The efficiency and fidelity of 8-oxo-guanine bypass by DNA polymerases delta and eta

Nucleic Acids Res. 2009 May;37(9):2830-40. doi: 10.1093/nar/gkp103. Epub 2009 Mar 12.


A DNA lesion created by oxidative stress is 7,8-dihydro-8-oxo-guanine (8-oxoG). Because 8-oxoG can mispair with adenine during DNA synthesis, it is of interest to understand the efficiency and fidelity of 8-oxoG bypass by DNA polymerases. We quantify bypass parameters for two DNA polymerases implicated in 8-oxoG bypass, Pols delta and eta. Yeast Pol delta and yeast Pol eta both bypass 8-oxoG and misincorporate adenine during bypass. However, yeast Pol eta is 10-fold more efficient than Pol delta, and following bypass Pol eta switches to less processive synthesis, similar to that observed during bypass of a cis-syn thymine-thymine dimer. Moreover, yeast Pol eta is at least 10-fold more accurate than yeast Pol delta during 8-oxoG bypass. These differences are maintained in the presence of the accessory proteins RFC, PCNA and RPA and are consistent with the established role of Pol eta in suppressing ogg1-dependent mutagenesis in yeast. Surprisingly different results are obtained with human and mouse Pol eta. Both mammalian enzymes bypass 8-oxoG efficiently, but they do so less processively, without a switch point and with much lower fidelity than yeast Pol eta. The fact that yeast and mammalian Pol eta have intrinsically different catalytic properties has potential biological implications.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural

MeSH terms

  • Animals
  • DNA / biosynthesis
  • DNA Polymerase III / metabolism*
  • DNA-Directed DNA Polymerase / metabolism*
  • Guanine / analogs & derivatives*
  • Guanine / chemistry
  • Humans
  • Mice
  • Saccharomyces cerevisiae / enzymology


  • 8-hydroxyguanine
  • Guanine
  • DNA
  • DNA Polymerase III
  • DNA-Directed DNA Polymerase
  • Rad30 protein