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Sample records for rrna secondary structures

  1. Two distinct 18S rRNA secondary structures in Dipodascus (Hemiascomycetes).

    Science.gov (United States)

    Ueda-Nishimura, K; Mikata, K

    2000-05-01

    The nucleotide sequences of the 18S rRNA gene from ascomycetous yeast-like fungi in the genera Dipodascus, Galactomyces and Geotrichum were determined and the tested strains were separated into two groups by sequence length. In group 1, the length and secondary structure of 18S rRNA corresponded to those of typical eukaryotes. In group 2, the 18S rRNA gene sequences were about 150 nt shorter than those of most other eukaryotes and the predicted secondary structure lacked helices 10 and E21-5. Many substitutions and some deletions in group 2 18S rRNA gene were not only found in variable regions, but also in regions that are highly conserved among ascomycetes. Despite the considerable differences in 18S rRNA gene sequence and secondary structure between group 2 and other fungi, including group 1, phylogenetic analysis revealed that groups 1 and 2 are closely related. These findings suggest that a number of deletions occurred in the 18S rRNA of the common ancestor of group 2 strains.

  2. Comparative analysis of mt LSU rRNA secondary structures of Odonates: structural variability and phylogenetic signal.

    Science.gov (United States)

    Misof, B; Fleck, G

    2003-12-01

    Secondary structures of the most conserved part of the mt 16S rRNA gene, domains IV and V, have been recently analysed in a comparative study. However, full secondary structures of the mt LSU rRNA molecule are published for only a few insect species. The present study presents full secondary structures of domains I, II, IV and V of Odonates and one representative of mayflies, Ephemera sp. The reconstructions are based on a comparative approach and minimal consensus structures derived from sequence alignments. The inferred structures exhibit remarkable similarities to the published Drosophila melanogaster model, which increases confidence in these structures. Structural variance within Odonates is homoplastic, and neighbour-joining trees based on tree edit distances do not correspond to any of the phylogenetically expected patterns. However, despite homoplastic quantitative structural variation, many similarities between Odonates and Ephemera sp. suggest promising character sets for higher order insect systematics that merit further investigations.

  3. [Characterization of 5S rRNA gene sequence and secondary structure in gymnosperms].

    Science.gov (United States)

    Liu, Zhan-Lin; Zhang, Da-Ming; Wang, Xiao-Ru

    2003-01-01

    In higher plants the primary and the secondary structures of 5S ribosomal RNA gene are considered highly conservative. Little is known about the 5S rRNA gene structure, organization and variation in gyimnosperms. In this study we analyzed sequence and structure variation of 5S rRNA gene in Pinus through cloning and sequencing multiple copies of 5S rDNA repeats from individual trees of five pines, P. bungeana, P. tabulaeformis, P. yunnanensis, P. massoniana and P. densata. Pinus bungeana is from the subgenus Strobus while the other four are from the subgenus Pinus (diploxylon pines). Our results revealed variations in both primary and secondary structure among copies of 5S rDNA within individual genomes and between species. 5S rRNA gene in Pinus is 120 bp long in most of the 122 clones we sequenced except for one or two deletions in three clones. Among these clones 50 unique sequences were identified and they were shared by different pine species. Our sequences were compared to 13 sequences each representing a different gymnosperm species, and to six sequences representing both angiosperm monocots and dicots. Average sequence similarity was 97.1% among Pinus species and 94.3% between Pinus and other gymnosperms. Between gymnosperms and angiosperms the sequence similarity decreased to 88.1%. Similar to other molecular data, significant sequence divergence was found between the two Pinus subgenera. The 5S gene tree (neighbor-joining tree) grouped the four diploxylon pines together and separated them distinctly from P. bungeana. Comparison of sequence divergence within individuals and between species suggested that concerted evolution has been very weak especially after the divergence of the four diploxylon pines. The phylogenetic information contained in the 5S rRNA gene is limited due to its shorter length and the difficulties in identifying orthologous and paralogous copies of rDNA multigene family further complicate its phylogenetic application. Pinus densata is a

  4. The secondary structure of large-subunit rRNA divergent domains, a marker for protist evolution

    DEFF Research Database (Denmark)

    Lenaers, G; Nielsen, Henrik; Engberg, J

    1988-01-01

    The secondary structure of the large-subunit ribosomal RNA (24-26S rRNA) has been studied with emphasis on comparative analysis of the folding patterns of the divergent domains in the available protist sequences, that is Prorocentrum micans (dinoflagellate), Saccharomyces carlsbergensis (yeast), ...

  5. Comparison of primary and secondary 26S rRNA structures in two Tetrahymena species: evidence for a strong evolutionary and structural constraint in expansion segments

    DEFF Research Database (Denmark)

    Engberg, J; Nielsen, Henrik; Lenaers, G

    1990-01-01

    We have determined the nucleotide sequence of the 26S large subunit (LSU) rRNA genes for two Tetrahymena species, T. thermophila and T. pyriformis. The inferred rRNA sequences are presented in their most probable secondary structures based on compensatory mutations, energy, and conservation...

  6. The secondary structure of large-subunit rRNA divergent domains, a marker for protist evolution

    DEFF Research Database (Denmark)

    Lenaers, G; Nielsen, Henrik; Engberg, J

    1988-01-01

    The secondary structure of the large-subunit ribosomal RNA (24-26S rRNA) has been studied with emphasis on comparative analysis of the folding patterns of the divergent domains in the available protist sequences, that is Prorocentrum micans (dinoflagellate), Saccharomyces carlsbergensis (yeast...... on the parsimony method. Both phylogenies suggest three major branchings, the first leading to the dinoflagellate (which branches off first), ciliate and yeast, the second to the slime moulds, and the last to the parasitic flagellates....

  7. Comparison of primary and secondary 26S rRNA structures in two Tetrahymena species: evidence for a strong evolutionary and structural constraint in expansion segments

    DEFF Research Database (Denmark)

    Engberg, J; Nielsen, Henrik; Lenaers, G

    1990-01-01

    . These are regions within the common core of secondary structure where expansions have taken place during the evolution of the rRNA of higher eukaryotes. The dispensable nature of some of the expansion segments has been taken as evidence of their non-functionality. However, our data show that a considerable......We have determined the nucleotide sequence of the 26S large subunit (LSU) rRNA genes for two Tetrahymena species, T. thermophila and T. pyriformis. The inferred rRNA sequences are presented in their most probable secondary structures based on compensatory mutations, energy, and conservation...... selective constraint has operated to preserve the secondary structure of these segments. Especially in the case of the D2 and D8 segments, the presence of a considerable number of compensatory base changes suggests that the secondary structure of these regions is of functional importance. Alternatively...

  8. An updated 18S rRNA phylogeny of tunicates based on mixture and secondary structure models

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    Shenkar Noa

    2009-08-01

    Full Text Available Abstract Background Tunicates have been recently revealed to be the closest living relatives of vertebrates. Yet, with more than 2500 described species, details of their evolutionary history are still obscure. From a molecular point of view, tunicate phylogenetic relationships have been mostly studied based on analyses of 18S rRNA sequences, which indicate several major clades at odds with the traditional class-level arrangements. Nonetheless, substantial uncertainty remains about the phylogenetic relationships and taxonomic status of key groups such as the Aplousobranchia, Appendicularia, and Thaliacea. Results Thirty new complete 18S rRNA sequences were acquired from previously unsampled tunicate species, with special focus on groups presenting high evolutionary rate. The updated 18S rRNA dataset has been aligned with respect to the constraint on homology imposed by the rRNA secondary structure. A probabilistic framework of phylogenetic reconstruction was adopted to accommodate the particular evolutionary dynamics of this ribosomal marker. Detailed Bayesian analyses were conducted under the non-parametric CAT mixture model accounting for site-specific heterogeneity of the evolutionary process, and under RNA-specific doublet models accommodating the occurrence of compensatory substitutions in stem regions. Our results support the division of tunicates into three major clades: 1 Phlebobranchia + Thaliacea + Aplousobranchia, 2 Appendicularia, and 3 Stolidobranchia, but the position of Appendicularia could not be firmly resolved. Our study additionally reveals that most Aplousobranchia evolve at extremely high rates involving changes in secondary structure of their 18S rRNA, with the exception of the family Clavelinidae, which appears to be slowly evolving. This extreme rate heterogeneity precluded resolving with certainty the exact phylogenetic placement of Aplousobranchia. Finally, the best fitting secondary-structure and CAT-mixture models

  9. Molecular evolution of rDNA in early diverging Metazoa: First comparative analysis and phylogenetic application of complete SSU rRNA secondary structures in Porifera

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    Wörheide Gert

    2008-02-01

    Full Text Available Abstract Background The cytoplasmic ribosomal small subunit (SSU, 18S ribosomal RNA (rRNA is the most frequently-used gene for molecular phylogenetic studies. However, information regarding its secondary structure is neglected in most phylogenetic analyses. Incorporation of this information is essential in order to apply specific rRNA evolutionary models to overcome the problem of co-evolution of paired sites, which violates the basic assumption of the independent evolution of sites made by most phylogenetic methods. Information about secondary structure also supports the process of aligning rRNA sequences across taxa. Both aspects have been shown to increase the accuracy of phylogenetic reconstructions within various taxa. Here, we explore SSU rRNA secondary structures from the three extant classes of Phylum Porifera (Grant, 1836, a pivotal, but largely unresolved taxon of early branching Metazoa. This is the first phylogenetic study of poriferan SSU rRNA data to date that includes detailed comparative secondary structure information for all three sponge classes. Results We found base compositional and structural differences in SSU rRNA among Demospongiae, Hexactinellida (glass sponges and Calcarea (calcareous sponges. We showed that analyses of primary rRNA sequences, including secondary structure-specific evolutionary models, in combination with reconstruction of the evolution of unusual structural features, reveal a substantial amount of additional information. Of special note was the finding that the gene tree topologies of marine haplosclerid demosponges, which are inconsistent with the current morphology-based classification, are supported by our reconstructed evolution of secondary structure features. Therefore, these features can provide alternative support for sequence-based topologies and give insights into the evolution of the molecule itself. To encourage and facilitate the application of rRNA models in phylogenetics of early

  10. Mitochondrial rRNA secondary structures and genome arrangements distinguish chelicerates: comparisons with a harvestman (Arachnida: Opiliones: Phalangium opilio).

    Science.gov (United States)

    Masta, Susan E

    2010-01-01

    Arachnids are a highly diverse group of arthropods, and many of the mitochondrial genomes that have been sequenced from arachnids possess unusual features in their inferred gene structures and genome organization. The first complete sequence of a mitochondrial genome from the arachnid order Opiliones (harvestmen) is presented here. Secondary structures of the two mitochondrial ribosomal subunits of Phalangium opilio are inferred and compared to mitochondrial rRNA structures of a hexapod and a chelicerate. The large subunit rRNA of P. opilio is found to have more helices conserved than in other arthropods, while the small subunit rRNA shows a complexity similar to that of other arthropods. These comparisons suggest that a reduction in rRNA complexity occurred in Pancrustacea after the divergence of Pancrustacea and Chelicerata from a common ancestor. The gene arrangement of the mitochondrial genome of P. opilio is compared with the gene order of taxa from all seven other orders of arachnids for which representative mitochondrial genomes have been sequenced. Taxa from five of these seven orders possess gene arrangements identical to that of Limulus polyphemus, and P. opilio is found to have a similar arrangement. However, in P. opilio, some genes near the putative control region are rearranged, with the suite of genes encoding tRNA(Gln), the control region, and tRNA(Ile) located downstream of the two ribosomal RNA genes, and upstream of where they are typically located in chelicerates. The genome encodes only 21 of the typical 22 mitochondrial tRNA genes and lacks the gene for tRNA(Leu(CUN)). The protein-coding genes in the mitochondrial genome of P. opilio show a significantly decreased use of codons recognized by tRNA(Leu(CUN)), likely due to selection to utilize the more specific tRNA(Leu(UUR)) anticodon. The gene arrangement and lack of a tRNA(Leu(CUN)) gene in P. opilio is most parsimoniously explained by the occurrence of at least two translocation events, one

  11. Model-Free RNA Sequence and Structure Alignment Informed by SHAPE Probing Reveals a Conserved Alternate Secondary Structure for 16S rRNA.

    Science.gov (United States)

    Lavender, Christopher A; Lorenz, Ronny; Zhang, Ge; Tamayo, Rita; Hofacker, Ivo L; Weeks, Kevin M

    2015-05-01

    Discovery and characterization of functional RNA structures remains challenging due to deficiencies in de novo secondary structure modeling. Here we describe a dynamic programming approach for model-free sequence comparison that incorporates high-throughput chemical probing data. Based on SHAPE probing data alone, ribosomal RNAs (rRNAs) from three diverse organisms--the eubacteria E. coli and C. difficile and the archeon H. volcanii--could be aligned with accuracies comparable to alignments based on actual sequence identity. When both base sequence identity and chemical probing reactivities were considered together, accuracies improved further. Derived sequence alignments and chemical probing data from protein-free RNAs were then used as pseudo-free energy constraints to model consensus secondary structures for the 16S and 23S rRNAs. There are critical differences between these experimentally-informed models and currently accepted models, including in the functionally important neck and decoding regions of the 16S rRNA. We infer that the 16S rRNA has evolved to undergo large-scale changes in base pairing as part of ribosome function. As high-quality RNA probing data become widely available, structurally-informed sequence alignment will become broadly useful for de novo motif and function discovery.

  12. Model-Free RNA Sequence and Structure Alignment Informed by SHAPE Probing Reveals a Conserved Alternate Secondary Structure for 16S rRNA.

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    Christopher A Lavender

    2015-05-01

    Full Text Available Discovery and characterization of functional RNA structures remains challenging due to deficiencies in de novo secondary structure modeling. Here we describe a dynamic programming approach for model-free sequence comparison that incorporates high-throughput chemical probing data. Based on SHAPE probing data alone, ribosomal RNAs (rRNAs from three diverse organisms--the eubacteria E. coli and C. difficile and the archeon H. volcanii--could be aligned with accuracies comparable to alignments based on actual sequence identity. When both base sequence identity and chemical probing reactivities were considered together, accuracies improved further. Derived sequence alignments and chemical probing data from protein-free RNAs were then used as pseudo-free energy constraints to model consensus secondary structures for the 16S and 23S rRNAs. There are critical differences between these experimentally-informed models and currently accepted models, including in the functionally important neck and decoding regions of the 16S rRNA. We infer that the 16S rRNA has evolved to undergo large-scale changes in base pairing as part of ribosome function. As high-quality RNA probing data become widely available, structurally-informed sequence alignment will become broadly useful for de novo motif and function discovery.

  13. What an rRNA secondary structure tells about phylogeny of fungi in Ascomycota with emphasis on evolution of major types of ascus.

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    Wen-Ying Zhuang

    Full Text Available BACKGROUND: RNA secondary structure is highly conserved throughout evolution. The higher order structure is fundamental in establishing important structure-function relationships. Nucleotide sequences from ribosomal RNA (rRNA genes have made a great contribution to our understanding of Ascomycota phylogeny. However, filling the gaps between molecular phylogeny and morphological assumptions based on ascus dehiscence modes and type of fruitbodies at the higher level classification of the phylum remains an unfulfilled task faced by mycologists. METHODOLOGY/PRINCIPAL FINDINGS: We selected some major groups of Ascomycota to view their phylogenetic relationships based on analyses of rRNA secondary structure. Using rRNA secondary structural information, here, we converted nucleotide sequences into the structure ones over a 20-symbol code. Our structural analyses together with ancestral character state reconstruction produced reasonable phylogenetic position for the class Geoglossomycetes as opposed to the classic nucleotide analyses. Judging from the secondary structure analyses with consideration of mode of ascus dehiscence and the ability of forming fruitbodies, we draw a clear picture of a possible evolutionary route for fungal asci and some major groups of fungi in Ascomycota. The secondary structure trees show a more reasonable phylogenetic position for the class Geoglossomycetes. CONCLUSIONS: Our results illustrate that asci lacking of any dehiscence mechanism represent the most primitive type. Passing through the operculate and Orbilia-type asci, bitunicate asci occurred. The evolution came to the most advanced inoperculate type. The ascus-producing fungi might be derived from groups lacking of the capacity to form fruitbodies, and then evolved multiple times. The apothecial type of fruitbodies represents the ancestral state, and the ostiolar type is advanced. The class Geoglossomycetes is closely related to Leotiomycetes and Sordariomycetes

  14. Insight into higher-level phylogeny of Neuropterida: Evidence from secondary structures of mitochondrial rRNA genes and mitogenomic data.

    Science.gov (United States)

    Song, Nan; Lin, Aili; Zhao, Xincheng

    2018-01-01

    It is well known that the rRNA structure information is important to assist phylogenetic analysis through identifying homologous positions to improve alignment accuracy. In addition, the secondary structure of some conserved motifs is highly stable among distantly related taxa, which can provide potentially informative characters for estimating phylogeny. In this paper, we applied the high-throughput pooled sequencing approach to the determination of neuropteran mitogenomes. Four complete mitogenome sequences were obtained: Micromus angulatus (Hemerobiidae), Chrysoperla nipponensis (Chrysopidae), Rapisma sp. (Ithonidae), and Thaumatosmylus sp. (Osmylidae). This allowed us to sample more complete mitochondrial RNA gene sequences. Secondary structure diagrams for the complete mitochondrial small and large ribosomal subunit RNA genes of eleven neuropterid species were predicted. Comparative analysis of the secondary structures indicated a closer relationship of Megaloptera and Neuroptera. This result was congruent with the resulting phylogeny inferred from sequence alignments of all 37 mitochondrial genes, namely the hypothesis of (Raphidioptera + (Megaloptera + Neuroptera)).

  15. Structural similarity of E. coli 5S rRNA in solution and within the ribosome.

    Science.gov (United States)

    Skibinska, Lidia; Banachowicz, Ewa; Gapiński, Jacek; Patkowski, Adam; Barciszewski, Jan

    2004-02-15

    The article presents translational and rotational diffusion coefficients of 5S rRNA determined experimentally by the method of dynamic light scattering (DLS) and its comparison with the values predicted for different models of this molecule. The tertiary structure of free 5S rRNA was proposed on the basis of the atomic structures of the 5S rRNA from E. coli and H. marismortui extracted from the ribosome. A comparison of the values of DT, tauR, and Rg predicted for different models with experimental results for the free molecule in solution suggests that free 5S rRNA is less compact than that in the complex with ribosomal proteins. In general, the molecules of 5S rRNA consist of three domains: a short one and two longer ones. As follows from a comparison of the results of our simulations with experimental values, in the molecule in solution the two closest helical fragments of the longer domains remain collinear, whereas the short domain takes a position significantly deviated from them. Copyright 2004 Wiley Periodicals, Inc.

  16. Conserved secondary structures in Aspergillus.

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    Abigail Manson McGuire

    2008-07-01

    Full Text Available Recent evidence suggests that the number and variety of functional RNAs (ncRNAs as well as cis-acting RNA elements within mRNAs is much higher than previously thought; thus, the ability to computationally predict and analyze RNAs has taken on new importance. We have computationally studied the secondary structures in an alignment of six Aspergillus genomes. Little is known about the RNAs present in this set of fungi, and this diverse set of genomes has an optimal level of sequence conservation for observing the correlated evolution of base-pairs seen in RNAs.We report the results of a whole-genome search for evolutionarily conserved secondary structures, as well as the results of clustering these predicted secondary structures by structural similarity. We find a total of 7450 predicted secondary structures, including a new predicted approximately 60 bp long hairpin motif found primarily inside introns. We find no evidence for microRNAs. Different types of genomic regions are over-represented in different classes of predicted secondary structures. Exons contain the longest motifs (primarily long, branched hairpins, 5' UTRs primarily contain groupings of short hairpins located near the start codon, and 3' UTRs contain very little secondary structure compared to other regions. There is a large concentration of short hairpins just inside the boundaries of exons. The density of predicted intronic RNAs increases with the length of introns, and the density of predicted secondary structures within mRNA coding regions increases with the number of introns in a gene.There are many conserved, high-confidence RNAs of unknown function in these Aspergillus genomes, as well as interesting spatial distributions of predicted secondary structures. This study increases our knowledge of secondary structure in these aspergillus organisms.

  17. Domain V of 23S rRNA contains all the structural elements necessary for recognition by the ErmE methyltransferase

    DEFF Research Database (Denmark)

    Vester, B; Douthwaite, S

    1994-01-01

    to erythromycin and clindamycin. The degree of resistance corresponds to the level of ermE expression. In turn, ermE expression also correlates with the proportion of 23S rRNA molecules that are dimethylated at adenine 2058. The methyltransferase was isolated in an active, concentrated form from E. coli...... disrupted by removal of magnesium ions. We conclude that the main features that are specifically recognized by the ErmE methyltransferase are displayed within the primary and secondary structures of 23S rRNA domain V....

  18. Nearly complete rRNA genes from 371 Animalia: updated structure-based alignment and detailed phylogenetic analysis.

    Science.gov (United States)

    Mallatt, Jon; Craig, Catherine Waggoner; Yoder, Matthew J

    2012-09-01

    This study presents a manually constructed alignment of nearly complete rRNA genes from most animal clades (371 taxa from ~33 of the ~36 metazoan phyla), expanded from the 197 sequences in a previous study. This thorough, taxon-rich alignment, available at http://www.wsu.edu/~jmallatt/research/rRNAalignment.html and in the Dryad Repository (doi: http://dx.doi.org/10.5061/dryad.1v62kr3q), is based rigidly on the secondary structure of the SSU and LSU rRNA molecules, and is annotated in detail, including labeling of the erroneous sequences (contaminants). The alignment can be used for future studies of the molecular evolution of rRNA. Here, we use it to explore if the larger number of sequences produces an improved phylogenetic tree of animal relationships. Disappointingly, the resolution did not improve, neither when the standard maximum-likelihood method was used, nor with more sophisticated methods that partitioned the rRNA into paired and unpaired sites (stem, loop, bulge, junction), or accounted for the evolution of the paired sites. For example, no doublet model of paired-site substitutions (16-state, 16A and 16B, 7A-F, or 6A-C models) corrected the placement of any rogue taxa or increased resolution. The following findings are from the simplest, standard, ML analysis. The 371-taxon tree only imperfectly supported the bilaterian clades of Lophotrochozoa and Ecdysozoa, and this problem remained after 17 taxa with unstably positioned sequences were omitted from the analysis. The problem seems to stem from base-compositional heterogeneity across taxa and from an overrepresentation of highly divergent sequences among the newly added taxa (e.g., sequences from Cephalopoda, Rotifera, Acoela, and Myxozoa). The rogue taxa continue to concentrate in two locations in the rRNA tree: near the base of Arthropoda and of Bilateria. The approximately uncertain (AU) test refuted the monophyly of Mollusca and of Chordata, probably due to long-branch attraction of the highly

  19. Assembly of proteins and 5 S rRNA to transcripts of the major structural domains of 23 S rRNA

    DEFF Research Database (Denmark)

    Ostergaard, P; Phan, H; Johansen, L B

    1998-01-01

    The six major structural domains of 23 S rRNA from Escherichia coli, and all combinations thereof, were synthesized as separate T7 transcripts and reconstituted with total 50 S subunit proteins. Analysis by one and two-dimensional gel electrophoresis demonstrated the presence of at least one......+VI. This indicates that there are two major protein assembly centres located at the ends of the 23 S rRNA, which is consistent with an earlier view that in vitro protein assembly nucleates around proteins L24 and L3. Although similar protein assembly patterns were observed over a range of temperature and magnesium...... approach was used to map the putative binding regions on domain V of protein L9 and the 5 S RNA-L5-L18 complex....

  20. Secondary structure and domain architecture of the 23S and 5S rRNAs

    Science.gov (United States)

    Petrov, Anton S.; Bernier, Chad R.; Hershkovits, Eli; Xue, Yuzhen; Waterbury, Chris C.; Hsiao, Chiaolong; Stepanov, Victor G.; Gaucher, Eric A.; Grover, Martha A.; Harvey, Stephen C.; Hud, Nicholas V.; Wartell, Roger M.; Fox, George E.; Williams, Loren Dean

    2013-01-01

    We present a de novo re-determination of the secondary (2°) structure and domain architecture of the 23S and 5S rRNAs, using 3D structures, determined by X-ray diffraction, as input. In the traditional 2° structure, the center of the 23S rRNA is an extended single strand, which in 3D is seen to be compact and double helical. Accurately assigning nucleotides to helices compels a revision of the 23S rRNAstructure. Unlike the traditional 2° structure, the revised 2° structure of the 23S rRNA shows architectural similarity with the 16S rRNA. The revised 2° structure also reveals a clear relationship with the 3D structure and is generalizable to rRNAs of other species from all three domains of life. The 2° structure revision required us to reconsider the domain architecture. We partitioned the 23S rRNA into domains through analysis of molecular interactions, calculations of 2D folding propensities and compactness. The best domain model for the 23S rRNA contains seven domains, not six as previously ascribed. Domain 0 forms the core of the 23S rRNA, to which the other six domains are rooted. Editable 2° structures mapped with various data are provided (http://apollo.chemistry.gatech.edu/RibosomeGallery). PMID:23771137

  1. Secondary structure and domain architecture of the 23S and 5S rRNAs.

    Science.gov (United States)

    Petrov, Anton S; Bernier, Chad R; Hershkovits, Eli; Xue, Yuzhen; Waterbury, Chris C; Hsiao, Chiaolong; Stepanov, Victor G; Gaucher, Eric A; Grover, Martha A; Harvey, Stephen C; Hud, Nicholas V; Wartell, Roger M; Fox, George E; Williams, Loren Dean

    2013-08-01

    We present a de novo re-determination of the secondary (2°) structure and domain architecture of the 23S and 5S rRNAs, using 3D structures, determined by X-ray diffraction, as input. In the traditional 2° structure, the center of the 23S rRNA is an extended single strand, which in 3D is seen to be compact and double helical. Accurately assigning nucleotides to helices compels a revision of the 23S rRNAstructure. Unlike the traditional 2° structure, the revised 2° structure of the 23S rRNA shows architectural similarity with the 16S rRNA. The revised 2° structure also reveals a clear relationship with the 3D structure and is generalizable to rRNAs of other species from all three domains of life. The 2° structure revision required us to reconsider the domain architecture. We partitioned the 23S rRNA into domains through analysis of molecular interactions, calculations of 2D folding propensities and compactness. The best domain model for the 23S rRNA contains seven domains, not six as previously ascribed. Domain 0 forms the core of the 23S rRNA, to which the other six domains are rooted. Editable 2° structures mapped with various data are provided (http://apollo.chemistry.gatech.edu/RibosomeGallery).

  2. Molecular phylogenetics and systematics of the bivalve family Ostreidae based on rRNA sequence-structure models and multilocus species tree.

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    Daniele Salvi

    Full Text Available The bivalve family Ostreidae has a worldwide distribution and includes species of high economic importance. Phylogenetics and systematic of oysters based on morphology have proved difficult because of their high phenotypic plasticity. In this study we explore the phylogenetic information of the DNA sequence and secondary structure of the nuclear, fast-evolving, ITS2 rRNA and the mitochondrial 16S rRNA genes from the Ostreidae and we implemented a multi-locus framework based on four loci for oyster phylogenetics and systematics. Sequence-structure rRNA models aid sequence alignment and improved accuracy and nodal support of phylogenetic trees. In agreement with previous molecular studies, our phylogenetic results indicate that none of the currently recognized subfamilies, Crassostreinae, Ostreinae, and Lophinae, is monophyletic. Single gene trees based on Maximum likelihood (ML and Bayesian (BA methods and on sequence-structure ML were congruent with multilocus trees based on a concatenated (ML and BA and coalescent based (BA approaches and consistently supported three main clades: (i Crassostrea, (ii Saccostrea, and (iii an Ostreinae-Lophinae lineage. Therefore, the subfamily Crassostreinae (including Crassostrea, Saccostreinae subfam. nov. (including Saccostrea and tentatively Striostrea and Ostreinae (including Ostreinae and Lophinae taxa are recognized [corrected]. Based on phylogenetic and biogeographical evidence the Asian species of Crassostrea from the Pacific Ocean are assigned to Magallana gen. nov., whereas an integrative taxonomic revision is required for the genera Ostrea and Dendostrea. This study pointed out the suitability of the ITS2 marker for DNA barcoding of oyster and the relevance of using sequence-structure rRNA models and features of the ITS2 folding in molecular phylogenetics and taxonomy. The multilocus approach allowed inferring a robust phylogeny of Ostreidae providing a broad molecular perspective on their systematics.

  3. Molecular phylogenetics and systematics of the bivalve family Ostreidae based on rRNA sequence-structure models and multilocus species tree.

    Science.gov (United States)

    Salvi, Daniele; Macali, Armando; Mariottini, Paolo

    2014-01-01

    The bivalve family Ostreidae has a worldwide distribution and includes species of high economic importance. Phylogenetics and systematic of oysters based on morphology have proved difficult because of their high phenotypic plasticity. In this study we explore the phylogenetic information of the DNA sequence and secondary structure of the nuclear, fast-evolving, ITS2 rRNA and the mitochondrial 16S rRNA genes from the Ostreidae and we implemented a multi-locus framework based on four loci for oyster phylogenetics and systematics. Sequence-structure rRNA models aid sequence alignment and improved accuracy and nodal support of phylogenetic trees. In agreement with previous molecular studies, our phylogenetic results indicate that none of the currently recognized subfamilies, Crassostreinae, Ostreinae, and Lophinae, is monophyletic. Single gene trees based on Maximum likelihood (ML) and Bayesian (BA) methods and on sequence-structure ML were congruent with multilocus trees based on a concatenated (ML and BA) and coalescent based (BA) approaches and consistently supported three main clades: (i) Crassostrea, (ii) Saccostrea, and (iii) an Ostreinae-Lophinae lineage. Therefore, the subfamily Crassostreinae (including Crassostrea), Saccostreinae subfam. nov. (including Saccostrea and tentatively Striostrea) and Ostreinae (including Ostreinae and Lophinae taxa) are recognized [corrected]. Based on phylogenetic and biogeographical evidence the Asian species of Crassostrea from the Pacific Ocean are assigned to Magallana gen. nov., whereas an integrative taxonomic revision is required for the genera Ostrea and Dendostrea. This study pointed out the suitability of the ITS2 marker for DNA barcoding of oyster and the relevance of using sequence-structure rRNA models and features of the ITS2 folding in molecular phylogenetics and taxonomy. The multilocus approach allowed inferring a robust phylogeny of Ostreidae providing a broad molecular perspective on their systematics.

  4. Combinatorics of saturated secondary structures of RNA.

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    Clote, P

    2006-11-01

    Following Zuker (1986), a saturated secondary structure for a given RNA sequence is a secondary structure such that no base pair can be added without violating the definition of secondary structure, e.g., without introducing a pseudoknot. In the Nussinov-Jacobson energy model (Nussinov and Jacobson, 1980), where the energy of a secondary structure is -1 times the number of base pairs, saturated secondary structures are local minima in the energy landscape, hence form kinetic traps during the folding process. Here we present recurrence relations and closed form asymptotic limits for combinatorial problems related to the number of saturated secondary structures. In addition, Python source code to compute the number of saturated secondary structures having k base pairs can be found at the web servers link of bioinformatics.bc.edu/clotelab/.

  5. Community structure, cellular rRNA content, and activity of sulfate-reducing bacteria in marine Arctic sediments

    DEFF Research Database (Denmark)

    Ravenschlag, K.; Sahm, K.; Knoblauch, C.

    2000-01-01

    The community structure of sulfate-reducing bacteria (SRB) of a marine Arctic sediment (Smeerenburg-fjorden, Svalbard) a-as characterized by both fluorescence in situ hybridization (FISH) and rRNA slot blot hybridization by using group- and genus-specific 16S rRNA-targeted oligonucleotide probes...

  6. Secondary structure of synthetic oligopeptides

    CERN Document Server

    Martinez-Insua, M

    2000-01-01

    The secondary structure of three hydrophobic peptides P2, PRMo and P4 was studied by a combination of Circular Dichroism (CD), Fourier Transform InfraRed (FTIR) and Photoinduced Electron Transfer (PET). These peptides were fluorescence labelled in the central part of the backbone and contained two modified glutamic acid residues (relative positions i, i+4): one conjugated with the fluorescence methoxynapththalene electron donor (DON) and the other with the piperidone electron acceptor (ACC). The three peptides were synthesised to study the length dependence of the switch between alpha-helix and the 3 sub 1 sub 0 -helix conformations, previously observed for peptide PRM1 (Hungerford et al., Angew. Chem., Int. Ed. Engl., 1996, 35, 326-329). The CD and FTIR data indicated that peptides P2, PRMo and P4 adopt alpha-helical conformation in organic media in the temperature range studied and no conformational switch was detected. Furthermore, a mathematical correlation was observed in the PET data, questioning the ag...

  7. Similarity of bacterial community structure between Asian dust and its sources determined by rRNA gene-targeted approaches.

    Science.gov (United States)

    Nishimura, Yoshinori; Kenzaka, Takehiko; Sueyoshi, Akio; Li, Pinfang; Fujiyama, Hideyasu; Baba, Takashi; Yamaguchi, Nobuyasu; Nasu, Masao

    2010-01-01

    The atmospheric movement of arid soil can play an important role in the movement of microorganisms attached to soil microparticles. Bacterial community structures in Asian dust collected at Beijing were investigated using the 16S rRNA gene sequence and compared to those in arid soil, a possible source of the dust. Asian dust samples contained 2.5×10(7) to 3.5×10(9) copies of the 16S rRNA gene gram(-1). Therefore, more than 10(13) bacterial cells (km)(-2) per month were estimated to arrive in Beijing via Asian dust. Terminal restriction fragment length polymorphism analysis revealed that the bacterial community structures in Asian dust samples differed greatly according to the scale of the dust event. The bacterial communities from major dust events were similar to those from an arid region of China.

  8. Combinatorics of locally optimal RNA secondary structures.

    Science.gov (United States)

    Fusy, Eric; Clote, Peter

    2014-01-01

    It is a classical result of Stein and Waterman that the asymptotic number of RNA secondary structures is 1.104366∙n-3/2∙2.618034n. Motivated by the kinetics of RNA secondary structure formation, we are interested in determining the asymptotic number of secondary structures that are locally optimal, with respect to a particular energy model. In the Nussinov energy model, where each base pair contributes -1 towards the energy of the structure, locally optimal structures are exactly the saturated structures, for which we have previously shown that asymptotically, there are 1.07427∙n-3/2∙2.35467n many saturated structures for a sequence of length n. In this paper, we consider the base stacking energy model, a mild variant of the Nussinov model, where each stacked base pair contributes -1 toward the energy of the structure. Locally optimal structures with respect to the base stacking energy model are exactly those secondary structures, whose stems cannot be extended. Such structures were first considered by Evers and Giegerich, who described a dynamic programming algorithm to enumerate all locally optimal structures. In this paper, we apply methods from enumerative combinatorics to compute the asymptotic number of such structures. Additionally, we consider analogous combinatorial problems for secondary structures with annotated single-stranded, stacking nucleotides (dangles).

  9. Bayesian segmentation of protein secondary structure.

    Science.gov (United States)

    Schmidler, S C; Liu, J S; Brutlag, D L

    2000-01-01

    We present a novel method for predicting the secondary structure of a protein from its amino acid sequence. Most existing methods predict each position in turn based on a local window of residues, sliding this window along the length of the sequence. In contrast, we develop a probabilistic model of protein sequence/structure relationships in terms of structural segments, and formulate secondary structure prediction as a general Bayesian inference problem. A distinctive feature of our approach is the ability to develop explicit probabilistic models for alpha-helices, beta-strands, and other classes of secondary structure, incorporating experimentally and empirically observed aspects of protein structure such as helical capping signals, side chain correlations, and segment length distributions. Our model is Markovian in the segments, permitting efficient exact calculation of the posterior probability distribution over all possible segmentations of the sequence using dynamic programming. The optimal segmentation is computed and compared to a predictor based on marginal posterior modes, and the latter is shown to provide significant improvement in predictive accuracy. The marginalization procedure provides exact secondary structure probabilities at each sequence position, which are shown to be reliable estimates of prediction uncertainty. We apply this model to a database of 452 nonhomologous structures, achieving accuracies as high as the best currently available methods. We conclude by discussing an extension of this framework to model nonlocal interactions in protein structures, providing a possible direction for future improvements in secondary structure prediction accuracy.

  10. Predicting Protein Secondary Structure with Markov Models

    DEFF Research Database (Denmark)

    Fischer, Paul; Larsen, Simon; Thomsen, Claus

    2004-01-01

    we are considering here, is to predict the secondary structure from the primary one. To this end we train a Markov model on training data and then use it to classify parts of unknown protein sequences as sheets, helices or coils. We show how to exploit the directional information contained......The primary structure of a protein is the sequence of its amino acids. The secondary structure describes structural properties of the molecule such as which parts of it form sheets, helices or coils. Spacial and other properties are described by the higher order structures. The classification task...

  11. Structure of ERA in complex with the 3′ end of 16S rRNA: Implications for ribosome biogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Chao; Zhou, Xiaomei; Tropea, Joseph E.; Austin, Brian P.; Waugh, David S.; Court, Donald L.; Ji, Xinhua; (NCI)

    2009-10-09

    ERA, composed of an N-terminal GTPase domain followed by an RNA-binding KH domain, is essential for bacterial cell viability. It binds to 16S rRNA and the 30S ribosomal subunit. However, its RNA-binding site, the functional relationship between the two domains, and its role in ribosome biogenesis remain unclear. We have determined two crystal structures of ERA, a binary complex with GDP and a ternary complex with a GTP-analog and the {sub 1531}AUCACCUCCUUA{sub 1542} sequence at the 3' end of 16S rRNA. In the ternary complex, the first nine of the 12 nucleotides are recognized by the protein. We show that GTP binding is a prerequisite for RNA recognition by ERA and that RNA recognition stimulates its GTP-hydrolyzing activity. Based on these and other data, we propose a functional cycle of ERA, suggesting that the protein serves as a chaperone for processing and maturation of 16S rRNA and a checkpoint for assembly of the 30S ribosomal subunit. The AUCA sequence is highly conserved among bacteria, archaea, and eukaryotes, whereas the CCUCC, known as the anti-Shine-Dalgarno sequence, is conserved in noneukaryotes only. Therefore, these data suggest a common mechanism for a highly conserved ERA function in all three kingdoms of life by recognizing the AUCA, with a 'twist' for noneukaryotic ERA proteins by also recognizing the CCUCC.

  12. Crystal Structure of the Thermus thermophilus 16 S rRNA Methyltransferase RsmC in Complex with Cofactor and Substrate Guanosine

    Energy Technology Data Exchange (ETDEWEB)

    Demirci, H.; Gregory, S; Dahlberg, A; Jogl, G

    2008-01-01

    Post-transcriptional modification is a ubiquitous feature of ribosomal RNA in all kingdoms of life. Modified nucleotides are generally clustered in functionally important regions of the ribosome, but the functional contribution to protein synthesis is not well understood. Here we describe high resolution crystal structures for the N{sup 2}-guanine methyltransferase RsmC that modifies residue G1207 in 16 S rRNA near the decoding site of the 30 S ribosomal subunit. RsmC is a class I S-adenosyl-l-methionine-dependent methyltransferase composed of two methyltransferase domains. However, only one S-adenosyl-l-methionine molecule and one substrate molecule, guanosine, bind in the ternary complex. The N-terminal domain does not bind any cofactor. Two structures with bound S-adenosyl-l-methionine and S-adenosyl-l-homocysteine confirm that the cofactor binding mode is highly similar to other class I methyltransferases. Secondary structure elements of the N-terminal domain contribute to cofactor-binding interactions and restrict access to the cofactor-binding site. The orientation of guanosine in the active site reveals that G1207 has to disengage from its Watson-Crick base pairing interaction with C1051 in the 16 S rRNA and flip out into the active site prior to its modification. Inspection of the 30 S crystal structure indicates that access to G1207 by RsmC is incompatible with the native subunit structure, consistent with previous suggestions that this enzyme recognizes a subunit assembly intermediate.

  13. Secondary structure and rigidity in model proteins.

    Science.gov (United States)

    Perticaroli, Stefania; Nickels, Jonathan D; Ehlers, Georg; O'Neill, Hugh; Zhang, Qui; Sokolov, Alexei P

    2013-10-28

    There is tremendous interest in understanding the role that secondary structure plays in the rigidity and dynamics of proteins. In this work we analyze nanomechanical properties of proteins chosen to represent different secondary structures: α-helices (myoglobin and bovine serum albumin), β-barrels (green fluorescent protein), and α + β + loop structures (lysozyme). Our experimental results show that in these model proteins, the β motif is a stiffer structural unit than the α-helix in both dry and hydrated states. This difference appears not only in the rigidity of the protein, but also in the amplitude of fast picosecond fluctuations. Moreover, we show that for these examples the secondary structure correlates with the temperature- and hydration-induced changes in the protein dynamics and rigidity. Analysis also suggests a connection between the length of the secondary structure (α-helices) and the low-frequency vibrational mode, the so-called boson peak. The presented results suggest an intimate connection of dynamics and rigidity with the protein secondary structure.

  14. RNA Secondary Structure Analysis Using RNAstructure.

    Science.gov (United States)

    Mathews, David H

    2014-06-17

    RNAstructure is a user-friendly program for the prediction and analysis of RNA secondary structure. It is available as a Web server, as a program with a graphical user interface, or as a set of command-line tools. The programs are available for Microsoft Windows, Macintosh OS X, or Linux. This unit provides protocols for RNA secondary structure prediction (using the Web server or the graphical user interface) and prediction of high-affinity oligonucleotide biding sites to a structured RNA target (using the graphical user interface). Copyright © 2014 John Wiley & Sons, Inc.

  15. Enumerating secondary structures and structural moieties for circular RNAs

    CERN Document Server

    Cuesta, José A

    2016-01-01

    A quantitative characterization of the relationship between molecular sequence and structure is essential to improve our understanding of how function emerges. This particular genotype-phenotype map has been often studied in the context of RNA sequences, with the folded configurations standing as a proxy for the phenotype. Here, we count the secondary structures of circular RNAs of length $n$ and calculate the asymptotic distributions of different structural moieties, such as stems or hairpin loops, by means of symbolic combinatorics. Circular RNAs differ in essential ways from their linear counterparts. From the mathematical viewpoint, the enumeration of the corresponding secondary structures demands the use of combinatorial techniques additional to those used for linear RNAs. The asymptotic number of secondary structures for circular RNAs grows as $a^nn^{-5/2}$, with a depending on particular constraints applied to the secondary structure. The abundance of any structural moiety is normally distributed in th...

  16. Secondary structures of rRNAs from all three domains of life.

    Directory of Open Access Journals (Sweden)

    Anton S Petrov

    Full Text Available Accurate secondary structures are important for understanding ribosomes, which are extremely large and highly complex. Using 3D structures of ribosomes as input, we have revised and corrected traditional secondary (2° structures of rRNAs. We identify helices by specific geometric and molecular interaction criteria, not by co-variation. The structural approach allows us to incorporate non-canonical base pairs on parity with Watson-Crick base pairs. The resulting rRNAstructures are up-to-date and consistent with three-dimensional structures, and are information-rich. These 2° structures are relatively simple to understand and are amenable to reproduction and modification by end-users. The 2° structures made available here broadly sample the phylogenetic tree and are mapped with a variety of data related to molecular interactions and geometry, phylogeny and evolution. We have generated 2° structures for both large subunit (LSU 23S/28S and small subunit (SSU 16S/18S rRNAs of Escherichia coli, Thermus thermophilus, Haloarcula marismortui (LSU rRNA only, Saccharomyces cerevisiae, Drosophila melanogaster, and Homo sapiens. We provide high-resolution editable versions of the 2° structures in several file formats. For the SSU rRNA, the 2° structures use an intuitive representation of the central pseudoknot where base triples are presented as pairs of base pairs. Both LSU and SSU secondary maps are available (http://apollo.chemistry.gatech.edu/RibosomeGallery. Mapping of data onto 2° structures was performed on the RiboVision server (http://apollo.chemistry.gatech.edu/RiboVision.

  17. Structural and functional insights into the molecular mechanism of rRNA m6A methyltransferase RlmJ.

    Science.gov (United States)

    Punekar, Avinash S; Liljeruhm, Josefine; Shepherd, Tyson R; Forster, Anthony C; Selmer, Maria

    2013-11-01

    RlmJ catalyzes the m(6)A2030 methylation of 23S rRNA during ribosome biogenesis in Escherichia coli. Here, we present crystal structures of RlmJ in apo form, in complex with the cofactor S-adenosyl-methionine and in complex with S-adenosyl-homocysteine plus the substrate analogue adenosine monophosphate (AMP). RlmJ displays a variant of the Rossmann-like methyltransferase (MTase) fold with an inserted helical subdomain. Binding of cofactor and substrate induces a large shift of the N-terminal motif X tail to make it cover the cofactor binding site and trigger active-site changes in motifs IV and VIII. Adenosine monophosphate binds in a partly accommodated state with the target N6 atom 7 Å away from the sulphur of AdoHcy. The active site of RlmJ with motif IV sequence 164DPPY167 is more similar to DNA m(6)A MTases than to RNA m(6)2A MTases, and structural comparison suggests that RlmJ binds its substrate base similarly to DNA MTases T4Dam and M.TaqI. RlmJ methylates in vitro transcribed 23S rRNA, as well as a minimal substrate corresponding to helix 72, demonstrating independence of previous modifications and tertiary interactions in the RNA substrate. RlmJ displays specificity for adenosine, and mutagenesis experiments demonstrate the critical roles of residues Y4, H6, K18 and D164 in methyl transfer.

  18. Continuum secondary structure captures protein flexibility

    DEFF Research Database (Denmark)

    Anderson, C.A.F.; Palmer, A.G.; Brunak, Søren

    2002-01-01

    with different hydrogen bond thresholds. The final continuous assignment for a single NMR model successfully reflected the structural variations observed between all NMR models in the ensemble. The structural variations between NMR models were verified to correlate with thermal motion; these variations were...... captured by the continuous assignments. Because the continuous assignment reproduces the structural variation between many NMR models from one single model, functionally important variation can be extracted from a single X-ray structure. Thus, continuous assignments of secondary structure may affect future...

  19. RNAmute: RNA secondary structure mutation analysis tool

    Directory of Open Access Journals (Sweden)

    Barash Danny

    2006-04-01

    Full Text Available Abstract Background RNAMute is an interactive Java application that calculates the secondary structure of all single point mutations, given an RNA sequence, and organizes them into categories according to their similarity with respect to the wild type predicted structure. The secondary structure predictions are performed using the Vienna RNA package. Several alternatives are used for the categorization of single point mutations: Vienna's RNAdistance based on dot-bracket representation, as well as tree edit distance and second eigenvalue of the Laplacian matrix based on Shapiro's coarse grain tree graph representation. Results Selecting a category in each one of the processed tables lists all single point mutations belonging to that category. Selecting a mutation displays a graphical drawing of the single point mutation and the wild type, and includes basic information such as associated energies, representations and distances. RNAMute can be used successfully with very little previous experience and without choosing any parameter value alongside the initial RNA sequence. The package runs under LINUX operating system. Conclusion RNAMute is a user friendly tool that can be used to predict single point mutations leading to conformational rearrangements in the secondary structure of RNAs. In several cases of substantial interest, notably in virology, a point mutation may lead to a loss of important functionality such as the RNA virus replication and translation initiation because of a conformational rearrangement in the secondary structure.

  20. Secondary structure of fluorescence labelled synthetic peptides

    CERN Document Server

    Martin, A S

    2000-01-01

    A series of eight synthetic oligopeptides has been prepared and their secondary structures investigated using various techniques. The project represents a continuation of an investigation into thermally induced changes in secondary structure. Following the previously reported results, the change in structure was initially thought to represent a change from an alpha-helix at low temperature to 3 sub 1 sub 0 -helix at high temperature. However, the results reported herein suggest the peptides retain an alpha-helical configuration at all temperatures studied, but that this helix can adopt at least two related forms. The difference in the structures relates to the nature of the H-bonds which may or may not involve an additional interaction from water molecules or side-chains. The peptides were encouraged to adopt a helical configuration by the inclusion of alpha- aminoisobutyric acid (Aib) residues. Also, modified forms of glutamic acid were included in the sequences. These had pendant donor (4-methoxy naphthalen...

  1. General combinatorics of RNA secondary structure.

    Science.gov (United States)

    Liao, Bo; Wang, Tian-ming

    2004-09-01

    The total number of RNA secondary structures of a given length with minimal hairpin loop length m(m>0) and with minimal stack length l(l>0) is computed, under the assumption that all base pairs can occur. Asymptotics are derived from the determination of recurrence relations of decomposition properties.

  2. PEGylated nanoparticles: protein corona and secondary structure

    Science.gov (United States)

    Runa, Sabiha; Hill, Alexandra; Cochran, Victoria L.; Payne, Christine K.

    2014-09-01

    Nanoparticles have important biological and biomedical applications ranging from drug and gene delivery to biosensing. In the presence of extracellular proteins, a "corona" of proteins adsorbs on the surface of the nanoparticles, altering their interaction with cells, including immune cells. Nanoparticles are often functionalized with polyethylene glycol (PEG) to reduce this non-specific adsorption of proteins. To understand the change in protein corona that occurs following PEGylation, we first quantified the adsorption of blood serum proteins on bare and PEGylated gold nanoparticles using gel electrophoresis. We find a threefold decrease in the amount of protein adsorbed on PEGylated gold nanoparticles compared to the bare gold nanoparticles, showing that PEG reduces, but does not prevent, corona formation. To determine if the secondary structure of corona proteins was altered upon adsorption onto the bare and PEGylated gold nanoparticles, we use CD spectroscopy to characterize the secondary structure of bovine serum albumin following incubation with the nanoparticles. Our results show no significant change in protein secondary structure following incubation with bare or PEGylated nanoparticles. Further examination of the secondary structure of bovine serum albumin, α2-macroglobulin, and transferrin in the presence of free PEG showed similar results. These findings provide important insights for the use of PEGylated gold nanoparticles under physiological conditions.

  3. Nested PCR Biases in Interpreting Microbial Community Structure in 16S rRNA Gene Sequence Datasets.

    Directory of Open Access Journals (Sweden)

    Guoqin Yu

    Full Text Available Sequencing of the PCR-amplified 16S rRNA gene has become a common approach to microbial community investigations in the fields of human health and environmental sciences. This approach, however, is difficult when the amount of DNA is too low to be amplified by standard PCR. Nested PCR can be employed as it can amplify samples with DNA concentration several-fold lower than standard PCR. However, potential biases with nested PCRs that could affect measurement of community structure have received little attention.In this study, we used 17 DNAs extracted from vaginal swabs and 12 DNAs extracted from stool samples to study the influence of nested PCR amplification of the 16S rRNA gene on the estimation of microbial community structure using Illumina MiSeq sequencing. Nested and standard PCR methods were compared on alpha- and beta-diversity metrics and relative abundances of bacterial genera. The effects of number of cycles in the first round of PCR (10 vs. 20 and microbial diversity (relatively low in vagina vs. high in stool were also investigated. Vaginal swab samples showed no significant difference in alpha diversity or community structure between nested PCR and standard PCR (one round of 40 cycles. Stool samples showed significant differences in alpha diversity (except Shannon's index and relative abundance of 13 genera between nested PCR with 20 cycles in the first round and standard PCR (P27% of total OTUs in stool.Nested PCR introduced bias in estimated diversity and community structure. The bias was more significant for communities with relatively higher diversity and when more cycles were applied in the first round of PCR. We conclude that nested PCR could be used when standard PCR does not work. However, rare taxa detected by nested PCR should be validated by other technologies.

  4. Evaluation of the suitability of free-energy minimization using nearest-neighbor energy parameters for RNA secondary structure prediction

    Directory of Open Access Journals (Sweden)

    Cobaugh Christian W

    2004-08-01

    Full Text Available Abstract Background A detailed understanding of an RNA's correct secondary and tertiary structure is crucial to understanding its function and mechanism in the cell. Free energy minimization with energy parameters based on the nearest-neighbor model and comparative analysis are the primary methods for predicting an RNA's secondary structure from its sequence. Version 3.1 of Mfold has been available since 1999. This version contains an expanded sequence dependence of energy parameters and the ability to incorporate coaxial stacking into free energy calculations. We test Mfold 3.1 by performing the largest and most phylogenetically diverse comparison of rRNA and tRNA structures predicted by comparative analysis and Mfold, and we use the results of our tests on 16S and 23S rRNA sequences to assess the improvement between Mfold 2.3 and Mfold 3.1. Results The average prediction accuracy for a 16S or 23S rRNA sequence with Mfold 3.1 is 41%, while the prediction accuracies for the majority of 16S and 23S rRNA structures tested are between 20% and 60%, with some having less than 20% prediction accuracy. The average prediction accuracy was 71% for 5S rRNA and 69% for tRNA. The majority of the 5S rRNA and tRNA sequences have prediction accuracies greater than 60%. The prediction accuracy of 16S rRNA base-pairs decreases exponentially as the number of nucleotides intervening between the 5' and 3' halves of the base-pair increases. Conclusion Our analysis indicates that the current set of nearest-neighbor energy parameters in conjunction with the Mfold folding algorithm are unable to consistently and reliably predict an RNA's correct secondary structure. For 16S or 23S rRNA structure prediction, Mfold 3.1 offers little improvement over Mfold 2.3. However, the nearest-neighbor energy parameters do work well for shorter RNA sequences such as tRNA or 5S rRNA, or for larger rRNAs when the contact distance between the base-pairs is less than 100 nucleotides.

  5. Secondary structure prediction for complete rDNA sequences (18S, 5.8S, and 28S rDNA) of Demodex folliculorum, and comparison of divergent domains structures across Acari.

    Science.gov (United States)

    Zhao, Ya-E; Wang, Zheng-Hang; Xu, Yang; Wu, Li-Ping; Hu, Li

    2013-10-01

    According to base pairing, the rRNA folds into corresponding secondary structures, which contain additional phylogenetic information. On the basis of sequencing for complete rDNA sequences (18S, ITS1, 5.8S, ITS2 and 28S rDNA) of Demodex, we predicted the secondary structure of the complete rDNA sequence (18S, 5.8S, and 28S rDNA) of Demodex folliculorum, which was in concordance with that of the main arthropod lineages in past studies. And together with the sequence data from GenBank, we also predicted the secondary structures of divergent domains in SSU rRNA of 51 species and in LSU rRNA of 43 species from four superfamilies in Acari (Cheyletoidea, Tetranychoidea, Analgoidea and Ixodoidea). The multiple alignment among the four superfamilies in Acari showed that, insertions from Tetranychoidea SSU rRNA formed two newly proposed helixes, and helix c3-2b of LSU rRNA was absent in Demodex (Cheyletoidea) taxa. Generally speaking, LSU rRNA presented more remarkable differences than SSU rRNA did, mainly in D2, D3, D5, D7a, D7b, D8 and D10. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. RNA secondary structure prediction using soft computing.

    Science.gov (United States)

    Ray, Shubhra Sankar; Pal, Sankar K

    2013-01-01

    Prediction of RNA structure is invaluable in creating new drugs and understanding genetic diseases. Several deterministic algorithms and soft computing-based techniques have been developed for more than a decade to determine the structure from a known RNA sequence. Soft computing gained importance with the need to get approximate solutions for RNA sequences by considering the issues related with kinetic effects, cotranscriptional folding, and estimation of certain energy parameters. A brief description of some of the soft computing-based techniques, developed for RNA secondary structure prediction, is presented along with their relevance. The basic concepts of RNA and its different structural elements like helix, bulge, hairpin loop, internal loop, and multiloop are described. These are followed by different methodologies, employing genetic algorithms, artificial neural networks, and fuzzy logic. The role of various metaheuristics, like simulated annealing, particle swarm optimization, ant colony optimization, and tabu search is also discussed. A relative comparison among different techniques, in predicting 12 known RNA secondary structures, is presented, as an example. Future challenging issues are then mentioned.

  7. Enumerating secondary structures and structural moieties for circular RNAs.

    Science.gov (United States)

    Cuesta, Jose A; Manrubia, Susanna

    2017-04-21

    A quantitative characterization of the relationship between molecular sequence and structure is essential to improve our understanding of how function emerges. This particular genotype-phenotype map has been often studied in the context of RNA sequences, with the folded configurations standing as a proxy for the phenotype. Here, we count the secondary structures of circular RNAs of length n and calculate the asymptotic distributions of different structural moieties, such as stems or hairpin loops, by means of symbolic combinatorics. Circular RNAs differ in essential ways from their linear counterparts. From the mathematical viewpoint, the enumeration of the corresponding secondary structures demands the use of combinatorial techniques additional to those used for linear RNAs. The asymptotic number of secondary structures for circular RNAs grows as a(n)n(-5/2), with a depending on particular constraints applied to the secondary structure. As it occurs with linear RNA, the abundance of any structural moiety is normally distributed in the limit n→∞, with a mean and a variance that increase linearly with n. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Supramolecular Multiblock Copolymers Featuring Complex Secondary Structures.

    Science.gov (United States)

    Elacqua, Elizabeth; Manning, Kylie B; Lye, Diane S; Pomarico, Scott K; Morgia, Federica; Weck, Marcus

    2017-09-06

    This contribution introduces main-chain supramolecular ABC and ABB'A block copolymers sustained by orthogonal metal coordination and hydrogen bonding between telechelic polymers that feature distinct secondary structure motifs. Controlled polymerization techniques in combination with supramolecular assembly are used to engineer heterotelechelic π-sheets that undergo high-fidelity association with both helical and coil-forming synthetic polymers. Our design features multiple advances to achieve our targeted structures, in particular, those emulating sheet-like structural aspects using poly(p-phenylenevinylene)s (PPVs). To engineer heterotelechelic PPVs in a sheet-like design, we engineer an iterative one-pot cross metathesis-ring-opening metathesis polymerization (CM-ROMP) strategy that affords functionalized Grubbs-II initiators that subsequently polymerize a paracyclophanediene. Supramolecular assembly of two heterotelechelic PPVs is used to realize a parallel π-sheet, wherein further orthogonal assembly with helical motifs is possible. We also construct an antiparallel π-sheet, wherein terminal PPV blocks are adjacent to a flexible coil-like poly(norbornene) (PNB). The PNB is designed, through supramolecular chain collapse, to expose benzene and perfluorobenzene motifs that promote a hairpin turn via charge-transfer-aided folding. We demonstrate that targeted helix-(π-sheet)-helix and helix-(π-sheet)-coil assemblies occur without compromising intrinsic helicity, while both parallel and antiparallel β-sheet-like structures are realized. Our main-chain orthogonal assembly approach allows the engineering of multiblock copolymer scaffolds featuring diverse secondary structures via the directional assembly of telechelic building blocks. The targeted assemblies, a mix of sequence-defined helix-sheet-coil and helix-sheet-helix architectures, are Nature-inspired synthetic mimics that expose α/β and α+β protein classes via de novo design and cooperative assembly

  9. Drawing and editing the secondary structure(s) of RNA.

    Science.gov (United States)

    Ponty, Yann; Leclerc, Fabrice

    2015-01-01

    Secondary structure diagrams are essential, in RNA biology, to communicate functional hypotheses and summarize structural data, and communicate them visually as drafts or finalized publication-ready figures. While many tools are currently available to automate the production of such diagrams, their capacities are usually partial, making it hard for a user to decide which to use in a given context. In this chapter, we guide the reader through the steps involved in the production of expressive publication-quality illustrations featuring the RNA secondary structure. We present major existing representations and layouts, and give precise instructions to produce them using available free software, including jViz.RNA, the PseudoViewer, RILogo, R-chie, RNAplot, R2R, and VARNA. We describe the file formats and structural descriptions accepted by popular RNA visualization tools. We also provide command lines and Python scripts to ease the user's access to advanced features. Finally, we discuss and illustrate alternative approaches to visualize the secondary structure in the presence of probing data, pseudoknots, RNA-RNA interactions, and comparative data.

  10. Structural Rearrangements in the Active Site of the Thermus thermophilus 16S rRNA Methyltransferase KsgA in a Binary Complex with 5'-Methylthioadenosine

    Energy Technology Data Exchange (ETDEWEB)

    Demirci, H.; Belardinelli, R; Seri, E; Gregory, S; Gualerzi, C; Dahlberg, A; Jogl, G

    2009-01-01

    Posttranscriptional modification of ribosomal RNA (rRNA) occurs in all kingdoms of life. The S-adenosyl-l-methionine-dependent methyltransferase KsgA introduces the most highly conserved rRNA modification, the dimethylation of A1518 and A1519 of 16S rRNA. Loss of this dimethylation confers resistance to the antibiotic kasugamycin. Here, we report biochemical studies and high-resolution crystal structures of KsgA from Thermus thermophilus. Methylation of 30S ribosomal subunits by T. thermophilus KsgA is more efficient at low concentrations of magnesium ions, suggesting that partially unfolded RNA is the preferred substrate. The overall structure is similar to that of other methyltransferases but contains an additional ?-helix in a novel N-terminal extension. Comparison of the apoenzyme with complex structures with 5?-methylthioadenosine or adenosine bound in the cofactor-binding site reveals novel features when compared with related enzymes. Several mobile loop regions that restrict access to the cofactor-binding site are observed. In addition, the orientation of residues in the substrate-binding site indicates that conformational changes are required for binding two adjacent residues of the substrate rRNA.

  11. Conservation of the primary structure at the 3' end of 18S rRNA from eucaryotic cells.

    Science.gov (United States)

    Hagenbüchle, O; Santer, M; Steitz, J A; Mans, R J

    1978-03-01

    DNA sequencing methods have been used to determine a sequence of about 20 nucleotides at the 3' termini of various 18S (small ribosomal subunit) RNA molecules. Polyadenylated rRNA was first synthesized using the enzyme ATP:polynucleotidyl transferase from mainze. Then in the presence of an oligonucleotide primer uniquely complementary to the end of each adenylated rRNA, a cDNA copy was produced using AMV reverse transcriptase. In every case, the cDNA transcript was of finite size, which we ascribe to the appearance of an oligonucleotide containing m62A near the 3' end of the 18S rRNAs. Sequences at the 3' termini of 18S rRNA molecules from the four eucaryotic species examined here (mouse, silk worm, wheat embryo and slime mold) are highly conserved. They also exhibit strong homology to the 3' end of E. coli 16S rRNA. Two important differences, however, are apparent. First, the 16S sequence CCUCC, implicated in mRNA binding by E. coli ribosomes, is absent from each eucaryotic rRNA sequence. Second, a purine-rich region which exhibits extensive complementarity to the 5' noncoding regions of many eucaryotic mRNAs appears consistently.

  12. Diversity of 23S rRNA genes within individual prokaryotic genomes.

    Directory of Open Access Journals (Sweden)

    Anna Pei

    Full Text Available BACKGROUND: The concept of ribosomal constraints on rRNA genes is deduced primarily based on the comparison of consensus rRNA sequences between closely related species, but recent advances in whole-genome sequencing allow evaluation of this concept within organisms with multiple rRNA operons. METHODOLOGY/PRINCIPAL FINDINGS: Using the 23S rRNA gene as an example, we analyzed the diversity among individual rRNA genes within a genome. Of 184 prokaryotic species containing multiple 23S rRNA genes, diversity was observed in 113 (61.4% genomes (mean 0.40%, range 0.01%-4.04%. Significant (1.17%-4.04% intragenomic variation was found in 8 species. In 5 of the 8 species, the diversity in the primary structure had only minimal effect on the secondary structure (stem versus loop transition. In the remaining 3 species, the diversity significantly altered local secondary structure, but the alteration appears minimized through complex rearrangement. Intervening sequences (IVS, ranging between 9 and 1471 nt in size, were found in 7 species. IVS in Deinococcus radiodurans and Nostoc sp. encode transposases. T. tengcongensis was the only species in which intragenomic diversity >3% was observed among 4 paralogous 23S rRNA genes. CONCLUSIONS/SIGNIFICANCE: These findings indicate tight ribosomal constraints on individual 23S rRNA genes within a genome. Although classification using primary 23S rRNA sequences could be erroneous, significant diversity among paralogous 23S rRNA genes was observed only once in the 184 species analyzed, indicating little overall impact on the mainstream of 23S rRNA gene-based prokaryotic taxonomy.

  13. Crystal Structure of the 23S rRNA Fragment Specific to r-Protein L1 and Designed Model of the Ribosomal L1 Stalk from Haloarcula marismortui

    Directory of Open Access Journals (Sweden)

    Azat Gabdulkhakov

    2017-02-01

    Full Text Available The crystal structure of the 92-nucleotide L1-specific fragment of 23S rRNA from Haloarcula marismortui (Hma has been determined at 3.3 Å resolution. Similar to the corresponding bacterial rRNA fragments, this structure contains joined helix 76-77 topped by an approximately globular structure formed by the residual part of the L1 stalk rRNA. The position of HmaL1 relative to the rRNA was found by its docking to the rRNA fragment using the L1-rRNA complex from Thermus thermophilus as a guide model. In spite of the anomalous negative charge of the halophilic archaeal protein, the conformation of the HmaL1-rRNA interface appeared to be very close to that observed in all known L1-rRNA complexes. The designed structure of the L1 stalk was incorporated into the H. marismortui 50S ribosomal subunit. Comparison of relative positions of L1 stalks in 50S subunits from H. marismortui and T. thermophilus made it possible to reveal the site of inflection of rRNA during the ribosome function.

  14. Prediction of protein folding rates from simplified secondary structure alphabet.

    Science.gov (United States)

    Huang, Jitao T; Wang, Titi; Huang, Shanran R; Li, Xin

    2015-10-21

    Protein folding is a very complicated and highly cooperative dynamic process. However, the folding kinetics is likely to depend more on a few key structural features. Here we find that secondary structures can determine folding rates of only large, multi-state folding proteins and fails to predict those for small, two-state proteins. The importance of secondary structures for protein folding is ordered as: extended β strand > α helix > bend > turn > undefined secondary structure>310 helix > isolated β strand > π helix. Only the first three secondary structures, extended β strand, α helix and bend, can achieve a good correlation with folding rates. This suggests that the rate-limiting step of protein folding would depend upon the formation of regular secondary structures and the buckling of chain. The reduced secondary structure alphabet provides a simplified description for the machine learning applications in protein design. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Population genetic structure of Cheyletus malaccensis (Acari: Cheyletidae) in China based on mitochondrial COI and 12S rRNA genes.

    Science.gov (United States)

    Yang, Xiaoqiang; Ye, Qingtian; Xin, Tianrong; Zou, Zhiwen; Xia, Bin

    2016-06-01

    Cheyletus malaccensis is a predatory mite widely distributed in grain storages. It has been regarded as an important biological control agent for pest mites. In this study, we investigated the population genetic structure of C. malaccensis distributed in China based on the partial regions of mitochondrial COI and 12S rRNA genes. We collected 256 individuals of C. malaccensis from stored grain in 34 sites of China. We detected 50 COI gene haplotypes and nine 12S rRNA gene haplotypes. There were three clades in the haplotype network and Bayesian and maximum parsimony phylogenetic trees based on COI sequences, and two based on 12S rRNA sequences. The clustering of haplotypes was not correlated with their geographical distributions. The analysis of molecular variance, AMOVA, indicated that the genetic differentiation between populations was relatively weak. The major genetic differentiation was found within populations. We suggest that the genetic structure of C. malaccensis observed in this study may be the result of long-term climate fluctuations and recent human disturbances.

  16. Neural network definitions of highly predictable protein secondary structure classes

    Energy Technology Data Exchange (ETDEWEB)

    Lapedes, A. [Los Alamos National Lab., NM (United States)]|[Santa Fe Inst., NM (United States); Steeg, E. [Toronto Univ., ON (Canada). Dept. of Computer Science; Farber, R. [Los Alamos National Lab., NM (United States)

    1994-02-01

    We use two co-evolving neural networks to determine new classes of protein secondary structure which are significantly more predictable from local amino sequence than the conventional secondary structure classification. Accurate prediction of the conventional secondary structure classes: alpha helix, beta strand, and coil, from primary sequence has long been an important problem in computational molecular biology. Neural networks have been a popular method to attempt to predict these conventional secondary structure classes. Accuracy has been disappointingly low. The algorithm presented here uses neural networks to similtaneously examine both sequence and structure data, and to evolve new classes of secondary structure that can be predicted from sequence with significantly higher accuracy than the conventional classes. These new classes have both similarities to, and differences with the conventional alpha helix, beta strand and coil.

  17. A novel approach to represent and compare RNA secondary structures

    Science.gov (United States)

    Mattei, Eugenio; Ausiello, Gabriele; Ferrè, Fabrizio; Helmer-Citterich, Manuela

    2014-01-01

    Structural information is crucial in ribonucleic acid (RNA) analysis and functional annotation; nevertheless, how to include such structural data is still a debated problem. Dot-bracket notation is the most common and simple representation for RNA secondary structures but its simplicity leads also to ambiguity requiring further processing steps to dissolve. Here we present BEAR (Brand nEw Alphabet for RNA), a new context-aware structural encoding represented by a string of characters. Each character in BEAR encodes for a specific secondary structure element (loop, stem, bulge and internal loop) with specific length. Furthermore, exploiting this informative and yet simple encoding in multiple alignments of related RNAs, we captured how much structural variation is tolerated in RNA families and convert it into transition rates among secondary structure elements. This allowed us to compute a substitution matrix for secondary structure elements called MBR (Matrix of BEAR-encoded RNA secondary structures), of which we tested the ability in aligning RNA secondary structures. We propose BEAR and the MBR as powerful resources for the RNA secondary structure analysis, comparison and classification, motif finding and phylogeny. PMID:24753415

  18. A combinatorial enumeration problem of RNA secondary structures

    African Journals Online (AJOL)

    use

    2011-12-21

    Dec 21, 2011 ... In 1978, M.S. Waterman firstly gave a mathematical definition of RNA secondary structures (Stein and. Waterman 1978). And in order to satisfy the need of research, RNA secondary structures are usually modeled by some discrete mathematic objects, which establish a connection between Discrete ...

  19. ncRNA consensus secondary structure derivation using grammar strings.

    Science.gov (United States)

    Achawanantakun, Rujira; Sun, Yanni; Takyar, Seyedeh Shohreh

    2011-04-01

    Many noncoding RNAs (ncRNAs) function through both their sequences and secondary structures. Thus, secondary structure derivation is an important issue in today's RNA research. The state-of-the-art structure annotation tools are based on comparative analysis, which derives consensus structure of homologous ncRNAs. Despite promising results from existing ncRNA aligning and consensus structure derivation tools, there is a need for more efficient and accurate ncRNA secondary structure modeling and alignment methods. In this work, we introduce a consensus structure derivation approach based on grammar string, a novel ncRNA secondary structure representation that encodes an ncRNA's sequence and secondary structure in the parameter space of a context-free grammar (CFG) and a full RNA grammar including pseudoknots. Being a string defined on a special alphabet constructed from a grammar, grammar string converts ncRNA alignment into sequence alignment. We derive consensus secondary structures from hundreds of ncRNA families from BraliBase 2.1 and 25 families containing pseudoknots using grammar string alignment. Our experiments have shown that grammar string-based structure derivation competes favorably in consensus structure quality with Murlet and RNASampler. Source code and experimental data are available at http://www.cse.msu.edu/~yannisun/grammar-string.

