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D'Alessio Y, D'Alfonso A, Camilloni G. Chromatin conformations of HSP12 during transcriptional activation in the Saccharomyces cerevisiae stationary phase. Adv Biol Regul 2023; 90:100986. [PMID: 37741159 DOI: 10.1016/j.jbior.2023.100986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 08/17/2023] [Accepted: 09/16/2023] [Indexed: 09/25/2023]
Abstract
During evolution, living cells have developed sophisticated molecular and physiological processes to cope with a variety of stressors. These mechanisms, which collectively constitute the Environmental Stress Response, involve the activation/repression of hundreds of genes that are regulated to respond rapidly and effectively to protect the cell. The main stressors include sudden increases in environmental temperature and osmolarity, exposure to heavy metals, nutrient limitation, ROS accumulation, and protein-damaging events. The growth stages of the yeast S. cerevisiae proceed from the exponential to the diauxic phase, finally reaching the stationary phase. It is in this latter phase that the main stressor events are more active. In the present work, we aim to understand whether the responses evoked by the sudden onset of a stressor, like what happens to cells going through the stationary phase, would be different or similar to those induced by a gradual increase in the same stimulus. To this aim, we studied the expression of the HSP12 gene of the HSP family of proteins, typically induced by stress conditions, with a focus on the role of chromatin in this regulation. Analyses of nucleosome occupancy and three-dimensional chromatin conformation suggest the activation of a different response pathway upon a sudden vs a gradual onset of a stress stimulus. Here we show that it is the three-dimensional chromatin structure of HSP12, rather than nucleosome remodeling, that becomes altered in HSP12 transcription during the stationary phase.
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Affiliation(s)
- Yuri D'Alessio
- Dipartimento di Biologia e Biotecnologie, University of Rome, Sapienza Piazzale A. Moro 5, 00185, Rome, Italy.
| | - Anna D'Alfonso
- Dipartimento di Biologia e Biotecnologie, University of Rome, Sapienza Piazzale A. Moro 5, 00185, Rome, Italy.
| | - Giorgio Camilloni
- Dipartimento di Biologia e Biotecnologie, University of Rome, Sapienza Piazzale A. Moro 5, 00185, Rome, Italy.
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Abstract
Mitogen-activated protein kinases (MAPKs) regulate a variety of cellular processes in eukaryotes. In fungal pathogens, conserved MAPK pathways control key virulence functions such as infection-related development, invasive hyphal growth, or cell wall remodeling. Recent findings suggest that ambient pH acts as a key regulator of MAPK-mediated pathogenicity, but the underlying molecular events are unknown. Here, we found that in the fungal pathogen Fusarium oxysporum, pH controls another infection-related process, hyphal chemotropism. Using the ratiometric pH sensor pHluorin we show that fluctuations in cytosolic pH (pHc) induce rapid reprogramming of the three conserved MAPKs in F. oxysporum, and that this response is conserved in the fungal model organism Saccharomyces cerevisiae. Screening of a subset of S. cerevisiae mutants identified the sphingolipid-regulated AGC kinase Ypk1/2 as a key upstream component of pHc-modulated MAPK responses. We further show that acidification of the cytosol in F. oxysporum leads to an increase of the long-chain base (LCB) sphingolipid dihydrosphingosine (dhSph) and that exogenous addition of dhSph activates Mpk1 phosphorylation and chemotropic growth. Our results reveal a pivotal role of pHc in the regulation of MAPK signaling and suggest new ways to target fungal growth and pathogenicity. IMPORTANCE Fungal phytopathogens cause devastating losses in global agriculture. All plant-infecting fungi use conserved MAPK signaling pathways to successfully locate, enter, and colonize their hosts. In addition, many pathogens also manipulate the pH of the host tissue to increase their virulence. Here, we establish a functional link between cytosolic pH (pHc) and MAPK signaling in the control of pathogenicity in the vascular wilt fungal pathogen Fusarium oxysporum. We demonstrate that fluctuations in pHc cause rapid reprogramming of MAPK phosphorylation, which directly impacts key processes required for infection, such as hyphal chemotropism and invasive growth. Targeting pHc homeostasis and MAPK signaling can thus open new ways to combat fungal infection.
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Active Learning: A Shift from Passive Learning to Student Engagement Improves Understanding and Contextualization of Nutrition and Community Health. EDUCATION SCIENCES 2022. [DOI: 10.3390/educsci12070430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Challenging the notion of “teaching by telling,” active learning utilizes a student-oriented approach by emphasizing the concept of knowledge retention through peer interaction. To further examine the potential of active learning, we created a workshop based on didactic education and student collaboration. Participants included undergraduate students from traditionally underrepresented and disadvantaged backgrounds. The workshop was part of our summer academic enrichment program run in an urban, medically underserved community. The workshop focused on clinical and biochemical nutrition, wherein students synthesized information by discussing dietary choices and the socioeconomic aspects of nutrition. Student reception of the workshop was adjudged by anonymous surveys. The survey questions were designed to gauge how the workshop objectives were achieved. Cronbach alpha (0.276) confirmed that there was more than a single theme contained in the questions. The majority of students (97%) agreed that the workshop met the learning objectives: (1) acquire basic clinical knowledge, (2) gain a better understanding of nutrition, (3) formulate a linkage between clinical nutrition and disease, and (4) benefit from peer interaction. Students’ performance in the post-quiz (100% correct answers) had improved significantly compared to the pre-quiz (25% correct answers) suggesting acquisition, understanding and application of nutrition aspects taught in the workshop. Overall, the present study demonstrated the engagement and understanding of students with respect to learning about nutrition and community health in an active learning setting. These types of active-learning-based sessions may have broad applicability for any academic discipline to improve student engagement and knowledge retention.
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Menon AM, Dakal TC. Genomic scanning of the promoter sequence in osmo/halo-tolerance related QTLs in Zygosaccharomyces rouxii. Meta Gene 2020. [DOI: 10.1016/j.mgene.2020.100809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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Abstract
Bioethanol is the largest biotechnology product and the most dominant biofuel globally. Saccharomyces cerevisiae is the most favored microorganism employed for its industrial production. However, obtaining maximum yields from an ethanol fermentation remains a technical challenge, since cellular stresses detrimentally impact on the efficiency of yeast cell growth and metabolism. Ethanol fermentation stresses potentially include osmotic, chaotropic, oxidative, and heat stress, as well as shifts in pH. Well-developed stress responses and tolerance mechanisms make S. cerevisiae industrious, with bioprocessing techniques also being deployed at industrial scale for the optimization of fermentation parameters and the effective management of inhibition issues. Overlap exists between yeast responses to different forms of stress. This review outlines yeast fermentation stresses and known mechanisms conferring stress tolerance, with their further elucidation and improvement possessing the potential to improve fermentation efficiency.
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Novel endogenous promoters for genetic engineering of the marine microalga Nannochloropsis gaditana CCMP526. ALGAL RES 2019. [DOI: 10.1016/j.algal.2019.101708] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Abstract
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 transcriptional response of fission yeast cells to elevated levels of hydrogen peroxide. Particular attention is paid to the mechanisms that yeast cells employ to promote cell survival in conditions of intermediate and acute oxidative stress. The role of the Sty1/Spc1/Phh1 mitogen-activated protein kinase in regulating gene expression at multiple levels is discussed in detail.
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Affiliation(s)
- Manos A Papadakis
- a Center for Biological Sequence Analysis, Department of Systems Biology, Technical University of Denmark , Lyngby , Denmark
| | - Christopher T Workman
- a Center for Biological Sequence Analysis, Department of Systems Biology, Technical University of Denmark , Lyngby , Denmark
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Henke C, Jung EM, Voit A, Kothe E, Krause K. Dehydrogenase genes in the ectomycorrhizal fungus Tricholoma vaccinum: A role for Ald1 in mycorrhizal symbiosis. J Basic Microbiol 2015; 56:162-74. [PMID: 26344933 DOI: 10.1002/jobm.201500381] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 08/19/2015] [Indexed: 11/07/2022]
Abstract
Ectomycorrhizal symbiosis is important for forest ecosystem functioning with tree-fungal cooperation increasing performance and countering stress conditions. Aldehyde dehydrogenases (ALDHs) are key enzymes for detoxification and thus may play a role in stress response of the symbiotic association. With this focus, eight dehydrogenases, Ald1 through Ald7 and TyrA, of the ectomycorrhizal basidiomycete Tricholoma vaccinum were characterized and phylogenetically investigated. Functional analysis was performed through differential expression analysis by feeding different, environmentally important substances. A strong effect of indole-3-acetic acid (IAA) was identified, linking mycorrhiza formation and auxin signaling between the symbiosis partners. We investigated ald1 overexpressing strains for performance in mycorrhiza with the host tree spruce (Picea abies) and observed an increased width of the apoplast, accommodating the Hartig' net hyphae of the T. vaccinum over-expressing transformants. The results support a role for Ald1 in ectomycorrhiza formation and underline functional differentiation within fungal aldehyde dehydrogenases in the family 1 of ALDHs.
