Substrate specificity of RusA resolvase reveals the DNA structures targeted by RuvAB and RecG in vivo
Substrate specificity of RusA resolvase reveals the DNA structures targeted by RuvAB and RecG in vivo
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DOI：
10.1016/s1097-2765(02)00560-9
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发表时间：
2002-07-01
期刊：
影响因子：
16
通讯作者：
Lloyd, RG
中科院分区：
文献类型：
--
作者：
Bolt, EL;Lloyd, RG
RusA内切核酸酶通过在CC二核苷酸的5'端引入成对的链切口来切割霍利迪连接。当同二聚体的两个亚基同时与对称定位的裂解位点相互作用时，实现配位催化。这一要求赋予了霍利迪连接特异性。当结合相互作用受到干扰时，发生解偶联催化。遗传学研究表明，解偶联很少发生在体内，因此DNA切割仅限于霍利迪连接。我们利用RusA的特异性来鉴定体内RuvAB和RecG分支迁移蛋白靶向的DNA底物。我们提出的证据表明，在紫外线照射的细胞中的复制重新启动依赖于处理停滞的复制叉由RecG解旋酶和霍利迪路口的RuvABC resolvasome，和RuvAB单独可能不会促进修复。
RusA endonuclease cleaves Holliday junctions by introducing paired strand incisions 5' to CC dinucleotides. Coordinated catalysis is achieved when both subunits of the homodimer interact simultaneously with cleavage sites located symmetrically. This requirement confers Holliday junction specificity. Uncoupled catalysis occurs when binding interactions are disturbed. Genetic studies indicate that uncoupling occurs rarely in vivo, and DNA cleavage is therefore restricted to Holliday junctions. We exploited the specificity of RusA to identify the DNA substrates targeted by the RuvAB and RecG branch-migration proteins in vivo. We present evidence that replication restart in UV-irradiated cells relies on the processing of stalled replication forks by RecG helicase and of Holliday junctions by the RuvABC resolvasome, and that RuvAB alone may not promote repair.