1
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Sirohiwal A, Gamiz-Hernandez AP, Kaila VRI. Mechanistic Principles of Hydrogen Evolution in the Membrane-Bound Hydrogenase. J Am Chem Soc 2024; 146:18019-18031. [PMID: 38888987 PMCID: PMC11228991 DOI: 10.1021/jacs.4c04476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Revised: 05/22/2024] [Accepted: 05/23/2024] [Indexed: 06/20/2024]
Abstract
The membrane-bound hydrogenase (Mbh) from Pyrococcus furiosus is an archaeal member of the Complex I superfamily. It catalyzes the reduction of protons to H2 gas powered by a [NiFe] active site and transduces the free energy into proton pumping and Na+/H+ exchange across the membrane. Despite recent structural advances, the mechanistic principles of H2 catalysis and ion transport in Mbh remain elusive. Here, we probe how the redox chemistry drives the reduction of the proton to H2 and how the catalysis couples to conformational dynamics in the membrane domain of Mbh. By combining large-scale quantum chemical density functional theory (DFT) and correlated ab initio wave function methods with atomistic molecular dynamics simulations, we show that the proton transfer reactions required for the catalysis are gated by electric field effects that direct the protons by water-mediated reactions from Glu21L toward the [NiFe] site, or alternatively along the nearby His75L pathway that also becomes energetically feasible in certain reaction steps. These local proton-coupled electron transfer (PCET) reactions induce conformational changes around the active site that provide a key coupling element via conserved loop structures to the ion transport activity. We find that H2 forms in a heterolytic proton reduction step, with spin crossovers tuning the energetics along key reaction steps. On a general level, our work showcases the role of electric fields in enzyme catalysis and how these effects are employed by the [NiFe] active site of Mbh to drive PCET reactions and ion transport.
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Affiliation(s)
- Abhishek Sirohiwal
- Department of Biochemistry
and Biophysics, Stockholm University, Stockholm 10691, Sweden
| | - Ana P. Gamiz-Hernandez
- Department of Biochemistry
and Biophysics, Stockholm University, Stockholm 10691, Sweden
| | - Ville R. I. Kaila
- Department of Biochemistry
and Biophysics, Stockholm University, Stockholm 10691, Sweden
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2
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Riepl D, Gamiz-Hernandez AP, Kovalova T, Król SM, Mader SL, Sjöstrand D, Högbom M, Brzezinski P, Kaila VRI. Long-range charge transfer mechanism of the III 2IV 2 mycobacterial supercomplex. Nat Commun 2024; 15:5276. [PMID: 38902248 PMCID: PMC11189923 DOI: 10.1038/s41467-024-49628-9] [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: 11/16/2023] [Accepted: 06/12/2024] [Indexed: 06/22/2024] Open
Abstract
Aerobic life is powered by membrane-bound redox enzymes that shuttle electrons to oxygen and transfer protons across a biological membrane. Structural studies suggest that these energy-transducing enzymes operate as higher-order supercomplexes, but their functional role remains poorly understood and highly debated. Here we resolve the functional dynamics of the 0.7 MDa III2IV2 obligate supercomplex from Mycobacterium smegmatis, a close relative of M. tuberculosis, the causative agent of tuberculosis. By combining computational, biochemical, and high-resolution (2.3 Å) cryo-electron microscopy experiments, we show how the mycobacterial supercomplex catalyses long-range charge transport from its menaquinol oxidation site to the binuclear active site for oxygen reduction. Our data reveal proton and electron pathways responsible for the charge transfer reactions, mechanistic principles of the quinone catalysis, and how unique molecular adaptations, water molecules, and lipid interactions enable the proton-coupled electron transfer (PCET) reactions. Our combined findings provide a mechanistic blueprint of mycobacterial supercomplexes and a basis for developing drugs against pathogenic bacteria.
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Affiliation(s)
- Daniel Riepl
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Ana P Gamiz-Hernandez
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Terezia Kovalova
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Sylwia M Król
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Sophie L Mader
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Dan Sjöstrand
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Martin Högbom
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Peter Brzezinski
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Ville R I Kaila
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden.
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3
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Grba DN, Wright JJ, Yin Z, Fisher W, Hirst J. Molecular mechanism of the ischemia-induced regulatory switch in mammalian complex I. Science 2024; 384:1247-1253. [PMID: 38870289 DOI: 10.1126/science.ado2075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Accepted: 05/01/2024] [Indexed: 06/15/2024]
Abstract
Respiratory complex I is an efficient driver for oxidative phosphorylation in mammalian mitochondria, but its uncontrolled catalysis under challenging conditions leads to oxidative stress and cellular damage. Ischemic conditions switch complex I from rapid, reversible catalysis into a dormant state that protects upon reoxygenation, but the molecular basis for the switch is unknown. We combined precise biochemical definition of complex I catalysis with high-resolution cryo-electron microscopy structures in the phospholipid bilayer of coupled vesicles to reveal the mechanism of the transition into the dormant state, modulated by membrane interactions. By implementing a versatile membrane system to unite structure and function, attributing catalytic and regulatory properties to specific structural states, we define how a conformational switch in complex I controls its physiological roles.
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Affiliation(s)
| | | | | | | | - Judy Hirst
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
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4
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Djurabekova A, Lasham J, Zdorevskyi O, Zickermann V, Sharma V. Long-range electron proton coupling in respiratory complex I - insights from molecular simulations of the quinone chamber and antiporter-like subunits. Biochem J 2024; 481:499-514. [PMID: 38572757 DOI: 10.1042/bcj20240009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 03/11/2024] [Accepted: 03/14/2024] [Indexed: 04/05/2024]
Abstract
Respiratory complex I is a redox-driven proton pump. Several high-resolution structures of complex I have been determined providing important information about the putative proton transfer paths and conformational transitions that may occur during catalysis. However, how redox energy is coupled to the pumping of protons remains unclear. In this article, we review biochemical, structural and molecular simulation data on complex I and discuss several coupling models, including the key unresolved mechanistic questions. Focusing both on the quinone-reductase domain as well as the proton-pumping membrane-bound domain of complex I, we discuss a molecular mechanism of proton pumping that satisfies most experimental and theoretical constraints. We suggest that protonation reactions play an important role not only in catalysis, but also in the physiologically-relevant active/deactive transition of complex I.
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Affiliation(s)
| | - Jonathan Lasham
- Department of Physics, University of Helsinki, Helsinki, Finland
| | | | - Volker Zickermann
- Institute of Biochemistry II, University Hospital, Goethe University, Frankfurt am Main, Germany
- Centre for Biomolecular Magnetic Resonance, Institute for Biophysical Chemistry, Goethe University, Frankfurt am Main, Germany
| | - Vivek Sharma
- Department of Physics, University of Helsinki, Helsinki, Finland
- HiLIFE Institute of Biotechnology, University of Helsinki, Helsinki, Finland
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5
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Kim H, Saura P, Pöverlein MC, Gamiz-Hernandez AP, Kaila VRI. Quinone Catalysis Modulates Proton Transfer Reactions in the Membrane Domain of Respiratory Complex I. J Am Chem Soc 2023; 145:17075-17086. [PMID: 37490414 PMCID: PMC10416309 DOI: 10.1021/jacs.3c03086] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Indexed: 07/27/2023]
Abstract
Complex I is a redox-driven proton pump that drives electron transport chains and powers oxidative phosphorylation across all domains of life. Yet, despite recently resolved structures from multiple organisms, it still remains unclear how the redox reactions in Complex I trigger proton pumping up to 200 Å away from the active site. Here, we show that the proton-coupled electron transfer reactions during quinone reduction drive long-range conformational changes of conserved loops and trans-membrane (TM) helices in the membrane domain of Complex I from Yarrowia lipolytica. We find that the conformational switching triggers a π → α transition in a TM helix (TM3ND6) and establishes a proton pathway between the quinone chamber and the antiporter-like subunits, responsible for proton pumping. Our large-scale (>20 μs) atomistic molecular dynamics (MD) simulations in combination with quantum/classical (QM/MM) free energy calculations show that the helix transition controls the barrier for proton transfer reactions by wetting transitions and electrostatic effects. The conformational switching is enabled by re-arrangements of ion pairs that propagate from the quinone binding site to the membrane domain via an extended network of conserved residues. We find that these redox-driven changes create a conserved coupling network within the Complex I superfamily, with point mutations leading to drastic activity changes and mitochondrial disorders. On a general level, our findings illustrate how catalysis controls large-scale protein conformational changes and enables ion transport across biological membranes.
