Project description:The Tup1-Cyc8 complex in Saccharomyces cerevisiae was one of the first global co-repressors of gene transcription discovered. The model for Tup1-Cyc8 function proposes that Tup1p mediates the repression activity, whilst Cyc8p recruits the complex to target genes. However, despite years of study, a full understanding of the contribution of Tup1p and Cyc8p to complex function is lacking. We examined TUP1 and CYC8 single and double deletion mutants and show that CYC8 represses more genes than TUP1, and there are genes subject to (i) unique repression by TUP1 or CYC8, (ii) redundant repression by TUP1 and CYC8, and (iii) there are genes at which de-repression in a cyc8 mutant is dependent upon TUP1, and vice-versa. We also reveal that Tup1p and Cyc8p can make distinct contributions to commonly repressed genes possibly via specific interactions with histone deacetylases. Furthermore, we show that Tup1p and Cyc8p can be found independently of each other to negatively regulate gene transcription and can persist at active genes to negatively regulate on-going transcription. Together, these data suggest that Tup1p and Cyc8p can associate with inactive and active genes to mediate distinct negative and positive regulatory roles when functioning within, and possibly out with the complex.
Project description:Saccharomyces cerevisiae normally cannot assimilate mannitol, a promising brown macroalgal carbon source for bioethanol production. To date, the molecular mechanisms underlying this inability remain unknown. Here, we found that cells acquiring mannitol-assimilating ability appeared from wild-type S. cerevisiae strain during prolonged culture in mannitol medium. Our microarray analysis revealed that genes for putative mannitol dehydrogenase and hexose transporters were up-regulated in cells acquiring mannitol-assimilating ability. Take account of our other results including complementation analysis and cell growth data, we demonstrated that this acquisition of mannitol-assimilating ability was due to the spontaneous mutation in the gene encoding Tup1 or Cyc8. Tup1-Cyc8 is the general corepressor complex involved in the repression of many kinds of genes. Thus, it is suggested that the inability of wild-type S. cerevisiae to assimilate mannitol can be attributed to the transcriptional repression of a set of genes involved in mannitol utilization by Tup1-Cyc8 corepressor. In other words, Tup1-Cyc8 is a key regulator of mannitol metabolism in S. cerevisiae. We also showed that S. cerevisiae strain which carries mutant allele of TUP1 or CYC8 produced ethanol from mannitol efficiently. Especially, strain carrying mutant allele of CYC8 showed high tolerance to salt, which is superior to other ethanologenic microorganisms. This characteristic is highly beneficial to produce bioethanol from marine biomass. Taken together, Tup1-Cyc8 can be an ideal target to develop a yeast-algal bioethanol production system. To figure out how Mtl+ strains (cells acquiring ability to grow in mannitol medium) had acquired the ability to assimilate mannitol, we performed genome-wide analysis by using Nimblegen microarrays. Yeast Saccharomyces cerevisiae cells (wild-type BY4742 strain and two Mtl+ strains, MK3619 and MK3683) were grown at 30°C to the logarithmic phase in SC or SM media. Total RNA was purified and the 4 RNA samples (BY4742 cells in SC as control, MK3619 cells in SM, MK3683 cells in both SC and SM) were analyzed with Nimblegen microarrays.
Project description:Saccharomyces cerevisiae normally cannot assimilate mannitol, a promising brown macroalgal carbon source for bioethanol production. To date, the molecular mechanisms underlying this inability remain unknown. Here, we found that cells acquiring mannitol-assimilating ability appeared from wild-type S. cerevisiae strain during prolonged culture in mannitol medium. Our microarray analysis revealed that genes for putative mannitol dehydrogenase and hexose transporters were up-regulated in cells acquiring mannitol-assimilating ability. Take account of our other results including complementation analysis and cell growth data, we demonstrated that this acquisition of mannitol-assimilating ability was due to the spontaneous mutation in the gene encoding Tup1 or Cyc8. Tup1-Cyc8 is the general corepressor complex involved in the repression of many kinds of genes. Thus, it is suggested that the inability of wild-type S. cerevisiae to assimilate mannitol can be attributed to the transcriptional repression of a set of genes involved in mannitol utilization by Tup1-Cyc8 corepressor. In other words, Tup1-Cyc8 is a key regulator of mannitol metabolism in S. cerevisiae. We also showed that S. cerevisiae strain which carries mutant allele of TUP1 or CYC8 produced ethanol from mannitol efficiently. Especially, strain carrying mutant allele of CYC8 showed high tolerance to salt, which is superior to other ethanologenic microorganisms. This characteristic is highly beneficial to produce bioethanol from marine biomass. Taken together, Tup1-Cyc8 can be an ideal target to develop a yeast-algal bioethanol production system. To figure out how Mtl+ strains (cells acquiring ability to grow in mannitol medium) had acquired the ability to assimilate mannitol, we performed genome-wide analysis by using Nimblegen microarrays.
