The efficiency and fidelity of 8-oxo-guanine bypass by DNA polymerases δ and η

Laboratory of Molecular Genetics and Laboratory of Structural Biology, National Institute of Environmental Health Sciences Research, NC 27709, USA.
Nucleic Acids Research (Impact Factor: 9.11). 04/2009; 37(9):2830-40. DOI: 10.1093/nar/gkp103
Source: PubMed

ABSTRACT 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.

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Available from: Scott D Mcculloch, Aug 22, 2015
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    • "Commonly encountered base modifications such as 8-oxo- deoxyguanine or 6-methyl-deoxyguanine can be used as templates by a replicating Pol d with reduced efficiency, but the altered base pairing properties of these lesions usually results in a mispair that pol d is not able to extend [Fazlieva et al., 2009; McCulloch et al., 2009]. When Pol d encounters an abasic site, it has a tendency to incorporate an adenine, possibly due to a highly conserved tyrosine (Y708) which acts as a mock template, and which has a more favorable electrostatic interaction with adenine [Schaaper et al., 1983; Obeid et al., 2010]. "
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    Environmental and Molecular Mutagenesis 12/2012; 53(9). DOI:10.1002/em.21745 · 2.55 Impact Factor
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    • "Furthermore, this enzyme was reportedly able to bypass not only UV-induced lesions but also various other lesions induced by both environmental and endogenous reactive oxygen species. For instance, HsPolη bypasses 7,8-dihydro- 8-oxoguanine (8-oxoG), 5R-thymine glycol (5R-Tg), and 5S- thymine glycol (5S-Tg), but not an apurinic/apyrimidinic (AP) site [13] [14] [15] [16] [17] [18] [19], although these lesions, which have small alterations in their chemical structures, are mainly repaired by BER in vivo. Thus, these findings indicate that HsPolη also plays an important function in the replication of DNA containing ROS-induced lesions in vivo. "
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    • "The incorporation of 2'-deoxyribonucleotides opposite 8-OH-Gua by human DNA pol η was analyzed in vitro. Human DNA pol η incorporates dATP and dCTP opposite the lesion with comparable efficiencies, but proliferating cell nuclear antigen (PCNA) and replication protein A (RP-A) enhance the correct 8-OH-Gua bypass [25] [26] [27] [28] [29] [30]. The mammalian replicative DNA pols α and δ are error-prone against 8-OH-Gua [27] [28] [42] [43] [44] [45] [46] [47]. "
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