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McDonald J, von Spakovsky MR, Reynolds WT. Predicting Polymer Brush Behavior in Solvents Using the Steepest-Entropy-Ascent Quantum Thermodynamic Framework. J Phys Chem B 2023; 127:10370-10391. [PMID: 38006350 DOI: 10.1021/acs.jpcb.3c02713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2023]
Abstract
The steepest-entropy-ascent quantum thermodynamic (SEAQT) framework is utilized to study the effects of temperature on polymer brushes. The brushes are represented by a discrete energy spectrum, and energy degeneracies obtained through the replica-exchange Wang-Landau algorithm. The SEAQT equation of motion is applied to the density of states to establish a unique kinetic path from an initial thermodynamic state to a stable equilibrium state. The kinetic path describes the brush's evolution in state space, as it interacts with a thermal reservoir. The predicted occupation probabilities along the kinetic path are used to determine the expected thermodynamic and structural properties. The polymer density profile of a polystyrene brush in cyclohexane solvent is predicted using the equation of motion, and it agrees qualitatively with the experimental density profiles. The Flory-Huggins parameter chosen to describe brush-solvent interactions affects the solvent distribution in the brush but has a minimal impact on the polymer density profile. Three types of nonequilibrium kinetic paths with differing amounts of entropy production are considered: a heating path, a cooling path, and a heating-cooling path. Properties such as tortuosity, radius of gyration, brush density, solvent density, and brush chain conformations are calculated for each path.
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Affiliation(s)
- Jared McDonald
- Materials Science & Engineering Department, Virginia Tech, Blacksburg, Virginia 24061, United States
| | | | - William T Reynolds
- Materials Science & Engineering Department, Virginia Tech, Blacksburg, Virginia 24061, United States
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2
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Chino M, Di Costanzo LF, Leone L, La Gatta S, Famulari A, Chiesa M, Lombardi A, Pavone V. Designed Rubredoxin miniature in a fully artificial electron chain triggered by visible light. Nat Commun 2023; 14:2368. [PMID: 37185349 PMCID: PMC10130062 DOI: 10.1038/s41467-023-37941-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 04/06/2023] [Indexed: 05/17/2023] Open
Abstract
Designing metal sites into de novo proteins has significantly improved, recently. However, identifying the minimal coordination spheres, able to encompass the necessary information for metal binding and activity, still represents a great challenge, today. Here, we test our understanding with a benchmark, nevertheless difficult, case. We assemble into a miniature 28-residue protein, the quintessential elements required to fold properly around a FeCys4 redox center, and to function efficiently in electron-transfer. This study addresses a challenge in de novo protein design, as it reports the crystal structure of a designed tetra-thiolate metal-binding protein in sub-Å agreement with the intended design. This allows us to well correlate structure to spectroscopic and electrochemical properties. Given its high reduction potential compared to natural and designed FeCys4-containing proteins, we exploit it as terminal electron acceptor of a fully artificial chain triggered by visible light.
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Affiliation(s)
- Marco Chino
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 21, 80126, Napoli, Italy
| | - Luigi Franklin Di Costanzo
- Department of Agricultural Sciences, University of Naples Federico II, Via Università 100, 80055, Portici, Italy
| | - Linda Leone
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 21, 80126, Napoli, Italy
| | - Salvatore La Gatta
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 21, 80126, Napoli, Italy
| | - Antonino Famulari
- Department of Chemistry, University of Torino, Via Giuria 9, 10125, Torino, Italy
- Department of Condensed Matter Physics, University of Zaragoza, Calle Pedro Cerbuna 12, 50009, Zaragoza, Spain
| | - Mario Chiesa
- Department of Chemistry, University of Torino, Via Giuria 9, 10125, Torino, Italy
| | - Angela Lombardi
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 21, 80126, Napoli, Italy.
| | - Vincenzo Pavone
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 21, 80126, Napoli, Italy.
