1
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Nath S. Phosphorus Chemistry at the Roots of Bioenergetics: Ligand Permutation as the Molecular Basis of the Mechanism of ATP Synthesis/Hydrolysis by F OF 1-ATP Synthase. Molecules 2023; 28:7486. [PMID: 38005208 PMCID: PMC10673332 DOI: 10.3390/molecules28227486] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 11/04/2023] [Accepted: 11/06/2023] [Indexed: 11/26/2023] Open
Abstract
The integration of phosphorus chemistry with the mechanism of ATP synthesis/hydrolysis requires dynamical information during ATP turnover and catalysis. Oxygen exchange reactions occurring at β-catalytic sites of the FOF1-ATP synthase/F1-ATPase imprint a unique record of molecular events during the catalytic cycle of ATP synthesis/hydrolysis. They have been shown to provide valuable time-resolved information on enzyme catalysis during ATP synthesis and ATP hydrolysis. The present work conducts new experiments on oxygen exchange catalyzed by submitochondrial particles designed to (i) measure the relative rates of Pi-ATP, Pi-HOH, and ATP-HOH isotope exchanges; (ii) probe the effect of ADP removal on the extent of inhibition of the exchanges, and (iii) test their uncoupler sensitivity/resistance. The objectives have been realized based on new experiments on submitochondrial particles, which show that both the Pi-HOH and ATP-HOH exchanges occur at a considerably higher rate relative to the Pi-ATP exchange, an observation that cannot be explained by previous mechanisms. A unifying explanation of the kinetic data that rationalizes these observations is given. The experimental results in (ii) show that ADP removal does not inhibit the intermediate Pi-HOH exchange when ATP and submitochondrial particles are incubated, and that the nucleotide requirement of the intermediate Pi-HOH exchange is adequately met by ATP, but not by ADP. These results contradicts the central postulate in Boyer's binding change mechanism of reversible catalysis at a F1 catalytic site with Keq~1 that predicts an absolute requirement of ADP for the occurrence of the Pi-HOH exchange. The prominent intermediate Pi-HOH exchange occurring under hydrolytic conditions is shown to be best explained by Nath's torsional mechanism of energy transduction and ATP synthesis/hydrolysis, which postulates an essentially irreversible cleavage of ATP by mitochondria/particles, independent from a reversible formation of ATP from ADP and Pi. The explanation within the torsional mechanism is also shown to rationalize the relative insensitivity of the intermediate Pi-HOH exchange to uncouplers observed in the experiments in (iii) compared to the Pi-ATP and ATP-HOH exchanges. This is shown to lead to new concepts and perspectives based on ligand displacement/substitution and ligand permutation for the elucidation of the oxygen exchange reactions within the framework of fundamental phosphorus chemistry. Fast mechanisms that realize the rotation/twist, tilt, permutation and switch of ligands, as well as inversion at the γ-phosphorus synchronously and simultaneously and in a concerted manner, have been proposed, and their stereochemical consequences have been analyzed. These considerations take us beyond the binding change mechanism of ATP synthesis/hydrolysis in bioenergetics.
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Affiliation(s)
- Sunil Nath
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India; or
- Institute of Molecular Psychiatry, Rheinische-Friedrichs-Wilhelm Universität Bonn, D-53127 Bonn, Germany
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2
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Nath S. Elucidating Events within the Black Box of Enzyme Catalysis in Energy Metabolism: Insights into the Molecular Mechanism of ATP Hydrolysis by F 1-ATPase. Biomolecules 2023; 13:1596. [PMID: 38002278 PMCID: PMC10669602 DOI: 10.3390/biom13111596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Revised: 10/23/2023] [Accepted: 10/26/2023] [Indexed: 11/26/2023] Open
Abstract
Oxygen exchange reactions occurring at β-catalytic sites of the FOF1-ATP synthase/F1-ATPase imprint a unique record of molecular events during the catalytic cycle of ATP synthesis/hydrolysis. This work presents a new theory of oxygen exchange and tests it on oxygen exchange data recorded on ATP hydrolysis by mitochondrial F1-ATPase (MF1). The apparent rate constant of oxygen exchange governing the intermediate Pi-HOH exchange accompanying ATP hydrolysis is determined by kinetic analysis over a ~50,000-fold range of substrate ATP concentration (0.1-5000 μM) and a corresponding ~200-fold range of reaction velocity (3.5-650 [moles of Pi/{moles of F1-ATPase}-1 s-1]). Isotopomer distributions of [18O]Pi species containing 0, 1, 2, and 3 labeled oxygen atoms predicted by the theory have been quantified and shown to be in perfect agreement with the experimental distributions over the entire range of medium ATP concentrations without employing adjustable parameters. A novel molecular mechanism of steady-state multisite ATP hydrolysis by the F1-ATPase has been proposed. Our results show that steady-state ATP hydrolysis by F1-ATPase occurs with all three sites occupied by Mg-nucleotide. The various implications arising from models of energy coupling in ATP synthesis/hydrolysis by the ATP synthase/F1-ATPase have been discussed. Current models of ATP hydrolysis by F1-ATPase, including those postulated from single-molecule data, are shown to be effectively bisite models that contradict the data. The trisite catalysis formulated by Nath's torsional mechanism of energy transduction and ATP synthesis/hydrolysis since its first appearance 25 years ago is shown to be in better accord with the experimental record. The total biochemical information on ATP hydrolysis is integrated into a consistent model by the torsional mechanism of ATP synthesis/hydrolysis and shown to elucidate the elementary chemical and mechanical events within the black box of enzyme catalysis in energy metabolism by F1-ATPase.
