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Sample records for yeast pheromone-responsive pathway

  1. Constitutive Activation of the Fission Yeast Pheromone-Responsive Pathway Induces Ectopic Meiosis and Reveals Ste11 as a Mitogen-Activated Protein Kinase Target

    DEFF Research Database (Denmark)

    Kjærulff, Søren; Lautrup-Larsen, I.; Truelsen, S.

    2005-01-01

    In the fission yeast Schizosaccharomyces pombe, meiosis normally takes place in diploid zygotes resulting from conjugation of haploid cells. In the present study, we report that the expression of a constitutively activated version of the pheromone-responsive mitogen-activated protein kinase kinase...... found that haploid meiosis was dramatically reduced when Ste11 was mutated to mimic phosphorylation by Pat1. The mutation of two putative MAPK sites in Ste11 also dramatically reduced the level of haploid meiosis, suggesting that Ste11 is a direct target of Spk1. Supporting this, we show that Spk1 can...... interact physically with Ste11 and also phosphorylate the transcription factor in vitro. Finally, we demonstrate that ste11 is required for pheromone-induced G1 arrest. Interestingly, when we mutated Ste11 in the sites for Pat1 and Spk1 phosphorylation simultaneously, the cells could still arrest in G1...

  2. Heterotrimeric G Protein-coupled Receptor Signaling in Yeast Mating Pheromone Response.

    Science.gov (United States)

    Alvaro, Christopher G; Thorner, Jeremy

    2016-04-08

    The DNAs encoding the receptors that respond to the peptide mating pheromones of the budding yeastSaccharomyces cerevisiaewere isolated in 1985, and were the very first genes for agonist-binding heterotrimeric G protein-coupled receptors (GPCRs) to be cloned in any organism. Now, over 30 years later, this yeast and its receptors continue to provide a pathfinding experimental paradigm for investigating GPCR-initiated signaling and its regulation, as described in this retrospective overview. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  3. Stochasticity in the yeast mating pathway

    International Nuclear Information System (INIS)

    Hong-Li, Wang; Zheng-Ping, Fu; Xin-Hang, Xu; Qi, Ouyang

    2009-01-01

    We report stochastic simulations of the yeast mating signal transduction pathway. The effects of intrinsic and external noise, the influence of cell-to-cell difference in the pathway capacity, and noise propagation in the pathway have been examined. The stochastic temporal behaviour of the pathway is found to be robust to the influence of inherent fluctuations, and intrinsic noise propagates in the pathway in a uniform pattern when the yeasts are treated with pheromones of different stimulus strengths and of varied fluctuations. In agreement with recent experimental findings, extrinsic noise is found to play a more prominent role than intrinsic noise in the variability of proteins. The occurrence frequency for the reactions in the pathway are also examined and a more compact network is obtained by dropping most of the reactions of least occurrence

  4. Making Sense of the Yeast Sphingolipid Pathway.

    Science.gov (United States)

    Megyeri, Márton; Riezman, Howard; Schuldiner, Maya; Futerman, Anthony H

    2016-12-04

    Sphingolipids (SL) and their metabolites play key roles both as structural components of membranes and as signaling molecules. Many of the key enzymes and regulators of SL metabolism were discovered using the yeast Saccharomyces cerevisiae, and based on the high degree of conservation, a number of mammalian homologs were identified. Although yeast continues to be an important tool for SL research, the complexity of SL structure and nomenclature often hampers the ability of new researchers to grasp the subtleties of yeast SL biology and discover new modulators of this intricate pathway. Moreover, the emergence of lipidomics by mass spectrometry has enabled the rapid identification of SL species in yeast and rendered the analysis of SL composition under various physiological and pathophysiological conditions readily amenable. However, the complex nomenclature of the identified species renders much of the data inaccessible to non-specialists. In this review, we focus on parsing both the classical SL nomenclature and the nomenclature normally used during mass spectrometry analysis, which should facilitate the understanding of yeast SL data and might shed light on biological processes in which SLs are involved. Finally, we discuss a number of putative roles of various yeast SL species. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. MAP kinase pathways in the yeast Saccharomyces cerevisiae

    Science.gov (United States)

    Gustin, M. C.; Albertyn, J.; Alexander, M.; Davenport, K.; McIntire, L. V. (Principal Investigator)

    1998-01-01

    A cascade of three protein kinases known as a mitogen-activated protein kinase (MAPK) cascade is commonly found as part of the signaling pathways in eukaryotic cells. Almost two decades of genetic and biochemical experimentation plus the recently completed DNA sequence of the Saccharomyces cerevisiae genome have revealed just five functionally distinct MAPK cascades in this yeast. Sexual conjugation, cell growth, and adaptation to stress, for example, all require MAPK-mediated cellular responses. A primary function of these cascades appears to be the regulation of gene expression in response to extracellular signals or as part of specific developmental processes. In addition, the MAPK cascades often appear to regulate the cell cycle and vice versa. Despite the success of the gene hunter era in revealing these pathways, there are still many significant gaps in our knowledge of the molecular mechanisms for activation of these cascades and how the cascades regulate cell function. For example, comparison of different yeast signaling pathways reveals a surprising variety of different types of upstream signaling proteins that function to activate a MAPK cascade, yet how the upstream proteins actually activate the cascade remains unclear. We also know that the yeast MAPK pathways regulate each other and interact with other signaling pathways to produce a coordinated pattern of gene expression, but the molecular mechanisms of this cross talk are poorly understood. This review is therefore an attempt to present the current knowledge of MAPK pathways in yeast and some directions for future research in this area.

  6. Drug synergy drives conserved pathways to increase fission yeast lifespan.

    Directory of Open Access Journals (Sweden)

    Xinhe Huang

    Full Text Available Aging occurs over time with gradual and progressive loss of physiological function. Strategies to reduce the rate of functional loss and mitigate the subsequent onset of deadly age-related diseases are being sought. We demonstrated previously that a combination of rapamycin and myriocin reduces age-related functional loss in the Baker's yeast Saccharomyces cerevisiae and produces a synergistic increase in lifespan. Here we show that the same drug combination also produces a synergistic increase in the lifespan of the fission yeast Schizosaccharomyces pombe and does so by controlling signal transduction pathways conserved across a wide evolutionary time span ranging from yeasts to mammals. Pathways include the target of rapamycin complex 1 (TORC1 protein kinase, the protein kinase A (PKA and a stress response pathway, which in fission yeasts contains the Sty1 protein kinase, an ortholog of the mammalian p38 MAP kinase, a type of Stress Activated Protein Kinase (SAPK. These results along with previous studies in S. cerevisiae support the premise that the combination of rapamycin and myriocin enhances lifespan by regulating signaling pathways that couple nutrient and environmental conditions to cellular processes that fine-tune growth and stress protection in ways that foster long term survival. The molecular mechanisms for fine-tuning are probably species-specific, but since they are driven by conserved nutrient and stress sensing pathways, the drug combination may enhance survival in other organisms.

  7. Yeast signaling pathways in the oxidative stress response

    Energy Technology Data Exchange (ETDEWEB)

    Ikner, Aminah [Section of Microbiology, Division of Biological Sciences, University of California, Davis, CA 95616 (United States); Shiozaki, Kazuhiro [Section of Microbiology, Division of Biological Sciences, University of California, Davis, CA 95616 (United States)]. E-mail: kshiozaki@ucdavis.edu

    2005-01-06

    Oxidative stress that generates the reactive oxygen species (ROS) is one of the major causes of DNA damage and mutations. The 'DNA damage checkpoint' that arrests cell cycle and repairs damaged DNA has been a focus of recent studies, and the genetically amenable model systems provided by yeasts have been playing a leading role in the eukaryotic checkpoint research. However, means to eliminate ROS are likely to be as important as the DNA repair mechanisms in order to suppress mutations in the chromosomal DNA, and yeasts also serve as excellent models to understand how eukaryotes combat oxidative stress. In this article, we present an overview of the signaling pathways that sense oxidative stress and induce expression of various anti-oxidant genes in the budding yeast Saccharomyces cerevisiae, the fission yeast Schizosaccharomyces pombe and the pathogenic yeast Candida albicans. Three conserved signaling modules have been identified in the oxidative stress response of these diverse yeast species: the stress-responsive MAP kinase cascade, the multistep phosphorelay and the AP-1-like transcription factor. The structure and function of these signaling modules are discussed.

  8. Yeast signaling pathways in the oxidative stress response

    International Nuclear Information System (INIS)

    Ikner, Aminah; Shiozaki, Kazuhiro

    2005-01-01

    Oxidative stress that generates the reactive oxygen species (ROS) is one of the major causes of DNA damage and mutations. The 'DNA damage checkpoint' that arrests cell cycle and repairs damaged DNA has been a focus of recent studies, and the genetically amenable model systems provided by yeasts have been playing a leading role in the eukaryotic checkpoint research. However, means to eliminate ROS are likely to be as important as the DNA repair mechanisms in order to suppress mutations in the chromosomal DNA, and yeasts also serve as excellent models to understand how eukaryotes combat oxidative stress. In this article, we present an overview of the signaling pathways that sense oxidative stress and induce expression of various anti-oxidant genes in the budding yeast Saccharomyces cerevisiae, the fission yeast Schizosaccharomyces pombe and the pathogenic yeast Candida albicans. Three conserved signaling modules have been identified in the oxidative stress response of these diverse yeast species: the stress-responsive MAP kinase cascade, the multistep phosphorelay and the AP-1-like transcription factor. The structure and function of these signaling modules are discussed

  9. Identification and Characterization of Components of the Mitotic Spindle Checkpoint Pathway in Fission Yeast

    National Research Council Canada - National Science Library

    Kadura, Shelia

    2001-01-01

    .... The fission yeast, Schizosaccharomyces pombe, is a useful system for discovering and characterizing components of this regulatory pathway because genetic approaches can be coupled with excellent cytology...

  10. Novel Pathway for Alcoholic Fermentation of 8-Gluconolactone in the Yeast Saccharomyces bulderi

    NARCIS (Netherlands)

    Dijken, van J.P.; Tuijl, van A.; Luttik, M.A.H.; Middelhoven, W.J.; Pronk, J.T.

    2002-01-01

    Under anaerobic conditions, the yeast Saccharomyces bulderi rapidly ferments -gluconolactone to ethanol and carbon dioxide. We propose that a novel pathway for -gluconolactone fermentation operates in this yeast. In this pathway, -gluconolactone is first reduced to glucose via an NADPH-dependent

  11. A yeast pheromone-based inter-species communication system.

    Science.gov (United States)

    Hennig, Stefan; Clemens, André; Rödel, Gerhard; Ostermann, Kai

    2015-02-01

    We report on a pheromone-based inter-species communication system, allowing for a controlled cell-cell communication between the two species Saccharomyces cerevisiae and Schizosaccharomyces pombe as a proof of principle. It exploits the mating response pathways of the two yeast species employing the pheromones, α- or P-factor, as signaling molecules. The authentic and chimeric pheromone-encoding genes were engineered to code for the P-factor in S. cerevisiae and the α-factor in S. pombe. Upon transformation of the respective constructs, cells were enabled to express the mating pheromone of the opposite species. The supernatant of cultures of S. pombe cells expressing α-factor were able to induce a G1 arrest in the cell cycle, a change in morphology to the typical shmoo effect and expression driven by the pheromone-responsive FIG1 promoter in S. cerevisiae. The supernatant of cultures of S. cerevisiae cells expressing P-factor similarly induced cell cycle arrest in G1, an alteration in morphology typical for mating as well as the activation of the pheromone-responsive promoters of the rep1 and sxa2 genes in a pheromone-hypersensitive reporter strain of S. pombe. Apparently, both heterologous pheromones were correctly processed and secreted in an active form by the cells of the other species. Our data clearly show that the species-specific pheromone systems of yeast species can be exploited for a controlled inter-species communication.

  12. An overview of bioinformatics methods for modeling biological pathways in yeast.

    Science.gov (United States)

    Hou, Jie; Acharya, Lipi; Zhu, Dongxiao; Cheng, Jianlin

    2016-03-01

    The advent of high-throughput genomics techniques, along with the completion of genome sequencing projects, identification of protein-protein interactions and reconstruction of genome-scale pathways, has accelerated the development of systems biology research in the yeast organism Saccharomyces cerevisiae In particular, discovery of biological pathways in yeast has become an important forefront in systems biology, which aims to understand the interactions among molecules within a cell leading to certain cellular processes in response to a specific environment. While the existing theoretical and experimental approaches enable the investigation of well-known pathways involved in metabolism, gene regulation and signal transduction, bioinformatics methods offer new insights into computational modeling of biological pathways. A wide range of computational approaches has been proposed in the past for reconstructing biological pathways from high-throughput datasets. Here we review selected bioinformatics approaches for modeling biological pathways inS. cerevisiae, including metabolic pathways, gene-regulatory pathways and signaling pathways. We start with reviewing the research on biological pathways followed by discussing key biological databases. In addition, several representative computational approaches for modeling biological pathways in yeast are discussed. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  13. Stochasticity in the enterococcal sex pheromone response revealed by quantitative analysis of transcription in single cells.

    Science.gov (United States)

    Breuer, Rebecca J; Bandyopadhyay, Arpan; O'Brien, Sofie A; Barnes, Aaron M T; Hunter, Ryan C; Hu, Wei-Shou; Dunny, Gary M

    2017-07-01

    In Enterococcus faecalis, sex pheromone-mediated transfer of antibiotic resistance plasmids can occur under unfavorable conditions, for example, when inducing pheromone concentrations are low and inhibiting pheromone concentrations are high. To better understand this paradox, we adapted fluorescence in situ hybridization chain reaction (HCR) methodology for simultaneous quantification of multiple E. faecalis transcripts at the single cell level. We present direct evidence for variability in the minimum period, maximum response level, and duration of response of individual cells to a specific inducing condition. Tracking of induction patterns of single cells temporally using a fluorescent reporter supported HCR findings. It also revealed subpopulations of rapid responders, even under low inducing pheromone concentrations where the overall response of the entire population was slow. The strong, rapid induction of small numbers of cells in cultures exposed to low pheromone concentrations is in agreement with predictions of a stochastic model of the enterococcal pheromone response. The previously documented complex regulatory circuitry controlling the pheromone response likely contributes to stochastic variation in this system. In addition to increasing our basic understanding of the biology of a horizontal gene transfer system regulated by cell-cell signaling, demonstration of the stochastic nature of the pheromone response also impacts any future efforts to develop therapeutic agents targeting the system. Quantitative single cell analysis using HCR also has great potential to elucidate important bacterial regulatory mechanisms not previously amenable to study at the single cell level, and to accelerate the pace of functional genomic studies.

  14. Multiple pathways for vacuolar sorting of yeast proteinase A

    DEFF Research Database (Denmark)

    Westphal, V; Marcusson, E G; Winther, Jakob R.

    1996-01-01

    The sorting of the yeast proteases proteinase A and carboxypeptidase Y to the vacuole is a saturable, receptor-mediated process. Information sufficient for vacuolar sorting of the normally secreted protein invertase has in fusion constructs previously been found to reside in the propeptide...

  15. The CWI Pathway: Regulation of the Transcriptional Adaptive Response to Cell Wall Stress in Yeast

    Directory of Open Access Journals (Sweden)

    Ana Belén Sanz

    2017-12-01

    Full Text Available Fungi are surrounded by an essential structure, the cell wall, which not only confers cell shape but also protects cells from environmental stress. As a consequence, yeast cells growing under cell wall damage conditions elicit rescue mechanisms to provide maintenance of cellular integrity and fungal survival. Through transcriptional reprogramming, yeast modulate the expression of genes important for cell wall biogenesis and remodeling, metabolism and energy generation, morphogenesis, signal transduction and stress. The yeast cell wall integrity (CWI pathway, which is very well conserved in other fungi, is the key pathway for the regulation of this adaptive response. In this review, we summarize the current knowledge of the yeast transcriptional program elicited to counterbalance cell wall stress situations, the role of the CWI pathway in the regulation of this program and the importance of the transcriptional input received by other pathways. Modulation of this adaptive response through the CWI pathway by positive and negative transcriptional feedbacks is also discussed. Since all these regulatory mechanisms are well conserved in pathogenic fungi, improving our knowledge about them will have an impact in the developing of new antifungal therapies.

  16. Analysis of Protein Localization and Secretory Pathway Function Using the Yeast "Saccharomyces Cerevisiae"

    Science.gov (United States)

    Vallen, Elizabeth

    2002-01-01

    The isolation and characterization of mutants has been crucial in understanding a number of processes in the field of cell biology. In this exercise, students examine the effects of mutations in the secretory pathway on protein localization. Yeast strains deficient for synthesis of histidinol dehydrogenase are transformed with a plasmid encoding a…

  17. Oxidative stress response pathways: Fission yeast as archetype

    DEFF Research Database (Denmark)

    Papadakis, Manos A.; Workman, Christopher

    2015-01-01

    Schizosaccharomyces pombe is a popular model eukaryotic organism to study diverse aspects of mammalian biology, including responses to cellular stress triggered by redox imbalances within its compartments. The review considers the current knowledge on the signaling pathways that govern the transc...

  18. Reconstitution in yeast of the Arabidopsis SOS signaling pathway for Na+ homeostasis

    OpenAIRE

    Quintero, Francisco J.; Ohta, Masaru; Shi, Huazhong; Zhu, Jian-Kang; Pardo, José M.

    2002-01-01

    The Arabidopsis thaliana SOS1 protein is a putative Na H antiporter that functions in Na extrusion and is essential for the NaCl tolerance of plants. sos1 mutant plants share phenotypic similarities with mutants lacking the protein kinase SOS2 and the Ca2 sensor SOS3. To investigate whether the three SOS proteins function in the same response pathway, we have reconstituted the SOS system in yeast cells. Expression of SOS1 improved the Na tolerance of yeast mutants la...

  19. A genetic and pharmacological analysis of isoprenoid pathway by LC-MS/MS in fission yeast.

    Directory of Open Access Journals (Sweden)

    Tomonori Takami

    Full Text Available Currently, statins are the only drugs acting on the mammalian isoprenoid pathway. The mammalian genes in this pathway are not easily amenable to genetic manipulation. Thus, it is difficult to study the effects of the inhibition of various enzymes on the intermediate and final products in the isoprenoid pathway. In fission yeast, antifungal compounds such as azoles and terbinafine are available as inhibitors of the pathway in addition to statins, and various isoprenoid pathway mutants are also available. Here in these mutants, treated with statins or antifungals, we quantified the final and intermediate products of the fission yeast isoprenoid pathway using liquid chromatography-mass spectrometry/mass spectrometry. In hmg1-1, a mutant of the gene encoding 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR, ergosterol (a final sterol product, and squalene (an intermediate pathway product, were decreased to approximately 80% and 10%, respectively, compared with that of wild-type cells. Consistently in wild-type cells, pravastatin, an HMGR inhibitor decreased ergosterol and squalene, and the effect was more pronounced on squalene. In hmg1-1 mutant and in wild-type cells treated with pravastatin, the decrease in the levels of farnesyl pyrophosphate and geranylgeranyl pyrophosphate respectively was larger than that of ergosterol but was smaller than that of squalene. In Δerg6 or Δsts1 cells, mutants of the genes involved in the last step of the pathway, ergosterol was not detected, and the changes of intermediate product levels were distinct from that of hmg1-1 mutant. Notably, in wild-type cells miconazole and terbinafine only slightly decreased ergosterol level. Altogether, these studies suggest that the pleiotropic phenotypes caused by the hmg1-1 mutation and pravastatin might be due to decreased levels of isoprenoid pyrophosphates or other isoprenoid pathway intermediate products rather than due to a decreased ergosterol level.

  20. A quantitative characterization of the yeast heterotrimeric G protein cycle

    Science.gov (United States)

    Yi, Tau-Mu; Kitano, Hiroaki; Simon, Melvin I.

    2003-01-01

    The yeast mating response is one of the best understood heterotrimeric G protein signaling pathways. Yet, most descriptions of this system have been qualitative. We have quantitatively characterized the heterotrimeric G protein cycle in yeast based on direct in vivo measurements. We used fluorescence resonance energy transfer to monitor the association state of cyan fluorescent protein (CFP)-Gα and Gβγ-yellow fluorescent protein (YFP), and we found that receptor-mediated G protein activation produced a loss of fluorescence resonance energy transfer. Quantitative time course and dose–response data were obtained for both wild-type and mutant cells possessing an altered pheromone response. These results paint a quantitative portrait of how regulators such as Sst2p and the C-terminal tail of α-factor receptor modulate the kinetics and sensitivity of G protein signaling. We have explored critical features of the dynamics including the rapid rise and subsequent decline of active G proteins during the early response, and the relationship between the G protein activation dose–response curve and the downstream dose–response curves for cell-cycle arrest and transcriptional induction. Fitting the data to a mathematical model produced estimates of the in vivo rates of heterotrimeric G protein activation and deactivation in yeast. PMID:12960402

  1. Yeast as a Tool to Study Signaling Pathways in Mitochondrial Stress Response and Cytoprotection

    Directory of Open Access Journals (Sweden)

    Maša Ždralević

    2012-01-01

    Full Text Available Cell homeostasis results from the balance between cell capability to adapt or succumb to environmental stress. Mitochondria, in addition to supplying cellular energy, are involved in a range of processes deciding about cellular life or death. The crucial role of mitochondria in cell death is well recognized. Mitochondrial dysfunction has been associated with the death process and the onset of numerous diseases. Yet, mitochondrial involvement in cellular adaptation to stress is still largely unexplored. Strong interest exists in pharmacological manipulation of mitochondrial metabolism and signaling. The yeast Saccharomyces cerevisiae has proven a valuable model organism in which several intracellular processes have been characterized in great detail, including the retrograde response to mitochondrial dysfunction and, more recently, programmed cell death. In this paper we review experimental evidences of mitochondrial involvement in cytoprotection and propose yeast as a model system to investigate the role of mitochondria in the cross-talk between prosurvival and prodeath pathways.

  2. Coordinated regulation of intracellular pH by two glucose-sensing pathways in yeast.

    Science.gov (United States)

    Isom, Daniel G; Page, Stephani C; Collins, Leonard B; Kapolka, Nicholas J; Taghon, Geoffrey J; Dohlman, Henrik G

    2018-02-16

    The yeast Saccharomyces cerevisiae employs multiple pathways to coordinate sugar availability and metabolism. Glucose and other sugars are detected by a G protein-coupled receptor, Gpr1, as well as a pair of transporter-like proteins, Rgt2 and Snf3. When glucose is limiting, however, an ATP-driven proton pump (Pma1) is inactivated, leading to a marked decrease in cytoplasmic pH. Here we determine the relative contribution of the two sugar-sensing pathways to pH regulation. Whereas cytoplasmic pH is strongly dependent on glucose abundance and is regulated by both glucose-sensing pathways, ATP is largely unaffected and therefore cannot account for the changes in Pma1 activity. These data suggest that the pH is a second messenger of the glucose-sensing pathways. We show further that different sugars differ in their ability to control cellular acidification, in the manner of inverse agonists. We conclude that the sugar-sensing pathways act via Pma1 to invoke coordinated changes in cellular pH and metabolism. More broadly, our findings support the emerging view that cellular systems have evolved the use of pH signals as a means of adapting to environmental stresses such as those caused by hypoxia, ischemia, and diabetes. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

  3. Understanding bistability in yeast glycolysis using general properties of metabolic pathways.

    Science.gov (United States)

    Planqué, Robert; Bruggeman, Frank J; Teusink, Bas; Hulshof, Josephus

    2014-09-01

    Glycolysis is the central pathway in energy metabolism in the majority of organisms. In a recent paper, van Heerden et al. showed experimentally and computationally that glycolysis can exist in two states, a global steady state and a so-called imbalanced state. In the imbalanced state, intermediary metabolites accumulate at low levels of ATP and inorganic phosphate. It was shown that Baker's yeast uses a peculiar regulatory mechanism--via trehalose metabolism--to ensure that most yeast cells reach the steady state and not the imbalanced state. Here we explore the apparent bistable behaviour in a core model of glycolysis that is based on a well-established detailed model, and study in great detail the bifurcation behaviour of solutions, without using any numerical information on parameter values. We uncover a rich suite of solutions, including so-called imbalanced states, bistability, and oscillatory behaviour. The techniques employed are generic, directly suitable for a wide class of biochemical pathways, and could lead to better analytical treatments of more detailed models. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Characterization of yeast extracellular vesicles: evidence for the participation of different pathways of cellular traffic in vesicle biogenesis.

    Directory of Open Access Journals (Sweden)

    Débora L Oliveira

    2010-06-01

    Full Text Available Extracellular vesicles in yeast cells are involved in the molecular traffic across the cell wall. In yeast pathogens, these vesicles have been implicated in the transport of proteins, lipids, polysaccharide and pigments to the extracellular space. Cellular pathways required for the biogenesis of yeast extracellular vesicles are largely unknown.We characterized extracellular vesicle production in wild type (WT and mutant strains of the model yeast Saccharomyces cerevisiae using transmission electron microscopy in combination with light scattering analysis, lipid extraction and proteomics. WT cells and mutants with defective expression of Sec4p, a secretory vesicle-associated Rab GTPase essential for Golgi-derived exocytosis, or Snf7p, which is involved in multivesicular body (MVB formation, were analyzed in parallel. Bilayered vesicles with diameters at the 100-300 nm range were found in extracellular fractions from yeast cultures. Proteomic analysis of vesicular fractions from the cells aforementioned and additional mutants with defects in conventional secretion pathways (sec1-1, fusion of Golgi-derived exocytic vesicles with the plasma membrane; bos1-1, vesicle targeting to the Golgi complex or MVB functionality (vps23, late endosomal trafficking revealed a complex and interrelated protein collection. Semi-quantitative analysis of protein abundance revealed that mutations in both MVB- and Golgi-derived pathways affected the composition of yeast extracellular vesicles, but none abrogated vesicle production. Lipid analysis revealed that mutants with defects in Golgi-related components of the secretory pathway had slower vesicle release kinetics, as inferred from intracellular accumulation of sterols and reduced detection of these lipids in vesicle fractions in comparison with WT cells.Our results suggest that both conventional and unconventional pathways of secretion are required for biogenesis of extracellular vesicles, which demonstrate the

  5. Impaired mastication reduced newly generated neurons at the accessory olfactory bulb and pheromonal responses in mice.

    Science.gov (United States)

    Utsugi, Chizuru; Miyazono, Sadaharu; Osada, Kazumi; Matsuda, Mitsuyoshi; Kashiwayanagi, Makoto

    2014-12-01

    A large number of neurons are generated at the subventricular zone (SVZ) even during adulthood. In a previous study, we have shown that a reduced mastication impairs both neurogenesis in the SVZ and olfactory functions. Pheromonal signals, which are received by the vomeronasal organ, provide information about reproductive and social states. Vomeronasal sensory neurons project to the accessory olfactory bulb (AOB) located on the dorso-caudal surface of the main olfactory bulb. Newly generated neurons at the SVZ migrate to the AOB and differentiate into granule cells and periglomerular cells. This study aimed to explore the effects of changes in mastication on newly generated neurons and pheromonal responses. Bromodeoxyuridine-immunoreactive (BrdU-ir; a marker of DNA synthesis) and Fos-ir (a marker of neurons excited) structures in sagittal sections of the AOB after exposure to urinary odours were compared between the mice fed soft and hard diets. The density of BrdU-ir cells in the AOB in the soft-diet-fed mice after 1 month was essentially similar to that of the hard-diet-fed mice, while that was lower in the soft-diet-fed mice for 3 or 6 months than in the hard-diet-fed mice. The density of Fos-ir cells in the soft-diet-fed mice after 2 months was essentially similar to that in the hard-diet-fed mice, while that was lower in the soft-diet-fed mice for 4 months than in the hard-diet-fed mice. The present results suggest that impaired mastication reduces newly generated neurons at the AOB, which in turn impairs olfactory function at the AOB. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Kinetic studies of the yeast His-Asp phosphorelay signaling pathway

    Science.gov (United States)

    Kaserer, Alla O.; Andi, Babak; Cook, Paul F.; West, Ann H.

    2010-01-01

    For both prokaryotic and eukaryotic His-Asp phosphorelay signaling pathways, the rates of protein phosphorylation and dephosphorylation determine the stimulus-to-response time frame. Thus, kinetic studies of phosphoryl group transfer between signaling partners are important for gaining a full understanding of how the system is regulated. In many cases, the phosphotransfer reactions are too fast for rates to be determined by manual experimentation. Rapid quench flow techniques thus provide a powerful method for studying rapid reactions that occur in the millisecond time frame. In this chapter, we describe experimental design and procedures for kinetic characterization of the yeast SLN1-YPD1-SSK1 osmoregulatory phosphorelay system using a rapid quench flow kinetic instrument. PMID:20946842

  7. Components of a Fanconi-like pathway control Pso2-independent DNA interstrand crosslink repair in yeast.

    Directory of Open Access Journals (Sweden)

    Thomas A Ward

    Full Text Available Fanconi anemia (FA is a devastating genetic disease, associated with genomic instability and defects in DNA interstrand cross-link (ICL repair. The FA repair pathway is not thought to be conserved in budding yeast, and although the yeast Mph1 helicase is a putative homolog of human FANCM, yeast cells disrupted for MPH1 are not sensitive to ICLs. Here, we reveal a key role for Mph1 in ICL repair when the Pso2 exonuclease is inactivated. We find that the yeast FANCM ortholog Mph1 physically and functionally interacts with Mgm101, a protein previously implicated in mitochondrial DNA repair, and the MutSα mismatch repair factor (Msh2-Msh6. Co-disruption of MPH1, MGM101, MSH6, or MSH2 with PSO2 produces a lesion-specific increase in ICL sensitivity, the elevation of ICL-induced chromosomal rearrangements, and persistence of ICL-associated DNA double-strand breaks. We find that Mph1-Mgm101-MutSα directs the ICL-induced recruitment of Exo1 to chromatin, and we propose that Exo1 is an alternative 5'-3' exonuclease utilised for ICL repair in the absence of Pso2. Moreover, ICL-induced Rad51 chromatin loading is delayed when both Pso2 and components of the Mph1-Mgm101-MutSα and Exo1 pathway are inactivated, demonstrating that the homologous recombination stages of ICL repair are inhibited. Finally, the FANCJ- and FANCP-related factors Chl1 and Slx4, respectively, are also components of the genetic pathway controlled by Mph1-Mgm101-MutSα. Together this suggests that a prototypical FA-related ICL repair pathway operates in budding yeast, which acts redundantly with the pathway controlled by Pso2, and is required for the targeting of Exo1 to chromatin to execute ICL repair.

  8. Mutations in cyr1 and pat1 reveal pheromone-induced G1 arrest in the fission yeast Schizosaccharomyces pombe

    DEFF Research Database (Denmark)

    Davey, William John; Nielsen, O; Nielsen, Olaf

    1994-01-01

    Investigations into sexual differentiation and pheromone response in the fission yeast Schizosaccharomyces pombe are complicated by the need to first starve the cells of nitrogen. Most mating-related experiments are therefore performed on non-dividing cells. Here we overcome this problem by using...

  9. Engineering of the glycerol decomposition pathway and cofactor regulation in an industrial yeast improves ethanol production.

    Science.gov (United States)

    Zhang, Liang; Tang, Yan; Guo, Zhongpeng; Shi, Guiyang

    2013-10-01

    Glycerol is a major by-product of industrial ethanol production and its formation consumes up to 4 % of the sugar substrate. This study modified the glycerol decomposition pathway of an industrial strain of Saccharomyces cerevisiae to optimize the consumption of substrate and yield of ethanol. This study is the first to couple glycerol degradation with ethanol formation, to the best of our knowledge. The recombinant strain overexpressing GCY1 and DAK1, encoding glycerol dehydrogenase and dihydroxyacetone kinase, respectively, in glycerol degradation pathway, exhibited a moderate increase in ethanol yield (2.9 %) and decrease in glycerol yield (24.9 %) compared to the wild type with the initial glucose concentration of 15 % under anaerobic conditions. However, when the mhpF gene, encoding acetylating NAD⁺-dependent acetaldehyde dehydrogenase from Escherichia coli, was co-expressed in the aforementioned recombinant strain, a further increase in ethanol yield by 5.5 % and decrease in glycerol yield by 48 % were observed for the resultant recombinant strain GDMS1 when acetic acid was added into the medium prior to inoculation compared to the wild type. The process outlined in this study which enhances glycerol consumption and cofactor regulation in an industrial yeast is a promising metabolic engineering strategy to increase ethanol production by reducing the formation of glycerol.

  10. A two-step protein quality control pathway for a misfolded DJ-1 variant in fission yeast

    DEFF Research Database (Denmark)

    Mathiassen, Søs Grønbæk; Larsen, Ida B.; Poulsen, Esben Guldahl

    2015-01-01

    A mutation, L166P, in the cytosolic protein, PARK7/DJ-1, causes protein misfolding and is linked to Parkinson disease. Here, we identify the fission yeast protein Sdj1 as the orthologue of DJ-1 and calculate by in silico saturation mutagenesis the effects of point mutants on its structural...... stability. We also map the degradation pathways for Sdj1-L169P, the fission yeast orthologue of the disease-causing DJ-1 L166P protein. Sdj1-L169P forms inclusions, which are enriched for the Hsp104 disaggregase. Hsp104 and Hsp70-type chaperones are required for efficient degradation of Sdj1-L169P...

  11. The step-wise pathway of septin hetero-octamer assembly in budding yeast.

    Science.gov (United States)

    Weems, Andrew; McMurray, Michael

    2017-05-25

    Septin proteins bind guanine nucleotides and form rod-shaped hetero-oligomers. Cells choose from a variety of available septins to assemble distinct hetero-oligomers, but the underlying mechanism was unknown. Using a new in vivo assay, we find that a stepwise assembly pathway produces the two species of budding yeast septin hetero-octamers: Cdc11/Shs1-Cdc12-Cdc3-Cdc10-Cdc10-Cdc3-Cdc12-Cdc11/Shs1. Rapid GTP hydrolysis by monomeric Cdc10 drives assembly of the core Cdc10 homodimer. The extended Cdc3 N terminus autoinhibits Cdc3 association with Cdc10 homodimers until prior Cdc3-Cdc12 interaction. Slow hydrolysis by monomeric Cdc12 and specific affinity of Cdc11 for transient Cdc12•GTP drive assembly of distinct trimers, Cdc11-Cdc12-Cdc3 or Shs1-Cdc12-Cdc3. Decreasing the cytosolic GTP:GDP ratio increases the incorporation of Shs1 vs Cdc11, which alters the curvature of filamentous septin rings. Our findings explain how GTP hydrolysis controls septin assembly, and uncover mechanisms by which cells construct defined septin complexes.

  12. Tolerant industrial yeast Saccharomyces cerevisiae posses a more robust cell wall integrity signaling pathway against 2-furaldehyde and 5-(hydroxymethyl)-2-furaldehyde

    Science.gov (United States)

    Cell wall integrity signaling pathway in Saccharomyces cerevisiae is a conserved function for detecting and responding to cell stress conditions but less understood for industrial yeast. We dissected gene expression dynamics for a tolerant industrial yeast strain NRRL Y-50049 in response to challeng...

  13. Endogenous ribosomal frameshift signals operate as mRNA destabilizing elements through at least two molecular pathways in yeast.

    Science.gov (United States)

    Belew, Ashton T; Advani, Vivek M; Dinman, Jonathan D

    2011-04-01

    Although first discovered in viruses, previous studies have identified operational -1 ribosomal frameshifting (-1 RF) signals in eukaryotic genomic sequences, and suggested a role in mRNA stability. Here, four yeast -1 RF signals are shown to promote significant mRNA destabilization through the nonsense mediated mRNA decay pathway (NMD), and genetic evidence is presented suggesting that they may also operate through the no-go decay pathway (NGD) as well. Yeast EST2 mRNA is highly unstable and contains up to five -1 RF signals. Ablation of the -1 RF signals or of NMD stabilizes this mRNA, and changes in -1 RF efficiency have opposing effects on the steady-state abundance of the EST2 mRNA. These results demonstrate that endogenous -1 RF signals function as mRNA destabilizing elements through at least two molecular pathways in yeast. Consistent with current evolutionary theory, phylogenetic analyses suggest that -1 RF signals are rapidly evolving cis-acting regulatory elements. Identification of high confidence -1 RF signals in ∼10% of genes in all eukaryotic genomes surveyed suggests that -1 RF is a broadly used post-transcriptional regulator of gene expression.

  14. The role of the Parkinson's disease gene PARK9 in essential cellular pathways and the manganese homeostasis network in yeast.

    Directory of Open Access Journals (Sweden)

    Alessandra Chesi

    Full Text Available YPK9 (Yeast PARK9; also known as YOR291W is a non-essential yeast gene predicted by sequence to encode a transmembrane P-type transport ATPase. However, its substrate specificity is unknown. Mutations in the human homolog of YPK9, ATP13A2/PARK9, have been linked to genetic forms of early onset parkinsonism. We previously described a strong genetic interaction between Ypk9 and another Parkinson's disease (PD protein α-synuclein in multiple model systems, and a role for Ypk9 in manganese detoxification in yeast. In humans, environmental exposure to toxic levels of manganese causes a syndrome similar to PD and is thus an environmental risk factor for the disease. How manganese contributes to neurodegeneration is poorly understood. Here we describe multiple genome-wide screens in yeast aimed at defining the cellular function of Ypk9 and the mechanisms by which it protects cells from manganese toxicity. In physiological conditions, we found that Ypk9 genetically interacts with essential genes involved in cellular trafficking and the cell cycle. Deletion of Ypk9 sensitizes yeast cells to exposure to excess manganese. Using a library of non-essential gene deletions, we screened for additional genes involved in tolerance to excess manganese exposure, discovering several novel pathways involved in manganese homeostasis. We defined the dependence of the deletion strain phenotypes in the presence of manganese on Ypk9, and found that Ypk9 deletion modifies the manganese tolerance of only a subset of strains. These results confirm a role for Ypk9 in manganese homeostasis and illuminates cellular pathways and biological processes in which Ypk9 likely functions.

  15. Quantitative elementary mode analysis of metabolic pathways: the example of yeast glycolysis

    Directory of Open Access Journals (Sweden)

    Kanehisa Minoru

    2006-04-01

    Full Text Available Abstract Background Elementary mode analysis of metabolic pathways has proven to be a valuable tool for assessing the properties and functions of biochemical systems. However, little comprehension of how individual elementary modes are used in real cellular states has been achieved so far. A quantitative measure of fluxes carried by individual elementary modes is of great help to identify dominant metabolic processes, and to understand how these processes are redistributed in biological cells in response to changes in environmental conditions, enzyme kinetics, or chemical concentrations. Results Selecting a valid decomposition of a flux distribution onto a set of elementary modes is not straightforward, since there is usually an infinite number of possible such decompositions. We first show that two recently introduced decompositions are very closely related and assign the same fluxes to reversible elementary modes. Then, we show how such decompositions can be used in combination with kinetic modelling to assess the effects of changes in enzyme kinetics on the usage of individual metabolic routes, and to analyse the range of attainable states in a metabolic system. This approach is illustrated by the example of yeast glycolysis. Our results indicate that only a small subset of the space of stoichiometrically feasible steady states is actually reached by the glycolysis system, even when large variation intervals are allowed for all kinetic parameters of the model. Among eight possible elementary modes, the standard glycolytic route remains dominant in all cases, and only one other elementary mode is able to gain significant flux values in steady state. Conclusion These results indicate that a combination of structural and kinetic modelling significantly constrains the range of possible behaviours of a metabolic system. All elementary modes are not equal contributors to physiological cellular states, and this approach may open a direction toward a

  16. Genome-Scale Analysis Reveals Sst2 as the Principal Regulator of Mating Pheromone Signaling in the Yeast Saccharomyces cerevisiae†

    Science.gov (United States)

    Chasse, Scott A.; Flanary, Paul; Parnell, Stephen C.; Hao, Nan; Cha, Jiyoung Y.; Siderovski, David P.; Dohlman, Henrik G.

    2006-01-01

    A common property of G protein-coupled receptors is that they become less responsive with prolonged stimulation. Regulators of G protein signaling (RGS proteins) are well known to accelerate G protein GTPase activity and do so by stabilizing the transition state conformation of the G protein α subunit. In the yeast Saccharomyces cerevisiae there are four RGS-homologous proteins (Sst2, Rgs2, Rax1, and Mdm1) and two Gα proteins (Gpa1 and Gpa2). We show that Sst2 is the only RGS protein that binds selectively to the transition state conformation of Gpa1. The other RGS proteins also bind Gpa1 and modulate pheromone signaling, but to a lesser extent and in a manner clearly distinct from Sst2. To identify other candidate pathway regulators, we compared pheromone responses in 4,349 gene deletion mutants representing nearly all nonessential genes in yeast. A number of mutants produced an increase (sst2, bar1, asc1, and ygl024w) or decrease (cla4) in pheromone sensitivity or resulted in pheromone-independent signaling (sst2, pbs2, gas1, and ygl024w). These findings suggest that Sst2 is the principal regulator of Gpa1-mediated signaling in vivo but that other proteins also contribute in distinct ways to pathway regulation. PMID:16467474

  17. Mga2 transcription factor regulates an oxygen-responsive lipid homeostasis pathway in fission yeast

    DEFF Research Database (Denmark)

    Burr, Risa; Stewart, Emerson V; Shao, Wei

    2016-01-01

    -binding protein (SREBP) transcription factors regulate lipid homeostasis. In mammals, SREBP-2 controls cholesterol biosynthesis, whereas SREBP-1 controls triacylglycerol and glycerophospholipid biosynthesis. In the fission yeast Schizosaccharomyces pombe, the SREBP-2 homolog Sre1 regulates sterol homeostasis....... In the absence of mga2, fission yeast exhibited growth defects under both normoxia and low oxygen conditions. Mga2 transcriptional targets were enriched for lipid metabolism genes, and mga2Δ cells showed disrupted triacylglycerol and glycerophospholipid homeostasis, most notably with an increase in fatty acid...

  18. Genomewide identification of pheromone-targeted transcription in fission yeast

    Directory of Open Access Journals (Sweden)

    Wright Anthony

    2006-11-01

    Full Text Available Abstract Background Fission yeast cells undergo sexual differentiation in response to nitrogen starvation. In this process haploid M and P cells first mate to form diploid zygotes, which then enter meiosis and sporulate. Prior to mating, M and P cells communicate with diffusible mating pheromones that activate a signal transduction pathway in the opposite cell type. The pheromone signalling orchestrates mating and is also required for entry into meiosis. Results Here we use DNA microarrays to identify genes that are induced by M-factor in P cells and by P-factor in M-cells. The use of a cyr1 genetic background allowed us to study pheromone signalling independently of nitrogen starvation. We identified a total of 163 genes that were consistently induced more than two-fold by pheromone stimulation. Gene disruption experiments demonstrated the involvement of newly discovered pheromone-induced genes in the differentiation process. We have mapped Gene Ontology (GO categories specifically associated with pheromone induction. A direct comparison of the M- and P-factor induced expression pattern allowed us to identify cell-type specific transcripts, including three new M-specific genes and one new P-specific gene. Conclusion We found that the pheromone response was very similar in M and P cells. Surprisingly, pheromone control extended to genes fulfilling their function well beyond the point of entry into meiosis, including numerous genes required for meiotic recombination. Our results suggest that the Ste11 transcription factor is responsible for the majority of pheromone-induced transcription. Finally, most cell-type specific genes now appear to be identified in fission yeast.

  19. Reconstructing the regulatory circuit of cell fate determination in yeast mating response.

    Science.gov (United States)

    Shao, Bin; Yuan, Haiyu; Zhang, Rongfei; Wang, Xuan; Zhang, Shuwen; Ouyang, Qi; Hao, Nan; Luo, Chunxiong

    2017-07-01

    Massive technological advances enabled high-throughput measurements of proteomic changes in biological processes. However, retrieving biological insights from large-scale protein dynamics data remains a challenging task. Here we used the mating differentiation in yeast Saccharomyces cerevisiae as a model and developed integrated experimental and computational approaches to analyze the proteomic dynamics during the process of cell fate determination. When exposed to a high dose of mating pheromone, the yeast cell undergoes growth arrest and forms a shmoo-like morphology; however, at intermediate doses, chemotropic elongated growth is initialized. To understand the gene regulatory networks that control this differentiation switch, we employed a high-throughput microfluidic imaging system that allows real-time and simultaneous measurements of cell growth and protein expression. Using kinetic modeling of protein dynamics, we classified the stimulus-dependent changes in protein abundance into two sources: global changes due to physiological alterations and gene-specific changes. A quantitative framework was proposed to decouple gene-specific regulatory modes from the growth-dependent global modulation of protein abundance. Based on the temporal patterns of gene-specific regulation, we established the network architectures underlying distinct cell fates using a reverse engineering method and uncovered the dose-dependent rewiring of gene regulatory network during mating differentiation. Furthermore, our results suggested a potential crosstalk between the pheromone response pathway and the target of rapamycin (TOR)-regulated ribosomal biogenesis pathway, which might underlie a cell differentiation switch in yeast mating response. In summary, our modeling approach addresses the distinct impacts of the global and gene-specific regulation on the control of protein dynamics and provides new insights into the mechanisms of cell fate determination. We anticipate that our

  20. A mitochondria-dependent pathway mediates the apoptosis of GSE-induced yeast.

    Directory of Open Access Journals (Sweden)

    Sishuo Cao

    Full Text Available Grapefruit seed extract (GSE, which has powerful anti-fungal activity, can induce apoptosis in S. cerevisiae. The yeast cells underwent apoptosis as determined by testing for apoptotic markers of DNA cleavage and typical chromatin condensation by Terminal Deoxynucleotidyl Transferase-mediated dUTP Nick End Labeling (TUNEL and 4,6'-diaminidino-2-phenylindole (DAPI staining and electron microscopy. The changes of ΔΨmt (mitochondrial transmembrane potential and ROS (reactive oxygen species indicated that the mitochondria took part in the apoptotic process. Changes in this process detected by metabonomics and proteomics revealed that the yeast cells tenaciously resisted adversity. Proteins related to redox, cellular structure, membrane, energy and DNA repair were significantly increased. In this study, the relative changes in the levels of proteins and metabolites showed the tenacious resistance of yeast cells. However, GSE induced apoptosis in the yeast cells by destruction of the mitochondrial 60 S ribosomal protein, L14-A, and prevented the conversion of pantothenic acid to coenzyme A (CoA. The relationship between the proteins and metabolites was analyzed by orthogonal projections to latent structures (OPLS. We found that the changes of the metabolites and the protein changes had relevant consistency.

  1. A mitochondria-dependent pathway mediates the apoptosis of GSE-induced yeast.

    Science.gov (United States)

    Cao, Sishuo; Xu, Wentao; Zhang, Nan; Wang, Yan; Luo, YunBo; He, Xiaoyun; Huang, Kunlun

    2012-01-01

    Grapefruit seed extract (GSE), which has powerful anti-fungal activity, can induce apoptosis in S. cerevisiae. The yeast cells underwent apoptosis as determined by testing for apoptotic markers of DNA cleavage and typical chromatin condensation by Terminal Deoxynucleotidyl Transferase-mediated dUTP Nick End Labeling (TUNEL) and 4,6'-diaminidino-2-phenylindole (DAPI) staining and electron microscopy. The changes of ΔΨmt (mitochondrial transmembrane potential) and ROS (reactive oxygen species) indicated that the mitochondria took part in the apoptotic process. Changes in this process detected by metabonomics and proteomics revealed that the yeast cells tenaciously resisted adversity. Proteins related to redox, cellular structure, membrane, energy and DNA repair were significantly increased. In this study, the relative changes in the levels of proteins and metabolites showed the tenacious resistance of yeast cells. However, GSE induced apoptosis in the yeast cells by destruction of the mitochondrial 60 S ribosomal protein, L14-A, and prevented the conversion of pantothenic acid to coenzyme A (CoA). The relationship between the proteins and metabolites was analyzed by orthogonal projections to latent structures (OPLS). We found that the changes of the metabolites and the protein changes had relevant consistency.

  2. A Mitochondria-Dependent Pathway Mediates the Apoptosis of GSE-Induced Yeast

    OpenAIRE

    Cao, Sishuo; Xu, Wentao; Zhang, Nan; Wang, Yan; Luo, YunBo; He, Xiaoyun; Huang, Kunlun

    2012-01-01

    Grapefruit seed extract (GSE), which has powerful anti-fungal activity, can induce apoptosis in S. cerevisiae. The yeast cells underwent apoptosis as determined by testing for apoptotic markers of DNA cleavage and typical chromatin condensation by Terminal Deoxynucleotidyl Transferase-mediated dUTP Nick End Labeling (TUNEL) and 4,6'-diaminidino-2-phenylindole (DAPI) staining and electron microscopy. The changes of ΔΨmt (mitochondrial transmembrane potential) and ROS (reactive oxygen species) ...

  3. A Western Blot-based Investigation of the Yeast Secretory Pathway Designed for an Intermediate-Level Undergraduate Cell Biology Laboratory

    Science.gov (United States)

    Hood-DeGrenier, Jennifer K.

    2008-01-01

    The movement of newly synthesized proteins through the endomembrane system of eukaryotic cells, often referred to generally as the secretory pathway, is a topic covered in most intermediate-level undergraduate cell biology courses. An article previously published in this journal described a laboratory exercise in which yeast mutants defective in…

  4. Influence of different yeast cell wall preparations and their components on performance and immune and metabolic pathways in Clostridium perfringens-challenged broiler chicks

    Science.gov (United States)

    A study was conducted to evaluate the influence of purification of yeast cell wall (YCW) preparations on broiler performance, and immunogenic and metabolic pathways under microbial challenge. A total of 240 day-of-hatch chicks were distributed among two battery brooder units (48 pens; 5 birds/pen; ...

  5. Determining Antifungal Target Sites in the Sterol Pathway of the Yeast Candida and Saccharomyces

    National Research Council Canada - National Science Library

    Bard, Martin

    1998-01-01

    ... as in topical infections which lead to significant losses in work-place productivity. The work reported here seeks to identify new target sites in the sterol biosynthetic pathway against which new antifungal compounds might be developed...

  6. Yeast glucose pathways converge on the transcriptional regulation of trehalose biosynthesis

    Directory of Open Access Journals (Sweden)

    Apweiler Eva

    2012-06-01

    Full Text Available Abstract Background Cellular glucose availability is crucial for the functioning of most biological processes. Our understanding of the glucose regulatory system has been greatly advanced by studying the model organism Saccharomyces cerevisiae, but many aspects of this system remain elusive. To understand the organisation of the glucose regulatory system, we analysed 91 deletion mutants of the different glucose signalling and metabolic pathways in Saccharomyces cerevisiae using DNA microarrays. Results In general, the mutations do not induce pathway-specific transcriptional responses. Instead, one main transcriptional response is discerned, which varies in direction to mimic either a high or a low glucose response. Detailed analysis uncovers established and new relationships within and between individual pathways and their members. In contrast to signalling components, metabolic components of the glucose regulatory system are transcriptionally more frequently affected. A new network approach is applied that exposes the hierarchical organisation of the glucose regulatory system. Conclusions The tight interconnection between the different pathways of the glucose regulatory system is reflected by the main transcriptional response observed. Tps2 and Tsl1, two enzymes involved in the biosynthesis of the storage carbohydrate trehalose, are predicted to be the most downstream transcriptional components. Epistasis analysis of tps2Δ double mutants supports this prediction. Although based on transcriptional changes only, these results suggest that all changes in perceived glucose levels ultimately lead to a shift in trehalose biosynthesis.

  7. The dectin-1/inflammasome pathway is responsible for the induction of protective T-helper 17 responses that discriminate between yeasts and hyphae of Candida albicans.

    Science.gov (United States)

    Cheng, Shih-Chin; van de Veerdonk, Frank L; Lenardon, Megan; Stoffels, Monique; Plantinga, Theo; Smeekens, Sanne; Rizzetto, Lisa; Mukaremera, Liliane; Preechasuth, Kanya; Cavalieri, Duccio; Kanneganti, Thirumala Devi; van der Meer, Jos W M; Kullberg, Bart Jan; Joosten, Leo A B; Gow, Neil A R; Netea, Mihai G

    2011-08-01

    In the mucosa, the immune pathways discriminating between colonizing and invasive Candida, thus inducing tolerance or inflammation, are poorly understood. Th17 responses induced by Candida albicans hyphae are central for the activation of mucosal antifungal immunity. An essential step for the discrimination between yeasts and hyphae and induction of Th17 responses is the activation of the inflammasome by C. albicans hyphae and the subsequent release of active IL-1β in macrophages. Inflammasome activation in macrophages results from differences in cell-wall architecture between yeasts and hyphae and is partly mediated by the dectin-1/Syk pathway. These results define the dectin-1/inflammasome pathway as the mechanism that enables the host immune system to mount a protective Th17 response and distinguish between colonization and tissue invasion by C. albicans.

  8. Expression of three topologically distinct membrane proteins elicits unique stress response pathways in the yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    Buck, Teresa M; Jordan, Rick; Lyons-Weiler, James; Adelman, Joshua L; Needham, Patrick G; Kleyman, Thomas R; Brodsky, Jeffrey L

    2015-06-01

    Misfolded membrane proteins are retained in the endoplasmic reticulum (ER) and are subject to ER-associated degradation, which clears the secretory pathway of potentially toxic species. While the transcriptional response to environmental stressors has been extensively studied, limited data exist describing the cellular response to misfolded membrane proteins. To this end, we expressed and then compared the transcriptional profiles elicited by the synthesis of three ER retained, misfolded ion channels: The α-subunit of the epithelial sodium channel, ENaC, the cystic fibrosis transmembrane conductance regulator, CFTR, and an inwardly rectifying potassium channel, Kir2.1, which vary in their mass, membrane topologies, and quaternary structures. To examine transcriptional profiles in a null background, the proteins were expressed in yeast, which was previously used to examine the degradation requirements for each substrate. Surprisingly, the proteins failed to induce a canonical unfolded protein response or heat shock response, although messages encoding several cytosolic and ER lumenal protein folding factors rose when αENaC or CFTR was expressed. In contrast, the levels of these genes were unaltered by Kir2.1 expression; instead, the yeast iron regulon was activated. Nevertheless, a significant number of genes that respond to various environmental stressors were upregulated by all three substrates, and compared with previous microarray data we deduced the existence of a group of genes that reflect a novel misfolded membrane protein response. These data indicate that aberrant proteins in the ER elicit profound yet unique cellular responses. Copyright © 2015 the American Physiological Society.

  9. Enhancement of the proline and nitric oxide synthetic pathway improves fermentation ability under multiple baking-associated stress conditions in industrial baker's yeast

    Directory of Open Access Journals (Sweden)

    Sasano Yu

    2012-04-01

    generation and that increased NO plays an important role in baking-associated stress tolerance. Conclusions In this work, we clarified the importance of Put1- and Mpr1-mediated NO generation from proline to the baking-associated stress tolerance in industrial baker's yeast. We also demonstrated that baker's yeast that enhances the proline and NO synthetic pathway by expressing the Pro1-I150T and Mpr1-F65L variants showed improved fermentation ability under multiple baking-associated stress conditions. From a biotechnological perspective, the enhancement of proline and NO synthesis could be promising for breeding novel baker's yeast strains.

  10. Enhancement of the proline and nitric oxide synthetic pathway improves fermentation ability under multiple baking-associated stress conditions in industrial baker's yeast.

    Science.gov (United States)

    Sasano, Yu; Haitani, Yutaka; Hashida, Keisuke; Ohtsu, Iwao; Shima, Jun; Takagi, Hiroshi

    2012-04-01

    role in baking-associated stress tolerance. In this work, we clarified the importance of Put1- and Mpr1-mediated NO generation from proline to the baking-associated stress tolerance in industrial baker's yeast. We also demonstrated that baker's yeast that enhances the proline and NO synthetic pathway by expressing the Pro1-I150T and Mpr1-F65L variants showed improved fermentation ability under multiple baking-associated stress conditions. From a biotechnological perspective, the enhancement of proline and NO synthesis could be promising for breeding novel baker's yeast strains.

  11. Enhancement of the proline and nitric oxide synthetic pathway improves fermentation ability under multiple baking-associated stress conditions in industrial baker's yeast

    Science.gov (United States)

    2012-01-01

    plays an important role in baking-associated stress tolerance. Conclusions In this work, we clarified the importance of Put1- and Mpr1-mediated NO generation from proline to the baking-associated stress tolerance in industrial baker's yeast. We also demonstrated that baker's yeast that enhances the proline and NO synthetic pathway by expressing the Pro1-I150T and Mpr1-F65L variants showed improved fermentation ability under multiple baking-associated stress conditions. From a biotechnological perspective, the enhancement of proline and NO synthesis could be promising for breeding novel baker's yeast strains. PMID:22462683

  12. Assembly and Multiplex Genome Integration of Metabolic Pathways in Yeast Using CasEMBLR

    DEFF Research Database (Denmark)

    Jakočiūnas, Tadas; Jensen, Emil D.; Jensen, Michael Krogh

    2018-01-01

    and marker-free integration of the carotenoid pathway from 15 exogenously supplied DNA parts into three targeted genomic loci. As a second proof-of-principle, a total of ten DNA parts were assembled and integrated in two genomic loci to construct a tyrosine production strain, and at the same time knocking......Genome integration is a vital step for implementing large biochemical pathways to build a stable microbial cell factory. Although traditional strain construction strategies are well established for the model organism Saccharomyces cerevisiae, recent advances in CRISPR/Cas9-mediated genome...... engineering allow much higher throughput and robustness in terms of strain construction. In this chapter, we describe CasEMBLR, a highly efficient and marker-free genome engineering method for one-step integration of in vivo assembled expression cassettes in multiple genomic sites simultaneously. Cas...

  13. The sandfly Lutzomyia longipalpis LL5 embryonic cell line has active Toll and Imd pathways and shows immune responses to bacteria, yeast and Leishmania.

    Science.gov (United States)

    Tinoco-Nunes, Bruno; Telleria, Erich Loza; da Silva-Neves, Monique; Marques, Christiane; Azevedo-Brito, Daisy Aline; Pitaluga, André Nóbrega; Traub-Csekö, Yara Maria

    2016-04-20

    Lutzomyia longipalpis is the main vector of visceral leishmaniasis in Latin America. Sandfly immune responses are poorly understood. In previous work we showed that these vector insects respond to bacterial infections by modulating a defensin gene expression and activate the Imd pathway in response to Leishmania infection. Aspects of innate immune pathways in insects (including mosquito vectors of human diseases) have been revealed by studying insect cell lines, and we have previously demonstrated antiviral responses in the L. longipalpis embryonic cell line LL5. The expression patterns of antimicrobial peptides (AMPs) and transcription factors were evaluated after silencing the repressors of the Toll pathway (cactus) and Imd pathway (caspar). AMPs and transcription factor expression patterns were also evaluated after challenge with heat-killed bacteria, heat-killed yeast, or live Leishmania. These studies showed that LL5 cells have active Toll and Imd pathways, since they displayed an increased expression of AMP genes following silencing of the repressors cactus and caspar, respectively. These pathways were also activated by challenges with bacteria, yeast and Leishmania infantum chagasi. We demonstrated that L. longipalpis LL5 embryonic cells respond to immune stimuli and are therefore a good model to study the immunological pathways of this important vector of leishmaniasis.

  14. Low doses of a neonicotinoid insecticide modify pheromone response thresholds of central but not peripheral olfactory neurons in a pest insect.

    Science.gov (United States)

    Rabhi, Kaouther K; Deisig, Nina; Demondion, Elodie; Le Corre, Julie; Robert, Guillaume; Tricoire-Leignel, Hélène; Lucas, Philippe; Gadenne, Christophe; Anton, Sylvia

    2016-02-10

    Insect pest management relies mainly on neurotoxic insecticides, including neonicotinoids, leaving residues in the environment. There is now evidence that low doses of insecticides can have positive effects on pest insects by enhancing various life traits. Because pest insects often rely on sex pheromones for reproduction, and olfactory synaptic transmission is cholinergic, neonicotinoid residues could modify chemical communication. We recently showed that treatments with different sublethal doses of clothianidin could either enhance or decrease behavioural sex pheromone responses in the male moth, Agrotis ipsilon. We investigated now effects of the behaviourally active clothianidin doses on the sensitivity of the peripheral and central olfactory system. We show with extracellular recordings that both tested clothianidin doses do not influence pheromone responses in olfactory receptor neurons. Similarly, in vivo optical imaging does not reveal any changes in glomerular response intensities to the sex pheromone after clothianidin treatments. The sensitivity of intracellularly recorded antennal lobe output neurons, however, is upregulated by a lethal dose 20 times and downregulated by a dose 10 times lower than the lethal dose 0. This correlates with the changes of behavioural responses after clothianidin treatment and suggests the antennal lobe as neural substrate involved in clothianidin-induced behavioural changes. © 2016 The Author(s).

  15. Assembly and Multiplex Genome Integration of Metabolic Pathways in Yeast Using CasEMBLR.

    Science.gov (United States)

    Jakočiūnas, Tadas; Jensen, Emil D; Jensen, Michael K; Keasling, Jay D

    2018-01-01

    Genome integration is a vital step for implementing large biochemical pathways to build a stable microbial cell factory. Although traditional strain construction strategies are well established for the model organism Saccharomyces cerevisiae, recent advances in CRISPR/Cas9-mediated genome engineering allow much higher throughput and robustness in terms of strain construction. In this chapter, we describe CasEMBLR, a highly efficient and marker-free genome engineering method for one-step integration of in vivo assembled expression cassettes in multiple genomic sites simultaneously. CasEMBLR capitalizes on the CRISPR/Cas9 technology to generate double-strand breaks in genomic loci, thus prompting native homologous recombination (HR) machinery to integrate exogenously derived homology templates. As proof-of-principle for microbial cell factory development, CasEMBLR was used for one-step assembly and marker-free integration of the carotenoid pathway from 15 exogenously supplied DNA parts into three targeted genomic loci. As a second proof-of-principle, a total of ten DNA parts were assembled and integrated in two genomic loci to construct a tyrosine production strain, and at the same time knocking out two genes. This new method complements and improves the field of genome engineering in S. cerevisiae by providing a more flexible platform for rapid and precise strain building.

  16. ATP regeneration with enzymes of the alcohol fermentation pathway and kinases of yeast and its computer simulation

    Energy Technology Data Exchange (ETDEWEB)

    Asada, M; Shirai, Y; Nakanishi, K; Matsuno, R; Kimura, A; Kamikubo, T

    1981-08-01

    Enzymes of the alcohol fermentation pathway, adenosine kinase and adenylate kinase were extracted by incubating acetone-dried yeast cells with a simple reaction medium containing glucose, and subjected to gel filtration to remove the intermediates of alcohol fermentation formed during incubation. By using the enzyme systems as catalysts and glucose as an energy source, ATP was regenerated from adenosine. A minimum concentration of fructose 1,6-bisphosphate (FBP) of 7 mM or of ATP of 10 mM was necessary to initiate the alcohol fermentation; and concentrations of nucleotides changed abruptly with reaction time. These nonlinear phenomena might be due to action of FBPase and/or ATPase as well as the complex multienzyme systems. To understand the experimentally observed phenomena, a mathematical model of the reaction system was proposed which takes into account ATP regeneration. The calculated time-dependent concentrations of glucose, FBP, adenosine and nucleotides were in agreement with experimental values qualitatively as well as quantitatively. Moreover, the nonlinear phenomena, that is, the existence of threshold concentrations of FBP and ATP below which the reaction can not proceed and the steep changes of nucleotide concentrations were also accounted for. These results indicate that the model was quite suitable for this reaction system and useful for predicting the experimental results.

  17. Identification of a Sgo2-Dependent but Mad2-Independent Pathway Controlling Anaphase Onset in Fission Yeast

    Directory of Open Access Journals (Sweden)

    John C. Meadows

    2017-02-01

    Full Text Available The onset of anaphase is triggered by activation of the anaphase-promoting complex/cyclosome (APC/C following silencing of the spindle assembly checkpoint (SAC. APC/C triggers ubiquitination of Securin and Cyclin B, which leads to loss of sister chromatid cohesion and inactivation of Cyclin B/Cdk1, respectively. This promotes relocalization of Aurora B kinase and other components of the chromosome passenger complex (CPC from centromeres to the spindle midzone. In fission yeast, this is mediated by Clp1 phosphatase-dependent interaction of CPC with Klp9/MKLP2 (kinesin-6. When this interaction is disrupted, kinetochores bi-orient normally, but APC/C activation is delayed via a mechanism that requires Sgo2 and some (Bub1, Mph1/Mps1, and Mad3, but not all (Mad1 and Mad2, components of the SAC and the first, but not second, lysine, glutamic acid, glutamine (KEN box in Mad3. These data indicate that interaction of CPC with Klp9 terminates a Sgo2-dependent, but Mad2-independent, APC/C-inhibitory pathway that is distinct from the canonical SAC.

  18. Nuclear fusion during yeast mating occurs by a three-step pathway.

    Science.gov (United States)

    Melloy, Patricia; Shen, Shu; White, Erin; McIntosh, J Richard; Rose, Mark D

    2007-11-19

    In Saccharomyces cerevisiae, mating culminates in nuclear fusion to produce a diploid zygote. Two models for nuclear fusion have been proposed: a one-step model in which the outer and inner nuclear membranes and the spindle pole bodies (SPBs) fuse simultaneously and a three-step model in which the three events occur separately. To differentiate between these models, we used electron tomography and time-lapse light microscopy of early stage wild-type zygotes. We observe two distinct SPBs in approximately 80% of zygotes that contain fused nuclei, whereas we only see fused or partially fused SPBs in zygotes in which the site of nuclear envelope (NE) fusion is already dilated. This demonstrates that SPB fusion occurs after NE fusion. Time-lapse microscopy of zygotes containing fluorescent protein tags that localize to either the NE lumen or the nucleoplasm demonstrates that outer membrane fusion precedes inner membrane fusion. We conclude that nuclear fusion occurs by a three-step pathway.

  19. Screening the yeast genome for energetic metabolism pathways involved in a phenotypic response to the anti-cancer agent 3-bromopyruvate.

    Science.gov (United States)

    Lis, Paweł; Jurkiewicz, Paweł; Cal-Bąkowska, Magdalena; Ko, Young H; Pedersen, Peter L; Goffeau, Andre; Ułaszewski, Stanisław

    2016-03-01

    In this study the detailed characteristic of the anti-cancer agent 3-bromopyruvate (3-BP) activity in the yeast Saccharomyces cerevisiae model is described, with the emphasis on its influence on energetic metabolism of the cell. It shows that 3-BP toxicity in yeast is strain-dependent and influenced by the glucose-repression system. Its toxic effect is mainly due to the rapid depletion of intracellular ATP. Moreover, lack of the Whi2p phosphatase results in strongly increased sensitivity of yeast cells to 3-BP, possibly due to the non-functional system of mitophagy of damaged mitochondria through the Ras-cAMP-PKA pathway. Single deletions of genes encoding glycolytic enzymes, the TCA cycle enzymes and mitochondrial carriers result in multiple effects after 3-BP treatment. However, it can be concluded that activity of the pentose phosphate pathway is necessary to prevent the toxicity of 3-BP, probably due to the fact that large amounts of NADPH are produced by this pathway, ensuring the reducing force needed for glutathione reduction, crucial to cope with the oxidative stress. Moreover, single deletions of genes encoding the TCA cycle enzymes and mitochondrial carriers generally cause sensitivity to 3-BP, while totally inactive mitochondrial respiration in the rho0 mutant resulted in increased resistance to 3-BP.

  20. Targeting of SUMO substrates to a Cdc48-Ufd1-Npl4 segregase and STUbL pathway in fission yeast

    DEFF Research Database (Denmark)

    Køhler, Julie Bonne; Tammsalu, Triin; Jørgensen, Maria Louise Mønster

    2015-01-01

    48/p97-Ufd1-Npl4 facilitates this process. However, the extent to which the two pathways overlap, and how substrates are selected, remains unknown. Here we address these questions in fission yeast through proteome-wide analyses of SUMO modification sites. We identify over a thousand sumoylated...... lysines in a total of 468 proteins and quantify changes occurring in the SUMO modification status when the STUbL or Ufd1 pathways are compromised by mutations. The data suggest the coordinated processing of several classes of SUMO conjugates, many dynamically associated with centromeres or telomeres...

  1. The role of the RACK1 ortholog Cpc2p in modulating pheromone-induced cell cycle arrest in fission yeast.

    Directory of Open Access Journals (Sweden)

    Magdalena Mos

    Full Text Available The detection and amplification of extracellular signals requires the involvement of multiple protein components. In mammalian cells the receptor of activated C kinase (RACK1 is an important scaffolding protein for signal transduction networks. Further, it also performs a critical function in regulating the cell cycle by modulating the G1/S transition. Many eukaryotic cells express RACK1 orthologs, with one example being Cpc2p in the fission yeast Schizosaccharomyces pombe. In contrast to RACK1, Cpc2p has been described to positively regulate, at the ribosomal level, cells entry into M phase. In addition, Cpc2p controls the stress response pathways through an interaction with Msa2p, and sexual development by modulating Ran1p/Pat1p. Here we describe investigations into the role, which Cpc2p performs in controlling the G protein-mediated mating response pathway. Despite structural similarity to Gβ-like subunits, Cpc2p appears not to function at the G protein level. However, upon pheromone stimulation, cells overexpressing Cpc2p display substantial cell morphology defects, disorientation of septum formation and a significantly protracted G1 arrest. Cpc2p has the potential to function at multiple positions within the pheromone response pathway. We provide a mechanistic interpretation of this novel data by linking Cpc2p function, during the mating response, with its previous described interactions with Ran1p/Pat1p. We suggest that overexpressing Cpc2p prolongs the stimulated state of pheromone-induced cells by increasing ste11 gene expression. These data indicate that Cpc2p regulates the pheromone-induced cell cycle arrest in fission yeast by delaying cells entry into S phase.

