Genome-wide mapping of the binding sites of transcription factor Cst6p in Saccharomyces cerevisiae
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ABSTRACT: The transcription factor Cst6p in Saccharomyces cerevisiae has been reported to play important roles in several biological processes. However, the genome-wide targets of Cst6p and the mechanisms for its physiological functions remain unknown. Here, we mapped the genome-wide binding sites of Cst6p with ChIP-exo at high resolution. Cst6p binds to the promoter regions of 59 genes with various biological functions when cells are grown on ethanol, but hardly binds to the genome on glucose. The growth deficiency of CST6 deletion mutant on ethanol is attributed to the markedly decreased expression of carbonic anhydrase gene NCE103, which is a direct target of Cst6p. The target genes of Cst6p have a large overlap with those of stress-responsive transcription factors, such as Sko1p and Skn7p. In addition, the CST6 deletion mutant growing on ethanol shows hypersensitivity to oxidative stress and ethanol stress, assigning Cst6p as a new member of the stress-responsive transcriptional regulatory network. These results show that genome-wide binding site mapping is able to provide new insights into the function of transcription factors, and highlight the highly connected and condition-dependent nature of the transcriptional regulatory network in S. cerevisiae.
Project description:The transcription factor Cst6p in Saccharomyces cerevisiae has been reported to play important roles in several biological processes. However, the genome-wide targets of Cst6p and the mechanisms for its physiological functions remain unknown. Here, we mapped the genome-wide binding sites of Cst6p with ChIP-exo at high resolution. Cst6p binds to the promoter regions of 59 genes with various biological functions when cells are grown on ethanol, but hardly binds to the genome on glucose. The growth deficiency of CST6 deletion mutant on ethanol is attributed to the markedly decreased expression of carbonic anhydrase gene NCE103, which is a direct target of Cst6p. The target genes of Cst6p have a large overlap with those of stress-responsive transcription factors, such as Sko1p and Skn7p. In addition, the CST6 deletion mutant growing on ethanol shows hypersensitivity to oxidative stress and ethanol stress, assigning Cst6p as a new member of the stress-responsive transcriptional regulatory network. These results show that genome-wide binding site mapping is able to provide new insights into the function of transcription factors, and highlight the highly connected and condition-dependent nature of the transcriptional regulatory network in S. cerevisiae. The binding sites of Cst6p when cells were grown in glucose or ethanol were measured in biological duplicates, so there are four samples in total.
Project description:Evolutionary engineering strategy was used for selection of ethanol-tolerant Saccharomyces cerevisiae clones under gradually increasing ethanol stress levels. Clones B2 and B8 were selected based on their higher ethanol-tolerance and higher ethanol production levels. Whole genome microarray analysis was used for identifying the gene expression levels of these two evolved clones compared to the reference strain.
Project description:ppGpp accumulation caused by ectopic expression of RelA in Saccharomyces cerevisiae gave rise to marked changes in gene expression with both upregulation and downregulation, including changes in mitochondrial gene expression. The most prominent upregulation (38-fold) was detected in the function-unknown hypothetical gene YBR072C-A, followed by many other known stress-responsive genes. ppGpp acuumulation resulted in enhancement of tolerance against various stress stimuli, such as osmotic stress, ethanol, hydrogen peroxide, and high temperature.
Project description:We used genome-wide expression analyses to study the response of Saccharomyces cerevisiae to stress throughout a 15-day wine fermentation. Forty percent of the yeast genome significantly changed expression levels to mediate long-term adaptation to an environment in which ethanol is both a stressor and a carbon source. Within this set, we identify a group of 223 genes, designated as the Fermentation Stress Response (FSR), that are dramatically and permanently induced; FSR genes exhibited changes ranging from four-to eighty-fold. The FSR is novel; 62% of the genes involved have not been implicated in global stress responses and 28% of the genes have no functional annotation. Genes involved in respiratory metabolism and gluconeogenesis were expressed during fermentation despite the presence of high concentrations of glucose. Ethanol, rather than nutrient depletion, was responsible for entry of yeast cells into stationary phase. Ethanol seems to regulate yeast metabolism through hitherto undiscovered regulatory networks during wine fermentation. Keywords: time course, stress response, fermentation
Project description:Physiological effects of carbon dioxide and impact on genome-wide transcript profiles were analysed in chemostat cultures of Saccharomyces cerevisiae. In anaerobic, glucose-limited chemostat cultures grown at atmospheric pressure, cultivation under CO2-saturated conditions had only a marginal (<10%) impact on the biomass yield. Conversely, a 25% decrease of the biomass yield was found in aerobic, glucose-limited chemostat cultures aerated with a mixture of 79% CO2 and 21% O2. This observation indicated that respiratory metabolism is more sensitive to CO2 than fermentative metabolism. Consistent with the more pronounced physiological effects of CO2 in respiratory cultures, the number of CO2-responsive transcripts was higher in aerobic cultures than in anaerobic cultures. Many genes involved in mitochondrial functions showed a transcriptional response to elevated CO2 concentrations. This is consistent with an uncoupling effect of CO2 and/or intracellular bicarbonate on the mitochondrial inner membrane. Other transcripts that showed a significant transcriptional response to elevated CO2 included NCE103 (probably encoding carbonic anhydrase), PCK1 (encoding PEP carboxykinase) and members of the IMD gene family (encoding isozymes of inosine monophosphate dehydrogenase Experiment Overall Design: Knowledge on the genome-wide transcriptional response of S. cerevisiae to high CO2 concentrations may provide a deeper insight into the molecular mechanisms of CO2 stress. Such insight is essential to develop metabolic-engineering strategies for improving CO2 tolerance. Furthermore, identification of âsignature transcriptsâ that uniquely respond to CO2 stress may be applicable for diagnosing the CO2 status of industrial fermentations. It has recently been demonstrated that the combination of chemostat cultivation with DNA-microarray-based transcriptome analysis offers a powerful and reproducible approach to identify the transcriptional responses of yeasts to environmental parameters For this reason, in the present study we used chemostat cultures of S. cerevisiae to quantify the effect of CO2 on respiring and fermenting cells, and to determine the genome-wide transcriptional responses of this yeast to high CO2 concentrations.
