Inducible repair of phosphotriesters in Escherichia coli.

Abstract

Extracts from E. coli cells induced for the adaptive response were prepared that are capable of repairing O6-methylguanine, O4-methylthymine and the phosphotriesters produced on the DNA backbone by alkylating agents such as N-methyl-N''-nitro-N-nitrosoguanidine (MNNG). The phosphotriesters are repaired by a methyltransferase distinct from the one that demethylates of O6-methylguanine. This increased capacity to repair phosphotriesters may account for much of the increased resistance to MNNG toxicity seen in cultures induced for the adaptive response.