Identification and characterization of uvrA, a DNA repair gene of Deinococcus radiodurans

Deinococcus radiodurans is extraordinarily resistant to DNA damage, because of its unusually efficient DNA repair processes. The mtcA(+) and mtcB(+) genes of D. radiodurans, both implicated in excision repair, have been cloned and sequenced, showing that they are a single gene, highly homologous to the uvrA(+) genes of other bacteria. The Escherichia coli uvrA(+) gene was expressed in mtcA and mtcB strains, and it produced a high degree of complementation of the repair defect in these strains, suggesting that the UvrA protein of D. radiodurans is necessary but not sufficient to produce extreme DNA damage resistance. Upstream of the uvrA(+) gene are tao large open reading frames, both of which are directionally divergent from the uvrA(+) gene. Evidence is presented that the proximal of these open reading frames may be irrB(+).