A mechanistic basis for Mre11-directed DNA joining at microhomologies
A mechanistic basis for Mre11-directed DNA joining at microhomologies
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DOI：
10.1073/pnas.110144297
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发表时间：
2000-06-06
影响因子：
11.1
通讯作者：
Gellert, M
中科院分区：
文献类型：
--
作者：
Paull, TT;Gellert, M
脊椎动物细胞中DNA双链断裂的修复主要通过末端连接过程发生，该过程通常产生具有几个核苷酸序列同源性的连接。Mre 11对于芽殖酵母中的这种修复模式至关重要，并且与基于微同源性的连接有关。这里.我们表明Mre 11核酸外切酶活性对异源DNA的存在是敏感的。以及其末端的结构和顺序。添加错配的DNA末端刺激DNA被Mre 11降解。此外，如果在降解过程中发现序列同一性，则会导致Mrell核酸酶活性暂停，从而稳定微同源位点处的连接。一个仍然结合DNA的核酸酶缺陷型Mre 11突变体也可以刺激野生型Mrell的降解。提示Mre 11-DNA复合物可能相互作用以桥接DNA末端并促进DNA连接。
Repair of DNA double-strand breaks in vertebrate cells occurs mainly by an end-joining process that often generates junctions with sequence homologies of a few nucleotides. Mre11 is critical for this mode of repair in budding yeast and has been implicated in the microhomology-based joining. Here. we show that Mre11 exonuclease activity is sensitive to the presence of heterologous DNA. and to the structure and sequence of its ends. Addition of mismatched DNA ends stimulates degradation of DNA by Mre11. whereas cohesive ends strongly inhibit it. Furthermore, if a sequence identity is revealed during the course of degradation, it causes Mrell nuclease activity to pause, thus stabilizing the junction at a site of microhomology. A nuclease-deficient Mre11 mutant that still binds DNA can also stimulate degradation by wild-type Mrell. suggesting that Mre11-DNA complexes may interact to bridge DNA ends and facilitate DNA joining.