Yu X, West S C, Egelman E H
Department of Cell Biology and Neuroanatomy, University of Minnesota Medical School, Minneapolis 55455, USA.
J Mol Biol. 1997 Feb 21;266(2):217-22. doi: 10.1006/jmbi.1996.0799.
The E. coli RuvA and RuvB proteins, which are involved in the late stages of recombination and the recombinational repair of damaged DNA, bind to Holliday junctions and promote branch migration. We have used electron microscopy and image analysis to examine RuvA and RuvB bound to model Holliday structures. The two hexameric rings of RuvB are oriented in a bipolar manner, so that the large end of each faces the junction. The results suggest a model for branch migration in which DNA is pumped out of the small end of each ring as ATP is hydrolyzed. The same structural polarity has been established for the bacteriophage T7 gp4 replicative helicase. Mass and image analysis of the RuvAB-junction complex suggests that two tetramers of RuvA form a symmetrical sandwich about the plane of the junction.
参与重组后期和受损DNA重组修复的大肠杆菌RuvA和RuvB蛋白与霍利迪连接体结合并促进分支迁移。我们利用电子显微镜和图像分析来检测与模型霍利迪结构结合的RuvA和RuvB。RuvB的两个六聚体环以双极方式排列，使得每个环的大端面向连接体。结果提示了一种分支迁移模型，即随着ATP水解，DNA从小端泵出。噬菌体T7 gp4复制解旋酶也具有相同的结构极性。RuvAB-连接体复合物的质量和图像分析表明，两个RuvA四聚体围绕连接体平面形成对称三明治结构。
