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Abstract
Mitochondrial diseases are a clinically heterogeneous group of disorders that ultimately result from dysfunction of the mitochondrial respiratory chain. There is some evidence to suggest that mitochondrial dysfunction plays a role in neuropsychiatric illness; however, the data are inconclusive. This article summarizes the available literature published in the area of neuropsychiatric manifestations in both children and adults with primary mitochondrial disease, with a focus on autism spectrum disorder in children and mood disorders and schizophrenia in adults.
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Affiliation(s)
- Samantha E Marin
- Department of Neurosciences, University of California, San Diego (UCSD), 9500 Gilman Drive #0935, La Jolla, CA 92093-0935, USA
| | - Russell P Saneto
- Department of Neurology, Seattle Children's Hospital, University of Washington, 4800 Sand Point Way Northeast, Seattle, WA 98105, USA; Department of Pediatrics, Seattle Children's Hospital, University of Washington, 4800 Sand Point Way Northeast, Seattle, WA 98105, USA.
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2
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Nesti C, Meschini MC, Meunier B, Sacchini M, Doccini S, Romano A, Petrillo S, Pezzini I, Seddiki N, Rubegni A, Piemonte F, Donati MA, Brasseur G, Santorelli FM. Additive effect of nuclear and mitochondrial mutations in a patient with mitochondrial encephalomyopathy. Hum Mol Genet 2015; 24:3248-56. [PMID: 25736212 DOI: 10.1093/hmg/ddv078] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 02/26/2015] [Indexed: 12/12/2022] Open
Abstract
We describe the case of a woman in whom combination of a mitochondrial (MT-CYB) and a nuclear (SDHB) mutation was associated with clinical and metabolic features suggestive of a mitochondrial disorder. The mutations impaired overall energy metabolism in the patient's muscle and fibroblasts and increased cellular susceptibility to oxidative stress. To clarify the contribution of each mutation to the phenotype, mutant yeast strains were generated. A significant defect in strains carrying the Sdh2 mutation, either alone or in combination with the cytb variant, was observed. Our data suggest that the SDHB mutation was causative of the mitochondrial disorder in our patient with a possible cumulative contribution of the MT-CYB variant. To our knowledge, this is the first association of bi-genomic variants in the mtDNA and in a nuclear gene encoding a subunit of complex II.
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Affiliation(s)
| | | | - Brigitte Meunier
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette, France
| | - Michele Sacchini
- Metabolic and Neuromuscular Unit, AOU Meyer Hospital, Florence, Italy
| | | | - Alessandro Romano
- Neuropathology Unit, Institute of Experimental Neurology and Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Sara Petrillo
- Unit for Neuromuscular and Neurodegenerative Diseases, "Bambino Gesù" Children's Hospital, Rome, Italy and
| | | | - Nadir Seddiki
- Laboratoire de Chimie Bactérienne, CNRS, 31 ch. J. Aiguier, 13402 Marseilles, France
| | - Anna Rubegni
- Molecular Medicine, IRCCS Stella Maris, Pisa, Italy
| | - Fiorella Piemonte
- Unit for Neuromuscular and Neurodegenerative Diseases, "Bambino Gesù" Children's Hospital, Rome, Italy and
| | - M Alice Donati
- Metabolic and Neuromuscular Unit, AOU Meyer Hospital, Florence, Italy
| | - Gael Brasseur
- Laboratoire de Chimie Bactérienne, CNRS, 31 ch. J. Aiguier, 13402 Marseilles, France
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3
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Meunier B, Fisher N, Ransac S, Mazat JP, Brasseur G. Respiratory complex III dysfunction in humans and the use of yeast as a model organism to study mitochondrial myopathy and associated diseases. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1827:1346-61. [PMID: 23220121 DOI: 10.1016/j.bbabio.2012.11.015] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 11/21/2012] [Accepted: 11/28/2012] [Indexed: 11/25/2022]
Abstract
The bc1 complex or complex III is a central component of the aerobic respiratory chain in prokaryotic and eukaryotic organisms. It catalyzes the oxidation of quinols and the reduction of cytochrome c, establishing a proton motive force used to synthesize adenosine triphosphate (ATP) by the F1Fo ATP synthase. In eukaryotes, the complex III is located in the inner mitochondrial membrane. The genes coding for the complex III have a dual origin. While cytochrome b is encoded by the mitochondrial genome, all the other subunits are encoded by the nuclear genome. In this review, we compile an exhaustive list of the known human mutations and associated pathologies found in the mitochondrially-encoded cytochrome b gene as well as the fewer mutations in the nuclear genes coding for the complex III structural subunits and accessory proteins such as BCS1L involved in the assembly of the complex III. Due to the inherent difficulties of studying human biopsy material associated with complex III dysfunction, we also review the work that has been conducted to study the pathologies with the easy to handle eukaryotic microorganism, the yeast Saccharomyces cerevisiae. Phenotypes, biochemical data and possible effects due to the mutations are also discussed in the context of the known three-dimensional structure of the eukaryotic complex III. This article is part of a Special Issue entitled: Respiratory complex III and related bc complexes.