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Affiliation(s)
- Hyunho Kim
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm 10691, Sweden
| | - Patricia Saura
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm 10691, Sweden
| | | | - Ana P. Gamiz-Hernandez
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm 10691, Sweden
| | - Ville R. I. Kaila
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm 10691, Sweden
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6
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Grba DN, Chung I, Bridges HR, Agip ANA, Hirst J. Investigation of hydrated channels and proton pathways in a high-resolution cryo-EM structure of mammalian complex I. SCIENCE ADVANCES 2023; 9:eadi1359. [PMID: 37531432 PMCID: PMC10396290 DOI: 10.1126/sciadv.adi1359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 07/03/2023] [Indexed: 08/04/2023]
Abstract
Respiratory complex I, a key enzyme in mammalian metabolism, captures the energy released by reduction of ubiquinone by NADH to drive protons across the inner mitochondrial membrane, generating the proton-motive force for ATP synthesis. Despite remarkable advances in structural knowledge of this complicated membrane-bound enzyme, its mechanism of catalysis remains controversial. In particular, how ubiquinone reduction is coupled to proton pumping and the pathways and mechanisms of proton translocation are contested. We present a 2.4-Å resolution cryo-EM structure of complex I from mouse heart mitochondria in the closed, active (ready-to-go) resting state, with 2945 water molecules modeled. By analyzing the networks of charged and polar residues and water molecules present, we evaluate candidate pathways for proton transfer through the enzyme, for the chemical protons for ubiquinone reduction, and for the protons transported across the membrane. Last, we compare our data to the predictions of extant mechanistic models, and identify key questions to answer in future work to test them.
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7
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Ikunishi R, Otani R, Masuya T, Shinzawa-Itoh K, Shiba T, Murai M, Miyoshi H. Respiratory complex I in mitochondrial membrane catalyzes oversized ubiquinones. J Biol Chem 2023; 299:105001. [PMID: 37394006 PMCID: PMC10416054 DOI: 10.1016/j.jbc.2023.105001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 06/20/2023] [Accepted: 06/23/2023] [Indexed: 07/04/2023] Open
Abstract
NADH-ubiquinone (UQ) oxidoreductase (complex I) couples electron transfer from NADH to UQ with proton translocation in its membrane part. The UQ reduction step is key to triggering proton translocation. Structural studies have identified a long, narrow, tunnel-like cavity within complex I, through which UQ may access a deep reaction site. To elucidate the physiological relevance of this UQ-accessing tunnel, we previously investigated whether a series of oversized UQs (OS-UQs), whose tail moiety is too large to enter and transit the narrow tunnel, can be catalytically reduced by complex I using the native enzyme in bovine heart submitochondrial particles (SMPs) and the isolated enzyme reconstituted into liposomes. Nevertheless, the physiological relevance remained unclear because some amphiphilic OS-UQs were reduced in SMPs but not in proteoliposomes, and investigation of extremely hydrophobic OS-UQs was not possible in SMPs. To uniformly assess the electron transfer activities of all OS-UQs with the native complex I, here we present a new assay system using SMPs, which were fused with liposomes incorporating OS-UQ and supplemented with a parasitic quinol oxidase to recycle reduced OS-UQ. In this system, all OS-UQs tested were reduced by the native enzyme, and the reduction was coupled with proton translocation. This finding does not support the canonical tunnel model. We propose that the UQ reaction cavity is flexibly open in the native enzyme to allow OS-UQs to access the reaction site, but their access is obstructed in the isolated enzyme as the cavity is altered by detergent-solubilizing from the mitochondrial membrane.
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Affiliation(s)
- Ryo Ikunishi
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Ryohei Otani
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Takahiro Masuya
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Kyoko Shinzawa-Itoh
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Hyogo, Japan
| | - Tomoo Shiba
- Department of Applied Biology, Graduate School of Science and Technology, Kyoto Institute of Technology, Kyoto, Japan
| | - Masatoshi Murai
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Hideto Miyoshi
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan.
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8
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Wikström M, Djurabekova A, Sharma V. On the role of ubiquinone in the proton translocation mechanism of respiratory complex I. FEBS Lett 2023; 597:224-236. [PMID: 36180980 DOI: 10.1002/1873-3468.14506] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/23/2022] [Accepted: 09/23/2022] [Indexed: 01/26/2023]
Abstract
Complex I converts oxidoreduction energy into a proton electrochemical gradient across the inner mitochondrial or bacterial cell membrane. This gradient is the primary source of energy for aerobic synthesis of ATP. Oxidation of reduced nicotinamide adenine dinucleotide (NADH) by ubiquinone (Q) yields NAD+ and ubiquinol (QH2 ), which is tightly coupled to translocation of four protons from the negatively to the positively charged side of the membrane. Electrons from NADH oxidation reach the iron-sulfur centre N2 positioned near the bottom of a tunnel that extends circa 30 Å from the membrane domain into the hydrophilic domain of the complex. The tunnel is occupied by ubiquinone, which can take a distal position near the N2 centre or proximal positions closer to the membrane. Here, we review important structural, kinetic and thermodynamic properties of ubiquinone that define its role in complex I function. We suggest that this function exceeds that of a mere substrate or electron acceptor and propose that ubiquinone may be the redox element of complex I coupling electron transfer to proton translocation.
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Affiliation(s)
- Mårten Wikström
- HiLIFE Institute of Biotechnology, University of Helsinki, Finland
| | | | - Vivek Sharma
- HiLIFE Institute of Biotechnology, University of Helsinki, Finland.,Department of Physics, University of Helsinki, Finland
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9
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Ameixa J, Arthur-Baidoo E, Pereira-da-Silva J, Ončák M, Ruivo J, Varella MDN, Ferreira da Silva F, Denifl S. Parent anion radical formation in coenzyme Q 0: Breaking ubiquinone family rules. Comput Struct Biotechnol J 2022; 21:346-353. [PMID: 36582437 PMCID: PMC9792397 DOI: 10.1016/j.csbj.2022.12.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 12/06/2022] [Accepted: 12/06/2022] [Indexed: 12/13/2022] Open
Abstract
We report electron attachment (EA) measurements for the parent anion radical formation from coenzyme Q0 (CoQ0) at low electron energies (<2 eV) along with quantum chemical calculations. CoQ0 may be considered a prototype for the electron withdrawing properties of the larger CoQ n molecules, in particular ubiquinone (CoQ10), an electron carrier in aerobic cell respiration. Herein, we show that the mechanisms for the parent anion radical formation of CoQ0 and CoQ n (n = 1,2,4) are remarkably distinct. Reported EA data for CoQ1, CoQ2, CoQ4 and para-benzoquinone indicated stabilization of the parent anion radicals around 1.2-1.4 eV. In contrast, we observe for the yield of the parent anion radical of CoQ0 a sharp peak at ∼ 0 eV, a shoulder at 0.07 eV and a peak around 0.49 eV. Although the mechanisms for the latter feature remain unclear, our calculations suggest that a dipole bound state (DBS) would account for the lower energy signals. Additionally, the isoprenoid side chains in CoQ n (n = 1,2,4) molecules seem to influence the DBS formation for these compounds. In contrast, the side chains enhance the parent anion radical stabilization around 1.4 eV. The absence of parent anion radical formation around 1.4 eV for CoQ0 can be attributed to the short auto-ionization lifetimes. The present results shed light on the underappreciated role played by the side chains in the stabilization of the parent anion radical. The isoprenoid tails should be viewed as co-responsible for the electron-accepting properties of ubiquinone, not mere spectators of electron transfer reactions.
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Affiliation(s)
- J. Ameixa
- Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria,CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal,Center for Molecular Biosciences (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - E. Arthur-Baidoo
- Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria,Center for Molecular Biosciences (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - J. Pereira-da-Silva
- CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
| | - M. Ončák
- Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - J.C. Ruivo
- Institute of Physics, University of São Paulo, Rua do Matão 1731, 05508-090 São Paulo, Brazil
| | - M.T. do N. Varella
- Institute of Physics, University of São Paulo, Rua do Matão 1731, 05508-090 São Paulo, Brazil,Corresponding authors at: Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria (S. Denifl).
| | - F. Ferreira da Silva
- CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal,Corresponding authors at: Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria (S. Denifl).
| | - S. Denifl
- Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria,Center for Molecular Biosciences (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria,Corresponding authors at: Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria (S. Denifl).
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10
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Binding of Natural Inhibitors to Respiratory Complex I. Pharmaceuticals (Basel) 2022; 15:ph15091088. [PMID: 36145309 PMCID: PMC9503403 DOI: 10.3390/ph15091088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/23/2022] [Accepted: 08/24/2022] [Indexed: 11/26/2022] Open
Abstract
NADH:ubiquinone oxidoreductase (respiratory complex I) is a redox-driven proton pump with a central role in mitochondrial oxidative phosphorylation. The ubiquinone reduction site of complex I is located in the matrix arm of this large protein complex and connected to the membrane via a tunnel. A variety of chemically diverse compounds are known to inhibit ubiquinone reduction by complex I. Rotenone, piericidin A, and annonaceous acetogenins are representatives of complex I inhibitors from biological sources. The structure of complex I is determined at high resolution, and inhibitor binding sites are described in detail. In this review, we summarize the state of knowledge of how natural inhibitors bind in the Q reduction site and the Q access pathway and how their inhibitory mechanisms compare with that of a synthetic anti-cancer agent.
