Morozumi Yuichi, Takizawa Yoshimasa, Takaku Motoki, Kurumizaka Hitoshi
Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, Tokyo 162-8480, Japan.
Nucleic Acids Res. 2009 Jul;37(13):4296-307. doi: 10.1093/nar/gkp298. Epub 2009 May 15.
RAD51, a eukaryotic recombinase, catalyzes homologous-pairing and strand-exchange reactions, which are essential steps in homologous recombination and recombinational repair of double strand breaks. On the other hand, human PSF was originally identified as a component of spliceosomes, and its multiple functions in RNA processing, transcription and DNA recombination were subsequently revealed. In the present study, we found that PSF directly interacted with RAD51. PSF significantly enhanced RAD51-mediated homologous pairing and strand exchange at low RAD51 concentrations; however, in contrast, it inhibited these RAD51-mediated recombination reactions at the optimal RAD51 concentration. Deletion analyses revealed that the N-terminal region of PSF possessed the RAD51- and DNA-binding activities, but the central region containing the RNA-recognition motifs bound neither RAD51 nor DNA. These results suggest that PSF may have dual functions in homologous recombination and RNA processing through its N-terminal and central regions, respectively.
RAD51是一种真核重组酶，催化同源配对和链交换反应，这些反应是双链断裂的同源重组和重组修复中的关键步骤。另一方面，人PSF最初被鉴定为剪接体的一个组分，随后其在RNA加工、转录和DNA重组中的多种功能被揭示。在本研究中，我们发现PSF直接与RAD51相互作用。在低RAD51浓度下，PSF显著增强RAD51介导的同源配对和链交换；然而，相反的是，在最佳RAD51浓度下它抑制这些RAD51介导的重组反应。缺失分析表明，PSF的N端区域具有RAD51和DNA结合活性，但包含RNA识别基序的中央区域既不结合RAD51也不结合DNA。这些结果表明，PSF可能分别通过其N端和中央区域在同源重组和RNA加工中具有双重功能。
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