RecG helicase promotes DNA double-strand break repair
RecG helicase promotes DNA double-strand break repair
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DOI：
10.1111/j.1365-2958.2003.03970.x
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发表时间：
2004-04-01
影响因子：
3.6
通讯作者：
Lloyd, RG
中科院分区：
文献类型：
--
作者：
Meddows, TR;Savory, AP;Lloyd, RG
双链断裂对基因组构成了重大威胁，如果要保持结构和功能的完整性，必须准确修复。这通常通过同源重组来实现，这使得断裂的DNA分子的末端能够接合完整的双链体并引发修复所需的DNA的合成。在大肠杆菌中，修复依赖于RecBCD和RecA蛋白，其启动重组和形成联合分子中间体的组合能力是众所周知的。为了阐明后续事件，我们利用酵母的I-SceI归巢核酸内切酶在染色体中工程化的I-SceI切割位点处进行断裂。我们发现，生存依赖于RecA和RecBCD，随后的事件可以通过两种途径，一种依赖于RuvABC霍利迪交界处resolvase和其他RecG解旋酶进行。这两种途径都依赖于PriA，可能是为了促进DNA复制。我们讨论的可能性，经典霍利迪路口可能不是必不可少的中间体修复和考虑替代途径的RecG依赖性分离的联合分子形成的RecA。
Double-strand breaks pose a major threat to the genome and must be repaired accurately if structural and functional integrity are to be preserved. This is usually achieved via homologous recombination, which enables the ends of a broken DNA molecule to engage an intact duplex and prime synthesis of the DNA needed for repair. In Escherichia coli, repair relies on the RecBCD and RecA proteins, the combined ability of which to initiate recombination and form joint-molecule intermediates is well understood. To shed light on subsequent events, we exploited the I-SceI homing endonuclease of yeast to make breaks at I-SceI cleavage sites engineered into the chromosome. We show that survival depends on RecA and RecBCD, and that subsequent events can proceed via either of two pathways, one dependent on the RuvABC Holliday junction resolvase and the other on RecG helicase. Both pathways rely on PriA, presumably to facilitate DNA replication. We discuss the possibility that classical Holliday junctions may not be essential intermediates in repair and consider alternative pathways for RecG-dependent separation of joint molecules formed by RecA.