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Yu ZQ, Carmichael J, Collins GA, D'Agostino MD, Lessard M, Firth HV, Harijan P, Fry AE, Dean J, Zhang J, Kini U, Goldberg AL, Rubinsztein DC. PSMC5 insufficiency and P320R mutation impair proteasome function. Hum Mol Genet 2024; 33:1506-1523. [PMID: 38776958 PMCID: PMC11336065 DOI: 10.1093/hmg/ddae085] [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: 02/21/2024] [Revised: 05/03/2024] [Accepted: 05/08/2024] [Indexed: 05/25/2024] Open
Abstract
The ubiquitin-proteasome system mediates the degradation of a wide variety of proteins. Proteasome dysfunction is associated with neurodegenerative diseases and neurodevelopmental disorders in humans. Here we identified mutations in PSMC5, an AAA ATPase subunit of the proteasome 19S regulatory particle, in individuals with neurodevelopmental disorders, which were initially considered as variants of unknown significance. We have now found heterozygotes with the following mutations: P320R (6 individuals), R325W, Q160A, and one nonsense mutation at Q69. We focused on understanding the functional consequence of PSMC5 insufficiency and the P320R mutation in cells and found that both impair proteasome function and activate apoptosis. Interestingly, the P320R mutation impairs proteasome function by weakening the association between the 19S regulatory particle and the 20S core particle. Our study supports that proteasome dysfunction is the pathogenic cause of neurodevelopmental disorders in individuals carrying PSMC5 variants.
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Affiliation(s)
- Zhong-Qiu Yu
- Cambridge Institute for Medical Research, The Keith Peters Building, Department of Medical Genetics, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, United Kingdom
- UK Dementia Research Institute, University of Cambridge, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, United Kingdom
| | - Jenny Carmichael
- Department of Clinical Genetics, Cambridge University Hospitals NHS Foundation Trust, Box 134, Addenbrooke’s Hospital, Cambridge CB2 0QQ, United Kingdom
| | - Galen A Collins
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, United States
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, 32 Creelman Street, Starkville MS 39762, United States
| | - Maria Daniela D'Agostino
- Division of Medical Genetics, Department of Specialised Medicine, McGill University Health Centre, 1001 Decarie Boulevard, Montreal, Quebec, H4A 3J1, Canada
- Care for Rare Canada Consortium, Children’s Hospital of Eastern Ontario Research Institute, 401 Smyth Road, Ottawa, K1H 8L1, ON, Canada
| | - Mathieu Lessard
- Division of Medical Genetics, Department of Specialised Medicine, McGill University Health Centre, 1001 Decarie Boulevard, Montreal, Quebec, H4A 3J1, Canada
- Care for Rare Canada Consortium, Children’s Hospital of Eastern Ontario Research Institute, 401 Smyth Road, Ottawa, K1H 8L1, ON, Canada
| | - Helen V Firth
- Department of Clinical Genetics, Cambridge University Hospitals NHS Foundation Trust, Box 134, Addenbrooke’s Hospital, Cambridge CB2 0QQ, United Kingdom
| | - Pooja Harijan
- Department of Paediatric Neurosciences, Box 107, Child development centre, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 0QQ, United Kingdom
| | - Andrew E Fry
- All Wales Medical Genomics Service, University Hospital of Wales, Heath Park, Cardiff CF14 4XW, United Kingdom
- Division of Cancer and Genetics, Cardiff University, Heath Park, Cardiff CF14 4XN, United Kingdom
| | - John Dean
- The School of Medicine, Medical Sciences and Nutrition, Polwarth Building, University of Aberdeen, Aberdeen, AB25 2ZD, United Kingdom
| | - Jiuchun Zhang
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, United States
| | - Usha Kini
- Oxford Centre for Genomic Medicine, Oxford University Hospitals NHS Foundation Trust, Oxford & Radcliffe Department of Medicine, University of Oxford, Windmill Road, Oxford, OX3 7HE, United Kingdom
| | - Alfred L Goldberg
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, United States
| | - David C Rubinsztein
- Cambridge Institute for Medical Research, The Keith Peters Building, Department of Medical Genetics, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, United Kingdom
- UK Dementia Research Institute, University of Cambridge, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, United Kingdom
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2
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Wang J, Kjellgren A, DeMartino GN. Differential Interactions of the Proteasome Inhibitor PI31 with Constitutive and Immuno-20S Proteasomes. Biochemistry 2024; 63:1000-1015. [PMID: 38577872 DOI: 10.1021/acs.biochem.3c00707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2024]
Abstract
PI31 (Proteasome Inhibitor of 31,000 Da) is a 20S proteasome binding protein originally identified as an in vitro inhibitor of 20S proteasome proteolytic activity. Recently reported cryo-electron microscopy structures of 20S-PI31 complexes have revealed that the natively disordered proline-rich C-terminus of PI31 enters the central chamber in the interior of the 20S proteasome and interacts directly with the proteasome's multiple catalytic threonine residues in a manner predicted to inhibit their enzymatic function while evading its own proteolysis. Higher eukaryotes express an alternative form of the 20S proteasome (termed "immuno-proteasome") that features genetically and functionally distinct catalytic subunits. The effect of PI31 on immuno-proteasome function is unknown. We examine the relative inhibitory effects of PI31 on purified constitutive (20Sc) and immuno-(20Si) 20S proteasomes in vitro and show that PI31 inhibits 20Si hydrolytic activity to a significantly lesser degree than that of 20Sc. Unlike 20Sc, 20Si hydrolyzes the carboxyl-terminus of PI31 and this effect contributes to the reduced inhibitory activity of PI31 toward 20Si. Conversely, loss of 20Sc inhibition by PI31 point mutants leads to PI31 degradation by 20Sc. These results demonstrate unexpected differential interactions of PI31 with 20Sc and 20Si and document their functional consequences.
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Affiliation(s)
- Jason Wang
- Department of Physiology, UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas 75390-9040, United States
| | - Abbey Kjellgren
- Department of Physiology, UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas 75390-9040, United States
| | - George N DeMartino
- Department of Physiology, UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas 75390-9040, United States
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3
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PKR Protects the Major Catalytic Subunit of PKA Cpk1 from FgBlm10-Mediated Proteasome Degradation in Fusarium graminearum. Int J Mol Sci 2022; 23:ijms231810208. [PMID: 36142119 PMCID: PMC9499325 DOI: 10.3390/ijms231810208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 08/31/2022] [Accepted: 09/02/2022] [Indexed: 11/17/2022] Open
Abstract
For optimal proteolytic function, the proteasome core (CP or 20S) must associate with activators. The cAMP-PKA pathway is reported to affect the activity of the proteasome in humans. However, the relationship between the proteasome and PKA is not well characterized. Our results showed that the major catalytic subunit Cpk1 was degraded without the protection of Pkr. Eleven (out of 67) pkr suppressors had FgBlm10 C-terminal truncation, one suppressor had an amino acid change mutation in the PRE6 ortholog (FGRRES_07282), and one in the PRE5 ortholog (FGRRES_05222). These mutations rescued the defects in growth and conidial morphology, Cpk1 stability, and PKA activities in the pkr mutant. The interaction of FgBlm10 with FgPre5 and FgPre6 were detected by co-immunoprecipitation, and the essential elements for their interaction were characterized, including the FgBlm10 C-terminus, amino acid D82 of FgPre6 and K62 of FgPre5. Additional FgBlm10-interacting proteins were identified in the wild type and pkr mutant, suggesting that PKA regulates the preference of FgBlm10-mediated proteasome assembly. In addition, PKA indirectly affected the phosphorylation of FgBlm10, and its localization in the nucleus. The truncation of the FgBlm10 C terminus also enhanced nuclear import and bleomycin resistance, suggesting its role in proteasome assembly at DNA damage sites. Collectively, our data demonstrated that regulation between PKA and proteasome degradation is critical for the vegetative growth of F. graminearum.
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Yazgili AS, Ebstein F, Meiners S. The Proteasome Activator PA200/PSME4: An Emerging New Player in Health and Disease. Biomolecules 2022; 12:1150. [PMID: 36009043 PMCID: PMC9406137 DOI: 10.3390/biom12081150] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Revised: 08/17/2022] [Accepted: 08/18/2022] [Indexed: 11/24/2022] Open
Abstract
Proteasomes comprise a family of proteasomal complexes essential for maintaining protein homeostasis. Accordingly, proteasomes represent promising therapeutic targets in multiple human diseases. Several proteasome inhibitors are approved for treating hematological cancers. However, their side effects impede their efficacy and broader therapeutic applications. Therefore, understanding the biology of the different proteasome complexes present in the cell is crucial for developing tailor-made inhibitors against specific proteasome complexes. Here, we will discuss the structure, biology, and function of the alternative Proteasome Activator 200 (PA200), also known as PSME4, and summarize the current evidence for its dysregulation in different human diseases. We hereby aim to stimulate research on this enigmatic proteasome regulator that has the potential to serve as a therapeutic target in cancer.
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Affiliation(s)
- Ayse Seda Yazgili
- Comprehensive Pneumology Center (CPC), Helmholtz Center Munich, Max-Lebsche Platz 31, 81377 Munich, Germany
| | - Frédéric Ebstein
- Institut für Medizinische Biochemie und Molekularbiologie (IMBM), Universitätsmedizin Greifswald, Ferdinand-Sauerbruch-Straße, Klinikum DZ/7, 17475 Greifswald, Germany
| | - Silke Meiners
- Research Center Borstel/Leibniz Lung Center, Parkallee 1-40, 23845 Borstel, Germany
- Airway Research Center North (ARCN), German Center for Lung Research (DZL), 23845 Sülfeld, Germany
- Institute of Experimental Medicine, Christian-Albrechts University Kiel, 24118 Kiel, Germany
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5
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Khan SU, Khan MU, Kalsoom F, Khan MI, Gao S, Unar A, Zubair M, Bilal M. Mechanisms of gene regulation by histone degradation in adaptation of yeast: an overview of recent advances. Arch Microbiol 2022; 204:287. [PMID: 35482104 DOI: 10.1007/s00203-022-02897-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 03/12/2022] [Accepted: 04/04/2022] [Indexed: 02/07/2023]
Abstract
Histones are important component of eukaryotic cells chromatin and consist of arginine and lysine residues. Histones play an important role in the protection of DNA. Their contents significantly affect high-level chromatin structure formation, gene expression, DNA replication, and other important life activities. Protein degradation is an important regulatory mechanism of histone content. Recent studies have revealed that modification of amino acid sequence is directly related to histone breakdown. In addition, histone degradation is closely related to covalent modifications, such as ubiquitination and acetylation, which are considered to be driving factors in gene regulation. Gene regulation is an important mechanism in adaptation to the environment and survival of species. With the introduction of highly efficient technology, various mutations in histones have been identified in yeast. In the field of epigenetics and the transmission of chromatin states, two widely used model organisms are the budding yeast Saccharomyces cerevisiae and Schizosaccharomyces pombe. Higher eukaryotes can use their silent loci to maintain their epigenetic states and providing the base to investigate mechanisms underlying development. Therfore, both species have contributed a plethora of information on these mechanisms in both yeast and higher eukaryotes. This study focuses on the role of histone modifications in controlling telomeric silencing in Saccharomyces cerevisiae and centromeric silencing in S. pombe as examples of genetic loci that demonstrate epigenetic inheritance. In view of recent advances, this review focuses on the post-translational modification of histone amino acid residues and reviews the relationship between histone degradation and amino acid residue modification.
