1
|
Hernansanz-Agustín P, Morales-Vidal C, Calvo E, Natale P, Martí-Mateos Y, Jaroszewicz SN, Cabrera-Alarcón JL, Acín-Pérez R, López-Montero I, Vázquez J, Enríquez JA. A transmitochondrial sodium gradient controls membrane potential in mammalian mitochondria. Cell 2024:S0092-8674(24)00974-7. [PMID: 39303716 DOI: 10.1016/j.cell.2024.08.045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 07/02/2024] [Accepted: 08/21/2024] [Indexed: 09/22/2024]
Abstract
Eukaryotic cell function and survival rely on the use of a mitochondrial H+ electrochemical gradient (Δp), which is composed of an inner mitochondrial membrane (IMM) potential (ΔΨmt) and a pH gradient (ΔpH). So far, ΔΨmt has been assumed to be composed exclusively of H+. Here, using a rainbow of mitochondrial and nuclear genetic models, we have discovered that a Na+ gradient equates with the H+ gradient and controls half of ΔΨmt in coupled-respiring mammalian mitochondria. This parallelism is controlled by the activity of the long-sought Na+-specific Na+/H+ exchanger (mNHE), which we have identified as the P-module of complex I (CI). Deregulation of this mNHE function, without affecting the canonical enzymatic activity or the assembly of CI, occurs in Leber's hereditary optic neuropathy (LHON), which has profound consequences in ΔΨmt and mitochondrial Ca2+ homeostasis and explains the previously unknown molecular pathogenesis of this neurodegenerative disease.
Collapse
Affiliation(s)
- Pablo Hernansanz-Agustín
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid 28029, Spain; Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable, Madrid, Spain.
| | - Carmen Morales-Vidal
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid 28029, Spain
| | - Enrique Calvo
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid 28029, Spain; Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBER-CV), Madrid, Spain
| | - Paolo Natale
- Departamento de Química-Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid (UCM), Madrid, Spain; Instituto de Investigación Biomédica Hospital Doce de Octubre (imas12), Madrid, Spain
| | - Yolanda Martí-Mateos
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid 28029, Spain
| | | | | | - Rebeca Acín-Pérez
- Department of Medicine, Endocrinology, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA
| | - Iván López-Montero
- Departamento de Química-Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid (UCM), Madrid, Spain; Instituto de Investigación Biomédica Hospital Doce de Octubre (imas12), Madrid, Spain; Instituto Pluridisciplinar-UCM, Madrid, Spain
| | - Jesús Vázquez
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid 28029, Spain; Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBER-CV), Madrid, Spain
| | - José Antonio Enríquez
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid 28029, Spain; Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable, Madrid, Spain.
| |
Collapse
|
2
|
Liang Y, Plourde A, Bueler SA, Liu J, Brzezinski P, Vahidi S, Rubinstein JL. Structure of mycobacterial respiratory complex I. Proc Natl Acad Sci U S A 2023; 120:e2214949120. [PMID: 36952383 PMCID: PMC10068793 DOI: 10.1073/pnas.2214949120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Accepted: 02/10/2023] [Indexed: 03/24/2023] Open
Abstract
Oxidative phosphorylation, the combined activity of the electron transport chain (ETC) and adenosine triphosphate synthase, has emerged as a valuable target for the treatment of infection by Mycobacterium tuberculosis and other mycobacteria. The mycobacterial ETC is highly branched with multiple dehydrogenases transferring electrons to a membrane-bound pool of menaquinone and multiple oxidases transferring electrons from the pool. The proton-pumping type I nicotinamide adenine dinucleotide (NADH) dehydrogenase (Complex I) is found in low abundance in the plasma membranes of mycobacteria in typical in vitro culture conditions and is often considered dispensable. We found that growth of Mycobacterium smegmatis in carbon-limited conditions greatly increased the abundance of Complex I and allowed isolation of a rotenone-sensitive preparation of the enzyme. Determination of the structure of the complex by cryoEM revealed the "orphan" two-component response regulator protein MSMEG_2064 as a subunit of the assembly. MSMEG_2064 in the complex occupies a site similar to the proposed redox-sensing subunit NDUFA9 in eukaryotic Complex I. An apparent purine nucleoside triphosphate within the NuoG subunit resembles the GTP-derived molybdenum cofactor in homologous formate dehydrogenase enzymes. The membrane region of the complex binds acyl phosphatidylinositol dimannoside, a characteristic three-tailed lipid from the mycobacterial membrane. The structure also shows menaquinone, which is preferentially used over ubiquinone by gram-positive bacteria, in two different positions along the quinone channel, comparable to ubiquinone in other structures and suggesting a conserved quinone binding mechanism.
