[The effect of am umuC mutation on the induction of an SOS response in E. coli cella under the action of UV and gamma irradiation].

The kinetics of the SOS induction in E. coli cells of wild type and deficient in umuC gene exposed to UV and gamma-rays were analysed. In the presence of UmuC protein SOS induction was 3-5.5 times lower and delayed for about 30 minutes after both UV and gamma rays. It was shown that decrease of the SOS induction in wild type cells irradiated by UV was due to more effective elimination of the photolesions from DNA by excision repair system. UmuCD-dependent inhibition of DNA replication was discussed as a possible mechanism allowing additional time for error-free repair.