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3
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McDonald J, von Spakovsky MR, Reynolds WT. Predicting non-equilibrium folding behavior of polymer chains using the steepest-entropy-ascent quantum thermodynamic framework. J Chem Phys 2023; 158:104904. [PMID: 36922120 DOI: 10.1063/5.0137444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Abstract
The steepest-entropy-ascent quantum thermodynamic (SEAQT) framework is used to explore the influence of heating and cooling on polymer chain folding kinetics. The framework predicts how a chain moves from an initial non-equilibrium state to stable equilibrium along a unique thermodynamic path. The thermodynamic state is expressed by occupation probabilities corresponding to the levels of a discrete energy landscape. The landscape is generated using the Replica Exchange Wang-Landau method applied to a polymer chain represented by a sequence of hydrophobic and polar monomers with a simple hydrophobic-polar amino acid model. The chain conformation evolves as energy shifts among the levels of the energy landscape according to the principle of steepest entropy ascent. This principle is implemented via the SEAQT equation of motion. The SEAQT framework has the benefit of providing insight into structural properties under non-equilibrium conditions. Chain conformations during heating and cooling change continuously without sharp transitions in morphology. The changes are more drastic along non-equilibrium paths than along quasi-equilibrium paths. The SEAQT-predicted kinetics are fitted to rates associated with the experimental intensity profiles of cytochrome c protein folding with Rouse dynamics.
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Affiliation(s)
- Jared McDonald
- Materials Science and Engineering Department, Virginia Tech, Blacksburg, Virginia 24061, USA
| | | | - William T Reynolds
- Materials Science and Engineering Department, Virginia Tech, Blacksburg, Virginia 24061, USA
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4
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Characterization of oxidation of glutathione by cytochrome c. J Bioenerg Biomembr 2021; 54:1-8. [PMID: 34893948 PMCID: PMC8789735 DOI: 10.1007/s10863-021-09926-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 10/22/2021] [Indexed: 10/29/2022]
Abstract
Cytochrome c is a member of the respiratory chain of the mitochondria. Non-membrane-bound (free) cytochrome c can be reduced by gluthatione as well as ascorbic acid. We investigated the effect of pH, Ca2+, Mg2+ and anionic phospholipids on the reduction of cytochrome c by glutathione.The reduction of cytochrome c by thiols was measured using photometry. Mitochondrial oxygen consumption was detected by use of oxygen electrode. Glutathione does not reduce cytochrome c at pH = 7.0 in the absence of Ca2+ and Mg2+. The reduction of cytochrome c by glutathione is inhibited by anionic lipids, especially cardiolipin. The typical conditions of apoptosis-elevated pH, Ca2+ level and Mg2+-increases the reduction of cytochrome c. Glutathione (5 mM) causes increased mitochondrial O2 consumption at pH = 8.0, in the presence of ADP either 1 mM Mg2+ or 1 mM Ca2+. Our results suggest that membrane bound cyt c does not oxidize glutathione. Free (not membrane bound) cytochrome c can oxidize glutathione. In mitochondria, O2 is depleted only in the presence of ADP, so the O2 depletion observed in the presence of glutathione can be related to the respiratory chain. Decreased glutathione levels play a role in apoptosis. Therefore, membrane unbound cyt c can contribute to apoptosis by oxidation of glutathione.
