title: Isolation and characterization of the Schizosaccharomyces pombe rhp9 gene: a gene required for the DNA damage checkpoint but not the replication checkpoint.
abstract: Checkpoint controls exist in eukaryotic cells to ensure that cells do not enter mitosis in the presence of DNA damage or unreplicated chromosomes. In Schizosaccharomyces pombe many of the checkpoint genes analysed to date are required for both the DNA damage and the replication checkpoints, an exception being chk1 . We report here on the characterization of nine new methylmethane sulphonate (MMS)-sensitive S.pombe mutants, one of which is defective in the DNA damage checkpoint but not the replication checkpoint. We have cloned and sequenced the corresponding gene. The predicted protein is most similar to the Saccharomyces cerevisiae Rad9 protein, having 46% similarity and 26% identity. The S.pombe protein, which we have named Rhp9 (Rad9 homologue in S. pombe) on the basis of structural and phenotypic similarity, also contains motifs present in BRCA1 and 53BP1. Deletion of the gene is not lethal and results in a DNA damage checkpoint defect. Epistasis analysis with other S.pombe checkpoint mutants indicates that rhp9 acts in a process involving the checkpoint rad genes and that the rhp9 mutant is phenotypically very similar to chk1.
authors.affiliation: Department of Biochemistry, School of Biological Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK.
authors.forename: J
authors.initials: J
authors.lastname: Willson
authors.forename: S
authors.initials: S
authors.lastname: Wilson
authors.forename: N
authors.initials: N
authors.lastname: Warr
authors.forename: F Z
authors.initials: FZ
authors.lastname: Watts
mesh_terms: D000595:Amino Acid Sequence; D000970:Antineoplastic Agents / Q000494:pharmacology; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology; D001483:Base Sequence; D018797:Cell Cycle Proteins; D004249:DNA Damage / Q000187:drug effects / Q000235:genetics*; D004261:DNA Replication / Q000187:drug effects / Q000235:genetics*; D004271:DNA, Fungal / Q000096:biosynthesis*; D004843:Epistasis, Genetic; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D017353:Gene Deletion; D006918:Hydroxyurea / Q000494:pharmacology; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins; D010641:Phenotype; D010957:Plasmids / Q000378:metabolism; D011836:Radiation Tolerance; D015183:Restriction Mapping; D012568:Schizosaccharomyces / Q000187:drug effects / Q000235:genetics*; D029702:Schizosaccharomyces pombe Proteins
chemical_list: D000970:Antineoplastic Agents; D018906:Antineoplastic Agents, Alkylating; D018797:Cell Cycle Proteins; C109867:Crb2 protein, S pombe; D004271:DNA, Fungal; D005656:Fungal Proteins; D009687:Nuclear Proteins; D029702:Schizosaccharomyces pombe Proteins; C069930:rad9 protein; D008741:Methyl Methanesulfonate; D006918:Hydroxyurea