Dataset Information

Structure of the Hir histone chaperone complex

ABSTRACT: The evolutionarily conserved HIRA/Hir histone chaperone complex and ASF1/Asf1 co-chaperone cooperate for replication-independent chromatin assembly. Here we report the molecular architecture of the Hir complex with Asf1/H3/H4 via single-particle cryo-EM and crosslinking mass spectrometry.

INSTRUMENT(S): Q Exactive HF

ORGANISM(S): Saccharomyces Cerevisiae (baker's Yeast)

SUBMITTER: Hee Jong Kim

LAB HEAD: Benjamin Aaron Garcia

PROVIDER: PXD040705 | Pride | 2024-08-22

REPOSITORIES: Pride

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			Action	DRS
	20190510-hjk-DSBU-4-dialyzed-hir-complex-preSEC-inj1-rt100.mzML	Mzml
	20190510-hjk-DSBU-4-dialyzed-hir-complex-preSEC-inj1-rt100.raw	Raw
	20190510-hjk-DSBU-4-dialyzed-hir-complex-preSEC-inj2-rt205-previous-method.mzML	Mzml
	20190510-hjk-DSBU-4-dialyzed-hir-complex-preSEC-inj2-rt205-previous-method.raw	Raw
	20190510-hjk-DSBU-4-dialyzed-hir-complex-preSEC-inj2-rt205.mzML	Mzml

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Structure of the Hir histone chaperone complex.

Kim Hee Jong HJ Szurgot Mary R MR van Eeuwen Trevor T Ricketts M Daniel MD Basnet Pratik P Zhang Athena L AL Vogt Austin A Sharmin Samah S Kaplan Craig D CD Garcia Benjamin A BA Marmorstein Ronen R Murakami Kenji K

Molecular cell 20240625 14

The evolutionarily conserved HIRA/Hir histone chaperone complex and ASF1a/Asf1 co-chaperone cooperate to deposit histone (H3/H4)<sub>2</sub> tetramers on DNA for replication-independent chromatin assembly. The molecular architecture of the HIRA/Hir complex and its mode of histone deposition have remained unknown. Here, we report the cryo-EM structure of the S. cerevisiae Hir complex with Asf1/H3/H4 at 2.9-6.8 Å resolution. We find that the Hir complex forms an arc-shaped dimer with a Hir1/Hir2/H ...[more]

PMID: 38925115

Similar Datasets

Project description:Histones are the protein components of the basic unit of chromatin, the core particle of the nucleosome. They play a central role in defining chromatin states associated with distinct cell fates and are classified into replicative and non-replicative/replacement histone variants. While the latter do not exhibit S phase regulation in their expression, the replicative histone variants show a major peak in expression early during S phase to support chromatin assembly during replication of the genome. Their expression is tightly regulated during the cell-cycle both transcriptionally and post-transcriptionally and involves a number of actors. During replication in human cells, two main chaperones ensure the deposition of H3-H4 onto DNA: Chromatin assembly factor 1 (CAF-1) and Anti-silencing factor 1 (ASF1). Interestingly, on the one hand, ASF1 binds the newly synthesized replicative histones H3.1/H3.2-H4 to hand them off to the downstream chaperone, CAF-1, for deposition onto the duplicated DNA strands in a DNA synthesis-coupled (DSC) manner. On the other hand, ASF1 also promotes the recycling of parental histones during replication. In addition, ASF1 binds the non-replicative variant H3.3 and hands it off to the downstream chaperone Histone regulator A (HIRA) for deposition of H3.3 in a DNA synthesis independent (DSI) manner. Finally, in human cells, ASF1 but not CAF-1, also provides a buffering system for histone excess generated in response to stalled replication, indicating yet another role for ASF1 in regulating the flow of replicative histones in higher eukaryotes. However, to date, roles of these chaperones in histone RNA metabolism in mammals had remained unexplored. This is particularly interesting to consider given that in budding yeast, where there are no distinct replicative and non-replicative H3 variants, the single ASF1 ortholog participates in activating transcription of histone genes in S phase and transcriptional repression outside S phase in combination with Hir1, the budding yeast counterpart of HIRA. We thus decided to explore how the key histone chaperones involved in DNA synthesis-coupled chromatin assembly could contribute to the critical regulation of expression of replicative histone genes in human cells during S phase. From total RNA extracted from asynchronous and synchronized human cells, we performed RNA-seq and found that most of the annotated replicative histone genes decreased in expression upon ASF1 depletion by siRNA during S phase compared to the control condition with siRNA againt GFP. However, by 4sU-labeled RNA-seq we detected an increase in newly synthesized replicative histone transcripts. These findings indicate that the decrease in expression of replicative histone genes in ASF1-depleted cells cannot be due to a decrease at the level of transcription. We then inspected closely the sequences at the 3’ end of the replicative histone transcripts in our RNA-seq data and detected a defect of their 3’ processing. Thus, we propose that in mammals ASF1 plays a role in the unique regulation of replicative histone RNA metabolism.