1
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Kueck AF, van den Boom J, Koska S, Ron D, Meyer H. Alternating binding and p97-mediated dissociation of SDS22 and I3 recycles active PP1 between holophosphatases. Proc Natl Acad Sci U S A 2024; 121:e2408787121. [PMID: 39207734 DOI: 10.1073/pnas.2408787121] [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: 05/02/2024] [Accepted: 07/16/2024] [Indexed: 09/04/2024] Open
Abstract
Protein phosphatase-1 catalytic subunit (PP1) joins diverse targeting subunits to form holophosphatases that regulate many cellular processes. Newly synthesized PP1 is known to be transiently sequestered in an inhibitory complex with Suppressor-of-Dis2-number-2 (SDS22) and Inhibitor-3 (I3), which is disassembled by the ATPases Associated with diverse cellular Activities plus (AAA+) protein p97. Here, we show that the SDS22-PP1-I3 complex also acts as a thermodynamic sink for mature PP1 and that cycles of SDS22-PP1-I3 formation and p97-driven disassembly regulate PP1 function and subunit exchange beyond PP1 biogenesis. Förster Resonance energy transfer (FRET) analysis of labeled proteins in vitro revealed that in the p97-mediated disassembly step, both SDS22 and I3 dissociate concomitantly, releasing PP1. In presence of a targeting subunit, for instance Growth Arrest and DNA Damage-inducible protein 34 (GADD34), liberated PP1 formed an active holophosphatase that dephosphorylated its substrate, eukaryotic translation initiation factor 2 alpha (eIF2α). Inhibition of p97 results in displacement of the GADD34 targeting subunit by rebinding of PP1 to SDS22 and I3 indicating that the SDS22-PP1-I3 complex is thermodynamically favored. Likewise, p97 inhibition in cells causes rapid sequestration of PP1 by free SDS22 and I3 at the expense of other subunits. This suggests that PP1 exists in a steady state maintained by spontaneous SDS22-PP1-I3 formation and adenosine triphosphate (ATP) hydrolysis, p97-driven disassembly that recycles active PP1 between different holophosphatase complexes to warrant a dynamic holophosphatase landscape.
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Affiliation(s)
- Anja F Kueck
- Molecular Biology I, Center of Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, 45141 Essen, Germany
| | - Johannes van den Boom
- Molecular Biology I, Center of Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, 45141 Essen, Germany
| | - Sandra Koska
- Molecular Biology I, Center of Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, 45141 Essen, Germany
| | - David Ron
- Cellular Pathophysiology and Clinical Biochemistry, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
| | - Hemmo Meyer
- Molecular Biology I, Center of Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, 45141 Essen, Germany
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2
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Wang J, Chistov G, Zhang J, Huntington B, Salem I, Sandholu A, Arold ST. P-NADs: PUX-based NAnobody degraders for ubiquitin-independent degradation of target proteins. Heliyon 2024; 10:e34487. [PMID: 39130484 PMCID: PMC11315185 DOI: 10.1016/j.heliyon.2024.e34487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Revised: 07/09/2024] [Accepted: 07/10/2024] [Indexed: 08/13/2024] Open
Abstract
Targeted protein degradation (TPD) allows cells to maintain a functional proteome and to rapidly adapt to changing conditions. Methods that repurpose TPD for the deactivation of specific proteins have demonstrated significant potential in therapeutic and research applications. Most of these methods are based on proteolysis targeting chimaeras (PROTACs) which link the protein target to an E3 ubiquitin ligase, resulting in the ubiquitin-based degradation of the target protein. In this study, we introduce a method for ubiquitin-independent TPD based on nanobody-conjugated plant ubiquitin regulatory X domain-containing (PUX) adaptor proteins. We show that the PUX-based NAnobody Degraders (P-NADs) can unfold a target protein through the Arabidopsis and human orthologues of the CDC48 unfoldase without the need for ubiquitination or initiating motifs. We demonstrate that P-NAD plasmids can be transfected into a human cell line, where the produced P-NADs use the endogenous CDC48 machinery for ubiquitin-independent TPD of a 143 kDa multidomain protein. Thus, P-NADs pave the road for ubiquitin-independent therapeutic TPD approaches. In addition, the modular P-NAD design combined with in vitro and cellular assays provide a versatile platform for elucidating functional aspects of CDC48-based TPD in plants and animals.
