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Sánchez-Vásquez L, Vázquez-Acevedo M, de la Mora J, Vega-deLuna F, Cardol P, Remacle C, Dreyfus G, González-Halphen D. Near-neighbor interactions of the membrane-embedded subunits of the mitochondrial ATP synthase of a chlorophycean alga. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2017; 1858:497-509. [DOI: 10.1016/j.bbabio.2017.04.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 04/25/2017] [Accepted: 04/29/2017] [Indexed: 12/24/2022]
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2
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Sánchez-Vásquez L, González-Halphen D. TOPOLOGÍA Y FUNCIÓN DE LAS SUBUNIDADES INTRÍNSECAS DE LA MEMBRANA DE LAS F 1 F O -ATP SINTASA MITOCONDRIALES. TIP REVISTA ESPECIALIZADA EN CIENCIAS QUÍMICO-BIOLÓGICAS 2017. [DOI: 10.1016/j.recqb.2017.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Hahn A, Parey K, Bublitz M, Mills DJ, Zickermann V, Vonck J, Kühlbrandt W, Meier T. Structure of a Complete ATP Synthase Dimer Reveals the Molecular Basis of Inner Mitochondrial Membrane Morphology. Mol Cell 2016; 63:445-56. [PMID: 27373333 PMCID: PMC4980432 DOI: 10.1016/j.molcel.2016.05.037] [Citation(s) in RCA: 199] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 04/21/2016] [Accepted: 05/26/2016] [Indexed: 11/28/2022]
Abstract
We determined the structure of a complete, dimeric F1Fo-ATP synthase from yeast Yarrowia lipolytica mitochondria by a combination of cryo-EM and X-ray crystallography. The final structure resolves 58 of the 60 dimer subunits. Horizontal helices of subunit a in Fo wrap around the c-ring rotor, and a total of six vertical helices assigned to subunits a, b, f, i, and 8 span the membrane. Subunit 8 (A6L in human) is an evolutionary derivative of the bacterial b subunit. On the lumenal membrane surface, subunit f establishes direct contact between the two monomers. Comparison with a cryo-EM map of the F1Fo monomer identifies subunits e and g at the lateral dimer interface. They do not form dimer contacts but enable dimer formation by inducing a strong membrane curvature of ∼100°. Our structure explains the structural basis of cristae formation in mitochondria, a landmark signature of eukaryotic cell morphology. Cryo-EM structure of a yeast F1Fo-ATP synthase dimer Inhibitor-free X-ray structure of the F1 head and rotor complex Mechanism of ATP generation by rotary catalysis Structural basis of cristae formation in the inner mitochondrial membrane
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Affiliation(s)
- Alexander Hahn
- Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue-Str. 3, 60438 Frankfurt am Main, Germany
| | - Kristian Parey
- Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue-Str. 3, 60438 Frankfurt am Main, Germany
| | - Maike Bublitz
- Institute of Biochemistry, Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt am Main, Germany
| | - Deryck J Mills
- Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue-Str. 3, 60438 Frankfurt am Main, Germany
| | - Volker Zickermann
- Institute of Biochemistry II, Medical School, Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt am Main, Germany
| | - Janet Vonck
- Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue-Str. 3, 60438 Frankfurt am Main, Germany
| | - Werner Kühlbrandt
- Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue-Str. 3, 60438 Frankfurt am Main, Germany.
| | - Thomas Meier
- Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue-Str. 3, 60438 Frankfurt am Main, Germany.
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Bernardi P, Rasola A, Forte M, Lippe G. The Mitochondrial Permeability Transition Pore: Channel Formation by F-ATP Synthase, Integration in Signal Transduction, and Role in Pathophysiology. Physiol Rev 2015; 95:1111-55. [PMID: 26269524 DOI: 10.1152/physrev.00001.2015] [Citation(s) in RCA: 419] [Impact Index Per Article: 46.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The mitochondrial permeability transition (PT) is a permeability increase of the inner mitochondrial membrane mediated by a channel, the permeability transition pore (PTP). After a brief historical introduction, we cover the key regulatory features of the PTP and provide a critical assessment of putative protein components that have been tested by genetic analysis. The discovery that under conditions of oxidative stress the F-ATP synthases of mammals, yeast, and Drosophila can be turned into Ca(2+)-dependent channels, whose electrophysiological properties match those of the corresponding PTPs, opens new perspectives to the field. We discuss structural and functional features of F-ATP synthases that may provide clues to its transition from an energy-conserving into an energy-dissipating device as well as recent advances on signal transduction to the PTP and on its role in cellular pathophysiology.
