Translesion DNA synthesis catalyzed by human pol eta and pol kappa across 1,N-6-ethenodeoxyadenosine

1,N-6-Ethenodeoxyadenosine, a DNA adduct generated by exogenous and endogen ous sources, severely blocks DNA synthesis and induces miscoding events in human cells. To probe the mechanism for in vivo translesion DNA synthesis a cross this adduct, in vitro primer extension studies were conducted using n ewly identified human DNA polymerases (pol) eta and kappa, which have been shown to catalyze translesion DNA synthesis past several DNA lesions. Stead y-state kinetic analyses and analysis of translesion products have revealed that the synthesis is > 100-fold more efficient with pol eta than with pol K and that both error-free and error-prone syntheses are observed with the se enzymes. The miscoding events include both base substitution and framesh ift mutations. These results suggest that both polymerases, particularly po l eta, may contribute to the translesion DNA synthesis events observed for 1,N-6-ethenodeoxyadenosine in human cells.