Nucleotide incorporation by human DNA polymerase γ opposite benzo[a]pyrene and benzo[c]phenanthrene diol epoxide adducts of deoxyguanosine and deoxyadenosine
Nucleotide incorporation by human DNA polymerase γ opposite benzo[a]pyrene and benzo[c]phenanthrene diol epoxide adducts of deoxyguanosine and deoxyadenosine
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DOI：
10.1093/nar/gkh213
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发表时间：
2004-01-01
影响因子：
14.9
通讯作者：
Copeland, WC
中科院分区：
文献类型：
--
作者：
Graziewicz, MA;Sayer, JM;Copeland, WC
线粒体是苯并[a]芘(BaP)的主要细胞靶标，BaP是一种已知的致癌物质，也能抑制线粒体的增殖。在这里，我们首次报道了来自BaP 7，8-二醇9，10-环氧化物(BaP DE)的N-2-脱氧鸟苷(DG)和N-6-脱氧腺苷(Da)加合物(BaP DE)和来自苯并[c]菲3，4-二醇1，2-环氧化物(BcPh DE)的加合物(BcPh DE)对具有和不具有P55加工性亚单位的外切酶缺陷型人线粒体DNA聚合酶(PolGamma)复制的影响。单独的催化亚基主要与BaP的DE-DG加合物相反的DAMP和dGMP错结合，并且与来自BaP和BcPh的DE-da加合物相反的正确的DTMP以及错误的DAMP结合。在P55存在的情况下，聚合酶结合了所有四个核苷酸，并催化有限的跨损伤合成通过BaP DE-DG加合物，而不是BaP或BcPh DE-da加合物。因此，所有这些加合物都会导致错误的嘌呤掺入，并显著阻碍引物的进一步延伸。与Bap DE-DG加合物相反的polGamma错误掺入嘌呤类似于Y家族polETA观察到的情况。这些DE加合物对跨病变合成的阻断与已知BaP对线粒体(Mt)DNA合成的抑制是一致的，表明持续暴露于BaP会减少mtDNA拷贝数，增加与先前存在的突变mtDNA重新繁殖的机会，从而增加线粒体遗传病的风险。
Mitochondria are major cellular targets of benzo[a]pyrene (BaP), a known carcinogen that also inhibits mitochondrial proliferation. Here, we report for the first time the effect of site-specific N-2-deoxyguanosine (dG) and N-6-deoxyadenosine (dA) adducts derived from BaP 7,8-diol 9,10-epoxide (BaP DE) and dA adducts from benzo[c]phenanthrene 3,4-diol 1,2-epoxide (BcPh DE) on DNA replication by exonuclease-deficient human mitochondrial DNA polymerase (pol gamma) with and without the p55 processivity subunit. The catalytic subunit alone primarily misincorporated dAMP and dGMP opposite the BaP DE-dG adducts, and incorporated the correct dTMP as well as the incorrect dAMP opposite the DE-dA adducts derived from both BaP and BcPh. In the presence of p55 the polymerase incorporated all four nucleotides and catalyzed limited translesion synthesis past BaP DE-dG adducts but not past BaP or BcPh DE-dA adducts. Thus, all these adducts cause erroneous purine incorporation and significant blockage of further primer elongation. Purine misincorporation by pol gamma opposite the BaP DE-dG adducts resembles that observed with the Y family pol eta. Blockage of translesion synthesis by these DE adducts is consistent with known BaP inhibition of mitochondrial (mt)DNA synthesis and suggests that continued exposure to BaP reduces mtDNA copy number, increasing the opportunity for repopulation with pre-existing mutant mtDNA and a resultant risk of mitochondrial genetic diseases.