A deubiquitinase negatively regulates retro-translocation of nonubiquitinated substrates.
A deubiquitinase negatively regulates retro-translocation of nonubiquitinated substrates.
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去泛素酶负调节非泛素化底物的恢复转化。
DOI：
10.1091/mbc.e13-06-0332
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发表时间：
2013-11
影响因子：
3.3
通讯作者：
Tsai B
中科院分区：
文献类型：
--
作者：
Bernardi KM;Williams JM;Inoue T;Schultz A;Tsai B
虽然霍乱毒素是一种非泛素化的底物，可以回溯到胞浆，但这项研究确定了一种控制毒素回溯转位的脱泛素酶。内质网(ER)膜结合的E3泛素连接酶通过泛素化从内质网到达胞浆的逆转位底物，将其靶向蛋白酶体进行破坏，从而促进ER相关降解(ERAD)。最近的研究结果表明，ERAD相关的去泛素酶(DUBS)在ERAD过程中是积极的和消极的调节因子，反映了在蛋白酶体降解之前去泛素化底物的不同后果。这些观察提出了一个问题，即DUB能否控制非泛素化ERAD底物的命运。在这项研究中，我们探讨了ERAD相关的DUB，YOD1，在非泛素化霍乱毒素A1(CTA1)肽的逆转移位中的作用，这是一个关键的中毒步骤。通过结合击倒、过表达和结合的研究，我们证明了YOD1负面地控制CTA1的逆转位，可能是通过去泛素化和失活泛素化的ERAD组件来实现的，而泛素化的ERAD组件通常会促进毒素的逆转位。YOD1还可以对抗哺乳动物细胞中非糖基化的前α因子的蛋白酶体降解，这是一种假定的非泛素化酵母ERAD底物。我们的发现表明，在非泛素化底物的逆转录移位过程中，胞质DUB发挥了负功能，可能是通过作用于ERAD机制的元件。
Although cholera toxin is a nonubiquitinated substrate that undergoes retro-translocation to the cytosol, this study identifies a deubiquitinase that controls toxin retro-translocation. Endoplasmic reticulum (ER) membrane–bound E3 ubiquitin ligases promote ER-associated degradation (ERAD) by ubiquitinating a retro-translocated substrate that reaches the cytosol from the ER, targeting it to the proteasome for destruction. Recent findings implicate ERAD-associated deubiquitinases (DUBs) as positive and negative regulators during ERAD, reflecting the different consequences of deubiquitinating a substrate prior to proteasomal degradation. These observations raise the question of whether a DUB can control the fate of a nonubiquitinated ERAD substrate. In this study, we probed the role of the ERAD-associated DUB, YOD1, during retro-translocation of the nonubiquitinated cholera toxin A1 (CTA1) peptide, a critical intoxication step. Through combining knockdown, overexpression, and binding studies, we demonstrated that YOD1 negatively controls CTA1 retro-translocation, likely by deubiquitinating and inactivating ubiquitinated ERAD components that normally promote toxin retro-translocation. YOD1 also antagonizes the proteasomal degradation of nonglycosylated pro-α factor, a postulated nonubiquitinated yeast ERAD substrate, in mammalian cells. Our findings reveal that a cytosolic DUB exerts a negative function during retro-translocation of nonubiquitinated substrates, potentially by acting on elements of the ERAD machinery.