Werner's syndrome protein limits the error‐prone 8‐oxo‐G lesion bypass activity of human DNA polymerase kappa by promoting the error‐free bypass

Abstract

Oxidative stress induced DNA damage plays a key role in cancer and aging. 7,8‐dihydro‐8oxo‐2′‐deoxyguanosine (8‐oxo‐dG), produced during DNA oxidation is highly mutagenic and known to block replication. Previous studies show that the human DNA polymerase kappa (hpol κ) bypasses 8‐oxo‐dG by preferentially inserting dATP opposite the lesion. Recent studies indicated that hpol κ coordinates with Werner's syndrome protein (WRN) during the 8‐oxo‐dG bypass. Our data show that WRN stimulates the 8‐oxo‐dG bypass activity of hpol κ by enhancing the correct base insertion opposite the lesion and diminishing the efficiency of dATP mispair insertion. Kinetic analysis reveals that in the presence of WRN, hpol κ inserts the dCTP opposite 8‐oxo‐dG ~ 1.7‐fold more efficiently than dCTP opposite dG. Currently we are investigating the fidelity and catalytic efficiency of hpol κ bypass of 8‐oxo‐dG in the presence of WRN using pre‐steady state kinetic analysis and mass spectrometric detection of polymerization products. WRN may function in coordination with hpol κ to limit the error‐prone bypass of 8‐oxo‐dG, which could suppress the mutagenicity associated with hpol κ and prevent genomic instability. This work is supported in part by USPHS R00 GM084460 (R.L.E).