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Affiliation(s)
- Catarina Henke
- Institute of Microbiology, Friedrich Schiller University Jena, Microbial Communication, Jena, Germany
| | - Elke-Martina Jung
- Institute of Microbiology, Friedrich Schiller University Jena, Microbial Communication, Jena, Germany
| | - Annekatrin Voit
- Institute of Microbiology, Friedrich Schiller University Jena, Microbial Communication, Jena, Germany
| | - Erika Kothe
- Institute of Microbiology, Friedrich Schiller University Jena, Microbial Communication, Jena, Germany
| | - Katrin Krause
- Institute of Microbiology, Friedrich Schiller University Jena, Microbial Communication, Jena, Germany
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Wallace-Salinas V, Brink DP, Ahrén D, Gorwa-Grauslund MF. Cell periphery-related proteins as major genomic targets behind the adaptive evolution of an industrial Saccharomyces cerevisiae strain to combined heat and hydrolysate stress. BMC Genomics 2015; 16:514. [PMID: 26156140 PMCID: PMC4496855 DOI: 10.1186/s12864-015-1737-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 06/29/2015] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Laboratory evolution is an important tool for developing robust yeast strains for bioethanol production since the biological basis behind combined tolerance requires complex alterations whose proper regulation is difficult to achieve by rational metabolic engineering. Previously, we reported on the evolved industrial Saccharomyces cerevisiae strain ISO12 that had acquired improved tolerance to grow and ferment in the presence of lignocellulose-derived inhibitors at high temperature (39 °C). In the current study, we used comparative genomics to uncover the extent of the genomic alterations that occurred during the evolution process and investigated possible associations between the mutations and the phenotypic traits in ISO12. RESULTS Through whole-genome sequencing and variant calling we identified a high number of strain-unique SNPs and INDELs in both ISO12 and the parental strain Ethanol Red. The variants were predicted to have 760 non-synonymous effects in both strains combined and were significantly enriched in Gene Ontology terms related to cell periphery, membranes and cell wall. Eleven genes, including MTL1, FLO9/FLO11, and CYC3 were found to be under positive selection in ISO12. Additionally, the FLO genes exhibited changes in copy number, and the alterations to this gene family were correlated with experimental results of multicellularity and invasive growth in the adapted strain. An independent lipidomic analysis revealed further differences between the strains in the content of nine lipid species. Finally, ISO12 displayed improved viability in undiluted spruce hydrolysate that was unrelated to reduction of inhibitors and changes in cell wall integrity, as shown by HPLC and lyticase assays. CONCLUSIONS Together, the results of the sequence comparison and the physiological characterisations indicate that cell-periphery proteins (e.g. extracellular sensors such as MTL1) and peripheral lipids/membranes are important evolutionary targets in the process of adaptation to the combined stresses. The capacity of ISO12 to develop complex colony formation also revealed multicellularity as a possible evolutionary strategy to improve competitiveness and tolerance to environmental stresses (also reflected by the FLO genes). Although a panel of altered genes with high relevance to the novel phenotype was detected, this study also demonstrates that the observed long-term molecular effects of thermal and inhibitor stress have polygenetic basis.
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Affiliation(s)
- Valeria Wallace-Salinas
- Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, Lund, SE-22100, Sweden.
| | - Daniel P Brink
- Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, Lund, SE-22100, Sweden.
| | - Dag Ahrén
- Microbial Ecology Group, Department of Biology, Lund University, Ecology Building, Lund, Sweden.
| | - Marie F Gorwa-Grauslund
- Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, Lund, SE-22100, Sweden.
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Asiimwe T, Krause K, Schlunk I, Kothe E. Modulation of ethanol stress tolerance by aldehyde dehydrogenase in the mycorrhizal fungus Tricholoma vaccinum. MYCORRHIZA 2012; 22:471-484. [PMID: 22159964 DOI: 10.1007/s00572-011-0424-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 11/25/2011] [Indexed: 05/28/2023]
Abstract
We report the first mycorrhizal fungal aldehyde dehydrogenase gene, ald1, which was isolated from the basidiomycete Tricholoma vaccinum. The gene, encoding a protein Ald1 of 502 amino acids, is up-regulated in ectomycorrhiza. Phylogenetic analyses using 53 specific fungal aldehyde dehydrogenases from all major phyla in the kingdom of fungi including Ald1 and two partial sequences of T. vaccinum were performed to get an insight in the evolution of the aldehyde dehydrogenase family. By using competitive and real-time RT-PCR, ald1 is up-regulated in response to alcohol and aldehyde-related stress. Furthermore, heterologous expression of ald1 in Escherichia coli and subsequent in vitro enzyme activity assay demonstrated the oxidation of propionaldehyde and butyraldehyde with different kinetics using either NAD(+) or NADP(+) as cofactors. In addition, overexpression of ald1 in T. vaccinum after Agrobacterium tumefaciens-mediated transformation increased ethanol stress tolerance. These results demonstrate the ability of Ald1 to circumvent ethanol stress, a critical function in mycorrhizal habitats.
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Affiliation(s)
- Theodore Asiimwe
- Institute of Microbiology, Friedrich Schiller University, Neugasse 25, 07743, Jena, Germany
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Bissoli G, Niñoles R, Fresquet S, Palombieri S, Bueso E, Rubio L, García-Sánchez MJ, Fernández JA, Mulet JM, Serrano R. Peptidyl-prolyl cis-trans isomerase ROF2 modulates intracellular pH homeostasis in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 70:704-716. [PMID: 22268595 DOI: 10.1111/j.1365-313x.2012.04921.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Intracellular pH must be kept close to neutrality to be compatible with cellular functions, but the mechanisms of pH homeostasis and the responses to intracellular acidification are mostly unknown. In the plant Arabidopsis thaliana, we found that intracellular acid stress generated by weak organic acids at normal external pH induces expression of several chaperone genes, including ROF2, which encodes a peptidyl-prolyl cis-trans isomerase of the FK506-binding protein class. Loss of function of ROF2, and especially double mutation of ROF2 and the closely related gene ROF1, results in acid sensitivity. Over-expression of ROF2 confers tolerance to intracellular acidification by increasing proton extrusion from cells. The activation of the plasma membrane proton pump (H(+) -ATPase) is indirect: over-expression of ROF2 activates K(+) uptake, causing depolarization of the plasma membrane, which activates the electrogenic H(+) pump. The depolarization of ROF2 over-expressing plants explains their tolerance to toxic cations such as lithium, norspermidine and hygromycin B, whose uptake is driven by the membrane potential. As ROF2 induction and intracellular acidification are common consequences of many stresses, this mechanism of pH homeostasis may be of general importance for stress tolerance.
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Affiliation(s)
- Gaetano Bissoli
- Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, Camino de Vera, Valencia, Spain
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Jariyachawalid K, Laowanapiban P, Meevootisom V, Wiyakrutta S. Effective enhancement of Pseudomonas stutzeri D-phenylglycine aminotransferase functional expression in Pichia pastoris by co-expressing Escherichia coli GroEL-GroES. Microb Cell Fact 2012; 11:47. [PMID: 22515657 PMCID: PMC3503884 DOI: 10.1186/1475-2859-11-47] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Accepted: 03/26/2012] [Indexed: 12/02/2022] Open
Abstract
Background D-phenylglycine aminotransferase (D-PhgAT) of Pseudomonas stutzeri ST-201 catalyzes the reversible stereo-inverting transamination potentially useful in the application for synthesis of D-phenylglycine and D-4-hydroxyphenylglycine using L-glutamate as a low cost amino donor substrate in one single step. The enzyme is a relatively hydrophobic homodimeric intracellular protein difficult to express in the soluble functionally active form. Over-expression of the dpgA gene in E. coli resulted in the majority of the D-PhgAT aggregated into insoluble inclusion bodies that failed to be re-natured. Expression in Pichia pastoris was explored as an alternative route for high level production of the D-PhgAT. Results Intracellular expression of the codon-optimized synthetic dpgA gene under the PAOX1 promoter in P. pastoris resulted in inactive D-PhgAT associated with insoluble cellular fraction and very low level of D-PhgAT activity in the soluble fraction. Manipulation of culture conditions such as addition of sorbitol to induce intracellular accumulation of osmolytes, addition of benzyl alcohol to induce chaperone expression, or lowering incubation temperature to slow down protein expression and folding rates all failed to increase the active D-PhgAT yield. Co-expression of E. coli chaperonins GroEL-GroES with the D-PhgAT dramatically improved the soluble active enzyme production. Increasing gene dosage of both the dpgA and those of the chaperones further increased functional D-PhgAT yield up to 14400-fold higher than when the dpgA was expressed alone. Optimization of cultivation condition further increased D-PhgAT activity yield from the best co-expressing strain by 1.2-fold. Conclusions This is the first report on the use of bacterial chaperones co-expressions to enhance functional intracellular expression of bacterial enzyme in P. pastoris. Only two bacterial chaperone genes groEL and groES were sufficient for dramatic enhancement of functionally active D-PhgAT expression in this yeast. With the optimized gene dosage and chaperone combinations, P. pastoris can be attractive for intracellular expression of bacterial proteins since it can grow to a very high cell density which is translated into the higher volumetric product yield than the E. coli or other bacterial systems.
