Institute of Biochemical Sciences, National Taiwan University, NO. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan, Institute of Biological Chemistry, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 115, Taiwan and Department of Chemistry, National Taiwan University, NO. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan.
Nucleic Acids Res. 2014 Jan;42(1):349-58. doi: 10.1093/nar/gkt879. Epub 2013 Sep 27.
Homologous recombination catalyzed by the RAD51 recombinase eliminates deleterious DNA lesions from the genome. In the presence of ATP, RAD51 forms a nucleoprotein filament on single-stranded DNA, termed the presynaptic filament, to initiate homologous recombination-mediated DNA double-strand break repair. The SWI5-SFR1 complex stabilizes the presynaptic filament and enhances its ability to mediate the homologous DNA pairing reaction. Here we characterize the RAD51 presynaptic filament stabilization function of the SWI5-SFR1 complex using optical tweezers. Biochemical experiments reveal that SWI5-SFR1 enhances ATP hydrolysis by single-stranded DNA-bound RAD51. Importantly, we show that SWI5-SFR1 acts by facilitating the release of ADP from the presynaptic filament. Our results thus provide mechanistic understanding of the function of SWI5-SFR1 in RAD51-mediated DNA recombination.
RAD51 重组酶催化的同源重组可从基因组中消除有害的 DNA 损伤。在 ATP 的存在下，RAD51 在单链 DNA 上形成核蛋白丝，称为预联丝，以启动同源重组介导的 DNA 双链断裂修复。SWI5-SFR1 复合物稳定预联丝并增强其介导同源 DNA 配对反应的能力。在这里，我们使用光学镊子来表征 SWI5-SFR1 复合物对 RAD51 预联丝的稳定作用。生化实验表明，SWI5-SFR1 增强了 RAD51 结合的单链 DNA 的 ATP 水解。重要的是，我们表明 SWI5-SFR1 通过促进预联丝中 ADP 的释放来发挥作用。因此，我们的结果为 SWI5-SFR1 在 RAD51 介导的 DNA 重组中的功能提供了机制上的理解。
