A Comparative Study for Incorporation of 8-oxo-dATP in DNA by Human DNA Polymerases

In this work, we analyzed the ability to incorporate 8-oxo-dATP by several human DNA polymerases: replicative Pol ε (exo-), BER enzymes Pol β and Pol λ, and trans-lesion Pol η, Pol ι, and Pol κ. We demonstrated that human DNA polymerases differ in their abilities to discriminate against 8-oxo-dATP. Among tested DNA polymerases, Pol λ demonstrated the worst ability to discriminate against 8-oxo-dATP opposite template T on both singles-stranded DNA and double-stranded DNA substrates with a 1 nt gap. In contrast, Pol β was quite accurate on singe-stranded DNA substrate but incorporated 8-oxo-dATP opposite template T in a 1 nt gap. Unexpectedly, the catalytic subunit of high-fidelity Pol ε (exo-) incorporated 8-oxodATP opposite templates T and G with weak but higher efficiency compare to error-prone polymerases of Family Y. While structures of human polymerases with incoming 8oxo-dATP are not available, we speculate possible mechanism of 8-oxo-dATP discriminations.