Response of human REV1 to different DNA damage: preferential dCMP insertion opposite the lesion

摘要

REV1 functions in the DNA polymerase ζ mutagenesis pathway. To help understand the role of REV1 in lesion bypass, we have examined activities of purified human REV1 opposite various template bases and several different DNA lesions. Lacking a 3'→5' proofreading exonuclease activity, purified human REV1 exhibited a DNA polymerase activity on a repeating template G sequence, but catalyzed nucleotide insertion with 6-fold lower efficiency opposite a template A and 19-27-fold lower efficiency opposite a template T or c. Furthermore, dCMP insertion was greatly preferred regardless of the specific template base. Human REV1 inserted a dCMP efficiently opposite a template 8-oxoguanine, (+)-trans-anti-benzo[a]pyrene-N~2-dG, (-)-trans-antibenzo[a]pyrene-N~2-dG and 1,N~6-ethenoadenine adducts, very inefficiently opposite an acetylamino-fluorene-adducted guanine, but was unresponsive to a template TT dimer or TT (6-4) photoproduct. Surprisingly, the REV1 specificity of nucleotide insertion was very similar in response to different DNA lesions with greatly preferred C insertion and least frequent A insertion. By combining the dCMP insertion activity of human REV1 with the extension synthesis activity of human polymerase κ, bypass of the trans-anti-benzo[a]pyrene-N~2-dG adducts and the 1, N~6-ethenoadenine lesion was achieved by the two-polymerase two-step mechanism. These results suggest that human REV1 is a specialized DNA polymerase that may contribute to dCMP insertion opposite many types of DNa damage during lesion bypass.