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Arie M, Matzov D, Karmona R, Szenkier N, Stanhill A, Navon A. A non-symmetrical p97 conformation initiates a multistep recruitment of Ufd1/Npl4. iScience 2024; 27:110061. [PMID: 38947518 PMCID: PMC11214410 DOI: 10.1016/j.isci.2024.110061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Revised: 04/10/2024] [Accepted: 05/17/2024] [Indexed: 07/02/2024] Open
Abstract
In vitro experiments and cryo-EM structures of p97 and its cofactor, Ufd1/Npl4 (UN), elucidated substrate processing. Yet, the structural transitions and the related ATPase cycle upon UN binding remain unresolved. We captured two discrete conformations: One in which D1 protomers are ATP bound, while the D2 subunits are in the ADP state, presumably required for substrate engagement with the D2 pore; and a heterologous nucleotide state within the D1 ring in which only two NTDs are in the "up" ATP state that favors UN binding. Further analysis suggests that initially, UN binds p97's non-symmetrical conformation, this association promotes a structural transition upon which five NTDs shift to an "up" state and are poised to bind ATP. The UBXL domain of Npl4 was captured bound to an NTD in the ADP state, demonstrating a conformation that may provide directionality to incoming substrate and introduce the flexibility needed for substrate processing.
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Affiliation(s)
- Michal Arie
- Department of Immunology and Regenerative Biology, The Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Donna Matzov
- Department of Chemical and Structural Biology, The Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Rotem Karmona
- Department of Immunology and Regenerative Biology, The Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Natalia Szenkier
- Department of Immunology and Regenerative Biology, The Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Ariel Stanhill
- Department of Natural Sciences, The Open University of Israel, Raanana 4353701, Israel
| | - Ami Navon
- Department of Immunology and Regenerative Biology, The Weizmann Institute of Science, Rehovot 7610001, Israel
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2
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Conserved L464 in p97 D1-D2 linker is critical for p97 cofactor regulated ATPase activity. Biochem J 2021; 478:3185-3204. [PMID: 34405853 DOI: 10.1042/bcj20210288] [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: 04/27/2021] [Revised: 08/10/2021] [Accepted: 08/18/2021] [Indexed: 11/17/2022]
Abstract
p97 protein is a highly conserved, abundant, functionally diverse, structurally dynamic homohexameric AAA enzyme-containing N, D1, and D2 domains. A truncated p97 protein containing the N and D1 domains and the D1-D2 linker (ND1L) exhibits 79% of wild-type (WT) ATPase activity whereas the ND1 domain alone without the linker only has 2% of WT activity. To investigate the relationship between the D1-D2 linker and the D1 domain, we produced p97 ND1L mutants and demonstrated that this 22-residue linker region is essential for D1 ATPase activity. The conserved amino acid leucine 464 (L464) is critical for regulating D1 and D2 ATPase activity by p97 cofactors p37, p47, and Npl4-Ufd1 (NU). Changing leucine to alanine, proline, or glutamate increased the maximum rate of ATP turnover (kcat) of p47-regulated ATPase activities for these mutants, but not for WT. p37 and p47 increased the kcat of the proline substituted linker, suggesting that they induced linker conformations facilitating ATP hydrolysis. NU inhibited D1 ATPase activities of WT and mutant ND1L proteins, but activated D2 ATPase activity of full-length p97. To further understand the mutant mechanism, we used single-particle cryo-EM to visualize the full-length p97L464P and revealed the conformational change of the D1-D2 linker, resulting in a movement of the helix-turn-helix motif (543-569). Taken together with the biochemical and structural results we conclude that the linker helps maintain D1 in a competent conformation and relays the communication to/from the N-domain to the D1 and D2 ATPase domains, which are ∼50 Å away.
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3
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Ninagawa S, George G, Mori K. Mechanisms of productive folding and endoplasmic reticulum-associated degradation of glycoproteins and non-glycoproteins. Biochim Biophys Acta Gen Subj 2020; 1865:129812. [PMID: 33316349 DOI: 10.1016/j.bbagen.2020.129812] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Revised: 12/09/2020] [Accepted: 12/09/2020] [Indexed: 12/22/2022]
Abstract
BACKGROUND The quality of proteins destined for the secretory pathway is ensured by two distinct mechanisms in the endoplasmic reticulum (ER): productive folding of newly synthesized proteins, which is assisted by ER-localized molecular chaperones and in most cases also by disulfide bond formation and transfer of an oligosaccharide unit; and ER-associated degradation (ERAD), in which proteins unfolded or misfolded in the ER are recognized and processed for delivery to the ER membrane complex, retrotranslocated through the complex with simultaneous ubiquitination, extracted by AAA-ATPase to the cytosol, and finally degraded by the proteasome. SCOPE OF REVIEW We describe the mechanisms of productive folding and ERAD, with particular attention to glycoproteins versus non-glycoproteins, and to yeast versus mammalian systems. MAJOR CONCLUSION Molecular mechanisms of the productive folding of glycoproteins and non-glycoproteins mediated by molecular chaperones and protein disulfide isomerases are well conserved from yeast to mammals. Additionally, mammals have gained an oligosaccharide structure-dependent folding cycle for glycoproteins. The molecular mechanisms of ERAD are also well conserved from yeast to mammals, but redundant expression of yeast orthologues in mammals has been encountered, particularly for components involved in recognition and processing of glycoproteins and components of the ER membrane complex involved in retrotranslocation and simultaneous ubiquitination of glycoproteins and non-glycoproteins. This may reflect an evolutionary consequence of increasing quantity or quality needs toward mammals. GENERAL SIGNIFICANCE The introduction of innovative genome editing technology into analysis of the mechanisms of mammalian ERAD, as exemplified here, will provide new insights into the pathogenesis of various diseases.
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Affiliation(s)
- Satoshi Ninagawa
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
| | - Ginto George
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Kazutoshi Mori
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
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4
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Liu Y, Tan Z, Yang Y. Negative feedback and modern anti-cancer strategies targeting the ER stress response. FEBS Lett 2020; 594:4247-4265. [PMID: 33206409 DOI: 10.1002/1873-3468.14000] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 09/18/2020] [Accepted: 10/25/2020] [Indexed: 12/13/2022]
Abstract
Endoplasmic reticulum (ER) stress is a cell state in which misfolded or unfolded proteins are aberrantly accumulated in the ER. ER stress induces an evolutionarily conserved adaptive response, named the ER stress response, that deploys a self-regulated machinery to maintain cellular proteostasis. However, compared to its well-established canonical activation mechanism, the negative feedback mechanisms regulating the ER stress response remain unclear and no accepted methods or markers have been established. Several studies have documented that both endogenous and exogenous insults can induce ER stress in cancer. Based on this evidence, small molecule inhibitors targeting ER stress response have been designed to kill cancer cells, with some of them showing excellent curative effects. Here, we review recent advances in our understanding of negative feedback of the ER stress response and compare the markers used to date. We also summarize therapeutic inhibitors targeting ER stress response and highlight the promises and challenges ahead.
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Affiliation(s)
- Yaofu Liu
- Suzhou Institute of Systems Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, Suzhou, China
| | - Zhenzhi Tan
- Suzhou Institute of Systems Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, Suzhou, China
| | - Yili Yang
- Suzhou Institute of Systems Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, Suzhou, China
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5
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Patel C, Saad H, Shenkman M, Lederkremer GZ. Oxidoreductases in Glycoprotein Glycosylation, Folding, and ERAD. Cells 2020; 9:cells9092138. [PMID: 32971745 PMCID: PMC7563561 DOI: 10.3390/cells9092138] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 09/17/2020] [Accepted: 09/18/2020] [Indexed: 12/17/2022] Open
Abstract
N-linked glycosylation and sugar chain processing, as well as disulfide bond formation, are among the most common post-translational protein modifications taking place in the endoplasmic reticulum (ER). They are essential modifications that are required for membrane and secretory proteins to achieve their correct folding and native structure. Several oxidoreductases responsible for disulfide bond formation, isomerization, and reduction have been shown to form stable, functional complexes with enzymes and chaperones that are involved in the initial addition of an N-glycan and in folding and quality control of the glycoproteins. Some of these oxidoreductases are selenoproteins. Recent studies also implicate glycan machinery–oxidoreductase complexes in the recognition and processing of misfolded glycoproteins and their reduction and targeting to ER-associated degradation. This review focuses on the intriguing cooperation between the glycoprotein-specific cell machineries and ER oxidoreductases, and highlights open questions regarding the functions of many members of this large family.
