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Nakano A, Kishikawa JI, Mitsuoka K, Yokoyama K. Mechanism of ATP hydrolysis dependent rotation of bacterial ATP synthase. Nat Commun 2023; 14:4090. [PMID: 37429854 DOI: 10.1038/s41467-023-39742-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 06/26/2023] [Indexed: 07/12/2023] Open
Abstract
F1 domain of ATP synthase is a rotary ATPase complex in which rotation of central γ-subunit proceeds in 120° steps against a surrounding α3β3 fueled by ATP hydrolysis. How the ATP hydrolysis reactions occurring in three catalytic αβ dimers are coupled to mechanical rotation is a key outstanding question. Here we describe catalytic intermediates of the F1 domain in FoF1 synthase from Bacillus PS3 sp. during ATP mediated rotation captured using cryo-EM. The structures reveal that three catalytic events and the first 80° rotation occur simultaneously in F1 domain when nucleotides are bound at all the three catalytic αβ dimers. The remaining 40° rotation of the complete 120° step is driven by completion of ATP hydrolysis at αDβD, and proceeds through three sub-steps (83°, 91°, 101°, and 120°) with three associated conformational intermediates. All sub-steps except for one between 91° and 101° associated with phosphate release, occur independently of the chemical cycle, suggesting that the 40° rotation is largely driven by release of intramolecular strain accumulated by the 80° rotation. Together with our previous results, these findings provide the molecular basis of ATP driven rotation of ATP synthases.
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Affiliation(s)
- Atsuki Nakano
- Department of Molecular Biosciences, Kyoto Sangyo University, Kamigamo-Motoyama, Kita-ku, Kyoto, 603-8555, Japan
| | - Jun-Ichi Kishikawa
- Department of Molecular Biosciences, Kyoto Sangyo University, Kamigamo-Motoyama, Kita-ku, Kyoto, 603-8555, Japan
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Kaoru Mitsuoka
- Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, Osaka, Japan
| | - Ken Yokoyama
- Department of Molecular Biosciences, Kyoto Sangyo University, Kamigamo-Motoyama, Kita-ku, Kyoto, 603-8555, Japan.
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Yokoyama K. Rotary mechanism of V/A-ATPases-how is ATP hydrolysis converted into a mechanical step rotation in rotary ATPases? Front Mol Biosci 2023; 10:1176114. [PMID: 37168257 PMCID: PMC10166205 DOI: 10.3389/fmolb.2023.1176114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 04/13/2023] [Indexed: 05/13/2023] Open
Abstract
V/A-ATPase is a rotary molecular motor protein that produces ATP through the rotation of its central rotor. The soluble part of this protein, the V1 domain, rotates upon ATP hydrolysis. However, the mechanism by which ATP hydrolysis in the V1 domain couples with the mechanical rotation of the rotor is still unclear. Cryo-EM snapshot analysis of V/A-ATPase indicated that three independent and simultaneous catalytic events occurred at the three catalytic dimers (ABopen, ABsemi, and ABclosed), leading to a 120° rotation of the central rotor. Besides the closing motion caused by ATP bound to ABopen, the hydrolysis of ATP bound to ABsemi drives the 120° step. Our recent time-resolved cryo-EM snapshot analysis provides further evidence for this model. This review aimed to provide a comprehensive overview of the structure and function of V/A-ATPase from a thermophilic bacterium, one of the most well-studied rotary ATPases to date.
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Abstract
F1-ATPase is a rotary molecular motor that in vivo is subject to strong nonequilibrium driving forces. There is great interest in understanding the operational principles governing its high efficiency of free-energy transduction. Here we use a near-equilibrium framework to design a nontrivial control protocol to minimize dissipation in rotating F1 to synthesize adenosine triphosphate. We find that the designed protocol requires much less work than a naive (constant-velocity) protocol across a wide range of protocol durations. Our analysis points to a possible mechanism for energetically efficient driving of F1 in vivo and provides insight into free-energy transduction for a broader class of biomolecular and synthetic machines.
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Affiliation(s)
- Deepak Gupta
- Department of Physics, Simon Fraser University, BurnabyV5A 1S6, British Columbia, Canada
- Institute for Theoretical Physics, Technical University of Berlin, Hardenbergstr. 36, BerlinD-10623, Germany
| | - Steven J Large
- Department of Physics, Simon Fraser University, BurnabyV5A 1S6, British Columbia, Canada
| | - Shoichi Toyabe
- Department of Applied Physics, Tohoku University, Aoba 6-6-05, Sendai980-8579, Japan
| | - David A Sivak
- Department of Physics, Simon Fraser University, BurnabyV5A 1S6, British Columbia, Canada
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Frasch WD, Bukhari ZA, Yanagisawa S. F1FO ATP synthase molecular motor mechanisms. Front Microbiol 2022; 13:965620. [PMID: 36081786 PMCID: PMC9447477 DOI: 10.3389/fmicb.2022.965620] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 07/26/2022] [Indexed: 11/13/2022] Open
Abstract
The F-ATP synthase, consisting of F1 and FO motors connected by a central rotor and the stators, is the enzyme responsible for synthesizing the majority of ATP in all organisms. The F1 (αβ)3 ring stator contains three catalytic sites. Single-molecule F1 rotation studies revealed that ATP hydrolysis at each catalytic site (0°) precedes a power-stroke that rotates subunit-γ 120° with angular velocities that vary with rotational position. Catalytic site conformations vary relative to subunit-γ position (βE, empty; βD, ADP bound; βT, ATP-bound). During a power stroke, βE binds ATP (0°–60°) and βD releases ADP (60°–120°). Årrhenius analysis of the power stroke revealed that elastic energy powers rotation via unwinding the γ-subunit coiled-coil. Energy from ATP binding at 34° closes βE upon subunit-γ to drive rotation to 120° and forcing the subunit-γ to exchange its tether from βE to βD, which changes catalytic site conformations. In F1FO, the membrane-bound FO complex contains a ring of c-subunits that is attached to subunit-γ. This c-ring rotates relative to the subunit-a stator in response to transmembrane proton flow driven by a pH gradient, which drives subunit-γ rotation in the opposite direction to force ATP synthesis in F1. Single-molecule studies of F1FO embedded in lipid bilayer nanodisks showed that the c-ring transiently stopped F1-ATPase-driven rotation every 36° (at each c-subunit in the c10-ring of E. coli F1FO) and was able to rotate 11° in the direction of ATP synthesis. Protonation and deprotonation of the conserved carboxyl group on each c-subunit is facilitated by separate groups of subunit-a residues, which were determined to have different pKa’s. Mutations of any of any residue from either group changed both pKa values, which changed the occurrence of the 11° rotation proportionately. This supports a Grotthuss mechanism for proton translocation and indicates that proton translocation occurs during the 11° steps. This is consistent with a mechanism in which each 36° of rotation the c-ring during ATP synthesis involves a proton translocation-dependent 11° rotation of the c-ring, followed by a 25° rotation driven by electrostatic interaction of the negatively charged unprotonated carboxyl group to the positively charged essential arginine in subunit-a.