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Affiliation(s)
- Paolo Bernardi
- Department of Biomedical Sciences and Consiglio Nazionale delle Ricerche Neuroscience Institute, University of Padova, Padova, Italy; Vollum Institute, Oregon Health and Sciences University, Portland, Oregon; and Department of Food Science, University of Udine, Udine, Italy
| | - Andrea Rasola
- Department of Biomedical Sciences and Consiglio Nazionale delle Ricerche Neuroscience Institute, University of Padova, Padova, Italy; Vollum Institute, Oregon Health and Sciences University, Portland, Oregon; and Department of Food Science, University of Udine, Udine, Italy
| | - Michael Forte
- Department of Biomedical Sciences and Consiglio Nazionale delle Ricerche Neuroscience Institute, University of Padova, Padova, Italy; Vollum Institute, Oregon Health and Sciences University, Portland, Oregon; and Department of Food Science, University of Udine, Udine, Italy
| | - Giovanna Lippe
- Department of Biomedical Sciences and Consiglio Nazionale delle Ricerche Neuroscience Institute, University of Padova, Padova, Italy; Vollum Institute, Oregon Health and Sciences University, Portland, Oregon; and Department of Food Science, University of Udine, Udine, Italy
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ATP synthase oligomerization: From the enzyme models to the mitochondrial morphology. Int J Biochem Cell Biol 2013; 45:99-105. [DOI: 10.1016/j.biocel.2012.05.017] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2012] [Revised: 05/18/2012] [Accepted: 05/24/2012] [Indexed: 01/03/2023]
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Giraud MF, Paumard P, Sanchez C, Brèthes D, Velours J, Dautant A. Rotor architecture in the yeast and bovine F1-c-ring complexes of F-ATP synthase. J Struct Biol 2012; 177:490-7. [DOI: 10.1016/j.jsb.2011.10.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 10/07/2011] [Accepted: 10/27/2011] [Indexed: 11/16/2022]
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7
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Velours J, Stines-Chaumeil C, Habersetzer J, Chaignepain S, Dautant A, Brèthes D. Evidence of the proximity of ATP synthase subunits 6 (a) in the inner mitochondrial membrane and in the supramolecular forms of Saccharomyces cerevisiae ATP synthase. J Biol Chem 2011; 286:35477-35484. [PMID: 21868388 DOI: 10.1074/jbc.m111.275776] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The involvement of subunit 6 (a) in the interface between yeast ATP synthase monomers has been highlighted. Based on the formation of a disulfide bond and using the unique cysteine 23 as target, we show that two subunits 6 are close in the inner mitochondrial membrane and in the solubilized supramolecular forms of the yeast ATP synthase. In a null mutant devoid of supernumerary subunits e and g that are involved in the stabilization of ATP synthase dimers, ATP synthase monomers are close enough in the inner mitochondrial membrane to make a disulfide bridge between their subunits 6, and this proximity is maintained in detergent extract containing this enzyme. The cross-linking of cysteine 23 located in the N-terminal part of the first transmembrane helix of subunit 6 suggests that this membrane-spanning segment is in contact with its counterpart belonging to the ATP synthase monomer that faces it and participates in the monomer-monomer interface.