  20. Recognition determinants for proteins and antibiotics within 23S rRNA

    DEFF Research Database (Denmark)

    Douthwaite, Stephen Roger; Voldborg, Bjørn Gunnar Rude; Hansen, Lykke Haastrup

    1995-01-01

    Ribosomal RNAs fold into phylogenetically conserved secondary and tertiary structures that determine their function in protein synthesis. We have investigated Escherichia coli 23S rRNA to identify structural elements that interact with antibiotic and protein ligands. Using a combination of molecu......Ribosomal RNAs fold into phylogenetically conserved secondary and tertiary structures that determine their function in protein synthesis. We have investigated Escherichia coli 23S rRNA to identify structural elements that interact with antibiotic and protein ligands. Using a combination......-proteins L10.(L12)4 and L11 and is inhibited by interaction with the antibiotic thiostrepton. The peptidyltransferase center within domain V is inhibited by macrolide, lincosamide, and streptogramin B antibiotics, which interact with the rRNA around nucleotide A2058. Drug resistance is conferred by mutations...

  1. Simultaneous prediction of protein secondary structure and transmembrane spans.

    Science.gov (United States)

    Leman, Julia Koehler; Mueller, Ralf; Karakas, Mert; Woetzel, Nils; Meiler, Jens

    2013-07-01

    Prediction of transmembrane spans and secondary structure from the protein sequence is generally the first step in the structural characterization of (membrane) proteins. Preference of a stretch of amino acids in a protein to form secondary structure and being placed in the membrane are correlated. Nevertheless, current methods predict either secondary structure or individual transmembrane states. We introduce a method that simultaneously predicts the secondary structure and transmembrane spans from the protein sequence. This approach not only eliminates the necessity to create a consensus prediction from possibly contradicting outputs of several predictors but bears the potential to predict conformational switches, i.e., sequence regions that have a high probability to change for example from a coil conformation in solution to an α-helical transmembrane state. An artificial neural network was trained on databases of 177 membrane proteins and 6048 soluble proteins. The output is a 3 × 3 dimensional probability matrix for each residue in the sequence that combines three secondary structure types (helix, strand, coil) and three environment types (membrane core, interface, solution). The prediction accuracies are 70.3% for nine possible states, 73.2% for three-state secondary structure prediction, and 94.8% for three-state transmembrane span prediction. These accuracies are comparable to state-of-the-art predictors of secondary structure (e.g., Psipred) or transmembrane placement (e.g., OCTOPUS). The method is available as web server and for download at www.meilerlab.org. Copyright © 2013 Wiley Periodicals, Inc.

  2. Prediction of the secondary structure of HIV-1 gp120

    DEFF Research Database (Denmark)

    Hansen, J E; Lund, O; Nielsen, Jens Ole

    1996-01-01

    strain BH10 gp120, as well as in 27 other HIV-1 strains examined. Two helical segments were predicted in regions displaying profound sequence variation, one in a region suggested to be critical for CD4 binding. The predicted content of helix, beta-strand, and coil was consistent with estimates from......The secondary structure of HIV-1 gp120 was predicted using multiple alignment and a combination of two independent methods based on neural network and nearest-neighbor algorithms. The methods agreed on the secondary structure for 80% of the residues in BH10 gp120. Six helices were predicted in HIV...... Fourier transform infrared spectroscopy. The predicted secondary structure of gp120 compared well with data from NMR analysis of synthetic peptides from the V3 loop and the C4 region. As a first step towards modeling the tertiary structure of gp120, the predicted secondary structure may guide the design...

  3. Identification of consensus RNA secondary structures using suffix arrays

    Directory of Open Access Journals (Sweden)

    Nguyen Truong

    2006-05-01

    Full Text Available Abstract Background The identification of a consensus RNA motif often consists in finding a conserved secondary structure with minimum free energy in an ensemble of aligned sequences. However, an alignment is often difficult to obtain without prior structural information. Thus the need for tools to automate this process. Results We present an algorithm called Seed to identify all the conserved RNA secondary structure motifs in a set of unaligned sequences. The search space is defined as the set of all the secondary structure motifs inducible from a seed sequence. A general-to-specific search allows finding all the motifs that are conserved. Suffix arrays are used to enumerate efficiently all the biological palindromes as well as for the matching of RNA secondary structure expressions. We assessed the ability of this approach to uncover known structures using four datasets. The enumeration of the motifs relies only on the secondary structure definition and conservation only, therefore allowing for the independent evaluation of scoring schemes. Twelve simple objective functions based on free energy were evaluated for their potential to discriminate native folds from the rest. Conclusion Our evaluation shows that 1 support and exclusion constraints are sufficient to make an exhaustive search of the secondary structure space feasible. 2 The search space induced from a seed sequence contains known motifs. 3 Simple objective functions, consisting of a combination of the free energy of matching sequences, can generally identify motifs with high positive predictive value and sensitivity to known motifs.

  4. Combinatorics of RNA Secondary Structures with Base Triples.

    Science.gov (United States)

    Müller, Robert; Nebel, Markus E

    2015-07-01

    The structure of RNA has been the subject of intense research over the last decades due to its importance for the correct functioning of RNA molecules in biological processes. Hence, a large number of models for RNA folding and corresponding algorithms for structure prediction have been developed. However, previous models often only consider base pairs, although every base is capable of up to three edge-to-edge interactions with other bases. Recently, Höner zu Siederdissen et al. presented an extended model of RNA secondary structure, including base triples together with a folding algorithm-the first thermodynamics-based algorithm that allows the prediction of secondary structures with base triples. In this article, we investigate the search space processed by this new algorithm, that is, the combinatorics of extended RNA secondary structures with base triples. We present generalized definitions for structural motifs like hairpins, stems, bulges, or interior loops occurring in structures with base triples. Furthermore, we prove precise asymptotic results for the number of different structures (size of search space) and expectations for various parameters associated with structural motifs (typical shape of folding). Our analysis shows that the asymptotic number of secondary structures of size n increases exponentially to [Formula: see text] compared to the classic model by Stein and Waterman for which [Formula: see text] structures exist. A comparison with the classic model reveals large deviations in the expected structural appearance, too. The inclusion of base triples constitutes a significant refinement of the combinatorial model of RNA secondary structure, which, by our findings, is quantitatively characterized. Our results are of special theoretical interest, because a closer look at the numbers involved suggests that extended RNA secondary structures constitute a new combinatorial class not bijective with any other combinatorial objects studied so far.

  5. Synonymous codon usage in different protein secondary structural ...

    Indian Academy of Sciences (India)

    PRAKASH KUMAR

    2007-06-21

    . The relationship between the synonymous codon usage and different protein secondary structural classes were investigated using 401 Homo sapiens proteins extracted from Protein Data Bank (PDB). A simple Chi-square ...

  6. Neural Network Algorithm for Prediction of Secondary Protein Structure

    National Research Council Canada - National Science Library

    Zikrija Avdagic; Elvir Purisevic; Emir Buza; Zlatan Coralic

    2009-01-01

    .... In this paper we describe the method and results of using CB513 as a dataset suitable for development of artificial neural network algorithms for prediction of secondary protein structure with MATLAB...

  7. A method for rapid similarity analysis of RNA secondary structures

    Directory of Open Access Journals (Sweden)

    Liu Na

    2006-11-01

    Full Text Available Abstract Background Owing to the rapid expansion of RNA structure databases in recent years, efficient methods for structure comparison are in demand for function prediction and evolutionary analysis. Usually, the similarity of RNA secondary structures is evaluated based on tree models and dynamic programming algorithms. We present here a new method for the similarity analysis of RNA secondary structures. Results Three sets of real data have been used as input for the example applications. Set I includes the structures from 5S rRNAs. Set II includes the secondary structures from RNase P and RNase MRP. Set III includes the structures from 16S rRNAs. Reasonable phylogenetic trees are derived for these three sets of data by using our method. Moreover, our program runs faster as compared to some existing ones. Conclusion The famous Lempel-Ziv algorithm can efficiently extract the information on repeated patterns encoded in RNA secondary structures and makes our method an alternative to analyze the similarity of RNA secondary structures. This method will also be useful to researchers who are interested in evolutionary analysis.

  8. Bayesian model of protein primary sequence for secondary structure prediction.

    Directory of Open Access Journals (Sweden)

    Qiwei Li

    Full Text Available Determining the primary structure (i.e., amino acid sequence of a protein has become cheaper, faster, and more accurate. Higher order protein structure provides insight into a protein's function in the cell. Understanding a protein's secondary structure is a first step towards this goal. Therefore, a number of computational prediction methods have been developed to predict secondary structure from just the primary amino acid sequence. The most successful methods use machine learning approaches that are quite accurate, but do not directly incorporate structural information. As a step towards improving secondary structure reduction given the primary structure, we propose a Bayesian model based on the knob-socket model of protein packing in secondary structure. The method considers the packing influence of residues on the secondary structure determination, including those packed close in space but distant in sequence. By performing an assessment of our method on 2 test sets we show how incorporation of multiple sequence alignment data, similarly to PSIPRED, provides balance and improves the accuracy of the predictions. Software implementing the methods is provided as a web application and a stand-alone implementation.

  9. RNA secondary structure image - fRNAdb | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available 10.18908/lsdba.nbdc00452-005 Description of data contents RNA secondary structure images - png.zip: RNA secondary structure images... (PNG) - pdf.zip: RNA secondary structure images (PDF) - thumbnail.zip: Thumbnails of... RNA secondary structure images Data file File name: RNA_secondary_structure_imag

  10. Predicting RNA secondary structures from sequence and probing data.

    Science.gov (United States)

    Lorenz, Ronny; Wolfinger, Michael T; Tanzer, Andrea; Hofacker, Ivo L

    2016-07-01

    RNA secondary structures have proven essential for understanding the regulatory functions performed by RNA such as microRNAs, bacterial small RNAs, or riboswitches. This success is in part due to the availability of efficient computational methods for predicting RNA secondary structures. Recent advances focus on dealing with the inherent uncertainty of prediction by considering the ensemble of possible structures rather than the single most stable one. Moreover, the advent of high-throughput structural probing has spurred the development of computational methods that incorporate such experimental data as auxiliary information. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  11. Combining neural networks for protein secondary structure prediction

    DEFF Research Database (Denmark)

    Riis, Søren Kamaric

    1995-01-01

    In this paper structured neural networks are applied to the problem of predicting the secondary structure of proteins. A hierarchical approach is used where specialized neural networks are designed for each structural class and then combined using another neural network. The submodels are designed...... by using a priori knowledge of the mapping between protein building blocks and the secondary structure and by using weight sharing. Since none of the individual networks have more than 600 adjustable weights over-fitting is avoided. When ensembles of specialized experts are combined the performance...

  12. Protein secondary structure: category assignment and predictability

    DEFF Research Database (Denmark)

    Andersen, Claus A.; Bohr, Henrik; Brunak, Søren

    2001-01-01

    structures. Single sequence prediction of the new three category assignment gives an overall prediction improvement of 3.1% and 5.1%, compared to the DSSP assignment and schemes where the helix category consists of a-helix and 3(10)-helix, respectively. These results were achieved using a standard feed-forward...

  13. Principles for Predicting RNA Secondary Structure Design Difficulty.

    Science.gov (United States)

    Anderson-Lee, Jeff; Fisker, Eli; Kosaraju, Vineet; Wu, Michelle; Kong, Justin; Lee, Jeehyung; Lee, Minjae; Zada, Mathew; Treuille, Adrien; Das, Rhiju

    2016-02-27

    Designing RNAs that form specific secondary structures is enabling better understanding and control of living systems through RNA-guided silencing, genome editing and protein organization. Little is known, however, about which RNA secondary structures might be tractable for downstream sequence design, increasing the time and expense of design efforts due to inefficient secondary structure choices. Here, we present insights into specific structural features that increase the difficulty of finding sequences that fold into a target RNA secondary structure, summarizing the design efforts of tens of thousands of human participants and three automated algorithms (RNAInverse, INFO-RNA and RNA-SSD) in the Eterna massive open laboratory. Subsequent tests through three independent RNA design algorithms (NUPACK, DSS-Opt and MODENA) confirmed the hypothesized importance of several features in determining design difficulty, including sequence length, mean stem length, symmetry and specific difficult-to-design motifs such as zigzags. Based on these results, we have compiled an Eterna100 benchmark of 100 secondary structure design challenges that span a large range in design difficulty to help test future efforts. Our in silico results suggest new routes for improving computational RNA design methods and for extending these insights to assess "designability" of single RNA structures, as well as of switches for in vitro and in vivo applications. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  14. RNAstructure: software for RNA secondary structure prediction and analysis

    Directory of Open Access Journals (Sweden)

    Mathews David H

    2010-03-01

    Full Text Available Abstract Background To understand an RNA sequence's mechanism of action, the structure must be known. Furthermore, target RNA structure is an important consideration in the design of small interfering RNAs and antisense DNA oligonucleotides. RNA secondary structure prediction, using thermodynamics, can be used to develop hypotheses about the structure of an RNA sequence. Results RNAstructure is a software package for RNA secondary structure prediction and analysis. It uses thermodynamics and utilizes the most recent set of nearest neighbor parameters from the Turner group. It includes methods for secondary structure prediction (using several algorithms, prediction of base pair probabilities, bimolecular structure prediction, and prediction of a structure common to two sequences. This contribution describes new extensions to the package, including a library of C++ classes for incorporation into other programs, a user-friendly graphical user interface written in JAVA, and new Unix-style text interfaces. The original graphical user interface for Microsoft Windows is still maintained. Conclusion The extensions to RNAstructure serve to make RNA secondary structure prediction user-friendly. The package is available for download from the Mathews lab homepage at http://rna.urmc.rochester.edu/RNAstructure.html.

  15. Prediction of secondary structural content of proteins from their amino acid composition alone. II. The paradox with secondary structural class.

    Science.gov (United States)

    Eisenhaber, F; Frömmel, C; Argos, P

    1996-06-01

    The success rates reported for secondary structural class prediction with different methods are contradictory. On one side, the problem of recognizing the secondary structural class of a protein knowing only its amino acid composition appears completely solved by simply applying jury decision with an elliptically scaled distance function. Chou and coworkers repeatedly (see Crit. Rev. Biochem. Mol. Biol. 30:275-349, 1995) published prediction accuracies near 100%. On the other hand, traditional secondary structure prediction techniques achieve success rates of about 70% for the secondary structural state per residue and about 75% for structural class only with extensive input information (full sequence of the query protein, its amino acid composition and length, multiple alignments with homologous sequences). In this article, we resolve the paradox and consider (1) the question of the secondary structural class definition, (2) the role of the representativity of the test set of protein tertiary structure for the current state of the Protein Data Bank (PDB); and (3) we estimate the real impact of amino acid composition on secondary structural class. We formulate three objective criteria for a reasonable definition of secondary structural classes and show that only the criterion of Nakashima et al. (J. Biochem. 99:153-162, 1986) complies with all of them. Only this definition matches the distribution of secondary structural content in representative PDB subsets, whereas other criteria leave many proteins (up to 65% of all PDB entries) simply unassigned. We review critically specialized secondary-structural class prediction methods, especially those of Chou and coworkers, which claim almost 100% accuracy using only amino acid composition, and resolve the paradox that these prediction accuracies are better than those from secondary structure predictions from multiple alignments. We show (i) that these techniques rely on a preselection of test sets which removes

  16. The 5'-3' Distance of RNA Secondary Structures

    DEFF Research Database (Denmark)

    Han, Hillary S W; Reidys, Christian

    2012-01-01

    Abstract Recently, Yoffe and colleagues observed that the average distances between 5'-3' ends of RNA molecules are very small and largely independent of sequence length. This observation is based on numerical computations as well as theoretical arguments maximizing certain entropy functionals....... In this article, we compute the exact distribution of 5'-3' distances of RNA secondary structures for any finite n. Furthermore, we compute the limit distribution and show that for n = 30 the exact distribution and the limit distribution are very close. Our results show that the distances of random RNA secondary...... structures are distinctively lower than those of minimum free energy structures of random RNA sequences....

  17. Use of secondary structural information and Cα-Cα distance ...

    Indian Academy of Sciences (India)

    PRAKASH KUMAR

    2007-06-21

    Jun 21, 2007 ... Q3 (alpha-helix, beta-strands and irregular turns/loops) secondary structure information, along with residue-residue contact information as ... for the proteins which have high percent of alpha-helix content. This analysis further ..... nucleation of the structure in the protein folding process. The SRP set of ...

  18. Original Paper Floristic and structural changes in secondary forests ...

    African Journals Online (AJOL)

    Structural changes in secondary forests are less known in West Africa, and this precludes their management. .... Sampling design and data collection. Seventy seven ...... Impacts of selective logging and agricultural clearing on forest structure, floristic composition and diversity, and timber tree regeneration in the Ituri Forest,.

  19. RNA secondary structure diagrams for very large molecules: RNAfdl

    DEFF Research Database (Denmark)

    Hecker, Nikolai; Wiegels, Tim; Torda, Andrew E.

    2013-01-01

    There are many programs that can read the secondary structure of an RNA molecule and draw a diagram, but hardly any that can cope with 10 3 bases. RNAfdl is slow but capable of producing intersection-free diagrams for ribosome-sized structures, has a graphical user interface for adjustments and p...

  20. 5S rRNA and ribosome.

    Science.gov (United States)

    Gongadze, G M

    2011-12-01

    5S rRNA is an integral component of the ribosome of all living organisms. It is known that the ribosome without 5S rRNA is functionally inactive. However, the question about the specific role of this RNA in functioning of the translation apparatus is still open. This review presents a brief history of the discovery of 5S rRNA and studies of its origin and localization in the ribosome. The previously expressed hypotheses about the role of this RNA in the functioning of the ribosome are discussed considering the unique location of 5S rRNA in the ribosome and its intermolecular contacts. Based on analysis of the current data on ribosome structure and its functional complexes, the role of 5S rRNA as an intermediary between ribosome functional domains is discussed.

  1. BRASERO: A Resource for Benchmarking RNA Secondary Structure Comparison Algorithms

    Directory of Open Access Journals (Sweden)

    Julien Allali

    2012-01-01

    Full Text Available The pairwise comparison of RNA secondary structures is a fundamental problem, with direct application in mining databases for annotating putative noncoding RNA candidates in newly sequenced genomes. An increasing number of software tools are available for comparing RNA secondary structures, based on different models (such as ordered trees or forests, arc annotated sequences, and multilevel trees and computational principles (edit distance, alignment. We describe here the website BRASERO that offers tools for evaluating such software tools on real and synthetic datasets.

  2. Prediction of the secondary structure of HIV-1 gp120

    DEFF Research Database (Denmark)

    Hansen, J E; Lund, O; Nielsen, Jens Ole

    1996-01-01

    The secondary structure of HIV-1 gp120 was predicted using multiple alignment and a combination of two independent methods based on neural network and nearest-neighbor algorithms. The methods agreed on the secondary structure for 80% of the residues in BH10 gp120. Six helices were predicted in HIV...... strain BH10 gp120, as well as in 27 other HIV-1 strains examined. Two helical segments were predicted in regions displaying profound sequence variation, one in a region suggested to be critical for CD4 binding. The predicted content of helix, beta-strand, and coil was consistent with estimates from...... of future HIV subunit vaccine candidates....

  3. Prediction of the Secondary Structure of HIV-1 gp120

    DEFF Research Database (Denmark)

    Hansen, Jan; Lund, Ole; Nielsen, Jens O.

    1996-01-01

    The secondary structure of HIV-1 gp120 was predicted using multiple alignment and a combination of two independent methods based on neural network and nearest-neighbor algorithms. The methods agreed on the secondary structure for 80% of the residues in BH10 gp120. Six helices were predicted in HIV...... strain BH10 gp120, as well as in 27 other HIV-1 strains examined. Two helical seqments were predicted in regions displaying profound sequence variation, one in a region suggested to be critical for CD4 biding. The predicted content of helix, beta-strand, and coil was consistent with estimates from...... of future HIV sub-unit vaccine candidates....

  4. RNA secondary structure prediction using highly parallel computers.

    Science.gov (United States)

    Nakaya, A; Yamamoto, K; Yonezawa, A

    1995-12-01

    An RNA secondary structure prediction method using a highly parallel computer is reported. We focus on finding thermodynamically stable structures of a single-stranded RNA molecule. Our approach is based on a parallel combinatorial method which calculates the free energy of a molecule as the sum of the free energies of all the physically possible hydrogen bonds. Our parallel algorithm finds many highly stable structures all at once, while most of the conventional prediction methods find only the most stable structure. The important idea in our algorithm is search tree pruning, with dynamic load balancing across the processor elements in a parallel computer. Software tools for visualization and classification of secondary structures are also presented using the sequence of cadang-cadang coconut viroid as an example. Our software system runs on CM-5.

  5. Using chemical shifts to assess transient secondary structure and generate ensemble structures of intrinsically disordered proteins.

    Science.gov (United States)

    Kashtanov, Stepan; Borcherds, Wade; Wu, Hongwei; Daughdrill, Gary W; Ytreberg, F Marty

    2012-01-01

    The chemical shifts of backbone atoms in polypeptides are sensitive to the dihedral angles phi and psi and can be used to estimate transient secondary structure and to generate structural ensembles of intrinsically disordered proteins (IDPs). In this chapter, several of the random coil reference databases used to estimate transient secondary structure are described, and the procedure is outlined for using these databases to estimate transient secondary structure. A new protocol is also presented for generating a diverse ensemble of structures for an IDP and reweighting these structures to optimize the fit between simulated and experimental chemical shift values.

  6. Ensemble-based prediction of RNA secondary structures.

    Science.gov (United States)

    Aghaeepour, Nima; Hoos, Holger H

    2013-04-24

    Accurate structure prediction methods play an important role for the understanding of RNA function. Energy-based, pseudoknot-free secondary structure prediction is one of the most widely used and versatile approaches, and improved methods for this task have received much attention over the past five years. Despite the impressive progress that as been achieved in this area, existing evaluations of the prediction accuracy achieved by various algorithms do not provide a comprehensive, statistically sound assessment. Furthermore, while there is increasing evidence that no prediction algorithm consistently outperforms all others, no work has been done to exploit the complementary strengths of multiple approaches. In this work, we present two contributions to the area of RNA secondary structure prediction. Firstly, we use state-of-the-art, resampling-based statistical methods together with a previously published and increasingly widely used dataset of high-quality RNA structures to conduct a comprehensive evaluation of existing RNA secondary structure prediction procedures. The results from this evaluation clarify the performance relationship between ten well-known existing energy-based pseudoknot-free RNA secondary structure prediction methods and clearly demonstrate the progress that has been achieved in recent years. Secondly, we introduce AveRNA, a generic and powerful method for combining a set of existing secondary structure prediction procedures into an ensemble-based method that achieves significantly higher prediction accuracies than obtained from any of its component procedures. Our new, ensemble-based method, AveRNA, improves the state of the art for energy-based, pseudoknot-free RNA secondary structure prediction by exploiting the complementary strengths of multiple existing prediction procedures, as demonstrated using a state-of-the-art statistical resampling approach. In addition, AveRNA allows an intuitive and effective control of the trade-off between

  7. PASSML: combining evolutionary inference and protein secondary structure prediction.

    Science.gov (United States)

    Liò, P; Goldman, N; Thorne, J L; Jones3, D T

    1998-01-01

    Evolutionary models of amino acid sequences can be adapted to incorporate structure information; protein structure biologists can use phylogenetic relationships among species to improve prediction accuracy. Results : A computer program called PASSML ('Phylogeny and Secondary Structure using Maximum Likelihood') has been developed to implement an evolutionary model that combines protein secondary structure and amino acid replacement. The model is related to that of Dayhoff and co-workers, but we distinguish eight categories of structural environment: alpha helix, beta sheet, turn and coil, each further classified according to solvent accessibility, i.e. buried or exposed. The model of sequence evolution for each of the eight categories is a Markov process with discrete states in continuous time, and the organization of structure along protein sequences is described by a hidden Markov model. This paper describes the PASSML software and illustrates how it allows both the reconstruction of phylogenies and prediction of secondary structure from aligned amino acid sequences. PASSML 'ANSI C' source code and the example data sets described here are available at http://ng-dec1.gen.cam.ac.uk/hmm/Passml.html and 'downstream' Web pages. P.Lio@gen.cam.ac.uk

  8. G-quadruplex secondary structure from circular dichroism spectroscopy.

    Science.gov (United States)

    Del Villar-Guerra, Rafael; Trent, John O; Chaires, Jonathan B

    2017-10-26

    A curated library of circular dichroism spectra of 23 G-quadruplexes of known structure was built and analyzed. The goal of this study was to use this reference library to develop an algorithm to derive quantitative estimates of the secondary structure content of quadruplexes from their experimental CD spectra. Principal component analysis and singular value decomposition were used to characterize the reference spectral library. CD spectra were successfully fit to obtain estimates of the amounts of base steps in anti-anti, syn-anti or anti-syn conformations, in diagonal or lateral loops or in other conformations. The results show that CD spectra of nucleic acids can be analyzed to obtain quantitative structural information about secondary structure content in an analogous way to methods used to analyze protein CD spectra. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Approaches to link RNA secondary structures with splicing regulation

    DEFF Research Database (Denmark)

    Plass, Mireya; Eyras, Eduardo

    2014-01-01

    In higher eukaryotes, alternative splicing is usually regulated by protein factors, which bind to the pre-mRNA and affect the recognition of splicing signals. There is recent evidence that the secondary structure of the pre-mRNA may also play an important role in this process, either by facilitat...

  10. General enumeration of RNA secondary structures based on new ...

    African Journals Online (AJOL)

    Crick base pairs between AU and GC. Based on the new representation, this paper also computes the number of various types of constrained secondary structures taking the minimum stack length 1 and minimum size m for each bonding loop as ...

  11. Secondary Structures Associated With Alkaline Transition of Horse ...

    African Journals Online (AJOL)

    The spectra of amide I region (1700-1600cm-1) of horse heart ferricytochrome c at 20oC are reported at low ionic strength at of pH values between 7.0 and 11.5 encompassing the alkaline transition. The mid-infrared spectra can probe the protein secondary structures. The Fourier transform infrared spectroscopic technique ...

  12. A phase transition in energy-filtered RNA secondary structures

    DEFF Research Database (Denmark)

    Han, Hillary Siwei; reidys, Christian

    2012-01-01

    In this paper we study the effect of energy parameters on minimum free energy (mfe) RNA secondary structures. Employing a simplified combinatorial energy model, that is only dependent on the diagram representation and that is not sequence specific, we prove the following dichotomy result. Mfe str...

  13. Highly divergent 16S rRNA sequences in ribosomal operons of Scytonema hyalinum (Cyanobacteria.

    Directory of Open Access Journals (Sweden)

    Jeffrey R Johansen

    Full Text Available A highly divergent 16S rRNA gene was found in one of the five ribosomal operons present in a species complex currently circumscribed as Scytonema hyalinum (Nostocales, Cyanobacteria using clone libraries. If 16S rRNA sequence macroheterogeneity among ribosomal operons due to insertions, deletions or truncation is excluded, the sequence heterogeneity observed in S. hyalinum was the highest observed in any prokaryotic species thus far (7.3-9.0%. The secondary structure of the 16S rRNA molecules encoded by the two divergent operons was nearly identical, indicating possible functionality. The 23S rRNA gene was examined for a few strains in this complex, and it was also found to be highly divergent from the gene in Type 2 operons (8.7%, and likewise had nearly identical secondary structure between the Type 1 and Type 2 operons. Furthermore, the 16S-23S ITS showed marked differences consistent between operons among numerous strains. Both operons have promoter sequences that satisfy consensus requirements for functional prokaryotic transcription initiation. Horizontal gene transfer from another unknown heterocytous cyanobacterium is considered the most likely explanation for the origin of this molecule, but does not explain the ultimate origin of this sequence, which is very divergent from all 16S rRNA sequences found thus far in cyanobacteria. The divergent sequence is highly conserved among numerous strains of S. hyalinum, suggesting adaptive advantage and selective constraint of the divergent sequence.

  14. Distinct circular dichroism spectroscopic signatures of polyproline II and unordered secondary structures: applications in secondary structure analyses.

    Science.gov (United States)

    Lopes, Jose L S; Miles, Andrew J; Whitmore, Lee; Wallace, B A

    2014-12-01

    Circular dichroism (CD) spectroscopy is a valuable method for defining canonical secondary structure contents of proteins based on empirically-defined spectroscopic signatures derived from proteins with known three-dimensional structures. Many proteins identified as being "Intrinsically Disordered Proteins" have a significant amount of their structure that is neither sheet, helix, nor turn; this type of structure is often classified by CD as "other", "random coil", "unordered", or "disordered". However the "other" category can also include polyproline II (PPII)-type structures, whose spectral properties have not been well-distinguished from those of unordered structures. In this study, synchrotron radiation circular dichroism spectroscopy was used to investigate the spectral properties of collagen and polyproline, which both contain PPII-type structures. Their native spectra were compared as representatives of PPII structures. In addition, their spectra before and after treatment with various conditions to produce unfolded or denatured structures were also compared, with the aim of defining the differences between CD spectra of PPII and disordered structures. We conclude that the spectral features of collagen are more appropriate than those of polyproline for use as the representative spectrum for PPII structures present in typical amino acid-containing proteins, and that the single most characteristic spectroscopic feature distinguishing a PPII structure from a disordered structure is the presence of a positive peak around 220nm in the former but not in the latter. These spectra are now available for inclusion in new reference data sets used for CD analyses of the secondary structures of soluble proteins. © 2014 The Protein Society.

  15. LBA-ECO ND-04 Secondary Forest Recovery, Structure, and LAI, Central Amazonia, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set reports measurements of the canopy and structure of secondary forests regenerating from abandoned pastures. These secondary forests are...

  16. Random generation of RNA secondary structures according to native distributions

    Directory of Open Access Journals (Sweden)

    Nebel Markus E

    2011-10-01

    Full Text Available Abstract Background Random biological sequences are a topic of great interest in genome analysis since, according to a powerful paradigm, they represent the background noise from which the actual biological information must differentiate. Accordingly, the generation of random sequences has been investigated for a long time. Similarly, random object of a more complicated structure like RNA molecules or proteins are of interest. Results In this article, we present a new general framework for deriving algorithms for the non-uniform random generation of combinatorial objects according to the encoding and probability distribution implied by a stochastic context-free grammar. Briefly, the framework extends on the well-known recursive method for (uniform random generation and uses the popular framework of admissible specifications of combinatorial classes, introducing weighted combinatorial classes to allow for the non-uniform generation by means of unranking. This framework is used to derive an algorithm for the generation of RNA secondary structures of a given fixed size. We address the random generation of these structures according to a realistic distribution obtained from real-life data by using a very detailed context-free grammar (that models the class of RNA secondary structures by distinguishing between all known motifs in RNA structure. Compared to well-known sampling approaches used in several structure prediction tools (such as SFold ours has two major advantages: Firstly, after a preprocessing step in time O(n2 for the computation of all weighted class sizes needed, with our approach a set of m random secondary structures of a given structure size n can be computed in worst-case time complexity Om⋅n⋅ log(n while other algorithms typically have a runtime in O(m⋅n2. Secondly, our approach works with integer arithmetic only which is faster and saves us from all the discomforting details of using floating point arithmetic with

  17. Improving the accuracy of protein secondary structure prediction using structural alignment

    Directory of Open Access Journals (Sweden)

    Gallin Warren J

    2006-06-01

    Full Text Available Abstract Background The accuracy of protein secondary structure prediction has steadily improved over the past 30 years. Now many secondary structure prediction methods routinely achieve an accuracy (Q3 of about 75%. We believe this accuracy could be further improved by including structure (as opposed to sequence database comparisons as part of the prediction process. Indeed, given the large size of the Protein Data Bank (>35,000 sequences, the probability of a newly identified sequence having a structural homologue is actually quite high. Results We have developed a method that performs structure-based sequence alignments as part of the secondary structure prediction process. By mapping the structure of a known homologue (sequence ID >25% onto the query protein's sequence, it is possible to predict at least a portion of that query protein's secondary structure. By integrating this structural alignment approach with conventional (sequence-based secondary structure methods and then combining it with a "jury-of-experts" system to generate a consensus result, it is possible to attain very high prediction accuracy. Using a sequence-unique test set of 1644 proteins from EVA, this new method achieves an average Q3 score of 81.3%. Extensive testing indicates this is approximately 4–5% better than any other method currently available. Assessments using non sequence-unique test sets (typical of those used in proteome annotation or structural genomics indicate that this new method can achieve a Q3 score approaching 88%. Conclusion By using both sequence and structure databases and by exploiting the latest techniques in machine learning it is possible to routinely predict protein secondary structure with an accuracy well above 80%. A program and web server, called PROTEUS, that performs these secondary structure predictions is accessible at http://wishart.biology.ualberta.ca/proteus. For high throughput or batch sequence analyses, the PROTEUS programs

  18. Using circular dichroism spectra to estimate protein secondary structure

    Science.gov (United States)

    Greenfield, Norma J.

    2009-01-01

    Circular dichroism (CD) is an excellent tool for rapid determination of the secondary structure and folding properties of proteins that have been obtained using recombinant techniques or purified from tissues. The most widely used applications of protein CD are to determine whether an expressed, purified protein is folded, or if a mutation affects its conformation or stability. In addition, it can be used to study protein interactions. This protocol details the basic steps of obtaining and interpreting CD data and methods for analyzing spectra to estimate the secondary structural composition of proteins. CD has the advantage that it is that measurements may be made on multiple samples containing 20 µg or less of proteins in physiological buffers in a few hours. However, it does not give the residue-specific information that can be obtained by X-ray crystallography or NMR. PMID:17406547

  19. STUDYING THE SECONDARY STRUCTURE OF ACCESSION NUMBER USING CETD MATRIX

    Directory of Open Access Journals (Sweden)

    Anamika Dutta

    2016-10-01

    Full Text Available This paper, we have tried to analyze about the Secondary Structure of nucleotide sequences of rice. The data have been collected from NCBI (National Centre for Biotechnology Information using Nucleotide as data base. All the programs were developed using R programming language using “sequinr” package. Here, we have used CETD matrix method to study the prediction. The conclusions are drawn accordingly.

  20. Evolutionary rate variation and RNA secondary structure prediction

    DEFF Research Database (Denmark)

    Knudsen, B; Andersen, E S; Damgaard, Christian Kroun

    2004-01-01

    of approach. Determining these rates can be hard to do reliably without a large and accurate initial alignment, which ideally also has structural annotation. Hence, one must often apply rates extracted from other RNA families with trusted alignments and structures. Here, we investigate this problem......Predicting RNA secondary structure using evolutionary history can be carried out by using an alignment of related RNA sequences with conserved structure. Accurately determining evolutionary substitution rates for base pairs and single stranded nucleotides is a concern for methods based on this type....... In addition we obtained an alignment of the 5' HIV-1 region that is more consistent with the structure than that currently in the database. We added randomized noise to the original values of the rates to investigate the stability of predictions to rate matrix deviations. We find that changes within a fairly...

  1. Bacterial community structure of mangrove sediments in relation to environmental variables accessed by 16S rRNA gene-denaturing gradient gel electrophoresis fingerprinting

    Directory of Open Access Journals (Sweden)

    Yanying Zhang

    2009-09-01

    Full Text Available Bacterial community structure and the relationship between environmental variables and microbial communities in the surface sediments of tropical mangrove ecosystems were investigated in Sanya, Hainan Island, China. Profiles of bacterial communities were generated using culture-independent PCR-denaturing gradient gel electrophoresis (DGGE, and the results were interpreted with multivariate statistical analysis. Findings suggested that microbial communities varied with sample collection sites and seasons. The samples collected from the same sample sites at the same time had more similar microbial communities except samples SH3 and AB5, which also had unique sediment quality. Canonical correspondence analysis (CCA revealed that the organic carbon concentration of the sediments accounted for a significant amount of the variability in the bacterial community composition. Phylogenetic analysis was used to identify the major groups of the predominant bacterial phylotypes. 16S rRNA gene-V3 fragments from 17 individual DGGE bands were sequenced and the corresponding bacteria were found in mangrove sediments for the first time based on BLAST results. Predominant bacterial phylotypes clustered with various taxonomic groups, including Proteobacteria, Bacteroidetes, Gemmatimonadetes, Actinobacteria and Firmicutes.

  2. Coating concrete secondary containment structures exposed to agrichemicals

    Energy Technology Data Exchange (ETDEWEB)

    Broder, M.F.; Nguyen, D.T.

    1995-06-01

    Concrete has traditionally been the material of choice for building secondary containment structures because it is relatively inexpensive and has structural properties which make it ideal for supporting the loads of vehicles and large tanks. However, concrete`s chemical properties make it susceptible to corrosion by some common fertilizers. Though fairly impervious to water movement, concrete is easily penetrated by vapors and solvents. It is also prone to cracking. For these reasons, the Environmental Protection Agency (EPA) believes that concrete alone may not provide an effective barrier to pesticide movement and has proposed that concrete in pesticide secondary containment structures be sealed or coated to reduce its permeability. Some state secondary containment regulations require that concrete exposed to fertilizers and pesticides be sealed or protected with a coating. Lacking guidelines, some retailers have used penetrating sealants to satisfy the law, even though these products provide little protection from chemical attack nor do they prevent pesticide egress. Other retailers who have applied thick film coatings which were properly selected have had disastrous results because the application was poorly done. Consequently, much skepticism exists regarding the performance and benefit of protective coatings.

  3. A protein structural classes prediction method based on predicted secondary structure and PSI-BLAST profile.

    Science.gov (United States)

    Ding, Shuyan; Li, Yan; Shi, Zhuoxing; Yan, Shoujiang

    2014-02-01

    Knowledge of protein secondary structural classes plays an important role in understanding protein folding patterns. In this paper, 25 features based on position-specific scoring matrices are selected to reflect evolutionary information. In combination with other 11 rational features based on predicted protein secondary structure sequences proposed by the previous researchers, a 36-dimensional representation feature vector is presented to predict protein secondary structural classes for low-similarity sequences. ASTRALtraining dataset is used to train and design our method, other three low-similarity datasets ASTRALtest, 25PDB and 1189 are used to test the proposed method. Comparisons with other methods show that our method is effective to predict protein secondary structural classes. Stand alone version of the proposed method (PSSS-PSSM) is written in MATLAB language and it can be downloaded from http://letsgob.com/bioinfo_PSSS_PSSM/. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  4. Strategies for measuring evolutionary conservation of RNA secondary structures

    Directory of Open Access Journals (Sweden)

    Hofacker Ivo L

    2008-02-01

    Full Text Available Abstract Background Evolutionary conservation of RNA secondary structure is a typical feature of many functional non-coding RNAs. Since almost all of the available methods used for prediction and annotation of non-coding RNA genes rely on this evolutionary signature, accurate measures for structural conservation are essential. Results We systematically assessed the ability of various measures to detect conserved RNA structures in multiple sequence alignments. We tested three existing and eight novel strategies that are based on metrics of folding energies, metrics of single optimal structure predictions, and metrics of structure ensembles. We find that the folding energy based SCI score used in the RNAz program and a simple base-pair distance metric are by far the most accurate. The use of more complex metrics like for example tree editing does not improve performance. A variant of the SCI performed particularly well on highly conserved alignments and is thus a viable alternative when only little evolutionary information is available. Surprisingly, ensemble based methods that, in principle, could benefit from the additional information contained in sub-optimal structures, perform particularly poorly. As a general trend, we observed that methods that include a consensus structure prediction outperformed equivalent methods that only consider pairwise comparisons. Conclusion Structural conservation can be measured accurately with relatively simple and intuitive metrics. They have the potential to form the basis of future RNA gene finders, that face new challenges like finding lineage specific structures or detecting mis-aligned sequences.

  5. PCI-SS: MISO dynamic nonlinear protein secondary structure prediction

    Directory of Open Access Journals (Sweden)

    Aboul-Magd Mohammed O

    2009-07-01

    Full Text Available Abstract Background Since the function of a protein is largely dictated by its three dimensional configuration, determining a protein's structure is of fundamental importance to biology. Here we report on a novel approach to determining the one dimensional secondary structure of proteins (distinguishing α-helices, β-strands, and non-regular structures from primary sequence data which makes use of Parallel Cascade Identification (PCI, a powerful technique from the field of nonlinear system identification. Results Using PSI-BLAST divergent evolutionary profiles as input data, dynamic nonlinear systems are built through a black-box approach to model the process of protein folding. Genetic algorithms (GAs are applied in order to optimize the architectural parameters of the PCI models. The three-state prediction problem is broken down into a combination of three binary sub-problems and protein structure classifiers are built using 2 layers of PCI classifiers. Careful construction of the optimization, training, and test datasets ensures that no homology exists between any training and testing data. A detailed comparison between PCI and 9 contemporary methods is provided over a set of 125 new protein chains guaranteed to be dissimilar to all training data. Unlike other secondary structure prediction methods, here a web service is developed to provide both human- and machine-readable interfaces to PCI-based protein secondary structure prediction. This server, called PCI-SS, is available at http://bioinf.sce.carleton.ca/PCISS. In addition to a dynamic PHP-generated web interface for humans, a Simple Object Access Protocol (SOAP interface is added to permit invocation of the PCI-SS service remotely. This machine-readable interface facilitates incorporation of PCI-SS into multi-faceted systems biology analysis pipelines requiring protein secondary structure information, and greatly simplifies high-throughput analyses. XML is used to represent the input

  6. Visualization of RNA secondary structures using highly parallel computers.

    Science.gov (United States)

    Nakaya, A; Taura, K; Yamamoto, K; Yonezawa, A

    1996-06-01

    Results of RNA secondary structure prediction algorithm are usually given as a set of hydrogen bonds between bases. However, we cannot know the precise structure of an RNA molecule by only knowing which bases form hydrogen bonds. One way to understand the structure of an RNA molecule is to visualize it using a planar graph so that we can easily know the geometric relations among the substructures such as stacking regions and loops. To do this, we consider bases to be particles on a plane and introduce a repulsive force and an attractive force among these particles and determine their positions according to these forces. A naive algorithm requires O(N2) time but we can reduce it to O(NlogN) with an approximation algorithm which is often used in the area of N-body simulation. Our program is written in parallel object-oriented language 'Schematic' which is recently developed. Efficiency of our implementation on a parallel computer and results of visualization of secondary structures are presented using cadang-cadang coconut viroid as an example.

  7. Secondary Metabolites from Acremonium Fungi: Diverse Structures and Bioactivities.

    Science.gov (United States)

    Tian, Jin; Lai, Daowan; Zhou, Ligang

    2017-01-01

    Acremonium fungi have been isolated from various sources, such as soil, plants, and marine organisms. The species in Acremonium have been proved to be rich sources of novel and bioactive secondary metabolites. Up to now, 356 metabolites belonging to steroids (6 compounds), terpenoids (86), meroterpenoids (66), polyketides (89), alkaloids (28), peptides (75), and miscellaneous types (6) have been isolated from Acremonium fungi. These metabolites displayed a wide range of biological activities including antimicrobial, cytotoxic, antitumor, immunosuppressive, antioxidant, antiinflammatory, antimalarial, phytotoxic, tremorgenic, antiviral, neuritogenic, insecticidal and enzymesinhibiting activities. This review highlights the structures and bioactivities of the secondary metabolites from Acremonium fungi reported until July 2016. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  8. The 5S rRNA-histone repeat in the crustacean Artemia: structure, polymorphism and variation of the 5S rRNA segment in different populations.

    Science.gov (United States)

    Cruces, J; Díaz-Guerra, M; Gil, I; Renart, J

    1989-08-11

    5S rRNA genes are linked to the histone genes in the 13 populations of the crustacean Artemia that we have studied. In all cases, two types of repeat units are found. Southern blot analysis of all populations shows that they can be grouped into three classes: a) American bisexuals; b) Eurasian bisexuals, and c) parthenogenetic organisms (all from Eurasia). Restriction analysis of a bisexual population from San Francisco Bay shows that the two repeat units are of 9.0 and 8.5 kb (with minor heterogeneities of restriction sites). In parthenogenetic organisms, the two repeat units are of approximately 12 kb. Sequencing data from the region of the 5S rRNA from the San Francisco Bay population, shows that in both types of units, the single 5S rRNA gene (315 bp in length), is located 430 bp downstream the 3' regulatory sequences of the H2A gene, the last gene in the histone cluster. We have isolated three clones that contain 5S rRNA sequences. Two of them (one from an American bisexual and the other from a parthenogenetic population) contain histone and 5S rRNA genes, both with the same transcriptional polarity. The third clone, lacking histone genes, is likely to be an orphon derived from the parthenogenetic population.

  9. Secondary Structure of Rat and Human Amylin across Force Fields.

    Directory of Open Access Journals (Sweden)

    Kyle Quynn Hoffmann

    Full Text Available The aggregation of human amylin has been strongly implicated in the progression of Type II diabetes. This 37-residue peptide forms a variety of secondary structures, including random coils, α-helices, and β-hairpins. The balance between these structures depends on the chemical environment, making amylin an ideal candidate to examine inherent biases in force fields. Rat amylin differs from human amylin by only 6 residues; however, it does not form fibrils. Therefore it provides a useful complement to human amylin in studies of the key events along the aggregation pathway. In this work, the free energy of rat and human amylin was determined as a function of α-helix and β-hairpin content for the Gromos96 53a6, OPLS-AA/L, CHARMM22/CMAP, CHARMM22*, Amberff99sb*-ILDN, and Amberff03w force fields using advanced sampling techniques, specifically bias exchange metadynamics. This work represents a first systematic attempt to evaluate the conformations and the corresponding free energy of a large, clinically relevant disordered peptide in solution across force fields. The NMR chemical shifts of rIAPP were calculated for each of the force fields using their respective free energy maps, allowing us to quantitatively assess their predictions. We show that the predicted distribution of secondary structures is sensitive to the choice of force-field: Gromos53a6 is biased towards β-hairpins, while CHARMM22/CMAP predicts structures that are overly α-helical. OPLS-AA/L favors disordered structures. Amberff99sb*-ILDN, AmberFF03w and CHARMM22* provide the balance between secondary structures that is most consistent with available experimental data. In contrast to previous reports, our findings suggest that the equilibrium conformations of human and rat amylin are remarkably similar, but that subtle differences arise in transient alpha-helical and beta-strand containing structures that the human peptide can more readily adopt. We hypothesize that these transient

  10. Fourier Analysis of Conservation Patterns in Protein Secondary Structure.

    Science.gov (United States)

    Palaniappan, Ashok; Jakobsson, Eric

    2017-01-01

    Residue conservation is a common observation in alignments of protein families, underscoring positions important in protein structure and function. Though many methods measure the level of conservation of particular residue positions, currently we do not have a way to study spatial oscillations occurring in protein conservation patterns. It is known that hydrophobicity shows spatial oscillations in proteins, which is characterized by computing the hydrophobic moment of the protein domains. Here, we advance the study of moments of conservation of protein families to know whether there might exist spatial asymmetry in the conservation patterns of regular secondary structures. Analogous to the hydrophobic moment, the conservation moment is defined as the modulus of the Fourier transform of the conservation function of an alignment of related protein, where the conservation function is the vector of conservation values at each column of the alignment. The profile of the conservation moment is useful in ascertaining any periodicity of conservation, which might correlate with the period of the secondary structure. To demonstrate the concept, conservation in the family of potassium ion channel proteins was analyzed using moments. It was shown that the pore helix of the potassium channel showed oscillations in the moment of conservation matching the period of the α-helix. This implied that one side of the pore helix was evolutionarily conserved in contrast to its opposite side. In addition, the method of conservation moments correctly identified the disposition of the voltage sensor of voltage-gated potassium channels to form a 310 helix in the membrane.

  11. Insights into the structure, function and evolution of the radical-SAM 23S rRNA methyltransferase Cfr that confers antibiotic resistance in bacteria

    DEFF Research Database (Denmark)

    Karminska, K. H.; Purta, E.; Hansen, L .H.

    2010-01-01

    The Cfr methyltransferase confers combined resistance to five classes of antibiotics that bind to the peptidyl tranferase center of bacterial ribosomes by catalyzing methylation of the C-8 position of 23S rRNA nucleotide A2503. The same nucleotide is targeted by the housekeeping methyltransferase...

  12. RNA Secondary Structure Prediction by Using Discrete Mathematics: An Interdisciplinary Research Experience for Undergraduate Students

    Science.gov (United States)

    Ellington, Roni; Wachira, James; Nkwanta, Asamoah

    2010-01-01

    The focus of this Research Experience for Undergraduates (REU) project was on RNA secondary structure prediction by using a lattice walk approach. The lattice walk approach is a combinatorial and computational biology method used to enumerate possible secondary structures and predict RNA secondary structure from RNA sequences. The method uses…

  13. Overaccumulation of the chloroplast antisense RNA AS5 is correlated with decreased abundance of 5S rRNA in vivo and inefficient 5S rRNA maturation in vitro

    Science.gov (United States)

    Sharwood, Robert E.; Hotto, Amber M.; Bollenbach, Thomas J.; Stern, David B.

    2011-01-01

    Post-transcriptional regulation in the chloroplast is exerted by nucleus-encoded ribonucleases and RNA-binding proteins. One of these ribonucleases is RNR1, a 3′-to-5′ exoribonuclease of the RNase II family. We have previously shown that Arabidopsis rnr1-null mutants exhibit specific abnormalities in the expression of the rRNA operon, including the accumulation of precursor 23S, 16S, and 4.5S species and a concomitant decrease in the mature species. 5S rRNA transcripts, however, accumulate to a very low level in both precursor and mature forms, suggesting that they are unstable in the rnr1 background. Here we demonstrate that rnr1 plants overaccumulate an antisense RNA, AS5, that is complementary to the 5S rRNA, its intergenic spacer, and the downstream trnR gene, which encodes tRNAArg, raising the possibility that AS5 destabilizes 5S rRNA or its precursor and/or blocks rRNA maturation. To investigate this, we used an in vitro system that supports 5S rRNA and trnR processing. We show that AS5 inhibits 5S rRNA maturation from a 5S-trnR precursor, and shorter versions of AS5 demonstrate that inhibition requires intergenic sequences. To test whether the sense and antisense RNAs form double-stranded regions in vitro, treatment with the single-strand-specific mung bean nuclease was used. These results suggest that 5S–AS5 duplexes interfere with a sense-strand secondary structure near the endonucleolytic cleavage site downstream from the 5S rRNA coding region. We hypothesize that these duplexes are degraded by a dsRNA-specific ribonuclease in vivo, contributing to the 5S rRNA deficiency observed in rnr1. PMID:21148395

  14. Secondary structural entropy in RNA switch (Riboswitch) identification.

    Science.gov (United States)

    Manzourolajdad, Amirhossein; Arnold, Jonathan

    2015-04-28

    RNA regulatory elements play a significant role in gene regulation. Riboswitches, a widespread group of regulatory RNAs, are vital components of many bacterial genomes. These regulatory elements generally function by forming a ligand-induced alternative fold that controls access to ribosome binding sites or other regulatory sites in RNA. Riboswitch-mediated mechanisms are ubiquitous across bacterial genomes. A typical class of riboswitch has its own unique structural and biological complexity, making de novo riboswitch identification a formidable task. Traditionally, riboswitches have been identified through comparative genomics based on sequence and structural homology. The limitations of structural-homology-based approaches, coupled with the assumption that there is a great diversity of undiscovered riboswitches, suggests the need for alternative methods for riboswitch identification, possibly based on features intrinsic to their structure. As of yet, no such reliable method has been proposed. We used structural entropy of riboswitch sequences as a measure of their secondary structural dynamics. Entropy values of a diverse set of riboswitches were compared to that of their mutants, their dinucleotide shuffles, and their reverse complement sequences under different stochastic context-free grammar folding models. Significance of our results was evaluated by comparison to other approaches, such as the base-pairing entropy and energy landscapes dynamics. Classifiers based on structural entropy optimized via sequence and structural features were devised as riboswitch identifiers and tested on Bacillus subtilis, Escherichia coli, and Synechococcus elongatus as an exploration of structural entropy based approaches. The unusually long untranslated region of the cotH in Bacillus subtilis, as well as upstream regions of certain genes, such as the sucC genes were associated with significant structural entropy values in genome-wide examinations. Various tests show that there

  15. FTIR protein secondary structure analysis of human ascending aortic tissues.

    Science.gov (United States)

    Bonnier, Franck; Rubin, Sylvain; Debelle, Laurent; Ventéo, Lydie; Pluot, Michel; Baehrel, Bernard; Manfait, Michel; Sockalingum, Ganesh D

    2008-08-01

    The advent of moderate dilatations in ascending aortas is often accompanied by structural modifications of the main components of the aortic tissue, elastin and collagen. In this study, we have undertaken an approach based on FTIR microscopy coupled to a curve-fitting procedure to analyze secondary structure modifications in these proteins in human normal and pathological aortic tissues. We found that the outcome of the aortic pathology is strongly influenced by these proteins, which are abundant in the media of the aortic wall, and that the advent of an aortic dilatation is generally accompanied by a decrease of parallel beta-sheet structures. Elastin, essentially composed of beta-sheet structures, seems to be directly related to these changes and therefore indicative of the elastic alteration of the aortic wall. Conventional microscopy and confocal fluorescence microscopy were used to compare FTIR microscopy results with the organization of the elastic fibers present in the tissues. This in-vitro study on 6 patients (three normal and three pathologic), suggests that such a spectroscopic marker, specific to aneurismal tissue characterization, could be important information for surgeons who face the dilemma of moderate aortic tissue dilatation of the ascending aortas.

  16. Rapid NMR screening of RNA secondary structure and binding

    Energy Technology Data Exchange (ETDEWEB)

    Helmling, Christina; Keyhani, Sara; Sochor, Florian; Fürtig, Boris; Hengesbach, Martin; Schwalbe, Harald, E-mail: schwalbe@nmr.uni-frankfurt.de [Johann Wolfgang Goethe-Universität, Institut für Organische Chemie und Chemische Biologie, Center for Biomolecular Magnetic Resonance (BMRZ) (Germany)

    2015-09-15

    Determination of RNA secondary structures by NMR spectroscopy is a useful tool e.g. to elucidate RNA folding space or functional aspects of regulatory RNA elements. However, current approaches of RNA synthesis and preparation are usually time-consuming and do not provide analysis with single nucleotide precision when applied for a large number of different RNA sequences. Here, we significantly improve the yield and 3′ end homogeneity of RNA preparation by in vitro transcription. Further, by establishing a native purification procedure with increased throughput, we provide a shortcut to study several RNA constructs simultaneously. We show that this approach yields μmol quantities of RNA with purities comparable to PAGE purification, while avoiding denaturation of the RNA.

  17. Eukaryote-specific rRNA expansion segments function in ribosome biogenesis.

    Science.gov (United States)

    Ramesh, Madhumitha; Woolford, John L

    2016-08-01

    The secondary structure of ribosomal RNA (rRNA) is largely conserved across all kingdoms of life. However, eukaryotes have evolved extra blocks of rRNA sequences, relative to those of prokaryotes, called expansion segments (ES). A thorough characterization of the potential roles of ES remains to be done, possibly because of limitations in the availability of robust systems to study rRNA mutants. We sought to systematically investigate the potential functions, if any, of the ES in 25S rRNA of Saccharomyces cerevisiae by deletion mutagenesis. We deleted 14 of the 16 different eukaryote-specific ES in yeast 25S rRNA individually and assayed their phenotypes. Our results show that all but two of the ES tested are necessary for optimal growth and are required for production of 25S rRNA, suggesting that ES play roles in ribosome biogenesis. Further, we classified expansion segments into groups that participate in early nucleolar, middle, and late nucleoplasmic steps of ribosome biogenesis, by assaying their pre-rRNA processing phenotypes. This study is the first of its kind to systematically identify the functions of eukaryote-specific expansion segments by showing that they play roles in specific steps of ribosome biogenesis. The catalog of phenotypes we identified, combined with previous investigations of the roles ribosomal proteins in large subunit biogenesis, leads us to infer that assembling ribosomes are composed of distinct RNA and protein structural neighborhood clusters that participate in specific steps of ribosome biogenesis. © 2016 Ramesh and Woolford; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  18. The predictive accuracy of secondary chemical shifts is more affected by protein secondary structure than solvent environment

    Energy Technology Data Exchange (ETDEWEB)

    Tremblay, Marie-Laurence; Banks, Aaron W.; Rainey, Jan K., E-mail: jan.rainey@dal.c [Dalhousie University, Department of Biochemistry and Molecular Biology (Canada)

    2010-04-15

    Biomolecular NMR spectroscopy frequently employs estimates of protein secondary structure using secondary chemical shift ({Delta}{delta}) values, measured as the difference between experimental and random coil chemical shifts (RCCS). Most published random coil data have been determined in aqueous conditions, reasonable for non-membrane proteins, but potentially less relevant for membrane proteins. Two new RCCS sets are presented here, determined in dimethyl sulfoxide (DMSO) and chloroform:methanol:water (4:4:1 by volume) at 298 K. A web-based program, CS-CHEMeleon, has been implemented to determine the accuracy of secondary structure assessment by calculating and comparing {Delta}{delta} values for various RCCS datasets. Using CS-CHEMeleon, {Delta}{delta} predicted versus experimentally determined secondary structures were compared for large datasets of membrane and non-membrane proteins as a function of RCCS dataset, {Delta}{delta} threshold, nucleus, localized parameter averaging and secondary structure type. Optimized {Delta}{delta} thresholds are presented both for published and for the DMSO and chloroform:methanol:water derived RCCS tables. Despite obvious RCCS variations between datasets, prediction of secondary structure was consistently similar. Strikingly, predictive accuracy seems to be most dependent upon the type of secondary structure, with helices being the most accurately predicted by {Delta}{delta} values using five different RCCS tables. We suggest caution when using {Delta}{delta}-based restraints in structure calculations as the underlying dataset may be biased. Comparative assessment of multiple RCCS datasets should be performed, and resulting {Delta}{delta}-based restraints weighted appropriately relative to other experimental restraints.

  19. LBA-ECO ND-04 Secondary Forest Recovery, Structure, and LAI, Central Amazonia, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set reports measurements of the canopy and structure of secondary forests regenerating from abandoned pastures. These secondary forests are located in the...

  20. Expected distance between terminal nucleotides of RNA secondary structures.

    Science.gov (United States)

    Clote, Peter; Ponty, Yann; Steyaert, Jean-Marc

    2012-09-01

    In "The ends of a large RNA molecule are necessarily close", Yoffe et al. (Nucleic Acids Res 39(1):292-299, 2011) used the programs RNAfold [resp. RNAsubopt] from Vienna RNA Package to calculate the distance between 5' and 3' ends of the minimum free energy secondary structure [resp. thermal equilibrium structures] of viral and random RNA sequences. Here, the 5'-3' distance is defined to be the length of the shortest path from 5' node to 3' node in the undirected graph, whose edge set consists of edges {i, i + 1} corresponding to covalent backbone bonds and of edges {i, j} corresponding to canonical base pairs. From repeated simulations and using a heuristic theoretical argument, Yoffe et al. conclude that the 5'-3' distance is less than a fixed constant, independent of RNA sequence length. In this paper, we provide a rigorous, mathematical framework to study the expected distance from 5' to 3' ends of an RNA sequence. We present recurrence relations that precisely define the expected distance from 5' to 3' ends of an RNA sequence, both for the Turner nearest neighbor energy model, as well as for a simple homopolymer model first defined by Stein and Waterman. We implement dynamic programming algorithms to compute (rather than approximate by repeated application of Vienna RNA Package) the expected distance between 5' and 3' ends of a given RNA sequence, with respect to the Turner energy model. Using methods of analytical combinatorics, that depend on complex analysis, we prove that the asymptotic expected 5'-3' distance of length n homopolymers is approximately equal to the constant 5.47211, while the asymptotic distance is 6.771096 if hairpins have a minimum of 3 unpaired bases and the probability that any two positions can form a base pair is 1/4. Finally, we analyze the 5'-3' distance for secondary structures from the STRAND database, and conclude that the 5'-3' distance is correlated with RNA sequence length.

  1. Amino Acid Molecular Units: Building Primary and Secondary Protein Structures

    Directory of Open Access Journals (Sweden)

    Aparecido R. Silva

    2008-05-01

    Full Text Available In order to guarantee the learning quality and suitable knowledge  use  about structural biology, it is fundamental to  exist, since the beginning of  students’ formation, the possibility of clear visualization of biomolecule structures. Nevertheless, the didactic books can only bring  schematic  drawings; even more elaborated figures and graphic computation  do not permit the necessary interaction.  The representation of three-dimensional molecular structures with ludic models, built with representative units, have supplied to the students and teachers a successfully experience to  visualize such structures and correlate them to the real molecules.  The design and applicability of the representative units were discussed with researchers and teachers before mould implementation.  In this stage  it  will be presented the  developed  kit  containing the  representative  plastic parts of the main amino acids.  The kit can demonstrate the interaction among the amino acids  functional groups  (represented by colors, shapes,  sizes and  the peptidic bonds between them  facilitating the assembly and visuali zation of the primary and secondary protein structure.  The models were designed for  Ca,  amino,  carboxyl groups  and  hydrogen. The  lateral chains have  well defined models that represent their geometrical shape.  The completed kit set  will be presented in this meeting (patent requested.  In the last phase of the project will be realized  an effective evaluation  of the kit  as a facilitative didactic tool of the teaching/learning process in the Structural Molecular Biology area.

  2. The 5S rRNA-histone repeat in the crustacean Artemia: structure, polymorphism and variation of the 5S rRNA segment in different populations.

    OpenAIRE

    Cruces, Jesús; Díaz-Guerra, Margarita; Gil, Inés; Renart, Jaime

    1989-01-01

    5S rRNA genes are linked to the histonc genes in the 13 populations of the crustacean Artemia that we have studied. In all cases, two types of repeat units arc found. Southern blot analysis of all populations shows that they can be grouped into three classes: a) American bisexuals; b) Eurasian bisexuals, and c) parthenogenetic organisms (all from Eurasia). Restriction analysis of a bisexual population from San Francisco Bay shows that the two repeat units are of 9.0 and 8.5 kb (with minor het...

  3. Evaluation of 16S rRNA gene primer pairs for monitoring microbial community structures showed high reproducibility within and low comparability between datasets generated with multiple archaeal and bacterial primer pairs

    Directory of Open Access Journals (Sweden)

    Martin Alexander Fischer

    2016-08-01

    Full Text Available The application of next-generation sequencing technology in microbial community analysis increased our knowledge and understanding of the complexity and diversity of a variety of ecosystems. In contrast to Bacteria, the archaeal domain was often not particularly addressed in the analysis of microbial communities. Consequently, established primers specifically amplifying the archaeal 16S ribosomal gene region are scarce compared to the variety of primers targeting bacterial sequences. In this study, we aimed to validate archaeal primers suitable for high throughput next generation sequencing. Three archaeal 16S primer pairs as well as two bacterial and one general microbial 16S primer pairs were comprehensively tested by in-silico evaluation and performing an experimental analysis of a complex microbial community of a biogas reactor. The results obtained clearly demonstrate that comparability of community profiles established using different primer pairs is difficult. 16S rRNA gene data derived from a shotgun metagenome of the same reactor sample added an additional perspective on the community structure. Furthermore, in-silico evaluation of primers, especially those for amplification of archaeal 16S rRNA gene regions, does not necessarily reflect the results obtained in experimental approaches. In the latter, archaeal primer pair ArchV34 showed the highest similarity to the archaeal community structure compared to observed by the metagenomic approach and thus appears to be the appropriate for analyzing archaeal communities in biogas reactors. However, a disadvantage of this primer pair was its low specificity for the archaeal domain in the experimental application leading to high amounts of bacterial sequences within the dataset. Overall our results indicate a rather limited comparability between community structures investigated and determined using different primer pairs as well as between metagenome and 16S rRNA gene amplicon based community

  4. Metschnikowia Species Share a Pool of Diverse rRNA Genes Differing in Regions That Determine Hairpin-Loop Structures and Evolve by Reticulation.

    Directory of Open Access Journals (Sweden)

    Matthias Sipiczki

    Full Text Available Modern taxonomy of yeasts is mainly based on phylogenetic analysis of conserved DNA and protein sequences. By far the most frequently used sequences are those of the repeats of the chromosomal rDNA array. It is generally accepted that the rDNA repeats of a genome have identical sequences due to the phenomenon of sequence homogenisation and can thus be used for identification and barcoding of species. Here we show that the rDNA arrays of the type strains of Metschnikowia andauensis and M. fructicola are not homogenised. Both have arrays consisting of diverse repeats that differ from each other in the D1/D2 domains by up to 18 and 25 substitutions. The variable sites are concentrated in two regions that correspond to back-folding stretches of hairpin loops in the predicted secondary structure of the RNA molecules. The substitutions do not alter significantly the overall hairpin-loop structure due to wobble base pairing at sites of C-T transitions and compensatory mutations in the complementary strand of the hairpin stem. The phylogenetic and network analyses of the cloned sequences revealed that the repeats had not evolved in a vertical tree-like way but reticulation might have shaped the rDNA arrays of both strains. The neighbour-net analysis of all cloned sequences of the type strains and the database sequences of different strains further showed that these species share a continuous pool of diverse repeats that appear to evolve by reticulate evolution.

  5. Floristic and structural changes in secondary forests following ...

    African Journals Online (AJOL)

    The results showed that the forests were less diversified with few species very common in the forest stands; the most dominant were Lonchocarpus sericeus and Anogeissus leiocarpa in the secondary forests, and Dialium guineense, Diospyros mespiliformis and Afzelia africana in the old-growth forests. The secondary ...

  6. Characterization of a Novel Association between Two Trypanosome-Specific Proteins and 5S rRNA

    Science.gov (United States)

    Ciganda, Martin; Williams, Noreen

    2012-01-01

    P34 and P37 are two previously identified RNA binding proteins in the flagellate protozoan Trypanosoma brucei. RNA interference studies have determined that the proteins are essential and are involved in ribosome biogenesis. Here, we show that these proteins interact in vitro with the 5S rRNA with nearly identical binding characteristics in the absence of other cellular factors. The T. brucei 5S rRNA has a complex secondary structure and presents four accessible loops (A to D) for interactions with RNA-binding proteins. In other eukaryotes, loop C is bound by the L5 ribosomal protein and loop A mainly by TFIIIA. The binding of P34 and P37 to T. brucei 5S rRNA involves the LoopA region of the RNA, but these proteins also protect the L5 binding site located on LoopC. PMID:22253864

  7. Energy profile and secondary structure impact shRNA efficacy

    Directory of Open Access Journals (Sweden)

    Zeng Xiao

    2009-07-01

    Full Text Available Abstract Background RNA interference (RNAi is a cellular mechanism in which a short/small double stranded RNA induces the degradation of its sequence specific target mRNA, leading to specific gene silencing. Since its discovery, RNAi has become a powerful biological technique for gene function studies and drug discovery. The very first requirement of applying RNAi is to design functional small interfering RNA (siRNA that can uniquely induce the degradation of the targeted mRNA. It has been shown that many functional synthetic siRNAs share some common characteristics, such as GC content limitation and free energy preferences at both terminals, etc. Results Our three-phase algorithm was developed to design siRNA on a whole-genome scale based on those identified characteristics of functional siRNA. When this algorithm was applied to design short hairpin RNA (shRNA, the validated success rate of shRNAs was over 70%, which was almost double the rate reported for TRC library. This indicates that the designs of siRNA and shRNA may share the same concerns. Further analysis of the shRNA dataset of 444 designs reveals that the high free energy states of the two terminals have the largest positive impact on the shRNA efficacy. Enforcing these energy characteristics of both terminals can further improve the shRNA design success rate to 83.1%. We also found that functional shRNAs have less probability for their 3' terminals to be involved in mRNA secondary structure formation. Conclusion Functional shRNAs prefer high free energy states at both terminals. High free energy states of the two terminals were found to be the largest positive impact factor on shRNA efficacy. In addition, the accessibility of the 3' terminal is another key factor to shRNA efficacy.

  8. Distributions of amino acids suggest that certain residue types more effectively determine protein secondary structure.

    Science.gov (United States)

    Saraswathi, S; Fernández-Martínez, J L; Koliński, A; Jernigan, R L; Kloczkowski, A

    2013-10-01

    Exponential growth in the number of available protein sequences is unmatched by the slower growth in the number of structures. As a result, the development of efficient and fast protein secondary structure prediction methods is essential for the broad comprehension of protein structures. Computational methods that can efficiently determine secondary structure can in turn facilitate protein tertiary structure prediction, since most methods rely initially on secondary structure predictions. Recently, we have developed a fast learning optimized prediction methodology (FLOPRED) for predicting protein secondary structure (Saraswathi et al. in JMM 18:4275, 2012). Data are generated by using knowledge-based potentials combined with structure information from the CATH database. A neural network-based extreme learning machine (ELM) and advanced particle swarm optimization (PSO) are used with this data to obtain better and faster convergence to more accurate secondary structure predicted results. A five-fold cross-validated testing accuracy of 83.8 % and a segment overlap (SOV) score of 78.3 % are obtained in this study. Secondary structure predictions and their accuracy are usually presented for three secondary structure elements: α-helix, β-strand and coil but rarely have the results been analyzed with respect to their constituent amino acids. In this paper, we use the results obtained with FLOPRED to provide detailed behaviors for different amino acid types in the secondary structure prediction. We investigate the influence of the composition, physico-chemical properties and position specific occurrence preferences of amino acids within secondary structure elements. In addition, we identify the correlation between these properties and prediction accuracy. The present detailed results suggest several important ways that secondary structure predictions can be improved in the future that might lead to improved protein design and engineering.

  9. JNSViewer-A JavaScript-based Nucleotide Sequence Viewer for DNA/RNA secondary structures.

    Science.gov (United States)

    Shi, Jieming; Li, Xi; Dong, Min; Graham, Mitchell; Yadav, Nehul; Liang, Chun

    2017-01-01

    Many tools are available for visualizing RNA or DNA secondary structures, but there is scarce implementation in JavaScript that provides seamless integration with the increasingly popular web computational platforms. We have developed JNSViewer, a highly interactive web service, which is bundled with several popular tools for DNA/RNA secondary structure prediction and can provide precise and interactive correspondence among nucleotides, dot-bracket data, secondary structure graphs, and genic annotations. In JNSViewer, users can perform RNA secondary structure predictions with different programs and settings, add customized genic annotations in GFF format to structure graphs, search for specific linear motifs, and extract relevant structure graphs of sub-sequences. JNSViewer also allows users to choose a transcript or specific segment of Arabidopsis thaliana genome sequences and predict the corresponding secondary structure. Popular genome browsers (i.e., JBrowse and BrowserGenome) were integrated into JNSViewer to provide powerful visualizations of chromosomal locations, genic annotations, and secondary structures. In addition, we used StructureFold with default settings to predict some RNA structures for Arabidopsis by incorporating in vivo high-throughput RNA structure profiling data and stored the results in our web server, which might be a useful resource for RNA secondary structure studies in plants. JNSViewer is available at http://bioinfolab.miamioh.edu/jnsviewer/index.html.

