Mutagenic potency of MMS‐induced 1meA/3meC lesions in E. coli (original) (raw)

2009, Environmental and …

The mutagenic activity of MMS in E. coli depends on the susceptibility of DNA bases to methylation and their repair by cellular defense systems. Among the lesions in methylated DNA is 1meA/ 3meC, which is recently recognized as being mutagenic. In this report, special attention is focused on the mutagenic properties of 1meA/3meC which, by the activity of AlkB-dioxygenase, are quickly and efficiently converted to natural A/C bases in the DNA of E. coli alkB 1 strains, preventing 1meA/ 3meC-induced mutations. We have found that in the absence of AlkB-mediated repair, MMS treatment results in an increased frequency of four types of base substitutions: GC?CG, GC?TA, AT?CG, and AT?TA, whereas overproduction of PolV in CC101-106 alkB 2 /pRW134 strains leads to a markedly elevated level of GC?TA, GC?CG, and AT?TA transversions. It has been observed V C 2009 Wiley-Liss, Inc.