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Affiliation(s)
- Kanidtha Jariyachawalid
- Department of Biotechnology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand
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Activation of two different resistance mechanisms in Saccharomyces cerevisiae upon exposure to octanoic and decanoic acids. Appl Environ Microbiol 2010; 76:7526-35. [PMID: 20851956 DOI: 10.1128/aem.01280-10] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Medium-chain fatty acids (octanoic and decanoic acids) are well known as fermentation inhibitors. During must fermentation, the toxicity of these fatty acids is enhanced by ethanol and low pH, which favors their entrance in the cell, resulting in a decrease of internal pH. We present here the characterization of the mechanisms involved in the establishment of the resistance to these fatty acids. The analysis of the transcriptome response to the exposure to octanoic and decanoic acids revealed that two partially overlapping mechanisms are activated; both responses share many genes with an oxidative stress response, but some key genes were activated differentially. The transcriptome response to octanoic acid stress can be described mainly as a weak acid response, and it involves Pdr12p as the main transporter. The phenotypic analysis of knocked-out strains confirmed the role of the Pdr12p transporter under the control of WAR1 but also revealed the involvement of the Tpo1p major facilitator superfamily proteins (MFS) transporter in octanoic acid expulsion. In contrast, the resistance to decanoic acid is composite. It also involves the transporter Tpo1p and includes the activation of several genes of the beta-oxidation pathway and ethyl ester synthesis. Indeed, the induction of FAA1 and EEB1, coding for a long-chain fatty acyl coenzyme A synthetase and an alcohol acyltransferase, respectively, suggests a detoxification pathway through the production of decanoate ethyl ester. These results are confirmed by the sensitivity of strains bearing deletions for the transcription factors encoded by PDR1, STB5, OAF1, and PIP2 genes.
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Cell de-energization prevents plasmid transformation of yeast Saccharomyces cerevisiae: evidence for the requirement of ATP. Open Life Sci 2010. [DOI: 10.2478/s11535-009-0072-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
AbstractThe dependence of the yeast Saccharomyces cerevisiae transformation on energy requirement was studied. The inhibitory effect of sodium arsenate, used for the depletion of the intracellular ATP pool, was determined. Incubation of the yeast cells in 5 mM sodium arsenate diminished ATP accumulation by 50% and the transformation efficiency decreased by 65%. To discriminate between ATP produced by substrate level phosphorylation and oxidative phosphorylation, the inhibitory analysis of a mutant with defective mitochondria was performed. Sodium fluoride (10–50 mM), as inhibitor of glycolysis, elicited a concentration-dependent decrease in intracellular ATP levels in both parental and mutant cells. The equal transformation efficiency of the mitochondrial mutant and parental strain, in addition to experiments with oligomycin, demonstrated the independence of plasmid transformation on mitochondrial ATP synthesis. This is consistent with our hypothesis that yeast transformation efficiency is associated with ATP produced by substrate level phosphorylation.
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Schüller C, Mamnun YM, Wolfger H, Rockwell N, Thorner J, Kuchler K. Membrane-active compounds activate the transcription factors Pdr1 and Pdr3 connecting pleiotropic drug resistance and membrane lipid homeostasis in saccharomyces cerevisiae. Mol Biol Cell 2007; 18:4932-44. [PMID: 17881724 PMCID: PMC2096591 DOI: 10.1091/mbc.e07-06-0610] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The Saccharomyces cerevisiae zinc cluster transcription factors Pdr1 and Pdr3 mediate general drug resistance to many cytotoxic substances also known as pleiotropic drug resistance (PDR). The regulatory mechanisms that activate Pdr1 and Pdr3 in response to the various xenobiotics are poorly understood. In this study, we report that exposure of yeast cells to 2,4-dichlorophenol (DCP), benzyl alcohol, nonionic detergents, and lysophospholipids causes rapid activation of Pdr1 and Pdr3. Furthermore, Pdr1/Pdr3 target genes encoding the ATP-binding cassette proteins Pdr5 and Pdr15 confer resistance against these compounds. Genome-wide transcript analysis of wild-type and pdr1Delta pdr3Delta cells treated with DCP reveals most prominently the activation of the PDR response but also other stress response pathways. Polyoxyethylene-9-laurylether treatment produced a similar profile with regard to activation of Pdr1 and Pdr3, suggesting activation of these by detergents. The Pdr1/Pdr3 response element is sufficient to confer regulation to a reporter gene by these substances in a Pdr1/Pdr3-dependent manner. Our data indicate that compounds with potential membrane-damaging or -perturbing effects might function as an activating signal for Pdr1 and Pdr3, and they suggest a role for their target genes in membrane lipid organization or remodeling.
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Affiliation(s)
- Christoph Schüller
- *Medical University Vienna, Max F. Perutz Laboratories, Department of Medical Biochemistry, A-1030 Vienna, Austria; and
| | - Yasmine M. Mamnun
- *Medical University Vienna, Max F. Perutz Laboratories, Department of Medical Biochemistry, A-1030 Vienna, Austria; and
| | - Hubert Wolfger
- *Medical University Vienna, Max F. Perutz Laboratories, Department of Medical Biochemistry, A-1030 Vienna, Austria; and
| | - Nathan Rockwell
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720
| | - Jeremy Thorner
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720
| | - Karl Kuchler
- *Medical University Vienna, Max F. Perutz Laboratories, Department of Medical Biochemistry, A-1030 Vienna, Austria; and
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Cowart LA, Hannun YA. Selective Substrate Supply in the Regulation of Yeast de Novo Sphingolipid Synthesis. J Biol Chem 2007; 282:12330-40. [PMID: 17322298 DOI: 10.1074/jbc.m700685200] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The heat stress response of Saccharomyces cerevisiae is characterized by transient cell cycle arrest, altered gene expression, degradation of nutrient permeases, trehalose accumulation, and translation initiation of heat shock proteins. Importantly heat stress also induces de novo sphingolipid synthesis upon which many of these subprograms of the heat stress response depend. Despite extensive data addressing the roles for sphingolipids in heat stress, the mechanism(s) by which heat induces sphingolipid synthesis remains unknown. This study was undertaken to determine the events and/or factors required for heat stress-induced sphingolipid synthesis. Data presented indicate that heat does not directly alter the in vitro activity of serine palmitoyltransferase (SPT), the enzyme responsible for initiating de novo sphingolipid synthesis. Moreover deletion of the small peptide Tsc3p, which is thought to maximize SPT activity, specifically reduced production of C(20) sphingolipid species by over 70% but did not significantly decrease overall sphingoid base production. In contrast, the fatty-acid synthase inhibitor cerulenin nearly completely blocked sphingoid base production after heat, indicating a requirement for endogenous fatty acids for heat-mediated sphingoid base synthesis. Consistent with this, genetic studies show that fatty acid import does not contribute to heat-induced de novo synthesis under normal conditions. Interestingly the absence of medium serine also ameliorated heat-induced sphingoid base production, indicating a requirement for exogenous serine for the response, and consistent with this finding, disruption of synthesis of endogenous serine did not affect heat-induced sphingolipid synthesis. Serine uptake assays indicated that heat increased serine uptake from medium by 100% during the first 10 min of heat stress. Moreover treatments that increase serine uptake in the absence of heat including acute medium acidification and glucose treatment also enhanced de novo sphingoid base synthesis equivalent to that induced by heat stress. These data agree with findings from mammalian systems that availability of substrates is a key determinant of flux through sphingolipid synthesis. Moreover data presented here indicate that SPT activity can be driven by several factors that increase serine uptake in the absence of heat. These findings may provide insights into the many systems in which de novo synthesis is increased in the absence of elevated in vitro SPT activity.
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Affiliation(s)
- L Ashley Cowart
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina , Charleston, South Carolina 29425, USA
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Sánchez B, de los Reyes-Gavilán CG, Margolles A. The F1F0-ATPase of Bifidobacterium animalis is involved in bile tolerance. Environ Microbiol 2006; 8:1825-33. [PMID: 16958763 DOI: 10.1111/j.1462-2920.2006.01067.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Adaptation and tolerance to bile stress are important factors for the survival of bifidobacteria in the intestinal tract. Bifidobacterium animalis is a probiotic microorganism which has been largely applied in fermented dairy foods due to its technological properties and its health-promoting effects for humans. The effect of the presence of bile on the activity and expression of F(1)F(0)-ATPase, the pool of ATP and the intracellular pH of B. animalis IPLA 4549 and its mutant with acquired resistance to bile B. animalis 4549dOx was determined. The bile-resistant mutant tolerated the acid pH better than its parent strain. Bile induced the expression of the F(1)F(0)-ATPase and increased the membrane-bound H(+)-ATPase activity, in both parent and mutant strains. In acidic conditions (pH 5.0), the expression and the activity of this enzyme were higher in the mutant than in the parent strain when cells were grown in the absence of bile. Total ATP content was higher for the mutant in the absence of bile, whereas the presence of bile induced a decrease of intracellular ATP levels, which was much more pronounced for the parent strain. At pH 4.0, and independently on the presence or absence of bile, the mutant showed a higher intracellular pH than its parent strain. These findings suggest that the bile-adapted B. animalis strain is able to tolerate bile by increasing the intracellular ATP reserve, and by inducing proton pumping by the F(1)F(0)-ATPase, therefore tightly regulating the internal pH, and provide a link between the physiological state of the cell and the response to bile.