Collapse
Affiliation(s)
- Yingke Liang
- Molecular Medicine Program, The Hospital for Sick Children, TorontoM5G 0A4, Canada
- Department of Biochemistry, University of Toronto, TorontoM5S 1A8, Canada
| | - Alicia Plourde
- Department of Molecular and Cellular Biology, University of Guelph, TorontoN1G 2W1, Canada
| | - Stephanie A. Bueler
- Molecular Medicine Program, The Hospital for Sick Children, TorontoM5G 0A4, Canada
| | - Jun Liu
- Department of Molecular Genetics, University of Toronto, TorontoM5S 1A8, Canada
| | - Peter Brzezinski
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91Stockholm, Sweden
| | - Siavash Vahidi
- Department of Molecular and Cellular Biology, University of Guelph, TorontoN1G 2W1, Canada
| | - John L. Rubinstein
- Molecular Medicine Program, The Hospital for Sick Children, TorontoM5G 0A4, Canada
- Department of Biochemistry, University of Toronto, TorontoM5S 1A8, Canada
- Department of Medical Biophysics, University of Toronto, TorontoM5G 1L7, Canada
| |
Collapse
|
3
|
Chung I, Grba DN, Wright JJ, Hirst J. Making the leap from structure to mechanism: are the open states of mammalian complex I identified by cryoEM resting states or catalytic intermediates? Curr Opin Struct Biol 2022; 77:102447. [PMID: 36087446 PMCID: PMC7614202 DOI: 10.1016/j.sbi.2022.102447] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 07/07/2022] [Accepted: 07/26/2022] [Indexed: 12/14/2022]
Abstract
Respiratory complex I (NADH:ubiquinone oxidoreductase) is a multi-subunit, energy-transducing mitochondrial enzyme that is essential for oxidative phosphorylation and regulating NAD+/NADH pools. Despite recent advances in structural knowledge and a long history of biochemical analyses, the mechanism of redox-coupled proton translocation by complex I remains unknown. Due to its ability to separate molecules in a mixed population into distinct classes, single-particle electron cryomicroscopy has enabled identification and characterisation of different complex I conformations. However, deciding on their catalytic and/or regulatory properties to underpin mechanistic hypotheses, especially without detailed biochemical characterisation of the structural samples, has proven challenging. In this review we explore different mechanistic interpretations of the closed and open states identified in cryoEM analyses of mammalian complex I.
Collapse
Affiliation(s)
- Injae Chung
- MRC Mitochondrial Biology Unit, University of Cambridge, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK
| | - Daniel N Grba
- MRC Mitochondrial Biology Unit, University of Cambridge, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK
| | - John J Wright
- MRC Mitochondrial Biology Unit, University of Cambridge, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK
| | - Judy Hirst
- MRC Mitochondrial Biology Unit, University of Cambridge, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK.
| |
Collapse
|
4
|
Qi B, Song L, Hu L, Guo D, Ren G, Peng T, Liu M, Fang Y, Li C, Zhang M, Li Y. Cardiac-specific overexpression of Ndufs1 ameliorates cardiac dysfunction after myocardial infarction by alleviating mitochondrial dysfunction and apoptosis. Exp Mol Med 2022; 54:946-960. [PMID: 35817848 PMCID: PMC9355970 DOI: 10.1038/s12276-022-00800-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 03/20/2022] [Accepted: 04/28/2022] [Indexed: 06/15/2023] Open
Abstract
Myocardial infarction (MI) is the leading cause of premature death among adults. Cardiomyocyte death and dysfunction of the remaining viable cardiomyocytes are the main pathological factors of heart failure after MI. Mitochondrial complexes are emerging as critical mediators for the regulation of cardiomyocyte function. However, the precise roles of mitochondrial complex subunits in heart failure after MI remain unclear. Here, we show that NADH:ubiquinone oxidoreductase core subunit S1 (Ndufs1) expression is decreased in the hearts of heart failure patients and mice with myocardial infarction. Furthermore, we found that cardiac-specific Ndufs1 overexpression alleviates cardiac dysfunction and myocardial fibrosis in the healing phase of MI. Our results demonstrated that Ndufs1 overexpression alleviates MI/hypoxia-induced ROS production and ROS-related apoptosis. Moreover, upregulation of Ndufs1 expression improved the reduced activity of complex I and impaired mitochondrial respiratory function caused by MI/hypoxia. Given that mitochondrial function and cardiomyocyte apoptosis are closely related to heart failure after MI, the results of this study suggest that targeting Ndufs1 may be a potential therapeutic strategy to improve cardiac function in patients with heart failure.
Collapse
Affiliation(s)
- Bingchao Qi
- Department of Cardiology, Tangdu Hospital, Fourth Military Medical University, Xi'an, 710038, People's Republic of China
| | - Liqiang Song
- Department of Pulmonary and Critical Care Medicine, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032, People's Republic of China
| | - Lang Hu
- Department of Cardiology, Tangdu Hospital, Fourth Military Medical University, Xi'an, 710038, People's Republic of China
| | - Dong Guo
- Department of Cardiology, Tangdu Hospital, Fourth Military Medical University, Xi'an, 710038, People's Republic of China
| | - Gaotong Ren
- Department of Cardiology, Tangdu Hospital, Fourth Military Medical University, Xi'an, 710038, People's Republic of China
| | - Tingwei Peng
- Department of Cardiology, Tangdu Hospital, Fourth Military Medical University, Xi'an, 710038, People's Republic of China
| | - Mingchuan Liu
- Department of Cardiology, Tangdu Hospital, Fourth Military Medical University, Xi'an, 710038, People's Republic of China
| | - Yexian Fang
- Department of Cardiology, Tangdu Hospital, Fourth Military Medical University, Xi'an, 710038, People's Republic of China
| | - Chunyu Li
- Department of Cardiology, Tangdu Hospital, Fourth Military Medical University, Xi'an, 710038, People's Republic of China
| | - Mingming Zhang
- Department of Cardiology, Tangdu Hospital, Fourth Military Medical University, Xi'an, 710038, People's Republic of China.
| | - Yan Li
- Department of Cardiology, Tangdu Hospital, Fourth Military Medical University, Xi'an, 710038, People's Republic of China.