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Affiliation(s)
- B Meunier
- CNRS, Centre de Génétique Moléculaire, UPR 3404, Gif-sur-Yvette, F-91198, France
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4
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Vallières C, Fisher N, Lemoine M, Pamlard O, Beaupierre S, Guillou C, Meunier B. A rapid in vivo colorimetric library screen for inhibitors of microbial respiration. ACS Chem Biol 2012; 7:1659-65. [PMID: 22762126 DOI: 10.1021/cb3002717] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A number of fungicides that target the respiratory chain enzymes complexes II and III are used in agriculture. They are active against a large range of phytopathogens. Unfortunately, the evolution of fungicide resistance has quickly become a major issue. Resistance is often caused by mutations in the inhibitor binding domains of the complexes, and new molecules are required that are able to bypass such resistance mutations. We report here on a rapid in vivo high-throughput method, using yeast and the redox dye TTC to screen chemical libraries and identify inhibitors of respiratory function. We applied that screening process, followed by a series of tests, to a diverse library of 4,640 molecules and identified a weak inhibitor of complex III without toxic effect on the cell. Interestingly, that drug (D12) is fully active against the mutant enzyme harboring the G143A mutation that confers a high level of resistance toward most of the fungicides targeting complex III but is not active against bovine complex III. Using a collection of yeast strains harboring mutations in the inhibitor binding sites (Q(o) and Q(i) sites), we showed that D12 targeted the Q(o) site and that its inhibitory activity was weakened by the mutation L275F. A phenylalanine is naturally present at position 275 in mammalian complex III, which could explain the differential sensitivity toward D12. The molecule is not structurally related to commercial inhibitors of complex III and could potentially be used as a lead compound for the development of antimicrobial agents.
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Affiliation(s)
| | - Nicholas Fisher
- Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824,
United States
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5
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Vallières C, Fisher N, Antoine T, Al-Helal M, Stocks P, Berry NG, Lawrenson AS, Ward SA, O'Neill PM, Biagini GA, Meunier B. HDQ, a potent inhibitor of Plasmodium falciparum proliferation, binds to the quinone reduction site of the cytochrome bc1 complex. Antimicrob Agents Chemother 2012; 56:3739-47. [PMID: 22547613 PMCID: PMC3393389 DOI: 10.1128/aac.00486-12] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 04/17/2012] [Indexed: 11/20/2022] Open
Abstract
The mitochondrial bc(1) complex is a multisubunit enzyme that catalyzes the transfer of electrons from ubiquinol to cytochrome c coupled to the vectorial translocation of protons across the inner mitochondrial membrane. The complex contains two distinct quinone-binding sites, the quinol oxidation site of the bc(1) complex (Q(o)) and the quinone reduction site (Q(i)), located on opposite sides of the membrane within cytochrome b. Inhibitors of the Q(o) site such as atovaquone, active against the bc(1) complex of Plasmodium falciparum, have been developed and formulated as antimalarial drugs. Unfortunately, single point mutations in the Q(o) site can rapidly render atovaquone ineffective. The development of drugs that could circumvent cross-resistance with atovaquone is needed. Here, we report on the mode of action of a potent inhibitor of P. falciparum proliferation, 1-hydroxy-2-dodecyl-4(1H)quinolone (HDQ). We show that the parasite bc(1) complex--from both control and atovaquone-resistant strains--is inhibited by submicromolar concentrations of HDQ, indicating that the two drugs have different targets within the complex. The binding site of HDQ was then determined by using a yeast model. Introduction of point mutations into the Q(i) site, namely, G33A, H204Y, M221Q, and K228M, markedly decreased HDQ inhibition. In contrast, known inhibitor resistance mutations at the Q(o) site did not cause HDQ resistance. This study, using HDQ as a proof-of-principle inhibitor, indicates that the Q(i) site of the bc(1) complex is a viable target for antimalarial drug development.
