1
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Gill JK, Shaw GS. Using Förster Resonance Energy Transfer (FRET) to Understand the Ubiquitination Landscape. Chembiochem 2024:e202400193. [PMID: 38632088 DOI: 10.1002/cbic.202400193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 04/15/2024] [Accepted: 04/17/2024] [Indexed: 04/19/2024]
Abstract
Förster resonance energy transfer (FRET) is a fluorescence technique that allows quantitative measurement of protein interactions, kinetics and dynamics. This review covers the use of FRET to study the structures and mechanisms of ubiquitination and related proteins. We survey FRET assays that have been developed where donor and acceptor fluorophores are placed on E1, E2 or E3 enzymes and ubiquitin (Ub) to monitor steady-state and real-time transfer of Ub through the ubiquitination cascade. Specialized FRET probes placed on Ub and Ub-like proteins have been developed to monitor Ub removal by deubiquitinating enzymes (DUBs) that result in a loss of a FRET signal upon cleavage of the FRET probes. FRET has also been used to understand conformational changes in large complexes such as multimeric E3 ligases and the proteasome, frequently using sophisticated single molecule methods. Overall, FRET is a powerful tool to help unravel the intricacies of the complex ubiquitination system.
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Affiliation(s)
- Jashanjot Kaur Gill
- Department of Biochemistry, University of Western Ontario, London, Ontario, Canada, N6A5C1
| | - Gary S Shaw
- Department of Biochemistry, University of Western Ontario, London, Ontario, Canada, N6A5C1
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2
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Martinez-Corral R, Nam KM, DePace AH, Gunawardena J. The Hill function is the universal Hopfield barrier for sharpness of input-output responses. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.27.587054. [PMID: 38585761 PMCID: PMC10996692 DOI: 10.1101/2024.03.27.587054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
The Hill functions, ℋ h ( x ) = x h / 1 + x h , have been widely used in biology for over a century but, with the exception of ℋ 1 , they have had no justification other than as a convenient fit to empirical data. Here, we show that they are the universal limit for the sharpness of any input-output response arising from a Markov process model at thermodynamic equilibrium. Models may represent arbitrary molecular complexity, with multiple ligands, internal states, conformations, co-regulators, etc, under core assumptions that are detailed in the paper. The model output may be any linear combination of steady-state probabilities, with components other than the chosen input ligand held constant. This formulation generalises most of the responses in the literature. We use a coarse-graining method in the graph-theoretic linear framework to show that two sharpness measures for input-output responses fall within an effectively bounded region of the positive quadrant, Ω m ⊂ ℝ + 2 , for any equilibrium model with m input binding sites. Ω m exhibits a cusp which approaches, but never exceeds, the sharpness of ℋ m but the region and the cusp can be exceeded when models are taken away from thermodynamic equilibrium. Such fundamental thermodynamic limits are called Hopfield barriers and our results provide a biophysical justification for the Hill functions as the universal Hopfield barriers for sharpness. Our results also introduce an object, Ω m , whose structure may be of mathematical interest, and suggest the importance of characterising Hopfield barriers for other forms of cellular information processing.
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Affiliation(s)
| | - Kee-Myoung Nam
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Angela H. DePace
- Howard Hughes Medical Institute, Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Jeremy Gunawardena
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
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3
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Fang R, Lu Y. Simulating the conformational dynamics of the ATPase complex on proteasome using its free-energy landscape. STAR Protoc 2023; 4:102182. [PMID: 37768828 PMCID: PMC10542641 DOI: 10.1016/j.xpro.2023.102182] [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: 10/31/2022] [Revised: 01/16/2023] [Accepted: 02/23/2023] [Indexed: 09/30/2023] Open
Abstract
The AAA+ ATPase complex on proteasome powers its functions through a series of intricate conformational transitions. Here, we describe a procedure to simulate the conformational dynamics of the proteasomal ATPase complex. We first empirically determined the free-energy landscape (FEL) of proteasome and then simulated proteasome's conformational changes as stochastic transitions on its FEL. We compared the FEL-predicted proteasomal behaviors with experimental measurements and analyzed the map of the ATPase's global dynamics to gain mechanistic insights into proteasomal degradation. For complete details on the use and execution of this protocol, please refer to Fang et al. (2022).1.
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Affiliation(s)
- Rui Fang
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA; Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
| | - Ying Lu
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA.
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4
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Abstract
A survey of protein databases indicates that the majority of enzymes exist in oligomeric forms, with about half of those found in the UniProt database being homodimeric. Understanding why many enzymes are in their dimeric form is imperative. Recent developments in experimental and computational techniques have allowed for a deeper comprehension of the cooperative interactions between the subunits of dimeric enzymes. This review aims to succinctly summarize these recent advancements by providing an overview of experimental and theoretical methods, as well as an understanding of cooperativity in substrate binding and the molecular mechanisms of cooperative catalysis within homodimeric enzymes. Focus is set upon the beneficial effects of dimerization and cooperative catalysis. These advancements not only provide essential case studies and theoretical support for comprehending dimeric enzyme catalysis but also serve as a foundation for designing highly efficient catalysts, such as dimeric organic catalysts. Moreover, these developments have significant implications for drug design, as exemplified by Paxlovid, which was designed for the homodimeric main protease of SARS-CoV-2.
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Affiliation(s)
- Ke-Wei Chen
- Lab of Computional Chemistry and Drug Design, State Key Laboratory of Chemical Oncogenomics, Peking University Shenzhen Graduate School, Shenzhen 518055, China
| | - Tian-Yu Sun
- Shenzhen Bay Laboratory, Shenzhen 518132, China
| | - Yun-Dong Wu
- Lab of Computional Chemistry and Drug Design, State Key Laboratory of Chemical Oncogenomics, Peking University Shenzhen Graduate School, Shenzhen 518055, China
- Shenzhen Bay Laboratory, Shenzhen 518132, China
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5
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Warnock JL, Jobin GW, Kumar S, Tomko RJ. Assembly chaperone Nas6 selectively destabilizes 26S proteasomes with defective regulatory particle-core particle interfaces. J Biol Chem 2023; 299:102894. [PMID: 36634850 PMCID: PMC9943895 DOI: 10.1016/j.jbc.2023.102894] [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: 10/17/2022] [Revised: 12/22/2022] [Accepted: 12/28/2022] [Indexed: 01/11/2023] Open
Abstract
The 26S proteasome is a 66-subunit-chambered protease present in all eukaryotes that maintains organismal health by degrading unneeded or defective proteins. Defects in proteasome function or assembly are known to contribute to the development of various cancers, neurodegeneration, and diabetes. During proteasome biogenesis, a family of evolutionarily conserved chaperones assembles a hexameric ring of AAA+ family ATPase subunits contained within the proteasomal regulatory particle (RP) and guide their docking onto the surface of the proteolytic core particle (CP). This RP-CP interaction couples the substrate capture and unfolding process to proteolysis. We previously reported a mutation in the proteasome that promoted dissociation of the RP and CP by one of these chaperones, Nas6. However, the nature of the signal for Nas6-dependent proteasome disassembly and the generality of this postassembly proteasome quality control function for Nas6 remain unknown. Here, we use structure-guided mutagenesis and in vitro proteasome disassembly assays to demonstrate that Nas6 more broadly destabilizes 26S proteasomes with a defective RP-CP interface. We show that Nas6 can promote dissociation of mature proteasomes into RP and CP in cells harboring defects on either side of the RP-CP interface. This function is unique to Nas6 and independent from other known RP assembly chaperones. Further biochemical experiments suggest that Nas6 may exploit a weakened RP-CP interface to dissociate the RP from the CP. We propose that this postassembly role of Nas6 may fulfill a quality control function in cells by promoting the recycling of functional subcomplexes contained within defective proteasomes.
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6
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Hogrel G, Marino-Puertas L, Laurent S, Ibrahim Z, Covès J, Girard E, Gabel F, Fenel D, Daugeron MC, Clouet-d'Orval B, Basta T, Flament D, Franzetti B. Characterization of a small tRNA-binding protein that interacts with the archaeal proteasome complex. Mol Microbiol 2022; 118:16-29. [PMID: 35615908 PMCID: PMC9540759 DOI: 10.1111/mmi.14948] [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: 11/30/2020] [Revised: 05/15/2022] [Accepted: 05/17/2022] [Indexed: 11/27/2022]
Abstract
The proteasome system allows the elimination of functional or structurally impaired proteins. This includes the degradation of nascent peptides. In Archaea, how the proteasome complex interacts with the translational machinery remains to be described. Here, we characterised a small orphan protein, Q9UZY3 (Uniprot ID) conserved in Thermococcales. The protein was identified in native pull-down experiments using the proteasome regulatory complex (PAN) as bait. X-ray crystallography and SAXS experiments revealed that the protein is monomeric and adopts a β-barrel core structure with an Oligonucleotide/oligosaccharide-Binding (OB) fold, typically found in translation elongation factors. Mobility shift experiment showed that Q9UZY3 displays tRNA binding properties. Pull-downs, co-immunoprecipitation and ITC studies revealed that Q9UZY3 interacts in vitro with PAN. Native pull-downs and proteomic analysis using different versions of Q9UZY3 showed that the protein interacts with the assembled PAN-20S proteasome machinery in Pyrococcus abyssi cellular extracts. The protein was therefore named Pbp11, for Proteasome Binding Protein of 11 kDa. Interestingly, the interaction network of Pbp11 also includes ribosomal proteins, tRNA processing enzymes and exosome subunits dependent on Pbp11's N-terminal domain that was found to be essential for tRNA binding. Together these data suggest that Pbp11 participates in an interface between the proteasome and the translational machinery.