| |
Collapse
|
5
|
Kampjut D, Sazanov LA. Structure of respiratory complex I – An emerging blueprint for the mechanism. Curr Opin Struct Biol 2022; 74:102350. [PMID: 35316665 PMCID: PMC7613608 DOI: 10.1016/j.sbi.2022.102350] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 01/25/2022] [Accepted: 02/08/2022] [Indexed: 11/26/2022]
Abstract
Complex I is one of the major respiratory complexes, conserved from bacteria to mammals. It oxidises NADH, reduces quinone and pumps protons across the membrane, thus playing a central role in the oxidative energy metabolism. In this review we discuss our current state of understanding the structure of complex I from various species of mammals, plants, fungi, and bacteria, as well as of several complex I-related proteins. By comparing the structural evidence from these systems in different redox states and data from mutagenesis and molecular simulations, we formulate the mechanisms of electron transfer and proton pumping and explain how they are conformationally and electrostatically coupled. Finally, we discuss the structural basis of the deactivation phenomenon in mammalian complex I.
Collapse
|
6
|
Padavannil A, Ayala-Hernandez MG, Castellanos-Silva EA, Letts JA. The Mysterious Multitude: Structural Perspective on the Accessory Subunits of Respiratory Complex I. Front Mol Biosci 2022; 8:798353. [PMID: 35047558 PMCID: PMC8762328 DOI: 10.3389/fmolb.2021.798353] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 11/25/2021] [Indexed: 01/10/2023] Open
Abstract
Complex I (CI) is the largest protein complex in the mitochondrial oxidative phosphorylation electron transport chain of the inner mitochondrial membrane and plays a key role in the transport of electrons from reduced substrates to molecular oxygen. CI is composed of 14 core subunits that are conserved across species and an increasing number of accessory subunits from bacteria to mammals. The fact that adding accessory subunits incurs costs of protein production and import suggests that these subunits play important physiological roles. Accordingly, knockout studies have demonstrated that accessory subunits are essential for CI assembly and function. Furthermore, clinical studies have shown that amino acid substitutions in accessory subunits lead to several debilitating and fatal CI deficiencies. Nevertheless, the specific roles of CI’s accessory subunits have remained mysterious. In this review, we explore the possible roles of each of mammalian CI’s 31 accessory subunits by integrating recent high-resolution CI structures with knockout, assembly, and clinical studies. Thus, we develop a framework of experimentally testable hypotheses for the function of the accessory subunits. We believe that this framework will provide inroads towards the complete understanding of mitochondrial CI physiology and help to develop strategies for the treatment of CI deficiencies.
Collapse
Affiliation(s)
- Abhilash Padavannil
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, United States
| | - Maria G Ayala-Hernandez
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, United States
| | - Eimy A Castellanos-Silva
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, United States
| | - James A Letts
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, United States
| |
Collapse
|
7
|
Structure and assembly of the mammalian mitochondrial supercomplex CIII 2CIV. Nature 2021; 598:364-367. [PMID: 34616041 DOI: 10.1038/s41586-021-03927-z] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 08/12/2021] [Indexed: 01/23/2023]
Abstract
The enzymes of the mitochondrial electron transport chain are key players of cell metabolism. Despite being active when isolated, in vivo they associate into supercomplexes1, whose precise role is debated. Supercomplexes CIII2CIV1-2 (refs. 2,3), CICIII2 (ref. 4) and CICIII2CIV (respirasome)5-10 exist in mammals, but in contrast to CICIII2 and the respirasome, to date the only known eukaryotic structures of CIII2CIV1-2 come from Saccharomyces cerevisiae11,12 and plants13, which have different organization. Here we present the first, to our knowledge, structures of mammalian (mouse and ovine) CIII2CIV and its assembly intermediates, in different conformations. We describe the assembly of CIII2CIV from the CIII2 precursor to the final CIII2CIV conformation, driven by the insertion of the N terminus of the assembly factor SCAF1 (ref. 14) deep into CIII2, while its C terminus is integrated into CIV. Our structures (which include CICIII2 and the respirasome) also confirm that SCAF1 is exclusively required for the assembly of CIII2CIV and has no role in the assembly of the respirasome. We show that CIII2 is asymmetric due to the presence of only one copy of subunit 9, which straddles both monomers and prevents the attachment of a second copy of SCAF1 to CIII2, explaining the presence of one copy of CIV in CIII2CIV in mammals. Finally, we show that CIII2 and CIV gain catalytic advantage when assembled into the supercomplex and propose a role for CIII2CIV in fine tuning the efficiency of electron transfer in the electron transport chain.
Collapse
|
8
|
Calisto F, Sousa FM, Sena FV, Refojo PN, Pereira MM. Mechanisms of Energy Transduction by Charge Translocating Membrane Proteins. Chem Rev 2021; 121:1804-1844. [PMID: 33398986 DOI: 10.1021/acs.chemrev.0c00830] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Life relies on the constant exchange of different forms of energy, i.e., on energy transduction. Therefore, organisms have evolved in a way to be able to harvest the energy made available by external sources (such as light or chemical compounds) and convert these into biological useable energy forms, such as the transmembrane difference of electrochemical potential (Δμ̃). Membrane proteins contribute to the establishment of Δμ̃ by coupling exergonic catalytic reactions to the translocation of charges (electrons/ions) across the membrane. Irrespectively of the energy source and consequent type of reaction, all charge-translocating proteins follow two molecular coupling mechanisms: direct- or indirect-coupling, depending on whether the translocated charge is involved in the driving reaction. In this review, we explore these two coupling mechanisms by thoroughly examining the different types of charge-translocating membrane proteins. For each protein, we analyze the respective reaction thermodynamics, electron transfer/catalytic processes, charge-translocating pathways, and ion/substrate stoichiometries.