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Affiliation(s)
- Jean Velours
- CNRS, Institut de Biochimie et Génétique Cellulaires, UMR 5095; Université de Bordeaux, UMR 5095, 1 Rue Camille Saint Saëns, 33077 Bordeaux Cedex.
| | - Claire Stines-Chaumeil
- CNRS, Institut de Biochimie et Génétique Cellulaires, UMR 5095; Université de Bordeaux, UMR 5095, 1 Rue Camille Saint Saëns, 33077 Bordeaux Cedex
| | - Johan Habersetzer
- CNRS, Institut de Biochimie et Génétique Cellulaires, UMR 5095; Université de Bordeaux, UMR 5095, 1 Rue Camille Saint Saëns, 33077 Bordeaux Cedex
| | - Stéphane Chaignepain
- CNRS, Institut de Biochimie et Génétique Cellulaires, UMR 5095; Université de Bordeaux, UMR 5095, 1 Rue Camille Saint Saëns, 33077 Bordeaux Cedex; CNRS, Chimie et Biologie des Membranes et des Nanoobjets, UMR 5248, Allée de Saint Hilaire, Bât B14, 33600 Pessac, France
| | - Alain Dautant
- CNRS, Institut de Biochimie et Génétique Cellulaires, UMR 5095; Université de Bordeaux, UMR 5095, 1 Rue Camille Saint Saëns, 33077 Bordeaux Cedex
| | - Daniel Brèthes
- CNRS, Institut de Biochimie et Génétique Cellulaires, UMR 5095; Université de Bordeaux, UMR 5095, 1 Rue Camille Saint Saëns, 33077 Bordeaux Cedex.
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Devenish RJ, Prescott M, Rodgers AJW. The structure and function of mitochondrial F1F0-ATP synthases. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 267:1-58. [PMID: 18544496 DOI: 10.1016/s1937-6448(08)00601-1] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We review recent advances in understanding of the structure of the F(1)F(0)-ATP synthase of the mitochondrial inner membrane (mtATPase). A significant achievement has been the determination of the structure of the principal peripheral or stator stalk components bringing us closer to achieving the Holy Grail of a complete 3D structure for the complex. A major focus of the field in recent years has been to understand the physiological significance of dimers or other oligomer forms of mtATPase recoverable from membranes and their relationship to the structure of the cristae of the inner mitochondrial membrane. In addition, the association of mtATPase with other membrane proteins has been described and suggests that further levels of functional organization need to be considered. Many reports in recent years have concerned the location and function of ATP synthase complexes or its component subunits on the external surface of the plasma membrane. We consider whether the evidence supports complete complexes being located on the cell surface, the biogenesis of such complexes, and aspects of function especially related to the structure of mtATPase.
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Affiliation(s)
- Rodney J Devenish
- Department of Biochemistry and Molecular Biology, and ARC Centre of Excellence in Microbial Structural and Functional Genomics, Monash University, Clayton Campus, Victoria, 3800, Australia
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Zeng X, Neupert W, Tzagoloff A. The metalloprotease encoded by ATP23 has a dual function in processing and assembly of subunit 6 of mitochondrial ATPase. Mol Biol Cell 2006; 18:617-26. [PMID: 17135290 PMCID: PMC1783785 DOI: 10.1091/mbc.e06-09-0801] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
In the present study we have identified a new metalloprotease encoded by the nuclear ATP23 gene of Saccharomyces cerevisiae that is essential for expression of mitochondrial ATPase (F(1)-F(O) complex). Mutations in ATP23 cause the accumulation of the precursor form of subunit 6 and prevent assembly of F(O). Atp23p is associated with the mitochondrial inner membrane and is conserved from yeast to humans. A mutant harboring proteolytically inactive Atp23p accumulates the subunit 6 precursor but is nonetheless able to assemble a functional ATPase complex. These results indicate that removal of the subunit 6 presequence is not an essential event for ATPase biogenesis and that Atp23p, in addition to its processing activity, must provide another important function in F(O) assembly. The product of the yeast ATP10 gene was previously shown to interact with subunit 6 and to be required for its association with the subunit 9 ring. In this study one extra copy of ATP23 was found to be an effective suppressor of an atp10 null mutant, suggesting an overlap in the functions of Atp23p and Atp10p. Atp23p may, therefore, also be a chaperone, which in conjunction with Atp10p mediates the association of subunit 6 with the subunit 9 ring.
