DRF, IBFJ, iRCM, CEA, Fontenay-aux-Roses, France.
Université Paris-Saclay, Paris, France.
Elife. 2018 Jul 9;7:e32744. doi: 10.7554/eLife.32744.
Homology search and strand exchange mediated by Rad51 nucleoprotein filaments are key steps of the homologous recombination process. In budding yeast, Rad52 is the main mediator of Rad51 filament formation, thereby playing an essential role. The current model assumes that Rad51 filament formation requires the interaction between Rad52 and Rad51. However, we report here that Rad52 mutations that disrupt this interaction do not affect γ-ray- or HO endonuclease-induced gene conversion frequencies. In vivo and in vitro studies confirmed that Rad51 filaments formation is not affected by these mutations. Instead, we found that Rad52-Rad51 association makes Rad51 filaments toxic in Srs2-deficient cells after exposure to DNA damaging agents, independently of Rad52 role in Rad51 filament assembly. Importantly, we also demonstrated that Rad52 is essential for protecting Rad51 filaments against dissociation by the Srs2 DNA translocase. Our findings open new perspectives in the understanding of the role of Rad52 in eukaryotes.
同源搜索和链交换介导的 Rad51 核蛋白丝是同源重组过程的关键步骤。在 budding 酵母中，Rad52 是 Rad51 丝形成的主要介质，因此起着至关重要的作用。目前的模型假设 Rad51 丝的形成需要 Rad52 和 Rad51 之间的相互作用。然而，我们在这里报告说，破坏这种相互作用的 Rad52 突变不会影响 γ 射线或 HO 内切酶诱导的基因转换频率。体内和体外研究证实，这些突变并不影响 Rad51 丝的形成。相反，我们发现 Rad52-Rad51 缔合使 Rad51 丝在暴露于 DNA 损伤剂后在 Srs2 缺陷细胞中具有毒性，而与 Rad52 在 Rad51 丝组装中的作用无关。重要的是，我们还证明 Rad52 对于保护 Rad51 丝免受 Srs2 DNA 转位酶的解离是必不可少的。我们的发现为理解 Rad52 在真核生物中的作用开辟了新的视角。
