1
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Courbon GM, Rubinstein JL. CryoEM Reveals the Complexity and Diversity of ATP Synthases. Front Microbiol 2022; 13:864006. [PMID: 35783400 PMCID: PMC9244403 DOI: 10.3389/fmicb.2022.864006] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 03/30/2022] [Indexed: 11/14/2022] Open
Abstract
During respiration, adenosine triphosphate (ATP) synthases harness the electrochemical proton motive force (PMF) generated by the electron transport chain (ETC) to synthesize ATP. These macromolecular machines operate by a remarkable rotary catalytic mechanism that couples transmembrane proton translocation to rotation of a rotor subcomplex, and rotation to ATP synthesis. Initially, x-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy, and cross-linking were the only ways to gain insights into the three-dimensional (3D) structures of ATP synthases and, in particular, provided ground-breaking insights into the soluble parts of the complex that explained the catalytic mechanism by which rotation is coupled to ATP synthesis. In contrast, early electron microscopy was limited to studying the overall shape of the assembly. However, advances in electron cryomicroscopy (cryoEM) have allowed determination of high-resolution structures, including the membrane regions of ATP synthases. These studies revealed the high-resolution structures of the remaining ATP synthase subunits and showed how these subunits work together in the intact macromolecular machine. CryoEM continues to uncover the diversity of ATP synthase structures across species and has begun to show how ATP synthases can be targeted by therapies to treat human diseases.
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Affiliation(s)
- Gautier M. Courbon
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Medical Biophysics, The University of Toronto, Toronto, ON, Canada
| | - John L. Rubinstein
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Medical Biophysics, The University of Toronto, Toronto, ON, Canada
- Department of Biochemistry, The University of Toronto, Toronto, ON, Canada
- *Correspondence: John L. Rubinstein
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2
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Krah A, Marzinek JK, Bond PJ. Insights into water accessible pathways and the inactivation mechanism of proton translocation by the membrane-embedded domain of V-type ATPases. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:1004-1010. [DOI: 10.1016/j.bbamem.2019.02.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 01/29/2019] [Accepted: 02/27/2019] [Indexed: 01/25/2023]
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3
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Structural model of a2-subunit N-terminus and its binding interface for Arf-GEF CTH2: Implication for regulation of V-ATPase, CTH2 function and rational drug design. CURRENT TOPICS IN MEMBRANES 2019; 83:77-106. [PMID: 31196611 DOI: 10.1016/bs.ctm.2019.01.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We have previously identified the interaction between mammalian V-ATPase a2-subunit isoform and cytohesin-2 (CTH2) and studied molecular details of binding between these proteins. In particular, we found that six peptides derived from the N-terminal cytosolic domain of a2 subunit (a2N1-402) are involved in interaction with CTH2 (Merkulova, Bakulina, Thaker, Grüber, & Marshansky, 2010). However, the actual 3D binding interface was not determined in that study due to the lack of high-resolution structural information about a-subunits of V-ATPase. Here, using a combination of homology modeling and NMR analysis, we generated the structural model of complete a2N1-402 and uncovered the CTH2-binding interface. First, using the crystal-structure of the bacterial M. rubber Icyt-subunit of A-ATPase as a template (Srinivasan, Vyas, Baker, & Quiocho, 2011), we built a homology model of mammalian a2N1-352 fragment. Next, we combined it with the determined NMR structures of peptides a2N368-395 and a2N386-402 of the C-terminal section of a2N1-402. The complete molecular model of a2N1-402 revealed that six CTH2 interacting peptides are clustered in the distal and proximal lobe sub-domains of a2N1-402. Our data indicate that the proximal lobe sub-domain is the major interacting site with the Sec7 domain of first CTH2 protein, while the distal lobe sub-domain of a2N1-402 interacts with the PH-domain of second CTH2. Indeed, using Sec7/Arf-GEF activity assay we experimentally confirmed our model. The interface formed by peptides a2N1-17 and a2N35-49 is involved in specific interaction with Sec7 domain and regulation of GEF activity. These data are critical for understanding of the cross-talk between V-ATPase and CTH2 as well as for the rational drug design to regulate their function.
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4
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Abstract
F1Fo ATP synthases produce most of the ATP in the cell. F-type ATP synthases have been investigated for more than 50 years, but a full understanding of their molecular mechanisms has become possible only with the recent structures of complete, functionally competent complexes determined by electron cryo-microscopy (cryo-EM). High-resolution cryo-EM structures offer a wealth of unexpected new insights. The catalytic F1 head rotates with the central γ-subunit for the first part of each ATP-generating power stroke. Joint rotation is enabled by subunit δ/OSCP acting as a flexible hinge between F1 and the peripheral stalk. Subunit a conducts protons to and from the c-ring rotor through two conserved aqueous channels. The channels are separated by ∼6 Å in the hydrophobic core of Fo, resulting in a strong local field that generates torque to drive rotary catalysis in F1. The structure of the chloroplast F1Fo complex explains how ATPase activity is turned off at night by a redox switch. Structures of mitochondrial ATP synthase dimers indicate how they shape the inner membrane cristae. The new cryo-EM structures complete our picture of the ATP synthases and reveal the unique mechanism by which they transform an electrochemical membrane potential into biologically useful chemical energy.
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Affiliation(s)
- Werner Kühlbrandt
- Department of Structural Biology, Max Planck Institute of Biophysics, 60438 Frankfurt, Germany;
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5
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Cossio P, Allegretti M, Mayer F, Müller V, Vonck J, Hummer G. Bayesian inference of rotor ring stoichiometry from electron microscopy images of archaeal ATP synthase. Microscopy (Oxf) 2018; 67:266-273. [PMID: 30032235 DOI: 10.1093/jmicro/dfy033] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 06/20/2018] [Indexed: 12/24/2022] Open
Abstract
The 'Bayesian inference of electron microscopy' (BioEM) framework makes it possible to determine the stoichiometry of protein complexes using 3D coarse-grained models and a relatively small number of cryo-electron microscopy images as input. We applied the method to determine the most probable rotor ring stoichiometry of the archaeal Na+ ATP synthase from Pyrococcus furiosus, a multisubunit complex able to produce ATP under extreme conditions. Archaeal ATP synthases consist of a catalytic A1 part and a membrane-embedded AO portion. The AO portion is composed of a rotor ring and the a-subunit. The rotor ring of P. furiosus ATP synthase is composed of 16-kDa c-subunits, each consisting of four helices forming a bundle, with only one Na+-binding site per bundle. This ring was proposed to be decameric from LILBID-MS analysis of the entire ATP synthase. By contrast, the BioEM posterior favors a c9 ring stoichiometry. With BioEM, we ranked coarse-grained models of the whole complex with different ring geometry, using 6400 unprocessed particle images of the A1AO complex collected in vitreous ice. BioEM makes it possible to probabilistically establish the domain stoichiometry using low-resolution information and comparably few particle images.
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Affiliation(s)
- Pilar Cossio
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.,Biophysics of Tropical Diseases, Max Planck Tandem Group, University of Antioquia, Medellín, Colombia
| | - Matteo Allegretti
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Florian Mayer
- Department of Molecular Microbiology & Bioenergetics, Goethe University Frankfurt, Max-von-Laue-Strasse 9, Frankfurt am Main, Germany
| | - Volker Müller
- Department of Molecular Microbiology & Bioenergetics, Goethe University Frankfurt, Max-von-Laue-Strasse 9, Frankfurt am Main, Germany
| | - Janet Vonck
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.,Department of Physics, Goethe University Frankfurt, Max-von-Laue-Strasse 9, Frankfurt am Main, Germany
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6
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Hohlweg W, Wagner GE, Hofbauer HF, Sarkleti F, Setz M, Gubensäk N, Lichtenegger S, Falsone SF, Wolinski H, Kosol S, Oostenbrink C, Kohlwein SD, Zangger K. A cation-π interaction in a transmembrane helix of vacuolar ATPase retains the proton-transporting arginine in a hydrophobic environment. J Biol Chem 2018; 293:18977-18988. [PMID: 30209131 DOI: 10.1074/jbc.ra118.005276] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Revised: 08/24/2018] [Indexed: 11/06/2022] Open
Abstract
Vacuolar ATPases are multisubunit protein complexes that are indispensable for acidification and pH homeostasis in a variety of physiological processes in all eukaryotic cells. An arginine residue (Arg735) in transmembrane helix 7 (TM7) of subunit a of the yeast ATPase is known to be essential for proton translocation. However, the specific mechanism of its involvement in proton transport remains to be determined. Arginine residues are usually assumed to "snorkel" toward the protein surface when exposed to a hydrophobic environment. Here, using solution NMR spectroscopy, molecular dynamics simulations, and in vivo yeast assays, we obtained evidence for the formation of a transient, membrane-embedded cation-π interaction in TM7 between Arg735 and two highly conserved nearby aromatic residues, Tyr733 and Trp737 We propose a mechanism by which the transient, membrane-embedded cation-π complex provides the necessary energy to keep the charged side chain of Arg735 within the hydrophobic membrane. Such cation-π interactions may define a general mechanism to retain charged amino acids in a hydrophobic membrane environment.