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Affiliation(s)
- Gaëlle Hogrel
- Univ Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France.,University of St Andrews, St Andrews, UK
| | | | - Sébastien Laurent
- Univ Brest, Ifremer, CNRS, Laboratoire de Microbiologie des Environnements Extrêmes, Plouzané, France
| | - Ziad Ibrahim
- Univ Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France.,University of Leicester, Leicester, UK
| | - Jacques Covès
- Univ Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France
| | - Eric Girard
- Univ Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France
| | - Frank Gabel
- Univ Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France
| | - Daphna Fenel
- Univ Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France
| | - Marie-Claire Daugeron
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Béatrice Clouet-d'Orval
- Laboratoire de Microbiologie et de Génétique Moléculaires, UMR5100, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, Université Paul Sabatier, Toulouse, France
| | - Tamara Basta
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Didier Flament
- Univ Brest, Ifremer, CNRS, Laboratoire de Microbiologie des Environnements Extrêmes, Plouzané, France
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7
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AAA+ proteins: one motor, multiple ways to work. Biochem Soc Trans 2022; 50:895-906. [PMID: 35356966 DOI: 10.1042/bst20200350] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [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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8
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Fang R, Hon J, Zhou M, Lu Y. An empirical energy landscape reveals mechanism of proteasome in polypeptide translocation. eLife 2022; 11:71911. [PMID: 35050852 PMCID: PMC8853663 DOI: 10.7554/elife.71911] [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: 07/03/2021] [Accepted: 01/17/2022] [Indexed: 11/15/2022] Open
Abstract
The ring-like ATPase complexes in the AAA+ family perform diverse cellular functions that require coordination between the conformational transitions of their individual ATPase subunits (Erzberger and Berger, 2006; Puchades et al., 2020). How the energy from ATP hydrolysis is captured to perform mechanical work by these coordinated movements is unknown. In this study, we developed a novel approach for delineating the nucleotide-dependent free-energy landscape (FEL) of the proteasome’s heterohexameric ATPase complex based on complementary structural and kinetic measurements. We used the FEL to simulate the dynamics of the proteasome and quantitatively evaluated the predicted structural and kinetic properties. The FEL model predictions are consistent with a wide range of experimental observations in this and previous studies and suggested novel mechanistic features of the proteasomal ATPases. We find that the cooperative movements of the ATPase subunits result from the design of the ATPase hexamer entailing a unique free-energy minimum for each nucleotide-binding status. ATP hydrolysis dictates the direction of substrate translocation by triggering an energy-dissipating conformational transition of the ATPase complex. In cells, many biological processes are carried out by large complexes made up of different proteins. These macromolecules act like miniature machines, flexing and moving their various parts to perform their cellular roles. One such complex is the 26S proteasome, which is responsible for recycling other proteins in the cell. The proteasome consists of approximately 31 subunits, including a ring of six ATPase enzymes that provide the complex with the energy it needs to mechanically unfold proteins. To understand how the proteasome and other large complexes work, researchers need to be able to monitor how their structure changes over time. These dynamics are challenging to probe directly with experiments, but can be assessed using computer simulations which track the movement of individual molecules and atoms. However, currently available computer systems do not have enough power to simulate the dynamics of large protein assemblies, like the 26S proteasome: for example, it would take longer than a thousand years to model how each atom in the complex moves over a timescale in which a biological change would happen (roughly 100ms). Here, Fang, Hon et al. have developed a new approach to simulate the structural dynamics of the proteasome’s ring of ATPase enzymes. Different known structures of the proteasome were used to identify the range of possible movements and shapes the complex can make. Fang, Hon et al. then used this data to calculate the energy level of each structure – also known as the ‘free energy landscape’ – and the rate of transition between them. This made it possible to simulate how the different ATPase enzymes move within the ring under a wide range of conditions. The simulated ATPase movements predicted how the proteasome machine would behave during various tasks, including degrading other proteins. Fan, Hon et al. carefully examined these predictions and found that they were consistent with experimental observations, validating their new simulation method. This work demonstrates the feasibility of simulating the actions of a large protein complex based on its free energy landscape. The results offer important insights into the functional mechanics of the 26S proteasome and related protein machines. Further work may help to simplify this process so the approach can be used to investigate the dynamics of other protein assemblies.
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Affiliation(s)
- Rui Fang
- Department of Systems Biology, Harvard Medical School, Boston, United States
| | - Jason Hon
- Department of Systems Biology, Harvard Medical School, Boston, United States
| | - Mengying Zhou
- Department of Systems Biology, Harvard Medical School, Boston, United States
| | - Ying Lu
- Department of Systems Biology, Harvard Medical School, Boston, United States
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9
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Khan YA, White KI, Brunger AT. The AAA+ superfamily: a review of the structural and mechanistic principles of these molecular machines. Crit Rev Biochem Mol Biol 2021; 57:156-187. [PMID: 34632886 DOI: 10.1080/10409238.2021.1979460] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
ATPases associated with diverse cellular activities (AAA+ proteins) are a superfamily of proteins found throughout all domains of life. The hallmark of this family is a conserved AAA+ domain responsible for a diverse range of cellular activities. Typically, AAA+ proteins transduce chemical energy from the hydrolysis of ATP into mechanical energy through conformational change, which can drive a variety of biological processes. AAA+ proteins operate in a variety of cellular contexts with diverse functions including disassembly of SNARE proteins, protein quality control, DNA replication, ribosome assembly, and viral replication. This breadth of function illustrates both the importance of AAA+ proteins in health and disease and emphasizes the importance of understanding conserved mechanisms of chemo-mechanical energy transduction. This review is divided into three major portions. First, the core AAA+ fold is presented. Next, the seven different clades of AAA+ proteins and structural details and reclassification pertaining to proteins in each clade are described. Finally, two well-known AAA+ proteins, NSF and its close relative p97, are reviewed in detail.
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Affiliation(s)
- Yousuf A Khan
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA.,Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA.,Department of Structural Biology, Stanford University, Stanford, CA, USA.,Department of Photon Science, Stanford University, Stanford, CA, USA.,Center for Biomedical Informatics Research, Stanford University, Stanford, CA, USA
| | - K Ian White
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA.,Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA.,Department of Structural Biology, Stanford University, Stanford, CA, USA.,Department of Photon Science, Stanford University, Stanford, CA, USA.,Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Axel T Brunger
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA.,Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA.,Department of Structural Biology, Stanford University, Stanford, CA, USA.,Department of Photon Science, Stanford University, Stanford, CA, USA.,Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
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10
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Kotamarthi HC, Sauer RT, Baker TA. The Non-dominant AAA+ Ring in the ClpAP Protease Functions as an Anti-stalling Motor to Accelerate Protein Unfolding and Translocation. Cell Rep 2021; 30:2644-2654.e3. [PMID: 32101742 DOI: 10.1016/j.celrep.2020.01.110] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 11/25/2019] [Accepted: 01/30/2020] [Indexed: 10/24/2022] Open
Abstract
ATP-powered unfoldases containing D1 and D2 AAA+ rings play important roles in protein homeostasis, but uncertainty about the function of each ring remains. Here we use single-molecule optical tweezers to assay mechanical unfolding and translocation by a variant of the ClpAP protease containing an ATPase-inactive D1 ring. This variant displays substantial mechanical defects in both unfolding and translocation of protein substrates. Notably, when D1 is hydrolytically inactive, ClpAP often stalls for times as long as minutes, and the substrate can back-slip through the enzyme when ATP concentrations are low. The inactive D1 variant also has more difficulty traveling in the N-to-C direction on a polypeptide track than it does moving in a C-to-N direction. These results indicate that D1 normally functions as an auxiliary/regulatory motor to promote uninterrupted enzyme advancement that is fueled largely by the D2 ring.
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Affiliation(s)
- Hema Chandra Kotamarthi
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA; Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Robert T Sauer
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Tania A Baker
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA; Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, USA.
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11
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Abstract
The 26S proteasome is the most complex ATP-dependent protease machinery, of ~2.5 MDa mass, ubiquitously found in all eukaryotes. It selectively degrades ubiquitin-conjugated proteins and plays fundamentally indispensable roles in regulating almost all major aspects of cellular activities. To serve as the sole terminal "processor" for myriad ubiquitylation pathways, the proteasome evolved exceptional adaptability in dynamically organizing a large network of proteins, including ubiquitin receptors, shuttle factors, deubiquitinases, AAA-ATPase unfoldases, and ubiquitin ligases, to enable substrate selectivity and processing efficiency and to achieve regulation precision of a vast diversity of substrates. The inner working of the 26S proteasome is among the most sophisticated, enigmatic mechanisms of enzyme machinery in eukaryotic cells. Recent breakthroughs in three-dimensional atomic-level visualization of the 26S proteasome dynamics during polyubiquitylated substrate degradation elucidated an extensively detailed picture of its functional mechanisms, owing to progressive methodological advances associated with cryogenic electron microscopy (cryo-EM). Multiple sites of ubiquitin binding in the proteasome revealed a canonical mode of ubiquitin-dependent substrate engagement. The proteasome conformation in the act of substrate deubiquitylation provided insights into how the deubiquitylating activity of RPN11 is enhanced in the holoenzyme and is coupled to substrate translocation. Intriguingly, three principal modes of coordinated ATP hydrolysis in the heterohexameric AAA-ATPase motor were discovered to regulate intermediate functional steps of the proteasome, including ubiquitin-substrate engagement, deubiquitylation, initiation of substrate translocation and processive substrate degradation. The atomic dissection of the innermost working of the 26S proteasome opens up a new era in our understanding of the ubiquitin-proteasome system and has far-reaching implications in health and disease.
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Affiliation(s)
- Youdong Mao
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, 02215, Massachusetts, USA. .,School of Physics, Center for Quantitative Biology, Peking University, Beijing, 100871, China.
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12
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Yu Y, Liu H, Yu Z, Witkowska HE, Cheng Y. Stoichiometry of Nucleotide Binding to Proteasome AAA+ ATPase Hexamer Established by Native Mass Spectrometry. Mol Cell Proteomics 2020; 19:1997-2015. [PMID: 32883800 PMCID: PMC7710143 DOI: 10.1074/mcp.ra120.002067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 08/04/2020] [Indexed: 11/06/2022] Open
Abstract
AAA+ ATPases constitute a large family of proteins that are involved in a plethora of cellular processes including DNA disassembly, protein degradation and protein complex disassembly. They typically form a hexametric ring-shaped structure with six subunits in a (pseudo) 6-fold symmetry. In a subset of AAA+ ATPases that facilitate protein unfolding and degradation, six subunits cooperate to translocate protein substrates through a central pore in the ring. The number and type of nucleotides in an AAA+ ATPase hexamer is inherently linked to the mechanism that underlies cooperation among subunits and couples ATP hydrolysis with substrate translocation. We conducted a native MS study of a monodispersed form of PAN, an archaeal proteasome AAA+ ATPase, to determine the number of nucleotides bound to each hexamer of the WT protein. We utilized ADP and its analogs (TNP-ADP and mant-ADP), and a nonhydrolyzable ATP analog (AMP-PNP) to study nucleotide site occupancy within the PAN hexamer in ADP- and ATP-binding states, respectively. Throughout all experiments we used a Walker A mutant (PANK217A) that is impaired in nucleotide binding as an internal standard to mitigate the effects of residual solvation on mass measurement accuracy and to serve as a reference protein to control for nonspecific nucleotide binding. This approach led to the unambiguous finding that a WT PAN hexamer carried - from expression host - six tightly bound ADP molecules that could be exchanged for ADP and ATP analogs. Although the Walker A mutant did not bind ADP analogs, it did bind AMP-PNP, albeit at multiple stoichiometries. We observed variable levels of hexamer dissociation and an appearance of multimeric species with the over-charged molecular ion distributions across repeated experiments. We posit that these phenomena originated during ESI process at the final stages of ESI droplet evolution.