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Affiliation(s)
- Chaitanya Patel
- The Shmunis School of Biomedicine and Cancer Research, Cell Biology Division, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel; (C.P.); (H.S.); (M.S.)
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Haddas Saad
- The Shmunis School of Biomedicine and Cancer Research, Cell Biology Division, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel; (C.P.); (H.S.); (M.S.)
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Marina Shenkman
- The Shmunis School of Biomedicine and Cancer Research, Cell Biology Division, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel; (C.P.); (H.S.); (M.S.)
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Gerardo Z. Lederkremer
- The Shmunis School of Biomedicine and Cancer Research, Cell Biology Division, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel; (C.P.); (H.S.); (M.S.)
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
- Correspondence:
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Abstract
The nucleus is enclosed by a double-membrane structure, the nuclear envelope, which separates the nucleoplasm from the cytoplasm. The outer nuclear membrane is continuous with the endoplasmic reticulum (ER), whereas the inner nuclear membrane (INM) is a specialized compartment with a unique proteome. In order to ensure compartmental homeostasis, INM-associated degradation (INMAD) is required for both protein quality control and regulated proteolysis of INM proteins. INMAD shares similarities with ER-associated degradation (ERAD). The mechanism of ERAD is well characterized, whereas the INMAD pathway requires further definition. Here we review the three different branches of INMAD, mediated by their respective E3 ubiquitin ligases: Doa10, Asi1-3, and APC/C. We clarify the distinction between ERAD and INMAD, their substrate recognition signals, and the subsequent processing by their respective degradation machineries. We also discuss the significance of cell-cycle and developmental regulation of protein clearance at the INM, and its relationship to human disease.
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Affiliation(s)
- Bailey Koch
- a Department of Biological Science, The Florida State University , Tallahassee , FL , USA
| | - Hong-Guo Yu
- a Department of Biological Science, The Florida State University , Tallahassee , FL , USA
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7
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Sui X, Pan M, Li YM. Insights into the Design of p97-targeting Small Molecules from Structural Studies on p97 Functional Mechanism. Curr Med Chem 2020; 27:298-316. [PMID: 31584361 DOI: 10.2174/0929867326666191004162411] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 08/24/2019] [Accepted: 08/27/2019] [Indexed: 12/14/2022]
Abstract
p97, also known as valosin-containing protein or CDC48, is a member of the AAA+ protein family that is highly conserved in eukaryotes. It binds to various cofactors in the body to perform its protein-unfolding function and participates in DNA repair, degradation of subcellular membrane proteins, and protein quality control pathways, among other processes. Its malfunction can lead to many diseases, such as inclusion body myopathy, associated with Paget's disease of bone and/or frontotemporal dementia, amyotrophic lateral sclerosis disease, and others. In recent years, many small-molecule inhibitors have been deployed against p97, including bis (diethyldithiocarbamate)- copper and CB-5083, which entered the first phase of clinical tests but failed. One bottleneck in the design of p97 drugs is that its molecular mechanism remains unclear. This paper summarizes recent studies on the molecular mechanisms of p97, which may lead to insight into how the next generation of small molecules targeting p97 can be designed.
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Affiliation(s)
- Xin Sui
- Department of Chemistry, Tsinghua University, Beijing 100086, China
| | - Man Pan
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois 60637, United States
| | - Yi-Ming Li
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, Anhui 230009, China
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8
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Abstract
p97 belongs to the functional diverse superfamily of AAA+ (ATPases Associated with diverse cellular Activities) ATPases and is characterized by an N-terminal regulatory domain and two stacked hexameric ATPase domains forming a central protein conducting channel. p97 is highly versatile and has key functions in maintaining protein homeostasis including protein quality control mechanisms like the ubiquitin proteasome system (UPS) and autophagy to disassemble polyubiquitylated proteins from chromatin, membranes, macromolecular protein complexes and aggregates which are either degraded by the proteasome or recycled. p97 can use energy derived from ATP hydrolysis to catalyze substrate unfolding and threading through its central channel. The function of p97 in a large variety of different cellular contexts is reflected by its simultaneous association with different cofactors, which are involved in substrate recognition and processing, thus leading to the formation of transient multi-protein complexes. Dysregulation in protein homeostasis and proteotoxic stress are often involved in the development of cancer and neurological diseases and targeting the UPS including p97 in cancer is a well-established pharmacological strategy. In this chapter we will describe structural and functional aspects of the p97 interactome in regulating diverse cellular processes and will discuss the role of p97 in targeted cancer therapy.
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9
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Structure of the Cdc48 ATPase with its ubiquitin-binding cofactor Ufd1-Npl4. Nat Struct Mol Biol 2018; 25:616-622. [PMID: 29967539 PMCID: PMC6044470 DOI: 10.1038/s41594-018-0085-x] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 05/31/2018] [Indexed: 01/08/2023]
Abstract
Many poly-ubiquitinated proteins are extracted from membranes or complexes by a conserved ATPase, called Cdc48 in yeast and p97/VCP in mammals, before proteasomal degradation1. Each Cdc48 hexamer contains two stacked ATPase rings (D1 and D2) and six N-terminal (N) domains2. Cdc48 binds various cofactors, including a heterodimer of Ufd1 and Npl43. Here, we report structures of the Cdc48-Ufd1-Npl4 ATPase complex from Chaetomium thermophilum. Npl4 interacts through its UBX-like domain with a Cdc48 N domain, and uses two Zn2+-finger domains to anchor an enzymatically inactive Mpr1/Pad1 N-terminal (MPN) domain, homologous to domains found in several isopeptidases, to the top of the D1 ATPase ring. The MPN domain of Npl4 is located above Cdc48’s central pore, similarly to the MPN of the de-ubiquitinase Rpn11 in the proteasome4. Our results indicate that Npl4 is unique among Cdc48 cofactors, and suggest a mechanism for how poly-ubiquitinated substrates bind to and translocate into the ATPase.
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10
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Wu X, Rapoport TA. Mechanistic insights into ER-associated protein degradation. Curr Opin Cell Biol 2018; 53:22-28. [PMID: 29719269 DOI: 10.1016/j.ceb.2018.04.004] [Citation(s) in RCA: 231] [Impact Index Per Article: 38.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Revised: 04/11/2018] [Accepted: 04/11/2018] [Indexed: 12/16/2022]
Abstract
Misfolded proteins of the endoplasmic reticulum (ER) are discarded by a conserved process, called ER-associated protein degradation (ERAD). ERAD substrates are retro-translocated into the cytosol, polyubiquitinated, extracted from the ER membrane, and ultimately degraded by the proteasome. Recent in vitro experiments with purified components have given insight into the mechanism of ERAD. ERAD substrates with misfolded luminal or intramembrane domains are moved across the ER membrane through a channel formed by the multispanning ubiquitin ligase Hrd1. Following polyubiquitination, substrates are extracted from the membrane by the Cdc48/p97 ATPase complex and transferred to the proteasome. We discuss the molecular mechanism of these processes and point out remaining open questions.
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Affiliation(s)
- Xudong Wu
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, United States
| | - Tom A Rapoport
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, United States.
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11
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VCP/p97-Mediated Unfolding as a Principle in Protein Homeostasis and Signaling. Mol Cell 2017; 69:182-194. [PMID: 29153394 DOI: 10.1016/j.molcel.2017.10.028] [Citation(s) in RCA: 262] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 10/06/2017] [Accepted: 10/20/2017] [Indexed: 01/14/2023]
Abstract
The AAA+-type ATPase p97 governs an ever-expanding number of cellular processes reaching from degradation of damaged proteins and organelles to key signaling events and chromatin regulation with thousands of client proteins. With its relevance for cellular homeostasis and genome stability, it is linked to muscular and neuronal degeneration and, conversely, constitutes an attractive anti-cancer drug target. Its molecular function is ATP-driven protein unfolding, which is directed by ubiquitin and assisted by a host of cofactor proteins. This activity underlies p97's diverse ability to pull proteins out of membranes, unfold proteins for proteasomal degradation, or segregate proteins from partners for downstream activity. Recent advances in structural analysis and biochemical reconstitution have underscored this notion, resolved detailed molecular motions within the p97 hexamer, and suggested substrate threading through the central channel of the p97 hexamer as the driving mechanism. We will discuss the mechanisms and open questions in the context of the diverse cellular activities.
