DNA repair and oxidative stress defense systems in radiation-resistant .

is a bacterium isolated from hot springs in Portugal, and named after Dr. Robert G.E. Murray in recognition of his research on the genus . Like other species, is extremely resistant to ionizing radiation. Repair of massive DNA damage and limitation of oxidative protein damage are two important factors contributing to the robustness of bacteria. Here, we identify, among others, the DNA repair and oxidative stress defense proteins in , and highlight special features of . For DNA repair, does not contain a standalone uracil-DNA glycosylase (Ung), but it encodes a protein in which Ung is fused to a DNA photolyase domain (PhrB). UvrB and UvrD contain large insertions corresponding to inteins. One of its endonuclease III enzymes lacks a [4Fe-4S] cluster. possesses a homolog of the error-prone DNA polymerase IV. Concerning oxidative stress defense, encodes a manganese catalase in addition to a heme catalase. Its organic hydroperoxide resistance protein Ohr is atypical because the redox active cysteines are present in a CXXC motif. These and other characteristics of show further diversity among bacteria with respect to resistance-associated mechanisms.