Sugiyama Tomohiko, Kantake Noriko, Wu Yun, Kowalczykowski Stephen C
Department of Biological Sciences, Ohio University, Athens, OH 45701, USA.
EMBO J. 2006 Nov 29;25(23):5539-48. doi: 10.1038/sj.emboj.7601412. Epub 2006 Nov 9.
Rad51, Rad52, and RPA play central roles in homologous DNA recombination. Rad51 mediates DNA strand exchange, a key reaction in DNA recombination. Rad52 has two distinct activities: to recruit Rad51 onto single-strand (ss)DNA that is complexed with the ssDNA-binding protein, RPA, and to anneal complementary ssDNA complexed with RPA. Here, we report that Rad52 promotes annealing of the ssDNA strand that is displaced by DNA strand exchange by Rad51 and RPA, to a second ssDNA strand. An RPA that is recombination-deficient (RPA(rfa1-t11)) failed to support annealing, explaining its in vivo phenotype. Escherichia coli RecO and SSB proteins, which are functional homologues of Rad52 and RPA, also facilitated the same reaction, demonstrating its conserved nature. We also demonstrate that the two activities of Rad52, recruiting Rad51 and annealing DNA, are coordinated in DNA strand exchange and second ssDNA capture.
Rad51、Rad52和RPA在同源DNA重组中发挥核心作用。Rad51介导DNA链交换，这是DNA重组中的关键反应。Rad52具有两种不同的活性：将Rad51招募到与单链DNA结合蛋白RPA复合的单链（ss）DNA上，以及使与RPA复合的互补ssDNA退火。在此，我们报告Rad52促进被Rad51和RPA进行DNA链交换所置换的ssDNA链与第二条ssDNA链退火。重组缺陷型RPA（RPA(rfa1-t11)）无法支持退火，这解释了其体内表型。大肠杆菌RecO和SSB蛋白是Rad52和RPA的功能同源物，它们也促进了相同的反应，证明了其保守性。我们还证明，Rad52的两种活性，即招募Rad51和使DNA退火，在DNA链交换和第二条ssDNA捕获过程中是协调的。
