1
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Kandel R, Jung J, Neal S. Proteotoxic stress and the ubiquitin proteasome system. Semin Cell Dev Biol 2024; 156:107-120. [PMID: 37734998 PMCID: PMC10807858 DOI: 10.1016/j.semcdb.2023.08.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 08/01/2023] [Accepted: 08/20/2023] [Indexed: 09/23/2023]
Abstract
The ubiquitin proteasome system maintains protein homeostasis by regulating the breakdown of misfolded proteins, thereby preventing misfolded protein aggregates. The efficient elimination is vital for preventing damage to the cell by misfolded proteins, known as proteotoxic stress. Proteotoxic stress can lead to the collapse of protein homeostasis and can alter the function of the ubiquitin proteasome system. Conversely, impairment of the ubiquitin proteasome system can also cause proteotoxic stress and disrupt protein homeostasis. This review examines two impacts of proteotoxic stress, 1) disruptions to ubiquitin homeostasis (ubiquitin stress) and 2) disruptions to proteasome homeostasis (proteasome stress). Here, we provide a mechanistic description of the relationship between proteotoxic stress and the ubiquitin proteasome system. This relationship is illustrated by findings from several protein misfolding diseases, mainly neurodegenerative diseases, as well as from basic biology discoveries from yeast to mammals. In addition, we explore the importance of the ubiquitin proteasome system in endoplasmic reticulum quality control, and how proteotoxic stress at this organelle is alleviated. Finally, we highlight how cells utilize the ubiquitin proteasome system to adapt to proteotoxic stress and how the ubiquitin proteasome system can be genetically and pharmacologically manipulated to maintain protein homeostasis.
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Affiliation(s)
- Rachel Kandel
- School of Biological Sciences, Department of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, United States
| | - Jasmine Jung
- School of Biological Sciences, Department of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, United States
| | - Sonya Neal
- School of Biological Sciences, Department of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, United States; Howard Hughes Medical Institute, Chevy Chase, MD, USA.
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2
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Lee H, Kim S, Lee D. The versatility of the proteasome in gene expression and silencing: Unraveling proteolytic and non-proteolytic functions. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2023; 1866:194978. [PMID: 37633648 DOI: 10.1016/j.bbagrm.2023.194978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 08/02/2023] [Accepted: 08/21/2023] [Indexed: 08/28/2023]
Abstract
The 26S proteasome consists of a 20S core particle and a 19S regulatory particle and critically regulates gene expression and silencing through both proteolytic and non-proteolytic functions. The 20S core particle mediates proteolysis, while the 19S regulatory particle performs non-proteolytic functions. The proteasome plays a role in regulating gene expression in euchromatin by modifying histones, activating transcription, initiating and terminating transcription, mRNA export, and maintaining transcriptome integrity. In gene silencing, the proteasome modulates the heterochromatin formation, spreading, and subtelomere silencing by degrading specific proteins and interacting with anti-silencing factors such as Epe1, Mst2, and Leo1. This review discusses the proteolytic and non-proteolytic functions of the proteasome in regulating gene expression and gene silencing-related heterochromatin formation. This article is part of a special issue on the regulation of gene expression and genome integrity by the ubiquitin-proteasome system.
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Affiliation(s)
- Hyesu Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea
| | - Sungwook Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea
| | - Daeyoup Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea.
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3
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Betancourt D, Lawal T, Tomko RJ. Wiggle and Shake: Managing and Exploiting Conformational Dynamics during Proteasome Biogenesis. Biomolecules 2023; 13:1223. [PMID: 37627288 PMCID: PMC10452565 DOI: 10.3390/biom13081223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 08/01/2023] [Accepted: 08/03/2023] [Indexed: 08/27/2023] Open
Abstract
The 26S proteasome is the largest and most complicated protease known, and changes to proteasome assembly or function contribute to numerous human diseases. Assembly of the 26S proteasome from its ~66 individual polypeptide subunits is a highly orchestrated process requiring the concerted actions of both intrinsic elements of proteasome subunits, as well as assistance by extrinsic, dedicated proteasome assembly chaperones. With the advent of near-atomic resolution cryo-electron microscopy, it has become evident that the proteasome is a highly dynamic machine, undergoing numerous conformational changes in response to ligand binding and during the proteolytic cycle. In contrast, an appreciation of the role of conformational dynamics during the biogenesis of the proteasome has only recently begun to emerge. Herein, we review our current knowledge of proteasome assembly, with a particular focus on how conformational dynamics guide particular proteasome biogenesis events. Furthermore, we highlight key emerging questions in this rapidly expanding area.
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Affiliation(s)
| | | | - Robert J. Tomko
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL 32306, USA; (D.B.); (T.L.)
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4
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Brockmann F, Catone N, Wünsch C, Offensperger F, Scheffner M, Schmidtke G, Aichem A. FAT10 and NUB1L cooperate to activate the 26S proteasome. Life Sci Alliance 2023; 6:e202201463. [PMID: 37188463 PMCID: PMC10185811 DOI: 10.26508/lsa.202201463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 05/02/2023] [Accepted: 05/03/2023] [Indexed: 05/17/2023] Open
Abstract
The interaction of the 19S regulatory particle of the 26S proteasome with ubiquitylated proteins leads to gate opening of the 20S core particle and increases its proteolytic activity by binding of the ubiquitin chain to the inhibitory deubiquitylation enzyme USP14 on the 19S regulatory subunit RPN1. Covalent modification of proteins with the cytokine inducible ubiquitin-like modifier FAT10 is an alternative signal for proteasomal degradation. Here, we report that FAT10 and its interaction partner NUB1L facilitate the gate opening of the 20S proteasome in an ubiquitin- and USP14-independent manner. We also show that FAT10 is capable to activate all peptidolytic activities of the 26S proteasome, however only together with NUB1L, by binding to the UBA domains of NUB1L and thereby interfering with NUB1L dimerization. The binding of FAT10 to NUB1L leads to an increased affinity of NUB1L for the subunit RPN1. In conclusion, the herein described cooperation of FAT10 and NUB1L is a substrate-induced mechanism to activate the 26S proteasome.
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Affiliation(s)
- Florian Brockmann
- Division of Immunology, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Nicola Catone
- Biotechnology Institute Thurgauhttps://ror.org/0546hnb39 at the University of Konstanz, Kreuzlingen, Switzerland
| | - Christine Wünsch
- Division of Immunology, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Fabian Offensperger
- Division of Biochemistry, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Martin Scheffner
- Division of Biochemistry, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Gunter Schmidtke
- Division of Immunology, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Annette Aichem
- Division of Immunology, Department of Biology, University of Konstanz, Konstanz, Germany
- Biotechnology Institute Thurgauhttps://ror.org/0546hnb39 at the University of Konstanz, Kreuzlingen, Switzerland
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5
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Osei-Amponsa V, Walters KJ. Proteasome substrate receptors and their therapeutic potential. Trends Biochem Sci 2022; 47:950-964. [PMID: 35817651 PMCID: PMC9588529 DOI: 10.1016/j.tibs.2022.06.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 06/02/2022] [Accepted: 06/14/2022] [Indexed: 11/22/2022]
Abstract
The ubiquitin-proteasome system (UPS) is critical for protein quality control and regulating protein lifespans. Following ubiquitination, UPS substrates bind multidomain receptors that, in addition to ubiquitin-binding sites, contain functional domains that bind to deubiquitinating enzymes (DUBs) or the E3 ligase E6AP/UBE3A. We provide an overview of the proteasome, focusing on its receptors and DUBs. We highlight the key role of dynamics and importance of the substrate receptors having domains for both binding and processing ubiquitin chains. The UPS is rich with therapeutic opportunities, with proteasome inhibitors used clinically and ongoing development of small molecule proteolysis targeting chimeras (PROTACs) for the degradation of disease-associated proteins. We discuss the therapeutic potential of proteasome receptors, including hRpn13, for which PROTACs have been developed.
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Affiliation(s)
- Vasty Osei-Amponsa
- Protein Processing Section, Center for Structural Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA
| | - Kylie J Walters
- Protein Processing Section, Center for Structural Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA.
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6
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Schnell HM, Hanna J. DUB-le vision: snapshots of the proteasome during substrate processing. Trends Biochem Sci 2022; 47:903-905. [PMID: 35963751 PMCID: PMC10879984 DOI: 10.1016/j.tibs.2022.07.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 07/21/2022] [Accepted: 07/26/2022] [Indexed: 11/22/2022]
Abstract
Covalent modification by the small protein ubiquitin can target proteins for destruction by the proteasome, but the ubiquitin signal itself is recycled. Surprisingly, proteasomes contain three different deubiquitinating enzymes (DUBs). Recent work by Zhang and Zou et al. reveals how one of these enzymes, Usp14, regulates, and is regulated by, the proteasome.
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Affiliation(s)
- Helena M Schnell
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA
| | - John Hanna
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA.
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7
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Zhao J, Guo J, Wang Y, Ma Q, Shi Y, Cheng F, Lu Q, Fu W, Ouyang G, Zhang J, Xu Q, Hu X. Research Progress of DUB Enzyme in Hepatocellular Carcinoma. Front Oncol 2022; 12:920287. [PMID: 35875077 PMCID: PMC9303014 DOI: 10.3389/fonc.2022.920287] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 05/24/2022] [Indexed: 11/13/2022] Open
Abstract
According to GLOBOCAN 2021 cancer incidence and mortality statistics compiled by the International Agency for Research on Cancer, hepatocellular carcinoma (HCC) is the most common malignancy in the human liver and one of the leading causes of cancer death worldwide. Although there have been great advances in the treatment of HCC, such as regofenib, sorafenib, and lomvatinib, which have been developed and approved for the clinical treatment of advanced or metastatic HCC. However, they only prolong survival by a few months, and patients with advanced liver cancer are susceptible to tumor invasion metastasis and drug resistance. Ubiquitination modification is a type of post-translational modification of proteins. It can affect the physiological activity of cells by regulating the localization, stability and activity of proteins, such as: gene transcription, DNA damage signaling and other pathways. The reversible process of ubiquitination is called de-ubiquitination: it is the process of re-releasing ubiquitinated substrates with the participation of de-ubiquitinases (DUBs) and other active substances. There is growing evidence that many dysregulations of DUBs are associated with tumorigenesis. Although dysregulation of deuquitinase function is often found in HCC and other cancers, The mechanisms of action of many DUBs in HCC have not been elucidated. In this review, we focused on several deubiquitinases (DUBs) associated with hepatocellular carcinoma, including their structure, function, and relationship to hepatocellular carcinoma. hepatocellular carcinoma was highlighted, as well as the latest research reports. Among them, we focus on the USP family and OTU family which are more studied in the HCC. In addition, we discussed the prospects and significance of targeting DUBs as a new strategy for the treatment of hepatocellular carcinoma. It also briefly summarizes the research progress of some DUB-related small molecule inhibitors and their clinical application significance as a treatment for HCC in the future.