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Affiliation(s)
- Cindy Vallières
- Centre de Génétique Moléculaire, CNRS, FRC 3115, Avenue de la Terrasse, Gif-sur-Yvette, France
| | - Nicholas Fisher
- Centre for Tropical and Infectious Diseases, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Thomas Antoine
- Centre for Tropical and Infectious Diseases, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Mohammed Al-Helal
- Centre for Tropical and Infectious Diseases, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Paul Stocks
- Centre for Tropical and Infectious Diseases, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Neil G. Berry
- Department of Chemistry, University of Liverpool, Liverpool, United Kingdom
| | | | - Stephen A. Ward
- Centre for Tropical and Infectious Diseases, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Paul M. O'Neill
- Department of Chemistry, University of Liverpool, Liverpool, United Kingdom
| | - Giancarlo A. Biagini
- Centre for Tropical and Infectious Diseases, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Brigitte Meunier
- Centre de Génétique Moléculaire, CNRS, FRC 3115, Avenue de la Terrasse, Gif-sur-Yvette, France
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Shoffner J, Hyams L, Langley GN, Cossette S, Mylacraine L, Dale J, Ollis L, Kuoch S, Bennett K, Aliberti A, Hyland K. Fever plus mitochondrial disease could be risk factors for autistic regression. J Child Neurol 2010; 25:429-34. [PMID: 19773461 DOI: 10.1177/0883073809342128] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Autistic spectrum disorders encompass etiologically heterogeneous persons, with many genetic causes. A subgroup of these individuals has mitochondrial disease. Because a variety of metabolic disorders, including mitochondrial disease show regression with fever, a retrospective chart review was performed and identified 28 patients who met diagnostic criteria for autistic spectrum disorders and mitochondrial disease. Autistic regression occurred in 60.7% (17 of 28), a statistically significant increase over the general autistic spectrum disorder population (P < .0001). Of the 17 individuals with autistic regression, 70.6% (12 of 17) regressed with fever and 29.4% (5 of 17) regressed without identifiable linkage to fever or vaccinations. None showed regression with vaccination unless a febrile response was present. Although the study is small, a subgroup of patients with mitochondrial disease may be at risk of autistic regression with fever. Although recommended vaccinations schedules are appropriate in mitochondrial disease, fever management appears important for decreasing regression risk.
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Affiliation(s)
- John Shoffner
- Medical Neurogenetics, LLC, Atlanta, Georgia 30338, USA.
