Molecular characterization of the Schizosaccharomyces pombe nbs1+ gene involved in DNA repair and telomere maintenance.
The human MRN complex is a multisubunit nuclease that is composed of Mre11, Rad50, and Nbs1 and is involved in homologous recombination and DNA damage checkpoints. Mutations of the MRN genes cause genetic disorders such as Nijmegen breakage syndrome. Here we identified a Schizosaccharomyces pombe nbs1(+) homologue by screening for mutants with mutations that caused methyl methanesulfonate (MMS) sensitivity and were synthetically lethal with the rad2Delta mutation. Nbs1 physically interacts with the C-terminal half of Rad32, the Schizosaccharomyces pombe Mre11 homologue, in a yeast two-hybrid assay. nbs1 mutants showed sensitivities to gamma-rays, UV, MMS, and hydroxyurea and displayed telomere shortening similar to the characteristics of rad32 and rad50 mutants. nbs1, rad32, and rad50 mutant cells were elongated and exhibited abnormal nuclear morphology. These findings indicate that S. pombe Nbs1 forms a complex with Rad32-Rad50 and is required for homologous recombination repair, telomere length regulation, and the maintenance of chromatin structure. Amino acid sequence features and some characteristics of the DNA repair function suggest that the S. pombe Rad32-Rad50-Nbs1 complex has functional similarity to the corresponding MRN complexes of higher eukaryotes. Therefore, S. pombe Nbs1 will provide an additional model system for studying the molecular function of the MRN complex associated with genetic diseases.
Ueno
Masaru
M
Department of Chemistry, Faculty of Science, Shizuoka University, 836 Oya, Shizuoka 422-8529, Japan. scmueno@ipc.shizuoka.ac.jp
Nakazaki
Tomofumi
T
Akamatsu
Yufuko
Y
Watanabe
Kikuo
K
Tomita
Kazunori
K
Lindsay
Howard D
HD
Shinagawa
Hideo
H
Iwasaki
Hiroshi
H
D000595:Amino Acid Sequence; D001665:Binding Sites; D018797:Cell Cycle Proteins / Q000235:genetics; D002467:Cell Nucleus / Q000502:physiology; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics* / Q000378:metabolism*; D004260:DNA Repair / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004706:Endodeoxyribonucleases / Q000378:metabolism; D005090:Exodeoxyribonucleases / Q000378:metabolism; D006918:Hydroxyurea / Q000494:pharmacology; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D012568:Schizosaccharomyces / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics* / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D016615:Telomere / Q000502:physiology*; D020798:Two-Hybrid System Techniques; D014466:Ultraviolet Rays
D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; C112156:NBN protein, human; C478035:Nbs1 protein, S pombe; D009687:Nuclear Proteins; C086930:RAD50 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; C086929:XRS2 protein, S cerevisiae; D008741:Methyl Methanesulfonate; D004706:Endodeoxyribonucleases; D005090:Exodeoxyribonucleases; C094191:MRE11 protein, S cerevisiae; C092453:Mre11 protein, S pombe; D006918:Hydroxyurea