151
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Seelert H, Dani DN, Dante S, Hauss T, Krause F, Schäfer E, Frenzel M, Poetsch A, Rexroth S, Schwassmann HJ, Suhai T, Vonck J, Dencher NA. From protons to OXPHOS supercomplexes and Alzheimer's disease: structure-dynamics-function relationships of energy-transducing membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:657-71. [PMID: 19281792 DOI: 10.1016/j.bbabio.2009.02.028] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Revised: 02/20/2009] [Accepted: 02/20/2009] [Indexed: 11/29/2022]
Abstract
By the elucidation of high-resolution structures the view of the bioenergetic processes has become more precise. But in the face of these fundamental advances, many problems are still unresolved. We have examined a variety of aspects of energy-transducing membranes from large protein complexes down to the level of protons and functional relevant picosecond protein dynamics. Based on the central role of the ATP synthase for supplying the biological fuel ATP, one main emphasis was put on this protein complex from both chloroplast and mitochondria. In particular the stoichiometry of protons required for the synthesis of one ATP molecule and the supramolecular organisation of ATP synthases were examined. Since formation of supercomplexes also concerns other complexes of the respiratory chain, our work was directed to unravel this kind of organisation, e.g. of the OXPHOS supercomplex I(1)III(2)IV(1), in terms of structure and function. Not only the large protein complexes or supercomplexes work as key players for biological energy conversion, but also small components as quinones which facilitate the transfer of electrons and protons. Therefore, their location in the membrane profile was determined by neutron diffraction. Physico-chemical features of the path of protons from the generators of the electrochemical gradient to the ATP synthase, as well as of their interaction with the membrane surface, could be elucidated by time-resolved absorption spectroscopy in combination with optical pH indicators. Diseases such as Alzheimer's dementia (AD) are triggered by perturbation of membranes and bioenergetics as demonstrated by our neutron scattering studies.
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Affiliation(s)
- H Seelert
- Department of Chemistry, Technische Universität Darmstadt, Petersenstrasse 22, D-64287 Darmstadt, Germany.
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Acín-Pérez R, Fernández-Silva P, Peleato ML, Pérez-Martos A, Enriquez JA. Respiratory active mitochondrial supercomplexes. Mol Cell 2009; 32:529-39. [PMID: 19026783 DOI: 10.1016/j.molcel.2008.10.021] [Citation(s) in RCA: 601] [Impact Index Per Article: 40.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Revised: 06/19/2008] [Accepted: 10/29/2008] [Indexed: 12/16/2022]
Abstract
The structural organization of the mitochondrial respiratory complexes as four big independently moving entities connected by the mobile carriers CoQ and cytochrome c has been challenged recently. Blue native gel electrophoresis reveals the presence of high-molecular-weight bands containing several respiratory complexes and suggesting an in vivo assembly status of these structures (respirasomes). However, no functional evidence of the activity of supercomplexes as true respirasomes has been provided yet. We have observed that (1) supercomplexes are not formed when one of their component complexes is absent; (2) there is a temporal gap between the formation of the individual complexes and that of the supercomplexes; (3) some putative respirasomes contain CoQ and cytochrome c; (4) isolated respirasomes can transfer electrons from NADH to O(2), that is, they respire. Therefore, we have demonstrated the existence of a functional respirasome and propose a structural organization model that accommodates these findings.
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Affiliation(s)
- Rebeca Acín-Pérez
- Departamento de Bioquimica, Universidad de Zaragoza, Miguel Servet, 177, 50013 Zaragoza, Spain
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153
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Starkov AA. The role of mitochondria in reactive oxygen species metabolism and signaling. Ann N Y Acad Sci 2009; 1147:37-52. [PMID: 19076429 DOI: 10.1196/annals.1427.015] [Citation(s) in RCA: 564] [Impact Index Per Article: 37.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Oxidative stress is considered a major contributor to the etiology of both "normal" senescence and severe pathologies with serious public health implications. Several cellular sources, including mitochondria, are known to produce significant amounts of reactive oxygen species (ROS) that may contribute to intracellular oxidative stress. Mitochondria possess at least 10 known sites that are capable of generating ROS, but they also feature a sophisticated multilayered ROS defense system that is much less studied. This review summarizes the current knowledge about major components involved in mitochondrial ROS metabolism and factors that regulate ROS generation and removal at the level of mitochondria. An integrative systemic approach is applied to analysis of mitochondrial ROS metabolism, which is "dissected" into ROS generation, ROS emission, and ROS scavenging. The in vitro ROS-producing capacity of several mitochondrial sites is compared in the metabolic context and the role of mitochondria in ROS-dependent intracellular signaling is discussed.
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154
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Abstract
The phrase "respiratory chain" implies that energy that is ultimately derived from mitochondrial oxidative phosphorylation is produced via a linear arrangement of discrete electron transfer complexes. A recent paper in Molecular Cell (Acin-Pérez et al., 2008) calls this model into question.
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155
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Braun H, Sunderhaus S, Boekema EJ, Kouřil R. Chapter 10 Purification of the Cytochrome c Reductase/Cytochrome c Oxidase Super Complex of Yeast Mitochondria. Methods Enzymol 2009; 456:183-90. [DOI: 10.1016/s0076-6879(08)04410-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
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156
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Lavergne J, Verméglio A, Joliot P. Functional Coupling Between Reaction Centers and Cytochrome bc 1 Complexes. THE PURPLE PHOTOTROPHIC BACTERIA 2009. [DOI: 10.1007/978-1-4020-8815-5_26] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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157
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158
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Suthammarak W, Yang YY, Morgan PG, Sedensky MM. Complex I function is defective in complex IV-deficient Caenorhabditis elegans. J Biol Chem 2008; 284:6425-35. [PMID: 19074434 DOI: 10.1074/jbc.m805733200] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Cytochrome c oxidase (COX) is hypothesized to be an important regulator of oxidative phosphorylation. However, no animal phenotypes have been described due to genetic defects in nuclear-encoded subunits of COX. We knocked down predicted homologues of COX IV and COX Va in the nematode Caenorhabditis elegans. Animals treated with W09C5.8 (COX IV) or Y37D8A.14 (COX Va) RNA interference had shortened lifespans and severe defects in mitochondrial respiratory chain function. Amount and activity of complex IV, as well as supercomplexes that included complex IV, were decreased in COX-deficient worms. The formation of supercomplex I:III was not dependent on COX. We found that COX deficiencies decreased intrinsic complex I enzymatic activity, as well as complex I-III enzymatic activity. However, overall amounts of complex I were not decreased in these animals. Surprisingly, intrinsic complex I enzymatic activity is dependent on the presence of complex IV, despite no overall decrease in the amount of complex I. Presumably the association of complex I with complex IV within the supercomplex I:III:IV enhances electron flow through complex I. Our results indicate that reduction of a single subunit within the electron transport chain can affect multiple enzymatic steps of electron transfer, including movement within a different protein complex. Patients presenting with multiple defects of electron transport may, in fact, harbor a single genetic defect.
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Affiliation(s)
- Wichit Suthammarak
- Department of Genetics, Case Western Reserve University, and Department of Anesthesiology, University Hospital, Cleveland, OH, USA
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159
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The higher level of organization of the oxidative phosphorylation system: mitochondrial supercomplexes. J Bioenerg Biomembr 2008; 40:419-24. [PMID: 18839290 PMCID: PMC2780661 DOI: 10.1007/s10863-008-9167-5] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2008] [Accepted: 07/20/2008] [Indexed: 01/13/2023]
Abstract
The organization of the oxidative phosphorylation (OXPHOS) system within the inner mitochondrial membrane appears to be far more complicated than previously thought. In particular, the individual protein complexes of the OXPHOS system (complexes I to V) were found to specifically interact forming defined supramolecular structures. Blue-native polyacrylamide gel electrophoresis and single particle electron microscopy proved to be especially valuable in studying the so-called "respiratory supercomplexes". Based on these procedures, increasing evidence was presented supporting a "solid state" organization of the OXPHOS system. Here, we summarize results on the formation, organisation and function of the various types of mitochondrial OXPHOS supercomplexes.