Collapse
Affiliation(s)
- Filipa Calisto
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157, Oeiras, Portugal.,BioISI-Biosystems & Integrative Sciences Institute, University of Lisboa, Faculty of Sciences, Campo Grande, 1749-016 Lisboa, Portugal
| | - Filipe M Sousa
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157, Oeiras, Portugal.,BioISI-Biosystems & Integrative Sciences Institute, University of Lisboa, Faculty of Sciences, Campo Grande, 1749-016 Lisboa, Portugal
| | - Filipa V Sena
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157, Oeiras, Portugal.,BioISI-Biosystems & Integrative Sciences Institute, University of Lisboa, Faculty of Sciences, Campo Grande, 1749-016 Lisboa, Portugal
| | - Patricia N Refojo
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157, Oeiras, Portugal
| | - Manuela M Pereira
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157, Oeiras, Portugal.,BioISI-Biosystems & Integrative Sciences Institute, University of Lisboa, Faculty of Sciences, Campo Grande, 1749-016 Lisboa, Portugal
| |
Collapse
|
9
|
Kampjut D, Sazanov LA. The coupling mechanism of mammalian respiratory complex I. Science 2020; 370:science.abc4209. [PMID: 32972993 DOI: 10.1126/science.abc4209] [Citation(s) in RCA: 142] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 09/08/2020] [Indexed: 12/16/2022]
Abstract
Mitochondrial complex I couples NADH:ubiquinone oxidoreduction to proton pumping by an unknown mechanism. Here, we present cryo-electron microscopy structures of ovine complex I in five different conditions, including turnover, at resolutions up to 2.3 to 2.5 angstroms. Resolved water molecules allowed us to experimentally define the proton translocation pathways. Quinone binds at three positions along the quinone cavity, as does the inhibitor rotenone that also binds within subunit ND4. Dramatic conformational changes around the quinone cavity couple the redox reaction to proton translocation during open-to-closed state transitions of the enzyme. In the induced deactive state, the open conformation is arrested by the ND6 subunit. We propose a detailed molecular coupling mechanism of complex I, which is an unexpected combination of conformational changes and electrostatic interactions.
Collapse
Affiliation(s)
- Domen Kampjut
- IST Austria, Am Campus 1, 3400 Klosterneuburg, Austria
| | | |
Collapse
|
10
|
Cryo-EM structure of the entire mammalian F-type ATP synthase. Nat Struct Mol Biol 2020; 27:1077-1085. [DOI: 10.1038/s41594-020-0503-8] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 08/06/2020] [Indexed: 02/07/2023]
|
11
|
Ni Y, Hagras MA, Konstantopoulou V, Mayr JA, Stuchebrukhov AA, Meierhofer D. Mutations in NDUFS1 Cause Metabolic Reprogramming and Disruption of the Electron Transfer. Cells 2019; 8:cells8101149. [PMID: 31557978 PMCID: PMC6829531 DOI: 10.3390/cells8101149] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 09/10/2019] [Accepted: 09/20/2019] [Indexed: 01/07/2023] Open
Abstract
Complex I (CI) is the first enzyme of the mitochondrial respiratory chain and couples the electron transfer with proton pumping. Mutations in genes encoding CI subunits can frequently cause inborn metabolic errors. We applied proteome and metabolome profiling of patient-derived cells harboring pathogenic mutations in two distinct CI genes to elucidate underlying pathomechanisms on the molecular level. Our results indicated that the electron transfer within CI was interrupted in both patients by different mechanisms. We showed that the biallelic mutations in NDUFS1 led to a decreased stability of the entire N-module of CI and disrupted the electron transfer between two iron–sulfur clusters. Strikingly interesting and in contrast to the proteome, metabolome profiling illustrated that the pattern of dysregulated metabolites was almost identical in both patients, such as the inhibitory feedback on the TCA cycle and altered glutathione levels, indicative for reactive oxygen species (ROS) stress. Our findings deciphered pathological mechanisms of CI deficiency to better understand inborn metabolic errors.
Collapse
Affiliation(s)
- Yang Ni
- Mass Spectrometry Facility, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany;
- Department of Biology, Chemistry and Pharmacy, Freie Universität Berlin, 14195 Berlin, Germany
- Present address: Laboratory of Angiogenesis and Vascular Metabolism, VIB-KU Leuven Center for Cancer Biology, 3000 Leuven, Belgium
| | - Muhammad A. Hagras
- Department of Chemistry, University of California Davis, Davis, CA 95616, USA; (M.A.H.); (A.A.S.)