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Affiliation(s)
- Sunil Nath
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India; or
- Institute of Molecular Psychiatry, Rheinische-Friedrichs-Wilhelm Universität Bonn, D–53127 Bonn, Germany
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3
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Mazuecos L, Alberdi P, Hernández-Jarguín A, Contreras M, Villar M, Cabezas-Cruz A, Simo L, González-García A, Díaz-Sánchez S, Neelakanta G, Bonnet SI, Fikrig E, de la Fuente J. Frankenbacteriosis targeting interactions between pathogen and symbiont to control infection in the tick vector. iScience 2023; 26:106697. [PMID: 37168564 PMCID: PMC10165458 DOI: 10.1016/j.isci.2023.106697] [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: 11/15/2022] [Revised: 01/23/2023] [Accepted: 04/13/2023] [Indexed: 05/13/2023] Open
Abstract
Tick microbiota can be targeted for the control of tick-borne diseases such as human granulocytic anaplasmosis (HGA) caused by model pathogen, Anaplasma phagocytophilum. Frankenbacteriosis is inspired by Frankenstein and defined here as paratransgenesis of tick symbiotic/commensal bacteria to mimic and compete with tick-borne pathogens. Interactions between A. phagocytophilum and symbiotic Sphingomonas identified by metaproteomics analysis in Ixodes scapularis midgut showed competition between both bacteria. Consequently, Sphingomonas was selected for frankenbacteriosis for the control of A. phagocytophilum infection and transmission. The results showed that Franken Sphingomonas producing A. phagocytophilum major surface protein 4 (MSP4) mimic pathogen and reduce infection in ticks by competition and interaction with cell receptor components of infection. Franken Sphingomonas-MSP4 transovarial and trans-stadial transmission suggests that tick larvae with genetically modified Franken Sphingomonas-MSP4 could be produced in the laboratory and released in the field to compete and replace the wildtype populations with associated reduction in pathogen infection/transmission and HGA disease risks.
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Affiliation(s)
- Lorena Mazuecos
- SaBio. Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo 12, 13005 Ciudad Real, Spain
| | - Pilar Alberdi
- SaBio. Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo 12, 13005 Ciudad Real, Spain
| | - Angélica Hernández-Jarguín
- SaBio. Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo 12, 13005 Ciudad Real, Spain
| | - Marinela Contreras
- SaBio. Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo 12, 13005 Ciudad Real, Spain
| | - Margarita Villar
- SaBio. Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo 12, 13005 Ciudad Real, Spain
| | - Alejandro Cabezas-Cruz
- ANSES, INRAE, Ecole Nationale Vétérinaire d’Alfort, UMR BIPAR, Laboratoire de Santé Animale, 94700 Maisons-Alfort, France
| | - Ladislav Simo
- ANSES, INRAE, Ecole Nationale Vétérinaire d’Alfort, UMR BIPAR, Laboratoire de Santé Animale, 94700 Maisons-Alfort, France
| | - Almudena González-García
- SaBio. Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo 12, 13005 Ciudad Real, Spain
| | - Sandra Díaz-Sánchez
- SaBio. Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo 12, 13005 Ciudad Real, Spain
| | - Girish Neelakanta
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996, USA
- Department of Biological Sciences, Old Dominion University, Norfolk, VA 23529, USA
| | - Sarah I. Bonnet
- Functional Genetics of Infectious Diseases Unit, Institut Pasteur, CNRS UMR 2000, Université de Paris, 75015 Paris, France
- Animal Health Department, INRAE, 37380 Nouzilly, France
| | - Erol Fikrig
- Section of Infectious Diseases, Yale University School of Medicine, New Haven, CT 208022, USA
| | - José de la Fuente
- SaBio. Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo 12, 13005 Ciudad Real, Spain
- Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA
- Corresponding author
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Kobayashi R, Ueno H, Okazaki KI, Noji H. Molecular mechanism on forcible ejection of ATPase inhibitory factor 1 from mitochondrial ATP synthase. Nat Commun 2023; 14:1682. [PMID: 37002198 PMCID: PMC10066207 DOI: 10.1038/s41467-023-37182-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 03/06/2023] [Indexed: 04/03/2023] Open
Abstract
IF1 is a natural inhibitor protein for mitochondrial FoF1 ATP synthase that blocks catalysis and rotation of the F1 by deeply inserting its N-terminal helices into F1. A unique feature of IF1 is condition-dependent inhibition; although IF1 inhibits ATP hydrolysis by F1, IF1 inhibition is relieved under ATP synthesis conditions. To elucidate this condition-dependent inhibition mechanism, we have performed single-molecule manipulation experiments on IF1-inhibited bovine mitochondrial F1 (bMF1). The results show that IF1-inhibited F1 is efficiently activated only when F1 is rotated in the clockwise (ATP synthesis) direction, but not in the counterclockwise direction. The observed rotational-direction-dependent activation explains the condition-dependent mechanism of IF1 inhibition. Investigation of mutant IF1 with N-terminal truncations shows that the interaction with the γ subunit at the N-terminal regions is crucial for rotational-direction-dependent ejection, and the middle long helix is responsible for the inhibition of F1.