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7
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Mutations in cytochrome b that affect kinetics of the electron transfer reactions at center N in the yeast cytochrome bc1 complex. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:239-49. [DOI: 10.1016/j.bbabio.2007.08.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2007] [Revised: 08/15/2007] [Accepted: 08/17/2007] [Indexed: 11/24/2022]
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Seddiki N, Meunier B, Lemesle-Meunier D, Brasseur G. Is Cytochrome b Glutamic Acid 272 a Quinol Binding Residue in the bc1 Complex of Saccharomyces cerevisiae? Biochemistry 2008; 47:2357-68. [DOI: 10.1021/bi701905a] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Nadir Seddiki
- Laboratoire de Bioénergétique et Ingénierie des Protéines, CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille cedex 20, France, and Centre de Génétique Moléculaire, CNRS, UPR 2167, Gif-sur-Yvette, F-91198, France
| | - Brigitte Meunier
- Laboratoire de Bioénergétique et Ingénierie des Protéines, CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille cedex 20, France, and Centre de Génétique Moléculaire, CNRS, UPR 2167, Gif-sur-Yvette, F-91198, France
| | - Danielle Lemesle-Meunier
- Laboratoire de Bioénergétique et Ingénierie des Protéines, CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille cedex 20, France, and Centre de Génétique Moléculaire, CNRS, UPR 2167, Gif-sur-Yvette, F-91198, France
| | - Gaël Brasseur
- Laboratoire de Bioénergétique et Ingénierie des Protéines, CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille cedex 20, France, and Centre de Génétique Moléculaire, CNRS, UPR 2167, Gif-sur-Yvette, F-91198, France
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Lemaire C, Dujardin G. Preparation of respiratory chain complexes from Saccharomyces cerevisiae wild-type and mutant mitochondria : activity measurement and subunit composition analysis. Methods Mol Biol 2008; 432:65-81. [PMID: 18370011 DOI: 10.1007/978-1-59745-028-7_5] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The mitochondrial oxidative phosphorylation involves five multimeric complexes imbedded in the inner membrane: complex I (Nicotinamide Adenine Dinucleotide (NADH) quinone oxidoreductase), II (succinate dehydrogenase), III (ubiquinol cytochrome c oxido reductase or bc1 complex), IV (cytochrome c oxidase), and V (ATP synthase). These respiratory complexes are conserved from the yeast Saccharomyces cerevisiae to human with the exception of complex I, which is replaced by three NADH dehydrogenases in S. cerevisiae. Here, we provide several protocols allowing an exhaustive characterization of each yeast complex: this chapter describes procedures from mitochondria preparation to measurement of the activity of each complex and analysis of their subunit composition and provides information on the interactions between different complexes.
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Affiliation(s)
- Claire Lemaire
- CNRS, Centre de Génétique Moléculaire, Gif sur Yvette, France
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10
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Rotsaert FAJ, Ding MG, Trumpower BL. Differential efficacy of inhibition of mitochondrial and bacterial cytochrome bc1 complexes by center N inhibitors antimycin, ilicicolin H and funiculosin. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2007; 1777:211-9. [PMID: 18022381 DOI: 10.1016/j.bbabio.2007.10.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2007] [Revised: 10/16/2007] [Accepted: 10/17/2007] [Indexed: 10/22/2022]
Abstract
We have compared the efficacy of inhibition of the cytochrome bc1 complexes from yeast and bovine heart mitochondria and Paracoccus denitrificans by antimycin, ilicicolin H, and funiculosin, three inhibitors that act at the quinone reduction site at center N of the enzyme. Although the three inhibitors have some structural features in common, they differ significantly in their patterns of inhibition. Also, while the overall folding pattern of cytochrome b around center N is similar in the enzymes from the three species, amino acid sequence differences create sufficient structural differences so that there are striking differences in the inhibitors binding to the three enzymes. Antimycin is the most tightly bound of the three inhibitors, and binds stoichiometrically to the isolated enzymes from all three species under the cytochrome c reductase assay conditions. Ilicicolin H also binds stoichiometrically to the yeast enzyme, but binds approximately 2 orders of magnitude less tightly to the bovine enzyme and is essentially non-inhibitory to the Paracoccus enzyme. Funiculosin on the other hand inhibits the yeast and bovine enzymes similarly, with IC50 approximately 10 nM, while the IC50 for the Paracoccus enzyme is more than 10-fold higher. Similar differences in inhibitor efficacy were noted in bc1 complexes from yeast mutants with single amino acid substitutions at the center N site, although the binding affinity of quinone and quinol substrates were not perturbed to a degree that impaired catalytic function in the variant enzymes. These results reveal a high degree of specificity in the determinants of ligand-binding at center N, accompanied by sufficient structural plasticity for substrate binding as to not compromise center N function. The results also demonstrate that, in principle, it should be possible to design novel inhibitors targeted toward center N of the bc1 complex with appropriate species selectivity to allow their use as drugs against pathogenic fungi and parasites.
