour.

    Science.gov (United States)

    Wang, Xiaoming; Lu, Fengxia; Zhang, Chong; Lu, Yingjian; Bie, Xiaomei; Xie, Yajuan; Lu, Zhaoxin

    2014-10-08

    The improvement effect of recombinated Anabaena sp. lipoxygenase (ana-rLOX) on the rheological property of dough was investigated with a farinograph and an extensograph. When 30 U/g ana-rLOX was added to wheat flour, the dough stability time extended from 7 to 9.5 min, the degree of softening increased about 31.1%, and the farinograph index also ascended. The dough with added ana-rLOX showed stronger resistance to extension throughout 135 min of resting time as compared to the dough without ana-rLOX. In addition, the protein component in the dough was varied with ana-rLOX. The glutenin in the dough was increased, whereas the gliadin, albumin, and globulin were decreased after the additino of ana-rLOX to the flours. Ana-rLOX could make globulin-3A, globulin 1a, and S48186 grain softness protein cross-link with gliadin and low-molecular-weight (LMW) glutenin, leading to the formation of the protein polymer. These results based on proteomic analysis might provide evidence that ana-rLOX could affect the gluten protein component and explain why it improved the farinograph and extensograph parameters of wheat flour.

  19. Assessment of the effect of azo dye RP2B on the growth of a nitrogen fixing cyanobacterium--Anabaena sp.

    Science.gov (United States)

    Hu, T L; Wu, S C

    2001-03-01

    Certain nitrogen fixing cyanobacteria are diazotrophic, which profoundly impacts the aquatic ecosystem chemically and biologically. Although certain types are banned due to their carcinogenicity, azo dyes are commonly used in the dyeing or textile industry. This work investigates the effect of azo dye on the growth of cyanobacteria. Anabaena sp. isolated from the Da Jia Brook is an odor producing, nitrogen fixing cyanobacterium. The growth rates of Anabaena sp. in the media with or without nitrogen source were 3.56 x 10(-2) mg/ml day and 2.44 x 10(-2) mg/ml day, respectively. Anabaena sp. could not use azo dye RP2B as the nitrogen source. Experimental results indicated that the growth of Anabaena sp. was inhibited in the medium containing RP2B. The degree of inhibition increased from 50% to 81% with an increasing concentration of RP2B (0-50 mg/l). The IC-50 (inhibitory concentration) of RP2B on the growth of Anabaena sp. was 5 mg/l (as based on dry weight) or 7 mg/l (as measured by chlorophyll a).

  20. In vitro antibacterial evaluation of Anabaena sp. against several clinically significant microflora and HPTLC analysis of its active crude extracts

    Directory of Open Access Journals (Sweden)

    Chauhan Abhishek

    2010-01-01

    Full Text Available The present study was conducted to evaluate the possible antibacterial activity of Anabaena extracts. Anabaena was isolated from a natural source and cultured in vitro. after suitable growth, cyanobacterial culture was harvested using different solvents. Extracts, thus prepared, were evaluated for their antibacterial potential by agar-well diffusion assay against bacterial species of clinical significance. MIC values were determined further to check the concentration ranges for significant inhibition. HPTLC analysis was done to separate the components of active crude extract in an attempt to identify the bio-active chemical entity. Methanol extract exhibited more potent activity than that of hexane and ethyl acetate extracts. No inhibitory effect was found against Pseudomonas aeruginosa, Salmonella typhi, and Klebsiella pneumoniae. Staphylococcus aureus required about 256 μg/ml of the crude methanol extract for effective inhibition. HPTLC evaluation at λ 254 nm was performed for the separation of a complex mixture of the methanol extract. The results provide evidence that Anabaena sp. extracts might indeed be potential sources of new antibacterial agents.

  1. Assessment of the CO2 fixation capacity of Anabaena sp. ATCC 33047 outdoor cultures in vertical flat-panel reactors.

    Science.gov (United States)

    Clares, Marta E; Moreno, José; Guerrero, Miguel G; García-González, Mercedes

    2014-10-10

    The extent of biological CO2 fixation was evaluated for outdoor cultures of the cyanobacterium Anabaena sp. ATCC 33047. Culture conditions were optimized indoors in bubble-column photochemostats operating in continuous mode, subjected to irradiance cycles mimicking the light regime outdoors. Highest values achieved for CO2 fixation rate and biomass productivity were 1 and 0.6 g L(-1) day(-1), respectively. The comparison among different reactors operating simultaneously - open pond, horizontal tubular reactor and vertical flat-panel - allowed to assess their relative efficiency for the outdoor development of Anabaena cultures. Despite the higher volumetric CO2 fixation capacity (and biomass productivity) exhibited by the tubular photobioreactor, yield of the flat-panel reactor was 50% higher than that of the tubular option on a per area basis, reaching values over 35 g CO2 fixed m(-2) d(-1). The flat-panel reactor actually represents a most suitable system for CO2 capture coupled to the generation of valuable biomass by Anabaena cultures.

  2. The biosynthetic pathway for myxol-2' fucoside (myxoxanthophyll) in the cyanobacterium Synechococcus sp. strain PCC 7002.

    Science.gov (United States)

    Graham, Joel E; Bryant, Donald A

    2009-05-01

    Synechococcus sp. strain PCC 7002 produces a variety of carotenoids, which comprise predominantly dicylic beta-carotene and two dicyclic xanthophylls, zeaxanthin and synechoxanthin. However, this cyanobacterium also produces a monocyclic myxoxanthophyll, which was identified as myxol-2' fucoside. Compared to the carotenoid glycosides produced by diverse microorganisms, cyanobacterial myxoxanthophyll and closely related compounds are unusual because they are glycosylated on the 2'-OH rather than on the 1'-OH position of the psi end of the molecule. In this study, the genes encoding two enzymes that modify the psi end of myxoxanthophyll in Synechococcus sp. strain PCC 7002 were identified. Mutational and biochemical studies showed that open reading frame SynPCC7002_A2032, renamed cruF, encodes a 1',2'-hydroxylase [corrected] and that open reading frame SynPCC7002_A2031, renamed cruG, encodes a 2'-O-glycosyltransferase. The enzymatic activity of CruF was verified by chemical characterization of the carotenoid products synthesized when cruF was expressed in a lycopene-producing strain of Escherichia coli. Database searches showed that homologs of cruF and cruG occur in the genomes of all sequenced cyanobacterial strains that are known to produce myxol or the acylic xanthophyll oscillaxanthin. The genomes of many other bacteria that produce hydroxylated carotenoids but do not contain crtC homologs also contain cruF orthologs. Based upon observable intermediates, a complete biosynthetic pathway for myxoxanthophyll is proposed. This study expands the suite of enzymes available for metabolic engineering of carotenoid biosynthetic pathways for biotechnological applications.

  3. Transcriptomic and Proteomic Profiling of Anabaena sp. Strain 90 under Inorganic Phosphorus Stress.

    Science.gov (United States)

    Teikari, Jonna; Österholm, Julia; Kopf, Matthias; Battchikova, Natalia; Wahlsten, Matti; Aro, Eva-Mari; Hess, Wolfgang R; Sivonen, Kaarina

    2015-08-01

    Inorganic phosphorus (Pi) is one of the main growth-limiting factors of diazotrophic cyanobacteria. Due to human activity, the availability of Pi has increased in water bodies, resulting in eutrophication and the formation of massive cyanobacterial blooms. In this study, we examined the molecular responses of the cyanobacterium Anabaena sp. strain 90 to phosphorus deprivation, aiming at the identification of candidate genes to monitor the Pi status in cyanobacteria. Furthermore, this study increased the basic understanding of how phosphorus affects diazotrophic and bloom-forming cyanobacteria as a major growth-limiting factor. Based on RNA sequencing data, we identified 246 differentially expressed genes after phosphorus starvation and 823 differentially expressed genes after prolonged Pi limitation, most of them related to central metabolism and cellular growth. The transcripts of the genes related to phosphorus transport and assimilation (pho regulon) were most upregulated during phosphorus depletion. One of the most increased transcripts encodes a giant protein of 1,869 amino acid residues, which contains, among others, a phytase-like domain. Our findings predict its crucial role in phosphorus starvation, but future studies are still needed. Using two-dimensional difference in gel electrophoresis (2D-DIGE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS), we found 43 proteins that were differentially expressed after prolonged phosphorus stress. However, correlation analysis unraveled an association only to some extent between the transcriptomic and proteomic abundances. Based on the present results, we suggest that the method used for monitoring the Pi status in cyanobacterial bloom should contain wider combinations of pho regulon genes (e.g., PstABCS transport systems) in addition to the commonly used alkaline phosphatase gene alone.

  4. Molecular exploration of the highly radiation resistant cyanobacterium Arthrospira sp. PCC 8005

    Science.gov (United States)

    Badri, Hanène; Leys, Natalie; Wattiez, Ruddy

    Arthrospira (Spirulina) is a photosynthetic cyanobacterium able to use sunlight to release oxygen from water and remove carbon dioxide and nitrate from water. In addition, it is suited for human consumption (edible). For these traits, the cyanobacterium Arthrospira sp. PCC 8005 was selected by the European Space Agency (ESA) as part of the life support system MELiSSA for recycling oxygen, water, and food during future long-haul space missions. However, during such extended missions, Arthrospira sp. PCC 8005 will be exposed to continuous artificial illumination and harmful cosmic radiation. The aim of this study was to investigate how Arthrospira will react and behave when exposed to such stress environment. The cyanobacterium Arthrospira sp. PCC 8005 was exposed to high gamma rays doses in order to unravel in details the response of this bacterium following such stress. Test results showed that after acute exposure to high doses of 60Co gamma radiation upto 3200 Gy, Arthrospira filaments were still able to restart photosynthesis and proliferate normally. Doses above 3200 Gy, did have a detrimental effect on the cells, and delayed post-irradiation proliferation. The photosystem activity, measured as the PSII quantum yield immediately after irradiation, decreased significantly at radiation doses above 3200 Gy. Likewise through pigment content analysis a significant decrease in phycocyanin was observed following exposure to 3200 Gy. The high tolerance of this bacterium to 60Co gamma rays (i.e. ca. 1000x more resistant than human cells for example) raised our interest to investigate in details the cellular and molecular mechanisms behind this amazing resistance. Optimised DNA, RNA and protein extraction methods and a new microarray chip specific for Arthrospira sp. PCC 8005 were developed to identify the global cellular and molecular response following exposure to 3200 Gy and 5000 Gy A total of 15,29 % and 30,18 % genes were found differentially expressed in RNA

  5. Effects of fatty acid activation on photosynthetic production of fatty acid-based biofuels in Synechocystis sp. PCC6803

    Directory of Open Access Journals (Sweden)

    Gao Qianqian

    2012-03-01

    Full Text Available Abstract Background Direct conversion of solar energy and carbon dioxide to drop in fuel molecules in a single biological system can be achieved from fatty acid-based biofuels such as fatty alcohols and alkanes. These molecules have similar properties to fossil fuels but can be produced by photosynthetic cyanobacteria. Results Synechocystis sp. PCC6803 mutant strains containing either overexpression or deletion of the slr1609 gene, which encodes an acyl-ACP synthetase (AAS, have been constructed. The complete segregation and deletion in all mutant strains was confirmed by PCR analysis. Blocking fatty acid activation by deleting slr1609 gene in wild-type Synechocystis sp. PCC6803 led to a doubling of the amount of free fatty acids and a decrease of alkane production by up to 90 percent. Overexpression of slr1609 gene in the wild-type Synechocystis sp. PCC6803 had no effect on the production of either free fatty acids or alkanes. Overexpression or deletion of slr1609 gene in the Synechocystis sp. PCC6803 mutant strain with the capability of making fatty alcohols by genetically introducing fatty acyl-CoA reductase respectively enhanced or reduced fatty alcohol production by 60 percent. Conclusions Fatty acid activation functionalized by the slr1609 gene is metabolically crucial for biosynthesis of fatty acid derivatives in Synechocystis sp. PCC6803. It is necessary but not sufficient for efficient production of alkanes. Fatty alcohol production can be significantly improved by the overexpression of slr1609 gene.

  6. On-water remote monitoring robotic system for estimating the patch coverage of Anabaena sp. filaments in shallow water.

    Science.gov (United States)

    Romero-Vivas, E; Von Borstel, F D; Pérez-Estrada, C J; Torres-Ariño, D; Villa-Medina, J F; Gutiérrez, J

    2015-06-01

    An on-water remote monitoring robotic system was developed for indirectly estimating the relative density of marine cyanobacteria blooms at the subtidal sandy-rocky beach in Balandra Cove, Baja California Sur, Mexico. The system is based on an unmanned surface vehicle to gather underwater videos of the seafloor for avoiding physical damage on Anabaena sp. cyanobacteria colonies, which grow in tufts of filaments weakly attached to rocks, seagrass, and macroalgae. An on-axis image stabilization mechanism was developed to support a camcorder and minimize wave perturbation while recording underwater digital images of the seafloor. Color image processing algorithms were applied to estimate the patch coverage area and density, since Anabaena sp. filaments exhibit a characteristic green tone. Results of field tests showed the feasibility of the robotic system to estimate the relative density, distribution, and coverage area of cyanobacteria blooms, preventing the possible impact of direct observation. The robotic system could also be used in surveys of other benthos in the sublittoral zone.

  7. Phycobilisome Truncation Causes Widespread Proteome Changes in Synechocystis sp. PCC 6803

    Energy Technology Data Exchange (ETDEWEB)

    Liberton, Michelle L.; Chrisler, William B.; Nicora, Carrie D.; Moore, Ronald J.; Smith, Richard D.; Koppenaal, David W.; Pakrasi, Himadri B.; Jacobs, Jon M.

    2017-03-02

    Cyanobacteria, such as Synechocystis sp. PCC 6803, utilize large antenna systems to optimize light harvesting and energy transfer to reaction centers. Understanding the structure and function of these complexes, particularly when altered, will help direct bio-design efforts to optimize biofuel production. Three specific phycobilisome (PBS) complex truncation mutants were studied, ranging from progressive truncation of phycocyanin rods in the CB and CK strains, to full removal of all phycocyanin and allophycocyanin cores in the PAL mutant. We applied comprehensive proteomic analyses to investigate both direct and downstream molecular systems implications of each truncation. Results showed that PBS truncation in Synechocystis sp. PCC 6803 dramatically alters core cellular mechanisms beyond energy capture and electron transport, placing constraints upon cellular processes that dramatically altered phenotypes. This included primarily membrane associated functions and altered regulation of cellular resources (i.e., iron, nitrite/nitrate, bicarbonate). Additionally, each PBS truncation, though progressive in nature, exhibited unique phenotypes compare to WT, and hence we assert that in the current realm of extensive bioengineering and bio-design, there remains a continuing need to assess systems-wide protein based abundances to capture potential indirect phenotypic effects.

  8. Proteomic and cellular views of Arthrospira sp. PCC 8005 adaptation to nitrogen depletion.

    Science.gov (United States)

    Deschoenmaeker, Frédéric; Facchini, Raphaël; Leroy, Baptiste; Badri, Hanène; Zhang, C-C; Wattiez, Ruddy

    2014-06-01

    Cyanobacteria are photosynthetic prokaryotes that play a crucial role in the Earth's nitrogen and carbon cycles. Nitrogen availability is one of the most important factors in cyanobacterial growth. Interestingly, filamentous non-diazotrophic cyanobacteria, such as Arthrospira sp. PCC 8005, have developed survival strategies that enable them to adapt to nitrogen deprivation. Metabolic studies recently demonstrated a substantial synthesis and accumulation of glycogen derived from amino acids during nitrogen starvation. Nevertheless, the regulatory mechanism of this adaptation is poorly understood. To the best of our knowledge, this study is the first proteomic and cellular analysis of Arthrospira sp. PCC 8005 under nitrogen depletion. Label-free differential proteomic analysis indicated the global carbon and nitrogen reprogramming of the cells during nitrogen depletion as characterized by an upregulation of glycogen synthesis and the use of endogenous nitrogen sources. The degradation of proteins and cyanophycin provided endogenous nitrogen when exogenous nitrogen was limited. Moreover, formamides, cyanates and urea were also potential endogenous nitrogen sources. The transporters of some amino acids and alternative nitrogen sources such as ammonium permease 1 were induced under nitrogen depletion. Intriguingly, although Arthrospira is a non-diazotrophic cyanobacterium, we observed the upregulation of HetR and HglK proteins, which are involved in heterocyst differentiation. Moreover, after a long period without nitrate, only a few highly fluorescent cells in each trichome were observed, and they might be involved in the long-term survival mechanism of this non-diazotrophic cyanobacterium under nitrogen deprivation.

  9. Synechocystis sp. PCC 6803 CruA (sll0147) encodes lycopene cyclase and requires bound chlorophyll a for activity.

    Science.gov (United States)

    Xiong, Wei; Shen, Gaozhong; Bryant, Donald A

    2017-03-01

    The genome of the model cyanobacterium, Synechococcus sp. PCC 7002, encodes two paralogs of CruA-type lycopene cyclases, SynPCC7002_A2153 and SynPCC7002_A0043, which are denoted cruA and cruP, respectively. Unlike the wild-type strain, a cruA deletion mutant is light-sensitive, grows slowly, and accumulates lycopene, γ-carotene, and 1-OH-lycopene; however, this strain still produces β-carotene and other carotenoids derived from it. Expression of cruA from Synechocystis sp. PCC 6803 (cruA 6803) in Escherichia coli strains that synthesize either lycopene or γ-carotene did not lead to the synthesis of either γ-carotene or β-carotene, respectively. However, expression of this orthologous cruA 6803 gene (sll0147) in the Synechococcus sp. PCC 7002 cruA deletion mutant produced strains with phenotypic properties identical to the wild type. CruA6803 was purified from Synechococcus sp. PCC 7002 by affinity chromatography, and the purified protein was pale yellow-green due to the presence of bound chlorophyll (Chl) a and β-carotene. Native polyacrylamide gel electrophoresis of the partly purified protein in the presence of lithium dodecylsulfate at 4 °C confirmed that the protein was yellow-green in color. When purified CruA6803 was assayed in vitro with either lycopene or γ-carotene as substrate, β-carotene was synthesized. These data establish that CruA6803 is a lycopene cyclase and that it requires a bound Chl a molecule for activity. Possible binding sites for Chl a and the potential regulatory role of the Chl a in coordination of Chl and carotenoid biosynthesis are discussed.

  10. Transcription of the extended hyp-operon in Nostoc sp. strain PCC 7120

    Directory of Open Access Journals (Sweden)

    Lindblad Peter

    2008-04-01

    Full Text Available Abstract Background The maturation of hydrogenases into active enzymes is a complex process and e.g. a correctly assembled active site requires the involvement of at least seven proteins, encoded by hypABCDEF and a hydrogenase specific protease, encoded either by hupW or hoxW. The N2-fixing cyanobacterium Nostoc sp. strain PCC 7120 may contain both an uptake and a bidirectional hydrogenase. The present study addresses the presence and expression of hyp-genes in Nostoc sp. strain PCC 7120. Results RT-PCRs demonstrated that the six hyp-genes together with one ORF may be transcribed as a single operon. Transcriptional start points (TSPs were identified 280 bp upstream from hypF and 445 bp upstream of hypC, respectively, demonstrating the existence of several transcripts. In addition, five upstream ORFs located in between hupSL, encoding the small and large subunits of the uptake hydrogenase, and the hyp-operon, and two downstream ORFs from the hyp-genes were shown to be part of the same transcript unit. A third TSP was identified 45 bp upstream of asr0689, the first of five ORFs in this operon. The ORFs are annotated as encoding unknown proteins, with the exception of alr0692 which is identified as a NifU-like protein. Orthologues of the four ORFs asr0689-alr0692, with a highly conserved genomic arrangement positioned between hupSL, and the hyp genes are found in several other N2-fixing cyanobacteria, but are absent in non N2-fixing cyanobacteria with only the bidirectional hydrogenase. Short conserved sequences were found in six intergenic regions of the extended hyp-operon, appearing between 11 and 79 times in the genome. Conclusion This study demonstrated that five ORFs upstream of the hyp-gene cluster are co-transcribed with the hyp-genes, and identified three TSPs in the extended hyp-gene cluster in Nostoc sp. strain PCC 7120. This may indicate a function related to the assembly of a functional uptake hydrogenase, hypothetically in the

  11. Construction of new synthetic biology tools for the control of gene expression in the cyanobacterium Synechococcus sp. strain PCC 7002.

    Science.gov (United States)

    Zess, Erin K; Begemann, Matthew B; Pfleger, Brian F

    2016-02-01

    Predictive control of gene expression is an essential tool for developing synthetic biological systems. The current toolbox for controlling gene expression in cyanobacteria is a barrier to more in-depth genetic analysis and manipulation. Towards relieving this bottleneck, this work describes the use of synthetic biology to construct an anhydrotetracycline-based induction system and adapt a trans-acting small RNA (sRNA) system for use in the cyanobacterium Synechococcus sp. strain PCC 7002. An anhydrotetracycline-inducible promoter was developed to maximize intrinsic strength and dynamic range. The resulting construct, PEZtet , exhibited tight repression and a maximum 32-fold induction upon addition of anhydrotetracycline. Additionally, a sRNA system based on the Escherichia coli IS10 RNA-IN/OUT regulator was adapted for use in Synechococcus sp. strain PCC 7002. This system exhibited 70% attenuation of target gene expression, providing a demonstration of the use of sRNAs for differential gene expression in cyanobacteria. These systems were combined to produce an inducible sRNA system, which demonstrated 59% attenuation of target gene expression. Lastly, the role of Hfq, a critical component of sRNA systems in E. coli, was investigated. Genetic studies showed that the Hfq homolog in Synechococcus sp. strain PCC 7002 did not impact repression by the engineered sRNA system. In summary, this work describes new synthetic biology tools that can be applied to physiological studies, metabolic engineering, or sRNA platforms in Synechococcus sp. strain PCC 7002.

  12. An integrative approach to energy, carbon, and redox metabolism in the cyanobacterium Synechocystis sp. PCC 6803

    Energy Technology Data Exchange (ETDEWEB)

    Overbeek, Ross; Fonstein, Veronika; Osterman, Andrei; Gerdes, Svetlana; Vassieva, Olga; Zagnitko, Olga; Rodionov, Dmitry

    2005-02-15

    The team of the Fellowship for Interpretation of Genomes (FIG) under the leadership of Ross Overbeek, began working on this Project in November 2003. During the previous year, the Project was performed at Integrated Genomics Inc. A transition from the industrial environment to the public domain prompted us to adjust some aspects of the Project. Notwithstanding the challenges, we believe that these adjustments had a strong positive impact on our deliverables. Most importantly, the work of the research team led by R. Overbeek resulted in the deployment of a new open source genomic platform, the SEED (Specific Aim 1). This platform provided a foundation for the development of CyanoSEED a specialized portal to comparative analysis and metabolic reconstruction of all available cyanobacterial genomes (Specific Aim 3). The SEED represents a new generation of software for genome analysis. Briefly, it is a portable and extendable system, containing one of the largest and permanently growing collections of complete and partial genomes. The complete system with annotations and tools is freely available via browsing or via installation on a user's Mac or Linux computer. One of the important unique features of the SEED is the support of metabolic reconstruction and comparative genome analysis via encoding and projection of functional subsystems. During the project period, the FIG research team has validated the new software by developing a significant number of core subsystems, covering many aspects of central metabolism (Specific Aim 2), as well as metabolic areas specific for cyanobacteria and other photoautotrophic organisms (Specific Aim 3). In addition to providing a proof of technology and a starting point for further community-based efforts, these subsystems represent a valuable asset. An extensive coverage of central metabolism provides the bulk of information required for metabolic modeling in Synechocystis sp.PCC 6803. Detailed analysis of several subsystems

  13. Transient Effects of Salt Shock on the Photosynthetic Machinery in Synechocystis sp. PCC 6803

    Institute of Scientific and Technical Information of China (English)

    毛海滨; 阮翔; 李国富; 公衍道; 张秀芳; 赵南明

    2002-01-01

    The transient effects of NaCl on chlorophyll (Chl) fluorescence in Synechocystis sp. PCC 6803 cells were examined. In dark-adapted cells, salt shock induced a transition from state 2 to state 1, and the artificial quinones, phenyl-1,4-benzoquinone (PBQ) and 2,5-dibromo-3-methyl-6-isopropyl-1,4-benzoquinone (DBMIB), quenched the Chl fluorescence markedly after addition of 0.8 mol/L NaCl. In light-adapted cells, the addition of NaCl caused a significant increase in the stationary fluorescence yield, which resulted in a decrease in the quantum yield of photosystem II (PSII). The results indicate that salt shock can induce a change in the affinity between the photosystems and the phycobilisomes (PBS) and can perturb the orientation of the Chl molecules in PSII.

  14. An integrative approach to energy, carbon, and redox metabolism in the cyanobacterium Synechocystis sp. PCC 6803

    Energy Technology Data Exchange (ETDEWEB)

    Overbeek, Ross; Fonstein, Veronika; Osterman, Andrei; Gerdes, Svetlana; Vassieva, Olga; Zagnitko, Olga; Rodionov, Dmitry

    2005-02-15

    The team of the Fellowship for Interpretation of Genomes (FIG) under the leadership of Ross Overbeek, began working on this Project in November 2003. During the previous year, the Project was performed at Integrated Genomics Inc. A transition from the industrial environment to the public domain prompted us to adjust some aspects of the Project. Notwithstanding the challenges, we believe that these adjustments had a strong positive impact on our deliverables. Most importantly, the work of the research team led by R. Overbeek resulted in the deployment of a new open source genomic platform, the SEED (Specific Aim 1). This platform provided a foundation for the development of CyanoSEED a specialized portal to comparative analysis and metabolic reconstruction of all available cyanobacterial genomes (Specific Aim 3). The SEED represents a new generation of software for genome analysis. Briefly, it is a portable and extendable system, containing one of the largest and permanently growing collections of complete and partial genomes. The complete system with annotations and tools is freely available via browsing or via installation on a user's Mac or Linux computer. One of the important unique features of the SEED is the support of metabolic reconstruction and comparative genome analysis via encoding and projection of functional subsystems. During the project period, the FIG research team has validated the new software by developing a significant number of core subsystems, covering many aspects of central metabolism (Specific Aim 2), as well as metabolic areas specific for cyanobacteria and other photoautotrophic organisms (Specific Aim 3). In addition to providing a proof of technology and a starting point for further community-based efforts, these subsystems represent a valuable asset. An extensive coverage of central metabolism provides the bulk of information required for metabolic modeling in Synechocystis sp.PCC 6803. Detailed analysis of several subsystems

  15. A bioelectrochemical approach to characterize extracellular electron transfer by Synechocystis sp. PCC6803.

    Directory of Open Access Journals (Sweden)

    Angelo Cereda

    Full Text Available Biophotovoltaic devices employ photosynthetic organisms at the anode of a microbial fuel cell to generate electrical power. Although a range of cyanobacteria and algae have been shown to generate photocurrent in devices of a multitude of architectures, mechanistic understanding of extracellular electron transfer by phototrophs remains minimal. Here we describe a mediatorless bioelectrochemical device to measure the electrogenic output of a planktonically grown cyanobacterium, Synechocystis sp. PCC6803. Light dependent production of current is measured, and its magnitude is shown to scale with microbial cell concentration and light intensity. Bioelectrochemical characterization of a Synechocystis mutant lacking Photosystem II demonstrates conclusively that production of the majority of photocurrent requires a functional water splitting aparatus and electrons are likely ultimately derived from water. This shows the potential of the device to rapidly and quantitatively characterize photocurrent production by genetically modified strains, an approach that can be used in future studies to delineate the mechanisms of cyanobacterial extracellular electron transport.

  16. BMAA Inhibits Nitrogen Fixation in the Cyanobacterium Nostoc sp. PCC 7120

    Directory of Open Access Journals (Sweden)

    Birgitta Bergman

    2013-08-01

    Full Text Available Cyanobacteria produce a range of secondary metabolites, one being the neurotoxic non-protein amino acid β-N-methylamino-L-alanine (BMAA, proposed to be a causative agent of human neurodegeneration. As for most cyanotoxins, the function of BMAA in cyanobacteria is unknown. Here, we examined the effects of BMAA on the physiology of the filamentous nitrogen-fixing cyanobacterium Nostoc sp. PCC 7120. Our data show that exogenously applied BMAA rapidly inhibits nitrogenase activity (acetylene reduction assay, even at micromolar concentrations, and that the inhibition was considerably more severe than that induced by combined nitrogen sources and most other amino acids. BMAA also caused growth arrest and massive cellular glycogen accumulation, as observed by electron microscopy. With nitrogen fixation being a process highly sensitive to oxygen species we propose that the BMAA effects found here may be related to the production of reactive oxygen species, as reported for other organisms.

  17. Synechococcus sp. strain PCC 7002 transcriptome: acclimation to temperature, salinity, oxidative stress and mixotrophic growth conditions

    Directory of Open Access Journals (Sweden)

    Marcus eLudwig

    2012-10-01

    Full Text Available Synechococcus sp. strain PCC 7002 is a unicellular, euryhaline cyanobacterium. It is a model organism for studies of cyanobacterial metabolism and has great potential for biotechnological applications. It exhibits an exceptional tolerance of high light irradiation and shows very rapid growth. The habitats from which this and closely related strains were isolated are subject to changes in several environmental factors, including light, nutrient supply, temperature, and salinity. In this study global transcriptome profiling via RNAseq has been used to perform a comparative and integrated study of global changes in cells grown at different temperatures, at different salinities and under mixotrophic conditions, when a metabolizable organic carbon source was present. Furthermore, the transcriptomes were investigated for cells that were subjected to a heat shock and that were exposed to oxidative stress. Lower growth temperatures caused relatively minor changes of the transcriptome; the most prominent changes affected fatty acid desaturases. A heat shock caused severe changes of the transcriptome pattern; transcripts for genes associated with major metabolic pathways declined and those for different chaperones increased dramatically. Oxidative stress, however, left the transcript pattern almost unaffected. When grown at high salinity, Synechococcus sp. PCC 7002 had increased expression of genes involved in compatible solute biosynthesis and showed increased mRNA levels for several genes involved in electron transport. Transcripts of two adjacent genes dramatically increased upon growth at high salinity; the respective proteins are putatively involved in coping with oxidative stress and in triggering ion channels. Only minor changes were observed when cells were grown at low salinity or when the growth medium was supplemented with glycerol. However, the transcriptome data suggest that cells must acclimate to excess reducing equivalents when a reduced C

  18. Network analysis of transcriptomics expands regulatory landscapes in Synechococcus sp. PCC 7002

    Energy Technology Data Exchange (ETDEWEB)

    McClure, Ryan S.; Overall, Christopher C.; McDermott, Jason E.; Hill, Eric A.; Markillie, Lye Meng; McCue, Lee Ann; Taylor, Ronald C.; Ludwig, Marcus; Bryant, Donald A.; Beliaev, Alexander S.

    2016-08-27

    Cyanobacterial regulation of gene expression must contend with a genome organization that lacks apparent functional context, as the majority of cellular processes and metabolic pathways are encoded by genes found at disparate locations across the genome. In addition, the fact that coordinated regulation of cyanobacterial cellular machinery takes place with significantly fewer transcription factors, compared to other Eubacteria, suggests the involvement of post-transcriptional mechanisms and regulatory adaptations which are not fully understood. Global transcript abundance from model cyanobacterium Synechococcus sp. PCC 7002 grown under 42 different conditions was analyzed using context-likelihood of relatedness. The resulting 903-gene network, which was organized into 11 modules, not only allowed classification of cyanobacterial responses to specific environmental variables but provided insight into the transcriptional network topology and led to the expansion of predicted regulons. When used in conjunction with genome sequence, the global transcript abundance allowed identification of putative post-transcriptional changes in expression as well as novel potential targets of both DNA binding proteins and asRNA regulators. The results offer a new perspective into the multi-level regulation that governs cellular adaptations of fast-growing physiologically robust cyanobacterium Synechococcus sp. PCC 7002 to changing environmental variables. It also extends a methodological knowledge-based framework for studying multi-scale regulatory mechanisms that operate in cyanobacteria. Finally, it provides valuable context for integrating systems-level data to enhance evidence-driven genomic annotation, especially in organisms where traditional context analyses cannot be implemented due to lack of operon-based functional organization.

  19. Arsenic Demethylation by a C·As Lyase in Cyanobacterium Nostoc sp. PCC 7120.

    Science.gov (United States)

    Yan, Yu; Ye, Jun; Xue, Xi-Mei; Zhu, Yong-Guan

    2015-12-15

    Arsenic, a ubiquitous toxic substance, exists mainly as inorganic forms in the environment. It is perceived that organoarsenicals can be demethylated and degraded into inorganic arsenic by microorganisms. Few studies have focused on the mechanism of arsenic demethylation in bacteria. Here, we investigated arsenic demethylation in a typical freshwater cyanobacterium Nostoc sp. PCC 7120. This bacterium was able to demethylate monomethylarsenite [MAs(III)] rapidly to arsenite [As(III)] and also had the ability to demethylate monomethylarsenate [MAs(V)] to As(III). The NsarsI encoding a C·As lyase responsible for MAs(III) demethylation was cloned from Nostoc sp. PCC 7120 and heterologously expressed in an As-hypersensitive strain Escherichia coli AW3110 (ΔarsRBC). Expression of NsarsI was shown to confer MAs(III) resistance through arsenic demethylation. The purified NsArsI was further identified and functionally characterized in vitro. NsArsI existed mainly as the trimeric state, and the kinetic data were well-fit to the Hill equation with K0.5 = 7.55 ± 0.33 μM for MAs(III), Vmax = 0.79 ± 0.02 μM min(-1), and h = 2.7. Both of the NsArsI truncated derivatives lacking the C-terminal 10 residues (ArsI10) or 23 residues (ArsI23) had a reduced ability of MAs(III) demethylation. These results provide new insights for understanding the important role of cyanobacteria in arsenic biogeochemical cycling in the environment.

  20. Analysis of carbohydrate storage granules in the diazotrophic cyanobacterium Cyanothece sp. PCC 7822

    Energy Technology Data Exchange (ETDEWEB)

    Welkie, David G. [Purdue Univ., West Lafayette, IN (United States); Sherman, Debra M. [Purdue Univ., West Lafayette, IN (United States); Chrisler, William B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Orr, Galya [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Sherman, Louis A. [Purdue Univ., West Lafayette, IN (United States)

    2013-10-19

    The unicellular diazotrophic cyanobacteria of the genus Cyanothece demonstrate oscillations in nitrogenase activity and H2 production when grown under 12h light-12h dark cycles. We established that Cyanothece sp. PCC 7822 allows for the construction of knock-out mutants and our objective was to improve the growth characteristics of this strain and to identify the nature of the intracellular storage granules. We report the physiological and morphological effects of reduction in nitrate and phosphate concentrations in BG-11 media on this strain. We developed a series of BG-11-derived growth media and monitored batch culture growth, nitrogenase activity and nitrogenase-mediated hydrogen production, culture synchronicity, and intracellular storage content. Reduction in NaNO3 and K2HPO4 concentrations from 17.6 and 0.23 mM to 4.41 and 0.06 mM, respectively, improved growth characteristics such as cell size and uniformity, and enhanced the rate of cell division. Cells grown in this low NP BG-11 were less complex, a parameter that related to the composition of the intracellular storage granules. Cells grown in low NP BG-11 had less polyphosphate, fewer polyhydroxybutyrate granules and many smaller granules became evident. Biochemical analysis and transmission electron microscopy using the histocytochemical PATO technique demonstrated that these small granules contained glycogen. The glycogen levels and the number of granules per cell correlated nicely with a 2.3 to 3.3-fold change from the minimum at L0 to the maximum at D0. The differences in granule morphology and enzymes between Cyanothece ATCC 51142 and Cyanothece PCC 7822 provide insights into the formation of large starch-like granules in some cyanobacteria.

  1. Genome-derived insights into the biology of the hepatotoxic bloom-forming cyanobacterium Anabaena sp. strain 90

    Directory of Open Access Journals (Sweden)

    Wang Hao

    2012-11-01

    Full Text Available Abstract Background Cyanobacteria can form massive toxic blooms in fresh and brackish bodies of water and are frequently responsible for the poisoning of animals and pose a health risk for humans. Anabaena is a genus of filamentous diazotrophic cyanobacteria commonly implicated as a toxin producer in blooms in aquatic ecosystems throughout the world. The biology of bloom-forming cyanobacteria is poorly understood at the genome level. Results Here, we report the complete sequence and comprehensive annotation of the bloom-forming Anabaena sp. strain 90 genome. It comprises two circular chromosomes and three plasmids with a total size of 5.3 Mb, encoding a total of 4,738 genes. The genome is replete with mobile genetic elements. Detailed manual annotation demonstrated that almost 5% of the gene repertoire consists of pseudogenes. A further 5% of the genome is dedicated to the synthesis of small peptides that are the products of both ribosomal and nonribosomal biosynthetic pathways. Inactivation of the hassallidin (an antifungal cyclic peptide biosynthetic gene cluster through a deletion event and a natural mutation of the buoyancy-permitting gvpG gas vesicle gene were documented. The genome contains a large number of genes encoding restriction-modification systems. Two novel excision elements were found in the nifH gene that is required for nitrogen fixation. Conclusions Genome analysis demonstrated that this strain invests heavily in the production of bioactive compounds and restriction-modification systems. This well-annotated genome provides a platform for future studies on the ecology and biology of these important bloom-forming cyanobacteria.

  2. Characterisation of the paralytic shellfish toxin biosynthesis gene clusters in Anabaena circinalis AWQC131C and Aphanizomenon sp. NH-5

    Directory of Open Access Journals (Sweden)

    Neilan Brett A

    2009-03-01

    Full Text Available Abstract Background Saxitoxin and its analogues collectively known as the paralytic shellfish toxins (PSTs are neurotoxic alkaloids and are the cause of the syndrome named paralytic shellfish poisoning. PSTs are produced by a unique biosynthetic pathway, which involves reactions that are rare in microbial metabolic pathways. Nevertheless, distantly related organisms such as dinoflagellates and cyanobacteria appear to produce these toxins using the same pathway. Hypothesised explanations for such an unusual phylogenetic distribution of this shared uncommon metabolic pathway, include a polyphyletic origin, an involvement of symbiotic bacteria, and horizontal gene transfer. Results We describe the identification, annotation and bioinformatic characterisation of the putative paralytic shellfish toxin biosynthesis clusters in an Australian isolate of Anabaena circinalis and an American isolate of Aphanizomenon sp., both members of the Nostocales. These putative PST gene clusters span approximately 28 kb and contain genes coding for the biosynthesis and export of the toxin. A putative insertion/excision site in the Australian Anabaena circinalis AWQC131C was identified, and the organization and evolution of the gene clusters are discussed. A biosynthetic pathway leading to the formation of saxitoxin and its analogues in these organisms is proposed. Conclusion The PST biosynthesis gene cluster presents a mosaic structure, whereby genes have apparently transposed in segments of varying size, resulting in different gene arrangements in all three sxt clusters sequenced so far. The gene cluster organizational structure and sequence similarity seems to reflect the phylogeny of the producer organisms, indicating that the gene clusters have an ancient origin, or that their lateral transfer was also an ancient event. The knowledge we gain from the characterisation of the PST biosynthesis gene clusters, including the identity and sequence of the genes involved

  3. Reconstruction and comparison of the metabolic potential of cyanobacteria Cyanothece sp. ATCC 51142 and Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Saha, Rajib; Verseput, Alex T; Berla, Bertram M; Mueller, Thomas J; Pakrasi, Himadri B; Maranas, Costas D

    2012-01-01

    Cyanobacteria are an important group of photoautotrophic organisms that can synthesize valuable bio-products by harnessing solar energy. They are endowed with high photosynthetic efficiencies and diverse metabolic capabilities that confer the ability to convert solar energy into a variety of biofuels and their precursors. However, less well studied are the similarities and differences in metabolism of different species of cyanobacteria as they pertain to their suitability as microbial production chassis. Here we assemble, update and compare genome-scale models (iCyt773 and iSyn731) for two phylogenetically related cyanobacterial species, namely Cyanothece sp. ATCC 51142 and Synechocystis sp. PCC 6803. All reactions are elementally and charge balanced and localized into four different intracellular compartments (i.e., periplasm, cytosol, carboxysome and thylakoid lumen) and biomass descriptions are derived based on experimental measurements. Newly added reactions absent in earlier models (266 and 322, respectively) span most metabolic pathways with an emphasis on lipid biosynthesis. All thermodynamically infeasible loops are identified and eliminated from both models. Comparisons of model predictions against gene essentiality data reveal a specificity of 0.94 (94/100) and a sensitivity of 1 (19/19) for the Synechocystis iSyn731 model. The diurnal rhythm of Cyanothece 51142 metabolism is modeled by constructing separate (light/dark) biomass equations and introducing regulatory restrictions over light and dark phases. Specific metabolic pathway differences between the two cyanobacteria alluding to different bio-production potentials are reflected in both models.

  4. Reconstruction and comparison of the metabolic potential of cyanobacteria Cyanothece sp. ATCC 51142 and Synechocystis sp. PCC 6803.

    Directory of Open Access Journals (Sweden)

    Rajib Saha

    Full Text Available Cyanobacteria are an important group of photoautotrophic organisms that can synthesize valuable bio-products by harnessing solar energy. They are endowed with high photosynthetic efficiencies and diverse metabolic capabilities that confer the ability to convert solar energy into a variety of biofuels and their precursors. However, less well studied are the similarities and differences in metabolism of different species of cyanobacteria as they pertain to their suitability as microbial production chassis. Here we assemble, update and compare genome-scale models (iCyt773 and iSyn731 for two phylogenetically related cyanobacterial species, namely Cyanothece sp. ATCC 51142 and Synechocystis sp. PCC 6803. All reactions are elementally and charge balanced and localized into four different intracellular compartments (i.e., periplasm, cytosol, carboxysome and thylakoid lumen and biomass descriptions are derived based on experimental measurements. Newly added reactions absent in earlier models (266 and 322, respectively span most metabolic pathways with an emphasis on lipid biosynthesis. All thermodynamically infeasible loops are identified and eliminated from both models. Comparisons of model predictions against gene essentiality data reveal a specificity of 0.94 (94/100 and a sensitivity of 1 (19/19 for the Synechocystis iSyn731 model. The diurnal rhythm of Cyanothece 51142 metabolism is modeled by constructing separate (light/dark biomass equations and introducing regulatory restrictions over light and dark phases. Specific metabolic pathway differences between the two cyanobacteria alluding to different bio-production potentials are reflected in both models.

  5. High-yield production of extracellular type-I cellulose by the cyanobacterium Synechococcus sp. PCC 7002.

    Science.gov (United States)

    Zhao, Chi; Li, Zhongkui; Li, Tao; Zhang, Yingjiao; Bryant, Donald A; Zhao, Jindong

    2015-01-01

    Cellulose synthase, encoded by the cesA gene, is responsible for the synthesis of cellulose in nature. We show that the cell wall of the cyanobacterium Synechococcus sp. PCC 7002 naturally contains cellulose. Cellulose occurs as a possibly laminated layer between the inner and outer membrane, as well as being an important component of the extracellular glycocalyx in this cyanobacterium. Overexpression of six genes, cmc-ccp-cesAB-cesC-cesD-bgl, from Gluconacetobacter xylinus in Synechococcus sp. PCC 7002 resulted in very high-yield production of extracellular type-I cellulose. High-level cellulose production only occurred when the native cesA gene was inactivated and when cells were grown at low salinity. This system provides a method for the production of lignin-free cellulose from sunlight and CO2 for biofuel production and other biotechnological applications.

  6. Flux coupling and transcriptional regulation within the metabolic network of the photosynthetic bacterium Synechocystis sp. PCC6803

    DEFF Research Database (Denmark)

    Montagud, Arnau; Zelezniak, Aleksej; Navarro, Emilio

    2011-01-01

    activities and metabolic physiology, flux coupling analysis was performed for iSyn811 under four different growth conditions, viz., autotrophy, mixotrophy, heterotrophy, and light-activated heterotrophy (LH). Initial steps of carbon acquisition and catabolism formed the versatile center of the flux coupling...... and reporter flux coupling groups - regulatory hot spots during metabolic shifts triggered by the availability of light. Overall, flux coupling analysis provided insight into the structural organization of Synechocystis sp. PCC6803 metabolic network toward designing of a photosynthesis-based production......-scale metabolic model is a pre-requisite toward achieving a proficient photosynthetic cell factory. To this end, we report iSyn811, an upgraded genome-scale metabolic model of Synechocystis sp. PCC6803 consisting of 956 reactions and accounting for 811 genes. To gain insights into the interplay between flux...

  7. High-yield production of extracellular type-I cellulose by the cyanobacterium Synechococcus sp. PCC 7002

    OpenAIRE

    Zhao, Chi; Li,Zhongkui; Li, Tao; Zhang, Yingjiao; Bryant, Donald A.; Zhao, Jindong

    2015-01-01

    Cellulose synthase, encoded by the cesA gene, is responsible for the synthesis of cellulose in nature. We show that the cell wall of the cyanobacterium Synechococcus sp. PCC 7002 naturally contains cellulose. Cellulose occurs as a possibly laminated layer between the inner and outer membrane, as well as being an important component of the extracellular glycocalyx in this cyanobacterium. Overexpression of six genes, cmc–ccp–cesAB–cesC–cesD–bgl, from Gluconacetobacter xylinus in Synechococcus s...

  8. An Integrative Approach to Energy, Carbon, and Redox Metabolism in the Cyanobacterium Synechocystis sp. PCC 6803. Special Report

    Energy Technology Data Exchange (ETDEWEB)

    Overbeek, R.

    2003-06-30

    The main objectives for the first year were to produce a detailed metabolic reconstruction of synechocystis sp. PCC 6803 especially in interrelated areas of photosynthesis, respiration, and central carbon metabolism to support a more complete understanding and modeling of this organism. Additionally, Integrated Genomics, Inc., provided detailed bioinformatic analysis of selected functional systems related to carbon and energy generation and utilization, and of the corresponding pathways, functional roles and individual genes to support wet lab experiments by collaborators.

  9. Metabolic engineering of enhanced glycerol-3-phosphate synthesis to increase lipid production in Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Wang, Xi; Xiong, Xiaochao; Sa, Na; Roje, Sanja; Chen, Shulin

    2016-07-01

    With the growing attention to global warming and energy sustainability, biosynthesis of lipids by photosynthetic microorganisms has attracted more interest for the production of renewable transportation fuels. Recently, the cyanobacterium Synechocystis sp. PCC 6803 has been widely used for biofuel production through metabolic engineering because of its efficient photosynthesis and well-developed genetic tools. In lipid biosynthesis, glycerol-3-phosphate (G3P) is a key node for both CO2 fixation and lipid metabolism in cyanobacteria. However, few studies have explored the use of G3P synthesis to improve photosynthetic lipid production. In this study, metabolic engineering combined with flux balance analysis (FBA) was conducted to reveal the effect of G3P synthesis on lipid production. Heterologous genes that encoded glycerol-3-phosphate dehydrogenase (GPD) and diacylglycerol acyltransferase (DGAT) were engineered into Synechocystis sp. PCC 6803 to enhance G3P supply and lipid production. The resultant recombinant Synechocystis produced higher levels of lipids without a significant reduction in cell growth. Compared with the wild-type strain, lipid content and productivity of the engineered cyanobacteria increased by up to 36 and 31 %, respectively, under autotrophic conditions. Lipid production under mixotrophic conditions of the engineered cyanobacteria was also investigated. This work demonstrated that enhanced G3P synthesis was an important factor in photosynthetic lipid production and that introducing heterologous GPD and DGAT genes was an effective strategy to increase lipid production in Synechocystis sp. PCC 6803.

  10. Metabolic Engineering of Synechocystis sp. PCC 6803 for Production of the Plant Diterpenoid Manoyl Oxide.

    Science.gov (United States)

    Englund, Elias; Andersen-Ranberg, Johan; Miao, Rui; Hamberger, Björn; Lindberg, Pia

    2015-12-18

    Forskolin is a high value diterpenoid with a broad range of pharmaceutical applications, naturally found in root bark of the plant Coleus forskohlii. Because of its complex molecular structure, chemical synthesis of forskolin is not commercially attractive. Hence, the labor and resource intensive extraction and purification from C. forskohlii plants remains the current source of the compound. We have engineered the unicellular cyanobacterium Synechocystis sp. PCC 6803 to produce the forskolin precursor 13R-manoyl oxide (13R-MO), paving the way for light driven biotechnological production of this high value compound. In the course of this work, a new series of integrative vectors for use in Synechocystis was developed and used to create stable lines expressing chromosomally integrated CfTPS2 and CfTPS3, the enzymes responsible for the formation of 13R-MO in C. forskohlii. The engineered strains yielded production titers of up to 0.24 mg g(-1) DCW 13R-MO. To increase the yield, 13R-MO producing strains were further engineered by introduction of selected enzymes from C. forskohlii, improving the titer to 0.45 mg g(-1) DCW. This work forms a basis for further development of production of complex plant diterpenoids in cyanobacteria.

  11. Spectral properties of a divinyl chlorophyll a harboring mutant of Synechocystis sp. PCC6803.

    Science.gov (United States)

    Islam, Md Rafiqul; Watanabe, Koji; Kashino, Yasuhiro; Satoh, Kazuhiko; Koike, Hiroyuki

    2013-11-01

    A divinyl chlorophyll (DV-Chl) a harboring mutant of Synechocystis sp. PCC 6803, in which chlorophyll species is replaced from monovinyl(normal)-Chl a to DV-Chl a, was characterized. The efficiency of light utilization for photosynthesis was decreased in the mutant. Absorption spectra at 77 K and their fourth derivative analyses revealed that peaks of each chlorophyll forms were blue-shifted by 1-2 nm, suggesting lowered stability of chlorophylls at their binding sites. This was also true both in PSI and PSII complexes. On the other hand, fluorescence emission spectra measured at 77 K were not different between wild type and the mutant. This indicates that the mode of interaction between chlorophyll and its binding pockets responsible for emitting fluorescence at 77 K is not altered in the mutant. P700 difference spectra of thylakoid membranes and PSI complexes showed that the spectrum in Soret region was red-shifted by 7 nm in the mutant. This is a characteristic feature of DV-Chl a. Microenvironments of iron-sulfur center of a terminal electron acceptor of PSI complex, P430, were practically the same as that of wild type.

  12. Engineering of genetic control tools in Synechocystis sp. PCC 6803 using rational design techniques.

    Science.gov (United States)

    Albers, Stevan C; Gallegos, Victor A; Peebles, Christie A M

    2015-12-20

    Cyanobacteria show promise as photosynthetic microbial factories capable of harnessing sunlight and CO2 to produce valuable end products, but few genetic control tools have been characterized and utilized in these organisms. To develop a suite of control elements capable of gene control at a variety of expression strengths, a library of 10 promoter-constructs were developed and built via rational design techniques by adding individual nucleotides in a step-wise manner within the -10 and -35 cis-acting regions of the tac promoter. This suite produced a dynamic range of expression strength, exhibiting a 78 fold change between the lowest expressing promoter, Psca8- and the highest expressing promoter, Psca3-2 when tested within Synechocystis sp. PCC 6803. Additionally, this study details the construction of a chemically inducible construct for use in Synechocystis that is based on the tac repressor system most commonly used in Escherichia coli. This research demonstrates the construction of a highly expressed inducible promoter that is also capable of high levels of gene repression. Upon chemical induction with IPTG, this same mutant strain was capable of exhibiting an average 24X increase in GFP expression over that of the repressed state.

  13. Studies on Hemolysis of Hemolysin Produced by Synechocystis sp.PCC 6803

    Institute of Scientific and Technical Information of China (English)

    BI Shuai; WANG Wei; ZHAO Yuanyuan; RU Shaoguo; LIU Yunzhang

    2011-01-01

    Hemolysin produced by various bacteria,may destroy erythrocyte membranes via a pore-forming mechanism,a detergent action,or a lipase activity.Previous to this experiment,the mode of action used by cyanobacterial hemolysin had not been reported.To characterize the action mode of hemolysin produced by the wild-type strain of Synechocystis sp.PCC6803,hemolysis of erythrocytes originating from human,mouse,sheep,rabbit and goldfish was studied.The erythrocytes of mouse,sheep and rabbit were sensitive,while those of human and fish were resistant,to this hemolysin.Using rabbit erythrocytes,it was shown that hemolysis occurred in two steps:a binding step within the first 10min of treatment and a lyric step after 30 min.Both binding and lysis were highly temperature-dependent.Effects of erythrocyte density on hemolysis suggest that the hemolysin might target erythrocytes via a multiple-hit mechanism.In the osmotic protection experiment,all tested osmotic protectants,with molecular diameters ranging from 0.9-5.66 nm,failed to effectively inhibit hemolysis.Scanning electron micrographs showed that the hemolysin caused protuberances or echinocytes in rabbit erythrocytes,and then disrupted and ruptured the erythrocytes.Characteristics of hemolysis showed distinct differences from other pore-forming mechanisms,suggesting that this hemolysin might act through a detergent-like or lipase mechanism,rather than a pore-forming mechanism.

  14. Integrated metabolic flux and omics analysis of Synechocystis sp. PCC 6803 under mixotrophic and photoheterotrophic conditions.

    Science.gov (United States)

    Nakajima, Tsubasa; Kajihata, Shuichi; Yoshikawa, Katsunori; Matsuda, Fumio; Furusawa, Chikara; Hirasawa, Takashi; Shimizu, Hiroshi

    2014-09-01

    Cyanobacteria have flexible metabolic capability that enables them to adapt to various environments. To investigate their underlying metabolic regulation mechanisms, we performed an integrated analysis of metabolic flux using transcriptomic and metabolomic data of a cyanobacterium Synechocystis sp. PCC 6803, under mixotrophic and photoheterotrophic conditions. The integrated analysis indicated drastic metabolic flux changes, with much smaller changes in gene expression levels and metabolite concentrations between the conditions, suggesting that the flux change was not caused mainly by the expression levels of the corresponding genes. Under photoheterotrophic conditions, created by the addition of the photosynthesis inhibitor atrazine in mixotrophic conditions, the result of metabolic flux analysis indicated the significant repression of carbon fixation and the activation of the oxidative pentose phosphate pathway (PPP). Moreover, we observed gluconeogenic activity of upstream of glycolysis, which enhanced the flux of the oxidative PPP to compensate for NADPH depletion due to the inhibition of the light reaction of photosynthesis. 'Omics' data suggested that these changes were probably caused by the repression of the gap1 gene, which functions as a control valve in the metabolic network. Since metabolic flux is the outcome of a complicated interplay of cellular components, integrating metabolic flux with other 'omics' layers can identify metabolic changes and narrow down these regulatory mechanisms more effectively.

  15. Phycobilisome truncation causes widespread proteome changes in Synechocystis sp. PCC 6803

    Science.gov (United States)

    Liberton, Michelle; Chrisler, William B.; Nicora, Carrie D.; Moore, Ronald J.; Smith, Richard D.; Koppenaal, David W.; Pakrasi, Himadri B.; Jacobs, Jon M.

    2017-01-01

    In cyanobacteria such as Synechocystis sp. PCC 6803, large antenna complexes called phycobilisomes (PBS) harvest light and transfer the energy to the photosynthetic reaction centers. Modification of the light harvesting machinery in cyanobacteria has widespread consequences, causing changes in cell morphology and physiology. In the current study, we investigated the effects of PBS truncation on the proteomes of three Synechocystis 6803 PBS antenna mutants. These range from the progressive truncation of phycocyanin rods in the CB and CK strains, to full removal of PBS in the PAL mutant. Comparative quantitative protein results revealed surprising changes in protein abundances in the mutant strains. Our results showed that PBS truncation in Synechocystis 6803 broadly impacted core cellular mechanisms beyond light harvesting and photosynthesis. Specifically, we observed dramatic alterations in membrane transport mechanisms, where the most severe PBS truncation in the PAL strain appeared to suppress the cellular utilization and regulation of bicarbonate and iron. These changes point to the role of PBS as a component critical to cell function, and demonstrate the continuing need to assess systems-wide protein based abundances to understand potential indirect phenotypic effects. PMID:28253354

  16. Computational evaluation of Synechococcus sp. PCC 7002 metabolism for chemical production

    Energy Technology Data Exchange (ETDEWEB)

    Vu, Trang; Hill, Eric A.; Kucek, Leo A.; Konopka, Allan; Beliaev, Alex S.; Reed, Jennifer L.

    2013-05-24

    Cyanobacteria are ideal metabolic engineering platforms for carbon-neutral biotechnology because they directly convert CO2 to a range of valuable products. In this study, we present a computational assessment of biochemical production in Synechococcus sp. PCC 7002 (Synechococcus 7002), a fast growing cyanobacterium whose genome has been sequenced, and for which genetic modification methods have been developed. We evaluated the maximum theoretical yields (mol product per mol CO2 or mol photon) of producing various chemicals under photoautotrophic and dark conditions using a genome-scale metabolic model of Synechococcus 7002. We found that the yields were lower under dark conditions, compared to photoautotrophic conditions, due to the limited amount of energy and reductant generated from glycogen. We also examined the effects of photon and CO2 limitations on chemical production under photoautotrophic conditions. In addition, using various computational methods such as MOMA, RELATCH, and OptORF, we identified gene-knockout mutants that are predicted to improve chemical production under photoautotrophic and/or dark anoxic conditions. These computational results are useful for metabolic engineering of cyanobacteria to synthesize valueadded products.

  17. Flux balance analysis of cyanobacterial metabolism: the metabolic network of Synechocystis sp. PCC 6803.

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    Henning Knoop

    Full Text Available Cyanobacteria are versatile unicellular phototrophic microorganisms that are highly abundant in many environments. Owing to their capability to utilize solar energy and atmospheric carbon dioxide for growth, cyanobacteria are increasingly recognized as a prolific resource for the synthesis of valuable chemicals and various biofuels. To fully harness the metabolic capabilities of cyanobacteria necessitates an in-depth understanding of the metabolic interconversions taking place during phototrophic growth, as provided by genome-scale reconstructions of microbial organisms. Here we present an extended reconstruction and analysis of the metabolic network of the unicellular cyanobacterium Synechocystis sp. PCC 6803. Building upon several recent reconstructions of cyanobacterial metabolism, unclear reaction steps are experimentally validated and the functional consequences of unknown or dissenting pathway topologies are discussed. The updated model integrates novel results with respect to the cyanobacterial TCA cycle, an alleged glyoxylate shunt, and the role of photorespiration in cellular growth. Going beyond conventional flux-balance analysis, we extend the computational analysis to diurnal light/dark cycles of cyanobacterial metabolism.

