Structure and function of the RAD51B-RAD51C-RAD51D-XRCC2 tumour suppressor.
Structure and function of the RAD51B-RAD51C-RAD51D-XRCC2 tumour suppressor.
复制标题
DOI：
10.1038/s41586-023-06179-1
复制
发表时间：
2023-07
期刊：
影响因子：
64.8
通讯作者：
West SC
中科院分区：
文献类型：
--
作者：
Greenhough LA;Liang CC;Belan O;Kunzelmann S;Maslen S;Rodrigo-Brenni MC;Anand R;Skehel M;Boulton SJ;West SC
同源重组是生命的基本过程。它是保护和重新启动断裂的复制叉，修复染色体断裂和减数分裂期间遗传物质交换所必需的。关键重组基因突变的个体，如BRCA 2（FANCD 1）或RAD 51旁系同源基因（RAD 51 B，RAD 51 C [FANCO]，RAD 51 D，XRCC 2 [FANCU]和XRCC 3）易患乳腺癌，卵巢癌和前列腺癌，或癌症易感综合征范可尼贫血。BRCA 2的产物，BRCA 2肿瘤抑制蛋白，已经被很好地表征，但是RAD 51旁系同源物的细胞功能尚不清楚。基因敲除显示生长缺陷、减少的RAD 51焦点形成、自发染色体异常、对PARP抑制剂的敏感性和复制叉缺陷，但它们在叉稳定性、DNA修复和癌症避免中的精确分子作用仍然未知。在这里，我们使用冷冻电子显微镜，AlphaFold 2建模和结构蛋白质组学来定义RAD 51 B-RAD 51 C-RAD 51 D-XRCC 2（BCDX 2）复合物的高分辨率结构，揭示RAD 51 C-RAD 51 D-XRCC 2模拟核蛋白丝内对齐的三个RAD 51原聚体，而RAD 51 B是高度动态的。生物化学和单分子分析表明，BCDX 2刺激成核和RAD 51丝，这是必要的重组DNA修复，在反应依赖于耦合的ATP酶活性的RAD 51 B和RAD 51 C的延伸。我们的研究表明，BCDX 2协调RAD 51组装在单链DNA上，用于复制叉保护和双链断裂修复，在对避免肿瘤至关重要的反应中。
Homologous recombination is a fundamental process of life. It is required for the protection and restart of broken replication forks, the repair of chromosome breaks, and the exchange of genetic material during meiosis. Individuals with mutations in key recombination genes, such as BRCA2 (FANCD1), or the RAD51 paralogs (RAD51B, RAD51C [FANCO], RAD51D, XRCC2 [FANCU] and XRCC3) are predisposed to breast, ovarian and prostate cancers, or the cancer prone syndrome Fanconi anemia. The product of BRCA2, the BRCA2 tumour suppressor protein, is well characterised, but the cellular functions of the RAD51 paralogs are unclear. Gene knockouts display growth defects, reduced RAD51 focus formation, spontaneous chromosome abnormalities, sensitivity to PARP inhibitors and replication fork defects, but their precise molecular roles in fork stability, DNA repair and cancer avoidance remain unknown. Here, we used cryo-electron microscopy, AlphaFold2 modelling and structural proteomics to define the high-resolution structure of the RAD51B-RAD51C-RAD51D-XRCC2 (BCDX2) complex, revealing that RAD51C-RAD51D-XRCC2 mimic three RAD51 protomers aligned within a nucleoprotein filament, whereas RAD51B is highly dynamic. Biochemical and single-molecule analyses showed that BCDX2 stimulates the nucleation and extension of RAD51 filaments, which are essential for recombinational DNA repair, in reactions dependent on the coupled ATPase activities of RAD51B and RAD51C. Our studies demonstrate that BCDX2 orchestrates RAD51 assembly on single-stranded DNA for replication fork protection and double strand break repair, in reactions that are critical for tumour avoidance.