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Affiliation(s)
- Ryohei Kobayashi
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8656, Japan
- Research Center for Computational Science, Institute for Molecular Science, Okazaki, Aichi, 444-8585, Japan
| | - Hiroshi Ueno
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Kei-Ichi Okazaki
- Research Center for Computational Science, Institute for Molecular Science, Okazaki, Aichi, 444-8585, Japan
- The Graduate University for Advanced Studies, SOKENDAI, Okazaki, Aichi, 444-8585, Japan
| | - Hiroyuki Noji
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8656, Japan.
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5
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Sielaff H, Dienerowitz F, Dienerowitz M. Single-molecule FRET combined with electrokinetic trapping reveals real-time enzyme kinetics of individual F-ATP synthases. NANOSCALE 2022; 14:2327-2336. [PMID: 35084006 DOI: 10.1039/d1nr05754e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Single-molecule Förster resonance energy transfer (smFRET) is a key technique to observe conformational changes in molecular motors and to access the details of single-molecule static and dynamic disorder during catalytic processes. However, studying freely diffusing molecules in solution is limited to a few tens of milliseconds, while surface attachment often bears the risk to restrict their natural motion. In this paper we combine smFRET and electrokinetic trapping (ABEL trap) to non-invasively hold single FOF1-ATP synthases for up to 3 s within the detection volume, thereby extending the observation time by a factor of 10 as compared to Brownian diffusion without surface attachment. In addition, we are able to monitor complete reaction cycles and to selectively trap active molecules based on their smFRET signal, thus speeding up the data acquisition process. We demonstrate the capability of our method to study the dynamics of single molecules by recording the ATP-hydrolysis driven rotation of individual FOF1-ATP synthase molecules over numerous reaction cycles and extract their kinetic rates. We argue that our method is not limited to motor proteins. Instead, it can be applied to monitor conformational changes with millisecond time resolution for a wide range of enzymes, thereby making it a versatile tool for studying protein dynamics.
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Affiliation(s)
- Hendrik Sielaff
- Department of Chemistry, Centre for BioImaging Sciences, National University of Singapore, 14 Science Drive 4, 117557 Singapore, Singapore
| | - Frank Dienerowitz
- Ernst-Abbe-Hochschule Jena, University of Applied Sciences, Carl-Zeiss-Promenade 2, 07745 Jena, Germany
| | - Maria Dienerowitz
- Single-Molecule Microscopy Group, Universitätsklinikum Jena, Nonnenplan 2-4, 07743 Jena, Germany.
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6
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Mehta R, Singh J, Nath S. Time-Resolved Oxygen Exchange Measurements Offer Novel Mechanistic Insights into Enzyme-Catalyzed ATP Synthesis during Photophosphorylation. J Phys Chem B 2020; 124:5139-5148. [PMID: 32484674 DOI: 10.1021/acs.jpcb.0c03505] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Techniques to probe molecular mechanistic events occurring at a single catalytic site of multi-subunit enzymes in real time are few and are still under development. Here time-resolved information is extracted from measurements of the extensive oxygen exchange that occurs at an intermediate stage of adenosine triphosphate (ATP) synthesis during photophosphorylation by chloroplast thylakoids. A stochastic process-based approach for modeling exchange reactions is formulated that provides a physical basis for the kinetic theory. Compatible with the assumptions made in such a model of randomness, the formulation is shown to lead to a Poisson-type theory that enables kinetic analysis of oxygen-exchange data and offers novel physical insights. Parameters such as the apparent rate constant of exchange and the average lifetime of the exchanging intermediates during the synthesis of ATP by the chloroplast F1FO-ATP synthase have been determined over a 5000-fold range of ADP concentration. Experimental isotopomer distributions of [18O]ATP at high (0.5 mM), intermediate (10 μM), and low (0.2 μM) ADP concentrations have been quantified and compared to expected distributions from the theory. The observed distributions are shown to closely match the predicted distributions. A wealth of novel mechanistic insights such as the number of sites/pathways of oxygen exchange, the order of substrate binding steps at the enzyme catalytic site, and regulation of the process of energy coupling have been deduced, and the results are interpreted with the help of available high-resolution X-ray structures. The various biological implications for models of energy coupling have been discussed. Permutation of oxygen ligands about the phosphorus center is proposed as a possible and general but not well-recognized mechanism for oxygen exchange that is consistent with the principal results of this work, and several suggestions for future research are offered.
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Affiliation(s)
- Ritu Mehta
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Jitendra Singh
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Sunil Nath
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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7
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Sielaff H, Yanagisawa S, Frasch WD, Junge W, Börsch M. Structural Asymmetry and Kinetic Limping of Single Rotary F-ATP Synthases. Molecules 2019; 24:E504. [PMID: 30704145 PMCID: PMC6384691 DOI: 10.3390/molecules24030504] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 01/23/2019] [Accepted: 01/29/2019] [Indexed: 12/12/2022] Open
Abstract
F-ATP synthases use proton flow through the FO domain to synthesize ATP in the F₁ domain. In Escherichia coli, the enzyme consists of rotor subunits γεc10 and stator subunits (αβ)₃δab₂. Subunits c10 or (αβ)₃ alone are rotationally symmetric. However, symmetry is broken by the b₂ homodimer, which together with subunit δa, forms a single eccentric stalk connecting the membrane embedded FO domain with the soluble F₁ domain, and the central rotating and curved stalk composed of subunit γε. Although each of the three catalytic binding sites in (αβ)₃ catalyzes the same set of partial reactions in the time average, they might not be fully equivalent at any moment, because the structural symmetry is broken by contact with b₂δ in F₁ and with b₂a in FO. We monitored the enzyme's rotary progression during ATP hydrolysis by three single-molecule techniques: fluorescence video-microscopy with attached actin filaments, Förster resonance energy transfer between pairs of fluorescence probes, and a polarization assay using gold nanorods. We found that one dwell in the three-stepped rotary progression lasting longer than the other two by a factor of up to 1.6. This effect of the structural asymmetry is small due to the internal elastic coupling.