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Lemaire C, Guibet-Grandmougin F, Angles D, Dujardin G, Bonnefoy N. A yeast mitochondrial membrane methyltransferase-like protein can compensate for oxa1 mutations. J Biol Chem 2004; 279:47464-72. [PMID: 15355998 DOI: 10.1074/jbc.m404861200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Members of the Oxa1p/Alb3/YidC family mediate the insertion of various organelle or bacterial hydrophobic proteins into membranes. They present at least five transmembrane segments (TM) linked by hydrophilic domains located on both sides of the membrane. To examine how Oxa1p structure relates to its function, we have introduced point mutations and large deletions into various domains of the yeast mitochondrial protein. These mutants allowed us to show the importance of the first TM domain as well as a synergistic interaction between the first loop and the C-terminal tail, which both protrude into the matrix. These mutants also led to the isolation of a high copy suppressor, OMS1, which encodes a member of the methyltransferase family. Overexpression of OMS1 seems to increase the steady-state level of both the mutant and wild-type Oxa1p. We show that Oms1p is a mitochondrial inner membrane protein inserted independently of Oxa1p. Oms1p presents one TM and a N-in C-out topology with the C-terminal domain carrying the methyltransferase-like domain. A conserved motif within this domain is essential for the suppression of oxa1 mutations. We discuss the possible role of Oms1p on Oxa1p intermembrane space domain.
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Affiliation(s)
- Claire Lemaire
- Centre de Génétique Moléculaire, CNRS Gif-sur-Yvette, UPR 2167, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France
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12
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Brasseur G, Lemesle-Meunier D, Reinaud F, Meunier B. QO Site Deficiency Can Be Compensated by Extragenic Mutations in the Hinge Region of the Iron-Sulfur Protein in the bc1 Complex of Saccharomyces cerevisiae. J Biol Chem 2004; 279:24203-11. [PMID: 15039445 DOI: 10.1074/jbc.m311576200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mitochondrial bc(1) complex catalyzes the oxidation of ubiquinol and the reduction of cytochrome (cyt) c. The cyt b mutation A144F has been introduced in yeast by the biolistic method. This residue is located in the cyt b cd(1) amphipathic helix in the quinol-oxidizing (Q(O)) site. The resulting mutant was respiration-deficient and was affected in the quinol binding and electron transfer rates at the Q(O) site. An intragenic suppressor mutation was selected (A144F+F179L) that partially alleviated the defect of quinol oxidation of the original mutant A144F. The suppressor mutation F179L, located at less than 4 A from A144F, is likely to compensate directly the steric hindrance caused by phenylalanine at position 144. A second set of suppressor mutations was obtained, which also partially restored the quinol oxidation activity of the bc(1) complex. They were located about 20 A from A144F in the hinge region of the iron-sulfur protein (ISP) between residues 85 and 92. This flexible region is crucial for the movement of the ISP between cyt b and cyt c(1) during enzyme turnover. Our results suggested that the compensatory effect of the mutations in ISP was due to the repositioning of this subunit on cyt b during quinol oxidation. This genetic and biochemical study thus revealed the close interaction between the cyt b cd(1) helix in the quinol-oxidizing Q(O) site and the ISP via the flexible hinge region and that fine-tuning of the Q(O) site catalysis can be achieved by subtle changes in the linker domain of the ISP.
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Affiliation(s)
- Gaël Brasseur
- Laboratoire de Bioénergétique et Ingénierie des Protéines, CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
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Gao X, Wen X, Esser L, Quinn B, Yu L, Yu CA, Xia D. Structural basis for the quinone reduction in the bc1 complex: a comparative analysis of crystal structures of mitochondrial cytochrome bc1 with bound substrate and inhibitors at the Qi site. Biochemistry 2003; 42:9067-80. [PMID: 12885240 DOI: 10.1021/bi0341814] [Citation(s) in RCA: 186] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cytochrome bc(1) is an integral membrane protein complex essential to cellular respiration and photosynthesis. The Q cycle reaction mechanism of bc(1) postulates a separated quinone reduction (Q(i)) and quinol oxidation (Q(o)) site. In a complete catalytic cycle, a quinone molecule at the Q(i) site receives two electrons from the b(H) heme and two protons from the negative side of the membrane; this process is specifically inhibited by antimycin A and NQNO. The structures of bovine mitochondrial bc(1) in the presence or absence of bound substrate ubiquinone and with either the bound antimycin A(1) or NQNO were determined and refined. A ubiquinone with its first two isoprenoid repeats and an antimycin A(1) were identified in the Q(i) pocket of the substrate and inhibitor bound structures, respectively; the NQNO, on the other hand, was identified in both Q(i) and Q(o) pockets in the inhibitor complex. The two inhibitors occupied different portions of the Q(i) pocket and competed with substrate for binding. In the Q(o) pocket, the NQNO behaves similarly to stigmatellin, inducing an iron-sulfur protein conformational arrest. Extensive binding interactions and conformational adjustments of residues lining the Q(i) pocket provide a structural basis for the high affinity binding of antimycin A and for phenotypes of inhibitor resistance. A two-water-mediated ubiquinone protonation mechanism is proposed involving three Q(i) site residues His(201), Lys(227), and Asp(228).