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Affiliation(s)
- Jie Zhao
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
- Laboratory of Tumor Molecular Diagnosis and Individualized Medicine of Zhejiang Province, Zhejiang Provincial People’s Hospital, Affiliated People’s Hospital, Hangzhou Medical College, Hangzhou, China
| | - Jinhui Guo
- Qingdao Medical College, Qingdao University, Qingdao, China
| | - Yanan Wang
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Qiancheng Ma
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Yu Shi
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Feng Cheng
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Qiliang Lu
- Qingdao Medical College, Qingdao University, Qingdao, China
| | - Wen Fu
- Qingdao Medical College, Qingdao University, Qingdao, China
| | | | - Ji Zhang
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Qiuran Xu
- Laboratory of Tumor Molecular Diagnosis and Individualized Medicine of Zhejiang Province, Zhejiang Provincial People’s Hospital, Affiliated People’s Hospital, Hangzhou Medical College, Hangzhou, China
- *Correspondence: Xiaoge Hu, ; Qiuran Xu,
| | - Xiaoge Hu
- Department of Hepatobiliary and Pancreatic Surgery, Zhejiang Provincial People’s Hospital, Affiliated People’s Hospital, Hangzhou Medical CollegeHangzhou, China
- The Key Laboratory of Tumor Molecular Diagnosis and Individualized Medicine of Zhejiang Province, Zhejiang Provincial People’s Hospital, Affiliated People’s Hospital, Hangzhou Medical College, Hangzhou, China
- *Correspondence: Xiaoge Hu, ; Qiuran Xu,
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8
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Enenkel C, Kang RW, Wilfling F, Ernst OP. Intracellular localization of the proteasome in response to stress conditions. J Biol Chem 2022; 298:102083. [PMID: 35636514 PMCID: PMC9218506 DOI: 10.1016/j.jbc.2022.102083] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 05/13/2022] [Accepted: 05/16/2022] [Indexed: 12/15/2022] Open
Abstract
The ubiquitin–proteasome system fulfills an essential role in regulating protein homeostasis by spatially and temporally controlling proteolysis in an ATP- and ubiquitin-dependent manner. However, the localization of proteasomes is highly variable under diverse cellular conditions. In yeast, newly synthesized proteasomes are primarily localized to the nucleus during cell proliferation. Yeast proteasomes are transported into the nucleus through the nuclear pore either as immature subcomplexes or as mature enzymes via adapter proteins Sts1 and Blm10, while in mammalian cells, postmitotic uptake of proteasomes into the nucleus is mediated by AKIRIN2, an adapter protein essentially required for nuclear protein degradation. Stressful growth conditions and the reversible halt of proliferation, that is quiescence, are associated with a decline in ATP and the reorganization of proteasome localization. Cellular stress leads to proteasome accumulation in membraneless granules either in the nucleus or in the cytoplasm. In quiescence, yeast proteasomes are sequestered in an ubiquitin-dependent manner into motile and reversible proteasome storage granules in the cytoplasm. In cancer cells, upon amino acid deprivation, heat shock, osmotic stress, oxidative stress, or the inhibition of either proteasome activity or nuclear export, reversible proteasome foci containing polyubiquitinated substrates are formed by liquid–liquid phase separation in the nucleus. In this review, we summarize recent literature revealing new links between nuclear transport, ubiquitin signaling, and the intracellular organization of proteasomes during cellular stress conditions.
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Affiliation(s)
- Cordula Enenkel
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
| | - Ryu Won Kang
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Florian Wilfling
- Mechanisms of Cellular Quality Control, Max-Planck-Institute of Biophysics, Frankfurt, Germany
| | - Oliver P Ernst
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada; Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
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9
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USP14-regulated allostery of the human proteasome by time-resolved cryo-EM. Nature 2022; 605:567-574. [PMID: 35477760 PMCID: PMC9117149 DOI: 10.1038/s41586-022-04671-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 03/22/2022] [Indexed: 01/19/2023]
Abstract
Proteasomal degradation of ubiquitylated proteins is tightly regulated at multiple levels1-3. A primary regulatory checkpoint is the removal of ubiquitin chains from substrates by the deubiquitylating enzyme ubiquitin-specific protease 14 (USP14), which reversibly binds the proteasome and confers the ability to edit and reject substrates. How USP14 is activated and regulates proteasome function remain unknown4-7. Here we present high-resolution cryo-electron microscopy structures of human USP14 in complex with the 26S proteasome in 13 distinct conformational states captured during degradation of polyubiquitylated proteins. Time-resolved cryo-electron microscopy analysis of the conformational continuum revealed two parallel pathways of proteasome state transitions induced by USP14, and captured transient conversion of substrate-engaged intermediates into substrate-inhibited intermediates. On the substrate-engaged pathway, ubiquitin-dependent activation of USP14 allosterically reprograms the conformational landscape of the AAA-ATPase motor and stimulates opening of the core particle gate8-10, enabling observation of a near-complete cycle of asymmetric ATP hydrolysis around the ATPase ring during processive substrate unfolding. Dynamic USP14-ATPase interactions decouple the ATPase activity from RPN11-catalysed deubiquitylation11-13 and kinetically introduce three regulatory checkpoints on the proteasome, at the steps of ubiquitin recognition, substrate translocation initiation and ubiquitin chain recycling. These findings provide insights into the complete functional cycle of the USP14-regulated proteasome and establish mechanistic foundations for the discovery of USP14-targeted therapies.
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10
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van der Wal L, Bezstarosti K, Demmers JAA. A ubiquitinome analysis to study the functional roles of the proteasome associated deubiquitinating enzymes USP14 and UCH37. J Proteomics 2022; 262:104592. [PMID: 35489684 DOI: 10.1016/j.jprot.2022.104592] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 04/05/2022] [Accepted: 04/17/2022] [Indexed: 12/12/2022]
Abstract
The removal of (poly)ubiquitin chains at the proteasome is a key step in the protein degradation pathway that determines which proteins are degraded and ultimately decides cell fate. Three different deubiquitinating enzymes (DUBs) are associated to the human proteasome, PSMD14 (RPN11), USP14 and UCH37 (UCHL5). However, the functional roles and specificities of these proteasomal DUBs remain elusive. To reveal the specificities of proteasome associated DUBs, we used SILAC based quantitative ubiquitinomics to study the effects of CRISPR-Cas9 based knockout of each of these DUBs on the dynamic cellular ubiquitinome. We observed distinct effects on the global ubiquitinome upon removal of either USP14 or UCH37, while the simultaneous removal of both DUBs suggested less functional redundancy than previously anticipated. We also investigated whether the small molecule inhibitor b-AP15 has the potential to specifically target USP14 and UCH37 by comparing treatment of wild-type versus USP14/UCH37 double-knockout cells with this drug. Strikingly, broad and severe off-target effects were observed, questioning the alleged specificity of this inhibitor. In conclusion, this work presents novel insights into the function of proteasome associated DUBs and illustrates the power of in-depth ubiquitinomics for screening the activity of DUBs and of DUB modulating compounds. SIGNIFICANCE Introduction: The removal of (poly)ubiquitin chains at the proteasome is a key step in the protein degradation pathway that determines which proteins are degraded and ultimately decides cell fate. Three different deubiquitinating enzymes (DUBs) are associated to the human proteasome, PSMD14/RPN11, USP14 and UCH37/UCHL5. However, the functional roles and specificities of these proteasomal DUBs remains elusive. MATERIALS & METHODS We have applied a SILAC based quantitative ubiquitinomics to study the effects of CRISPR-Cas9 based knockout of each of these DUBs on the dynamic cellular ubiquitinome. Also, we have studied the function of the small molecule inhibitor b-AP15, which has the potential to specifically target USP14 and UCH37. RESULTS We report distinct effects on the ubiquitinome and the ability of the proteasome to clear proteins upon removal of either USP14 or UCH37, while the simultaneous removal of both DUBs suggests less redundancy than previously anticipated. In addition, broad and severe off-target effects were observed for b-AP15, questioning the alleged specificity of this inhibitor. CONCLUSIONS This work presents novel insights into the function of proteasome associated DUBs and illustrates the power of in-depth ubiquitinomics for screening the activity of DUBs and of DUB modulating compounds.
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Affiliation(s)
- Lennart van der Wal
- Proteomics Center, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Karel Bezstarosti
- Proteomics Center, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Jeroen A A Demmers
- Proteomics Center, Erasmus University Medical Center, Rotterdam, the Netherlands.
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11
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Hung KYS, Klumpe S, Eisele MR, Elsasser S, Tian G, Sun S, Moroco JA, Cheng TC, Joshi T, Seibel T, Van Dalen D, Feng XH, Lu Y, Ovaa H, Engen JR, Lee BH, Rudack T, Sakata E, Finley D. Allosteric control of Ubp6 and the proteasome via a bidirectional switch. Nat Commun 2022; 13:838. [PMID: 35149681 PMCID: PMC8837689 DOI: 10.1038/s41467-022-28186-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Accepted: 01/10/2022] [Indexed: 11/09/2022] Open
Abstract
The proteasome recognizes ubiquitinated proteins and can also edit ubiquitin marks, allowing substrates to be rejected based on ubiquitin chain topology. In yeast, editing is mediated by deubiquitinating enzyme Ubp6. The proteasome activates Ubp6, whereas Ubp6 inhibits the proteasome through deubiquitination and a noncatalytic effect. Here, we report cryo-EM structures of the proteasome bound to Ubp6, based on which we identify mutants in Ubp6 and proteasome subunit Rpt1 that abrogate Ubp6 activation. The Ubp6 mutations define a conserved region that we term the ILR element. The ILR is found within the BL1 loop, which obstructs the catalytic groove in free Ubp6. Rpt1-ILR interaction opens the groove by rearranging not only BL1 but also a previously undescribed network of three interconnected active-site-blocking loops. Ubp6 activation and noncatalytic proteasome inhibition are linked in that they are eliminated by the same mutations. Ubp6 and ubiquitin together drive proteasomes into a unique conformation associated with proteasome inhibition. Thus, a multicomponent allosteric switch exerts simultaneous control over both Ubp6 and the proteasome.
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Affiliation(s)
| | - Sven Klumpe
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Markus R Eisele
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Suzanne Elsasser
- Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Geng Tian
- Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Shuangwu Sun
- Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA.,Life Sciences Institute (LSI), Zhejiang University, Hangzhou, 310058, China
| | - Jamie A Moroco
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, 02115, USA
| | - Tat Cheung Cheng
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany.,Institute for Auditory Neuroscience, University Medical Center Göttingen, 37077, Göttingen, Germany
| | - Tapan Joshi
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Timo Seibel
- Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Duco Van Dalen
- Leiden University Medical Center, Einthovenweg 20, 2333, Leiden, ZC, the Netherlands
| | - Xin-Hua Feng
- Life Sciences Institute (LSI), Zhejiang University, Hangzhou, 310058, China
| | - Ying Lu
- Department of Systems Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Huib Ovaa
- Leiden University Medical Center, Einthovenweg 20, 2333, Leiden, ZC, the Netherlands
| | - John R Engen
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, 02115, USA
| | - Byung-Hoon Lee
- Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, 42988, Korea.
| | - Till Rudack
- Biospectroscopy, Center for Protein Diagnostics (PRODI), Ruhr University Bochum, 44801, Bochum, Germany. .,Department of Biophysics, Ruhr University Bochum, 44801, Bochum, Germany.
| | - Eri Sakata
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany. .,Institute for Auditory Neuroscience, University Medical Center Göttingen, 37077, Göttingen, Germany. .,Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells (MBExC), University of Goettingen, 37073, Göttingen, Germany.
| | - Daniel Finley
- Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA.
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12
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Wang F, Ning S, Yu B, Wang Y. USP14: Structure, Function, and Target Inhibition. Front Pharmacol 2022; 12:801328. [PMID: 35069211 PMCID: PMC8766727 DOI: 10.3389/fphar.2021.801328] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 12/13/2021] [Indexed: 12/24/2022] Open
Abstract
Ubiquitin-specific protease 14 (USP14), a deubiquitinating enzyme (DUB), is associated with proteasomes and exerts a dual function in regulating protein degradation. USP14 protects protein substrates from degradation by removing ubiquitin chains from proteasome-bound substrates, whereas promotes protein degradation by activating the proteasome. Increasing evidence have shown that USP14 is involved in several canonical signaling pathways, correlating with cancer, neurodegenerative diseases, autophagy, immune responses, and viral infections. The activity of USP14 is tightly regulated to ensure its function in various cellular processes. Structural studies have demonstrated that free USP14 exists in an autoinhibited state with two surface loops, BL1 and BL2, partially hovering above and blocking the active site cleft binding to the C-terminus of ubiquitin. Hence, both proteasome-bound and phosphorylated forms of USP14 require the induction of conformational changes in the BL2 loop to activate its deubiquitinating function. Due to its intriguing roles in the stabilization of disease-causing proteins and oncology targets, USP14 has garnered widespread interest as a therapeutic target. In recent years, significant progress has been made on identifying inhibitors targeting USP14, despite the complexity and challenges in improving their selectivity and affinity for USP14. In particular, the crystal structures of USP14 complexed with IU1-series inhibitors revealed the underlying allosteric regulatory mechanism and enabled the further design of potent inhibitors. In this review, we summarize the current knowledge regarding the structure, regulation, pathophysiological function, and selective inhibition of USP14, including disease associations and inhibitor development.
