Nucleic Acids Research, 2003, Vol. 31, No. 10 2570-2575
© 2003 Oxford University Press
Mutagenic effects of 2-hydroxy-dATP on replication in a HeLa extract: induction of substitution and deletion mutations
Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi-6, Kita-ku, Sapporo 060-0812, Japan
*To whom correspondence should be addressed. Tel: +81 11 706 3733; Fax: +81 11 706 4879; Email: hirokam{at}pharm.hokudai.acjp
The mutagenicity of an oxidized form of dATP, 2-hydroxydeoxyadenosine 5'-triphosphate (2-OH-dATP), was examined using an SV40 origin-dependent in vitro replication system with a HeLa extract. 2-OH-dATP induced mutations in a dose-dependent manner and elicited substitution and deletion mutations. Of the substitutions, a G·C
A·T transition including a tandem (CCTT) mutation was mainly observed. This result agrees with our previous observation that mammalian DNA polymerase 
misincorporates the oxidized nucleotide opposite C, but is in contrast to the finding that 2-OH-dATP elicits G·CT·A transversions in Escherichia coli. This type of mutation was also elicited, but to a lesser extent. Interestingly, the mutagenicity of 2-OH-dATP was enhanced in the presence of 2-hydroxydeoxyadenosine 5'-diphosphate, an inhibitor of the MTH1 protein, suggesting that this protein functions in the hydrolysis of 2-OH-dATP in the replication reaction mixture, and probably in living cells. These results indicate that 2-OH-dATP is mutagenic and that its mutagenicity is suppressed by the MTH1 protein in mammalian cells.