  18. Respiration accumulates Calvin cycle intermediates for the rapid start of photosynthesis in Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Shimakawa, Ginga; Hasunuma, Tomohisa; Kondo, Akihiko; Matsuda, Mami; Makino, Amane; Miyake, Chikahiro

    2014-01-01

    We tested the hypothesis that inducing photosynthesis in cyanobacteria requires respiration. A mutant deficient in glycogen phosphorylase (∆GlgP) was prepared in Synechocystis sp. PCC 6803 to suppress respiration. The accumulated glycogen in ΔGlgP was 250-450% of that accumulated in wild type (WT). The rate of dark respiration in ΔGlgP was 25% of that in WT. In the dark, P700(+) reduction was suppressed in ΔGlgP, and the rate corresponded to that in (2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone)-treated WT, supporting a lower respiration rate in ∆GlgP. Photosynthetic O2-evolution rate reached a steady-state value much slower in ∆GlgP than in WT. This retardation was solved by addition of d-glucose. Furthermore, we found that the contents of Calvin cycle intermediates in ∆GlgP were lower than those in WT under dark conditions. These observations indicated that respiration provided the carbon source for regeneration of ribulose 1,5-bisphosphate in order to drive the rapid start of photosynthesis.

  19. Metabolic flux analysis of the hydrogen production potential in Synechocystis sp. PCC6803

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, E. [Departamento de Lenguajes y Ciencias de la Computacion, Campus de Teatrinos, Universidad de Malaga, 29071 Malaga (Spain); Montagud, A.; Fernandez de Cordoba, P.; Urchueguia, J.F. [Instituto Universitario de Matematica Pura y Aplicada, Universidad Politecnica de Valencia, Camino de Vera 14, 46022 Valencia (Spain)

    2009-11-15

    Hydrogen is a promising energy vector; however, finding methods to produce it from renewable sources is essential to allow its wide-scale use. In that line, biological hydrogen production, although it is considered as a possible alternative, requires substantial improvements to overcome its present low yields. In that direction, genetic manipulation probably will play a central role and from that point of view metabolic flux analysis (MFA) constitutes an important tool to guide a priori most suitable genetic modifications oriented to a hydrogen yield increase. In this work MFA has been applied to analyze hydrogen photoproduction of Synechocystis sp. PCC6803. Flux analysis was carried out based on literature data and several basic fluxes were estimated in different growing conditions of the system. From this analysis, an upper limit for hydrogen photoproduction has been determined indicating a wide margin for improvement. MFA was also used to find a feasible operating space for hydrogen production, which avoids oxygen inhibition, one of the most important limitations to make hydrogen production cost effective. In addition, a set of biotechnological strategies are proposed that would be consistent with the performed mathematical analysis. (author)

  20. Functional Diversity of Transcriptional Regulators in the Cyanobacterium Synechocystis sp. PCC 6803

    Science.gov (United States)

    Shi, Mengliang; Zhang, Xiaoqing; Pei, Guangsheng; Chen, Lei; Zhang, Weiwen

    2017-01-01

    Functions of transcriptional regulators (TRs) are still poorly understood in the model cyanobacterium Synechocystis sp. PCC 6803. To address the issue, we constructed knockout mutants for 32 putative TR-encoding genes of Synechocystis, and comparatively analyzed their phenotypes under autotrophic growth condition and metabolic profiles using liquid chromatography-mass spectrometry-based metabolomics. The results showed that only four mutants of TR genes, sll1872 (lytR), slr0741 (phoU), slr0395 (ntcB), and slr1871 (pirR), showed differential growth patterns in BG11 medium when compared with the wild type; however, in spite of no growth difference observed for the remaining TR mutants, metabolomic profiling showed that they were different at the metabolite level, suggesting significant functional diversity of TRs in Synechocystis. In addition, an integrative metabolomic and gene families’ analysis of all TR mutants led to the identification of five pairs of TR genes that each shared close relationship in both gene families and metabolomic clustering trees, suggesting possible conserved functions of these TRs during evolution. Moreover, more than a dozen pairs of TR genes with different origin and evolution were found with similar metabolomic profiles, suggesting a possible functional convergence of the TRs during genome evolution. Finally, a protein–protein network analysis was performed to predict regulatory targets of TRs, allowing inference of possible regulatory gene targets for 4 out of five pairs of TRs. This study provided new insights into the regulatory functions and evolution of TR genes in Synechocystis. PMID:28270809

  1. Oxygen-responsive genetic circuits constructed in Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Immethun, Cheryl M; Ng, Kenneth M; DeLorenzo, Drew M; Waldron-Feinstein, Ben; Lee, Ying-Chiang; Moon, Tae Seok

    2016-02-01

    As photoautotrophic prokaryotes, cyanobacteria are promising platforms for producing value-added bioproducts. However, few regulatory genetic parts and devices (e.g., inducible promoters and regulatory circuits) have been developed for these potential hosts. Furthermore, the devices that have been created respond only to a single input. To address these issues, we developed an inducible genetic circuit that generates heterologous proteins in response to oxygen, an environmental signal. To test its performance and utility in Synechocystis sp. PCC 6803, a model cyanobacterial strain, we connected this circuit to either heterologous nifHDK genes, which encode oxygen-sensitive nitrogenase's structural proteins, or a fluorescent protein gene. The circuit was transcriptionally activated to generate nifHDK transcripts or fluorescent output only in low oxygen conditions. We expanded the oxygen-responsive circuit into a more complex circuit by building a two-input AND gate, which allows Synechocystis to specifically control expression of the fluorescent reporter in response to two signals, low oxygen and high anhydrotetracycline. To our knowledge, the AND gate is the first complex logic circuit built in a cyanobacterial strain. This work expands the synthetic biology tools available for complex gene expression in cyanobacteria, increasing their potential as biotechnology platforms.

  2. Fur-type transcriptional repressors and metal homeostasis in the cyanobacterium Synechococcus sp. PCC 7002

    Directory of Open Access Journals (Sweden)

    Marcus eLudwig

    2015-10-01

    Full Text Available Metal homeostasis is a crucial cellular function for nearly all organisms. Some heavy metals (e.g. Fe, Zn, Co, Mo are essential because they serve as cofactors for enzymes or metalloproteins, and chlorophototrophs such as cyanobacteria have an especially high demand for iron. At excessive levels, however, metals become toxic to cyanobacteria. Therefore, a tight control mechanism is essential for metal homeostasis. Metal homeostasis in microorganisms comprises two elements: metal acquisition from the environment and detoxification or excretion of excess metal ions. Different families of metal-sensing regulators exist in cyanobacteria and each addresses a more or less specific set of target genes. In this study the regulons of three Fur-type and two ArsR-SmtB-type regulators were investigated in a comparative approach in the cyanobacterium Synechococcus sp. PCC 7002. One Fur-type regulator controls genes for iron acquisition (Fur; one controls genes for zinc acquisition (Zur; and the third controls two genes involved in oxidative stress (Per. Compared to other well-investigated cyanobacterial strains, however, the set of target genes for each regulator is relatively small. Target genes for the two ArsR-SmtB transcriptional repressors (SmtB (SYNPCC7002_A2564 and SYNPCC7002_A0590; ArsR are involved in zinc homeostasis in addition to Zur. Their target genes, however, are less specific for zinc and point to roles in a broader heavy metal detoxification response.

  3. Refolding and enzyme kinetic studies on the ferrochelatase of the cyanobacterium Synechocystis sp. PCC 6803.

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    Patrik Storm

    Full Text Available Heme is a cofactor for proteins participating in many important cellular processes, including respiration, oxygen metabolism and oxygen binding. The key enzyme in the heme biosynthesis pathway is ferrochelatase (protohaem ferrolyase, EC 4.99.1.1, which catalyzes the insertion of ferrous iron into protoporphyrin IX. In higher plants, the ferrochelatase enzyme is localized not only in mitochondria, but also in chloroplasts. The plastidic type II ferrochelatase contains a C-terminal chlorophyll a/b (CAB motif, a conserved hydrophobic stretch homologous to the CAB domain of plant light harvesting proteins and light-harvesting like proteins. This type II ferrochelatase, found in all photosynthetic organisms, is presumed to have evolved from the cyanobacterial ferrochelatase. Here we describe a detailed enzymological study on recombinant, refolded and functionally active type II ferrochelatase (FeCh from the cyanobacterium Synechocystis sp. PCC 6803. A protocol was developed for the functional refolding and purification of the recombinant enzyme from inclusion bodies, without truncation products or soluble aggregates. The refolded FeCh is active in its monomeric form, however, addition of an N-terminal His(6-tag has significant effects on its enzyme kinetics. Strikingly, removal of the C-terminal CAB-domain led to a greatly increased turnover number, k(cat, compared to the full length protein. While pigments isolated from photosynthetic membranes decrease the activity of FeCh, direct pigment binding to the CAB domain of FeCh was not evident.

  4. Refolding and enzyme kinetic studies on the ferrochelatase of the cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Storm, Patrik; Tibiletti, Tania; Hall, Michael; Funk, Christiane

    2013-01-01

    Heme is a cofactor for proteins participating in many important cellular processes, including respiration, oxygen metabolism and oxygen binding. The key enzyme in the heme biosynthesis pathway is ferrochelatase (protohaem ferrolyase, EC 4.99.1.1), which catalyzes the insertion of ferrous iron into protoporphyrin IX. In higher plants, the ferrochelatase enzyme is localized not only in mitochondria, but also in chloroplasts. The plastidic type II ferrochelatase contains a C-terminal chlorophyll a/b (CAB) motif, a conserved hydrophobic stretch homologous to the CAB domain of plant light harvesting proteins and light-harvesting like proteins. This type II ferrochelatase, found in all photosynthetic organisms, is presumed to have evolved from the cyanobacterial ferrochelatase. Here we describe a detailed enzymological study on recombinant, refolded and functionally active type II ferrochelatase (FeCh) from the cyanobacterium Synechocystis sp. PCC 6803. A protocol was developed for the functional refolding and purification of the recombinant enzyme from inclusion bodies, without truncation products or soluble aggregates. The refolded FeCh is active in its monomeric form, however, addition of an N-terminal His(6)-tag has significant effects on its enzyme kinetics. Strikingly, removal of the C-terminal CAB-domain led to a greatly increased turnover number, k(cat), compared to the full length protein. While pigments isolated from photosynthetic membranes decrease the activity of FeCh, direct pigment binding to the CAB domain of FeCh was not evident.

  5. Genomic responses to arsenic in the cyanobacterium Synechocystis sp. PCC 6803.

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    Ana María Sánchez-Riego

    Full Text Available Arsenic is a ubiquitous contaminant and a toxic metalloid which presents two main redox states in nature: arsenite [As(III] and arsenate [As(V]. Arsenic resistance in Synechocystis sp. strain PCC 6803 is mediated by the arsBHC operon and two additional arsenate reductases encoded by the arsI1 and arsI2 genes. Here we describe the genome-wide responses to the presence of arsenate and arsenite in wild type and mutants in the arsenic resistance system. Both forms of arsenic produced similar responses in the wild type strain, including induction of several stress related genes and repression of energy generation processes. These responses were transient in the wild type strain but maintained in time in an arsB mutant strain, which lacks the arsenite transporter. In contrast, the responses observed in a strain lacking all arsenate reductases were somewhat different and included lower induction of genes involved in metal homeostasis and Fe-S cluster biogenesis, suggesting that these two processes are targeted by arsenite in the wild type strain. Finally, analysis of the arsR mutant strain revealed that ArsR seems to only control 5 genes in the genome. Furthermore, the arsR mutant strain exhibited hypersentivity to nickel, copper and cadmium and this phenotype was suppressed by mutation in arsB but not in arsC gene suggesting that overexpression of arsB is detrimental in the presence of these metals in the media.

  6. 无机盐诱导鱼腥藻 595 (Anabaena sp.595)的细胞学效应%The Cellular Effect of Anabaena sp.595 Induced by Inorganic Salts

    Institute of Scientific and Technical Information of China (English)

    吴红艳; 赵以军; 郭厚良; 张婷; 吴涛

    2003-01-01

    鱼腥藻 595 (Anabaena sp. 595)在0.05 mol/L钾、钠、铵的盐酸盐、硝酸盐、硫酸盐和磷酸盐的诱导下,2 d后即出现显著的细胞学效应:细胞体积增大,明显液泡化;少数细胞发生横向和不均等分裂;藻丝片段化,异形胞分化率相对提高.其中,铵盐培养的藻丝细胞内出现特异的浓缩颗粒状区域.钙盐、镁盐也诱导类似细胞学变化,但作用较弱.在含0.1 mol/L NaCl的培养基中长期培养,细胞出现周期性分化行为,开始细胞膨大并液泡化,以后色素质重新充满细胞,液泡消失,然后细胞分裂至正常细胞大小,成为接近正常的藻丝,但接着又膨大液泡化,如此进入新的周期过程.

  7. Production of γ-linolenic acid and stearidonic acid by Synechococcus sp. PCC7002 containing cyanobacterial fatty acid desaturase genes

    Science.gov (United States)

    Dong, Xuewei; He, Qingfang; Peng, Zhenying; Yu, Jinhui; Bian, Fei; Li, Youzhi; Bi, Yuping

    2016-07-01

    Genetic modification is useful for improving the nutritional qualities of cyanobacteria. To increase the total unsaturated fatty acid content, along with the ratio of ω-3/ω-6 fatty acids, genetic engineering can be used to modify fatty acid metabolism. Synechococcus sp. PCC7002, a fast-growing cyanobacterium, does not contain a Δ6 desaturase gene and is therefore unable to synthesize γ-linolenic acid (GLA) and stearidonic acid (SDA), which are important in human health. In this work, we constructed recombinant vectors Syd6D, Syd15D and Syd6Dd15D to express the Δ15 desaturase and Δ6 desaturase genes from Synechocystis PCC6803 in Synechococcus sp. PCC7002, with the aim of expressing polyunsaturated fatty acids. Overexpression of the Δ15 desaturase gene in Synechococcus resulted in 5.4 times greater accumulation of α-linolenic acid compared with the wild-type while Δ6 desaturase gene expression produced both GLA and SDA. Co-expression of the two genes resulted in low-level accumulation of GLA but much larger amounts of SDA, accounting for as much to 11.64% of the total fatty acid content.

  8. 维生素对转基因鱼腥藻Anabaena sp.PCC7120培养的影响%EFFECT OF VITAMIN ON CULTURE OF RECOMBINANT ANABAENA sp.PCC7120

    Institute of Scientific and Technical Information of China (English)

    刘志伟; 张晨; 郭勇

    2002-01-01

    @@ 近年来分子遗传学和基因工程研究证实,大肠杆菌的载体和启动子往往可以适用于蓝藻,尤其是单细胞蓝藻的转基因,这使得蓝藻基因工程得到了较快的发展,利用藻类为宿主的基因产物的生产也受到日益关注,因此微藻的培养受到广泛重视.刘凤龙等通过三亲结合转移方式将人TNF-α基因转入鱼腥藻7120中并得到表达[1],但转基因鱼腥藻高效培养方面需进一步研究.

  9. Interplay between flavodiiron proteins and photorespiration in Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Allahverdiyeva, Yagut; Ermakova, Maria; Eisenhut, Marion; Zhang, Pengpeng; Richaud, Pierre; Hagemann, Martin; Cournac, Laurent; Aro, Eva-Mari

    2011-07-08

    Flavodiiron (Flv) proteins are involved in detoxification of O(2) and NO in anaerobic bacteria and archaea. Cyanobacterial Flv proteins, on the contrary, function in oxygenic environment and possess an extra NAD(P)H:flavin oxidoreductase module. Synechocystis sp. PCC 6803 has four genes (sll1521, sll0219, sll0550, and sll0217) encoding Flv proteins (Flv1, Flv2, Flv3, and Flv4). Previous in vitro studies with recombinant Flv3 protein from Synechocystis provided evidence that it functions as a NAD(P)H:oxygen oxidoreductase, and subsequent in vivo studies with Synechocystis confirmed the role of Flv1 and Flv3 proteins in the Mehler reaction (photoreduction of O(2) to H(2)O). Interestingly, homologous proteins to Flv1 and Flv3 can be found also in green algae, mosses, and Selaginella. Here, we addressed the function of Flv1 and Flv3 in Synechocystis using the Δflv1, Δflv3, and Δflv1/Δflv3 mutants and applying inorganic carbon (C(i))-deprivation conditions. We propose that only the Flv1/Flv3 heterodimer form is functional in the Mehler reaction in vivo. (18)O(2) labeling was used to discriminate between O(2) evolution in photosynthetic water splitting and O(2) consumption. In wild type, ∼20% of electrons originated from water was targeted to O(2) under air level CO(2) conditions but increased up to 60% in severe limitation of C(i). Gas exchange experiments with Δflv1, Δflv3, and Δflv1/Δflv3 mutants demonstrated that a considerable amount of electrons in these mutants is directed to photorespiration under C(i) deprivation. This assumption is in line with increased transcript abundance of photorespiratory genes and accumulation of photorespiratory intermediates in the WT and to a higher extent in mutant cells under C(i) deprivation.

  10. Lauric acid production in a glycogen-less Synechococcus sp. PCC 7002 mutant

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    Victoria H. Work

    2015-04-01

    Full Text Available The cyanobacterium Synechococcus sp. PCC 7002 was genetically engineered to synthesize biofuel compatible medium-chain fatty acids during photoautotrophic growth. Expression of a heterologous lauroyl-acyl carrier protein (C12:0-ACP thioesterase with concurrent deletion of the endogenous putative acyl-ACP synthetase led to secretion of transesterifiable C12:0 fatty acid in CO2-supplemented batch cultures. When grown at steady state over a range of light intensities in an LED turbidostat photobioreactor, the C12-secreting mutant exhibited a modest reduction in growth rate and increased O2 evolution relative to the wildtype. Inhibition of i glycogen synthesis by deletion of the glgC-encoded ADP-glucose pyrophosphorylase (AGPase, and ii protein synthesis by nitrogen deprivation were investigated as potential mechanisms for metabolite redistribution to increase fatty acid synthesis. Deletion of AGPase led to a ten-fold decrease in reducing carbohydrates and secretion of organic acids during nitrogen deprivation consistent with an energy spilling phenotype. When the carbohydrate-deficient background (∆glgC was modified for C12 secretion, no increase in C12 was achieved during nutrient replete growth, and no C12 was recovered from any strain upon nitrogen deprivation under the conditions used. At steady state, the growth rate of the ∆glgC strain saturated at a lower light intensity than the wildtype, but O2 evolution was not compromised and became increasingly decoupled from growth rate with rising irradiance. Photophysiological properties of the ∆glgC strain suggest energy dissipation from photosystem II and reconfiguration of electron flow at the level of the plastoquinone pool.

  11. Phosphoproteome of the cyanobacterium Synechocystis sp. PCC 6803 and its dynamics during nitrogen starvation.

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    Philipp eSpät

    2015-03-01

    Full Text Available Cyanobacteria have shaped the earth’s biosphere as the first oxygenic photoautotrophs and still play an important role in many ecosystems. The ability to adapt to changing environmental conditions is an essential characteristic in order to ensure survival. To this end, numerous studies have shown that bacteria use protein post-translational modifications such as Ser/Thr/Tyr phosphorylation in cell signalling, adaptation and regulation. Nevertheless, our knowledge of cyanobacterial phosphoproteomes and their dynamic response to environmental stimuli is relatively limited. In this study, we applied gel-free methods and high accuracy mass spectrometry towards the unbiased detection of Ser/Thr/Tyr phosphorylation events in the model cyanobacterium Synechocystis sp. PCC 6803. We could identify over 300 phosphorylation events in cultures grown on nitrate as exclusive nitrogen source. Chemical dimethylation labelling was applied to investigate proteome and phosphoproteome dynamics during nitrogen starvation. Our dataset describes the most comprehensive (phosphoproteome of Synechocystis to date, identifying 2,382 proteins and 183 phosphorylation events and quantifying 2,111 proteins and 148 phosphorylation events during nitrogen starvation. Global protein phosphorylation levels were increased in response to nitrogen depletion after 24 hours. Among the proteins with increased phosphorylation, the PII signalling protein showed the highest fold-change, serving as positive control. Other proteins with increased phosphorylation levels comprised functions in photosynthesis and in carbon and nitrogen metabolism. This study reveals dynamics of Synechocystis phosphoproteome in response to environmental stimuli and suggests an important role of protein Ser/Thr/Tyr phosphorylation in fundamental mechanisms of homeostatic control in cyanobacteria.

  12. Crystal structure of dimeric heme oxygenase-2 from Synechocystis sp. PCC 6803 in complex with heme.

    Science.gov (United States)

    Sugishima, Masakazu; Hagiwara, Yoshinori; Zhang, Xuhong; Yoshida, Tadashi; Migita, Catharina T; Fukuyama, Keiichi

    2005-03-22

    Phycobiliproteins, light-harvesting proteins in cyanobacteria, red algae, and cryptophytes, contain phycobilin pigments. Phycobilins are synthesized from biliverdin, which is produced by the oxidative cleavage of the heme porphyrin ring catalyzed by heme oxygenase (HO). Two paralogs of ho (ho1 and ho2) have been identified in the genome of the cyanobacterium, Synechocystis sp. PCC 6803. The recombinant proteins of both paralogs (Syn HO-1 and Syn HO-2) possess in vitro heme degradation activity. We have determined the crystal structures of Syn HO-2 in complex with heme (heme-Syn HO-2) and its reduced and NO bound forms. The heme-Syn HO-2 crystal was a nonmerohedral twin, and detwinned diffraction data were used to refine the structure. Although heme-Syn HO-2 shares common folding with other HOs, the C-terminal segment is ordered and turns back to the heme-binding side. Gel-filtration chromatography analysis and molecular packing in the crystal indicate that heme-Syn HO-2 forms a homodimer, in which the C-terminal ordered segments interact with each other. Because Syn HO-2 is a monomer in the apo state, the dimeric interaction may aid in the selection of the reducing partner but likely does not interfere with heme binding. The heme iron is coordinated by a water molecule in the ferric form, but the distal water is absent in the ferrous form. In all of the Syn HO-2 structures, several water molecules form a hydrogen-bond network at the distal hemepocket, which is involved in HO activity. Upon NO binding, the side-chain conformation of Tyr 156 changes. Tyr 156 is located at the hydrophobic cluster, which interrupts the possible H(+) pathway from the molecular surface to the hemepocket. Thus, Tyr 156 may function as a H(+) shuttle by changing conformation.

  13. Mechanisms of High Temperature Resistance of Synechocystis sp. PCC 6803: An Impact of Histidine Kinase 34

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    Jan Červený

    2015-03-01

    Full Text Available Synechocystis sp. PCC 6803 is a widely used model cyanobacterium for studying responses and acclimation to different abiotic stresses. Changes in transcriptome, proteome, lipidome, and photosynthesis in response to short term heat stress are well studied in this organism, and histidine kinase 34 (Hik34 is shown to play an important role in mediating such response. Corresponding data on long term responses, however, are fragmentary and vary depending on parameters of experiments and methods of data collection, and thus are hard to compare. In order to elucidate how the early stress responses help cells to sustain long-term heat stress, as well as the role of Hik34 in prolonged acclimation, we examined the resistance to long-term heat stress of wild-type and ΔHik34 mutant of Synechocystis. In this work, we were able to precisely control the long term experimental conditions by cultivating Synechocystis in automated photobioreactors, measuring selected physiological parameters within a time range of minutes. In addition, morphological and ultrastructural changes in cells were analyzed and western blotting of individual proteins was used to study the heat stress-affected protein expression. We have shown that the majority of wild type cell population was able to recover after 24 h of cultivation at 44 °C. In contrast, while ΔHik34 mutant cells were resistant to heat stress within its first hours, they could not recover after 24 h long high temperature treatment. We demonstrated that the early induction of HspA expression and maintenance of high amount of other HSPs throughout the heat incubation is critical for successful adaptation to long-term stress. In addition, it appears that histidine kinase Hik34 is an essential component for the long term high temperature resistance.

  14. NADPH-Thioredoxin Reductase C Mediates the Response to Oxidative Stress and Thermotolerance in the Cyanobacterium Anabaena sp PCC7120

    NARCIS (Netherlands)

    Sanchez-Riego, Ana M.; Mata-Cabana, Alejandro; Galmozzi, CarlaV.; Florencio, Francisco J.

    2016-01-01

    NADPH-thioredoxin reductase C (NTRC) is a bimodular enzyme composed of an NADPH-thioredoxin reductase and a thiioredoxin domain extension in the same protein. In plants, NTRC has been described to be involved in the protection of the chloroplast against oxidative stress damage through reduction of t

  15. FAD semiquinone stability regulates single- and two-electron reduction of quinones by Anabaena PCC7119 ferredoxin:NADP+ reductase and its Glu301Ala mutant.

    Science.gov (United States)

    Anusevicius, Zilvinas; Miseviciene, Lina; Medina, Milagros; Martinez-Julvez, Marta; Gomez-Moreno, Carlos; Cenas, Narimantas

    2005-05-15

    Flavoenzymes may reduce quinones in a single-electron, mixed single- and two-electron, and two-electron way. The mechanisms of two-electron reduction of quinones are insufficiently understood. To get an insight into the role of flavin semiquinone stability in the regulation of single- vs. two-electron reduction of quinones, we studied the reactions of wild type Anabaena ferredoxin:NADP(+)reductase (FNR) with 48% FAD semiquinone (FADH*) stabilized at the equilibrium (pH 7.0), and its Glu301Ala mutant (8% FADH* at the equilibrium). We found that Glu301Ala substitution does not change the quinone substrate specificity of FNR. However, it confers the mixed single- and two-electron mechanism of quinone reduction (50% single-electron flux), whereas the wild type FNR reduces quinones in a single-electron way. During the oxidation of fully reduced wild type FNR by tetramethyl-1,4-benzoquinone, the first electron transfer (formation of FADH*) is about 40 times faster than the second one (oxidation of FADH*). In contrast, the first and second electron transfer proceeded at similar rates in Glu301Ala FNR. Thus, the change in the quinone reduction mechanism may be explained by the relative increase in the rate of second electron transfer. This enabled us to propose the unified scheme of single-, two- and mixed single- and two-electron reduction of quinones by flavoenzymes with the central role of the stability of flavin/quinone ion-radical pair.

  16. Engineering limonene and bisabolene production in wild type and a glycogen-deficient mutant of Synechococcus sp. PCC 7002

    Energy Technology Data Exchange (ETDEWEB)

    Davies, Fiona K.; Work, Victoria H.; Beliaev, Alex S.; Posewitz, Matthew C.

    2014-06-19

    The plant terpenoids limonene (C10H16) and α-bisabolene (C15H24) are hydrocarbon precursors to a range of industrially-relevant chemicals. High-titer microbial synthesis of limonene and α- bisabolene could pave the way for advances in in vivo engineering of tailor-made hydrocarbons, and production at commercial scale. We have engineered the fast-growing unicellular euryhaline cyanobacterium Synechococcus sp. PCC 7002 to produce yields of 4 mg L-1 limonene and 0.6 mg L-1 α-bisabolene through heterologous expression of the Mentha spicata L-limonene synthase or the Abies grandis (E)-α-bisabolene synthase genes, respectively. Titers were significantly higher when a dodecane overlay was applied during culturing, suggesting either that dodecane traps large quantities of volatile limonene and α-bisabolene that would otherwise be lost to evaporation, and/or that continuous product removal in dodecane alleviates product feedback inhibition to promote higher rates of synthesis. We also investigate limonene and bisabolene production in the ΔglgC genetic background, where carbon partitioning is redirected at the expense of glycogen biosynthesis. The Synechococcus sp. PCC 7002 ΔglgC mutant excreted a suite of overflow metabolites (α-ketoisocaproate, pyruvate, α-ketoglutarate, succinate and acetate) during nitrogen deprivation, and also at the onset of stationary growth in nutrient-replete media. None of the excreted metabolites, however, appeared to be effectively utilized for terpenoid metabolism. Interestingly, we observed a 1.6 to 2.5-fold increase in the extracellular concentration of most excreted organic acids when the ΔglgC mutant was conferred with the ability to produce limonene. Overall, Synechococcus sp. PCC 7002 provides a highly promising platform for terpenoid biosynthetic and metabolic engineering efforts.

  17. Effect of mono- and dichromatic light quality on growth rates and photosynthetic performance of Synechococcus sp. PCC 7002

    Energy Technology Data Exchange (ETDEWEB)

    Bernstein, Hans C.; Konopka, Allan; Melnicki, Matthew R.; Hill, Eric A.; Kucek, Leo A.; Zhang, Shuyi; Shen, Gaozhong; Bryant, Donald A.; Beliaev, Alex S.

    2014-09-19

    Synechococcus sp. PCC 7002 was grown to steady state in optically thin turbidostat cultures under conditions for which light quantity and quality was systematically varied by modulating the output of narrow-band LEDs. Cells were provided photons absorbed primarily by chlorophyll (680 nm) or phycocyanin (630 nm) as the organism was subjected to four distinct mono- and dichromatic regimes. During cultivation with dichromatic light, growth rates displayed by Synechococcus sp. PCC 7002 were generally proportional to the total incident irradiance at values < 275 µmol photons m-2 s-1 and were not affected by the ratio of 630:680 nm wavelengths. Notably, under monochromatic light conditions, cultures exhibited similar growth rates only when they were irradiated with 630 nm light; cultures irradiated with only 680 nm light grew at rates that were 60 – 70% of those under other light quality regimes at equivalent irradiances. The functionality of photosystem II and associated processes such as maximum rate of photosynthetic electron transport, rate of cyclic electron flow, and rate of dark respiration generally increased as a function of growth rate. Nonetheless, some of the photophysiological parameters measured here displayed distinct patterns with respect to growth rate of cultures adapted to a single wavelength including phycobiliprotein content, which increased under severely light-limited growth conditions. Additionally, the ratio of photosystem II to photosystem I increased approximately 40% over the range of growth rates, although cells grown with 680 nm light only had the highest ratios. These results suggest the presence of effective mechanisms which allow acclimation of Synechococcus sp. PCC 7002 acclimation to different irradiance conditions.

  18. Effect of mono- and dichromatic light quality on growth rates and photosynthetic performance of Synechococcus sp. PCC 7002

    Directory of Open Access Journals (Sweden)

    Hans C Bernstein

    2014-09-01

    Full Text Available Synechococcus sp. PCC 7002 was grown to steady state in optically thin turbidostat cultures under conditions for which light quantity and quality was systematically varied by modulating the output of narrow-band LEDs. Cells were provided photons absorbed primarily by chlorophyll (680 nm or phycocyanin (630 nm as the organism was subjected to four distinct mono- and dichromatic regimes. During cultivation with dichromatic light, growth rates displayed by Synechococcus sp. PCC 7002 were generally proportional to the total incident irradiance at values < 275 µmol photons m-2 s-1 and were not affected by the ratio of 630:680 nm wavelengths. Notably, under monochromatic light conditions, cultures exhibited similar growth rates only when they were irradiated with 630 nm light; cultures irradiated with only 680 nm light grew at rates that were 60 – 70% of those under other light quality regimes at equivalent irradiances. The functionality of photosystem II and associated processes such as maximum rate of photosynthetic electron transport, rate of cyclic electron flow, and rate of dark respiration generally increased as a function of growth rate. Nonetheless, some of the photophysiological parameters measured here displayed distinct patterns with respect to growth rate of cultures adapted to a single wavelength including phycobiliprotein content, which increased under severely light-limited growth conditions. Additionally, the ratio of photosystem II to photosystem I increased approximately 40% over the range of growth rates, although cells grown with 680 nm light only had the highest ratios. These results suggest the presence of effective mechanisms which allow acclimation of Synechococcus sp. PCC 7002 acclimation to different irradiance conditions.

  19. Anabaena sp. mediated bio-oxidation of arsenite to arsenate in synthetic arsenic (III) solution: Process optimization by response surface methodology.

    Science.gov (United States)

    Jana, Animesh; Bhattacharya, Priyankari; Swarnakar, Snehasikta; Majumdar, Swachchha; Ghosh, Sourja

    2015-11-01

    Blue green algae Anabaena sp. was cultivated in synthetic arsenite solution to investigate its bio-oxidation potential for arsenic species. Response surface methodology (RSM) was employed based on a 3-level full factorial design considering four factors, viz. initial arsenic (III) concentration, algal dose, temperature and time. Bio-oxidation (%) of arsenic (III) was considered as response for the design. The study revealed that about 100% conversion of As (III) to As (V) was obtained for initial As (III) concentration of 2.5-7.5 mg/L at 30 °C for 72 h of exposure using 3 g/L of algal dose signifying a unique bio-oxidation potential of Anabaena sp. The dissolved CO2 (DCO2) and oxygen (DO) concentration in solution was monitored during the process and based on the data, a probable mechanism was proposed wherein algal cell acts like a catalytic membrane surface and expedites the bio-oxidation process. Bioaccumulation of arsenic, as well as, surface adsorption on algal cell was found considerably low. Lipid content of algal biomass grown in arsenite solution was found slightly lower than that of algae grown in synthetic media. Toxicity effects on algal cells due to arsenic exposure were evaluated in terms of comet assay and chlorophyll a content which indicated DNA damage to some extent along with very little decrease in chlorophyll a content. In summary, the present study explored the potential application of Anabaena sp. as an ecofriendly and sustainable option for detoxification of arsenic contaminated natural water with value-added product generation.

  20. Diurnal Regulation of Cellular Processes in the Cyanobacterium Synechocystis sp. Strain PCC 6803: Insights from Transcriptomic, Fluxomic, and Physiological Analyses

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    Rajib Saha

    2016-05-01

    Full Text Available Synechocystis sp. strain PCC 6803 is the most widely studied model cyanobacterium, with a well-developed omics level knowledgebase. Like the lifestyles of other cyanobacteria, that of Synechocystis PCC 6803 is tuned to diurnal changes in light intensity. In this study, we analyzed the expression patterns of all of the genes of this cyanobacterium over two consecutive diurnal periods. Using stringent criteria, we determined that the transcript levels of nearly 40% of the genes in Synechocystis PCC 6803 show robust diurnal oscillating behavior, with a majority of the transcripts being upregulated during the early light period. Such transcripts corresponded to a wide array of cellular processes, such as light harvesting, photosynthetic light and dark reactions, and central carbon metabolism. In contrast, transcripts of membrane transporters for transition metals involved in the photosynthetic electron transport chain (e.g., iron, manganese, and copper were significantly upregulated during the late dark period. Thus, the pattern of global gene expression led to the development of two distinct transcriptional networks of coregulated oscillatory genes. These networks help describe how Synechocystis PCC 6803 regulates its metabolism toward the end of the dark period in anticipation of efficient photosynthesis during the early light period. Furthermore, in silico flux prediction of important cellular processes and experimental measurements of cellular ATP, NADP(H, and glycogen levels showed how this diurnal behavior influences its metabolic characteristics. In particular, NADPH/NADP+ showed a strong correlation with the majority of the genes whose expression peaks in the light. We conclude that this ratio is a key endogenous determinant of the diurnal behavior of this cyanobacterium.

  1. Characterization of a sodium-regulated glutaminase from cyanobacterium Synechocystis sp. PCC 6803

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Glutaminase is widely distributed among microorganisms and mammals with important functions. Lit-tle is known regarding the biochemical properties and functions of the deamidating enzyme glutami-nase in cyanobacteria. In this study a putative glutaminase encoded by gene slr2079 in Synechocystis sp. PCC 6803 was investigated. The slr2079 was expressed as histidine-tagged fusion protein in Es-cherichia coli. The purified protein possessed glutaminase activity, validating the functional assign-ment of the genomic annotation. The apparent Km value of the recombinant protein for glutamine was 26.6 ± 0.9 mmol/L, which was comparable to that for some of other microbial glutaminases. Analysis of the purified protein revealed a two-fold increase in catalytic activity in the presence of 1 mol/L Na+. Moreover, the Km value was decreased to 12.2 ± 1.9 mmol/L in the presence of Na+. These data demon-strate that the recombinant protein Slr2079 is a glutaminase which is regulated by Na+ through in-creasing its affinity for substrate glutamine. The slr2079 gene was successfully disrupted in Synecho-cystis by targeted mutagenesis and the △slr2079 mutant strain was analyzed. No differences in cell growth and oxygen evolution rate were observed between △slr2079 and the wild type under standard growth conditions, demonstrating slr2079 is not essential in Synechocystis. Under high salt stress condition, however, △slr2079 cells grew 1.25-fold faster than wild-type cells. Moreover, the photosyn-thetic oxygen evolution rate of △slr2079 cells was higher than that of the wild-type. To further charac-terize this phenotype, a number of salt stress-related genes were analyzed by semi-quantitative RT-PCR. Expression of gdhB and prc was enhanced and expression of desD and guaA was repressed in △slr2079 compared to the wild type. In addition, expression of two key enzymes of ammonium assimi-lation in cyanobacteria, glutamine synthetase (GS) and glutamate synthase (GOGAT) was examined

  2. Characterization of a sodium-regulated glutaminase from cyanobacterium Synechocystis sp. PCC 6803

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jie; ZHOU JunXia; YANG HaoMeng; YAN ChengShi; HUANG Fang

    2008-01-01

    Glutaminase is widely distributed among microorganisms and mammals with important funotions. Little is known regarding the biochemical properties and functions of the deamidating enzyme glutaminase in cyanobacteria. In this study a putative glutaminase encoded by gene slr2079 in Synechocystis sp. PCC 6803 was investigated. The slr2079 was expressed as histidine-tagged fusion protein in Escheriohia coli. The purified protein possessed glutaminase activity, validating the functional assignment of the genomic annotation. The apparent Km value of the recombinant protein for glutamine was 26.6 ± 0.9 mmol/L, which was comparable to that for some of other microbial glutaminases. Analysis of the purified protein revealed a two-fold increase in catalytic activity in the presence of 1 mol/L Na+. Moreover, the Km value was decreased to 12.2 ± 1.9 mmol/L in the presence of Na+. These data demonstrate that the recombinant protein Slr2079 is a glutaminase which is regulated by Na+ through inoreasing its affinity for substrate glutamine. The sir2079 gene was successfully disrupted in Synechocystis by targeted mutagenesis and the △slr2079 mutant strain was analyzed. No differences in cell growth and oxygen evolution rate were observed between △slr2079 and the wild type under standard growth conditions, demonstrating sir2079 is not essential in Synechocystis. Under high salt stress condition, however, △slr2079 cells grew 1.25-fold faster than wild- type cells. Moreover, the photosynthetic oxygen evolution rate of △slr2079 cells was higher than that of the wild-type. To further characterize this phenotype, a number of salt stress-related genes were analyzed by semi-quantitative RT-PCR. Expression of gdhB and prc was enhanced and expression of desD and guaA was repressed in △slr2079 compared to the wild type. In addition, expression of two key enzymes of ammonium assimilation in cyanobacteria, glutamine synthetase (GS) and glutamate synthase (GOGAT) was examined by semi

  3. Temperature dependence and polarization of fluorescence from Photosystem I in the cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Wittmershaus, B P; Woolf, V M; Vermaas, W F

    1992-02-01

    To determine the fluorescence properties of cyanobacterial Photosystem I (PS I) in relatively intact systems, fluorescence emission from 20 to 295 K and polarization at 77 K have been measured from phycobilisomes-less thylakoids of Synechocystis sp. PCC 6803 and a mutant strain lacking Photosystem II (PS II). At 295 K, the fluorescence maxima are 686 nm in the wild type from PS I and PS II and at 688 nm from PS I in the mutant. This emission is characteristic of bulk antenna chlorophylls (Chls). The 690-nm fluorescence component of PS I is temperature independent. For wild-type and mutant, 725-nm fluorescence increases by a factor of at least 40 from 295 to 20 K. We model this temperature dependence assuming a small number of Chls within PS I, emitting at 725 nm, with an energy level below that of the reaction center, P700. Their excitation transfer rate to P700 decreases with decreasing temperature increasing the yield of 725-nm fluorescence.Fluorescence excitation spectra of polarized emission from low-energy Chls were measured at 77 and 295 K on the mutant lacking PS II. At excitation wavelengths longer than 715 nm, 760-nm emission is highly polarized indicating either direct excitation of the emitting Chls with no participation in excitation transfer or total alignment of the chromophores. Fluorescence at 760 nm is unpolarized for excitation wavelengths shorter than 690 nm, inferring excitation transfer between Chls before 760-nm fluorescence occurs.Our measurements illustrate that: 1) a single group of low-energy Chls (F725) of the core-like PS I complex in cyanobacteria shows a strongly temperature-dependent fluorescence and, when directly excited, nearly complete fluorescence polarization, 2) these properties are not the result of detergent-induced artifacts as we are examining intact PS I within the thylakoid membrane of S. 6803, and 3) the activation energy for excitation transfer from F725 Chls to P700 is less than that of F735 Chls in green plants; F725

  4. Involvement of sulfoquinovosyl diacylglycerol in DNA synthesis in Synechocystis sp. PCC 6803

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    Aoki Motohide

    2012-02-01

    Full Text Available Abstract Background Sulfoquinovosyl diacylglycerol (SQDG is present in the membranes of cyanobacteria and their postulated progeny, plastids, in plants. A cyanobacterium, Synechocystis sp. PCC 6803, requires SQDG for growth: its mutant (SD1 with the sqdB gene for SQDG synthesis disrupted can grow with external supplementation of SQDG. However, upon removal of SQDG from the medium, its growth is retarded, with a decrease in the cellular content of SQDG throughout cell division, and finally ceases. Concomitantly with the decrease in SQDG, the maximal activity of photosynthesis at high-light intensity is repressed by 40%. Findings We investigated effects of SQDG-defect on physiological aspects in Synechocystis with the use of SD1. SD1 cells defective in SQDG exhibited normal photosynthesis at low-light intensity as on culturing. Meanwhile, SD1 cells defective in SQDG were impaired in light-activated heterotrophic growth as well as in photoautotrophic growth. Flow cytometric analysis of the photoautotrophically growing cells gave similar cell size histograms for the wild type and SD1 supplemented with SQDG. However, the profile of SD1 defective in SQDG changed such that large part of the cell population was increased in size. Of particular interest was the microscopic observation that the mitotic index, i.e., population of dumbbell-like cells with a septum, increased from 14 to 29% in the SD1 culture without SQDG. Flow cytometric analysis also showed that the enlarged cells of SD1 defective in SQDG contained high levels of Chl, however, the DNA content was low. Conclusions Our experiments strongly support the idea that photosynthesis is not the limiting factor for the growth of SD1 defective in SQDG, and that SQDG is responsible for some physiologically fundamental process common to both photoautotrophic and light-activated heterotrophic growth. Our findings suggest that the SQDG-defect allows construction of the photosynthetic machinery at an

  5. Glutaredoxins are essential for stress adaptation in the cyanobacterium Synechocystis sp. PCC 6803.

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    Ana M Sánchez-Riego

    2013-11-01

    Full Text Available Glutaredoxin are small redox proteins able to reduce disulfides and mixed disulfides between GSH and proteins. Synechocystis sp. PCC 6803 contains three genes coding for glutaredoxins: ssr2061 (grxA and slr1562 (grxB code for dithiolic glutaredoxins while slr1846 (grxC codes for a monothiolic glutaredoxin. We have analyzed the expression of these glutaredoxins in response to different stresses, such as high light, H2O2 and heat shock. Analysis of the mRNA levels showed that grxA is only induced by heat while grxC is repressed by heat shock and is induced by high light and H2O2. In contrast, grxB expression was maintained almost constant under all conditions. Analysis of GrxA and GrxC protein levels by western blot showed that GrxA increases in response to high light, heat or H2O2 while GrxC is only induced by high light and H2O2, in accordance with its mRNA levels. In addition, we have also generated mutants that have interrupted one, two or three glutaredoxin genes. These mutants were viable and did not show any different phenotype from the WT under standard growth conditions. Nevertheless, analysis of these mutants under several stress conditions revealed that single grxA mutants grow slower after H2O2, heat and high light treatments, while mutants in grxB are indistinguishable from WT. grxC mutants were hypersensitive to treatments with H2O2, heat, high light and metals. A double grxAgrxC mutant was found to be even more sensitive to H2O2 than each corresponding single mutants. Surprisingly a mutation in grxB suppressed totally or partially the phenotypes of grxA and grxC mutants except the H2O2 sensitivity of the grxC mutant. This suggests that grxA and grxC participate in independent pathways while grxA and grxB participate in a common pathway for H2O2 resistance. The data presented here show that glutaredoxins are essential for stress adaptation in cyanobacteria, although their targets and mechanism of action remain unidentified.

  6. Cadmium toxicity in diazotrophic Anabaena spp. adjudged by hasty up-accumulation of transporter and signaling and severe down-accumulation of nitrogen metabolism proteins.

    Science.gov (United States)

    Singh, Prashant Kumar; Shrivastava, Alok Kumar; Chatterjee, Antra; Pandey, Sarita; Rai, Snigdha; Singh, Shilpi; Rai, L C

    2015-09-01

    Present study demonstrates interspecies variation in proteome and survival strategy of three Anabaena species i.e., Anabaena L31, Anabaena sp. PCC 7120 and Anabaena doliolum subjected to respective LC50 doses of Cd at 0, 1, 3, 5 and 7day intervals. The proteome coverage with 452 differentially accumulated proteins unveiled species and time specific expression and interaction network of proteins involved in important cellular functions. Statistical analysis of protein abundance across Cd-treated proteomes clustered their co-expression pattern into four groups viz., (i) early (days 1 and 3) accumulated proteins, (ii) proteins up-accumulated for longer duration, (iii) late (days 5 and 7) accumulated proteins, and (iv) mostly down-accumulated proteins. Appreciable growth of Cd treated A L31 over other two species may be ascribed to proteins contained in the first and second groups (belonging to energy and carbohydrate metabolism (TK, G6-PI, PGD, FBA, PPA, ATP synthase)), sulfur metabolism (GR, GST, PGDH, PAPS reductase, GDC-P, and SAM synthetase), fatty acid metabolism (AspD, PspA, SQD-1), phosphorous metabolism (PhoD, PstB and SQD1), molecular chaperones (Gro-EL, FKBP-type peptidylprolyl isomerase), and antioxidative defense enzymes (SOD-A, catalase). Anabaena sp. PCC 7120 harboring proteins largely from the third group qualified as a late accumulator and A. doliolum housing majority of proteins from the fourth group emerged as the most sensitive species. Thus early up-accumulation of transporter and signaling category proteins and drastic reduction of nitrogen assimilation proteins could be taken as a vital indicator of cadmium toxicity in Anabaena spp. This article is part of a Special Issue entitled: Proteomics in India.

  7. Functional analysis of the PsbX protein by deletion of the corresponding gene in Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Funk, C

    2000-12-01

    The psbX gene (sml0002) coding for a 4.1 kDa protein in Photosystem II of plants and cyanobacteria was deleted in both wild type and in a Photosystem I-less mutant of the cyanobacterium Synechocystis sp. PCC 6803. Polymerase chain reaction and sequencing analysis showed that the mutants had completely segregated. Deletion of the PsbX protein does not seem to influence growth rate, electron transport or water oxidation ability. Whereas a high light induction of the psbX mRNA could be observed in wild type, deletion of the gene did not lead to high light sensibility. Light saturation measurements and 77K fluorescence measurements indicated a minor disconnection of the antenna in the deletion mutant. Furthermore, fluorescence induction measurements as well as immuno-staining of the D1 protein showed that the amount of Photosystem II complexes in the mutants was reduced by 30%. Therefore, PsbX does not seem to be necessary for the Photosystem II electron transport, but directly or indirectly involved in the regulation of the amount of functionally active Photosystem II centres in Synechocystis sp. PCC 6803.

  8. Homology modeling, docking studies and functional analysis of various azoreductase accessory interacting proteins of Nostoc sp.PCC7120.

    Science.gov (United States)

    Philem, Priyadarshini Devi; Adhikari, Samrat

    2012-01-01

    Azo dyes have become a threat to public health because of its toxicity and carcinogenicity. Azoreductase enzyme plays a pivotal role in the degradation of azodyes released by industrial effluents and other resources. The degradation pathway has to be studied in detail for increasing the activity of azoreductase and for better degradation of azo dyes. But the data available on cyanobacterial azoreductase enzyme and its degradation pathway are still very less. Therefore the present work explored the azoreductase pathway of the cyanobacterium Nostoc sp. PCC7120 for better understanding of the degradation pathway and the other accessory interacting proteins involved. The accessory interacting proteins of azoreductase from cyanobacterium Nostoc sp. PCC7120 were obtained from STRING database. The proteins do not have a comprehensive three dimensional structure and are hypothetical. The secondary structure and functional analysis indicated that the proteins are all soluble proteins, without disulphide bonds and have alpha helices only. The structural prediction and docking study showed that alr2106, alr1063 and alr2326 have best docking result which tally with the STRING database confidence score and thus these proteins could possibly enhance the azoreductase activity and better dye degradation. These results will pave way for further increase in azoreductase activity and for better understanding of the dye degradation pathway.

  9. Localization of Membrane Proteins in the Cyanobacterium Synechococcus sp. PCC7942 (Radial Asymmetry in the Photosynthetic Complexes).

    Science.gov (United States)

    Sherman, D. M.; Troyan, T. A.; Sherman, L. A.

    1994-09-01

    Localization of membrane proteins in the cyanobacterium Synechococcus sp. PCC7942 was determined by transmission electron microscopy utilizing immunocytochemistry with cells prepared by freeze-substitution. This preparation procedure maintained cellular morphology and permitted detection of cellular antigens with high sensitivity and low background. Synechococcus sp. PCC7942 is a unicellular cyanobacterium with thylakoids organized in concentric layers toward the periphery of the cell. Cytochrome oxidase was localized almost entirely in the cytoplasmic membrane, whereas a carotenoprotein (P35) was shown to be a cell wall component. The major photosystem II (PSII) proteins (D1, D2 CP43, and CP47) were localized throughout the thylakoids. Proteins of the Cyt b6/f complex were found to have a similar distribution. Thylakoid luminal proteins, such as the Mn-stabilizing protein, were located primarily in the thylakoid, but a small, reproducible fraction was found in the outer compartment. The photosystem I (PSI) reaction center proteins and the ATP synthase proteins were found associated mostly with the outermost thylakoid and with the cytoplasmic membrane. These results indicated that the photosynthetic apparatus is not evenly distributed throughout the thylakoids. Rather, there is a radial asymmetry such that much of the PSI and the ATPase synthase is located in the outermost thylakoid. The relationship of this structure to the photosynthetic mechanism is discussed. It is suggested that the photosystems are separated because of kinetic differences between PSII and PSI, as hypothesized by H.-W. Trissl and C. Wilhelm (Trends Biochem Sci [1993] 18:415-419).

  10. MapA, an iron-regulated, cytoplasmic membrane protein in the cyanobacterium Synechococcus sp. strain PCC7942.

    Science.gov (United States)

    Webb, R; Troyan, T; Sherman, D; Sherman, L A

    1994-08-01

    Growth of Synechococcus sp. strain PCC 7942 in iron-deficient media leads to the accumulation of an approximately 34-kDa protein. The gene encoding this protein, mapA (membrane-associated protein A), has been cloned and sequenced (GenBank accession number, L01621). The mapA transcript is not detectable in normally grown cultures but is stably accumulated by cells grown in iron-deficient media. However, the promoter sequence for this gene does not resemble other bacterial iron-regulated promoters described to date. The carboxyl-terminal region of the derived amino acid sequence of MapA resembles bacterial proteins involved in iron acquisition, whereas the amino-terminal end of MapA has a high degree of amino acid identity with the abundant, chloroplast envelope protein E37. An approach employing improved cellular fractionation techniques as well as electron microscopy and immunocytochemistry was essential in localizing MapA protein to the cytoplasmic membrane of Synechococcus sp. strain PCC 7942. When these cells were grown under iron-deficient conditions, a significant fraction of MapA could also be localized to the thylakoid membranes.

  11. The gamma-aminobutyric acid shunt contributes to closing the tricarboxylic acid cycle in Synechocystis sp PCC 6803

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, W; Brune, D; Vermaas, WFJ

    2014-07-16

    A traditional 2-oxoglutarate dehydrogenase complex is missing in the cyanobacterial tricarboxylic acid cycle. To determine pathways that convert 2-oxoglutarate into succinate in the cyanobacterium Synechocystis sp. PCC 6803, a series of mutant strains, Delta sll1981, Delta slr0370, Delta slr1022 and combinations thereof, deficient in 2-oxoglutarate decarboxylase (Sll1981), succinate semialdehyde dehydrogenase (Slr0370), and/or in gamma-aminobutyrate metabolism (Slr1022) were constructed. Like in Pseudomonas aeruginosa, N-acetylornithine aminotransferase, encoded by slr1022, was shown to also function as gamma-aminobutyrate aminotransferase, catalysing gamma-aminobutyrate conversion to succinic semialdehyde. As succinic semialdehyde dehydrogenase converts succinic semialdehyde to succinate, an intact gamma-aminobutyrate shunt is present in Synechocystis. The Delta sll1981 strain, lacking 2-oxoglutarate decarboxylase, exhibited a succinate level that was 60% of that in wild type. However, the succinate level in the Delta slr1022 and Delta slr0370 strains and the Delta sll1981/Delta slr1022 and Delta sll1981/Delta slr0370 double mutants was reduced to 20-40% of that in wild type, suggesting that the gamma-aminobutyrate shunt has a larger impact on metabolite flux to succinate than the pathway via 2-oxoglutarate decarboxylase. C-13-stable isotope analysis indicated that the gamma-aminobutyrate shunt catalysed conversion of glutamate to succinate. Independent of the 2-oxoglutarate decarboxylase bypass, the gamma-aminobutyrate shunt is a major contributor to flux from 2-oxoglutarate and glutamate to succinate in Synechocystis sp. PCC 6803.

  12. A gene (ccmA) required for carboxysome formation in the cyanobacterium Synechocystis sp. strain PCC6803.

    Science.gov (United States)

    Ogawa, T; Marco, E; Orus, M I

    1994-04-01

    A high-CO2-requiring mutant, G7, of Synechocystis sp. strain PCC6803 capable of inorganic carbon transport but unable to utilize the intracellular inorganic carbon pool for photosynthesis was isolated. Transmission electron micrographs of the mutant indicated that the mutant does not have any carboxysomes. A clone (pHPG7) with a 7.5-kbp DNA insert that transforms the G7 mutant to the wild-type phenotype was isolated from a genomic library of wild-type Synechocystis sp. strain PCC6803. Complementation tests with subclones identified the mutation site in G7 within 208 bp. Sequencing of nucleotides in this region elucidated an open reading frame, designated ccmA, encoding a protein of 302 amino acids. Cloning and sequence analysis of the respective G7 gene revealed an A-to-G substitution that results in an Asp-to-Gly substitution in the deduced amino acid. The result indicated that the ccmA gene encodes a protein essential for the formation of carboxysomes. An open reading frame encoding a proline-rich protein of 271 amino acids was found downstream of the ccmA gene, but no ccm-like genes or rbc operon was found in this region.

  13. Role of manganese in protection against oxidative stress under iron starvation in cyanobacterium Anabaena 7120.

    Science.gov (United States)

    Kaushik, Manish Singh; Srivastava, Meenakshi; Verma, Ekta; Mishra, Arun Kumar

    2015-06-01

    The cyanobacterium Anabaena sp. PCC 7120 was grown in presence and absence of iron to decipher the role of manganese in protection against the oxidative stress under iron starvation and growth, manganese uptake kinetics, antioxidative enzymes, lipid peroxidation, electrolyte leakage, thiol content, total peroxide, proline and NADH content was investigated. Manganese supported the growth of cyanobacterium Anabaena 7120 under iron deprived conditions where maximum uptake rate of manganese was observed with lower K(m) and higher V(max) values. Antioxidative enzymes were also found to be elevated in iron-starved conditions. Estimation of lipid peroxidation and electrolyte leakage depicted the role of manganese in stabilizing the integrity of the membrane which was considered as the prime target of oxygen free radicals in oxidative stress. The levels of total peroxide, thiol, proline and NADH content, which are the representative of oxidative stress response in Anabaena 7120, were also showed increasing trends in iron starvation. Hence, the results discerned, clearly suggested the role of manganese in protection against the oxidative stress in cyanobacterium Anabaena 7120 under iron starvation either due to its antioxidative properties or involvement as cofactor in a number of antioxidative enzymes.

  14. Improved protein overexpression and purification strategies for structural studies of cyanobacterial metal-responsive transcription factor, SmtB from marine Synechococcus sp. PCC 7002.

    Science.gov (United States)

    Mahadev, Shelake Rahul; Hayashi, Hidenori; Ikegami, Takahisa; Abe, Shunnosuke; Morita, Eugene Hayato

    2013-12-01

    There are structural and functional differences in SmtB homologs, metal-responsive transcription factors responsible for sensing of excess heavy metal ions in marine and freshwater cyanobacterial strains. The structure of SmtB from freshwater Synechococcus sp. strain PCC 7942 is elucidated with nuclear magnetic resonance (NMR) and crystallography techniques. But knowledge about the functioning of SmtB homologs from marine species is limited till date. To enable NMR spectroscopic studies for investigating structural and functional aspects, modified protocols with higher yields of isotopically labeled SmtB, from marine species like Synechococcus sp. PCC 7002 are essential. In this study, smtB gene was cloned from genome of Synechococcus sp. PCC 7002 and overexpression protocol for recombinant SmtB was standardized in Escherichia coli containing T7 RNA polymerase/promoter system. Further, the protocol for large-scale production, isotope labeling with (15)N, and purification of recombinant SmtB in E. coli BL21(DE3)/pLysS cells was developed. Purified recombinant protein was successfully used for NMR spectroscopy experiments. These results indicate that the overexpression technique now developed is applicable to the structural and functional studies for the proteins being homologous to cyanobacterial SmtB from Synechococcus sp. PCC 7002.

  15. Inactivation of ccmO in Synechococcus sp. Strain PCC 7942 Results in a Mutant Requiring High Levels of CO(2).

    Science.gov (United States)

    Marco, E; Martinez, I; Ronen-Tarazi, M; Orus, M I; Kaplan, A

    1994-03-01

    Inactivation of ccmO in Synechococcus sp. strain PCC 7942 resulted in a mutant which possesses aberrant carboxysomes and a normal inorganic carbon uptake capability but a reduced ability to photosynthetically utilize the internal inorganic carbon pool. Consequently, it exhibits low apparent photosynthetic affinity for extracellular inorganic carbon and demands high levels of CO(2) for growth.

