8-oxo-guanine bypass by human DNA polymerases in the presence of auxiliary proteins
8-oxo-guanine bypass by human DNA polymerases in the presence of auxiliary proteins
复制标题
DOI：
10.1038/nature05843
复制
发表时间：
2007-05-31
期刊：
影响因子：
64.8
通讯作者：
Huebscher, Ulrich
中科院分区：
文献类型：
--
作者：
Maga, Giovanni;Villani, Giuseppe;Huebscher, Ulrich
特殊的DNA聚合酶（DNA pols）需要在人类细胞中进行病变旁路(1)。辅助因素有一个重要的作用，但迄今为止人们对其了解甚少。在这里，我们分析了人类增殖细胞核抗原（PCNA）和复制蛋白A （RP-A）在不同病变的体外搭桥过程中对六种不同的人类DNA极点（属于B类，Y类和X类）的影响。致突变损伤8-氧鸟嘌呤（8-氧-g）具有很高的错误编码潜力（2-4）。8-oxo-G旁路对DNA极点lambda和eta具有主要和特异性的影响。PCNA和RP-A允许dCTP与8-oxo-G模板正确结合，其效率分别比DNA pol lambda和DNA pol eta的错误dATP高1200倍和68倍。DNA-pol-lambda-null细胞提取物的实验表明，DNA pol-lambda具有重要的作用。另一方面，DNA pol - iota与DNA pol - a、delta和β一起显示出较低的正确旁路效率。我们的研究结果表明，存在一种精确的机制来减少氧化损伤的有害后果，此外，还指出PCNA和RP-A在确定病变旁路中不同DNA点之间的功能等级方面发挥重要作用。
Specialized DNA polymerases (DNA pols) are required for lesion bypass in human cells(1). Auxiliary factors have an important, but so far poorly understood, role. Here we analyse the effects of human proliferating cell nuclear antigen (PCNA) and replication protein A (RP-A) on six different human DNA pols - belonging to the B, Y and X classes - during in vitro bypass of different lesions. The mutagenic lesion 8-oxo-guanine (8-oxo-G) has high miscoding potential(2-4). A major and specific effect was found for 8-oxo-G bypass with DNA pols lambda and eta. PCNA and RP-A allowed correct incorporation of dCTP opposite a 8-oxo-G template 1,200-fold more efficiently than the incorrect dATP by DNA pol lambda, and 68-fold by DNA pol eta, respectively. Experiments with DNA-pol-lambda-null cell extracts suggested an important role for DNA pol lambda. On the other hand, DNA pol iota, together with DNA pols a, delta and beta, showed a much lower correct bypass efficiency. Our findings show the existence of an accurate mechanism to reduce the deleterious consequences of oxidative damage and, in addition, point to an important role for PCNA and RP-A in determining a functional hierarchy among different DNA pols in lesion bypass.