TY - JOUR T1 - Mre11-Rad50 Promotes Rapid Repair of DNA Damage in the Polyploid Archaeon Haloferax volcanii by Restraining Homologous Recombination A1 - Delmas, Stéphane A1 - Shunburne, Lee A1 - Ngo, Hien-Ping A1 - Allers, Thorsten Y1 - 2009/07/10 N2 - Author Summary Most organisms contain only one or two copies of their genome, but in some species multiple copies are found. The presence of multiple genome copies (polyploidy) has profound implications for DNA repair and is frequently seen in cancer cells. We have studied DNA repair in the archaeon Haloferax volcanii, which contains up to 20 genome copies. Archaea are a third form of life distinct from bacteria and eukaryotes. We have focused on the DNA repair proteins Mre11 and Rad50, which are found in virtually all organisms and which in humans act to prevent cancer. Surprisingly, we have found that H. volcanii cells deficient in Mre11-Rad50 are more resistant to DNA damage than wild-type cells. The DNA damage resistance of mre11 rad50 mutant cells appears to be due to the exclusive use of homologous recombination, a DNA repair mechanism that is accurate but has the potential to generate genome rearrangements that require time to resolve. Correspondingly, we have found repair of DNA damage in mre11 rad50 mutants takes longer than in wild-type cells. Our results suggest that polyploid organisms employ a program of DNA repair that minimizes their reliance on homologous recombination. JF - PLOS Genetics JA - PLOS Genetics VL - 5 IS - 7 UR - https://doi.org/10.1371/journal.pgen.1000552 SP - e1000552 EP - PB - Public Library of Science M3 - doi:10.1371/journal.pgen.1000552 ER -