  2. Harnessing Yeast Peroxisomes for Biosynthesis of Fatty-Acid-Derived Biofuels and Chemicals with Relieved Side-Pathway Competition

    DEFF Research Database (Denmark)

    Zhou, Yongjin J.; Buijs, Nicolaas A; Zhu, Zhiwei

    2016-01-01

    Establishing efficient synthetic pathways for microbial production of biochemicals is often hampered by competing pathways and/or insufficient precursor supply. Compartmentalization in cellular organelles can isolate synthetic pathways from competing pathways, and provide a compact and suitable e...

  3. MMS2, Encoding a ubiquitin-conjugating-enzyme-like protein, is a member of the yeast error-free postreplication repair pathway

    International Nuclear Information System (INIS)

    Broomfield, S.; Chow, B.L.; Xiao, W.

    1998-01-01

    Among the three Saccharomyces cerevisiae DNA repair epistasis groups, the RAD6 group is the most complicated and least characterized, primarily because it consists of two separate repair pathways: an error-free postreplication repair pathway, and a mutagenesis pathway. The rad6 and rad18 mutants are defective in both pathways, and the rev3 mutant affects only the mutagenesis pathway, but a yeast gene that is involved only in error-free postreplication repair has not been reported. We cloned the MMS2 gene from a yeast genomic library by functional complementation of the mms2-1 mutant [Prakash, L. and Prakash, S. (1977) Genetics 86, 33-55]. MMS2 encodes a 137-amino acid, 15.2-kDa protein with significant sequence homology to a conserved family of ubiquitin-conjugating (Ubc) proteins. However, Mms2 does not appear to possess Ubc activity. Genetic analyses indicate that the mms2 mutation is hypostatic to rad6 and rad18 but is synergistic with the rev3 mutation, and the mms2 mutant is proficient in UV-induced mutagenesis. These phenotypes are reminiscent of a pol30-46 mutant known to be impaired in postreplication repair. The mms2 mutant also displayed a REV3-dependent mutator phenotype, strongly suggesting that the MMS2 gene functions in the error-free postreplication repair pathway, parallel to the REV3 mutagenesis pathway. Furthermore, with respect to UV sensitivity, mms2 was found to be hypostatic to the rad6 delta 1-9 mutation, which results in the absence of the first nine amino acids of Rad6. On the basis of these collective results, we propose that the mms2 null mutation and two other allele-specific mutations, rad6 delta 1-9 and pol30-46, define the error-free mode of DNA postreplication repair, and that these mutations may enhance both spontaneous and DNA damage-induced mutagenesis

  4. Activation of the Cph1-dependent MAP kinase signaling pathway induces white-opaque switching in Candida albicans.

    Directory of Open Access Journals (Sweden)

    Bernardo Ramírez-Zavala

    Full Text Available Depending on the environmental conditions, the pathogenic yeast Candida albicans can undergo different developmental programs, which are controlled by dedicated transcription factors and upstream signaling pathways. C. albicans strains that are homozygous at the mating type locus can switch from the normal yeast form (white to an elongated cell type (opaque, which is the mating-competent form of this fungus. Both white and opaque cells use the Ste11-Hst7-Cek1/Cek2 MAP kinase signaling pathway to react to the presence of mating pheromone. However, while opaque cells employ the transcription factor Cph1 to induce the mating response, white cells recruit a different downstream transcription factor, Tec1, to promote the formation of a biofilm that facilitates mating of opaque cells in the population. The switch from the white to the opaque cell form is itself induced by environmental signals that result in the upregulation of the transcription factor Wor1, the master regulator of white-opaque switching. To get insight into the upstream signaling pathways controlling the switch, we expressed all C. albicans protein kinases from a tetracycline-inducible promoter in a switching-competent strain. Screening of this library of strains showed that a hyperactive form of Ste11 lacking its N-terminal domain (Ste11(ΔN467 efficiently stimulated white cells to switch to the opaque phase, a behavior that did not occur in response to pheromone. Ste11(ΔN467-induced switching specifically required the downstream MAP kinase Cek1 and its target transcription factor Cph1, but not Cek2 and Tec1, and forced expression of Cph1 also promoted white-opaque switching in a Wor1-dependent manner. Therefore, depending on the activation mechanism, components of the pheromone-responsive MAP kinase pathway can be reconnected to stimulate an alternative developmental program, switching of white cells to the mating-competent opaque phase.

  5. Synergistic interactions between RAD5, RAD16, and RAD54, three partially homologous yeast DNA repair genes each in a different repair pathway

    International Nuclear Information System (INIS)

    Glassner, B.J.; Mortimer, R.K.

    1994-01-01

    Considerable homology has recently been noted between the proteins encoded by the RAD5, RAD16 and RAD54 genes of Saccharomyces cerevisiae. These genes are members of the RAD6, RAD3 and RAD50 epistasis groups, respectively, which correspond to the three major DNA repair pathways in yeast. These proteins also share homology with other eucaryotic proteins, including those encoded by SNF2 and MO1 of yeast, brahma and lodestar of Drosophila and the human ERCC6 gene. The homology shares features with known helicases, suggesting a newly identified helicase subfamily. We have constructed a series of congenic single-, double- and triple-deletion mutants involving RAD5, RAD16 and RAD54 to examine the interactions between these genes. Each deletion mutation alone has only a moderate effect on survival after exposure to UV radiation. Each pairwise-double mutant exhibits marked synergism. The triple-deletion mutant displays further synergism. These results confirm the assignment of the RAD54 gene to the RAD50 epistasis group and suggest that the RAD16 gene plays a larger role in DNA repair after exposure to UV radiation than has been suggested previously. Additionally, the proteins encoded by RAD5, RAD16, and RAD54 may compete for the same substrate after damage induced by UV radiation, possibly at an early step in their respective pathways. 49 refs., 6 figs., 2 tabs

  6. The resistance of the yeast Saccharomyces cerevisiae to the biocide polyhexamethylene biguanide: involvement of cell wall integrity pathway and emerging role for YAP1

    Directory of Open Access Journals (Sweden)

    de Morais Marcos A

    2011-08-01

    Full Text Available Abstract Background Polyhexamethylene biguanide (PHMB is an antiseptic polymer that is mainly used for cleaning hospitals and pools and combating Acantamoeba infection. Its fungicide activity was recently shown by its lethal effect on yeasts that contaminate the industrial ethanol process, and on the PE-2 strain of Saccharomyces cerevisiae, one of the main fermenting yeasts in Brazil. This pointed to the need to know the molecular mechanism that lay behind the cell resistance to this compound. In this study, we examined the factors involved in PHMB-cell interaction and the mechanisms that respond to the damage caused by this interaction. To achieve this, two research strategies were employed: the expression of some genes by RT-qPCR and the analysis of mutant strains. Results Cell Wall integrity (CWI genes were induced in the PHMB-resistant Saccharomyces cerevisiae strain JP-1, although they are poorly expressed in the PHMB-sensitive Saccharomyces cerevisiae PE2 strain. This suggested that PHMB damages the glucan structure on the yeast cell wall. It was also confirmed by the observed sensitivity of the yeast deletion strains, Δslg1, Δrom2, Δmkk2, Δslt2, Δknr4, Δswi4 and Δswi4, which showed that the protein kinase C (PKC regulatory mechanism is involved in the response and resistance to PHMB. The sensitivity of the Δhog1 mutant was also observed. Furthermore, the cytotoxicity assay and gene expression analysis showed that the part played by YAP1 and CTT1 genes in cell resistance to PHMB is unrelated to oxidative stress response. Thus, we suggested that Yap1p can play a role in cell wall maintenance by controlling the expression of the CWI genes. Conclusion The PHMB treatment of the yeast cells activates the PKC1/Slt2 (CWI pathway. In addition, it is suggested that HOG1 and YAP1 can play a role in the regulation of CWI genes.

  7. The Post-mating Switch in the Pheromone Response of Nasonia Females Is Mediated by Dopamine and Can Be Reversed by Appetitive Learning

    Directory of Open Access Journals (Sweden)

    Maria Lenschow

    2018-01-01

    Full Text Available The olfactory sense is of crucial importance for animals, but their response to chemical stimuli is plastic and depends on their physiological state and prior experience. In many insect species, mating status influences the response to sex pheromones, but the underlying neuromodulatory mechanisms are poorly understood. After mating, females of the parasitic wasp Nasonia vitripennis are no longer attracted to the male sex pheromone. Here we show that this post-mating behavioral switch is mediated by dopamine (DA. Females fed a DA-receptor antagonist prior to mating maintained their attraction to the male pheromone after mating while virgin females injected with DA became unresponsive. However, the switch is reversible as mated females regained their pheromone preference after appetitive learning. Feeding mated N. vitripennis females with antagonists of either octopamine- (OA or DA-receptors prevented relearning of the pheromone preference suggesting that both receptors are involved in appetitive learning. Moreover, DA injection into mated females was sufficient to mimic the oviposition reward during odor conditioning with the male pheromone. Our data indicate that DA plays a key role in the plastic pheromone response of N. vitripennis females and reveal some striking parallels between insects and mammals in the neuromodulatory mechanisms underlying olfactory plasticity.

  8. Coordinated regulation by two VPS9 domain-containing guanine nucleotide exchange factors in small GTPase Rab5 signaling pathways in fission yeast

    International Nuclear Information System (INIS)

    Tsukamoto, Yuta; Kagiwada, Satoshi; Shimazu, Sayuri; Takegawa, Kaoru; Noguchi, Tetsuko; Miyamoto, Masaaki

    2015-01-01

    The small GTPase Rab5 is reported to regulate various cellular functions, such as vesicular transport and endocytosis. VPS9 domain-containing proteins are thought to activate Rab5(s) by their guanine-nucleotide exchange activities. Numerous VPS9 proteins have been identified and are structurally conserved from yeast to mammalian cells. However, the functional relationships among VPS9 proteins in cells remain unclear. Only one Rab5 and two VPS9 proteins were identified in the Schizosaccharomyces pombe genome. Here, we examined the cellular function of two VPS9 proteins and the relationship between these proteins in cellular functions. Vps901-GFP and Vps902-GFP exhibited dotted signals in vegetative and differentiated cells. vps901 deletion mutant (Δvps901) cells exhibited a phenotype deficient in the mating process and responses to high concentrations of ions, such as calcium and metals, and Δvps901Δvps902 double mutant cells exhibited round cell shapes similar to ypt5-909 (Rab5 mutant allele) cells. Deletion of both vps901 and vps902 genes completely abolished the mating process and responses to various stresses. A lack of vacuole formation and aberrant inner cell membrane structures were also observed in Δvps901Δvps902 cells by electron microscopy. These data strongly suggest that Vps901 and Vps902 are cooperatively involved in the regulation of cellular functions, such as cell morphology, sexual development, response to ion stresses, and vacuole formation, via Rab5 signaling pathways in fission yeast cells. - Highlights: • Roles of Rab5 activator VPS9 proteins in cellular functions. • Cooperation between VPS9 proteins in Rab5 signaling pathway. • Roles of each VPS9 protein in Rab5 signaling pathway are discussed

  9. Coordinated regulation by two VPS9 domain-containing guanine nucleotide exchange factors in small GTPase Rab5 signaling pathways in fission yeast

    Energy Technology Data Exchange (ETDEWEB)

    Tsukamoto, Yuta [Department of Biology, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501 (Japan); Kagiwada, Satoshi [Department of Biological Sciences, Faculty of Science, Nara Women' s University, Kitauoyanishi-machi, Nara 630-8506 (Japan); Shimazu, Sayuri [Center for Supports to Research and Education Activities, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501 (Japan); Takegawa, Kaoru [Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581 (Japan); Noguchi, Tetsuko [Department of Biological Sciences, Faculty of Science, Nara Women' s University, Kitauoyanishi-machi, Nara 630-8506 (Japan); Miyamoto, Masaaki, E-mail: miya@kobe-u.ac.jp [Department of Biology, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501 (Japan); Center for Supports to Research and Education Activities, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501 (Japan)

    2015-03-20

    The small GTPase Rab5 is reported to regulate various cellular functions, such as vesicular transport and endocytosis. VPS9 domain-containing proteins are thought to activate Rab5(s) by their guanine-nucleotide exchange activities. Numerous VPS9 proteins have been identified and are structurally conserved from yeast to mammalian cells. However, the functional relationships among VPS9 proteins in cells remain unclear. Only one Rab5 and two VPS9 proteins were identified in the Schizosaccharomyces pombe genome. Here, we examined the cellular function of two VPS9 proteins and the relationship between these proteins in cellular functions. Vps901-GFP and Vps902-GFP exhibited dotted signals in vegetative and differentiated cells. vps901 deletion mutant (Δvps901) cells exhibited a phenotype deficient in the mating process and responses to high concentrations of ions, such as calcium and metals, and Δvps901Δvps902 double mutant cells exhibited round cell shapes similar to ypt5-909 (Rab5 mutant allele) cells. Deletion of both vps901 and vps902 genes completely abolished the mating process and responses to various stresses. A lack of vacuole formation and aberrant inner cell membrane structures were also observed in Δvps901Δvps902 cells by electron microscopy. These data strongly suggest that Vps901 and Vps902 are cooperatively involved in the regulation of cellular functions, such as cell morphology, sexual development, response to ion stresses, and vacuole formation, via Rab5 signaling pathways in fission yeast cells. - Highlights: • Roles of Rab5 activator VPS9 proteins in cellular functions. • Cooperation between VPS9 proteins in Rab5 signaling pathway. • Roles of each VPS9 protein in Rab5 signaling pathway are discussed.

  10. Engineering of a mammalian O-glycosylation pathway in the yeast Saccharomyces cerevisiae: production of O-fucosylated epidermal growth factor domains.

    Science.gov (United States)

    Chigira, Yuko; Oka, Takuji; Okajima, Tetsuya; Jigami, Yoshifumi

    2008-04-01

    Development of a heterologous system for the production of homogeneous sugar structures has the potential to elucidate structure-function relationships of glycoproteins. In the current study, we used an artificial O-glycosylation pathway to produce an O-fucosylated epidermal growth factor (EGF) domain in Saccharomyces cerevisiae. The in vivo O-fucosylation system was constructed via expression of genes that encode protein O-fucosyltransferase 1 and the EGF domain, along with genes whose protein products convert cytoplasmic GDP-mannose to GDP-fucose. This system allowed identification of an endogenous ability of S. cerevisiae to transport GDP-fucose. Moreover, expression of EGF domain mutants in this system revealed the different contribution of three disulfide bonds to in vivo O-fucosylation. In addition, lectin blotting revealed differences in the ability of fucose-specific lectin to bind the O-fucosylated structure of EGF domains from human factors VII and IX. Further introduction of the human fringe gene into yeast equipped with the in vivo O-fucosylation system facilitated the addition of N-acetylglucosamine to the EGF domain from factor IX but not from factor VII. The results suggest that engineering of an O-fucosylation system in yeast provides a powerful tool for producing proteins with homogenous carbohydrate chains. Such proteins can be used for the analysis of substrate specificity and the production of antibodies that recognize O-glycosylated EGF domains.

  11. L-arabinose fermenting yeast

    Science.gov (United States)

    Zhang, Min; Singh, Arjun; Suominen, Pirkko; Knoshaug, Eric; Franden, Mary Ann; Jarvis, Eric

    2013-02-12

    An L-arabinose utilizing yeast strain is provided for the production of ethanol by introducing and expressing bacterial araA, araB and araD genes. L-arabinose transporters are also introduced into the yeast to enhance the uptake of arabinose. The yeast carries additional genomic mutations enabling it to consume L-arabinose, even as the only carbon source, and to produce ethanol. A yeast strain engineered to metabolize arabinose through a novel pathway is also disclosed. Methods of producing ethanol include utilizing these modified yeast strains.

  12. A Western blot-based investigation of the yeast secretory pathway designed for an intermediate-level undergraduate cell biology laboratory.

    Science.gov (United States)

    Hood-Degrenier, Jennifer K

    2008-01-01

    The movement of newly synthesized proteins through the endomembrane system of eukaryotic cells, often referred to generally as the secretory pathway, is a topic covered in most intermediate-level undergraduate cell biology courses. An article previously published in this journal described a laboratory exercise in which yeast mutants defective in two distinct steps of protein secretion were differentiated using a genetic reporter designed specifically to identify defects in the first step of the pathway, the insertion of proteins into the endoplasmic reticulum (Vallen, 2002). We have developed two versions of a Western blotting assay that serves as a second way of distinguishing the two secretory mutants, which we pair with the genetic assay in a 3-wk laboratory module. A quiz administered before and after students participated in the lab activities revealed significant postlab gains in their understanding of the secretory pathway and experimental techniques used to study it. A second survey administered at the end of the lab module assessed student perceptions of the efficacy of the lab activities; the results of this survey indicated that the experiments were successful in meeting a set of educational goals defined by the instructor.

  13. MiYA, an efficient machine-learning workflow in conjunction with the YeastFab assembly strategy for combinatorial optimization of heterologous metabolic pathways in Saccharomyces cerevisiae.

    Science.gov (United States)

    Zhou, Yikang; Li, Gang; Dong, Junkai; Xing, Xin-Hui; Dai, Junbiao; Zhang, Chong

    2018-05-01

    Facing boosting ability to construct combinatorial metabolic pathways, how to search the metabolic sweet spot has become the rate-limiting step. We here reported an efficient Machine-learning workflow in conjunction with YeastFab Assembly strategy (MiYA) for combinatorial optimizing the large biosynthetic genotypic space of heterologous metabolic pathways in Saccharomyces cerevisiae. Using β-carotene biosynthetic pathway as example, we first demonstrated that MiYA has the power to search only a small fraction (2-5%) of combinatorial space to precisely tune the expression level of each gene with a machine-learning algorithm of an artificial neural network (ANN) ensemble to avoid over-fitting problem when dealing with a small number of training samples. We then applied MiYA to improve the biosynthesis of violacein. Feed with initial data from a colorimetric plate-based, pre-screened pool of 24 strains producing violacein, MiYA successfully predicted, and verified experimentally, the existence of a strain that showed a 2.42-fold titer improvement in violacein production among 3125 possible designs. Furthermore, MiYA was able to largely avoid the branch pathway of violacein biosynthesis that makes deoxyviolacein, and produces very pure violacein. Together, MiYA combines the advantages of standardized building blocks and machine learning to accelerate the Design-Build-Test-Learn (DBTL) cycle for combinatorial optimization of metabolic pathways, which could significantly accelerate the development of microbial cell factories. Copyright © 2018 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  14. Signaling alkaline pH stress in the yeast Saccharomyces cerevisiae through the Wsc1 cell surface sensor and the Slt2 MAPK pathway.

    Science.gov (United States)

    Serrano, Raquel; Martín, Humberto; Casamayor, Antonio; Ariño, Joaquín

    2006-12-29

    Alkalinization of the external environment represents a stress situation for Saccharomyces cerevisiae. Adaptation to this circumstance involves the activation of diverse response mechanisms, the components of which are still largely unknown. We show here that mutation of members of the cell integrity Pkc1/Slt2 MAPK module, as well as upstream and downstream elements of the system, confers sensitivity to alkali. Alkalinization resulted in fast and transient activation of the Slt2 MAPK, which depended on the integrity of the kinase module and was largely abolished by sorbitol. Lack of Wsc1, removal of specific extracellular and intracellular domains, or substitution of Tyr(303) in this putative membrane stress sensor rendered cells sensitive to alkali and considerably decreased alkali-induced Slt2 activation. In contrast, constitutive activation of Slt2 by the bck1-20 allele increased pH tolerance in the wsc1 mutant. DNA microarray analysis revealed that several genes encoding cell wall proteins, such as GSC2/FKS2, DFG5, SKT5, and CRH1, were induced, at least in part, by high pH in an Slt2-dependent manner. We observed that dfg5, skt5, and particularly dfg5 skt5 cells were alkali-sensitive. Therefore, our results show that an alkaline environment imposes a stress condition on the yeast cell wall. We propose that the Slt2-mediated MAPK pathway plays an important role in the adaptive response to this insult and that Wsc1 participates as an essential cell-surface pH sensor. Moreover, these results provide a new example of the complexity of the response of budding yeast to the alkalinization of the environment.

  15. On the Evolution of Specificity in Members of the Yeast Amino Acid Transporter Family as Parts of Specific Metabolic Pathways

    Directory of Open Access Journals (Sweden)

    Christos Gournas

    2018-05-01

    Full Text Available In the recent years, molecular modeling and substrate docking, coupled with biochemical and genetic analyses have identified the substrate-binding residues of several amino acid transporters of the yeast amino acid transporter (YAT family. These consist of (a residues conserved across YATs that interact with the invariable part of amino acid substrates and (b variable residues that interact with the side chain of the amino acid substrate and thus define specificity. Secondary structure sequence alignments showed that the positions of these residues are conserved across YATs and could thus be used to predict the specificity of YATs. Here, we discuss the potential of combining molecular modeling and structural alignments with intra-species phylogenetic comparisons of transporters, in order to predict the function of uncharacterized members of the family. We additionally define some orphan branches which include transporters with potentially novel, and to be characterized specificities. In addition, we discuss the particular case of the highly specific l-proline transporter, PrnB, of Aspergillus nidulans, whose gene is part of a cluster of genes required for the utilization of proline as a carbon and/or nitrogen source. This clustering correlates with transcriptional regulation of these genes, potentially leading to the efficient coordination of the uptake of externally provided l-Pro via PrnB and its enzymatic degradation in the cell.

  16. Comparison of preribosomal RNA processing pathways in yeast, plant and human cells - focus on coordinated action of endo- and exoribonucleases.

    Science.gov (United States)

    Tomecki, Rafal; Sikorski, Pawel J; Zakrzewska-Placzek, Monika

    2017-07-01

    Proper regulation of ribosome biosynthesis is mandatory for cellular adaptation, growth and proliferation. Ribosome biogenesis is the most energetically demanding cellular process, which requires tight control. Abnormalities in ribosome production have severe consequences, including developmental defects in plants and genetic diseases (ribosomopathies) in humans. One of the processes occurring during eukaryotic ribosome biogenesis is processing of the ribosomal RNA precursor molecule (pre-rRNA), synthesized by RNA polymerase I, into mature rRNAs. It must not only be accurate but must also be precisely coordinated with other phenomena leading to the synthesis of functional ribosomes: RNA modification, RNA folding, assembly with ribosomal proteins and nucleocytoplasmic RNP export. A multitude of ribosome biogenesis factors ensure that these events take place in a correct temporal order. Among them are endo- and exoribonucleases involved in pre-rRNA processing. Here, we thoroughly present a wide spectrum of ribonucleases participating in rRNA maturation, focusing on their biochemical properties, regulatory mechanisms and substrate specificity. We also discuss cooperation between various ribonucleolytic activities in particular stages of pre-rRNA processing, delineating major similarities and differences between three representative groups of eukaryotes: yeast, plants and humans. © 2017 Federation of European Biochemical Societies.

  17. Assessment of FUN-1 vital dye staining: Yeast with a block in the vacuolar sorting pathway have impaired ability to form CIVS when stained with FUN-1 fluorescent dye.

    Science.gov (United States)

    Essary, Brandin D; Marshall, Pamela A

    2009-08-01

    FUN-1 [2-chloro-4-(2,3-dihydro-3-methyl-(benzo-1,3-thiazol-2-yl)-methylidene)-1-phenylquinolinium iodide] is a fluorescent dye used in studies of yeast and other fungi to monitor cell viability in the research lab and to assay for active fungal infection in the clinical setting. When the plasma membrane is intact, fungal cells internalize FUN-1 and the dye is seen as diffuse green cytosolic fluorescence. FUN-1 is then transported to the vacuole in metabolically active wild type cells and subsequently is compacted into fluorescent red cylindrical intravacuolar structures (CIVS) by an unknown transport pathway. This dye is used to determine yeast viability, as only live cells form CIVS. However, in live Saccharomyces cerevisiae with impaired protein sorting to the yeast vacuole, we report decreased to no CIVS formation, depending on the cellular location of the block in the sorting pathway. Cells with a block in vesicle-mediated transport from the Golgi to prevacuolar compartment (PVC) or with a block in recycling from the PVC to the Golgi demonstrate a substantial impairment in CIVS formation. Instead, the FUN-1 dye is seen either in small punctate structures under fluorescence or as diffuse red cytosol under white light. Thus, researchers using FUN-1 should be cognizant of the limitations of this procedure in determining cell viability as there are viable yeast mutants with impaired CIVS formation.

  18. Characterization of new mutants in the early part of the yeast secretory pathway isolated by a [3H]mannose suicide selection

    International Nuclear Information System (INIS)

    Newman, A.P.; Ferro-Novick, S.

    1987-01-01

    We have adapted a [ 3 H]mannose suicide selection to identify mutations in additional genes which function in the early part of the yeast secretory pathway. Thus far this protocol has led to the identification of two new genes which are implicated in this process, as well as additional alleles of previously identified genes. The new mutants, bet1 and bet2, are temperature sensitive for growth and protein transport. Thin section analysis has revealed the accumulation of a network of endoplasmic reticulum (ER) at the restrictive temperature (37 0 C). Precursors of exported proteins that accumulate in the cell at 37 0 C are terminally core glycosylated. These observations suggest that the transport of precursors is blocked subsequent to translocation into the ER but before entry into the Golgi apparatus. The bet1 and bet2 mutants define two new complementation groups which have the same properties as previously identified ER-accumulating mutants. This and previous findings suggest that protein exit from the ER and entry into the Golgi apparatus is a complex process requiring at least 11 genes

  19. Temperature-sensitive defects of the GSP1gene, yeast Ran homologue, activate the Tel1-dependent pathway

    International Nuclear Information System (INIS)

    Hayashi, Naoyuki; Murakami, Seishi; Tsurusaki, Susumu; Nagaura, Zen-ichiro; Oki, Masaya; Nishitani, Hideo; Kobayashi, Masahiko; Shimizu, Hiroko; Yamamoto, Ken-ichi; Nishimoto, Takeharu

    2007-01-01

    RanGTPase is involved in many cellular processes. It functions in nuclear-cytosolic transport and centrosome formation. Ran also localizes to chromatin as RCC1 does, its guanine nucleotide exchange factor, but Ran's function on chromatin is not known. We found that gsp1, a temperature-sensitive mutant of GSP1, a Saccharomyces cerevisiae Ran homologue, suppressed the hydroxyurea (HU) and ultra violet (UV) sensitivities of the mec1 mutant. In UV-irradiated mec1 gsp1 cells, Rad53 was phosphorylated despite the lack of Mec1. This suppression depended on the TEL1 gene, given that the triple mutant, mec1 gsp1 tel1, was unable to grow. The gsp1 mutations also suppressed the HU sensitivity of the rad9 mutant in a Tel1-dependent manner, but not the HU sensitivity of the rad53 mutant. These results indicated that Rad53 was activated by the Tel1 pathway in mec1 gsp1 cells, suggesting that Gsp1 helps regulate the role switching the ATM family kinases Mec1 and Tel1

  20. Interaction of Yna1 and Yna2 Is Required for Nuclear Accumulation and Transcriptional Activation of the Nitrate Assimilation Pathway in the Yeast Hansenula polymorpha.

    Science.gov (United States)

    Silvestrini, Lucia; Rossi, Beatrice; Gallmetzer, Andreas; Mathieu, Martine; Scazzocchio, Claudio; Berardi, Enrico; Strauss, Joseph

    2015-01-01

    A few yeasts, including Hansenula polymorpha are able to assimilate nitrate and use it as nitrogen source. The genes necessary for nitrate assimilation are organised in this organism as a cluster comprising those encoding nitrate reductase (YNR1), nitrite reductase (YNI1), a high affinity transporter (YNT1), as well as the two pathway specific Zn(II)2Cys2 transcriptional activators (YNA1, YNA2). Yna1p and Yna2p mediate induction of the system and here we show that their functions are interdependent. Yna1p activates YNA2 as well as its own (YNA1) transcription thus forming a nitrate-dependent autoactivation loop. Using a split-YFP approach we demonstrate here that Yna1p and Yna2p form a heterodimer independently of the inducer and despite both Yna1p and Yna2p can occupy the target promoter as mono- or homodimer individually, these proteins are transcriptionally incompetent. Subsequently, the transcription factors target genes containing a conserved DNA motif (termed nitrate-UAS) determined in this work by in vitro and in vivo protein-DNA interaction studies. These events lead to a rearrangement of the chromatin landscape on the target promoters and are associated with the onset of transcription of these target genes. In contrast to other fungi and plants, in which nuclear accumulation of the pathway-specific transcription factors only occur in the presence of nitrate, Yna1p and Yna2p are constitutively nuclear in H. polymorpha. Yna2p is needed for this nuclear accumulation and Yna1p is incapable of strictly positioning in the nucleus without Yna2p. In vivo DNA footprinting and ChIP analyses revealed that the permanently nuclear Yna1p/Yna2p heterodimer only binds to the nitrate-UAS when the inducer is present. The nitrate-dependent up-regulation of one partner protein in the heterodimeric complex is functionally similar to the nitrate-dependent activation of nuclear accumulation in other systems.

  1. Genetic and metabolomic dissection of the ergothioneine and selenoneine biosynthetic pathway in the fission yeast, S. pombe, and construction of an overproduction system.

    Directory of Open Access Journals (Sweden)

    Tomáš Pluskal

    Full Text Available Ergothioneine is a small, sulfur-containing metabolite (229 Da synthesized by various species of bacteria and fungi, which can accumulate to millimolar levels in tissues or cells (e.g. erythrocytes of higher eukaryotes. It is commonly marketed as a dietary supplement due to its proposed protective and antioxidative functions. In this study we report the genes forming the two-step ergothioneine biosynthetic pathway in the fission yeast, Schizosaccharomyces pombe. We identified the first gene, egt1+ (SPBC1604.01, by sequence homology to previously published genes from Neurospora crassa and Mycobacterium smegmatis. We showed, using metabolomic analysis, that the Δegt1 deletion mutant completely lacked ergothioneine and its precursors (trimethyl histidine/hercynine and hercynylcysteine sulfoxide. Since the second step of ergothioneine biosynthesis has not been characterized in eukaryotes, we examined four putative homologs (Nfs1/SPBC21D10.11c, SPAC11D3.10, SPCC777.03c, and SPBC660.12c of the corresponding mycobacterial enzyme EgtE. Among deletion mutants of these genes, only one (ΔSPBC660.12c, designated Δegt2 showed a substantial decrease in ergothioneine, accompanied by accumulation of its immediate precursor, hercynylcysteine sulfoxide. Ergothioneine-deficient strains exhibited no phenotypic defects during vegetative growth or quiescence. To effectively study the role of ergothioneine, we constructed an egt1+ overexpression system by replacing its native promoter with the nmt1+ promoter, which is inducible in the absence of thiamine. We employed three versions of the nmt1 promoter with increasing strength of expression and confirmed corresponding accumulations of ergothioneine. We quantified the intracellular concentration of ergothioneine in S. pombe (0.3, 157.4, 41.6, and up to 1606.3 µM in vegetative, nitrogen-starved, glucose-starved, and egt1+-overexpressing cells, respectively and described its gradual accumulation under long

  2. FACT, the Bur kinase pathway, and the histone co-repressor HirC have overlapping nucleosome-related roles in yeast transcription elongation.

    Directory of Open Access Journals (Sweden)

    Jennifer R Stevens

    Full Text Available Gene transcription is constrained by the nucleosomal nature of chromosomal DNA. This nucleosomal barrier is modulated by FACT, a conserved histone-binding heterodimer. FACT mediates transcription-linked nucleosome disassembly and also nucleosome reassembly in the wake of the RNA polymerase II transcription complex, and in this way maintains the repression of 'cryptic' promoters found within some genes. Here we focus on a novel mutant version of the yeast FACT subunit Spt16 that supplies essential Spt16 activities but impairs transcription-linked nucleosome reassembly in dominant fashion. This Spt16 mutant protein also has genetic effects that are recessive, which we used to show that certain Spt16 activities collaborate with histone acetylation and the activities of a Bur-kinase/Spt4-Spt5/Paf1C pathway that facilitate transcription elongation. These collaborating activities were opposed by the actions of Rpd3S, a histone deacetylase that restores a repressive chromatin environment in a transcription-linked manner. Spt16 activity paralleling that of HirC, a co-repressor of histone gene expression, was also found to be opposed by Rpd3S. Our findings suggest that Spt16, the Bur/Spt4-Spt5/Paf1C pathway, and normal histone abundance and/or stoichiometry, in mutually cooperative fashion, facilitate nucleosome disassembly during transcription elongation. The recessive nature of these effects of the mutant Spt16 protein on transcription-linked nucleosome disassembly, contrasted to its dominant negative effect on transcription-linked nucleosome reassembly, indicate that mutant FACT harbouring the mutant Spt16 protein competes poorly with normal FACT at the stage of transcription-linked nucleosome disassembly, but effectively with normal FACT for transcription-linked nucleosome reassembly. This functional difference is consistent with the idea that FACT association with the transcription elongation complex depends on nucleosome disassembly, and that the

  3. The pathway by which the yeast protein kinase Snf1p controls acquisition of sodium tolerance is different from that mediating glucose regulation.

    Science.gov (United States)

    Ye, Tian; Elbing, Karin; Hohmann, Stefan

    2008-09-01

    It recently became apparent that the highly conserved Snf1p protein kinase plays roles in controlling different cellular processes in the yeast Saccharomyces cerevisiae, in addition to its well-known function in glucose repression/derepression. We have previously reported that Snf1p together with Gis4p controls ion homeostasis by regulating expression of ENA1, which encodes the Ena1p Na(+) extrusion system. In this study we found that Snf1p is rapidly phosphorylated when cells are exposed to NaCl and this phosphorylation is required for the role of Snf1p in Na(+) tolerance. In contrast to activation by low glucose levels, the salt-induced phosphorylation of Snf1p promoted neither phosphorylation nor nuclear export of the Mig1p repressor. The mechanism that prevents Mig1p phosphorylation by active Snf1p under salt stress does not involve either hexokinase PII or the Gis4p regulator. Instead, Snf1p may mediate upregulation of ENA1 expression via the repressor Nrg1p. Activation of Snf1p in response to glucose depletion requires any of the three upstream protein kinases Sak1p, Tos3p and Elm1p, with Sak1p playing the most prominent role. The same upstream kinases were required for salt-induced Snf1p phosphorylation, and also under these conditions Sak1p played the most prominent role. Unexpectedly, however, it appears that Elm1p plays a dual role in acquisition of salt tolerance by activating Snf1p and in a presently unknown parallel pathway. Together, these results indicate that under salt stress Snf1p takes part in a different pathway from that during glucose depletion and this role is performed together as well as in parallel with its upstream kinase Elm1p. Snf1p appears to be part of a wider functional network than previously anticipated and the full complexity of this network remains to be elucidated.

  4. Signature gene expressions of cell wall integrity pathway concur with tolerance response of industrial yeast Saccharomyces cerevisiae against biomass pretreatment inhibitors

    Science.gov (United States)

    Traditional industrial ethanologenic yeast Saccharomyces cerevisiae has a robust performance under various environmental conditions and can be served as a candidate for the next-generation biocatalyst development for advanced biofuels production using lignocellulose mateials. Overcoming toxic compou...

  5. Genetically engineered yeast

    DEFF Research Database (Denmark)

    2014-01-01

    A genetically modified Saccharomyces cerevisiae comprising an active fermentation pathway producing 3-HP expresses an exogenous gene expressing the aminotransferase YhxA from Bacillus cereus AH1272 catalysing a transamination reaction between beta-alanine and pyruvate to produce malonate semialde......A genetically modified Saccharomyces cerevisiae comprising an active fermentation pathway producing 3-HP expresses an exogenous gene expressing the aminotransferase YhxA from Bacillus cereus AH1272 catalysing a transamination reaction between beta-alanine and pyruvate to produce malonate...... semialdehyde. The yeast may also express a 3-hydroxyisobutyrate dehydrogenase (HIBADH) and a 3-hydroxypropanoate dehydrogenase (3-HPDH) and aspartate 1-decarboxylase. Additionally the yeast may express pyruvate carboxylase and aspartate aminotransferase....

  6. The freeze-thaw stress response of the yeast Saccharomyces cerevisiae is growth phase specific and is controlled by nutritional state via the RAS-cyclic AMP signal transduction pathway.

    Science.gov (United States)

    Park, J I; Grant, C M; Attfield, P V; Dawes, I W

    1997-10-01

    The ability of cells to survive freezing and thawing is expected to depend on the physiological conditions experienced prior to freezing. We examined factors affecting yeast cell survival during freeze-thaw stress, including those associated with growth phase, requirement for mitochondrial functions, and prior stress treatment(s), and the role played by relevant signal transduction pathways. The yeast Saccharomyces cerevisiae was frozen at -20 degrees C for 2 h (cooling rate, less than 4 degrees C min-1) and thawed on ice for 40 min. Supercooling occurred without reducing cell survival and was followed by freezing. Loss of viability was proportional to the freezing duration, indicating that freezing is the main determinant of freeze-thaw damage. Regardless of the carbon source used, the wild-type strain and an isogenic petite mutant ([rho 0]) showed the same pattern of freeze-thaw tolerance throughout growth, i.e., high resistance during lag phase and low resistance during log phase, indicating that the response to freeze-thaw stress is growth phase specific and not controlled by glucose repression. In addition, respiratory ability and functional mitochondria are necessary to confer full resistance to freeze-thaw stress. Both nitrogen and carbon source starvation led to freeze-thaw tolerance. The use of strains affected in the RAS-cyclic AMP (RAS-cAMP) pathway or supplementation of an rca1 mutant (defective in the cAMP phosphodiesterase gene) with cAMP showed that the freeze-thaw response of yeast is under the control of the RAS-cAMP pathway. Yeast did not adapt to freeze-thaw stress following repeated freeze-thaw treatment with or without a recovery period between freeze-thaw cycles, nor could it adapt following pretreatment by cold shock. However, freeze-thaw tolerance of yeast cells was induced during fermentative and respiratory growth by pretreatment with H2O2, cycloheximide, mild heat shock, or NaCl, indicating that cross protection between freeze-thaw stress

  7. Multiple Transceptors for Macro- and Micro-Nutrients Control Diverse Cellular Properties Through the PKA Pathway in Yeast: A Paradigm for the Rapidly Expanding World of Eukaryotic Nutrient Transceptors Up to Those in Human Cells.

    Science.gov (United States)

    Steyfkens, Fenella; Zhang, Zhiqiang; Van Zeebroeck, Griet; Thevelein, Johan M

    2018-01-01

    The nutrient composition of the medium has dramatic effects on many cellular properties in the yeast Saccharomyces cerevisiae . In addition to the well-known specific responses to starvation for an essential nutrient, like nitrogen or phosphate, the presence of fermentable sugar or a respirative carbon source leads to predominance of fermentation or respiration, respectively. Fermenting and respiring cells also show strong differences in other properties, like storage carbohydrate levels, general stress tolerance and cellular growth rate. However, the main glucose repression pathway, which controls the switch between respiration and fermentation, is not involved in control of these properties. They are controlled by the protein kinase A (PKA) pathway. Addition of glucose to respiring yeast cells triggers cAMP synthesis, activation of PKA and rapid modification of its targets, like storage carbohydrate levels, general stress tolerance and growth rate. However, starvation of fermenting cells in a glucose medium for any essential macro- or micro-nutrient counteracts this effect, leading to downregulation of PKA and its targets concomitant with growth arrest and entrance into G0. Re-addition of the lacking nutrient triggers rapid activation of the PKA pathway, without involvement of cAMP as second messenger. Investigation of the sensing mechanism has revealed that the specific high-affinity nutrient transporter(s) induced during starvation function as transporter-receptors or transceptors for rapid activation of PKA upon re-addition of the missing substrate. In this way, transceptors have been identified for amino acids, ammonium, phosphate, sulfate, iron, and zinc. We propose a hypothesis for regulation of PKA activity by nutrient transceptors to serve as a conceptual framework for future experimentation. Many properties of transceptors appear to be similar to those of classical receptors and nutrient transceptors may constitute intermediate forms in the development

  8. Multiple Transceptors for Macro- and Micro-Nutrients Control Diverse Cellular Properties Through the PKA Pathway in Yeast: A Paradigm for the Rapidly Expanding World of Eukaryotic Nutrient Transceptors Up to Those in Human Cells

    Directory of Open Access Journals (Sweden)

    Fenella Steyfkens

    2018-03-01

    Full Text Available The nutrient composition of the medium has dramatic effects on many cellular properties in the yeast Saccharomyces cerevisiae. In addition to the well-known specific responses to starvation for an essential nutrient, like nitrogen or phosphate, the presence of fermentable sugar or a respirative carbon source leads to predominance of fermentation or respiration, respectively. Fermenting and respiring cells also show strong differences in other properties, like storage carbohydrate levels, general stress tolerance and cellular growth rate. However, the main glucose repression pathway, which controls the switch between respiration and fermentation, is not involved in control of these properties. They are controlled by the protein kinase A (PKA pathway. Addition of glucose to respiring yeast cells triggers cAMP synthesis, activation of PKA and rapid modification of its targets, like storage carbohydrate levels, general stress tolerance and growth rate. However, starvation of fermenting cells in a glucose medium for any essential macro- or micro-nutrient counteracts this effect, leading to downregulation of PKA and its targets concomitant with growth arrest and entrance into G0. Re-addition of the lacking nutrient triggers rapid activation of the PKA pathway, without involvement of cAMP as second messenger. Investigation of the sensing mechanism has revealed that the specific high-affinity nutrient transporter(s induced during starvation function as transporter-receptors or transceptors for rapid activation of PKA upon re-addition of the missing substrate. In this way, transceptors have been identified for amino acids, ammonium, phosphate, sulfate, iron, and zinc. We propose a hypothesis for regulation of PKA activity by nutrient transceptors to serve as a conceptual framework for future experimentation. Many properties of transceptors appear to be similar to those of classical receptors and nutrient transceptors may constitute intermediate forms in

  9. The methylotrophic yeast Hansenula polymorpha contains an inducible import pathway for peroxisomal matrix proteins with an N-terminal targeting signal (PTS2 proteins)

    NARCIS (Netherlands)

    Faber, Klaas Nico; Haima, Pieter; Gietl, Christine; Harder, Willem; Ab, Geert; Veenhuis, Marten

    1994-01-01

    Two main types of peroxisomal targeting signals have been identified that reside either at the extreme C terminus (PTS1) or the N terminus (PTS2) of the protein. In the methylotrophic yeast Hansenula polymorpha the majority of peroxisomal matrix proteins are of the PTS1 type. Thus far, for H.

  10. Yeast glycolipid biosurfactants.

    Science.gov (United States)

    Jezierska, Sylwia; Claus, Silke; Van Bogaert, Inge

    2017-10-25

    Various yeasts, both conventional and exotic ones, are known to produce compounds useful to mankind. Ethanol is the most known of these compounds, but more complex molecules such as amphiphilic biosurfactants can also be derived from eukaryotic microorganisms at an industrially and commercially relevant scale. Among them, glycolipids are the most promising, due to their attractive properties and high product titers. Many of these compounds can be considered as secondary metabolites with a specific function for the host. Hence, a dedicated biosynthetic process enables regulation and combines pathways delivering the lipidic moiety and the hydrophilic carbohydrate part of the glycolipid. In this Review, we will discuss the biosynthetic and regulatory aspects of the yeast-derived sophorolipids, mannosylerythritol lipids, and cellobiose lipids, with special emphasis on the relation between glycolipid synthesis and the general lipid metabolism. © 2017 Federation of European Biochemical Societies.

  11. Hyperpolarized [U-(2) H, U-(13) C]Glucose reports on glycolytic and pentose phosphate pathway activity in EL4 tumors and glycolytic activity in yeast cells.

    Science.gov (United States)

    Timm, Kerstin N; Hartl, Johannes; Keller, Markus A; Hu, De-En; Kettunen, Mikko I; Rodrigues, Tiago B; Ralser, Markus; Brindle, Kevin M

    2015-12-01

    A resonance at ∼181 ppm in the (13) C spectra of tumors injected with hyperpolarized [U-(2) H, U-(13) C]glucose was assigned to 6-phosphogluconate (6PG), as in previous studies in yeast, whereas in breast cancer cells in vitro this resonance was assigned to 3-phosphoglycerate (3PG). These peak assignments were investigated here using measurements of 6PG and 3PG (13) C-labeling using liquid chromatography tandem mass spectrometry (LC-MS/MS) METHODS: Tumor-bearing mice were injected with (13) C6 glucose and the (13) C-labeled and total 6PG and 3PG concentrations measured. (13) C MR spectra of glucose-6-phosphate dehydrogenase deficient (zwf1Δ) and wild-type yeast were acquired following addition of hyperpolarized [U-(2) H, U-(13) C]glucose and again (13) C-labeled and total 6PG and 3PG were measured by LC-MS/MS RESULTS: Tumor (13) C-6PG was more abundant than (13) C-2PG/3PG and the resonance at ∼181 ppm matched more closely that of 6PG. (13) C MR spectra of wild-type and zwf1Δ yeast cells showed a resonance at ∼181 ppm after labeling with hyperpolarized [U-(2) H, U-(13) C]glucose, however, there was no 6PG in zwf1Δ cells. In the wild-type cells 3PG was approximately four-fold more abundant than 6PG CONCLUSION: The resonance at ∼181 ppm in (13) C MR spectra following injection of hyperpolarized [U-(2) H, U-(13) C]glucose originates predominantly from 6PG in EL4 tumors and 3PG in yeast cells. © 2014 Wiley Periodicals, Inc.

  12. Deletion of the Ustilago maydis ortholog of the Aspergillus sporulation regulator medA affects mating and virulence through pheromone response

    Science.gov (United States)

    Mating of compatible haploid cells of Ustilago maydis is essential for infection and disease development in the host. For mating and subsequent filamentous growth and pathogenicity, the transcription factor, prf1 is necessary. Prf1 is in turn regulated by the cAMP and MAPK pathways and other regul...

  13. Nucleotide excision repair in yeast

    NARCIS (Netherlands)

    Eijk, Patrick van

    2012-01-01

    Nucleotide Excision Repair (NER) is a conserved DNA repair pathway capable of removing a broad spectrum of DNA damage. In human cells a defect in NER leads to the disorder Xeroderma pigmentosum (XP). The yeast Saccharomyces cerevisiae is an excellent model organism to study the mechanism of NER. The

  14. Expression of a Human Cytochrome P450 in Yeast Permits Analysis of Pathways for Response to and Repair of Aflatoxin-Induced DNA Damage†

    OpenAIRE

    Guo, Yingying; Breeden, Linda L.; Zarbl, Helmut; Preston, Bradley D.; Eaton, David L.

    2005-01-01

    Aflatoxin B1 (AFB1) is a human hepatotoxin and hepatocarcinogen produced by the mold Aspergillus flavus. In humans, AFB1 is primarily bioactivated by cytochrome P450 1A2 (CYP1A2) and 3A4 to a genotoxic epoxide that forms N7-guanine DNA adducts. A series of yeast haploid mutants defective in DNA repair and cell cycle checkpoints were transformed with human CYP1A2 to investigate how these DNA adducts are repaired. Cell survival and mutagenesis following aflatoxin B1 treatment was assayed in str...

  15. The yeast replicative aging model.

    Science.gov (United States)

    He, Chong; Zhou, Chuankai; Kennedy, Brian K

    2018-03-08

    It has been nearly three decades since the budding yeast Saccharomyces cerevisiae became a significant model organism for aging research and it has emerged as both simple and powerful. The replicative aging assay, which interrogates the number of times a "mother" cell can divide and produce "daughters", has been a stalwart in these studies, and genetic approaches have led to the identification of hundreds of genes impacting lifespan. More recently, cell biological and biochemical approaches have been developed to determine how cellular processes become altered with age. Together, the tools are in place to develop a holistic view of aging in this single-celled organism. Here, we summarize the current state of understanding of yeast replicative aging with a focus on the recent studies that shed new light on how aging pathways interact to modulate lifespan in yeast. Copyright © 2018. Published by Elsevier B.V.

  16. Gβ promotes pheromone receptor polarization and yeast chemotropism by inhibiting receptor phosphorylation.

    Science.gov (United States)

    Ismael, Amber; Tian, Wei; Waszczak, Nicholas; Wang, Xin; Cao, Youfang; Suchkov, Dmitry; Bar, Eli; Metodiev, Metodi V; Liang, Jie; Arkowitz, Robert A; Stone, David E

    2016-04-12

    Gradient-directed cell migration (chemotaxis) and growth (chemotropism) are processes that are essential to the development and life cycles of all species. Cells use surface receptors to sense the shallow chemical gradients that elicit chemotaxis and chemotropism. Slight asymmetries in receptor activation are amplified by downstream signaling systems, which ultimately induce dynamic reorganization of the cytoskeleton. During the mating response of budding yeast, a model chemotropic system, the pheromone receptors on the plasma membrane polarize to the side of the cell closest to the stimulus. Although receptor polarization occurs before and independently of actin cable-dependent delivery of vesicles to the plasma membrane (directed secretion), it requires receptor internalization. Phosphorylation of pheromone receptors by yeast casein kinase 1 or 2 (Yck1/2) stimulates their internalization. We showed that the pheromone-responsive Gβγ dimer promotes the polarization of the pheromone receptor by interacting with Yck1/2 and locally inhibiting receptor phosphorylation. We also found that receptor phosphorylation is essential for chemotropism, independently of its role in inducing receptor internalization. A mathematical model supports the idea that the interaction between Gβγ and Yck1/2 results in differential phosphorylation and internalization of the pheromone receptor and accounts for its polarization before the initiation of directed secretion. Copyright © 2016, American Association for the Advancement of Science.

  17. The yeast rapid tRNA decay pathway competes with elongation factor 1A for substrate tRNAs and acts on tRNAs lacking one or more of several modifications.

    Science.gov (United States)

    Dewe, Joshua M; Whipple, Joseph M; Chernyakov, Irina; Jaramillo, Laura N; Phizicky, Eric M

    2012-10-01

    The structural and functional integrity of tRNA is crucial for translation. In the yeast Saccharomyces cerevisiae, certain aberrant pre-tRNA species are subject to nuclear surveillance, leading to 3' exonucleolytic degradation, and certain mature tRNA species are subject to rapid tRNA decay (RTD) if they are appropriately hypomodified or bear specific destabilizing mutations, leading to 5'-3' exonucleolytic degradation by Rat1 and Xrn1. Thus, trm8-Δ trm4-Δ strains are temperature sensitive due to lack of m(7)G(46) and m(5)C and the consequent RTD of tRNA(Val(AAC)), and tan1-Δ trm44-Δ strains are temperature sensitive due to lack of ac(4)C(12) and Um(44) and the consequent RTD of tRNA(Ser(CGA)) and tRNA(Ser(UGA)). It is unknown how the RTD pathway interacts with translation and other cellular processes, and how generally this pathway acts on hypomodified tRNAs. We provide evidence here that elongation factor 1A (EF-1A) competes with the RTD pathway for substrate tRNAs, since its overexpression suppresses the tRNA degradation and the growth defect of strains subject to RTD, whereas reduced levels of EF-1A have the opposite effect. We also provide evidence that RTD acts on a variety of tRNAs lacking one or more different modifications, since trm1-Δ trm4-Δ mutants are subject to RTD of tRNA(Ser(CGA)) and tRNA(Ser(UGA)) due to lack of m(2,2)G(26) and m(5)C, and since trm8-Δ, tan1-Δ, and trm1-Δ single mutants are each subject to RTD. These results demonstrate that RTD interacts with the translation machinery and acts widely on hypomodified tRNAs.

  18. Evidence of a New Role for the High-Osmolarity Glycerol Mitogen-Activated Protein Kinase Pathway in Yeast: Regulating Adaptation to Citric Acid Stress†

    OpenAIRE

    Lawrence, Clare L.; Botting, Catherine H.; Antrobus, Robin; Coote, Peter J.

    2004-01-01

    Screening the Saccharomyces cerevisiae disruptome, profiling transcripts, and determining changes in protein expression have identified an important new role for the high-osmolarity glycerol (HOG) mitogen-activated protein kinase (MAPK) pathway in the regulation of adaptation to citric acid stress. Deletion of HOG1, SSK1, PBS2, PTC2, PTP2, and PTP3 resulted in sensitivity to citric acid. Furthermore, citric acid resulted in the dual phosphorylation, and thus activation, of Hog1p. Despite mino...

  19. Prions in yeast

    OpenAIRE

    Bezdíčka, Martin

    2013-01-01

    The thesis describes yeast prions and their biological effects on yeast in general. It defines the basic characteristics of yeast prions, that distinguish prions from other proteins. The thesis introduces various possibilities of prion formation, and propagation as well as specific types of yeast prions, including various functions of most studied types of prions. The thesis also focuses on chaperones that affect the state of yeast prions in cells. Lastly, the thesis indicates similarities be...

  20. Vaginal yeast infection

    Science.gov (United States)

    Yeast infection - vagina; Vaginal candidiasis; Monilial vaginitis ... Most women have a vaginal yeast infection at some time. Candida albicans is a common type of fungus. It is often found in small amounts ...

  1. The essence of yeast quiescence.

    Science.gov (United States)

    De Virgilio, Claudio

    2012-03-01

    Like all microorganisms, yeast cells spend most of their natural lifetime in a reversible, quiescent state that is primarily induced by limitation for essential nutrients. Substantial progress has been made in defining the features of quiescent cells and the nutrient-signaling pathways that shape these features. A view that emerges from the wealth of new data is that yeast cells dynamically configure the quiescent state in response to nutritional challenges by using a set of key nutrient-signaling pathways, which (1) regulate pathway-specific effectors, (2) converge on a few regulatory nodes that bundle multiple inputs to communicate unified, graded responses, and (3) mutually modulate their competences to transmit signals. Here, I present an overview of our current understanding of the architecture of these pathways, focusing on how the corresponding core signaling protein kinases (i.e. PKA, TORC1, Snf1, and Pho85) are wired to ensure an adequate response to nutrient starvation, which enables cells to tide over decades, if not centuries, of famine. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  2. Genome-Wide Analysis of Heteroduplex DNA in Mismatch Repair–Deficient Yeast Cells Reveals Novel Properties of Meiotic Recombination Pathways

    Science.gov (United States)

    Martini, Emmanuelle; Borde, Valérie; Legendre, Matthieu; Audic, Stéphane; Regnault, Béatrice; Soubigou, Guillaume; Dujon, Bernard; Llorente, Bertrand

    2011-01-01

    Meiotic DNA double-strand breaks (DSBs) initiate crossover (CO) recombination, which is necessary for accurate chromosome segregation, but DSBs may also repair as non-crossovers (NCOs). Multiple recombination pathways with specific intermediates are expected to lead to COs and NCOs. We revisited the mechanisms of meiotic DSB repair and the regulation of CO formation, by conducting a genome-wide analysis of strand-transfer intermediates associated with recombination events. We performed this analysis in a SK1 × S288C Saccharomyces cerevisiae hybrid lacking the mismatch repair (MMR) protein Msh2, to allow efficient detection of heteroduplex DNAs (hDNAs). First, we observed that the anti-recombinogenic activity of MMR is responsible for a 20% drop in CO number, suggesting that in MMR–proficient cells some DSBs are repaired using the sister chromatid as a template when polymorphisms are present. Second, we observed that a large fraction of NCOs were associated with trans–hDNA tracts constrained to a single chromatid. This unexpected finding is compatible with dissolution of double Holliday junctions (dHJs) during repair, and it suggests the existence of a novel control point for CO formation at the level of the dHJ intermediate, in addition to the previously described control point before the dHJ formation step. Finally, we observed that COs are associated with complex hDNA patterns, confirming that the canonical double-strand break repair model is not sufficient to explain the formation of most COs. We propose that multiple factors contribute to the complexity of recombination intermediates. These factors include repair of nicks and double-stranded gaps, template switches between non-sister and sister chromatids, and HJ branch migration. Finally, the good correlation between the strand transfer properties observed in the absence of and in the presence of Msh2 suggests that the intermediates detected in the absence of Msh2 reflect normal intermediates. PMID

  3. Genome-wide analysis of heteroduplex DNA in mismatch repair-deficient yeast cells reveals novel properties of meiotic recombination pathways.

    Directory of Open Access Journals (Sweden)

    Emmanuelle Martini

    2011-09-01

    Full Text Available Meiotic DNA double-strand breaks (DSBs initiate crossover (CO recombination, which is necessary for accurate chromosome segregation, but DSBs may also repair as non-crossovers (NCOs. Multiple recombination pathways with specific intermediates are expected to lead to COs and NCOs. We revisited the mechanisms of meiotic DSB repair and the regulation of CO formation, by conducting a genome-wide analysis of strand-transfer intermediates associated with recombination events. We performed this analysis in a SK1 × S288C Saccharomyces cerevisiae hybrid lacking the mismatch repair (MMR protein Msh2, to allow efficient detection of heteroduplex DNAs (hDNAs. First, we observed that the anti-recombinogenic activity of MMR is responsible for a 20% drop in CO number, suggesting that in MMR-proficient cells some DSBs are repaired using the sister chromatid as a template when polymorphisms are present. Second, we observed that a large fraction of NCOs were associated with trans-hDNA tracts constrained to a single chromatid. This unexpected finding is compatible with dissolution of double Holliday junctions (dHJs during repair, and it suggests the existence of a novel control point for CO formation at the level of the dHJ intermediate, in addition to the previously described control point before the dHJ formation step. Finally, we observed that COs are associated with complex hDNA patterns, confirming that the canonical double-strand break repair model is not sufficient to explain the formation of most COs. We propose that multiple factors contribute to the complexity of recombination intermediates. These factors include repair of nicks and double-stranded gaps, template switches between non-sister and sister chromatids, and HJ branch migration. Finally, the good correlation between the strand transfer properties observed in the absence of and in the presence of Msh2 suggests that the intermediates detected in the absence of Msh2 reflect normal intermediates.

  4. Regulatory aspects of methanol metabolism in yeasts

    International Nuclear Information System (INIS)

    Trotsenko, Y.A.; Bystrykh, L.V.; Ubiyvovk, V.M.

    1984-01-01

    Formaldehyde is the first and key intermediate in the metabolism of methylotrophic yeasts since it stands at a branch point of pathways for methanol oxidation and assimilation. Methanol and, formaldehyde are toxic compounds which severely affect the growth rate, yield coefficient, etc., of yeasts. Two questions arise when considering regulation of methanol metabolism in yeasts how a nontoxic level of formaldehyde is maintained in the cell and how the formaldehyde flow is distributed into oxidation and assimilation. To answer these questions we studied the role of GSH, which spontaneously binds formaldehyde, yielding S-hydroxymethylglutathione; in vivo rates of formaldehyde dissimilation and assimilation by using [ 14 C]methanol; profiles of enzymes responsible for production and utilization of formaldehyde; and levels of metabolites affecting dissimilation and assimilation of formaldehyde. All of the experiments were carried out with the methylotrophic yeast Candida boidinii KD1. 19 refs., 4 figs., 1 tab

  5. Yeast for virus research

    Science.gov (United States)

    Zhao, Richard Yuqi

    2017-01-01

    Budding yeast (Saccharomyces cerevisiae) and fission yeast (Schizosaccharomyces pombe) are two popular model organisms for virus research. They are natural hosts for viruses as they carry their own indigenous viruses. Both yeasts have been used for studies of plant, animal and human viruses. Many positive sense (+) RNA viruses and some DNA viruses replicate with various levels in yeasts, thus allowing study of those viral activities during viral life cycle. Yeasts are single cell eukaryotic organisms. Hence, many of the fundamental cellular functions such as cell cycle regulation or programed cell death are highly conserved from yeasts to higher eukaryotes. Therefore, they are particularly suited to study the impact of those viral activities on related cellular activities during virus-host interactions. Yeasts present many unique advantages in virus research over high eukaryotes. Yeast cells are easy to maintain in the laboratory with relative short doubling time. They are non-biohazardous, genetically amendable with small genomes that permit genome-wide analysis of virologic and cellular functions. In this review, similarities and differences of these two yeasts are described. Studies of virologic activities such as viral translation, viral replication and genome-wide study of virus-cell interactions in yeasts are highlighted. Impacts of viral proteins on basic cellular functions such as cell cycle regulation and programed cell death are discussed. Potential applications of using yeasts as hosts to carry out functional analysis of small viral genome and to develop high throughput drug screening platform for the discovery of antiviral drugs are presented. PMID:29082230

  6. Cell biology of homologous recombination in yeast

    DEFF Research Database (Denmark)

    Eckert-Boulet, Nadine Valerie; Rothstein, Rodney; Lisby, Michael

    2011-01-01

    Homologous recombination is an important pathway for error-free repair of DNA lesions, such as single- and double-strand breaks, and for rescue of collapsed replication forks. Here, we describe protocols for live cell imaging of single-lesion recombination events in the yeast Saccharomyces...

  7. Molecular Pathways

    Science.gov (United States)

    Lok, Benjamin H.; Powell, Simon N.

    2012-01-01

    The Rad52 protein was largely ignored in humans and other mammals when the mouse knockout revealed a largely “no-effect” phenotype. However, using synthetic lethal approaches to investigate context dependent function, new studies have shown that Rad52 plays a key survival role in cells lacking the function of the BRCA1-BRCA2 pathway of homologous recombination. Biochemical studies also showed significant differences between yeast and human Rad52, in which yeast Rad52 can promote strand invasion of RPA-coated single-stranded DNA in the presence of Rad51, but human Rad52 cannot. This results in the paradox of how is human Rad52 providing Rad51 function: presumably there is something missing in the biochemical assays that exists in-vivo, but the nature of this missing factor is currently unknown. Recent studies have suggested that Rad52 provides back-up Rad51 function for all members of the BRCA1-BRCA2 pathway, suggesting that Rad52 may be a target for therapy in BRCA pathway deficient cancers. Screening for ways to inhibit Rad52 would potentially provide a complementary strategy for targeting BRCA-deficient cancers in addition to PARP inhibitors. PMID:23071261

  8. Yeast: A new oil producer?

    Directory of Open Access Journals (Sweden)

    Beopoulos Athanasios

    2012-01-01

    Full Text Available The increasing demand of plant oils or animal fat for biodiesel and specific lipid derivatives for the oleochemical field (such as lubricants, adhesives or plastics have created price imbalance in both the alimentary and energy field. Moreover, the lack of non-edible oil feedstock has given rise to concerns on land-use practices and on oil production strategies. Recently, much attention has been paid to the exploitation of microbial oils. Most of them present lipid profiles similar in type and composition to plants and could therefore have many advantages as are no competitive with food, have short process cycles and their cultivation is independent of climate factors. Among microorganisms, yeasts seem to be very promising as they can be easily genetically enhanced, are suitable for large-scale fermentation and are devoid of endotoxins. This review will focus on the recent understanding of yeasts lipid metabolism, the succeeding genetic engineering of the lipid pathways and the recent developments on fermentation techniques that pointed out yeasts as promising alternative producers for oil or plastic.

  9. De novo biosynthesis of vanillin in fission yeast (Schizosaccharomyces pombe) and baker's yeast (Saccharomyces cerevisiae).

    Science.gov (United States)

    Hansen, Esben H; Møller, Birger Lindberg; Kock, Gertrud R; Bünner, Camilla M; Kristensen, Charlotte; Jensen, Ole R; Okkels, Finn T; Olsen, Carl E; Motawia, Mohammed S; Hansen, Jørgen

    2009-05-01

    Vanillin is one of the world's most important flavor compounds, with a global market of 180 million dollars. Natural vanillin is derived from the cured seed pods of the vanilla orchid (Vanilla planifolia), but most of the world's vanillin is synthesized from petrochemicals or wood pulp lignins. We have established a true de novo biosynthetic pathway for vanillin production from glucose in Schizosaccharomyces pombe, also known as fission yeast or African beer yeast, as well as in baker's yeast, Saccharomyces cerevisiae. Productivities were 65 and 45 mg/liter, after introduction of three and four heterologous genes, respectively. The engineered pathways involve incorporation of 3-dehydroshikimate dehydratase from the dung mold Podospora pauciseta, an aromatic carboxylic acid reductase (ACAR) from a bacterium of the Nocardia genus, and an O-methyltransferase from Homo sapiens. In S. cerevisiae, the ACAR enzyme required activation by phosphopantetheinylation, and this was achieved by coexpression of a Corynebacterium glutamicum phosphopantetheinyl transferase. Prevention of reduction of vanillin to vanillyl alcohol was achieved by knockout of the host alcohol dehydrogenase ADH6. In S. pombe, the biosynthesis was further improved by introduction of an Arabidopsis thaliana family 1 UDP-glycosyltransferase, converting vanillin into vanillin beta-D-glucoside, which is not toxic to the yeast cells and thus may be accumulated in larger amounts. These de novo pathways represent the first examples of one-cell microbial generation of these valuable compounds from glucose. S. pombe yeast has not previously been metabolically engineered to produce any valuable, industrially scalable, white biotech commodity.

  10. Oxidative Stress and Programmed Cell Death in Yeast

    International Nuclear Information System (INIS)

    Farrugia, Gianluca; Balzan, Rena

    2012-01-01

    Yeasts, such as Saccharomyces cerevisiae, have long served as useful models for the study of oxidative stress, an event associated with cell death and severe human pathologies. This review will discuss oxidative stress in yeast, in terms of sources of reactive oxygen species (ROS), their molecular targets, and the metabolic responses elicited by cellular ROS accumulation. Responses of yeast to accumulated ROS include upregulation of antioxidants mediated by complex transcriptional changes, activation of pro-survival pathways such as mitophagy, and programmed cell death (PCD) which, apart from apoptosis, includes pathways such as autophagy and necrosis, a form of cell death long considered accidental and uncoordinated. The role of ROS in yeast aging will also be discussed.

  11. YMDB: the Yeast Metabolome Database

    Science.gov (United States)

    Jewison, Timothy; Knox, Craig; Neveu, Vanessa; Djoumbou, Yannick; Guo, An Chi; Lee, Jacqueline; Liu, Philip; Mandal, Rupasri; Krishnamurthy, Ram; Sinelnikov, Igor; Wilson, Michael; Wishart, David S.

    2012-01-01

    The Yeast Metabolome Database (YMDB, http://www.ymdb.ca) is a richly annotated ‘metabolomic’ database containing detailed information about the metabolome of Saccharomyces cerevisiae. Modeled closely after the Human Metabolome Database, the YMDB contains >2000 metabolites with links to 995 different genes/proteins, including enzymes and transporters. The information in YMDB has been gathered from hundreds of books, journal articles and electronic databases. In addition to its comprehensive literature-derived data, the YMDB also contains an extensive collection of experimental intracellular and extracellular metabolite concentration data compiled from detailed Mass Spectrometry (MS) and Nuclear Magnetic Resonance (NMR) metabolomic analyses performed in our lab. This is further supplemented with thousands of NMR and MS spectra collected on pure, reference yeast metabolites. Each metabolite entry in the YMDB contains an average of 80 separate data fields including comprehensive compound description, names and synonyms, structural information, physico-chemical data, reference NMR and MS spectra, intracellular/extracellular concentrations, growth conditions and substrates, pathway information, enzyme data, gene/protein sequence data, as well as numerous hyperlinks to images, references and other public databases. Extensive searching, relational querying and data browsing tools are also provided that support text, chemical structure, spectral, molecular weight and gene/protein sequence queries. Because of S. cervesiae's importance as a model organism for biologists and as a biofactory for industry, we believe this kind of database could have considerable appeal not only to metabolomics researchers, but also to yeast biologists, systems biologists, the industrial fermentation industry, as well as the beer, wine and spirit industry. PMID:22064855

  12. Chronological aging-induced apoptosis in yeast

    OpenAIRE

    Fabrizio, Paola; Longo, Valter D.

    2008-01-01

    Saccharomyces cerevisiae is the simplest among the major eukaryotic model organisms for aging and diseases. Longevity in the chronological life span paradigm is measured as the mean and maximum survival period of populations of non-dividing yeast. This paradigm has been used successfully to identify several life-regulatory genes and three evolutionary conserved pro-aging pathways. More recently, Schizosaccharomyces pombe has been shown to age chronologically in a manner that resembles that of...

  13. Yeast genome sequencing:

    DEFF Research Database (Denmark)

    Piskur, Jure; Langkjær, Rikke Breinhold

    2004-01-01

    For decades, unicellular yeasts have been general models to help understand the eukaryotic cell and also our own biology. Recently, over a dozen yeast genomes have been sequenced, providing the basis to resolve several complex biological questions. Analysis of the novel sequence data has shown...... of closely related species helps in gene annotation and to answer how many genes there really are within the genomes. Analysis of non-coding regions among closely related species has provided an example of how to determine novel gene regulatory sequences, which were previously difficult to analyse because...... they are short and degenerate and occupy different positions. Comparative genomics helps to understand the origin of yeasts and points out crucial molecular events in yeast evolutionary history, such as whole-genome duplication and horizontal gene transfer(s). In addition, the accumulating sequence data provide...

