title: Abundance of prereplicative complexes (Pre-RCs) facilitates recombinational repair under replication stress in fission yeast.
abstract: Mcm2-7 complexes are loaded onto chromatin with the aid of Cdt1 and Cdc18/Cdc6 and form prereplicative complexes (pre-RCs) at multiple sites on each chromosome. Pre-RCs are essential for DNA replication and surviving replication stress. However, the mechanism by which pre-RCs contribute to surviving replication stress is largely unknown. Here, we isolated the fission yeast mcm6-S1 mutant that was hypersensitive to methyl methanesulfonate (MMS) and camptothecin (CPT), both of which cause forks to collapse. The mcm6-S1 mutation impaired the interaction with Cdt1 and decreased the binding of minichromosome maintenance (MCM) proteins to replication origins. Overexpression of Cdt1 restored MCM binding and suppressed the sensitivity to MMS and CPT, suggesting that the Cdt1-Mcm6 interaction is important for the assembly of pre-RCs and the repair of collapsed forks. MMS-induced Chk1 phosphorylation and Rad22/Rad52 focus formation occurred normally, whereas cells containing Rhp54/Rad54 foci, which are involved in DNA strand exchange and dissociation of the joint molecules, were increased. Remarkably, G(1) phase extension through deletion of an S phase cyclin, Cig2, as well as Cdt1 overexpression restored pre-RC assembly and suppressed Rhp54 accumulation. A cdc18 mutation also caused hypersensitivity to MMS and CPT and accumulation of Rhp54 foci. These data suggest that an abundance of pre-RCs facilitates a late step in the recombinational repair of collapsed forks in the following S phase.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan; Graduate School of Frontier Biosciences, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Maki
authors.affiliation: Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Inoue
authors.affiliation: Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Onaka
authors.affiliation: Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Hashizume
authors.affiliation: Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Somete
authors.affiliation: Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kobayashi
authors.affiliation: Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan; Graduate School of Frontier Biosciences, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Shigefumi
authors.initials: S
authors.lastname: Murakami
authors.affiliation: Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Chikako
authors.initials: C
authors.lastname: Shigaki
authors.affiliation: Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Tatsuro S
authors.initials: TS
authors.lastname: Takahashi
authors.affiliation: Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan; Graduate School of Frontier Biosciences, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Hisao
authors.initials: H
authors.lastname: Masukata
authors.affiliation: Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan. Electronic address: takuro4@bio.sci.osaka-u.ac.jp.
authors.forename: Takuro
authors.initials: T
authors.lastname: Nakagawa
mesh_terms: D004271:DNA, Fungal / Q000096:biosynthesis* / Q000235:genetics; D016193:G1 Phase / Q000502:physiology*; D015966:Gene Expression Regulation, Fungal / Q000502:physiology; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010766:Phosphorylation; D016196:S Phase / Q000502:physiology*; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D004271:DNA, Fungal; D046912:Multiprotein Complexes; D029702:Schizosaccharomyces pombe Proteins