1
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Rigobello L, Lugli F, Caporali L, Bartocci A, Fadanni J, Zerbetto F, Iommarini L, Carelli V, Ghelli AM, Musiani F. A computational study to assess the pathogenicity of single or combinations of missense variants on respiratory complex I. Int J Biol Macromol 2024; 273:133086. [PMID: 38871105 DOI: 10.1016/j.ijbiomac.2024.133086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 06/07/2024] [Accepted: 06/09/2024] [Indexed: 06/15/2024]
Abstract
Variants found in the respiratory complex I (CI) subunit genes encoded by mitochondrial DNA can cause severe genetic diseases. However, it is difficult to establish a priori whether a single or a combination of CI variants may impact oxidative phosphorylation. Here we propose a computational approach based on coarse-grained molecular dynamics simulations aimed at investigating new CI variants. One of the primary CI variants associated with the Leber hereditary optic neuropathy (m.14484T>C/MT-ND6) was used as a test case and was investigated alone or in combination with two additional rare CI variants whose role remains uncertain. We found that the primary variant positioned in the E-channel region, which is fundamental for CI function, stiffens the enzyme dynamics. Moreover, a new mechanism for the transition between π- and α-conformation in the helix carrying the primary variant is proposed. This may have implications for the E-channel opening/closing mechanism. Finally, our findings show that one of the rare variants, located next to the primary one, further worsens the stiffening, while the other rare variant does not affect CI function. This approach may be extended to other variants candidate to exert a pathogenic impact on CI dynamics, or to investigate the interaction of multiple variants.
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Affiliation(s)
- Laura Rigobello
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna I-40127, Italy
| | - Francesca Lugli
- Department of Chemistry "Giacomo Ciamician", University of Bologna, Bologna I-40126, Italy.
| | - Leonardo Caporali
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna I-40124, Italy
| | - Alessio Bartocci
- Department of Physics, University of Trento, Trento I-38123, Italy; INFN-TIFPA, Trento Institute for Fundamental Physics and Applications, Trento I-38123, Italy
| | - Jacopo Fadanni
- Department of Chemistry "Giacomo Ciamician", University of Bologna, Bologna I-40126, Italy
| | - Francesco Zerbetto
- Department of Chemistry "Giacomo Ciamician", University of Bologna, Bologna I-40126, Italy
| | - Luisa Iommarini
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna I-40127, Italy
| | - Valerio Carelli
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna I-40124, Italy; Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna I-40123, Italy
| | - Anna Maria Ghelli
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna I-40127, Italy; IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna I-40124, Italy
| | - Francesco Musiani
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna I-40127, Italy.
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2
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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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3
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Lasham J, Djurabekova A, Zickermann V, Vonck J, Sharma V. Role of Protonation States in the Stability of Molecular Dynamics Simulations of High-Resolution Membrane Protein Structures. J Phys Chem B 2024; 128:2304-2316. [PMID: 38430110 DOI: 10.1021/acs.jpcb.3c07421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2024]
Abstract
Classical molecular dynamics (MD) simulations provide unmatched spatial and time resolution of protein structure and function. However, the accuracy of MD simulations often depends on the quality of force field parameters and the time scale of sampling. Another limitation of conventional MD simulations is that the protonation states of titratable amino acid residues remain fixed during simulations, even though protonation state changes coupled to conformational dynamics are central to protein function. Due to the uncertainty in selecting protonation states, classical MD simulations are sometimes performed with all amino acids modeled in their standard charged states at pH 7. Here, we performed and analyzed classical MD simulations on high-resolution cryo-EM structures of two large membrane proteins that transfer protons by catalyzing protonation/deprotonation reactions. In simulations performed with titratable amino acids modeled in their standard protonation (charged) states, the structure diverges far from its starting conformation. In comparison, MD simulations performed with predetermined protonation states of amino acid residues reproduce the structural conformation, protein hydration, and protein-water and protein-protein interactions of the structure much better. The results support the notion that it is crucial to perform basic protonation state calculations, especially on structures where protonation changes play an important functional role, prior to the launch of any conventional MD simulations. Furthermore, the combined approach of fast protonation state prediction and MD simulations can provide valuable information about the charge states of amino acids in the cryo-EM sample. Even though accurate prediction of protonation states in proteinaceous environments currently remains a challenge, we introduce an approach of combining pKa prediction with cryo-EM density map analysis that helps in improving not only the protonation state predictions but also the atomic modeling of density data.
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Affiliation(s)
- Jonathan Lasham
- Department of Physics, University of Helsinki, 00014 Helsinki, Finland
| | - Amina Djurabekova
- Department of Physics, University of Helsinki, 00014 Helsinki, Finland
| | - Volker Zickermann
- Institute of Biochemistry II, University Hospital, Goethe University, 60590 Frankfurt am Main, Germany
- Centre for Biomolecular Magnetic Resonance, Institute for Biophysical Chemistry, Goethe University, 60438 Frankfurt am Main, Germany
| | - Janet Vonck
- Department of Structural Biology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Vivek Sharma
- Department of Physics, University of Helsinki, 00014 Helsinki, Finland
- HiLIFE Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
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4
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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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5
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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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6
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Zdorevskyi O, Djurabekova A, Lasham J, Sharma V. Horizontal proton transfer across the antiporter-like subunits in mitochondrial respiratory complex I. Chem Sci 2023; 14:6309-6318. [PMID: 37325138 PMCID: PMC10266447 DOI: 10.1039/d3sc01427d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Accepted: 05/09/2023] [Indexed: 06/17/2023] Open
Abstract
Respiratory complex I is a redox-driven proton pump contributing to about 40% of total proton motive force required for mitochondrial ATP generation. Recent high-resolution cryo-EM structural data revealed the positions of several water molecules in the membrane domain of the large enzyme complex. However, it remains unclear how protons flow in the membrane-bound antiporter-like subunits of complex I. Here, we performed multiscale computer simulations on high-resolution structural data to model explicit proton transfer processes in the ND2 subunit of complex I. Our results show protons can travel the entire width of antiporter-like subunits, including at the subunit-subunit interface, parallel to the membrane. We identify a previously unrecognized role of conserved tyrosine residues in catalyzing horizontal proton transfer, and that long-range electrostatic effects assist in reducing energetic barriers of proton transfer dynamics. Results from our simulations warrant a revision in several prevailing proton pumping models of respiratory complex I.
