Replication-independent histone deposition by the HIR complex and Asf1.
The orderly deposition of histones onto DNA is mediated by conserved assembly complexes, including chromatin assembly factor-1 (CAF-1) and the Hir proteins . CAF-1 and the Hir proteins operate in distinct but functionally overlapping histone deposition pathways in vivo . The Hir proteins and CAF-1 share a common partner, the highly conserved histone H3/H4 binding protein Asf1, which binds the middle subunit of CAF-1 as well as to Hir proteins . Asf1 binds to newly synthesized histones H3/H4 , and this complex stimulates histone deposition by CAF-1 . In yeast, Asf1 is required for the contribution of the Hir proteins to gene silencing . Here, we demonstrate that Hir1, Hir2, Hir3, and Hpc2 comprise the HIR complex, which copurifies with the histone deposition protein Asf1. Together, the HIR complex and Asf1 deposit histones onto DNA in a replication-independent manner. Histone deposition by the HIR complex and Asf1 is impaired by a mutation in Asf1 that inhibits HIR binding. These data indicate that the HIR complex and Asf1 proteins function together as a conserved eukaryotic pathway for histone replacement throughout the cell cycle.
Green
Erin M
EM
Lawrence Berkeley National Laboratory and Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720, USA.
Antczak
Andrew J
AJ
Bailey
Aaron O
AO
Franco
Alexa A
AA
Wu
Kevin J
KJ
Yates
John R
JR
Kaufman
Paul D
PD
D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D056504:Chromatin Assembly Factor-1; D047369:Chromatin Immunoprecipitation; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D004247:DNA / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D006657:Histones / Q000378:metabolism*; D015151:Immunoblotting; D013058:Mass Spectrometry; D018832:Molecular Chaperones; D046912:Multiprotein Complexes / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D015003:Yeasts
C109731:ASF1 protein, S cerevisiae; D018797:Cell Cycle Proteins; D056504:Chromatin Assembly Factor-1; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; C078808:HIR1 protein, S cerevisiae; D006657:Histones; D018832:Molecular Chaperones; D046912:Multiprotein Complexes; D009687:Nuclear Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D004247:DNA