Project description:Ethanol is a valuable industrial product and a common metabolite used by many cell types. However, this molecule produces high levels of cytotoxicity affecting cellular performance at several levels. In the presence of ethanol, cells must adjust some of their components, such as the membrane lipids to maintain homeostasis. In the case of microorganism as Saccharomyces cerevisiae, ethanol is one of the principal products of their metabolism and is the main stress factor during fermentation. Although many efforts have been made, mechanisms of ethanol tolerance are not fully understood and very little evidence is available to date for specific signaling by ethanol in the cell. This work studied two Saccharomyces cerevisiae strains, CECT10094 and Temohaya-26, isolated from flor wine and traditional fermentations respectively, which differ in ethanol tolerance, in order to understand the molecular mechanisms underlying the ethanol stress response and the reasons for different ethanol tolerance. The transcriptome was analyzed after ethanol stress and, among others, an increased activation of genes related with the unfolded protein response (UPR) and its transcription factor, Hac1p, was observed in the tolerant strain CECT10094. We observed that this strain also resist more UPR agents than Temohaya-26 and the UPR-ethanol stress correlation was corroborated observing growth of 15 more strains and discarding UPR correlation with other stresses as thermal or oxidative stress. Furthermore, higher activation of UPR pathway in the tolerant strain CECT10094 was observed using a UPR mCherry reporter. Finally, we observed UPR activation in response to ethanol stress in other S. cerevisiae ethanol tolerant strains as the wine strains T73 and EC1118.
Project description:In our previous work, we had found that Saccharomyces cerevisiae needs of the Hog1 and Slt2 proteins to growth in a low pH environment caused by sulfuric acid, one of the stress factors during the process of ethanol production. Then was performed the gene-wide expression analysis in the hog1∆ and slt2∆ mutants in order to reveal the function of the Hog1p and Slt2p MAP Kinases in the regulation of S. cerevisiae global gene expression upon stress by sulfuric acid.
Project description:ppGpp accumulation caused by ectopic expression of RelA in Saccharomyces cerevisiae gave rise to marked changes in gene expression with both upregulation and downregulation, including changes in mitochondrial gene expression. The most prominent upregulation (38-fold) was detected in the function-unknown hypothetical gene YBR072C-A, followed by many other known stress-responsive genes. ppGpp acuumulation resulted in enhancement of tolerance against various stress stimuli, such as osmotic stress, ethanol, hydrogen peroxide, and high temperature. A two chip study using total RNA recoverd from the Saccharomyces cerevisiae TN2080 (accumulating ppGpp) and TN2077 (vector control) grown to mid-growth phase (8h) in SC-uracil medium. The plasmid pYC2/CT (V5-epitope tag vector) was used as a vector to express Sj-RSH.
Project description:Diploid and haploid strains often exhibit different tolerance to variety of stresses. Transcriptome of acclimation to ethanol stress in diploid and haploid strain of Saccharomyces cerevisiae was analyzed. We analyzed transcriptome profiles of diploid and haploid strains in the presence of ethanol.
Project description:Hybrid progeny can enjoy increased fitness and stress tolerance relative to their ancestral species, a phenomenon known as hybrid vigor. Though this phenomenon has been documented throughout the Eukarya, evolution of hybrid populations has yet to be explored experimentally in the lab. To fill this knowledge gap we created a pool of Saccharomyces cerevisiae and S. bayanus homoploid and aneuploid hybrids, and then investigated how selection in the form of incrementally increased temperature or ethanol impacted hybrid genome structure and adaptation. During 500 generations of continuous ammonia-limited, glucose-sufficient culture, temperature was raised from 25C to 46??C. This selection invariably resulted in nearly-complete loss of the S. bayanus genome, although the dynamics of genome loss differed among independent replicates. Temperature-evolved isolates were significantly more thermal tolerant and exhibited greater phenotypic plasticity than parental species and founding hybrids. By contrast, when the same hybrid pool was subjected to increases in exogenous ethanol from 0% to 14%, selection favored euploid S. cerevisiae x S. bayanus hybrids. Ethanol-evolved isolates exhibited significantly greater ethanol tolerance relative only to S. bayanus and one of the founding hybrids tested. Adaptation to thermal and ethanol stress manifested as heritable changes in cell wall structure demonstrated by resistance to zymolyase or micafungin treatment. This is the first study to show experimentally that the fate of interspecific hybrids critically depends on the type of selection they encounter during the course of evolution.