The role of umuC gene product in mutagenesis by simple alkylating agents.

This paper describes studies to determine the role of the umuC gene product in the process of alkylation induced mutagenesis. An active umuC gene is necessary for most MMS induced mutagenesis but it is not essential for EMS nor for MNNG induced mutagenesis in either normal or adapted cultures. In this respect the umuC mutation differs from lexA mutations which have a striking effect on MNNG induced mutagenesis (Schendel, et al., 1978). These findings have prompted a re-evaluation of these previously published data and the advancement of an hypothesis which explains the lexA effect without evoking a role for error-prone repair in the process of alkylation induced mutagenesis. It was also observed that exposure to MNNG is capable of generating a small amount of W-reactivation and W-mutagenesis capacity in a umuC strain which is totally blocked for UV induced reactivation. In light of this result a possible function for the umuC gene product is discussed.