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Keishi Shintomi, Fukashi Inoue, Hiroshi Watanabe, Keita Ohsumi, Miho Ohsugi, Tatsuya Hirano
The nucleosome is the fundamental structural units of eukaryotic chromatin. During mitosis, duplicated nucleosome fibers are organized into a pair of rod-shaped structures (chromatids) within a mitotic chromosome. However, it remains unclear whether nucleosome assembly is indeed an essential prerequisite for mitotic chromosome assembly. Here, we combined mouse sperm nuclei and Xenopus cell-free egg extracts depleted of the histone chaperone Asf1 and found that chromatid-like structures could be assembled even in the near-absence of nucleosomes...
May 18, 2017: Science
Meng-Ying Wu, Chia-Yeh Lin, Hsin-Yi Tseng, Fei-Man Hsu, Pao-Yang Chen, Cheng-Fu Kao
Heterochromatin is a heritable form of gene repression, with critical roles in development and cell identity. Understanding how chromatin factors results in such repression is a fundamental question. Chromatin is assembled and disassembled during transcription, replication and repair by anti-silencing function 1 (Asf1), a highly conserved histone chaperone. Transcription and DNA replication are also affected by histone modifications that modify nucleosome dynamics, such as H2B ubiquitylation (H2Bub). We report here that H2Bub and Asf1 cooperatively promote transcriptional silencing at yeast telomeres and mating loci...
May 17, 2017: Nucleic Acids Research
Ruibin Zhu, Mari Iwabuchi, Keita Ohsumi
Histone chaperones are a group of histone-binding proteins that facilitate the assembly of nucleosomes, the fundamental structural units of chromatin in eukaryotes. In nucleosome assembly, deposition of a histone H3-H4 tetramer onto DNA is the first and critical step, which is mediated by the histone chaperones HIRA and CAF-1. HIRA and CAF-1 are reportedly involved in DNA replication independent (RI) and replication coupled nucleosome assembly, respectively. However, the mechanisms by which they mediate histone deposition remain unclear...
2017: Cell Structure and Function
Catherine Fromental-Ramain, Philippe Ramain, Ali Hamiche
Histone variants are non-allelic isoforms of canonical histones and they are deposited, in contrast to canonical histones, in a replication-independent (RI) manner. RI deposition of H3.3, a histone variant from the H3.3 family, is mediated in mammals by distinct pathways involving either the histone regulator A (HIRA) complex or the death-associated protein (DAXX)/α-thalassemia X-linked mental retardation protein (ATRX) complex. Here, we investigated the function of Drosophila DAXX Like Protein (DLP) by using both fly genetics approaches and protein biochemistry...
March 20, 2017: Molecular and Cellular Biology
Andrew Bowman, Akiko Koide, Jay S Goodman, Meaghan E Colling, Daria Zinne, Shohei Koide, Andreas G Ladurner
Histone chaperones are proteins that interact with histones to regulate the thermodynamic process of nucleosome assembly. sNASP and ASF1 are conserved histone chaperones that interact with histones H3 and H4 and are found in a multi-chaperoning complex in vivo Previously we identified a short peptide motif within H3 that binds to the TPR domain of sNASP with nanomolar affinity. Interestingly, this peptide motif is sequestered within the known ASF1-H3-H4 interface, raising the question of how these two proteins are found in complex together with histones when they share the same binding site...
January 25, 2017: Nucleic Acids Research
Pradyut K Paul, Mary E Rabaglia, Chen-Yu Wang, Donald S Stapleton, Ning Leng, Christina Kendziorski, Peter W Lewis, Mark P Keller, Alan D Attie
Anti-silencing function 1 (ASF1) is a histone H3-H4 chaperone involved in DNA replication and repair, and transcriptional regulation. Here, we identify ASF1B, the mammalian paralog to ASF1, as a proliferation-inducing histone chaperone in human β-cells. Overexpression of ASF1B led to distinct transcriptional signatures consistent with increased cellular proliferation and reduced cellular death. Using multiple methods of monitoring proliferation and mitotic progression, we show that overexpression of ASF1B is sufficient to induce human β-cell proliferation...
December 2016: Cell Cycle
Lei Fang, Danqi Chen, Clinton Yu, Hongjie Li, Jason Brocato, Lan Huang, Chunyuan Jin
Acrolein is a major component of cigarette smoke and cooking fumes. Previously, we reported that acrolein compromises chromatin assembly; however, underlying mechanisms have not been defined. Here, we report that acrolein reacts with lysine residues, including lysines 5 and 12, sites important for chromatin assembly, on histone H4 in vitro and in vivo Acrolein-modified histones are resistant to acetylation, suggesting that the reduced H4K12 acetylation that occurs following acrolein exposure is probably due to the formation of acrolein-histone lysine adducts...