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Affiliation(s)
| | | | - Jonathan Lasham
- Department of Physics, University of Helsinki Helsinki Finland
| | - Vivek Sharma
- Department of Physics, University of Helsinki Helsinki Finland
- HiLIFE Institute of Biotechnology, University of Helsinki Helsinki Finland
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7
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Abstract
We present a brief review of the mitochondrial respiratory chain with emphasis on complexes I, III and IV, which contribute to the generation of protonmotive force across the inner mitochondrial membrane, and drive the synthesis of ATP by the process called oxidative phosphorylation. The basic structural and functional details of these complexes are discussed. In addition, we briefly review the information on the so-called supercomplexes, aggregates of complexes I-IV, and summarize basic physiological aspects of cell respiration.
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Affiliation(s)
- Mårten Wikström
- HiLife Institute of Biotechnology, University of Helsinki, Biocenter, Viikinkaari, Helsinki, Finland.
| | - Cristina Pecorilla
- Department of Physics, University of Helsinki, Gustaf Hällströmin katu, Helsinki, Finland
| | - Vivek Sharma
- HiLife Institute of Biotechnology, University of Helsinki, Biocenter, Viikinkaari, Helsinki, Finland; Department of Physics, University of Helsinki, Gustaf Hällströmin katu, Helsinki, Finland
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8
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Tunnel dynamics of quinone derivatives and its coupling to protein conformational rearrangements in respiratory complex I. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2023; 1864:148951. [PMID: 36509126 DOI: 10.1016/j.bbabio.2022.148951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 11/30/2022] [Accepted: 12/02/2022] [Indexed: 12/13/2022]
Abstract
Respiratory complex I in mitochondria and bacteria catalyzes the transfer of electrons from NADH to quinone (Q). The free energy available from the reaction is used to pump protons and to establish a membrane proton electrochemical gradient, which drives ATP synthesis. Even though several high-resolution structures of complex I have been resolved, how Q reduction is linked with proton pumping, remains unknown. Here, microsecond long molecular dynamics (MD) simulations were performed on Yarrowia lipolytica complex I structures where Q molecules have been resolved in the ~30 Å long Q tunnel. MD simulations of several different redox/protonation states of Q reveal the coupling between the Q dynamics and the restructuring of conserved loops and ion pairs. Oxidized quinone stabilizes towards the N2 FeS cluster, a binding mode not previously described in Yarrowia lipolytica complex I structures. On the other hand, reduced (and protonated) species tend to diffuse towards the Q binding sites closer to the tunnel entrance. Mechanistic and physiological relevance of these results are discussed.
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9
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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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10
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Respiratory complex I with charge symmetry in the membrane arm pumps protons. Proc Natl Acad Sci U S A 2022; 119:e2123090119. [PMID: 35759670 PMCID: PMC9271201 DOI: 10.1073/pnas.2123090119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Respiratory complex I is a central enzyme of cellular energy metabolism coupling quinone reduction with proton translocation. Its mechanism, especially concerning proton translocation, remains enigmatic. Three homologous subunits that contain a conserved pattern of charged and polar amino acid residues catalyze proton translocation. Strikingly, the central subunit NuoM contains a conserved glutamate residue at a position where conserved lysine residues are found in the other two subunits, resulting in a charge asymmetry discussed to be essential for proton translocation. We found that the respective glutamate to lysine mutation in Escherichia coli complex I lowers the amount of protons translocated per electron transferred by one-quarter. These data clarify the discussion about possible mechanisms of proton translocation by complex I. Energy-converting NADH:ubiquinone oxidoreductase, respiratory complex I, is essential for cellular energy metabolism coupling NADH oxidation to proton translocation. The mechanism of proton translocation by complex I is still under debate. Its membrane arm contains an unusual central axis of polar and charged amino acid residues connecting the quinone binding site with the antiporter-type subunits NuoL, NuoM, and NuoN, proposed to catalyze proton translocation. Quinone chemistry probably causes conformational changes and electrostatic interactions that are propagated through these subunits by a conserved pattern of predominantly lysine, histidine, and glutamate residues. These conserved residues are thought to transfer protons along and across the membrane arm. The distinct charge distribution in the membrane arm is a prerequisite for proton translocation. Remarkably, the central subunit NuoM contains a conserved glutamate residue in a position that is taken by a lysine residue in the two other antiporter-type subunits. It was proposed that this charge asymmetry is essential for proton translocation, as it should enable NuoM to operate asynchronously with NuoL and NuoN. Accordingly, we exchanged the conserved glutamate in NuoM for a lysine residue, introducing charge symmetry in the membrane arm. The stably assembled variant pumps protons across the membrane, but with a diminished H+/e− stoichiometry of 1.5. Thus, charge asymmetry is not essential for proton translocation by complex I, casting doubts on the suggestion of an asynchronous operation of NuoL, NuoM, and NuoN. Furthermore, our data emphasize the importance of a balanced charge distribution in the protein for directional proton transfer.
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11
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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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12
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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
![]()
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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13
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Mühlbauer ME, Gamiz-Hernandez AP, Kaila VRI. Functional Dynamics of an Ancient Membrane-Bound Hydrogenase. J Am Chem Soc 2021; 143:20873-20883. [PMID: 34846879 PMCID: PMC8679088 DOI: 10.1021/jacs.1c09356] [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] [Indexed: 01/08/2023]
Abstract
![]()
The membrane-bound
hydrogenase (Mbh) is a redox-driven Na+/H+ transporter
that employs the energy from hydrogen
gas (H2) production to catalyze proton pumping and Na+/H+ exchange across cytoplasmic membranes of archaea.
Despite a recently resolved structure of this ancient energy-transducing
enzyme [Yu et al. Cell2018, 173, 1636–1649], the molecular principles of its
redox-driven ion-transport mechanism remain puzzling and of major
interest for understanding bioenergetic principles of early cells.