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Affiliation(s)
| | | | | | - Yanfeng Wang
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, China
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13
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George DE, Tepe JJ. Advances in Proteasome Enhancement by Small Molecules. Biomolecules 2021; 11:1789. [PMID: 34944433 PMCID: PMC8699248 DOI: 10.3390/biom11121789] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/23/2021] [Accepted: 11/26/2021] [Indexed: 01/11/2023] Open
Abstract
The proteasome system is a large and complex molecular machinery responsible for the degradation of misfolded, damaged, and redundant cellular proteins. When proteasome function is impaired, unwanted proteins accumulate, which can lead to several diseases including age-related and neurodegenerative diseases. Enhancing proteasome-mediated substrate degradation with small molecules may therefore be a valuable strategy for the treatment of various neurodegenerative diseases such as Parkinson's, Alzheimer's, and Huntington's diseases. In this review, we discuss the structure of proteasome and how proteasome's proteolytic activity is associated with aging and various neurodegenerative diseases. We also summarize various classes of compounds that are capable of enhancing, directly or indirectly, proteasome-mediated protein degradation.
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Affiliation(s)
| | - Jetze J. Tepe
- Department of Chemistry and Pharmacology & Toxicology, Michigan State University, East Lansing, MI 48824, USA;
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14
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Chen X, Htet ZM, López-Alfonzo E, Martin A, Walters KJ. Proteasome interaction with ubiquitinated substrates: from mechanisms to therapies. FEBS J 2021; 288:5231-5251. [PMID: 33211406 PMCID: PMC8131406 DOI: 10.1111/febs.15638] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 11/10/2020] [Accepted: 11/17/2020] [Indexed: 12/11/2022]
Abstract
The 26S proteasome is responsible for regulated proteolysis in eukaryotic cells. Its substrates are diverse in structure, function, sequence length, and amino acid composition, and are targeted to the proteasome by post-translational modification with ubiquitin. Ubiquitination occurs through a complex enzymatic cascade and can also signal for other cellular events, unrelated to proteasome-catalyzed degradation. Like other post-translational protein modifications, ubiquitination is reversible, with ubiquitin chain hydrolysis catalyzed by the action of deubiquitinating enzymes (DUBs), ~ 90 of which exist in humans and allow for temporal events and dynamic ubiquitin-chain remodeling. DUBs have been known for decades to be an integral part of the proteasome, as deubiquitination is coupled to substrate unfolding and translocation into the internal degradation chamber. Moreover, the proteasome also binds several ubiquitinating enzymes and shuttle factors that recruit ubiquitinated substrates. The role of this intricate machinery and how ubiquitinated substrates interact with proteasomes remains an area of active investigation. Here, we review what has been learned about the mechanisms used by the proteasome to bind ubiquitinated substrates, substrate shuttle factors, ubiquitination machinery, and DUBs. We also discuss many open questions that require further study or the development of innovative approaches to be answered. Finally, we address the promise of expanded therapeutic targeting that could benefit from such new discoveries.
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Affiliation(s)
- Xiang Chen
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | - Zaw Min Htet
- Department of Molecular and Cell Biology, California Institute for Quantitative Biosciences, University of California at Berkeley, CA, USA
| | - Erika López-Alfonzo
- Department of Molecular and Cell Biology, California Institute for Quantitative Biosciences, University of California at Berkeley, CA, USA
| | - Andreas Martin
- Department of Molecular and Cell Biology, California Institute for Quantitative Biosciences, University of California at Berkeley, CA, USA
- Howard Hughes Medical Institute, University of California at Berkeley, CA, USA
| | - Kylie J Walters
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
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15
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Small-Molecule Inhibitors Targeting Proteasome-Associated Deubiquitinases. Int J Mol Sci 2021; 22:ijms22126213. [PMID: 34207520 PMCID: PMC8226605 DOI: 10.3390/ijms22126213] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 06/02/2021] [Accepted: 06/05/2021] [Indexed: 02/06/2023] Open
Abstract
The 26S proteasome is the principal protease for regulated intracellular proteolysis. This multi-subunit complex is also pivotal for clearance of harmful proteins that are produced throughout the lifetime of eukaryotes. Recent structural and kinetic studies have revealed a multitude of conformational states of the proteasome in substrate-free and substrate-engaged forms. These conformational transitions demonstrate that proteasome is a highly dynamic machinery during substrate processing that can be also controlled by a number of proteasome-associated factors. Essentially, three distinct family of deubiquitinases–USP14, RPN11, and UCH37–are associated with the 19S regulatory particle of human proteasome. USP14 and UCH37 are capable of editing ubiquitin conjugates during the process of their dynamic engagement into the proteasome prior to the catalytic commitment. In contrast, RPN11-mediated deubiquitination is directly coupled to substrate degradation by sensing the proteasome’s conformational switch into the commitment steps. Therefore, proteasome-bound deubiquitinases are likely to tailor the degradation events in accordance with substrate processing steps and for dynamic proteolysis outcomes. Recent chemical screening efforts have yielded highly selective small-molecule inhibitors for targeting proteasomal deubiquitinases, such as USP14 and RPN11. USP14 inhibitors, IU1 and its progeny, were found to promote the degradation of a subset of substrates probably by overriding USP14-imposed checkpoint on the proteasome. On the other hand, capzimin, a RPN11 inhibitor, stabilized the proteasome substrates and showed the anti-proliferative effects on cancer cells. It is highly conceivable that these specific inhibitors will aid to dissect the role of each deubiquitinase on the proteasome. Moreover, customized targeting of proteasome-associated deubiquitinases may also provide versatile therapeutic strategies for induced or repressed protein degradation depending on proteolytic demand and cellular context.
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16
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Mechanisms That Activate 26S Proteasomes and Enhance Protein Degradation. Biomolecules 2021; 11:biom11060779. [PMID: 34067263 PMCID: PMC8224753 DOI: 10.3390/biom11060779] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 05/11/2021] [Accepted: 05/12/2021] [Indexed: 02/07/2023] Open
Abstract
Although ubiquitination is widely assumed to be the only regulated step in the ubiquitin–proteasome pathway, recent studies have demonstrated several important mechanisms that regulate the activities of the 26S proteasome. Most proteasomes in cells are inactive but, upon binding a ubiquitinated substrate, become activated by a two-step mechanism requiring an association of the ubiquitin chain with Usp14 and then a loosely folded protein domain with the ATPases. The initial activation step is signaled by Usp14’s UBL domain, and many UBL-domain-containing proteins (e.g., Rad23, Parkin) also activate the proteasome. ZFAND5 is a distinct type of activator that binds ubiquitin conjugates and the proteasome and stimulates proteolysis during muscle atrophy. The proteasome’s activities are also regulated through subunit phosphorylation. Agents that raise cAMP and activate PKA stimulate within minutes Rpn6 phosphorylation and enhance the selective degradation of short-lived proteins. Likewise, hormones, fasting, and exercise, which raise cAMP, activate proteasomes and proteolysis in target tissues. Agents that raise cGMP and activate PKG also stimulate 26S activities but modify different subunit(s) and stimulate also the degradation of long-lived cell proteins. Both kinases enhance the selective degradation of aggregation-prone proteins that cause neurodegenerative diseases. These new mechanisms regulating proteolysis thus have clear physiological importance and therapeutic potential.
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17
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Gutierrez C, Salituro LJ, Yu C, Wang X, DePeter SF, Rychnovsky SD, Huang L. Enabling Photoactivated Cross-Linking Mass Spectrometric Analysis of Protein Complexes by Novel MS-Cleavable Cross-Linkers. Mol Cell Proteomics 2021; 20:100084. [PMID: 33915260 PMCID: PMC8214149 DOI: 10.1016/j.mcpro.2021.100084] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 04/02/2021] [Accepted: 04/21/2021] [Indexed: 12/15/2022] Open
Abstract
Cross-linking mass spectrometry (XL-MS) is a powerful tool for studying protein-protein interactions and elucidating architectures of protein complexes. While residue-specific XL-MS studies have been very successful, accessibility of interaction regions nontargetable by specific chemistries remain difficult. Photochemistry has shown great potential in capturing those regions because of nonspecific reactivity, but low yields and high complexities of photocross-linked products have hindered their identification, limiting current studies predominantly to single proteins. Here, we describe the development of three novel MS-cleavable heterobifunctional cross-linkers, namely SDASO (Succinimidyl diazirine sulfoxide), to enable fast and accurate identification of photocross-linked peptides by MSn. The MSn-based workflow allowed SDASO XL-MS analysis of the yeast 26S proteasome, demonstrating the feasibility of photocross-linking of large protein complexes for the first time. Comparative analyses have revealed that SDASO cross-linking is robust and captures interactions complementary to residue-specific reagents, providing the foundation for future applications of photocross-linking in complex XL-MS studies.
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Affiliation(s)
- Craig Gutierrez
- Department of Physiology and Biophysics, University of California, Irvine, California, USA
| | - Leah J Salituro
- Department of Chemistry, University of California, Irvine, California, USA
| | - Clinton Yu
- Department of Physiology and Biophysics, University of California, Irvine, California, USA
| | - Xiaorong Wang
- Department of Physiology and Biophysics, University of California, Irvine, California, USA
| | - Sadie F DePeter
- Department of Chemistry, University of California, Irvine, California, USA
| | - Scott D Rychnovsky
- Department of Chemistry, University of California, Irvine, California, USA
| | - Lan Huang
- Department of Physiology and Biophysics, University of California, Irvine, California, USA.
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Radzinski M, Oppenheim T, Metanis N, Reichmann D. The Cys Sense: Thiol Redox Switches Mediate Life Cycles of Cellular Proteins. Biomolecules 2021; 11:469. [PMID: 33809923 PMCID: PMC8004198 DOI: 10.3390/biom11030469] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Revised: 03/15/2021] [Accepted: 03/16/2021] [Indexed: 12/14/2022] Open
Abstract
Protein homeostasis is an essential component of proper cellular function; however, sustaining protein health is a challenging task, especially during the aerobic lifestyle. Natural cellular oxidants may be involved in cell signaling and antibacterial defense; however, imbalanced levels can lead to protein misfolding, cell damage, and death. This merges together the processes of protein homeostasis and redox regulation. At the heart of this process are redox-regulated proteins or thiol-based switches, which carefully mediate various steps of protein homeostasis across folding, localization, quality control, and degradation pathways. In this review, we discuss the "redox code" of the proteostasis network, which shapes protein health during cell growth and aging. We describe the sources and types of thiol modifications and elaborate on diverse strategies of evolving antioxidant proteins in proteostasis networks during oxidative stress conditions. We also highlight the involvement of cysteines in protein degradation across varying levels, showcasing the importance of cysteine thiols in proteostasis at large. The individual examples and mechanisms raised open the door for extensive future research exploring the interplay between the redox and protein homeostasis systems. Understanding this interplay will enable us to re-write the redox code of cells and use it for biotechnological and therapeutic purposes.