Project description:The transcriptome from a S. cerevisiae tup1 deletion mutant was one of the first comprehensive yeast transcriptomes published. Subsequent transcriptomes from tup1 and cyc8 mutants firmly established the Tup1-Cyc8 complex as predominantly acting as a repressor of gene transcription. However, transcriptomes from tup1/cyc8 gene deletion or conditional mutants would all have been influenced by the striking flocculation phenotypes that these mutants display. In this study, we have separated the impact of flocculation from the transcriptome in a cyc8 conditional mutant to reveal those genes (i) subject solely to Cyc8p dependent regulation, (ii) regulated by flocculation only, and (iii) regulated by Cyc8p and further influenced by flocculation. We reveal an improved Cyc8p transcriptome that includes newly identified Cyc8p-regulated genes that were masked by the flocculation phenotype and excludes genes which were indirectly influenced by flocculation and not regulated by Cyc8p. Furthermore, we show evidence to suggest that flocculation exerts a complex and potentially dynamic influence upon global gene transcription. These data should be of interest to future studies into the mechanism of action of the Tup1-Cyc8 complex and to those involved in understanding the development of flocculation and its impact upon cell function.
Project description:This SuperSeries is composed of the following subset Series: GSE37465: Global Regulation of Nucleosome Organization And Transcription By The Yeast Ssn6-Tup1 Corepressor (MNase-Seq) GSE37466: Global Regulation of Nucleosome Organization And Transcription By The Yeast Ssn6-Tup1 Corepressor (expression) Refer to individual Series
Project description:The yeast Ssn6-Tup1 complex regulates gene expression through a variety of mechanisms, including positioning of nucleosomes over promoters of some target genes to limit accessibility to the transcription machinery. To further define the functions of Ssn6-Tup1 in gene regulation and chromatin remodeling, we performed genome-wide profiling of changes in nucleosome organization and gene expression that occur upon loss of SSN6 or TUP1, and observed extensive nucleosome alterations in both promoters and gene bodies of derepressed genes. Our improved nucleosome profiling and analysis approaches revealed low-occupancy promoter nucleosomes (P nucleosomes) at locations previously defined as nucleosome-free regions. In the absence of SSN6 or TUP1, this P nucleosome is frequently lost, whereas nucleosomes are gained at -1 and +1 positions, accompanying up-regulation of downstream genes. Our analysis of public ChIP-seq data revealed that Ssn6 and Tup1 preferentially bind TATA-containing promoters, which are also enriched in genes derepressed upon loss of SSN6 or TUP1. These results suggest that stabilization of the P nucleosome on TATA-containing promoters may be a central feature of the repressive chromatin architecture created by the Ssn6-Tup1 corepressor, and that releasing the P nucleosome contributes to gene activation.
Project description:The yeast Ssn6-Tup1 complex regulates gene expression through a variety of mechanisms, including positioning of nucleosomes over promoters of some target genes to limit accessibility to the transcription machinery. To further define the functions of Ssn6-Tup1 in gene regulation and chromatin remodeling, we performed genome-wide profiling of changes in nucleosome organization and gene expression that occur upon loss of SSN6 or TUP1, and observed extensive nucleosome alterations in both promoters and gene bodies of derepressed genes. Our improved nucleosome profiling and analysis approaches revealed low-occupancy promoter nucleosomes (P nucleosomes) at locations previously defined as nucleosome-free regions. In the absence of SSN6 or TUP1, this P nucleosome is frequently lost, whereas nucleosomes are gained at -1 and +1 positions, accompanying up-regulation of downstream genes. Our analysis of public ChIP-seq data revealed that Ssn6 and Tup1 preferentially bind TATA-containing promoters, which are also enriched in genes derepressed upon loss of SSN6 or TUP1. These results suggest that stabilization of the P nucleosome on TATA-containing promoters may be a central feature of the repressive chromatin architecture created by the Ssn6-Tup1 corepressor, and that releasing the P nucleosome contributes to gene activation. Genome-wide expression profiling Yeast gene expression in three cell type, Each cell type is tested in duplicate.
