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Mitochondrial iron-sulfur clusters: Structure, function, and an emerging role in vascular biology. Redox Biol 2021; 47:102164. [PMID: 34656823 PMCID: PMC8577454 DOI: 10.1016/j.redox.2021.102164] [Citation(s) in RCA: 98] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/04/2021] [Accepted: 10/08/2021] [Indexed: 12/31/2022] Open
Abstract
Iron-sulfur (Fe-S) clusters are essential cofactors most commonly known for their role mediating electron transfer within the mitochondrial respiratory chain. The Fe-S cluster pathways that function within the respiratory complexes are highly conserved between bacteria and the mitochondria of eukaryotic cells. Within the electron transport chain, Fe-S clusters play a critical role in transporting electrons through Complexes I, II and III to cytochrome c, before subsequent transfer to molecular oxygen. Fe-S clusters are also among the binding sites of classical mitochondrial inhibitors, such as rotenone, and play an important role in the production of mitochondrial reactive oxygen species (ROS). Mitochondrial Fe-S clusters also play a critical role in the pathogenesis of disease. High levels of ROS produced at these sites can cause cell injury or death, however, when produced at low levels can serve as signaling molecules. For example, Ndufs2, a Complex I subunit containing an Fe-S center, N2, has recently been identified as a redox-sensitive oxygen sensor, mediating homeostatic oxygen-sensing in the pulmonary vasculature and carotid body. Fe-S clusters are emerging as transcriptionally-regulated mediators in disease and play a crucial role in normal physiology, offering potential new therapeutic targets for diseases including malaria, diabetes, and cancer.
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2
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Schuller JM, Birrell JA, Tanaka H, Konuma T, Wulfhorst H, Cox N, Schuller SK, Thiemann J, Lubitz W, Sétif P, Ikegami T, Engel BD, Kurisu G, Nowaczyk MM. Structural adaptations of photosynthetic complex I enable ferredoxin-dependent electron transfer. Science 2018; 363:257-260. [PMID: 30573545 DOI: 10.1126/science.aau3613] [Citation(s) in RCA: 127] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 12/06/2018] [Indexed: 12/22/2022]
Abstract
Photosynthetic complex I enables cyclic electron flow around photosystem I, a regulatory mechanism for photosynthetic energy conversion. We report a 3.3-angstrom-resolution cryo-electron microscopy structure of photosynthetic complex I from the cyanobacterium Thermosynechococcus elongatus. The model reveals structural adaptations that facilitate binding and electron transfer from the photosynthetic electron carrier ferredoxin. By mimicking cyclic electron flow with isolated components in vitro, we demonstrate that ferredoxin directly mediates electron transfer between photosystem I and complex I, instead of using intermediates such as NADPH (the reduced form of nicotinamide adenine dinucleotide phosphate). A large rate constant for association of ferredoxin to complex I indicates efficient recognition, with the protein subunit NdhS being the key component in this process.
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Affiliation(s)
- Jan M Schuller
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
| | - James A Birrell
- Max Planck Institute for Chemical Energy Conversion, 45470 Mülheim an der Ruhr, Germany
| | - Hideaki Tanaka
- Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan.,Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan
| | - Tsuyoshi Konuma
- Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Hannes Wulfhorst
- Plant Biochemistry, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44780 Bochum, Germany.,Daiichi Sankyo Deutschland GmbH, Zielstattstr. 48, 81379 München, Germany
| | - Nicholas Cox
- Max Planck Institute for Chemical Energy Conversion, 45470 Mülheim an der Ruhr, Germany.,Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
| | - Sandra K Schuller
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, 81377 Munich, Germany
| | - Jacqueline Thiemann
- Plant Biochemistry, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44780 Bochum, Germany
| | - Wolfgang Lubitz
- Max Planck Institute for Chemical Energy Conversion, 45470 Mülheim an der Ruhr, Germany
| | - Pierre Sétif
- Institut de Biologie Intégrative de la Cellule (I2BC), IBITECS, CEA, CNRS, Université Paris-Saclay, F-91198 Gif-sur-Yvette, France
| | - Takahisa Ikegami
- Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Benjamin D Engel
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Genji Kurisu
- Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan. .,Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan
| | - Marc M Nowaczyk
- Plant Biochemistry, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44780 Bochum, Germany.
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3
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A metabolic-activity-detecting approach to life detection: Restoring a chemostat from stop-feeding using a rapid bioactivity assay. Bioelectrochemistry 2017; 118:147-153. [DOI: 10.1016/j.bioelechem.2017.08.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 08/05/2017] [Accepted: 08/07/2017] [Indexed: 11/22/2022]
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4
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Kohlstädt M, Dörner K, Labatzke R, Koç C, Heilscher R, Schiltz E, Einsle O, Hellwig P, Friedrich T. Heterologous production, isolation, characterization and crystallization of a soluble fragment of the NADH:ubiquinone oxidoreductase (complex I) from Aquifex aeolicus. Biochemistry 2015; 47:13036-45. [PMID: 19006332 DOI: 10.1021/bi801307n] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The proton-pumping NADH:ubiquinone oxidoreductase (complex I) is the first enzyme complex of the respiratory chains in many bacteria and most eukaryotes. It is the least understood of all, due to its enormous size and unique energy conversion mechanism. The bacterial complex is in general made up of 14 different subunits named NuoA-N. Subunits NuoE, -F, and -G comprise the electron input part of the complex. We have cloned these genes from the hyperthermophilic bacterium Aquifex aeolicus and expressed them heterologously in Escherichia coli. A soluble subcomplex made up of NuoE and NuoF and containing the NADH binding site, the primary electron acceptor flavin mononucleotide (FMN), the binuclear iron-sulfur cluster N1a, and the tetranuclear iron-sulfur cluster N3 was isolated by chromatographic methods. The proteins were identified by N-terminal sequencing and mass spectrometry; the cofactors were characterized by UV/vis and EPR spectroscopy. Subunit NuoG was not produced in this strain. The preparation was thermostable and exhibited maximum NADH/ferricyanide oxidoreductase activity at 85 degrees C. Analytical size-exclusion chromatography and dynamic light scattering revealed the homogeneity of the preparation. First attempts to crystallize the preparation led to crystals diffracting more than 2 A.
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Affiliation(s)
- Markus Kohlstädt
- Institut fur Organische Chemie and Biochemie, Albert-Ludwigs-Universitat, Albertstrasse 21, 79104 Freiburg, Germany, and Institut de Chimie UMR 7177, Laboratoire de spectroscopie vib. et electrochimie des biomolecules, CNRS, Universite Louis Pasteur, 4, rue Blaise Pascal, 67070 Strasbourg, France
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The reaction of NADPH with bovine mitochondrial NADH:ubiquinone oxidoreductase revisited: II. Comparison of the proposed working hypothesis with literature data. J Bioenerg Biomembr 2010; 42:279-92. [PMID: 20632077 DOI: 10.1007/s10863-010-9302-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Accepted: 06/21/2010] [Indexed: 10/19/2022]
Abstract
The first purification of bovine NADH:ubiquinone oxidoreductase (Complex I) was reported nearly half a century ago (Hatefi et al. J Biol Chem 237:1676-1680, 1962). The pathway of electron-transfer through the enzyme is still under debate. A major obstacle is the assignment of EPR signals to the individual iron-sulfur clusters in the subunits. The preceding paper described a working model based on the kinetics with NADPH. This model is at variance with current views in the field. The present paper provides a critical overview on the possible causes for the discrepancies. It is concluded that the stability of all purified preparations described thus far, including Hatefi's Complex I, is compromised due to removal of the enzyme from the protective membrane environment. In addition, most preparations described during the last two decades are purified by methods involving synthetic detergents and column chromatography. This results in delipidation, loss of endogenous quinones and loss of reactions with (artificial) quinones in a rotenone-sensitive way. The Fe:FMN ratio's indicate that FMN-a is absent, but that all Fe-S clusters may be present. In contrast to the situation in bovine SMP and Hatefi's Complex I, three of the six expected [4Fe-4S] clusters are not detected in EPR spectra. Qualitatively, the overall EPR lineshape of the remaining three cubane signals may seem similar to that of Hatefi's Complex I, but quantitatively it is not. It is further proposed that point mutations in any of the TYKY, PSST, 49-kDa or 30-kDa subunits, considered to make up the delicate structural heart of Complex I, may have unpredictable effects on any of the other subunits of this quartet. The fact that most point mutations led to inactive enzymes makes a correct interpretation of such mutations even more ambiguous. In none of the Complex-I-containing membrane preparations from non-bovine origin, the pH dependencies of the NAD(P)H-->O(2) reactions and the pH-dependent reduction kinetics of the Fe-S clusters with NADPH have been determined. This excludes a proper discussion on the absence or presence of FMN-a in native Complex I from other organisms.
