Biochemical characterization of eight genetic variants of human DNA polymerase κ involved in error-free bypass across bulky N(2)-guanyl DNA adducts.

Song I, Kim EJ, Kim IH, Park EM, Lee KE, Shin JH, Guengerich FP, Choi JY
Chem Res Toxicol. 2014 27 (5): 919-30

PMID: 24725253 · PMCID: PMC7002036 · DOI:10.1021/tx500072m

DNA polymerase (pol) κ, one of the Y-family polymerases, has been shown to function in error-free translesion DNA synthesis (TLS) opposite the bulky N(2)-guanyl DNA lesions induced by many carcinogens such as polycyclic aromatic hydrocarbons. We analyzed the biochemical properties of eight reported human pol κ variants positioned in the polymerase core domain, using the recombinant pol κ (residues 1-526) protein and the DNA template containing an N(2)-CH2(9-anthracenyl)G (N(2)-AnthG). The truncation R219X was devoid of polymerase activity, and the E419G and Y432S variants showed much lower polymerase activity than wild-type pol κ. In steady-state kinetic analyses, E419G and Y432S displayed 20- to 34-fold decreases in kcat/Km for dCTP insertion opposite G and N(2)-AnthG compared to that of wild-type pol κ. The L21F, I39T, and D189G variants, as well as E419G and Y432S, displayed 6- to 22-fold decreases in kcat/Km for next-base extension from C paired with N(2)-AnthG, compared to that of wild-type pol κ. The defective Y432S variant had 4- to 5-fold lower DNA-binding affinity than wild-type, while a slightly more efficient S423R variant possessed 2- to 3-fold higher DNA-binding affinity. These results suggest that R219X abolishes and the E419G, Y432S, L21F, I39T, and D189G variations substantially impair the TLS ability of pol κ opposite bulky N(2)-G lesions in the insertion step opposite the lesion and/or the subsequent extension step, raising the possibility that certain nonsynonymous pol κ genetic variations translate into individual differences in susceptibility to genotoxic carcinogens.

MeSH Terms (8)

DNA-Directed DNA Polymerase DNA Adducts Genetic Variation Humans Models, Molecular Mutation Protein Structure, Tertiary Recombinant Proteins

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