The efficiency and fidelity of 8-oxo-guanine bypass by DNA polymerases delta and eta.
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.
McCulloch
Scott D
SD
Laboratory of Molecular Genetics and Laboratory of Structural Biology, National Institute of Environmental Health Sciences Research, NC 27709, USA.
Kokoska
Robert J
RJ
Garg
Parie
P
Burgers
Peter M
PM
Kunkel
Thomas A
TA
D000818:Animals; D004247:DNA / Q000096:biosynthesis; D004258:DNA Polymerase III / Q000378:metabolism*; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D006147:Guanine / Q000031:analogs & derivatives* / Q000737:chemistry; D006801:Humans; D051379:Mice; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D000099270:Y-Family DNA Polymerases
D004247:DNA; D004258:DNA Polymerase III; D004259:DNA-Directed DNA Polymerase; D006147:Guanine; C024829:8-hydroxyguanine; C112338:Rad30 protein; D000099270:Y-Family DNA Polymerases