  10. JNSViewer-A JavaScript-based Nucleotide Sequence Viewer for DNA/RNA secondary structures.

    Directory of Open Access Journals (Sweden)

    Jieming Shi

    Full Text Available Many tools are available for visualizing RNA or DNA secondary structures, but there is scarce implementation in JavaScript that provides seamless integration with the increasingly popular web computational platforms. We have developed JNSViewer, a highly interactive web service, which is bundled with several popular tools for DNA/RNA secondary structure prediction and can provide precise and interactive correspondence among nucleotides, dot-bracket data, secondary structure graphs, and genic annotations. In JNSViewer, users can perform RNA secondary structure predictions with different programs and settings, add customized genic annotations in GFF format to structure graphs, search for specific linear motifs, and extract relevant structure graphs of sub-sequences. JNSViewer also allows users to choose a transcript or specific segment of Arabidopsis thaliana genome sequences and predict the corresponding secondary structure. Popular genome browsers (i.e., JBrowse and BrowserGenome were integrated into JNSViewer to provide powerful visualizations of chromosomal locations, genic annotations, and secondary structures. In addition, we used StructureFold with default settings to predict some RNA structures for Arabidopsis by incorporating in vivo high-throughput RNA structure profiling data and stored the results in our web server, which might be a useful resource for RNA secondary structure studies in plants. JNSViewer is available at http://bioinfolab.miamioh.edu/jnsviewer/index.html.

  11. JNSViewer—A JavaScript-based Nucleotide Sequence Viewer for DNA/RNA secondary structures

    Science.gov (United States)

    Dong, Min; Graham, Mitchell; Yadav, Nehul

    2017-01-01

    Many tools are available for visualizing RNA or DNA secondary structures, but there is scarce implementation in JavaScript that provides seamless integration with the increasingly popular web computational platforms. We have developed JNSViewer, a highly interactive web service, which is bundled with several popular tools for DNA/RNA secondary structure prediction and can provide precise and interactive correspondence among nucleotides, dot-bracket data, secondary structure graphs, and genic annotations. In JNSViewer, users can perform RNA secondary structure predictions with different programs and settings, add customized genic annotations in GFF format to structure graphs, search for specific linear motifs, and extract relevant structure graphs of sub-sequences. JNSViewer also allows users to choose a transcript or specific segment of Arabidopsis thaliana genome sequences and predict the corresponding secondary structure. Popular genome browsers (i.e., JBrowse and BrowserGenome) were integrated into JNSViewer to provide powerful visualizations of chromosomal locations, genic annotations, and secondary structures. In addition, we used StructureFold with default settings to predict some RNA structures for Arabidopsis by incorporating in vivo high-throughput RNA structure profiling data and stored the results in our web server, which might be a useful resource for RNA secondary structure studies in plants. JNSViewer is available at http://bioinfolab.miamioh.edu/jnsviewer/index.html. PMID:28582416

  12. Secondary Impacts on Structures on the Lunar Surface

    Science.gov (United States)

    Christiansen, Eric; Walker, James D.; Grosch, Donald J.

    2010-01-01

    The Altair Lunar Lander is being designed for the planned return to the Moon by 2020. Since it is hoped that lander components will be re-used by later missions, studies are underway to examine the exposure threat to the lander sitting on the Lunar surface for extended periods. These threats involve both direct strikes of meteoroids on the vehicle as well as strikes from Lunar regolith and rock thrown by nearby meteorite strikes. Currently, the lander design is comprised of up to 10 different types of pressure vessels. These vessels included the manned habitation module, fuel, cryogenic fuel and gas storage containers, and instrument bays. These pressure vessels have various wall designs, including various aluminum alloys, honeycomb, and carbon-fiber composite materials. For some of the vessels, shielding is being considered. This program involved the test and analysis of six pressure vessel designs, one of which included a Whipple bumper shield. In addition to the pressure vessel walls, all the pressure vessels are wrapped in multi-layer insulation (MLI). Two variants were tested without the MLI to better understand the role of the MLI in the impact performance. The tests of performed were to examine the secondary impacts on these structures as they rested on the Lunar surface. If a hypervelocity meteor were to strike the surface nearby, it would throw regolith and rock debris into the structure at a much lower velocity. Also, when the manned module departs for the return to Earth, its rocket engines throw up debris that can impact the remaining lander components and cause damage. Glass spheres were used as a stimulant for the regolith material. Impact tests were performed with a gas gun to find the V50 of various sized spheres striking the pressure vessels. The impacts were then modeled and a fast-running approximate model for the V50 data was developed. This model was for performing risk analysis to assist in the vessel design and in the identification of ideal

  13. Does lack of secondary structure imply intrinsic disorder in proteins? A sequence analysis.

    Science.gov (United States)

    Rani, Pooja; Baruah, Anupaul; Biswas, Parbati

    2014-10-01

    Intrinsically disordered proteins (IDPs)/protein regions (IDPRs) lack unique three-dimensional structure at the level of secondary and/or tertiary structure and are represented as an ensemble of interchanging conformations. To investigate the role of presence/absence of secondary structures in promoting intrinsic disorder in proteins, a comparative sequence analysis of IDPs, IDPRs and proteins with minimal secondary structures (less than 5%) is required. A sequence analysis reveals proteins with minimal secondary structure content have high mean net positive charge, low mean net hydrophobicity and low sequence complexity. Interestingly, analysis of the relative local electrostatic interactions reveal that an increase in the relative repulsive interactions between amino acids separated by three or four residues lead to either loss of secondary structure or intrinsic disorder. IDPRs show increase in both local negative-negative and positive-positive repulsive interactions. While IDPs show a marked increase in the local negative-negative interactions, proteins with minimal secondary structure depict an increase in the local positive-positive interactions. IDPs and IDPRs are enriched in D, E and Q residues, while proteins with minimal secondary structure are depleted of these residues. Proteins with minimal secondary structures have higher content of G and C, while IDPs and IDPRs are depleted of these residues. These results confirm that proteins with minimal secondary structure have a distinctly different propensity for charge, hydrophobicity, specific amino acids and local electrostatic interactions as compared to IDPs/IDPRs. Thus we conclude that lack of secondary structure may be a necessary but not a sufficient condition for intrinsic disorder in proteins. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Structural Basis for the Methylation of G1405 in 16S rRNA by Aminoglycoside Resistance Methyltransferase Sgm from an Antibiotic Producer: a Diversity of Active Sites in m7G Methyltransferases

    Energy Technology Data Exchange (ETDEWEB)

    Husain, N.; Tkaczuk, K; Tulsidas, S; Kaminska, K; Cubrilo, S; Maravic -Vlahovicek, G; Bujnicki, J; Sivaraman, J

    2010-01-01

    Sgm (Sisomicin-gentamicin methyltransferase) from antibiotic-producing bacterium Micromonospora zionensis is an enzyme that confers resistance to aminoglycosides like gentamicin and sisomicin by specifically methylating G1405 in bacterial 16S rRNA. Sgm belongs to the aminoglycoside resistance methyltransferase (Arm) family of enzymes that have been recently found to spread by horizontal gene transfer among disease-causing bacteria. Structural characterization of Arm enzymes is the key to understand their mechanism of action and to develop inhibitors that would block their activity. Here we report the structure of Sgm in complex with cofactors S-adenosylmethionine (AdoMet) and S-adenosylhomocysteine (AdoHcy) at 2.0 and 2.1 {angstrom} resolution, respectively, and results of mutagenesis and rRNA footprinting, and protein-substrate docking. We propose the mechanism of methylation of G1405 by Sgm and compare it with other m{sup 7}G methyltransferases, revealing a surprising diversity of active sites and binding modes for the same basic reaction of RNA modification. This analysis can serve as a stepping stone towards developing drugs that would specifically block the activity of Arm methyltransferases and thereby re-sensitize pathogenic bacteria to aminoglycoside antibiotics.

  15. Structure of the bifunctional methyltransferase YcbY (RlmKL) that adds the m7G2069 and m2G2445 modifications in Escherichia coli 23S rRNA

    DEFF Research Database (Denmark)

    Wang, Kai-Tuo; Desmolaize, Benoit; Nan, Jie

    2012-01-01

    The 23S rRNA nucleotide m(2)G2445 is highly conserved in bacteria, and in Escherichia coli this modification is added by the enzyme YcbY. With lengths of around 700 amino acids, YcbY orthologs are the largest rRNA methyltransferases identified in Gram-negative bacteria, and they appear...... to be fusions from two separate proteins found in Gram-positives. The crystal structures described here show that both the N- and C-terminal halves of E. coli YcbY have a methyltransferase active site and their folding patterns respectively resemble the Streptococcus mutans proteins Smu472 and Smu776. Mass......, and this nucleotide remains unmodified in Gram-positive rRNAs. The E.coli YcbY enzyme is the first example of a methyltransferase catalyzing two mechanistically different types of RNA modification, and has been renamed as the Ribosomal large subunit methyltransferase, RlmKL. Our structural and functional data provide...

  16. Eukaryotic 5S rRNA biogenesis

    Science.gov (United States)

    Ciganda, Martin; Williams, Noreen

    2012-01-01

    The ribosome is a large complex containing both protein and RNA which must be assembled in a precise manner to allow proper functioning in the critical role of protein synthesis. 5S rRNA is the smallest of the RNA components of the ribosome, and although it has been studied for decades, we still do not have a clear understanding of its function within the complex ribosome machine. It is the only RNA species that binds ribosomal proteins prior to its assembly into the ribosome. Its transport into the nucleolus requires this interaction. Here we present an overview of some of the key findings concerning the structure and function of 5S rRNA and how its association with specific proteins impacts its localization and function. PMID:21957041

  17. A comparative method for finding and folding RNA secondary structures within protein-coding regions

    DEFF Research Database (Denmark)

    Pedersen, Jakob Skou; Meyer, Irmtraud Margret; Forsberg, Roald

    2004-01-01

    Existing computational methods for RNA secondary-structure prediction tacitly assume RNA to only encode functional RNA structures. However, experimental studies have revealed that some RNA sequences, e.g. compact viral genomes, can simultaneously encode functional RNA structures as well as proteins...... that RNA-DECODER's parameters can be automatically trained to successfully fold known secondary structures within the HCV genome. We scan the genomes of HCV and polio virus for conserved secondary-structure elements, and analyze performance as a function of available evolutionary information. On known...... secondary structures, RNA-DECODER shows a sensitivity similar to the programs MFOLD, PFOLD and RNAALIFOLD. When scanning the entire genomes of HCV and polio virus for structure elements, RNA-DECODER's results indicate a markedly higher specificity than MFOLD, PFOLD and RNAALIFOLD....

  18. Mathematical and Biological Modelling of RNA Secondary Structure and Its Effects on Gene Expression

    Directory of Open Access Journals (Sweden)

    T. A. Hughes

    2006-01-01

    Full Text Available Secondary structures within the 5′ untranslated regions of messenger RNAs can have profound effects on the efficiency of translation of their messages and thereby on gene expression. Consequently they can act as important regulatory motifs in both physiological and pathological settings. Current approaches to predicting the secondary structure of these RNA sequences find the structure with the global-minimum free energy. However, since RNA folds progressively from the 5′ end when synthesised or released from the translational machinery, this may not be the most probable structure. We discuss secondary structure prediction based on local-minimisation of free energy with thermodynamic fluctuations as nucleotides are added to the 3′ end and show that these can result in different secondary structures. We also discuss approaches for studying the extent of the translational inhibition specified by structures within the 5′ untranslated region.

  19. Original Paper Floristic and structural changes in secondary forests ...

    African Journals Online (AJOL)

    dense semi-deciduous fragments, 296 ha of. Tectona grandis L.f. and Gmelina arborea. Roxb. plantations, and the remaining surface include secondary forests and fallows. (ONAB, 2011). Some areas were enriched with Khaya senegalensis (Desr.) A.Juss.,. Khaya grandifolia C.DC., Holoptelea grandis. (Hutch.) Mildbr.

  20. Deciphering the shape and deformation of secondary structures through local conformation analysis

    Directory of Open Access Journals (Sweden)

    Camproux Anne-Claude

    2011-02-01

    Full Text Available Abstract Background Protein deformation has been extensively analysed through global methods based on RMSD, torsion angles and Principal Components Analysis calculations. Here we use a local approach, able to distinguish among the different backbone conformations within loops, α-helices and β-strands, to address the question of secondary structures' shape variation within proteins and deformation at interface upon complexation. Results Using a structural alphabet, we translated the 3 D structures of large sets of protein-protein complexes into sequences of structural letters. The shape of the secondary structures can be assessed by the structural letters that modeled them in the structural sequences. The distribution analysis of the structural letters in the three protein compartments (surface, core and interface reveals that secondary structures tend to adopt preferential conformations that differ among the compartments. The local description of secondary structures highlights that curved conformations are preferred on the surface while straight ones are preferred in the core. Interfaces display a mixture of local conformations either preferred in core or surface. The analysis of the structural letters transition occurring between protein-bound and unbound conformations shows that the deformation of secondary structure is tightly linked to the compartment preference of the local conformations. Conclusion The conformation of secondary structures can be further analysed and detailed thanks to a structural alphabet which allows a better description of protein surface, core and interface in terms of secondary structures' shape and deformation. Induced-fit modification tendencies described here should be valuable information to identify and characterize regions under strong structural constraints for functional reasons.

  1. R-CHIE: a web server and R package for visualizing RNA secondary structures.

    Science.gov (United States)

    Lai, Daniel; Proctor, Jeff R; Zhu, Jing Yun A; Meyer, Irmtraud M

    2012-07-01

    Visually examining RNA structures can greatly aid in understanding their potential functional roles and in evaluating the performance of structure prediction algorithms. As many functional roles of RNA structures can already be studied given the secondary structure of the RNA, various methods have been devised for visualizing RNA secondary structures. Most of these methods depict a given RNA secondary structure as a planar graph consisting of base-paired stems interconnected by roundish loops. In this article, we present an alternative method of depicting RNA secondary structure as arc diagrams. This is well suited for structures that are difficult or impossible to represent as planar stem-loop diagrams. Arc diagrams can intuitively display pseudo-knotted structures, as well as transient and alternative structural features. In addition, they facilitate the comparison of known and predicted RNA secondary structures. An added benefit is that structure information can be displayed in conjunction with a corresponding multiple sequence alignments, thereby highlighting structure and primary sequence conservation and variation. We have implemented the visualization algorithm as a web server R-chie as well as a corresponding R package called R4RNA, which allows users to run the software locally and across a range of common operating systems.

  2. How Mg(2+) ion and water network affect the stability and structure of non-Watson-Crick base pairs in E. coli loop E of 5S rRNA: a molecular dynamics and reference interaction site model (RISM) study.

    Science.gov (United States)

    Shanker, Sudhanshu; Bandyopadhyay, Pradipta

    2017-08-01

    The non-Watson-Crick (non-WC) base pairs of Escherichia coli loop E of 5S rRNA are stabilized by Mg(2+) ions through water-mediated interaction. It is important to know the synergic role of Mg(2+) and the water network surrounding Mg(2+) in stabilizing the non-WC base pairs of RNA. For this purpose, free energy change of the system is calculated using molecular dynamics (MD) simulation as Mg(2+) is pulled from RNA, which causes disturbance of the water network. It was found that Mg(2+) remains hexahydrated unless it is close to or far from RNA. In the pentahydrated form, Mg(2+) interacts directly with RNA. Water network has been identified by two complimentary methods; MD followed by a density-based clustering algorithm and three-dimensional-reference interaction site model. These two methods gave similar results. Identification of water network around Mg(2+) and non-WC base pairs gives a clue to the strong effect of water network on the stability of this RNA. Based on sequence analysis of all Eubacteria 5s rRNA, we propose that hexahydrated Mg(2+) is an integral part of this RNA and geometry of base pairs surrounding it adjust to accommodate the [Formula: see text]. Overall the findings from this work can help in understanding the basis of the complex structure and stability of RNA with non-WC base pairs.

  3. Protein secondary structure assignment revisited: a detailed analysis of different assignment methods

    Directory of Open Access Journals (Sweden)

    de Brevern Alexandre G

    2005-09-01

    Full Text Available Abstract Background A number of methods are now available to perform automatic assignment of periodic secondary structures from atomic coordinates, based on different characteristics of the secondary structures. In general these methods exhibit a broad consensus as to the location of most helix and strand core segments in protein structures. However the termini of the segments are often ill-defined and it is difficult to decide unambiguously which residues at the edge of the segments have to be included. In addition, there is a "twilight zone" where secondary structure segments depart significantly from the idealized models of Pauling and Corey. For these segments, one has to decide whether the observed structural variations are merely distorsions or whether they constitute a break in the secondary structure. Methods To address these problems, we have developed a method for secondary structure assignment, called KAKSI. Assignments made by KAKSI are compared with assignments given by DSSP, STRIDE, XTLSSTR, PSEA and SECSTR, as well as secondary structures found in PDB files, on 4 datasets (X-ray structures with different resolution range, NMR structures. Results A detailed comparison of KAKSI assignments with those of STRIDE and PSEA reveals that KAKSI assigns slightly longer helices and strands than STRIDE in case of one-to-one correspondence between the segments. However, KAKSI tends also to favor the assignment of several short helices when STRIDE and PSEA assign longer, kinked, helices. Helices assigned by KAKSI have geometrical characteristics close to those described in the PDB. They are more linear than helices assigned by other methods. The same tendency to split long segments is observed for strands, although less systematically. We present a number of cases of secondary structure assignments that illustrate this behavior. Conclusion Our method provides valuable assignments which favor the regularity of secondary structure segments.

  4. Accurate prediction of protein secondary structure and solvent accessibility by consensus combiners of sequence and structure information

    Directory of Open Access Journals (Sweden)

    Vullo Alessandro

    2007-06-01

    Full Text Available Abstract Background Structural properties of proteins such as secondary structure and solvent accessibility contribute to three-dimensional structure prediction, not only in the ab initio case but also when homology information to known structures is available. Structural properties are also routinely used in protein analysis even when homology is available, largely because homology modelling is lower throughput than, say, secondary structure prediction. Nonetheless, predictors of secondary structure and solvent accessibility are virtually always ab initio. Results Here we develop high-throughput machine learning systems for the prediction of protein secondary structure and solvent accessibility that exploit homology to proteins of known structure, where available, in the form of simple structural frequency profiles extracted from sets of PDB templates. We compare these systems to their state-of-the-art ab initio counterparts, and with a number of baselines in which secondary structures and solvent accessibilities are extracted directly from the templates. We show that structural information from templates greatly improves secondary structure and solvent accessibility prediction quality, and that, on average, the systems significantly enrich the information contained in the templates. For sequence similarity exceeding 30%, secondary structure prediction quality is approximately 90%, close to its theoretical maximum, and 2-class solvent accessibility roughly 85%. Gains are robust with respect to template selection noise, and significant for marginal sequence similarity and for short alignments, supporting the claim that these improved predictions may prove beneficial beyond the case in which clear homology is available. Conclusion The predictive system are publicly available at the address http://distill.ucd.ie.

  5. Non-B DNA Secondary Structures and Their Resolution by RecQ Helicases

    Directory of Open Access Journals (Sweden)

    Sudha Sharma

    2011-01-01

    Full Text Available In addition to the canonical B-form structure first described by Watson and Crick, DNA can adopt a number of alternative structures. These non-B-form DNA secondary structures form spontaneously on tracts of repeat sequences that are abundant in genomes. In addition, structured forms of DNA with intrastrand pairing may arise on single-stranded DNA produced transiently during various cellular processes. Such secondary structures have a range of biological functions but also induce genetic instability. Increasing evidence suggests that genomic instabilities induced by non-B DNA secondary structures result in predisposition to diseases. Secondary DNA structures also represent a new class of molecular targets for DNA-interactive compounds that might be useful for targeting telomeres and transcriptional control. The equilibrium between the duplex DNA and formation of multistranded non-B-form structures is partly dependent upon the helicases that unwind (resolve these alternate DNA structures. With special focus on tetraplex, triplex, and cruciform, this paper summarizes the incidence of non-B DNA structures and their association with genomic instability and emphasizes the roles of RecQ-like DNA helicases in genome maintenance by resolution of DNA secondary structures. In future, RecQ helicases are anticipated to be additional molecular targets for cancer chemotherapeutics.

  6. The tension between organisational sub-structures in secondary schools and educational reform

    NARCIS (Netherlands)

    Imants, J.G.M.; Sleegers, P.J.C.; Witziers, B.

    2001-01-01

    In Dutch secondary schools the recent trend has been to replace the two existing sub-structures of subject departments and student guidance units by one system of integrated and decentralised teams. The aim of this article is to gain more insight into how secondary schools can provide supportive

  7. Testing Mediation Using Multiple Regression and Structural Equation Modeling Analyses in Secondary Data

    Science.gov (United States)

    Li, Spencer D.

    2011-01-01

    Mediation analysis in child and adolescent development research is possible using large secondary data sets. This article provides an overview of two statistical methods commonly used to test mediated effects in secondary analysis: multiple regression and structural equation modeling (SEM). Two empirical studies are presented to illustrate the…

  8. Secondary collisions and injury severity: A joint analysis using structural equation models.

    Science.gov (United States)

    Xie, Kun; Ozbay, Kaan; Yang, Hong

    2017-10-23

    This study aims to investigate the contributing factors to secondary collisions and the effects of secondary collisions on injury severity levels. Manhattan, which is the most densely populated urban area of New York City, is used as a case study. In Manhattan, about 7.5% of crash events become involved with secondary collisions and as high as 9.3% of those secondary collisions lead to incapacitating and fatal injuries. Structural equation models (SEMs) are proposed to jointly model the presence of secondary collisions and injury severity levels and adjust for the endogeneity effects. The structural relationship among secondary collisions, injury severity, and contributing factors such as speeding, alcohol, fatigue, brake defects, limited view, and rain are fully explored using SEMs. In addition, to assess the temporal effects, we use time as a moderator in the proposed SEM framework. Due to its better performance compared with other models, the SEM with no constraint is used to investigate the contributing factors to secondary collisions. Thirteen explanatory variables are found to contribute to the presence of secondary collisions, including alcohol, drugs, inattention, inexperience, sleep, control disregarded, speeding, fatigue, defective brakes, pedestrian involved, defective pavement, limited view, and rain. Regarding the temporal effects, results indicate that it is more likely to sustain secondary collisions and severe injuries at night. This study fully investigates the contributing factors to secondary collisions and estimates the safety effects of secondary collisions after adjusting for the endogeneity effects and shows the advantage of using SEMs in exploring the structural relationship between risk factors and safety indicators. Understanding the causes and impacts of secondary collisions can help transportation agencies and automobile manufacturers develop effective injury prevention countermeasures.

  9. RNAVLab: A virtual laboratory for studying RNA secondary structures based on grid computing technology.

    Science.gov (United States)

    Taufer, Michela; Leung, Ming-Ying; Solorio, Thamar; Licon, Abel; Mireles, David; Araiza, Roberto; Johnson, Kyle L

    2008-11-01

    As ribonucleic acid (RNA) molecules play important roles in many biological processes including gene expression and regulation, their secondary structures have been the focus of many recent studies. Despite the computing power of supercomputers, computationally predicting secondary structures with thermodynamic methods is still not feasible when the RNA molecules have long nucleotide sequences and include complex motifs such as pseudoknots. This paper presents RNAVLab (RNA Virtual Laboratory), a virtual laboratory for studying RNA secondary structures including pseudoknots that allows scientists to address this challenge. Two important case studies show the versatility and functionalities of RNAVLab. The first study quantifies its capability to rebuild longer secondary structures from motifs found in systematically sampled nucleotide segments. The extensive sampling and predictions are made feasible in a short turnaround time because of the grid technology used. The second study shows how RNAVLab allows scientists to study the viral RNA genome replication mechanisms used by members of the virus family Nodaviridae.

  10. Secondary systems modeled as fuzzy sub-structures

    DEFF Research Database (Denmark)

    Tarp-Johansen, Niels Jacob; Ditlevsen, Ove Dalager; Lin, Y.K.

    1998-01-01

    are considered for a rigid one-degree of freedom master structure. Approximate distribution properties of the impedance, the frequency response function and other related functions of the imposed frequency are obtained by use of Winterstein approximation technique. This information can be used to determine...... in the simplest case be modeled by attaching random single degree of freedom oscillators, called fuzzies, to the master structure at randomly distributed points of the structure. Each of these fuzzies are characterized by a random triplet of mass, eigenfrequency, and damping ratio. This characterization can...

  11. Large deviations for random trees and the branching of RNA secondary structures.

    Science.gov (United States)

    Bakhtin, Yuri; Heitsch, Christine E

    2009-01-01

    We give a Large Deviation Principle (LDP) with explicit rate function for the distribution of vertex degrees in plane trees, a combinatorial model of RNA secondary structures. We calculate the typical degree distributions based on nearest neighbor free energies, and compare our results with the branching configurations found in two sets of large RNA secondary structures. We find substantial agreement overall, with some interesting deviations which merit further study.

  12. Inflatable Habitat with Integrated Primary and Secondary Structure Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Paragon Space Development Corp (Paragon) and Thin Red Line Aerospace (TRLA) proposes to explore the utilization of inflatable structures by designing a habitation...

  13. A new sequence data set of SSU rRNA gene for Scleractinia and its phylogenetic and ecological applications

    KAUST Repository

    Arrigoni, Roberto

    2016-11-27

    Scleractinian corals (i.e. hard corals) play a fundamental role in building and maintaining coral reefs, one of the most diverse ecosystems on Earth. Nevertheless, their phylogenies remain largely unresolved and little is known about dispersal and survival of their planktonic larval phase. The small subunit ribosomal RNA (SSU rRNA) is a commonly used gene for DNA barcoding in several metazoans, and small variable regions of SSU rRNA are widely adopted as barcode marker to investigate marine plankton community structure worldwide. Here, we provide a large sequence data set of the complete SSU rRNA gene from 298 specimens, representing all known extant reef coral families and a total of 106 genera. The secondary structure was extremely conserved within the order with few exceptions due to insertions or deletions occurring in the variable regions. Remarkable differences in SSU rRNA length and base composition were detected between and within acroporids (Acropora, Montipora, Isopora and Alveopora) compared to other corals. The V4 and V9 regions seem to be promising barcode loci because variation at commonly used barcode primer binding sites was extremely low, while their levels of divergence allowed families and genera to be distinguished. A time-calibrated phylogeny of Scleractinia is provided, and mutation rate heterogeneity is demonstrated across main lineages. The use of this data set as a valuable reference for investigating aspects of ecology, biology, molecular taxonomy and evolution of scleractinian corals is discussed.

  14. Covalent bond symmetry breaking and protein secondary structure

    OpenAIRE

    Lundgren, Martin; Niemi, Antti J.

    2011-01-01

    Both symmetry and organized breaking of symmetry have a pivotal r\\^ole in our understanding of structure and pattern formation in physical systems, including the origin of mass in the Universe and the chiral structure of biological macromolecules. Here we report on a new symmetry breaking phenomenon that takes place in all biologically active proteins, thus this symmetry breaking relates to the inception of life. The unbroken symmetry determines the covalent bond geometry of a sp3 hybridized ...

  15. Protein Structure Determination by Assembling Super-Secondary Structure Motifs Using Pseudocontact Shifts.

    Science.gov (United States)

    Pilla, Kala Bharath; Otting, Gottfried; Huber, Thomas

    2017-03-07

    Computational and nuclear magnetic resonance hybrid approaches provide efficient tools for 3D structure determination of small proteins, but currently available algorithms struggle to perform with larger proteins. Here we demonstrate a new computational algorithm that assembles the 3D structure of a protein from its constituent super-secondary structural motifs (Smotifs) with the help of pseudocontact shift (PCS) restraints for backbone amide protons, where the PCSs are produced from different metal centers. The algorithm, DINGO-PCS (3D assembly of Individual Smotifs to Near-native Geometry as Orchestrated by PCSs), employs the PCSs to recognize, orient, and assemble the constituent Smotifs of the target protein without any other experimental data or computational force fields. Using a universal Smotif database, the DINGO-PCS algorithm exhaustively enumerates any given Smotif. We benchmarked the program against ten different protein targets ranging from 100 to 220 residues with different topologies. For nine of these targets, the method was able to identify near-native Smotifs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Visualizing the global secondary structure of a viral RNA genome with cryo-electron microscopy.

    Science.gov (United States)

    Garmann, Rees F; Gopal, Ajaykumar; Athavale, Shreyas S; Knobler, Charles M; Gelbart, William M; Harvey, Stephen C

    2015-05-01

    The lifecycle, and therefore the virulence, of single-stranded (ss)-RNA viruses is regulated not only by their particular protein gene products, but also by the secondary and tertiary structure of their genomes. The secondary structure of the entire genomic RNA of satellite tobacco mosaic virus (STMV) was recently determined by selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE). The SHAPE analysis suggested a single highly extended secondary structure with much less branching than occurs in the ensemble of structures predicted by purely thermodynamic algorithms. Here we examine the solution-equilibrated STMV genome by direct visualization with cryo-electron microscopy (cryo-EM), using an RNA of similar length transcribed from the yeast genome as a control. The cryo-EM data reveal an ensemble of branching patterns that are collectively consistent with the SHAPE-derived secondary structure model. Thus, our results both elucidate the statistical nature of the secondary structure of large ss-RNAs and give visual support for modern RNA structure determination methods. Additionally, this work introduces cryo-EM as a means to distinguish between competing secondary structure models if the models differ significantly in terms of the number and/or length of branches. Furthermore, with the latest advances in cryo-EM technology, we suggest the possibility of developing methods that incorporate restraints from cryo-EM into the next generation of algorithms for the determination of RNA secondary and tertiary structures. © 2015 Garmann et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  17. GC content around splice sites affects splicing through pre-mRNA secondary structures

    Directory of Open Access Journals (Sweden)

    Chen Liang

    2011-01-01

    Full Text Available Abstract Background Alternative splicing increases protein diversity by generating multiple transcript isoforms from a single gene through different combinations of exons or through different selections of splice sites. It has been reported that RNA secondary structures are involved in alternative splicing. Here we perform a genomic study of RNA secondary structures around splice sites in humans (Homo sapiens, mice (Mus musculus, fruit flies (Drosophila melanogaster, and nematodes (Caenorhabditis elegans to further investigate this phenomenon. Results We observe that GC content around splice sites is closely associated with the splice site usage in multiple species. RNA secondary structure is the possible explanation, because the structural stability difference among alternative splice sites, constitutive splice sites, and skipped splice sites can be explained by the GC content difference. Alternative splice sites tend to be GC-enriched and exhibit more stable RNA secondary structures in all of the considered species. In humans and mice, splice sites of first exons and long exons tend to be GC-enriched and hence form more stable structures, indicating the special role of RNA secondary structures in promoter proximal splicing events and the splicing of long exons. In addition, GC-enriched exon-intron junctions tend to be overrepresented in tissue-specific alternative splice sites, indicating the functional consequence of the GC effect. Compared with regions far from splice sites and decoy splice sites, real splice sites are GC-enriched. We also found that the GC-content effect is much stronger than the nucleotide-order effect to form stable secondary structures. Conclusion All of these results indicate that GC content is related to splice site usage and it may mediate the splicing process through RNA secondary structures.

  18. Porous carbonaceous electrode structure and method for secondary electrochemical cell

    Science.gov (United States)

    Kaun, Thomas D.

    1977-03-08

    Positive and negative electrodes are provided as rigid, porous carbonaceous matrices with particulate active material fixedly embedded. Active material such as metal chalcogenides, solid alloys of alkali metal or alkaline earth metals along with other metals and their oxides in particulate form are blended with a thermosetting resin and a solid volatile to form a paste mixture. Various electrically conductive powders or current collector structures can be blended or embedded into the paste mixture which can be molded to the desired electrode shape. The molded paste is heated to a temperature at which the volatile transforms into vapor to impart porosity as the resin begins to cure into a rigid solid structure.

  19. Argumentation in Secondary School Students' Structured and Unstructured Chat Discussions

    Science.gov (United States)

    Salminen, Timo; Marttunen, Miika; Laurinen, Leena

    2012-01-01

    Joint construction of new knowledge demands that persons can express their statements in a convincing way and explore other people's arguments constructively. For this reason, more knowledge on different means to support collaborative argumentation is needed. This study clarifies whether structured interaction supports students' critical and…

  20. Cotranscriptional folding kinetics of ribonucleic acid secondary structures

    Science.gov (United States)

    Zhao, Peinan; Zhang, Wenbing; Chen, Shi-Jie

    2011-12-01

    We develop a systematic helix-based computational method to predict RNA folding kinetics during transcription. In our method, the transcription is modeled as stepwise process, where each step is the transcription of a nucleotide. For each step, the kinetics algorithm predicts the population kinetics, transition pathways, folding intermediates, and the transcriptional folding products. The folding pathways, rate constants, and the conformational populations for cotranscription folding show contrastingly different features than the refolding kinetics for a fully transcribed chain. The competition between the transcription speed and rate constants for the transitions between the different nascent structures determines the RNA folding pathway and the end product of folding. For example, fast transcription favors the formation of branch-like structures than rod-like structures and chain elongation in the folding process may reduce the probability of the formation of misfolded structures. Furthermore, good theory-experiment agreements suggest that our method may provide a reliable tool for quantitative prediction for cotranscriptional RNA folding, including the kinetics for the population distribution for the whole conformational ensemble.

  1. Secondary Structures Associated With Alkaline Transition of Horse ...

    African Journals Online (AJOL)

    acer

    et al., 1987; Lawal, 1999), and Raman spectroscopy (Davies .... composed of several underline components arising from various .... band components. It is clear from the result that the transition of ferricytochrome c has affected the β-turn structures in both content and number of components (figures 1, 2 and. 3). A significant ...

  2. Secondary Structure Adopted by the Gly-Gly-X Repetitive Regions of Dragline Spider Silk

    Directory of Open Access Journals (Sweden)

    Geoffrey M. Gray

    2016-12-01

    Full Text Available Solid-state NMR and molecular dynamics (MD simulations are presented to help elucidate the molecular secondary structure of poly(Gly-Gly-X, which is one of the most common structural repetitive motifs found in orb-weaving dragline spider silk proteins. The combination of NMR and computational experiments provides insight into the molecular secondary structure of poly(Gly-Gly-X segments and provides further support that these regions are disordered and primarily non-β-sheet. Furthermore, the combination of NMR and MD simulations illustrate the possibility for several secondary structural elements in the poly(Gly-Gly-X regions of dragline silks, including β-turns, 310-helicies, and coil structures with a negligible population of α-helix observed.

  3. Prediction of backbone dihedral angles and protein secondary structure using support vector machines

    Directory of Open Access Journals (Sweden)

    Hirst Jonathan D

    2009-12-01

    Full Text Available Abstract Background The prediction of the secondary structure of a protein is a critical step in the prediction of its tertiary structure and, potentially, its function. Moreover, the backbone dihedral angles, highly correlated with secondary structures, provide crucial information about the local three-dimensional structure. Results We predict independently both the secondary structure and the backbone dihedral angles and combine the results in a loop to enhance each prediction reciprocally. Support vector machines, a state-of-the-art supervised classification technique, achieve secondary structure predictive accuracy of 80% on a non-redundant set of 513 proteins, significantly higher than other methods on the same dataset. The dihedral angle space is divided into a number of regions using two unsupervised clustering techniques in order to predict the region in which a new residue belongs. The performance of our method is comparable to, and in some cases more accurate than, other multi-class dihedral prediction methods. Conclusions We have created an accurate predictor of backbone dihedral angles and secondary structure. Our method, called DISSPred, is available online at http://comp.chem.nottingham.ac.uk/disspred/.

  4. CSI 3.0: a web server for identifying secondary and super-secondary structure in proteins using NMR chemical shifts.

    Science.gov (United States)

    Hafsa, Noor E; Arndt, David; Wishart, David S

    2015-07-01

    The Chemical Shift Index or CSI 3.0 (http://csi3.wishartlab.com) is a web server designed to accurately identify the location of secondary and super-secondary structures in protein chains using only nuclear magnetic resonance (NMR) backbone chemical shifts and their corresponding protein sequence data. Unlike earlier versions of CSI, which only identified three types of secondary structure (helix, β-strand and coil), CSI 3.0 now identifies total of 11 types of secondary and super-secondary structures, including helices, β-strands, coil regions, five common β-turns (type I, II, I', II' and VIII), β hairpins as well as interior and edge β-strands. CSI 3.0 accepts experimental NMR chemical shift data in multiple formats (NMR Star 2.1, NMR Star 3.1 and SHIFTY) and generates colorful CSI plots (bar graphs) and secondary/super-secondary structure assignments. The output can be readily used as constraints for structure determination and refinement or the images may be used for presentations and publications. CSI 3.0 uses a pipeline of several well-tested, previously published programs to identify the secondary and super-secondary structures in protein chains. Comparisons with secondary and super-secondary structure assignments made via standard coordinate analysis programs such as DSSP, STRIDE and VADAR on high-resolution protein structures solved by X-ray and NMR show >90% agreement between those made with CSI 3.0. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

  5. Variable regions V13 and V3 of Saccharomyces cerevisiae contain structural features essential for normal biogenesis and stability of 5.8S and 25S rRNA

    NARCIS (Netherlands)

    Jeeninga, R. E.; van Delft, Y.; de Graaff-Vincent, M.; Dirks-Mulder, A.; Venema, J.; Raué, H. A.

    1997-01-01

    The homologous ribosomal RNA species of all organisms can be folded into a common "core" secondary structure. In addition, eukaryotic rRNAs contain a large number of segments, located at fixed positions, that are highly variable in size and sequence from one organism to another. We have investigated

  6. Insights into the structure, function and evolution of the radical-SAM 23S rRNA methyltransferase Cfr that confers antibiotic resistance in bacteria

    DEFF Research Database (Denmark)

    Karminska, K. H.; Purta, E.; Hansen, L .H.

    2010-01-01

    of a 4Fe-4S cluster, a SAM molecule coordinated to the iron-sulfur cluster (SAM1) and a SAM molecule that is the putative methyl group donor (SAM2). All mutations at predicted functional sites affect Cfr activity significantly as assayed by antibiotic susceptibility testing and primer extension analysis....... The investigation has identified essential amino acids and Cfr variants with altered reaction mechanisms and represents a first step towards understanding the structural basis of Cfr activity....

  7. Students' understanding of primary and secondary protein structure: drawing secondary protein structure reveals student understanding better than simple recognition of structures.

    Science.gov (United States)

    Harle, Marissa; Towns, Marcy H

    2013-01-01

    The interdisciplinary nature of biochemistry courses requires students to use both chemistry and biology knowledge to understand biochemical concepts. Research that has focused on external representations in biochemistry has uncovered student difficulties in comprehending and interpreting external representations in addition to a fragmented understanding of fundamental biochemistry concepts. This project focuses on students' understanding of primary and secondary protein structure and drawings (representations) of hydrogen-bonding in alpha helices and beta sheets. Analysis demonstrated that students can recognize and identify primary protein structure concepts when given a polypeptide. However, when asked to draw alpha helices and beta sheets and explain the role of hydrogen bonding their drawings students exhibited a fragmented understanding that lacked coherence. Faculty are encouraged to have students draw molecular level representations to make their mental models more explicit, complete, and coherent. This is in contrast to recognition and identification tasks, which do not adequately probe mental models and molecular level understanding. © 2013 by The International Union of Biochemistry and Molecular Biology.

  8. Analysis of an optimal hidden Markov model for secondary structure prediction

    Directory of Open Access Journals (Sweden)

    Gibrat Jean-François

    2006-12-01

    Full Text Available Abstract Background Secondary structure prediction is a useful first step toward 3D structure prediction. A number of successful secondary structure prediction methods use neural networks, but unfortunately, neural networks are not intuitively interpretable. On the contrary, hidden Markov models are graphical interpretable models. Moreover, they have been successfully used in many bioinformatic applications. Because they offer a strong statistical background and allow model interpretation, we propose a method based on hidden Markov models. Results Our HMM is designed without prior knowledge. It is chosen within a collection of models of increasing size, using statistical and accuracy criteria. The resulting model has 36 hidden states: 15 that model α-helices, 12 that model coil and 9 that model β-strands. Connections between hidden states and state emission probabilities reflect the organization of protein structures into secondary structure segments. We start by analyzing the model features and see how it offers a new vision of local structures. We then use it for secondary structure prediction. Our model appears to be very efficient on single sequences, with a Q3 score of 68.8%, more than one point above PSIPRED prediction on single sequences. A straightforward extension of the method allows the use of multiple sequence alignments, rising the Q3 score to 75.5%. Conclusion The hidden Markov model presented here achieves valuable prediction results using only a limited number of parameters. It provides an interpretable framework for protein secondary structure architecture. Furthermore, it can be used as a tool for generating protein sequences with a given secondary structure content.

  9. ITS1, 5.8S and ITS2 secondary structure modelling for intra-specific differentiation among species of the Colletotrichum gloeosporioides sensu lato species complex.

    Science.gov (United States)

    Rampersad, Sephra N

    2014-01-01

    The Colletotrichum gloeosporioides species complex is among the most destructive fungal plant pathogens in the world, however, identification of member species which are of quarantine importance is impacted by a number of factors that negatively affect species identification. Structural information of the rRNA marker may be considered to be a conserved marker which can be used as supplementary information for possible species identification. The difficulty in using ITS rDNA sequences for identification lies in the low level of sequence variation at the intra-specific level and the generation of artificially-induced sequence variation due to errors in polymerization of the ITS array during DNA replication. Type and query ITS sequences were subjected to sequence analyses prior to generation of predicted consensus secondary structures, including the pattern of nucleotide polymorphisms and number of indel haplotypes, GC content, and detection of artificially-induced sequence variation. Data pertaining to structure stability, the presence of conserved motifs in secondary structures and mapping of all sequences onto the consensus C. gloeosporioides sensu stricto secondary structure for ITS1, 5.8S and ITS2 markers was then carried out. Motifs that are evolutionarily conserved among eukaryotes were found for all ITS1, 5.8S and ITS2 sequences. The sequences exhibited conserved features typical of functional rRNAs. Generally, polymorphisms occurred within less conserved regions and were seen as bulges, internal and terminal loops or non-canonical G-U base-pairs within regions of the double stranded helices. Importantly, there were also taxonomic motifs and base changes that were unique to specific taxa and which may be used to support intra-specific identification of members of the C. gloeosporioides sensu lato species complex.

  10. Molecular phylogeny of 21 tropical bamboo species reconstructed by integrating non-coding internal transcribed spacer (ITS1 and 2) sequences and their consensus secondary structure.

    Science.gov (United States)

    Ghosh, Jayadri Sekhar; Bhattacharya, Samik; Pal, Amita

    2017-06-01

    The unavailability of the reproductive structure and unpredictability of vegetative characters for the identification and phylogenetic study of bamboo prompted the application of molecular techniques for greater resolution and consensus. We first employed internal transcribed spacer (ITS1, 5.8S rRNA and ITS2) sequences to construct the phylogenetic tree of 21 tropical bamboo species. While the sequence alone could grossly reconstruct the traditional phylogeny amongst the 21-tropical species studied, some anomalies were encountered that prompted a further refinement of the phylogenetic analyses. Therefore, we integrated the secondary structure of the ITS sequences to derive individual sequence-structure matrix to gain more resolution on the phylogenetic reconstruction. The results showed that ITS sequence-structure is the reliable alternative to the conventional phenotypic method for the identification of bamboo species. The best-fit topology obtained by the sequence-structure based phylogeny over the sole sequence based one underscores closer clustering of all the studied Bambusa species (Sub-tribe Bambusinae), while Melocanna baccifera, which belongs to Sub-Tribe Melocanneae, disjointedly clustered as an out-group within the consensus phylogenetic tree. In this study, we demonstrated the dependability of the combined (ITS sequence+structure-based) approach over the only sequence-based analysis for phylogenetic relationship assessment of bamboo.

  11. GTfold: Enabling parallel RNA secondary structure prediction on multi-core desktops

    DEFF Research Database (Denmark)

    Swenson, M Shel; Anderson, Joshua; Ash, Andrew

    2012-01-01

    Accurate and efficient RNA secondary structure prediction remains an important open problem in computational molecular biology. Historically, advances in computing technology have enabled faster and more accurate RNA secondary structure predictions. Previous parallelized prediction programs...... achieved significant improvements in runtime, but their implementations were not portable from niche high-performance computers or easily accessible to most RNA researchers. With the increasing prevalence of multi-core desktop machines, a new parallel prediction program is needed to take full advantage......, on machines with four or more cores. Conclusions GTfold supports advances in RNA structural biology by reducing the timescales for secondary structure prediction. The difference will be particularly valuable to researchers working with lengthy RNA sequences, such as RNA viral genomes....

  12. Evolving stochastic context-free grammars for RNA secondary structure prediction

    DEFF Research Database (Denmark)

    Anderson, James WJ; Tataru, Paula Cristina; Stains, Joe

    2012-01-01

    with quite different structure could have very similar predictive ability. Many ambiguous grammars were found which were at least as effective as the best current unambiguous grammars. Conclusions Overall the method of evolving SCFGs for RNA secondary structure prediction proved effective in finding many...... grammars that had strong predictive accuracy, as good or slightly better than those designed manually. Furthermore, several of the best grammars found were ambiguous, demonstrating that such grammars should not be disregarded.......Background Stochastic Context-Free Grammars (SCFGs) were applied successfully to RNA secondary structure prediction in the early 90s, and used in combination with comparative methods in the late 90s. The set of SCFGs potentially useful for RNA secondary structure prediction is very large, but a few...

  13. Relationship between Secondary Structure and Surface Hydrophobicity of Soybean Protein Isolate Subjected to Heat Treatment

    Directory of Open Access Journals (Sweden)

    Zhongjiang Wang

    2014-01-01

    Full Text Available This study investigated relationship between secondary structure and surface hydrophobicity of soy protein isolate (SPI subjected to a thermal treatment at 70~90°C. Heat denaturation increased the surface hydrophobicity and surface hydrophobicity decreased as aggregate formed. Heat caused an increase in the relative amount of α-helix structures and an overall decrease in the amount of β-sheet structures when compared with nontreated SPI. The relative amounts of secondary structures varied with time, temperature, and intensity of heat treatment applied. The β-sheet structure was most important for its significant role in denaturation of 7S globulin and following formed aggregates and even in denaturation of 11S globulin. The amount of β-sheet structure in SPI had an inverse correlation with the surface hydrophobicity when the temperature was kept below 90°C. Besides, β-turn structure increased as β-7S/B-11S aggregate formated.

  14. Secondary Structure Predictions for Long RNA Sequences Based on Inversion Excursions and MapReduce.

    Science.gov (United States)

    Yehdego, Daniel T; Zhang, Boyu; Kodimala, Vikram K R; Johnson, Kyle L; Taufer, Michela; Leung, Ming-Ying

    2013-05-01

    Secondary structures of ribonucleic acid (RNA) molecules play important roles in many biological processes including gene expression and regulation. Experimental observations and computing limitations suggest that we can approach the secondary structure prediction problem for long RNA sequences by segmenting them into shorter chunks, predicting the secondary structures of each chunk individually using existing prediction programs, and then assembling the results to give the structure of the original sequence. The selection of cutting points is a crucial component of the segmenting step. Noting that stem-loops and pseudoknots always contain an inversion, i.e., a stretch of nucleotides followed closely by its inverse complementary sequence, we developed two cutting methods for segmenting long RNA sequences based on inversion excursions: the centered and optimized method. Each step of searching for inversions, chunking, and predictions can be performed in parallel. In this paper we use a MapReduce framework, i.e., Hadoop, to extensively explore meaningful inversion stem lengths and gap sizes for the segmentation and identify correlations between chunking methods and prediction accuracy. We show that for a set of long RNA sequences in the RFAM database, whose secondary structures are known to contain pseudoknots, our approach predicts secondary structures more accurately than methods that do not segment the sequence, when the latter predictions are possible computationally. We also show that, as sequences exceed certain lengths, some programs cannot computationally predict pseudoknots while our chunking methods can. Overall, our predicted structures still retain the accuracy level of the original prediction programs when compared with known experimental secondary structure.

  15. Secondary structure in the target as a confounding factor in synthetic oligomer microarray design

    Directory of Open Access Journals (Sweden)

    Gibas Cynthia J

    2005-03-01

    Full Text Available Abstract Background Secondary structure in the target is a property not usually considered in software applications for design of optimal custom oligonucleotide probes. It is frequently assumed that eliminating self-complementarity, or screening for secondary structure in the probe, is sufficient to avoid interference with hybridization by stable secondary structures in the probe binding site. Prediction and thermodynamic analysis of secondary structure formation in a genome-wide set of transcripts from Brucella suis 1330 demonstrates that the properties of the target molecule have the potential to strongly influence the rate and extent of hybridization between transcript and tethered oligonucleotide probe in a microarray experiment. Results Despite the relatively high hybridization temperatures and 1M monovalent salt imposed in the modeling process to approximate hybridization conditions used in the laboratory, we find that parts of the target molecules are likely to be inaccessible to intermolecular hybridization due to the formation of stable intramolecular secondary structure. For example, at 65°C, 28 ± 7% of the average cDNA target sequence is predicted to be inaccessible to hybridization. We also analyzed the specific binding sites of a set of 70mer probes previously designed for Brucella using a freely available oligo design software package. 21 ± 13% of the nucleotides in each probe binding site are within a double-stranded structure in over half of the folds predicted for the cDNA target at 65°C. The intramolecular structures formed are more stable and extensive when an RNA target is modeled rather than cDNA. When random shearing of the target is modeled for fragments of 200, 100 and 50 nt, an overall destabilization of secondary structure is predicted, but shearing does not eliminate secondary structure. Conclusion Secondary structure in the target is pervasive, and a significant fraction of the target is found in double stranded

  16. SAAS: Short Amino Acid Sequence - A Promising Protein Secondary Structure Prediction Method of Single Sequence

    Directory of Open Access Journals (Sweden)

    Zhou Yuan Wu

    2013-07-01

    Full Text Available In statistical methods of predicting protein secondary structure, many researchers focus on single amino acid frequencies in α-helices, β-sheets, and so on, or the impact near amino acids on an amino acid forming a secondary structure. But the paper considers a short sequence of amino acids (3, 4, 5 or 6 amino acids as integer, and statistics short sequence's probability forming secondary structure. Also, many researchers select low homologous sequences as statistical database. But this paper select whole PDB database. In this paper we propose a strategy to predict protein secondary structure using simple statistical method. Numerical computation shows that, short amino acids sequence as integer to statistics, which can easy see trend of short sequence forming secondary structure, and it will work well to select large statistical database (whole PDB database without considering homologous, and Q3 accuracy is ca. 74% using this paper proposed simple statistical method, but accuracy of others statistical methods is less than 70%.

  17. RNA Secondary Structure Prediction by Using Discrete Mathematics: An Interdisciplinary Research Experience for Undergraduate Students

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    Ellington, Roni; Wachira, James

    2010-01-01

    The focus of this Research Experience for Undergraduates (REU) project was on RNA secondary structure prediction by using a lattice walk approach. The lattice walk approach is a combinatorial and computational biology method used to enumerate possible secondary structures and predict RNA secondary structure from RNA sequences. The method uses discrete mathematical techniques and identifies specified base pairs as parameters. The goal of the REU was to introduce upper-level undergraduate students to the principles and challenges of interdisciplinary research in molecular biology and discrete mathematics. At the beginning of the project, students from the biology and mathematics departments of a mid-sized university received instruction on the role of secondary structure in the function of eukaryotic RNAs and RNA viruses, RNA related to combinatorics, and the National Center for Biotechnology Information resources. The student research projects focused on RNA secondary structure prediction on a regulatory region of the yellow fever virus RNA genome and on an untranslated region of an mRNA of a gene associated with the neurological disorder epilepsy. At the end of the project, the REU students gave poster and oral presentations, and they submitted written final project reports to the program director. The outcome of the REU was that the students gained transferable knowledge and skills in bioinformatics and an awareness of the applications of discrete mathematics to biological research problems. PMID:20810968

  18. Using chemical shifts to generate structural ensembles for intrinsically disordered proteins with converged distributions of secondary structure.

    Science.gov (United States)

    Ytreberg, F Marty; Borcherds, Wade; Wu, Hongwei; Daughdrill, Gary W

    2015-01-01

    A short segment of the disordered p53 transactivation domain (p53TAD) forms an amphipathic helix when bound to the E3 ubiquitin ligase, MDM2. In the unbound p53TAD, this short segment has transient helical secondary structure. Using a method that combines broad sampling of conformational space with re-weighting, it is shown that it is possible to generate multiple, independent structural ensembles that have highly similar secondary structure distributions for both p53TAD and a P27A mutant. Fractional amounts of transient helical secondary structure were found at the MDM2 binding site that are very similar to estimates based directly on experimental observations. Structures were identified in these ensembles containing segments that are highly similar to short p53 peptides bound to MDM2, even though the ensembles were re-weighted using unbound experimental data. Ensembles were generated using chemical shift data (alpha carbon only, or in combination with other chemical shifts) and cross-validated by predicting residual dipolar couplings. We think this ensemble generator could be used to predict the bound state structure of protein interaction sites in IDPs if there are detectable amounts of matching transient secondary structure in the unbound state.

  19. A theoretical analysis of secondary structural characteristics of anticancer peptides.

    Science.gov (United States)

    Dennison, Sarah R; Harris, Frederick; Bhatt, Tailap; Singh, Jaipaul; Phoenix, David A

    2010-01-01

    Here, cluster analysis showed that a database of 158 anticancer peptides formed 21 clusters based on net positive charge, hydrophobicity and amphiphilicity. In general, these clusters showed similar median toxicities (P = 0.176) against eukaryotic cell lines and no single combination of these properties was found optimal for efficacy. The database contained 14 peptides, which showed selectivity for tumour cell lines only (ACP(CT)), 123 peptides with general toxicity to eukaryotic cells (ACP(GT)) and 21 inactive peptides (ACP(I)). Hydrophobic arc size analysis showed that there was no significant difference across the datasets although peptides with wide hydrophobic arcs (>270 degrees) appeared to be associated with decreased toxicity. Extended hydrophobic moment plot analysis predicted that over 50% of ACP(CT) and ACP(GT) peptides would be surface active, which led to the suggestion that amphiphilicity is a key driver of the membrane interactions for these peptides but probably plays a role in their efficacy rather than their selectivity. This analysis also predicted that only 14% of ACP(CT) peptides compared to 45% of ACP(GT) peptides were candidates for tilted peptide formation, which led to the suggestion that the absence of this structure may support cancer cell selectivity. However, these analyses predicted that ACP(I) peptides, which possess no anticancer activity, would also form surface active and tilted alpha-helices, clearly showing that other factors are involved in determining the efficacy and selectivity of ACPs.

  20. Geographical variation in soil bacterial community structure in tropical forests in Southeast Asia and temperate forests in Japan based on pyrosequencing analysis of 16S rRNA.

    Science.gov (United States)

    Ito, Natsumi; Iwanaga, Hiroko; Charles, Suliana; Diway, Bibian; Sabang, John; Chong, Lucy; Nanami, Satoshi; Kamiya, Koichi; Lum, Shawn; Siregar, Ulfah J; Harada, Ko; Miyashita, Naohiko T

    2017-09-12

    Geographical variation in soil bacterial community structure in 26 tropical forests in Southeast Asia (Malaysia, Indonesia and Singapore) and two temperate forests in Japan was investigated to elucidate the environmental factors and mechanisms that influence biogeography of soil bacterial diversity and composition. Despite substantial environmental differences, bacterial phyla were represented in similar proportions, with Acidobacteria and Proteobacteria the dominant phyla in all forests except one mangrove forest in Sarawak, although highly significant heterogeneity in frequency of individual phyla was detected among forests. In contrast, species diversity (α-diversity) differed to a much greater extent, being nearly six-fold higher in the mangrove forest (Chao1 index = 6,862) than in forests in Singapore and Sarawak (~1,250). In addition, natural mixed dipterocarp forests had lower species diversity than acacia and oil palm plantations, indicating that aboveground tree composition does not influence soil bacterial diversity. Shannon and Chao1 indices were correlated positively, implying that skewed operational taxonomic unit (OTU) distribution was associated with the abundance of overall and rare (singleton) OTUs. No OTUs were represented in all 28 forests, and forest-specific OTUs accounted for over 70% of all detected OTUs. Forests that were geographically adjacent and/or of the same forest type had similar bacterial species composition, and a positive correlation was detected between species divergence (β-diversity) and direct distance between forests. Both α- and β-diversities were correlated with soil pH. These results suggest that soil bacterial communities in different forests evolve largely independently of each other and that soil bacterial communities adapt to their local environment, modulated by bacterial dispersal (distance effect) and forest type. Therefore, we conclude that the biogeography of soil bacteria communities described here is non

  1. The FT-IR spectrometric analysis of the changes of polyphenol oxidase II secondary structure

    Science.gov (United States)

    Shi, Chunhua; Dai, Ya; Liu, Qingliang; Xie, Yongshu; Xu, Xiaolong

    2003-01-01

    Polyphenol oxidase II is a novel protein purified from tobacco, which acts as a key role in plant defense system. From the analysis of FT-IR spectrums, Fourier self-deconvolution (FSD) spectrums and second-derivative spectrums of PPO II at different pH and peroxide PPO II adduct, the secondary structure fractions are analyzed. PPO II at low pH (pH=3.0) and peroxide PPO II adduct almost keep the same secondary structure of native PPO II. The percentages of β-turn and random coil increase rapidly and the percentages of α-helix and anti-parallel β-sheet decrease rapidly at high pH (pH=10.0) comparing with that of native PPO II. All these conclusions are proved by the secondary structure calculations of circular dichroism spectrums in different states.

  2. Accurate secondary structure prediction and fold recognition for circular dichroism spectroscopy.

    Science.gov (United States)

    Micsonai, András; Wien, Frank; Kernya, Linda; Lee, Young-Ho; Goto, Yuji; Réfrégiers, Matthieu; Kardos, József

    2015-06-16

    Circular dichroism (CD) spectroscopy is a widely used technique for the study of protein structure. Numerous algorithms have been developed for the estimation of the secondary structure composition from the CD spectra. These methods often fail to provide acceptable results on α/β-mixed or β-structure-rich proteins. The problem arises from the spectral diversity of β-structures, which has hitherto been considered as an intrinsic limitation of the technique. The predictions are less reliable for proteins of unusual β-structures such as membrane proteins, protein aggregates, and amyloid fibrils. Here, we show that the parallel/antiparallel orientation and the twisting of the β-sheets account for the observed spectral diversity. We have developed a method called β-structure selection (BeStSel) for the secondary structure estimation that takes into account the twist of β-structures. This method can reliably distinguish parallel and antiparallel β-sheets and accurately estimates the secondary structure for a broad range of proteins. Moreover, the secondary structure components applied by the method are characteristic to the protein fold, and thus the fold can be predicted to the level of topology in the CATH classification from a single CD spectrum. By constructing a web server, we offer a general tool for a quick and reliable structure analysis using conventional CD or synchrotron radiation CD (SRCD) spectroscopy for the protein science research community. The method is especially useful when X-ray or NMR techniques fail. Using BeStSel on data collected by SRCD spectroscopy, we investigated the structure of amyloid fibrils of various disease-related proteins and peptides.

  3. Web-Beagle: a web server for the alignment of RNA secondary structures.

    Science.gov (United States)

    Mattei, Eugenio; Pietrosanto, Marco; Ferrè, Fabrizio; Helmer-Citterich, Manuela

    2015-07-01

    Web-Beagle (http://beagle.bio.uniroma2.it) is a web server for the pairwise global or local alignment of RNA secondary structures. The server exploits a new encoding for RNA secondary structure and a substitution matrix of RNA structural elements to perform RNA structural alignments. The web server allows the user to compute up to 10 000 alignments in a single run, taking as input sets of RNA sequences and structures or primary sequences alone. In the latter case, the server computes the secondary structure prediction for the RNAs on-the-fly using RNAfold (free energy minimization). The user can also compare a set of input RNAs to one of five pre-compiled RNA datasets including lncRNAs and 3' UTRs. All types of comparison produce in output the pairwise alignments along with structural similarity and statistical significance measures for each resulting alignment. A graphical color-coded representation of the alignments allows the user to easily identify structural similarities between RNAs. Web-Beagle can be used for finding structurally related regions in two or more RNAs, for the identification of homologous regions or for functional annotation. Benchmark tests show that Web-Beagle has lower computational complexity, running time and better performances than other available methods. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

  4. "Parallel factor analysis of multi-excitation ultraviolet resonance Raman spectra for protein secondary structure determination".

    Science.gov (United States)

    Oshokoya, Olayinka O; JiJi, Renee D

    2015-09-10

    Protein secondary structural analysis is important for understanding the relationship between protein structure and function, or more importantly how changes in structure relate to loss of function. The structurally sensitive protein vibrational modes (amide I, II, III and S) in deep-ultraviolet resonance Raman (DUVRR) spectra resulting from the backbone C-O and N-H vibrations make DUVRR a potentially powerful tool for studying secondary structure changes. Experimental studies reveal that the position and intensity of the four amide modes in DUVRR spectra of proteins are largely correlated with the varying fractions of α-helix, β-sheet and disordered structural content of proteins. Employing multivariate calibration methods and DUVRR spectra of globular proteins with varying structural compositions, the secondary structure of a protein with unknown structure can be predicted. A disadvantage of multivariate calibration methods is the requirement of known concentration or spectral profiles. Second-order curve resolution methods, such as parallel factor analysis (PARAFAC), do not have such a requirement due to the "second-order advantage." An exceptional feature of DUVRR spectroscopy is that DUVRR spectra are linearly dependent on both excitation wavelength and secondary structure composition. Thus, higher order data can be created by combining protein DUVRR spectra of several proteins collected at multiple excitation wavelengths to give multi-excitation ultraviolet resonance Raman data (ME-UVRR). PARAFAC has been used to analyze ME-UVRR data of nine proteins to resolve the pure spectral, excitation and compositional profiles. A three factor model with non-negativity constraints produced three unique factors that were correlated with the relative abundance of helical, β-sheet and poly-proline II dihedral angles. This is the first empirical evidence that the typically resolved "disordered" spectrum represents the better defined poly-proline II type structure

  5. A 9-state hidden Markov model using protein secondary structure information for protein fold recognition.

    Science.gov (United States)

    Lee, Sun Young; Lee, Jong Yun; Jung, Kwang Su; Ryu, Keun Ho

    2009-06-01

    In protein fold recognition, the main disadvantage of hidden Markov models (HMMs) is the employment of large-scale model architectures which require large data sets and high computational resources for training. Also, HMMs must consider sequential information about secondary structures of proteins, to improve prediction performance and reduce model parameters. Therefore, we propose a novel method for protein fold recognition based on a hidden Markov model, called a 9-state HMM. The method can (i) reduce the number of states using secondary structure information about proteins for each fold and (ii) recognize protein folds more accurately than other HMMs.

  6. Artificial Intelligence in Prediction of Secondary Protein Structure Using CB513 Database.

    Science.gov (United States)

    Avdagic, Zikrija; Purisevic, Elvir; Omanovic, Samir; Coralic, Zlatan

    2009-03-01

    In this paper we describe CB513 a non-redundant dataset, suitable for development of algorithms for prediction of secondary protein structure. A program was made in Borland Delphi for transforming data from our dataset to make it suitable for learning of neural network for prediction of secondary protein structure implemented in MATLAB Neural-Network Toolbox. Learning (training and testing) of neural network is researched with different sizes of windows, different number of neurons in the hidden layer and different number of training epochs, while using dataset CB513.

  7. RNACompress: Grammar-based compression and informational complexity measurement of RNA secondary structure.

    Science.gov (United States)

    Liu, Qi; Yang, Yu; Chen, Chun; Bu, Jiajun; Zhang, Yin; Ye, Xiuzi

    2008-03-31

    With the rapid emergence of RNA databases and newly identified non-coding RNAs, an efficient compression algorithm for RNA sequence and structural information is needed for the storage and analysis of such data. Although several algorithms for compressing DNA sequences have been proposed, none of them are suitable for the compression of RNA sequences with their secondary structures simultaneously. This kind of compression not only facilitates the maintenance of RNA data, but also supplies a novel way to measure the informational complexity of RNA structural data, raising the possibility of studying the relationship between the functional activities of RNA structures and their complexities, as well as various structural properties of RNA based on compression. RNACompress employs an efficient grammar-based model to compress RNA sequences and their secondary structures. The main goals of this algorithm are two fold: (1) present a robust and effective way for RNA structural data compression; (2) design a suitable model to represent RNA secondary structure as well as derive the informational complexity of the structural data based on compression. Our extensive tests have shown that RNACompress achieves a universally better compression ratio compared with other sequence-specific or common text-specific compression algorithms, such as Gencompress, winrar and gzip. Moreover, a test of the activities of distinct GTP-binding RNAs (aptamers) compared with their structural complexity shows that our defined informational complexity can be used to describe how complexity varies with activity. These results lead to an objective means of comparing the functional properties of heteropolymers from the information perspective. A universal algorithm for the compression of RNA secondary structure as well as the evaluation of its informational complexity is discussed in this paper. We have developed RNACompress, as a useful tool for academic users. Extensive tests have shown that

  8. RNACompress: Grammar-based compression and informational complexity measurement of RNA secondary structure

    Directory of Open Access Journals (Sweden)

    Chen Chun

    2008-03-01

    Full Text Available Abstract Background With the rapid emergence of RNA databases and newly identified non-coding RNAs, an efficient compression algorithm for RNA sequence and structural information is needed for the storage and analysis of such data. Although several algorithms for compressing DNA sequences have been proposed, none of them are suitable for the compression of RNA sequences with their secondary structures simultaneously. This kind of compression not only facilitates the maintenance of RNA data, but also supplies a novel way to measure the informational complexity of RNA structural data, raising the possibility of studying the relationship between the functional activities of RNA structures and their complexities, as well as various structural properties of RNA based on compression. Results RNACompress employs an efficient grammar-based model to compress RNA sequences and their secondary structures. The main goals of this algorithm are two fold: (1 present a robust and effective way for RNA structural data compression; (2 design a suitable model to represent RNA secondary structure as well as derive the informational complexity of the structural data based on compression. Our extensive tests have shown that RNACompress achieves a universally better compression ratio compared with other sequence-specific or common text-specific compression algorithms, such as Gencompress, winrar and gzip. Moreover, a test of the activities of distinct GTP-binding RNAs (aptamers compared with their structural complexity shows that our defined informational complexity can be used to describe how complexity varies with activity. These results lead to an objective means of comparing the functional properties of heteropolymers from the information perspective. Conclusion A universal algorithm for the compression of RNA secondary structure as well as the evaluation of its informational complexity is discussed in this paper. We have developed RNACompress, as a useful tool

  9. Detection of the new cosmopolitan genus Thermoleptolyngbya (Cyanobacteria, Leptolyngbyaceae) using the 16S rRNA gene and 16S-23S ITS region.

    Science.gov (United States)

    Sciuto, Katia; Moro, Isabella

    2016-12-01

    Cyanobacteria are widespread prokaryotes that are able to live in extreme conditions such as thermal springs. Strains attributable to the genus Leptolyngbya are among the most common cyanobacteria sampled from thermal environments. Leptolyngbya is a character-poor taxon that was demonstrated to be polyphyletic based on molecular analyses. The recent joining of 16S rRNA gene phylogenies with 16S-23S ITS secondary structure analysis is a useful approach to detect new cryptic taxa and has led to the separation of new genera from Leptolyngbya and to the description of new species inside this genus and in other related groups. In this study, phylogenetic investigations based on both the 16S rRNA gene and the 16S-23S ITS region were performed alongside 16S rRNA and 16S-23S ITS secondary structure analyses on cyanobacteria of the family Leptolyngbyaceae. These analyses focused on filamentous strains sampled from thermal springs with a morphology ascribable to the genus Leptolyngbya. The phylogenetic reconstructions showed that the Leptolyngbya-like thermal strains grouped into a monophyletic lineage that was distinct from Leptolyngbya. The 16S-23S ITS secondary structure results supported the separation of this cluster. A new genus named Thermoleptolyngbya was erected to encompass these strains, and two species were described inside this new taxon: T. albertanoae and T. oregonensis. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. FlexStem: improving predictions of RNA secondary structures with pseudoknots by reducing the search space.

    Science.gov (United States)

    Chen, Xiang; He, Si-Min; Bu, Dongbo; Zhang, Fa; Wang, Zhiyong; Chen, Runsheng; Gao, Wen

    2008-09-15

    RNA secondary structures with pseudoknots are often predicted by minimizing free energy, which is proved to be NP-hard. Due to kinetic reasons the real RNA secondary structure often has local instead of global minimum free energy. This implies that we may improve the performance of RNA secondary structure prediction by taking kinetics into account and minimize free energy in a local area. we propose a novel algorithm named FlexStem to predict RNA secondary structures with pseudoknots. Still based on MFE criterion, FlexStem adopts comprehensive energy models that allow complex pseudoknots. Unlike classical thermodynamic methods, our approach aims to simulate the RNA folding process by successive addition of maximal stems, reducing the search space while maintaining or even improving the prediction accuracy. This reduced space is constructed by our maximal stem strategy and stem-adding rule induced from elaborate statistical experiments on real RNA secondary structures. The strategy and the rule also reflect the folding characteristic of RNA from a new angle and help compensate for the deficiency of merely relying on MFE in RNA structure prediction. We validate FlexStem by applying it to tRNAs, 5SrRNAs and a large number of pseudoknotted structures and compare it with the well-known algorithms such as RNAfold, PKNOTS, PknotsRG, HotKnots and ILM according to their overall sensitivities and specificities, as well as positive and negative controls on pseudoknots. The results show that FlexStem significantly increases the prediction accuracy through its local search strategy. Software is available at http://pfind.ict.ac.cn/FlexStem/. Supplementary data are available at Bioinformatics online.

