Murayama Yasuto, Iwasaki Hiroshi
Cancer Research UK, London Research Institute, 44, Lincoln's Inn Fields, London, WC2A 3LY, UK.
Methods Mol Biol. 2011;745:385-405. doi: 10.1007/978-1-61779-129-1_22.
DNA strand exchange is a core reaction of homologous recombination directly catalyzed by Rad51/Dmc1 RecA family recombinases in eukaryotes. This reaction proceeds through the formation of several DNA intermediates. The X-shaped four-way DNA structure known as a Holliday junction (HJ) is a central intermediate in homologous recombination. Genetic and biochemical studies indicate that the HJ is important for the production of crossover-type recombinants, which are reciprocal exchange products. According to a recombination model for the repair of DNA double-strand breaks, the formation of HJs requires a reciprocal duplex-duplex DNA exchange known as the DNA four-strand exchange reaction. In vitro analyses using purified recombination proteins and model DNA substrates provide a mechanistic insight into the DNA strand exchange reaction, including the steps leading to the formation and branch migration of Holliday junctions.
DNA链交换是真核生物中由Rad51/Dmc1 RecA家族重组酶直接催化的同源重组的核心反应。该反应通过形成几种DNA中间体进行。被称为霍利迪连接体（HJ）的X形四链DNA结构是同源重组的核心中间体。遗传和生化研究表明，HJ对于产生交叉型重组体（即相互交换产物）很重要。根据DNA双链断裂修复的重组模型，HJ的形成需要一种称为DNA四链交换反应的双链-双链DNA相互交换。使用纯化的重组蛋白和模型DNA底物进行的体外分析为DNA链交换反应提供了机制上的见解，包括导致霍利迪连接体形成和分支迁移的步骤。