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160
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Sarewicz M, Borek A, Daldal F, Froncisz W, Osyczka A. Demonstration of short-lived complexes of cytochrome c with cytochrome bc1 by EPR spectroscopy: implications for the mechanism of interprotein electron transfer. J Biol Chem 2008; 283:24826-36. [PMID: 18617515 PMCID: PMC2529009 DOI: 10.1074/jbc.m802174200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2008] [Revised: 07/08/2008] [Indexed: 11/18/2022] Open
Abstract
One of the steps of a common pathway for biological energy conversion involves electron transfer between cytochrome c and cytochrome bc1. To clarify the mechanism of this reaction, we examined the structural association of those two proteins using the electron transfer-independent electron paramagnetic resonance (EPR) techniques. Drawing on the differences in the continuous wave EPR spectra and saturation recoveries of spin-labeled bacterial and mitochondrial cytochromes c recorded in the absence and presence of bacterial cytochrome bc1, we have exposed a time scale of dynamic equilibrium between the bound and the free state of cytochrome c at various ionic strengths. Our data show a successive decrease of the bound cytochrome c fraction as the ionic strength increases, with a limit of approximately 120 mm NaCl above which essentially no bound cytochrome c can be detected by EPR. This limit does not apply to all of the interactions of cytochrome c with cytochrome bc1 because the cytochrome bc1 enzymatic activity remained high over a much wider range of ionic strengths. We concluded that EPR monitors just the tightly bound state of the association and that an averaged lifetime of this state decreases from over 100 micros at low ionic strength to less than 400 ns at an ionic strength above 120 mm. This suggests that at physiological ionic strength, the tightly bound complex on average lasts less than the time needed for a single electron exchange between hemes c and c1, indicating that productive electron transfer requires several collisions of the two molecules. This is consistent with an early idea of diffusion-coupled reactions that link the soluble electron carriers with the membranous complexes, which, we believe, provides a robust means of regulating electron flow through these complexes.
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Affiliation(s)
- Marcin Sarewicz
- Department of Biophysics, Faculty of
Biochemistry, Biophysics, and Biotechnology, Jagiellonian University, 30-387
Kraków, Poland and the Department of
Biology, Plant Science Institute, University of Pennsylvania, Philadelphia,
Pennsylvania 19104
| | - Arkadiusz Borek
- Department of Biophysics, Faculty of
Biochemistry, Biophysics, and Biotechnology, Jagiellonian University, 30-387
Kraków, Poland and the Department of
Biology, Plant Science Institute, University of Pennsylvania, Philadelphia,
Pennsylvania 19104
| | - Fevzi Daldal
- Department of Biophysics, Faculty of
Biochemistry, Biophysics, and Biotechnology, Jagiellonian University, 30-387
Kraków, Poland and the Department of
Biology, Plant Science Institute, University of Pennsylvania, Philadelphia,
Pennsylvania 19104
| | - Wojciech Froncisz
- Department of Biophysics, Faculty of
Biochemistry, Biophysics, and Biotechnology, Jagiellonian University, 30-387
Kraków, Poland and the Department of
Biology, Plant Science Institute, University of Pennsylvania, Philadelphia,
Pennsylvania 19104
| | - Artur Osyczka
- Department of Biophysics, Faculty of
Biochemistry, Biophysics, and Biotechnology, Jagiellonian University, 30-387
Kraków, Poland and the Department of
Biology, Plant Science Institute, University of Pennsylvania, Philadelphia,
Pennsylvania 19104
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161
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Garcia-Palmer FJ. Lack of functional assembly in mitochondrial supercomplexes: a new insight into impaired mitochondrial function? Cardiovasc Res 2008; 80:3-4. [DOI: 10.1093/cvr/cvn213] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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162
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Genova M, Baracca A, Biondi A, Casalena G, Faccioli M, Falasca A, Formiggini G, Sgarbi G, Solaini G, Lenaz G. Is supercomplex organization of the respiratory chain required for optimal electron transfer activity? BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:740-6. [DOI: 10.1016/j.bbabio.2008.04.007] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2007] [Revised: 03/31/2008] [Accepted: 04/05/2008] [Indexed: 02/03/2023]
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163
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Pathak RU, Davey GP. Complex I and energy thresholds in the brain. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:777-82. [DOI: 10.1016/j.bbabio.2008.05.443] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Revised: 05/21/2008] [Accepted: 05/22/2008] [Indexed: 10/22/2022]
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164
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Vonck J, Schäfer E. Supramolecular organization of protein complexes in the mitochondrial inner membrane. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1793:117-24. [PMID: 18573282 DOI: 10.1016/j.bbamcr.2008.05.019] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2008] [Revised: 05/21/2008] [Accepted: 05/23/2008] [Indexed: 12/29/2022]
Abstract
The liquid state model that envisions respiratory chain complexes diffusing freely in the membrane is increasingly challenged by reports of supramolecular organization of the complexes in the mitochondrial inner membrane. Supercomplexes of complex III with complex I and/or IV can be isolated after solubilisation with mild detergents like digitonin. Electron microscopic studies have shown that these have a distinct architecture and are not random aggregates. A 3D reconstruction of a I1III2IV1 supercomplex shows that the ubiquinone and cytochrome c binding sites of the individual complexes are facing each other, suggesting a role in substrate channelling. Formation of supercomplexes plays a role in the assembly and stability of the complexes, suggesting that the supercomplexes are the functional state of the respiratory chain. Furthermore, a supramolecular organisation of ATP synthases has been observed in mitochondria, where ATP synthase is organised in dimer rows. Dimers can be isolated by mild detergent extraction and recent electron microscopic studies have shown that the membrane domains of the two partners in the dimer are at an angle to each other, indicating that in vivo the dimers would cause the membrane to bend. The suggested role in crista formation is supported by the observation of rows of ATP synthase dimers in the most curved parts of the cristae. Together these observations show that the mitochondrial inner membrane is highly organised and that the molecular events leading to ATP synthesis are carefully coordinated.
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Affiliation(s)
- Janet Vonck
- Department of Structural Biology, Max-Planck-Institute of Biophysics, Max-von-Laue-Strasse 3, D-60438 Frankfurt am Main, Germany.
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165
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Lee DW, Oztürk Y, Osyczka A, Cooley JW, Daldal F. Cytochrome bc1-cy fusion complexes reveal the distance constraints for functional electron transfer between photosynthesis components. J Biol Chem 2008; 283:13973-82. [PMID: 18343816 DOI: 10.1074/jbc.m800091200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Photosynthetic (Ps) growth of purple non-sulfur bacteria such as Rhodobacter capsulatus depends on the cyclic electron transfer (ET) between the ubihydroquinone (QH2): cytochrome (cyt) c oxidoreductases (cyt bc1 complex), and the photochemical reaction centers (RC), mediated by either a membrane-bound (cyt c(y)) or a freely diffusible (cyt c2) electron carrier. Previously, we constructed a functional cyt bc1-c(y) fusion complex that supported Ps growth solely relying on membrane-confined ET ( Lee, D.-W., Ozturk, Y., Mamedova, A., Osyczka, A., Cooley, J. W., and Daldal, F. (2006) Biochim. Biophys. Acta 1757, 346-352 ). In this work, we further characterized this cyt bc1-c(y) fusion complex, and used its derivatives with shorter cyt c(y) linkers as "molecular rulers" to probe the distances separating the Ps components. Comparison of the physicochemical properties of both membrane-embedded and purified cyt bc1-c(y) fusion complexes established that these enzymes were matured and assembled properly. Light-activated, time-resolved kinetic spectroscopy analyses revealed that their variants with shorter cyt c(y) linkers exhibited fast, native-like ET rates to the RC via the cyt bc1. However, shortening the length of the cyt c(y) linker decreased drastically this electronic coupling between the cyt bc1-c(y) fusion complexes and the RC, thereby limiting Ps growth. The shortest and still functional cyt c(y) linker was about 45 amino acids long, showing that the minimal distance allowed between the cyt bc1-c(y) fusion complexes and the RC and their surrounding light harvesting proteins was very short. These findings support the notion that membrane-bound Ps components form large, active structural complexes that are "hardwired" for cyclic ET.
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166
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Cooke M, Iosia M, Buford T, Shelmadine B, Hudson G, Kerksick C, Rasmussen C, Greenwood M, Leutholtz B, Willoughby D, Kreider R. Effects of acute and 14-day coenzyme Q10 supplementation on exercise performance in both trained and untrained individuals. J Int Soc Sports Nutr 2008; 5:8. [PMID: 18318910 PMCID: PMC2315638 DOI: 10.1186/1550-2783-5-8] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Accepted: 03/04/2008] [Indexed: 12/19/2022] Open
Abstract
Background To determine whether acute (single dose) and/or chronic (14-days) supplementation of CoQ10 will improve anaerobic and/or aerobic exercise performance by increasing plasma and muscle CoQ10 concentrations within trained and untrained individuals. Methods Twenty-two aerobically trained and nineteen untrained male and female subjects (26.1 ± 7.6 yrs, 172 ± 8.7 cm, 73.5 ± 17 kg, and 21.2 ± 7.0%) were randomized to ingest in a double-blind manner either 100 mg of a dextrose placebo (CON) or a fast-melt CoQ10 supplement (CoQ10) twice a day for 14-days. On the first day of supplementation, subjects donated fasting blood samples and a muscle biopsy. Subjects were then given 200 mg of the placebo or the CoQ10 supplement. Sixty minutes following supplement ingestion, subjects completed an isokinetic knee extension endurance test, a 30-second wingate anaerobic capacity test, and a maximal cardiopulmonary graded exercise test interspersed with 30-minutes of recovery. Additional blood samples were taken immediately following each exercise test and a second muscle biopsy sample was taken following the final exercise test. Subjects consumed twice daily (morning and night), 100 mg of either supplement for a period of 14-days, and then returned to the lab to complete the same battery of tests. Data was analyzed using repeated measures ANOVA with an alpha of 0.05. Results Plasma CoQ10 levels were significantly increased following 2 weeks of CoQ10 supplementation (p < 0.001); while a trend for higher muscle CoQ10 levels was observed after acute CoQ10 ingestion (p = 0.098). A trend for lower serum superoxide dismutase (SOD) was observed following acute supplementation with CoQ10 (p = 0.06), whereas serum malondialdehyde (MDA) tended to be significantly higher (p < 0.05). Following acute ingestion of CoQ10, plasma CoQ10 levels were significantly correlated to muscle CoQ10 levels; maximal oxygen consumption; and treadmill time to exhaustion. A trend for increased time to exhaustion was observed following 2 weeks of CoQ10 supplementation (p = 0.06). Conclusion Acute supplementation with CoQ10 resulted in higher muscle CoQ10 concentration, lower serum SOD oxidative stress, and higher MDA levels during and following exercise. Chronic CoQ10 supplementation increased plasma CoQ10 concentrations and tended to increase time to exhaustion. Results indicate that acute and chronic supplementation of CoQ10 may affect acute and/or chronic responses to various types of exercise.
