The Lys63-deubiquitylating Enzyme BRCC36 Limits DNA Break Processing and Repair
The Lys63-deubiquitylating Enzyme BRCC36 Limits DNA Break Processing and Repair
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DOI：
10.1074/jbc.m116.731927
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发表时间：
2016-07-29
影响因子：
4.8
通讯作者：
Huen, Michael S. Y.
中科院分区：
文献类型：
--
作者：
Ng, Hoi-Man;Wei, Leizhen;Huen, Michael S. Y.
多亚基蛋白质组件为有效的细胞信号转导控制提供了集成的功能。这种蛋白质组合的一个例子是BRCA1-A大分子复合体，它偶联泛素识别和代谢，并促进细胞对DNA损伤的反应。具体地说，BRCA1-A复合体不仅识别受损染色质上的Lys(63)连接泛素(K63-Ub)加合物，而且具有K63-Ub脱泛素酶(DUB)活性。为了探索BRCA1-A DuB活性如何在DNA双链断裂(DSB)中发挥作用，我们使用RNAi和基因组编辑方法针对BRCC36，BRCC36是赋予BRCA1-A复合体DuB活性的蛋白质亚单位。有趣的是，我们发现K63-Ub Dub活性虽然对于维持大分子蛋白质组装的完整性是必不可少的，但在推动BRCA1-A复合体在DSB上的积累方面是重要的。失活的BRCC36 Dub减弱了DSB的BRCA1-A功能，导致DSB末端切除和DNA修复过度活跃。总之，我们的发现揭示了BRCC36 Dub在限制DSB处理和修复方面的关键作用，并说明了细胞如何在物理上耦合泛素识别和代谢活动，以微调DNA修复过程。
Multisubunit protein assemblies offer integrated functionalities for efficient cell signal transduction control. One example of such protein assemblies, the BRCA1-A macromolecular complex, couples ubiquitin recognition and metabolism and promotes cellular responses to DNA damage. Specifically, the BRCA1-A complex not only recognizes Lys(63)-linked ubiquitin (K63-Ub) adducts at the damaged chromatin but is endowed with K63-Ub deubiquitylase (DUB) activity. To explore how the BRCA1-A DUB activity contributes to its function at DNA double strand breaks (DSBs), we used RNAi and genome editing approaches to target BRCC36, the protein subunit that confers the BRCA1-A complex its DUB activity. Intriguingly, we found that the K63-Ub DUB activity, although dispensable for maintaining the integrity of the macromolecular protein assembly, is important in enforcing the accumulation of the BRCA1-A complex onto DSBs. Inactivating BRCC36 DUB attenuated BRCA1-A functions at DSBs and led to unrestrained DSB end resection and hyperactive DNA repair. Together, our findings uncover a pivotal role of BRCC36 DUB in limiting DSB processing and repair and illustrate how cells may physically couple ubiquitin recognition and metabolizing activities for fine tuning of DNA repair processes.