Molecular mutagenesis induced by glycidyl methacrylate

Glycidyl methacrylate (GMA) is a recently recognized mutagen. In order to explore the mutagenicity and mechanism of GMA, plasmid pBR322 was used for in vitro binding, mutant screening, restriction enzyme mapping, and DNA sequencing. To explore the mechanism by which an initial premutational event is converted into a stable heritable mutation, pBR322 and GMA-bound pBR322 were transformed into E. coli HB101, and the following results were obtained: 1) GMA-bound pBR322 induced phenotype changes in competent cells. Two stable and heritable mutants were isolated (ApRTcS and ApSTcR). 2) When restriction enzyme mapping was used to analyze the mutant ApRTcS, four of seven maps showed changes, but no large DNA insertion or deletion were observed. 3) The frequency of deletion and insertion forms counted about 10%. Sequence specificity and hot spot regions were evident in the sequence analysis of mutated plasmid. The above results indicate that the premutagenic lesions of plasmid induced by GMA can be converted into point mutations in vivo.