Project description:The Saccharomyces cerevisiae Swi-Snf co-activator complex was the first ATP-dependent chromatin remodelling complex discovered which functions by altering promoter chromatin structure to enable gene transcription. Conversely, the yeast Tup1-Cyc8 complex was identified as the first global co-repressor which can repress transcription by establishing ordered arrays of hypoacetylated nucleosomes across gene promoters. Although studies have indicated potential cooperation between these archetypal complexes upon transcription regulation, the precise mechanism and global extent of this antagonistic interplay remains unclear. We have identified all of the genes subject to repression by Tup1-Cyc8 and activation by Swi-Snf in glucose-grown yeast. These antagonistically regulated genes are enriched for those involved in cell wall structure and sugar metabolism. The data reveals that some co-regulated genes are kept inactive by Tup1-Cyc8 in wt and are de-repressed in the absence of CYC8 in a SNF2-dependent manner. Conversely, other co-regulated genes are actively transcribed in wt at levels mediated by the net negative influence of CYC8 and the positive influence of SNF2. In all cases, co-regulated genes located nearest to telomeres are subject to the most robust regulation by Swi-Snf and Tup1-Cyc8. ChIP analysis suggests that Snf2p and Cyc8p are present at both the active and inactive co-regulated genes in wt, where SNF2 is required for full Tup1p occupancy. We show that Snf2p and Cyc8p can directly interact with each other, most likely in the context of their respective complexes, suggesting that Swi-Snf and Tup1-Cyc8 are present together at co-regulated genes. We demonstrate that the nucleosome remodelling activities by Swi-Snf and Tup1-Cyc8 are specific to each target gene and extend over the available upstream intergenic region, the length of which is dependent upon the genes chromosomal context. Together, these data/ provide a deeper insight into the interplay between Tup1-Cyc8 and Swi-Snf upon transcription regulation and /suggest their occupancy and activity are intimately intertwined to yield the target gene transcriptional outcome via chromosomal location-dependent chromatin remodelling covering the available upstream gene regions.

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 30Â°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.

Dataset Information

Swi-Snf and Tup1-Cyc8 directly cooperate to antagonistically regulate gene transcription in yeast

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets