Activity of DNA ligase IV stimulated by complex formation with XRCC4 protein in mammalian cells
Activity of DNA ligase IV stimulated by complex formation with XRCC4 protein in mammalian cells
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DOI：
10.1038/41358
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发表时间：
1997-07-31
期刊：
影响因子：
64.8
通讯作者：
Lieber, MR
中科院分区：
文献类型：
--
作者：
Grawunder, U;Wilm, M;Lieber, MR
哺乳动物细胞中XRCC 4基因的突变（1，2）阻止了V（D）J重组反应中信号和编码接头的形成（3），这是产生功能性免疫球蛋白基因所必需的，并使细胞对电离辐射高度敏感（4）。然而，XRCC 4与其他蛋白质没有序列同源性，也没有生物化学活性来表明其功能可能是什么（2）。在这里，我们表明，DNA连接酶IV（参考文献5）与XRCC 4共免疫沉淀，这两种蛋白质特异性相互作用，在酵母双杂交系统。通过DNA连接酶IV在无细胞系统中连接DNA双链断裂通过纯化的XRCC 4增加了5倍，当XRCC 4与DNA连接酶IV共表达时增加了7至8倍。我们得出结论，突变XRCC 4的生物学后果主要是由于其对DNA连接酶IV的刺激作用的丧失：XRCC 4-DNA连接酶IV复合物的功能可能是进行V（D）J重组和DNA末端连接的最后步骤。
Mutation of the XRCC4 gene in mammalian cells(1,2) prevents the formation of the signal and coding joints in the V(D)J recombination reaction(3), which is necessary for production of a functional immunoglobulin gene, and renders the cells highly sensitive to ionizing radiation(4). However, XRCC4 shares no sequence homology with other proteins, nor does it have a biochemical activity to indicate what its function might be(2). Here we show that DNA ligase IV (ref. 5) co-immunoprecipitates with XRCC4 and that these two proteins specifically interact with one another in a yeast two-hybrid system. Ligation of DNA double-strand breaks in a cell-free system by DNA ligase IV is increased fivefold by purified XRCC4 and seven- to eightfold when XRCC4 is co-expressed with DNA ligase IV. We conclude that the biological consequences of mutating XRCC4 are primarily due to the loss of its stimulatory effect on DNA ligase IV: the function of the XRCC4-DNA ligase IV complex may be to carry out the final steps of V(D)J recombination and joining of DNA ends.