- Present address: Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Vassiliki Konstantopoulou
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, 1090 Vienna, Austria;
| | - Johannes A. Mayr
- Department of Pediatrics, Paracelsus Medical University Salzburg, 5020 Salzburg, Austria;
| | - Alexei A. Stuchebrukhov
- Department of Chemistry, University of California Davis, Davis, CA 95616, USA; (M.A.H.); (A.A.S.)
| | - David Meierhofer
- Mass Spectrometry Facility, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany;
- Correspondence: ; Tel.: +49-30-8413-1567
| |
Collapse
|
12
|
Letts JA, Fiedorczuk K, Degliesposti G, Skehel M, Sazanov LA. Structures of Respiratory Supercomplex I+III 2 Reveal Functional and Conformational Crosstalk. Mol Cell 2019; 75:1131-1146.e6. [PMID: 31492636 PMCID: PMC6926478 DOI: 10.1016/j.molcel.2019.07.022] [Citation(s) in RCA: 124] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 06/10/2019] [Accepted: 07/15/2019] [Indexed: 11/02/2022]
Abstract
The mitochondrial electron transport chain complexes are organized into supercomplexes (SCs) of defined stoichiometry, which have been proposed to regulate electron flux via substrate channeling. We demonstrate that CoQ trapping in the isolated SC I+III2 limits complex (C)I turnover, arguing against channeling. The SC structure, resolved at up to 3.8 Å in four distinct states, suggests that CoQ oxidation may be rate limiting because of unequal access of CoQ to the active sites of CIII2. CI shows a transition between "closed" and "open" conformations, accompanied by the striking rotation of a key transmembrane helix. Furthermore, the state of CI affects the conformational flexibility within CIII2, demonstrating crosstalk between the enzymes. CoQ was identified at only three of the four binding sites in CIII2, suggesting that interaction with CI disrupts CIII2 symmetry in a functionally relevant manner. Together, these observations indicate a more nuanced functional role for the SCs.
Collapse
Affiliation(s)
- James A Letts
- Institute of Science and Technology Austria, Klosterneuberg 3400, Austria; Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA
| | - Karol Fiedorczuk
- Institute of Science and Technology Austria, Klosterneuberg 3400, Austria; Laboratory of Membrane Biophysics and Biology, The Rockefeller University, New York, NY 10065, USA
| | | | - Mark Skehel
- MRC Laboratory of Molecular Biology, Cambridge CB2 OQH, UK
| | - Leonid A Sazanov
- Institute of Science and Technology Austria, Klosterneuberg 3400, Austria.
| |
Collapse
|
13
|
Kampjut D, Sazanov LA. Structure and mechanism of mitochondrial proton-translocating transhydrogenase. Nature 2019; 573:291-295. [PMID: 31462775 DOI: 10.1038/s41586-019-1519-2] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 07/31/2019] [Indexed: 11/09/2022]
Abstract
Proton-translocating transhydrogenase (also known as nicotinamide nucleotide transhydrogenase (NNT)) is found in the plasma membranes of bacteria and the inner mitochondrial membranes of eukaryotes. NNT catalyses the transfer of a hydride between NADH and NADP+, coupled to the translocation of one proton across the membrane. Its main physiological function is the generation of NADPH, which is a substrate in anabolic reactions and a regulator of oxidative status; however, NNT may also fine-tune the Krebs cycle1,2. NNT deficiency causes familial glucocorticoid deficiency in humans and metabolic abnormalities in mice, similar to those observed in type II diabetes3,4. The catalytic mechanism of NNT has been proposed to involve a rotation of around 180° of the entire NADP(H)-binding domain that alternately participates in hydride transfer and proton-channel gating. However, owing to the lack of high-resolution structures of intact NNT, the details of this process remain unclear5,6. Here we present the cryo-electron microscopy structure of intact mammalian NNT in different conformational states. We show how the NADP(H)-binding domain opens the proton channel to the opposite sides of the membrane, and we provide structures of these two states. We also describe the catalytically important interfaces and linkers between the membrane and the soluble domains and their roles in nucleotide exchange. These structures enable us to propose a revised mechanism for a coupling process in NNT that is consistent with a large body of previous biochemical work. Our results are relevant to the development of currently unavailable NNT inhibitors, which may have therapeutic potential in ischaemia reperfusion injury, metabolic syndrome and some cancers7-9.
Collapse
Affiliation(s)
- Domen Kampjut
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Leonid A Sazanov
- Institute of Science and Technology Austria, Klosterneuburg, Austria.
| |
Collapse
|
14
|
Uno S, Kimura H, Murai M, Miyoshi H. Exploring the quinone/inhibitor-binding pocket in mitochondrial respiratory complex I by chemical biology approaches. J Biol Chem 2018; 294:679-696. [PMID: 30425100 DOI: 10.1074/jbc.ra118.006056] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 11/10/2018] [Indexed: 11/06/2022] Open
Abstract
NADH-quinone oxidoreductase (respiratory complex I) couples NADH-to-quinone electron transfer to the translocation of protons across the membrane. Even though the architecture of the quinone-access channel in the enzyme has been modeled by X-ray crystallography and cryo-EM, conflicting findings raise the question whether the models fully reflect physiologically relevant states present throughout the catalytic cycle. To gain further insights into the structural features of the binding pocket for quinone/inhibitor, we performed chemical biology experiments using bovine heart sub-mitochondrial particles. We synthesized ubiquinones that are oversized (SF-UQs) or lipid-like (PC-UQs) and are highly unlikely to enter and transit the predicted narrow channel. We found that SF-UQs and PC-UQs can be catalytically reduced by complex I, albeit only at moderate or low rates. Moreover, quinone-site inhibitors completely blocked the catalytic reduction and the membrane potential formation coupled to this reduction. Photoaffinity-labeling experiments revealed that amiloride-type inhibitors bind to the interfacial domain of multiple core subunits (49 kDa, ND1, and PSST) and the 39-kDa supernumerary subunit, although the latter does not make up the channel cavity in the current models. The binding of amilorides to the multiple target subunits was remarkably suppressed by other quinone-site inhibitors and SF-UQs. Taken together, the present results are difficult to reconcile with the current channel models. On the basis of comprehensive interpretations of the present results and of previous findings, we discuss the physiological relevance of these models.
