Inducible repair of near-UV radiation lethal damage in E. coli.

We present here the initial characterization of a new repair system which is induced in actively growing cultures of Escherichia coli and which repairs a major fraction of lethal damage produced by near-UV (310-400 nm) light. This system is different from the error-prone 'SOS' repair system for DNA, known to be induced in E. coli by treatments which damage DNA and/or inhibit DNA replication, such as irradiation by far-UV (254 nm) light or X rays, thymine starvation or treatment with naladixic acid or mitomycin C. The SOS response requires induction of an 'X' protein, the product of the recA gene, whereas the inducible repair system described here utilizes proteins distinct from the X protein.