  14. Biotechnology of non-Saccharomyces yeasts--the ascomycetes.

    Science.gov (United States)

    Johnson, Eric A

    2013-01-01

    Saccharomyces cerevisiae and several other yeast species are among the most important groups of biotechnological organisms. S. cerevisiae and closely related ascomycetous yeasts are the major producer of biotechnology products worldwide, exceeding other groups of industrial microorganisms in productivity and economic revenues. Traditional industrial attributes of the S. cerevisiae group include their primary roles in food fermentations such as beers, cider, wines, sake, distilled spirits, bakery products, cheese, sausages, and other fermented foods. Other long-standing industrial processes involving S. cerevisae yeasts are production of fuel ethanol, single-cell protein (SCP), feeds and fodder, industrial enzymes, and small molecular weight metabolites. More recently, non-Saccharomyces yeasts (non-conventional yeasts) have been utilized as industrial organisms for a variety of biotechnological roles. Non-Saccharomyces yeasts are increasingly being used as hosts for expression of proteins, biocatalysts and multi-enzyme pathways for the synthesis of fine chemicals and small molecular weight compounds of medicinal and nutritional importance. Non-Saccharomyces yeasts also have important roles in agriculture as agents of biocontrol, bioremediation, and as indicators of environmental quality. Several of these products and processes have reached commercial utility, while others are in advanced development. The objective of this mini-review is to describe processes currently used by industry and those in developmental stages and close to commercialization primarily from non-Saccharomyces yeasts with an emphasis on new opportunities. The utility of S. cerevisiae in heterologous production of selected products is also described.

  15. Nitrile Metabolizing Yeasts

    Science.gov (United States)

    Bhalla, Tek Chand; Sharma, Monica; Sharma, Nitya Nand

    Nitriles and amides are widely distributed in the biotic and abiotic components of our ecosystem. Nitrile form an important group of organic compounds which find their applications in the synthesis of a large number of compounds used as/in pharmaceutical, cosmetics, plastics, dyes, etc>. Nitriles are mainly hydro-lyzed to corresponding amide/acid in organic chemistry. Industrial and agricultural activities have also lead to release of nitriles and amides into the environment and some of them pose threat to human health. Biocatalysis and biotransformations are increasingly replacing chemical routes of synthesis in organic chemistry as a part of ‘green chemistry’. Nitrile metabolizing organisms or enzymes thus has assumed greater significance in all these years to convert nitriles to amides/ acids. The nitrile metabolizing enzymes are widely present in bacteria, fungi and yeasts. Yeasts metabolize nitriles through nitrilase and/or nitrile hydratase and amidase enzymes. Only few yeasts have been reported to possess aldoxime dehydratase. More than sixty nitrile metabolizing yeast strains have been hither to isolated from cyanide treatment bioreactor, fermented foods and soil. Most of the yeasts contain nitrile hydratase-amidase system for metabolizing nitriles. Transformations of nitriles to amides/acids have been carried out with free and immobilized yeast cells. The nitrilases of Torulopsis candida>and Exophiala oligosperma>R1 are enantioselec-tive and regiospecific respectively. Geotrichum>sp. JR1 grows in the presence of 2M acetonitrile and may have potential for application in bioremediation of nitrile contaminated soil/water. The nitrilase of E. oligosperma>R1 being active at low pH (3-6) has shown promise for the hydroxy acids. Immobilized yeast cells hydrolyze some additional nitriles in comparison to free cells. It is expected that more focus in future will be on purification, characterization, cloning, expression and immobilization of nitrile metabolizing

  16. Actin and Endocytosis in Budding Yeast

    Science.gov (United States)

    Goode, Bruce L.; Eskin, Julian A.; Wendland, Beverly

    2015-01-01

    Endocytosis, the process whereby the plasma membrane invaginates to form vesicles, is essential for bringing many substances into the cell and for membrane turnover. The mechanism driving clathrin-mediated endocytosis (CME) involves > 50 different protein components assembling at a single location on the plasma membrane in a temporally ordered and hierarchal pathway. These proteins perform precisely choreographed steps that promote receptor recognition and clustering, membrane remodeling, and force-generating actin-filament assembly and turnover to drive membrane invagination and vesicle scission. Many critical aspects of the CME mechanism are conserved from yeast to mammals and were first elucidated in yeast, demonstrating that it is a powerful system for studying endocytosis. In this review, we describe our current mechanistic understanding of each step in the process of yeast CME, and the essential roles played by actin polymerization at these sites, while providing a historical perspective of how the landscape has changed since the preceding version of the YeastBook was published 17 years ago (1997). Finally, we discuss the key unresolved issues and where future studies might be headed. PMID:25657349

  17. De Novo Biosynthesis of Vanillin in Fission Yeast (Schizosaccharomyces pombe) and Baker's Yeast (Saccharomyces cerevisiae) ▿

    Science.gov (United States)

    Hansen, Esben H.; Møller, Birger Lindberg; Kock, Gertrud R.; Bünner, Camilla M.; Kristensen, Charlotte; Jensen, Ole R.; Okkels, Finn T.; Olsen, Carl E.; Motawia, Mohammed S.; Hansen, Jørgen

    2009-01-01

    Vanillin is one of the world's most important flavor compounds, with a global market of 180 million dollars. Natural vanillin is derived from the cured seed pods of the vanilla orchid (Vanilla planifolia), but most of the world's vanillin is synthesized from petrochemicals or wood pulp lignins. We have established a true de novo biosynthetic pathway for vanillin production from glucose in Schizosaccharomyces pombe, also known as fission yeast or African beer yeast, as well as in baker's yeast, Saccharomyces cerevisiae. Productivities were 65 and 45 mg/liter, after introduction of three and four heterologous genes, respectively. The engineered pathways involve incorporation of 3-dehydroshikimate dehydratase from the dung mold Podospora pauciseta, an aromatic carboxylic acid reductase (ACAR) from a bacterium of the Nocardia genus, and an O-methyltransferase from Homo sapiens. In S. cerevisiae, the ACAR enzyme required activation by phosphopantetheinylation, and this was achieved by coexpression of a Corynebacterium glutamicum phosphopantetheinyl transferase. Prevention of reduction of vanillin to vanillyl alcohol was achieved by knockout of the host alcohol dehydrogenase ADH6. In S. pombe, the biosynthesis was further improved by introduction of an Arabidopsis thaliana family 1 UDP-glycosyltransferase, converting vanillin into vanillin β-d-glucoside, which is not toxic to the yeast cells and thus may be accumulated in larger amounts. These de novo pathways represent the first examples of one-cell microbial generation of these valuable compounds from glucose. S. pombe yeast has not previously been metabolically engineered to produce any valuable, industrially scalable, white biotech commodity. PMID:19286778

  18. Engineering yeast metabolism for production of terpenoids for use as perfume ingredients, pharmaceuticals and biofuels

    DEFF Research Database (Denmark)

    Zhang, Yueping; Nielsen, Jens; Liu, Zihe

    2017-01-01

    of terpenoids that find applications as perfume ingredients, pharmaceuticals and advanced biofuels. In this review, we describe the strategies to rewire the yeast pathway for terpenoid biosynthesis. Recent advances will be discussed together with challenges and perspectives of yeast as a cell factory to produce...

  19. Glycobiology in yeast: production of bio-ative biopolymers and small molecules

    Energy Technology Data Exchange (ETDEWEB)

    Scheller, Henrik [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2014-04-30

    The accomplished goals of the CRADA were the establishment of a yeast strain capable of producing levels of vanillin suitable for commercial production and the identification of novel glycosyltransferases to construct the biosynthetic pathway of a gum Arabic-variant in yeast.

  20. Types of cell death and methods of their detection in yeast Saccharomyces cerevisiae

    NARCIS (Netherlands)

    Wloch-Salamon, D.M.; Bem, A.E.

    2013-01-01

    The occurrence of programmed cell death in unicellular organisms is a subject that arouses great interest of theoreticians and experimental scientists. Already found evolutionarily conserved genes and metabolic pathways confirmed its existence in yeast, protozoa and even bacteria. In the yeast

  1. Genetics of Yeasts

    Science.gov (United States)

    Querol, Amparo; Fernández-Espinar, M. Teresa; Belloch, Carmela

    The use of yeasts in biotechnology processes dates back to ancient days. Before 7000 BC, beer was produced in Sumeria. Wine was made in Assyria in 3500 BC, and ancient Rome had over 250 bakeries, which were making leavened bread by 100 BC. And milk has been made into Kefyr and Koumiss in Asia for many centuries (Demain, Phaff, & Kurtzman, 1999). However, the importance of yeast in the food and beverage industries was only realized about 1860, when their role in food manufacturing became evident.

  2. L-arabinose fermenting yeast

    Science.gov (United States)

    Zhang, Min; Singh, Arjun; Knoshaug, Eric; Franden, Mary Ann; Jarvis, Eric; Suominen, Pirkko

    2010-12-07

    An L-arabinose utilizing yeast strain is provided for the production of ethanol by introducing and expressing bacterial araA, araB and araD genes. L-arabinose transporters are also introduced into the yeast to enhance the uptake of arabinose. The yeast carries additional genomic mutations enabling it to consume L-arabinose, even as the only carbon source, and to produce ethanol. Methods of producing ethanol include utilizing these modified yeast strains. ##STR00001##

  3. The role of mitochondria in yeast programmed cell death

    International Nuclear Information System (INIS)

    Guaragnella, Nicoletta; Ždralević, Maša; Antonacci, Lucia; Passarella, Salvatore; Marra, Ersilia; Giannattasio, Sergio

    2012-01-01

    Mammalian apoptosis and yeast programmed cell death (PCD) share a variety of features including reactive oxygen species production, protease activity and a major role played by mitochondria. In view of this, and of the distinctive characteristics differentiating yeast and multicellular organism PCD, the mitochondrial contribution to cell death in the genetically tractable yeast Saccharomyces cerevisiae has been intensively investigated. In this mini-review we report whether and how yeast mitochondrial function and proteins belonging to oxidative phosphorylation, protein trafficking into and out of mitochondria, and mitochondrial dynamics, play a role in PCD. Since in PCD many processes take place over time, emphasis will be placed on an experimental model based on acetic acid-induced PCD (AA-PCD) which has the unique feature of having been investigated as a function of time. As will be described there are at least two AA-PCD pathways each with a multifaceted role played by mitochondrial components, in particular by cytochrome c.

  4. Yeast Infection during Pregnancy

    Science.gov (United States)

    ... disrupt the pH balance of the vagina. Common yeast infection symptoms include vaginal itching and a white, thick discharge that looks ... and Prevention. http://www.cdc.gov/std/tg2015/candidiasis.htm. Accessed Aug. 27, ... Vagina, Cervix, Toxic Shock Syndrome, Endometritis, and Salpingitis. In: ...

  5. Polysome Profile Analysis - Yeast

    Czech Academy of Sciences Publication Activity Database

    Pospíšek, M.; Valášek, Leoš Shivaya

    2013-01-01

    Roč. 530, č. 2013 (2013), s. 173-181 ISSN 0076-6879 Institutional support: RVO:61388971 Keywords : grow yeast cultures * polysome profile analysis * sucrose density gradient centrifugation Subject RIV: CE - Biochemistry Impact factor: 2.194, year: 2013

  6. Analysis of in vivo binding of yeast heat shock factor to promoter DNA

    African Journals Online (AJOL)

    SERVER

    2008-04-17

    Apr 17, 2008 ... The baker's yeast, Saccharomyces cerevisiae, harbors only a single HSF ... ethanol. The resulting DNA was dissolved in 20 µl TE. PCR. 3% of each .... tolerance oxidant stress, and involve in other biochemical pathways.

  7. Phosphatidylcholine Supply to Peroxisomes of the Yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    Flis, Vid V; Fankl, Ariane; Ramprecht, Claudia; Zellnig, Günther; Leitner, Erich; Hermetter, Albin; Daum, Günther

    2015-01-01

    In the yeast Saccharomyces cerevisiae, phosphatidylcholine (PC), the major phospholipid (PL) of all organelle membranes, is synthesized via two different pathways. Methylation of phosphatidylethanolamine (PE) catalyzed by the methyl transferases Cho2p/Pem1p and Opi3p/Pem2p as well as incorporation of choline through the CDP (cytidine diphosphate)-choline branch of the Kennedy pathway lead to PC formation. To determine the contribution of these two pathways to the supply of PC to peroxisomes (PX), yeast mutants bearing defects in the two pathways were cultivated under peroxisome inducing conditions, i.e. in the presence of oleic acid, and subjected to biochemical and cell biological analyses. Phenotype studies revealed compromised growth of both the cho20Δopi3Δ (mutations in the methylation pathway) and the cki1Δdpl1Δeki1Δ (mutations in the CDP-choline pathway) mutant when grown on oleic acid. Analysis of peroxisomes from the two mutant strains showed that both pathways produce PC for the supply to peroxisomes, although the CDP-choline pathway seemed to contribute with higher efficiency than the methylation pathway. Changes in the peroxisomal lipid pattern of mutants caused by defects in the PC biosynthetic pathways resulted in changes of membrane properties as shown by anisotropy measurements with fluorescent probes. In summary, our data define the origin of peroxisomal PC and demonstrate the importance of PC for peroxisome membrane formation and integrity.

  8. Assigning Quantitative Function to Post-Translational Modifications Reveals Multiple Sites of Phosphorylation That Tune Yeast Pheromone Signaling Output

    Energy Technology Data Exchange (ETDEWEB)

    Pincus, David; Ryan, Christopher J.; Smith, Richard D.; Brent, Roger; Resnekov, Orna; Hakimi, Mohamed Ali

    2013-03-12

    Cell signaling systems transmit information by post-­translationally modifying signaling proteins, often via phosphorylation. While thousands of sites of phosphorylation have been identified in proteomic studies, the vast majority of sites have no known function. Assigning functional roles to the catalog of uncharacterized phosphorylation sites is a key research challenge. Here we present a general approach to address this challenge and apply it to a prototypical signaling pathway, the pheromone response pathway in Saccharomyces cerevisiae. The pheromone pathway includes a mitogen activated protein kinase (MAPK) cascade activated by a G-­protein coupled receptor (GPCR). We used mass spectrometry-based proteomics to identify sites whose phosphorylation changed when the system was active, and evolutionary conservation to assign priority to a list of candidate MAPK regulatory sites. We made targeted alterations in those sites, and measured the effects of the mutations on pheromone pathway output in single cells. Our work identified six new sites that quantitatively tuned system output. We developed simple computational models to find system architectures that recapitulated the quantitative phenotypes of the mutants. Our results identify a number of regulated phosphorylation events that contribute to adjust the input-­output relationship of this model eukaryotic signaling system. We believe this combined approach constitutes a general means not only to reveal modification sites required to turn a pathway on and off, but also those required for more subtle quantitative effects that tune pathway output. Our results further suggest that relatively small quantitative influences from individual regulatory phosphorylation events endow signaling systems with plasticity that evolution may exploit to quantitatively tailor signaling outcomes.

  9. Yeast ecology of Kombucha fermentation.

    Science.gov (United States)

    Teoh, Ai Leng; Heard, Gillian; Cox, Julian

    2004-09-01

    Kombucha is a traditional fermentation of sweetened tea, involving a symbiosis of yeast species and acetic acid bacteria. Despite reports of different yeast species being associated with the fermentation, little is known of the quantitative ecology of yeasts in Kombucha. Using oxytetracycline-supplemented malt extract agar, yeasts were isolated from four commercially available Kombucha products and identified using conventional biochemical and physiological tests. During the fermentation of each of the four products, yeasts were enumerated from both the cellulosic pellicle and liquor of the Kombucha. The number and diversity of species varied between products, but included Brettanomyces bruxellensis, Candida stellata, Schizosaccharomyces pombe, Torulaspora delbrueckii and Zygosaccharomyces bailii. While these yeast species are known to occur in Kombucha, the enumeration of each species present throughout fermentation of each of the four Kombucha cultures demonstrated for the first time the dynamic nature of the yeast ecology. Kombucha fermentation is, in general, initiated by osmotolerant species, succeeded and ultimately dominated by acid-tolerant species.

  10. The yeast osmostress response is carbon source dependent

    DEFF Research Database (Denmark)

    Babazadeh, Roja; Lahtvee, Petri-Jaan; Adiels, Caroline B.

    2017-01-01

    . Remarkably, yeast cells do not accumulate glycerol under these conditions and it appears that trehalose may partly take over the role as compatible solute. The HOG pathway is activated in very much the same way as during growth on glucose and is also required for osmotic adaptation. Slower volume recovery...

  11. Yeast Methylotrophy and Autophagy in a Methanol-Oscillating Environment on Growing Arabidopsis thaliana Leaves

    Science.gov (United States)

    Kawaguchi, Kosuke; Yurimoto, Hiroya; Oku, Masahide; Sakai, Yasuyoshi

    2011-01-01

    The yeast Candida boidinii capable of growth on methanol proliferates and survives on the leaves of Arabidopsis thaliana. The local methanol concentration at the phyllosphere of growing A. thaliana exhibited daily periodicity, and yeast cells responded by altering both the expression of methanol-inducible genes and peroxisome proliferation. Even under these dynamically changing environmental conditions, yeast cells proliferated 3 to 4 times in 11 days. Among the C1-metabolic enzymes, enzymes in the methanol assimilation pathway, but not formaldehyde dissimilation or anti-oxidizing enzymes, were necessary for yeast proliferation at the phyllosphere. Furthermore, both peroxisome assembly and pexophagy, a selective autophagy pathway that degrades peroxisomes, were necessary for phyllospheric proliferation. Thus, the present study sheds light on the life cycle and physiology of yeast in the natural environment at both the molecular and cellular levels. PMID:21966472

  12. Tapping into yeast diversity.

    Science.gov (United States)

    Fay, Justin C

    2012-11-01

    Domesticated organisms demonstrate our capacity to influence wild species but also provide us with the opportunity to understand rapid evolution in the context of substantially altered environments and novel selective pressures. Recent advances in genetics and genomics have brought unprecedented insights into the domestication of many organisms and have opened new avenues for further improvements to be made. Yet, our ability to engineer biological systems is not without limits; genetic manipulation is often quite difficult. The budding yeast, Saccharomyces cerevisiae, is not only one of the most powerful model organisms, but is also the premier producer of fermented foods and beverages around the globe. As a model system, it entertains a hefty workforce dedicated to deciphering its genome and the function it encodes at a rich mechanistic level. As a producer, it is used to make leavened bread, and dozens of different alcoholic beverages, such as beer and wine. Yet, applying the awesome power of yeast genetics to understanding its origins and evolution requires some knowledge of its wild ancestors and the environments from which they were derived. A number of surprisingly diverse lineages of S. cerevisiae from both primeval and secondary forests in China have been discovered by Wang and his colleagues. These lineages substantially expand our knowledge of wild yeast diversity and will be a boon to elucidating the ecology, evolution and domestication of this academic and industrial workhorse.

  13. Dietary glucose regulates yeast consumption in adult Drosophila males

    Directory of Open Access Journals (Sweden)

    Sebastien eLebreton

    2014-12-01

    Full Text Available The adjustment of feeding behavior in response to hunger and satiety contributes to homeostatic regulation in animals. The fruit fly Drosophila melanogaster feeds on yeasts growing on overripe fruit, providing nutrients required for adult survival, reproduction and larval growth. Here, we present data on how the nutritional value of food affects subsequent yeast consumption in Drosophila adult males. After a period of starvation, flies showed intensive yeast consumption. In comparison, flies stopped feeding after having access to a nutritive cornmeal diet. Interestingly, dietary glucose was equally efficient as the complex cornmeal diet. In contrast, flies fed with sucralose, a non-metabolizable sweetener, behaved as if they were starved. The adipokinetic hormone and insulin-like peptides regulate metabolic processes in insects. We did not find any effect of the adipokinetic hormone pathway on this modulation. Instead, the insulin pathway was involved in these changes. Flies lacking the insulin receptor did not respond to nutrient deprivation by increasing yeast consumption. Together these results show the importance of insulin in the regulation of yeast consumption in response to starvation in adult D. melanogaster males.

  14. Dietary glucose regulates yeast consumption in adult Drosophila males.

    Science.gov (United States)

    Lebreton, Sébastien; Witzgall, Peter; Olsson, Marie; Becher, Paul G

    2014-01-01

    The adjustment of feeding behavior in response to hunger and satiety contributes to homeostatic regulation in animals. The fruit fly Drosophila melanogaster feeds on yeasts growing on overripe fruit, providing nutrients required for adult survival, reproduction and larval growth. Here, we present data on how the nutritional value of food affects subsequent yeast consumption in Drosophila adult males. After a period of starvation, flies showed intensive yeast consumption. In comparison, flies stopped feeding after having access to a nutritive cornmeal diet. Interestingly, dietary glucose was equally efficient as the complex cornmeal diet. In contrast, flies fed with sucralose, a non-metabolizable sweetener, behaved as if they were starved. The adipokinetic hormone and insulin-like peptides regulate metabolic processes in insects. We did not find any effect of the adipokinetic hormone pathway on this modulation. Instead, the insulin pathway was involved in these changes. Flies lacking the insulin receptor (InR) did not respond to nutrient deprivation by increasing yeast consumption. Together these results show the importance of insulin in the regulation of yeast consumption in response to starvation in adult D. melanogaster males.

  15. Analysis of the role of the Aspergillus niger aminolevulinic acid synthase (hemA) gene illustrates the difference between regulation of yeast and fungal haem- and sirohaem-dependent pathways

    NARCIS (Netherlands)

    Franken, A.C.; Christien Lokman, B.; Ram, A.F.; Hondel, C.A. van den; Weert, S. de; Punt, P.J.

    2012-01-01

    To increase knowledge on haem biosynthesis in filamentous fungi like Aspergillus niger, pathway-specific gene expression in response to haem and haem intermediates was analysed. This analysis showed that iron, 5′-aminolevulinic acid (ALA) and possibly haem control haem biosynthesis mostly via

  16. Analysis of the role of the A. niger aminolevulinic acid synthase (hemA) gene illustrates the difference between regulation of yeast and fungal heme and siroheme dependent pathways

    NARCIS (Netherlands)

    A.F. Ram; C.A. van den Hondel; Christien Lokman; P.J. Punt; S. de Weert; A. Franken

    2012-01-01

    To increase knowledge on haem biosynthesis in filamentous fungi like Aspergillus niger, pathway-specific gene expression in response to haem and haem intermediates was analysed. This analysis showed that iron, 5'-aminolevulinic acid (ALA) and possibly haem control haem biosynthesis mostly via

  17. Yeast: the soul of beer's aroma--a review of flavour-active esters and higher alcohols produced by the brewing yeast.

    Science.gov (United States)

    Pires, Eduardo J; Teixeira, José A; Brányik, Tomás; Vicente, António A

    2014-03-01

    Among the most important factors influencing beer quality is the presence of well-adjusted amounts of higher alcohols and esters. Thus, a heavy body of literature focuses on these substances and on the parameters influencing their production by the brewing yeast. Additionally, the complex metabolic pathways involved in their synthesis require special attention. More than a century of data, mainly in genetic and proteomic fields, has built up enough information to describe in detail each step in the pathway for the synthesis of higher alcohols and their esters, but there is still place for more. Higher alcohols are formed either by anabolism or catabolism (Ehrlich pathway) of amino acids. Esters are formed by enzymatic condensation of organic acids and alcohols. The current paper reviews the up-to-date knowledge in the pathways involving the synthesis of higher alcohols and esters by brewing yeasts. Fermentation parameters affecting yeast response during biosynthesis of these aromatic substances are also fully reviewed.

  18. Sexual differentiation in fission yeast

    DEFF Research Database (Denmark)

    Egel, R; Nielsen, O; Weilguny, D

    1990-01-01

    The regulation of sexual reproduction in yeast constitutes the highest level of differentiation observed in these unicellular organisms. The various ramifications of this system involve DNA rearrangement, transcriptional control, post-translational modification (such as protein phosphorylation) a......) and receptor/signal processing. A few basic similarities are common to both fission and budding yeasts. The wiring of the regulatory circuitry, however, varies considerably between these divergent yeast groups....

  19. Entropy analysis in yeast DNA

    International Nuclear Information System (INIS)

    Kim, Jongkwang; Kim, Sowun; Lee, Kunsang; Kwon, Younghun

    2009-01-01

    In this article, we investigate the language structure in yeast 16 chromosomes. In order to find it, we use the entropy analysis for codons (or amino acids) of yeast 16 chromosomes, developed in analysis of natural language by Montemurro et al. From the analysis, we can see that there exists a language structure in codons (or amino acids) of yeast 16 chromosomes. Also we find that the grammar structure of amino acids of yeast 16 chromosomes has a deep relationship with secondary structure of protein.

  20. Mapping out starvation responses in yeast by proteomics

    DEFF Research Database (Denmark)

    Rødkær, Steven Vestergaard; Færgeman, Nils J.; Andersen, Jens S.

    2011-01-01

    that are involved in this positive outcome. Based on that, processes like autophagy, lipid turnover and the generation/clearance of reactive oxygen species (ROS) have all been describe to affect life span, either alone, or in a not fully characterized interplay. The baker’s yeast Saccharomyces cerevisae is by now...... the organism with the best characterized proteome and is therefore the organism of choice in many proteomic studies. Additionally, this single-celled organism exhibits many conserved proteins and pathways of higher animals, thus observations in the yeast might reveal important information applying to other...

  1. Generic sorting of raft lipids into secretory vesicles in yeast

    DEFF Research Database (Denmark)

    Surma, Michal A; Klose, Christian; Klemm, Robin W

    2011-01-01

    Previous work has showed that ergosterol and sphingolipids become sorted to secretory vesicles immunoisolated using a chimeric, artificial raft membrane protein as bait. In this study, we have extended this analysis to three populations of secretory vesicles isolated using natural yeast plasma...... a complete lipid overview of the yeast late secretory pathway. We could show that vesicles captured with different baits carry the same cargo and have almost identical lipid compositions; being highly enriched in ergosterol and sphingolipids. This finding indicates that lipid raft sorting is a generic...

  2. Genomics and the making of yeast biodiversity

    NARCIS (Netherlands)

    Hittinger, Chris Todd; Rokas, Antonis; Bai, Feng-Yan; Boekhout, Teun; Gonçalves, Paula; Jeffries, Thomas W; Kominek, Jacek; Lachance, Marc-André; Libkind, Diego; Rosa, Carlos A; Sampaio, José Paulo; Kurtzman, Cletus P

    2015-01-01

    Yeasts are unicellular fungi that do not form fruiting bodies. Although the yeast lifestyle has evolved multiple times, most known species belong to the subphylum Saccharomycotina (syn. Hemiascomycota, hereafter yeasts). This diverse group includes the premier eukaryotic model system, Saccharomyces

  3. Current awareness on yeast.

    Science.gov (United States)

    2002-02-01

    In order to keep subscribers up-to-date with the latest developments in their field, this current awareness service is provided by John Wiley & Sons and contains newly-published material on yeasts. Each bibliography is divided into 10 sections. 1 Books, Reviews & Symposia; 2 General; 3 Biochemistry; 4 Biotechnology; 5 Cell Biology; 6 Gene Expression; 7 Genetics; 8 Physiology; 9 Medical Mycology; 10 Recombinant DNA Technology. Within each section, articles are listed in alphabetical order with respect to author. If, in the preceding period, no publications are located relevant to any one of these headings, that section will be omitted. (3 weeks journals - search completed 5th. Dec. 2001)

  4. Transporter engineering in biomass utilization by yeast.

    Science.gov (United States)

    Hara, Kiyotaka Y; Kobayashi, Jyumpei; Yamada, Ryosuke; Sasaki, Daisuke; Kuriya, Yuki; Hirono-Hara, Yoko; Ishii, Jun; Araki, Michihiro; Kondo, Akihiko

    2017-11-01

    Biomass resources are attractive carbon sources for bioproduction because of their sustainability. Many studies have been performed using biomass resources to produce sugars as carbon sources for cell factories. Expression of biomass hydrolyzing enzymes in cell factories is an important approach for constructing biomass-utilizing bioprocesses because external addition of these enzymes is expensive. In particular, yeasts have been extensively engineered to be cell factories that directly utilize biomass because of their manageable responses to many genetic engineering tools, such as gene expression, deletion and editing. Biomass utilizing bioprocesses have also been developed using these genetic engineering tools to construct metabolic pathways. However, sugar input and product output from these cells are critical factors for improving bioproduction along with biomass utilization and metabolic pathways. Transporters are key components for efficient input and output activities. In this review, we focus on transporter engineering in yeast to enhance bioproduction from biomass resources. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  5. Inheritance of the yeast mitochondrial genome

    DEFF Research Database (Denmark)

    Piskur, Jure

    1994-01-01

    Mitochondrion, extrachromosomal genetics, intergenic sequences, genome size, mitochondrial DNA, petite mutation, yeast......Mitochondrion, extrachromosomal genetics, intergenic sequences, genome size, mitochondrial DNA, petite mutation, yeast...

  6. Yeasts preservation: alternatives for lyophilisation

    NARCIS (Netherlands)

    Nyanga, L.K.; Nout, M.J.R.; Smid, E.J.; Boekhout, T.; Zwietering, M.H.

    2012-01-01

    The aim of the study was to compare the effect of two low-cost, low technology traditional methods for drying starter cultures with standard lyophilisation. Lyophilised yeast cultures and yeast cultures preserved in dry rice cakes and dry plant fibre strands were examined for viable cell counts

  7. Production of biopharmaceutical proteins by yeast: Advances through metabolic engineering

    DEFF Research Database (Denmark)

    Nielsen, Jens

    2013-01-01

    Production of recombinant proteins for use as pharmaceuticals, so-called biopharmaceuticals, is a multi-billion dollar industry. Many different cell factories are used for the production of biopharmaceuticals, but the yeast Saccharomyces cerevisiae is an important cell factory as it is used for p...... production. The involvement of directed metabolic engineering through the integration of tools from genetic engineering, systems biology and mathematical modeling, is also discussed....... by yeast are human serum albumin, hepatitis vaccines and virus like particles used for vaccination against human papillomavirus. Here is given a brief overview of biopharmaceutical production by yeast and it is discussed how the secretory pathway can be engineered to ensure more efficient protein...

  8. Production of Food Grade Yeasts

    Directory of Open Access Journals (Sweden)

    Argyro Bekatorou

    2006-01-01

    Full Text Available Yeasts have been known to humans for thousands of years as they have been used in traditional fermentation processes like wine, beer and bread making. Today, yeasts are also used as alternative sources of high nutritional value proteins, enzymes and vitamins, and have numerous applications in the health food industry as food additives, conditioners and flavouring agents, for the production of microbiology media and extracts, as well as livestock feeds. Modern scientific advances allow the isolation, construction and industrial production of new yeast strains to satisfy the specific demands of the food industry. Types of commercial food grade yeasts, industrial production processes and raw materials are highlighted. Aspects of yeast metabolism, with respect to carbohydrate utilization, nutritional aspects and recent research advances are also discussed.

  9. Evolutionary History of Ascomyceteous Yeasts

    Energy Technology Data Exchange (ETDEWEB)

    Haridas, Sajeet; Riley, Robert; Salamov, Asaf; Goker, Markus; Klenk, Hans-Peter; Kurtzman, Cletus P.; Blackwell, Meredith; Grigoriev, Igor; Jeffries, Thomas W.

    2014-06-06

    Yeasts are important for many industrial and biotechnological processes and show remarkable diversity despite morphological similarities. We have sequenced the genomes of 16 ascomycete yeasts of taxonomic and industrial importance including members of Saccharomycotina and Taphrinomycotina. A comparison of these with several other previously published yeast genomes have added increased confidence to the phylogenetic positions of previously poorly placed species including Saitoella complicata, Babjeviella inositovora and Metschnikowia bicuspidata. Phylogenetic analysis also showed that yeasts with alternative nuclear codon usage where CUG encodes serine instead of leucine are monophyletic within the Saccharomycotina. Most of the yeasts have compact genomes with a large fraction of single exon genes with Lipomyces starkeyi and the previously published Pneumocystis jirovecii being notable exceptions. Intron analysis suggests that early diverging species have more introns. We also observed a large number of unclassified lineage specific non-simple repeats in these genomes.

  10. Reconstitution of an efficient thymidine salvage pathway in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Vernis, L.; Piskur, Jure; Diffley, J.F.X.

    2003-01-01

    The budding yeast Saccharomyces cerevisiae is unable to incorporate exogenous nucleosides into DNA. We have made a number of improvements to existing strategies to reconstitute an efficient thymidine salvage pathway in yeast. We have constructed strains that express both a nucleoside kinase as well...

  11. Systems Biology for Mapping Genotype-Phenotype Relations in Yeast

    KAUST Repository

    Nielsen, Jens

    2016-01-25

    The yeast Saccharomyces cerevisiae is widely used for production of fuels, chemicals, pharmaceuticals and materials. Through metabolic engineering of this yeast a number of novel new industrial processes have been developed over the last 10 years. Besides its wide industrial use, S. cerevisiae serves as an eukaryal model organism, and many systems biology tools have therefore been developed for this organism. Among these genome-scale metabolic models have shown to be most successful as they easy integrate with omics data and at the same time have been shown to have excellent predictive power. Despite our extensive knowledge of yeast metabolism and its regulation we are still facing challenges when we want to engineer complex traits, such as improved tolerance to toxic metabolites like butanol and elevated temperatures or when we want to engineer the highly complex protein secretory pathway. In this presentation it will be demonstrated how we can combine directed evolution with systems biology analysis to identify novel targets for rational design-build-test of yeast strains that have improved phenotypic properties. In this lecture an overview of systems biology of yeast will be presented together with examples of how genome-scale metabolic modeling can be used for prediction of cellular growth at different conditions. Examples will also be given on how adaptive laboratory evolution can be used for identifying targets for improving tolerance towards butanol, increased temperature and low pH and for improving secretion of heterologous proteins.

  12. Mitochondrial fission proteins regulate programmed cell death in yeast.

    Science.gov (United States)

    Fannjiang, Yihru; Cheng, Wen-Chih; Lee, Sarah J; Qi, Bing; Pevsner, Jonathan; McCaffery, J Michael; Hill, R Blake; Basañez, Gorka; Hardwick, J Marie

    2004-11-15

    The possibility that single-cell organisms undergo programmed cell death has been questioned in part because they lack several key components of the mammalian cell death machinery. However, yeast encode a homolog of human Drp1, a mitochondrial fission protein that was shown previously to promote mammalian cell death and the excessive mitochondrial fragmentation characteristic of apoptotic mammalian cells. In support of a primordial origin of programmed cell death involving mitochondria, we found that the Saccharomyces cerevisiae homolog of human Drp1, Dnm1, promotes mitochondrial fragmentation/degradation and cell death following treatment with several death stimuli. Two Dnm1-interacting factors also regulate yeast cell death. The WD40 repeat protein Mdv1/Net2 promotes cell death, consistent with its role in mitochondrial fission. In contrast to its fission function in healthy cells, Fis1 unexpectedly inhibits Dnm1-mediated mitochondrial fission and cysteine protease-dependent cell death in yeast. Furthermore, the ability of yeast Fis1 to inhibit mitochondrial fission and cell death can be functionally replaced by human Bcl-2 and Bcl-xL. Together, these findings indicate that yeast and mammalian cells have a conserved programmed death pathway regulated by a common molecular component, Drp1/Dnm1, that is inhibited by a Bcl-2-like function.

  13. Nuclear Magnetic Resonance Spectroscopy-Based Identification of Yeast.

    Science.gov (United States)

    Himmelreich, Uwe; Sorrell, Tania C; Daniel, Heide-Marie

    2017-01-01

    Rapid and robust high-throughput identification of environmental, industrial, or clinical yeast isolates is important whenever relatively large numbers of samples need to be processed in a cost-efficient way. Nuclear magnetic resonance (NMR) spectroscopy generates complex data based on metabolite profiles, chemical composition and possibly on medium consumption, which can not only be used for the assessment of metabolic pathways but also for accurate identification of yeast down to the subspecies level. Initial results on NMR based yeast identification where comparable with conventional and DNA-based identification. Potential advantages of NMR spectroscopy in mycological laboratories include not only accurate identification but also the potential of automated sample delivery, automated analysis using computer-based methods, rapid turnaround time, high throughput, and low running costs.We describe here the sample preparation, data acquisition and analysis for NMR-based yeast identification. In addition, a roadmap for the development of classification strategies is given that will result in the acquisition of a database and analysis algorithms for yeast identification in different environments.

  14. Engineering yeast metabolism for production of terpenoids for use as perfume ingredients, pharmaceuticals and biofuels.

    Science.gov (United States)

    Zhang, Yueping; Nielsen, Jens; Liu, Zihe

    2017-12-01

    Terpenoids represent a large class of natural products with significant commercial applications. These chemicals are currently mainly obtained through extraction from plants and microbes or through chemical synthesis. However, these sources often face challenges of unsustainability and low productivity. In order to address these issues, Escherichia coli and yeast have been metabolic engineered to produce non-native terpenoids. With recent reports of engineering yeast metabolism to produce several terpenoids at high yields, it has become possible to establish commercial yeast production of terpenoids that find applications as perfume ingredients, pharmaceuticals and advanced biofuels. In this review, we describe the strategies to rewire the yeast pathway for terpenoid biosynthesis. Recent advances will be discussed together with challenges and perspectives of yeast as a cell factory to produce different terpenoids. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  15. Genetic study on yeast

    International Nuclear Information System (INIS)

    Mortimer, R.K.

    1981-01-01

    Research during the past year has moved ahead on several fronts. A major compilation of all the genetic mapping data for the yeast Saccharomyces cerevisiae has been completed. The map describes the location of over 300 genes on 17 chromosomes. A report on this work will appear in Microbiological Reviews in December 1980. Recombinant DNA procedures have been introduced into the experiments and RAD52 (one of the genes involved in recombination and repair damage), has been successfully cloned. This clone will be used to determine the gene product. Diploid cells homozygous for RAD52 have exceptionally high frequencies of mitotic loss of chromosomes. This loss is stimulated by ionizing radiation. This effect is a very significant finding. The effect has also been seen with certain other RAD mutants

  16. Lager Yeast Comes of Age

    Science.gov (United States)

    2014-01-01

    Alcoholic fermentations have accompanied human civilizations throughout our history. Lager yeasts have a several-century-long tradition of providing fresh beer with clean taste. The yeast strains used for lager beer fermentation have long been recognized as hybrids between two Saccharomyces species. We summarize the initial findings on this hybrid nature, the genomics/transcriptomics of lager yeasts, and established targets of strain improvements. Next-generation sequencing has provided fast access to yeast genomes. Its use in population genomics has uncovered many more hybridization events within Saccharomyces species, so that lager yeast hybrids are no longer the exception from the rule. These findings have led us to propose network evolution within Saccharomyces species. This “web of life” recognizes the ability of closely related species to exchange DNA and thus drain from a combined gene pool rather than be limited to a gene pool restricted by speciation. Within the domesticated lager yeasts, two groups, the Saaz and Frohberg groups, can be distinguished based on fermentation characteristics. Recent evidence suggests that these groups share an evolutionary history. We thus propose to refer to the Saaz group as Saccharomyces carlsbergensis and to the Frohberg group as Saccharomyces pastorianus based on their distinct genomes. New insight into the hybrid nature of lager yeast will provide novel directions for future strain improvement. PMID:25084862

  17. Interaction Between Yeasts and Zinc

    Science.gov (United States)

    Nicola, Raffaele De; Walker, Graeme

    Zinc is an essential trace element in biological systems. For example, it acts as a cellular membrane stabiliser, plays a critical role in gene expression and genome modification and activates nearly 300 enzymes, including alcohol dehydrogenase. The present chapter will be focused on the influence of zinc on cell physiology of industrial yeast strains of Saccharomyces cerevisiae, with special regard to the uptake and subsequent utilisation of this metal. Zinc uptake by yeast is metabolism-dependent, with most of the available zinc translocated very quickly into the vacuole. At cell division, zinc is distributed from mother to daughter cells and this effectively lowers the individual cellular zinc concentration, which may become zinc depleted at the onset of the fermentation. Zinc influences yeast fermentative performance and examples will be provided relating to brewing and wine fermentations. Industrial yeasts are subjected to several stresses that may impair fermentation performance. Such stresses may also impact on yeast cell zinc homeostasis. This chapter will discuss the practical implications for the correct management of zinc bioavailability for yeast-based biotechnologies aimed at improving yeast growth, viability, fermentation performance and resistance to environmental stresses

  18. Apoptosis-like yeast cell death in response to DNA damage and replication defects

    Energy Technology Data Exchange (ETDEWEB)

    Burhans, William C.; Weinberger, Martin; Marchetti, Maria A.; Ramachandran, Lakshmi; D' Urso, Gennaro; Huberman, Joel A

    2003-11-27

    In budding (Saccharomyces cerevisiae) and fission (Schizosaccharomyces pombe) yeast and other unicellular organisms, DNA damage and other stimuli can induce cell death resembling apoptosis in metazoans, including the activation of a recently discovered caspase-like molecule in budding yeast. Induction of apoptotic-like cell death in yeasts requires homologues of cell cycle checkpoint proteins that are often required for apoptosis in metazoan cells. Here, we summarize these findings and our unpublished results which show that an important component of metazoan apoptosis recently detected in budding yeast - reactive oxygen species (ROS) - can also be detected in fission yeast undergoing an apoptotic-like cell death. ROS were detected in fission and budding yeast cells bearing conditional mutations in genes encoding DNA replication initiation proteins and in fission yeast cells with mutations that deregulate cyclin-dependent kinases (CDKs). These mutations may cause DNA damage by permitting entry of cells into S phase with a reduced number of replication forks and/or passage through mitosis with incompletely replicated chromosomes. This may be relevant to the frequent requirement for elevated CDK activity in mammalian apoptosis, and to the recent discovery that the initiation protein Cdc6 is destroyed during apoptosis in mammals and in budding yeast cells exposed to lethal levels of DNA damage. Our data indicate that connections between apoptosis-like cell death and DNA replication or CDK activity are complex. Some apoptosis-like pathways require checkpoint proteins, others are inhibited by them, and others are independent of them. This complexity resembles that of apoptotic pathways in mammalian cells, which are frequently deregulated in cancer. The greater genetic tractability of yeasts should help to delineate these complex pathways and their relationships to cancer and to the effects of apoptosis-inducing drugs that inhibit DNA replication.

  19. Apoptosis-like yeast cell death in response to DNA damage and replication defects

    International Nuclear Information System (INIS)

    Burhans, William C.; Weinberger, Martin; Marchetti, Maria A.; Ramachandran, Lakshmi; D'Urso, Gennaro; Huberman, Joel A.

    2003-01-01

    In budding (Saccharomyces cerevisiae) and fission (Schizosaccharomyces pombe) yeast and other unicellular organisms, DNA damage and other stimuli can induce cell death resembling apoptosis in metazoans, including the activation of a recently discovered caspase-like molecule in budding yeast. Induction of apoptotic-like cell death in yeasts requires homologues of cell cycle checkpoint proteins that are often required for apoptosis in metazoan cells. Here, we summarize these findings and our unpublished results which show that an important component of metazoan apoptosis recently detected in budding yeast - reactive oxygen species (ROS) - can also be detected in fission yeast undergoing an apoptotic-like cell death. ROS were detected in fission and budding yeast cells bearing conditional mutations in genes encoding DNA replication initiation proteins and in fission yeast cells with mutations that deregulate cyclin-dependent kinases (CDKs). These mutations may cause DNA damage by permitting entry of cells into S phase with a reduced number of replication forks and/or passage through mitosis with incompletely replicated chromosomes. This may be relevant to the frequent requirement for elevated CDK activity in mammalian apoptosis, and to the recent discovery that the initiation protein Cdc6 is destroyed during apoptosis in mammals and in budding yeast cells exposed to lethal levels of DNA damage. Our data indicate that connections between apoptosis-like cell death and DNA replication or CDK activity are complex. Some apoptosis-like pathways require checkpoint proteins, others are inhibited by them, and others are independent of them. This complexity resembles that of apoptotic pathways in mammalian cells, which are frequently deregulated in cancer. The greater genetic tractability of yeasts should help to delineate these complex pathways and their relationships to cancer and to the effects of apoptosis-inducing drugs that inhibit DNA replication

  20. Yeasts preservation: alternatives for lyophilisation

    OpenAIRE

    Nyanga, Loveness K.; Nout, Martinus J. R.; Smid, Eddy J.; Boekhout, Teun; Zwietering, Marcel H.

    2012-01-01

    The aim of the study was to compare the effect of two low-cost, low technology traditional methods for drying starter cultures with standard lyophilisation. Lyophilised yeast cultures and yeast cultures preserved in dry rice cakes and dry plant fibre strands were examined for viable cell counts during 6 months storage at 4 and 25 °C. None of the yeast cultures showed a significant loss in viable cell count during 6 months of storage at 4 °C upon lyophilisation and preservation in dry rice cak...

  1. [Distiller Yeasts Producing Antibacterial Peptides].

    Science.gov (United States)

    Klyachko, E V; Morozkina, E V; Zaitchik, B Ts; Benevolensky, S V

    2015-01-01

    A new method of controlling lactic acid bacteria contamination was developed with the use of recombinant Saccharomyces cerevisiae strains producing antibacterial peptides. Genes encoding the antibacterial peptides pediocin and plantaricin with codons preferable for S. cerevisiae were synthesized, and a system was constructed for their secretory expression. Recombinant S. cerevisiae strains producing antibacterial peptides effectively inhibit the growth of Lactobacillus sakei, Pediacoccus pentasaceus, Pediacoccus acidilactici, etc. The application of distiller yeasts producing antibacterial peptides enhances the ethanol yield in cases of bacterial contamination. Recombinant yeasts producing the antibacterial peptides pediocin and plantaricin can successfully substitute the available industrial yeast strains upon ethanol production.

  2. Yeast synthetic biology for high-value metabolites.

    Science.gov (United States)

    Dai, Zhubo; Liu, Yi; Guo, Juan; Huang, Luqi; Zhang, Xueli

    2015-02-01

    Traditionally, high-value metabolites have been produced through direct extraction from natural biological sources which are inefficient, given the low abundance of these compounds. On the other hand, these high-value metabolites are usually difficult to be synthesized chemically, due to their complex structures. In the last few years, the discovery of genes involved in the synthetic pathways of these metabolites, combined with advances in synthetic biology tools, has allowed the construction of increasing numbers of yeast cell factories for production of these metabolites from renewable biomass. This review summarizes recent advances in synthetic biology in terms of the use of yeasts as microbial hosts for the identification of the pathways involved in the synthesis, as well as for the production of high-value metabolites. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permission@oup.com.

  3. Implication of Ca2+ in the Regulation of Replicative Life Span of Budding Yeast*

    OpenAIRE

    Tsubakiyama, Ryohei; Mizunuma, Masaki; Gengyo, Anri; Yamamoto, Josuke; Kume, Kazunori; Miyakawa, Tokichi; Hirata, Dai

    2011-01-01

    In eukaryotic cells, Ca2+-triggered signaling pathways are used to regulate a wide variety of cellular processes. Calcineurin, a highly conserved Ca2+/calmodulin-dependent protein phosphatase, plays key roles in the regulation of diverse biological processes in organisms ranging from yeast to humans. We isolated a mutant of the SIR3 gene, implicated in the regulation of life span, as a suppressor of the Ca2+ sensitivity of zds1Δ cells in the budding yeast Saccharomyces cerevisiae. Therefore, ...

  4. How does yeast respond to pressure?

    Directory of Open Access Journals (Sweden)

    Fernandes P.M.B.

    2005-01-01

    Full Text Available The brewing and baking yeast Saccharomyces cerevisiae has been used as a model for stress response studies of eukaryotic cells. In this review we focus on the effect of high hydrostatic pressure (HHP on S. cerevisiae. HHP exerts a broad effect on yeast cells characteristic of common stresses, mainly associated with protein alteration and lipid bilayer phase transition. Like most stresses, pressure induces cell cycle arrest. Below 50 MPa (500 atm yeast cell morphology is unaffected whereas above 220 MPa wild-type cells are killed. S. cerevisiae cells can acquire barotolerance if they are pretreated with a sublethal stress due to temperature, ethanol, hydrogen peroxide, or pressure. Nevertheless, pressure only leads to protection against severe stress if, after pressure pretreatment, the cells are also re-incubated at room pressure. We attribute this effect to the inhibition of the protein synthesis apparatus under HHP. The global genome expression analysis of S. cerevisiae cells submitted to HHP revealed a stress response profile. The majority of the up-regulated genes are involved in stress defense and carbohydrate metabolism while most repressed genes belong to the cell cycle progression and protein synthesis categories. However, the signaling pathway involved in the pressure response is still to be elucidated. Nitric oxide, a signaling molecule involved in the regulation of a large number of cellular functions, confers baroprotection. Furthermore, S. cerevisiae cells in the early exponential phase submitted to 50-MPa pressure show induction of the expression level of the nitric oxide synthase inducible isoform. As pressure becomes an important biotechnological tool, studies concerning this kind of stress in microorganisms are imperative.

  5. Population FBA predicts metabolic phenotypes in yeast.

    Directory of Open Access Journals (Sweden)

    Piyush Labhsetwar

    2017-09-01

    Full Text Available Using protein counts sampled from single cell proteomics distributions to constrain fluxes through a genome-scale model of metabolism, Population flux balance analysis (Population FBA successfully described metabolic heterogeneity in a population of independent Escherichia coli cells growing in a defined medium. We extend the methodology to account for correlations in protein expression arising from the co-regulation of genes and apply it to study the growth of independent Saccharomyces cerevisiae cells in two different growth media. We find the partitioning of flux between fermentation and respiration predicted by our model agrees with recent 13C fluxomics experiments, and that our model largely recovers the Crabtree effect (the experimentally known bias among certain yeast species toward fermentation with the production of ethanol even in the presence of oxygen, while FBA without proteomics constraints predicts respirative metabolism almost exclusively. The comparisons to the 13C study showed improvement upon inclusion of the correlations and motivated a technique to systematically identify inconsistent kinetic parameters in the literature. The minor secretion fluxes for glycerol and acetate are underestimated by our method, which indicate a need for further refinements to the metabolic model. For yeast cells grown in synthetic defined (SD medium, the calculated broad distribution of growth rates matches experimental observations from single cell studies, and we characterize several metabolic phenotypes within our modeled populations that make use of diverse pathways. Fast growing yeast cells are predicted to perform significant amount of respiration, use serine-glycine cycle and produce ethanol in mitochondria as opposed to slow growing cells. We use a genetic algorithm to determine the proteomics constraints necessary to reproduce the growth rate distributions seen experimentally. We find that a core set of 51 constraints are essential but

  6. Improved vanillin production in baker's yeast through in silico design

    DEFF Research Database (Denmark)

    Brochado, Ana Rita; Matos, Cláudia; Møller, Birger L.

    2010-01-01

    Background: Vanillin is one of the most widely used flavouring agents, originally obtained from cured seed pods of the vanilla orchid Vanilla planifolia. Currently vanillin is mostly produced via chemical synthesis. A de novo synthetic pathway for heterologous vanillin production from glucose has...... recently been implemented in baker's yeast, Saccharamyces cerevisiae. In this study we aimed at engineering this vanillin cell factory towards improved productivity and thereby at developing an attractive alternative to chemical synthesis. Results: Expression of a glycosyltransferase from Arabidopsis...

  7. Yeast strains and methods of use thereof

    OpenAIRE

    Goddard, Matthew Robert; Gardner, Richard Clague; Anfang, Nicole

    2013-01-01

    The present invention relates to yeast strains and, in particular, to yeast stains for use in fermentation processes. The invention also relates to methods of fermentation using the yeast strains of the invention either alone or in combination with other yeast strains. The invention thither relates to methods for the selection of yeast strains suitable for fermentation cultures by screening for various metabolic products and the use of specific nutrient sources.

  8. Biotechnical Microbiology, yeast and bacteria

    DEFF Research Database (Denmark)

    Villadsen, Ingrid Stampe

    1999-01-01

    This section contains the following single lecture notes: Eukaryotic Cell Biology. Kingdom Fungi. Cell Division. Meiosis and Recombination. Genetics of Yeast. Organisation of the Chromosome. Organization and genetics of the mitochondrial Geneme. Regulatio of Gene Expression. Intracellular Compart...

  9. The flavoprotein Tah18-dependent NO synthesis confers high-temperature stress tolerance on yeast cells

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, Akira; Kawahara, Nobuhiro [Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan); Takagi, Hiroshi, E-mail: hiro@bs.naist.jp [Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan)

    2013-01-04

    Highlights: Black-Right-Pointing-Pointer NO is produced from L-arginine in response to elevated temperature in yeast. Black-Right-Pointing-Pointer Tah18 was first identified as the yeast protein involved in NO synthesis. Black-Right-Pointing-Pointer Tah18-dependent NO synthesis confers tolerance to high-temperature on yeast cells. -- Abstract: Nitric oxide (NO) is a ubiquitous signaling molecule involved in the regulation of a large number of cellular functions. In the unicellular eukaryote yeast, NO may be involved in stress response pathways, but its role is poorly understood due to the lack of mammalian NO synthase (NOS) orthologues. Previously, we have proposed the oxidative stress-induced L-arginine synthesis and its physiological role under stress conditions in yeast Saccharomyces cerevisiae. Here, our experimental results indicated that increased conversion of L-proline into L-arginine led to NO production in response to elevated temperature. We also showed that the flavoprotein Tah18, which was previously reported to transfer electrons to the Fe-S cluster protein Dre2, was involved in NO synthesis in yeast. Gene knockdown analysis demonstrated that Tah18-dependent NO synthesis confers high-temperature stress tolerance on yeast cells. As it appears that such a unique cell protection mechanism is specific to yeasts and fungi, it represents a promising target for antifungal activity.

  10. The flavoprotein Tah18-dependent NO synthesis confers high-temperature stress tolerance on yeast cells

    International Nuclear Information System (INIS)

    Nishimura, Akira; Kawahara, Nobuhiro; Takagi, Hiroshi

    2013-01-01

    Highlights: ► NO is produced from L-arginine in response to elevated temperature in yeast. ► Tah18 was first identified as the yeast protein involved in NO synthesis. ► Tah18-dependent NO synthesis confers tolerance to high-temperature on yeast cells. -- Abstract: Nitric oxide (NO) is a ubiquitous signaling molecule involved in the regulation of a large number of cellular functions. In the unicellular eukaryote yeast, NO may be involved in stress response pathways, but its role is poorly understood due to the lack of mammalian NO synthase (NOS) orthologues. Previously, we have proposed the oxidative stress-induced L-arginine synthesis and its physiological role under stress conditions in yeast Saccharomyces cerevisiae. Here, our experimental results indicated that increased conversion of L-proline into L-arginine led to NO production in response to elevated temperature. We also showed that the flavoprotein Tah18, which was previously reported to transfer electrons to the Fe–S cluster protein Dre2, was involved in NO synthesis in yeast. Gene knockdown analysis demonstrated that Tah18-dependent NO synthesis confers high-temperature stress tolerance on yeast cells. As it appears that such a unique cell protection mechanism is specific to yeasts and fungi, it represents a promising target for antifungal activity.

  11. Structural investigations of yeast mannans

    International Nuclear Information System (INIS)

    Rademacher, K.H.

    1983-01-01

    Cell wall mannans were isolated from 8 different Candida species and separated in oligosaccharides by partial acetolysis. After gel chromatography specific acetolysis patterns were obtained. The 13 C NMR spectra of mannans and oligosaccharides were recorded. Signals at delta = 93.1 - 105.4 were assigned to certain chemical structures. Both the spectral patterns and the acetolysis patterns of the yeast mannans can be used for the discrimination of related yeasts. (author)

  12. Methods to Measure Lipophagy in Yeast.

    Science.gov (United States)

    Cristobal-Sarramian, A; Radulovic, M; Kohlwein, S D

    2017-01-01

    Maintenance of cellular and organismal lipid homeostasis is critical for life, and any deviation from a balanced equilibrium between fat uptake and degradation may have deleterious consequences, resulting in severe lipid-associated disorders. Excess fat is typically stored in cytoplasmic organelles termed "lipid droplets" (LDs); to adjust for a constantly fluctuating supply of and demand for cellular fat, these organelles are metabolically highly dynamic and subject to multiple levels of regulation. In addition to a well-described cytosolic lipid degradation pathway, recent evidence underscores the importance of "lipophagy" in cellular lipid homeostasis, i.e., the degradation of LD by autophagy in the lysosome/vacuole. Pioneering work in yeast mutant models has unveiled the requirement of key components of the autophagy machinery, providing evidence for a highly conserved process of lipophagy from yeast to man. However, further work is required to unveil the intricate metabolic interaction between LD metabolism and autophagy to sustain membrane homeostasis and cellular survival. © 2017 Elsevier Inc. All rights reserved.

  13. Oral yeast colonization throughout pregnancy.

    Science.gov (United States)

    Rio, R; Simões-Silva, L; Garro, S; Silva, M-J; Azevedo, Á; Sampaio-Maia, B

    2017-03-01

    Recent studies suggest that placenta may harbour a unique microbiome that may have origin in maternal oral microbiome. Although the major physiological and hormonal adjustments observed in pregnant women lead to biochemical and microbiological modifications of the oral environment, very few studies evaluated the changes suffered by the oral microbiota throughout pregnancy. So, the aim of our study was to evaluate oral yeast colonization throughout pregnancy and to compare it with non-pregnant women. The oral yeast colonization was assessed in saliva of 30 pregnant and non-pregnant women longitudinally over a 6-months period. Demographic information was collected, a non-invasive intra-oral examination was performed and saliva flow and pH were determined. Pregnant and non-pregnant groups were similar regarding age and level of education. Saliva flow rate did not differ, but saliva pH was lower in pregnant than in non-pregnant women. Oral yeast prevalence was higher in pregnant than in non-pregnant women, either in the first or in the third trimester, but did not attain statistical significance. In individuals colonized with yeast, the total yeast quantification (Log10CFU/mL) increase from the 1st to the 3rd trimester in pregnant women, but not in non-pregnant women. Pregnancy may favour oral yeast growth that may be associated with an acidic oral environment.

  14. Biotechnological Applications of Dimorphic Yeasts

    Science.gov (United States)

    Doiphode, N.; Joshi, C.; Ghormade, V.; Deshpande, M. V.

    The dimorphic yeasts have the equilibrium between spherical growth (budding) and polarized (hyphal or pseudohyphal tip elongation) which can be triggered by change in the environmental conditions. The reversible growth phenomenon has made dimorphic yeasts as an useful model to understand fungal evolution and fungal differentiation, in general. In nature dimorphism is clearly evident in plant and animal fungal pathogens, which survive and most importantly proliferate in the respective hosts. However, number of organisms with no known pathogenic behaviour also show such a transition, which can be exploited for the technological applications due to their different biochemical make up under different morphologies. For instance, chitin and chitosan production using dimorphic Saccharomyces, Mucor, Rhizopus and Benjaminiella, oil degradation and biotransformation with yeast-form of Yarrowia species, bioremediation of organic pollutants, exopolysac-charide production by yeast-phase of Aureobasidium pullulans, to name a few. Myrothecium verrucaria can be used for seed dressing in its yeast form and it produces a mycolytic enzyme complex in its hyphal-form for the biocontrol of fungal pathogens, while Beauveria bassiana and other entomopathogens kill the insect pest by producing yeast- like cells in the insect body. The form-specific expression of protease, chitinase, lipase, ornithine decarboxylase, glutamate dehydrogenases, etc. make Benjaminiella poitrasii, Basidiobolus sp., and Mucor rouxii strains important in bioremediation, nanobiotechnology, fungal evolution and other areas.

  15. Indole-3-Acetic Acid-Producing Yeasts in the Phyllosphere of the Carnivorous Plant Drosera indica L

    Science.gov (United States)

    Shin, Li-Ying; Wei, Jyuan-Yu; Fu, Shih-Feng; Chou, Jui-Yu

    2014-01-01

    Yeasts are widely distributed in nature and exist in association with other microorganisms as normal inhabitants of soil, vegetation, and aqueous environments. In this study, 12 yeast strains were enriched and isolated from leaf samples of the carnivorous plant Drosera indica L., which is currently threatened because of restricted habitats and use in herbal industries. According to similarities in large subunit and small subunit ribosomal RNA gene sequences, we identified 2 yeast species in 2 genera of the phylum Ascomycota, and 5 yeast species in 5 genera of the phylum Basidiomycota. All of the isolated yeasts produced indole-3-acetic acid (IAA) when cultivated in YPD broth supplemented with 0.1% L-tryptophan. Growth conditions, such as the pH and temperature of the medium, influenced yeast IAA production. Our results also suggested the existence of a tryptophan-independent IAA biosynthetic pathway. We evaluated the effects of various concentrations of exogenous IAA on yeast growth and observed that IAA produced by wild yeasts modifies auxin-inducible gene expression in Arabidopsis. Our data suggest that yeasts can promote plant growth and support ongoing prospecting of yeast strains for inclusion into biofertilizer for sustainable agriculture. PMID:25464336

  16. Yeast ribosomal proteins

    International Nuclear Information System (INIS)

    Otaka, E.; Kobata, K.

    1978-01-01

    The cytoplasmic 80s ribosomal proteins from the cells of yeast Saccharomyces cerevisiae were analyzed by SDS two-dimensional polyacrylamide gel electrophoresis. Seventyfour proteins were identified and consecutively numbered from 1 to 74. Upon oxidation of the 80s proteins with performic acid, ten proteins (no. 15, 20, 35, 40, 44, 46, 49, 51, 54 and 55) were dislocated on the gel without change of the total number of protein spots. Five proteins (no. 8, 14, 16, 36 and 74) were phosphorylated in vivo as seen in 32 P-labelling experiments. The large and small subunits separated in low magnesium medium were analyzed by the above gel electrophoresis. At least forty-five and twenty-eight proteins were assumed to be in the large and small subunits, respectively. All proteins found in the 80s ribosomes, except for no. 3, were detected in either subunit without appearance of new spots. The acidic protein no. 3 seems to be lost during subunit dissociation. (orig.) [de

  17. Metabolic regulation of yeast

    Science.gov (United States)

    Fiechter, A.

    1982-12-01

    Metabolic regulation which is based on endogeneous and exogeneous process variables which may act constantly or time dependently on the living cell is discussed. The observed phenomena of the regulation are the result of physical, chemical, and biological parameters. These parameters are identified. Ethanol is accumulated as an intermediate product and the synthesis of biomass is reduced. This regulatory effect of glucose is used for the aerobic production of ethanol. Very high production rates are thereby obtained. Understanding of the regulation mechanism of the glucose effect has improved. In addition to catabolite repression, several other mechanisms of enzyme regulation have been described, that are mostly governed by exogeneous factors. Glucose also affects the control of respiration in a third class of yeasts which are unable to make use of ethanol as a substrate for growth. This is due to the lack of any anaplerotic activity. As a consequence, diauxic growth behavior is reduced to a one-stage growth with a drastically reduced cell yield. The pulse chemostat technique, a systematic approach for medium design is developed and medium supplements that are essential for metabolic control are identified.

  18. Trehalose-6-phosphate synthase and stabilization of yeast glycolysis

    DEFF Research Database (Denmark)

    Fraenkel, Dan; Nielsen, Jens

    2016-01-01

    ‘Lost in transition: Startup of glycolysis yields subpopulations of nongrowing cells…’ (‘LIT’, van Heerden et al. 2014) is a massive paper from groups in Amsterdam and Delft, which deals with broad issues in metabolism and cell heterogeneity, as addressed for the predominant metabolic pathway......, glycolysis, in the context of a long studied but incompletely understood yeast mutant which is impaired in use of glucose without evident direct defects in the pathway. The primary approach is the quite original one of predicting, for the mutant, the dynamics of metabolism upon glucose addition, based...

  19. Engineering yeast for high-level production of stilbenoid antioxidants

    DEFF Research Database (Denmark)

    Li, Mingji; Schneider, Konstantin; Kristensen, Mette

    2016-01-01

    engineered the yeast Saccharomyces cerevisiae for production of stilbenoids on a simple mineral medium typically used for industrial production. We applied a pull-push-block strain engineering strategy that included overexpression of the resveratrol biosynthesis pathway, optimization of the electron transfer...... to the cytochrome P450 monooxygenase, increase of the precursors supply, and decrease of the pathway intermediates degradation. Fed-batch fermentation of the final strain resulted in a final titer of 800 mg l(-1) resveratrol, which is by far the highest titer reported to date for production of resveratrol from...

  20. Sporulation in the Budding Yeast Saccharomyces cerevisiae

    Science.gov (United States)

    Neiman, Aaron M.

    2011-01-01

    In response to nitrogen starvation in the presence of a poor carbon source, diploid cells of the yeast Saccharomyces cerevisiae undergo meiosis and package the haploid nuclei produced in meiosis into spores. The formation of spores requires an unusual cell division event in which daughter cells are formed within the cytoplasm of the mother cell. This process involves the de novo generation of two different cellular structures: novel membrane compartments within the cell cytoplasm that give rise to the spore plasma membrane and an extensive spore wall that protects the spore from environmental insults. This article summarizes what is known about the molecular mechanisms controlling spore assembly with particular attention to how constitutive cellular functions are modified to create novel behaviors during this developmental process. Key regulatory points on the sporulation pathway are also discussed as well as the possible role of sporulation in the natural ecology of S. cerevisiae. PMID:22084423

  1. Homocysteine regulates fatty acid and lipid metabolism in yeast.

    Science.gov (United States)

    Visram, Myriam; Radulovic, Maja; Steiner, Sabine; Malanovic, Nermina; Eichmann, Thomas O; Wolinski, Heimo; Rechberger, Gerald N; Tehlivets, Oksana

    2018-04-13

    S -Adenosyl-l-homocysteine hydrolase (AdoHcy hydrolase; Sah1 in yeast/AHCY in mammals) degrades AdoHcy, a by-product and strong product inhibitor of S -adenosyl-l-methionine (AdoMet)-dependent methylation reactions, to adenosine and homocysteine (Hcy). This reaction is reversible, so any elevation of Hcy levels, such as in hyperhomocysteinemia (HHcy), drives the formation of AdoHcy, with detrimental consequences for cellular methylation reactions. HHcy, a pathological condition linked to cardiovascular and neurological disorders, as well as fatty liver among others, is associated with a deregulation of lipid metabolism. Here, we developed a yeast model of HHcy to identify mechanisms that dysregulate lipid metabolism. Hcy supplementation to wildtype cells up-regulated cellular fatty acid and triacylglycerol content and induced a shift in fatty acid composition, similar to changes observed in mutants lacking Sah1. Expression of the irreversible bacterial pathway for AdoHcy degradation in yeast allowed us to dissect the impact of AdoHcy accumulation on lipid metabolism from the impact of elevated Hcy. Expression of this pathway fully suppressed the growth deficit of sah1 mutants as well as the deregulation of lipid metabolism in both the sah1 mutant and Hcy-exposed wildtype, showing that AdoHcy accumulation mediates the deregulation of lipid metabolism in response to elevated Hcy in yeast. Furthermore, Hcy supplementation in yeast led to increased resistance to cerulenin, an inhibitor of fatty acid synthase, as well as to a concomitant decline of condensing enzymes involved in very long-chain fatty acid synthesis, in line with the observed shift in fatty acid content and composition. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

  2. Cadmium, ATPase-P, yeast. From transport to toxicity

    International Nuclear Information System (INIS)

    Gardarin, Aurelie

    2007-01-01

    Two projects has been developed during my PhD. One consisting in the functional study of CadA, the Cd 2+ -ATPase from Listeria monocytogenes, the other one was focused on the toxicity of cadmium and the associated response of the yeast Saccharomyces cerevisiae. This two studies used a a phenotype of sensitivity to cadmium induced by CadA expression in yeast. This phenotype was used as a screening tool to identify essential amino acids of Cd transport by CadA and to study cadmium toxicity and the corresponding yeast cellular response. CadA actively transports Cd using ATP hydrolysis as energy source. Directed mutagenesis of the membranous polar, sulphur and charged amino-acids revealed that Cd transport pathway implied four transmembrane segments (Tm) and more precisely the cysteine C 354 , C 356 and proline P 355 of the CPC motif located in Tm6, aspartate D 692 in Tm8, glutamate E 164 in Tm4 and methionine M 149 in Tm5. From our studies, 2 Cd ions would be translocated for each hydrolysis ATP. Expression of CadA in the yeast Saccharomyces cerevisiae induces an hypersensitivity to Cd. A wild type cell can grow up to 100 μm cadmium whereas CadA expressing yeast cannot grow with 1 μm cadmium in the culture medium. This cadmium sensitivity was due to the localisation of CadA in the endoplasmic reticulum membrane. Transport of cadmium in this compartment produces an accumulation of mis-folded proteins that induces the Unfolded Protein Response (UPR). As UPR also occurs in a wild type yeast exposed to low Cd concentration, one can point out endoplasmic reticulum as a extremely sensitive cellular compartment. UPR also appears as an early response to Cd as it happens far before any visible signs of toxicity. (author) [fr

  3. Yeast Flocculation—Sedimentation and Flotation

    Directory of Open Access Journals (Sweden)

    Graham G. Stewart

    2018-04-01

    Full Text Available Unlike most fermentation alcohol beverage production processes, brewers recycle their yeast. This is achieved by employing a yeast culture’s: flocculation, adhesion, sedimentation, flotation, and cropping characteristics. As a consequence of yeast recycling, the quality of the cropped yeast culture’s characteristics is critical. However, the other major function of brewer’s yeast is to metabolise wort into ethanol, carbon dioxide, glycerol, and other fermentation products, many of which contribute to beer’s overall flavour characteristics. This review will only focus on brewer’s yeast flocculation characteristics.

