mutM, a second mutator locus in Escherichia coli that generates G.C----T.A transversions

Abstract
We used strains carrying specific lacZ alleles to identify a new mutator locus in Escherichia coli which generates only G.C----T.A transversions among base substitutions. The locus, mutM, mapped near the cysE locus, which is at 81 min on the genetic map.