title: Regulation of replication licensing by acetyltransferase Hbo1.
abstract: The initiation of DNA replication is tightly regulated in eukaryotic cells to ensure that the genome is precisely duplicated once and only once per cell cycle. This is accomplished by controlling the assembly of a prereplicative complex (pre-RC) which involves the sequential binding to replication origins of the origin recognition complex (ORC), Cdc6/Cdc18, Cdt1, and the minichromosome maintenance complex (Mcm2-Mcm7, or Mcm2-7). Several mechanisms of pre-RC regulation are known, including ATP utilization, cyclin-dependent kinase levels, protein turnover, and Cdt1 binding by geminin. Histone acetylation may also affect the initiation of DNA replication, but at present neither the enzymes nor the steps involved are known. Here, we show that Hbo1, a member of the MYST histone acetyltransferase family, is a previously unrecognized positive regulatory factor for pre-RC assembly. When Hbo1 expression was inhibited in human cells, Mcm2-7 failed to associate with chromatin even though ORC and Cdc6 loading was normal. When Xenopus egg extracts were immunodepleted of Xenopus Hbo1 (XHbo1), chromatin binding of Mcm2-7 was lost, and DNA replication was abolished. The binding of Mcm2-7 to chromatin in XHbo1-depleted extracts could be restored by the addition of recombinant Cdt1.
authors.affiliation: Department of Microbiology, University of Virginia Health System, P.O. Box 800734, Charlottesville, VA 22908-0734, USA.
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Iizuka
authors.forename: Tomoko
authors.initials: T
authors.lastname: Matsui
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Takisawa
authors.forename: M Mitchell
authors.initials: MM
authors.lastname: Smith
mesh_terms: D000107:Acetylation; D000595:Amino Acid Sequence; D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism*; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000378:metabolism*; D016193:G1 Phase; D051548:Histone Acetyltransferases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D006801:Humans; D064111:Minichromosome Maintenance Complex Component 2; D064168:Minichromosome Maintenance Complex Component 7; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D014981:Xenopus; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: C406819:Cdt1 protein, Xenopus; D018797:Cell Cycle Proteins; D002843:Chromatin; D004268:DNA-Binding Proteins; D006657:Histones; D009687:Nuclear Proteins; D029867:Xenopus Proteins; D051548:Histone Acetyltransferases; C508030:KAT7 protein, Xenopus; C496553:KAT7 protein, human; C084859:MCM2 protein, human; C101624:MCM7 protein, human; D064111:Minichromosome Maintenance Complex Component 2; D064168:Minichromosome Maintenance Complex Component 7