Down-regulation of radioresitance by LexA2 in

Sato, Katsuya; Oba, Hirofumi; Sghaier, H.*; Narumi, Issei

In an effort to gain an insight into the role of LexA2 of in the radiation response mechanism, gene disruptant strains were generated and investigated. The intracellular level of RecA increased in and disruptant strains following irradiation as in the wild-type strain. These results indicated that the two LexA homologs did not possess functional overlap regarding the induction of RecA. The disruptant strains exhibited a much higher resistance to rays than the wild-type strain. Furthermore, a luciferase assay showed that promoter activation was enhanced in the disruptant strain following irradiation. The gene encoding the novel radiation-inducible protein PprA plays a critical role in the radioresistance of . The increase in radioresistance of the disruptant strain is explained in part by the enhancement of promoter activation.