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Affiliation(s)
- Meytal Radzinski
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Safra Campus Givat Ram, The Hebrew University of Jerusalem, Jerusalem 91904, Israel; (M.R.); (T.O.)
| | - Tal Oppenheim
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Safra Campus Givat Ram, The Hebrew University of Jerusalem, Jerusalem 91904, Israel; (M.R.); (T.O.)
| | - Norman Metanis
- Institute of Chemistry, Safra Campus Givat Ram, The Hebrew University of Jerusalem, Jerusalem 91904, Israel;
| | - Dana Reichmann
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Safra Campus Givat Ram, The Hebrew University of Jerusalem, Jerusalem 91904, Israel; (M.R.); (T.O.)
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19
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Proteasome in action: substrate degradation by the 26S proteasome. Biochem Soc Trans 2021; 49:629-644. [PMID: 33729481 PMCID: PMC8106498 DOI: 10.1042/bst20200382] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 02/22/2021] [Accepted: 02/25/2021] [Indexed: 12/16/2022]
Abstract
Ubiquitination is the major criteria for the recognition of a substrate-protein by the 26S proteasome. Additionally, a disordered segment on the substrate — either intrinsic or induced — is critical for proteasome engagement. The proteasome is geared to interact with both of these substrate features and prepare it for degradation. To facilitate substrate accessibility, resting proteasomes are characterised by a peripheral distribution of ubiquitin receptors on the 19S regulatory particle (RP) and a wide-open lateral surface on the ATPase ring. In this substrate accepting state, the internal channel through the ATPase ring is discontinuous, thereby obstructing translocation of potential substrates. The binding of the conjugated ubiquitin to the ubiquitin receptors leads to contraction of the 19S RP. Next, the ATPases engage the substrate at a disordered segment, energetically unravel the polypeptide and translocate it towards the 20S catalytic core (CP). In this substrate engaged state, Rpn11 is repositioned at the pore of the ATPase channel to remove remaining ubiquitin modifications and accelerate translocation. C-termini of five of the six ATPases insert into corresponding lysine-pockets on the 20S α-ring to complete 20S CP gate opening. In the resulting substrate processing state, the ATPase channel is fully contiguous with the translocation channel into the 20S CP, where the substrate is proteolyzed. Complete degradation of a typical ubiquitin-conjugate takes place over a few tens of seconds while hydrolysing tens of ATP molecules in the process (50 kDa/∼50 s/∼80ATP). This article reviews recent insight into biochemical and structural features that underlie substrate recognition and processing by the 26S proteasome.
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20
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Abstract
The 26S proteasome is the most complex ATP-dependent protease machinery, of ~2.5 MDa mass, ubiquitously found in all eukaryotes. It selectively degrades ubiquitin-conjugated proteins and plays fundamentally indispensable roles in regulating almost all major aspects of cellular activities. To serve as the sole terminal "processor" for myriad ubiquitylation pathways, the proteasome evolved exceptional adaptability in dynamically organizing a large network of proteins, including ubiquitin receptors, shuttle factors, deubiquitinases, AAA-ATPase unfoldases, and ubiquitin ligases, to enable substrate selectivity and processing efficiency and to achieve regulation precision of a vast diversity of substrates. The inner working of the 26S proteasome is among the most sophisticated, enigmatic mechanisms of enzyme machinery in eukaryotic cells. Recent breakthroughs in three-dimensional atomic-level visualization of the 26S proteasome dynamics during polyubiquitylated substrate degradation elucidated an extensively detailed picture of its functional mechanisms, owing to progressive methodological advances associated with cryogenic electron microscopy (cryo-EM). Multiple sites of ubiquitin binding in the proteasome revealed a canonical mode of ubiquitin-dependent substrate engagement. The proteasome conformation in the act of substrate deubiquitylation provided insights into how the deubiquitylating activity of RPN11 is enhanced in the holoenzyme and is coupled to substrate translocation. Intriguingly, three principal modes of coordinated ATP hydrolysis in the heterohexameric AAA-ATPase motor were discovered to regulate intermediate functional steps of the proteasome, including ubiquitin-substrate engagement, deubiquitylation, initiation of substrate translocation and processive substrate degradation. The atomic dissection of the innermost working of the 26S proteasome opens up a new era in our understanding of the ubiquitin-proteasome system and has far-reaching implications in health and disease.
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Affiliation(s)
- Youdong Mao
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, 02215, Massachusetts, USA. .,School of Physics, Center for Quantitative Biology, Peking University, Beijing, 100871, China.
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21
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Molecular and cellular dynamics of the 26S proteasome. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020; 1869:140583. [PMID: 33321258 DOI: 10.1016/j.bbapap.2020.140583] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 12/07/2020] [Accepted: 12/09/2020] [Indexed: 01/16/2023]
Abstract
In eukaryotic cells, the ubiquitin-proteasome system serves to remove proteins that are either dysfunctional or no longer needed. The 26S proteasome is a 2.5 MDa multisubunit complex comprising the 20S core particle, where degradation is executed, and one or two regulatory particles which prepare substrates for degradation. Whereas the 20S core particles of several species had been studied extensively by X-ray crystallography, the 26S holocomplex structure had remained elusive for a long time. Recent advances in single-particle cryo-electron microscopy have changed the situation and provided atomic resolution models of this intriguing molecular machine and its dynamics. Besides, cryo-electron tomography enables structural studies in situ, providing molecular resolution images of macromolecules inside pristinely preserved cellular environments. This has greatly contributed to our understanding of proteasome dynamics in the context of cells.
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22
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Račková L, Csekes E. Proteasome Biology: Chemistry and Bioengineering Insights. Polymers (Basel) 2020; 12:E2909. [PMID: 33291646 PMCID: PMC7761984 DOI: 10.3390/polym12122909] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 11/22/2020] [Accepted: 11/23/2020] [Indexed: 12/12/2022] Open
Abstract
Proteasomal degradation provides the crucial machinery for maintaining cellular proteostasis. The biological origins of modulation or impairment of the function of proteasomal complexes may include changes in gene expression of their subunits, ubiquitin mutation, or indirect mechanisms arising from the overall impairment of proteostasis. However, changes in the physico-chemical characteristics of the cellular environment might also meaningfully contribute to altered performance. This review summarizes the effects of physicochemical factors in the cell, such as pH, temperature fluctuations, and reactions with the products of oxidative metabolism, on the function of the proteasome. Furthermore, evidence of the direct interaction of proteasomal complexes with protein aggregates is compared against the knowledge obtained from immobilization biotechnologies. In this regard, factors such as the structures of the natural polymeric scaffolds in the cells, their content of reactive groups or the sequestration of metal ions, and processes at the interface, are discussed here with regard to their influences on proteasomal function.
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Affiliation(s)
- Lucia Račková
- Centre of Experimental Medicine, Institute of Experimental Pharmacology and Toxicology, Slovak Academy of Sciences, Dúbravská cesta 9, 841 04 Bratislava, Slovakia;
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23
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Lesne J, Locard-Paulet M, Parra J, Zivković D, Menneteau T, Bousquet MP, Burlet-Schiltz O, Marcoux J. Conformational maps of human 20S proteasomes reveal PA28- and immuno-dependent inter-ring crosstalks. Nat Commun 2020; 11:6140. [PMID: 33262340 PMCID: PMC7708635 DOI: 10.1038/s41467-020-19934-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 11/06/2020] [Indexed: 01/17/2023] Open
Abstract
Hydrogen-Deuterium eXchange coupled to Mass Spectrometry (HDX-MS) is now common practice in structural biology. However, it is most of the time applied to rather small oligomeric complexes. Here, we report on the use of HDX-MS to investigate conformational differences between the human standard 20S (std20S) and immuno 20S (i20s) proteasomes alone or in complex with PA28αβ or PA28γ activators. Their solvent accessibility is analyzed through a dedicated bioinformatic pipeline including stringent statistical analysis and 3D visualization. These data confirm the existence of allosteric differences between the std20S and i20S at the surface of the α-ring triggered from inside the catalytic β-ring. Additionally, binding of the PA28 regulators to the 20S proteasomes modify solvent accessibility due to conformational changes of the β-rings. This work is not only a proof-of-concept that HDX-MS can be used to get structural insights on large multi-protein complexes in solution, it also demonstrates that the binding of the std20S or i20S subtype to any of its PA28 activator triggers allosteric changes that are specific to this 20S/PA28 pair.
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Affiliation(s)
- Jean Lesne
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, UPS, Toulouse, France
- Centre de Biologie Structurale, CNRS, Université de Montpellier, INSERM, 34090, Montpellier, France
| | - Marie Locard-Paulet
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, UPS, Toulouse, France
- Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
| | - Julien Parra
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Dušan Zivković
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Thomas Menneteau
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, UPS, Toulouse, France
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK
| | - Marie-Pierre Bousquet
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Odile Burlet-Schiltz
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Julien Marcoux
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, UPS, Toulouse, France.
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Chen X, Dorris Z, Shi D, Huang RK, Khant H, Fox T, de Val N, Williams D, Zhang P, Walters KJ. Cryo-EM Reveals Unanchored M1-Ubiquitin Chain Binding at hRpn11 of the 26S Proteasome. Structure 2020; 28:1206-1217.e4. [PMID: 32783951 PMCID: PMC7642156 DOI: 10.1016/j.str.2020.07.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 07/06/2020] [Accepted: 07/22/2020] [Indexed: 12/17/2022]
Abstract
The 26S proteasome is specialized for regulated protein degradation and formed by a dynamic regulatory particle (RP) that caps a hollow cylindrical core particle (CP) where substrates are proteolyzed. Its diverse substrates unify as proteasome targets by ubiquitination. We used cryogenic electron microscopy (cryo-EM) to study how human 26S proteasome interacts with M1-linked hexaubiquitin (M1-Ub6) unanchored to a substrate and E3 ubiquitin ligase E6AP/UBE3A. Proteasome structures are available with model substrates extending through the RP ATPase ring and substrate-conjugated K63-linked ubiquitin chains present at inhibited deubiquitinating enzyme hRpn11 and the nearby ATPase hRpt4/hRpt5 coiled coil. In this study, we find M1-Ub6 at the hRpn11 site despite the absence of conjugated substrate, indicating that ubiquitin binding at this location does not require substrate interaction with the RP. Moreover, unanchored M1-Ub6 binds to this hRpn11 site of the proteasome with the CP gating residues in both the closed and opened conformational states.
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Affiliation(s)
- Xiang Chen
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Zachary Dorris
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA; Frederick High School, Frederick, MD 21702, USA
| | - Dan Shi
- Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Rick K Huang
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - Htet Khant
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA; Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research Inc, Frederick, MD 21701, USA
| | - Tara Fox
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA; Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research Inc, Frederick, MD 21701, USA
| | - Natalia de Val
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA; Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research Inc, Frederick, MD 21701, USA
| | - Dewight Williams
- John M. Cowley Center for High Resolution Electron Microscopy, Arizona State University, Tempe, AZ 85287, USA
| | - Ping Zhang
- Kinase Complexes Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Kylie J Walters
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA.
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25
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Majumder P, Baumeister W. Proteasomes: unfoldase-assisted protein degradation machines. Biol Chem 2020; 401:183-199. [PMID: 31665105 DOI: 10.1515/hsz-2019-0344] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 10/02/2019] [Indexed: 01/05/2023]
Abstract
Proteasomes are the principal molecular machines for the regulated degradation of intracellular proteins. These self-compartmentalized macromolecular assemblies selectively degrade misfolded, mistranslated, damaged or otherwise unwanted proteins, and play a pivotal role in the maintenance of cellular proteostasis, in stress response, and numerous other processes of vital importance. Whereas the molecular architecture of the proteasome core particle (CP) is universally conserved, the unfoldase modules vary in overall structure, subunit complexity, and regulatory principles. Proteasomal unfoldases are AAA+ ATPases (ATPases associated with a variety of cellular activities) that unfold protein substrates, and translocate them into the CP for degradation. In this review, we summarize the current state of knowledge about proteasome - unfoldase systems in bacteria, archaea, and eukaryotes, the three domains of life.