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11
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Uno S, Masuya T, Zdorevskyi O, Ikunishi R, Shinzawa-Itoh K, Lasham J, Sharma V, Murai M, Miyoshi H. Diverse reaction behaviors of artificial ubiquinones in mitochondrial respiratory complex I. J Biol Chem 2022; 298:102075. [PMID: 35643318 PMCID: PMC9243180 DOI: 10.1016/j.jbc.2022.102075] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 05/23/2022] [Accepted: 05/23/2022] [Indexed: 11/24/2022] Open
Abstract
The ubiquinone (UQ) reduction step catalyzed by NADH-UQ oxidoreductase (mitochondrial respiratory complex I) is key to triggering proton translocation across the inner mitochondrial membrane. Structural studies have identified a long, narrow, UQ-accessing tunnel within the enzyme. We previously demonstrated that synthetic oversized UQs, which are unlikely to transit this narrow tunnel, are catalytically reduced by native complex I embedded in submitochondrial particles but not by the isolated enzyme. To explain this contradiction, we hypothesized that access of oversized UQs to the reaction site is obstructed in the isolated enzyme because their access route is altered following detergent solubilization from the inner mitochondrial membrane. In the present study, we investigated this using two pairs of photoreactive UQs (pUQm-1/pUQp-1 and pUQm-2/pUQp-2), with each pair having the same chemical properties except for a ∼1.0 Å difference in side-chain widths. Despite this subtle difference, reduction of the wider pUQs by the isolated complex was significantly slower than of the narrower pUQs, but both were similarly reduced by the native enzyme. In addition, photoaffinity-labeling experiments using the four [125I]pUQs demonstrated that their side chains predominantly label the ND1 subunit with both enzymes but at different regions around the tunnel. Finally, we show that the suppressive effects of different types of inhibitors on the labeling significantly changed depending on [125I]pUQs used, indicating that [125I]pUQs and these inhibitors do not necessarily share a common binding cavity. Altogether, we conclude that the reaction behaviors of pUQs cannot be simply explained by the canonical UQ tunnel model.
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Affiliation(s)
- Shinpei Uno
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Takahiro Masuya
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | | | - Ryo Ikunishi
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Kyoko Shinzawa-Itoh
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Hyogo, Japan
| | - Jonathan Lasham
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Vivek Sharma
- Department of Physics, University of Helsinki, Helsinki, Finland; Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Masatoshi Murai
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Hideto Miyoshi
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan.
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12
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Cryo-EM structures define ubiquinone-10 binding to mitochondrial complex I and conformational transitions accompanying Q-site occupancy. Nat Commun 2022; 13:2758. [PMID: 35589726 PMCID: PMC9120487 DOI: 10.1038/s41467-022-30506-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 05/04/2022] [Indexed: 02/03/2023] Open
Abstract
Mitochondrial complex I is a central metabolic enzyme that uses the reducing potential of NADH to reduce ubiquinone-10 (Q10) and drive four protons across the inner mitochondrial membrane, powering oxidative phosphorylation. Although many complex I structures are now available, the mechanisms of Q10 reduction and energy transduction remain controversial. Here, we reconstitute mammalian complex I into phospholipid nanodiscs with exogenous Q10. Using cryo-EM, we reveal a Q10 molecule occupying the full length of the Q-binding site in the 'active' (ready-to-go) resting state together with a matching substrate-free structure, and apply molecular dynamics simulations to propose how the charge states of key residues influence the Q10 binding pose. By comparing ligand-bound and ligand-free forms of the 'deactive' resting state (that require reactivating to catalyse), we begin to define how substrate binding restructures the deactive Q-binding site, providing insights into its physiological and mechanistic relevance.
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13
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Grba DN, Blaza JN, Bridges HR, Agip ANA, Yin Z, Murai M, Miyoshi H, Hirst J. Cryo-electron microscopy reveals how acetogenins inhibit mitochondrial respiratory complex I. J Biol Chem 2022; 298:101602. [PMID: 35063503 PMCID: PMC8861642 DOI: 10.1016/j.jbc.2022.101602] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 01/10/2022] [Accepted: 01/11/2022] [Indexed: 12/22/2022] Open
Abstract
Mitochondrial complex I (NADH:ubiquinone oxidoreductase), a crucial enzyme in energy metabolism, captures the redox potential energy from NADH oxidation/ubiquinone reduction to create the proton motive force used to drive ATP synthesis in oxidative phosphorylation. High-resolution single-particle electron cryo-EM analyses have provided detailed structural knowledge of the catalytic machinery of complex I, but not of the molecular principles of its energy transduction mechanism. Although ubiquinone is considered to bind in a long channel at the interface of the membrane-embedded and hydrophilic domains, with channel residues likely involved in coupling substrate reduction to proton translocation, no structures with the channel fully occupied have yet been described. Here, we report the structure (determined by cryo-EM) of mouse complex I with a tight-binding natural product acetogenin inhibitor, which resembles the native substrate, bound along the full length of the expected ubiquinone-binding channel. Our structure reveals the mode of acetogenin binding and the molecular basis for structure-activity relationships within the acetogenin family. It also shows that acetogenins are such potent inhibitors because they are highly hydrophobic molecules that contain two specific hydrophilic moieties spaced to lock into two hydrophilic regions of the otherwise hydrophobic channel. The central hydrophilic section of the channel does not favor binding of the isoprenoid chain when the native substrate is fully bound but stabilizes the ubiquinone/ubiquinol headgroup as it transits to/from the active site. Therefore, the amphipathic nature of the channel supports both tight binding of the amphipathic inhibitor and rapid exchange of the ubiquinone/ubiquinol substrate and product.
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Affiliation(s)
- Daniel N Grba
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - James N Blaza
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Hannah R Bridges
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Ahmed-Noor A Agip
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Zhan Yin
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Masatoshi Murai
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Hideto Miyoshi
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Judy Hirst
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK.
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14
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Kaila VRI. Resolving Chemical Dynamics in Biological Energy Conversion: Long-Range Proton-Coupled Electron Transfer in Respiratory Complex I. Acc Chem Res 2021; 54:4462-4473. [PMID: 34894649 PMCID: PMC8697550 DOI: 10.1021/acs.accounts.1c00524] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
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Biological energy conversion is catalyzed by membrane-bound proteins
that transduce chemical or light energy into energy forms that power
endergonic processes in the cell. At a molecular level, these catalytic
processes involve elementary electron-, proton-, charge-, and energy-transfer
reactions that take place in the intricate molecular machineries of
cell respiration and photosynthesis. Recent developments in structural
biology, particularly cryo-electron microscopy (cryoEM), have resolved
the molecular architecture of several energy transducing proteins,
but detailed mechanistic principles of their charge transfer reactions
still remain poorly understood and a major challenge for modern biochemical
research. To this end, multiscale molecular simulations provide a
powerful approach to probe mechanistic principles on a broad range
of time scales (femtoseconds to milliseconds) and spatial resolutions
(101–106 atoms), although technical challenges
also require balancing between the computational accuracy, cost, and
approximations introduced within the model. Here we discuss how the
combination of atomistic (aMD) and hybrid quantum/classical molecular
dynamics (QM/MM MD) simulations with free energy (FE) sampling methods
can be used to probe mechanistic principles of enzymes responsible
for biological energy conversion. We present mechanistic explorations
of long-range proton-coupled electron transfer (PCET) dynamics in
the highly intricate respiratory chain enzyme Complex I, which functions
as a redox-driven proton pump in bacterial and mitochondrial respiratory
chains by catalyzing a 300 Å fully reversible PCET process. This
process is initiated by a hydride (H–) transfer
between NADH and FMN, followed by long-range (>100 Å) electron
transfer along a wire of 8 FeS centers leading to a quinone biding
site. The reduction of the quinone to quinol initiates dissociation
of the latter to a second membrane-bound binding site, and triggers
proton pumping across the membrane domain of complex I, in subunits
up to 200 Å away from the active site. Our simulations across
different size and time scales suggest that transient charge transfer
reactions lead to changes in the internal hydration state of key regions,
local electric fields, and the conformation of conserved ion pairs,
which in turn modulate the dynamics of functional steps along the
reaction cycle. Similar functional principles, which operate on much
shorter length scales, are also found in some unrelated proteins,
suggesting that enzymes may employ conserved principles in the catalysis
of biological energy transduction processes.
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Affiliation(s)
- Ville R. I. Kaila
- Department of Biochemistry and Biophysics, Stockholm University, 10691 Stockholm, Sweden
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15
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Poor Person's pH Simulation of Membrane Proteins. Methods Mol Biol 2021. [PMID: 34302678 DOI: 10.1007/978-1-0716-1468-6_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/01/2023]
Abstract
pH conditions are central to the functioning of all biomolecules. However, implications of pH changes are nontrivial on a molecular scale. Though a rigorous microscopic definition of pH exists, its implementation in classical molecular dynamics (MD) simulations is cumbersome, and more so in large integral membrane systems. In this chapter, an integrative pipeline is described that combines Multi-Conformation Continuum Electrostatics (MCCE) computations with MD simulations to capture the effect of transient protonation states on the coupled conformational changes in transmembrane proteins. The core methodologies are explained, and all the software required to set up this pipeline are outlined with their key parameters. All associated analyses of structure and function are provided using two case studies, namely those of bioenergetic complexes: NADH dehydrogenase (complex I) and Vo domain of V-type ATPase. The hybrid MCCE-MD pipeline has allowed the discovery of hydrogen bond networks, ligand binding pathways, and disease-causing mutations.