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Affiliation(s)
- Jun Wang
- Biological and Environmental Science and Engineering Division, Computational Biology Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | | | - Junrui Zhang
- Biological and Environmental Science and Engineering Division, Computational Biology Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Brandon Huntington
- Biological and Environmental Science and Engineering Division, Computational Biology Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Israa Salem
- Biological and Environmental Science and Engineering Division, Computational Biology Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Anandsukeerthi Sandholu
- Biological and Environmental Science and Engineering Division, Computational Biology Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Stefan T. Arold
- Biological and Environmental Science and Engineering Division, Computational Biology Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
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3
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Noireterre A, Stutz F. Cdc48/p97 segregase: Spotlight on DNA-protein crosslinks. DNA Repair (Amst) 2024; 139:103691. [PMID: 38744091 DOI: 10.1016/j.dnarep.2024.103691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 04/30/2024] [Accepted: 05/01/2024] [Indexed: 05/16/2024]
Abstract
The ATP-dependent molecular chaperone Cdc48 (in yeast) and its human counterpart p97 (also known as VCP), are essential for a variety of cellular processes, including the removal of DNA-protein crosslinks (DPCs) from the DNA. Growing evidence demonstrates in the last years that Cdc48/p97 is pivotal in targeting ubiquitinated and SUMOylated substrates on chromatin, thereby supporting the DNA damage response. Along with its cofactors, notably Ufd1-Npl4, Cdc48/p97 has emerged as a central player in the unfolding and processing of DPCs. This review introduces the detailed structure, mechanism and cellular functions of Cdc48/p97 with an emphasis on the current knowledge of DNA-protein crosslink repair pathways across several organisms. The review concludes by discussing the potential therapeutic relevance of targeting p97 in DPC repair.
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Affiliation(s)
- Audrey Noireterre
- Department of Molecular and Cellular Biology, University of Geneva, Geneva 4 1211, Switzerland
| | - Françoise Stutz
- Department of Molecular and Cellular Biology, University of Geneva, Geneva 4 1211, Switzerland.
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4
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Cao X, Lake M, Van der Hoeven G, Claes Z, Del Pino García J, Lemaire S, Greiner EC, Karamanou S, Van Eynde A, Kettenbach AN, Natera de Benito D, Carrera García L, Hernando Davalillo C, Ortez C, Nascimento A, Urreizti R, Bollen M. SDS22 coordinates the assembly of holoenzymes from nascent protein phosphatase-1. Nat Commun 2024; 15:5359. [PMID: 38918402 PMCID: PMC11199634 DOI: 10.1038/s41467-024-49746-4] [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: 11/24/2023] [Accepted: 06/18/2024] [Indexed: 06/27/2024] Open
Abstract
SDS22 forms an inactive complex with nascent protein phosphatase PP1 and Inhibitor-3. SDS22:PP1:Inhibitor-3 is a substrate for the ATPase p97/VCP, which liberates PP1 for binding to canonical regulatory subunits. The exact role of SDS22 in PP1-holoenzyme assembly remains elusive. Here, we show that SDS22 stabilizes nascent PP1. In the absence of SDS22, PP1 is gradually lost, resulting in substrate hyperphosphorylation and a proliferation arrest. Similarly, we identify a female individual with a severe neurodevelopmental disorder bearing an unstable SDS22 mutant, associated with decreased PP1 levels. We furthermore find that SDS22 directly binds to Inhibitor-3 and that this is essential for the stable assembly of SDS22:PP1: Inhibitor-3, the recruitment of p97/VCP, and the extraction of SDS22 during holoenzyme assembly. SDS22 with a disabled Inhibitor-3 binding site co-transfers with PP1 to canonical regulatory subunits, thereby forming non-functional holoenzymes. Our data show that SDS22, through simultaneous interaction with PP1 and Inhibitor-3, integrates the major steps of PP1 holoenzyme assembly.