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Affiliation(s)
- Hendrik Sielaff
- Single-Molecule Microscopy Group, Jena University Hospital, Friedrich Schiller University, 07743 Jena, Germany.
| | - Seiga Yanagisawa
- School of Life Sciences, Arizona State University, Tempe, Arizona, AZ 85287, USA.
| | - Wayne D Frasch
- School of Life Sciences, Arizona State University, Tempe, Arizona, AZ 85287, USA.
| | - Wolfgang Junge
- Department of Biology & Chemistry, University of Osnabrück, 49076 Osnabrück, Germany.
| | - Michael Börsch
- Single-Molecule Microscopy Group, Jena University Hospital, Friedrich Schiller University, 07743 Jena, Germany.
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8
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Manoj KM. Aerobic Respiration: Criticism of the Proton-centric Explanation Involving Rotary Adenosine Triphosphate Synthesis, Chemiosmosis Principle, Proton Pumps and Electron Transport Chain. BIOCHEMISTRY INSIGHTS 2018; 11:1178626418818442. [PMID: 30643418 PMCID: PMC6311555 DOI: 10.1177/1178626418818442] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 11/20/2018] [Indexed: 12/17/2022]
Abstract
The acclaimed explanation for mitochondrial oxidative phosphorylation (mOxPhos, or cellular respiration) is a deterministic proton-centric scheme involving four components: Rotary adenosine triphosphate (ATP)-synthesis, Chemiosmosis principle, Proton pumps, and Electron transport chain (abbreviated as RCPE hypothesis). Within this write-up, the RCPE scheme is critically analyzed with respect to mitochondrial architecture, proteins’ distribution, structure-function correlations and their interactive dynamics, overall reaction chemistry, kinetics, thermodynamics, evolutionary logic, and so on. It is found that the RCPE proposal fails to explain key physiological aspects of mOxPhos in several specific issues and also in holistic perspectives. Therefore, it is imperative to look for new explanations for mOxPhos.
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9
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Murcia Rios A, Vahidi S, Dunn SD, Konermann L. Evidence for a Partially Stalled γ Rotor in F 1-ATPase from Hydrogen-Deuterium Exchange Experiments and Molecular Dynamics Simulations. J Am Chem Soc 2018; 140:14860-14869. [PMID: 30339028 DOI: 10.1021/jacs.8b08692] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
F1-ATPase uses ATP hydrolysis to drive rotation of the γ subunit. The γ C-terminal helix constitutes the rotor tip that is seated in an apical bearing formed by α3β3. It remains uncertain to what extent the γ conformation during rotation differs from that seen in rigid crystal structures. Existing models assume that the entire γ subunit participates in every rotation. Here we interrogated E. coli F1-ATPase by hydrogen-deuterium exchange (HDX) mass spectrometry. Rotation of γ caused greatly enhanced deuteration in the γ C-terminal helix. The HDX kinetics implied that most F1 complexes operate with an intact rotor at any given time, but that the rotor tip is prone to occasional unfolding. A molecular dynamics (MD) strategy was developed to model the off-axis forces acting on γ. MD runs showed stalling of the rotor tip and unfolding of the γ C-terminal helix. MD-predicted H-bond opening events coincided with experimental HDX patterns. Our data suggest that in vitro operation of F1-ATPase is associated with significant rotational resistance in the apical bearing. These conditions cause the γ C-terminal helix to get "stuck" (and unfold) sporadically while the remainder of γ continues to rotate. This scenario contrasts the traditional "greasy bearing" model that envisions smooth rotation of the γ C-terminal helix. The fragility of the apical rotor tip in F1-ATPase is attributed to the absence of a c10 ring that stabilizes the rotation axis in intact FoF1. Overall, the MD/HDX strategy introduced here appears well suited for interrogating the inner workings of molecular motors.
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Affiliation(s)
- Angela Murcia Rios
- Departments of Chemistry and Biochemistry , The University of Western Ontario , London , Ontario N6A 5B7 , Canada
| | - Siavash Vahidi
- Departments of Chemistry and Biochemistry , The University of Western Ontario , London , Ontario N6A 5B7 , Canada
| | - Stanley D Dunn
- Departments of Chemistry and Biochemistry , The University of Western Ontario , London , Ontario N6A 5B7 , Canada
| | - Lars Konermann
- Departments of Chemistry and Biochemistry , The University of Western Ontario , London , Ontario N6A 5B7 , Canada
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10
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Starke I, Glick GD, Börsch M. Visualizing Mitochondrial F oF 1-ATP Synthase as the Target of the Immunomodulatory Drug Bz-423. Front Physiol 2018; 9:803. [PMID: 30022951 PMCID: PMC6039829 DOI: 10.3389/fphys.2018.00803] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 06/07/2018] [Indexed: 01/17/2023] Open
Abstract
Targeting the mitochondrial enzyme FoF1-ATP synthase and modulating its catalytic activities with small molecules is a promising new approach for treatment of autoimmune diseases. The immunomodulatory compound Bz-423 is such a drug that binds to subunit OSCP of the mitochondrial FoF1-ATP synthase and induces apoptosis via increased reactive oxygen production in coupled, actively respiring mitochondria. Here, we review the experimental progress to reveal the binding of Bz-423 to the mitochondrial target and discuss how subunit rotation of FoF1-ATP synthase is affected by Bz-423. Briefly, we report how Förster resonance energy transfer can be employed to colocalize the enzyme and the fluorescently tagged Bz-423 within the mitochondria of living cells with nanometer resolution.