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Affiliation(s)
- Xiugong Gao
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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14
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Saint-Georges Y, Bonnefoy N, di Rago JP, Chiron S, Dujardin G. A pathogenic cytochrome b mutation reveals new interactions between subunits of the mitochondrial bc1 complex. J Biol Chem 2002; 277:49397-402. [PMID: 12384503 DOI: 10.1074/jbc.m207219200] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Energy transduction in mitochondria involves five oligomeric complexes embedded within the inner membrane. They are composed of catalytic and noncatalytic subunits, the role of these latter proteins often being difficult to assign. One of these complexes, the bc1 complex, is composed of three catalytic subunits including cytochrome b and seven or eight noncatalytic subunits. Recently, several mutations in the human cytochrome b gene have been linked to various diseases. We have studied in detail the effects of a cardiomyopathy generating mutation G252D in yeast. This mutation disturbs the biogenesis of the bc1 complex at 36 degrees C and decreases the steady-state level of the noncatalytic subunit Qcr9p. In addition, the G252D mutation and the deletion of QCR9 show synergetic defects that can be partially bypassed by suppressor mutations at position 252 and by a new cytochrome b mutation, P174T. Altogether, our results suggest that the supernumerary subunit Qcr9p enhances or stabilizes the interactions between the catalytic subunits, this role being essential at high temperature.
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Affiliation(s)
- Yann Saint-Georges
- Centre de Génétique Moléculaire du CNRS, Avenue de la Terrasse, 91198-Gif sur Yvette, France
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15
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Saint-Georges Y, Hamel P, Lemaire C, Dujardin G. Role of positively charged transmembrane segments in the insertion and assembly of mitochondrial inner-membrane proteins. Proc Natl Acad Sci U S A 2001; 98:13814-9. [PMID: 11717439 PMCID: PMC61124 DOI: 10.1073/pnas.251503098] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2001] [Indexed: 11/18/2022] Open
Abstract
The biogenesis of membrane oligomeric complexes is an intricate process that requires the insertion and assembly of transmembrane (TM) domains into the lipid bilayer. The Oxa1p family plays a key role in this process in organelles and bacteria. Hell et al. (2001, EMBO J., 20, 1281-1288) recently have proposed that Oxa1p could act as part of a general membrane insertion machinery for mitochondrial respiratory complex subunits. We have previously shown that mutations in the TM domain of Cyt1p can partially compensate for the absence of Oxa1p. Here, we demonstrate that a single amino acid substitution in the TM domain of Qcr9p can bypass Oxa1p in yeast. Qcr9p and Cyt1p are two subunits of the respiratory complex bc1 and their relative roles in the assembly of other respiratory complexes have been investigated. The mutations we have isolated in Cyt1p or Qcr9p introduce positively charged amino acids, and we show that the mutant TM domain of Cyt1p mediates the restoration of complex assembly. We propose that the positive charges introduced in Cyt1p and Qcr9p TM domains promote interactions with negatively charged TM domains of other respiratory complex subunits, allowing the coinsertion of both domains into the membrane, in the absence of Oxa1p. This model argues in favor of a role of Oxa1p in the insertion and the lateral exit of less hydrophobic TM domains from the translocation site into the lipid bilayer.
