Project description:Spt6 is a conserved factor, critically required for several transcription and chromatin related processes. We now show that Spt6 and its binding partner, Iws1, are required for heterochromatic silencing in Schizosaccharomyces pombe. Our studies demonstrate that Spt6 is required for silencing of all heterochromatic loci and that an spt6 mutant has an unusual combination of heterochromatic phenotypes compared to previously studied silencing mutants. Unexpectedly, we find normal nucleosome positioning over heterochromatin and normal levels of histone H3K9 dimethylation. However, we also find greatly reduced levels of H3K9 trimethylation, elevated levels of H3K14 acetylation, and reduced recruitment of several silencing factors. Our evidence suggests that Spt6 plays a role at both the transcriptional and post-transcriptional levels; in an spt6 mutant, RNA polymerase II (RNAPII) occupancy at the pericentric regions is only modestly increased, while production of small interfering RNAs (siRNAs) is lost. Taken together, our results suggest that Spt6 is required for multiple steps in heterochromatic silencing by controlling chromatin, transcriptional, and post-transcriptional processes.
Project description:Histone acetylation and deacetylation is important for gene regulation. The histone acetyltransferase, Gcn5, is a known activator of transcriptional initiation that is recruited to gene promoters. Here we map genome-wide levels of Gcn5 occupancy and histone H3K14ac at high resolution. Gcn5 is predominantly localized to coding regions of highly transcribed genes where it antagonistically collaborates with the class II histone deacetylase, Clr3, to regulate histone H3K14ac levels. Regulation of histone H3k14ac levels is critical for regulation of many genes during stress adaptation. Our findings suggest a novel role for Gcn5 during transcriptional elongation in addition to its known role in transcriptional initiation. The data in this series showed Gcn5 occupancy and H3K14 acetylation levels in wild type, gcn5- and gcn5-/clr3- cells under KCl stress condition. Related expression data are GSE5227 and GSE13817 Keywords: Chip-chip
Project description:The histone acetyltransferase Mst2 prevents epigenetic silencing via specific acetylation of the ubiquitin ligase Brl1 [microarray data]
Project description:Histone H3 lysine9 acetylation, rather than lysine4 trimethylation, marks meiotic recombination hotspots and promotes recombination initiation in fission yeast