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Affiliation(s)
- Parijat Majumder
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany
| | - Wolfgang Baumeister
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany
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26
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Gong Z, Ye SX, Tang C. Tightening the Crosslinking Distance Restraints for Better Resolution of Protein Structure and Dynamics. Structure 2020; 28:1160-1167.e3. [PMID: 32763142 DOI: 10.1016/j.str.2020.07.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 07/04/2020] [Accepted: 07/21/2020] [Indexed: 12/11/2022]
Abstract
Chemical crosslinking coupled with mass spectrometry (CXMS) has been increasingly used in structural biology. CXMS distance restraints are usually applied to Cα or Cβ atoms of the crosslinked residues, with upper bounds typically over 20 Å. The incorporation of loose CXMS restraints only marginally improves the resolution of the calculated structures. Here, we present a revised format of CXMS distance restraints, which works by first modifying the crosslinked residue with a rigid extension derived from the crosslinker. With the flexible side chain explicitly represented, the reformatted restraint can be applied to the modification group instead, with an upper bound of 6 Å or less. The short distance restraint can be represented and back-calculated simply with a straight line. The use of tighter restraints not only afford better-resolved structures but also uncover protein dynamics. Together, our approach enables more information extracted from the CXMS data.
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Affiliation(s)
- Zhou Gong
- CAS Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, National Center for Magnetic Resonance at Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, Hubei Province 430071, China
| | - Shang-Xiang Ye
- CAS Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, National Center for Magnetic Resonance at Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, Hubei Province 430071, China; Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei Province 430074, China
| | - Chun Tang
- CAS Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, National Center for Magnetic Resonance at Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, Hubei Province 430071, China; Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei Province 430074, China; Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China.
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27
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Shin JY, Muniyappan S, Tran NN, Park H, Lee SB, Lee BH. Deubiquitination Reactions on the Proteasome for Proteasome Versatility. Int J Mol Sci 2020; 21:E5312. [PMID: 32726943 PMCID: PMC7432943 DOI: 10.3390/ijms21155312] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 07/21/2020] [Accepted: 07/23/2020] [Indexed: 12/17/2022] Open
Abstract
The 26S proteasome, a master player in proteolysis, is the most complex and meticulously contextured protease in eukaryotic cells. While capable of hosting thousands of discrete substrates due to the selective recognition of ubiquitin tags, this protease complex is also dynamically checked through diverse regulatory mechanisms. The proteasome's versatility ensures precise control over active proteolysis, yet prevents runaway or futile degradation of many essential cellular proteins. Among the multi-layered processes regulating the proteasome's proteolysis, deubiquitination reactions are prominent because they not only recycle ubiquitins, but also impose a critical checkpoint for substrate degradation on the proteasome. Of note, three distinct classes of deubiquitinating enzymes-USP14, RPN11, and UCH37-are associated with the 19S subunits of the human proteasome. Recent biochemical and structural studies suggest that these enzymes exert dynamic influence over proteasome output with limited redundancy, and at times act in opposition. Such distinct activities occur spatially on the proteasome, temporally through substrate processing, and differentially for ubiquitin topology. Therefore, deubiquitinating enzymes on the proteasome may fine-tune the degradation depending on various cellular contexts and for dynamic proteolysis outcomes. Given that the proteasome is among the most important drug targets, the biology of proteasome-associated deubiquitination should be further elucidated for its potential targeting in human diseases.
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Affiliation(s)
- Ji Yeong Shin
- Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea; (J.Y.S.); (S.M.); (N.-N.T.); (H.P.)
- Protein Dynamics-based Proteotoxicity Control Lab, Basic Research Lab, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea;
- Center for Cell Fate Reprogramming & Control, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Srinivasan Muniyappan
- Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea; (J.Y.S.); (S.M.); (N.-N.T.); (H.P.)
| | - Non-Nuoc Tran
- Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea; (J.Y.S.); (S.M.); (N.-N.T.); (H.P.)
- Protein Dynamics-based Proteotoxicity Control Lab, Basic Research Lab, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea;
- Center for Cell Fate Reprogramming & Control, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Hyeonjeong Park
- Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea; (J.Y.S.); (S.M.); (N.-N.T.); (H.P.)
- Protein Dynamics-based Proteotoxicity Control Lab, Basic Research Lab, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea;
| | - Sung Bae Lee
- Protein Dynamics-based Proteotoxicity Control Lab, Basic Research Lab, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea;
- Department of Brain & Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Byung-Hoon Lee
- Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea; (J.Y.S.); (S.M.); (N.-N.T.); (H.P.)
- Protein Dynamics-based Proteotoxicity Control Lab, Basic Research Lab, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea;
- Center for Cell Fate Reprogramming & Control, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
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28
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The degradation-promoting roles of deubiquitinases Ubp6 and Ubp3 in cytosolic and ER protein quality control. PLoS One 2020; 15:e0232755. [PMID: 32401766 PMCID: PMC7219781 DOI: 10.1371/journal.pone.0232755] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 04/21/2020] [Indexed: 11/19/2022] Open
Abstract
The quality control of intracellular proteins is achieved by degrading misfolded proteins which cannot be refolded by molecular chaperones. In eukaryotes, such degradation is handled primarily by the ubiquitin-proteasome system. However, it remained unclear whether and how protein quality control deploys various deubiquitinases. To address this question, we screened deletions or mutation of the 20 deubiquitinase genes in Saccharomyces cerevisiae and discovered that almost half of the mutations slowed the removal of misfolded proteins whereas none of the remaining mutations accelerated this process significantly. Further characterization revealed that Ubp6 maintains the level of free ubiquitin to promote the elimination of misfolded cytosolic proteins, while Ubp3 supports the degradation of misfolded cytosolic and ER luminal proteins by different mechanisms.
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Proteins containing ubiquitin-like (Ubl) domains not only bind to 26S proteasomes but also induce their activation. Proc Natl Acad Sci U S A 2020; 117:4664-4674. [PMID: 32071216 DOI: 10.1073/pnas.1915534117] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
During protein degradation by the ubiquitin-proteasome pathway, latent 26S proteasomes in the cytosol must assume an active form. Proteasomes are activated when ubiquitylated substrates bind to them and interact with the proteasome-bound deubiquitylase Usp14/Ubp6. The resulting increase in the proteasome's degradative activity was recently shown to be mediated by Usp14's ubiquitin-like (Ubl) domain, which, by itself, can trigger proteasome activation. Many other proteins with diverse cellular functions also contain Ubl domains and can associate with 26S proteasomes. We therefore tested if various Ubl-containing proteins that have important roles in protein homeostasis or disease also activate 26S proteasomes. All seven Ubl-containing proteins tested-the shuttling factors Rad23A, Rad23B, and Ddi2; the deubiquitylase Usp7, the ubiquitin ligase Parkin, the cochaperone Bag6, and the protein phosphatase UBLCP1-stimulated peptide hydrolysis two- to fivefold. Rather than enhancing already active proteasomes, Rad23B and its Ubl domain activated previously latent 26S particles. Also, Ubl-containing proteins (if present with an unfolded protein) increased proteasomal adenosine 5'-triphosphate (ATP) hydrolysis, the step which commits substrates to degradation. Surprisingly, some of these proteins also could stimulate peptide hydrolysis even when their Ubl domains were deleted. However, their Ubl domains were required for the increased ATPase activity. Thus, upon binding to proteasomes, Ubl-containing proteins not only deliver substrates (e.g., the shuttling factors) or provide additional enzymatic activities (e.g., Parkin) to proteasomes, but also increase their capacity for proteolysis.
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30
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Finley D, Prado MA. The Proteasome and Its Network: Engineering for Adaptability. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a033985. [PMID: 30833452 DOI: 10.1101/cshperspect.a033985] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The proteasome, the most complex protease known, degrades proteins that have been conjugated to ubiquitin. It faces the unique challenge of acting enzymatically on hundreds and perhaps thousands of structurally diverse substrates, mechanically unfolding them from their native state and translocating them vectorially from one specialized compartment of the enzyme to another. Moreover, substrates are modified by ubiquitin in myriad configurations of chains. The many unusual design features of the proteasome may have evolved in part to endow this enzyme with a robust ability to process substrates regardless of their identity. The proteasome plays a major role in preserving protein homeostasis in the cell, which requires adaptation to a wide variety of stress conditions. Modulation of proteasome function is achieved through a large network of proteins that interact with it dynamically, modify it enzymatically, or fine-tune its levels. The resulting adaptability of the proteasome, which is unique among proteases, enables cells to control the output of the ubiquitin-proteasome pathway on a global scale.
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Affiliation(s)
- Daniel Finley
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115
| | - Miguel A Prado
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115
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31
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Srinivasan V, Bruelle C, Scifo E, Pham DD, Soliymani R, Lalowski M, Lindholm D. Dynamic Interaction of USP14 with the Chaperone HSC70 Mediates Crosstalk between the Proteasome, ER Signaling, and Autophagy. iScience 2019; 23:100790. [PMID: 31901637 PMCID: PMC6941875 DOI: 10.1016/j.isci.2019.100790] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 11/22/2019] [Accepted: 12/13/2019] [Indexed: 01/01/2023] Open
Abstract
USP14 is a deubiquitinating enzyme associated with the proteasome important for protein degradation. Here we show that upon proteasome inhibition or expression of the mutant W58A-USP14, association of USP14 with the 19S regulatory particle is disrupted. MS-based interactomics revealed an interaction of USP14 with the chaperone, HSC70, in neuroblastoma cells. Proteasome inhibition enhanced binding of USP14 to HSC70, and to XBP1u and IRE1α proteins, demonstrating a role in the unfolded protein response. Striatal neurons expressing mutant huntingtin exhibited reduced USP14 and HSC70 levels, whereas inhibition of HSC70 downregulated USP14. Furthermore, proteasome inhibition or use of the mutant W58A-USP14 facilitated the interaction of USP14 with the autophagy protein, GABARAP. Functionally, overexpression of W58A-USP14 increased GABARAP positive autophagosomes in striatal neurons, and this was abrogated using the HSC70 inhibitor, VER-155008. Modulation of the USP14-HSC70 axis may represent a potential therapeutic target in HD to beneficially influence multiple proteostasis pathways. USP14 binds HSC70 upon proteasome inhibition This rises GABARAP autophagosomes in HD
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Affiliation(s)
- Vignesh Srinivasan
- Medicum, Department of Biochemistry and Developmental Biology, Faculty of MedicineUniversity of Helsinki, P.O. Box 63, FIN-00014 Helsinki, Finland; Minerva Foundation Institute for Medical Research, Biomedicum Helsinki 2U, Tukholmankatu 8, FIN-00290 Helsinki, Finland
| | - Celine Bruelle
- Medicum, Department of Biochemistry and Developmental Biology, Faculty of MedicineUniversity of Helsinki, P.O. Box 63, FIN-00014 Helsinki, Finland; Minerva Foundation Institute for Medical Research, Biomedicum Helsinki 2U, Tukholmankatu 8, FIN-00290 Helsinki, Finland
| | - Enzo Scifo
- Medicum, Department of Biochemistry and Developmental Biology, Faculty of MedicineUniversity of Helsinki, P.O. Box 63, FIN-00014 Helsinki, Finland; Molecular and Cellular Cognition Lab, German Center for Neurodegenerative Diseases, Venusberg-Campus 1, Building 99, 53127 Bonn, Germany
| | - Dan Duc Pham
- Medicum, Department of Biochemistry and Developmental Biology, Faculty of MedicineUniversity of Helsinki, P.O. Box 63, FIN-00014 Helsinki, Finland; Minerva Foundation Institute for Medical Research, Biomedicum Helsinki 2U, Tukholmankatu 8, FIN-00290 Helsinki, Finland
| | - Rabah Soliymani
- Medicum, Department of Biochemistry and Developmental Biology, Faculty of MedicineUniversity of Helsinki, P.O. Box 63, FIN-00014 Helsinki, Finland; Meilahti Clinical Proteomics Core Facility HiLIFE, University of Helsinki, Helsinki, Finland
| | - Maciej Lalowski
- Medicum, Department of Biochemistry and Developmental Biology, Faculty of MedicineUniversity of Helsinki, P.O. Box 63, FIN-00014 Helsinki, Finland; Meilahti Clinical Proteomics Core Facility HiLIFE, University of Helsinki, Helsinki, Finland
| | - Dan Lindholm
- Medicum, Department of Biochemistry and Developmental Biology, Faculty of MedicineUniversity of Helsinki, P.O. Box 63, FIN-00014 Helsinki, Finland; Minerva Foundation Institute for Medical Research, Biomedicum Helsinki 2U, Tukholmankatu 8, FIN-00290 Helsinki, Finland.