Here we use atomistic molecular dynamics (MD) simulations in combination
with data clustering methods and quantum chemical calculations to
probe principles underlying proton reduction as well as proton and
sodium transport in Mbh from the hyperthermophilic archaeon Pyrococcus furiosus. We identify putative Na+ binding sites and proton pathways leading across the membrane
and to the NiFe-active center as well as conformational changes that
regulate ion uptake. We suggest that Na+ binding and protonation
changes at a putative ion-binding site couple to proton transfer across
the antiporter-like MbhH subunit by modulating the conformational
state of a conserved ion pair at the subunit interface. Our findings
illustrate conserved coupling principles within the complex I superfamily
and provide functional insight into archaeal energy transduction mechanisms.
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Affiliation(s)
- Max E Mühlbauer
- Department of Biochemistry and Biophysics, Stockholm University, 10691 Stockholm, Sweden.,Department of Chemistry, Technical University of Munich, Lichtenbergstraße 4, 85748 Garching, Germany
| | - Ana P Gamiz-Hernandez
- Department of Biochemistry and Biophysics, Stockholm University, 10691 Stockholm, Sweden
| | - Ville R I Kaila
- Department of Biochemistry and Biophysics, Stockholm University, 10691 Stockholm, Sweden.,Department of Chemistry, Technical University of Munich, Lichtenbergstraße 4, 85748 Garching, Germany
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14
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Parey K, Lasham J, Mills DJ, Djurabekova A, Haapanen O, Yoga EG, Xie H, Kühlbrandt W, Sharma V, Vonck J, Zickermann V. High-resolution structure and dynamics of mitochondrial complex I-Insights into the proton pumping mechanism. SCIENCE ADVANCES 2021; 7:eabj3221. [PMID: 34767441 PMCID: PMC8589321 DOI: 10.1126/sciadv.abj3221] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 09/24/2021] [Indexed: 05/23/2023]
Abstract
Mitochondrial NADH:ubiquinone oxidoreductase (complex I) is a 1-MDa membrane protein complex with a central role in energy metabolism. Redox-driven proton translocation by complex I contributes substantially to the proton motive force that drives ATP synthase. Several structures of complex I from bacteria and mitochondria have been determined, but its catalytic mechanism has remained controversial. We here present the cryo-EM structure of complex I from Yarrowia lipolytica at 2.1-Å resolution, which reveals the positions of more than 1600 protein-bound water molecules, of which ~100 are located in putative proton translocation pathways. Another structure of the same complex under steady-state activity conditions at 3.4-Å resolution indicates conformational transitions that we associate with proton injection into the central hydrophilic axis. By combining high-resolution structural data with site-directed mutagenesis and large-scale molecular dynamic simulations, we define details of the proton translocation pathways and offer insights into the redox-coupled proton pumping mechanism of complex I.
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Affiliation(s)
- Kristian Parey
- Institute of Biochemistry II, University Hospital, Goethe University, 60590 Frankfurt am Main, Germany
- Department of Structural Biology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
- Centre for Biomolecular Magnetic Resonance, Institute for Biophysical Chemistry, Goethe University, 60438 Frankfurt am Main, Germany
| | - Jonathan Lasham
- Department of Physics, University of Helsinki, 00014 Helsinki, Finland
| | - Deryck J. Mills
- Department of Structural Biology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Amina Djurabekova
- Department of Physics, University of Helsinki, 00014 Helsinki, Finland
| | - Outi Haapanen
- Department of Physics, University of Helsinki, 00014 Helsinki, Finland
| | - Etienne Galemou Yoga
- Institute of Biochemistry II, University Hospital, Goethe University, 60590 Frankfurt am Main, Germany
- Centre for Biomolecular Magnetic Resonance, Institute for Biophysical Chemistry, Goethe University, 60438 Frankfurt am Main, Germany
| | - Hao Xie
- Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Werner Kühlbrandt
- Department of Structural Biology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Vivek Sharma
- Department of Physics, University of Helsinki, 00014 Helsinki, Finland
- HiLIFE Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - Janet Vonck
- Department of Structural Biology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Volker Zickermann
- Institute of Biochemistry II, University Hospital, Goethe University, 60590 Frankfurt am Main, Germany
- Centre for Biomolecular Magnetic Resonance, Institute for Biophysical Chemistry, Goethe University, 60438 Frankfurt am Main, Germany
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15
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Al-Attar S, Rendon J, Sidore M, Duneau JP, Seduk F, Biaso F, Grimaldi S, Guigliarelli B, Magalon A. Gating of Substrate Access and Long-Range Proton Transfer in Escherichia coli Nitrate Reductase A: The Essential Role of a Remote Glutamate Residue. ACS Catal 2021. [DOI: 10.1021/acscatal.1c03988] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Sinan Al-Attar
- Laboratoire de Chimie Bactérienne (UMR7283), IMM, IM2B, Aix Marseille Université, CNRS, 13402 Marseille, France
| | - Julia Rendon
- Laboratoire de Bioénergétique et Ingénierie des Protéines (UMR7281), IMM, IM2B, Aix Marseille Université, CNRS, 13402 Marseille, France
| | - Marlon Sidore
- Laboratoire d’Ingénierie des Systèmes Macromoléculaires (UMR7255), IMM, IM2B, Aix Marseille Université, CNRS, 13402 Marseille, France
| | - Jean-Pierre Duneau
- Laboratoire d’Ingénierie des Systèmes Macromoléculaires (UMR7255), IMM, IM2B, Aix Marseille Université, CNRS, 13402 Marseille, France
| | - Farida Seduk
- Laboratoire de Chimie Bactérienne (UMR7283), IMM, IM2B, Aix Marseille Université, CNRS, 13402 Marseille, France
| | - Frédéric Biaso
- Laboratoire de Bioénergétique et Ingénierie des Protéines (UMR7281), IMM, IM2B, Aix Marseille Université, CNRS, 13402 Marseille, France
| | - Stéphane Grimaldi
- Laboratoire de Bioénergétique et Ingénierie des Protéines (UMR7281), IMM, IM2B, Aix Marseille Université, CNRS, 13402 Marseille, France
| | - Bruno Guigliarelli
- Laboratoire de Bioénergétique et Ingénierie des Protéines (UMR7281), IMM, IM2B, Aix Marseille Université, CNRS, 13402 Marseille, France
| | - Axel Magalon
- Laboratoire de Chimie Bactérienne (UMR7283), IMM, IM2B, Aix Marseille Université, CNRS, 13402 Marseille, France
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16
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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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17
