Molecular characterization of the role of the Schizosaccharomyces pombe nip1+/ctp1+ gene in DNA double-strand break repair in association with the Mre11-Rad50-Nbs1 complex.
The Schizosaccharomyces pombe nip1(+)/ctp1(+) gene was previously identified as an slr (synthetically lethal with rad2) mutant. Epistasis analysis indicated that Nip1/Ctp1 functions in Rhp51-dependent recombinational repair, together with the Rad32 (spMre11)-Rad50-Nbs1 complex, which plays important roles in the early steps of DNA double-strand break repair. Nip1/Ctp1 was phosphorylated in asynchronous, exponentially growing cells and further phosphorylated in response to bleomycin treatment. Overproduction of Nip1/Ctp1 suppressed the DNA repair defect of an nbs1-s10 mutant, which carries a mutation in the FHA phosphopeptide-binding domain of Nbs1, but not of an nbs1 null mutant. Meiotic DNA double-strand breaks accumulated in the nip1/ctp1 mutant. The DNA repair phenotypes and epistasis relationships of nip1/ctp1 are very similar to those of the Saccharomyces cerevisiae sae2/com1 mutant, suggesting that Nip1/Ctp1 is a functional homologue of Sae2/Com1, although the sequence similarity between the proteins is limited to the C-terminal region containing the RHR motif. We found that the RxxL and CxxC motifs are conserved in Schizosaccharomyces species and in vertebrate CtIP, originally identified as a cofactor of the transcriptional corepressor CtBP. However, these two motifs are not found in other fungi, including Saccharomyces and Aspergillus species. We propose that Nip1/Ctp1 is a functional counterpart of Sae2/Com1 and CtIP.
Akamatsu
Yufuko
Y
Division of Molecular and Cellular Biology, International Graduate School of Arts and Sciences, Yokohama City University, Suehiro-cho, Tsurumi, Yokohama, Kanagawa 230-0045, Japan.
Murayama
Yasuto
Y
Yamada
Takatomi
T
Nakazaki
Tomofumi
T
Tsutsui
Yasuhiro
Y
Ohta
Kunihiro
K
Iwasaki
Hiroshi
H
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D017124:Conserved Sequence; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004843:Epistasis, Genetic; D005090:Exodeoxyribonucleases; D008540:Meiosis / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D017434:Protein Structure, Tertiary / Q000235:genetics; D051135:Rad51 Recombinase / Q000235:genetics / Q000378:metabolism; D012568:Schizosaccharomyces / Q000235:genetics* / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*
D002868:Chromosomal Proteins, Non-Histone; C525888:Ctp1 protein, S pombe; D004268:DNA-Binding Proteins; C478035:Nbs1 protein, S pombe; C084232:RHP51 protein, S pombe; C480032:Rad50 protein, S pombe; D029702:Schizosaccharomyces pombe Proteins; D051135:Rad51 Recombinase; D005090:Exodeoxyribonucleases; C092453:Mre11 protein, S pombe