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Affiliation(s)
- Safir Ullah Khan
- Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, 230027, People's Republic of China
| | - Munir Ullah Khan
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, 310027, People's Republic of China
| | - Fadia Kalsoom
- Department of Microbiology, Ajou University School of Medicine, Suwon, 16499, Republic of Korea
| | - Muhammad Imran Khan
- School of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230027, People's Republic of China.
- Hefei National Laboratory for Physical Sciences at Microscale and the Center for Biomedical Engineering, University of Science and Technology of China, Hefei, 230027, People's Republic of China.
- Department of Pathology, District headquarters hospital, Jhang, 35200, Punjab Province, Islamic Republic of Pakistan.
| | - Shuang Gao
- School of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230027, People's Republic of China
| | - Ahsanullah Unar
- School of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230027, People's Republic of China
| | - Muhammad Zubair
- School of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230027, People's Republic of China
- The First Affiliated Hospital of USTC, Hefei National Laboratory for Physical Sciences at Microscale, School of Basic Medical Sciences, University of Science and Technology of China, Hefei, 230027, People's Republic of China
| | - Muhammad Bilal
- School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian, 223003, People's Republic of China.
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6
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Functional Differences between Proteasome Subtypes. Cells 2022; 11:cells11030421. [PMID: 35159231 PMCID: PMC8834425 DOI: 10.3390/cells11030421] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/11/2022] [Accepted: 01/14/2022] [Indexed: 12/30/2022] Open
Abstract
Four proteasome subtypes are commonly present in mammalian tissues: standard proteasomes, which contain the standard catalytic subunits β1, β2 and β5; immunoproteasomes containing the immuno-subunits β1i, β2i and β5i; and two intermediate proteasomes, containing a mix of standard and immuno-subunits. Recent studies revealed the expression of two tissue-specific proteasome subtypes in cortical thymic epithelial cells and in testes: thymoproteasomes and spermatoproteasomes. In this review, we describe the mechanisms that enable the ATP- and ubiquitin-dependent as well as the ATP- and ubiquitin-independent degradation of proteins by the proteasome. We focus on understanding the role of the different proteasome subtypes in maintaining protein homeostasis in normal physiological conditions through the ATP- and ubiquitin-dependent degradation of proteins. Additionally, we discuss the role of each proteasome subtype in the ATP- and ubiquitin-independent degradation of disordered proteins. We also discuss the role of the proteasome in the generation of peptides presented by MHC class I molecules and the implication of having different proteasome subtypes for the peptide repertoire presented at the cell surface. Finally, we discuss the role of the immunoproteasome in immune cells and its modulation as a potential therapy for autoimmune diseases.
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7
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Reboud-Ravaux M. [The proteasome - structural aspects and inhibitors: a second life for a validated drug target]. Biol Aujourdhui 2021; 215:1-23. [PMID: 34397372 DOI: 10.1051/jbio/2021005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Indexed: 02/06/2023]
Abstract
The proteasome is the central component of the adaptable ubiquitin proteasome system (UPS) discovered in the 1980's. It sustains protein homeostasis (proteostasis) under a large variety of physiological and pathological conditions. Its dysregulation has been often associated to various human diseases. Its potential regulation by modulators has emerged as promising avenue to develop treatments of various pathologies. The FDA approval in 2003 of the proteasome inhibitor bortezomib to treat multiple myeloma, then mantle lymphoma in 2006, has considerably increased the clinical interest of proteasome inhibition. Second-generation proteasome inhibitors (carfilzomib and ixazomib) have been approved to overcome bortezomib resistance and improved toxicity profile and route of administration. Selective inhibition of immunoproteasome is a promising approach towards the development of immunomodulatory drugs. The design of these drugs relies greatly on the elucidation of high-resolution structures of the targeted proteasomes. The ATPase-dependent 26S proteasome (2.4 MDa) consists of a 20S proteolytic core and one or two 19S regulatory particles. The 20S core contains three types of catalytic sites. In recent years, due to technical advances especially in atomic cryo-electron microscopy, significant progress has been made in the understanding of 26S proteasome structure and its dynamics. Stepwise conformational changes of the 19S particle induced by ATP hydrolysis lead to substrate translocation, 20S pore opening and processive protein degradation by the 20S proteolytic subunits (2β1, 2β2 and 2β5). A large variety of structurally different inhibitors, both natural products or synthetic compounds targeting immuno- and constitutive proteasomes, has been discovered. The latest advances in this drug discovery are presented. Knowledge about structures, inhibition mechanism and detailed biological regulations of proteasomes can guide strategies for the development of next-generation inhibitors to treat human diseases, especially cancers, immune disorders and pathogen infections. Proteasome activators are also potentially applicable to the reduction of proteotoxic stresses in neurodegeneration and aging.
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Affiliation(s)
- Michèle Reboud-Ravaux
- Sorbonne Université, Institut de Biologie Paris Seine (IBPS), CNRS UMR 8256, Inserm ERL U1164, 7 quai Saint Bernard, 75252 Paris Cedex 05, France
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8
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The proteasome and its role in the nervous system. Cell Chem Biol 2021; 28:903-917. [PMID: 33905676 DOI: 10.1016/j.chembiol.2021.04.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 03/04/2021] [Accepted: 04/05/2021] [Indexed: 12/14/2022]
Abstract
Proteasomes are multisubunit complexes that catalyze the majority of protein degradation in mammalian cells to maintain protein homeostasis and influence the regulation of most cellular processes. The proteasome, a multicatalytic protease complex, is a ring-like structure with a narrow pore that exhibits regulated gating, enabling the selective degradation of target proteins into peptide fragments. This process of removing proteins is essential for eliminating proteins that are no longer wanted, such as unfolded or aggregated proteins. This is important for preserving cellular function relevant to brain health and disease. Recently, in the nervous system, specialized proteasomes have been shown to generate peptides with important cellular functions. These discoveries challenge the prevailing notion that proteasomes primarily operate to eliminate proteins and identify signaling-competent proteasomes. This review focuses on the structure, function, and regulation of proteasomes and sheds light on emerging areas of investigation regarding the role of proteasomes in the nervous system.
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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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10
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Quinet G, Gonzalez-Santamarta M, Louche C, Rodriguez MS. Mechanisms Regulating the UPS-ALS Crosstalk: The Role of Proteaphagy. Molecules 2020; 25:E2352. [PMID: 32443527 PMCID: PMC7288101 DOI: 10.3390/molecules25102352] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Revised: 05/14/2020] [Accepted: 05/16/2020] [Indexed: 12/18/2022] Open
Abstract
Protein degradation is tightly regulated inside cells because of its utmost importance for protein homeostasis (proteostasis). The two major intracellular proteolytic pathways are the ubiquitin-proteasome and the autophagy-lysosome systems which ensure the fate of proteins when modified by various members of the ubiquitin family. These pathways are tightly interconnected by receptors and cofactors that recognize distinct chain architectures to connect with either the proteasome or autophagy under distinct physiologic and pathologic situations. The degradation of proteasome by autophagy, known as proteaphagy, plays an important role in this crosstalk since it favours the activity of autophagy in the absence of fully active proteasomes. Recently described in several biological models, proteaphagy appears to help the cell to survive when proteostasis is broken by the absence of nutrients or the excess of proteins accumulated under various stress conditions. Emerging evidence indicates that proteaphagy could be permanently activated in some types of cancer or when chemoresistance is observed in patients.
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Affiliation(s)
| | | | | | - Manuel S. Rodriguez
- ITAV-CNRS USR 3505 IPBS-UPS, 1 Place Pierre Potier, 31106 Toulouse, France; (G.Q.); (M.G.-S.); (C.L.)
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11
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Osmulski PA, Karpowicz P, Jankowska E, Bohmann J, Pickering AM, Gaczyńska M. New Peptide-Based Pharmacophore Activates 20S Proteasome. Molecules 2020; 25:E1439. [PMID: 32235805 PMCID: PMC7145288 DOI: 10.3390/molecules25061439] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 03/13/2020] [Accepted: 03/18/2020] [Indexed: 02/01/2023] Open
Abstract
The proteasome is a pivotal element of controlled proteolysis, responsible for the catabolic arm of proteostasis. By inducing apoptosis, small molecule inhibitors of proteasome peptidolytic activities are successfully utilized in treatment of blood cancers. However, the clinical potential of proteasome activation remains relatively unexplored. In this work, we introduce short TAT peptides derived from HIV-1 Tat protein and modified with synthetic turn-stabilizing residues as proteasome agonists. Molecular docking and biochemical studies point to the α1/α2 pocket of the core proteasome α ring as the binding site of TAT peptides. We postulate that the TATs' pharmacophore consists of an N-terminal basic pocket-docking "activation anchor" connected via a β turn inducer to a C-terminal "specificity clamp" that binds on the proteasome α surface. By allosteric effects-including destabilization of the proteasomal gate-the compounds substantially augment activity of the core proteasome in vitro. Significantly, this activation is preserved in the lysates of cultured cells treated with the compounds. We propose that the proteasome-stimulating TAT pharmacophore provides an attractive lead for future clinical use.
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Affiliation(s)
- Paweł A. Osmulski
- Department of Molecular Medicine, UT Health San Antonio, Texas, TX 78245, USA;
- Barshop Institute for Longevity and Aging Studies, UT Health San Antonio, Texas, TX 78245, USA
| | - Przemysław Karpowicz
- Department of Organic Chemistry, Faculty of Chemistry, University of Gdansk, 80-308 Gdansk, Poland;
- Department of Biomedical Chemistry, Faculty of Chemistry, University of Gdansk, 80-308 Gdansk, Poland;
| | - Elżbieta Jankowska
- Department of Biomedical Chemistry, Faculty of Chemistry, University of Gdansk, 80-308 Gdansk, Poland;
| | - Jonathan Bohmann
- Southwest Research Institute, San Antonio, Texas, TX 78238, USA;
| | - Andrew M. Pickering
- Department of Molecular Medicine, UT Health San Antonio, Texas, TX 78245, USA;
- Barshop Institute for Longevity and Aging Studies, UT Health San Antonio, Texas, TX 78245, USA
- The Glenn Biggs Institute for Alzheimer’s & Neurodegenerative Diseases, UT Health San Antonio, TX 78229, USA
| | - Maria Gaczyńska
- Department of Molecular Medicine, UT Health San Antonio, Texas, TX 78245, USA;
- Barshop Institute for Longevity and Aging Studies, UT Health San Antonio, Texas, TX 78245, USA
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12
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Cryo-EM structures of the human PA200 and PA200-20S complex reveal regulation of proteasome gate opening and two PA200 apertures. PLoS Biol 2020; 18:e3000654. [PMID: 32134919 PMCID: PMC7077846 DOI: 10.1371/journal.pbio.3000654] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 03/17/2020] [Accepted: 02/21/2020] [Indexed: 12/30/2022] Open
Abstract
Proteasomes are highly abundant and conserved protease complexes that eliminate unwanted proteins in the cells. As a single-chain ATP-independent nuclear proteasome activator, proteasome activator 200 (PA200) associates with 20S core particle to form proteasome complex that catalyzes polyubiquitin-independent degradation of acetylated histones, thus playing a pivotal role in DNA repair and spermatogenesis. Here, we present cryo–electron microscopy (cryo-EM) structures of the human PA200-20S complex and PA200 at 2.72 Å and 3.75 Å, respectively. PA200 exhibits a dome-like architecture that caps 20S and uses its C-terminal YYA (Tyr-Tyr-Ala) to induce the α-ring rearrangements and partial opening of the 20S gate. Our structural data also indicate that PA200 has two openings formed by numerous positively charged residues that respectively bind (5,6)-bisdiphosphoinositol tetrakisphosphate (5,6[PP]2-InsP4) and inositol hexakisphosphate (InsP6) and are likely to be the gates that lead unfolded proteins through PA200 and into the 20S. Besides, our structural analysis of PA200 found that the bromodomain (BRD)-like (BRDL) domain of PA200 shows considerable sequence variation in comparison to other human BRDs, as it contains only 82 residues because of a short ZA loop, and cannot be classified into any of the eight typical human BRD families. Taken together, the results obtained from this study provide important insights into human PA200-induced 20S gate opening for substrate degradation and the opportunities to explore the mechanism for its recognition of H4 histone in acetylation-mediated proteasomal degradation. Proteasomes are highly abundant and conserved protease complexes that eliminate unwanted proteins in the cells. The cryo-EM structures of PA200 and the PA200-20S proteasome complex reveal two openings on PA200 which bind inositol phosphates as cofactors, and novel insights into PA200-induced gate-opening of 20S.
