title: A double-strand break repair component is essential for S phase completion in fission yeast cell cycling.
abstract: Fission yeast rad22(+), a homologue of budding yeast RAD52, encodes a double-strand break repair component, which is dispensable for proliferation. We, however, have recently obtained a cell division cycle mutant with a temperature-sensitive allele of rad22(+), designated rad22-H6, which resulted from a point mutation in the conserved coding sequence leading to one amino acid alteration. We have subsequently isolated rad22(+) and its novel homologue rti1(+) as multicopy suppressors of this mutant. rti1(+) suppresses all the defects of cells lacking rad22(+). Mating type switch-inactive heterothallic cells lacking either rad22(+) or rti1(+) are viable, but those lacking both genes are inviable and arrest proliferation with a cell division cycle phenotype. At the nonpermissive temperature, a synchronous culture of rad22-H6 cells performs DNA synthesis without delay and arrests with chromosomes seemingly intact and replication completed and with a high level of tyrosine-phosphorylated Cdc2. However, rad22-H6 cells show a typical S phase arrest phenotype if combined with the rad1-1 checkpoint mutation. rad22(+) genetically interacts with rad11(+), which encodes the large subunit of replication protein A. Deletion of rad22(+)/rti1(+) or the presence of rad22-H6 mutation decreases the restriction temperature of rad11-A1 cells by 4-6 degrees C and leads to cell cycle arrest with chromosomes incompletely replicated. Thus, in fission yeast a double-strand break repair component is required for a certain step of chromosome replication unlinked to repair, partly via interacting with replication protein A.
authors.affiliation: Department of Biochemistry and Molecular Biology, The University of Tokyo, Graduate School of Medicine, Tokyo 113-0033, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Suto
authors.forename: A
authors.initials: A
authors.lastname: Nagata
authors.forename: H
authors.initials: H
authors.lastname: Murakami
authors.forename: H
authors.initials: H
authors.lastname: Okayama
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001761:Bleomycin / Q000494:pharmacology; D002453:Cell Cycle / Q000235:genetics; D002455:Cell Division / Q000235:genetics; D003001:Cloning, Molecular; D004260:DNA Repair / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D049770:Genes, Mating Type, Fungal; D008969:Molecular Sequence Data; D009154:Mutation; D051716:Replication Protein A; D016196:S Phase / Q000235:genetics; D029702:Schizosaccharomyces pombe Proteins; D013489:Suppression, Genetic; D013696:Temperature; D015003:Yeasts / Q000235:genetics*
chemical_list: D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D051716:Replication Protein A; D029702:Schizosaccharomyces pombe Proteins; C085412:rad52 protein, S pombe; D001761:Bleomycin