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Leonard M, Eryl Sharp R, Darrouzet E, Moser C, Ohnishi T, Gibney B, Daldal F, Leslie Dutton P. Coenzyme Q Oxidation Reduction Reactions in Mitochondrial Electron Transport. ACTA ACUST UNITED AC 2010. [DOI: 10.1201/9781420036701.sec1b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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7
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Ernsting BR, Edwards DD, Aldred KJ, Fites JS, Neff CR. Mitochondrial genome sequence of Unionicola foili (Acari: Unionicolidae): a unique gene order with implications for phylogenetic inference. EXPERIMENTAL & APPLIED ACAROLOGY 2009; 49:305-316. [PMID: 19353278 DOI: 10.1007/s10493-009-9263-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2008] [Accepted: 03/22/2009] [Indexed: 05/27/2023]
Abstract
The mitochondrial genome of Unionicola foili is circular, 14,738 bp in length, and contains several notable features. The sequence and annotation revealed a unique gene order, continuing a pattern of highly rearranged mitochondrial genomes in the Trombidiformes. U. foili mitochondrial tRNA sequences predict non-canonical secondary structures for these molecules, and our annotation suggests an in-frame fusion between the nad4L and nad5 genes in this genome. The unique gene order and unusual tRNA structures could serve as idiosyncratic characters and have the potential to be phylogenetically informative.
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Affiliation(s)
- Brian R Ernsting
- Department of Biology, University of Evansville, Evansville, IN 47722, USA.
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Chandran K, Aggarwal D, Migrino RQ, Joseph J, McAllister D, Konorev EA, Antholine WE, Zielonka J, Srinivasan S, Avadhani NG, Kalyanaraman B. Doxorubicin inactivates myocardial cytochrome c oxidase in rats: cardioprotection by Mito-Q. Biophys J 2009; 96:1388-98. [PMID: 19217856 DOI: 10.1016/j.bpj.2008.10.042] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2008] [Accepted: 10/09/2008] [Indexed: 12/23/2022] Open
Abstract
Doxorubicin (DOX) is used for treating various cancers. Its clinical use is, however, limited by its dose-limiting cardiomyopathy. The exact mechanism of DOX-induced cardiomyopathy still remains unknown. The goals were to investigate the molecular mechanism of DOX-induced cardiomyopathy and cardioprotection by mitoquinone (Mito-Q), a triphenylphosphonium-conjugated analog of coenzyme Q, using a rat model. Rats were treated with DOX, Mito-Q, and DOX plus Mito-Q for 12 weeks. The left ventricular function as measured by two-dimensional echocardiography decreased in DOX-treated rats but was preserved during Mito-Q plus DOX treatment. Using low-temperature ex vivo electron paramagnetic resonance (EPR), a time-dependent decrease in heme signal was detected in heart tissues isolated from rats administered with a cumulative dose of DOX. DOX attenuated the EPR signals characteristic of the exchange interaction between cytochrome c oxidase (CcO)-Fe(III) heme a3 and CuB. DOX and Mito-Q together restored these EPR signals and the CcO activity in heart tissues. DOX strongly downregulated the stable expression of the CcO subunits II and Va and had a slight inhibitory effect on CcO subunit I gene expression. Mito-Q restored CcO subunit II and Va expressions in DOX-treated rats. These results suggest a novel cardioprotection mechanism by Mito-Q during DOX-induced cardiomyopathy involving CcO.
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Affiliation(s)
- Karunakaran Chandran
- Department of Biophysics and Free Radical Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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Maly T, Zwicker K, Cernescu A, Brandt U, Prisner TF. New pulsed EPR methods and their application to characterize mitochondrial complex I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:584-92. [PMID: 19366602 DOI: 10.1016/j.bbabio.2009.02.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Revised: 02/04/2009] [Accepted: 02/05/2009] [Indexed: 10/21/2022]
Abstract
Electron Paramagnetic Resonance (EPR) spectroscopy is the method of choice to study paramagnetic cofactors that often play an important role as active centers in electron transfer processes in biological systems. However, in many cases more than one paramagnetic species is contributing to the observed EPR spectrum, making the analysis of individual contributions difficult and in some cases impossible. With time-domain techniques it is possible to exploit differences in the relaxation behavior of different paramagnetic species to distinguish between them and separate their individual spectral contribution. Here we give an overview of the use of pulsed EPR spectroscopy to study the iron-sulfur clusters of NADH:ubiquinone oxidoreductase (complex I). While FeS cluster N1 can be studied individually at a temperature of 30 K, this is not possible for FeS cluster N2 due to its severe spectral overlap with cluster N1. In this case Relaxation Filtered Hyperfine (REFINE) spectroscopy can be used to separate the overlapping spectra based on differences in their relaxation behavior.
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Affiliation(s)
- Thorsten Maly
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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10
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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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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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Abstract
NADH:quinone oxidoreductase (complex I) pumps protons across the inner membrane of mitochondria or the plasma membrane of many bacteria. Human complex I is involved in numerous pathological conditions and degenerative processes. With 14 central and up to 32 accessory subunits, complex I is among the largest membrane-bound protein assemblies. The peripheral arm of the L-shaped molecule contains flavine mononucleotide and eight or nine iron-sulfur clusters as redox prosthetic groups. Seven of the iron-sulfur clusters form a linear electron transfer chain between flavine and quinone. In most organisms, the seven most hydrophobic subunits forming the core of the membrane arm are encoded by the mitochondrial genome. Most central subunits have evolved from subunits of different hydrogenases and bacterial Na+/H+ antiporters. This evolutionary origin is reflected in three functional modules of complex I. The coupling mechanism of complex I most likely involves semiquinone intermediates that drive proton pumping through redox-linked conformational changes.
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Affiliation(s)
- Ulrich Brandt
- Universität Frankfurt, Fachbereich Medizin, Zentrum der Biologischen Chemie, D-60590 Frankfurt am Main, Germany.
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Maly T, Grgic L, Zwicker K, Zickermann V, Brandt U, Prisner T. Cluster N1 of complex I from Yarrowia lipolytica studied by pulsed EPR spectroscopy. J Biol Inorg Chem 2006; 11:343-50. [PMID: 16502321 DOI: 10.1007/s00775-006-0081-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2005] [Accepted: 01/16/2006] [Indexed: 11/27/2022]
Abstract
After reduction with nicotinamide adenine dinucleotide (NADH), NADH:ubiquinone oxidoreductase (complex I) of the strictly aerobic yeast Yarrowia lipolytica shows clear signals from five different paramagnetic iron-sulfur (FeS) clusters (N1-N5) which can be detected using electron paramagnetic resonance (EPR) spectroscopy. The ligand environment and the assignment of several FeS clusters to specific binding motifs found in several subunits of the complex are still under debate. In order to characterize the hyperfine interaction of the surrounding nuclei with FeS cluster N1, one- and two-dimensional electron spin echo envelope modulation experiments were performed at a temperature of 30 K. At this temperature only cluster N1 contributes to the overall signal in a pulsed EPR experiment. The hyperfine and quadrupole tensors of a nitrogen nucleus and the isotropic and dipolar hyperfine couplings of two sets of protons could be determined by numerical simulation of the one- and two-dimensional spectra. The values obtained are in perfect agreement with a ferredoxin-like binding structure by four cysteine amino acid residues and allow the assignment of the nitrogen couplings to a backbone nitrogen nucleus and the proton couplings to the beta-protons of the bound cysteine residues.
