ATP-dependent interaction of human mismatch repair proteins and dual role of PCNA in mismatch repair
ATP-dependent interaction of human mismatch repair proteins and dual role of PCNA in mismatch repair
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DOI：
10.1093/nar/26.5.1173
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发表时间：
1998-03-01
影响因子：
14.9
通讯作者：
Li, GM
中科院分区：
文献类型：
--
作者：
Gu, LY;Hong, Y;Li, GM
DNA错配修复通过纠正生物合成错误和阻断同源重组来确保基因组的稳定性。MutS样和MutL样蛋白在这些过程中发挥重要作用。在大肠杆菌和酵母中，这两种类型的蛋白质形成与错配DNA结合的修复起始复合物，然而，人MutS和MutL同源物是否相互作用形成复合物尚未阐明。本文利用免疫沉淀和Western印迹分析表明，人MSH2、MLH1、PMS2和增殖细胞核抗原（PCNA）可以免疫共沉淀，这表明在这些蛋白质中形成了修复起始复合物。起始复合物的形成依赖于ATP水解和至少功能性MSH2和MLH1蛋白，因为在产生截短的MLH1或MSH2蛋白的肿瘤细胞中不能检测到复合物。我们还表明，PCNA是需要在人类错配修复不仅在修复启动的步骤，但也在修复DNA再合成的步骤。
DNA mismatch repair ensures genomic stability by correcting biosynthetic errors and by blocking homologous recombination. MutS-like and MutL-like proteins play important roles in these processes. In Escherichia coli and yeast these two types of proteins form a repair initiation complex that binds to mismatched DNA, However, whether human MutS and MutL homologs interact to form a complex has not been elucidated, Using immunoprecipitation and Western blot analysis we show here that human MSH2, MLH1, PMS2 and proliferating cell nuclear antigen (PCNA) can be co-immunoprecipitated, suggesting formation of a repair initiation complex among these proteins. Formation of the initiation complex is dependent on ATP hydrolysis and at least functional MSH2 and MLH1 proteins, because the complex could not be detected in tumor cells that produce truncated MLH1 or MSH2 protein. We also demonstrate that PCNA is required in human mismatch repair not only at the step of repair initiation, but also at the step of repair DNA re-synthesis.