Capturing a mammalian DNA polymerase extending from an oxidized nucleotide.
Capturing a mammalian DNA polymerase extending from an oxidized nucleotide.
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捕获从氧化核苷酸延伸的哺乳动物 DNA 聚合酶。
DOI：
10.1093/nar/gkx293
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发表时间：
2017
影响因子：
14.9
通讯作者：
Freudenthal,BretD
中科院分区：
文献类型：
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作者：
Whitaker,AmyM;Smith,MalloryR;Schaich,MatthewA;Freudenthal,BretD
8-氧代-7，8-二氢-2脱氧鸟苷(8-΄-deoxguanosine，8-oxoG)是DNA损伤中含量最丰富的一种。8-oxoG在肿瘤发生和人类疾病中发挥重要作用。8-oxoG的生物学后果部分是通过它插入基因组来调节的，这使得了解DNA聚合酶如何处理8-oxoG是至关重要的。8-oxoG插入对腺嘌呤时有致突变作用，但对胞嘧啶插入时无致突变作用。然而，在随后的插入事件中，这两种结果都会导致引物末端(3΄-End)的DNA损伤。对DNA损伤在引物末端的延伸仍然知之甚少。利用动力学和时间推移结晶学，我们评估了一个模型DNA聚合酶，人聚合酶β，如何在与胞嘧啶和腺嘌呤相对的引物末端调节8-oxoG。值得注意的是，突变碱基对的延伸比非突变碱基对更受欢迎。当8-oxoG位于与胞嘧啶相对的引物末端时，DNA中心的变化导致8-oxoG的O8与磷酸骨架发生碰撞。活性中心改变引起的延伸反应的变化为Arg254和Asp256之间的稳定相互作用提供了证据，这种相互作用在DNA合成反应中发挥着重要作用。这些结果为研究引物末端的损伤对基因组稳定性和DNA合成的影响提供了新的见解。
The oxidized nucleotide, 8-oxo-7,8-dihydro-2΄-deoxyguanosine (8-oxoG), is one of the most abundant DNA lesions. 8-oxoG plays a major role in tumorigenesis and human disease. Biological consequences of 8-oxoG are mediated in part by its insertion into the genome, making it essential to understand how DNA polymerases handle 8-oxoG. Insertion of 8-oxoG is mutagenic when opposite adenine but not when opposite cytosine. However, either result leads to DNA damage at the primer terminus (3΄-end) during the succeeding insertion event. Extension from DNA damage at primer termini remains poorly understood. Using kinetics and time-lapse crystallography, we evaluated how a model DNA polymerase, human polymerase β, accommodates 8-oxoG at the primer terminus opposite cytosine and adenine. Notably, extension from the mutagenic base pair is favored over the non-mutagenic base pair. When 8-oxoG is at the primer terminus opposite cytosine, DNA centric changes lead to a clash between O8 of 8-oxoG and the phosphate backbone. Changes in the extension reaction resulting from the altered active site provide evidence for a stabilizing interaction between Arg254 and Asp256 that serves an important role during DNA synthesis reactions. These results provide novel insights into the impact of damage at the primer terminus on genomic stability and DNA synthesis.