Identification and Characterization of uvrA, a DNA Repair Gene of Deinococcus radiodurans

Gram positive bacteria of the genus Deinococcus possess extraordinary resistance to the lethal and mutagenic effects of most agents that damage DNA, including ultraviolet UV radiation and the genotoxin mitomycin C MMC. The extremely efficient ability to repair DNA damage induced by UV and MMC has been attributed, through complementation analysis, to two putative novel repair endonucleases UV endonuclease-a and UV endonuc1ease-p that incise deinococcal chromosomal DNA at or near sites of DNA damage, thereby initiating enzymatic excision of the DNA lesions. These repair endonucleases are encoded by the mtcA, mtcB endonucleasel and uvsC, uvsD, and uvsE endonuclease-beta genes. The gene encoded by mtcA and mtcB was found by DNA sequence analysis to be a single gene encoding a protein identified as the homolog of E. coli UvrA. UvrA is one protein of the UvrABC exonuclease complex in E. coli that recognizes thymine dimers and other bulky damage on nucleotide strands after UV induced DNA damage or other bulky DNA damage, such as MMC adducts. The nucleotide sequence of the uvrA homolog in D. radiodurans is over 60 homologous with E. coli and M. luteus uvrA nucleotide.