151
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Reda T, Barker CD, Hirst J. Reduction of the iron-sulfur clusters in mitochondrial NADH:ubiquinone oxidoreductase (complex I) by EuII-DTPA, a very low potential reductant. Biochemistry 2008; 47:8885-93. [PMID: 18651753 DOI: 10.1021/bi800437g] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
NADH:ubiquinone oxidoreductase (complex I) is the first enzyme of the mitochondrial electron transport chain. It contains a flavin mononucleotide to oxidize NADH, and eight iron-sulfur clusters. Seven of them transfer electrons between the flavin and the quinone-binding site, and one is on the opposite side of the flavin. Although most information about their properties is from EPR, the spectra from only five clusters have been observed, and it is difficult to match them to the structurally defined clusters. Here, we analyze complex I from bovine mitochondria reacted with a very low potential reductant, to impose a potential approaching -1 V. We compare the spectra with those from higher potentials and from the 24 kDa subunit and flavoprotein subcomplex, and model the spectra by starting from those with fewer components and building the complexity gradually. Spectrum N1a, from the 24 kDa subunit [2Fe-2S] cluster, is not observed in bovine complex I at any potential. Spectrum N1b, from the 75 kDa subunit [2Fe-2S] cluster, exhibits a lower potential than the N3, N4 and N5 spectra of three [4Fe-4S] clusters. In the lowest potential spectra an N5-type spectrum is observed at unusually high temperature (indicating a significant change to the cluster, or that two clusters have very similar g values), the relaxation rate of N1b increases (indicating that a nearby cluster has become reduced) and a new feature with an apparent g value of 2.16 suggests an interaction between two reduced clusters. The consequences of these observations for electron transfer in complex I are discussed.
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Affiliation(s)
- Torsten Reda
- Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY, UK
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152
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Hurd TR, Requejo R, Filipovska A, Brown S, Prime TA, Robinson AJ, Fearnley IM, Murphy MP. Complex I within oxidatively stressed bovine heart mitochondria is glutathionylated on Cys-531 and Cys-704 of the 75-kDa subunit: potential role of CYS residues in decreasing oxidative damage. J Biol Chem 2008; 283:24801-15. [PMID: 18611857 PMCID: PMC2529008 DOI: 10.1074/jbc.m803432200] [Citation(s) in RCA: 155] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Complex I has reactive thiols on its surface that interact with the
mitochondrial glutathione pool and are implicated in oxidative damage in many
pathologies. However, the Cys residues and the thiol modifications involved
are not known. Here we investigate complex I thiol modification within
oxidatively stressed mammalian mitochondria, containing physiological levels
of glutathione and glutaredoxin 2. In mitochondria incubated with the thiol
oxidant diamide, complex I is only glutathionylated on the 75-kDa subunit. Of
the 17 Cys residues on the 75-kDa subunit, 6 are not involved in iron-sulfur
centers, making them plausible candidates for glutathionylation. Mass
spectrometry of complex I from oxidatively stressed bovine heart mitochondria
showed that only Cys-531 and Cys-704 were glutathionylated. The other four
non-iron-sulfur center Cys residues remained as free thiols. Complex I
glutathionylation also occurred in response to relatively mild oxidative
stress caused by increased superoxide production from the respiratory chain.
Although complex I glutathionylation within oxidatively stressed mitochondria
correlated with loss of activity, it did not increase superoxide formation,
and reversal of glutathionylation did not restore complex I activity.
Comparison with the known structure of the 75-kDa ortholog Nqo3 from
Thermus thermophilus complex I suggested that Cys-531 and Cys-704 are
on the surface of mammalian complex I, exposed to the mitochondrial
glutathione pool. These findings suggest that Cys-531 and Cys-704 may be
important in preventing oxidative damage to complex I by reacting with free
radicals and other damaging species, with subsequent glutathionylation
recycling the thiyl radicals and sulfenic acids formed on the Cys residues
back to free thiols.