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Affiliation(s)
- Yadong Yu
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, USA
| | - Haichuan Liu
- Department of OBGYN & Reproductive Sci, Sandler-Moore MS Core Facility, University of California San Francisco, San Francisco, California, USA
| | - Zanlin Yu
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, USA
| | - H Ewa Witkowska
- Department of OBGYN & Reproductive Sci, Sandler-Moore MS Core Facility, University of California San Francisco, San Francisco, California, USA.
| | - Yifan Cheng
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, USA; Howard Hughes Medical Institute, University of California San Francisco, San Francisco, California, USA.
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13
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Li Y, Wen L, Qu Y, Lv Y. Metal–Enzyme Hybrid Microspheres Assembled via Mg 2+-Allosteric Effector. Ind Eng Chem Res 2020. [DOI: 10.1021/acs.iecr.0c04721] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yuan Li
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
| | - Liyin Wen
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
- Institute for Medical Device Standard Administration, National Institutes for Food and Drug Control, Beijing 100050, China
| | - Yun Qu
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
| | - Yongqin Lv
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
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14
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Majumder P, Baumeister W. Proteasomes: unfoldase-assisted protein degradation machines. Biol Chem 2020; 401:183-199. [PMID: 31665105 DOI: 10.1515/hsz-2019-0344] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 10/02/2019] [Indexed: 01/05/2023]
Abstract
Proteasomes are the principal molecular machines for the regulated degradation of intracellular proteins. These self-compartmentalized macromolecular assemblies selectively degrade misfolded, mistranslated, damaged or otherwise unwanted proteins, and play a pivotal role in the maintenance of cellular proteostasis, in stress response, and numerous other processes of vital importance. Whereas the molecular architecture of the proteasome core particle (CP) is universally conserved, the unfoldase modules vary in overall structure, subunit complexity, and regulatory principles. Proteasomal unfoldases are AAA+ ATPases (ATPases associated with a variety of cellular activities) that unfold protein substrates, and translocate them into the CP for degradation. In this review, we summarize the current state of knowledge about proteasome - unfoldase systems in bacteria, archaea, and eukaryotes, the three domains of life.
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Affiliation(s)
- Parijat Majumder
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany
| | - Wolfgang Baumeister
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany
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15
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Mahieu E, Covès J, Krüger G, Martel A, Moulin M, Carl N, Härtlein M, Carlomagno T, Franzetti B, Gabel F. Observing Protein Degradation by the PAN-20S Proteasome by Time-Resolved Neutron Scattering. Biophys J 2020; 119:375-388. [PMID: 32640186 PMCID: PMC7376118 DOI: 10.1016/j.bpj.2020.06.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 06/05/2020] [Accepted: 06/09/2020] [Indexed: 12/21/2022] Open
Abstract
The proteasome is a key player of regulated protein degradation in all kingdoms of life. Although recent atomic structures have provided snapshots on a number of conformations, data on substrate states and populations during the active degradation process in solution remain scarce. Here, we use time-resolved small-angle neutron scattering of a deuterium-labeled GFPssrA substrate and an unlabeled archaeal PAN-20S system to obtain direct structural information on substrate states during ATP-driven unfolding and subsequent proteolysis in solution. We find that native GFPssrA structures are degraded in a biexponential process, which correlates strongly with ATP hydrolysis, the loss of fluorescence, and the buildup of small oligopeptide products. Our solution structural data support a model in which the substrate is directly translocated from PAN into the 20S proteolytic chamber, after a first, to our knowledge, successful unfolding process that represents a point of no return and thus prevents dissociation of the complex and the release of harmful, aggregation-prone products.
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Affiliation(s)
- Emilie Mahieu
- University Grenoble Alpes, CEA, CNRS, IBS, Grenoble, France
| | - Jacques Covès
- University Grenoble Alpes, CEA, CNRS, IBS, Grenoble, France
| | - Georg Krüger
- Leibniz University Hannover, Centre for Biomolecular Drug Research, Hannover, Germany
| | | | | | - Nico Carl
- Institut Laue-Langevin, Grenoble, France
| | | | - Teresa Carlomagno
- Leibniz University Hannover, Centre for Biomolecular Drug Research, Hannover, Germany; Group of Structural Chemistry, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | | | - Frank Gabel
- University Grenoble Alpes, CEA, CNRS, IBS, Grenoble, France; Institut Laue-Langevin, Grenoble, France.
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16
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Shin M, Puchades C, Asmita A, Puri N, Adjei E, Wiseman RL, Karzai AW, Lander GC. Structural basis for distinct operational modes and protease activation in AAA+ protease Lon. SCIENCE ADVANCES 2020; 6:eaba8404. [PMID: 32490208 PMCID: PMC7239648 DOI: 10.1126/sciadv.aba8404] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 03/09/2020] [Indexed: 05/21/2023]
Abstract
Substrate-bound structures of AAA+ protein translocases reveal a conserved asymmetric spiral staircase architecture wherein a sequential ATP hydrolysis cycle drives hand-over-hand substrate translocation. However, this configuration is unlikely to represent the full conformational landscape of these enzymes, as biochemical studies suggest distinct conformational states depending on the presence or absence of substrate. Here, we used cryo-electron microscopy to determine structures of the Yersinia pestis Lon AAA+ protease in the absence and presence of substrate, uncovering the mechanistic basis for two distinct operational modes. In the absence of substrate, Lon adopts a left-handed, "open" spiral organization with autoinhibited proteolytic active sites. Upon the addition of substrate, Lon undergoes a reorganization to assemble an enzymatically active, right-handed "closed" conformer with active protease sites. These findings define the mechanistic principles underlying the operational plasticity required for processing diverse protein substrates.
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Affiliation(s)
- Mia Shin
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Cristina Puchades
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Ananya Asmita
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Neha Puri
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Eric Adjei
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - R. Luke Wiseman
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - A. Wali Karzai
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Gabriel C. Lander
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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17
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AAA+ ATPases in Protein Degradation: Structures, Functions and Mechanisms. Biomolecules 2020; 10:biom10040629. [PMID: 32325699 PMCID: PMC7226402 DOI: 10.3390/biom10040629] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 03/21/2020] [Accepted: 03/30/2020] [Indexed: 12/28/2022] Open
Abstract
Adenosine triphosphatases (ATPases) associated with a variety of cellular activities (AAA+), the hexameric ring-shaped motor complexes located in all ATP-driven proteolytic machines, are involved in many cellular processes. Powered by cycles of ATP binding and hydrolysis, conformational changes in AAA+ ATPases can generate mechanical work that unfolds a substrate protein inside the central axial channel of ATPase ring for degradation. Three-dimensional visualizations of several AAA+ ATPase complexes in the act of substrate processing for protein degradation have been resolved at the atomic level thanks to recent technical advances in cryogenic electron microscopy (cryo-EM). Here, we summarize the resulting advances in structural and biochemical studies of AAA+ proteases in the process of proteolysis reactions, with an emphasis on cryo-EM structural analyses of the 26S proteasome, Cdc48/p97 and FtsH-like mitochondrial proteases. These studies reveal three highly conserved patterns in the structure–function relationship of AAA+ ATPase hexamers that were observed in the human 26S proteasome, thus suggesting common dynamic models of mechanochemical coupling during force generation and substrate translocation.
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18
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An Allosteric Interaction Network Promotes Conformation State-Dependent Eviction of the Nas6 Assembly Chaperone from Nascent 26S Proteasomes. Cell Rep 2020; 26:483-495.e5. [PMID: 30625330 PMCID: PMC6344052 DOI: 10.1016/j.celrep.2018.12.042] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 11/15/2018] [Accepted: 12/11/2018] [Indexed: 12/04/2022] Open
Abstract
The 26S proteasome is the central ATP-dependent protease in eukaryotes and is essential for organismal health. Proteasome assembly is mediated by several dedicated, evolutionarily conserved chaperone proteins. These chaperones associate transiently with assembly intermediates but are absent from mature proteasomes. Chaperone eviction upon completion of proteasome assembly is necessary for normal proteasome function, but how they are released remains unresolved. Here, we demonstrate that the Nas6 assembly chaperone, homolog of the human oncogene gankyrin, is evicted from nascent proteasomes during completion of assembly via a conformation-specific allosteric interaction of the Rpn5 subunit with the proteasomal ATPase ring. Subsequent ATP binding by the ATPase subunit Rpt3 promotes conformational remodeling of the ATPase ring that evicts Nas6 from the nascent proteasome. Our study demonstrates how assembly-coupled allosteric signals promote chaperone eviction and provides a framework for understanding the eviction of other chaperones from this bio-medically important molecular machine. Nemec et al. report how the evolutionarily conserved Nas6 assembly chaperone is evicted from nascent 26S proteasomes. Nucleotide binding events within the nascent proteasome trigger formation of conformation-specific intersubunit contacts that expel Nas6. This mechanism may serve a quality control function by blocking formation of 26S proteasomes from defective components.