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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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18
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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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19
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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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20
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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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21
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Bruhn H, Samuelsson K, Schober FA, Engvall M, Lesko N, Wibom R, Nennesmo I, Calvo-Garrido J, Press R, Stranneheim H, Freyer C, Wedell A, Wredenberg A. Novel Mutation m.10372A>G in MT-ND3 Causing Sensorimotor Axonal Polyneuropathy. NEUROLOGY-GENETICS 2021; 7:e566. [PMID: 33732874 PMCID: PMC7962437 DOI: 10.1212/nxg.0000000000000566] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 01/12/2021] [Indexed: 11/15/2022]
Abstract
Objective To investigate the pathogenicity of a novel MT-ND3 mutation identified in a patient with adult-onset sensorimotor axonal polyneuropathy and report the clinical, morphologic, and biochemical findings. Methods Clinical assessments and morphologic and biochemical investigations of skeletal muscle and cultured myoblasts from the patient were performed. Whole-genome sequencing (WGS) of DNA from skeletal muscle and Sanger sequencing of mitochondrial DNA (mtDNA) from both skeletal muscle and cultured myoblasts were performed. Heteroplasmic levels of mutated mtDNA in different tissues were quantified by last-cycle hot PCR. Results Muscle showed ragged red fibers, paracrystalline inclusions, a significant reduction in complex I (CI) respiratory chain (RC) activity, and decreased adenosine triphosphate (ATP) production for all substrates used by CI. Sanger sequencing of DNA from skeletal muscle detected a unique previously unreported heteroplasmic mutation in mtDNA encoded MT-ND3, coding for a subunit in CI. WGS confirmed the mtDNA mutation but did not detect any other mutation explaining the disease. Cultured myoblasts, however, did not carry the mutation, and RC activity measurements in myoblasts were normal. Conclusions We report a case with adult-onset sensorimotor axonal polyneuropathy caused by a novel mtDNA mutation in MT-ND3. Loss of heteroplasmy in blood, cultured fibroblasts and myoblasts from the patient, and normal measurement of RC activity of the myoblasts support pathogenicity of the mutation. These findings highlight the importance of mitochondrial investigations in patients presenting with seemingly idiopathic polyneuropathy, especially if muscle also is affected.
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Affiliation(s)
- Helene Bruhn
- Department of Medical Biochemistry and Biophysics (H.B., R.W., C.F., A. Wredenberg), Karolinska Institutet; Centre for Inherited Metabolic Diseases (H.B., R.W., C.F., M.E., N.L., H.S., A. Wedell, A. Wredenberg), Karolinska University Hospital; Department of Clinical Neuroscience (K.S., R.P.), Karolinska Institutet; Department of Neurology (K.S., R.P.), Karolinska University Hospital; Department of Molecular Medicine and Surgery (F.A.S., M.E., N.L., J.C.-G., H.S., A. Wedell), Karolinska Institutet; Department of Pathology (I.N.), Karolinska University Hospital; and Science for Life Laboratory (H.S.), Karolinska Institutet, Stockholm, Sweden
| | - Kristin Samuelsson
- Department of Medical Biochemistry and Biophysics (H.B., R.W., C.F., A. Wredenberg), Karolinska Institutet; Centre for Inherited Metabolic Diseases (H.B., R.W., C.F., M.E., N.L., H.S., A. Wedell, A. Wredenberg), Karolinska University Hospital; Department of Clinical Neuroscience (K.S., R.P.), Karolinska Institutet; Department of Neurology (K.S., R.P.), Karolinska University Hospital; Department of Molecular Medicine and Surgery (F.A.S., M.E., N.L., J.C.-G., H.S., A. Wedell), Karolinska Institutet; Department of Pathology (I.N.), Karolinska University Hospital; and Science for Life Laboratory (H.S.), Karolinska Institutet, Stockholm, Sweden
| | - Florian A Schober
- Department of Medical Biochemistry and Biophysics (H.B., R.W., C.F., A. Wredenberg), Karolinska Institutet; Centre for Inherited Metabolic Diseases (H.B., R.W., C.F., M.E., N.L., H.S., A. Wedell, A. Wredenberg), Karolinska University Hospital; Department of Clinical Neuroscience (K.S., R.P.), Karolinska Institutet; Department of Neurology (K.S., R.P.), Karolinska University Hospital; Department of Molecular Medicine and Surgery (F.A.S., M.E., N.L., J.C.-G., H.S., A. Wedell), Karolinska Institutet; Department of Pathology (I.N.), Karolinska University Hospital; and Science for Life Laboratory (H.S.), Karolinska Institutet, Stockholm, Sweden
| | - Martin Engvall
- Department of Medical Biochemistry and Biophysics (H.B., R.W., C.F., A. Wredenberg), Karolinska Institutet; Centre for Inherited Metabolic Diseases (H.B., R.W., C.F., M.E., N.L., H.S., A. Wedell, A. Wredenberg), Karolinska University Hospital; Department of Clinical Neuroscience (K.S., R.P.), Karolinska Institutet; Department of Neurology (K.S., R.P.), Karolinska University Hospital; Department of Molecular Medicine and Surgery (F.A.S., M.E., N.L., J.C.-G., H.S., A. Wedell), Karolinska Institutet; Department of Pathology (I.N.), Karolinska University Hospital; and Science for Life Laboratory (H.S.), Karolinska Institutet, Stockholm, Sweden
| | - Nicole Lesko
- Department of Medical Biochemistry and Biophysics (H.B., R.W., C.F., A. Wredenberg), Karolinska Institutet; Centre for Inherited Metabolic Diseases (H.B., R.W., C.F., M.E., N.L., H.S., A. Wedell, A. Wredenberg), Karolinska University Hospital; Department of Clinical Neuroscience (K.S., R.P.), Karolinska Institutet; Department of Neurology (K.S., R.P.), Karolinska University Hospital; Department of Molecular Medicine and Surgery (F.A.S., M.E., N.L., J.C.-G., H.S., A. Wedell), Karolinska Institutet; Department of Pathology (I.N.), Karolinska University Hospital; and Science for Life Laboratory (H.S.), Karolinska Institutet, Stockholm, Sweden
| | - Rolf Wibom
- Department of Medical Biochemistry and Biophysics (H.B., R.W., C.F., A. Wredenberg), Karolinska Institutet; Centre for Inherited Metabolic Diseases (H.B., R.W., C.F., M.E., N.L., H.S., A. Wedell, A. Wredenberg), Karolinska University Hospital; Department of Clinical Neuroscience (K.S., R.P.), Karolinska Institutet; Department of Neurology (K.S., R.P.), Karolinska University Hospital; Department of Molecular Medicine and Surgery (F.A.S., M.E., N.L., J.C.-G., H.S., A. Wedell), Karolinska Institutet; Department of Pathology (I.N.), Karolinska University Hospital; and Science for Life Laboratory (H.S.), Karolinska Institutet, Stockholm, Sweden