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Affiliation(s)
- Thomas R Hurd
- Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 0XY, United Kingdom
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153
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Léger C, Bertrand P. Direct Electrochemistry of Redox Enzymes as a Tool for Mechanistic Studies. Chem Rev 2008; 108:2379-438. [DOI: 10.1021/cr0680742] [Citation(s) in RCA: 594] [Impact Index Per Article: 37.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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154
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Vinogradov AD. NADH/NAD+ interaction with NADH: ubiquinone oxidoreductase (complex I). BIOCHIMICA ET BIOPHYSICA ACTA 2008; 1777:729-34. [PMID: 18471432 PMCID: PMC2494570 DOI: 10.1016/j.bbabio.2008.04.014] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2008] [Revised: 03/20/2008] [Accepted: 04/13/2008] [Indexed: 10/22/2022]
Abstract
The quantitative data on the binding affinity of NADH, NAD(+), and their analogues for complex I as emerged from the steady-state kinetics data and from more direct studies under equilibrium conditions are summarized and discussed. The redox-dependency of the nucleotide binding and the reductant-induced change of FMN affinity to its tight non-covalent binding site indicate that binding (dissociation) of the substrate (product) may energetically contribute to the proton-translocating activity of complex I.
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Affiliation(s)
- Andrei D Vinogradov
- Department of Biochemistry, School of Biology, Moscow State University, Moscow 119992, Russian Federation.
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155
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Eukaryotic complex I: functional diversity and experimental systems to unravel the assembly process. Mol Genet Genomics 2008; 280:93-110. [DOI: 10.1007/s00438-008-0350-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2008] [Accepted: 05/01/2008] [Indexed: 10/21/2022]
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156
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Generation of Reactive Oxygen Species by Mitochondrial Complex I: Implications in Neurodegeneration. Neurochem Res 2008; 33:2487-501. [DOI: 10.1007/s11064-008-9747-0] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2008] [Accepted: 05/09/2008] [Indexed: 12/21/2022]
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157
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Lill R, Mühlenhoff U. Maturation of Iron-Sulfur Proteins in Eukaryotes: Mechanisms, Connected Processes, and Diseases. Annu Rev Biochem 2008; 77:669-700. [DOI: 10.1146/annurev.biochem.76.052705.162653] [Citation(s) in RCA: 485] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Roland Lill
- Institut für Zytobiologie, Philipps Universität Marburg, Marburg D-35033, Germany;
| | - Ulrich Mühlenhoff
- Institut für Zytobiologie, Philipps Universität Marburg, Marburg D-35033, Germany;
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158
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Lazarou M, Thorburn DR, Ryan MT, McKenzie M. Assembly of mitochondrial complex I and defects in disease. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1793:78-88. [PMID: 18501715 DOI: 10.1016/j.bbamcr.2008.04.015] [Citation(s) in RCA: 139] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2008] [Revised: 04/15/2008] [Accepted: 04/25/2008] [Indexed: 12/19/2022]
Abstract
Isolated complex I deficiency is the most common cause of respiratory chain dysfunction. Defects in human complex I result in energy generation disorders and they are also implicated in neurodegenerative disease and altered apoptotic signaling. Complex I dysfunction often occurs as a result of its impaired assembly. The assembly process of complex I is poorly understood, complicated by the fact that in mammals, it is composed of 45 different subunits and is regulated by both nuclear and mitochondrial genomes. However, in recent years we have gained new insights into complex I biogenesis and a number of assembly factors involved in this process have also been identified. In most cases, these factors have been discovered through their gene mutations that lead to specific complex I defects and result in mitochondrial disease. Here we review how complex I is assembled and the factors required to mediate this process.