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Affiliation(s)
- Borja Sánchez
- Instituto de Productos Lácteos de Asturias, Consejo Superior de Investigaciones Científicas (CSIC), Ctra. Infiesto s/n, 33300, Villaviciosa, Asturias, Spain
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18
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Schmitt M, Schwanewilm P, Ludwig J, Lichtenberg-Fraté H. Use of PMA1 as a housekeeping biomarker for assessment of toxicant-induced stress in Saccharomyces cerevisiae. Appl Environ Microbiol 2006; 72:1515-22. [PMID: 16461706 PMCID: PMC1392943 DOI: 10.1128/aem.72.2.1515-1522.2006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2005] [Accepted: 11/18/2005] [Indexed: 11/20/2022] Open
Abstract
The brewer's yeast Saccharomyces cerevisiae has emerged as a versatile and robust model system for laboratory use to study toxic effects of various substances. In this study, toxicant-induced stresses of pure compounds were investigated in Saccharomyces cerevisiae utilizing a destabilized version of the green fluorescent protein optimized for expression in yeast (yEGFP3) under control of the promoter of the housekeeping plasma membrane ATPase gene PMA1. The responses of the biomarker upon increasing test compound concentrations were monitored by determining the decrease in fluorescence. The reporter assay deployed a simple and robust protocol for the rapid detection of toxic effects within a 96-well microplate format. Fluorescence emissions were normalized to cell growth determined by absorption and were correlated to internal reference standards. The results were expressed as effective concentrations (EC20). Dose-response experiments were conducted in which yeast cells were exposed in minimal medium and in the presence of 20% fetal calf serum to sublethal concentrations of an array of heavy metals, salt, and a number of stress-inducing compounds (Diclofenac, Lindane, methyl-N-nitro-N-nitrosoguanidine [MNNG], hydroxyurea, and caffeine). Long-term exposure (7 h) played a considerable role in the adaptive response to intoxication compared to early responses at 4 h exposure. The data obtained after 4 h of exposure and expressed as EC20 were compared to 50% inhibitory concentration values derived from cell line and ecotoxicological tests. This study demonstrates the versatility of the novel biomarker to complement existing test batteries to assess contaminant exposure and effects.
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Affiliation(s)
- Marcel Schmitt
- Institut für Zelluläre und Molekulare Botanik, AG Molekulare Bioenergetik, Universität Bonn, Kirschallee 1, 53115 Bonn, Germany
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19
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Claret S, Gatti X, Doignon F, Thoraval D, Crouzet M. The Rgd1p Rho GTPase-activating protein and the Mid2p cell wall sensor are required at low pH for protein kinase C pathway activation and cell survival in Saccharomyces cerevisiae. EUKARYOTIC CELL 2005; 4:1375-86. [PMID: 16087742 PMCID: PMC1214525 DOI: 10.1128/ec.4.8.1375-1386.2005] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The protein kinase C (PKC) pathway is involved in the maintenance of cell shape and cell integrity in Saccharomyces cerevisiae. Here, we show that this pathway mediates tolerance to low pH and that the Bck1 and Slt2 proteins belonging to the mitogen-activated protein kinase cascade are essential for cell survival at low pH. The PKC pathway is activated during acidification of the extracellular environment, and this activation depends mainly on the Mid2p cell wall sensor. Rgd1p, which encodes a Rho GTPase-activating protein for the small G proteins Rho3p and Rho4p, also plays a role in low-pH response. The rgd1Delta strain is sensitive to low pH, and Rgd1p activates the PKC pathway in an acidic environment. Inactivation of both genes in the double mutant rgd1Delta mid2Delta strain renders yeast cells unable to survive at low pH as in bck1Delta and slt2Delta strains. Our data provide evidence for the existence of two distinct ways, one involving Mid2p and the other involving Rgd1p, with both converging to the cell integrity pathway to mediate low-pH tolerance in Saccharomyces cerevisiae. Nevertheless, even if Rgd1p acts on the PKC pathway, it seems that its mediating action on low-pH tolerance is not limited to this pathway. As the Mid2p amount plays a role in rgd1Delta sensitivity to low pH, Mid2p seems to act more like a molecular rheostat, controlling the level of PKC pathway activity and thus allowing phenotypical expression of RGD1 inactivation.
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Affiliation(s)
- Sandra Claret
- Laboratoire de Biologie Moléculaire et de Séquençage, Institut de Biochimie et Génétique Cellulaires, UMR CNRS/Université Bordeaux 2, 5095, boite 64, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France
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20
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Vigh L, Escribá PV, Sonnleitner A, Sonnleitner M, Piotto S, Maresca B, Horváth I, Harwood JL. The significance of lipid composition for membrane activity: New concepts and ways of assessing function. Prog Lipid Res 2005; 44:303-44. [PMID: 16214218 DOI: 10.1016/j.plipres.2005.08.001] [Citation(s) in RCA: 176] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In the last decade or so, it has been realised that membranes do not just have a lipid-bilayer structure in which proteins are embedded or with which they associate. Structures are dynamic and contain areas of heterogeneity which are vital for their formation. In this review, we discuss some of the ways in which these dynamic and heterogeneous structures have implications during stress and in relation to certain human diseases. A particular stress is that of temperature which may instigate adaptation in poikilotherms or appropriate defensive responses during fever in mammals. Recent data emphasise the role of membranes in sensing temperature changes and in controlling a regulatory loop with chaperone proteins. This loop seems to need the existence of specific membrane microdomains and also includes association of chaperone (heat stress) proteins with the membrane. The role of microdomains is then discussed further in relation to various human pathologies such as cardiovascular disease, cancer and neurodegenerative diseases. The concept of modifying membrane lipids (lipid therapy) as a means for treating such pathologies is then introduced. Examples are given when such methods have been shown to have benefit. In order to study membrane microheterogeneity in detail and to elucidate possible molecular mechanisms that account for alteration in membrane function, new methods are needed. In the second part of the review, we discuss ultra-sensitive and ultra-resolution imaging techniques. These include atomic force microscopy, single particle tracking, single particle tracing and various modern fluorescence methods. Finally, we deal with computing simulation of membrane systems. Such methods include coarse-grain techniques and Monte Carlo which offer further advances into molecular dynamics. As computational methods advance they will have more application by revealing the very subtle interactions that take place between the lipid and protein components of membranes - and which are so essential to their function.
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Affiliation(s)
- Làszló Vigh
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, H-6726 Szeged, Hungary
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21
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Zakrzewska A, Boorsma A, Brul S, Hellingwerf KJ, Klis FM. Transcriptional response of Saccharomyces cerevisiae to the plasma membrane-perturbing compound chitosan. EUKARYOTIC CELL 2005; 4:703-15. [PMID: 15821130 PMCID: PMC1087819 DOI: 10.1128/ec.4.4.703-715.2005] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Chitosan is a plasma membrane-perturbing compound consisting of linear chains of beta-1,4-linked glucosamine residues, which at acidic pHs become positively charged. It is extensively used as an antimicrobial compound, yet its mode of action is still unresolved. Chitosan strongly affected the growth of the yeast Saccharomyces cerevisiae, the food spoilage yeast Zygosaccharomyces bailii, and two human-pathogenic yeasts, Candida albicans and Candida glabrata. Microarray analysis of yeast cells treated with sublethal concentrations of chitosan revealed induction of the environmental stress response and three more major transcriptional responses. The first was a rapid and stable Cin5p-mediated response. Cin5p/Yap4p is a transcription factor involved in various stress responses. Deletion of CIN5 led to increased chitosan sensitivity. The second was a Crz1p-mediated response, which is delayed compared to the Cin5p response. Crz1p is a transcription factor of the calcineurin pathway. Cells deleted for CRZ1 or treated with the calcineurin inhibitor FK506 became hypersensitive to chitosan, supporting the notion that the Crz1p-controlled response offers protection against chitosan. The third was a strong Rlm1p-mediated response which ran parallel in time with the Crz1p-regulated response. Rlm1p is a transcription factor of the cell wall integrity pathway, which is activated by cell wall stress. Importantly, chitosan-treated cells became more resistant to beta-1,3-glucanase, which is a well-known response to cell wall stress. We propose that the transcriptional response to chitosan may be representative of other plasma membrane-perturbing compounds.
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Affiliation(s)
- Anna Zakrzewska
- Molecular Microbial Physiology and Molecular Biology and Microbial Food Safety, Swammerdam Institute of Life Sciences, Amsterdam, The Netherlands.
