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Title
Japanese: 
English:Competition between the Rad50 complex and the Ku heterodimer reveals a role for exo1 in processing double-strand breaks but not telomeres 
Author
Japanese: Tomita, K., Matsuura, A., Caspari, T., Carr, A.M., Akamatsu, Y., 岩崎博史, Mizuno, K.-I., Ohta, K., Uritani, M., Ushimaru, T., Yoshinaga, K., Ueno, M..  
English: Tomita, K., Matsuura, A., Caspari, T., Carr, A.M., Akamatsu, Y., Hiroshi Iwasaki, Mizuno, K.-I., Ohta, K., Uritani, M., Ushimaru, T., Yoshinaga, K., Ueno, M..  
Language English 
Journal/Book name
Japanese:Molecular and Cellular Biology 
English:Molecular and Cellular Biology 
Volume, Number, Page Vol. 23    No. 15    pp. 5186-5197
Published date Aug. 2003 
Publisher
Japanese: 
English: 
Conference name
Japanese: 
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Conference site
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Official URL http://www.scopus.com/inward/record.url?eid=2-s2.0-0042991423&partnerID=MN8TOARS
 
DOI https://doi.org/10.1128/MCB.23.15.5186-5197.2003
Abstract The Mre11-Rad50-Nbs1(Xrs2) complex and the Ku70-Ku80 heterodimer are thought to compete with each other for binding to DNA ends. To investigate the mechanism underlying this competition, we analyzed both DNA damage sensitivity and telomere overhangs in Schizosaccharomyces pombe rad50-d, rad50-d pku70-d, rad50-d exo1-d, and pku70-d rad50-d exo1-d cells. We found that rad50 exo1 double mutants are more methyl methanesulfonate (MMS) sensitive than the respective single mutants. The MMS sensitivity of rad50-d cells was suppressed by concomitant deletion of pku70+. However, the MMS sensitivity of the rad50 exo1 double mutant was not suppressed by the deletion of pku70+. The G-rich overhang at telomere ends in taz1-d cells disappeared upon deletion of rad50+, but the overhang reappeared following concomitant deletion of pku70+. Our data suggest that the Rad50 complex can process DSB ends and telomere ends in the presence of the Ku heterodimer. However, the Ku heterodimer inhibits processing of DSB ends and telomere ends by alternative nucleases in the absence of the Rad50-Rad32 protein complex. While we have identified Exo1 as the alternative nuclease targeting DNA break sites, the identity of the nuclease acting on the telomere ends remains elusive.

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