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Quantitative analysis of the mutagenic potential of 1-aminopyrene-DNA adduct bypass catalyzed by Y-family DNA polymerases.

ABSTRACT: N-(Deoxyguanosin-8-yl)-1-aminopyrene (dG(AP)) is the predominant nitro polyaromatic hydrocarbon product generated from the air pollutant 1-nitropyrene reacting with DNA. Previous studies have shown that dG(AP) induces genetic mutations in bacterial and mammalian cells. One potential source of these mutations is the error-prone bypass of dG(AP) lesions catalyzed by the low-fidelity Y-family DNA polymerases. To provide a comparative analysis of the mutagenic potential of the translesion DNA synthesis (TLS) of dG(AP), we employed short oligonucleotide sequencing assays (SOSAs) with the model Y-family DNA polymerase from Sulfolobus solfataricus, DNA Polymerase IV (Dpo4), and the human Y-family DNA polymerases eta (hPol?), kappa (hPol?), and iota (hPol?). Relative to undamaged DNA, all four enzymes generated far more mutations (base deletions, insertions, and substitutions) with a DNA template containing a site-specifically placed dG(AP). Opposite dG(AP) and at an immediate downstream template position, the most frequent mutations made by the three human enzymes were base deletions and the most frequent base substitutions were dAs for all enzymes. Based on the SOSA data, Dpo4 was the least error-prone Y-family DNA polymerase among the four enzymes during the TLS of dG(AP). Among the three human Y-family enzymes, hPol? made the fewest mutations at all template positions except opposite the lesion site. hPol? was significantly less error-prone than hPol? and hPol? during the extension of dG(AP) bypass products. Interestingly, the most frequent mutations created by hPol? at all template positions were base deletions. Although hRev1, the fourth human Y-family enzyme, could not extend dG(AP) bypass products in our standing start assays, it preferentially incorporated dCTP opposite the bulky lesion. Collectively, these mutagenic profiles suggest that hPolk and hRev1 are the most suitable human Y-family DNA polymerases to perform TLS of dG(AP) in humans.

SUBMITTER: Sherrer SM

PROVIDER: S-EPMC3448278 | biostudies-literature | 2012 Sep

REPOSITORIES: biostudies-literature

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Quantitative analysis of the mutagenic potential of 1-aminopyrene-DNA adduct bypass catalyzed by Y-family DNA polymerases.

Sherrer Shanen M SM Taggart David J DJ Pack Lindsey R LR Malik Chanchal K CK Basu Ashis K AK Suo Zucai Z

Mutation research 20120814 1-2

N-(Deoxyguanosin-8-yl)-1-aminopyrene (dG(AP)) is the predominant nitro polyaromatic hydrocarbon product generated from the air pollutant 1-nitropyrene reacting with DNA. Previous studies have shown that dG(AP) induces genetic mutations in bacterial and mammalian cells. One potential source of these mutations is the error-prone bypass of dG(AP) lesions catalyzed by the low-fidelity Y-family DNA polymerases. To provide a comparative analysis of the mutagenic potential of the translesion DNA synthe ...[more]

PMID: 22917544

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Project description:Translesion synthesis (TLS) of the N(2)-2'-deoxyguanosine (dG-N(2)-IQ) adduct of the carcinogen 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) was investigated in human embryonic kidney 293T cells by replicating plasmid constructs in which the adduct was individually placed at each guanine (G1, G2, or G3) of the NarI sequence (5'-CG1G2CG3CC-3'). TLS efficiency was 38%, 29%, and 25% for the dG-N(2)-IQ located at G1, G2, and G3, respectively, which suggests that dG-N(2)-IQ is bypassed more efficiently by one or more DNA polymerases at G1 than at either G2 or G3. TLS efficiency was decreased 8-35% in cells with knockdown of pol ?, pol ?, pol ?, pol ?, or Rev1. Up to 75% reduction in TLS occurred when pol ?, pol ?, and Rev1 were simultaneously knocked down, suggesting that these three polymerases play important roles in dG-N(2)-IQ bypass. Mutation frequencies (MFs) of dG-N(2)-IQ at G1, G2, and G3 were 23%, 17%, and 11%, respectively, exhibiting a completely reverse trend of the previously reported MF of the C8-dG adduct of IQ (dG-C8-IQ), which is most mutagenic at G3 ( ( 2015 ) Nucleic Acids Res. 43 , 8340 - 8351 ). The major type of mutation induced by dG-N(2)-IQ was targeted G ? T, as was reported for dG-C8-IQ. In each site, knockdown of pol ? resulted in an increase in MF, whereas MF was reduced when pol ?, pol ?, pol ?, or Rev1 was knocked down. The reduction in MF was most pronounced when pol ?, pol ?, and Rev1 were simultaneously knocked down and especially when the adduct was located at G3, where MF was reduced by 90%. We conclude that pol ? predominantly performs error-free TLS of the dG-N(2)-IQ adduct, whereas pols ?, pol ?, and Rev1 cooperatively carry out the error-prone TLS. However, in vitro experiments using yeast pol ? and ? showed that the former was inefficient in full-length primer extension on dG-N(2)-IQ templates, whereas the latter was efficient in both error-free and error-prone extensions. We believe that the observed differences between the in vitro experiments using purified DNA polymerases, and the cellular results may arise from several factors including the crucial roles played by the accessory proteins in TLS.

Dataset Information

Quantitative analysis of the mutagenic potential of 1-aminopyrene-DNA adduct bypass catalyzed by Y-family DNA polymerases.

Publications

Quantitative analysis of the mutagenic potential of 1-aminopyrene-DNA adduct bypass catalyzed by Y-family DNA polymerases.

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