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Nesci S, Trombetti F, Pagliarani A, Ventrella V, Algieri C, Tioli G, Lenaz G. Molecular and Supramolecular Structure of the Mitochondrial Oxidative Phosphorylation System: Implications for Pathology. Life (Basel) 2021; 11:242. [PMID: 33804034 PMCID: PMC7999509 DOI: 10.3390/life11030242] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 03/09/2021] [Accepted: 03/11/2021] [Indexed: 02/07/2023] Open
Abstract
Under aerobic conditions, mitochondrial oxidative phosphorylation (OXPHOS) converts the energy released by nutrient oxidation into ATP, the currency of living organisms. The whole biochemical machinery is hosted by the inner mitochondrial membrane (mtIM) where the protonmotive force built by respiratory complexes, dynamically assembled as super-complexes, allows the F1FO-ATP synthase to make ATP from ADP + Pi. Recently mitochondria emerged not only as cell powerhouses, but also as signaling hubs by way of reactive oxygen species (ROS) production. However, when ROS removal systems and/or OXPHOS constituents are defective, the physiological ROS generation can cause ROS imbalance and oxidative stress, which in turn damages cell components. Moreover, the morphology of mitochondria rules cell fate and the formation of the mitochondrial permeability transition pore in the mtIM, which, most likely with the F1FO-ATP synthase contribution, permeabilizes mitochondria and leads to cell death. As the multiple mitochondrial functions are mutually interconnected, changes in protein composition by mutations or in supercomplex assembly and/or in membrane structures often generate a dysfunctional cascade and lead to life-incompatible diseases or severe syndromes. The known structural/functional changes in mitochondrial proteins and structures, which impact mitochondrial bioenergetics because of an impaired or defective energy transduction system, here reviewed, constitute the main biochemical damage in a variety of genetic and age-related diseases.
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Affiliation(s)
- Salvatore Nesci
- Department of Veterinary Medical Sciences, Alma Mater Studiorum University of Bologna, 40064 Ozzano Emilia, Italy; (F.T.); (V.V.); (C.A.)
| | - Fabiana Trombetti
- Department of Veterinary Medical Sciences, Alma Mater Studiorum University of Bologna, 40064 Ozzano Emilia, Italy; (F.T.); (V.V.); (C.A.)
| | - Alessandra Pagliarani
- Department of Veterinary Medical Sciences, Alma Mater Studiorum University of Bologna, 40064 Ozzano Emilia, Italy; (F.T.); (V.V.); (C.A.)
| | - Vittoria Ventrella
- Department of Veterinary Medical Sciences, Alma Mater Studiorum University of Bologna, 40064 Ozzano Emilia, Italy; (F.T.); (V.V.); (C.A.)
| | - Cristina Algieri
- Department of Veterinary Medical Sciences, Alma Mater Studiorum University of Bologna, 40064 Ozzano Emilia, Italy; (F.T.); (V.V.); (C.A.)
| | - Gaia Tioli
- Department of Biomedical and Neuromotor Sciences, Alma Mater Studiorum University of Bologna, 40138 Bologna, Italy;
| | - Giorgio Lenaz
- Department of Biomedical and Neuromotor Sciences, Alma Mater Studiorum University of Bologna, 40138 Bologna, Italy;
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Wu M, Gu J, Zong S, Guo R, Liu T, Yang M. Research journey of respirasome. Protein Cell 2020; 11:318-338. [PMID: 31919741 PMCID: PMC7196574 DOI: 10.1007/s13238-019-00681-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Accepted: 12/11/2019] [Indexed: 12/11/2022] Open
Abstract
Respirasome, as a vital part of the oxidative phosphorylation system, undertakes the task of transferring electrons from the electron donors to oxygen and produces a proton concentration gradient across the inner mitochondrial membrane through the coupled translocation of protons. Copious research has been carried out on this lynchpin of respiration. From the discovery of individual respiratory complexes to the report of the high-resolution structure of mammalian respiratory supercomplex I1III2IV1, scientists have gradually uncovered the mysterious veil of the electron transport chain (ETC). With the discovery of the mammalian respiratory mega complex I2III2IV2, a new perspective emerges in the research field of the ETC. Behind these advances glitters the light of the revolution in both theory and technology. Here, we give a short review about how scientists 'see' the structure and the mechanism of respirasome from the macroscopic scale to the atomic scale during the past decades.