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Affiliation(s)
- T Maly
- Institut für Physikalische und Theoretische Chemie and Center for Biological Magnetic Resonance, Johann-Wolfgang-Goethe-Universität Frankfurt, 60439, Frankfurt am Main, Germany
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Duarte M, Schulte U, Ushakova AV, Videira A. Neurospora strains harboring mitochondrial disease-associated mutations in iron-sulfur subunits of complex I. Genetics 2005; 171:91-9. [PMID: 15956670 PMCID: PMC1456533 DOI: 10.1534/genetics.105.041517] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We subjected the genes encoding the 19.3-, 21.3c-, and 51-kDa iron-sulfur subunits of respiratory chain complex I from Neurospora crassa to site-directed mutagenesis to mimic mutations in human complex I subunits associated with mitochondrial diseases. The V135M substitution was introduced into the 19.3-kDa cDNA, the P88L and R111H substitutions were separately introduced into the 21.3c-kDa cDNA, and the A353V and T435M alterations were separately introduced into the 51-kDa cDNA. The altered cDNAs were expressed in the corresponding null-mutants under the control of a heterologous promoter. With the exception of the A353V polypeptide, all mutated subunits were able to promote assembly of a functional complex I, rescuing the phenotypes of the respective null-mutants. Complex I from these strains displays spectroscopic and enzymatic properties similar to those observed in the wild-type strain. A decrease in total complex I amounts may be the major impact of the mutations, although expression levels of mutant genes from the heterologous promoter were sometimes lower and may also account for complex I levels. We discuss these findings in relation to the involvement of complex I deficiencies in mitochondrial disease.
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Affiliation(s)
- Margarida Duarte
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Portugal
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Brandt U, Kerscher S, Dröse S, Zwicker K, Zickermann V. Proton pumping by NADH:ubiquinone oxidoreductase. A redox driven conformational change mechanism? FEBS Lett 2003; 545:9-17. [PMID: 12788486 DOI: 10.1016/s0014-5793(03)00387-9] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The modular evolutionary origin of NADH:ubiquinone oxidoreductase (complex I) provides useful insights into its functional organization. Iron-sulfur cluster N2 and the PSST and 49 kDa subunits were identified as key players in ubiquinone reduction and proton pumping. Structural studies indicate that this 'catalytic core' region of complex I is clearly separated from the membrane. Complex I from Escherichia coli and Klebsiella pneumoniae was shown to pump sodium ions rather than protons. These new insights into structure and function of complex I strongly suggest that proton or sodium pumping in complex I is achieved by conformational energy transfer rather than by a directly linked redox pump.
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Affiliation(s)
- Ulrich Brandt
- Universität Frankfurt, Fachbereich Medizin, Institut für Biochemie I, Theodor-Stern-Kai 7, Haus 25B, D-60590 Frankfurt am Main, Germany.
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16
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Videira A, Duarte M. From NADH to ubiquinone in Neurospora mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1555:187-91. [PMID: 12206913 DOI: 10.1016/s0005-2728(02)00276-1] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The respiratory chain of the mitochondrial inner membrane includes a proton-pumping enzyme, complex I, which catalyses electron transfer from NADH to ubiquinone. This electron pathway occurs through a series of protein-bound prosthetic groups, FMN and around eight iron-sulfur clusters. The high number of polypeptide subunits of mitochondrial complex I, around 40, have a dual genetic origin. Neurospora crassa has been a useful genetic model to characterise complex I. The characterisation of mutants in specific proteins helped to understand the elaborate processes of the biogenesis, structure and function of the oligomeric enzyme. In the fungus, complex I seems to be dispensable for vegetative growth but required for sexual development. N. crassa mitochondria also contain three to four nonproton-pumping alternative NAD(P)H dehydrogenases. One of them is located in the outer face of the inner mitochondrial membrane, working as a calcium-dependent oxidase of cytosolic NADPH.
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Affiliation(s)
- Arnaldo Videira
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.
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Kerscher S, Dröse S, Zwicker K, Zickermann V, Brandt U. Yarrowia lipolytica, a yeast genetic system to study mitochondrial complex I. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1555:83-91. [PMID: 12206896 DOI: 10.1016/s0005-2728(02)00259-1] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The obligate aerobic yeast Yarrowia lipolytica is introduced as a powerful new model for the structural and functional analysis of mitochondrial complex I. A brief introduction into the biology and the genetics of this nonconventional yeast is given and the relevant genetic tools that have been developed in recent years are summarized. The respiratory chain of Y. lipolytica contains complexes I-IV, one "alternative" NADH-dehydrogenase (NDH2) and a non-heme alternative oxidase (AOX). Because the NADH binding site of NDH2 faces the mitochondrial intermembrane space rather than the matrix, complex I is an essential enzyme in Y. lipolytica. Nevertheless, complex I deletion strains could be generated by attaching the targeting sequence of a matrix protein, thereby redirecting NDH2 to the matrix side. Deletion strains for several complex I subunits have been constructed that can be complemented by shuttle plasmids carrying the deleted gene. Attachment of a hexa-histidine tag to the NUGM (30 kDa) subunit allows fast and efficient purification of complex I from Y. lipolytica by affinity-chromatography. The purified complex has lost most of its NADH:ubiquinone oxidoreductase activity, but is almost fully reactivated by adding 400-500 molecules of phosphatidylcholine per complex I. The established set of genetic tools has proven useful for the site-directed mutagenesis of individual subunits of Y. lipolytica complex I. Characterization of a number of mutations already allowed for the identification of several functionally important amino acids, demonstrating the usefulness of this approach.
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Affiliation(s)
- Stefan Kerscher
- Universitätsklinikum Frankfurt, Institut für Biochemie I, Zentrum der Biologischen Chemie, Theodor-Stern-Kai 7, Haus 25 B, D-60590 Frankfurt am Main, Germany
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18
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Duarte M, Pópulo H, Videira A, Friedrich T, Schulte U. Disruption of iron-sulphur cluster N2 from NADH: ubiquinone oxidoreductase by site-directed mutagenesis. Biochem J 2002; 364:833-9. [PMID: 12049648 PMCID: PMC1222633 DOI: 10.1042/bj20011750] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We have cloned and inactivated, by repeat-induced point mutations, the nuclear gene encoding the 19.3 kDa subunit of complex I (EC 1.6.5.3) from Neurospora crassa, the homologue of the bovine PSST polypeptide. Mitochondria from mutant nuo19.3 lack the peripheral arm of complex I while its membrane arm accumulates. Transformation with wild-type cDNA rescues this phenotype and assembly of complex I is restored. To interfere with assembly of a proposed bound iron-sulphur cluster, site-directed mutants were constructed by introducing cDNA with altered codons for two adjacent cysteines, Cys-101 and Cys-102. The mutant complexes were purified and their enzymic activities and EPR and UV/visible spectra were analysed. Either of the mutations abolishes assembly of iron-sulphur cluster N2, showing that this redox group is bound to the 19.3 kDa protein. We also observed an interference with the reduction of redox group X, suggesting that cluster N2 is the electron donor to this high-potential redox group.
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Affiliation(s)
- Margarida Duarte
- Instituto de Biologia Molecular e Celular, Rua do Campo Alegre 823, 4150-180 Porto, Portugal
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19
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Magnitsky S, Toulokhonova L, Yano T, Sled VD, Hägerhäll C, Grivennikova VG, Burbaev DS, Vinogradov AD, Ohnishi T. EPR characterization of ubisemiquinones and iron-sulfur cluster N2, central components of the energy coupling in the NADH-ubiquinone oxidoreductase (complex I) in situ. J Bioenerg Biomembr 2002; 34:193-208. [PMID: 12171069 DOI: 10.1023/a:1016083419979] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The proton-translocating NADH-ubiquinone oxidoreductase (complex I) is the largest and least understood respiratory complex. The intrinsic redox components (FMN and iron-sulfur clusters) reside in the promontory part of the complex. Ubiquinone is the most possible key player in proton-pumping reactions in the membrane part. Here we report the presence of three distinct semiquinone species in complex I in situ, showing widely different spin relaxation profiles. As our first approach, the semiquinone forms were trapped during the steady state NADH-ubiquinone-1 (Q1) reactions in the tightly coupled, activated bovine heart submitochondrial particles, and were named SQNf (fast-relaxing component), SQNS (slow-relaxing), and SQNx (very slow relaxing). This indicates the presence of at least three different quinone-binding sites in complex I. In the current study, special attention was placed on the SQNf, because of its high sensitivities to DeltamicroH+ and to specific complex I inhibitors (rotenone and piericidin A) in a unique manner. Rotenone inhibits the forward electron transfer reaction more strongly than the reverse reaction, while piericidine A inhibits both reactions with a similar potency. Rotenone quenched the SQNf signal at a much lower concentration than that required to quench the slower relaxing components (SQNs and SQNx). A close correlation was shown between the line shape alteration of the g// = 2.05 signal of the cluster N2 and the quenching of the SQNf signal, using two different experimental approaches: (1) changing the DeltamicroH+ poise by the oligomycin titration which decreases proton leak across the SMP membrane; (2) inhibiting the reverse electron transfer with different concentrations of rotenone. These new experimental results further strengthen our earlier proposal that a direct spin-coupling occurs between SQNf and cluster N2. We discuss the implications of these findings in connection with the energy coupling mechanism in complex .