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Affiliation(s)
- Ilka Starke
- Single-Molecule Microscopy Group, Jena University Hospital, Friedrich Schiller University, Jena, Germany.,Institute for Physical Chemistry, Albert Ludwigs University of Freiburg, Freiburg, Germany
| | - Gary D Glick
- Department of Chemistry, University of Michigan, Ann Arbor, MI, United States
| | - Michael Börsch
- Single-Molecule Microscopy Group, Jena University Hospital, Friedrich Schiller University, Jena, Germany.,Abbe Center of Photonics, Friedrich Schiller University, Jena, Germany
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11
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Sielaff H, Duncan TM, Börsch M. The regulatory subunit ε in Escherichia coli F OF 1-ATP synthase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:775-788. [PMID: 29932911 DOI: 10.1016/j.bbabio.2018.06.013] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 06/13/2018] [Accepted: 06/14/2018] [Indexed: 11/16/2022]
Abstract
F-type ATP synthases are extraordinary multisubunit proteins that operate as nanomotors. The Escherichia coli (E. coli) enzyme uses the proton motive force (pmf) across the bacterial plasma membrane to drive rotation of the central rotor subunits within a stator subunit complex. Through this mechanical rotation, the rotor coordinates three nucleotide binding sites that sequentially catalyze the synthesis of ATP. Moreover, the enzyme can hydrolyze ATP to turn the rotor in the opposite direction and generate pmf. The direction of net catalysis, i.e. synthesis or hydrolysis of ATP, depends on the cell's bioenergetic conditions. Different control mechanisms have been found for ATP synthases in mitochondria, chloroplasts and bacteria. This review discusses the auto-inhibitory behavior of subunit ε found in FOF1-ATP synthases of many bacteria. We focus on E. coli FOF1-ATP synthase, with insights into the regulatory mechanism of subunit ε arising from structural and biochemical studies complemented by single-molecule microscopy experiments.
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Affiliation(s)
- Hendrik Sielaff
- Single-Molecule Microscopy Group, Jena University Hospital, Friedrich Schiller University, Jena, Germany
| | - Thomas M Duncan
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Michael Börsch
- Single-Molecule Microscopy Group, Jena University Hospital, Friedrich Schiller University, Jena, Germany.
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12
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Sun X, Morrell TE, Yang H. Extraction of Protein Conformational Modes from Distance Distributions Using Structurally Imputed Bayesian Data Augmentation. J Phys Chem B 2016; 120:10469-10482. [PMID: 27642672 DOI: 10.1021/acs.jpcb.6b07767] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Protein conformational changes are known to play important roles in assorted biochemical and biological processes. Driven by thermal motions of surrounding solvent molecules, such a structural remodeling often occurs stochastically. Yet, regardless of how random the conformational reconfiguration may appear, it could in principle be described by a linear combination of a set of orthogonal modes which, in turn, are contained in the intramolecular distance distributions. The central challenge is how to obtain the distribution. This contribution proposes a Bayesian data-augmentation scheme to extract the predominant modes from only few distance distributions, be they from computational sampling or directly from experiments such as single-molecule Förster-type resonance energy transfer (smFRET). The inference of the complete protein structure from insufficient data was recognized as isomorphic to the missing-data problem in Bayesian statistical learning. Using smFRET data as an example, the missing coordinates were deduced, given protein structural constraints and multiple but limited number of smFRET distances; the Boltzmann weighing of each inferred protein structure was then evaluated using computational modeling to numerically construct the posterior density for the global protein conformation. The conformational modes were then determined from the iteratively converged overall conformational distribution using principal component analysis. Two examples were presented to illustrate these basic ideas as well as their practical implementation. The scheme described herein was based on the theory behind the powerful Tanner-Wang algorithm that guarantees convergence to the true posterior density. However, instead of assuming a mathematical model to calculate the likelihood as in conventional statistical inference, here the protein structure was treated as a statistical parameter and was imputed from the numerical likelihood function based on structural information, a probability model-free method. The framework put forth here is anticipated to be generally applicable, offering a new way to articulate protein conformational changes in a quantifiable manner.