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Affiliation(s)
| | - Gabriel E Wagner
- the Institute of Hygiene, Microbiology, and Environmental Medicine, Medical University of Graz, 8010 Graz, Austria
| | - Harald F Hofbauer
- the Institute of Molecular Biosciences, BioTechMed-Graz, University of Graz, 8010 Graz, Austria
| | - Florian Sarkleti
- the Institute of Molecular Biosciences, BioTechMed-Graz, University of Graz, 8010 Graz, Austria
| | - Martina Setz
- the Institute of Molecular Modeling and Simulation, University of Natural Resources and Life Sciences, 1190 Vienna, Austria
| | | | - Sabine Lichtenegger
- the Institute of Hygiene, Microbiology, and Environmental Medicine, Medical University of Graz, 8010 Graz, Austria
| | | | - Heimo Wolinski
- the Institute of Molecular Biosciences, BioTechMed-Graz, University of Graz, 8010 Graz, Austria
| | - Simone Kosol
- the Department of Chemistry, University of Warwick, Gibbet Hill, Coventry CV4 7AL, United Kingdom
| | - Chris Oostenbrink
- the Institute of Molecular Modeling and Simulation, University of Natural Resources and Life Sciences, 1190 Vienna, Austria
| | - Sepp D Kohlwein
- the Institute of Molecular Biosciences, BioTechMed-Graz, University of Graz, 8010 Graz, Austria
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7
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Mendoza-Hoffmann F, Zarco-Zavala M, Ortega R, García-Trejo JJ. Control of rotation of the F1FO-ATP synthase nanomotor by an inhibitory α-helix from unfolded ε or intrinsically disordered ζ and IF1 proteins. J Bioenerg Biomembr 2018; 50:403-424. [DOI: 10.1007/s10863-018-9773-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 09/13/2018] [Indexed: 12/14/2022]
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8
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Colina-Tenorio L, Dautant A, Miranda-Astudillo H, Giraud MF, González-Halphen D. The Peripheral Stalk of Rotary ATPases. Front Physiol 2018; 9:1243. [PMID: 30233414 PMCID: PMC6131620 DOI: 10.3389/fphys.2018.01243] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 08/16/2018] [Indexed: 12/18/2022] Open
Abstract
Rotary ATPases are a family of enzymes that are thought of as molecular nanomotors and are classified in three types: F, A, and V-type ATPases. Two members (F and A-type) can synthesize and hydrolyze ATP, depending on the energetic needs of the cell, while the V-type enzyme exhibits only a hydrolytic activity. The overall architecture of all these enzymes is conserved and three main sectors are distinguished: a catalytic core, a rotor and a stator or peripheral stalk. The peripheral stalks of the A and V-types are highly conserved in both structure and function, however, the F-type peripheral stalks have divergent structures. Furthermore, the peripheral stalk has other roles beyond its stator function, as evidenced by several biochemical and recent structural studies. This review describes the information regarding the organization of the peripheral stalk components of F, A, and V-ATPases, highlighting the key differences between the studied enzymes, as well as the different processes in which the structure is involved.
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Affiliation(s)
- Lilia Colina-Tenorio
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Alain Dautant
- CNRS, UMR5095, IBGC, Bordeaux, France.,Energy Transducing Systems and Mitochondrial Morphology, Université de Bordeaux, Bordeaux, France
| | - Héctor Miranda-Astudillo
- Genetics and Physiology of Microalgae, InBios, PhytoSYSTEMS, University of Liège, Liège, Belgium
| | - Marie-France Giraud
- CNRS, UMR5095, IBGC, Bordeaux, France.,Energy Transducing Systems and Mitochondrial Morphology, Université de Bordeaux, Bordeaux, France
| | - Diego González-Halphen
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
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9
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Hahn A, Vonck J, Mills DJ, Meier T, Kühlbrandt W. Structure, mechanism, and regulation of the chloroplast ATP synthase. Science 2018; 360:eaat4318. [PMID: 29748256 PMCID: PMC7116070 DOI: 10.1126/science.aat4318] [Citation(s) in RCA: 229] [Impact Index Per Article: 38.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 04/09/2018] [Indexed: 12/13/2022]
Abstract
The chloroplast adenosine triphosphate (ATP) synthase uses the electrochemical proton gradient generated by photosynthesis to produce ATP, the energy currency of all cells. Protons conducted through the membrane-embedded Fo motor drive ATP synthesis in the F1 head by rotary catalysis. We determined the high-resolution structure of the complete cF1Fo complex by cryo-electron microscopy, resolving side chains of all 26 protein subunits, the five nucleotides in the F1 head, and the proton pathway to and from the rotor ring. The flexible peripheral stalk redistributes differences in torsional energy across three unequal steps in the rotation cycle. Plant ATP synthase is autoinhibited by a β-hairpin redox switch in subunit γ that blocks rotation in the dark.
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Affiliation(s)
- Alexander Hahn
- Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, 60438 Frankfurt am Main, Germany
| | - Janet Vonck
- Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, 60438 Frankfurt am Main, Germany
| | - Deryck J Mills
- Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, 60438 Frankfurt am Main, Germany
| | - Thomas Meier
- Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, 60438 Frankfurt am Main, Germany.
| | - Werner Kühlbrandt
- Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, 60438 Frankfurt am Main, Germany.
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10
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Cryo EM structure of intact rotary H +-ATPase/synthase from Thermus thermophilus. Nat Commun 2018; 9:89. [PMID: 29311594 PMCID: PMC5758568 DOI: 10.1038/s41467-017-02553-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 12/04/2017] [Indexed: 12/27/2022] Open
Abstract
Proton translocating rotary ATPases couple ATP hydrolysis/synthesis, which occurs in the soluble domain, with proton flow through the membrane domain via a rotation of the common central rotor complex against the surrounding peripheral stator apparatus. Here, we present a large data set of single particle cryo-electron micrograph images of the V/A type H+-rotary ATPase from the bacterium Thermus thermophilus, enabling the identification of three rotational states based on the orientation of the rotor subunit. Using masked refinement and classification with signal subtractions, we obtain homogeneous reconstructions for the whole complexes and soluble V1 domains. These reconstructions are of higher resolution than any EM map of intact rotary ATPase reported previously, providing a detailed molecular basis for how the rotary ATPase maintains structural integrity of the peripheral stator apparatus, and confirming the existence of a clear proton translocation path from both sides of the membrane.
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11
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Abstract
Mitochondria are the power stations of the eukaryotic cell, using the energy released by the oxidation of glucose and other sugars to produce ATP. Electrons are transferred from NADH, produced in the citric acid cycle in the mitochondrial matrix, to oxygen by a series of large protein complexes in the inner mitochondrial membrane, which create a transmembrane electrochemical gradient by pumping protons across the membrane. The flow of protons back into the matrix via a proton channel in the ATP synthase leads to conformational changes in the nucleotide binding pockets and the formation of ATP. The three proton pumping complexes of the electron transfer chain are NADH-ubiquinone oxidoreductase or complex I, ubiquinone-cytochrome c oxidoreductase or complex III, and cytochrome c oxidase or complex IV. Succinate dehydrogenase or complex II does not pump protons, but contributes reduced ubiquinone. The structures of complex II, III and IV were determined by x-ray crystallography several decades ago, but complex I and ATP synthase have only recently started to reveal their secrets by advances in x-ray crystallography and cryo-electron microscopy. The complexes I, III and IV occur to a certain extent as supercomplexes in the membrane, the so-called respirasomes. Several hypotheses exist about their function. Recent cryo-electron microscopy structures show the architecture of the respirasome with near-atomic detail. ATP synthase occurs as dimers in the inner mitochondrial membrane, which by their curvature are responsible for the folding of the membrane into cristae and thus for the huge increase in available surface that makes mitochondria the efficient energy plants of the eukaryotic cell.
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Affiliation(s)
- Joana S Sousa
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Edoardo D'Imprima
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Janet Vonck
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
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12
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Affiliation(s)
- Chérif F. Matta
- Department
of Chemistry and Physics, Mount Saint Vincent University, Halifax, Nova Scotia B3M 2J6, Canada
- Department
of Chemistry, Dalhousie University, Halifax, Nova Scotia B3H 4J3, Canada
- Department
of Chemistry, Saint Mary’s University, Halifax, Nova Scotia B3H 3C3, Canada
- Département
de Chimie, Université Laval, Québec, Québec G1V 0A6, Canada
| | - Lou Massa
- Hunter
College and the Graduate School, City University of New York, New York, New York 10065, United States
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13
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Oligomeric Structure of Anabaena Sensory Rhodopsin in a Lipid Bilayer Environment by Combining Solid-State NMR and Long-range DEER Constraints. J Mol Biol 2017; 429:1903-1920. [DOI: 10.1016/j.jmb.2017.05.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 04/27/2017] [Accepted: 05/06/2017] [Indexed: 11/22/2022]
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14
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Punjani A, Brubaker MA, Fleet DJ. Building Proteins in a Day: Efficient 3D Molecular Structure Estimation with Electron Cryomicroscopy. IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE 2017; 39:706-718. [PMID: 27849524 DOI: 10.1109/tpami.2016.2627573] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Discovering the 3D atomic-resolution structure of molecules such as proteins and viruses is one of the foremost research problems in biology and medicine. Electron Cryomicroscopy (cryo-EM) is a promising vision-based technique for structure estimation which attempts to reconstruct 3D atomic structures from a large set of 2D transmission electron microscope images. This paper presents a new Bayesian framework for cryo-EM structure estimation that builds on modern stochastic optimization techniques to allow one to scale to very large datasets. We also introduce a novel Monte-Carlo technique that reduces the cost of evaluating the objective function during optimization by over five orders of magnitude. The net result is an approach capable of estimating 3D molecular structure from large-scale datasets in about a day on a single CPU workstation.