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Affiliation(s)
- Sergey Magnitsky
- Department of Biochemistry and Biophysics, Medical School, University of Pennsylvania, Philadelphia 19104-6059, USA
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20
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Schultz BE, Chan SI. Structures and proton-pumping strategies of mitochondrial respiratory enzymes. ANNUAL REVIEW OF BIOPHYSICS AND BIOMOLECULAR STRUCTURE 2001; 30:23-65. [PMID: 11340051 DOI: 10.1146/annurev.biophys.30.1.23] [Citation(s) in RCA: 192] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Enzymes of the mitochondrial respiratory chain serve as proton pumps, using the energy made available from electron transfer reactions to transport protons across the inner mitochondrial membrane and create an electrochemical gradient used for the production of ATP. The ATP synthase enzyme is reversible and can also serve as a proton pump by coupling ATP hydrolysis to proton translocation. Each of the respiratory enzymes uses a different strategy for performing proton pumping. In this work, the strategies are described and the structural bases for the action of these proteins are discussed in light of recent crystal structures of several respiratory enzymes. The mechanisms and efficiency of proton translocation are also analyzed in terms of the thermodynamics of the substrate transformations catalyzed by these enzymes.
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Affiliation(s)
- B E Schultz
- Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125, USA
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21
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Videir A, Duarte M. On complex I and other NADH:ubiquinone reductases of Neurospora crassa mitochondria. J Bioenerg Biomembr 2001; 33:197-203. [PMID: 11695829 DOI: 10.1023/a:1010778802236] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The mitochondrial complex I is the first component of the respiratory chain coupling electron transfer from NADH to ubiquinone to proton translocation across the inner membrane of the organelle. The enzyme from the fungus Neurospora crassa is similar to that of other organisms in terms of protein and prosthetic group composition, structure, and function. It contains a high number of polypeptide subunits of dual genetic origin. Most of its subunits were cloned, including those binding redox groups. Extensive gene disruption experiments were conducted, revealing many aspects of the structure, function, and biogenesis of complex I. Complex I is essential for the sexual phase of the life cycle of N. crassa, but not for the asexual stage. In addition to complex I, the fungal mitochondria contain at least three nonproton-pumping alternative NAD(P)H dehydrogenases feeding electrons to the respiratory chain from either matrix or cytosolic substrates.
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Affiliation(s)
- A Videir
- Instituto de Biologia Molecular e Celular, Porto, Portugal.
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22
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Kerscher S, Kashani-Poor N, Zwicker K, Zickermann V, Brandt U. Exploring the catalytic core of complex I by Yarrowia lipolytica yeast genetics. J Bioenerg Biomembr 2001; 33:187-96. [PMID: 11695828 DOI: 10.1023/a:1010726818165] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We have developed Yarrowia lipolytica as a model system to study mitochondrial complex I that combines the application of fast and convenient yeast genetics with efficient structural and functional analysis of its very stable complex I isolated by his-tag affinity purification with high yield. Guided by a structural model based on homologies between complex I and [NiFe] hydrogenases mutational analysis revealed that the 49 kDa subunit plays a central functional role in complex I. We propose that critical parts of the catalytic core of complex I have evolved from the hydrogen reactive site of [NiFe] hydrogenases and that iron-sulfur cluster N2 resides at the interface between the 49 kDa and PSST subunits. These findings are in full agreement with the "semiquinone switch" mechanism according to which coupling of electron and proton transfer in complex I is achieved by a single integrated pump comprising cluster N2, the binding site for substrate ubiquinone, and a tightly bound quinone or quinoid group.
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Affiliation(s)
- S Kerscher
- Universitätsklinikum Frankfurt, Institut für Biochemie I, Zentrum der Biologischen Chemie, Frankfurt am Main, Germany
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23
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Djafarzadeh R, Kerscher S, Zwicker K, Radermacher M, Lindahl M, Schägger H, Brandt U. Biophysical and structural characterization of proton-translocating NADH-dehydrogenase (complex I) from the strictly aerobic yeast Yarrowia lipolytica. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1459:230-8. [PMID: 10924914 DOI: 10.1016/s0005-2728(00)00154-7] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Mitochondrial proton-translocating NADH-dehydrogenase (complex I) is one of the largest and most complicated membrane bound protein complexes. Despite its central role in eukaryotic oxidative phosphorylation and its involvement in a broad range of human disorders, little is known about its structure and function. Therefore, we have started to use the powerful genetic tools available for the strictly aerobic yeast Yarrowia lipolytica to study this respiratory chain enzyme. To establish Y. lipolytica as a model system for complex I, we purified and characterized the multisubunit enzyme from Y lipolytica and sequenced the nuclear genes coding for the seven central subunits of its peripheral part. Complex I from Y lipolytica is quite stable and could be isolated in a highly pure and monodisperse state. One binuclear and four tetranuclear iron-sulfur clusters, including N5, which was previously known only from mammalian mitochondria, were detected by EPR spectroscopy. Initial structural analysis by single particle electron microscopy in negative stain and ice shows complex I from Y. lipolytica as an L-shaped particle that does not exhibit a thin stalk between the peripheral and the membrane parts that has been observed in other systems.
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Affiliation(s)
- R Djafarzadeh
- Universitätsklinikum Frankfurt, Institut für Biochemie I, Zentrum der Biologischen Chemie, Frankfurt am Main, Germany
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24
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Schulte U, Haupt V, Abelmann A, Fecke W, Brors B, Rasmussen T, Friedrich T, Weiss H. A reductase/isomerase subunit of mitochondrial NADH:ubiquinone oxidoreductase (complex I) carries an NADPH and is involved in the biogenesis of the complex. J Mol Biol 1999; 292:569-80. [PMID: 10497022 DOI: 10.1006/jmbi.1999.3096] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Respiratory chains of bacteria and mitochondria contain closely related forms of the proton-pumping NADH:ubiquinone oxidoreductase, or complex I. The bacterial complex I consists of 14 subunits, whereas the mitochondrial complex contains some 25 extra subunits in addition to the homologues of the bacterial subunits. One of these extra subunits with a molecular mass of 40 kDa belongs to a heterogeneous family of reductases/isomerases with a conserved nucleotide binding site. We deleted this subunit in Neurospora crassa by gene disruption. In the mutant nuo 40, a complex I lacking the 40 kDa subunit is assembled. The mutant complex I does not contain tightly bound NADPH present in wild-type complex I. This NADPH cofactor is not connected to the respiratory electron pathway of complex I. The mutant complex has normal NADH dehydrogenase activity and contains the redox groups known for wild-type complex I, one flavin mononucleotide and four iron-sulfur clusters detectable by electron paramagnetic resonance spectroscopy. In the mutant complex these groups are all readily reduced by NADH. However, the mutant complex is not capable of reducing ubiquinone. A recently described redox group identified in wild-type complex I by UV-visible spectroscopy is not detectable in the mutant complex. We propose that the reductase/isomerase subunit with its NADPH cofactor takes part in the biosynthesis of this new redox group.
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Affiliation(s)
- U Schulte
- Institut für Biochemie, Heinrich-Heine-Universität, Düsseldorf, Germany.
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25
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Sousa R, Barquera B, Duarte M, Finel M, Videira A. Characterisation of the last Fe-S cluster-binding subunit of Neurospora crassa complex I. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1411:142-6. [PMID: 10216160 DOI: 10.1016/s0005-2728(99)00014-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We have cloned cDNAs encoding the last iron-sulphur protein of complex I from Neurospora crassa. The cDNA sequence contains an open reading frame that codes for a precursor polypeptide of 226 amino acid residues with a molecular mass of 24972 Da. Our results indicate that the mature protein belongs probably to the peripheral arm of complex I and is rather unstable when not assembled into the enzyme. The protein is highly homologous to the PSST subunit of bovine complex I, the most likely candidate to bind iron-sulphur cluster N-2. All the amino acid residues proposed to bind such a cluster are conserved in the fungal protein.
