RNF126-Mediated Reubiquitination Is Required for Proteasomal Degradation of p97-Extracted Membrane Proteins
RNF126-Mediated Reubiquitination Is Required for Proteasomal Degradation of p97-Extracted Membrane Proteins
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p97 提取的膜蛋白的蛋白酶体降解需要 RNF126 介导的重泛素化
DOI：
10.1016/j.molcel.2020.06.023
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发表时间：
2020-07-16
期刊：
影响因子：
16
通讯作者：
Zhang, Zai-Rong
中科院分区：
文献类型：
--
作者：
Hu, Xianyan;Wang, Linhan;Zhang, Zai-Rong
Valosin-containing protein（VCP）/p97是一种AAA-ATP酶，能从多聚体大分子复合物和生物膜中提取多聚泛素化底物进行蛋白酶体降解。在p97介导的提取过程中，当底物穿过p97中心孔时，它在很大程度上被去泛素化。p97提取的底物如何靶向于具有很少或没有泛素的蛋白酶体尚不清楚。在这里，我们报告说，p97提取膜蛋白进行第二轮的泛素化催化的细胞溶质泛素连接酶RNF 126。RNF 126与跨膜结构域特异性分子伴侣BAG 6相互作用，后者捕获p97释放的底物。细胞中RNF 126的缺失减少了提取的膜蛋白的泛素化，减缓了它们的周转，并显著稳定了胞质溶胶中原本短暂的中间体。我们重建的p97提取，错误折叠的多跨膜蛋白与纯化的因素的再泛素化。我们的研究结果表明，p97提取的底物需要快速接合泛素连接酶-伴侣对，重建泛素信号的蛋白酶体靶向，以防止有害的积累未折叠的中间体。
Valosin-containing protein (VCP)/p97 is an AAA-ATPase that extracts polyubiquitinated substrates from multimeric macromolecular complexes and biological membranes for proteasomal degradation. During p97-mediated extraction, the substrate is largely deubiquitinated as it is threaded through the p97 central pore. How p97-extracted substrates are targeted to the proteasome with few or no ubiquitins is unknown. Here, we report that p97-extracted membrane proteins undergo a second round of ubiquitination catalyzed by the cytosolic ubiquitin ligase RNF126. RNF126 interacts with transmembrane-domain-specific chaperone BAG6, which captures p97-liberated substrates. RNF126 depletion in cells diminishes the ubiquitination of extracted membrane proteins, slows down their turnover, and dramatically stabilizes otherwise transient intermediates in the cytosol. We reconstitute the reubiquitination of a p97-extracted, misfolded multispanning membrane protein with purified factors. Our results demonstrate that p97-extracted substrates need to rapidly engage ubiquitin ligase-chaperone pairs that rebuild the ubiquitin signal for proteasome targeting to prevent harmful accumulation of unfolded intermediates.