  11. Molecular Characterization and Postsplicing Fate of Three Introns within the Single rRNA Operon of the Hyperthermophilic Archaeon Aeropyrum pernix K1

    Science.gov (United States)

    Nomura, Norimichi; Sako, Yoshihiko; Uchida, Aritsune

    1998-01-01

    The single rRNA operon (arnS-arnL) of the hyperthermophilic archaeon Aeropyrum pernix K1 was sequenced. The DNA sequence data and detailed RNA analyses disclosed an unusual feature: the presence of three introns at hitherto undescribed insertion positions within the rRNA genes. The 699-nucleotide (nt) intron Iα was located at position 908 (Escherichia coli numbering [H. F. Noller, Annu. Rev. Biochem. 53:119–162, 1984]) of the 16S rRNA, while the 202-nt intron Iβ and 575-nt intron Iγ were located at positions 1085 and 1927 (E. coli numbering), respectively, of the 23S rRNA. They were located within highly conserved sites which have been implicated as crucial for rRNA function in E. coli. All three introns were remarkably AT rich (41.5 to 43.1 mol% G+C) compared with the mature rRNAs (67.7 and 69.2 mol% G+C for 16S and 23S rRNAs, respectively). No obvious primary sequence similarities were detected among them. After splicing from rRNA transcripts in vivo, a large quantity of intronic RNAs were stably retained in the linear monomeric form, whereas a trace of topoisomeric RNA molecules also appeared, as characterized by their behavior in two-dimensional gel electrophoresis. Secondary structural models of the Iα-, Iβ-, and Iγ-containing rRNA precursors agree with the bulge-helix-bulge motif. Two of the introns, Iα and Iγ, contained open reading frames whose protein translation exhibited no overall similarity with proteins reported so far. However, both share a LAGLI-DADG motif characteristic of homing endonucleases. PMID:9658008

  12. Viral IRES prediction system - a web server for prediction of the IRES secondary structure in silico.

    Directory of Open Access Journals (Sweden)

    Jun-Jie Hong

    Full Text Available The internal ribosomal entry site (IRES functions as cap-independent translation initiation sites in eukaryotic cells. IRES elements have been applied as useful tools for bi-cistronic expression vectors. Current RNA structure prediction programs are unable to predict precisely the potential IRES element. We have designed a viral IRES prediction system (VIPS to perform the IRES secondary structure prediction. In order to obtain better results for the IRES prediction, the VIPS can evaluate and predict for all four different groups of IRESs with a higher accuracy. RNA secondary structure prediction, comparison, and pseudoknot prediction programs were implemented to form the three-stage procedure for the VIPS. The backbone of VIPS includes: the RNAL fold program, aimed to predict local RNA secondary structures by minimum free energy method; the RNA Align program, intended to compare predicted structures; and pknotsRG program, used to calculate the pseudoknot structure. VIPS was evaluated by using UTR database, IRES database and Virus database, and the accuracy rate of VIPS was assessed as 98.53%, 90.80%, 82.36% and 80.41% for IRES groups 1, 2, 3, and 4, respectively. This advance useful search approach for IRES structures will facilitate IRES related studies. The VIPS on-line website service is available at http://140.135.61.250/vips/.

  13. Exact calculation of loop formation probability identifies folding motifs in RNA secondary structures.

    Science.gov (United States)

    Sloma, Michael F; Mathews, David H

    2016-12-01

    RNA secondary structure prediction is widely used to analyze RNA sequences. In an RNA partition function calculation, free energy nearest neighbor parameters are used in a dynamic programming algorithm to estimate statistical properties of the secondary structure ensemble. Previously, partition functions have largely been used to estimate the probability that a given pair of nucleotides form a base pair, the conditional stacking probability, the accessibility to binding of a continuous stretch of nucleotides, or a representative sample of RNA structures. Here it is demonstrated that an RNA partition function can also be used to calculate the exact probability of formation of hairpin loops, internal loops, bulge loops, or multibranch loops at a given position. This calculation can also be used to estimate the probability of formation of specific helices. Benchmarking on a set of RNA sequences with known secondary structures indicated that loops that were calculated to be more probable were more likely to be present in the known structure than less probable loops. Furthermore, highly probable loops are more likely to be in the known structure than the set of loops predicted in the lowest free energy structures. © 2016 Sloma and Mathews; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  14. Prediction of protein secondary structure using probability based features and a hybrid system.

    Science.gov (United States)

    Ghanty, Pradip; Pal, Nikhil R; Mudi, Rajani K

    2013-10-01

    In this paper, we propose some co-occurrence probability-based features for prediction of protein secondary structure. The features are extracted using occurrence/nonoccurrence of secondary structures in the protein sequences. We explore two types of features: position-specific (based on position of amino acid on fragments of protein sequences) as well as position-independent (independent of amino acid position on fragments of protein sequences). We use a hybrid system, NEUROSVM, consisting of neural networks and support vector machines for classification of secondary structures. We propose two schemes NSVMps and NSVM for protein secondary structure prediction. The NSVMps uses position-specific probability-based features and NEUROSVM classifier whereas NSVM uses the same classifier with position-independent probability-based features. The proposed method falls in the single-sequence category of methods because it does not use any sequence profile information such as position specific scoring matrices (PSSM) derived from PSI-BLAST. Two widely used datasets RS126 and CB513 are used in the experiments. The results obtained using the proposed features and NEUROSVM classifier are better than most of the existing single-sequence prediction methods. Most importantly, the results using NSVMps that are obtained using lower dimensional features, are comparable to those by other existing methods. The NSVMps and NSVM are finally tested on target proteins of the critical assessment of protein structure prediction experiment-9 (CASP9). A larger dataset is used to compare the performance of the proposed methods with that of two recent single-sequence prediction methods. We also investigate the impact of presence of different amino acid residues (in protein sequences) that are responsible for the formation of different secondary structures.

  15. mRNA secondary structures fold sequentially but exchange rapidly in vivo.

    Directory of Open Access Journals (Sweden)

    Elisabeth M Mahen

    2010-02-01

    Full Text Available RNAs adopt defined structures to perform biological activities, and conformational transitions among alternative structures are critical to virtually all RNA-mediated processes ranging from metabolite-activation of bacterial riboswitches to pre-mRNA splicing and viral replication in eukaryotes. Mechanistic analysis of an RNA folding reaction in a biological context is challenging because many steps usually intervene between assembly of a functional RNA structure and execution of a biological function. We developed a system to probe mechanisms of secondary structure folding and exchange directly in vivo using self-cleavage to monitor competition between mutually exclusive structures that promote or inhibit ribozyme assembly. In previous work, upstream structures were more effective than downstream structures in blocking ribozyme assembly during transcription in vitro, consistent with a sequential folding mechanism. However, upstream and downstream structures blocked ribozyme assembly equally well in vivo, suggesting that intracellular folding outcomes reflect thermodynamic equilibration or that annealing of contiguous sequences is favored kinetically. We have extended these studies to learn when, if ever, thermodynamic stability becomes an impediment to rapid equilibration among alternative RNA structures in vivo. We find that a narrow thermodynamic threshold determines whether kinetics or thermodynamics govern RNA folding outcomes in vivo. mRNA secondary structures fold sequentially in vivo, but exchange between adjacent secondary structures is much faster in vivo than it is in vitro. Previous work showed that simple base-paired RNA helices dissociate at similar rates in vivo and in vitro so exchange between adjacent structures must occur through a different mechanism, one that likely involves facilitation of branch migration by proteins associated with nascent transcripts.

  16. THE DEVELOPMENT OF NETWORK INTERACTIONS BETWEEN PUBLIC AND STATE STRUCTURES IN SECONDARY EDUCATION MANAGEMENT

    Directory of Open Access Journals (Sweden)

    Oleksandr V. Pastovenskyi

    2014-06-01

    Full Text Available The developmental tendencies of secondary education management system are considered in the article. It was established, that an effective management of the educational systems can be attained on the basis of delegation of administrative functions from state to self-governmental, educational and public structures. The conclusion was made that the network interactions of the community management structures with vertical state structures being constructed from top to bottom, and the vertical of self-governing bodies being built from the bottom to the top, will provide the educational system with stability as well as the opportunities for effective development. It was emphasized, that modern cloud technology output network interactions of state, self-governmental, educational and public structures in the secondary education management to a new level.

  17. Secondary structure of prokaryotic 5S ribosomal ribonucleic acids: a study with ribonucleases

    DEFF Research Database (Denmark)

    Douthwaite, S; Garrett, R A

    1981-01-01

    , we were able to distinguish between primary and secondary cutting positions and also to establish the relative degree of cutting. The data reveal the predicted similarities of the higher order structure in the two RNAs but also demonstrate a few significant differences. The data also provide direct...

  18. Temperature scanning FTIR analysis of secondary structures of proteins embedded in amorphous sugar matrix.

    Science.gov (United States)

    Imamura, Koreyoshi; Ohyama, Ken-Ichi; Yokoyama, Toru; Maruyama, Yoshinobu; Kazuhiro, Nakanishi

    2009-09-01

    Heat-induced changes in secondary structures of five proteins (bovine serum albumin, BSA; human serum albumin, HSA; myoglobin; ribonuclease A, RNase A; and, beta-lactoglobulin, beta-Lg) in an amorphous sugar matrix were analyzed by temperature-scanning Fourier transform infrared spectroscopy to elucidate the mechanism of heat-induced conformational change of solid-phase proteins. Three sugars, trehalose, maltose, and dextran (MW 6000), were used. Loss of alpha-helices due to increasing temperature was observed for BSA, HSA, and myoglobin, which are rich in alpha-helices. RNase A showed a marked decrease in predominant secondary structural components (beta-sheet) with increasing temperature. However, no noticeable changes in the content of secondary structures, except for a slight loss of alpha-helices, were observed for beta-Lg, which is also beta-sheet-rich. These heat-induced conformational changes were significant at temperatures above the glass transition temperature. The heat-induced conformational change in BSA dried with sugar appeared time-independent and was clearly different from that due to dehydration and from the thermal conformational change for a solution of BSA. In particular, differences in secondary structural components that increased due to loss of alpha-helices were noted.

  19. Amide I'-II' 2D IR spectroscopy provides enhanced protein secondary structural sensitivity.

    Science.gov (United States)

    Deflores, Lauren P; Ganim, Ziad; Nicodemus, Rebecca A; Tokmakoff, Andrei

    2009-03-11

    We demonstrate how multimode 2D IR spectroscopy of the protein amide I' and II' vibrations can be used to distinguish protein secondary structure. Polarization-dependent amide I'-II' 2D IR experiments on poly-l-lysine in the beta-sheet, alpha-helix, and random coil conformations show that a combination of amide I' and II' diagonal and cross peaks can effectively distinguish between secondary structural content, where amide I' infrared spectroscopy alone cannot. The enhanced sensitivity arises from frequency and amplitude correlations between amide II' and amide I' spectra that reflect the symmetry of secondary structures. 2D IR surfaces are used to parametrize an excitonic model for the amide I'-II' manifold suitable to predict protein amide I'-II' spectra. This model reveals that the dominant vibrational interaction contributing to this sensitivity is a combination of negative amide II'-II' through-bond coupling and amide I'-II' coupling within the peptide unit. The empirically determined amide II'-II' couplings do not significantly vary with secondary structure: -8.5 cm(-1) for the beta sheet, -8.7 cm(-1) for the alpha helix, and -5 cm(-1) for the coil.

  20. The Turn of the Screw: An Exercise in Protein Secondary Structure

    Science.gov (United States)

    Pikaart, Michael

    2011-01-01

    An exercise using simple paper strips to illustrate protein helical and sheet secondary structures is presented. Drawing on the rich historical context of the use of physical models in protein biochemistry by early practitioners, in particular Linus Pauling, the purpose of this activity is to cultivate in students a hands-on, intuitive sense of…

  1. Use of tiling array data and RNA secondary structure predictions to identify noncoding RNA genes

    DEFF Research Database (Denmark)

    Weile, Christian; Gardner, Paul P; Hedegaard, Mads M

    2007-01-01

    BACKGROUND: Within the last decade a large number of noncoding RNA genes have been identified, but this may only be the tip of the iceberg. Using comparative genomics a large number of sequences that have signals concordant with conserved RNA secondary structures have been discovered in the human...

  2. Instruction in text-structure as a determinant of senior secondary ...

    African Journals Online (AJOL)

    The study determined the effectiveness of instruction in text-structure on achievement of students in English narrative text. The pretest-posttest control group quasi experimental design was adopted for the study. The participants were 120 students in intact classes from four purposively selected senior secondary schools in ...

  3. Full-scale performance assessment of aircraft secondary sandwich structure using thermoelastic stress analysis

    OpenAIRE

    Crump, D.A.; Dulieu-Barton, J.M.; Savage, J

    2009-01-01

    The use of resin film infusion (RFI) has been proven to reduce the cost of production of aircraft secondary sandwich structure. In this paper thermoelastic stress analysis (TSA) is used to assess the performance of full scale aircraft sandwich structure panels produced using both the conventional autoclave process and RFI. Finite element (FE) models of both panel types are developed and TSA is used to validate the models.

  4. Coherent two-dimensional infrared spectroscopy: Quantitative analysis of protein secondary structure in solution

    OpenAIRE

    Baiz, Carlos R.; Peng, Chunte; Reppert, Michael Earl; Jones, Kevin C; Tokmakoff, Andrei

    2011-01-01

    We present a method to quantitatively determine the secondary structure composition of globular proteins using coherent two-dimensional infrared (2DIR) spectroscopy of backbone amide I vibrations (1550–1720 cm−1). Sixteen proteins with known crystal structures were used to construct a library of 2DIR spectra, and the fraction of residues in α-helix, β-sheet, and unassigned conformations was determined by singular value decomposition (SVD) of the measured two-dimensional spectra. The method wa...

  5. Secondary flow structure in a model curved artery: 3D morphology and circulation budget analysis

    Science.gov (United States)

    Bulusu, Kartik V.; Plesniak, Michael W.

    2015-11-01

    In this study, we examined the rate of change of circulation within control regions encompassing the large-scale vortical structures associated with secondary flows, i.e. deformed Dean-, Lyne- and Wall-type (D-L-W) vortices at planar cross-sections in a 180° curved artery model (curvature ratio, 1/7). Magnetic resonance velocimetry (MRV) and particle image velocimetry (PIV) experiments were performed independently, under the same physiological inflow conditions (Womersley number, 4.2) and using Newtonian blood-analog fluids. The MRV-technique performed at Stanford University produced phase-averaged, three-dimensional velocity fields. Secondary flow field comparisons of MRV-data to PIV-data at various cross-sectional planes and inflow phases were made. A wavelet-decomposition-based approach was implemented to characterize various secondary flow morphologies. We hypothesize that the persistence and decay of arterial secondary flow vortices is intrinsically related to the influence of the out-of-plane flow, tilting, in-plane convection and diffusion-related factors within the control regions. Evaluation of these factors will elucidate secondary flow structures in arterial hemodynamics. Supported by the National Science Foundation under Grant Number CBET-0828903, and GW Center for Biomimetics and Bioinspired Engineering (COBRE). The MRV data were acquired at Stanford University in collaboration with Christopher Elkins and John Eaton.

  6. The Relationship between Secondary Structure and Biodegradation Behavior of Silk Fibroin Scaffolds

    Directory of Open Access Journals (Sweden)

    Yongpei Hu

    2012-01-01

    Full Text Available Silk fibroin has a unique and useful combination of properties, including good biocompatibility and excellent mechanical performance. These features provided early clues to the utility of regenerated silk fibroin as a scaffold/matrix for tissue engineering. The silk fibroin scaffolds used for tissue engineering should degrade at a rate that matches the tissue growth rate. The relationship between secondary structure and biodegradation behavior of silk fibroin scaffolds was investigated in this study. Scaffolds with different secondary structure were prepared by controlling the freezing temperature and by treatment with carbodiimide or ethanol. The quantitative proportions of each secondary structure were obtained by Fourier transform infrared spectroscopy (FTIR, and each sample was then degraded in vitro with collagenase IA for 18 days. The results show that a high content of β-sheet structure leads to a low degradation rate. The random coil region in the silk fibroin material is degraded, whereas the crystal region remains stable and the amount of β-sheet structure increases during incubation. The results demonstrate that it is possible to control the degradation rate of a silk fibroin scaffold by controlling the content of β-sheet structure.

  7. Knowledge base and neural network approach for protein secondary structure prediction.

    Science.gov (United States)

    Patel, Maulika S; Mazumdar, Himanshu S

    2014-11-21

    Protein structure prediction is of great relevance given the abundant genomic and proteomic data generated by the genome sequencing projects. Protein secondary structure prediction is addressed as a sub task in determining the protein tertiary structure and function. In this paper, a novel algorithm, KB-PROSSP-NN, which is a combination of knowledge base and modeling of the exceptions in the knowledge base using neural networks for protein secondary structure prediction (PSSP), is proposed. The knowledge base is derived from a proteomic sequence-structure database and consists of the statistics of association between the 5-residue words and corresponding secondary structure. The predicted results obtained using knowledge base are refined with a Backpropogation neural network algorithm. Neural net models the exceptions of the knowledge base. The Q3 accuracy of 90% and 82% is achieved on the RS126 and CB396 test sets respectively which suggest improvement over existing state of art methods. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Searching for three-dimensional secondary structural patterns in proteins with ProSMoS.

    Science.gov (United States)

    Shi, Shuoyong; Zhong, Yi; Majumdar, Indraneel; Sri Krishna, S; Grishin, Nick V

    2007-06-01

    Many evolutionarily distant, but functionally meaningful links between proteins come to light through comparison of spatial structures. Most programs that assess structural similarity compare two proteins to each other and find regions in common between them. Structural classification experts look for a particular structural motif instead. Programs base similarity scores on superposition or closeness of either Cartesian coordinates or inter-residue contacts. Experts pay more attention to the general orientation of the main chain and mutual spatial arrangement of secondary structural elements. There is a need for a computational tool to find proteins with the same secondary structures, topological connections and spatial architecture, regardless of subtle differences in 3D coordinates. We developed ProSMoS--a Protein Structure Motif Search program that emulates an expert. Starting from a spatial structure, the program uses previously delineated secondary structural elements. A meta-matrix of interactions between the elements (parallel or antiparallel) minding handedness of connections (left or right) and other features (e.g. element lengths and hydrogen bonds) is constructed prior to or during the searches. All structures are reduced to such meta-matrices that contain just enough information to define a protein fold, but this definition remains very general and deviations in 3D coordinates are tolerated. User supplies a meta-matrix for a structural motif of interest, and ProSMoS finds all proteins in the protein data bank (PDB) that match the meta-matrix. ProSMoS performance is compared to other programs and is illustrated on a beta-Grasp motif. A brief analysis of all beta-Grasp-containing proteins is presented. Program availability: ProSMoS is freely available for non-commercial use from ftp://iole.swmed.edu/pub/ProSMoS.

  9. Intra-specific differentiation of fungal endosymbiont Alternaria longissima CLB44 using RNA secondary structure analysis and their anti-infective potential.

    Science.gov (United States)

    Rao, H C Yashavantha; Satish, Sreedharamurthy

    2016-08-01

    New antimicrobial agents derived from endosymbio-tic fungi with unique and targeted mode of action are crucially rudimentary to combat multidrug-resistant infections. Most of the fungi isolated as endosymbionts show close morphological feature resemblance to plant pathogenic or free-living forms, and it is difficult to differentiate these different lifestyles. A fungal endosymbiont strain CLB44 was isolated from Combretum latifolium Blume (Combretaceae). CLB44 was then identified as Alternaria longissima based on morphological and internal transcribed spacer (ITS) intervening 5.8S rRNA gene sequence analysis. ITS2 RNA secondary structure analysis was carried out using mfold server with temperature 37 °C, and anti-infective potential was determined by MIC and disk diffusion methods. ITS2 RNA secondary structure analysis clearly distinguished endosymbiotic A. longissima CLB44 from free-living and pathogenic A. longissima members in the same monophyletic clade. Secondary metabolites produced effectively inhibited Pseudomonas aeruginosa (25 μg/ml), Escherichia coli (25 μg/ml), methicillin-resistant Staphylococcus aureus (50 μg/ml), Candida albicans (100 μg/ml), and other human pathogens. This study emerges as an innovative finding that explores newly revealed ITS2 RNAs that may be an insight as new markers for refining phylogenetic relations and to distinguish fungal endosymbionts with other free-living or pathogenic forms. A. longissima CLB44, in the emerging field of endosymbionts, will pave the way to a novel avenue in drug discovery to combat multidrug-resistant infections. The sequence data of this fungus is deposited in GenBank under the accession no. KU310611.

  10. Secondary structure-based analysis of mouse brain small RNA sequences obtained by using next-generation sequencing.

    Science.gov (United States)

    Kiyosawa, Hidenori; Okumura, Akio; Okui, Saya; Ushida, Chisato; Kawai, Gota

    2015-08-01

    In order to find novel structured small RNAs, next-generation sequencing was applied to small RNA fractions with lengths ranging from 40 to 140 nt and secondary structure-based clustering was performed. Sequences of structured RNAs were effectively clustered and analyzed by secondary structure. Although more than 99% of the obtained sequences were known RNAs, 16 candidate mouse structured small non-coding RNAs (MsncRs) were isolated. Based on these results, the merits of secondary structure-based analysis are discussed. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. SecStAnT: secondary structure analysis tool for data selection, statistics and models building.

    Science.gov (United States)

    Maccari, Giuseppe; Spampinato, Giulia L B; Tozzini, Valentina

    2014-03-01

    Atomistic or coarse grained (CG) potentials derived from statistical distributions of internal variables have recently become popular due to the need of simplified interactions for reaching larger scales in simulations or more efficient conformational space sampling. However, the process of parameterization of accurate and predictive statistics-based force fields requires a huge amount of work and is prone to the introduction of bias and errors. This article introduces SecStAnT, a software for the creation and analysis of protein structural datasets with user-defined primary/secondary structure composition, with a particular focus on the CG representation. In addition, the possibility of managing different resolutions and the primary/secondary structure selectivity allow addressing the mapping-backmapping of atomistic to CG representation and study the secondary to primary structure relations. Sample datasets and distributions are reported, including interpretation of structural features. SecStAnT is available free of charge at secstant.sourceforge.net/. Source code is freely available on request, implemented in Java and supported on Linux, MS Windows and OSX.

  12. Rigidity of poly-L-glutamic acid scaffolds: Influence of secondary and supramolecular structure

    Energy Technology Data Exchange (ETDEWEB)

    Perticaroli, Stefania [ORNL; Ehlers, Georg [ORNL; Feygenson, Mikhail [ORNL; Sokolov, Alexei P [ORNL

    2015-01-01

    Poly-L-glutamic acid (PGA) is a widely used biomaterial, with applications ranging from drug delivery and biological glues to food products and as a tissue engineering scaffold. A biodegradable material with flexible conjugation functional groups, tunable secondary structure, and mechanical properties, PGA has potential as a tunable matrix material in mechanobiology. Some recent studies in proteins connecting dynamics, nanometer length scale rigidity, and secondary structure suggest a new point of view from which to analyze and develop this promising material. Our paper characterizes the structure, topology, and rigidity properties of PGA prepared with different molecular weights and secondary structures through various techniques including scanning electron microscopy, FTIR, light, and neutron scattering spectroscopy. On the length scale of a few nanometers, rigidity is determined by hydrogen bonding interactions in the presence of neutral species and by electrostatic interactions when the polypeptide is negatively charged. Finally, when probed over hundreds of nanometers, the rigidity of these materials is modified by long range intermolecular interactions that are introduced by the supramolecular structure.

  13. Resurrection of an ancestral 5S rRNA.

    Science.gov (United States)

    Lu, Qing; Fox, George E

    2011-07-22

    In addition to providing phylogenetic relationships, tree making procedures such as parsimony and maximum likelihood can make specific predictions of actual historical sequences. Resurrection of such sequences can be used to understand early events in evolution. In the case of RNA, the nature of parsimony is such that when applied to multiple RNA sequences it typically predicts ancestral sequences that satisfy the base pairing constraints associated with secondary structure. The case for such sequences being actual ancestors is greatly improved, if they can be shown to be biologically functional. A unique common ancestral sequence of 28 Vibrio 5S ribosomal RNA sequences predicted by parsimony was resurrected and found to be functional in the context of the E. coli cellular environment. The functionality of various point variants and intermediates that were constructed as part of the resurrection were examined in detail. When separately introduced the changes at single stranded positions and individual double variants at base-paired positions were also viable. An additional double variant was examined at a different base-paired position and it was also valid. The results show that at least in the case of the 5S rRNAs considered here, ancestors predicted by parsimony are likely to be realistic when the prediction is not overly influenced by single outliers. It is especially noteworthy that the phenotype of the predicted ancestors could be anticipated as a cumulative consequence of the phenotypes of the individual variants that comprised them. Thus, point mutation data is potentially useful in evaluating the reasonableness of ancestral sequences predicted by parsimony or other methods. The results also suggest that in the absence of significant tertiary structure constraints double variants that preserve pairing in stem regions will typically be accepted. Overall, the results suggest that it will be feasible to resurrect additional meaningful 5S rRNA ancestors as well

  14. Small-angle X-ray scattering: a bridge between RNA secondary structures and three-dimensional topological structures

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Xianyang [National Inst. of Health (NIH), Bethesda, MD (United States). National Cancer Inst., NCI Small Angle X-ray Scattering Core Facility; Stagno, Jason R. [National Inst. of Health (NIH), Bethesda, MD (United States). National Cancer Inst., Protein-Nucleic Acid Interaction Section, Structural Biophysics Lab.; Bhandari, Yuba R. [National Inst. of Health (NIH), Bethesda, MD (United States). National Cancer Inst., Protein-Nucleic Acid Interaction Section, Structural Biophysics Lab.; Zuo, Xiaobing [Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS); Wang, Yun-Xing [National Inst. of Health (NIH), Bethesda, MD (United States). National Cancer Inst., NCI Small Angle X-ray Scattering Core Facility; National Inst. of Health (NIH), Bethesda, MD (United States). National Cancer Inst., Protein-Nucleic Acid Interaction Section, Structural Biophysics Lab.

    2015-02-01

    Whereas the structures of small to medium-sized well folded RNA molecules often can be determined by either X-ray crystallography or NMR spectroscopy, obtaining structural information for large RNAs using experimental, computational, or combined approaches remains a major interest and challenge. RNA is very sensitive to small-angle X-ray scattering (SAXS) due to high electron density along phosphate-sugar backbones, whose scattering contribution dominates SAXS intensity. For this reason, SAXS is particularly useful in obtaining global RNA structural information that outlines backbone topologies and, therefore, molecular envelopes. Such information is extremely valuable in bridging the gap between the secondary structures and three-dimensional topological structures of RNAmolecules, particularly those that have proven difficult to study using other structuredetermination methods. Here we review published results of RNA topological structures derived from SAXS data or in combination with other experimental data, as well as details on RNA sample preparation for SAXS experiments.

  15. A contribution to understanding the structure of amphivasal secondary bundles in monocotyledons

    Directory of Open Access Journals (Sweden)

    Joanna Jura-Morawiec

    2014-04-01

    Full Text Available Secondary growth of monocotyledonous plants is connected with the activity of the monocot cambium that accumulates most of the derivatives inner to the cambial cylinder. These derivatives differentiate into (a secondary bundles with the amphivasal arrangement, i.e. xylem composed of tracheids surrounds the phloem cells and (b the parenchymatous secondary conjunctive tissue in which the bundles are embedded. The amphivasal secondary bundles differ in the arrangement of xylem cells as visible on single cross sections through the secondary body of the monocots. Apart from the bundles with typical ring of tracheids also the bundles where tracheids do not quite surround the phloem are present. We aimed to elucidate the cross sectional anatomy of the amphivasal secondary bundles with the use of the serial sectioning method which allowed us to follow very precisely the bundle structure along its length. The studies were carried out with the samples of secondary tissues collected from the stem of Dracaena draco L. growing in the greenhouses of the Polish Academy of Sciences Botanical Garden – CBDC in Powsin and the Adam Mickiewicz University Botanical Garden. The material was fixed in a mixture of glycerol and ethanol (1:1; v/v, dehydrated stepwise with graded ethanol series and finally embedded in epon resin. Afterwards, the material was sectioned with microtome into continuous series of thin (3 μm sections, stained with PAS/toluidine blue and examined under the light microscope. The results, described in details in Jura‑Morawiec & Wiland-Szymańska (2014, revealed novel facts about tracheids arrangement. Each amphivasal bundle is composed of sectors where tracheids form a ring as well as of such where tracheids are separated by vascular parenchyma cells. We hypothesize that strands of vascular parenchyma cells locally separating the tracheids enable radial transport of assimilates from sieve elements of the bundle towards the sink tissues, e

  16. Archaea box C/D enzymes methylate two distinct substrate rRNA sequences with different efficiency.

    Science.gov (United States)

    Graziadei, Andrea; Masiewicz, Pawel; Lapinaite, Audrone; Carlomagno, Teresa

    2016-05-01

    RNA modifications confer complexity to the 4-nucleotide polymer; nevertheless, their exact function is mostly unknown. rRNA 2'-O-ribose methylation concentrates to ribosome functional sites and is important for ribosome biogenesis. The methyl group is transferred to rRNA by the box C/D RNPs: The rRNA sequence to be methylated is recognized by a complementary sequence on the guide RNA, which is part of the enzyme. In contrast to their eukaryotic homologs, archaeal box C/D enzymes can be assembled in vitro and are used to study the mechanism of 2'-O-ribose methylation. In Archaea, each guide RNA directs methylation to two distinct rRNA sequences, posing the question whether this dual architecture of the enzyme has a regulatory role. Here we use methylation assays and low-resolution structural analysis with small-angle X-ray scattering to study the methylation reaction guided by the sR26 guide RNA fromPyrococcus furiosus We find that the methylation efficacy at sites D and D' differ substantially, with substrate D' turning over more efficiently than substrate D. This observation correlates well with structural data: The scattering profile of the box C/D RNP half-loaded with substrate D' is similar to that of the holo complex, which has the highest activity. Unexpectedly, the guide RNA secondary structure is not responsible for the functional difference at the D and D' sites. Instead, this difference is recapitulated by the nature of the first base pair of the guide-substrate duplex. We suggest that substrate turnover may occur through a zip mechanism that initiates at the 5'-end of the product. © 2016 Graziadei et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  17. Fragmentary 5S rRNA gene in the human mitochondrial genome

    Energy Technology Data Exchange (ETDEWEB)

    Nierlich, D.P.

    1982-02-01

    The human mitochondrial genoma contains a 23-nucleodtide sequence that is homologous to a part of the 5S rRNA's of bacteria. This homology, the structure of the likely transcript, and the location of the sequence relative to the mitochondrial rRNA genes suggest that the sequence represents a fragmentary 5S rRNA gene.

  18. Fast learning optimized prediction methodology (FLOPRED) for protein secondary structure prediction.

    Science.gov (United States)

    Saraswathi, S; Fernández-Martínez, J L; Kolinski, A; Jernigan, R L; Kloczkowski, A

    2012-09-01

    Computational methods are rapidly gaining importance in the field of structural biology, mostly due to the explosive progress in genome sequencing projects and the large disparity between the number of sequences and the number of structures. There has been an exponential growth in the number of available protein sequences and a slower growth in the number of structures. There is therefore an urgent need to develop computational methods to predict structures and identify their functions from the sequence. Developing methods that will satisfy these needs both efficiently and accurately is of paramount importance for advances in many biomedical fields, including drug development and discovery of biomarkers. A novel method called fast learning optimized prediction methodology (FLOPRED) is proposed for predicting protein secondary structure, using knowledge-based potentials combined with structure information from the CATH database. A neural network-based extreme learning machine (ELM) and advanced particle swarm optimization (PSO) are used with this data that yield better and faster convergence to produce more accurate results. Protein secondary structures are predicted reliably, more efficiently and more accurately using FLOPRED. These techniques yield superior classification of secondary structure elements, with a training accuracy ranging between 83 % and 87 % over a widerange of hidden neurons and a cross-validated testing accuracy ranging between 81 % and 84 % and a segment overlap (SOV) score of 78 % that are obtained with different sets of proteins. These results are comparable to other recently published studies, but are obtained with greater efficiencies, in terms of time and cost.

  19. Molecular phylogenetics of the spider family Micropholcommatidae (Arachnida: Araneae) using nuclear rRNA genes (18S and 28S).

    Science.gov (United States)

    Rix, Michael G; Harvey, Mark S; Roberts, J Dale

    2008-03-01

    The spider family Micropholcommatidae is an enigmatic taxon of uncertain limits and uncertain affinities. Various phylogenetic hypotheses have been proposed for the family, but these hypotheses have never been tested with a robust phylogenetic analysis. The existence of similar Australasian and New World taxa, the possibility of morphological convergence associated with extreme 'smallness', and the apparent paucity of synapomorphic morphological characters, have all clouded generic relationships in this group. We used fragments from two nuclear ribosomal RNA genes (18S and 28S) to test the monophyly and phylogenetic position of the Micropholcommatidae. The analyses incorporated 50 ingroup spider species, including 23 micropholcommatid species and representatives from 14 other spider families. Ribosomal RNA secondary structures were inferred for the V3-V5 region of the 18S rRNA gene, and Domain II of the 28S rRNA gene of Hickmania troglodytes [Higgins, E.T., Petterd, W.F., 1883. Description of a new cave-inhabiting spider, together with notes on mammalian remains from a recently discovered cave in the Chudleigh district. Pap. Proc. R. Soc. Tasman. 1882, 191-192]. These secondary structures were used to guide multiple sequence alignments, and determine the position and nature of indels in different taxa. Secondary structure information was also incorporated into a structurally partitioned rRNA analysis in MrBayes Version 3.1.2, using a doublet model of nucleotide substitution. This structurally partitioned rRNA analysis provided a less resolved but more conservative and informative estimate of phylogeny than an otherwise identical, unpartitioned rDNA analysis. With the exception of the Chilean species Teutoniella cekalovici [Platnick, N.I., Forster, R.R., 1986. On Teutoniella, an American genus of the spider family Micropholcommatidae (Araneae, Palpimanoidea). Am. Mus. Novit. 2854, 1-9], the family Micropholcommatidae was found to be monophyletic with three

  20. Kinetics of secondary structure recovery during the refolding of reduced hen egg white lysozyme.

    Science.gov (United States)

    Roux, P; Delepierre, M; Goldberg, M E; Chaffotte, A F

    1997-10-03

    We have shown previously that, in less than 4 ms, the unfolded/oxidized hen lysozyme recovered its native secondary structure, while the reduced protein remained fully unfolded. To investigate the role played by disulfide bridges in the acquisition of the secondary structure at later stages of the renaturation/oxidation, the complete refolding of reduced lysozyme was studied. This was done in a renaturation buffer containing 0.5 M guanidinium chloride, 60 microM oxidized glutathione, and 20 microM reduced dithiothreitol, in which the aggregation of lysozyme was minimized and where a renaturation yield of 80% was obtained. The refolded protein could not be distinguished from the native lysozyme by activity, compactness, stability, and several spectroscopic measurements. The kinetics of renaturation were then studied by following the reactivation and the changes in fluorescence and circular dichroism signals. When bi- or triphasic sequential models were fitted to the experimental data, the first two phases had the same calculated rate constants for all the signals showing that, within the time resolution of these experiments, the folding/oxidation of hen lysozyme is highly cooperative, with the secondary structure, the tertiary structure, and the integrity of the active site appearing simultaneously.

  1. Self-Efficacy, School Resources, Job Stressors and Burnout among Spanish Primary and Secondary School Teachers: A Structural Equation Approach

    Science.gov (United States)

    Betoret, Fernando Domenech

    2009-01-01

    This study examines the relationship between school resources, teacher self-efficacy, potential multi-level stressors and teacher burnout using structural equation modelling. The causal structure for primary and secondary school teachers was also examined. The sample was composed of 724 primary and secondary Spanish school teachers. The changes…

  2. TurboFold: Iterative probabilistic estimation of secondary structures for multiple RNA sequences

    Directory of Open Access Journals (Sweden)

    Sharma Gaurav

    2011-04-01

    Full Text Available Abstract Background The prediction of secondary structure, i.e. the set of canonical base pairs between nucleotides, is a first step in developing an understanding of the function of an RNA sequence. The most accurate computational methods predict conserved structures for a set of homologous RNA sequences. These methods usually suffer from high computational complexity. In this paper, TurboFold, a novel and efficient method for secondary structure prediction for multiple RNA sequences, is presented. Results TurboFold takes, as input, a set of homologous RNA sequences and outputs estimates of the base pairing probabilities for each sequence. The base pairing probabilities for a sequence are estimated by combining intrinsic information, derived from the sequence itself via the nearest neighbor thermodynamic model, with extrinsic information, derived from the other sequences in the input set. For a given sequence, the extrinsic information is computed by using pairwise-sequence-alignment-based probabilities for co-incidence with each of the other sequences, along with estimated base pairing probabilities, from the previous iteration, for the other sequences. The extrinsic information is introduced as free energy modifications for base pairing in a partition function computation based on the nearest neighbor thermodynamic model. This process yields updated estimates of base pairing probability. The updated base pairing probabilities in turn are used to recompute extrinsic information, resulting in the overall iterative estimation procedure that defines TurboFold. TurboFold is benchmarked on a number of ncRNA datasets and compared against alternative secondary structure prediction methods. The iterative procedure in TurboFold is shown to improve estimates of base pairing probability with each iteration, though only small gains are obtained beyond three iterations. Secondary structures composed of base pairs with estimated probabilities higher than a

  3. Protein Phosphorylation and Mineral Binding Affect the Secondary Structure of the Leucine-Rich Amelogenin Peptide

    Directory of Open Access Journals (Sweden)

    Hajime Yamazaki

    2017-06-01

    Full Text Available Previously, we have shown that serine-16 phosphorylation in native full-length porcine amelogenin (P173 and the Leucine-Rich Amelogenin Peptide (LRAP(+P, an alternative amelogenin splice product, affects protein assembly and mineralization in vitro. Notably, P173 and LRAP(+P stabilize amorphous calcium phosphate (ACP and inhibit hydroxyapatite (HA formation, while non-phosphorylated counterparts (rP172, LRAP(−P guide the growth of ordered bundles of HA crystals. Based on these findings, we hypothesize that the phosphorylation of full-length amelogenin and LRAP induces conformational changes that critically affect its capacity to interact with forming calcium phosphate mineral phases. To test this hypothesis, we have utilized Fourier transform infrared spectroscopy (FTIR to determine the secondary structure of LRAP(−P and LRAP(+P in the absence/presence of calcium and selected mineral phases relevant to amelogenesis; i.e., hydroxyapatite (HA: an enamel crystal prototype and (ACP: an enamel crystal precursor phase. Aqueous solutions of LRAP(−P or LRAP(+P were prepared with or without 7.5 mM of CaCl2 at pH 7.4. FTIR spectra of each solution were obtained using attenuated total reflectance, and amide-I peaks were analyzed to provide secondary structure information. Secondary structures of LRAP(+P and LRAP(−P were similarly assessed following incubation with suspensions of HA and pyrophosphate-stabilized ACP. Amide I spectra of LRAP(−P and LRAP(+P were found to be distinct from each other in all cases. Spectra analyses showed that LRAP(−P is comprised mostly of random coil and β-sheet, while LRAP(+P exhibits more β-sheet and α-helix with little random coil. With added Ca, the random coil content increased in LRAP(−P, while LRAP(+P exhibited a decrease in α-helix components. Incubation of LRAP(−P with HA or ACP resulted in comparable increases in β-sheet structure. Notably, however, LRAP(+P secondary structure was more affected by

  4. Molecular characterization of pouched amphistome parasites (Trematoda: Gastrothylacidae) using ribosomal ITS2 sequence and secondary structures.

    Science.gov (United States)

    Ghatani, S; Shylla, J A; Tandon, V; Chatterjee, A; Roy, B

    2012-03-01

    Members of the family Gastrothylacidae (Trematoda: Digenea: Paramphistomata) are parasitic in ruminants throughout Africa and Asia. In north-east India, five species of pouched amphistomes, namely Fischoederius cobboldi, F. elongatus, Gastrothylax crumenifer, Carmyerius spatiosus and Velasquezotrema tripurensis, belonging to this family have been reported so far. In the present study, the molecular phylogeny of these five gastrothylacid species is derived using the second internal transcribed spacer (ITS2) sequence and secondary structure analyses. ITS2 sequence analysis was carried out to see the occurrence of interspecific variations among the species. Phylogenetic analyses were performed for primary sequence data alone as well as the combined sequence-structure information using neighbour-joining and Bayesian approaches. The sequence analysis revealed that there exist considerable interspecific variations among the various gastrothylacid fluke species. In contrast, the inferred secondary structures for the five species using minimum free energy modelling showed structural identities, in conformity with the core four-helix domain structure that has been recently identified as common to almost all eukaryotic taxa. The phylogenetic tree reconstructed using combined sequence-structure data showed a better resolution, as compared to the one using sequence data alone, with the gastrothylacid species forming a monophyletic group that is well separated from members of the other family, Paramphistomidae, of the amphistomid flukes group. The study provides the molecular characterization based on primary sequence data of the rDNA ITS2 region of the gastrothylacid amphistome flukes. Results also demonstrate the phylogenetic utility of the ITS2 sequence-secondary structure data for inferences at higher taxonomic levels.

  5. Determination of the Secondary Structure of the king Cobra Neurotoxin CM-11.

    Science.gov (United States)

    Pang, Yu-Xi; Liu, Wei-Dong; Liu, Ai-Zhuo; Pei, Feng-Kui

    1997-01-01

    The king cobra neurotoxin CM-11 is a small protein with 72 amino acid residues. After its complete assignments of (1)H-NMR resonance's were obtained using various 2D-NMR technologies, including DQF-COSY, clean-TOCSY and NOESY, the secondary structure was analysed by studying the various NOEs extracted from the NOESY spectra and the distribution of chemical shifts. The secondary structure was finally determined by MCD as follows: a triple-strand antiparallel beta sheet with I20-W26, R37-A43 and V53-S59 as its beta strands, a short alpha helix formed by W30-G35 and four turns formed by P7-K1O, C14-G17, K50-V53 and D61-N64.

  6. Interplay between desolvation and secondary structure in mediating cosolvent and temperature induced alpha-synuclein aggregation

    OpenAIRE

    Anderson, V. L.; Webb, W W; Eliezer, D.

    2012-01-01

    Both increased temperature and moderate concentrations of fluorinated alcohols enhance aggregation of the Parkinson’s disease-associated protein α–synuclein (αS). Here, we investigate the secondary structural rearrangements induced by heating and trifluoroethanol (TFE). At low TFE concentrations, CD spectra feature a negative peak characteristic of disordered polypeptides near 200 nm and a slight shoulder around 220 nm suggesting some polyproline-II content. Upon heating, these peaks weaken, ...

  7. Effect of pressure on secondary structure of proteins under ultra high pressure liquid chromatographic conditions.

    Science.gov (United States)

    Makarov, Alexey; LoBrutto, Rosario; Karpinski, Paul

    2013-11-29

    There are several spectroscopic techniques such as IR and CD, that allow for analyzing protein secondary structure in solution. However, a majority of these techniques require using purified protein, concentrated enough in the solution, to produce a relevant spectrum. Fundamental principles for the usage of reversed-phase ultra high pressure liquid chromatography (UHPLC) as an alternative technique to study protein secondary structures in solution were investigated. Several "model" proteins, as well as several small ionizable and neutral molecules, were used for these studies. The studies were conducted with UHPLC in isocratic mode, using premixed mobile phases at constant flow rate and temperature. The pressure was modified by a backpressure regulator from about 6000psi to about 12,000psi. It was found that when using a mobile phase composition at which proteins were fully denatured (loss of alpha-helix secondary structure), the retention factors of the proteins increased upon pressure increase in the same manner as non-proteins. When using a mobile phase composition in which proteins were not fully denatured, it was observed that the retention factors of the proteins displayed a much steeper (by one order of magnitude) increase in retention upon pressure increase. It was concluded that in a mobile phase in which the protein is not initially fully denatured, the increase of pressure may facilitate the folding back of the protein to its native state (alpha-helix secondary structure). The impact of different mobile phase compositions on the denaturation of the proteins was studied using CD (Circular Dichroism). Moreover, the effect of flow rate on retention of proteins and small molecules was studied at constant pressure on the different pore size silicas and the impact of internal frictional heating was evaluated. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. NNDB: the nearest neighbor parameter database for predicting stability of nucleic acid secondary structure.

    Science.gov (United States)

    Turner, Douglas H; Mathews, David H

    2010-01-01

    The Nearest Neighbor Database (NNDB, http://rna.urmc.rochester.edu/NNDB) is a web-based resource for disseminating parameter sets for predicting nucleic acid secondary structure stabilities. For each set of parameters, the database includes the set of rules with descriptive text, sequence-dependent parameters in plain text and html, literature references to experiments and usage tutorials. The initial release covers parameters for predicting RNA folding free energy and enthalpy changes.

  9. NNDB: the nearest neighbor parameter database for predicting stability of nucleic acid secondary structure

    OpenAIRE

    Turner, Douglas H.; David H Mathews

    2009-01-01

    The Nearest Neighbor Database (NNDB, http://rna.urmc.rochester.edu/NNDB) is a web-based resource for disseminating parameter sets for predicting nucleic acid secondary structure stabilities. For each set of parameters, the database includes the set of rules with descriptive text, sequence-dependent parameters in plain text and html, literature references to experiments and usage tutorials. The initial release covers parameters for predicting RNA folding free energy and enthalpy changes.

  10. Relationship between hydrophobic interactions and secondary structure stability for Trpzip beta-hairpin peptides.

    Science.gov (United States)

    Takekiyo, Takahiro; Wu, Ling; Yoshimura, Yukihiro; Shimizu, Akio; Keiderling, Timothy A

    2009-02-24

    The temperature-induced beta-hairpin stabilities of selected mutations of the Trpzip1 peptide, SWTWEGNKWTWK (WWWW), have been investigated by electronic circular dichroism (CD), Raman, and FT-IR spectroscopies. The tryptophan (Trp) residues in the original Trpzip1 sequence were systematically substituted with tyrosine (Tyr) in different positions to test the impact of Trp interactions on the beta-hairpin structure and stability. The CD intensity at approximately 228 nm, which arises from Trp-Trp interactions (tertiary structure), and the amide I' IR absorbance at approximately 1635 cm(-1) (secondary structure) have been measured over a range of temperatures to investigate the impact of Tyr substitution on beta-hairpin thermal stability in Trpzip peptides. Mutation from Trp to Tyr in the Trpzip1 sequence reduces the extent of beta-hairpin structure and monotonically decreases the beta-hairpin stability of Trpzip1 mutant peptides with an increasing number of Tyr substitutions. Substituted Trpzip peptides with just one pair of Trp-Trp interactions close to either the terminal residues (WYYW) or the turn (YWWY) have similar stabilities. Comparison of conformational transitions monitored by CD and IR reveals them to have multistate behavior in which the temperature-induced disruption of the Trp-Trp interaction (tertiary structure) occurs at a lower temperature than the unfolding of the secondary structure.

  11. [Peculiarities of secondary structure of serum albumin of some representatives of the animal kingdom].

    Science.gov (United States)

    Pekhymenko, G V; Kuchmerovskaia, T M

    2011-01-01

    Methods of infrared (IR) spectroscopy and circular dichroism (CD) are suitable techniques for detection of proteins structural changes. These methods were used for determinating peculiarities of the secondary structure of serum albumins in some representatives of two classes of reptiles: Horsfield's tortoise (Testudo horsfieldi), water snake (Natrix tessellata) and grass snake (Natrix natrix) and birds: domestic goose (Anser anser), domestic chicken (Gallus domesticus), domestic duck (Anas platyrhyncha) and dove colored (Columba livia). An analysis of IR spectra and spectra obtained by the method of CD of serum albumins of both classes representatives revealed that beta-folding structure and alpha-helical sections that form the alpha-conformation play an important role in conformational structure formation of polypeptide chain and also disordered sites of molecules of these proteins. It was observed that certain redistribution depending on animals species exists, in the formation of secondary structure of serum albumins of the investigated representatives of reptiles and birds classes between the content of beta-folding structure, alpha-helical sections and disordered sites in molecules of these proteins.

  12. SFESA: a web server for pairwise alignment refinement by secondary structure shifts.

    Science.gov (United States)

    Tong, Jing; Pei, Jimin; Grishin, Nick V

    2015-09-03

    Protein sequence alignment is essential for a variety of tasks such as homology modeling and active site prediction. Alignment errors remain the main cause of low-quality structure models. A bioinformatics tool to refine alignments is needed to make protein alignments more accurate. We developed the SFESA web server to refine pairwise protein sequence alignments. Compared to the previous version of SFESA, which required a set of 3D coordinates for a protein, the new server will search a sequence database for the closest homolog with an available 3D structure to be used as a template. For each alignment block defined by secondary structure elements in the template, SFESA evaluates alignment variants generated by local shifts and selects the best-scoring alignment variant. A scoring function that combines the sequence score of profile-profile comparison and the structure score of template-derived contact energy is used for evaluation of alignments. PROMALS pairwise alignments refined by SFESA are more accurate than those produced by current advanced alignment methods such as HHpred and CNFpred. In addition, SFESA also improves alignments generated by other software. SFESA is a web-based tool for alignment refinement, designed for researchers to compute, refine, and evaluate pairwise alignments with a combined sequence and structure scoring of alignment blocks. To our knowledge, the SFESA web server is the only tool that refines alignments by evaluating local shifts of secondary structure elements. The SFESA web server is available at http://prodata.swmed.edu/sfesa.

  13. The super-n-motifs model: a novel alignment-free approach for representing and comparing RNA secondary structures.

    Science.gov (United States)

    Glouzon, Jean-Pierre Séhi; Perreault, Jean-Pierre; Wang, Shengrui

    2017-04-15

    Comparing ribonucleic acid (RNA) secondary structures of arbitrary size uncovers structural patterns that can provide a better understanding of RNA functions. However, performing fast and accurate secondary structure comparisons is challenging when we take into account the RNA configuration (i.e. linear or circular), the presence of pseudoknot and G-quadruplex (G4) motifs and the increasing number of secondary structures generated by high-throughput probing techniques. To address this challenge, we propose the super-n-motifs model based on a latent analysis of enhanced motifs comprising not only basic motifs but also adjacency relations. The super-n-motifs model computes a vector representation of secondary structures as linear combinations of these motifs. We demonstrate the accuracy of our model for comparison of secondary structures from linear and circular RNA while also considering pseudoknot and G4 motifs. We show that the super-n-motifs representation effectively captures the most important structural features of secondary structures, as compared to other representations such as ordered tree, arc-annotated and string representations. Finally, we demonstrate the time efficiency of our model, which is alignment free and capable of performing large-scale comparisons of 10 000 secondary structures with an efficiency up to 4 orders of magnitude faster than existing approaches. The super-n-motifs model was implemented in C ++. Source code and Linux binary are freely available at http://jpsglouzon.github.io/supernmotifs/ . Shengrui.Wang@Usherbrooke.ca. Supplementary data are available at Bioinformatics o nline.

  14. CMD: A Database to Store the Bonding States of Cysteine Motifs with Secondary Structures.

    Science.gov (United States)

    Bostan, Hamed; Salim, Naomie; Hussein, Zeti Azura; Klappa, Peter; Shamsir, Mohd Shahir

    2012-01-01

    Computational approaches to the disulphide bonding state and its connectivity pattern prediction are based on various descriptors. One descriptor is the amino acid sequence motifs flanking the cysteine residue motifs. Despite the existence of disulphide bonding information in many databases and applications, there is no complete reference and motif query available at the moment. Cysteine motif database (CMD) is the first online resource that stores all cysteine residues, their flanking motifs with their secondary structure, and propensity values assignment derived from the laboratory data. We extracted more than 3 million cysteine motifs from PDB and UniProt data, annotated with secondary structure assignment, propensity value assignment, and frequency of occurrence and coefficiency of their bonding status. Removal of redundancies generated 15875 unique flanking motifs that are always bonded and 41577 unique patterns that are always nonbonded. Queries are based on the protein ID, FASTA sequence, sequence motif, and secondary structure individually or in batch format using the provided APIs that allow remote users to query our database via third party software and/or high throughput screening/querying. The CMD offers extensive information about the bonded, free cysteine residues, and their motifs that allows in-depth characterization of the sequence motif composition.

  15. CMD: A Database to Store the Bonding States of Cysteine Motifs with Secondary Structures

    Directory of Open Access Journals (Sweden)

    Hamed Bostan

    2012-01-01

    Full Text Available Computational approaches to the disulphide bonding state and its connectivity pattern prediction are based on various descriptors. One descriptor is the amino acid sequence motifs flanking the cysteine residue motifs. Despite the existence of disulphide bonding information in many databases and applications, there is no complete reference and motif query available at the moment. Cysteine motif database (CMD is the first online resource that stores all cysteine residues, their flanking motifs with their secondary structure, and propensity values assignment derived from the laboratory data. We extracted more than 3 million cysteine motifs from PDB and UniProt data, annotated with secondary structure assignment, propensity value assignment, and frequency of occurrence and coefficiency of their bonding status. Removal of redundancies generated 15875 unique flanking motifs that are always bonded and 41577 unique patterns that are always nonbonded. Queries are based on the protein ID, FASTA sequence, sequence motif, and secondary structure individually or in batch format using the provided APIs that allow remote users to query our database via third party software and/or high throughput screening/querying. The CMD offers extensive information about the bonded, free cysteine residues, and their motifs that allows in-depth characterization of the sequence motif composition.

  16. Modeling the interplay of single-stranded binding proteins and nucleic acid secondary structure.

    Science.gov (United States)

    Forties, Robert A; Bundschuh, Ralf

    2010-01-01

    There are many important proteins which bind single-stranded nucleic acids, such as the nucleocapsid protein in HIV and the RecA DNA repair protein in bacteria. The presence of such proteins can strongly alter the secondary structure of the nucleic acid molecules. Therefore, accurate modeling of the interaction between single-stranded nucleic acids and such proteins is essential to fully understand many biological processes. We develop a model for predicting nucleic acid secondary structure in the presence of single-stranded binding proteins, and implement it as an extension of the Vienna RNA Package. All parameters needed to model nucleic acid secondary structures in the absence of proteins have been previously determined. This leaves the footprint and sequence-dependent binding affinity of the protein as adjustable parameters of our model. Using this model we are able to predict the probability of the protein binding at any position in the nucleic acid sequence, the impact of the protein on nucleic acid base pairing, the end-to-end distance distribution for the nucleic acid and FRET distributions for fluorophores attached to the nucleic acid. Source code for our modified version of the Vienna RNA package is freely available at http://bioserv.mps.ohio-state.edu/Vienna+P, implemented in C and running on Linux.

  17. CPU-GPU hybrid accelerating the Zuker algorithm for RNA secondary structure prediction applications.

    Science.gov (United States)

    Lei, Guoqing; Dou, Yong; Wan, Wen; Xia, Fei; Li, Rongchun; Ma, Meng; Zou, Dan

    2012-01-01

    Prediction of ribonucleic acid (RNA) secondary structure remains one of the most important research areas in bioinformatics. The Zuker algorithm is one of the most popular methods of free energy minimization for RNA secondary structure prediction. Thus far, few studies have been reported on the acceleration of the Zuker algorithm on general-purpose processors or on extra accelerators such as Field Programmable Gate-Array (FPGA) and Graphics Processing Units (GPU). To the best of our knowledge, no implementation combines both CPU and extra accelerators, such as GPUs, to accelerate the Zuker algorithm applications. In this paper, a CPU-GPU hybrid computing system that accelerates Zuker algorithm applications for RNA secondary structure prediction is proposed. The computing tasks are allocated between CPU and GPU for parallel cooperate execution. Performance differences between the CPU and the GPU in the task-allocation scheme are considered to obtain workload balance. To improve the hybrid system performance, the Zuker algorithm is optimally implemented with special methods for CPU and GPU architecture. Speedup of 15.93× over optimized multi-core SIMD CPU implementation and performance advantage of 16% over optimized GPU implementation are shown in the experimental results. More than 14% of the sequences are executed on CPU in the hybrid system. The system combining CPU and GPU to accelerate the Zuker algorithm is proven to be promising and can be applied to other bioinformatics applications.

  18. Protein secondary structure prediction for a single-sequence using hidden semi-Markov models

    Directory of Open Access Journals (Sweden)

    Borodovsky Mark

    2006-03-01

    Full Text Available Abstract Background The accuracy of protein secondary structure prediction has been improving steadily towards the 88% estimated theoretical limit. There are two types of prediction algorithms: Single-sequence prediction algorithms imply that information about other (homologous proteins is not available, while algorithms of the second type imply that information about homologous proteins is available, and use it intensively. The single-sequence algorithms could make an important contribution to studies of proteins with no detected homologs, however the accuracy of protein secondary structure prediction from a single-sequence is not as high as when the additional evolutionary information is present. Results In this paper, we further refine and extend the hidden semi-Markov model (HSMM initially considered in the BSPSS algorithm. We introduce an improved residue dependency model by considering the patterns of statistically significant amino acid correlation at structural segment borders. We also derive models that specialize on different sections of the dependency structure and incorporate them into HSMM. In addition, we implement an iterative training method to refine estimates of HSMM parameters. The three-state-per-residue accuracy and other accuracy measures of the new method, IPSSP, are shown to be comparable or better than ones for BSPSS as well as for PSIPRED, tested under the single-sequence condition. Conclusions We have shown that new dependency models and training methods bring further improvements to single-sequence protein secondary structure prediction. The results are obtained under cross-validation conditions using a dataset with no pair of sequences having significant sequence similarity. As new sequences are added to the database it is possible to augment the dependency structure and obtain even higher accuracy. Current and future advances should contribute to the improvement of function prediction for orphan proteins inscrutable

  19. Secondary structure of protamine in sperm nuclei: an infrared spectroscopy study

    Directory of Open Access Journals (Sweden)

    Suau Pedro

    2011-03-01

    Full Text Available Abstract Background Protamines are small basic proteins that condense the DNA in mature spermatozoa. Typical protamines are of simple composition and very arginine-rich, usually in the range of 60-80%. Arginine residues are distributed in a number of stretches separated by neutral amino acids. We have used Fourier transform infrared spectroscopy (FTIR to gain access for the first time to the secondary structure of protamines in sperm nuclei. This technique is particularly well suited to the study of DNA-bound protamine in whole nuclei since it is not affected by turbidity. Results We show that DNA -bound salmon (salmine and squid protamines contain α-helix, β-turns and a proportion of other structures not stabilized by intramolecular hydrogen bonding. No β-sheet was observed. In salmine, the α-helix amounted to ~20%, while in squid protamine it reached ~40%. In contrast, the structure not stabilized by intermolecular hydrogen bonding was more abundant in salmine (~40% than in squid protamine (~20%. Both protamines contained ~40% β-turns. The different helical potential of salmine and squid protamine was confirmed by structure predictions and CD in the presence of trifluoroethanol. Conclusion DNA-bound protamine in sperm nuclei contains large amounts of defined secondary structure stabilized by intramolecular hydrogen bonding. Both salmine and squid protamine contain similar amounts of β-turns, but differ in the proportions of α-helix and non-hydrogen bonded conformations. In spite of the large differences in the proportions of secondary structure motifs between salmon and squid protamines, they appear to be equally efficient in promoting tight hexagonal packing of the DNA molecules in sperm nuclei.

  20. Phylogenetic Network Analysis Revealed the Occurrence of Horizontal Gene Transfer of 16S rRNA in the GenusEnterobacter.

    Science.gov (United States)

    Sato, Mitsuharu; Miyazaki, Kentaro

    2017-01-01

    Horizontal gene transfer (HGT) is a ubiquitous genetic event in bacterial evolution, but it seldom occurs for genes involved in highly complex supramolecules (or biosystems), which consist of many gene products. The ribosome is one such supramolecule, but several bacteria harbor dissimilar and/or chimeric 16S rRNAs in their genomes, suggesting the occurrence of HGT of this gene. However, we know little about whether the genes actually experience HGT and, if so, the frequency of such a transfer. This is primarily because the methods currently employed for phylogenetic analysis (e.g., neighbor-joining, maximum likelihood, and maximum parsimony) of 16S rRNA genes assume point mutation-driven tree-shape evolution as an evolutionary model, which is intrinsically inappropriate to decipher the evolutionary history for genes driven by recombination. To address this issue, we applied a phylogenetic network analysis, which has been used previously for detection of genetic recombination in homologous alleles, to the 16S rRNA gene. We focused on the genus Enterobacter , whose phylogenetic relationships inferred by multi-locus sequence alignment analysis and 16S rRNA sequences are incompatible. All 10 complete genomic sequences were retrieved from the NCBI database, in which 71 16S rRNA genes were included. Neighbor-joining analysis demonstrated that the genes residing in the same genomes clustered, indicating the occurrence of intragenomic recombination. However, as suggested by the low bootstrap values, evolutionary relationships between the clusters were uncertain. We then applied phylogenetic network analysis to representative sequences from each cluster. We found three ancestral 16S rRNA groups; the others were likely created through recursive recombination between the ancestors and chimeric descendants. Despite the large sequence changes caused by the recombination events, the RNA secondary structures were conserved. Successive intergenomic and intragenomic recombination

  1. Rare Events of Intragenus and Intraspecies Horizontal Transfer of the 16S rRNA Gene.

    Science.gov (United States)

    Tian, Ren-Mao; Cai, Lin; Zhang, Wei-Peng; Cao, Hui-Luo; Qian, Pei-Yuan

    2015-07-27

    Horizontal gene transfer (HGT) of operational genes has been widely reported in prokaryotic organisms. However, informational genes such as those involved in transcription and translation processes are very difficult to be horizontally transferred, as described by Woese's complexity hypothesis. Here, we analyzed all of the completed prokaryotic genome sequences (2,143 genomes) in the NCBI (National Center for Biotechnology Information) database, scanned for genomes with high intragenomic heterogeneity of 16S rRNA gene copies, and explored potential HGT events of ribosomal RNA genes based on the phylogeny, genomic organization, and secondary structures of the ribosomal RNA genes. Our results revealed 28 genomes with relatively high intragenomic heterogeneity of multiple 16S rRNA gene copies (lowest pairwise identity gene only occurred at intragenus or intraspecies levels, which is quite different from the HGT of operational genes. Our results improve our understanding regarding the exchange of informational genes. © The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  2. Simultaneous Analysis of Secondary Structure and Light Scattering from Circular Dichroism Titrations: Application to Vectofusin-1

    Science.gov (United States)

    Vermeer, Louic S.; Marquette, Arnaud; Schoup, Michel; Fenard, David; Galy, Anne; Bechinger, Burkhard

    2016-01-01

    Circular Dichroism data are often decomposed into their constituent spectra to quantify the secondary structure of peptides or proteins but the estimation of the secondary structure content fails when light scattering leads to spectral distortion. If peptide-induced liposome self-association occurs, subtracting control curves cannot correct for this. We show that if the cause of the light scattering is independent from the peptide structural changes, the CD spectra can be corrected using principal component analysis (PCA). The light scattering itself is analysed and found to be in good agreement with backscattering experiments. This method therefore allows to simultaneously follow structural changes related to peptide-liposome binding as well as peptide induced liposome self-association. We apply this method to study the structural changes and liposome binding of vectofusin-1, a transduction enhancing peptide used in lentivirus based gene therapy. Vectofusin-1 binds to POPC/POPS liposomes, causing a reversal of the negative liposome charge at high peptide concentrations. When the peptide charges exactly neutralise the lipid charges on both leaflets reversible liposome self-association occurs. These results are in good agreement with biological observations and provide further insight into the conditions required for efficent transduction enhancement. PMID:28004740

  3. DNA secondary structure is influenced by genetic variation and alters susceptibility to de novo translocation

    Directory of Open Access Journals (Sweden)

    Tsutsumi Makiko

    2011-09-01

    Full Text Available Abstract Background Cumulative evidence suggests that DNA secondary structures impact DNA replication, transcription and genomic rearrangements. One of the best studied examples is the recurrent constitutional t(11;22 in humans that is mediated by potentially cruciform-forming sequences at the breakpoints, palindromic AT-rich repeats (PATRRs. We previously demonstrated that polymorphisms of PATRR sequences affect the frequency of de novo t(11;22s in sperm samples from normal healthy males. These studies were designed to determine whether PATRR polymorphisms affect DNA secondary structure, thus leading to variation in translocation frequency. Methods We studied the potential for DNA cruciform formation for several PATRR11 polymorphic alleles using mobility shift analysis in gel electrophoresis as well as by direct visualization of the DNA by atomic force microscopy. The structural data for various alleles were compared with the frequency of de novo t(11;22s the allele produced. Results The data indicate that the propensity for DNA cruciform structure of each polymorphic allele correlates with the frequency of de novo t(11;22s produced (r = 0.77, P = 0.01. Conclusions Although indirect, our results strongly suggest that the PATRR adopts unstable cruciform structures during spermatogenesis that act as translocation hotspots in humans.

  4. CompaRNA: a server for continuous benchmarking of automated methods for RNA secondary structure prediction

    Science.gov (United States)

    Puton, Tomasz; Kozlowski, Lukasz P.; Rother, Kristian M.; Bujnicki, Janusz M.

    2013-01-01

    We present a continuous benchmarking approach for the assessment of RNA secondary structure prediction methods implemented in the CompaRNA web server. As of 3 October 2012, the performance of 28 single-sequence and 13 comparative methods has been evaluated on RNA sequences/structures released weekly by the Protein Data Bank. We also provide a static benchmark generated on RNA 2D structures derived from the RNAstrand database. Benchmarks on both data sets offer insight into the relative performance of RNA secondary structure prediction methods on RNAs of different size and with respect to different types of structure. According to our tests, on the average, the most accurate predictions obtained by a comparative approach are generated by CentroidAlifold, MXScarna, RNAalifold and TurboFold. On the average, the most accurate predictions obtained by single-sequence analyses are generated by CentroidFold, ContextFold and IPknot. The best comparative methods typically outperform the best single-sequence methods if an alignment of homologous RNA sequences is available. This article presents the results of our benchmarks as of 3 October 2012, whereas the rankings presented online are continuously updated. We will gladly include new prediction methods and new measures of accuracy in the new editions of CompaRNA benchmarks. PMID:23435231

  5. Protein energetic conformational analysis from NMR chemical shifts (PECAN) and its use in determining secondary structural elements

    Energy Technology Data Exchange (ETDEWEB)

    Eghbalnia, Hamid R.; Wang Liya; Bahrami, Arash [National Magnetic Resonance Facility at Madison, Biochemistry Department (United States); Assadi, Amir [University of Wisconsin-Madison, Mathematics Department (United States); Markley, John L. [National Magnetic Resonance Facility at Madison, Biochemistry Department (United States)], E-mail: eghbalni@nmrfam.wisc.edu

    2005-05-15

    We present an energy model that combines information from the amino acid sequence of a protein and available NMR chemical shifts for the purposes of identifying low energy conformations and determining elements of secondary structure. The model ('PECAN', Protein Energetic Conformational Analysis from NMR chemical shifts) optimizes a combination of sequence information and residue-specific statistical energy function to yield energetic descriptions most favorable to predicting secondary structure. Compared to prior methods for secondary structure determination, PECAN provides increased accuracy and range, particularly in regions of extended structure. Moreover, PECAN uses the energetics to identify residues located at the boundaries between regions of predicted secondary structure that may not fit the stringent secondary structure class definitions. The energy model offers insights into the local energetic patterns that underlie conformational preferences. For example, it shows that the information content for defining secondary structure is localized about a residue and reaches a maximum when two residues on either side are considered. The current release of the PECAN software determines the well-defined regions of secondary structure in novel proteins with assigned chemical shifts with an overall accuracy of 90%, which is close to the practical limit of achievable accuracy in classifying the states.

  6. Effect of preparation conditions on protein secondary structure and biofilm formation of kafirin.

    Science.gov (United States)

    Gao, Chunli; Taylor, Janet; Wellner, Nikolaus; Byaruhanga, Yusuf B; Parker, Mary L; Mills, E N Clare; Belton, Peter S

    2005-01-26

    Various extraction and drying conditions for the isolation of kafirin from dry-milled, whole grain sorghum have been investigated, with a view to optimizing extraction of the protein for commercial food coatings and packaging films. The addition of sodium hydroxide to an aqueous ethanol extractant increased the yield and solubility of kafirin. Subsequent heat drying at 40 degrees C was shown to cause the kafirin to aggregate as indicated by an increase in intermolecular beta-sheets. Extraction of the flour using ethanol (70%, w/w) with 0.5% (w/w) sodium metabisulfite and 0.35% (w/w) sodium hydroxide at 70 degrees C followed by freeze-drying of the protein was found to produce a yield of 54% kafirin with good film-forming properties. The kafirin films were assessed for their sensory properties, tensile strength, strain, and water vapor permeability. Fourier transform infrared spectroscopy was used to study the secondary structure of the extracted kafirins. The best films were made with kafirin containing a large proportion of nativelike alpha-helical structures with little intermolecular beta-sheet content as indicated by the Fourier transform infrared reflectance peak intensity ratios associated with these secondary structures. The principal factor affecting the secondary structure of the protein appeared to be the temperature at which the protein was dried. Heat drying resulted in a greater proportion of intermolecular beta-sheets. Any industrial-scale extraction must therefore minimize protein aggregation and maximize native alpha-helical structures to achieve optimal film quality.

  7. Teaching the foundations of quantum mechanics in secondary school: a proposed conceptual structure

    Directory of Open Access Journals (Sweden)

    Maria de los Angeles Fanaro

    2009-03-01

    Full Text Available This paper is part of a doctoral thesis that investigates Basic Quantum Mechanics (QM teaching in high school. A Conceptual Structure of Reference (CSR based on the Path Integral Method of Feynman (1965 was rebuilt and a Proposed Conceptual Structure for Teaching (PCST (Otero, 2006, 2007 the basics of Quantum Mechanics at secondary school was designed, analysed and carried out. This PCST does not follow the historical route and it is complementary to the canonical formalism. The concepts: probability distribution, quantum system, x(t alternative, amplitude of probability, sum of probability amplitude, action, Planck's constant, and classic-quantum transition were rebuilt with the students. Mathematical formalism was avoided by using simulation software assistance. The Proposed Conceptual Structure for Teaching (PCST is described and some results from the test carried out by the class group are discussed. This information allows the analysis of the Conceptual Structure Effectively Reconstructed (CSER to be initiated with the students.

  8. Secondary structure prediction of protein constructs using random incremental truncation and vacuum-ultraviolet CD spectroscopy

    CERN Document Server

    Pukáncsik, M; Matsuo, K; Gekko, K; Hart, D; Kézsmárki, I; Vértessy, B G

    2014-01-01

    A novel uracil-DNA degrading protein factor (termed UDE) was identified in Drosophila melanogaster with no significant structural and functional homology to other uracil-DNA binding or processing factors. Determination of the 3D structure of UDE will be a true breakthrough in description of the molecular mechanism of action of UDE catalysis, as well as in general uracil-recognition and nuclease action. The revolutionary ESPRIT technology was applied to the novel protein UDE to overcome problems in identifying soluble expressing constructs given the absence of precise information on domain content and arrangement. Nine specimen from the created numerous truncated constructs of UDE were choosen to dechiper structural and functional relationships. VUVCD with neural network was performed to define the secondary structure content and location of UDE and its truncated variants. The quantitative analysis demonstrated exclusive {\\alpha}-helical content for the full-length protein, which is preserved in the truncated ...

  9. Perturbation-induced secondary flow structures due to fractured stents in arterial curvatures

    Science.gov (United States)

    Bulusu, Kartik V.; Popma, Christopher; Penna, Leanne; Plesniak, Michael W.

    2012-11-01

    An in vitro experimental investigation of secondary flow structures was performed downstream of a model stent that embodied a ``Type-IV'' stent fracture, i.e. complete transverse fracture of elements and element displacement (of 3 diameters). One part of the fractured stent was located in the curved region of a test section comprised of a 180-degree bent tube, and the velocity field measured with PIV. Secondary flow morphologies downstream of the stent were identified with a continuous wavelet transform (CWT) algorithm (PIVlet 1.2) using a 2D Ricker wavelet. A comparison of wavelet transformed vorticity fields of fractured and unfractured model stents is presented under physiological inflow conditions. During systolic deceleration, a breakdown in symmetry of vortical structures occurred with the unfractured stent, but not with the fractured model stent. Potential mechanisms to explain the differences in secondary flow morphologies include redirection of vorticity from the meridional plane of the bend to the normal plane and diffusion of vorticity. Supported by the National Science Foundation, Grant No. CBET-0828903 and GW Center for Biomimetics and Bioinspired Engineering (COBRE).