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12
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Byrne DJ, Harmon MJ, Simpson JC, Blackstone C, O'Sullivan NC. Roles for the VCP co-factors Npl4 and Ufd1 in neuronal function in Drosophila melanogaster. J Genet Genomics 2017; 44:493-501. [PMID: 29037990 PMCID: PMC5666124 DOI: 10.1016/j.jgg.2017.06.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 06/02/2017] [Accepted: 06/19/2017] [Indexed: 12/18/2022]
Abstract
The VCP-Ufd1-Npl4 complex regulates proteasomal processing within cells by delivering ubiquitinated proteins to the proteasome for degradation. Mutations in VCP are associated with two neurodegenerative diseases, amyotrophic lateral sclerosis (ALS) and inclusion body myopathy with Paget's disease of the bone and frontotemporal dementia (IBMPFD), and extensive study has revealed crucial functions of VCP within neurons. By contrast, little is known about the functions of Npl4 or Ufd1 in vivo. Using neuronal-specific knockdown of Npl4 or Ufd1 in Drosophila melanogaster, we infer that Npl4 contributes to microtubule organization within developing motor neurons. Moreover, Npl4 RNAi flies present with neurodegenerative phenotypes including progressive locomotor deficits, reduced lifespan and increased accumulation of TAR DNA-binding protein-43 homolog (TBPH). Knockdown, but not overexpression, of TBPH also exacerbates Npl4 RNAi-associated adult-onset neurodegenerative phenotypes. In contrast, we find that neuronal knockdown of Ufd1 has little effect on neuromuscular junction (NMJ) organization, TBPH accumulation or adult behaviour. These findings suggest the differing neuronal functions of Npl4 and Ufd1 in vivo.
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Affiliation(s)
- Dwayne J Byrne
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland
| | - Mark J Harmon
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland
| | - Jeremy C Simpson
- UCD School of Biology and Environmental Science, UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin 4, Ireland
| | - Craig Blackstone
- Cell Biology Section, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Niamh C O'Sullivan
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland.
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13
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Abstract
A conserved AAA+ ATPase, called Cdc48 in yeast and p97 or VCP in metazoans, plays an essential role in many cellular processes by segregating polyubiquitinated proteins from complexes or membranes. For example, in endoplasmic reticulum (ER)-associated protein degradation (ERAD), Cdc48/p97 pulls polyubiquitinated, misfolded proteins out of the ER and transfers them to the proteasome. Cdc48/p97 consists of an N-terminal domain and two ATPase domains (D1 and D2). Six Cdc48 monomers form a double-ring structure surrounding a central pore. Cdc48/p97 cooperates with a number of different cofactors, which bind either to the N-terminal domain or to the C-terminal tail. The mechanism of Cdc48/p97 action is poorly understood, despite its critical role in many cellular systems. Recent in vitro experiments using yeast Cdc48 and its heterodimeric cofactor Ufd1/Npl4 (UN) have resulted in novel mechanistic insight. After interaction of the substrate-attached polyubiquitin chain with UN, Cdc48 uses ATP hydrolysis in the D2 domain to move the polypeptide through its central pore, thereby unfolding the substrate. ATP hydrolysis in the D1 domain is involved in substrate release from the Cdc48 complex, which requires the cooperation of the ATPase with a deubiquitinase (DUB). Surprisingly, the DUB does not completely remove all ubiquitin molecules; the remaining oligoubiquitin chain is also translocated through the pore. Cdc48 action bears similarities to the translocation mechanisms employed by bacterial AAA ATPases and the eukaryotic 19S subunit of the proteasome, but differs significantly from that of a related type II ATPase, the NEM-sensitive fusion protein (NSF). Many questions about Cdc48/p97 remain unanswered, including how it handles well-folded substrate proteins, how it passes substrates to the proteasome, and how various cofactors modify substrates and regulate its function.
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Affiliation(s)
- Nicholas Bodnar
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Tom Rapoport
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, Boston, MA, USA
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14
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Ye Y, Tang WK, Zhang T, Xia D. A Mighty "Protein Extractor" of the Cell: Structure and Function of the p97/CDC48 ATPase. Front Mol Biosci 2017; 4:39. [PMID: 28660197 PMCID: PMC5468458 DOI: 10.3389/fmolb.2017.00039] [Citation(s) in RCA: 129] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 05/22/2017] [Indexed: 12/13/2022] Open
Abstract
p97/VCP (known as Cdc48 in S. cerevisiae or TER94 in Drosophila) is one of the most abundant cytosolic ATPases. It is highly conserved from archaebacteria to eukaryotes. In conjunction with a large number of cofactors and adaptors, it couples ATP hydrolysis to segregation of polypeptides from immobile cellular structures such as protein assemblies, membranes, ribosome, and chromatin. This often results in proteasomal degradation of extracted polypeptides. Given the diversity of p97 substrates, this "segregase" activity has profound influence on cellular physiology ranging from protein homeostasis to DNA lesion sensing, and mutations in p97 have been linked to several human diseases. Here we summarize our current understanding of the structure and function of this important cellular machinery and discuss the relevant clinical implications.
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Affiliation(s)
- Yihong Ye
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesda, MD, United States
| | - Wai Kwan Tang
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of HealthBethesda, MD, United States
| | - Ting Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesda, MD, United States
| | - Di Xia
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of HealthBethesda, MD, United States
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15
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Ubiquitin- and ATP-dependent unfoldase activity of P97/VCP•NPLOC4•UFD1L is enhanced by a mutation that causes multisystem proteinopathy. Proc Natl Acad Sci U S A 2017; 114:E4380-E4388. [PMID: 28512218 DOI: 10.1073/pnas.1706205114] [Citation(s) in RCA: 125] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
p97 is a "segregase" that plays a key role in numerous ubiquitin (Ub)-dependent pathways such as ER-associated degradation. It has been hypothesized that p97 extracts proteins from membranes or macromolecular complexes to enable their proteasomal degradation; however, the complex nature of p97 substrates has made it difficult to directly observe the fundamental basis for this activity. To address this issue, we developed a soluble p97 substrate-Ub-GFP modified with K48-linked ubiquitin chains-for in vitro p97 activity assays. We demonstrate that WT p97 can unfold proteins and that this activity is dependent on the p97 adaptor NPLOC4-UFD1L, ATP hydrolysis, and substrate ubiquitination, with branched chains providing maximal stimulation. Furthermore, we show that a p97 mutant that causes inclusion body myopathy, Paget's disease of bone, and frontotemporal dementia in humans unfolds substrate faster, suggesting that excess activity may underlie pathogenesis. This work overcomes a significant barrier in the study of p97 and will allow the future dissection of p97 mechanism at a level of detail previously unattainable.
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16
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Hänzelmann P, Schindelin H. The Interplay of Cofactor Interactions and Post-translational Modifications in the Regulation of the AAA+ ATPase p97. Front Mol Biosci 2017; 4:21. [PMID: 28451587 PMCID: PMC5389986 DOI: 10.3389/fmolb.2017.00021] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 03/24/2017] [Indexed: 12/18/2022] Open
Abstract
The hexameric type II AAA ATPase (ATPase associated with various activities) p97 (also referred to as VCP, Cdc48, and Ter94) is critically involved in a variety of cellular activities including pathways such as DNA replication and repair which both involve chromatin remodeling, and is a key player in various protein quality control pathways mediated by the ubiquitin proteasome system as well as autophagy. Correspondingly, p97 has been linked to various pathophysiological states including cancer, neurodegeneration, and premature aging. p97 encompasses an N-terminal domain, two highly conserved ATPase domains and an unstructured C-terminal tail. This enzyme hydrolyzes ATP and utilizes the resulting energy to extract or disassemble protein targets modified with ubiquitin from stable protein assemblies, chromatin and membranes. p97 participates in highly diverse cellular processes and hence its activity is tightly controlled. This is achieved by multiple regulatory cofactors, which either associate with the N-terminal domain or interact with the extreme C-terminus via distinct binding elements and target p97 to specific cellular pathways, sometimes requiring the simultaneous association with more than one cofactor. Most cofactors are recruited to p97 through conserved binding motifs/domains and assist in substrate recognition or processing by providing additional molecular properties. A tight control of p97 cofactor specificity and diversity as well as the assembly of higher-order p97-cofactor complexes is accomplished by various regulatory mechanisms, which include bipartite binding, binding site competition, changes in oligomeric assemblies, and nucleotide-induced conformational changes. Furthermore, post-translational modifications (PTMs) like acetylation, palmitoylation, phosphorylation, SUMOylation, and ubiquitylation of p97 have been reported which further modulate its diverse molecular activities. In this review, we will describe the molecular basis of p97-cofactor specificity/diversity and will discuss how PTMs can modulate p97-cofactor interactions and affect the physiological and patho-physiological functions of p97.
