Abstract
The cytosine methyltransferases (MTases) M. HhaIand M. HpaII bind substrates in which the target cytosine is replaced by uracil or thymine, i.e. DNA containing a U:G or a T:G mismatch. We have extended this observation to the EcoRII MTase (M. EcoRII) and determined the apparent Kd for binding. Using a genetic assay we have also tested the possibility that MTase binding to U:G mismatches may interfere with repair of the mismatches and promote C:G to T:A mutations. We have compared two mutants of M. EcoRII that are defective for catalysis by the wild-type enzyme for their ability to bind DNA containing U:G or T:G mismatches and for their ability to promote C to T mutations. We find that although all three proteins are able to bind DNAs with mismatches, only the wild-type enzyme promotes C:G to T:A mutations in vivo. Therefore, the ability of M. EcoRII to bind U:G mismatched duplexes is not sufficient for their mutagenic action in cells.
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Received: 14 November 1996 / Accepted: 17 February 1997
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Sheluho, D., Yebra, M., Khariwala, S. et al. Lack of correlation between binding of Eco RII methyltransferase to DNA duplexes containing mismatches and the promotion of C to T mutations. Mol Gen Genet 255, 54–59 (1997). https://doi.org/10.1007/s004380050474
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DOI: https://doi.org/10.1007/s004380050474