Project description:Histone acetylation and deacetylation are among the principal mechanisms by which chromatin is regulated during transcription, DNA silencing, and DNA repair. We analyzed patterns of genetic interactions uncovered during comprehensive genome-wide analyses in yeast to probe how histone acetyltransferase (HAT) and histone deacetylase (HDAC) protein complexes interact. The genetic interaction data unveil an underappreciated role of HDACs in maintaining cellular viability, and led us to show that deacetylation of the histone variant Htz1p at lysine 14 is mediated by Hda1p. Studies of the essential nucleosome acetyltransferase of H4 (NuA4) revealed acetylation-dependent protein stabilization of Yng2p, a potential nonhistone substrate of NuA4 and Rpd3C, and led to a new functional organization model for this critical complex. We also found that DNA double-stranded breaks (DSBs) result in local recruitment of the NuA4 complex, followed by an elaborate NuA4 remodeling process concomitant with Rpd3p recruitment and histone deacetylation. These new characterizations of the HDA and NuA4 complexes demonstrate how systematic analyses of genetic interactions may help illuminate the mechanisms of intricate cellular processes. Keywords: genetic modification The 44 datasets in this Series profiled the genome-wide genetic interactions for query genes encoding either HAT and HDAC catalytic subunits or subunits of the associated protein complexes. Of the 32 query genes, 5 were essential and were tested as temperature-sensitive (ts) alleles at three or more temperatures. (ESA1 was also tested as a hypomorphic allele.) The other query genes were tested as null deletion alleles derived from the Yeast Knockout strain collection.
Project description:Histone acetylation and deacetylation are among the principal mechanisms by which chromatin is regulated during transcription, DNA silencing, and DNA repair. We analyzed patterns of genetic interactions uncovered during comprehensive genome-wide analyses in yeast to probe how histone acetyltransferase (HAT) and histone deacetylase (HDAC) protein complexes interact. The genetic interaction data unveil an underappreciated role of HDACs in maintaining cellular viability, and led us to show that deacetylation of the histone variant Htz1p at lysine 14 is mediated by Hda1p. Studies of the essential nucleosome acetyltransferase of H4 (NuA4) revealed acetylation-dependent protein stabilization of Yng2p, a potential nonhistone substrate of NuA4 and Rpd3C, and led to a new functional organization model for this critical complex. We also found that DNA double-stranded breaks (DSBs) result in local recruitment of the NuA4 complex, followed by an elaborate NuA4 remodeling process concomitant with Rpd3p recruitment and histone deacetylation. These new characterizations of the HDA and NuA4 complexes demonstrate how systematic analyses of genetic interactions may help illuminate the mechanisms of intricate cellular processes. Keywords: genetic modification
Project description:Specific histone modifications play important roles in chromatin functions such as activation or repression of gene transcription. These participation must occur as a dynamic process, however, most of histone modification state maps reported to date only provide static pictures linking certain modification with active or silenced states. This study focused on the global histone modification variation that occurs in response to transcriptional reprogramming produced by a physiological perturbation in yeast. We have performed genome-wide chromatin immunoprecipitation analysis for eight specific histone modifications before and after of a saline stress. The most striking change is a quick deacetylation of lysines 9 and 14 of H3 and lysine 8 of H4 associated to repression of genes. Genes that are activated increase the acetylation levels at these same sites, but this acetylation process of activated genes seems minor quantitatively to that of the deacetylation of repressed genes. The observed changes in tri-methylation of lysines 4, 36 and 79 of H3 and also di-methylation of lysine 79 of H3 are much more moderate than those of acetylation. Additionally, we have produced new genome-wide maps for six histone modifications at more than five times higher resolution of previous available data and analyzed for the first time in S. cerevisiae genome wide profiles of two more, acetylation of lysine 8 of H4 and di-methylation of lysine 79 of H3. In this research we have shown that dynamic of acetylation state of histones during activation or repression of transcription is a process much quicker than methylation and therefore the changes produced in the acetylation may affect methylation but the reverse path is not possible. The experiments described in this study compare ChIP with a histone modification antibody to a control ChIP with a core histone antibody. Budding yeast samples were analyzed in exponential growing conditions (YPD) or after 10 minutes of 0.4M NaCl stress. For each experiment 1 or 2 biological replicates were performed.
Project description:Dynamic acetylation of metabolic proteins has emerged as a ubiquitous post-translational modification of human metabolic proteins. However, the corresponding modifying enzymes and the functions of the modification await exploration. Using a genome-wide synthetic lethality screen, we constructed a genetic interaction network of human histone deacetylases (HDACs) and discovered many metabolic substrates of these enzymes. We further confirmed that the adenosine monophosphate-activated protein kinase (AMPK) catalytic subunit is acetylated and deacetylated by EP300 and HDAC1, respectively. Deacetylation of AMPK catalytic subunit enhances physical interaction with the upstream kinase LKB1, and leads to AMPK phosphorylation and activation. These findings highlight the importance of genetic interaction profiling to identify specific substrates of individual HDACs and elucidate how cells use protein (de)acetylation to coordinate nutrient availability and cellular energy status.