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Nakayama Y, Toyabe S. Optimal Rectification without Forward-Current Suppression by Biological Molecular Motor. PHYSICAL REVIEW LETTERS 2021; 126:208101. [PMID: 34110213 DOI: 10.1103/physrevlett.126.208101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 04/23/2021] [Indexed: 06/12/2023]
Abstract
We experimentally show that biological molecular motor F_{1}-ATPase (F_{1}) implements an optimal rectification mechanism. The rectification mechanism hardly suppresses the synthesis of adenosine triphosphate by F_{1}, which is F_{1}'s physiological role, while inhibiting the unfavorable hydrolysis of adenosine triphosphate. This optimal rectification contrasts highly with that of a simple ratchet model, where the inhibition of the backward current is inevitably accompanied by the suppression of the forward current. Our detailed analysis of single-molecule trajectories demonstrates a novel but simple rectification mechanism of F_{1} with parallel landscapes and asymmetric transition rates.
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Affiliation(s)
- Yohei Nakayama
- Department of Applied Physics, Graduate School of Engineering, Tohoku University, Aoba 6-6-05, Sendai 980-8579, Japan
| | - Shoichi Toyabe
- Department of Applied Physics, Graduate School of Engineering, Tohoku University, Aoba 6-6-05, Sendai 980-8579, Japan
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Kasper AKS, Sivak DA. Modeling work-speed-accuracy trade-offs in a stochastic rotary machine. Phys Rev E 2021; 101:032110. [PMID: 32289954 DOI: 10.1103/physreve.101.032110] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Accepted: 01/30/2020] [Indexed: 11/07/2022]
Abstract
Molecular machines are stochastic systems that catalyze the energetic processes keeping living cells alive and structured. Inspired by the examples of F_{1}-ATP synthase and the bacterial flagellum, we present a minimal model of an externally driven stochastic rotary machine. We explore the trade-offs of work, driving speed, and driving accuracy when changing driving strength, speed, and the underlying system dynamics. We find an upper bound on accuracy and work for a particular speed. Our results favor slow driving when tasked with minimizing the work-accuracy ratio and maximizing the rate of successful cycles. Finally, in the parameter regime mapping to the dynamics of F_{1}-ATP synthase, we find a significant decay of driving accuracy at physiological rotation rates, raising questions about how ATP synthase achieves reasonable or even remarkable efficiency in vivo.
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Affiliation(s)
- Alexandra K S Kasper
- Department of Physics, Simon Fraser University, Burnaby, British Columbia, Canada V5A1S6
| | - David A Sivak
- Department of Physics, Simon Fraser University, Burnaby, British Columbia, Canada V5A1S6
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Zahoor A, Messerschmidt K, Boecker S, Klamt S. ATPase-based implementation of enforced ATP wasting in Saccharomyces cerevisiae for improved ethanol production. BIOTECHNOLOGY FOR BIOFUELS 2020; 13:185. [PMID: 33292464 PMCID: PMC7654063 DOI: 10.1186/s13068-020-01822-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 10/23/2020] [Indexed: 05/06/2023]
Abstract
BACKGROUND Enforced ATP wasting has been recognized as a promising metabolic engineering strategy to enhance the microbial production of metabolites that are coupled to ATP generation. It also appears to be a suitable approach to improve production of ethanol by Saccharomyces cerevisiae. In the present study, we constructed different S. cerevisiae strains with heterologous expression of genes of the ATP-hydrolyzing F1-part of the ATPase enzyme to induce enforced ATP wasting and quantify the resulting effect on biomass and ethanol formation. RESULTS In contrast to genomic integration, we found that episomal expression of the αβγ subunits of the F1-ATPase genes of Escherichia coli in S. cerevisiae resulted in significantly increased ATPase activity, while neither genomic integration nor episomal expression of the β subunit from Trichoderma reesei could enhance ATPase activity. When grown in minimal medium under anaerobic growth-coupled conditions, the strains expressing E. coli's F1-ATPase genes showed significantly improved ethanol yield (increase of 10% compared to the control strain). However, elevated product formation reduces biomass formation and, therefore, volumetric productivity. We demonstrate that this negative effect can be overcome under growth-decoupled (nitrogen-starved) operation with high and constant biomass concentration. Under these conditions, which mimic the second (production) phase of a two-stage fermentation process, the ATPase-expressing strains showed significant improvement in volumetric productivity (up to 111%) compared to the control strain. CONCLUSIONS Our study shows that expression of genes of the F1-portion of E. coli's ATPase induces ATPase activity in S. cerevisiae and can be a promising way to improve ethanol production. This ATP-wasting strategy can be easily applied to other metabolites of interest, whose formation is coupled to ATP generation.