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Affiliation(s)
- Matthew Cooke
- Exercise & Sport Nutrition Lab; Center for Exercise, Nutrition and Preventive Health; Department of Health, Human Performance & Recreation; Baylor University; Waco, TX, USA
| | - Mike Iosia
- Department of Health, Exercise Science, and Secondary Education; Lee University; Cleveland, TN, USA
| | - Thomas Buford
- Exercise & Sport Nutrition Lab; Center for Exercise, Nutrition and Preventive Health; Department of Health, Human Performance & Recreation; Baylor University; Waco, TX, USA
| | - Brian Shelmadine
- Exercise & Sport Nutrition Lab; Center for Exercise, Nutrition and Preventive Health; Department of Health, Human Performance & Recreation; Baylor University; Waco, TX, USA
| | - Geoffrey Hudson
- Exercise & Sport Nutrition Lab; Center for Exercise, Nutrition and Preventive Health; Department of Health, Human Performance & Recreation; Baylor University; Waco, TX, USA
| | - Chad Kerksick
- Department of Health and Exercise Science; University of Oklahoma; Norman, OK, USA
| | - Christopher Rasmussen
- Exercise & Sport Nutrition Lab; Center for Exercise, Nutrition and Preventive Health; Department of Health, Human Performance & Recreation; Baylor University; Waco, TX, USA
| | - Mike Greenwood
- Exercise & Sport Nutrition Lab; Center for Exercise, Nutrition and Preventive Health; Department of Health, Human Performance & Recreation; Baylor University; Waco, TX, USA
| | - Brian Leutholtz
- Exercise & Sport Nutrition Lab; Center for Exercise, Nutrition and Preventive Health; Department of Health, Human Performance & Recreation; Baylor University; Waco, TX, USA
| | - Darryn Willoughby
- Exercise & Sport Nutrition Lab; Center for Exercise, Nutrition and Preventive Health; Department of Health, Human Performance & Recreation; Baylor University; Waco, TX, USA
| | - Richard Kreider
- Exercise & Sport Nutrition Lab; Center for Exercise, Nutrition and Preventive Health; Department of Health, Human Performance & Recreation; Baylor University; Waco, TX, USA
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167
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Yashonath S, Ghorai PK. Diffusion in Nanoporous Phases: Size Dependence and Levitation Effect. J Phys Chem B 2007; 112:665-86. [DOI: 10.1021/jp076031z] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- S. Yashonath
- Solid State and Structural Chemistry Unit, Center for Condensed Matter Theory, Indian Institute of Science, Bangalore-560012, India
| | - Pradip Kr. Ghorai
- Solid State and Structural Chemistry Unit, Center for Condensed Matter Theory, Indian Institute of Science, Bangalore-560012, India
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168
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A structural perspective on mechanism and function of the cytochrome bc (1) complex. Results Probl Cell Differ 2007; 45:253-78. [PMID: 18038116 DOI: 10.1007/400_2007_042] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The cytochrome bc (1) complex is a fundamental component of the energy conversion machinery of respiratory and photosynthetic electron transfer chains. The multi-subunit membrane protein complex couples electron transfer from hydroquinone to cytochrome c to the translocation of protons across the membrane, thereby substantially contributing to the proton motive force that is used for ATP synthesis. Considerable progress has been made with structural and functional studies towards complete elucidation of the Q cycle mechanism, which was originally proposed by Mitchell 30 years ago. Yet, open questions regarding key steps of the mechanism still remain. The role of the complex as a major source of reactive oxygen species and its implication in pathophysiological conditions has recently gained interest.
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169
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Marques I, Dencher NA, Videira A, Krause F. Supramolecular organization of the respiratory chain in Neurospora crassa mitochondria. EUKARYOTIC CELL 2007; 6:2391-405. [PMID: 17873079 PMCID: PMC2168242 DOI: 10.1128/ec.00149-07] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The existence of specific respiratory supercomplexes in mitochondria of most organisms has gained much momentum. However, its functional significance is still poorly understood. The availability of many deletion mutants in complex I (NADH:ubiquinone oxidoreductase) of Neurospora crassa, distinctly affected in the assembly process, offers unique opportunities to analyze the biogenesis of respiratory supercomplexes. Herein, we describe the role of complex I in assembly of respiratory complexes and supercomplexes as suggested by blue and colorless native polyacrylamide gel electrophoresis and mass spectrometry analyses of mildly solubilized mitochondria from the wild type and eight deletion mutants. As an important refinement of the fungal respirasome model, we found that the standard respiratory chain of N. crassa comprises putative complex I dimers in addition to I-III-IV and III-IV supercomplexes. Three Neurospora mutants able to assemble a complete complex I, lacking only the disrupted subunit, have respiratory supercomplexes, in particular I-III-IV supercomplexes and complex I dimers, like the wild-type strain. Furthermore, we were able to detect the I-III-IV supercomplexes in the nuo51 mutant with no overall enzymatic activity, representing the first example of inactive respirasomes. In addition, III-IV supercomplexes were also present in strains lacking an assembled complex I, namely, in four membrane arm subunit mutants as well as in the peripheral arm nuo30.4 mutant. In membrane arm mutants, high-molecular-mass species of the 30.4-kDa peripheral arm subunit comigrating with III-IV supercomplexes and/or the prohibitin complex were detected. The data presented herein suggest that the biogenesis of complex I is linked with its assembly into supercomplexes.
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Affiliation(s)
- Isabel Marques
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal
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170
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Sugár IP, Biltonen RL. Lateral diffusion of molecules in two-component lipid bilayer: a Monte Carlo simulation study. J Phys Chem B 2007; 109:7373-86. [PMID: 16851844 DOI: 10.1021/jp045669x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Lateral diffusion of membrane components makes possible any in-plane membrane reaction and has a key role in signaling in cell membranes. In this report the equilibrium lateral diffusion of intrinsic molecules in an equimolar DMPC/DSPC mixture is simulated using a thoroughly tested two-state model of two-component phospholipid bilayers. The model has been successful in calculating the excess heat capacity function, the most frequent center-to-center distances between DSPC clusters, and the fractal dimensions of gel clusters (Sugar, I. P., Thompson, T. E., Biltonen, R. L. Biophys. J. 1999, 76, 2099-2110). In the gel/fluid mixed phase region, a diffusing intrinsic molecule may change its state from fluid to gel (or from gel to fluid) at any time. A common characterization of the diffusion of intrinsic molecules is given by the simulated average first-passage time curves. We find that these curves can be described as power functions containing two parameters, alpha and beta, except near the percolation threshold of gel/fluid or compositional clusters. We find also that the intrinsic molecules are involved in approximately normal diffusion, i.e., beta approximately 2 in the extreme gel and fluid phase regions, while in the gel/fluid and gel/gel mixed phase regions the diffusion is anomalous, i.e., beta not equal 2. In the mixed phase regions, when the initial local state of the diffusing molecule is not specified, each component is involved in sub-diffusion (beta > 2). In the gel/fluid mixed phase region molecules situated initially inside a fluid cluster are involved in sub-diffusion, but DMPC molecules situated initially inside a gel cluster are involved in super-diffusion (beta < 2). The possibility of anomalous diffusion in membranes apparently arises because the diffusing molecule visits a variety of different environments characterized by its relative proximity to various membrane components. The diffusion is actually anomalous when the components of the bilayer are nonrandomly distributed. The deviation from random distribution is strongly correlated with beta. Similar to the results of the NMR experiments, the calculated relative diffusion coefficient continuously decreases in the gel/fluid mixed phase region with decreasing temperature. In apparent contradiction, diffusion measured by fluorescence recovery after photobleaching (FRAP) demonstrates the existence of a threshold temperature, below which long-range diffusion of FRAP probe molecules is essentially blocked. This threshold temperature is highly correlated with the percolation temperature of gel clusters.