Collapse
Affiliation(s)
- Shinpei Uno
- From the Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Hironori Kimura
- From the Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Masatoshi Murai
- From the Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Hideto Miyoshi
- From the Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| |
Collapse
|
15
|
Fiedorczuk K, Sazanov LA. Mammalian Mitochondrial Complex I Structure and Disease-Causing Mutations. Trends Cell Biol 2018; 28:835-867. [PMID: 30055843 DOI: 10.1016/j.tcb.2018.06.006] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 06/14/2018] [Accepted: 06/22/2018] [Indexed: 12/31/2022]
Abstract
Complex I has an essential role in ATP production by coupling electron transfer from NADH to quinone with translocation of protons across the inner mitochondrial membrane. Isolated complex I deficiency is a frequent cause of mitochondrial inherited diseases. Complex I has also been implicated in cancer, ageing, and neurodegenerative conditions. Until recently, the understanding of complex I deficiency on the molecular level was limited due to the lack of high-resolution structures of the enzyme. However, due to developments in single particle cryo-electron microscopy (cryo-EM), recent studies have reported nearly atomic resolution maps and models of mitochondrial complex I. These structures significantly add to our understanding of complex I mechanism and assembly. The disease-causing mutations are discussed here in their structural context.
Collapse
Affiliation(s)
- Karol Fiedorczuk
- Institute of Science and Technology Austria, Am Campus 1, Klosterneuburg 3400, Austria; Present address: The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Leonid A Sazanov
- Institute of Science and Technology Austria, Am Campus 1, Klosterneuburg 3400, Austria.
| |
Collapse
|
16
|
Gladyshev GV, Grivennikova VG, Vinogradov AD. FMN site-independent energy-linked reverse electron transfer in mitochondrial respiratory complex I. FEBS Lett 2018; 592:2213-2219. [PMID: 29851085 DOI: 10.1002/1873-3468.13117] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 05/16/2018] [Accepted: 05/17/2018] [Indexed: 11/06/2022]
Abstract
A simple assay procedure for measuring ATP-dependent reverse electron transfer from ubiquinol to hexaammineruthenium (III) (HAR) catalyzed by mitochondrial respiratory complex I is introduced. The specific activity of the enzyme in this reaction and its sensitivity to the standard inhibitors and uncoupling are the same as with other well-known electron acceptors, NAD+ and ferricyanide. In contrast to the reactions with these acceptors, the energy-dependent HAR reduction is not inhibited by NADH-OH, the specific inhibitor of NADH-binding site. These results suggest that a catalytically competent electron connection exists between HAR and a redox component of complex I that is different from flavin mononucleotide bound at the substrate-binding site.
Collapse
Affiliation(s)
- Grigory V Gladyshev
- Department of Biochemistry, School of Biology, Moscow State University, Russia
| | - Vera G Grivennikova
- Department of Biochemistry, School of Biology, Moscow State University, Russia
| | - Andrei D Vinogradov
- Department of Biochemistry, School of Biology, Moscow State University, Russia
| |
Collapse
|
17
|
Bundgaard A, James AM, Joyce W, Murphy MP, Fago A. Suppression of reactive oxygen species generation in heart mitochondria from anoxic turtles: the role of complex I S-nitrosation. J Exp Biol 2018; 221:jeb174391. [PMID: 29496783 PMCID: PMC5963835 DOI: 10.1242/jeb.174391] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 02/26/2018] [Indexed: 12/12/2022]
Abstract
Freshwater turtles (Trachemys scripta) are among the very few vertebrates capable of tolerating severe hypoxia and re-oxygenation without suffering from damage to the heart. As myocardial ischemia and reperfusion causes a burst of mitochondrial reactive oxygen species (ROS) in mammals, the question arises as to whether, and if so how, this ROS burst is prevented in the turtle heart. We find that heart mitochondria isolated from turtles acclimated to anoxia produce less ROS than mitochondria from normoxic turtles when consuming succinate. As succinate accumulates in the hypoxic heart and is oxidized when oxygen returns, this suggests an adaptation to lessen ROS production. Specific S-nitrosation of complex I can lower ROS in mammals and here we show that turtle complex I activity and ROS production can also be strongly depressed in vitro by S-nitrosation. We detect in vivo endogenous S-nitrosated complex I in turtle heart mitochondria, but these levels are unaffected upon anoxia acclimation. Thus, while heart mitochondria from anoxia-acclimated turtles generate less ROS and have a lower aerobic capacity than those from normoxic turtles, this is not due to decreases in complex I activity or expression levels. Interestingly, in-gel activity staining reveals that most complex I of heart mitochondria from normoxic and anoxic turtles forms stable super-complexes with other respiratory enzymes and, in contrast to mammals, these are not disrupted by dodecyl maltoside. Taken together, these results show that although S-nitrosation of complex I is a potent mechanism to prevent ROS formation upon re-oxygenation after anoxia in vitro, this is not a major cause of the suppression of ROS production by anoxic turtle heart mitochondria.