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Affiliation(s)
- Ahmed Zahoor
- Analysis and Redesign of Biological Networks, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
| | - Katrin Messerschmidt
- Analysis and Redesign of Biological Networks, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
| | - Simon Boecker
- Analysis and Redesign of Biological Networks, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
| | - Steffen Klamt
- Analysis and Redesign of Biological Networks, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany.
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Esparza-Moltó PB, Cuezva JM. Reprogramming Oxidative Phosphorylation in Cancer: A Role for RNA-Binding Proteins. Antioxid Redox Signal 2020; 33:927-945. [PMID: 31910046 DOI: 10.1089/ars.2019.7988] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Significance: Cancer is a major disease imposing high personal and economic burden draining large part of National Health Care and Research budgets worldwide. In the last decade, research in cancer has underscored the reprogramming of metabolism to an enhanced aerobic glycolysis as a major trait of the cancer phenotype with great potential for targeted therapy. Recent Advances: Mitochondria are essential organelles in metabolic reprogramming for controlling the production of biological energy through oxidative phosphorylation (OXPHOS) and the supply of metabolic precursors that sustain proliferation. In addition, mitochondria are critical hubs that integrate different signaling pathways that control cellular metabolism and cell fate. The mitochondrial ATP synthase plays a fundamental role in OXPHOS and cellular signaling. Critical Issues: This review overviews mitochondrial metabolism and OXPHOS, and the major changes reported in the expression and function of mitochondrial proteins of OXPHOS in oncogenesis and in cellular differentiation. We summarize the prominent role that RNA-binding proteins (RNABPs) play in the sorting and localized translation of nuclear-encoded mRNAs that help define the mitochondrial cell-type-specific phenotype. Moreover, we emphasize the mechanisms that contribute to restrain the activity and expression of the mitochondrial ATP synthase in carcinomas, and illustrate that the dysregulation of proteins that control energy metabolism correlates with patients' survival. Future Directions: Future research should elucidate the mechanisms and RNABPs that promote the specific alterations of the mitochondrial phenotype in carcinomas arising from different tissues with the final aim of developing new therapeutic strategies to treat cancer.
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Affiliation(s)
- Pau B Esparza-Moltó
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid (CSIC-UAM), Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII, Instituto de Investigación Hospital 12 de Octubre, Universidad Autónoma de Madrid, Madrid, Spain
| | - José M Cuezva
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid (CSIC-UAM), Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII, Instituto de Investigación Hospital 12 de Octubre, Universidad Autónoma de Madrid, Madrid, Spain
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9
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Tanaka M, Kawakami T, Okaniwa T, Nakayama Y, Toyabe S, Ueno H, Muneyuki E. Tight Chemomechanical Coupling of the F 1 Motor Relies on Structural Stability. Biophys J 2020; 119:48-54. [PMID: 32531205 DOI: 10.1016/j.bpj.2020.04.039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 03/31/2020] [Accepted: 04/06/2020] [Indexed: 11/19/2022] Open
Abstract
The F1 motor is a rotating molecular motor that ensures a tight chemomechanical coupling between ATP hydrolysis/synthesis reactions and rotation steps. However, the mechanism underlying this tight coupling remains to be elucidated. In this study, we used electrorotation in single-molecule experiments using an F1βE190D mutant to demonstrate that the stall torque was significantly smaller than the wild-type F1, indicating a loose coupling of this mutant, despite showing similar stepping torque as the wild-type. Experiments on the ATPase activity after heat treatment and gel filtration of the α3β3-subcomplex revealed the unstable structure of the βE190D mutant. Our results suggest that the tight chemomechanical coupling of the F1 motor relies on the structural stability of F1. We also discuss the difference between the stepping torque and the stall torque.
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Affiliation(s)
- Mana Tanaka
- Department of Physics, Faculty of Science and Engineering, Chuo University, Tokyo, Japan
| | - Tomohiro Kawakami
- Department of Physics, Faculty of Science and Engineering, Chuo University, Tokyo, Japan
| | - Tomoaki Okaniwa
- Department of Physics, Faculty of Science and Engineering, Chuo University, Tokyo, Japan
| | - Yohei Nakayama
- Department of Applied Physics, Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Shoichi Toyabe
- Department of Applied Physics, Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Hiroshi Ueno
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, Tokyo, Japan.
| | - Eiro Muneyuki
- Department of Physics, Faculty of Science and Engineering, Chuo University, Tokyo, Japan.