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19
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Eisele MR, Reed RG, Rudack T, Schweitzer A, Beck F, Nagy I, Pfeifer G, Plitzko JM, Baumeister W, Tomko RJ, Sakata E. Expanded Coverage of the 26S Proteasome Conformational Landscape Reveals Mechanisms of Peptidase Gating. Cell Rep 2019; 24:1301-1315.e5. [PMID: 30067984 PMCID: PMC6140342 DOI: 10.1016/j.celrep.2018.07.004] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 06/08/2018] [Accepted: 07/02/2018] [Indexed: 12/31/2022] Open
Abstract
The proteasome is the central protease for intracellular protein breakdown. Coordinated binding and hydrolysis of ATP by the six proteasomal ATPase subunits induces conformational changes that drive the unfolding and translocation of substrates into the proteolytic 20S core particle for degradation. Here, we combine genetic and biochemical approaches with cryo-electron microscopy and integrative modeling to dissect the relationship between individual nucleotide binding events and proteasome conformational dynamics. We demonstrate unique impacts of ATP binding by individual ATPases on the proteasome conformational distribution and report two conformational states of the proteasome suggestive of a rotary ATP hydrolysis mechanism. These structures, coupled with functional analyses, reveal key roles for the ATPases Rpt1 and Rpt6 in gating substrate entry into the core particle. This deepened knowledge of proteasome conformational dynamics reveals key elements of intersubunit communication within the proteasome and clarifies the regulation of substrate entry into the proteolytic chamber.
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Affiliation(s)
- Markus R Eisele
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Randi G Reed
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL 32306-4300, USA
| | - Till Rudack
- Department of Biophysics, Ruhr University Bochum, 44801 Bochum, Germany
| | - Andreas Schweitzer
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Florian Beck
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Istvan Nagy
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Günter Pfeifer
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Jürgen M Plitzko
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Wolfgang Baumeister
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
| | - Robert J Tomko
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL 32306-4300, USA.
| | - Eri Sakata
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
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20
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Activation of the unfolded protein response in high glucose treated endothelial cells is mediated by methylglyoxal. Sci Rep 2019; 9:7889. [PMID: 31133647 PMCID: PMC6536510 DOI: 10.1038/s41598-019-44358-1] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 11/21/2018] [Indexed: 12/31/2022] Open
Abstract
Metabolic dysfunction of endothelial cells in hyperglycemia contributes to the development of vascular complications of diabetes where increased reactive glycating agent, methylglyoxal (MG), is involved. We assessed if increased MG glycation induced proteotoxic stress, identifying related metabolic drivers and protein targets. Human aortal endothelial cells (HAECs) were incubated in high glucose concentration (20 mM versus 5 mM control) in vitro for 3–6 days. Flux of glucose metabolism, MG formation and glycation and changes in cytosolic protein abundances, MG modification and proteotoxic responses were assessed. Similar studies were performed with human microvascular endothelial HMEC-1 cells where similar outcomes were observed. HAECs exposed to high glucose concentration showed increased cellular concentration of MG (2.27 ± 0.21 versus 1.28 ± 0.03 pmol/106 cells, P < 0.01) and formation of MG-modified proteins (24.0 ± 3.7 versus 14.1 ± 3.2 pmol/106 cells/day; P < 0.001). In proteomics analysis, high glucose concentration increased proteins of the heat shock response – indicating activation of the unfolded protein response (UPR) with downstream inflammatory and pro-thrombotic responses. Proteins susceptible to MG modification were enriched in protein folding, protein synthesis, serine/threonine kinase signalling, glycolysis and gluconeogenesis. MG was increased in high glucose by increased flux of MG formation linked to increased glucose metabolism mediated by proteolytic stabilisation and increase of hexokinase-2 (HK-2); later potentiated by proteolytic down regulation of glyoxalase 1 (Glo1) - the major enzyme of MG metabolism. Silencing of Glo1, selectively increasing MG, activated the UPR similarly. Silencing of HK-2 prevented increased glucose metabolism and MG formation. trans-Resveratrol and hesperetin combination (tRES-HESP) corrected increased MG and glucose metabolism by increasing expression of Glo1 and decreasing expression of HK-2. Increased MG glycation activates the UPR in endothelial cells and thereby may contribute to endothelial cell dysfunction in diabetic vascular disease where tRES-HESP may provide effective therapy.
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21
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Abstract
Ubiquitin-like protein (Ubl) ligation is common to diverse archaea and targets many cellular pathways, including those associated with sulfur mobilization, and also tags proteins as substrates for degradation by the proteasome. Here we highlight protocols to assay proteasome function and Ubl ligation in archaea. A chase assay is described to monitor the impact of proteasome function on the stability of Ubl-modified proteins in the cell. A method to reconstitute Ubl ligation using a purified E1-like enzyme (UbaA), Ubl (SAMP2), methionine sulfoxide reductase A (MsrA), and cell lysate of an ΔmsrA ΔubaA Δsamp1-3 mutant is also described. MsrA is found to have the surprising ability to stimulate the formation of Ubl bonds. Haloferax volcanii, a halophilic archaeon originally isolated from the Dead Sea, serves as the model organism for these protocols.
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22
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Brambley CA, Marsee JD, Halper N, Miller JM. Characterization of Mitochondrial YME1L Protease Oxidative Stress-Induced Conformational State. J Mol Biol 2019; 431:1250-1266. [PMID: 30731091 DOI: 10.1016/j.jmb.2019.01.039] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 01/11/2019] [Accepted: 01/27/2019] [Indexed: 10/27/2022]
Abstract
Oxidative stress is a common challenge to mitochondrial function where reactive oxygen species are capable of significant organelle damage. The generation of mitochondrial reactive oxygen species occurs in the inner membrane and matrix compartments as a consequence of subunit function in the electron transport chain and citric acid cycle, respectively. Maintenance of mitochondrial proteostasis and stress response is facilitated by compartmentalized proteases that couple the energy of ATP hydrolysis to unfolding and the regulated removal of damaged, misfolded, or aggregated proteins. The mitochondrial protease YME1L functions in the maintenance of proteostasis in the intermembrane space. YME1L is an inner membrane-anchored hexameric protease with distinct N-terminal, transmembrane, AAA+ (ATPases associated with various cellular activities), and C-terminal M41 zinc-dependent protease domains. The effect of oxidative stress on enzymes such as YME1L tasked with maintaining proteostasis is currently unclear. We report here that recombinant YME1L undergoes a reversible conformational change in response to oxidative stress that involves the interaction of one hydrogen peroxide molecule per YME1L monomer with affinities equal to 31 ± 2 and 26 ± 1 mM for conditions lacking or including nucleotide, respectively. Our data also reveal that oxidative stress does not significantly impact nucleotide binding equilibria, but does stimulate a 2-fold increase in the rate constant for high-affinity ATP binding from (8.9 ± 0.2) × 105 M-1 s-1 to (1.5 ± 0.1) × 106 M-1 s-1. Taken together, these data may suggest a mechanism for the regulated processing of YME1L by other inner membrane proteases such as OMA1.
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Affiliation(s)
- Chad A Brambley
- Department of Chemistry, Middle Tennessee State University, 1301 East Main Street, Murfreesboro, TN 37132, USA
| | - Justin D Marsee
- Department of Chemistry, Middle Tennessee State University, 1301 East Main Street, Murfreesboro, TN 37132, USA
| | - Neal Halper
- Department of Chemistry, Middle Tennessee State University, 1301 East Main Street, Murfreesboro, TN 37132, USA
| | - Justin M Miller
- Department of Chemistry, Middle Tennessee State University, 1301 East Main Street, Murfreesboro, TN 37132, USA.
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23
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Stepping up protein degradation. Proc Natl Acad Sci U S A 2019; 116:350-352. [PMID: 30567974 DOI: 10.1073/pnas.1819949116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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24
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Abstract
Proteasomes are a class of protease that carry out the degradation of a specific set of cellular proteins. While essential for eukaryotic life, proteasomes are found only in a small subset of bacterial species. In this chapter, we present the current knowledge of bacterial proteasomes, detailing the structural features and catalytic activities required to achieve proteasomal proteolysis. We describe the known mechanisms by which substrates are doomed for degradation, and highlight potential non-degradative roles for components of bacterial proteasome systems. Additionally, we highlight several pathways of microbial physiology that rely on proteasome activity. Lastly, we explain the various gaps in our understanding of bacterial proteasome function and emphasize several opportunities for further study.
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Affiliation(s)
- Samuel H Becker
- Department of Microbiology, New York University School of Medicine, 430 E. 29th Street, Room 312, New York, NY, 10016, USA
| | - Huilin Li
- Van Andel Research Institute, Cryo-EM Structural Biology Laboratory, 333 Bostwick Ave, NE, Grand Rapids, MI, 4950, USA
| | - K Heran Darwin
- Department of Microbiology, New York University School of Medicine, 430 E. 29th Street, Room 312, New York, NY, 10016, USA.
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25
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Cryo-EM structures of the archaeal PAN-proteasome reveal an around-the-ring ATPase cycle. Proc Natl Acad Sci U S A 2018; 116:534-539. [PMID: 30559193 PMCID: PMC6329974 DOI: 10.1073/pnas.1817752116] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Proteasomes are ATP-dependent proteases that occur in all three domains of life, and are the principal molecular machines for the regulated degradation of intracellular proteins. The eukaryotic 26S proteasome has been extensively characterized. However, its evolutionary precursor, the archaeal proteasome–ATPase complex, remains poorly understood. The inherent instability of these primordial protein complexes has so far hindered attempts for detailed structure determination. Using cryo-EM single-particle analysis, we were able to determine the structure of an archaeal PAN-proteasome, which is a complex of the proteolytic core and the ATPase PAN (proteasome-activating nucleotidase). The structures reported here not only provide insights into the functional cycle of PAN-proteasomes, they reveal a fundamental mechanism of ATPase operation. Proteasomes occur in all three domains of life, and are the principal molecular machines for the regulated degradation of intracellular proteins. They play key roles in the maintenance of protein homeostasis, and control vital cellular processes. While the eukaryotic 26S proteasome is extensively characterized, its putative evolutionary precursor, the archaeal proteasome, remains poorly understood. The primordial archaeal proteasome consists of a 20S proteolytic core particle (CP), and an AAA-ATPase module. This minimal complex degrades protein unassisted by non-ATPase subunits that are present in a 26S proteasome regulatory particle (RP). Using cryo-EM single-particle analysis, we determined structures of the archaeal CP in complex with the AAA-ATPase PAN (proteasome-activating nucleotidase). Five conformational states were identified, elucidating the functional cycle of PAN, and its interaction with the CP. Coexisting nucleotide states, and correlated intersubunit signaling features, coordinate rotation of the PAN-ATPase staircase, and allosterically regulate N-domain motions and CP gate opening. These findings reveal the structural basis for a sequential around-the-ring ATPase cycle, which is likely conserved in AAA-ATPases.