  4. Industrial brewing yeast engineered for the production of primary flavor determinants in hopped beer

    DEFF Research Database (Denmark)

    Denby, Charles M.; Li, Rachel A.; Vu, Van T.

    2018-01-01

    Flowers of the hop plant provide both bitterness and "hoppy" flavor to beer. Hops are, however, both a water and energy intensive crop and vary considerably in essential oil content, making it challenging to achieve a consistent hoppy taste in beer. Here, we report that brewer's yeast can...... be engineered to biosynthesize aromatic monoterpene molecules that impart hoppy flavor to beer by incorporating recombinant DNA derived from yeast, mint, and basil. Whereas metabolic engineering of biosynthetic pathways is commonly enlisted to maximize product titers, tuning expression of pathway enzymes...

  5. Yeast synthetic biology toolbox and applications for biofuel production.

    Science.gov (United States)

    Tsai, Ching-Sung; Kwak, Suryang; Turner, Timothy L; Jin, Yong-Su

    2015-02-01

    Yeasts are efficient biofuel producers with numerous advantages outcompeting bacterial counterparts. While most synthetic biology tools have been developed and customized for bacteria especially for Escherichia coli, yeast synthetic biological tools have been exploited for improving yeast to produce fuels and chemicals from renewable biomass. Here we review the current status of synthetic biological tools and their applications for biofuel production, focusing on the model strain Saccharomyces cerevisiae We describe assembly techniques that have been developed for constructing genes, pathways, and genomes in yeast. Moreover, we discuss synthetic parts for allowing precise control of gene expression at both transcriptional and translational levels. Applications of these synthetic biological approaches have led to identification of effective gene targets that are responsible for desirable traits, such as cellulosic sugar utilization, advanced biofuel production, and enhanced tolerance against toxic products for biofuel production from renewable biomass. Although an array of synthetic biology tools and devices are available, we observed some gaps existing in tool development to achieve industrial utilization. Looking forward, future tool development should focus on industrial cultivation conditions utilizing industrial strains. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permission@oup.com.

  6. Metabolic engineering of yeast for lignocellulosic biofuel production.

    Science.gov (United States)

    Jin, Yong-Su; Cate, Jamie Hd

    2017-12-01

    Production of biofuels from lignocellulosic biomass remains an unsolved challenge in industrial biotechnology. Efforts to use yeast for conversion face the question of which host organism to use, counterbalancing the ease of genetic manipulation with the promise of robust industrial phenotypes. Saccharomyces cerevisiae remains the premier host for metabolic engineering of biofuel pathways, due to its many genetic, systems and synthetic biology tools. Numerous engineering strategies for expanding substrate ranges and diversifying products of S. cerevisiae have been developed. Other yeasts generally lack these tools, yet harbor superior phenotypes that could be exploited in the harsh processes required for lignocellulosic biofuel production. These include thermotolerance, resistance to toxic compounds generated during plant biomass deconstruction, and wider carbon consumption capabilities. Although promising, these yeasts have yet to be widely exploited. By contrast, oleaginous yeasts such as Yarrowia lipolytica capable of producing high titers of lipids are rapidly advancing in terms of the tools available for their metabolic manipulation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Yeast as a Heterologous Model System to Uncover Type III Effector Function.

    Directory of Open Access Journals (Sweden)

    Crina Popa

    2016-02-01

    Full Text Available Type III effectors (T3E are key virulence proteins that are injected by bacterial pathogens inside the cells of their host to subvert cellular processes and contribute to disease. The budding yeast Saccharomyces cerevisiae represents an important heterologous system for the functional characterisation of T3E proteins in a eukaryotic environment. Importantly, yeast contains eukaryotic processes with low redundancy and are devoid of immunity mechanisms that counteract T3Es and mask their function. Expression in yeast of effectors from both plant and animal pathogens that perturb conserved cellular processes often resulted in robust phenotypes that were exploited to elucidate effector functions, biochemical properties, and host targets. The genetic tractability of yeast and its amenability for high-throughput functional studies contributed to the success of this system that, in recent years, has been used to study over 100 effectors. Here, we provide a critical view on this body of work and describe advantages and limitations inherent to the use of yeast in T3E research. "Favourite" targets of T3Es in yeast are cytoskeleton components and small GTPases of the Rho family. We describe how mitogen-activated protein kinase (MAPK signalling, vesicle trafficking, membrane structures, and programmed cell death are also often altered by T3Es in yeast and how this reflects their function in the natural host. We describe how effector structure-function studies and analysis of candidate targeted processes or pathways can be carried out in yeast. We critically analyse technologies that have been used in yeast to assign biochemical functions to T3Es, including transcriptomics and proteomics, as well as suppressor, gain-of-function, or synthetic lethality screens. We also describe how yeast can be used to select for molecules that block T3E function in search of new antibacterial drugs with medical applications. Finally, we provide our opinion on the limitations

  8. Yeast functional genomic screens lead to identification of a role for a bacterial effector in innate immunity regulation.

    Directory of Open Access Journals (Sweden)

    Roger W Kramer

    2007-02-01

    Full Text Available Numerous bacterial pathogens manipulate host cell processes to promote infection and ultimately cause disease through the action of proteins that they directly inject into host cells. Identification of the targets and molecular mechanisms of action used by these bacterial effector proteins is critical to understanding pathogenesis. We have developed a systems biological approach using the yeast Saccharomyces cerevisiae that can expedite the identification of cellular processes targeted by bacterial effector proteins. We systematically screened the viable yeast haploid deletion strain collection for mutants hypersensitive to expression of the Shigella type III effector OspF. Statistical data mining of the results identified several cellular processes, including cell wall biogenesis, which when impaired by a deletion caused yeast to be hypersensitive to OspF expression. Microarray experiments revealed that OspF expression resulted in reversed regulation of genes regulated by the yeast cell wall integrity pathway. The yeast cell wall integrity pathway is a highly conserved mitogen-activated protein kinase (MAPK signaling pathway, normally activated in response to cell wall perturbations. Together these results led us to hypothesize and subsequently demonstrate that OspF inhibited both yeast and mammalian MAPK signaling cascades. Furthermore, inhibition of MAPK signaling by OspF is associated with attenuation of the host innate immune response to Shigella infection in a mouse model. These studies demonstrate how yeast systems biology can facilitate functional characterization of pathogenic bacterial effector proteins.

  9. [Yeast species in vulvovaginitis candidosa].

    Science.gov (United States)

    Nemes-Nikodém, Éva; Tamási, Béla; Mihalik, Noémi; Ostorházi, Eszter

    2015-01-04

    Vulvovaginal candidiasis is the most common mycosis, however, the available information about antifungal susceptibilities of these yeasts is limited. To compare the gold standard fungal culture with a new molecular identification method and report the incidence of yeast species in vulvovaginitis candidosa. The authors studied 370 yeasts isolated from vulvovaginal candidiasis and identified them by phenotypic and molecular methods. The most common species was Candida albicans (85%), followed by Candida glabrata, and other Candida species. At present there are no recommendations for the evaluation of antifungal susceptibility of pathogenic fungal species occurring in vulvovaginal candidiasis and the natural antifungal resistance of the different species is known only. Matrix Assisted Laser Desorption Ionization Time of Flight identification can be used to differentiate the fluconazole resistant Candida dubliniensis and the sensitive Candida albicans strains.

  10. Reserve carbohydrates metabolism in the yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    François, J; Parrou, J L

    2001-01-01

    Glycogen and trehalose are the two glucose stores of yeast cells. The large variations in the cell content of these two compounds in response to different environmental changes indicate that their metabolism is controlled by complex regulatory systems. In this review we present information on the regulation of the activity of the enzymes implicated in the pathways of synthesis and degradation of glycogen and trehalose as well as on the transcriptional control of the genes encoding them. cAMP and the protein kinases Snf1 and Pho85 appear as major actors in this regulation. From a metabolic point of view, glucose-6-phosphate seems the major effector in the net synthesis of glycogen and trehalose. We discuss also the implication of the recently elucidated TOR-dependent nutrient signalling pathway in the control of the yeast glucose stores and its integration in growth and cell division. The unexpected roles of glycogen and trehalose found in the control of glycolytic flux, stress responses and energy stores for the budding process, demonstrate that their presence confers survival and reproductive advantages to the cell. The findings discussed provide for the first time a teleonomic value for the presence of two different glucose stores in the yeast cell.

  11. Visible light alters yeast metabolic rhythms by inhibiting respiration.

    Science.gov (United States)

    Robertson, James Brian; Davis, Chris R; Johnson, Carl Hirschie

    2013-12-24

    Exposure of cells to visible light in nature or in fluorescence microscopy often is considered to be relatively innocuous. However, using the yeast respiratory oscillation (YRO) as a sensitive measurement of metabolism, we find that non-UV visible light has a significant impact on yeast metabolism. Blue/green wavelengths of visible light shorten the period and dampen the amplitude of the YRO, which is an ultradian rhythm of cell metabolism and transcription. The wavelengths of light that have the greatest effect coincide with the peak absorption regions of cytochromes. Moreover, treating yeast with the electron transport inhibitor sodium azide has similar effects on the YRO as visible light. Because impairment of respiration by light would change several state variables believed to play vital roles in the YRO (e.g., oxygen tension and ATP levels), we tested oxygen's role in YRO stability and found that externally induced oxygen depletion can reset the phase of the oscillation, demonstrating that respiratory capacity plays a role in the oscillation's period and phase. Light-induced damage to the cytochromes also produces reactive oxygen species that up-regulate the oxidative stress response gene TRX2 that is involved in pathways that enable sustained growth in bright visible light. Therefore, visible light can modulate cellular rhythmicity and metabolism through unexpectedly photosensitive pathways.

  12. Dietary live yeast alters metabolic profiles, protein biosynthesis and thermal stress tolerance of Drosophila melanogaster.

    Science.gov (United States)

    Colinet, Hervé; Renault, David

    2014-04-01

    The impact of nutritional factors on insect's life-history traits such as reproduction and lifespan has been excessively examined; however, nutritional determinant of insect's thermal tolerance has not received a lot of attention. Dietary live yeast represents a prominent source of proteins and amino acids for laboratory-reared drosophilids. In this study, Drosophila melanogaster adults were fed on diets supplemented or not with live yeast. We hypothesized that manipulating nutritional conditions through live yeast supplementation would translate into altered physiology and stress tolerance. We verified how live yeast supplementation affected body mass characteristics, total lipids and proteins, metabolic profiles and cold tolerance (acute and chronic stress). Females fed with live yeast had increased body mass and contained more lipids and proteins. Using GC/MS profiling, we found distinct metabolic fingerprints according to nutritional conditions. Metabolite pathway enrichment analysis corroborated that live yeast supplementation was associated with amino acid and protein biosyntheses. The cold assays revealed that the presence of dietary live yeast greatly promoted cold tolerance. Hence, this study conclusively demonstrates a significant interaction between nutritional conditions and thermal tolerance. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Cell-surface display of enzymes by the yeast Saccharomyces cerevisiae for synthetic biology.

    Science.gov (United States)

    Tanaka, Tsutomu; Kondo, Akihiko

    2015-02-01

    In yeast cell-surface displays, functional proteins, such as cellulases, are genetically fused to an anchor protein and expressed on the cell surface. Saccharomyces cerevisiae, which is often utilized as a cell factory for the production of fuels, chemicals, and proteins, is the most commonly used yeast for cell-surface display. To construct yeast cells with a desired function, such as the ability to utilize cellulose as a substrate for bioethanol production, cell-surface display techniques for the efficient expression of enzymes on the cell membrane need to be combined with metabolic engineering approaches for manipulating target pathways within cells. In this Minireview, we summarize the recent progress of biorefinery fields in the development and application of yeast cell-surface displays from a synthetic biology perspective and discuss approaches for further enhancing cell-surface display efficiency. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permission@oup.com.

  14. Radiation stimulation of yeast crops for increasing output of alcohol and baker yeasts

    International Nuclear Information System (INIS)

    Vlad, E.; Marsheu, P.

    1974-01-01

    The purpose of this study was to stimulate by gamma radiation the existing commercial types of yeast so as to obtain yeasts that would better reflect the substrate and have improved reproductive capacity. The experiments were conducted under ordinary conditions using commercial yeasts received from one factory producing alcohol and bakery yeasts and isolated as pure cultures. Irradiating yeast cultures with small doses (up to 10 krad) was found to stimulate the reproduction and fermenting activity of yeast cells as manifested in increased accumulation of yeast biomass and greater yield of ethyl alcohol. (E.T.)

  15. Functional morphology of the secretory pathway organelles in yeast

    Czech Academy of Sciences Publication Activity Database

    Voříšek, Josef

    2000-01-01

    Roč. 51, - (2000), s. 530-546 ISSN 1059-910X Institutional research plan: CEZ:AV0Z5020903 Keywords : Saccharomyces cerevisiae * secretion * glycoproteins Subject RIV: EE - Microbiology, Virology Impact factor: 1.746, year: 2000

  16. Fission Yeast Model Study for Dissection of TSC Pathway

    Science.gov (United States)

    2010-04-01

    cerevisiae;Hs, Homo sapiens ;Dm,Drosophilamelanogaster. (C)Themulticopy suppressors ofDtsc2 cpp1-1cells.Dtsc2 cpp1-1cells carrying each of the five...distribution of their cell length was measured (right pan- els ). For each strain, .100 cells were counted. The experi- ments were performed three times with...dependent GAP activity. Taken together, we specu- late that rhb1-DA4 can stimulate its downstream ele - ments regardless of the guanine-nucleotide-binding

  17. Quantitative phosphoproteomics applied to the yeast pheromone signaling pathway

    DEFF Research Database (Denmark)

    Gruhler, Albrecht; Olsen, Jesper Velgaard; Mohammed, Shabaz

    2005-01-01

    of a detailed molecular view of complex biological processes. We present a quantitative modification-specific proteomic approach that combines stable isotope labeling by amino acids in cell culture (SILAC) for quantitation with IMAC for phosphopeptide enrichment and three stages of mass spectrometry (MS....... Phosphopeptide fractions were analyzed by LC-MS using a linear ion trap-Fourier transform ion cyclotron resonance mass spectrometer. MS/MS and neutral loss-directed MS/MS/MS analysis allowed detection and sequencing of phosphopeptides with exceptional accuracy and specificity. Of more than 700 identified...

  18. The Yeast Saccharomyces cerevisiae as a Model for Understanding RAS Proteins and Their Role in Human Tumorigenesis

    Science.gov (United States)

    Cazzanelli, Giulia; Francisco, Rita; Azevedo, Luísa; Carvalho, Patrícia Dias; Almeida, Ana; Côrte-Real, Manuela; Oliveira, Maria José; Lucas, Cândida; Sousa, Maria João

    2018-01-01

    The exploitation of the yeast Saccharomyces cerevisiae as a biological model for the investigation of complex molecular processes conserved in multicellular organisms, such as humans, has allowed fundamental biological discoveries. When comparing yeast and human proteins, it is clear that both amino acid sequences and protein functions are often very well conserved. One example of the high degree of conservation between human and yeast proteins is highlighted by the members of the RAS family. Indeed, the study of the signaling pathways regulated by RAS in yeast cells led to the discovery of properties that were often found interchangeable with RAS proto-oncogenes in human pathways, and vice versa. In this work, we performed an updated critical literature review on human and yeast RAS pathways, specifically highlighting the similarities and differences between them. Moreover, we emphasized the contribution of studying yeast RAS pathways for the understanding of human RAS and how this model organism can contribute to unveil the roles of RAS oncoproteins in the regulation of mechanisms important in the tumorigenic process, like autophagy. PMID:29463063

  19. Synthetic genome engineering forging new frontiers for wine yeast.

    Science.gov (United States)

    Pretorius, Isak S

    2017-02-01

    Over the past 15 years, the seismic shifts caused by the convergence of biomolecular, chemical, physical, mathematical, and computational sciences alongside cutting-edge developments in information technology and engineering have erupted into a new field of scientific endeavor dubbed Synthetic Biology. Recent rapid advances in high-throughput DNA sequencing and DNA synthesis techniques are enabling the design and construction of new biological parts (genes), devices (gene networks) and modules (biosynthetic pathways), and the redesign of biological systems (cells and organisms) for useful purposes. In 2014, the budding yeast Saccharomyces cerevisiae became the first eukaryotic cell to be equipped with a fully functional synthetic chromosome. This was achieved following the synthesis of the first viral (poliovirus in 2002 and bacteriophage Phi-X174 in 2003) and bacterial (Mycoplasma genitalium in 2008 and Mycoplasma mycoides in 2010) genomes, and less than two decades after revealing the full genome sequence of a laboratory (S288c in 1996) and wine (AWRI1631 in 2008) yeast strain. A large international project - the Synthetic Yeast Genome (Sc2.0) Project - is now underway to synthesize all 16 chromosomes (∼12 Mb carrying ∼6000 genes) of the sequenced S288c laboratory strain by 2018. If successful, S. cerevisiae will become the first eukaryote to cross the horizon of in silico design of complex cells through de novo synthesis, reshuffling, and editing of genomes. In the meantime, yeasts are being used as cell factories for the semi-synthetic production of high-value compounds, such as the potent antimalarial artemisinin, and food ingredients, such as resveratrol, vanillin, stevia, nootkatone, and saffron. As a continuum of previously genetically engineered industrially important yeast strains, precision genome engineering is bound to also impact the study and development of wine yeast strains supercharged with synthetic DNA. The first taste of what the future

  20. Synthetic yeast based cell factories for vanillin-glucoside production

    DEFF Research Database (Denmark)

    Strucko, Tomas

    and controlled expression/overexpression of genes of interest. De novo biosynthetic pathway for vanillin-β-glucoside production was employed as a model system for several case studies in this project. In order to construct yeast cell factories fulfilling current demands of industrial biotechnology, methods......The yeast Saccharomyces cerevisiae is well a characterized microorganism and widely used as eukaryotic model organism as well as a key cell factory for bioproduction of various products. The latter comprise a large variety of scientifically and industrially relevant products such as low-value bulk...... chemicals and biofuels, food additives, high-value chemicals and recombinant proteins. Despite the recent achievements in the fields of systems biology and metabolic engineering together with availability of broad genetic engineering toolbox, the full potential of S. cerevisiae as a cell factory is not yet...

  1. MPact: the MIPS protein interaction resource on yeast.

    Science.gov (United States)

    Güldener, Ulrich; Münsterkötter, Martin; Oesterheld, Matthias; Pagel, Philipp; Ruepp, Andreas; Mewes, Hans-Werner; Stümpflen, Volker

    2006-01-01

    In recent years, the Munich Information Center for Protein Sequences (MIPS) yeast protein-protein interaction (PPI) dataset has been used in numerous analyses of protein networks and has been called a gold standard because of its quality and comprehensiveness [H. Yu, N. M. Luscombe, H. X. Lu, X. Zhu, Y. Xia, J. D. Han, N. Bertin, S. Chung, M. Vidal and M. Gerstein (2004) Genome Res., 14, 1107-1118]. MPact and the yeast protein localization catalog provide information related to the proximity of proteins in yeast. Beside the integration of high-throughput data, information about experimental evidence for PPIs in the literature was compiled by experts adding up to 4300 distinct PPIs connecting 1500 proteins in yeast. As the interaction data is a complementary part of CYGD, interactive mapping of data on other integrated data types such as the functional classification catalog [A. Ruepp, A. Zollner, D. Maier, K. Albermann, J. Hani, M. Mokrejs, I. Tetko, U. Güldener, G. Mannhaupt, M. Münsterkötter and H. W. Mewes (2004) Nucleic Acids Res., 32, 5539-5545] is possible. A survey of signaling proteins and comparison with pathway data from KEGG demonstrates that based on these manually annotated data only an extensive overview of the complexity of this functional network can be obtained in yeast. The implementation of a web-based PPI-analysis tool allows analysis and visualization of protein interaction networks and facilitates integration of our curated data with high-throughput datasets. The complete dataset as well as user-defined sub-networks can be retrieved easily in the standardized PSI-MI format. The resource can be accessed through http://mips.gsf.de/genre/proj/mpact.

  2. Surplus yeast tank failing catastrophically

    DEFF Research Database (Denmark)

    Hedlund, Frank Huess

    2016-01-01

    GOOD REASON FOR CAUTION I A large surplus yeast tank shot into the air leaving the floor plate and the contents behind. Although not designed for overpressure, the tank was kept at “very slight overpressure” to suppress nuisance foaming. The brewery was unaware of the hazards of compressed air...

  3. Yeast genomics on food flavours

    NARCIS (Netherlands)

    Schoondermark-Stolk, Sung Ah

    2005-01-01

    The appearance and concentration of the fusel alcohol 3-methyl-1-butanol is important for the flavour of fermented foods. 3-Methyl-1-butanol is formed by yeast during the conversion of L-leucine. Identification of the enzymes and genes involved in the formation of 3-methyl-1-butanol is a major

  4. Mechanisms of uv mutagenesis in yeast

    International Nuclear Information System (INIS)

    Lawrence, C.W.; Christensen, R.; Schwartz, A.

    1982-01-01

    The uv mutagenesis in yeast depends on the function of the RAD6 locus, a gene that is also responsible for a substantial fraction of wild-type resistance, suggesting that this eukaryote may possess a misrepair mechanism analogous to that proposed for Escherichia coli. The molecular mechanism responsible for RAD6 repair or recovery is not yet known, but it is different from either excision or recombination-dependent repair, processes carried out by the other two main repair pathways in yeast. RAD6-dependent mutagenesis has been found to have the following characteristics. It is associated at best with only a small fraction of RAD6-dependent repair, the majority of the sensitivity of rad6 mutants being due to their lack of nonmutagenic repair. SRS2 metabolic suppressors restore a substantial fraction of uv resistance to rad6 mutants but do not restore their uv mutability. Strains containing mutations at loci (rev, umr) that are probably more directly involved in mutagenesis are only mildly sensitive, and there is a poor correlation between their sensitivity and mutational deficiency. The uv mutagenesis appears to require a large number of gene functions, perhaps ten or more. Where examined in detail, these genes have been found to be concerned in the production of only a specific range of mutational events, not all of them. Mating experiments have shown that a substantial fraction, probably 40% or more, of uv-induced mutations are untargeted, that is, occur in lesion-free regions of DNA. The uv irradiation, therefore, produces a general reduction in the normally high fidelity with which DNA is replicated on undamaged templates. It does not appear to be necessary for the causal lesion to be present in the same chromosome as the mutation it induces. The reduction in fidelity may be the consequence of the production of a diffusible factor in uv-irradiated cells, but definite evidence supporting this proposal has not yet been obtained

  5. The unfolded protein response has a protective role in yeast models of classic galactosemia

    Directory of Open Access Journals (Sweden)

    Evandro A. De-Souza

    2014-01-01

    Full Text Available Classic galactosemia is a human autosomal recessive disorder caused by mutations in the GALT gene (GAL7 in yeast, which encodes the enzyme galactose-1-phosphate uridyltransferase. Here we show that the unfolded protein response pathway is triggered by galactose in two yeast models of galactosemia: lithium-treated cells and the gal7Δ mutant. The synthesis of galactose-1-phosphate is essential to trigger the unfolded protein response under these conditions because the deletion of the galactokinase-encoding gene GAL1 completely abolishes unfolded protein response activation and galactose toxicity. Impairment of the unfolded protein response in both yeast models makes cells even more sensitive to galactose, unmasking its cytotoxic effect. These results indicate that endoplasmic reticulum stress is induced under galactosemic conditions and underscores the importance of the unfolded protein response pathway to cellular adaptation in these models of classic galactosemia.

  6. Endoplasmic reticulum involvement in yeast cell death

    International Nuclear Information System (INIS)

    Nicanor Austriaco, O.

    2012-01-01

    Yeast cells undergo programed cell death (PCD) with characteristic markers associated with apoptosis in mammalian cells including chromatin breakage, nuclear fragmentation, reactive oxygen species generation, and metacaspase activation. Though significant research has focused on mitochondrial involvement in this phenomenon, more recent work with both Saccharomyces cerevisiae and Schizosaccharomyces pombe has also implicated the endoplasmic reticulum (ER) in yeast PCD. This minireview provides an overview of ER stress-associated cell death (ER-SAD) in yeast. It begins with a description of ER structure and function in yeast before moving to a discussion of ER-SAD in both mammalian and yeast cells. Three examples of yeast cell death associated with the ER will be highlighted here including inositol starvation, lipid toxicity, and the inhibition of N-glycosylation. It closes by suggesting ways to further examine the involvement of the ER in yeast cell death.

  7. Brewing characteristics of piezosensitive sake yeasts

    Science.gov (United States)

    Nomura, Kazuki; Hoshino, Hirofumi; Igoshi, Kazuaki; Onozuka, Haruka; Tanaka, Erika; Hayashi, Mayumi; Yamazaki, Harutake; Takaku, Hiroaki; Iguchi, Akinori; Shigematsu, Toru

    2018-04-01

    Application of high hydrostatic pressure (HHP) treatment to food processing is expected as a non-thermal fermentation regulation technology that supresses over fermentation. However, the yeast Saccharomyces cerevisiae used for Japanese rice wine (sake) brewing shows high tolerance to HHP. Therefore, we aimed to generate pressure-sensitive (piezosensitive) sake yeast strains by mating sake with piezosensitive yeast strains to establish an HHP fermentation regulation technology and extend the shelf life of fermented foods. The results of phenotypic analyses showed that the generated yeast strains were piezosensitive and exhibited similar fermentation ability compared with the original sake yeast strain. In addition, primary properties of sake brewed using these strains, such as ethanol concentration, sake meter value and sake flavor compounds, were almost equivalent to those obtained using the sake yeast strain. These results suggest that the piezosensitive strains exhibit brewing characteristics essentially equivalent to those of the sake yeast strain.

  8. Protein and Amino Acid Restriction, Aging and Disease: from yeast to humans

    OpenAIRE

    Mirzaei, Hamed; Suarez, Jorge A.; Longo, Valter D.

    2014-01-01

    Many of the effects of dietary restriction (DR) on longevity and health span in model organisms have been linked to reduced protein and amino acid (AA) intake and the stimulation of specific nutrient signaling pathways. Studies in yeast have shown that addition of serine, threonine, and valine in media promotes cellular sensitization and aging by activating different but connected pathways. Protein or essential AA restriction extends both lifespan and healthspan in rodent models. In humans, p...

  9. Directed evolution of xylose isomerase for improved xylose catabolism and fermentation in the yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    Lee, Sun-Mi; Jellison, Taylor; Alper, Hal S

    2012-08-01

    The heterologous expression of a highly functional xylose isomerase pathway in Saccharomyces cerevisiae would have significant advantages for ethanol yield, since the pathway bypasses cofactor requirements found in the traditionally used oxidoreductase pathways. However, nearly all reported xylose isomerase-based pathways in S. cerevisiae suffer from poor ethanol productivity, low xylose consumption rates, and poor cell growth compared with an oxidoreductase pathway and, additionally, often require adaptive strain evolution. Here, we report on the directed evolution of the Piromyces sp. xylose isomerase (encoded by xylA) for use in yeast. After three rounds of mutagenesis and growth-based screening, we isolated a variant containing six mutations (E15D, E114G, E129D, T142S, A177T, and V433I) that exhibited a 77% increase in enzymatic activity. When expressed in a minimally engineered yeast host containing a gre3 knockout and tal1 and XKS1 overexpression, the strain expressing this mutant enzyme improved its aerobic growth rate by 61-fold and both ethanol production and xylose consumption rates by nearly 8-fold. Moreover, the mutant enzyme enabled ethanol production by these yeasts under oxygen-limited fermentation conditions, unlike the wild-type enzyme. Under microaerobic conditions, the ethanol production rates of the strain expressing the mutant xylose isomerase were considerably higher than previously reported values for yeast harboring a xylose isomerase pathway and were also comparable to those of the strains harboring an oxidoreductase pathway. Consequently, this study shows the potential to evolve a xylose isomerase pathway for more efficient xylose utilization.

  10. Soya bean Gα proteins with distinct biochemical properties exhibit differential ability to complement Saccharomyces cerevisiae gpa1 mutant.

    Science.gov (United States)

    Roy Choudhury, Swarup; Wang, Yuqi; Pandey, Sona

    2014-07-01

    Signalling pathways mediated by heterotrimeric G-proteins are common to all eukaryotes. Plants have a limited number of each of the G-protein subunits, with the most elaborate G-protein network discovered so far in soya bean (Glycine max, also known as soybean) which has four Gα, four Gβ and ten Gγ proteins. Biochemical characterization of Gα proteins from plants suggests significant variation in their properties compared with the well-characterized non-plant proteins. Furthermore, the four soya bean Gα (GmGα) proteins exhibit distinct biochemical activities among themselves, but the extent to which such biochemical differences contribute to their in vivo function is also not known. We used the yeast gpa1 mutant which displays constitutive signalling and growth arrest in the pheromone-response pathway as an in vivo model to evaluate the effect of distinct biochemical activities of GmGα proteins. We showed that specific GmGα proteins can be activated during pheromone-dependent receptor-mediated signalling in yeast and they display different strengths towards complementation of yeast gpa1 phenotypes. We also identified amino acids that are responsible for differential complementation abilities of specific Gα proteins. These data establish that specific plant Gα proteins are functional in the receptor-mediated pheromone-response pathway in yeast and that the subtle biochemical differences in their activity are physiologically relevant.

  11. Yeast Isolation for Bioethanol Production

    Directory of Open Access Journals (Sweden)

    EKA RURIANI

    2012-09-01

    Full Text Available We have isolated 12 yeast isolates from five different rotten fruits by using a yeast glucose chloramphenicol agar (YGCA medium supplemented with tetracycline. From pre-screening assay, four isolates exhibited higher substrate (glucose-xylose consumption efficiency in the reaction tube fermentation compared to Saccharomyces cerevisiae dan Saccharomyces ellipsoids as the reference strains. Based on the fermentation process in gooseneck flasks, we observed that two isolates (K and SB showed high fermentation efficiency both in sole glucose and mixed glucose-xylose substrate. Moreover, isolates K and SB produced relatively identical level of ethanol concentration compared to the reference strains. Isolates H and MP could only produce high levels of ethanol in glucose fermentation, while only half of that amount of ethanol was detected in glucose-xylose fermentation. Isolate K and SB were identified as Pichia kudriavzeevii (100% based on large sub unit (LSU ribosomal DNA D1/D2 region.

  12. Genetic and physiological factors affecting repair and mutagenesis in yeast

    Energy Technology Data Exchange (ETDEWEB)

    Lemontt, J F

    1979-01-01

    Current views of DNA repair and mutagenesis in the yeast Saccharomyces cerevisiae are discussed in the light of recent data, and with emphasis on the isolation and characterization of genetically well-defined mutations that affect DNA metabolism in general (including replication and recombination). Various pathways of repair are described particularly in relation to their involvement in mutagenic mechanisms. In addition to genetic control, certain physiological factors such as cell age, DNA replication, and the regulatory state of the mating-type locus, are shown to also play a role in repair and mutagenesis.

  13. Genetic and physiological factors affecting repair and mutagenesis in yeast

    Energy Technology Data Exchange (ETDEWEB)

    Lemontt, J F

    1979-01-01

    Current views of DNA repair and mutagenesis in the yeast Saccharomyces cerevisiae are discussed in the light of recent data and with emphasis on the isolation and characterization of genetically well-defined mutations that affect DNA metabolism in general (including replication and recombination). Various pathways of repair are described, particularly in relation to their imvolvement in mutagenic mechanisms. In addition to genetic control, certain physiological factors such as cell age, DNA replication, and the regulatory state of the mating-type locus are shown to also play a role in repair and mutagenesis.

  14. Genetic and physiological factors affecting repair and mutagenesis in yeast

    International Nuclear Information System (INIS)

    Lemontt, J.F.

    1979-01-01

    Current views of DNA repair and mutagenesis in the yeast Saccharomyces cerevisiae are discussed in the light of recent data, and with emphasis on the isolation and characterization of genetically well-defined mutations that affect DNA metabolism in general (including replication and recombination). Various pathways of repair are described particularly in relation to their involvement in mutagenic mechanisms. In addition to genetic control, certain physiological factors such as cell age, DNA replication, and the regulatory state of the mating-type locus, are shown to also play a role in repair and mutagenesis

  15. Genetic and physiological factors affecting repair and mutagenesis in yeast

    International Nuclear Information System (INIS)

    Lemontt, J.F.

    1979-01-01

    Current views of DNA repair and mutagenesis in the yeast Saccharomyces cerevisiae are discussed in the light of recent data and with emphasis on the isolation and characterization of genetically well-defined mutations that affect DNA metabolism in general (including replication and recombination). Various pathways of repair are described, particularly in relation to their imvolvement in mutagenic mechanisms. In addition to genetic control, certain physiological factors such as cell age, DNA replication, and the regulatory state of the mating-type locus are shown to also play a role in repair and mutagenesis

  16. Regulation of glycoprotein synthesis in yeast by mating pheromones

    International Nuclear Information System (INIS)

    Tanner, W.

    1984-01-01

    In Saccharomyces cerevisiae, glycosylated proteins amount to less than 2% of the cell protein. Two intensively studied examples of yeast glycoproteins are the external cell wall - associated invertase and the vacuolar carboxypeptidase Y. Recently, it was shown that the mating pheromone, alpha factor, specifically and strongly inhibits the synthesis of N-glycosylated proteins in haploid a cells, whereas O-glycosylated proteins are not affected. In this paper, the pathways of glycoprotein biosynthesis are summarized briefly, and evidence is presented that mating pheomones have a regulatory function in glycoprotein synthesis

  17. Oral yeast colonization throughout pregnancy

    OpenAIRE

    Rio, Rute; Sim?es-Silva, Liliana; Garro, Sofia; Silva, M?rio-Jorge; Azevedo, ?lvaro; Sampaio-Maia, Benedita

    2017-01-01

    Background Recent studies suggest that placenta may harbour a unique microbiome that may have origin in maternal oral microbiome. Although the major physiological and hormonal adjustments observed in pregnant women lead to biochemical and microbiological modifications of the oral environment, very few studies evaluated the changes suffered by the oral microbiota throughout pregnancy. So, the aim of our study was to evaluate oral yeast colonization throughout pregnancy and to compare it with n...

  18. Studies of the expression of human poly(ADP-ribose) polymerase-1 in Saccharomyces cerevisiae and identification of PARP-1 substrates by yeast proteome microarray screening.

    Science.gov (United States)

    Tao, Zhihua; Gao, Peng; Liu, Hung-Wen

    2009-12-15

    Poly(ADP-ribosyl)ation of various nuclear proteins catalyzed by a family of NAD(+)-dependent enzymes, poly(ADP-ribose) polymerases (PARPs), is an important posttranslational modification reaction. PARP activity has been demonstrated in all types of eukaryotic cells with the exception of yeast, in which the expression of human PARP-1 was shown to lead to retarded cell growth. We investigated the yeast growth inhibition caused by human PARP-1 expression in Saccharomyces cerevisiae. Flow cytometry analysis reveals that PARP-1-expressing yeast cells accumulate in the G(2)/M stage of the cell cycle. Confocal microscopy analysis shows that human PARP-1 is distributed throughout the nucleus of yeast cells but is enriched in the nucleolus. Utilizing yeast proteome microarray screening, we identified 33 putative PARP-1 substrates, six of which are known to be involved in ribosome biogenesis. The poly(ADP-ribosyl)ation of three of these yeast proteins, together with two human homologues, was confirmed by an in vitro PARP-1 assay. Finally, a polysome profile analysis using sucrose gradient ultracentrifugation demonstrated that the ribosome levels in yeast cells expressing PARP-1 are lower than those in control yeast cells. Overall, our data suggest that human PARP-1 may affect ribosome biogenesis by modifying certain nucleolar proteins in yeast. The artificial PARP-1 pathway in yeast may be used as a simple platform to identify substrates and verify function of this important enzyme.

  19. Residual mitochondrial transmembrane potential decreases unsaturated fatty acid level in sake yeast during alcoholic fermentation

    Directory of Open Access Journals (Sweden)

    Kazutaka Sawada

    2016-01-01

    Full Text Available Oxygen, a key nutrient in alcoholic fermentation, is rapidly depleted during this process. Several pathways of oxygen utilization have been reported in the yeast Saccharomyces cerevisiae during alcoholic fermentation, namely synthesis of unsaturated fatty acid, sterols and heme, and the mitochondrial electron transport chain. However, the interaction between these pathways has not been investigated. In this study, we showed that the major proportion of unsaturated fatty acids of ester-linked lipids in sake fermentation mash is derived from the sake yeast rather than from rice or koji (rice fermented with Aspergillus. Additionally, during alcoholic fermentation, inhibition of the residual mitochondrial activity of sake yeast increases the levels of unsaturated fatty acids of ester-linked lipids. These findings indicate that the residual activity of the mitochondrial electron transport chain reduces molecular oxygen levels and decreases the synthesis of unsaturated fatty acids, thereby increasing the synthesis of estery flavors by sake yeast. This is the first report of a novel link between residual mitochondrial transmembrane potential and the synthesis of unsaturated fatty acids by the brewery yeast during alcoholic fermentation.

  20. Genome and metabolic engineering in non-conventional yeasts: Current advances and applications

    Directory of Open Access Journals (Sweden)

    Ann-Kathrin Löbs

    2017-09-01

    Full Text Available Microbial production of chemicals and proteins from biomass-derived and waste sugar streams is a rapidly growing area of research and development. While the model yeast Saccharomyces cerevisiae is an excellent host for the conversion of glucose to ethanol, production of other chemicals from alternative substrates often requires extensive strain engineering. To avoid complex and intensive engineering of S. cerevisiae, other yeasts are often selected as hosts for bioprocessing based on their natural capacity to produce a desired product: for example, the efficient production and secretion of proteins, lipids, and primary metabolites that have value as commodity chemicals. Even when using yeasts with beneficial native phenotypes, metabolic engineering to increase yield, titer, and production rate is essential. The non-conventional yeasts Kluyveromyces lactis, K. marxianus, Scheffersomyces stipitis, Yarrowia lipolytica, Hansenula polymorpha and Pichia pastoris have been developed as eukaryotic hosts because of their desirable phenotypes, including thermotolerance, assimilation of diverse carbon sources, and high protein secretion. However, advanced metabolic engineering in these yeasts has been limited. This review outlines the challenges of using non-conventional yeasts for strain and pathway engineering, and discusses the developed solutions to these problems and the resulting applications in industrial biotechnology.

  1. Genome and metabolic engineering in non-conventional yeasts: Current advances and applications.

    Science.gov (United States)

    Löbs, Ann-Kathrin; Schwartz, Cory; Wheeldon, Ian

    2017-09-01

    Microbial production of chemicals and proteins from biomass-derived and waste sugar streams is a rapidly growing area of research and development. While the model yeast Saccharomyces cerevisia e is an excellent host for the conversion of glucose to ethanol, production of other chemicals from alternative substrates often requires extensive strain engineering. To avoid complex and intensive engineering of S. cerevisiae, other yeasts are often selected as hosts for bioprocessing based on their natural capacity to produce a desired product: for example, the efficient production and secretion of proteins, lipids, and primary metabolites that have value as commodity chemicals. Even when using yeasts with beneficial native phenotypes, metabolic engineering to increase yield, titer, and production rate is essential. The non-conventional yeasts Kluyveromyces lactis, K. marxianus, Scheffersomyces stipitis, Yarrowia lipolytica, Hansenula polymorpha and Pichia pastoris have been developed as eukaryotic hosts because of their desirable phenotypes, including thermotolerance, assimilation of diverse carbon sources, and high protein secretion. However, advanced metabolic engineering in these yeasts has been limited. This review outlines the challenges of using non-conventional yeasts for strain and pathway engineering, and discusses the developed solutions to these problems and the resulting applications in industrial biotechnology.

  2. Mutant power: using mutant allele collections for yeast functional genomics.

    Science.gov (United States)

    Norman, Kaitlyn L; Kumar, Anuj

    2016-03-01

    The budding yeast has long served as a model eukaryote for the functional genomic analysis of highly conserved signaling pathways, cellular processes and mechanisms underlying human disease. The collection of reagents available for genomics in yeast is extensive, encompassing a growing diversity of mutant collections beyond gene deletion sets in the standard wild-type S288C genetic background. We review here three main types of mutant allele collections: transposon mutagen collections, essential gene collections and overexpression libraries. Each collection provides unique and identifiable alleles that can be utilized in genome-wide, high-throughput studies. These genomic reagents are particularly informative in identifying synthetic phenotypes and functions associated with essential genes, including those modeled most effectively in complex genetic backgrounds. Several examples of genomic studies in filamentous/pseudohyphal backgrounds are provided here to illustrate this point. Additionally, the limitations of each approach are examined. Collectively, these mutant allele collections in Saccharomyces cerevisiae and the related pathogenic yeast Candida albicans promise insights toward an advanced understanding of eukaryotic molecular and cellular biology. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  3. Polyglutamine toxicity in yeast induces metabolic alterations and mitochondrial defects

    KAUST Repository

    Papsdorf, Katharina

    2015-09-03

    Background Protein aggregation and its pathological effects are the major cause of several neurodegenerative diseases. In Huntington’s disease an elongated stretch of polyglutamines within the protein Huntingtin leads to increased aggregation propensity. This induces cellular defects, culminating in neuronal loss, but the connection between aggregation and toxicity remains to be established. Results To uncover cellular pathways relevant for intoxication we used genome-wide analyses in a yeast model system and identify fourteen genes that, if deleted, result in higher polyglutamine toxicity. Several of these genes, like UGO1, ATP15 and NFU1 encode mitochondrial proteins, implying that a challenged mitochondrial system may become dysfunctional during polyglutamine intoxication. We further employed microarrays to decipher the transcriptional response upon polyglutamine intoxication, which exposes an upregulation of genes involved in sulfur and iron metabolism and mitochondrial Fe-S cluster formation. Indeed, we find that in vivo iron concentrations are misbalanced and observe a reduction in the activity of the prominent Fe-S cluster containing protein aconitase. Like in other yeast strains with impaired mitochondria, non-fermentative growth is impossible after intoxication with the polyglutamine protein. NMR-based metabolic analyses reveal that mitochondrial metabolism is reduced, leading to accumulation of metabolic intermediates in polyglutamine-intoxicated cells. Conclusion These data show that damages to the mitochondrial system occur in polyglutamine intoxicated yeast cells and suggest an intricate connection between polyglutamine-induced toxicity, mitochondrial functionality and iron homeostasis in this model system.

  4. A review on sustainable yeast biotechnological processes and applications

    DEFF Research Database (Denmark)

    Nandy, Subir Kumar; Srivastava, R. K.

    2018-01-01

    Yeast is very well known eukaryotic organism for its remarkable biodiversity and extensive industrial applications. Saccharomyces cerevisiae is one of the most widely used microorganisms in biotechnology with successful applications in the biochemical production. Biological conversion with the fo......Yeast is very well known eukaryotic organism for its remarkable biodiversity and extensive industrial applications. Saccharomyces cerevisiae is one of the most widely used microorganisms in biotechnology with successful applications in the biochemical production. Biological conversion...... with the focus on the different utilization of renewable feedstocks into fuels and chemicals has been intensively investigated due to increasing concerns on sustainability issues worldwide. Compared with its counterparts, Saccharomyces cerevisiae, the baker's yeast, is more industrially relevant due to known...... genetic and physiological background, the availability of a large collection of genetic tools, the compatibility of high-density and large-scale fermentation, and optimize the pathway for variety of products. Therefore, S. cerevisiae is one of the most popular cell factories and has been successfully used...

  5. Yeast metabolic engineering--targeting sterol metabolism and terpenoid formation.

    Science.gov (United States)

    Wriessnegger, Tamara; Pichler, Harald

    2013-07-01

    Terpenoids comprise various structures conferring versatile functions to eukaryotes, for example in the form of prenyl-anchors they attach proteins to membranes. The physiology of eukaryotic membranes is fine-tuned by another terpenoid class, namely sterols. Evidence is accumulating that numerous membrane proteins require specific sterol structural features for function. Moreover, sterols are intermediates in the synthesis of steroids serving as hormones in higher eukaryotes. Like steroids many compounds of the terpenoid family do not contribute to membrane architecture, but serve as signalling, protective or attractant/repellent molecules. Particularly plants have developed a plenitude of terpenoid biosynthetic routes branching off early in the sterol biosynthesis pathway and, thereby, forming one of the largest groups of naturally occurring organic compounds. Many of these aromatic and volatile molecules are interesting for industrial application ranging from foods to pharmaceuticals. Combining the fortunate situation that sterol biosynthesis is highly conserved in eukaryotes with the amenability of yeasts to genetic and metabolic engineering, basically all naturally occurring terpenoids might be produced involving yeasts. Such engineered yeasts are useful for the study of biological functions and molecular interactions of terpenoids as well as for the large-scale production of high-value compounds, which are unavailable in sufficient amounts from natural sources due to their low abundance. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Yeast flocculation: New story in fuel ethanol production.

    Science.gov (United States)

    Zhao, X Q; Bai, F W

    2009-01-01

    Yeast flocculation has been used in the brewing industry to facilitate biomass recovery for a long time, and thus its mechanism of yeast flocculation has been intensively studied. However, the application of flocculating yeast in ethanol production garnered attention mainly in the 1980s and 1990s. In this article, updated research progress in the molecular mechanism of yeast flocculation and the impact of environmental conditions on yeast flocculation are reviewed. Construction of flocculating yeast strains by genetic approach and utilization of yeast flocculation for ethanol production from various feedstocks were presented. The concept of self-immobilized yeast cells through their flocculation is revisited through a case study of continuous ethanol fermentation with the flocculating yeast SPSC01, and their technical and economic advantages are highlighted by comparing with yeast cells immobilized with supporting materials and regular free yeast cells as well. Taking the flocculating yeast SPSC01 as an example, the ethanol tolerance of the flocculating yeast was also discussed.

  7. Identification of Pathways Required for the Coordination of Late Mitotic Events in Animal Cells

    National Research Council Canada - National Science Library

    Baumgartner, Bridget L; Harper, J. W

    2005-01-01

    ... in genomic instability, a hallmark of cancer. In yeast, a signaling pathway has been identified, called the Mitotic Exit Network, which coordinates mitotic exit and cytokinesis with the end of anaphase...

  8. Identification of Pathways Required for the Coordination of Late Mitotic Events in Animal Cells

    National Research Council Canada - National Science Library

    Baumgartner, Bridget

    2004-01-01

    ... in genomic instability, a hallmark of cancer. In yeast, a signaling pathway has been identified, called the Mitotic Exit Network, which coordinates mitotic exit and cytokinesis with the end of anaphase...

  9. Yeasts Diversity in Fermented Foods and Beverages

    Science.gov (United States)

    Tamang, Jyoti Prakash; Fleet, Graham H.

    People across the world have learnt to culture and use the essential microorganisms for production of fermented foods and alcoholic beverages. A fermented food is produced either spontaneously or by adding mixed/pure starter culture(s). Yeasts are among the essential functional microorganisms encountered in many fermented foods, and are commercially used in production of baker's yeast, breads, wine, beer, cheese, etc. In Asia, moulds are predominant followed by amylolytic and alcohol-producing yeasts in the fermentation processes, whereas in Africa, Europe, Australia and America, fermented products are prepared exclusively using bacteria or bacteria-yeasts mixed cultures. This chapter would focus on the varieties of fermented foods and alcoholic beverages produced by yeasts, their microbiology and role in food fermentation, widely used commercial starters (pilot production, molecular aspects), production technology of some common commercial fermented foods and alcoholic beverages, toxicity and food safety using yeasts cultures and socio-economy

  10. Genetic basis of metabolome variation in yeast.

    Directory of Open Access Journals (Sweden)

    Jeffrey S Breunig

    2014-03-01

    Full Text Available Metabolism, the conversion of nutrients into usable energy and biochemical building blocks, is an essential feature of all cells. The genetic factors responsible for inter-individual metabolic variability remain poorly understood. To investigate genetic causes of metabolome variation, we measured the concentrations of 74 metabolites across ~ 100 segregants from a Saccharomyces cerevisiae cross by liquid chromatography-tandem mass spectrometry. We found 52 quantitative trait loci for 34 metabolites. These included linkages due to overt changes in metabolic genes, e.g., linking pyrimidine intermediates to the deletion of ura3. They also included linkages not directly related to metabolic enzymes, such as those for five central carbon metabolites to ira2, a Ras/PKA pathway regulator, and for the metabolites, S-adenosyl-methionine and S-adenosyl-homocysteine to slt2, a MAP kinase involved in cell wall integrity. The variant of ira2 that elevates metabolite levels also increases glucose uptake and ethanol secretion. These results highlight specific examples of genetic variability, including in genes without prior known metabolic regulatory function, that impact yeast metabolism.

  11. Drosophila Regulate Yeast Density and Increase Yeast Community Similarity in a Natural Substrate

    OpenAIRE

    Stamps, Judy A.; Yang, Louie H.; Morales, Vanessa M.; Boundy-Mills, Kyria L.

    2012-01-01

    Drosophila melanogaster adults and larvae, but especially larvae, had profound effects on the densities and community structure of yeasts that developed in banana fruits. Pieces of fruit exposed to adult female flies previously fed fly-conditioned bananas developed higher yeast densities than pieces of the same fruits that were not exposed to flies, supporting previous suggestions that adult Drosophila vector yeasts to new substrates. However, larvae alone had dramatic effects on yeast densit...

  12. Understanding start-up problems in yeast glycolysis.

    Science.gov (United States)

    Overal, Gosse B; Teusink, Bas; Bruggeman, Frank J; Hulshof, Josephus; Planqué, Robert

    2018-05-01

    Yeast glycolysis has been the focus of research for decades, yet a number of dynamical aspects of yeast glycolysis remain poorly understood at present. If nutrients are scarce, yeast will provide its catabolic and energetic needs with other pathways, but the enzymes catalysing upper glycolytic fluxes are still expressed. We conjecture that this overexpression facilitates the rapid transition to glycolysis in case of a sudden increase in nutrient concentration. However, if starved yeast is presented with abundant glucose, it can enter into an imbalanced state where glycolytic intermediates keep accumulating, leading to arrested growth and cell death. The bistability between regularly functioning and imbalanced phenotypes has been shown to depend on redox balance. We shed new light on these phenomena with a mathematical analysis of an ordinary differential equation model, including NADH to account for the redox balance. In order to gain qualitative insight, most of the analysis is parameter-free, i.e., without assigning a numerical value to any of the parameters. The model has a subtle bifurcation at the switch between an inviable equilibrium state and stable flux through glycolysis. This switch occurs if the ratio between the flux through upper glycolysis and ATP consumption rate of the cell exceeds a fixed threshold. If the enzymes of upper glycolysis would be barely expressed, our model predicts that there will be no glycolytic flux, even if external glucose would be at growth-permissable levels. The existence of the imbalanced state can be found for certain parameter conditions independent of the mentioned bifurcation. The parameter-free analysis proved too complex to directly gain insight into the imbalanced states, but the starting point of a branch of imbalanced states can be shown to exist in detail. Moreover, the analysis offers the key ingredients necessary for successful numerical continuation, which highlight the existence of this bistability and the

  13. The Yeast Retrograde Response as a Model of Intracellular Signaling of Mitochondrial Dysfunction

    Directory of Open Access Journals (Sweden)

    S. Michal eJazwinski

    2012-05-01

    Full Text Available Mitochondrial dysfunction activates intracellular signaling pathways that impact yeast longevity, and the best known of these pathways is the retrograde response. More recently, similar responses have been discerned in other systems, from invertebrates to human cells. However, the identity of the signal transducers is either unknown or apparently diverse, contrasting with the well-established signaling module of the yeast retrograde response. On the other hand, it has become equally clear that several other pathways and processes interact with the retrograde response, embedding it in a network responsive to a variety of cellular states. An examination of this network supports the notion that the master regulator NFkB aggregated a variety of mitochondria-related cellular responses at some point in evolution and has become the retrograde transcription factor. This has significant consequences for how we view some of the deficits associated with aging, such as inflammation. The support for NFkB as the retrograde response transcription factor is not only based on functional analyses. It is bolstered by the fact that NFkB can regulate Myc-Max, which is activated in human cells with dysfunctional mitochondria and impacts cellular metabolism. Myc-Max is homologous to the yeast retrograde response transcription factor Rtg1-Rtg3. Further research will be needed to disentangle the pro-aging from the anti-aging effects of NFkB. Interestingly, this is also a challenge for the complete understanding of the yeast retrograde response.

  14. Development of industrial yeast for second generation bioethanol production

    Energy Technology Data Exchange (ETDEWEB)

    Hou, X

    2012-01-15

    The cost of lignocellulose-based bioethanol needs to be reduced, in order to commercialize this clean and sustainable fuel substitute for fossil fuels. A microorganism that can completely and efficiently convert all the sugars in lignocellulose into ethanol is one of the prerequisites of a cost-effective production process. In addition, the microorganisms should also have a high tolerance towards the inhibitory compounds present in the lignocellulosic hydrolysate, which are formed during the pretreatment of lignocellulose. Baker's yeast, Saccharomyces cerevisiae, is generally regarded as a robust microorganism and can efficiently ferment glucose. But it lacks the ability to ferment xylose which comprises 20-35% of lignocellulose. Naturally xylose-fermenting yeast such as Pichia stipitis is much more sensitive to inhibitors than S. cerevisiae and it requires accurately controlled microaerophilic conditions during the xylose fermentation, rendering the process technically difficult and expensive. In this study, a novel xylose fermenting yeast Spathaspora passalidarum displayed fast cell growth and efficient xylose fermentation under anaerobic conditions. In contrast, P. stipitis was almost unable to utilize xylose under the same conditions. It is further demonstrated that S. passalidarum converts xylose by means of NADH-preferred xylose reductase (XR) and NAD+-dependent xylitol dehydrogenase (XDH). Thus, the capacity of S. passalidarum to utilize xylose under anaerobic conditions is possibly due to a balance between supply and demand of cofactor through this XR-XDH pathway. Only one other XR with NADH preference has been reported so far. Unfortunately, S. passalidarum also has a low tolerance towards inhibitors generated during pretreatment, which prevents immediate use of this yeast in industrial application. S. passalidarum is able to convert the inhibitor furfural to furfuryl alcohol in a synthetic medium when the addition of furfural is low. The enzymes involved

  15. Development of industrial yeast for second generation bioethanol production

    Energy Technology Data Exchange (ETDEWEB)

    Hou, X.

    2012-01-15

    The cost of lignocellulose-based bioethanol needs to be reduced, in order to commercialize this clean and sustainable fuel substitute for fossil fuels. A microorganism that can completely and efficiently convert all the sugars in lignocellulose into ethanol is one of the prerequisites of a cost-effective production process. In addition, the microorganisms should also have a high tolerance towards the inhibitory compounds present in the lignocellulosic hydrolysate, which are formed during the pretreatment of lignocellulose. Baker's yeast, Saccharomyces cerevisiae, is generally regarded as a robust microorganism and can efficiently ferment glucose. But it lacks the ability to ferment xylose which comprises 20-35% of lignocellulose. Naturally xylose-fermenting yeast such as Pichia stipitis is much more sensitive to inhibitors than S. cerevisiae and it requires accurately controlled microaerophilic conditions during the xylose fermentation, rendering the process technically difficult and expensive. In this study, a novel xylose fermenting yeast Spathaspora passalidarum displayed fast cell growth and efficient xylose fermentation under anaerobic conditions. In contrast, P. stipitis was almost unable to utilize xylose under the same conditions. It is further demonstrated that S. passalidarum converts xylose by means of NADH-preferred xylose reductase (XR) and NAD+-dependent xylitol dehydrogenase (XDH). Thus, the capacity of S. passalidarum to utilize xylose under anaerobic conditions is possibly due to a balance between supply and demand of cofactor through this XR-XDH pathway. Only one other XR with NADH preference has been reported so far. Unfortunately, S. passalidarum also has a low tolerance towards inhibitors generated during pretreatment, which prevents immediate use of this yeast in industrial application. S. passalidarum is able to convert the inhibitor furfural to furfuryl alcohol in a synthetic medium when the addition of furfural is low. The enzymes

  16. Experimental evolution in budding yeast

    Science.gov (United States)

    Murray, Andrew

    2012-02-01

    I will discuss our progress in analyzing evolution in the budding yeast, Saccharomyces cerevisiae. We take two basic approaches. The first is to try and examine quantitative aspects of evolution, for example by determining how the rate of evolution depends on the mutation rate and the population size or asking whether the rate of mutation is uniform throughout the genome. The second is to try to evolve qualitatively novel, cell biologically interesting phenotypes and track the mutations that are responsible for the phenotype. Our efforts include trying to alter cell morphology, evolve multicellularity, and produce a biological oscillator.

  17. Chemostat Culture for Yeast Physiology.

    Science.gov (United States)

    Kerr, Emily O; Dunham, Maitreya J

    2017-07-05

    The use of chemostat culture facilitates the careful comparison of different yeast strains growing in well-defined conditions. Variations in physiology can be measured by examining gene expression, metabolite levels, protein content, and cell morphology. In this protocol, we show how a combination of sample types can be collected during harvest from a single 20-mL chemostat in a ministat array, with special attention to coordinating the handling of the most time-sensitive sample types. © 2017 Cold Spring Harbor Laboratory Press.

  18. Osmotic stress response in the wine yeast Dekkera bruxellensis.

    Science.gov (United States)

    Galafassi, Silvia; Toscano, Marco; Vigentini, Ileana; Piškur, Jure; Compagno, Concetta

    2013-12-01

    Dekkera bruxellensis is mainly associated with lambic beer fermentation and wine production and may contribute in a positive or negative manner to the flavor development. This yeast is able to produce phenolic compounds, such as 4-ethylguaiacol and 4-ethylphenol which could spoil the wine, depending on their concentration. In this work we have investigated how this yeast responds when exposed to conditions causing osmotic stress, as high sorbitol or salt concentrations. We observed that osmotic stress determined the production and accumulation of intracellular glycerol, and the expression of NADH-dependent glycerol-3-phosphate dehydrogenase (GPD) activity was elevated. The involvement of the HOG MAPK pathway in response to this stress condition was also investigated. We show that in D. bruxellensis Hog1 protein is activated by phosphorylation under hyperosmotic conditions, highlighting the conserved role of HOG MAP kinase signaling pathway in the osmotic stress response. Gene Accession numbers in GenBank: DbHOG1: JX65361, DbSTL1: JX965362. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Activation and binding of opsonic fragments of C3 on encapsulated Cryptococcus neoformans by using an alternative complement pathway reconstituted from six isolated proteins.

    Science.gov (United States)

    Kozel, T R; Wilson, M A; Pfrommer, G S; Schlageter, A M

    1989-07-01

    Encapsulated Cryptococcus neoformans yeast cells are potent activators of the complement system. We examined the interaction of the yeast cells with an alternative complement pathway reconstituted from isolated factor D, factor B, factor H, factor I, C3, and properdin. Incubation of encapsulated cryptococci with the reconstituted pathway led to activation and binding of C3 fragments to the yeast cells that was quantitatively and qualitatively identical to that observed with normal human serum. Incubation with either normal serum or a mixture of isolated proteins led to binding of 4 x 10(7) to 5 x 10(7) C3 molecules to the yeast cells. The kinetics for activation and binding of C3 were identical, with maximum binding observed after a 20-min incubation. Immunoglobulin G was not needed for optimal activation kinetics. C3 fragments eluted from the yeast cells by treatment with hydroxylamine and subsequent analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated the presence primarily of iC3b on yeast cells incubated with either normal serum or the reconstituted pathway. Ultrastructural examination of the opsonized yeast cells showed that the cryptococcal capsule was the site for binding of C3 activated from normal serum or the reconstituted pathway, with a dense accumulation of C3 at the periphery of the capsule. Thus, incubation of encapsulated cryptococci in the reconstituted pathway led to deposition of opsonic complement fragments at a site that was appropriate for interaction with phagocyte receptors. Cryptococci opsonized with the reconstituted pathway showed a markedly enhanced interaction with cultured human monocytes compared with unopsonized yeast cells, indicating that the alternative pathway alone is opsonic for yeast cells. However, the results indicate that additional serum factors are needed for optimal opsonization of yeast cells because a 35% reduction in the number of cryptococci bound to macrophages was observed with

  20. Wood ethanol and synthetic natural gas pathways

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-11-30

    This report provided details of updates to the wood ethanol pathway recently added to the GHGenius model, an analytical tool used to analyze emissions from conventional and alternative fuel combustion processes. The pathway contains data developed by the United States Department of Energy. A number of co-products were added to the wood and agricultural residue pathways, including furfural, xylitol, lignin, and glycerol. New chemical inputs included nitrogen gas, ammonia, enzymes and yeast. Biological ethanol pathways were reviewed, and separate inputs for wood, agricultural residues, corn ethanol, and wheat ethanol were added. The model was updated to reflect current research conducted on the gasification of wood and the upgrading of the gas to produce pipeline quality natural gas. New process developments in producing pipeline quality gas from coal were also added. The ability to model enzyme consumption was added to all ethanol pathways. 25 refs., 41 tabs., 8 figs.

  1. Wood ethanol and synthetic natural gas pathways

    International Nuclear Information System (INIS)

    2006-01-01

    This report provided details of updates to the wood ethanol pathway recently added to the GHGenius model, an analytical tool used to analyze emissions from conventional and alternative fuel combustion processes. The pathway contains data developed by the United States Department of Energy. A number of co-products were added to the wood and agricultural residue pathways, including furfural, xylitol, lignin, and glycerol. New chemical inputs included nitrogen gas, ammonia, enzymes and yeast. Biological ethanol pathways were reviewed, and separate inputs for wood, agricultural residues, corn ethanol, and wheat ethanol were added. The model was updated to reflect current research conducted on the gasification of wood and the upgrading of the gas to produce pipeline quality natural gas. New process developments in producing pipeline quality gas from coal were also added. The ability to model enzyme consumption was added to all ethanol pathways. 25 refs., 41 tabs., 8 figs

  2. 1+1 = 3: a fusion of 2 enzymes in the methionine salvage pathway of Tetrahymena thermophila creates a trifunctional enzyme that catalyzes 3 steps in the pathway.

    Directory of Open Access Journals (Sweden)

    Hannah M W Salim

    2009-10-01

    Full Text Available The methionine salvage pathway is responsible for regenerating methionine from its derivative, methylthioadenosine. The complete set of enzymes of the methionine pathway has been previously described in bacteria. Despite its importance, the pathway has only been fully described in one eukaryotic organism, yeast. Here we use a computational approach to identify the enzymes of the methionine salvage pathway in another eukaryote, Tetrahymena thermophila. In this organism, the pathway has two fused genes, MTNAK and MTNBD. Each of these fusions involves two different genes whose products catalyze two different single steps of the pathway in other organisms. One of the fusion proteins, mtnBD, is formed by enzymes that catalyze non-consecutive steps in the pathway, mtnB and mtnD. Interestingly the gene that codes for the intervening enzyme in the pathway, mtnC, is missing from the genome of Tetrahymena. We used complementation tests in yeast to show that the fusion of mtnB and mtnD from Tetrahymena is able to do in one step what yeast does in three, since it can rescue yeast knockouts of mtnB, mtnC, or mtnD. Fusion genes have proved to be very useful in aiding phylogenetic reconstructions and in the functional characterization of genes. Our results highlight another characteristic of fusion proteins, namely that these proteins can serve as biochemical shortcuts, allowing organisms to completely bypass steps in biochemical pathways.

  3. Biodiesel generation from oleaginous yeast Rhodotorula glutinis ...

    African Journals Online (AJOL)

    Biodiesel generation from oleaginous yeast Rhodotorula glutinis with xylose assimilating capacity. ... Biodiesel generation from oleaginous yeast Rhodotorula glutinis with xylose assimilating capacity. C Dai, J Tao, F Xie, Y Dai, M Zhao. Abstract. This study explored a strategy to convert agricultural and forestry residues into ...

  4. Yeasts in sustainable bioethanol production: A review.

    Science.gov (United States)

    Mohd Azhar, Siti Hajar; Abdulla, Rahmath; Jambo, Siti Azmah; Marbawi, Hartinie; Gansau, Jualang Azlan; Mohd Faik, Ainol Azifa; Rodrigues, Kenneth Francis

    2017-07-01

    Bioethanol has been identified as the mostly used biofuel worldwide since it significantly contributes to the reduction of crude oil consumption and environmental pollution. It can be produced from various types of feedstocks such as sucrose, starch, lignocellulosic and algal biomass through fermentation process by microorganisms. Compared to other types of microoganisms, yeasts especially Saccharomyces cerevisiae is the common microbes employed in ethanol production due to its high ethanol productivity, high ethanol tolerance and ability of fermenting wide range of sugars. However, there are some challenges in yeast fermentation which inhibit ethanol production such as high temperature, high ethanol concentration and the ability to ferment pentose sugars. Various types of yeast strains have been used in fermentation for ethanol production including hybrid, recombinant and wild-type yeasts. Yeasts can directly ferment simple sugars into ethanol while other type of feedstocks must be converted to fermentable sugars before it can be fermented to ethanol. The common processes involves in ethanol production are pretreatment, hydrolysis and fermentation. Production of bioethanol during fermentation depends on several factors such as temperature, sugar concentration, pH, fermentation time, agitation rate, and inoculum size. The efficiency and productivity of ethanol can be enhanced by immobilizing the yeast cells. This review highlights the different types of yeast strains, fermentation process, factors affecting bioethanol production and immobilization of yeasts for better bioethanol production.

  5. The wine and beer yeast Dekkera bruxellensis.

    Science.gov (United States)

    Schifferdecker, Anna Judith; Dashko, Sofia; Ishchuk, Olena P; Piškur, Jure

    2014-09-01

    Recently, the non-conventional yeast Dekkera bruxellensis has been gaining more and more attention in the food industry and academic research. This yeast species is a distant relative of Saccharomyces cerevisiae and is especially known for two important characteristics: on the one hand, it is considered to be one of the main spoilage organisms in the wine and bioethanol industry; on the other hand, it is 'indispensable' as a contributor to the flavour profile of Belgium lambic and gueuze beers. Additionally, it adds to the characteristic aromatic properties of some red wines. Recently this yeast has also become a model for the study of yeast evolution. In this review we focus on the recently developed molecular and genetic tools, such as complete genome sequencing and transformation, to study and manipulate this yeast. We also focus on the areas that are particularly well explored in this yeast, such as the synthesis of off-flavours, yeast detection methods, carbon metabolism and evolutionary history. © 2014 The Authors. Yeast published by John Wiley & Sons, Ltd.

  6. Biodiesel generation from oleaginous yeast Rhodotorula glutinis ...

    African Journals Online (AJOL)

    SERVER

    2007-09-19

    Sep 19, 2007 ... This study explored a strategy to convert agricultural and forestry residues into microbial lipid, which could be further transformed into biodiesel. Among the 250 yeast strains screened for xylose assimilating capacity, eight oleaginous yeasts were selected by Sudan Black B test. The lipid content of these 8 ...

  7. 21 CFR 73.355 - Phaffia yeast.

    Science.gov (United States)

    2010-04-01

    ... stabilized color additive mixture. Color additive mixtures for fish feed use made with phaffia yeast may... additive mixtures for coloring foods. (b) Specifications. Phaffia yeast shall conform to the following... § 501.4 of this chapter. (3) The presence of the color additive in salmonid fish that have been fed...

  8. Biosynthesis of polyhydroxyalkanotes in wildtype yeasts | Desuoky ...

    African Journals Online (AJOL)

    Biosynthesis of the biodegradable polymers polyhydroxyalkanotes (PHAs) are studied extensively in wild type and genetically modified prokaryotic cells, however the content and structure of PHA in wild type yeasts are not well documented. The purpose of this study was to screen forty yeast isolates collected from different ...

