The Werner syndrome protein limits the error-prone 8-oxo-dG lesion bypass activity of human DNA polymerase kappa.

ABSTRACT: Human DNA polymerase kappa (hpol ?) is the only Y-family member to preferentially insert dAMP opposite 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-oxo-dG) during translesion DNA synthesis. We have studied the mechanism of action by which hpol ? activity is modulated by the Werner syndrome protein (WRN), a RecQ helicase known to influence repair of 8-oxo-dG. Here we show that WRN stimulates the 8-oxo-dG bypass activity of hpol ? in vitro by enhancing the correct base insertion opposite the lesion, as well as extension from dC:8-oxo-dG base pairs. Steady-state kinetic analysis reveals that WRN improves hpol ?-catalyzed dCMP insertion opposite 8-oxo-dG ?10-fold and extension from dC:8-oxo-dG by 2.4-fold. Stimulation is primarily due to an increase in the rate constant for polymerization (kpol), as assessed by pre-steady-state kinetics, and it requires the RecQ C-terminal (RQC) domain. In support of the functional data, recombinant WRN and hpol ? were found to physically interact through the exo and RQC domains of WRN, and co-localization of WRN and hpol ? was observed in human cells treated with hydrogen peroxide. Thus, WRN limits the error-prone bypass of 8-oxo-dG by hpol ?, which could influence the sensitivity to oxidative damage that has previously been observed for Werner's syndrome cells.

SUBMITTER: Maddukuri L 

PROVIDER: S-EPMC4231769 | biostudies-literature | 2014 Oct

REPOSITORIES: biostudies-literature