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Affiliation(s)
- Michael Lazarou
- Department of Biochemistry, La Trobe University, 3086 Melbourne, Australia
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159
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Ohnishi T, Nakamaru-Ogiso E. Were there any "misassignments" among iron-sulfur clusters N4, N5 and N6b in NADH-quinone oxidoreductase (complex I)? BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:703-10. [PMID: 18486592 DOI: 10.1016/j.bbabio.2008.04.032] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2008] [Revised: 04/16/2008] [Accepted: 04/22/2008] [Indexed: 11/29/2022]
Abstract
NADH-quinone oxidoreductase (complex I) in bovine heart mitochondria has a molecular weight of approximately 1 million Da composed of 45 distinct subunits. It is the largest energy transducing complex so far known. Bacterial complex I is simpler and smaller, but the essential redox components and the basic mechanisms of electron and proton translocation are the same. Over the past three decades, Ohnishi et al. have pursued extensive EPR studies near liquid helium temperatures and characterized most of the iron-sulfur clusters in complex I. Recently, Yakovlev et al. [G. Yakovlev, T. Reda, J. Hirst, Reevaluating the relationship between EPR spectra and enzyme structure for the iron-sulfur clusters in NADH:quinone oxidoreductase, Proc. Natl. Acad. Sci. U. S. A. 104 (2007) 12720-12725] challenged Ohnishi's group by claiming that there were EPR "misassignments" among clusters N4, N5 and N6b (in order to prevent confusion, we used current consensus nomenclature, as the nickname). They claimed that we misassigned EPR signals arising from cluster N5 to cluster N4, and signals from cluster N6b to cluster N4. They also proposed that cluster N5 has (4Cys)-ligands. Based on the accumulated historical data and recent results of our site-specific mutagenesis experiments, we confirmed that cluster N5 has (1His+3Cys)-ligands as we had predicted. We revealed that E. coli cluster N5 signals could be clearly detected at the sample temperature around 3 K with microwave power higher than 5 mW. Thus Hirst's group could not detect N5 signals under any of their EPR conditions, reported in their PNAS paper. It seems that they misassigned the signals from cluster N4 to N5. As to the claim of "misassignment" between clusters N4 and N6b, that was not a possibility because our mutagenesis systems did not contain cluster N6b. Therefore, we believe that we have not made any "misassignment" in our work.
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Affiliation(s)
- Tomoko Ohnishi
- Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6059, USA.
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160
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The mitochondrial impairment, oxidative stress and neurodegeneration connection: reality or just an attractive hypothesis? Trends Neurosci 2008; 31:251-6. [PMID: 18403030 DOI: 10.1016/j.tins.2008.02.008] [Citation(s) in RCA: 182] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2007] [Revised: 02/15/2008] [Accepted: 02/19/2008] [Indexed: 01/26/2023]
Abstract
Aging is the most important risk factor for common neurodegenerative disorders such as Parkinson's and Alzheimer's diseases. Aging in the central nervous system has been associated with elevated mutation load in mitochondrial DNA, defects in mitochondrial respiration and increased oxidative damage. These observations support a 'vicious cycle' theory which states that there is a feedback mechanism connecting these events in aging and age-associated neurodegeneration. Despite being an extremely attractive hypothesis, the bulk of the evidence supporting the mitochondrial vicious cycle model comes from pharmacological experiments in which the modes of mitochondrial enzyme inhibition are far from those observed in real life. Furthermore, recent in vivo evidence does not support this model. In this review, we focus on the relationship among the components of the putative vicious cycle, with particular emphasis on the role of mitochondrial defects on oxidative stress.
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161
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Morgan DJ, Sazanov LA. Three-dimensional structure of respiratory complex I from Escherichia coli in ice in the presence of nucleotides. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:711-8. [PMID: 18433710 DOI: 10.1016/j.bbabio.2008.03.023] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Revised: 03/07/2008] [Accepted: 03/25/2008] [Indexed: 11/24/2022]
Abstract
Complex I (NADH:ubiquinone oxidoreductase) is the largest protein complex of bacterial and mitochondrial respiratory chains. The first three-dimensional structure of bacterial complex I in vitrified ice was determined by electron cryo-microscopy and single particle analysis. The structure of the Escherichia coli enzyme incubated with either NAD(+) (as a reference) or NADH was calculated to 35 and 39 A resolution, respectively. The X-ray structure of the peripheral arm of Thermus thermophilus complex I was docked into the reference EM structure. The model obtained indicates that Fe-S cluster N2 is close to the membrane domain interface, allowing for effective electron transfer to membrane-embedded quinone. At the current resolution, the structures in the presence of NAD(+) or NADH are similar. Additionally, side-view class averages were calculated for the negatively stained bovine enzyme. The structures of bovine complex I in the presence of either NAD(+) or NADH also appeared to be similar. These observations indicate that conformational changes upon reduction with NADH, suggested to occur by a range of studies, are smaller than had been thought previously. The model of the entire bacterial complex I could be built from the crystal structures of subcomplexes using the EM envelope described here.