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Affiliation(s)
- R Sousa
- Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Porto, Portugal
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26
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Pereira MM, Carita JN, Teixeira M. Membrane-bound electron transfer chain of the thermohalophilic bacterium Rhodothermus marinus: characterization of the iron-sulfur centers from the dehydrogenases and investigation of the high-potential iron-sulfur protein function by in vitro reconstitution of the respiratory chain. Biochemistry 1999; 38:1276-83. [PMID: 9930988 DOI: 10.1021/bi981807v] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Rhodothermus marinus, a thermohalophilic bacterium, has a unique electron-transfer chain, containing, besides a cbb3 and a caa3 terminal oxidases, a novel cytochrome bc complex [Pereira, M. M., Carita, J. N., and Teixeira, M. (1999) Biochemistry 38, 1268-1275]. The membrane-bound iron-sulfur centers of this bacterium were studied by electron paramagnetic resonance (EPR) spectroscopy, leading to the identification of its main electron-transfer complexes. The resonances typical for the Rieske-type centers are not detected. Clusters S1 and S3 from succinate dehydrogenase were identified; interestingly, center S3 is shown to be present in two different conformations, with g values at 2.035, 2.009, and 2.001 and at 2.025, 2.002, and 2.000. Upon addition of NADH and dithionite, EPR signals assigned to resonances characteristic of binuclear and tetranuclear clusters develop and are attributed to the iron-sulfur centers of complexes I and II. A high-potential iron-sulfur protein- (HiPIP-) type center previously detected in the membranes of this bacterium [Pereira et al. (1994) FEBS Lett. 352, 327-330] is shown to belong indeed to a canonical HiPIP. This protein was purified and extensively characterized. It is a small water-soluble protein of approximately 10 kDa, containing a single [4Fe-4S]3+/2+ cluster. The reduction potential, determined by EPR redox titrations in intact and detergent-solubilized membranes as well as by cyclic voltammetry in solution, has a pH-independent value of 260 +/- 20 mV, in the range 6-9. In vitro reconstitution of the R. marinus electron-transfer chain shows that the HiPIP plays a fundamental role in the chain, as the electron shuttle between R. marinus cytochrome bc complex and the caa3 terminal oxidase, being thus simultaneously identified a HiPIP reductase and a HiPIP oxidase.
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Affiliation(s)
- M M Pereira
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, APT 127, 2780 Oeiras, Portugal
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Friedrich T, Abelmann A, Brors B, Guénebaut V, Kintscher L, Leonard K, Rasmussen T, Scheide D, Schlitt A, Schulte U, Weiss H. Redox components and structure of the respiratory NADH:ubiquinone oxidoreductase (complex I). BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1365:215-9. [PMID: 9693737 DOI: 10.1016/s0005-2728(98)00070-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The proton-pumping NADH:ubiquinone oxidoreductase is the first complex in the respiratory chains of many purple bacteria and of mitochondria of most eucaryotes. The bacterial complex consists of 14 different subunits. The mitochondrial complex contains at least 29 additional proteins that do not directly participate in electron transfer and proton translocation. We analysed electron micrographs of isolated and negatively stained complex I particles from Escherichia coli and Neurospora crassa and obtained three-dimensional models of both complexes at medium resolution. Both have the same L-shaped overall structure with a peripheral arm protruding into the aqueous phase and a membrane arm extending into the membrane. The two arms of the bacterial complex are only slightly shorter than those of the mitochondrial complex although the protein mass of the former is only half of that of the latter. The presence of a novel redox group in the membrane arm of the complex is discussed. This group has been detected in the N. crassa complex by means of UV-visible spectroscopy. After reduction with an excess of NADH and reoxidation by the lactate dehydrogenase reaction, a reduced-minus-oxidized difference spectrum was obtained that cannot be attributed to the known cofactors flavin mononucleotide (FMN) and the FeS clusters N1, N2, N3 and N4. Due to its positive midpoint potential the novel group is believed to transfer electrons from the FeS clusters to ubiquinone. Its role in proton translocation is discussed.
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Affiliation(s)
- T Friedrich
- Institut für Biochemie, Universität Düsseldorf, Germany.
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28
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Abstract
NADH-quinone 1 oxidoreductase (Complex I) isolated from bovine heart mitochondria was, until recently, the major source for the study of this most complicated energy transducing device in the mitochondrial respiratory chain. Complex I has been shown to contain 43 subunits and possesses a molecular mass of about 1 million. Recently, Complex I genes have been cloned and sequenced from several bacterial sources including Escherichia coli, Paracoccus denitrificans, Rhodobacter capsulatus and Thermus thermophilus HB-8. These enzymes are less complicated than the bovine enzyme, containing a core of 13 or 14 subunits homologous to the bovine heart Complex I. From this data, important clues concerning the subunit location of both the substrate binding site and intrinsic redox centers have been gleaned. Powerful molecular genetic approaches used in these bacterial systems can identify structure/function relationships concerning the redox components of Complex I. Site-directed mutants at the level of bacterial chromosomes and over-expression and purification of single subunits have allowed detailed analysis of the amino acid residues involved in ligand binding to several iron-sulfur clusters. Therefore, it has become possible to examine which subunits contain individual iron-sulfur clusters, their location within the enzyme and what their ligand residues are. The discovery of g=2.00 EPR signals arising from two distinct species of semiquinone (SQ) in the activated bovine heart submitochondrial particles (SMP) is another line of recent progress. The intensity of semiquinone signals is sensitive to DeltamicroH+ and is diminished by specific inhibitors of Complex I. To date, semiquinones similar to those reported for the bovine heart mitochondrial Complex I have not yet been discovered in the bacterial systems. This mini-review describes three aspects of the recent progress in the study of the redox components of Complex I: (A) the location of the substrate (NADH) binding site, flavin, and most of the iron-sulfur clusters, which have been identified in the hydrophilic electron entry domain of Complex I; (B) experimental evidence indicating that the cluster N2 is located in the amphipathic domain of Complex I, connecting the promontory and membrane parts. Very recent data is also presented suggesting that the cluster N2 may have a unique ligand structure with an atypical cluster-ligation sequence motif located in the NuoB (NQO6/PSST) subunit rather than in the long advocated NuoI (NQO9/TYKY) subunit. The latter subunit contains the most primordial sequence motif for two tetranuclear clusters; (C) the discovery of spin-spin interactions between cluster N2 and two distinct Complex I-associated species of semiquinone. Based on the splitting of the g1 signal of the cluster N2 and concomitant strong enhancement of the semiquinone spin relaxation, one semiquinone species was localized 8-11 A from the cluster N2 within the inner membrane on the matrix side (N-side). Spin relaxation of the other semiquinone species is much less enhanced, and thus it was proposed to have a longer distance from the cluster N2, perhaps located closer to the other side (P-side) surface of the membrane. A brief introduction of EPR technique was also described in Appendix A of this mini-review.
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Affiliation(s)
- T Ohnishi
- Johnson Research Foundation, Department of Biochemistry and Biophysics, and the University of Pennsylvania, Philadelphia, PA 19104, USA.
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29
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Abstract
Respiratory chain complex I is a complicated enzyme of mitochondria, that couples electron transfer from NADH to ubiquinone to the proton translocation across the inner membrane of the organelle. The fungus Neurospora crassa has been used as one of the main model organisms to study this enzyme. Complex I is composed of multiple polypeptide subunits of dual genetic origin and contains several prosthetic groups involved in its activity. Most subunits have been cloned and those binding redox centres have been identified. Yet, the functional role of certain complex I proteins remains unknown. Insight into the possible origin and the mechanisms of complex I assembly has been gained. Several mutant strains of N. crassa, in which specific subunits of complex I were disrupted, have been isolated and characterised. This review concerns many aspects of the structure, function and biogenesis of complex I that are being elucidated.
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Affiliation(s)
- A Videira
- Instituto de Biologia Molecular e Celular and Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Porto, Portugal.
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30
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Finel M. Organization and evolution of structural elements within complex I. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1364:112-21. [PMID: 9593850 DOI: 10.1016/s0005-2728(98)00022-x] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- M Finel
- Helsinki Bioenergetics Group, Department of Medical Chemistry, Institute of Biomedicine, University of Helsinki, Helsinki, Finland.