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32
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Eisele MR, Reed RG, Rudack T, Schweitzer A, Beck F, Nagy I, Pfeifer G, Plitzko JM, Baumeister W, Tomko RJ, Sakata E. Expanded Coverage of the 26S Proteasome Conformational Landscape Reveals Mechanisms of Peptidase Gating. Cell Rep 2019; 24:1301-1315.e5. [PMID: 30067984 PMCID: PMC6140342 DOI: 10.1016/j.celrep.2018.07.004] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 06/08/2018] [Accepted: 07/02/2018] [Indexed: 12/31/2022] Open
Abstract
The proteasome is the central protease for intracellular protein breakdown. Coordinated binding and hydrolysis of ATP by the six proteasomal ATPase subunits induces conformational changes that drive the unfolding and translocation of substrates into the proteolytic 20S core particle for degradation. Here, we combine genetic and biochemical approaches with cryo-electron microscopy and integrative modeling to dissect the relationship between individual nucleotide binding events and proteasome conformational dynamics. We demonstrate unique impacts of ATP binding by individual ATPases on the proteasome conformational distribution and report two conformational states of the proteasome suggestive of a rotary ATP hydrolysis mechanism. These structures, coupled with functional analyses, reveal key roles for the ATPases Rpt1 and Rpt6 in gating substrate entry into the core particle. This deepened knowledge of proteasome conformational dynamics reveals key elements of intersubunit communication within the proteasome and clarifies the regulation of substrate entry into the proteolytic chamber.
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Affiliation(s)
- Markus R Eisele
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Randi G Reed
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL 32306-4300, USA
| | - Till Rudack
- Department of Biophysics, Ruhr University Bochum, 44801 Bochum, Germany
| | - Andreas Schweitzer
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Florian Beck
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Istvan Nagy
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Günter Pfeifer
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Jürgen M Plitzko
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Wolfgang Baumeister
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
| | - Robert J Tomko
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL 32306-4300, USA.
| | - Eri Sakata
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
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33
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Greene ER, Goodall EA, de la Peña AH, Matyskiela ME, Lander GC, Martin A. Specific lid-base contacts in the 26s proteasome control the conformational switching required for substrate degradation. eLife 2019; 8:49806. [PMID: 31778111 PMCID: PMC6910829 DOI: 10.7554/elife.49806] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Accepted: 11/27/2019] [Indexed: 12/21/2022] Open
Abstract
The 26S proteasome is essential for proteostasis and the regulation of vital processes through ATP-dependent degradation of ubiquitinated substrates. To accomplish the multi-step degradation process, the proteasome's regulatory particle, consisting of lid and base subcomplexes, undergoes major conformational changes whose origin is unknown. Investigating the Saccharomyces cerevisiae proteasome, we found that peripheral interactions between the lid subunit Rpn5 and the base AAA+ ATPase ring are important for stabilizing the substrate-engagement-competent state and coordinating the conformational switch to processing states upon substrate engagement. Disrupting these interactions perturbs the conformational equilibrium and interferes with degradation initiation, while later processing steps remain unaffected. Similar defects in early degradation steps are observed when eliminating hydrolysis in the ATPase subunit Rpt6, whose nucleotide state seems to control proteasome conformational transitions. These results provide important insight into interaction networks that coordinate conformational changes with various stages of degradation, and how modulators of conformational equilibria may influence substrate turnover.
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Affiliation(s)
- Eric R Greene
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, United States
| | - Ellen A Goodall
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, United States
| | - Andres H de la Peña
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, United States
| | - Mary E Matyskiela
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, United States
| | - Gabriel C Lander
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, United States
| | - Andreas Martin
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, United States.,Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States
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34
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Greene ER, Dong KC, Martin A. Understanding the 26S proteasome molecular machine from a structural and conformational dynamics perspective. Curr Opin Struct Biol 2019; 61:33-41. [PMID: 31783300 DOI: 10.1016/j.sbi.2019.10.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 10/14/2019] [Accepted: 10/15/2019] [Indexed: 12/30/2022]
Abstract
The 26S proteasome is the essential compartmental protease in eukaryotic cells required for the ubiquitin-dependent clearance of damaged polypeptides and obsolete regulatory proteins. Recently, a combination of high-resolution structural, biochemical, and biophysical studies has provided crucial new insights into the mechanisms of this fascinating molecular machine. A multitude of new cryo-electron microscopy structures provided snapshots of the proteasome during ATP-hydrolysis-driven substrate translocation, and detailed biochemical studies revealed the timing of individual degradation steps, elucidating the mechanisms for substrate selection and the commitment to degradation through conformational transitions. It was uncovered how ubiquitin removal from substrates is mechanically coupled to degradation, and cryo-electron tomography studies gave a glimpse of active proteasomes inside the cell, their subcellular localization, and interactions with protein aggregates. Here, we summarize these advances in our mechanistic understanding of the proteasome, with a particular focus on how its structural features and conformational transitions enable the multi-step degradation process.
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Affiliation(s)
- Eric R Greene
- Department of Molecular Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, University of California Berkeley, Berkeley, CA 94720, USA
| | - Ken C Dong
- Department of Molecular Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, University of California Berkeley, Berkeley, CA 94720, USA; Howard Hughes Medical Institute, University of California Berkeley, Berkeley, CA 94720, USA
| | - Andreas Martin
- Department of Molecular Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, University of California Berkeley, Berkeley, CA 94720, USA; Howard Hughes Medical Institute, University of California Berkeley, Berkeley, CA 94720, USA.
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35
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Chadchankar J, Korboukh V, Conway LC, Wobst HJ, Walker CA, Doig P, Jacobsen SJ, Brandon NJ, Moss SJ, Wang Q. Inactive USP14 and inactive UCHL5 cause accumulation of distinct ubiquitinated proteins in mammalian cells. PLoS One 2019; 14:e0225145. [PMID: 31703099 PMCID: PMC6839854 DOI: 10.1371/journal.pone.0225145] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 10/29/2019] [Indexed: 12/12/2022] Open
Abstract
USP14 is a cysteine protease deubiquitinase associated with the proteasome and plays important catalytic and allosteric roles in proteasomal degradation. USP14 inhibition has been considered a therapeutic strategy for accelerating degradation of aggregation-prone proteins in neurodegenerative diseases and for inhibiting proteasome function to induce apoptotic cell death in cancers. Here we studied the effects of USP14 inhibition in mammalian cells using small molecule inhibitors and an inactive USP14 mutant C114A. Neither the inhibitors nor USP14 C114A showed consistent or significant effects on the level of TDP-43, tau or α-synuclein in HEK293T cells. However, USP14 C114A led to a robust accumulation of ubiquitinated proteins, which were isolated by ubiquitin immunoprecipitation and identified by mass spectrometry. Among these proteins we confirmed that ubiquitinated β-catenin accumulated in the cells expressing USP14 C114A with immunoblotting and immunoprecipitation experiments. The proteasome binding domain of USP14 C114A is required for its effect on ubiquitinated proteins. UCHL5 is the other cysteine protease deubiquitinase associated with the proteasome. Interestingly, the inactive mutant of UCHL5 C88A also caused an accumulation of ubiquitinated proteins in HEK293T cells but did not affect β-catenin, demonstrating USP14 but not UCHL5 has a specific effect on β-catenin. We used ubiquitin immunoprecipitation and mass spectrometry to identify the accumulated ubiquitinated proteins in UCHL5 C88A expressing cells which are mostly distinct from those identified in USP14 C114A expressing cells. Among the identified proteins are well established proteasome substrates and proteasome subunits. Besides β-catenin, we also verified with immunoblotting that UCHL5 C88A inhibits its own deubiquitination and USP14 C114A inhibits deubiquitination of two proteasomal subunits PSMC1 and PSMD4. Together our data suggest that USP14 and UCHL5 can deubiquitinate distinct substrates at the proteasome and regulate the ubiquitination of the proteasome itself which is tightly linked to its function.
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Affiliation(s)
- Jayashree Chadchankar
- AstraZeneca Tufts Laboratory for Basic and Translational Neuroscience, Tufts University, Boston, MA, United States of America
| | - Victoria Korboukh
- Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Waltham, MA, United States of America
| | - Leslie C. Conway
- AstraZeneca Tufts Laboratory for Basic and Translational Neuroscience, Tufts University, Boston, MA, United States of America
| | - Heike J. Wobst
- Neuroscience, BioPharmaceuticals R&D, AstraZeneca, Waltham, MA, United States of America
| | - Chandler A. Walker
- Neuroscience, BioPharmaceuticals R&D, AstraZeneca, Waltham, MA, United States of America
| | - Peter Doig
- Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Waltham, MA, United States of America
| | - Steve J. Jacobsen
- Neuroscience, BioPharmaceuticals R&D, AstraZeneca, Waltham, MA, United States of America
| | - Nicholas J. Brandon
- Neuroscience, BioPharmaceuticals R&D, AstraZeneca, Waltham, MA, United States of America
| | - Stephen J. Moss
- Neuroscience, BioPharmaceuticals R&D, AstraZeneca, Waltham, MA, United States of America
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States of America
- Department of Neuroscience, Physiology and Pharmacology, University College, London, United Kingdom
| | - Qi Wang
- Neuroscience, BioPharmaceuticals R&D, AstraZeneca, Waltham, MA, United States of America
- * E-mail:
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36
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Kudriaeva AA, Belogurov AA. Proteasome: a Nanomachinery of Creative Destruction. BIOCHEMISTRY (MOSCOW) 2019; 84:S159-S192. [PMID: 31213201 DOI: 10.1134/s0006297919140104] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
In the middle of the 20th century, it was postulated that degradation of intracellular proteins is a stochastic process. More than fifty years of intense studies have finally proven that protein degradation is a very complex and tightly regulated in time and space process that plays an incredibly important role in the vast majority of metabolic pathways. Degradation of more than a half of intracellular proteins is controlled by a hierarchically aligned and evolutionarily perfect system consisting of many components, the main ones being ubiquitin ligases and proteasomes, together referred to as the ubiquitin-proteasome system (UPS). The UPS includes more than 1000 individual components, and most of them are critical for the cell functioning and survival. In addition to the well-known signaling functions of ubiquitination, such as modification of substrates for proteasomal degradation and DNA repair, polyubiquitin (polyUb) chains are involved in other important cellular processes, e.g., cell cycle regulation, immunity, protein degradation in mitochondria, and even mRNA stability. This incredible variety of ubiquitination functions is related to the ubiquitin ability to form branching chains through the ε-amino group of any of seven lysine residues in its sequence. Deubiquitination is accomplished by proteins of the deubiquitinating enzyme family. The second main component of the UPS is proteasome, a multisubunit proteinase complex that, in addition to the degradation of functionally exhausted and damaged proteins, regulates many important cellular processes through controlled degradation of substrates, for example, transcription factors and cyclins. In addition to the ubiquitin-dependent-mediated degradation, there is also ubiquitin-independent degradation, when the proteolytic signal is either an intrinsic protein sequence or shuttle molecule. Protein hydrolysis is a critically important cellular function; therefore, any abnormalities in this process lead to systemic impairments further transforming into serious diseases, such as diabetes, malignant transformation, and neurodegenerative disorders (multiple sclerosis, Alzheimer's disease, Parkinson's disease, Creutzfeldt-Jakob disease and Huntington's disease). In this review, we discuss the mechanisms that orchestrate all components of the UPS, as well as the plurality of the fine-tuning pathways of proteasomal degradation.