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Affiliation(s)
- David J Morgan
- Medical Research Council, Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, UK
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162
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Abstract
Complex I, the main entry point for electrons to the respiratory chain, is of critical importance for cellular energy homeostasis. In this issue of Cell Metabolism, Kruse and coworkers (2008) describe the first mouse knockout for a complex I structural subunit, thus advancing our understanding of complex I in disease.
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163
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Schneider D, Pohl T, Walter J, Dörner K, Kohlstädt M, Berger A, Spehr V, Friedrich T. Assembly of the Escherichia coli NADH:ubiquinone oxidoreductase (complex I). BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:735-9. [PMID: 18394423 DOI: 10.1016/j.bbabio.2008.03.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2008] [Accepted: 03/03/2008] [Indexed: 11/19/2022]
Abstract
The proton-pumping NADH:ubiquinone oxidoreductase is the first of the respiratory chain complexes in many bacteria and the mitochondria of most eukaryotes. In general, the bacterial complex consists of 14 different subunits. In addition to the homologues of these subunits, the mitochondrial complex contains approximately 31 additional proteins. While it was shown that the mitochondrial complex is assembled from distinct intermediates, nothing is known about the assembly of the bacterial complex. We used Escherichia coli mutants, in which the nuo-genes coding the subunits of complex I were individually disrupted by an insertion of a resistance cartridge to determine whether they are required for the assembly of a functional complex I. No complex I-mediated enzyme activity was detectable in the mutant membranes and it was not possible to extract a structurally intact complex I from the mutant membranes. However, the subunits and the cofactors of the soluble NADH dehydrogenase fragment of the complex were detected in the cytoplasm of some of the nuo-mutants. It is discussed whether this fragment represents an assembly intermediate. In addition, a membrane-bound fragment exhibiting NADH/ferricyanide oxidoreductase activity and containing the iron-sulfur cluster N2 was detected in one mutant.
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Affiliation(s)
- Daniel Schneider
- Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany
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164
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Esterházy D, King MS, Yakovlev G, Hirst J. Production of reactive oxygen species by complex I (NADH:ubiquinone oxidoreductase) from Escherichia coli and comparison to the enzyme from mitochondria. Biochemistry 2008; 47:3964-71. [PMID: 18307315 DOI: 10.1021/bi702243b] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The generation of reactive oxygen species by mitochondrial complex I (NADH:ubiquinone oxidoreductase) is considered a significant cause of cellular oxidative stress, linked to neuromuscular diseases and aging. Defining its mechanism is important for the formulation of causative connections between complex I defects and pathological effects. Oxygen is probably reduced at two sites in complex I, one associated with NADH oxidation in the mitochondrial matrix and the other associated with ubiquinone reduction in the membrane. Here, we study complex I from Escherichia coli, exploiting similarities and differences in the bacterial and mitochondrial enzymes to extend our knowledge of O2 reduction at the active site for NADH oxidation. E. coli and bovine complex I reduce O2 at essentially the same rate, with the same potential dependence (set by the NAD (+)/NADH ratio), showing that the rate-determining step is conserved. The potential dependent rate of H2O2 production does not correlate to the potential of the distal [2Fe-2S] cluster N1a in E. coli complex I, excluding it as the point of O2 reduction. Therefore, our results confirm previous proposals that O2 reacts with the fully reduced flavin mononucleotide. Assays for superoxide production by E. coli complex I were prone to artifacts, but dihydroethidium reduction showed that, upon reducing O2, it produces approximately 20% superoxide and 80% H2O2. In contrast, bovine complex I produces 95% superoxide. The results are consistent with (but do not prove) a specific role for cluster N1a in determining the outcome of O2 reduction; possible reaction mechanisms are discussed.