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22
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Durchschlag E, Reiter W, Ammerer G, Schüller C. Nuclear localization destabilizes the stress-regulated transcription factor Msn2. J Biol Chem 2004; 279:55425-32. [PMID: 15502160 DOI: 10.1074/jbc.m407264200] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The transcriptional program of yeast cells undergoes dramatic changes during the shift from fermentative growth to respiratory growth. A large part of this response is mediated by the stress responsive transcription factor Msn2. During glucose exhaustion, Msn2 is activated and concentrated in the nucleus. Simultaneously, Msn2 protein levels also drop significantly under this condition. Here we show that the decrease in Msn2 concentration is due to its increased degradation. Moreover, Msn2 levels are also reduced under chronic stress or low protein kinase A (PKA) activity, both conditions that cause a predominant nuclear localization of Msn2. Similar effects were found in msn5 mutant cells that block Msn2 nuclear export. To approximate the effect of low PKA activity on Msn2, we generated a mutant form with alanine substitutions in PKA phosphorylation sites. High expression of this Msn2 mutant is detrimental for growth, suggesting that the increased degradation of nuclear Msn2 might be necessary to adapt cells to low PKA conditions after the diauxic shift or to allow growth under chronic stress conditions.
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Affiliation(s)
- Erich Durchschlag
- Institute of Biochemistry and Molecular Cell Biology and Ludwig Boltzmann Forschungsstelle for Biochemistry, Max F. Perutz Laboratories, University and BioCenter of Vienna, Dr. Bohr-Gasse 9/5, A-1030 Vienna, Austria
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23
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Hronská L, Mrózová Z, ValachoviÄ M, Hapala I. Low concentrations of the non-ionic detergent Nonidet P-40 interfere with sterol biogenesis and viability of the yeastSaccharomyces cerevisiae. FEMS Microbiol Lett 2004. [DOI: 10.1111/j.1574-6968.2004.tb09762.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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24
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Inouye M, Phadtare S. Cold shock response and adaptation at near-freezing temperature in microorganisms. Sci Signal 2004; 2004:pe26. [PMID: 15199224 DOI: 10.1126/stke.2372004pe26] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Microorganisms that naturally encounter sharp temperature shifts must develop strategies for responding and adapting to these shifts. Escherichia coli, which are adapted to living at both warm temperatures inside animals and cooler ambient temperatures, respond to low temperatures (10 degrees to 15 degrees C) by adjusting membrane lipid composition and increasing the production of proteins that act as "RNA chaperones" required for transcription and translation and proteins that facilitate ribosomal assembly. In contrast, yeast, which are adapted to cooler temperatures, show a relatively minor cold shock response after temperature shifts from 30 degrees to 10 degrees C but respond with a dramatic increase in the synthesis of trehalose and a heat shock protein when exposed to freezing or near-freezing temperatures. This emphasizes the fact that different groups of microorganisms exhibit distinct types of cold shock responses.
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Affiliation(s)
- Masayori Inouye
- Robert Wood Johnson Medical School, Department of Biochemistry, 675 Hoes Lane, Piscataway, NJ 08854, USA.
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25
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Krishnamurthy S, Plaine A, Albert J, Prasad T, Prasad R, Ernst JF. Dosage-dependent functions of fatty acid desaturase Ole1p in growth and morphogenesis of Candida albicans. Microbiology (Reading) 2004; 150:1991-2003. [PMID: 15184585 DOI: 10.1099/mic.0.27029-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Conditions in the infected human host trigger virulence attributes of the fungal pathogenCandida albicans. Specific inducers and elevated temperatures lead to hyphal development or regulate chlamydospore development. To explore if these processes are affected by membrane lipids, an investigation of the functions of the Ole1 fatty acid desaturase (stearoyl-CoA desaturase) inC. albicans, which synthesizes oleic acid, was undertaken. A conditional strain expressingOLE1from the regulatableMET3promoter was unable to grow in repressing conditions, indicating thatOLE1is an essential gene. In contrast, a mutant lacking both alleles ofOLE2, encoding a Ole1p homologue, was viable and had no apparent phenotypes. Partial repression ofMET3p–OLE1slightly lowered oleic acid levels and decreased membrane fluidity; these conditions permitted growth in the yeast form, but prevented hyphal development in aerobic conditions and blocked the formation of chlamydospores. In contrast, in hypoxic conditions, which trigger an alternative morphogenetic pathway, hyphal morphogenesis was unaffected. Because aerobic morphogenetic signalling and oleic acid biosynthesis require oxygen, it is proposed that oleic acid may function as a sensor activating specific morphogenetic pathways in normoxic conditions.
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Affiliation(s)
| | - Armêl Plaine
- Institut für Mikrobiologie, Heinrich-Heine-Universität, 40225 Düsseldorf, Germany
| | - Juliane Albert
- Institut für Mikrobiologie, Heinrich-Heine-Universität, 40225 Düsseldorf, Germany
| | - Tulika Prasad
- Jawaharlal Nehru University, New Delhi 110067, India
| | | | - Joachim F Ernst
- Institut für Mikrobiologie, Heinrich-Heine-Universität, 40225 Düsseldorf, Germany
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26
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Alejandre-Durán E, Roldán-Arjona T, Ariza RR, Ruiz-Rubio M. The photolyase gene from the plant pathogen Fusarium oxysporum f. sp. lycopersici is induced by visible light and alpha-tomatine from tomato plant. Fungal Genet Biol 2004; 40:159-65. [PMID: 14516768 DOI: 10.1016/s1087-1845(03)00089-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Survival of irradiated spores from Fusarium oxysporum with ultraviolet radiation (UV) was increased following exposition to visible light, indicating that this phytopathogenic fungus has a mechanism of photoreactivation able to counteract the lethal effects of UV. A genomic sequence containing the complete photolyase gene (phr1) from F. oxysporum was isolated by heterologous hybridisation with the Neurospora crassa photolyase gene. The F. oxysporum phr1 cDNA was isolated and expressed in a photolyase deficient Escherichia coli strain. The complementation of the photoreactivation deficiency of this E. coli mutant by phr1 cDNA demonstrated that the photolyase gene from F. oxysporum encodes a functional protein. The F. oxysporum PHR1 protein has a domain characteristic of photolyases from fungi (Trichoderma harziaium, N. crassa, Magnaporthe grisea, Saccharomyces cerevisiae) to bacteria (E. coli), and clusters in the photolyases phylogenetic tree with fungal photolyases. The F. oxysporum phr1 gene was inducible by visible light. The phr1 expression was also detected in presence of alpha-tomatine, a glycoalkaloid from tomato damaging cell membranes, suggesting that phr1 is induced by this cellular stress.
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Affiliation(s)
- Encarna Alejandre-Durán
- Departamento de Genética, Facultad de Ciencias, Edificio Gregor Mendel, Campus Rabanales, Universidad de Córdoba, 14071 Córdoba, Spain
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27
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Simões T, Teixeira MC, Fernandes AR, Sá-Correia I. Adaptation of Saccharomyces cerevisiae to the herbicide 2,4-dichlorophenoxyacetic acid, mediated by Msn2p- and Msn4p-regulated genes: important role of SPI1. Appl Environ Microbiol 2003; 69:4019-28. [PMID: 12839777 PMCID: PMC165130 DOI: 10.1128/aem.69.7.4019-4028.2003] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The possible roles of 13 Msn2p- and Msn4p-regulated genes in the adaptation of Saccharomyces cerevisiae to the herbicide 2,4-D-dichlorophenoxyacetic acid (2,4-D) were examined. Single deletion of genes involved in defense against oxidizing agents (CTT1, GRX1, and GRX2/TTR1) or encoding chaperones of the HSP70 family (SSA1, SSA4, and SSE2) showed a slight effect. A more significant role was observed for the heat shock genes HSP78, HSP26, HSP104, HSP12, and HSP42, most of which encode molecular chaperones. However, the SPI1 gene, encoding a member of the glycosylphosphatidylinositol-anchored cell wall protein family, emerged as the major determinant of 2,4-D resistance. SPI1 expression reduced the loss of viability of an unadapted yeast population suddenly exposed to the herbicide, allowing earlier growth resumption. Significantly, yeast adaptation to 2,4-D involves the rapid and transient Msn2p- and Msn4p-mediated activation (fivefold) of SPI1 transcription. SPI1 mRNA levels were reduced to values slightly above those in unstressed cells when the adapted population started duplication in the presence of 2,4-D. Since SPI1 deletion leads to the higher beta-1,3-glucanase sensitivity of 2,4-D-stressed cells, it was hypothesized that adaptation may involve an Spi1p-mediated increase in the diffusional restriction of the liposoluble acid form of the herbicide across the cell envelope. Such a cell response would avoid a futile cycle due to acid reentry into the cell counteracting the active export of the anionic form, presumably through an inducible plasma membrane transporter(s). Consistent with this concept, the concentration of (14)C-labeled 2,4-D in 2,4-D-energized adapted Deltaspi1 mutant cells and the consequent intracellular acidification are higher than in wild-type cells.