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Affiliation(s)
- A A Kudriaeva
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia.
| | - A A Belogurov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia. .,Lomonosov Moscow State University, Moscow, 119991, Russia
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37
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Marshall RS, Vierstra RD. Dynamic Regulation of the 26S Proteasome: From Synthesis to Degradation. Front Mol Biosci 2019; 6:40. [PMID: 31231659 PMCID: PMC6568242 DOI: 10.3389/fmolb.2019.00040] [Citation(s) in RCA: 143] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 05/09/2019] [Indexed: 01/12/2023] Open
Abstract
All eukaryotes rely on selective proteolysis to control the abundance of key regulatory proteins and maintain a healthy and properly functioning proteome. Most of this turnover is catalyzed by the 26S proteasome, an intricate, multi-subunit proteolytic machine. Proteasomes recognize and degrade proteins first marked with one or more chains of poly-ubiquitin, the addition of which is actuated by hundreds of ligases that individually identify appropriate substrates for ubiquitylation. Subsequent proteasomal digestion is essential and influences a myriad of cellular processes in species as diverse as plants, fungi and humans. Importantly, dysfunction of 26S proteasomes is associated with numerous human pathologies and profoundly impacts crop performance, thus making an understanding of proteasome dynamics critically relevant to almost all facets of human health and nutrition. Given this widespread significance, it is not surprising that sophisticated mechanisms have evolved to tightly regulate 26S proteasome assembly, abundance and activity in response to demand, organismal development and stress. These include controls on transcription and chaperone-mediated assembly, influences on proteasome localization and activity by an assortment of binding proteins and post-translational modifications, and ultimately the removal of excess or damaged particles via autophagy. Intriguingly, the autophagic clearance of damaged 26S proteasomes first involves their modification with ubiquitin, thus connecting ubiquitylation and autophagy as key regulatory events in proteasome quality control. This turnover is also influenced by two distinct biomolecular condensates that coalesce in the cytoplasm, one attracting damaged proteasomes for autophagy, and the other reversibly storing proteasomes during carbon starvation to protect them from autophagic clearance. In this review, we describe the current state of knowledge regarding the dynamic regulation of 26S proteasomes at all stages of their life cycle, illustrating how protein degradation through this proteolytic machine is tightly controlled to ensure optimal growth, development and longevity.
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Affiliation(s)
- Richard S Marshall
- Department of Biology, Washington University in St. Louis, St. Louis, MO, United States
| | - Richard D Vierstra
- Department of Biology, Washington University in St. Louis, St. Louis, MO, United States
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38
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Bard JAM, Bashore C, Dong KC, Martin A. The 26S Proteasome Utilizes a Kinetic Gateway to Prioritize Substrate Degradation. Cell 2019; 177:286-298.e15. [PMID: 30929903 DOI: 10.1016/j.cell.2019.02.031] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 12/22/2018] [Accepted: 02/19/2019] [Indexed: 11/28/2022]
Abstract
The 26S proteasome is the principal macromolecular machine responsible for protein degradation in eukaryotes. However, little is known about the detailed kinetics and coordination of the underlying substrate-processing steps of the proteasome, and their correlation with observed conformational states. Here, we used reconstituted 26S proteasomes with unnatural amino-acid-attached fluorophores in a series of FRET- and anisotropy-based assays to probe substrate-proteasome interactions, the individual steps of the processing pathway, and the conformational state of the proteasome itself. We develop a complete kinetic picture of proteasomal degradation, which reveals that the engagement steps prior to substrate commitment are fast relative to subsequent deubiquitination, translocation, and unfolding. Furthermore, we find that non-ideal substrates are rapidly rejected by the proteasome, which thus employs a kinetic proofreading mechanism to ensure degradation fidelity and substrate prioritization.
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Affiliation(s)
- Jared A M Bard
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Charlene Bashore
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Ken C Dong
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, CA 94720, USA; Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Andreas Martin
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, CA 94720, USA; Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, CA 94720, USA.
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39
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Fang Z, Baghdady YZ, Schug KA, Chowdhury SM. Evaluation of Different Stationary Phases in the Separation of Inter-Cross-Linked Peptides. J Proteome Res 2019; 18:1916-1925. [PMID: 30786713 DOI: 10.1021/acs.jproteome.9b00114] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Chemical cross-linking coupled with mass spectrometry (MS) is becoming a routinely and widely used technique for depicting and constructing protein structures and protein interaction networks. One major challenge for cross-linking/MS is the determination of informative low-abundant inter-cross-linked products, generated within a sample of high complexity. A C18 stationary phase is the conventional means for reversed-phase (RP) separation of inter-cross-linked peptides. Various RP stationary phases, which provide different selectivities and retentions, have been developed as alternatives to C18 stationary phases. In this study, two phenyl-based columns, biphenyl and fluorophenyl, were investigated and compared with a C18 phase for separating BS3 (bis(sulfosuccinimidyl)suberate) cross-linked bovine serum albumin (BSA) and myoglobin by bottom-up proteomics. Fractions from the three columns were collected and analyzed in a linear ion trap (LIT) mass spectrometer for improving detection of low abundant inter-cross-linked peptides. Among these three columns, the fluorophenyl column provides additional ion-exchange interaction and exhibits unique retention in separating the cross-linked peptides. The fractioned data was analyzed in pLink, showing the fluorophenyl column consistently obtained more inter-cross-linked peptide identifications than both C18 and biphenyl columns. For the BSA cross-linked sample, the identified inter-cross-linked peptide numbers of the fluorophenyl to C18 column are 136 to 102 in "low confident" results and 11 to 6 in "high confident" results. The fluorophenyl column could potentially be a better alternative for targeting the low stoichiometric inter-cross-linked peptides.
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Affiliation(s)
- Zixiang Fang
- Department of Chemistry & Biochemistry , The University of Texas at Arlington , Arlington , Texas 76019 , United States
| | - Yehia Z Baghdady
- Department of Chemistry & Biochemistry , The University of Texas at Arlington , Arlington , Texas 76019 , United States
| | - Kevin A Schug
- Department of Chemistry & Biochemistry , The University of Texas at Arlington , Arlington , Texas 76019 , United States
| | - Saiful M Chowdhury
- Department of Chemistry & Biochemistry , The University of Texas at Arlington , Arlington , Texas 76019 , United States
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40
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Co-translational assembly of proteasome subunits in NOT1-containing assemblysomes. Nat Struct Mol Biol 2019; 26:110-120. [PMID: 30692646 DOI: 10.1038/s41594-018-0179-5] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 12/06/2018] [Indexed: 01/31/2023]
Abstract
The assembly of large multimeric complexes in the crowded cytoplasm is challenging. Here we reveal a mechanism that ensures accurate production of the yeast proteasome, involving ribosome pausing and co-translational assembly of Rpt1 and Rpt2. Interaction of nascent Rpt1 and Rpt2 then lifts ribosome pausing. We show that the N-terminal disordered domain of Rpt1 is required to ensure efficient ribosome pausing and association of nascent Rpt1 protein complexes into heavy particles, wherein the nascent protein complexes escape ribosome quality control. Immunofluorescence and in situ hybridization studies indicate that Rpt1- and Rpt2-encoding messenger RNAs co-localize in these particles that contain, and are dependent on, Not1, the scaffold of the Ccr4-Not complex. We refer to these particles as Not1-containing assemblysomes, as they are smaller than and distinct from other RNA granules such as stress granules and GW- or P-bodies. Synthesis of Rpt1 with ribosome pausing and Not1-containing assemblysome induction is conserved from yeast to human cells.
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41
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Reed RG, Tomko RJ. Engineered disulfide crosslinking to measure conformational changes in the 26S proteasome. Methods Enzymol 2019; 619:145-159. [PMID: 30910019 DOI: 10.1016/bs.mie.2018.11.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The 26S proteasome is a multisubunit ATP-dependent peptidase complex mediating most regulated protein degradation in eukaryotes. The proteasome undergoes several coordinated conformational changes during catalysis that activate it for substrate processing and functionally couple distinct enzymatic activities during substrate degradation. Understanding the impact of substrate interactions and individual ATP binding events on these conformational changes is currently a major bottleneck in the study of proteasome function. Here, we describe a simple biochemical reporter based on engineered disulfide crosslinking for measuring the conformational distribution of the Saccharomyces cerevisiae 26S proteasome. We demonstrate its use to investigate the impact of ATP analogs and proteasome inhibitors on proteasome conformational equilibria. This reporter allows simultaneous and rapid comparison of multiple treatments or conditions on the steady-state conformational distribution of the proteasome and can be readily extended to the study of other multisubunit complexes for which multiple conformational states are known at near-atomic resolution.
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Affiliation(s)
- Randi G Reed
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL, United States
| | - Robert J Tomko
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL, United States.
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42
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From Discovery to Bedside: Targeting the Ubiquitin System. Cell Chem Biol 2018; 26:156-177. [PMID: 30554913 DOI: 10.1016/j.chembiol.2018.10.022] [Citation(s) in RCA: 104] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Revised: 08/21/2018] [Accepted: 10/26/2018] [Indexed: 12/11/2022]
Abstract
The ubiquitin/proteasome system is a primary conduit for selective intracellular protein degradation. Since its discovery over 30 years ago, this highly regulated system continues to be an active research area for drug discovery that is exemplified by several approved drugs. Here we review compounds in preclinical testing, clinical trials, and approved drugs, with the aim of highlighting innovative discoveries and breakthrough therapies that target the ubiquitin system.
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43
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Ubiquitin-dependent switch during assembly of the proteasomal ATPases mediated by Not4 ubiquitin ligase. Proc Natl Acad Sci U S A 2018; 115:13246-13251. [PMID: 30530678 DOI: 10.1073/pnas.1805353115] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In the proteasome holoenzyme, the hexameric ATPases (Rpt1-Rpt6) enable degradation of ubiquitinated proteins by unfolding and translocating them into the proteolytic core particle. During early-stage proteasome assembly, individual Rpt proteins assemble into the hexameric "Rpt ring" through binding to their cognate chaperones: Nas2, Hsm3, Nas6, and Rpn14. Here, we show that Rpt ring assembly employs a specific ubiquitination-mediated control. An E3 ligase, Not4, selectively ubiquitinates Rpt5 during Rpt ring assembly. To access Rpt5, Not4 competes with Nas2 until the penultimate step and then with Hsm3 at the final step of Rpt ring completion. Using the known Rpt-chaperone cocrystal structures, we show that Not4-mediated ubiquitination sites in Rpt5 are obstructed by Nas2 and Hsm3. Thus, Not4 can distinguish a Rpt ring that matures without these chaperones, based on its accessibility to Rpt5. Rpt5 ubiquitination does not destabilize the ring but hinders incorporation of incoming subunits-Rpn1 ubiquitin receptor and Ubp6 deubiquitinase-thereby blocking progression of proteasome assembly and ubiquitin regeneration from proteasome substrates. Our findings reveal an assembly checkpoint where Not4 monitors chaperone actions during hexameric ATPase ring assembly, thereby ensuring the accuracy of proteasome holoenzyme maturation.