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Affiliation(s)
- Xinyu Cao
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000, Leuven, Belgium
| | - Madryn Lake
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000, Leuven, Belgium
| | - Gerd Van der Hoeven
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000, Leuven, Belgium
| | - Zander Claes
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000, Leuven, Belgium
| | - Javier Del Pino García
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000, Leuven, Belgium
| | - Sarah Lemaire
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000, Leuven, Belgium
| | - Elora C Greiner
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
- Dartmouth Cancer Center, Lebanon, NH, USA
| | - Spyridoula Karamanou
- Laboratory of Molecular Bacteriology, KU Leuven Department of Microbiology and Immunology, University of Leuven, Leuven, Belgium
| | - Aleyde Van Eynde
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000, Leuven, Belgium
| | - Arminja N Kettenbach
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
- Dartmouth Cancer Center, Lebanon, NH, USA
| | | | - Laura Carrera García
- Neuromuscular Unit, Department of Neurology, Hospital Sant Joan de Deu, Barcelona, Spain
| | | | - Carlos Ortez
- Neuromuscular Unit, Department of Neurology, Hospital Sant Joan de Deu, Barcelona, Spain
| | - Andrés Nascimento
- Neuromuscular Unit, Department of Neurology, Hospital Sant Joan de Deu, Barcelona, Spain
| | - Roser Urreizti
- Clinical Biochemistry Department, Institut de Recerca Sant Joan de Deu, Hospital Sant Joan de Deu, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Mathieu Bollen
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000, Leuven, Belgium.
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5
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Sun X, Tang X, Qiu H. Cardiac-Specific Suppression of Valosin-Containing Protein Induces Progressive Heart Failure and Premature Mortality Correlating with Temporal Dysregulations in mTOR Complex 2 and Protein Phosphatase 1. Int J Mol Sci 2024; 25:6445. [PMID: 38928151 PMCID: PMC11203954 DOI: 10.3390/ijms25126445] [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: 05/14/2024] [Revised: 06/06/2024] [Accepted: 06/08/2024] [Indexed: 06/28/2024] Open
Abstract
Valosin-containing protein (VCP), an ATPase-associated protein, is emerging as a crucial regulator in cardiac pathologies. However, the pivotal role of VCP in the heart under physiological conditions remains undetermined. In this study, we tested a hypothesis that sufficient VCP expression is required for cardiac development and physiological cardiac function. Thus, we generated a cardiac-specific VCP knockout (KO) mouse model and assessed the consequences of VCP suppression on the heart through physiological and molecular studies at baseline. Our results reveal that homozygous KO mice are embryonically lethal, whereas heterozygous KO mice with a reduction in VCP by ~40% in the heart are viable at birth but progressively develop heart failure and succumb to mortality at the age of 10 to 12 months. The suppression of VCP induced a selective activation of the mammalian target of rapamycin complex 1 (mTORC1) but not mTORC2 at the early age of 12 weeks. The prolonged suppression of VCP increased the expression (by ~2 folds) and nuclear translocation (by >4 folds) of protein phosphatase 1 (PP1), a key mediator of protein dephosphorylation, accompanied by a remarked reduction (~80%) in AKTSer473 phosphorylation in VCP KO mouse hearts at a later age but not the early stage. These temporal molecular alterations were highly associated with the progressive decline in cardiac function. Overall, our findings shed light on the essential role of VCP in the heart under physiological conditions, providing new insights into molecular mechanisms in the development of heart failure.
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Affiliation(s)
- Xiaonan Sun
- Center for Molecular and Translational Medicine, Institute of Biomedical Science, Georgia State University, Atlanta, GA 30303, USA; (X.S.); (X.T.)
| | - Xicong Tang
- Center for Molecular and Translational Medicine, Institute of Biomedical Science, Georgia State University, Atlanta, GA 30303, USA; (X.S.); (X.T.)
- Cardiovascular Translational Research Center, Department of Internal Medicine, College of Medicine-Phoenix, University of Arizona, Phoenix, AZ 85004, USA
| | - Hongyu Qiu
- Center for Molecular and Translational Medicine, Institute of Biomedical Science, Georgia State University, Atlanta, GA 30303, USA; (X.S.); (X.T.)
