Escherichia coli gene that controls sensitivity to alkylating agents

Abstract
A new type of E. coli mutant which shows increased sensitivity to methyl methane sulfonate but not to UV light or to .gamma. rays was isolated after mutagenesis with N-methyl-N''-nitro-N-nitrosoguanidine. The mutant is unable to reactivate phage .lambda.vir or double-stranded .vphi.X174 DNA (replicative form) that was treated with methyl methane sulfonate. The mutant is also sensitive to other alkylating agents, such as ethyl methane sulfonate, mitomycin C and N-methyl-N''-nitro-N-nitrosoguanidine. It grows normally and exhibits almost normal recombination proficiency. The mutant possesses normal levels of DNA polymerase I, exonuclease I, exonuclease V, endonuclease specific for methyl methane sulfonate-treated DNA and 3-methyladenine-DNA glycosidase activities. The genetic locus responsible was named alk and is located near his on the chromosome.