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44
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UBL domain of Usp14 and other proteins stimulates proteasome activities and protein degradation in cells. Proc Natl Acad Sci U S A 2018; 115:E11642-E11650. [PMID: 30487212 DOI: 10.1073/pnas.1808731115] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The best-known function of ubiquitin-like (UBL) domains in proteins is to enable their binding to 26S proteasomes. The proteasome-associated deubiquitinating enzyme Usp14/UBP6 contains an N-terminal UBL domain and is an important regulator of proteasomal activity. Usp14 by itself represses multiple proteasomal activities but, upon binding a ubiquitin chain, Usp14 stimulates these activities and promotes ubiquitin-conjugate degradation. Here, we demonstrate that Usp14's UBL domain alone mimics this activation of proteasomes by ubiquitin chains. Addition of this UBL domain to purified 26S proteasomes stimulated the same activities inhibited by Usp14: peptide entry and hydrolysis, protein-dependent ATP hydrolysis, deubiquitination by Rpn11, and the degradation of ubiquitinated and nonubiquitinated proteins. Thus, the binding of Usp14's UBL (apparently to Rpn1's T2 site) seems to mediate the activation of proteasomes by ubiquitinated substrates. However, the stimulation of these various activities was greater in proteasomes lacking Usp14 than in wild-type particles and thus is a general response that does not involve some displacement of Usp14. Furthermore, the UBL domains from hHR23 and hPLIC1/UBQLN1 also stimulated peptide hydrolysis, and the expression of hHR23A's UBL domain in HeLa cells stimulated overall protein degradation. Therefore, many UBL-containing proteins that bind to proteasomes may also enhance allosterically its proteolytic activity.
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45
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Lee D, Takayama S, Goldberg AL. ZFAND5/ZNF216 is an activator of the 26S proteasome that stimulates overall protein degradation. Proc Natl Acad Sci U S A 2018; 115:E9550-E9559. [PMID: 30254168 PMCID: PMC6187164 DOI: 10.1073/pnas.1809934115] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
ZFAND5/ZNF216, a member of the zinc finger AN1-type domain family, is abundant in heart and brain, but is induced in skeletal muscle during atrophy (although not in proteotoxic stress). Because mice lacking ZFAND5 exhibit decreased atrophy, a role in stimulating protein breakdown seemed likely. Addition of recombinant ZFAND5 to purified 26S proteasomes stimulated hydrolysis of ubiquitinated proteins, short peptides, and ATP. Mutating its C-terminal AN1 domain abolished the stimulation of proteasomal peptidase activity. Mutating its N-terminal zinc finger A20 domain, which binds ubiquitin chains, prevented the enhanced degradation of ubiquitinated proteins without affecting peptidase activity. Mouse embryonic fibroblast (MEF) cells lacking ZFAND5 had lower rates of protein degradation and proteasomal activity than WT MEFs. ZFAND5 addition to cell lysates stimulated proteasomal activity and protein degradation. Unlike other proteasome regulators, ZFAND5 enhances multiple 26S activities and overall cellular protein breakdown.
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Affiliation(s)
- Donghoon Lee
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115
| | | | - Alfred L Goldberg
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115;
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46
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Bertoni M, Aloy P. DynBench3D, a Web-Resource to Dynamically Generate Benchmark Sets of Large Heteromeric Protein Complexes. J Mol Biol 2018; 430:4431-4438. [PMID: 30274705 DOI: 10.1016/j.jmb.2018.09.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 08/21/2018] [Accepted: 09/11/2018] [Indexed: 11/24/2022]
Abstract
Multi-protein machines are responsible for most cellular tasks, and many efforts have been invested in the systematic identification and characterization of thousands of these macromolecular assemblies. However, unfortunately, the (quasi) atomic details necessary to understand their function are available only for a tiny fraction of the known complexes. The computational biology community is developing strategies to integrate structural data of different nature, from electron microscopy to X-ray crystallography, to model large molecular machines, as it has been done for individual proteins and interactions with remarkable success. However, unlike for binary interactions, there is no reliable gold-standard set of three-dimensional (3D) complexes to benchmark the performance of these methodologies and detect their limitations. Here, we present a strategy to dynamically generate non-redundant sets of 3D heteromeric complexes with three or more components. By changing the values of sequence identity and component overlap between assemblies required to define complex redundancy, we can create sets of representative complexes with known 3D structure (i.e., target complexes). Using an identity threshold of 20% and imposing a fraction of component overlap of <0.5, we identify 495 unique target complexes, which represent a real non-redundant set of heteromeric assemblies with known 3D structure. Moreover, for each target complex, we also identify a set of assemblies, of varying degrees of identity and component overlap, that can be readily used as input in a complex modeling exercise (i.e., template subcomplexes). We hope that resources like this will significantly help the development and progress assessment of novel methodologies, as docking benchmarks and blind prediction contests did. The interactive resource is accessible at https://DynBench3D.irbbarcelona.org.
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Affiliation(s)
- Martino Bertoni
- Joint IRB-BSC-CRG Program in Computational Biology, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Catalonia, Spain
| | - Patrick Aloy
- Joint IRB-BSC-CRG Program in Computational Biology, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Catalonia, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Catalonia, Spain.
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47
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Abstract
As the endpoint for the ubiquitin-proteasome system, the 26S proteasome is the principal proteolytic machine responsible for regulated protein degradation in eukaryotic cells. The proteasome's cellular functions range from general protein homeostasis and stress response to the control of vital processes such as cell division and signal transduction. To reliably process all the proteins presented to it in the complex cellular environment, the proteasome must combine high promiscuity with exceptional substrate selectivity. Recent structural and biochemical studies have shed new light on the many steps involved in proteasomal substrate processing, including recognition, deubiquitination, and ATP-driven translocation and unfolding. In addition, these studies revealed a complex conformational landscape that ensures proper substrate selection before the proteasome commits to processive degradation. These advances in our understanding of the proteasome's intricate machinery set the stage for future studies on how the proteasome functions as a major regulator of the eukaryotic proteome.
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Affiliation(s)
- Jared A M Bard
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA;
- California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, California 94720, USA
| | - Ellen A Goodall
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA;
- California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, California 94720, USA
| | - Eric R Greene
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA;
- California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, California 94720, USA
| | - Erik Jonsson
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA;
- California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, California 94720, USA
- Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, California 94720, USA
| | - Ken C Dong
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA;
- California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, California 94720, USA
- Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, California 94720, USA
| | - Andreas Martin
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA;
- California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, California 94720, USA
- Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, California 94720, USA
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48
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Snoberger A, Brettrager EJ, Smith DM. Conformational switching in the coiled-coil domains of a proteasomal ATPase regulates substrate processing. Nat Commun 2018; 9:2374. [PMID: 29915197 PMCID: PMC6006169 DOI: 10.1038/s41467-018-04731-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 05/18/2018] [Indexed: 12/15/2022] Open
Abstract
Protein degradation in all domains of life requires ATPases that unfold and inject proteins into compartmentalized proteolytic chambers. Proteasomal ATPases in eukaryotes and archaea contain poorly understood N-terminally conserved coiled-coil domains. In this study, we engineer disulfide crosslinks in the coiled-coils of the archaeal proteasomal ATPase (PAN) and report that its three identical coiled-coil domains can adopt three different conformations: (1) in-register and zipped, (2) in-register and partially unzipped, and (3) out-of-register. This conformational heterogeneity conflicts with PAN's symmetrical OB-coiled-coil crystal structure but resembles the conformational heterogeneity of the 26S proteasomal ATPases' coiled-coils. Furthermore, we find that one coiled-coil can be conformationally constrained even while unfolding substrates, and conformational changes in two of the coiled-coils regulate PAN switching between resting and active states. This switching functionally mimics similar states proposed for the 26S proteasome from cryo-EM. These findings thus build a mechanistic framework to understand regulation of proteasome activity.
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Affiliation(s)
- Aaron Snoberger
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, WV, 26506, USA
| | - Evan J Brettrager
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, WV, 26506, USA
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL, 26501, USA
| | - David M Smith
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, WV, 26506, USA.
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49
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Chen L, Zhu G, Johns EM, Yang X. TRIM11 activates the proteasome and promotes overall protein degradation by regulating USP14. Nat Commun 2018; 9:1223. [PMID: 29581427 PMCID: PMC5964324 DOI: 10.1038/s41467-018-03499-z] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 02/19/2018] [Indexed: 12/27/2022] Open
Abstract
The proteasome is a complex protease critical for protein quality control and cell regulation, and its dysfunction is associated with cancer and other diseases. However, the mechanisms that control proteasome activity in normal and malignant cells remain unclear. Here we report that TRIM11 enhances degradation of aberrant and normal regulatory proteins, and augments overall rate of proteolysis. Mechanistically, TRIM11 binds to both the proteasome and USP14, a deubiquitinase that prematurely removes ubiquitins from proteasome-bound substrates and also noncatalytically inhibits the proteasome, and precludes their association, thereby increasing proteasome activity. TRIM11 promotes cell survival and is upregulated upon heat shock. Moreover, TRIM11 is required for tumor growth, and increased expression of TRIM11 correlates with poor clinical survival. These findings identify TRIM11 as an important activator of the proteasome, define a pathway that adjusts proteasome activity, and reveal a mechanism by which tumor cells acquire higher degradative power to support oncogenic growth. The proteasome-bound ubiquitinase USP14 plays an important role in determining proteasome activity and substrate specificity. Here the authors show that TRIM11, a member of the mammalian tripartite motif family, regulates USP14 and is an important activator of the proteasome.
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Affiliation(s)
- Liang Chen
- Department of Cancer Biology and Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Guixin Zhu
- Department of Cancer Biology and Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Eleanor M Johns
- Department of Cancer Biology and Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Xiaolu Yang
- Department of Cancer Biology and Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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50
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Sun S, Liu S, Zhang Z, Zeng W, Sun C, Tao T, Lin X, Feng XH. Phosphatase UBLCP1 controls proteasome assembly. Open Biol 2018; 7:rsob.170042. [PMID: 28539385 PMCID: PMC5451543 DOI: 10.1098/rsob.170042] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 04/20/2017] [Indexed: 12/26/2022] Open
Abstract
Ubiquitin-like domain-containing C-terminal domain phosphatase 1 (UBLCP1), an FCP/SCP phosphatase family member, was identified as the first proteasome phosphatase. UBLCP1 binds to proteasome subunit Rpn1 and dephosphorylates the proteasome in vitro. However, it is still unclear which proteasome subunit(s) are the bona fide substrate(s) of UBLCP1 and the precise mechanism for proteasome regulation remains elusive. Here, we show that UBLCP1 selectively binds to the 19S regulatory particle (RP) through its interaction with Rpn1, but not the 20S core particle (CP) or the 26S proteasome holoenzyme. In the RP, UBLCP1 dephosphorylates the subunit Rpt1, impairs its ATPase activity, and consequently disrupts the 26S proteasome assembly, yet it has no effects on the RP assembly from precursor complexes. The Rpn1-binding and phosphatase activities of UBLCP1 are essential for its function on Rpt1 dephosphorylation and proteasome activity both in vivo and in vitro. Our study establishes the essential role of the UBLCP1/Rpn1/Rpt1 complex in regulating proteasome assembly.
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Affiliation(s)
- Shuangwu Sun
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Sisi Liu
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Zhengmao Zhang
- Michael E. DeBakey, Department of Surgery, Houston, TX, USA.,Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Wang Zeng
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Chuang Sun
- Michael E. DeBakey, Department of Surgery, Houston, TX, USA
| | - Tao Tao
- State Key Laboratory of Stress Cell Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, People's Republic of China
| | - Xia Lin
- Michael E. DeBakey, Department of Surgery, Houston, TX, USA.,Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Xin-Hua Feng
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China .,Michael E. DeBakey, Department of Surgery, Houston, TX, USA.,Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
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