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Affiliation(s)
- Xun Sun
- Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
| | - Thomas E Morrell
- Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
| | - Haw Yang
- Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
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13
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Single molecule fluorescence spectroscopy for quantitative biological applications. QUANTITATIVE BIOLOGY 2016. [DOI: 10.1007/s40484-016-0083-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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14
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Load-dependent destabilization of the γ-rotor shaft in FOF1 ATP synthase revealed by hydrogen/deuterium-exchange mass spectrometry. Proc Natl Acad Sci U S A 2016; 113:2412-7. [PMID: 26884184 DOI: 10.1073/pnas.1520464113] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
FoF1 is a membrane-bound molecular motor that uses proton-motive force (PMF) to drive the synthesis of ATP from ADP and Pi. Reverse operation generates PMF via ATP hydrolysis. Catalysis in either direction involves rotation of the γε shaft that connects the α3β3 head and the membrane-anchored cn ring. X-ray crystallography and other techniques have provided insights into the structure and function of FoF1 subcomplexes. However, interrogating the conformational dynamics of intact membrane-bound FoF1 during rotational catalysis has proven to be difficult. Here, we use hydrogen/deuterium exchange mass spectrometry to probe the inner workings of FoF1 in its natural membrane-bound state. A pronounced destabilization of the γ C-terminal helix during hydrolysis-driven rotation was observed. This behavior is attributed to torsional stress in γ, arising from γ⋅⋅⋅α3β3 interactions that cause resistance during γ rotation within the apical bearing. Intriguingly, we find that destabilization of γ occurs only when FoF1 operates against a PMF-induced torque; the effect disappears when PMF is eliminated by an uncoupler. This behavior resembles the properties of automotive engines, where bearings inflict greater forces on the crankshaft when operated under load than during idling.
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15
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Nesci S, Trombetti F, Ventrella V, Pagliarani A. Opposite rotation directions in the synthesis and hydrolysis of ATP by the ATP synthase: hints from a subunit asymmetry. J Membr Biol 2015; 248:163-9. [PMID: 25655107 DOI: 10.1007/s00232-014-9760-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 11/18/2014] [Indexed: 11/25/2022]
Abstract
The ATP synthase can be imagined as a reversible H(+)-translocating channel embedded in the membrane, FO portion, coupled to a protruding catalytic portion, F1. Under physiological conditions the F1FO complex synthesizes ATP by exploiting the transmembrane electrochemical gradient of protons and their downhill movement. Alternatively, under other patho-physiological conditions it exploits ATP hydrolysis to energize the membrane by uphill pumping protons. The reversibility of the mechanism is guaranteed by the structural coupling between the hydrophilic F1 and the hydrophobic FO. Which of the two opposite processes wins in the energy-transducing membrane complex depends on the thermodynamic balance between the protonmotive force (Δp) and the phosphorylation potential of ATP (ΔG P). Accordingly, while Δp prevalence drives ATP synthesis by translocating protons from the membrane P-side to the N-side and generating anticlockwise torque rotation (viewed from the matrix), ΔG P drives ATP hydrolysis by chemomechanical coupling of FO to F1 with clockwise torque. The direction of rotation is the same in all the ATP synthases, due to the conserved steric arrangement of the chiral a subunit of FO. The ability of this coupled bi-functional complex to produce opposite rotations in ATP synthesis and hydrolysis is explained on the basis of the a subunit asymmetry.
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Affiliation(s)
- Salvatore Nesci
- Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy
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16
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Calculation and visualization of atomistic mechanical stresses in nanomaterials and biomolecules. PLoS One 2014; 9:e113119. [PMID: 25503996 PMCID: PMC4263534 DOI: 10.1371/journal.pone.0113119] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 10/23/2014] [Indexed: 11/19/2022] Open
Abstract
Many biomolecules have machine-like functions, and accordingly are discussed in terms of mechanical properties like force and motion. However, the concept of stress, a mechanical property that is of fundamental importance in the study of macroscopic mechanics, is not commonly applied in the biomolecular context. We anticipate that microscopical stress analyses of biomolecules and nanomaterials will provide useful mechanistic insights and help guide molecular design. To enable such applications, we have developed Calculator of Atomistic Mechanical Stress (CAMS), an open-source software package for computing atomic resolution stresses from molecular dynamics (MD) simulations. The software also enables decomposition of stress into contributions from bonded, nonbonded and Generalized Born potential terms. CAMS reads GROMACS topology and trajectory files, which are easily generated from AMBER files as well; and time-varying stresses may be animated and visualized in the VMD viewer. Here, we review relevant theory and present illustrative applications.
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17
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Fillingame RH, Steed PR. Half channels mediating H+ transport and the mechanism of gating in the Fo sector of Escherichia coli F1Fo ATP synthase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1063-8. [DOI: 10.1016/j.bbabio.2014.03.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 03/06/2014] [Accepted: 03/10/2014] [Indexed: 11/29/2022]
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18
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Guix M, Mayorga-Martinez CC, Merkoçi A. Nano/micromotors in (bio)chemical science applications. Chem Rev 2014; 114:6285-322. [PMID: 24827167 DOI: 10.1021/cr400273r] [Citation(s) in RCA: 320] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Maria Guix
- Nanobioelectronics & Biosensors Group, Institut Català de Nanosciencia i Nanotecnologia (ICN2), UAB Campus, 08193 Bellaterra, Barcelona, Spain
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19
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Antoniel M, Giorgio V, Fogolari F, Glick GD, Bernardi P, Lippe G. The oligomycin-sensitivity conferring protein of mitochondrial ATP synthase: emerging new roles in mitochondrial pathophysiology. Int J Mol Sci 2014; 15:7513-36. [PMID: 24786291 PMCID: PMC4057687 DOI: 10.3390/ijms15057513] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2014] [Revised: 04/18/2014] [Accepted: 04/21/2014] [Indexed: 01/08/2023] Open
Abstract
The oligomycin-sensitivity conferring protein (OSCP) of the mitochondrial F(O)F1 ATP synthase has long been recognized to be essential for the coupling of proton transport to ATP synthesis. Located on top of the catalytic F1 sector, it makes stable contacts with both F1 and the peripheral stalk, ensuring the structural and functional coupling between F(O) and F1, which is disrupted by the antibiotic, oligomycin. Recent data have established that OSCP is the binding target of cyclophilin (CyP) D, a well-characterized inducer of the mitochondrial permeability transition pore (PTP), whose opening can precipitate cell death. CyPD binding affects ATP synthase activity, and most importantly, it decreases the threshold matrix Ca²⁺ required for PTP opening, in striking analogy with benzodiazepine 423, an apoptosis-inducing agent that also binds OSCP. These findings are consistent with the demonstration that dimers of ATP synthase generate Ca²⁺-dependent currents with features indistinguishable from those of the PTP and suggest that ATP synthase is directly involved in PTP formation, although the underlying mechanism remains to be established. In this scenario, OSCP appears to play a fundamental role, sensing the signal(s) that switches the enzyme of life in a channel able to precipitate cell death.