- Cardiovascular Translational Research Center, Department of Internal Medicine, College of Medicine-Phoenix, University of Arizona, Phoenix, AZ 85004, USA
- Clinical Translational Sciences (CTS) and Bio5 Institution, University of Arizona, Tucson, AZ 85721, USA
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6
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Li H, Ji Z, Paulo JA, Gygi SP, Rapoport TA. Bidirectional substrate shuttling between the 26S proteasome and the Cdc48 ATPase promotes protein degradation. Mol Cell 2024; 84:1290-1303.e7. [PMID: 38401542 DOI: 10.1016/j.molcel.2024.01.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 12/12/2023] [Accepted: 01/31/2024] [Indexed: 02/26/2024]
Abstract
Most eukaryotic proteins are degraded by the 26S proteasome after modification with a polyubiquitin chain. Substrates lacking unstructured segments cannot be degraded directly and require prior unfolding by the Cdc48 ATPase (p97 or VCP in mammals) in complex with its ubiquitin-binding partner Ufd1-Npl4 (UN). Here, we use purified yeast components to reconstitute Cdc48-dependent degradation of well-folded model substrates by the proteasome. We show that a minimal system consists of the 26S proteasome, the Cdc48-UN ATPase complex, the proteasome cofactor Rad23, and the Cdc48 cofactors Ubx5 and Shp1. Rad23 and Ubx5 stimulate polyubiquitin binding to the 26S proteasome and the Cdc48-UN complex, respectively, allowing these machines to compete for substrates before and after their unfolding. Shp1 stimulates protein unfolding by the Cdc48-UN complex rather than substrate recruitment. Experiments in yeast cells confirm that many proteins undergo bidirectional substrate shuttling between the 26S proteasome and Cdc48 ATPase before being degraded.
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Affiliation(s)
- Hao Li
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Zhejian Ji
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Joao A Paulo
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Steven P Gygi
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Tom A Rapoport
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
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7
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Li H, Ji Z, Paulo JA, Gygi SP, Rapoport TA. Bidirectional substrate shuttling between the 26S proteasome and the Cdc48 ATPase promotes protein degradation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.20.572403. [PMID: 38187576 PMCID: PMC10769200 DOI: 10.1101/2023.12.20.572403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Most eukaryotic proteins are degraded by the 26S proteasome after modification with a polyubiquitin chain. Substrates lacking unstructured segments cannot be degraded directly and require prior unfolding by the Cdc48 ATPase (p97 or VCP in mammals) in complex with its ubiquitin-binding partner Ufd1-Npl4 (UN). Here, we use purified yeast components to reconstitute Cdc48-dependent degradation of well-folded model substrates by the proteasome. We show that a minimal system consists of the 26S proteasome, the Cdc48-UN ATPase complex, the proteasome cofactor Rad23, and the Cdc48 cofactors Ubx5 and Shp1. Rad23 and Ubx5 stimulate polyubiquitin binding to the 26S proteasome and the Cdc48-UN complex, respectively, allowing these machines to compete for substrates before and after their unfolding. Shp1 stimulates protein unfolding by the Cdc48-UN complex, rather than substrate recruitment. In vivo experiments confirm that many proteins undergo bidirectional substrate shuttling between the 26S proteasome and Cdc48 ATPase before being degraded.
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8
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Braxton JR, Altobelli CR, Tucker MR, Tse E, Thwin AC, Arkin MR, Southworth DR. The p97/VCP adaptor UBXD1 drives AAA+ remodeling and ring opening through multi-domain tethered interactions. Nat Struct Mol Biol 2023; 30:2009-2019. [PMID: 37945741 PMCID: PMC10716044 DOI: 10.1038/s41594-023-01126-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 09/14/2023] [Indexed: 11/12/2023]
Abstract
p97, also known as valosin-containing protein, is an essential cytosolic AAA+ (ATPases associated with diverse cellular activities) hexamer that unfolds substrate polypeptides to support protein homeostasis and macromolecular disassembly. Distinct sets of p97 adaptors guide cellular functions but their roles in direct control of the hexamer are unclear. The UBXD1 adaptor localizes with p97 in critical mitochondria and lysosome clearance pathways and contains multiple p97-interacting domains. Here we identify UBXD1 as a potent p97 ATPase inhibitor and report structures of intact human p97-UBXD1 complexes that reveal extensive UBXD1 contacts across p97 and an asymmetric remodeling of the hexamer. Conserved VIM, UBX and PUB domains tether adjacent protomers while a connecting strand forms an N-terminal domain lariat with a helix wedged at the interprotomer interface. An additional VIM-connecting helix binds along the second (D2) AAA+ domain. Together, these contacts split the hexamer into a ring-open conformation. Structures, mutagenesis and comparisons to other adaptors further reveal how adaptors containing conserved p97-remodeling motifs regulate p97 ATPase activity and structure.