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15
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Davies RB, Smits C, Wong ASW, Stock D, Christie M, Sandin S, Stewart AG. Cryo-EM analysis of a domain antibody bound rotary ATPase complex. J Struct Biol 2017; 197:350-353. [PMID: 28115258 DOI: 10.1016/j.jsb.2017.01.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 01/16/2017] [Accepted: 01/17/2017] [Indexed: 01/11/2023]
Abstract
The bacterial A/V-type ATPase/synthase rotary motor couples ATP hydrolysis/synthesis with proton translocation across biological membranes. The A/V-type ATPase/synthase from Thermus thermophilus has been extensively studied both structurally and functionally for many years. Here we provide an 8.7Å resolution cryo-electron microscopy 3D reconstruction of this complex bound to single-domain antibody fragments, small monomeric antibodies containing just the variable heavy domain. Docking of known structures into the density revealed the molecular orientation of the domain antibodies, suggesting that structure determination of co-domain antibody:protein complexes could be a useful avenue for unstable or smaller proteins. Although previous studies suggested that the presence of fluoroaluminate in this complex could change the rotary state of this enzyme, we observed no gross structural rearrangements under these conditions.
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Affiliation(s)
- Roberta B Davies
- Molecular, Structural and Computational Biology Division, The Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia
| | - Callum Smits
- Molecular, Structural and Computational Biology Division, The Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia
| | - Andrew S W Wong
- NTU Institute of Structural Biology, Nanyang Technological University, 636921, Singapore
| | - Daniela Stock
- Molecular, Structural and Computational Biology Division, The Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; Faculty of Medicine, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Mary Christie
- Molecular, Structural and Computational Biology Division, The Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; Faculty of Medicine, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Sara Sandin
- NTU Institute of Structural Biology, Nanyang Technological University, 636921, Singapore; School of Biological Sciences, Nanyang Technological University, 637551, Singapore
| | - Alastair G Stewart
- Molecular, Structural and Computational Biology Division, The Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; Faculty of Medicine, The University of New South Wales, Sydney, NSW 2052, Australia.
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16
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In situ structure of trypanosomal ATP synthase dimer reveals a unique arrangement of catalytic subunits. Proc Natl Acad Sci U S A 2017; 114:992-997. [PMID: 28096380 DOI: 10.1073/pnas.1612386114] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
We used electron cryotomography and subtomogram averaging to determine the in situ structures of mitochondrial ATP synthase dimers from two organisms belonging to the phylum euglenozoa: Trypanosoma brucei, a lethal human parasite, and Euglena gracilis, a photosynthetic protist. At a resolution of 32.5 Å and 27.5 Å, respectively, the two structures clearly exhibit a noncanonical F1 head, in which the catalytic (αβ)3 assembly forms a triangular pyramid rather than the pseudo-sixfold ring arrangement typical of all other ATP synthases investigated so far. Fitting of known X-ray structures reveals that this unusual geometry results from a phylum-specific cleavage of the α subunit, in which the C-terminal αC fragments are displaced by ∼20 Å and rotated by ∼30° from their expected positions. In this location, the αC fragment is unable to form the conserved catalytic interface that was thought to be essential for ATP synthesis, and cannot convert γ-subunit rotation into the conformational changes implicit in rotary catalysis. The new arrangement of catalytic subunits suggests that the mechanism of ATP generation by rotary ATPases is less strictly conserved than has been generally assumed. The ATP synthases of these organisms present a unique model system for discerning the individual contributions of the α and β subunits to the fundamental process of ATP synthesis.
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17
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Hanazono Y, Takeda K, Miki K. Characterization of the Nqo5 subunit of bacterial complex I in the isolated state. FEBS Open Bio 2016; 6:687-95. [PMID: 27398308 PMCID: PMC4932448 DOI: 10.1002/2211-5463.12070] [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: 04/06/2016] [Revised: 04/12/2016] [Accepted: 04/14/2016] [Indexed: 11/09/2022] Open
Abstract
The subunits that comprise bacterial complex I (NADH:ubiquinone oxidoreductase) are also found in more complicated mitochondrial enzymes in eukaryotic organisms. Although the Nqo5 subunit is one of these conserved components and important for the formation of complex, it has been little studied. Here, we report structure analyses of isolated Nqo5 from Thermus thermophilus. Biochemical studies indicated that the C-terminal region following the 30-Kd subunit motif is disordered in the isolated state, while the remaining portion is already folded. Crystallographic studies of a trypsin-resistant fragment revealed detailed structural differences in the folded domain between the isolated and complexed states.
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Affiliation(s)
- Yuya Hanazono
- Department of Chemistry Graduate School of Science Kyoto University Sakyo-ku Kyoto Japan
| | - Kazuki Takeda
- Department of Chemistry Graduate School of Science Kyoto University Sakyo-ku Kyoto Japan; RIKEN SPring-8 Center at Harima Institute Sayo Hyogo Japan
| | - Kunio Miki
- Department of Chemistry Graduate School of Science Kyoto University Sakyo-ku Kyoto Japan; RIKEN SPring-8 Center at Harima Institute Sayo Hyogo Japan
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18
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Mazhab-Jafari MT, Rubinstein JL. Cryo-EM studies of the structure and dynamics of vacuolar-type ATPases. SCIENCE ADVANCES 2016; 2:e1600725. [PMID: 27532044 PMCID: PMC4985227 DOI: 10.1126/sciadv.1600725] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 06/15/2016] [Indexed: 06/06/2023]
Abstract
Electron cryomicroscopy (cryo-EM) has significantly advanced our understanding of molecular structure in biology. Recent innovations in both hardware and software have made cryo-EM a viable alternative for targets that are not amenable to x-ray crystallography or nuclear magnetic resonance (NMR) spectroscopy. Cryo-EM has even become the method of choice in some situations where x-ray crystallography and NMR spectroscopy are possible but where cryo-EM can determine structures at higher resolution or with less time or effort. Rotary adenosine triphosphatases (ATPases) are crucial to the maintenance of cellular homeostasis. These enzymes couple the synthesis or hydrolysis of adenosine triphosphate to the use or production of a transmembrane electrochemical ion gradient, respectively. However, the membrane-embedded nature and conformational heterogeneity of intact rotary ATPases have prevented their high-resolution structural analysis to date. Recent application of cryo-EM methods to the different types of rotary ATPase has led to sudden advances in understanding the structure and function of these enzymes, revealing significant conformational heterogeneity and characteristic transmembrane α helices that are highly tilted with respect to the membrane. In this Review, we will discuss what has been learned recently about rotary ATPase structure and function, with a particular focus on the vacuolar-type ATPases.