  9. Virgin olive oil yeasts: A review.

    Science.gov (United States)

    Ciafardini, Gino; Zullo, Biagi Angelo

    2018-04-01

    This review summarizes current knowledge on virgin olive oil yeasts. Newly produced olive oil contains solid particles and micro drops of vegetation water in which yeasts reproduce to become the typical microbiota of olive oil. To date, about seventeen yeast species have been isolated from different types of olive oils and their by-products, of which six species have been identified as new species. Certain yeast species contribute greatly to improving the sensorial characteristics of the newly produced olive oil, whereas other species are considered harmful as they can damage the oil quality through the production of unpleasant flavors and triacylglycerol hydrolysis. Studies carried out in certain yeast strains have demonstrated the presence of defects in olive oil treated with Candida adriatica, Nakazawaea wickerhamii and Candida diddensiae specific strains, while other olive oil samples treated with other Candida diddensiae strains were defect-free after four months of storage and categorized as extra virgin. A new acetic acid producing yeast species, namely, Brettanomyces acidodurans sp. nov., which was recently isolated from olive oil, could be implicated in the wine-vinegary defect of the product. Other aspects related to the activity of the lipase-producing yeasts and the survival of the yeast species in the flavored olive oils are also discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Yeasts in sustainable bioethanol production: A review

    Directory of Open Access Journals (Sweden)

    Siti Hajar Mohd Azhar

    2017-07-01

    Full Text Available Bioethanol has been identified as the mostly used biofuel worldwide since it significantly contributes to the reduction of crude oil consumption and environmental pollution. It can be produced from various types of feedstocks such as sucrose, starch, lignocellulosic and algal biomass through fermentation process by microorganisms. Compared to other types of microoganisms, yeasts especially Saccharomyces cerevisiae is the common microbes employed in ethanol production due to its high ethanol productivity, high ethanol tolerance and ability of fermenting wide range of sugars. However, there are some challenges in yeast fermentation which inhibit ethanol production such as high temperature, high ethanol concentration and the ability to ferment pentose sugars. Various types of yeast strains have been used in fermentation for ethanol production including hybrid, recombinant and wild-type yeasts. Yeasts can directly ferment simple sugars into ethanol while other type of feedstocks must be converted to fermentable sugars before it can be fermented to ethanol. The common processes involves in ethanol production are pretreatment, hydrolysis and fermentation. Production of bioethanol during fermentation depends on several factors such as temperature, sugar concentration, pH, fermentation time, agitation rate, and inoculum size. The efficiency and productivity of ethanol can be enhanced by immobilizing the yeast cells. This review highlights the different types of yeast strains, fermentation process, factors affecting bioethanol production and immobilization of yeasts for better bioethanol production.

  11. Mechanisms by Which Different Functional States of Mitochondria Define Yeast Longevity

    Science.gov (United States)

    Beach, Adam; Leonov, Anna; Arlia-Ciommo, Anthony; Svistkova, Veronika; Lutchman, Vicky; Titorenko, Vladimir I.

    2015-01-01

    Mitochondrial functionality is vital to organismal physiology. A body of evidence supports the notion that an age-related progressive decline in mitochondrial function is a hallmark of cellular and organismal aging in evolutionarily distant eukaryotes. Studies of the baker’s yeast Saccharomyces cerevisiae, a unicellular eukaryote, have led to discoveries of genes, signaling pathways and chemical compounds that modulate longevity-defining cellular processes in eukaryotic organisms across phyla. These studies have provided deep insights into mechanistic links that exist between different traits of mitochondrial functionality and cellular aging. The molecular mechanisms underlying the essential role of mitochondria as signaling organelles in yeast aging have begun to emerge. In this review, we discuss recent progress in understanding mechanisms by which different functional states of mitochondria define yeast longevity, outline the most important unanswered questions and suggest directions for future research. PMID:25768339

  12. Bioactive Compounds Derived from the Yeast Metabolism of Aromatic Amino Acids during Alcoholic Fermentation

    Directory of Open Access Journals (Sweden)

    Albert Mas

    2014-01-01

    Full Text Available Metabolites resulting from nitrogen metabolism in yeast are currently found in some fermented beverages such as wine and beer. Their study has recently attracted the attention of researchers. Some metabolites derived from aromatic amino acids are bioactive compounds that can behave as hormones or even mimic their role in humans and may also act as regulators in yeast. Although the metabolic pathways for their formation are well known, the physiological significance is still far from being understood. The understanding of this relevance will be a key element in managing the production of these compounds under controlled conditions, to offer fermented food with specific enrichment in these compounds or even to use the yeast as nutritional complements.

  13. Characterization of yeast mutants lacking alkaline ceramidases YPC1 and YDC1

    DEFF Research Database (Denmark)

    Voynova, Natalia S; Mallela, Shamroop K; Vazquez, Hector M

    2014-01-01

    Humans and yeast possess alkaline ceramidases located in the early secretory pathway. Single deletions of the highly homologous yeast alkaline ceramidases YPC1 and YDC1 have very little genetic interactions or phenotypes. Here, we performed chemical-genetic screens to find deletions...... reduces chronological life span. A novel finding is that, when working backwards as a ceramide synthase in vivo, Ypc1p prefers C24 and C26 fatty acids as substrates, whereas it prefers C16:0, when solubilized in detergent and working in vitro. Therefore, its physiological activity may not only concern...... the minor ceramides containing C14 and C16. Intriguingly, so far the sole discernable benefit of conserving YPC1 for yeast resides with its ability to convey relative resistance toward H2 O2 ....

  14. Mechanisms by Which Different Functional States of Mitochondria Define Yeast Longevity

    Directory of Open Access Journals (Sweden)

    Adam Beach

    2015-03-01

    Full Text Available Mitochondrial functionality is vital to organismal physiology. A body of evidence supports the notion that an age-related progressive decline in mitochondrial function is a hallmark of cellular and organismal aging in evolutionarily distant eukaryotes. Studies of the baker’s yeast Saccharomyces cerevisiae, a unicellular eukaryote, have led to discoveries of genes, signaling pathways and chemical compounds that modulate longevity-defining cellular processes in eukaryotic organisms across phyla. These studies have provided deep insights into mechanistic links that exist between different traits of mitochondrial functionality and cellular aging. The molecular mechanisms underlying the essential role of mitochondria as signaling organelles in yeast aging have begun to emerge. In this review, we discuss recent progress in understanding mechanisms by which different functional states of mitochondria define yeast longevity, outline the most important unanswered questions and suggest directions for future research.

  15. Yeast-yeast interactions revealed by aromatic profile analysis of Sauvignon Blanc wine fermented by single or co-culture of non-Saccharomyces and Saccharomyces yeasts.

    Science.gov (United States)

    Sadoudi, Mohand; Tourdot-Maréchal, Raphaëlle; Rousseaux, Sandrine; Steyer, Damien; Gallardo-Chacón, Joan-Josep; Ballester, Jordi; Vichi, Stefania; Guérin-Schneider, Rémi; Caixach, Josep; Alexandre, Hervé

    2012-12-01

    There has been increasing interest in the use of selected non-Saccharomyces yeasts in co-culture with Saccharomyces cerevisiae. The main reason is that the multistarter fermentation process is thought to simulate indigenous fermentation, thus increasing wine aroma complexity while avoiding the risks linked to natural fermentation. However, multistarter fermentation is characterised by complex and largely unknown interactions between yeasts. Consequently the resulting wine quality is rather unpredictable. In order to better understand the interactions that take place between non-Saccharomyces and Saccharomyces yeasts during alcoholic fermentation, we analysed the volatile profiles of several mono-culture and co-cultures. Candida zemplinina, Torulaspora delbrueckii and Metschnikowia pulcherrima were used to conduct fermentations either in mono-culture or in co-culture with S. cerevisiae. Up to 48 volatile compounds belonging to different chemical families were quantified. For the first time, we show that C. zemplinina is a strong producer of terpenes and lactones. We demonstrate by means of multivariate analysis that different interactions exist between the co-cultures studied. We observed a synergistic effect on aromatic compound production when M. pulcherrima was in co-culture with S. cerevisiae. However a negative interaction was observed between C. zemplinina and S. cerevisiae, which resulted in a decrease in terpene and lactone content. These interactions are independent of biomass production. The aromatic profiles of T. delbrueckii and S. cerevisiae in mono-culture and in co-culture are very close, and are biomass-dependent, reflecting a neutral interaction. This study reveals that a whole family of compounds could be altered by such interactions. These results suggest that the entire metabolic pathway is affected by these interactions. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Comet assay on tetraploid yeast cells

    DEFF Research Database (Denmark)

    Rank, Jette; Syberg, Kristian; Jensen, Klara

    2009-01-01

    Tetraploid yeast cells (Saccharomyces cerevisiae) were used in the comet assay with the intention of developing a new, fast and easy assay for detecting environmental genotoxic agents without using higher organisms. Two DNA-damaging chemicals, H2O2 and acrylamide, together with wastewater from...... three municipal treatment plants were tested for their effect on the yeast-cell DNA. The main problem with using yeast in the comet assay is the necessity to degrade the cell wall. This was achieved by using Zymolase 100 T twice during the procedure, since Zymolase 20 T did not open the cell wall....... Analytical problems that arose due to the small amount of DNA in the yeast nuclei in haploid and diploid cells, which contain 13 Mbp and 26 Mbp DNA per cell, respectively, were solved by using tetraploid yeast cells (52 Mbp) instead. DNA damage was shown after exposure to H2O2 and acrylamide. The lowest dose...

  17. Metabolomics-based prediction models of yeast strains for screening of metabolites contributing to ethanol stress tolerance

    Science.gov (United States)

    Hashim, Z.; Fukusaki, E.

    2016-06-01

    The increased demand for clean, sustainable and renewable energy resources has driven the development of various microbial systems to produce biofuels. One of such systems is the ethanol-producing yeast. Although yeast produces ethanol naturally using its native pathways, production yield is low and requires improvement for commercial biofuel production. Moreover, ethanol is toxic to yeast and thus ethanol tolerance should be improved to further enhance ethanol production. In this study, we employed metabolomics-based strategy using 30 single-gene deleted yeast strains to construct multivariate models for ethanol tolerance and screen metabolites that relate to ethanol sensitivity/tolerance. The information obtained from this study can be used as an input for strain improvement via metabolic engineering.

  18. Electron transport chain in a thermotolerant yeast.

    Science.gov (United States)

    Mejía-Barajas, Jorge A; Martínez-Mora, José A; Salgado-Garciglia, Rafael; Noriega-Cisneros, Ruth; Ortiz-Avila, Omar; Cortés-Rojo, Christian; Saavedra-Molina, Alfredo

    2017-04-01

    Yeasts capable of growing and surviving at high temperatures are regarded as thermotolerant. For appropriate functioning of cellular processes and cell survival, the maintenance of an optimal redox state is critical of reducing and oxidizing species. We studied mitochondrial functions of the thermotolerant Kluyveromyces marxianus SLP1 and the mesophilic OFF1 yeasts, through the evaluation of its mitochondrial membrane potential (ΔΨ m ), ATPase activity, electron transport chain (ETC) activities, alternative oxidase activity, lipid peroxidation. Mitochondrial membrane potential and the cytoplasmic free Ca 2+ ions (Ca 2+ cyt) increased in the SLP1 yeast when exposed to high temperature, compared with the mesophilic yeast OFF1. ATPase activity in the mesophilic yeast diminished 80% when exposed to 40° while the thermotolerant SLP1 showed no change, despite an increase in the mitochondrial lipid peroxidation. The SLP1 thermotolerant yeast exposed to high temperature showed a diminution of 33% of the oxygen consumption in state 4. The uncoupled state 3 of oxygen consumption did not change in the mesophilic yeast when it had an increase of temperature, whereas in the thermotolerant SLP1 yeast resulted in an increase of 2.5 times when yeast were grown at 30 o , while a decrease of 51% was observed when it was exposed to high temperature. The activities of the ETC complexes were diminished in the SLP1 when exposed to high temperature, but also it was distinguished an alternative oxidase activity. Our results suggest that the mitochondria state, particularly ETC state, is an important characteristic of the thermotolerance of the SLP1 yeast strain.

  19. Engineering tolerance to industrially relevant stress factors in yeast cell factories

    Science.gov (United States)

    Deparis, Quinten; Claes, Arne; Foulquié-Moreno, Maria R.

    2017-01-01

    Abstract The main focus in development of yeast cell factories has generally been on establishing optimal activity of heterologous pathways and further metabolic engineering of the host strain to maximize product yield and titer. Adequate stress tolerance of the host strain has turned out to be another major challenge for obtaining economically viable performance in industrial production. Although general robustness is a universal requirement for industrial microorganisms, production of novel compounds using artificial metabolic pathways presents additional challenges. Many of the bio-based compounds desirable for production by cell factories are highly toxic to the host cells in the titers required for economic viability. Artificial metabolic pathways also turn out to be much more sensitive to stress factors than endogenous pathways, likely because regulation of the latter has been optimized in evolution in myriads of environmental conditions. We discuss different environmental and metabolic stress factors with high relevance for industrial utilization of yeast cell factories and the experimental approaches used to engineer higher stress tolerance. Improving stress tolerance in a predictable manner in yeast cell factories should facilitate their widespread utilization in the bio-based economy and extend the range of products successfully produced in large scale in a sustainable and economically profitable way. PMID:28586408

  20. Engineering tolerance to industrially relevant stress factors in yeast cell factories.

    Science.gov (United States)

    Deparis, Quinten; Claes, Arne; Foulquié-Moreno, Maria R; Thevelein, Johan M

    2017-06-01

    The main focus in development of yeast cell factories has generally been on establishing optimal activity of heterologous pathways and further metabolic engineering of the host strain to maximize product yield and titer. Adequate stress tolerance of the host strain has turned out to be another major challenge for obtaining economically viable performance in industrial production. Although general robustness is a universal requirement for industrial microorganisms, production of novel compounds using artificial metabolic pathways presents additional challenges. Many of the bio-based compounds desirable for production by cell factories are highly toxic to the host cells in the titers required for economic viability. Artificial metabolic pathways also turn out to be much more sensitive to stress factors than endogenous pathways, likely because regulation of the latter has been optimized in evolution in myriads of environmental conditions. We discuss different environmental and metabolic stress factors with high relevance for industrial utilization of yeast cell factories and the experimental approaches used to engineer higher stress tolerance. Improving stress tolerance in a predictable manner in yeast cell factories should facilitate their widespread utilization in the bio-based economy and extend the range of products successfully produced in large scale in a sustainable and economically profitable way. © FEMS 2017.

  1. Coordinate Regulation of Yeast Sterol Regulatory Element-binding Protein (SREBP) and Mga2 Transcription Factors.

    Science.gov (United States)

    Burr, Risa; Stewart, Emerson V; Espenshade, Peter J

    2017-03-31

    The Mga2 and Sre1 transcription factors regulate oxygen-responsive lipid homeostasis in the fission yeast Schizosaccharomyces pombe in a manner analogous to the mammalian sterol regulatory element-binding protein (SREBP)-1 and SREBP-2 transcription factors. Mga2 and SREBP-1 regulate triacylglycerol and glycerophospholipid synthesis, whereas Sre1 and SREBP-2 regulate sterol synthesis. In mammals, a shared activation mechanism allows for coordinate regulation of SREBP-1 and SREBP-2. In contrast, distinct pathways activate fission yeast Mga2 and Sre1. Therefore, it is unclear whether and how these two related pathways are coordinated to maintain lipid balance in fission yeast. Previously, we showed that Sre1 cleavage is defective in the absence of mga2 Here, we report that this defect is due to deficient unsaturated fatty acid synthesis, resulting in aberrant membrane transport. This defect is recapitulated by treatment with the fatty acid synthase inhibitor cerulenin and is rescued by addition of exogenous unsaturated fatty acids. Furthermore, sterol synthesis inhibition blocks Mga2 pathway activation. Together, these data demonstrate that Sre1 and Mga2 are each regulated by the lipid product of the other transcription factor pathway, providing a source of coordination for these two branches of lipid synthesis. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  2. Calcium homeostasis and signaling in fungi and their relevance for pathogenicity of yeasts and filamentous fungi

    Directory of Open Access Journals (Sweden)

    Renata Tisi

    2016-09-01

    Full Text Available Though fungi show peculiarities in the purposes and specific traits of calcium signaling pathways, the general scheme and the most important players are well conserved if compared to higher eukaryotes. This provides a powerful opportunity either to investigate shared features using yeast as a model or to exploit fungal specificities as potential targets for antifungal therapies. The sequenced genomes from yeast Saccharomyces cerevisiae, Schizosaccharomyces pombe and the filamentous fungus Neurospora crassa were already published more than ten years ago. More recently the genome sequences of filamentous fungi of Aspergillus genus, some of which threatening pathogens, and dimorphic fungi Ustilago maydis were published, giving the chance to identify several proteins involved in calcium signaling based on their homology to yeast or mammalian counterparts. Nonetheless, unidentified calcium transporters are still present in these organisms which await to be molecularly characterized. Despite the relative simplicity in yeast calcium machinery and the availability of sophisticated molecular tools, in the last years, a number of new actors have been identified, albeit not yet fully characterized. This review will try to describe the state of the art in calcium channels and calcium signaling knowledge in yeast, with particular attention to the relevance of this knowledge with respect to pathological fungi.

  3. Implication of Ca2+ in the regulation of replicative life span of budding yeast.

    Science.gov (United States)

    Tsubakiyama, Ryohei; Mizunuma, Masaki; Gengyo, Anri; Yamamoto, Josuke; Kume, Kazunori; Miyakawa, Tokichi; Hirata, Dai

    2011-08-19

    In eukaryotic cells, Ca(2+)-triggered signaling pathways are used to regulate a wide variety of cellular processes. Calcineurin, a highly conserved Ca(2+)/calmodulin-dependent protein phosphatase, plays key roles in the regulation of diverse biological processes in organisms ranging from yeast to humans. We isolated a mutant of the SIR3 gene, implicated in the regulation of life span, as a suppressor of the Ca(2+) sensitivity of zds1Δ cells in the budding yeast Saccharomyces cerevisiae. Therefore, we investigated a relationship between Ca(2+) signaling and life span in yeast. Here we show that Ca(2+) affected the replicative life span (RLS) of yeast. Increased external and intracellular Ca(2+) levels caused a reduction in their RLS. Consistently, the increase in calcineurin activity by either the zds1 deletion or the constitutively activated calcineurin reduced RLS. Indeed, the shortened RLS of zds1Δ cells was suppressed by the calcineurin deletion. Further, the calcineurin deletion per se promoted aging without impairing the gene silencing typically observed in short-lived sir mutants, indicating that calcineurin plays an important role in a regulation of RLS even under normal growth condition. Thus, our results indicate that Ca(2+) homeostasis/Ca(2+) signaling are required to regulate longevity in budding yeast.

  4. Breeding of Freeze-tolerant Yeast and the Mechanisms of Stress-tolerance

    Science.gov (United States)

    Hino, Akihiro

    Frozen dough method have been adopted in the baking industry to reduce labor and to produce fresh breads in stores. New freeze-tolerant yeasts for frozen dough preparations were isolated from banana peel and identified. To obtain strains that have fermentative ability even after several months of frozen storage in fermented dough, we attempted to breed new freeze-tolerantstrain. The hybrid between S.cerevisiae, which is a isolated freeze-tolerant strain, and a strain isolated from bakers' yeast with sexual conjugation gave a good quality bread made from frozen dough method. Freeze-tolerant strains showed higher surviving and trehalose accumulating abilities than freeze-sensitive strains. The freeze tolerance of the yeasts was associated with the basal amount of intracellular trehalose after rapid degradation at the onset of the prefermentation period. The complicated metabolic pathway and the regulation system of trehalose in yeast cells are introduced. The trehalose synthesis may act as a metabolic buffer system which contribute to maintain the intracellular inorganic phosphate and as a feedback regulation system in the glycolysis. However, it is not known enough how the trehalose protects yeast cells from stress.

  5. New Protocol Based on UHPLC-MS/MS for Quantitation of Metabolites in Xylose-Fermenting Yeasts

    Science.gov (United States)

    Campos, Christiane Gonçalves; Veras, Henrique César Teixeira; de Aquino Ribeiro, José Antônio; Costa, Patrícia Pinto Kalil Gonçalves; Araújo, Katiúscia Pereira; Rodrigues, Clenilson Martins; de Almeida, João Ricardo Moreira; Abdelnur, Patrícia Verardi

    2017-12-01

    Xylose fermentation is a bottleneck in second-generation ethanol production. As such, a comprehensive understanding of xylose metabolism in naturally xylose-fermenting yeasts is essential for prospection and construction of recombinant yeast strains. The objective of the current study was to establish a reliable metabolomics protocol for quantification of key metabolites of xylose catabolism pathways in yeast, and to apply this protocol to Spathaspora arborariae. Ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) was used to quantify metabolites, and afterwards, sample preparation was optimized to examine yeast intracellular metabolites. S. arborariae was cultivated using xylose as a carbon source under aerobic and oxygen-limited conditions. Ion pair chromatography (IPC) and hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) were shown to efficiently quantify 14 and 5 metabolites, respectively, in a more rapid chromatographic protocol than previously described. Thirteen and eleven metabolites were quantified in S. arborariae under aerobic and oxygen-limited conditions, respectively. This targeted metabolomics protocol is shown here to quantify a total of 19 metabolites, including sugars, phosphates, coenzymes, monosaccharides, and alcohols, from xylose catabolism pathways (glycolysis, pentose phosphate pathway, and tricarboxylic acid cycle) in yeast. Furthermore, to our knowledge, this is the first time that intracellular metabolites have been quantified in S. arborariae after xylose consumption. The results indicated that fine control of oxygen levels during fermentation is necessary to optimize ethanol production by S. arborariae. The protocol presented here may be applied to other yeast species and could support yeast genetic engineering to improve second generation ethanol production. [Figure not available: see fulltext.

  6. The phytopathogenic virulent effector protein RipI induces apoptosis in budding yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    Deng, Meng-Ying; Sun, Yun-Hao; Li, Pai; Fu, Bei; Shen, Dong; Lu, Yong-Jun

    2016-10-01

    Virulent protein toxins secreted by the bacterial pathogens can cause cytotoxicity by various molecular mechanisms to combat host cell defense. On the other hand, these proteins can also be used as probes to investigate the defense pathway of host innate immunity. Ralstonia solanacearum, one of the most virulent bacterial phytopathogens, translocates more than 70 effector proteins via type III secretion system during infection. Here, we characterized the cytotoxicity of effector RipI in budding yeast Saccharomyce scerevisiae, an alternative host model. We found that over-expression of RipI resulted in severe growth defect and arginine (R) 117 within the predicted integrase motif was required for inhibition of yeast growth. The phenotype of death manifested the hallmarks of apoptosis. Our data also revealed that RipI-induced apoptosis was independent of Yca1 and mitochondria-mediated apoptotic pathways because Δyca1 and Δaif1 were both sensitive to RipI as compared with the wild type. We further demonstrated that RipI was localized in the yeast nucleus and the N-terminal 1-174aa was required for the localization. High-throughput RNA sequencing analysis showed that upon RipI over-expression, 101 unigenes of yeast ribosome presented lower expression level, and 42 GO classes related to the nucleus or recombination were enriched with differential expression levels. Taken together, our data showed that a nuclear-targeting effector RipI triggers yeast apoptosis, potentially dependent on its integrase function. Our results also provided an alternative strategy to dissect the signaling pathway of cytotoxicity induced by the protein toxins. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Functional conservation of coenzyme Q biosynthetic genes among yeasts, plants, and humans.

    Directory of Open Access Journals (Sweden)

    Kazuhiro Hayashi

    Full Text Available Coenzyme Q (CoQ is an essential factor for aerobic growth and oxidative phosphorylation in the electron transport system. The biosynthetic pathway for CoQ has been proposed mainly from biochemical and genetic analyses of Escherichia coli and Saccharomyces cerevisiae; however, the biosynthetic pathway in higher eukaryotes has been explored in only a limited number of studies. We previously reported the roles of several genes involved in CoQ synthesis in the fission yeast Schizosaccharomyces pombe. Here, we expand these findings by identifying ten genes (dps1, dlp1, ppt1, and coq3-9 that are required for CoQ synthesis. CoQ10-deficient S. pombe coq deletion strains were generated and characterized. All mutant fission yeast strains were sensitive to oxidative stress, produced a large amount of sulfide, required an antioxidant to grow on minimal medium, and did not survive at the stationary phase. To compare the biosynthetic pathway of CoQ in fission yeast with that in higher eukaryotes, the ability of CoQ biosynthetic genes from humans and plants (Arabidopsis thaliana to functionally complement the S. pombe coq deletion strains was determined. With the exception of COQ9, expression of all other human and plant COQ genes recovered CoQ10 production by the fission yeast coq deletion strains, although the addition of a mitochondrial targeting sequence was required for human COQ3 and COQ7, as well as A. thaliana COQ6. In summary, this study describes the functional conservation of CoQ biosynthetic genes between yeasts, humans, and plants.

  8. Distinct Domestication Trajectories in Top-Fermenting Beer Yeasts and Wine Yeasts.

    Science.gov (United States)

    Gonçalves, Margarida; Pontes, Ana; Almeida, Pedro; Barbosa, Raquel; Serra, Marta; Libkind, Diego; Hutzler, Mathias; Gonçalves, Paula; Sampaio, José Paulo

    2016-10-24

    Beer is one of the oldest alcoholic beverages and is produced by the fermentation of sugars derived from starches present in cereal grains. Contrary to lager beers, made by bottom-fermenting strains of Saccharomyces pastorianus, a hybrid yeast, ale beers are closer to the ancient beer type and are fermented by S. cerevisiae, a top-fermenting yeast. Here, we use population genomics to investigate (1) the closest relatives of top-fermenting beer yeasts; (2) whether top-fermenting yeasts represent an independent domestication event separate from those already described; (3) whether single or multiple beer yeast domestication events can be inferred; and (4) whether top-fermenting yeasts represent non-recombinant or recombinant lineages. Our results revealed that top-fermenting beer yeasts are polyphyletic, with a main clade composed of at least three subgroups, dominantly represented by the German, British, and wheat beer strains. Other beer strains were phylogenetically close to sake, wine, or bread yeasts. We detected genetic signatures of beer yeast domestication by investigating genes previously linked to brewing and using genome-wide scans. We propose that the emergence of the main clade of beer yeasts is related with a domestication event distinct from the previously known cases of wine and sake yeast domestication. The nucleotide diversity of the main beer clade more than doubled that of wine yeasts, which might be a consequence of fundamental differences in the modes of beer and wine yeast domestication. The higher diversity of beer strains could be due to the more intense and different selection regimes associated to brewing. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. A central role for TOR signalling in a yeast model for juvenile CLN3 disease

    Directory of Open Access Journals (Sweden)

    Michael E. Bond

    2015-11-01

    Full Text Available Yeasts provide an excellent genetically tractable eukaryotic system for investigating the function of genes in their biological context, and are especially relevant for those conserved genes that cause disease. We study the role of btn1, the orthologue of a human gene that underlies an early onset neurodegenerative disease (juvenile CLN3 disease, neuronal ceroid lipofuscinosis (NCLs or Batten disease in the fission yeast Schizosaccharomyces pombe. A global screen for genetic interactions with btn1 highlighted a conserved key signalling hub in which multiple components functionally relate to this conserved disease gene. This signalling hub includes two major mitogen-activated protein kinase (MAPK cascades, and centers on the Tor kinase complexes TORC1 and TORC2. We confirmed that yeast cells modelling CLN3 disease exhibit features consistent with dysfunction in the TORC pathways, and showed that modulating TORC function leads to a comprehensive rescue of defects in this yeast disease model. The same pathways may be novel targets in the development of therapies for the NCLs and related diseases.

  10. Herbicide glufosinate inhibits yeast growth and extends longevity during wine fermentation.

    Science.gov (United States)

    Vallejo, Beatriz; Picazo, Cecilia; Orozco, Helena; Matallana, Emilia; Aranda, Agustín

    2017-09-29

    Glufosinate ammonium (GA) is a widely used herbicide that inhibits glutamine synthetase. This inhibition leads to internal amino acid starvation which, in turn, causes the activation of different nutrient sensing pathways. GA also inhibits the enzyme of the yeast Saccharomyces cerevisiae in such a way that, although it is not used as a fungicide, it may alter yeast performance in industrial processes like winemaking. We describe herein how GA indeed inhibits the yeast growth of a wine strain during the fermentation of grape juice. In turn, GA extends longevity in a variety of growth media. The biochemical analysis indicates that GA partially inhibits the nutrient sensing TORC1 pathway, which may explain these phenotypes. The GCN2 kinase mutant is hypersensitive to GA. Hence the control of translation and amino acid biosynthesis is required to also deal with the damaging effects of this pesticide. A global metabolomics analysis under winemaking conditions indicated that an increase in amino acid and in polyamines occurred. In conclusion, GA affects many different biochemical processes during winemaking, which provides us with some insights into both the effect of this herbicide on yeast physiology and into the relevance of the metabolic step for connecting nitrogen and carbon metabolism.

  11. Engineered CRISPR/Cas9 system for multiplex genome engineering of polyploid industrial yeast strains.

    Science.gov (United States)

    Lian, Jiazhang; Bao, Zehua; Hu, Sumeng; Zhao, Huimin

    2018-06-01

    The CRISPR/Cas9 system has been widely used for multiplex genome engineering of Saccharomyces cerevisiae. However, its application in manipulating industrial yeast strains is less successful, probably due to the genome complexity and low copy numbers of gRNA expression plasmids. Here we developed an efficient CRISPR/Cas9 system for industrial yeast strain engineering by using our previously engineered plasmids with increased copy numbers. Four genes in both a diploid strain (Ethanol Red, 8 alleles in total) and a triploid strain (ATCC 4124, 12 alleles in total) were knocked out in a single step with 100% efficiency. This system was used to construct xylose-fermenting, lactate-producing industrial yeast strains, in which ALD6, PHO13, LEU2, and URA3 were disrupted in a single step followed by the introduction of a xylose utilization pathway and a lactate biosynthetic pathway on auxotrophic marker plasmids. The optimized CRISPR/Cas9 system provides a powerful tool for the development of industrial yeast based microbial cell factories. © 2018 Wiley Periodicals, Inc.

  12. Genomics and the making of yeast biodiversity.

    Science.gov (United States)

    Hittinger, Chris Todd; Rokas, Antonis; Bai, Feng-Yan; Boekhout, Teun; Gonçalves, Paula; Jeffries, Thomas W; Kominek, Jacek; Lachance, Marc-André; Libkind, Diego; Rosa, Carlos A; Sampaio, José Paulo; Kurtzman, Cletus P

    2015-12-01

    Yeasts are unicellular fungi that do not form fruiting bodies. Although the yeast lifestyle has evolved multiple times, most known species belong to the subphylum Saccharomycotina (syn. Hemiascomycota, hereafter yeasts). This diverse group includes the premier eukaryotic model system, Saccharomyces cerevisiae; the common human commensal and opportunistic pathogen, Candida albicans; and over 1000 other known species (with more continuing to be discovered). Yeasts are found in every biome and continent and are more genetically diverse than angiosperms or chordates. Ease of culture, simple life cycles, and small genomes (∼10-20Mbp) have made yeasts exceptional models for molecular genetics, biotechnology, and evolutionary genomics. Here we discuss recent developments in understanding the genomic underpinnings of the making of yeast biodiversity, comparing and contrasting natural and human-associated evolutionary processes. Only a tiny fraction of yeast biodiversity and metabolic capabilities has been tapped by industry and science. Expanding the taxonomic breadth of deep genomic investigations will further illuminate how genome function evolves to encode their diverse metabolisms and ecologies. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Yeast-based biosensors: design and applications.

    Science.gov (United States)

    Adeniran, Adebola; Sherer, Michael; Tyo, Keith E J

    2015-02-01

    Yeast-based biosensing (YBB) is an exciting research area, as many studies have demonstrated the use of yeasts to accurately detect specific molecules. Biosensors incorporating various yeasts have been reported to detect an incredibly large range of molecules including but not limited to odorants, metals, intracellular metabolites, carcinogens, lactate, alcohols, and sugars. We review the detection strategies available for different types of analytes, as well as the wide range of output methods that have been incorporated with yeast biosensors. We group biosensors into two categories: those that are dependent upon transcription of a gene to report the detection of a desired molecule and those that are independent of this reporting mechanism. Transcription-dependent biosensors frequently depend on heterologous expression of sensing elements from non-yeast organisms, a strategy that has greatly expanded the range of molecules available for detection by YBBs. Transcription-independent biosensors circumvent the problem of sensing difficult-to-detect analytes by instead relying on yeast metabolism to generate easily detected molecules when the analyte is present. The use of yeast as the sensing element in biosensors has proven to be successful and continues to hold great promise for a variety of applications. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permission@oup.com.

  14. Accelerating Yeast Prion Biology using Droplet Microfluidics

    Science.gov (United States)

    Ung, Lloyd; Rotem, Assaf; Jarosz, Daniel; Datta, Manoshi; Lindquist, Susan; Weitz, David

    2012-02-01

    Prions are infectious proteins in a misfolded form, that can induce normal proteins to take the misfolded state. Yeast prions are relevant, as a model of human prion diseases, and interesting from an evolutionary standpoint. Prions may also be a form of epigenetic inheritance, which allow yeast to adapt to stressful conditions at rates exceeding those of random mutations and propagate that adaptation to their offspring. Encapsulation of yeast in droplet microfluidic devices enables high-throughput measurements with single cell resolution, which would not be feasible using bulk methods. Millions of populations of yeast can be screened to obtain reliable measurements of prion induction and loss rates. The population dynamics of clonal yeast, when a fraction of the cells are prion expressing, can be elucidated. Furthermore, the mechanism by which certain strains of bacteria induce yeast to express prions in the wild can be deduced. Integrating the disparate fields of prion biology and droplet microfluidics reveals a more complete picture of how prions may be more than just diseases and play a functional role in yeast.

  15. Yeast cell factories on the horizon

    DEFF Research Database (Denmark)

    Nielsen, Jens

    2015-01-01

    For thousands of years, yeast has been used for making beer, bread, and wine. In modern times, it has become a commercial workhorse for producing fuels, chemicals, and pharmaceuticals such as insulin, human serum albumin, and vaccines against hepatitis virus and human papillomavirus. Yeast has also...... been engineered to make chemicals at industrial scale (e.g., succinic acid, lactic acid, resveratrol) and advanced biofuels (e.g., isobutanol) (1). On page 1095 of this issue, Galanie et al. (2) demonstrate that yeast can now be engineered to produce opioids (2), a major class of compounds used...

  16. 21 CFR 172.590 - Yeast-malt sprout extract.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Yeast-malt sprout extract. 172.590 Section 172.590... CONSUMPTION Flavoring Agents and Related Substances § 172.590 Yeast-malt sprout extract. Yeast-malt sprout... prescribed conditions: (a) The additive is produced by partial hydrolysis of yeast extract (derived from...

  17. 21 CFR 184.1983 - Bakers yeast extract.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Bakers yeast extract. 184.1983 Section 184.1983... Listing of Specific Substances Affirmed as GRAS § 184.1983 Bakers yeast extract. (a) Bakers yeast extract... a selected strain of yeast, Saccharomyces cerevisiae. It may be concentrated or dried. (b) The...

  18. 21 CFR 172.898 - Bakers yeast glycan.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Bakers yeast glycan. 172.898 Section 172.898 Food... Multipurpose Additives § 172.898 Bakers yeast glycan. Bakers yeast glycan may be safely used in food in accordance with the following conditions: (a) Bakers yeast glycan is the comminuted, washed, pasteurized, and...

  19. Industrial brewing yeast engineered for the production of primary flavor determinants in hopped beer.

    Science.gov (United States)

    Denby, Charles M; Li, Rachel A; Vu, Van T; Costello, Zak; Lin, Weiyin; Chan, Leanne Jade G; Williams, Joseph; Donaldson, Bryan; Bamforth, Charles W; Petzold, Christopher J; Scheller, Henrik V; Martin, Hector Garcia; Keasling, Jay D

    2018-03-20

    Flowers of the hop plant provide both bitterness and "hoppy" flavor to beer. Hops are, however, both a water and energy intensive crop and vary considerably in essential oil content, making it challenging to achieve a consistent hoppy taste in beer. Here, we report that brewer's yeast can be engineered to biosynthesize aromatic monoterpene molecules that impart hoppy flavor to beer by incorporating recombinant DNA derived from yeast, mint, and basil. Whereas metabolic engineering of biosynthetic pathways is commonly enlisted to maximize product titers, tuning expression of pathway enzymes to affect target production levels of multiple commercially important metabolites without major collateral metabolic changes represents a unique challenge. By applying state-of-the-art engineering techniques and a framework to guide iterative improvement, strains are generated with target performance characteristics. Beers produced using these strains are perceived as hoppier than traditionally hopped beers by a sensory panel in a double-blind tasting.

  20. Immobilization of yeast cells by radiation-induced polymerization

    International Nuclear Information System (INIS)

    Fujimura, T.; Kaetsu, I.

    1982-01-01

    Radiation-induced polymerization method was applied to the immobilization of yeast cells. The effects of irradiation, cooling and monomer, which are neccessary for polymerization, were recovered completely by subsequent aerobical incubation of yeast cells. The ethanol productive in immobilized yeast cells increased with the increase of aerobical incubation period. The growth of yeast cells in immobilized yeast cells was indicated. The maximum ethanol productivity in immobilized yeast cell system was around three times as much as that in free yeast cell system. (orig.)

  1. Improved vanillin production in baker's yeast through in silico design.

    Science.gov (United States)

    Brochado, Ana Rita; Matos, Claudia; Møller, Birger L; Hansen, Jørgen; Mortensen, Uffe H; Patil, Kiran Raosaheb

    2010-11-08

    Vanillin is one of the most widely used flavouring agents, originally obtained from cured seed pods of the vanilla orchid Vanilla planifolia. Currently vanillin is mostly produced via chemical synthesis. A de novo synthetic pathway for heterologous vanillin production from glucose has recently been implemented in baker's yeast, Saccharamyces cerevisiae. In this study we aimed at engineering this vanillin cell factory towards improved productivity and thereby at developing an attractive alternative to chemical synthesis. Expression of a glycosyltransferase from Arabidopsis thaliana in the vanillin producing S. cerevisiae strain served to decrease product toxicity. An in silico metabolic engineering strategy of this vanillin glucoside producing strain was designed using a set of stoichiometric modelling tools applied to the yeast genome-scale metabolic network. Two targets (PDC1 and GDH1) were selected for experimental verification resulting in four engineered strains. Three of the mutants showed up to 1.5 fold higher vanillin β-D-glucoside yield in batch mode, while continuous culture of the Δpdc1 mutant showed a 2-fold productivity improvement. This mutant presented a 5-fold improvement in free vanillin production compared to the previous work on de novo vanillin biosynthesis in baker's yeast. Use of constraints corresponding to different physiological states was found to greatly influence the target predictions given minimization of metabolic adjustment (MOMA) as biological objective function. In vivo verification of the targets, selected based on their predicted metabolic adjustment, successfully led to overproducing strains. Overall, we propose and demonstrate a framework for in silico design and target selection for improving microbial cell factories.

  2. Improved vanillin production in baker's yeast through in silico design

    Science.gov (United States)

    2010-01-01

    Background Vanillin is one of the most widely used flavouring agents, originally obtained from cured seed pods of the vanilla orchid Vanilla planifolia. Currently vanillin is mostly produced via chemical synthesis. A de novo synthetic pathway for heterologous vanillin production from glucose has recently been implemented in baker's yeast, Saccharamyces cerevisiae. In this study we aimed at engineering this vanillin cell factory towards improved productivity and thereby at developing an attractive alternative to chemical synthesis. Results Expression of a glycosyltransferase from Arabidopsis thaliana in the vanillin producing S. cerevisiae strain served to decrease product toxicity. An in silico metabolic engineering strategy of this vanillin glucoside producing strain was designed using a set of stoichiometric modelling tools applied to the yeast genome-scale metabolic network. Two targets (PDC1 and GDH1) were selected for experimental verification resulting in four engineered strains. Three of the mutants showed up to 1.5 fold higher vanillin β-D-glucoside yield in batch mode, while continuous culture of the Δpdc1 mutant showed a 2-fold productivity improvement. This mutant presented a 5-fold improvement in free vanillin production compared to the previous work on de novo vanillin biosynthesis in baker's yeast. Conclusion Use of constraints corresponding to different physiological states was found to greatly influence the target predictions given minimization of metabolic adjustment (MOMA) as biological objective function. In vivo verification of the targets, selected based on their predicted metabolic adjustment, successfully led to overproducing strains. Overall, we propose and demonstrate a framework for in silico design and target selection for improving microbial cell factories. PMID:21059201

  3. The global transcriptional response of fission yeast to hydrogen sulfide.

    Directory of Open Access Journals (Sweden)

    Xu Jia

    Full Text Available BACKGROUND: Hydrogen sulfide (H(2S is a newly identified member of the small family of gasotransmitters that are endogenous gaseous signaling molecules that have a fundamental role in human biology and disease. Although it is a relatively recent discovery and the mechanism of H(2S activity is not completely understood, it is known to be involved in a number of cellular processes; H(2S can affect ion channels, transcription factors and protein kinases in mammals. METHODOLOGY/PRINCIPAL FINDINGS: In this paper, we have used fission yeast as a model organism to study the global gene expression profile in response to H(2S by microarray. We initially measured the genome-wide transcriptional response of fission yeast to H(2S. Through the functional classification of genes whose expression profile changed in response to H(2S, we found that H(2S mainly influences genes that encode putative or known stress proteins, membrane transporters, cell cycle/meiotic proteins, transcription factors and respiration protein in the mitochondrion. Our analysis showed that there was a significant overlap between the genes affected by H(2S and the stress response. We identified that the target genes of the MAPK pathway respond to H(2S; we also identified that a number of transporters respond to H(2S, these include sugar/carbohydrate transporters, ion transporters, and amino acid transporters. We found many mitochondrial genes to be down regulated upon H(2S treatment and that H(2S can reduce mitochondrial oxygen consumption. CONCLUSION/SIGNIFICANCE: This study identifies potential molecular targets of the signaling molecule H(2S in fission yeast and provides clues about the identity of homologues human proteins and will further the understanding of the cellular role of H(2S in human diseases.

  4. Improved vanillin production in baker's yeast through in silico design

    Directory of Open Access Journals (Sweden)

    Hansen Jørgen

    2010-11-01

    Full Text Available Abstract Background Vanillin is one of the most widely used flavouring agents, originally obtained from cured seed pods of the vanilla orchid Vanilla planifolia. Currently vanillin is mostly produced via chemical synthesis. A de novo synthetic pathway for heterologous vanillin production from glucose has recently been implemented in baker's yeast, Saccharamyces cerevisiae. In this study we aimed at engineering this vanillin cell factory towards improved productivity and thereby at developing an attractive alternative to chemical synthesis. Results Expression of a glycosyltransferase from Arabidopsis thaliana in the vanillin producing S. cerevisiae strain served to decrease product toxicity. An in silico metabolic engineering strategy of this vanillin glucoside producing strain was designed using a set of stoichiometric modelling tools applied to the yeast genome-scale metabolic network. Two targets (PDC1 and GDH1 were selected for experimental verification resulting in four engineered strains. Three of the mutants showed up to 1.5 fold higher vanillin β-D-glucoside yield in batch mode, while continuous culture of the Δpdc1 mutant showed a 2-fold productivity improvement. This mutant presented a 5-fold improvement in free vanillin production compared to the previous work on de novo vanillin biosynthesis in baker's yeast. Conclusion Use of constraints corresponding to different physiological states was found to greatly influence the target predictions given minimization of metabolic adjustment (MOMA as biological objective function. In vivo verification of the targets, selected based on their predicted metabolic adjustment, successfully led to overproducing strains. Overall, we propose and demonstrate a framework for in silico design and target selection for improving microbial cell factories.

  5. Fatty acids from oleaginous yeasts and yeast-like fungi and their potential applications.

    Science.gov (United States)

    Xue, Si-Jia; Chi, Zhe; Zhang, Yu; Li, Yan-Feng; Liu, Guang-Lei; Jiang, Hong; Hu, Zhong; Chi, Zhen-Ming

    2018-02-01

    Oleaginous yeasts, fatty acids biosynthesis and regulation in the oleaginous yeasts and the fatty acids from the oleaginous yeasts and their applications are reviewed in this article. Oleaginous yeasts such as Rhodosporidium toruloides, Yarrowia lipolytica, Rhodotorula mucilaginosa, and Aureobasidium melanogenum, which can accumulate over 50% lipid of their cell dry weight, have many advantages over other oleaginous microorganisms. The fatty acids from the oleaginous yeasts have many potential applications. Many oleaginous yeasts have now been genetically modified to over-produce fatty acids and their derivatives. The most important features of the oleaginous yeasts are that they have special enzymatic systems for enhanced biosynthesis and regulation of fatty acids in their lipid particles. Recently, some oleaginous yeasts such as R. toruloides have been found to have a unique fatty acids synthetase and other oleaginous yeasts such as A. melanogenum have a unique highly reducing polyketide synthase (HR-PKS) involved in the biosynthesis of hydroxyl fatty acids. It is necessary to further enhance lipid biosynthesis using metabolic engineering and explore new applications of fatty acids in biotechnology.

  6. Endosomal protein sorting and autophagy genes contribute to the regulation of yeast life span.

    Science.gov (United States)

    Longo, Valter D; Nislow, Corey; Fabrizio, Paola

    2010-11-01

    Accumulating evidence from various organisms points to a role for autophagy in the regulation of life span. By performing a genome-wide screen to identify novel life span determinants in Saccharomyces cerevisiae, we have obtained further insights into the autophagy-related and -unrelated degradation processes that may be important for preventing cellular senescence. The generation of multivesicular bodies and their fusion with the vacuole in the endosomal pathway emerged as novel cell functions involved in yeast chronological survival and longevity extension.

  7. Comparison of Nitrogen Depletion and Repletion on Lipid Production in Yeast and Fungal Species

    Directory of Open Access Journals (Sweden)

    Shihui Yang

    2016-08-01

    Full Text Available Although it is well known that low nitrogen stimulates lipid accumulation, especially for algae and some oleaginous yeast, few studies have been conducted in fungal species, especially on the impact of different nitrogen deficiency strategies. In this study, we use two promising consolidated bioprocessing (CBP candidates to examine the impact of two nitrogen deficiency strategies on lipid production, which are the extensively investigated oleaginous yeast Yarrowia lipolytica, and the commercial cellulase producer Trichoderma reesei. We first utilized bioinformatics approaches to reconstruct the fatty acid metabolic pathway and demonstrated the presence of a triacylglycerol (TAG biosynthesis pathway in Trichoderma reesei. We then examined the lipid production of Trichoderma reesei and Y. lipomyces in different media using two nitrogen deficiency strategies of nitrogen natural repletion and nitrogen depletion through centrifugation. Our results demonstrated that nitrogen depletion was better than nitrogen repletion with about 30% lipid increase for Trichoderma reesei and Y. lipomyces, and could be an option to improve lipid production in both oleaginous yeast and filamentous fungal species. The resulting distinctive lipid composition profiles indicated that the impacts of nitrogen depletion on yeast were different from those for fungal species. Under three types of C/N ratio conditions, C16 and C18 fatty acids were the predominant forms of lipids for both Trichoderma reesei and Y. lipolytica. While the overall fatty acid methyl ester (FAME profiles of Trichoderma reesei were similar, the overall FAME profiles of Y. lipolytica observed a shift. The fatty acid metabolic pathway reconstructed in this work supports previous reports of lipid production in T. reesei, and provides a pathway for future omics studies and metabolic engineering efforts. Further investigation to identify the genetic targets responsible for the effect of nitrogen depletion on

  8. Sterol composition of yeast organelle membranes and subcellular distribution of enzymes involved in sterol metabolism.

    OpenAIRE

    Zinser, E; Paltauf, F; Daum, G

    1993-01-01

    Organelles of the yeast Saccharomyces cerevisiae were isolated and analyzed for sterol composition and the activity of three enzymes involved in sterol metabolism. The plasma membrane and secretory vesicles, the fractions with the highest sterol contents, contain ergosterol as the major sterol. In other subcellular membranes, which exhibit lower sterol contents, intermediates of the sterol biosynthetic pathway were found at higher percentages. Lipid particles contain, in addition to ergostero...

  9. Isolation and identification of radiation resistant yeasts from sea water

    International Nuclear Information System (INIS)

    Park, Jong Cheon; Jeong, Yong Uk; Kim, Du Hong; Jo, Eun A

    2011-12-01

    This study was conducted to isolate radiation-resistant yeasts from sea water for development of application technology of radiation-resistant microorganism. · Isolation of 656 yeasts from sea water and selection of 2 radiation-resistant yeasts (D 10 value >3) · Identification of isolated yeasts as Filobasidium elegans sharing 99% sequence similarity · Characterization of isolated yeast with ability to repair of the DNA damage and membrane integrity to irradiation

  10. Activation of waste brewer's yeast Saccharomyces cerevisiae for bread production

    OpenAIRE

    Popov Stevan D.; Dodić Siniša N.; Mastilović Jasna S.; Dodić Jelena M.; Popov-Raljić Jovanka V.

    2005-01-01

    The waste brewer's yeast S. cerevisiae (activated and non-activated) was compared with the commercial baker's yeast regarding the volume of developed gas in dough, volume and freshness stability of produced bread. The activation of waste brewer's yeast resulted in the increased volume of developed gas in dough by 100% compared to non-activated brewer's yeast, and the obtained bread is of more stable freshness compared to bread produced with baker's yeast. The activation of BY affects positive...

  11. Propagation of Mammalian Prions in Yeast

    National Research Council Canada - National Science Library

    Harris, David A

    2006-01-01

    ...: the budding yeast Saccharomyces cerevisiae. This unicellular organism offers a number of potential advantages for the study of prion biology, including rapid generation time, ease of culturing, and facile genetics...

  12. Structure and function of yeast alcohol dehydrogenase

    Directory of Open Access Journals (Sweden)

    VLADIMIR LESKOVAC

    2000-04-01

    Full Text Available 1. Introduction 2. Isoenzymes of YADH 3. Substrate specificity 4. Kinetic mechanism 5. Primary structure 6. The active site 7. Mutations in the yeast enzyme 8. Chemical mechanism 9. Binding of coenzymes 10. Hydride transfer

  13. yeast transformation of Mucor circinelloides Tieghe

    African Journals Online (AJOL)

    GRACE

    2006-05-02

    May 2, 2006 ... A nested model analysis of variance of growth data of induced yeast .... Figure 2. Mean biomass and relative growth rates of M. circinelloides cultivated in treatments in ..... Pullman B (ed) Frontiers in Physicochemical Biology.

  14. Genomic Evolution of the Ascomycete Yeasts

    Energy Technology Data Exchange (ETDEWEB)

    Riley, Robert; Haridas, Sajeet; Salamov, Asaf; Boundy-Mills, Kyria; Goker, Markus; Hittinger, Chris; Klenk, Hans-Peter; Lopes, Mariana; Meir-Kolthoff, Jan P.; Rokas, Antonis; Rosa, Carlos; Scheuner, Carmen; Soares, Marco; Stielow, Benjamin; Wisecaver, Jennifer H.; Wolfe, Ken; Blackwell, Meredith; Kurtzman, Cletus; Grigoriev, Igor; Jeffries, Thomas

    2015-03-16

    Yeasts are important for industrial and biotechnological processes and show remarkable metabolic and phylogenetic diversity despite morphological similarities. We have sequenced the genomes of 16 ascomycete yeasts of taxonomic and industrial importance including members of Saccharomycotina and Taphrinomycotina. Phylogenetic analysis of these and previously published yeast genomes helped resolve the placement of species including Saitoella complicata, Babjeviella inositovora, Hyphopichia burtonii, and Metschnikowia bicuspidata. Moreover, we find that alternative nuclear codon usage, where CUG encodes serine instead of leucine, are monophyletic within the Saccharomycotina. Most of the yeasts have compact genomes with a large fraction of single exon genes, and a tendency towards more introns in early-diverging species. Analysis of enzyme phylogeny gives insights into the evolution of metabolic capabilities such as methanol utilization and assimilation of alternative carbon sources.

  15. Yeasts are essential for cocoa bean fermentation.

    Science.gov (United States)

    Ho, Van Thi Thuy; Zhao, Jian; Fleet, Graham

    2014-03-17

    Cocoa beans (Theobroma cacao) are the major raw material for chocolate production and fermentation of the beans is essential for the development of chocolate flavor precursors. In this study, a novel approach was used to determine the role of yeasts in cocoa fermentation and their contribution to chocolate quality. Cocoa bean fermentations were conducted with the addition of 200ppm Natamycin to inhibit the growth of yeasts, and the resultant microbial ecology and metabolism, bean chemistry and chocolate quality were compared with those of normal (control) fermentations. The yeasts Hanseniaspora guilliermondii, Pichia kudriavzevii and Kluyveromyces marxianus, the lactic acid bacteria Lactobacillus plantarum and Lactobacillus fermentum and the acetic acid bacteria Acetobacter pasteurianus and Gluconobacter frateurii were the major species found in the control fermentation. In fermentations with the presence of Natamycin, the same bacterial species grew but yeast growth was inhibited. Physical and chemical analyses showed that beans fermented without yeasts had increased shell content, lower production of ethanol, higher alcohols and esters throughout fermentation and lesser presence of pyrazines in the roasted product. Quality tests revealed that beans fermented without yeasts were purplish-violet in color and not fully brown, and chocolate prepared from these beans tasted more acid and lacked characteristic chocolate flavor. Beans fermented with yeast growth were fully brown in color and gave chocolate with typical characters which were clearly preferred by sensory panels. Our findings demonstrate that yeast growth and activity were essential for cocoa bean fermentation and the development of chocolate characteristics. Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved.

  16. Transcriptional Waves in the Yeast Cell Cycle

    OpenAIRE

    Oliva, Anna; Rosebrock, Adam; Ferrezuelo, Francisco; Pyne, Saumyadipta; Chen, Haiying; Skiena, Steve; Futcher, Bruce; Leatherwood, Janet

    2005-01-01

    Many genes are regulated as an innate part of the eukaryotic cell cycle, and a complex transcriptional network helps enable the cyclic behavior of dividing cells. This transcriptional network has been studied in Saccharomyces cerevisiae (budding yeast) and elsewhere. To provide more perspective on these regulatory mechanisms, we have used microarrays to measure gene expression through the cell cycle of Schizosaccharomyces pombe (fission yeast). The 750 genes with the most significant oscillat...

  17. Determination of tritium in wine yeast samples

    International Nuclear Information System (INIS)

    Cotarlea, Monica-Ionela; Paunescu Niculina; Galeriu, D; Mocanu, N.; Margineanu, R.; Marin, G.

    1998-01-01

    Analytical procedures were developed to determine tritium in wine and wine yeast samples. The content of organic compounds affecting the LSC measurement is reduced by fractioning distillation for wine samples and azeotropic distillation/fractional distillation for wine yeast samples. Finally, the water samples were normally distilled with K MO 4 . The established procedures were successfully applied for wine and wine samples from Murfatlar harvests of the years 1995 and 1996. (authors)

  18. Metabolic Engineering of Oleaginous Yeasts for Fatty Alcohol Production

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wei; Wei, Hui; Knoshaug, Eric; Van Wychen, Stefanie; Xu, Qi; Himmel, Michael E.; Zhang, Min

    2016-04-25

    To develop pathways for advanced biological upgrading of sugars to hydrocarbons, we are seeking biological approaches to produce high carbon efficiency intermediates amenable to separations and catalytic upgrading to hydrocarbon fuels. In this study, we successfully demonstrated fatty alcohol production by oleaginous yeasts Yarrowia lipolytica and Lipomyces starkeyi by expressing a bacteria-derived fatty acyl-CoA reductase (FAR). Moreover, we find higher extracellular distribution of fatty alcohols produced by FAR-expressing L. starkeyi strain as compared to Y. lipolytica strain, which would benefit the downstream product recovery process. In both oleaginous yeasts, long chain length saturated fatty alcohols were predominant, accounting for more than 85% of the total fatty alcohols produced. To the best of our knowledge, this is the first report of fatty alcohol production in L. starkeyi. Taken together, our work demonstrates that in addition to Y. lipolytica, L. starkeyi can also serve as a platform organism for production of fatty acid-derived biofuels and bioproducts via metabolic engineering. We believe strain and process development both will significantly contribute to our goal of producing scalable and cost-effective fatty alcohols from renewable biomass.

  19. Integrative analysis of the mitochondrial proteome in yeast.

    Directory of Open Access Journals (Sweden)

    Holger Prokisch

    2004-06-01

    Full Text Available In this study yeast mitochondria were used as a model system to apply, evaluate, and integrate different genomic approaches to define the proteins of an organelle. Liquid chromatography mass spectrometry applied to purified mitochondria identified 546 proteins. By expression analysis and comparison to other proteome studies, we demonstrate that the proteomic approach identifies primarily highly abundant proteins. By expanding our evaluation to other types of genomic approaches, including systematic deletion phenotype screening, expression profiling, subcellular localization studies, protein interaction analyses, and computational predictions, we show that an integration of approaches moves beyond the limitations of any single approach. We report the success of each approach by benchmarking it against a reference set of known mitochondrial proteins, and predict approximately 700 proteins associated with the mitochondrial organelle from the integration of 22 datasets. We show that a combination of complementary approaches like deletion phenotype screening and mass spectrometry can identify over 75% of the known mitochondrial proteome. These findings have implications for choosing optimal genome-wide approaches for the study of other cellular systems, including organelles and pathways in various species. Furthermore, our systematic identification of genes involved in mitochondrial function and biogenesis in yeast expands the candidate genes available for mapping Mendelian and complex mitochondrial disorders in humans.

  20. Yeast chronological lifespan and proteotoxic stress: is autophagy good or bad?

    Science.gov (United States)

    Sampaio-Marques, Belém; Felgueiras, Carolina; Silva, Alexandra; Rodrigues, Fernando; Ludovico, Paula

    2011-10-01

    Autophagy, a highly conserved proteolytic mechanism of quality control, is essential for the maintenance of metabolic and cellular homoeostasis and for an efficient cellular response to stress. Autophagy declines with aging and is believed to contribute to different aspects of the aging phenotype. The nutrient-sensing pathways PKA (protein kinase A), Sch9 and TOR (target of rapamycin), involved in the regulation of yeast lifespan, also converge on a common targeted process: autophagy. The molecular mechanisms underlying the regulation of autophagy and aging by these signalling pathways in yeast, with special attention to the TOR pathway, are discussed in the present paper. The question of whether or not autophagy could contribute to yeast cell death occurring during CLS (chronological lifespan) is discussed in the light of our findings obtained after autophagy activation promoted by proteotoxic stress. Autophagy progressively increases in cells expressing the aggregation-prone protein α-synuclein and seems to participate in the early cell death and shortening of CLS under these conditions, highlighting that autophagic activity should be maintained below physiological levels to exert its promising anti-aging effects.

  1. The growth of solar radiated yeast

    Energy Technology Data Exchange (ETDEWEB)

    Kraft, T.

    1995-09-01

    This researcher plans to determine if solar radiation affects the growth of yeast. The irradiated yeast was obtained from a sample exposed in space during a Space Shuttle flight of September 9-20, 1994. Further, the control groups were held at: (1) Goddard Space Flight Center (GSFC) in Greenbelt, Maryland; and (2) South Dakota School of Mines and Technology. The procedure used was based on the fact that yeast is most often used in consumable baked goods. Therefore, the yeast was incorporated into a basic Betty Crocker bread recipe. Data was collected by placing measured amounts of dough into sample containers with fifteen minute growth in height measurements collected and recorded. This researcher assumed the viability of yeast to be relative to its ability to produce carbon dioxide gas and cause the dough to rise. As all ingredients and surroundings were equal, this researcher assumed the yeast will produce the only significant difference in data collected. This researcher noted the approximate use date on all sample packages to be prior to arrival and experiment date. All dates equal, it was then assumed each would act in a similar manner of response. This assumption will allow for equally correct data collection.

  2. The growth of solar radiated yeast

    Science.gov (United States)

    Kraft, Tyrone

    1995-01-01

    This researcher plans to determine if solar radiation affects the growth of yeast. The irradiated yeast was obtained from a sample exposed in space during a Space Shuttle flight of September 9-20, 1994. Further, the control groups were held at: (1) Goddard Space Flight Center (GSFC) in Greenbelt, Maryland; and (2) South Dakota School of Mines and Technology. The procedure used was based on the fact that yeast is most often used in consumable baked goods. Therefore, the yeast was incorporated into a basic Betty Crocker bread recipe. Data was collected by placing measured amounts of dough into sample containers with fifteen minute growth in height measurements collected and recorded. This researcher assumed the viability of yeast to be relative to its ability to produce carbon dioxide gas and cause the dough to rise. As all ingredients and surroundings were equal, this researcher assumed the yeast will produce the only significant difference in data collected. This researcher noted the approximate use date on all sample packages to be prior to arrival and experiment date. All dates equal, it was then assumed each would act in a similar manner of response. This assumption will allow for equally correct data collection.

  3. History of genome editing in yeast.

    Science.gov (United States)

    Fraczek, Marcin G; Naseeb, Samina; Delneri, Daniela

    2018-05-01

    For thousands of years humans have used the budding yeast Saccharomyces cerevisiae for the production of bread and alcohol; however, in the last 30-40 years our understanding of the yeast biology has dramatically increased, enabling us to modify its genome. Although S. cerevisiae has been the main focus of many research groups, other non-conventional yeasts have also been studied and exploited for biotechnological purposes. Our experiments and knowledge have evolved from recombination to high-throughput PCR-based transformations to highly accurate CRISPR methods in order to alter yeast traits for either research or industrial purposes. Since the release of the genome sequence of S. cerevisiae in 1996, the precise and targeted genome editing has increased significantly. In this 'Budding topic' we discuss the significant developments of genome editing in yeast, mainly focusing on Cre-loxP mediated recombination, delitto perfetto and CRISPR/Cas. © 2018 The Authors. Yeast published by John Wiley & Sons, Ltd.

  4. Radiodiagnosis of yeast alveolits (a clinicoexperimental study)

    International Nuclear Information System (INIS)

    Amosov, I.S.; Smirnov, V.A.

    1984-01-01

    A clinicoroetgenological study was made of 115 workers engaged in the yeast production for different periods of time. Disorders of the respiration biomechanics were revealed depending on the period of service. These data were obtained as a result of the use of roentgenopneumopolygraphy. An experimental study was conducted to establish the nature of lesions in the bronchopulmonary system in allergic alveolitis. The effect of finely divided yeast dust on the bronchopulmonary system was studied on 132 guinea-pigs usinq microbronchography and morphological examination. As a result of the study it has been established that during the inhalation of yeast dust, notnceable dystrophy of the bronchi develops, the sizes of alveoli enlarge and part of them undergo emphysematous distension with the rupture of the interalveolar septa. In the course of the study, it has been shown that yeast dust is little agreessive, yeast alveolitis develops after many years of work. The clinical symptoms are non-specific and insignificant. X-ray and morphological changes are followed by the physical manifestations of yeast alveolitis

  5. Novel brewing yeast hybrids: creation and application.

    Science.gov (United States)

    Krogerus, Kristoffer; Magalhães, Frederico; Vidgren, Virve; Gibson, Brian

    2017-01-01

    The natural interspecies Saccharomyces cerevisiae × Saccharomyces eubayanus hybrid yeast is responsible for global lager beer production and is one of the most important industrial microorganisms. Its success in the lager brewing environment is due to a combination of traits not commonly found in pure yeast species, principally low-temperature tolerance, and maltotriose utilization. Parental transgression is typical of hybrid organisms and has been exploited previously for, e.g., the production of wine yeast with beneficial properties. The parental strain S. eubayanus has only been discovered recently and newly created lager yeast strains have not yet been applied industrially. A number of reports attest to the feasibility of this approach and artificially created hybrids are likely to have a significant impact on the future of lager brewing. De novo S. cerevisiae × S. eubayanus hybrids outperform their parent strains in a number of respects, including, but not restricted to, fermentation rate, sugar utilization, stress tolerance, and aroma formation. Hybrid genome function and stability, as well as different techniques for generating hybrids and their relative merits are discussed. Hybridization not only offers the possibility of generating novel non-GM brewing yeast strains with unique properties, but is expected to aid in unraveling the complex evolutionary history of industrial lager yeast.

  6. Revaluation of Waste Yeast from Beer Production

    Directory of Open Access Journals (Sweden)

    Nicoleta Suruceanu

    2013-11-01

    Full Text Available Brewing yeast is an important waste product from beer production. The valorification of slurry yeast mainly consists of separation of vitamins and important nitrogen compounds. The hops compounds, one of the most important raw materials in beer technology are removed beforehand valorification. The prenylflavonoids compounds from hops are important bioactive compounds that can be revaluation with proper technology. Revaluation of prenylflavonoids from waste yeast into dietary supplement, identification and quantification of xanthohumol by HPLC method. Waste yeast from brewery pilot plant of USAMV Cluj Napoca it was dried by atomization and the powder was analyzed on xanthohumol content by HPLC method. For quantification a calibration curve it was used. The process of drying by atomisation lead to a powder product. It was used malt dextrin powder for stabilisation. The final product it was encapsulated. The xanthohumol content of powdered yeast it was 1.94 µg/ml. In conclusion the slurry yeast from beer production it is an important source of prenylflavonoids compounds.

  7. Flor Yeast: New Perspectives Beyond Wine Aging

    Science.gov (United States)

    Legras, Jean-Luc; Moreno-Garcia, Jaime; Zara, Severino; Zara, Giacomo; Garcia-Martinez, Teresa; Mauricio, Juan C.; Mannazzu, Ilaria; Coi, Anna L.; Bou Zeidan, Marc; Dequin, Sylvie; Moreno, Juan; Budroni, Marilena

    2016-01-01

    The most important dogma in white-wine production is the preservation of the wine aroma and the limitation of the oxidative action of oxygen. In contrast, the aging of Sherry and Sherry-like wines is an aerobic process that depends on the oxidative activity of flor strains of Saccharomyces cerevisiae. Under depletion of nitrogen and fermentable carbon sources, these yeast produce aggregates of floating cells and form an air–liquid biofilm on the wine surface, which is also known as velum or flor. This behavior is due to genetic and metabolic peculiarities that differentiate flor yeast from other wine yeast. This review will focus first on the most updated data obtained through the analysis of flor yeast with -omic tools. Comparative genomics, proteomics, and metabolomics of flor and wine yeast strains are shedding new light on several features of these special yeast, and in particular, they have revealed the extent of proteome remodeling imposed by the biofilm life-style. Finally, new insights in terms of promotion and inhibition of biofilm formation through small molecules, amino acids, and di/tri-peptides, and novel possibilities for the exploitation of biofilm immobilization within a fungal hyphae framework, will be discussed. PMID:27148192

  8. Measuring strand discontinuity-directed mismatch repair in yeast Saccharomyces cerevisiae by cell-free nuclear extracts.

    Science.gov (United States)

    Yuan, Fenghua; Lai, Fangfang; Gu, Liya; Zhou, Wen; El Hokayem, Jimmy; Zhang, Yanbin

    2009-05-01

    Mismatch repair corrects biosynthetic errors generated during DNA replication, whose deficiency causes a mutator phenotype and directly underlies hereditary non-polyposis colorectal cancer and sporadic cancers. Because of remarkably high conservation of the mismatch repair machinery between the budding yeast (Saccharomyces cerevisiae) and humans, the study of mismatch repair in yeast has provided tremendous insights into the mechanisms of this repair pathway in humans. In addition, yeast cells possess an unbeatable advantage over human cells in terms of the easy genetic manipulation, the availability of whole genome deletion strains, and the relatively low cost for setting up the system. Although many components of eukaryotic mismatch repair have been identified, it remains unclear if additional factors, such as DNA helicase(s) and redundant nuclease(s) besides EXO1, participate in eukaryotic mismatch repair. To facilitate the discovery of novel mismatch repair factors, we developed a straightforward in vitro cell-free repair system. Here, we describe the practical protocols for preparation of yeast cell-free nuclear extracts and DNA mismatch substrates, and the in vitro mismatch repair assay. The validity of the cell-free system was confirmed by the mismatch repair deficient yeast strain (Deltamsh2) and the complementation assay with purified yeast MSH2-MSH6.

  9. Conservation of PHO pathway in ascomycetes and the role of Pho84

    Indian Academy of Sciences (India)

    In budding yeast, Saccharomyces cerevisiae, the phosphate signalling and response pathway, known as PHO pathway, monitors phosphate cytoplasmic levels by controlling genes involved in scavenging, uptake and utilization of phosphate. Recent attempts to understand the phosphate starvation response in other ...

  10. Unexpected expansion of tRNA substrate recognition by the yeast m1G9 methyltransferase Trm10.

    Science.gov (United States)

    Swinehart, William E; Henderson, Jeremy C; Jackman, Jane E

    2013-08-01

    N-1 Methylation of the nearly invariant purine residue found at position 9 of tRNA is a nucleotide modification found in multiple tRNA species throughout Eukarya and Archaea. First discovered in Saccharomyces cerevisiae, the tRNA methyltransferase Trm10 is a highly conserved protein both necessary and sufficient to catalyze all known instances of m1G9 modification in yeast. Although there are 19 unique tRNA species that contain a G at position 9 in yeast, and whose fully modified sequence is known, only 9 of these tRNA species are modified with m1G9 in wild-type cells. The elements that allow Trm10 to distinguish between structurally similar tRNA species are not known, and sequences that are shared between all substrate or all nonsubstrate tRNAs have not been identified. Here, we demonstrate that the in vitro methylation activity of yeast Trm10 is not sufficient to explain the observed pattern of modification in vivo, as additional tRNA species are substrates for Trm10 m1G9 methyltransferase activity. Similarly, overexpression of Trm10 in yeast yields m1G9 containing tRNA species that are ordinarily unmodified in vivo. Thus, yeast Trm10 has a significantly broader tRNA substrate specificity than is suggested by the observed pattern of modification in wild-type yeast. These results may shed light onto the suggested involvement of Trm10 in other pathways in other organisms, particularly in higher eukaryotes that contain up to three different genes with sequence similarity to the single TRM10 gene in yeast, and where these other enzymes have been implicated in pathways beyond tRNA processing.