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Affiliation(s)
- Y Saint-Georges
- Centre de Génétique Moléculaire du Centre National de la Recherche Scientifique, Avenue de la Terrasse, 91198-Gif sur Yvette, France
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16
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Brasseur G, Di Rago JP, Slonimski PP, Lemesle-Meunier D. Analysis of suppressor mutation reveals long distance interactions in the bc(1) complex of Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1506:89-102. [PMID: 11522251 DOI: 10.1016/s0005-2728(01)00186-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Four totally conserved glycines are involved in the packing of the two cytochrome b hemes, b(L) and b(H), of the bc(1) complex. The conserved glycine 131 is involved in the packing of heme b(L) and is separated by only 3 A from this heme in the bc(1) complex structure. The cytochrome b respiratory deficient mutant G131S is affected in the assembly of the bc(1) complex. An intragenic suppressor mutation was obtained at position 260, in the ef loop, where a glycine was replaced by an alanine. This respiratory competent revertant exhibited a low bc(1) complex activity and was affected in the electron transfer at the Q(P) site. The k(min) for the substrate DBH(2) was diminished by an order of magnitude and EPR spectra showed a partially empty Q(P) site. However, the binding of the Q(P) site inhibitors stigmatellin and myxothiazol remained unchanged in the suppressor strain. Optical spectroscopy revealed that heme b(L) is red shifted by 0.8 nm and that the E(m) of heme b(L) was slightly increased (+20 mV) in the revertant strain as compared to wild type strain values. Addition of a methyl group at position 260 is thus sufficient to allow the assembly of the bc(1) complex and the insertion of heme b(L) despite the presence of the serine at position 131. Surprisingly, reversion at position 260 was located 13 A away from the original mutation and revealed a long distance interaction in the yeast bc(1) complex.
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Affiliation(s)
- G Brasseur
- Laboratoire de Bioénergétique et Ingénierie des Protéines, CNRS, Marseilles, France.
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Fisher N, Meunier B. Effects of mutations in mitochondrial cytochrome b in yeast and man. Deficiency, compensation and disease. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:1155-62. [PMID: 11231266 DOI: 10.1046/j.1432-1327.2001.02010.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The mitochondrial cytochrome bc(1) complex is a key protonmotive component of eukaryotic respiratory chains. The mitochondrially encoded cytochrome b forms, with cytochrome c(1) and the iron--sulfur protein, the catalytic core of this multimeric enzyme. Mutations of cytochrome b have been reported in association with human diseases. In the highly homologous yeast cytochrome b, several mutations that impair the respiratory function, and reversions that correct the defect, have been described. In this paper, we re-examine the mutations in the light of the atomic structure of the complex, and discuss the possible effect, at enzyme level, of the human cytochrome b mutations and the correcting effect of the reversions.
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Affiliation(s)
- N Fisher
- Department of Biology, University College London, UK
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Cardazzo B, Hamel P, Sakamoto W, Wintz H, Dujardin G. Isolation of an Arabidopsis thaliana cDNA by complementation of a yeast abc1 deletion mutant deficient in complex III respiratory activity. Gene 1998; 221:117-25. [PMID: 9852956 DOI: 10.1016/s0378-1119(98)00417-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The yeast Abc1 protein acts as a chaperone-like protein essential for the proper conformation and efficient functioning of the respiratory complex III. By functional complementation of a yeast abc1 mutant, we have identified an Arabidopsis thaliana cDNA that corresponds to a single copy gene and encodes a protein sharing 45% similarity with the yeast Abc1p protein. Cytochrome spectra and respiratory activity measurements have shown that the plant protein allows a partial restoration of the complex III activity. No major difference in the steady-state level of ABC1At mRNA was observed in various plant tissues, suggesting that ABC1At is constitutively expressed in A. thaliana. Phylogenetic analysis revealed that the Abc1At protein belongs to a large family of proteins composed of two eukaryotic and one prokaryotic subgroups differing by their degree of similarity and probably by their function.