December 1, 2016: Molecular and Cellular Biology
Brandon Wyse, Roxanne Oshidari, Hollie Rowlands, Sanna Abbasi, Krassimir Yankulov
Chromatin structures are transmitted to daughter cells through a complex system of nucleosome disassembly and re-assembly at the advancing replication forks. However, the role of replication pausing in the transmission and perturbation of chromatin structures has not been addressed. RRM3 encodes a DNA helicase, which facilitates replication at sites covered with non-histone protein complexes (tRNA genes, active gene promoters, telomeres) in Saccharomyces cerevisiae. In this report we show that the deletion of RRM3 reduces the frequency of epigenetic conversions in the subtelomeric regions of the chromosomes...
July 3, 2016: Nucleus
Zachary P Schaefer, Lucas J Bailey, Anthony A Kossiakoff
Engineering monovalent Fab fragments into bivalent formats like IgGs or F(ab')2 can lead to aggregation presumably because of nonspecific off-target interactions that induce aggregation. In an effort to further understand the molecular determinants of nonspecific interactions for engineered antibodies and natively folded proteins in general, we focused on a synthetic Fab with low nanomolar affinity to histone chaperone Anti-silencing factor 1 (Asf1) that demonstrates off-target binding through low solubility (∼5 mg/mL) in the multivalent F(ab') 2 state...
July 2016: Protein Science: a Publication of the Protein Society
Michael Tsabar, David P Waterman, Fiona Aguilar, Lizabeth Katsnelson, Vinay V Eapen, Gonen Memisoglu, James E Haber
To allow for sufficient time to repair DNA double-stranded breaks (DSBs), eukaryotic cells activate the DNA damage checkpoint. In budding yeast, Rad53 (mammalian Chk2) phosphorylation parallels the persistence of the unrepaired DSB and is extinguished when repair is complete in a process termed recovery or when the cells adapt to the DNA damage checkpoint. A strain containing a slowly repaired DSB does not require the histone chaperone Asf1 to resume cell cycle progression after DSB repair. When a second, rapidly repairable DSB is added to this strain, Asf1 becomes required for recovery...
May 15, 2016: Genes & Development
Colin M Hammond, Ramasubramanian Sundaramoorthy, Mark Larance, Angus Lamond, Michael A Stevens, Hassane El-Mkami, David G Norman, Tom Owen-Hughes
Vps75 is a histone chaperone that has been historically characterized as homodimer by X-ray crystallography. In this study, we present a crystal structure containing two related tetrameric forms of Vps75 within the crystal lattice. We show Vps75 associates with histones in multiple oligomers. In the presence of equimolar H3-H4 and Vps75, the major species is a reconfigured Vps75 tetramer bound to a histone H3-H4 tetramer. However, in the presence of excess histones, a Vps75 dimer bound to a histone H3-H4 tetramer predominates...
July 27, 2016: Nucleic Acids Research
Yoav Voichek, Raz Bar-Ziv, Naama Barkai
Genome replication introduces a stepwise increase in the DNA template available for transcription. Genes replicated early in S phase experience this increase before late-replicating genes, raising the question of how expression levels are affected by DNA replication. We show that in budding yeast, messenger RNA (mRNA) synthesis rate is buffered against changes in gene dosage during S phase. This expression homeostasis depends on acetylation of H3 on its internal K56 site by Rtt109/Asf1. Deleting these factors, mutating H3K56 or up-regulating its deacetylation, increases gene expression in S phase in proportion to gene replication timing...
March 4, 2016: Science
S Messiaen, J Guiard, C Aigueperse, I Fliniaux, S Tourpin, V Barroca, I Allemand, P Fouchet, G Livera, M Vernet
Anti-silencing function 1 (ASF1) is an evolutionarily conserved histone H3-H4 chaperone involved in the assembly/disassembly of nucleosome and histone modification. Two paralogous genes, Asf1a and Asf1b, exist in the mouse genome. Asf1a is ubiquitously expressed and its loss causes embryonic lethality. Conversely, Asf1b expression is more restricted and has been less studied. To determine the in vivo function of Asf1b, we generated a Asf1b-deficient mouse line (Asf1b(GT(ROSA-βgeo)437)) in which expression of the lacZ reporter gene is driven by the Asf1b promoter...
May 2016: Reproduction: the Official Journal of the Society for the Study of Fertility
Hongfang Qiu, Răzvan V Chereji, Cuihua Hu, Hope A Cole, Yashpal Rawal, David J Clark, Alan G Hinnebusch
Chaperones, nucleosome remodeling complexes, and histone acetyltransferases have been implicated in nucleosome disassembly at promoters of particular yeast genes, but whether these cofactors function ubiquitously, as well as the impact of nucleosome eviction on transcription genome-wide, is poorly understood. We used chromatin immunoprecipitation of histone H3 and RNA polymerase II (Pol II) in mutants lacking single or multiple cofactors to address these issues for about 200 genes belonging to the Gcn4 transcriptome, of which about 70 exhibit marked reductions in H3 promoter occupancy on induction by amino acid starvation...