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Affiliation(s)
- Xiaomei Zeng
- *Department of Biological Sciences, Columbia University, New York, NY 10027; and
| | - Walter Neupert
- Adolf-Butenandt-Institut für Physiologische Chemie, Ludwig-Maximilians-Universität München, München 81377, Germany
| | - Alexander Tzagoloff
- *Department of Biological Sciences, Columbia University, New York, NY 10027; and
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Ackerman SH, Tzagoloff A. Function, structure, and biogenesis of mitochondrial ATP synthase. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 2005; 80:95-133. [PMID: 16164973 DOI: 10.1016/s0079-6603(05)80003-0] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Sharon H Ackerman
- Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA
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Stephens AN, Nagley P, Devenish RJ. Each yeast mitochondrial F1F0-ATP synthase complex contains a single copy of subunit 8. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2004; 1607:181-9. [PMID: 14670608 DOI: 10.1016/j.bbabio.2003.09.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The stoichiometry of subunit 8 in yeast mitochondrial F(1)F(0)-ATP synthase (mtATPase) has been evaluated using an immunoprecipitation approach. Single HA or FLAG epitopes were introduced at the N-terminus of subunit 8. Expression of each tagged subunit 8 variant in yeast cells lacking endogenous subunit 8 restored a respiratory phenotype and had little measurable effect on ATP hydrolase activity of the isolated enzyme. Moreover, the two epitope-tagged subunit 8 variants could be stably co-expressed in the same host cells and both of HA-Y8 and FLAG-Y8 could be detected in ATP synthase complexes isolated by native gel electrophoresis. Mitochondria isolated from each yeast strain were solubilized to release ATP synthase complexes in either the monomeric or dimeric forms. In each case, monoclonal antibodies directed against either the FLAG or HA epitope could immunoprecipitate intact ATP synthase complexes. When both HA-Y8 and FLAG-Y8 were co-expressed in cells, monomeric ATP synthases contained only a single subunit 8 variant after immunoprecipitation, corresponding to the particular antibody used (HA or FLAG). By contrast, both subunit 8 variants were recovered in samples of immunoprecipitated dimeric ATP synthase complexes, irrespective of the antibody used. We conclude that each monomeric yeast mitochondrial ATP synthase complex contains a single copy of subunit 8.
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Affiliation(s)
- Andrew N Stephens
- Department of Biochemistry and Molecular Biology, and ARC Centre for Structural and Functional Microbial Genomics, Monash University, Victoria 3800, Australia
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Stephens AN, Khan MA, Roucou X, Nagley P, Devenish RJ. The molecular neighborhood of subunit 8 of yeast mitochondrial F1F0-ATP synthase probed by cysteine scanning mutagenesis and chemical modification. J Biol Chem 2003; 278:17867-75. [PMID: 12626501 DOI: 10.1074/jbc.m300967200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The detailed membrane topography and neighboring polypeptides of subunit 8 in yeast mitochondrial ATP synthase have been determined using a combination of cysteine scanning mutagenesis and chemical modification. 46 single cysteine substitution mutants encompassing the length of the subunit 8 protein were constructed by site-directed mutagenesis. Expression of each cysteine variant in yeast lacking endogenous subunit 8 restored respiratory phenotype to cells and had little measurable effect on ATP hydrolase function. The exposure of each introduced cysteine residue to the aqueous environment was assessed in isolated mitochondria using the fluorescent thiol-modifying probe fluorescein 5-maleimide. The first 14 and last 13 amino acids of subunit 8 were accessible to fluorescein 5-maleimide in osmotically lysed mitochondria and are thus extrinsic to the lipid bilayer, indicating a 21-amino acid transmembrane span. The C-terminal region of subunit 8 was partially occluded by other ATP synthase subunits, especially in a small region surrounding Val-40 that was demonstrated to play an important role in maintaining the stability of the F(1)-F(0) interaction. Cross-linking using heterobifunctional reagents revealed the proximity of subunit 8 to subunits b, d, and f in the matrix and to subunits b, f, and 6 in the intermembrane space. A disulfide bridge was also formed between subunit 8(F7C) or (M10C) and residue Cys-23 of subunit 6, demonstrating a close interaction between these two hydrophobic membrane subunits and confirming the location of the N termini of each in the intermembrane space. We conclude that subunit 8 is an integral component of the stator stalk of yeast mitochondrial F(1)F(0)-ATP synthase.
