West S C
Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, Hertfordshire, United Kingdom.
Annu Rev Genet. 1997;31:213-44. doi: 10.1146/annurev.genet.31.1.213.
The RuvA, RuvB, and RuvC proteins in Escherichia coli play important roles in the late stages of homologous genetic recombination and the recombinational repair of damaged DNA. Two proteins, RuvA and RuvB, form a complex that promotes ATP-dependent branch migration of Holliday junctions, a process that is important for the formation of heteroduplex DNA. Individual roles for each protein have been defined, with RuvA acting as a specificity factor that targets RuvB, the branch migration motor to the junction. Structural studies indicate that two RuvA tetramers sandwich the junction and hold it in an unfolded square-planar configuration. Hexameric rings of RuvB face each other across the junction and promote a novel dual helicase action that "pumps" DNA through the RuvAB complex, using the free energy provided by ATP hydrolysis. The third protein, RuvC endonuclease, resolves the Holliday junction by introducing nicks into two DNA strands. Genetic and biochemical studies indicate that branch migration and resolution are coupled by direct interactions between the three proteins, possibly by the formation of a RuvABC complex.
大肠杆菌中的RuvA、RuvB和RuvC蛋白在同源基因重组的后期以及受损DNA的重组修复过程中发挥着重要作用。RuvA和RuvB这两种蛋白形成一个复合物，促进霍利迪连接体（Holliday junction）的ATP依赖性分支迁移，这一过程对于异源双链DNA的形成至关重要。已明确了每种蛋白的具体作用，RuvA作为一种特异性因子，将分支迁移马达蛋白RuvB靶向连接体。结构研究表明，两个RuvA四聚体将连接体夹在中间，并使其保持在未折叠的平面正方形构型。RuvB的六聚体环在连接体两侧相对，促进一种新的双解旋酶作用，利用ATP水解提供的自由能将DNA“泵”过RuvAB复合物。第三种蛋白RuvC核酸内切酶通过在两条DNA链上引入切口来拆分霍利迪连接体。遗传和生化研究表明，分支迁移和拆分通过这三种蛋白之间的直接相互作用而偶联在一起，可能是通过形成RuvABC复合物来实现的。