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Affiliation(s)
- B Cardazzo
- Centre de Génétique Moléculaire, Gif sur Yvette, France
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Hamel P, Lemaire C, Bonnefoy N, Brivet-Chevillotte P, Dujardin G. Mutations in the membrane anchor of yeast cytochrome c1 compensate for the absence of Oxa1p and generate carbonate-extractable forms of cytochrome c1. Genetics 1998; 150:601-11. [PMID: 9755193 PMCID: PMC1460358 DOI: 10.1093/genetics/150.2.601] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Oxa1p is a mitochondrial inner membrane protein that is mainly required for the insertion/assembly of complex IV and ATP synthase and is functionally conserved in yeasts, humans, and plants. We have isolated several independent suppressors that compensate for the absence of Oxa1p. Molecular cloning and sequencing reveal that the suppressor mutations (CYT1-1 to -6) correspond to amino acid substitutions that are all located in the membrane anchor of cytochrome c1 and decrease the hydrophobicity of this anchor. Cytochrome c1 is a catalytic subunit of complex III, but the CYT1-1 mutation does not seem to affect the electron transfer activity. The double-mutant cyt1-1,164, which has a drastically reduced electron transfer activity, still retains the suppressor activity. Altogether, these results suggest that the suppressor function of cytochrome c1 is independent of its electron transfer activity. In addition to the membrane-bound cytochrome c1, carbonate-extractable forms accumulate in all the suppressor strains. We propose that these carbonate-extractable forms of cytochrome c1 are responsible for the suppressor function by preventing the degradation of the respiratory complex subunits that occur in the absence of Oxa1p.
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Affiliation(s)
- P Hamel
- Centre de Génétique Moléculaire du Centre National de la Recherche Scientifique, 91198 Gif-sur-Yvette Cedex, France
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Brasseur G, Tron G, Dujardin G, Slonimski PP, Brivet-Chevillotte P. The nuclear ABC1 gene is essential for the correct conformation and functioning of the cytochrome bc1 complex and the neighbouring complexes II and IV in the mitochondrial respiratory chain. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 246:103-11. [PMID: 9210471 DOI: 10.1111/j.1432-1033.1997.t01-1-00103.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The nuclear ABC1 gene was isolated as a multicopy suppressor of a cytochrome b mRNA translation defect. Its inactivation leads to a respiratory deficiency suggesting a block in the bc1 segment of the respiratory chain [Bousquet, I., Dujardin, G. & Slonimski, P. P. (1991) EMBO J. 10, 2023-2031]. In the present study, we established that deleting the ABC1 chromosomal gene from Saccharomyces cerevisiae does not prevent the assembly of the bc1 complex (complex III) but markedly impairs the kinetics of its high-potential electron transfer pathway occurring on the positive, outer, side of the membrane, which results in reduced activity of the bc1 complex. In addition, the activity of complex II and its cytochrome b560 decrease drastically and complex IV activity is halved. It is also observed that the binding of the quinol to the bc1 complex ubiquinol oxidation site is affected and that adding exogenous quinones partially compensates for the respiratory deficiency in vitro, although the quinone content of mutant and wild-type mitochondria are similar. Lastly, complexes II, III and IV are found to be thermosensitive and the bc1 complex exhibits greater sensitivity than the wild-type strain to center N and P inhibitors, suggesting that the three multisubunit complexes have undergone structural modifications. The data suggest that the ABC1 gene product acts as a chaperone-like protein essential for the proper conformation and efficient functioning of the bc1 complex and the effects of the Abc1 protein on the complexes II and IV might result from interactions with the modified bc1 complex.
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Affiliation(s)
- G Brasseur
- Laboratoire de Bioénergetique et Ingéniérie des protéines, UPR9036,Institut de Biologie Structurale et Microbiologie, CNRS, Marseille, France
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Brasseur G, Saribaş AS, Daldal F. A compilation of mutations located in the cytochrome b subunit of the bacterial and mitochondrial bc1 complex. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1275:61-9. [PMID: 8688453 DOI: 10.1016/0005-2728(96)00051-5] [Citation(s) in RCA: 139] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
In anticipation of the structure of the bc1 complex which is now imminent, we present here a preliminary compilation of all available cytochrome b mutants that have been isolated or constructed to date both in prokaryotic and eukaryotic species. We have briefly summarized their salient properties with respect to the structure and function of cytochrome b and to the Qo and Qi sites of the bc1 complex. In conjunction with the high resolution structure of the bc1 complex, this database is expected to serve as a useful reference point for the available data and help to focus and stimulate future experimental work in this field.
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Affiliation(s)
- G Brasseur
- Department of Biology, University of Pennsylvania, Philadelphia 19104, USA.
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