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Affiliation(s)
- Andrew N Stephens
- Department of Biochemistry and Molecular Biology, Monash University, Clayton Campus, Victoria 3800, Australia
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Giraud MF, Paumard P, Soubannier V, Vaillier J, Arselin G, Salin B, Schaeffer J, Brèthes D, di Rago JP, Velours J. Is there a relationship between the supramolecular organization of the mitochondrial ATP synthase and the formation of cristae? BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1555:174-80. [PMID: 12206911 DOI: 10.1016/s0005-2728(02)00274-8] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Blue native polyacrylamide gel electrophoresis (BN-PAGE) analyses of detergent mitochondrial extracts have provided evidence that the yeast ATP synthase could form dimers. Cross-linking experiments performed on a modified version of the i-subunit of this enzyme indicate the existence of such ATP synthase dimers in the yeast inner mitochondrial membrane. We also show that the first transmembrane segment of the eukaryotic b-subunit (bTM1), like the two supernumerary subunits e and g, is required for dimerization/oligomerization of ATP synthases. Unlike mitochondria of wild-type cells that display a well-developed cristae network, mitochondria of yeast cells devoid of subunits e, g, or bTM1 present morphological alterations with an abnormal proliferation of the inner mitochondrial membrane. From these observations, we postulate that an anomalous organization of the inner mitochondrial membrane occurs due to the absence of ATP synthase dimers/oligomers. We provide a model in which the mitochondrial ATP synthase is a key element in cristae morphogenesis.
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Affiliation(s)
- Marie-France Giraud
- Institut de Biochimie et Génétique Cellulaires du CNRS, Université Victor Segalen, Bordeaux, France.
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Paumard P, Vaillier J, Coulary B, Schaeffer J, Soubannier V, Mueller DM, Brèthes D, di Rago JP, Velours J. The ATP synthase is involved in generating mitochondrial cristae morphology. EMBO J 2002; 21:221-30. [PMID: 11823415 PMCID: PMC125827 DOI: 10.1093/emboj/21.3.221] [Citation(s) in RCA: 581] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The inner membrane of the mitochondrion folds inwards, forming the cristae. This folding allows a greater amount of membrane to be packed into the mitochondrion. The data in this study demonstrate that subunits e and g of the mitochondrial ATP synthase are involved in generating mitochondrial cristae morphology. These two subunits are non-essential components of ATP synthase and are required for the dimerization and oligomerization of ATP synthase. Mitochondria of yeast cells deficient in either subunits e or g were found to have numerous digitations and onion-like structures that correspond to an uncontrolled biogenesis and/or folding of the inner mitochondrial membrane. The present data show that there is a link between dimerization of the mitochondrial ATP synthase and cristae morphology. A model is proposed of the assembly of ATP synthase dimers, taking into account the oligomerization of the yeast enzyme and earlier data on the ultrastructure of mitochondrial cristae, which suggests that the association of ATP synthase dimers is involved in the control of the biogenesis of the inner mitochondrial membrane.