  16. Slr1670 from Synechocystis sp. PCC 6803 is required for the re-assimilation of the osmolyte glucosylglycerol

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    Philipp Savakis

    2016-08-01

    Full Text Available When subjected to mild salt stress, the cyanobacterium Synechocystis sp. PCC 6803 produces small amounts of glycerol through an as of yet unidentified pathway. Here, we show that this glycerol is a degradation product of the main osmolyte of this organism, glucosylglycerol (GG. Inactivation of ggpS, encoding the first step of GG-synthesis, abolished de novo synthesis of glycerol, while the ability to hydrolyze exogenously supplied glucoslylglycerol was unimpaired. Inactivation of glpK, encoding glycerol kinase, had no effect on glycerol synthesis. Inactivation of slr1670, encoding a GHL5-type putative glycoside hydrolase, abolished de novo synthesis of glycerol, as well as hydrolysis of GG, and led to increased intracellular concentrations of this osmolyte. Slr1670 therefore presumably displays GG hydrolase activity. A gene homologous to the one encoded by slr1670 occurs in a wide range of cyanobacteria, proteobacteria and archaea. In cyanobacteria, it co-occurs with genes involved in GG-synthesis.

  17. Metabolic model of Synechococcus sp. PCC 7002: Prediction of flux distribution and network modification for enhanced biofuel production.

    Science.gov (United States)

    Hendry, John I; Prasannan, Charulata B; Joshi, Aditi; Dasgupta, Santanu; Wangikar, Pramod P

    2016-08-01

    Flux Balance Analysis was performed with the Genome Scale Metabolic Model of a fast growing cyanobacterium Synechococcus sp. PCC 7002 to gain insights that would help in engineering the organism as a production host. Gene essentiality and synthetic lethality analysis revealed a reduced metabolic robustness under genetic perturbation compared to the heterotrophic bacteria Escherichia coli. Under glycerol heterotrophy the reducing equivalents were generated from tricarboxylic acid cycle rather than the oxidative pentose phosphate pathway. During mixotrophic growth in glycerol the photosynthetic electron transport chain was predominantly used for ATP synthesis with a photosystem I/photosystem II flux ratio higher than that observed under autotrophy. An exhaustive analysis of all possible double reaction knock outs was performed to reroute fixed carbon towards ethanol and butanol production. It was predicted that only ∼10% of fixed carbon could be diverted for ethanol and butanol production.

  18. Increased bioplastic production with an RNA polymerase sigma factor SigE during nitrogen starvation in Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Osanai, Takashi; Numata, Keiji; Oikawa, Akira; Kuwahara, Ayuko; Iijima, Hiroko; Doi, Yoshiharu; Tanaka, Kan; Saito, Kazuki; Hirai, Masami Yokota

    2013-12-01

    Because cyanobacteria directly harvest CO2 and light energy, their carbon metabolism is important for both basic and applied sciences. Here, we show that overexpression of the sigma factor sigE in Synechocystis sp. PCC 6803 widely changes sugar catabolism and increases production of the biodegradable polyester polyhydroxybutyrate (PHB) during nitrogen starvation. sigE overexpression elevates the levels of proteins implicated in glycogen catabolism, the oxidative pentose phosphate pathway, and polyhydroxyalkanoate biosynthesis. PHB accumulation is enhanced by sigE overexpression under nitrogen-limited conditions, yet the molecular weights of PHBs synthesized by the parental glucose-tolerant and sigE overexpression strain are similar. Although gene expression induced by nitrogen starvation is changed and other metabolites (such as GDP-mannose and citrate) accumulate under sigE overexpression, genetic engineering of this sigma factor altered the metabolic pathway from glycogen to PHB during nitrogen starvation.

  19. The role of Slr0151, a tetratricopeptide repeat protein from Synechocystis sp. PCC 6803, during Photosystem II assembly and repair

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    Anna eRast

    2016-05-01

    Full Text Available The assembly and repair of photosystem II (PSII is facilitated by a variety of assembly factors. Among those, the tetratricopeptide repeat (TPR protein Slr0151 from Synechocystis sp. PCC 6803 (hereafter Synechocystis has previously been assigned a repair function under high light conditions (Yang et al., 2014, J. Integr. Plant Biol. 56, 1136-50. Here, we show that inactivation of Slr0151 affects thylakoid membrane ultrastructure even under normal light conditions. Moreover, the level and localization of Slr0151 are affected in a variety of PSII-related mutants. In particular, the data suggest a close functional relationship between Slr0151 and Sll0933, which interacts with Ycf48 during PSII assembly and is homologous to PAM68 in Arabidopsis thaliana. Immunofluorescence analysis revealed a punctate distribution of Slr0151 within several different membrane types in Synechocystis cells.

  20. Complementation of a phycocyanin-bilin lyase from Synechocystis sp. PCC 6803 with a nucleomorph-encoded open reading frame from the cryptophyte Guillardia theta

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    Nyalwidhe Julius

    2008-05-01

    Full Text Available Abstract Background Cryptophytes are highly compartmentalized organisms, expressing a secondary minimized eukaryotic genome in the nucleomorph and its surrounding remnant cytoplasm, in addition to the cell nucleus, the mitochondrion and the plastid. Because the members of the nucleomorph-encoded proteome may contribute to essential cellular pathways, elucidating nucleomorph-encoded functions is of utmost interest. Unfortunately, cryptophytes are inaccessible for genetic transformations thus far. Therefore the functions of nucleomorph-encoded proteins must be elucidated indirectly by application of methods in genetically accessible organisms. Results Orf222, one of the uncharacterized nucleomorph-specific open reading frames of the cryptophyte Guillardia theta, shows homology to slr1649 of Synechocystis sp. PCC 6803. Recently a further homolog from Synechococcus sp. PCC 7002 was characterized to encode a phycocyanin-β155-bilin lyase. Here we show by insertion mutagenesis that the Synechocystis sp. PCC 6803 slr1649-encoded protein also acts as a bilin lyase, and additionally contributes to linker attachment and/or stability of phycobilisomes. Finally, our results indicate that the phycocyanin-β155-bilin lyase of Synechocystis sp. PCC 6803 can be complemented in vivo by the nucleomorph-encoded open reading frame orf222. Conclusion Our data show that the loss of phycocyanin-lyase function causes pleiotropic effects in Synechocystis sp. PCC 6803 and indicate that after separating from a common ancestor protein, the phycoerythrin lyase from Guillardia theta has retained its capacity to couple a bilin group to other phycobiliproteins. This is a further, unexpected example of the universality of phycobiliprotein lyases.

  1. Effect of mono- and dichromatic light quality on growth rates and photosynthetic performance of Synechococcus sp. PCC 7002.

    Science.gov (United States)

    Bernstein, Hans C; Konopka, Allan; Melnicki, Matthew R; Hill, Eric A; Kucek, Leo A; Zhang, Shuyi; Shen, Gaozhong; Bryant, Donald A; Beliaev, Alexander S

    2014-01-01

    Synechococcus sp. PCC 7002 was grown to steady state in optically thin turbidostat cultures under conditions for which light quantity and quality was systematically varied by modulating the output of narrow-band LEDs. Cells were provided photons absorbed primarily by chlorophyll (680 nm) or phycocyanin (630 nm) as the organism was subjected to four distinct mono- and dichromatic regimes. During cultivation with dichromatic light, growth rates were generally proportional to the total incident irradiance at values <275 μmol photons m(-2) · s(-1) and were not affected by the ratio of 630:680 nm wavelengths. Notably, under monochromatic light conditions, cultures exhibited similar growth rates only when they were irradiated with 630 nm light; cultures irradiated with only 680 nm light grew at rates that were 60-70% of those under other light quality regimes at equivalent irradiances. The functionality of photosystem II and associated processes such as maximum rate of photosynthetic electron transport, rate of cyclic electron flow, and rate of dark respiration generally increased as a function of growth rate. Nonetheless, some of the photophysiological parameters measured here displayed distinct patterns with respect to growth rate of cultures adapted to a single wavelength including phycobiliprotein content, which increased under severely light-limited growth conditions. Additionally, the ratio of photosystem II to photosystem I increased ~40% over the range of growth rates, although cells grown with 680 nm light only had the highest ratios. These results suggest the presence of effective mechanisms which allow acclimation of Synechococcus sp. PCC 7002 acclimation to different irradiance conditions.

  2. Utilization of Anabaena sp. in CO{sub 2} removal processes. Modelling of biomass, exopolysaccharides productivities and CO{sub 2} fixation rate

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Fernandez, J.F.; Gonzalez-Lopez, C.V.; Acien Fernandez, F.G.; Fernandez Sevilla, J.M.; Molina Grima, E. [Almeria Univ. (Spain). Dept. of Chemical Engineering

    2012-05-15

    This paper focuses on modelling the growth rate and exopolysaccharides production of Anabaena sp. ATCC 33047, to be used in carbon dioxide removal and biofuels production. For this, the influence of dilution rate, irradiance and aeration rate on the biomass and exopolysaccharides productivity, as well as on the CO{sub 2} fixation rate, have been studied. The productivity of the cultures was maximum at the highest irradiance and dilution rate assayed, resulting to 0.5 g{sub bio} l{sup -1} day{sup -1} and 0.2 g{sub eps} l{sup -1} day{sup -1}, and the CO{sub 2} fixation rate measured was 1.0 gCO{sub 2} l{sup -1} day{sup -1}. The results showed that although Anabaena sp. was partially photo-inhibited at irradiances higher than 1,300 {mu}E m-2 s{sup -1}, its growth rate increases hyperbolically with the average irradiance inside the culture, and so does the specific exopolysaccharides production rate. The latter, on the other hand, decreases under high external irradiances, indicating that the exopolysaccharides metabolism hindered by photo-damage. Mathematical models that consider these phenomena have been proposed. Regarding aeration, the yield of the cultures decreased at rates over 0.5 v/v/min or when shear rates were higher than 60 s{sup -1}, demonstrating the existence of thus existence of stress damage by aeration. The behaviour of the cultures has been verified outdoors in a pilot-scale airlift tubular photobioreactor. From this study it is concluded that Anabaena sp. is highly recommended to transform CO{sub 2} into valuable products as has been proved capable of metabolizing carbon dioxide at rates of 1.2 gCO{sub 2} l{sup -1} day{sup -1} outdoors. The adequacy of the proposed equations is demonstrated, resulting to a useful tool in the design and operation of photobioreactors using this strain. (orig.)

  3. Quantitative proteomics reveals dynamic responses of Synechocystis sp. PCC 6803 to next-generation biofuel butanol.

    Science.gov (United States)

    Tian, Xiaoxu; Chen, Lei; Wang, Jiangxin; Qiao, Jianjun; Zhang, Weiwen

    2013-01-14

    Butanol is a promising biofuel, and recent metabolic engineering efforts have demonstrated the use of photosynthetic cyanobacterial hosts for its production. However, cyanobacteria have very low tolerance to butanol, limiting the economic viability of butanol production from these renewable producing systems. The existing knowledge of molecular mechanism involved in butanol tolerance in cyanobacteria is very limited. To build a foundation necessary to engineer robust butanol-producing cyanobacterial hosts, in this study, the responses of Synechocystis PCC 6803 to butanol were investigated using a quantitative proteomics approach with iTRAQ - LC-MS/MS technologies. The resulting high-quality dataset consisted of 25,347 peptides corresponding to 1452 unique proteins, a coverage of approximately 40% of the predicted proteins in Synechocystis. Comparative quantification of protein abundances led to the identification of 303 differentially regulated proteins by butanol. Annotation and GO term enrichment analysis showed that multiple biological processes were regulated, suggesting that Synechocystis probably employed multiple and synergistic resistance mechanisms in dealing with butanol stress. Notably, the analysis revealed the induction of heat-shock protein and transporters, along with modification of cell membrane and envelope were the major protection mechanisms against butanol. A conceptual cellular model of Synechocystis PCC 6803 responses to butanol stress was constructed to illustrate the putative molecular mechanisms employed to defend against butanol stress.

  4. Carbon neutral electricity production by Synechocystis sp. PCC6803 in a microbial fuel cell.

    Science.gov (United States)

    Madiraju, Kartik S; Lyew, Darwin; Kok, Robert; Raghavan, Vijaya

    2012-04-01

    The aim of this work was to illustrate the use of photosynthetic microbes in a microbial fuel cell to produce electricity without the requirement of an external carbon source. This research here describes the use of a cyanobacterium Synechocystis PCC6803, to produce electricity without any net CO(2) production in a two-chambered MFC. Conditions for optimum electricity production were determined through standardizing operating parameters. A maximum power density of 6.7mWm(-3)(anode chamber volume) was achieved under high intensity lighting (10,000lux). Light intensity and wavelength directly affected electricity production, indicating the pivotal role played by photosynthesis. The maximum removal of CO(2) was 625mmolm(-3) over 20h under high intensity light. The results presented here will contribute to the understanding of how cyanobacteria can be exploited for the direct conversion of CO(2) to electric current.

  5. Characterization of a key gene in membrane lipid cycle in Synechocystis sp.PCC6803%集胞藻PCC6803膜脂循环关键基因酶学性质和生理功能

    Institute of Scientific and Technical Information of China (English)

    高倩倩; 谈晓明; 吕雪峰

    2012-01-01

    集胞藻PCC6803野生型和其脂酰ACP合酶敲除突变株的自由脂肪酸含量和组成表明膜脂的重构和降解是细胞内自由脂肪酸的来源之一.在这一过程中脂肪酶起到关键性作用.通过基因组数据库检索,发现集胞藻PCC6803基因组中只有一个脂肪酶编码基因sll1969,但是还没有其功能相关的生化证据.为了确定该基因的功能及其在脂肪酸代谢途径中的作用,加深对集胞藻PCC6803脂肪酸代谢途径的了解,文中将sll1969基因在大肠杆菌中过表达和体外纯化,得到重组蛋白Sl11969,并对其酶学性质进行初步分析.在30℃条件下,测得Sl11969以对硝基苯丁酸酯作为底物时的Km和Km和kcat值分别为(1.16--0.01)mmol/L和(332.8±10.0)/min;该脂肪酶的最适反应温度为55℃.通过比较分析sll1969突变株中脂肪酸含量和组成变化,发现sll1969的表达量与细胞自由脂肪酸的产量呈正相关,但S111969不是细胞中唯一的脂肪酶.%Free fatty acid profiles of wild type and fatty acyl-ACP synthase deletion mutant strain of Synechocystis sp. PCC6803 indicated that one origin of these fatty acids is the process of lipid remodeling or lipid degradation. Lipase is the key enzyme involved in this process. The gene sill 969 is the sole gene encodes a putative lipase in Synechocystis sp. PCC6803. To identify the function of this gene and its role in fatty acid metabolism, we cloned the sll1969 from genomic DNA, overexpressed it in Escherichia coli BL21 (DE3) using pET expression system and purified this recombinant enzyme with Nickel-nitrilotriacetic acid affinity chromatography. The enzyme activity was assayed by spectrophotometric with p-nitro-phenylbutyrate as substrate. The Km and Kcat of the enzyme is (1.16±0.01) mmol/L and (332.8±10.0)/min, respectively toward p-nitro-phenylbutyrate at 30℃. The optimal temperature of the enzyme is 55℃. To investigate the biological role of S111969 in fatty acid metabolism in

  6. Biosafety of biotechnologically important microalgae: intrinsic suicide switch implementation in cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Čelešnik, Helena; Tanšek, Anja; Tahirović, Aneja; Vižintin, Angelika; Mustar, Jernej; Vidmar, Vita; Dolinar, Marko

    2016-01-01

    In recent years, photosynthetic autotrophic cyanobacteria have attracted interest for biotechnological applications for sustainable production of valuable metabolites. Although biosafety issues can have a great impact on public acceptance of cyanobacterial biotechnology, biosafety of genetically modified cyanobacteria has remained largely unexplored. We set out to incorporate biocontainment systems in the model cyanobacteriumSynechocystissp. PCC 6803. Plasmid-encoded safeguards were constructed using the nonspecific nuclease NucA fromAnabaenacombined with different metal-ion inducible promoters. In this manner, conditional lethality was dependent on intracellular DNA degradation for regulated autokilling as well as preclusion of horizontal gene transfer. In cells carrying the suicide switch comprising thenucAgene fused to a variant of thecopMpromoter, efficient inducible autokilling was elicited. Parallel to nuclease-based safeguards, cyanobacterial toxin/antitoxin (TA) modules were examined in biosafety switches. Rewiring ofSynechocystisTA pairsssr1114/slr0664andslr6101/slr6100for conditional lethality using metal-ion responsive promoters resulted in reduced growth, rather than cell killing, suggesting cells could cope with elevated toxin levels. Overall, promoter properties and translation efficiency influenced the efficacy of biocontainment systems. Several metal-ion promoters were tested in the context of safeguards, and selected promoters, including anrsBvariant, were characterized by beta-galactosidase reporter assay.

  7. Serine/threonine protein kinase SpkG is a candidate for high salt resistance in the unicellular cyanobacterium Synechocystis sp. PCC 6803.

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    Chengwei Liang

    Full Text Available BACKGROUND: Seven serine/threonine kinase genes have been predicted in unicellular cyanobacterium Synechocystis sp. PCC6803. SpkA and SpkB were shown to be required for cell motility and SpkE has no kinase activity. There is no report whether the other four STKs are involved in stress-mediated signaling in Synechocystis PCC6803. METHODOLOGY/PRINCIPAL FINDINGS: In this paper, we examined differential expression of the other four serine/threonine kinases, SpkC, SpkD, SpkF and SpkG, at seven different stress conditions. The transcriptional level was up-regulated of spkG and down-regulated of spkC under high salt stress condition. Two spk deletion mutants, ΔspkC and ΔspkG, were constructed and their growth characteristic were examined compared to the wild strain. The wild strain and ΔspkC mutant were not affected under high salt stress conditions. In contrast, growth of spkG mutant was completely impaired. To further confirm the function of spkG, we also examined the effect of mutation of spkG on the expression of salt stress-inducible genes. We compared genome-wide patterns of transcription between wild-type Synechocystis sp. PCC6803 and cells with a mutation in the SpkG with DNA microarray analysis. CONCLUSION: In this study, we first study the spkG gene as sensor of high salt signal. We consider that SpkG play essential roles in Synechocystis sp. for sensing the high salt signal directly, rather than mediating signals among other kinases. Our microarray experiment may help select relatively significant genes for further research on mechanisms of signal transduction of Synechocystis sp. PCC6803 under high salt stress.

  8. Transduction of the light signal during complementary chromatic adaptation in the cyanobacterium Calothrix sp. PCC 7601: DNA-binding proteins and modulation by phosphorylation.

    OpenAIRE

    Sobczyk, A.; Schyns, G; Tandeau de Marsac, N.; Houmard, J

    1993-01-01

    The cyanobacterium Calothrix sp. PCC 7601 can adapt its pigment content in response to changes in the incident light wavelength. It synthesizes, as major light-harvesting pigments, either phycocyanin 2 (PC2, encoded by the cpc2 operon) under red light or phycoerythrin (PE, encoded by the cpeBA operon) under green light conditions. The last step of the signal transduction pathway is characterized by a transcriptional control of the expression of these operons. Partially purified protein extrac...

  9. Proteomic analysis reveals resistance mechanism against biofuel hexane in Synechocystis sp. PCC 6803

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    Liu Jie

    2012-09-01

    Full Text Available Abstract Background Recent studies have demonstrated that photosynthetic cyanobacteria could be an excellent cell factory to produce renewable biofuels and chemicals due to their capability to utilize solar energy and CO2 as the sole energy and carbon sources. Biosynthesis of carbon-neutral biofuel alkanes with good chemical and physical properties has been proposed. However, to make the process economically feasible, one major hurdle to improve the low cell tolerance to alkanes needed to be overcome. Results Towards the goal to develop robust and high-alkane-tolerant hosts, in this study, the responses of model cyanobacterial Synechocystis PCC 6803 to hexane, a representative of alkane, were investigated using a quantitative proteomics approach with iTRAQ - LC-MS/MS technologies. In total, 1,492 unique proteins were identified, representing about 42% of all predicted protein in the Synechocystis genome. Among all proteins identified, a total of 164 and 77 proteins were found up- and down-regulated, respectively. Functional annotation and KEGG pathway enrichment analyses showed that common stress responses were induced by hexane in Synechocystis. Notably, a large number of transporters and membrane-bound proteins, proteins against oxidative stress and proteins related to sulfur relay system and photosynthesis were induced, suggesting that they are possibly the major protection mechanisms against hexane toxicity. Conclusion The study provided the first comprehensive view of the complicated molecular mechanism employed by cyanobacterial model species, Synechocystis to defend against hexane stress. The study also provided a list of potential targets to engineer Synechocystis against hexane stress.

  10. ClpB1 overproduction in Synechocystis sp. strain PCC 6803 increases tolerance to rapid heat shock.

    Science.gov (United States)

    Gonzalez-Esquer, C Raul; Vermaas, Wim F J

    2013-10-01

    ClpB1 is a heat shock protein known to disaggregate large protein complexes. Constitutive, 16-fold ClpB1 overproduction in the cyanobacterium Synechocystis sp. strain PCC 6803 increased cell survival by 20-fold when cultures were heated quickly (1°C/s) to 50°C and delayed cell death by an average of 3 min during incubation at high temperatures (>46°C). Cooverexpression of ClpB1 and another heat shock protein, DnaK2, further increased cell survival. According to immunocytochemistry results, ClpB1 is dispersed throughout the cytoplasm but is concentrated in specific areas and is more prevalent near thylakoid membranes. However, ClpB1 overproduction does not lead to a change in the morphology, chlorophyll content, or photosystem ratio. Whereas electron microscopy demonstrated that apparent protein aggregation occurred after heat treatment in the control strain, protein aggregate size was maintained in the ClpB1 overexpresser. Constitutive ClpB1 overproduction allows an earlier response to heat shock and protects from rapid heating of cultures.

  11. Anaerobic Production of Hydrogen in the Dark by Synechocystis sp. strain PCC 6803 supplemented with D-glucose

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    Takashi Yamamoto

    2012-08-01

    Full Text Available The effect of D-glucose on the anaerobic production of hydrogen (H2 in the dark by bidirectional hydrogenase of Synechocystis sp. strain PCC 6803 has been studied. D-glucose addition enhanced H2 production rate. It is deduced that NAD(PH, which is a substrate of H2 production reaction, was supplied by catabolism of D-glucose. The molar consumption ratio of H2 and total sugar consumption was low in the presence of D-glucose due to production of L-lactic acid and other metabolites. The cells photosynthetically grown in air produced lower H2 in the dark as compared with those grown in air with 6% CO2, but the lower H2 production was compensated with the addition of D-glucose at 6.4 times of control value without D-glucose. The trend of effect of pH in a growth medium and a reaction mixture on H2 production was not affected by the presence of D-glucose. This result implies that mechanisms of H2 productions with and without D-glucose are similar.

  12. Inhibition of respiration and nitrate assimilation enhances photohydrogen evolution under low oxygen concentrations in Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Gutthann, Franziska; Egert, Melanie; Marques, Alexandra; Appel, Jens

    2007-02-01

    In cyanobacterial membranes photosynthetic light reaction and respiration are intertwined. It was shown that the single hydrogenase of Synechocystis sp. PCC 6803 is connected to the light reaction. We conducted measurements of hydrogenase activity, fermentative hydrogen evolution and photohydrogen production of deletion mutants of respiratory electron transport complexes. All single, double and triple mutants of the three terminal respiratory oxidases and the ndhB-mutant without a functional complex I were studied. After activating the hydrogenase by applying anaerobic conditions in the dark hydrogen production was measured at the onset of light. Under these conditions respiratory capacity and amount of photohydrogen produced were found to be inversely correlated. Especially the absence of the quinol oxidase induced an increased hydrogenase activity and an increased production of hydrogen in the light compared to wild type cells. Our results support that the hydrogenase as well as the quinol oxidase function as electron valves under low oxygen concentrations. When the activities of photosystem II and I (PSII and PSI) are not in equilibrium or in case that the light reaction is working at a higher pace than the dark reaction, the hydrogenase is necessary to prevent an acceptor side limitation of PSI, and the quinol oxidase to prevent an overreduction of the plastoquinone pool (acceptor side of PSII). Besides oxygen, nitrate assimilation was found to be an important electron sink. Inhibition of nitrate reductase resulted in an increased fermentative hydrogen production as well as higher amounts of photohydrogen.

  13. A Cytoplasmic Protein Ssl3829 Is Important for NDH-1 Hydrophilic Arm Assembly in Synechocystis sp. Strain PCC 6803.

    Science.gov (United States)

    Wang, Xiaozhuo; Gao, Fudan; Zhang, Jingsong; Zhao, Jiaohong; Ogawa, Teruo; Ma, Weimin

    2016-06-01

    Despite significant progress in clarifying the subunit compositions and functions of the multiple NDH-1 complexes in cyanobacteria, the assembly factors and their roles in assembling these NDH-1 complexes remain elusive. Two mutants sensitive to high light for growth and impaired in NDH-1-dependent cyclic electron transport around photosystem I were isolated from Synechocystis sp. strain PCC 6803 transformed with a transposon-tagged library. Both mutants were tagged in the ssl3829 gene encoding an unknown protein, which shares significant similarity with Arabidopsis (Arabidopsis thaliana) CHLORORESPIRATORY REDUCTION7. The ssl3829 product was localized in the cytoplasm and associates with an NDH-1 hydrophilic arm assembly intermediate (NAI) of about 300 kD (NAI300) and an NdhI maturation factor, Slr1097. Upon deletion of Ssl3829, the NAI300 complex was no longer visible on gels, thereby impeding the assembly of the NDH-1 hydrophilic arm. The deletion also abolished Slr1097 and consequently reduced the amount of mature NdhI in the cytoplasm, which repressed the dynamic assembly process of the NDH-1 hydrophilic arm because mature NdhI was essential to stabilize all functional NAIs. Therefore, Ssl3829 plays an important role in the assembly of the NDH-1 hydrophilic arm by accumulating the NAI300 complex and Slr1097 protein in the cytoplasm.

  14. 13C-MFA delineates the photomixotrophic metabolism of Synechocystis sp. PCC 6803 under light- and carbon-sufficient conditions.

    Science.gov (United States)

    You, Le; Berla, Bert; He, Lian; Pakrasi, Himadri B; Tang, Yinjie J

    2014-05-01

    The central carbon metabolism of cyanobacteria is under debate. For over 50 years, the lack of α-ketoglutarate dehydrogenase has led to the belief that cyanobacteria have an incomplete TCA cycle. Recent in vitro enzymatic experiments suggest that this cycle may in fact be closed. The current study employed (13) C isotopomers to delineate pathways in the cyanobacterium Synechocystis sp. PCC 6803. By tracing the incorporation of supplemented glutamate into the downstream metabolites in the TCA cycle, we observed a direct in vivo transformation of α-ketoglutarate to succinate. Additionally, isotopic tracing of glyoxylate did not show a functional glyoxylate shunt and glyoxylate was used for glycine synthesis. The photomixotrophic carbon metabolism was then profiled with (13) C-MFA under light and carbon-sufficient conditions. We observed that: (i) the in vivo flux through the TCA cycle reactions (α-ketoglutarate → succinate) was minimal (<2%); (ii) the flux ratio of CO2 fixation was six times higher than that of glucose utilization; (iii) the relative flux through the oxidative pentose phosphate pathway was low (<2%); (iv) high flux through malic enzyme served as a main route for pyruvate synthesis. Our results improve the understanding of the versatile metabolism in cyanobacteria and shed light on their application for photo-biorefineries.

  15. Metabolic engineering and comparative performance studies of Synechocystis sp. PCC 6803 strains for effective utilization of xylose.

    Directory of Open Access Journals (Sweden)

    Saurabh eRanade

    2015-12-01

    Full Text Available Wood sugars such as xylose can be used as an inexpensive carbon source for biotechnological applications. The model cyanobacterium Synechocystis sp. PCC 6803 lacks the ability to catabolize wood sugars as an energy source. Here, we generated four Synechocystis strains that heterologously expressed XylAB enzymes, which mediate xylose catabolism, either in combination with or without one of three xylose transporters, namely XylE, GalP, or Glf. Except for glf, which is derived from the bacterium Zymomonas mobilis ZM4, the heterologous genes were sourced from Escherichia coli K-12. All of the recombinant strains were able to utilize xylose in the absence of catabolite repression. When xylose was the lone source of organic carbon, strains possessing the XylE and Glf transporters were most efficient in terms of dry biomass production and xylose consumption and the strain lacking a heterologous transporter was the least efficient. However, in the presence of a xylose-glucose mixed sugar source, the strains exhibited similar levels of growth and xylose consumption. This study demonstrates that various bacterial xylose transporters can boost xylose catabolism in transgenic Synechocystis strains, and paves the way for the sustainable production of bio-compounds and green fuels from lignocellulosic biomass.

  16. Physiological regulation of isocitrate dehydrogenase and the role of 2-oxoglutarate in Prochlorococcus sp. strain PCC 9511.

    Science.gov (United States)

    Domínguez-Martín, María Agustina; López-Lozano, Antonio; Diez, Jesús; Gómez-Baena, Guadalupe; Rangel-Zúñiga, Oriol Alberto; García-Fernández, José Manuel

    2014-01-01

    The enzyme isocitrate dehydrogenase (ICDH; EC 1.1.1.42) catalyzes the oxidative decarboxylation of isocitrate, to produce 2-oxoglutarate. The incompleteness of the tricarboxylic acids cycle in marine cyanobacteria confers a special importance to isocitrate dehydrogenase in the C/N balance, since 2-oxoglutarate can only be metabolized through the glutamine synthetase/glutamate synthase pathway. The physiological regulation of isocitrate dehydrogenase was studied in cultures of Prochlorococcus sp. strain PCC 9511, by measuring enzyme activity and concentration using the NADPH production assay and Western blotting, respectively. The enzyme activity showed little changes under nitrogen or phosphorus starvation, or upon addition of the inhibitors DCMU, DBMIB and MSX. Azaserine, an inhibitor of glutamate synthase, induced clear increases in the isocitrate dehydrogenase activity and icd gene expression after 24 h, and also in the 2-oxoglutarate concentration. Iron starvation had the most significant effect, inducing a complete loss of isocitrate dehydrogenase activity, possibly mediated by a process of oxidative inactivation, while its concentration was unaffected. Our results suggest that isocitrate dehydrogenase responds to changes in the intracellular concentration of 2-oxoglutarate and to the redox status of the cells in Prochlorococcus.

  17. Physiological regulation of isocitrate dehydrogenase and the role of 2-oxoglutarate in Prochlorococcus sp. strain PCC 9511.

    Directory of Open Access Journals (Sweden)

    María Agustina Domínguez-Martín

    Full Text Available The enzyme isocitrate dehydrogenase (ICDH; EC 1.1.1.42 catalyzes the oxidative decarboxylation of isocitrate, to produce 2-oxoglutarate. The incompleteness of the tricarboxylic acids cycle in marine cyanobacteria confers a special importance to isocitrate dehydrogenase in the C/N balance, since 2-oxoglutarate can only be metabolized through the glutamine synthetase/glutamate synthase pathway. The physiological regulation of isocitrate dehydrogenase was studied in cultures of Prochlorococcus sp. strain PCC 9511, by measuring enzyme activity and concentration using the NADPH production assay and Western blotting, respectively. The enzyme activity showed little changes under nitrogen or phosphorus starvation, or upon addition of the inhibitors DCMU, DBMIB and MSX. Azaserine, an inhibitor of glutamate synthase, induced clear increases in the isocitrate dehydrogenase activity and icd gene expression after 24 h, and also in the 2-oxoglutarate concentration. Iron starvation had the most significant effect, inducing a complete loss of isocitrate dehydrogenase activity, possibly mediated by a process of oxidative inactivation, while its concentration was unaffected. Our results suggest that isocitrate dehydrogenase responds to changes in the intracellular concentration of 2-oxoglutarate and to the redox status of the cells in Prochlorococcus.

  18. RNA-seq profiling reveals novel target genes of LexA in the cyanobacterium Synechocystis sp. PCC 6803

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    Ayumi eKizawa

    2016-02-01

    Full Text Available LexA is a well-established transcriptional repressor of SOS genes induced by DNA damage in E. coli and other bacterial species. However, LexA in the cyanobacterium Synechocystis sp. PCC 6803 has been suggested not to be involved in SOS response. In this study, we performed RNA-seq analysis of the wild-type strain and the lexA-disrupted mutant to obtain the comprehensive view of LexA-regulated genes in Synechocystis. Disruption of lexA positively or negatively affected expression of genes related to various cellular functions such as phototactic motility, accumulation of the major compatible solute glucosylglycerol and subunits of bidirectional hydrogenase, photosystem I and phycobilisome complexes. We also observed increase in the expression level of genes related to iron and manganese uptake in the mutant at the later stage of cultivation. However, none of the genes related to DNA metabolism were affected by disruption of lexA. DNA gel mobility shift assay using the recombinant LexA protein suggested that LexA binds to the upstream region of pilA7, pilA9, ggpS and slr1670 to directly regulate their expression, but changes in the expression level of photosystem I genes by disruption of lexA is likely a secondary effect.

  19. Acrolein, an α,β-unsaturated carbonyl, inhibits both growth and PSII activity in the cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Shimakawa, Ginga; Iwamoto, Tatsuya; Mabuchi, Tomohito; Saito, Ryota; Yamamoto, Hiroshi; Amako, Katsumi; Sugimoto, Toshio; Makino, Amane; Miyake, Chikahiro

    2013-01-01

    In this study, we sought to determine whether and how an α,β-unsaturated carbonyl, acrolein, can inhibit the growth of the cyanobacterium Synechocystis sp. PCC6803 (S. 6803). Treatment of S. 6803 with 200 µM acrolein for 3 d significantly and irreversibly inhibited its growth. To elucidate the inhibitory mechanism, we examined the effects of acrolein on photosynthesis. In contrast to dark conditions, the addition of acrolein to S. 6803 under conditions of illumination lowered the CO₂-dependent O₂ evolution rate (photosynthetic activity). Furthermore, treatment with acrolein lowered the activity reducing dimethyl benzoquinone in photosystem II (PSII). Acrolein also suppressed the reduction rate for the oxidized form of the reaction center chlorophyll of photosystem I (PSI), P700. These results indicate that acrolein inhibited PSII activity in thylakoid membranes. The addition of 200 µM acrolein to the illuminated S. 6803 cells gradually increased the steady-state level (Fs) of Chl fluorescence and decreased the quantum yield of PSII. These results suggested that acrolein damaged the acceptor side of PSII. On the other hand, acrolein did not inhibit respiration. From the above results, we gained insight into the metabolism of acrolein and its physiological effects in S. 6803.

  20. Enhancement of poly-3-hydroxybutyrate production in Synechocystis sp. PCC 6803 by overexpression of its native biosynthetic genes.

    Science.gov (United States)

    Khetkorn, Wanthanee; Incharoensakdi, Aran; Lindblad, Peter; Jantaro, Saowarath

    2016-08-01

    Synechocystis sp. PCC 6803 strains overexpressing pha genes were constructed and characterized for poly-3-hydroxybutyrate (PHB) production. These pha overexpressing strains showed slightly reduced growth rates. Under N-deprived condition, the strains overexpressing (OE) phaAB, phaEC and phaABEC showed significantly higher PHB contents than the wild type. The maximum PHB content, a 2.6-fold increase producing 26% PHB (dcw), was observed in OE phaAB cells grown for 9days in N-deprived medium. Under this condition, these OE phaAB cells increased PHB production to 35% PHB (dcw) upon addition of 0.4% (w/v) acetate. Higher PHB granules in OE phaAB cells were clearly visualized by both Nile red staining and TEM imaging. All OE strains under N-deficient condition had increased glgX transcript levels. Overall results demonstrate an enhanced PHB production in Synechocystis cells overexpressing pha genes, particularly phaA and phaB, when grown in N-deprived medium containing 0.4% (w/v) acetate.

  1. New insight into the cleavage reaction of Nostoc sp. strain PCC 7120 carotenoid cleavage dioxygenase in natural and nonnatural carotenoids.

    Science.gov (United States)

    Heo, Jinsol; Kim, Se Hyeuk; Lee, Pyung Cheon

    2013-06-01

    Carotenoid cleavage dioxygenases (CCDs) are enzymes that catalyze the oxidative cleavage of carotenoids at a specific double bond to generate apocarotenoids. In this study, we investigated the activity and substrate preferences of NSC3, a CCD of Nostoc sp. strain PCC 7120, in vivo and in vitro using natural and nonnatural carotenoid structures. NSC3 cleaved β-apo-8'-carotenal at 3 positions, C-13 C-14, C-15 C-15', and C-13' C-14', revealing a unique cleavage pattern. NSC3 cleaves the natural structure of carotenoids 4,4'-diaponeurosporene, 4,4'-diaponeurosporen-4'-al, 4,4'-diaponeurosporen-4'-oic acid, 4,4'-diapotorulene, and 4,4'-diapotorulen-4'-al to generate novel cleavage products (apo-14'-diaponeurosporenal, apo-13'-diaponeurosporenal, apo-10'-diaponeurosporenal, apo-14'-diapotorulenal, and apo-10'-diapotorulenal, respectively). The study of carotenoids with natural or nonnatural structures produced by using synthetic modules could provide information valuable for understanding the cleavage reactions or substrate preferences of other CCDs in vivo and in vitro.

  2. Seawater cultivation of freshwater cyanobacterium Synechocystis sp. PCC 6803 drastically alters amino acid composition and glycogen metabolism

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    Hiroko eIijima

    2015-04-01

    Full Text Available Water use assessment is important for bioproduction using cyanobacteria. For eco-friendly reasons, seawater should preferably be used for cyanobacteria cultivation instead of freshwater. In this study, we demonstrated that the freshwater unicellular cyanobacterium Synechocystis sp. PCC 6803 could be grown in a medium based on seawater. The Synechocystis wild-type strain grew well in an artificial seawater (ASW medium supplemented with nitrogen and phosphorus sources. The addition of HEPES buffer improved cell growth overall, although the growth in ASW medium was inferior to that in the synthetic BG-11 medium. The levels of proteins involved in sugar metabolism changed depending on the culture conditions. The biosynthesis of several amino acids including aspartate, glutamine, glycine, proline, ornithine, and lysine, was highly up-regulated by cultivation in ASW. Two types of natural seawater (NSW were also made available for the cultivation of Synechocystis cells, with supplementation of both nitrogen and phosphorus sources. These results revealed the potential use of seawater for the cultivation of freshwater cyanobacteria, which would help to reduce freshwater consumption during biorefinery using cyanobacteria.

  3. Trophic Mode-Dependent Proteomic Analysis Reveals Functional Significance of Light-Independent Chlorophyll Synthesis in Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Fang, Longfa; Ge, Haitao; Huang, Xiahe; Liu, Ye; Lu, Min; Wang, Jinlong; Chen, Weiyang; Xu, Wu; Wang, Yingchun

    2017-01-09

    The photosynthetic model organism Synechocystis sp. PCC 6803 can grow in different trophic modes, depending on the availability of light and exogenous organic carbon source. However, how the protein profile changes to facilitate the cells differentially propagate in different modes has not been comprehensively investigated. Using isobaric labeling-based quantitative proteomics, we simultaneously identified and quantified 45% Synechocystis proteome across four different trophic modes, i.e., autotrophic, heterotrophic, photoheterotrophic, and mixotrophic modes. Among the 155 proteins that are differentially expressed across four trophic modes, proteins involved in nitrogen assimilation and light-independent chlorophyll synthesis are dramatically upregulated in the mixotrophic mode, concomitant with a dramatic increase of PII phosphorylation that senses carbon and nitrogen assimilation status. Moreover, functional study using a mutant defective in light-independent chlorophyll synthesis revealed that this pathway is important for chlorophyll accumulation under a cycled light/dark illumination regime, a condition mimicking day/night cycles in certain natural habitats. Collectively, these results provide the most comprehensive information on trophic mode-dependent protein expression in cyanobacterium, and reveal the functional significance of light-independent chlorophyll synthesis in trophic growth.

  4. Recombinant PsbF from Synechococcus sp. PCC 7002 forms β:βhomodimeric cytochrome b559

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    All organisms with oxygenic photosynthesis contain two photosystems: photosystemⅠ(PSⅠ) and photosystem-Ⅱ-(PSⅡ). The minimal photosystem-Ⅱ-particles which are photochemically active contain three subunits: D1, D2 and cytochrome b559 (Cyt b559). The function of Cyt b559 remains unclear. We have successfully overexpressed the psbF gene, encoding the - subunit of Cyt b559, from a marine cyanobacterium Synechococcus sp. PCC 7002 as a fusion gene and obtained a redox-active form of Cyt b559. When the N-terminal GST protein of the fusion gene product was removed with thrombin, the PsbF protein was still redox-active, suggesting that the recombinant PsbF can form dimer in Escherichia coli. The absorption spectra of either the oxidized form or the reduced form of both GST fusion protein and the purified PsbF dimer and the difference spectra between the two forms are the same as that of the Cyt b559 isolated from the higher plants. Redox titration analysis of recombinant PsbF showed that the mid-point redox potential of the recombinant Cyt b559 was approximately 50 mV, which is close to the low potential of Cyt b559. The results are helpful to the understanding of localization and function of Cyt b559 on thylakoid membranes.

  5. Study on Absorption and Transformation of Arsenic in Blue Alga (Synechocystis sp.PCC6803)%集胞藻(Synechocystis sp. PCC6803)对砷吸收转化特性的初步研究

    Institute of Scientific and Technical Information of China (English)

    张兵; 王利红; 徐玉新; 尹西翔

    2011-01-01

    砷是一种广泛存在于环境中的有毒物质.集胞藻属于单细胞藻类,广泛分布在淡水生态环境中.采用营养液培养的方法探讨了集胞藻(Synechocystis sp.PCC6803)对砷的累积和转化特性.当集胞藻分别暴露于2和100 μM的无机As(Ⅲ)和As(Ⅴ)14 d后,体内的砷形态均以As(Ⅴ)为主,并且在100 μM浓度处理下检测到DMA,结果表明集胞藻体内存在砷的氧化和还原机制,只有高浓度砷才能诱导集胞藻体内的砷甲基化机制起作用.研究了集胞藻在含磷培养基中对不同形态砷的吸收动力学特征,As(Ⅲ)的最大吸收速率大于As(Ⅴ)的最大吸收速率,而集胞藻对As(Ⅴ)的亲和性大于As(Ⅲ).考察了集胞藻对含砷溶液的净化作用,72 h集胞藻净化效率能达到41%,此结果表明集胞藻具有修复砷污染水体的潜力.%Arsenic (As) is a highly toxic and widespread environmental contaninant. Synechocystics belongs to unicallular algae which is widely distributed in fresh-water. Synechocystis sp. PCC6803 cultivated in medium was exposed to arsenite and arsenate in order to investigate uptake, accumulation and transformation of arsenic species in Synechocystis. After exposed to both arsenite (2 jjlM) and arsenate (100 u,M ) 14 days, As(V) was the main species in Synechocystis. DMA was detected in Synechocystis treated with arsenate at 100 μM. The result showed that mechanisms of arsenic reduction and oxidation were present in Synechocystis simultaneously, and mechanisms of arsenic methylation only can be induced at high concentration of arsenate. The kinetics of arsenite and arsenate uptake of Synechocystise showed that the the uptake rate of As(Ⅲ) was faster than that of As(V), while the affinity of As(V) was higher than that of As(Ⅲ) in Synechocystis. Purification effect of Synechocystis for arsenic solution was studied as well. Purification efficiency of Synechocystis can reach 41% in 72 hours, that clarified Synechocystis have the

  6. Regulation of Development and Nitrogen Fixation in Anabaena

    Energy Technology Data Exchange (ETDEWEB)

    James W. Golden

    2008-10-17

    The regulation of development and cellular differentiation is important for all multicellular organisms. The nitrogen-fixing filamentous cyanobacterium Anabaena (also Nostoc) sp. PCC 7120 (hereafter Anabaena) provides a model of multicellular microbial development and pattern formation. Anabaena reduces N2 to ammonia in specialized terminally differentiated cells called heterocysts. A one-dimensional developmental pattern of single heterocysts regularly spaced along filaments of photosynthetic vegetative cells is established to form a multicellular organism composed of these two interdependent cell types. This multicellular growth pattern, the distinct phylogeny of cyanobacteria, and the suspected antiquity of heterocyst development make this an important model system. Our long-term goal is to understand the regulatory network required for heterocyst development and nitrogen fixation. This project is focused on two key aspects of heterocyst regulation: one, the mechanism by which HetR controls the initiation of differentiation, and two, the cis and trans acting factors required for expression of the nitrogen-fixation (nif) genes. HetR is thought to be a central regulator of heterocyst development but the partners and mechanisms involved in this regulation are unknown. Our recent results indicate that PatS and other signals that regulate heterocyst pattern cannot interact, directly or indirectly, with a R223W mutant of HetR. We plan to use biochemical and genetic approaches to identify proteins that interact with the HetR protein, which will help reveal the mechanisms underlying its regulation of development. Our second goal is to determine how the nif genes are expressed. It is important to understand the mechanisms controlling nif genes since they represent the culmination of the differentiation process and the essence of heterocyst function. The Anabaena genome lacks the genes required for expression of nif genes present in other organisms such as rpoN (sigma 54

  7. Evaluating Light-Induced Promoters for the Control of Heterologous Gene Expression in Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Albers, Stevan C; Peebles, Christie A M

    2017-01-01

    Cyanobacteria are enticing microbial factories, but little is understood how their gene control elements respond to the periodic availability to light. This research tested the capability of PpsbAII to control gene expression during light/dark conditions when moved to a neutral location within the Synechocystis sp. PCC 6803 genome. When the eYFP reporter gene was run by PpsbAII in the promoter's native genomic location, mutants exposed to 12-hour light conditions experienced a 15.8× increase in transcript abundance over that observed from the same construct exposed to 12-hour dark conditions. When this same construct was moved to the hypothetical coding region slr0168 in the genome, transcripts generated during 12 hour light conditions accumulated to 1.67X of the levels of transcripts generated by the same construct during 12 hour dark conditions. Three additional promoter constructs, PpsbAIII , PgroEL2 , and PsigD were also tested for differential expression in light and dark conditions within the neutral region slr0168. While low amounts of transcript accumulation were observed from PgroEL2 and PsigD , the PpsbAIII construct accumulated 5.79× more transcripts when compared to transcript abundance during dark conditions, which highlights the potential of this promoter to control gene expression during diel-cycle light conditions. Additionally, nucleotide mutations were made to regions within PpsbAII . Mutations to the cis-acting hexo-nucleotide region increased expression 3.71× over that of the native promoter, while the addition of the "HLR" nucleotide region to the PpsbAII::ΔHex construct increased expression 2.76× over that of the native promoter. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:45-53, 2017.

  8. Inactivation of nitrate reductase alters metabolic branching of carbohydrate fermentation in the cyanobacterium Synechococcus sp. strain PCC 7002.

    Science.gov (United States)

    Qian, Xiao; Kumaraswamy, G Kenchappa; Zhang, Shuyi; Gates, Colin; Ananyev, Gennady M; Bryant, Donald A; Dismukes, G Charles

    2016-05-01

    To produce cellular energy, cyanobacteria reduce nitrate as the preferred pathway over proton reduction (H2 evolution) by catabolizing glycogen under dark anaerobic conditions. This competition lowers H2 production by consuming a large fraction of the reducing equivalents (NADPH and NADH). To eliminate this competition, we constructed a knockout mutant of nitrate reductase, encoded by narB, in Synechococcus sp. PCC 7002. As expected, ΔnarB was able to take up intracellular nitrate but was unable to reduce it to nitrite or ammonia, and was unable to grow photoautotrophically on nitrate. During photoautotrophic growth on urea, ΔnarB significantly redirects biomass accumulation into glycogen at the expense of protein accumulation. During subsequent dark fermentation, metabolite concentrations--both the adenylate cellular energy charge (∼ATP) and the redox poise (NAD(P)H/NAD(P))--were independent of nitrate availability in ΔnarB, in contrast to the wild type (WT) control. The ΔnarB strain diverted more reducing equivalents from glycogen catabolism into reduced products, mainly H2 and d-lactate, by 6-fold (2.8% yield) and 2-fold (82.3% yield), respectively, than WT. Continuous removal of H2 from the fermentation medium (milking) further boosted net H2 production by 7-fold in ΔnarB, at the expense of less excreted lactate, resulting in a 49-fold combined increase in the net H2 evolution rate during 2 days of fermentation compared to the WT. The absence of nitrate reductase eliminated the inductive effect of nitrate addition on rerouting carbohydrate catabolism from glycolysis to the oxidative pentose phosphate (OPP) pathway, indicating that intracellular redox poise and not nitrate itself acts as the control switch for carbon flux branching between pathways.

  9. Roles of Group 2 Sigma Factors in Acclimation of the Cyanobacterium Synechocystis sp. PCC 6803 to Nitrogen Deficiency.

    Science.gov (United States)

    Antal, Taras; Kurkela, Juha; Parikainen, Marjaana; Kårlund, Anna; Hakkila, Kaisa; Tyystjärvi, Esa; Tyystjärvi, Taina

    2016-06-01

    Acclimation of cyanobacteria to environmental conditions is mainly controlled at the transcriptional level, and σ factors of the RNA polymerase have a central role in this process. The model cyanobacterium Synechocystis sp. PCC 6803 has four non-essential group 2 σ factors (SigB, SigC, SigD and SigE) that regulate global metabolic responses to various adverse environmental conditions. Here we show that although none of the group 2 σ factors is essential for the major metabolic realignments induced by a short period of nitrogen starvation, the quadruple mutant without any group 2 σ factors and triple mutants missing both SigB and SigD grow slowly in BG-11 medium containing only 5% of the nitrate present in standard BG-11. These ΔsigBCDE, ΔsigBCD and ΔsigBDE strains lost PSII activity rapidly in low nitrogen and accumulated less glycogen than the control strain. An abnormally high glycogen content was detected in ΔsigBCE (SigD is active), while the carotenoid content became high in ΔsigCDE (SigB is active), indicating that SigB and SigD regulate the partitioning of carbon skeletons in low nitrogen. Long-term survival and recovery of the cells after nitrogen deficiency was strongly dependent on group 2 σ factors. The quadruple mutant and the ΔsigBDE strain (only SigC is active) recovered more slowly from nitrogen deficiency than the control strain, and ΔsigBCDE in particular lost viability during nitrogen starvation. Nitrogen deficiency-induced changes in the pigment content of the control strain recovered essentially in 1 d in nitrogen-replete medium, but little recovery occurred in ΔsigBCDE and ΔsigBDE.

  10. Functional studies of the gene slr2049 from Synechocystis sp. PCC6803 and its site-directed mutation.

    Science.gov (United States)

    Liu, Bingjun; Chen, Sili; Zhang, Lei

    2015-06-01

    Phycobiliprotein is a homologous family of light-harvesting chromoproteins existing in cyanobacteria, red algae and cryptophytes. Phycobiliprotein is made up of phycobilin and its corresponding apophycobiliprotein, and they are covalently linked by the thioether bond with the bilin lyase. Using the software BLAST, we have found gene slr2049 in Synechocystis sp. PCC6803 homologous to the biliprotein lyase gene cpeS. This paper investigates the protein expressed by gene slr2049 to find the enzymatic activity characteristics. We cloned slr2049 and its related genes cpcB, ho1, and pcyA which are linked with the synthesis of phycocyanin. Special amino acid mutagenesis was performed on slr2049 to construct eight mutants slr2049 (H21S), slr2049 (L23S), slr2049 (A24S), slr2049 (F25S), slr2049 (W72L), slr2049 (G84S), slr2049 (R107S) and slr2049 (Y124S). These mutants were ligated with vectors pEDFDuet-1 and pET-23a to construct pCDF-cpcB-slr2049 wild-type, pCDF-cpcB-slr2049 mutants and pET-ho1-pcyA, for the purpose of protein expression and analysis. The results showed that the wild-type and mutants slr2049 (H21S), slr2049 (L23S), slr2049 (F25S), slr2049 (W72L), slr2049 (G84S), and slr2049 (Y124S) can catalyze CpcB to couple on PCB correctly and the products have unique spectral characteristics. However mutants slr2049 (A24S) and slr2049 (R107S) have no spectral characteristics. Thus, it is suggested that alanine at position 24 and arginine at position 107 are the active sites.

  11. Identification of OmpR-family response regulators interacting with thioredoxin in the Cyanobacterium Synechocystis sp. PCC 6803.

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    Taro Kadowaki

    Full Text Available The redox state of the photosynthetic electron transport chain is known to act as a signal to regulate the transcription of key genes involved in the acclimation responses to environmental changes. We hypothesized that the protein thioredoxin (Trx acts as a mediator connecting the redox state of the photosynthetic electron transport chain and transcriptional regulation, and established a screening system to identify transcription factors (TFs that interact with Trx. His-tagged TFs and S-tagged mutated form of Trx, TrxMC35S, whose active site cysteine 35 was substituted with serine to trap the target interacting protein, were co-expressed in E. coli cells and Trx-TF complexes were detected by immuno-blotting analysis. We examined the interaction between Trx and ten OmpR family TFs encoded in the chromosome of the cyanobacterium Synechocystis sp. PCC 6803 (S.6803. Although there is a highly conserved cysteine residue in the receiver domain of all OmpR family TFs, only three, RpaA (Slr0115, RpaB (Slr0947 and ManR (Slr1837, were identified as putative Trx targets [corrected].The recombinant forms of wild-type TrxM, RpaA, RpaB and ManR proteins from S.6803 were purified following over-expression in E. coli and their interaction was further assessed by monitoring changes in the number of cysteine residues with free thiol groups. An increase in the number of free thiols was observed after incubation of the oxidized TFs with Trx, indicating the reduction of cysteine residues as a consequence of interaction with Trx. Our results suggest, for the first time, the possible regulation of OmpR family TFs through the supply of reducing equivalents from Trx, as well as through the phospho-transfer from its cognate sensor histidine kinase.

  12. Contributions of DPOR at Low Light Intensity to Chlorophyll Biosynthesis and Growth in the Synechocystis sp.PCC 6803

    Institute of Scientific and Technical Information of China (English)

    黄卫; 吴庆余; 余久久

    2004-01-01

    The chlL gene encoding one component of light-independent (dark) protochlorophyllide oxido reductase (DPOR) was deleted in cyanobacterium Synechocystis sp. PCC 6803 (S.6803). The resulting chlL mutant lost DPOR activity. No significant differences of chlorophyll (Chi) content and growth rate were observed between the wild and the mutant strains grown at 50 μE · m-2· s-1 light intensity for photomixtrophic and photoautotrophic growth. However, differences were observed at 1 μE · m-2 · s-1 light intensity. For photomixtrophic growth, the mutant Chi content was 50% of the wild content with continuous light and 35.7% of the wild content with a 10 h light/14 h dark cycle. For photoautotriphic growth, the mutant Chi level was 76.3% of the wild content with continuous light and 63.2% with a 10 h light/14 h dark cycle. The results indicate that DPOR contributes to Chi synthesis and increases the growth rate in cyanobacteria phototrophically cultured at 1μE · m-2 ·s-1 light intensity. In contrast, the photosynthetic capacity on a per-cell basis of the mutant is 5% higher than that of the wild strain with continuous light and 27% higher than that of the wild strain with a 10 h light/14 h dark cycle at 1 μE · m-2 · s-1 light intensity for photoautotrophic growth. With the low Chi content, the cyanobacteria have the ability to improve their photosynthetic capacity by decreasing the ratio of PSI to PSII by unknown morphological or physiological means.

  13. Lauric Acid Production in a Glycogen-Less Strain of Synechococcus sp. PCC 7002.

    Science.gov (United States)

    Work, Victoria H; Melnicki, Matthew R; Hill, Eric A; Davies, Fiona K; Kucek, Leo A; Beliaev, Alexander S; Posewitz, Matthew C

    2015-01-01

    The cyanobacterium Synechococcus sp. Pasteur culture collection 7002 was genetically engineered to synthesize biofuel-compatible medium-chain fatty acids (FAs) during photoautotrophic growth. Expression of a heterologous lauroyl-acyl carrier protein (C12:0-ACP) thioesterase with concurrent deletion of the endogenous putative acyl-ACP synthetase led to secretion of transesterifiable C12:0 FA in CO2-supplemented batch cultures. When grown at steady state over a range of light intensities in a light-emitting diode turbidostat photobioreactor, the C12-secreting mutant exhibited a modest reduction in growth rate and increased O2 evolution relative to the wild-type (WT). Inhibition of (i) glycogen synthesis by deletion of the glgC-encoded ADP-glucose pyrophosphorylase (AGPase) and (ii) protein synthesis by nitrogen deprivation were investigated as potential mechanisms for metabolite redistribution to increase FA synthesis. Deletion of AGPase led to a 10-fold decrease in reducing carbohydrates and secretion of organic acids during nitrogen deprivation consistent with an energy spilling phenotype. When the carbohydrate-deficient background (ΔglgC) was modified for C12 secretion, no increase in C12 was achieved during nutrient replete growth, and no C12 was recovered from any strain upon nitrogen deprivation under the conditions used. At steady state, the growth rate of the ΔglgC strain saturated at a lower light intensity than the WT, but O2 evolution was not compromised and became increasingly decoupled from growth rate with rising irradiance. Photophysiological properties of the ΔglgC strain suggest energy dissipation from photosystem II and reconfiguration of electron flow at the level of the plastoquinone pool.

  14. Effects of heavy metals (Pb2+ and Cd2+) on the ultrastructure, growth and pigment contents of the unicellular cyanobacterium Synechocystis sp. PCC 6803

    Institute of Scientific and Technical Information of China (English)

    K. K. I. U. Arunakumara; ZHANG Xuecheng

    2009-01-01

    The unicellular cyanobacterium Synechocystis sp. PCC 6803, a model organism known for its unique combination of highly desirable molecular genetic, physiological and morphological characteristics, was employed in the present study. The species was cultured in BG11 liquid medium contained various initial concentrations of Pb2+ and Cd2+ (0, 0.5, 1, 2, 4, 6 and 8 mg/L). The experiment was conducted for six days and the metal induced alterations in the ultrastructure, growth and pigment contents were assessed. Alterations in the ultrastructure of the Synechocystis sp. PCC 6803 ceils became evident with the increased (>4 mg/L Pb2+) metal concentration. The photosynthetic apparatus (thylakoid membranes) were found to be the worst affected. Deteriorated or completely destroyed thylakoid membranes have made large empty spaces in the cell interior. In addition, at the highest concentration (8 mg/L pb2+), the polyphosphate granules became more prominent both in size and number. Despite the initial slight stimulations (0.2, 3.8 and 6.5% respectively at 0.5, 1 and 2 mg/L Pb2+), both metals inhibited the growth in a dose-dependent manner as incubation progressed. Pigment contents (chlorophyll a, βcarotene and phycocyanin) were also decreased with increasing metal concentration. Cells exposed to 6 mg/L Pb2+, resulted in 36.56, 37.39 and 29.34% reductions of chlorophyll a, β carotene and phycocyanin respectively over the control. Corresponding reductions for the same Cd2+concentrations were 57.83, 48.94 and 56.90%. Lethal concentration (96 h LC50) values (3.47 mg/L Cd2+ and 12.11 mg/L Pb2+) indicated that Synechocystis sp. PCC 6803 is more vulnerable to Cd2+ than Pb2+.