| | - Inger Nennesmo
- Department of Medical Biochemistry and Biophysics (H.B., R.W., C.F., A. Wredenberg), Karolinska Institutet; Centre for Inherited Metabolic Diseases (H.B., R.W., C.F., M.E., N.L., H.S., A. Wedell, A. Wredenberg), Karolinska University Hospital; Department of Clinical Neuroscience (K.S., R.P.), Karolinska Institutet; Department of Neurology (K.S., R.P.), Karolinska University Hospital; Department of Molecular Medicine and Surgery (F.A.S., M.E., N.L., J.C.-G., H.S., A. Wedell), Karolinska Institutet; Department of Pathology (I.N.), Karolinska University Hospital; and Science for Life Laboratory (H.S.), Karolinska Institutet, Stockholm, Sweden
| | - Javier Calvo-Garrido
- Department of Medical Biochemistry and Biophysics (H.B., R.W., C.F., A. Wredenberg), Karolinska Institutet; Centre for Inherited Metabolic Diseases (H.B., R.W., C.F., M.E., N.L., H.S., A. Wedell, A. Wredenberg), Karolinska University Hospital; Department of Clinical Neuroscience (K.S., R.P.), Karolinska Institutet; Department of Neurology (K.S., R.P.), Karolinska University Hospital; Department of Molecular Medicine and Surgery (F.A.S., M.E., N.L., J.C.-G., H.S., A. Wedell), Karolinska Institutet; Department of Pathology (I.N.), Karolinska University Hospital; and Science for Life Laboratory (H.S.), Karolinska Institutet, Stockholm, Sweden
| | - Rayomand Press
- Department of Medical Biochemistry and Biophysics (H.B., R.W., C.F., A. Wredenberg), Karolinska Institutet; Centre for Inherited Metabolic Diseases (H.B., R.W., C.F., M.E., N.L., H.S., A. Wedell, A. Wredenberg), Karolinska University Hospital; Department of Clinical Neuroscience (K.S., R.P.), Karolinska Institutet; Department of Neurology (K.S., R.P.), Karolinska University Hospital; Department of Molecular Medicine and Surgery (F.A.S., M.E., N.L., J.C.-G., H.S., A. Wedell), Karolinska Institutet; Department of Pathology (I.N.), Karolinska University Hospital; and Science for Life Laboratory (H.S.), Karolinska Institutet, Stockholm, Sweden
| | - Henrik Stranneheim
- Department of Medical Biochemistry and Biophysics (H.B., R.W., C.F., A. Wredenberg), Karolinska Institutet; Centre for Inherited Metabolic Diseases (H.B., R.W., C.F., M.E., N.L., H.S., A. Wedell, A. Wredenberg), Karolinska University Hospital; Department of Clinical Neuroscience (K.S., R.P.), Karolinska Institutet; Department of Neurology (K.S., R.P.), Karolinska University Hospital; Department of Molecular Medicine and Surgery (F.A.S., M.E., N.L., J.C.-G., H.S., A. Wedell), Karolinska Institutet; Department of Pathology (I.N.), Karolinska University Hospital; and Science for Life Laboratory (H.S.), Karolinska Institutet, Stockholm, Sweden
| | - Christoph Freyer
- Department of Medical Biochemistry and Biophysics (H.B., R.W., C.F., A. Wredenberg), Karolinska Institutet; Centre for Inherited Metabolic Diseases (H.B., R.W., C.F., M.E., N.L., H.S., A. Wedell, A. Wredenberg), Karolinska University Hospital; Department of Clinical Neuroscience (K.S., R.P.), Karolinska Institutet; Department of Neurology (K.S., R.P.), Karolinska University Hospital; Department of Molecular Medicine and Surgery (F.A.S., M.E., N.L., J.C.-G., H.S., A. Wedell), Karolinska Institutet; Department of Pathology (I.N.), Karolinska University Hospital; and Science for Life Laboratory (H.S.), Karolinska Institutet, Stockholm, Sweden
| | - Anna Wedell
- Department of Medical Biochemistry and Biophysics (H.B., R.W., C.F., A. Wredenberg), Karolinska Institutet; Centre for Inherited Metabolic Diseases (H.B., R.W., C.F., M.E., N.L., H.S., A. Wedell, A. Wredenberg), Karolinska University Hospital; Department of Clinical Neuroscience (K.S., R.P.), Karolinska Institutet; Department of Neurology (K.S., R.P.), Karolinska University Hospital; Department of Molecular Medicine and Surgery (F.A.S., M.E., N.L., J.C.-G., H.S., A. Wedell), Karolinska Institutet; Department of Pathology (I.N.), Karolinska University Hospital; and Science for Life Laboratory (H.S.), Karolinska Institutet, Stockholm, Sweden
| | - Anna Wredenberg
- Department of Medical Biochemistry and Biophysics (H.B., R.W., C.F., A. Wredenberg), Karolinska Institutet; Centre for Inherited Metabolic Diseases (H.B., R.W., C.F., M.E., N.L., H.S., A. Wedell, A. Wredenberg), Karolinska University Hospital; Department of Clinical Neuroscience (K.S., R.P.), Karolinska Institutet; Department of Neurology (K.S., R.P.), Karolinska University Hospital; Department of Molecular Medicine and Surgery (F.A.S., M.E., N.L., J.C.-G., H.S., A. Wedell), Karolinska Institutet; Department of Pathology (I.N.), Karolinska University Hospital; and Science for Life Laboratory (H.S.), Karolinska Institutet, Stockholm, Sweden
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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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23
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A conserved arginine residue is critical for stabilizing the N2 FeS cluster in mitochondrial complex I. J Biol Chem 2021; 296:100474. [PMID: 33640456 PMCID: PMC8042128 DOI: 10.1016/j.jbc.2021.100474] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 02/18/2021] [Accepted: 02/24/2021] [Indexed: 11/22/2022] Open
Abstract
Respiratory complex I (NADH:ubiquinone oxidoreductase), the first enzyme of the electron-transport chain, captures the free energy released by NADH oxidation and ubiquinone reduction to translocate protons across an energy-transducing membrane and drive ATP synthesis during oxidative phosphorylation. The cofactor that transfers the electrons directly to ubiquinone is an iron–sulfur cluster (N2) located in the NDUFS2/NUCM subunit. A nearby arginine residue (R121), which forms part of the second coordination sphere of the N2 cluster, is known to be posttranslationally dimethylated but its functional and structural significance are not known. Here, we show that mutations of this arginine residue (R121M/K) abolish the quinone-reductase activity, concomitant with disappearance of the N2 signature from the electron paramagnetic resonance (EPR) spectrum. Analysis of the cryo-EM structure of NDUFS2-R121M complex I at 3.7 Å resolution identified the absence of the cubane N2 cluster as the cause of the dysfunction, within an otherwise intact enzyme. The mutation further induced localized disorder in nearby elements of the quinone-binding site, consistent with the close connections between the cluster and substrate-binding regions. Our results demonstrate that R121 is required for the formation and/or stability of the N2 cluster and highlight the importance of structural analyses for mechanistic interpretation of biochemical and spectroscopic data on complex I variants.