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16
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Abstract
The electron transport chain of mitochondria is initiated by the respiratory complex I that converts chemical energy into a proton motive force to power synthesis of adenosine triphosphate. On a chemical level, complex I catalyzes elementary electron and proton transfer processes that couple across large molecular distances of >300 Å. However, under low oxygen concentrations, the respiratory chain operates in reverse mode and produces harmful reactive oxygen species. To avoid cell damage, the mitochondrial complex I transitions into a deactive state that inhibits turnover by molecular principles that remain elusive. By combining large-scale molecular simulations with cryo-electron microscopy data, we show here that complex I deactivation blocks the communication between proton pumping and redox modules by conformational and hydration changes. Cellular respiration is powered by membrane-bound redox enzymes that convert chemical energy into an electrochemical proton gradient and drive the energy metabolism. By combining large-scale classical and quantum mechanical simulations with cryo-electron microscopy data, we resolve here molecular details of conformational changes linked to proton pumping in the mammalian complex I. Our data suggest that complex I deactivation blocks water-mediated proton transfer between a membrane-bound quinone site and proton-pumping modules, decoupling the energy-transduction machinery. We identify a putative gating region at the interface between membrane domain subunits ND1 and ND3/ND4L/ND6 that modulates the proton transfer by conformational changes in transmembrane helices and bulky residues. The region is perturbed by mutations linked to human mitochondrial disorders and is suggested to also undergo conformational changes during catalysis of simpler complex I variants that lack the “active”-to-“deactive” transition. Our findings suggest that conformational changes in transmembrane helices modulate the proton transfer dynamics by wetting/dewetting transitions and provide important functional insight into the mammalian respiratory complex I.
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17
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Biochemical consequences of two clinically relevant ND-gene mutations in Escherichia coli respiratory complex I. Sci Rep 2021; 11:12641. [PMID: 34135385 PMCID: PMC8209014 DOI: 10.1038/s41598-021-91631-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 05/28/2021] [Indexed: 11/28/2022] Open
Abstract
NADH:ubiquinone oxidoreductase (respiratory complex I) plays a major role in energy metabolism by coupling electron transfer from NADH to quinone with proton translocation across the membrane. Complex I deficiencies were found to be the most common source of human mitochondrial dysfunction that manifest in a wide variety of neurodegenerative diseases. Seven subunits of human complex I are encoded by mitochondrial DNA (mtDNA) that carry an unexpectedly large number of mutations discovered in mitochondria from patients’ tissues. However, whether or how these genetic aberrations affect complex I at a molecular level is unknown. Here, we used Escherichia coli as a model system to biochemically characterize two mutations that were found in mtDNA of patients. The V253AMT-ND5 mutation completely disturbed the assembly of complex I, while the mutation D199GMT-ND1 led to the assembly of a stable complex capable to catalyze redox-driven proton translocation. However, the latter mutation perturbs quinone reduction leading to a diminished activity. D199MT-ND1 is part of a cluster of charged amino acid residues that are suggested to be important for efficient coupling of quinone reduction and proton translocation. A mechanism considering the role of D199MT-ND1 for energy conservation in complex I is discussed.
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18
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Kaur D, Khaniya U, Zhang Y, Gunner MR. Protein Motifs for Proton Transfers That Build the Transmembrane Proton Gradient. Front Chem 2021; 9:660954. [PMID: 34211960 PMCID: PMC8239185 DOI: 10.3389/fchem.2021.660954] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 05/31/2021] [Indexed: 11/13/2022] Open
Abstract
Biological membranes are barriers to polar molecules, so membrane embedded proteins control the transfers between cellular compartments. Protein controlled transport moves substrates and activates cellular signaling cascades. In addition, the electrochemical gradient across mitochondrial, bacterial and chloroplast membranes, is a key source of stored cellular energy. This is generated by electron, proton and ion transfers through proteins. The gradient is used to fuel ATP synthesis and to drive active transport. Here the mechanisms by which protons move into the buried active sites of Photosystem II (PSII), bacterial RCs (bRCs) and through the proton pumps, Bacteriorhodopsin (bR), Complex I and Cytochrome c oxidase (CcO), are reviewed. These proteins all use water filled proton transfer paths. The proton pumps, that move protons uphill from low to high concentration compartments, also utilize Proton Loading Sites (PLS), that transiently load and unload protons and gates, which block backflow of protons. PLS and gates should be synchronized so PLS proton affinity is high when the gate opens to the side with few protons and low when the path is open to the high concentration side. Proton transfer paths in the proteins we describe have different design features. Linear paths are seen with a unique entry and exit and a relatively straight path between them. Alternatively, paths can be complex with a tangle of possible routes. Likewise, PLS can be a single residue that changes protonation state or a cluster of residues with multiple charge and tautomer states.
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Affiliation(s)
- Divya Kaur
- Department of Chemistry, The Graduate Center, City University of New York, New York, NY, United States.,Department of Physics, City College of New York, New York, NY, United States
| | - Umesh Khaniya
- Department of Physics, City College of New York, New York, NY, United States.,Department of Physics, The Graduate Center, City University of New York, New York, NY, United States
| | - Yingying Zhang
- Department of Physics, City College of New York, New York, NY, United States.,Department of Physics, The Graduate Center, City University of New York, New York, NY, United States
| | - M R Gunner
- Department of Chemistry, The Graduate Center, City University of New York, New York, NY, United States.,Department of Physics, City College of New York, New York, NY, United States.,Department of Physics, The Graduate Center, City University of New York, New York, NY, United States
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19
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Nuber F, Mérono L, Oppermann S, Schimpf J, Wohlwend D, Friedrich T. A Quinol Anion as Catalytic Intermediate Coupling Proton Translocation With Electron Transfer in E. coli Respiratory Complex I. Front Chem 2021; 9:672969. [PMID: 34026733 PMCID: PMC8138167 DOI: 10.3389/fchem.2021.672969] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 04/09/2021] [Indexed: 11/18/2022] Open
Abstract
Energy-converting NADH:ubiquinone oxidoreductase, respiratory complex I, plays a major role in cellular energy metabolism. It couples NADH oxidation and quinone reduction with the translocation of protons across the membrane, thus contributing to the protonmotive force. Complex I has an overall L-shaped structure with a peripheral arm catalyzing electron transfer and a membrane arm engaged in proton translocation. Although both reactions are arranged spatially separated, they are tightly coupled by a mechanism that is not fully understood. Using redox-difference UV-vis spectroscopy, an unknown redox component was identified in Escherichia coli complex I as reported earlier. A comparison of its spectrum with those obtained for different quinone species indicates features of a quinol anion. The re-oxidation kinetics of the quinol anion intermediate is significantly slower in the D213GH variant that was previously shown to operate with disturbed quinone chemistry. Addition of the quinone-site inhibitor piericidin A led to strongly decreased absorption peaks in the difference spectrum. A hypothesis for a mechanism of proton-coupled electron transfer with the quinol anion as catalytically important intermediate in complex I is discussed.
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Affiliation(s)
- Franziska Nuber
- Institut für Biochemie, Albert-Ludwigs-Universität, Freiburg, Germany
| | - Luca Mérono
- Institut für Biochemie, Albert-Ludwigs-Universität, Freiburg, Germany
| | - Sabrina Oppermann
- Institut für Biochemie, Albert-Ludwigs-Universität, Freiburg, Germany
| | - Johannes Schimpf
- Institut für Biochemie, Albert-Ludwigs-Universität, Freiburg, Germany
| | - Daniel Wohlwend
- Institut für Biochemie, Albert-Ludwigs-Universität, Freiburg, Germany
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20
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Galemou Yoga E, Schiller J, Zickermann V. Ubiquinone Binding and Reduction by Complex I-Open Questions and Mechanistic Implications. Front Chem 2021; 9:672851. [PMID: 33996767 PMCID: PMC8119997 DOI: 10.3389/fchem.2021.672851] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 04/06/2021] [Indexed: 11/13/2022] Open
Abstract
NADH: ubiquinone oxidoreductase (complex I) is the first enzyme complex of the respiratory chain. Complex I is a redox-driven proton pump that contributes to the proton motive force that drives ATP synthase. The structure of complex I has been analyzed by x-ray crystallography and electron cryo-microscopy and is now well-described. The ubiquinone (Q) reduction site of complex I is buried in the peripheral arm and a tunnel-like structure is thought to provide access for the hydrophobic substrate from the membrane. Several intermediate binding positions for Q in the tunnel were identified in molecular simulations. Structural data showed the binding of native Q molecules and short chain analogs and inhibitors in the access pathway and in the Q reduction site, respectively. We here review the current knowledge on the interaction of complex I with Q and discuss recent hypothetical models for the coupling mechanism.