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Affiliation(s)
- Mohammad T. Mazhab-Jafari
- Molecular Structure and Function Program, The Hospital for Sick Children Research Institute, 686 Bay Street, Toronto, Ontario M5G 0A4, Canada
| | - John L. Rubinstein
- Molecular Structure and Function Program, The Hospital for Sick Children Research Institute, 686 Bay Street, Toronto, Ontario M5G 0A4, Canada
- Department of Biochemistry, The University of Toronto, 1 King’s College Circle, Toronto, Ontario M5S 1A8, Canada
- Department of Medical Biophysics, The University of Toronto, 101 College Street, Toronto, Ontario M5G 1L7, Canada
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19
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Papachristos K, Muench SP, Paci E. Characterization of the flexibility of the peripheral stalk of prokaryotic rotary A-ATPases by atomistic simulations. Proteins 2016; 84:1203-12. [PMID: 27177595 PMCID: PMC4988496 DOI: 10.1002/prot.25066] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 05/03/2016] [Accepted: 05/09/2016] [Indexed: 12/31/2022]
Abstract
Rotary ATPases are involved in numerous physiological processes, with the three distinct types (F/A/V‐ATPases) sharing functional properties and structural features. The basic mechanism involves the counter rotation of two motors, a soluble ATP hydrolyzing/synthesizing domain and a membrane‐embedded ion pump connected through a central rotor axle and a stator complex. Within the A/V‐ATPase family conformational flexibility of the EG stators has been shown to accommodate catalytic cycling and is considered to be important to function. For the A‐ATPase three EG structures have been reported, thought to represent conformational states of the stator during different stages of rotary catalysis. Here we use long, detailed atomistic simulations to show that those structures are conformers explored through thermal fluctuations, but do not represent highly populated states of the EG stator in solution. We show that the coiled coil tail domain has a high persistence length (∼100 nm), but retains the ability to adapt to different conformational states through the presence of two hinge regions. Moreover, the stator network of the related V‐ATPase has been suggested to adapt to subunit interactions in the collar region in addition to the nucleotide occupancy of the catalytic domain. The MD simulations reported here, reinforce this observation showing that the EG stators have enough flexibility to adapt to significantly different structural re‐arrangements and accommodate structural changes in the catalytic domain whilst resisting the large torque generated by catalytic cycling. These results are important to understand the role the stators play in the rotary‐ATPase mechanism. Proteins 2016; 84:1203–1212. © 2016 The Authors. Proteins: Structure, Function, and Bioinformatics Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Kostas Papachristos
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, England.,School of Molecular and Cellular Biology, University of Leeds, Leeds, England
| | - Stephen P Muench
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, England.,School of Biomedical Sciences, University of Leeds, Leeds, England
| | - Emanuele Paci
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, England.,School of Molecular and Cellular Biology, University of Leeds, Leeds, England
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20
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Cotter K, Stransky L, McGuire C, Forgac M. Recent Insights into the Structure, Regulation, and Function of the V-ATPases. Trends Biochem Sci 2016; 40:611-622. [PMID: 26410601 DOI: 10.1016/j.tibs.2015.08.005] [Citation(s) in RCA: 211] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 08/06/2015] [Accepted: 08/07/2015] [Indexed: 10/23/2022]
Abstract
The vacuolar (H(+))-ATPases (V-ATPases) are ATP-dependent proton pumps that acidify intracellular compartments and are also present at the plasma membrane. They function in such processes as membrane traffic, protein degradation, virus and toxin entry, bone resorption, pH homeostasis, and tumor cell invasion. V-ATPases are large multisubunit complexes, composed of an ATP-hydrolytic domain (V1) and a proton translocation domain (V0), and operate by a rotary mechanism. This review focuses on recent insights into their structure and mechanism, the mechanisms that regulate V-ATPase activity (particularly regulated assembly and trafficking), and the role of V-ATPases in processes such as cell signaling and cancer. These developments have highlighted the potential of V-ATPases as a therapeutic target in a variety of human diseases.
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Affiliation(s)
- Kristina Cotter
- Program in Cellular and Molecular Physiology, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA
| | - Laura Stransky
- Program in Cellular and Molecular Physiology, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA
| | - Christina McGuire
- Program in Biochemistry, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA
| | - Michael Forgac
- Program in Cellular and Molecular Physiology, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA; Program in Biochemistry, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA; Department of Developmental, Molecular, and Chemical Biology, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA.
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21
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Models for the a subunits of the Thermus thermophilus V/A-ATPase and Saccharomyces cerevisiae V-ATPase enzymes by cryo-EM and evolutionary covariance. Proc Natl Acad Sci U S A 2016; 113:3245-50. [PMID: 26951669 DOI: 10.1073/pnas.1521990113] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Rotary ATPases couple ATP synthesis or hydrolysis to proton translocation across a membrane. However, understanding proton translocation has been hampered by a lack of structural information for the membrane-embedded a subunit. The V/A-ATPase from the eubacterium Thermus thermophilus is similar in structure to the eukaryotic V-ATPase but has a simpler subunit composition and functions in vivo to synthesize ATP rather than pump protons. We determined the T. thermophilus V/A-ATPase structure by cryo-EM at 6.4 Å resolution. Evolutionary covariance analysis allowed tracing of the a subunit sequence within the map, providing a complete model of the rotary ATPase. Comparing the membrane-embedded regions of the T. thermophilus V/A-ATPase and eukaryotic V-ATPase from Saccharomyces cerevisiae allowed identification of the α-helices that belong to the a subunit and revealed the existence of previously unknown subunits in the eukaryotic enzyme. Subsequent evolutionary covariance analysis enabled construction of a model of the a subunit in the S. cerevisae V-ATPase that explains numerous biochemical studies of that enzyme. Comparing the two a subunit structures determined here with a structure of the distantly related a subunit from the bovine F-type ATP synthase revealed a conserved pattern of residues, suggesting a common mechanism for proton transport in all rotary ATPases.
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22
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Rawson S, Davies S, Lippiat JD, Muench SP. The changing landscape of membrane protein structural biology through developments in electron microscopy. Mol Membr Biol 2016; 33:12-22. [PMID: 27608730 PMCID: PMC5206964 DOI: 10.1080/09687688.2016.1221533] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 07/14/2016] [Accepted: 07/19/2016] [Indexed: 11/30/2022]
Abstract
Membrane proteins are ubiquitous in biology and are key targets for therapeutic development. Despite this, our structural understanding has lagged behind that of their soluble counterparts. This review provides an overview of this important field, focusing in particular on the recent resurgence of electron microscopy (EM) and the increasing role it has to play in the structural studies of membrane proteins, and illustrating this through several case studies. In addition, we examine some of the challenges remaining in structural determination, and what steps are underway to enhance our knowledge of these enigmatic proteins.
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Affiliation(s)
- Shaun Rawson
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds,
Leeds,
UK
| | - Simon Davies
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds,
Leeds,
UK
| | - Jonathan D. Lippiat
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds,
Leeds,
UK
| | - Stephen P. Muench
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds,
Leeds,
UK
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23
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Abstract
Despite diverse and changing extracellular environments, fungi maintain a relatively constant cytosolic pH and numerous organelles of distinct lumenal pH. Key players in fungal pH control are V-ATPases and the P-type proton pump Pma1. These two proton pumps act in concert with a large array of other transporters and are highly regulated. The activities of Pma1 and the V-ATPase are coordinated under some conditions, suggesting that pH in the cytosol and organelles is not controlled independently. Genomic studies, particularly in the highly tractable S. cerevisiae, are beginning to provide a systems-level view of pH control, including transcriptional responses to acid or alkaline ambient pH and definition of the full set of regulators required to maintain pH homeostasis. Genetically encoded pH sensors have provided new insights into localized mechanisms of pH control, as well as highlighting the dynamic nature of pH responses to the extracellular environment. Recent studies indicate that cellular pH plays a genuine signaling role that connects nutrient availability and growth rate through a number of mechanisms. Many of the pH control mechanisms found in S. cerevisiae are shared with other fungi, with adaptations for their individual physiological contexts. Fungi deploy certain proton transport and pH control mechanisms not shared with other eukaryotes; these regulators of cellular pH are potential antifungal targets. This review describes current and emerging knowledge proton transport and pH control mechanisms in S. cerevisiae and briefly discusses how these mechanisms vary among fungi.
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24
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Liu J, Fu X, Chang Z. A reciprocating motion-driven rotation mechanism for the ATP synthase. SCIENCE CHINA-LIFE SCIENCES 2015; 59:44-8. [DOI: 10.1007/s11427-015-4995-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 11/27/2015] [Indexed: 10/22/2022]
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25
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López-Blanco JR, Chacón P. New generation of elastic network models. Curr Opin Struct Biol 2015; 37:46-53. [PMID: 26716577 DOI: 10.1016/j.sbi.2015.11.013] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 11/23/2015] [Accepted: 11/26/2015] [Indexed: 12/16/2022]
Abstract
The intrinsic flexibility of proteins and nucleic acids can be grasped from remarkably simple mechanical models of particles connected by springs. In recent decades, Elastic Network Models (ENMs) combined with Normal Model Analysis widely confirmed their ability to predict biologically relevant motions of biomolecules and soon became a popular methodology to reveal large-scale dynamics in multiple structural biology scenarios. The simplicity, robustness, low computational cost, and relatively high accuracy are the reasons behind the success of ENMs. This review focuses on recent advances in the development and application of ENMs, paying particular attention to combinations with experimental data. Successful application scenarios include large macromolecular machines, structural refinement, docking, and evolutionary conservation.
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Affiliation(s)
- José Ramón López-Blanco
- Department of Biological Chemical Physics, Rocasolano Physical Chemistry Institute C.S.I.C., Serrano 119, 28006 Madrid, Spain
| | - Pablo Chacón
- Department of Biological Chemical Physics, Rocasolano Physical Chemistry Institute C.S.I.C., Serrano 119, 28006 Madrid, Spain.
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26
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Rosenthal PB. From high symmetry to high resolution in biological electron microscopy: a commentary on Crowther (1971) 'Procedures for three-dimensional reconstruction of spherical viruses by Fourier synthesis from electron micrographs'. Philos Trans R Soc Lond B Biol Sci 2015; 370:rstb.2014.0345. [PMID: 25750240 PMCID: PMC4360125 DOI: 10.1098/rstb.2014.0345] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Elucidation of the structure of biological macromolecules and larger assemblies has been essential to understanding the roles they play in living processes. Methods for three-dimensional structure determination of biological assemblies from images recorded in the electron microscope were therefore a key development. In his paper published in Philosophical Transactions B in 1971, Crowther described new computational procedures applied to the first three-dimensional reconstruction of an icosahedral virus from images of virus particles preserved in negative stain. The method for determining the relative orientation of randomly oriented particles and combining their images for reconstruction exploited the high symmetry of the virus particle. Computational methods for image analysis have since been extended to include biological assemblies without symmetry. Further experimental advances, combined with image analysis, have led to the method of cryomicroscopy, which is now used by structural biologists to study the structure and dynamics of biological machines and assemblies in atomic detail. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions of the Royal Society.