Project description:The yeast Ssn6-Tup1 complex regulates gene expression through a variety of mechanisms, including positioning of nucleosomes over promoters of some target genes to limit accessibility to the transcription machinery. To further define the functions of Ssn6-Tup1 in gene regulation and chromatin remodeling, we performed genome-wide profiling of changes in nucleosome organization and gene expression that occur upon loss of SSN6 or TUP1, and observed extensive nucleosome alterations in both promoters and gene bodies of derepressed genes. Our improved nucleosome profiling and analysis approaches revealed low-occupancy promoter nucleosomes (P nucleosomes) at locations previously defined as nucleosome-free regions. In the absence of SSN6 or TUP1, this P nucleosome is frequently lost, whereas nucleosomes are gained at -1 and +1 positions, accompanying up-regulation of downstream genes. Our analysis of public ChIP-seq data revealed that Ssn6 and Tup1 preferentially bind TATA-containing promoters, which are also enriched in genes derepressed upon loss of SSN6 or TUP1. These results suggest that stabilization of the P nucleosome on TATA-containing promoters may be a central feature of the repressive chromatin architecture created by the Ssn6-Tup1 corepressor, and that releasing the P nucleosome contributes to gene activation.
Project description:Cells are often exposed to physical or chemical stresses that can damage the structures of essential biomolecules. Stress-induced cellular damage can become deleterious if not managed appropriately. Rapid and adaptive responses to stresses are therefore crucial for cell survival. In eukaryotic cells, different stresses trigger post-translational modification of proteins with the small ubiquitin-like modifier SUMO. However, the specific regulatory roles of sumoylation in each stress response are not well understood. Here, we examined the sumoylation events that occur in budding yeast after exposure to hyperosmotic stress. We discovered by proteomic and biochemical analyses that hyperosmotic stress incurs the rapid and transient sumoylation of Cyc8 and Tup1, which together form a conserved transcription corepressor complex that regulates hundreds of genes. Gene expression and cell biological analyses revealed that sumoylation of each protein directs distinct outcomes. In particular, we discovered that Cyc8 sumoylation prevents the persistence of hyperosmotic stress-induced Cyc8-Tup1 inclusions, which involves a glutamine-rich prion domain in Cyc8. We propose that sumoylation protects against persistent inclusion formation during hyperosmotic stress, allowing optimal transcriptional function of the Cyc8-Tup1 complex.
Project description:The yeast Ssn6-Tup1 complex regulates gene expression through a variety of mechanisms, including positioning of nucleosomes over promoters of some target genes to limit accessibility to the transcription machinery. To further define the functions of Ssn6-Tup1 in gene regulation and chromatin remodeling, we performed genome-wide profiling of changes in nucleosome organization and gene expression that occur upon loss of SSN6 or TUP1, and observed extensive nucleosome alterations in both promoters and gene bodies of derepressed genes. Our improved nucleosome profiling and analysis approaches revealed low-occupancy promoter nucleosomes (P nucleosomes) at locations previously defined as nucleosome-free regions. In the absence of SSN6 or TUP1, this P nucleosome is frequently lost, whereas nucleosomes are gained at -1 and +1 positions, accompanying up-regulation of downstream genes. Our analysis of public ChIP-seq data revealed that Ssn6 and Tup1 preferentially bind TATA-containing promoters, which are also enriched in genes derepressed upon loss of SSN6 or TUP1. These results suggest that stabilization of the P nucleosome on TATA-containing promoters may be a central feature of the repressive chromatin architecture created by the Ssn6-Tup1 corepressor, and that releasing the P nucleosome contributes to gene activation. nucleosomes were prepared from isogenic wild type (BY4742), ssn6 KO and tup1 KO cells after varying degrees of micrococcal nuclease (MNase) digestion, followed by isolation of mononucleosomal DNA and sequencing. Three replicates of each strain (9 samples) were subjected to Illumina sequencing.