title: Rad50 is not essential for the Mre11-dependent repair of DNA double-strand breaks in Halobacterium sp. strain NRC-1.
abstract: The genome of the halophilic archaeon Halobacterium sp. strain NRC-1 encodes homologs of the eukaryotic Mre11 and Rad50 proteins, which are involved in the recognition and end processing of DNA double-strand breaks in the homologous recombination repair pathway. We have analyzed the phenotype of Halobacterium deletion mutants lacking mre11 and/or rad50 after exposure to UV-C radiation, an alkylating agent (N-methyl-N'-nitro-N-nitrosoguanidine), and gamma radiation, none of which resulted in a decrease in survival of the mutant strains compared to that of the background strain. However, a decreased rate of repair of DNA double-strand breaks in strains lacking the mre11 gene was observed using pulsed-field gel electrophoresis. These observations led to the hypothesis that Mre11 is essential for the repair of DNA double-strand breaks in Halobacterium, whereas Rad50 is dispensable. This is the first identification of a Rad50-independent function for the Mre11 protein, and it represents a shift in the Archaea away from the eukaryotic model of homologous recombination repair of DNA double-strand breaks.
authors.affiliation: Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA. jdiruggiero@jhu.edu
authors.forename: A
authors.initials: A
authors.lastname: Kish
authors.forename: J
authors.initials: J
authors.lastname: DiRuggiero
mesh_terms: D000477:Alkylating Agents / Q000494:pharmacology; D019843:Archaeal Proteins / Q000235:genetics* / Q000378:metabolism*; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D019641:DNA, Archaeal / Q000737:chemistry; D016521:Electrophoresis, Gel, Pulsed-Field; D004706:Endodeoxyribonucleases / Q000235:genetics* / Q000378:metabolism*; D005090:Exodeoxyribonucleases / Q000235:genetics* / Q000378:metabolism*; D005720:Gamma Rays; D017353:Gene Deletion; D006217:Halobacterium / Q000187:drug effects / Q000201:enzymology / Q000502:physiology* / Q000528:radiation effects; D008769:Methylnitronitrosoguanidine / Q000493:pharmacokinetics; D050296:Microbial Viability; D014466:Ultraviolet Rays
chemical_list: D000477:Alkylating Agents; D019843:Archaeal Proteins; D019641:DNA, Archaeal; D008769:Methylnitronitrosoguanidine; D004706:Endodeoxyribonucleases; D005090:Exodeoxyribonucleases; C415985:Mre11 protein, archaeal; C415984:Rad50 protein, archaeal