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Affiliation(s)
- Etienne Galemou Yoga
- Institute of Biochemistry II, University Hospital, Goethe University, Frankfurt, Germany.,Centre for Biomolecular Magnetic Resonance, Institute for Biophysical Chemistry, Goethe University, Frankfurt, Germany
| | - Jonathan Schiller
- Institute of Biochemistry II, University Hospital, Goethe University, Frankfurt, Germany.,Centre for Biomolecular Magnetic Resonance, Institute for Biophysical Chemistry, Goethe University, Frankfurt, Germany
| | - Volker Zickermann
- Institute of Biochemistry II, University Hospital, Goethe University, Frankfurt, Germany.,Centre for Biomolecular Magnetic Resonance, Institute for Biophysical Chemistry, Goethe University, Frankfurt, Germany
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21
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Masuya T, Uno S, Murai M, Miyoshi H. Pinpoint Dual Chemical Cross-Linking Explores the Structural Dynamics of the Ubiquinone Reaction Site in Mitochondrial Complex I. Biochemistry 2021; 60:813-824. [PMID: 33650850 DOI: 10.1021/acs.biochem.0c00991] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The ubiquinone reduction step in NADH-ubiquinone oxidoreductase (complex I) is the key to triggering proton translocation in its membrane part. Although the existence of a long and narrow quinone-access channel has been identified, it remains debatable whether the channel model can account for binding of various ligands (ubiquinones and inhibitors) to the enzyme. We previously proposed that the matrix-side interfacial region of the 49 kDa, ND1, PSST, and 39 kDa subunits, which is covered by a loop connecting transmembrane helices (TMHs) 1 and 2 of ND3, may be the area for entry of some bulky ligands into the quinone reaction cavity. However, this proposition lacks direct evidence that the cavity is accessible from the putative matrix-side region, which allows ligands to pass. To address this, we examined whether Cys39 of ND3 and Asp160 of 49 kDa can be specifically cross-linked by bifunctional cross-linkers (tetrazine-maleimide hybrid, named TMBC). On the basis of the structural models of complex I, such dual cross-linking is unexpected because ND3 Cys39 and 49 kDa Asp160 are located on the TMH1-2 loop and deep inside the channel, respectively, and hence, they are physically separated by peptide chains forming the channel wall. However, three TMBCs with different spacer lengths did cross-link the two residues, resulting in the formation of new cross-linked ND3/49 kDa subunits. Chemical modification of either ND3 Cys39 or 49 kDa Asp160 blocked the dual cross-linking, ensuring the specificity of the cross-linking. Altogether, this study provides direct evidence that the quinone reaction cavity is indeed accessible from the proposed matrix-side region covered by the ND3 TMH1-2 loop.
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Affiliation(s)
- Takahiro Masuya
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Shinpei Uno
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Masatoshi Murai
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Hideto Miyoshi
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
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22
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Di Luca A, Kaila VRI. Molecular strain in the active/deactive-transition modulates domain coupling in respiratory complex I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148382. [PMID: 33513365 DOI: 10.1016/j.bbabio.2021.148382] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 09/19/2020] [Revised: 01/08/2021] [Accepted: 01/21/2021] [Indexed: 12/14/2022]
Abstract
Complex I functions as a primary redox-driven proton pump in aerobic respiratory chains, establishing a proton motive force that powers ATP synthesis and active transport. Recent cryo-electron microscopy (cryo-EM) experiments have resolved the mammalian complex I in the biomedically relevant active (A) and deactive (D) states (Zhu et al., 2016; Fiedorczuk et al., 2016; Agip et al., 2018 [1-3]) that could regulate enzyme turnover, but it still remains unclear how the conformational state and activity are linked. We show here how global motion along the A/D transition accumulates molecular strain at specific coupling regions important for both redox chemistry and proton pumping. Our data suggest that the A/D motion modulates force propagation pathways between the substrate-binding site and the proton pumping machinery that could alter electrostatic and conformational coupling across large distances. Our findings provide a molecular basis to understand how global protein dynamics can modulate the biological activity of large molecular complexes.
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Affiliation(s)
- Andrea Di Luca
- Department of Biochemistry and Biophysics, Stockholm University, 10691 Stockholm, Sweden
| | - Ville R I Kaila
- Department of Biochemistry and Biophysics, Stockholm University, 10691 Stockholm, Sweden.
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23
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Röpke M, Saura P, Riepl D, Pöverlein MC, Kaila VRI. Functional Water Wires Catalyze Long-Range Proton Pumping in the Mammalian Respiratory Complex I. J Am Chem Soc 2020; 142:21758-21766. [PMID: 33325238 PMCID: PMC7785131 DOI: 10.1021/jacs.0c09209] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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The respiratory complex I is a gigantic
(1 MDa) redox-driven proton
pump that reduces the ubiquinone pool and generates proton motive
force to power ATP synthesis in mitochondria. Despite resolved molecular
structures and biochemical characterization of the enzyme from multiple
organisms, its long-range (∼300 Å) proton-coupled electron
transfer (PCET) mechanism remains unsolved. We employ here microsecond
molecular dynamics simulations to probe the dynamics of the mammalian
complex I in combination with hybrid quantum/classical (QM/MM) free
energy calculations to explore how proton pumping reactions are triggered
within its 200 Å wide membrane domain. Our simulations predict
extensive hydration dynamics of the antiporter-like subunits in complex
I that enable lateral proton transfer reactions on a microsecond time
scale. We further show how the coupling between conserved ion pairs
and charged residues modulate the proton transfer dynamics, and how
transmembrane helices and gating residues control the hydration process.
Our findings suggest that the mammalian complex I pumps protons by
tightly linked conformational and electrostatic coupling principles.
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Affiliation(s)
- Michael Röpke
- Center for Integrated Protein Science Munich at the Department of Chemistry, Technical University of Munich, Lichtenbergstrasse 4, D85748 Garching, Germany
| | - Patricia Saura
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Daniel Riepl
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Maximilian C Pöverlein
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Ville R I Kaila
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.,Center for Integrated Protein Science Munich at the Department of Chemistry, Technical University of Munich, Lichtenbergstrasse 4, D85748 Garching, Germany
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24
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Abstract
Respiratory complex I (NADH:ubiquinone oxidoreductase) captures the free energy from oxidising NADH and reducing ubiquinone to drive protons across the mitochondrial inner membrane and power oxidative phosphorylation. Recent cryo-EM analyses have produced near-complete models of the mammalian complex, but leave the molecular principles of its long-range energy coupling mechanism open to debate. Here, we describe the 3.0-Å resolution cryo-EM structure of complex I from mouse heart mitochondria with a substrate-like inhibitor, piericidin A, bound in the ubiquinone-binding active site. We combine our structural analyses with both functional and computational studies to demonstrate competitive inhibitor binding poses and provide evidence that two inhibitor molecules bind end-to-end in the long substrate binding channel. Our findings reveal information about the mechanisms of inhibition and substrate reduction that are central for understanding the principles of energy transduction in mammalian complex I. The respiratory complex I (NADH:ubiquinone oxidoreductase) is a large redox-driven proton pump that initiates respiration in mitochondria. Here, the authors present the 3.0 Å cryo-EM structure of complex I from mouse heart mitochondria with the ubiquinone-analogue inhibitor piericidin A bound in the active site and with kinetic measurements and MD simulations they further show that this inhibitor acts competitively against the native ubiquinone-10 substrate.
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25
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Mühlbauer ME, Saura P, Nuber F, Di Luca A, Friedrich T, Kaila VRI. Water-Gated Proton Transfer Dynamics in Respiratory Complex I. J Am Chem Soc 2020; 142:13718-13728. [PMID: 32643371 PMCID: PMC7659035 DOI: 10.1021/jacs.0c02789] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
The respiratory complex I transduces
redox energy into an electrochemical
proton gradient in aerobic respiratory chains, powering energy-requiring
processes in the cell. However, despite recently resolved molecular
structures, the mechanism of this gigantic enzyme remains poorly understood.
By combining large-scale quantum and classical simulations with site-directed
mutagenesis and biophysical experiments, we show here how the conformational
state of buried ion-pairs and water molecules control the protonation
dynamics in the membrane domain of complex I and establish evolutionary
conserved long-range coupling elements. We suggest that an electrostatic
wave propagates in forward and reverse directions across the 200 Å
long membrane domain during enzyme turnover, without significant dissipation
of energy. Our findings demonstrate molecular principles that enable
efficient long-range proton–electron coupling (PCET) and how
perturbation of this PCET machinery may lead to development of mitochondrial
disease.
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Affiliation(s)
- Max E Mühlbauer
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.,Center for Integrated Protein Science Munich at the Department of Chemistry, Technical University of Munich, Lichtenbergstrasse 4, D85748 Garching, Germany
| | - Patricia Saura
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.,Center for Integrated Protein Science Munich at the Department of Chemistry, Technical University of Munich, Lichtenbergstrasse 4, D85748 Garching, Germany
| | - Franziska Nuber
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104 Freiburg, Germany
| | - Andrea Di Luca
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.,Center for Integrated Protein Science Munich at the Department of Chemistry, Technical University of Munich, Lichtenbergstrasse 4, D85748 Garching, Germany
| | - Thorsten Friedrich
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104 Freiburg, Germany
| | - Ville R I Kaila
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.,Center for Integrated Protein Science Munich at the Department of Chemistry, Technical University of Munich, Lichtenbergstrasse 4, D85748 Garching, Germany
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26
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Khaniya U, Gupta C, Cai X, Mao J, Kaur D, Zhang Y, Singharoy A, Gunner MR. Hydrogen bond network analysis reveals the pathway for the proton transfer in the E-channel of T. thermophilus Complex I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148240. [PMID: 32531220 DOI: 10.1016/j.bbabio.2020.148240] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Revised: 05/19/2020] [Accepted: 06/03/2020] [Indexed: 10/24/2022]
Abstract
Complex I, NADH-ubiquinone oxidoreductase, is the first enzyme in the mitochondrial and bacterial aerobic respiratory chain. It pumps four protons through four transiently open pathways from the high pH, negative, N-side of the membrane to the positive, P-side driven by the exergonic transfer of electrons from NADH to a quinone. Three protons transfer through subunits descended from antiporters, while the fourth, E-channel is unique. The path through the E-channel is determined by a network analysis of hydrogen bonded pathways obtained by Monte Carlo sampling of protonation states, polar hydrogen orientation and water occupancy. Input coordinates are derived from molecular dynamics trajectories comparing oxidized, reduced (dihydro) and no menaquinone-8 (MQ). A complex proton transfer path from the N- to the P-side is found consisting of six clusters of highly connected hydrogen-bonded residues. The network connectivity depends on the presence of quinone and its redox state, supporting a role for this cofactor in coupling electron and proton transfers. The N-side is more organized with MQ-bound complex I facilitating proton entry, while the P-side is more connected in the apo-protein, facilitating proton exit. Subunit Nqo8 forms the core of the E channel; Nqo4 provides the N-side entry, Nqo7 and then Nqo10 join the pathway in the middle, while Nqo11 contributes to the P-side exit.