  15. The nitrogen-regulated response regulator NrrA controls cyanophycin synthesis and glycogen catabolism in the cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Liu, Deng; Yang, Chen

    2014-01-24

    The cellular metabolism in cyanobacteria is extensively regulated in response to changes of environmental nitrogen availability. Multiple regulators are involved in this process, including a nitrogen-regulated response regulator NrrA. However, the regulatory role of NrrA in most cyanobacteria remains to be elucidated. In this study, we combined a comparative genomic reconstruction of NrrA regulons in 15 diverse cyanobacterial species with detailed experimental characterization of NrrA-mediated regulation in Synechocystis sp. PCC 6803. The reconstructed NrrA regulons in most species included the genes involved in glycogen catabolism, central carbon metabolism, amino acid biosynthesis, and protein degradation. A predicted NrrA-binding motif consisting of two direct repeats of TG(T/A)CA separated by an 8-bp A/T-rich spacer was verified by in vitro binding assays with purified NrrA protein. The predicted target genes of NrrA in Synechocystis sp. PCC 6803 were experimentally validated by comparing the transcript levels and enzyme activities between the wild-type and nrrA-inactivated mutant strains. The effect of NrrA deficiency on intracellular contents of arginine, cyanophycin, and glycogen was studied. Severe impairments in arginine synthesis and cyanophycin accumulation were observed in the nrrA-inactivated mutant. The nrrA inactivation also resulted in a significantly decreased rate of glycogen degradation. Our results indicate that by directly up-regulating expression of the genes involved in arginine synthesis, glycogen degradation, and glycolysis, NrrA controls cyanophycin accumulation and glycogen catabolism in Synechocystis sp. PCC 6803. It is suggested that NrrA plays a role in coordinating the synthesis and degradation of nitrogen and carbon reserves in cyanobacteria.

  16. Regulation of glutamine synthetase activity in the unicellular cyanobacterium Synechocystis sp. strain PCC 6803 by the nitrogen source: effect of ammonium.

    OpenAIRE

    Mérida, A; Candau, P; Florencio, F J

    1991-01-01

    Glutamine synthetase activity from Synechocystis sp. strain PCC 6803 is regulated as a function of the nitrogen source available in the medium. Addition of 0.25 mM NH4Cl to nitrate-grown cells promotes a clear short-term inactivation of glutamine synthetase, whose enzyme activity decreases to 5 to 10% of the initial value in 25 min. The intracellular levels of glutamine, determined under various conditions, taken together with the results obtained with azaserine (an inhibitor of transamidases...

  17. Gene Inactivation in the Cyanobacterium Synechococcus sp. PCC 7002 and the Green Sulfur Bacterium Chlorobium tepidum Using In Vitro-Made DNA Constructs and Natural Transformation

    DEFF Research Database (Denmark)

    Frigaard, Niels-Ulrik; Sakuragi, Yumiko; Bryant, Donald A

    2004-01-01

    Inactivation of a chromosomal gene is a useful approach to study the function of the gene in question and can be used to produce a desired phenotype in the organism. This chapter describes how to generate such mutants of the cyanobacterium Synechococcus sp. PCC 7002 and the green sulfur bacterium...... Chlorobium tepidum by natural transformation with synthetic DNA constructs. Two alternative methods to generate the DNA constructs, both performed entirely in vitro and based on the polymerase chain reaction (PCR), are also presented. These methods are ligation of DNA fragments with T4 DNA ligase...

  18. Transcription Profiling of the Model Cyanobacterium Synechococcus sp. Strain PCC 7002 by Next-Gen (SOLiD™) Sequencing of cDNA

    OpenAIRE

    Ludwig, Marcus; Bryant, Donald A.

    2011-01-01

    The genome of the unicellular, euryhaline cyanobacterium Synechococcus sp. PCC 7002 encodes about 3200 proteins. Transcripts were detected for nearly all annotated open reading frames by a global transcriptomic analysis by Next-Generation (SOLiD™) sequencing of cDNA. In the cDNA samples sequenced, ∼90% of the mapped sequences were derived from the 16S and 23S ribosomal RNAs and ∼10% of the sequences were derived from mRNAs. In cells grown photoautotrophically under standard conditions [38°C, ...

  19. Transcription profiling of the model cyanobacterium Synechococcus sp. strain PCC 7002 by NextGen (SOLiD™) Sequencing of cDNA

    OpenAIRE

    Marcus eLudwig; Bryant, Donald A.

    2011-01-01

    The genome of the unicellular, euryhaline cyanobacterium Synechococcus sp. PCC 7002 encodes about 3200 proteins. Transcripts were detected for nearly all annotated open reading frames by a global transcriptomic analysis by Next-Generation (SOLiDTM) sequencing of cDNA. In the cDNA samples sequenced, ~90% of the mapped sequences were derived from the 16S and 23S ribosomal RNAs and ~10% of the sequences were derived from mRNAs. In cells grown photoautotrophically under standard conditions (38 &#...

  20. Overexpression of SepJ alters septal morphology and heterocyst pattern regulated by diffusible signals in Anabaena.

    Science.gov (United States)

    Mariscal, Vicente; Nürnberg, Dennis J; Herrero, Antonia; Mullineaux, Conrad W; Flores, Enrique

    2016-09-01

    Filamentous, N2 -fixing, heterocyst-forming cyanobacteria grow as chains of cells that are connected by septal junctions. In the model organism Anabaena sp. strain PCC 7120, the septal protein SepJ is required for filament integrity, normal intercellular molecular exchange, heterocyst differentiation, and diazotrophic growth. An Anabaena strain overexpressing SepJ made wider septa between vegetative cells than the wild type, which correlated with a more spread location of SepJ in the septa as observed with a SepJ-GFP fusion, and contained an increased number of nanopores, the septal peptidoglycan perforations that likely accommodate septal junctions. The septa between heterocysts and vegetative cells, which are narrow in wild-type Anabaena, were notably enlarged in the SepJ-overexpressing mutant. Intercellular molecular exchange tested with fluorescent tracers was increased for the SepJ-overexpressing strain specifically in the case of calcein transfer between vegetative cells and heterocysts. These results support an association between calcein transfer, SepJ-related septal junctions, and septal peptidoglycan nanopores. Under nitrogen deprivation, the SepJ-overexpressing strain produced an increased number of contiguous heterocysts but a decreased percentage of total heterocysts. These effects were lost or altered in patS and hetN mutant backgrounds, supporting a role of SepJ in the intercellular transfer of regulatory signals for heterocyst differentiation.

  1. Inhibition of hydrogen uptake in Escherichia coli by expressing the hydrogenase from the cyanobacterium Synechocystis sp. PCC 6803

    Directory of Open Access Journals (Sweden)

    Wood Thomas K

    2007-05-01

    Full Text Available Abstract Background Molecular hydrogen is an environmentally-clean fuel and the reversible (bi-directional hydrogenase of the cyanobacterium Synechocystis sp. PCC 6803 as well as the native Escherichia coli hydrogenase 3 hold great promise for hydrogen generation. These enzymes perform the simple reaction 2H+ + 2e- ↔ H2 (g. Results Hydrogen yields were enhanced up to 41-fold by cloning the bidirectional hydrogenase (encoded by hoxEFUYH from the cyanobacterium into E. coli. Using an optimized medium, E. coli cells expressing hoxEFUYH also produced twice as much hydrogen as the well-studied Enterobacter aerogenes HU-101, and hydrogen gas bubbles are clearly visible from the cultures. Overexpression of HoxU alone (small diaphorase subunit accounts for 43% of the additional hydrogen produced by HoxEFUYH. In addition, hydrogen production in E. coli mutants with defects in the native formate hydrogenlyase system show that the cyanobacterial hydrogenase depends on both the native E. coli hydrogenase 3 as well as on its maturation proteins. Hydrogen absorption by cells expressing hoxEFUYH was up to 10 times lower than cells which lack the cloned cyanobacterial hydrogenase; hence, the enhanced hydrogen production in the presence of hoxEFUYH is due to inhibition of hydrogen uptake activity in E. coli. Hydrogen uptake by cells expressing hoxEFUYH was suppressed in three wild-type strains and in two hycE mutants but not in a double mutant defective in hydrogenase 1 and hydrogenase 2; hence, the active cyanobacterial locus suppresses hydrogen uptake by hydrogenase 1 and hydrogenase 2 but not by hydrogenase 3. Differential gene expression indicated that overexpression of HoxEFUYH does not alter expression of the native E. coli hydrogenase system; instead, biofilm-related genes are differentially regulated by expression of the cyanobacterial enzymes which resulted in 2-fold elevated biofilm formation. This appears to be the first enhanced hydrogen production

  2. The Acceptor Side of Photosystem II Is the Initial Target of Nitrite Stress in Synechocystis sp. Strain PCC 6803.

    Science.gov (United States)

    Zhang, Xin; Ma, Fei; Zhu, Xi; Zhu, Junying; Rong, Junfeng; Zhan, Jiao; Chen, Hui; He, Chenliu; Wang, Qiang

    2017-02-01

    Nitrite, a common form of inorganic nitrogen (N), can be used as a nitrogen source through N assimilation. However, high levels of nitrite depress photosynthesis in various organisms. In this study, we investigated which components of the photosynthetic electron transfer chain are targeted by nitrite stress in Synechocystis sp. strain PCC 6803 cells. Measurements of whole-chain and photosystem II (PSII)-mediated electron transport activities revealed that high levels of nitrite primarily impair electron flow in PSII. Changes in PSII activity in response to nitrite stress occurred in two distinct phases. During the first phase, which occurred in the first 3 h of nitrite treatment, electron transfer from the primary quinone acceptor (QA) to the secondary quinone acceptor (QB) was retarded, as indicated by chlorophyll (Chl) a fluorescence induction, S-state distribution, and QA(-) reoxidation tests. In the second phase, which occurred after 6 h of nitrite exposure, the reaction center was inactivated and the donor side of photosystem II was inhibited, as revealed by changes in Chl fluorescence parameters and thermoluminescence and by immunoblot analysis. Our data suggest that nitrite stress is highly damaging to PSII and disrupts PSII activity by a stepwise mechanism in which the acceptor side is the initial target. IMPORTANCE In our previous studies, an alga-based technology was proposed to fix the large amounts of nitrite that are released from NOX-rich flue gases and proved to be a promising industrial strategy for flue gas NOX bioremediation (W. Chen et al., Environ Sci Technol 50:1620-1627, 2016, https://doi.org/10.1021/acs.est.5b04696; X. Zhang et al., Environ Sci Technol 48:10497-10504, 2014, https://doi.org/10.1021/es5013824). However, the toxic effects of high concentrations of nitrite on algal cells remain obscure. The analysis of growth rates, photochemistry, and protein profiles in our study provides important evidence that the inhibition by nitrite occurs

  3. Metabolic Flux Analysis of the Synechocystis sp. PCC 6803 ΔnrtABCD Mutant Reveals a Mechanism for Metabolic Adaptation to Nitrogen-Limited Conditions.

    Science.gov (United States)

    Nakajima, Tsubasa; Yoshikawa, Katsunori; Toya, Yoshihiro; Matsuda, Fumio; Shimizu, Hiroshi

    2017-03-01

    Metabolic flux redirection during nitrogen-limited growth was investigated in the Synechocystis sp. PCC 6803 glucose-tolerant (GT) strain under photoautotrophic conditions by isotopically non-stationary metabolic flux analysis (INST-MFA). A ΔnrtABCD mutant of Synechocystis sp. PCC 6803 was constructed to reproduce phenotypes arising during nitrogen starvation. The ΔnrtABCD mutant and the wild-type GT strain were cultured under photoautotrophic conditions by a photobioreactor. Intracellular metabolites were labeled over a time course using NaH13CO3 as a carbon source. Based on these data, the metabolic flux distributions in the wild-type and ΔnrtABCD cells were estimated by INST-MFA. The wild-type GT and ΔnrtABCD strains displayed similar distribution patterns, although the absolute levels of metabolic flux were lower in ΔnrtABCD. Furthermore, the relative flux levels for glycogen metabolism, anaplerotic reactions and the oxidative pentose phosphate pathway were increased in ΔnrtABCD. This was probably due to the increased expression of enzyme genes that respond to nitrogen depletion. Additionally, we found that the ratio of ATP/NADPH demand increased slightly in the ΔnrtABCD mutant. These results indicated that futile ATP consumption increases under nitrogen-limited conditions because the Calvin-Benson cycle and the oxidative pentose phosphate pathway form a metabolic futile cycle that consumes ATP without CO2 fixation and NADPH regeneration.

  4. Integrated in silico Analyses of Regulatory and Metabolic Networks of Synechococcus sp. PCC 7002 Reveal Relationships between Gene Centrality and Essentiality

    Directory of Open Access Journals (Sweden)

    Hyun-Seob Song

    2015-03-01

    Full Text Available Cyanobacteria dynamically relay environmental inputs to intracellular adaptations through a coordinated adjustment of photosynthetic efficiency and carbon processing rates. The output of such adaptations is reflected through changes in transcriptional patterns and metabolic flux distributions that ultimately define growth strategy. To address interrelationships between metabolism and regulation, we performed integrative analyses of metabolic and gene co-expression networks in a model cyanobacterium, Synechococcus sp. PCC 7002. Centrality analyses using the gene co-expression network identified a set of key genes, which were defined here as “topologically important.” Parallel in silico gene knock-out simulations, using the genome-scale metabolic network, classified what we termed as “functionally important” genes, deletion of which affected growth or metabolism. A strong positive correlation was observed between topologically and functionally important genes. Functionally important genes exhibited variable levels of topological centrality; however, the majority of topologically central genes were found to be functionally essential for growth. Subsequent functional enrichment analysis revealed that both functionally and topologically important genes in Synechococcus sp. PCC 7002 are predominantly associated with translation and energy metabolism, two cellular processes critical for growth. This research demonstrates how synergistic network-level analyses can be used for reconciliation of metabolic and gene expression data to uncover fundamental biological principles.

  5. Sll0528, a Site-2-Protease, Is Critically Involved in Cold, Salt and Hyperosmotic Stress Acclimation of Cyanobacterium Synechocystis sp. PCC 6803

    Directory of Open Access Journals (Sweden)

    Haijin Lei

    2014-12-01

    Full Text Available Site-2-proteases (S2Ps mediated proteolysis of transmembrane transcriptional regulators is a conserved mechanism to regulate transmembrane signaling. The universal presence of S2P homologs in different cyanobacterial genomes suggest conserved and fundamental functions, though limited data has been available. Here we provide the first evidence that Sll0528, a site-2-protease in Synechocystis sp. PCC 6803 is crucial for salt, cold and hyperosmotic stress acclimation. Remarkable induction of sll0528 gene expression was observed under salt, cold and hyperosmotic stress, much higher than induction of the other three S2Ps. Knock-out of sll0528 gene in wild type Synechocystis sp. PCC 6803 increased their sensitivity to salt, cold and hyperosmotic stress, as revealed by retarded growth, reduced pigments and disrupted photosystems. The sll0528 gene was induced to a much smaller extent by high light and mixotrophic growth with glucose. Similar growth responses of the sll0528 knockout mutant and wild type under high light and mixotrophic growth indicated that sll0528 was dispensable for these conditions. Recombinant Sll0528 protein could cleave beta-casein into smaller fragments. These results together suggest that the Sll0528 metalloprotease plays a role in the stress response and lays the foundation for further investigation of its mechanism, as well as providing hints for the functional analysis of other S2Ps in cyanobacteria.

  6. The highly abundant chlorophyll-protein complex of iron-deficient Synechococcus sp. PCC7942 (CP43') is encoded by the isiA gene.

    Science.gov (United States)

    Burnap, R L; Troyan, T; Sherman, L A

    1993-11-01

    A chlorophyll (Chl)-protein complex designated CPVI-4 becomes the major pigment-protein complex in Synechococcus sp. PCC7942 cells grown under conditions of iron limitation. Work by Laudenbach et al. (J Bacteriol [1988] 170: 5018-5026) has identified an iron-repressible operon, designated isiAB, containing the flavodoxin gene and a gene predicted to encode a Chl-binding protein resembling CP43 of photosystem II. To test the hypothesis that the CP43-like protein is a component of the CPVI-4 complex, we have inactivated the isiAB operon in Synechococcus sp. PCC7942 using directed insertional mutagenesis. Mutant cells grown under conditions of iron limitation exhibit pronounced changes in their spectroscopic and photosynthetic properties relative to similarly grown wild-type cells. Notably, the strong 77 K fluorescence emission at 685 nm, which dominates the spectrum of iron-deficient wild-type cells, is dramatically reduced in the mutant. The loss of this emission appears to unmask the otherwise obscured photosystem II emissions at 685 and 695 nm. Most importantly, mildly denaturing gel electrophoresis shows that mutant cells no longer express the CPVI-4 complex, indicating that the isiA gene encodes a component of this abundant Chl-protein complex.

  7. An alternative methionine aminopeptidase, MAP-A, is required for nitrogen starvation and high-light acclimation in the cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Drath, Miriam; Baier, Kerstin; Forchhammer, Karl

    2009-05-01

    Methionine aminopeptidases (MetAPs or MAPs, encoded by map genes) are ubiquitous and pivotal enzymes for protein maturation in all living organisms. Whereas most bacteria harbour only one map gene, many cyanobacterial genomes contain two map paralogues, the genome of Synechocystis sp. PCC 6803 even three. The physiological function of multiple map paralogues remains elusive so far. This communication reports for the first time differential MetAP function in a cyanobacterium. In Synechocystis sp. PCC 6803, the universally conserved mapC gene (sll0555) is predominantly expressed in exponentially growing cells and appears to be a housekeeping gene. By contrast, expression of mapA (slr0918) and mapB (slr0786) genes increases during stress conditions. The mapB paralogue is only transiently expressed, whereas the widely distributed mapA gene appears to be the major MetAP during stress conditions. A mapA-deficient Synechocystis mutant shows a subtle impairment of photosystem II properties even under non-stressed conditions. In particular, the binding site for the quinone Q(B) is affected, indicating specific N-terminal methionine processing requirements of photosystem II components. MAP-A-specific processing becomes essential under certain stress conditions, since the mapA-deficient mutant is severely impaired in surviving conditions of prolonged nitrogen starvation and high light exposure.

  8. ApcD is required for state transition but not involved in blue-light induced quenching in the cyanobacterium Anabaena sp. PCC7120

    Institute of Scientific and Technical Information of China (English)

    DONG ChunXia; ZHAO JinDong

    2008-01-01

    Pbycobilisomes (PBS) are able to transfer absorbed energy to photosystem Ⅰ and Ⅱ, and the distribution of light energy between two photosystems is regulated by state transitions. In this study we show that energy transfer from PBS to photosystem Ⅰ (PSI) requires ApcD. Cells were unable to perform state transitions in the absence of ApcD. The apcD mutant grows more slowly in light mainly absorbed by PBS, indicating that ApcD-dependent energy transfer to PSI is required for optimal growth under this condition. The apoD mutant showed normal blue-light induced quenching, suggesting that ApcD is not required for this process and state transitions are independent of blue-light induced quenching. Under nitrogen fixing condition, the growth rates of the wild type and the mutant were the same, indicating that energy transfer from PBS to PSI in heterocysta was not required for nitrogen fixation.

  9. Inactivation of agmatinase expressed in vegetative cells alters arginine catabolism and prevents diazotrophic growth in the heterocyst-forming cyanobacterium Anabaena.

    Science.gov (United States)

    Burnat, Mireia; Flores, Enrique

    2014-10-01

    Arginine decarboxylase produces agmatine, and arginase and agmatinase are ureohydrolases that catalyze the production of ornithine and putrescine from arginine and agmatine, respectively, releasing urea. In the genome of the filamentous, heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120, ORF alr2310 putatively encodes an ureohydrolase. Cells of Anabaena supplemented with [(14) C]arginine took up and catabolized this amino acid generating a set of labeled amino acids that included ornithine, proline, and glutamate. In an alr2310 deletion mutant, an agmatine spot appeared and labeled glutamate increased with respect to the wild type, suggesting that Alr2310 is an agmatinase rather than an arginase. As determined in cell-free extracts, agmatinase activity could be detected in the wild type but not in the mutant. Thus, alr2310 is the Anabaena speB gene encoding agmatinase. The ∆alr2310 mutant accumulated large amounts of cyanophycin granule polypeptide, lacked nitrogenase activity, and did not grow diazotrophically. Growth tests in solid media showed that agmatine is inhibitory for Anabaena, especially under diazotrophic conditions, suggesting that growth of the mutant is inhibited by non-metabolized agmatine. Measurements of incorporation of radioactivity from [(14) C]leucine into macromolecules showed, however, a limited inhibition of protein synthesis in the ∆alr2310 mutant. Analysis of an Anabaena strain producing an Alr2310-GFP (green fluorescent protein) fusion showed expression in vegetative cells but much less in heterocysts, implying compartmentalization of the arginine decarboxylation pathway in the diazotrophic filaments of this heterocyst-forming cyanobacterium.

  10. Proteome Analyses of Strains ATCC 51142 and PCC 7822 of the Diazotrophic Cyanobacterium Cyanothece sp. under Culture Conditions Resulting in Enhanced H2 Production

    Science.gov (United States)

    Aryal, Uma K.; Callister, Stephen J.; Mishra, Sujata; Zhang, Xiaohui; Shutthanandan, Janani I.; Angel, Thomas E.; Shukla, Anil K.; Monroe, Matthew E.; Moore, Ronald J.; Koppenaal, David W.; Smith, Richard D.

    2013-01-01

    Cultures of the cyanobacterial genus Cyanothece have been shown to produce high levels of biohydrogen. These strains are diazotrophic and undergo pronounced diurnal cycles when grown under N2-fixing conditions in light-dark cycles. We seek to better understand the way in which proteins respond to these diurnal changes, and we performed quantitative proteome analysis of Cyanothece sp. strains ATCC 51142 and PCC 7822 grown under 8 different nutritional conditions. Nitrogenase expression was limited to N2-fixing conditions, and in the absence of glycerol, nitrogenase gene expression was linked to the dark period. However, glycerol induced expression of nitrogenase during part of the light period, together with cytochrome c oxidase (Cox), glycogen phosphorylase (Glp), and glycolytic and pentose phosphate pathway (PPP) enzymes. This indicated that nitrogenase expression in the light was facilitated via higher levels of respiration and glycogen breakdown. Key enzymes of the Calvin cycle were inhibited in Cyanothece ATCC 51142 in the presence of glycerol under H2-producing conditions, suggesting a competition between these sources of carbon. However, in Cyanothece PCC 7822, the Calvin cycle still played a role in cofactor recycling during H2 production. Our data comprise the first comprehensive profiling of proteome changes in Cyanothece PCC 7822 and allow an in-depth comparative analysis of major physiological and biochemical processes that influence H2 production in both strains. Our results revealed many previously uncharacterized proteins that may play a role in nitrogenase activity and in other metabolic pathways and may provide suitable targets for genetic manipulation that would lead to improvement of large-scale H2 production. PMID:23204418

  11. Promoter recognition by a cyanobacterial RNA polymerase: in vitro studies with the Calothrix sp. PCC 7601 transcriptional factors RcaA and RcaD.

    Science.gov (United States)

    Schyns, G; Jia, L; Coursin, T; Tandeau de Marsac, N; Houmard, J

    1998-03-01

    To study the transcriptional apparatus and the mechanisms that control gene expression in cyanobacteria, the RNA polymerase was purified from the filamentous Calothrix sp. PCC 7601 and used in in vitro transcription assays. Conditions required for specific transcription initiation to occur were analyzed with the eleven Calothrix PCC 7601 genes for which the 5' ends have been mapped. Most of the transcripts directly obtained did not have the expected size, providing a test for looking at specific transcription factors. Addition of RcaA, a protein that binds to the promoter region of the phycobiliprotein cpeBA operon, restored accurate initiation of transcription in the in vitro system for three phycobiliprotein promoters. RcaA thus is a transcription factor that allows to mimick in vivo transcription. In parallel, the functional properties of the Escherichia coli and cyanobacterial RNA polymerases were compared. The enteric enzyme could not precisely initiate transcription at the promoter of a phycobiliprotein gene and, reciprocally, the cyanobacterial RNA polymerase could initiate transcription at PlacUV5, but not from wild-type Plac promoters. The different behaviours of the enzymes are discussed in the light of the structural differences that exist between subunits of the RNA polymerases.

  12. GroEL of the nitrogen-fixing cyanobacterium Anabaena sp. strain L-31 exhibits GroES and ATP-independent refolding activity.

    Science.gov (United States)

    Potnis, Akhilesh A; Rajaram, Hema; Apte, Shree K

    2016-03-01

    The nitrogen-fixing cyanobacterium, Anabaena L-31 has two Hsp60 proteins, 59 kDa GroEL coded by the second gene of groESL operon and 61 kDa Cpn60 coded by cpn60 gene. Anabaena GroEL formed stable higher oligomer (>12-mer) in the presence of K(+) and prevented thermal aggregation of malate dehydrogenase (MDH). Using three protein substrates (MDH, All1541 and green fluorescent protein), it was found that the refolding activity of Anabaena GroEL was lower than that of Escherichia coli GroEL, but independent of both GroES and ATP. This correlated with in vivo data. GroEL exhibited ATPase activity which was enhanced in the presence of GroES and absence of a denatured protein, contrary to that observed for bacterial GroEL. However, a significant role for ATP could not be ascertained during in vitro folding assays. The monomeric Cpn60 exhibited much lower refolding activity than GroEL, unaffected by GroES and ATP. In vitro studies revealed inhibition of the refolding activity of Anabaena GroEL by Cpn60, which could be due to their different oligomeric status. The role of GroES and ATP may have been added during the course of evolution from the ancient cyanobacteria to modern day bacteria enhancing the refolding ability and ensuring wider scope of substrates for GroEL.

  13. A quantitative evaluation of ethylene production in the recombinant cyanobacterium Synechocystis sp. PCC 6803 harboring the ethylene-forming enzyme by membrane inlet mass spectrometry.

    Science.gov (United States)

    Zavřel, Tomáš; Knoop, Henning; Steuer, Ralf; Jones, Patrik R; Červený, Jan; Trtílek, Martin

    2016-02-01

    The prediction of the world's future energy consumption and global climate change makes it desirable to identify new technologies to replace or augment fossil fuels by environmentally sustainable alternatives. One appealing sustainable energy concept is harvesting solar energy via photosynthesis coupled to conversion of CO2 into chemical feedstock and fuel. In this work, the production of ethylene, the most widely used petrochemical produced exclusively from fossil fuels, in the model cyanobacterium Synechocystis sp. PCC 6803 is studied. A novel instrumentation setup for quantitative monitoring of ethylene production using a combination of flat-panel photobioreactor coupled to a membrane-inlet mass spectrometer is introduced. Carbon partitioning is estimated using a quantitative model of cyanobacterial metabolism. The results show that ethylene is produced under a wide range of light intensities with an optimum at modest irradiances. The results allow production conditions to be optimized in a highly controlled setup.

  14. Biochemical examination of the potential eukaryotic-type protein kinase genes in the complete genome of the unicellular Cyanobacterium synechocystis sp. PCC 6803.

    Science.gov (United States)

    Kamei, Ayako; Yuasa, Takashi; Geng, Xiaoxing; Ikeuchi, Masahiko

    2002-06-30

    The complete genome of the unicellular motile cyanobacterium Synechocystis sp. PCC 6803 harbors seven putative genes for a subfamily Pkn2 of the eukaryotic-type (or "Hanks-type") protein kinase. Previously, SpkA and SpkB were shown to have protein kinase activity and to be required for cell motility. Here, the other five genes were examined. These genes, except for spkG (slr0152), were successfully expressed in Escherichia coli. Eukaryotic-type protein kinase activity of the expressed SpkC (Slr0599), SpkD (S110776) and SpkF (Slr1225) was demonstrated as autophosphorylation and phosphorylation of the general substrate proteins. SpkE (Slr1443) did not show any activity, a finding consistent with its lack of several key amino acid residues in its kinase motif. Gene-disrupted mutants showed no discernible defect in phenotype except that spkD was apparently essential for survival.

  15. Degradation of phycobilisomes in Synechocystis sp. PCC6803: evidence for essential formation of an NblA1/NblA2 heterodimer and its codegradation by A Clp protease complex.

    Science.gov (United States)

    Baier, Antje; Winkler, Wiebke; Korte, Thomas; Lockau, Wolfgang; Karradt, Anne

    2014-04-25

    When cyanobacteria acclimate to nitrogen deficiency, they degrade their large (3-5-MDa), light-harvesting complexes, the phycobilisomes. This massive, yet specific, intracellular degradation of the pigmented phycobiliproteins causes a color change of cyanobacterial cultures from blue-green to yellow-green, a process referred to as chlorosis or bleaching. Phycobilisome degradation is induced by expression of the nblA gene, which encodes a protein of ~7 kDa. NblA most likely acts as an adaptor protein that guides a Clp protease to the phycobiliproteins, thereby initiating the degradation process. Most cyanobacteria and red algae possess just one nblA-homologous gene. As an exception, the widely used "model organism" Synechocystis sp. PCC6803 expresses two such genes, nblA16803 and nblA26803, both of whose products are required for phycobilisome degradation. Here, we demonstrate that the two NblA proteins heterodimerize in vitro and in vivo using pull-down assays and a Förster energy-transfer approach, respectively. We further show that the NblA proteins form a ternary complex with ClpC (the HSP100 chaperone partner of Clp proteases) and phycobiliproteins in vitro. This complex is susceptible to ATP-dependent degradation by a Clp protease, a finding that supports a proposed mechanism of the degradation process. Expression of the single nblA gene encoded by the genome of the N2-fixing, filamentous cyanobacterium Nostoc sp. PCC7120 in the nblA1/nblA2 mutant of Synechocystis sp. PCC6803 induced phycobilisome degradation, suggesting that the function of the NblA heterodimer of Synechocystis sp. PCC6803 is combined in the homodimeric protein of Nostoc sp. PCC7120.

  16. Optimization of pH and nitrogen for enhanced hydrogen production by Synechocystis sp. PCC 6803 via statistical and machine learning methods.

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    Burrows, Elizabeth H; Wong, Weng-Keen; Fern, Xiaoli; Chaplen, Frank W R; Ely, Roger L

    2009-01-01

    The nitrogen (N) concentration and pH of culture media were optimized for increased fermentative hydrogen (H(2)) production from the cyanobacterium, Synechocystis sp. PCC 6803. The optimization was conducted using two procedures, response surface methodology (RSM), which is commonly used, and a memory-based machine learning algorithm, Q2, which has not been used previously in biotechnology applications. Both RSM and Q2 were successful in predicting optimum conditions that yielded higher H(2) than the media reported by Burrows et al., Int J Hydrogen Energy. 2008;33:6092-6099 optimized for N, S, and C (called EHB-1 media hereafter), which itself yielded almost 150 times more H(2) than Synechocystis sp. PCC 6803 grown on sulfur-free BG-11 media. RSM predicted an optimum N concentration of 0.63 mM and pH of 7.77, which yielded 1.70 times more H(2) than EHB-1 media when normalized to chlorophyll concentration (0.68 +/- 0.43 micromol H(2) mg Chl(-1) h(-1)) and 1.35 times more when normalized to optical density (1.62 +/- 0.09 nmol H(2) OD(730) (-1) h(-1)). Q2 predicted an optimum of 0.36 mM N and pH of 7.88, which yielded 1.94 and 1.27 times more H(2) than EHB-1 media when normalized to chlorophyll concentration (0.77 +/- 0.44 micromol H(2) mg Chl(-1) h(-1)) and optical density (1.53 +/- 0.07 nmol H(2) OD(730) (-1) h(-1)), respectively. Both optimization methods have unique benefits and drawbacks that are identified and discussed in this study.

  17. The Cyanobacterial Ribosomal-Associated Protein LrtA Is Involved in Post-Stress Survival in Synechocystis sp. PCC 6803.

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    Carla V Galmozzi

    Full Text Available A light-repressed transcript encodes the LrtA protein in cyanobacteria. We show that half-life of lrtA transcript from Synechocystis sp. PCC 6803 is higher in dark-treated cells as compared to light-grown cells, suggesting post-transcriptional control of lrtA expression. The lrtA 5´ untranslated leader region is involved in that darkness-dependent regulation. We also found that Synechocystis sp. PCC 6803 LrtA is a ribosome-associated protein present in both 30S and 70S ribosomal particles. In order to investigate the function of this protein we have constructed a deletion mutant of the lrtA gene. Cells lacking LrtA (∆lrtA had significantly lower amount of 70S particles and a greater amount of 30S and 50S particles, suggesting a role of LrtA in stabilizing 70S particles. Synechocystis strains with different amounts of LrtA protein: wild-type, ∆lrtA, and LrtAS (overexpressing lrtA showed no differences in their growth rate under standard laboratory conditions. However, a clear LrtA dose-dependent effect was observed in the presence of the antibiotic tylosin, being the LrtAS strains the most sensitive. Similar results were obtained under hyperosmotic stress caused by sorbitol. Conversely, after prolonged periods of starvation, ∆lrtA strains were delayed in their growth with respect to the wild-type and the LrtAS strains. A positive role of LrtA protein in post-stress survival is proposed.

  18. The Cyanobacterial Ribosomal-Associated Protein LrtA Is Involved in Post-Stress Survival in Synechocystis sp. PCC 6803

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    Galmozzi, Carla V.; Florencio, Francisco J.; Muro-Pastor, M. Isabel

    2016-01-01

    A light-repressed transcript encodes the LrtA protein in cyanobacteria. We show that half-life of lrtA transcript from Synechocystis sp. PCC 6803 is higher in dark-treated cells as compared to light-grown cells, suggesting post-transcriptional control of lrtA expression. The lrtA 5´ untranslated leader region is involved in that darkness-dependent regulation. We also found that Synechocystis sp. PCC 6803 LrtA is a ribosome-associated protein present in both 30S and 70S ribosomal particles. In order to investigate the function of this protein we have constructed a deletion mutant of the lrtA gene. Cells lacking LrtA (∆lrtA) had significantly lower amount of 70S particles and a greater amount of 30S and 50S particles, suggesting a role of LrtA in stabilizing 70S particles. Synechocystis strains with different amounts of LrtA protein: wild-type, ∆lrtA, and LrtAS (overexpressing lrtA) showed no differences in their growth rate under standard laboratory conditions. However, a clear LrtA dose-dependent effect was observed in the presence of the antibiotic tylosin, being the LrtAS strains the most sensitive. Similar results were obtained under hyperosmotic stress caused by sorbitol. Conversely, after prolonged periods of starvation, ∆lrtA strains were delayed in their growth with respect to the wild-type and the LrtAS strains. A positive role of LrtA protein in post-stress survival is proposed. PMID:27442126

  19. Modulation of Medium-Chain Fatty Acid Synthesis in Synechococcus sp. PCC 7002 by Replacing FabH with a Chaetoceros ketoacyl-ACP synthase

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    Huiya eGu

    2016-05-01

    Full Text Available The isolation or engineering of algal cells synthesizing high levels of medium-chain fatty acids (MCFAs is attractive to mitigate the high clouding point of longer chain fatty acids in algal based biodiesel. To develop a more informed understanding of MCFA synthesis is photosynthetic microorganisms, we isolated several algae from Great Salt Lake and screened this collection for MCFA accumulation to identify strains naturally accumulating high levels of MCFA. A diatom, Chaetoceros sp. GSL56, accumulated particularly high levels of C14 (up to 40%, with the majority of C14 fatty acids (~2/3 allocated in triacylglycerols. Using whole cell transcriptome sequencing and de novo assembly, putative genes encoding fatty acid synthesis enzymes were identified. Enzymes from this Chaetoceros sp. were expressed in the cyanobacterium Synechococcus sp. PCC 7002 to validate gene function and to determine whether eukaryotic enzymes lacking bacteria evolutionary control mechanisms could be used to improve MCFA production in this promising production strains. Replacement of the Synechococcus 7002 native FabH with a Chaetoceros ketoacyl-ACP synthase III increased MCFA synthesis up to five fold. The level of increase is dependent on promoter strength and culturing conditions.

  20. Modulation of fatty acids and hydrocarbons in Anabaena 7120 and its ntcA mutant under calcium.

    Science.gov (United States)

    Singh, Savita; Verma, Ekta; Tiwari, Balkrishna; Niveshika; Mishra, Arun Kumar

    2017-02-01

    Calcium being a signaling molecule and mediator of cell response, we examined the modulation in fatty acid and hydrocarbon profiles of wild type cyanobacterium Anabaena sp. PCC 7120 and its ntcA mutant under the influence of different calcium chloride concentrations (0-10 mM). Dynamic modifications in fatty acid and hydrocarbon profile were evident through GC-FID analysis of extracted lipids. In the wild type, increase in CaCl2 (10 mM) resulted in unsaturation of fatty acids (observed in terms of high MUFA/PUFA ratio) while hydrocarbon production was distinctly high in the mutant strain compared to wild type at all tested concentrations. The synthesis of short chain hydrocarbons (C5-C8) were dominated at inhibitory concentration (10 mM CaCl2) in mutant strain. Results suggest that the increase in MUFA/PUFA ratio at inhibitory concentration in wild type, and higher percentage of hydrocarbons in mutant strain, may be attributed to the survival and acclimation strategies under altered calcium environment. Our results also suggest the involvement of the ntcA gene (master regulator of N2 metabolism) in regulation of carbon metabolism; specifically fatty acid, hydrocarbon, and other metabolic compounds essential for maintenance and sustenance of growth under stress condition. Thus, our study outlines basic acclimation response along with possibilities of production of fatty acid and hydrocarbon derived biofuel and other bioactive compounds in Anabaena sp. PCC 7120 under altered calcium levels which could be of biotechnological interest.

  1. Photosynthetic Versatility in the Genome of Geitlerinema sp. PCC 9228 (Formerly Oscillatoria limnetica ‘Solar Lake’), a Model Anoxygenic Photosynthetic Cyanobacterium

    Science.gov (United States)

    Grim, Sharon L.; Dick, Gregory J.

    2016-01-01

    Anoxygenic cyanobacteria that use sulfide as the electron donor for photosynthesis are a potentially influential but poorly constrained force on Earth’s biogeochemistry. Their versatile metabolism may have boosted primary production and nitrogen cycling in euxinic coastal margins in the Proterozoic. In addition, they represent a biological mechanism for limiting the accumulation of atmospheric oxygen, especially before the Great Oxidation Event and in the low-oxygen conditions of the Proterozoic. In this study, we describe the draft genome sequence of Geitlerinema sp. PCC 9228, formerly Oscillatoria limnetica ‘Solar Lake’, a mat-forming diazotrophic cyanobacterium that can switch between oxygenic photosynthesis and sulfide-based anoxygenic photosynthesis (AP). Geitlerinema possesses three variants of psbA, which encodes protein D1, a core component of the photosystem II reaction center. Phylogenetic analyses indicate that one variant is closely affiliated with cyanobacterial psbA genes that code for a D1 protein used for oxygen-sensitive processes. Another version is phylogenetically similar to cyanobacterial psbA genes that encode D1 proteins used under microaerobic conditions, and the third variant may be cued to high light and/or elevated oxygen concentrations. Geitlerinema has the canonical gene for sulfide quinone reductase (SQR) used in cyanobacterial AP and a putative transcriptional regulatory gene in the same operon. Another operon with a second, distinct sqr and regulatory gene is present, and is phylogenetically related to sqr genes used for high sulfide concentrations. The genome has a comprehensive nif gene suite for nitrogen fixation, supporting previous observations of nitrogenase activity. Geitlerinema possesses a bidirectional hydrogenase rather than the uptake hydrogenase typically used by cyanobacteria in diazotrophy. Overall, the genome sequence of Geitlerinema sp. PCC 9228 highlights potential cyanobacterial strategies to cope with

  2. Photosynthetic versatility in the genome of Geitlerinema sp. PCC 9228 (formerly Oscillatoria limnetica ‘Solar Lake’, a model anoxygenic photosynthetic cyanobacterium

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    Sharon L Grim

    2016-10-01

    Full Text Available Anoxygenic cyanobacteria that use sulfide as the electron donor for photosynthesis are a potentially influential but poorly constrained force on Earth’s biogeochemistry. Their versatile metabolism may have boosted primary production and nitrogen cycling in euxinic coastal margins in the Proterozoic. In addition, they represent a biological mechanism for limiting the accumulation of atmospheric oxygen, especially before the Great Oxidation Event and in the low-oxygen conditions of the Proterozoic. In this study, we describe the draft genome sequence of Geitlerinema sp. PCC 9228, formerly Oscillatoria limnetica ‘Solar Lake’, a mat-forming diazotrophic cyanobacterium that can switch between oxygenic photosynthesis and sulfide-based anoxygenic photosynthesis. Geitlerinema possesses three variants of psbA, which encodes protein D1, a core component of the photosystem II reaction center. Phylogenetic analyses indicate that one variant is closely affiliated with cyanobacterial psbA genes that code for a D1 protein used for oxygen-sensitive processes. Another version is phylogenetically similar to cyanobacterial psbA genes that encode D1 proteins used under microaerobic conditions, and the third variant may be cued to high light and/or elevated oxygen concentrations. Geitlerinema has the canonical gene for sulfide quinone reductase (SQR used in cyanobacterial anoxygenic photosynthesis and a putative transcriptional regulatory gene in the same operon. Another operon with a second, distinct sqr and regulatory gene is present, and is phylogenetically related to sqr genes used for high sulfide concentrations. The genome has a comprehensive nif gene suite for nitrogen fixation, supporting previous observations of nitrogenase activity. Geitlerinema possesses a bidirectional hydrogenase rather than the uptake hydrogenase typically used by cyanobacteria in diazotrophy. Overall, the genome sequence of Geitlerinema sp. PCC 9228 highlights potential

  3. Culturing Synechocystis sp. Strain PCC 6803 with N2 and CO2 in a Diel Regime Reveals Multiphase Glycogen Dynamics with Low Maintenance Costs

    Science.gov (United States)

    Angermayr, S. Andreas; van Alphen, Pascal; Hasdemir, Dicle; Kramer, Gertjan; Iqbal, Muzamal; van Grondelle, Wilmar; Hoefsloot, Huub C.; Choi, Young Hae

    2016-01-01

    ABSTRACT Investigating the physiology of cyanobacteria cultured under a diel light regime is relevant for a better understanding of the resulting growth characteristics and for specific biotechnological applications that are foreseen for these photosynthetic organisms. Here, we present the results of a multiomics study of the model cyanobacterium Synechocystis sp. strain PCC 6803, cultured in a lab-scale photobioreactor in physiological conditions relevant for large-scale culturing. The culture was sparged with N2 and CO2, leading to an anoxic environment during the dark period. Growth followed the availability of light. Metabolite analysis performed with 1H nuclear magnetic resonance analysis showed that amino acids involved in nitrogen and sulfur assimilation showed elevated levels in the light. Most protein levels, analyzed through mass spectrometry, remained rather stable. However, several high-light-response proteins and stress-response proteins showed distinct changes at the onset of the light period. Microarray-based transcript analysis found common patterns of ∼56% of the transcriptome following the diel regime. These oscillating transcripts could be grouped coarsely into genes that were upregulated and downregulated in the dark period. The accumulated glycogen was degraded in the anaerobic environment in the dark. A small part was degraded gradually, reflecting basic maintenance requirements of the cells in darkness. Surprisingly, the largest part was degraded rapidly in a short time span at the end of the dark period. This degradation could allow rapid formation of metabolic intermediates at the end of the dark period, preparing the cells for the resumption of growth at the start of the light period. IMPORTANCE Industrial-scale biotechnological applications are anticipated for cyanobacteria. We simulated large-scale high-cell-density culturing of Synechocystis sp. PCC 6803 under a diel light regime in a lab-scale photobioreactor. In BG-11 medium

  4. Divisome-dependent subcellular localization of cell-cell joining protein SepJ in the filamentous cyanobacterium Anabaena.

    Science.gov (United States)

    Ramos-León, Félix; Mariscal, Vicente; Frías, José E; Flores, Enrique; Herrero, Antonia

    2015-05-01

    Heterocyst-forming cyanobacteria are multicellular organisms that grow as filaments that can be hundreds of cells long. Septal junction complexes, of which SepJ is a possible component, appear to join the cells in the filament. SepJ is a cytoplasmic membrane protein that contains a long predicted periplasmic section and localizes not only to the cell poles in the intercellular septa but also to a position similar to a Z ring when cell division starts suggesting a relation with the divisome. Here, we created a mutant of Anabaena sp. strain PCC 7120 in which the essential divisome gene ftsZ is expressed from a synthetic NtcA-dependent promoter, whose activity depends on the nitrogen source. In the presence of ammonium, low levels of FtsZ were produced, and the subcellular localization of SepJ, which was investigated by immunofluorescence, was impaired. Possible interactions of SepJ with itself and with divisome proteins FtsZ, FtsQ and FtsW were investigated using the bacterial two-hybrid system. We found SepJ self-interaction and a specific interaction with FtsQ, confirmed by co-purification and involving parts of the SepJ and FtsQ periplasmic sections. Therefore, SepJ can form multimers, and in Anabaena, the divisome has a role beyond cell division, localizing a septal protein essential for multicellularity.

  5. RNA-seq based identification and mutant validation of gene targets related to ethanol resistance in cyanobacterial Synechocystis sp. PCC 6803

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    Wang Jiangxin

    2012-12-01

    Full Text Available Abstract Background Fermentation production of biofuel ethanol consumes agricultural crops, which will compete directly with the food supply. As an alternative, photosynthetic cyanobacteria have been proposed as microbial factories to produce ethanol directly from solar energy and CO2. However, the ethanol productivity from photoautotrophic cyanobacteria is still very low, mostly due to the low tolerance of cyanobacterial systems to ethanol stress. Results To build a foundation necessary to engineer robust ethanol-producing cyanobacterial hosts, in this study we applied a quantitative transcriptomics approach with a next-generation sequencing technology, combined with quantitative reverse-transcript PCR (RT-PCR analysis, to reveal the global metabolic responses to ethanol in model cyanobacterial Synechocystis sp. PCC 6803. The results showed that ethanol exposure induced genes involved in common stress responses, transporting and cell envelope modification. In addition, the cells can also utilize enhanced polyhydroxyalkanoates (PHA accumulation and glyoxalase detoxication pathway as means against ethanol stress. The up-regulation of photosynthesis by ethanol was also further confirmed at transcriptional level. Finally, we used gene knockout strains to validate the potential target genes related to ethanol tolerance. Conclusion RNA-Seq based global transcriptomic analysis provided a comprehensive view of cellular response to ethanol exposure. The analysis provided a list of gene targets for engineering ethanol tolerance in cyanobacterium Synechocystis.

  6. Pleiotropic effect of sigE over-expression on cell morphology, photosynthesis and hydrogen production in Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Osanai, Takashi; Kuwahara, Ayuko; Iijima, Hiroko; Toyooka, Kiminori; Sato, Mayuko; Tanaka, Kan; Ikeuchi, Masahiko; Saito, Kazuki; Hirai, Masami Yokota

    2013-11-01

    Over-expression of sigE, a gene encoding an RNA polymerase sigma factor in the unicellular cyanobacterium Synechocystis sp. PCC 6803, is known to activate sugar catabolism and bioplastic production. In this study, we investigated the effects of sigE over-expression on cell morphology, photosynthesis and hydrogen production in this cyanobacterium. Transmission electron and scanning probe microscopic analyses revealed that sigE over-expression increased the cell size, possibly as a result of aberrant cell division. Over-expression of sigE reduced respiration and photosynthesis activities via changes in gene expression and chlorophyll fluorescence. Hydrogen production under micro-oxic conditions is enhanced in sigE over-expressing cells. Despite these pleiotropic phenotypes, the sigE over-expressing strain showed normal cell viability under both nitrogen-replete and nitrogen-depleted conditions. These results provide insights into the inter-relationship among metabolism, cell morphology, photosynthesis and hydrogen production in this unicellular cyanobacterium.

  7. Biochemical and functional characterization of a eukaryotic-type protein kinase, SpkB, in the cyanobacterium, Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Kamei, Ayako; Yoshihara, Shizue; Yuasa, Takashi; Geng, Xiaoxing; Ikeuchi, Masahiko

    2003-04-01

    On the basis of the genome sequence, the unicellular motile cyanobacterium Synechocystis sp. PCC 6803 harbors seven putative genes for eukaryotic-type protein kinase belonging to Pkn2 subfamily ( spkA approximately spkG). Previously, SpkA was shown to have protein kinase activity and to be required for cell motility. Here, the role of the spkB was examined. The spkB gene was expressed in Escherichia coli as a fusion protein with His-tag, and the protein was purified by Ni(2+) affinity chromatography. The eukaryotic-type protein kinase activity of the expressed SpkB was demonstrated as autophosphorylation to itself and phosphorylation of the general substrate proteins. SpkB showed autophosphorylation activity in the presence of both Mg(2+) and Mn(2+), but not in Ca(2+). Phenotype analysis of spkB disruptant of Synechocystis revealed that spkB is required for cell motility, but not for phototaxis. These results suggest that SpkB is the eukaryotic-type protein kinase, which regulates cellular motility via protein phosphorylation like SpkA.

  8. Transduction of the light signal during complementary chromatic adaptation in the cyanobacterium Calothrix sp. PCC 7601: DNA-binding proteins and modulation by phosphorylation.

    Science.gov (United States)

    Sobczyk, A; Schyns, G; Tandeau de Marsac, N; Houmard, J

    1993-03-01

    The cyanobacterium Calothrix sp. PCC 7601 can adapt its pigment content in response to changes in the incident light wavelength. It synthesizes, as major light-harvesting pigments, either phycocyanin 2 (PC2, encoded by the cpc2 operon) under red light or phycoerythrin (PE, encoded by the cpeBA operon) under green light conditions. The last step of the signal transduction pathway is characterized by a transcriptional control of the expression of these operons. Partially purified protein extracts were used in gel retardation assays and DNase I footprinting experiments to identify the factors that interact with the promoter region of the cpeBA operon. We found that two proteins, RcaA and RcaB, only detected in extracts of cells grown under green light, behave as positive transcriptional factors for the expression of the cpeBA operon. Treatment of the fractions containing RcaA and RcaB with alkaline phosphatase prevents the binding of RcaA but not of RcaB to the cpeBA promoter region. A post-translational modification of RcaA thus modulates its affinity for DNA.

  9. Heme oxygenase 2 of the cyanobacterium Synechocystis sp. PCC 6803 is induced under a microaerobic atmosphere and is required for microaerobic growth at high light intensity.

    Science.gov (United States)

    Yilmaz, Mete; Kang, Ilgu; Beale, Samuel I

    2010-01-01

    Cyanobacteria, red algae, and cryptomonad algae utilize phycobilin chromophores that are attached to phycobiliproteins to harvest solar energy. Heme oxygenase (HO) in these organisms catalyzes the first step in phycobilin formation through the conversion of heme to biliverdin IXalpha, CO, and iron. The Synechocystis sp. PCC 6803 genome contains two open reading frames, ho1 (sll1184) and ho2 (sll1875), whose products have in vitro HO activity. We report that HO2, the protein encoded by ho2, was induced in the cells growing under a microaerobic atmosphere [0.2% (v/v) O(2)], whereas HO1 was constitutively expressed under both aerobic and microaerobic atmospheres. Light intensity did not have an effect on the expression of both the HOs. Cells, in which ho2 was disrupted, were unable to grow microaerobically at a light intensity of 40 micromol m(-2) s(-1), but did grow microaerobically at 10 micromol m(-2) s(-1) light intensity. These cells grew normally aerobically at both light intensities. Comparative analysis of complete cyanobacterial genomes revealed that possession of two HOs is common in cyanobacteria. In phylogenetic analysis of their amino acid sequences, cyanobacterial HO1 and HO2 homologs formed distinct clades. HO sequences of cyanobacteria that have only one isoform were most similar to HO1 sequences. We propose that HO2 might be the more ancient HO homolog that functioned under low O(2) tension, whereas the derived HO1 can better accommodate increased O(2) tension in the environment.

  10. Anchoring a plant cytochrome P450 via PsaM to the thylakoids in Synechococcus sp. PCC 7002: evidence for light-driven biosynthesis.

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    Lærke Münter Lassen

    Full Text Available Plants produce an immense variety of specialized metabolites, many of which are of high value as their bioactive properties make them useful as for instance pharmaceuticals. The compounds are often produced at low levels in the plant, and due to their complex structures, chemical synthesis may not be feasible. Here, we take advantage of the reducing equivalents generated in photosynthesis in developing an approach for producing plant bioactive natural compounds in a photosynthetic microorganism by functionally coupling a biosynthetic enzyme to photosystem I. This enables driving of the enzymatic reactions with electrons extracted from the photosynthetic electron transport chain. As a proof of concept, we have genetically fused the soluble catalytic domain of the cytochrome P450 CYP79A1, originating from the endoplasmic reticulum membranes of Sorghum bicolor, to a photosystem I subunit in the cyanobacterium Synechococcus sp. PCC 7002, thereby targeting it to the thylakoids. The engineered enzyme showed light-driven activity both in vivo and in vitro, demonstrating the possibility to achieve light-driven biosynthesis of high-value plant specialized metabolites in cyanobacteria.

  11. Lipid profiling of cyanobacteria Synechococcus sp. PCC 7002 using two-dimensional liquid chromatography with quadrupole time-of-flight mass spectrometry.

    Science.gov (United States)

    Shan, Yabing; Liu, Yiqun; Yang, Li; Nie, Honggang; Shen, Sensen; Dong, Chunxia; Bai, Yu; Sun, Qing; Zhao, Jindong; Liu, Huwei

    2016-10-01

    Glycerolipid is a main component of membranes in oxygenic photosynthetic organisms. Up to now, the majority of publication in this area has focused on the physiological functions of glycerolipids and lipoprotein complexes in photosynthesis, but the study on the separation and identification of glycerolipids in thylakoid membrane in cyanobacteria is relatively rare. Here we report a new method to separate and identify five photosynthetic glycerolipid classes, including monoglucosyl diacylglycerol, monogalactosyl diacylglycerol, digalactosyl diacylglycerol, sulfoquinovosyl diacylglycerol, and phosphatidylglycerol, in cyanobacteria Synechococcus sp. PCC 7002 by two-dimensional (normal- and reversed-phase) liquid chromatography online coupled to quadrupole time-of-flight mass spectrometry. Over twice as many lipid species were detected by our method compared to the previously reported methods. Ten new odd-chain fatty acid glycerolipids were discovered for the first time. Moreover, complete separation of isomers of monogalactosyl diacylglycerol and monoglucosyl diacylglycerol was achieved. According to the tandem mass spectrometry results, we found that the head group of monoglucosyl diacylglycerols was not as stable as that of monogalactosyl diacylglycerols, which might explain why the organism chose monogalactosyl diacylglycerols and digalactosyl diacylglycerols instead of monoglucosyl diacylglycerols as the main content of the photosynthetic membranes in the history of evolution. This work will benefit further research on the physiological function of glycerolipids.

  12. An unusual gene arrangement for the putative chromosome replication origin and circadian expression of dnaN in Synechococcus sp. strain PCC 7942.

    Science.gov (United States)

    Liu, Y; Tsinoremas, N F

    1996-06-12

    In eubacteria, the clustering of DnaA boxes around the dnaN (beta subunit of DNA polymerase III) and dnaA genes usually defines the chromosome replication origin (oriC). In this study, the dnaN locus from the cyanobacterium Synechococcus sp. strain PCC 7942 was sequenced. The gene order in this region is cbbZp-dnaN-orf288-purL-purF which contrasts with other eubacteria. A cluster of eleven DnaA boxes (consensus sequence: TTTTCCACA) was found in the intergenic region between dnaN and cbbZp. We also found a 41-bp sequence within this region that is 80% identical to the proposed oriC of Streptomyces coelicolor. Therefore, we propose that this intergenic region may serve as an oriC in Synechococcus. Using bacterial luciferase as a reporter, we also showed that dnaN is rhythmically expressed, suggesting that DNA replication could be under circadian control in this organism.

  13. Disruption of the ndhF1 gene affects Chl fluorescence through state transition in the Cyanobacterium Synechocystis sp. PCC 6803, resulting in apparent high efficiency of photosynthesis.

    Science.gov (United States)

    Ogawa, Takako; Harada, Tetsuyuki; Ozaki, Hiroshi; Sonoike, Kintake

    2013-07-01

    In Synechocystis sp. PCC 6803, the disruption of the ndhF1 gene (slr0844), which encodes a subunit of one of the NDH-1 complexes (NDH-1L complex) serving for respiratory electron transfer, causes the largest change in Chl fluorescence induction kinetics among the kinetics of 750 disruptants searched in the Fluorome, the cyanobacterial Chl fluorescence database. The cause of the explicit phenotype of the ndhF1 disruptant was examined by measurements of the photosynthetic rate, Chl fluorescence and state transition. The results demonstrate that the defects in respiratory electron transfer obviously have great impact on Chl fluorescence in cyanobacteria. The inactivation of NDH-1L complexes involving electron transfer from NDH-1 to plastoquinone (PQ) would result in the oxidation of the PQ pool, leading to the transition to State 1, where the yield of Chl fluorescence is high. Apparently, respiration, although its rate is far lower than that of photosynthesis, could affect Chl fluorescence through the state transition as leverage. The disruption of the ndhF1 gene caused lower oxygen-evolving activity but the estimated electron transport rate from Chl fluorescence measurements was faster in the mutant than in the wild-type cells. The discrepancy could be ascribed to the decreased level of non-photochemical quenching due to state transition. One must be cautious when using the Chl fluorescence parameter to estimate photosynthesis in mutants defective in state transition.

