Single-turnover kinetic analysis of the mutagenic potential of 8-oxo-7,8-dihydro-2′-deoxyguanosine during gap-filling synthesis catalyzed by human DNA polymerases λ and β
Single-turnover kinetic analysis of the mutagenic potential of 8-oxo-7,8-dihydro-2′-deoxyguanosine during gap-filling synthesis catalyzed by human DNA polymerases λ and β
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DOI：
10.1016/j.jmb.2007.01.069
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发表时间：
2007-04-13
影响因子：
5.6
通讯作者：
Suo, Zucai
中科院分区：
文献类型：
--
作者：
Brown, Jessica A.;Duym, Wade W.;Suo, Zucai
在8-oxo-7，8-dihydro-2 '-deoxyguanosine（8-oxodG）损伤的存在下，许多DNA聚合酶表现出双编码潜力，其促进匹配的dCTP或错配的dATP的有效掺入。这也适用于8-oxodGTP相对于模板碱基dC和dA的插入。人DNA聚合酶λ，以确定当分别遇到8-oxodG和8-oxodGTP时哪个核苷酸和模板碱基是优选。虽然DNA聚合酶β优先掺入dCTP超过dATP，但DNA聚合酶λ在与单核苷酸缺口DNA中的8-oxodG相对时不调节对dCTP或dATP的偏好，因为掺入以基本上相等的效率和概率进行。此外，DNA聚合酶λ比DNA聚合酶β更有效地填充这种氧化的单核苷酸缺口。插入8-oxodGTP的DNA聚合酶λ和β主要发生在对模板dA，从而重申如何不对称的设计的聚合酶活性位点差异容纳反和顺式构象的8-oxodG和8-oxodGTP。尽管8-oxodG的C8位置处的电负性氧可诱导DNA结构扰动，但发现人DNA连接酶I有效地将掺入的8-oxodGMP连接到下游链，其密封有切口的DNA。因此，由DNA聚合酶λ和β催化的错误的核苷酸重复以及随后在碱基切除修复期间由DNA连接酶催化的连接是对基因组完整性的威胁。(c)2007爱思唯尔有限公司保留所有权利。
In the presence of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) damage, many DNA polymerases exhibit a dual coding potential which facilitates efficient incorporation of matched dCTP or mismatched dATP This also holds true for the insertion of 8-oxodGTP opposite template bases dC and dA. Employing single-turnover kinetic methods, we examined human DNA polymerase beta and its novel X-family homolog, human DNA polymerase lambda, to determine which nucleotide and template base was preferred when encountering 8-oxodG and 8-oxodGTP, respectively. While DNA polymerase beta preferentially incorporated dCTP over dATP, DNA polymerase lambda did not modulate a preference for either dCTP or dATP when opposite 8-oxodG in single-nucleotide gapped DNA, as incorporation proceeded with essentially equal efficiency and probability. Moreover, DNA polymerase lambda is more efficient than DNA polymerase beta to fill this oxidized single-nucleotide gap.. Insertion of 8-oxodGTP by both DNA polymerases lambda and beta occurred predominantly against template dA, thereby reiterating how the asymmetrical design of the polymerase active site differentially accommodated the anti and syn conformations of 8-oxodG and 8-oxodGTP. Although the electronegative oxygen at the C8 position of 8-oxodG may induce DNA structural perturbations, human DNA ligase I was found to effectively ligate the incorporated 8-oxodGMP to a downstream strand, which sealed the nicked DNA. Consequently, the erroneous nucleotide incorporations catalyzed by DNA polymerases lambda and beta as well as the subsequent ligation catalyzed by a DNA ligase during base excision repair are a threat to genomic integrity. (c) 2007 Elsevier Ltd. All rights reserved.