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24
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Destiarani W, Mulyani R, Yusuf M, Maksum IP. Molecular Dynamics Simulation of T10609C and C10676G Mutations of Mitochondrial ND4L Gene Associated With Proton Translocation in Type 2 Diabetes Mellitus and Cataract Patients. Bioinform Biol Insights 2020; 14:1177932220978672. [PMID: 33402819 PMCID: PMC7747115 DOI: 10.1177/1177932220978672] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Accepted: 11/14/2020] [Indexed: 11/17/2022] Open
Abstract
The mutation rate of mitochondrial DNA (mtDNA) is 17 times higher than nuclear DNA, and these mutations can cause mitochondrial disease in 1 of 10.000 people. The T10609C mutation was identified in type 2 diabetes mellitus (T2DM) patients and the C10676G mutation in cataract patients, with both mutations occurring in the ND4L gene of mtDNA that encodes ND4L protein. ND4L protein, a subunit of complex I in the respiratory complex, has been shown to play a role in the proton translocation process. The purpose of this study was to investigate the effect of both mutations on the proton translocation mechanism. Mutation mapping showed changes in amino acids M47T (T10609C) and C69W (C10676G). The 100 ns molecular dynamics (MD) simulations performed on native and mutants of ND4L-ND6 subunits. It is revealed that the native model had a similar proton translocation pathway to that of complex I from other organisms. Interestingly, the mutant M47T and C69W showed the interruption of the translocation pathway by a hydrogen bond formation between Glu34 and Tyr157. It is observed that the mutations were restricting the passage of water molecules through the transmembrane region. These results could help to develop the computational assay for the validation of a specific genetic biomarker for T2DM and cataracts.
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Affiliation(s)
- Wanda Destiarani
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Sumedang, Indonesia
| | - Rahmaniar Mulyani
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Sumedang, Indonesia
| | - Muhammad Yusuf
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Sumedang, Indonesia.,Research Center for Molecular Biotechnology and Bioinformatics, Universitas Padjadjaran, Bandung, Indonesia
| | - Iman Permana Maksum
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Sumedang, Indonesia
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25
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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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26
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Essential role of accessory subunit LYRM6 in the mechanism of mitochondrial complex I. Nat Commun 2020; 11:6008. [PMID: 33243981 PMCID: PMC7693276 DOI: 10.1038/s41467-020-19778-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 10/29/2020] [Indexed: 01/18/2023] Open
Abstract
Respiratory complex I catalyzes electron transfer from NADH to ubiquinone (Q) coupled to vectorial proton translocation across the inner mitochondrial membrane. Despite recent progress in structure determination of this very large membrane protein complex, the coupling mechanism is a matter of ongoing debate and the function of accessory subunits surrounding the canonical core subunits is essentially unknown. Concerted rearrangements within a cluster of conserved loops of central subunits NDUFS2 (β1-β2S2 loop), ND1 (TMH5-6ND1 loop) and ND3 (TMH1-2ND3 loop) were suggested to be critical for its proton pumping mechanism. Here, we show that stabilization of the TMH1-2ND3 loop by accessory subunit LYRM6 (NDUFA6) is pivotal for energy conversion by mitochondrial complex I. We determined the high-resolution structure of inactive mutant F89ALYRM6 of eukaryotic complex I from the yeast Yarrowia lipolytica and found long-range structural changes affecting the entire loop cluster. In atomistic molecular dynamics simulations of the mutant, we observed conformational transitions in the loop cluster that disrupted a putative pathway for delivery of substrate protons required in Q redox chemistry. Our results elucidate in detail the essential role of accessory subunit LYRM6 for the function of eukaryotic complex I and offer clues on its redox-linked proton pumping mechanism. Respiratory complex I plays a key role in energy metabolism. Cryo-EM structure of a mutant accessory subunit LYRM6 from the yeast Yarrowia lipolytica and molecular dynamics simulations reveal conformational changes at the interface between LYRM6 and subunit ND3, propagated further into the complex. These findings offer insight into the mechanism of proton pumping by respiratory complex I.