  14. Sortase-mediated ligation of PsaE-modified photosystem I from Synechocystis sp. PCC 6803 to a conductive surface for enhanced photocurrent production on a gold electrode.

    Science.gov (United States)

    Le, Rosemary K; Raeeszadeh-Sarmazdeh, Maryam; Boder, Eric T; Frymier, Paul D

    2015-01-27

    Sortase-mediated ligation was used to attach the photosystem I (PSI) complex from Synechocystis sp. PCC 6803 in a preferential orientation to enhance photoinduced electron flow to a conductive gold surface. Ideally, this method can result in a uniform monolayer of protein, covalently bound unidirectionally to the electrode surface. The exposed C-termini of the psaE subunits of the PSI trimer were targeted to contain an LPETG-sortase recognition sequence to increase noncompeting electron transfer by uniformly orienting the PSI stromal side proximal to the surface. Surface characterization with atomic force microscopy suggested that monolayer formation and optimal surface coverage occurred when the gold surfaces were incubated with peptide at 100 to 500 μM concentrations. When photochronoamperometry with potassium ferrocyanide and ferricyanide as redox mediators was used, photocurrents in the range of 100 to 200 nA/cm(2) were produced, which is an improvement over other attachment techniques for photosystem monolayers that produce approximately 100 nA/cm(2) or less. This work demonstrated that sortase-mediated ligation aided in the control of PSI orientation on modified gold surfaces with a distribution of 94% stromal side proximal and 6% lumenal side proximal to the surface for current-producing PSI.

  15. Resistance, accumulation and transformation of selenium by the cyanobacterium Synechocystis sp. PCC 6803 after exposure to inorganic Se{sup VI} or Se{sup IV}

    Energy Technology Data Exchange (ETDEWEB)

    Gouget, B.; Avoscan, L.; Collins, R.; Carriere, M. [Lab. Pierre Suee, CEA-CNRS UMR 9956, CEA/Saclay, Gif-sur-Yvette (France); Sarret, G. [Environmental Geochemistry Group, LGIT, Univ. of Grenoble and CNRS, Grenoble (France)

    2005-07-01

    Our purpose was to investigate the ability of Synechocystis sp. PCC 6803, a photosynthetic prokaryote isolated from fresh water, to resist, incorporate and reduce the oxidized forms of selenium including selenite and selenate, the major selenium species present in aquatic systems. Selenium speciation and the chemical intermediates during selenium transformation were determined by X-ray absorption near edge structure (XANES) spectroscopy. The possible internalisation pathways involving selenium and the metabolic fate of selenate and selenite were examined. Selenate metabolism seemed to proceed via the sulfate reduction pathway resulting in the formation of the R-Se-H, R-Se-R and R-Se-Se-R species. The transformation of selenate to toxic amino acids may explain the high sensitivity of Synechocystis to selenate. Several mechanisms of selenium reduction seem to complete during selenite assimilation. A specific mechanism may transform internalised selenite into selenide and, subsequently induce the biosynthesis of selenoproteins. A non-specific mechanism may interfere with thiols, such as glutathione in the cell cytoplasm, or with proteins in the periplasm of the bacteria, notably thioredoxins. Several hypotheses concerning the complex transformation of selenium in Synechocystis could therefore be proposed. (orig.)

  16. Overexpression of AhpC enhances stress tolerance and N2-fixation in Anabaena by upregulating stress responsive genes.

    Science.gov (United States)

    Shrivastava, Alok Kumar; Pandey, Sarita; Dietz, Karl Josef; Singh, Prashant Kumar; Singh, Shilpi; Rai, Ruchi; Rai, Lal Chand

    2016-11-01

    The study explores the significance of peroxides in regulating the CO2- and N2-fixation capacities in Anabaena sp. PCC7120. To this end Anabaena strains were generated carrying an extra copy of ahpC (An+ahpC) or by deleting from their endogenous functional ahpC (AnΔahpC). AhpC levels were 2.2- to 6.0-fold higher in An+ahpC than in wild type. An+ahpC revealed 1.4- to 2-fold upregulation of photosystems I and II, nitrogenase, superoxide dismutase and catalase activities while same activities were 1.3- to 2.5-fold downregulated in the insertional mutant (AnΔahpC) compared to the wild type. Peroxide, superoxide and malondialdehyde contents were low in An+ahpC and high in AnΔahpC. Growth was inhibited in AnΔahpC by approximately 40-60% compared to a 33-40% enhanced growth in An+ahpC under selected stresses. Most interestingly, heterocyst frequency was increased in An+ahpC. In order to address transcriptional and posttranscriptional effects, transcripts of genes including groEL, fld, kat, gor, gst, dps, bfr, tf, sodA, dnaK, prx, uspA, pcs and apx were quantified and found to be increased 1.33- to 7.70-fold in unstressed and 1.76- to 13.80-fold in stressed An+ahpC. In a converse manner, they were downregulated by 1.20- to 7.50-fold in unstressed and 1.23 to 10.20-fold in stressed AnΔahpC. It is concluded that the level of AhpC controls a major set of metabolic and developmental genes in normal and stress conditions and thus likely is in the core of the redox regulatory system of Anabaena.

  17. Far-red light photoacclimation (FaRLiP) in Synechococcus sp. PCC 7335. II.Characterization of phycobiliproteins produced during acclimation to far-red light.

    Science.gov (United States)

    Ho, Ming-Yang; Gan, Fei; Shen, Gaozhong; Bryant, Donald A

    2017-02-01

    Phycobilisomes (PBS) are antenna complexes that harvest light for photosystem (PS) I and PS II in cyanobacteria and some algae. A process known as far-red light photoacclimation (FaRLiP) occurs when some cyanobacteria are grown in far-red light (FRL). They synthesize chlorophylls d and f and remodel PS I, PS II, and PBS using subunits paralogous to those produced in white light. The FaRLiP strain, Leptolyngbya sp. JSC-1, replaces hemidiscoidal PBS with pentacylindrical cores, which are produced when cells are grown in red or white light, with PBS with bicylindrical cores when cells are grown in FRL. This study shows that the PBS of another FaRLiP strain, Synechococcus sp. PCC 7335, are not remodeled in cells grown in FRL. Instead, cells grown in FRL produce bicylindrical cores that uniquely contain the paralogous allophycocyanin subunits encoded in the FaRLiP cluster, and these bicylindrical cores coexist with red-light-type PBS with tricylindrical cores. The bicylindrical cores have absorption maxima at 650 and 711 nm and a low-temperature fluorescence emission maximum at 730 nm. They contain ApcE2:ApcF:ApcD3:ApcD2:ApcD5:ApcB2 in the approximate ratio 2:2:4:6:12:22, and a structural model is proposed. Time course experiments showed that bicylindrical cores were detectable about 48 h after cells were transferred from RL to FRL and that synthesis of red-light-type PBS continued throughout a 21-day growth period. When considered in comparison with results for other FaRLiP cyanobacteria, the results here show that acclimation responses to FRL can differ considerably among FaRLiP cyanobacteria.

  18. Unusual radioresistance of nitrogen-fixing cultures of Anabaena strains

    Indian Academy of Sciences (India)

    Harinder Singh; Tonina Fernandes; Shree Kumar Apte

    2010-09-01

    Nitrogen-fixing cultures of two species of the filamentous, heterocystous cyanobacterium Anabaena, namely Anabaena sp. strain L-31 and Anabaena torulosa were found to be highly tolerant to 60Co gamma radiation. No adverse effect on diazotrophic growth and metabolism were observed up to a dose of 5 kGy. At higher doses, radiation tolerance showed a correspondence with the inherent osmotolerance, with Anabaena L-31 being the more radiation tolerant as well as osmotolerant strain. In Anabaena L-31, exposure to 6 kGy of gamma rays resulted in genome disintegration, but did not reduce viability. Irradiation delayed heterocyst differentiation and nitrogen fixation, and marginally affected diazotrophic growth. All the affected parameters recovered after a short lag, without any discernible post-irradiation phenotype. The radiation tolerance of these Gram-negative photoautodiazotrophs is comparable with that of the adiazotrophic photoautotrophic cyanobacterium Chroococcidiopsis or adiazotrophic heterotroph Deinococcus radiodurans. This is the first report of extreme radioresistance in nitrogen-fixing Anabaena cultures.

  19. 鱼腥藻PCC7120藻红蓝蛋白操纵子A、E和F基因的克隆、表达和活性分析%CLONING EXPRESSION AND ACTIVITY ANALYSIS OF A,E,F GENES OF ANABAENA PCC 7120 PEC-OPERON

    Institute of Scientific and Technical Information of China (English)

    孙亚楠; 武栋; 周明; 赵开弘

    2004-01-01

    通过PCR技术从鱼腥藻PCC7120总DNA中扩增藻红蓝蛋白A基因(pecA)、E基因(pecE)、F基因(pecF),将pecA、pecE、pecF分别克隆于pBluescript,然后将pecA、pecE、pecF基因分别插入表达载体pET30a进行高效表达.pecA表达产物藻红蓝蛋白α亚基脱辅基蛋白PecA与藻蓝胆素PCB在pecE/pecF表达产物裂合异构酶PecE/PecF催化下进行体外重组,产物经提纯后,用紫外可见吸收光谱和荧光光谱检测,结果表明生成的色素藻胆蛋白具有藻红蓝蛋白α-亚基所特有的光谱性质和可逆光致变色性质.

  20. Inactivation of Ca(2+)/H(+) exchanger in Synechocystis sp. strain PCC 6803 promotes cyanobacterial calcification by upregulating CO(2)-concentrating mechanisms.

    Science.gov (United States)

    Jiang, Hai-Bo; Cheng, Hui-Min; Gao, Kun-Shan; Qiu, Bao-Sheng

    2013-07-01

    Cyanobacteria are important players in the global carbon cycle, accounting for approximately 25% of global CO2 fixation. Their CO2-concentrating mechanisms (CCMs) are thought to play a key role in cyanobacterial calcification, but the mechanisms are not completely understood. In Synechocystis sp. strain PCC 6803, a single Ca(2+)/H(+) exchanger (Slr1336) controls the Ca(2+)/H(+) exchange reaction. We knocked out the exchanger and investigated the effects on cyanobacterial calcification and CCMs. Inactivation of slr1336 significantly increased the calcification rate and decreased the zeta potential, indicating a relatively stronger Ca(2+)-binding ability. Some genes encoding CCM-related components showed increased expression levels, including the cmpA gene, which encodes the Ca(2+)-dependent HCO3(-) transporter BCT1. The transcript level of cmpA in the mutant was 30 times that in wild type. A Western blot analysis further confirmed that protein levels of CmpA were higher in the mutant than the wild type. Measurements of inorganic carbon fluxes and O2 evolution proved that both the net HCO3(-) uptake rate and the BCT1 transporter supported photosynthetic rate in the slr1336 mutant were significantly higher than in the wild type. This would cause the mutant cells to liberate more OH(-) ions out of the cell and stimulate CaCO3 precipitation in the microenvironment. We conclude that the mutation of the Ca(2+)/H(+) exchanger in Synechocystis promoted the cyanobacterial calcification process by upregulating CCMs, especially the BCT1 HCO3(-) transporter. These results shed new light on the mechanism by which CCM-facilitated photosynthesis promotes cyanobacterial calcification.

  1. Functional analysis of the iron-stress induced CP 43' polypeptide of PS II in the cyanobacterium Synechococcus sp. PCC 7942.

    Science.gov (United States)

    Falk, S; Samson, G; Bruce, D; Huner, N P; Laudenbach, D E

    1995-07-01

    Under conditions of iron-stress, the Photosystem II associated chlorophyll a protein complex designated CP 43', which is encoded by the isiA gene, becomes the major pigment-protein complex in Synechococcus sp. PCC 7942. The isiB gene, which is located immediately downstream of isiA, encodes the protein flavodoxin, which can functionally replace ferredoxin under conditions of iron stress. We have constructed two cyanobacterial insertion mutants which are lacking (i) the CP 43' apoprotein (designated isiA (-)) and (ii) flavodoxin (designated isiB (-)). The function of CP 43' was studied by comparing the cell characteristics, PS II functional absorption cross-sections and Chl a fluorescence parameters from the wild-type, isiA (-) and isiB (-) strains grown under iron-stressed conditions. In all strains grown under iron deprivation, the cell number doubling time was maintained despite marked changes in pigment composition and other cell characteristics. This indicates that iron-starved cells remained viable and that their altered phenotype suggests an adequate acclimation to low iron even in absence of CP 43' and/or flavodoxin. Under both iron conditions, no differences were detected between the three strains in the functional absorption crossection of PS II determined from single turnover flash saturation curves of Chl a fluorescence. This demonstrates that CP 43' is not part of the functional light-harvesting antenna for PS II. In the wild-type and the isiB (-) strain grown under iron-deficient conditions, CP 43' was present in the thylakoid membrane as an uncoupled Chl-protein complex. This was indicated by (1) an increase of the yield of prompt Chl a fluorescence (Fo) and (2) the persistence after PS II trap closure of a fast fluorescence decay component showing a maximum at 685 nm.

  2. Transcription profiling of the model cyanobacterium Synechococcus sp. strain PCC 7002 by NextGen (SOLiD™ Sequencing of cDNA

    Directory of Open Access Journals (Sweden)

    Marcus eLudwig

    2011-03-01

    Full Text Available The genome of the unicellular, euryhaline cyanobacterium Synechococcus sp. PCC 7002 encodes about 3200 proteins. Transcripts were detected for nearly all annotated open reading frames by a global transcriptomic analysis by Next-Generation (SOLiDTM sequencing of cDNA. In the cDNA samples sequenced, ~90% of the mapped sequences were derived from the 16S and 23S ribosomal RNAs and ~10% of the sequences were derived from mRNAs. In cells grown photoautotrophically under standard conditions (38 °C, 1% (v/v CO2 in air, 250 µmol photons m-2 s-1, the highest transcript levels (up to 2% of the total mRNA for the most abundantly transcribed genes (e. g., cpcAB, psbA, psaA were generally derived from genes encoding structural components of the photosynthetic apparatus. High light exposure for one hour caused changes in transcript levels for genes encoding proteins of the photosynthetic apparatus, Type-1 NADH dehydrogenase complex and ATP synthase, whereas dark incubation for one hour resulted in a global decrease in transcript levels for photosynthesis-related genes and an increase in transcript levels for genes involved in carbohydrate degradation. Transcript levels for pyruvate kinase and the pyruvate dehydrogenase complex decreased sharply in cells incubated in the dark. Under dark anoxic (fermentative conditions, transcript changes indicated a global decrease in transcripts for respiratory proteins and suggested that cells employ an alternative phosphoenolpyruvate degradation pathway via phosphoenolpyruvate synthase (ppsA and the pyruvate:ferredoxin oxidoreductase (nifJ. Finally, the data suggested that an apparent operon involved in tetrapyrrole biosynthesis and fatty acid desaturation, acsF2-ho2-hemN2-desF, may be regulated by oxygen concentration.

  3. The optimal mutagen dosage to induce point-mutations in Synechocystis sp. PCC6803 and its application to promote temperature tolerance.

    Directory of Open Access Journals (Sweden)

    Ulrich M Tillich

    Full Text Available Random mutagenesis is a useful tool to genetically modify organisms for various purposes, such as adaptation to cultivation conditions, the induction of tolerances, or increased yield of valuable substances. This is especially attractive for systems where it is not obvious which genes require modifications. Random mutagenesis has been extensively used to modify crop plants, but even with the renewed interest in microalgae and cyanobacteria for biofuel applications, there is relatively limited current research available on the application of random mutagenesis for these organisms, especially for cyanobacteria. In the presented work we characterized the lethality and rate of non-lethal point mutations for ultraviolet radiation and methyl methanesulphonate on the model cyanobacteria Synechocystis sp. PCC6803. Based on these results an optimal dosage of 10-50 J/m(2 for UV and either 0.1 or 1 v% for MMS was determined. A Synechocystis wildtype culture was then mutagenized and selected for increased temperature tolerance in vivo. During the second round of mutagenesis the viability of the culture was monitored on a cell by cell level from the treatment of the cells up to the growth at an increased temperature. After four distinct rounds of treatment (two with each mutagen the temperature tolerance of the strain was effectively raised by about 2°C. Coupled with an appropriate in vivo screening, the described methods should be applicable to induce a variety of desirable characteristics in various strains. Coupling random mutagenesis with high-throughput screening methods would additionally allow to select for important characteristics for biofuel production, which do not yield a higher fitness and can not be selected for in vivo, such as fatty acid concentration. In a combined approach with full genome sequencing random mutagenesis could be used to determine suitable target-genes for more focused methods.

  4. ApcD is necessary for efficient energy transfer from phycobilisomes to photosystem I and helps to prevent photoinhibition in the cyanobacterium Synechococcus sp. PCC 7002.

    Science.gov (United States)

    Dong, Chunxia; Tang, Aihui; Zhao, Jindong; Mullineaux, Conrad W; Shen, Gaozhong; Bryant, Donald A

    2009-09-01

    Phycobilisomes (PBS) are the major light-harvesting, protein-pigment complexes in cyanobacteria and red algae. PBS absorb and transfer light energy to photosystem (PS) II as well as PS I, and the distribution of light energy from PBS to the two photosystems is regulated by light conditions through a mechanism known as state transitions. In this study the quantum efficiency of excitation energy transfer from PBS to PS I in the cyanobacterium Synechococcus sp. PCC 7002 was determined, and the results showed that energy transfer from PBS to PS I is extremely efficient. The results further demonstrated that energy transfer from PBS to PS I occurred directly and that efficient energy transfer was dependent upon the allophycocyanin-B alpha subunit, ApcD. In the absence of ApcD, cells were unable to perform state transitions and were trapped in state 1. Action spectra showed that light energy transfer from PBS to PS I was severely impaired in the absence of ApcD. An apcD mutant grew more slowly than the wild type in light preferentially absorbed by phycobiliproteins and was more sensitive to high light intensity. On the other hand, a mutant lacking ApcF, which is required for efficient energy transfer from PBS to PS II, showed greater resistance to high light treatment. Therefore, state transitions in cyanobacteria have two roles: (1) they regulate light energy distribution between the two photosystems; and (2) they help to protect cells from the effects of light energy excess at high light intensities.

  5. The optimal mutagen dosage to induce point-mutations in Synechocystis sp. PCC6803 and its application to promote temperature tolerance.

    Science.gov (United States)

    Tillich, Ulrich M; Lehmann, Sandra; Schulze, Katja; Dühring, Ulf; Frohme, Marcus

    2012-01-01

    Random mutagenesis is a useful tool to genetically modify organisms for various purposes, such as adaptation to cultivation conditions, the induction of tolerances, or increased yield of valuable substances. This is especially attractive for systems where it is not obvious which genes require modifications. Random mutagenesis has been extensively used to modify crop plants, but even with the renewed interest in microalgae and cyanobacteria for biofuel applications, there is relatively limited current research available on the application of random mutagenesis for these organisms, especially for cyanobacteria. In the presented work we characterized the lethality and rate of non-lethal point mutations for ultraviolet radiation and methyl methanesulphonate on the model cyanobacteria Synechocystis sp. PCC6803. Based on these results an optimal dosage of 10-50 J/m(2) for UV and either 0.1 or 1 v% for MMS was determined. A Synechocystis wildtype culture was then mutagenized and selected for increased temperature tolerance in vivo. During the second round of mutagenesis the viability of the culture was monitored on a cell by cell level from the treatment of the cells up to the growth at an increased temperature. After four distinct rounds of treatment (two with each mutagen) the temperature tolerance of the strain was effectively raised by about 2°C. Coupled with an appropriate in vivo screening, the described methods should be applicable to induce a variety of desirable characteristics in various strains. Coupling random mutagenesis with high-throughput screening methods would additionally allow to select for important characteristics for biofuel production, which do not yield a higher fitness and can not be selected for in vivo, such as fatty acid concentration. In a combined approach with full genome sequencing random mutagenesis could be used to determine suitable target-genes for more focused methods.

  6. Acetylome analysis reveals the involvement of lysine acetylation in photosynthesis and carbon metabolism in the model cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Mo, Ran; Yang, Mingkun; Chen, Zhuo; Cheng, Zhongyi; Yi, Xingling; Li, Chongyang; He, Chenliu; Xiong, Qian; Chen, Hui; Wang, Qiang; Ge, Feng

    2015-02-06

    Cyanobacteria are the oldest known life form inhabiting Earth and the only prokaryotes capable of performing oxygenic photosynthesis. Synechocystis sp. PCC 6803 (Synechocystis) is a model cyanobacterium used extensively in research on photosynthesis and environmental adaptation. Posttranslational protein modification by lysine acetylation plays a critical regulatory role in both eukaryotes and prokaryotes; however, its extent and function in cyanobacteria remain unexplored. Herein, we performed a global acetylome analysis on Synechocystis through peptide prefractionation, antibody enrichment, and high accuracy LC-MS/MS analysis; identified 776 acetylation sites on 513 acetylated proteins; and functionally categorized them into an interaction map showing their involvement in various biological processes. Consistent with previous reports, a large fraction of the acetylation sites are present on proteins involved in cellular metabolism. Interestingly, for the first time, many proteins involved in photosynthesis, including the subunits of phycocyanin (CpcA, CpcB, CpcC, and CpcG) and allophycocyanin (ApcA, ApcB, ApcD, ApcE, and ApcF), were found to be lysine acetylated, suggesting that lysine acetylation may play regulatory roles in the photosynthesis process. Six identified acetylated proteins associated with photosynthesis and carbon metabolism were further validated by immunoprecipitation and Western blotting. Our data provide the first global survey of lysine acetylation in cyanobacteria and reveal previously unappreciated roles of lysine acetylation in the regulation of photosynthesis. The provided data set may serve as an important resource for the functional analysis of lysine acetylation in cyanobacteria and facilitate the elucidation of the entire metabolic networks and photosynthesis process in this model cyanobacterium.

  7. Functional differentiation of two analogous coproporphyrinogen III oxidases for heme and chlorophyll biosynthesis pathways in the cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Goto, Takeaki; Aoki, Rina; Minamizaki, Kei; Fujita, Yuichi

    2010-04-01

    Coproporphyrinogen III oxidase (CPO) catalyzes the oxidative decarboxylation of coproporphyrinogen III to form protoporphyrinogen IX in heme biosynthesis and is shared in chlorophyll biosynthesis in photosynthetic organisms. There are two analogous CPOs, oxygen-dependent (HemF) and oxygen-independent (HemN) CPOs, in various organisms. Little information on cyanobacterial CPOs has been available to date. In the genome of the cyanobacterium Synechocystis sp. PCC 6803 there is one hemF-like gene, sll1185, and two hemN-like genes, sll1876 and sll1917. The three genes were overexpressed in Escherichia coli and purified to homogeneity. Sll1185 showed CPO activity under both aerobic and anaerobic conditions. While Sll1876 and Sll1917 showed absorbance spectra indicative of Fe-S proteins, only Sll1876 showed CPO activity under anaerobic conditions. Three mutants lacking one of these genes were isolated. The Deltasll1185 mutant failed to grow under aerobic conditions, with accumulation of coproporphyrin III. This growth defect was restored by cultivation under micro-oxic conditions. The growth of the Deltasll1876 mutant was significantly slower than that of the wild type under micro-oxic conditions, while it grew normally under aerobic conditions. Coproporphyrin III was accumulated at a low but significant level in the Deltasll1876 mutant grown under micro-oxic conditions. There was no detectable phenotype in Deltasll1917 under the conditions we examined. These results suggested that sll1185 encodes HemF as the sole CPO under aerobic conditions and that sll1876 encodes HemN operating under micro-oxic conditions, together with HemF. Such a differential operation of CPOs would ensure the stable supply of tetrapyrrole pigments under environments where oxygen levels fluctuate greatly.

  8. Photosynthetic Regulation of the Cyanobacterium Synechocystis sp. PCC 6803 Thioredoxin System and Functional Analysis of TrxB (Trx x) and TrxQ (Trx y) Thioredoxins

    Institute of Scientific and Technical Information of China (English)

    M. Esther Pérez-Pérez; Eugenio Martín-Figueroa; Francisco J. Florencio

    2009-01-01

    The expression of the genes encoding the ferredoxin-thioredoxin system including the ferredoxin-thiore-doxin reductase (FTR) genes ftrC and ftrV and the four different thioredoxin genes trxA (m-type; slr0623), trxB (x-type; slr1139), trxC (sll1057) and trxQ (y-type; slr0233) of the cyanobacterium Synechocystis sp. PCC 6803 has been studied according to changes in the photosynthetic conditions. Experiments of light-dark transition indicate that the expression of all these genes except trxQ decreases in the dark in the absence of glucose in the growth medium. The use of two electron transport inhibitors, 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) and 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB), reveals a differential effect on thioredoxin genes expression being trxC and trxQ almost unaf-fected, whereas trxA, trxB, and the ftr genes are down-regulated. In the presence of glucose, DCMU does not affect gene expression but DBMIB still does. Analysis of the single TrxB or TrxQ and the double TrxB TrxQ Synechocystis mutant strains reveal different functions for each of these thioredoxins under different growth conditions. Finally, a Synechocystis strain was generated containing a mutated version of TrxB (TrxBC34S), which was used to identify the potential in-vivo targets of this thioredoxin by a proteomic analysis.

  9. Trade-Off between Growth and Carbohydrate Accumulation in Nutrient-Limited Arthrospira sp. PCC 8005 Studied by Integrating Transcriptomic and Proteomic Approaches.

    Science.gov (United States)

    Depraetere, Orily; Deschoenmaeker, Frédéric; Badri, Hanène; Monsieurs, Pieter; Foubert, Imogen; Leys, Natalie; Wattiez, Ruddy; Muylaert, Koenraad

    2015-01-01

    Cyanobacteria have a strong potential for biofuel production due to their ability to accumulate large amounts of carbohydrates. Nitrogen (N) stress can be used to increase the content of carbohydrates in the biomass, but it is expected to reduce biomass productivity. To study this trade-off between carbohydrate accumulation and biomass productivity, we characterized the biomass productivity, biomass composition as well as the transcriptome and proteome of the cyanobacterium Arthrospira sp. PCC 8005 cultured under N-limiting and N-replete conditions. N limitation resulted in a large increase in the carbohydrate content of the biomass (from 14 to 74%) and a decrease in the protein content (from 37 to 10%). Analyses of fatty acids indicated that no lipids were accumulated under N-limited conditions. Nevertheless, it did not affect the biomass productivity of the culture up to five days after N was depleted from the culture medium. Transcriptomic and proteomic analysis indicated that de novo protein synthesis was down-regulated in the N-limited culture. Proteins were degraded and partly converted into carbohydrates through gluconeogenesis. Cellular N derived from protein degradation was recycled through the TCA and GS-GOGAT cycles. In addition, photosynthetic energy production and carbon fixation were both down-regulated, while glycogen synthesis was up-regulated. Our results suggested that N limitation resulted in a redirection of photosynthetic energy from protein synthesis to glycogen synthesis. The fact that glycogen synthesis has a lower energy demand than protein synthesis might explain why Arthrospira is able to achieve a similar biomass productivity under N-limited as under N-replete conditions despite the fact that photosynthetic energy production was impaired by N limitation.

  10. Trade-Off between Growth and Carbohydrate Accumulation in Nutrient-Limited Arthrospira sp. PCC 8005 Studied by Integrating Transcriptomic and Proteomic Approaches.

    Directory of Open Access Journals (Sweden)

    Orily Depraetere

    Full Text Available Cyanobacteria have a strong potential for biofuel production due to their ability to accumulate large amounts of carbohydrates. Nitrogen (N stress can be used to increase the content of carbohydrates in the biomass, but it is expected to reduce biomass productivity. To study this trade-off between carbohydrate accumulation and biomass productivity, we characterized the biomass productivity, biomass composition as well as the transcriptome and proteome of the cyanobacterium Arthrospira sp. PCC 8005 cultured under N-limiting and N-replete conditions. N limitation resulted in a large increase in the carbohydrate content of the biomass (from 14 to 74% and a decrease in the protein content (from 37 to 10%. Analyses of fatty acids indicated that no lipids were accumulated under N-limited conditions. Nevertheless, it did not affect the biomass productivity of the culture up to five days after N was depleted from the culture medium. Transcriptomic and proteomic analysis indicated that de novo protein synthesis was down-regulated in the N-limited culture. Proteins were degraded and partly converted into carbohydrates through gluconeogenesis. Cellular N derived from protein degradation was recycled through the TCA and GS-GOGAT cycles. In addition, photosynthetic energy production and carbon fixation were both down-regulated, while glycogen synthesis was up-regulated. Our results suggested that N limitation resulted in a redirection of photosynthetic energy from protein synthesis to glycogen synthesis. The fact that glycogen synthesis has a lower energy demand than protein synthesis might explain why Arthrospira is able to achieve a similar biomass productivity under N-limited as under N-replete conditions despite the fact that photosynthetic energy production was impaired by N limitation.

  11. Characterization of the relA/spoT homologue slr1325 (syn-rsh) of the cyanobacterium Synechocystis sp.PCC6803%集胞藻PCC6803中relA/spoT同源基因syn-rsh(slr1325)的鉴定

    Institute of Scientific and Technical Information of China (English)

    缪小刚; 刘惠玲; 宁德刚

    2011-01-01

    [目的]四磷酸或五磷酸鸟苷(Guanosine 3′,5′-bispyrophosphate,(p)ppGpp)是细菌在遭遇环境胁迫时细胞产生应激反应的信号分子,(p)ppGpp由其合成酶RelA或具有合成酶或水解酶双重催化功能的RelA/SpoT合成.本文证明了集胞藻PCC6803(Synechocystis sp.)中唯一编码RelA/SpoT同源蛋白(命名为Syn-RSH)的基因slr1325(syn-rsh)的功能.[方法]通过互补试验证明syn-rsh表达产物的生物学功能;以纤维素薄层层析检测不同条件下Escherichia coli(p)ppGpp合成缺陷突变株及集胞藻PCC6803细胞中的(p)ppGpp.[结果]诱导Syn-RSH表达可使(p)ppGpp合成酶和水解酶基因缺失的E.coli突变株回复野生型表型,并在细胞中积累一定水平的ppGpp;在实验室培养条件下,集胞藻PCC6803细胞中可检测到低水平的ppGpp,氨基酸饥饿可诱导ppGpp水平升高并维持在相应水平.[结论]Syn-RSH具有(p)ppGpp合成酶和水解酶的双重功能,(p)ppGpp是集胞藻PCC6803在实验室生长条件下细胞生长所必需的.

  12. Flavodiiron proteins in oxygenic photosynthetic organisms: photoprotection of photosystem II by Flv2 and Flv4 in Synechocystis sp. PCC 6803.

    Directory of Open Access Journals (Sweden)

    Pengpeng Zhang

    Full Text Available BACKGROUND: Flavodiiron proteins (FDPs comprise a group of modular enzymes that function in oxygen and nitric oxide detoxification in Bacteria and Archaea. The FDPs in cyanobacteria have an extra domain as compared to major prokaryotic enzymes. The physiological role of cyanobacteria FDPs is mostly unknown. Of the four putative flavodiiron proteins (Flv1-4 in the cyanobacterium Synechocystis sp. PCC 6803, a physiological function in Mehler reaction has been suggested for Flv1 and Flv3. PRINCIPAL FINDINGS: We demonstrate a novel and crucial function for Flv2 and Flv4 in photoprotection of photosystem II (PSII in Synechocystis. It is shown that the expression of Flv2 and Flv4 is high under air level of CO(2 and negligible at elevated CO(2. Moreover, the rate of accumulation of flv2 and flv4 transcripts upon shift of cells from high to low CO(2 is strongly dependent on light intensity. Characterization of FDP inactivation mutants of Synechocystis revealed a specific decline in PSII centers and impaired translation of the D1 protein in Delta flv2 and Delta flv4 when grown at air level CO(2 whereas at high CO(2 the Flvs were dispensable. Delta flv2 and Delta flv4 were also more susceptible to high light induced inhibition of PSII than WT or Delta flv1 and Delta flv3. SIGNIFICANCE: Analysis of published sequences revealed the presence of cyanobacteria-like FDPs also in some oxygenic photosynthetic eukaryotes like green algae, mosses and lycophytes. Our data provide evidence that Flv2 and Flv4 have an important role in photoprotection of water-splitting PSII against oxidative stress when the cells are acclimated to air level CO(2. It is conceivable that the function of FDPs has changed during evolution from protection against oxygen in anaerobic microbes to protection against reactive oxygen species thus making the sustainable function of oxygen evolving PSII possible. Higher plants lack FDPs and distinctly different mechanisms have evolved for

  13. The proteolytic activation of the relNEs (ssr1114/slr0664) toxin-antitoxin system by both proteases Lons and ClpP2s/Xs of Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Ning, Degang; Ye, Sen; Liu, Biao; Chang, Jianing

    2011-11-01

    The proteolytic regulation of toxin-antitoxin (TA) systems has been well studied in Escherichia coli but remains unclear in other bacteria. A chromosomal gene pair ssr1114/slr0664, named relNEs, of Synechocystis sp. PCC 6803 forms a TA system belonging to rel family. Here, we used E. coli strain BL21 (DE3) as a host to characterize the proteolytic regulation of relNEs. The proteases of this strain could not degrade the antitoxin RelN, and the ectopic production of the ATP-dependant protease Lons or ClpP2s/Xs of Synechocystis sp. PCC6803 did not affect E. coli growth. Either Lons or ClpP2s/Xs was able to degrade RelN resulting in growth arrest of E. coli due to the activation of RelEs's toxicity, and the presence of RelEs could protect RelN to a certain extent against Lons and ClpP2s/Xs. Our observations suggest that both Lons and ClpP2s/Xs are responsible for RelN proteolysis in the native host under certain conditions. RelN is the first protein substrate identified for cyanobacterial ATP-dependent proteases.

  14. High-Speed Scanning for the Quantitative Evaluation of Glycogen Concentration in Bioethanol Feedstock Synechocystis sp. PCC6803 Using a Near-Infrared Hyperspectral Imaging System with a New Near-Infrared Spectral Camera.

    Science.gov (United States)

    Ishigaki, Mika; Nakanishi, Akihito; Hasunuma, Tomohisa; Kondo, Akihiko; Morishima, Tetsu; Okuno, Toshiaki; Ozaki, Yukihiro

    2017-03-01

    In the present study, the high-speed quantitative evaluation of glycogen concentration accumulated in bioethanol feedstock Synechocystis sp. PCC6803 was performed using a near-infrared (NIR) imaging system with a hyperspectral NIR spectral camera named Compovision. The NIR imaging system has a feature for high-speed and wide area monitoring and the two-dimensional scanning speed is almost 100 times faster than the general NIR imaging systems for the same pixel size. For the quantitative analysis of glycogen concentration, partial least squares regression (PLSR) and moving window PLSR (MWPLSR) were performed with the information of glycogen concentration measured by high performance liquid chromatography (HPLC) and the calibration curves for the concentration within the Synechocystis sp. PCC6803 cell were constructed. The results had high accuracy for the quantitative estimation of glycogen concentration as the best squared correlation coefficient R(2) was bigger than 0.99 and a root mean square error (RMSE) was less than 2.9%. The present results proved not only the potential for the applicability of NIR spectroscopy to the high-speed quantitative evaluation of glycogen concentration in the bioethanol feedstock but also the expansivity of the NIR imaging instrument to in-line or on-line product evaluation on a factory production line of bioethanol in the future.

  15. Growth phase effect on the dark anaerobic hydrogen production in the glucose tolerant mutant of unicellular cyanobacterium Synechocystis sp. strain PCC6803

    Directory of Open Access Journals (Sweden)

    Adipa Chongsuksantikul*

    2015-04-01

    Full Text Available This study has examined the effect of growth phase on hydrogenproduction from cells of a glucose tolerant mutant of Synechocystissp. strain PCC6803. The extracellular products including hydrogen,lactate and acetate from cyanobacteria cells in dark anaerobicnitrate-free solution, yielded different excretory profiles dependingon which growth phases were prepared from photosynthesis. Theamount of hydrogen generated cells prepared from stationary phasewas highest in HEPES buffer and nitrate-free solution, darkanaerobic condition.

  16. Bioinformatic evaluation of L-arginine catabolic pathways in 24 cyanobacteria and transcriptional analysis of genes encoding enzymes of L-arginine catabolism in the cyanobacterium Synechocystis sp. PCC 6803

    Directory of Open Access Journals (Sweden)

    Pistorius Elfriede K

    2007-11-01

    Full Text Available Abstract Background So far very limited knowledge exists on L-arginine catabolism in cyanobacteria, although six major L-arginine-degrading pathways have been described for prokaryotes. Thus, we have performed a bioinformatic analysis of possible L-arginine-degrading pathways in cyanobacteria. Further, we chose Synechocystis sp. PCC 6803 for a more detailed bioinformatic analysis and for validation of the bioinformatic predictions on L-arginine catabolism with a transcript analysis. Results We have evaluated 24 cyanobacterial genomes of freshwater or marine strains for the presence of putative L-arginine-degrading enzymes. We identified an L-arginine decarboxylase pathway in all 24 strains. In addition, cyanobacteria have one or two further pathways representing either an arginase pathway or L-arginine deiminase pathway or an L-arginine oxidase/dehydrogenase pathway. An L-arginine amidinotransferase pathway as a major L-arginine-degrading pathway is not likely but can not be entirely excluded. A rather unusual finding was that the cyanobacterial L-arginine deiminases are substantially larger than the enzymes in non-photosynthetic bacteria and that they are membrane-bound. A more detailed bioinformatic analysis of Synechocystis sp. PCC 6803 revealed that three different L-arginine-degrading pathways may in principle be functional in this cyanobacterium. These are (i an L-arginine decarboxylase pathway, (ii an L-arginine deiminase pathway, and (iii an L-arginine oxidase/dehydrogenase pathway. A transcript analysis of cells grown either with nitrate or L-arginine as sole N-source and with an illumination of 50 μmol photons m-2 s-1 showed that the transcripts for the first enzyme(s of all three pathways were present, but that the transcript levels for the L-arginine deiminase and the L-arginine oxidase/dehydrogenase were substantially higher than that of the three isoenzymes of L-arginine decarboxylase. Conclusion The evaluation of 24

  17. Transducción de señales de estrés por el regulador de respuesta NblR en la cianobacteria Synechococcus sp. PCC7942

    OpenAIRE

    Ruiz Martinich, Diego; Salinas Berná, Paloma; Moronta Barrios, Félix; Cantos Coll, Raquel; Contreras de Vera, Asunción

    2009-01-01

    Mediante el proceso de clorosis o bleaching Synechococcus sp. PCC 7942 degrada los complejos antena del aparato fotosintético en respuesta a carencia prolongada de nitrógeno y otros factores de estrés. La activación del gen nblA, sometido a una compleja regulación, es esencial en este proceso, aunque la adaptación a estrés requiere la regulación de múltiples funciones, la mayoría desconocidas. El regulador de respuesta NblR activa fuertemente a nblA en condiciones de estrés. Además, la histid...

  18. ΔpH-dependent non-photochemical quenching (qE) of excited chlorophylls in the photosystem II core complex of the freshwater cyanobacterium Synechococcus sp PCC 7942.

    Science.gov (United States)

    Stamatakis, Kostas; Papageorgiou, George C

    2014-08-01

    Light-induced and lumen acidity-dependent quenching (qE) of excited chlorophylls (Chl) in vivo has been amply documented in plants and algae, but not in cyanobacteria, using primarily the saturation pulse method of quenching analysis which is applied to continuously illuminated samples. This method is unsuitable for cyanobacteria because the background illumination elicits in them a very large Chl a fluorescence signal, due to a state 2 to state 1 transition, which masks fluorescence changes due to other causes. We investigated the qE problem in the cyanobacterium Synechococcus sp. PCC 7942 using a kinetic method (Chl a fluorescence induction) with which qE can be examined before the onset of the state 2 to state 1 transition and the attendant rise of Chl a fluorescence. Our results confirm the existence of a qE mechanism that operates on excited Chls a in Photosystem II core complexes of cyanobacteria.

  19. Proteome Analyses of Strains ATCC 51142 and PCC 7822 of the Diazotrophic Cyanobacterium Cyanothece sp under Culture Conditions Resulting in Enhanced H-2 Production

    Energy Technology Data Exchange (ETDEWEB)

    Aryal, Uma K.; Callister, Stephen J.; Mishra, Sujata; Zhang, Xiaohui; Shutthanandan, Janani I.; Angel, Thomas E.; Shukla, Anil K.; Monroe, Matthew E.; Moore, Ronald J.; Koppenaal, David W.; Smith, Richard D.; Sherman, Louis

    2013-02-01

    Cultures of the cyanobacterial genus Cyanothece have been shown to produce high levels of biohydrogen. These strains are diazotrophic and undergo pronounced diurnal cycles when grown under N2-fixing conditions in light-dark cycles. We seek to better understand the way in which proteins respond to these diurnal changes and we performed quantitative proteome analysis of Cyanothece ATCC 51142 and PCC 7822 grown under 8 different nutritional conditions. Nitrogenase expression was limited to N2-fixing conditions, and in the absence of glycerol, nitrogenase gene expression was linked to the dark period. However, glycerol induced expression of nitrogenase during part of the light period, together with cytochrome c oxidase (Cox), glycogen phosphorylase (Glp), and glycolytic and pentose-phosphate pathway (PPP) enzymes. This indicated that nitrogenase expression in the light was facilitated via higher respiration and glycogen breakdown. Key enzymes of the Calvin cycle were inhibited in Cyanothece ATCC 51142 in the presence of glycerol under H2 producing conditions, suggesting a competition between these sources of carbon. However, in Cyanothece PCC 7822, the Calvin cycle still played a role in cofactor recycling during H2 production. Our data comprise the first comprehensive profiling of proteome changes in Cyanothece PCC 7822, and allows an in-depth comparative analysis of major physiological and biochemical processes that influence H2-production in both the strains. Our results revealed many previously uncharacterized proteins that may play a role in nitrogenase activity and in other metabolic pathways and may provide suitable targets for genetic manipulation that would lead to improvement of large scale H2 production.

  20. Adapting photosynthesis to the near-infrared: non-covalent binding of phycocyanobilin provides an extreme spectral red-shift to phycobilisome core-membrane linker from Synechococcus sp. PCC7335.

    Science.gov (United States)

    Miao, Dan; Ding, Wen-Long; Zhao, Bao-Qing; Lu, Lu; Xu, Qian-Zhao; Scheer, Hugo; Zhao, Kai-Hong

    2016-06-01

    Phycobiliproteins that bind bilins are organized as light-harvesting complexes, phycobilisomes, in cyanobacteria and red algae. The harvested light energy is funneled to reaction centers via two energy traps, allophycocyanin B and the core-membrane linker, ApcE1 (conventional ApcE). The covalently bound phycocyanobilin (PCB) of ApcE1 absorbs near 660 nm and fluoresces near 675 nm. In cyanobacteria capable of near infrared photoacclimation, such as Synechococcus sp. PCC7335, there exist even further spectrally red shifted components absorbing >700 nm and fluorescing >710 nm. We expressed the chromophore domain of the extra core-membrane linker from Synechococcus sp. PCC7335, ApcE2, in E. coli together with enzymes generating the chromophore, PCB. The resulting chromoproteins, PCB-ApcE2(1-273) and the more truncated PCB-ApcE2(24-245), absorb at 700 nm and fluoresce at 714 nm. The red shift of ~40 nm compared with canonical ApcE1 results from non-covalent binding of the chromophore by which its full conjugation length including the Δ3,3(1) double bond is preserved. The extreme spectral red-shift could not be ascribed to exciton coupling: dimeric PCB-ApcE2(1-273) and monomeric-ApcE2(24-245) absorbed and fluoresced similarly. Chromophorylation of ApcE2 with phycoerythrobilin- or phytochromobilin resulted in similar red shifts (absorption at 615 and 711 nm, fluorescence at 628 or 726 nm, respectively), compared to the covalently bound chromophores. The self-assembled non-covalent chromophorylation demonstrates a novel access to red and near-infrared emitting fluorophores. Brightly fluorescent biomarking was exemplified in E. coli by single-plasmid transformation.

  1. Viruses Infecting a Freshwater Filamentous Cyanobacterium (Nostoc sp. Encode a Functional CRISPR Array and a Proteobacterial DNA Polymerase B

    Directory of Open Access Journals (Sweden)

    Caroline Chénard

    2016-06-01

    Full Text Available Here we present the first genomic characterization of viruses infecting Nostoc, a genus of ecologically important cyanobacteria that are widespread in freshwater. Cyanophages A-1 and N-1 were isolated in the 1970s and infect Nostoc sp. strain PCC 7210 but remained genomically uncharacterized. Their 68,304- and 64,960-bp genomes are strikingly different from those of other sequenced cyanophages. Many putative genes that code for proteins with known functions are similar to those found in filamentous cyanobacteria, showing a long evolutionary history in their host. Cyanophage N-1 encodes a CRISPR array that is transcribed during infection and is similar to the DR5 family of CRISPRs commonly found in cyanobacteria. The presence of a host-related CRISPR array in a cyanophage suggests that the phage can transfer the CRISPR among related cyanobacteria and thereby provide resistance to infection with competing phages. Both viruses also encode a distinct DNA polymerase B that is closely related to those found in plasmids of Cyanothece sp. strain PCC 7424, Nostoc sp. strain PCC 7120, and Anabaena variabilis ATCC 29413. These polymerases form a distinct evolutionary group that is more closely related to DNA polymerases of proteobacteria than to those of other viruses. This suggests that the polymerase was acquired from a proteobacterium by an ancestral virus and transferred to the cyanobacterial plasmid. Many other open reading frames are similar to a prophage-like element in the genome of Nostoc sp. strain PCC 7524. The Nostoc cyanophages reveal a history of gene transfers between filamentous cyanobacteria and their viruses that have helped to forge the evolutionary trajectory of this previously unrecognized group of phages.

  2. Viruses Infecting a Freshwater Filamentous Cyanobacterium (Nostoc sp.) Encode a Functional CRISPR Array and a Proteobacterial DNA Polymerase B

    Science.gov (United States)

    Chénard, Caroline; Wirth, Jennifer F.

    2016-01-01

    ABSTRACT   Here we present the first genomic characterization of viruses infecting Nostoc, a genus of ecologically important cyanobacteria that are widespread in freshwater. Cyanophages A-1 and N-1 were isolated in the 1970s and infect Nostoc sp. strain PCC 7210 but remained genomically uncharacterized. Their 68,304- and 64,960-bp genomes are strikingly different from those of other sequenced cyanophages. Many putative genes that code for proteins with known functions are similar to those found in filamentous cyanobacteria, showing a long evolutionary history in their host. Cyanophage N-1 encodes a CRISPR array that is transcribed during infection and is similar to the DR5 family of CRISPRs commonly found in cyanobacteria. The presence of a host-related CRISPR array in a cyanophage suggests that the phage can transfer the CRISPR among related cyanobacteria and thereby provide resistance to infection with competing phages. Both viruses also encode a distinct DNA polymerase B that is closely related to those found in plasmids of Cyanothece sp. strain PCC 7424, Nostoc sp. strain PCC 7120, and Anabaena variabilis ATCC 29413. These polymerases form a distinct evolutionary group that is more closely related to DNA polymerases of proteobacteria than to those of other viruses. This suggests that the polymerase was acquired from a proteobacterium by an ancestral virus and transferred to the cyanobacterial plasmid. Many other open reading frames are similar to a prophage-like element in the genome of Nostoc sp. strain PCC 7524. The Nostoc cyanophages reveal a history of gene transfers between filamentous cyanobacteria and their viruses that have helped to forge the evolutionary trajectory of this previously unrecognized group of phages. PMID:27302758

  3. 氮磷限制条件下螺旋鱼腥藻产生土嗅素特征研究%Geosminproduction characteristics byAnabaena sp. in nitrogen-limited and phosphorus-limited conditions

    Institute of Scientific and Technical Information of China (English)

    贾晓燕; 刘聪; 储昭升; 庞燕; 胡小贞

    2014-01-01

    Characteristics of Geosminproduced byAnabaenasp. under phosphorus-limited and nitrogen-limited conditions were investigated in batch cultivation and determined using SPME-GC Mass.Anabaena sp. grew well and the growth rate was not influenced by nitrogen limitation. However, its growth was restrained by phosphorus limitation. Heterocyst was produced and its percentage account for 3.5%~4.4% of total cells under nitrogen-limited condition, whereas heterocyst was not produced under phosphorus-limited condition. The geosmin content in cell declined quickly in the first 20d and then kept almost constant. The geosmin content in the late phase was 3.7×10-5ng/cell under nitrogen-limited condition and was a little higher under phosphorus-limited condition (3.2×10-5ng/cell). Chl a concentration under the nitrogen-limited condition was much higher than that under phosphorus-limited condition. The ratio of geosmin content to Chl a content (geosmin/Chl a) under the phosphorus-limited condition (2.3×10-2) was higher than that under nitrogen-limited condition (1.5×10-2).%采用批量培养的方法研究了螺旋鱼腥藻在氮限制和磷限制条件下生长与土嗅素的产生特征.在磷限制条件下螺旋鱼腥藻的生长速率降低,不易生成异形胞;而在氮限制下鱼腥藻生长良好,并生成异形胞,异形胞形成的比例为3.5%~4.4%.在磷限制和氮限制条件下,单位细胞土嗅素的浓度在培养的前20d内都处于急速下降的趋势,之后开始趋于平缓,分别维持在3.18×10-5,3.68×10-5ng/cell左右.氮限制条件下螺旋鱼腥藻单位细胞土嗅素的生成量略高于磷限制条件下.氮限制条件下,螺旋鱼腥藻单位细胞叶绿素 a 的生成量高于磷限制条件下.螺旋鱼腥藻单位细胞产生的土嗅素与叶绿素a的质量比(geosmin/Chl a)在磷限制条件下要高于氮限制条件下.

  4. Spectroscopic analysis of the dark relaxation process of a photocycle in a sensor of blue light using FAD (BLUF) protein Slr1694 of the cyanobacterium Synechocystis sp. PCC6803.

    Science.gov (United States)

    Hasegawa, Koji; Masuda, Shinji; Ono, Taka-Aki

    2005-01-01

    Slr1694 is a BLUF (sensor of blue light using flavin adenine dinucleotide) protein and a putative photoreceptor in the cyanobacterium Synechocystis sp. PCC6803. Illumination of Slr1694 induced a signaling light state concurrent with a red shift in the UV-visible absorption of flavin, and formation of the bands from flavin and apo-protein in the light-minus-dark Fourier transform infrared (FTIR) difference spectrum. Replacement of Tyr8 with phenylalanine abolished these changes. The light state relaxed to the ground dark state, during which the FTIR bands decayed monophasically. These bands were classifiable into three groups according to their decay rates. The C4=O stretching bands of a flavin isoalloxazine ring had the highest decay rate, which corresponded to that of the absorption red shift. The result indicated that the hydrogen bonding at C4=O is responsible for the UV-visible red shift, consistent with the results of density functional calculation. All FTIR bands and the red shift decayed at the same slower rate in deuterated Slr1694. These results indicated that the dark relaxation from the light state is limited by proton transfer. In contrast, a constrained light state formed under dehydrated conditions decayed much more slowly with no deuteration effects. A photocycle mechanism involving the proton transfer was proposed.

  5. The genomic region of rbcLS in Synechococcus sp. PCC 7942 contains genes involved in the ability to grow under low CO2 concentration and in chlorophyll biosynthesis.

    Science.gov (United States)

    Ronen-Tarazi, M; Lieman-Hurwitz, J; Gabay, C; Orus, M I; Kaplan, A

    1995-08-01

    Several genes involved in the ability of Synechococcus sp. PCC 7942 to grow under different CO2 concentrations were mapped in the genomic region of rbcLS (the operon encoding the large and small subunits of ribulose-1,5-bisphosphate carboxylase/oxygenase). Insertion of a cartridge encoding kanamycin resistance within open reading frame (ORF) 78, designated ccmJ, located 7 kb upstream of rbcLS, resulted in a kanamycin-resistant, high-CO2-requiring mutant, M3, which does not contain normal carboxysomes. ccmJ shows significant homology to csoS1 encoding a carboxysomal shell polypeptide in Thiobacillus neopolitanus. Analysis of the polypeptide pattern of a carboxysome-enriched fraction indicated several differences between the wild type and the mutant. The amount of the ribulose-1,5-bisphosphate carboxylase/oxygenase subunits was considerably smaller in the carboxysomal fraction of the mutant when compared to the wild type. On the basis of the sequence analyses, ORF286 and ORF466, located downstream of ccmJ, were identified as chlL and chlN, respectively, which are involved in chlorophyll biosynthesis in the dark.

  6. Trade-Off between Growth and Carbohydrate Accumulation in Nutrient-Limited Arthrospira sp. PCC 8005 Studied by Integrating Transcriptomic and Proteomic Approaches

    OpenAIRE

    2015-01-01

    Cyanobacteria have a strong potential for biofuel production due to their ability to accumulate large amounts of carbohydrates. Nitrogen (N) stress can be used to increase the content of carbohydrates in the biomass, but it is expected to reduce biomass productivity. To study this trade-off between carbohydrate accumulation and biomass productivity, we characterized the biomass productivity, biomass composition as well as the transcriptome and proteome of the cyanobacterium Arthrospira sp. PC...

  7. Mutations of Cytochrome b559 and PsbJ on and near the QC Site in Photosystem II Influence the Regulation of Short-Term Light Response and Photosynthetic Growth of the Cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Huang, Jine-Yung; Chiu, Yi-Fang; Ortega, José M; Wang, Hsing-Ting; Tseng, Tien-Sheng; Ke, Shyue-Chu; Roncel, Mercedes; Chu, Hsiu-An

    2016-04-19

    The characteristic features of two types of short-term light adaptations of the photosynthetic apparatus of the cyanobacterium Synechocystis sp. PCC 6803, state transition and blue-green light-induced fluorescence quenching, were compared in wild-type and cytochrome b559 and PsbJ mutant cells with mutations on and near the QC site in photosystem II (PSII). All mutant cells grew photoautotrophically and assembled stable PSII. Thermoluminescence emission experiments showed a decrease in the stability of the S3QB(-)/S2QB(-) charge pairs in the A16FJ, S28Aβ, and V32Fβ mutant cells. When dark-adapted wild-type and mutant cells were illuminated by medium-intensity blue light, the increase in the PSII fluorescence yield (indicating a transition to state 1) was more prominent in mutant than wild-type cells. Strong blue-light conditions induced a quenching of fluorescence corresponding to nonphotochemical fluorescence quenching (NPQ). The extension of NPQ decreased significantly in the mutants, and the kinetics appeared to be affected. When similar measures were repeated on an orange carotenoid protein (OCP)-deficient background, little or no quenching was observed, which confirms that the decrease in fluorescence under strong blue light corresponded to the OCP-dependent NPQ. Immunoblot results showed that the attenuated effect of blue light-induced NPQ in mutant cells was not due to a lack of OCP. Photosynthetic growth and biomass production were greater for A16FJ, S28Aβ, and V32Fβ mutant cells than for wild-type cells under normal growth conditions. Our results suggest that mutations of cytochrome b559 and PsbJ on and near the QC site of PSII may modulate the short-term light response in cyanobacteria.

  8. The antisense RNA As1_flv4 in the Cyanobacterium Synechocystis sp. PCC 6803 prevents premature expression of the flv4-2 operon upon shift in inorganic carbon supply.

    Science.gov (United States)

    Eisenhut, Marion; Georg, Jens; Klähn, Stephan; Sakurai, Isamu; Mustila, Henna; Zhang, Pengpeng; Hess, Wolfgang R; Aro, Eva-Mari

    2012-09-28

    The functional relevance of natural cis-antisense transcripts is mostly unknown. Here we have characterized the association of three antisense RNAs and one intergenically encoded noncoding RNA with an operon that plays a crucial role in photoprotection of photosystem II under low carbon conditions in the cyanobacterium Synechocystis sp. PCC 6803. Cyanobacteria show strong gene expression dynamics in response to a shift of cells from high carbon to low levels of inorganic carbon (C(i)), but the regulatory mechanisms are poorly understood. Among the most up-regulated genes in Synechocystis are flv4, sll0218, and flv2, which are organized in the flv4-2 operon. The flavodiiron proteins encoded by this operon open up an alternative electron transfer route, likely starting from the Q(B) site in photosystem II, under photooxidative stress conditions. Our expression analysis of cells shifted from high carbon to low carbon demonstrated an inversely correlated transcript accumulation of the flv4-2 operon mRNA and one antisense RNA to flv4, designated as As1_flv4. Overexpression of As1_flv4 led to a decrease in flv4-2 mRNA. The promoter activity of as1_flv4 was transiently stimulated by C(i) limitation and negatively regulated by the AbrB-like transcription regulator Sll0822, whereas the flv4-2 operon was positively regulated by the transcription factor NdhR. The results indicate that the tightly regulated antisense RNA As1_flv4 establishes a transient threshold for flv4-2 expression in the early phase after a change in C(i) conditions. Thus, it prevents unfavorable synthesis of the proteins from the flv4-2 operon.

  9. A Feed-Forward Loop Consisting of the Response Regulator RpaB and the Small RNA PsrR1 Controls Light Acclimation of Photosystem I Gene Expression in the Cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Kadowaki, Taro; Nagayama, Ryuta; Georg, Jens; Nishiyama, Yoshitaka; Wilde, Annegret; Hess, Wolfgang R; Hihara, Yukako

    2016-04-01

    Since cyanobacteria need to decrease PSI content to avoid absorption of excess light energy, down-regulation of PSI gene expression is one of the key characteristics of the high-light (HL) acclimation response. The transcriptional regulator RpaB and the small RNA PsrR1 (photosynthesis regulatory RNA1) have been suggested to be the two most critical factors for this response in Synechocystis sp. PCC 6803. In this study, we found that the HLR1 DNA-binding motif, the recognition sequence for RpaB, is highly conserved in the core promoter region of the psrR1 gene among cyanobacterial species. Gel mobility shift assay revealed that RpaB binds to the HLR1 sequence of psrR1 in vitro. RNA gel blot analysis together with chromatin affinity purification (ChAP) analysis suggested that PSI genes are activated and the psrR1 gene is repressed by the binding of RpaB under low-light (LL) conditions. A decrease in DNA binding affinity of RpaB occurs within 5 min after the shift from LL to HL conditions, leading to the prompt decrease in PSI promoter activity together with derepression of psrR1 gene expression. Accumulating PsrR1 molecules then prevent translation from pre-existing PSI transcripts. By this dual repression at transcriptional and post-transcriptional levels, rapid and strict down-regulation of PSI expression under HL is secured. Our findings suggest that RpaB and PsrR1 constitute a feed-forward loop for the regulation of PSI gene expression to achieve a rapid acclimation response to the damaging HL conditions.