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Method to extract multiple states in F 1-ATPase rotation experiments from jump distributions. Proc Natl Acad Sci U S A 2019; 116:25456-25461. [PMID: 31776250 DOI: 10.1073/pnas.1915314116] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A method is proposed for analyzing fast (10 μs) single-molecule rotation trajectories in F1 adenosinetriphosphatase ([Formula: see text]-ATPase). This method is based on the distribution of jumps in the rotation angle that occur in the transitions during the steps between subsequent catalytic dwells. The method is complementary to the "stalling" technique devised by H. Noji et al. [Biophys. Rev. 9, 103-118, 2017], and can reveal multiple states not directly detectable as steps. A bimodal distribution of jumps is observed at certain angles, due to the system being in either of 2 states at the same rotation angle. In this method, a multistate theory is used that takes into account a viscoelastic fluctuation of the imaging probe. Using an established sequence of 3 specific states, a theoretical profile of angular jumps is predicted, without adjustable parameters, that agrees with experiment for most of the angular range. Agreement can be achieved at all angles by assuming a fourth state with an ∼10 μs lifetime and a dwell angle about 40° after the adenosine 5'-triphosphate (ATP) binding dwell. The latter result suggests that the ATP binding in one β subunit and the adenosine 5'-diphosphate (ADP) release from another β subunit occur via a transient whose lifetime is ∼10 μs and is about 6 orders of magnitude smaller than the lifetime for ADP release from a singly occupied [Formula: see text]-ATPase. An internal consistency test is given by comparing 2 independent ways of obtaining the relaxation time of the probe. They agree and are ∼15 μs.
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11
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Insights into the origin of the high energy-conversion efficiency of F 1-ATPase. Proc Natl Acad Sci U S A 2019; 116:15924-15929. [PMID: 31341091 DOI: 10.1073/pnas.1906816116] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Our understanding of the rotary-coupling mechanism of F1-ATPase has been greatly enhanced in the last decade by advances in X-ray crystallography, single-molecular imaging, and theoretical models. Recently, Volkán-Kacsó and Marcus [S. Volkán-Kacsó, R. A. Marcus, Proc. Natl. Acad. Sci. U.S.A. 112, 14230 (2015)] presented an insightful thermodynamic model based on the Marcus reaction theory coupled with an elastic structural deformation term to explain the observed γ-rotation angle dependence of the adenosine triphosphate (ATP)/adenosine diphosphate (ADP) exchange rates of F1-ATPase. Although the model is successful in correlating single-molecule data, it is not in agreement with the available theoretical results. We describe a revision of the model, which leads to consistency with the simulation results and other experimental data on the F1-ATPase rotor compliance. Although the free energy liberated on ATP hydrolysis by F1-ATPase is rapidly dissipated as heat and so cannot contribute directly to the rotation, we show how, nevertheless, F1-ATPase functions near the maximum possible efficiency. This surprising result is a consequence of the differential binding of ATP and its hydrolysis products ADP and Pi along a well-defined pathway.
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12
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Essential Role of the ε Subunit for Reversible Chemo-Mechanical Coupling in F 1-ATPase. Biophys J 2019; 114:178-187. [PMID: 29320685 DOI: 10.1016/j.bpj.2017.11.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 10/31/2017] [Accepted: 11/06/2017] [Indexed: 11/22/2022] Open
Abstract
F1-ATPase is a rotary motor protein driven by ATP hydrolysis. Among molecular motors, F1 exhibits unique high reversibility in chemo-mechanical coupling, synthesizing ATP from ADP and inorganic phosphate upon forcible rotor reversal. The ε subunit enhances ATP synthesis coupling efficiency to > 70% upon rotation reversal. However, the detailed mechanism has remained elusive. In this study, we performed stall-and-release experiments to elucidate how the ε subunit modulates ATP association/dissociation and hydrolysis/synthesis process kinetics and thermodynamics, key reaction steps for efficient ATP synthesis. The ε subunit significantly accelerated the rates of ATP dissociation and synthesis by two- to fivefold, whereas those of ATP binding and hydrolysis were not enhanced. Numerical analysis based on the determined kinetic parameters quantitatively reproduced previous findings of two- to fivefold coupling efficiency improvement by the ε subunit at the condition exhibiting the maximum ATP synthesis activity, a physiological role of F1-ATPase. Furthermore, fundamentally similar results were obtained upon ε subunit C-terminal domain truncation, suggesting that the N-terminal domain is responsible for the rate enhancement.
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Lucero JNE, Mehdizadeh A, Sivak DA. Optimal control of rotary motors. Phys Rev E 2019; 99:012119. [PMID: 30780326 DOI: 10.1103/physreve.99.012119] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Indexed: 06/09/2023]
Abstract
Single-molecule experiments have found near-perfect thermodynamic efficiency in the rotary motor F_{1}-ATP synthase. To help elucidate the principles underlying nonequilibrium energetic efficiency in such stochastic machines, we investigate driving protocols that minimize dissipation near equilibrium in a simple model rotary mechanochemical motor, as determined by a generalized friction coefficient. Our simple model has a periodic friction coefficient that peaks near system energy barriers. This implies a minimum-dissipation protocol that proceeds rapidly when the system is overwhelmingly in a single macrostate but slows significantly near energy barriers, thereby harnessing thermal fluctuations to kick the system over energy barriers with minimal work input. This model also manifests a phenomenon not seen in otherwise similar nonperiodic systems: Sufficiently fast protocols can effectively lap the system. While this leads to a trade-off between accuracy of driving and energetic cost, we find that our designed protocols outperform naive protocols.