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Affiliation(s)
- István P Sugár
- Graduate School of Biological Sciences, Mount Sinai School of Medicine, New York, New York 10029, USA
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171
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Li Y, D'Aurelio M, Deng JH, Park JS, Manfredi G, Hu P, Lu J, Bai Y. An Assembled Complex IV Maintains the Stability and Activity of Complex I in Mammalian Mitochondria. J Biol Chem 2007; 282:17557-62. [PMID: 17452320 DOI: 10.1074/jbc.m701056200] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In the mammalian mitochondrial electron transfer system, the majority of electrons enter at complex I, go through complexes III and IV, and are finally delivered to oxygen. Previously we generated several mouse cell lines with suppressed expression of the nuclearly encoded subunit 4 of complex IV. This led to a loss of assembly of complex IV and its defective function. Interestingly, we found that the level of assembled complex I and its activity were also significantly reduced, whereas levels and activity of complex III were normal or up-regulated. The structural and functional dependence of complex I on complex IV was verified using a human cell line carrying a nonsense mutation in the mitochondrially encoded complex IV subunit 1 gene. Our work documents that, although there is no direct electron transfer between them, an assembled complex IV helps to maintain complex I in mammalian cells.
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Affiliation(s)
- Youfen Li
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229, USA
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172
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Lenaz G, Fato R, Formiggini G, Genova ML. The role of Coenzyme Q in mitochondrial electron transport. Mitochondrion 2007; 7 Suppl:S8-33. [PMID: 17485246 DOI: 10.1016/j.mito.2007.03.009] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2006] [Revised: 03/20/2007] [Accepted: 03/22/2007] [Indexed: 12/21/2022]
Abstract
In mitochondria, most Coenzyme Q is free in the lipid bilayer; the question as to whether tightly bound, non-exchangeable Coenzyme Q molecules exist in mitochondrial complexes is still an open question. We review the mechanism of inter-complex electron transfer mediated by ubiquinone and discuss the kinetic consequences of the supramolecular organization of the respiratory complexes (randomly dispersed vs. super-complexes) in terms of Coenzyme Q pool behavior vs. metabolic channeling, respectively, both in physiological and in some pathological conditions. As an example of intra-complex electron transfer, we discuss in particular Complex I, a topic that is still under active investigation.
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Affiliation(s)
- Giorgio Lenaz
- Dipartimento di Biochimica, Università di Bologna, Via Irnerio 48, 40126 Bologna, Italy.
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173
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Boekema EJ, Braun HP. Supramolecular Structure of the Mitochondrial Oxidative Phosphorylation System. J Biol Chem 2007; 282:1-4. [PMID: 17102127 DOI: 10.1074/jbc.r600031200] [Citation(s) in RCA: 172] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The protein complexes of the mitochondrial oxidative phosphorylation system were recently reported to form supramolecular assemblies termed respiratory supercomplexes or respirasomes. These supercomplexes are considered to be of great functional importance. Here we review new insights into supercomplex structure and physiology.
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Affiliation(s)
- Egbert J Boekema
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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174
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Buettner GR, Ng CF, Wang M, Rodgers VGJ, Schafer FQ. A new paradigm: manganese superoxide dismutase influences the production of H2O2 in cells and thereby their biological state. Free Radic Biol Med 2006; 41:1338-50. [PMID: 17015180 PMCID: PMC2443724 DOI: 10.1016/j.freeradbiomed.2006.07.015] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2006] [Revised: 06/09/2006] [Accepted: 07/14/2006] [Indexed: 10/24/2022]
Abstract
The principal source of hydrogen peroxide in mitochondria is thought to be from the dismutation of superoxide via the enzyme manganese superoxide dismutase (MnSOD). However, the nature of the effect of SOD on the cellular production of H(2)O(2) is not widely appreciated. The current paradigm is that the presence of SOD results in a lower level of H(2)O(2) because it would prevent the non-enzymatic reactions of superoxide that form H(2)O(2). The goal of this work was to: a) demonstrate that SOD can increase the flux of H(2)O(2), and b) use kinetic modelling to determine what kinetic and thermodynamic conditions result in SOD increasing the flux of H(2)O(2). We examined two biological sources of superoxide production (xanthine oxidase and coenzyme Q semiquinone, CoQ(*-) that have different thermodynamic and kinetic properties. We found that SOD could change the rate of formation of H(2)O(2) in cases where equilibrium-specific reactions form superoxide with an equilibrium constant (K) less than 1. An example is the formation of superoxide in the electron transport chain (ETC) of the mitochondria by the reaction of ubisemiquinone radical with dioxygen. We measured the rate of release of H(2)O(2) into culture medium from cells with differing levels of MnSOD. We found that the higher the level of SOD, the greater the rate of accumulation of H(2)O(2). Results with kinetic modelling were consistent with this observation; the steady-state level of H(2)O(2) increases if K<1, for example CoQ(*-)+O(2)-->CoQ+O(2)(*-). However, when K>1, e.g. xanthine oxidase forming O(2)(*-), SOD does not affect the steady state-level of H(2)O(2). Thus, the current paradigm that SOD will lower the flux of H(2)O(2) does not hold for the ETC. These observations indicate that MnSOD contributes to the flux of H(2)O(2) in cells and thereby is involved in establishing the cellular redox environment and thus the biological state of the cell.
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Affiliation(s)
- Garry R Buettner
- Free Radical and Radiation Biology Program, EMRB 68, The University of Iowa, Iowa City, IA 52242-1101, USA.
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175
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Lenaz G, Genova ML. Kinetics of integrated electron transfer in the mitochondrial respiratory chain: random collisions vs. solid state electron channeling. Am J Physiol Cell Physiol 2006; 292:C1221-39. [PMID: 17035300 DOI: 10.1152/ajpcell.00263.2006] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recent evidence, mainly based on native electrophoresis, has suggested that the mitochondrial respiratory chain is organized in the form of supercomplexes, due to the aggregation of the main respiratory chain enzymatic complexes. This evidence strongly contrasts the previously accepted model, the Random Diffusion Model, largely based on kinetic studies, stating that the complexes are randomly distributed in the lipid bilayer of the inner membrane and functionally connected by lateral diffusion of small redox molecules, i.e., coenzyme Q and cytochrome c. This review critically examines the experimental evidence, both structural and functional, pertaining to the two models and attempts to provide an updated view of the organization of the respiratory chain and of its kinetic consequences. The conclusion that structural respiratory assemblies exist is overwhelming, whereas the expected functional consequence of substrate channeling between the assembled enzymes is controversial. Examination of the available evidence suggests that, although the supercomplexes are structurally stable, their kinetic competence in substrate channeling is more labile and may depend on the system under investigation and the assay conditions.
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Affiliation(s)
- Giorgio Lenaz
- Dipartimento di Biochimica "G. Moruzzi," Via Irnerio 48, 40126 Bologna, Italy.
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176
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Melo E, Martins J. Kinetics of bimolecular reactions in model bilayers and biological membranes. A critical review. Biophys Chem 2006; 123:77-94. [PMID: 16730881 DOI: 10.1016/j.bpc.2006.05.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2006] [Revised: 05/08/2006] [Accepted: 05/09/2006] [Indexed: 10/24/2022]
Abstract
The quantitative study of the probability of molecular encounters giving rise to a reaction in membranes is a challenging discipline. Model systems, model in the sense that they use model bilayers and model reactants, have been widely used for this purpose, but the methodologies employed for the analysis of the results obtained in experiments, and for experimental design, are so disparate that a concerned experimentalist has difficulty in deciding about the value of each approach. This review intends to examine the several approaches that can be found in the literature showing, when feasible, the weakness, strengths and limits of application of each of them. There is not, so far, a full experimental validation of the most promising theories for the analysis of reactions in two dimensions, what leaves open a large field for new research. The major challenge resides in the time range in which the processes take place, but the possibilities of the existing techniques for these studies are far from exhausted. We review also the attempts of several authors to quantitatively analyze the kinetics of reactions in biological membranes. Especially in this field, the recently developed microspectroscopies enclose a still unexplored potential.
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Affiliation(s)
- Eurico Melo
- Instituto de Tecnologia Química e Biológica, Oeiras, Portugal.