  10. 阻断集胞藻6803PHB合成途径提高胞内NADPH含量%Increasing reductant NADPH content via metabolic engineering of PHB synthesis pathway in Synechocystis sp.PCC 6803

    Institute of Scientific and Technical Information of China (English)

    解鹃; 周杰; 张海峰; 李寅

    2011-01-01

    蓝藻是探索利用太阳能生产化学品的重要微生物,但产量低限制了蓝藻化学品的工业应用.提高宿主还原力水平是提高微生物合成化学品产量的重要手段.为提高集胞藻细胞内NADPH含量,利用同源重组方法,获得敲除聚羟基丁酸酯PHB合酶编码基因phaC和phaE的集胞藻Synechocystis sp.PCC 6803突变体S.△phaC&E.PCR结果证明突变体S.△phaC&E基因组中phaC和phaE已完全被氯霉素抗性基因取代.生长曲线结果显示S.△phaC&E的生长与野生型无明显差异,说明敲除phaC和phaE对蓝藻生长的影响很小.用气相色谱检测胞内PHB含量,野生藻S.wt中PHB为细胞干重的2.3%,而突变体S.△phaC&E中没有PHB生成,该结果说明敲除phaC和phaE能够有效阻断集胞藻中PHB合成.通过对野生藻与突变体进一步比较分析,发现S.△phaC&E胞内NADPH浓度明显提高,在第3天时差异最为明显,S.△phaC&E胞内NADPH浓度是S.wt的2.85倍.总之,敲除phaC和phaE不仅可以通过阻断副产物PHB的合成,而且还节约了NADPH,使胞内还原力NADPH的水平明显提高.因此为提高蓝藻化学品产量提供了可以改变碳流向和具有充足还原力的工程集胞藻.%Cyanobacteria have become attractive hosts for renewable chemicals production. The low productivity, however, prevents it from industrial application. Reductant NAD(P)H availability is a chief hurdle for the production of reductive metabolites in microbes. To increase NADPH content in Synechocystis sp. PCC 6803, PHB synthase encoding gene phaC and phaE in Synechocystis was inactivated by replacing phaC&E genes with chloromycetin resistance cassette via homologous recombination. PCR analysis showed that mutant S.AphaC&E with complete genome segregation was generated. The comparison between growth curves of S.wt and S.AphaC&E indicated the knockout of phaC & phaE genes did not affect obviously the cell growth. Gas chromatography analysis showed that the

  11. Preparation of Polyclonal Antibody of Allophycocyanin Protein in the Cyanobacterium Synechocystis sp.Strain PCC 6803%集胞藻6803藻胆体别藻蓝蛋白多克隆抗体的制备

    Institute of Scientific and Technical Information of China (English)

    陈李萍; 杜玲瑜; 马为民; 王全喜

    2012-01-01

    Phycobilisome is the major accessory light-harvesting supramolecular complexes, which is composed of core and peripheral rods. Furthermore,the core contains several cylindrical protein assemblies that mainly consist of allophycocyanin,and is involved in the transfer of light energy to the reaction centers of photosystems. In this study,the apcA gene was amplified from the unicellular cyanobacterium Synechocystis sp. strain PCC 6803. The expression plasmid pET-32a(+)-apcA was constructed and transformed into BL21(DE3)pLysS,and the expression of ApcA protein was induced by IPTG. After purification by His-tag,the recombinant protein pET-ApcA was used to immunize Japanese White Rabbit to obtain the polyclonal antibody. The titer of the polyclonal antibody was detected by ELISA and its specificity was analyzed by immunoblotting. The titer of polyclonal antibody was found to be up to 1 ∶ 1 025 000,and thus possessed a high specificity. A polyclonal allophycocyanin antibody of Synechocystis 6803 was successfully obtained in this study,and it will further help in understanding the important roles of core of cyanobacterial phycobilisome during light energy transfer by using biochemical strategy.%藻胆体是蓝藻细胞主要的捕光天线色素超分子复合体,主要由核心体和外围的杆两部分组成,核心体主要由别藻蓝蛋白组装而成,参与光能向光合作用反应中心的传递.该研究通过PCR扩增出集胞藻6803别藻蓝蛋白a亚基(ApcA)编码基因apcA,构建表达质粒pET-32a(+)-apcA,并将其转入大肠杆菌BL21(DE3)pLysS菌株中;通过IPTG诱导表达重组蛋白,并利用组氨酸标签将可溶性目的蛋白进行亲和纯化后,免疫日本大耳白兔,从而获得多克隆抗体.间接ELISA法揭示ApcA抗体效价可高达1∶1025000;蛋白免疫印迹确定该抗体具有高度特异性.表明该研究成功制备了集胞藻6803藻胆体别藻蓝蛋白多克隆抗体,为进一步研究藻胆体的核心体在光能

  12. Enhanced biohydrogen production by the N{sub 2}-fixing cyanobacterium Anabaena siamensis strain TISTR 8012

    Energy Technology Data Exchange (ETDEWEB)

    Khetkorn, Wanthanee [Program of Biotechnology, Faculty of Science, Chulalongkorn University, Bangkok, 10330 (Thailand); Laboratory of Cyanobacterial Biotechnology, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Phayathai Road, Bangkok, 10330 (Thailand); Department of Photochemistry and Molecular Science, Uppsala University, Box 523, SE-75120, Uppsala (Sweden); Lindblad, Peter [Department of Photochemistry and Molecular Science, Uppsala University, Box 523, SE-75120, Uppsala (Sweden); Incharoensakdi, Aran [Laboratory of Cyanobacterial Biotechnology, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Phayathai Road, Bangkok, 10330 (Thailand)

    2010-12-15

    The efficiency of hydrogen production depends on several factors. We focused on external conditions leading to enhanced hydrogen production when using the N{sub 2}-fixing cyanobacterium Anabaena siamensis TISTR 8012, a novel strain isolated from a rice paddy field in Thailand. In this study, we controlled key factors affecting hydrogen production such as cell age, light intensity, time of light incubation and source of carbon. Our results showed an enhanced hydrogen production when cells, at log phase, were adapted under N{sub 2}-fixing condition using 0.5% fructose as carbon source and a continuous illumination of 200 {mu}E m{sup -2} s{sup -1} for 12 h under anaerobic incubation. The maximum hydrogen production rate was 32 {mu}mol H{sub 2} mg chl a{sup -1} h{sup -1}. This rate was higher than that observed in the model organisms Anabaena PCC 7120, Nostoc punctiforme ATCC 29133 and Synechocystis PCC 6803. This higher production was likely caused by a higher nitrogenase activity since we observed an upregulation of nifD. The production did not increase after 12 h which was probably due to an increased activity of the uptake hydrogenase as evidenced by an increased hupL transcript level. Interestingly, a proper adjustment of light conditions such as intensity and duration is important to minimize both the photodamage of the cells and the uptake hydrogenase activity. Our results indicate that A. siamensis TISTR 8012 has a high potential for hydrogen production with the ability to utilize sugars as substrate to produce hydrogen. (author)

  13. COMPARATIVE GROWTH AND BIOCHEMICAL COMPOSITION OF FOUR STRAINS OF Nostoc AND Anabaena (CYANOBACTERIA, NOSTOCALES IN RELATION TO SODIUM NITRATE

    Directory of Open Access Journals (Sweden)

    Néstor Rosales Loaiza

    2016-04-01

    Full Text Available ABSTRACTNitrogen concentration is an essential parameter in cyanobacterial cultures to produce enriched biomass with biotechnological purposes. Growth and biochemical composition of Nostoc LAUN0015, Nostoc UAM206, Anabaena sp.1 and Anabaena sp.2 were compared at 0, 4.25, 8.5 and 17 mM NaNO3. Cultures under laboratory conditions were maintained for 30 days at a volume of 500 mL. Anabaena sp.1 yielded the highest value of dry mass of 0.26 ± 2.49 mg mL-1 at 8.5 mM NaNO3. For chlorophyll, phycocyanin and phycoerythrin, maximum values were achieved at 17 mM NaNO3 with 18.09 ± 1.74, 102.90 ± 6.73 and 53.47 ± 2.40 μg mL-1, respectively. Nostoc LAUN0015 produced its maximum value of protein 644.86 ± 19.77 μg mL-1, and 890 mg mL-1 of carbohydrates in the absence of nitrogen. This comparative study shows that the most efficient strain for the production of protein, carbohydrates and lipids in diazotrophic conditions corresponded to Nostoc LAUN0015. However, Anabaena sp.1 and Anabaena sp.2 required high nitrogen concentrations to achieve higher values of metabolites, comparing with Nostoc strains. Nitrogen dependence for the production of pigments and high protein production in strains of Anabaena and in diazotrophic conditions for Nostoc was demonstrated. Nostoc can be cultured under nitrogen deficiency and Anabaena in sufficiency, for biomass production enriched with proteins and carbohydrates.Comparación del crecimiento y Composición Bioquímica de cuatro cepas de Nostoc y Anabaena (Cyanobacteria, Nostocales en relación con el nitrato de sodioRESUMENLa concentración de nitrógeno constituye un parámetro esencial en cultivos de cianobacterias para la producción de biomasa enriquecida con fines biotecnológicos. Se comparó el crecimiento y composición bioquímica de las cepas Nostoc LAUN0015, Nostoc UAM206, Anabaena sp.1 y Anabaena sp.2 a 0, 4,25; 8,5 y 17 mM NaNO3. Los cultivos en condiciones de laboratorio fueron mantenidos durante 30 d

  14. Increased heterocyst frequency by patN disruption in Anabaena leads to enhanced photobiological hydrogen production at high light intensity and high cell density.

    Science.gov (United States)

    Masukawa, Hajime; Sakurai, Hidehiro; Hausinger, Robert P; Inoue, Kazuhito

    2017-03-01

    The effects of increasing the heterocyst-to-vegetative cell ratio on the nitrogenase-based photobiological hydrogen production by the filamentous heterocyst-forming cyanobacterium Anabaena sp. PCC 7120 were studied. Using the uptake hydrogenase-disrupted mutant (ΔHup) as the parent, a deletion-insertion mutant (PN1) was created in patN, known to be involved in heterocyst pattern formation and leading to multiple singular heterocysts (MSH) in Nostoc punctiforme strain ATCC 29133. The PN1 strain showed heterocyst differentiation but failed to grow in medium free of combined-nitrogen; however, a spontaneous mutant (PN22) was obtained on prolonged incubation of PN1 liquid cultures and was able to grow robustly on N2. The disruption of patN was confirmed in both PN1 and PN22 by PCR and whole genome resequencing. Under combined-nitrogen limitation, the percentage of heterocysts to total cells in the PN22 filaments was 13-15 and 16-18% under air and 1% CO2-enriched air, respectively, in contrast to the parent ΔHup which formed 6.5-11 and 9.7-13% heterocysts in these conditions. The PN22 strain exhibited a MSH phenotype, normal diazotrophic growth, and higher H2 productivity at high cell concentrations, and was less susceptible to photoinhibition by strong light than the parent ΔHup strain, resulting in greater light energy utilization efficiency in H2 production on a per unit area basis under high light conditions. The increase in MSH frequency shown here appears to be a viable strategy for enhancing H2 productivity by outdoor cultures of cyanobacteria in high-light environments.

  15. Relationships between the ABC-exporter HetC and peptides that regulate the spatiotemporal pattern of heterocyst distribution in Anabaena.

    Directory of Open Access Journals (Sweden)

    Laura Corrales-Guerrero

    Full Text Available In the model cyanobacterium Anabaena sp. PCC 7120, cells called heterocysts that are specialized in the fixation of atmospheric nitrogen differentiate from vegetative cells of the filament in the absence of combined nitrogen. Heterocysts follow a specific distribution pattern along the filament, and a number of regulators have been identified that influence the heterocyst pattern. PatS and HetN, expressed in the differentiating cells, inhibit the differentiation of neighboring cells. At least PatS appears to be processed and transferred from cell to cell. HetC is similar to ABC exporters and is required for differentiation. We present an epistasis analysis of these regulatory genes and of genes, hetP and asr2819, successively downstream from hetC, and we have studied the localization of HetC and HetP by use of GFP fusions. Inactivation of patS, but not of hetN, allowed differentiation to proceed in a hetC background, whereas inactivation of hetC in patS or patS hetN backgrounds decreased the frequency of contiguous proheterocysts. A HetC-GFP protein is localized to the heterocysts and especially near their cell poles, and a putative HetC peptidase domain was required for heterocyst differentiation but not for HetC-GFP localization. hetP is also required for heterocyst differentiation. A HetP-GFP protein localized mostly near the heterocyst poles. ORF asr2819, which we denote patC, encodes an 84-residue peptide and is induced upon nitrogen step-down. Inactivation of patC led to a late spreading of the heterocyst pattern. Whereas HetC and HetP appear to have linked functions that allow heterocyst differentiation to progress, PatC may have a role in selecting sites of differentiation, suggesting that these closely positioned genes may be functionally related.

  16. Erective Sea Embankment with PCC Piles

    Institute of Scientific and Technical Information of China (English)

    LIU Han-long; FEI Kang; DENG An; ZHANG Ting

    2005-01-01

    The sea embankment is a critical civil works in marine and coastal engineering. In this study, an innovative technique is proposed for constructing erective sea embankments. In the construction of sea embankments, this technique integrates PCC pile installation, PVDs drainage systems, and geotextile reinforcements, resulting in sea embankments with PCC piles. In the application of a sea embankment with PCC piles, PCC piles are employed as the retaining structures;the soft sea ground inside PCC piles is drained and improved by PVDs and vacuum-surcharge combined preloading; geotextile-reinforced backfills lying over the improved soft ground form the embankment body. Brief descrptions of the fundamentals, design and construction of the sea embankment with PCC piles are presented. A case study on the stability of sea embankment with PCC piles is presented as well.

  17. Cloning and sequencing of the ferredoxin gene of blue-green alga Anabaena siamensis

    Science.gov (United States)

    Li, Shou-Dong; Song, Li-Rong; Liu, Yong-Ding; Zhao, Jin-Dong

    1998-03-01

    The structure gene for ferredoxin, petFI, from Anabaena siamensis has been amplified by polymerase chain reaction(PCR) and cloned into cloning vector pGEM-3zf(+). The nucleotide sequence of petFI has been determined with silver staining sequencing method. There is 96.8% homology between coding region of petFI from A. siamensis and that of petFI from A. sp. 7120. Amino acid sequences of seven strains of blue-green algae are compared.

  18. Crystallization, X-ray diffraction analysis and SIRAS/molecular-replacenent phasing of three crystal forms of Anabaena sensory rhodopsin transducer

    Energy Technology Data Exchange (ETDEWEB)

    Vogeley, Lutz; Luecke, Hartmut, E-mail: hudel@uci.edu [University of California, Irvine (United States)

    2006-04-01

    Crystals of Anabaena sensory rhodopsin transducer, the transducer for the cyanobacterial photosensor Anabaena sensory rhodopsin, obtained in the space groups P4, C2 and P2{sub 1}2{sub 1}2{sub 1} diffract to 1.8, 2.1 and 2.0 Å, respectively. Phases for these crystal forms were obtained by SIRAS phasing using an iodide quick-soak derivative (P4) and molecular replacement (C2 and P2{sub 1}2{sub 1}2{sub 1}). Anabaena sensory rhodopsin transducer (ASRT) is a 14.7 kDa soluble signaling protein associated with the membrane-embedded light receptor Anabaena sensory rhodopsin (ASR) from Anabaena sp., a freshwater cyanobacterium. Crystals of ASRT were obtained in three different space groups, P4, C2 and P2{sub 1}2{sub 1}2{sub 1}, which diffract to 1.8, 2.1 and 2.0 Å, respectively. Phases for one of these crystal forms (P4) were obtained by SIRAS phasing using an iodide quick-soak derivative and a partial model was built. Phases for the remaining crystal forms were obtained by molecular replacement using the partial model from the P4 crystal form.

  19. 致乏库蚊幼虫摄食和消化鱼腥藻的观察%THE OBSERVATION OF FEEDING ABILITY OF CULEX PIPIEN FATIGANS LARVAE ON ANABAENA

    Institute of Scientific and Technical Information of China (English)

    张世萍; 王方雨; 朱艳芳; 但丽; 喻子牛

    2005-01-01

    Under the laboratory condition, the larvae of Culex pipens fatigans may feed mainly on Anabaena sp and complete their life cycle. The retention time of Anabaena sp. in larval intestine is about 6 hours while that of Saccharomyces sp. is about 5hours, meaning that Anabaena sp. is not so digestible for the larvae. From hatching to pupation, the larvae fed with Anabaena sp. lasted 194 hours and those fed with Saccharomyces sp were 142 hours, showing that the duration for completing larval stage of the former is 52 hours, which is longer than those fed on Saccharomyces.%在实验室条件下,致乏库蚊幼虫可大量摄食鱼腥藻,并能消化利用,完成生活史.鱼腥藻在蚊幼虫肠道中滞留时间约6h,酵母约5h,鱼腥藻比酵母稍难消化.蚊幼虫至化蛹时期相比,饲喂鱼腥藻为194h,而饲喂酵母的为142h,饲喂鱼腥藻比饲喂酵母延缓了蚊幼虫期52h.

  20. Penggunaan precipitated calcium carbonate (PCC sebagai filler untuk sol karet sepatu olah raga

    Directory of Open Access Journals (Sweden)

    Herminiwati

    2010-12-01

    Full Text Available Abstract The objective of the research was to investigate the utilization of Precipitated Calcium Carbonate (PCC as filler in producing sport shoe rubber soles. PCC is a white filler needed for production of nonblack colour rubber products. There are four types of PCC that have been used including two local PCC from Wonosari and East Java, and two imported PCC from Japan and Taiwan. The amount of PCC added into the sport shoe sole rubber compound was varied in 30,45,60,75 and 90 per hundred rubber (phr. The compounding was carried-out by using two roll mills machine, and the compound was subsequently measured their optimum vulcanization time by using rheometer. The produced compound was then subjected to vulcanistion process by using hydrolic press at temperature 1500C and pressure 150 kg/ cm2. The quality of shoes sole vulcanisates were compare to standard quality of SNI. 12-7075-2005 about cemented system sport shoes. The results indicated that the best formula of rubber compound for sport shoes sole were made by using NR 80 phr, NBR 20 phr, paraffinic oil 10 phr, aluminium silicate 30 phr, ZnO 5 phr, TiO2 10 phr, stearic acid 1 phr, vulkanox SP 1 phr, paraffin wax 1 phr, TMTD 0,5 phr, CBS 2 phr, sulphur 1,2 phr with the amount of PCC Actifort 700 of 45 phr. The best formula meet the requirement SNI 12-7075-2005 and they were characterized by tensile sterength 16,79 N/mm2, elongation at break 529,92% tear resistance 9,06 N/mm2, specific gravity 1,28 g/cm3, hardness 55 shore A, Grasselli absrassion resistancing filler. The local PCC from Wonosari can be used for substitution of the imported PCC as the white filler for the production of rubber compound sport shoes sole. However, particle size reduction and coating or surface treatment of local PCC were needed for improving the quality and the role of reinforcing filler.

  1. Comparative transcriptomics between Synechococcus PCC 7942 and Synechocystis PCC 6803 provide insights into mechanisms of stress acclimation.

    Directory of Open Access Journals (Sweden)

    Konstantinos Billis

    Full Text Available Synechococcus sp. PCC 7942 and Synechocystis sp. PCC 6803 are model cyanobacteria from which the metabolism and adaptive responses of other cyanobacteria are inferred. Using stranded and 5' enriched libraries, we measured the gene expression response of cells transferred from reference conditions to stress conditions of decreased inorganic carbon, increased salinity, increased pH, and decreased illumination at 1-h and 24-h after transfer. We found that the specific responses of the two strains were by no means identical. Transcriptome profiles allowed us to improve the structural annotation of the genome i.e. identify possible missed genes (including anti-sense, alter gene coordinates and determine transcriptional units (operons. Finally, we predicted associations between proteins of unknown function and biochemical pathways by revealing proteins of known functions that are co-regulated with the unknowns. Future studies of these model organisms will benefit from the cataloging of their responses to environmentally relevant stresses, and improvements in their genome annotations found here.

  2. comparative transcriptomics between Synechococcus PCC 7942 and Synechocystis PCC 6803 provide insights into mechanisms of adaptation to stress.

    Energy Technology Data Exchange (ETDEWEB)

    Konstantinos, Billis [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); European Bioinformatics Inst., Hinxton, Cambridge (United Kingdom). European Molecular Biology Lab.; Aristotle Univ., Thessaloniki (Greece). Dept. of Genetics; Billini, Maria [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); Max Planck Inst. for Terrestrial Microbiology, Marburg (Germany); Tripp, Harry J. [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); Kyrpides, Nikos C. [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); Mavrommatis, Konstantinos [USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); Celgene Corp, San Francisco, CA (United States)

    2014-03-21

    Background: Synechococcus sp. PCC 7942 and Synechocystis sp. PCC 6803 are model cyanobacteria from which the metabolism and adaptive responses of other cyanobacteria are inferred. Here we report the gene expression response of these two strains to a variety of nutrient and environmental stresses of varying duration, using transcriptomics. Our data comprise both stranded and 5? enriched libraries in order to elucidate many aspects of the transcriptome. Results: Both organisms were exposed to stress conditions due to nutrient deficiency (inorganic carbon) or change of environmental conditions (salinity, temperature, pH, light) sampled at 1 and 24 hours after the application of stress. The transcriptome profile of each strain revealed similarities and differences in gene expression for photosynthetic and respiratory electron transport chains and carbon fixation. Transcriptome profiles also helped us improve the structural annotation of the genome and identify possible missed genes (including anti-sense) and determine transcriptional units (operons). Finally, we predicted association of proteins of unknown function biochemical pathways by associating them to well-characterized ones based on their transcript levels correlation. Conclusions: Overall, this study results an informative annotation of those species and the comparative analysis of the response of the two organisms revealed similarities but also significant changes in the way they respond to external stress and the duration of the response

  3. Improved Alkane Production in Nitrogen-Fixing and Halotolerant Cyanobacteria via Abiotic Stresses and Genetic Manipulation of Alkane Synthetic Genes.

    Science.gov (United States)

    Kageyama, Hakuto; Waditee-Sirisattha, Rungaroon; Sirisattha, Sophon; Tanaka, Yoshito; Mahakhant, Aparat; Takabe, Teruhiro

    2015-07-01

    Cyanobacteria possess the unique capacity to produce alkane. In this study, effects of nitrogen deficiency and salt stress on biosynthesis of alkanes were investigated in three kinds of cyanobacteria. Intracellular alkane accumulation was increased in nitrogen-fixing cyanobacterium Anabaena sp. PCC7120, but decreased in non-diazotrophic cyanobacterium Synechococcus elongatus PCC7942 and constant in a halotolerant cyanobacterium Aphanothece halophytica under nitrogen-deficient condition. We also found that salt stress increased alkane accumulation in Anabaena sp. PCC7120 and A. halophytica. The expression levels of two alkane synthetic genes were not upregulated significantly under nitrogen deficiency or salt stress in Anabaena sp. PCC7120. The transformant Anabaena sp. PCC7120 cells with additional alkane synthetic gene set from A. halophytica increased intracellular alkane accumulation level compared to control cells. These results provide a prospect to improve bioproduction of alkanes in nitrogen-fixing halotolerant cyanobacteria via abiotic stresses and genetic engineering.

  4. Evidence that histidine forms a coordination bond to the A(0A) and A(0B) chlorophylls and a second H-bond to the A(1A) and A(1B) phylloquinones in M688H(PsaA) and M668H(PsaB) variants of Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Sun, Junlei; Hao, Sijie; Radle, Matthew; Xu, Wu; Shelaev, Ivan; Nadtochenko, Victor; Shuvalov, Vladimir; Semenov, Alexey; Gordon, Heather; van der Est, Art; Golbeck, John H

    2014-08-01

    The axial ligands of the acceptor chlorophylls, A(0A) and A(0B), in Photosystem I are the Met sulfur atoms of M688(PsaA) and M668(PsaB). To determine the role of the Met, His variants were generated in Synechocystis sp. PCC 6803. Molecular dynamics simulations on M688H(PsaA) show that there exist low energy conformations with the His coordinated to A(0A) and possibly H-bonded to A(1A). Transient EPR studies on M688H(PsaA) indicate a more symmetrical electron spin distribution in the A(1A) phyllosemiquinone ring consistent with the presence of an H-bond to the C1 carbonyl. Ultrafast optical studies on the variants show that the 150fs charge separation between P₇₀₀ and A(0) remains unaffected. Studies on the ns timescale show that 57% of the electrons are transferred from A(0A)(-) to A(1A) in M688H(PsaA) and 48% from A(0B)(-) to A(1B) in M668H(PsaB); the remainder recombine with P₇₀₀(+) with 1/e times of 25ns and 37ns, respectively. Those electrons that reach A(1A) and A(1B) in the branch carrying the mutation are not transferred to FX, but recombine with P₇₀₀(+) with 1/e times of ~15μs and ~5μs, respectively. Hence, the His is coordinated to A0 in all populations, but in a second population, the His may be additionally H-bonded to A(1). Electron transfer from A(0) to A(1) occurs only in the latter, but the higher redox potentials of A(0) and A(1) as a result of the stronger coordination bond to A(0) and the proposed second H-bond to A(1) preclude electron transfer to the Fe/S clusters.

  5. Carotenoid Biosynthesis in Calothrix sp. 336/3: Composition of Carotenoids on Full Medium, During Diazotrophic Growth and After Long-Term H2 Photoproduction.

    Science.gov (United States)

    Kosourov, Sergey; Murukesan, Gayathri; Jokela, Jouni; Allahverdiyeva, Yagut

    2016-11-01

    The carotenoid composition of the filamentous heterocystous N2-fixing cyanobacterium Calothrix sp. 336/3 was investigated under three conditions: in full medium (non-diazotrophic growth); in the absence of combined nitrogen (diazotrophic growth); and after long-term H2 photoproduction (diazotrophic medium and absence of nitrogen in the atmosphere). Anabaena sp. PCC 7120 and its ΔhupL mutant with disrupted uptake hydrogenase were used as reference strains. Analysis of identified carotenoids and enzymes involved in carotenogenesis showed the presence of three distinct biosynthetic pathways in Calothrix sp. 336/3. The first one is directed towards biosynthesis of myxoxanthophylls, such as myxol 2'-methylpentoside and 2-hydroxymyxol 2'-methylpentoside. The second pathway results in production of hydroxylated carotenoids, such as zeaxanthin, caloxanthin and nostoxanthin, and the last pathway is responsible for biosynthesis of echinenone and hydroxylated forms of ketocarotenoids, such as 3'-hydroxyechinenone and adonixanthin. We found that carotenogenesis in filamentous heterocystous cyanobacteria varies depending on the nitrogen status of the cultures, with significant accumulation of echinenone during diazotrophic growth at the expense of β-carotene. Under the severe N deficiency and high CO2 supply, which leads to efficient H2 photoproduction, cyanobacteria degrade echinenone and β-carotene, and accumulate glycosylated and hydroxylated carotenoids, such as myxol (or ketomyxol) 2'-methylpentosides, 3'-hydroxyechinenone and zeaxanthin. We suggest that the stability of the photosynthetic apparatus in Calothrix sp. 336/3 cells under N deficiency and high carbon conditions, which also appeared as the partial recovery of the pigment composition by the end of the long-term (∼1 month) H2 photoproduction process, might be mediated by a high content of hydroxycarotenoids.

  6. Structure of plastocyanin from the cyanobacterium Anabaena variabilis

    DEFF Research Database (Denmark)

    Schmidt, Lars; Christensen, Hans Erik Mølager; Harris, Pernille

    2006-01-01

    Plastocyanin from the cyanobacterium Anabaena variabilis was heterologously produced in E. coli and purified. Plate-like crystals were obtained by crystallisation in 1.15 M trisodium citrate and 7.67 mM sodium borate buffer pH 8.5. The crystals belong to the orthorhombic space group P212121...

  7. Spectroscopic studies of Synechococcus sp PCC 7002 phycobilisome core mutants

    Energy Technology Data Exchange (ETDEWEB)

    Gindt, Y.M.

    1993-04-01

    The role of the L[sub cm] (I), [beta][sup 18] (II), and [alpha][sup AP-B] (III) chromoproteins in the phycobilisome (PBS) core was investigated using genetically engineered strains of Synechococcus missing different polypeptides. Intact cells, isolated PBS, and subcore preparations for each mutant were studied to determine the effect of that mutation on energy transfer within the PBS core and to the reaction centers. Three mutants lacked the II and/or III polypeptides, while the I chromophore was altered in others. A lower energy absorbing chromophore, A[sub max] = 695 nm, was substituted for the I chromophore. The deletion of the II and III subunits had no discernible effect on energy transfer from the PBS to PSII. In cells and isolated PBS, the altered I chromophore acts to quench the PBS complex and to redirect the energy which would be transferred to PSII. In the PBS and subcore preparations, deletion of the III subunit did not alter energy transfer within the core. The deletion of the II subunit from the PBS caused a small decrease in the excited state lifetimes of the final emitters indicating more disorder within the core. The I chromophore was found to absorb at 670nm and to emit at 683nm within the intact PBS. The II chromophore emits at 679nm while the III chromophore emits at 682nm. A strong interaction exists between the I chromophore and the II subunit. Upon deletion of the II subunit from the PBS core, the I chromophore emits at a higher energy. The II subunit could act to stabilize the I chromophore-binding pocket, or exciton coupling could be occurring between the two. The role of the III chromophore is still unclear at this time. The III chromophore does contribute to the RT emission of the isolated PBS, but it transfers energy to I at 77 K. One can conclude that the III subunit is adjacent to the trimer containing the I polypeptide.

  8. Spectroscopic studies of Synechococcus sp PCC 7002 phycobilisome core mutants

    Energy Technology Data Exchange (ETDEWEB)

    Gindt, Y.M.

    1993-04-01

    The role of the L{sub cm} (I), {beta}{sup 18} (II), and {alpha}{sup AP-B} (III) chromoproteins in the phycobilisome (PBS) core was investigated using genetically engineered strains of Synechococcus missing different polypeptides. Intact cells, isolated PBS, and subcore preparations for each mutant were studied to determine the effect of that mutation on energy transfer within the PBS core and to the reaction centers. Three mutants lacked the II and/or III polypeptides, while the I chromophore was altered in others. A lower energy absorbing chromophore, A{sub max} = 695 nm, was substituted for the I chromophore. The deletion of the II and III subunits had no discernible effect on energy transfer from the PBS to PSII. In cells and isolated PBS, the altered I chromophore acts to quench the PBS complex and to redirect the energy which would be transferred to PSII. In the PBS and subcore preparations, deletion of the III subunit did not alter energy transfer within the core. The deletion of the II subunit from the PBS caused a small decrease in the excited state lifetimes of the final emitters indicating more disorder within the core. The I chromophore was found to absorb at 670nm and to emit at 683nm within the intact PBS. The II chromophore emits at 679nm while the III chromophore emits at 682nm. A strong interaction exists between the I chromophore and the II subunit. Upon deletion of the II subunit from the PBS core, the I chromophore emits at a higher energy. The II subunit could act to stabilize the I chromophore-binding pocket, or exciton coupling could be occurring between the two. The role of the III chromophore is still unclear at this time. The III chromophore does contribute to the RT emission of the isolated PBS, but it transfers energy to I at 77 K. One can conclude that the III subunit is adjacent to the trimer containing the I polypeptide.

  9. Complete genome sequence of Anabaena variabilis ATCC 29413

    Energy Technology Data Exchange (ETDEWEB)

    Thiel, Teresa [University of Missouri, St. Louis; Pratte, Brenda S. [University of Missouri, St. Louis; Zhong, Jinshun [University of Missouri, St. Louis; Goodwin, Lynne A. [Los Alamos National Laboratory (LANL); Copeland, A [U.S. Department of Energy, Joint Genome Institute; Lucas, Susan [U.S. Department of Energy, Joint Genome Institute; Han, Cliff [Los Alamos National Laboratory (LANL); Pitluck, Sam [U.S. Department of Energy, Joint Genome Institute; Land, Miriam L [ORNL; Kyrpides, Nikos C [U.S. Department of Energy, Joint Genome Institute; Woyke, Tanja [U.S. Department of Energy, Joint Genome Institute

    2013-01-01

    Anabaena variabilis ATCC 29413 is a filamentous, heterocyst-forming cyanobacterium that has served as a model organism, with an extensive literature extending over 40 years. The strain has three distinct nitrogenases that function under different environmental conditions and is capable of photoautotrophic growth in the light and true heterotrophic growth in the dark using fructose as both carbon and energy source. While this strain was first isolated in 1964 in Mississippi and named Ana-baena flos-aquae MSU A-37, it clusters phylogenetically with cyanobacteria of the genus Nostoc. The strain is a moderate thermophile, growing well at approximately 40 C. Here we provide some additional characteristics of the strain, and an analysis of the complete genome sequence.

  10. UV-inducible DNA repair in the cyanobacteria Anabaena spp.

    OpenAIRE

    Levine, E.; Thiel, T

    1987-01-01

    Strains of the filamentous cyanobacteria Anabaena spp. were capable of very efficient photoreactivation of UV irradiation-induced damage to DNA. Cells were resistant to several hundred joules of UV irradiation per square meter under conditions that allowed photoreactivation, and they also photoreactivated UV-damaged cyanophage efficiently. Reactivation of UV-irradiated cyanophage (Weigle reactivation) also occurred; UV irradiation of host cells greatly enhanced the plaque-forming ability of i...

  11. Competition for phosphorus between the nitrogen-fixing cyanobacteria Anabaena and Aphanizomenon

    NARCIS (Netherlands)

    DeNobel, WT; Snoep, JL; Mur, LR

    1997-01-01

    The influence of Na fixation on the P-limited growth of two strains of Anabaena and Aphanizomenon was investigated using continuous cultures. Under N-2-fixing conditions Anabaena had a higher maximum growth rate, a greater affinity for P, a higher yield on P and a higher N-2 fixation activity than A

  12. 中国鱼腥藻属的八个新记录种%EIGHT NEWLY RECORDED SPECIES OF ANABAENA BORY (NOSTOCACEAE, CYANOPHYTA) FROM CHINA

    Institute of Scientific and Technical Information of China (English)

    杨丽; 虞功亮; 李仁辉

    2009-01-01

    menioides Forti 1912、伯氏鱼腥藻Anabaena bergii Ostenfeld 1908、乌克兰鱼腥藻Anabaena ucrainica(Schkorb.)Watanabe 1996、大湖鱼腥藻Anabaena oumiana Watanabe 1996和真紧密鱼腥藻Anabaena eucompacta Li et Watanabe 1999.

  13. Biodegradation of polychlorinated biphenyls (PCBs) by the novel identified cyanobacterium Anabaena PD-1.

    Science.gov (United States)

    Zhang, Hangjun; Jiang, Xiaojun; Lu, Liping; Xiao, Wenfeng

    2015-01-01

    Polychlorinated biphenyls (PCBs), a class of hazardous pollutants, are difficult to dissipate in the natural environment. In this study, a cyanobacterial strain Anabaena PD-1 showed good resistance against PCB congeners. Compared to a control group, chlorophyll a content decreased 3.7% and 11.7% when Anabaena PD-1 was exposed to 2 and 5 mg/L PCBs for 7 d. This cyanobacterial strain was capable of decomposing PCB congeners which was conclusively proved by determination of chloride ion concentrations in chlorine-free medium. After 7 d, the chloride ion concentrations in PCB-treated groups (1, 2, 5 mg/L) were 3.55, 3.05, and 2.25 mg/L, respectively. The genetic information of strain PD-1 was obtained through 16S rRNA sequencing analysis. The GenBank accession number of 16S rRNA of Anabaena PD-1 was KF201693.1. Phylogenetic tree analysis clearly indicated that Anabaena PD-1 belonged to the genus Anabaena. The degradation half-life of Aroclor 1254 by Anabaena PD-1 was 11.36 d; the total degradation rate for Aroclor 1254 was 84.4% after 25 d. Less chlorinated PCB congeners were more likely to be degraded by Anabaena PD-1 in comparison with highly chlorinated congeners. Meta- and para-chlorines in trichlorodiphenyls and tetrachlorobiphenyls were more susceptible to dechlorination than ortho-chlorines during the PCB-degradation process by Anabaena PD-1. Furthermore, Anabaena PD-1 can decompose dioxin-like PCBs. The percent biodegradation of 12 dioxin-like PCBs by strain PD-1 ranged from 37.4% to 68.4% after 25 days. Results above demonstrate that Anabaena PD-1 is a PCB-degrader with great potential for the in situ bioremediation of PCB-contaminated paddy soils.

  14. Biodegradation of polychlorinated biphenyls (PCBs by the novel identified cyanobacterium Anabaena PD-1.

    Directory of Open Access Journals (Sweden)

    Hangjun Zhang

    Full Text Available Polychlorinated biphenyls (PCBs, a class of hazardous pollutants, are difficult to dissipate in the natural environment. In this study, a cyanobacterial strain Anabaena PD-1 showed good resistance against PCB congeners. Compared to a control group, chlorophyll a content decreased 3.7% and 11.7% when Anabaena PD-1 was exposed to 2 and 5 mg/L PCBs for 7 d. This cyanobacterial strain was capable of decomposing PCB congeners which was conclusively proved by determination of chloride ion concentrations in chlorine-free medium. After 7 d, the chloride ion concentrations in PCB-treated groups (1, 2, 5 mg/L were 3.55, 3.05, and 2.25 mg/L, respectively. The genetic information of strain PD-1 was obtained through 16S rRNA sequencing analysis. The GenBank accession number of 16S rRNA of Anabaena PD-1 was KF201693.1. Phylogenetic tree analysis clearly indicated that Anabaena PD-1 belonged to the genus Anabaena. The degradation half-life of Aroclor 1254 by Anabaena PD-1 was 11.36 d; the total degradation rate for Aroclor 1254 was 84.4% after 25 d. Less chlorinated PCB congeners were more likely to be degraded by Anabaena PD-1 in comparison with highly chlorinated congeners. Meta- and para-chlorines in trichlorodiphenyls and tetrachlorobiphenyls were more susceptible to dechlorination than ortho-chlorines during the PCB-degradation process by Anabaena PD-1. Furthermore, Anabaena PD-1 can decompose dioxin-like PCBs. The percent biodegradation of 12 dioxin-like PCBs by strain PD-1 ranged from 37.4% to 68.4% after 25 days. Results above demonstrate that Anabaena PD-1 is a PCB-degrader with great potential for the in situ bioremediation of PCB-contaminated paddy soils.

  15. The rnb gene of Synechocystis PCC6803 encodes a RNA hydrolase displaying RNase II and not RNase R enzymatic properties.

    Directory of Open Access Journals (Sweden)

    Rute G Matos

    Full Text Available Cyanobacteria are photosynthetic prokaryotic organisms that share characteristics with bacteria and chloroplasts regarding mRNA degradation. Synechocystis sp. PCC6803 is a model organism for cyanobacteria, but not much is known about the mechanism of RNA degradation. Only one member of the RNase II-family is present in the genome of Synechocystis sp PCC6803. This protein was shown to be essential for its viability, which indicates that it may have a crucial role in the metabolism of Synechocystis RNA. The aim of this work was to characterize the activity of the RNase II/R homologue present in Synechocystis sp. PCC6803. The results showed that as expected, it displayed hydrolytic activity and released nucleoside monophosphates. When compared to two E. coli counterparts, the activity assays showed that the Synechocystis protein displays RNase II, and not RNase R characteristics. This is the first reported case where when only one member of the RNase II/R family exists it displays RNase II and not RNase R characteristics.

  16. New Anabaena and Nostoc cyanophages from sewage settling ponds

    Energy Technology Data Exchange (ETDEWEB)

    Hu, N.; Thiel, T.; Giddings, T.H., Jr.; Wolk, C.P.

    1981-10-15

    We have isolated, from sewage settling ponds, 16 cyanophages for heterocyst forming, filamentous cyanobacteria of the genera Anabaena and Nostoc. These phages fall into three groups based on morphology, host range, one-step growth curves, and restriction digests. On the basis of these criteria they can be distinguished from cyanophages A-1(L), A-4(L), N-1, and AN-10 which we received from other laboratories. Certain of the newly described phages are similar in morphology to the short-tailed LPP cyanophages, and others to the long-tailed AS cyanophages.

  17. Influence of Nutrient Sources on Anabaena spiroides Growth and Odorous Compounds Production Characteristics%不同营养源条件下螺旋鱼腥藻生长与产嗅特征研究

    Institute of Scientific and Technical Information of China (English)

    于建伟; 陈克云; 苏命; 杨敏; 刘代成

    2011-01-01

    The occurrence of taste and odors,produced by secondary metabolites of cyanobacteria,has been one of the major water quality problems in drinking water.However,the odorous compounds produced by cyanobacteria usually differ significantly with different species.One cyanobacterium isolated from Yanghe reservoir was identified as Anabaena sp.,which can produce high level of geosmin consistently during laboratory culture.By culture expanding experiments,the algal growth and geosmin production characteristics of the Anabaena sp.were studied on different conditions of nitrogen and phosphorus sources.The results indicated that geosmin mainly remained in the intracellular algal cells regardless of the nutrient sources,and the extracellular content was only in the range of 0.2%-9.6%.Compared with ammonia nitrogen conditions,the growth of Anabaena sp.in nitrate nitrogen conditions was much higher,with a 1.4-fold variation in geosmin production.While ammonia nitrogen concentration was 0.5 mg/L,the algal biomass and geosmin production achieved the highest level of 3.8×104cells·mL-1 and 1.1×104 ng·L-1,respectively.When the nitrate nitrogen concentration was 2.0 mg/L,the algal biomass and geosmin production achieved the highest level of 6.6×104 cells·mL-1 and 1.3×104ng·L-1,respectively.Compared with nitrogen sources,the growth of Anabaena sp.could be promoted significantly until phosphorus level attained 0.12 mg/L,indicating that phosphorus is the main limiting nutrient source for Anabaena sp..For Yanghe reservoir,the nutrient level has already been enough for the growth of Anabaena sp..Therefore,the nutrient source content,especially phosphorus,should be reduced effectively to control the cyanobacterium bloom and taste and odor problems.%蓝藻次生代谢产物所导致的嗅味问题已成为饮用水的主要水质问题之一,然而不同种属蓝藻的产嗅特征往往差别明显.本研究将从洋河水库中分离得到的可高产土

  18. Synthesis of both enantiomers of isorobinal, a novel cyclic monoterpene isolated from the astigmatid mite, Rhizoglyphus sp.

    Science.gov (United States)

    Liang, Ting; Kuwahara, Shigefumi

    2002-11-01

    Both enantiomers of isorobinal, a cyclic monoterpene isolated from the astigmatid mite (Rhizoglyphus sp.), were synthesized from the enantiomers of perillaldehyde in four steps by using PCC-oxidation of a tertiary allylic alcohol intermediate as the key step.

  19. Anabaenolysins, novel cytolytic lipopeptides from benthic Anabaena cyanobacteria.

    Directory of Open Access Journals (Sweden)

    Jouni Jokela

    Full Text Available Two novel cyclic lipopeptides, anabaenolysin A and anabaenolysin B, were isolated from two benthic cyanobacterial strains of the genus Anabaena. This novel class of cyanobacterial lipopeptides has a general structure of a small peptide ring consisting of four amino acids from which two are proteinogenic and two unusual; glycine(1, glycine(2, 2-(3-amino-5-oxytetrahydrofuran-2-yl-2-hydroxyacetic acid(3 and a long unsaturated C(18 β-amino acid(4 with a conjugated triene structure. They are distinguished by the presence of a conjugated dienic structure in the C18 β-amino acid present in anabaenolysin A but not in anabaenolysin B. Conjugated triene structure generates a typical UV spectrum for anabaenolysins for easy recognition. Anabaenolysin A constituted up to 400 ppm of the cyanobacterial dry weight. We found evidence of thirteen variants of anabaenolysins in one cyanobacterial strain. This suggests that the anabaenolysins are an important class of secondary metabolites in benthic Anabaena cyanobacteria. Both anabaenolysin A and B had cytolytic activity on a number of mammalian cell lines.

  20. BIODEGRADATION OF TEXTILE DYES BY Anabaena flos-aqual

    Directory of Open Access Journals (Sweden)

    Brigida Pimentel Villar de Queiroz

    2011-04-01

    Full Text Available The pollution caused by dumping of toxic waste into the environment has resulted in impairment of essential natural resources such as water. With population growth and industries, the generation of waste increases substantially. Specifically, about 3,000 were commercial dyes to be carcinogenic and have no longer been manufactured, but in third world countries such as Brazil, some of these dyes high commercial value, are still in use. This study aimed to evaluate the possibility of biodegradation of dyes technical Drim CL 2 R Yellow and Blue Drim CL R. We tested the ability of degradation of these dyes by the cyanobacteria blue-green algae Anabaena flos-aqual. For this, their effectiveness in the degradation was evaluated in terms of discoloration spectrophotometrically. The blue dye was greater than R Drim CL degradation rate compared to the yellow dye Drim CL 2R. The species Anabaena flos-aqual achieved high degradation efficiency compared to blue dye, revealing a high potential applicability in processes of textile biodegradations in the county of Americana.

  1. Novel surface associated polyphosphate bodies sequester uranium in the filamentous, marine cyanobacterium, Anabaena torulosa.

    Science.gov (United States)

    Acharya, Celin; Apte, Shree Kumar

    2013-12-01

    A filamentous, heterocystous, nitrogen-fixing marine cyanobacterium, Anabaena torulosa, has been shown to harbour surface associated, acid soluble polyphosphate bodies. Uranium immobilization by such polyphosphate bodies, reported in cyanobacteria for the first time, demonstrates a novel uranium sequestration phenomenon.

  2. [Effect of light and temperature on growth kinetics of Anabaena flosaquae under phosphorus limitation].

    Science.gov (United States)

    Yin, Zhi-Kun; Li, Zhe; Wang, Sheng; Guo, Jin-Song; Xiao, Yan; Liu, Jing; Zhang, Ping

    2015-03-01

    Phosphorus, light and temperature are the key environmental factors leading to algae growth. But the effects of interaction between light and temperature on the growth of Anabaena flosaquae under phosphorus limitation were not well documented in literature. Anabaena flosaquae was selected for the study and lab-scale experiment and simulation were carried out. The results showed that the optimal temperature of Anabaena flosaquae was 20 degrees C under phosphorus limitation when the light intensity was constant, and the optimal light intensity (illuminance) of Anabaena flosaquae was 3 000 lx under phosphorus limitation when the temperature was constant. Based on model fitting and parameter calibration, the optimal temperature and light intensity of Anabaena flosaquae were 21.03 degress C ± 1.55 degrees C and 2 675.12 lx ± 262.93 lx, respectively. These data were close to the actual water environmental condition at the end of spring. Results of this study will provide important foundation for prediction of Anabaena blooms.

  3. A novel potassium deficiency-induced stimulon in Anabaena torulosa

    Indian Academy of Sciences (India)

    Anuradha Alahari; Shree Kumar Apte

    2004-06-01

    Potassium deficiency enhanced the synthesis of fifteen proteins in the nitrogen-fixing cyanobacterium Anabaena torulosa and of nine proteins in Escherichia coli. These were termed potassium deficiency-induced proteins or PDPs and constitute hitherto unknown potassium deficiency–induced stimulons. Potassium deficiency also enhanced the synthesis of certain osmotic stress-induced proteins. Addition of K+ repressed the synthesis of a majority of the osmotic stress-induced proteins and of PDPs in these bacteria. These proteins contrast with the dinitrogenase reductase of A. torulosa and the glycine betaine-binding protein of E. coli, both of which were osmo-induced to a higher level in potassium-supplemented conditions. The data demonstrate the occurrence of novel potassium deficiency-induced stimulons and a wider role of K+ in regulation of gene expression and stress responses in bacteria.

  4. UV-inducible DNA repair in the cyanobacteria Anabaena spp

    Energy Technology Data Exchange (ETDEWEB)

    Levine, E.; Thiel, T.

    1987-09-01

    Strains of the filamentous cyanobacteria Anabaena spp. were capable of very efficient photoreactivation of UV irradiation-induced damage to DNA. Cells were resistant to several hundred joules of UV irradiation per square meter under conditions that allowed photoreactivation, and they also photoreactivated UV-damaged cyanophage efficiently. Reactivation of UV-irradiated cyanophage (Weigle reactivation) also occurred; UV irradiation of host cells greatly enhanced the plaque-forming ability of irradiated phage under nonphotoreactivating conditions. Postirradiation incubation of the host cells under conditions that allowed photoreactivation abolished the ability of the cells to perform Weigle reactivation of cyanophage N-1. Mitomycin C also induced Weigle reactivation of cyanophage N-1, but nalidixic acid did not. The inducible repair system (defined as the ability to perform Weigle reactivation of cyanophages) was relatively slow and inefficient compared with photoreactivation.

  5. Ultrafast photochemistry of anabaena sensory rhodopsin: experiment and theory.

    Science.gov (United States)

    Schapiro, Igor; Ruhman, Sanford

    2014-05-01

    Light induced isomerization of the retinal chromophore activates biological function in all retinal protein (RP) driving processes such as ion-pumping, vertebrate vision and phototaxis in organisms as primitive as archea, or as complex as mammals. This process and its consecutive reactions have been the focus of experimental and theoretical research for decades. The aim of this review is to demonstrate how the experimental and theoretical research efforts can now be combined to reach a more comprehensive understanding of the excited state process on the molecular level. Using the Anabaena Sensory Rhodopsin as an example we will show how contemporary time-resolved spectroscopy and recently implemented excited state QM/MM methods consistently describe photochemistry in retinal proteins. This article is part of a Special Issue entitled: Retinal Proteins - You can teach an old dog new tricks.

  6. AcEST: DK946269 [AcEST

    Lifescience Database Archive (English)

    Full Text Available helatase OS=Anabaena sp. (strain PCC ... 36 0.17 sp|Q55GU9|MSH6_DICDI DNA mismatch repair protein Msh6 OS=Di...t: 352 TSSAEVWNGRIAMLGFIALI-IELVTGQGLL 381 >sp|Q55GU9|MSH6_DICDI DNA mismatch repair protein Msh6

  7. Precipitated calcium carbonate (PCC - cellulose composite fillers: Effects of PCC particle structure on the production and properties of uncoated fine paper

    Directory of Open Access Journals (Sweden)

    Paulapuro, H.

    2007-02-01

    Full Text Available This work examines the precipitation of PCC – pulp composite fillers with varying crystal habits and their effects on the papermaking properties of printing and writing paper. Colloidal (c-PCC, rhombohedral (r-PCC, and scalenohedral types (s-PCC of composite PCCs were produced and compared with commercial reference PCCs. Scanning electron micros-copy showed the c-PCC to be a high-surface-area nano-structured PCC. The rhombohedral composite was formed in clusters like a spider-web structure. Under similar experimental conditions, composite PCC was formed as individual ellipsoidal crystals and some of the particles had malformed structure, in contrast to the structured reference s-PCC. The co-precipitation and the structure of PCC significantly influence the forming, consolidation, and properties of paper, as well as its perform-ance in printing.Composite c-PCC showed the highest retention during forming. At higher filler contents, dewatering was reduced significantly with handsheets containing s- and r-PCC composite fillers. Colloidal composite hand-sheets showed the lowest tensile index and internal bond strength, while the rhombohedral composite gave the highest z-directional bond strength. Compared with the traditional reference samples containing commercial PCCs, paper with s- and r-composites had significantly higher density but similar light scattering ability. Addition of fibrillar fines to fine paper increased print rub fastness significantly in both laser and inkjet printed samples.

  8. 转人粒细胞集落刺激因子(hG-CSF)基因的鱼腥藻的构建%Construction of Anabaena Transferred the Gene Encoding the Human Granulocyte Colony-stimulating Factor

    Institute of Scientific and Technical Information of China (English)

    陈翠丽; 施定基

    2005-01-01

    本研究目的是构建转G-CSF基因的工程鱼腥藻Anabaena sp..首先将b型G-CSF克隆于中间载体pRL 439和穿梭表达载体pDC-8上.通过三亲接合转移将穿梭表达载体pDCG-CSF转入鱼腥藻内.通过PCR扩增的方法在转基因鱼腥藻中检测到G-CSF基因的存在.

  9. Photoreactions and Structural Changes of Anabaena Sensory Rhodopsin

    Directory of Open Access Journals (Sweden)

    Akira Kawanabe

    2009-12-01

    Full Text Available Anabaena sensory rhodopsin (ASR is an archaeal-type rhodopsin found in eubacteria. The gene encoding ASR forms a single operon with ASRT (ASR transducer which is a 14 kDa soluble protein, suggesting that ASR functions as a photochromic sensor by activating the soluble transducer. This article reviews the detailed photoreaction processes of ASR, which were studied by low-temperature Fourier-transform infrared (FTIR and UV-visible spectroscopy. The former research reveals that the retinal isomerization is similar to bacteriorhodopsin (BR, but the hydrogen-bonding network around the Schiff base and cytoplasmic region is different. The latter study shows the stable photoproduct of the all-trans form is 100% 13-cis, and that of the 13-cis form is 100% all-trans. These results suggest that the structural changes of ASR in the cytoplasmic domain play important roles in the activation of the transducer protein, and photochromic reaction is optimized for its sensor function.

  10. Dose assessment intercomparisons within the RENEB network using G0-lymphocyte prematurely condensed chromosomes (PCC assay)

    OpenAIRE

    Terzoudi, Georgia I; Pantelias, Gabriel; Darroudi, Firouz; Barszczewska, Katarzyna; Buraczewska, Iwona; Depuydt, Julie; Georgieva, Dimka; Hadjidekova, Valeria; Hatzi, Vasiliki I.; Karachristou, Ioanna; Karakosta, Maria; Meschini, Roberta; M’kacher, Radhia; Montoro, Alegria; Palitti, Fabrizio

    2017-01-01

    Purpose: Dose assessment intercomparisons within the RENEB network were performed for triage biodosimetry analyzing G0-lymphocyte PCC for harmonization, standardization and optimization of the PCC assay. Materials and methods: Comparative analysis among different partners for dose assessment included shipment of PCC-slides and captured images to construct dose-response curves for up to 6 Gy c-rays. Accident simulation exercises were performed to assess the suitability of the PCC assay by d...

  11. STARCH-SODIUM STEARATE COMPLEX MODIFIED PCC FILLER AND ITS APPLICATION IN PAPERMAKING

    Directory of Open Access Journals (Sweden)

    Huiming Fan,

    2012-06-01

    Full Text Available The use of fillers tends to reduce paper strength, which can limit their application. Therefore research on filler modification is of significant importance in order to overcome this limitation. In this paper, precipitated calcium carbonate (PCC was modified by starch, sodium stearate, and the starch cross-linking agent sodium hexametaphosphate. The purpose of this research is to provide useful references to the industrial application of modified precipitated calcium carbonate (PCC. Modified precipitated calcium carbonate (PCC was characterized by particle size analyzer and scanning electron microscope (SEM. The analysis showed that the particle size of the modified PCC was significantly increased versus the control. The morphology of modified PCC also greatly changed. The influence of modified and unmodified PCC filled paper on paper physical performance was studied. The experimental results showed that at the same ash content, modified PCC filled paper compared with unmodified PCC filled paper had higher brightness, lower opacity, and higher physical strength. The impact of modified and unmodified PCC on stock retention and the comparison between modified and unmodified PCC were investigated. The experimental results showed that the stock filled with modified PCC had better retention compared to those filled with unmodified PCC.

  12. BIOTRANSFORMATION OF 2,4,6-TRINITROTOLUENE (TNT) IN ANABAENA SP. CULTURES. (R825513C013)

    Science.gov (United States)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  13. An ecophysiological study of the Azolla filiculoides- Anabaena azollae association

    Science.gov (United States)

    van Kempen, Monique; Smolders, Fons; Speelman, Eveline; Reichart, Gert Jan; Barke, Judith; Brinkhuis, Henk; Lotter, Andy; Roelofs, Jan

    2010-05-01

    The long term effects of salinity stress on the growth, nutrient content and amino acid composition of the Azolla filiculoides - Anabaena azollae association was studied in a laboratory experiment. It was demonstrated that the symbiosis could tolerate salt stress up to 90 mM NaCl, even after a 100 day period of preconditioning at salt concentrations that were 30 mM NaCl lower. In the 120 mM NaCl treatment the Azolla filiculoides survived, but hardly any new biomass was produced. It was shown that during the experiment, A. filiculoides became increasingly efficient in excluding salt ions from the plant tissue and was thus able to increase its salt tolerance. The amino acid analysis revealed that the naturally occurring high glutamine concentration in the plants was strongly reduced at salt concentrations of 120 mM NaCl and higher. This was the result of the reduced nitrogenase activity at these salt concentrations, as was demonstrated in an acetylene reduction assay. We suggest that the high glutamine concentration in the plants might play a role in the osmoregulatory response against salt stress, enabling growth of the A. filiculoides -Anabaena azollae association up to 90 mM NaCl. In a mesocosm experiment it furthermore was demonstrated that Azolla might manipulate its own microenvironment when grown at elevated salt concentration (up to ~50 mmol•L-1) by promoting salinity stratification, especially when it has formed a dense cover at the water surface. Beside salt stress, we also studied the growth of Azolla filiculoides in response to elevated atmospheric carbon dioxide concentration, in combination with different light intensities and different pH of the nutrient solution. The results demonstrated that as compared to the control (ambient pCO2 concentrations), Azolla filiculoides was able to produce twice as much biomass at carbon dioxide concentrations that were five times as high as the ambient pCO2 concentration. However, it was also shown that this

  14. Anabaena bergii Ostenf. [f. minor (Kisselev Kossinsk.] (Cyanoprokaryota: The first record in Serbia, its taxonomic status, and that of the genus Anabaena Bory ex Born. & Flah.

    Directory of Open Access Journals (Sweden)

    Cvijan M.