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Affiliation(s)
- Petra Hänzelmann
- Rudolf Virchow Center for Experimental Biomedicine, University of WürzburgWürzburg, Germany
| | - Hermann Schindelin
- Rudolf Virchow Center for Experimental Biomedicine, University of WürzburgWürzburg, Germany
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17
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Le LTM, Kang W, Kim JY, Le OTT, Lee SY, Yang JK. Structural Details of Ufd1 Binding to p97 and Their Functional Implications in ER-Associated Degradation. PLoS One 2016; 11:e0163394. [PMID: 27684549 PMCID: PMC5042407 DOI: 10.1371/journal.pone.0163394] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 09/06/2016] [Indexed: 11/18/2022] Open
Abstract
The hexameric ATPase p97 has been implicated in diverse cellular processes through interactions with many different adaptor proteins at its N-terminal domain. Among these, the Ufd1-Npl4 heterodimer is a major adaptor, and the p97-Ufd1-Npl4 complex plays an essential role in endoplasmic reticulum-associated degradation (ERAD), acting as a segregase that translocates the ubiquitinated client protein from the ER membrane into the cytosol for proteasomal degradation. We determined the crystal structure of the complex of the N-terminal domain of p97 and the SHP box of Ufd1 at a resolution of 1.55 Å. The 11-residue-long SHP box of Ufd1 binds at the far-most side of the Nc lobe of the p97 N domain primarily through hydrophobic interactions, such that F225, F228, N233 and L235 of the SHP box contact hydrophobic residues on the surface of the p97 Nc lobe. Mutating these key interface residues abolished the interactions in two different binding experiments, isothermal titration calorimetry and co-immunoprecipitation. Furthermore, cycloheximide chase assays showed that these same mutations caused accumulation of tyrosinase-C89R, a well-known ERAD substrate, thus implying decreased rate of protein degradation due to their defects in ERAD function. Together, these results provide structural and biochemical insights into the interaction between p97 N domain and Ufd1 SHP box.
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Affiliation(s)
- Le Thi My Le
- Department of Chemistry, College of Natural Sciences, Soongsil University, Seoul 156–743, Korea
| | - Wonchull Kang
- Department of Chemistry, College of Natural Sciences, Soongsil University, Seoul 156–743, Korea
| | - Ji-Yun Kim
- Department of Biomedical Sciences and Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, Suwon 443–721, Korea
| | - Oanh Thi Tu Le
- Department of Biomedical Sciences and Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, Suwon 443–721, Korea
| | - Sang Yoon Lee
- Department of Biomedical Sciences and Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, Suwon 443–721, Korea
- * E-mail: (JKY); (SYL)
| | - Jin Kuk Yang
- Department of Chemistry, College of Natural Sciences, Soongsil University, Seoul 156–743, Korea
- Department of Information Communication, Materials, and Chemistry Convergence Technology, Soongsil University, Seoul 156–743, Korea
- * E-mail: (JKY); (SYL)
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18
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Papadopoulou T, Richly H. On-site remodeling at chromatin: How multiprotein complexes are rebuilt during DNA repair and transcriptional activation. Bioessays 2016; 38:1130-1140. [PMID: 27599465 DOI: 10.1002/bies.201600094] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In this review, we discuss a novel on-site remodeling function that is mediated by the H2A-ubiquitin binding protein ZRF1. ZRF1 facilitates the remodeling of multiprotein complexes at chromatin and lies at the heart of signaling processes that occur at DNA damage sites and during transcriptional activation. In nucleotide excision repair ZRF1 remodels E3 ubiquitin ligase complexes at the damage site. During embryonic stem cell differentiation, it contributes to retinoic acid-mediated gene activation by altering the subunit composition of the Mediator complex. We postulate that ZRF1 operates in conjunction with cellular remodeling machines and suggest that on-site remodeling might be a hallmark of many chromatin-associated signaling pathways. We discuss yet unexplored functions of ZRF1-mediated remodeling in replication and double strand break repair. In conclusion, we postulate that on-site remodeling of multiprotein complexes is essential for the timing of chromatin signaling processes.
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Affiliation(s)
- Thaleia Papadopoulou
- Laboratory of Molecular Epigenetics, Institute of Molecular Biology (IMB), Mainz, Germany
| | - Holger Richly
- Laboratory of Molecular Epigenetics, Institute of Molecular Biology (IMB), Mainz, Germany.
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19
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Xia D, Tang WK, Ye Y. Structure and function of the AAA+ ATPase p97/Cdc48p. Gene 2016. [DOI: 10.1016/j.gene.2016.02.042 and 21=21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/01/2022]
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20
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Xia D, Tang WK, Ye Y. Structure and function of the AAA+ ATPase p97/Cdc48p. Gene 2016. [DOI: 10.1016/j.gene.2016.02.042 and 67=89] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2022]
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21
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Wu X, Li L, Jiang H. Doa1 targets ubiquitinated substrates for mitochondria-associated degradation. J Cell Biol 2016; 213:49-63. [PMID: 27044889 PMCID: PMC4828692 DOI: 10.1083/jcb.201510098] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2015] [Accepted: 03/02/2016] [Indexed: 02/07/2023] Open
Abstract
Wu et al. show that Doa1 recognizes and recruits ubiquitinated mitochondrial outer-membrane proteins to the Cdc48–proteasome degradation pathway. Doa1 deficiency sensitizes cells to mitochondrial oxidative stress. Mitochondria-associated degradation (MAD) mediated by the Cdc48 complex and proteasome degrades ubiquitinated mitochondrial outer-membrane proteins. MAD is critical for mitochondrial proteostasis, but it remains poorly characterized. We identified several mitochondrial Cdc48 substrates and developed a genetic screen assay to uncover regulators of the Cdc48-dependent MAD pathway. Surprisingly, we identified Doa1, a substrate-processing factor of Cdc48 that inhibits the degradation of some Cdc48 substrates, as a critical mediator of the turnover of mitochondrial Cdc48 substrates. Deletion of DOA1 causes the accumulation and mislocalization of substrates on mitochondria. Profiling of Cdc48 cofactors shows that Doa1 and Cdc48-Ufd1-Npl4 form a functional complex mediating MAD. Biochemically, Doa1 interacts with ubiquitinated substrates and facilitates substrate recruitment to the Cdc48-Ufd1-Npl4 complex. Functionally, Doa1 is critical for cell survival under mitochondrial oxidative stress, but not ER stress, conditions. Collectively, our results demonstrate the essential role of the Doa1–Cdc48-Ufd1-Npl4 complex in mitochondrial proteostasis and suggest that Doa1 plays dual roles on the Cdc48 complex.
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Affiliation(s)
- Xi Wu
- National Institute of Biological Sciences, Beijing 102206, China
| | - Lanlan Li
- National Institute of Biological Sciences, Beijing 102206, China
| | - Hui Jiang
- National Institute of Biological Sciences, Beijing 102206, China
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22
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Xia D, Tang WK, Ye Y. Structure and function of the AAA+ ATPase p97/Cdc48p. Gene 2016; 583:64-77. [PMID: 26945625 DOI: 10.1016/j.gene.2016.02.042] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Revised: 02/23/2016] [Accepted: 02/25/2016] [Indexed: 11/29/2022]
Abstract
p97 (also known as valosin-containing protein (VCP) in mammals or Cdc48p in Saccharomyces cerevisiae) is an evolutionarily conserved ATPase present in all eukaryotes and archaebacteria. In conjunction with a collection of cofactors and adaptors, p97/Cdc48p performs an array of biological functions mostly through modulating the stability of 'client' proteins. Using energy from ATP hydrolysis, p97/Cdc48p segregates these molecules from immobile cellular structures such as protein assemblies, membrane organelles, and chromatin. Consequently, the released polypeptides can be efficiently degraded by the ubiquitin proteasome system or recycled. This review summarizes our current understanding of the structure and function of this essential cellular chaperoning system.
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Affiliation(s)
- Di Xia
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, United States.
| | - Wai Kwan Tang
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, United States
| | - Yihong Ye
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, United States.