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Affiliation(s)
- Joseph N E Lucero
- Department of Physics, Simon Fraser University, Burnaby, BC, V5A1S6 Canada
| | | | - David A Sivak
- Department of Physics, Simon Fraser University, Burnaby, BC, V5A1S6 Canada
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15
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Elastic coupling power stroke mechanism of the F 1-ATPase molecular motor. Proc Natl Acad Sci U S A 2018; 115:5750-5755. [PMID: 29760063 PMCID: PMC5984535 DOI: 10.1073/pnas.1803147115] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The angular velocity profile of the 120° F1-ATPase power stroke was resolved as a function of temperature from 16.3 to 44.6 °C using a ΔμATP = -31.25 kBT at a time resolution of 10 μs. Angular velocities during the first 60° of the power stroke (phase 1) varied inversely with temperature, resulting in negative activation energies with a parabolic dependence. This is direct evidence that phase 1 rotation derives from elastic energy (spring constant, κ = 50 kBT·rad-2). Phase 2 of the power stroke had an enthalpic component indicating that additional energy input occurred to enable the γ-subunit to overcome energy stored by the spring after rotating beyond its 34° equilibrium position. The correlation between the probability distribution of ATP binding to the empty catalytic site and the negative Ea values of the power stroke during phase 1 suggests that this additional energy is derived from the binding of ATP to the empty catalytic site. A second torsion spring (κ = 150 kBT·rad-2; equilibrium position, 90°) was also evident that mitigated the enthalpic cost of phase 2 rotation. The maximum ΔGǂ was 22.6 kBT, and maximum efficiency was 72%. An elastic coupling mechanism is proposed that uses the coiled-coil domain of the γ-subunit rotor as a torsion spring during phase 1, and then as a crankshaft driven by ATP-binding-dependent conformational changes during phase 2 to drive the power stroke.
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16
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Esparza-Moltó PB, Cuezva JM. The Role of Mitochondrial H +-ATP Synthase in Cancer. Front Oncol 2018; 8:53. [PMID: 29564224 PMCID: PMC5845864 DOI: 10.3389/fonc.2018.00053] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 02/20/2018] [Indexed: 01/23/2023] Open
Abstract
Cancer cells reprogram energy metabolism by boosting aerobic glycolysis as a main pathway for the provision of metabolic energy and of precursors for anabolic purposes. Accordingly, the relative expression of the catalytic subunit of the mitochondrial H+-ATP synthase—the core hub of oxidative phosphorylation—is downregulated in human carcinomas when compared with its expression in normal tissues. Moreover, some prevalent carcinomas also upregulate the ATPase inhibitory factor 1 (IF1), which is the physiological inhibitor of the H+-ATP synthase. IF1 overexpression, both in cells in culture and in tissue-specific mouse models, is sufficient to reprogram energy metabolism to an enhanced glycolysis by limiting ATP production by the H+-ATP synthase. Furthermore, the IF1-mediated inhibition of the H+-ATP synthase promotes the production of mitochondrial ROS (mtROS). mtROS modulate signaling pathways favoring cellular proliferation and invasion, the activation of antioxidant defenses, resistance to cell death, and modulation of the tissue immune response, favoring the acquisition of several cancer traits. Consistently, IF1 expression is an independent marker of cancer prognosis. By contrast, inhibition of the H+-ATP synthase by α-ketoglutarate and the oncometabolite 2-hydroxyglutarate, reduces mTOR signaling, suppresses cancer cell growth, and contributes to lifespan extension in several model organisms. Hence, the H+-ATP synthase appears as a conserved hub in mitochondria-to-nucleus signaling controlling cell fate. Unraveling the molecular mechanisms responsible for IF1 upregulation in cancer and the signaling cascades that are modulated by the H+-ATP synthase are of utmost interest to decipher the metabolic and redox circuits contributing to cancer origin and progression.
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Affiliation(s)
- Pau B Esparza-Moltó
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Centro de Investigación Biomédica en Red de Enfermedades Raras CIBERER-ISCIII, Instituto de Investigación Hospital 12 de Octubre (i+12), Universidad Autónoma de Madrid, Madrid, Spain
| | - José M Cuezva
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Centro de Investigación Biomédica en Red de Enfermedades Raras CIBERER-ISCIII, Instituto de Investigación Hospital 12 de Octubre (i+12), Universidad Autónoma de Madrid, Madrid, Spain
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17
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Iino R, Iida T, Nakamura A, Saita EI, You H, Sako Y. Single-molecule imaging and manipulation of biomolecular machines and systems. Biochim Biophys Acta Gen Subj 2017; 1862:241-252. [PMID: 28789884 DOI: 10.1016/j.bbagen.2017.08.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/23/2017] [Accepted: 08/03/2017] [Indexed: 02/08/2023]
Abstract
BACKGROUND Biological molecular machines support various activities and behaviors of cells, such as energy production, signal transduction, growth, differentiation, and migration. SCOPE OF REVIEW We provide an overview of single-molecule imaging methods involving both small and large probes used to monitor the dynamic motions of molecular machines in vitro (purified proteins) and in living cells, and single-molecule manipulation methods used to measure the forces, mechanical properties and responses of biomolecules. We also introduce several examples of single-molecule analysis, focusing primarily on motor proteins and signal transduction systems. MAJOR CONCLUSIONS Single-molecule analysis is a powerful approach to unveil the operational mechanisms both of individual molecular machines and of systems consisting of many molecular machines. GENERAL SIGNIFICANCE Quantitative, high-resolution single-molecule analyses of biomolecular systems at the various hierarchies of life will help to answer our fundamental question: "What is life?" This article is part of a Special Issue entitled "Biophysical Exploration of Dynamical Ordering of Biomolecular Systems" edited by Dr. Koichi Kato.