  10. Going deep into protein secondary structure with synchrotron radiation circular dichroism spectroscopy.

    Science.gov (United States)

    Kumagai, Patricia S; Araujo, Ana P U; Lopes, Jose L S

    2017-10-01

    Circular dichroism (CD) spectroscopy is a fast, powerful, well-established, and widely used analytical technique in the biophysical and structural biology community to study protein secondary structure and to track changes in protein conformation in different environments. The use of the intense light of a synchrotron beam as the light source for collecting CD measurements has emerged as an enhanced method, known as synchrotron radiation circular dichroism (SRCD) spectroscopy, that has several advantages over the conventional CD method, including a significant spectral range extension for data collection, deeper access to the lower limit (cut-off) of conventional CD spectroscopy, an improved signal-to-noise ratio to increase accuracy in the measurements, and the possibility to collect measurements in highly absorbing solutions. In this review, we discuss different applications of the SRCD technique by researchers from Latin America. In this context, we specifically look at the use of this method for examining the secondary structure and conformational behavior of proteins belonging to the four main classes of the hierarchical protein domain classification CATH (Class, Architecture, Topology, Homology) database, focusing on the advantages and improvements associated with SRCD spectroscopy in terms of characterizing proteins composed of different structural elements.

  11. Does family structure matter? Comparing the life goals and aspirations of learners in secondary schools

    Directory of Open Access Journals (Sweden)

    Eugene Lee Davids

    2013-01-01

    Full Text Available The aim of this study was to compare the goals and aspirations of learners from single- and two-parent families. The study used a quantitative methodology with a cross-sectional comparative group design. The sample consisted of 853 Grade 11 learners from secondary schools in the Northern, Southern and Metro Central education districts in the Western Cape. The data were collected using the Aspirations Index and a short biographical questionnaire. The results suggest that there was a significant main effect of family structure on certain goals and aspirations of learners in secondary schools. These goals and aspirations included wealth, image, personal growth, relationships, and health. Furthermore, learners in single-parent families placed more emphasis on intrinsic goals.

  12. The effect of structural disorder on the secondary electron emission of graphite

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    L. A. Gonzalez

    2016-09-01

    Full Text Available The dependance of the secondary electron yield (SEY on the degree of crystallinity of graphite has been investigated during the amorphization of a highly oriented pyrolytic graphite (HOPG samples by means of Ar+ bombardment. Photoemission and Raman spectroscopies were used to follow the structural damage while the SEY curves were measured from very low energies up to 1000 eV. We found that the increase of lattice defects lowers the contribution of the π electrons in the valence band and loss spectra and smears out the intense modulations in the low energy secondary electron yield (LE-SEY curve. Raman spectroscopy results showed that ion induced lattice amorphization is confined in a near-surface layer. The evolution of SEY curves was observed with the progressive Ar+ dosage after crystal damage as due to the modification of the electronic transport properties within the damaged near surface layer.

  13. Multithreaded comparative RNA secondary structure prediction using stochastic context-free grammars

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    Værum Morten

    2011-04-01

    Full Text Available Abstract Background The prediction of the structure of large RNAs remains a particular challenge in bioinformatics, due to the computational complexity and low levels of accuracy of state-of-the-art algorithms. The pfold model couples a stochastic context-free grammar to phylogenetic analysis for a high accuracy in predictions, but the time complexity of the algorithm and underflow errors have prevented its use for long alignments. Here we present PPfold, a multithreaded version of pfold, which is capable of predicting the structure of large RNA alignments accurately on practical timescales. Results We have distributed both the phylogenetic calculations and the inside-outside algorithm in PPfold, resulting in a significant reduction of runtime on multicore machines. We have addressed the floating-point underflow problems of pfold by implementing an extended-exponent datatype, enabling PPfold to be used for large-scale RNA structure predictions. We have also improved the user interface and portability: alongside standalone executable and Java source code of the program, PPfold is also available as a free plugin to the CLC Workbenches. We have evaluated the accuracy of PPfold using BRaliBase I tests, and demonstrated its practical use by predicting the secondary structure of an alignment of 24 complete HIV-1 genomes in 65 minutes on an 8-core machine and identifying several known structural elements in the prediction. Conclusions PPfold is the first parallelized comparative RNA structure prediction algorithm to date. Based on the pfold model, PPfold is capable of fast, high-quality predictions of large RNA secondary structures, such as the genomes of RNA viruses or long genomic transcripts. The techniques used in the parallelization of this algorithm may be of general applicability to other bioinformatics algorithms.

  14. Species-specific identification of Dekkera/Brettanomyces yeasts by fluorescently labeled DNA probes targeting the 26S rRNA.

    Science.gov (United States)

    Röder, Christoph; König, Helmut; Fröhlich, Jürgen

    2007-09-01

    Sequencing of the complete 26S rRNA genes of all Dekkera/Brettanomyces species colonizing different beverages revealed the potential for a specific primer and probe design to support diagnostic PCR approaches and FISH. By analysis of the complete 26S rRNA genes of all five currently known Dekkera/Brettanomyces species (Dekkera bruxellensis, D. anomala, Brettanomyces custersianus, B. nanus and B. naardenensis), several regions with high nucleotide sequence variability yet distinct from the D1/D2 domains were identified. FISH species-specific probes targeting the 26S rRNA gene's most variable regions were designed. Accessibility of probe targets for hybridization was facilitated by the construction of partially complementary 'side'-labeled probes, based on secondary structure models of the rRNA sequences. The specificity and routine applicability of the FISH-based method for yeast identification were tested by analyzing different wine isolates. Investigation of the prevalence of Dekkera/Brettanomyces yeasts in the German viticultural regions Wonnegau, Nierstein and Bingen (Rhinehesse, Rhineland-Palatinate) resulted in the isolation of 37 D. bruxellensis strains from 291 wine samples.

  15. Protein secondary structure appears to be robust under in silico evolution while protein disorder appears not to be.

    KAUST Repository

    Schaefer, Christian

    2010-01-16

    MOTIVATION: The mutation of amino acids often impacts protein function and structure. Mutations without negative effect sustain evolutionary pressure. We study a particular aspect of structural robustness with respect to mutations: regular protein secondary structure and natively unstructured (intrinsically disordered) regions. Is the formation of regular secondary structure an intrinsic feature of amino acid sequences, or is it a feature that is lost upon mutation and is maintained by evolution against the odds? Similarly, is disorder an intrinsic sequence feature or is it difficult to maintain? To tackle these questions, we in silico mutated native protein sequences into random sequence-like ensembles and monitored the change in predicted secondary structure and disorder. RESULTS: We established that by our coarse-grained measures for change, predictions and observations were similar, suggesting that our results were not biased by prediction mistakes. Changes in secondary structure and disorder predictions were linearly proportional to the change in sequence. Surprisingly, neither the content nor the length distribution for the predicted secondary structure changed substantially. Regions with long disorder behaved differently in that significantly fewer such regions were predicted after a few mutation steps. Our findings suggest that the formation of regular secondary structure is an intrinsic feature of random amino acid sequences, while the formation of long-disordered regions is not an intrinsic feature of proteins with disordered regions. Put differently, helices and strands appear to be maintained easily by evolution, whereas maintaining disordered regions appears difficult. Neutral mutations with respect to disorder are therefore very unlikely.

  16. The Interplay between Adolescent Needs and Secondary School Structures: Fostering Developmentally Responsive Middle and High School Environments across the Transition

    Science.gov (United States)

    Ellerbrock, Cheryl R.; Kiefer, Sarah M.

    2013-01-01

    Understanding the developmental responsiveness of secondary school environments may be an important factor in supporting students as they make the transition from one school to the next. Students' needs may or may not be met depending on the nature of the fit between their basic and developmental needs and secondary school structures at the middle…

  17. A quantitative analysis of secondary RNA structure using domination based parameters on trees

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    Zou Yue

    2006-03-01

    Full Text Available Abstract Background It has become increasingly apparent that a comprehensive database of RNA motifs is essential in order to achieve new goals in genomic and proteomic research. Secondary RNA structures have frequently been represented by various modeling methods as graph-theoretic trees. Using graph theory as a modeling tool allows the vast resources of graphical invariants to be utilized to numerically identify secondary RNA motifs. The domination number of a graph is a graphical invariant that is sensitive to even a slight change in the structure of a tree. The invariants selected in this study are variations of the domination number of a graph. These graphical invariants are partitioned into two classes, and we define two parameters based on each of these classes. These parameters are calculated for all small order trees and a statistical analysis of the resulting data is conducted to determine if the values of these parameters can be utilized to identify which trees of orders seven and eight are RNA-like in structure. Results The statistical analysis shows that the domination based parameters correctly distinguish between the trees that represent native structures and those that are not likely candidates to represent RNA. Some of the trees previously identified as candidate structures are found to be "very" RNA like, while others are not, thereby refining the space of structures likely to be found as representing secondary RNA structure. Conclusion Search algorithms are available that mine nucleotide sequence databases. However, the number of motifs identified can be quite large, making a further search for similar motif computationally difficult. Much of the work in the bioinformatics arena is toward the development of better algorithms to address the computational problem. This work, on the other hand, uses mathematical descriptors to more clearly characterize the RNA motifs and thereby reduce the corresponding search space. These

  18. Analysis of secondary structural elements in human microRNA hairpin precursors.

    Science.gov (United States)

    Liu, Biao; Childs-Disney, Jessica L; Znosko, Brent M; Wang, Dan; Fallahi, Mohammad; Gallo, Steven M; Disney, Matthew D

    2016-03-01

    MicroRNAs (miRNAs) regulate gene expression by targeting complementary mRNAs for destruction or translational repression. Aberrant expression of miRNAs has been associated with various diseases including cancer, thus making them interesting therapeutic targets. The composite of secondary structural elements that comprise miRNAs could aid the design of small molecules that modulate their function. We analyzed the secondary structural elements, or motifs, present in all human miRNA hairpin precursors and compared them to highly expressed human RNAs with known structures and other RNAs from various organisms. Amongst human miRNAs, there are 3808 are unique motifs, many residing in processing sites. Further, we identified motifs in miRNAs that are not present in other highly expressed human RNAs, desirable targets for small molecules. MiRNA motifs were incorporated into a searchable database that is freely available. We also analyzed the most frequently occurring bulges and internal loops for each RNA class and found that the smallest loops possible prevail. However, the distribution of loops and the preferred closing base pairs were unique to each class. Collectively, we have completed a broad survey of motifs found in human miRNA precursors, highly expressed human RNAs, and RNAs from other organisms. Interestingly, unique motifs were identified in human miRNA processing sites, binding to which could inhibit miRNA maturation and hence function.

  19. How does vegetation structure influence woodpeckers and secondary cavity nesting birds in African cork oak forest?

    Science.gov (United States)

    Segura, Amalia

    2017-08-01

    The Great Spotted Woodpecker provides important information about the status of a forest in terms of structure and age. As a primary cavity creator, it provides small-medium size cavities for passerines. However, despite its interest as an ecosystem engineer, studies of this species in Africa are scarce. Here, spatially explicit predictive models were used to investigate how forest structural variables are related to both the Great Spotted Woodpecker and secondary cavity nesting birds in Maamora cork oak forest (northwest Morocco). A positive association between Great Spotted Woodpecker and both dead-tree density and large mature trees (>60 cm dbh) was found. This study area, Maamora, has an old-growth forest structure incorporating a broad range of size and condition of live and dead trees, favouring Great Spotted Woodpecker by providing high availability of foraging and excavating sites. Secondary cavity nesting birds, represented by Great Tit, African Blue Tit, and Hoopoe, were predicted by Great Spotted Woodpecker detections. The findings suggest that the conservation of the Maamora cork oak forest could be key to maintaining these hole-nesting birds. However, this forest is threatened by forestry practises and livestock overgrazing and the challenge is therefore to find sustainable management strategies that ensure conservation while allowing its exploitation.

  20. AFM observation of silk fibroin on mica substrates: morphologies reflecting the secondary structures

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Kazushi; Tsuboi, Yasuyuki; Itaya, Akira

    2003-09-01

    Bombyx mori silk fibroin was fixed on mica substrates by cast of aqueous fibroin solutions, and the microscopic morphologies of the samples were revealed by means of atomic force microscopy. By adjusting the method used to prepare the solution, we succeeded in forming quasi-2-dimensional thin films in which a network of fibroin molecules developed over the substrate. The film network consisted of fibroin in a random coil structure. The morphology of the network changed after thermal or methanol treatments, which are known to convert the secondary structure of fibroin from the random coil to the {beta}-sheet type. In both of these cases, the network morphology disappeared and characteristic island-like morphologies appeared. On the other hand, temporally evolving gelation occurred in a fibroin solution due to the formation of {beta}-sheet crystals. Such islands were also observable in a specimen prepared by the cast of the gel-containing solution. Based on these results, it was concluded that the islands consist of {beta}-sheet crystals. Of particular interest is the observation that all of the islands had a common thickness value of 1.3 nm. These morphologies are discussed in terms of the secondary structure of fibroin.

  1. Effects of high hydrostatic pressure on secondary structure and emulsifying behavior of sweet potato protein

    Science.gov (United States)

    Mehmood Khan, Nasir; Mu, Tai-Hua; Sun, Hong-Nan; Zhang, Miao; Chen, Jing-Wang

    2015-04-01

    In this study, secondary structures of sweet potato protein (SPP) after high hydrostatic pressure (HHP) treatment (200-600 MPa) were evaluated and emulsifying properties of emulsions with HHP-treated SPP solutions in different pH values (3, 6, and 9) were investigated. Circular dichroism analysis confirmed the modification of the SPP secondary structure. Surface hydrophobicity increased at pH 3 and decreased at 6 and 9. Emulsifying activity index at pH 6 increased with an increase in pressure, whereas emulsifying stability index increased at pH 6 and 9. Oil droplet sizes decreased, while volume frequency distribution of the smaller droplets increased at pH 3 and 6 with the HHP treatment. Emulsion viscosity increased at pH 6 and 9 and pseudo-plastic flow behaviors were not altered for all emulsions produced with HHP-treated SPP. These results suggested that HHP could modify the SPP structure for better emulsifying properties, which could increase the use of SPP emulsion in the food industry.

  2. Secondary Structure Preferences of Mn2+ Binding Sites in Bacterial Proteins

    Directory of Open Access Journals (Sweden)

    Tatyana Aleksandrovna Khrustaleva

    2014-01-01

    Full Text Available 3D structures of proteins with coordinated Mn2+ ions from bacteria with low, average, and high genomic GC-content have been analyzed (149 PDB files were used. Major Mn2+ binders are aspartic acid (6.82% of Asp residues, histidine (14.76% of His residues, and glutamic acid (3.51% of Glu residues. We found out that the motif of secondary structure “beta strand-major binder-random coil” is overrepresented around all the three major Mn2+ binders. That motif may be followed by either alpha helix or beta strand. Beta strands near Mn2+ binding residues should be stable because they are enriched by such beta formers as valine and isoleucine, as well as by specific combinations of hydrophobic and hydrophilic amino acid residues characteristic to beta sheet. In the group of proteins from GC-rich bacteria glutamic acid residues situated in alpha helices frequently coordinate Mn2+ ions, probably, because of the decrease of Lys usage under the influence of mutational GC-pressure. On the other hand, the percentage of Mn2+ sites with at least one amino acid in the “beta strand-major binder-random coil” motif of secondary structure (77.88% does not depend on genomic GC-content.

  3. Change in Glutenin Macropolymer Secondary Structure in Wheat Sourdough Fermentation by FTIR.

    Science.gov (United States)

    Wang, Jinshui; Yue, Yuanyuan; Liu, Tiantian; Zhang, Bin; Wang, Zhenlei; Zhang, Changfu

    2017-06-01

    Wheat sourdough was prepared by fermentation with Lactobacillus plantarum M616 and yeast in the present study. The change in secondary structure of glutenin macropolymer (GMP) in wheat sourdough fermentation for 4 and 12 h was determined using Fourier transform infrared spectroscopy, and then the resultant spectra were Fourier self-deconvoluted of the amide I band in the region from 1600 to 1700 cm -1 . Significant different spectra especially in the amide I band for GMP from sourdough fermented with L. plantarum M616 (SL) and with L. plantarum M616 and yeast (SLY) were found in respect of control dough (CK), dough with acids (SA), and sourdough fermented with yeast (SY) at 4 and 12 h of fermentation. The loss of α-helix structure in SL, SLY, and SA samples was noticed during fermentation. Compared with CK and SY, SL, SLY, and SA samples showed significant decrease (p fermentation. In addition, β-turns in SL sourdough decrease, and the relative areas of random coil increase significantly (p fermentation. The modified secondary structure of GMP makes more sensitive to proteolysis by means of cereal enzymes.

  4. Prediction algorithm for amino acid types with their secondary structure in proteins (PLATON) using chemical shifts.

    Science.gov (United States)

    Labudde, D; Leitner, D; Krüger, M; Oschkinat, H

    2003-01-01

    The algorithm PLATON is able to assign sets of chemical shifts derived from a single residue to amino acid types with its secondary structure (amino acid species). A subsequent ranking procedure using optionally two different penalty functions yields predictions for possible amino acid species for the given set of chemical shifts. This was demonstrated in the case of the alpha-spectrin SH3 domain and applied to 9 further protein data sets taken from the BioMagRes database. A database consisting of reference chemical shift patterns (reference CSPs) was generated from assigned chemical shifts of proteins with known 3D-structure. This reference CSP database is used in our approach for extracting distributions of amino acid types with their most likely secondary structure elements (namely alpha-helix, beta-sheet, and coil) for single amino acids by comparison with query CSPs. Results obtained for the 10 investigated proteins indicates that the percentage of correct amino acid species in the first three positions in the ranking list, ranges from 71.4% to 93.2% for the more favorable penalty function. Where only the top result of the ranking list for these 10 proteins is considered, 36.5% to 83.1% of the amino acid species are correctly predicted. The main advantage of our approach, over other methods that rely on average chemical shift values is the ability to increase database content by incorporating newly derived CSPs, and therefore to improve PLATON's performance over time.

  5. In Silico Analysis of β-Galactosidases Primary and Secondary Structure in relation to Temperature Adaptation

    Directory of Open Access Journals (Sweden)

    Vijay Kumar

    2014-01-01

    Full Text Available β-D-Galactosidases (EC 3.2.1.23 hydrolyze the terminal nonreducing β-D-galactose residues in β-D-galactosides and are ubiquitously present in all life forms including extremophiles. Eighteen microbial β-galactosidase protein sequences, six each from psychrophilic, mesophilic, and thermophilic microbes, were analyzed. Primary structure reveals alanine, glycine, serine, and arginine to be higher in psychrophilic β-galactosidases whereas valine, glutamine, glutamic acid, phenylalanine, threonine, and tyrosine are found to be statistically preferred by thermophilic β-galactosidases. Cold active β-galactosidase has a strong preference towards tiny and small amino acids, whereas high temperature inhabitants had higher content of basic and aromatic amino acids. Thermophilic β-galactosidases have higher percentage of α-helix region responsible for temperature tolerance while cold loving β-galactosidases had higher percentage of sheet and coil region. Secondary structure analysis revealed that charged and aromatic amino acids were significant for sheet region of thermophiles. Alanine was found to be significant and high in the helix region of psychrophiles and valine counters in thermophilic β-galactosidase. Coil region of cold active β-galactosidase has higher content of tiny amino acids which explains their high catalytic efficiency over their counterparts from thermal habitat. The present study has revealed the preference or prevalence of certain amino acids in primary and secondary structure of psychrophilic, mesophilic, and thermophilic β-galactosidase.

  6. A consensus secondary structure of ITS2 in the chlorophyta identified by phylogenetic reconstruction.

    Science.gov (United States)

    Caisová, Lenka; Marin, Birger; Melkonian, Michael

    2013-07-01

    The definition of species plays a pivotal role in biology. It has been proposed that Compensatory Base Changes (CBCs) in the fast-evolving Internal Transcribed Spacer 2 (ITS2) correlate with speciation and thus can be used to distinguish species. The applicability of CBC - based species concepts using ITS2, however, rests on the homology of the investigated ITS2 positions. We studied the ITS2 molecule of 147 strains of Chlorophyceae (Chlorophyta, Viridiplantae) including 26 new sequences in the order Chaetophorales, and compared their secondary structures to ITS2 in the sister class Ulvophyceae, represented by the order Ulvales. Using a phylogenetic/comparative approach, it was possible to identify 1) the first consensus structure model of the ITS2 molecule that can be applied to two classes of green algae [Ulvophyceae (Ulvales), Chlorophyceae] and 2) landmarks (the spacer regions separating the ITS2 Helices) for more robust prediction of the secondary structures in green algae. Moreover, we found that CBCs in homologous positions in these 147 strains (representing 115 validly described species) are either completely absent or mostly associated with internal branches representing higher order taxonomic levels (genera, families, orders). As reported for the Ulvales, CBCs are not diagnostic at the species level in the dataset used. Copyright © 2013 Elsevier GmbH. All rights reserved.

  7. In silico methods for co-transcriptional RNA secondary structure prediction and for investigating alternative RNA structure expression.

    Science.gov (United States)

    Meyer, Irmtraud M

    2017-05-01

    RNA transcripts are the primary products of active genes in any living organism, including many viruses. Their cellular destiny not only depends on primary sequence signals, but can also be determined by RNA structure. Recent experimental evidence shows that many transcripts can be assigned more than a single functional RNA structure throughout their cellular life and that structure formation happens co-transcriptionally, i.e. as the transcript is synthesised in the cell. Moreover, functional RNA structures are not limited to non-coding transcripts, but can also feature in coding transcripts. The picture that now emerges is that RNA structures constitute an additional layer of information that can be encoded in any RNA transcript (and on top of other layers of information such as protein-context) in order to exert a wide range of functional roles. Moreover, different encoded RNA structures can be expressed at different stages of a transcript's life in order to alter the transcript's behaviour depending on its actual cellular context. Similar to the concept of alternative splicing for protein-coding genes, where a single transcript can yield different proteins depending on cellular context, it is thus appropriate to propose the notion of alternative RNA structure expression for any given transcript. This review introduces several computational strategies that my group developed to detect different aspects of RNA structure expression in vivo. Two aspects are of particular interest to us: (1) RNA secondary structure features that emerge during co-transcriptional folding and (2) functional RNA structure features that are expressed at different times of a transcript's life and potentially mutually exclusive. Copyright © 2017. Published by Elsevier Inc.

  8. Structure of the secondary xylem of Aniba Aubl. species from the Brazilian Amazon

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    Cláudia Viana Urbinati

    2014-09-01

    Full Text Available The aim of this study was to characterize the wood of Aniba species from the Brazilian Amazon, on the basis of specimens in the wood collection of the Herbarium of the Museu Paraense Emílio Goeldi, in the city of Belém, Brazil. The species were found to present a homogeneous structure in the secondary xylem, as defined by the location of oil cells; the presence of tyloses and crystals; and singularities of the radial and axial parenchyma.

  9. Secondary Structure Prediction of Protein using Resilient Back Propagation Learning Algorithm

    Directory of Open Access Journals (Sweden)

    Jyotshna Dongardive

    2015-12-01

    Full Text Available The paper proposes a neural network based approach to predict secondary structure of protein. It uses Multilayer Feed Forward Network (MLFN with resilient back propagation as the learning algorithm. Point Accepted Mutation (PAM is adopted as the encoding scheme and CB396 data set is used for the training and testing of the network. Overall accuracy of the network has been experimentally calculated with different window sizes for the sliding window scheme and by varying the number of units in the hidden layer. The best results were obtained with eleven as the window size and seven as the number of units in the hidden layer.

  10. Two-dimensional dynamics of a free molecular chain with a secondary structure

    DEFF Research Database (Denmark)

    Zolotaryuk, Alexander; Christiansen, Peter Leth; Savin, A.V.

    1996-01-01

    A simple two-dimensional (2D) model of an isolated (free) molecular chain with primary and secondary structures has been suggested and investigated both analytically and numerically. This model can be considered as the simplest generalization of the well-known Fermi-Pasta-Ulam model of an anharmo......) supersonic pulses of longitudinal compression propagating together with localized transverse thickening (bulge) have been found. Some peculiar stability properties of these two-component soliton solutions have been discovered by using numerical techniques developed in this paper....

  11. Effect of secondary structure on the thermodynamics and kinetics of PNA hybridization to DNA hairpins

    DEFF Research Database (Denmark)

    Kushon, S A; Jordan, J P; Seifert, J L

    2001-01-01

    structures in both target and probe molecules are shown to depress the melting temperatures and free energies of the probe-target duplexes. Kinetic analysis of hybridization yields reaction rates that are up to 160-fold slower than hybridization between two unstructured strands. The thermodynamic and kinetic......-DNA and DNA-DNA duplexes can be formed with these target hairpins, even when the melting temperatures for the resulting duplexes are up to 50 degrees C lower than that of the hairpin target. Both hairpin/single-stranded and hairpin/hairpin interactions are considered in the scope of these studies. Secondary...

  12. An evolutionary method for learning HMM structure: prediction of protein secondary structure

    DEFF Research Database (Denmark)

    Won, Kyoung-Jae; Hamelryck, Thomas; Prügel-Bennett, Adam

    2007-01-01

    of such Block-HMMs. After each step of the GA, the standard HMM estimation algorithm (the Baum-Welch algorithm) was used to update model parameters. The final HMM captures several features of protein sequence and structure, with its own HMM grammar. In contrast to neural network based predictors, the evolved...... HMM also calculates the probabilities associated with the predictions. We carefully examined the performance of the HMM based predictor, both under the multiple- and single-sequence...

  13. Structures in secondary flow under simple harmonic inflow in a 180 degree curved pipe model of an artery

    Science.gov (United States)

    Glenn, Autumn L.; Seagrave, Sarah L.; Bulusu, Kartik V.; Plesniak, Michael W.

    2011-11-01

    Inward centrifuging of fluid in a 180 degree curved pipe leads to development of secondary flow vortical structures. These Dean's vortices have been widely studied in steady flows. Complex secondary flow structures were observed under (unsteady) physiological flow forcing associated with the cardiac cycle, as well as simple harmonic forcing. These structures were investigated under several simple harmonic inflow conditions with phase-locked 2-D PIV measurements to examine the formation of coherent structures in the secondary flow. Experimental velocity field data were acquired at various cross-sectional planes along the bend. Multiple vortex pairs were observed at 90 degrees into the bend for all waveforms investigated. The overarching goal of this study is to understand the effect of driving waveform characteristics, i.e. period, flow acceleration, etc. on secondary flow morphologies and to characterize these morphologies in terms of dimensionless parameters describing the flow. Supported by the National Science Foundation under Grant No. CBET-0828903.

  14. Enhancement of accuracy and efficiency for RNA secondary structure prediction by sequence segmentation and MapReduce.

    Science.gov (United States)

    Zhang, Boyu; Yehdego, Daniel T; Johnson, Kyle L; Leung, Ming-Ying; Taufer, Michela

    2013-01-01

    Ribonucleic acid (RNA) molecules play important roles in many biological processes including gene expression and regulation. Their secondary structures are crucial for the RNA functionality, and the prediction of the secondary structures is widely studied. Our previous research shows that cutting long sequences into shorter chunks, predicting secondary structures of the chunks independently using thermodynamic methods, and reconstructing the entire secondary structure from the predicted chunk structures can yield better accuracy than predicting the secondary structure using the RNA sequence as a whole. The chunking, prediction, and reconstruction processes can use different methods and parameters, some of which produce more accurate predictions than others. In this paper, we study the prediction accuracy and efficiency of three different chunking methods using seven popular secondary structure prediction programs that apply to two datasets of RNA with known secondary structures, which include both pseudoknotted and non-pseudoknotted sequences, as well as a family of viral genome RNAs whose structures have not been predicted before. Our modularized MapReduce framework based on Hadoop allows us to study the problem in a parallel and robust environment. On average, the maximum accuracy retention values are larger than one for our chunking methods and the seven prediction programs over 50 non-pseudoknotted sequences, meaning that the secondary structure predicted using chunking is more similar to the real structure than the secondary structure predicted by using the whole sequence. We observe similar results for the 23 pseudoknotted sequences, except for the NUPACK program using the centered chunking method. The performance analysis for 14 long RNA sequences from the Nodaviridae virus family outlines how the coarse-grained mapping of chunking and predictions in the MapReduce framework exhibits shorter turnaround times for short RNA sequences. However, as the lengths of

  15. Reduced stability of mRNA secondary structure near the translation-initiation site in dsDNA viruses

    OpenAIRE

    Wilke Claus O; Zhou Tong

    2011-01-01

    Abstract Background Recent studies have demonstrated a selection pressure for reduced mRNA secondary-structure stability near the start codon of coding sequences. This selection pressure can be observed in bacteria, archaea, and eukaryotes, and is likely caused by the requirement of efficient translation initiation in cellular organism. Results Here, we surveyed the complete genomes of 650 dsDNA virus strains for signals of reduced stability of mRNA secondary structure near the start codon. O...

  16. Secondary Airflow Structure around Clustered Shrubs and Its Significance for Vegetated Dune Evolution

    Science.gov (United States)

    Luo, Wanyin; Dong, Zhibao; Qian, Guangqiang; Lu, Junfeng

    2016-04-01

    Shrubs have an important significance in aeolian processes due to their disturbance of the local airflow. In the formation of vegetated dunes, there is an iterative interaction between shrub geometry, the structure of the secondary airflow, and the interaction between neighboring shrubs. Understanding the dynamics of vegetated dunes thus requires an insight into the airflow fields around shrubs. Based on aerodynamic and aeolian sand physics theory, this project measured the complex secondary flow field and aeolian sand deposition pattern around single and cluster shrubs with varied densities (i.e., 0.05, 0.08, 0.15, 0.20) and gap ratios (the ratio of the gap spacing between the shrub models to the center-to-center distance for the shrub models, ranged from 1.1 to 1.8 with side-by-side arrangement and 1.2 to 4.3 with tandem arrangement) using the particle image velocimetry system through wind tunnle simulation. The relationship between the secondary airflow structure and the shrub's porosity and arrangement was analyzed quantitatively. Research results revealed that porosity (density) is the key parameter to affect the flow patterns around single shrub. Compared to solid obstacles, bleed flow through the shrubs has great influence on the secondary airflow patterns around itself. Under cluster modes, the distance between two adjacent shrubs has great influence on flow field structures around them. The flow patterns around two side-by-side arranged shrubs can be classified into three kinds of modes, that is: single-bluff-body, biased flow pattern and parallel vortex streets. The flow patterns around two tandem arranged shrubs can be classified into three regimes, that is: the extended body regime, reattachment regime and co-shedding regime. The "shadow zone" with low velocity in the lee of shrubs is the optimal position for sand deposition, but its form, size and orientation would varied with the shrub porosity and gap ratio between them. With the increase of the gap

  17. Secondary structure models of 18S and 28S rRNAs of the true bugs based on complete rDNA sequences of Eurydema maracandica Oshanin, 1871 (Heteroptera, Pentatomidae)

    Science.gov (United States)

    Yu, Shasha; Wang, Yanhui; Rédei, Dávid; Xie, Qiang; Bu, Wenjun

    2013-01-01

    Abstract The sequences of 18S and 28S rDNAs have been used as molecular markers to resolve phylogenetic relationships of Heteroptera for two decades. The complete sequences of 18S rDNAs have been used in many studies, while in most studies only partial sequences of 28S rDNAs have been used due to technical difficulties of amplifying the complete lengths. In this study, we amplified the complete 18S and 28S rDNA sequences of Eurydema maracandica Oshanin, 1871, and reconstructed the secondary structure models of the corresponding rRNAs. In addition, and more importantly, all of the length variable regions of 18S rRNA were compared among 37 families of Heteroptera based on 140 sequences, and the D3 region of 28S rRNA was compared among 51 families based on 84 sequences. It was found that 8 length variable regions could potentially serve as molecular synapomorphies for some monophyletic groups. Therefore discoveries of more molecular synapomorphies for specific clades can be anticipated from amplification of complete 18S and 28S rDNAs of more representatives of Heteroptera. PMID:24039531

  18. Vibrational spectroscopic studies on fibrinogen adsorption at polystyrene/protein solution interfaces: hydrophobic side chain and secondary structure changes.

    Science.gov (United States)

    Wang, Jie; Chen, Xiaoyun; Clarke, Matthew L; Chen, Zhan

    2006-03-16

    Structural changes of fibrinogen after adsorption to polystyrene (PS) were examined at the PS/protein solution interface in situ using sum frequency generation (SFG) vibrational spectroscopy and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). Different behaviors of hydrophobic side chains and secondary structures of adsorbed fibrinogen molecules have been observed. Our results indicate that upon adsorption, the hydrophobic PS surface induces fast structural changes of fibrinogen molecules by aligning some hydrophobic side chains in fibrinogen so that they face to the surface. Such structural changes of fibrinogen hydrophobic side chains are local changes and do not immediately induce significant changes of the protein secondary structures. Our research also shows that the interactions between adsorbed fibrinogen and the PS surface can induce significant changes of protein secondary structures or global conformations which occur on a much longer time scale.

  19. Quaternion-based definition of protein secondary structure straightness and its relationship to Ramachandran angles.

    Science.gov (United States)

    Hanson, Robert M; Kohler, Daniel; Braun, Steven G

    2011-07-01

    We describe here definitions of "local helical axis" and "straightness" that are developed using a simple quaternion-based analysis of protein structure without resort to least-squares fitting. As part of this analysis, it is shown how quaternion differences can be visualized to depict accurately the local helical axis relating any two adjacent amino acid residues in standard, nonidealized proteins. Three different options for the definition of amino acid residue orientation in terms of quaternion frames are described. Two of these, the "C(α) frame" and the "P frame," are shown to be correlated strongly with a simple approximate measure derived solely from Ramachandran angles. The relationship between quaternion-based straightness and recognized DSSP-derived secondary structure motifs is discussed. Copyright © 2011 Wiley-Liss, Inc.

  20. Perturbation of the Secondary Structure of the Scrapie Prion Protein Under Conditions that Alter Infectivity

    Science.gov (United States)

    Gasset, Maria; Baldwin, Michael A.; Fletterick, Robert J.; Prusiner, Stanley B.

    1993-01-01

    Limited proteolysis of the scrapie prion protein (PrPSc) generates PrP 27-30, which polymerizes into amyloid. By attenuated total reflection-Fourier transform infrared spectroscopy, PrP 27-30 polymers contained 54% β-sheet, 25% α-helix, 10% turns, and 11% random coil; dispersion into detergent-lipid-protein-complexes preserved infectivity and secondary structure. Almost 60% of the β-sheet was low-frequency infrared-absorbing, reflecting intermolecular aggregation. Decreased low-frequency β-sheet and increased turn content were found after SDS/PAGE, which disassembled the amyloid polymers, denatured PrP 27-30, and diminished scrapie infectivity. Acid-induced transitions were reversible, whereas alkali produced an irreversible transition centered at pH 10 under conditions that diminished infectivity. Whether PrPSc synthesis involves a transition in the secondary structure of one or more domains of the cellular prion protein from α-helical, random coil, or turn into β-sheet remains to be established.

  1. Evolutionary conservation of sequence and secondary structures inCRISPR repeats

    Energy Technology Data Exchange (ETDEWEB)

    Kunin, Victor; Sorek, Rotem; Hugenholtz, Philip

    2006-09-01

    Clustered Regularly Interspaced Palindromic Repeats (CRISPRs) are a novel class of direct repeats, separated by unique spacer sequences of similar length, that are present in {approx}40% of bacterial and all archaeal genomes analyzed to date. More than 40 gene families, called CRISPR-associated sequences (CAS), appear in conjunction with these repeats and are thought to be involved in the propagation and functioning of CRISPRs. It has been proposed that the CRISPR/CAS system samples, maintains a record of, and inactivates invasive DNA that the cell has encountered, and therefore constitutes a prokaryotic analog of an immune system. Here we analyze CRISPR repeats identified in 195 microbial genomes and show that they can be organized into multiple clusters based on sequence similarity. All individual repeats in any given cluster were inferred to form characteristic RNA secondary structure, ranging from non-existent to pronounced. Stable secondary structures included G:U base pairs and exhibited multiple compensatory base changes in the stem region, indicating evolutionary conservation and functional importance. We also show that the repeat-based classification corresponds to, and expands upon, a previously reported CAS gene-based classification including specific relationships between CRISPR and CAS subtypes.

  2. Compensatory mutations cause excess of antagonistic epistasis in RNA secondary structure folding.

    Science.gov (United States)

    Wilke, Claus O; Lenski, Richard E; Adami, Christoph

    2003-02-05

    The rate at which fitness declines as an organism's genome accumulates random mutations is an important variable in several evolutionary theories. At an intuitive level, it might seem natural that random mutations should tend to interact synergistically, such that the rate of mean fitness decline accelerates as the number of random mutations is increased. However, in a number of recent studies, a prevalence of antagonistic epistasis (the tendency of multiple mutations to have a mitigating rather than reinforcing effect) has been observed. We studied in silico the net amount and form of epistatic interactions in RNA secondary structure folding by measuring the fraction of neutral mutants as a function of mutational distance d. We found a clear prevalence of antagonistic epistasis in RNA secondary structure folding. By relating the fraction of neutral mutants at distance d to the average neutrality at distance d, we showed that this prevalence derives from the existence of many compensatory mutations at larger mutational distances. Our findings imply that the average direction of epistasis in simple fitness landscapes is directly related to the density with which fitness peaks are distributed in these landscapes.

  3. Compensatory mutations cause excess of antagonistic epistasis in RNA secondary structure folding

    Directory of Open Access Journals (Sweden)

    Adami Christoph

    2003-02-01

    Full Text Available Background The rate at which fitness declines as an organism's genome accumulates random mutations is an important variable in several evolutionary theories. At an intuitive level, it might seem natural that random mutations should tend to interact synergistically, such that the rate of mean fitness decline accelerates as the number of random mutations is increased. However, in a number of recent studies, a prevalence of antagonistic epistasis (the tendency of multiple mutations to have a mitigating rather than reinforcing effect has been observed. Results We studied in silico the net amount and form of epistatic interactions in RNA secondary structure folding by measuring the fraction of neutral mutants as a function of mutational distance d. We found a clear prevalence of antagonistic epistasis in RNA secondary structure folding. By relating the fraction of neutral mutants at distance d to the average neutrality at distance d, we showed that this prevalence derives from the existence of many compensatory mutations at larger mutational distances. Conclusions Our findings imply that the average direction of epistasis in simple fitness landscapes is directly related to the density with which fitness peaks are distributed in these landscapes.

  4. 1H and 15N NMR resonance assignments and secondary structure of titin type I domains

    Energy Technology Data Exchange (ETDEWEB)

    Muhle-Goll, Claudia; Nilges, Michael; Pastore, Annalisa [European Molecular Biology Laboratory (Germany)

    1997-01-15

    Titin/connect in is a giant muscle protein with a highly modular architecture consisting of multiple repeats of two sequence motifs, named type I and type II. Type I modules have been suggested to be intracellular members of the fibronectin type III (Fn3) domain family. Along the titin sequence they are exclusively present in the region of the molecule located in the sarcomere A-band. This region has been shown to interact with myosin and C-protein. One of the most noticeable features of type I modules is that they are particularly rich in semiconserved prolines, since these residues account for about 8% of their sequence. We have determined the secondary structure of a representative type I domain (A71) by 15N and 1HNMR. We show that the type I domains of titin have the Fn3 fold as proposed, consisting of a three- and a four-stranded {beta}-sheet. When the two sheets are placed on top of each other to form the {beta}-sandwich characteristic of the Fn3 fold, 8 out of 10 prolines are found on the same side of the molecule and form an exposed hydrophobic patch. This suggests that the semiconserved prolines might be relevant for the function of type I modules, providing a surface for binding to other A-band proteins. The secondary structure of A71 was structurally aligned to other extracellular Fn3 modules of known 3D structure. The alignment shows that titin type I modules have closest similarity to the first Fn3 domain of Drosophila neuroglian.

  5. Direct visualization of secondary structures of F-actin by electron cryomicroscopy.

    Science.gov (United States)

    Fujii, Takashi; Iwane, Atsuko H; Yanagida, Toshio; Namba, Keiichi

    2010-10-07

    F-actin is a helical assembly of actin, which is a component of muscle fibres essential for contraction and has a crucial role in numerous cellular processes, such as the formation of lamellipodia and filopodia, as the most abundant component and regulator of cytoskeletons by dynamic assembly and disassembly (from G-actin to F-actin and vice versa). Actin is a ubiquitous protein and is involved in important biological functions, but the definitive high-resolution structure of F-actin remains unknown. Although a recent atomic model well reproduced X-ray fibre diffraction intensity data from a highly oriented liquid-crystalline sol specimen, its refinement without experimental phase information has certain limitations. Direct visualization of the structure by electron cryomicroscopy, however, has been difficult because it is relatively thin and flexible. Here we report the F-actin structure at 6.6 Å resolution, made obtainable by recent advances in electron cryomicroscopy. The density map clearly resolves all the secondary structures of G-actin, such as α-helices, β-structures and loops, and makes unambiguous modelling and refinement possible. Complex domain motions that open the nucleotide-binding pocket on F-actin formation, specific D-loop and terminal conformations, and relatively tight axial but markedly loose interprotofilament interactions hydrophilic in nature are revealed in the F-actin model, and all seem to be important for dynamic functions of actin.

  6. Short Oligonucleotides Aligned in Stretched Humid Matrix: Secondary DNA Structure in Poly(vinyl alcohol) Environment

    KAUST Repository

    Hanczyc, Piotr

    2012-04-24

    We report that short, synthetic, double- as well as single-stranded DNA can be aligned in stretched humid poly(vinyl alcohol) (PVA) matrix, and the secondary structure (nucleobase orientation) can be characterized with linear dichroism (LD) spectroscopy. Oligonucleotides of lengths varying between 10 (3.4 nm) and 60 bases (20.4 nm) were investigated with respect to structural properties in the gel-like polymer environment. The DNA conformation as a function of relative humidity reveals a strong dependence of helical structure of DNA on PVA hydration level, results of relevance for nanotechnical studies of DNA-based supramolecular systems. Also, the PVA gel could provide possibilities to test models for nucleic acid interactions and distribution in cell contexts, including structural stability of genetic material in the cell and PVA-packaging for gene delivery. A method by which duplex oligonucleotides, with sequences designed to provide specific binding sites, become amenable to polarized-light spectroscopy opens up new possibilities for studying structure in DNA complexes with small adduct molecules as well as proteins. © 2012 American Chemical Society.

  7. Predicting protein folding pathways at the mesoscopic level based on native interactions between secondary structure elements

    Directory of Open Access Journals (Sweden)

    Sze Sing-Hoi

    2008-07-01

    Full Text Available Abstract Background Since experimental determination of protein folding pathways remains difficult, computational techniques are often used to simulate protein folding. Most current techniques to predict protein folding pathways are computationally intensive and are suitable only for small proteins. Results By assuming that the native structure of a protein is known and representing each intermediate conformation as a collection of fully folded structures in which each of them contains a set of interacting secondary structure elements, we show that it is possible to significantly reduce the conformation space while still being able to predict the most energetically favorable folding pathway of large proteins with hundreds of residues at the mesoscopic level, including the pig muscle phosphoglycerate kinase with 416 residues. The model is detailed enough to distinguish between different folding pathways of structurally very similar proteins, including the streptococcal protein G and the peptostreptococcal protein L. The model is also able to recognize the differences between the folding pathways of protein G and its two structurally similar variants NuG1 and NuG2, which are even harder to distinguish. We show that this strategy can produce accurate predictions on many other proteins with experimentally determined intermediate folding states. Conclusion Our technique is efficient enough to predict folding pathways for both large and small proteins at the mesoscopic level. Such a strategy is often the only feasible choice for large proteins. A software program implementing this strategy (SSFold is available at http://faculty.cs.tamu.edu/shsze/ssfold.

  8. Resonance assignments and secondary structure of apolipoprotein E C-terminal domain in DHPC micelles.

    Science.gov (United States)

    Lo, Chi-Jen; Chyan, Chia-Lin; Chen, Yi-Chen; Chang, Chi-Fon; Huang, Hsien-Bin; Lin, Ta-Hsien

    2015-04-01

    Human apolipoprotein E (apoE) has been known to play a key role in the transport of plasma cholesterol and lipoprotein metabolism. It is an apolipoprotein of 299 amino acids with a molecular mass, ~34 kDa. ApoE has three major isoforms, apoE2, apoE3, and apoE4 which differ only at residue 112 or 158. ApoE consists of two independently folded domains (N-terminal and C-terminal domain) separated by a hinge region. The N-terminal domain and C-terminal domain of apoE are responsible for the binding to receptor and to lipid, respectively. Since the high resolution structures of apoE in lipids are still unavailable to date, we therefore aim to resolve the structures in lipids by NMR. Here, we reported the resonance assignments and secondary structure distribution of the C-terminal domain of wild-type human apoE (residue 195-299) in the micelles formed by dihexanoylphosphatidylcholine. Our results may provide a novel structural model of apoE in micelles and may shed new light on the molecular mechanisms underlying the apoE related biological processes.

  9. Probing insulin's secondary structure after entrapment into alginate/chitosan nanoparticles.

    Science.gov (United States)

    Sarmento, B; Ferreira, D C; Jorgensen, L; van de Weert, M

    2007-01-01

    The aim of the present study was to probe the structural integrity of insulin after being entrapped into chitosan/alginate nanoparticles produced by ionotropic polyelectrolyte pre-gelation. By manipulating the alginate:chitosan mass ratio and the pH during nanoparticle production, desired nanoparticles with a mean size of 850 (+/-88)nm and insulin association efficiency of 81 (+/-2)% were obtained. Insulin secondary structure was assessed by Fourier transform infrared (FTIR) and circular dichroism (CD) after entrapment into nanoparticles and after release from the particles under gastrointestinal simulated conditions. FTIR second-derivative spectra and area-overlap compared to an insulin standard confirmed that no significant conformational changes of insulin occurred in terms of alpha-helix and beta-sheet content. Far-UV-CD spectra corroborated the preservation of insulin structure during the nanoparticle production procedure. The presented nanoparticulate system is a promising carrier for insulin oral delivery since it preserves insulin structure and therefore also, potentially, its bioactivity.

  10. Hydroxide-bridged dicopper complexes: the influence of secondary coordination sphere on structure and catecholase activity.

    Science.gov (United States)

    Bansal, Deepak; Gupta, Rajeev

    2017-04-05

    Amide-based ligands (H2L(1-6)) with assorted functional groups appended to them have been used for the synthesis of dicopper(ii) complexes 1-6 having a Cu(μ-OH)Cu core. The crystal structures of 1-6 show that while every Cu(ii) ion is ligated within the N3 pincer cavity of a potentially multidentate ligand, two Cu(ii) centers are bridged by a hydroxide group. Notably, the Cu(μ-OH)Cu core is encased within the secondary coordination sphere intricately created by the appended groups. While complexes 1 and 2 exhibit the presence of an H-bond acceptor in the proximity of the Cu(μ-OH)Cu core, complexes 3 and 4 display the occurrence of both the H-bond donor as well as H-bond acceptor groups in the vicinity of the Cu(μ-OH)Cu core. In contrast, complexes 5 and 6 present modified secondary coordination spheres around the Cu(μ-OH)Cu core with limited H-bonding interacting groups in 5 and no such groups in 6. We show that the extent of H-bonding by the appended groups modulates not only the Cu-OH bond distance, Cu(μ-OH)Cu angle and Cu-Cu separation but also the Cu(2+)/Cu(+) redox potential. All six complexes were utilized for their ability to oxidize 3,5-di-tert-butylcatechol, and the catecholase activity results have been correlated to the secondary coordination sphere created by the appended groups in all six complexes.

  11. 3x2 Classroom Goal Structures, Motivational Regulations, Self-Concept, and Affectivity in Secondary School.

    Science.gov (United States)

    Méndez-Giménez, Antonio; Cecchini-Estrada, José-Antonio; Fernández-Río, Javier; Prieto Saborit, José Antonio; Méndez-Alonso, David

    2017-09-20

    The main objective was to analyze relationships and predictive patterns between 3x2 classroom goal structures (CGS), and motivational regulations, dimensions of self-concept, and affectivity in the context of secondary education. A sample of 1,347 secondary school students (56.6% young men, 43.4% young women) from 10 different provinces of Spain agreed to participate (M age = 13.43, SD = 1.05). Hierarchical regression analyses indicated the self-approach CGS was the most adaptive within the spectrum of self-determination, followed by the task-approach CGS. The other-approach CGS had an ambivalent influence on motivation. Task-approach and self-approach CGS predicted academic self-concept (p affect was predicted by all three approach-oriented CGS's (p affect was predicted by other-approach (positively) and self-approach (negatively) CGS (p < .001; p < .05, respectively; R 2 = .028). These results expand the 3x2 achievement goal framework to include environmental factors, and reiterate that teachers should focus on raising levels of self- and task-based goals for students in their classes.

  12. Combining sequence-based prediction methods and circular dichroism and infrared spectroscopic data to improve protein secondary structure determinations

    Directory of Open Access Journals (Sweden)

    Lees Jonathan G

    2008-01-01

    Full Text Available Abstract Background A number of sequence-based methods exist for protein secondary structure prediction. Protein secondary structures can also be determined experimentally from circular dichroism, and infrared spectroscopic data using empirical analysis methods. It has been proposed that comparable accuracy can be obtained from sequence-based predictions as from these biophysical measurements. Here we have examined the secondary structure determination accuracies of sequence prediction methods with the empirically determined values from the spectroscopic data on datasets of proteins for which both crystal structures and spectroscopic data are available. Results In this study we show that the sequence prediction methods have accuracies nearly comparable to those of spectroscopic methods. However, we also demonstrate that combining the spectroscopic and sequences techniques produces significant overall improvements in secondary structure determinations. In addition, combining the extra information content available from synchrotron radiation circular dichroism data with sequence methods also shows improvements. Conclusion Combining sequence prediction with experimentally determined spectroscopic methods for protein secondary structure content significantly enhances the accuracy of the overall results obtained.

  13. Impact of Microscale and Pilot-Scale Freeze-Drying on Protein Secondary Structures: Sucrose Formulations of Lysozyme and Catalase.

    Science.gov (United States)

    Peters, Björn-Hendrik; Leskinen, Jari T T; Molnár, Ferdinand; Ketolainen, Jarkko

    2015-11-01

    Microscale (MS) freeze-drying offers rapid process cycles for early-stage formulation development. The effects of the MS approach on the secondary structures of two model proteins, lysozyme and catalase, were compared with pilot-scale (PS) vial freeze-drying. The secondary structures were assessed by attenuated total reflection Fourier transformed infrared spectroscopy. Formulations were made with increasing sucrose-protein ratios. Freeze-drying protocols involved regular cooling without thermal treatment and annealing with MS and PS equipment, and cooling rate variations with the MS. Principal component analysis of smoothed second-derivative amide I spectra revealed sucrose-protein ratio-dependent shifts toward α-helical structures. Transferability of sucrose-protein formulations from MS to PS vial freeze-drying was evidenced at regular cooling rates. Local differences in protein secondary structures between the bottom and top of sucrose-catalase samples could be detected at the sucrose-catalase ratios of 1 and 2, this being related to the initial filling height and ice crystal morphology. Annealing revealed temperature, protein, formulation, and sample location-dependent effects influencing surface morphology at the top, or causing protein secondary structure perturbation at the bottom. With the MS approach, protein secondary structure differences at different cooling rates could be detected for sucrose-lysozyme samples at the sucrose-lysozyme ratio of 1. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  14. Structural features of helical secondary structures and leucine-rich repeat superhelix in proteins as revealed by HELFIT analyses

    Science.gov (United States)

    Matsushima, Norio; Enkhbayar, Purevjav

    2012-09-01

    The HELFIT program determines the helical parameters - pitch, residues per turn (n), radius, and handedness - and p = rmsd / (N - 1)1/2 estimating helical regularity, where "rmsd" is the root mean square deviation from the best fit helix or superhelix and "N" is helix/superhelix length. Helical secondary structures - α-helix and 310-helix - and solenoid structures of leucine rich repeats (LRRs) in The Protein Data Bank (PDB) were analyzed by the HELFIT program. The results indicate that the definition of 310-helices in terms of average, uniform dihedral angles is not appropriate and that it is inherently unstable for a polypeptide to form an extended, regular 310-helix. The 310-helices observed in proteins are better referred to parahelices. A modification of the α-helix, termed the ω-helix, that has four residues in one turn of a helix, has been identified only in synthetic polypeptides. The results also demonstrate that the right-handed ω-helix occur really in proteins. The solenoid structures of LRR domains in brasinosteroid insensitive 1 (BRI1), internalin J (InlJ), and internalin A (InlA) are well represented by a superhelix rather than by a circular arc.

  15. Underlying Structure of E-Learning Readiness among Palestinian Secondary School Teachers

    Directory of Open Access Journals (Sweden)

    Trayek Fuad A.A.

    2016-01-01

    Full Text Available This paper reports on the results of an exploratory factor analysis procedure applied on the e-learning readiness data obtained from a survey of four hundred and seventy-five (N = 475 teachers from secondary schools in Nablus, Palestine. The data were collected using a 23-item, self-developed Likert questionnaire measuring e-learning readiness based on Chapnick’s conception of the construct. Principal axis factoring (PAF with Promax rotation applied on the data extracted four distinct factors supporting four of Chapnick’s e-learning readiness dimensions, namely technological, psychological, infrastructure, and equipment readiness. Together these four dimensions explained 56% of the variance. A reliability analysis produced high internal consistency estimates ranging between .81 (equipment readiness and .91 (technological readiness for the extracted factor structure. These findings provide sound empirical support for the construct validity of the items and for the existence of these four factors that measure e-learning readiness.

  16. Modeling of a New Structure of Precision Air Conditioning System Using Secondary Condenser for Rh Regulation

    Directory of Open Access Journals (Sweden)

    Aries Subiantoro

    2012-05-01

    Full Text Available A dynamic mathematical model for a new structure of precision air conditioning (PAC has been developed. The proposed PAC uses an additional secondary condenser for relative humidity regulation compared to a basic refrigeration system. The work mechanism for this system and a vapour-compression cycle process of the system are illustrated using psychrometric chart and pressure-enthalpy diagram. A non-linear system model is derived based on the conservation of mass and energy balance principles and then linearized at steady state operating point for developing a 8th-order state space model suited for multivariable controller design. The quality of linearized model is analyzed in terms of transient response, controllability, observability, and interaction between input-output variables. The developed model is verified through simulation showing its ability for imitating the nonlinear behavior and the interaction of input-output variables.

  17. Examining the dimensional structure models of secondary traumatic stress based on DSM-5 symptoms.

    Science.gov (United States)

    Mordeno, Imelu G; Go, Geraldine P; Yangson-Serondo, April

    2017-02-01

    Latent factor structure of Secondary Traumatic Stress (STS) has been examined using Diagnostic Statistic Manual-IV (DSM-IV)'s Posttraumatic Stress Disorder (PTSD) nomenclature. With the advent of Diagnostic Statistic Manual-5 (DSM-5), there is an impending need to reexamine STS using DSM-5 symptoms in light of the most updated PTSD models in the literature. The study investigated and determined the best fitted PTSD models using DSM-5 PTSD criteria symptoms. Confirmatory factor analysis (CFA) was conducted to examine model fit using the Secondary Traumatic Stress Scale in 241 registered and practicing Filipino nurses (166 females and 75 males) who worked in the Philippines and gave direct nursing services to patients. Based on multiple fit indices, the results showed the 7-factor hybrid model, comprising of intrusion, avoidance, negative affect, anhedonia, externalizing behavior, anxious arousal, and dysphoric arousal factors has excellent fit to STS. This model asserts that: (1) hyperarousal criterion needs to be divided into anxious and dysphoric arousal factors; (2) symptoms characterizing negative and positive affect need to be separated to two separate factors, and; (3) a new factor would categorize externalized, self-initiated impulse and control-deficit behaviors. Comparison of nested and non-nested models showed Hybrid model to have superior fit over other models. The specificity of the symptom structure of STS based on DSM-5 PTSD criteria suggests having more specific interventions addressing the more elaborate symptom-groupings that would alleviate the condition of nurses exposed to STS on a daily basis. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Engineered, highly reactive substrates of microbial transglutaminase enable protein labeling within various secondary structure elements.

    Science.gov (United States)

    Rachel, Natalie M; Quaglia, Daniela; Lévesque, Éric; Charette, André B; Pelletier, Joelle N

    2017-11-01

    Microbial transglutaminase (MTG) is a practical tool to enzymatically form isopeptide bonds between peptide or protein substrates. This natural approach to crosslinking the side-chains of reactive glutamine and lysine residues is solidly rooted in food and textile processing. More recently, MTG's tolerance for various primary amines in lieu of lysine have revealed its potential for site-specific protein labeling with aminated compounds, including fluorophores. Importantly, MTG can label glutamines at accessible positions in the body of a target protein, setting it apart from most labeling enzymes that react exclusively at protein termini. To expand its applicability as a labeling tool, we engineered the B1 domain of Protein G (GB1) to probe the selectivity and enhance the reactivity of MTG toward its glutamine substrate. We built a GB1 library where each variant contained a single glutamine at positions covering all secondary structure elements. The most reactive and selective variants displayed a >100-fold increase in incorporation of a recently developed aminated benzo[a]imidazo[2,1,5-cd]indolizine-type fluorophore, relative to native GB1. None of the variants were destabilized. Our results demonstrate that MTG can react readily with glutamines in α-helical, β-sheet, and unstructured loop elements and does not favor one type of secondary structure. Introducing point mutations within MTG's active site further increased reactivity toward the most reactive substrate variant, I6Q-GB1, enhancing MTG's capacity to fluorescently label an engineered, highly reactive glutamine substrate. This work demonstrates that MTG-reactive glutamines can be readily introduced into a protein domain for fluorescent labeling. © 2017 The Protein Society.

  19. Resolving detailed molecular structures in complex organic mixtures and modeling their secondary organic aerosol formation

    Science.gov (United States)

    Goodman-Rendall, Kevin A. S.; Zhuang, Yang R.; Amirav, Aviv; Chan, Arthur W. H.

    2016-03-01

    Characterization of unresolved complex mixtures (UCMs) remains an ongoing challenge towards developing detailed and accurate inputs for modeling secondary organic aerosol (SOA) formation. Traditional techniques based on gas chromatography/electron impact-mass spectrometry induce excessive fragmentation, making it difficult to speciate and quantify isomers precisely. The goal of this study is to identify individual organic isomers by gas chromatography/mass spectrometry with supersonic molecular beam (SMB-GC/MS, also known as GC/MS with Cold EI) and to incorporate speciated isomers into an SOA model that accounts for the specific structures elucidated. Two samples containing atmospherically relevant UCMs are analyzed. The relative isomer distributions exhibit remarkably consistent trends across a wide range of carbon numbers. Constitutional isomers of different alkanes are speciated and individually quantified as linear, branched - for the first time by position of branching - multiply branched, or unsaturated - by degree of ring substitution and number of rings. Relative amounts of exact molecular structures are used as input parameters in an SOA box model to study the effects of molecular structures on SOA yields and volatility evolution. Highly substituted cyclic, mono-substituted cyclic, and linear species have the highest SOA yields while branched alkanes formed the least SOA. The rate of functionalization of a representative UCM is found to be in agreement with current volatility basis set (VBS) parameterizations based on detailed knowledge of composition and known oxidation mechanisms, confirming the validity of VBS parameters currently used in air quality models.

  20. Rigidity, secondary structure, and the universality of the boson peak in proteins.

    Science.gov (United States)

    Perticaroli, Stefania; Nickels, Jonathan D; Ehlers, Georg; Sokolov, Alexei P

    2014-06-17

    Complementary neutron- and light-scattering results on nine proteins and amino acids reveal the role of rigidity and secondary structure in determining the time- and lengthscales of low-frequency collective vibrational dynamics in proteins. These dynamics manifest in a spectral feature, known as the boson peak (BP), which is common to all disordered materials. We demonstrate that BP position scales systematically with structural motifs, reflecting local rigidity: disordered proteins appear softer than α-helical proteins; which are softer than β-sheet proteins. Our analysis also reveals a universal spectral shape of the BP in proteins and amino acid mixtures; superimposable on the shape observed in typical glasses. Uniformity in the underlying physical mechanism, independent of the specific chemical composition, connects the BP vibrations to nanometer-scale heterogeneities, providing an experimental benchmark for coarse-grained simulations, structure/rigidity relationships, and engineering of proteins for novel applications. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  1. Protein secondary structure and orientation in silk as revealed by Raman spectromicroscopy.

    Science.gov (United States)

    Lefèvre, Thierry; Rousseau, Marie-Eve; Pézolet, Michel

    2007-04-15

    Taking advantage of recent advances in polarized Raman microspectroscopy, and based on a rational decomposition of the amide I band, the conformation and orientation of proteins have been determined for cocoon silks of the silkworms Bombyx mori and Samia cynthia ricini and dragline silks of the spiders Nephila clavipes and Nephila edulis. This study distinguished between band components due to beta-sheets, beta-turns, 3(1)-helices, and unordered structure for the four fibers. For B. mori, the beta-sheet content is 50%, which matches the proportion of residues that form the GAGAGS fibroin motifs. For the Nephila dragline and S. c. ricini cocoon, the beta-sheet content (36-37% and 45%, respectively) is higher than the proportion of residues that belong to polyalanine blocks (18% and 42%, respectively), showing that adjacent GGA motifs are incorporated into the beta-sheets. Nephila spidroins contain fewer beta-sheets and more flexible secondary structures than silkworm fibroins. The amorphous polypeptide chains are preferentially aligned parallel to the fiber direction, although their level of orientation is much lower than that of beta-sheets. Overall, the results show that the four silks exhibit a common molecular organization, with mixtures of different amounts of beta-sheets and flexible structures, which are organized with specific orientation levels.

  2. Phosphorylation regulates the secondary structure and function of dentin phosphoprotein peptides

    Energy Technology Data Exchange (ETDEWEB)

    Villarreal-Ramirez, Eduardo; Eliezer, David; Garduño-Juarez, Ramon; Gericke, Arne; Perez-Aguilar, Jose Manuel; Boskey, Adele

    2017-02-01

    Dentin phosphoprotein (DPP) is the most acidic protein in vertebrates and structurally is classified as an intrinsically disordered protein. Functionally, DPP is related to dentin and bone formation, however the specifics of such association remain unknown. Here, we used atomistic molecular dynamics simulations to screen selected binding domains of DPP onto hydroxyapatite (HA), which is one of its important interacting partners. From these results, we selected a functionally relevant peptide, Ace-SSDSSDSSDSSDSSD-NH2 (named P5) and its phosphorylated form (named P5P), for experimental characterization. SAXS experiments indicated that in solution P5 was disordered, possibly in an extended conformation while P5P displayed more compact globular conformations. Circular dichroism and FTIR confirmed that, either in the presence or absence of Ca2 +/HA, P5 adopts a random coil structure, whereas its phosphorylated counterpart, P5P, has a more compact arrangement associated with conformations that display β-sheet and α-helix motifs when bound to HA. In solution, P5 inhibited HA crystal growth, whereas at similar concentrations, P5P stimulated it. These findings suggest that phosphorylation controls the transient formation of secondary and tertiary structure of DPP peptides, and, most likely of DPP itself, which in turn controls HA growth in solution and possibly HA growth in mineralized tissues.

  3. α-Aminoxy Oligopeptides: Synthesis, Secondary Structure, and Cytotoxicity of a New Class of Anticancer Foldamers.

    Science.gov (United States)

    Diedrich, Daniela; Moita, Ana J Rodrigues; Rüther, Anja; Frieg, Benedikt; Reiss, Guido J; Hoeppner, Astrid; Kurz, Thomas; Gohlke, Holger; Lüdeke, Steffen; Kassack, Matthias U; Hansen, Finn K

    2016-12-05

    α-Aminoxy peptides are peptidomimetic foldamers with high proteolytic and conformational stability. To gain an improved synthetic access to α-aminoxy oligopeptides we used a straightforward combination of solution- and solid-phase-supported methods and obtained oligomers that showed a remarkable anticancer activity against a panel of cancer cell lines. We solved the first X-ray crystal structure of an α-aminoxy peptide with multiple turns around the helical axis. The crystal structure revealed a right-handed 28 -helical conformation with precisely two residues per turn and a helical pitch of 5.8 Å. By 2D ROESY experiments, molecular dynamics simulations, and CD spectroscopy we were able to identify the 28 -helix as the predominant conformation in organic solvents. In aqueous solution, the α-aminoxy peptides exist in the 28 -helical conformation at acidic pH, but exhibit remarkable changes in the secondary structure with increasing pH. The most cytotoxic α-aminoxy peptides have an increased propensity to take up a 28 -helical conformation in the presence of a model membrane. This indicates a correlation between the 28 -helical conformation and the membranolytic activity observed in mode of action studies, thereby providing novel insights in the folding properties and the biological activity of α-aminoxy peptides. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Interaction Of Calcium Phosphate Nanoparticles With Human Chorionic Gonadotropin Modifies Secondary And Tertiary Protein Structure

    Directory of Open Access Journals (Sweden)

    Al-Hakeim Hussein K

    2015-12-01

    Full Text Available Calcium phosphate nanoparticles (CaPNP have good biocompatibility and bioactivity inside human body. In this study, the interaction between CaPNP and human chorionic gonadotropin (hCG was analyzed to determine the changes in the protein structure in the presence of CaPNP and the quantity of protein adsorbed on the CaPNP surface. The results showed a significant adsorption of hCG on the CaPNP nanoparticle surface. The optimal fit was achieved using the Sips isotherm equation with a maximum adsorption capacity of 68.23 µg/mg. The thermodynamic parameters, including ∆H° and ∆G°, of the adsorption process are positive, whereas ∆S° is negative. The circular dichroism results of the adsorption of hCG on CaPNP showed the changes in its secondary structure; such changes include the decomposition of α-helix strand and the increase in β-pleated sheet and random coil percentages. Fluorescence study indicated minimal changes in the tertiary structure near the microenvironment of the aromatic amino acids such as tyrosine and phenyl alanine caused by the interaction forces between the CaPNP and hCG protein. The desorption process showed that the quantity of the hCG desorbed significantly increases as temperature increases, which indicates the weak forces between hCG and the surface.

  5. Linker histone partial phosphorylation: effects on secondary structure and chromatin condensation

    Science.gov (United States)

    Lopez, Rita; Sarg, Bettina; Lindner, Herbert; Bartolomé, Salvador; Ponte, Inma; Suau, Pedro; Roque, Alicia

    2015-01-01

    Linker histones are involved in chromatin higher-order structure and gene regulation. We have successfully achieved partial phosphorylation of linker histones in chicken erythrocyte soluble chromatin with CDK2, as indicated by HPCE, MALDI-TOF and Tandem MS. We have studied the effects of linker histone partial phosphorylation on secondary structure and chromatin condensation. Infrared spectroscopy analysis showed a gradual increase of β-structure in the phosphorylated samples, concomitant to a decrease in α-helix/turns, with increasing linker histone phosphorylation. This conformational change could act as the first step in the phosphorylation-induced effects on chromatin condensation. A decrease of the sedimentation rate through sucrose gradients of the phosphorylated samples was observed, indicating a global relaxation of the 30-nm fiber following linker histone phosphorylation. Analysis of specific genes, combining nuclease digestion and qPCR, showed that phosphorylated samples were more accessible than unphosphorylated samples, suggesting local chromatin relaxation. Chromatin aggregation was induced by MgCl2 and analyzed by dynamic light scattering (DLS). Phosphorylated chromatin had lower percentages in volume of aggregated molecules and the aggregates had smaller hydrodynamic diameter than unphosphorylated chromatin, indicating that linker histone phosphorylation impaired chromatin aggregation. These findings provide new insights into the effects of linker histone phosphorylation in chromatin condensation. PMID:25870416

  6. Dynamics of translation by single ribosomes through mRNA secondary structures

    Science.gov (United States)

    Chen, Chunlai; Zhang, Haibo; Broitman, Steven L.; Reiche, Michael; Farrell, Ian; Cooperman, Barry S.; Goldman, Yale E.

    2013-01-01

    During protein synthesis, the ribosome translates nucleotide triplets in single-stranded mRNA into polypeptide sequences. Strong downstream mRNA secondary (2°) structures, which must be unfolded for translation, can slow or even halt protein synthesis. Here we employ single molecule fluorescence resonance energy transfer to determine reaction rates for specific steps within the elongation cycle as the Escherichia coli ribosome encounters stem loop or pseudoknot mRNA 2° structures. Downstream stem-loops containing 100% G-C base pairs decrease the rates of both tRNA translocation within the ribosome and deacylated tRNA dissociation from the ribosomal exit (E) site. Downstream stem-loops or pseudoknots containing both G-C and A-U pairs also decrease the rate of tRNA dissociation, but they have little effect on tRNA translocation rate. Thus, somewhat surprisingly, unfolding of mRNA 2° structures is more closely coupled to E-site tRNA dissociation than to tRNA translocation. PMID:23542154

  7. FPGA accelerator for protein secondary structure prediction based on the GOR algorithm

    Science.gov (United States)

    2011-01-01

    Background Protein is an important molecule that performs a wide range of functions in biological systems. Recently, the protein folding attracts much more attention since the function of protein can be generally derived from its molecular structure. The GOR algorithm is one of the most successful computational methods and has been widely used as an efficient analysis tool to predict secondary structure from protein sequence. However, the execution time is still intolerable with the steep growth in protein database. Recently, FPGA chips have emerged as one promising application accelerator to accelerate bioinformatics algorithms by exploiting fine-grained custom design. Results In this paper, we propose a complete fine-grained parallel hardware implementation on FPGA to accelerate the GOR-IV package for 2D protein structure prediction. To improve computing efficiency, we partition the parameter table into small segments and access them in parallel. We aggressively exploit data reuse schemes to minimize the need for loading data from external memory. The whole computation structure is carefully pipelined to overlap the sequence loading, computing and back-writing operations as much as possible. We implemented a complete GOR desktop system based on an FPGA chip XC5VLX330. Conclusions The experimental results show a speedup factor of more than 430x over the original GOR-IV version and 110x speedup over the optimized version with multi-thread SIMD implementation running on a PC platform with AMD Phenom 9650 Quad CPU for 2D protein structure prediction. However, the power consumption is only about 30% of that of current general-propose CPUs. PMID:21342582

  8. Human-Driven Microbiological Contamination of Benthic and Hyporheic Sediments of an Intermittent Peri-Urban River Assessed from MST and 16S rRNA Genetic Structure Analyses

    Science.gov (United States)

    Marti, Romain; Ribun, Sébastien; Aubin, Jean-Baptiste; Colinon, Céline; Petit, Stéphanie; Marjolet, Laurence; Gourmelon, Michèle; Schmitt, Laurent; Breil, Pascal; Cottet, Marylise; Cournoyer, Benoit

    2017-01-01

    Rivers are often challenged by fecal contaminations. The barrier effect of sediments against fecal bacteria was investigated through the use of a microbial source tracking (MST) toolbox, and by Next Generation Sequencing (NGS) of V5-V6 16S rRNA gene (rrs) sequences. Non-metric multi-dimensional scaling analysis of V5-V6 16S rRNA gene sequences differentiated bacteriomes according to their compartment of origin i.e., surface water against benthic and hyporheic sediments. Classification of these reads showed the most prevalent operating taxonomic units (OTU) to be allocated to Flavobacterium and Aquabacterium. Relative numbers of Gaiella, Haliangium, and Thermoleophilum OTU matched the observed differentiation of bacteriomes according to river compartments. OTU patterns were found impacted by combined sewer overflows (CSO) through an observed increase in diversity from the sewer to the hyporheic sediments. These changes appeared driven by direct transfers of bacterial contaminants from wastewaters but also by organic inputs favoring previously undetectable bacterial groups among sediments. These NGS datasets appeared more sensitive at tracking community changes than MST markers. The human-specific MST marker HF183 was strictly detected among CSO-impacted surface waters and not river bed sediments. The ruminant-specific DNA marker was more broadly distributed but intense bovine pollution was required to detect transfers from surface water to benthic and hyporheic sediments. Some OTU showed distribution patterns in line with these MST datasets such as those allocated to the Aeromonas, Acinetobacter, and Pseudomonas. Fecal indicators (Escherichia coli and total thermotolerant coliforms) were detected all over the river course but their concentrations were not correlated with MST ones. Overall, MST and NGS datasets suggested a poor colonization of river sediments by bovine and sewer bacterial contaminants. No environmental outbreak of these bacterial contaminants was

  9. Human-Driven Microbiological Contamination of Benthic and Hyporheic Sediments of an Intermittent Peri-Urban River Assessed from MST and 16S rRNA Genetic Structure Analyses.

