Department of Cancer Biology, Abramson Family Cancer Research Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6160, USA.
J Biol Chem. 2010 Oct 1;285(40):30971-81. doi: 10.1074/jbc.M110.135319. Epub 2010 Jul 22.
BRCC36 is a JAMM (JAB1/MPN/Mov34 metalloenzyme) domain, lysine 63-ubiquitin (K63-Ub)-specific deubiquitinating enzyme (DUB) and a member of two protein complexes: the DNA damage-responsive BRCA1-RAP80 complex, and the cytoplasmic BRCC36 isopeptidase complex (BRISC). The presence of several identical constituents in both complexes suggests common regulatory mechanisms and potential competition between K63-Ub-related signaling in cytoplasmic and nuclear compartments. Surprisingly, we discover that BRCC36 DUB activity requires different interactions within the context of each complex. Abraxas and BRCC45 were essential for BRCC36 DUB activity within the RAP80 complex, whereas KIAA0157/Abro was the only interaction required for DUB activity within the BRISC. Poh1 also required protein interactions for activity, suggesting a common regulatory mechanism for JAMM domain DUBs. Finally, BRISC deficiency enhanced formation of the BRCA1-RAP80 complex in vivo, increasing BRCA1 levels at DNA double strand breaks. These findings reveal that JAMM domain DUB activity and K63-Ub levels are regulated by multiple mechanisms within the cell.
BRCC36 是 JAMM（JAB1/MPN/Mov34 金属蛋白酶）结构域、赖氨酸 63 泛素（K63-Ub）特异性去泛素化酶（DUB），也是两个蛋白质复合物的成员：DNA 损伤反应性 BRCA1-RAP80 复合物和细胞质 BRCC36 肽基水解酶复合物（BRISC）。这两个复合物中存在几种相同的成分，这表明存在共同的调控机制，以及细胞质和核区 K63-Ub 相关信号之间可能存在竞争。令人惊讶的是，我们发现 BRCC36 DUB 活性在每个复合物中需要不同的相互作用。Abraxas 和 BRCC45 是 BRCC36 DUB 活性在 RAP80 复合物中的必需成分，而 KIAA0157/Abro 是 DUB 活性在 BRISC 中的唯一必需相互作用。Poh1 也需要蛋白相互作用才能发挥活性，这表明 JAMM 结构域 DUB 的活性受到共同的调控机制的影响。最后，BRISC 缺陷增强了体内 BRCA1-RAP80 复合物的形成，增加了 DNA 双链断裂处的 BRCA1 水平。这些发现揭示了细胞内存在多种机制来调节 JAMM 结构域 DUB 活性和 K63-Ub 水平。