    2009-01-01

    Full Text Available Within the framework of a detailed survey of the algal community in salt marshes of the Vojvodina Province (Northern Serbia, we rather unexpectedly found the blue-green alga Anabaena bergii Ostenf. [forma minor (Kisselev Kossinsk.] in water samples from Slatina Pond near Opovo. Our finding represents its first record in Serbia. The present paper gives general characteristics of this alga and of the habitat in which it was found. Based on analysis of a large number of works dealing with characteristics and the taxonomic status of the genus Anabaena, the species A. bergii, and its forma minor, it is concluded that there are numerous problems in taxonomy of the given genus, with no consensus among researchers. In light of the available data, the authors retain the name of the species A. bergii, but accept forma minor with some reserve.

  15. Photosynthetic vesicles with bound phycobilisomes from Anabaena variabilis

    Energy Technology Data Exchange (ETDEWEB)

    Katoh, T.; Gantt, E.

    1979-01-01

    Photosynthetically active vesicles with attached phycobilisomes from Anabaena variabilis, were isolated and shown to transfer excitation energy from phycobiliproteins to F696 chlorophyll (Photosystem II). The best results were obtained when cells were disrupted in a sucrose/phosphate/citrate mixture (0.3:0.5:0.3 M, respectively) containing 1.5% serum albumin. The vesicles showed a phycocyanin/chlorophyll ratio essentially identical to that of whole cells, and oxygen evolution rates of 250 ..mu..mol; O/sub 2//h per mg chlorophyll (with 4 mM ferricyanide added as oxidant), whereas whole cells had rates of up to 450. Excitation of the vesicles by 600 nm light produced fluorescence peaks (-196/sup 0/C) at 644, 662, 685, 695, and 730 nm. On aging of the vesicles, or upon dilution, the fluorescence yield of the 695 nm emission peak gradually decreased with an accompanying increase and final predominant peak at 685 nm. This shift was accompanied by a decrease in the quantum efficiency of Photosystem II activity from an initial 0.05 to as low as 0.01 mol O/sub 2//einstein (605 nm), with a lesser change in the V/sub max/ values. The decrease in the quantum efficiency is mainly attributed to excitation uncoupling between phycobilisomes and Photosystem II. It is concluded that the F685 nm emission peak, often exclusively attributed to Photosystem II chlorophyll, arises from more than one component with phycobilisome emission being a major contributor. Vesicles from which phycobilisomes had been removed, as verified by electron microscopy and spectroscopy, had an almost negligible emission at 685 nm.

  16. Photosynthetic vesicles with bound phycobilisomes from Anabaena variabilis

    Energy Technology Data Exchange (ETDEWEB)

    Katoh, T.; Gantt, E.

    1979-01-01

    Photosynthetically active vesicles with attached phycobilisomes from Anabaena variabilis, were isolated and shown to transfer excitation energy from phycobiliproteins to F696 chlorophyll (Photosystem II). The best results were obtained when cells were disrupted in a sucrose/phosphate/citrate mixture (0.3:0.5:0.3 M, respectively) containing 1.5% serum albumin. The vesicles showed a phycocyanin/chlorophyll ratio essentially identical to that of whole cells, and oxygen evolution rates of 250 ..mu..mol O/sub 2//h per mg chlorophyll (with 4 mM ferricyanide added as oxidant), whereas whole cells had rates of up to 450. Excitation of the vesicles by 600 nm light produced fluorescence peaks (-196/sup 0/C) at 644, 662, 685, 695, and 730 nm. On aging of the vesicles, or upon dilution, the fluorescence yield of the 695 nm emission peak gradually decreased with an accompanying increase and final predominant peak at 685 nm. This shift was accompanied by a decrease in the quantum efficiency of Photosystem II activity from an initial 0.05 to as low as 0.01 mol O/sub 2//einstein (605 nm), with a lesser change in the V/sub max/ values. The decrease in the quantum efficiency is mainly attributed to excitation uncoupling between phycobilisomes and Photosystem II. It is concluded that the F685 nm emission peak, often exclusively attributed to Photosystem II chlorophyll, arises from more than one component with phycobilisome emission being a major contributor. Vesicles from which phycobilisomes had been removed, as verified by electron microscopy and spectroscopy, had an almost negligible emission at 685 nm.

  17. PCC+AC复合式路面技术经济分析%Technical and Economical Performance Analysis of PCC+AC Compound Pavement

    Institute of Scientific and Technical Information of China (English)

    方伟振; 肖亮

    2006-01-01

    通过AC路面、PCC路面、PCC+AC复合式路面技术性能的分析可知PCC+AC复合式路面兼有AC路面和PCC路面的的优点,是一种经济耐用的路面材料.PCC+AC复合式路面的研究和推广应用将产生巨大的经济效益和社会效益.

  18. Transfected parvalbumin alters calcium homeostasis in teratocarcinoma PCC7 cells

    DEFF Research Database (Denmark)

    Müller, B K; Kabos, P; Belhage, B;

    1996-01-01

    Indirect evidence supports a protective role of some EF-hand calcium-binding proteins against calcium-induced neurotoxicity. Little is known about how these proteins influence cytosolic calcium levels. After cloning the parvalbumin cDNA into an expression vector, teratocarcinoma cells (PCC7) were...

  19. GC/MS analysis of piperidinocyclohexanecarbonitrile (PCC) smoking products

    Energy Technology Data Exchange (ETDEWEB)

    Lue, L.P.; Scimeca, J.A.; Thomas, B.F.; Martin, B.R.

    1986-03-05

    Piperidinocyclohexanecarbonitrile (PCC), an intermediate in phencyclidine (PCP) synthesis, is a major contaminant of illicit PCP. Due to the frequent abuse of PCP by smoking, this study was conducted to determine the PCC pyrolysis products delivered in smoke. Marihuana placebo cigarettes were impregnated with /sup 3/H-piperidino-/sup 14/C-cyano-PCC (synthesized in the lab and recrystallized twice, m.p. 67/sup 0/C) and burned under conditions which simulated smoking. Mainstream smoke was passed through glass wool filters and H/sub 2/SO/sub 4/ and NaOH traps. Tritium and /sup 14/C were recovered as 83%, and 56%, respectively, of the starting material. Seventy-six percent of the recovered tritium was found in the glass wool trap followed by 13, 7 and 4% in the acid trap, base trap and in the ash/unburned butt, respectively. Seventy-three percent of the recovered /sup 14/C was found in the glass wool filter and 16 and 8% were found in the acid and base traps, respectively. GC/MS analysis revealed the presence of 1-piperidinocyclohexene (30%), PCC (24%), piperidine (7%), and 1-acetyl-piperidine (5%).

  20. Optimized electroporation-induced transformation in Microcystis aeruginosa PCC7806

    Directory of Open Access Journals (Sweden)

    El Semary, A.

    2010-01-01

    Full Text Available Gene disruption in cyanobacteria is difficult and comprises an obstacle for genetic manipulation. Very few reports tackled this problem but the methods used are usually obscure and hardly reproducible. Here we describe an optimized electroporation-induced transformation in Microcystis aeruginosa PCC7806 where conditions for successful electroporation and transformation are investigated.

  1. Solution Structure of Reduced Plastocyanin from the Blue-Green Alga Anabaena Variabilis

    DEFF Research Database (Denmark)

    Led, J.J.; Badsberg, U.; Jørgensen, A.M.;

    1996-01-01

    The three-dimensional solution structure of plastocyanin from Anabaena variabilis (A.v. PCu) has been determined by nuclear magnetic resonance spectroscopy. Sixty structures were calculated by distance geometry from 1141 distance restraints and 46 dihedral angle restraints. The distance geometry ...

  2. Solution structure of reduced plastocyanin from the blue-green alga Anabaena variabilis

    DEFF Research Database (Denmark)

    Badsberg, U; Jørgensen, A.M.; Gesmar, H;

    1996-01-01

    The three-dimensional solution structure of plastocyanin from Anabaena variabilis (A.v.PCu) has been determined by nuclear magnetic resonance spectroscopy. Sixty structures were calculated by distance geometry from 1141 distance restraints and 46 dihedral angle restraints. The distance geometry s...

  3. Effect of butachlor on growth and nitrogen fixation by Anabaena sphaerica.

    Science.gov (United States)

    Suseela, M R

    2001-07-01

    Present study was carried out to examine the effect of Butachlor on growth and nitrogen fixation by Anabaena sphaerica. The increased concentration of the pesticide did not have any adverse effect on the alga. Rather it accelerated the algal contribution in terms of biomass and nitrogen fixation.

  4. Classification and phylogeny of the cyanobiont Anabaena azollae Strasburger: an answered question?

    Science.gov (United States)

    Pereira, Ana L; Vasconcelos, Vitor

    2014-06-01

    The symbiosis Azolla-Anabaena azollae, with a worldwide distribution in pantropical and temperate regions, is one of the most studied, because of its potential application as a biofertilizer, especially in rice fields, but also as an animal food and in phytoremediation. The cyanobiont is a filamentous, heterocystic cyanobacterium that inhabits the foliar cavities of the pteridophyte and the indusium on the megasporocarp (female reproductive structure). The classification and phylogeny of the cyanobiont is very controversial: from its morphology, it has been named Nostoc azollae, Anabaena azollae, Anabaena variabilis status azollae and recently Trichormus azollae, but, from its 16S rRNA gene sequence, it has been assigned to Nostoc and/or Anabaena, and from its phycocyanin gene sequence, it has been assigned as non-Nostoc and non-Anabaena. The literature also points to a possible co-evolution between the cyanobiont and the Azolla host, since dendrograms and phylogenetic trees of fatty acids, short tandemly repeated repetitive (STRR) analysis and restriction fragment length polymorphism (RFLP) analysis of nif genes and the 16S rRNA gene give a two-cluster association that matches the two-section ranking of the host (Azolla). Another controversy surrounds the possible existence of more than one genus or more than one species strain. The use of freshly isolated or cultured cyanobionts is an additional problem, since their morphology and protein profiles are different. This review gives an overview of how morphological, chemical and genetic analyses influence the classification and phylogeny of the cyanobiont and future research.

  5. Protein (Cyanobacteria): 24330 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available sigma factor Anabaena sp. 90 MEKRDCFELLSAYLDGEVTATERRQVEEWLSNDTSIKCLYKRLLNLRKGLHDIPVPATAQSSEVTINQVLTRVNRRYRLNWMLGGAAAAACILGTISGLFPGNSRMVEIATTQPTELTPTATDSPLMVALNNPVIEIPKTAVATGQKPVNNLN ...

  6. Protein (Cyanobacteria): 24305 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available ing protein Anabaena sp. 90 MNKLIFLDTNILGMVTNPKSSNSNCQECKEWLDELPLKSYQIILPEIADYEVRRELLRAGKTKGIKRLDQLKQAITYLPITTATMLLAAQFWAEIRNTGKPTADPKSLDGDVILAAQAKIEELNGDQVIVATTNVKHLSLFVDAREWQMIN ...

  7. Protein (Cyanobacteria): 264116 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available P Anabaena sp. 90 MDAEELLQKYAAGERIFRSVNLRGVDLEGADLSEIDLTGANLAGADLNDANLSKADLDRTNLTRASLINANLSELVNGSNLNLTGADLSGANLSKANLDKANFSNANLDNAN...LSKANLESANFSNANLDNANLSKANLDSVNFRKASLQGTNLEKADLQTTDLMKANLNGANLKRADLTGVNIYGATFKNADLTGAIM

  8. Upstream factors affecting Tualatin River algae—Tracking the 2008 Anabaena algae bloom to Wapato Lake, Oregon

    Science.gov (United States)

    Rounds, Stewart A.; Carpenter, Kurt D.; Fesler, Kristel J.; Dorsey, Jessica L.

    2015-12-17

    Significant Findings A large bloom that included floating mats of the blue-green algae Anabaena flos-aquae occurred in the lower 20 miles of the Tualatin River in northwestern Oregon between July 7 and July 17, 2008.

  9. Identification of an Algae-lysing Bacterium of Anabaena flosaquae and Primary Research on Their Relationship%一株水华鱼腥藻溶藻菌的分离鉴定及菌藻关系初探

    Institute of Scientific and Technical Information of China (English)

    叶姜瑜; 钟以蓉; 俞岚; 李文娟

    2011-01-01

    [Objective] The aim was to explore the relationship between alage-lysing bacterium and Anabaena flosaquae so as to provide reference for the control of bloom. [Method] An algae-lysing bacterium strain named S7 was isolated from eutrophic river. The lytic efficiency and performing mode of S7 strain to Anabaena flosaquae was studied. Influence of different environmental factors and the relationship between S7 strain and Anabaena flosaquae was also studied, and then the bacterium strain was physiologically identified. [ Result] More than 90% of Anabaena flosaquae had been removed by 7 d when the volume ratio of medium to algae solution was 30% , the pH was 9 and the temperature was 35 ℃. These results also showed that a mutual inhibit relationship existed between S7 strain and Anabaena flosaquae. The S7 strain killed the algae by indirectly through certain lytic agents in absence of direct contact with the target but by secreting metabolites. Moreover, these lytic agents also had the thermostability. 16S rDNA sequence analysis showed that S7 strain belonged to Chryseobactenum sp.. [Conclusion] The examine Poly-p proved that S7 strain was polyphosphate accumulating bacteria(PAOs) and produced better lytic efficiency.%[目的]研究溶藻特性及菌藻关系,为进一步研究溶藻细菌对水华的治理作用提供帮助.[方法]从富营养化水体中分离得到一株有高效溶藻效果的菌株(S7),研究了其对水华鱼腥藻(Anabaena flosaquae)的抑制效果、作用方式和不同环境因子对溶藻效果的影响,以及菌藻关系,并对菌株进行了菌体Poly-p染色、革兰氏染色和分子鉴定.[结果]菌株投加量为藻波量的30%时,7d叶绿素a的去除率达到90%以上.pH为9、温度35℃下藻的去除率最高.S7菌株与水华鱼腥藻形成竞争共栖的生态关系,并通过分泌溶藻物质间接抑制水华鱼腥藻生长,且该物质具有一定的热稳定性.根据生理生化及16S rDNA序列分析鉴定,S7

  10. Evaluation of antibacterial activity of zinc oxide nanoparticles synthesized using phycobilins of Anabaena variabilis NTSS17

    Directory of Open Access Journals (Sweden)

    Thangaraj Ramasamy

    2015-12-01

    Full Text Available Objective: To evaluate the antibacterial activity of zinc oxide nanoparticles synthesized using phycobilins of Anabaena variabilis NTSS17. Methods: The cyanobacterial isolate was collected from paddy field and morphologically identified as Anabaena variabilis NTSS17, that produces a pigment i.e. phycobiliproteins. The biosynthesized zinc nanoparticles were characterized by different spectroscopic and analytical techniques such as UV-visible spectrophotometer, Fourier transform infrared spectroscopy and X-ray diffraction which confirmed the formation of zinc nanoparticles. Results: Antibacterial activity of zinc oxide nanoparticles was examined against Escherichia coli, Rhodococcus rhodochrous and Pseudomonas aeruginosa. The maximum zone of inhibition occurred at 5 mg/1000 mL concentration of zinc oxide nanoparticles. Conclusions: Due to potent antimicrobial and intrinsic properties of zinc oxide, it can be actively used for biomedical applications.

  11. DNA binding activity of Anabaena sensory rhodopsin transducer probed by fluorescence correlation spectroscopy.

    Science.gov (United States)

    Kim, Sung Hyun; Kim, So Young; Jung, Kwang-Hwan; Kim, Doseok

    2015-01-01

    Anabaena sensory rhodopsin transducer (ASRT) is believed to be a major player in the photo-signal transduction cascade, which is triggered by Anabaena sensory rhodopsin. Here, we characterized DNA binding activity of ASRT probed by using fluorescence correlation spectroscopy. We observed clear decrease of diffusion coefficient of DNA upon binding of ASRT. The dissociation constant, K(D), of ASRT to 20 bp-long DNA fragments lied in micro-molar range and varied moderately with DNA sequence. Our results suggest that ASRT may interact with several different regions of DNA with different binding affinity for global regulation of several genes that need to be activated depending on the light illumination.

  12. Quantum yields for the light adaptations in Anabaena sensory rhodopsin and bacteriorhodopsin

    Science.gov (United States)

    Wada, Yoichiro; Kawanabe, Akira; Furutani, Yuji; Kandori, Hideki; Ohtani, Hiroyuki

    2008-02-01

    Archael-type rhodopsin has an all- trans or a 13- cis retinal. The light-induced interconversion between these two forms has been found in Anabaena sensory rhodopsin, even though only the photoreaction from the 13- cis form to the all- trans form exists in bacteriorhodopsin. In this study, we obtained the quantum yields for the 13- cis → all- trans and all- trans → 13- cis reactions of Anabaena sensory rhodopsin (0.24 ± 0.03 and 0.38 ± 0.07, respectively) and concluded that these values were independent of the wavelength of the excitation light as well as bacteriorhodopsin. In other words, no excess energy effects can be found in these reactions.

  13. Characteristics of Anabaena variabilis influencing plaque formation by cyanophage N-1

    Energy Technology Data Exchange (ETDEWEB)

    Currier, T.C.; Wolk, C.P.

    1979-07-01

    Phage N-1 grown in Anabaena strain 7120 (N-1 . 7120) forms plaques on A. variabilis about 10/sup -7/ to 10/sup -6/ as efficiently as on Anabaena 7120. By manipulating different characteristics of the interaction between phage and host, it was possible to increase the relative efficiency of plaque formation to 0.38. Growth of A. variabilis at 40/sup 0/C for at least three generations resulted in an increase in the rate of phage adsorption and a 10-fold increase in the efficiency of plaque formation. The efficiency of plaque formation was further increased about 42-fold, with little or no further increase in rate of adsorption, in a variant strain, A. variabilis strain FD, isolated from a culture of A. variabilis which had grown for more than 30 generations at 40/sup 0/C. The low relative efficiency of plaque formation by N-1 . 7120 on A. variabilis could be partially accounted for if A. variabilis contains a deoxyribonucleic acid restriction endonuclease which is absent from Anabaena 7120. Indirect evidence for such an endonuclease included the following: (i) phage N-1 grown in A. variabilis (N-1 . Av) had approximately a 7 x 10/sup 3/-fold higher relative efficiency of plaque formation on A. variabilis than had N-1 . 7120; and (ii) the efficiency of plaque formation by N-1 . 7120 on A. variabilis strain FD was increased by up to 146-fold after heating the latter organism at 51/sup 0/C.

  14. Effect of OX-VIRIN versus phytoplankton; Eficacia de OX.VIRIN frente a fitoplancton

    Energy Technology Data Exchange (ETDEWEB)

    Sevilla Miguel, E.; Peleato Sanchez, M. L.; Gomez-Moreno Calera, C.; Oros Monje, J.; Vergara Larrayad, Y.

    2003-07-01

    The effect of the peroxide biocides OX-VIRIN has been tested on the survival of several representative phytoplankton species. Scenedesmus vacuolatus green algae, Anabaena sp. PCC7120 filamentous cyanobacteria and Microcystis aeruginosa PCC7005 unicellular cyanobacteria have been used. The parameters used to control the effectiveness of the biocide have been the chlorophyll determination and re culture. It has been shown that OX-VIRIN at dosages of 0.2, 0.5 and 1% is lethal against Microcystis, Anabaena, and Scenedesmus vacuolatus (formerly called Chlorella fusca), being the first mentioned organisms the most sensible to the biocide. (Author)

  15. Junto e misturado, uma etnografia do PCC (Maria Biondi

    Directory of Open Access Journals (Sweden)

    Iván Parra Toro

    2011-01-01

    Full Text Available Al estudiar la fascinante diversidad socio-cultural brasileña solemos dejar de lado, injustificadamente, la considerable producción de los antropólogos brasileños. En este sentido, merece la pena detenerse en el controvertido libro de Karina Biondi, Junto e misturado, una etnografía do PCC, que podríamos traducir libremente como “Juntos y revueltos. Una etnografía del Primer Comando de la Capital”.

  16. TECHNIQUES FOR THE USE OF HOARE LOGIC IN PCC

    OpenAIRE

    2003-01-01

    Atualmente, a maioria dos programas para computadores é obtida através da WEB. Como muitas vezes a procedência são fontes desconhecidas, é preciso se certificar de que o código se comporta como o esperado. A solução ideal seria verificar o código contra uma especificação de políticas de segurança ,contudo, isso pode consumir muito tempo.Uma outra alternativa é fazer com que o próprio código prove ser seguro. O conceito de proof-carryng code (PCC)é baseado nessa...

  17. Selection and characterization of Euglena anabaena var. minor as a new candidate Euglena species for industrial application.

    Science.gov (United States)

    Suzuki, Kengo; Mitra, Sharbanee; Iwata, Osamu; Ishikawa, Takahiro; Kato, Sueo; Yamada, Koji

    2015-01-01

    Euglena gracilis is a microalgae used as a model organism. Recently, mass cultivation of this species has been achieved for industrial applications. The genus Euglena includes more than 200 species that share common useful features, but the potential industrial applications of other Euglena species have not been evaluated. Thus, we conducted a pilot screening study to identify other species that proliferate at a sufficiently rapid rate to be used for mass cultivation; we found that Euglena anabaena var. minor had a rapid growth rate. In addition, its cells accumulated more than 40% weight of carbohydrate, most of which is considered to be a euglenoid specific type of beta-1-3-glucan, paramylon. Carbohydrate is stored in E. anabaena var. minor cells during normal culture, whereas E. gracilis requires nitrogen limitation to facilitate paramylon accumulation. These results suggest the potential industrial application of E. anabaena var. minor.

  18. Functional role of PilA in iron acquisition in the cyanobacterium Synechocystis sp. PCC 6803.

    Directory of Open Access Journals (Sweden)

    Jacob J Lamb

    Full Text Available Cyanobacteria require large quantities of iron to maintain their photosynthetic machinery; however, in most environments iron is present in the form of insoluble iron oxides. Whether cyanobacteria can utilize these sources of iron, and the potential molecular mechanisms involved remains to be defined. There is increasing evidence that pili can facilitate electron donation to extracellular electron acceptors, like iron oxides in non-photosynthetic bacteria. In these organisms, the donation of electrons to iron oxides is thought to be crucial for maintaining respiration in the absence of oxygen. Our study investigates if PilA1 (major pilin protein may also provide a mechanism to convert insoluble ferric iron into soluble ferrous iron. Growth experiments supported by spectroscopic data of a strain deficient in pilA1 indicate that the presence of the pilA1 gene enhances the ability to grow on iron oxides. These observations suggest a novel function of PilA1 in cyanobacterial iron acquisition.

  19. Structural organisation of phycobilisomes from Synechocystis sp strain PCC6803 and their interaction with the membrane

    NARCIS (Netherlands)

    Arteni, Ana A.; Ajlani, Ghada; Boekema, Egbert J.

    2009-01-01

    In cyanobacteria, the harvesting of light energy for photosynthesis is mainly carried out by the phycobilisome a giant, multi-subunit pigment-protein complex. This complex is composed of heterodimeric phycobiliproteins that are assembled with the aid of linker polypeptides such that light absorption

  20. Protein Network Signatures Associated with Exogenous Biofuels Treatments in Cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Pei, Guangsheng; Chen, Lei; Wang, Jiangxin; Qiao, Jianjun; Zhang, Weiwen

    2014-01-01

    Although recognized as a promising microbial cell factory for producing biofuels, current productivity in cyanobacterial systems is low. To make the processes economically feasible, one of the hurdles, which need to be overcome is the low tolerance of hosts to toxic biofuels. Meanwhile, little information is available regarding the cellular responses to biofuels stress in cyanobacteria, which makes it challenging for tolerance engineering. Using large proteomic datasets of Synechocystis under various biofuels stress and environmental perturbation, a protein co-expression network was first constructed and then combined with the experimentally determined protein-protein interaction network. Proteins with statistically higher topological overlap in the integrated network were identified as common responsive proteins to both biofuels stress and environmental perturbations. In addition, a weighted gene co-expression network analysis was performed to distinguish unique responses to biofuels from those to environmental perturbations and to uncover metabolic modules and proteins uniquely associated with biofuels stress. The results showed that biofuel-specific proteins and modules were enriched in several functional categories, including photosynthesis, carbon fixation, and amino acid metabolism, which may represent potential key signatures for biofuels stress responses in Synechocystis. Network-based analysis allowed determination of the responses specifically related to biofuels stress, and the results constituted an important knowledge foundation for tolerance engineering against biofuels in Synechocystis.

  1. Engineered xylose utilization enhances bio-products productivity in the cyanobacterium Synechocystis sp. PCC 6803

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Tai-Chi; Xiong, Wei; Paddock, Troy; Carrieri, Damian; Chang, Ing-Feng; Chiu, Hui-Fen; Ungerer, Justin; Hank Juo, Suh-Hang; Maness, Pin-Ching; Yu, Jianping

    2015-07-01

    Hydrolysis of plant biomass generates a mixture of simple sugars that is particularly rich in glucose and xylose. Fermentation of the released sugars emits CO2 as byproduct due to metabolic inefficiencies. Therefore, the ability of a microbe to simultaneously convert biomass sugars and photosynthetically fix CO2 into target products is very desirable. In this work, the cyanobacterium, Synechocystis 6803, was engineered to grow on xylose in addition to glucose. Both the xylA (xylose isomerase) and xylB (xylulokinase) genes from Escherichia coli were required to confer xylose utilization, but a xylose-specific transporter was not required. Introducing xylAB into an ethylene-producing strain increased the rate of ethylene production in the presence of xylose. Additionally, introduction of xylAB into a glycogen-synthesis mutant enhanced production of keto acids. Moreover, isotopic tracer studies found that nearly half of the carbon in the excreted keto acids was derived from the engineered xylose metabolism, while the remainder was derived from CO2 fixation.

  2. Estudio de las glutamato sintasas de la cianobacteria Synechocystis sp. PCC 6803

    OpenAIRE

    Navarro Gómez, Francisco

    1996-01-01

    El objetivo de este trabajo fue, en principio, la caracterización del gen de la Fd-GOGAT de Synechocystis 6803, así como de la proteína correspondiente y el análisis de mutantes del mismo. El descubrimiento de dos enzimas con actividad glutamato sintasa en esta cianobacteria, llevó a un estudio de los genes correspondientes y a un análisis comparativo de los mismos, entre sí y con el resto de secuencias de glutamato sintasas disponibles. La obtención de mutantes simples de cada gen y de mut...

  3. Biogenesis and Ultrastructure of Carboxysomes from Wild Type and Mutants of Synechococcus sp. Strain PCC 7942.

    Science.gov (United States)

    Orus, M. I.; Rodriguez, M. L.; Martinez, F.; Marco, E.

    1995-04-01

    Immature inclusions representing three progressive steps of carboxysome biogenesis have been identified in Synechococcus during the period of adaptation to low-CO2 conditions: (a) ring-shaped structures, (b) electron-translucent inclusions with the shape of a carboxysome and the internal orderly arrangement of ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco) molecules, and (c) carboxysomes with an internal electron-translucent area, which seem to be the penultimate stage of carboxysome maturation. The ability to build up normal carboxysomes is impaired in three (M3, EK6, and D4) of four high-carbon-requiring mutants studied in this work. M3 and EK6 exhibit abundant immature electron-translucent carboxysomes but no mature ones. This finding supports the contention that an open reading frame located 7.5 kb upstream of the gene encoding the large subunit of Rubisco (altered in M3) is involved in the carboxysome composition and confirms the structural role of the small subunit of Rubisco (slightly modified in EK6) in the assembly of these structures. D4 shows few typical carboxysomes and frequent immature types, its genetic lesion affecting the apparently unrelated gene encoding a subunit of phosphoribosyl aminoamidazole carboxylase of the purine biosynthesis pathway. Revertants EK20 (EK6) and RK13 (D4) have normal carboxysomes, which means that the restoration of the ability to grow under low CO2 coincides with the proper assembling of these structures. N5, a transport mutant due to the alteration of the gene encoding subunit 2 of NADH dehydrogenase, shows an increase in the number and size of carboxysomes and frequent bar-shaped ones.

  4. Backbone dynamics of reduced plastocyanin from the cyanobacterium Anabaena variabilis: Regions involved in electron transfer have enhanced mobility

    DEFF Research Database (Denmark)

    Ma, L.X.; Hass, M.A.S.; Vierick, N.;

    2003-01-01

    The dynamics of the backbone of the electron-transfer protein plastocyanin from the cyanobacterium Anabaena variabilis were determined from the N-15 and C-13(alpha) R-1 and R-2) relaxation rates and steady-state [H-1]-N-15 and [H-1]-C-13 nuclear Overhauser effects (NOEs) using the model-free appr......The dynamics of the backbone of the electron-transfer protein plastocyanin from the cyanobacterium Anabaena variabilis were determined from the N-15 and C-13(alpha) R-1 and R-2) relaxation rates and steady-state [H-1]-N-15 and [H-1]-C-13 nuclear Overhauser effects (NOEs) using the model...

  5. Regulation of Nitrogenase Gene Expression by Transcript Stability in the Cyanobacterium Anabaena variabilis

    OpenAIRE

    Pratte, Brenda S.; Thiel, Teresa

    2014-01-01

    The nitrogenase gene cluster in cyanobacteria has been thought to comprise multiple operons; however, in Anabaena variabilis, the promoter for the first gene in the cluster, nifB1, appeared to be the primary promoter for the entire nif cluster. The structural genes nifHDK1 were the most abundant transcripts; however, their abundance was not controlled by an independent nifH1 promoter, but rather, by RNA processing, which produced a very stable nifH1 transcript and a moderately stable nifD1 tr...

  6. Bacterial Anabaena variabilis phenylalanine ammonia lyase: a biocatalyst with broad substrate specificity.

    Science.gov (United States)

    Lovelock, Sarah L; Turner, Nicholas J

    2014-10-15

    Phenylalanine ammonia lyases (PALs) catalyse the regio- and stereoselective hydroamination of cinnamic acid analogues to yield optically enriched α-amino acids. Herein, we demonstrate that a bacterial PAL from Anabaena variabilis (AvPAL) displays significantly higher activity towards a series of non-natural substrates than previously described eukaryotic PALs. Biotransformations performed on a preparative scale led to the synthesis of the 2-chloro- and 4-trifluoromethyl-phenylalanine derivatives in excellent ee, highlighting the enormous potential of bacterial PALs as biocatalysts for the synthesis of high value, non-natural amino acids.

  7. Drug-induced premature chromosome condensation (PCC) protocols: cytogenetic approaches in mitotic chromosome and interphase chromatin.

    Science.gov (United States)

    Gotoh, Eisuke

    2015-01-01

    Chromosome analysis is a fundamental technique which is used in wide areas of cytogenetic study including karyotyping species, hereditary diseases diagnosis, or chromosome biology study. Chromosomes are usually prepared from mitotic cells arrested by colcemid block protocol. However, obtaining mitotic chromosomes is often hampered under several circumstances. As a result, cytogenetic analysis will be sometimes difficult or even impossible in such cases. Premature chromosome condensation (PCC) (see Note 1) is an alternative method that has proved to be a unique and useful way in chromosome analysis. Former, PCC has been achieved following cell fusion method (cell-fusion PCC) mediated either by fusogenic viruses (e.g., Sendai virus) or cell fusion chemicals (e.g., polyethylene glycol), but the cell fusion PCC has several drawbacks. The novel drug-induced PCC using protein phosphatase inhibitors was introduced about 20 years ago. This method is much simpler and easier even than the conventional mitotic chromosome preparation protocol use with colcemid block and furthermore obtained PCC index (equivalent to mitotic index for metaphase chromosome) is usually much higher than colcemid block method. Moreover, this method allows the interphase chromatin to be condensed to visualize like mitotic chromosomes. Therefore drug-induced PCC has opened the way for chromosome analysis not only in metaphase chromosomes but also in interphase chromatin. The drug-induced PCC has thus proven the usefulness in cytogenetics and other cell biology fields. For this second edition version, updated modifications/changes are supplemented in Subheadings 2, 3, and 4, and a new section describing the application of PCC in chromosome science fields is added with citation of updated references.

  8. Identification of an Algae-lysing Bacterium of Anabaena flosaquae and Primary Research on Their Relationship%一株水华鱼腥藻溶藻菌的分离鉴定及菌藻关系初探

    Institute of Scientific and Technical Information of China (English)

    叶姜瑜; 钟以蓉; 俞岚; 李文娟

    2012-01-01

    [Objective] The aim was to explore the relationship between alage-lysing bacterium and Anabaena flosaquae so as to provide reference for the control of bloom. [Method] An algae-lysing bacterium strain named S7 was isolated from eu- trophic river. The lyric efficiency and performing mode of S7 strain to Anabaena flos- aquae was studied. Influence of different environmental factors and the relationship between S7 strain and Anabaena flosaquae was also studied, and then the bacteri- um strain was physiologically identified. [Result] More than 90% of Anabaena flos- aquae had been removed by 7 d when the volume ratio of medium to algae solu- tion was 30%, the pH was 9 and the temperature was 35 ℃. These results also showed that a mutual inhibit relationship existed between S7 strain and Anabaena flos-aquae. The S7 strain killed the algae by indirectly through certain lyric agents in absence of direct contact with the target but by secreting metabolites. Moreover, these lyric agents also had the thermostability. 16SrDNA sequence analysis showed that S7 strain belonged to Chryseobacterium sp. [Conclusion] The examined Poly-p proved that S7 strain is polyphosphate accumulating bacteria (PAOs) and has better lyric efficiency.%[目的]研究溶藻特性及菌藻关系,为进一步研究溶藻细菌对水华的治理作用提供帮助。[方法]从富营养化水体中分离得到一株有高效溶藻效果的菌株(S7),研究了其对水华鱼腥藻(Anabaenaflosaquae)的抑制效果、作用方式和不同环境因子对溶藻效果的影响,以及菌藻关系,并对菌株进行了菌体Poly—P的染色、革兰氏染色和分子鉴定。【结果]菌株投加量为藻液量的30%时,7d叶绿素a的去除率达到90%以上。pH为9,温度35℃下藻的去除率最高。S7菌株与水华鱼腥藻形成竞争共栖的生态关系,并通过分泌溶藻物质间接抑制水华鱼腥藻生长,且该物质具有一定的热稳定性。根据生

  9. Effects of lead accumulation on the Azolla caroliniana-Anabaena association.

    Science.gov (United States)

    Roberts, Anne E; Boylen, Charles W; Nierzwicki-Bauer, Sandra A

    2014-04-01

    The effect of lead accumulation on photopigment production, mineral nutrition, and Anabaena vegetative cell size and heterocyst formation in Azolla caroliniana was investigated. Plants were exposed to 0, 1, 5, 10, and 20 mg L(-1) lead acetate for ten days. Lead accumulation increased when plants were treated with higher lead concentrations. Results revealed a statistically significant decline in total chlorophyll, chlorophyll a, chlorophyll b, and carotenoids in 5, 10, and 20 mg Pb L(-1) treatment groups as compared to plants with 0 or 1 mg Pb L(-1) treatments. No statistically significant change in anthocyanin production was observed. Calcium, magnesium, and zinc concentrations in plants decreased in increasing treatment groups, whereas sodium and potassium concentrations increased. Nitrogen and carbon were also found to decrease in plant tissue. Anabaena vegetative cells decreased in size and heterocyst frequency declined rapidly in a Pb dose-dependent manner. These results indicate that, while A. caroliniana removes lead from aqueous solution, the heavy metal causes physiological and biochemical changes by impairing photosynthesis, changing mineral nutrition, and impeding the growth and formation of heterocysts of the symbiotic cyanobacteria that live within leaf cavities of the fronds.

  10. A role of Anabaena sensory rhodopsin transducer (ASRT) in photosensory transduction.

    Science.gov (United States)

    Kim, So Young; Yoon, Sa Ryong; Han, SongI; Yun, Yuna; Jung, Kwang-Hwan

    2014-08-01

    In 2003, Anabaena sensory rhodopsin (ASR), a membrane-bound light sensor protein, was discovered in cyanobacteria. Since then, a large number of functions have been described for ASR, based on protein biochemical and biophysical studies. However, no study has determined the in vivo mechanism of photosensory transduction for ASR and its transducer protein (ASRT). Here, we aimed to determine the role of ASRT in physiological photo-regulation. ASRT is known to be related to photochromism, because it regulates the expression of phycocyanin (cpc-gene) and phycoerythrocyanin (pec gene), two major proteins of the phycobilisome in cyanobacteria. By examining wild type and knockout mutant Anabaena cells, we showed that ASRT repressed the expression of these two genes. We also demonstrated physical interactions between ASRT, ASR, and the promoter regions of cpc, pec, kaiABC (circadian clock gene) and the asr operon, both in vitro and in vivo. Binding assays indicated that ASRT had different sites of interaction for binding to ASR and DNA promoter regions. ASRT also influenced the retinal re-isomerization rate in dark through a physical interaction with ASR, and it regulated reporter gene expression in vivo. These results suggested that ASRT relayed the photosignal from ASR and directly regulated gene expression.

  11. The Anabaena sensory rhodopsin transducer defines a novel superfamily of prokaryotic small-molecule binding domains

    Directory of Open Access Journals (Sweden)

    De Souza Robson F

    2009-08-01

    Full Text Available Abstract The Anabaena sensory rhodopsin transducer (ASRT is a small protein that has been claimed to function as a signaling molecule downstream of the cyanobacterial sensory rhodopsin. However, orthologs of ASRT have been detected in several bacteria that lack rhodopsin, raising questions about the generality of this function. Using sequence profile searches we show that ASRT defines a novel superfamily of β-sandwich fold domains. Through contextual inference based on domain architectures and predicted operons and structural analysis we present strong evidence that these domains bind small molecules, most probably sugars. We propose that the intracellular versions like ASRT probably participate as sensors that regulate a diverse range of sugar metabolism operons or even the light sensory behavior in Anabaena by binding sugars or related metabolites. We also show that one of the extracellular versions define a predicted sugar-binding structure in a novel cell-surface lipoprotein found across actinobacteria, including several pathogens such as Tropheryma, Actinomyces and Thermobifida. The analysis of this superfamily also provides new data to investigate the evolution of carbohydrate binding modes in β-sandwich domains with very different topologies. Reviewers: This article was reviewed by M. Madan Babu and Mark A. Ragan.

  12. Amino acid transport in taxonomically diverse cyanobacteria and identification of two genes encoding elements of a neutral amino acid permease putatively involved in recapture of leaked hydrophobic amino acids.

    Science.gov (United States)

    Montesinos, M L; Herrero, A; Flores, E

    1997-02-01

    The activities of uptake of thirteen 14C-labeled amino acids were determined in nine cyanobacteria, including the unicellular strains Synechococcus sp. strain PCC 7942 and Synechocystis sp. strain PCC 6803; the filamentous strain Pseudanabaena sp. strain PCC 6903, and the filamentous, heterocyst-forming strains Anabaena sp. strains PCC 7120 and PCC 7937; Nostoc sp. strains PCC 7413 and PCC 7107; Calothrix sp. strain PCC 7601 (which is a mutant unable to develop heterocysts); and Fischerella muscicola UTEX 1829. Amino acid transport mutants, selected as mutants resistant to some amino acid analogs, were isolated from the Anabaena, Nostoc, Calothrix, and Pseudanabaena strains. All of the tested cyanobacteria bear at least a neutral amino acid transport system, and some strains also bear transport systems specific for basic or acidic amino acids. Two genes, natA and natB, encoding elements (conserved component, NatA, and periplasmic binding protein, NatB) of an ABC-type permease for neutral amino acids were identified by insertional mutagenesis of strain PCC 6803 open reading frames from the recently published genomic DNA sequence of this cyanobacterium. DNA sequences homologous to natA and natB from strain PCC 6803 were detected by hybridization in eight cyanobacterial strains tested. Mutants unable to transport neutral amino acids, including natA and natB insertional mutants, accumulated in the extracellular medium a set of amino acids that always included Ala, Val, Phe, Ile, and Leu. A general role for a cyanobacterial neutral amino acid permease in recapture of hydrophobic amino acids leaked from the cells is suggested.

  13. Development and application of the PCC biodosimetry method in emergency preparedness

    Energy Technology Data Exchange (ETDEWEB)

    Stricklin, D. (Swedish Defence Research Agency, FOI (Sweden)); Lindholm, C. (Finnish Radiation and Nuclear Safety Authority, STUK (Finland)); Jaworska, A. (Norwegian Radiation Protection Authority, NRPA (Norway))

    2008-07-15

    A method for biological assessment of radiation dose for specific application in emergency preparedness was developed. Premature chromosome condensation (PCC) was investigated to provide a potentially faster means of analysis and the ability to assess higher doses than with the dicentric assay which is routinely applied in biodosimetry today. A review of existing methods was made, followed by experiments determine optimal assay conditions, and evaluations to determination of optimal conditions and the most appropriate endpoints for analyses. Twelve different experimental conditions were examined with four different evaluation approaches. Aspects during optimization such as practicality, speed, and reliability were considered. The conclusion from these studies was a PCC protocol utilizing okadaic acid for induction of PCC cells in stimulated lymphocytes but without the use of colcemid for metaphase arrest with the subsequent evaluation of ring chromosomes. Well-defined criteria were established for evaluation of PCC cells and ring chromosome aberrations. An inter-calibration was made by comparing assessment of ring chromosomes between all three laboratories. Agreement was made to count only rings with observable open spaces or large, obvious rings without open spaces. Finally a dose response curve for the PCC method was prepared and a comparison of the PCC method to the traditional dicentric assay in triage mode was made. The triage method requires a minimal number of evaluations so that categorization of high, medium and low doses may be made in an emergency situation where large numbers of people should be evaluated. The comparison of the PCC method with the dicentric assay triage method indicated that the PCC assay performed superior to the dicentric assay for evaluation of samples at higher doses, however, the dicentric assay appeared to provide more accurate dose assessment at lower doses. This project suggests a PCC assay method for biological dose estimates

  14. Fundamental Frequency Estimation of the Speech Signal Compressed by MP3 Algorithm Using PCC Interpolation

    Directory of Open Access Journals (Sweden)

    MILIVOJEVIC, Z. N.

    2010-02-01

    Full Text Available In this paper the fundamental frequency estimation results of the MP3 modeled speech signal are analyzed. The estimation of the fundamental frequency was performed by the Picking-Peaks algorithm with the implemented Parametric Cubic Convolution (PCC interpolation. The efficiency of PCC was tested for Catmull-Rom, Greville and Greville two-parametric kernel. Depending on MSE, a window that gives optimal results was chosen.

  15. Premature chromosome condensation (PCC) assay for dose assessment in mass casualty accidents.

    Science.gov (United States)

    Lindholm, Carita; Stricklin, Daniela; Jaworska, Alicja; Koivistoinen, Armi; Paile, Wendla; Arvidsson, Eva; Deperas-Standylo, Joanna; Wojcik, Andrzej

    2010-01-01

    The study was undertaken to establish a dose calibration curve for a practical PCC ring assay and to apply it in a simulated mass casualty accident. The PCC assay was validated against the conventional dicentric assay. A linear relationship was established for PCC rings after (60)Co gamma irradiation with doses up to 20 Gy. In the simulated accident experiment, 62 blood samples were analyzed with both the PCC ring assay and the conventional dicentric assay, applying a triage approach. Samples received various uniform and non-uniform (10-40% partial-body) irradiations up to doses of 13 Gy. The results indicated that both assays yielded good dose estimates for the whole-body exposure scenario, although in the lower-dose range (0-6 Gy) dicentric scoring resulted in more accurate whole-body estimates, whereas PCC rings were better in the high-dose range (>6 Gy). Neither assay was successful in identifying partial-body exposures, most likely due to the low numbers of cells scored in the triage mode. In conclusion, the study confirmed that the PCC ring assay is suitable for use as a biodosimeter after whole-body exposure to high doses of radiation. However, there are limitations for its use in the triage of people exposed to high, partial-body doses.

  16. Variety of DNA Replication Activity Among Cyanobacteria Correlates with Distinct Respiration Activity in the Dark.

    Science.gov (United States)

    Ohbayashi, Ryudo; Yamamoto, Jun-Ya; Watanabe, Satoru; Kanesaki, Yu; Chibazakura, Taku; Miyagishima, Shin-Ya; Yoshikawa, Hirofumi

    2016-11-10

    Cyanobacteria exhibit light-dependent cell growth since most of their cellular energy is obtained by photosynthesis. In Synechococcus elongatus PCC 7942, one of the model cyanobacteria, DNA replication depends on photosynthetic electron transport. However, the critical signal for the regulatory mechanism of DNA replication has not been identified. In addition, conservation of this regulatory mechanism has not been investigated among cyanobacteria. To understand this regulatory signal and its dependence on light, we examined the regulation of DNA replication under both light and dark conditions among three model cyanobacteria, S. elongatus PCC 7942, Synechocystis sp. PCC 6803 and Anabaena sp. PCC 7120. Interestingly, DNA replication activity in Synechocystis and Anabaena was retained when cells were transferred to the dark, although it was drastically decreased in S. elongatus. Glycogen metabolism and respiration were higher in Synechocystis and Anabaena than in S. elongatus in the dark. Moreover, DNA replication activity in Synechocystis and Anabaena was reduced to the same level as that in S. elongatus by inhibition of respiratory electron transport after transfer to the dark. These results demonstrate that there is disparity in DNA replication occurring in the dark among cyanobacteria, which is caused by the difference in activity of respiratory electron transport.

  17. 中国鱼腥藻属的两个新记录种%Two newly recorded species of Anabaena(Nostocales, Cyanobacteria) in China

    Institute of Scientific and Technical Information of China (English)

    李守淳; 柴文波; 郑洪萍; 耿军灵; 李仁辉

    2012-01-01

    迄今为止,全球范围共报道出100多种鱼腥藻,中国记录报道的仅有50余种,但有些种类的描述仍较模糊.最近在福建、浙江等地进行野外调查时,发现了多种丝状蓝藻.其中就有2种鱼腥藻在中国尚未报道:威格鱼腥藻( Anabaena viguieri Denis et Frémy 1923)和史密斯鱼腥藻(Anabaena smithii( Komárek)Watanabe 1992).%So far, more than 100 species of genus Anabaena have been recorded in the world, and about 50 taxa were described in China. During our recent field investigations for water-bloom forming cyanobacteria in China, several filamentous cyanobacterial species were examined in the samples. In this study, we demonstrated that two Anabaena species as Anabaena viguieri Denis et Fremy 1923 and Anabaena smithii (Komdrek) Watanabe 1992, had never been reported in China, and they are newly described and discussed in the present study.

  18. Genetic Basis for Geosmin Production by the Water Bloom-Forming Cyanobacterium, Anabaena ucrainica

    Directory of Open Access Journals (Sweden)

    Zhongjie Wang

    2014-12-01

    Full Text Available Geosmin is a common, musty-smelling sesquiterpene, principally produced by cyanobacteria. Anabaena ucrainica (Schhorb. Watanabe, a water bloom-forming cyanobacterium, is the geosmin producer responsible for odor problems in Dianchi and Erhai lakes in China. In this study, the geosmin synthase gene (geo of A. ucrainica and its flanking regions were identified and cloned by polymerase chain reaction (PCR and genome walking. The geo gene was found to be located in a transcription unit with two cyclic nucleotide-binding protein genes (cnb. The two cnb genes were highly similar and were predicted members of the cyclic adenosine monophosphate (cAMP receptor protein/fumarate nitrate reductase regulator (Crp–Fnr family. Phylogenetic and evolutionary analyses implied that the evolution of the geosmin genes involved a horizontal gene transfer process in cyanobacteria. These genes showed a close relationship to 2-methylisoborneol genes in origin and evolution.

  19. Na(+) regulation by combined nitrogen in Azolla pinnata-Anabaena azollae symbiotic association during salt toxicity.

    Science.gov (United States)

    Singh, Satya S; Singh, Santosh K; Mishra, Arun K

    2008-01-01

    To study the regulation of Na(+) ion by combined-N sources in Azolla pinnata-Anabaena azollae, Na(+) influx, intracellular Na(+) and Na(+) efflux were investigated in the presence of different N-sources (N(2), NH(4)(+), NO(3)(-) and urea) and various NaCl concentrations. Sodium influx by Azolla pinnata fronds was minimum in the presence of NO(3)(-). Almost identical levels of intracellular sodium, although less than N(2) and NH(4)(+) incubated fronds were observed in the presence of NO(3)(-) and urea. Efflux of sodium was minimum in urea and NO(3)(-) grown fronds. A low residual sodium was observed in the fronds incubated in NO(3)(-) and urea supplemented media. Results suggest that nitrate and urea curtailed the entry of sodium, reduced salt toxicity maximally by maintaining the minimum level of sodium and also conserved energy due to slow influx and efflux of Na(+) within the fronds during salt shock and the process of adaptation.

  20. EXPRESSION OF THE GEOSMIN SYNTHASE GENE IN THE CYANOBACTERIUM ANABAENA CIRCINALIS AWQC318(1).

    Science.gov (United States)

    Giglio, Steven; Saint, Christopher P; Monis, Paul T

    2011-12-01

    The occurrence of taste and odor episodes attributed to geosmin continues to trouble water utilities worldwide, and only recently have advances been made in our fundamental understanding of the biochemical and genetic mechanisms responsible for the production of geosmin in microorganisms. For the first time, we have examined the expression of the geosmin synthase gene and corresponding geosmin production by Anabaena circinalis Rabenh. ex Bornet et Flahault AWQC318 under conditions of continuous light illumination and the removal of light as a stimulus and demonstrate that the expression of geosmin synthase appears to be constitutive under these conditions. The decrease in geosmin synthase transcription post maximum cell numbers and stationary phase suggests that a decrease in isoprenoid synthesis may occur before a decrease in the transcription of ribosomal units as the process of cell death is initiated.

  1. Purification and some properties of Fe protein of nitrogenase from. Anabaena cylindrica

    Science.gov (United States)

    Du, Daixian; Lin, Huimin; He, Zhenrong; Dai, Lingfen; Xin, Wusheng; Li, Shanghao

    1990-12-01

    The Fe protein of Anabaena cylindrica was first separated and purified by chromatography through DEAE-cellulose columns then by gel electrophoresis. The specific activity was up to 142.46 nmol C2H4/mg protein · min. It was homogeneous as shown by 1) a single band in the gel electrophorogram; 2) absence of Mo and tryptophan; 3) content of about 3.4 atoms of Fe per mole protein. The molecular weight of the Fe protein of A. cylindrica was about 61,000 daltons as estimated by SDS-gel electrophoresis and calculated from the amino acid composition. The residues of aspartate and glutamate were about 2.6 times that of arginine and lysine in the Fe protein. Crossing Fe protein of A. cylindrica with Mo-Fe protein of Azotobacter vinelandii gave positive result. The reciprocal crossing also showed activity.

  2. The electronic structure of the neutral isoalloxazine semiquinone within Anabaena flavodoxin: New insights from HYSCORE experiments

    Science.gov (United States)

    Martínez, Jesús I.; Alonso, Pablo J.; Medina, Milagros

    2012-05-01

    A complete study of Anabaena flavodoxin in the neutral semiquinone state by means of the EPR pulse technique HYSCORE is here presented. The results provide new information about the hyperfine interactions of the unpaired electronic spin and the nuclei in the isoalloxazine ring. This allows a better knowledge of the electronic structure of the neutral flavin radical within the protein. Combination of these results with other previously obtained by using other EPR related techniques allowed producing a very precise mapping of the flavin spin distribution in the neutral semiquinone state. This information can be very useful for determining the relationship between the electronic structure and mechanisms in flavoproteins. An experimental protocol for measuring the electronic structure details available to date is suggested.

  3. Casting a net: fibres produced by Microcystis sp. in field and laboratory populations.

    Science.gov (United States)

    Harel, Moshe; Weiss, Gad; Daniel, Einat; Wilenz, Avraham; Hadas, Ora; Sukenik, Assaf; Sedmak, Bojan; Dittmann, Elke; Braun, Sergei; Kaplan, Aaron

    2012-06-01

    The reasons for the apparent dominance of the toxic cyanobacterium Microcystis sp., reflected by its massive blooms in many fresh water bodies, are poorly understood. We show that in addition to a large array of secondary metabolites, some of which are toxic to eukaryotes, Microcystis sp. secretes large amounts of fibrous exopolysaccharides that form extremely long fibres several millimetres in length. This phenomenon was detected in field and laboratory cultures of various Microcystis strains. In addition, we have identified and characterized three of the proteins associated with the fibres and the genes encoding them in Microcystis sp. PCC 7806 but were unable to completely delete them from its genome. Phylogenetic analysis of the most abundant one, designated IPF-469, showed its presence only in cyanobacteria. Its closest relatives were detected in Synechocystis sp. PCC 6803 and in Cyanothece sp. strains; in the latter the genomic organization of the IPF-469 was highly conserved. IPF-469 and the other two proteins identified here, a haloperoxidase and a haemolysin-type calcium-binding protein, may be part of the fibres secretion pathway. The biological role of the fibres in Microcystis sp. is discussed.

  4. PCC-ring induction in human lymphocytes exposed to gamma and neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Lamadrid B, A.I.; Garcia L, O. [CPHR, Calle 20 No. 4113 e/41 y 47, Playa, La Habana 11300 (Cuba); Delbos, M.; Voisin, P.; Roy, L. [Institut de Radioprotection et de Surete Nucleaire, BP 17, 92262 Fontenay-aux-Roses (France)]. e-mail: ana@cphr.edu.cu

    2006-07-01

    Dose-effect curves for dose assessment in Gamma and neutron overexposures to high doses are presented in this paper for the first time in literature. The relationships were obtained by plotting the Premature Chromosome Condensation -rings (PCC-R) frequencies in PCC Iymphocytes obtained by chemical induction with Calyculin A in vitro, with radiation doses between 5 to 25 Gy. For the elaboration of these curves 9 676 PCC cells in Gl G2 and M stages were analyzed. The results were fitted to a lineal quadratic model in Gamma irradiation. For neutron irradiation the data was fitted to a lineal quadratic model up to 10 Gy and then a markedly cell cycle arrest and saturation was observed. These curves are of particular interest for victims exposed to doses exceeding 5 Gy where it is always very difficult to estimate a dose using the conventional technique. (Author)

  5. Case Report: Apixaban-Associated Gluteal Artery Extravasation Reversed With PCC3 Without FFP.

    Science.gov (United States)

    Denetclaw, Tina Harrach; Tam, Jacqueline; Arias, Victor; Kim, Rachel; Martin, Christopher

    2016-08-01

    Apixaban, an oral factor Xa inhibitor, has no commercially available assay to measure its activity and no specific antidote. To date, recommendations for managing bleeding associated with apixaban are based on studies with animal models and healthy volunteers (who do not have identified thrombogenic risk factors) and expert opinion. No clinical experience has been published in the literature. Ideally, apixaban would be reversed sufficiently to stop a perilous bleed without producing more thrombogenic risk than the patients' underlying risk factors. Three-factor prothrombin complex concentrate (PCC3) is the least thrombogenic among the suggested reversal agents. Fresh frozen plasma (FFP) is sometimes recommended to add to PCC3, but it adds considerable volume. We describe successful management of an active left gluteal arterial extravasation due to trauma and associated apixaban, in a patient with aortic stenosis and atrial fibrillation, by administration of PCC3 alone, without the added volume of FFP.

  6. Construction of dnaA Temperature-Sensitive Mutants of Heterocyst Differentiated Cyanobacterium%异形胞分化蓝细菌dnaA温度敏感型突变体的构建

    Institute of Scientific and Technical Information of China (English)

    魏新元; 丑敏霞; 闻盼盼

    2010-01-01

    以能分化异形胞的蓝细菌(Anabaena sp.PCC 7120)为材料,采用重组PCR在体外对控制DNA复制起始的dnaA基因进行定点突变后克隆到整合质粒中,再通过三亲本杂交将整合质粒转移到Anabaena PCC 7120中,以分离和筛选温度敏感型突变体.结果成功获得Anabaena PCC 7120 dnaA高温敏感性突变体.研究表明,利用重组PCR技术可在体外实现对Anabaena PCC 7120的dnaA的定点突变,并可通过同源重组双交换成功实行整合质粒中突变基因对野生型基因的置换,使突变基因插入到细胞染色体中,进而成功构建温度敏感型突变菌株.

  7. Response of cyanobacteria to low atmosphere pressure

    Science.gov (United States)

    Qin, Lifeng; Ai, Weidang; Guo, Shuangsheng; Tang, Yongkang; Yu, Qingni; Shen, Yunze; Ren, Jin

    Maintaining a low pressure environment would reduce the technological complexity and constructed cost of future lunar base. To estimate the effect of hypobaric of controlled ecological life support system in lunar base on terrestrial life, cyanobacteria was used as the model to exam the response of growth, morphology, physiology to it. The decrease of atmosphere pressure from 100 KPa to 50 KPa reducing the growth rates of Microcystis aeruginosa, Merismopedia.sp, Anabaena sp. PCC 7120, Anabaena Hos-aquae, the chlorophyll a content in Microcystis aeruginosa, Merismopedia.sp, Anabaena Hos-aquae, the carotenoid content in Microcystis aeruginosa, Merismopedia.sp and Anabaena sp. PCC 7120, the phycocyanin content in Microcystis aeruginosa. This study explored the biological characteristics of the cyanobacteria under low pressure condition, which aimed at understanding the response of the earth's life to environment for the future moon base, the results enrich the research contents of the lunar biology and may be referred for the research of other terrestrial life, such as human, plant, microbe and animal living in life support system of lunar base.

  8. Biosorption of cadmium and lead from aqueous solution by fresh water alga Anabaena sphaerica biomass

    Directory of Open Access Journals (Sweden)

    Azza M. Abdel -Aty

    2013-07-01

    Full Text Available The present work represents the biosorption of Cd(II and Pb(II from aqueous solution onto the biomass of the blue green alga Anabaena sphaerica as a function of pH, biosorbent dosage, contact time, and initial metal ion concentrations. Freundlich, Langmuir, and Dubinin–Radushkevich (D–R models were applied to describe the biosorption isotherm of both metals by A. sphaerica biomass. The biosorption isotherms studies indicated that the biosorption of Cd(II and Pb(II follows the Langmuir and Freundlish models. The maximum biosorption capacities (qmax were 111.1 and 121.95 mg/g, respectively, at the optimum conditions for each metal. From the D–R isotherm model, the mean free energy was calculated to be 11.7 and 14.3 kJ/mol indicating that the biosorption mechanism of Cd(II and Pb(II by A. sphaerica was chemisorption. The FTIR analysis for surface function group of algal biomass revealed the existence of amino, carboxyl, hydroxyl, and carbonyl groups, which are responsible for the biosorption of Cd(II and Pb(II. The results suggested that the biomass of A. sphaerica is an extremely efficient biosorbent for the removal of Cd(II and Pb(II from aqueous solutions.