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Affiliation(s)
- Daria Esterházy
- Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY, United Kingdom
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165
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Euro L, Bloch DA, Wikström M, Verkhovsky MI, Verkhovskaya M. Electrostatic interactions between FeS clusters in NADH:ubiquinone oxidoreductase (Complex I) from Escherichia coli. Biochemistry 2008; 47:3185-93. [PMID: 18269245 DOI: 10.1021/bi702063t] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The redox properties of the cofactors of NADH:ubiquinone oxidoreductase (complex I) from Escherichia coli were studied by following the changes in electron paramagnetic resonance (EPR) and optical spectra upon electrochemical redox titration of the purified protein. At neutral pH, the FMN cofactor had a midpoint redox potential ( E m) approximately -350 mV ( n = 2). Binuclear FeS clusters were well-characterized: N1a was titrated with a single ( n = 1) transition, and E m = -235 mV. In contrast, the titration of N1b can only be fitted with the sum of at least two one-electron Nernstian curves with E m values of -245 and -320 mV. The tetranuclear clusters can also be separated into two groups, either having a single, n = 1, or more complex redox titration curves. The titration curves of the EPR bands attributed to the tetranuclear clusters N2 ( g = 2.045 and g = 1.895) and N6b ( g = 2.089 and g = 1.877) can be presented by the sum of at least two components, each with E m (app) approximately -200/-300 mV and -235/-315 mV, respectively. The titration of the signals at g = 1.956-1.947 (N3 or N7, E m = -315 mV), g = 2.022, and g = 1.932 (Nx, -365 mV) and the low temperature signal at g = 1.929 (N4 or N5, -330 mV) followed Nernstian n = 1 curves. The observed redox titration curves are discussed in terms of intrinsic electrostatic interactions between FeS centers in complex I. A model showing shifts of E m due to the electrostatic interaction between the centers is presented.
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Affiliation(s)
- Liliya Euro
- Helsinki Bioenergetics Group, Institute of Biotechnology, P.O. Box 65, (Viikinkaari 1) 00014 University of Helsinki, Helsinki, Finland
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166
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Ohnishi T, Ohnishi ST, Shinzawa-Ito K, Yoshikawa S. Functional role of coenzyme Q in the energy coupling of NADH-CoQ oxidoreductase (Complex I): stabilization of the semiquinone state with the application of inside-positive membrane potential to proteoliposomes. Biofactors 2008; 32:13-22. [PMID: 19096096 PMCID: PMC2683760 DOI: 10.1002/biof.5520320103] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Coenzyme Q10 (which is also designated as CoQ10, ubiquinone-10, UQ10, CoQ, UQ or simply as Q) plays an important role in energy metabolism. For NADH-Q oxidoreductase (complex I), Ohnishi and Salerno proposed a hypothesis that the proton pump is operated by the redox-driven conformational change of a Q-binding protein, and that the bound form of semiquinone (SQ) serves as its gate [FEBS Letters 579 (2005) 45-55]. This was based on the following experimental results: (i) EPR signals of the fast-relaxing SQ anion (designated as QNf(.-)) are observable only in the presence of the proton electrochemical potential (DeltamuH+); (ii) iron-sulfur cluster N2 and QNf(.-) are directly spin-coupled; and (iii) their center-to-center distance was calculated as 12angstroms, but QNf(.-) is only 5angstroms deeper than N2 perpendicularly to the membrane. After the priming reduction of Q to QNf(.-), the proton pump operates only in the steps between the semiquinone anion (QNf(.-)) and fully reduced quinone (QH2). Thus, by cycling twice for one NADH molecule, the pump transports 4H+ per 2e(-). This hypothesis predicts the following phenomena: (a) Coupled with the piericidin A sensitive NADH-DBQ or Q1 reductase reaction, DeltamuH+ would be established; (b) DeltamuH+ would enhance the SQ EPR signals; and (c) the dissipation of DeltamuH+ with the addition of an uncoupler would increase the rate of NADH oxidation and decrease the SQ signals. We reconstituted bovine heart complex I, which was prepared at Yoshikawa's laboratory, into proteoliposomes. Using this system, we succeeded in demonstrating that all of these phenomena actually took place. We believe that these results strongly support our hypothesis.
