Anderson D G, Kowalczykowski S C
Genetics Graduate Group, University of California, Davis, 95616-8665, USA.
Cell. 1997 Jul 11;90(1):77-86. doi: 10.1016/s0092-8674(00)80315-3.
Double-stranded DNA break repair and homologous recombination in E. coli are initiated by the RecBCD enzyme, which unwinds and simultaneously degrades DNA from a double-stranded DNA end. This process is stimulated by cis-acting DNA elements, known as chi sites. Using both in vitro pairing and nuclease protection assays, we demonstrate that the translocating RecBCD enzyme, which has been activated by chi, coordinates the preferential loading of the homologous pairing protein, RecA, onto the resultant single-stranded DNA downstream of chi. This facilitated loading of RecA protein results in a substantial increase in both the efficiency and rate of in vitro recombination reactions and offers an explanation for stimulation of recombination and repair in vivo by chi.
大肠杆菌中的双链DNA断裂修复和同源重组由RecBCD酶启动，该酶从双链DNA末端解开并同时降解DNA。这一过程受到顺式作用DNA元件（称为chi位点）的刺激。通过体外配对和核酸酶保护试验，我们证明，已被chi激活的易位RecBCD酶协调同源配对蛋白RecA优先加载到chi下游产生的单链DNA上。RecA蛋白的这种促进加载导致体外重组反应的效率和速率大幅提高，并为chi在体内刺激重组和修复提供了解释。
