Tsaneva I R, Müller B, West S C
Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, Hertfordshire, United Kingdom.
Proc Natl Acad Sci U S A. 1993 Feb 15;90(4):1315-9. doi: 10.1073/pnas.90.4.1315.
The SOS-inducible ruvA and ruvB gene products of Escherichia coli are required for normal levels of genetic recombination and DNA repair. In vitro, RuvA protein interacts specifically with Holliday junctions and, together with RuvB (an ATPase), promotes their movement along DNA. This process, known as branch migration, is important for the formation of heteroduplex DNA. In this paper, we show that the RuvA and RuvB proteins promote the unwinding of partially duplex DNA. Using single-stranded circular DNA substrates with annealed fragments (52-558 nucleotides in length), we show that RuvA and RuvB promote strand displacement with a 5'-->3' polarity. The reaction is ATP-dependent and its efficiency is inversely related to the length of the duplex DNA. These results show that the ruvA and ruvB genes encode a DNA helicase that specifically recognizes Holliday junctions and promotes branch migration.
大肠杆菌中SOS诱导的ruvA和ruvB基因产物是正常水平的基因重组和DNA修复所必需的。在体外，RuvA蛋白与霍利迪连接体特异性相互作用，并与RuvB（一种ATP酶）一起促进它们沿DNA移动。这个过程称为分支迁移，对异源双链DNA的形成很重要。在本文中，我们表明RuvA和RuvB蛋白促进部分双链DNA的解旋。使用带有退火片段（长度为52 - 558个核苷酸）的单链环状DNA底物，我们表明RuvA和RuvB以5'→3'极性促进链置换。该反应是ATP依赖性的，其效率与双链DNA的长度成反比。这些结果表明ruvA和ruvB基因编码一种特异性识别霍利迪连接体并促进分支迁移的DNA解旋酶。