Project description:A network governing DNA integrity was identified in yeast by a global genetic analysis of synthetic fitness or lethality defect (SFL) interactions. Within this network, multiple functional modules or mini-pathways were defined according to their common patterns of global SFL interactions and available protein-protein interaction information. Modules or genes involved in DNA replication, DNA replication checkpoint signaling, and oxidative stress response were identified as the major guardians against lethal spontaneous DNA damage, efficient repair of which requires the functions of the DNA damage checkpoint signaling and multiple DNA repair pathways. This genome-wide genetic interaction network also revealed potential roles of a number of genes and modules in mitotic DNA replication and maintenance of genomic stability. These include DIA2, NPT1, HST3, HST4, and the CSM1/LRS4 module (CSM1m). Likewise, the CTF18 module (CTF18m), previously implicated in sister chromatid cohesion, was found to participate in the DNA replication checkpoint. Keywords: dose response
Project description:Gcn5 and sirtuins are conserved HAT and HDAC enzymes that were first characterised as regulators of gene expression via histone acetylation. Although histone tails are important substrates of these enzymes, they also target non-histone proteins in diverse processes. Previously, we used SILAC-based mass spectrometry to identify novel non-histone substrates of Gcn5 and sirtuins in yeast. We found a shared target consensus sequence. In our latest work we used a synthetic biology approach to demonstrate that this consensus sequence can direct acetylation and deacetylation targeting by these enzymes in vivo. We used the synthetic substrate as a tool to prioritize SILAC-based acetylome analyses of SAGA mutants. Presented here are analyses of ada3∆ mutants analyzed in this work versus wild-type control. The strains and labels used are described in the BioRxiv report linked in the methods sections below.
Project description:Linker histones play a fundamental role in shaping chromatin structure, but how their interaction with chromatin is controlled not well understood. In this study we used a combination of genetic and genomic approaches to explore the regulation of linker histone binding in the yeast, Saccharomyces cerevisiae. Despite the tight correlation between linker-to-core histone ratio and nucleosome repeat length (NRL) observed in many organisms, we found that increasing Hho1 levels did not change the overall NRL in yeast chromatin. While over-expression of Hho1 did not alter nucleosome spacing, it did result in a severe growth defect, which could be rescued by mutations that increased histone acetylation in the cell. Consistent with this, genome-wide analysis of linker histone occupancy revealed an inverse correlation with histone tail acetylation in both yeast and mouse embryonic stem cells. Collectively these results suggest that histone acetylation negatively regulates linker histone binding in S. cerevisiae and other organisms.
Project description:Specific histone modifications play important roles in chromatin functions such as activation or repression of gene transcription. These participation must occur as a dynamic process, however, most of histone modification state maps reported to date only provide static pictures linking certain modification with active or silenced states. This study focused on the global histone modification variation that occurs in response to transcriptional reprogramming produced by a physiological perturbation in yeast. We have performed genome-wide chromatin immunoprecipitation analysis for eight specific histone modifications before and after of a saline stress. The most striking change is a quick deacetylation of lysines 9 and 14 of H3 and lysine 8 of H4 associated to repression of genes. Genes that are activated increase the acetylation levels at these same sites, but this acetylation process of activated genes seems minor quantitatively to that of the deacetylation of repressed genes. The observed changes in tri-methylation of lysines 4, 36 and 79 of H3 and also di-methylation of lysine 79 of H3 are much more moderate than those of acetylation. Additionally, we have produced new genome-wide maps for six histone modifications at more than five times higher resolution of previous available data and analyzed for the first time in S. cerevisiae genome wide profiles of two more, acetylation of lysine 8 of H4 and di-methylation of lysine 79 of H3. In this research we have shown that dynamic of acetylation state of histones during activation or repression of transcription is a process much quicker than methylation and therefore the changes produced in the acetylation may affect methylation but the reverse path is not possible.
Project description:Transcriptional memory is critical for the faster reactivation of necessary genes upon environmental changes and requires that the genes were previously in an active state. However, whether transcriptional repression also displays “memory” of the prior transcriptionally inactive state remains unknown. In this study, we show that transcriptional repression of approximately 540 genes in yeast occurs much more rapidly if the genes have been previously repressed during carbon source shifts. This novel transcriptional response has been termed transcriptional repression memory(TREM). Interestingly, Rpd3L histone deacetylase (HDAC), targeted to active promoters induces TREM. Mutants for Rpd3L exhibit increased acetylation at active promoters and delay TREM and RNA PolII dissociation significantly. Surprisingly, the interaction between H3K4me3 and Rpd3L via the Pho23 PHD finger is sufficient to induce histone deacetylation and TREM by Rpd3L. Therefore, we propose that an active mark, H3K4me3 enriched at promoters, instructs Rpd3L HDAC to induce histone deacetylation and TREM.
Project description:HDAC inhibitors are thought to regulate gene expression by post-translational modification of histone as well as non-histone proteins. Often studied at single loci, increased histone acetylation is the paradigmatic mechanism of action, however, little is known of the extent of genome-wide changes of the mammalian genome when stimulated by the hydroxamic acids, TSA and SAHA. In primary human vascular endothelial cells we map the chromatin modifications, histone H3 acetylation of lysine 9 and 14 (H3K9/14ac) using chromatin immunoprecipitation (ChIP) coupled with massive parallel sequencing (ChIP-seq). Since acetylation mediated gene expression is often associated with modification of other lysine residues we also examined H3K4me3 and H3K9me3 as well as changes in CpG methylation (CpG-seq). Genome-wide mRNA sequencing indicates the differential expression of about 30% of genes, with almost equal numbers being up- and down- regulated. We observe deacetylation conferred by TSA and SAHA that are associated with decreased gene expression. Histone deacetylation is associated with the loss of p300/CBP binding at gene promoters. This study provides an important framework for HDAC inhibitor function in vascular biology and a comprehensive description of genome-wide deacetylation. Mouse ChIP-seq profiles for histone acetylation treated and control samples were generated by deep sequencing, using Illumina GAIIx.