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177
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Geng AL, Guo YM. Effects of dietary coenzyme Q10supplementation on hepatic mitochondrial function and the activities of respiratory chain-related enzymes in ascitic broiler chickens. Br Poult Sci 2006; 46:626-34. [PMID: 16359119 DOI: 10.1080/00071660500273292] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
1. One hundred and sixty 1-d-old Arbor Acre male broiler chicks were fed with maize-soybean based diets for 6 weeks in a 2 x 2 factorial experiment. The factors were CoQ10 supplementation (0 or 40 mg/kg) and Escherichia coli lipopolysaccharide (LPS) challenge (LPS or saline). 2. CoQ10 was supplemented from d 1. From d 18, the chickens received three weekly i.p. injections of LPS (1.0 mg/kg BW) or an equivalent amount of sterile saline as control. From d 10 on, all chickens were exposed to low ambient temperature (12 to 15 degrees C) to induce ascites. 3. The blood packed cell volume and ascites heart index of broiler chickens were reduced by dietary CoQ10 supplementation. Mitochondrial State 3 and State 4 respiration, respiratory control ratio and phosphate oxygen ratio were not changed, but H+/site stoichiometry of complex II + III was elevated by dietary CoQ10 supplementation. 4. Cytochrome c oxidase and H+-ATPase activity were increased by CoQ10 supplementation, whereas NADH cytochrome c reductase and succinate cytochrome c reductase were not influenced. Mitochondrial anti-ROS capability was increased and malondialdehyde content was decreased by CoQ10 supplementation. 5. The work suggested that dietary CoQ10 supplementation could reduce broiler chickens' susceptibility to ascites, which might be the result of improving hepatic mitochondrial function, some respiratory chain-related enzymes activities and mitochondrial antioxidative capability.
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Affiliation(s)
- A L Geng
- Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, China Agricultural University, Beijing
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178
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Krause F, Scheckhuber CQ, Werner A, Rexroth S, Reifschneider NH, Dencher NA, Osiewacz HD. OXPHOS Supercomplexes: respiration and life-span control in the aging model Podospora anserina. Ann N Y Acad Sci 2006; 1067:106-15. [PMID: 16803975 DOI: 10.1196/annals.1354.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Recent biochemical evidence has indicated the existence of respiratory supercomplexes as well as ATP synthase oligomers in the inner mitochondrial membrane of different eukaryotes. We have studied the organization of the respiratory chain of a wild-type strain and of two long-lived mutants of the filamentous fungus Podospora anserina. This aging model is able to respire by either the standard or the alternative pathway. In the latter, electrons are directly transferred from ubiquinol to the alternative oxidase (AOX) and thus bypass complexes III and IV. We showed that the two pathways are composed of distinct respiratory supercomplexes. These data are of significance for the understanding of both respiratory pathways as well as of life-span control and aging.
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Affiliation(s)
- Frank Krause
- Physical Biochemistry, Department of Chemistry, Darmstadt University of Technology, Germany.
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179
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Piccoli C, Scrima R, Boffoli D, Capitanio N. Control by cytochrome c oxidase of the cellular oxidative phosphorylation system depends on the mitochondrial energy state. Biochem J 2006; 396:573-83. [PMID: 16533168 PMCID: PMC1482809 DOI: 10.1042/bj20060077] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2006] [Revised: 03/08/2006] [Accepted: 03/13/2006] [Indexed: 02/08/2023]
Abstract
Recent measurements of the flux control exerted by cytochrome c oxidase on the respiratory activity in intact cells have led to a re-appraisal of its regulatory function. We have further extended this in vivo study in the framework of the Metabolic Control Analysis and evaluated the impact of the mitochondrial transmembrane electrochemical potential (Deltamu(H+)) on the control strength of the oxidase. The results indicate that, under conditions mimicking the mitochondrial State 4 of respiration, both the flux control coefficient and the threshold value of cytochrome oxidase are modified with respect to the uncoupled condition. The results obtained are consistent with a model based on changes in the assembly state of the oxidative phosphorylation enzyme complexes and possible implications in the understanding of exercise-intolerance of human neuromuscular degenerative diseases are discussed.
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Key Words
- cytochrome c oxidase
- metabolic flux control
- mitochondrial transmembrane electrochemical potential
- oxidative phosphorylation
- respirasome
- cccp, carbonyl cyanide m-chlorophenylhydrazone
- cox, cytochrome c oxidase
- dmem, dulbecco's modified eagle's medium
- dnp, 2,4-dinitrophenol
- m(f)ca, metabolic (flux) control analysis
- mtdna, mitochondrial dna
- oxphos, oxidative phosphorylation
- tmpd, n,n,n′,n′-tetramethyl-p-phenylenediamine
- δph, transmembrane ph gradient
- δμh+, mitochondrial transmembrane electrochemical potential
- δψ, transmembrane electrical potential
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Affiliation(s)
- Claudia Piccoli
- Department of Biomedical Science, University of Foggia, 71100 Foggia, Italy
| | - Rosella Scrima
- Department of Biomedical Science, University of Foggia, 71100 Foggia, Italy
| | - Domenico Boffoli
- Department of Biomedical Science, University of Foggia, 71100 Foggia, Italy
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180
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D'Aurelio M, Gajewski CD, Lenaz G, Manfredi G. Respiratory chain supercomplexes set the threshold for respiration defects in human mtDNA mutant cybrids. Hum Mol Genet 2006; 15:2157-69. [PMID: 16740593 DOI: 10.1093/hmg/ddl141] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mitochondrial DNA (mtDNA) mutations cause heterogeneous disorders in humans. MtDNA exists in multiple copies per cell, and mutations need to accumulate beyond a critical threshold to cause disease, because coexisting wild-type mtDNA can complement the genetic defect. A better understanding of the molecular determinants of functional complementation among mtDNA molecules could help us shedding some light on the mechanisms modulating the phenotypic expression of mtDNA mutations in mitochondrial diseases. We studied mtDNA complementation in human cells by fusing two cell lines, one containing a homoplasmic mutation in a subunit of respiratory chain complex IV, COX I, and the other a distinct homoplasmic mutation in a subunit of complex III, cytochrome b. Upon cell fusion, respiration is recovered in hybrids cells, indicating that mitochondria fuse and exchange genetic and protein materials. Mitochondrial functional complementation occurs frequently, but with variable efficiency. We have investigated by native gel electrophoresis the molecular organization of the mitochondrial respiratory chain in complementing hybrid cells. We show that the recovery of mitochondrial respiration correlates with the presence of supramolecular structures (supercomplexes) containing complexes I, III and IV. We suggest that critical amounts of complexes III or IV are required in order for supercomplexes to form and provide mitochondrial functional complementation. From these findings, supercomplex assembly emerges as a necessary step for respiration, and its defect sets the threshold for respiratory impairment in mtDNA mutant cells.
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Affiliation(s)
- Marilena D'Aurelio
- Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York, NY 10021, USA
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181
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Schäfer E, Seelert H, Reifschneider NH, Krause F, Dencher NA, Vonck J. Architecture of Active Mammalian Respiratory Chain Supercomplexes. J Biol Chem 2006; 281:15370-5. [PMID: 16551638 DOI: 10.1074/jbc.m513525200] [Citation(s) in RCA: 218] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In the inner mitochondrial membrane, the respiratory chain complexes generate an electrochemical proton gradient, which is utilized to synthesize most of the cellular ATP. According to an increasing number of biochemical studies, these complexes are assembled into supercomplexes. However, little is known about the architecture of the proposed multicomplex assemblies. Here, we report the electron microscopic characterization of the two respiratory chain supercomplexes I1III2 and I1III2IV1 in bovine heart mitochondria, which are also two major supercomplexes in human mitochondria. After purification and demonstration of enzymatic activity, their structures in projection were determined by single particle image analysis. A difference map between the supercomplexes I1III2 and I1III2IV1 closely fits the x-ray structure of monocomplex IV and shows its location in the assembly. By comparing different views of supercomplex I1III2IV1, the location and mutual arrangement of complex I and the complex III dimer are discussed. Detailed knowledge of the architecture of the active supercomplexes is a prerequisite for a deeper understanding of energy conversion by mitochondria in mammals.
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Affiliation(s)
- Eva Schäfer
- Department of Chemistry, Physical Biochemistry, Darmstadt University of Technology, Petersenstrasse 22, D-64287 Darmstadt, Germany
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182
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Lenaz G, Fato R, Genova ML, Bergamini C, Bianchi C, Biondi A. Mitochondrial Complex I: structural and functional aspects. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:1406-20. [PMID: 16828051 DOI: 10.1016/j.bbabio.2006.05.007] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2006] [Revised: 04/10/2006] [Accepted: 05/05/2006] [Indexed: 12/20/2022]
Abstract
This review examines two aspects of the structure and function of mitochondrial Complex I (NADH Coenzyme Q oxidoreductase) that have become matter of recent debate. The supramolecular organization of Complex I and its structural relation with the remainder of the respiratory chain are uncertain. Although the random diffusion model [C.R. Hackenbrock, B. Chazotte, S.S. Gupte, The random collision model and a critical assessment of diffusion and collision in mitochondrial electron transport, J. Bioenerg. Biomembranes 18 (1986) 331-368] has been widely accepted, recent evidence suggests the presence of supramolecular aggregates. In particular, evidence for a Complex I-Complex III supercomplex stems from both structural and kinetic studies. Electron transfer in the supercomplex may occur by electron channelling through bound Coenzyme Q in equilibrium with the pool in the membrane lipids. The amount and nature of the lipids modify the aggregation state and there is evidence that lipid peroxidation induces supercomplex disaggregation. Another important aspect in Complex I is its capacity to reduce oxygen with formation of superoxide anion. The site of escape of the single electron is debated and either FMN, iron-sulphur clusters, and ubisemiquinone have been suggested. The finding in our laboratory that two classes of hydrophobic inhibitors have opposite effects on superoxide production favours an iron-sulphur cluster (presumably N2) is the direct oxygen reductant. The implications in human pathology of better knowledge on these aspects of Complex I structure and function are briefly discussed.