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Affiliation(s)
- Julian R Braxton
- Graduate Program in Chemistry and Chemical Biology, University of California San Francisco, San Francisco, CA, USA
- Department of Biochemistry and Biophysics and Institute for Neurodegenerative Diseases, University of California San Francisco, San Francisco, CA, USA
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Chad R Altobelli
- Graduate Program in Chemistry and Chemical Biology, University of California San Francisco, San Francisco, CA, USA
- Department of Pharmaceutical Chemistry and Small Molecule Discovery Center, University of California San Francisco, San Francisco, CA, USA
| | - Maxwell R Tucker
- Department of Biochemistry and Biophysics and Institute for Neurodegenerative Diseases, University of California San Francisco, San Francisco, CA, USA
- Graduate Program in Biophysics, University of California San Francisco, San Francisco, CA, USA
| | - Eric Tse
- Department of Biochemistry and Biophysics and Institute for Neurodegenerative Diseases, University of California San Francisco, San Francisco, CA, USA
| | - Aye C Thwin
- Department of Biochemistry and Biophysics and Institute for Neurodegenerative Diseases, University of California San Francisco, San Francisco, CA, USA
| | - Michelle R Arkin
- Department of Pharmaceutical Chemistry and Small Molecule Discovery Center, University of California San Francisco, San Francisco, CA, USA.
| | - Daniel R Southworth
- Department of Biochemistry and Biophysics and Institute for Neurodegenerative Diseases, University of California San Francisco, San Francisco, CA, USA.
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9
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Braxton JR, Southworth DR. Structural insights of the p97/VCP AAA+ ATPase: How adapter interactions coordinate diverse cellular functionality. J Biol Chem 2023; 299:105182. [PMID: 37611827 PMCID: PMC10641518 DOI: 10.1016/j.jbc.2023.105182] [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: 05/30/2023] [Revised: 08/05/2023] [Accepted: 08/14/2023] [Indexed: 08/25/2023] Open
Abstract
p97/valosin-containing protein is an essential eukaryotic AAA+ ATPase with diverse functions including protein homeostasis, membrane remodeling, and chromatin regulation. Dysregulation of p97 function causes severe neurodegenerative disease and is associated with cancer, making this protein a significant therapeutic target. p97 extracts polypeptide substrates from macromolecular assemblies by hydrolysis-driven translocation through its central pore. Growing evidence indicates that this activity is highly coordinated by "adapter" partner proteins, of which more than 30 have been identified and are commonly described to facilitate translocation through substrate recruitment or modification. In so doing, these adapters enable critical p97-dependent functions such as extraction of misfolded proteins from the endoplasmic reticulum or mitochondria, and are likely the reason for the extreme functional diversity of p97 relative to other AAA+ translocases. Here, we review the known functions of adapter proteins and highlight recent structural and biochemical advances that have begun to reveal the diverse molecular bases for adapter-mediated regulation of p97 function. These studies suggest that the range of mechanisms by which p97 activity is controlled is vastly underexplored with significant advances possible for understanding p97 regulation by the most known adapters.
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Affiliation(s)
- Julian R Braxton
- Graduate Program in Chemistry and Chemical Biology, University of California, San Francisco, San Francisco, California, USA; Department of Biochemistry and Biophysics and Institute for Neurodegenerative Diseases, University of California, San Francisco, San Francisco, California, USA
| | - Daniel R Southworth
- Department of Biochemistry and Biophysics and Institute for Neurodegenerative Diseases, University of California, San Francisco, San Francisco, California, USA.
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10
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Braxton JR, Altobelli CR, Tucker MR, Tse E, Thwin AC, Arkin MR, Southworth DR. The p97/VCP adapter UBXD1 drives AAA+ remodeling and ring opening through multi-domain tethered interactions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.15.540864. [PMID: 37292947 PMCID: PMC10245715 DOI: 10.1101/2023.05.15.540864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
p97/VCP is an essential cytosolic AAA+ ATPase hexamer that extracts and unfolds substrate polypeptides during protein homeostasis and degradation. Distinct sets of p97 adapters guide cellular functions but their roles in direct control of the hexamer are unclear. The UBXD1 adapter localizes with p97 in critical mitochondria and lysosome clearance pathways and contains multiple p97-interacting domains. We identify UBXD1 as a potent p97 ATPase inhibitor and report structures of intact p97:UBXD1 complexes that reveal extensive UBXD1 contacts across p97 and an asymmetric remodeling of the hexamer. Conserved VIM, UBX, and PUB domains tether adjacent protomers while a connecting strand forms an N-terminal domain lariat with a helix wedged at the interprotomer interface. An additional VIM-connecting helix binds along the second AAA+ domain. Together these contacts split the hexamer into a ring-open conformation. Structures, mutagenesis, and comparisons to other adapters further reveal how adapters containing conserved p97-remodeling motifs regulate p97 ATPase activity and structure.