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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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14
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Giletto MB, Osmulski PA, Jones CL, Gaczynska ME, Tepe JJ. Pipecolic esters as minimized templates for proteasome inhibition. Org Biomol Chem 2020; 17:2734-2746. [PMID: 30778435 DOI: 10.1039/c9ob00122k] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Allosteric regulators of clinically important enzymes are gaining popularity as alternatives to competitive inhibitors. This is also the case for the proteasome, a major intracellular protease and a target of anti-cancer drugs. All clinically used proteasome inhibitors bind to the active sites in catalytic chamber and display a competitive mechanism. Unfortunately, inevitable resistance associated with this type of inhibition drives the search for non-competitive agents. The multisubunit and multicatalytic "proteolytic machine" such as the proteasome is occasionally found to be affected by agents with other primary targets. For example the immunosuppressive agent rapamycin has been shown to allosterically inhibit the proteasome albeit at levels far higher than its mTOR related efficacy. As part of an ongoing program to search for novel proteasome-targeting pharmacophores, we identified the binding domain of rapamycin as required for proteasome inhibition even without the macrocyclic context of the parent compound. By subsequent structure-activity relationship studies, we generated a pipecolic ester derivative compound 3 representing a new class of proteasome inhibitors. Compound 3 affects the core proteasome activities and proliferation of cancer cells with low micromolar/high nanomolar efficacy. Molecular modeling, atomic force microscopy imaging and biochemical data suggest that compound 3 binds into one of intersubunit pockets in the proteasomal α ring and destabilizes the α face and the gate. The α face is used as a docking area for proteasome-regulating protein modules and the gate is critical for controlling access to the catalytic chamber. Thus, the pipecolic ester template elicits a new and attractive mechanism for proteasome inhibition distinct from classical competitive drugs.
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Affiliation(s)
- Matthew B Giletto
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA.
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Coux O, Zieba BA, Meiners S. The Proteasome System in Health and Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1233:55-100. [DOI: 10.1007/978-3-030-38266-7_3] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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16
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Welk V, Meul T, Lukas C, Kammerl IE, Mulay SR, Schamberger AC, Semren N, Fernandez IE, Anders HJ, Günther A, Behr J, Eickelberg O, Korfei M, Meiners S. Proteasome activator PA200 regulates myofibroblast differentiation. Sci Rep 2019; 9:15224. [PMID: 31645612 PMCID: PMC6811633 DOI: 10.1038/s41598-019-51665-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 09/27/2019] [Indexed: 02/06/2023] Open
Abstract
The proteasome is essential for the selective degradation of most cellular proteins and is fine-tuned according to cellular needs. Proteasome activators serve as building blocks to adjust protein turnover in cell growth and differentiation. Understanding the cellular function of proteasome activation in more detail offers a new strategy for therapeutic targeting of proteasomal protein breakdown in disease. The role of the proteasome activator PA200 in cell function and its regulation in disease is unknown. In this study, we investigated the function of PA200 in myofibroblast differentiation and fibrotic tissue remodeling. PA200 was upregulated in hyperplastic basal cells and myofibroblasts of fibrotic lungs from patients with idiopathic pulmonary fibrosis. Increased expression of PA200 and enhanced formation of PA200-proteasome complexes was also evident in experimental fibrosis of the lung and kidney in vivo and in activated primary human myofibroblasts of the lung in vitro. Transient silencing and overexpression revealed that PA200 functions as a negative regulator of myofibroblast differentiation of human but not mouse cells. Our data thus suggest an unexpected and important role for PA200 in adjusting myofibroblast activation in response to pro-fibrotic stimuli, which fails in idiopathic pulmonary fibrosis.
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Affiliation(s)
- Vanessa Welk
- Comprehensive Pneumology Center (CPC), University Hospital of the Ludwig-Maximilians-University (LMU) and Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Max-Lebsche Platz 31, 81377, Munich, Germany
| | - Thomas Meul
- Comprehensive Pneumology Center (CPC), University Hospital of the Ludwig-Maximilians-University (LMU) and Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Max-Lebsche Platz 31, 81377, Munich, Germany
| | - Christina Lukas
- Comprehensive Pneumology Center (CPC), University Hospital of the Ludwig-Maximilians-University (LMU) and Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Max-Lebsche Platz 31, 81377, Munich, Germany
| | - Ilona E Kammerl
- Comprehensive Pneumology Center (CPC), University Hospital of the Ludwig-Maximilians-University (LMU) and Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Max-Lebsche Platz 31, 81377, Munich, Germany
| | - Shrikant R Mulay
- Division of Nephrology, Medizinische Klinik und Poliklinik IV, Klinikum der Universität, Ziemssenstraße 1, 80336, Munich, Germany
| | - Andrea C Schamberger
- Comprehensive Pneumology Center (CPC), University Hospital of the Ludwig-Maximilians-University (LMU) and Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Max-Lebsche Platz 31, 81377, Munich, Germany.,Translational Lung Research and CPC-M bioArchive, Helmholtz Zentrum München, Comprehensive Pneumology Center Munich DZL/CPC-M, Munich, Germany
| | - Nora Semren
- Comprehensive Pneumology Center (CPC), University Hospital of the Ludwig-Maximilians-University (LMU) and Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Max-Lebsche Platz 31, 81377, Munich, Germany
| | - Isis E Fernandez
- Comprehensive Pneumology Center (CPC), University Hospital of the Ludwig-Maximilians-University (LMU) and Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Max-Lebsche Platz 31, 81377, Munich, Germany.,Translational Lung Research and CPC-M bioArchive, Helmholtz Zentrum München, Comprehensive Pneumology Center Munich DZL/CPC-M, Munich, Germany
| | - Hans-Joachim Anders
- Division of Nephrology, Medizinische Klinik und Poliklinik IV, Klinikum der Universität, Ziemssenstraße 1, 80336, Munich, Germany
| | - Andreas Günther
- Department of Internal Medicine, Universities of Giessen and Marburg Lung Center (UGMLC), Justus-Liebig-University Giessen, Member of the German Center for Lung Research (DZL), Giessen, Germany.,European IPF Network and European IPF Registry, Giessen, Germany
| | - Jürgen Behr
- Comprehensive Pneumology Center (CPC), University Hospital of the Ludwig-Maximilians-University (LMU) and Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Max-Lebsche Platz 31, 81377, Munich, Germany.,Asklepios Fachkliniken München-Gauting, Gauting, Germany.,Medizinische Klinik und Poliklinik V, Klinikum der Ludwig-Maximilians-Universität, Member of the DZL, Munich, Germany
| | - Oliver Eickelberg
- Comprehensive Pneumology Center (CPC), University Hospital of the Ludwig-Maximilians-University (LMU) and Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Max-Lebsche Platz 31, 81377, Munich, Germany.,Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado, 12605 E. 16th Ave, Aurora, CO, 80045, United States
| | - Martina Korfei
- Department of Internal Medicine, Universities of Giessen and Marburg Lung Center (UGMLC), Justus-Liebig-University Giessen, Member of the German Center for Lung Research (DZL), Giessen, Germany
| | - Silke Meiners
- Comprehensive Pneumology Center (CPC), University Hospital of the Ludwig-Maximilians-University (LMU) and Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Max-Lebsche Platz 31, 81377, Munich, Germany.
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Toste Rêgo A, da Fonseca PCA. Characterization of Fully Recombinant Human 20S and 20S-PA200 Proteasome Complexes. Mol Cell 2019; 76:138-147.e5. [PMID: 31473102 PMCID: PMC6863390 DOI: 10.1016/j.molcel.2019.07.014] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 05/27/2019] [Accepted: 07/10/2019] [Indexed: 12/31/2022]
Abstract
Proteasomes are essential in all eukaryotic cells. However, their function and regulation remain considerably elusive, particularly those of less abundant variants. We demonstrate the human 20S proteasome recombinant assembly and confirmed the recombinant complex integrity biochemically and with a 2.6 Å resolution cryo-EM map. To assess its competence to form higher-order assemblies, we prepared and analyzed recombinant human 20S-PA200, a poorly characterized nuclear complex. Its 3.0 Å resolution cryo-EM structure reveals the PA200 unique architecture; the details of its intricate interactions with the proteasome, resulting in unparalleled proteasome α ring rearrangements; and the molecular basis for PA200 allosteric modulation of the proteasome active sites. Non-protein cryo-EM densities could be assigned to PA200-bound inositol phosphates, and we speculate regarding their functional role. Here we open extensive opportunities to study the fundamental properties of the diverse and distinct eukaryotic proteasome variants and to improve proteasome targeting under different therapeutic conditions. Recombinant human 20S proteasomes and 20S-PA200 complexes are characterized Cryo-EM reveals intricate 20S-PA200 interactions and PA200-bound cofactors PA200 binding is allosterically communicated to the proteolytic active sites Basis to fully characterize the function and regulation of proteasome variants
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Affiliation(s)
- Ana Toste Rêgo
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Paula C A da Fonseca
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
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18
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Morozov AV, Karpov VL. Proteasomes and Several Aspects of Their Heterogeneity Relevant to Cancer. Front Oncol 2019; 9:761. [PMID: 31456945 PMCID: PMC6700291 DOI: 10.3389/fonc.2019.00761] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 07/29/2019] [Indexed: 01/19/2023] Open
Abstract
The life of every organism is dependent on the fine-tuned mechanisms of protein synthesis and breakdown. The degradation of most intracellular proteins is performed by the ubiquitin proteasome system (UPS). Proteasomes are central elements of the UPS and represent large multisubunit protein complexes directly responsible for the protein degradation. Accumulating data indicate that there is an intriguing diversity of cellular proteasomes. Different proteasome forms, containing different subunits and attached regulators have been described. In addition, proteasomes specific for a particular tissue were identified. Cancer cells are highly dependent on the proper functioning of the UPS in general, and proteasomes in particular. At the same time, the information regarding the role of different proteasome forms in cancer is limited. This review describes the functional and structural heterogeneity of proteasomes, their association with cancer as well as several established and novel proteasome-directed therapeutic strategies.