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Affiliation(s)
- Peter B Rosenthal
- Division of Physical Biochemistry, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
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27
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Kühlbrandt W, Davies KM. Rotary ATPases: A New Twist to an Ancient Machine. Trends Biochem Sci 2015; 41:106-116. [PMID: 26671611 DOI: 10.1016/j.tibs.2015.10.006] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 10/14/2015] [Accepted: 10/16/2015] [Indexed: 01/15/2023]
Abstract
Rotary ATPases are energy-converting nanomachines found in the membranes of all living organisms. The mechanism by which proton translocation through the membrane drives ATP synthesis, or how ATP hydrolysis generates a transmembrane proton gradient, has been unresolved for decades because the structure of a critical subunit in the membrane was unknown. Electron cryomicroscopy (cryoEM) studies of two rotary ATPases have now revealed a hairpin of long, horizontal, membrane-intrinsic α-helices in the a-subunit next to the c-ring rotor. The horizontal helices create a pair of aqueous half-channels in the membrane that provide access to the proton-binding sites in the rotor ring. These recent findings help to explain the highly conserved mechanism of ion translocation by rotary ATPases.
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Affiliation(s)
- Werner Kühlbrandt
- Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue Strasse 3, 60438 Frankfurt am Main, Germany.
| | - Karen M Davies
- Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue Strasse 3, 60438 Frankfurt am Main, Germany
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28
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Zhang XC, Liu M, Zhao Y. How does transmembrane electrochemical potential drive the rotation of Fo motor in an ATP synthase? Protein Cell 2015; 6:784-91. [PMID: 26472431 PMCID: PMC4624678 DOI: 10.1007/s13238-015-0217-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
While the field of ATP synthase research has a long history filled with landmark discoveries, recent structural works provide us with important insights into the mechanisms that links the proton movement with the rotation of the Fo motor. Here, we propose a mechanism of unidirectional rotation of the Fo complex, which is in agreement with these new structural insights as well as our more general ΔΨ-driving hypothesis of membrane proteins: A proton path in the rotor-stator interface is formed dynamically in concert with the rotation of the Fo rotor. The trajectory of the proton viewed in the reference system of the rotor (R-path) must lag behind that of the stator (S-path). The proton moves from a higher energy site to a lower site following both trajectories simultaneously. The two trajectories meet each other at the transient proton-binding site, resulting in a relative rotation between the rotor and stator. The kinetic energy of protons gained from ΔΨ is transferred to the c-ring as the protons are captured sequentially by the binding sites along the proton path, thus driving the unidirectional rotation of the c-ring. Our ΔΨ-driving hypothesis on Fo motor is an attempt to unveil the robust mechanism of energy conversion in the highly conserved, ubiquitously expressed rotary ATP synthases.
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Affiliation(s)
- Xuejun C. Zhang
- National Laboratory of Macromolecules, National Center of Protein Science-Beijing, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
| | - Min Liu
- National Laboratory of Macromolecules, National Center of Protein Science-Beijing, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
| | - Yan Zhao
- National Laboratory of Macromolecules, National Center of Protein Science-Beijing, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
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29
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De Zorzi R, Mi W, Liao M, Walz T. Single-particle electron microscopy in the study of membrane protein structure. Microscopy (Oxf) 2015; 65:81-96. [PMID: 26470917 DOI: 10.1093/jmicro/dfv058] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 09/20/2015] [Indexed: 01/13/2023] Open
Abstract
Single-particle electron microscopy (EM) provides the great advantage that protein structure can be studied without the need to grow crystals. However, due to technical limitations, this approach played only a minor role in the study of membrane protein structure. This situation has recently changed dramatically with the introduction of direct electron detection device cameras, which allow images of unprecedented quality to be recorded, also making software algorithms, such as three-dimensional classification and structure refinement, much more powerful. The enhanced potential of single-particle EM was impressively demonstrated by delivering the first long-sought atomic model of a member of the biomedically important transient receptor potential channel family. Structures of several more membrane proteins followed in short order. This review recounts the history of single-particle EM in the study of membrane proteins, describes the technical advances that now allow this approach to generate atomic models of membrane proteins and provides a brief overview of some of the membrane protein structures that have been studied by single-particle EM to date.
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Affiliation(s)
- Rita De Zorzi
- Department of Cell Biology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA Howard Hughes Medical Institute, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
| | - Wei Mi
- Department of Cell Biology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
| | - Maofu Liao
- Department of Cell Biology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
| | - Thomas Walz
- Department of Cell Biology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA Howard Hughes Medical Institute, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
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30
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Vinothkumar KR. Membrane protein structures without crystals, by single particle electron cryomicroscopy. Curr Opin Struct Biol 2015; 33:103-14. [PMID: 26435463 PMCID: PMC4764762 DOI: 10.1016/j.sbi.2015.07.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 07/13/2015] [Accepted: 07/24/2015] [Indexed: 11/25/2022]
Abstract
Electron microscopy of membrane proteins as single particles. Membrane protein structures without crystals. Direct electron detectors have high signal to noise. Medium to high-resolution structures of molecules between 0.13 and 2 MDa. Sub-tomogram averaging to study membrane proteins in situ.
It is an exciting period in membrane protein structural biology with a number of medically important protein structures determined at a rapid pace. However, two major hurdles still remain in the structural biology of membrane proteins. One is the inability to obtain large amounts of protein for crystallization and the other is the failure to get well-diffracting crystals. With single particle electron cryomicroscopy, both these problems can be overcome and high-resolution structures of membrane proteins and other labile protein complexes can be obtained with very little protein and without the need for crystals. In this review, I highlight recent advances in electron microscopy, detectors and software, which have allowed determination of medium to high-resolution structures of membrane proteins and complexes that have been difficult to study by other structural biological techniques.
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Affiliation(s)
- Kutti R Vinothkumar
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, United Kingdom.
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31
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GraDeR: Membrane Protein Complex Preparation for Single-Particle Cryo-EM. Structure 2015; 23:1769-1775. [DOI: 10.1016/j.str.2015.06.029] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 06/02/2015] [Accepted: 06/04/2015] [Indexed: 12/21/2022]
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32
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Electron cryomicroscopy observation of rotational states in a eukaryotic V-ATPase. Nature 2015; 521:241-5. [PMID: 25971514 DOI: 10.1038/nature14365] [Citation(s) in RCA: 214] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 03/05/2015] [Indexed: 01/19/2023]
Abstract
Eukaryotic vacuolar H(+)-ATPases (V-ATPases) are rotary enzymes that use energy from hydrolysis of ATP to ADP to pump protons across membranes and control the pH of many intracellular compartments. ATP hydrolysis in the soluble catalytic region of the enzyme is coupled to proton translocation through the membrane-bound region by rotation of a central rotor subcomplex, with peripheral stalks preventing the entire membrane-bound region from turning with the rotor. The eukaryotic V-ATPase is the most complex rotary ATPase: it has three peripheral stalks, a hetero-oligomeric proton-conducting proteolipid ring, several subunits not found in other rotary ATPases, and is regulated by reversible dissociation of its catalytic and proton-conducting regions. Studies of ATP synthases, V-ATPases, and bacterial/archaeal V/A-ATPases have suggested that flexibility is necessary for the catalytic mechanism of rotary ATPases, but the structures of different rotational states have never been observed experimentally. Here we use electron cryomicroscopy to obtain structures for three rotational states of the V-ATPase from the yeast Saccharomyces cerevisiae. The resulting series of structures shows ten proteolipid subunits in the c-ring, setting the ATP:H(+) ratio for proton pumping by the V-ATPase at 3:10, and reveals long and highly tilted transmembrane α-helices in the a-subunit that interact with the c-ring. The three different maps reveal the conformational changes that occur to couple rotation in the symmetry-mismatched soluble catalytic region to the membrane-bound proton-translocating region. Almost all of the subunits of the enzyme undergo conformational changes during the transitions between these three rotational states. The structures of these states provide direct evidence that deformation during rotation enables the smooth transmission of power through rotary ATPases.
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Abstract
Oxygenic photosynthesis is the principal converter of sunlight into chemical energy. Cyanobacteria and plants provide aerobic life with oxygen, food, fuel, fibers, and platform chemicals. Four multisubunit membrane proteins are involved: photosystem I (PSI), photosystem II (PSII), cytochrome b6f (cyt b6f), and ATP synthase (FOF1). ATP synthase is likewise a key enzyme of cell respiration. Over three billion years, the basic machinery of oxygenic photosynthesis and respiration has been perfected to minimize wasteful reactions. The proton-driven ATP synthase is embedded in a proton tight-coupling membrane. It is composed of two rotary motors/generators, FO and F1, which do not slip against each other. The proton-driven FO and the ATP-synthesizing F1 are coupled via elastic torque transmission. Elastic transmission decouples the two motors in kinetic detail but keeps them perfectly coupled in thermodynamic equilibrium and (time-averaged) under steady turnover. Elastic transmission enables operation with different gear ratios in different organisms.