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Affiliation(s)
- Julian R. Braxton
- Graduate Program in Chemistry and Chemical Biology; University of California, San Francisco; San Francisco, CA 94158, USA
- Department of Biochemistry and Biophysics and Institute for Neurodegenerative Diseases; University of California, San Francisco; San Francisco, CA 94158, USA
| | - Chad R. Altobelli
- Graduate Program in Chemistry and Chemical Biology; University of California, San Francisco; San Francisco, CA 94158, USA
- Department of Pharmaceutical Chemistry and Small Molecule Discovery Center; University of California, San Francisco; San Francisco, CA 94158, USA
| | - Maxwell R. Tucker
- Department of Biochemistry and Biophysics and Institute for Neurodegenerative Diseases; University of California, San Francisco; San Francisco, CA 94158, USA
- Graduate Program in Biophysics; University of California, San Francisco; San Francisco, CA 94158, USA
| | - Eric Tse
- Department of Biochemistry and Biophysics and Institute for Neurodegenerative Diseases; University of California, San Francisco; San Francisco, CA 94158, USA
| | - Aye C. Thwin
- Department of Biochemistry and Biophysics and Institute for Neurodegenerative Diseases; University of California, San Francisco; San Francisco, CA 94158, USA
| | - Michelle R. Arkin
- Department of Pharmaceutical Chemistry and Small Molecule Discovery Center; University of California, San Francisco; San Francisco, CA 94158, USA
| | - Daniel R. Southworth
- Department of Biochemistry and Biophysics and Institute for Neurodegenerative Diseases; University of California, San Francisco; San Francisco, CA 94158, USA
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11
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Cooney I, Schubert HL, Cedeno K, Lin HJL, Price JC, Hill CP, Shen PS. Visualization of the Cdc48 AAA+ ATPase protein unfolding pathway. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.13.540638. [PMID: 38654823 PMCID: PMC11037871 DOI: 10.1101/2023.05.13.540638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
The Cdc48 AAA+ ATPase is an abundant and essential enzyme that unfolds substrates in multiple protein quality control pathways. The enzyme includes two conserved AAA+ ATPase cassettes, D1 and D2, that assemble as hexameric rings with D1 stacked above D2. Here, we report an ensemble of structures of Cdc48 affinity purified from lysate in complex with the adaptor Shp1 in the act of unfolding substrate. Our analysis reveals a continuum of structural snapshots that spans the entire translocation cycle. These data reveal new elements of Shp1-Cdc48 binding and support a "hand-over-hand" mechanism in which the sequential movement of individual subunits is closely coordinated. D1 hydrolyzes ATP and disengages from substrate prior to D2, while D2 rebinds ATP and re-engages with substrate prior to D1, thereby explaining the dominant role played by D2 in substrate translocation/unfolding.