  11. Spermidine cures yeast of prions

    Directory of Open Access Journals (Sweden)

    Shaun H. Speldewinde

    2015-12-01

    Full Text Available Prions are self-perpetuating amyloid protein aggregates which underlie various neurodegenerative diseases in mammals. The molecular basis underlying their conversion from a normally soluble protein into the prion form remains largely unknown. Studies aimed at uncovering these mechanism(s are therefore essential if we are to develop effective therapeutic strategies to counteract these disease-causing entities. Autophagy is a cellular degradation system which has predominantly been considered as a non-selective bulk degradation process which recycles macromolecules in response to starvation conditions. We now know that autophagy also serves as a protein quality control mechanism which selectively degrades protein aggregates and damaged organelles. These are commonly accumulated in various neurodegenerative disorders including prion diseases. In our recent study [Speldewinde et al. Mol. Biol. Cell. (2015] we used the well-established yeast [PSI+]/Sup35 and [PIN­+]/Rnq1 prion models to show that autophagy prevents sporadic prion formation. Importantly, we found that spermidine, a polyamine that has been used to increase autophagic flux, acts as a protective agent which prevents spontaneous prion formation.

  12. Nutrient sensing and signaling in the yeast Saccharomyces cerevisiae

    Science.gov (United States)

    Conrad, Michaela; Schothorst, Joep; Kankipati, Harish Nag; Van Zeebroeck, Griet; Rubio-Texeira, Marta; Thevelein, Johan M

    2014-01-01

    The yeast Saccharomyces cerevisiae has been a favorite organism for pioneering studies on nutrient-sensing and signaling mechanisms. Many specific nutrient responses have been elucidated in great detail. This has led to important new concepts and insight into nutrient-controlled cellular regulation. Major highlights include the central role of the Snf1 protein kinase in the glucose repression pathway, galactose induction, the discovery of a G-protein-coupled receptor system, and role of Ras in glucose-induced cAMP signaling, the role of the protein synthesis initiation machinery in general control of nitrogen metabolism, the cyclin-controlled protein kinase Pho85 in phosphate regulation, nitrogen catabolite repression and the nitrogen-sensing target of rapamycin pathway, and the discovery of transporter-like proteins acting as nutrient sensors. In addition, a number of cellular targets, like carbohydrate stores, stress tolerance, and ribosomal gene expression, are controlled by the presence of multiple nutrients. The protein kinase A signaling pathway plays a major role in this general nutrient response. It has led to the discovery of nutrient transceptors (transporter receptors) as nutrient sensors. Major shortcomings in our knowledge are the relationship between rapid and steady-state nutrient signaling, the role of metabolic intermediates in intracellular nutrient sensing, and the identity of the nutrient sensors controlling cellular growth. PMID:24483210

  13. Efficient protein production by yeast requires global tuning of metabolism

    DEFF Research Database (Denmark)

    Huang, Mingtao; Bao, Jichen; Hallstrom, Bjorn M.

    2017-01-01

    The biotech industry relies on cell factories for production of pharmaceutical proteins, of which several are among the top-selling medicines. There is, therefore, considerable interest in improving the efficiency of protein production by cell factories. Protein secretion involves numerous...... intracellular processes with many underlying mechanisms still remaining unclear. Here, we use RNA-seq to study the genome-wide transcriptional response to protein secretion in mutant yeast strains. We find that many cellular processes have to be attuned to support efficient protein secretion. In particular...... that by tuning metabolism cells are able to efficiently secrete recombinant proteins. Our findings provide increased understanding of which cellular regulations and pathways are associated with efficient protein secretion....

  14. Ddb1 controls genome stability and meiosis in fission yeast

    DEFF Research Database (Denmark)

    Holmberg, Christian Henrik; Fleck, Oliver; Hansen, H. A.

    2005-01-01

    The human UV-damaged DNA-binding protein Ddb1 associates with cullin 4 ubiquitin ligases implicated in nucleotide excision repair (NER). These complexes also contain the signalosome (CSN), but NER-relevant ubiquitination targets have not yet been identified. We report that fission yeast Ddb1......, Cullin 4 (Pcu4), and CSN subunits Csn1 and Csn2 are required for degradation of the ribonucleotide reductase (RNR) inhibitor protein Spd1. Ddb1-deficient cells have >20-fold increased spontaneous mutation rate. This is partly dependent on the error-prone translesion DNA polymerases. Spd1 deletion...... substantially reduced the mutation rate, suggesting that insufficient RNR activity accounts for ~50% of observed mutations. Epistasis analysis indicated that Ddb1 contributed to mutation avoidance and tolerance to DNA damage in a pathway distinct from NER. Finally, we show that Ddb1/Csn1/Cullin 4-mediated Spd1...

  15. Improving yeast strains using recyclable integration cassettes, for the production of plant terpenoids

    Directory of Open Access Journals (Sweden)

    Johnson Christopher B

    2011-01-01

    Full Text Available Abstract Background Terpenoids constitute a large family of natural products, attracting commercial interest for a variety of uses as flavours, fragrances, drugs and alternative fuels. Saccharomyces cerevisiae offers a versatile cell factory, as the precursors of terpenoid biosynthesis are naturally synthesized by the sterol biosynthetic pathway. Results S. cerevisiae wild type yeast cells, selected for their capacity to produce high sterol levels were targeted for improvement aiming to increase production. Recyclable integration cassettes were developed which enable the unlimited sequential integration of desirable genetic elements (promoters, genes, termination sequence at any desired locus in the yeast genome. The approach was applied on the yeast sterol biosynthetic pathway genes HMG2, ERG20 and IDI1 resulting in several-fold increase in plant monoterpene and sesquiterpene production. The improved strains were robust and could sustain high terpenoid production levels for an extended period. Simultaneous plasmid-driven co-expression of IDI1 and the HMG2 (K6R variant, in the improved strain background, maximized monoterpene production levels. Expression of two terpene synthase enzymes from the sage species Salvia fruticosa and S. pomifera (SfCinS1, SpP330 in the modified yeast cells identified a range of terpenoids which are also present in the plant essential oils. Co-expression of the putative interacting protein HSP90 with cineole synthase 1 (SfCinS1 also improved production levels, pointing to an additional means to improve production. Conclusions Using the developed molecular tools, new yeast strains were generated with increased capacity to produce plant terpenoids. The approach taken and the durability of the strains allow successive rounds of improvement to maximize yields.

  16. A Comparison of Two Yeast MnSODs: Mitochondrial Saccharomyces cerevisiae versus Cytosolic Candida albicans

    International Nuclear Information System (INIS)

    Sheng, Y.; Cabelli, D.; Stich, T.A.; Barnese, K.; Gralla, E.B.; Cascio, D.; Britt, R.D.; Valentine, J.S.

    2011-01-01

    Human MnSOD is significantly more product-inhibited than bacterial MnSODs at high concentrations of superoxide (O 2 - ). This behavior limits the amount of H 2 O 2 produced at high [O 2 - ]; its desirability can be explained by the multiple roles of H 2 O 2 in mammalian cells, particularly its role in signaling. To investigate the mechanism of product inhibition in MnSOD, two yeast MnSODs, one from Saccharomyces cerevisiae mitochondria (ScMnSOD) and the other from Candida albicans cytosol (CaMnSODc), were isolated and characterized. ScMnSOD and CaMnSODc are similar in catalytic kinetics, spectroscopy, and redox chemistry, and they both rest predominantly in the reduced state (unlike most other MnSODs). At high [O 2 - ], the dismutation efficiencies of the yeast MnSODs surpass those of human and bacterial MnSODs, due to very low level of product inhibition. Optical and parallel-mode electron paramagnetic resonance (EPR) spectra suggest the presence of two Mn 3+ species in yeast Mn 3+ SODs, including the well-characterized 5-coordinate Mn 3+ species and a 6-coordinate L-Mn 3+ species with hydroxide as the putative sixth ligand (L). The first and second coordination spheres of ScMnSOD are more similar to bacterial than to human MnSOD. Gln154, an H-bond donor to the Mn-coordinated solvent molecule, is slightly further away from Mn in yeast MnSODs, which may result in their unusual resting state. Mechanistically, the high efficiency of yeast MnSODs could be ascribed to putative translocation of an outer-sphere solvent molecule, which could destabilize the inhibited complex and enhance proton transfer from protein to peroxide. Our studies on yeast MnSODs indicate the unique nature of human MnSOD in that it predominantly undergoes the inhibited pathway at high [O 2 - ].

  17. Mapping of sulfur metabolic pathway by LC Orbitrap mass spectrometry

    International Nuclear Information System (INIS)

    Rao Yulan; McCooeye, Margaret; Mester, Zoltán

    2012-01-01

    Highlights: ► LCMS method for the determination of free, oxidized and protein bound thiols in yeast was developed. ► In freshly harvested yeast, most of the thiols were in the reduced forms. ► The stress response of yeast to H 2 O 2 , Cd and As was studied via changes in the thiol profiles. - Abstract: For the first time a liquid chromatography method with high resolution mass spectrometric detection has been developed for the simultaneous determination all key metabolites of the sulfur pathway in yeast, including all thiolic (cysteine (Cys), homocysteine (HCys), glutathione (GSH), cysteinyl-glycine (Cys-Gly), γ-glutamyl-cysteine (Glu-Cys)) and non-thiolic compounds (methionine (Met), s-adenosyl-methionine (AdoMet), s-adenosyl-homocysteine (AdoHcy), and cystathionine (Cysta)). The developed assay also permits the speciation and selective determination of reduced, oxidized and protein bound fractions of all of the five thiols. Iodoacetic acid (IAA) was chosen as the derivatizing reagent. Thiols were extracted from sub-mg quantities of yeast using hot 75% ethanol. The detection limits were in the range of 1–12 nmol L −1 for standard solution (high femotomole, absolute), except AdoMet (116 nmol L −1 ), which was unstable. In freshly harvested yeast, most of the thiols were in the reduced forms and low levels of protein-bound GSH and Glu-Cys were found. In a selenium enriched yeast, the thiols were mainly in the oxidized forms, and a significant amount of protein-bound Cys, HCys, GSH, Cys-Gly and Glu-Cys were found. The method was also applied to the metabolic study of the adaptive response of Saccharomyces cerevisiae to hydrogen peroxide, cadmium, and arsenite, and the change in concentration of thiols in the sulfur pathway was monitored over a period of 4 h.

  18. Mapping of sulfur metabolic pathway by LC Orbitrap mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Rao Yulan [Institute for National Measurement Standard, National Research Council Canada, Ottawa, Ontario K1A 0R6 (Canada); Department of Forensic Medicine, Shanghai Medical College, Fudan University, Shanghai 200032 (China); McCooeye, Margaret [Institute for National Measurement Standard, National Research Council Canada, Ottawa, Ontario K1A 0R6 (Canada); Mester, Zoltan, E-mail: zoltan.mester@nrc.ca [Institute for National Measurement Standard, National Research Council Canada, Ottawa, Ontario K1A 0R6 (Canada)

    2012-04-06

    Highlights: Black-Right-Pointing-Pointer LCMS method for the determination of free, oxidized and protein bound thiols in yeast was developed. Black-Right-Pointing-Pointer In freshly harvested yeast, most of the thiols were in the reduced forms. Black-Right-Pointing-Pointer The stress response of yeast to H{sub 2}O{sub 2}, Cd and As was studied via changes in the thiol profiles. - Abstract: For the first time a liquid chromatography method with high resolution mass spectrometric detection has been developed for the simultaneous determination all key metabolites of the sulfur pathway in yeast, including all thiolic (cysteine (Cys), homocysteine (HCys), glutathione (GSH), cysteinyl-glycine (Cys-Gly), {gamma}-glutamyl-cysteine (Glu-Cys)) and non-thiolic compounds (methionine (Met), s-adenosyl-methionine (AdoMet), s-adenosyl-homocysteine (AdoHcy), and cystathionine (Cysta)). The developed assay also permits the speciation and selective determination of reduced, oxidized and protein bound fractions of all of the five thiols. Iodoacetic acid (IAA) was chosen as the derivatizing reagent. Thiols were extracted from sub-mg quantities of yeast using hot 75% ethanol. The detection limits were in the range of 1-12 nmol L{sup -1} for standard solution (high femotomole, absolute), except AdoMet (116 nmol L{sup -1}), which was unstable. In freshly harvested yeast, most of the thiols were in the reduced forms and low levels of protein-bound GSH and Glu-Cys were found. In a selenium enriched yeast, the thiols were mainly in the oxidized forms, and a significant amount of protein-bound Cys, HCys, GSH, Cys-Gly and Glu-Cys were found. The method was also applied to the metabolic study of the adaptive response of Saccharomyces cerevisiae to hydrogen peroxide, cadmium, and arsenite, and the change in concentration of thiols in the sulfur pathway was monitored over a period of 4 h.

  19. Metabolic engineering of oleaginous yeast Yarrowia lipolytica for limonene overproduction.

    Science.gov (United States)

    Cao, Xuan; Lv, Yu-Bei; Chen, Jun; Imanaka, Tadayuki; Wei, Liu-Jing; Hua, Qiang

    2016-01-01

    Limonene, a monocyclic monoterpene, is known for its using as an important precursor of many flavoring, pharmaceutical, and biodiesel products. Currently, d-limonene has been produced via fractionation from essential oils or as a byproduct of orange juice production, however, considering the increasing need for limonene and a certain amount of pesticides may exist in the limonene obtained from the citrus industry, some other methods should be explored to produce limonene. To construct the limonene synthetic pathway in Yarrowia lipolytica , two genes encoding neryl diphosphate synthase 1 (NDPS1) and limonene synthase (LS) were codon-optimized and heterologously expressed in Y. lipolytica . Furthermore, to maximize limonene production, several genes involved in the MVA pathway were overexpressed, either in different copies of the same gene or in combination. Finally with the optimized pyruvic acid and dodecane concentration in flask culture, a maximum limonene titer and content of 23.56 mg/L and 1.36 mg/g DCW were achieved in the final engineered strain Po1f-LN-051, showing approximately 226-fold increase compared with the initial yield 0.006 mg/g DCW. This is the first report on limonene biosynthesis in oleaginous yeast Y. lipolytica by heterologous expression of codon-optimized tLS and tNDPS1 genes. To our knowledge, the limonene production 23.56 mg/L, is the highest limonene production level reported in yeast. In short, we demonstrate that Y. lipolytica provides a compelling platform for the overproduction of limonene derivatives, and even other monoterpenes.

  20. Application of synthetic biology for production of chemicals in yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    Li, Mingji; Borodina, Irina

    2015-02-01

    Synthetic biology and metabolic engineering enable generation of novel cell factories that efficiently convert renewable feedstocks into biofuels, bulk, and fine chemicals, thus creating the basis for biosustainable economy independent on fossil resources. While over a hundred proof-of-concept chemicals have been made in yeast, only a very small fraction of those has reached commercial-scale production so far. The limiting factor is the high research cost associated with the development of a robust cell factory that can produce the desired chemical at high titer, rate, and yield. Synthetic biology has the potential to bring down this cost by improving our ability to predictably engineer biological systems. This review highlights synthetic biology applications for design, assembly, and optimization of non-native biochemical pathways in baker's yeast Saccharomyces cerevisiae We describe computational tools for the prediction of biochemical pathways, molecular biology methods for assembly of DNA parts into pathways, and for introducing the pathways into the host, and finally approaches for optimizing performance of the introduced pathways. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permission@oup.com.

  1. NetPhosYeast: prediction of protein phosphorylation sites in yeast

    DEFF Research Database (Denmark)

    Ingrell, C.R.; Miller, Martin Lee; Jensen, O.N.

    2007-01-01

    sites compared to those in humans, suggesting the need for an yeast-specific phosphorylation site predictor. NetPhosYeast achieves a correlation coefficient close to 0.75 with a sensitivity of 0.84 and specificity of 0.90 and outperforms existing predictors in the identification of phosphorylation sites...

  2. Differences between flocculating yeast and regular industrial yeast in transcription and metabolite profiling during ethanol fermentation

    Directory of Open Access Journals (Sweden)

    Lili Li

    2017-03-01

    Full Text Available Objectives: To improve ethanolic fermentation performance of self-flocculating yeast, difference between a flocculating yeast strain and a regular industrial yeast strain was analyzed by transcriptional and metabolic approaches. Results: The number of down-regulated (industrial yeast YIC10 vs. flocculating yeast GIM2.71 and up-regulated genes were 4503 and 228, respectively. It is the economic regulation for YIC10 that non-essential genes were down-regulated, and cells put more “energy” into growth and ethanol production. Hexose transport and phosphorylation were not the limiting-steps in ethanol fermentation for GIM2.71 compared to YIC10, whereas the reaction of 1,3-disphosphoglycerate to 3-phosphoglycerate, the decarboxylation of pyruvate to acetaldehyde and its subsequent reduction to ethanol were the most limiting steps. GIM2.71 had stronger stress response than non-flocculating yeast and much more carbohydrate was distributed to other bypass, such as glycerol, acetate and trehalose synthesis. Conclusions: Differences between flocculating yeast and regular industrial yeast in transcription and metabolite profiling will provide clues for improving the fermentation performance of GIM2.71.

  3. Yeast Interacting Proteins Database: YFR015C, YFR015C [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available yeast homolog; expression induced by glucose limitation, nitrogen starvation, environmental stress, and entr...ression induced by glucose limitation, nitrogen starvation, environmental stress, and entry into stationary ...tion, nitrogen starvation, environmental stress, and entry into stationary phase Rows with this bait as bait..., the more highly expressed yeast homolog; expression induced by glucose limitation, nitrogen starvation, environmental

  4. Increasing the yeast yield in alcohol fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Pelc, A; Vamos, E; Varga, L; Gavalya, S; Dolanszky, F

    1964-02-01

    The yeast and ethanol yields (the latter being based on the substrate) are enhanced by adding the substrate (molasses) gradually to the suspension of inoculating yeast during the main fermentation period, passing air through the mash, ceasing both substrate addition and aeration at the end of the main period, and allowing the process to come to an end. This way 12 to 14 kg yeast (dry weight)/100 l ethanol could be obtained within 16 to 24 hours and the yeast obtained could be used as the inoculum for the next charge. For example: 11 to 16 kg yeast (or 18 to 25 l yeast suspension from the preceding charge, containing 18 to 20% dry matter) is kept in 30 to 35 l H/sub 2/SO/sub 4/ (0.74 g/100 ml) for 1 hour, diluted with H/sub 2/O and 30 kg sterile molasses to 300 l, kept at 30 to 32/sup 0/ with mild aeration for 2 hours, 1900 l 30/sup 0/ H/sub 2/O added, then 1 m/sup 3/ air/m/sup 2//hour is passed through the mixture, with the addition of 270 kg sterile molasses, and a solution of 8 kg superphosphate and 5 kg (NH/sub 4/)/sub 2/SO/sub 4/ in 100 l H/sub 2/O, the latter being added in 5 portions over 2 hours. Molasses (600 kg) is added during the main period, maintaining the pH at 5 (H/sub 2/SO/sub 4/), and the temperature at 30/sup 0/, then aeration is ceased and the mixture kept until fermentation proceeds. The 3000 l medium contains 9.6% ethanol and 1.38% yeast, respectively.

  5. Schizosaccharomyces japonicus: the fission yeast is a fusion of yeast and hyphae.

    Science.gov (United States)

    Niki, Hironori

    2014-03-01

    The clade of Schizosaccharomyces includes 4 species: S. pombe, S. octosporus, S. cryophilus, and S. japonicus. Although all 4 species exhibit unicellular growth with a binary fission mode of cell division, S. japonicus alone is dimorphic yeast, which can transit from unicellular yeast to long filamentous hyphae. Recently it was found that the hyphal cells response to light and then synchronously activate cytokinesis of hyphae. In addition to hyphal growth, S. japonicas has many properties that aren't shared with other fission yeast. Mitosis of S. japonicas is referred to as semi-open mitosis because dynamics of nuclear membrane is an intermediate mode between open mitosis and closed mitosis. Novel genetic tools and the whole genomic sequencing of S. japonicas now provide us with an opportunity for revealing unique characters of the dimorphic yeast. © 2013 The Author. Yeast Published by John Wiley & Sons Ltd.

  6. Terroir of yeasts? – Application of FTIR spectroscopy and molecular methods for strain typing of yeasts

    Directory of Open Access Journals (Sweden)

    Gerhards Daniel

    2015-01-01

    Full Text Available The site specific influence on wine (Terroir is an often by wine producers, consumers and scientists discussed topic in the world of wine. A study on grapes and (spontaneous fermentations from six different vineyards was done to investigate the biodiversity of yeasts and to answer the question if there is a terroir of yeast and how it could be influenced. Randomly isolated yeasts were identified by FTIR-spectroscopy and molecular methods on species and strain level. Vineyard specific yeast floras would be observed but they are not such important as expected. Only a few overlapping strain patterns would be identified during both vintages. The yeast flora of the winery had a huge impact on the spontaneous fermentations, but is not really constant and influenced by different factors from outside.

  7. Protein functional analysis data in support of comparative proteomics of the pathogenic black yeast Exophiala dermatitidis under different temperature conditions

    Directory of Open Access Journals (Sweden)

    Donatella Tesei

    2015-12-01

    Full Text Available In the current study a comparative proteomic approach was used to investigate the response of the human pathogen black yeast Exophiala dermatitidis toward temperature treatment. Protein functional analysis – based on cellular process GO terms – was performed on the 32 temperature-responsive identified proteins. The bioinformatics analyses and data presented here provided novel insights into the cellular pathways at the base of the fungus temperature tolerance. A detailed analysis and interpretation of the data can be found in “Proteome of tolerance fine-tuning in the human pathogen black yeast Exophiala dermatitidis” by Tesei et al. (2015 [1].

  8. Present status of DNA repair mechanisms in uv irradiated yeast taken as a model eukaryotic system

    International Nuclear Information System (INIS)

    Moustacchi, E.; Waters, R.; Heude, M.; Chanet, R.

    1975-01-01

    The repair mechanisms of altered DNA are generally less well understood for eukaryotes than they are for prokaryotes and bacteriophages. For mammalian cell lines cultured in vitro the specific labelling of DNA has allowed the biochemical analysis of some of the steps of the repair processes whereas the determination of their genetic controls is, with a few exceptions, obviously difficult. On the other hand, with fungi and more specifically with yeast taken as a model unicellular eukaryotic system, the genetic approach has been extensively explored: radiosensitive mutants are readily detected and genetically analyzed, double and multiple mutants can be constructed and from their responses to irradiation the number of repair pathways involved can be suggested. The lack of thymidine kinase in these organisms has hampered for a certain time the biochemical analysis of repair. However, the recent isolation of yeast strains capable of taking up and incorporating thymidine 5'-monophosphate into their DNA opens new possibilities for the future. In spite of this difficulty, attempts to measure the induction and removal of uv-induced pyrimidine dimers were performed by several groups during the last three years. The two main repair pathways described for E. coli, i.e., the excision-resynthesis and post-replicative recombinational repair pathways, do exist in yeast. The existence of the former pathway is supported not only by indirect evidence but also by biochemical analysis. The rad 1 and rad 2 mutants for instance have been shown to be blocked in the excision of uv-induced pyrimidine dimers. Other loci are epistatic to rad 1 and rad 2 (rad 3 , rad 4 ) and are likely to act on this excision pathway. The genetic control of the mitochondrial response to a uv treatment involves nuclear genes and mitochondrial determinants

  9. Protein patterns of yeast during sporulation

    International Nuclear Information System (INIS)

    Litske Petersen, J.G.; Kielland-Brandt, M.C.; Nilsson-Tillgren, T.

    1979-01-01

    High resolution two-dimensional gel electrophoresis was used to study protein synthesis during synchronous meiosis and ascospore formation of Saccharomyces cerevisiae. The stained protein patterns of samples harvested at any stage between meiotic prophase and the four-spore stage in two sporulating strains showed the same approximately 250 polypeptides. Of these only a few seemed to increase or decrease in concentration during sporulation. The characteristic pattern of sporulating yeast was identical to the pattern of glucose-grown staitonary yeast cells adapted to respiration. The latter type of cells readily initiates meiosis when transferred to sporulation medium. This pattern differed from the protein patterns of exponentially growing cells in glucose or acetate presporulation medium. Five major proteins in stationary and sporulating yeast cells were not detected in either type of exponential culture. Two-dimensional autoradiograms of [ 35 S]methionine-labelled yeast proteins revealed that some proteins were preferentially labelled during sporulation, while other proteins were labelled at later stages. These patterns differed from the auroradiograms of exponentially growing yeast cells in glucose presporulation medium in a number of spots. No differences were observed when stained gels or autoradiograms of sporulating cultures and non-sporulating strains in sporulation medium were compared. (author)

  10. Bioethanol a Microbial Biofuel Metabolite; New Insights of Yeasts Metabolic Engineering

    Directory of Open Access Journals (Sweden)

    Khaled A. Selim

    2018-03-01

    Full Text Available Scarcity of the non-renewable energy sources, global warming, environmental pollution, and raising the cost of petroleum are the motive for the development of renewable, eco-friendly fuels production with low costs. Bioethanol production is one of the promising materials that can subrogate the petroleum oil, and it is considered recently as a clean liquid fuel or a neutral carbon. Diverse microorganisms such as yeasts and bacteria are able to produce bioethanol on a large scale, which can satisfy our daily needs with cheap and applicable methods. Saccharomyces cerevisiae and Pichia stipitis are two of the pioneer yeasts in ethanol production due to their abilities to produce a high amount of ethanol. The recent focus is directed towards lignocellulosic biomass that contains 30–50% cellulose and 20–40% hemicellulose, and can be transformed into glucose and fundamentally xylose after enzymatic hydrolysis. For this purpose, a number of various approaches have been used to engineer different pathways for improving the bioethanol production with simultaneous fermentation of pentose and hexoses sugars in the yeasts. These approaches include metabolic and flux analysis, modeling and expression analysis, followed by targeted deletions or the overexpression of key genes. In this review, we highlight and discuss the current status of yeasts genetic engineering for enhancing bioethanol production, and the conditions that influence bioethanol production.

  11. Functional toxicogenomic profiling expands insight into modulators of formaldehyde toxicity in yeast

    Directory of Open Access Journals (Sweden)

    Matthew North

    2016-11-01

    Full Text Available Formaldehyde (FA is a commercially important chemical with numerous and diverse uses. Accordingly, occupational and environmental exposure to FA is prevalent worldwide. Various adverse effects, including nasopharyngeal, sinonasal, and lymphohematopoietic cancers, have been linked to FA exposure, prompting designation of FA as a human carcinogen by U.S. and international scientific entities. Although the mechanism(s of FA toxicity have been well studied, additional insight is needed in regard to the genetic requirements for FA tolerance. In this study, a functional toxicogenomics approach was utilized in the model eukaryotic yeast Saccharomyces cerevisiae to identify genes and cellular processes modulating the cellular toxicity of FA. Our results demonstrate mutant strains deficient in multiple DNA repair pathways–including homologous recombination, single strand annealing, and postreplication repair–were sensitive to FA, indicating FA may cause various forms of DNA damage in yeast. The SKI complex and its associated factors, which regulate mRNA degradation by the exosome, were also required for FA tolerance, suggesting FA may have unappreciated effects on RNA stability. Furthermore, various strains involved in osmoregulation and stress response were sensitive to FA. Together, our results are generally consistent with FA-mediated damage to both DNA and RNA. Considering DNA repair and RNA degradation pathways are evolutionarily conserved from yeast to humans, mechanisms of FA toxicity identified in yeast may be relevant to human disease and genetic susceptibility.

  12. Pyruvate Decarboxylase Activity Assay in situ of Different Industrial Yeast Strains

    Directory of Open Access Journals (Sweden)

    Dorota Kręgiel

    2009-01-01

    Full Text Available Cytoplasmic pyruvate decarboxylase (PDC, EC 4.1.1.1 is one of the key enzymes of yeast fermentative metabolism. PDC is the first enzyme which, under anaerobic conditions, leads to decarboxylation of pyruvate with acetaldehyde as the end product. The aim of this study is to develop a suitable method for PDC activity assay in situ for different industrial yeast strains. Saccharomyces sp. and Debaryomyces sp. yeast strains grew in fermentative medium with 12 % of glucose. Enzymatic assay was conducted in cell suspension treated with digitonin as permeabilisation agent, and with sodium pyruvate as a substrate, at temperature of 30 °C. Metabolites of PDC pathway were detected using gas chromatographic (GC technique. Various parameters like type and molar concentration of the substrate, minimal effective mass fraction of digitonin, cell concentration, reaction time and effect of pyrazole (alcohol dehydrogenase inhibitor were monitored to optimize PDC enzymatic assay in situ. In the concentration range of yeast cells from 1⋅10^7 to 1⋅10^8 per mL, linear correlation between the produced acetaldehyde and cell density was noticed. Only pyruvate was the specific substrate for pyruvate decarboxylase. In the presence of 0.05 M sodium pyruvate and 0.05 % digitonin, the enzymatic reaction was linear up to 20 min of the assay. During incubation, there was no formation of ethanol and, therefore, pyrazole was not necessary for the assay.

  13. A soluble diacylglycerol acyltransferase is involved in triacylglycerol biosynthesis in the oleaginous yeast Rhodotorula glutinis.

    Science.gov (United States)

    Rani, Sapa Hima; Saha, Saikat; Rajasekharan, Ram

    2013-01-01

    The biosynthesis of triacylglycerol (TAG) occurs in the microsomal membranes of eukaryotes. Here, we report the identification and functional characterization of diacylglycerol acyltransferase (DGAT), a member of the 10 S cytosolic TAG biosynthetic complex (TBC) in Rhodotorula glutinis. Both a full-length and an N-terminally truncated cDNA clone of a single gene were isolated from R. glutinis. The DGAT activity of the protein encoded by RgDGAT was confirmed in vivo by the heterologous expression of cDNA in a Saccharomyces cerevisiae quadruple mutant (H1246) that is defective in TAG synthesis. RgDGAT overexpression in yeast was found to be capable of acylating diacylglycerol (DAG) in an acyl-CoA-dependent manner. Quadruple mutant yeast cells exhibit growth defects in the presence of oleic acid, but wild-type yeast cells do not. In an in vivo fatty acid supplementation experiment, RgDGAT expression rescued quadruple mutant growth in an oleate-containing medium. We describe a soluble acyl-CoA-dependent DAG acyltransferase from R. glutinis that belongs to the DGAT3 class of enzymes. The study highlights the importance of an alternative TAG biosynthetic pathway in oleaginous yeasts.

  14. Expression of death receptor 4 induces caspase-independent cell death in MMS-treated yeast.

    Science.gov (United States)

    Kang, Mi-Sun; Lee, Sung-Keun; Park, Chang-Shin; Kang, Ju-Hee; Bae, Sung-Ho; Yu, Sung-Lim

    2008-11-14

    DR4, a tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor, is a key element in the extrinsic pathway of TRAIL/TRAIL receptor-related apoptosis that exerts a preferential toxic effect against tumor cells. However, TRAIL and DR4 are expressed in various normal cells, and recent studies indicate that DR4 has a number of non-apoptotic functions. In this study, we evaluated the effects of human DR4 expression in yeast to determine the function of DR4 in normal cells. The expression of DR4 in yeast caused G1 arrest, which resulted in transient growth inhibition. Moreover, treatment of DR4-expressing yeast with a DNA damaging agent, MMS, elicited drastic, and sustained cell growth inhibition accompanied with massive apoptotic cell death. Further analysis revealed that cell death in the presence of DNA damage and DR4 expression was not dependent on the yeast caspase, YCA1. Taken together, these results indicate that DR4 triggers caspase-independent programmed cell death during the response of normal cells to DNA damage.

  15. Differential Proteome Analysis of a Flor Yeast Strain under Biofilm Formation.

    Science.gov (United States)

    Moreno-García, Jaime; Mauricio, Juan Carlos; Moreno, Juan; García-Martínez, Teresa

    2017-03-28

    Several Saccharomyces cerevisiae strains (flor yeasts) form a biofilm (flor velum) on the surface of Sherry wines after fermentation, when glucose is depleted. This flor velum is fundamental to biological aging of these particular wines. In this study, we identify abundant proteins in the formation of the biofilm of an industrial flor yeast strain. A database search to enrich flor yeast "biological process" and "cellular component" according to Gene Ontology Terminology (GO Terms) and, "pathways" was carried out. The most abundant proteins detected were largely involved in respiration, translation, stress damage prevention and repair, amino acid metabolism (glycine, isoleucine, leucine and arginine), glycolysis/gluconeogenesis and biosynthesis of vitamin B9 (folate). These proteins were located in cellular components as in the peroxisome, mitochondria, vacuole, cell wall and extracellular region; being these two last directly related with the flor formation. Proteins like Bgl2p, Gcv3p, Hyp2p, Mdh1p, Suc2p and Ygp1p were quantified in very high levels. This study reveals some expected processes and provides new and important information for the design of conditions and genetic constructions of flor yeasts for improving the cellular survival and, thus, to optimize biological aging of Sherry wine production.

  16. Yeast genetics. A manual of methods

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, J.F.T.; Spencer, D.M.; Bruce, I.J.

    1989-01-01

    This is a bench-top manual of methods needed both for classical genetics as related to yeasts, such as mating, sporulation, isolation of hybrids, microdissection of asci for the isolation of single-spore clones, as well as for mapping of genes and the construction of new strains by protoplast fusion. Special emphasis is on mutations in general, and on methods of isolating a number of important classes of mutants in particular. Basic techniques for the separation of chromosomes by electrophoresis, such as OFAGE, FIGE, and CHEF, are discussed, with detailed protocols for the first two. Furthermore, new methods, e.g. for the isolation of high molecular weight DNA from yeast, isolation of RNA, and techniques for transformation of yeasts, are also described in detail. (orig.) With 10 figs.

  17. Modeling diauxic glycolytic oscillations in yeast

    DEFF Research Database (Denmark)

    Hald, Bjørn Olav; Sørensen, Preben Graae

    2010-01-01

    for investigations of central metabolism dynamics of yeast cells. We have previously proposed a model for the open system comprised of the primary fermentative reactions in yeast that quantitatively describes the oscillatory dynamics. However, this model fails to describe the transient behavior of metabolic......Glycolytic oscillations in a stirred suspension of starved yeast cells is an excellent model system for studying the dynamics of metabolic switching in living systems. In an open-flow system the oscillations can be maintained indefinitely at a constant operating point where they can....... Experimental and computational results strongly suggest that regulation of acetaldehyde explains the observed behavior. We have extended the original model with regulation of pyruvate decarboxylase, a reversible alcohol dehydrogenase, and drainage of pyruvate. Using the method of time rescaling in the extended...

  18. [Urinary infection by Saccharomyces cerevisiae: Emerging yeast?].

    Science.gov (United States)

    Elkhihal, B; Elhalimi, M; Ghfir, B; Mostachi, A; Lyagoubi, M; Aoufi, S

    2015-12-01

    Saccharomyces cerevisiae is a commensal yeast of the digestive, respiratory and genito-urinary tract. It is widely used as a probiotic for the treatment of post-antibiotic diarrhea. It most often occurs in immunocompromised patients frequently causing fungemia. We report the case of an adult diabetic patient who had a urinary tract infection due to S. cerevisiae. The disease started with urination associated with urinary frequency burns without fever. The diagnosis was established by the presence of yeasts on direct examination and positivity of culture on Sabouraud-chloramphenicol three times. The auxanogramme gallery (Auxacolor BioRad(®)) allowed the identification of S. cerevisiae. The patient was put on fluconazole with good outcome. This observation points out that this is an opportunistic yeast in immunocompromised patients. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  19. Structural Studies of the Yeast Mitochondrial Degradosome

    DEFF Research Database (Denmark)

    Feddersen, Ane; Jonstrup, Anette Thyssen; Brodersen, Ditlev Egeskov

    The yeast mitochondrial degradosome/exosome (mtExo) is responsible for most RNA turnover in mitochondria and has been proposed to form a central part of a mitochondrial RNA surveillance system responsible for degradation of aberrant and unprocessed RNA ([1], [2]). In contrast to the cytoplasmic...... and nuclear exosome complexes, which consist of 10-12 different nuclease subunits, the mitochondrial degradosome is composed of only two large subunits - an RNase (Dss1p) and a helicase (Suv3p), belonging the Ski2 class of DExH box RNA helicases. Both subunits are encoded on the yeast nuclear genome...... and and Suv3p from the fission yeast, Schizosaccharomyces pombe, have been cloned for heterologous expression in E. coli. Of the two, we have succeeded in purifying the 73kDa Suv3p by Ni2+-affinity chromatography followed by cleavage of the N-terminal His-tag, cation exchange, and gel filtration. Crystals...

  20. Flux control through protein phosphorylation in yeast

    DEFF Research Database (Denmark)

    Chen, Yu; Nielsen, Jens

    2016-01-01

    Protein phosphorylation is one of the most important mechanisms regulating metabolism as it can directly modify metabolic enzymes by the addition of phosphate groups. Attributed to such a rapid and reversible mechanism, cells can adjust metabolism rapidly in response to temporal changes. The yeast...... as well as identify mechanisms underlying human metabolic diseases. Here we collect functional phosphorylation events of 41 enzymes involved in yeast metabolism and demonstrate functional mechanisms and the application of this information in metabolic engineering. From a systems biology perspective, we...... describe the development of phosphoproteomics in yeast as well as approaches to analysing the phosphoproteomics data. Finally, we focus on integrated analyses with other omics data sets and genome-scale metabolic models. Despite the advances, future studies improving both experimental technologies...

  1. Biofuels. Altered sterol composition renders yeast thermotolerant

    DEFF Research Database (Denmark)

    Caspeta, Luis; Chen, Yun; Ghiaci, Payam

    2014-01-01

    adaptive laboratory evolution to select yeast strains with improved growth and ethanol production at ≥40°C. Sequencing of the whole genome, genome-wide gene expression, and metabolic-flux analyses revealed a change in sterol composition, from ergosterol to fecosterol, caused by mutations in the C-5 sterol......Ethanol production for use as a biofuel is mainly achieved through simultaneous saccharification and fermentation by yeast. Operating at ≥40°C would be beneficial in terms of increasing efficiency of the process and reducing costs, but yeast does not grow efficiently at those temperatures. We used...... desaturase gene, and increased expression of genes involved in sterol biosynthesis. Additionally, large chromosome III rearrangements and mutations in genes associated with DNA damage and respiration were found, but contributed less to the thermotolerant phenotype....

  2. Probiotic Properties of Non-Saccharomyces Yeasts

    DEFF Research Database (Denmark)

    Smith, Ida Mosbech

    to harmless luminal substances is a key feature of the intestinal immune system. In this context, dendritic cells (DCs) present in the tissues lining the human gut are central players involved in microbial sensing and shaping of appropriate adaptive immune responses. Probiotics are live microorganisms which...... when administered in adequate amounts confer a health benefit on the host. While the majority of probiotic microorganisms studied to date are lactic acid bacteria, research in yeasts with potentially beneficial influences on human health has mainly revolved around Saccharomyces boulardii. This yeast...... has shown a positive impact on disease outcome in clinical studies of inflammatory bowel disease, indicating an ability of S. boulardii to influence human immune responses underlying intestinal inflammation. Consequent to this focus on S. boulardii as the fundamental probiotic yeast, very little...

  3. Metallic Biosorption Using Yeasts in Continuous Systems

    Directory of Open Access Journals (Sweden)

    Karla Miriam Hernández Mata

    2013-01-01

    Full Text Available Mining effluents were found to be the main source of pollution by heavy metals of the surface water in the San Pedro River in Sonora, Mexico. The overall objective of this study was to determine the biosorption of Zn, Cu, Mn, and Fe with yeasts isolated from San Pedro River in a continuous system. The tests conducted in two reactors packed with zeolite connected in series. The first reactor was inoculated mixing two yeasts species, and the effluent of the first reactor was fed to second reactor. Subsequently, the first reactor was fed with contaminated water of San Pedro River and effluent from this was the second reactor influent. After 40 days of the experiment a reduction of 81.5% zinc, 76.5% copper, manganese 95.5%, and 99.8% of iron was obtained. These results show that the selected yeasts are capable of biosorbing zinc, copper, manganese, and iron under these conditions.

  4. Yeasts and yeast-like organisms associated with fruits and blossoms of different fruit trees.

    Science.gov (United States)

    Vadkertiová, Renáta; Molnárová, Jana; Vránová, Dana; Sláviková, Elena

    2012-12-01

    Yeasts are common inhabitants of the phyllosphere, but our knowledge of their diversity in various plant organs is still limited. This study focused on the diversity of yeasts and yeast-like organisms associated with matured fruits and fully open blossoms of apple, plum, and pear trees, during 2 consecutive years at 3 localities in southwest Slovakia. The occurrence of yeasts and yeast-like organisms in fruit samples was 2½ times higher and the yeast community more diverse than that in blossom samples. Only 2 species (Aureobasidium pullulans and Metschnikowia pulcherrima) occurred regularly in the blossom samples, whereas Galactomyces candidus, Hanseniaspora guilliermondii, Hanseniaspora uvarum, M. pulcherrima, Pichia kluyveri, Pichia kudriavzevii, and Saccharomyces cerevisiae were the most frequently isolated species from the fruit samples. The ratio of the number of samples where only individual species were present to the number of samples where 2 or more species were found (consortium) was counted. The occurrence of individual species in comparison with consortia was much higher in blossom samples than in fruit samples. In the latter, consortia predominated. Aureobasidium pullulans, M. pulcherrima, and S. cerevisiae, isolated from both the fruits and blossoms, can be considered as resident yeast species of various fruit tree species cultivated in southwest Slovakia localities.

  5. New yeasts-new brews: modern approaches to brewing yeast design and development.

    Science.gov (United States)

    Gibson, B; Geertman, J-M A; Hittinger, C T; Krogerus, K; Libkind, D; Louis, E J; Magalhães, F; Sampaio, J P

    2017-06-01

    The brewing industry is experiencing a period of change and experimentation largely driven by customer demand for product diversity. This has coincided with a greater appreciation of the role of yeast in determining the character of beer and the widespread availability of powerful tools for yeast research. Genome analysis in particular has helped clarify the processes leading to domestication of brewing yeast and has identified domestication signatures that may be exploited for further yeast development. The functional properties of non-conventional yeast (both Saccharomyces and non-Saccharomyces) are being assessed with a view to creating beers with new flavours as well as producing flavoursome non-alcoholic beers. The discovery of the psychrotolerant S. eubayanus has stimulated research on de novo S. cerevisiae × S. eubayanus hybrids for low-temperature lager brewing and has led to renewed interest in the functional importance of hybrid organisms and the mechanisms that determine hybrid genome function and stability. The greater diversity of yeast that can be applied in brewing, along with an improved understanding of yeasts' evolutionary history and biology, is expected to have a significant and direct impact on the brewing industry, with potential for improved brewing efficiency, product diversity and, above all, customer satisfaction. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  6. Yeast Infection Test: MedlinePlus Lab Test Information

    Science.gov (United States)

    ... cheese-like discharge Painful urination Redness in the vagina Yeast infection of the penis may cause: Redness Scaling Rash ... on the location of your symptoms: If a vaginal yeast infection is suspected , your health care provider will perform ...

  7. Oleaginous yeasts: Promising platforms for the production of oleochemicals and biofuels.

    Science.gov (United States)

    Adrio, José L

    2017-09-01

    Oleaginous yeasts have a unique physiology that makes them the best suited hosts for the production of lipids, oleochemicals, and diesel-like fuels. Their high lipogenesis, capability of growing on many different carbon sources (including lignocellulosic sugars), easy large-scale cultivation, and an increasing number of genetic tools are some of the advantages that have encouraged their use to develop sustainable processes. This mini-review summarizes the metabolic engineering strategies developed in oleaginous yeasts within the last 2 years to improve process metrics (titer, yield, and productivity) for the production of lipids, free fatty acids, fatty acid-based chemicals (e.g., fatty alcohols, fatty acid ethyl esters), and alkanes. During this short period of time, tremendous progress has been made in Yarrowia lipolytica, the model oleaginous yeast, which has been engineered to improve lipid production by different strategies including increasing lipogenic pathway flux and biosynthetic precursors, and blocking degradation pathways. Moreover, remarkable advances have also been reported in Rhodosporidium toruloides and Lipomyces starkey despite the limited genetic tools available for these two very promising hosts. Biotechnol. Bioeng. 2017;114: 1915-1920. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  8. Cell-autonomous mechanisms of chronological aging in the yeast Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    Anthony Arlia-Ciommo

    2014-05-01

    Full Text Available A body of evidence supports the view that the signaling pathways governing cellular aging – as well as mechanisms of their modulation by longevity-extending genetic, dietary and pharmacological interventions - are conserved across species. The scope of this review is to critically analyze recent advances in our understanding of cell-autonomous mechanisms of chronological aging in the budding yeast Saccharomyces cerevisiae. Based on our analysis, we propose a concept of a biomolecular network underlying the chronology of cellular aging in yeast. The concept posits that such network progresses through a series of lifespan checkpoints. At each of these checkpoints, the intracellular concentrations of some key intermediates and products of certain metabolic pathways - as well as the rates of coordinated flow of such metabolites within an intricate network of intercompartmental communications - are monitored by some checkpoint-specific ′′master regulator′′ proteins. The concept envisions that a synergistic action of these master regulator proteins at certain early-life and late-life checkpoints modulates the rates and efficiencies of progression of such processes as cell metabolism, growth, proliferation, stress resistance, macromolecular homeostasis, survival and death. The concept predicts that, by modulating these vital cellular processes throughout lifespan (i.e., prior to an arrest of cell growth and division, and following such arrest, the checkpoint-specific master regulator proteins orchestrate the development and maintenance of a pro- or anti-aging cellular pattern and, thus, define longevity of chronologically aging yeast.

  9. Cell-autonomous mechanisms of chronological aging in the yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    Arlia-Ciommo, Anthony; Leonov, Anna; Piano, Amanda; Svistkova, Veronika; Titorenko, Vladimir I

    2014-05-27

    A body of evidence supports the view that the signaling pathways governing cellular aging - as well as mechanisms of their modulation by longevity-extending genetic, dietary and pharmacological interventions - are conserved across species. The scope of this review is to critically analyze recent advances in our understanding of cell-autonomous mechanisms of chronological aging in the budding yeast Saccharomyces cerevisiae . Based on our analysis, we propose a concept of a biomolecular network underlying the chronology of cellular aging in yeast. The concept posits that such network progresses through a series of lifespan checkpoints. At each of these checkpoints, the intracellular concentrations of some key intermediates and products of certain metabolic pathways - as well as the rates of coordinated flow of such metabolites within an intricate network of intercompartmental communications - are monitored by some checkpoint-specific "master regulator" proteins. The concept envisions that a synergistic action of these master regulator proteins at certain early-life and late-life checkpoints modulates the rates and efficiencies of progression of such processes as cell metabolism, growth, proliferation, stress resistance, macromolecular homeostasis, survival and death. The concept predicts that, by modulating these vital cellular processes throughout lifespan (i.e., prior to an arrest of cell growth and division, and following such arrest), the checkpoint-specific master regulator proteins orchestrate the development and maintenance of a pro- or anti-aging cellular pattern and, thus, define longevity of chronologically aging yeast.

  10. Mitochondrion-mediated cell death: dissecting yeast apoptosis for a better understanding of neurodegeneration

    International Nuclear Information System (INIS)

    Braun, Ralf J.

    2012-01-01

    Mitochondrial damage and dysfunction are common hallmarks for neurodegenerative disorders, including Alzheimer, Parkinson, Huntington diseases, and the motor neuron disorder amyotrophic lateral sclerosis. Damaged mitochondria pivotally contribute to neurotoxicity and neuronal cell death in these disorders, e.g., due to their inability to provide the high energy requirements for neurons, their generation of reactive oxygen species (ROS), and their induction of mitochondrion-mediated cell death pathways. Therefore, in-depth analyses of the underlying molecular pathways, including cellular mechanisms controlling the maintenance of mitochondrial function, is a prerequisite for a better understanding of neurodegenerative disorders. The yeast Saccharomyces cerevisiae is an established model for deciphering mitochondrial quality control mechanisms and the distinct mitochondrial roles during apoptosis and programmed cell death. Cell death upon expression of various human neurotoxic proteins has been characterized in yeast, revealing neurotoxic protein-specific differences. This review summarizes how mitochondria are affected in these neurotoxic yeast models, and how they are involved in the execution and prevention of cell death. I will discuss to which extent this mimics the situation in other neurotoxic model systems, and how this may contribute to a better understanding of the mitochondrial roles in the human disorders.

  11. Mitochondrion-mediated cell death: dissecting yeast apoptosis for a better understanding of neurodegeneration

    Energy Technology Data Exchange (ETDEWEB)

    Braun, Ralf J., E-mail: ralf.braun@uni-bayreuth.de [Institut für Zellbiologie, Universität Bayreuth, Bayreuth (Germany)

    2012-11-28

    Mitochondrial damage and dysfunction are common hallmarks for neurodegenerative disorders, including Alzheimer, Parkinson, Huntington diseases, and the motor neuron disorder amyotrophic lateral sclerosis. Damaged mitochondria pivotally contribute to neurotoxicity and neuronal cell death in these disorders, e.g., due to their inability to provide the high energy requirements for neurons, their generation of reactive oxygen species (ROS), and their induction of mitochondrion-mediated cell death pathways. Therefore, in-depth analyses of the underlying molecular pathways, including cellular mechanisms controlling the maintenance of mitochondrial function, is a prerequisite for a better understanding of neurodegenerative disorders. The yeast Saccharomyces cerevisiae is an established model for deciphering mitochondrial quality control mechanisms and the distinct mitochondrial roles during apoptosis and programmed cell death. Cell death upon expression of various human neurotoxic proteins has been characterized in yeast, revealing neurotoxic protein-specific differences. This review summarizes how mitochondria are affected in these neurotoxic yeast models, and how they are involved in the execution and prevention of cell death. I will discuss to which extent this mimics the situation in other neurotoxic model systems, and how this may contribute to a better understanding of the mitochondrial roles in the human disorders.

  12. Yeast genes involved in regulating cysteine uptake affect production of hydrogen sulfide from cysteine during fermentation.

    Science.gov (United States)

    Huang, Chien-Wei; Walker, Michelle E; Fedrizzi, Bruno; Gardner, Richard C; Jiranek, Vladimir

    2017-08-01

    An early burst of hydrogen sulfide (H2S) produced by Saccharomyces cerevisiae during fermentation could increase varietal thiols and therefore enhance desirable tropical aromas in varieties such as Sauvignon Blanc. Here we attempted to identify genes affecting H2S formation from cysteine by screening yeast deletion libraries via a colony colour assay on media resembling grape juice. Both Δlst4 and Δlst7 formed lighter coloured colonies and produced significantly less H2S than the wild type on high concentrations of cysteine, likely because they are unable to take up cysteine efficiently. We then examined the nine known cysteine permeases and found that deletion of AGP1, GNP1 and MUP1 led to reduced production of H2S from cysteine. We further showed that deleting genes involved in the SPS-sensing pathway such as STP1 and DAL81 also reduced H2S from cysteine. Together, this study indirectly confirms that Agp1p, Gnp1p and Mup1p are the major cysteine permeases and that they are regulated by the SPS-sensing and target of rapamycin pathways under the grape juice-like, cysteine-supplemented, fermentation conditions. The findings highlight that cysteine transportation could be a limiting factor for yeast to generate H2S from cysteine, and therefore selecting wine yeasts without defects in cysteine uptake could maximise thiol production potential. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. Autophagy: one more Nobel Prize for yeast

    Directory of Open Access Journals (Sweden)

    Andreas Zimmermann

    2016-12-01

    Full Text Available The recent announcement of the 2016 Nobel Prize in Physiology or Medicine, awarded to Yoshinori Ohsumi for the discoveries of mechanisms governing autophagy, underscores the importance of intracellular degradation and recycling. At the same time, it further cements yeast, in which this field decisively developed, as a prolific model organism. Here we provide a quick historical overview that mirrors both the importance of autophagy as a conserved and essential process for cellular life and death as well as the crucial role of yeast in its mechanistic characterization.

  14. Characterization of wine yeasts for ethanol production

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez, J.; Benitez, T.

    1986-11-01

    Selected wine yeasts were tested for their ethanol and sugar tolerance, and for their fermentative capacity. Growth (..mu..) and fermentation rates (..nu..) were increasingly inhibited by increasing ethanol and glucose concentrations, ''flor'' yeasts being the least inhibited. Except in the latter strains, the ethanol production rate was accelerated by adding the glucose stepwise. The best fermenting strains selected in laboratory medium were also the best at fermenting molasses. Invertase activity was not a limiting step in ethanol production, ..nu.. being accelerated by supplementing molasses with ammonia and biotine, and by cell recycle.

  15. A Genetics Laboratory Module Involving Selection and Identification of Lysine Synthesis Mutants in the Yeast Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    Jill B. Keeney

    2009-12-01

    Full Text Available We have developed a laboratory exercise, currently being used with college sophomores, which uses the yeast Saccharomyces cerevisiae to convey the concepts of amino acid biosynthesis, mutation, and gene complementation. In brief, selective medium is used to isolate yeast cells carrying a mutation in the lysine biosynthesis pathway. A spontaneous mutation in any one of three separate genetic loci will allow for growth on selective media; however, the frequency of mutations isolated from each locus differs. Following isolation of a mutated strain, students use complementation analysis to identify which gene contains the mutation. Since the yeast genome has been mapped and sequenced, students with access to the Internet can then research and develop hypotheses to explain the differences in frequencies of mutant genes obtained.

  16. Integrated approach for selecting efficient Saccharomyces cerevisiae for industrial lignocellulosic fermentations: Importance of yeast chassis linked to process conditions.

    Science.gov (United States)

    Costa, Carlos E; Romaní, Aloia; Cunha, Joana T; Johansson, Björn; Domingues, Lucília

    2017-03-01

    In this work, four robust yeast chassis isolated from industrial environments were engineered with the same xylose metabolic pathway. The recombinant strains were physiologically characterized in synthetic xylose and xylose-glucose medium, on non-detoxified hemicellulosic hydrolysates of fast-growing hardwoods (Eucalyptus and Paulownia) and agricultural residues (corn cob and wheat straw) and on Eucalyptus hydrolysate at different temperatures. Results show that the co-consumption of xylose-glucose was dependent on the yeast background. Moreover, heterogeneous results were obtained among different hydrolysates and temperatures for each individual strain pointing to the importance of designing from the very beginning a tailor-made yeast considering the specific raw material and process. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Dietary Yeast Cell Wall Extract Alters the Proteome of the Skin Mucous Barrier in Atlantic Salmon (Salmo salar: Increased Abundance and Expression of a Calreticulin-Like Protein.

    Directory of Open Access Journals (Sweden)

    Giulia Micallef

    Full Text Available In order to improve fish health and reduce use of chemotherapeutants in aquaculture production, the immunomodulatory effect of various nutritional ingredients has been explored. In salmon, there is evidence that functional feeds can reduce the abundance of sea lice. This study aimed to determine if there were consistent changes in the skin mucus proteome that could serve as a biomarker for dietary yeast cell wall extract. The effect of dietary yeast cell wall extract on the skin mucus proteome of Atlantic salmon was examined using two-dimensional gel electrophoresis. Forty-nine spots showed a statistically significant change in their normalised volumes between the control and yeast cell wall diets. Thirteen spots were successfully identified by peptide fragment fingerprinting and LC-MS/MS and these belonged to a variety of functions and pathways. To assess the validity of the results from the proteome approach, the gene expression of a selection of these proteins was studied in skin mRNA from two different independent feeding trials using yeast cell wall extracts. A calreticulin-like protein increased in abundance at both the protein and transcript level in response to dietary yeast cell wall extract. The calreticulin-like protein was identified as a possible biomarker for yeast-derived functional feeds since it showed the most consistent change in expression in both the mucus proteome and skin transcriptome. The discovery of such a biomarker is expected to quicken the pace of research in the application of yeast cell wall extracts.

  18. Occurrence of Killer Yeast Strains in Fruit and Berry Wine Yeast Populations

    Directory of Open Access Journals (Sweden)

    Gintare Gulbiniene

    2004-01-01

    Full Text Available Apple, cranberry, chokeberry and Lithuanian red grape wine yeast populations were used for the determination of killer yeast occurrence. According to the tests of the killer characteristics and immunity the isolated strains were divided into seven groups. In this work the activity of killer toxins purified from some typical strains was evaluated. The analysed strains produced different amounts of active killer toxin and some of them possessed new industrially significant killer properties. Total dsRNA extractions in 11 killer strains of yeast isolated from spontaneous fermentations revealed that the molecular basis of the killer phenomenon was not only dsRNAs, but also unidentified genetic determinants.

  19. A Kinetic Modelling of Enzyme Inhibitions in the Central Metabolism of Yeast Cells

    Science.gov (United States)

    Kasbawati; Kalondeng, A.; Aris, N.; Erawaty, N.; Azis, M. I.

    2018-03-01

    Metabolic regulation plays an important role in the metabolic engineering of a cellular process. It is conducted to improve the productivity of a microbial process by identifying the important regulatory nodes of a metabolic pathway such as fermentation pathway. Regulation of enzymes involved in a particular pathway can be held to improve the productivity of the system. In the central metabolism of yeast cell, some enzymes are known as regulating enzymes that can be inhibited to increase the production of ethanol. In this research we study the kinetic modelling of the enzymes in the central pathway of yeast metabolism by taking into consideration the enzyme inhibition effects to the ethanol production. The existence of positive steady state solution and the stability of the system are also analysed to study the property and dynamical behaviour of the system. One stable steady state of the system is produced if some conditions are fulfilled. The conditions concern to the restriction of the maximum reactions of the enzymes in the pyruvate and acetaldehyde branch points. There exists a certain time of fermentation reaction at which a maximum and a minimum ethanol productions are attained after regulating the system. Optimal ethanol concentration is also produced for a certain initial concentration of inhibitor.

  20. Guidelines and recommendations on yeast cell death nomenclature

    OpenAIRE

    Carmona-Gutierrez, Didac; Bauer, Maria Anna; Zimmermann, Andreas; Aguilera, Andres; Austriaco, Nicanor; Sigrist, Stephan J.

    2018-01-01

    Elucidating the biology of yeast in its full complexity has major implications for science, medicine and industry. One of the most critical processes determining yeast life and physiology is cellular demise. However, the investigation of yeast cell death is a relatively young field, and a widely accepted set of concepts and terms is still missing. Here, we propose unified criteria for the definition of accidental, regulated, and programmed forms of cell death in yeast based on a series of mor...

  1. Effect of increasing growth temperature on yeast fermentation ...

    African Journals Online (AJOL)

    The effect of increasing growth temperature on yeast fermentation was studied at approximately 5 oC intervals over a range of 18 – 37 oC, using one strain each of ale, lager and wine yeast. The ale and wine yeasts grew at all the temperatures tested, but lager yeast failed to grow at 37 oC. All these strains gave lower ...

  2. Pleiotropic functions of the yeast Greatwall-family protein kinase Rim15p: a novel target for the control of alcoholic fermentation.

    Science.gov (United States)

    Watanabe, Daisuke; Takagi, Hiroshi

    2017-06-01

    Rim15p, a Greatwall-family protein kinase in yeast Saccharomyces cerevisiae, is required for cellular nutrient responses, such as the entry into quiescence and the induction of meiosis and sporulation. In higher eukaryotes, the orthologous gene products are commonly involved in the cell cycle G 2 /M transition. How are these pleiotropic functions generated from a single family of protein kinases? Recent advances in both research fields have identified the conserved Greatwall-mediated signaling pathway and a variety of downstream target molecules. In addition, our studies of S. cerevisiae sake yeast strains revealed that Rim15p also plays a significant role in the control of alcoholic fermentation. Despite an extensive history of research on glycolysis and alcoholic fermentation, there has been no critical clue to artificial modification of fermentation performance of yeast cells. Our finding of an in vivo metabolic regulatory mechanism is expected to provide a major breakthrough in yeast breeding technologies for fermentation applications.

  3. Proteolytic activities in yeast after UV irradiation. Pt. 2

    Energy Technology Data Exchange (ETDEWEB)

    Schwencke, J.; Moustacchi, E.

    1982-04-01

    When the levels of three common yeast proteinases in exponentially growing cells of mutants blocked in different repair pathways are compared to that of isogenic wild-type cells, it can be seen that the level of proteinase B is enhanced in the mutants whereas the levels of leucin aminopeptidase (Leu.AP) and lysine aminopeptidase (Lys.AP) are similar in all strains. As in its corresponding wild type, the level of proteinase B activity is further enhanced after UV-irradiation in a mutant blocked in excision-repair (rad1-3). In contrast, following the same treatment the level of proteinase B remains almost constant in a mutant blocked in a general error-prone repair system (rad6-1) and in a mutant defective in a more specific mutagenic repair pathway (pso2-1). Cycloheximide, an inhibitor of protein synthesis, blocks the post-UV enhancement in proteinase B activity observed in rad1-3 indicating that, as in the wild-type cells, an inducible process is involved. The levels of Lys.AP and Leu.AP are, respectively, either unaffected or only moderately increased following UV-treatment of the repair defective mutants, as in wild-type strains.

  4. Guidelines and recommendations on yeast cell death nomenclature

    NARCIS (Netherlands)

    Carmona-Gutierrez, Didac; Bauer, Maria Anna; Zimmermann, Andreas; Aguilera, Andrés; Austriaco, Nicanor; Ayscough, Kathryn; Balzan, Rena; Bar-Nun, Shoshana; Barrientos, Antonio; Belenky, Peter; Blondel, Marc; Braun, Ralf J; Breitenbach, Michael; Burhans, William C; Büttner, Sabrina; Cavalieri, Duccio; Chang, Michael; Cooper, Katrina F; Côrte-Real, Manuela; Costa, Vítor; Cullin, Christophe; Dawes, Ian; Dengjel, Jörn; Dickman, Martin B; Eisenberg, Tobias; Fahrenkrog, Birthe; Fasel, Nicolas; Fröhlich, Kai-Uwe; Gargouri, Ali; Giannattasio, Sergio; Goffrini, Paola; Gourlay, Campbell W; Grant, Chris M; Greenwood, Michael T; Guaragnella, Nicoletta; Heger, Thomas; Heinisch, Jürgen; Herker, Eva; Herrmann, Johannes M; Hofer, Sebastian; Jiménez-Ruiz, Antonio; Jungwirth, Helmut; Kainz, Katharina; Kontoyiannis, Dimitrios P; Ludovico, Paula; Manon, Stéphen; Martegani, Enzo; Mazzoni, Cristina; Megeney, Lynn A; Meisinger, Chris; Nielsen, Jens; Nyström, Thomas; Osiewacz, Heinz D; Outeiro, Tiago F; Park, Hay-Oak; Pendl, Tobias; Petranovic, Dina; Picot, Stephane; Polčic, Peter; Powers, Ted; Ramsdale, Mark; Rinnerthaler, Mark; Rockenfeller, Patrick; Ruckenstuhl, Christoph; Schaffrath, Raffael; Segovia, Maria; Severin, Fedor F; Sharon, Amir; Sigrist, Stephan J; Sommer-Ruck, Cornelia; Sousa, Maria João; Thevelein, Johan M; Thevissen, Karin; Titorenko, Vladimir; Toledano, Michel B; Tuite, Mick; Vögtle, F-Nora; Westermann, Benedikt; Winderickx, Joris; Wissing, Silke; Wölfl, Stefan; Zhang, Zhaojie J; Zhao, Richard Y; Zhou, Bing; Galluzzi, Lorenzo; Kroemer, Guido; Madeo, Frank

    2018-01-01

    Elucidating the biology of yeast in its full complexity has major implications for science, medicine and industry. One of the most critical processes determining yeast life and physiology is cel-lular demise. However, the investigation of yeast cell death is a relatively young field, and a widely

  5. Selection of oleaginous yeasts for fatty acid production

    NARCIS (Netherlands)

    Lamers, Dennis; Biezen, van Nick; Martens, Dirk; Peters, Linda; Zilver, van de Eric; Jacobs-van Dreumel, Nicole; Wijffels, René H.; Lokman, Christien

    2016-01-01

    Background: Oleaginous yeast species are an alternative for the production of lipids or triacylglycerides (TAGs). These yeasts are usually non-pathogenic and able to store TAGs ranging from 20 % to 70 % of their cell mass depending on culture conditions. TAGs originating from oleaginous yeasts

  6. Performance of baker's yeast produced using date syrup substrate ...

    African Journals Online (AJOL)

    Baker's yeast was produced from three selected baker's yeast strains using date syrup as a substrate at low and high flow rate compared to those produced using molasses substrates. Performance of the produced baker's yeasts on Arabic bread quality was investigated. Baking tests showed a positive relationship between ...

  7. Triacetic acid lactone production in industrial Saccharomyces yeast strains

    Science.gov (United States)

    Triacetic acid lactone (TAL) is a potential platform chemical that can be produced in yeast. To evaluate the potential for industrial yeast strains to produce TAL, the g2ps1 gene encoding 2-pyrone synthase was transformed into thirteen industrial yeast strains of varied genetic background. TAL produ...

  8. 21 CFR 573.750 - Pichia pastoris dried yeast.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Pichia pastoris dried yeast. 573.750 Section 573... Food Additive Listing § 573.750 Pichia pastoris dried yeast. (a) Identity. The food additive Pichia pastoris dried yeast may be used in feed formulations of broiler chickens as a source of protein not to...

  9. Prequels to Synthetic Biology: From Candidate Gene Identification and Validation to Enzyme Subcellular Localization in Plant and Yeast Cells.

    Science.gov (United States)

    Foureau, E; Carqueijeiro, I; Dugé de Bernonville, T; Melin, C; Lafontaine, F; Besseau, S; Lanoue, A; Papon, N; Oudin, A; Glévarec, G; Clastre, M; St-Pierre, B; Giglioli-Guivarc'h, N; Courdavault, V

    2016-01-01

    Natural compounds extracted from microorganisms or plants constitute an inexhaustible source of valuable molecules whose supply can be potentially challenged by limitations in biological sourcing. The recent progress in synthetic biology combined to the increasing access to extensive transcriptomics and genomics data now provide new alternatives to produce these molecules by transferring their whole biosynthetic pathway in heterologous production platforms such as yeasts or bacteria. While the generation of high titer producing strains remains per se an arduous field of investigation, elucidation of the biosynthetic pathways as well as characterization of their complex subcellular organization are essential prequels to the efficient development of such bioengineering approaches. Using examples from plants and yeasts as a framework, we describe potent methods to rationalize the study of partially characterized pathways, including the basics of computational applications to identify candidate genes in transcriptomics data and the validation of their function by an improved procedure of virus-induced gene silencing mediated by direct DNA transfer to get around possible resistance to Agrobacterium-delivery of viral vectors. To identify potential alterations of biosynthetic fluxes resulting from enzyme mislocalizations in reconstituted pathways, we also detail protocols aiming at characterizing subcellular localizations of protein in plant cells by expression of fluorescent protein fusions through biolistic-mediated transient transformation, and localization of transferred enzymes in yeast using similar fluorescence procedures. Albeit initially developed for the Madagascar periwinkle, these methods may be applied to other plant species or organisms in order to establish synthetic biology platform. © 2016 Elsevier Inc. All rights reserved.

  10. Tombusviruses upregulate phospholipid biosynthesis via interaction between p33 replication protein and yeast lipid sensor proteins during virus replication in yeast

    International Nuclear Information System (INIS)

    Barajas, Daniel; Xu, Kai; Sharma, Monika; Wu, Cheng-Yu; Nagy, Peter D.

    2014-01-01

    Positive-stranded RNA viruses induce new membranous structures and promote membrane proliferation in infected cells to facilitate viral replication. In this paper, the authors show that a plant-infecting tombusvirus upregulates transcription of phospholipid biosynthesis genes, such as INO1, OPI3 and CHO1, and increases phospholipid levels in yeast model host. This is accomplished by the viral p33 replication protein, which interacts with Opi1p FFAT domain protein and Scs2p VAP protein. Opi1p and Scs2p are phospholipid sensor proteins and they repress the expression of phospholipid genes. Accordingly, deletion of OPI1 transcription repressor in yeast has a stimulatory effect on TBSV RNA accumulation and enhanced tombusvirus replicase activity in an in vitro assay. Altogether, the presented data convincingly demonstrate that de novo lipid biosynthesis is required for optimal TBSV replication. Overall, this work reveals that a (+)RNA virus reprograms the phospholipid biosynthesis pathway in a unique way to facilitate its replication in yeast cells. - Highlights: • Tombusvirus p33 replication protein interacts with FFAT-domain host protein. • Tombusvirus replication leads to upregulation of phospholipids. • Tombusvirus replication depends on de novo lipid synthesis. • Deletion of FFAT-domain host protein enhances TBSV replication. • TBSV rewires host phospholipid synthesis

  11. Transcriptional reprogramming in yeast using dCas9 and combinatorial gRNA strategies

    DEFF Research Database (Denmark)

    Damgaard Jensen, Emil; Ferreira, Raphael; Jakociunas, Tadas

    2017-01-01

    on developing synthetic biology tools for orthogonal control of transcription. Most recently, the nuclease-deficient Cas9 (dCas9) has emerged as a flexible tool for controlling activation and repression of target genes, by the simple RNA-guided positioning of dCas9 in the vicinity of the target gene...... transcription start site. In this study we compared two different systems of dCas9-mediated transcriptional reprogramming, and applied them to genes controlling two biosynthetic pathways for biobased production of isoprenoids and triacylglycerols (TAGs) in baker's yeast Saccharomyces cerevisiae. By testing 101...... production and increases in TAG. Taken together, we show similar performance for a constitutive and an inducible dCas9 approach, and identify multiplex gRNA designs that can significantly perturb isoprenoid production and TAG profiles in yeast without editing the genomic context of the target genes. We also...

