Evaluation of the factor of E. coli growth inhibition by recombinant DNA methyltransferase, and a new tip for the transformation of DNA methyltransferases into E. coli.

Studies on DNA methyltransferases (MTases) have described growth inhibition in transformed MTase-Escherichia coli. In addition, this phenomenon has been reported to negatively impact on the transformation efficiency of E. coli. In this study, we identified the cause of the growth inhibition of MTase-transformed E. coli by DNA MTase. We also described that metal ions promote the efficiency of the transformation of DNA MTases into E. coli. Growth inhibition was evaluated through spot plating, which revealed growth inhibition in M.ApeKI, which is the thermostability DNA (cytosine-5)-methyltransferase, and the mutant (possessing only DNA-binding ability). We previously showed that Cu and Zn inhibited the catalytic activity and DNA binding ability of M.ApeKI in vitro. Therefore, we examined the cancellation of the growth inhibition of the host cell and the construction of M.ApeKI in the presence of these metal ions. We also indicated that this method could be adapted to other DNA MTases.