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26
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Kammerl IE, Caniard A, Merl-Pham J, Ben-Nissan G, Mayr CH, Mossina A, Geerlof A, Eickelberg O, Hauck SM, Sharon M, Meiners S. Dissecting the molecular effects of cigarette smoke on proteasome function. J Proteomics 2018; 193:1-9. [PMID: 30557664 DOI: 10.1016/j.jprot.2018.12.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 12/11/2018] [Accepted: 12/13/2018] [Indexed: 01/02/2023]
Abstract
Proteasome dysfunction is emerging as a novel pathomechanism for the development of chronic obstructive pulmonary disease (COPD), a major leading cause of death in the world. Cigarette smoke, one of the main risk factors for COPD, impairs proteasome function in vitro and in vivo. In the present study, we dissected the molecular changes induced by cigarette smoke on the proteasome in lung epithelial cells and mouse lungs. 26S proteasome pull-down, MS interactome, and stoichiometry analyses indicated that 26S proteasome complexes become instable in cigarette smoke-treated lung epithelial cells as well as in lungs of mice after three day smoke exposure. The interactome of the 26S was clearly altered in mouse lungs upon smoke exposure but not in cells after 24 h of smoke exposure. Using native MS analysis of purified 20S proteasomes, we observed some destabilization of 20S complexes purified from cigarette smoke-exposed cells in the absence of any dominant and inhibitory modification of proteasomal proteins. Taken together, our results suggest that cigarette smoke induces minor but detectable changes in the stability of 20S and 26S proteasome complexes which might contribute to imbalanced proteostasis in a chronic setting as observed in chronic lung diseases associated with cigarette smoking.
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Affiliation(s)
- Ilona E Kammerl
- Comprehensive Pneumology Center (CPC), University Hospital, Ludwig-Maximilians University, Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Munich, Germany
| | - Anne Caniard
- Comprehensive Pneumology Center (CPC), University Hospital, Ludwig-Maximilians University, Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Munich, Germany
| | - Juliane Merl-Pham
- Research Unit Protein Science, Helmholtz Zentrum München, Munich, Germany
| | - Gili Ben-Nissan
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Christoph H Mayr
- Comprehensive Pneumology Center (CPC), University Hospital, Ludwig-Maximilians University, Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Munich, Germany
| | - Alessandra Mossina
- Comprehensive Pneumology Center (CPC), University Hospital, Ludwig-Maximilians University, Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Munich, Germany
| | - Arie Geerlof
- Protein Expression and Purification Facility (PEPF), Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany
| | - Oliver Eickelberg
- Division of Respiratory and Critical Care Medicine, University of Colorado, Aurora, USA
| | - Stefanie M Hauck
- Research Unit Protein Science, Helmholtz Zentrum München, Munich, Germany
| | - Michal Sharon
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Silke Meiners
- Comprehensive Pneumology Center (CPC), University Hospital, Ludwig-Maximilians University, Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Munich, Germany.
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27
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Proteolytic systems of archaea: slicing, dicing, and mincing in the extreme. Emerg Top Life Sci 2018; 2:561-580. [PMID: 32953999 DOI: 10.1042/etls20180025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Archaea are phylogenetically distinct from bacteria, and some of their proteolytic systems reflect this distinction. Here, the current knowledge of archaeal proteolysis is reviewed as it relates to protein metabolism, protein homeostasis, and cellular regulation including targeted proteolysis by proteasomes associated with AAA-ATPase networks and ubiquitin-like modification. Proteases and peptidases that facilitate the recycling of peptides to amino acids as well as membrane-associated and integral membrane proteases are also reviewed.
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28
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Dong Y, Zhang S, Wu Z, Li X, Wang WL, Zhu Y, Stoilova-McPhie S, Lu Y, Finley D, Mao Y. Cryo-EM structures and dynamics of substrate-engaged human 26S proteasome. Nature 2018; 565:49-55. [PMID: 30479383 PMCID: PMC6370054 DOI: 10.1038/s41586-018-0736-4] [Citation(s) in RCA: 210] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 11/02/2018] [Indexed: 11/15/2022]
Abstract
The proteasome is an ATP-dependent, 2.5-megadalton machine responsible for selective protein degradation in eukaryotic cells. Here we present cryo-EM structures of the substrate-engaged human proteasome in seven conformational states at 2.8-3.6 Å resolution, captured during breakdown of a polyubiquitylated protein. These structures visualize a continuum of dynamic substrate-proteasome interactions from ubiquitin recognition to substrate translocation, during which ATP hydrolysis sequentially navigates through all six ATPases. Three principal modes of coordinated hydrolysis are observed, featuring hydrolytic events in two oppositely positioned ATPases, in two adjacent ATPases, and in one ATPase at a time. These hydrolytic modes regulate deubiquitylation, translocation initiation and processive unfolding of substrates, respectively. ATP hydrolysis powers a hinge-like motion in each ATPase that regulates its substrate interaction. Synchronization of ATP binding, ADP release and ATP hydrolysis in three adjacent ATPases drives rigid-body rotations of substrate-bound ATPases that are propagated unidirectionally in the ATPase ring and unfold the substrate.
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Affiliation(s)
- Yuanchen Dong
- State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing, China.,Intel Parallel Computing Center for Structural Biology, Dana-Farber Cancer Institute, Boston, MA, USA.,Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, USA.,Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, USA
| | - Shuwen Zhang
- State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing, China.,Center for Quantitative Biology, Peking University, Beijing, China
| | - Zhaolong Wu
- State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing, China
| | - Xuemei Li
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, China
| | - Wei Li Wang
- State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing, China.,Intel Parallel Computing Center for Structural Biology, Dana-Farber Cancer Institute, Boston, MA, USA.,Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, USA.,Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, USA
| | - Yanan Zhu
- State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing, China.,Center for Quantitative Biology, Peking University, Beijing, China
| | | | - Ying Lu
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA
| | - Daniel Finley
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Youdong Mao
- State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing, China. .,Intel Parallel Computing Center for Structural Biology, Dana-Farber Cancer Institute, Boston, MA, USA. .,Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, USA. .,Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, USA. .,Center for Quantitative Biology, Peking University, Beijing, China. .,Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, China.
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29
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Snoberger A, Brettrager EJ, Smith DM. Conformational switching in the coiled-coil domains of a proteasomal ATPase regulates substrate processing. Nat Commun 2018; 9:2374. [PMID: 29915197 PMCID: PMC6006169 DOI: 10.1038/s41467-018-04731-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 05/18/2018] [Indexed: 12/15/2022] Open
Abstract
Protein degradation in all domains of life requires ATPases that unfold and inject proteins into compartmentalized proteolytic chambers. Proteasomal ATPases in eukaryotes and archaea contain poorly understood N-terminally conserved coiled-coil domains. In this study, we engineer disulfide crosslinks in the coiled-coils of the archaeal proteasomal ATPase (PAN) and report that its three identical coiled-coil domains can adopt three different conformations: (1) in-register and zipped, (2) in-register and partially unzipped, and (3) out-of-register. This conformational heterogeneity conflicts with PAN's symmetrical OB-coiled-coil crystal structure but resembles the conformational heterogeneity of the 26S proteasomal ATPases' coiled-coils. Furthermore, we find that one coiled-coil can be conformationally constrained even while unfolding substrates, and conformational changes in two of the coiled-coils regulate PAN switching between resting and active states. This switching functionally mimics similar states proposed for the 26S proteasome from cryo-EM. These findings thus build a mechanistic framework to understand regulation of proteasome activity.
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Affiliation(s)
- Aaron Snoberger
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, WV, 26506, USA
| | - Evan J Brettrager
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, WV, 26506, USA
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL, 26501, USA
| | - David M Smith
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, WV, 26506, USA.
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30
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The type IV pilus assembly motor PilB is a robust hexameric ATPase with complex kinetics. Biochem J 2018; 475:1979-1993. [PMID: 29717025 DOI: 10.1042/bcj20180167] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 04/23/2018] [Accepted: 05/01/2018] [Indexed: 01/06/2023]
Abstract
The bacterial type IV pilus (T4P) is a versatile nanomachine that functions in pathogenesis, biofilm formation, motility, and horizontal gene transfer. T4P assembly is powered by the motor ATPase PilB which is proposed to hydrolyze ATP by a symmetrical rotary mechanism. This mechanism, which is deduced from the structure of PilB, is untested. Here, we report the first kinetic studies of the PilB ATPase, supporting co-ordination among the protomers of this hexameric enzyme. Analysis of the genome sequence of Chloracidobacterium thermophilum identified a pilB gene whose protein we then heterologously expressed. This PilB formed a hexamer in solution and exhibited highly robust ATPase activity. It displays complex steady-state kinetics with an incline followed by a decline over an ATP concentration range of physiological relevance. The incline is multiphasic and the decline signifies substrate inhibition. These observations suggest that variations in intracellular ATP concentrations may regulate T4P assembly and T4P-mediated functions in vivo in accordance with the physiological state of bacteria with unanticipated complexity. We also identified a mutant pilB gene in the genomic DNA of C. thermophilum from an enrichment culture. The mutant PilB variant, which is significantly less active, exhibited similar inhibition of its ATPase activity by high concentrations of ATP. Our findings here with the PilB ATPase from C. thermophilum provide the first line of biochemical evidence for the co-ordination among PilB protomers consistent with the symmetrical rotary model of catalysis based on structural studies.
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31
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Bard JAM, Goodall EA, Greene ER, Jonsson E, Dong KC, Martin A. Structure and Function of the 26S Proteasome. Annu Rev Biochem 2018; 87:697-724. [PMID: 29652515 DOI: 10.1146/annurev-biochem-062917-011931] [Citation(s) in RCA: 441] [Impact Index Per Article: 73.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
As the endpoint for the ubiquitin-proteasome system, the 26S proteasome is the principal proteolytic machine responsible for regulated protein degradation in eukaryotic cells. The proteasome's cellular functions range from general protein homeostasis and stress response to the control of vital processes such as cell division and signal transduction. To reliably process all the proteins presented to it in the complex cellular environment, the proteasome must combine high promiscuity with exceptional substrate selectivity. Recent structural and biochemical studies have shed new light on the many steps involved in proteasomal substrate processing, including recognition, deubiquitination, and ATP-driven translocation and unfolding. In addition, these studies revealed a complex conformational landscape that ensures proper substrate selection before the proteasome commits to processive degradation. These advances in our understanding of the proteasome's intricate machinery set the stage for future studies on how the proteasome functions as a major regulator of the eukaryotic proteome.