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Affiliation(s)
- T Simões
- Centro de Engenharia Biológica e Química, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
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28
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Török Z, Tsvetkova NM, Balogh G, Horváth I, Nagy E, Pénzes Z, Hargitai J, Bensaude O, Csermely P, Crowe JH, Maresca B, Vigh L. Heat shock protein coinducers with no effect on protein denaturation specifically modulate the membrane lipid phase. Proc Natl Acad Sci U S A 2003; 100:3131-6. [PMID: 12615993 PMCID: PMC152258 DOI: 10.1073/pnas.0438003100] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The hydroxylamine derivative bimoclomol (BM) has been shown to activate natural cytoprotective homeostatic responses by enhancing the capability of cells to cope with various pathophysiological conditions. It exerts its effect in synergy with low levels of stress to induce the synthesis of members of major stress protein families. We show here that the presence of BM does not influence protein denaturation in the cells. BM and its derivatives selectively interact with acidic lipids and modulate their thermal and dynamic properties. BM acts as a membrane fluidizer at normal temperature, but it is a highly efficient membrane stabilizer, inhibiting the bilayer-nonbilayer phase transitions during severe heat shock. We suggest that BM and the related compounds modify those domains of membrane lipids where the thermally or chemically induced perturbation of lipid phase is sensed and transduced into a cellular signal, leading to enhanced activation of heat shock genes. BM may be a prototype for clinically safe membrane-interacting drug candidates that rebalance the level and composition of heat shock proteins.
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Affiliation(s)
- Zsolt Török
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged, Hungary
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29
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Fernandes AR, Sá-Correia I. Transcription patterns of PMA1 and PMA2 genes and activity of plasma membrane H+-ATPase in Saccharomyces cerevisiae during diauxic growth and stationary phase. Yeast 2003; 20:207-19. [PMID: 12557274 DOI: 10.1002/yea.957] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
PMA1 and PMA2 genes encode Saccharomyces cerevisiae plasma membrane H(+)-ATPase (PM-H(+)-ATPase), an enzyme with critical physiological roles both in the absence or presence of environmental stress. The two PM-H(+)-ATPase isoforms differ in their biochemical characteristics but, under all the growth conditions that were examined so far, PMA2 expression is negligible and Pma1p accounts for practically the totality of cell PM-H(+)-ATPase activity. In the present work, we have compared gene expression levels and activity of this proton pump in yeast cells cultivated under fermentative or respiratory growth and under carbon starvation. The expression levels of both PMA1 and PMA2 genes were consistently higher (2.5-4.5-fold) in cells cultivated under respiratory metabolism (in ethanol-based medium or after the diauxic shift), than in cells cultivated under fermentative metabolism (during the full period of growth in a medium where glucose is not the limiting nutrient or during the first period of diauxic growth in low-glucose-based medium). The moderate upregulation of PMA1 and PMA2 transcription in cells grown on ethanol compared with those grown on glucose was reflected in the increased content and activity of PM-H(+)-ATPase. In diauxic growth, during transition to stationary phase after ethanol depletion, a further strong activation (eight-fold) of PMA2 gene transcription was observed. Although PMA2 transcription still remains quite below (20-fold) PMA1 transcription, this is the first environmental condition, identified so far, that leads to a significant PMA2 expression, suggesting that this PM-H(+)-ATPase isoform may play some role during carbon starvation.
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Affiliation(s)
- Alexandra R Fernandes
- Centro de Engenharia Biológica e Química, Instituto Superior Técnico, 1049-001 Lisboa, Portugal
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30
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Pillai B, Verma J, Abraham A, Francis P, Kumar Y, Tatu U, Brahmachari SK, Sadhale PP. Whole genome expression profiles of yeast RNA polymerase II core subunit, Rpb4, in stress and nonstress conditions. J Biol Chem 2003; 278:3339-46. [PMID: 12429747 DOI: 10.1074/jbc.m112180200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Organisms respond to environmental stress by adopting changes in gene expression at the transcriptional level. Rpb4, a nonessential subunit of the core RNA polymerase II has been proposed to play a role in non-stress-specific transcription and in the regulation of stress response in yeast. We find that in addition to the temperature sensitivity of the null mutant of Rpb4, diploid null mutants are also compromised in sporulation and show morphological changes associated with nitrogen starvation. Using whole genome expression analysis, we report here the effects of Rpb4 on expression of genes during normal growth and following heat shock and nutritional starvation. Our analysis shows that Rpb4 affects expression of a small yet significant fraction of the genome in both stress and normal conditions. We found that genes involved in galactose metabolism were dependent on the presence of Rpb4 irrespective of the environmental condition. Rpb4 was also found to affect the expression of several other genes specifically in conditions of nutritional starvation. The general defect in the absence of Rpb4 is in the expression of metabolic genes, especially those involved in carbon metabolism and energy generation. We report that various stresses are affected by RPB4 and that on overexpression the stress-specific activators can partially rescue the corresponding defects.
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Affiliation(s)
- Beena Pillai
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, 560 012, India
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31
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Madrid MP, Di Pietro A, Roncero MIG. Class V chitin synthase determines pathogenesis in the vascular wilt fungus Fusarium oxysporum and mediates resistance to plant defence compounds. Mol Microbiol 2003; 47:257-66. [PMID: 12492869 DOI: 10.1046/j.1365-2958.2003.03299.x] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Chitin, a beta-1,4-linked polysaccharide of N-acetylglucosamine, is a major structural component of fungal cell walls. Fungi have multiple classes of chitin synthases that catalyse N-acetylglucosamine polymerization. Here, we demonstrate the requirement for a class V chitin synthase during host infection by the vascular wilt pathogen Fusarium oxysporum. The chsV gene was identified in an insertional mutagenesis screen for pathogenicity mutants. ChsV has a putative myosin motor and a chitin synthase domain characteristic of class V chitin synthases. The chsV insertional mutant and a gene replacement mutant of F. oxysporum display morphological abnormalities such as hyphal swellings that are indicative of alterations in cell wall structure and can be partially restored by osmotic stabilizer. The mutants are unable to infect and colonize tomato plants or to grow invasively on tomato fruit tissue. They are also hypersensitive to plant antimicrobial defence compounds such as the tomato phytoanticipin alpha-tomatine or H2O2. Reintroduction of a functional chsV copy into the mutant restored the growth phenotype of the wild-type strain. These data suggest that F. oxysporum requires a specific class V chitin synthase for pathogenesis, most probably to protect itself against plant defence mechanisms.
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Affiliation(s)
- Martan P Madrid
- Departamento de Genética, Universidad de Córdoba, Campus Rabanales C5, 14071 Córdoba, Spain
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32
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Friedman M. Tomato glycoalkaloids: role in the plant and in the diet. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2002; 50:5751-80. [PMID: 12358437 DOI: 10.1021/jf020560c] [Citation(s) in RCA: 276] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Tomatoes, a major food source for humans, accumulate a variety of secondary metabolites including phenolic compounds, phytoalexins, protease inhibitors, and glycoalkaloids. These metabolites protect against adverse effects of hosts of predators including fungi, bacteria, viruses, and insects. Because glycoalkaloids are reported to be involved in host-plant resistance, on the one hand, and to have a variety of pharmacological and nutritional properties in animals and humans, on the other, a need exists to develop a better understanding of the role of these compounds both in the plant and in the diet. To contribute to this effort, this integrated review presents data on the history, composition, and nutrition of tomatoes, with special focus on the assessment of the chemistry, analysis, composition, nutrition, microbiology, and pharmacology of the tomato glycoalkaloids comprising alpha-tomatine and dehydrotomatine; their content in different parts of the tomato plant, in processed tomato products, and in wild and transgenic tomatoes; their biosynthesis, inheritance, metabolism, and catabolism; plant-microbe relationships with fungi, bacteria, viruses, insects, and worms; interactions with ergosterol and cholesterol; disruption of cell membranes; tomatine-induced tomatinases, pantothenate synthetase, steroid hydroxylases, and cytokines; and inhibition of acetylcholinesterase. Also covered are tomato-human pathogen relationships and tomatine-induced lowering of plasma cholesterol and triglycerides and enhancement of the immune system. Further research needs in each of these areas are suggested. The overlapping aspects are discussed in terms of general concepts for a better understanding of the impact of tomato glycoalkaloids in the plant in general and in food in particular. Such an understanding can lead to the creation of improved tomatoes and to improved practices on the farm and in the consumption of tomatoes.
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Affiliation(s)
- Mendel Friedman
- Western Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 800 Buchanan Street, Albany, California 94710, USA.