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Affiliation(s)
- Umesh Khaniya
- Department of Physics, City College of New York, New York 10031, USA; Department of Physics, The Graduate Center, City University of New York, New York 10016, USA
| | - Chitrak Gupta
- School of Molecular Sciences, Arizona State University, Tempe, AZ, USA; Biodesign Institute, Arizona State University, Tempe, AZ, USA
| | - Xiuhong Cai
- Department of Physics, City College of New York, New York 10031, USA; Department of Physics, The Graduate Center, City University of New York, New York 10016, USA
| | - Junjun Mao
- Department of Physics, City College of New York, New York 10031, USA
| | - Divya Kaur
- Department of Physics, City College of New York, New York 10031, USA; Department of Chemistry, The Graduate Center, City University of New York, New York 10016, USA
| | - Yingying Zhang
- Department of Physics, City College of New York, New York 10031, USA; Department of Physics, The Graduate Center, City University of New York, New York 10016, USA
| | - Abhishek Singharoy
- School of Molecular Sciences, Arizona State University, Tempe, AZ, USA; Biodesign Institute, Arizona State University, Tempe, AZ, USA
| | - M R Gunner
- Department of Physics, City College of New York, New York 10031, USA; Department of Physics, The Graduate Center, City University of New York, New York 10016, USA; Department of Chemistry, The Graduate Center, City University of New York, New York 10016, USA.
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27
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Wright JJ, Fedor JG, Hirst J, Roessler MM. Using a chimeric respiratory chain and EPR spectroscopy to determine the origin of semiquinone species previously assigned to mitochondrial complex I. BMC Biol 2020; 18:54. [PMID: 32429970 PMCID: PMC7238650 DOI: 10.1186/s12915-020-00768-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 03/11/2020] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND For decades, semiquinone intermediates have been suggested to play an essential role in catalysis by one of the most enigmatic proton-pumping enzymes, respiratory complex I, and different mechanisms have been proposed on their basis. However, the difficulty in investigating complex I semiquinones, due to the many different enzymes embedded in the inner mitochondrial membrane, has resulted in an ambiguous picture and no consensus. RESULTS In this paper, we re-examine the highly debated origin of semiquinone species in mitochondrial membranes using a novel approach. Our combination of a semi-artificial chimeric respiratory chain with pulse EPR spectroscopy (HYSCORE) has enabled us to conclude, unambiguously and for the first time, that the majority of the semiquinones observed in mitochondrial membranes originate from complex III. We also identify a minor contribution from complex II. CONCLUSIONS We are unable to attribute any semiquinone signals unambiguously to complex I and, reconciling our observations with much of the previous literature, conclude that they are likely to have been misattributed to it. We note that, for this earlier work, the tools we have relied on here to deconvolute overlapping EPR signals were not available. Proposals for the mechanism of complex I based on the EPR signals of semiquinone species observed in mitochondrial membranes should thus be treated with caution until future work has succeeded in isolating any complex I semiquinone EPR spectroscopic signatures present.
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Affiliation(s)
- John J Wright
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, CB2 0XY, UK
| | - Justin G Fedor
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, CB2 0XY, UK
| | - Judy Hirst
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, CB2 0XY, UK
| | - Maxie M Roessler
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London, W12 0BZ, UK.
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28
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Gupta C, Khaniya U, Chan CK, Dehez F, Shekhar M, Gunner MR, Sazanov L, Chipot C, Singharoy A. Charge Transfer and Chemo-Mechanical Coupling in Respiratory Complex I. J Am Chem Soc 2020; 142:9220-9230. [PMID: 32347721 DOI: 10.1021/jacs.9b13450] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The mitochondrial respiratory chain, formed by five protein complexes, utilizes energy from catabolic processes to synthesize ATP. Complex I, the first and the largest protein complex of the chain, harvests electrons from NADH to reduce quinone, while pumping protons across the mitochondrial membrane. Detailed knowledge of the working principle of such coupled charge-transfer processes remains, however, fragmentary due to bottlenecks in understanding redox-driven conformational transitions and their interplay with the hydrated proton pathways. Complex I from Thermus thermophilus encases 16 subunits with nine iron-sulfur clusters, reduced by electrons from NADH. Here, employing the latest crystal structure of T. thermophilus complex I, we have used microsecond-scale molecular dynamics simulations to study the chemo-mechanical coupling between redox changes of the iron-sulfur clusters and conformational transitions across complex I. First, we identify the redox switches within complex I, which allosterically couple the dynamics of the quinone binding pocket to the site of NADH reduction. Second, our free-energy calculations reveal that the affinity of the quinone, specifically menaquinone, for the binding-site is higher than that of its reduced, menaquinol form-a design essential for menaquinol release. Remarkably, the barriers to diffusive menaquinone dynamics are lesser than that of the more ubiquitous ubiquinone, and the naphthoquinone headgroup of the former furnishes stronger binding interactions with the pocket, favoring menaquinone for charge transport in T. thermophilus. Our computations are consistent with experimentally validated mutations and hierarchize the key residues into three functional classes, identifying new mutation targets. Third, long-range hydrogen-bond networks connecting the quinone-binding site to the transmembrane subunits are found to be responsible for proton pumping. Put together, the simulations reveal the molecular design principles linking redox reactions to quinone turnover to proton translocation in complex I.
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Affiliation(s)
- Chitrak Gupta
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85281, United States.,Biodesign Institute, Arizona State University, Tempe, Arizona 85281, United States
| | - Umesh Khaniya
- Department of Physics, City College of New York, New York, New York 10031, United States.,Department of Physics, City University of New York, New York, New York 10017, United States
| | - Chun Kit Chan
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | | | - Mrinal Shekhar
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - M R Gunner
- Department of Physics, City College of New York, New York, New York 10031, United States.,Department of Physics, City University of New York, New York, New York 10017, United States
| | - Leonid Sazanov
- Institute of Science and Technology, 3400 Klosterneuburg, Austria
| | - Christophe Chipot
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,University of Lorraine, Nancy 54000, France
| | - Abhishek Singharoy
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85281, United States.,Biodesign Institute, Arizona State University, Tempe, Arizona 85281, United States
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29
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Murai M. Exploring the binding pocket of quinone/inhibitors in mitochondrial respiratory complex I by chemical biology approaches. Biosci Biotechnol Biochem 2020; 84:1322-1331. [PMID: 32264779 DOI: 10.1080/09168451.2020.1747974] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
NADH-quinone oxidoreductase (respiratory complex I) is a key player in mitochondrial energy metabolism. The enzyme couples electron transfer from NADH to quinone with the translocation of protons across the membrane, providing a major proton-motive force that drives ATP synthesis. Recently, X-ray crystallography and cryo-electron microscopy provided further insights into the structure and functions of the enzyme. However, little is known about the mechanism of quinone reduction, which is a crucial step in the energy coupling process. A variety of complex I inhibitors targeting the quinone-binding site have been indispensable tools for mechanistic studies on the enzyme. Using biorationally designed inhibitor probes, the author has accumulated a large amount of experimental data characterizing the actions of complex I inhibitors. On the basis of comprehensive interpretations of the data, the author reviews the structural features of the binding pocket of quinone/inhibitors in bovine mitochondrial complex I. ABBREVIATIONS ATP: adenosine triphosphate; BODIPY: boron dipyrromethene; complex I: proton-translocating NADH-quinone oxidoreductase; DIBO: dibenzocyclooctyne; EM: electron microscopy; FeS: iron-sulfur; FMN: flavin adenine mononucleotide; LDT: ligand-directed tosylate; NADH: nicotinamide adenine dinucleotide; ROS: reactive oxygen species; SMP: submitochondrial particle; TAMRA: 6-carboxy-N,N,N',N'-tetramethylrhodamine; THF: tetrahydrofuran; TMH: transmembrane helix.