  12. Application of synthetic biology for production of chemicals in yeast Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Borodina, Irina; Li, Mingji

    2015-01-01

    Synthetic biology and metabolic engineering enable generation of novel cell factories that efficiently convert renewable feedstocks into biofuels, bulk, and fine chemicals, thus creating the basis for biosustainable economy independent on fossil resources. While over a hundred proof...... biology has the potential to bring down this cost by improving our ability to predictably engineer biological systems. This review highlights synthetic biology applications for design, assembly, and optimization of non-native biochemical pathways in baker's yeast Saccharomyces cerevisiae. We describe......-of-concept chemicals have been made in yeast, only a very small fraction of those has reached commercial-scale production so far. The limiting factor is the high research cost associated with the development of a robust cell factory that can produce the desired chemical at high titer, rate, and yield. Synthetic...

  13. Kinetics of gene and chromosome mutations induced by UV-C in yeast Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    Koltovaya, N.; Kokoreva, A.; Senchenko, D.; Shvaneva, N.; Zhuchkina, N.

    2017-01-01

    The systematic study of the kinetics of UV-induced gene and structural mutations in eukaryotic cells was carried out on the basis of model yeast S. cerevisiae. A variety of genetic assays (all types of base pair substitutions, frameshifts, forward mutations canl, chromosomal and plasmid rearrangements) in haploid strains were used. Yeast cells were treated by UV-C light of fluence of energy up to 200 J/m"2. The kinetics of the induced gene and structural mutations is represented by a linear-quadratic and exponential functions. The slope of curves in log-log plots was not constant, had the value 2-4 and depended on the interval of doses. It was suggested that it is the superposition and dynamics of different pathways form the mutagenic responses of eukaryotic cells to UV-C light that cause the high-order curves. [ru

  14. Biosynthesis of Astaxanthin as a Main Carotenoid in the Heterobasidiomycetous Yeast Xanthophyllomyces dendrorhous

    Directory of Open Access Journals (Sweden)

    Jose L. Barredo

    2017-07-01

    Full Text Available Carotenoids are organic lipophilic yellow to orange and reddish pigments of terpenoid nature that are usually composed of eight isoprene units. This group of secondary metabolites includes carotenes and xanthophylls, which can be naturally obtained from photosynthetic organisms, some fungi, and bacteria. One of the microorganisms able to synthesise carotenoids is the heterobasidiomycetous yeast Xanthophyllomyces dendrorhous, which represents the teleomorphic state of Phaffia rhodozyma, and is mainly used for the production of the xanthophyll astaxanthin. Upgraded knowledge on the biosynthetic pathway of the main carotenoids synthesised by X. dendrorhous, the biotechnology-based improvement of astaxanthin production, as well as the current omics approaches available in this yeast are reviewed in depth.

  15. Global analysis of the yeast osmotic stress response by quantitative proteomics

    DEFF Research Database (Denmark)

    Soufi, Boumediene; Kelstrup, C.D.; Stoehr, G.

    2009-01-01

    a comprehensive, quantitative, and time-resolved analysis using high-resolution mass spectrometry of phospho-proteome and proteome changes in response to osmotic stress in yeast. We identified 5534 unique phosphopeptide variants and 3383 yeast proteins. More than 15% of the detected phosphorylation site status...... changed more than two-fold within 5 minutes of treatment. Many of the corresponding phosphoproteins are involved in the early response to environmental stress. Surprisingly, we find that 158 regulated phosphorylation sites are potential substrates of basophilic kinases as opposed to the classical proline......-directed MAP kinase network implicated in stress response mechanisms such as p38 and HOG pathways. Proteome changes reveal an increase in abundance of more than one hundred proteins after 20 min of salt stress. Many of these are involved in the cellular response to increased osmolarity, which include proteins...

  16. Yeast Interacting Proteins Database: YFR015C, YJL137C [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available yeast homolog; expression induced by glucose limitation, nitrogen starvation, environmental stress, and entr...pression induced by glucose limitation, nitrogen starvation, environmental stress, and entry into stationary

  17. Yeast mother cell-specific aging

    Czech Academy of Sciences Publication Activity Database

    Breitenbach, M.; Laun, P.; Pichová, Alena; Madeo, F.; Heeren, G.; Kohlwein, S. D.; Froehlich, K. U.; Dawes, I.

    2001-01-01

    Roč. 18, - (2001), s. 21 ISSN 0749-503X. [International Conference on Yeast Genetics and Molecular Biology /20./. 26.08.2001-31.08.2001, Prague] Institutional research plan: CEZ:AV0Z5020903 Subject RIV: EB - Genetics ; Molecular Biology

  18. Xylitol production from colombian native yeast strains

    Directory of Open Access Journals (Sweden)

    Isleny Andrea Vanegas Córdoba

    2004-07-01

    Full Text Available Xylitol is an alternative sweetener with similar characteristics to sucrose that has become of great interest, due mainly to its safe use in diabetic patients and those deficient in glucose-6-phosphate-dehydrogenase. Its chemical production is expensive and generates undesirable by-products, whereas biotechnological process, which uses different yeasts genera, is a viable production alternative because it is safer and specific. Colombia has a privilege geographic location and offers a great microbial variety, this can be taken advantage of with academic and commercial goals. Because of this, some native microorganisms with potential to produce xylitol were screened in this work. It were isolated 25 yeasts species, from which was possible to identify 84% by the kit API 20C-AUX. Three yeasts: Candida kefyr, C. tropicalis y C. parapsilosis presented greater capacity to degrade xylose compared to the others, therefore they were selected for the later evaluation of its productive capacity. Discontinuous cellular cultures were developed in shaken flasks at 200 rpm and 35°C by 30 hours, using synthetic media with xylose as carbon source. Xylose consumption and xylitol production were evaluated by thin layer chromatography and high performance liquid chromatography. The maximal efficiency were obtained with Candida kefyr and C. tropicalis (Yp/s 0.5 y 0.43 g/g, respectively, using an initial xylose concentration of 20 g/L. Key words: Xylitol, xylose, yeasts, Candida kefyr, C. tropicalis, C. parapsilosis.

  19. Yeast metabolic engineering for hemicellulosic ethanol production

    Science.gov (United States)

    Jennifer Van Vleet; Thomas W. Jeffries

    2009-01-01

    Efficient fermentation of hemicellulosic sugars is critical for the bioconversion of lignocellulosics to ethanol. Efficient sugar uptake through the heterologous expression of yeast and fungal xylose/glucose transporters can improve fermentation if other metabolic steps are not rate limiting. Rectification of cofactor imbalances through heterologous expression of...

  20. Uncommon opportunistic yeast bloodstream infections from Qatar

    NARCIS (Netherlands)

    Taj-Aldeen, S.J.; AbdulWahab, A.; Kolecka, A.; Deshmukh, A.; Meis, J.F.G.M.; Boekhout, T.

    2014-01-01

    Eleven uncommon yeast species that are associated with high mortality rates irrespective of antifungal therapy were isolated from 17/187 (201 episodes) pediatric and elderly patients with fungemia from Qatar. The samples were taken over a 6-year period (January 2004-December 2010). Isolated species

  1. Ethanol fermentation with a flocculating yeast

    Energy Technology Data Exchange (ETDEWEB)

    Admassu, W; Korus, R A; Heimsch, R C

    1985-08-01

    A 100 cm x 5.7 cm internal diameter tower fermentor was fabricated and operated continuously for 11 months using the floc-forming yeast, Saccharomyces cerevisiae (American Type Culture Collection 4097). Steady state operation of the system was characterized at 32/sup 0/C and pH 4.0 for glucose concentrations ranging from 105 to 215 g l/sup -1/. The height of the yeast bed in the tower was maintained at 80 cm. The high yeast density, ethanol concentration and low pH prevented bacterial contamination in the reactor. The concentration profiles of glucose and ethanol within the bed were described by a dispersion model. Modeling parameters were determined for the yeast by batch kinetics and tracer experiments. The kinetic model included ethanol inhibition and substrate limitation. A tracer study with step input of D-xylose (a non-metabolizable sugar for S. cerevisiae) determined the dispersion number (D/uL=0.16) and liquid voidage (epsilonsub(L)=0.25). Measurements taken after 6 months of continuous operation indicated that there was no significant change in fermentor performance.

  2. Analysis of RNA metabolism in fission yeast

    DEFF Research Database (Denmark)

    Wise, Jo Ann; Nielsen, Olaf

    2017-01-01

    Here we focus on the biogenesis and function of messenger RNA (mRNA) in fission yeast cells. Following a general introduction that also briefly touches on other classes of RNA, we provide an overview of methods used to analyze mRNAs throughout their life cycles....

  3. UBA domain containing proteins in fission yeast

    DEFF Research Database (Denmark)

    Hartmann-Petersen, Rasmus; Semple, Colin A M; Ponting, Chris P

    2003-01-01

    characterised on both the functional and structural levels. One example of a widespread ubiquitin binding module is the ubiquitin associated (UBA) domain. Here, we discuss the approximately 15 UBA domain containing proteins encoded in the relatively small genome of the fission yeast Schizosaccharomyces pombe...

  4. Vaginal yeast infections in diabetic women

    African Journals Online (AJOL)

    could we implicate either trichomoniasis or candidiasis as causes ofthese symptoms (Table I). It is possible that in some instances yeasts may have been missed on cul- ture since it has been estimated that at least 10' cfu/m! are required for a culture to be positive.15 Gardnerella vaginalis was not sought in this study and ...

  5. Phosphorylation site on yeast pyruvate dehydrogenase complex

    International Nuclear Information System (INIS)

    Uhlinger, D.J.

    1986-01-01

    The pyruvate dehydrogenase complex was purified to homogeneity from baker's yeast (Saccharomyces cerevisiae). Yeast cells were disrupted in a Manton-Gaulin laboratory homogenizer. The pyruvate dehydrogenase complex was purified by fractionation with polyethylene glycol, isoelectric precipitation, ultracentrifugation and chromatography on hydroxylapatite. Final purification of the yeast pyruvate dehydrogenase complex was achieved by cation-exchange high pressure liquid chromatography (HPLC). No endogenous pyruvate dehydrogenase kinase activity was detected during the purification. However, the yeast pyruvate dehydrogenase complex was phosphorylated and inactivated with purified pyruvate dehydrogenase kinase from bovine kidney. Tryptic digestion of the 32 P-labeled complex yielded a single phosphopeptide which was purified to homogeniety. The tryptic digest was subjected to chromatography on a C-18 reverse phase HPLC column with a linear gradient of acetonitrile. Radioactive fractions were pooled, concentrated, and subjected to anion-exchange HPLC. The column was developed with a linear gradient of ammonium acetate. Final purification of the phosphopeptide was achieved by chromatography on a C-18 reverse phase HPLC column developed with a linear gradient of acetonitrile. The amino acid sequence of the homogeneous peptide was determined by manual modified Edman degradation

  6. Functional differences in yeast protein disulfide isomerases

    DEFF Research Database (Denmark)

    Nørgaard, P; Westphal, V; Tachibana, C

    2001-01-01

    PDI1 is the essential gene encoding protein disulfide isomerase in yeast. The Saccharomyces cerevisiae genome, however, contains four other nonessential genes with homology to PDI1: MPD1, MPD2, EUG1, and EPS1. We have investigated the effects of simultaneous deletions of these genes. In several...

  7. Catalytic site interactions in yeast OMP synthase

    DEFF Research Database (Denmark)

    Hansen, Michael Riis; Barr, Eric W.; Jensen, Kaj Frank

    2014-01-01

    45 (2006) 5330-5342]. This behavior was investigated in the yeast enzyme by mutations in the conserved catalytic loop and 5-phosphoribosyl-1-diphosphate (PRPP) binding motif. Although the reaction is mechanistically sequential, the wild-type (WT) enzyme shows parallel lines in double reciprocal...

  8. Hybridization of Palm Wine Yeasts ( Saccharomyces Cerevisiae ...

    African Journals Online (AJOL)

    Haploid auxotrophic strains of Saccharomyces cerevisiae were selected from palm wine and propagated by protoplast fusion with Brewers yeast. Fusion resulted in an increase in both ethanol production and tolerance against exogenous ethanol. Mean fusion frequencies obtained for a mating types ranged between 8 x ...

  9. Effect of yeast storage temperature and flour composition on fermentative activities of baker's yeast

    Directory of Open Access Journals (Sweden)

    Pejin Dušanka J.

    2009-01-01

    Full Text Available Baker's yeast is a set of living cells of Saccharomyces cerevisiae. It contains around 70-72% of water, 42-45% of proteins, around 40% of carbohydrates, around 7.5% of lipids (based on dry matter, and vitamin B-complex. On the basis of yeast cell analysis it can be concluded that yeast is a complex biological system which changes in time. The intensity of the changes depends on temperature. Yeast sample was stored at 4°C i 24°C for 12 days. During storage at 4°C, the content of total carbohydrates decreased from 48.81% to 37.50% (dry matter, whereas carbohydrate loss ranged from 40.81% to 29.28% at 24°C. The content of trehalose was 12.33% in the yeast sample stored at 4°C and 0.24% at 24°C. Loss of fermentative activity was 81.76% in the sample stored at 24°C for 12 days. The composition of five samples of 1st category flour was investigated. It was found that flours containing more reducing sugars and maltose enable higher fermentation activities. The flours with higher ash content (in the range 0.5-0.94% had higher contents of phytic acid. Higher ash and phytic contents in flour increased the yeast fermentative efficiency. In bakery industry, a range of ingredients has been applied to improve the product's quality such as surface active substances (emulsifiers, enzymes, sugars and fats. In the paper, the effect of some ingredients added to dough (margarine, saccharose, sodium chloride and malted barley on the yeast fermentative activity was studied. The mentioned ingredients were added to dough at different doses: 0.5, 1.0, 1.5 and 2.0%, flour basis. It was found that the investigated ingredients affected the fermentative activity of yeast and improved the bread quality.

  10. Yeast cell differentiation: Lessons from pathogenic and non-pathogenic yeasts.

    Science.gov (United States)

    Palková, Zdena; Váchová, Libuše

    2016-09-01

    Yeasts, historically considered to be single-cell organisms, are able to activate different differentiation processes. Individual yeast cells can change their life-styles by processes of phenotypic switching such as the switch from yeast-shaped cells to filamentous cells (pseudohyphae or true hyphae) and the transition among opaque, white and gray cell-types. Yeasts can also create organized multicellular structures such as colonies and biofilms, and the latter are often observed as contaminants on surfaces in industry and medical care and are formed during infections of the human body. Multicellular structures are formed mostly of stationary-phase or slow-growing cells that diversify into specific cell subpopulations that have unique metabolic properties and can fulfill specific tasks. In addition to the development of multiple protective mechanisms, processes of metabolic reprogramming that reflect a changed environment help differentiated individual cells and/or community cell constituents to survive harmful environmental attacks and/or to escape the host immune system. This review aims to provide an overview of differentiation processes so far identified in individual yeast cells as well as in multicellular communities of yeast pathogens of the Candida and Cryptococcus spp. and the Candida albicans close relative, Saccharomyces cerevisiae. Molecular mechanisms and extracellular signals potentially involved in differentiation processes are also briefly mentioned. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. A chloroplast pathway for the de novo biosynthesis of triacylglycerol in Chlamydomonas reinhardtii

    Energy Technology Data Exchange (ETDEWEB)

    Fan, J.; Xu, C.; Andre, C.

    2011-06-23

    Neutral lipid metabolism has been extensively studied in yeast, plants and mammals. In contrast, little information is available regarding the biochemical pathway, enzymes and regulatory factors involved in the biosynthesis of triacylglycerol (TAG) in microalgae. In the conventional TAG biosynthetic pathway widely accepted for yeast, plants and mammals, TAG is assembled in the endoplasmic reticulum (ER) from its immediate precursor diacylglycerol (DAG) made by ER-specific acyltransferases, and is deposited exclusively in lipid droplets in the cytosol. Here, we demonstrated that the unicellular microalga Chlamydomonas reinhardtii employs a distinct pathway that uses DAG derived almost exclusively from the chloroplast to produce TAG. This unique TAG biosynthesis pathway is largely dependent on de novo fatty acid synthesis, and the TAG formed in this pathway is stored in lipid droplets in both the chloroplast and the cytosol. These findings have wide implications for understanding TAG biosynthesis and storage and other areas of lipid metabolism in microalgae and other organisms.

  12. Synthetic lethality between gene defects affecting a single non-essential molecular pathway with reversible steps.

    Directory of Open Access Journals (Sweden)

    Andrei Zinovyev

    2013-04-01

    Full Text Available Systematic analysis of synthetic lethality (SL constitutes a critical tool for systems biology to decipher molecular pathways. The most accepted mechanistic explanation of SL is that the two genes function in parallel, mutually compensatory pathways, known as between-pathway SL. However, recent genome-wide analyses in yeast identified a significant number of within-pathway negative genetic interactions. The molecular mechanisms leading to within-pathway SL are not fully understood. Here, we propose a novel mechanism leading to within-pathway SL involving two genes functioning in a single non-essential pathway. This type of SL termed within-reversible-pathway SL involves reversible pathway steps, catalyzed by different enzymes in the forward and backward directions, and kinetic trapping of a potentially toxic intermediate. Experimental data with recombinational DNA repair genes validate the concept. Mathematical modeling recapitulates the possibility of kinetic trapping and revealed the potential contributions of synthetic, dosage-lethal interactions in such a genetic system as well as the possibility of within-pathway positive masking interactions. Analysis of yeast gene interaction and pathway data suggests broad applicability of this novel concept. These observations extend the canonical interpretation of synthetic-lethal or synthetic-sick interactions with direct implications to reconstruct molecular pathways and improve therapeutic approaches to diseases such as cancer.

  13. Baker's yeast: production of D- and L-3-hydroxy esters

    DEFF Research Database (Denmark)

    Dahl, Allan Carsten; Madsen, Jørgen Øgaard

    1998-01-01

    harvested while growing. In contrast, the stereoselectivity was shifted towards L-hydroxy esters when the oxo esters were added slowly to ordinary baker's yeast supplied with gluconolactone as co-substrate. The reduction rate with gluconolactone was increased by active aeration. Ethyl L-(S)-3......Baker's yeast grown under oxygen limited conditions and used in the reduction of 3-oxo esters results in a shift of the stereoselectivity of the yeast towards D-hydroxy esters as compared with ordinary baker's yeast. The highest degree of stereoselectivity was obtained with growing yeast or yeast......-hydroxybutanoate was afforded in >99% ee. Both enantiomers of ethyl 3-hydroxypentanoate, D-(R) in 96% ee and L-(S) in 93% ee, and of ethyl 4-chloro-3-hydroxybutanoate, D-(S) in 98% ee and L-(R) in 94% ee, were obtained. The results demonstrate that the stereoselectivity of baker's yeast can be controlled...

  14. Between science and industry-applied yeast research.

    Science.gov (United States)

    Korhola, Matti

    2018-03-01

    I was fortunate to enter yeast research at the Alko Research Laboratories with a strong tradition in yeast biochemistry and physiology studies. At the same time in the 1980s there was a fundamental or paradigm change in molecular biology research with discoveries in DNA sequencing and other analytical and physical techniques for studying macromolecules and cells. Since that time biotechnological research has expanded the traditional fermentation industries to efficient production of industrial and other enzymes and specialty chemicals. Our efforts were directed towards improving the industrial production organisms: minerals enriched yeasts (Se, Cr, Zn) and high glutathione content yeast, baker´s, distiller´s, sour dough and wine yeasts, and the fungal Trichoderma reesei platform for enzyme production. I am grateful for the trust of my colleagues in several leadership positions at the Alko Research Laboratories, Yeast Industry Platform and at the international yeast community.

  15. Full Data of Yeast Interacting Proteins Database (Original Version) - Yeast Interacting Proteins Database | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available List Contact us Yeast Interacting Proteins Database Full Data of Yeast Interacting Proteins Database (Origin...al Version) Data detail Data name Full Data of Yeast Interacting Proteins Database (Original Version) DOI 10....18908/lsdba.nbdc00742-004 Description of data contents The entire data in the Yeast Interacting Proteins Database...eir interactions are required. Several sources including YPD (Yeast Proteome Database, Costanzo, M. C., Hoga...ematic name in the SGD (Saccharomyces Genome Database; http://www.yeastgenome.org /). Bait gene name The gen

  16. Yeast Biodiversity from DOQ Priorat Uninoculated Fermentations.

    Science.gov (United States)

    Padilla, Beatriz; García-Fernández, David; González, Beatriz; Izidoro, Iara; Esteve-Zarzoso, Braulio; Beltran, Gemma; Mas, Albert

    2016-01-01

    Climate, soil, and grape varieties are the primary characteristics of terroir and lead to the definition of various appellations of origin. However, the microbiota associated with grapes are also affected by these conditions and can leave a footprint in a wine that will be part of the characteristics of terroir. Thus, a description of the yeast microbiota within a vineyard is of interest not only to provide a better understanding of the winemaking process, but also to understand the source of microorganisms that maintain a microbial footprint in wine from the examined vineyard. In this study, two typical grape varieties, Grenache and Carignan, have been sampled from four different vineyards in the DOQ Priorat winegrowing region. Afterward, eight spontaneous alcoholic fermentations containing only grapes from one sampling point and of one variety were conducted at laboratory scale. The fermentation kinetics and yeast population dynamics within each fermentation experiment were evaluated. Yeast identification was performed by RFLP-PCR of the 5.8S-ITS region and by sequencing D1/D2 of the 26S rRNA gene of the isolates. The fermentation kinetics did not indicate clear differences between the two varieties of grapes or among vineyards. Approximately 1,400 isolates were identified, exhibiting high species richness in some fermentations. Of all the isolates studied, approximately 60% belong to the genus Hanseniaspora, 16% to Saccharomyces, and 11% to Candida. Other minor genera, such as Hansenula, Issatchenkia, Kluyveromyces, Saccharomycodes, and Zygosaccharomyces, were also found. The distribution of the identified yeast throughout the fermentation process was studied, and Saccharomyces cerevisiae was found to be present mainly at the end of the fermentation process, while Aureobasidium pullulans was isolated primarily during the first days of fermentation in three of the eight spontaneous fermentations. This work highlights the complexity and diversity of the vineyard

  17. The ATM homologue MEC1 is required for phosphorylation of replication protein A in yeast

    International Nuclear Information System (INIS)

    Brush, G.S.; Morrow, D.M.; Hieter, P.; Kelly, T.J.

    1996-01-01

    Replication protein A (RPA) is a highly conserved single-stranded DNA-binding protein, required for cellular DNA replication, repair, and recombination. In human cells, RPA is phosphorylated during the S and G2 phases of the cell cycle and also in response to ionizing or ultraviolet radiation. Saccharomyces cerevisiae exhibits a similar pattern of cell cycle-regulated RPA phosphorylation, and our studies indicate that the radiation-induced reactions occur in yeast as well. We have examined yeast RPA phosphorylation during the normal cell cycle and in response to environmental insult, and have demonstrated that the checkpoint gene MEC1 is required for the reaction under all conditions tested. Through examination of several checkpoint mutants, we have placed RPA phosphorylation in a novel pathway of the DNA damage response. MEC1 is similar in sequence to human ATM, the gene mutated in patients with ataxia-telangiectasia (A-T). A-T cells are deficient in multiple checkpoint pathways and are hypersensitive to killing by ionizing radiation. Because A-T cells exhibit a delay in ionizing radiation-induced RPA phosphorylation, our results indicate a functional similarity between MEC1 and ATM, and suggest that RPA phosphorylation is involved in a conserved eukaryotic DNA damage-response pathway defective in A-T

  18. Spermine modulates fungal morphogenesis and activates plasma membrane H+-ATPase during yeast to hyphae transition

    Directory of Open Access Journals (Sweden)

    Antônio Jesus Dorighetto Cogo

    2018-02-01

    Full Text Available Polyamines play a regulatory role in eukaryotic cell growth and morphogenesis. Despite many molecular advances, the underlying mechanism of action remains unclear. Here, we investigate a mechanism by which spermine affects the morphogenesis of a dimorphic fungal model of emerging relevance in plant interactions, Yarrowia lipolytica, through the recruitment of a phytohormone-like pathway involving activation of the plasma membrane P-type H+-ATPase. Morphological transition was followed microscopically, and the H+-ATPase activity was analyzed in isolated membrane vesicles. Proton flux and acidification were directly probed at living cell surfaces by a non-invasive selective ion electrode technique. Spermine and indol-3-acetic acid (IAA induced the yeast-hypha transition, influencing the colony architecture. Spermine induced H+-ATPase activity and H+ efflux in living cells correlating with yeast-hypha dynamics. Pharmacological inhibition of spermine and IAA pathways prevented the physio-morphological responses, and indicated that spermine could act upstream of the IAA pathway. This study provides the first compelling evidence on the fungal morphogenesis and colony development as modulated by a spermine-induced acid growth mechanism analogous to that previously postulated for the multicellular growth regulation of plants.

  19. Game dynamic model for yeast development.

    Science.gov (United States)

    Huang, Yuanyuan; Wu, Zhijun

    2012-07-01

    Game theoretic models, along with replicator equations, have been applied successfully to the study of evolution of populations of competing species, including the growth of a population, the reaching of the population to an equilibrium state, and the evolutionary stability of the state. In this paper, we analyze a game model proposed by Gore et al. (Nature 456:253-256, 2009) in their recent study on the co-development of two mixed yeast strains. We examine the mathematical properties of this model with varying experimental parameters. We simulate the growths of the yeast strains and compare them with the experimental results. We also compute and analyze the equilibrium state of the system and prove that it is asymptotically and evolutionarily stable.

  20. Mapping replication origins in yeast chromosomes.

    Science.gov (United States)

    Brewer, B J; Fangman, W L

    1991-07-01

    The replicon hypothesis, first proposed in 1963 by Jacob and Brenner, states that DNA replication is controlled at sites called origins. Replication origins have been well studied in prokaryotes. However, the study of eukaryotic chromosomal origins has lagged behind, because until recently there has been no method for reliably determining the identity and location of origins from eukaryotic chromosomes. Here, we review a technique we developed with the yeast Saccharomyces cerevisiae that allows both the mapping of replication origins and an assessment of their activity. Two-dimensional agarose gel electrophoresis and Southern hybridization with total genomic DNA are used to determine whether a particular restriction fragment acquires the branched structure diagnostic of replication initiation. The technique has been used to localize origins in yeast chromosomes and assess their initiation efficiency. In some cases, origin activation is dependent upon the surrounding context. The technique is also being applied to a variety of eukaryotic organisms.

  1. [Invasive yeast infections in neutropenic patients].

    Science.gov (United States)

    Ruiz Camps, Isabel; Jarque, Isidro

    2016-01-01

    Invasive fungal diseases caused by yeasts still play an important role in the morbidity and mortality in neutropenic patients with haematological malignancies. Although the overall incidence of invasive candidiasis has decreased due to widespread use of antifungal prophylaxis, the incidence of non-Candida albicans Candida species is increasing compared with that of C.albicans, and mortality of invasive candidiasis continues to be high. In addition, there has been an increase in invasive infections caused by an array of uncommon yeasts, including species of the genus Malassezia, Rhodotorula, Trichosporon and Saprochaete, characterised by their resistance to echinocandins and poor prognosis. Copyright © 2016 Asociación Española de Micología. Publicado por Elsevier España, S.L.U. All rights reserved.

  2. Isolation and characterization of phenol degrading yeast.

    Science.gov (United States)

    Patel, Riddhi; Rajkumar, Shalini

    2009-04-01

    A phenol degrading yeast isolate was identified and characterized from the soil sample collected from a landfill site, in Ahmedabad, India, by plating the soil dilutions on Sabouraud's Dextrose Agar. The microscopic studies and biochemical tests indicated the isolate to be Saccharomyces cerevisiae. The phenol degrading potential of the isolate was measured by inoculation of pure culture in the mineral medium containing various phenol concentrations ranging from 100 to 800 mg l(-1 )and monitoring phenol disappearance rate at regular intervals of time. Growth of the isolate in mineral medium with various phenol concentrations was monitored by measuring the turbidity (OD(600) nm). The results showed that the isolated yeast was tolerant to phenol up to 800 mg(-1). The phenol degradation ranged from 8.57 to 100% for the concentration of phenol from 800 mg l(-1 )to 200 mg l(-1), respectively. ((c) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).

  3. Made for Each Other: Ascomycete Yeasts and Insects.

    Science.gov (United States)

    Blackwell, Meredith

    2017-06-01

    Fungi and insects live together in the same habitats, and many species of both groups rely on each other for success. Insects, the most successful animals on Earth, cannot produce sterols, essential vitamins, and many enzymes; fungi, often yeast-like in growth form, make up for these deficits. Fungi, however, require constantly replenished substrates because they consume the previous ones, and insects, sometimes lured by volatile fungal compounds, carry fungi directly to a similar, but fresh, habitat. Yeasts associated with insects include Ascomycota (Saccharomycotina, Pezizomycotina) and a few Basidiomycota. Beetles, homopterans, and flies are important associates of fungi, and in turn the insects carry yeasts in pits, specialized external pouches, and modified gut pockets. Some yeasts undergo sexual reproduction within the insect gut, where the genetic diversity of the population is increased, while others, well suited to their stable environment, may never mate. The range of interactions extends from dispersal of yeasts on the surface of insects (e.g., cactus- Drosophila -yeast and ephemeral flower communities, ambrosia beetles, yeasts with holdfasts) to extremely specialized associations of organisms that can no longer exist independently, as in the case of yeast-like symbionts of planthoppers. In a few cases yeast-like fungus-insect associations threaten butterflies and other species with extinction. Technical advances improve discovery and identification of the fungi but also inform our understanding of the evolution of yeast-insect symbioses, although there is much more to learn.

  4. High-throughput metabolic state analysis: The missing link in integrated functional genomics of yeasts

    DEFF Research Database (Denmark)

    Villas-Bôas, Silas Granato; Moxley, Joel. F; Åkesson, Mats Fredrik

    2005-01-01

    that achieve comparable throughput, effort and cost compared with DNA arrays. Our sample workup method enables simultaneous metabolite measurements throughout central carbon metabolism and amino acid biosynthesis, using a standard GC-MS platform that was optimized for this Purpose. As an implementation proof......-of-concept, we assayed metabolite levels in two yeast strains and two different environmental conditions in the context of metabolic pathway reconstruction. We demonstrate that these differential metabolite level data distinguish among sample types, such as typical metabolic fingerprinting or footprinting. More...

  5. How a Small Family of Yeast IDPs Control Complicated Processes Related to DNA Replication

    DEFF Research Database (Denmark)

    Marabini, Riccardo

    Ribonucleotide reductase (RNR) and proliferating cell nuclear antigen (PCNA) are two essential proteins involved in DNA replication. RNR catalyzes the last and rate limiting step of the deoxyribonucleotide biosynthetic pathway. The dysregulation of RNR has been related to higher mutation rate...... characterized in budding and fission yeast. Within this protein family Dif1 (from S. cerevisiae) and Spd1 (from S. pombe) were analyzed in this study. These proteins were previously found to interact with and regulate the activity of RNR and Spd1 was also linked to PCNA dependent signaling for degradation...

  6. MALDI-TOF MS as a tool to identify foodborne yeasts and yeast-like fungi.

    Science.gov (United States)

    Quintilla, Raquel; Kolecka, Anna; Casaregola, Serge; Daniel, Heide M; Houbraken, Jos; Kostrzewa, Markus; Boekhout, Teun; Groenewald, Marizeth

    2018-02-02

    Since food spoilage by yeasts causes high economic losses, fast and accurate identifications of yeasts associated with food and food-related products are important for the food industry. In this study the efficiency of the matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify food related yeasts was evaluated. A CBS in-house MALDI-TOF MS database was created and later challenged with a blinded test set of 146 yeast strains obtained from food and food related products. Ninety eight percent of the strains were correctly identified with log score values>1.7. One strain, Mrakia frigida, gained a correct identification with a score value1.7. Ambiguous identifications were observed due to two incorrect reference mass spectra's found in the commercial database BDAL v.4.0, namely Candida sake DSM 70763 which was re-identified as Candida oleophila, and Candida inconspicua DSM 70631 which was re-identified as Pichia membranifaciens. MALDI-TOF MS can distinguish between most of the species, but for some species complexes, such as the Kazachstania telluris and Mrakia frigida complexes, MALDI-TOF MS showed limited resolution and identification of sibling species was sometimes problematic. Despite this, we showed that the MALDI-TOF MS is applicable for routine identification and validation of foodborne yeasts, but a further update of the commercial reference databases is needed. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Phyllosphere yeasts rapidly break down biodegradable plastics

    OpenAIRE

    Kitamoto, Hiroko K; Shinozaki, Yukiko; Cao, Xiao-hong; Morita, Tomotake; Konishi, Masaaki; Tago, Kanako; Kajiwara, Hideyuki; Koitabashi, Motoo; Yoshida, Shigenobu; Watanabe, Takashi; Sameshima-Yamashita, Yuka; Nakajima-Kambe, Toshiaki; Tsushima, Seiya

    2011-01-01

    The use of biodegradable plastics can reduce the accumulation of environmentally persistent plastic wastes. The rate of degradation of biodegradable plastics depends on environmental conditions and is highly variable. Techniques for achieving more consistent degradation are needed. However, only a few microorganisms involved in the degradation process have been isolated so far from the environment. Here, we show that Pseudozyma spp. yeasts, which are common in the phyllosphere and are easily ...

  8. An engineered yeast efficiently secreting penicillin.

    Directory of Open Access Journals (Sweden)

    Loknath Gidijala

    Full Text Available This study aimed at developing an alternative host for the production of penicillin (PEN. As yet, the industrial production of this beta-lactam antibiotic is confined to the filamentous fungus Penicillium chrysogenum. As such, the yeast Hansenula polymorpha, a recognized producer of pharmaceuticals, represents an attractive alternative. Introduction of the P. chrysogenum gene encoding the non-ribosomal peptide synthetase (NRPS delta-(L-alpha-aminoadipyl-L-cysteinyl-D-valine synthetase (ACVS in H. polymorpha, resulted in the production of active ACVS enzyme, when co-expressed with the Bacillus subtilis sfp gene encoding a phosphopantetheinyl transferase that activated ACVS. This represents the first example of the functional expression of a non-ribosomal peptide synthetase in yeast. Co-expression with the P. chrysogenum genes encoding the cytosolic enzyme isopenicillin N synthase as well as the two peroxisomal enzymes isopenicillin N acyl transferase (IAT and phenylacetyl CoA ligase (PCL resulted in production of biologically active PEN, which was efficiently secreted. The amount of secreted PEN was similar to that produced by the original P. chrysogenum NRRL1951 strain (approx. 1 mg/L. PEN production was decreased over two-fold in a yeast strain lacking peroxisomes, indicating that the peroxisomal localization of IAT and PCL is important for efficient PEN production. The breakthroughs of this work enable exploration of new yeast-based cell factories for the production of (novel beta-lactam antibiotics as well as other natural and semi-synthetic peptides (e.g. immunosuppressive and cytostatic agents, whose production involves NRPS's.

  9. Environmental influences on organotin-yeast interactions

    OpenAIRE

    White, Jane S.

    2002-01-01

    As a consequence of the widespread industrial and agricultural applications of organotin compounds, contamination of various ecosystems has occurred in recent decades. Understanding how these compounds interact with cellular membranes is essential in assessing the risks of organotin pollution. The organotins, tributyltin (TBT) and trimethyltin (TMT) and inorganic tin, Sn(IV), were investigated for their physical interactions with non-metabolising cells and protoplasts of the yeast, Candida ma...

  10. Beneficial properties of probiotic yeast Saccharomyces boulardii

    OpenAIRE

    Tomičić Zorica M.; Čolović Radmilo R.; Čabarkapa Ivana S.; Vukmirović Đuro M.; Đuragić Olivera M.; Tomičić Ružica M.

    2016-01-01

    Saccharomyces boulardii is unique probiotic and biotherapeutic yeast, known to survive in gastric acidity and it is not adversely affected or inhibited by antibiotics or does not alter or adversely affect the normal microbiota. S. boulardii has been utilized worldwide as a probiotic supplement to support gastrointestinal health. The multiple mechanisms of action of S. boulardii and its properties may explain its efficacy and beneficial effects in acute and chronic gastrointestinal diseases th...

  11. Taxonomy Icon Data: fission yeast [Taxonomy Icon

    Lifescience Database Archive (English)

    Full Text Available fission yeast Schizosaccharomyces pombe Schizosaccharomyces_pombe_L.png Schizosaccharomyce...s_pombe_NL.png Schizosaccharomyces_pombe_S.png Schizosaccharomyces_pombe_NS.png http://biosciencedbc....jp/taxonomy_icon/icon.cgi?i=Schizosaccharomyces+pombe&t=L http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Schizosaccharomyce...s+pombe&t=NL http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Schizosaccharomyce...s+pombe&t=S http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Schizosaccharomyces+pombe&t=NS

  12. Pentose utilization in yeasts: Physiology and biochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Jeppson, H.

    1996-04-01

    The fermentive performance of bacteria, yeasts, and filamentous fungi was investigated in a pentose (xylose)-rich lignocellulosic hydrolyzate. The filamentous fungus Fusarium oxysporum and the xylose-fermenting yeast Pichia stipitis were found to be very sensitive to the inhibiting hydrolyzate. Recombinant xylose-utilizing Saccharomyces cerevisiae showed very poor ethanol formation from xylose; xylitol being the major product formed. The highest ethanol yields were obtained with recombinant Escherichia coli KO11, however, for maximal ethanol yield detoxification of the hydrolyzate was required. The influence of oxygen on the regulation of carbohydrate metabolism in the xylose-fermenting yeast P. stipitis CBS 6054 was investigated. A low and well-controlled level of oxygenation has been found to be required for efficient ethanol formation from xylose by the xylose-fermenting yeasts. The requirement of oxygen is frequently ascribed to the apparent redox imbalance which develops under anaerobic conditions due to the difference in co-factor utilization of the two first enzymes in the xylose metabolism, further reflected in xylitol excretion. However, a low and well controlled level of oxygenation for maximal ethanol production from glucose was also demonstrated, suggesting that the oxygen requirement is not only due to the dual co-factor utilization, but also serves other purposes. Cyanide-insensitive and salicyl hydroxamic acid-sensitive respiration (CIR) was found in P. stipitis. CIR is suggested to act as a redox sink preventing xylitol formation in P. stipitis under oxygen-limited xylose fermentations. Xylitol metabolism by P. stipitis CBS 6054 was strictly respiratory and ethanol was not formed under any conditions. The absence of ethanol formation was not due to a lack of fermentative enzymes, since the addition of glucose to xylitol-pregrown cells resulted in ethanol formation. 277 refs, 5 figs, 7 tabs

  13. Yeast Biodiversity from DOQ Priorat Uninoculated Fermentations

    OpenAIRE

    Padilla, Beatriz; Garc?a-Fern?ndez, David; Gonz?lez, Beatriz; Izidoro, Iara; Esteve-Zarzoso, Braulio; Beltran, Gemma; Mas, Albert

    2016-01-01

    Climate, soil, and grape varieties are the primary characteristics of terroir and lead to the definition of various appellations of origin. However, the microbiota associated with grapes are also affected by these conditions and can leave a footprint in a wine that will be part of the characteristics of terroir. Thus, a description of the yeast microbiota within a vineyard is of interest not only to provide a better understanding of the winemaking process, but also to understand the source of...

  14. Raman Microspectroscopy of the Yeast Vacuoles

    Czech Academy of Sciences Publication Activity Database

    Bednárová, Lucie; Palacký, J.; Bauerová, Václava; Hrušková-Heidingsfeldová, Olga; Pichová, Iva; Mojzeš, P.

    2012-01-01

    Roč. 27, 5-6 (2012), s. 503-507 ISSN 0712-4813 R&D Projects: GA ČR GAP208/10/0376; GA ČR GA310/09/1945 Institutional research plan: CEZ:AV0Z40550506 Keywords : Raman microspectroscopy * living cell * yeast * vacuole * chemical composition * polyphospate * Candida albicans Subject RIV: CE - Biochemistry Impact factor: 0.530, year: 2012

  15. Development of Industrial Yeast Platform Strains

    DEFF Research Database (Denmark)

    Bergdahl, Basti; Dato, Laura; Förster, Jochen

    2014-01-01

    Most of the current metabolic engineering projects are carried out using laboratory strains as the starting host. Although such strains are easily manipulated genetically, their robustness does not always meet the requirements set by industrial fermentation conditions. In such conditions, the cells...... screening of the 36 industrial and laboratory yeast strains. In addition, progress in the development of molecular biology methods for generating the new strains will be presented....

  16. Cyanohydrin reactions enhance glycolytic oscillations in yeast

    DEFF Research Database (Denmark)

    Hald, Bjørn Olav; Nielsen, Astrid Gram; Tortzen, Christian

    2015-01-01

    Synchronous metabolic oscillations can be induced in yeast by addition of glucose and removal of extracellular acetaldehyde (ACAx). Compared to other means of ACAx removal, cyanide robustly induces oscillations, indicating additional cyanide reactions besides ACA to lactonitrile conversion. Here......: a) by reducing [ACAx] relative to oscillation amplitude, b) by targeting multiple intracellular carbonyl compounds during fermentation, and c) by acting as a phase resetting stimulus....

  17. Enzymes of Candida tropicalis yeast biodegrading phenol

    OpenAIRE

    Koubková, Zuzana

    2011-01-01

    Effluents of industrial wastewaters from oil refineries, paper mills, dyes, ceramic factories, resins, textiles and plastic contain high concentrations of aromatic compounds, which are toxic to organisms. Degradation of these compounds to tolerant limits before releasing them into the environment is an urgent requirement. Candida tropicalis yeast is an important representative of eucaryotic microorganisms that are able to utilize phenol. During the first phase of phenol biodegradation, cytopl...

  18. Biotechnology of non-Saccharomyces yeasts-the basidiomycetes.

    Science.gov (United States)

    Johnson, Eric A

    2013-09-01

    Yeasts are the major producer of biotechnology products worldwide, exceeding production in capacity and economic revenues of other groups of industrial microorganisms. Yeasts have wide-ranging fundamental and industrial importance in scientific, food, medical, and agricultural disciplines (Fig. 1). Saccharomyces is the most important genus of yeast from fundamental and applied perspectives and has been expansively studied. Non-Saccharomyces yeasts (non-conventional yeasts) including members of the Ascomycetes and Basidiomycetes also have substantial current utility and potential applicability in biotechnology. In an earlier mini-review, "Biotechnology of non-Saccharomyces yeasts-the ascomycetes" (Johnson Appl Microb Biotechnol 97: 503-517, 2013), the extensive biotechnological utility and potential of ascomycetous yeasts are described. Ascomycetous yeasts are particularly important in food and ethanol formation, production of single-cell protein, feeds and fodder, heterologous production of proteins and enzymes, and as model and fundamental organisms for the delineation of genes and their function in mammalian and human metabolism and disease processes. In contrast, the roles of basidiomycetous yeasts in biotechnology have mainly been evaluated only in the past few decades and compared to the ascomycetous yeasts and currently have limited industrial utility. From a biotechnology perspective, the basidiomycetous yeasts are known mainly for the production of enzymes used in pharmaceutical and chemical synthesis, for production of certain classes of primary and secondary metabolites such as terpenoids and carotenoids, for aerobic catabolism of complex carbon sources, and for bioremediation of environmental pollutants and xenotoxicants. Notwithstanding, the basidiomycetous yeasts appear to have considerable potential in biotechnology owing to their catabolic utilities, formation of enzymes acting on recalcitrant substrates, and through the production of unique primary

  19. In situ rheology of yeast biofilms.

    Science.gov (United States)

    Brugnoni, Lorena I; Tarifa, María C; Lozano, Jorge E; Genovese, Diego

    2014-01-01

    The aim of the present work was to investigate the in situ rheological behavior of yeast biofilms growing on stainless steel under static and turbulent flow. The species used (Rhodototula mucilaginosa, Candida krusei, Candida kefyr and Candida tropicalis) were isolated from a clarified apple juice industry. The flow conditions impacted biofilm composition over time, with a predominance of C. krusei under static and turbulent flow. Likewise, structural variations occurred, with a tighter appearance under dynamic flow. Under turbulent flow there was an increase of 112 μm in biofilm thickness at 11 weeks (p < 0.001) and cell morphology was governed by hyphal structures and rounded cells. Using the in situ growth method introduced here, yeast biofilms were determined to be viscoelastic materials with a predominantly solid-like behavior, and neither this nor the G'0 values were significantly affected by the flow conditions or the growth time, and at large deformations their weak structure collapsed beyond a critical strain of about 1.5-5%. The present work could represent a starting point for developing in situ measurements of yeast rheology and contribute to a thin body of knowledge about fungal biofilm formation.

  20. Determination of Proteinaceous Selenocysteine in Selenized Yeast

    Directory of Open Access Journals (Sweden)

    Katarzyna Bierla

    2018-02-01

    Full Text Available A method for the quantitation of proteinaceous selenocysteine (SeCys in Se-rich yeast was developed. The method is based on the reduction of the Se-Se and S-Se bridges with dithiotretiol, derivatization with iodoacetamide (carbamidomethylation, followed by HPLC-ICP MS. The chromatographic conditions were optimized for the total recovery of the proteinaceous selenocysteine, the minimum number of peaks in the chromatogram (reduction of derivatization products of other Se-species present and the baseline separation. A typical chromatogram of a proteolytic digest of selenized yeast protein consisted of up to five peaks (including SeMet, carbamidomethylated (CAM-SeCys, and Se(CAM2 identified by retention time matching with available standards and electrospray MS. Inorganic selenium non-specifically attached to proteins and selenomethionine could be quantified (in the form of Se(CAM2 along with SeCys. Selenocysteine, selenomethionine, inorganic selenium, and the water soluble-metabolite fraction accounted for the totality of selenium species in Se-rich yeast.

  1. How do yeast sense mitochondrial dysfunction?

    Directory of Open Access Journals (Sweden)

    Dmitry A. Knorre

    2016-09-01

    Full Text Available Apart from energy transformation, mitochondria play important signaling roles. In yeast, mitochondrial signaling relies on several molecular cascades. However, it is not clear how a cell detects a particular mitochondrial malfunction. The problem is that there are many possible manifestations of mitochondrial dysfunction. For example, exposure to the specific antibiotics can either decrease (inhibitors of respiratory chain or increase (inhibitors of ATP-synthase mitochondrial transmembrane potential. Moreover, even in the absence of the dysfunctions, a cell needs feedback from mitochondria to coordinate mitochondrial biogenesis and/or removal by mitophagy during the division cycle. To cope with the complexity, only a limited set of compounds is monitored by yeast cells to estimate mitochondrial functionality. The known examples of such compounds are ATP, reactive oxygen species, intermediates of amino acids synthesis, short peptides, Fe-S clusters and heme, and also the precursor proteins which fail to be imported by mitochondria. On one hand, the levels of these molecules depend not only on mitochondria. On the other hand, these substances are recognized by the cytosolic sensors which transmit the signals to the nucleus leading to general, as opposed to mitochondria-specific, transcriptional response. Therefore, we argue that both ways of mitochondria-to-nucleus communication in yeast are mostly (if not completely unspecific, are mediated by the cytosolic signaling machinery and strongly depend on cellular metabolic state.

  2. [Mitochondria inheritance in yeast saccharomyces cerevisiae].

    Science.gov (United States)

    Fizikova, A Iu

    2011-01-01

    The review is devoted to the main mechanisms of mitochondria inheritance in yeast Saccharonmyces cerevisiae. The genetic mechanisms of functionally active mitochondria inheritance in eukaryotic cells is one of the most relevant in modem researches. A great number of genetic diseases are associated with mitochondria dysfunction. Plasticity of eukaryotic cell metabolism according to the environmental changes is ensured by adequate mitochondria functioning by means of ATP synthesis coordination, reactive oxygen species accumulation, apoptosis regulation and is an important factor of cell adaptation to stress. Mitochondria participation in important for cell vitality processes masters the presence of accurate mechanisms of mitochondria functions regulation according to environment fluctuations. The mechanisms of mitochondria division and distribution are highly conserved. Baker yeast S. cerevisiae is an ideal model object for mitochondria researches due to energetic metabolism lability, ability to switch over respiration to fermentation, and petite-positive phenotype. Correction of metabolism according to the environmental changes is necessary for cell vitality. The influence of respiratory, carbon, amino acid and phosphate metabolism on mitochondria functions was shown. As far as the mechanisms that stabilize functions of mitochondria and mtDNA are highly conserve, we can project yeast regularities on higher eukaryotes systems. This makes it possible to approximate understanding the etiology and pathogenesis of a great number of human diseases.

  3. HAA1 and PRS3 overexpression boosts yeast tolerance towards acetic acid improving xylose or glucose consumption: unravelling the underlying mechanisms.

    Science.gov (United States)

    Cunha, Joana T; Costa, Carlos E; Ferraz, Luís; Romaní, Aloia; Johansson, Björn; Sá-Correia, Isabel; Domingues, Lucília

    2018-04-02

    Acetic acid tolerance and xylose consumption are desirable traits for yeast strains used in industrial biotechnological processes. In this work, overexpression of a weak acid stress transcriptional activator encoded by the gene HAA1 and a phosphoribosyl pyrophosphate synthetase encoded by PRS3 in a recombinant industrial Saccharomyces cerevisiae strain containing a xylose metabolic pathway was evaluated in the presence of acetic acid in xylose- or glucose-containing media. HAA1 or PRS3 overexpression resulted in superior yeast growth and higher sugar consumption capacities in the presence of 4 g/L acetic acid, and a positive synergistic effect resulted from the simultaneous overexpression of both genes. Overexpressing these genes also improved yeast adaptation to a non-detoxified hardwood hydrolysate with a high acetic acid content. Furthermore, the overexpression of HAA1 and/or PRS3 was found to increase the robustness of yeast cell wall when challenged with acetic acid stress, suggesting the involvement of the modulation of the cell wall integrity pathway. This study clearly shows HAA1 and/or, for the first time, PRS3 overexpression to play an important role in the improvement of industrial yeast tolerance towards acetic acid. The results expand the molecular toolbox and add to the current understanding of the mechanisms involved in higher acetic acid tolerance, paving the way for the further development of more efficient industrial processes.

  4. Controlling Lipid Fluxes at Glycerol-3-phosphate Acyltransferase Step in Yeast

    Science.gov (United States)

    Marr, Nancy; Foglia, Julena; Terebiznik, Mauricio; Athenstaedt, Karin; Zaremberg, Vanina

    2012-01-01

    The ability to channel excess fatty acids into neutral lipids like triacylglycerol (TAG) is a critical strategy used by cells to maintain lipid homeostasis. Upon activation to acyl-CoA, fatty acids become readily available as substrates for acyltransferases involved in neutral lipid synthesis. Neutral lipids are then packed into organelles derived from the endoplasmic reticulum called lipid particles (LPs). The first acylation step in the de novo pathway for TAG synthesis is catalyzed by glycerol-3-phosphate acyltransferases (GPATs). Two isoforms, Gat1p/Gpt2p and Gat2p/Sct1p, are present in the yeast Saccharomyces cerevisiae. Previous evidence indicated that these enzymes contribute differentially to the synthesis of TAG in actively growing cells. In this work we studied the role of the yeast GPATs in the formation of LPs induced by a surplus of oleic acid. Yeast lacking Gat1p (but not Gat2p) were sensitive to oleate and failed to accumulate LPs induced by this unsaturated fatty acid. It is shown that oleate induces dephosphorylation of Gat1p as well as an increment in its levels. Most importantly, we identified novel Gat1p crescent structures that are formed in the presence of oleate. These structures are connected with the endoplasmic reticulum and are intimately associated with LPs. No such structures were observed for Gat2p. A crucial point of control of lipid fluxes at the GPAT step is proposed. PMID:22267742

  5. Supplementary Material for: Polyglutamine toxicity in yeast induces metabolic alterations and mitochondrial defects

    KAUST Repository

    Papsdorf, Katharina

    2015-01-01

    Abstract Background Protein aggregation and its pathological effects are the major cause of several neurodegenerative diseases. In Huntingtonâ s disease an elongated stretch of polyglutamines within the protein Huntingtin leads to increased aggregation propensity. This induces cellular defects, culminating in neuronal loss, but the connection between aggregation and toxicity remains to be established. Results To uncover cellular pathways relevant for intoxication we used genome-wide analyses in a yeast model system and identify fourteen genes that, if deleted, result in higher polyglutamine toxicity. Several of these genes, like UGO1, ATP15 and NFU1 encode mitochondrial proteins, implying that a challenged mitochondrial system may become dysfunctional during polyglutamine intoxication. We further employed microarrays to decipher the transcriptional response upon polyglutamine intoxication, which exposes an upregulation of genes involved in sulfur and iron metabolism and mitochondrial Fe-S cluster formation. Indeed, we find that in vivo iron concentrations are misbalanced and observe a reduction in the activity of the prominent Fe-S cluster containing protein aconitase. Like in other yeast strains with impaired mitochondria, non-fermentative growth is impossible after intoxication with the polyglutamine protein. NMR-based metabolic analyses reveal that mitochondrial metabolism is reduced, leading to accumulation of metabolic intermediates in polyglutamine-intoxicated cells. Conclusion These data show that damages to the mitochondrial system occur in polyglutamine intoxicated yeast cells and suggest an intricate connection between polyglutamine-induced toxicity, mitochondrial functionality and iron homeostasis in this model system.

  6. A nutrient dependant switch explains mutually exclusive existence of meiosis and mitosis initiation in budding yeast.

    Science.gov (United States)

    Wannige, C T; Kulasiri, D; Samarasinghe, S

    2014-01-21

    Nutrients from living environment are vital for the survival and growth of any organism. Budding yeast diploid cells decide to grow by mitosis type cell division or decide to create unique, stress resistant spores by meiosis type cell division depending on the available nutrient conditions. To gain a molecular systems level understanding of the nutrient dependant switching between meiosis and mitosis initiation in diploid cells of budding yeast, we develop a theoretical model based on ordinary differential equations (ODEs) including the mitosis initiator and its relations to budding yeast meiosis initiation network. Our model accurately and qualitatively predicts the experimentally revealed temporal variations of related proteins under different nutrient conditions as well as the diverse mutant studies related to meiosis and mitosis initiation. Using this model, we show how the meiosis and mitosis initiators form an all-or-none type bistable switch in response to available nutrient level (mainly nitrogen). The transitions to and from meiosis or mitosis initiation states occur via saddle node bifurcation. This bidirectional switch helps the optimal usage of available nutrients and explains the mutually exclusive existence of meiosis and mitosis pathways. © 2013 Elsevier Ltd. All rights reserved.

  7. Aggregation and retention of human urokinase type plasminogen activator in the yeast endoplasmic reticulum

    Directory of Open Access Journals (Sweden)

    Smirnov Vladimir N

    2002-10-01

    Full Text Available Abstract Background Secretion of recombinant proteins in yeast can be affected by their improper folding in the endoplasmic reticulum and subsequent elimination of the misfolded molecules via the endoplasmic reticulum associated protein degradation pathway. Recombinant proteins can also be degraded by the vacuolar protease complex. Human urokinase type plasminogen activator (uPA is poorly secreted by yeast but the mechanisms interfering with its secretion are largely unknown. Results We show that in Hansenula polymorpha overexpression worsens uPA secretion and stimulates its intracellular aggregation. The absence of the Golgi modifications in accumulated uPA suggests that aggregation occurs within the endoplasmic reticulum. Deletion analysis has shown that the N-terminal domains were responsible for poor uPA secretion and propensity to aggregate. Mutation abolishing N-glycosylation decreased the efficiency of uPA secretion and increased its aggregation degree. Retention of uPA in the endoplasmic reticulum stimulates its aggregation. Conclusions The data obtained demonstrate that defect of uPA secretion in yeast is related to its retention in the endoplasmic reticulum. Accumulation of uPA within the endoplasmic reticulum disturbs its proper folding and leads to formation of high molecular weight aggregates.

  8. Squalene epoxidase as a target for manipulation of squalene levels in the yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    Garaiová, Martina; Zambojová, Veronika; Simová, Zuzana; Griač, Peter; Hapala, Ivan

    2014-03-01

    Squalene is a valuable natural substance with several biotechnological applications. In the yeast Saccharomyces cerevisiae, it is produced in the isoprenoid pathway as the first precursor dedicated to ergosterol biosynthesis. The aim of this study was to explore the potential of squalene epoxidase encoded by the ERG1 gene as the target for manipulating squalene levels in yeast. Highest squalene levels (over 1000 μg squalene per 10(9)  cells) were induced by specific point mutations in ERG1 gene that reduced activity of squalene epoxidase and caused hypersensitivity to terbinafine. This accumulation of squalene in erg1 mutants did not significantly disturb their growth. Treatment with squalene epoxidase inhibitor terbinafine revealed a limit in squalene accumulation at 700 μg squalene per 10(9)  cells which was associated with pronounced growth defects. Inhibition of squalene epoxidase activity by anaerobiosis or heme deficiency resulted in relatively low squalene levels. These levels were significantly increased by ergosterol depletion in anaerobic cells which indicated feedback inhibition of squalene production by ergosterol. Accumulation of squalene in erg1 mutants and terbinafine-treated cells were associated with increased cellular content and aggregation of lipid droplets. Our results prove that targeted genetic manipulation of the ERG1 gene is a promising tool for increasing squalene production in yeast. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd.

  9. [Intragenic mitotic recombination induced by ultraviolet and gamma rays in radiosensitive mutants of Saccharomyces cerevisiae yeasts].

    Science.gov (United States)

    Zakharov, I A; Kasinova, G V; Koval'tsova, S V

    1983-01-01

    The effect of UV- and gamma-irradiation on the survival and intragenic mitotic recombination (gene conversion) of 5 radiosensitive mutants was studied in comparison with the wild type. The level of spontaneous conversion was similar for RAD, rad2 and rad15, mutations xrs2 and xrs4 increasing and rad54 significantly decreasing it. The frequency of conversion induced by UV-light was greater in rad2, rad15 and xrs2 mutants and lower in xrs4, as compared to RAD. Gamma-irradiation caused induction of gene conversion with an equal frequency in RAD, rad2, rad15. Xrs2 and xrs4 mutations slightly decreased gamma-induced conversion. In rad54 mutant, UV-and gamma-induced conversion was practically absent. In the wild type yeast, a diploid strain is more resistant than a haploid, whereas in rad54 a diploid strain has the same or an increased sensitivity, as compared to a haploid strain (the "inverse ploidy effect"). This effect and also the block of induced mitotic recombination caused by rad54 indicate the presence in the yeast Saccharomyces cerevisiae of repair pathways of UV- and gamma-induced damages acting in diploid cells and realised by recombination. The data obtained as a result of many years' investigation of genetic effects in radiosensitive mutants of yeast are summarised and considered.

  10. Bayesian modeling of the yeast SH3 domain interactome predicts spatiotemporal dynamics of endocytosis proteins.

    Directory of Open Access Journals (Sweden)

    Raffi Tonikian

    2009-10-01

    Full Text Available SH3 domains are peptide recognition modules that mediate the assembly of diverse biological complexes. We scanned billions of phage-displayed peptides to map the binding specificities of the SH3 domain family in the budding yeast, Saccharomyces cerevisiae. Although most of the SH3 domains fall into the canonical classes I and II, each domain utilizes distinct features of its cognate ligands to achieve binding selectivity. Furthermore, we uncovered several SH3 domains with specificity profiles that clearly deviate from the two canonical classes. In conjunction with phage display, we used yeast two-hybrid and peptide array screening to independently identify SH3 domain binding partners. The results from the three complementary techniques were integrated using a Bayesian algorithm to generate a high-confidence yeast SH3 domain interaction map. The interaction map was enriched for proteins involved in endocytosis, revealing a set of SH3-mediated interactions that underlie formation of protein complexes essential to this biological pathway. We used the SH3 domain interaction network to predict the dynamic localization of several previously uncharacterized endocytic proteins, and our analysis suggests a novel role for the SH3 domains of Lsb3p and Lsb4p as hubs that recruit and assemble several endocytic complexes.

  11. A Yeast Mutant Deleted of GPH1 Bears Defects in Lipid Metabolism.

    Directory of Open Access Journals (Sweden)

    Martina Gsell

    Full Text Available In a previous study we demonstrated up-regulation of the yeast GPH1 gene under conditions of phosphatidylethanolamine (PE depletion caused by deletion of the mitochondrial (M phosphatidylserine decarboxylase 1 (PSD1 (Gsell et al., 2013, PLoS One. 8(10:e77380. doi: 10.1371/journal.pone.0077380. Gph1p has originally been identified as a glycogen phosphorylase catalyzing degradation of glycogen to glucose in the stationary growth phase of the yeast. Here we show that deletion of this gene also causes decreased levels of phosphatidylcholine (PC, triacylglycerols and steryl esters. Depletion of the two non-polar lipids in a Δgph1 strain leads to lack of lipid droplets, and decrease of the PC level results in instability of the plasma membrane. In vivo labeling experiments revealed that formation of PC via both pathways of biosynthesis, the cytidine diphosphate (CDP-choline and the methylation route, is negatively affected by a Δgph1 mutation, although expression of genes involved is not down regulated. Altogether, Gph1p besides its function as a glycogen mobilizing enzyme appears to play a regulatory role in yeast lipid metabolism.

  12. Identification of drug targets by chemogenomic and metabolomic profiling in yeast

    KAUST Repository

    Wu, Manhong

    2012-12-01

    OBJECTIVE: To advance our understanding of disease biology, the characterization of the molecular target for clinically proven or new drugs is very important. Because of its simplicity and the availability of strains with individual deletions in all of its genes, chemogenomic profiling in yeast has been used to identify drug targets. As measurement of drug-induced changes in cellular metabolites can yield considerable information about the effects of a drug, we investigated whether combining chemogenomic and metabolomic profiling in yeast could improve the characterization of drug targets. BASIC METHODS: We used chemogenomic and metabolomic profiling in yeast to characterize the target for five drugs acting on two biologically important pathways. A novel computational method that uses a curated metabolic network was also developed, and it was used to identify the genes that are likely to be responsible for the metabolomic differences found. RESULTS AND CONCLUSION: The combination of metabolomic and chemogenomic profiling, along with data analyses carried out using a novel computational method, could robustly identify the enzymes targeted by five drugs. Moreover, this novel computational method has the potential to identify genes that are causative of metabolomic differences or drug targets. © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins.

  13. Biomedical applications of yeast- a patent view, part one: yeasts as workhorses for the production of therapeutics and vaccines.

    Science.gov (United States)

    Roohvand, Farzin; Shokri, Mehdi; Abdollahpour-Alitappeh, Meghdad; Ehsani, Parastoo

    2017-08-01

    Yeasts, as Eukaryotes, offer unique features for ease of growth and genetic manipulation possibilities, making it an exceptional microbial host. Areas covered: This review provides general and patent-oriented insights into production of biopharmaceuticals by yeasts. Patents, wherever possible, were correlated to the original or review articles. The review describes applications of major GRAS (generally regarded as safe) yeasts for the production of therapeutic proteins and subunit vaccines; additionally, immunomodulatory properties of yeast cell wall components were reviewed for use of whole yeast cells as a new vaccine platform. The second part of the review will discuss yeast- humanization strategies and innovative applications. Expert opinion: Biomedical applications of yeasts were initiated by utilization of Saccharomyces cerevisiae, for production of leavened (fermented) products, and advanced to serve to produce biopharmaceuticals. Higher biomass production and expression/secretion yields, more similarity of glycosylation patterns to mammals and possibility of host-improvement strategies through application of synthetic biology might enhance selection of Pichia pastoris (instead of S. cerevisiae) as a host for production of biopharmaceutical in future. Immunomodulatory properties of yeast cell wall β-glucans and possibility of intracellular expression of heterologous pathogen/tumor antigens in yeast cells have expanded their application as a new platform, 'Whole Yeast Vaccines'.

  14. Biodegradation of lindane using a novel yeast strain, Rhodotorula sp. VITJzN03 isolated from agricultural soil.

    Science.gov (United States)

    Abdul Salam, Jaseetha; Lakshmi, V; Das, Devlina; Das, Nilanjana

    2013-03-01

    Lindane is a notorious organochlorine pesticide due to its high toxicity, persistence in the environment and its tendency to bioaccumulate. A yeast strain isolated from sorghum cultivation field was able to use lindane as carbon and energy source under aerobic conditions. With molecular techniques, it was identified and named as Rhodotorula strain VITJzN03. The effects of nutritional and environmental factors on yeast growth and the biodegradation of lindane was investigated. The maximum production of yeast biomass along with 100 % lindane mineralization was noted at an initial lindane concentration of 600 mg l(-1) within a period of 10 days. Lindane concentration above 600 mg l(-1) inhibited the growth of yeast in liquid medium. A positive relationship was noted between the release of chloride ions and the increase of yeast biomass as well as degradation of lindane. The calculated degradation rate and half life of lindane were found to be 0.416 day(-1) and 1.66 days, respectively. The analysis of the metabolites using GC-MS identified the formation of seven intermediates including γ-pentachlorocyclohexane(γ-PCCH), 1,3,4,6-tetrachloro-1,4-cyclohexadiene(1,4-TCCHdiene), 1,2,4-trichlorobenzene (1,2,4 TCB), 1,4-dichlorobenzene (1,4 DCB), chloro-cis-1,2-dihydroxycyclohexadiene (CDCHdiene), 3-chlorocatechol (3-CC) and maleylacetate (MA) derivatives indicating that lindane degradation follows successive dechlorination and oxido-reduction. Based on the results of the present study, the possible pathway for lindane degradation by Rhodotorula sp. VITJzN03 has been proposed. To the best of our knowledge, this is the first report on lindane degradation by yeast which can serve as a potential agent for in situ bioremediation of medium to high level lindane-contaminated sites.

  15. Taming wild yeast: potential of conventional and nonconventional yeasts in industrial fermentations.

    Science.gov (United States)

    Steensels, Jan; Verstrepen, Kevin J

    2014-01-01

    Yeasts are the main driving force behind several industrial food fermentation processes, including the production of beer, wine, sake, bread, and chocolate. Historically, these processes developed from uncontrolled, spontaneous fermentation reactions that rely on a complex mixture of microbes present in the environment. Because such spontaneous processes are generally inconsistent and inefficient and often lead to the formation of off-flavors, most of today's industrial production utilizes defined starter cultures, often consisting of a specific domesticated strain of Saccharomyces cerevisiae, S. bayanus, or S. pastorianus. Although this practice greatly improved process consistency, efficiency, and overall quality, it also limited the sensorial complexity of the end product. In this review, we discuss how Saccharomyces yeasts were domesticated to become the main workhorse of food fermentations, and we investigate the potential and selection of nonconventional yeasts that are often found in spontaneous fermentations, such as Brettanomyces, Hanseniaspora, and Pichia spp.