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Affiliation(s)
- Giorgio Lenaz
- Department of Biochemistry, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy.
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183
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Dudkina NV, Heinemeyer J, Sunderhaus S, Boekema EJ, Braun HP. Respiratory chain supercomplexes in the plant mitochondrial membrane. TRENDS IN PLANT SCIENCE 2006; 11:232-40. [PMID: 16616870 DOI: 10.1016/j.tplants.2006.03.007] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2006] [Revised: 02/20/2006] [Accepted: 03/27/2006] [Indexed: 05/08/2023]
Abstract
The intricate, heavily folded inner membrane of mitochondria houses the respiratory chain complexes. These complexes, together with the ATP synthase complex, are responsible for energy production, which is stored as ATP. The structure of the individual membrane-bound protein components has been well characterized. In particular, the use of Blue-native polyacrylamide gel electrophoresis has been instrumental in recent years in providing evidence that these components are organized into supercomplexes. Single particle electron microscopy studies have enabled a structural characterization of some of the mitochondrial supercomplexes. This has provided the opportunity to define a functional role for these supercomplexes for the first time, in particular for the dimeric ATP synthase complex, which appears to be responsible for the folding of the inner mitochondrial membrane.
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Affiliation(s)
- Natalya V Dudkina
- Department of Biophysical Chemistry, GBB, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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184
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Bayir H, Fadeel B, Palladino MJ, Witasp E, Kurnikov IV, Tyurina YY, Tyurin VA, Amoscato AA, Jiang J, Kochanek PM, DeKosky ST, Greenberger JS, Shvedova AA, Kagan VE. Apoptotic interactions of cytochrome c: redox flirting with anionic phospholipids within and outside of mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:648-59. [PMID: 16740248 DOI: 10.1016/j.bbabio.2006.03.002] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2005] [Revised: 02/17/2006] [Accepted: 03/06/2006] [Indexed: 11/26/2022]
Abstract
Since the (re)discovery of cytochrome c (cyt c) in the early 1920s and subsequent detailed characterization of its structure and function in mitochondrial electron transport, it took over 70 years to realize that cyt c plays a different, not less universal role in programmed cell death, apoptosis, by interacting with several proteins and forming apoptosomes. Recently, two additional essential functions of cyt c in apoptosis have been discovered that are carried out via its interactions with anionic phospholipids: a mitochondria specific phospholipid, cardiolipin (CL), and plasma membrane phosphatidylserine (PS). Execution of apoptotic program in cells is accompanied by substantial and early mitochondrial production of reactive oxygen species (ROS). Because antioxidant enhancements protect cells against apoptosis, ROS production was viewed not as a meaningless side effect of mitochondrial disintegration but rather playing some - as yet unidentified - role in apoptosis. This conundrum has been resolved by establishing that mitochondria contain a pool of cyt c, which interacts with CL and acts as a CL oxygenase. The oxygenase is activated during apoptosis, utilizes generated ROS and causes selective oxidation of CL. The oxidized CL is required for the release of pro-apoptotic factors from mitochondria into the cytosol. This redox mechanism of cyt c is realized earlier than its other well-recognized functions in the formation of apoptosomes and caspase activation. In the cytosol, released cyt c interacts with another anionic phospholipid, PS, and catalyzes its oxidation in a similar oxygenase reaction. Peroxidized PS facilitates its externalization essential for the recognition and clearance of apoptotic cells by macrophages. Redox catalysis of plasma membrane PS oxidation constitutes an important redox-dependent function of cyt c in apoptosis and phagocytosis. Thus, cyt c acts as an anionic phospholipid specific oxygenase activated and required for the execution of essential stages of apoptosis. This review is focused on newly discovered redox mechanisms of complexes of cyt c with anionic phospholipids and their role in apoptotic pathways in health and disease.
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Affiliation(s)
- H Bayir
- Center for Free Radical and Antioxidant Health, Pittsburgh, PA 15219, USA.
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185
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Lenaz G, Baracca A, Fato R, Genova ML, Solaini G. New insights into structure and function of mitochondria and their role in aging and disease. Antioxid Redox Signal 2006; 8:417-37. [PMID: 16677088 DOI: 10.1089/ars.2006.8.417] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
This review covers some novel findings on mitochondrial biochemistry and discusses diseases due to mitochondrial DNA mutations as a model of the changes occurring during physiological aging. The random collision model of organization of the mitochondrial respiratory chain has been recently challenged on the basis of findings of supramolecular organization of respiratory chain complexes. The source of superoxide in Complex I is discussed on the basis of laboratory experiments using a series of specific inhibitors and is presumably iron sulfur center N2. Maternally inherited diseases due to mutations of structural genes in mitochondrial DNA are surveyed as a model of alterations mimicking those occurring during normal aging. The molecular defects in senescence are surveyed on the basis of the "Mitochondrial Theory of Aging", establishing mitochondrial DNA somatic mutations, caused by accumulation of oxygen radical damage, to be at the basis of cellular senescence. Mitochondrial production of reactive oxygen species increases with aging and mitochondrial DNA mutations and deletions accumulate and may be responsible for oxidative phosphorylation defects. Evidence is presented favoring the mitochondrial theory, with primary mitochondrial alterations, although the problem is made more complex by changes in the cross-talk between nuclear and mitochondrial DNA.
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Affiliation(s)
- Giorgio Lenaz
- Dipartimento di Biochimica, Università di Bologna, Bologna, Italy.
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186
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Andreyev AY, Kushnareva YE, Starkov AA. Mitochondrial metabolism of reactive oxygen species. BIOCHEMISTRY (MOSCOW) 2005; 70:200-14. [PMID: 15807660 DOI: 10.1007/s10541-005-0102-7] [Citation(s) in RCA: 830] [Impact Index Per Article: 43.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Oxidative stress is considered a major contributor to etiology of both "normal" senescence and severe pathologies with serious public health implications. Mitochondria generate reactive oxygen species (ROS) that are thought to augment intracellular oxidative stress. Mitochondria possess at least nine known sites that are capable of generating superoxide anion, a progenitor ROS. Mitochondria also possess numerous ROS defense systems that are much less studied. Studies of the last three decades shed light on many important mechanistic details of mitochondrial ROS production, but the bigger picture remains obscure. This review summarizes the current knowledge about major components involved in mitochondrial ROS metabolism and factors that regulate ROS generation and removal. An integrative, systemic approach is applied to analysis of mitochondrial ROS metabolism, which is now dissected into mitochondrial ROS production, mitochondrial ROS removal, and mitochondrial ROS emission. It is suggested that mitochondria augment intracellular oxidative stress due primarily to failure of their ROS removal systems, whereas the role of mitochondrial ROS emission is yet to be determined and a net increase in mitochondrial ROS production in situ remains to be demonstrated.
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Affiliation(s)
- A Yu Andreyev
- Alumni of Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia
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187
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Farrell SR, Thorpe C. Augmenter of liver regeneration: a flavin-dependent sulfhydryl oxidase with cytochrome c reductase activity. Biochemistry 2005; 44:1532-41. [PMID: 15683237 DOI: 10.1021/bi0479555] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Augmenter of liver regeneration (ALR; hepatopoietin) is a recently discovered enigmatic flavin-linked sulfhydryl oxidase. An N-terminal His-tagged construct of the short form of the human protein has been overexpressed in Escherichia coli. Several lines of evidence suggest that, contrary to a recent report, human ALR is a disulfide-bridged dimer (linked via C15-C124) with two free cysteine residues (C74 and 85) per monomer. The C15-124 disulfides are not critical for dimer formation and have insignificant impact on the dithiothreitol (DTT) oxidase activity of ALR. Although the crystal structure of rat ALR shows a proximal disulfide (C62-C65) poised to interact with the FAD prosthetic group [Wu, C. K., Dailey, T. A., Dailey, H. A., Wang, B. C., and Rose, J. P. (2003) Protein Sci. 12, 1109-1118], only flavin reduction is evident during redox titrations of the enzyme. ALR forms large amounts of neutral semiquinone during aerobic turnover with DTT. This semiquinone arises, in part, by comproportionation between flavin centers within the dimer. Surprisingly, cytochrome c is about a 100-fold better electron acceptor for ALR than oxygen when DTT is the reducing substrate. These data suggest that this poorly understood flavoenzyme may not function as a sulfhydryl oxidase within the mitochondrial intermembrane space but may communicate with the respiratory chain via the mediation of cytochrome c.