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Affiliation(s)
- Wolfgang Junge
- Department of Biophysics, Universität Osnabrück, DE-49069 Osnabrück, Germany;
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34
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Iino R, Ueno H, Minagawa Y, Suzuki K, Murata T. Rotational mechanism of Enterococcus hirae V1-ATPase by crystal-structure and single-molecule analyses. Curr Opin Struct Biol 2015; 31:49-56. [PMID: 25796033 DOI: 10.1016/j.sbi.2015.02.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 02/03/2015] [Accepted: 02/23/2015] [Indexed: 11/25/2022]
Abstract
In ion-transporting rotary ATPases, the mechanical rotation of inner rotor subunits against other stator subunits in the complex mediates conversion of chemical free energy from ATP hydrolysis into electrochemical potential by pumping ions across the cell membrane. To fully understand the rotational mechanism of energy conversion, it is essential to analyze a target sample by multiple advanced methods that differ in spatiotemporal resolutions and sample environments. Here, we describe such a strategy applied to the water-soluble V1 moiety of Enterococcus hirae V-ATPase; this strategy involves integration of crystal structure studies and single-molecule analysis of rotary dynamics and torque generation. In addition, we describe our current model of the chemo-mechanical coupling scheme obtained by this approach, as well as future prospects.
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Affiliation(s)
- Ryota Iino
- Okazaki Institute for Integrative Bioscience, Institute for Molecular Science, National Institutes of Natural Sciences, Aichi 444-8787, Japan; Department of Functional Molecular Science, School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Kanagawa 240-0193, Japan.
| | - Hiroshi Ueno
- Department of Physics, Faculty of Science and Engineering, Chuo University, Tokyo 112-8551, Japan
| | - Yoshihiro Minagawa
- Department of Applied Chemistry, The University of Tokyo, Tokyo 113-8656, Japan
| | - Kano Suzuki
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba 263-8522, Japan
| | - Takeshi Murata
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba 263-8522, Japan; JST, PRESTO, Chiba 263-8522, Japan.
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35
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Nakanishi A, Kishikawa JI, Tamakoshi M, Yokoyama K. The ingenious structure of central rotor apparatus in VoV1; key for both complex disassembly and energy coupling between V1 and Vo. PLoS One 2015; 10:e0119602. [PMID: 25756791 PMCID: PMC4355294 DOI: 10.1371/journal.pone.0119602] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 01/14/2015] [Indexed: 11/25/2022] Open
Abstract
Vacuolar type rotary H+-ATPases (VoV1) couple ATP synthesis/hydrolysis by V1 with proton translocation by Vo via rotation of a central rotor apparatus composed of the V1-DF rotor shaft, a socket-like Vo-C (eukaryotic Vo-d) and the hydrophobic rotor ring. Reconstitution experiments using subcomplexes revealed a weak binding affinity of V1-DF to Vo-C despite the fact that torque needs to be transmitted between V1-DF and Vo-C for the tight energy coupling between V1 and Vo. Mutation of a short helix at the tip of V1-DF caused intramolecular uncoupling of VoV1, suggesting that proper fitting of the short helix of V1-D into the socket of Vo-C is required for tight energy coupling between V1 and Vo. To account for the apparently contradictory properties of the interaction between V1-DF and Vo-C (weak binding affinity but strict requirement for torque transmission), we propose a model in which the relationship between V1-DF and Vo-C corresponds to that between a slotted screwdriver and a head of slotted screw. This model is consistent with our previous result in which the central rotor apparatus is not the major factor for the association of V1 with Vo (Kishikawa and Yokoyama, J Biol Chem. 2012 24597-24603).
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Affiliation(s)
- Atsuko Nakanishi
- Department of Molecular Biosciences, Kyoto Sangyo University, Motoyama Kamigamo, Kita-ku, Kyoto, Japan
| | - Jun-ichi Kishikawa
- Department of Molecular Biosciences, Kyoto Sangyo University, Motoyama Kamigamo, Kita-ku, Kyoto, Japan
| | - Masatada Tamakoshi
- Department of Molecular Biology, Tokyo University of Pharmacy and Life Science, Horinouchi, Hachioji, Tokyo, Japan
| | - Ken Yokoyama
- Department of Molecular Biosciences, Kyoto Sangyo University, Motoyama Kamigamo, Kita-ku, Kyoto, Japan
- * E-mail:
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36
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Gloger C, Born AK, Antosch M, Müller V. The a subunit of the A1AO ATP synthase of Methanosarcina mazei Gö1 contains two conserved arginine residues that are crucial for ATP synthesis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:505-13. [PMID: 25724672 DOI: 10.1016/j.bbabio.2015.02.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 01/24/2015] [Accepted: 02/17/2015] [Indexed: 10/24/2022]
Abstract
Like the evolutionary related F1FO ATP synthases and V1VO ATPases, the A1AO ATP synthases from archaea are multisubunit, membrane-bound transport machines that couple ion flow to the synthesis of ATP. Although the subunit composition is known for at least two species, nothing is known so far with respect to the function of individual subunits or amino acid residues. To pave the road for a functional analysis of A1AO ATP synthases, we have cloned the entire operon from Methanosarcina mazei into an expression vector and produced the enzyme in Escherichia coli. Inverted membrane vesicles of the recombinants catalyzed ATP synthesis driven by NADH oxidation as well as artificial driving forces. [Formula: see text] as well as ΔpH were used as driving forces which is consistent with the inhibition of NADH-driven ATP synthesis by protonophores. Exchange of the conserved glutamate in subunit c led to a complete loss of ATP synthesis, proving that this residue is essential for H+ translocation. Exchange of two conserved arginine residues in subunit a has different effects on ATP synthesis. The role of these residues in ion translocation is discussed.
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Affiliation(s)
- Carolin Gloger
- Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe Universität Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
| | - Anna-Katharina Born
- Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe Universität Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
| | - Martin Antosch
- Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe Universität Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
| | - Volker Müller
- Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe Universität Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany.
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Horizontal membrane-intrinsic α-helices in the stator a-subunit of an F-type ATP synthase. Nature 2015; 521:237-40. [PMID: 25707805 DOI: 10.1038/nature14185] [Citation(s) in RCA: 200] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 12/29/2014] [Indexed: 12/12/2022]
Abstract
ATP, the universal energy currency of cells, is produced by F-type ATP synthases, which are ancient, membrane-bound nanomachines. F-type ATP synthases use the energy of a transmembrane electrochemical gradient to generate ATP by rotary catalysis. Protons moving across the membrane drive a rotor ring composed of 8-15 c-subunits. A central stalk transmits the rotation of the c-ring to the catalytic F1 head, where a series of conformational changes results in ATP synthesis. A key unresolved question in this fundamental process is how protons pass through the membrane to drive ATP production. Mitochondrial ATP synthases form V-shaped homodimers in cristae membranes. Here we report the structure of a native and active mitochondrial ATP synthase dimer, determined by single-particle electron cryomicroscopy at 6.2 Å resolution. Our structure shows four long, horizontal membrane-intrinsic α-helices in the a-subunit, arranged in two hairpins at an angle of approximately 70° relative to the c-ring helices. It has been proposed that a strictly conserved membrane-embedded arginine in the a-subunit couples proton translocation to c-ring rotation. A fit of the conserved carboxy-terminal a-subunit sequence places the conserved arginine next to a proton-binding c-subunit glutamate. The map shows a slanting solvent-accessible channel that extends from the mitochondrial matrix to the conserved arginine. Another hydrophilic cavity on the lumenal membrane surface defines a direct route for the protons to an essential histidine-glutamate pair. Our results provide unique new insights into the structure and function of rotary ATP synthases and explain how ATP production is coupled to proton translocation.
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Rawson S, Phillips C, Huss M, Tiburcy F, Wieczorek H, Trinick J, Harrison MA, Muench SP. Structure of the vacuolar H+-ATPase rotary motor reveals new mechanistic insights. Structure 2015; 23:461-471. [PMID: 25661654 PMCID: PMC4353692 DOI: 10.1016/j.str.2014.12.016] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2014] [Revised: 12/05/2014] [Accepted: 12/06/2014] [Indexed: 01/08/2023]
Abstract
Vacuolar H(+)-ATPases are multisubunit complexes that operate with rotary mechanics and are essential for membrane proton transport throughout eukaryotes. Here we report a ∼ 1 nm resolution reconstruction of a V-ATPase in a different conformational state from that previously reported for a lower-resolution yeast model. The stator network of the V-ATPase (and by implication that of other rotary ATPases) does not change conformation in different catalytic states, and hence must be relatively rigid. We also demonstrate that a conserved bearing in the catalytic domain is electrostatic, contributing to the extraordinarily high efficiency of rotary ATPases. Analysis of the rotor axle/membrane pump interface suggests how rotary ATPases accommodate different c ring stoichiometries while maintaining high efficiency. The model provides evidence for a half channel in the proton pump, supporting theoretical models of ion translocation. Our refined model therefore provides new insights into the structure and mechanics of the V-ATPases.