    Science.gov (United States)

    Marti, Romain; Ribun, Sébastien; Aubin, Jean-Baptiste; Colinon, Céline; Petit, Stéphanie; Marjolet, Laurence; Gourmelon, Michèle; Schmitt, Laurent; Breil, Pascal; Cottet, Marylise; Cournoyer, Benoit

    2017-01-01

    Rivers are often challenged by fecal contaminations. The barrier effect of sediments against fecal bacteria was investigated through the use of a microbial source tracking (MST) toolbox, and by Next Generation Sequencing (NGS) of V5-V6 16S rRNA gene (rrs) sequences. Non-metric multi-dimensional scaling analysis of V5-V6 16S rRNA gene sequences differentiated bacteriomes according to their compartment of origin i.e., surface water against benthic and hyporheic sediments. Classification of these reads showed the most prevalent operating taxonomic units (OTU) to be allocated to Flavobacterium and Aquabacterium. Relative numbers of Gaiella, Haliangium, and Thermoleophilum OTU matched the observed differentiation of bacteriomes according to river compartments. OTU patterns were found impacted by combined sewer overflows (CSO) through an observed increase in diversity from the sewer to the hyporheic sediments. These changes appeared driven by direct transfers of bacterial contaminants from wastewaters but also by organic inputs favoring previously undetectable bacterial groups among sediments. These NGS datasets appeared more sensitive at tracking community changes than MST markers. The human-specific MST marker HF183 was strictly detected among CSO-impacted surface waters and not river bed sediments. The ruminant-specific DNA marker was more broadly distributed but intense bovine pollution was required to detect transfers from surface water to benthic and hyporheic sediments. Some OTU showed distribution patterns in line with these MST datasets such as those allocated to the Aeromonas, Acinetobacter, and Pseudomonas. Fecal indicators (Escherichia coli and total thermotolerant coliforms) were detected all over the river course but their concentrations were not correlated with MST ones. Overall, MST and NGS datasets suggested a poor colonization of river sediments by bovine and sewer bacterial contaminants. No environmental outbreak of these bacterial contaminants was

  10. Protein-associated water and secondary structure effect removal of blood proteins from metallic substrates.

    Science.gov (United States)

    Anand, Gaurav; Zhang, Fuming; Linhardt, Robert J; Belfort, Georges

    2011-03-01

    Removing adsorbed protein from metals has significant health and industrial consequences. There are numerous protein-adsorption studies using model self-assembled monolayers or polymeric substrates but hardly any high-resolution measurements of adsorption and removal of proteins on industrially relevant transition metals. Surgeons and ship owners desire clean metal surfaces to reduce transmission of disease via surgical instruments and minimize surface fouling (to reduce friction and corrosion), respectively. A major finding of this work is that, besides hydrophobic interaction adhesion energy, water content in an adsorbed protein layer and secondary structure of proteins determined the access and hence ability to remove adsorbed proteins from metal surfaces with a strong alkaline-surfactant solution (NaOH and 5 mg/mL SDS in PBS at pH 11). This is demonstrated with three blood proteins (bovine serum albumin, immunoglobulin, and fibrinogen) and four transition metal substrates and stainless steel (platinum (Pt), gold (Au), tungsten (W), titanium (Ti), and 316 grade stainless steel (SS)). All the metallic substrates were checked for chemical contaminations like carbon and sulfur and were characterized using X-ray photoelectron spectroscopy (XPS). While Pt and Au surfaces were oxide-free (fairly inert elements), W, Ti, and SS substrates were associated with native oxide. Difference measurements between a quartz crystal microbalance with dissipation (QCM-D) and surface plasmon resonance spectroscopy (SPR) provided a measure of the water content in the protein-adsorbed layers. Hydrophobic adhesion forces, obtained with atomic force microscopy, between the proteins and the metals correlated with the amount of the adsorbed protein-water complex. Thus, the amount of protein adsorbed decreased with Pt, Au, W, Ti and SS, in this order. Neither sessile contact angle nor surface roughness of the metal substrates was useful as predictors here. All three globular proteins

  11. Fine-grained parallel RNAalifold algorithm for RNA secondary structure prediction on FPGA.

    Science.gov (United States)

    Xia, Fei; Dou, Yong; Zhou, Xingming; Yang, Xuejun; Xu, Jiaqing; Zhang, Yang

    2009-01-30

    In the field of RNA secondary structure prediction, the RNAalifold algorithm is one of the most popular methods using free energy minimization. However, general-purpose computers including parallel computers or multi-core computers exhibit parallel efficiency of no more than 50%. Field Programmable Gate-Array (FPGA) chips provide a new approach to accelerate RNAalifold by exploiting fine-grained custom design. RNAalifold shows complicated data dependences, in which the dependence distance is variable, and the dependence direction is also across two dimensions. We propose a systolic array structure including one master Processing Element (PE) and multiple slave PEs for fine grain hardware implementation on FPGA. We exploit data reuse schemes to reduce the need to load energy matrices from external memory. We also propose several methods to reduce energy table parameter size by 80%. To our knowledge, our implementation with 16 PEs is the only FPGA accelerator implementing the complete RNAalifold algorithm. The experimental results show a factor of 12.2 speedup over the RNAalifold (ViennaPackage - 1.6.5) software for a group of aligned RNA sequences with 2981-residue running on a Personal Computer (PC) platform with Pentium 4 2.6 GHz CPU.

  12. Secondary structure and conformational change of mushroom polyphenol oxidase during thermosonication treatment by using FTIR spectroscopy.

    Science.gov (United States)

    Baltacıoğlu, Hande; Bayındırlı, Alev; Severcan, Feride

    2017-01-01

    To understand the conformational changes of mushroom PPO, the secondary structural change of the enzyme during thermosonication treatment at different power (60, 80 and 100%), temperature (20-60°C) and time (0-30min) combinations was investigated by using FTIR spectroscopy and compared with the change in enzyme activity. The enzyme inactivation higher than 99% was obtained at 100% amplitude at 60°C for 10min. FTIR studies showed that marked spectral changes were noted after ultrasound treatment at 20°C. The α-helix and β-sheet contents decreased, while aggregated β-sheet, turns and random coil contents increased as temperature increased up to 60°C during thermosonication treatment for 10min indicating protein denaturation. Aggregated bands located at 1683 and 1616cm(-1) became evident after ultrasound treatment at 40°C. When temperature was lowered back to 25°C, from ultrasound treatment at 60°C, these bands were still observed, indicating the irreversible change in the structure. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. FTIR Study On The Secondary Structure Of Mucin From Mucinous Cystadenoma Of The Ovary

    Science.gov (United States)

    Shen, Keng; Wu, Paochen; Zhou, Weij in; Liu, Fuan; Guo, Hai; Wu, Jinguang

    1989-12-01

    The mucinous cystadenoma, a common benign neoplasm of the ovary, may sometime bring about a fatal outcome known as pseudomyxoma peritonei which is characterized by massive accumulation of mucinous substance in the peritoneal cavity, resulting in extensive adhesions, chronic progressive intestinal obstruction and finally death of the patient. Surgical approach to this condition proves to be a palliative procedure. Repeated operation can only remove part of the geletinous material and reaccumulation of mucus within 1-2 years after the initial surgery is almost a rule. In view of the benign histologic nature of the disease, chemotherapy, either systemic or intraperitoneal, and radiotherapy are generally ineffective in arresting the progression of the pathologic process and preventing the reaccumulation of mucus. Therefore, the only hope lies on the introduction into the peritoneal cavity some agents which may dissolve the accumulated mucin, relieve the intestinal obstruction, and consequently, prolong and even save the life f the patient. Based on this conception, sporadic articles by a few authors(1,2)ap-peared in the literature reporting their clinical experience with different mucolytic agents. However, some blindness would inevitably be involved in such investigations due to the lack of a comprehensive understanding of the chemical structures of the substance. The purpose of the present paper is to report our preliminary results of study of the secondary structures of mucin secreted by this special type of tumor.

  14. Enzyme stability, thermodynamics and secondary structures of α-amylase as probed by the CD spectroscopy.

    Science.gov (United States)

    Kikani, B A; Singh, S P

    2015-11-01

    An amylase of a thermophilic bacterium, Bacillus sp. TSSC-3 (GenBank Number, EU710557) isolated from the Tulsi Shyam hot spring reservoir (Gujarat, India) was purified to the homogeneity in a single step on phenyl sepharose 6FF. The molecular weight of the enzyme was 25kD, while the temperature and pH optima for the enzyme catalysis were 80°C and 7, respectively. The purified enzyme was highly thermostable with broad pH stability and displayed remarkable resistance against surfactants, chelators, urea, guanidine HCl and various solvents as well. The stability and changes in the secondary structure of the enzyme under various extreme conditions were determined by the circular dichroism (CD) spectroscopy. The stability trends and the changes in the α-helices and β-sheets were analyzed by Mean Residual Ellipticity (MRE) and K2D3. The CD data confirmed the structural stability of the enzyme under various harsh conditions, yet it indicated reduced α-helix content and increased β-sheets upon denaturation. The thermodynamic parameters; deactivation rate constant, half-life, changes in entropy, enthalpy, activation energy and Gibb's free energy indicated that the enzyme-substrate reactions were highly stable. The overall profile of the enzyme: high thermostability, alkalitolerance, calcium independent nature, dextrose equivalent values and resistance against chemical denaturants, solvents and surfactants suggest its commercial applications. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. An Archaea 5S rRNA analog is stably expressed in Escherichia coli

    Science.gov (United States)

    Yang, Y.; Fox, G. E.

    1996-01-01

    Mini-genes for 5S-like rRNA were constructed. These genes had a sequence which largely resembles that of the naturally occurring 5S rRNA of a bacterium, Halococcus morrhuae, which phylogenetically belongs to the Archaea. Plasmids carrying the mini-genes were transformed into Escherichia coli (Ec). Ribosomal incorporation was not a prerequisite for stable accumulation of the RNA product. However, only those constructs with a well-base-paired helix I accumulated RNA product. This result strongly implies that this aspect of the structure is likely to be an important condition for stabilizing 5S rRNA-like products. The results are consistent with our current understanding of 5S rRNA processing in Ec. When used in conjunction with rRNA probe technology, the resulting chimeric RNA may be useful as a monitoring tool for genetically engineered microorganisms or naturally occurring organisms that are released into the environment.

  16. Improving prediction of secondary structure, local backbone angles, and solvent accessible surface area of proteins by iterative deep learning.

    Science.gov (United States)

    Heffernan, Rhys; Paliwal, Kuldip; Lyons, James; Dehzangi, Abdollah; Sharma, Alok; Wang, Jihua; Sattar, Abdul; Yang, Yuedong; Zhou, Yaoqi

    2015-06-22

    Direct prediction of protein structure from sequence is a challenging problem. An effective approach is to break it up into independent sub-problems. These sub-problems such as prediction of protein secondary structure can then be solved independently. In a previous study, we found that an iterative use of predicted secondary structure and backbone torsion angles can further improve secondary structure and torsion angle prediction. In this study, we expand the iterative features to include solvent accessible surface area and backbone angles and dihedrals based on Cα atoms. By using a deep learning neural network in three iterations, we achieved 82% accuracy for secondary structure prediction, 0.76 for the correlation coefficient between predicted and actual solvent accessible surface area, 19° and 30° for mean absolute errors of backbone φ and ψ angles, respectively, and 8° and 32° for mean absolute errors of Cα-based θ and τ angles, respectively, for an independent test dataset of 1199 proteins. The accuracy of the method is slightly lower for 72 CASP 11 targets but much higher than those of model structures from current state-of-the-art techniques. This suggests the potentially beneficial use of these predicted properties for model assessment and ranking.

  17. Protein secondary structure prediction from circular dichroism spectra using a self-organizing map with concentration correction.

    Science.gov (United States)

    Hall, Vincent; Sklepari, Meropi; Rodger, Alison

    2014-09-01

    Collecting circular dichroism (CD) spectra for protein solutions is a simple experiment, yet reliable extraction of secondary structure content is dependent on knowledge of the concentration of the protein--which is not always available with accuracy. We previously developed a self-organizing map (SOM), called Secondary Structure Neural Network (SSNN), to cluster a database of CD spectra and use that map to assign the secondary structure content of new proteins from CD spectra. The performance of SSNN is at least as good as other available protein CD structure-fitting algorithms. In this work we apply SSNN to a collection of spectra of experimental samples where there was suspicion that the nominal protein concentration was incorrect. We show that by plotting the normalized root mean square deviation of the SSNN predicted spectrum from the experimental one versus a concentration scaling-factor it is possible to improve the estimate of the protein concentration while providing an estimate of the secondary structure. For our implementation (51 data points 240-190 nm in nm increments) good fits and structure estimates were obtained if the NRMSD (normalized root mean square displacement, RMSE/data range) is <0.03; reasonable for NRMSD <0.05; and variable above this. We also augmented the reference database with 100% helical spectra and truly random coil spectra. © 2014 Wiley Periodicals, Inc.

  18. Comparison of Bacteroides thetaiotaomicron and Escherichia coli 16S rRNA gene expression signals.

    Science.gov (United States)

    Mastropaolo, Matthew D; Thorson, Mary L; Stevens, Ann M

    2009-08-01

    There are barriers to cross-expression of genes between Bacteroides spp. and Escherichia coli. In this study, a lux-based reporter system was developed for Bacteroides and used to compare the promoter structure and function of a Bacteroides thetaiotaomicron 4001 (BT4001) 16S rRNA promoter with those of E. coli in vivo. Analysis of the BT4001 sequences upstream of the 16S rRNA gene revealed the same overall structure known for E. coli 16S rRNA promoters in that there were two promoters separated by approximately 150 bp. However, the BT4001 16S rRNA promoter contains the proposed Bacteroides -7 and -33 consensus sequences instead of the E. coli -10 and -35 consensus sequences. The biological activity of various configurations of the BT4001 16S rRNA promoter was analysed. Experiments pairing the BT4001 16S rRNA promoter with an E. coli RBS, and vice-versa, confirmed that gene expression between the two species is restricted at the level of transcription. In Bacteroides, a difference in translation initiation also appears to limit expression of foreign genes.

  19. Experimental and theoretical study of the vibrational spectra of oligoureas: helical versus β-sheet-type secondary structures.

    Science.gov (United States)

    Cavagnat, Dominique; Claudon, Paul; Fischer, Lucile; Guichard, Gilles; Desbat, Bernard

    2011-04-21

    Ab initio calculations of two oligoureas stabilized in helix and sheet organization have been performed. The hydrogen bond distances were found to be almost the same for both structures. The vibrational assignment of the two oligourea structures and the direction of the transition moment of each vibration have been determined. From these results, and using the experimental isotropic optical index determined for one oligourea, we have established the anisotropic infrared optical files for the two structures. Interestingly, most urea absorptions vibrate in only one principal direction. Also, the shift of the carbonyl band is weaker and inverse to what was reported for corresponding protein secondary structures. Finally, simulations of the Polarization Modulation Infrared Reflection Absorption Spectroscopy (PMIRRAS) and Attenuated Reflection Spectroscopy (ATR) infrared spectra demonstrate the possibility to determine the orientation of the oligoureas in thin or ultrathin films, even if in some cases it may be difficult to unambiguously assign their secondary structure.

  20. Residual structure of Streptococcus mutans biofilm following complete disinfection favors secondary bacterial adhesion and biofilm re-development.

    Directory of Open Access Journals (Sweden)

    Tatsuya Ohsumi

    Full Text Available Chemical disinfection of oral biofilms often leaves biofilm structures intact. This study aimed to examine whether the residual structure promotes secondary bacterial adhesion. Streptococcus mutans biofilms generated on resin-composite disks in a rotating disc reactor were disinfected completely with 70% isopropyl alcohol, and were again cultured in the same reactor after resupplying with the same bacterial solution. Specimens were subjected to fluorescence confocal laser scanning microscopy, viable cell counts and PCR-Invader assay in order to observe and quantify secondarily adhered cells. Fluorescence microscopic analysis, particularly after longitudinal cryosectioning, demonstrated stratified patterns of viable cells on the disinfected biofilm structure. Viable cell counts of test specimens were significantly higher than those of controls, and increased according to the amount of residual structure and culture period. Linear regression analysis exhibited a high correlation between viable and total cell counts. It was concluded that disinfected biofilm structures favored secondary bacterial adhesion.

  1. Imaging the 3D structure of secondary osteons in human cortical bone using phase-retrieval tomography

    Energy Technology Data Exchange (ETDEWEB)

    Arhatari, B D; Peele, A G [Department of Physics, La Trobe University, Victoria 3086 (Australia); Cooper, D M L [Department of Anatomy and Cell Biology, University of Saskatchewan, Saskatoon (Canada); Thomas, C D L; Clement, J G [Melbourne Dental School, University of Melbourne, Victoria 3010 (Australia)

    2011-08-21

    By applying a phase-retrieval step before carrying out standard filtered back-projection reconstructions in tomographic imaging, we were able to resolve structures with small differences in density within a densely absorbing sample. This phase-retrieval tomography is particularly suited for the three-dimensional segmentation of secondary osteons (roughly cylindrical structures) which are superimposed upon an existing cortical bone structure through the process of turnover known as remodelling. The resulting images make possible the analysis of the secondary osteon structure and the relationship between an osteon and the surrounding tissue. Our observations have revealed many different and complex 3D structures of osteons that could not be studied using previous methods. This work was carried out using a laboratory-based x-ray source, which makes obtaining these sorts of images readily accessible.

  2. Teaching Through Interactions in Secondary School Classrooms: Revisiting the Factor Structure and Practical Application of the Classroom Assessment Scoring System–Secondary

    Science.gov (United States)

    Hafen, Christopher A.; Hamre, Bridget K.; Allen, Joseph P.; Bell, Courtney A.; Gitomer, Drew H.; Pianta, Robert C.

    2017-01-01

    Valid measurement of how students’ experiences in secondary school classrooms lead to gains in learning requires a developmental approach to conceptualizing classroom processes. This article presents a potentially useful theoretical model, the Teaching Through Interactions framework, which posits teacher-student interactions as a central driver for student learning and that teacher-student interactions can be organized into three major domains. Results from 1,482 classrooms provide evidence for distinct emotional, organizational, and instructional domains of teacher-student interaction. It also appears that a three-factor structure is a better fit to observational data than alternative one- and two-domain models of teacher-student classroom interactions, and that the three-domain structure is generalizable from 6th through 12th grade. Implications for practitioners, stakeholders, and researchers are discussed. PMID:28232770

  3. Teaching Through Interactions in Secondary School Classrooms: Revisiting the Factor Structure and Practical Application of the Classroom Assessment Scoring System-Secondary.

    Science.gov (United States)

    Hafen, Christopher A; Hamre, Bridget K; Allen, Joseph P; Bell, Courtney A; Gitomer, Drew H; Pianta, Robert C

    2015-06-01

    Valid measurement of how students' experiences in secondary school classrooms lead to gains in learning requires a developmental approach to conceptualizing classroom processes. This article presents a potentially useful theoretical model, the Teaching Through Interactions framework, which posits teacher-student interactions as a central driver for student learning and that teacher-student interactions can be organized into three major domains. Results from 1,482 classrooms provide evidence for distinct emotional, organizational, and instructional domains of teacher-student interaction. It also appears that a three-factor structure is a better fit to observational data than alternative one- and two-domain models of teacher-student classroom interactions, and that the three-domain structure is generalizable from 6th through 12th grade. Implications for practitioners, stakeholders, and researchers are discussed.

  4. Ensembled support vector machines for human papillomavirus risk type prediction from protein secondary structures.

    Science.gov (United States)

    Kim, Sun; Kim, Jeongmi; Zhang, Byoung-Tak

    2009-02-01

    Infection by the human papillomavirus (HPV) is regarded as the major risk factor in the development of cervical cancer. Detection of high-risk HPV is important for understanding its oncogenic mechanisms and for developing novel clinical tools for its diagnosis, treatment, and prevention. Several methods are available to predict the risk types for HPV protein sequences. Nevertheless, no tools can achieve a universally good performance for all domains, including HPV and nor do they provide confidence levels for their decisions. Here, we describe ensembled support vector machines (SVMs) to classify HPV risk types, which assign given proteins into high-, possibly high-, or low-risk type based on their confidence level. Our approach uses protein secondary structures to obtain the differential contribution of subsequences for the risk type, and SVM classifiers are combined with a simple but efficient string kernel to handle HPV protein sequences. In the experiments, we compare our approach with previous methods in accuracy and F1-score, and present the predictions for unknown HPV types, which provides promising results.

  5. Fine-grained parallelism accelerating for RNA secondary structure prediction with pseudoknots based on FPGA.

    Science.gov (United States)

    Xia, Fei; Jin, Guoqing

    2014-06-01

    PKNOTS is a most famous benchmark program and has been widely used to predict RNA secondary structure including pseudoknots. It adopts the standard four-dimensional (4D) dynamic programming (DP) method and is the basis of many variants and improved algorithms. Unfortunately, the O(N(6)) computing requirements and complicated data dependency greatly limits the usefulness of PKNOTS package with the explosion in gene database size. In this paper, we present a fine-grained parallel PKNOTS package and prototype system for accelerating RNA folding application based on FPGA chip. We adopted a series of storage optimization strategies to resolve the "Memory Wall" problem. We aggressively exploit parallel computing strategies to improve computational efficiency. We also propose several methods that collectively reduce the storage requirements for FPGA on-chip memory. To the best of our knowledge, our design is the first FPGA implementation for accelerating 4D DP problem for RNA folding application including pseudoknots. The experimental results show a factor of more than 50x average speedup over the PKNOTS-1.08 software running on a PC platform with Intel Core2 Q9400 Quad CPU for input RNA sequences. However, the power consumption of our FPGA accelerator is only about 50% of the general-purpose micro-processors.

  6. Molecular systematics of Barbatosphaeria (Sordariomycetes): multigene phylogeny and secondary ITS structure.

    Science.gov (United States)

    Réblová, M; Réblová, K; Štěpánek, V

    2015-12-01

    Thirteen morphologically similar strains of barbatosphaeria- and tectonidula-like fungi were studied based on the comparison of cultural and morphological features of sexual and asexual morphs and phylogenetic analyses of five nuclear loci, i.e. internal transcribed spacer rDNA operon (ITS), large and small subunit nuclear ribosomal DNA, β-tubulin, and second largest subunit of RNA polymerase II. Phylogenetic results were supported by in-depth comparative analyses of common core secondary structure of ITS1 and ITS2 in all strains and the identification of non-conserved, co-evolving nucleotides that maintain base pairing in the RNA transcript. Barbatosphaeria is defined as a well-supported monophyletic clade comprising several lineages and is placed in the Sordariomycetes incertae sedis. The genus is expanded to encompass nine species with both septate and non-septate ascospores in clavate, stipitate asci with a non-amyloid apical annulus and non-stromatic ascomata with a long decumbent neck and carbonised wall often covered by pubescence. The asexual morphs are dematiaceous hyphomycetes with holoblastic conidiogenesis belonging to Ramichloridium and Sporothrix types. The morphologically similar Tectonidula, represented by the type species T. hippocrepida, grouped with members of Barbatosphaeria and is transferred to that genus. Four new species are introduced and three new combinations in Barbatosphaeria are proposed. A dichotomous key to species accepted in the genus is provided.

  7. Flammability of self-extinguishing kenaf/ABS nanoclays composite for aircraft secondary structure

    Science.gov (United States)

    Karunakaran, S.; Majid, D. L.; Mohd Tawil, M. L.

    2016-10-01

    This study investigates the flammability properties of kenaf fiber reinforced acrylonitrile butadiene styrene (ABS) with nanoclays composites. Natural fiber is one of the potential materials to be used with thermoplastic as a composite due to its attractive properties such as lightweight and strong. In this paper, flammability properties of this material are evaluated through Underwriters Laboratory 94 Horizontal Burning (UL94 HB), which has been conducted for both controlled and uncontrolled conditions, smoke density and limiting oxygen index tests (LOI). These flammability tests are in compliance with the Federal Aviation Regulation (FAR) requirement. The results from UL94 HB and smoke density tests show that the presence of nanoclays with effective composition of kenaf fiber reinforced ABS has enhanced the burning characteristics of the material by hindering propagation of flame spread over the surface of the material through char formation. Consequently, this decreases the burning rate and produces low amount of smoke during burning. On contrary, through LOI test, this material requires less oxygen to burn when exposed to fire, which hinders the enhancement of burning characteristics. This is due to burning mechanism exhibited by nanoclays that catalyzes barrier formation and flame propagation rate over the surface of the biocomposite material. Overall, these experimental results suggest that this biocomposite material is capable of self-extinguishing and possesses effective fire extinction. The observed novel synergism from the result obtained is promising to be implemented in secondary structures of aircraft with significant benefits such as cost-effective, lightweight and biodegradable self-extinguishing biocomposite.

  8. The structure of interests in different artistic disciplines of secondary school students

    Directory of Open Access Journals (Sweden)

    Ristić Irena J.

    2013-01-01

    Full Text Available The paper deals with the degree of development of interest in arts in young people, and the justifiability of the current tendency of revision and abbreviation of the art curricula in schools. The research is focused on the structure of interests in various artistic disciplines in secondary school students, and the aim is to determine whether the degree of students’ interest depends on the school type, gender and previous experience. The research was conducted on the sample of 555 students from 111 schools, who filled out the questionnaire during one school period. The data were processed by multifactor analysis of variance. There was a higher degree of interest in video and performing arts, which are not present enough in students’ surroundings. The girls showed a higher degree of interest in all disciplines, as well as grammar school students compared to their peers from vocational schools. It was shown that the higher the number of programmes attended, the higher the interest in all forms of art. Young people who were completely inactive showed interest in video arts, which serves as an important guideline in the process of moving and socialising them. The results confirm that youth’s interests and needs are discrepant with what is offered to them. It is necessary to introduce various artistic contents as parts of the curriculum, which would make school an integral part of their life, the part that directly influences the development of creativity and increases responsible participation in the society.

  9. Ribosomal ITS sequences allow resolution of freshwater sponge phylogeny with alignments guided by secondary structure prediction.

    Science.gov (United States)

    Itskovich, Valeria; Gontcharov, Andrey; Masuda, Yoshiki; Nohno, Tsutomu; Belikov, Sergey; Efremova, Sofia; Meixner, Martin; Janussen, Dorte

    2008-12-01

    Freshwater sponges include six extant families which belong to the suborder Spongillina (Porifera). The taxonomy of freshwater sponges is problematic and their phylogeny and evolution are not well understood. Sequences of the ribosomal internal transcribed spacers (ITS1 and ITS2) of 11 species from the family Lubomirskiidae, 13 species from the family Spongillidae, and 1 species from the family Potamolepidae were obtained to study the phylogenetic relationships between endemic and cosmopolitan freshwater sponges and the evolution of sponges in Lake Baikal. The present study is the first one where ITS1 sequences were successfully aligned using verified secondary structure models and, in combination with ITS2, used to infer relationships between the freshwater sponges. Phylogenetic trees inferred using maximum likelihood, neighbor-joining, and parsimony methods and Bayesian inference revealed that the endemic family Lubomirskiidae was monophyletic. Our results do not support the monophyly of Spongillidae because Lubomirskiidae formed a robust clade with E. muelleri, and Trochospongilla latouchiana formed a robust clade with the outgroup Echinospongilla brichardi (Potamolepidae). Within the cosmopolitan family Spongillidae the genera Radiospongilla and Eunapius were found to be monophyletic, while Ephydatia muelleri was basal to the family Lubomirskiidae. The genetic distances between Lubomirskiidae species being much lower than those between Spongillidae species are indicative of their relatively recent radiation from a common ancestor. These results indicated that rDNA spacers sequences can be useful in the study of phylogenetic relationships of and the identification of species of freshwater sponges.

  10. Temperature Effects on Mechanical Properties of Woven Thermoplastic Composites for Secondary Aircraft Structure Applications

    Directory of Open Access Journals (Sweden)

    Wang Yue

    2017-01-01

    Full Text Available The effect of temperature on the mechanical behavior of 8-H satin woven glass fabric/polyethylene sulfide (GF/PPS was investigated in this paper. Static-tensile tests were both conducted on notched and unnotched specimens at typical temperatures (ambient, 95°C and 125°C based on the glass transition temperatures (Tg of the neat resin and composite, their strength and moduli were obtained and compared. The damage patterns of failed specimens of notched and unnotched were examined with the aid of high-definition camera and stereomicroscope. The results of stress-strain relationships showed that the slight nonlinearity of the curves were observed for these two specimens, which was associated with the plastic deformation of localized resin. The damage patterns of notched and unnotched specimens at different temperatures proved that damage and plastic deformation were two simultaneous mechanisms and it was prominent in the notched. It was the overstress accommodation mechanism that led to a relative high strength rentention for the notched and a reduction of the hole sensitivity. The results obtained in this paper indicated that GF/PPS can be used as secondary aircraft structures at elevated temperatures higher than its Tg.

  11. Genomic mid-range inhomogeneity correlates with an abundance of RNA secondary structures

    Directory of Open Access Journals (Sweden)

    Song Jun

    2008-06-01

    Full Text Available Abstract Background Genomes possess different levels of non-randomness, in particular, an inhomogeneity in their nucleotide composition. Inhomogeneity is manifest from the short-range where neighboring nucleotides influence the choice of base at a site, to the long-range, commonly known as isochores, where a particular base composition can span millions of nucleotides. A separate genomic issue that has yet to be thoroughly elucidated is the role that RNA secondary structure (SS plays in gene expression. Results We present novel data and approaches that show that a mid-range inhomogeneity (~30 to 1000 nt not only exists in mammalian genomes but is also significantly associated with strong RNA SS. A whole-genome bioinformatics investigation of local SS in a set of 11,315 non-redundant human pre-mRNA sequences has been carried out. Four distinct components of these molecules (5'-UTRs, exons, introns and 3'-UTRs were considered separately, since they differ in overall nucleotide composition, sequence motifs and periodicities. For each pre-mRNA component, the abundance of strong local SS ( Conclusion We demonstrate that the excess of strong local SS in pre-mRNAs is linked to the little explored phenomenon of genomic mid-range inhomogeneity (MRI. MRI is an interdependence between nucleotide choice and base composition over a distance of 20–1000 nt. Additionally, we have created a public computational resource to support further study of genomic MRI.

  12. Comparative genome structure, secondary metabolite, and effector coding capacity across Cochliobolus pathogens.

    Directory of Open Access Journals (Sweden)

    Bradford J Condon

    Full Text Available The genomes of five Cochliobolus heterostrophus strains, two Cochliobolus sativus strains, three additional Cochliobolus species (Cochliobolus victoriae, Cochliobolus carbonum, Cochliobolus miyabeanus, and closely related Setosphaeria turcica were sequenced at the Joint Genome Institute (JGI. The datasets were used to identify SNPs between strains and species, unique genomic regions, core secondary metabolism genes, and small secreted protein (SSP candidate effector encoding genes with a view towards pinpointing structural elements and gene content associated with specificity of these closely related fungi to different cereal hosts. Whole-genome alignment shows that three to five percent of each genome differs between strains of the same species, while a quarter of each genome differs between species. On average, SNP counts among field isolates of the same C. heterostrophus species are more than 25× higher than those between inbred lines and 50× lower than SNPs between Cochliobolus species. The suites of nonribosomal peptide synthetase (NRPS, polyketide synthase (PKS, and SSP-encoding genes are astoundingly diverse among species but remarkably conserved among isolates of the same species, whether inbred or field strains, except for defining examples that map to unique genomic regions. Functional analysis of several strain-unique PKSs and NRPSs reveal a strong correlation with a role in virulence.

  13. GADIS: Algorithm for designing sequences to achieve target secondary structure profiles of intrinsically disordered proteins.

    Science.gov (United States)

    Harmon, Tyler S; Crabtree, Michael D; Shammas, Sarah L; Posey, Ammon E; Clarke, Jane; Pappu, Rohit V

    2016-09-01

    Many intrinsically disordered proteins (IDPs) participate in coupled folding and binding reactions and form alpha helical structures in their bound complexes. Alanine, glycine, or proline scanning mutagenesis approaches are often used to dissect the contributions of intrinsic helicities to coupled folding and binding. These experiments can yield confounding results because the mutagenesis strategy changes the amino acid compositions of IDPs. Therefore, an important next step in mutagenesis-based approaches to mechanistic studies of coupled folding and binding is the design of sequences that satisfy three major constraints. These are (i) achieving a target intrinsic alpha helicity profile; (ii) fixing the positions of residues corresponding to the binding interface; and (iii) maintaining the native amino acid composition. Here, we report the development of a G: enetic A: lgorithm for D: esign of I: ntrinsic secondary S: tructure (GADIS) for designing sequences that satisfy the specified constraints. We describe the algorithm and present results to demonstrate the applicability of GADIS by designing sequence variants of the intrinsically disordered PUMA system that undergoes coupled folding and binding to Mcl-1. Our sequence designs span a range of intrinsic helicity profiles. The predicted variations in sequence-encoded mean helicities are tested against experimental measurements. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  14. Comparative Genome Structure, Secondary Metabolite, and Effector Coding Capacity across Cochliobolus Pathogens

    Energy Technology Data Exchange (ETDEWEB)

    Condon, Bradford J.; Leng, Yueqiang; Wu, Dongliang; Bushley, Kathryn E.; Ohm, Robin A.; Otillar, Robert; Martin, Joel; Schackwitz, Wendy; Grimwood, Jane; MohdZainudin, NurAinlzzati; Xue, Chunsheng; Wang, Rui; Manning, Viola A.; Dhillon, Braham; Tu, Zheng Jin; Steffenson, Brian J.; Salamov, Asaf; Sun, Hui; Lowry, Steve; LaButti, Kurt; Han, James; Copeland, Alex; Lindquist, Erika; Barry, Kerrie; Schmutz, Jeremy; Baker, Scott E.; Ciuffetti, Lynda M.; Grigoriev, Igor V.; Zhong, Shaobin; Turgeon, B. Gillian

    2013-01-24

    The genomes of five Cochliobolus heterostrophus strains, two Cochliobolus sativus strains, three additional Cochliobolus species (Cochliobolus victoriae, Cochliobolus carbonum, Cochliobolus miyabeanus), and closely related Setosphaeria turcica were sequenced at the Joint Genome Institute (JGI). The datasets were used to identify SNPs between strains and species, unique genomic regions, core secondary metabolism genes, and small secreted protein (SSP) candidate effector encoding genes with a view towards pinpointing structural elements and gene content associated with specificity of these closely related fungi to different cereal hosts. Whole-genome alignment shows that three to five of each genome differs between strains of the same species, while a quarter of each genome differs between species. On average, SNP counts among field isolates of the same C. heterostrophus species are more than 25 higher than those between inbred lines and 50 lower than SNPs between Cochliobolus species. The suites of nonribosomal peptide synthetase (NRPS), polyketide synthase (PKS), and SSP encoding genes are astoundingly diverse among species but remarkably conserved among isolates of the same species, whether inbred or field strains, except for defining examples that map to unique genomic regions. Functional analysis of several strain-unique PKSs and NRPSs reveal a strong correlation with a role in virulence.

  15. Fold classification based on secondary structure – how much is gained by including loop topology?

    Directory of Open Access Journals (Sweden)

    Przytycka Teresa

    2006-03-01

    Full Text Available Abstract Background It has been proposed that secondary structure information can be used to classify (to some extend protein folds. Since this method utilizes very limited information about the protein structure, it is not surprising that it has a higher error rate than the approaches that use full 3D fold description. On the other hand, the comparing of 3D protein structures is computing intensive. This raises the question to what extend the error rate can be decreased with each new source of information, especially if the new information can still be used with simple alignment algorithms. We consider the question whether the information about closed loops can improve the accuracy of this approach. While the answer appears to be obvious, we had to overcome two challenges. First, how to code and to compare topological information in such a way that local alignment of strings will properly identify similar structures. Second, how to properly measure the effect of new information in a large data sample. We investigate alternative ways of computing and presenting this information. Results We used the set of beta proteins with at most 30% pairwise identity to test the approach; local alignment scores were used to build a tree of clusters which was evaluated using a new log-odd cluster scoring function. In particular, we derive a closed formula for the probability of obtaining a given score by chance.Parameters of local alignment function were optimized using a genetic algorithm. Of 81 folds that had more than one representative in our data set, log-odds scores registered significantly better clustering in 27 cases and significantly worse in 6 cases, and small differences in the remaining cases. Various notions of the significant change or average change were considered and tried, and the results were all pointing in the same direction. Conclusion We found that, on average, properly presented information about the loop topology improves noticeably

  16. Phylogenetic relationships of Salmonella based on rRNA sequences

    DEFF Research Database (Denmark)

    Christensen, H.; Nordentoft, Steen; Olsen, J.E.

    1998-01-01

    separated by 16S rRNA analysis and found to be closely related to the Escherichia coli and Shigella complex by both 16S and 23S rRNA analyses. The diphasic serotypes S. enterica subspp. I and VI were separated from the monophasic serotypes subspp. IIIa and IV, including S. bongori, by 23S rRNA sequence...

  17. Projection Structure by Single-Particle Electron Microscopy of Secondary Transport Proteins GItT, Cits, and GltS

    NARCIS (Netherlands)

    Moscicka, Katarzyna B.; Krupnik, Tomasz; Boekema, Egbert J.; Lolkema, Juke S.; Mościcka, Katarzyna B.

    2009-01-01

    The structure of three secondary transporter proteins, GltT of Bacillus stearothermophilus, CitS of Klebsiella pneumoniae, and GltS of Escherichia coli, was studied. The proteins were purified to homogeneity ill detergent solution by Ni(2+)-NTA affinity chromatography, and the complexes were

  18. Effect of Programmed Instruction on Students' Attitude towards Structure of the Atom and the Periodic Table among Kenyan Secondary Schools

    Science.gov (United States)

    Wangila, M. J.; Martin, W.; Ronald, M.

    2015-01-01

    This study examined the effect of Programmed Instruction on students' attitude towards Structure of the Atom and the Periodic Table (SAPT) among mixed (co-educational) secondary schools of Butere district, Kakamega county, Kenya. The quasi-experimental research design was adopted, using the nonrandomized Solomon four-group as a model. The sample…

  19. Observed lesson structure during the first year of secondary education : Exploration of change and link with academic engagement

    NARCIS (Netherlands)

    Maulana, Ridwan; Opdenakker, Marie-Christine; Stroet, Kim; Bosker, Roel

    This study investigates whether lesson structure (LS) matters and which components are important for academic engagement during the first grade of secondary education. Data from videoed lessons of 10 Dutch and 12 Indonesian teachers analyzed using an observation protocol show that six LS components

  20. Making Sense of Abstract Algebra: Exploring Secondary Teachers' Understandings of Inverse Functions in Relation to Its Group Structure

    Science.gov (United States)

    Wasserman, Nicholas H.

    2017-01-01

    This article draws on semi-structured, task-based interviews to explore secondary teachers' (N = 7) understandings of inverse functions in relation to abstract algebra. In particular, a concept map task is used to understand the degree to which participants, having recently taken an abstract algebra course, situated inverse functions within its…

  1. Relationship between mRNA secondary structure and sequence variability in Chloroplast genes: possible life history implications

    Directory of Open Access Journals (Sweden)

    Seligmann Hervé

    2008-01-01

    Full Text Available Abstract Background Synonymous sites are freer to vary because of redundancy in genetic code. Messenger RNA secondary structure restricts this freedom, as revealed by previous findings in mitochondrial genes that mutations at third codon position nucleotides in helices are more selected against than those in loops. This motivated us to explore the constraints imposed by mRNA secondary structure on evolutionary variability at all codon positions in general, in chloroplast systems. Results We found that the evolutionary variability and intrinsic secondary structure stability of these sequences share an inverse relationship. Simulations of most likely single nucleotide evolution in Psilotum nudum and Nephroselmis olivacea mRNAs, indicate that helix-forming propensities of mutated mRNAs are greater than those of the natural mRNAs for short sequences and vice-versa for long sequences. Moreover, helix-forming propensity estimated by the percentage of total mRNA in helices increases gradually with mRNA length, saturating beyond 1000 nucleotides. Protection levels of functionally important sites vary across plants and proteins: r-strategists minimize mutation costs in large genes; K-strategists do the opposite. Conclusion Mrna length presumably predisposes shorter mRNAs to evolve under different constraints than longer mRNAs. The positive correlation between secondary structure protection and functional importance of sites suggests that some sites might be conserved due to packing-protection constraints at the nucleic acid level in addition to protein level constraints. Consequently, nucleic acid secondary structure a priori biases mutations. The converse (exposure of conserved sites apparently occurs in a smaller number of cases, indicating a different evolutionary adaptive strategy in these plants. The differences between the protection levels of functionally important sites for r- and K-strategists reflect their respective molecular adaptive

  2. Analysis of energy-based algorithms for RNA secondary structure prediction.

    Science.gov (United States)

    Hajiaghayi, Monir; Condon, Anne; Hoos, Holger H

    2012-02-01

    RNA molecules play critical roles in the cells of organisms, including roles in gene regulation, catalysis, and synthesis of proteins. Since RNA function depends in large part on its folded structures, much effort has been invested in developing accurate methods for prediction of RNA secondary structure from the base sequence. Minimum free energy (MFE) predictions are widely used, based on nearest neighbor thermodynamic parameters of Mathews, Turner et al. or those of Andronescu et al. Some recently proposed alternatives that leverage partition function calculations find the structure with maximum expected accuracy (MEA) or pseudo-expected accuracy (pseudo-MEA) methods. Advances in prediction methods are typically benchmarked using sensitivity, positive predictive value and their harmonic mean, namely F-measure, on datasets of known reference structures. Since such benchmarks document progress in improving accuracy of computational prediction methods, it is important to understand how measures of accuracy vary as a function of the reference datasets and whether advances in algorithms or thermodynamic parameters yield statistically significant improvements. Our work advances such understanding for the MFE and (pseudo-)MEA-based methods, with respect to the latest datasets and energy parameters. We present three main findings. First, using the bootstrap percentile method, we show that the average F-measure accuracy of the MFE and (pseudo-)MEA-based algorithms, as measured on our largest datasets with over 2000 RNAs from diverse families, is a reliable estimate (within a 2% range with high confidence) of the accuracy of a population of RNA molecules represented by this set. However, average accuracy on smaller classes of RNAs such as a class of 89 Group I introns used previously in benchmarking algorithm accuracy is not reliable enough to draw meaningful conclusions about the relative merits of the MFE and MEA-based algorithms. Second, on our large datasets, the

  3. Purification and the Secondary Structure of Fucoidanase from Fusarium sp. LD8

    Directory of Open Access Journals (Sweden)

    Wu Qianqian

    2011-01-01

    Full Text Available The fucoidanase from Fusarium sp. (LD8 was obtained by solid-state fermentation. The fermented solid medium was extracted by citric acid buffer, and the extracts were precipitated by acetone and purified by Sephadex G-100 successively. The results showed that the specific fucoidanase activity of purified enzyme was 22.7-fold than that of the crude enzyme. The recovery of the enzyme was 23.9%. The purified enzyme gave a single band on SDS-PAGE gel, and the molecular weight of fucoidanase was about 64 kDa. The isoelectric point of the enzyme was 4.5. The enzyme properties were also studied. The results showed that the optimum temperature and pH were 60°C and 6.0, respectively; the temperature of half inactivation was 50°C, and the most stable pH for the enzyme was 6.0. KM, and the Vmax  of the enzyme was 8.9 mg·L−1 and 2.02 mg·min−1·mL−1 by using fucoidan from Fucus vesiculosus as substrate. The compositions of the secondary structure of fucoidanase were estimated by FTIR, the second derivative spectra, and the curve-fitting analysis of the amide I bands in their spectra. The results showed that β-sheet was the dominant component (58.6% and α-helix was the least (12%; the content of β-turn and random coil were 15.39% and 14.5%, respectively.

  4. JABAWS 2.2 Distributed Web Services for Bioinformatics: Protein Disorder, Conservation and RNA Secondary Structure.

    Science.gov (United States)

    Troshin, Peter V; Procter, James B; Sherstnev, Alexander; Barton, Daniel L; Madeira, Fábio; Barton, Geoffrey J

    2018-01-30

    JABAWS 2.2 is a computational framework that simplifies the deployment of web services for Bioinformatics. In addition to the five multiple sequence alignment (MSA) algorithms in JABAWS 1.0, JABAWS 2.2 includes three additional MSA programs (Clustal Omega, MSAprobs, GLprobs), four protein disorder prediction methods (DisEMBL, IUPred, Ronn, GlobPlot), 18 measures of protein conservation as implemented in AACon, and RNA secondary structure prediction by the RNAalifold program. JABAWS 2.2 can be deployed on a variety of in-house or hosted systems. JABAWS 2.2 web services may be accessed from the Jalview multiple sequence analysis workbench (Version 2.8 and later), as well as directly via the JABAWS command line interface (CLI) client. JABAWS 2.2 can be deployed on a local virtual server as a Virtual Appliance (VA) or simply as a Web Application Archive (WAR) for private use. Improvements in JABAWS 2.2 also include simplified installation and a range of utility tools for usage statistics collection, and web services querying and monitoring. The JABAWS CLI client has been updated to support all the new services and allow integration of JABAWS 2.2 services into conventional scripts. A public JABAWS 2 server has been in production since December 2011 and served over 800,000 analyses for users worldwide. JABAWS 2.2 is made freely available under the Apache 2 license and can be obtained from: http://www.compbio.dundee.ac.uk/jabaws. g.j.barton@dundee.ac.uk.

  5. Defining scaffold geometries for interacting with proteins: geometrical classification of secondary structure linking regions

    Science.gov (United States)

    Tran, Tran T.; Kulis, Christina; Long, Steven M.; Bryant, Darryn; Adams, Peter; Smythe, Mark L.

    2010-11-01

    Medicinal chemists synthesize arrays of molecules by attaching functional groups to scaffolds. There is evidence suggesting that some scaffolds yield biologically active molecules more than others, these are termed privileged substructures. One role of the scaffold is to present its side-chains for molecular recognition, and biologically relevant scaffolds may present side-chains in biologically relevant geometries or shapes. Since drug discovery is primarily focused on the discovery of compounds that bind to proteinaceous targets, we have been deciphering the scaffold shapes that are used for binding proteins as they reflect biologically relevant shapes. To decipher the scaffold architecture that is important for binding protein surfaces, we have analyzed the scaffold architecture of protein loops, which are defined in this context as continuous four residue segments of a protein chain that are not part of an α-helix or β-strand secondary structure. Loops are an important molecular recognition motif of proteins. We have found that 39 clusters reflect the scaffold architecture of 89% of the 23,331 loops in the dataset, with average intra-cluster and inter-cluster RMSD of 0.47 and 1.91, respectively. These protein loop scaffolds all have distinct shapes. We have used these 39 clusters that reflect the scaffold architecture of protein loops as biological descriptors. This involved generation of a small dataset of scaffold-based peptidomimetics. We found that peptidomimetic scaffolds with reported biological activities matched loop scaffold geometries and those peptidomimetic scaffolds with no reported biologically activities did not. This preliminary evidence suggests that organic scaffolds with tight matches to the preferred loop scaffolds of proteins, implies the likelihood of the scaffold to be biologically relevant.

  6. Analysis of sequencing data for probing RNA secondary structures and protein-RNA binding in studying posttranscriptional regulations.

    Science.gov (United States)

    Hu, Xihao; Wu, Yang; Lu, Zhi John; Yip, Kevin Y

    2016-11-01

    High-throughput sequencing has been used to study posttranscriptional regulations, where the identification of protein-RNA binding is a major and fast-developing sub-area, which is in turn benefited by the sequencing methods for whole-transcriptome probing of RNA secondary structures. In the study of RNA secondary structures using high-throughput sequencing, bases are modified or cleaved according to their structural features, which alter the resulting composition of sequencing reads. In the study of protein-RNA binding, methods have been proposed to immuno-precipitate (IP) protein-bound RNA transcripts in vitro or in vivo By sequencing these transcripts, the protein-RNA interactions and the binding locations can be identified. For both types of data, read counts are affected by a combination of confounding factors, including expression levels of transcripts, sequence biases, mapping errors and the probing or IP efficiency of the experimental protocols. Careful processing of the sequencing data and proper extraction of important features are fundamentally important to a successful analysis. Here we review and compare different experimental methods for probing RNA secondary structures and binding sites of RNA-binding proteins (RBPs), and the computational methods proposed for analyzing the corresponding sequencing data. We suggest how these two types of data should be integrated to study the structural properties of RBP binding sites as a systematic way to better understand posttranscriptional regulations. © The Author 2015. Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

  7. Contrasting evolutionary patterns of 28S and ITS rRNA genes reveal high intragenomic variation in Cephalenchus (Nematoda): Implications for species delimitation.

    Science.gov (United States)

    Pereira, Tiago José; Baldwin, James Gordon

    2016-05-01

    Concerted evolution is often assumed to be the evolutionary force driving multi-family genes, including those from ribosomal DNA (rDNA) repeat, to complete homogenization within a species, although cases of non-concerted evolution have been also documented. In this study, sequence variation of 28S and ITS ribosomal RNA (rRNA) genes in the genus Cephalenchus is assessed at three different levels, intragenomic, intraspecific, and interspecific. The findings suggest that not all Cephalenchus species undergo concerted evolution. High levels of intraspecific polymorphism, mostly due to intragenomic variation, are found in Cephalenchus sp1 (BRA-01). Secondary structure analyses of both rRNA genes and across different species show a similar substitution pattern, including mostly compensatory (CBC) and semi-compensatory (SBC) base changes, thus suggesting the functionality of these rRNA copies despite the variation found in some species. This view is also supported by low sequence variation in the 5.8S gene in relation to the flanking ITS-1 and ITS-2 as well as by the existence of conserved motifs in the former gene. It is suggested that potential cross-fertilization in some Cephalenchus species, based on inspection of female reproductive system, might contribute to both intragenomic and intraspecific polymorphism of their rRNA genes. These results reinforce the potential implications of intragenomic and intraspecific genetic diversity on species delimitation, especially in biodiversity studies based solely on metagenetic approaches. Knowledge of sequence variation will be crucial for accurate species diversity estimation using molecular methods. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Prediction of beta-turns at over 80% accuracy based on an ensemble of predicted secondary structures and multiple alignments

    Directory of Open Access Journals (Sweden)

    Kurgan Lukasz

    2008-10-01

    Full Text Available Abstract Background β-turn is a secondary protein structure type that plays significant role in protein folding, stability, and molecular recognition. To date, several methods for prediction of β-turns from protein sequences were developed, but they are characterized by relatively poor prediction quality. The novelty of the proposed sequence-based β-turn predictor stems from the usage of a window based information extracted from four predicted three-state secondary structures, which together with a selected set of position specific scoring matrix (PSSM values serve as an input to the support vector machine (SVM predictor. Results We show that (1 all four predicted secondary structures are useful; (2 the most useful information extracted from the predicted secondary structure includes the structure of the predicted residue, secondary structure content in a window around the predicted residue, and features that indicate whether the predicted residue is inside a secondary structure segment; (3 the PSSM values of Asn, Asp, Gly, Ile, Leu, Met, Pro, and Val were among the top ranked features, which corroborates with recent studies. The Asn, Asp, Gly, and Pro indicate potential β-turns, while the remaining four amino acids are useful to predict non-β-turns. Empirical evaluation using three nonredundant datasets shows favorable Qtotal, Qpredicted and MCC values when compared with over a dozen of modern competing methods. Our method is the first to break the 80% Qtotal barrier and achieves Qtotal = 80.9%, MCC = 0.47, and Qpredicted higher by over 6% when compared with the second best method. We use feature selection to reduce the dimensionality of the feature vector used as the input for the proposed prediction method. The applied feature set is smaller by 86, 62 and 37% when compared with the second and two third-best (with respect to MCC competing methods, respectively. Conclusion Experiments show that the proposed method constitutes an

  9. Increased 5S rRNA oxidation in Alzheimer's disease.

    Science.gov (United States)

    Ding, Qunxing; Zhu, Haiyan; Zhang, Bing; Soriano, Augusto; Burns, Roxanne; Markesbery, William R

    2012-01-01

    It is widely accepted that oxidative stress is involved in neurodegenerative disorders such as Alzheimer's disease (AD). Ribosomal RNA (rRNA) is one of the most abundant molecules in most cells and is affected by oxidative stress in the human brain. Previous data have indicated that total rRNA levels were decreased in the brains of subjects with AD and mild cognitive impairment concomitant with an increase in rRNA oxidation. In addition, level of 5S rRNA, one of the essential components of the ribosome complex, was significantly lower in the inferior parietal lobule (IP) brain area of subjects with AD compared with control subjects. To further evaluate the alteration of 5S rRNA in neurodegenerative human brains, multiple brain regions from both AD and age-matched control subjects were used in this study, including IP, superior and middle temporal gyro, temporal pole, and cerebellum. Different molecular pools including 5S rRNA integrated into ribosome complexes, free 5S rRNA, cytoplasmic 5S rRNA, and nuclear 5S rRNA were studied. Free 5S rRNA levels were significantly decreased in the temporal pole region of AD subjects and the oxidation of ribosome-integrated and free 5S rRNA was significantly increased in multiple brain regions in AD subjects compared with controls. Moreover, a greater amount of oxidized 5S rRNA was detected in the cytoplasm and nucleus of AD subjects compared with controls. These results suggest that the increased oxidation of 5S rRNA, especially the oxidation of free 5S rRNA, may be involved in the neurodegeneration observed in AD.

  10. Crystal Structure of a Bacterial Topoisomerase IB in Complex with DNA Reveals a Secondary DNA Binding Site

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Asmita; Yakovleva, Lyudmila; Shuman, Stewart; Mondragón, Alfonso (NWU); (SKI)

    2010-10-22

    Type IB DNA topoisomerases (TopIB) are monomeric enzymes that relax supercoils by cleaving and resealing one strand of duplex DNA within a protein clamp that embraces a {approx}21 DNA segment. A longstanding conundrum concerns the capacity of TopIB enzymes to stabilize intramolecular duplex DNA crossovers and form protein-DNA synaptic filaments. Here we report a structure of Deinococcus radiodurans TopIB in complex with a 12 bp duplex DNA that demonstrates a secondary DNA binding site located on the surface of the C-terminal domain. It comprises a distinctive interface with one strand of the DNA duplex and is conserved in all TopIB enzymes. Modeling of a TopIB with both DNA sites suggests that the secondary site could account for DNA crossover binding, nucleation of DNA synapsis, and generation of a filamentous plectoneme. Mutations of the secondary site eliminate synaptic plectoneme formation without affecting DNA cleavage or supercoil relaxation.

  11. Effects of heating on the secondary structure of proteins in milk powders using mid-infrared spectroscopy.

    Science.gov (United States)

    Ye, M P; Zhou, R; Shi, Y R; Chen, H C; Du, Y

    2017-01-01

    Milk powder is an important source of protein for adults and children. Protein is very sensitive to heat, which may influence people's usage of nutrients in milk powder. In this study, we describe the temperature-induced secondary structure of protein in milk powders. In this study, whole milk powder containing 24% protein and infant formula containing 11% protein were heated from 25 to 100°C. Attenuated total reflectance (ATR) spectra in the mid-infrared range 400-4,000cm(-1) were used to evaluate the heat effect on the secondary structure of protein in these 2 milk powders. The spectral changes as a function of temperature were maintained by difference spectra, second-derivative spectra and Gauss curve-fitted spectra. The secondary structures of protein in the whole milk powder began to change at 70°C and in the infant formula at 50°C. The β-sheet and β-turn structures in the whole milk powder both decreased in the range of 70 to 85°C, whereas α-helix structures increased. The loss of β-sheet and β-turn may contribute to the formation of α-helix in the whole milk powder. In infant formula powder, the β-sheet structure showed a decrease and then increase, whereas the β-turn structure showed an increase and then decrease in the range of 50 to 75°C, and no change was found for α-helix structures. This implies that heating may induce the transformation from β-sheet to β-turn. Overall, whole milk powder had better temperature stability than infant formula powder, probably because of the lower content of lipid in the former than in the latter. These results help us understand the thermal stability of protein in milk powder. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  12. BCL::Fold - De Novo Prediction of Complex and Large Protein Topologies by Assembly of Secondary Structure Elements

    Science.gov (United States)

    Karakaş, Mert; Woetzel, Nils; Staritzbichler, Rene; Alexander, Nathan; Weiner, Brian E.; Meiler, Jens

    2012-01-01

    Computational de novo protein structure prediction is limited to small proteins of simple topology. The present work explores an approach to extend beyond the current limitations through assembling protein topologies from idealized α-helices and β-strands. The algorithm performs a Monte Carlo Metropolis simulated annealing folding simulation. It optimizes a knowledge-based potential that analyzes radius of gyration, β-strand pairing, secondary structure element (SSE) packing, amino acid pair distance, amino acid environment, contact order, secondary structure prediction agreement and loop closure. Discontinuation of the protein chain favors sampling of non-local contacts and thereby creation of complex protein topologies. The folding simulation is accelerated through exclusion of flexible loop regions further reducing the size of the conformational search space. The algorithm is benchmarked on 66 proteins with lengths between 83 and 293 amino acids. For 61 out of these proteins, the best SSE-only models obtained have an RMSD100 below 8.0 Å and recover more than 20% of the native contacts. The algorithm assembles protein topologies with up to 215 residues and a relative contact order of 0.46. The method is tailored to be used in conjunction with low-resolution or sparse experimental data sets which often provide restraints for regions of defined secondary structure. PMID:23173050

  13. FTIR investigation of the effects of ultra-strong static magnetic field on the secondary structures of protein in bacteria

    Science.gov (United States)

    She, Zichao; Hu, Xing; Zhao, Xusheng; Ren, Zhongming; Ding, Guoji

    2009-07-01

    Secondary structures of protein in Escherichia coli ( E. coli) and Staphylococcus aureus ( S. aureus) exposed to the ultra-strong static magnetic field (SMF) were investigated by Fourier transformation infrared spectroscopy (FTIR). Difference index D value of amide I (1600-1700 cm -1) showed that the ultra-strong magnetic field had little impact on S. aureus, but had strong impact on E. coli. The results indicated that 3.46-9.92% of the disorder coils in the secondary structures of protein in E. coli were turned into α-helices under SMF while applying deconvolution and curve fitting to amide I. At the same time, intermolecular β-sheets transforming into intramolecular ones suggested that cohesion among protein molecules had been destroyed and intramolecular hydrogen bonds strengthened. All the differences among the compositions of protein's secondary structures in E. coli were mostly due to the varying degrees of various proteins affected by the magnetic field. The results may provide new insights into the structural changes of proteins induced by the SMF.

  14. Porter, PaleAle 4.0: high-accuracy prediction of protein secondary structure and relative solvent accessibility.

    Science.gov (United States)

    Mirabello, Claudio; Pollastri, Gianluca

    2013-08-15

    Protein secondary structure and solvent accessibility predictions are a fundamental intermediate step towards protein structure and function prediction. We present new systems for the ab initio prediction of protein secondary structure and solvent accessibility, Porter 4.0 and PaleAle 4.0. Porter 4.0 predicts secondary structure correctly for 82.2% of residues. PaleAle 4.0's accuracy is 80.0% for prediction in two classes with a 25% accessibility threshold. We show that the increasing training set sizes that come with the continuing growth of the Protein Data Bank keep yielding prediction quality improvements and examine the impact of protein resolution on prediction performances. Porter 4.0 and PaleAle 4.0 are freely available for academic users at http://distillf.ucd.ie/porterpaleale/. Up to 64 kb of input in FASTA format can be processed in a single submission, with predictions now being returned to the user within a single web page and, optionally, a single email.

  15. Identification of protein secondary structures by laser induced autofluorescence: A study of urea and GnHCl induced protein denaturation

    Science.gov (United States)

    Siddaramaiah, Manjunath; Satyamoorthy, Kapaettu; Rao, Bola Sadashiva Satish; Roy, Suparna; Chandra, Subhash; Mahato, Krishna Kishore

    2017-03-01

    In the present study an attempt has been made to interrogate the bulk secondary structures of some selected proteins (BSA, HSA, lysozyme, trypsin and ribonuclease A) under urea and GnHCl denaturation using laser induced autofluorescence. The proteins were treated with different concentrations of urea (3 M, 6 M, 9 M) and GnHCl (2 M, 4 M, 6 M) and the corresponding steady state autofluorescence spectra were recorded at 281 nm pulsed laser excitations. The recorded fluorescence spectra of proteins were then interpreted based on the existing PDB structures of the proteins and the Trp solvent accessibility (calculated using "Scratch protein predictor" at 30% threshold). Further, the influence of rigidity and conformation of the indole ring (caused by protein secondary structures) on the intrinsic fluorescence properties of proteins were also evaluated using fluorescence of ANS-HSA complexes, CD spectroscopy as well as with trypsin digestion experiments. The outcomes obtained clearly demonstrated GnHCl preferably disrupt helix as compared to the beta β-sheets whereas, urea found was more effective in disrupting β-sheets as compared to the helices. The other way round the proteins which have shown detectable change in the intrinsic fluorescence at lower concentrations of GnHCl were rich in helices whereas, the proteins which showed detectable change in the intrinsic fluorescence at lower concentrations of urea were rich in β-sheets. Since high salt concentrations like GnHCl and urea interfere in the secondary structure analysis by circular dichroism Spectrometry, the present method of analyzing secondary structures using laser induced autofluorescence will be highly advantageous over existing tools for the same.

  16. Monitoring of Batch Industrial Crystallization with Growth, Nucleation, and Agglomeration. Part 2: Structure Design for State Estimation with Secondary Measurements.

    Science.gov (United States)

    Porru, Marcella; Özkan, Leyla

    2017-08-30

    This work investigates the design of alternative monitoring tools based on state estimators for industrial crystallization systems with nucleation, growth, and agglomeration kinetics. The estimation problem is regarded as a structure design problem where the estimation model and the set of innovated states have to be chosen; the estimator is driven by the available measurements of secondary variables. On the basis of Robust Exponential estimability arguments, it is found that the concentration is distinguishable with temperature and solid fraction measurements while the crystal size distribution (CSD) is not. Accordingly, a state estimator structure is selected such that (i) the concentration (and other distinguishable states) are innovated by means of the secondary measurements processed with the geometric estimator (GE), and (ii) the CSD is estimated by means of a rigorous model in open loop mode. The proposed estimator has been tested through simulations showing good performance in the case of mismatch in the initial conditions, parametric plant-model mismatch, and noisy measurements.

  17. Active Transcription of rRNA Operons Condenses the Nucleoid in Escherichia coli: Examining the Effect of Transcription on Nucleoid Structure in the Absence of Transertion | Center for Cancer Research

    Science.gov (United States)

    In Escherichia coli the genome must be compacted ∼1,000-fold to be contained in a cellular structure termed the nucleoid. It is proposed that the structure of the nucleoid is determined by a balance of multiple compaction forces and one major expansion force. The latter is mediated by transertion, a coupling of transcription, translation, and translocation of nascent membrane proteins and/or exported proteins.

  18. A comparison of the crystal structures of eukaryotic and bacterial SSU ribosomal RNAs reveals common structural features in the hypervariable regions.

    Directory of Open Access Journals (Sweden)

    Jung C Lee

    Full Text Available While the majority of the ribosomal RNA structure is conserved in the three major domains of life--archaea, bacteria, and eukaryotes, specific regions of the rRNA structure are unique to at least one of these three primary forms of life. In particular, the comparative secondary structure for the eukaryotic SSU rRNA contains several regions that are different from the analogous regions in the bacteria. Our detailed analysis of two recently determined eukaryotic 40S ribosomal crystal structures, Tetrahymena thermophila and Saccharomyces cerevisiae, and the comparison of these results with the bacterial Thermus thermophilus 30S ribosomal crystal structure: (1 revealed that the vast majority of the comparative structure model for the eukaryotic SSU rRNA is substantiated, including the secondary structure that is similar to both bacteria and archaea as well as specific for the eukaryotes, (2 resolved the secondary structure for regions of the eukaryotic SSU rRNA that were not determined with comparative methods, (3 identified eukaryotic helices that are equivalent to the bacterial helices in several of the hypervariable regions, (4 revealed that, while the coaxially stacked compound helix in the 540 region in the central domain maintains the constant length of 10 base pairs, its two constituent helices contain 5+5 bp rather than the 6+4 bp predicted with comparative analysis of archaeal and eukaryotic SSU rRNAs.

  19. A novel method of protein secondary structure prediction with high segment overlap measure: support vector machine approach.

    Science.gov (United States)

    Hua, S; Sun, Z

    2001-04-27

    We have introduced a new method of protein secondary structure prediction which is based on the theory of support vector machine (SVM). SVM represents a new approach to supervised pattern classification which has been successfully applied to a wide range of pattern recognition problems, including object recognition, speaker identification, gene function prediction with microarray expression profile, etc. In these cases, the performance of SVM either matches or is significantly better than that of traditional machine learning approaches, including neural networks.The first use of the SVM approach to predict protein secondary structure is described here. Unlike the previous studies, we first constructed several binary classifiers, then assembled a tertiary classifier for three secondary structure states (helix, sheet and coil) based on these binary classifiers. The SVM method achieved a good performance of segment overlap accuracy SOV=76.2 % through sevenfold cross validation on a database of 513 non-homologous protein chains with multiple sequence alignments, which out-performs existing methods. Meanwhile three-state overall per-residue accuracy Q(3) achieved 73.5 %, which is at least comparable to existing single prediction methods. Furthermore a useful "reliability index" for the predictions was developed. In addition, SVM has many attractive features, including effective avoidance of overfitting, the ability to handle large feature spaces, information condensing of the given data set, etc. The SVM method is conveniently applied to many other pattern classification tasks in biology. Copyright 2001 Academic Press.

  20. [Secondary structure changes of insulin induced by PEF exposure at different temperatures using Raman spectra and theoretical model analysis].

    Science.gov (United States)

    Pei, Jian; Xie, Tao-Rong; Yan, Zhe; Chen, Shu-De; Qiao, Deng Jiang

    2011-06-01

    Recently, biological effects induced by weak electromagnetic fields have been a public concern. Our previous study found temperature and electromagnetic field co-effects on insulin conformation. Therefore, in the present study, Raman spectroscopy was employed to investigate the secondary structure changes of insulin molecule induced by pulsed electric field (PEF) exposure at various temperatures. The content changes in alpha helix of insulin were obtained. Then, protein helix-random coil transition model was used to quantitatively study the experimental results. The theoretical model could figure out the effect of PEF on alpha helix contents of insulin at different temperatures. The protein secondary structure transits from helix to random coil evoked by PEF exposure and change of thermodynamic environment, which could explain the reason for the decline of alpha helix content of insulin caused by PEF exposure together with temperature rising. The results offer experimental basis and theoretical reference for further study of the mechanism of nonthermal effects of weak electromagnetic fields on biological molecule secondary structure.

  1. The role of local secondary structure in the function of the trans-splicing motif of Brugia malayi.

    Science.gov (United States)

    Liu, Canhui; Chauhan, Chitra; Unnasch, Thomas R

    2010-02-01

    A 7-nt motif (the trans-splicing motif or TSM) was previously shown to be necessary and sufficient to direct trans-splicing of transgenic mRNAs in transgenic Brugia malayi embryos. Insertion of the TSM into two genes lacking a TSM homologue resulted in trans-splicing of transgenic mRNAs from one transgene but not the other, suggesting that local sequence context might affect TSM function. To test this hypothesis, constructs inserting the TSM into different positions of two B. malayi genes were tested for their ability to support trans-splicing of transgenic mRNAs. Transgenic mRNAs derived from constructs in which the insertion of the TSM did not result in a perturbation of the local predicted secondary structure were trans-spliced, while those in which the TSM perturbed the local secondary structure were not. These data suggest that local secondary structure plays a role in the ability of the TSM to direct trans-splicing.

  2. The role of local secondary structure in the function of the trans splicing motif of Brugia malayi

    Science.gov (United States)

    Liu, Canhui; Chauhan, Chitra; Unnasch, Thomas R.

    2009-01-01

    A 7nt motif (the trans-splicing motif or TSM) was previously shown to be necessary and sufficient to direct trans-splicing of transgenic mRNAs in transgenic B. malayi embryos. Insertion of the TSM into two genes lacking a TSM homologue resulted in-trans splicing of transgenic mRNAs from one transgene but not the other, suggesting that local sequence context might affect TSM function. To test this hypothesis, constructs inserting the TSM into different positions of two B. malayi genes were tested for their ability to support trans-splicing of transgenic mRNAs. Transgenic mRNAs derived from constructs in which the insertion of the TSM did not result in a perturbation of the local predicted secondary structure were trans-spliced, while those in which the TSM perturbed the local secondary structure were not. These data suggest that local secondary structure plays a role in the ability of the TSM to direct trans-splicing. PMID:19852985

  3. Developments in the Curriculum and Structures of Upper-Secondary Education in Australia: The Last Decade.

    Science.gov (United States)

    McKinnon, Ken

    1988-01-01

    Examines the recent influences on and development of upper-secondary Australian education. These influences include youth unemployment, rapid technological and social change, immigration, increasing federal role, and limited entry to tertiary education. Changes include broader curriculum planning to include all students, and improvement of the…

  4. [Characteristics of soil macrofaunal community structure in secondary forest and forest plantations in western Qinling Mountains of Northwest China].