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Affiliation(s)
- Scott R Farrell
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA
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188
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Mileykovskaya E, Zhang M, Dowhan W. Cardiolipin in energy transducing membranes. BIOCHEMISTRY (MOSCOW) 2005; 70:154-8. [PMID: 15807653 DOI: 10.1007/s10541-005-0095-2] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Cardiolipin is a phospholipid located exclusively in energy transducing membranes such as the bacterial cytoplasmic membrane and the inner membrane of mitochondria. It plays both a structural and a functional role in many multimeric complexes associated with these membranes. The role of cardiolipin in higher order organization of components of the mitochondrial respiratory chain revealed by a combined molecular genetic and biochemical approach is described.
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Affiliation(s)
- E Mileykovskaya
- Department of Biochemistry and Molecular Biology, University of Texas-Houston, Medical School, Houston, TX 77030, USA.
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189
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Genova ML, Bianchi C, Lenaz G. Supercomplex organization of the mitochondrial respiratory chain and the role of the Coenzyme Q pool: pathophysiological implications. Biofactors 2005; 25:5-20. [PMID: 16873926 DOI: 10.1002/biof.5520250103] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In this review we examine early and recent evidence for an aggregated organization of the mitochondrial respiratory chain. Blue Native Electrophoresis suggests that in several types of mitochondria Complexes I, III and IV are aggregated as fixed supramolecular units having stoichiometric proportions of each individual complex. Kinetic evidence by flux control analysis agrees with this view, however the presence of Complex IV in bovine mitochondria cannot be demonstrated, presumably due to high levels of free Complex. Since most Coenzyme Q appears to be largely free in the lipid bilayer of the inner membrane, binding of Coenzyme Q molecules to the Complex I-III aggregate is forced by its dissociation equilibrium; furthermore free Coenzyme Q is required for succinate-supported respiration and reverse electron transfer. The advantage of the supercomplex organization is in a more efficient electron transfer by channelling of the redox intermediates and in the requirement of a supramolecular structure for the correct assembly of the individual complexes. Preliminary evidence suggests that dilution of the membrane proteins with extra phospholipids and lipid peroxidation may disrupt the supercomplex organization. This finding has pathophysiological implications, in view of the role of oxidative stress in the pathogenesis of many diseases.
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190
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Krause F, Reifschneider NH, Vocke D, Seelert H, Rexroth S, Dencher NA. “Respirasome”-like Supercomplexes in Green Leaf Mitochondria of Spinach. J Biol Chem 2004; 279:48369-75. [PMID: 15342644 DOI: 10.1074/jbc.m406085200] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Higher plant mitochondria have many unique features compared with their animal and fungal counterparts. This is to a large extent related to the close functional interdependence of mitochondria and chloroplasts, in which the two ATP-generating processes of oxidative phosphorylation and photosynthesis, respectively, take place. We show that digitonin treatment of mitochondria contaminated with chloroplasts from spinach (Spinacia oleracea) green leaves at two different buffer conditions, performed to solubilize oxidative phosphorylation supercomplexes, selectively extracts the mitochondrial membrane protein complexes and only low amounts of stroma thylakoid membrane proteins. By analysis of digitonin extracts from partially purified mitochondria of green leaves from spinach using blue and colorless native electrophoresis, we demonstrate for the first time that in green plant tissue a substantial proportion of the respiratory complex IV is assembled with complexes I and III into "respirasome"-like supercomplexes, previously observed in mammalian, fungal, and non-green plant mitochondria only. Thus, fundamental features of the supramolecular organization of the standard respiratory complexes I, III, and IV as a respirasome are conserved in all higher eukaryotes. Because the plant respiratory chain is highly branched possessing additional alternative enzymes, the functional implications of the occurrence of respiratory supercomplexes in plant mitochondria are discussed.
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Affiliation(s)
- Frank Krause
- Physical Biochemistry, Department of Chemistry, Darmstadt University of Technology, Petersenstrasse 22, D-64287 Darmstadt, Germany.
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191
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Schägger H, de Coo R, Bauer MF, Hofmann S, Godinot C, Brandt U. Significance of Respirasomes for the Assembly/Stability of Human Respiratory Chain Complex I. J Biol Chem 2004; 279:36349-53. [PMID: 15208329 DOI: 10.1074/jbc.m404033200] [Citation(s) in RCA: 238] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We showed that the human respiratory chain is organized in supramolecular assemblies of respiratory chain complexes, the respirasomes. The mitochondrial complexes I (NADH dehydrogenase) and III (cytochrome c reductase) form a stable core respirasome to which complex IV (cytochrome c oxidase) can also bind. An analysis of the state of respirasomes in patients with an isolated deficiency of single complexes provided evidence that the formation of respirasomes is essential for the assembly/stability of complex I, the major entry point of respiratory chain substrates. Genetic alterations leading to a loss of complex III prevented respirasome formation and led to the secondary loss of complex I. Therefore, primary complex III assembly deficiencies presented as combined complex III/I defects. This dependence of complex I assembly/stability on respirasome formation has important implications for the diagnosis of mitochondrial respiratory chain disorders.
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Affiliation(s)
- Hermann Schägger
- Institut für Biochemie I, Zentrum der Biologischen Chemie, Fachbereich Medizin, Universität Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany.
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192
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Bianchi C, Genova ML, Parenti Castelli G, Lenaz G. The mitochondrial respiratory chain is partially organized in a supercomplex assembly: kinetic evidence using flux control analysis. J Biol Chem 2004; 279:36562-9. [PMID: 15205457 DOI: 10.1074/jbc.m405135200] [Citation(s) in RCA: 199] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The model of the respiratory chain in which the enzyme complexes are independently embedded in the lipid bilayer of the inner mitochondrial membrane and connected by randomly diffusing coenzyme Q and cytochrome c is mostly favored. However, multicomplex units can be isolated from mammalian mitochondria, suggesting a model based on direct electron channeling between complexes. Kinetic testing using metabolic flux control analysis can discriminate between the two models: the former model implies that each enzyme may be rate-controlling to a different extent, whereas in the latter, the whole metabolic pathway would behave as a single supercomplex and inhibition of any one of its components would elicit the same flux control. In particular, in the absence of other components of the oxidative phosphorylation apparatus (i.e. ATP synthase, membrane potential, carriers), the existence of a supercomplex would elicit a flux control coefficient near unity for each respiratory complex, and the sum of all coefficients would be well above unity. Using bovine heart mitochondria and submitochondrial particles devoid of substrate permeability barriers, we investigated the flux control coefficients of the complexes involved in aerobic NADH oxidation (I, III, IV) and in succinate oxidation (II, III, IV). Both Complexes I and III were found to be highly rate-controlling over NADH oxidation, a strong kinetic evidence suggesting the existence of functionally relevant association between the two complexes, whereas Complex IV appears randomly distributed. Moreover, we show that Complex II is fully rate-limiting for succinate oxidation, clearly indicating the absence of substrate channeling toward Complexes III and IV.
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Affiliation(s)
- Cristina Bianchi
- Dipartimento di Biochimica G. Moruzzi, Università di Bologna, Via Irnerio 48, 40126 Bologna, Italy
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193
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Krause F, Scheckhuber CQ, Werner A, Rexroth S, Reifschneider NH, Dencher NA, Osiewacz HD. Supramolecular Organization of Cytochrome c Oxidase- and Alternative Oxidase-dependent Respiratory Chains in the Filamentous Fungus Podospora anserina. J Biol Chem 2004; 279:26453-61. [PMID: 15044453 DOI: 10.1074/jbc.m402756200] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To elucidate the molecular basis of the link between respiration and longevity, we have studied the organization of the respiratory chain of a wild-type strain and of two long-lived mutants of the filamentous fungus Podospora anserina. This established aging model is able to respire by either the standard or the alternative pathway. In the latter pathway, electrons are directly transferred from ubiquinol to the alternative oxidase and thus bypass complexes III and IV. We show that the cytochrome c oxidase pathway is organized according to the mammalian "respirasome" model (Schägger, H., and Pfeiffer, K. (2000) EMBO J. 19, 1777-1783). In contrast, the alternative pathway is composed of distinct supercomplexes of complexes I and III (i.e. I(2) and I(2)III(2)), which have not been described so far. Enzymatic analysis reveals distinct functional properties of complexes I and III belonging to either cytochrome c oxidase- or alternative oxidase-dependent pathways. By a gentle colorless-native PAGE, almost all of the ATP synthases from mitochondria respiring by either pathway were preserved in the dimeric state. Our data are of significance for the understanding of both respiratory pathways as well as lifespan control and aging.
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Affiliation(s)
- Frank Krause
- Department of Chemistry, Physical Biochemistry, Darmstadt University of Technology, Petersenstrasse 22, D-64287 Darmstadt, Germany.