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Affiliation(s)
- Alexey V. Morozov
- Laboratory of Regulation of Intracellular Proteolysis, W.A. Engelhardt Institute of Molecular Biology RAS, Moscow, Russia
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19
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Kravchuk OI, Lyupina YV, Erokhov PA, Finoshin AD, Adameyko KI, Mishyna MY, Moiseenko AV, Sokolova OS, Orlova OV, Beljelarskaya SN, Serebryakova MV, Indeykina MI, Bugrova AE, Kononikhin AS, Mikhailov VS. Characterization of the 20S proteasome of the lepidopteran, Spodoptera frugiperda. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2019; 1867:840-853. [PMID: 31228587 DOI: 10.1016/j.bbapap.2019.06.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 06/05/2019] [Accepted: 06/17/2019] [Indexed: 02/08/2023]
Abstract
Multiple complexes of 20S proteasomes with accessory factors play an essential role in proteolysis in eukaryotic cells. In this report, several forms of 20S proteasomes from extracts of Spodoptera frugiperda (Sf9) cells were separated using electrophoresis in a native polyacrylamide gel and examined for proteolytic activity in the gel and by Western blotting. Distinct proteasome bands isolated from the gel were subjected to liquid chromatography-tandem mass spectrometry and identified as free core particles (CP) and complexes of CP with one or two dimers of assembly chaperones PAC1-PAC2 and activators PA28γ or PA200. In contrast to the activators PA28γ and PA200 that regulate the access of protein substrates to the internal proteolytic chamber of CP in an ATP-independent manner, the 19S regulatory particle (RP) in 26S proteasomes performs stepwise substrate unfolding and opens the chamber gate in an ATP-dependent manner. Electron microscopic analysis suggested that spontaneous dissociation of RP in isolated 26S proteasomes leaves CPs with different gate sizes related presumably to different stages in the gate opening. The primary structure of 20S proteasome subunits in Sf9 cells was determined by a search of databases and by sequencing. The protein sequences were confirmed by mass spectrometry and verified by 2D gel electrophoresis. The relative rates of sequence divergence in the evolution of 20S proteasome subunits, the assembly chaperones and activators were determined by using bioinformatics. The data confirmed the conservation of regular CP subunits and PA28γ, a more accelerated evolution of PAC2 and PA200, and especially high divergence rates of PAC1.
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Affiliation(s)
- Oksana I Kravchuk
- N.K. Koltzov Institute of Developmental Biology, Russian Academy of Sciences, 26 Vavilova str., Moscow 119334, Russia
| | - Yulia V Lyupina
- N.K. Koltzov Institute of Developmental Biology, Russian Academy of Sciences, 26 Vavilova str., Moscow 119334, Russia
| | - Pavel A Erokhov
- N.K. Koltzov Institute of Developmental Biology, Russian Academy of Sciences, 26 Vavilova str., Moscow 119334, Russia
| | - Alexander D Finoshin
- N.K. Koltzov Institute of Developmental Biology, Russian Academy of Sciences, 26 Vavilova str., Moscow 119334, Russia
| | - Kim I Adameyko
- N.K. Koltzov Institute of Developmental Biology, Russian Academy of Sciences, 26 Vavilova str., Moscow 119334, Russia
| | - Maryia Yu Mishyna
- M.V. Lomonosov Moscow State University, Faculty of Biology, 1-12 Leninskie Gory, Moscow 119991, Russia
| | - Andrey V Moiseenko
- M.V. Lomonosov Moscow State University, Faculty of Biology, 1-12 Leninskie Gory, Moscow 119991, Russia
| | - Olga S Sokolova
- M.V. Lomonosov Moscow State University, Faculty of Biology, 1-12 Leninskie Gory, Moscow 119991, Russia
| | - Olga V Orlova
- V.A. Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 32 Vavilova str., Moscow 119334, Russia
| | - Svetlana N Beljelarskaya
- V.A. Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 32 Vavilova str., Moscow 119334, Russia
| | - Marina V Serebryakova
- A.N. Belozersky Institute of Physico-Chemical Biology MSU, 1c40 Leniniskie Gory, Moscow 119234, Russia
| | - Maria I Indeykina
- N.M. Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 4 Kosygina str., Moscow 119334, Russia
| | - Anna E Bugrova
- N.M. Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 4 Kosygina str., Moscow 119334, Russia
| | - Alexey S Kononikhin
- N.M. Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 4 Kosygina str., Moscow 119334, Russia; Skolkovo Institute of Science and Technology, 3 Ulitsa Nobelya, Moscow region, Skolkovo 121205, Russia
| | - Victor S Mikhailov
- N.K. Koltzov Institute of Developmental Biology, Russian Academy of Sciences, 26 Vavilova str., Moscow 119334, Russia.
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20
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Buneeva OA, Medvedev AE. [Ubiquitin-independent protein degradation in proteasomes]. BIOMEDIT︠S︡INSKAI︠A︡ KHIMII︠A︡ 2019; 64:134-148. [PMID: 29723144 DOI: 10.18097/pbmc20186402134] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Proteasomes are large supramolecular protein complexes present in all prokaryotic and eukaryotic cells, where they perform targeted degradation of intracellular proteins. Until recently, it was generally accepted that prior proteolytic degradation in proteasomes the proteins had to be targeted by ubiquitination: the ATP-dependent addition of (typically four sequential) residues of the low-molecular ubiquitin protein, involving the ubiquitin-activating enzyme, ubiquitin-conjugating enzyme and ubiquitin ligase. The cytoplasm and nucleoplasm proteins labeled in this way are then digested in 26S proteasomes. However, in recent years it has become increasingly clear that using this route the cell eliminates only a part of unwanted proteins. Many proteins can be cleaved by the 20S proteasome in an ATP-independent manner and without previous ubiquitination. Ubiquitin-independent protein degradation in proteasomes is a relatively new area of studies of the role of the ubiquitin-proteasome system. However, recent data obtained in this direction already correct existing concepts about proteasomal degradation of proteins and its regulation. Ubiquitin-independent proteasome degradation needs the main structural precondition in proteins: the presence of unstructured regions in the amino acid sequences that provide interaction with the proteasome. Taking into consideration that in humans almost half of all genes encode proteins that contain a certain proportion of intrinsically disordered regions, it appears that the list of proteins undergoing ubiquitin-independent degradation will demonstrate further increase. Since 26S of proteasomes account for only 30% of the total proteasome content in mammalian cells, most of the proteasomes exist in the form of 20S complexes. The latter suggests that ubiquitin-independent proteolysis performed by the 20S proteasome is a natural process of removing damaged proteins from the cell and maintaining a constant level of intrinsically disordered proteins. In this case, the functional overload of proteasomes in aging and/or other types of pathological processes, if it is not accompanied by triggering more radical mechanisms for the elimination of damaged proteins, organelles and whole cells, has the most serious consequences for the whole organism.
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Affiliation(s)
- O A Buneeva
- Institute of Biomedical Chemistry, Moscow, Russia
| | - A E Medvedev
- Institute of Biomedical Chemistry, Moscow, Russia
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21
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Kim HT, Collins GA, Goldberg AL. Measurement of the Multiple Activities of 26S Proteasomes. Methods Mol Biol 2019; 1844:289-308. [PMID: 30242717 DOI: 10.1007/978-1-4939-8706-1_19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Because proteasomes catalyze most of the protein degradation in mammalian cells, and their functioning is essential for cellular homeostasis, proteasome structure, biochemical mechanisms, and regulation in normal and disease states are now widely studied and are of major importance. In addition, inhibitors of the proteasome's peptidase activity have proven to be very valuable as research tools and in the treatment of hematologic malignancies, and a number of newer pharmacological agents that alter proteasome function are being developed. The rapid degradation of ubiquitinated proteins by the 26S proteasome involves multiple enzymatic and non-enzymatic steps, including the binding of ubiquitinated substrates to the 19S particle (Subheading 3.2), opening the gated substrate entry channel into the 20S particle (Subheading 3.3), disassembly of the Ub chain (Subheading 3.4), ATP hydrolysis (Subheading 3.5), substrate unfolding and translocation, and proteolysis within the 20S particle (Subheadings 3.3 and 3.7). Assaying each of these processes is important if we are to fully understand the physiological regulation of proteasome function and the effects of disease or drugs. Here, we describe several methods that we have found useful to measure many of these individual activities using purified proteasomes. Studies using these approaches have already provided valuable new insights into the effects of post-synthetic modifications to 26S subunits, the physiological regulation of the ubiquitin-proteasome system, and the impairment of proteasome activity in neurodegenerative disease. These advances would not have been possible if only the standard assays of peptidase activity were used.
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Affiliation(s)
- Hyoung Tae Kim
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | | | - Alfred L Goldberg
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA.
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Abstract
The ubiquitin proteasome system (UPS) degrades individual proteins in a highly regulated fashion and is responsible for the degradation of misfolded, damaged, or unneeded cellular proteins. During the past 20 years, investigators have established a critical role for the UPS in essentially every cellular process, including cell cycle progression, transcriptional regulation, genome integrity, apoptosis, immune responses, and neuronal plasticity. At the center of the UPS is the proteasome, a large and complex molecular machine containing a multicatalytic protease complex. When the efficiency of this proteostasis system is perturbed, misfolded and damaged protein aggregates can accumulate to toxic levels and cause neuronal dysfunction, which may underlie many neurodegenerative diseases. In addition, many cancers rely on robust proteasome activity for degrading tumor suppressors and cell cycle checkpoint inhibitors necessary for rapid cell division. Thus, proteasome inhibitors have proven clinically useful to treat some types of cancer, especially multiple myeloma. Numerous cellular processes rely on finely tuned proteasome function, making it a crucial target for future therapeutic intervention in many diseases, including neurodegenerative diseases, cystic fibrosis, atherosclerosis, autoimmune diseases, diabetes, and cancer. In this review, we discuss the structure and function of the proteasome, the mechanisms of action of different proteasome inhibitors, various techniques to evaluate proteasome function in vitro and in vivo, proteasome inhibitors in preclinical and clinical development, and the feasibility for pharmacological activation of the proteasome to potentially treat neurodegenerative disease.
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Affiliation(s)
- Tiffany A Thibaudeau
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, West Virginia
| | - David M Smith
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, West Virginia
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Morozov AV, Karpov VL. Biological consequences of structural and functional proteasome diversity. Heliyon 2018; 4:e00894. [PMID: 30417153 PMCID: PMC6218844 DOI: 10.1016/j.heliyon.2018.e00894] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/25/2018] [Accepted: 10/24/2018] [Indexed: 12/21/2022] Open
Abstract
Cell homeostasis and regulation of metabolic pathways are ensured by synthesis, proper folding and efficient degradation of a vast amount of proteins. Ubiquitin-proteasome system (UPS) degrades most intracellular proteins and thus, participates in regulation of cellular metabolism. Within the UPS, proteasomes are the elements that perform substrate cleavage. However, the proteasomes in the organism are diverse. Structurally different proteasomes are present not only in different types of cells, but also in a single cell. The reason for proteasome heterogeneity is not fully understood. This review briefly encompasses mammalian proteasome structure and function, and discusses biological relevance of proteasome diversity for a range of important cellular functions including internal and external signaling.