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23
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Hänzelmann P, Schindelin H. Characterization of an Additional Binding Surface on the p97 N-Terminal Domain Involved in Bipartite Cofactor Interactions. Structure 2015; 24:140-147. [PMID: 26712280 DOI: 10.1016/j.str.2015.10.027] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 10/29/2015] [Accepted: 10/30/2015] [Indexed: 01/20/2023]
Abstract
The type II AAA ATPase p97 interacts with a large number of cofactors that regulate its function by recruiting it to different cellular pathways. Most of the cofactors interact with the N-terminal (N) domain of p97, either via ubiquitin-like domains or short linear binding motifs. While some linear binding motifs form α helices, another group features short stretches of unstructured hydrophobic sequences as found in the so-called SHP (BS1, binding segment 1) motif. Here we present the crystal structure of a SHP-binding motif in complex with p97, which reveals a so far uncharacterized binding site on the p97 N domain that is different from the conserved binding surface of all other known p97 cofactors. This finding explains how cofactors like UFD1/NPL4 and p47 can utilize a bipartite binding mechanism to interact simultaneously with the same p97 monomer via their ubiquitin-like domain and SHP motif.
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Affiliation(s)
- Petra Hänzelmann
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Straße 2, 97080 Würzburg, Germany.
| | - Hermann Schindelin
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Straße 2, 97080 Würzburg, Germany
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24
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Barthelme D, Sauer RT. Origin and Functional Evolution of the Cdc48/p97/VCP AAA+ Protein Unfolding and Remodeling Machine. J Mol Biol 2015; 428:1861-9. [PMID: 26608813 DOI: 10.1016/j.jmb.2015.11.015] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 11/03/2015] [Accepted: 11/16/2015] [Indexed: 01/25/2023]
Abstract
The AAA+ Cdc48 ATPase (alias p97 or VCP) is a key player in multiple ubiquitin-dependent cell signaling, degradation, and quality control pathways. Central to these broad biological functions is the ability of Cdc48 to interact with a large number of adaptor proteins and to remodel macromolecular proteins and their complexes. Different models have been proposed to explain how Cdc48 might couple ATP hydrolysis to forcible unfolding, dissociation, or remodeling of cellular clients. In this review, we provide an overview of possible mechanisms for substrate unfolding/remodeling by this conserved and essential AAA+ protein machine and their adaption and possible biological function throughout evolution.
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Affiliation(s)
- Dominik Barthelme
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Max Planck Institute for Infection Biology, Berlin 10117, Germany
| | - Robert T Sauer
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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25
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Mountassif D, Fabre L, Zaid Y, Halawani D, Rouiller I. Cryo-EM of the pathogenic VCP variant R155P reveals long-range conformational changes in the D2 ATPase ring. Biochem Biophys Res Commun 2015; 468:636-41. [PMID: 26549226 DOI: 10.1016/j.bbrc.2015.11.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 11/02/2015] [Indexed: 11/25/2022]
Abstract
Single amino acid mutations in valosin containing protein (VCP/p97), a highly conserved member of the ATPases associated with diverse cellular activities (AAA) family of ATPases has been linked to a severe degenerative disease affecting brain, muscle and bone tissue. Previous studies have demonstrated the role of VCP mutations in altering the ATPase activity of the D2 ring; however the structural consequences of these mutations remain unclear. In this study, we report the three-dimensional (3D) map of the pathogenic VCP variant, R155P, as revealed by single-particle Cryo-Electron Microscopy (EM) analysis at 14 Å resolution. We show that the N-terminal R155P mutation induces a large structural reorganisation of the D2 ATPase ring. Results from docking studies using crystal structure data of available wild-type VCP in the EM density maps indicate that the major difference is localized at the interface between two protomers within the D2 ring. Consistent with a conformational change, the VCP R155P variant shifted the isoelectric point of the protein and reduced its interaction with its well-characterized cofactor, nuclear protein localization-4 (Npl4). Together, our results demonstrate that a single amino acid substitution in the N-terminal domain can relay long-range conformational changes to the distal D2 ATPase ring. Our results provide the first structural clues of how VCP mutations may influence the activity and function of the D2 ATPase ring.
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Affiliation(s)
- Driss Mountassif
- Department of Anatomy and Cell Biology, McGill University, Groupe de recherche axé sur la structure des protéines (GRASP), Groupe d'Étude des Proteines Membranaires (GÉPROM), 3640 University Street, Montreal H3A 0C7, Canada
| | - Lucien Fabre
- Department of Anatomy and Cell Biology, McGill University, Groupe de recherche axé sur la structure des protéines (GRASP), Groupe d'Étude des Proteines Membranaires (GÉPROM), 3640 University Street, Montreal H3A 0C7, Canada
| | - Younes Zaid
- Department of Anatomy and Cell Biology, McGill University, Groupe de recherche axé sur la structure des protéines (GRASP), Groupe d'Étude des Proteines Membranaires (GÉPROM), 3640 University Street, Montreal H3A 0C7, Canada; Current address: Laboratory of Thrombosis and Hemostasis, Montreal Heart Institute, Montreal, Quebec, Canada
| | - Dalia Halawani
- Department of Anatomy and Cell Biology, McGill University, Groupe de recherche axé sur la structure des protéines (GRASP), Groupe d'Étude des Proteines Membranaires (GÉPROM), 3640 University Street, Montreal H3A 0C7, Canada; Current address: Department of Cell Biology, Lerner Research Institute, 9500 Euclid Avenue NC10, Cleveland, OH 44195, USA
| | - Isabelle Rouiller
- Department of Anatomy and Cell Biology, McGill University, Groupe de recherche axé sur la structure des protéines (GRASP), Groupe d'Étude des Proteines Membranaires (GÉPROM), 3640 University Street, Montreal H3A 0C7, Canada.
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26
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Structural and Computational Biology in the Design of Immunogenic Vaccine Antigens. J Immunol Res 2015; 2015:156241. [PMID: 26526043 PMCID: PMC4615220 DOI: 10.1155/2015/156241] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 08/02/2015] [Indexed: 01/08/2023] Open
Abstract
Vaccination is historically one of the most important medical interventions for the prevention of infectious disease. Previously, vaccines were typically made of rather crude mixtures of inactivated or attenuated causative agents. However, over the last 10–20 years, several important technological and computational advances have enabled major progress in the discovery and design of potently immunogenic recombinant protein vaccine antigens. Here we discuss three key breakthrough approaches that have potentiated structural and computational vaccine design. Firstly, genomic sciences gave birth to the field of reverse vaccinology, which has enabled the rapid computational identification of potential vaccine antigens. Secondly, major advances in structural biology, experimental epitope mapping, and computational epitope prediction have yielded molecular insights into the immunogenic determinants defining protective antigens, enabling their rational optimization. Thirdly, and most recently, computational approaches have been used to convert this wealth of structural and immunological information into the design of improved vaccine antigens. This review aims to illustrate the growing power of combining sequencing, structural and computational approaches, and we discuss how this may drive the design of novel immunogens suitable for future vaccines urgently needed to increase the global prevention of infectious disease.
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27
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Control of p97 function by cofactor binding. FEBS Lett 2015; 589:2578-89. [PMID: 26320413 DOI: 10.1016/j.febslet.2015.08.028] [Citation(s) in RCA: 164] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Revised: 08/18/2015] [Accepted: 08/18/2015] [Indexed: 12/14/2022]
Abstract
p97 (also known as Cdc48, Ter94, and VCP) is an essential, abundant and highly conserved ATPase driving the turnover of ubiquitylated proteins in eukaryotes. Even though p97 is involved in highly diverse cellular pathways and processes, it exhibits hardly any substrate specificity on its own. Instead, it relies on a large number of regulatory cofactors controlling substrate specificity and turnover. The complexity as well as temporal and spatial regulation of the interactions between p97 and its cofactors is only beginning to be understood at the molecular level. Here, we give an overview on the structural framework of p97 interactions with its cofactors, the emerging principles underlying the assembly of complexes with different cofactors, and the pathogenic effects of disease-associated p97 mutations on cofactor binding.
