RECO AND RECR MUTATIONS DELAY INDUCTION OF THE SOS RESPONSE IN ESCHERICHIA-COLI

RecF, RecO and RecR, three of the important proteins of the RecF pathw ay of recombination, are also needed for repair of DNA damage due to U V irradiation. recF mutants are not proficient in cleaving LexA repres sor in vivo following DNA damage; therefore they show a delay of induc tion of the SOS response. In this communication, by measuring the in v ivo levels of LexA repressor using anti-LexA antibodies, we show the r ecO and recR mutant strains are also not proficient in LexA cleavage r eactions. In addition, we show that recO and recR mutations delay indu ction of beta-galactosidase activity expressed from a lexA-regulated p romoter following exposure of cells to UV, thus further supporting the idea that recF, recO, and recR gene products are needed for induction of the SOS response.