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33
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Burchett SA, Flanary P, Aston C, Jiang L, Young KH, Uetz P, Fields S, Dohlman HG. Regulation of stress response signaling by the N-terminal dishevelled/EGL-10/pleckstrin domain of Sst2, a regulator of G protein signaling in Saccharomyces cerevisiae. J Biol Chem 2002; 277:22156-67. [PMID: 11940600 DOI: 10.1074/jbc.m202254200] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
All members of the regulator of G protein signaling (RGS) family contain a conserved core domain that can accelerate G protein GTPase activity. The RGS in yeast, Sst2, can inhibit a G protein signal leading to mating. In addition, some RGS proteins contain an N-terminal domain of unknown function. Here we use complementary whole genome analysis methods to investigate the function of the N-terminal Sst2 domain. To identify a signaling pathway regulated by N-Sst2, we performed genome-wide transcription profiling of cells expressing this fragment alone and found differences in 53 transcripts. Of these, 40 are induced by N-Sst2, and nearly all contain a stress response element (STRE) in the promoter region. To identify components of a signaling pathway leading from N-Sst2 to STREs, we performed a genome-wide two-hybrid analysis using N-Sst2 as bait and found 17 interacting proteins. To identify the functionally relevant interacting proteins, we analyzed all of the available gene deletion mutants and found three (vps36 Delta, pep12 Delta, and tlg2 Delta) that induce STRE and also repress pheromone-dependent transcription. We selected VPS36 for further characterization. A vps36 Delta mutation diminishes signaling by pheromone as well as by downstream components including the G protein, effector kinase (Ste11), and transcription factor (Ste12). Conversely, overexpression of Vps36 enhances the pheromone response in sst2 Delta cells but not in wild type. These findings indicate that Vps36 and Sst2 have opposite and opposing effects on the pheromone and stress response pathways, with Vps36 acting downstream of the G protein and independently of Sst2 RGS activity.
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Affiliation(s)
- Scott A Burchett
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06536, USA
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34
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Abstract
The ability to adapt to altered availability of free water is a fundamental property of living cells. The principles underlying osmoadaptation are well conserved. The yeast Saccharomyces cerevisiae is an excellent model system with which to study the molecular biology and physiology of osmoadaptation. Upon a shift to high osmolarity, yeast cells rapidly stimulate a mitogen-activated protein (MAP) kinase cascade, the high-osmolarity glycerol (HOG) pathway, which orchestrates part of the transcriptional response. The dynamic operation of the HOG pathway has been well studied, and similar osmosensing pathways exist in other eukaryotes. Protein kinase A, which seems to mediate a response to diverse stress conditions, is also involved in the transcriptional response program. Expression changes after a shift to high osmolarity aim at adjusting metabolism and the production of cellular protectants. Accumulation of the osmolyte glycerol, which is also controlled by altering transmembrane glycerol transport, is of central importance. Upon a shift from high to low osmolarity, yeast cells stimulate a different MAP kinase cascade, the cell integrity pathway. The transcriptional program upon hypo-osmotic shock seems to aim at adjusting cell surface properties. Rapid export of glycerol is an important event in adaptation to low osmolarity. Osmoadaptation, adjustment of cell surface properties, and the control of cell morphogenesis, growth, and proliferation are highly coordinated processes. The Skn7p response regulator may be involved in coordinating these events. An integrated understanding of osmoadaptation requires not only knowledge of the function of many uncharacterized genes but also further insight into the time line of events, their interdependence, their dynamics, and their spatial organization as well as the importance of subtle effects.
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Affiliation(s)
- Stefan Hohmann
- Department of Cell and Molecular Biology/Microbiology, Göteborg University, S-405 30 Göteborg, Sweden.
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Kohli A, Mukhopadhyay K, Rattan A, Prasad R. In vitro low-level resistance to azoles in Candida albicans is associated with changes in membrane lipid fluidity and asymmetry. Antimicrob Agents Chemother 2002; 46:1046-52. [PMID: 11897588 PMCID: PMC127087 DOI: 10.1128/aac.46.4.1046-1052.2002] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The present study tracks the development of low-level azole resistance in in vitro fluconazole-adapted strains of Candida albicans, which were obtained by serially passaging a fluconazole-susceptible dose-dependent strain, YO1-16 (fluconazole MIC, 16 microg ml(-1)) in increasing concentrations of fluconazole, resulting in strains YO1-32 (fluconazole MIC, 32 microg ml(-1)) and YO1-64 (MIC, 64 microg ml(-1)). We show that acquired resistance to fluconazole in this series of isolates is not a random process but is a gradually evolved complex phenomenon that involves multiple changes, which included the overexpression of ABC transporter genes, e.g., CDR1 and CDR2, and the azole target enzyme, ERG11. The sequential rise in fluconazole MICs in these isolates was also accompanied by cross-resistance to other azoles and terbinafine. Interestingly, fluorescent polarization measurements performed by using the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene revealed that there was a gradual increase in membrane fluidity of adapted strains. The increase in fluidity was reflected by observed change in membrane order, which was considerably decreased (decrease in fluorescence polarization values, P value) in the adapted strain (P value of 0.1 in YO1-64, compared to 0.19 in the YO1-16 strain). The phospholipid composition of the adapted strain was not significantly altered; however, ergosterol content was reduced in YO1-64 from that in the YO1-16 strain. The asymmetrical distribution of phosphatidylethanolamine (PE) between two monolayers of plasma membrane was also changed, with PE becoming more exposed to the outer monolayer in the YO1-64 strain. The results of the present study suggest for the first time that changes in the status of membrane lipid phase and asymmetry could contribute to azole resistance in C. albicans.
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Affiliation(s)
- Avmeet Kohli
- Membrane Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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36
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Krishnamurthy S, Dixit BL, Gupta CM, Milewski S, Prasad R. ABC transporters Cdr1p, Cdr2p and Cdr3p of a human pathogen Candida albicans are general phospholipid translocators. Yeast 2002; 19:303-18. [PMID: 11870854 DOI: 10.1002/yea.818] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
We have used fluorescent 7-nitrobenz-2-oxa-1,3-diazol-4-yl (NBD)-tagged phospholipid analogues, NBD-PE (phosphatidylethanolamine), NBD-PC (phosphatidylcholine) and NBD-PS (phosphatidylserine), to demonstrate that Cdr1p and its other homologues, Cdr2p and Cdr3p, belonging to the ATP-binding cassette (ABC) superfamily behave as general phospholipid translocators. Interestingly, CDR1 and CDR2, whose overexpression leads to azole resistance in C. albicans, elicit in-to-out transbilayer phospholipid movement, while CDR3, which is not involved in drug resistance, carries out-to-in translocation of phospholipids between the two monolayers of plasma membrane. Cdr1p, Cdr2p and Cdr3p could be further distinguished on the basis of their sensitivities to different inhibitors. For example, the in-to-out activity associated with Cdr1p and Cdr2p is energy-dependent and sensitive to sulphydryl blocking agents such as N-ethylmaleimide (NEM) and cytoskeleton disrupting agent cytochalasin E, while Cdr3p-associated out-to-in activity is energy-dependent but insensitive to NEM and cytochalasin E. We found that certain drugs, such as fluconazole, cycloheximide and miconazole, to which Cdr1p confers resistance could also affect in-to-out transbilayer movement of NBD-PE, while the same drugs had no effect on Cdr3p-mediated out-to-in translocation of NBD-PE. The ineffectiveness of these drugs to affect Cdr3p mediated out-to-in phospholipid translocation further confirms the inherent difference in the directionality of phospholipid translocation between these pumps. Notwithstanding the role of some of the Cdrps in drug resistance, this study clearly demonstrates that these ABC transporters of C. albicans are phospholipid translocators and this function could represent one of the physiological functions of such large family of proteins.
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Dual Role of Membranes in Heat Stress: As Thermosensors They Modulate the Expression of Stress Genes and, by Interacting with Stress Proteins, Re-organize Their Own Lipid Order and Functionality. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s1568-1254(02)80014-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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38
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Fernandes AR, Sá-Correia I. The activity of plasma membrane H(+)-ATPase is strongly stimulated during Saccharomyces cerevisiae adaptation to growth under high copper stress, accompanying intracellular acidification. Yeast 2001; 18:511-21. [PMID: 11284007 DOI: 10.1002/yea.702] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
For the adaptation of cells of Saccharomyces cerevisiae, a period of latency is necessary before exponential growth is resumed in a medium supplemented with a highly inhibitory concentration of copper. In this work, we have examined some physiological responses occurring during this period of adaptation. The results revealed that plasma membrane H(+)-ATPase (PM-ATPase) activity is strongly stimulated (up to 24-fold) during copper-induced latency in growth medium with glucose, reaching maximal levels when the cells were about to start inhibited exponential growth. This in vivo activation of the ATPase activity by copper was accompanied by the stimulation of the H(+)-pumping activity of the enzyme in vivo and was essentially due to the increase of the apparent V(max) for MgATP. Although the exact molecular basis of the reported plasma membrane ATPase activation was not clarified, no increase in the mRNA levels from the encoding genes PMA1 and PMA2 was apparently detected during copper-induced latency. The physiological response reported here may allow the cells to cope with copper-induced lipid peroxidation and consequent decrease in plasma membrane lipid ordering and increase in the non-specific permeability to protons. The consequences of these copper deleterious effects were revealed by the decrease of the intracellular pH (pH(i)) of the yeast population, from approximately pH(i) 6 to pH(i) 5, during copper-induced latency in growth medium at pH 4.3. The time-dependent patterns of plasma membrane ATPase activation and of the decrease of pH(i) during the period of adaptation to growth with copper correlate, suggesting that the regulation of this membrane enzyme activity may be triggered by intracellular acidification. Consistent with this idea, when exponential growth under copper stress was resumed and the pH(i) of the yeast population recovered up to physiological values, plasma membrane ATPase activity simultaneously decreased from the highly stimulated level attained during the adaptation period of latency.