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31
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Dutton PL, Moser CC, Sled VD, Daldal F, Ohnishi T. A reductant-induced oxidation mechanism for complex I. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1364:245-57. [PMID: 9593917 DOI: 10.1016/s0005-2728(98)00031-0] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A model for energy conversion in Complex I is proposed that is a conservative expansion of Mitchell's Q-cycle using a simple mechanistic variation of that already established experimentally for Complex III. The model accommodates the following proposals. (1) The large number of flavin and iron-sulfur redox cofactors integral to Complex I form a simple but long electron transfer chain guiding submillisecond electron transfer from substrate NADH in the matrix to the [4Fe-4S] cluster N2 close to the matrix-membrane interface. (2) The reduced N2 cluster injects a single electron into a ubiquinone (Q) drawn from the membrane pool into a nearby Qnz site, generating an unstable transition state semiquinone (SQ). The generation of a SQ species is the primary step in the energy conversion process in Complex I, as in Complex III. In Complex III, the SQ at the Qo site near the cytosolic side acts as a strong reductant to drive electronic charge across the membrane profile via two hemes B to a Qi site near the matrix side. We propose that in Complex I, the SQ at the Qnz site near the matrix side acts as a strong oxidant to pull electronic charge across the membrane profile via a quinone (Qny site) from a Qnx site near the cytosolic side. The opposing locations of matrix side Qnz and cytosolic side Qo, together with the opposite action of Qnz as an oxidant rather than a reductant, renders the Complex I and III processes vectorially and energetically complementary. The redox properties of the Qnz and Qo site occupants can be identical. (3) The intervening Qny site of Complex I acts as a proton pumping element (akin to the proton pump of Complex IV), rather than the simple electron guiding hemes B of Complex III. Thus the transmembrane action of Complex I doubles to four (or more) the number of protons and charges translocated per NADH oxidized and Q reduced. The Qny site does not exchange with the pool and may even be covalently bound. (4) The Qnx site on the cytosol side of Complex I is complementary to the Qi site on the matrix side of Complex III and can have the same redox properties. The Qnx site draws QH2 from the membrane pool to be oxidized in two single electron steps. Besides explaining earlier observations and making testable predictions, this Complex I model re-establishes a uniformity in the mechanisms of respiratory energy conversion by using engineering principles common to Complexes III and IV: (1) all the primary energy coupling reactions in the different complexes use oxygen chemistry in the guise of dioxygen or ubiquinone, (2) these reactions are highly localized structurally, utilizing closely placed catalytic redox cofactors, (3) these reactions are also highly localized energetically, since virtually all the free energy defined by substrates is conserved in the form of transition state that initiates the transmembrane action and (4) all complexes possess apparently supernumerary oxidation-reduction cofactors which form classical electron transfer chains that operate with high directional specificity to guide electron at near zero free energies to and from the sites of localized coupling.
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Affiliation(s)
- P L Dutton
- The Johnson Research Foundation and Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA.
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32
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Guénebaut V, Schlitt A, Weiss H, Leonard K, Friedrich T. Consistent structure between bacterial and mitochondrial NADH:ubiquinone oxidoreductase (complex I). J Mol Biol 1998; 276:105-12. [PMID: 9514725 DOI: 10.1006/jmbi.1997.1518] [Citation(s) in RCA: 201] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Respiratory chains of bacteria and mitochondria contain closely related forms of the proton-pumping NADH:ubiquinone oxidoreductase (complex I). In bacteria the complex has a molecular mass of approximately 530 kDa and consists of 14 different subunits. The homologues of these 14 subunits together with some 27 additional subunits make up the mitochondrial complex, adding up to a molecular mass of approximately 1 MDa. We calculated three-dimensional models at medium resolution of isolated and negatively stained complex I particles from Eschericha coli and Neurospora crassa by electron microscopy using the random conical tilt reconstruction technique. Both the bacterial and the mitochondrial complexes are L-shaped molecules with an intrinsic membrane arm extending into the lipid bilayer and a peripheral arm protruding from the membrane. It is discussed whether the consistent length of the arms of both complexes has an implication for their function. The additional protein mass of the mitochondrial complex is distributed along both arms, but especially around the junction between the two arms and around the membrane arm. It appears that the structural framework of procaryotic complex I is stabilized in eucaryotes by this additional mass. A discrete location of additional protein in the peripheral arm of the mitochondrial complex is interpreted as being the possible position of two subunits with a specialized role in the biosynthesis of a yet unknown cofactor of complex I.
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Affiliation(s)
- V Guénebaut
- Structural Biology and Biocomputing Programme, European Molecular Biology Laboratory, Heidelberg, Germany
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33
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Schulte U, Abelmann A, Amling N, Brors B, Friedrich T, Kintscher L, Rasmussen T, Weiss H. Search for novel redox groups in mitochondrial NADH:ubiquinone oxidoreductase (complex I) by diode array UV/VIS spectroscopy. Biofactors 1998; 8:177-86. [PMID: 9914816 DOI: 10.1002/biof.5520080303] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The proton-translocating NADH:ubiquinone oxidoreductase of mitochondria (complex I) is a large L-shaped multisubunit complex. The peripheral matrix arm contains one FMN and a number of iron-sulfur (FeS) clusters and is involved in NADH oxidation and electron transfer to the membrane intrinsic arm. There, following a yet unknown mechanism, the redox-driven proton translocation and the ubiquinone reduction take place. Redox groups that would be able to link electron transfer with proton translocation have not been found so far in the membrane arm. We searched for such groups in complex I isolated from Neurospora crassa. Under anaerobic conditions, the preparation was analyzed in different redox states by means of UV/VIS and EPR spectroscopy. Absorption bands in the UV/VIS redox difference spectra were found which cannot be attributed to the FMN or the EPR detectable FeS clusters. The existence of two novel groups is postulated and their possible locations in the electron pathway and their roles in proton translocation are discussed.
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Affiliation(s)
- U Schulte
- Institut für Biochemie, Heinrich-Heine-Universität Düsseldorf, Germany.
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34
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Duarte M, Schulte U, Videira A. Identification of the TYKY homologous subunit of complex I from Neurospora crassa. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1322:237-41. [PMID: 9452770 DOI: 10.1016/s0005-2728(97)00084-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
A polypeptide subunit of complex I from Neurospora crassa, homologous to bovine TYKY, was expressed in Escherichia coli, purified and used for the production of rabbit antiserum. The mature mitochondrial protein displays a molecular mass of 21280 Da and results from cleavage of a presequence consisting of the first 34 N-terminal amino acids of the precursor. This protein was found closely associated with the peripheral arm of complex I.
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Affiliation(s)
- M Duarte
- Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Portugal
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35
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Yano T, Sled' VD, Ohnishi T, Yagi T. Expression and characterization of the flavoprotein subcomplex composed of 50-kDa (NQO1) and 25-kDa (NQO2) subunits of the proton-translocating NADH-quinone oxidoreductase of Paracoccus denitrificans. J Biol Chem 1996; 271:5907-13. [PMID: 8621464 DOI: 10.1074/jbc.271.10.5907] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
This study reports the expression of the flavoprotein (FP) subcomplex of the proton-translocating NADH-quinone oxidoreductase (NDH-1) from Paracoccus denitrificans, which is composed of the NQO1 (50 kDa) and the NQO2 (25 kDa) subunits. The two subunits are co-expressed in Escherichia coli using a double expression plasmid system. The expressed subunits form a water-soluble heterodimer complex with 1:1 stoichiometry. The expressed complex contained one [2Fe 2S] cluster but almost no FMN or [4Fe 4S] cluster. The two latter prosthetic groups could be partially reconstituted with FMN, Na2S, and (NH4)2Fe(SO4)2 in vitro under anaerobic conditions. The reconstituted FP subcomplex showed EPR signals from two distinct species of iron-sulfur cluster. One resonance transition originates from a [2Fe-2S] cluster with g values of gx,y,z = 1.92, 1.95, and 2.00 and slow spin relaxation, which was tentatively assigned to the cluster N1a. These EPR properties are very similar to those reported for the NQO2 subunit expressed alone (Yano, T., Sled', V. D., Ohnishi, T., and Yagi, T. (1994) Biochemistry 33, 494-499). The other originates from a [4Fe 4S] cluster with g values of gx,y, z = 1.87, 1.94, and 2.04 and fast relaxing behavior, which are reminiscent of the cluster N3 in the membrane bound enzyme complex. After reconstitution with FMN, the FP subcomplex catalyzed electron transfer from NADH and from deamino-NADH to a variety of electron acceptors. The enzymatic properties of the FP subcomplex, reconstituted with FMN and iron-sulfur, correspond to those of the isolated P. denitrificans NADH-dehydrogenase complex.