    Science.gov (United States)

    Liu, Ji-Liang; Cao, Jing; Li, Shi-Jie; Pan, Chun-Lin; Pan, Cheng-Chen

    2012-09-01

    Long-term disturbance of human beings on secondary forest ecosystem would have profound impacts on belowground ecological processes, whereas the community structure and functional diversity of soil fauna would be sensitive to the changes of belowground ecological processes, with significance as an indicator of the changes. In this study, the method of hand-sorting was adopted to investigate the density of soil macrofaunal community in a secondary forest and the Pinus tabulaeformis, Larix kaempferi, Picea abie, and Picea asperata plantations of nearly 30 years old in Xiaolongshan forest area of western Qinling Mountains, and the PCA ordination and one-way ANOVA analysis were applied to analyze the community structure and trophic group composition of soil macrofauna in the five forest types. In the P. tabulaeformis and L. kaempferi plantations, the density of soil macrofaunal community was 3.0 and 2.1 times of that in the secondary forest, respectively, and the consumers/decomposers ratio of the community was obviously higher than that in the secondary forest. Among the plantations, P. tabulaeformis and L. kaempferi plantations had a significantly higher consumers/decomposers ratio of soil macrofaunal community than P. abies and P. asperata plantations. There was an obvious difference in community structure of soil macrofauna among the four plantations. The density of soil macrofaunal community in P. tabulaeformis and L. kaempferi plantations was 3.5 and 2.1 times higher than that in P. asperata plantation, respectively, whereas the group richness of soil macrofaunal community in P. tabulaeformis plantation was 1.5 times of that in P. abies and P. asperata plantations.

  5. Framework for Structural Online Health Monitoring of Aging and Degradation of Secondary Systems due to some Aspects of Erosion

    Energy Technology Data Exchange (ETDEWEB)

    Gribok, Andrei [Idaho National Lab. (INL), Idaho Falls, ID (United States); Patnaik, Sobhan [Idaho National Lab. (INL), Idaho Falls, ID (United States); Williams, Christian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Pattanaik, Marut [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kanakala, Raghunath [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-09-01

    This report describes the current state of research related to critical aspects of erosion and selected aspects of degradation of secondary components in nuclear power plants. The report also proposes a framework for online health monitoring of aging and degradation of secondary components. The framework consists of an integrated multi-sensor modality system which can be used to monitor different piping configurations under different degradation conditions. The report analyses the currently known degradation mechanisms and available predictive models. Based on this analysis, the structural health monitoring framework is proposed. The Light Water Reactor Sustainability Program began to evaluate technologies that could be used to perform online monitoring of piping and other secondary system structural components in commercial NPPs. These online monitoring systems have the potential to identify when a more detailed inspection is needed using real-time measurements, rather than at a pre-determined inspection interval. This transition to condition-based, risk informed automated maintenance will contribute to a significant reduction of operations and maintenance costs that account for the majority of nuclear power generation costs. There is unanimous agreement between industry experts and academic researchers that identifying and prioritizing inspection locations in secondary piping systems (for example, in raw water piping or diesel piping) would eliminate many excessive in-service inspections. The proposed structural health monitoring framework takes aim at answering this challenge by combining long-range guided wave technologies with other monitoring techniques, which can significantly increase the inspection length and pinpoint the locations that degraded the most. More widely, the report suggests research efforts aimed at developing, validating, and deploying online corrosion monitoring techniques for complex geometries, which are pervasive in NPPs.

  6. Implementation of a structured guideline-based program for the secondary prevention of ischemic stroke in China.

    Science.gov (United States)

    Peng, Bin; Ni, Jun; Anderson, Craig S; Zhu, Yicheng; Wang, Yongjun; Pu, Chuanqiang; Wu, Jiang; Wang, Jianming; Zhou, Lixin; Yao, Ming; He, Jia; Shan, Guangliang; Gao, Shan; Xu, Weihai; Cui, Liying

    2014-02-01

    High rates of ischemic stroke and poor adherence to secondary prevention measures are observed in the Chinese population. We used a national, multicenter, cluster-randomized controlled trial in which 47 hospitals were randomized to either a structured care program group (n=23) or a usual care group (n=24). The structured care program consisted of a specialist-administered, guideline-recommended pharmaceutical treatment and a lifestyle modification algorithm associated with written and Internet-accessed educational material for patients for the secondary prevention of ischemic stroke. The primary efficacy outcome was the proportion of patients who adhered to the recommended measures at 12-month postdischarge. This trial is registered with ClinicalTrial.gov (NCT00664846). At 12 months, 1287 (72.1%) patients in the Standard Medical Management in Secondary Prevention of Ischemic Stroke in China (SMART) group and 1430 (72%) patients in the usual care group had completed the 12-month follow-up (P=0.342). Compared with the usual care group, those in the SMART group showed higher adherence to statins (56% versus 33%; P=0.006) but no difference in adherence to antiplatelet (81% versus 75%; P=0.088), antihypertensive (67% versus 69%; P=0.661), or diabetes mellitus drugs (73% versus 67%; P=0.297). No significant difference in the composite end point (new-onset ischemic stroke, hemorrhagic stroke, acute coronary syndrome, and all-cause death) was observed (3.56% versus 3.59%; P=0.921). The implementation of a program to improve adherence to secondary ischemic stroke prevention efforts in China is feasible, but these programs had only a limited impact on adherence and no impact on 1-year outcomes. Further development of a structured program to reduce vascular events after stroke is needed. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT00664846.

  7. Floristic and structural characterization of three secondary forest fragments in Costa Rica

    OpenAIRE

    Morales, Carlos O

    2015-01-01

    Observations on successional development and floristic composition were made in 25 plots (10x2 m) established in three contiguous secondary forest fragments of the Lankester Botanical Garden, Costa Rica. Human activities favored forest regeneration there by 1) protecting an abandoned farm and pasture area since 1970, and 2) planting and propagating plant species. Planting successfully growing native and introduced species can accelerate the succession process, avoid dominance of pioneer or in...

  8. Secondary Interactions Involving Zinc-Bound Ligands: Roles in Structural Stabilization and Macromolecular Interactions

    OpenAIRE

    Namuswe, Frances; Berg, Jeremy M.

    2011-01-01

    A large number of proteins contain bound zinc ions. These zinc ions are frequently coordinated by a combination of histidine and cysteine residues. In addition to atoms that coordinate directly to the zinc ions, these side chains have groups that can donate or accept hydrogen bonds from other groups. These secondary interactions can help stabilize the zinc-binding sites, can contribute to protein folding and stability, and, on occasion, can participate in interactions with other macromolecule...

  9. Secondary Plant Products Causing Photosensitization in Grazing Herbivores: Their Structure, Activity and Regulation

    Directory of Open Access Journals (Sweden)

    Jane C. Quinn

    2014-01-01

    Full Text Available Photosensitivity in animals is defined as a severe dermatitis that results from a heightened reactivity of skin cells and associated dermal tissues upon their exposure to sunlight, following ingestion or contact with UV reactive secondary plant products. Photosensitivity occurs in animal cells as a reaction that is mediated by a light absorbing molecule, specifically in this case a plant-produced metabolite that is heterocyclic or polyphenolic. In sensitive animals, this reaction is most severe in non-pigmented skin which has the least protection from UV or visible light exposure. Photosensitization in a biological system such as the epidermis is an oxidative or other chemical change in a molecule in response to light-induced excitation of endogenous or exogenously-delivered molecules within the tissue. Photo-oxidation can also occur in the plant itself, resulting in the generation of reactive oxygen species, free radical damage and eventual DNA degradation. Similar cellular changes occur in affected herbivores and are associated with an accumulation of photodynamic molecules in the affected dermal tissues or circulatory system of the herbivore. Recent advances in our ability to identify and detect secondary products at trace levels in the plant and surrounding environment, or in organisms that ingest plants, have provided additional evidence for the role of secondary metabolites in photosensitization of grazing herbivores. This review outlines the role of unique secondary products produced by higher plants in the animal photosensitization process, describes their chemistry and localization in the plant as well as impacts of the environment upon their production, discusses their direct and indirect effects on associated animal systems and presents several examples of well-characterized plant photosensitization in animal systems.

  10. Molecular systematics of Barbatosphaeria (Sordariomycetes): multigene phylogeny and secondary ITS structure

    OpenAIRE

    Réblová, M.; Réblová, K.; Štěpánek, V.

    2015-01-01

    Thirteen morphologically similar strains of barbatosphaeria- and tectonidula-like fungi were studied based on the comparison of cultural and morphological features of sexual and asexual morphs and phylogenetic analyses of five nuclear loci, i.e. internal transcribed spacer rDNA operon (ITS), large and small subunit nuclear ribosomal DNA, ?-tubulin, and second largest subunit of RNA polymerase II. Phylogenetic results were supported by in-depth comparative analyses of common core secondary str...

  11. Common 5S rRNA variants are likely to be accepted in many sequence contexts

    Science.gov (United States)

    Zhang, Zhengdong; D'Souza, Lisa M.; Lee, Youn-Hyung; Fox, George E.

    2003-01-01

    Over evolutionary time RNA sequences which are successfully fixed in a population are selected from among those that satisfy the structural and chemical requirements imposed by the function of the RNA. These sequences together comprise the structure space of the RNA. In principle, a comprehensive understanding of RNA structure and function would make it possible to enumerate which specific RNA sequences belong to a particular structure space and which do not. We are using bacterial 5S rRNA as a model system to attempt to identify principles that can be used to predict which sequences do or do not belong to the 5S rRNA structure space. One promising idea is the very intuitive notion that frequently seen sequence changes in an aligned data set of naturally occurring 5S rRNAs would be widely accepted in many other 5S rRNA sequence contexts. To test this hypothesis, we first developed well-defined operational definitions for a Vibrio region of the 5S rRNA structure space and what is meant by a highly variable position. Fourteen sequence variants (10 point changes and 4 base-pair changes) were identified in this way, which, by the hypothesis, would be expected to incorporate successfully in any of the known sequences in the Vibrio region. All 14 of these changes were constructed and separately introduced into the Vibrio proteolyticus 5S rRNA sequence where they are not normally found. Each variant was evaluated for its ability to function as a valid 5S rRNA in an E. coli cellular context. It was found that 93% (13/14) of the variants tested are likely valid 5S rRNAs in this context. In addition, seven variants were constructed that, although present in the Vibrio region, did not meet the stringent criteria for a highly variable position. In this case, 86% (6/7) are likely valid. As a control we also examined seven variants that are seldom or never seen in the Vibrio region of 5S rRNA sequence space. In this case only two of seven were found to be potentially valid. The

  12. Intrusive growth of primary and secondary phloem fibres in hemp stem determines fibre-bundle formation and structure.

    Science.gov (United States)

    Snegireva, Anastasia; Chernova, Tatyana; Ageeva, Marina; Lev-Yadun, Simcha; Gorshkova, Tatyana

    2015-05-27

    Plant fibres-cells with important mechanical functions and a widely used raw material-are usually identified in microscopic sections only after reaching a significant length or after developing a thickened cell wall. We characterized the early developmental stages of hemp (Cannabis sativa) stem phloem fibres, both primary (originating from the procambium) and secondary (originating in the cambium), when they still had only a primary cell wall. We gave a major emphasis to the role of intrusive elongation, the specific type of plant cell growth by which fibres commonly attain large cell length. We could identify primary phloem fibres at a distance of only 1.2-1.5 mm from the shoot apical meristem when they grew symplastically with the surrounding tissues. Half a millimeter further downwards along the stem, fibres began their intrusive elongation, which led to a sharp increase in fibre numbers visible within the stem cross-sections. The intrusive elongation of primary phloem fibres was completed within the several distal centimetres of the growing stem, before the onset of their secondary cell wall formation. The formation of secondary phloem fibres started long after the beginning of secondary xylem formation. Our data indicate that only a small portion of the fusiform cambial initials (fibres. The key determinant of final bundle structure, both for primary and secondary phloem fibres, is intrusive growth. Through bi-directional elongation, fibres join other fibres initiated individually in other stem levels, thus forming the bundles. Our results provide the specific developmental basis for further biochemical and molecular-genetic studies of phloem fibre development in hemp, but may be applied to many other species. Published by Oxford University Press on behalf of the Annals of Botany Company.

  13. Effects of Cylindrical Charge Geometry and Secondary Combustion Reactions on the Internal Blast Loading of Reinforced Concrete Structures

    Energy Technology Data Exchange (ETDEWEB)

    Price, Matthew A. [New Mexico Inst. of Mining and Technology, Socorro, NM (United States)

    2005-05-01

    An understanding of the detonation phenomenon and airblast behavior for cylindrical high-explosive charges is essential in developing predictive capabilities for tests and scenarios involving these charge geometries. Internal tests on reinforced concrete structures allowed for the analysis of cylindrical charges and the effect of secondary reactions occurring in confined structures. The pressure profiles that occur close to a cylindrical explosive charge are strongly dependent on the length-to-diameter ratio (L/D) of the charge. This study presents a comparison of finite-element code models (i.e., AUTODYN) to empirical methods for predicting airblast behavior from cylindrical charges. Current finite element analysis (FEA) and blast prediction codes fail to account for the effects of secondary reactions (fireballs) that occur with underoxidized explosives. Theoretical models were developed for TNT and validated against literature. These models were then applied to PBX 9501 for predictions of the spherical fireball diameter and time duration. The following relationships for PBX 9501 were derived from this analysis (units of ft, lb, s). Comparison of centrally located equivalent weight charges using cylindrical and spherical geometries showed that the average impulse on the interior of the structure is ~3%–5% higher for the spherical charge. Circular regions of high impulse that occur along the axial direction of the cylindrical charge must be considered when analyzing structural response.

  14. [Isolation, identification and structural characterization of secondary metabolites from amarine sponge-derived rare actinobacterium Dermacoccus sp. X4].

    Science.gov (United States)

    Zhang, Yanfeng; Xu, Yong; Chen, Lei; Hu, Jun; Zhang, Xuecheng; Fang, Wei; Fang, Zemin; Xiao, Yazhong

    2016-05-25

    We isolated and identified the symbiotic and adnascent microorganisms from an unidentified sponge collected from 10-meter-deep seawater of the Paracel Islands in China. A total of 16 strains were obtained and identified. Through bacteriostatic activity assay, one of the strains, Dermacoccus sp. X4, was found to effectively inhibit the growth of Staphylococcus aureus. Subsequently, its secondary metabolites were purified by silica gel partition, octadecylsilane (ODS) reverse phase, Sephadex™LH-20 size exclusion, and C18 reverse phase chromatography. Using liquid chromatography, mass spectrometry, and nuclear magnetic resonance, three of the purified compounds were structurally characterized to be one 3-(4-hydroxybenzyl) hexahydropyrrolo [1,2-a]pyrazine-1,4-dione and two indole acid glycerides. This is the first report about indole acid glyceride isolated from microbial secondary metabolites, enriching marine drug candidate resources.

  15. Effects of Very Low Dose Fast Neutrons on Cell Membrane And Secondary Protein Structure in Rat Erythrocytes.

    Science.gov (United States)

    Saeed, A; Raouf, Gehan A; Nafee, Sherif S; Shaheen, Salem A; Al-Hadeethi, Y

    2015-01-01

    The effects of ionizing radiation on biological cells have been reported in several literatures. Most of them were mainly concerned with doses greater than 0.01 Gy and were also concerned with gamma rays. On the other hand, the studies on very low dose fast neutrons (VLDFN) are rare. In this study, we have investigated the effects of VLDFN on cell membrane and protein secondary structure of rat erythrocytes. Twelve female Wistar rats were irradiated with neutrons of total dose 0.009 Gy (241Am-Be, 0.2 mGy/h) and twelve others were used as control. Blood samples were taken at the 0, 4th, 8th, and 12th days postirradiation. Fourier transform infrared (FTIR) spectra of rat erythrocytes were recorded. Second derivative and curve fitting were used to analysis FTIR spectra. Hierarchical cluster analysis (HCA) was used to classify group spectra. The second derivative and curve fitting of FTIR spectra revealed that the most significant alterations in the cell membrane and protein secondary structure upon neutron irradiation were detected after 4 days postirradiation. The increase in membrane polarity, phospholipids chain length, packing, and unsaturation were noticed from the corresponding measured FTIR area ratios. This may be due to the membrane lipid peroxidation. The observed band shift in the CH2 stretching bands toward the lower frequencies may be associated with the decrease in membrane fluidity. The curve fitting of the amide I revealed an increase in the percentage area of α-helix opposing a decrease in the β-structure protein secondary structure, which may be attributed to protein denaturation. The results provide detailed insights into the VLDFN effects on erythrocytes. VLDFN can cause an oxidative stress to the irradiated erythrocytes, which appears clearly after 4 days postirradiation.

  16. Implications of secondary structure prediction and amino acid sequence comparison of class I and class II phosphoribosyl diphosphate synthases on catalysis, regulation, and quaternary structure

    DEFF Research Database (Denmark)

    Krath, B N; Hove-Jensen, B

    2001-01-01

    is consistent with a homotrimer. Secondary structure prediction shows that spinach PRPP synthase isozyme 4 has a general folding similar to that of Bacillus subtilis class I PRPP synthase, for which the three-dimensional structure has been solved, as the position and extent of helices and beta-sheets of the two......Spinach 5-phospho-D-ribosyl alpha-1-diphosphate (PRPP) synthase isozyme 4 was synthesized in Escherichia coli and purified to near homogeneity. The activity of the enzyme is independent of P(i); it is inhibited by ADP in a competitive manner, indicating a lack of an allosteric site; and it accepts...

  17. StructMiner: a tool for alignment and detection of conserved secondary structure.

    Science.gov (United States)

    Yang, Qian; Blanchette, Mathieu

    2004-01-01

    Functional RNA molecules typically have structural patterns that are highly conserved in evolution. Here we present an algorithmic method for multiple alignment of RNAs, taking into consideration both structural similarity and sequence identity. Furthermore, our window-sized comparative analysis corrects the misaligned structure within a distance threshold and identifies the conserved substructures. Based on this new algorithm, StructMiner outperforms existing approaches, which ignore structure information for the alignment and lack the effective means to adjust the misalignments in the analysis phase. In addition, StructMiner is efficient in terms of CPU time and memory usage, making it suitable for structural analysis of very long sequences.

  18. Curriculum Reform and Supporting Structures at Schools: Challenges for Life Skills Planning for Secondary School Students in China (with Particular Reference to Hong Kong)

    Science.gov (United States)

    Lee, John Chi-Kin

    2017-01-01

    Demand has risen for the introduction of career education in senior secondary schooling to enhance students' transition from study to work. Against such a background, this paper aims to discuss the curriculum reforms and supporting structures in schools and to explore the challenges of life skills planning for secondary school students in China…

  19. Clustering of 3D-Structure Similarity Based Network of Secondary Metabolites Reveals Their Relationships with Biological Activities.

    Science.gov (United States)

    Ohtana, Yuki; Abdullah, Azian Azamimi; Altaf-Ul-Amin, Md; Huang, Ming; Ono, Naoaki; Sato, Tetsuo; Sugiura, Tadao; Horai, Hisayuki; Nakamura, Yukiko; Morita Hirai, Aki; Lange, Klaus W; Kibinge, Nelson K; Katsuragi, Tetsuo; Shirai, Tsuyoshi; Kanaya, Shigehiko

    2014-12-01

    Developing database systems connecting diverse species based on omics is the most important theme in big data biology. To attain this purpose, we have developed KNApSAcK Family Databases, which are utilized in a number of researches in metabolomics. In the present study, we have developed a network-based approach to analyze relationships between 3D structure and biological activity of metabolites consisting of four steps as follows: construction of a network of metabolites based on structural similarity (Step 1), classification of metabolites into structure groups (Step 2), assessment of statistically significant relations between structure groups and biological activities (Step 3), and 2-dimensional clustering of the constructed data matrix based on statistically significant relations between structure groups and biological activities (Step 4). Applying this method to a data set consisting of 2072 secondary metabolites and 140 biological activities reported in KNApSAcK Metabolite Activity DB, we obtained 983 statistically significant structure group-biological activity pairs. As a whole, we systematically analyzed the relationship between 3D-chemical structures of metabolites and biological activities. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Exploring microbial diversity and taxonomy using SSU rRNA hypervariable tag sequencing.

    Directory of Open Access Journals (Sweden)

    Susan M Huse

    2008-11-01

    Full Text Available Massively parallel pyrosequencing of hypervariable regions from small subunit ribosomal RNA (SSU rRNA genes can sample a microbial community two or three orders of magnitude more deeply per dollar and per hour than capillary sequencing of full-length SSU rRNA. As with full-length rRNA surveys, each sequence read is a tag surrogate for a single microbe. However, rather than assigning taxonomy by creating gene trees de novo that include all experimental sequences and certain reference taxa, we compare the hypervariable region tags to an extensive database of rRNA sequences and assign taxonomy based on the best match in a Global Alignment for Sequence Taxonomy (GAST process. The resulting taxonomic census provides information on both composition and diversity of the microbial community. To determine the effectiveness of using only hypervariable region tags for assessing microbial community membership, we compared the taxonomy assigned to the V3 and V6 hypervariable regions with the taxonomy assigned to full-length SSU rRNA sequences isolated from both the human gut and a deep-sea hydrothermal vent. The hypervariable region tags and full-length rRNA sequences provided equivalent taxonomy and measures of relative abundance of microbial communities, even for tags up to 15% divergent from their nearest reference match. The greater sampling depth per dollar afforded by massively parallel pyrosequencing reveals many more members of the "rare biosphere" than does capillary sequencing of the full-length gene. In addition, tag sequencing eliminates cloning bias and the sequences are short enough to be completely sequenced in a single read, maximizing the number of organisms sampled in a run while minimizing chimera formation. This technique allows the cost-effective exploration of changes in microbial community structure, including the rare biosphere, over space and time and can be applied immediately to initiatives, such as the Human Microbiome Project.

  1. Effect of Secondary Doping Using Sorbitol on Structure and Transport Properties of PEDOT-PSS Thin Films

    Science.gov (United States)

    Khasim, Syed; Pasha, Apsar; Roy, Aashish S.; Parveen, Ameena; Badi, Nacer

    2017-07-01

    Poly(3,4-ethylene dioxythiophene):poly(styrenesulphonate) (PEDOT-PSS) in the recent past has emerged as one of the most fascinating conducting polymers for many device applications. The unique feature of PEDOT-PSS is its transparency in the entire visible spectrum with excellent thermal stability. The PEDOT-PSS as prepared as an aqueous dispersion has very low conductivity, and it hinders the performance of a device. In this work we report the conductivity enhancement of PEDOT-PSS thin films through secondary doping using a polar organic solvent such as sorbitol. The mechanism of conductivity enhancement was studied through various physical and chemical characterizations. The effect of sorbitol concentration on structure and transport properties of PEDOT-PSS thin films was investigated in detail. The structural and morphological modifications in PEDOT-PSS due to the addition of sorbitol was studied through Fourier transform spectroscopy, Ultra Violet-visible spectroscopy, theromogravimetric analysis, scanning electron microscopy and atomic force microscopy. The interactions resulting from conformational changes of PEDOT chains that changes from coiled to linear structure due to the sorbitol treatment significantly improves the conductivity of PEDOT-PSS films. The secondary doping of sorbitol reduces the energy barrier that facilitates the charge carrier hopping leading to enhanced conductivity. We have observed that the conductivity of PEDOT-PSS thin films was increased by two fold due to sorbitol treatment when compared to conductivity of pure PEDOT-PSS. We have carried out detailed analysis of dielectric parameters of sorbitol-treated PEDOT-PSS films and found that sorbitol treatment has a significant effect on various dielectric attributes of PEDOT-PSS films. Hence, secondary doping using sorbitol could be a useful way to effectively tailor the conductivity and dielectric properties of PEDOT-PSS thin films that can be used as flexible electrodes in

  2. ITS2 secondary structure improves phylogeny estimation in a radiation of blue butterflies of the subgenus Agrodiaetus (Lepidoptera: Lycaenidae: Polyommatus

    Directory of Open Access Journals (Sweden)

    Wolf Matthias

    2009-12-01

    Full Text Available Abstract Background Current molecular phylogenetic studies of Lepidoptera and most other arthropods are predominantly based on mitochondrial genes and a limited number of nuclear genes. The nuclear genes, however, generally do not provide sufficient information for young radiations. ITS2 , which has proven to be an excellent nuclear marker for similarly aged radiations in other organisms like fungi and plants, is only rarely used for phylogeny estimation in arthropods, although universal primers exist. This is partly due to difficulties in the alignment of ITS2 sequences in more distant taxa. The present study uses ITS2 secondary structure information to elucidate the phylogeny of a species-rich young radiation of arthropods, the butterfly subgenus Agrodiaetus. One aim is to evaluate the efficiency of ITS2 to resolve the phylogeny of the subgenus in comparison with COI , the most important mitochondrial marker in arthropods. Furthermore, we assess the use of compensatory base changes in ITS2 for the delimitation of species and discuss the prospects of ITS2 as a nuclear marker for barcoding studies. Results In the butterfly family Lycaenidae, ITS2 secondary structure enabled us to successfully align sequences of different subtribes in Polyommatini and produce a Profile Neighbour Joining tree of this tribe, the resolution of which is comparable to phylogenetic trees obtained with COI+COII . The subgenus Agrodiaetus comprises 6 major clades which are in agreement with COI analyses. A dispersal-vicariance analysis (DIVA traced the origin of most Agrodiaetus clades to separate biogeographical areas in the region encompassing Eastern Anatolia, Transcaucasia and Iran. Conclusions With the inclusion of secondary structure information, ITS2 appears to be a suitable nuclear marker to infer the phylogeny of young radiations, as well as more distantly related genera within a diverse arthropod family. Its phylogenetic signal is comparable to the

  3. ITS2 secondary structure improves phylogeny estimation in a radiation of blue butterflies of the subgenus Agrodiaetus (Lepidoptera: Lycaenidae: Polyommatus ).

    Science.gov (United States)

    Wiemers, Martin; Keller, Alexander; Wolf, Matthias

    2009-12-26

    Current molecular phylogenetic studies of Lepidoptera and most other arthropods are predominantly based on mitochondrial genes and a limited number of nuclear genes. The nuclear genes, however, generally do not provide sufficient information for young radiations. ITS2 , which has proven to be an excellent nuclear marker for similarly aged radiations in other organisms like fungi and plants, is only rarely used for phylogeny estimation in arthropods, although universal primers exist. This is partly due to difficulties in the alignment of ITS2 sequences in more distant taxa. The present study uses ITS2 secondary structure information to elucidate the phylogeny of a species-rich young radiation of arthropods, the butterfly subgenus Agrodiaetus. One aim is to evaluate the efficiency of ITS2 to resolve the phylogeny of the subgenus in comparison with COI , the most important mitochondrial marker in arthropods. Furthermore, we assess the use of compensatory base changes in ITS2 for the delimitation of species and discuss the prospects of ITS2 as a nuclear marker for barcoding studies. In the butterfly family Lycaenidae, ITS2 secondary structure enabled us to successfully align sequences of different subtribes in Polyommatini and produce a Profile Neighbour Joining tree of this tribe, the resolution of which is comparable to phylogenetic trees obtained with COI+COII . The subgenus Agrodiaetus comprises 6 major clades which are in agreement with COI analyses. A dispersal-vicariance analysis (DIVA) traced the origin of most Agrodiaetus clades to separate biogeographical areas in the region encompassing Eastern Anatolia, Transcaucasia and Iran. With the inclusion of secondary structure information, ITS2 appears to be a suitable nuclear marker to infer the phylogeny of young radiations, as well as more distantly related genera within a diverse arthropod family. Its phylogenetic signal is comparable to the mitochondrial marker COI . Compensatory base changes are very rare

  4. Mineral Association Changes the Secondary Structure and Dynamics of Murine Amelogenin

    Energy Technology Data Exchange (ETDEWEB)

    Lu, J. X.; Xu, Y. S.; Buchko, G. W.; Shaw, W. J.

    2013-10-15

    Biomineralization proteins, present during the formation of hard tissues including bones, teeth, egg shells and nacre, result in the exquisite structures and properties of the resulting materials.[1] The structure of these proteins is often implicated in the control of the mineral properties, however very little structural data is available for the bulk of these proteins due to the difficulty in determining structures of immobilized proteins. Solid-state NMR is uniquely suited to the study of the structure of proteins bound to surfaces, demonstrated with the structural and orientation insights provided for the hydroxyapatite mineralization proteins statherin and the amelogenin, LRAP.[2] While these data are some of the only structural data available for this important class of protein, the experiments are often expensive and time consuming, due to the need to prepare and measure samples with isolated spin pairs, and are limited to a size of ~60 residues. In this work, we utilized a combination of 1D and recent 2D[3] solid-state NMR techniques along with a sparsely labelled sample to characterize the structure and dynamics of potential HAP binding residues of the 180 residue enamel protein, amelogenin. Amelogenin nanospheres and mineral bound amelogenin were investigated and a shift from unstructured to β-sheet structure was observed, along with a decrease in protein flexibility. This work provides the first molecular level structure and dynamic information of full-length amelogenin on the surface of hydroxyapatite (HAP) and within nanospheres, and demonstrates the ability to evaluate structural characteristics of large biomineralization proteins bound to their physiologically relevant surface. The research was performed at the Pacific Northwest National Laboratory (PNNL), a facility operated by Battelle for the U.S. Department of Energy, with a portion of it performed at the W.R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a national scientific user

  5. Hong Kong Secondary School Students' Attitudes towards Science: A Study of Structural Models and Gender Differences

    Science.gov (United States)

    Wan, Zhi Hong; Lee, John Chi Kin

    2017-01-01

    This study explored two under-researched areas on students' attitudes towards science, that is, the structural models representing these attitudes and the role played by school bands in moderating the gender differences in such attitudes. The participants were 360 ninth graders in Hong Kong from 3 school bands. The structural equation modelling…

  6. RNAsnp: efficient detection of local RNA secondary structure changes induced by SNPs

    DEFF Research Database (Denmark)

    Radhakrishnan, Sabarinathan; Tafer, Hakim; Seemann, Ernst Stefan

    2013-01-01

    Structural characteristics are essential for the functioning of many noncoding RNAs and cis-regulatory elements of mRNAs. SNPs may disrupt these structures, interfere with their molecular function, and hence cause a phenotypic effect. RNA folding algorithms can provide detailed insights into stru...

  7. On the secondary charging effects and structure of mesospheric dust particles impacting on rocket probes

    Energy Technology Data Exchange (ETDEWEB)

    Havnes, O.; Naesheim, L.I. [Inst. of Physics, Univ. of Tromso (Norway)

    2007-07-01

    The dust probe DUSTY, first launched during the summer of 1994 (flights ECT-02 and ECT-07) from Andoeya Rocket Range, northern Norway, was the first probe to unambiguously detect heavy charged mesospheric aerosols, from hereon referred to as dust. In ECT-02 the probe detected negatively charged dust particles in the height interval of 83 to 88.5 km. In this flight, the lower grid in the detector (Grid 2) measures both positive and negative currents in various regions, and we find that the relationship between the current measurements of Grid 2 and the bottom plate can only be explained by influence from secondary charge production on Grid 2. In ECT-07, which had a large coning, positive currents reaching the top grid of the probe were interpreted as due to the impact of positively charged dust particles. We have now reanalyzed the data from ECT-07 and arrived at the conclusion that the measured positive currents to this grid must have been mainly due to secondary charging effects from the impacting dust particles. The grid consists of a set of parallel wires crossed with an identical set of wires on top of it, and we find that if the observed currents were created from the direct impact of charged dust particles, then they should be very weakly modulated at four times the rocket spin rate {omega}{sub R}. Observations show, however, that the observed currents are strongly modulated at 2{omega}{sub R}. We cannot reproduce the observed large modulations of the impact currents in the dust layer if the currents are due only to the transfer of the charges on the impacted dust particles. Based on the results of recent ice cluster impact secondary charging experiments by Tomsic (2003), which found that a small fraction of the ice clusters, when impacting with nearly grazing incidence, carried away one negative charge - 1e, we have arrived at the conclusion that similar, but significantly more effective, charging effects must be predominantly responsible for the positive

  8. Carbon Policy and Technical Change: Market Structure, Increasing Returns, and Secondary Benefits. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Peretto, P.; Smith, V. K.

    2001-11-19

    An economic evaluation of the impact of policies intended to control emissions of CO{sub 2} and other ''greenhouse gases'' (GHGS) depends on the net costs of these controls and their distribution throughout the production sectors of developed and developing economics. The answers derived from appraisals of these net costs, in turn, stem from what is assumed about the timing of the controls, the pace of technological change, and any short-term secondary benefits from their control. There have only been a few serious attempts to estimate the economic benefits from the policies associated with such long run outcomes. All of the approaches to date have made fairly strong assumptions or relied on contingent valuation estimates of hypothetical situations.

  9. FRAMEWORK FOR STRUCTURAL ONLINE HEALTH MONITORING OF AGING AND DEGRADATION OF SECONDARY PIPING SYSTEMS DUE TO SOME ASPECTS OF EROSION

    Energy Technology Data Exchange (ETDEWEB)

    Gribok, Andrei V.; Agarwal, Vivek

    2017-06-01

    This paper describes the current state of research related to critical aspects of erosion and selected aspects of degradation of secondary components in nuclear power plants (NPPs). The paper also proposes a framework for online health monitoring of aging and degradation of secondary components. The framework consists of an integrated multi-sensor modality system, which can be used to monitor different piping configurations under different degradation conditions. The report analyses the currently known degradation mechanisms and available predictive models. Based on this analysis, the structural health monitoring framework is proposed. The Light Water Reactor Sustainability Program began to evaluate technologies that could be used to perform online monitoring of piping and other secondary system structural components in commercial NPPs. These online monitoring systems have the potential to identify when a more detailed inspection is needed using real time measurements, rather than at a pre-determined inspection interval. This transition to condition-based, risk-informed automated maintenance will contribute to a significant reduction of operations and maintenance costs that account for the majority of nuclear power generation costs. Furthermore, of the operations and maintenance costs in U.S. plants, approximately 80% are labor costs. To address the issue of rising operating costs and economic viability, in 2017, companies that operate the national nuclear energy fleet started the Delivering the Nuclear Promise Initiative, which is a 3 year program aimed at maintaining operational focus, increasing value, and improving efficiency. There is unanimous agreement between industry experts and academic researchers that identifying and prioritizing inspection locations in secondary piping systems (for example, in raw water piping or diesel piping) would eliminate many excessive in-service inspections. The proposed structural health monitoring framework takes aim at

  10. Evidences for Cooperative Resonance-Assisted Hydrogen Bonds in Protein Secondary Structure Analogs

    National Research Council Canada - National Science Library

    Yu Zhou; Geng Deng; Yan-zhen Zheng; Jing Xu; Hamad Ashraf; Zhi-wu Yu

    2016-01-01

    .... The structural origin of this cooperativity, however, is still under debate. Here we report a new investigation combining excess infrared spectroscopy and density functional theory calculation on peptide analogs, represented by N-methylformamide (NMF...

  11. Modeling proteins using a super-secondary structure library and NMR chemical shift information.

    Science.gov (United States)

    Menon, Vilas; Vallat, Brinda K; Dybas, Joseph M; Fiser, Andras

    2013-06-04

    A remaining challenge in protein modeling is to predict structures for sequences with no sequence similarity to any experimentally solved structure. Based on earlier observations, the library of protein backbone supersecondary structure motifs (Smotifs) saturated about a decade ago. Therefore, it should be possible to build any structure from a combination of existing Smotifs with the help of limited experimental data that are sufficient to relate the backbone conformations of Smotifs between target proteins and known structures. Here, we present a hybrid modeling algorithm that relies on an exhaustive Smotif library and on nuclear magnetic resonance chemical shift patterns without any input of primary sequence information. In a test of 102 proteins, the algorithm delivered 90 homology-model-quality models, among them 24 high-quality ones, and a topologically correct solution for almost all cases. The current approach opens a venue to address the modeling of larger protein structures for which chemical shifts are available. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. A regime map for secondary flow structures under physiological and multi-harmonic inflow through a bent tube model for curved arteries

    Science.gov (United States)

    Callahan, Shannon M.; Caldwell, Kirin; Bulusu, Kartik V.; Plesniak, Michael W.

    2012-11-01

    Secondary flow structures are known to affect wall shear stress, which is closely related to atherogenesis and drug particle deposition. A regime map provides a framework to examine phase-wise variations in secondary flow structures under physiological and multi-harmonic inflow waveforms under conditions of a fixed Womersley number (4.2) and curvature ratio (1/7). Experimental PIV data were acquired at the 90-degree location in a 180-degree curved test section of a bent tube model for curved arteries using a blood analog working fluid. Coherent structure detection was performed using a continuous wavelet transform algorithm (PIVlet 1.2) and further analysis was carried out by grouping similar secondary flow structures at a fixed secondary Reynolds numbers. Phase-locked, planar vorticity fields over one period of inflow waveform revealed size, structure and strength similarities in secondary flow morphologies during the acceleration and deceleration phases. The utility of the new regime map lies in the a priori identification of pulsatile secondary flow structures, eliminating the need for exhaustive experimentation or computing, requiring only flow rate measurements that are easily acquired under clinical conditions. Supported by the National Science Foundation, Grant No. CBET-0828903 and GW Center for Biomimetics and Bioinspired Engineering (COBRE).

  13. miR-Explore: Predicting MicroRNA Precursors by Class Grouping and Secondary Structure Positional Alignment

    Science.gov (United States)

    Sebastian, Bram; Aggrey, Samuel E.

    2013-01-01

    MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expressions by targeting the mRNAs especially in the 3′UTR regions. The identification of miRNAs has been done by biological experiment and computational prediction. The computational prediction approach has been done using two major methods: comparative and noncomparative. The comparative method is dependent on the conservation of the miRNA sequences and secondary structure. The noncomparative method, on the other hand, does not rely on conservation. We hypothesized that each miRNA class has its own unique set of features; therefore, grouping miRNA by classes before using them as training data will improve sensitivity and specificity. The average sensitivity was 88.62% for miR-Explore, which relies on within miRNA class alignment, and 70.82% for miR-abela, which relies on global alignment. Compared with global alignment, grouping miRNA by classes yields a better sensitivity with very high specificity for pre-miRNA prediction even when a simple positional based secondary and primary structure alignment are used. PMID:23645986

  14. Atypical origin, structure and arrangement of secondary tracheary elements in the stem of the monocotyledonous dragon tree, Dracaena draco.

    Science.gov (United States)

    Jura-Morawiec, Joanna

    2017-01-01

    Tracheary elements within the secondary body of a dragon tree shared features characteristic of fibres. Their considerable intrusive growth resulted in a rigid network with a braid-like arrangement which contributes towards the tree-like form of the plant. Monocot cambium gives rise to xylem and phloem which become organized into vascular bundles. The xylem consists entirely of tracheids, and these undergo considerable intrusive elongation during their development, unlike the tracheids of conifers and those of vesselless dicotyledons. Monocot tracheids have not been fully investigated, and our understanding of their structure is incomplete. Therefore, in this study the degree of variation in the structure and arrangement of secondary tracheary elements of monocots were determined, based on the Dracaena draco stem. In addition, its mechanical and physiological implications were discussed. Analysis of series of thin serial sections and macerations of the immature and fully developed tracheids showed that the course of intrusive elongation of tracheids was determined by the spatial relationship that exists between the growing tracheid and surrounding cells, and was not usually parallel to the stem axis. It influenced the shape of tracheids, as well the cross-sectional shape of vascular bundles. Tracheids become twisted or even interwoven and so, their ends do not join with the ends of other tracheids. The complexity of the tracheid network, that functions both in transport and mechanical support, seems to have a major impact on the tree-like growth habit of D. draco.

  15. Pseudoknot in domain II of 23 S rRNA is essential for ribosome function

    DEFF Research Database (Denmark)

    Rosendahl, G; Hansen, L H; Douthwaite, S

    1995-01-01

    of these base-pairs is disrupted, and it is completely abolished upon disruption of both base-pairs. Each mutant 23 S rRNA is assembled into 50 S subunits, but the mutant subunits do not stably interact with 30 S to engage in protein synthesis. Enzymatic and chemical probing of ribosomal particles reveals...... and ribosomes, but is rendered unreactive when either the pseudoknot is broken or when the r-proteins are removed. The structure of the pseudoknot region is possibly influenced by interaction of an r-protein at or close to the pseudoknot. Re-establishing the pseudoknot Watson-Crick interactions with one...... "eukaryal" (1005G.1138C or 1006U.1137A) pair and one "bacterial" C.G pair largely restores the structure and function of the rRNA. Bacterial ribosomes containing both these eukaryal pairs also participate in protein synthesis, although at much reduced efficiency, and the structure of their pseudoknot region...

  16. The relationship between professional preparation and class structure on health instruction in the secondary classroom.

    Science.gov (United States)

    Hammig, Bart; Ogletree, Roberta; Wycoff-Horn, Marcie R

    2011-09-01

    The aim of the present study was to examine the impact of professional preparation and class structure on health content delivery and time spent delivering content among required health education classes in the United States. Data from the classroom-level file of the 2006 School Health Policies and Programs Study were utilized. A series of multivariable logistic regression models were employed to determine if instruction of content was dependent on professional preparation and/or class structure. Years of teaching health topics and size of the school district were included as covariates in the multivariable logistic models. We also conducted a multivariable logistic regression model to examine if time spent teaching each topic area was dependent upon professional preparation and/or class structure. Findings indicated that professionally prepared teachers were significantly more likely to deliver content in 6 of 12 health topic areas when compared to untrained teachers. Class structure was also an important predictor of content delivery among many topic areas. Teachers who taught classes that were devoted to health instruction were significantly more likely to deliver content in the following topic areas: alcohol/drug prevention, tobacco prevention, sexuality, pregnancy, human immuno virus and sexually transmitted disease prevention, emotional/mental health and suicide, and violence prevention. Research concerning the relationship between professional preparation and teaching outcomes is scant. The present study indicates that health content coverage and time spent on instruction are associated with both professional preparation and class structure for many health content areas. © 2011, American School Health Association.

  17. Secondary structure, a missing component of sequence-based minimotif definitions.

    Directory of Open Access Journals (Sweden)

    David P Sargeant

    Full Text Available Minimotifs are short contiguous segments of proteins that have a known biological function. The hundreds of thousands of minimotifs discovered thus far are an important part of the theoretical understanding of the specificity of protein-protein interactions, posttranslational modifications, and signal transduction that occur in cells. However, a longstanding problem is that the different abstractions of the sequence definitions do not accurately capture the specificity, despite decades of effort by many labs. We present evidence that structure is an essential component of minimotif specificity, yet is not used in minimotif definitions. Our analysis of several known minimotifs as case studies, analysis of occurrences of minimotifs in structured and disordered regions of proteins, and review of the literature support a new model for minimotif definitions that includes sequence, structure, and function.

  18. Development of Successive Cambia and Structure of Secondary Xylem of Ipomoea Obscura (Convolvulaceae

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    Rajput Kishore S.

    2014-07-01

    Full Text Available Stems of Ipomoea obscura Ker Gawl., increase in thickness by forming multiple rings of cambia. Stems 5-6 mm thick produce parenchymatous derivatives which divide repeatedly to form small arcs of cambium. Several such small arcs initiate simultaneously and form a ring of small cambial arcs. After the formation of a few xylem and phloem elements, all these arcs are interconnected by transdifferentiation of parenchyma cells present between the cambial arcs and constitute a complete cambial cylinder. This newly formed cambium is functionally bidirectional: earlier- formed arcs produce xylem centripetally and phloem centrifugally, while later-formed segments exclusively produce thin-walled parenchyma cells on either side. Young stems are circular in cross section but as stem thickness increases they become oval to elliptic or lobed and dumbbell-shaped. Xylem rays are mostly uni- or biseriate and thin-walled, but multiseriate rays characteristic for a climbing habit are observed occasionally. In thick stems, the marginal ray parenchyma in most of the samples becomes meristematic and develops ray cambia which exclusively produce sieve elements. Similarly, parenchyma cells produced from later-formed cambial segments give rise to several irregularly oriented vascular bundles. The secondary xylem is diffuse porous, with indistinct growth rings and is composed of fibriform and wider vessels, fibres, and axial and ray parenchyma cells, while phloem consists of sieve elements, companion cells, and axial and ray parenchyma cells.

  19. Occurrence of fragmented 16S rRNA in an obligate bacterial endosymbiont of Paramecium caudatum.

    Science.gov (United States)

    Springer, N; Ludwig, W; Amann, R; Schmidt, H J; Görtz, H D; Schleifer, K H

    1993-01-01

    The phylogenetic position of Caedibacter caryophila, a so far noncultured killer symbiont of Paramecium caudatum, was elucidated by comparative sequence analysis of in vitro amplified 16S rRNA genes (rDNA). C. caryophila is a member of the alpha subclass of the Proteobacteria phylum. Within this subclass C. caryophila is moderately related to Holospora obtusa, which is another obligate endosymbiont of Paramecium caudatum, and to Rickettsia. A 16S rRNA targeted specific hybridization probe was designed and used for in situ detection of C. caryophila within its host cell. Comparison of the 16S rDNA primary structure of C. caryophila with homologous sequences from other bacteria revealed an unusual insertion of 194 base pairs within the 5'-terminal part of the corresponding gene. The intervening sequence is not present in mature 16S rRNA of C. caryophila. It was demonstrated that C. caryophila contained fragmented 16S rRNA. Images Fig. 5 Fig. 6 PMID:8234331

  20. Dynamic changes in the secondary structure of ECE-1 and XCE account for their different substrate specificities

    Directory of Open Access Journals (Sweden)

    Ul-Haq Zaheer

    2012-11-01

    Full Text Available Abstract Background X-converting enzyme (XCE involved in nervous control of respiration, is a member of the M13 family of zinc peptidases, for which no natural substrate has been identified yet. In contrast, it’s well characterized homologue endothelin-converting enzyme-1 (ECE-1 showed broad substrate specificity and acts as endopeptidase as well as dipeptidase. To explore the structural differences between XCE and ECE-1, homology model of XCE was built using the complex structure of ECE-1 with phosphoramidon (pdb-id: 3DWB as template. Phosphoramidon was docked into the binding site of XCE whereas phosphate oxygen of the inhibitor was used as water molecule to design the apo forms of both enzymes. Molecular dynamics simulation of both enzymes was performed to analyze the dynamic nature of their active site residues in the absence and presence of the inhibitor. Results Homology model of XCE explained the role of non-conserved residues of its S2’ subsite. Molecular dynamics (MD simulations identified the flexible transitions of F149/I150, N566/N571, W714/W719, and R145/R723 residues of ECE-1/XCE for the strong binding of the inhibitor. Secondary structure calculations using DSSP method reveals the folding of R145/R723 residue of ECE-1/XCE into β-sheet structure while unfolding of the S2’ subsite residues in aECE-1 and sustained compact folding of that of aXCE. The results evaluated are in good agreement with available experimental data, thus providing detailed molecular models which can explain the structural and specificities differences between both zinc peptidases. Conclusions Secondary structure changes of both enzymes during the simulation time revealed the importance of β-sheet structure of R145/R723 for its binding with the terminal carboxylate group of the inhibitor. Unfolding of the α-helix comprising the S2’ subsite residues in aECE-1 correlate well with its endopeptidase activity while their compact folding in aXCE may

  1. The Use of Structural Behavioral Assessment to Develop Interventions for Secondary Students Exhibiting Challenging Behaviors

    Science.gov (United States)

    Losinski, Mickey; Maag, John W.; Katsiyannis, Antonis; Ryan, Joseph B.

    2015-01-01

    Structural behavioral assessment (SBA) involves a series of heuristic approaches similar to those used with functional behavioral assessment (FBA). It involves assessing contextual variables that precede the occurrence of a behavior. These variables have also been termed antecedents, setting events, or establishing operations. Once these variables…

  2. CHANGES IN EARTHWORM DENSITY AND COMMUNITY STRUCTURE DURING SECONDARY SUCCESSION IN ABANDONED TROPICAL PASTURES

    Science.gov (United States)

    Xiaoming Zou; Grizelle Gonzalez

    1997-01-01

    Plant community succession alters the quantity and chemistry of organic inputs to soils. These differences in organic input may trigger changes in soil fertility and fauna1 activity. We examined earthworm density and community structure along a successional sequence of plant communities in abandoned tropical pastures in Puerto Rico. The chronological sequence of these...

  3. New Comparative Analysis Based on the Secondary Structure of SSU-rRNA Gene Reveals the Evolutionary Trend and the Family-Genus Characters of Mobilida (Ciliophora, Peritrichia).

    Science.gov (United States)

    Zhang, Yong; Zhao, Yuan-Jun; Wang, Qin; Tang, Fa-Hui

    2015-08-01

    In order to reveal the structural evolutionary trend of Mobilida ciliates, twenty-six SSU-rRNA sequences of mobilid species, including seven ones newly sequenced in the present work, were used for comparative phylogenic analysis based on the RNA secondary structure. The research results indicate that all the secondary structures except domains Helix 10, Helix 12, and Helix 37 could be regarded as the criterions in classification between the family Trichodinidae and Urceolariida, and four regions including Helix E10-1, Helix 29, Helix 43, and Helix 45-Helix 46 could be as criterions in classification between the genus Trichodinella and Trichodina in family Trichodinidae. After the analysis of common structural feature within the Mobilida, it was found that the secondary structure of V6 could prove the family Urceolariidae primitive status. This research has further suggested that the genus Trichodina could be divergent earlier than Trichodinella in the family Trichodinidae. In addition, the relationship between the secondary structure and topology of phylogenic tree that the branching order of most clades corresponds with the secondary structure of species within each clade of phylogenetic tree was first uncovered and discussed in the present study.

  4. MxaJ structure reveals a periplasmic binding protein-like architecture with unique secondary structural elements.

    Science.gov (United States)

    Myung Choi, Jin; Cao, Thinh-Phat; Wouk Kim, Si; Ho Lee, Kun; Haeng Lee, Sung

    2017-07-01

    MxaJ is a component of type II methanol dehydrogenase (MDH) that mediates electron transfer during methanol oxidation in methanotrophic bacteria. However, little is known about how MxaJ structurally cooperates with MDH and Cytochrome c L . Here, we report for the first time the crystal structure of MxaJ. MxaJ consists of eight α-helices and six β-strands, and resembles the "bi-lobate" folding architecture found in periplasmic binding proteins. Distinctive features of MxaJ include prominent loops and a β-strand around the hinge region supporting the ligand-binding cavity, which might provide a more favorable framework for interacting with proteins rather than small molecules. Proteins 2017; 85:1379-1386. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  5. Novel evolutionary lineages revealed in the Chaetothyriales (fungi based on multigene phylogenetic analyses and comparison of its secondary structure.

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    Martina Réblová

    Full Text Available Cyphellophora and Phialophora (Chaetothyriales, Pezizomycota comprise species known from skin infections of humans and animals and from a variety of environmental sources. These fungi were studied based on the comparison of cultural and morphological features and phylogenetic analyses of five nuclear loci, i.e., internal transcribed spacer rDNA operon (ITS, large and small subunit nuclear ribosomal DNA (nuc28S rDNA, nuc18S rDNA, β-tubulin, DNA replication licensing factor (mcm7 and second largest subunit of RNA polymerase II (rpb2. Phylogenetic results were supported by comparative analysis of ITS1 and ITS2 secondary structure of representatives of the Chaetothyriales and the identification of substitutions among the taxa analyzed. Base pairs with non-conserved, co-evolving nucleotides that maintain base pairing in the RNA transcript and unique evolutionary motifs in the ITS2 that characterize whole clades or individual taxa were mapped on predicted secondary structure models. Morphological characteristics, structural data and phylogenetic analyses of three datasets, i.e., ITS, ITS-β-tubulin and 28S-18S-rpb2-mcm7, define a robust clade containing eight species of Cyphellophora (including the type and six species of Phialophora. These taxa are now accommodated in the Cyphellophoraceae, a novel evolutionary lineage within the Chaetothyriales. Cyphellophora is emended and expanded to encompass species with both septate and nonseptate conidia formed on discrete, intercalary, terminal or lateral phialides. Six new combinations in Cyphellophora are proposed and a dichotomous key to species accepted in the genus is provided. Cyphellophora eugeniae and C. hylomeconis, which grouped in the Chaetothyriaceae, represent another novel lineage and are introduced as the type species of separate genera.

  6. Noncanonical secondary structure stabilizes mitochondrial tRNA(Ser(UCN)) by reducing the entropic cost of tertiary folding.

    Science.gov (United States)

    Mustoe, Anthony M; Liu, Xin; Lin, Paul J; Al-Hashimi, Hashim M; Fierke, Carol A; Brooks, Charles L

    2015-03-18

    Mammalian mitochondrial tRNA(Ser(UCN)) (mt-tRNA(Ser)) and pyrrolysine tRNA (tRNA(Pyl)) fold to near-canonical three-dimensional structures despite having noncanonical secondary structures with shortened interhelical loops that disrupt the conserved tRNA tertiary interaction network. How these noncanonical tRNAs compensate for their loss of tertiary interactions remains unclear. Furthermore, in human mt-tRNA(Ser), lengthening the variable loop by the 7472insC mutation reduces mt-tRNA(Ser) concentration in vivo through poorly understood mechanisms and is strongly associated with diseases such as deafness and epilepsy. Using simulations of the TOPRNA coarse-grained model, we show that increased topological constraints encoded by the unique secondary structure of wild-type mt-tRNA(Ser) decrease the entropic cost of folding by ∼2.5 kcal/mol compared to canonical tRNA, offsetting its loss of tertiary interactions. Further simulations show that the pathogenic 7472insC mutation disrupts topological constraints and hence destabilizes the mutant mt-tRNA(Ser) by ∼0.6 kcal/mol relative to wild-type. UV melting experiments confirm that insertion mutations lower mt-tRNA(Ser) melting temperature by 6-9 °C and increase the folding free energy by 0.8-1.7 kcal/mol in a largely sequence- and salt-independent manner, in quantitative agreement with our simulation predictions. Our results show that topological constraints provide a quantitative framework for describing key aspects of RNA folding behavior and also provide the first evidence of a pathogenic mutation that is due to disruption of topological constraints.

  7. Novel sequence variations in LAMA2 and SGCG genes modulating cis-acting regulatory elements and RNA secondary structure

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    Olfa Siala

    2010-01-01

    Full Text Available In this study, we detected new sequence variations in LAMA2 and SGCG genes in 5 ethnic populations, and analysed their effect on enhancer composition and mRNA structure. PCR amplification and DNA sequencing were performed and followed by bioinformatics analyses using ESEfinder as well as MFOLD software. We found 3 novel sequence variations in the LAMA2 (c.3174+22_23insAT and c.6085 +12delA and SGCG (c.*102A/C genes. These variations were present in 210 tested healthy controls from Tunisian, Moroccan, Algerian, Lebanese and French populations suggesting that they represent novel polymorphisms within LAMA2 and SGCG genes sequences. ESEfinder showed that the c.*102A/C substitution created a new exon splicing enhancer in the 3'UTR of SGCG genes, whereas the c.6085 +12delA deletion was situated in the base pairing region between LAMA2 mRNA and the U1snRNA spliceosomal components. The RNA structure analyses showed that both variations modulated RNA secondary structure. Our results are suggestive of correlations between mRNA folding and the recruitment of spliceosomal components mediating splicing, including SR proteins. The contribution of common sequence variations to mRNA structural and functional diversity will contribute to a better study of gene expression.

  8. Membrane interaction and secondary structure of de novo designed arginine-and tryptophan peptides with dual function

    KAUST Repository

    Rydberg, Hanna A.

    2012-10-01

    Cell-penetrating peptides and antimicrobial peptides are two classes of positively charged membrane active peptides with several properties in common. The challenge is to combine knowledge about the membrane interaction mechanisms and structural properties of the two classes to design peptides with membrane-specific actions, useful either as transporters of cargo or as antibacterial substances. Membrane active peptides are commonly rich in arginine and tryptophan. We have previously designed a series of arg/trp peptides and investigated how the position and number of tryptophans affect cellular uptake. Here we explore the antimicrobial properties and the interaction with lipid model membranes of these peptides, using minimal inhibitory concentrations assay (MIC), circular dichroism (CD) and linear dichroism (LD). The results show that the arg/trp peptides inhibit the growth of the two gram positive strains Staphylococcus aureus and Staphylococcus pyogenes, with some individual variations depending on the position of the tryptophans. No inhibition of the gram negative strains Proteus mirabilis or Pseudomonas aeruginosa was noticed. CD indicated that when bound to lipid vesicles one of the peptides forms an α-helical like structure, whereas the other five exhibited rather random coiled structures. LD indicated that all six peptides were somehow aligned parallel with the membrane surface. Our results do not reveal any obvious connection between membrane interaction and antimicrobial effect for the studied peptides. By contrast cell-penetrating properties can be coupled to both the secondary structure and the degree of order of the peptides. © 2012 Elsevier Inc.

  9. Secondary structure, dynamics, and architecture of the p7 membrane protein from hepatitis C virus by NMR spectroscopy.

    Science.gov (United States)

    Cook, Gabriel A; Opella, Stanley J

    2011-06-01

    P7 is a small membrane protein that is essential for the infectivity of hepatitis C virus. Solution-state NMR experiments on p7 in DHPC micelles, including hydrogen/deuterium exchange, paramagnetic relaxation enhancement and bicelle 'q-titration,' demonstrate that the protein has a range of dynamic properties and distinct structural segments. These data along with residual dipolar couplings yield a secondary structure model of p7. We were able to confirm previous proposals that the protein has two transmembrane segments with a short interhelical loop containing the two basic residues K33 and R35. The 63-amino acid protein has a remarkably complex structure made up of seven identifiable sections, four of which are helical segments with different tilt angles and dynamics. A solid-state NMR two-dimensional separated local field spectrum of p7 aligned in phospholipid bilayers provided the tilt angles of two of these segments. A preliminary structural model of p7 derived from these NMR data is presented. Copyright © 2010 Elsevier B.V. All rights reserved.

  10. Secondary structure of cell-penetrating peptides during interaction with fungal cells.

    Science.gov (United States)

    Gong, Zifan; Ikonomova, Svetlana P; Karlsson, Amy J

    2017-12-16

    Cell-penetrating peptides (CPPs) are peptides that cross cell membranes, either alone or while carrying molecular cargo. Although their interactions with mammalian cells have been widely studied, much less is known about their interactions with fungal cells, particularly at the biophysical level. We analyzed the interactions of seven CPPs (penetratin, Pep-1, MPG, pVEC, TP-10, MAP, and cecropin B) with the fungal pathogen Candida albicans using experiments and molecular simulations. Circular dichroism (CD) of the peptides revealed a structural transition from a random coil or weak helix to an α-helix occurs for all peptides when the solvent is changed from aqueous to hydrophobic. However, CD performed in the presence of C. albicans cells showed that proximity to the cell membrane is not necessarily sufficient to induce this structural transition, as penetratin, Pep-1, and MPG did not display a structural shift in the presence of cells. Monte Carlo simulations were performed to further probe the molecular-level interaction with the cell membrane, and these simulations suggested that pVEC, TP-10, MAP, and cecropin B strongly penetrate into the hydrophobic domain of the membrane lipid bilayer, inducing a transition to an α-helical conformation. In contrast, penetratin, Pep-1 and MPG remained in the hydrophilic region without a shift in conformation. The experimental data and MC simulations combine to explain how peptide structure affects their interaction with cells and their mechanism of translocation into cells (direct translocation vs. endocytosis). Our work also highlights the utility of combining biophysical experiments, biological experiments, and molecular modeling to understand biological phenomena. This article is protected by copyright. All rights reserved. © 2017 The Protein Society.

  11. Attitudes towards Mathematics at Secondary Level: Development and Structural Validation of the Scale for Assessing Attitudes towards Mathematics in Secondary Education (SAT-MAS)

    Science.gov (United States)

    Yáñez-Marquina, Lara; Villardón-Gallego, Lourdes

    2016-01-01

    Introduction: In secondary education, students' low achievement and engagement in mathematics are closely related to their attitudes towards the subject. Despite the international body of research, an exhaustive literature review of the existing instruments for measuring it draws attention to the inconsistency in the definition and corresponding…

  12. Effects of Secondary Plant Metabolites on Microbial Populations: Changes in Community Structure and Metabolic Activity in Contaminated Environments.

    Science.gov (United States)

    Musilova, Lucie; Ridl, Jakub; Polivkova, Marketa; Macek, Tomas; Uhlik, Ondrej

    2016-07-29

    Secondary plant metabolites (SPMEs) play an important role in plant survival in the environment and serve to establish ecological relationships between plants and other organisms. Communication between plants and microorganisms via SPMEs contained in root exudates or derived from litter decomposition is an example of this phenomenon. In this review, the general aspects of rhizodeposition together with the significance of terpenes and phenolic compounds are discussed in detail. We focus specifically on the effect of SPMEs on microbial community structure and metabolic activity in environments contaminated by polychlorinated biphenyls (PCBs) and polyaromatic hydrocarbons (PAHs). Furthermore, a section is devoted to a complex effect of plants and/or their metabolites contained in litter on bioremediation of contaminated sites. New insights are introduced from a study evaluating the effects of SPMEs derived during decomposition of grapefruit peel, lemon peel, and pears on bacterial communities and their ability to degrade PCBs in a long-term contaminated soil. The presented review supports the "secondary compound hypothesis" and demonstrates the potential of SPMEs for increasing the effectiveness of bioremediation processes.

  13. Large-scale analysis of secondary structure changes in proteins suggests a role for disorder-to-order transitions in nucleotide binding proteins.

    Science.gov (United States)

    Dan, Adi; Ofran, Yanay; Kliger, Yossef

    2010-02-01

    Conformational changes in proteins often involve secondary structure transitions. Such transitions can be divided into two types: disorder-to-order changes, in which a disordered segment acquires an ordered secondary structure (e.g., disorder to alpha-helix, disorder to beta-strand), and order-to-order changes, where a segment switches from one ordered secondary structure to another (e.g., alpha-helix to beta-strand, alpha-helix to turn). In this study, we explore the distribution of these transitions in the proteome. Using a comprehensive, yet highly conservative method, we compared solved three-dimensional structures of identical protein sequences, looking for differences in the secondary structures with which they were assigned. Protein chains in which such secondary structure transitions were detected, were classified into two sets according to the type of transition that is involved (disorder-to-order or order-to-order), allowing us to characterize each set by examining enrichment of gene ontology terms. The results reveal that the disorder-to-order set is significantly enriched with nucleotide binding proteins, whereas the order-to-order set is more diverse. Remarkably, further examination reveals that >22% of the purine nucleotide binding proteins include segments which undergo disorder-to-order transitions, suggesting that such transitions play an important role in this process. (c) 2009 Wiley-Liss, Inc.

  14. CHSalign: A Web Server That Builds upon Junction-Explorer and RNAJAG for Pairwise Alignment of RNA Secondary Structures with Coaxial Helical Stacking.

    Directory of Open Access Journals (Sweden)

    Lei Hua

    Full Text Available RNA junctions are important structural elements of RNA molecules. They are formed when three or more helices come together in three-dimensional space. Recent studies have focused on the annotation and prediction of coaxial helical stacking (CHS motifs within junctions. Here we exploit such predictions to develop an efficient alignment tool to handle RNA secondary structures with CHS motifs. Specifically, we build upon our Junction-Explorer software for predicting coaxial stacking and RNAJAG for modelling junction topologies as tree graphs to incorporate constrained tree matching and dynamic programming algorithms into a new method, called CHSalign, for aligning the secondary structures of RNA molecules containing CHS motifs. Thus, CHSalign is intended to be an efficient alignment tool for RNAs containing similar junctions. Experimental results based on thousands of alignments demonstrate that CHSalign can align two RNA secondary structures containing CHS motifs more accurately than other RNA secondary structure alignment tools. CHSalign yields a high score when aligning two RNA secondary structures with similar CHS motifs or helical arrangement patterns, and a low score otherwise. This new method has been implemented in a web server, and the program is also made freely available, at http://bioinformatics.njit.edu/CHSalign/.

  15. Oral microbiome profiles: 16S rRNA pyrosequencing and microarray assay comparison.

    Directory of Open Access Journals (Sweden)

    Jiyoung Ahn

    Full Text Available The human oral microbiome is potentially related to diverse health conditions and high-throughput technology provides the possibility of surveying microbial community structure at high resolution. We compared two oral microbiome survey methods: broad-based microbiome identification by 16S rRNA gene sequencing and targeted characterization of microbes by custom DNA microarray.Oral wash samples were collected from 20 individuals at Memorial Sloan-Kettering Cancer Center. 16S rRNA gene survey was performed by 454 pyrosequencing of the V3-V5 region (450 bp. Targeted identification by DNA microarray was carried out with the Human Oral Microbe Identification Microarray (HOMIM. Correlations and relative abundance were compared at phylum and genus level, between 16S rRNA sequence read ratio and HOMIM hybridization intensity.The major phyla, Firmicutes, Proteobacteria, Bacteroidetes, Actinobacteria, and Fusobacteria were identified with high correlation by the two methods (r = 0.70∼0.86. 16S rRNA gene pyrosequencing identified 77 genera and HOMIM identified 49, with 37 genera detected by both methods; more than 98% of classified bacteria were assigned in these 37 genera. Concordance by the two assays (presence/absence and correlations were high for common genera (Streptococcus, Veillonella, Leptotrichia, Prevotella, and Haemophilus; Correlation = 0.70-0.84.Microbiome community profiles assessed by 16S rRNA pyrosequencing and HOMIM were highly correlated at the phylum level and, when comparing the more commonly detected taxa, also at the genus level. Both methods are currently suitable for high-throughput epidemiologic investigations relating identified and more common oral microbial taxa to disease risk; yet, pyrosequencing may provide a broader spectrum of taxa identification, a distinct sequence-read record, and greater detection sensitivity.

  16. Predicted philogeny, secondary conformational structure, and epitope antigenicity of immunological sequences in poultry.

    Science.gov (United States)

    Lara, L J; Peconick, A P; Fassani, É J; Júnior, A M P; Chalfun, P R B; Raymundo, D L; Barçante, T A; Barçante, J M de P

    2017-05-18

    Poultry production is faced with different types of stresses that are responsible for issues of animal welfare as well as for economic losses. Moreover, the immunity decreases when animals are stressed. In silico analyses are important in reducing the cost and in increasing the accuracy of scientific results. A bioinformatics tool was used to perform ontology studies on 15 different immunological sequences of poultry. The mRNA structures and sequences with maximum antigenic residues were also predicted. No homology was found between the sequences of poultry and mammals. These results helped in the prediction of new potential molecular markers. Of the 15 sequences that were analyzed, predictions could not be made for five because they were longer than 2500 nucleotides; for the remaining 10 sequences, 20 conformational structures per sequence were predicted and the most stable sequences were identified by their minimum free energy values. The highest antigenic epitopes were accepted by the maximum scores; 15 of the total 8934 epitopes that were predicted were analyzed. These results would aid future studies that use synthetic peptides or recombinants as markers or immunomodulators and would expand our understanding on how stress can modulate the immune system. These would also help in developing rapid diagnostic tools, in increasing animal welfare, biosecurity, and productivity, and also in developing of food additives and environmental enrichment for stress control, thereby, making animal production more sustainable.

  17. The Factorial Structure and Psychometric Properties of Bullying Prevalence Questionnaire in Secondary Schools

    Directory of Open Access Journals (Sweden)

    Afzal Akbari-balootbangan

    2015-09-01

    Full Text Available Background and Objectives: Bullying has been common in schools across the world. Therefore, assessing the psychometric properties of its structures is important. The aim of this study was the assessment of the factorial structure and psychometric properties of bullying prevalence questionnaire. Materials and Methods: The present study was descriptive and psychometric. For this purpose, 400 students (200 boys and 200 girls were selected by multistage cluster sampling method and answered the bullying prevalence questionnaire and subjective well-being inventory (divergent validity. For data analysis, factor analysis method, Cronbach's alpha coefficient and Pearson’s correlation test were used by SPSS software version 22 and AMOS version 21. Results: factor analysis result showed that this questionnaire was saturated with three factors and had good fitness scales. Significant negative relationships of bullying prevalence with subjective well-being (r = -0.10 and P ≤ 0.05 and academic achievement (r = -0.18 and P ≤ 0.01 were obtained. Cronbach's alpha for the total scale was calculated as 0.81, and for each of the subscales it was as follows: bullying: 0.81, victim 0.75, and pro-social 0.70; all the scores were satisfactory. Conclusions: Findings of the research showed that the Persian version of the bullying prevalence questionnaire was acceptable among students concerning psychometric characteristic and it can be used as a valid instrument for psychological studies.

  18. Diagenesis does not invent anything new: Precise replication of conodont structures by secondary apatite.

    Science.gov (United States)

    Ferretti, Annalisa; Malferrari, Daniele; Medici, Luca; Savioli, Martina

    2017-05-09

    Conodont elements are important archives of sea/pore water chemistry yet they often exhibit evidence of diagenetic mineral overgrowth which may be biasing measurents. We decided to investigate this phenomenon by characterising chemically and crystallographically, the original biomineral tissue and the diagenetic mineral nature of conodont elements from the Ordovician of Normandy. Diagenetic apatite crystals observed on the surface of conodont elements show distinctive large columnar, blocky or web-like microtextures. We demonstrate that these apatite neo-crystals exhibit the same chemical composition as the original fossil structure. X-ray microdiffraction has been applied herein for the first time to conodont structural investigation. Analyses of the entire conodont element surface of a variety of species have revealed the existence of a clear pattern of crystal preferred orientation. No significant difference in unit cell parameters was documented between the newly formed apatite crystals and those of the smooth conodont surfaces, thus it emerges from our research that diagenesis has strictly replicated the unit cell signature of the older crystals.

  19. Effect of principal and secondary ligands on the electronic structures and spectra of a series of ruthenium(II complexes

    Directory of Open Access Journals (Sweden)

    Zhang Yanli

    2016-01-01

    Full Text Available A DFT(density functional theory/TDDFT(time-dependent density functional theory investigation is performed to study the ground-state geometries, electronic structures, and absorption spectra of twelve ruthenium(II thiosemicarbazone complexes [Ru(CO(C(Ln], where Ln=derivatives of dibasic tetradentate Schiff-base ligand and X=AsPh3/PPh3/Py. The ground-state geometries are optimized at the B3LYP/6-31G(d-LANL2DZ level, and the spectra are simulated by means of TD-B3LYP/6-31G(d-LANL2DZ method on the basis of the optimized geometries. The influence of principal and secondary ligands (Ln and X on transition characters and absorption peak positions is evaluated.

  20. A test of AMBER force fields in predicting the secondary structure of α-helical and β-hairpin peptides

    Science.gov (United States)

    Gao, Ya; Zhang, Chaomin; Wang, Xianwei; Zhu, Tong

    2017-07-01

    We tested the ability of some current AMBER force fields, namely, AMBER03, AMBER99SB, AMBER99SB-ildn, AMBER99SB-nmr, AMBER12SB, AMBER14SB, and AMBER14ipq, with implicit solvent model in reproducing the folding behavior of two peptides by REMD simulations. AMBER99SB-nmr force field provides the most reliable performance. After a novel polarized hydrogen bond charge model is considered, the α-helix successfully folded to its native state, while the further folding of the β-hairpin is not observed. This study strongly suggests that polarization effect and correct torsional term are important to investigate dynamic and conformational properties of peptides with different secondary structures.

