Competition between the Rad50 Complex and the Ku Heterodimer Reveals a Role for Exo1 in Processing Double-Strand Breaks but Not Telomeres

• DOI: 10.1128/mcb.23.15.5186-5197.2003
• Publication Date: 2003-07-14T18:50:19Z
• Authors: Kazunori Tomita; Akira Matsuura; Thomas Caspari; Antony M. Carr; Yufuko Akamatsu; Hiroshi Iwasaki; Ken-ichi Mizuno; Kunihiro Ohta; Masahiro Uritani; Takashi Ushimaru; Koichi Yoshinaga; Masaru Ueno
• Keywords: Rad50; Ku70; Nuclease; Telomere-binding protein

The Mre11-Rad50-Nbs1(Xrs2) complex and the Ku70-Ku80 heterodimer are thought to compete with each other for binding DNA ends. To investigate mechanism underlying this competition, we analyzed both damage sensitivity telomere overhangs in Schizosaccharomyces pombe rad50-d, rad50-d pku70-d, exo1-d, pku70-d exo1-d cells. We found that rad50 exo1 double mutants more methyl methanesulfonate (MMS) sensitive than respective single mutants. MMS of cells was suppressed by concomitant deletion pku70+ . However, mutant not G-rich overhang at ends taz1-d disappeared upon rad50+ , but reappeared following Our data suggest Rad50 can process DSB presence Ku heterodimer. inhibits processing alternative nucleases absence Rad50-Rad32 protein complex. While have identified Exo1 as nuclease targeting break sites, identity acting on remains elusive.