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Affiliation(s)
- Ryota Iino
- Okazaki Institute for Integrative Bioscience, Institute for Molecular Science, National Institutes of Natural Sciences, Japan; Department of Functional Molecular Science, School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Japan.
| | - Tatsuya Iida
- Okazaki Institute for Integrative Bioscience, Institute for Molecular Science, National Institutes of Natural Sciences, Japan; Department of Functional Molecular Science, School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Japan
| | - Akihiko Nakamura
- Okazaki Institute for Integrative Bioscience, Institute for Molecular Science, National Institutes of Natural Sciences, Japan; Department of Functional Molecular Science, School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Japan
| | - Ei-Ichiro Saita
- Information Processing Biology Unit, Okinawa Institute of Science and Technology Graduate University, Japan
| | - Huijuan You
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, China.
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18
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Esparza-Moltó PB, Nuevo-Tapioles C, Cuezva JM. Regulation of the H +-ATP synthase by IF1: a role in mitohormesis. Cell Mol Life Sci 2017; 74:2151-2166. [PMID: 28168445 PMCID: PMC5425498 DOI: 10.1007/s00018-017-2462-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 01/09/2017] [Accepted: 01/10/2017] [Indexed: 01/18/2023]
Abstract
The mitochondrial H+-ATP synthase is a primary hub of cellular homeostasis by providing the energy required to sustain cellular activity and regulating the production of signaling molecules that reprogram nuclear activity needed for adaption to changing cues. Herein, we summarize findings regarding the regulation of the activity of the H+-ATP synthase by its physiological inhibitor, the ATPase inhibitory factor 1 (IF1) and their functional role in cellular homeostasis. First, we outline the structure and the main molecular mechanisms that regulate the activity of the enzyme. Next, we describe the molecular biology of IF1 and summarize the regulation of IF1 expression and activity as an inhibitor of the H+-ATP synthase emphasizing the role of IF1 as a main driver of energy rewiring and cellular signaling in cancer. Findings in transgenic mice in vivo indicate that the overexpression of IF1 is sufficient to reprogram energy metabolism to an enhanced glycolysis and activate reactive oxygen species (ROS)-dependent signaling pathways that promote cell survival. These findings are placed in the context of mitohormesis, a program in which a mild mitochondrial stress triggers adaptive cytoprotective mechanisms that improve lifespan. In this regard, we emphasize the role played by the H+-ATP synthase in modulating signaling pathways that activate the mitohormetic response, namely ATP, ROS and target of rapamycin (TOR). Overall, we aim to highlight the relevant role of the H+-ATP synthase and of IF1 in cellular physiology and the need of additional studies to decipher their contributions to aging and age-related diseases.
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Affiliation(s)
- Pau B Esparza-Moltó
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, (CSIC-UAM), Centro de Investigación Biomédica en Red de Enfermedades Raras CIBERER-ISCIII, Instituto de Investigación Hospital 12 de Octubre, Universidad Autónoma de Madrid, 28049, Madrid, Spain
| | - Cristina Nuevo-Tapioles
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, (CSIC-UAM), Centro de Investigación Biomédica en Red de Enfermedades Raras CIBERER-ISCIII, Instituto de Investigación Hospital 12 de Octubre, Universidad Autónoma de Madrid, 28049, Madrid, Spain
| | - José M Cuezva
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, (CSIC-UAM), Centro de Investigación Biomédica en Red de Enfermedades Raras CIBERER-ISCIII, Instituto de Investigación Hospital 12 de Octubre, Universidad Autónoma de Madrid, 28049, Madrid, Spain.
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19
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Ai G, Liu P, Ge H. Torque-coupled thermodynamic model for F_{o}F_{1}-ATPase. Phys Rev E 2017; 95:052413. [PMID: 28618520 DOI: 10.1103/physreve.95.052413] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Indexed: 01/23/2023]
Abstract
F_{o}F_{1}-ATPase is a motor protein complex that utilizes transmembrane ion flow to drive the synthesis of adenosine triphosphate (ATP) from adenosine diphosphate (ADP) and phosphate (Pi). While many theoretical models have been proposed to account for its rotary activity, most of them focus on the F_{o} or F_{1} portions separately rather than the complex as a whole. Here, we propose a simple but new torque-coupled thermodynamic model of F_{o}F_{1}-ATPase. Solving this model at steady state, we find that the monotonic variation of each portion's efficiency becomes much more robust over a wide range of parameters when the F_{o} and F_{1} portions are coupled together, as compared to cases when they are considered separately. Furthermore, the coupled model predicts the dependence of each portion's kinetic behavior on the parameters of the other. Specifically, the power and efficiency of the F_{1} portion are quite sensitive to the proton gradient across the membrane, while those of the F_{o} portion as well as the related Michaelis constants for proton concentrations respond insensitively to concentration changes in the reactants of ATP synthesis. The physiological proton gradient across the membrane in the F_{o} portion is also shown to be optimal for the Michaelis constants of ADP and phosphate in the F_{1} portion during ATP synthesis. Together, our coupled model is able to predict key dynamic and thermodynamic features of the F_{o}F_{1}-ATPase in vivo semiquantitatively, and suggests that such coupling approach could be further applied to other biophysical systems.