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Affiliation(s)
- Jared A M Bard
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA; .,California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, California 94720, USA
| | - Ellen A Goodall
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA; .,California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, California 94720, USA
| | - Eric R Greene
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA; .,California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, California 94720, USA
| | - Erik Jonsson
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA; .,California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, California 94720, USA.,Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, California 94720, USA
| | - Ken C Dong
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA; .,California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, California 94720, USA.,Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, California 94720, USA
| | - Andreas Martin
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA; .,California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, California 94720, USA.,Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, California 94720, USA
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32
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Pöhler R, Krahn JH, van den Boom J, Dobrynin G, Kaschani F, Eggenweiler HM, Zenke FT, Kaiser M, Meyer H. A Non-Competitive Inhibitor of VCP/p97 and VPS4 Reveals Conserved Allosteric Circuits in Type I and II AAA ATPases. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201711429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Robert Pöhler
- Molecular Biology I, Centre for Medical Biotechnology; University of Duisburg-Essen; 45117 Essen Germany
| | - Jan H. Krahn
- Chemical Biology, Centre for Medical Biotechnology; University of Duisburg-Essen; 45117 Essen Germany
| | - Johannes van den Boom
- Molecular Biology I, Centre for Medical Biotechnology; University of Duisburg-Essen; 45117 Essen Germany
| | - Grzegorz Dobrynin
- Molecular Biology I, Centre for Medical Biotechnology; University of Duisburg-Essen; 45117 Essen Germany
| | - Farnusch Kaschani
- Chemical Biology, Centre for Medical Biotechnology; University of Duisburg-Essen; 45117 Essen Germany
| | - Hans-Michael Eggenweiler
- Medicinal Chemistry DA and Translational Innovation Platform Oncology, Global R&D, Healthcare; Merck KGaA; Frankfurter Str. 250 64293 Darmstadt Germany
| | - Frank T. Zenke
- Medicinal Chemistry DA and Translational Innovation Platform Oncology, Global R&D, Healthcare; Merck KGaA; Frankfurter Str. 250 64293 Darmstadt Germany
| | - Markus Kaiser
- Chemical Biology, Centre for Medical Biotechnology; University of Duisburg-Essen; 45117 Essen Germany
| | - Hemmo Meyer
- Molecular Biology I, Centre for Medical Biotechnology; University of Duisburg-Essen; 45117 Essen Germany
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33
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Pöhler R, Krahn JH, van den Boom J, Dobrynin G, Kaschani F, Eggenweiler HM, Zenke FT, Kaiser M, Meyer H. A Non-Competitive Inhibitor of VCP/p97 and VPS4 Reveals Conserved Allosteric Circuits in Type I and II AAA ATPases. Angew Chem Int Ed Engl 2018; 57:1576-1580. [PMID: 29271116 DOI: 10.1002/anie.201711429] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 12/15/2017] [Indexed: 01/16/2023]
Abstract
AAA ATPases have pivotal functions in diverse cellular processes essential for survival and proliferation. Revealing strategies for chemical inhibition of this class of enzymes is therefore of great interest for the development of novel chemotherapies or chemical tools. Here, we characterize the compound MSC1094308 as a reversible, allosteric inhibitor of the type II AAA ATPase human ubiquitin-directed unfoldase (VCP)/p97 and the type I AAA ATPase VPS4B. Subsequent proteomic, genetic and biochemical studies indicate that MSC1094308 binds to a previously characterized drugable hotspot of p97, thereby inhibiting the D2 ATPase activity. Our results furthermore indicate that a similar allosteric site exists in VPS4B, suggesting conserved allosteric circuits and drugable sites in both type I and II AAA ATPases. Our results may thus guide future chemical tool and drug discovery efforts for the biomedically relevant AAA ATPases.
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Affiliation(s)
- Robert Pöhler
- Molecular Biology I, Centre for Medical Biotechnology, University of Duisburg-Essen, 45117, Essen, Germany
| | - Jan H Krahn
- Chemical Biology, Centre for Medical Biotechnology, University of Duisburg-Essen, 45117, Essen, Germany
| | - Johannes van den Boom
- Molecular Biology I, Centre for Medical Biotechnology, University of Duisburg-Essen, 45117, Essen, Germany
| | - Grzegorz Dobrynin
- Molecular Biology I, Centre for Medical Biotechnology, University of Duisburg-Essen, 45117, Essen, Germany
| | - Farnusch Kaschani
- Chemical Biology, Centre for Medical Biotechnology, University of Duisburg-Essen, 45117, Essen, Germany
| | - Hans-Michael Eggenweiler
- Medicinal Chemistry DA and Translational Innovation Platform Oncology, Global R&D, Healthcare, Merck KGaA, Frankfurter Str. 250, 64293, Darmstadt, Germany
| | - Frank T Zenke
- Medicinal Chemistry DA and Translational Innovation Platform Oncology, Global R&D, Healthcare, Merck KGaA, Frankfurter Str. 250, 64293, Darmstadt, Germany
| | - Markus Kaiser
- Chemical Biology, Centre for Medical Biotechnology, University of Duisburg-Essen, 45117, Essen, Germany
| | - Hemmo Meyer
- Molecular Biology I, Centre for Medical Biotechnology, University of Duisburg-Essen, 45117, Essen, Germany
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34
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Ahdash Z, Lau AM, Byrne RT, Lammens K, Stüetzer A, Urlaub H, Booth PJ, Reading E, Hopfner KP, Politis A. Mechanistic insight into the assembly of the HerA-NurA helicase-nuclease DNA end resection complex. Nucleic Acids Res 2017; 45:12025-12038. [PMID: 29149348 PMCID: PMC5715905 DOI: 10.1093/nar/gkx890] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 09/20/2017] [Accepted: 09/22/2017] [Indexed: 01/08/2023] Open
Abstract
The HerA-NurA helicase-nuclease complex cooperates with Mre11 and Rad50 to coordinate the repair of double-stranded DNA breaks. Little is known, however, about the assembly mechanism and activation of the HerA-NurA. By combining hybrid mass spectrometry with cryo-EM, computational and biochemical data, we investigate the oligomeric formation of HerA and detail the mechanism of nucleotide binding to the HerA-NurA complex from thermophilic archaea. We reveal that ATP-free HerA and HerA-DNA complexes predominantly exist in solution as a heptamer and act as a DNA loading intermediate. The binding of either NurA or ATP stabilizes the hexameric HerA, indicating that HerA-NurA is activated by substrates and complex assembly. To examine the role of ATP in DNA translocation and processing, we investigated how nucleotides interact with the HerA-NurA. We show that while the hexameric HerA binds six nucleotides in an 'all-or-none' fashion, HerA-NurA harbors a highly coordinated pairwise binding mechanism and enables the translocation and processing of double-stranded DNA. Using molecular dynamics simulations, we reveal novel inter-residue interactions between the external ATP and the internal DNA binding sites. Overall, here we propose a stepwise assembly mechanism detailing the synergistic activation of HerA-NurA by ATP, which allows efficient processing of double-stranded DNA.
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Affiliation(s)
- Zainab Ahdash
- Department of Chemistry, King's College London, 7 Trinity Street, London SE1 1DB, UK
| | - Andy M. Lau
- Department of Chemistry, King's College London, 7 Trinity Street, London SE1 1DB, UK
| | - Robert Thomas Byrne
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 München, Germany
| | - Katja Lammens
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 München, Germany
| | - Alexandra Stüetzer
- Bioanalytical Mass Spectrometry Group, MPI for Biophysical Chemistry, D-37077 Göttingen, Germany
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Group, MPI for Biophysical Chemistry, D-37077 Göttingen, Germany
- Bioanalytics Group, Institute for Clinical Chemistry, University Medical Center Göttingen, D-37075 Göttingen, Germany
| | - Paula J. Booth
- Department of Chemistry, King's College London, 7 Trinity Street, London SE1 1DB, UK
| | - Eamonn Reading
- Department of Chemistry, King's College London, 7 Trinity Street, London SE1 1DB, UK
| | - Karl-Peter Hopfner
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 München, Germany
| | - Argyris Politis
- Department of Chemistry, King's College London, 7 Trinity Street, London SE1 1DB, UK
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35
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The Logic of the 26S Proteasome. Cell 2017; 169:792-806. [PMID: 28525752 DOI: 10.1016/j.cell.2017.04.023] [Citation(s) in RCA: 562] [Impact Index Per Article: 80.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 04/13/2017] [Accepted: 04/14/2017] [Indexed: 12/14/2022]
Abstract
The ubiquitin proteasome pathway is responsible for most of the protein degradation in mammalian cells. Rates of degradation by this pathway have generally been assumed to be determined by rates of ubiquitylation. However, recent studies indicate that proteasome function is also tightly regulated and determines whether a ubiquitylated protein is destroyed or deubiquitylated and survives longer. This article reviews recent advances in our understanding of the proteasome's multistep ATP-dependent mechanism, its biochemical and structural features that ensure efficient proteolysis and ubiquitin recycling while preventing nonselective proteolysis, and the regulation of proteasome activity by interacting proteins and subunit modifications, especially phosphorylation.
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36
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Yedidi RS, Wendler P, Enenkel C. AAA-ATPases in Protein Degradation. Front Mol Biosci 2017; 4:42. [PMID: 28676851 PMCID: PMC5476697 DOI: 10.3389/fmolb.2017.00042] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2017] [Accepted: 06/06/2017] [Indexed: 11/13/2022] Open
Abstract
Proteolytic machineries containing multisubunit protease complexes and AAA-ATPases play a key role in protein quality control and the regulation of protein homeostasis. In these protein degradation machineries, the proteolytically active sites are formed by either threonines or serines which are buried inside interior cavities of cylinder-shaped complexes. In eukaryotic cells, the proteasome is the most prominent protease complex harboring AAA-ATPases. To degrade protein substrates, the gates of the axial entry ports of the protease need to be open. Gate opening is accomplished by AAA-ATPases, which form a hexameric ring flanking the entry ports of the protease. Protein substrates with unstructured domains can loop into the entry ports without the assistance of AAA-ATPases. However, folded proteins require the action of AAA-ATPases to unveil an unstructured terminus or domain. Cycles of ATP binding/hydrolysis fuel the unfolding of protein substrates which are gripped by loops lining up the central pore of the AAA-ATPase ring. The AAA-ATPases pull on the unfolded polypeptide chain for translocation into the proteolytic cavity of the protease. Conformational changes within the AAA-ATPase ring and the adjacent protease chamber create a peristaltic movement for substrate degradation. The review focuses on new technologies toward the understanding of the function and structure of AAA-ATPases to achieve substrate recognition, unfolding and translocation into proteasomes in yeast and mammalian cells and into proteasome-equivalent proteases in bacteria and archaea.