  9. Modeling culture profiles of the heterocystous N2-fixing cyanobacterium Anabaena flos-aquae.

    Science.gov (United States)

    Pinzon, Neissa M; Ju, Lu-Kwang

    2006-01-01

    Heterocyst differentiation is a unique feature of nitrogen-fixing cyanobacteria, potentially important for photobiological hydrogen production. Despite the significant advances in genetic investigation on heterocyst differentiation, there were no quantitative culture-level models that describe the effects of cellular activities and cultivation conditions on the heterocyst differentiation. Such a model was developed in this study, incorporating photosynthetic growth of vegetative cells, heterocyst differentiation, self-shading effect on light penetration, and nitrogen fixation. The model parameters were determined by fitting experimental results from the growth of the heterocystous cyanobacterium Anabaena flos-aquae CCAP 1403/13f in media without and with different nitrate concentrations and under continuous illumination of white light at different light intensities (2, 5, 10, 17, 20 and 50 microE m-2 s-1). The model describes the experimental profiles well and gives reasonable predictions even for the transition of growth from that on external N source to that via nitrogen fixation, responding to the change in external N concentrations. The significance and implications of the best-fit values of the model parameters are discussed.

  10. Characterization of Anabaena cylindrica Solution System Using Synchronous- Scan Fluorescence Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    LIU Xian-li; DENG Nan-sheng; TAO Shu

    2005-01-01

    The characterization of the algae Anabaena cylindrica solu tion with Fe (Ⅲ) was investigated using fluorescence emission and syn chronous-scan spectroscopy. The ranges of concentrations of algae and Fe (Ⅲ) in aqueous solutions were 5. 0 × 107-2. 5 × 108 cell/L and 10-60μmol/L, respectively. The effective characterization method used was synchronous-scan fluorescence spectroscopy (SFS). The wavelength difference (△λ) of 90 nm was maintained between excitation wavelength (λex) and emission wavelength(λem ). The peak was observed at about λex 236 nm/λem 326 nm for synchronous-scan fluorescence spectroscopy. The fluorescence quenching in system of algae-Fe( Ⅲ)-HA was studied using synchronous-scan spectroscopy for the first time. Fe(Ⅲ) was clearly the effective quencher. The relationship between I0 / I (quenching efficiency)and c (concentration of Fe (Ⅲ) added) was a linear correlation for the al gae solution with Fe(Ⅲ). Also, Aldrich humic acid (HA) was found to be an effective quencher.

  11. Accelerating of Pink Pigment Excretion from Cyanobacterium Oscillatoria by Co-Cultivation with Anabaena

    Directory of Open Access Journals (Sweden)

    DWI SUSILANINGSIH

    2007-03-01

    Full Text Available The freshwater cyanobacterium Oscillatoria BTCC/A 0004 excretes pink pigment containing lipoproteins with molecular weights of about 10 kDa. This pigment has surfactant properties with strong emulsification activity toward several hydrocarbons. This extracellular metabolite was suspected as toxin or allelochemical in their habitat. In this study, I investigated the effect of co-cultivation of Oscillatoria with Anabaena variabilis on the pigment excretion to explore the physiological roles of this pigment in its natural environment. The dead or viable cells and medium of A. variabilis were added into Oscillatoria cultures. Results showed that co-cultivation of free viable cells of A. variabilis enhanced the excretion of pigment without effect on the cell growth. Co-cultivation with viable cells in separated method and dead cells did not influenced the pigment production. The addition of A. variabilis medium was slightly increased the excretion of the pigment. Those results indicated that direct contact with A. variabilis caused Oscillatoria released a certain signaling compound.

  12. The cultivation of Anabaena variabilis in a bubble column operating under bubbly and slug flows.

    Science.gov (United States)

    Yoon, Jong Hyun; Choi, Shin Sik; Park, Tai Hyun

    2012-04-01

    In a bubble column reactor with an inner diameter of 6cm and a height of 63cm for the culture of cyanobacteria two different shapes of bubbles can be generated, resulting in bubbly flow or slug flow. Growth of Anabaena variabilis under slug flow (1.9g/l/day) was 1.73 times higher than that under bubbly flow (1.1g/l/day) when the specific irradiation rate was maintained above 10μmol/s/g dry cell. Although a stepwise increase in superficial gas velocity enhanced the average cell growth rate under bubbly flow by 1.57 times, the average cell growth rate during the deceleration phase under bubbly flow (1.98g/l/day) was 0.61 times smaller than that under slug flow (3.22g/l/day). These results demonstrate that the bubble shape in the slug flow was advantageous in regards to the radial circulation of cells.

  13. Research on PCC Control Method for Ribbon-free Random Winding

    Institute of Scientific and Technical Information of China (English)

    WEI Jian; WANG Ming-hong; TANG Yi-fan; LU Wen-hua; WU Wen-ying

    2004-01-01

    Based on analyzing the overlap appearance of random winding, basic principles of ribbon-free random winding and parametric selections for anti-overlap are discussed. The ribbon-free random winding control system and its related hardware construction as well as its software design are introduced by applying PCC technology to high speed spinning machine of synthetic filament.

  14. Genome-wide responses of Synechocystis PCC6803 to nitrogen deprivation

    NARCIS (Netherlands)

    Krasikov, V.; Aguirre von Wobeser, E.; Huisman, J.; Ibelings, B; Matthijs, H.C.P.; Matthijs, H. C. P.

    2005-01-01

    Genome-wide responses of Synechocystis PCC6803 to nitrogen deprivation Vladimir Krasikov1, Eneas Aguirre-von-Wobeser1, Jef Huisman1, Bas Ibelings2, Hans C.P. Matthijs1 1Universiteit van Amsterdam, Amsterdam, the Netherlands; 2Netherlands Institute of Ecology, Limnological Institute, Nieuwersluis, th

  15. Effect of light on the content of photosynthetically active pigments in plants. Pt. 4. Chromatic adaption in blue-green algae Anabaena cylindrica and A. variabilis

    Energy Technology Data Exchange (ETDEWEB)

    Czeczuga, B.

    1986-07-15

    The photosynthetic pigments (chlorophyll a, carotenoids and phycobiliprotein pigments) of two species of the genus Anabaena grown in white, red, yellow, green and blue light were examined. The highest concentration of the cells was observed in the sample with red light in case of the both species, and the smallest with blue light. The biggest amounts of chlorophyll a and carotenoids were included in the cells of samples with the yellow and the smallest in case of the red light. The ratio of two phycobiliproteins is as follows: - in Anabaena cylindrica: the highest amount of C-phycocyanin in the cells was observed in the case of the red light, and C-phycoerytherin was found in the blue light; - in Anabaena variabiles: the highest amount of C-phycocyanien in the cells was found in case of the yellow light, and allophycocyanin was found in the blue light.

  16. Study on the Salt tolerance and Mechanism of Nitrogen-Fixing Cyanobacteria Nostoc Commune and Anabaena Azotica Ley%固氮蓝藻Nostoc commune和Anabaena azotica Ley耐盐性及机理研究

    Institute of Scientific and Technical Information of China (English)

    张巍; 冯玉杰

    2008-01-01

    文章考察了两种固氮蓝藻Nostoc commune(地木耳)和Anabaena azotica Ley(固氮鱼腥藻)在不同浓度Na2CO3(0.2×10-4~1.8×10-4 g/ml)的BG11o培养基中的耐盐性.分别测定了两种固氮蓝藻在不同培养阶段的叶绿素a含量、胞外多糖含量、氨基酸含量和固氮酶活性的变化.研究结果表明两种固氮蓝藻都能在Na2CO3盐胁迫条件下生长,且随着Na2CO3盐胁迫性增加,两种蓝藻的叶绿素a含量、胞外多糖含量、氨基酸含量和固氮酶活性都呈现先增加后减少的趋势;而随着培养天数的增加,两种藻类叶绿素a的变化曲线与微生物的生长曲线很相似,胞外多糖和氨基酸的增长和叶绿素a的增长是同步的,其中,Anabaena azotica Ley的固氮酶活性在培养到21天时达到最大值,Nostoc commune的固氮酶活性在培养到28天时达到最大值;比较而言Anabaena azotica Ley的耐盐性好于Nostoc commune的耐盐性,固氮能力也高于Nostoc commune.

  17. Highly plastic genome of Microcystis aeruginosa PCC 7806, a ubiquitous toxic freshwater cyanobacterium

    Directory of Open Access Journals (Sweden)

    Latifi Amel

    2008-06-01

    Full Text Available Abstract Background The colonial cyanobacterium Microcystis proliferates in a wide range of freshwater ecosystems and is exposed to changing environmental factors during its life cycle. Microcystis blooms are often toxic, potentially fatal to animals and humans, and may cause environmental problems. There has been little investigation of the genomics of these cyanobacteria. Results Deciphering the 5,172,804 bp sequence of Microcystis aeruginosa PCC 7806 has revealed the high plasticity of its genome: 11.7% DNA repeats containing more than 1,000 bases, 6.8% putative transposases and 21 putative restriction enzymes. Compared to the genomes of other cyanobacterial lineages, strain PCC 7806 contains a large number of atypical genes that may have been acquired by lateral transfers. Metabolic pathways, such as fermentation and a methionine salvage pathway, have been identified, as have genes for programmed cell death that may be related to the rapid disappearance of Microcystis blooms in nature. Analysis of the PCC 7806 genome also reveals striking novel biosynthetic features that might help to elucidate the ecological impact of secondary metabolites and lead to the discovery of novel metabolites for new biotechnological applications. M. aeruginosa and other large cyanobacterial genomes exhibit a rapid loss of synteny in contrast to other microbial genomes. Conclusion Microcystis aeruginosa PCC 7806 appears to have adopted an evolutionary strategy relying on unusual genome plasticity to adapt to eutrophic freshwater ecosystems, a property shared by another strain of M. aeruginosa (NIES-843. Comparisons of the genomes of PCC 7806 and other cyanobacterial strains indicate that a similar strategy may have also been used by the marine strain Crocosphaera watsonii WH8501 to adapt to other ecological niches, such as oligotrophic open oceans.

  18. Protein (Cyanobacteria): 29524 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available _0321 Synechocystis sp. PCC 6803 substr. PCC-P MLLITIAFLRFYDQTDFEFLGLVANPRQWSNGFTVAALLATLANFGVEWNRRNRETNRLAQEAQRRVEEGQRRMAQERADESRRAEERERQIARTRIETRCRIAEIQFQLDPSDRNRRLLREALALLAEYGDLFS ...

  19. Protein (Cyanobacteria): 131052 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available N_0603 Synechocystis sp. PCC 6803 substr. PCC-N MTTNNSTLLDTIQQGFRITVGATASLVETLQDPQKRQGTFQDLQQEWDQRASQWAQKGTTTETEARQYVDQLLAQWRQSLPNPLSKTTATGSNNIIDFATAKRELDRLTEEIATLKGELAQDKPGTEG ...

  20. Protein (Cyanobacteria): 435835 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available CP_0098 Synechocystis sp. PCC 6803 substr. PCC-P MASTPIQSEARTDLEPSFVIPLVLLFGAIPIFFLQMWVGLAIAVFGVFLMVQTAIIKLSFTATALEVYRGSKLIRSFPYTEWQNWRIFWEPAPILFYFKEVKSIHFLPIIFDPGTLKACLERHCPLQSLRAE ...

  1. Protein (Cyanobacteria): 435834 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available CN_0098 Synechocystis sp. PCC 6803 substr. PCC-N MASTPIQSEARTDLEPSFVIPLVLLFGAIPIFFLQMWVGLAIAVFGVFLMVQTAIIKLSFTATALEVYRGSKLIRSFPYTEWQNWRIFWEPAPILFYFKEVKSIHFLPIIFDPGTLKACLERHCPLQSLRAE ...

  2. Protein (Cyanobacteria): 335166 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available TLSAFWGDSKAKLLSGEHPLTGEELIDCAKANVSKGVATAAQLCGFASDLDRFRTALKDTMAEMGIEDESLQKLLSS ... ...protein PCC7418_1513 Halothece sp. PCC 7418 MGKSTQAHLERTINKDQPLEARQQELKKMNYYMGAKLLEVGVDPQSPEILYRWSIKTQGNQQFC

  3. Protein (Cyanobacteria): 102765 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available otein PCC7418_3015 Halothece sp. PCC 7418 MKKIVLDAGPLIGLFYAKDTYHNDCVRGFEQLTQQKTILLTPIPILFEVYKWLLQLTQPAIAHSTLKVMQESLYLLPLEQPDFEEIQDMVTKLPQWQGSLEDATVVFTALRYHSPVWTYNFRDFSIFKTLEFWTPEPK ...

  4. SP. Pescado

    Directory of Open Access Journals (Sweden)

    Renato Gendre

    2003-12-01

    Full Text Available Nell'occhiello di un articolo dal titolo Il Peru dei de[Jini rosa e de/la grande pioggia si legge: "da una partenza  in aereo al «pescado»  che ti  sfamera."1 Questa parola spagnola, giustamente chiusa tra caporali, a noi pare molto interes­ sante, perche, nonostante l'apparenza, non ha nulla da spartire sotto i1 profilo se­ mantico con l'it. pescato. lnfatti, tutti i piu importanti dizionari della lingua italiana, di ieri e di oggi, etimologici e non 2, registrano  accanto a pescata,  ii lemma pescato, 3 ma lo spiegano come "quantita di pesce catturato nel corso di una battuta o di una stagione di pesca",4 mentre lo sp. pescado  indica i1 "pesce (solo nel senso di: pesGe pescato da mangiare [...]".s

  5. Bioremoval of heavy metals and nutrients from sewage plant by Anabaena oryzae and Cyanosarcina fontana.

    Science.gov (United States)

    Fawzy, Mustafa A; Issa, Ahmed A

    2016-01-01

    The present study demonstrated the growth of two species of cyanobacteria on wastewater isolated from sewage plant in Aswan, Egypt. We evaluated their efficiency for eliminating nitrogen, phosphorus, chemical oxygen demand (COD) and heavy metals (Fe(2+), Pb(2+), Cu(2+), and Mn(2+)). The growth of Cyanosarcina fontana has supported wastewater as a growth medium than Anabaena oryzae compared to standard medium. The nutrients concentration such as COD, NO3-N and PO4-P were decreased by the growth of A. oryzae and C. fontana in the wastewater after primary settling and centrate. However, the reduction of COD was less efficient than the other nutrients. The reduction percentage of COD, NO3-N and PO4-P reached 39.3, 84.1 and 90.7% as well as 54.6, 83.1, and 89.8%, in cultures of A. oryzae and C. fontana grown in the wastewater after primary settling, respectively. The reduction amounted to 10.1, 76.8, and 63.0% by A. oryzae and 43.2, 62.1, and 74.8% by C. fontana, grown in the centrate, respectively. Cyanobacteria species have the ability to accumulate the heavy metals from the wastewater to level far than the exceeding metal level in the water. Whereas, the heavy metals biosorption performance of C. fontana was higher in accumulating Fe(2+) (93.95%), Pb(2+) (81.21%), Cu(2+) (63.9%), and Mn(2+) (48.49%) compared to A. oryzae. The biosorption ability is dependent on the nature of the adsorbent studied and the type of wastewater treated. Therefore, removal of heavy metals and nutrients by the tested algae is strongly recommended as a powerful technique for the removal of pollutants from wastewater.

  6. Evaluation of conversion efficiency of light to hydrogen energy by Anabaena variabilis

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jong Hyun; Hae Shin, Ji; Park, Tai Hyun [School of Chemical and Biological Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Kim, Mi-Sun [Biomass Research Team, Korea Institute of Energy Research, Daejeon 305-343 (Korea, Republic of); Jun Sim, Sang [Department of Chemical Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2006-05-15

    Cyanobacteria provide an efficient system for producing H{sub 2} from water using solar energy. The energy conversion efficiency can be defined by the ratio of H{sub 2} produced to the light energy absorbed. An IR and opalescent plate method was used to measure the light energy absorbed. Since cyanobacteria absorb light in the visible range but not in the infrared range, the net amount of light energy absorbed by the cells can be estimated by measuring the IR and visible light intensities transmitted through the biochamber. A rectangular biochamber was used for measuring the conversion efficiency from light energy to H{sub 2} energy. A quantum meter and radiometer were used to measure the light intensity transmitted through the chamber. Anabaena variabilis was cultured in a BG11 medium with 3.6mM NaNO{sub 3} and the light intensity was 40-50{mu}mol/m{sup 2}/s in the growth phase and 120-140{mu}mol/m{sup 2}/s in the H{sub 2} production phase. The maximum H{sub 2} production was 50ml for 40h and cell density was 1.2g/l. The H{sub 2} production rate was 4.1ml H{sub 2}/g dry cell weight/h. Based on the light absorbed in the H{sub 2} production phase, the energy conversion efficiency from light to H{sub 2} was 1.5% on average and 3.9% at the maximum. Based on the light energy absorbed in the cell growth and H{sub 2} production phases, the energy conversion efficiency was 1.1% on average. (author)

  7. Whole Cell Biosensor Using Anabaena torulosa with Optical Transduction for Environmental Toxicity Evaluation

    Directory of Open Access Journals (Sweden)

    Ling Shing Wong

    2013-01-01

    Full Text Available A whole cell-based biosensor using Anabaena torulosa for the detection of heavy metals (Cu, Pb, and Cd, 2,4-dichlorophenoxyacetate (2,4-D, and chlorpyrifos was constructed. The cyanobacteria were entrapped on a cellulose membrane through filtration. Then, the membrane was dried and fixed into a cylindrical well, which was designed to be attached to an optical probe. The probe was connected to fluorescence spectrometer with optical fibre. The presence of the toxicants was indicated by the change of fluorescence emission, before and after the exposure. The linear detection ranges for Cu, Pb, and Cd were 2.5–10.0 µg/L, 0.5–5.0 µg/L, and 0.5–10.0 µg/L, respectively, while 2,4-D and chlorpyrifos shared similar linear ranges of 0.05–0.75 µg/L. The biosensor showed good sensitivity with the lowest limits of detection (LLD for Cu, Pb, Cd, 2,4-D and chlorpyrifos determined at 1.195 µg/L, 0.100 µg/L, 0.027 µg/L, 0.025 µg/L, and 0.025 µg/L, respectively. The overall reproducibility of the biosensor (n=3 was <±6.35%. The biosensor had been tested with different combinations of toxicants, with the results showing predominantly antagonistic responses. The results confirmed that the biosensor constructed in this report is suitable to be used in quantitative and qualitative detections of heavy metals and pesticides.

  8. Functional characterization of PccH, a key cytochrome for electron transfer from electrodes to the bacterium Geobacter sulfurreducens.

    Science.gov (United States)

    Dantas, Joana M; Tomaz, Diogo M; Morgado, Leonor; Salgueiro, Carlos A

    2013-08-19

    The cytochrome PccH from Geobacter sulfurreducens (Gs) plays a crucial role in current-consuming fumarate-reducing biofilms. Deletion of pccH gene inhibited completely electron transfer from electrodes toward Gs cells. The pccH gene was cloned and the protein heterologously expressed in Escherichia coli. Complementary biophysical techniques including CD, UV-visible and NMR spectroscopy were used to characterize PccH. This cytochrome contains one low-spin c-type heme with His-Met axial coordination and unusual low-reduction potential. This reduction potential is pH-dependent, within the Gs physiological pH range, and is discussed within the context of the electron transfer mechanisms from electrodes to Gs cells.

  9. Comparison of Microcystis aeruginosa (PCC7820 and PCC7806) growth and intracellular microcystins content determined by liquid chromatography-mass spectrometry, enzyme-linked immunosorbent assay anti-Adda and phosphatase bioassay.

    Science.gov (United States)

    Ríos, V; Moreno, I; Prieto, A I; Soria-Díaz, M E; Frías, J E; Cameán, A M

    2014-03-01

    Cyanobacteria are able to produce several metabolites that have toxic effects on humans and animals. Among these cyanotoxins, the hepatotoxic microcystins (MC) occur frequently. The intracellular MC content produced by two strains of Microcystis aeruginosa, PCC7806 and PCC7820, and its production kinetics during the culture time were studied in order to elucidate the conditions that favour the growth and proliferation of these toxic strains. Intracellular MC concentrations measured by liquid chromatography (LC) coupled to electrospray ionization mass spectrometer (MS) were compared with those obtained by enzyme-linked immunosorbent assay (ELISA) anti-Adda and protein phosphatase 2A (PP2A) inhibition assays. It has been demonstrated there are discrepancies in the quantification of MC content when comparing ELISA and LC-MS results. However, a good correlation has been obtained between PP2A inhibition assay and LC-MS. Three MC were identified using LC-MS in the PCC7806 strain: MC-LR, demethylated MC-LR and a new variant detected for the first time in this strain, [L-MeSer(7)] MC-LR. In PCC7820, MC-LR, D-Asp(3)-MCLR, Dglu(OCH3)-MCLR, MC-LY, MC-LW and MC-LF were identificated. The major one was MC-LR in both strains, representing 81 and 79% of total MC, respectively. The total MC content in M. aeruginosa PCC7820 was almost three-fold higher than in PCC7806 extracts.

  10. PHOTOSYNTHETIC, BIOCHEMICAL AND ENZYMATIC INVESTIGATION OF Anabaena fertilissima IN RESPONSE TO AN INSECTICIDE-HEXACHLORO-HEXAHYDRO-METHANOBENZODIOXATHIEPINE- OXIDE

    Directory of Open Access Journals (Sweden)

    Kumar, Nirmal J.I

    2009-09-01

    Full Text Available A study on the heterocystous, nitrogen fixing cyanobacterium, Anabaena fertilissima was carried out to investigate the effect of an organochlorine insecticide (hexachloro-hexahydro-methano-benzodioxathiepineoxide, called as endosulfan at different concentrations of 3, 6 and 12 μgml-1 on the photosynthetic pigments-Chl-a, Carotenoids and Phycobiliproteins-phycocyanin, allophycocyanin and phycoerythrin, stress metabolites such as carbohydrates, proteins, amino acids, phenols and enzyme activities-nitrate reductase and glutamine synthetase. The insecticide- Endosulfan showed to be deleteriously affecting the activities in the cyanobacterium. As early as the 4th day, chl-a and carotenoids reduced by 38% and 20% respectively. The phycobiliproteins declined by 60%, 64% and 28% with respect to Phycocyanin, Allophycocyanin and Phycoerythrin. Moreover, Endosulfan adversely depleted the cellular activities, leading to a marked decrease in the carbohydrates, proteins, phenols and amino acids and enzymes-nitrate reductase and glutamine synthetase. Despite of deleterious effects of Endosulfan on the cyanobacterium Anabaena fertilissima, a unique regenerating ability in presence of the insecticide was observed by the end of 12 days in the lower doses of insecticide.

  11. The LysR-type transcription factor PacR is a global regulator of photosynthetic carbon assimilation in Anabaena.

    Science.gov (United States)

    Picossi, Silvia; Flores, Enrique; Herrero, Antonia

    2015-09-01

    Cyanobacteria perform water-splitting photosynthesis and are important primary producers impacting the carbon and nitrogen cycles at global scale. They fix CO2 through ribulose-bisphosphate carboxylase/oxygenase (RuBisCo) and have evolved a distinct CO2 concentrating mechanism (CCM) that builds high CO2 concentrations in the vicinity of RuBisCo favouring its carboxylase activity. Filamentous cyanobacteria such as Anabaena fix CO2 in photosynthetic vegetative cells, which donate photosynthate to heterocysts that rely on a heterotrophic metabolism to fix N2 . CCM elements are induced in response to inorganic carbon limitation, a cue that exposes the photosynthetic apparatus to photodamage by over-reduction. An Anabaena mutant lacking the LysR-type transcription factor All3953 grew poorly and dies under high light. The rbcL operon encoding RuBisCo was induced upon carbon limitation in the wild type but not in the mutant. ChIP-Seq analysis was used to globally identify All3953 targets under carbon limitation. Targets include, besides rbcL, genes encoding CCM elements, photorespiratory pathway- photosystem- and electron transport-related components, and factors, including flavodiiron proteins, with a demonstrated or putative function in photoprotection. Quantitative reverse transcription polymerase chain reaction analysis of selected All3953 targets showed regulation in the wild type but not in the mutant. All3953 (PacR) is a global regulator of carbon assimilation in an oxygenic photoautotroph.

  12. Generation and Evaluation of a Genome-Scale Metabolic Network Model of Synechococcus elongatus PCC7942

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    Julián Triana

    2014-08-01

    Full Text Available The reconstruction of genome-scale metabolic models and their applications represent a great advantage of systems biology. Through their use as metabolic flux simulation models, production of industrially-interesting metabolites can be predicted. Due to the growing number of studies of metabolic models driven by the increasing genomic sequencing projects, it is important to conceptualize steps of reconstruction and analysis. We have focused our work in the cyanobacterium Synechococcus elongatus PCC7942, for which several analyses and insights are unveiled. A comprehensive approach has been used, which can be of interest to lead the process of manual curation and genome-scale metabolic analysis. The final model, iSyf715 includes 851 reactions and 838 metabolites. A biomass equation, which encompasses elementary building blocks to allow cell growth, is also included. The applicability of the model is finally demonstrated by simulating autotrophic growth conditions of Synechococcus elongatus PCC7942.

  13. Generation and Evaluation of a Genome-Scale Metabolic Network Model of Synechococcus elongatus PCC7942

    Science.gov (United States)

    Triana, Julián; Montagud†, Arnau; Siurana, Maria; Fuente, David; Urchueguía, Arantxa; Gamermann, Daniel; Torres, Javier; Tena, Jose; de Córdoba, Pedro Fernández; Urchueguía, Javier F.

    2014-01-01

    The reconstruction of genome-scale metabolic models and their applications represent a great advantage of systems biology. Through their use as metabolic flux simulation models, production of industrially-interesting metabolites can be predicted. Due to the growing number of studies of metabolic models driven by the increasing genomic sequencing projects, it is important to conceptualize steps of reconstruction and analysis. We have focused our work in the cyanobacterium Synechococcus elongatus PCC7942, for which several analyses and insights are unveiled. A comprehensive approach has been used, which can be of interest to lead the process of manual curation and genome-scale metabolic analysis. The final model, iSyf715 includes 851 reactions and 838 metabolites. A biomass equation, which encompasses elementary building blocks to allow cell growth, is also included. The applicability of the model is finally demonstrated by simulating autotrophic growth conditions of Synechococcus elongatus PCC7942. PMID:25141288

  14. Blueprint for a minimal photoautotrophic cell: conserved and variable genes in Synechococcus elongatus PCC 7942

    Directory of Open Access Journals (Sweden)

    Peretó Juli

    2011-01-01

    Full Text Available Abstract Background Simpler biological systems should be easier to understand and to engineer towards pre-defined goals. One way to achieve biological simplicity is through genome minimization. Here we looked for genomic islands in the fresh water cyanobacteria Synechococcus elongatus PCC 7942 (genome size 2.7 Mb that could be used as targets for deletion. We also looked for conserved genes that might be essential for cell survival. Results By using a combination of methods we identified 170 xenologs, 136 ORFans and 1401 core genes in the genome of S. elongatus PCC 7942. These represent 6.5%, 5.2% and 53.6% of the annotated genes respectively. We considered that genes in genomic islands could be found if they showed a combination of: a unusual G+C content; b unusual phylogenetic similarity; and/or c a small number of the highly iterated palindrome 1 (HIP1 motif plus an unusual codon usage. The origin of the largest genomic island by horizontal gene transfer (HGT could be corroborated by lack of coverage among metagenomic sequences from a fresh water microbialite. Evidence is also presented that xenologous genes tend to cluster in operons. Interestingly, most genes coding for proteins with a diguanylate cyclase domain are predicted to be xenologs, suggesting a role for horizontal gene transfer in the evolution of Synechococcus sensory systems. Conclusions Our estimates of genomic islands in PCC 7942 are larger than those predicted by other published methods like SIGI-HMM. Our results set a guide to non-essential genes in S. elongatus PCC 7942 indicating a path towards the engineering of a model photoautotrophic bacterial cell.

  15. Criminalidade organizada nas prisões e os ataques do PCC Organized criminality in prisons and the attacks of the PCC

    Directory of Open Access Journals (Sweden)

    Sérgio Adorno

    2007-12-01

    Full Text Available A emergência da criminalidade organizada nas prisões brasileiras, em especial no Estado de São Paulo, constitui objeto deste artigo. Tomam-se como ponto de partida e referência para análise as ondas de ataques desencadeadas pelo Primeiro Comando da Capital (PCC, de maio a agosto de 2006, que resultaram em inúmeros mortos, paralisaram cidades e acuaram as autoridades encarregadas de aplicar lei e ordem. A emergência da criminalidade organizada é analisada sob eixos determinados: cenário internacional e contexto brasileiro, antecedentes históricos, enraizamento do crime na sociedade e papel das políticas públicas penitenciárias.The advent of organized crime in Brazilian prisons, especially in the state of São Paulo, constitutes the object of this article. The waves of attack unleashed by the Capital's First Command (PCC - Primeiro Comando da Capital, in May 2006, which resulted in countless deaths, brought cities to a halt, and cornered authorities in charge preventing them from applying law and order are the starting as well as reference points taken. The advent of organized criminality is analyzed under the light of determined axes: the international scenario and the Brazilian context, the historical antecedents, the taking root of crime in society and the role of penitentiary public policies.

  16. Performance evaluation for PCC-OFDM systems impaired by carrier frequency offset over AWGN channels

    Institute of Scientific and Technical Information of China (English)

    ZHOU Peng; ZHAO ChunMing; SHI ZhiHua; GONG XiaoQun

    2008-01-01

    Orthogonal frequency division multiplexing (OFDM) is sensitive to carrier fre- quency offset (CFO), which destroys the orthogonality and causes inter-carrier interference (ICI). ICI self-cancellation schemes based on polynomial cancellation coding (PCC-OFDM) can evidently reduce the sensitivity to CFO. In this paper, we analyze the performance of PCC-OFDM systems impaired by CFO over additive white gaussian noise (AWGN) channels. Two criteria are used to evaluate the effect of CFO on performance degradations. Firstly, the closed-form expressions of the average carrier-to-interference power ratio (CIR) and the statistical average ICI power, both of which reflect the desired power loss, are presented. Simulation and analytical results show that the theoretlcel expressions depend crucially on the normalized frequency offset and are hardly relevant to the number of subcarriers. Secondly, by exploiting the properties of the Beaulieu series, the effect of CFO on symbol error rate (SER) and bit error rate (BER) performance for PCC-OFDM sys- tems are exactly expressed as the sum of an infinite series in terms of the charac- teristic function (CHF) of ICI. We consider the systems modulated with binary phase shift keying (BPSK), quadrature PSK (QPSK), 8-ary PSK (8-PSK), and 16-ary quadrature amplitude modulation (16-QAM), and all above modulation schemes are mapped with Gray codes for the evaluations of BER.

  17. Protein (Cyanobacteria): 329974 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available tein Arthrospira sp. PCC 8005 MSIVHPLPNSEFVLLGYLATVPHLRNIKIGSRFLEYIINVVQQDDKSLILEVEHPDFGENRELKQRRVAFYRRLGAKIFQDIIYIFPALDGTTTTEMMLMIIGEKHHDKLPQTLVQQLIRDLYSEVYNCNPDDSIFNWIADIKHDINLVS ...

  18. Protein (Cyanobacteria): 138867 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available ynechocystis sp. PCC 6803 MFKKLGEVEKIKFKNWCVDKNNLMVKEKWFGKEVKEDRRMVWFGVGIELGKNEKFKGLEIDNSLKKRCLEFYGENFNSLLLIKYGDGSKLNLHKDRDCFDKKVVIVNSGICVFEYDGERKILEDGKIYEIDGKKSHGVVKVVGERYSLSIRKVL ...

  19. Protein (Cyanobacteria): 138866 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available ynechocystis sp. PCC 6803 MFKKLGEVEKIKFKNWCVDKNNLMVKEKWFGKEVKEDRRMVWFGVGIELGKNEKFKGLEIDNSLKKRCLEFYGENFNSLLLIKYGDGSKLNLHKDRDCFDKKVVIVNSGICVFEYDGERKILEDGKIYEIDGKKSHGVVKVVGERYSLSIRKVL ...

  20. Protein (Cyanobacteria): 398381 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available 1699 Synechocystis sp. PCC 6803 MFLTALRSFLLFLAVTCLSLAIAMPAWALTEVPLTEIDYKPCPADLAEGNVGSGSSSPANCFLVTGIANNRTGKTVYDADVFGRIYDANHEPAMQNRTRLGNIAEIPPGKSDFEVRISVPAQQPLPLQLEQFKASGFSAKIRGQAL ...

  1. Protein (Cyanobacteria): 15118 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available aguanine reductase Pseudanabaena sp. PCC 7367 MTVTDQEEKYGERAIAANQLNTFPNPRPGREYKVNITLPEFTCKCPFSGYPDFATIYITYVPDELVVELKAIKLYINGYRDRYISHEESINQILDDFIAACDPIRVQIKGDYNPRGNVHTMVEINYEKPIA ...

  2. Protein (Cyanobacteria): 208270 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available transferase Halothece sp. PCC 7418 MKIVIARDFNDFARCIMIRTQVFVMEQGISAEIETDEWENHSTHYLAGDGEKALATARSRLINNQTAKIERVAVLKEARSQGVGTELMRYILQEIHSYSNIQTIKLGSQNSAIPFYEKLGFQVIGEEYLDAGIPHHLMMQRINT ...

  3. Protein (Cyanobacteria): 444250 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available ynechocystis sp. PCC 6803 MIFEQGIEIKASATVVEQCFTDLDLMHLWLNPALRCEPIGQWSTAIGGRSRFTIQIPLLKPSLKSVVVERSPGLVVWQFKGFFQGQDRWECRPLEEGTYLLNRFEFTVPNPVVQWGFQMFAARWTSADMQAQLRRLKQVAEREYINSGLHS ...

  4. Protein (Cyanobacteria): 120103 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available HDLDPLTTELKKLGLQVHLETSGSHPFSGNFDWVTFSPKPYKKPHDSIYNYVNELKVVVANEEDLHMAEVQAAKLSLTVIKYLQPEWNTPNSKELIFDFVLKHPQWRISLQTHKFLNVR ... ...ece sp. PCC 7424 MLTYFMKTVDLTNCTYPIVETFHSVQGEGAWTGVSAFFIRLGGCDVYCPWCDQKESWNAKRHPHQSVDTLAQAAKMANPAIVIITGGEPLM

  5. Protein (Cyanobacteria): 345021 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available e Calothrix sp. PCC 7507 MAKEIERKFLVNGDSWREIAEGCVYCQGYISTQKTVTVRIRIAGNQGYLTIKGPSVKYSRSEFEYSIPVQDAQEMIDTLCDRPLIEKTRYRIEFGGLTWEIDEFDGVNQGLIIAEVELSDEEQQIELPTWIGEEVSDDPKYFNSNLVKHPFSQW ...

  6. Protein (Cyanobacteria): 426260 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available aining protein Nostoc sp. PCC 7524 MKAAEYLSSAAKSVNEIPGITEATILEYFATLNAGEFLATAALFAEDGVMYPPFESGIVGPDAIANYLQQEAQDIKADTHQGIVEPLDNQHIQVQVTGKAQTSWCSVNVLWIFILNQHKEIIDAKIKLLASPQELLALRRE ...

  7. Protein (Cyanobacteria): 409390 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available protein Oscillatoria sp. PCC 6506 MESLNGFIALIGGILIGLSATLLLAFNGRIAGISGIVNGAIAFSKQEVWRWIFIVGMLLGGVIYEYGLAPQPTPTPALTPWAMTIGGFLVGFGTRMGGGCTSGHGVCGLGRLSMRSLVAVLTFMITAILTVFVVRHVLQLSI ...

  8. Protein (Cyanobacteria): 426188 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available protein Microcoleus sp. PCC 7113 MTIAEDKSTTTPSATGVDWTIEGIDESVVWRYFQTMNAADYEGTAALFAPTGALHPPFEEPIEGKEAIATYLKAEAKGMQLFPREGIAEALEEDQIQIQVKGKVQTSLFGVNVAWIFILNPEREILYAQIKLLASPQELLNLRR ...

  9. Protein (Cyanobacteria): 278725 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available l3776 Nostoc sp. PCC 7120 MSPTSTDCGKDVSMTAETLESHLLILEDDQGRKEFSLDQPLYSIGRDKESNIRLVSQFVSRRHATLVRLPKNNSYYYRIVDGDGKGRASANGLMINGRKLPAHDLKNEDEIVFGPKVRAIYYLLKNTQRSGQTDASEYDITLINPGMTEDVEEL ...

  10. Protein (Cyanobacteria): 136794 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available MAMLLSNPEYLQYRLLEWLEGMVQAHDLLAIEIRLSALLKEQLESLLGGPQYRLLEPFLVQADQTILGQAPAAVAEEEAEMMTLGE ... ...echocystis sp. PCC 6803 MQKDFERLFHRAEDHYLQPPEIISFHKQLGLMRERLSAYRLLRDNEIVIFQAIADRLEEEFSNVPATQLQQALLHWISVLRYGA

  11. Protein (Cyanobacteria): 81404 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available _06604 Lyngbya sp. PCC 8106 MNAEVSLFTIGFTRKSAEQFFGILKKAGVTRLIDARLNNSSQLAGFAKKKDLEYFLKVICNIDYIHLLDLSPTKEILDEYKKNGEDWQVYERQFLQLMRDRQVEEKFSPELFYKGCLLCSEATPERCHRRLVAEYLQEKWTTINLNVYHL ...

  12. Protein (Cyanobacteria): 292628 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available n Arthrospira sp. PCC 8005 MDDSSAIAHISTRHPHQSSLKPCNFLGVRIIPNVPGINMKFERDTIVKLTIGSGCVLGSLAFPPLAAAEGMVWGNILATALGNVAAGNTANAVDALIDAREGRVSLENQDLTKAVGKAILYETLRERRRYHPRSQTTGRQNPRISRKNRRPSQG ...

  13. Protein (Cyanobacteria): 518319094 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available hypothetical protein Calothrix sp. PCC 7103 MKSGYPKNNNAYIELLKGFPPRPITSHEEFVATQKVIDSLIDKKGQLTRDEQDYLNILGTIVYEYEEKQVKIPDIYGIDLLKALLSELNLSTKDLIPIFKTESHVSNVLNGKIDLTVEDISKLANFFKISPAAFVKK

  14. Protein (Cyanobacteria): 43286 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available 1 Synechococcus sp. PCC 7335 MSVRLYFGNLPRSLEREEFEAIFTEDSDNLVSVKLISDRKTGKCRGFGFVTAKDDTTADALVEKYNGFTLQDATLKVEKAMPRTEKETEGSRGENSPQRRQKKSGGKRGGNNVVVAESQTADAGPDPRWAQDLAKLKEMLAAQTTAS ...

  15. Protein (Cyanobacteria): 24292 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available in Oscillatoria sp. PCC 6506 MSKIVLLDAGPLGMISHPRNNPEIKFWLENLLRAGISVKVSEVADYEVRRELLRLNKEKGLQRLDNLIDRLGYTPITREVMLKAAEFWADARKQGQPTANNQALDADVILAAQAFTISNQGENTVIATTNVRHLTRFVPAKIWNEIA ...

  16. Protein (Cyanobacteria): 130181 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available tein Arthrospira sp. PCC 8005 MSFLIDTNILLRSADANHSMYADAVTATNILLAQGGDVCIIPQNLIEFWNVYTRPVDKNGLGHTPTEAAAEVNRLKGLFLLLPDRLAIYSEWERLVLTYGVRGVNVHDARLVAAMLIHGLTHILTFNIRDFARYGEVMAVHPMDVRS ...

  17. Protein (Cyanobacteria): 141435 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available ein Cyanothece sp. PCC 7424 MYQNILVALDNSPTSEEVFHTALMLAKCFNAQLMLLHVLSPEAPDSPINFAPYATSYDIVIVEKYQREWEKFKQDSLDKLKTLAEQANEQGIKTNYAQYYGSPGRLICDQATQSKADLIVMGRRGHSTLNELFLGSVSSYVIHHSHCCIHLVQS ...

  18. Protein (Cyanobacteria): 362664 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available tein Cyanobium sp. PCC 7001 MTTTLSSPARLGTDEPLDPASAFVAVALSAVSWDGVLTMAGSRALRHSLDYRHPYRDYAPDQTVALLDGLMAILRRQGPQHLMVMAAEALNPNQRATAYAVAAEIMRSDGPLEDDERNILSNLAATLELGDAVTIPVHSVMDLLHADLG ...

  19. Protein (Cyanobacteria): 264443 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available Leptolyngbya sp. PCC 7376 MKRLFLSLSVAMVALAIAKPAMAENPDHVARLLETGACQGCNLIGAELSGKHLIGADLRDANLSYANLANANLEGADLTGANLAGADMTEAFLTNAVLNNARLDRVDFTAAKMYDTLVVDASMEDLTLTDAELYNTAISVGGSYEQFVPEGE ...

  20. Protein (Cyanobacteria): 136652 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available in Arthrospira sp. PCC 8005 MGFLMKRLSDFMKSLRLDHLVTVLMAVTLLLVTAACSNTETASYNNSQADQYQEDVAENLSDFRQELEDLAAEVQTKVEEAAGVVKEEGGDMTKEAKRQLEDAADVVKQEGGDMTKEAKRQLEDATDVVKEKVGEAKKSAQRTIEDVSDAADS ...

  1. Protein (Cyanobacteria): 78536 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available 4516 Lyngbya sp. PCC 8106 MSFTQPSQPQPHSSLISFSDGWFILPRRVFPHHTDYAGIVWHGTYMTWMEELRVEGLHWLGVNYSDLVAMGCDLPVVELKVRYHLSVKMGMTILIKGQPLPIKGVRMVWDYQIVSEDHQQLYVSGQVTLVPLSRETGKIMRRLPPLLQDAIAQIQG ...

  2. Protein (Cyanobacteria): 448175 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available ining protein Cyanothece sp. PCC 7424 MKKAQLVLTFFFSFLLAVFVSFNLVVDSAMAFSGPVSESCIDLELSGSILSANCETANGYYEKASINLDEVIGNLDGMLSWDSQNFSQTCEDISLEKRYSITFPILMATCQEAIGGENYMATEVYLDDHIFNVNGTLFYN ...

  3. Protein (Cyanobacteria): 446930 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available ece sp. PCC 7424 MPELEILTNCRFYLELKLKDSKEPIDGIFMDCKGFKCTQEVIEICEVTPNKWGKENKPGQLVRTKLPGNIKTNNLVLKRGMTASKTLWKWFEDVQAGNWAKERRDGSLTIYDQSGTVQARFEFQRAWPSNYTITDVSASSNDVEIEELELACEAFKRIQ ...

  4. The influence of acetyl phosphate on DspA signalling in the Cyanobacterium Synechocystis sp. PCC6803

    Directory of Open Access Journals (Sweden)

    Mullineaux Conrad W

    2005-08-01

    Full Text Available Abstract Background The dspA (hik33 gene, coding for a putative sensory histidine kinase, is conserved in plastids (ycf26 and cyanobacteria. It has been linked with a number of different stress responses in cyanobacteria. Results We constructed an insertional mutant of dspA (ycf26 in Synechocystis 6803. We found little phenotypic effect during nitrogen starvation. However, when the mutation was combined with deletion of the pta gene coding for phosphotransacetylase, a more significant phenotype was observed. Under nitrogen starvation, the pta/dspA double mutant degrades its phycobilisomes less than the wild type and still has about half of its chlorophyll-protein complexes. Conclusion Our data indicates that acetyl-phosphate-dependent phosphorylation of response regulator(s overlaps with DspA-dependent signalling of the degradation of chlorophyll-protein complexes (and to a lesser extent phycobilisomes in Synechocystis 6803.

  5. Dynamic changes in gene expression of the cyanobacterium Synechocystis sp. PCC 6803 in response to nitrogen starvation

    NARCIS (Netherlands)

    Krasikov, V.

    2012-01-01

    In this thesis we exploit the fast moving field of microarray analysis, from its early rise till a first valuable product. A newly developed microarray platform for Synechocystis permits whole-genome transcriptomics of cyanobacteria exposed to environmental stress. This brings new insights into the

  6. Chirality Matters: Synthesis and Consumption of the d-Enantiomer of Lactic Acid by Synechocystis sp. Strain PCC6803

    NARCIS (Netherlands)

    S.A. Angermayr; A.D. van der Woude; D. Correddu; R. Kern; M. Hagemann; K.J. Hellingwerf

    2015-01-01

    Both enantiomers of lactic acid, l-lactic acid and d-lactic acid, can be produced in a sustainable way by a photosynthetic microbial cell factory and thus from CO2, sunlight, and water. Several properties of polylactic acid (a polyester of polymerized lactic acid) depend on the controlled blend of t

  7. Spatial fluctuations in expression of the heterocyst differentiation regulatory gene hetR in Anabaena filaments.

    Science.gov (United States)

    Corrales-Guerrero, Laura; Tal, Asaf; Arbel-Goren, Rinat; Mariscal, Vicente; Flores, Enrique; Herrero, Antonia; Stavans, Joel

    2015-04-01

    Under nitrogen deprivation, filaments of the cyanobacterium Anabaena undergo a process of development, resulting in a one-dimensional pattern of nitrogen-fixing heterocysts separated by about ten photosynthetic vegetative cells. Many aspects of gene expression before nitrogen deprivation and during the developmental process remain to be elucidated. Furthermore, the coupling of gene expression fluctuations between cells along a multicellular filament is unknown. We studied the statistics of fluctuations of gene expression of HetR, a transcription factor essential for heterocyst differentiation, both under steady-state growth in nitrogen-rich conditions and at different times following nitrogen deprivation, using a chromosomally-encoded translational hetR-gfp fusion. Statistical analysis of fluorescence at the individual cell level in wild-type and mutant filaments demonstrates that expression fluctuations of hetR in nearby cells are coupled, with a characteristic spatial range of circa two to three cells, setting the scale for cellular interactions along a filament. Correlations between cells predominantly arise from intercellular molecular transfer and less from cell division. Fluctuations after nitrogen step-down can build up on those under nitrogen-replete conditions. We found that under nitrogen-rich conditions, basal, steady-state expression of the HetR inhibitor PatS, cell-cell communication influenced by the septal protein SepJ and positive HetR auto-regulation are essential determinants of fluctuations in hetR expression and its distribution along filaments. A comparison between the expression of hetR-gfp under nitrogen-rich and nitrogen-poor conditions highlights the differences between the two HetR inhibitors PatS and HetN, as well as the differences in specificity between the septal proteins SepJ and FraC/FraD. Activation, inhibition and cell-cell communication lie at the heart of developmental processes. Our results show that proteins involved in these

  8. Spatial fluctuations in expression of the heterocyst differentiation regulatory gene hetR in Anabaena filaments.

    Directory of Open Access Journals (Sweden)

    Laura Corrales-Guerrero

    2015-04-01

    Full Text Available Under nitrogen deprivation, filaments of the cyanobacterium Anabaena undergo a process of development, resulting in a one-dimensional pattern of nitrogen-fixing heterocysts separated by about ten photosynthetic vegetative cells. Many aspects of gene expression before nitrogen deprivation and during the developmental process remain to be elucidated. Furthermore, the coupling of gene expression fluctuations between cells along a multicellular filament is unknown. We studied the statistics of fluctuations of gene expression of HetR, a transcription factor essential for heterocyst differentiation, both under steady-state growth in nitrogen-rich conditions and at different times following nitrogen deprivation, using a chromosomally-encoded translational hetR-gfp fusion. Statistical analysis of fluorescence at the individual cell level in wild-type and mutant filaments demonstrates that expression fluctuations of hetR in nearby cells are coupled, with a characteristic spatial range of circa two to three cells, setting the scale for cellular interactions along a filament. Correlations between cells predominantly arise from intercellular molecular transfer and less from cell division. Fluctuations after nitrogen step-down can build up on those under nitrogen-replete conditions. We found that under nitrogen-rich conditions, basal, steady-state expression of the HetR inhibitor PatS, cell-cell communication influenced by the septal protein SepJ and positive HetR auto-regulation are essential determinants of fluctuations in hetR expression and its distribution along filaments. A comparison between the expression of hetR-gfp under nitrogen-rich and nitrogen-poor conditions highlights the differences between the two HetR inhibitors PatS and HetN, as well as the differences in specificity between the septal proteins SepJ and FraC/FraD. Activation, inhibition and cell-cell communication lie at the heart of developmental processes. Our results show that proteins

  9. Cyanobacteria contain a structural homologue of the Hfq protein with altered RNA-binding properties

    DEFF Research Database (Denmark)

    Bøggild, Andreas; Overgaard, Martin; Valentin-Hansen, Poul

    2009-01-01

    regulating mRNA turnover in eukaryotes. However, bacterial Hfq proteins are homohexameric, whereas eukaryotic Sm/Lsm proteins are heteroheptameric. Recently, Hfq proteins with poor sequence conservation were identified in archaea and cyanobacteria. In this article, we describe crystal structures of the Hfq...... proteins from the cyanobacteria Synechocystis sp. PCC 6803 and Anabaena PCC 7120 at 1.3 and 2.3 A resolution, respectively, and show that they retain the classic Sm fold despite low sequence conservation. In addition, the intersubunit contacts and RNA-binding site are divergent, and we show biochemically...

  10. Cyanobacteria contain a structural homologue of the Hfq protein with altered RNA binding properties

    DEFF Research Database (Denmark)

    Bøggild, Andreas; Overgaard, Martin; Valentin-Hansen, Poul

    2009-01-01

    regulating mRNA turnover in eukaryotes. However, bacterial Hfq proteins are homohexameric, whereas eukaryotic Sm/Lsm proteins are heteroheptameric. Recently, Hfq proteins with poor sequence conservation were identified in archaea and cyanobacteria. In this article, we describe crystal structures of the Hfq...... proteins from the cyanobacteria Synechocystis sp. PCC 6803 and Anabaena PCC 7120 at 1.3 and 2.3 A resolution, respectively, and show that they retain the classic Sm fold despite low sequence conservation. In addition, the intersubunit contacts and RNA-binding site are divergent, and we show biochemically...

  11. H2 production by Anabaena variabilis mutant in computer controlled two-stage air-lift tubular photobioreactor

    Science.gov (United States)

    Liu, Jian-Guo; Hall, D. O.; Rao, K. K.; Tsygankov, A. A.; Sveshnikov, D. A.

    2000-06-01

    A 4.34 liter two-stage air-lift photobioreactor incorporating Anabaena variabilis ATCC29413 mutant PK84 was used to study H2 production. Results showed that H2 production increased with increasing light intensity from 47 μE/(m2·s) up to 190 μE/(m2·s), but that further increase of light intensity decreased the H2 production because of the inhibition due to the high pO2. The data also indicated that longer argon gas charge resulted in more H2 produced due to the increase of nitrogenase activities and heterocyst frequency, and that more than 1.3 L net H2 was produced from this computer controlled photobioreactor.

  12. Steady state emission of the fluorescent intermediate of Anabaena Sensory Rhodopsin as a function of light adaptation conditions

    Science.gov (United States)

    Cheminal, A.; Léonard, J.; Kim, S. Y.; Jung, K.-H.; Kandori, H.; Haacke, S.

    2013-11-01

    Steady-state fluorescence measurements of the first excited state of the anabaena sensory rhodopsin (ASR), and Bacteriorhodopsin are reported for different light stabilization conditions, including the dark-adapted state. We determine the fluorescence spectra of both all-trans (AT), and 13-cis (13C) protonated Schiff base of retinal, and compare the effect of the proteins. Referenced against the fluorescence quantum yield of AT-bR (2.5 × 10-4) we find for AT-ASR, 13C-ASR, and 13C-bR the values of 3.3 × 10-4, 0.8 × 10-4, and 1.7 × 10-4, respectively. Using reported excited state lifetimes, the radiative rates are deduced, and their differences discussed on the basis of a configuration-dependent oscillator strength.

  13. Direct measurement of excitation transfer dynamics between two trimers in C-phycocyanin hexamer from cyanobacterium Anabaena variabilis

    Science.gov (United States)

    Zhang, Jingmin; Zhao, Fuli; Zheng, Xiguang; Wang, Hezhou

    1999-05-01

    We provide the first experimental evidence for the excitation transfers between two trimers of an isolated C-phycocyanin hexamer (αβ) 6PCL RC27, at the end of the rod proximal to the core of PBS in cyanobacterium of Anabaena variabilis, with picosecond time-resolved fluorescence spectroscopy. Our results strongly suggest that the observed fluorescence decay constants around 20 and 10 ps time scales, shown in anisotropy decay, not in isotropic decay experiments arose from the excitation transfers between two trimers via two types of transfer pathways such as 1β 155↔6β 155 (2β 155↔5β 155 and 3β 155↔4β 155) and 2α 84↔5α 84 (3α 84↔6α 84 and 1α 84↔4α 84) channels and these could be described by Föster dipole-dipole resonance mechanism.

  14. H2 PRODUCTION BY ANABAENA VARIABILIS MUTANT IN COMPUTER CONTROLLED TWO-STAGE AIR-LIFT TUBULAR PHOTOBIOREACTOR

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A 4.34 liter two-stage air-lift photobioreactor incorporating Anabaena variabilis ATCC29413 mutant PK84 was used to study H2 production. Results showed that H2 production increased with increasing light intensity from 47 μE/(m2·s) up to 190 μE/(m2·s), but that further increase of light intensity decreased the H2 production because of the inhibition due to the high pO2. The data also indicated that longer argon gas charge resulted in more H2 produced due to the increase of nitrogenase activities and heterocyst frequency, and that more than 1.3 L net H2 was produced from this computer controlled photobioreactor.

  15. Proteomic strategy for the analysis of the polychlorobiphenyl-degrading cyanobacterium Anabaena PD-1 exposed to Aroclor 1254.

    Directory of Open Access Journals (Sweden)

    Hangjun Zhang

    Full Text Available The cyanobacterium Anabaena PD-1, which was originally isolated from polychlorobiphenyl (PCB-contaminated paddy soils, has capabilities for dechlorinatin and for degrading the commercial PCB mixture Aroclor 1254. In this study, 25 upregulated proteins were identified using 2D electrophoresis (2-DE coupled with matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS. These proteins were involved in (i PCB degradation (i.e., 3-chlorobenzoate-3,4-dioxygenase; (ii transport processes [e.g., ATP-binding cassette (ABC transporter substrate-binding protein, amino acid ABC transporter substrate-binding protein, peptide ABC transporter substrate-binding protein, putrescine-binding protein, periplasmic solute-binding protein, branched-chain amino acid uptake periplasmic solute-binding protein, periplasmic phosphate-binding protein, phosphonate ABC transporter substrate-binding protein, and xylose ABC transporter substrate-binding protein]; (iii energetic metabolism (e.g., methanol/ethanol family pyrroloquinoline quinone (PQQ-dependent dehydrogenase, malate-CoA ligase subunit beta, enolase, ATP synthase β subunit, FOF1 ATP synthase subunit beta, ATP synthase α subunit, and IMP cyclohydrolase; (iv electron transport (cytochrome b6f complex Fe-S protein; (v general stress response (e.g., molecular chaperone DnaK, elongation factor G, and translation elongation factor thermostable; (vi carbon metabolism (methanol dehydrogenase and malate-CoA ligase subunit beta; and (vii nitrogen reductase (nitrous oxide reductase. The results of real-time polymerase chain reaction showed that the genes encoding for dioxygenase, ABC transporters, transmembrane proteins, electron transporter, and energetic metabolism proteins were significantly upregulated during PCB degradation. These genes upregulated by 1.26- to 8.98-fold. These findings reveal the resistance and adaptation of cyanobacterium to the presence of PCBs, shedding light on the

  16. Proteomic strategy for the analysis of the polychlorobiphenyl-degrading cyanobacterium Anabaena PD-1 exposed to Aroclor 1254.

    Science.gov (United States)

    Zhang, Hangjun; Jiang, Xiaojun; Xiao, Wenfeng; Lu, Liping

    2014-01-01

    The cyanobacterium Anabaena PD-1, which was originally isolated from polychlorobiphenyl (PCB)-contaminated paddy soils, has capabilities for dechlorinatin and for degrading the commercial PCB mixture Aroclor 1254. In this study, 25 upregulated proteins were identified using 2D electrophoresis (2-DE) coupled with matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). These proteins were involved in (i) PCB degradation (i.e., 3-chlorobenzoate-3,4-dioxygenase); (ii) transport processes [e.g., ATP-binding cassette (ABC) transporter substrate-binding protein, amino acid ABC transporter substrate-binding protein, peptide ABC transporter substrate-binding protein, putrescine-binding protein, periplasmic solute-binding protein, branched-chain amino acid uptake periplasmic solute-binding protein, periplasmic phosphate-binding protein, phosphonate ABC transporter substrate-binding protein, and xylose ABC transporter substrate-binding protein]; (iii) energetic metabolism (e.g., methanol/ethanol family pyrroloquinoline quinone (PQQ)-dependent dehydrogenase, malate-CoA ligase subunit beta, enolase, ATP synthase β subunit, FOF1 ATP synthase subunit beta, ATP synthase α subunit, and IMP cyclohydrolase); (iv) electron transport (cytochrome b6f complex Fe-S protein); (v) general stress response (e.g., molecular chaperone DnaK, elongation factor G, and translation elongation factor thermostable); (vi) carbon metabolism (methanol dehydrogenase and malate-CoA ligase subunit beta); and (vii) nitrogen reductase (nitrous oxide reductase). The results of real-time polymerase chain reaction showed that the genes encoding for dioxygenase, ABC transporters, transmembrane proteins, electron transporter, and energetic metabolism proteins were significantly upregulated during PCB degradation. These genes upregulated by 1.26- to 8.98-fold. These findings reveal the resistance and adaptation of cyanobacterium to the presence of PCBs, shedding light on the

  17. Induction and differential expression of certain novel proteins in Anabaena L31 under UV-B radiation stress

    Directory of Open Access Journals (Sweden)

    Piyoosh Kumar Babele

    2015-02-01

    Full Text Available For examining how UV-B radiation alters the proteome of the N2-fixing cyanobacterium, Anabaena L31, we extracted proteins from cultures irradiated with UV-B + white light and controls (white light irradiated and analyzed the proteins using two-dimensional gel electrophoresis (2-DE and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS. Twenty one proteins, including 2 hypothetical proteins were identified and placed in 8 functional categories. However several of the proteins were housekeeping proteins involved in key metabolic processes such as carbon, amino acid biosynthesis and energy metabolism, certain p