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Affiliation(s)
- Manuela Antoniel
- Department of Biomedical Sciences, University of Padova, via Ugo Bassi 58/B, 35121 Padua, Italy.
| | - Valentina Giorgio
- Department of Biomedical Sciences, University of Padova, via Ugo Bassi 58/B, 35121 Padua, Italy.
| | - Federico Fogolari
- Department of Biomedical Sciences, University of Udine, p.le Kolbe, 33100 Udine, Italy.
| | - Gary D Glick
- Department of Chemistry, Graduate Program in Immunology, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Paolo Bernardi
- Department of Biomedical Sciences, University of Padova, via Ugo Bassi 58/B, 35121 Padua, Italy.
| | - Giovanna Lippe
- Department of Food Science, University of Udine, via Sondrio 2/A, 33100 Udine, Italy.
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20
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Abstract
Subunit rotation is the mechanochemical intermediate for the catalytic activity of the membrane enzyme FoF1-ATP synthase. smFRET (single-molecule FRET) studies have provided insights into the step sizes of the F1 and Fo motors, internal transient elastic energy storage and controls of the motors. To develop and interpret smFRET experiments, atomic structural information is required. The recent F1 structure of the Escherichia coli enzyme with the ϵ-subunit in an inhibitory conformation initiated a study for real-time monitoring of the conformational changes of ϵ. The present mini-review summarizes smFRET rotation experiments and previews new smFRET data on the conformational changes of the CTD (C-terminal domain) of ϵ in the E. coli enzyme.
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21
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Duncan TM, Düser MG, Heitkamp T, McMillan DGG, Börsch M. Regulatory conformational changes of the ε subunit in single FRET-labeled F oF 1-ATP synthase. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2014; 8948:89481J. [PMID: 25076824 DOI: 10.1117/12.2040463] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Subunit ε is an intrinsic regulator of the bacterial FoF1-ATP synthase, the ubiquitous membrane-embedded enzyme that utilizes a proton motive force in most organisms to synthesize adenosine triphosphate (ATP). The C-terminal domain of ε can extend into the central cavity formed by the α and β subunits, as revealed by the recent X-ray structure of the F1 portion of the Escherichia coli enzyme. This insertion blocks the rotation of the central γ subunit and, thereby, prevents wasteful ATP hydrolysis. Here we aim to develop an experimental system that can reveal conditions under which ε inhibits the holoenzyme FoF1-ATP synthase in vitro. Labeling the C-terminal domain of ε and the γ subunit specifically with two different fluorophores for single-molecule Förster resonance energy transfer (smFRET) allowed monitoring of the conformation of ε in the reconstituted enzyme in real time. New mutants were made for future three-color smFRET experiments to unravel the details of regulatory conformational changes in ε.
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Affiliation(s)
- Thomas M Duncan
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Monika G Düser
- 3 Institute of Physics, Stuttgart University, Stuttgart, Germany
| | - Thomas Heitkamp
- Single-Molecule Microscopy Group, Jena University Hospital, Friedrich Schiller University, Jena, Germany
| | - Duncan G G McMillan
- Single-Molecule Microscopy Group, Jena University Hospital, Friedrich Schiller University, Jena, Germany
| | - Michael Börsch
- Single-Molecule Microscopy Group, Jena University Hospital, Friedrich Schiller University, Jena, Germany
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22
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Stewart AG, Laming EM, Sobti M, Stock D. Rotary ATPases--dynamic molecular machines. Curr Opin Struct Biol 2013; 25:40-8. [PMID: 24878343 DOI: 10.1016/j.sbi.2013.11.013] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 11/20/2013] [Accepted: 11/26/2013] [Indexed: 01/14/2023]
Abstract
Recent work has provided the detailed overall architecture and subunit composition of three subtypes of rotary ATPases. Composite models of F-type, V-type and A-type ATPases have been constructed by fitting high-resolution X-ray structures of individual components into electron microscopy derived envelopes of the intact enzymes. Electron cryo-tomography has provided new insights into the supra-molecular arrangement of eukaryotic ATP synthases within mitochondria. An inherent flexibility in rotary ATPases observed by different techniques suggests greater dynamics during operation than previously envisioned. The concerted movement of subunits within the complex might provide means of regulation and information transfer between distant parts of rotary ATPases thereby fine tuning these molecular machines to their cellular environment, while optimizing their efficiency.