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Affiliation(s)
- Masatoshi Murai
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University , Kyoto, Japan
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30
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Saura P, Röpke M, Gamiz-Hernandez AP, Kaila VRI. Quantum Chemical and QM/MM Models in Biochemistry. Methods Mol Biol 2020; 2022:75-104. [PMID: 31396900 DOI: 10.1007/978-1-4939-9608-7_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
Quantum chemical (QC) calculations provide a basis for deriving a microscopic understanding of enzymes and photobiological systems. Here we describe how QC models can be used to explore the electronic structure, dynamics, and energetics of biomolecules. We introduce the hybrid quantum mechanics/classical mechanics (QM/MM) approach, where a quantum mechanically described system of interest is embedded in a classically described force field representation of the biochemical surroundings. We also discuss the QM cluster model approach, as well as embedding theories, that provide complementary methodologies to model quantum mechanical effects in biomolecules. The chapter also provides some practical guides for building quantum biochemical models using the quinone reduction catalysis in respiratory complex I and a model reaction in solution as examples.
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Affiliation(s)
- Patricia Saura
- Department Chemie, Technische Universität München, Garching, Germany
| | - Michael Röpke
- Department Chemie, Technische Universität München, Garching, Germany
| | | | - Ville R I Kaila
- Department Chemie, Technische Universität München, Garching, Germany.
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31
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Uno S, Masuya T, Shinzawa-Itoh K, Lasham J, Haapanen O, Shiba T, Inaoka DK, Sharma V, Murai M, Miyoshi H. Oversized ubiquinones as molecular probes for structural dynamics of the ubiquinone reaction site in mitochondrial respiratory complex I. J Biol Chem 2020; 295:2449-2463. [PMID: 31953326 DOI: 10.1074/jbc.ra119.012347] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/15/2020] [Indexed: 12/18/2022] Open
Abstract
NADH-quinone oxidoreductase (complex I) couples electron transfer from NADH to quinone with proton translocation across the membrane. Quinone reduction is a key step for energy transmission from the site of quinone reduction to the remotely located proton-pumping machinery of the enzyme. Although structural biology studies have proposed the existence of a long and narrow quinone-access channel, the physiological relevance of this channel remains debatable. We investigated here whether complex I in bovine heart submitochondrial particles (SMPs) can catalytically reduce a series of oversized ubiquinones (OS-UQs), which are highly unlikely to transit the narrow channel because their side chain includes a bulky "block" that is ∼13 Å across. We found that some OS-UQs function as efficient electron acceptors from complex I, accepting electrons with an efficiency comparable with ubiquinone-2. The catalytic reduction and proton translocation coupled with this reduction were completely inhibited by different quinone-site inhibitors, indicating that the reduction of OS-UQs takes place at the physiological reaction site for ubiquinone. Notably, the proton-translocating efficiencies of OS-UQs significantly varied depending on their side-chain structures, suggesting that the reaction characteristics of OS-UQs affect the predicted structural changes of the quinone reaction site required for triggering proton translocation. These results are difficult to reconcile with the current channel model; rather, the access path for ubiquinone may be open to allow OS-UQs to access the reaction site. Nevertheless, contrary to the observations in SMPs, OS-UQs were not catalytically reduced by isolated complex I reconstituted into liposomes. We discuss possible reasons for these contradictory results.
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Affiliation(s)
- Shinpei Uno
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Takahiro Masuya
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Kyoko Shinzawa-Itoh
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
| | - Jonathan Lasham
- Department of Physics, University of Helsinki, FI-00014 Helsinki, Finland
| | - Outi Haapanen
- Department of Physics, University of Helsinki, FI-00014 Helsinki, Finland
| | - Tomoo Shiba
- Department of Applied Biology, Graduate School of Science and Technology, Kyoto Institute of Technology, Kyoto 606-8585, Japan
| | - Daniel Ken Inaoka
- Department of Molecular Infection Dynamics, Institute of Tropical Medicine (NEKKEN); School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki 852-8523, Japan
| | - Vivek Sharma
- Department of Physics, University of Helsinki, FI-00014 Helsinki, Finland; Institute of Biotechnology, University of Helsinki, FI-00014 Helsinki, Finland
| | - Masatoshi Murai
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Hideto Miyoshi
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
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32
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Kaila VRI. Long-range proton-coupled electron transfer in biological energy conversion: towards mechanistic understanding of respiratory complex I. J R Soc Interface 2019; 15:rsif.2017.0916. [PMID: 29643224 PMCID: PMC5938582 DOI: 10.1098/rsif.2017.0916] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 03/13/2018] [Indexed: 12/20/2022] Open
Abstract
Biological energy conversion is driven by efficient enzymes that capture, store and transfer protons and electrons across large distances. Recent advances in structural biology have provided atomic-scale blueprints of these types of remarkable molecular machinery, which together with biochemical, biophysical and computational experiments allow us to derive detailed energy transduction mechanisms for the first time. Here, I present one of the most intricate and least understood types of biological energy conversion machinery, the respiratory complex I, and how its redox-driven proton-pump catalyses charge transfer across approximately 300 Å distances. After discussing the functional elements of complex I, a putative mechanistic model for its action-at-a-distance effect is presented, and functional parallels are drawn to other redox- and light-driven ion pumps.
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Affiliation(s)
- Ville R I Kaila
- Department of Chemistry, Technische Universität München, Lichtenbergstr. 4, Garching, Germany
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33
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Hoias Teixeira M, Menegon Arantes G. Balanced internal hydration discriminates substrate binding to respiratory complex I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1860:541-548. [DOI: 10.1016/j.bbabio.2019.05.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 05/16/2019] [Accepted: 05/28/2019] [Indexed: 12/16/2022]
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34
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Hagras MA, Stuchebrukhov AA. Concerted Two-Electron Reduction of Ubiquinone in Respiratory Complex I. J Phys Chem B 2019; 123:5265-5273. [DOI: 10.1021/acs.jpcb.9b04082] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Muhammad A. Hagras
- Department of Chemistry, University of California Davis, One Shields Avenue, Davis, California 95616, United States
| | - Alexei A. Stuchebrukhov
- Department of Chemistry, University of California Davis, One Shields Avenue, Davis, California 95616, United States
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35
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Haapanen O, Djurabekova A, Sharma V. Role of Second Quinone Binding Site in Proton Pumping by Respiratory Complex I. Front Chem 2019; 7:221. [PMID: 31024903 PMCID: PMC6465577 DOI: 10.3389/fchem.2019.00221] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 03/21/2019] [Indexed: 12/22/2022] Open
Abstract
Respiratory complex I performs the reduction of quinone (Q) to quinol (QH2) and pumps protons across the membrane. Structural data on complex I have provided spectacular insights into the electron and proton transfer paths, as well as into the long (~30 Å) and unique substrate binding channel. However, due to missing structural information on Q binding modes, it remains unclear how Q reduction drives long range (~20 nm) redox-coupled proton pumping in complex I. Here we applied multiscale computational approaches to study the dynamics and redox chemistry of Q and QH2. Based on tens of microseconds of atomistic molecular dynamics (MD) simulations of bacterial and mitochondrial complex I, we find that the dynamics of Q is remarkably rapid and it diffuses from the N2 binding site to another stable site near the entrance of the Q channel in microseconds. Analysis of simulation trajectories also reveal the presence of yet another Q binding site 25–30 Å from the N2 center, which is in remarkable agreement with the electron density observed in recent cryo electron microscopy structure of complex I from Yarrowia lipolytica. Quantum chemical computations on the two Q binding sites closer to the entrance of the Q tunnel reveal redox-coupled protonation reactions that may be important in driving the proton pump of complex I.
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Affiliation(s)
- Outi Haapanen
- Department of Physics, University of Helsinki, Helsinki, Finland
| | | | - Vivek Sharma
- Department of Physics, University of Helsinki, Helsinki, Finland.,Institute of Biotechnology, University of Helsinki, Helsinki, Finland
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36
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Pernil R, Schleiff E. Metalloproteins in the Biology of Heterocysts. Life (Basel) 2019; 9:E32. [PMID: 30987221 PMCID: PMC6616624 DOI: 10.3390/life9020032] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 03/18/2019] [Accepted: 03/28/2019] [Indexed: 12/15/2022] Open
Abstract
Cyanobacteria are photoautotrophic microorganisms present in almost all ecologically niches on Earth. They exist as single-cell or filamentous forms and the latter often contain specialized cells for N₂ fixation known as heterocysts. Heterocysts arise from photosynthetic active vegetative cells by multiple morphological and physiological rearrangements including the absence of O₂ evolution and CO₂ fixation. The key function of this cell type is carried out by the metalloprotein complex known as nitrogenase. Additionally, many other important processes in heterocysts also depend on metalloproteins. This leads to a high metal demand exceeding the one of other bacteria in content and concentration during heterocyst development and in mature heterocysts. This review provides an overview on the current knowledge of the transition metals and metalloproteins required by heterocysts in heterocyst-forming cyanobacteria. It discusses the molecular, physiological, and physicochemical properties of metalloproteins involved in N₂ fixation, H₂ metabolism, electron transport chains, oxidative stress management, storage, energy metabolism, and metabolic networks in the diazotrophic filament. This provides a detailed and comprehensive picture on the heterocyst demands for Fe, Cu, Mo, Ni, Mn, V, and Zn as cofactors for metalloproteins and highlights the importance of such metalloproteins for the biology of cyanobacterial heterocysts.
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Affiliation(s)
- Rafael Pernil
- Institute for Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue-Straβe 9, 60438 Frankfurt am Main, Germany.
| | - Enrico Schleiff
- Institute for Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue-Straβe 9, 60438 Frankfurt am Main, Germany.