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Affiliation(s)
- Alexey V Morozov
- W.A. Engelhardt Institute of Molecular Biology, RAS, 119991, Moscow, Russia
| | - Vadim L Karpov
- W.A. Engelhardt Institute of Molecular Biology, RAS, 119991, Moscow, Russia
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24
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Buneeva OA, Medvedev AE. Ubiquitin-Independent Degradation of Proteins in Proteasomes. BIOCHEMISTRY (MOSCOW), SUPPLEMENT SERIES B: BIOMEDICAL CHEMISTRY 2018. [DOI: 10.1134/s1990750818030022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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25
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Gaczynska M, Osmulski PA. Targeting Protein-Protein Interactions in the Ubiquitin-Proteasome Pathway. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2017; 110:123-165. [PMID: 29412995 DOI: 10.1016/bs.apcsb.2017.09.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The ubiquitin-proteasome pathway (UPP) is a major venue for controlled intracellular protein degradation in Eukaryota. The machinery of several hundred proteins is involved in recognizing, tagging, transporting, and cleaving proteins, all in a highly regulated manner. Short-lived transcription factors, misfolded translation products, stress-damaged polypeptides, or worn-out long-lived proteins, all can be found among the substrates of UPP. Carefully choreographed protein-protein interactions (PPI) are involved in each step of the pathway. For many of the steps small-molecule inhibitors have been identified and often they directly or indirectly target PPI. The inhibitors may destabilize intracellular proteostasis and trigger apoptosis. So far this is the most explored option used as an anticancer strategy. Alternatively, substrate-specific polyubiquitination may be regulated for a precise intervention aimed at a particular metabolic pathway. This very attractive opportunity is moving close to clinical application. The best known drug target in UPP is the proteasome: the end point of the journey of a protein destined for degradation. The proteasome alone is a perfect object to study the mechanisms and roles of PPI on many levels. This giant protease is built from multisubunit modules and additionally utilizes a service from transient protein ligands, for example, delivering substrates. An elaborate set of PPI within the highest-order proteasome assembly is involved in substrate recognition and processing. Below we will outline PPI involved in the UPP and discuss the growing prospects for their utilization in pharmacological interventions.
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Affiliation(s)
- Maria Gaczynska
- Institute of Biotechnology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States.
| | - Pawel A Osmulski
- Institute of Biotechnology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
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Erokhov PA, Lyupina YV, Radchenko AS, Kolacheva AA, Nikishina YO, Sharova NP. Detection of active proteasome structures in brain extracts: proteasome features of August rat brain with violations in monoamine metabolism. Oncotarget 2017; 8:70941-70957. [PMID: 29050334 PMCID: PMC5642609 DOI: 10.18632/oncotarget.20208] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 07/23/2017] [Indexed: 12/15/2022] Open
Abstract
The aim of this work was to detect changes in proteasome pools of brain parts of August rats with monoamine metabolism violations in comparison with that of control Wistar rats. To reveal active proteasome structures, a method of native electrophoresis for the analysis of crude tissue fractions was developed. By means of this method and following Western blotting, the most pronounced changes in reorganization of proteasome structures were detected in proteasome pool of the brain cortex of August rats. Main findings are the enhanced expression of immune proteasome subtypes containing proteolytic subunit LMP2 and activator PA28αβ as well as immune proteasome subtypes containing proteolytic subunit LMP7 and activator PA700 and simultaneously decreased expression of subtypes with subunit LMP2 and activator PA700 in the brain cortex of August rats compared to that of Wistar rats. These results were indirectly confirmed by SDS PAGE method followed by Western blotting, which showed the increased quantities of immune subunits and proteasome activators in the brain cortex of August rats compared to that of Wistar rats. Immune proteasomes were revealed by immunohistochemistry in neurons, but not in glial cells of August and Wistar rat cortex. The detected reorganization of proteasome pools is likely to be important for production of special peptides to provide the steady interaction between neurons and adaptation of central nervous system to conditions caused by monoamine metabolism deviations.
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Affiliation(s)
- Pavel A. Erokhov
- Laboratory of Biochemistry of Ontogenesis Processes, N.K. Koltsov Institute of Developmental Biology of Russian Academy of Sciences, Moscow, Russia
| | - Yulia V. Lyupina
- Laboratory of Biochemistry of Ontogenesis Processes, N.K. Koltsov Institute of Developmental Biology of Russian Academy of Sciences, Moscow, Russia
| | - Alexandra S. Radchenko
- Laboratory of Biochemistry of Ontogenesis Processes, N.K. Koltsov Institute of Developmental Biology of Russian Academy of Sciences, Moscow, Russia
| | - Anna A. Kolacheva
- Laboratory of Neural and Neuroendocrine Regulations, N.K. Koltsov Institute of Developmental Biology of Russian Academy of Sciences, Moscow, Russia
| | - Yulia O. Nikishina
- Laboratory of Neural and Neuroendocrine Regulations, N.K. Koltsov Institute of Developmental Biology of Russian Academy of Sciences, Moscow, Russia
| | - Natalia P. Sharova
- Laboratory of Biochemistry of Ontogenesis Processes, N.K. Koltsov Institute of Developmental Biology of Russian Academy of Sciences, Moscow, Russia
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Witkowska J, Giżyńska M, Grudnik P, Golik P, Karpowicz P, Giełdoń A, Dubin G, Jankowska E. Crystal structure of a low molecular weight activator Blm-pep with yeast 20S proteasome - insights into the enzyme activation mechanism. Sci Rep 2017; 7:6177. [PMID: 28733623 PMCID: PMC5522460 DOI: 10.1038/s41598-017-05997-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 06/28/2017] [Indexed: 11/22/2022] Open
Abstract
Proteasomes are responsible for protein turnover in eukaryotic cells, degrading short-lived species but also removing improperly folded or oxidatively damaged ones. Dysfunction of a proteasome results in gradual accumulation of misfolded/damaged proteins, leading to their aggregation. It has been postulated that proteasome activators may facilitate removal of such aggregation-prone proteins and thus prevent development of neurodegenerative disorders. However, the discovery of pharmacologically relevant compounds is hindered by insufficient structural understanding of the activation process. In this study we provide a model peptidic activator of human proteasome and analyze the structure-activity relationship within this novel scaffold. The binding mode of the activator at the relevant pocket within the proteasome has been determined by X-ray crystallography. This crystal structure provides an important basis for rational design of pharmacological compounds. Moreover, by providing a novel insight into the proteasome gating mechanism, our results allow the commonly accepted model of proteasome regulation to be revisited.
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Affiliation(s)
- Julia Witkowska
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308, Gdańsk, Poland
| | - Małgorzata Giżyńska
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308, Gdańsk, Poland
| | - Przemysław Grudnik
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Krakow, Poland
- Malopolska Centre of Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Krakow, Poland
| | - Przemysław Golik
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Krakow, Poland
- Malopolska Centre of Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Krakow, Poland
| | - Przemysław Karpowicz
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308, Gdańsk, Poland
| | - Artur Giełdoń
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308, Gdańsk, Poland
| | - Grzegorz Dubin
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Krakow, Poland.
- Malopolska Centre of Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Krakow, Poland.
| | - Elżbieta Jankowska
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308, Gdańsk, Poland.
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The Logic of the 26S Proteasome. Cell 2017; 169:792-806. [PMID: 28525752 DOI: 10.1016/j.cell.2017.04.023] [Citation(s) in RCA: 588] [Impact Index Per Article: 84.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 04/13/2017] [Accepted: 04/14/2017] [Indexed: 12/14/2022]
Abstract
The ubiquitin proteasome pathway is responsible for most of the protein degradation in mammalian cells. Rates of degradation by this pathway have generally been assumed to be determined by rates of ubiquitylation. However, recent studies indicate that proteasome function is also tightly regulated and determines whether a ubiquitylated protein is destroyed or deubiquitylated and survives longer. This article reviews recent advances in our understanding of the proteasome's multistep ATP-dependent mechanism, its biochemical and structural features that ensure efficient proteolysis and ubiquitin recycling while preventing nonselective proteolysis, and the regulation of proteasome activity by interacting proteins and subunit modifications, especially phosphorylation.
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Bolten M, Delley CL, Leibundgut M, Boehringer D, Ban N, Weber-Ban E. Structural Analysis of the Bacterial Proteasome Activator Bpa in Complex with the 20S Proteasome. Structure 2016; 24:2138-2151. [PMID: 27839949 DOI: 10.1016/j.str.2016.10.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 10/04/2016] [Accepted: 10/12/2016] [Indexed: 11/19/2022]
Abstract
Mycobacterium tuberculosis harbors proteasomes that recruit substrates for degradation through an ubiquitin-like modification pathway. Recently, a non-ATPase activator termed Bpa (bacterial proteasome activator) was shown to support an alternate proteasomal degradation pathway. Here, we present the cryo-electron microscopy (cryo-EM) structure of Bpa in complex with the 20S core particle (CP). For docking into the cryo-EM density, we solved the X-ray structure of Bpa, showing that it forms tight four-helix bundles arranged into a 12-membered ring with a 40 Å wide central pore and the C-terminal helix of each protomer protruding from the ring. The Bpa model was fitted into the cryo-EM map of the Bpa-CP complex, revealing its architecture and striking symmetry mismatch. The Bpa-CP interface was resolved to 3.5 Å, showing the interactions between the C-terminal GQYL motif of Bpa and the proteasome α-rings. This docking mode is related to the one observed for eukaryotic activators with features specific to the bacterial complex.
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Affiliation(s)
- Marcel Bolten
- ETH Zurich, Institute of Molecular Biology & Biophysics, 8093 Zurich, Switzerland
| | - Cyrille L Delley
- ETH Zurich, Institute of Molecular Biology & Biophysics, 8093 Zurich, Switzerland
| | - Marc Leibundgut
- ETH Zurich, Institute of Molecular Biology & Biophysics, 8093 Zurich, Switzerland
| | - Daniel Boehringer
- ETH Zurich, Institute of Molecular Biology & Biophysics, 8093 Zurich, Switzerland
| | - Nenad Ban
- ETH Zurich, Institute of Molecular Biology & Biophysics, 8093 Zurich, Switzerland
| | - Eilika Weber-Ban
- ETH Zurich, Institute of Molecular Biology & Biophysics, 8093 Zurich, Switzerland.
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30
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Raynes R, Pomatto LCD, Davies KJA. Degradation of oxidized proteins by the proteasome: Distinguishing between the 20S, 26S, and immunoproteasome proteolytic pathways. Mol Aspects Med 2016; 50:41-55. [PMID: 27155164 DOI: 10.1016/j.mam.2016.05.001] [Citation(s) in RCA: 153] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 03/29/2016] [Accepted: 05/02/2016] [Indexed: 12/11/2022]
Abstract
The proteasome is a ubiquitous and highly plastic multi-subunit protease with multi-catalytic activity that is conserved in all eukaryotes. The most widely known function of the proteasome is protein degradation through the 26S ubiquitin-proteasome system, responsible for the vast majority of protein degradation during homeostasis. However, the proteasome also plays an important role in adaptive immune responses and adaptation to oxidative stress. The unbound 20S proteasome, the core common to all proteasome conformations, is the main protease responsible for degrading oxidized proteins. During periods of acute stress, the 19S regulatory cap of the 26S proteasome disassociates from the proteolytic core, allowing for immediate ATP/ubiquitin-independent protein degradation by the 20S proteasome. Despite the abundance of unbound 20S proteasome compared to other proteasomal conformations, many publications fail to distinguish between the two proteolytic systems and often regard the 26S proteasome as the dominant protease. Further confounding the issue are the differential roles these two proteolytic systems have in adaptation and aging. In this review, we will summarize the increasing evidence that the 20S core proteasome constitutes the major conformation of the proteasome system and that it is far from a latent protease requiring activation by binding regulators.