Collapse
Affiliation(s)
- Amanda Bundgaard
- Department of Biosciences, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Andrew M James
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, CB2 0XY, UK
| | - William Joyce
- Department of Biosciences, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Michael P Murphy
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, CB2 0XY, UK
| | - Angela Fago
- Department of Biosciences, Aarhus University, DK-8000 Aarhus C, Denmark
| |
Collapse
|
18
|
Shimada S, Maeda S, Hikita M, Mieda-Higa K, Uene S, Nariai Y, Shinzawa-Itoh K. Solubilization conditions for bovine heart mitochondrial membranes allow selective purification of large quantities of respiratory complexes I, III, and V. Protein Expr Purif 2018; 150:33-43. [PMID: 29702187 DOI: 10.1016/j.pep.2018.04.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 04/20/2018] [Accepted: 04/23/2018] [Indexed: 11/28/2022]
Abstract
Ascertaining the structure and functions of mitochondrial respiratory chain complexes is essential to understanding the biological mechanisms of energy conversion; therefore, numerous studies have examined these complexes. A fundamental part of that research involves devising a method for purifying samples with good reproducibility; the samples obtained need to be stable and their constituents need to retain the same structure and functions they possess when in mitochondrial membranes. Submitochondrial bovine heart particles were isolated using differential centrifugation to adjust to a membrane concentration of 46.0% (w/v) or 31.5% (w/v) based on weight. After 0.7% (w/v) deoxycholic acid, 0.4% (w/v) decyl maltoside, and 7.2% (w/v) potassium chloride were added to the mitochondrial membranes, those membranes were solubilized. At a membrane concentration of 46%, complex V was selectively solubilized, whereas at a concentration of 31.5% (w/v), complexes I and III were solubilized. Two steps-sucrose density gradient centrifugation and anion-exchange chromatography on a POROS HQ 20 μm column-enabled selective purification of samples that retained their structure and functions. These two steps enabled complexes I, III, and V to be purified in two days with a high yield. Complexes I, III, and V were stabilized with n-decyl-β-D-maltoside. A total of 200 mg-300 mg of those complexes from one bovine heart (1.1 kg muscle) was purified with good reproducibility, and the complexes retained the same functions they possessed while in mitochondrial membranes.
Collapse
Affiliation(s)
- Satoru Shimada
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Koto 3-2-1, Kamighori, Ako, Hyogo, 678-1297, Japan
| | - Shintaro Maeda
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Koto 3-2-1, Kamighori, Ako, Hyogo, 678-1297, Japan
| | - Masahide Hikita
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Koto 3-2-1, Kamighori, Ako, Hyogo, 678-1297, Japan
| | - Kaoru Mieda-Higa
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Koto 3-2-1, Kamighori, Ako, Hyogo, 678-1297, Japan
| | - Shigefumi Uene
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Koto 3-2-1, Kamighori, Ako, Hyogo, 678-1297, Japan
| | - Yukiko Nariai
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Koto 3-2-1, Kamighori, Ako, Hyogo, 678-1297, Japan
| | - Kyoko Shinzawa-Itoh
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Koto 3-2-1, Kamighori, Ako, Hyogo, 678-1297, Japan.
| |
Collapse
|
19
|
Blaza JN, Vinothkumar KR, Hirst J. Structure of the Deactive State of Mammalian Respiratory Complex I. Structure 2018; 26:312-319.e3. [PMID: 29395787 PMCID: PMC5807054 DOI: 10.1016/j.str.2017.12.014] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 11/03/2017] [Accepted: 12/27/2017] [Indexed: 12/20/2022]
Abstract
Complex I (NADH:ubiquinone oxidoreductase) is central to energy metabolism in mammalian mitochondria. It couples NADH oxidation by ubiquinone to proton transport across the energy-conserving inner membrane, catalyzing respiration and driving ATP synthesis. In the absence of substrates, active complex I gradually enters a pronounced resting or deactive state. The active-deactive transition occurs during ischemia and is crucial for controlling how respiration recovers upon reperfusion. Here, we set a highly active preparation of Bos taurus complex I into the biochemically defined deactive state, and used single-particle electron cryomicroscopy to determine its structure to 4.1 Å resolution. We show that the deactive state arises when critical structural elements that form the ubiquinone-binding site become disordered, and we propose reactivation is induced when substrate binding to the NADH-reduced enzyme templates their reordering. Our structure both rationalizes biochemical data on the deactive state and offers new insights into its physiological and cellular roles. Preparation of mammalian complex I in the deactive state that forms during ischemia The structure of the deactive state determined using electron cryomicroscopy Improved particle densities and orientations obtained using PEGylated gold grids Localized unfolding around the quinone-binding site in the deactive state
Collapse
Affiliation(s)
- James N Blaza
- MRC Mitochondrial Biology Unit, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Kutti R Vinothkumar
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Judy Hirst
- MRC Mitochondrial Biology Unit, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK.
| |
Collapse
|
20
|
Letts JA, Sazanov LA. Clarifying the supercomplex: the higher-order organization of the mitochondrial electron transport chain. Nat Struct Mol Biol 2017; 24:800-808. [PMID: 28981073 DOI: 10.1038/nsmb.3460] [Citation(s) in RCA: 231] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 08/03/2017] [Indexed: 12/27/2022]
Abstract
The oxidative phosphorylation electron transport chain (OXPHOS-ETC) of the inner mitochondrial membrane is composed of five large protein complexes, named CI-CV. These complexes convert energy from the food we eat into ATP, a small molecule used to power a multitude of essential reactions throughout the cell. OXPHOS-ETC complexes are organized into supercomplexes (SCs) of defined stoichiometry: CI forms a supercomplex with CIII2 and CIV (SC I+III2+IV, known as the respirasome), as well as with CIII2 alone (SC I+III2). CIII2 forms a supercomplex with CIV (SC III2+IV) and CV forms dimers (CV2). Recent cryo-EM studies have revealed the structures of SC I+III2+IV and SC I+III2. Furthermore, recent work has shed light on the assembly and function of the SCs. Here we review and compare these recent studies and discuss how they have advanced our understanding of mitochondrial electron transport.