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27
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Grba DN, Hirst J. Mitochondrial complex I structure reveals ordered water molecules for catalysis and proton translocation. Nat Struct Mol Biol 2020; 27:892-900. [PMID: 32747785 PMCID: PMC7612091 DOI: 10.1038/s41594-020-0473-x] [Citation(s) in RCA: 76] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 06/26/2020] [Indexed: 01/09/2023]
Abstract
Mitochondrial complex I powers ATP synthesis by oxidative phosphorylation, exploiting the energy from ubiquinone reduction by NADH to drive protons across the energy-transducing inner membrane. Recent cryo-EM analyses of mammalian and yeast complex I have revolutionized structural and mechanistic knowledge and defined structures in different functional states. Here, we describe a 2.7-Å-resolution structure of the 42-subunit complex I from the yeast Yarrowia lipolytica containing 275 structured water molecules. We identify a proton-relay pathway for ubiquinone reduction and water molecules that connect mechanistically crucial elements and constitute proton-translocation pathways through the membrane. By comparison with known structures, we deconvolute structural changes governing the mammalian 'deactive transition' (relevant to ischemia-reperfusion injury) and their effects on the ubiquinone-binding site and a connected cavity in ND1. Our structure thus provides important insights into catalysis by this enigmatic respiratory machine.
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Affiliation(s)
- Daniel N Grba
- The Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Judy Hirst
- The Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK.
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28
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29
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Kampjut D, Sazanov LA. The coupling mechanism of mammalian respiratory complex I. Science 2020; 370:science.abc4209. [PMID: 32972993 DOI: 10.1126/science.abc4209] [Citation(s) in RCA: 129] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 09/08/2020] [Indexed: 12/16/2022]
Abstract
Mitochondrial complex I couples NADH:ubiquinone oxidoreduction to proton pumping by an unknown mechanism. Here, we present cryo-electron microscopy structures of ovine complex I in five different conditions, including turnover, at resolutions up to 2.3 to 2.5 angstroms. Resolved water molecules allowed us to experimentally define the proton translocation pathways. Quinone binds at three positions along the quinone cavity, as does the inhibitor rotenone that also binds within subunit ND4. Dramatic conformational changes around the quinone cavity couple the redox reaction to proton translocation during open-to-closed state transitions of the enzyme. In the induced deactive state, the open conformation is arrested by the ND6 subunit. We propose a detailed molecular coupling mechanism of complex I, which is an unexpected combination of conformational changes and electrostatic interactions.
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Affiliation(s)
- Domen Kampjut
- IST Austria, Am Campus 1, 3400 Klosterneuburg, Austria
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30
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Gutiérrez-Fernández J, Kaszuba K, Minhas GS, Baradaran R, Tambalo M, Gallagher DT, Sazanov LA. Key role of quinone in the mechanism of respiratory complex I. Nat Commun 2020; 11:4135. [PMID: 32811817 PMCID: PMC7434922 DOI: 10.1038/s41467-020-17957-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 07/28/2020] [Indexed: 01/12/2023] Open
Abstract
Complex I is the first and the largest enzyme of respiratory chains in bacteria and mitochondria. The mechanism which couples spatially separated transfer of electrons to proton translocation in complex I is not known. Here we report five crystal structures of T. thermophilus enzyme in complex with NADH or quinone-like compounds. We also determined cryo-EM structures of major and minor native states of the complex, differing in the position of the peripheral arm. Crystal structures show that binding of quinone-like compounds (but not of NADH) leads to a related global conformational change, accompanied by local re-arrangements propagating from the quinone site to the nearest proton channel. Normal mode and molecular dynamics analyses indicate that these are likely to represent the first steps in the proton translocation mechanism. Our results suggest that quinone binding and chemistry play a key role in the coupling mechanism of complex I. Complex I (NADH:ubiquinone oxidoreductase) is the first enzyme of the respiratory chain in bacteria and mitochondria. Here, the authors present cryo-EM and crystal structures of T. thermophilus complex I in different conformational states and further analyse them by Normal Mode Analysis and molecular dynamics simulations and conclude that quinone redox reactions are important for the coupling mechanism of complex I.
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Affiliation(s)
| | - Karol Kaszuba
- Institute of Science and Technology Austria, Am Campus 1, A-3400, Klosterneuburg, Austria
| | - Gurdeep S Minhas
- Medical Research Council Mitochondrial Biology Unit, Keith Peters Building, Hills rd, Cambridge, CB2 0XY, UK.,Sosei Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Rozbeh Baradaran
- Medical Research Council Mitochondrial Biology Unit, Keith Peters Building, Hills rd, Cambridge, CB2 0XY, UK.,Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 17165, Solna, Sweden
| | - Margherita Tambalo
- Institute of Science and Technology Austria, Am Campus 1, A-3400, Klosterneuburg, Austria
| | - David T Gallagher
- Medical Research Council Mitochondrial Biology Unit, Keith Peters Building, Hills rd, Cambridge, CB2 0XY, UK
| | - Leonid A Sazanov
- Institute of Science and Technology Austria, Am Campus 1, A-3400, Klosterneuburg, Austria.
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31
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Haapanen O, Reidelbach M, Sharma V. Coupling of quinone dynamics to proton pumping in respiratory complex I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148287. [PMID: 32777307 DOI: 10.1016/j.bbabio.2020.148287] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 07/09/2020] [Accepted: 08/03/2020] [Indexed: 12/12/2022]
Abstract
Respiratory complex I (NADH:quinone oxidoreductase) plays a central role in generating the proton electrochemical gradient in mitochondrial and bacterial membranes, which is needed to generate ATP. Several high-resolution structures of complex I have been determined, revealing its intricate architecture and complementing the biochemical and biophysical studies. However, the molecular mechanism of long-range coupling between ubiquinone (Q) reduction and proton pumping is not known. Computer simulations have been applied to decipher the dynamics of Q molecule in the ~30 Å long Q tunnel. In this short report, we discuss the binding and dynamics of Q at computationally predicted Q binding sites, many of which are supported by structural data on complex I. We suggest that the binding of Q at these sites is coupled to proton pumping by means of conformational rearrangements in the conserved loops of core subunits.
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Affiliation(s)
- Outi Haapanen
- Department of Physics, University of Helsinki, Finland
| | | | - Vivek Sharma
- Department of Physics, University of Helsinki, Finland; HiLIFE Institute of Biotechnology, University of Helsinki, Finland.