  1. Secondary structure of gp160 and gp120 envelope glycoproteins of human immunodeficiency virus type 1: a Fourier transform infrared spectroscopic study.

    Science.gov (United States)

    Decroly, E; Cornet, B; Martin, I; Ruysschaert, J M; Vandenbranden, M

    1993-06-01

    The secondary structure of the precursor (gp160) of the envelope protein of human immunodeficiency virus type 1 (BH10) and its receptor-binding subunit (gp120) was studied by Fourier-transformed attenuated total reflection spectroscopy. A higher alpha-helix/beta-sheet ratio in the gp120 subunit than in the precursor indicates a structural heterogeneity between the two subunits (gp120 and gp41), in agreement with classical secondary-structure predictions. The secondary structure of gp41 was estimated and compared with existing models. The high alpha-helical content in gp41 and the dominant beta-sheet content in gp120 resemble the distribution in influenza virus hemagglutinin subunits.

  2. Dopamine agonist suppression of rapid-eye-movement sleep is secondary to sleep suppression mediated via limbic structures

    Energy Technology Data Exchange (ETDEWEB)

    Miletich, R.S.

    1985-01-01

    The effects of pergolide, a direct dopamine receptor agonist, on sleep and wakefulness, motor behavior and /sup 3/H-spiperone specific binding in limbic structures and striatum in rats was studied. The results show that pergolide induced a biphasic dose effect, with high doses increasing wakefulness and suppressing sleep while low dose decreased wakefulness, but increased sleep. It was shown that pergolide-induced sleep suppression was blocked by ..cap alpha..-glupenthixol and pimozide, two dopamine receptor antagonists. It was further shown that pergolide merely delayed the rebound resulting from rapid-eye-movement (REM) sleep deprivation, that dopamine receptors stimulation had no direct effect on the period, phase or amplitude of the circadian rhythm of REM sleep propensity and that there was no alteration in the coupling of REM sleep episodes with S/sub 2/ episodes. Rapid-eye-movement sleep deprivation resulted in increased sensitivity to the pergolide-induced wakefulness stimulation and sleep suppression and pergolide-induced motor behaviors of locomotion and head bobbing. /sup 3/H-spiperone specific binding to dopamine receptors was shown to be altered by REM sleep deprivation in the subcortical limbic structures. It is concluded that the REM sleep suppressing action of dopamine receptor stimulation is secondary to sleep suppression per se and not secondary to a unique effect on the REM sleep. Further, it is suggested that the wakefulness stimulating action of dopamine receptor agonists is mediated by activation of the dopamine receptors in the terminal areas of the mesolimbocortical dopamine projection system.

  3. Variability in secondary structure of 18S ribosomal RNA as topological marker for identification of Paramecium species.

    Science.gov (United States)

    Shakoori, Farah R; Tasneem, Fareeda; Al-Ghanim, K; Mahboob, S; Al-Misned, F; Jahan, Nusrat; Shakoori, Abdul Rauf

    2014-12-01

    Besides cytological and molecular applications, Paramecium is being used in water quality assessment and for determination of saprobic levels. An unambiguous identification of these unicellular eukaryotes is not only essential, but its ecological diversity must also be explored in the local environment. 18SrRNA genes of all the strains of Paramecium species isolated from waste water were amplified, cloned and sequenced. Phylogenetic comparison of the nucleotide sequences of these strains with 23 closely related Paramecium species from GenBank Database enabled identification of Paramecium multimicronucleatum and Paramecium jenningsi. Some isolates did not show significant close association with other Paramecium species, and because of their unique position in the phylogenetic tree, they were considered new to the field. In the present report, these isolates are being designated as Paramecium caudatum pakistanicus. In this article, secondary structure of 18SrRNA has also been analyzed as an additional and perhaps more reliable topological marker for species discrimination and for determining possible phylogenetic relationship between the ciliate species. On the basis of comparison of secondary structure of 18SrRNA of various isolated Paramacium strains, and among Paramecium caudatum pakistanicus, Tetrahymena thermophila, Drosophila melanogaster, and Homo sapiens, it can be deduced that variable regions are more helpful in differentiating the species at interspecific level rather than at intraspecific level. It was concluded that V3 was the least variable region in all the organisms, V2 and V7 were the longest expansion segments of D. melanogaster and there was continuous mutational bias towards G.C base pairing in H. sapiens. © 2014 Wiley Periodicals, Inc.

  4. [Spectroscopic study on the effect of crystallization of the hydroxyapatite on the secondary structure of bovine serum albumin].

    Science.gov (United States)

    Ye, Feng; An, Ying-ge; Qin, De-zhi; Yang, Lin; She, Lan; Xing, Rui-min

    2007-02-01

    The effect of crystallization of hydroxyapatite on the secondary structure of bovine serum albumin (BSA) was studied by circular dichroism spectrum, Fourier transform infrared spectroscopy, derivative, deconvolution and curve-fitting techniques in the present paper. The CD results show that pure bovine serum albumin is composed of 56.8% alpha-helices, 5.8% beta-sheets, 14.1% beta-turns and 23.9% random structures, while the bovine serum albumin in the Ca10(PO4)6(OH)2/bovine serum albumin solution is composed of 25.4% alpha-helices, 25.0% beta-sheets, 20.0% beta-turns and 29.7% random structures. The results of Fourier transform infrared spectroscopy are in good agreement with those from the CD spectra. From these results it can be seen that the percentage of alpha-helix decreased, while that of the beta-sheet increased with the formation of the crystal of hydroxyapatite, and with the reaction time increasing, the percentages of alpha-helix obviously dropped and those of beta-sheet markedly rose. These results showed that alpha-helix transformed into beta-sheet. Furthermore the essence of these changes is discussed.

  5. Secondary structure of double-stranded DNA under stretching: Elucidation of the stretched form

    Science.gov (United States)

    Maaloum, M.; Beker, A.-F.; Muller, P.

    2011-03-01

    Almost two decades ago, measurements of force versus extension on isolated double-stranded DNA molecules revealed a force plateau. This unusual stretching phenomenon in DNA suggests that the long molecules may be extended from the usual B form into a new conformation. Different models have been proposed to describe the nature of DNA in its stretched form, S-DNA. Using atomic force microscopy combined with a molecular combing method, we identified the structure of λ-phage DNA for different stretching values. We provide strong evidence for the existence of a first-order transition between B form and S form. Beyond a certain extension of the natural length, DNA molecules adopt a new double-helix conformation characterized by a diameter of 1.2 nm and a helical pitch of 18 nm.

  6. Teaching Through Interactions in Secondary School Classrooms: Revisiting the Factor Structure and Practical Application of the Classroom Assessment Scoring System–Secondary

    OpenAIRE

    Hafen, Christopher A.; Hamre, Bridget K.; Allen, Joseph P.; Bell, Courtney A.; Gitomer, Drew H.; Pianta, Robert C.

    2014-01-01

    Valid measurement of how students’ experiences in secondary school classrooms lead to gains in learning requires a developmental approach to conceptualizing classroom processes. This article presents a potentially useful theoretical model, the Teaching Through Interactions framework, which posits teacher-student interactions as a central driver for student learning and that teacher-student interactions can be organized into three major domains. Results from 1,482 classrooms provide evidence f...

  7. A novel Multi-Agent Ada-Boost algorithm for predicting protein structural class with the information of protein secondary structure.

    Science.gov (United States)

    Fan, Ming; Zheng, Bin; Li, Lihua

    2015-10-01

    Knowledge of the structural class of a given protein is important for understanding its folding patterns. Although a lot of efforts have been made, it still remains a challenging problem for prediction of protein structural class solely from protein sequences. The feature extraction and classification of proteins are the main problems in prediction. In this research, we extended our earlier work regarding these two aspects. In protein feature extraction, we proposed a scheme by calculating the word frequency and word position from sequences of amino acid, reduced amino acid, and secondary structure. For an accurate classification of the structural class of protein, we developed a novel Multi-Agent Ada-Boost (MA-Ada) method by integrating the features of Multi-Agent system into Ada-Boost algorithm. Extensive experiments were taken to test and compare the proposed method using four benchmark datasets in low homology. The results showed classification accuracies of 88.5%, 96.0%, 88.4%, and 85.5%, respectively, which are much better compared with the existing methods. The source code and dataset are available on request.

  8. Isolation and Structure Elucidation of Uncommon Secondary Metabolites from Cistus salviifolius L.

    Directory of Open Access Journals (Sweden)

    Perihan Gürbüz

    2015-01-01

    Full Text Available To our knowledge this is the first report on the isolation of a flavonoid glycoside: quercetin 3-O-α-arabinopyranoside (5, two phenylbutanon glycosides: 4-(4'-O-[6''-O-galloyl-β-galactopyranosyl]-3'-hydroxyphenyl-butan-2-on (8, 4-(3'-O-β-glucopyranosyl-4'-hydroxyphenyl-butan-2-on (9, one phloroglucinol glycoside: 1-O-β-glucopyranosyl-3,5-dimethoxybenzene (10 and a steroid glycoside: sitosterol-3-O-(6''-O-butanoyl-β-galactopyranoside (14 from the Cistus species (Cistaceae. Additional to these compounds three flavonol aglycones: kaempferol (1, quercetin (2, myricetin (3; three flavonoid glycosides; kaempferol 3-O-β-(6''-O-trans-p-coumaroyl-glucopyranoside (4, quercetin 3-O-β-galactopyranoside (6, myricetin 3-O-β-galactopyranoside (7; one phloroglucinol glycoside: 1-O-β-glucopyranosyl-3,5-dimethoxybenzene (11; one steroid aglycone: β-sitosterol (12; one steroid glycoside: Sitosterol-3-O- β-glucopyranoside (13 were isolated from the aerial parts of the Cistus salviifolius L.. Their structures were identified using spectral methods (UV, IR, 1D- and 2D-NMR, and ESI-MS.

  9. Aliphatic Claisen rearrangement transition state structure from secondary. cap alpha. -deuterium isotope effects

    Energy Technology Data Exchange (ETDEWEB)

    Gajewski, J.J.; Conrad, N.D.

    1979-05-09

    The kinetics isotope effects (KIE) at C/sub 4/ and C/sub 6/ in the 3,3 shift of 3-oxa-1,5-hexadiene appear to reveal that the transition state comes early, and that it involves much more bond breaking than making in contrast to the carbon 3,3 shift of relatively unperturbed dienes. At 160/sup 0/C the normal KIE at C/sub 4/ is 1.092 and the inverse KIE at C/sub 6/ is 1.025. The ratio of the KIE to the equilibrium isotope effect at the bond breaking site is (0.09/1.27) or 1/3, while that of the bond making site is only (1.025/1.16) or < 1/6. These results seem to confirm that the transition state is early because of the exothermicity of the reaction. The transition state structure suggests that radical stabilizing substituents on C/sub 1/, C/sub 4/, and C/sub 6/ will stabilize the transition state to a greater extent than placement of the same substituents on C/sub 2/ and C/sub 5/.

  10. Secondary deuterium isotope effects and transition state structure in the aromatic claisen rearrangement

    Energy Technology Data Exchange (ETDEWEB)

    McMichael, K.D.; Korver, G.L.

    1979-05-09

    Kinetic experiments were carried out simultaneously on separate methyl salicylate solutions of allyl phenyl ether and its deuterated phenyl analogues at 170 to 195/sup 0/C. Gas chromatographic analysis for allyl phenyl ether using an internal standard (anisole) and mechanical integration produced concentration/time data which were fitted to the exponential form of the first-order rate equation by a standard and nonlinear least-square program. At least 15 points were obtained for each run, covering 10 to 85% reaction. The derived isotope effects show no temperature dependence. Averages for 6 runs with each compound are k/sub H//k/sub ..cap alpha..-D/sub 2// = 1.18 and K/sub H//k/sub ..gamma..-D/sub 2// = 0.95. An equilibrium ..cap alpha.. effect of 1.30 and a ..gamma.. effect of 0.87 may be calculated for both deuterium atoms at 185/sup 0/C. These results show that the C--H vibration frequencies are approximately (1.18 - 1)/(1.27 - 1) or 57 to 77% of the way from those of allyl phenyl ether to those of the cyclohexadiene intermediate. The C--H frequencies of the ..gamma.. carbon in the transition state are about (0.95 - 1)/(0.88 - 1) or 22 to 62% of the way to those of the intermediate. The structure of the transition state, as far as these bonding frequencies are concerned, is consistent with the Claisen rearrangement.

  11. Identification and classification of conserved RNA secondary structures in the human genome.

    Directory of Open Access Journals (Sweden)

    Jakob Skou Pedersen

    2006-04-01

    Full Text Available The discoveries of microRNAs and riboswitches, among others, have shown functional RNAs to be biologically more important and genomically more prevalent than previously anticipated. We have developed a general comparative genomics method based on phylogenetic stochastic context-free grammars for identifying functional RNAs encoded in the human genome and used it to survey an eight-way genome-wide alignment of the human, chimpanzee, mouse, rat, dog, chicken, zebra-fish, and puffer-fish genomes for deeply conserved functional RNAs. At a loose threshold for acceptance, this search resulted in a set of 48,479 candidate RNA structures. This screen finds a large number of known functional RNAs, including 195 miRNAs, 62 histone 3'UTR stem loops, and various types of known genetic recoding elements. Among the highest-scoring new predictions are 169 new miRNA candidates, as well as new candidate selenocysteine insertion sites, RNA editing hairpins, RNAs involved in transcript auto regulation, and many folds that form singletons or small functional RNA families of completely unknown function. While the rate of false positives in the overall set is difficult to estimate and is likely to be substantial, the results nevertheless provide evidence for many new human functional RNAs and present specific predictions to facilitate their further characterization.

  12. Bilateral thalamic infarction that is secondary thrombosis to the deep venous structures: report of two cases

    Directory of Open Access Journals (Sweden)

    Serdar Oruc

    2016-12-01

    Full Text Available Deep cerebral venous thrombosis cases are the %6 of the cerebral venous thrombosis (CVT cases. The recognition of these patients is difficult since this disease is rarely observed and its clinical presentation is nonspecific and variable. In its etiology, the most frequently observed reasons are hypercoagulopathy, oral contraceptive use, pregnancy, puerperium, dehydration, and head trauma. Less frequently observed reasons are vasculitis, inflammatory bowel disease, malignancies, anemia, and tumor invasion through venous sinuses. In this report, were presented two cases who were admitted to the hospital with headache complaint and cognitive changes.According to the advanced magnetic resonance imaging, acute infarction was detected in bilateral thalamus. We observed CVT with adversely affected deep cerebral venous system structures. CVT development was associated with the use of oral contraceptives in the first case and it was associated with anemia in the second case. Both patients were discharged from the hospital upon healing with anticoagulant therapy. In this study, it has been emphasized by representing these two patients that CVT should be thought in the etiology of bilateral thalamic ischemia. Furthermore, it is also crucial to known that these patients can be fully improved clinically and radiologically in case appropriate medical treatment is applied.

  13. The Role of the Local Conformation of a Cyclically Constrained β-AMINO Acid in the Secondary Structures of a Mixed α/β Diastereomer Pair

    Science.gov (United States)

    Blodgett, Karl N.; Zwier, Timothy S.

    2017-06-01

    Synthetic foldamers are non-natural polymers designed to fold into unique secondary structures that either mimic nature's preferred secondary structures, or expand their possibilities. Among the most studied synthetic foldamers are β-peptides, which lengthen the distance between amide groups from the single substituted carbon spacer in α-peptides by one (β) additional carbon. Cyclically constrained β-amino acids can impart rigidity to the secondary structure of oligomers by locking in a particular conformation. The β-residue cis-2-aminocyclohexanecarboxylic acid (cis-ACHC) is one such amino acid which has been shown to drive vastly different secondary structures as a function of the local conformation of the cyclohexane ring. We present data on two diastereomers of the mixed α/β tri-peptide Ac-Ala-β_{ACHC}-Ala-NHBn which differ from one another by the chirality along the ACHC residue (SRSS vs. SSRS). The first oligomer is known to crystallize to a 9/11 mixed helix while the second forms no intramolecular hydrogen bonds in the crystal state. This talk will describe the conformation-specific IR and UV spectroscopy of the above two diastereomers under jet cooled conditions in the gas phase. Assignments based on comparison with calculations show the presence of incipient 9/11 mixed helices and competing structures containing more tightly folded hydrogen-bonded networks. The calculated global minimum structures are observed in each case, and in each case these folded structures are reminiscent of a β-turn.

  14. Changing Socio-Economic Structures and the Challenge of Secondary Schooling: Voices from a Village in Odisha

    Science.gov (United States)

    Chakraborty, Suchita

    2016-01-01

    Secondary education has been a relatively neglected area in India, both at the level of policy and research. Statistical data at the secondary level of education reveals a bleak picture in terms of enrolment and completion rates. This article explores the underlying reasons for the dismal scenario at the secondary level of education by situating…

  15. Different epigenetic layers engage in complex crosstalk to define the epigenetic state of mammalian rRNA genes.

    Science.gov (United States)

    Grummt, Ingrid

    2007-04-15

    Eukaryotic cells contain several hundred ribosomal RNA (rRNA) genes (rDNA), a fraction of them being silenced by epigenetic mechanisms. The presence of two epigenetically distinct states of rRNA genes provides a unique opportunity to decipher the molecular mechanisms that establish the euchromatic, i.e. transcriptionally active, and the heterochromatic, i.e. transcriptionally silent, state of rDNA. This article summarizes our knowledge of the epigenetic mechanisms that control rDNA transcription and emphasizes how DNA methyltransferases and histone-modifying enzymes work in concert with chromatin-remodeling complexes and RNA-guided mechanisms to establish a specific chromatin structure that defines the transcriptional state of rRNA genes. These studies exemplify the mutual dependence and complex crosstalk among different epigenetic players in the alteration of the chromatin structure during the process of gene activation or silencing.

  16. Evidence of birth-and-death evolution of 5S rRNA gene in Channa species (Teleostei, Perciformes).

    Science.gov (United States)

    Barman, Anindya Sundar; Singh, Mamta; Singh, Rajeev Kumar; Lal, Kuldeep Kumar

    2016-12-01

    In higher eukaryotes, minor rDNA family codes for 5S rRNA that is arranged in tandem arrays and comprises of a highly conserved 120 bp long coding sequence with a variable non-transcribed spacer (NTS). Initially the 5S rDNA repeats are considered to be evolved by the process of concerted evolution. But some recent reports, including teleost fishes suggested that evolution of 5S rDNA repeat does not fit into the concerted evolution model and evolution of 5S rDNA family may be explained by a birth-and-death evolution model. In order to study the mode of evolution of 5S rDNA repeats in Perciformes fish species, nucleotide sequence and molecular organization of five species of genus Channa were analyzed in the present study. Molecular analyses revealed several variants of 5S rDNA repeats (four types of NTS) and networks created by a neighbor net algorithm for each type of sequences (I, II, III and IV) did not show a clear clustering in species specific manner. The stable secondary structure is predicted and upstream and downstream conserved regulatory elements were characterized. Sequence analyses also shown the presence of two putative pseudogenes in Channa marulius. Present study supported that 5S rDNA repeats in genus Channa were evolved under the process of birth-and-death.

  17. Effect of Resonant Magnetic Perturbations on secondary structures in Drift-Wave turbulence

    Science.gov (United States)

    Leconte, Michael

    2011-10-01

    In this work, we study the effects of RMPs on turbulence, flows and confinement, in the framework of two paradigmatic models, resistive ballooning and resistive drift waves. For resistive ballooning turbulence, we use 3D global numerical simulations, including RMP fields and (externally-imposed) sheared rotation profile. Without RMPs, relaxation oscillations of the pressure profile occur. With RMPs, results show that long-lived convection cells are generated by the combined effects of pressure modulation and toroidal curvature coupling. These modify the global structure of the turbulence and eliminate relaxation oscillations. This effect is due mainly to a modification of the pressure profile linked to the presence of residual magnetic island chains. Hence convection-cell generation increases for increasing δBr/B0. For RMP effect on zonal flows in drift wave turbulence, we extend the Hasegawa-Wakatani model to include RMP fields. The effect of the RMPs is to induce a linear coupling between the zonal electric field and the zonal density gradient, which drives the system to a state of electron radial force balance for large δBr/B0. Both the vorticity flux (Reynolds stress), and particle flux are modulated. We derive an extended predator prey model which couples zonal potential and density dynamics to the evolution of turbulence intensity. This model has both turbulence drive and RMP amplitude as control parameters, and predicts a novel type of transport bifurcation in the presence of RMPs. We find a novel set of system states that are similar to the Hmode-like state of the standard predator-prey model, but for which the power threshold is now a function of the RMP strength. For small RMP amplitude and low collisionality, both the ambient turbulence and zonal flow energy increase with δBr/B0. For larger RMP strength, the turbulence energy increases, but the energy of zonal flows decreases with δBr/B0, corresponding to a damping of zonal flows. At high

  18. STUDY OF THE EFFECT OF MIXED ALKOXIDES OXYPROPYLATED AROMATIC SECONDARY AMINES ON THE STRUCTURE OF DIENE POLYMERS

    Directory of Open Access Journals (Sweden)

    A. V. Firsova

    2014-01-01

    Full Text Available Summary. This article discusses the relationship structure of the diene and styrene-butadiene copolymers (SBR, the structure of the part of the initiating system of n-butyl lithium + modifier, which is a mixed alkoxide of an alkali and alkaline earth metals, which allows to control the microstructure of the diene polymer and its molecular weight characteristics. Alcohol derivatives selected high-boiling alcohols tetra (hydroxypropyl ethylenediamine (lapromol - 294 and tetrahydrofurfuryl alcohol (TGFS. The scheme of obtaining styrene-butadiene random copolymers (SBR with a high content (64 ± 4 % of vinyl units was developed. The process of copolymerization with sodium-calcium-lithium complex Са(С4Н9 2 • С4Н9Na • LiOR was carried out. After water decontamination residues deactivated complex remain in the polymer as a filler. Studied the copolymerization of butadiene with styrene in the presence of lithium amide, which is obtained on the basis of the alcohols containing the group - NH -. With the increasing solubility of the branching alkoxides increases in hydrocarbon solvents. Found that sodium alkoxide hydroxypropyl aniline decane insoluble, the sodium alcoholate hydroxypropyl toluidine soluble in decane. The results of studies of the effect of mixed alkoxides oxypropylated aromatic secondary amines on the structure of diene polymers. The Providing the necessary initiation systems for preparing functionalized polymers. It was revealed that secondary amines from which the lithium amides are inactive, so the polymerization of monomers was carried out in the presence of electron as that used glycol ethers - diglyme, THF, 2,2 - ditetragidrofurfuril propane, which increase polymer-filler interaction. The results of research of the microstructure of the diene part of SBR obtained in the mixed alkali metal alkoxide with a mixture of lapromol alcohols, toluidine and TGFS showed that increasing toluidine consisting of mixed modifier reduces

  19. Protein secondary structure of Green Lynx spider dragline silk investigated by solid-state NMR and X-ray diffraction.

    Science.gov (United States)

    Xu, Dian; Shi, Xiangyan; Thompson, Forrest; Weber, Warner S; Mou, Qiushi; Yarger, Jeffery L

    2015-11-01

    In this study, the secondary structure of the major ampullate silk from Peucetia viridans (Green Lynx) spiders is characterized by X-ray diffraction and solid-state NMR spectroscopy. From X-ray diffraction measurement, β-sheet nanocrystallites were observed and found to be highly oriented along the fiber axis, with an orientational order, fc≈0.98. The size of the nanocrystallites was determined to be on average 2.5nm×3.3nm×3.8nm. Besides a prominent nanocrystalline region, a partially oriented amorphous region was also observed with an fa≈0.89. Two-dimensional (13)C-(13)C through-space and through-bond solid-state NMR experiments were employed to elucidate structure details of P. viridans silk proteins. It reveals that β-sheet nanocrystallites constitutes 40.0±1.2% of the protein and are dominated by alanine-rich repetitive motifs. Furthermore, based upon the NMR data, 18±1% of alanine, 60±2% glycine and 54±2% serine are incorporated into helical conformations. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Imposing function down a (cupin)-barrel: secondary structure and metal stereochemistry in the αKG-dependent oxygenases.

    Science.gov (United States)

    Hangasky, John A; Taabazuing, Cornelius Y; Valliere, Meaghan A; Knapp, Michael J

    2013-04-01

    The Fe(ii)/αketoglutarate (αKG) dependent oxygenases catalyze a diverse range of reactions significant in biological processes such as antibiotic biosynthesis, lipid metabolism, oxygen sensing, and DNA and RNA repair. Although functionally diverse, the eight-stranded β-barrel (cupin) and HX(D/E)XnH facial triad motifs are conserved in this super-family of enzymes. Crystal structure analysis of 25 αKG oxygenases reveals two stereoisomers of the Fe cofactor, Anti and Clock, which differ in the relative position of the exchangeable ligand position and the primary substrate. Herein, we discuss the relationship between the chemical mechanism and the secondary coordination sphere of the αKG oxygenases, within the constraints of the stereochemistry of the Fe cofactor. Sequence analysis of the cupin barrel indicates that a small subset of positions constitute the second coordination sphere, which has significant ramifications for the structure of the ferryl intermediate. The competence of both Anti and Clock stereoisomers of Fe points to a ferryl intermediate that is 5 coordinate. The small number of conserved close contacts within the active sites of αKG oxygenases can be extended to chemically related enzymes, such as the αKG-dependent halogenases SyrB2 and CytC3, and the non-αKG dependent dioxygenases isopenicillin N synthase (IPNS) and cysteine dioxygenase (CDO).

  1. Immunogenic Domains and Secondary Structure of Escherichia coli Recombinant Secreted Protein Escherichia coli-Secreted Protein B.

    Science.gov (United States)

    Caetano, Bruna Alves; Rocha, Letícia Barboza; Carvalho, Eneas; Piazza, Roxane Maria Fontes; Luz, Daniela

    2017-01-01

    Several pathogenic bacteria are able to induce the attaching and effacing (A/E) lesion. The A/E lesion is caused by effector proteins, such as Escherichia coli-secreted protein B (EspB), responsible together with Escherichia coli-secreted protein D for forming a pore structure on the host cell, which allows the translocation of effector proteins. Different variants of this protein can be found in E. coli strains, and during natural infection or when this protein is injected, this leads to variant-specific production of antibodies, which may not be able to recognize other variants of this bacterial protein. Herein, we describe the production of a hybrid recombinant EspB toxin that comprises all known variants of this protein. This recombinant protein could be useful as an antigen for the production of antibodies with broad-range detection of EspB-bearing bacteria, or as an antigen that could be used in vaccine formulation to generate antibodies against different EspB variants, thereby increasing immunization potential. In addition, the recombinant protein allowed us to analyze its secondary structure, to propose the immunogenic regions of EspB variants, and also to characterize anti-EspB antibodies. Our results suggest that this hybrid protein or a protein composed of the conserved immunogenic regions could be used for a variety of clinical applications.

  2. Immunogenic Domains and Secondary Structure of Escherichia coli Recombinant Secreted Protein Escherichia coli-Secreted Protein B

    Science.gov (United States)

    Caetano, Bruna Alves; Rocha, Letícia Barboza; Carvalho, Eneas; Piazza, Roxane Maria Fontes; Luz, Daniela

    2017-01-01

    Several pathogenic bacteria are able to induce the attaching and effacing (A/E) lesion. The A/E lesion is caused by effector proteins, such as Escherichia coli-secreted protein B (EspB), responsible together with Escherichia coli-secreted protein D for forming a pore structure on the host cell, which allows the translocation of effector proteins. Different variants of this protein can be found in E. coli strains, and during natural infection or when this protein is injected, this leads to variant-specific production of antibodies, which may not be able to recognize other variants of this bacterial protein. Herein, we describe the production of a hybrid recombinant EspB toxin that comprises all known variants of this protein. This recombinant protein could be useful as an antigen for the production of antibodies with broad-range detection of EspB-bearing bacteria, or as an antigen that could be used in vaccine formulation to generate antibodies against different EspB variants, thereby increasing immunization potential. In addition, the recombinant protein allowed us to analyze its secondary structure, to propose the immunogenic regions of EspB variants, and also to characterize anti-EspB antibodies. Our results suggest that this hybrid protein or a protein composed of the conserved immunogenic regions could be used for a variety of clinical applications. PMID:28484467

  3. Immunogenic Domains and Secondary Structure of Escherichia coli Recombinant Secreted Protein Escherichia coli-Secreted Protein B

    Directory of Open Access Journals (Sweden)

    Roxane Maria Fontes Piazza

    2017-04-01

    Full Text Available Several pathogenic bacteria are able to induce the attaching and effacing (A/E lesion. The A/E lesion is caused by effector proteins, such as Escherichia coli-secreted protein B (EspB, responsible together with Escherichia coli-secreted protein D for forming a pore structure on the host cell, which allows the translocation of effector proteins. Different variants of this protein can be found in E. coli strains, and during natural infection or when this protein is injected, this leads to variant-specific production of antibodies, which may not be able to recognize other variants of this bacterial protein. Herein, we describe the production of a hybrid recombinant EspB toxin that comprises all known variants of this protein. This recombinant protein could be useful as an antigen for the production of antibodies with broad-range detection of EspB-bearing bacteria, or as an antigen that could be used in vaccine formulation to generate antibodies against different EspB variants, thereby increasing immunization potential. In addition, the recombinant protein allowed us to analyze its secondary structure, to propose the immunogenic regions of EspB variants, and also to characterize anti-EspB antibodies. Our results suggest that this hybrid protein or a protein composed of the conserved immunogenic regions could be used for a variety of clinical applications.

  4. Osmolality and non-structural carbohydrate composition in the secondary phloem of trees across a latitudinal gradient in Europe

    Directory of Open Access Journals (Sweden)

    Anna eLintunen

    2016-06-01

    Full Text Available Phloem osmolality and its components are involved in basic cell metabolism, cell growth, and in various physiological processes including the ability of living cells to withstand drought and frost. Osmolality and sugar composition responses to environmental stresses have been extensively studied for leaves, but less for the secondary phloem of plant stems and branches. Leaf osmotic concentration and the share of pinitol and raffinose among soluble sugars increase with increasing drought or cold stress, and osmotic concentration is adjusted with osmoregulation. We hypothesize that similar responses occur in the secondary phloem of branches. We collected living bark samples from branches of adult Pinus sylvestris, Picea abies, Betula pendula and Populus tremula trees across Europe, from boreal Northern Finland to Mediterranean Portugal. In all studied species, the observed variation in phloem osmolality was mainly driven by variation in phloem water content, while tissue solute content was rather constant across regions. Osmoregulation, in which osmolality is controlled by variable tissue solute content, was stronger for Betula and Populus in comparison to the evergreen conifers. Osmolality was lowest in mid-latitude region, and from there increased by 37% towards northern Europe and 38% towards southern Europe due to low phloem water content in these regions. The ratio of raffinose to all soluble sugars was negligible at mid-latitudes and increased towards north and south, reflecting its role in cold and drought tolerance. For pinitol, another sugar known for contributing to stress tolerance, no such latitudinal pattern was observed. The proportion of sucrose was remarkably low and that of hexoses (i.e. glucose and fructose high at mid-latitudes. The ratio of starch to all non-structural carbohydrates increased towards the northern latitudes in agreement with the build-up of osmotically inactive C reservoir that can be converted into soluble

  5. Infrared and circular dichroism spectroscopic characterisation of secondary structure components of a water treatment coagulant protein extracted from Moringa oleifera seeds.

    Science.gov (United States)

    Kwaambwa, H M; Maikokera, R

    2008-06-15

    The secondary structure of a water treatment coagulant protein extracted from Moringa oleifera (MO) seeds has been investigated by Fourier transform infrared spectroscopy (FTIR) in the dried state, and by circular dichroism (CD) spectroscopy. The FTIR and CD spectra indicate that the secondary structure of the protein is dominated by alpha-helix. The FTIR spectrum recorded two distinct and strong absorption bands at 1656 cm(-1) and 1542 cm(-1), in the usual range of absorption of helices of proteins. The CD spectrum showed the shape of mainly alpha-helical secondary structure (estimated to be 58+/-4%) characteristic of negative ellipticity bands near 222 nm and 208 nm and a positive band at 192 nm. The beta-sheet structure composition was estimated to be 10+/-3% whereas unordered structures were around 33%. Changes in solution pH affected the protein secondary structure significantly only at pH values above 10, as indicated by CD spectra, whereas ionic strength had minimal effect. CD data also showed that sodium dodecyl sulphate (SDS) interacts with the coagulant protein and modifies the protein conformation. The surfactant-induced conformational change of the coagulant protein was confirmed by quenching of tryptophan fluorescence of the protein.

  6. A renaissance for the pioneering 16S rRNA gene

    Energy Technology Data Exchange (ETDEWEB)

    Tringe, Susannah; Hugenholtz, Philip

    2008-09-07

    Culture-independent molecular surveys using the 16S rRNA gene have become a mainstay for characterizing microbial community structure over the last quarter century. More recently this approach has been overshadowed by metagenomics, which provides a global overview of a community's functional potential rather than just an inventory of its inhabitants. However, the pioneering 16S rRNA gene is making a comeback in its own right thanks to a number of methodological advancements including higher resolution (more sequences), analysis of multiple related samples (e.g. spatial and temporal series) and improved metadata and use of metadata. The standard conclusion that microbial ecosystems are remarkably complex and diverse is now being replaced by detailed insights into microbial ecology and evolution based only on this one historically important marker gene.

  7. Analysis of the factor structure of the Sociocultural Attitudes Towards Appearance Questionnaire (SATAQ-3) in Spanish secondary-school students through exploratory structural equation modeling.

    Science.gov (United States)

    Sánchez-Carracedo, David; Barrada, Juan Ramón; López-Guimerà, Gemma; Fauquet, Jordi; Almenara, Carlos A; Trepat, Esther

    2012-01-01

    The aims of the present study were: (1) to assess the factor structure of the SATAQ-3 in Spanish secondary-school students by means of exploratory factor analysis (EFA), confirmatory factor analysis (CFA) and exploratory structural equation modeling (ESEM) models; and (2) to study its invariance by sex and school grade. ESEM is a technique that has been proposed for the analysis of internal structure that overcomes some of the limitations of EFA and CFA. Participants were 1559 boys and girls in grades seventh to tenth. The results support the four-factor solution of the original version, and reveal that the best fit was obtained with ESEM, excluding Item 20 and with correlated uniqueness between reverse-keyed items. Our version shows invariance by sex and grade. The differences between scores of different groups are in the expected direction, and support the validity of the questionnaire. We recommend a version excluding Item 20 and without reverse-keyed items. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Molecular dynamics-based analyses of the structural instability and secondary structure of the fibrinogen gamma chain protein with the D356V mutation.

    Science.gov (United States)

    Ali, Shabana Kouser; Sneha, P; Priyadharshini Christy, J; Zayed, Hatem; George Priya Doss, C

    2017-09-01

    Mutations in the fibrinogen gamma chain (FGG) gene have been associated with various disorders, such as dysfibrinogenemia, thrombophilia, and hypofibrinogenemia. A literature survey showed that a residue exchange in fibrinogen Milano I from γ Asp to Val at position 330 impairs fibrin polymerization. The D356V (D330V) mutation located in the C-terminus was predicted to be highly deleterious and to affect the function of the protein. The pathogenicity of the altered gene and changes in protein functions were predicted using in silico methods, such as SIFT, PolyPhen 2, I-Mutant 3.0, Align GV-GD, PhD-SNP, and SNPs&GO. The secondary structure of the mutant protein was unwound by the end of the 50-ns simulation period, and a structural change in the helix-turn transition of the alpha-helical (352-356) region residues was observed. Moreover, a change in the length of the helical region was visualized in the mutant trajectory file, indicating the local transient unfolding of the protein. The obtained computational results suggest that the substitution of the neutral amino acid valine for the acidic amino acid aspartic acid at position 356 results in an unwound conformation within 50 ns, which might contribute to defective polymerization. Our analysis also provides insights into the effect of the conformational change in the D356V (D330V) mutant on protein structure and function.

  9. Technologically important extremophile 16S rRNA sequence Shannon entropy and fractal property comparison with long term dormant microbes

    Science.gov (United States)

    Holden, Todd; Gadura, N.; Dehipawala, S.; Cheung, E.; Tuffour, M.; Schneider, P.; Tremberger, G., Jr.; Lieberman, D.; Cheung, T.

    2011-10-01

    Technologically important extremophiles including oil eating microbes, uranium and rocket fuel perchlorate reduction microbes, electron producing microbes and electrode electrons feeding microbes were compared in terms of their 16S rRNA sequences, a standard targeted sequence in comparative phylogeny studies. Microbes that were reported to have survived a prolonged dormant duration were also studied. Examples included the recently discovered microbe that survives after 34,000 years in a salty environment while feeding off organic compounds from other trapped dead microbes. Shannon entropy of the 16S rRNA nucleotide composition and fractal dimension of the nucleotide sequence in terms of its atomic number fluctuation analyses suggest a selected range for these extremophiles as compared to other microbes; consistent with the experience of relatively mild evolutionary pressure. However, most of the microbes that have been reported to survive in prolonged dormant duration carry sequences with fractal dimension between 1.995 and 2.005 (N = 10 out of 13). Similar results are observed for halophiles, red-shifted chlorophyll and radiation resistant microbes. The results suggest that prolonged dormant duration, in analogous to high salty or radiation environment, would select high fractal 16S rRNA sequences. Path analysis in structural equation modeling supports a causal relation between entropy and fractal dimension for the studied 16S rRNA sequences (N = 7). Candidate choices for high fractal 16S rRNA microbes could offer protection for prolonged spaceflights. BioBrick gene network manipulation could include extremophile 16S rRNA sequences in synthetic biology and shed more light on exobiology and future colonization in shielded spaceflights. Whether the high fractal 16S rRNA sequences contain an asteroidlike extra-terrestrial source could be speculative but interesting.

  10. Cationized bovine serum albumin as gene carrier: Influence of specific secondary structure on DNA complexibility and gene transfection.

    Science.gov (United States)

    Du, Jianwei; Li, Bangbang; Zhang, Peng; Wang, Youxiang

    2016-07-01

    In this research, BSA, one of the natural rigid globular proteins with ca. 51% of α-helix secondary structure, was utilized to prepare cationized BSA (cBSA) as gene carrier. Tetraethylenepentamine (TEPA) or polyethylenimine (PEI1800) was grafted to BSA with different grafting levels. Based on the circular dichoism (CD) spectra, all cBSA remained α-helical structure to some degree. This was exciting to endow cBSA with quite different DNA complexibility and cellular biology behavior from the random coiled and flexible polycations such as PEI and poly-l-lysine (PLL). Strangely, the DNA condensability decreased with the increment of TEPA or PEI1800 grafting level. Also, the cBSA could condense DNA effectively to form irregular nanoparticles around 50-200nm above N/P ratio of 10. On account of the excellent hydration of BSA, the cBSA/DNA complexes revealed good colloidal stability under physiological salt condition. Cell culture experiments indicated this BSA-based gene carrier possessed good cellular compatibility. Surprisingly, cBSA/DNA complexes could be uptaken excellently by up to 90% cells. This might be owing to the agitation effect of α-helical structure and the positive potential of these complexes. BSA-PEI1800/DNA complexes with quick endosome escape even had transfection efficiency as high as PEI25k/DNA complexes. Overall, this paper provided us the potential of cBSA as gene carrier and might have some instructions in the design of protein-based gene delivery system. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Uncovering symmetry-breaking vector and reliability order for assigning secondary structures of proteins from atomic NMR chemical shifts in amino acids.

    Science.gov (United States)

    Yu, Wookyung; Lee, Woonghee; Lee, Weontae; Kim, Suhkmann; Chang, Iksoo

    2011-12-01

    Unravelling the complex correlation between chemical shifts of (13) C (α), (13) C (β), (13) C', (1) H (α), (15) N, (1) H ( N ) atoms in amino acids of proteins from NMR experiment and local structural environments of amino acids facilitates the assignment of secondary structures of proteins. This is an important impetus for both determining the three-dimensional structure and understanding the biological function of proteins. The previous empirical correlation scores which relate chemical shifts of (13) C (α), (13) C (β), (13) C', (1) H (α), (15) N, (1) H ( N ) atoms to secondary structures resulted in progresses toward assigning secondary structures of proteins. However, the physical-mathematical framework for these was elusive partly due to both the limited and orthogonal exploration of higher-dimensional chemical shifts of hetero-nucleus and the lack of physical-mathematical understanding underlying those correlation scores. Here we present a simple multi-dimensional hetero-nuclear chemical shift score function (MDHN-CSSF) which captures systematically the salient feature of such complex correlations without any references to a random coil state of proteins. We uncover the symmetry-breaking vector and its reliability order not only for distinguishing different secondary structures of proteins but also for capturing the delicate sensitivity interplayed among chemical shifts of (13) C (α), (13) C (β), (13) C', (1) H (α), (15) N, (1) H ( N ) atoms simultaneously, which then provides a straightforward framework toward assigning secondary structures of proteins. MDHN-CSSF could correctly assign secondary structures of training (validating) proteins with the favourable (comparable) Q3 scores in comparison with those from the previous correlation scores. MDHN-CSSF provides a simple and robust strategy for the systematic assignment of secondary structures of proteins and would facilitate the de novo determination of three-dimensional structures

  12. Correlation of MFOLD-predicted DNA secondary structures with separation patterns obtained by capillary electrophoresis single-strand conformation polymorphism (CE-SSCP) analysis.

    Science.gov (United States)

    Glavac, Damjan; Potocnik, Uros; Podpecnik, Darja; Zizek, Teofil; Smerkolj, Sava; Ravnik-Glavac, Metka

    2002-04-01

    We have studied 57 different mutations within three beta-globin gene promoter fragments with sizes 52 bp, 77 bp, and 193 bp by fluorescent capillary electrophoresis CE-SSCP analysis. For each mutation and wild type, energetically most-favorable predicted secondary structures were calculated for sense and antisense strands using the MFOLD DNA-folding algorithm in order to investigate if any correlation exists between predicted DNA structures and actual CE migration time shifts. The overall CE-SSCP detection rate was 100% for all mutations in three studied DNA fragments. For shorter 52 bp and 77 bp DNA fragments we obtained a positive correlation between the migration time shifts and difference in free energy values of predicted secondary structures at all temperatures. For longer 193 bp beta-globin gene fragments with 46 mutations MFOLD predicted different secondary structures for 89% of mutated strands at 25 degrees C and 40 degrees C. However, the magnitude of the mobility shifts did not necessarily correlate with their secondary structures and free energy values except for the sense strand at 40 degrees C where this correlation was statistically significant (r = 0.312, p = 0.033). Results of this study provided more direct insight into the mechanism of CE-SSCP and showed that MFOLD prediction could be helpful in making decisions about the running temperatures and in prediction of CE-SSCP data patterns, especially for shorter (50-100 bp) DNA fragments. Copyright 2002 Wiley-Liss, Inc.

  13. RNA-TVcurve: a Web server for RNA secondary structure comparison based on a multi-scale similarity of its triple vector curve representation.

    Science.gov (United States)

    Li, Ying; Shi, Xiaohu; Liang, Yanchun; Xie, Juan; Zhang, Yu; Ma, Qin

    2017-01-21

    RNAs have been found to carry diverse functionalities in nature. Inferring the similarity between two given RNAs is a fundamental step to understand and interpret their functional relationship. The majority of functional RNAs show conserved secondary structures, rather than sequence conservation. Those algorithms relying on sequence-based features usually have limitations in their prediction performance. Hence, integrating RNA structure features is very critical for RNA analysis. Existing algorithms mainly fall into two categories: alignment-based and alignment-free. The alignment-free algorithms of RNA comparison usually have lower time complexity than alignment-based algorithms. An alignment-free RNA comparison algorithm was proposed, in which novel numerical representations RNA-TVcurve (triple vector curve representation) of RNA sequence and corresponding secondary structure features are provided. Then a multi-scale similarity score of two given RNAs was designed based on wavelet decomposition of their numerical representation. In support of RNA mutation and phylogenetic analysis, a web server (RNA-TVcurve) was designed based on this alignment-free RNA comparison algorithm. It provides three functional modules: 1) visualization of numerical representation of RNA secondary structure; 2) detection of single-point mutation based on secondary structure; and 3) comparison of pairwise and multiple RNA secondary structures. The inputs of the web server require RNA primary sequences, while corresponding secondary structures are optional. For the primary sequences alone, the web server can compute the secondary structures using free energy minimization algorithm in terms of RNAfold tool from Vienna RNA package. RNA-TVcurve is the first integrated web server, based on an alignment-free method, to deliver a suite of RNA analysis functions, including visualization, mutation analysis and multiple RNAs structure comparison. The comparison results with two popular RNA

  14. A need for standardization in drinking water analysis – an investigation of DNA extraction procedure, primer choice and detection limit of 16S rRNA amplicon sequencing

    DEFF Research Database (Denmark)

    Brandt, Jakob; Nielsen, Per Halkjær; Albertsen, Mads

    Today 16S rRNA amplicon sequencing is a widely utilized technique for analyzing the bacterial community structure in drinking water. Concurrently with the prevalence of this method, the biases associated with 16S rRNA amplicon sequencing have been well-documented. However, no comprehensive attempts....... coli could be detected in all samples. However, samples with 101 cells/mL had several contaminating OTUs, constituting approximately 8% of the read abundances. For 16S rRNA gene analysis in drinking water samples, we recommend using the PowerWater DNA Isolation Kit for DNA extraction in combination...

  15. Bypassing rRNA methylation by RsmA/Dim1during ribosome maturation in the hyperthermophilic archaeon Nanoarchaeum equitans

    DEFF Research Database (Denmark)

    Seistrup, Kenneth H; Rose, Simon; Birkedal, Ulf

    2017-01-01

    In all free-living organisms a late-stage checkpoint in the biogenesis of the small ribosomal subunit involves rRNA modification by an RsmA/Dim1 methyltransferase. The hyperthermophilic archaeon Nanoarchaeum equitans, whose existence is confined to the surface of a second archaeon, Ignicoccus....... hospitalis to N. equitans across their fused cell membrane structures and the corresponding nucleotides in N. equitans 16S rRNA remain unmethylated. An alternative mechanism for ribosomal subunit maturation in N. equitans is suggested by sRNA interactions that span the redundant RsmA/Dim1 site to introduce 2...

  16. Dihydrofolate reductase: Sequential resonance assignments using 2D and 3D NMR and secondary structure determination in solution

    Energy Technology Data Exchange (ETDEWEB)

    Carr, M.D.; Birdsall, B.; Jimenez-Barbero, J.; Polshakov, V.I.; McCormick, J.E.; Feeney, J.; Frenkiel, T.A.; Bauer, C.J. (National Inst. for Medical Research, London (England)); Roberts, G.C.K. (Univ. of Leicester (England))

    1991-06-25

    Three-dimensional (3D) heteronuclear NMR techniques have been used to make sequential {sup 1}H and {sup 15}H resonance assignments for most of the residues of Lactobacillus casei dihydrofolate reductase (DHFR), a monomeric protein of molecular mass 18,300 Da. A uniformly {sup 15}N-labeled sample of the protein was prepared and its complex with methotrexate (MTX) studied by 3D {sup 15}N/{sup 1}H nuclear Overhauserheteronuclear multiple quantum coherence (NOESY-HMQC), Harmann-Hahn-heteronuclear multiple quantum coherence (HOHAHA-HMQC), and HMQC-NOESY-HMQC experiments. These experiments overcame most of the spectral overlap problems caused by chemical shift degeneracies in 2D spectra and allowed the {sup 1}H-{sup 1}H through-space and through-bond connectivities to be identified unambiguously, leading to the resonance assignments. The novel HMQC-NOESY-HMQC experiment allows NOE cross peaks to be detected between NH protons even when their {sup 1}H chemical shifts are degenerate as long as the amide {sup 15}N chemical shifts are nondegenerate. The 3D experiments, in combination with conventional 2D NOESY, COSY, and HOHAHA experiments on unlabelled and selectively deuterated DHFR, provide backbone assignments for 146 of the 162 residues and side-chain assignments for 104 residues of the protein. Data from the NOE-based experiments and identification of the slowly exchanging amide protons provide detailed information about the secondary structure of the binary complex of the protein with methotrexate.

  17. Ric-8A, a G protein chaperone with nucleotide exchange activity induces long-range secondary structure changes in Gα.

    Science.gov (United States)

    Kant, Ravi; Zeng, Baisen; Thomas, Celestine J; Bothner, Brian; Sprang, Stephen R

    2016-12-23

    Cytosolic Ric-8A has guanine nucleotide exchange factor (GEF) activity and is a chaperone for several classes of heterotrimeric G protein α subunits in vertebrates. Using Hydrogen-Deuterium Exchange-Mass Spectrometry (HDX-MS) we show that Ric-8A disrupts the secondary structure of the Gα Ras-like domain that girds the guanine nucleotide-binding site, and destabilizes the interface between the Gαi1 Ras and helical domains, allowing domain separation and nucleotide release. These changes are largely reversed upon binding GTP and dissociation of Ric-8A. HDX-MS identifies a potential Gα interaction site in Ric-8A. Alanine scanning reveals residues crucial for GEF activity within that sequence. HDX confirms that, like G protein-coupled receptors (GPCRs), Ric-8A binds the C-terminus of Gα. In contrast to GPCRs, Ric-8A interacts with Switches I and II of Gα and possibly at the Gα domain interface. These extensive interactions provide both allosteric and direct catalysis of GDP unbinding and release and GTP binding.

  18. DNA Barcoding Identification of Kadsurae Caulis and Spatholobi Caulis Based on Internal Transcribed Spacer 2 Region and Secondary Structure Prediction.

    Science.gov (United States)

    Yu, Xiaoxue; Xie, Zhiyong; Wu, Junwei; Tao, Junfei; Xu, Xinjun

    2016-05-01

    Kadsurae Caulis and Spatholobi Caulis have very similar Chinese names. Their commodities were hard to distinguish because their stems were very alike after dried and processed. These two herbal drugs were often mixed in clinical use. Authenticity assurance is crucial for quality control of herbal drugs. Therefore, it is essential to establish a method for identifying the two herbs. In this paper, we used the DNA barcoding technology, based on the internal transcribed spacer 2 (ITS2) regions, to differentiate Kadsurae Caulis and Spatholobi Caulis. The ITS2 of these two herbs were very different. They were successfully differentiated using the DNA barcoding technique. DNA barcoding was a promising and reliable tool for the identification of medicinal plants. It can be a powerful complementary method for traditional authentication. The internal transcribed spacer 2 (ITS2) regions between Kadsurae Caulis and Spatholobi Caulis varied considerably, totally 139 variable sitesSample 1 was not Kadsurae Caulis as it labeled, but it should be Spatholobi Caulis in fact based on ITS2 regionThe secondary structure can also separate Kadsurae Caulis and Spatholobi Caulis effectivelyDNA barcoding provided an accurate and strong prove to identify these two herbs. Abbreviations used: CTAB: hexadecyltrimethylammonium bromide, DNA: deoxyribonucleic acid, ITS2:internal transcribed spacer 2, PCR: polymerase chain reaction.

  19. 1H, 13C and 15N resonance assignments and secondary structures of cyclophilin 2 from Trichomonas vaginalis.

    Science.gov (United States)

    Martin, Tesmine; Lou, Yuan-Chao; Aryal, Sarita; Tai, Jung-Hsiang; Chen, Chinpan

    2017-09-05

    Cyclophilins are peptidyl prolyl isomerases that play an important role in a wide variety of biological functions like protein folding and trafficking, intracellular and extracellular signaling pathways, nuclear translocation and in pre-mRNA splicing. Two cyclophilins have been identified in the parasitic organism Trichomonas vaginalis and were named as TvCyP1 and TvCyP2. The 2 enzymes have been found to interact with Myb transcription factors in the parasite which regulate the iron induced expression of ap65-1 gene leading to cytoadherence of the parasite to human vaginal epithelial cells to cause the disease trichomoniasis. TvCyP2 was found to interact specifically with Myb3 to regulate nuclear translocation of the transcription factor. It would be intriguing to identify the binding site of both proteins as it could pave way to newer targets for drug discovery. Here we report the 1H, 13C and 15N resonance assignments and secondary structure information of TvCyP2 that could help us investigate the interaction between Myb3 and TvCyP2 in detail using NMR.

  20. Non-coding RNA identification based on topology secondary structure and reading frame in organelle genome level.

    Science.gov (United States)

    Wu, Cheng-Yan; Li, Qian-Zhong; Feng, Zhen-Xing

    2016-01-01

    Non-coding RNA (ncRNA) genes make transcripts as same as the encoding genes, and ncRNAs directly function as RNAs rather than serve as blueprints for proteins. As the function of ncRNA is closely related to organelle genomes, it is desirable to explore ncRNA function by confirming its provenance. In this paper, the topology secondary structure, motif and the triplets under three reading frames are considered as parameters of ncRNAs. A method of SVM combining the increment of diversity (ID) algorithm is applied to construct the classifier. When the method is applied to the ncRNA dataset less than 80% sequence identity, the overall accuracies reach 95.57%, 96.40% in the five-fold cross-validation and the jackknife test, respectively. Further, for the independent testing dataset, the average prediction success rate of our method achieved 93.24%. The higher predictive success rates indicate that our method is very helpful for distinguishing ncRNAs from various organelle genomes. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Protective spin-labeled fluorenes maintain amyloid beta peptide in small oligomers and limit transitions in secondary structure

    Energy Technology Data Exchange (ETDEWEB)

    Altman, Robin [Univ. of California, Davis, CA (United States). Dept. of Biochemistry and Molecular Medicine; Ly, Sonny [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Physical and Life Science Directorate; Hilt, Silvia [Univ. of California, Davis, CA (United States). Dept. of Biochemistry and Molecular Medicine; Petrlova, Jitka [Univ. of California, Davis, CA (United States). Dept. of Biochemistry and Molecular Medicine; Maezawa, Izumi [Univ. of California Davis, Sacramento, CA (United States). MIND Inst. and Dept. of Pathology and Laboratory Medicine; Kálai, Tamás [Univ. of Pecs (Hungary). Inst. of Organic and Medicinal Chemistry; Hideg, Kálmán [Univ. of Pecs (Hungary). Inst. of Organic and Medicinal Chemistry; Jin, Lee-Way [Univ. of California Davis, Sacramento, CA (United States). MIND Inst. and Dept. of Pathology and Laboratory Medicine; Laurence, Ted A. [Univ. of California, Davis, CA (United States). Dept. of Biochemistry and Molecular Medicine; Voss, John C. [Univ. of California, Davis, CA (United States). Dept. of Biochemistry and Molecular Medicine

    2015-12-01

    Alzheimer’s disease is characterized by the presence of extracellular plaques comprised of amyloid beta (Aβ) peptides. Soluble oligomers of the Aβ peptide underlie a cascade of neuronal loss and dysfunction associated with Alzheimer's disease. Single particle analyses of Aβ oligomers in solution by fluorescence correlation spectroscopy (FCS) were used to provide real-time descriptions of how spin-labeled fluorenes (SLFs; bi-functional small molecules that block the toxicity of Aβ) prevent and disrupt oligomeric assemblies of Aβ in solution. The FCS results, combined with electron paramagnetic resonance spectroscopy and circular dichroism spectroscopy, demonstrate SLFs can inhibit the growth of Aβ oligomers and disrupt existing oligomers while retaining Aβ in a largely disordered state. Furthermore, while the ability of SLF to block Aβ toxicity correlates with a reduction in oligomer size, our results suggest the conformation of Aβ within the oligomer determines the toxicity of the species. Attenuation of Aβ toxicity, which has been associated primarily with the soluble oligomeric form, can be achieved through redistribution of the peptides into smaller oligomers and arrest of the fractional increase in beta secondary structure.

  2. MicroRNA prediction using a fixed-order Markov model based on the secondary structure pattern.

    Directory of Open Access Journals (Sweden)

    Wei Shen

    Full Text Available Predicting miRNAs is an arduous task, due to the diversity of the precursors and complexity of enzyme processes. Although several prediction approaches have reached impressive performances, few of them could achieve a full-function recognition of mature miRNA directly from the candidate hairpins across species. Therefore, researchers continue to seek a more powerful model close to biological recognition to miRNA structure. In this report, we describe a novel miRNA prediction algorithm, known as FOMmiR, using a fixed-order Markov model based on the secondary structural pattern. For a training dataset containing 809 human pre-miRNAs and 6441 human pseudo-miRNA hairpins, the model's parameters were defined and evaluated. The results showed that FOMmiR reached 91% accuracy on the human dataset through 5-fold cross-validation. Moreover, for the independent test datasets, the FOMmiR presented an outstanding prediction in human and other species including vertebrates, Drosophila, worms and viruses, even plants, in contrast to the well-known algorithms and models. Especially, the FOMmiR was not only able to distinguish the miRNA precursors from the hairpins, but also locate the position and strand of the mature miRNA. Therefore, this study provides a new generation of miRNA prediction algorithm, which successfully realizes a full-function recognition of the mature miRNAs directly from the hairpin sequences. And it presents a new understanding of the biological recognition based on the strongest signal's location detected by FOMmiR, which might be closely associated with the enzyme cleavage mechanism during the miRNA maturation.

  3. Multi-site-specific 16S rRNA Methyltransferase RsmF from Thermus thermophilus

    Energy Technology Data Exchange (ETDEWEB)

    Demirci, H.; Larsen, L; Hansen, T; Rasmussen, A; Cadambi, A; Gregory, S; Kirpekar, F; Jogl, G

    2010-01-01

    Cells devote a significant effort toward the production of multiple modified nucleotides in rRNAs, which fine tune the ribosome function. Here, we report that two methyltransferases, RsmB and RsmF, are responsible for all four 5-methylcytidine (m{sup 5}C) modifications in 16S rRNA of Thermus thermophilus. Like Escherichia coli RsmB, T. thermophilus RsmB produces m{sup 5}C967. In contrast to E. coli RsmF, which introduces a single m{sup 5}C1407 modification, T. thermophilus RsmF modifies three positions, generating m{sup 5}C1400 and m{sup 5}C1404 in addition to m{sup 5}C1407. These three residues are clustered near the decoding site of the ribosome, but are situated in distinct structural contexts, suggesting a requirement for flexibility in the RsmF active site that is absent from the E. coli enzyme. Two of these residues, C1400 and C1404, are sufficiently buried in the mature ribosome structure so as to require extensive unfolding of the rRNA to be accessible to RsmF. In vitro, T. thermophilus RsmF methylates C1400, C1404, and C1407 in a 30S subunit substrate, but only C1400 and C1404 when naked 16S rRNA is the substrate. The multispecificity of T. thermophilus RsmF is potentially explained by three crystal structures of the enzyme in a complex with cofactor S-adenosyl-methionine at up to 1.3 {angstrom} resolution. In addition to confirming the overall structural similarity to E. coli RsmF, these structures also reveal that key segments in the active site are likely to be dynamic in solution, thereby expanding substrate recognition by T. thermophilus RsmF.

  4. Crystallization and X-ray diffraction data of Thermus flavus 5S rRNA helices

    Science.gov (United States)

    Vallazza, Marco; Senge, Andrea; Lippmann, Corinna; Perbandt, Markus; Betzel, Christian; Bald, Rolf; Erdmann, Volker A.

    2001-11-01

    5S rRNA is an essential component of the large ribosomal subunit in prokaryotes and eukaryotes. Its unknown function in the ribosome will eventually be revealed in part by structural studies. To promote crystallization and enhance resolution in X-ray diffraction the molecule was subdivided into five domains A-E. Several RNA oligonucleotides were chemically produced by solid-phase phosphoramidite synthesis in order to construct the domains of the 5S rRNA. An improved RNA-MPD-screen was applied in crystallization which covers a complete 2D matrix for the components used. Crystallization analysis resulted in preferred combinations of pH, polyamine, monovalent and divalent cations for short RNA molecules. Six types of crystals corresponding to the domains B, C and E of Thermus flavus 5S rRNA could be obtained which were suitable for X-ray diffraction. Four RNA helices consist of seven base pairs and two of eight base pairs. As special features, they contain two adenines in a bulge position or G : U wobble base pairs assumed to be involved in RNA-protein recognition. With an increase in crystal size an increase in resolution by X-ray analysis was observed. X-ray diffraction data were collected to 1.5 Å resolution using synchrotron radiation and cryogenic cooling techniques.

  5. Social Network Analyses (SNA) as a method to study the structure of contacts within teams of a school for secondary education

    NARCIS (Netherlands)

    Meijs, Celeste; De Laat, Maarten

    2017-01-01

    This paper reports findings from a study using social network analysis techniques to understand social learning relationships within and between teacher teams in a large secondary school in the Netherlands (n=117 teachers). The findings suggest a relationship between the social structure of a team

  6. Access to Higher Education at the End of Lower Secondary for "Disadvantaged" Students: The Interplay of Structural, Institutional Frameworks and Student Agency

    Science.gov (United States)

    Danic, Isabelle

    2015-01-01

    Drawing from quantitative and qualitative data collected by the European research project GOETE in eight European countries, the article focuses on the experiences of so-called "disadvantaged students" at the end of lower secondary and analyzes how access to higher education is negotiated in the interaction of structural/institutional…

  7. The influence of the binding of low molecular weight surfactants on the thermal stability and secondary structure of IgG

    NARCIS (Netherlands)

    Vermeer, AWP; Norde, W

    2000-01-01

    The effect of low molecular weight surfactants on the thermal stability of immunoglobulin G is studied by differential scanning calorimetry. The corresponding change in the secondary structure is investigated using circular dichroism spectroscopy and the rate of aggregate formation, both in the

  8. RNA secondary structures in a polymer-zeta model how foldings should be shaped for sparsification to establish a linear speedup

    DEFF Research Database (Denmark)

    Jin, Emma Yu; Nebel, M. E.

    2016-01-01

    algorithm. In this paper we discuss the application of the polymer-zeta property for the analysis of sparsification, showing that it must be applied conditionally on first and last positions to pair. Afterwards, we will investigate the combinatorics of RNA secondary structures assuming...

  9. The 5' untranslated mRNA region base content can greatly affect translation initiation in the absence of secondary structures in Prevotella bryantii TC1-1.

    Science.gov (United States)

    Seničar, Lenart; Accetto, Tomaž

    2015-01-01

    It has become clear lately that many bacteria and even whole bacterial phyla do not use the classical Shine-Dalgarno sequence mediated pathway of protein translation initiation. The prominent phylum Bacteroidetes is one of them, and this was shown not only using bioinformatic but also functional reporter gene studies in its representative Prevotella bryantii. The latter studies revealed much higher sensitivity toward secondary structures in 5(') untranslated mRNA regions (5(') UTRs) during translation initiation compared to Escherichia coli. It was proposed that in the absence of Shine-Dalgarno sequence interaction the key elements enabling translation initiation are local absence of secondary structures in 5(') UTRs, and the ribosomal protein S1 which binds to mRNA. Here, we evaluate the 5(') UTRs devoid of secondary structures but containing divergent nucleotide compositions in P. bryantii reporter assay. We show that base composition profoundly affects the amount of the reporter synthesized, and further that these amounts were in agreement with S1 protein binding affinity for adenine/uracil bases in mRNA. This is the first, though indirect, clue that S1 is actually involved in translation initiation in Bacteroidetes and adds the second layer of control beside mRNA secondary structure affecting translation initiation in this phylum. © FEMS 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  10. High throughput 16S rRNA gene amplicon sequencing

    DEFF Research Database (Denmark)

    Nierychlo, Marta; Larsen, Poul; Jørgensen, Mads Koustrup

    S rRNA gene amplicon sequencing has been developed over the past few years and is now ready to use for more comprehensive studies related to plant operation and optimization thanks to short analysis time, low cost, high throughput, and high taxonomic resolution. In this study we show how 16S r...

  11. GJB2 and mitochondrial 12S rRNA susceptibility mutations in sudden deafness.

    Science.gov (United States)

    Chen, Kaitian; Sun, Liang; Zong, Ling; Wu, Xuan; Zhan, Yuan; Dong, Chang; Cao, Hui; Tang, Haocheng; Jiang, Hongyan

    2016-06-01

    Genetic susceptibility may play an important role in the pathogenesis of sudden deafness. However, the specific genes involved are largely unknown. We sought to explore the frequency of GJB2 and mitochondrial 12S rRNA susceptibility mutations in patients with sudden deafness. Between September 2011 and May 2012, 62 consecutive patients with sudden deafness were seen. In 50 of these, no etiological factors for sudden deafness were found. We detected GJB2 and mitochondrial 12S rRNA variants by direct sequencing in these 50 patients and in 53-aged matched controls with normal hearing. In addition, we undertook functional analyses of the mitochondrial mutations which we detected, applying structural and phylogenetic analysis. GJB2 sequencing identified six mutations, including three pathogenic mutations (c.235delC, c.299-300delAT, c.109G>A) and three polymorphisms, in the study participants, giving an allele frequency of 15.0 %. A homozygous c.109G>A mutation was detected in two participants. A total of 16 variants in mitochondrial 12S rRNA gene were identified in the participants. No significant differences were found in GJB2 heterozygosity or in mitochondrial 12S rRNA variants between patients with sudden deafness and in controls. Our results suggest that the homozygous GJB2 c.109G>A mutation may be a cause of sudden deafness involving both ears. This finding should increase awareness of the likely role of genetic factors in the etiology of sudden deafness in general.

  12. Comparative analysis of the 5S rRNA and its associated proteins reveals unique primitive rather than parasitic features in Giardia lamblia.

    Science.gov (United States)

    Feng, Jin-Mei; Sun, Jun; Xin, De-Dong; Wen, Jian-Fan

    2012-01-01

    5S rRNA is a highly conserved ribosomal component. Eukaryotic 5S rRNA and its associated proteins (5S rRNA system) have become very well understood. Giardia lamblia was thought by some researchers to be the most primitive extant eukaryote while others considered it a highly evolved parasite. Previous reports have indicated that some aspects of its 5S rRNA system are simpler than that of common eukaryotes. We here explore whether this is true to its entire system, and whether this simplicity is a primitive or parasitic feature. By collecting and confirming pre-existing data and identifying new data, we obtained almost complete datasets of the system of three isolates of G. lamblia, two other parasitic excavates (Trichomonas vaginalis, Trypanosoma cruzi), and one free-living one (Naegleria gruberi). After comprehensively comparing each aspect of the system among these excavates and also with those of archaea and common eukaryotes, we found all the three Giardia isolates to harbor a same simplified 5S rRNA system, which is not only much simpler than that of common eukaryotes but also the simplest one among those of these excavates, and is surprisingly very similar to that of archaea; we also found among these excavates the system in parasitic species is not necessarily simpler than that in free-living species, conversely, the system of free-living species is even simpler in some respects than those of parasitic ones. The simplicity of Giardia 5S rRNA system should be considered a primitive rather than parasitically-degenerated feature. Therefore, Giardia 5S rRNA system might be a primitive system that is intermediate between that of archaea and the common eukaryotic model system, and it may reflect the evolutionary history of the eukaryotic 5S rRNA system from the archaeal form. Our results also imply G. lamblia might be a primitive eukaryote with secondary parasitically-degenerated features.

  13. Quantitative depth profiling of Si{sub 1–x}Ge{sub x} structures by time-of-flight secondary ion mass spectrometry and secondary neutral mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Drozdov, M.N.; Drozdov, Y.N. [Institute for Physics of Microstructures of the Russian Academy of Sciences (IPM RAS), 603950 Nizhniy Novgorod (Russian Federation); Lobachevski Nizhniy Novgorod State University, 603950 Nizhniy Novgorod (Russian Federation); Csik, A. [Institute for Nuclear Research (INR), Hungarian Academy of Science, Bem tér 18/C, 4026 Debrecen (Hungary); Novikov, A.V. [Institute for Physics of Microstructures of the Russian Academy of Sciences (IPM RAS), 603950 Nizhniy Novgorod (Russian Federation); Lobachevski Nizhniy Novgorod State University, 603950 Nizhniy Novgorod (Russian Federation); Vad, K. [Institute for Nuclear Research (INR), Hungarian Academy of Science, Bem tér 18/C, 4026 Debrecen (Hungary); Yunin, P.A.; Yurasov, D.V. [Institute for Physics of Microstructures of the Russian Academy of Sciences (IPM RAS), 603950 Nizhniy Novgorod (Russian Federation); Lobachevski Nizhniy Novgorod State University, 603950 Nizhniy Novgorod (Russian Federation); Belykh, S.F. [MATI Russian State Technological University, Orshanskaya Str. 3, 121552 Moscow (Russian Federation); Gololobov, G.P.; Suvorov, D.V. [Ryazan State Radio Engineering University, Gagarin Str. 59/1, 390005 Ryazan (Russian Federation); Tolstogouzov, A., E-mail: a.tolstoguzov@fct.unl.pt [Ryazan State Radio Engineering University, Gagarin Str. 59/1, 390005 Ryazan (Russian Federation); Centre for Physics and Technological Research (CeFITec), Dept. de Física da Faculdade de Ciências e Tecnologia (FCT), Universidade Nova de Lisboa, 2829-516 Caparica (Portugal)

    2016-05-31

    Quantification of Ge in Si{sub 1–x}Ge{sub x} structures (0.092 ≤ x ≤ 0.78) was carried out by time-of-flight secondary ion mass spectrometry (TOF-SIMS) and electron-gas secondary neutral mass spectrometry (SNMS). A good linear correlation (R{sup 2} > 0.9997) of the intensity ratios of secondary ions GeCs{sub 2}{sup +}/SiCs{sub 2}{sup +} and {sup 74}Ge{sup −}/{sup 30}Si{sup −} and post-ionized sputtered neutrals {sup 70}Ge{sup +}/{sup 28}Si{sup +} with Ge concentration was obtained. The calibration data were used for quantitative depth profiling of [10 × (12.3 nm Si{sub 0.63}Ge{sub 0.37}/34 nm Si)] structures on Si. Satisfactory compliance of the quantified Ge concentration in SiGe layers with the values obtained by high-resolution X-ray diffraction was revealed for both techniques. SIMS and SNMS experimental profiles were fitted using Hofmann's mixing-roughness-information depth (MRI) model. In the case of TOF-SIMS, the quality of the reconstruction was better than for SNMS since not only the progressing roughening, but also the crater effect and other processes unaccounted in the MRI simulation could have a significant impact on plasma sputter depth profiling.

  14. Experimental Investigation of Secondary Flow Structures Downstream of a Model Type IV Stent Failure in a 180° Curved Artery Test Section.

    Science.gov (United States)

    Bulusu, Kartik V; Plesniak, Michael W

    2016-07-19

    The arterial network in the human vasculature comprises of ubiquitously present blood vessels with complex geometries (branches, curvatures and tortuosity). Secondary flow structures are vortical flow patterns that occur in curved arteries due to the combined action of centrifugal forces, adverse pressure gradients and inflow characteristics. Such flow morphologies are greatly affected by pulsatility and multiple harmonics of physiological inflow conditions and vary greatly in size-strength-shape characteristics compared to non-physiological (steady and oscillatory) flows (1 - 7). Secondary flow structures may ultimately influence the wall shear stress and exposure time of blood-borne particles toward progression of atherosclerosis, restenosis, sensitization of platelets and thrombosis (4 - 6, 8 - 13). Therefore, the ability to detect and characterize these