Interactions of the DNA ligase IV-XRCC4 complex with DNA ends and the DNA-dependent protein kinase
Interactions of the DNA ligase IV-XRCC4 complex with DNA ends and the DNA-dependent protein kinase
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DOI：
10.1074/jbc.m000491200
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发表时间：
2000-08-25
影响因子：
4.8
通讯作者：
Tomkinson, AE
中科院分区：
文献类型：
--
作者：
Chen, L;Trujillo, K;Tomkinson, AE
由Ku和DNA-PK催化亚基(DNA-PKcs)组成的DNA依赖蛋白激酶(DNA-PK)和DNA连接酶IV-XRCC4复合体共同参与DNA双链断裂的非同源末端连接修复。这些蛋白质复合体也是免疫细胞完成V(D)J重组事件所必需的，在这里，我们证明了DNA连接酶IV-XRCC4复合体与双链DNA分子的末端特异结合，并可以作为桥梁因子，将双链DNA分子与互补但不可连接的末端连接在一起。尽管DNA末端结合蛋白Ku抑制了DNA连接酶IV-XRCC4与DNA的结合，但它并没有阻止该复合体与DNA的结合，相反，DNA连接酶TVXRCC4和Ku同时结合到双链DNA分子的末端。DNA连接酶TV-XRCC4和DNA-PKcs也在DNA分子末端形成复合体，但DNA-PKcs不抑制连接，有趣的是，DNA-PKcs促进DNA连接酶Tv-XRCC4的分子间连接，在DNA-PK的存在下，由于Ku抑制分子内连接，DNA连接酶IV-XRCC4催化的大部分连接事件是分子间的，但DNA-PKcs仍然刺激分子内连接，我们认为DNA末端形成的含DNA-PKcs的复合体通过蛋白质-蛋白质相互作用促进DNA末端的结合，从而刺激分子间连接。
The DNA-dependent protein kinase (DNA-PK), consisting of Ku and the DNA-PK catalytic subunit (DNA-PKcs), and the DNA ligase IV-XRCC4 complex function together in the repair of DNA double-strand breaks by non-homologous end joining. These protein complexes are also required for the completion of V(D)J recombination events in immune cells, Here we demonstrate that the DNA ligase IV-XRCC4 complex binds specifically to the ends of duplex DNA molecules and can act as a bridging factor, linking together duplex DNA molecules with complementary but non-ligatable ends. Although the DNA end-binding protein Ku inhibited DNA joining by DNA ligase IV-XRCC4, it did not prevent this complex from binding to DNA, Instead, DNA ligase TVXRCC4 and Ku bound simultaneously to the ends of duplex DNA molecules. DNA ligase TV-XRCC4 and DNA-PKcs also formed complexes at the ends of DNA molecules, but DNA-PKcs did not inhibit ligation, Interestingly, DNA-PKcs stimulated intermolecular ligation by DNA ligase TV-XRCC4, In the presence of DNA-PK, the majority of the joining events catalyzed by DNA ligase IV-XRCC4 were intermolecular because Ku inhibited intramolecular ligation, but DNA-PKcs still stimulated intramolecular ligation, We suggest that DNA-PKcs-containing complexes formed at DNA ends enhance the association of DNA ends via protein-protein interactions, thereby stimulating intermolecular ligation.