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32
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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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33
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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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34
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Djurabekova A, Haapanen O, Sharma V. Proton motive function of the terminal antiporter-like subunit in respiratory complex I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148185. [PMID: 32171794 DOI: 10.1016/j.bbabio.2020.148185] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 01/15/2020] [Accepted: 03/09/2020] [Indexed: 12/20/2022]
Abstract
In the aerobic respiratory chains of many organisms, complex I functions as the first electron input. By reducing ubiquinone (Q) to ubiquinol, it catalyzes the translocation of protons across the membrane as far as ~200 Å from the site of redox reactions. Despite significant amount of structural and biochemical data, the details of redox coupled proton pumping in complex I are poorly understood. In particular, the proton transfer pathways are extremely difficult to characterize with the current structural and biochemical techniques. Here, we applied multiscale computational approaches to identify the proton transfer paths in the terminal antiporter-like subunit of complex I. Data from combined classical and quantum chemical simulations reveal for the first time structural elements that are exclusive to the subunit, and enables the enzyme to achieve coupling between the spatially separated Q redox reactions and proton pumping. By studying long time scale protonation and hydration dependent conformational dynamics of key amino acid residues, we provide novel insights into the proton pumping mechanism 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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35
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Parey K, Wirth C, Vonck J, Zickermann V. Respiratory complex I - structure, mechanism and evolution. Curr Opin Struct Biol 2020; 63:1-9. [PMID: 32058886 DOI: 10.1016/j.sbi.2020.01.004] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 01/10/2020] [Indexed: 02/07/2023]
Abstract
Respiratory complex I is an intricate multi-subunit membrane protein with a central function in aerobic energy metabolism. During the last years, structures of mitochondrial complex I and respiratory supercomplexes were determined by cryo-EM at increasing resolution. Structural and computational studies have shed light on the dynamics of proton translocation pathways, the interaction of complex I with lipids and the unusual access pathway of ubiquinone to the active site. Recent advances in understanding complex I function include characterization of specific conformational changes that are critical for proton pumping. Cryo-EM structures of the NADH dehydrogenase-like (NDH) complex of photosynthesis and a bacterial membrane bound hydrogenase (MBH) have provided a broader perspective on the complex I superfamily.
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Affiliation(s)
- Kristian Parey
- Institute of Biochemistry II, University Hospital, Goethe University, Frankfurt am Main, Germany; Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany; Centre for Biomolecular Magnetic Resonance, Institute for Biophysical Chemistry, Goethe University, Frankfurt am Main, Germany
| | - Christophe Wirth
- Institute of Biochemistry and Molecular Biology, ZBMZ, Medical Faculty, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Janet Vonck
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
| | - 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.
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36
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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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37
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Mutations in a conserved loop in the PSST subunit of respiratory complex I affect ubiquinone binding and dynamics. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1860:573-581. [PMID: 31226318 DOI: 10.1016/j.bbabio.2019.06.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 05/10/2019] [Accepted: 06/15/2019] [Indexed: 12/13/2022]
Abstract
Respiratory complex I catalyses the reduction of ubiquinone (Q) from NADH coupled to proton pumping across the inner membrane of mitochondria. The electrical charging of the inner mitochondrial membrane drives the synthesis of ATP, which is used to power biochemical reactions of the cell. The recent surge in structural data on complex I from bacteria and mitochondria have contributed to significant understanding of its molecular architecture. However, despite these accomplishments, the role of various subdomains in redox-coupled proton pumping remains entirely unclear. In this work, we have mutated conserved residues in the loop of the PSST subunit that faces the ~30 Å long unique Q-binding tunnel of respiratory complex I. The data show a drastic decrease in Q reductase activity upon mutating several residues despite full assembly of the complex. In-silico modeling and multiple microsecond long molecular dynamics simulations of wild-type and enzyme variants with exchanges of conserved arginine residues revealed remarkable ejection of the bound Q from the site near terminal electron donor N2. Based on experiments and long-time scale molecular simulations, we identify microscopic elements that dynamically control the diffusion of Q and are central to redox-coupled proton pumping in respiratory complex I.
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38
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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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Enkavi G, Javanainen M, Kulig W, Róg T, Vattulainen I. Multiscale Simulations of Biological Membranes: The Challenge To Understand Biological Phenomena in a Living Substance. Chem Rev 2019; 119:5607-5774. [PMID: 30859819 PMCID: PMC6727218 DOI: 10.1021/acs.chemrev.8b00538] [Citation(s) in RCA: 173] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
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Biological
membranes are tricky to investigate. They are complex
in terms of molecular composition and structure, functional
over a wide range of time scales, and characterized
by nonequilibrium conditions. Because of all of these
features, simulations are a great technique to study biomembrane
behavior. A significant part of the functional processes
in biological membranes takes place at the molecular
level; thus computer simulations are the method of
choice to explore how their properties emerge from specific
molecular features and how the interplay among the numerous
molecules gives rise to function over spatial and
time scales larger than the molecular ones. In this
review, we focus on this broad theme. We discuss the current
state-of-the-art of biomembrane simulations that, until
now, have largely focused on a rather narrow picture
of the complexity of the membranes. Given this, we
also discuss the challenges that we should unravel in the
foreseeable future. Numerous features such as the actin-cytoskeleton
network, the glycocalyx network, and nonequilibrium
transport under ATP-driven conditions have so far
received very little attention; however, the potential
of simulations to solve them would be exceptionally high. A
major milestone for this research would be that one day
we could say that computer simulations genuinely research
biological membranes, not just lipid bilayers.
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Affiliation(s)
- Giray Enkavi
- Department of Physics , University of Helsinki , P.O. Box 64, FI-00014 Helsinki , Finland
| | - Matti Javanainen
- Department of Physics , University of Helsinki , P.O. Box 64, FI-00014 Helsinki , Finland.,Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences , Flemingovo naḿesti 542/2 , 16610 Prague , Czech Republic.,Computational Physics Laboratory , Tampere University , P.O. Box 692, FI-33014 Tampere , Finland
| | - Waldemar Kulig
- Department of Physics , University of Helsinki , P.O. Box 64, FI-00014 Helsinki , Finland
| | - Tomasz Róg
- Department of Physics , University of Helsinki , P.O. Box 64, FI-00014 Helsinki , Finland.,Computational Physics Laboratory , Tampere University , P.O. Box 692, FI-33014 Tampere , Finland
| | - Ilpo Vattulainen
- Department of Physics , University of Helsinki , P.O. Box 64, FI-00014 Helsinki , Finland.,Computational Physics Laboratory , Tampere University , P.O. Box 692, FI-33014 Tampere , Finland.,MEMPHYS-Center for Biomembrane Physics
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40
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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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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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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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