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Affiliation(s)
| | - Petra Wendler
- Department of Biochemistry, Institute of Biochemistry and Biology, University of PotsdamPotsdam, Germany
| | - Cordula Enenkel
- Department of Biochemistry, University of TorontoToronto, ON, Canada
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37
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Wu Y, Hu K, Li D, Bai L, Yang S, Jastrab JB, Xiao S, Hu Y, Zhang S, Darwin KH, Wang T, Li H. Mycobacterium tuberculosis proteasomal ATPase Mpa has a β-grasp domain that hinders docking with the proteasome core protease. Mol Microbiol 2017; 105:227-241. [PMID: 28419599 DOI: 10.1111/mmi.13695] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/12/2017] [Indexed: 12/21/2022]
Abstract
Mycobacterium tuberculosis (Mtb) has a proteasome system that is essential for its ability to cause lethal infections in mice. A key component of the system is the proteasomal adenosine triphosphatase (ATPase) Mpa, which captures, unfolds, and translocates protein substrates into the Mtb proteasome core particle for degradation. Here, we report the crystal structures of near full-length hexameric Mtb Mpa in apo and ADP-bound forms. Surprisingly, the structures revealed a ubiquitin-like β-grasp domain that precedes the proteasome-activating carboxyl terminus. This domain, which was only found in bacterial proteasomal ATPases, buries the carboxyl terminus of each protomer in the central channel of the hexamer and hinders the interaction of Mpa with the proteasome core protease. Thus, our work reveals the structure of a bacterial proteasomal ATPase in the hexameric form, and the structure finally explains why Mpa is unable to stimulate robust protein degradation in vitro in the absence of other, yet-to-be-identified co-factors.
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Affiliation(s)
- Yujie Wu
- Department of Biology, Southern University of Science and Technology, 1088 Xueyuan Road, Nanshan District, Shenzhen, 518055, China
| | - Kuan Hu
- Cryo-EM Structural Biology Laboratory, Van Andel Research Institute, Grand Rapids, MI, 49503, USA.,Biochemistry and Structural Biology Graduate Program, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Defeng Li
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing, 100101, China
| | - Lin Bai
- Cryo-EM Structural Biology Laboratory, Van Andel Research Institute, Grand Rapids, MI, 49503, USA
| | - Shaoqing Yang
- Cryo-EM Structural Biology Laboratory, Van Andel Research Institute, Grand Rapids, MI, 49503, USA
| | - Jordan B Jastrab
- Department of Microbiology, New York University School of Medicine, 450 East 29th Street, New York, NY, 10016, USA
| | - Shuhao Xiao
- Department of Biology, Southern University of Science and Technology, 1088 Xueyuan Road, Nanshan District, Shenzhen, 518055, China
| | - Yonglin Hu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing, 100101, China
| | - Susan Zhang
- Department of Microbiology, New York University School of Medicine, 450 East 29th Street, New York, NY, 10016, USA
| | - K Heran Darwin
- Department of Microbiology, New York University School of Medicine, 450 East 29th Street, New York, NY, 10016, USA
| | - Tao Wang
- Department of Biology, Southern University of Science and Technology, 1088 Xueyuan Road, Nanshan District, Shenzhen, 518055, China.,SZCDC-SUSTech Joint Key Laboratory for Tropical Diseases, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, China
| | - Huilin Li
- Cryo-EM Structural Biology Laboratory, Van Andel Research Institute, Grand Rapids, MI, 49503, USA
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38
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Ripstein ZA, Huang R, Augustyniak R, Kay LE, Rubinstein JL. Structure of a AAA+ unfoldase in the process of unfolding substrate. eLife 2017; 6. [PMID: 28390173 PMCID: PMC5423775 DOI: 10.7554/elife.25754] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 04/06/2017] [Indexed: 12/19/2022] Open
Abstract
AAA+ unfoldases are thought to unfold substrate through the central pore of their hexameric structures, but how this process occurs is not known. VAT, the Thermoplasma acidophilum homologue of eukaryotic CDC48/p97, works in conjunction with the proteasome to degrade misfolded or damaged proteins. We show that in the presence of ATP, VAT with its regulatory N-terminal domains removed unfolds other VAT complexes as substrate. We captured images of this transient process by electron cryomicroscopy (cryo-EM) to reveal the structure of the substrate-bound intermediate. Substrate binding breaks the six-fold symmetry of the complex, allowing five of the six VAT subunits to constrict into a tight helix that grips an ~80 Å stretch of unfolded protein. The structure suggests a processive hand-over-hand unfolding mechanism, where each VAT subunit releases the substrate in turn before re-engaging further along the target protein, thereby unfolding it.
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Affiliation(s)
- Zev A Ripstein
- The Hospital for Sick Children Research Institute, Toronto, Canada.,Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Rui Huang
- Department of Biochemistry, University of Toronto, Toronto, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Canada.,Department of Chemistry, University of Toronto, Toronto, Canada
| | - Rafal Augustyniak
- Department of Biochemistry, University of Toronto, Toronto, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Canada.,Department of Chemistry, University of Toronto, Toronto, Canada
| | - Lewis E Kay
- The Hospital for Sick Children Research Institute, Toronto, Canada.,Department of Biochemistry, University of Toronto, Toronto, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Canada.,Department of Chemistry, University of Toronto, Toronto, Canada
| | - John L Rubinstein
- The Hospital for Sick Children Research Institute, Toronto, Canada.,Department of Biochemistry, University of Toronto, Toronto, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Canada
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39
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Snoberger A, Anderson RT, Smith DM. The Proteasomal ATPases Use a Slow but Highly Processive Strategy to Unfold Proteins. Front Mol Biosci 2017; 4:18. [PMID: 28421184 PMCID: PMC5378721 DOI: 10.3389/fmolb.2017.00018] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 03/16/2017] [Indexed: 01/23/2023] Open
Abstract
All domains of life have ATP-dependent compartmentalized proteases that sequester their peptidase sites on their interior. ATPase complexes will often associate with these compartmentalized proteases in order to unfold and inject substrates into the protease for degradation. Significant effort has been put into understanding how ATP hydrolysis is used to apply force to proteins and cause them to unfold. The unfolding kinetics of the bacterial ATPase, ClpX, have been shown to resemble a fast motor that traps unfolded intermediates as a strategy to unfold proteins. In the present study, we sought to determine if the proteasomal ATPases from eukaryotes and archaea exhibit similar unfolding kinetics. We found that the proteasomal ATPases appear to use a different kinetic strategy for protein unfolding, behaving as a slower but more processive and efficient translocation motor, particularly when encountering a folded domain. We expect that these dissimilarities are due to differences in the ATP binding/exchange cycle, the presence of a trans-arginine finger, or the presence of a threading ring (i.e., the OB domain), which may be used as a rigid platform to pull folded domains against. We speculate that these differences may have evolved due to the differing client pools these machines are expected to encounter.
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Affiliation(s)
- Aaron Snoberger
- Department of Biochemistry, West Virginia University School of MedicineMorgantown, WV, USA
| | - Raymond T Anderson
- Department of Biochemistry, West Virginia University School of MedicineMorgantown, WV, USA
| | - David M Smith
- Department of Biochemistry, West Virginia University School of MedicineMorgantown, WV, USA
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40
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Sysoeva TA. Assessing heterogeneity in oligomeric AAA+ machines. Cell Mol Life Sci 2017; 74:1001-1018. [PMID: 27669691 PMCID: PMC11107579 DOI: 10.1007/s00018-016-2374-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 09/13/2016] [Accepted: 09/19/2016] [Indexed: 10/20/2022]
Abstract
ATPases Associated with various cellular Activities (AAA+ ATPases) are molecular motors that use the energy of ATP binding and hydrolysis to remodel their target macromolecules. The majority of these ATPases form ring-shaped hexamers in which the active sites are located at the interfaces between neighboring subunits. Structural changes initiate in an active site and propagate to distant motor parts that interface and reshape the target macromolecules, thereby performing mechanical work. During the functioning cycle, the AAA+ motor transits through multiple distinct states. Ring architecture and placement of the catalytic sites at the intersubunit interfaces allow for a unique level of coordination among subunits of the motor. This in turn results in conformational differences among subunits and overall asymmetry of the motor ring as it functions. To date, a large amount of structural information has been gathered for different AAA+ motors, but even for the most characterized of them only a few structural states are known and the full mechanistic cycle cannot be yet reconstructed. Therefore, the first part of this work will provide a broad overview of what arrangements of AAA+ subunits have been structurally observed focusing on diversity of ATPase oligomeric ensembles and heterogeneity within the ensembles. The second part of this review will concentrate on methods that assess structural and functional heterogeneity among subunits of AAA+ motors, thus bringing us closer to understanding the mechanism of these fascinating molecular motors.
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Affiliation(s)
- Tatyana A Sysoeva
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA.
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41
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Tomko RJ. Proteasomes, caught in the act. Cell Res 2017; 27:307-308. [PMID: 28220774 DOI: 10.1038/cr.2017.22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Although energy-dependent protein destruction by the proteasome has been known for over 30 years, how this intricate molecular machine uses ATP to power protein degradation has remained very poorly understood. In a recently published paper, Ding et al. present a snapshot of the proteasome mid-catalysis, yielding new and unexpected insights into the catalytic mechanism of this ATP-powered multisubunit machine.