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Affiliation(s)
- Ian Cooney
- Department of Biochemistry, 15 N. Medical Drive East, University of Utah, Salt Lake City, UT, 84112, USA
| | - Heidi L. Schubert
- Department of Biochemistry, 15 N. Medical Drive East, University of Utah, Salt Lake City, UT, 84112, USA
| | - Karina Cedeno
- Department of Biochemistry, 15 N. Medical Drive East, University of Utah, Salt Lake City, UT, 84112, USA
| | - Hsien-Jung L. Lin
- Department of Chemistry and Biochemistry, C100 BNSN, Brigham Young University, Provo, UT, 84602, USA
| | - John C Price
- Department of Chemistry and Biochemistry, C100 BNSN, Brigham Young University, Provo, UT, 84602, USA
| | - Christopher P Hill
- Department of Biochemistry, 15 N. Medical Drive East, University of Utah, Salt Lake City, UT, 84112, USA
| | - Peter S Shen
- Department of Biochemistry, 15 N. Medical Drive East, University of Utah, Salt Lake City, UT, 84112, USA
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12
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Meyer H, van den Boom J. Targeting of client proteins to the VCP/p97/Cdc48 unfolding machine. Front Mol Biosci 2023; 10:1142989. [PMID: 36825201 PMCID: PMC9941556 DOI: 10.3389/fmolb.2023.1142989] [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: 01/12/2023] [Accepted: 01/30/2023] [Indexed: 02/10/2023] Open
Abstract
The AAA+ ATPase p97 (also called VCP or Cdc48) is a major protein unfolding machine with hundreds of clients in diverse cellular pathways that are critical for cell homeostasis, proliferation and signaling. In this review, we summarize recent advances in understanding how diverse client proteins are targeted to the p97 machine to facilitate client degradation or to strip clients from binding partners for regulation. We describe an elaborate system that is governed by at least two types of alternative adapters. The Ufd1-Npl4 adapter along with accessory adapters targets ubiquitylated clients in the majority of pathways and uses ubiquitin as a universal unfolding tag. In contrast, the family of SEP-domain adapters such as p37 can target clients directly to p97 in a ubiquitin-independent manner. Despite the different targeting strategies, both pathways converge by inserting the client into the p97 pore to initiate a peptide threading mechanism through the central channel of p97 that drives client protein unfolding, protein extraction from membranes and protein complex disassembly processes.
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Affiliation(s)
| | - Johannes van den Boom
- Center of Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
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Ahlstedt BA, Ganji R, Raman M. The functional importance of VCP to maintaining cellular protein homeostasis. Biochem Soc Trans 2022; 50:1457-1469. [PMID: 36196920 PMCID: PMC9704522 DOI: 10.1042/bst20220648] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 09/09/2022] [Accepted: 09/15/2022] [Indexed: 11/17/2022]
Abstract
The AAA-ATPase (ATPases associated with diverse cellular activities) valosin-containing protein (VCP), is essential for many cellular pathways including but not limited to endoplasmic reticulum-associated degradation (ERAD), DNA damage responses, and cell cycle regulation. VCP primarily identifies ubiquitylated proteins in these pathways and mediates their unfolding and degradation by the 26S proteasome. This review summarizes recent research on VCP that has uncovered surprising new ways that this ATPase is regulated, new aspects of recognition of substrates and novel pathways and substrates that utilize its activity.
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Affiliation(s)
- Brittany A. Ahlstedt
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA, U.S.A
| | - Rakesh Ganji
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA, U.S.A
| | - Malavika Raman
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA, U.S.A
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14
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Fujisawa R, Polo Rivera C, Labib KPM. Multiple UBX proteins reduce the ubiquitin threshold of the mammalian p97-UFD1-NPL4 unfoldase. eLife 2022; 11:e76763. [PMID: 35920641 PMCID: PMC9377798 DOI: 10.7554/elife.76763] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 08/02/2022] [Indexed: 11/17/2022] Open
Abstract
The p97/Cdc48 ATPase and its ubiquitin receptors Ufd1-Npl4 are essential to unfold ubiquitylated proteins in many areas of eukaryotic cell biology. In yeast, Cdc48-Ufd1-Npl4 is controlled by a quality control mechanism, whereby substrates must be conjugated to at least five ubiquitins. Here, we show that mammalian p97-UFD1-NPL4 is governed by a complex interplay between additional p97 cofactors and the number of conjugated ubiquitins. Using reconstituted assays for the disassembly of ubiquitylated CMG (Cdc45-MCM-GINS) helicase by human p97-UFD1-NPL4, we show that the unfoldase has a high ubiquitin threshold for substrate unfolding, which can be reduced by the UBX proteins UBXN7, FAF1, or FAF2. Our data indicate that the UBX proteins function by binding to p97-UFD1-NPL4 and stabilising productive interactions between UFD1-NPL4 and K48-linked chains of at least five ubiquitins. Stimulation by UBXN7 is dependent upon known ubiquitin-binding motifs, whereas FAF1 and FAF2 use a previously uncharacterised coiled-coil domain to reduce the ubiquitin threshold of p97-UFD1-NPL4. We show that deleting the Ubnx7 and Faf1 genes impairs CMG disassembly during S-phase and mitosis and sensitises cells to reduced ubiquitin ligase activity. These findings indicate that multiple UBX proteins are important for the efficient unfolding of ubiquitylated proteins by p97-UFD1-NPL4 in mammalian cells.