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Affiliation(s)
- Rachel Raynes
- Leonard Davis School of Gerontology of the Ethel Percy Andrus Gerontology Center, The University of Southern California, Los Angeles, CA 90089-0191, USA; Division of Molecular and Computational Biology, Department of Biological Sciences of the Dornsife College of Letters, Arts, and Sciences, The University of Southern California, Los Angeles, CA 90089-0191, USA
| | - Laura C D Pomatto
- Leonard Davis School of Gerontology of the Ethel Percy Andrus Gerontology Center, The University of Southern California, Los Angeles, CA 90089-0191, USA; Division of Molecular and Computational Biology, Department of Biological Sciences of the Dornsife College of Letters, Arts, and Sciences, The University of Southern California, Los Angeles, CA 90089-0191, USA
| | - Kelvin J A Davies
- Leonard Davis School of Gerontology of the Ethel Percy Andrus Gerontology Center, The University of Southern California, Los Angeles, CA 90089-0191, USA; Division of Molecular and Computational Biology, Department of Biological Sciences of the Dornsife College of Letters, Arts, and Sciences, The University of Southern California, Los Angeles, CA 90089-0191, USA.
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Welk V, Coux O, Kleene V, Abeza C, Trümbach D, Eickelberg O, Meiners S. Inhibition of Proteasome Activity Induces Formation of Alternative Proteasome Complexes. J Biol Chem 2016; 291:13147-59. [PMID: 27129254 DOI: 10.1074/jbc.m116.717652] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Indexed: 11/06/2022] Open
Abstract
The proteasome is an intracellular protease complex consisting of the 20S catalytic core and its associated regulators, including the 19S complex, PA28αβ, PA28γ, PA200, and PI31. Inhibition of the proteasome induces autoregulatory de novo formation of 20S and 26S proteasome complexes. Formation of alternative proteasome complexes, however, has not been investigated so far. We here show that catalytic proteasome inhibition results in fast recruitment of PA28γ and PA200 to 20S and 26S proteasomes within 2-6 h. Rapid formation of alternative proteasome complexes did not involve transcriptional activation of PA28γ and PA200 but rather recruitment of preexisting activators to 20S and 26S proteasome complexes. Recruitment of proteasomal activators depended on the extent of active site inhibition of the proteasome with inhibition of β5 active sites being sufficient for inducing recruitment. Moreover, specific inhibition of 26S proteasome activity via siRNA-mediated knockdown of the 19S subunit RPN6 induced recruitment of only PA200 to 20S proteasomes, whereas PA28γ was not mobilized. Here, formation of alternative PA200 complexes involved transcriptional activation of the activator. Alternative proteasome complexes persisted when cells had regained proteasome activity after pulse exposure to proteasome inhibitors. Knockdown of PA28γ sensitized cells to proteasome inhibitor-mediated growth arrest. Thus, formation of alternative proteasome complexes appears to be a formerly unrecognized but integral part of the cellular response to impaired proteasome function and altered proteostasis.
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Affiliation(s)
- Vanessa Welk
- From the Comprehensive Pneumology Center (CPC), University Hospital, Ludwig-Maximilians University, Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), 81377 Munich, Germany
| | - Olivier Coux
- the Centre de Recherche de Biochimie Macromoléculaire (CRBM-CNRS UMR 5237), Université de Montpellier, 34293 Montpellier, France, and
| | - Vera Kleene
- From the Comprehensive Pneumology Center (CPC), University Hospital, Ludwig-Maximilians University, Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), 81377 Munich, Germany
| | - Claire Abeza
- the Centre de Recherche de Biochimie Macromoléculaire (CRBM-CNRS UMR 5237), Université de Montpellier, 34293 Montpellier, France, and
| | - Dietrich Trümbach
- the Institute of Developmental Genetics, Helmholtz Zentrum München, 85764 Neuherberg, Germany
| | - Oliver Eickelberg
- From the Comprehensive Pneumology Center (CPC), University Hospital, Ludwig-Maximilians University, Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), 81377 Munich, Germany
| | - Silke Meiners
- From the Comprehensive Pneumology Center (CPC), University Hospital, Ludwig-Maximilians University, Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), 81377 Munich, Germany,
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32
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Abstract
All living organisms require protein degradation to terminate biological processes and remove damaged proteins. One such machine is the 20S proteasome, a specialized barrel-shaped and compartmentalized multicatalytic protease. The activity of the 20S proteasome generally requires the binding of regulators/proteasome activators (PAs), which control the entrance of substrates. These include the PA700 (19S complex), which assembles with the 20S and forms the 26S proteasome and allows the efficient degradation of proteins usually labeled by ubiquitin tags, PA200 and PA28, which are involved in proteolysis through ubiquitin-independent mechanisms and PI31, which was initially identified as a 20S inhibitor in vitro. Unlike 20S proteasome, shown to be present in all Eukaryotes and Archaea, the evolutionary history of PAs remained fragmentary. Here, we made a comprehensive survey and phylogenetic analyses of the four types of regulators in 17 clades covering most of the eukaryotic supergroups. We found remarkable conservation of each PA700 subunit in all eukaryotes, indicating that the current complex PA700 structure was already set up in the last eukaryotic common ancestor (LECA). Also present in LECA, PA200, PA28, and PI31 showed a more contrasted evolutionary picture, because many lineages have subsequently lost one or two of them. The paramount conservation of PA700 composition in all eukaryotes and the dynamic evolution of PA200, PA28, and PI31 are discussed in the light of current knowledge on their physiological roles.
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Affiliation(s)
- Philippe Fort
- CNRS, CRBM, UMR5237, Montpellier, France Université de Montpellier, France
| | - Andrey V Kajava
- CNRS, CRBM, UMR5237, Montpellier, France Université de Montpellier, France Institut de Biologie Computationnelle, Montpellier, France
| | - Fredéric Delsuc
- Université de Montpellier, France CNRS, IRD, Institut des Sciences de l'Evolution, UMR 5554, Montpellier, France
| | - Olivier Coux
- CNRS, CRBM, UMR5237, Montpellier, France Université de Montpellier, France
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33
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Abstract
Protein homeostasis relies on a balance between protein folding and protein degradation. Molecular chaperones like Hsp70 and Hsp90 fulfil well-defined roles in protein folding and conformational stability via ATP dependent reaction cycles. These folding cycles are controlled by associations with a cohort of non-client protein co-chaperones, such as Hop, p23 and Aha1. Pro-folding co-chaperones facilitate the transit of the client protein through the chaperone mediated folding process. However, chaperones are also involved in ubiquitin-mediated proteasomal degradation of client proteins. Similar to folding complexes, the ability of chaperones to mediate protein degradation is regulated by co-chaperones, such as the C terminal Hsp70 binding protein (CHIP). CHIP binds to Hsp70 and Hsp90 chaperones through its tetratricopeptide repeat (TPR) domain and functions as an E3 ubiquitin ligase using a modified RING finger domain (U-box). This unique combination of domains effectively allows CHIP to network chaperone complexes to the ubiquitin-proteasome system. This chapter reviews the current understanding of CHIP as a co-chaperone that switches Hsp70/Hsp90 chaperone complexes from protein folding to protein degradation.
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Affiliation(s)
- Adrienne L Edkins
- Department of Biochemistry and Microbiology, Biomedical Biotechnology Research Unit (BioBRU), Rhodes University, 6140, Grahamstown, South Africa,
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34
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Acquah JRQ, Haratake K, Rakwal R, Udono H, Chiba T. Hsp90 and ECM29 Are Important to Maintain the Integrity of Mammalian 26S Proteasome. ACTA ACUST UNITED AC 2015. [DOI: 10.4236/abc.2015.57022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Meiners S, Keller IE, Semren N, Caniard A. Regulation of the proteasome: evaluating the lung proteasome as a new therapeutic target. Antioxid Redox Signal 2014; 21:2364-82. [PMID: 24437504 DOI: 10.1089/ars.2013.5798] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
SIGNIFICANCE Lung diseases are on the second rank worldwide with respect to morbidity and mortality. For most respiratory diseases, no effective therapies exist. Whereas the proteasome has been successfully evaluated as a novel target for therapeutic interventions in cancer, neurodegenerative, and cardiac disorders, there is a profound lack of knowledge on the regulation of proteasome activity in chronic and acute lung diseases. RECENT ADVANCES There are various means of how the amount of active proteasome complexes in the cell can be regulated such as transcriptional regulation of proteasomal subunit expression, association with different regulators, assembly and half-life of proteasomes and regulatory complexes, as well as post-translational modifications. It also becomes increasingly evident that proteasome activity is fine-tuned and depends on the state of the cell. We propose here that 20S proteasomes and their regulators can be regarded as dynamic building blocks, which assemble or disassemble in response to cellular needs. The composition of proteasome complexes in a cell may vary depending on tissue, cell type and compartment, stage of development, or pathological context. CRITICAL ISSUES AND FUTURE DIRECTIONS Dissecting the expression and regulation of the various catalytic forms of 20S proteasomes, such as constitutive, immuno-, and mixed proteasomes, together with their associated regulatory complexes will not only greatly enhance our understanding of proteasome function in lung pathogenesis but will also pave the way to develop new classes of drugs that inhibit or activate proteasome function in a defined setting for treatment of lung diseases.
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Affiliation(s)
- Silke Meiners
- Comprehensive Pneumology Center (CPC), University Hospital , Ludwig-Maximilians University, Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Munich, Germany
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36
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Enenkel C. Nuclear transport of yeast proteasomes. Biomolecules 2014; 4:940-55. [PMID: 25333764 PMCID: PMC4279164 DOI: 10.3390/biom4040940] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 08/18/2014] [Accepted: 09/26/2014] [Indexed: 12/25/2022] Open
Abstract
Proteasomes are conserved protease complexes enriched in the nuclei of dividing yeast cells, a major site for protein degradation. If yeast cells do not proliferate and transit to quiescence, metabolic changes result in the dissociation of proteasomes into proteolytic core and regulatory complexes and their sequestration into motile cytosolic proteasome storage granuli. These granuli rapidly clear with the resumption of growth, releasing the stored proteasomes, which relocalize back to the nucleus to promote cell cycle progression. Here, I report on three models of how proteasomes are transported from the cytoplasm into the nucleus of yeast cells. The first model applies for dividing yeast and is based on the canonical pathway using classical nuclear localization sequences of proteasomal subcomplexes and the classical import receptor importin/karyopherin αβ. The second model applies for quiescent yeast cells, which resume growth and use Blm10, a HEAT-like repeat protein structurally related to karyopherin β, for nuclear import of proteasome core particles. In the third model, the fully-assembled proteasome is imported into the nucleus. Our still marginal knowledge about proteasome dynamics will inspire the discussion on how protein degradation by proteasomes may be regulated in different cellular compartments of dividing and quiescent eukaryotic cells.