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Affiliation(s)
- Robert J Tomko
- Department of Biomedical Sciences, Florida State University College of Medicine, 1115 W. Call Street, Tallahassee, FL 32306, USA
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42
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High-resolution cryo-EM structure of the proteasome in complex with ADP-AlFx. Cell Res 2017; 27:373-385. [PMID: 28106073 DOI: 10.1038/cr.2017.12] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 12/05/2016] [Accepted: 12/23/2016] [Indexed: 12/12/2022] Open
Abstract
The 26S proteasome is an ATP-dependent dynamic 2.5 MDa protease that regulates numerous essential cellular functions through degradation of ubiquitinated substrates. Here we present a near-atomic-resolution cryo-EM map of the S. cerevisiae 26S proteasome in complex with ADP-AlFx. Our biochemical and structural data reveal that the proteasome-ADP-AlFx is in an activated state, displaying a distinct conformational configuration especially in the AAA-ATPase motor region. Noteworthy, this map demonstrates an asymmetric nucleotide binding pattern with four consecutive AAA-ATPase subunits bound with nucleotide. The remaining two subunits, Rpt2 and Rpt6, with empty or only partially occupied nucleotide pocket exhibit pronounced conformational changes in the AAA-ATPase ring, which may represent a collective result of allosteric cooperativity of all the AAA-ATPase subunits responding to ATP hydrolysis. This collective motion of Rpt2 and Rpt6 results in an elevation of their pore loops, which could play an important role in substrate processing of proteasome. Our data also imply that the nucleotide occupancy pattern could be related to the activation status of the complex. Moreover, the HbYX tail insertion may not be sufficient to maintain the gate opening of 20S core particle. Our results provide new insights into the mechanisms of nucleotide-driven allosteric cooperativity of the complex and of the substrate processing by the proteasome.
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Ibrahim Z, Martel A, Moulin M, Kim HS, Härtlein M, Franzetti B, Gabel F. Time-resolved neutron scattering provides new insight into protein substrate processing by a AAA+ unfoldase. Sci Rep 2017; 7:40948. [PMID: 28102317 PMCID: PMC5244417 DOI: 10.1038/srep40948] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 12/12/2016] [Indexed: 01/24/2023] Open
Abstract
We present a combination of small-angle neutron scattering, deuterium labelling and contrast variation, temperature activation and fluorescence spectroscopy as a novel approach to obtain time-resolved, structural data individually from macromolecular complexes and their substrates during active biochemical reactions. The approach allowed us to monitor the mechanical unfolding of a green fluorescent protein model substrate by the archaeal AAA+ PAN unfoldase on the sub-minute time scale. Concomitant with the unfolding of its substrate, the PAN complex underwent an energy-dependent transition from a relaxed to a contracted conformation, followed by a slower expansion to its initial state at the end of the reaction. The results support a model in which AAA ATPases unfold their substrates in a reversible power stroke mechanism involving several subunits and demonstrate the general utility of this time-resolved approach for studying the structural molecular kinetics of multiple protein remodelling complexes and their substrates on the sub-minute time scale.
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Affiliation(s)
- Ziad Ibrahim
- Université Grenoble Alpes, Institut de Biologie Structurale, 38044 Grenoble, France.,Centre National de la Recherche Scientifique, Institut de Biologie Structurale, 38044 Grenoble, France.,Centre à l'Energie Atomique et aux Energies Alternatives, Institut de Biologie Structurale, 38044 Grenoble, France.,Institut Laue-Langevin, 38042 Grenoble, France
| | - Anne Martel
- Institut Laue-Langevin, 38042 Grenoble, France
| | | | - Henry S Kim
- Université Grenoble Alpes, Institut de Biologie Structurale, 38044 Grenoble, France.,Centre National de la Recherche Scientifique, Institut de Biologie Structurale, 38044 Grenoble, France.,Centre à l'Energie Atomique et aux Energies Alternatives, Institut de Biologie Structurale, 38044 Grenoble, France
| | | | - Bruno Franzetti
- Université Grenoble Alpes, Institut de Biologie Structurale, 38044 Grenoble, France.,Centre National de la Recherche Scientifique, Institut de Biologie Structurale, 38044 Grenoble, France.,Centre à l'Energie Atomique et aux Energies Alternatives, Institut de Biologie Structurale, 38044 Grenoble, France
| | - Frank Gabel
- Université Grenoble Alpes, Institut de Biologie Structurale, 38044 Grenoble, France.,Centre National de la Recherche Scientifique, Institut de Biologie Structurale, 38044 Grenoble, France.,Centre à l'Energie Atomique et aux Energies Alternatives, Institut de Biologie Structurale, 38044 Grenoble, France.,Institut Laue-Langevin, 38042 Grenoble, France
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Bacterial Proteasomes: Mechanistic and Functional Insights. Microbiol Mol Biol Rev 2016; 81:81/1/e00036-16. [PMID: 27974513 DOI: 10.1128/mmbr.00036-16] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Regulated proteolysis is essential for the normal physiology of all organisms. While all eukaryotes and archaea use proteasomes for protein degradation, only certain orders of bacteria have proteasomes, whose functions are likely as diverse as the species that use them. In this review, we discuss the most recent developments in the understanding of how proteins are targeted to proteasomes for degradation, including ATP-dependent and -independent mechanisms, and the roles of proteasome-dependent degradation in protein quality control and the regulation of cellular physiology. Furthermore, we explore newly established functions of proteasome system accessory factors that function independently of proteolysis.
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Mou L, Cui T, Liu W, Zhang H, Cai Z, Lu S, Gao G. Microsecond molecular dynamics simulations provide insight into the ATP-competitive inhibitor-induced allosteric protection of Akt kinase phosphorylation. Chem Biol Drug Des 2016; 89:723-731. [PMID: 27797456 DOI: 10.1111/cbdd.12895] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 10/02/2016] [Accepted: 10/25/2016] [Indexed: 11/28/2022]
Abstract
Akt is a serine/threonine protein kinase, a critical mediator of growth factor-induced survival in key cellular pathways. Allosteric signaling between protein intramolecular domains requires long-range communication mediated by hotspot residues, often triggered by ligand binding. Here, based on extensive 3 μs explicit solvent molecular dynamics (MD) simulations of Akt1 kinase domain in the unbound (apo) and ATP-competitive inhibitor, GDC-0068-bound states, we propose a molecular mechanism for allosteric regulation of Akt1 kinase phosphorylation by GDC-0068 binding to the ATP-binding site. MD simulations revealed that the apo Akt1 is flexible with two disengaged N- and C-lobes, equilibrated between the open and closed conformations. GDC-0068 occupancy of the ATP-binding site shifts the conformational equilibrium of Akt1 from the open conformation toward the closed conformation and stabilizes the closed state. This effect enables allosteric signal propagation from the GDC-0068 to the phosphorylated T308 (pT308) in the activation loop and restrains phosphatase access to pT308, thereby protecting the pT308 in the GDC-0068-bound Akt1. Importantly, functional hotspots involved in the allosteric communication from the GDC-0068 to the pT308 are identified. Our analysis of GDC-0068-induced allosteric protection of Akt kinase phosphorylation yields important new insights into the molecular mechanism of allosteric regulation of Akt kinase activity.
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Affiliation(s)
- Linkai Mou
- Department of Urology, Affiliated Hospital of Weifang Medical University, Weifang, Shandong, China
| | - Tongwei Cui
- Department of Urology, Affiliated Hospital of Weifang Medical University, Weifang, Shandong, China
| | - Weiguang Liu
- Department of Urology, Affiliated Hospital of Weifang Medical University, Weifang, Shandong, China
| | - Hong Zhang
- Department of Urology, Affiliated Hospital of Weifang Medical University, Weifang, Shandong, China
| | - Zhanxiu Cai
- Department of Electrical and Computer Engineering, College of Bioscience and Technology, Weifang Medical University, Weifang, Shandong, China
| | - Shaoyong Lu
- Department of Pathophysiology, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Guojun Gao
- Department of Urology, Affiliated Hospital of Weifang Medical University, Weifang, Shandong, China
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Wehmer M, Sakata E. Recent advances in the structural biology of the 26S proteasome. Int J Biochem Cell Biol 2016; 79:437-442. [PMID: 27498189 DOI: 10.1016/j.biocel.2016.08.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 08/02/2016] [Accepted: 08/03/2016] [Indexed: 11/29/2022]
Abstract
There is growing appreciation for the fundamental role of structural dynamics in the function of macromolecules. In particular, the 26S proteasome, responsible for selective protein degradation in an ATP dependent manner, exhibits dynamic conformational changes that enable substrate processing. Recent cryo-electron microscopy (cryo-EM) work has revealed the conformational dynamics of the 26S proteasome and established the function of the different conformational states. Technological advances such as direct electron detectors and image processing algorithms allowed resolving the structure of the proteasome at atomic resolution. Here we will review those studies and discuss their contribution to our understanding of proteasome function.
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Affiliation(s)
- Marc Wehmer
- Department of Molecular Structural Biology, Max Planck institute of Biochemistry, 82152, Martinsried, Germany
| | - Eri Sakata
- Department of Molecular Structural Biology, Max Planck institute of Biochemistry, 82152, Martinsried, Germany.
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Open-gate mutants of the mammalian proteasome show enhanced ubiquitin-conjugate degradation. Nat Commun 2016; 7:10963. [PMID: 26957043 PMCID: PMC4786872 DOI: 10.1038/ncomms10963] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 02/04/2016] [Indexed: 12/20/2022] Open
Abstract
When in the closed form, the substrate translocation channel of the proteasome core
particle (CP) is blocked by the convergent N termini of α-subunits. To
probe the role of channel gating in mammalian proteasomes, we deleted the N-terminal
tail of α3; the resulting α3ΔN proteasomes are intact
but hyperactive in the hydrolysis of fluorogenic peptide substrates and the
degradation of polyubiquitinated proteins. Cells expressing the hyperactive
proteasomes show markedly elevated degradation of many established proteasome
substrates and resistance to oxidative stress. Multiplexed quantitative proteomics
revealed ∼200 proteins with reduced levels in the mutant cells. Potentially
toxic proteins such as tau exhibit reduced accumulation and aggregate formation.
These data demonstrate that the CP gate is a key negative regulator of proteasome
function in mammals, and that opening the CP gate may be an effective strategy to
increase proteasome activity and reduce levels of toxic proteins in cells. The proteasome plays a key role in proteostasis by mediating the
degradation of ubiquitinated substrates. Here the authors show that an open-gate mutant
of the proteasome is hyperactive towards a subset of substrates and can effectively
delay the accumulation of toxic protein aggregates.
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