- Frankfurt Institute for Advanced Studies, Ruth-Moufang-Straße 1, 60438 Frankfurt am Main, Germany.
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Max-von-Laue-Straβe 15, 60438 Frankfurt am Main, Germany.
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37
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Saura P, Kaila VRI. Energetics and Dynamics of Proton-Coupled Electron Transfer in the NADH/FMN Site of Respiratory Complex I. J Am Chem Soc 2019; 141:5710-5719. [PMID: 30873834 PMCID: PMC6890364 DOI: 10.1021/jacs.8b11059] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Complex I functions as an initial electron acceptor in aerobic respiratory chains that reduces quinone and pumps protons across a biological membrane. This remarkable charge transfer process extends ca. 300 Å and it is initiated by a poorly understood proton-coupled electron transfer (PCET) reaction between nicotinamide adenine dinucleotide (NADH) and a protein-bound flavin (FMN) cofactor. We combine here large-scale density functional theory calculations and quantum/classical models with atomistic molecular dynamics simulations to probe the energetics and dynamics of the NADH-driven PCET reaction in complex I. We find that the reaction takes place by concerted hydrogen atom (H•) transfer that couples to an electron transfer (eT) between the aromatic ring systems of the cofactors and further triggers reduction of the nearby FeS centers. In bacterial, Escherichia coli-like complex I isoforms, reduction of the N1a FeS center increases the binding affinity of the oxidized NAD+ that prevents the nucleotide from leaving prematurely. This electrostatic trapping could provide a protective gating mechanism against reactive oxygen species formation. We also find that proton transfer from the transient FMNH• to a nearby conserved glutamate (Glu97) residue favors eT from N1a onward along the FeS chain and modulates the binding of a new NADH molecule. The PCET in complex I isoforms with low-potential N1a centers is also discussed. On the basis of our combined results, we propose a putative mechanistic model for the NADH-driven proton/electron-transfer reaction in complex I.
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Affiliation(s)
- Patricia Saura
- Department of Chemistry , Technical University of Munich (TUM) , Lichtenbergstrasse 4 , Garching D-85747 , Germany
| | - Ville R I Kaila
- Department of Chemistry , Technical University of Munich (TUM) , Lichtenbergstrasse 4 , Garching D-85747 , Germany
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38
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Saura P, Kaila VRI. Molecular dynamics and structural models of the cyanobacterial NDH-1 complex. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2019; 1860:201-208. [PMID: 30448269 PMCID: PMC6358722 DOI: 10.1016/j.bbabio.2018.11.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 10/30/2018] [Accepted: 11/07/2018] [Indexed: 02/07/2023]
Abstract
NDH-1 is a gigantic redox-driven proton pump linked with respiration and cyclic electron flow in cyanobacterial cells. Based on experimentally resolved X-ray and cryo-EM structures of the respiratory complex I, we derive here molecular models of two isoforms of the cyanobacterial NDH-1 complex involved in redox-driven proton pumping (NDH-1L) and CO2-fixation (NDH-1MS). Our models show distinct structural and dynamic similarities to the core architecture of the bacterial and mammalian respiratory complex I. We identify putative plastoquinone-binding sites that are coupled by an electrostatic wire to the proton pumping elements in the membrane domain of the enzyme. Molecular simulations suggest that the NDH-1L isoform undergoes large-scale hydration changes that support proton-pumping within antiporter-like subunits, whereas the terminal subunit of the NDH-1MS isoform lacks such structural motifs. Our work provides a putative molecular blueprint for the complex I-analogue in the photosynthetic energy transduction machinery and demonstrates that general mechanistic features of the long-range proton-pumping machinery are evolutionary conserved in the complex I-superfamily.
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Affiliation(s)
- Patricia Saura
- Department of Chemistry, Technical University of Munich (TUM), Lichtenbergstraße 4, Garching D-85747, Germany
| | - Ville R I Kaila
- Department of Chemistry, Technical University of Munich (TUM), Lichtenbergstraße 4, Garching D-85747, Germany.
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39
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Zhang Y, Xu W, Fan J, Zhang L, Pang J, Wang J. New cathodic peak of quinone caused by the ultrafast diffusion of protons in unbuffered aqueous solution. J Electroanal Chem (Lausanne) 2019. [DOI: 10.1016/j.jelechem.2018.11.043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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40
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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.
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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
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41
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Abstract
Complex I couples the free energy released from quinone (Q) reduction to pump protons across the biological membrane in the respiratory chains of mitochondria and many bacteria. The Q reduction site is separated by a large distance from the proton-pumping membrane domain. To address the molecular mechanism of this long-range proton-electron coupling, we perform here full atomistic molecular dynamics simulations, free energy calculations, and continuum electrostatics calculations on complex I from Thermus thermophilus We show that the dynamics of Q is redox-state-dependent, and that quinol, QH2, moves out of its reduction site and into a site in the Q tunnel that is occupied by a Q analog in a crystal structure of Yarrowia lipolytica We also identify a second Q-binding site near the opening of the Q tunnel in the membrane domain, where the Q headgroup forms strong interactions with a cluster of aromatic and charged residues, while the Q tail resides in the lipid membrane. We estimate the effective diffusion coefficient of Q in the tunnel, and in turn the characteristic time for Q to reach the active site and for QH2 to escape to the membrane. Our simulations show that Q moves along the Q tunnel in a redox-state-dependent manner, with distinct binding sites formed by conserved residue clusters. The motion of Q to these binding sites is proposed to be coupled to the proton-pumping machinery in complex I.
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42
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A modeling and simulation perspective on the mechanism and function of respiratory complex I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:510-523. [DOI: 10.1016/j.bbabio.2018.04.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 04/03/2018] [Accepted: 04/10/2018] [Indexed: 12/12/2022]
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43
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Agip ANA, Blaza JN, Bridges HR, Viscomi C, Rawson S, Muench SP, Hirst J. Cryo-EM structures of complex I from mouse heart mitochondria in two biochemically defined states. Nat Struct Mol Biol 2018; 25:548-556. [PMID: 29915388 PMCID: PMC6054875 DOI: 10.1038/s41594-018-0073-1] [Citation(s) in RCA: 163] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 04/26/2018] [Indexed: 02/02/2023]
Abstract
Complex I (NADH:ubiquinone oxidoreductase) uses the reducing potential of NADH to drive protons across the energy-transducing inner membrane and power oxidative phosphorylation in mammalian mitochondria. Recent cryo-EM analyses have produced near-complete models of all 45 subunits in the bovine, ovine and porcine complexes and have identified two states relevant to complex I in ischemia-reperfusion injury. Here, we describe the 3.3-Å structure of complex I from mouse heart mitochondria, a biomedically relevant model system, in the 'active' state. We reveal a nucleotide bound in subunit NDUFA10, a nucleoside kinase homolog, and define mechanistically critical elements in the mammalian enzyme. By comparisons with a 3.9-Å structure of the 'deactive' state and with known bacterial structures, we identify differences in helical geometry in the membrane domain that occur upon activation or that alter the positions of catalytically important charged residues. Our results demonstrate the capability of cryo-EM analyses to challenge and develop mechanistic models for mammalian complex I.
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Affiliation(s)
- Ahmed-Noor A Agip
- The Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - James N Blaza
- The Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Hannah R Bridges
- The Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Carlo Viscomi
- The Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Shaun Rawson
- School of Biomedical Sciences, Faculty of Biological Sciences and Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, UK
| | - Stephen P Muench
- School of Biomedical Sciences, Faculty of Biological Sciences and Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, UK
| | - Judy Hirst
- The Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK.
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Di Luca A, Mühlbauer ME, Saura P, Kaila VRI. How inter-subunit contacts in the membrane domain of complex I affect proton transfer energetics. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:734-741. [PMID: 29883589 DOI: 10.1016/j.bbabio.2018.06.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 05/08/2018] [Accepted: 06/02/2018] [Indexed: 10/14/2022]
Abstract
The respiratory complex I is a redox-driven proton pump that employs the free energy released from quinone reduction to pump protons across its complete ca. 200 Å wide membrane domain. Despite recently resolved structures and molecular simulations, the exact mechanism for the proton transport process remains unclear. Here we combine large-scale molecular simulations with quantum chemical density functional theory (DFT) models to study how contacts between neighboring antiporter-like subunits in the membrane domain of complex I affect the proton transfer energetics. Our combined results suggest that opening of conserved Lys/Glu ion pairs within each antiporter-like subunit modulates the barrier for the lateral proton transfer reactions. Our work provides a mechanistic suggestion for key coupling effects in the long-range force propagation process of complex I.
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Affiliation(s)
- Andrea Di Luca
- Department Chemie, Technische Universität München, Lichtenbergstr. 4, Garching, D-85747, Germany
| | - Max E Mühlbauer
- Department Chemie, Technische Universität München, Lichtenbergstr. 4, Garching, D-85747, Germany
| | - Patricia Saura
- Department Chemie, Technische Universität München, Lichtenbergstr. 4, Garching, D-85747, Germany
| | - Ville R I Kaila
- Department Chemie, Technische Universität München, Lichtenbergstr. 4, Garching, D-85747, Germany.
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