Project description:Nucleosome assembly in vivo requires assembly factors, such as histone chaperones, to bind to histones and mediate their deposition onto DNA. In yeast, the essential histone chaperone FACT (FAcilitates Chromatin Transcription) functions in nucleosome assembly and H2A-H2B deposition during transcription elongation and DNA replication. Recent studies have identified candidate histone residues that mediate FACT binding to histones, but it is not known which histone residues are important for FACT to deposit histones onto DNA during nucleosome assembly. In this study, we report that the histone H2B repression (HBR) domain within the H2B N-terminal tail is important for histone deposition by FACT. Deletion of the HBR domain causes significant defects in histone occupancy in the yeast genome, particularly at HBR-repressed genes, and a pronounced increase in H2A-H2B dimers that remain bound to FACT in vivo. Moreover, the HBR domain is required for purified FACT to efficiently assemble recombinant nucleosomes in vitro. We propose that the interaction between the highly basic HBR domain and DNA plays an important role in stabilizing the nascent nucleosome during the process of histone H2A-H2B deposition by FACT. 6 samples, 2 inputs and 4 ChIP samples for histone H2B (2 for wild-type and 2 for an H2B â30-37 mutant)
Project description:Nucleosome assembly in vivo requires assembly factors, such as histone chaperones, to bind to histones and mediate their deposition onto DNA. In yeast, the essential histone chaperone FACT (FAcilitates Chromatin Transcription) functions in nucleosome assembly and H2A-H2B deposition during transcription elongation and DNA replication. Recent studies have identified candidate histone residues that mediate FACT binding to histones, but it is not known which histone residues are important for FACT to deposit histones onto DNA during nucleosome assembly. In this study, we report that the histone H2B repression (HBR) domain within the H2B N-terminal tail is important for histone deposition by FACT. Deletion of the HBR domain causes significant defects in histone occupancy in the yeast genome, particularly at HBR-repressed genes, and a pronounced increase in H2A-H2B dimers that remain bound to FACT in vivo. Moreover, the HBR domain is required for purified FACT to efficiently assemble recombinant nucleosomes in vitro. We propose that the interaction between the highly basic HBR domain and DNA plays an important role in stabilizing the nascent nucleosome during the process of histone H2A-H2B deposition by FACT.
Project description:CPC-NCP complexes were crosslinked using EDC and analysed by mass spectrometry. The results showed Borealin is critical for nucleosome binding made extensive contacts with NCPs, whereas Survivin interactions are mostly limited to the BIR domain and the H3 N-terminal tail as expected. Mapping the crosslinks onto the three dimensional structures of NCP and CPC suggests a model where the localisation module of the CPC together with a highly basic N-terminal tail of Borealin docks onto the acidic patch formed by H2A and H2B, a surface commonly involved in nucleosome recognition. This interaction may orient the Survivin BIR domain to facilitate binding of histone H3 tail phosphorylated at Thr3. Notably, Borealin loop residues trace along the DNA-histone interface implying its major contribution to nucleosome binding involves both protein-histone and possibly protein-DNA contacts.
Project description:Histone acetylation is important for the activation of gene transcription but little is known about its direct ‘read/write’ mechanisms. Here, we report cryo-electron microscopy structures in which a p300/CBP multidomain monomer recognizes histone H4 N-terminal tail (NT) acetylation (ac) in a nucleosome and acetylates non-H4 histone NTs within the same nucleosome. p300/CBP not only recognized H4NTac via the bromodomain pocket responsible for ‘reading’, but also interacted with the DNA minor grooves via the outside of that pocket. This directed the catalytic center of p300/CBP to one of the non-H4 histone NTs. The primary target that p300 ‘writes’ by ‘reading’ H4NTac was H2BNT, and H2BNTac promoted H2A-H2B dissociation from the nucleosome. We propose a model in which p300/CBP ‘replicates’ histone NT acetylation within the H3-H4 tetramer to inherit epigenetic storage, and ‘transcribes’ it from the H3-H4 tetramer to the H2B-H2A dimers to activate context-dependent gene transcription through local nucleosome destabilization.
Project description:Histone H2B was mutated to give H2B^3-32. Total RNA from three replicate cultures of wild-type and mutant was isolated and the expression profiles were determined using Affymetrix arrays. Comparisons between the sample groups allow the identification of genes regulated by H2B N-terminal domain. Experiment Overall Design: mutant compared to wild-type, 3 replicates
Project description:Histone H2B was mutated to give H2B^3-37. Total RNA from three replicate cultures of wild-type and mutant was isolated and the expression profiles were determined using Affymetrix arrays. Comparisons between the sample groups allow the identification of genes regulated by H2B N-terminal domain. Experiment Overall Design: mutant compared to wild-type, 3 replicates
Project description:The heterodimeric histone chaperone FACT consisting of SSRP1 and SPT16 contributes to dynamic nucleosome rearrangements during various DNA-dependent processes including transcription. In search of post-translational modifications that may regulate the activity of FACT, SSRP1 and SPT16 were isolated from Arabidopsis cells and analysed by mass spectrometry. Four acetylated lysine residues could be mapped within the basic C-terminal region of SSRP1, while three phosphorylated serine/threonine residues were identified in the acidic C-terminal region of SPT16. Mutational analysis of the SSRP1 acetylation sites revealed only mild effects. However, phosphorylation of SPT16 that is catalysed by protein kinase CK2, modulates histone interactions. A non-phosphorylatable version of SPT16 displayed reduced histone binding and (unlike the phosphorylatable wild-type and phosphomimic versions) proved inactive in complementing the growth and developmental phenotypes of spt16 mutant plants. In plants expressing the non-phosphorylatable SPT16 version we detected at a subset of genes enrichment of histone H3 directly upstream of RNA polymerase II transcriptional start sites (TSSs) in a region that usually is nucleosome-depleted. This is associated with altered transcript levels, suggesting that some genes require phosphorylation of the SPT16 acidic region for establishing the correct nucleosome occupancy at the TSS as a prerequisite for proper transcription.
Project description:Histone H2B was mutated to give H2B^3-32, H2B K->G, H2B^3-37, and H2B^30-37. Total RNA from three replicate cultures of wild-type and mutant was isolated and the expression profiles were determined using Affymetrix arrays. Comparisons between the sample groups allow the identification of genes regulated by H2B HBR domain. Experiment Overall Design: mutants compared to wild-type, 3 replicates Experiment Overall Design: This reference Series links data in the following related Series: Experiment Overall Design: GSE3802 Histone H2B^3-32 Experiment Overall Design: GSE3803 Histone H2B K->G Experiment Overall Design: GSE3804 Histone H2B^3-37 Experiment Overall Design: GSE3805 Histone H2B^3-37
Project description:Using histone H3 mutants designed so that they can only form a heterodimer, we studied the gene expression in a collection of mutants, comparing mutations to one histone H3 tail of a nucleosome compared to two histone H3 tails of a nucleosome.