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Affiliation(s)
- Tomoko Ohnishi
- Dept of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
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167
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Vogel RO, Smeitink JAM, Nijtmans LGJ. Human mitochondrial complex I assembly: A dynamic and versatile process. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2007; 1767:1215-27. [PMID: 17854760 DOI: 10.1016/j.bbabio.2007.07.008] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2007] [Revised: 07/24/2007] [Accepted: 07/26/2007] [Indexed: 12/12/2022]
Abstract
One can but admire the intricate way in which biomolecular structures are formed and cooperate to allow proper cellular function. A prominent example of such intricacy is the assembly of the five inner membrane embedded enzymatic complexes of the mitochondrial oxidative phosphorylation (OXPHOS) system, which involves the stepwise combination of >80 subunits and prosthetic groups encoded by both the mitochondrial and nuclear genomes. This review will focus on the assembly of the most complicated OXPHOS structure: complex I (NADH:ubiquinone oxidoreductase, EC 1.6.5.3). Recent studies into complex I assembly in human cells have resulted in several models elucidating a thus far enigmatic process. In this review, special attention will be given to the overlap between the various assembly models proposed in different organisms. Complex I being a complicated structure, its assembly must be prone to some form of coordination. This is where chaperone proteins come into play, some of which may relate complex I assembly to processes such as apoptosis and even immunity.
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Affiliation(s)
- Rutger O Vogel
- Nijmegen Centre for Mitochondrial Disorders, Department of Pediatrics, Radboud University Nijmegen Medical Centre, Geert Grooteplein 10, 6500 HB Nijmegen, The Netherlands
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168
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Grivennikova VG, Kotlyar AB, Karliner JS, Cecchini G, Vinogradov AD. Redox-dependent change of nucleotide affinity to the active site of the mammalian complex I. Biochemistry 2007; 46:10971-8. [PMID: 17760425 PMCID: PMC2258335 DOI: 10.1021/bi7009822] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A very potent and specific inhibitor of mitochondrial NADH:ubiquinone oxidoreductase (complex I), a derivative of NADH (NADH-OH) has recently been discovered (Kotlyar, A. B., Karliner, J. S., and Cecchini, G. (2005) FEBS Lett. 579, 4861-4866). Here we present a quantitative analysis of the interaction of NADH-OH and other nucleotides with oxidized and reduced complex I in tightly coupled submitochondrial particles. Both the rate of the NADH-OH binding and its affinity to complex I are strongly decreased in the presence of succinate. The effect of succinate is completely reversed by rotenone, antimycin A, and uncoupler. The relative affinity of ADP-ribose, a competitive inhibitor of NADH oxidation, is also shown to be significantly affected by enzyme reduction (KD of 30 and 500 microM for oxidized and the succinate-reduced enzyme, respectively). Binding of NADH-OH is shown to abolish the succinate-supported superoxide generation by complex I. Gradual inhibition of the rotenone-sensitive uncoupled NADH oxidase and the reverse electron transfer activities by NADH-OH yield the same final titration point (approximately 0.1 nmol/mg of protein). The titration of NADH oxidase appears as a straight line, whereas the titration of the reverse reaction appears as a convex curve. Possible models to explain the different titration patterns for the forward and reverse reactions are briefly discussed.
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Affiliation(s)
| | - Alexander B. Kotlyar
- * To whom correspondence should be addressed. (A.D.V.) Phone/fax: 7 495 939 1376. E-mail: . (A.B.K.) Phone: (415) 221-4810 ext. 3416. Fax: (415) 750-6959. E-mail:
| | | | | | - Andrei D. Vinogradov
- * To whom correspondence should be addressed. (A.D.V.) Phone/fax: 7 495 939 1376. E-mail: . (A.B.K.) Phone: (415) 221-4810 ext. 3416. Fax: (415) 750-6959. E-mail:
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169
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Abstract
The number of NADH dehydrogenases and their role in energy transduction in
Escherchia coli
have been under debate for a long time. Now it is evident that
E. coli
possesses two respiratory NADH dehydrogenases, or NADH:ubiquinone oxidoreductases, that have traditionally been called NDH-I and NDH-II. This review describes the properties of these two NADH dehydrogenases, focusing on the mechanism of the energy converting NADH dehydrogenase as derived from the high resolution structure of the soluble part of the enzyme. In
E. coli
, complex I operates in aerobic and anaerobic respiration, while NDH-II is repressed under anaerobic growth conditions. The insufficient recycling of NADH most likely resulted in excess NADH inhibiting tricarboxylic acid cycle enzymes and the glyoxylate shunt.
