8-oxodGTP incorporation by DNA polymerase beta is modified by active-site residue Asn279 |
| |
Authors: | Miller H Prasad R Wilson S H Johnson F Grollman A P |
| |
Institution: | Department of Pharmacological Sciences, SUNY Stony Brook, Stony Brook, New York 11794-8651, USA. miller@pharm.sunysb.edu |
| |
Abstract: | To understand how the active site of a DNA polymerase might modulate the coding of 8-oxo-7,8-dihydrodeoxyguanine (8-oxodG), we performed steady-state kinetic analyses using wild-type DNA polymerase beta (pol beta) and two active-site mutants. We compared the coding of these polymerases by calculating the ratio of efficiencies for incorporation of dATP and dCTP opposite 8-oxodG and for incorporation of 8-oxodGTP opposite dA and dC. For wild-type pol beta, there is a 2:1 preference for incorporation of dCTP over dATP opposite 8-oxodG using a 5'-phosphorylated 4-base gap substrate. Mutation of either Asn279 or Arg283 to alanine has almost no effect on the ratio. 8-OxodGTP is preferentially incorporated opposite a template dA (24:1) by wild-type pol beta; mutation of Asn279 to alanine results dramatic change whereby there is preferential incorporation of 8-oxodGTP opposite dC (14:1). This suggests that interactions of 8-oxodGTP with Asn279 in the polymerase active site may alter the conformation of 8-oxodGTP and therefore alter its misincorporation. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|