DNA ligase I fidelity mediates the mutagenic ligation of pol β oxidized and mismatch nucleotide insertion products in base excision repair.
DNA ligase I fidelity mediates the mutagenic ligation of pol β oxidized and mismatch nucleotide insertion products in base excision repair.
复制标题
DOI：
10.1016/j.jbc.2021.100427
复制
发表时间：
2021-01
期刊：
影响因子：
--
通讯作者：
Çağlayan M
中科院分区：
文献类型：
--
作者：
Kamble P;Hall K;Chandak M;Tang Q;Çağlayan M
DNA 连接酶 I (LIG1) 在 DNA 聚合酶 (pol) β 缺口填充 DNA 合成后的最后一个切口密封步骤中完成碱基切除修复 (BER) 途径。然而，LIG1 保真度在 BER 途径的最后步骤中介导忠实的底物-产物通道和修复中间体连接的机制仍不清楚。我们之前报道过 pol β 8-oxo-2'-脱氧核糖核苷 5'-三磷酸插入混淆了 LIG1，导致形成带有 5'-腺苷酸块的连接失败产物。在这里，我们使用体外重构的 BER 测定，报告了 pol β 8-oxo-2'-脱氧核糖核苷 5'-三磷酸插入产物的诱变连接，以及保真度受到干扰的 LIG1 突变体 (E346A/E592A) 对 pol β Watson-Crick 样 dG:T 错配插入的低效连接。此外，我们的结果表明，LIG1 对预插入 3'-8-oxodG 或错配的切口修复中间体的底物区分是由 E346 和 E592 残基的突变控制的。最后，我们发现aprataxin和flap核酸内切酶1作为补偿性DNA末端加工酶，可以从含有3'-8-oxodG或12个可能的非规范碱基对的失败连接产物中去除5'-腺苷酸片段。这些发现有助于理解LIG1作为忠实BER中重要决定因素的作用，以及多蛋白复合物（LIG1、pol β、aprataxin和flap核酸内切酶1）如何协调以防止在BER途径下游步骤中形成末端受损或不匹配的诱变修复中间体。
DNA ligase I (LIG1) completes the base excision repair (BER) pathway at the last nick-sealing step after DNA polymerase (pol) β gap-filling DNA synthesis. However, the mechanism by which LIG1 fidelity mediates the faithful substrate–product channeling and ligation of repair intermediates at the final steps of the BER pathway remains unclear. We previously reported that pol β 8-oxo-2'-deoxyribonucleoside 5'-triphosphate insertion confounds LIG1, leading to the formation of ligation failure products with a 5'-adenylate block. Here, using reconstituted BER assays in vitro, we report the mutagenic ligation of pol β 8-oxo-2'-deoxyribonucleoside 5'-triphosphate insertion products and an inefficient ligation of pol β Watson–Crick–like dG:T mismatch insertion by the LIG1 mutant with a perturbed fidelity (E346A/E592A). Moreover, our results reveal that the substrate discrimination of LIG1 for the nicked repair intermediates with preinserted 3'-8-oxodG or mismatches is governed by mutations at both E346 and E592 residues. Finally, we found that aprataxin and flap endonuclease 1, as compensatory DNA-end processing enzymes, can remove the 5'-adenylate block from the abortive ligation products harboring 3'-8-oxodG or the 12 possible noncanonical base pairs. These findings contribute to the understanding of the role of LIG1 as an important determinant in faithful BER and how a multiprotein complex (LIG1, pol β, aprataxin, and flap endonuclease 1) can coordinate to prevent the formation of mutagenic repair intermediates with damaged or mismatched ends at the downstream steps of the BER pathway.
登录
查看更多内容
影响因子：
3.8
作者：
Çağlayan M
通讯作者：
Çağlayan M
DOI：
10.1107/s0907444904019158
发表时间：
2004-12-01
影响因子：
2.2
作者：
Emsley, P;Cowtan, K
通讯作者：
Cowtan, K
影响因子：
14.9
作者：
Caglayan, Melike;Horton, Julie K.;Wilson, Samuel H.
通讯作者：
Wilson, Samuel H.
影响因子：
4.1
作者：
Ahn, JW;Kraynov, VS;Tsai, MD
通讯作者：
Tsai, MD
影响因子：
4.6
作者：
Caglayan, Melike
通讯作者：
Caglayan, Melike