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Affiliation(s)
- Shaun Rawson
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Clair Phillips
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Markus Huss
- Abteilung Tierphysiologie, Fachbereich Biologie/Chemie, Universität Osnabrück, 49069 Osnabrück, Germany
| | - Felix Tiburcy
- Abteilung Tierphysiologie, Fachbereich Biologie/Chemie, Universität Osnabrück, 49069 Osnabrück, Germany
| | - Helmut Wieczorek
- Abteilung Tierphysiologie, Fachbereich Biologie/Chemie, Universität Osnabrück, 49069 Osnabrück, Germany
| | - John Trinick
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Michael A Harrison
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Stephen P Muench
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
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39
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Bueler SA, Rubinstein JL. Vma9p need not be associated with the yeast V-ATPase for fully-coupled proton pumping activity in vitro. Biochemistry 2015; 54:853-8. [PMID: 25546637 DOI: 10.1021/bi5013172] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Vacuolar-type ATPases (V-ATPases) acidify numerous intracellular compartments in all eukaryotic cells and are responsible for extracellular acidification in some specialized cells. V-ATPases are large macromolecular complexes with at least 15 different subunits, some of which are found in multiple copies. The main roles of all V-ATPase subunits have been established except for the e subunit, encoded by the gene VMA9 in Saccharomyces cerevisiae, and the Ac45 subunit, which is not found in the S. cerevisiae enzyme. Here we demonstrate that when the S. cerevisiae V-ATPase is solubilized with the detergent dodecylmaltoside (DDM), Vma9p is removed. We further demonstrate that after Vma9p has been removed by detergent the purified enzyme is still able to perform fully-coupled ATP-dependent proton pumping. This observation shows that Vma9p is not necessary in vitro for this principal activity of the V-ATPase.
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Affiliation(s)
- Stephanie A Bueler
- Molecular Structure and Function Program, The Hospital for Sick Children Research Institute , Toronto, Ontario M5G 1X8, Canada
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40
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Baker MR, Fan G, Serysheva II. Single-Particle Cryo-EM of the Ryanodine Receptor Channel in an Aqueous Environment. Eur J Transl Myol 2015; 25:4803. [PMID: 26913144 PMCID: PMC4748972 DOI: 10.4081/ejtm.2015.4803] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 12/22/2014] [Accepted: 12/31/2014] [Indexed: 12/31/2022] Open
Abstract
Ryanodine receptors (RyRs) are tetrameric ligand-gated Ca2+ release channels that are responsible for the increase of cytosolic Ca2+ concentration leading to muscle contraction. Our current understanding of RyR channel gating and regulation is greatly limited due to the lack of a high-resolution structure of the channel protein. The enormous size and unwieldy shape of Ca2+ release channels make X-ray or NMR methods difficult to apply for high-resolution structural analysis of the full-length functional channel. Single-particle electron cryo-microscopy (cryo-EM) is one of the only effective techniques for the study of such a large integral membrane protein and its molecular interactions. Despite recent developments in cryo-EM technologies and break-through single-particle cryo-EM studies of ion channels, cryospecimen preparation, particularly the presence of detergent in the buffer, remains the main impediment to obtaining atomic-resolution structures of ion channels and a multitude of other integral membrane protein complexes. In this review we will discuss properties of several detergents that have been successfully utilized in cryo-EM studies of ion channels and the emergence of the detergent alternative amphipol to stabilize ion channels for structure-function characterization. Future structural studies of challenging specimen like ion channels are likely to be facilitated by cryo-EM amenable detergents or alternative surfactants.
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Affiliation(s)
- Mariah R Baker
- Department of Biochemistry and Molecular Biology, The University of Texas Medical School at Houston, 6431 Fannin Street, Houston, TX 77030, USA
| | - Guizhen Fan
- Department of Biochemistry and Molecular Biology, The University of Texas Medical School at Houston, 6431 Fannin Street, Houston, TX 77030, USA
| | - Irina I Serysheva
- Department of Biochemistry and Molecular Biology, The University of Texas Medical School at Houston, 6431 Fannin Street, Houston, TX 77030, USA
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41
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Zhou A, Rohou A, Schep DG, Bason JV, Montgomery MG, Walker JE, Grigorieff N, Rubinstein JL. Structure and conformational states of the bovine mitochondrial ATP synthase by cryo-EM. eLife 2015; 4:e10180. [PMID: 26439008 PMCID: PMC4718723 DOI: 10.7554/elife.10180] [Citation(s) in RCA: 225] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 10/05/2015] [Indexed: 02/02/2023] Open
Abstract
Adenosine triphosphate (ATP), the chemical energy currency of biology, is synthesized in eukaryotic cells primarily by the mitochondrial ATP synthase. ATP synthases operate by a rotary catalytic mechanism where proton translocation through the membrane-inserted FO region is coupled to ATP synthesis in the catalytic F1 region via rotation of a central rotor subcomplex. We report here single particle electron cryomicroscopy (cryo-EM) analysis of the bovine mitochondrial ATP synthase. Combining cryo-EM data with bioinformatic analysis allowed us to determine the fold of the a subunit, suggesting a proton translocation path through the FO region that involves both the a and b subunits. 3D classification of images revealed seven distinct states of the enzyme that show different modes of bending and twisting in the intact ATP synthase. Rotational fluctuations of the c8-ring within the FO region support a Brownian ratchet mechanism for proton-translocation-driven rotation in ATP synthases.
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Affiliation(s)
- Anna Zhou
- The Hospital for Sick Children Research Institute, Toronto, Canada,Department of Medical Biophysics, The University of Toronto, Ontario, Canada
| | - Alexis Rohou
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Daniel G Schep
- The Hospital for Sick Children Research Institute, Toronto, Canada,Department of Medical Biophysics, The University of Toronto, Ontario, Canada
| | - John V Bason
- MRC Mitochondrial Biology Unit, Cambridge, United Kingdom
| | | | - John E Walker
- MRC Mitochondrial Biology Unit, Cambridge, United Kingdom, (JEW)
| | - Nikolaus Grigorieff
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States, (NG)
| | - John L Rubinstein
- The Hospital for Sick Children Research Institute, Toronto, Canada,Department of Medical Biophysics, The University of Toronto, Ontario, Canada,Department of Biochemistry, The University of Toronto, Ontario, Canada, (JLR)
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42
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Zhao J, Rubinstein JL. The study of vacuolar-type ATPases by single particle electron microscopy. Biochem Cell Biol 2014; 92:460-6. [DOI: 10.1139/bcb-2014-0086] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Nature’s molecular machines often work through the concerted action of many different protein subunits, which can give rise to large structures with complex activities. Vacuolar-type ATPases (V-ATPases) are membrane-embedded protein assemblies with a unique rotary catalytic mechanism. The dynamic nature and instability of V-ATPases make structural and functional studies of these enzymes challenging. Electron microscopy (EM) techniques, especially single particle electron cryomicroscopy (cryo-EM) and negative-stain EM, have provided extensive insight into the structure and function of these protein complexes. This minireview outlines what has been learned about V-ATPases using electron microscopy, highlights current challenges for their structural study, and discusses what cryo-EM will allow us to learn about these fascinating enzymes in the future.
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Affiliation(s)
- Jianhua Zhao
- The Hospital for Sick Children Research Institute, 686 Bay Street, Toronto, ON M5G 0A4, Canada
- Department of Medical Biophysics, The University of Toronto, 1 Kings College Circle, Toronto, ON M5S 1A8, Canada
| | - John L. Rubinstein
- The Hospital for Sick Children Research Institute, 686 Bay Street, Toronto, ON M5G 0A4, Canada
- Department of Medical Biophysics, The University of Toronto, 1 Kings College Circle, Toronto, ON M5S 1A8, Canada
- Department of Biochemistry, The University of Toronto, 101 College Street, Toronto, ON M5G 1L7, Canada
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43
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Richardson RA, Papachristos K, Read DJ, Harlen OG, Harrison M, Paci E, Muench SP, Harris SA. Understanding the apparent stator-rotor connections in the rotary ATPase family using coarse-grained computer modeling. Proteins 2014; 82:3298-311. [PMID: 25174610 DOI: 10.1002/prot.24680] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 07/14/2014] [Accepted: 08/06/2014] [Indexed: 11/12/2022]
Abstract
Advances in structural biology, such as cryo-electron microscopy (cryo-EM) have allowed for a number of sophisticated protein complexes to be characterized. However, often only a static snapshot of a protein complex is visualized despite the fact that conformational change is frequently inherent to biological function, as is the case for molecular motors. Computer simulations provide valuable insights into the different conformations available to a particular system that are not accessible using conventional structural techniques. For larger proteins and protein complexes, where a fully atomistic description would be computationally prohibitive, coarse-grained simulation techniques such as Elastic Network Modeling (ENM) are often employed, whereby each atom or group of atoms is linked by a set of springs whose properties can be customized according to the system of interest. Here we compare ENM with a recently proposed continuum model known as Fluctuating Finite Element Analysis (FFEA), which represents the biomolecule as a viscoelastic solid subject to thermal fluctuations. These two complementary computational techniques are used to answer a critical question in the rotary ATPase family; implicit within these motors is the need for a rotor axle and proton pump to rotate freely of the motor domain and stator structures. However, current single particle cryo-EM reconstructions have shown an apparent connection between the stators and rotor axle or pump region, hindering rotation. Both modeling approaches show a possible role for this connection and how it would significantly constrain the mobility of the rotary ATPase family.