February 2016: Genome Research
Thiago Cesar Prata Ramos, Vinicius Santana Nunes, Sheila Cristina Nardelli, Bruno dos Santos Pascoalino, Nilmar Silvio Moretti, Antonio Augusto Rocha, Leonardo da Silva Augusto, Sergio Schenkman
The histone H4 from Trypanosomatids diverged from other eukaryotes in the N-terminus, a region that undergoes post-translation modifications involved in the control of gene expression, DNA replication, and chromatin assembly. Nonetheless, the N-terminus of Trypanosoma cruzi histone H4 is mainly acetylated at lysine 4. The lysines 10 and 14 are also acetylated, although at less extent, increasing during the S-phase or after DNA damage, which suggests a regulatory function. Here, we investigated the roles of these acetylations by expressing non-acetylated forms of histone H4 in T...
November 2015: Molecular and Biochemical Parasitology
Eric I Campos, Arne H Smits, Young-Hoon Kang, Sébastien Landry, Thelma M Escobar, Shruti Nayak, Beatrix M Ueberheide, Daniel Durocher, Michiel Vermeulen, Jerard Hurwitz, Danny Reinberg
Despite minimal disparity at the sequence level, mammalian H3 variants bind to distinct sets of polypeptides. Although histone H3.1 predominates in cycling cells, our knowledge of the soluble complexes that it forms en route to deposition or following eviction from chromatin remains limited. Here, we provide a comprehensive analysis of the H3.1-binding proteome, with emphasis on its interactions with histone chaperones and components of the replication fork. Quantitative mass spectrometry revealed 170 protein interactions, whereas a large-scale biochemical fractionation of H3...
November 19, 2015: Molecular Cell
Allison Haigney, M Daniel Ricketts, Ronen Marmorstein
The HAT-B enzyme complex is responsible for acetylating newly synthesized histone H4 on lysines K5 and K12. HAT-B is a multisubunit complex composed of the histone acetyltransferase 1 (Hat1) catalytic subunit and the Hat2 (rbap46) histone chaperone. Hat1 is predominantly localized in the nucleus as a member of a trimeric NuB4 complex containing Hat1, Hat2, and a histone H3-H4 specific histone chaperone called Hif1 (NASP). In addition to Hif1 and Hat2, Hat1 interacts with Asf1 (anti-silencing function 1), a histone chaperone that has been reported to be involved in both replication-dependent and -independent chromatin assembly...
December 18, 2015: Journal of Biological Chemistry
Chen Wang, Jian-Feng Chang, Hongli Yan, Da-Liang Wang, Yan Liu, Yuanya Jing, Meng Zhang, Yu-Long Men, Dongdong Lu, Xiao-Mei Yang, Su Chen, Fang-Lin Sun
Chromatin is a highly organized and dynamic structure in eukaryotic cells. The change of chromatin structure is essential in many cellular processes, such as gene transcription, DNA damage repair and others. Anti-silencing function 1 (ASF1) is a histone chaperone that participates in chromatin higher-order organization and is required for appropriate chromatin assembly. In this study, we identified the E2 ubiquitin-conjugating enzyme RAD6 as an evolutionary conserved interacting protein of ASF1 in D. melanogaster and H...
October 6, 2015: Oncotarget
Maheshi Udugama, Fiona T M Chang, F Lyn Chan, Michelle C Tang, Hilda A Pickett, James D R McGhie, Lynne Mayne, Philippe Collas, Jeffrey R Mann, Lee H Wong
In addition to being a hallmark at active genes, histone variant H3.3 is deposited by ATRX at repressive chromatin regions, including the telomeres. It is unclear how H3.3 promotes heterochromatin assembly. We show that H3.3 is targeted for K9 trimethylation to establish a heterochromatic state enriched in trimethylated H3.3K9 at telomeres. In H3f3a(-/-) and H3f3b(-/-) mouse embryonic stem cells (ESCs), H3.3 deficiency results in reduced levels of H3K9me3, H4K20me3 and ATRX at telomeres. The H3f3b(-/-) cells show increased levels of telomeric damage and sister chromatid exchange (t-SCE) activity when telomeres are compromised by treatment with a G-quadruplex (G4) DNA binding ligand or by ASF1 depletion...
December 2, 2015: Nucleic Acids Research
Christian Reiter, Franziska Heise, Ho-Ryun Chung, Ann E Ehrenhofer-Murray
The histone acetyltransferase Sas2 is part of the SAS-I complex and acetylates lysine 16 of histone H4 (H4 K16Ac) in the genome of Saccharomyces cerevisiae. Sas2-mediated H4 K16Ac is strongest over the coding region of genes with low expression. However, it is unclear how Sas2-mediated acetylation is incorporated into chromatin. Our previous work has shown physical interactions of SAS-I with the histone chaperones CAF-I and Asf1, suggesting a link between SAS-I-mediated acetylation and chromatin assembly. Here, we find that Sas2-dependent H4 K16Ac in bulk histones requires passage of the cells through the S-phase of the cell cycle, and the rate of increase in H4 K16Ac depends on both CAF-I and Asf1, whereas steady-state levels and genome-wide distribution of H4 K16Ac show only mild changes in their absence...
November 2015: FEMS Yeast Research
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