Salmonella enterica
serovar Typhimurium complex I mutants are unable to activate ATP-dependent proteolysis under starvation conditions. NDH-II is a single subunit enzyme with a molecular mass of 47 kDa facing the cytosol. Despite the absence of any predicted transmembrane segment it has to be purified in the presence of detergents, and the activity of the preparation is stimulated by an addition of lipids.
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170
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Yakovlev G, Reda T, Hirst J. Reevaluating the relationship between EPR spectra and enzyme structure for the iron sulfur clusters in NADH:quinone oxidoreductase. Proc Natl Acad Sci U S A 2007; 104:12720-5. [PMID: 17640900 PMCID: PMC1925037 DOI: 10.1073/pnas.0705593104] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
NADH:quinone oxidoreductase (complex I) plays a pivotal role in cellular energy production. It employs a series of redox cofactors to couple electron transfer to the generation of a proton-motive force across the inner mitochondrial or bacterial cytoplasmic membrane. Complex I contains a noncovalently bound flavin mononucleotide at the active site for NADH oxidation and eight or nine iron-sulfur clusters to transfer electrons between the flavin and a quinone-binding site. Understanding the mechanism of complex I requires the properties of these clusters to be defined, both individually and as an ensemble. Most functional information on the clusters has been gained from EPR spectroscopy, but some clusters are not observed by EPR and attributing the observed signals to the structurally defined clusters is difficult. The current consensus picture relies on correlating the spectra from overexpressed subunits (containing one to four clusters) with those from intact complexes I. Here, we analyze spectra from the overexpressed NuoG subunit from Escherichia coli complex I and compare them with spectra from the intact enzyme. Consequently, we propose that EPR signals N4 and N5 have been misassigned: signal N4 is from NuoI (not NuoG) and signal N5 is from the conserved cysteine-ligated [4Fe-4S] cluster in NuoG (not from the cluster with a histidine ligand). The consequences of reassigning the EPR signals and their associated functional information on the free energy profile for electron transfer through complex I are discussed.
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Affiliation(s)
- Gregory Yakovlev
- Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, United Kingdom
| | - Torsten Reda
- Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, United Kingdom
| | - Judy Hirst
- Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, United Kingdom
- To whom correspondence should be addressed. E-mail:
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171
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Clason T, Zickermann V, Ruiz T, Brandt U, Radermacher M. Direct localization of the 51 and 24 kDa subunits of mitochondrial complex I by three-dimensional difference imaging. J Struct Biol 2007; 159:433-42. [PMID: 17591445 PMCID: PMC2700006 DOI: 10.1016/j.jsb.2007.05.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2007] [Revised: 04/27/2007] [Accepted: 05/02/2007] [Indexed: 11/30/2022]
Abstract
Complex I is the largest complex in the respiratory chain, and the least understood. We have determined the 3D structure of complex I from Yarrowia lipolytica lacking the flavoprotein part of the N-module, which consists of the 51 kDa (NUBM) and the 24 kDa (NUHM) subunits. The reconstruction was determined by 3D electron microscopy of single particles. A comparison to our earlier reconstruction of the complete Y. lipolytica complex I clearly assigns the two flavoprotein subunits to an outer lobe of the peripheral arm of complex I. Localizing the two subunits allowed us to fit the X-ray structure of the hydrophilic fragment of complex I from Thermus thermophilus. The fit that is most consistent with previous immuno-electron microscopic data predicts that the ubiquinone reducing catalytic center resides in the second peripheral lobe, while the 75 kDa subunit is placed near the previously seen connection between the peripheral arm and the membrane arm protrusions.
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Affiliation(s)
- Todd Clason
- University of Vermont, College of Medicine, Department Molecular Physiology and Biophysics, Burlington, VT 05405, USA
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