The Schizosaccharomyces pombe rad60 gene is essential for repairing double-strand DNA breaks spontaneously occurring during replication and induced by DNA-damaging agents.
To identify novel genes involved in DNA double-strand break (DSB) repair, we previously isolated Schizosaccharomyces pombe mutants which are hypersensitive to methyl methanesulfonate (MMS) and synthetic lethals with rad2. This study characterizes one of these mutants, rad60-1. The gene that complements the MMS sensitivity of this mutant was cloned and designated rad60. rad60 encodes a protein with 406 amino acids which has the conserved ubiquitin-2 motif found in ubiquitin family proteins. rad60-1 is hypersensitive to UV and gamma rays, epistatic to rhp51, and defective in the repair of DSBs caused by gamma-irradiation. The rad60-1 mutant is also temperature sensitive for growth. At the restrictive temperature (37 degrees C), rad60-1 cells grow for several divisions and then arrest with 2C DNA content; the arrested cells accumulate DSBs and have a diffuse and often aberrantly shaped nuclear chromosomal domain. The rad60-1 mutant is a synthetic lethal with rad18-X, and expression of wild-type rad60 from a multicopy plasmid partially suppresses the MMS sensitivity of rad18-X cells. rad18 encodes a conserved protein of the structural maintenance of chromosomes (SMC) family (A. R. Lehmann, M. Walicka, D. J. Griffiths, J. M. Murray, F. Z. Watts, S. McCready, and A. M. Carr, Mol. Cell. Biol. 15:7067-7080, 1995). These results suggest that S. pombe Rad60 is required to repair DSBs, which accumulate during replication, by recombination between sister chromatids. Rad60 may perform this function in concert with the SMC protein Rad18.
Morishita
Takashi
T
Department of Molecular Microbiology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan.
Tsutsui
Yasuhiro
Y
Iwasaki
Hiroshi
H
Shinagawa
Hideo
H
D000595:Amino Acid Sequence; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D004247:DNA / Q000378:metabolism / Q000528:radiation effects*; D004249:DNA Damage; D004260:DNA Repair / Q000235:genetics*; D004261:DNA Replication / Q000235:genetics*; D005720:Gamma Rays; D005800:Genes, Fungal / Q000235:genetics*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012568:Schizosaccharomyces / Q000235:genetics* / Q000502:physiology; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D013696:Temperature
D002868:Chromosomal Proteins, Non-Histone; D009687:Nuclear Proteins; C455501:Rad60 protein, S pombe; D011993:Recombinant Fusion Proteins; D029702:Schizosaccharomyces pombe Proteins; D004247:DNA