Collapse
Affiliation(s)
- James A Letts
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Leonid A Sazanov
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| |
Collapse
|
21
|
Abstract
The organization of metabolic multienzyme complexes has been hypothesized to benefit metabolic processes and provide a coordinated way for the cell to regulate metabolism. Historically, their existence has been supported by various in vitro techniques. However, it is only recently that the existence of metabolic complexes inside living cells has come to light to corroborate this long-standing hypothesis. Indeed, subcellular compartmentalization of metabolic enzymes appears to be widespread and highly regulated. On the other hand, it is still challenging to demonstrate the functional significance of these enzyme complexes in the context of the cellular milieu. In this review, we discuss the current understanding of metabolic enzyme complexes by primarily focusing on central carbon metabolism and closely associated metabolic pathways in a variety of organisms, as well as their regulation and functional contributions to cells.
Collapse
Affiliation(s)
- Danielle L Schmitt
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County (UMBC) , 1000 Hilltop Circle, Baltimore, Maryland 21250, United States
| | - Songon An
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County (UMBC) , 1000 Hilltop Circle, Baltimore, Maryland 21250, United States
| |
Collapse
|
22
|
Sousa JS, Mills DJ, Vonck J, Kühlbrandt W. Functional asymmetry and electron flow in the bovine respirasome. eLife 2016; 5. [PMID: 27830641 PMCID: PMC5117854 DOI: 10.7554/elife.21290] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 11/03/2016] [Indexed: 01/11/2023] Open
Abstract
Respirasomes are macromolecular assemblies of the respiratory chain complexes I, III and IV in the inner mitochondrial membrane. We determined the structure of supercomplex I1III2IV1 from bovine heart mitochondria by cryo-EM at 9 Å resolution. Most protein-protein contacts between complex I, III and IV in the membrane are mediated by supernumerary subunits. Of the two Rieske iron-sulfur cluster domains in the complex III dimer, one is resolved, indicating that this domain is immobile and unable to transfer electrons. The central position of the active complex III monomer between complex I and IV in the respirasome is optimal for accepting reduced quinone from complex I over a short diffusion distance of 11 nm, and delivering reduced cytochrome c to complex IV. The functional asymmetry of complex III provides strong evidence for directed electron flow from complex I to complex IV through the active complex III monomer in the mammalian supercomplex. DOI:http://dx.doi.org/10.7554/eLife.21290.001
Collapse
Affiliation(s)
- Joana S Sousa
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Deryck J Mills
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Janet Vonck
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Werner Kühlbrandt
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| |
Collapse
|
23
|
Fiedorczuk K, Letts JA, Degliesposti G, Kaszuba K, Skehel M, Sazanov LA. Atomic structure of the entire mammalian mitochondrial complex I. Nature 2016; 538:406-410. [PMID: 27595392 DOI: 10.1038/nature19794] [Citation(s) in RCA: 359] [Impact Index Per Article: 44.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 08/26/2016] [Indexed: 12/15/2022]
Abstract
Mitochondrial complex I (also known as NADH:ubiquinone oxidoreductase) contributes to cellular energy production by transferring electrons from NADH to ubiquinone coupled to proton translocation across the membrane. It is the largest protein assembly of the respiratory chain with a total mass of 970 kilodaltons. Here we present a nearly complete atomic structure of ovine (Ovis aries) mitochondrial complex I at 3.9 Å resolution, solved by cryo-electron microscopy with cross-linking and mass-spectrometry mapping experiments. All 14 conserved core subunits and 31 mitochondria-specific supernumerary subunits are resolved within the L-shaped molecule. The hydrophilic matrix arm comprises flavin mononucleotide and 8 iron-sulfur clusters involved in electron transfer, and the membrane arm contains 78 transmembrane helices, mostly contributed by antiporter-like subunits involved in proton translocation. Supernumerary subunits form an interlinked, stabilizing shell around the conserved core. Tightly bound lipids (including cardiolipins) further stabilize interactions between the hydrophobic subunits. Subunits with possible regulatory roles contain additional cofactors, NADPH and two phosphopantetheine molecules, which are shown to be involved in inter-subunit interactions. We observe two different conformations of the complex, which may be related to the conformationally driven coupling mechanism and to the active-deactive transition of the enzyme. Our structure provides insight into the mechanism, assembly, maturation and dysfunction of mitochondrial complex I, and allows detailed molecular analysis of disease-causing mutations.
Collapse
Affiliation(s)
- Karol Fiedorczuk
- Institute of Science and Technology Austria, Klosterneuburg 3400, Austria.,MRC Mitochondrial Biology Unit, Cambridge CB2 0XY, UK
| | - James A Letts
- Institute of Science and Technology Austria, Klosterneuburg 3400, Austria
| | | | - Karol Kaszuba
- Institute of Science and Technology Austria, Klosterneuburg 3400, Austria
| | - Mark Skehel
- MRC Laboratory of Molecular Biology, Cambridge CB2 OQH, UK
| | - Leonid A Sazanov
- Institute of Science and Technology Austria, Klosterneuburg 3400, Austria
| |
Collapse
|