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Affiliation(s)
- Guangkuo Ai
- Beijing International Center for Mathematical Research and School of Mathematical Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Pengfei Liu
- Applied and Computational Mathematics, California Institute of Technology, Pasadena, California 91125, USA
| | - Hao Ge
- Beijing International Center for Mathematical Research and Biodynamic Optical Imaging Center, Peking University, Beijing 100871, People's Republic of China
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20
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Abstract
FoF1-ATP synthase (FoF1) couples H+ flow in Fo domain and ATP synthesis/hydrolysis in F1 domain through rotation of the central rotor shaft, and the H+/ATP ratio is crucial to understand the coupling mechanism and energy yield in cells. Although H+/ATP ratio of the perfectly coupling enzyme can be predicted from the copy number of catalytic β subunits and that of H+ binding c subunits as c/β, the actual H+/ATP ratio can vary depending on coupling efficiency. Here, we report actual H+/ATP ratio of thermophilic Bacillus FoF1, whose c/β is 10/3. Proteoliposomes reconstituted with the FoF1 were energized with ΔpH and Δψ by the acid-base transition and by valinomycin-mediated diffusion potential of K+ under various [ATP]/([ADP]⋅[Pi]) conditions, and the initial rate of ATP synthesis/hydrolysis was measured. Analyses of thermodynamically equilibrated states, where net ATP synthesis/hydrolysis is zero, show linear correlation between the chemical potential of ATP synthesis/hydrolysis and the proton motive force, giving the slope of the linear function, that is, H+/ATP ratio, 3.3 ± 0.1. This value agrees well with the c/β ratio. Thus, chemomechanical coupling between Fo and F1 is perfect.
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21
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Noji H, Ueno H, McMillan DGG. Catalytic robustness and torque generation of the F 1-ATPase. Biophys Rev 2017; 9:103-118. [PMID: 28424741 PMCID: PMC5380711 DOI: 10.1007/s12551-017-0262-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 03/13/2017] [Indexed: 12/28/2022] Open
Abstract
The F1-ATPase is the catalytic portion of the FoF1 ATP synthase and acts as a rotary molecular motor when it hydrolyzes ATP. Two decades have passed since the single-molecule rotation assay of F1-ATPase was established. Although several fundamental issues remain elusive, basic properties of F-type ATPases as motor proteins have been well characterized, and a large part of the reaction scheme has been revealed by the combination of extensive structural, biochemical, biophysical, and theoretical studies. This review is intended to provide a concise summary of the fundamental features of F1-ATPases, by use of the well-described model F1 from the thermophilic Bacillus PS3 (TF1). In the last part of this review, we focus on the robustness of the rotary catalysis of F1-ATPase to provide a perspective on the re-designing of novel molecular machines.
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Affiliation(s)
- Hiroyuki Noji
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, Tokyo, 113-8656 Japan
| | - Hiroshi Ueno
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, Tokyo, 113-8656 Japan
| | - Duncan G. G. McMillan
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, Tokyo, 113-8656 Japan
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22
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García-Bermúdez J, Cuezva JM. The ATPase Inhibitory Factor 1 (IF1): A master regulator of energy metabolism and of cell survival. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1857:1167-1182. [PMID: 26876430 DOI: 10.1016/j.bbabio.2016.02.004] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Revised: 01/28/2016] [Accepted: 02/07/2016] [Indexed: 12/19/2022]
Abstract
In this contribution we summarize most of the findings reported for the molecular and cellular biology of the physiological inhibitor of the mitochondrial H(+)-ATP synthase, the engine of oxidative phosphorylation (OXPHOS) and gate of cell death. We first describe the structure and major mechanisms and molecules that regulate the activity of the ATP synthase placing the ATPase Inhibitory Factor 1 (IF1) as a major determinant in the regulation of the activity of the ATP synthase and hence of OXPHOS. Next, we summarize the post-transcriptional mechanisms that regulate the expression of IF1 and emphasize, in addition to the regulation afforded by the protonation state of histidine residues, that the activity of IF1 as an inhibitor of the ATP synthase is also regulated by phosphorylation of a serine residue. Phosphorylation of S39 in IF1 by the action of a mitochondrial cAMP-dependent protein kinase A hampers its interaction with the ATP synthase, i.e., only dephosphorylated IF1 interacts with the enzyme. Upon IF1 interaction with the ATP synthase both the synthetic and hydrolytic activities of the engine of OXPHOS are inhibited. These findings are further placed into the physiological context to stress the emerging roles played by IF1 in metabolic reprogramming in cancer, in hypoxia and in cellular differentiation. We review also the implication of IF1 in other cellular situations that involve the malfunctioning of mitochondria. Special emphasis is given to the role of IF1 as driver of the generation of a reactive oxygen species signal that, emanating from mitochondria, is able to reprogram the nucleus of the cell to confer by various signaling pathways a cell-death resistant phenotype against oxidative stress. Overall, our intention is to highlight the urgent need of further investigations in the molecular and cellular biology of IF1 and of its target, the ATP synthase, to unveil new therapeutic strategies in human pathology. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi.
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Affiliation(s)
- Javier García-Bermúdez
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid (CSIC-UAM), Centro de Investigación Biomédica en Red de Enfermedades Raras CIBERER-ISCIII, Instituto de Investigación Hospital 12 de Octubre, Universidad Autónoma de Madrid, 28049, Madrid, Spain
| | - José M Cuezva
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid (CSIC-UAM), Centro de Investigación Biomédica en Red de Enfermedades Raras CIBERER-ISCIII, Instituto de Investigación Hospital 12 de Octubre, Universidad Autónoma de Madrid, 28049, Madrid, Spain.