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Affiliation(s)
- Cordula Enenkel
- Department of Biochemistry, University of Toronto, Medical Sciences Building, 1 King's College Circle, Toronto, ON M5S 1A8, Canada.
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37
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Ben-Nissan G, Sharon M. Regulating the 20S proteasome ubiquitin-independent degradation pathway. Biomolecules 2014; 4:862-84. [PMID: 25250704 PMCID: PMC4192676 DOI: 10.3390/biom4030862] [Citation(s) in RCA: 243] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Revised: 08/27/2014] [Accepted: 09/05/2014] [Indexed: 02/07/2023] Open
Abstract
For many years, the ubiquitin-26S proteasome degradation pathway was considered the primary route for proteasomal degradation. However, it is now becoming clear that proteins can also be targeted for degradation by the core 20S proteasome itself. Degradation by the 20S proteasome does not require ubiquitin tagging or the presence of the 19S regulatory particle; rather, it relies on the inherent structural disorder of the protein being degraded. Thus, proteins that contain unstructured regions due to oxidation, mutation, or aging, as well as naturally, intrinsically unfolded proteins, are susceptible to 20S degradation. Unlike the extensive knowledge acquired over the years concerning degradation by the 26S proteasome, relatively little is known about the means by which 20S-mediated proteolysis is controlled. Here, we describe our current understanding of the regulatory mechanisms that coordinate 20S proteasome-mediated degradation, and highlight the gaps in knowledge that remain to be bridged.
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Affiliation(s)
- Gili Ben-Nissan
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 7610001, Israel.
| | - Michal Sharon
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 7610001, Israel.
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38
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Qian MX, Pang Y, Liu CH, Haratake K, Du BY, Ji DY, Wang GF, Zhu QQ, Song W, Yu Y, Zhang XX, Huang HT, Miao S, Chen LB, Zhang ZH, Liang YN, Liu S, Cha H, Yang D, Zhai Y, Komatsu T, Tsuruta F, Li H, Cao C, Li W, Li GH, Cheng Y, Chiba T, Wang L, Goldberg AL, Shen Y, Qiu XB. Acetylation-mediated proteasomal degradation of core histones during DNA repair and spermatogenesis. Cell 2013; 153:1012-24. [PMID: 23706739 DOI: 10.1016/j.cell.2013.04.032] [Citation(s) in RCA: 227] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 03/11/2013] [Accepted: 04/08/2013] [Indexed: 01/12/2023]
Abstract
Histone acetylation plays critical roles in chromatin remodeling, DNA repair, and epigenetic regulation of gene expression, but the underlying mechanisms are unclear. Proteasomes usually catalyze ATP- and polyubiquitin-dependent proteolysis. Here, we show that the proteasomes containing the activator PA200 catalyze the polyubiquitin-independent degradation of histones. Most proteasomes in mammalian testes ("spermatoproteasomes") contain a spermatid/sperm-specific α subunit α4 s/PSMA8 and/or the catalytic β subunits of immunoproteasomes in addition to PA200. Deletion of PA200 in mice abolishes acetylation-dependent degradation of somatic core histones during DNA double-strand breaks and delays core histone disappearance in elongated spermatids. Purified PA200 greatly promotes ATP-independent proteasomal degradation of the acetylated core histones, but not polyubiquitinated proteins. Furthermore, acetylation on histones is required for their binding to the bromodomain-like regions in PA200 and its yeast ortholog, Blm10. Thus, PA200/Blm10 specifically targets the core histones for acetylation-mediated degradation by proteasomes, providing mechanisms by which acetylation regulates histone degradation, DNA repair, and spermatogenesis.
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Affiliation(s)
- Min-Xian Qian
- Key Laboratory of Cell Proliferation and Regulation Biology, Ministry of Education, and College of Life Sciences, Beijing Normal University, 19 Xinjiekouwai Avenue, Beijing 100875, China
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39
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Abstract
Rapamycin is a canonical allosteric inhibitor of the mammalian tarpet of rapamycin (mTOR) kinase with immunosuppressive and proapoptotic activities. We found that in vitro rapamycin also regulates the proteasome, which is an essential intracellular protease of the ubiquitin-proteasome pathway. Rapamycin inhibits proteinase and selected peptidase activities of the catalytic core proteasome at low micromolar concentrations. Moreover, the drug interferes with binding of the 19S cap essential for processing of polyubiquitinylated substrates and with the PA200 proteasome activator to the 20S catalytic core proteasome. These protein complexes are known to bind to specific grooves on the α face region of the 20S core. Treatment with rapamycin affects the conformational dynamics of the proteasomal gate, which is centrally positioned within the α face and allosterically regulated element responsible for the intake of substrates. We showed that rapamycin shares all the proteasome targeting properties not only with other two-domain, closed-ring analogs (rapalogs) but also with its single domain mimics and seco-rapamycin, which is the first in vivo open-ring metabolite of rapamycin that does not affect mTOR. We hypothesize that rapamycin and related compounds bind to the α face and allosterically impact proteasome function. This article discusses the implications of our findings for the mechanism of in vivo actions of rapamycin and for the design of novel allosteric drugs targeting the proteasome.
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Affiliation(s)
- Pawel A Osmulski
- University of Texas Health Science Center at San Antonio, Department of Molecular Medicine, Institute of Biotechnology, 15355 Lambda Drive, San Antonio, TX 78245, USA
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40
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Lander GC, Martin A, Nogales E. The proteasome under the microscope: the regulatory particle in focus. Curr Opin Struct Biol 2013; 23:243-51. [PMID: 23498601 DOI: 10.1016/j.sbi.2013.02.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 02/13/2013] [Accepted: 02/13/2013] [Indexed: 10/27/2022]
Abstract
Since first imaged by electron microscopy, much effort has been placed into determining the structure and mechanism of the 26S proteasome. While the proteolytic core is understood in atomic detail, how substrates are engaged and transported to this core remains elusive. Substrate delivery is accomplished by a 19-subunit regulatory particle that binds to ubiquitinated substrates, detaches ubiquitin tags, unfolds the substrate, and translocates it into the peptidase in an ATP-dependent fashion. Recently, several labs have determined subnanometer cryoEM structures of the 26S proteasome, shedding light on the architecture of the regulatory complex. We discuss the biological insights into substrate processing provided by these structures, and the technical hurdles ahead to achieve an atomic resolution structure of the 26 proteasome.
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Affiliation(s)
- Gabriel C Lander
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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41
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Doherty KM, Pride LD, Lukose J, Snydsman BE, Charles R, Pramanik A, Muller EG, Botstein D, Moore CW. Loss of a 20S proteasome activator in Saccharomyces cerevisiae downregulates genes important for genomic integrity, increases DNA damage, and selectively sensitizes cells to agents with diverse mechanisms of action. G3 (BETHESDA, MD.) 2012; 2:943-59. [PMID: 22908043 PMCID: PMC3411250 DOI: 10.1534/g3.112.003376] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Accepted: 06/18/2012] [Indexed: 01/23/2023]
Abstract
Cytoprotective functions of a 20S proteasome activator were investigated. Saccharomyces cerevisiae Blm10 and human 20S proteasome activator 200 (PA200) are homologs. Comparative genome-wide analyses of untreated diploid cells lacking Blm10 and growing at steady state at defined growth rates revealed downregulation of numerous genes required for accurate chromosome structure, assembly and repair, and upregulation of a specific subset of genes encoding protein-folding chaperones. Blm10 loss or truncation of the Ubp3/Blm3 deubiquitinating enzyme caused massive chromosomal damage and cell death in homozygous diploids after phleomycin treatments, indicating that Blm10 and Ubp3/Blm3 function to stabilize the genome and protect against cell death. Diploids lacking Blm10 also were sensitized to doxorubicin, hydroxyurea, 5-fluorouracil, rapamycin, hydrogen peroxide, methyl methanesulfonate, and calcofluor. Fluorescently tagged Blm10 localized in nuclei, with enhanced fluorescence after DNA replication. After DNA damage that caused a classic G2/M arrest, fluorescence remained diffuse, with evidence of nuclear fragmentation in some cells. Protective functions of Blm10 did not require the carboxyl-terminal region that makes close contact with 20S proteasomes, indicating that protection does not require this contact or the truncated Blm10 can interact with the proteasome apart from this region. Without its carboxyl-terminus, Blm10((-339aa)) localized to nuclei in untreated, nonproliferating (G(0)) cells, but not during G(1) S, G(2), and M. The results indicate Blm10 functions in protective mechanisms that include the machinery that assures proper assembly of chromosomes. These essential guardian functions have implications for ubiquitin-independent targeting in anticancer therapy. Targeting Blm10/PA200 together with one or more of the upregulated chaperones or a conventional treatment could be efficacious.
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Affiliation(s)
- Kevin M. Doherty
- Department of Microbiology and Immunology, City University of New York Sophie Davis School of Biomedical Education, City College, New York, New York 10031-9101
- The Graduate Center Program in Biochemistry, City University of New York, New York, New York 10016-4309
| | - Leah D. Pride
- Department of Microbiology and Immunology, City University of New York Sophie Davis School of Biomedical Education, City College, New York, New York 10031-9101
- Department of Biochemistry, City College, City University of New York, New York, New York 10031-9101
| | - James Lukose
- Department of Microbiology and Immunology, City University of New York Sophie Davis School of Biomedical Education, City College, New York, New York 10031-9101
| | - Brian E. Snydsman
- Department of Biochemistry, University of Washington, Seattle, Washington 98195-7350
| | - Ronald Charles
- Department of Microbiology and Immunology, City University of New York Sophie Davis School of Biomedical Education, City College, New York, New York 10031-9101
| | - Ajay Pramanik
- Department of Microbiology and Immunology, City University of New York Sophie Davis School of Biomedical Education, City College, New York, New York 10031-9101
| | - Eric G. Muller
- Department of Biochemistry, University of Washington, Seattle, Washington 98195-7350
| | - David Botstein
- Lewis-Sigler Institute for Integrative Genomics and Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544-1004, and
| | - Carol Wood Moore
- Department of Microbiology and Immunology, City University of New York Sophie Davis School of Biomedical Education, City College, New York, New York 10031-9101
- Graduate Center Programs in Biochemistry and Biology, City University of New York, New York, New York 10016-4309
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Abstract
The ubiquitin-proteasomal system is an essential element of the protein quality control machinery in cells. The central part of this system is the 20S proteasome. The proteasome is a barrel-shaped multienzyme complex, containing several active centers hidden at the inner surface of the hollow cylinder. So, the regulation of the substrate entry toward the inner proteasomal surface is a key control mechanism of the activity of this protease. This chapter outlines the knowledge on the structure of the subunits of the 20S proteasome, the binding and structure of some proteasomal regulators and inducible proteasomal subunits. Therefore, this chapter imparts the knowledge on proteasomal structure which is required for the understanding of the following chapters.