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28
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Gardner BM, Chowdhury S, Lander GC, Martin A. The Pex1/Pex6 complex is a heterohexameric AAA+ motor with alternating and highly coordinated subunits. J Mol Biol 2015; 427:1375-1388. [PMID: 25659908 DOI: 10.1016/j.jmb.2015.01.019] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Revised: 01/23/2015] [Accepted: 01/24/2015] [Indexed: 12/13/2022]
Abstract
Pex1 and Pex6 are Type-2 AAA+ ATPases required for the de novo biogenesis of peroxisomes. Mutations in Pex1 and Pex6 account for the majority of the most severe forms of peroxisome biogenesis disorders in humans. Here, we show that the ATP-dependent complex of Pex1 and Pex6 from Saccharomyces cerevisiae is a heterohexamer with alternating subunits. Within the Pex1/Pex6 complex, only the D2 ATPase ring hydrolyzes ATP, while nucleotide binding in the D1 ring promotes complex assembly. ATP hydrolysis by Pex1 is highly coordinated with that of Pex6. Furthermore, Pex15, the membrane anchor required for Pex1/Pex6 recruitment to peroxisomes, inhibits the ATP-hydrolysis activity of Pex1/Pex6.
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Affiliation(s)
- Brooke M Gardner
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200, USA; Miller Institute for Basic Research in Science, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Saikat Chowdhury
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Gabriel C Lander
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Andreas Martin
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3200, USA; California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720-3220, USA.
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29
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Marinova IN, Engelbrecht J, Ewald A, Langholm LL, Holmberg C, Kragelund BB, Gordon C, Nielsen O, Hartmann-Petersen R. Single site suppressors of a fission yeast temperature-sensitive mutant in cdc48 identified by whole genome sequencing. PLoS One 2015; 10:e0117779. [PMID: 25658828 PMCID: PMC4319823 DOI: 10.1371/journal.pone.0117779] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2014] [Accepted: 12/30/2014] [Indexed: 12/29/2022] Open
Abstract
The protein called p97 in mammals and Cdc48 in budding and fission yeast is a homo-hexameric, ring-shaped, ubiquitin-dependent ATPase complex involved in a range of cellular functions, including protein degradation, vesicle fusion, DNA repair, and cell division. The cdc48+ gene is essential for viability in fission yeast, and point mutations in the human orthologue have been linked to disease. To analyze the function of p97/Cdc48 further, we performed a screen for cold-sensitive suppressors of the temperature-sensitive cdc48-353 fission yeast strain. In total, 29 independent pseudo revertants that had lost the temperature-sensitive growth defect of the cdc48-353 strain were isolated. Of these, 28 had instead acquired a cold-sensitive phenotype. Since the suppressors were all spontaneous mutants, and not the result of mutagenesis induced by chemicals or UV irradiation, we reasoned that the genome sequences of the 29 independent cdc48-353 suppressors were most likely identical with the exception of the acquired suppressor mutations. This prompted us to test if a whole genome sequencing approach would allow us to map the mutations. Indeed genome sequencing unambiguously revealed that the cold-sensitive suppressors were all second site intragenic cdc48 mutants. Projecting these onto the Cdc48 structure revealed that while the original temperature-sensitive G338D mutation is positioned near the central pore in the hexameric ring, the suppressor mutations locate to subunit-subunit and inter-domain boundaries. This suggests that Cdc48-353 is structurally compromized at the restrictive temperature, but re-established in the suppressor mutants. The last suppressor was an extragenic frame shift mutation in the ufd1 gene, which encodes a known Cdc48 co-factor. In conclusion, we show, using a novel whole genome sequencing approach, that Cdc48-353 is structurally compromized at the restrictive temperature, but stabilized in the suppressors.
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Affiliation(s)
- Irina N. Marinova
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Jacob Engelbrecht
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Adrian Ewald
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Lasse L. Langholm
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | | | | | - Colin Gordon
- MRC Human Genetics Unit, Western General Hospital, Edinburgh, Scotland, United Kingdom
| | - Olaf Nielsen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
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30
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Kashima I, Takahashi M, Hashimoto Y, Sakota E, Nakamura Y, Inada T. A functional involvement of ABCE1, eukaryotic ribosome recycling factor, in nonstop mRNA decay in Drosophila melanogaster cells. Biochimie 2014; 106:10-6. [DOI: 10.1016/j.biochi.2014.08.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 08/02/2014] [Indexed: 11/25/2022]
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31
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Förster F, Schuller JM, Unverdorben P, Aufderheide A. Emerging mechanistic insights into AAA complexes regulating proteasomal degradation. Biomolecules 2014; 4:774-94. [PMID: 25102382 PMCID: PMC4192671 DOI: 10.3390/biom4030774] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 06/11/2014] [Accepted: 07/21/2014] [Indexed: 12/25/2022] Open
Abstract
The 26S proteasome is an integral element of the ubiquitin-proteasome system (UPS) and, as such, responsible for regulated degradation of proteins in eukaryotic cells. It consists of the core particle, which catalyzes the proteolysis of substrates into small peptides, and the regulatory particle, which ensures specificity for a broad range of substrates. The heart of the regulatory particle is an AAA-ATPase unfoldase, which is surrounded by non-ATPase subunits enabling substrate recognition and processing. Cryo-EM-based studies revealed the molecular architecture of the 26S proteasome and its conformational rearrangements, providing insights into substrate recognition, commitment, deubiquitylation and unfolding. The cytosol proteasomal degradation of polyubiquitylated substrates is tuned by various associating cofactors, including deubiquitylating enzymes, ubiquitin ligases, shuttling ubiquitin receptors and the AAA-ATPase Cdc48/p97. Cdc48/p97 and its cofactors function upstream of the 26S proteasome, and their modular organization exhibits some striking analogies to the regulatory particle. In archaea PAN, the closest regulatory particle homolog and Cdc48 even have overlapping functions, underscoring their intricate relationship. Here, we review recent insights into the structure and dynamics of the 26S proteasome and its associated machinery, as well as our current structural knowledge on the Cdc48/p97 and its cofactors that function in the ubiquitin-proteasome system (UPS).
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Affiliation(s)
- Friedrich Förster
- Department of Molecular Structural Biology, Max-Planck Institute of Biochemistry, Martinsried D-82152, Germany.
| | - Jan M Schuller
- Department of Molecular Structural Biology, Max-Planck Institute of Biochemistry, Martinsried D-82152, Germany.
| | - Pia Unverdorben
- Department of Molecular Structural Biology, Max-Planck Institute of Biochemistry, Martinsried D-82152, Germany.
| | - Antje Aufderheide
- Department of Molecular Structural Biology, Max-Planck Institute of Biochemistry, Martinsried D-82152, Germany.
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32
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Kim SJ, Kim EE. Crystallization and preliminary X-ray crystallographic analysis of the complex between the N-D1 domain of VCP from Homo sapiens and the N domain of OTU1 from Saccharomyces cerevisiae. Acta Crystallogr F Struct Biol Commun 2014; 70:1087-9. [PMID: 25084388 PMCID: PMC4118810 DOI: 10.1107/s2053230x14013351] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 06/07/2014] [Indexed: 01/13/2023] Open
Abstract
VCP (valosin-containing protein; also known as p97) plays important roles in many biological processes including the ERAD (endoplasmic reticulum-associated degradation) pathway and its function is governed by binding partners. OTU1 (ovarian tumour domain-containing protein 1) is a recently discovered deubiquitinating enzyme that interacts directly with VCP in the ERAD pathway. In order to understand the interactions between the two proteins, the N-D1 domain of VCP and the UBXL domain of OTU1 were cloned, overexpressed, purified and crystallized. The crystals of the complex diffracted to 3.25 Å resolution and belonged to space group P21, with unit-cell parameters a = 165.45, b = 176.73, c = 165.59 Å, β = 120.095°. There are two molecules of the complex in the asymmetric unit with a Matthews coefficient of 2.62 Å(3) Da(-1) and a solvent content of 53%.
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Affiliation(s)
- Su Jin Kim
- Biomedical Research Institute, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea
| | - Eunice EunKyeong Kim
- Biomedical Research Institute, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea
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33
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Ewens CA, Panico S, Kloppsteck P, McKeown C, Ebong IO, Robinson C, Zhang X, Freemont PS. The p97-FAF1 protein complex reveals a common mode of p97 adaptor binding. J Biol Chem 2014; 289:12077-12084. [PMID: 24619421 PMCID: PMC4002113 DOI: 10.1074/jbc.m114.559591] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 03/05/2014] [Indexed: 01/07/2023] Open
Abstract
p97, also known as valosin-containing protein, is a versatile participant in the ubiquitin-proteasome system. p97 interacts with a large network of adaptor proteins to process ubiquitylated substrates in different cellular pathways, including endoplasmic reticulum-associated degradation and transcription factor activation. p97 and its adaptor Fas-associated factor-1 (FAF1) both have roles in the ubiquitin-proteasome system during NF-κB activation, although the mechanisms are unknown. FAF1 itself also has emerging roles in other cell-cycle pathways and displays altered expression levels in various cancer cell lines. We have performed a detailed study the p97-FAF1 interaction. We show that FAF1 binds p97 stably and in a stoichiometry of 3 to 6. Cryo-EM analysis of p97-FAF1 yielded a 17 Å reconstruction of the complex with FAF1 above the p97 ring. Characteristics of p97-FAF1 uncovered in this study reveal common features in the interactions of p97, providing mechanistic insight into how p97 mediates diverse functionalities.
