Mutations in homologous recombination (HR) genes, including BRCA1 , BRCA2 , and the RAD51 paralog RAD51C , predispose to tumorigenesis and sensitize cancers to DNA-damaging agents and poly(ADP ribose) polymerase inhibitors. However, ∼800 missense variants of unknown significance have been identified for RAD51C alone, impairing cancer risk assessment and therapeutic strategies. Here, we interrogated >50 RAD51C missense variants, finding that mutations in residues conserved with RAD51 strongly predicted HR deficiency and disrupted interactions with other RAD51 paralogs. A cluster of mutations was identified in and around the Walker A box that led to impairments in HR, interactions with three other RAD51 paralogs, binding to single-stranded DNA, and ATP hydrolysis. We generated structural models of the two RAD51 paralog complexes containing RAD51C, RAD51B-RAD51C-RAD51D-XRCC2 and RAD51C-XRCC3. Together with our functional and biochemical analyses, the structural models predict ATP binding at the interface of RAD51C interactions with other RAD51 paralogs, similar to interactions between monomers in RAD51 filaments, and explain the failure of RAD51C variants in binding multiple paralogs. Ovarian cancer patients with variants in this cluster showed exceptionally long survival, which may be relevant to the reversion potential of the variants. This comprehensive analysis provides a framework for RAD51C variant classification. Importantly, it also provides insight into the functioning of the RAD51 paralog complexes.

中文翻译：

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肿瘤抑制基因 RAD51C 的同源重组缺陷突变簇通过癌症变异的综合分析鉴定

同源重组 (HR) 基因突变，包括BRCA1,BRCA2, 和 RAD51 平行对数RAD51C, 易患肿瘤并使癌症对 DNA 损伤剂和聚 (ADP 核糖) 聚合酶抑制剂敏感。然而，仅 RAD51C 就已经确定了约 800 个意义不明的错义变异，这会损害癌症风险评估和治疗策略。在这里，我们询问了 >50 个 RAD51C 错义变体，发现 RAD51 保守的残基突变强烈预测了 HR 缺陷并破坏了与其他 RAD51 旁系同源物的相互作用。在 Walker A 盒内和周围发现了一组突变，导致 HR 受损、与其他三个 RAD51 旁系同源物相互作用、与单链 DNA 结合以及 ATP 水解。我们生成了包含 RAD51C、RAD51B-RAD51C-RAD51D-XRCC2 和 RAD51C-XRCC3 的两个 RAD51 paralog 复合体的结构模型。连同我们的功能和生化分析，结构模型预测 RAD51C 与其他 RAD51 旁系同源相互作用界面处的 ATP 结合，类似于 RAD51 细丝中单体之间的相互作用，并解释 RAD51C 变体无法结合多个旁系同源。具有该簇中变异体的卵巢癌患者显示出特别长的生存期，这可能与变异体的逆转潜力有关。这一综合分析为 RAD51C 变体分类提供了一个框架。重要的是，它还提供了对 RAD51 paralog 复合体功能的深入了解。具有该簇中变异体的卵巢癌患者显示出特别长的生存期，这可能与变异体的逆转潜力有关。这一综合分析为 RAD51C 变体分类提供了一个框架。重要的是，它还提供了对 RAD51 paralog 复合体功能的深入了解。具有该簇中变异体的卵巢癌患者显示出特别长的生存期，这可能与变异体的逆转潜力有关。这一综合分析为 RAD51C 变体分类提供了一个框架。重要的是，它还提供了对 RAD51 paralog 复合体功能的深入了解。