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Affiliation(s)
- Alastair G Stewart
- The Victor Chang Cardiac Research Institute, Sydney, NSW, Australia; The University of New South Wales, Sydney, NSW, Australia.
| | - Elise M Laming
- The Victor Chang Cardiac Research Institute, Sydney, NSW, Australia; The University of New South Wales, Sydney, NSW, Australia
| | - Meghna Sobti
- The Victor Chang Cardiac Research Institute, Sydney, NSW, Australia; The University of New South Wales, Sydney, NSW, Australia
| | - Daniela Stock
- The Victor Chang Cardiac Research Institute, Sydney, NSW, Australia; The University of New South Wales, Sydney, NSW, Australia
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23
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Phosphate release coupled to rotary motion of F1-ATPase. Proc Natl Acad Sci U S A 2013; 110:16468-73. [PMID: 24062450 DOI: 10.1073/pnas.1305497110] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
F1-ATPase, the catalytic domain of ATP synthase, synthesizes most of the ATP in living organisms. Running in reverse powered by ATP hydrolysis, this hexameric ring-shaped molecular motor formed by three αβ-dimers creates torque on its central γ-subunit. This reverse operation enables detailed explorations of the mechanochemical coupling mechanisms in experiment and simulation. Here, we use molecular dynamics simulations to construct a first atomistic conformation of the intermediate state following the 40° substep of rotary motion, and to study the timing and molecular mechanism of inorganic phosphate (Pi) release coupled to the rotation. In response to torque-driven rotation of the γ-subunit in the hydrolysis direction, the nucleotide-free αβE interface forming the "empty" E site loosens and singly charged Pi readily escapes to the P loop. By contrast, the interface stays closed with doubly charged Pi. The γ-rotation tightens the ATP-bound αβTP interface, as required for hydrolysis. The calculated rate for the outward release of doubly charged Pi from the αβE interface 120° after ATP hydrolysis closely matches the ~1-ms functional timescale. Conversely, Pi release from the ADP-bound αβDP interface postulated in earlier models would occur through a kinetically infeasible inward-directed pathway. Our simulations help reconcile conflicting interpretations of single-molecule experiments and crystallographic studies by clarifying the timing of Pi exit, its pathway and kinetics, associated changes in Pi protonation, and changes of the F1-ATPase structure in the 40° substep. Important elements of the molecular mechanism of Pi release emerging from our simulations appear to be conserved in myosin despite the different functional motions.
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24
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Abstract
Molecular bioenergetics deals with the construction, function and regulation of the powerhouses of life. The present overview sketches scenes and actors, farsighted goals and daring hypotheses, meticulous tool-making, painstaking benchwork, lucky discovery, serious scepticism, emphatic believing and strong characters with weak and others with hard arguments, told from a personal, admittedly limited, perspective. Bioenergetics will blossom further with the search focused on both where there is bright light for ever-finer detail and the obvious dark spots for surprise and discovery.
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25
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Börsch M. Microscopy of single F(o) F(1) -ATP synthases--the unraveling of motors, gears, and controls. IUBMB Life 2013; 65:227-37. [PMID: 23378185 DOI: 10.1002/iub.1149] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 01/12/2013] [Indexed: 11/09/2022]
Abstract
Optical microscopy of single F(1) -ATPase and F(o) F(1) -ATP synthases started 15 years ago. Direct demonstration of ATP-driven subunit rotation by videomicroscopy became the new exciting tool to analyze the conformational changes of this enzyme during catalysis. Stimulated by these experiments, technical improvements for higher time resolution, better angular resolution, and reduced viscous drag were developed rapidly. Optics and single-molecule enzymology were entangled to benefit both biochemists and microscopists. Today, several single-molecule microscopy methods are established including controls for the precise nanomanipulation of individual enzymes in vitro. Förster resonance energy transfer, which has been used for simultaneous monitoring of conformational changes of different parts of this rotary motor, is one of them and may become the tool for the analysis of single F(o) F(1) -ATP synthases in membranes of living cells. Here, breakthrough experiments are critically reviewed and challenges are discussed for the future microscopy of single ATP synthesizing enzymes at work.
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Affiliation(s)
- Michael Börsch
- Single-Molecule Microscopy Group, Jena University Hospital, Friedrich Schiller University, Jena, Germany.
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26
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Abstract
The esteemed physicist Erwin Schrödinger, whose name is associated with the most notorious equation of quantum mechanics, also wrote a brief essay entitled 'What is Life?', asking: 'How can the events in space and time which take place within the spatial boundary of a living organism be accounted for by physics and chemistry?' The 60+ years following this seminal work have seen enormous developments in our understanding of biology on the molecular scale, with physics playing a key role in solving many central problems through the development and application of new physical science techniques, biophysical analysis and rigorous intellectual insight. The early days of single-molecule biophysics research was centred around molecular motors and biopolymers, largely divorced from a real physiological context. The new generation of single-molecule bioscience investigations has much greater scope, involving robust methods for understanding molecular-level details of the most fundamental biological processes in far more realistic, and technically challenging, physiological contexts, emerging into a new field of 'single-molecule cellular biophysics'. Here, I outline how this new field has evolved, discuss the key active areas of current research and speculate on where this may all lead in the near future.
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Affiliation(s)
- Mark C Leake
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK.
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