The role of the SAP motif in promoting Holliday junction binding and resolution by SpCCE1
The role of the SAP motif in promoting Holliday junction binding and resolution by SpCCE1
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DOI：
10.1074/jbc.m302314200
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发表时间：
2003-08-01
影响因子：
4.8
通讯作者：
Whitby, MC
中科院分区：
文献类型：
--
作者：
Ahn, JS;Whitby, MC
霍利迪连接是四向分支的DNA结构，在重组过程中形成，并通过复制叉回归。它们的加工依赖于催化连接分支迁移的解旋酶和将连接分解成带切口的线性DNA的核酸内切酶。在这里，我们已经调查了一个DNA结合基序称为SAP在结合和解决霍利迪路口的裂殖酵母线粒体解离酶SpCCE 1的作用。SAP基序的突变或部分/完全缺失显著削弱了SpCCE 1在异源体内系统中解析Holliday连接的能力。这些突变蛋白保留了识别连接结构并在结合时使其变形的能力。然而，一旦形成，突变蛋白质-连接复合物相对不稳定，并且比野生型复合物解离快得多。我们表明，结合稳定性是必要的有效的交界处的决议，这可能是由于在一个开放的构象，使它可以分支迁移到可切割的网站保持交界处的要求。
Holliday junctions are four-way branched DNA structures that are formed during recombination and by replication fork regression. Their processing depends on helicases that catalyze junction branch migration, and endonucleases that resolve the junction into nicked linear DNAs. Here we have investigated the role of a DNA binding motif called SAP in binding and resolving Holliday junctions by the fission yeast mitochondrial resolvase SpCCE1. Mutation or partial/complete deletion of the SAP motif dramatically impairs the ability of SpCCE1 to resolve Holliday junctions in a heterologous in vivo system. These mutant proteins retain the ability to recognize the junction structure and to distort it upon binding. However, once formed the mutant protein-junction complexes are relatively unstable and dissociate much faster than wild-type complexes. We show that binding stability is necessary for efficient junction resolution, and that this may be due in part to a requirement for maintaining the junction in an open conformation so that it can branch migrate to cleavable sites.