Translesion synthesis across O6-alkylguanine DNA adducts by recombinant human DNA polymerases
Translesion synthesis across O6-alkylguanine DNA adducts by recombinant human DNA polymerases
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DOI：
10.1074/jbc.m608369200
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发表时间：
2006-12-15
影响因子：
4.8
通讯作者：
Guengerich, F. Peter
中科院分区：
文献类型：
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作者：
Choi, Jeong-Yun;Chowdhury, Goutam;Guengerich, F. Peter
先前的研究表明，复制性细菌和病毒DNA聚合酶能够绕过致突变性病变O-6-甲基和-苄基(Bz) G。重组人聚合酶(pol) delta也复制通过这两个病变，但被O-6-[4-氧代-4-(3-吡啶基)丁基](Pob)G完全阻断，这是一种重要的致突变性病变 烟草特有致癌物 4-(甲基亚硝基氨基)-1-(3-吡啶基)-1-丁酮代谢激活后形成。人类跨损伤pols iota和kappa主要只产生与O-6-MeG和O-6-BzG相反的1个碱基掺入，并且在复制O-6-PobG方面具有非常低的活性。人类 pol eta 复制了所有三个加合物。稳态动力学分析显示 dCTP 和 dTTP 与 pol eta 和 kappa 相对 O-6-烷基G 加合物的插入效率相似； pol iota 对 dTTP 表现出强烈的偏好。 pol eta、iota 和 kappa 显示了与 G 和 O-6-MeG 相对的 dCTP 掺入的前稳态动力学爆发，但对于 O-6-BzG 或 O-6-PobG 而言，几乎没有（如果有的话）。 pol eta O-6-PobG 产物的分析表明，G 的插入位于加合物的碱基 (C) 5' 的对面，但该产物没有延伸。所有 pol eta 引物延伸产物的质谱分析表明存在多种成分，主要是 C 或 T 插入相反的 O-6-烷基G，但在 O-6-MeG 和 O-6-PobG 的情况下没有删除。使用 pol eta 和 O-6-BzG，还获得了具有 -1 和 -2 缺失以及 A 插入（与 O-6-BzG 相反）的产物。 pol eta 的结果可能与之前报道的哺乳动物细胞中 O-6-烷基G 加合物的一些突变有关。
Previous studies have shown that replicative bacterial and viral DNA polymerases are able to bypass the mutagenic lesions O-6-methyl and -benzyl (Bz) G. Recombinant human polymerase (pol) delta also copied past these two lesions but was totally blocked by O-6-[4-oxo-4-(3-pyridyl) butyl] (Pob)G, an important mutagenic lesion formed following metabolic activation of the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone. The human translesion pols iota and kappa produced mainly only 1-base incorporation opposite O-6-MeG and O-6-BzG and had very low activity in copying O-6-PobG. Human pol eta copied past all three adducts. Steady-state kinetic analysis showed similar efficiencies of insertion opposite the O-6-alkylG adducts for dCTP and dTTP with pol eta and kappa; pol iota showed a strong preference for dTTP. pol eta, iota, and kappa showed pre-steady-state kinetic bursts for dCTP incorporation opposite G and O-6-MeG but little, if any, for O-6-BzG or O-6-PobG. Analysis of the pol eta O-6-PobG products indicated that the insertion of G was opposite the base (C) 5' of the adduct, but this product was not extended. Mass spectrometry analysis of all of the pol eta primer extension products indicated multiple components, mainly with C or T inserted opposite O-6-alkylG but with no deletions in the cases of O-6-MeG and O-6-PobG. With pol eta and O-6-BzG, products were also obtained with -1 and -2 deletions and also with A inserted (opposite O-6-BzG). The results with pol eta may be relevant to some mutations previously reported with O-6-alkylG adducts in mammalian cells.