Overlapping functions of the Saccharomyces cerevisiae Mre11, Exo1 and Rad27 nucleases in DNA metabolism.

摘要: MRE11 functions in several aspects of DNA metabolism, including meiotic recombination, double-strand break repair, and telomere maintenance. Although the purified protein exhibits 3′ to 5′ exonuclease endonuclease activities vitro , Mre11 is implicated resection duplex ends vivo . The mre11-H125N mutation, which eliminates nuclease Mre11, causes an accumulation unprocessed breaks (DSBs) meiosis, but no defect processing HO-induced DSBs mitotic cells, suggesting existence redundant activities. Mutation EXO1 encodes a exonuclease, was found increase ionizing radiation sensitivity both mre11 Δ strains, exo1 strain showed normal kinetics mating-type switching more resistant than strain. This suggests that other nucleases can compensate for loss Exo1 nucleases, not Mre11-Rad50-Xrs2 complex. Deletion RAD27 flap endonuclease, inviability strains. When combined with leaky rad27-6 double mutants were viable γ-ray sensitive mutant unlikely be due defective DSB processing.