Project description:Nucleosomes in all eukaryotes examined to date adopt a characteristic architecture within genes and play fundamental roles in regulating transcription, yet the identity and precise roles of many of the trans-acting factors responsible for the establishment and maintenance of this organization remain to be identified. We profiled a compendium of 50 yeast strains carrying conditional alleles or complete deletions of genes involved in transcriptional regulation, histone biology and chromatin remodeling, as well as compounds that target transcription and histone deacetylases, to assess their respective roles in nucleosome positioning and transcription. We find that nucleosome patterning in genes is affected by many factors including the CAF-1 complex, Spt10 and Spt21, in addition to previously reported remodeler ATPases and histone chaperones. Disruption of these factors or reductions in histone levels led genic nucleosomes to assume positions more consistent with their intrinsic sequence preferences, with pronounced and specific shifts of the +1 nucleosome relative to the transcription start site. These shifts of +1 nucleosomes appear to have functional consequences, as several affected genes in Ino80 mutants exhibited altered expression responses. Our parallel expression profiling compendium revealed extensive transcription changes in intergenic and antisense regions, most of which occur in regions with altered nucleosome occupancy and positioning. We show that the nucleosome-excluding transcription factors Reb1, Abf1, Tbf1, and Rsc3 suppress cryptic transcripts at their target promoters, while a combined analysis of nucleosome and expression profiles identified 36 novel transcripts that are normally repressed by Tup1/Cyc8. Our data confirm and extend the roles of chromatin remodelers and chaperones as major determinants of genic nucleosome positioning and these data provide a valuable resource for future studies. We examined 50 single-gene loss-of-function strains, comprised of gene deletions (del) and temperature-sensitive (ts) or tetracycline promoter-shutoff (tet) alleles. These genes were selected based on their known or potential role in nucleosome biology and include remodeler ATPases and chaperones, histones and histone modifiers, transcription and elongation factors, and components of RNA polymerase I and II. The compendium also includes 4 compounds targeting transcription and histone deacetylases, as well as a histone depletion time course performed with a strain in which H4 gene expression is exclusively under the control of a GAL1 promoter. Genome-wide nucleosome occupancy profiles were generated using Affymetrix Tiling arrays with probes spaced every 4 bp [PMID:16569694], or next-generation sequencing. Identically prepared samples for each strain and treatment were analyzed on the same tiling arrays for strand-specific expression differences. Each compendium condition was compared to a matched wild-type (WT) reference grown in parallel.

Project description:We have characterized two post-translational histone modifications in C. elegans on a genomic scale. Micrococcal nuclease digestion and immunoprecipitation were used to obtain distinct populations of single nucleosome cores, which were analyzed using massively parallel DNA sequencing to obtain positional and coverage maps. Two methylated histone H3 populations were chosen for comparison: H3K4 histone methylation (associated with active chromosomal regions) and H3K9 histone methylation (associated with inactivity). From analysis of the sequence data, we found nucleosome cores with these modifications to be enriched in two distinct partitions of the genome; H3K4 methylation was particularly prevalent in promoter regions of widely-expressed genes while H3K9 methylation was enriched on specific chromosomal arms. For each of the six chromosomes, the highest level of H3K9 methylation corresponds to the pairing center responsible for chromosome alignment during meiosis. H3K9 enrichment at pairing centers appears to be an early mark in meiotic chromosome sorting, occurring in the absence of components required for proper pairing of homologous chromosomes. H3K9 methylation shows an intricate pattern within the chromosome arms, with a particular anti-correlation to regions that display a strong ~10 bp periodicity of AA/TT dinucleotides that is known to associate with germline trancription. By contrast to the global features observed with H3K9 methylation, H3K4 methylation profiles were most striking in their local characteristics around promoters, providing a unique promoter-central landmark for 3903 C. elegans genes and allowing a precise analysis of nucleosome positioning in the context of transcriptional initiation. Keywords: epigenetics Examination of total nucleosome and nucleosomes with 2 different histone modifications in C. elegans. 5 samples are analyzed: 1. total mononucleosome core DNA from C. elegans wild type strain N2, 2. anti-H3K4me2/3 precipitated mononucleosome core DNA from C. elegans wild type strain N2, 3. anti-H3K9me3 precipitated mononucleosome core DNA from C. elegans wild type strain N2, 4. total mononucleosome core DNA from C. elegans mutant strain zim-2(tm-574), 5. anti-H3K9me3 precipitated mononucleosome core DNA from C. elegans mutant strain zim-2(tm-574)

Project description:Nucleosomes in all eukaryotes examined to date adopt a characteristic architecture within genes and play fundamental roles in regulating transcription, yet the identity and precise roles of many of the trans-acting factors responsible for the establishment and maintenance of this organization remain to be identified. We profiled a compendium of 50 yeast strains carrying conditional alleles or complete deletions of genes involved in transcriptional regulation, histone biology and chromatin remodeling, as well as compounds that target transcription and histone deacetylases, to assess their respective roles in nucleosome positioning and transcription. We find that nucleosome patterning in genes is affected by many factors including the CAF-1 complex, Spt10 and Spt21, in addition to previously reported remodeler ATPases and histone chaperones. Disruption of these factors or reductions in histone levels led genic nucleosomes to assume positions more consistent with their intrinsic sequence preferences, with pronounced and specific shifts of the +1 nucleosome relative to the transcription start site. These shifts of +1 nucleosomes appear to have functional consequences, as several affected genes in Ino80 mutants exhibited altered expression responses. Our parallel expression profiling compendium revealed extensive transcription changes in intergenic and antisense regions, most of which occur in regions with altered nucleosome occupancy and positioning. We show that the nucleosome-excluding transcription factors Reb1, Abf1, Tbf1, and Rsc3 suppress cryptic transcripts at their target promoters, while a combined analysis of nucleosome and expression profiles identified 36 novel transcripts that are normally repressed by Tup1/Cyc8. Our data confirm and extend the roles of chromatin remodelers and chaperones as major determinants of genic nucleosome positioning and these data provide a valuable resource for future studies. We examined 50 single-gene loss-of-function strains, comprised of gene deletions (del) and temperature-sensitive (ts) or tetracycline promoter-shutoff (tet) alleles. These genes were selected based on their known or potential role in nucleosome biology and include remodeler ATPases and chaperones, histones and histone modifiers, transcription and elongation factors, and components of RNA polymerase I and II. The compendium also includes 4 compounds targeting transcription and histone deacetylases, as well as a histone depletion time course performed with a strain in which H4 gene expression is exclusively under the control of a GAL1 promoter. Genome-wide nucleosome occupancy profiles were generated using Affymetrix Tiling arrays with probes spaced every 4 bp [PMID:16569694], or next-generation sequencing. Identically prepared samples for each strain and treatment were analyzed on the same tiling arrays for strand-specific expression differences. Each compendium condition was compared to a matched wild-type (WT) reference grown in parallel.

			Action	DRS
	MaxQuant_Output.zip	Other
	UP000005640_9606.fasta	Fasta
	b015p038NNN15F_01.raw	Raw
	b015p038NNN15F_02.raw	Raw
	b015p038NNN15R_01.raw	Raw

Dataset Information

H4K20me2 SILAC Nucleosome Affinity Purification

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H4K20me0 recognition by BRCA1-BARD1 directs homologous recombination to sister chromatids.

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