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Affiliation(s)
| | | | | | | | | | - David M. Mueller
- Institut de Biochimie et Génétique Cellulaires du CNRS, Université Victor Ségalen, Bordeaux 2, 1 rue Camille Saint Saëns, 33077 Bordeaux cedex, France and
Department of Biochemistry and Molecular Biology, The Chicago Medical School, 3333 Greenbay Road, North Chicago, IL 60064, USA Corresponding author e-mail:
| | | | | | - Jean Velours
- Institut de Biochimie et Génétique Cellulaires du CNRS, Université Victor Ségalen, Bordeaux 2, 1 rue Camille Saint Saëns, 33077 Bordeaux cedex, France and
Department of Biochemistry and Molecular Biology, The Chicago Medical School, 3333 Greenbay Road, North Chicago, IL 60064, USA Corresponding author e-mail:
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Paul MF, Barrientos A, Tzagoloff A. A single amino acid change in subunit 6 of the yeast mitochondrial ATPase suppresses a null mutation in ATP10. J Biol Chem 2000; 275:29238-43. [PMID: 10867012 DOI: 10.1074/jbc.m004546200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In an earlier study, the ATP10 gene of Saccharomyces cerevisiae was shown to code for an inner membrane protein required for assembly of the F(0) sector of the mitochondrial ATPase complex (Ackerman, S., and Tzagoloff, A. (1990) J. Biol. Chem. 265, 9952-9959). To gain additional insights into the function of Atp10p, we have analyzed a revertant of an atp10 null mutant that displays partial recovery of oligomycin-sensitive ATPase and of respiratory competence. The suppressor mutation in the revertant has been mapped to the OLI2 locus in mitochondrial DNA and shown to be a single base change in the C-terminal coding region of the gene. The mutation results in the substitution of a valine for an alanine at residue 249 of subunit 6 of the ATPase. The ability of the subunit 6 mutation to compensate for the absence of Atp10p implies a functional interaction between the two proteins. Such an interaction is consistent with evidence indicating that the C-terminal region with the site of the mutation and the extramembrane domain of Atp10p are both on the matrix side of the inner membrane. Subunit 6 has been purified from the parental wild type strain, from the atp10 null mutant, and from the revertant. The N-terminal sequences of the three proteins indicated that they all start at Ser(11), the normal processing site of the subunit 6 precursor. Mass spectral analysis of the wild type and mutants subunit 6 failed to reveal any substantive difference of the wild type and mutant proteins when the mass of the latter was corrected for Ala --> Val mutation. These data argue against a role of Atp10p in post-translational modification of subunit 6. Although post-translational modification of another ATPase subunit interacting with subunit 6 cannot be excluded, a more likely function for Atp10p is that it acts as a subunit 6 chaperone during F(0) assembly.
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Affiliation(s)
- M F Paul
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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Abstract
The mitochondrial ATP synthase is a molecular motor that drives the phosphorylation of ADP to ATP. The yeast mitochondrial ATP synthase is composed of at least 19 different peptides, which comprise the F1 catalytic domain, the F0 proton pore, and two stalks, one of which is thought to act as a stator to link and hold F1 to F0, and the other as a rotor. Genetic studies using yeast Saccharomyces cerevisiae have suggested the hypothesis that the yeast mitochondrial ATP synthase can be assembled in the absence of 1, and even 2, of the polypeptides that are thought to comprise the rotor. However, the enzyme complex assembled in the absence of the rotor is thought to be uncoupled, allowing protons to freely flow through F0 into the mitochondrial matrix. Left uncontrolled, this is a lethal process and the cell must eliminate this leak if it is to survive. In yeast, the cell is thought to lose or delete its mitochondrial DNA (the petite mutation) thereby eliminating the genes encoding essential components of F0. Recent biochemical studies in yeast, and prior studies in E. coli, have provided support for the assembly of a partial ATP synthase in which the ATP synthase is no longer coupled to proton translocation.
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Affiliation(s)
- D M Mueller
- Department of Biochemistry and Molecular Biology, The Chicago Medical School, Illinois 60064, USA.
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Abstract
The ATP synthase of the yeast Saccharomyces cerevisiae is composed of 20 different subunits whose primary structure is known. The organization of proteins that constitute the membranous domain is now under investigation. Cysteine insertions combined with the use of nonpermeant maleimide reagents and cross-linking reagents showing different lengths and specificity contribute to the knowledge of the location of the N- and C-termini of the subunits involved in the stator of the enzyme and their organization. This review summarizes data on yeast ATP synthase obtained in our laboratory since 1980.
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Affiliation(s)
- J Velours
- Institut de Biochimie et Génétique Cellulaires du CNRS, Université Victor Ségalen, Bordeaux, France.
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