  16. Regulation of NAD+ metabolism, signaling and compartmentalization in the yeast Saccharomyces cerevisiae

    Science.gov (United States)

    Kato, Michiko; Lin, Su-Ju

    2014-01-01

    Pyridine nucleotides are essential coenzymes in many cellular redox reactions in all living systems. In addition to functioning as a redox carrier, NAD+ is also a required co-substrate for the conserved sirtuin deacetylases. Sirtuins regulate transcription, genome maintenance and metabolism and function as molecular links between cells and their environment. Maintaining NAD+ homeostasis is essential for proper cellular function and aberrant NAD+ metabolism has been implicated in a number of metabolic- and age-associated diseases. Recently, NAD+ metabolism has been linked to the phosphate-responsive signaling pathway (PHO pathway) in the budding yeast Saccharomyces cerevisiae. Activation of the PHO pathway is associated with the production and mobilization of the NAD+ metabolite nicotinamide riboside (NR), which is mediated in part by PHO-regulated nucleotidases. Cross-regulation between NAD+ metabolism and the PHO pathway has also been reported; however, detailed mechanisms remain to be elucidated. The PHO pathway also appears to modulate the activities of common downstream effectors of multiple nutrient-sensing pathways (Ras-PKA, TOR, Sch9/AKT). These signaling pathways were suggested to play a role in calorie restriction-mediated beneficial effects, which have also been linked to Sir2 function and NAD+ metabolism. Here, we discuss the interactions of these pathways and their potential roles in regulating NAD+ metabolism. In eukaryotic cells, intracellular compartmentalization facilitates the regulation of enzymatic functions and also concentrates or sequesters specific metabolites. Various NAD+-mediated cellular functions such as mitochondrial oxidative phosphorylation are compartmentalized. Therefore, we also discuss several key players functioning in mitochondrial, cytosolic and vacuolar compartmentalization of NAD+ intermediates, and their potential roles in NAD+ homeostasis. To date, it remains unclear how NAD+ and NAD+ intermediates shuttle between different

  17. Regulation of NAD+ metabolism, signaling and compartmentalization in the yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    Kato, Michiko; Lin, Su-Ju

    2014-11-01

    Pyridine nucleotides are essential coenzymes in many cellular redox reactions in all living systems. In addition to functioning as a redox carrier, NAD(+) is also a required co-substrate for the conserved sirtuin deacetylases. Sirtuins regulate transcription, genome maintenance and metabolism and function as molecular links between cells and their environment. Maintaining NAD(+) homeostasis is essential for proper cellular function and aberrant NAD(+) metabolism has been implicated in a number of metabolic- and age-associated diseases. Recently, NAD(+) metabolism has been linked to the phosphate-responsive signaling pathway (PHO pathway) in the budding yeast Saccharomyces cerevisiae. Activation of the PHO pathway is associated with the production and mobilization of the NAD(+) metabolite nicotinamide riboside (NR), which is mediated in part by PHO-regulated nucleotidases. Cross-regulation between NAD(+) metabolism and the PHO pathway has also been reported; however, detailed mechanisms remain to be elucidated. The PHO pathway also appears to modulate the activities of common downstream effectors of multiple nutrient-sensing pathways (Ras-PKA, TOR, Sch9/AKT). These signaling pathways were suggested to play a role in calorie restriction-mediated beneficial effects, which have also been linked to Sir2 function and NAD(+) metabolism. Here, we discuss the interactions of these pathways and their potential roles in regulating NAD(+) metabolism. In eukaryotic cells, intracellular compartmentalization facilitates the regulation of enzymatic functions and also concentrates or sequesters specific metabolites. Various NAD(+)-mediated cellular functions such as mitochondrial oxidative phosphorylation are compartmentalized. Therefore, we also discuss several key players functioning in mitochondrial, cytosolic and vacuolar compartmentalization of NAD(+) intermediates, and their potential roles in NAD(+) homeostasis. To date, it remains unclear how NAD(+) and NAD(+) intermediates

  18. Not your ordinary yeast: non-Saccharomyces yeasts in wine production uncovered.

    Science.gov (United States)

    Jolly, Neil P; Varela, Cristian; Pretorius, Isak S

    2014-03-01

    Saccharomyces cerevisiae and grape juice are 'natural companions' and make a happy wine marriage. However, this relationship can be enriched by allowing 'wild' non-Saccharomyces yeast to participate in a sequential manner in the early phases of grape must fermentation. However, such a triangular relationship is complex and can only be taken to 'the next level' if there are no spoilage yeast present and if the 'wine yeast' - S. cerevisiae - is able to exert its dominance in time to successfully complete the alcoholic fermentation. Winemakers apply various 'matchmaking' strategies (e.g. cellar hygiene, pH, SO2 , temperature and nutrient management) to keep 'spoilers' (e.g. Dekkera bruxellensis) at bay, and allow 'compatible' wild yeast (e.g. Torulaspora delbrueckii, Pichia kluyveri, Lachancea thermotolerans and Candida/Metschnikowia pulcherrima) to harmonize with potent S. cerevisiae wine yeast and bring the best out in wine. Mismatching can lead to a 'two is company, three is a crowd' scenario. More than 40 of the 1500 known yeast species have been isolated from grape must. In this article, we review the specific flavour-active characteristics of those non-Saccharomyces species that might play a positive role in both spontaneous and inoculated wine ferments. We seek to present 'single-species' and 'multi-species' ferments in a new light and a new context, and we raise important questions about the direction of mixed-fermentation research to address market trends regarding so-called 'natural' wines. This review also highlights that, despite the fact that most frontier research and technological developments are often focussed primarily on S. cerevisiae, non-Saccharomyces research can benefit from the techniques and knowledge developed by research on the former. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  19. Black yeast-like fungi in skin and nail

    DEFF Research Database (Denmark)

    Saunte, D M; Tarazooie, B; Arendrup, M C

    2011-01-01

    Black yeast-like fungi are rarely reported from superficial infections. We noticed a consistent prevalence of these organisms as single isolations from mycological routine specimens. To investigate the prevalence of black yeast-like fungi in skin, hair and nail specimens and to discuss...... the probability of these species to be involved in disease. Slow-growing black yeast-like fungi in routine specimens were prospectively collected and identified. A questionnaire regarding patient information was sent to physicians regarding black yeast-like fungus positive patients. A total of 20 746...... dermatological specimens were examined by culture. Black yeast-like fungi accounted for 2.2% (n = 108) of the positive cultures. Only 31.0% of the samples, culture positive for black yeast-like fungi were direct microscopy positive when compared with overall 68.8% of the culture positive specimens. The most...

  20. Yeast Genomics for Bread, Beer, Biology, Bucks and Breath

    Science.gov (United States)

    Sakharkar, Kishore R.; Sakharkar, Meena K.

    The rapid advances and scale up of projects in DNA sequencing dur ing the past two decades have produced complete genome sequences of several eukaryotic species. The versatile genetic malleability of the yeast, and the high degree of conservation between its cellular processes and those of human cells have made it a model of choice for pioneering research in molecular and cell biology. The complete sequence of yeast genome has proven to be extremely useful as a reference towards the sequences of human and for providing systems to explore key gene functions. Yeast has been a ‘legendary model’ for new technologies and gaining new biological insights into basic biological sciences and biotechnology. This chapter describes the awesome power of yeast genetics, genomics and proteomics in understanding of biological function. The applications of yeast as a screening tool to the field of drug discovery and development are highlighted and the traditional importance of yeast for bakers and brewers is discussed.

  1. A new methodology to obtain wine yeast strains overproducing mannoproteins.

    Science.gov (United States)

    Quirós, Manuel; Gonzalez-Ramos, Daniel; Tabera, Laura; Gonzalez, Ramon

    2010-04-30

    Yeast mannoproteins are highly glycosylated proteins that are covalently bound to the beta-1,3-glucan present in the yeast cell wall. Among their outstanding enological properties, yeast mannoproteins contribute to several aspects of wine quality by protecting against protein haze, reducing astringency, retaining aroma compounds and stimulating growth of lactic-acid bacteria. The development of a non-recombinant method to obtain enological yeast strains overproducing mannoproteins would therefore be very useful. Our previous experience on the genetic determinants of the release of these molecules by Saccharomyces cerevisiae has allowed us to propose a new methodology to isolate and characterize wine yeast that overproduce mannoproteins. The described methodology is based on the resistance of the killer 9 toxin produced by Williopsis saturnus, a feature linked to an altered biogenesis of the yeast cell wall. Copyright 2010 Elsevier B.V. All rights reserved.

  2. Yeast hulls: effect on spontaneous fermentation in different vinification conditions

    Directory of Open Access Journals (Sweden)

    Rosa López

    2000-09-01

    Full Text Available The effect of the addition of yeast hulls in vinification was investigated during three consecutive years. The study was carried out in the experimental winery of C.I.D.A in La Rioja (Spain with free running white grape juice of the Viura variety. Four different vinifications were studied. In two of these vinifications, stuck fermentations were detected. In all the studies, the addition of yeast hulls (yeast ghosts improved the fermentation kinetics, increasing the number of viable yeasts at the end of the exponential stage and decreasing the final content of reducing sugars. This work revealed a new effect of yeast hull addition which had not been identified previously; their selection effect on the wild yeast strain in spontaneous fermentation.

  3. Pathway Distiller - multisource biological pathway consolidation.

    Science.gov (United States)

    Doderer, Mark S; Anguiano, Zachry; Suresh, Uthra; Dashnamoorthy, Ravi; Bishop, Alexander J R; Chen, Yidong

    2012-01-01

    One method to understand and evaluate an experiment that produces a large set of genes, such as a gene expression microarray analysis, is to identify overrepresentation or enrichment for biological pathways. Because pathways are able to functionally describe the set of genes, much effort has been made to collect curated biological pathways into publicly accessible databases. When combining disparate databases, highly related or redundant pathways exist, making their consolidation into pathway concepts essential. This will facilitate unbiased, comprehensive yet streamlined analysis of experiments that result in large gene sets. After gene set enrichment finds representative pathways for large gene sets, pathways are consolidated into representative pathway concepts. Three complementary, but different methods of pathway consolidation are explored. Enrichment Consolidation combines the set of the pathways enriched for the signature gene list through iterative combining of enriched pathways with other pathways with similar signature gene sets; Weighted Consolidation utilizes a Protein-Protein Interaction network based gene-weighting approach that finds clusters of both enriched and non-enriched pathways limited to the experiments' resultant gene list; and finally the de novo Consolidation method uses several measurements of pathway similarity, that finds static pathway clusters independent of any given experiment. We demonstrate that the three consolidation methods provide unified yet different functional insights of a resultant gene set derived from a genome-wide profiling experiment. Results from the methods are presented, demonstrating their applications in biological studies and comparing with a pathway web-based framework that also combines several pathway databases. Additionally a web-based consolidation framework that encompasses all three methods discussed in this paper, Pathway Distiller (http://cbbiweb.uthscsa.edu/PathwayDistiller), is established to allow

  4. Isolation and characterization of awamori yeast mutants with L-leucine accumulation that overproduce isoamyl alcohol.

    Science.gov (United States)

    Takagi, Hiroshi; Hashida, Keisuke; Watanabe, Daisuke; Nasuno, Ryo; Ohashi, Masataka; Iha, Tomoya; Nezuo, Maiko; Tsukahara, Masatoshi

    2015-02-01

    Awamori shochu is a traditional distilled alcoholic beverage made from steamed rice in Okinawa, Japan. Although it has a unique aroma that is distinguishable from that of other types of shochu, no studies have been reported on the breeding of awamori yeasts. In yeast, isoamyl alcohol (i-AmOH), known as the key flavor of bread, is mainly produced from α-ketoisocaproate in the pathway of L-leucine biosynthesis, which is regulated by end-product inhibition of α-isopropylmalate synthase (IPMS). Here, we isolated mutants resistant to the L-leucine analog 5,5,5-trifluoro-DL-leucine (TFL) derived from diploid awamori yeast of Saccharomyces cerevisiae. Some of the mutants accumulated a greater amount of intracellular L-leucine, and among them, one mutant overproduced i-AmOH in awamori brewing. This mutant carried an allele of the LEU4 gene encoding the Ser542Phe/Ala551Val variant IPMS, which is less sensitive to feedback inhibition by L-leucine. Interestingly, we found that either of the constituent mutations (LEU4(S542F) and LEU4(A551V)) resulted in the TFL tolerance of yeast cells and desensitization to L-leucine feedback inhibition of IPMS, leading to intracellular L-leucine accumulation. Homology modeling also suggested that L-leucine binding was drastically inhibited in the Ser542Phe, Ala551Val, and Ser542Phe/Ala551Val variants due to steric hindrance in the cavity of IPMS. As we expected, awamori yeast cells expressing LEU4(S542F), LEU4(A551V), and LEU4(S542F/A551V) showed a prominent increase in extracellular i-AmOH production, compared with that of cells carrying the vector only. The approach described here could be a practical method for the breeding of novel awamori yeasts to expand the diversity of awamori taste and flavor. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  5. Differentiation of enzymatic activity of yeasts and yeast-like microorganisms isolated from various environments

    Directory of Open Access Journals (Sweden)

    Elżbieta Bogusławska-Wąs

    2014-08-01

    Full Text Available The aim of study was to determinate enzymatic activity of yeast-like organisms - Candida lipolytica, Rhodotorula rubra, Trichosporon beigelii, Zygosaccharomyces sp. - isolated from the Szczecin Lagoon and herring salads. We have shown that lipolytic activity was higher than protcolytic for every strain tested. The lowest activity level was found out for amylolytic hydrolases. The results also demonstrated that yeast-like organisms isolated from the Szczecin Lagoon revealed much higher average enzymatic activity compared to tbe same species isolated from herring salads, excepting C. lipolytica.

  6. Determination of the autolysis of champagne yeast by using 14C-labelled yeast

    International Nuclear Information System (INIS)

    Molnar, I.; Oura, E.; Suomalainen, H.

    1980-01-01

    The degree of autolysis of 14 C-labelled Champagne Hautvillers yeast was studied in the function of different temperatures of storage. A linear relationship was found between the length of the storage and the degree of autolysis. The rate of autolysis increased with raising the temperature of storage. The raising of the temperature by 10 deg C was followed by a 6-7% increase in the rate of autolysis. Shaking up the yeast sediment at 20-day intervals raised the rate of autolysis by 1.5-4.2%. (author)

  7. Determination of the autolysis of champagne yeast by using /sup 14/C-labelled yeast

    Energy Technology Data Exchange (ETDEWEB)

    Molnar, I [Orszagos Szoeleszeti es Boraszati Kutatointezet, Budapest (Hungary); Oura, E; Suomalainen, H [Research Laboratories of the State Alcohol Monopoly, Helsinki (Finland)

    1980-01-01

    The degree of autolysis of /sup 14/C-labelled Champagne Hautvillers yeast was studied in the function of different temperatures of storage. A linear relationship was found between the length of the storage and the degree of autolysis. The rate of autolysis increased with raising the temperature of storage. The raising of the temperature by 10 deg C was followed by a 6-7% increase in the rate of autolysis. Shaking up the yeast sediment at 20-day intervals raised the rate of autolysis by 1.5-4.2%.

  8. Yeast Metabolites of Glycated Amino Acids in Beer.

    Science.gov (United States)

    Hellwig, Michael; Beer, Falco; Witte, Sophia; Henle, Thomas

    2018-06-01

    Glycation reactions (Maillard reactions) during the malting and brewing processes are important for the development of the characteristic color and flavor of beer. Recently, free and protein-bound Maillard reaction products (MRPs) such as pyrraline, formyline, and maltosine were found in beer. Furthermore, these amino acid derivatives are metabolized by Saccharomyces cerevisiae via the Ehrlich pathway. In this study, a method was developed for quantitation of individual Ehrlich intermediates derived from pyrraline, formyline, and maltosine. Following synthesis of the corresponding reference material, the MRP-derived new Ehrlich alcohols pyrralinol (up to 207 μg/L), formylinol (up to 50 μg/L), and maltosinol (up to 6.9 μg/L) were quantitated for the first time in commercial beer samples by reverse phase high performance liquid chromatography tandem mass spectrometry in the multiple reaction monitoring mode. This is equivalent to ca. 20-40% of the concentrations of the parent glycated amino acids. The metabolites were almost absent from alcohol-free beers and malt-based beverages. Two previously unknown valine-derived pyrrole derivatives were characterized and qualitatively identified in beer. The metabolites investigated represent new process-induced alkaloids that may influence brewing yeast performance due to structural similarities to quorum sensing and metal-binding molecules.

  9. Survival of synchronized diploid yeast after ultraviolet irradiation

    International Nuclear Information System (INIS)

    Nunes, E.; Lorido, L.; Gelos, U.

    1975-01-01

    Synchronized populations of diploid yeast were exposed to uv light and their survival thereafter upon immediate plating (IP) and after liquid holding (LH) treatment in the presence and absence of caffeine was examined. These cells were found to be most resistant to uv light during early budding (G 2 period). The effect of LH is positive throughout the cell cycle and is dependent on the radiosensitivity of the cells upon IP. Caffeine-sensitive and caffeine-insensitive components of dark repair were demonstrated. The uv light responses of logarithmic growing and synchronized populations were compared with x-ray responses of the same strain analyzed under the same conditions in a previous work. The pattern of variation in sensitivity throughout the cell cycle and the ability to recover are qualitatively similar. The caffeine-insensitive component of repair has a similar efficiency in uv and x-irradiated G 1 cells, increasing in uv-irradiated cells after the beginning of the DNA synthetic period and during the G 2 period. The findings observed under IP conditions are consistent with a model already proposed which requires the repair efficiency to oscillate during the cell cycle. The results suggest that repair pathways for lethal uv damage may share some common steps with those for x-ray damage

  10. Enhanced mitochondrial degradation of yeast cytochrome c with amphipathic structures.

    Science.gov (United States)

    Chen, Xi; Moerschell, Richard P; Pearce, David A; Ramanan, Durga D; Sherman, Fred

    2005-02-01

    The dispensable N-terminus of iso-1-cytochrome c (iso-1) in the yeast Saccharomyces cerevisiae was replaced by 11 different amphipathic structures. Rapid degradation of the corresponding iso-1 occurred, with the degree of degradation increasing with the amphipathic moments; and this amphipathic-dependent degradation was designated ADD. ADD occurred with the holo-forms in the mitochondria but not as the apo-forms in the cytosol. The extreme mutant type degraded with a half-life of approximately 12 min, whereas the normal iso-1 was stable over hours. ADD was influenced by the rho+/rho- state and by numerous chromosomal genes. Most importantly, ADD appeared to be specifically suppressed to various extents by deletions of any of the YME1, AFG3, or RCA1 genes encoding membrane-associated mitochondrial proteases, probably because the amphipathic structures caused a stronger association with the mitochondrial inner membrane and its associated proteases. The use of ADD assisted in the differentiation of substrates of different mitochondrial degradation pathways.

  11. Rapid customised operon assembly by yeast recombinational cloning.

    Science.gov (United States)

    Liu, Michael A; Kenyon, Johanna J; Lee, Jason; Reeves, Peter R

    2017-06-01

    We have developed a system called the Operon Assembly Protocol (OAP), which takes advantage of the homologous recombination DNA repair pathway in Saccharomyces cerevisiae to assemble full-length operons from a series of overlapping PCR products into a specially engineered yeast-Escherichia coli shuttle vector. This flexible, streamlined system can be used to assemble several operon clones simultaneously, and each clone can be expressed in the same E. coli tester strain to facilitate direct functional comparisons. We demonstrated the utility of the OAP by assembling and expressing a series of E. coli O1A O-antigen gene cluster clones containing various gene deletions or replacements. We then used these constructs to assess the substrate preferences of several Wzx flippases, which are responsible for translocation of oligosaccharide repeat units (O units) across the inner membrane during O-antigen biosynthesis. We were able to identify several O unit structural features that appear to be important determinants of Wzx substrate preference. The OAP system should be broadly applicable for the genetic manipulation of any bacterial operon and can be modified for use in other host species. It could also have potential uses in fields such as glycoengineering.

  12. Recreating the synthesis of starch granules in yeast

    Science.gov (United States)

    Pfister, Barbara; Sánchez-Ferrer, Antoni; Diaz, Ana; Lu, Kuanjen; Otto, Caroline; Holler, Mirko; Shaik, Farooque Razvi; Meier, Florence; Mezzenga, Raffaele; Zeeman, Samuel C

    2016-01-01

    Starch, as the major nutritional component of our staple crops and a feedstock for industry, is a vital plant product. It is composed of glucose polymers that form massive semi-crystalline granules. Its precise structure and composition determine its functionality and thus applications; however, there is no versatile model system allowing the relationships between the biosynthetic apparatus, glucan structure and properties to be explored. Here, we expressed the core Arabidopsis starch-biosynthesis pathway in Saccharomyces cerevisiae purged of its endogenous glycogen-metabolic enzymes. Systematic variation of the set of biosynthetic enzymes illustrated how each affects glucan structure and solubility. Expression of the complete set resulted in dense, insoluble granules with a starch-like semi-crystalline organization, demonstrating that this system indeed simulates starch biosynthesis. Thus, the yeast system has the potential to accelerate starch research and help create a holistic understanding of starch granule biosynthesis, providing a basis for the targeted biotechnological improvement of crops. DOI: http://dx.doi.org/10.7554/eLife.15552.001 PMID:27871361

  13. Post-transcriptional regulation of ribosome biogenesis in yeast

    Directory of Open Access Journals (Sweden)

    Isabelle C. Kos-Braun

    2017-05-01

    Full Text Available Most microorganisms are exposed to the constantly and often rapidly changing environment. As such they evolved mechanisms to balance their metabolism and energy expenditure with the resources available to them. When resources become scarce or conditions turn out to be unfavourable for growth, cells reduce their metabolism and energy usage to survive. One of the major energy consuming processes in the cell is ribosome biogenesis. Unsurprisingly, cells encountering adverse conditions immediately shut down production of new ribosomes. It is well established that nutrient depletion leads to a rapid repression of transcription of the genes encoding ribosomal proteins, ribosome biogenesis factors as well as ribosomal RNA (rRNA. However, if pre-rRNA processing and ribosome assembly are regulated post-transcriptionally remains largely unclear. We have recently uncovered that the yeast Saccharomyces cerevisiae rapidly switches between two alternative pre-rRNA processing pathways depending on the environmental conditions. Our findings reveal a new level of complexity in the regulation of ribosome biogenesis.

  14. Effect of heat treatment on brewer's yeast fermentation activity

    OpenAIRE

    Kharandiuk, Tetiana; Kosiv, Ruslana; Palianytsia, Liubov; Berezovska, Natalia

    2015-01-01

    The influence of temperature treatment of brewer's yeast strain Saflager W-34/70 at temperatures of -17, 20, 25, 30, 35, 40 °C on their fermentative activity was studied. It was established that the freezing of yeast leads to a decrease of fermentation activity in directly proportional to the duration way. Fermentative activity of yeast samples can be increased by 20-24% by heat treatment at 35 °C during 15-30 minutes.

  15. Using Microsatellites to Identify Yeast Strains in Beer

    OpenAIRE

    Bruke, Alexandria; Van Brocklin, Jennifer; Rivest, Jason; Prenni, Jessica E.; Ibrahim, Hend

    2012-01-01

    Yeast is an integral part of the brewing process and is responsible for much of the taste and characteristics of beer. During the brewing process, yeast is subject to ageing and stress factors that can result in growth inhibition, decreased genetic stability, and changes in cell membrane stability. Characterization of yeast species used in industrial fermentation (e.g. S. cerevisiae) is of great importance to the brewing industry. The objective of this study was to develop an assay to identif...

  16. Yeast replicative aging: a paradigm for defining conserved longevity interventions

    OpenAIRE

    Wasko, Brian M.; Kaeberlein, Matt

    2013-01-01

    The finite replicative life span of budding yeast mother cells was demonstrated as early as 1959, but the idea that budding yeast could be used to model aging of multicellular eukaryotes did not enter the scientific mainstream until relatively recently. Despite continued skepticism by some, there are now abundant data that several interventions capable of extending yeast replicative life span have a similar effect in multicellular eukaryotes including nematode worms, fruit flies, and rodents....

  17. Yeast species associated with the spontaneous fermentation of cider.

    OpenAIRE

    Suárez, Belén; Pando, Rosa; Fernández, Norman; Querol, Amparo; Rodríguez, Roberto

    2018-01-01

    This paper reports the influence of cider-making technology (pneumatic and traditional pressing) on the dynamics of wild yeast populations. Yeast colonies isolated from apple juice before and throughout fermentation at a cider cellar of Asturias (Spain), during two consecutive years were studied. The yeast strains were identified by restriction fragment length polymorphism analysis of the 5.8S rRNA gene and the two flanking internal transcribed sequences (ITS). The musts obtained by ...

  18. Probiotic properties of yeasts occurring in fermented food and beverages

    DEFF Research Database (Denmark)

    Jespersen, Lene

    Besides being able to improve the quality and safety of many fermented food and beverages some yeasts offer a number of probiotic traits. Especially a group of yeast referred to as "Saccharomyces boulardii", though taxonomically belonging to Saccharomyces cerevisiae, has been claimed to have...... probiotic properties. Besides, yeasts naturally occurring globally in food and beverages will have traits that might have a positive impact on human health....

  19. Study on ionizing radiosensitivity of respiratory deficiency yeast mutants

    International Nuclear Information System (INIS)

    Mao Shuhong; Chinese Academy of Sciences, Beijing; Jin Genming; Wei Zengquan; Xie Hongmei

    2006-01-01

    The radiosensitivity of respiratory deficiency yeast mutants has been studied in this work. The mutants which were screened from the yeasts after ionizing irradiation were irradiated with 12 C 6+ at different doses. Because of the great change in its mitochondria and mitochondrial DNA, the respiratory deficiency yeast mutants show radio-sensitivity at dose less than 1 Gy and radioresistance at doses higher than 1 Gy. (authors)

  20. Endolysosomal pathway activity protects cells from neurotoxic TDP-43

    Directory of Open Access Journals (Sweden)

    Christine Leibiger

    2018-03-01

    Full Text Available The accumulation of protein aggregates in neurons is a typical pathological hallmark of the motor neuron disease amyotrophic lateral sclerosis (ALS and of frontotemporal dementia (FTD. In many cases, these aggregates are composed of the 43 kDa TAR DNA-binding protein (TDP‑43. Using a yeast model for TDP‑43 proteinopathies, we observed that the vacuole (the yeast equivalent of lysosomes markedly contributed to the degradation of TDP‑43. This clearance occurred via TDP‑43-containing vesicles fusing with the vacuole through the concerted action of the endosomal-vacuolar (or endolysosomal pathway and autophagy. In line with its dominant role in the clearance of TDP‑43, endosomal-vacuolar pathway activity protected cells from the detrimental effects of TDP‑43. In contrast, enhanced autophagy contributed to TDP‑43 cytotoxicity, despite being involved in TDP‑43 degradation. TDP‑43’s interference with endosomal-vacuolar pathway activity may have two deleterious consequences. First, it interferes with its own degradation via this pathway, resulting in TDP‑43 accumulation. Second, it affects vacuolar proteolytic activity, which requires endosomal-vacuolar trafficking. We speculate that the latter contributes to aberrant autophagy. In sum, we propose that ameliorating endolysosomal pathway activity enhances cell survival in TDP‑43-associated diseases.

  1. Yeast Interacting Proteins Database: YNL189W, YLR328W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available ait as prey (0) YLR328W NMA1 Nicotinic acid mononucleotide adenylyltransferase, involved in pathways... of NAD biosynthesis, including the de novo, NAD(+) salvage, and nicotinamide riboside salvage pathways... Nicotinic acid mononucleotide adenylyltransferase, involved in pathways of NAD biosynthesis, including the ...de novo, NAD(+) salvage, and nicotinamide riboside salvage pathways Rows with this prey as prey Rows with th

  2. Yeast Interacting Proteins Database: YGR010W, YLR328W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available 1 Nicotinic acid mononucleotide adenylyltransferase, involved in pathways of NAD biosynthesis, including the... de novo, NAD(+) salvage, and nicotinamide riboside salvage pathways Rows with th...ne name NMA1 Prey description Nicotinic acid mononucleotide adenylyltransferase, involved in pathways of NAD... biosynthesis, including the de novo, NAD(+) salvage, and nicotinamide riboside salvage pathways

  3. Yeast Interacting Proteins Database: YML064C, YLR328W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available th this bait as prey (0) YLR328W NMA1 Nicotinic acid mononucleotide adenylyltransferase, involved in pathways... of NAD biosynthesis, including the de novo, NAD(+) salvage, and nicotinamide riboside salvage pathways...ic acid mononucleotide adenylyltransferase, involved in pathways of NAD biosynthe...sis, including the de novo, NAD(+) salvage, and nicotinamide riboside salvage pathways Rows with this prey a

  4. Liquid holding recovery kinetics in yeast cells with regard to radiation quality

    International Nuclear Information System (INIS)

    Kim, Jin Kyu; Lee, Byoung Hun; Petin, Vladislav G.

    2004-01-01

    It is widely accepted that the RBE of ionizing radiation with a high linear energy transfer (LET) is dependent both on the increased probability of primary damage production (physical events) and the reduced ability of a cell for post-irradiation recovery (biological events). A relatively unexpected role of the specific repair pathways in the RBE of high-LET radiation was demonstrated for bacterial, yeast and mammalian cells. It seems to exist a common agreement that high-LET radiations produce more portion of damage that are considered to be irreversible compared with low-LET radiation such as photons. Cellular recovery and repair of radiation-induced DNA double-strand breaks (DSB) could be also dependent upon radiation quality. Studies concerning the rate of the recovery and repair from radiation damage produced with low- and high-LET radiations in cells of various origins on the survival and macromolecular level have also revealed that in general at a high ionization density, these processes may be reduced or even absent. When irradiated yeast cells are held in a liquid non-nutrient media at 30 .deg. C before planting on to a growth medium, their survival increases. This phenomena is known as liquid holding recovery (LHR). A quantitative approach describing the LHR kinetics of the yeast cells was described, which enables the estimation of the probability of the recovery per unit time and the fraction of the irreversible damage. The main goals of this study were (i) to answer the question whether or not high-LET radiation affects the recovery process itself or if it only produces a higher level of severe irreversible damage that cannot be repaired at all; (ii) to elucidate the role of irreversible damage and the probability of recovery in some rad mutants of the yeast Saccharomyces cerevisiae. In this study, the liquid-holing recovery will serve as an indicator of the cellular repair activity

  5. Aboveground Deadwood Deposition Supports Development of Soil Yeasts

    Directory of Open Access Journals (Sweden)

    Thorsten Wehde

    2012-12-01

    Full Text Available Unicellular saprobic fungi (yeasts inhabit soils worldwide. Although yeast species typically occupy defined areas on the biome scale, their distribution patterns within a single type of vegetation, such as forests, are more complex. In order to understand factors that shape soil yeast communities, soils collected underneath decaying wood logs and under forest litter were analyzed. We isolated and identified molecularly a total of 25 yeast species, including three new species. Occurrence and distribution of yeasts isolated from these soils provide new insights into ecology and niche specialization of several soil-borne species. Although abundance of typical soil yeast species varied among experimental plots, the analysis of species abundance and community composition revealed a strong influence of wood log deposition and leakage of organic carbon. Unlike soils underneath logs, yeast communities in adjacent areas harbored a considerable number of transient (phylloplane-related yeasts reaching 30% of the total yeast quantity. We showed that distinguishing autochthonous community members and species transient in soils is essential to estimate appropriate effects of environmental factors on soil fungi. Furthermore, a better understanding of species niches is crucial for analyses of culture-independent data, and may hint to the discovery of unifying patterns of microbial species distribution.

  6. The ecology of the Drosophila-yeast mutualism in wineries

    Science.gov (United States)

    2018-01-01

    The fruit fly, Drosophila melanogaster, is preferentially found on fermenting fruits. The yeasts that dominate the microbial communities of these substrates are the primary food source for developing D. melanogaster larvae, and adult flies manifest a strong olfactory system-mediated attraction for the volatile compounds produced by these yeasts during fermentation. Although most work on this interaction has focused on the standard laboratory yeast Saccharomyces cerevisiae, a wide variety of other yeasts naturally ferment fallen fruit. Here we address the open question of whether D. melanogaster preferentially associates with distinct yeasts in different, closely-related environments. We characterized the spatial and temporal dynamics of Drosophila-associated fungi in Northern California wineries that use organic grapes and natural fermentation using high-throughput, short-amplicon sequencing. We found that there is nonrandom structure in the fungal communities that are vectored by flies both between and within vineyards. Within wineries, the fungal communities associated with flies in cellars, fermentation tanks, and pomace piles are distinguished by varying abundances of a small number of yeast species. To investigate the origins of this structure, we assayed Drosophila attraction to, oviposition on, larval development in, and longevity when consuming the yeasts that distinguish vineyard microhabitats from each other. We found that wild fly lines did not respond differentially to the yeast species that distinguish winery habitats in habitat specific manner. Instead, this subset of yeast shares traits that make them attractive to and ensure their close association with Drosophila. PMID:29768432

  7. Effect of fungicides on epiphytic yeasts associated with strawberry

    Science.gov (United States)

    Debode, Jane; Van Hemelrijck, Wendy; Creemers, Piet; Maes, Martine

    2013-01-01

    We studied the effect of two commonly used fungicides on the epiphytic yeast community of strawberry. Greenhouse and field experiments were conducted applying Switch (cyprodinil plus fludioxonil) or Signum (boscalid plus pyraclostrobin) to strawberry plants. Yeasts on leaves and fruits were assessed on treated and untreated plants at several time points via plating and denaturing gradient gel electrophoresis (DGGE) analysis. The yeast counts on plates of the treated plants were similar to the control plants. Unripe fruits had 10 times larger yeast concentrations than ripe fruits or leaves. Some dominant yeast types were isolated and in vitro tests showed that they were at least 10 times less sensitive to Switch and Signum as compared with two important fungal strawberry pathogens Botrytis cinerea and Colletotrichum acutatum, which are the targets for the fungicide control. DGGE analysis showed that the applied fungicides had no effect on the composition of the yeast communities, while the growing system, strawberry tissue, and sampling time did affect the yeast communities. The yeast species most commonly identified were Cryptococcus, Rhodotorula, and Sporobolomyces. These results point toward the potential applicability of natural occurring yeast antagonists into an integrated disease control strategy for strawberry diseases.

  8. Yeast Interacting Proteins Database: YLR328W, YLR328W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available YLR328W NMA1 Nicotinic acid mononucleotide adenylyltransferase, involved in pathways... of NAD biosynthesis, including the de novo, NAD(+) salvage, and nicotinamide riboside salvage pathways Row...ylyltransferase, involved in pathways of NAD biosynthesis, including the de novo,... NAD(+) salvage, and nicotinamide riboside salvage pathways Rows with this prey as prey (4) Rows with this p... description Nicotinic acid mononucleotide adenylyltransferase, involved in pathways

  9. Cell organisation, sulphur metabolism and ion transport-related genes are differentially expressed in Paracoccidioides brasiliensis mycelium and yeast cells

    Directory of Open Access Journals (Sweden)

    Passos Geraldo AS

    2006-08-01

    Full Text Available Abstract Background Mycelium-to-yeast transition in the human host is essential for pathogenicity by the fungus Paracoccidioides brasiliensis and both cell types are therefore critical to the establishment of paracoccidioidomycosis (PCM, a systemic mycosis endemic to Latin America. The infected population is of about 10 million individuals, 2% of whom will eventually develop the disease. Previously, transcriptome analysis of mycelium and yeast cells resulted in the assembly of 6,022 sequence groups. Gene expression analysis, using both in silico EST subtraction and cDNA microarray, revealed genes that were differential to yeast or mycelium, and we discussed those involved in sugar metabolism. To advance our understanding of molecular mechanisms of dimorphic transition, we performed an extended analysis of gene expression profiles using the methods mentioned above. Results In this work, continuous data mining revealed 66 new differentially expressed sequences that were MIPS(Munich Information Center for Protein Sequences-categorised according to the cellular process in which they are presumably involved. Two well represented classes were chosen for further analysis: (i control of cell organisation – cell wall, membrane and cytoskeleton, whose representatives were hex (encoding for a hexagonal peroxisome protein, bgl (encoding for a 1,3-β-glucosidase in mycelium cells; and ags (an α-1,3-glucan synthase, cda (a chitin deacetylase and vrp (a verprolin in yeast cells; (ii ion metabolism and transport – two genes putatively implicated in ion transport were confirmed to be highly expressed in mycelium cells – isc and ktp, respectively an iron-sulphur cluster-like protein and a cation transporter; and a putative P-type cation pump (pct in yeast. Also, several enzymes from the cysteine de novo biosynthesis pathway were shown to be up regulated in the yeast form, including ATP sulphurylase, APS kinase and also PAPS reductase. Conclusion Taken

  10. twzPEA: A Topology and Working Zone Based Pathway Enrichment Analysis Framework

    Science.gov (United States)

    Sensitive detection of involvement and adaptation of key signaling, regulatory, and metabolic pathways holds the key to deciphering molecular mechanisms such as those in the biomass-to-biofuel conversion process in yeast. Typical gene set enrichment analyses often do not use topology information in...

  11. Scalable interrogation: Eliciting human pheromone responses to deception in a security interview setting.

    Science.gov (United States)

    Stedmon, Alex W; Eachus, Peter; Baillie, Les; Tallis, Huw; Donkor, Richard; Edlin-White, Robert; Bracewell, Robert

    2015-03-01

    Individuals trying to conceal knowledge from interrogators are likely to experience raised levels of stress that can manifest itself across biological, physiological, psychological and behavioural factors, providing an opportunity for detection. Using established research paradigms an innovative scalable interrogation was designed in which participants were given a 'token' that represented information they had to conceal from interviewers. A control group did not receive a token and therefore did not have to deceive the investigators. The aim of this investigation was to examine differences between deceivers and truth-tellers across the four factors by collecting data for cortisol levels, sweat samples, heart-rate, respiration, skin temperature, subjective stress ratings and video and audio recordings. The results provided an integrated understanding of responses to interrogation by those actively concealing information and those acting innocently. Of particular importance, the results also suggest, for the first time in an interrogation setting, that stressed individuals may secrete a volatile steroid based marker that could be used for stand-off detection. The findings are discussed in relation to developing a scalable interrogation protocol for future research in this area. Copyright © 2014 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  12. Dose-dependent pheromone responses of mountain pine beetle in stands of lodgepole pine

    Science.gov (United States)

    Daniel R. Miller; B. Staffan Lindgren; John H. Borden

    2005-01-01

    We conducted seven behavioral choice tests with Lindgren multiple-funnel traps in stands of mature lodgepole pine in British Columbia, from 1988 to 1994, to determine the dosedependent responses of the mountain pine beetle, Dendroctonus ponderosae Hopkins, to its pheromones. Amultifunctional dose-dependent response was exhibited by D. ...

  13. Multimodal stimulation of Colorado potato beetle reveals modulation of pheromone response by yellow light.

    Directory of Open Access Journals (Sweden)

    Fernando Otálora-Luna

    Full Text Available Orientation of insects to host plants and conspecifics is the result of detection and integration of chemical and physical cues present in the environment. Sensory organs have evolved to be sensitive to important signals, providing neural input for higher order multimodal processing and behavioral output. Here we report experiments to determine decisions made by Colorado potato beetle (CPB, Leptinotarsa decemlineata, in response to isolated stimuli and multimodal combinations of signals on a locomotion compensator. Our results show that in complete darkness and in the absence of other stimuli, pheromonal stimulation increases attraction behavior of CPB as measured in oriented displacement and walking speed. However, orientation to the pheromone is abolished when presented with the alternative stimulation of a low intensity yellow light in a dark environment. The ability of the pheromone to stimulate these diurnal beetles in the dark in the absence of other stimuli is an unexpected but interesting observation. The predominance of the phototactic response over that to pheromone when low intensity lights were offered as choices seems to confirm the diurnal nature of the insect. The biological significance of the response to pheromone in the dark is unclear. The phototactic response will play a key role in elucidating multimodal stimulation in the host-finding process of CPB, and perhaps other insects. Such information might be exploited in the design of applications to attract and trap CPB for survey or control purposes and other insect pests using similar orientation mechanisms.

  14. Yeast tRNAPhe expressed in human cells can be selected by HIV-1 for use as a reverse transcription primer

    International Nuclear Information System (INIS)

    Kelly, Nathan J.; Morrow, Casey D.

    2003-01-01

    All naturally occurring human immune deficiency viruses (HIV-1) select and use tRNA Lys,3 as the primer for reverse transcription. Studies to elucidate the mechanism of tRNA selection from the intracellular milieu have been hampered due to the difficulties in manipulating the endogenous levels of tRNA Lys,3 . We have previously described a mutant HIV-1 with a primer binding site (PBS) complementary to yeast tRNA Phe (psHIV-Phe) that relies on transfection of yeast tRNA Phe for infectivity. To more accurately recapitulate the selection process, a cDNA was designed for the intracellular expression of the yeast tRNA Phe . Increasing amounts of the plasmid encoding tRNA Phe resulted in a corresponding increase in levels of yeast tRNA Phe in the cell. The yeast tRNA Phe isolated from cells transfected with the cDNA for yeast tRNA Phe , or in the cell lines expressing yeast tRNA Phe , were aminoacylated, indicating that the expressed yeast tRNA Phe was incorporated into tRNA biogenesis pathways and translation. Increasing the cytoplasmic levels of tRNA Phe resulted in increased encapsidation of tRNA Phe in viruses with a PBS complementary to tRNA Phe (psHIV-Phe) or tRNA Lys,3 (wild-type HIV-1). Production of infectious psHIV-Phe was dependent on the amount of cotransfected tRNA Phe cDNA. Increasing amounts of plasmids encoding yeast tRNA Phe produced an increase of infectious psHIV-Phe that plateaued at a level lower than that from the transfection of the wild-type genome, which uses tRNA Lys,3 as the primer for reverse transcription. Cell lines were generated that expressed yeast tRNA Phe at levels approximately 0.1% of that for tRNA Lys,3 . Even with this reduced level of yeast tRNA Phe , the cell lines complemented psHIV-Phe over background levels. The results of these studies demonstrate that intracellular levels of primer tRNA can have a direct effect on HIV-1 infectivity and further support the role for PBS-tRNA complementarity in the primer selection process

  15. Industrial systems biology and its impact on synthetic biology of yeast cell factories.

    Science.gov (United States)

    Fletcher, Eugene; Krivoruchko, Anastasia; Nielsen, Jens

    2016-06-01

    Engineering industrial cell factories to effectively yield a desired product while dealing with industrially relevant stresses is usually the most challenging step in the development of industrial production of chemicals using microbial fermentation processes. Using synthetic biology tools, microbial cell factories such as Saccharomyces cerevisiae can be engineered to express synthetic pathways for the production of fuels, biopharmaceuticals, fragrances, and food flavors. However, directing fluxes through these synthetic pathways towards the desired product can be demanding due to complex regulation or poor gene expression. Systems biology, which applies computational tools and mathematical modeling to understand complex biological networks, can be used to guide synthetic biology design. Here, we present our perspective on how systems biology can impact synthetic biology towards the goal of developing improved yeast cell factories. Biotechnol. Bioeng. 2016;113: 1164-1170. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  16. Development of a yeast cell factory for production of aromatic products

    DEFF Research Database (Denmark)

    Rodriguez Prado, Edith Angelica; Kildegaard, Kanchana Rueksomtawin; Li, Mingji

    2014-01-01

    There is much interest in aromatic chemicals in the chemical industry as these can be used for production of dyes, anti-oxidants, nutraceuticals and food ingredients. Yeast is a widely used cell factory and it is particularly well suited for production of aromatic chemicals via complex biosynthetic...... routes involving P450 enzymes. In Saccharomyces cerevisiae the fluxes towards aromatic acids (L-tryptophan, L-tyrosine and L-phenylalanine) are strictly controlled on transcriptional and kinetic levels and therefore are difficult to manipulate. We engineered S. cerevisiae for increased production...... of aromatic compounds by eliminating degradation, up-regulating the key enzyme encoding genes, and removing feed-back inhibition in the pathway. In order to test the strain performance we overexpressed heterologous pathway for coumaric acid production. We obtained 4-fold higher concentrations of coumaric acid...

  17. S-Adenosyl-L-methionine protects the probiotic yeast, Saccharomyces boulardii, from acid-induced cell death.

    Science.gov (United States)

    Cascio, Vincent; Gittings, Daniel; Merloni, Kristen; Hurton, Matthew; Laprade, David; Austriaco, Nicanor

    2013-02-13

    Saccharomyces boulardii is a probiotic yeast routinely used to prevent and to treat gastrointestinal disorders, including the antibiotic-associated diarrhea caused by Clostridium difficile infections. However, only 1-3% of the yeast administered orally is recovered alive in the feces suggesting that this yeast is unable to survive the acidic environment of the gastrointestinal tract. We provide evidence that suggests that S. boulardii undergoes programmed cell death (PCD) in acidic environments, which is accompanied by the generation of reactive oxygen species and the appearance of caspase-like activity. To better understand the mechanism of cell death at the molecular level, we generated microarray gene expression profiles of S. boulardii cells cultured in an acidic environment. Significantly, functional annotation revealed that the up-regulated genes were significantly over-represented in cell death pathways Finally, we show that S-adenosyl-L-methionine (AdoMet), a commercially available, FDA-approved dietary supplement, enhances the viability of S. boulardii in acidic environments, most likely by preventing programmed cell death. In toto, given the observation that many of the proven health benefits of S. boulardii are dependent on cell viability, our data suggests that taking S. boulardii and AdoMet together may be a more effective treatment for gastrointestinal disorders than taking the probiotic yeast alone.

  18. Genome-wide screening for genes whose deletions confer sensitivity to mutagenic purine base analogs in yeast

    Directory of Open Access Journals (Sweden)

    Kozmin Stanislav G

    2005-06-01

    Full Text Available Abstract Background N-hydroxylated base analogs, such as 6-hydroxylaminopurine (HAP and 2-amino-6-hydroxylaminopurine (AHA, are strong mutagens in various organisms due to their ambiguous base-pairing properties. The systems protecting cells from HAP and related noncanonical purines in Escherichia coli include specialized deoxyribonucleoside triphosphatase RdgB, DNA repair endonuclease V, and a molybdenum cofactor-dependent system. Fewer HAP-detoxification systems have been identified in yeast Saccharomyces cerevisiae and other eukaryotes. Cellular systems protecting from AHA are unknown. In the present study, we performed a genome-wide search for genes whose deletions confer sensitivity to HAP and AHA in yeast. Results We screened the library of yeast deletion mutants for sensitivity to the toxic and mutagenic action of HAP and AHA. We identified novel genes involved in the genetic control of base analogs sensitivity, including genes controlling purine metabolism, cytoskeleton organization, and amino acid metabolism. Conclusion We developed a method for screening the yeast deletion library for sensitivity to the mutagenic and toxic action of base analogs and identified 16 novel genes controlling pathways of protection from HAP. Three of them also protect from AHA.

  19. Genetically modified yeast species and fermentation processes using genetically modified yeast

    Science.gov (United States)

    Rajgarhia, Vineet [Kingsport, TN; Koivuranta, Kari [Helsinki, FI; Penttila, Merja [Helsinki, FI; Ilmen, Marja [Helsinki, FI; Suominen, Pirkko [Maple Grove, MN; Aristidou, Aristos [Maple Grove, MN; Miller, Christopher Kenneth [Cottage Grove, MN; Olson, Stacey [St. Bonifacius, MN; Ruohonen, Laura [Helsinki, FI

    2011-05-17

    Yeast cells are transformed with an exogenous xylose isomerase gene. Additional genetic modifications enhance the ability of the transformed cells to ferment xylose to ethanol or other desired fermentation products. Those modifications', include deletion of non-specific or specific aldose reductase gene(s), deletion of xylitol dehydrogenase gene(s) and/or overexpression of xylulokinase.

  20. Yeast Interacting Proteins Database: YFR015C, YLR258W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available yeast homolog; expression induced by glucose limitation, nitrogen starvation, environmental stress, and entr...n synthase, similar to Gsy1p; expression induced by glucose limitation, nitrogen ...; expression induced by glucose limitation, nitrogen starvation, environmental stress, and entry into statio...ogen synthase, similar to Gsy1p; expression induced by glucose limitation, nitrogen starvation, heat shock,

  1. Yeast cell differentiation: Lessons from pathogenic and non-pathogenic yeasts

    Czech Academy of Sciences Publication Activity Database

    Pálková, Z.; Váchová, Libuše

    2016-01-01

    Roč. 57, SEP (2016), s. 110-119 ISSN 1084-9521 R&D Projects: GA ČR GA13-08605S; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61388971 Keywords : Pathogenic yeasts * Biofilms and colonies * Cell differentiation Subject RIV: EE - Microbiology, Virology Impact factor: 6.614, year: 2016

  2. Genetically modified yeast species, and fermentation processes using genetically modified yeast

    Energy Technology Data Exchange (ETDEWEB)

    Rajgarhia, Vineet [Kingsport, TN; Koivuranta, Kari [Helsinki, FI; Penttila, Merja [Helsinki, FI; Ilmen, Marja [Helsinki, FI; Suominen, Pirkko [Maple Grove, MN; Aristidou, Aristos [Maple Grove, MN; Miller, Christopher Kenneth [Cottage Grove, MN; Olson, Stacey [St. Bonifacius, MN; Ruohonen, Laura [Helsinki, FI

    2014-01-07

    Yeast cells are transformed with an exogenous xylose isomerase gene. Additional genetic modifications enhance the ability of the transformed cells to ferment xylose to ethanol or other desired fermentation products. Those modifications include deletion of non-specific aldose reductase gene(s), deletion of xylitol dehydrogenase gene(s) and/or overexpression of xylulokinase.

  3. Genetically modified yeast species, and fermentation processes using genetically modified yeast

    Energy Technology Data Exchange (ETDEWEB)

    Rajgarhia, Vineet; Koivuranta, Kari; Penttila, Merja; Ilmen, Marja; Suominen, Pirkko; Aristidou, Aristos; Miller, Christopher Kenneth; Olson, Stacey; Ruohonen, Laura

    2017-09-12

    Yeast cells are transformed with an exogenous xylose isomerase gene. Additional genetic modifications enhance the ability of the transformed cells to ferment xylose to ethanol or other desired fermentation products. Those modifications include deletion of non-specific or specific aldose reductase gene(s), deletion of xylitol dehydrogenase gene(s) and/or overexpression of xylulokinase.

  4. Genetically modified yeast species, and fermentation processes using genetically modified yeast

    Energy Technology Data Exchange (ETDEWEB)

    Rajgarhia, Vineet; Koivuranta, Kari; Penttila, Merja; Ilmen, Marja; Suominen, Pirkko; Aristidou, Aristos; Miller, Christopher Kenneth; Olson, Stacey; Ruohonen, Laura

    2016-08-09

    Yeast cells are transformed with an exogenous xylose isomerase gene. Additional genetic modifications enhance the ability of the transformed cells to ferment xylose to ethanol or other desired fermentation products. Those modifications include deletion of non-specific or specific aldose reductase gene(s), deletion of xylitol dehydrogenase gene(s) and/or overexpression of xylulokinase.

  5. Genetically modified yeast species and fermentation processes using genetically modified yeast

    Energy Technology Data Exchange (ETDEWEB)

    Rajgarhia, Vineet [Kingsport, TN; Koivuranta, Kari [Helsinki, FI; Penttila, Merja [Helsinki, FI; Ilmen, Marja [Helsinki, FI; Suominen, Pirkko [Maple Grove, MN; Aristidou, Aristos [Maple Grove, MN; Miller, Christopher Kenneth [Cottage Grove, MN; Olson, Stacey [St. Bonifacius, MN; Ruohonen, Laura [Helsinki, FI

    2011-05-17

    Yeast cells are transformed with an exogenous xylose isomerase gene. Additional genetic modifications enhance the ability of the transformed cells to ferment xylose to ethanol or other desired fermentation products. Those modifications', include deletion of non-specific or specific aldose reductase gene(s), deletion of xylitol dehydrogenase gene(s) and/or overexpression of xylulokinase.

  6. Genetically modified yeast species, and fermentation processes using genetically modified yeast

    Science.gov (United States)

    Rajgarhia, Vineet; Koivuranta, Kari; Penttila, Merja; Ilmen, Marja; Suominen, Pirkko; Aristidou, Aristos; Miller, Christopher Kenneth; Olson, Stacey; Ruohonen, Laura

    2013-05-14

    Yeast cells are transformed with an exogenous xylose isomerase gene. Additional genetic modifications enhance the ability of the transformed cells to ferment xylose to ethanol or other desired fermentation products. Those modifications include deletion of non-specific or specific aldose reductase gene(s), deletion of xylitol dehydrogenase gene(s) and/or overexpression of xylulokinase.

  7. Yeast production from cellulase hydrolyzed furfural industrial waste. II. Conditions for the cultivation of yeast

    Energy Technology Data Exchange (ETDEWEB)

    1977-01-01

    Three yeast strains, Candida AS 2-121, C. utilis AS 2-1180, and C. tropicalis AS 2-637 were selected as being capable of growing on cellulase-hydrolyzed furfural industrial waste. Cell mass yields with respect to C source were approximately 50%. Fermentation conditions are given.

  8. Utilization of spent brewer’s yeast Saccharomyces cerevisiae for the production of yeast enzymatic hydrolysate

    Directory of Open Access Journals (Sweden)

    M Bayarjargal

    2014-09-01

    Full Text Available Spent brewer’s yeast (Saccharomyces cerevisiae is a rich source of protein, vitamins and widely used as a raw material for production of food supplements. The autolysis and enzymatic treatment of spent brewer’s yeast using Pancreatin (2.5% and Flavourzyme (2.5% were performed at 45 °C and 50 °C, respectively. The autolysis and hydrolysis processes were evaluated by determining a soluble solids, soluble protein concentration and α-amino nitrogen content in a reaction mixture. The yield of pancreatic digest and α-amino nitrogen content was high in comparison with autolysis and Flavourzyme treatment. The total solids recovery in dry Yeast hydrolysate was about 50%, a protein and α-amino nitrogen content was 55.9 and 4.8%, respectively. These results show the possibility of utilizing the spent brewer’s yeast as hydrolysate using hydrolytic enzymes and use it as a food supplement after biological experiments.DOI: http://dx.doi.org/10.5564/mjc.v12i0.179 Mongolian Journal of Chemistry Vol.12 2011: 88-91

  9. Studying Functions of All Yeast Genes Simultaneously

    Science.gov (United States)

    Stolc, Viktor; Eason, Robert G.; Poumand, Nader; Herman, Zelek S.; Davis, Ronald W.; Anthony Kevin; Jejelowo, Olufisayo

    2006-01-01

    A method of studying the functions of all the genes of a given species of microorganism simultaneously has been developed in experiments on Saccharomyces cerevisiae (commonly known as baker's or brewer's yeast). It is already known that many yeast genes perform functions similar to those of corresponding human genes; therefore, by facilitating understanding of yeast genes, the method may ultimately also contribute to the knowledge needed to treat some diseases in humans. Because of the complexity of the method and the highly specialized nature of the underlying knowledge, it is possible to give only a brief and sketchy summary here. The method involves the use of unique synthetic deoxyribonucleic acid (DNA) sequences that are denoted as DNA bar codes because of their utility as molecular labels. The method also involves the disruption of gene functions through deletion of genes. Saccharomyces cerevisiae is a particularly powerful experimental system in that multiple deletion strains easily can be pooled for parallel growth assays. Individual deletion strains recently have been created for 5,918 open reading frames, representing nearly all of the estimated 6,000 genetic loci of Saccharomyces cerevisiae. Tagging of each deletion strain with one or two unique 20-nucleotide sequences enables identification of genes affected by specific growth conditions, without prior knowledge of gene functions. Hybridization of bar-code DNA to oligonucleotide arrays can be used to measure the growth rate of each strain over several cell-division generations. The growth rate thus measured serves as an index of the fitness of the strain.

  10. Specificity of transmembrane protein palmitoylation in yeast.

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    Ayelén González Montoro

    Full Text Available Many proteins are modified after their synthesis, by the addition of a lipid molecule to one or more cysteine residues, through a thioester bond. This modification is called S-acylation, and more commonly palmitoylation. This reaction is carried out by a family of enzymes, called palmitoyltransferases (PATs, characterized by the presence of a conserved 50- aminoacids domain called "Asp-His-His-Cys- Cysteine Rich Domain" (DHHC-CRD. There are 7 members of this family in the yeast Saccharomyces cerevisiae, and each of these proteins is thought to be responsible for the palmitoylation of a subset of substrates. Substrate specificity of PATs, however, is not yet fully understood. Several yeast PATs seem to have overlapping specificity, and it has been proposed that the machinery responsible for palmitoylating peripheral membrane proteins in mammalian cells, lacks specificity altogether.Here we investigate the specificity of transmembrane protein palmitoylation in S. cerevisiae, which is carried out predominantly by two PATs, Swf1 and Pfa4. We show that palmitoylation of transmembrane substrates requires dedicated PATs, since other yeast PATs are mostly unable to perform Swf1 or Pfa4 functions, even when overexpressed. Furthermore, we find that Swf1 is highly specific for its substrates, as it is unable to substitute for other PATs. To identify where Swf1 specificity lies, we carried out a bioinformatics survey to identify amino acids responsible for the determination of specificity or Specificity Determination Positions (SDPs and showed experimentally, that mutation of the two best SDP candidates, A145 and K148, results in complete and partial loss of function, respectively. These residues are located within the conserved catalytic DHHC domain suggesting that it could also be involved in the determination of specificity. Finally, we show that modifying the position of the cysteines in Tlg1, a Swf1 substrate, results in lack of palmitoylation, as

  11. Screening the budding yeast genome reveals unique factors affecting K2 toxin susceptibility.

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    Servienė, Elena; Lukša, Juliana; Orentaitė, Irma; Lafontaine, Denis L J; Urbonavičius, Jaunius

    2012-01-01

    Understanding how biotoxins kill cells is of prime importance in biomedicine and the food industry. The budding yeast (S. cerevisiae) killers serve as a convenient model to study the activity of biotoxins consistently supplying with significant insights into the basic mechanisms of virus-host cell interactions and toxin entry into eukaryotic target cells. K1 and K2 toxins are active at the cell wall, leading to the disruption of the plasma membrane and subsequent cell death by ion leakage. K28 toxin is active in the cell nucleus, blocking DNA synthesis and cell cycle progression, thereby triggering apoptosis. Genome-wide screens in the budding yeast S. cerevisiae identified several hundred effectors of K1 and K28 toxins. Surprisingly, no such screen had been performed for K2 toxin, the most frequent killer toxin among industrial budding yeasts. We conducted several concurrent genome-wide screens in S. cerevisiae and identified 332 novel K2 toxin effectors. The effectors involved in K2 resistance and hypersensitivity largely map in distinct cellular pathways, including cell wall and plasma membrane structure/biogenesis and mitochondrial function for K2 resistance, and cell wall stress signaling and ion/pH homeostasis for K2 hypersensitivity. 70% of K2 effectors are different from those involved in K1 or K28 susceptibility. Our work demonstrates that despite the fact that K1 and K2 toxins share some aspects of their killing strategies, they largely rely on different sets of effectors. Since the vast majority of the host factors identified here is exclusively active towards K2, we conclude that cells have acquired a specific K2 toxin effectors set. Our work thus indicates that K1 and K2 have elaborated different biological pathways and provides a first step towards the detailed characterization of K2 mode of action.

  12. Alteration of yeast activity by gamma radiation

    International Nuclear Information System (INIS)

    Chacharkar, M.P.; Tak, B.B.; Bhati, J.

    1996-01-01

    Yeast is an important component in microbe based industrial technologies. Due to the techno-economic reasons, the fermentation technique has acquired renewed interest. The effect of γ-radiation on the fermentation reaction has been investigated. The studies show that exposure of the fermentation mixture to γ-radiation at 5 kGy enhance alcohol production, whereas irradiation at higher doses, viz., 10 kGy and 25 kGy caused a considerable reduction in the alcohol yield. Therefore, low dose irradiation of fermentation mixtures can be applied for increasing the alcohol production by about 25%. (author). 13 refs., 1 fig

  13. Does Probiotic Yeast Act as Antigenotoxin?

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    Jekabs Raipulis

    2005-01-01

    Full Text Available The effect of probiotic yeast Saccharomyces boulardii on genotoxicity induced by the well-known mutagen 4-nitroquinoline-N-oxide (4-NQO, as well as antibacterial (furazolidone and antibiotic (nalidixic acid drugs, has been studied using the short-term bacterial assay, SOS chromotest, with Escherichia coli PQ 37 as the test organism. It has been shown that S. boulardii possesses antigenotoxic activity, revealed by SOS chromotest, when coincubated with these genotoxins. A weaker antigenotoxic activity against the same compounds was observed with S. carlsbergensis, too.

  14. Replication dynamics of the yeast genome.

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    Raghuraman, M K; Winzeler, E A; Collingwood, D; Hunt, S; Wodicka, L; Conway, A; Lockhart, D J; Davis, R W; Brewer, B J; Fangman, W L

    2001-10-05

    Oligonucleotide microarrays were used to map the detailed topography of chromosome replication in the budding yeast Saccharomyces cerevisiae. The times of replication of thousands of sites across the genome were determined by hybridizing replicated and unreplicated DNAs, isolated at different times in S phase, to the microarrays. Origin activations take place continuously throughout S phase but with most firings near mid-S phase. Rates of replication fork movement vary greatly from region to region in the genome. The two ends of each of the 16 chromosomes are highly correlated in their times of replication. This microarray approach is readily applicable to other organisms, including humans.

  15. Enhancing the performance of brewing yeasts.

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    Karabín, Marcel; Jelínek, Lukáš; Kotrba, Pavel; Cejnar, Rudolf; Dostálek, Pavel

    2017-12-22

    Beer production is one of the oldest known traditional biotechnological processes, but is nowadays facing increasing demands not only for enhanced product quality, but also for improved production economics. Targeted genetic modification of a yeast strain is one way to increase beer quality and to improve the economics of beer production. In this review we will present current knowledge on traditional approaches for improving brewing strains and for rational metabolic engineering. These research efforts will, in the near future, lead to the development of a wider range of industrial strains that should increase the diversity of commercial beers. Copyright © 2018 Elsevier Inc. All rights reserved.

  16. mRNA processing in yeast

    International Nuclear Information System (INIS)

    Stevens, A.

    1982-01-01

    Investigations in this laboratory center on basic enzymatic reactions of RNA. Still undefined are reactions involved in the conversion of precursors of mRA (pre-mRNA) to mRNA in eukaryotes. The pre-mRNA is called heterogeneous nuclear RNA and is 2 to 6 times larger than mRNA. The conversion, called splicing, involves a removal of internal sequences called introns by endoribonuclease action followed by a rejoining of the 3'- and 5'-end fragments, called exons, by ligating activity. It has not been possible yet to study the enzymes involved in vitro. Also undefined are reactions involved in the turnover or discarding of certain of the pre-mRNA molecules. Yeast is a simple eukaryote and may be expected to have the same, but perhaps simpler, processing reactions as the higher eukaryotes. Two enzymes involved in the processing of pre-mRNA and mRNA in yeast are under investigation. Both enzymes have been partially purified from ribonucleoprotein particles of yeast. The first is a unique decapping enzyme which cleaves [ 3 H]m 7 Gppp [ 14 C]RNA-poly (A) of yeast, yielding [ 3 H]m 7 GDP and is suggested by the finding that the diphosphate product, m 7 GpppA(G), and UDP-glucose are not hydrolyzed. The second enzyme is an endoribonuclease which converts both the [ 3 H] and [ 14 C] labels of [ 3 H]m 7 Gppp[ 14 C]RNA-poly(A) from an oligo(dT)-cellulose bound form to an unbound, acid-insoluble form. Results show that the stimulation involves an interaction of the labeled RNA with the small nuclear RNA. The inhibition of the enzyme by ethidium bromide and its stimulation by small nuclear RNA suggest that it may be a processing ribonuclease, requiring specific double-stranded features in its substrate. The characterization of the unique decapping enzyme and endoribonuclease may help to understand reactions involved in the processing of pre-mRNA and mRNA in eukaryotes

  17. Chromosomal Aneuploidy Improves the Brewing Characteristics of Sake Yeast.

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    Kadowaki, Masafumi; Fujimaru, Yuki; Taguchi, Seiga; Ferdouse, Jannatul; Sawada, Kazutaka; Kimura, Yuta; Terasawa, Yohei; Agrimi, Gennaro; Anai, Toyoaki; Noguchi, Hideki; Toyoda, Atsushi; Fujiyama, Asao; Akao, Takeshi; Kitagaki, Hiroshi

    2017-12-15

    The effect of chromosomal aneuploidy on the brewing characteristics of brewery yeasts has not been studied. Here we report that chromosomal aneuploidy in sake brewery yeast ( Saccharomyces cerevisiae ) leads to the development of favorable brewing characteristics. We found that pyruvate-underproducing sake yeast, which produces less off-flavor diacetyl, is aneuploid and trisomic for chromosomes XI and XIV. To confirm that this phenotype is due to aneuploidy, we obtained 45 haploids with various chromosomal additions and investigated their brewing profiles. A greater number of chromosomes correlated with a decrease in pyruvate production. Especially, sake yeast haploids with extra chromosomes in addition to chromosome XI produced less pyruvate than euploids. Mitochondrion-related metabolites and intracellular oxygen species in chromosome XI aneuploids were higher than those in euploids, and this effect was canceled in their "petite" strains, suggesting that an increase in chromosomes upregulated mitochondrial activity and decreased pyruvate levels. These findings suggested that an increase in chromosome number, including chromosome XI, in sake yeast haploids leads to pyruvate underproduction through the augmentation of mitochondrial activity. This is the first report proposing that aneuploidy in brewery yeasts improves their brewing profile. IMPORTANCE Chromosomal aneuploidy has not been evaluated in development of sake brewing yeast strains. This study shows the relationship between chromosomal aneuploidy and brewing characteristics of brewery yeast strains. High concentrations of pyruvate during sake storage give rise to α-acetolactate and, in turn, to high concentrations of diacetyl, which is considered an off-flavor. It was demonstrated that pyruvate-underproducing sake yeast is trisomic for chromosome XI and XIV. Furthermore, sake yeast haploids with extra chromosomes produced reduced levels of pyruvate and showed metabolic processes characteristic of

  18. The control of translational accuracy is a determinant of healthy ageing in yeast.

    Science.gov (United States)

    von der Haar, Tobias; Leadsham, Jane E; Sauvadet, Aimie; Tarrant, Daniel; Adam, Ilectra S; Saromi, Kofo; Laun, Peter; Rinnerthaler, Mark; Breitenbach-Koller, Hannelore; Breitenbach, Michael; Tuite, Mick F; Gourlay, Campbell W

    2017-01-01

    Life requires the maintenance of molecular function in the face of stochastic processes that tend to adversely affect macromolecular integrity. This is particularly relevant during ageing, as many cellular functions decline with age, including growth, mitochondrial function and energy metabolism. Protein synthesis must deliver functional proteins at all times, implying that the effects of protein synthesis errors like amino acid misincorporation and stop-codon read-through must be minimized during ageing. Here we show that loss of translational accuracy accelerates the loss of viability in stationary phase yeast. Since reduced translational accuracy also reduces the folding competence of at least some proteins, we hypothesize that negative interactions between translational errors and age-related protein damage together overwhelm the cellular chaperone network. We further show that multiple cellular signalling networks control basal error rates in yeast cells, including a ROS signal controlled by mitochondrial activity, and the Ras pathway. Together, our findings indicate that signalling pathways regulating growth, protein homeostasis and energy metabolism may jointly safeguard accurate protein synthesis during healthy ageing. © 2017 The Authors.

  19. Gis1 and Rph1 regulate glycerol and acetate metabolism in glucose depleted yeast cells.

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    Jakub Orzechowski Westholm

    Full Text Available Aging in organisms as diverse as yeast, nematodes, and mammals is delayed by caloric restriction, an effect mediated by the nutrient sensing TOR, RAS/cAMP, and AKT/Sch9 pathways. The transcription factor Gis1 functions downstream of these pathways in extending the lifespan of nutrient restricted yeast cells, but the mechanisms involved are still poorly understood. We have used gene expression microarrays to study the targets of Gis1 and the related protein Rph1 in different growth phases. Our results show that Gis1 and Rph1 act both as repressors and activators, on overlapping sets of genes as well as on distinct targets. Interestingly, both the activities and the target specificities of Gis1 and Rph1 depend on the growth phase. Thus, both proteins are associated with repression during exponential growth, targeting genes with STRE or PDS motifs in their promoters. After the diauxic shift, both become involved in activation, with Gis1 acting primarily on genes with PDS motifs, and Rph1 on genes with STRE motifs. Significantly, Gis1 and Rph1 control a number of genes involved in acetate and glycerol formation, metabolites that have been implicated in aging. Furthermore, several genes involved in acetyl-CoA metabolism are downregulated by Gis1.

  20. Glucose-based microbial production of the hormone melatonin in yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    Germann, Susanne M; Baallal Jacobsen, Simo A; Schneider, Konstantin; Harrison, Scott J; Jensen, Niels B; Chen, Xiao; Stahlhut, Steen G; Borodina, Irina; Luo, Hao; Zhu, Jiangfeng; Maury, Jérôme; Forster, Jochen

    2016-05-01

    Melatonin is a natural mammalian hormone that plays an important role in regulating the circadian cycle in humans. It is a clinically effective drug exhibiting positive effects as a sleep aid and a powerful antioxidant used as a dietary supplement. Commercial melatonin production is predominantly performed by complex chemical synthesis. In this study, we demonstrate microbial production of melatonin and related compounds, such as serotonin and N-acetylserotonin. We generated Saccharomyces cerevisiae strains that comprise heterologous genes encoding one or more variants of an L-tryptophan hydroxylase, a 5-hydroxy-L-tryptophan decarboxylase, a serotonin acetyltransferase, an acetylserotonin O-methyltransferase, and means for providing the cofactor tetrahydrobiopterin via heterologous biosynthesis and recycling pathways. We thereby achieved de novo melatonin biosynthesis from glucose. We furthermore accomplished increased product titers by altering expression levels of selected pathway enzymes and boosting co-factor supply. The final yeast strain produced melatonin at a titer of 14.50 ± 0.57 mg L(-1) in a 76h fermentation using simulated fed-batch medium with glucose as sole carbon source. Our study lays the basis for further developing a yeast cell factory for biological production of melatonin. © 2015 The Authors. Biotechnology Journal published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.