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Affiliation(s)
- T Yano
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California 92037, USA
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36
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Schneider R, Massow M, Lisowsky T, Weiss H. Different respiratory-defective phenotypes of Neurospora crassa and Saccharomyces cerevisiae after inactivation of the gene encoding the mitochondrial acyl carrier protein. Curr Genet 1995; 29:10-7. [PMID: 8595652 DOI: 10.1007/bf00313188] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The nuclear genes (acp-1, ACP1) encoding the mitochondrial acyl carrier protein were disrupted in Neurospora crassa and Saccharomyces cerevisiae. In n. crassa acp-1 is a peripheral subunit of the respiratory NADH : ubiquinone oxidoreductase (complex I). S. cerevisiae lacks complex I and its ACP1 appears to be located in the mitochondrial matrix. The loss of acp-1 in N. crassa causes two biochemical lesions. Firstly, the peripheral part of complex I is not assembled, and the membrane part is not properly assembled. The respiratory ubiquinol : cytochrome c oxidoreductase (complex III) and cytochrome c oxidase (complex IV) are made in normal amounts. Secondly, the lysophospholipid content of mitochondrial membranes is increased four-fold. In S. cerevisiae, the loss of ACP1 leads to a pleiotropic respiratory deficient phenotype.
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Affiliation(s)
- R Schneider
- Institut für Biochemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstrasse 1, D-40225 Düsseldorf, Germany
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37
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Lin TI, Sled VD, Ohnishi T, Brennicke A, Grohmann L. Analysis of the iron-sulfur clusters within the complex I (NADH:ubiquinone oxidoreductase) isolated from potato tuber mitochondria. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 230:1032-6. [PMID: 7601133 DOI: 10.1111/j.1432-1033.1995.tb20652.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The mitochondrial complex I (NADH:ubiquinone oxidoreductase) isolated from potato (Solanum tuberosum) has been investigated for the presence of iron-sulfur clusters. EPR spectroscopic analysis detected signals arising from clusters N1, N2, N3 and N4. Quantitation of the content of iron and sulfur within the isolated complex I showed the preparation to contain 22.6 mol acid-labile sulfide and 30.4 mol iron/mol complex I. The iron-sulfur cluster composition of the plant complex I appears to be similar to the well-known composition found in Neurospora crassa.
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Affiliation(s)
- T I Lin
- Institut für Genbiologische Forschung, Berlin, Germany
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38
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Leif H, Sled VD, Ohnishi T, Weiss H, Friedrich T. Isolation and characterization of the proton-translocating NADH: ubiquinone oxidoreductase from Escherichia coli. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 230:538-48. [PMID: 7607227 DOI: 10.1111/j.1432-1033.1995.tb20594.x] [Citation(s) in RCA: 239] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The proton-translocating NADH:ubiquinone oxidoreductase (complex I) was isolated from Escherichia coli by chromatographic steps performed in the presence of an alkylglucoside detergent at pH 6.0. The complex is obtained in a monodisperse state with a molecular mass of approximately 550,000 Da and is composed of 14 subunits. The subunits were assigned to the 14 genes of the nuo operon, partly based on their N-terminal sequences and partly on their apparent molecular masses. The preparation contains one noncovalently bound FMN/molecule. At least two binuclear (N1b and N1c) and three tetranuclear (N2, N3 and N4) iron-sulfur clusters were detected by EPR in the preparation when reduced with NADH. Their EPR characteristics remained mostly unaltered during the isolation process. After reconstitution in phospholipid membranes, the preparation catalyses piericidin-A-sensitive electron transfer from NADH to ubiquinone-2 with Km values similar to those of complex I in cytoplasmic membranes but with only 10% of the Vmax value. The isolated complex I was cleaved into three fragments when the pH was raised from 6.0 to 7.5 and the detergent exchanged to Triton X-100. One of these fragments is a water-soluble NADH dehydrogenase fragment which is composed of three subunits bearing at least four iron-sulfur clusters (N1b, N1c, N3 and N4) that can be reduced with NADH, one of them bearing FMN. The second, amphipathic, fragment, which is presumed to connect the NADH dehydrogenase fragment with the membrane, contains four subunits and at least one EPR-detectable iron-sulfur cluster whose spectral properties are reminiscent of the eucaryotic cluster N2. The third membrane fragment is composed of seven homologues of the mitochondrially encoded subunits of the eucaryotic complex I. This subunit arrangement coincidences to some extent with the order of the genes on the nuo operon. A topological model of the E. coli complex I is proposed.
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Affiliation(s)
- H Leif
- Institut für Biochemie, Heinrich-Heine-Universität Düsseldorf, Germany
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39
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Harkness TA, Rothery RA, Weiner JH, Werner S, Azevedo JE, Videira A, Nargang FE. Disruption of the gene encoding the 78-kilodalton subunit of the peripheral arm of complex I in Neurospora crassa by repeat induced point mutation (RIP). Curr Genet 1995; 27:339-50. [PMID: 7614557 DOI: 10.1007/bf00352103] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We have used the procedure of sheltered RIP to generate mutants of the 78-kDa protein of the peripheral arm of Neurospora crassa complex I. The nuclei containing the mutations were initially isolated as one component of a heterokaryon but subsequent analysis showed that nuclei containing null alleles of the gene could be propagated as homokaryons. This demonstrates that the gene does not serve an essential function. Sequence analysis of one allele shows that 61 transition mutations were created resulting in 39 amino-acid changes including the introduction of four stop codons. Mutant strains grow at a slower rate than wild-type and exhibit a decrease in the production of conidia. Electron paramagnetic spectroscopy of mutant mitochondria suggest that they are deficient in Fe-S clusters N-1, N-3, and N-4.
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Affiliation(s)
- T A Harkness
- Department of Biological Sciences, University of Alberta, Edmonton, Canada
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40
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Structure and expression of complex I in plant mitochondria. ACTA ACUST UNITED AC 1995. [DOI: 10.1016/b978-0-444-82235-2.50036-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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41
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Schulte U, Weiss H. Generation and characterization of NADH: ubiquinone oxidoreductase mutants in Neurospora crassa. Methods Enzymol 1995; 260:3-14. [PMID: 8592454 DOI: 10.1016/0076-6879(95)60126-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- U Schulte
- Institut für Biochemie, Heinrich-Heine-Universität, Düsseldorf, Germany
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42
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Finel M, Majander AS, Tyynelä J, De Jong AM, Albracht SP, Wikström M. Isolation and characterisation of subcomplexes of the mitochondrial NADH:ubiquinone oxidoreductase (complex I). EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 226:237-42. [PMID: 7957254 DOI: 10.1111/j.1432-1033.1994.tb20046.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Enzymically active subcomplexes were purified from bovine mitochondrial NADH:ubiquinone oxidoreductase (complex I) by sucrose-gradient centrifugation in the presence of detergents. These subcomplexes, named I lambda, IS, and I lambda S, catalyse ferricyanide and ubiquinone-1 (Q-1) reduction by NADH at similar rates to complex I, but do not catalyse the reduction of decylubiquinone. In addition, the Q-1 reductase activity of all the subcomplexes is insensitive to rotenone. Chemical and EPR analyses of the subcomplexes show that FMN and all the Fe-S clusters of complex I are present, but that the line shape of cluster 2 is modified. The smallest subcomplex, I lambda S, contains only approximately 13 subunits, as compared to approximately 22 in the previously described subcomplex I alpha [Finel, M., Skehel, J. M., Albracht, S. J. P., Fearnley, I. M. & Walker, J. E. (1992) Biochemistry 31, 11425-11434], but it retains the 75-, 51-, 49-, 30-, 24-, 23- (TYKY) and 20-kDa (PSST) subunits, which are suggested to form a functional core that comprises the EPR-detectable Fe-S clusters 1-4, and FMN. The structural and functional implications of such an arrangement are discussed.