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Affiliation(s)
- A R Fernandes
- Centro de Engenharia Biológica e Química, Instituto Superior Técnico, 1049-001 Lisboa, Portugal
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Goossens A, de La Fuente N, Forment J, Serrano R, Portillo F. Regulation of yeast H(+)-ATPase by protein kinases belonging to a family dedicated to activation of plasma membrane transporters. Mol Cell Biol 2000; 20:7654-61. [PMID: 11003661 PMCID: PMC86331 DOI: 10.1128/mcb.20.20.7654-7661.2000] [Citation(s) in RCA: 150] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The regulation of electrical membrane potential is a fundamental property of living cells. This biophysical parameter determines nutrient uptake, intracellular potassium and turgor, uptake of toxic cations, and stress responses. In fungi and plants, an important determinant of membrane potential is the electrogenic proton-pumping ATPase, but the systems that modulate its activity remain largely unknown. We have characterized two genes from Saccharomyces cerevisiae, PTK2 and HRK1 (YOR267c), that encode protein kinases implicated in activation of the yeast plasma membrane H(+)-ATPase (Pma1) in response to glucose metabolism. These kinases mediate, directly or indirectly, an increase in affinity of Pma1 for ATP, which probably involves Ser-899 phosphorylation. Ptk2 has the strongest effect on Pma1, and ptk2 mutants exhibit a pleiotropic phenotype of tolerance to toxic cations, including sodium, lithium, manganese, tetramethylammonium, hygromycin B, and norspermidine. A plausible interpretation is that ptk2 mutants have a decreased membrane potential and that diverse cation transporters are voltage dependent. Accordingly, ptk2 mutants exhibited reduced uptake of lithium and methylammonium. Ptk2 and Hrk1 belong to a subgroup of yeast protein kinases dedicated to the regulation of plasma membrane transporters, which include Npr1 (regulator of Gap1 and Tat2 amino acid transporters) and Hal4 and Hal5 (regulators of Trk1 and Trk2 potassium transporters).
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Affiliation(s)
- A Goossens
- Instituto de Biologia Molecular y Celular de Plantas, Universidad Politecnica de Valencia-C.S.I.C., 46022 Valencia, Spain
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40
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Estruch F. Stress-controlled transcription factors, stress-induced genes and stress tolerance in budding yeast. FEMS Microbiol Rev 2000; 24:469-86. [PMID: 10978547 DOI: 10.1111/j.1574-6976.2000.tb00551.x] [Citation(s) in RCA: 402] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The transcriptional response to environmental changes is a major topic in both basic and applied research. From a basic point of view, to understand this response includes unravelling how the stress signal is sensed and transduced to the nucleus, to identify which genes are induced under each stress condition and, finally, to establish the phenotypic consequences of this induction in stress tolerance. The possibility of using genetic approaches has made the yeast Saccharomyces cerevisiae a compelling model to study stress response at a molecular level. Moreover, this information can be used to isolate and characterise stress-related proteins in higher eukaryotes and to design strategies to increase stress resistance in organisms of industrial interest. In this review the progress made in recent years is discussed.
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Affiliation(s)
- F Estruch
- Departamento de Bioquímica y Biología Molecular, Universitat de Valencia, Burjassot, Spain.
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41
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Garreau H, Hasan RN, Renault G, Estruch F, Boy-Marcotte E, Jacquet M. Hyperphosphorylation of Msn2p and Msn4p in response to heat shock and the diauxic shift is inhibited by cAMP in Saccharomyces cerevisiae. MICROBIOLOGY (READING, ENGLAND) 2000; 146 ( Pt 9):2113-2120. [PMID: 10974099 DOI: 10.1099/00221287-146-9-2113] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In response to various stresses, as well as during the diauxic transition, the Msn2p and Msn4p transcription factors of Saccharomyces cerevisiae are activated and induce a large set of genes. This activation is inhibited by the Ras/cAMP/PKA (cAMP-dependent protein kinase) pathway. Here we show by immunoblotting experiments that Msn2p and Msn4p are phosphorylated in vivo during growth on glucose, and become hyperphosphorylated at the diauxic transition and upon heat shock. This hyperphosphorylation is correlated with activation of Msn2/4p-dependent transcription. An increased level of cAMP prevents and reverses these hyperphosphorylations, indicating that kinases other than PKA are involved. These results suggest that PKA and stress-activated kinases control Msn2/4p activity by antagonistic phosphorylation. It was also noted that Msn4p is transiently increased at the diauxic transition. Msn2p and Msn4p present different hyperphosphorylation patterns in response to different stresses.
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Affiliation(s)
- Hervé Garreau
- Laboratoire Information Génétique et Développement, Institut de Génétique et Microbiologie, UMR CNRS C8621, Université Paris-Sud, Bâtiment 400, 91405 Orsay cedex, France1
| | - Rukhsana Nilofer Hasan
- Laboratoire Information Génétique et Développement, Institut de Génétique et Microbiologie, UMR CNRS C8621, Université Paris-Sud, Bâtiment 400, 91405 Orsay cedex, France1
| | - Georges Renault
- Laboratoire Information Génétique et Développement, Institut de Génétique et Microbiologie, UMR CNRS C8621, Université Paris-Sud, Bâtiment 400, 91405 Orsay cedex, France1
| | - Francisco Estruch
- Dpto. Bioquı́mica y Biol. Molecular, Universitat de Valencia, and Dpto. Biotecnologia IATA, CSIC, Apdo Correos 73.46100 Burjassot, Valencia, Spain2
| | - Emmanuelle Boy-Marcotte
- Laboratoire Information Génétique et Développement, Institut de Génétique et Microbiologie, UMR CNRS C8621, Université Paris-Sud, Bâtiment 400, 91405 Orsay cedex, France1
| | - Michel Jacquet
- Laboratoire Information Génétique et Développement, Institut de Génétique et Microbiologie, UMR CNRS C8621, Université Paris-Sud, Bâtiment 400, 91405 Orsay cedex, France1
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42
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Rep M, Krantz M, Thevelein JM, Hohmann S. The transcriptional response of Saccharomyces cerevisiae to osmotic shock. Hot1p and Msn2p/Msn4p are required for the induction of subsets of high osmolarity glycerol pathway-dependent genes. J Biol Chem 2000; 275:8290-300. [PMID: 10722658 DOI: 10.1074/jbc.275.12.8290] [Citation(s) in RCA: 445] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have analyzed the transcriptional response to osmotic shock in the yeast Saccharomyces cerevisiae. The mRNA level of 186 genes increased at least 3-fold after a shift to NaCl or sorbitol, whereas that of more than 100 genes was at least 1.5-fold diminished. Many induced genes encode proteins that presumably contribute to protection against different types of damage or encode enzymes in glycerol, trehalose, and glycogen metabolism. Several genes, which encode poorly expressed isoforms of enzymes in carbohydrate metabolism, were induced. The high osmolarity glycerol (HOG) pathway is required for full induction of many but not all genes. The recently characterized Hot1p transcription factor is required for normal expression of a subset of the HOG pathway-dependent responses. Stimulated expression of the genes that required the general stress-response transcription factors Msn2p and Msn4p was also reduced in a hog1 mutant, suggesting that Msn2p/Msn4p might be regulated by the HOG pathway. The expression of genes that are known to be controlled by the mating pheromone response pathway was stimulated by osmotic shock specifically in a hog1 mutant. Inappropriate activation of the mating response may contribute to the growth defect of a hog1 mutant in high osmolarity medium.
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Affiliation(s)
- M Rep
- Laboratorium voor Moleculaire Celbiologie, Katholieke Universiteit Leuven, Kardinaal Mercierlaan 92, B-3001 Leuven-Heverlee, Flanders, Belgium
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Kamińska J, Tobiasz A, Gniewosz M, Zoładek T. The growth of mdp1/rsp5 mutants of Saccharomyces cerevisiae is affected by mutations in the ATP-binding domain of the plasma membrane H+ -ATPase. Gene 2000; 242:133-40. [PMID: 10721705 DOI: 10.1016/s0378-1119(99)00535-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Mutations in the PMA1 gene, encoding plasma membrane H+ -ATPase, were isolated that are able to suppress the temperature sensitivity (ts) phenotype of mdp1 mutations located in RSP5, the ubiquitin-protein ligase gene. The mdp1 mutants were previously found to change the mitochondrial/cytosolic distribution of Mod5p-I, the tRNA modifying enzyme, and to affect fluid phase endocytosis. The data presented reveal that mdp1 mutants are also pH sensitive, and hypersensitive to hygromycin B and paromomycin. The ts phenotype, hygromycin B and paromomycin sensitivity are suppressed by pmal-t, but the pH sensitivity, the effect of mdp1 on Mod5p-I cytoplasmic/mitochondrial localization and endocytosis are not. Characterization of pmal-t revealed the substitution of amino acid G(653)V in the ATP-binding domain of the H+ -ATPase. Our results indicate that Rsp5 ubiquitin-protein ligase may also influence, in addition to protein distribution, the functioning of plasma membrane H+ -ATPase and the response of cells to stress.
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Affiliation(s)
- J Kamińska
- Department of Genetics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw
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