Effects of the N terminus of mouse DNA polymerase {kappa} on the bypass of a guanine-benzo[a]pyrenyl adduct

DNA polymerase (Pol), one of the typical member of the Y-family DNA polymerases, has been demonstrated to bypass the 10S (+)-trans-anti-benzo[a]pyrene diol epoxide-N2-deoxyguanine adducts (BPDE-dG) efficiently and accurately. A large structural gap between the core and little finger as well as an N-clasp domain are essential to its unique translesion capability. However, whether the extreme N-terminus of Pol is required for its activity is unclear. In this work, we constructed two mouse Pol deletions, which have either a catalytic core (mPol1-516) or a core without the first 21-residues (mPol22-516), and tested their activities in the replication of normal and BPDE-DNA. These two Pol deletions are nearly as efficient as the full length protein (Pol1-852) in normal DNA synthesis. However, steady-state kinetics reveals a significant reduction in efficiency of dCTP incorporation opposite the lesion by Pol22-516, along with increased frequencies for misinsertion compared with Pol1-852. The next nucleotide insertion opposite the template C immediately following the BPDE-dG was also examined, and the bypass differences induced by deletions were highlighted in both insertion and extension step. We conclude that the extreme N-terminal part of Pol is required for the processivity and fidelity of Pol during translesion synthesis of BPDE-dG lesions.

Source: Journal of Biochemistry - March 20, 2016 Category: Biochemistry Authors: Liu, Y., Ma, X., Guo, C. Tags: Regular Papers Source Type: research