Bypassing a 8,5'-cyclo-2'-deoxyadenosine lesion by human DNA polymerase η at atomic resolution.
Bypassing a 8,5'-cyclo-2'-deoxyadenosine lesion by human DNA polymerase η at atomic resolution.
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人类 DNA 聚合酶 γ 在原子分辨率下绕过 8,5-环-2-脱氧腺苷损伤。
DOI：
10.1073/pnas.1812856115
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发表时间：
2018
影响因子：
11.1
通讯作者：
Yang,Wei
中科院分区：
文献类型：
--
作者：
Weng,PeterJ;Gao,Yang;Gregory,MarkT;Wang,Pengcheng;Wang,Yinsheng;Yang,Wei
氧化诱导的DNA损伤8，5‘-环嘌呤-2’-脱氧核苷(CdPus)广泛存在，通过阻碍DNA复制和转录而产生细胞毒性。CdPu的5‘R-和5’S-非对映体均可通过核苷酸切除修复去除，但5‘S-cdPu比5’R-cdPu更耐修复。在这里，我们报告了绕过5‘S-8，5’-环-2‘-脱氧腺苷插入和随后的两个延伸步骤的人聚合酶(POL)η的晶体结构。含有CDA的DNA结构因蛋白质环境的不同而不同。在POLη“分子夹板”的支持下，5‘S-CDA在1.75ra分辨率下的结构表明，脊椎被挤压向小沟，腺嘌呤基座倾斜。在模板位置，CDA占据了通常为胸腺嘧啶二聚体保留的额外空间，并且在Mn2+存在的情况下，dTTP被POLη有效地结合。然而，CDA对DNA二聚体的刚性扭曲阻碍了正常的碱基配对，并阻碍了POLη的即时引物延伸。我们的结果为细胞中cdPu损伤的强烈复制阻断效应和突变特性提供了结构上的见解。
Oxidatively induced DNA lesions 8,5′-cyclopurine-2′-deoxynucleosides (cdPus) are prevalent and cytotoxic by impeding DNA replication and transcription. Both the 5′R- and 5′S-diastereomers of cdPu can be removed by nucleotide excision repair; however, the 5′S-cdPu is more resistant to repair than the 5′Rcounterpart. Here, we report the crystal structures of human polymerase (Pol) η bypassing 5′S-8,5′-cyclo-2′-deoxyadenosine (cdA) in insertion and the following two extension steps. The cdA-containing DNA structures vary in response to the protein environment. Supported by the “molecular splint” of Pol η, the structure of 5′S-cdA at 1.75-Å resolution reveals that the backbone is pinched toward the minor groove and the adenine base is tilted. In the templating position, the cdA takes up the extra space usually reserved for the thymine dimer, and dTTP is efficiently incorporated by Pol η in the presence of Mn2+. Rigid distortions of the DNA duplex by cdA, however, prevent normal base pairing and hinder immediate primer extension by Pol η. Our results provide structural insights into the strong replication blockage effect and the mutagenic property of the cdPu lesions in cells.