Unnatural substrates reveal the importance of 8-oxoguanine for in vivo mismatch repair by MutY
Unnatural substrates reveal the importance of 8-oxoguanine for in vivo mismatch repair by MutY
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DOI：
10.1038/nchembio.2007.40
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发表时间：
2008-01-01
影响因子：
14.8
通讯作者：
David, Sheila S.
中科院分区：
文献类型：
--
作者：
Livingston, Alison L.;O'Shea, Valerie L.;David, Sheila S.
大肠杆菌MutY在防止与DNA中的氧化损伤7，8-二氢-8-氧代-2 '-脱氧鸟苷（OG）相关的突变中具有重要作用，其通过从OG中心点A错配中切除腺嘌呤作为碱基切除修复的第一步。为了确定MutY的碱基对识别和碱基去除过程中特定步骤的重要性，我们评估了OG中心点A底物的修饰对基于大肠杆菌的测定中碱基去除、错配亲和力和修复G-C的动力学的影响。值得注意的是，腺嘌呤修饰在细胞测定中是耐受的，而OG的修饰导致最小的细胞修复。对错配的高亲和力和有效的碱基去除需要OG的存在。综上所述，这些结果表明，OG的存在是MutY定位OG中心点A错配并选择合适的腺嘌呤进行切除以在复制前启动体内修复所必需的关键特征。
Escherichia coli MutY has an important role in preventing mutations associated with the oxidative lesion 7,8-dihydro-8-oxo-2'-deoxyguanosine (OG) in DNA by excising adenines from OG center dot A mismatches as the first step of base excision repair. To determine the importance of specific steps in the base pair recognition and base removal process of MutY, we have evaluated the effects of modifications of the OG center dot A substrate on the kinetics of base removal, mismatch affinity and repair to G-C in an E coli-based assay. Notably, adenine modification was tolerated in the cellular assay, whereas modification of OG resulted in minimal cellular repair. High affinity for the mismatch and efficient base removal required the presence of OG. Taken together, these results suggest that the presence of OG is a critical feature that is necessary for MutY to locate OG center dot A mismatches and select the appropriate adenines for excision to initiate repair in vivo before replication.