The Swi5-Sfr1 complex stimulates Rhp51/Rad51- and Dmc1-mediated DNA strand exchange in vitro
The Swi5-Sfr1 complex stimulates Rhp51/Rad51- and Dmc1-mediated DNA strand exchange in vitro
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DOI：
10.1038/nsmb1136
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发表时间：
2006-09-01
影响因子：
16.8
通讯作者：
Iwasaki, Hiroshi
中科院分区：
文献类型：
--
作者：
Haruta, Nami;Kurokawa, Yumiko;Iwasaki, Hiroshi
由 Rad51 或 Dmc1 重组酶组成的核蛋白丝（重组的核心结构）参与 ATP 依赖性 DNA 链交换。重组酶形成丝的能力通过称为“介体”的重组因子得到增强。在这里，我们发现裂殖酵母 Swi5-Sfr1 复合物（一种保守的真核蛋白质复合物）在亚化学计量浓度下刺激长 DNA 底物上由 Rhp51（裂殖酵母 Rad51 同源物）和 Dmc1 介导的链交换。两种重组酶介导的反应完全依赖于 Swi5-Sfr1、复制蛋白 A (RPA) 和 ATP，尽管 RPA 在重组酶之前与单链 DNA (ssDNA) 一起孵育时会抑制反应。 Swi5-Sfr1 复合物至少部分克服了 RPA 的抑制作用，代表了一类新型介质。值得注意的是，Swi5-Sfr1 复合物优先刺激 Rhp51 的 ssDNA 依赖性 ATP 酶活性，并增加与 ssDNA 结合的 Dmc1 量。
Nucleoprotein filaments made up of Rad51 or Dmc1 recombinases, the core structures of recombination, engage in ATP-dependent DNA-strand exchange. The ability of recombinases to form filaments is enhanced by recombination factors termed 'mediators'. Here, we show that the Schizosaccharomyces pombe Swi5-Sfr1 complex, a conserved eukaryotic protein complex, at substoichiometric concentrations stimulates strand exchange mediated by Rhp51 (the S. pombe Rad51 homolog) and Dmc1 on long DNA substrates. Reactions mediated by both recombinases are completely dependent on Swi5-Sfr1, replication protein A (RPA) and ATP, although RPA inhibits the reaction when it is incubated with single-stranded DNA (ssDNA) before the recombinase. The Swi5-Sfr1 complex overcomes, at least partly, the inhibitory effect of RPA, representing a novel class of mediator. Notably, the Swi5-Sfr1 complex preferentially stimulates the ssDNA-dependent ATPase activity of Rhp51, and it increases the amounts of Dmc1 bound to ssDNA.