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Affiliation(s)
- Ryo Fujisawa
- The MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of DundeeDundeeUnited Kingdom
| | - Cristian Polo Rivera
- The MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of DundeeDundeeUnited Kingdom
| | - Karim PM Labib
- The MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of DundeeDundeeUnited Kingdom
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15
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Kröning A, van den Boom J, Kracht M, Kueck AF, Meyer H. Ubiquitin-directed AAA+ ATPase p97/VCP unfolds stable proteins crosslinked to DNA for proteolysis by SPRTN. J Biol Chem 2022; 298:101976. [PMID: 35469923 PMCID: PMC9127365 DOI: 10.1016/j.jbc.2022.101976] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 04/13/2022] [Accepted: 04/18/2022] [Indexed: 12/02/2022] Open
Abstract
The protease SPRTN degrades DNA-protein crosslinks (DPCs) that threaten genome stability. SPRTN has been connected to the ubiquitin-directed protein unfoldase p97 (also called VCP or Cdc48), but a functional cooperation has not been demonstrated directly. Here, we biochemically reconstituted p97-assisted proteolysis with purified proteins and showed that p97 targets ubiquitin-modified DPCs and unfolds them to prepare them for proteolysis by SPRTN. We demonstrate that purified SPRTN alone was unable to degrade a tightly-folded Eos fluorescent reporter protein even when Eos was crosslinked to DNA (Eos-DPC). However, when present, p97 unfolded poly-ubiquitinated Eos-DPC in a manner requiring its ubiquitin adapter, Ufd1-Npl4. Notably, we show that, in cooperation with p97 and Ufd1-Npl4, SPRTN proteolyzed unfolded Eos-DPC, which relied on recognition of the DNA-crosslink by SPRTN. In a simplified unfolding assay, we further demonstrate that p97, while unfolding a protein substrate, can surmount the obstacle of a DNA crosslink site in the substrate. Thus, our data demonstrate that p97, in conjunction with Ufd1-Npl4, assists SPRTN-mediated proteolysis of tightly-folded proteins crosslinked to DNA, even threading bulky protein-DNA adducts. These findings will be relevant for understanding how cells handle DPCs to ensure genome stability and for designing strategies that target p97 in combination cancer therapy.
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Affiliation(s)
- Alexander Kröning
- Center of Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - Johannes van den Boom
- Center of Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - Matthias Kracht
- Center of Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - Anja F Kueck
- Center of Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - Hemmo Meyer
- Center of Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany.
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Lin J, Shorter J, Lucius AL. AAA+ proteins: one motor, multiple ways to work. Biochem Soc Trans 2022; 50:895-906. [PMID: 35356966 PMCID: PMC9115847 DOI: 10.1042/bst20200350] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 03/14/2022] [Accepted: 03/15/2022] [Indexed: 12/15/2022]
Abstract
Numerous ATPases associated with diverse cellular activities (AAA+) proteins form hexameric, ring-shaped complexes that function via ATPase-coupled translocation of substrates across the central channel. Cryo-electron microscopy of AAA+ proteins processing substrate has revealed non-symmetric, staircase-like hexameric structures that indicate a sequential clockwise/2-residue step translocation model for these motors. However, for many of the AAA+ proteins that share similar structural features, their translocation properties have not yet been experimentally determined. In the cases where translocation mechanisms have been determined, a two-residue translocation step-size has not been resolved. In this review, we explore Hsp104, ClpB, ClpA and ClpX as examples to review the experimental methods that have been used to examine, in solution, the translocation mechanisms employed by AAA+ motor proteins. We then ask whether AAA+ motors sharing similar structural features can have different translocation mechanisms. Finally, we discuss whether a single AAA+ motor can adopt multiple translocation mechanisms that are responsive to different challenges imposed by the substrate or the environment. We suggest that AAA+ motors adopt more than one translocation mechanism and are tuned to switch to the most energetically efficient mechanism when constraints are applied.
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Affiliation(s)
- JiaBei Lin
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, U.S.A
| | - James Shorter
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, U.S.A
| | - Aaron L. Lucius
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, AL, U.S.A
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Unfolding by Cdc48/p97: different strokes for different folks. Trends Cell Biol 2022; 32:278-280. [DOI: 10.1016/j.tcb.2022.01.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 01/10/2022] [Indexed: 01/02/2023]
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