Inducible, error-free DNA Repair in tsl recA mutants of E. coli.

Host of cell reactivation and UV reactivation and mutagenesis of UV-irradiated phage mu were measured in tsl recAplus and tsl recA host mutants. Host cell reactivation was slightly more efficient in the tsl recA strain. Phage was UV-reactivated in the tsl recA strain with about one-half the efficiency of that in the wild type strain, but there was no corresponding mutagenesis of phage. UV-reactivation was also slightly lower and mutagenesis several-fold lower than normal in the tsl recAplus strain. To account for these observations, we propose that there is an inducible, error-free pathway of DNA repair in E. coli that competes with error-prone repair for repair of phage lesions.