Recognition and manipulation of branched DNA by the RusA Holliday junction resolvase of Escherichia coli
Recognition and manipulation of branched DNA by the RusA Holliday junction resolvase of Escherichia coli
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DOI：
10.1093/nar/26.7.1560
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发表时间：
1998-04-01
影响因子：
14.9
通讯作者：
Lloyd, RG
中科院分区：
文献类型：
--
作者：
Chan, SN;Vincent, SD;Lloyd, RG
同源重组是一个基本的细胞过程，它塑造和重塑所有生物体的基因组并促进受损DNA的修复，该过程中的关键步骤是通过同源DNA配对和链交换形成的Holliday连接的解析。在大肠杆菌中，通过RuvA和RuvB蛋白的协同活动，Holliday连接被加工成重组产物，RuvA和RuvB蛋白一起驱动分支迁移，和RuvC核酸内切酶，其解析结构。在不存在RuvABC的情况下，可以通过增加RusA内切核酸酶的表达来促进重组，所述RusA内切核酸酶是由隐蔽原噬菌体基因编码的Holliday连接解离酶。在这里，我们描述了RusA的DNA结合特性。我们发现，RusA对分支分子具有高度选择性，并且即使在存在大量过量的线性双链体DNA的情况下也与这些结构形成复合物。然而，它与线性双链体DNA的结合较弱。在与双链体DNA没有可检测的结合的条件下，RusA与合成的霍利迪连接形成高度结构化的复合物，该复合物非常稳定并且对二价金属离子不敏感。发现双链体臂在该复合物内采用特定的对齐方式，该复合物近似于接头的四面体构象。
Homologous recombination is a fundamental cellular process that shapes and reshapes the genomes of all organisms and promotes repair of damaged DNA, A key step in this process is the resolution of Holliday junctions formed by homologous DNA pairing and strand exchange, In Escherichia coli, a Holliday junction is processed into recombinant products by the concerted activities of the RuvA and RuvB proteins, which together drive branch migration, and RuvC endonuclease, which resolves the structure. In the absence of RuvABC, recombination can be promoted by increasing the expression of the RusA endonuclease, a Holliday junction resolvase encoded by a cryptic prophage gene, Here, we describe the DNA binding properties of RusA, We found that RusA was highly selective for branched molecules and formed complexes with these structures even in the presence of a large excess of linear duplex DNA, However, it does bind weakly to linear duplex DNA, Under conditions where there was no detectable binding to duplex DNA, RusA formed a highly structured complex with a synthetic Holliday junction that was remarkably stable and insensitive to divalent metal ions. The duplex arms were found to adopt a specific alignment within this complex that approximated to a tetrahedral conformation of the junction.