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Affiliation(s)
- Caroline A Ewens
- Centre for Structural Biology, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Silvia Panico
- Centre for Structural Biology, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Patrik Kloppsteck
- Centre for Structural Biology, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Ciaran McKeown
- Centre for Structural Biology, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Ima-Obong Ebong
- Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3TA, United Kingdom
| | - Carol Robinson
- Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3TA, United Kingdom
| | - Xiaodong Zhang
- Centre for Structural Biology, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Paul S Freemont
- Centre for Structural Biology, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom.
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34
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Kim SJ, Cho J, Song EJ, Kim SJ, Kim HM, Lee KE, Suh SW, Kim EE. Structural basis for ovarian tumor domain-containing protein 1 (OTU1) binding to p97/valosin-containing protein (VCP). J Biol Chem 2014; 289:12264-74. [PMID: 24610782 DOI: 10.1074/jbc.m113.523936] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Valosin-containing protein (VCP), also known as p97, is an AAA(+) ATPase that plays an essential role in a broad array of cellular processes including the endoplasmic reticulum-associated degradation (ERAD) pathway. Recently, ERAD-specific deubiquitinating enzymes have been reported to be physically associated with VCP, although the exact mechanism is not yet clear. Among these enzymes is ovarian tumor domain-containing protein 1 (OTU1). Here, we report the structural basis for interaction between VCP and OTU1. The crystal structure of the ubiquitin regulatory X-like (UBXL) domain of OTU1 (UBXLOTU1) complexed to the N-terminal domain of VCP (NVCP) at 1.8-Å resolution reveals that UBXLOTU1 adopts a ubiquitin-like fold and binds at the interface of two subdomains of NVCP using the (39)GYPP(42) loop of UBXLOTU1 with the two prolines in cis- and trans-configurations, respectively. A mutagenesis study shows that this loop is not only critical for the interaction with VCP but also for its role in the ERAD pathway. Negative staining EM shows that one molecule of OTU1 binds to one VCP hexamer, and isothermal titration calorimetry suggests that the two proteins bind with a KD of 0.71 μM. Analytical size exclusion chromatography and isothermal titration calorimetry demonstrates that OTU1 can bind VCP in both the presence and absence of a heterodimer formed by ubiquitin fusion degradation protein 1 and nuclear localization protein 4.
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Affiliation(s)
- Su Jin Kim
- From the Biomedical Research Institute, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea
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35
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Yeung HO, Förster A, Bebeacua C, Niwa H, Ewens C, McKeown C, Zhang X, Freemont PS. Inter-ring rotations of AAA ATPase p97 revealed by electron cryomicroscopy. Open Biol 2014; 4:130142. [PMID: 24598262 PMCID: PMC3971404 DOI: 10.1098/rsob.130142] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The type II AAA+ protein p97 is involved in numerous cellular activities, including endoplasmic reticulum-associated degradation, transcription activation, membrane fusion and cell-cycle control. These activities are at least in part regulated by the ubiquitin system, in which p97 is thought to target ubiquitylated protein substrates within macromolecular complexes and assist in their extraction or disassembly. Although ATPase activity is essential for p97 function, little is known about how ATP binding or hydrolysis is coupled with p97 conformational changes and substrate remodelling. Here, we have used single-particle electron cryomicroscopy (cryo-EM) to study the effect of nucleotides on p97 conformation. We have identified conformational heterogeneity within the cryo-EM datasets from which we have resolved two major p97 conformations. A comparison of conformations reveals inter-ring rotations upon nucleotide binding and hydrolysis that may be linked to the remodelling of target protein complexes.
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Affiliation(s)
- Heidi O Yeung
- Centre for Structural Biology, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
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36
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Platta HW, Hagen S, Reidick C, Erdmann R. The peroxisomal receptor dislocation pathway: to the exportomer and beyond. Biochimie 2013; 98:16-28. [PMID: 24345375 DOI: 10.1016/j.biochi.2013.12.009] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 12/05/2013] [Indexed: 12/29/2022]
Abstract
The biogenesis of peroxisomes is an ubiquitin-dependent process. In particular, the import of matrix proteins into the peroxisomal lumen requires the modification of import receptors with ubiquitin. The matrix proteins are synthesized on free polyribosomes in the cytosol and are recognized by import receptors via a peroxisomal targeting sequence (PTS). Subsequent to the transport of the receptor/cargo-complex to the peroxisomal membrane and the release of the cargo into the peroxisomal lumen, the PTS-receptors are exported back to the cytosol for further rounds of matrix protein import. The exportomer represents the molecular machinery required for the retrotranslocation of the PTS-receptors. It comprises enzymes for the ubiquitination as well as for the ATP-dependent extraction of the PTS-receptors from the peroxisomal membrane. Furthermore, recent evidence indicates a mechanistic interconnection of the ATP-dependent removal of the PTS-receptors with the translocation of the matrix protein into the organellar lumen. Interestingly, the components of the peroxisomal exportomer seem also to be involved in cellular tasks that are distinct from the ubiquitination and dislocation of the peroxisomal PTS-receptors. This includes work that indicates a central function of this machinery in the export of peroxisomal matrix proteins in plants, while a subset of exportomer components is involved in the meiocyte formation in some fungi, the peroxisome-chloroplast contact during photorespiration in plants and possibly even the selective degradation of peroxisomes via pexophagy. In this review, we want to discuss the central role of the exportomer during matrix protein import, but also highlight distinct roles of exportomer constituents in additional cellular processes. This article is part of a Special Issue entitled: Peroxisomes: biogenesis, functions and diseases.
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Affiliation(s)
- Harald W Platta
- Biochemie Intrazellulärer Transportprozesse, Ruhr-Universität Bochum, Universitätsstr. 150, D-44780 Bochum, Germany.
| | - Stefanie Hagen
- Systembiochemie, Ruhr-Universität Bochum, Universitätsstr. 150, D-44780 Bochum, Germany
| | - Christina Reidick
- Biochemie Intrazellulärer Transportprozesse, Ruhr-Universität Bochum, Universitätsstr. 150, D-44780 Bochum, Germany
| | - Ralf Erdmann
- Systembiochemie, Ruhr-Universität Bochum, Universitätsstr. 150, D-44780 Bochum, Germany.
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37
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Matsuda R, Ikeuchi K, Nomura S, Inada T. Protein quality control systems associated with no-go and nonstop mRNA surveillance in yeast. Genes Cells 2013; 19:1-12. [PMID: 24261871 DOI: 10.1111/gtc.12106] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2013] [Accepted: 09/19/2013] [Indexed: 11/28/2022]
Abstract
Quality control systems eliminate aberrant proteins derived from aberrant mRNAs. Two E3 ubiquitin ligases, Ltn1 and Not4, are involved in proteasomal protein degradation coupled to translation arrest. Here, we evaluated nonstop and translation arrest products degraded in a poly(A) tail-independent manner. Ltn1 was found to degrade aberrant nonstop polypeptides derived from nonstop mRNA lacking a termination codon, but not peptidyl-tRNA, even in the absence of the ribosome dissociation complex Dom34:Hbs1. The receptor for activated C kinase (RACK1/ASC1) was identified as a factor required for nascent peptide-dependent translation arrest as well as Ltn1-dependent protein degradation. Both Not4 and Ltn1 were involved in the degradation of various arrest products in a poly(A) tail-independent manner. Furthermore, carboxyl terminus-truncated degradation intermediates of arrest products were stabilized in a cdc48-3 mutant defective in unfolding or the disassembly related to proteasomal degradation. Thus, we propose that stalled ribosomes may be dissociated into subunits and that peptidyl-tRNA on the 60S subunit is ubiquitinated by Ltn1 and Cdc48 is required for the degradation following release from tRNA.