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Dange T, Smith D, Noy T, Rommel PC, Jurzitza L, Cordero RJB, Legendre A, Finley D, Goldberg AL, Schmidt M. Blm10 protein promotes proteasomal substrate turnover by an active gating mechanism. J Biol Chem 2011; 286:42830-9. [PMID: 22025621 DOI: 10.1074/jbc.m111.300178] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
For optimal proteolytic function, the central core of the proteasome (core particle (CP) or 20S) has to associate with activators. We investigated the impact of the yeast activator Blm10 on proteasomal peptide and protein degradation. We found enhanced degradation of peptide substrates in the presence of Blm10 and demonstrated that Blm10 has the capacity to accelerate proteasomal turnover of the unstructured protein tau-441 in vitro. Mechanistically, proteasome activation requires the opening of a closed gate, which allows passage of unfolded proteins into the catalytic chamber. Our data indicate that gate opening by Blm10 is achieved via engagement of its C-terminal segment with the CP. Crucial for this activity is a conserved C-terminal YYX motif, with the penultimate tyrosine playing a preeminent role. Thus, Blm10 utilizes a gate opening strategy analogous to the proteasomal ATPases HbYX-dependent mechanism. Because gating incompetent Blm10 C-terminal point mutants confers a loss of function phenotype, we propose that the cellular function of Blm10 is based on CP association and activation to promote the degradation of proteasome substrates.
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Affiliation(s)
- Thomas Dange
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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Lee SYC, De la Mota-Peynado A, Roelofs J. Loss of Rpt5 protein interactions with the core particle and Nas2 protein causes the formation of faulty proteasomes that are inhibited by Ecm29 protein. J Biol Chem 2011; 286:36641-51. [PMID: 21878651 DOI: 10.1074/jbc.m111.280875] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The proteasome is a large and complex protease formed by 66 polypeptides. The assembly of the proteasome is assisted by at least nine chaperones. One of these chaperones, Nas2/p27, binds to the C-terminal region of the AAA-ATPase Rpt5. We report here that the tail of Rpt5 provides two functions. First, it facilitates the previously reported interaction with the proteasome core particle (CP). Second, it is essential for the interaction with Nas2. Deletion of the C-terminal amino acid of Rpt5 disrupts the CP interaction, but not the binding to Nas2. The latter is surprising considering Nas2 contains a PDZ domain, which is often involved in binding to C termini. Interestingly, deletion of the last three amino acids interferes with both functions. The disruption of the Rpt5-CP interactions gave distinct phenotypes different from disruption of the Nas2-Rpt5 interaction. Additionally, proteasomes purified from a Saccharomyces cerevisiae rpt5-Δ3 strain show a strong enrichment of Ecm29. The function of Ecm29, a proteasome-associated protein, is not well understood. Our data show that Ecm29 can inhibit proteasomes, because our Ecm29-containing proteasomes have reduced suc-LLVY-AMC hydrolytic activity. Consistent with this apparent role as negative regulator, the deletion of ECM29 rescues the phenotypes of rpt5-Δ3 and nas2Δ in an hsm3Δ background. In sum, the interactions facilitated by the tail of Rpt5 act synergistically to minimize the formation of faulty proteasomes, thereby preventing recognition and inhibition by Ecm29.
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Affiliation(s)
- Stella Yu-Chien Lee
- Molecular, Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, Kansas 66506, USA
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45
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Abstract
The ubiquitin/proteasome pathway is the major proteolytic quality control system in cells. In this review we discuss the impact of a deregulation of this pathway on neuronal function and its causal relationship to the intracellular deposition of ubiquitin protein conjugates in pathological inclusion bodies in all the major chronic neurodegenerative disorders, such as Alzheimer's, Parkinson's and Huntington's diseases as well as amyotrophic lateral sclerosis. We describe the intricate nature of the ubiquitin/proteasome pathway and discuss the paradox of protein aggregation, i.e. its potential toxic/protective effect in neurodegeneration. The relations between some of the dysfunctional components of the pathway and neurodegeneration are presented. We highlight possible ubiquitin/proteasome pathway-targeting therapeutic approaches, such as activating the proteasome, enhancing ubiquitination and promoting SUMOylation that might be important to slow/treat the progression of neurodegeneration. Finally, a model time line is presented for neurodegeneration starting at the initial injurious events up to protein aggregation and cell death, with potential time points for therapeutic intervention.
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Savulescu AF, Glickman MH. Proteasome activator 200: the heat is on... Mol Cell Proteomics 2011; 10:R110.006890. [PMID: 21389348 DOI: 10.1074/mcp.r110.006890] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Proteasomes play a key regulatory role in all eukaryotic cells by removing proteins in a timely manner. There are two predominant forms: The 20S core particle (CP) can hydrolyze peptides and certain unstructured proteins, and the 26S holoenzyme is able to proteolyse most proteins conjugated to ubiquitin. The 26S complex consists of a CP barrel with a 19S regulatory particle (RP; a.k.a PA700) attached to its outer surface. Several studies purified another proteasome activator with a MW of 200 kDa (PA200) that attaches to the same outer ring of the CP. A role for PA200 has been demonstrated in spermatogenesis, in response to DNA repair and in maintenance of mitochondrial inheritance. Enhanced levels of PA200-CP complexes are observed under conditions in which either activated or disrupted CP prevail, suggesting it participates in regulating overall proteolytic activity. PA200, or its yeast ortholog Blm10, may also incorporate into 26S proteasomes yielding PA200-CP-RP hybrids. A three-dimensional molecular structure determined by x-ray crystallography of Blm10-CP provides a model for activation. The carboxy terminus of Blm10 inserts into a dedicated pocket in the outer ring of the CP surface, whereas multiple HEAT-like repeats fold into an asymmetric solenoid wrapping around the central pore to stabilize a partially open conformation. The resulting hollow domelike structure caps the entire CP surface. This asymmetric structure may provide insight as to how the 19S RP, with two HEAT repeatlike subunits (Rpn1, Rpn2) alongside six ATPases (Rpt1-6), attaches to the same surface of the CP ring, and likewise, induces pore opening.
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Stadtmueller BM, Hill CP. Proteasome activators. Mol Cell 2011; 41:8-19. [PMID: 21211719 DOI: 10.1016/j.molcel.2010.12.020] [Citation(s) in RCA: 166] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Revised: 12/15/2010] [Accepted: 12/15/2010] [Indexed: 01/25/2023]
Abstract
Proteasomes degrade a multitude of protein substrates in the cytosol and nucleus, and thereby are essential for many aspects of cellular function. Because the proteolytic sites are sequestered in a closed barrel-shaped structure, activators are required to facilitate substrate access. Structural and biochemical studies of two activator families, 11S and Blm10, have provided insights to proteasome activation mechanisms, although the biological functions of these factors remain obscure. Recent advances have improved our understanding of the third activator family, including the 19S activator, which targets polyubiquitylated proteins for degradation. Here we present a structural perspective on how proteasomes are activated and how substrates are delivered to the proteolytic sites.
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Affiliation(s)
- Beth M Stadtmueller
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112-5650, USA
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Lopez AD, Tar K, Krügel U, Dange T, Ros IG, Schmidt M. Proteasomal degradation of Sfp1 contributes to the repression of ribosome biogenesis during starvation and is mediated by the proteasome activator Blm10. Mol Biol Cell 2011; 22:528-40. [PMID: 21209318 PMCID: PMC3046052 DOI: 10.1091/mbc.e10-04-0352] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The ribosome transcription activator Sfp1 is degraded by Blm10-proteasomes. Loss of BLM10 results in increased Sfp1 protein levels, increased transcription of ribosomal genes, and increased ribosome levels upon nutrient depletion. Thus Blm10-proteasome-mediated turnover of Sfp1 is a regulatory mechanism for ribosome biosynthesis repression. The regulation of ribosomal protein (RP) gene transcription is tightly linked to the nutrient status of the cell and is under the control of metabolic signaling pathways. In Saccharomyces cerevisiae several transcriptional activators mediate efficient RP gene transcription during logarithmic growth and dissociate from RP gene promoters upon nutrient limitation. Repression of RP gene transcription appears to be regulated predominantly by posttranslational modification and cellular localization of transcriptional activators. We report here that one of these factors, Sfp1, is degraded by the proteasome and that the proteasome activator Blm10 is required for regulated Sfp1 degradation. Loss of Blm10 results in the stabilization and increased nuclear abundance of Sfp1 during nutrient limitation, increased transcription of RP genes, increased levels of RPs, and decreased rapamycin-induced repression of RP genes. Thus we conclude that proteasomal degradation of Sfp1 is mediated by Blm10 and contributes to the repression of ribosome biogenesis under nutrient depletion.
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Affiliation(s)
- Antonio Diaz Lopez
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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49
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Abstract
The proteasome is the essential prime protease in all eukaryotes. The large, multisubunit, modular, and multifunctional enzyme is responsible for the majority of regulated intracellular protein degradation. It constitutes a part of the multienzyme ubiquitin-proteasome pathway, which is broadly implicated in recognition, tagging, and cleavage of proteins. The name "proteasome" refers to several types of protein assemblies sharing a common catalytic core particle. Additional protein modules attach to the core, regulate its activities, and broaden its functional capabilities. The structure of proteasomes has been studied extensively with multiple methods. The crystal structure of the core particle was solved for several species. However, only a single structure of the core particle decorated with PA26 activator has been determined. NMR spectroscopy was successfully applied to probe a much -simpler, archaebacterial type of the core particle. In turn, electron microscopy was very effective in exploring the spatial arrangement of many classes of assemblies. Still, the makeup of higher-order -complexes is not well established. Besides, the crystal structure provided very limited information on proteasome molecular dynamics. Atomic force microscopy (AFM) is an ideal technique to address questions that are unanswered by other approaches. For example, AFM is perfectly suited to study allosteric regulation of proteasome, the role of protein dynamics in enzymatic catalysis, and the spatial organization of modules and subunits in assemblies. Here, we present a method that probes the conformational diversity and dynamics of yeast core particle using the oscillating mode AFM in liquid. We are taking advantage of the observation that the tube-shaped core particle is equipped with a swinging gate leading to the catalytic chamber. We demonstrate how to identify distinct gate conformations in AFM images and how to characterize the gate dynamics controlled with ligands and disturbed by mutations.
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Affiliation(s)
- Maria Gaczynska
- Department of Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
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50
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Effantin G, Ishikawa T, De Donatis GM, Maurizi MR, Steven AC. Local and global mobility in the ClpA AAA+ chaperone detected by cryo-electron microscopy: functional connotations. Structure 2010; 18:553-62. [PMID: 20462489 DOI: 10.1016/j.str.2010.02.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Revised: 02/16/2010] [Accepted: 02/17/2010] [Indexed: 10/19/2022]
Abstract
The ClpA chaperone combines with the ClpP peptidase to perform targeted proteolysis in the bacterial cytoplasm. ClpA monomer has an N-terminal substrate-binding domain and two AAA+ ATPase domains (D1 and D2). ClpA hexamers stack axially on ClpP heptamers to form the symmetry-mismatched protease. We used cryo-electron microscopy to visualize the ClpA-ATPgammaS hexamer, in the context of ClpAP complexes. Two segments lining the axial channel show anomalously low density, indicating that these motifs, which have been implicated in substrate translocation, are mobile. We infer that ATP hydrolysis is accompanied by substantial structural changes in the D2 but not the D1 tier. The entire N domain is rendered invisible by large-scale fluctuations. When deletions of 10 and 15 residues were introduced into the linker, N domain mobility was reduced but not eliminated and changes were observed in enzymatic activities. Based on these observations, we present a pseudo-atomic model of ClpAP holoenzyme, a dynamic proteolytic nanomachine.
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Affiliation(s)
- Grégory Effantin
- Laboratory of Structural Biology Research, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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