DNA-Protein Interactions Unit, Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol, BS8 1TD, United Kingdom.
DNA Repair (Amst). 2010 Mar 2;9(3):276-85. doi: 10.1016/j.dnarep.2009.12.016. Epub 2010 Jan 29.
Double-stranded DNA breaks are prepared for recombinational repair by nucleolytic digestion to form single-stranded DNA overhangs that are substrates for RecA/Rad51-mediated strand exchange. This processing can be achieved through the activities of multiple helicases and nucleases. In bacteria, the function is mainly provided by a stable multi-protein complex of which there are two structural classes; AddAB- and RecBCD-type enzymes. These helicase-nucleases are of special interest with respect to DNA helicase mechanism because they are exceptionally powerful DNA translocation motors, and because they serve as model systems for both single molecule studies and for understanding how DNA helicases can be coupled to other protein machinery. This review discusses recent developments in our understanding of the AddAB and RecBCD complexes, focussing on their distinctive strategies for processing DNA ends. We also discuss the extent to which bacterial DNA end resection mechanisms may parallel those used in eukaryotic cells.
双链 DNA 断裂通过核酶消化为单链 DNA 突出端进行重组修复，这些单链 DNA 突出端是 RecA/Rad51 介导的链交换的底物。这种处理可以通过多种解旋酶和核酸酶的活性来实现。在细菌中，该功能主要由一个稳定的多蛋白复合物提供，该复合物有两种结构类型；AddAB-和 RecBCD 型酶。这些解旋酶-核酸酶对于 DNA 解旋酶机制特别感兴趣，因为它们是非常强大的 DNA 易位马达，并且它们是用于单分子研究以及理解 DNA 解旋酶如何与其他蛋白质机器偶联的模型系统。本综述讨论了我们对 AddAB 和 RecBCD 复合物的理解的最新进展，重点讨论了它们处理 DNA 末端的独特策略。我们还讨论了细菌 DNA 末端切除机制在多大程度上与真核细胞中使用的机制相似。