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194
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GENOVA MARIALUISA, PICH MILENAMERLO, BERNACCHIA ANDREA, BIANCHI CRISTINA, BIONDI ANNALISA, BOVINA CARLA, FALASCA ANNAIDA, FORMIGGINI GABRIELLA, CASTELLI GIOVANNAPARENTI, LENAZ GIORGIO. The Mitochondrial Production of Reactive Oxygen Species in Relation to Aging and Pathology. Ann N Y Acad Sci 2004. [DOI: 10.1196/annals.1293.010] [Citation(s) in RCA: 167] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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195
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Genova ML, Pich MM, Bernacchia A, Bianchi C, Biondi A, Bovina C, Falasca AI, Formiggini G, Castelli GP, Lenaz G. The mitochondrial production of reactive oxygen species in relation to aging and pathology. Ann N Y Acad Sci 2004; 1011:86-100. [PMID: 15126287 DOI: 10.1007/978-3-662-41088-2_10] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mitochondria are known to be strong producers of reactive oxygen species (ROS) and, at the same time, particularly susceptible to the oxidative damage produced by their action on lipids, proteins, and DNA. In particular, damage to mtDNA induces alterations to the polypeptides encoded by mtDNA in the respiratory complexes, with consequent decrease of electron transfer, leading to further production of ROS and thus establishing a vicious circle of oxidative stress and energetic decline. This deficiency in mitochondrial energetic capacity is considered the cause of aging and age-related degenerative diseases. Complex I would be the enzyme most affected by ROS, since it contains seven of the 13 subunits encoded by mtDNA. Accordingly, we found that complex I activity is significantly affected by aging in rat brain and liver mitochondria as well as in human platelets. Moreover, due to its rate control over aerobic respiration, such alterations are reflected on the entire oxidative phosphorylation system. We also investigated the role of mitochondrial complex I in superoxide production and found that the one-electron donor to oxygen is most probably the Fe-S cluster N2. Short chain coenzyme Q (CoQ) analogues enhance ROS formation, presumably by mediating electron transfer from N2 to oxygen, both in bovine heart SMP and in cultured HL60 cells. Nevertheless, we have accumulated much evidence of the antioxidant role of reduced CoQ(10) in several cellular systems and demonstrated the importance of DT-diaphorase and other internal cellular reductases to reduce exogenous CoQ(10) after incorporation.
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Affiliation(s)
- Maria Luisa Genova
- Dipartimento di Biochimica "G. Moruzzi," University of Bologna, 40126 Bologna, Italy
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196
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Abstract
Adenosine triphosphate (ATP)-sensitive potassium (K(ATP)) channels allow coupling of membrane potential to cellular metabolic status. Two K(ATP) channel subtypes coexist in the myocardium, with one subtype located in the sarcolemma (sarcK(ATP)) membrane and the other in the inner membrane of the mitochondria (mitoK(ATP)). The K(ATP) channels can be pharmacologically modulated by a family of structurally diverse agents of varied potency and selectivity, collectively known as potassium channel openers and blockers. Sufficient evidence exists to indicate that the K(ATP) channels and, in particular, the mitoK(ATP) channels play an important role both as a trigger and an effector in surgical cardioprotection. In this review, the biochemistry and surgical specificity of the K(ATP) channels are examined.
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Affiliation(s)
- James D McCully
- Division of Cardiothoracic Surgery, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02115, USA.
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197
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Bianchi C, Fato R, Genova ML, Parenti Castelli G, Lenaz G. Structural and functional organization of Complex I in the mitochondrial respiratory chain. Biofactors 2003; 18:3-9. [PMID: 14695915 DOI: 10.1002/biof.5520180202] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Metabolic flux control analysis of NADH oxidation in bovine heart submitochondrial particles revealed high flux control coefficients for both Complex I and Complex III, suggesting that the two enzymes are functionally associated as a single enzyme, with channelling of the common substrate, Coenzyme Q. This is in contrast with the more accepted view of a mobile diffusable Coenzyme Q pool between these enzymes. Dilution with phospholipids of a mitochondrial fraction enriched in Complexes I and III, with consequent increased theoretical distance between complexes, determines adherence to pool behavior for Coenzyme Q, but only at dilution higher than 1:5 (protein:phospholipids), whereas, at lower phospholipid content, the turnover of NADH cytochrome c reductase is higher than expected by the pool equation.
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198
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Appaix F, Guerrero K, Rampal D, Izikki M, Kaambre T, Sikk P, Brdiczka D, Riva-Lavieille C, Olivares J, Longuet M, Antonsson B, Saks VA. Bax and heart mitochondria: uncoupling and inhibition of respiration without permeability transition. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1556:155-67. [PMID: 12460673 DOI: 10.1016/s0005-2728(02)00358-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The effects of Bax (full-length, FL, and C-terminal truncated, DeltaC) on respiration rate, membrane potential, MgATPase activity and kinetics of regulation of respiration were studied in isolated rat heart mitochondria and permeabilized cardiomyocytes. The results showed that while both Bax-FL and Bax-DeltaC permeabilized the outer mitochondrial membrane, released cytochrome c and reduced the respiration rate, the latter could be fully restored by exogenous cytochrome c only in the case of Bax-DeltaC, but not in presence of Bax-FL. In addition, Bax-FL but not Bax-DeltaC increased the MgATPase activity, and their effects on the mitochondrial membrane potential were quantitatively different. None of these effects was sensitive to cyclosporin A (CsA). It is concluded that Bax-FL affects both the outer and the inner mitochondrial membranes by: (1) opening large pores in the outer membrane; (2) inhibiting some segments of the respiratory chain in the inner membrane; and (3) uncoupling the inner mitochondrial membrane by increasing proton leak without opening the permeability transition pore (PTP).
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Affiliation(s)
- Florence Appaix
- University of Joseph Fourier, B.P. 35 X, 38041 Cedex 9, Grenoble, France
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199
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Dos Santos P, Kowaltowski AJ, Laclau MN, Seetharaman S, Paucek P, Boudina S, Thambo JB, Tariosse L, Garlid KD. Mechanisms by which opening the mitochondrial ATP- sensitive K(+) channel protects the ischemic heart. Am J Physiol Heart Circ Physiol 2002; 283:H284-95. [PMID: 12063301 DOI: 10.1152/ajpheart.00034.2002] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Diazoxide opening of the mitochondrial ATP-sensitive K(+) (mitoK(ATP)) channel protects the heart against ischemia-reperfusion injury by unknown mechanisms. We investigated the mechanisms by which mitoK(ATP) channel opening may act as an end effector of cardioprotection in the perfused rat heart model, in permeabilized fibers, and in rat heart mitochondria. We show that diazoxide pretreatment preserves the normal low outer membrane permeability to nucleotides and cytochrome c and that these beneficial effects are abolished by the mitoK(ATP) channel inhibitor 5-hydroxydecanoate. We hypothesize that an open mitoK(ATP) channel during ischemia maintains the tight structure of the intermembrane space that is required to preserve the normal low outer membrane permeability to ADP and ATP. This hypothesis is supported by findings in mitochondria showing that small decreases in intermembrane space volume, induced by either osmotic swelling or diazoxide, increased the half-saturation constant for ADP stimulation of respiration and sharply reduced ATP hydrolysis. These effects are proposed to lead to preservation of adenine nucleotides during ischemia and efficient energy transfer upon reperfusion.
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Affiliation(s)
- Pierre Dos Santos
- Unité 441 Athérosclérose and IFR 4, Institut National de la Santé et de la Recherche Médicale, 33600 Pessac, France
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200
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Lemeshko VV. Cytochrome c sorption-desorption effects on the external NADH oxidation by mitochondria: experimental and computational study. J Biol Chem 2002; 277:17751-7. [PMID: 11886867 DOI: 10.1074/jbc.m201002200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The rupture of the outer mitochondrial membrane is known to be critical for cell death, but the mechanism, specifically its redox-signaling aspects, still needs to be studied in more detail. In this work, the external NADH oxidation by rat liver mitochondria was studied under the outer membrane rupture induced by the mitochondria hypotonic treatment or the inner membrane permeability transition. The saturation of the oxidation rate was observed as a function of mitochondrial protein concentration. This effect was shown to result from cytochrome c binding to the mitochondrial membranes. At a relatively high concentration of mitochondria, the oxidation rate was strongly activated by 4 mm Mg(2+) due to cytochrome c desorption from the membranes. A minimal kinetic model was developed to explain the main phenomena of the external NADH oxidation modulated by cytochrome c and Mg(2+) in mitochondria with the ruptured outer membrane. The computational behavior of the model closely agreed with the experimental data. We suggest that the redox state of the released cytochrome c, considered by other authors to be important for apoptosis, may strongly depend on its oxidation by the fraction of mitochondria with the ruptured outer membrane and on the cytoplasmic cytochrome c reductase activity.
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Affiliation(s)
- Victor V Lemeshko
- School of Physics, Science Department, National University of Colombia, Medellin Branch, AA3840 Medellin, Colombia, South America.
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