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Affiliation(s)
- Ryo Matsuda
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, 980-8578, Japan
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38
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Liu S, Yang H, Zhao J, Zhang YH, Song AX, Hu HY. NEDD8 ultimate buster-1 long (NUB1L) protein promotes transfer of NEDD8 to proteasome for degradation through the P97UFD1/NPL4 complex. J Biol Chem 2013; 288:31339-49. [PMID: 24019527 DOI: 10.1074/jbc.m113.484816] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The NEDD8 protein and neddylation levels in cells are modulated by NUB1L or NUB1 through proteasomal degradation, but the underlying molecular mechanism is not well understood. Here, we report that NUB1L down-regulated the protein levels of NEDD8 and neddylation through specifically recognizing NEDD8 and P97/VCP. NUB1L directly interacted with NEDD8, but not with ubiquitin, on the key residue Asn-51 of NEDD8 and with P97/VCP on its positively charged VCP binding motif. In coordination with the P97-UFD1-NPL4 complex (P97(UFD1/NPL4)), NUB1L promotes transfer of NEDD8 to proteasome for degradation. This mechanism is also exemplified by the canonical neddylation of cullin 1 for SCF (SKP1-cullin1-F-box) ubiquitin E3 ligases that is exquisitely regulated by the turnover of NEDD8.
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Affiliation(s)
- Shuai Liu
- From the State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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39
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Platta HW, Hagen S, Erdmann R. The exportomer: the peroxisomal receptor export machinery. Cell Mol Life Sci 2013; 70:1393-411. [PMID: 22983384 PMCID: PMC11113987 DOI: 10.1007/s00018-012-1136-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2012] [Revised: 07/30/2012] [Accepted: 08/13/2012] [Indexed: 12/21/2022]
Abstract
Peroxisomes constitute a dynamic compartment of almost all eukaryotic cells. Depending on environmental changes and cellular demands peroxisomes can acquire diverse metabolic roles. The compartmentalization of peroxisomal matrix enzymes is a prerequisite to carry out their physiologic function. The matrix proteins are synthesized on free ribosomes in the cytosol and are ferried to the peroxisomal membrane by specific soluble receptors. Subsequent to cargo release into the peroxisomal matrix, the receptors are exported back to the cytosol to facilitate further rounds of matrix protein import. This dislocation step is accomplished by a remarkable machinery, which comprises enzymes required for the ubiquitination as well as the ATP-dependent extraction of the receptor from the membrane. Interestingly, receptor ubiquitination and dislocation are the only known energy-dependent steps in the peroxisomal matrix protein import process. The current view is that the export machinery of the receptors might function as molecular motor not only in the dislocation of the receptors but also in the import step of peroxisomal matrix protein by coupling ATP-dependent removal of the peroxisomal import receptor with cargo translocation into the organelle. In this review we will focus on the architecture and function of the peroxisomal receptor export machinery, the peroxisomal exportomer.
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Affiliation(s)
- Harald W. Platta
- Abteilung für Systembiochemie, Medizinische Fakultät der Ruhr-Universität Bochum, Ruhr-Universität Bochum, Universitätsstr. 150, 44780 Bochum, Germany
| | - Stefanie Hagen
- Abteilung für Systembiochemie, Medizinische Fakultät der Ruhr-Universität Bochum, Ruhr-Universität Bochum, Universitätsstr. 150, 44780 Bochum, Germany
| | - Ralf Erdmann
- Abteilung für Systembiochemie, Medizinische Fakultät der Ruhr-Universität Bochum, Ruhr-Universität Bochum, Universitätsstr. 150, 44780 Bochum, Germany
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40
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Chia WS, Chia DX, Rao F, Bar Nun S, Geifman Shochat S. ATP binding to p97/VCP D1 domain regulates selective recruitment of adaptors to its proximal N-domain. PLoS One 2012; 7:e50490. [PMID: 23226521 PMCID: PMC3513293 DOI: 10.1371/journal.pone.0050490] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Accepted: 10/23/2012] [Indexed: 11/18/2022] Open
Abstract
p97/Valosin-containing protein (VCP) is a member of the AAA-ATPase family involved in many cellular processes including cell division, intracellular trafficking and extraction of misfolded proteins in endoplasmic reticulum-associated degradation (ERAD). It is a homohexamer with each subunit containing two tandem D1 and D2 ATPase domains and N- and C-terminal regions that function as adaptor protein binding domains. p97/VCP is directed to its many different functional pathways by associating with various adaptor proteins. The regulation of the recruitment of the adaptor proteins remains unclear. Two adaptor proteins, Ufd1/Npl4 and p47, which bind exclusively to the p97/VCP N-domain and direct p97/VCP to either ERAD-related processes or homotypic fusion of Golgi fragments, were studied here. Surface plasmon resonance biosensor-based assays allowed the study of binding kinetics in real time. In competition experiments, it was observed that in the presence of ATP, Ufd1/Npl4 was able to compete more effectively with p47 for binding to p97/VCP. By using non-hydrolysable ATP analogues and the hexameric truncated p97/N-D1 fragment, it was shown that binding rather than hydrolysis of ATP to the proximal D1 domain strengthened the Ufd1/Npl4 association with the N-domain, thus regulating the recruitment of either Ufd1/Npl4 or p47. This novel role of ATP and an assigned function to the D1 AAA-ATPase domain link the multiple functions of p97/VCP to the metabolic status of the cell.
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Affiliation(s)
- Wei Sheng Chia
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Diana Xueqi Chia
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Feng Rao
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Shoshana Bar Nun
- Department of Biochemistry and Molecular Biology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Susana Geifman Shochat
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
- * E-mail:
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41
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Dantuma NP, Hoppe T. Growing sphere of influence: Cdc48/p97 orchestrates ubiquitin-dependent extraction from chromatin. Trends Cell Biol 2012; 22:483-91. [PMID: 22818974 DOI: 10.1016/j.tcb.2012.06.003] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 06/14/2012] [Accepted: 06/18/2012] [Indexed: 11/30/2022]
Abstract
The AAA (ATPases associated with various cellular activities) family member Cdc48/p97 is best known for its role in ubiquitin-dependent proteasomal degradation of aberrant endoplasmic reticulum (ER) proteins, a process known as ER-associated degradation (ERAD). However, recent studies have also defined Cdc48/p97 as a central player in various chromatin-associated processes linked to cell cycle progression, DNA replication, transcription, and the DNA damage response. Notwithstanding the apparent differences in location and function, the role of Cdc48/p97 in ubiquitin-dependent extraction from chromatin (UDEC) bears striking similarities with its action in ERAD. Here, we discuss recent data that expand our current model of the role of Cdc48/p97 as a ubiquitin-selective segregase in the nuclear chromatin environment.
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Affiliation(s)
- Nico P Dantuma
- Department of Cell and Molecular Biology, Karolinska Institutet, von Eulers väg 3, S-17177 Stockholm, Sweden.
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42
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Tang WK, Xia D. Structural and functional deviations in disease-associated p97 mutants. J Struct Biol 2012; 179:83-92. [PMID: 22579784 DOI: 10.1016/j.jsb.2012.04.024] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 04/23/2012] [Accepted: 04/28/2012] [Indexed: 11/28/2022]
Abstract
Missense mutations that occur at the interface between two functional domains in the AAA protein p97 lead to suboptimal performance in its enzymatic activity and impaired intracellular functions, causing human disorders such as inclusion body myopathy associated with Paget's disease of the bone and frontotemporal dementia (IBMPFD). Much progress has been made in characterizing these mutants at cellular, sub-cellular and molecular levels, gaining a substantial understanding of the involvement of p97 in various cellular pathways. At the tissue level, patient biopsies revealed co-localization of p97 with pathologic proteineous inclusions and rimmed vacuoles, which can be reproduced in various cellular and animal models of IBMPFD. At the subcellular level, alterations in p97's ability to bind various adaptor proteins have been demonstrated for some but not all binding partners. Biochemical and biophysical characterizations of pathogenic p97 revealed altered nucleotide binding properties in the D1-domains compared to the wild type. Structural studies showed that mutant p97 are capable of undergoing a uniform transition in the N-domain from a Down- to an Up-conformation in the presence of ATPγS, while in the wild-type p97, this conformational change can only be demonstrated in solutions but not in crystals. These structural and biochemical analyses of IBMPFD mutants shed new light into the mechanism of p97 function.
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Affiliation(s)
- Wai Kwan Tang
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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