Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA.
Proc Natl Acad Sci U S A. 2011 Mar 1;108(9):3560-5. doi: 10.1073/pnas.1016454108. Epub 2011 Feb 9.
Homologous recombination is needed for meiotic chromosome segregation, genome maintenance, and tumor suppression. RAD51AP1 (RAD51 associated protein 1) has been shown to interact with and enhance the recombinase activity of RAD51. Accordingly, genetic ablation of RAD51AP1 leads to enhanced sensitivity to and also chromosome aberrations upon DNA damage, demonstrating a role for RAD51AP1 in mitotic homologous recombination. Here we show physical association of RAD51AP1 with the meiosis-specific recombinase DMC1 and a stimulatory effect of RAD51AP1 on the DMC1-mediated D-loop reaction. Mechanistic studies have revealed that RAD51AP1 enhances the ability of the DMC1 presynaptic filament to capture the duplex-DNA partner and to assemble the synaptic complex, in which the recombining DNA strands are homologously aligned. We also provide evidence that functional cooperation is dependent on complex formation between DMC1 and RAD51AP1 and that distinct epitopes in RAD51AP1 mediate interactions with RAD51 and DMC1. Finally, we show that RAD51AP1 is expressed in mouse testes, and that RAD51AP1 foci colocalize with a subset of DMC1 foci in spermatocytes. These results suggest that RAD51AP1 also serves an important role in meiotic homologous recombination.
同源重组对于减数分裂染色体分离、基因组维护和肿瘤抑制至关重要。RAD51AP1（RAD51 相关蛋白 1）已被证明与 RAD51 相互作用并增强其重组酶活性。因此，RAD51AP1 的遗传缺失会导致对 DNA 损伤的敏感性增强，并且还会导致染色体畸变，这表明 RAD51AP1 在有丝分裂同源重组中发挥作用。在这里，我们显示 RAD51AP1 与减数分裂特异性重组酶 DMC1 的物理关联，以及 RAD51AP1 对 DMC1 介导的 D 环反应的刺激作用。机制研究表明，RAD51AP1 增强了 DMC1 前突触丝捕获双链 DNA 伴侣和组装突触复合物的能力，在该复合物中，重组 DNA 链同源对齐。我们还提供了证据表明，功能合作依赖于 DMC1 和 RAD51AP1 之间的复合物形成，并且 RAD51AP1 中的不同表位介导与 RAD51 和 DMC1 的相互作用。最后，我们表明 RAD51AP1 在小鼠睾丸中表达，并且 RAD51AP1 焦点与精母细胞中 DMC1 焦点的一部分共定位。这些结果表明 RAD51AP1 也在减数分裂同源重组中发挥重要作用。
