Acetylation of lysine 56 of histone H3 catalyzed by RTT109 and regulated by ASF1 is required for replisome integrity.
In budding yeast, acetylation of histone H3 lysine 56 (H3-K56) is catalyzed by the Rtt109-Vps75 histone acetyltransferase (HAT) complex, with Rtt109 being the catalytic subunit, and histone chaperone Asf1 is required for this modification. Cells lacking Rtt109 are susceptible to perturbations in DNA replication. However, how Asf1 regulates acetylation of H3-K56 and how loss of H3-K56 acetylation affects DNA replication are unclear. We show that at low concentrations the Rtt109-Vps75 HAT complex acetylates H3-K56 in vitro when H3/H4 is complexed with Asf1, but not H3/H4 tetramers, recapitulating the in vivo requirement of Asf1 for H3-K56 acetylation using recombinant proteins. Moreover, the Rtt109-Vps75 complex interacts with Asf1-H3/H4 but not Asf1. In vivo, the Rtt109-Asf1 interaction is also dependent on the ability of Asf1 to bind H3/H4. Furthermore, the Rtt109 homolog in Schizosaccharomyces pombe (SpRtt109) also displayed an Asf1-dependent H3-K56 HAT activity in vitro. These results indicate that Asf1 regulates H3-K56 acetylation by presenting histones H3 and H4 to Rtt109-Vps575 for acetylation, and this mechanism is likely to be conserved. Finally, we have shown that cells lacking Rtt109 or expressing H3-K56 mutants exhibited significant reduction in the association of three proteins with stalled DNA replication forks and hyper-recombination of replication forks stalled at replication fork barriers of the ribosomal DNA locus compared with wild-type cells. Taken together, these studies provide novel insight into the role of Asf1 in the regulation of H3-K56 acetylation and the function of this modification in DNA replication.
Han
Junhong
J
Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905.
Zhou
Hui
H
Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905.
Li
Zhizhong
Z
Structural Biology Program, Helen L. and Martin S. Kimmel Center for Biology and Medicine, Skirball Institute of Biomedicine and Department of Pharmacology, New York University School of Medicine, New York, New York 10016.
Xu
Rui-Ming
RM
Structural Biology Program, Helen L. and Martin S. Kimmel Center for Biology and Medicine, Skirball Institute of Biomedicine and Department of Pharmacology, New York University School of Medicine, New York, New York 10016.
Zhang
Zhiguo
Z
Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905. Electronic address: Zhang.Zhiguo@mayo.edu.
D000107:Acetylation; D004261:DNA Replication / Q000502:physiology*; D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism*; D004275:DNA, Ribosomal / Q000235:genetics / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism*; D051548:Histone Acetyltransferases / Q000235:genetics / Q000378:metabolism*; D006657:Histones / Q000378:metabolism*; D008239:Lysine / Q000235:genetics / Q000378:metabolism; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D040641:Quantitative Trait Loci / Q000502:physiology; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D000099272:Replisomes
D004271:DNA, Fungal; D004275:DNA, Ribosomal; D004259:DNA-Directed DNA Polymerase; D051548:Histone Acetyltransferases; D006657:Histones; D008239:Lysine; D018832:Molecular Chaperones; D009097:Multienzyme Complexes; D029702:Schizosaccharomyces pombe Proteins; D000099272:Replisomes; C524040:Cia1 protein, S pombe; C524041:Rtt109 protein, S pombe