Regulation of deubiquitinating enzymes

去泛素化酶的调节

• 批准号: 8939700
• 负责人: Yihong Ye
• 金额: $ 57.06万
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8939700
• 关键词: Active Sites; Affect; Affinity; Aging; Binding; Catalytic Domain; Cells; Cellular biology; Cleaved cell; Cysteine; Cytosol; DNA Damage; Deubiquitinating Enzyme; Endoplasmic Reticulum Degradation Pathway; Enzymes; Goals; Human; In Vitro; Link; Lysine; Malignant Neoplasms; Membrane; Molecular Chaperones; Mono-S; Oxidation-Reduction; Oxidative Stress; Polyubiquitin; Post-Translational Protein Processing; Process; Proteins; Reactive Oxygen Species; Regulation; Role; Signal Transduction; Site; Transmembrane Domain; Ubiquitin; Ubiquitination; member; novel; overexpression; oxidation; oxidative DNA damage; programs; receptor; response

Protein modification by ubiquitin (Ub) is a critical regulatory process for virtually all aspects of cell biology. Substrate proteins can be modified with single ubiquitin on one (monoubiquitylation) or multiple sites (multi-ubiquitylation). Alternatively, several rounds of ubiquitination can occur on ubiquitin itself, leading to the formation of a polyubiquitin chain. Any of the seven lysines, or the amino terminus, of ubiquitin can be used to polymerize ubiquitin (Peng et al., 2003), so there are a huge number of differently linked polyubiquitin signals that can be formed. Ub signals are reversible as ubiquitin can be removed from substrates by deubiquitinating enzymes. The diverse Ub signals are recognized in cells by a myriad of receptors that carry distinct ubiquitin binding motifs recognizing mono- or polyubiquitinated substrates (Hicke et al., 2005). The mechanisms that regulate deubiquitinases in the cells are unclear. Here we characterize 34 human DUBs including 25 USP, 4 OTU, 1 Josephin and 4 UCHL subfamily members. We show that many of these enzymes are reversibly inactivated when oxidized by reactive oxygen species (ROS) in vitro and in the cell. Oxidation occurs preferentially on the catalytic cysteine, abrogating the isopeptide-cleaving activity without affecting these enzymes affinity to ubiquitin. Sensitivity to oxidative inhibition is associated with the activation of the DUBs wherein the active site cysteine is converted to a deprotonated state prone to oxidation. We further demonstrate that this redox-dependent regulation is essential for mono-ubiquitination of PCNA to occur in response to oxidative DNA damage, which initiates a DNA damage tolerance program. These findings establish a novel mechanism of DUB regulation that may be integrated with other redox-dependent signaling circuits to govern cellular adaptation to oxidative stress, a process intimately linked to aging and cancer. We recently characterized the function and regulation of USP19. We identify Hsp90 as a specific partner that binds the catalytic domain of USP19 to promote substrate association. Intriguingly, although overexpressed USP19 interacts with Derlin-1 and other ERAD machinery factors in the membrane, endogenous USP19 is mostly in the cytosol where it binds Hsp90. Accordingly, we detect neither interaction of endogenous USP19 with Derlin-1 nor significant effect on ERAD by USP19 depletion. The USP19 transmembrane domain appears to be partially stabilized in the cytosol by an interaction with its own catalytic domain, resulting in auto-inhibition of its deubiquitinating activity. These results clarify the role of USP19 in ERAD and suggest a novel DUB regulation that involves chaperone association and membrane integration.

泛素（Ub）对蛋白质的修饰是细胞生物学几乎所有方面的关键调控过程。底物蛋白可以在一个位点（单泛素化）或多个位点（多泛素化）上被单个泛素修饰。或者，几轮泛素化可以发生在泛素本身，导致多泛素链的形成。泛素的7种赖氨酸中的任何一种或氨基端都可以用于聚合泛素（Peng et al., 2003），因此可以形成大量不同连接的多泛素信号。Ub信号是可逆的，因为泛素可以通过去泛素化酶从底物中去除。不同的Ub信号在细胞中被无数的受体识别，这些受体携带不同的泛素结合基元，识别单或多泛素化底物（Hicke et al., 2005）。