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23
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Hahn-Herrera O, Salcedo G, Barril X, García-Hernández E. Inherent conformational flexibility of F1-ATPase α-subunit. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:1392-1402. [PMID: 27137408 DOI: 10.1016/j.bbabio.2016.04.283] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 04/12/2016] [Accepted: 04/28/2016] [Indexed: 12/30/2022]
Abstract
The core of F1-ATPase consists of three catalytic (β) and three noncatalytic (α) subunits, forming a hexameric ring in alternating positions. A wealth of experimental and theoretical data has provided a detailed picture of the complex role played by catalytic subunits. Although major conformational changes have only been seen in β-subunits, it is clear that α-subunits have to respond to these changes in order to be able to transmit information during the rotary mechanism. However, the conformational behavior of α-subunits has not been explored in detail. Here, we have combined unbiased molecular dynamics (MD) simulations and calorimetrically measured thermodynamic signatures to investigate the conformational flexibility of isolated α-subunits, as a step toward deepening our understanding of its function inside the α3β3 ring. The simulations indicate that the open-to-closed conformational transition of the α-subunit is essentially barrierless, which is ideal to accompany and transmit the movement of the catalytic subunits. Calorimetric measurements of the recombinant α-subunit from Geobacillus kaustophilus indicate that the isolated subunit undergoes no significant conformational changes upon nucleotide binding. Simulations confirm that the nucleotide-free and nucleotide-bound subunits show average conformations similar to that observed in the F1 crystal structure, but they reveal an increased conformational flexibility of the isolated α-subunit upon MgATP binding, which might explain the evolutionary conserved capacity of α-subunits to recognize nucleotides with considerable strength. Furthermore, we elucidate the different dependencies that α- and β-subunits show on Mg(II) for recognizing ATP.
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Affiliation(s)
- Otto Hahn-Herrera
- Instituto de Química Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, México 04630, D.F., Mexico
| | - Guillermo Salcedo
- Instituto de Química Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, México 04630, D.F., Mexico
| | - Xavier Barril
- Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluís Companys 23, 08010 Barcelona, Spain; Departament de Fisicoquímica, Facultat de Farmàcia, Universitat de Barcelona, Barcelona, Spain
| | - Enrique García-Hernández
- Instituto de Química Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, México 04630, D.F., Mexico.
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24
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Turina P, Petersen J, Gräber P. Thermodynamics of proton transport coupled ATP synthesis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:653-64. [PMID: 26940516 DOI: 10.1016/j.bbabio.2016.02.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 01/16/2016] [Accepted: 02/28/2016] [Indexed: 10/22/2022]
Abstract
The thermodynamic H(+)/ATP ratio of the H(+)-ATP synthase from chloroplasts was measured in proteoliposomes after energization of the membrane by an acid base transition (Turina et al. 2003 [13], 418-422). The method is discussed, and all published data obtained with this system are combined and analyzed as a single dataset. This meta-analysis led to the following results. 1) At equilibrium, the transmembrane ΔpH is energetically equivalent to the transmembrane electric potential difference. 2) The standard free energy for ATP synthesis (reference reaction) is ΔG°(ref)=33.8±1.3kJ/mol. 3) The thermodynamic H(+)/ATP ratio, as obtained from the shift of the ATP synthesis equilibrium induced by changing the transmembrane ΔpH (varying either pH(in) or pH(out)) is 4.0±0.1. The structural H(+)/ATP ratio, calculated from the ratio of proton binding sites on the c-subunit-ring in F(0) to the catalytic nucleotide binding sites on the β-subunits in F(1), is c/β=14/3=4.7. We infer that the energy of 0.7 protons per ATP that flow through the enzyme, but do not contribute to shifting the ATP/(ADP·Pi) ratio, is used for additional processes within the enzyme, such as activation, and/or energy dissipation, due e.g. to internal uncoupling. The ratio between the thermodynamic and the structural H(+)/ATP values is 0.85, and we conclude that this value represents the efficiency of the chemiosmotic energy conversion within the chloroplast H(+)-ATP synthase.
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Affiliation(s)
- Paola Turina
- Department of Biology, BiGeA, University of Bologna, Via Irnerio 42, I-40126 Bologna, Italy
| | - Jan Petersen
- Biomedicine Discovery Institute, Monash University, 1 Wellington Rd., Clayton, Vic 3800, Australia
| | - Peter Gräber
- Institut für Physikalische Chemie, University of Freiburg, Albertstr, 23a, D-79104 Freiburg, Germany.
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25
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Chapman B, Loiselle D. Thermodynamics and kinetics of the FoF1-ATPase: application of the probability isotherm. ROYAL SOCIETY OPEN SCIENCE 2016; 3:150379. [PMID: 26998316 PMCID: PMC4785967 DOI: 10.1098/rsos.150379] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 01/08/2016] [Indexed: 06/05/2023]
Abstract
We use the results of recent publications as vehicles with which to discuss the thermodynamics of the proton-driven mitochondrial F o F1-ATP synthase, focusing particularly on the possibility that there may be dissociation between rotatory steps and ATP synthesis/hydrolysis. Such stoichiometric 'slippage' has been invoked in the literature to explain observed non-ideal behaviour. Numerical solution of the Rate Isotherm (the kinetic equivalent of the more fundamental Probability Isotherm) suggests that such 'slippage' is an unlikely explanation; instead, we suggest that the experimental results may be more consistent with damage to the enzyme caused by its isolation from the biomembrane and its experimental fixation, resulting in non-physiological friction within the enzyme's rotary mechanism. We emphasize the unavoidable constraint of the Second Law as instantiated by the obligatory dissipation of Gibbs Free Energy if the synthase is to operate at anything other than thermodynamic equilibrium. We use further numerical solution of the Rate Isotherm to demonstrate that there is no necessary association of low thermodynamic efficiency with high metabolic rates in a bio-world in which the dominating mechanism of metabolic control is multifactorial enzyme activation.
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Affiliation(s)
- Brian Chapman
- Honorary Principal Research Fellow, School of Applied and Biomedical Science, Faculty of Science and Technology, Federation University Australia, Victoria, Australia
| | - Denis Loiselle
- Department of Physiology and the Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
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