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Affiliation(s)
- Robin A Richardson
- School of Physics and Astronomy, University of Leeds, Leeds, United Kingdom
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44
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Interacting cytoplasmic loops of subunits a and c of Escherichia coli F1F0 ATP synthase gate H+ transport to the cytoplasm. Proc Natl Acad Sci U S A 2014; 111:16730-5. [PMID: 25385585 DOI: 10.1073/pnas.1414660111] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
H(+)-transporting F1F0 ATP synthase catalyzes the synthesis of ATP via coupled rotary motors within F0 and F1. H(+) transport at the subunit a-c interface in transmembranous F0 drives rotation of a cylindrical c10 oligomer within the membrane, which is coupled to rotation of subunit γ within the α3β3 sector of F1 to mechanically drive ATP synthesis. F1F0 functions in a reversible manner, with ATP hydrolysis driving H(+) transport. ATP-driven H(+) transport in a select group of cysteine mutants in subunits a and c is inhibited after chelation of Ag(+) and/or Cd(+2) with the substituted sulfhydryl groups. The H(+) transport pathway mapped via these Ag(+)(Cd(+2))-sensitive Cys extends from the transmembrane helices (TMHs) of subunits a and c into cytoplasmic loops connecting the TMHs, suggesting these loop regions could be involved in gating H(+) release to the cytoplasm. Here, using select loop-region Cys from the single cytoplasmic loop of subunit c and multiple cytoplasmic loops of subunit a, we show that Cd(+2) directly inhibits passive H(+) transport mediated by F0 reconstituted in liposomes. Further, in extensions of previous studies, we show that the regions mediating passive H(+) transport can be cross-linked to each other. We conclude that the loop-regions in subunits a and c that are implicated in H(+) transport likely interact in a single structural domain, which then functions in gating H(+) release to the cytoplasm.
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45
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Rey M, Sarpe V, Burns KM, Buse J, Baker CAH, van Dijk M, Wordeman L, Bonvin AMJJ, Schriemer DC. Mass spec studio for integrative structural biology. Structure 2014; 22:1538-48. [PMID: 25242457 DOI: 10.1016/j.str.2014.08.013] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 07/30/2014] [Accepted: 08/06/2014] [Indexed: 02/01/2023]
Abstract
The integration of biophysical data from multiple sources is critical for developing accurate structural models of large multiprotein systems and their regulators. Mass spectrometry (MS) can be used to measure the insertion location for a wide range of topographically sensitive chemical probes, and such insertion data provide a rich, but disparate set of modeling restraints. We have developed a software platform that integrates the analysis of label-based MS and tandem MS (MS(2)) data with protein modeling activities (Mass Spec Studio). Analysis packages can mine any labeling data from any mass spectrometer in a proteomics-grade manner, and link labeling methods with data-directed protein interaction modeling using HADDOCK. Support is provided for hydrogen/deuterium exchange (HX) and covalent labeling chemistries, including novel acquisition strategies such as targeted HX-MS(2) and data-independent HX-MS(2). The latter permits the modeling of highly complex systems, which we demonstrate by the analysis of microtubule interactions.
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Affiliation(s)
- Martial Rey
- Department of Biochemistry and Molecular Biology and Southern Alberta Cancer Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Vladimir Sarpe
- Department of Biochemistry and Molecular Biology and Southern Alberta Cancer Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Kyle M Burns
- Department of Biochemistry and Molecular Biology and Southern Alberta Cancer Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Joshua Buse
- Department of Biochemistry and Molecular Biology and Southern Alberta Cancer Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | | | - Marc van Dijk
- Bijvoet Center for Biomolecular Research, Faculty of Science-Chemistry, Utrecht University, Padualaan 8, Utrecht CH 3584, the Netherlands
| | - Linda Wordeman
- Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, WA 98195-7290, USA
| | - Alexandre M J J Bonvin
- Bijvoet Center for Biomolecular Research, Faculty of Science-Chemistry, Utrecht University, Padualaan 8, Utrecht CH 3584, the Netherlands
| | - David C Schriemer
- Department of Biochemistry and Molecular Biology and Southern Alberta Cancer Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada.
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46
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López-Blanco JR, Chacón P. Structural modeling from electron microscopy data. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2014. [DOI: 10.1002/wcms.1199] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- José Ramón López-Blanco
- Department of Biological Physical Chemistry; Rocasolano Physical Chemistry Institute, CSIC; Madrid Spain
| | - Pablo Chacón
- Department of Biological Physical Chemistry; Rocasolano Physical Chemistry Institute, CSIC; Madrid Spain
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47
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Expression, purification and characterization of human vacuolar-type H+-ATPase subunit d1 and d2 in Escherichia coli. Protein Expr Purif 2014; 98:25-31. [DOI: 10.1016/j.pep.2014.03.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 02/27/2014] [Accepted: 03/01/2014] [Indexed: 11/20/2022]
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48
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Mayer F, Müller V. Adaptations of anaerobic archaea to life under extreme energy limitation. FEMS Microbiol Rev 2014; 38:449-72. [DOI: 10.1111/1574-6976.12043] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 08/30/2013] [Accepted: 09/03/2013] [Indexed: 11/28/2022] Open
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49
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Liao M, Cao E, Julius D, Cheng Y. Single particle electron cryo-microscopy of a mammalian ion channel. Curr Opin Struct Biol 2014; 27:1-7. [PMID: 24681231 DOI: 10.1016/j.sbi.2014.02.005] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 02/24/2014] [Accepted: 02/28/2014] [Indexed: 12/22/2022]
Abstract
The transient receptor potential (TRP) ion channel family is large and functionally diverse, second only to potassium channels. Despite their prominence within the animal kingdom, TRP channels have resisted crystallization and structural determination for many years. This barrier was recently broken when the three-dimensional structure of the vanilloid receptor 1 (TRPV1) was determined by single particle electron cryo-microscopy (cryo-EM). Moreover, this is the first example in which the near atomic resolution structure of an integral membrane protein was elucidated by this technique and in a manner not requiring crystals, demonstrating the transformative power of single particle cryo-EM for revealing high-resolution structures of integral membrane proteins, particularly those of mammalian origin. Here we summarize technical advances, in both biochemistry and cryo-EM, that led to this major breakthrough.
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Affiliation(s)
- Maofu Liao
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158-2517, USA
| | - Erhu Cao
- Department of Physiology, University of California, San Francisco, CA 94158-2517, USA
| | - David Julius
- Department of Physiology, University of California, San Francisco, CA 94158-2517, USA.
| | - Yifan Cheng
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158-2517, USA.
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50
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Grüber G, Manimekalai MSS, Mayer F, Müller V. ATP synthases from archaea: the beauty of a molecular motor. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:940-52. [PMID: 24650628 DOI: 10.1016/j.bbabio.2014.03.004] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 03/07/2014] [Accepted: 03/11/2014] [Indexed: 11/18/2022]
Abstract
Archaea live under different environmental conditions, such as high salinity, extreme pHs and cold or hot temperatures. How energy is conserved under such harsh environmental conditions is a major question in cellular bioenergetics of archaea. The key enzymes in energy conservation are the archaeal A1AO ATP synthases, a class of ATP synthases distinct from the F1FO ATP synthase ATP synthase found in bacteria, mitochondria and chloroplasts and the V1VO ATPases of eukaryotes. A1AO ATP synthases have distinct structural features such as a collar-like structure, an extended central stalk, and two peripheral stalks possibly stabilizing the A1AO ATP synthase during rotation in ATP synthesis/hydrolysis at high temperatures as well as to provide the storage of transient elastic energy during ion-pumping and ATP synthesis/-hydrolysis. High resolution structures of individual subunits and subcomplexes have been obtained in recent years that shed new light on the function and mechanism of this unique class of ATP synthases. An outstanding feature of archaeal A1AO ATP synthases is their diversity in size of rotor subunits and the coupling ion used for ATP synthesis with H(+), Na(+) or even H(+) and Na(+) using enzymes. The evolution of the H(+) binding site to a Na(+) binding site and its implications for the energy metabolism and physiology of the cell are discussed.
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Affiliation(s)
- Gerhard Grüber
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Republic of Singapore.
| | | | - Florian Mayer
- Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University Frankfurt/Main, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
| | - Volker Müller
- Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University Frankfurt/Main, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany.
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