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Affiliation(s)
- M Finel
- Helsinki Bioenergetics Group, Department of Medical Chemistry, University of Helsinki, Finland
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43
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Pereira MM, Antunes AM, Nunes OC, da Costa MS, Teixeira M. A membrane-bound HIPIP type center in the thermohalophile Rhodothermus marinus. FEBS Lett 1994; 352:327-30. [PMID: 7925995 DOI: 10.1016/0014-5793(94)00985-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A HIPIP-type center was discovered in intact membranes of the thermohalophilic aerobe Rhodothermus marinus. In both the membrane-bound state and after detergent solubilization and partial purification, this center exhibits an almost axial EPR spectrum, with g-values at 2.13 and 2.03, similar to those of soluble HIPIP proteins isolated from purple bacteria. It has a high reduction potential, of 260 mV at pH 7.5. Rhodothermus HIPIP is involved in the main membrane-bound electron-transfer pathway, being reduced by NADH or succinate only in the presence of cyanide. The possible physiological function of this novel HIPIP-type center is discussed.
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Affiliation(s)
- M M Pereira
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
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44
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Azevedo JE, Eckerskorn C, Werner S. In organello assembly of respiratory-chain complex I: primary structure of the 14.8 kDa subunit of Neurospora crassa complex I. Biochem J 1994; 299 ( Pt 1):297-302. [PMID: 8166654 PMCID: PMC1138054 DOI: 10.1042/bj2990297] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A cDNA encoding the 14.8 kDa subunit of complex I from Neurospora crassa was cloned and sequenced. The deduced primary structure of this subunit reveals a predominantly hydrophilic protein containing no obvious membrane-spanning domain. In agreement with this characteristic, we have localized the 14.8 kDa subunit in the peripheral arm of the enzyme. The 14.8 kDa subunit was found to be conserved in mammalian complex I. The conservation of this subunit in such distantly related organisms suggests that the 14.8 kDa subunit is an important component of complex I. We have used an in organello system to study the biosynthetic pathway of this subunit. The 14.8 kDa polypeptide could be efficiently imported into isolated mitochondria. Furthermore, a fraction of the in-vitro-imported subunit was found to assemble in complex I. This is the first time that assembly in complex I of an in-vitro-synthesized subunit is demonstrated.
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Affiliation(s)
- J E Azevedo
- Institut für Physiologische Chemie, Universität München, Federal Republic of Germany
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45
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Azevedo JE, Videira A. Characterization of a membrane fragment of respiratory chain complex I from Neurospora crassa. Insights on the topology of the ubiquinone-binding site. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1994; 26:505-10. [PMID: 8013735 DOI: 10.1016/0020-711x(94)90007-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
1. A membrane fragment of complex I from the fungus Neurospora crassa was isolated by immunoprecipitation from alkaline-extracted mitochondrial membranes. 2. Analysis of the polypeptide composition of this hydrophobic domain of complex I has brought insights on the topology of two subunits of the enzyme, namely the 20.8 and 9.3 kDa components. 3. Our results indicate that the ubiquinone-binding site of complex I resides in the interface of the peripheral and membrane arms of the enzymes. The significance of these findings are discussed.
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Affiliation(s)
- J E Azevedo
- Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Portugal
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46
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Fecke W, Sled VD, Ohnishi T, Weiss H. Disruption of the gene encoding the NADH-binding subunit of NADH: ubiquinone oxidoreductase in Neurospora crassa. Formation of a partially assembled enzyme without FMN and the iron-sulphur cluster N-3. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 220:551-8. [PMID: 8125114 DOI: 10.1111/j.1432-1033.1994.tb18655.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
In this study, the gene of the 51-kDa NADH-binding subunit of the mitochondrial NADH:ubiquinone oxidoreductase (complex I) in Neurospora crassa was inactivated by homologous replacement with a defective gene copy. The resulting mutant, nuo51, lacks the 51-kDa subunit and shows no complex I activity but still grows at one third of the wild-type growth rate. The enzyme activity of the alternative NADH:ubiquinone oxidoreductase(s) is increased twofold while the activities of the other mitochondrial respiratory enzymes are normal. Complex I is almost completely assembled except for the NADH-binding subunit and still possesses three out of the four EPR-detectable iron-sulphur clusters. Since the deleted subunit contains the sequence motif for one tetranuclear iron-sulphur cluster, the missing cluster N-3 is considered to be bound to this subunit.
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Affiliation(s)
- W Fecke
- Institut für Biochemie, Heinrich-Heine-Universität Düsseldorf, Germany
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47
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Friedrich T, van Heek P, Leif H, Ohnishi T, Forche E, Kunze B, Jansen R, Trowitzsch-Kienast W, Höfle G, Reichenbach H. Two binding sites of inhibitors in NADH: ubiquinone oxidoreductase (complex I). Relationship of one site with the ubiquinone-binding site of bacterial glucose:ubiquinone oxidoreductase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 219:691-8. [PMID: 8307034 DOI: 10.1111/j.1432-1033.1994.tb19985.x] [Citation(s) in RCA: 217] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The effect of ten naturally occurring and two synthetic inhibitors of NADH:ubiquinone oxidoreductase (complex I) of bovine heart, Neurospora crassa and Escherichia coli and glucose:ubiquinone oxidoreductase (glucose dehydrogenase) of Gluconobacter oxidans was investigated. These inhibitors could be divided into two classes with regard to their specificity and mode of action. Class I inhibitors, including the naturally occurring piericidin A, annonin VI, phenalamid A2, aurachins A and B, thiangazole and the synthetic fenpyroximate, inhibit complex I from all three species in a partially competitive manner and glucose dehydrogenase in a competitive manner, both with regard to ubiquinone. Class II inhibitors including the naturally occurring rotenone, phenoxan, aureothin and the synthetic benzimidazole inhibit complex I from all species in an non-competitive manner, but have no effect on the glucose dehydrogenase. Myxalamid PI could not be classified as above because it inhibits only the mitochondrial complex I and in a competitive manner. All inhibitors affect the electron-transfer step from the high-potential iron-sulphur cluster to ubiquinone. Class I inhibitors appear to act directly at the ubiquinone-catalytic site which is related in complex I and glucose dehydrogenase.
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Affiliation(s)
- T Friedrich
- Institut für Biochemie, Heinrich-Heine-Universität Düsseldorf, Germany
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48
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Proton-Translocating NAD(P)-H Transhydrogenase and NADH Dehydrogenase in Photosynthetic Membranes. ACTA ACUST UNITED AC 1994. [DOI: 10.1016/s1569-2558(08)60399-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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49
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Friedrich T, Weidner U, Nehls U, Fecke W, Schneider R, Weiss H. Attempts to define distinct parts of NADH:ubiquinone oxidoreductase (complex I). J Bioenerg Biomembr 1993; 25:331-7. [PMID: 8226714 DOI: 10.1007/bf00762458] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The NADH:ubiquinone oxidoreductase (complex I) is made up of a peripheral part and a membrane part. The two parts are arranged perpendicular to each other and give the complex an unusual L-shaped structure. The peripheral part protrudes into the matrix space and constitutes the proximal segment of the electron pathway with the NADH-binding site, the FMN and at least three iron-sulfur clusters. The membrane part constitutes the distal segment of the electron pathway with at least one iron-sulfur cluster and the ubiquinone-binding site. Both parts are assembled separately and relationships of the major structural modules of the two parts with different bacterial enzymes suggest, that both parts also emerged independently in evolution. This assumption is further supported by the conserved order of bacterial complex I genes, which correlates with the topological arrangement of the corresponding subunits in the two parts of complex I.
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Affiliation(s)
- T Friedrich
- Heinrich-Heine-Universität Düsseldorf, Institut für Biochemie, Germany
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50
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Finel M. The proton-translocating NADH: ubiquinone oxidoreductase: a discussion of selected topics. J Bioenerg Biomembr 1993; 25:357-66. [PMID: 8226717 DOI: 10.1007/bf00762461] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The proton-translocating NADH:ubiquinone oxidoreductase (complex I) is a large, multi-subunit and multi-redox centre enzyme which is found in the mitochondrial inner membrane and plasma membrane of some bacteria. In this minireview an attempt has been made to critically discuss selected topics in the structure and function of this enzyme. A special emphasis is given to the iron-sulphur cluster and to the proteins that may bind them. Previous suggestions for the mechanism of proton-translocation by complex I are discussed. Subcomplexes that contain several but not all of the subunits of the intact mitochondrial enzyme are described and analysed in order to identify the functional core of the enzyme. The data on the trans-membrane organisation of several subunits is examined. It is hoped that most of the suggestions as well as the questions raised here could be experimentally tested in the near future.
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Affiliation(s)
- M Finel
- Department of Medical Chemistry, University of Helsinki, Finland
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