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Affiliation(s)
- Meng Wu
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Jinke Gu
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Shuai Zong
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Runyu Guo
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Tianya Liu
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Maojun Yang
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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7
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Schweitzer-Stenner R. Relating the multi-functionality of cytochrome c to membrane binding and structural conversion. Biophys Rev 2018; 10:1151-1185. [PMID: 29574621 PMCID: PMC6082307 DOI: 10.1007/s12551-018-0409-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 02/23/2018] [Indexed: 12/16/2022] Open
Abstract
Cytochrome c is known as an electron-carrying protein in the respiratory chain of mitochondria. Over the last 20 years, however, alternative functions of this very versatile protein have become the focus of research interests. Upon binding to anionic lipids such as cardiolipin, the protein acquires peroxidase activity. Multiple lines of evidence suggest that this requires a conformational change of the protein which involves partial unfolding of its tertiary structure. This review summarizes the current state of knowledge of how cytochrome c interacts with cardiolipin-containing surfaces and how this affects its structure and function. In this context, we delineate partially conflicting results regarding the affinity of cytochrome c binding to cardiolipin-containing liposomes of different size and its influence on the structure of the protein and the morphology of the membrane.
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8
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Lobo-Jarne T, Ugalde C. Respiratory chain supercomplexes: Structures, function and biogenesis. Semin Cell Dev Biol 2018; 76:179-190. [PMID: 28743641 PMCID: PMC5780262 DOI: 10.1016/j.semcdb.2017.07.021] [Citation(s) in RCA: 116] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 07/12/2017] [Accepted: 07/13/2017] [Indexed: 01/08/2023]
Abstract
Over the past sixty years, researchers have made outmost efforts to clarify the structural organization and functional regulation of the complexes that configure the mitochondrial respiratory chain. As a result, the entire composition of each individual complex is practically known and, aided by notable structural advances in mammals, it is now widely accepted that these complexes stablish interactions to form higher-order supramolecular structures called supercomplexes and respirasomes. The mechanistic models and players that regulate the function and biogenesis of such superstructures are still under intense debate, and represent one of the hottest topics of the mitochondrial research field at present. Noteworthy, understanding the pathways involved in the assembly and organization of respiratory chain complexes and supercomplexes is of high biomedical relevance because molecular alterations in these pathways frequently result in severe mitochondrial disorders. The purpose of this review is to update the structural, biogenetic and functional knowledge about the respiratory chain supercomplexes and assembly factors involved in their formation, with special emphasis on their implications in mitochondrial disease. Thanks to the integrated data resulting from recent structural, biochemical and genetic approaches in diverse biological systems, the regulation of the respiratory chain function arises at multiple levels of complexity.
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Affiliation(s)
- Teresa Lobo-Jarne
- Instituto de Investigación Hospital 12 de Octubre (i+12), Madrid 28041, Spain
| | - Cristina Ugalde
- Instituto de Investigación Hospital 12 de Octubre (i+12), Madrid 28041, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), U723, Madrid 28029, Spain.
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9
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Azimzadeh JB, Fabella BA, Kastan NR, Hudspeth AJ. Thermal Excitation of the Mechanotransduction Apparatus of Hair Cells. Neuron 2018; 97:586-595.e4. [PMID: 29395911 PMCID: PMC5805653 DOI: 10.1016/j.neuron.2018.01.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 12/13/2017] [Accepted: 01/03/2018] [Indexed: 12/21/2022]
Abstract
Although a hair bundle is normally deflected by mechanical stimuli, we found that irradiation of a hair cell from the bullfrog's sacculus with ultraviolet light causes rapid motion of the hair bundle toward its tall edge. This movement is associated with opening of mechanotransduction channels and disappears when tip links are disrupted. We localized the absorptive element responsible for the motion to the region directly below the hair bundle and measured an action spectrum similar to the absorption spectra of mitochondrial constituents. Temperature measurements revealed heating around the site of absorption; direct heating of the hair bundle confirmed that the response to light is mediated through heat. Although mechanical offsets of the hair bundle revealed that heat softens gating springs, it also acts directly to open transduction channels. This study identifies an unconventional method of hair-cell stimulation and clarifies the previously unexplained sensitivity of auditory organs to thermal stimulation.
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Affiliation(s)
- Julien B Azimzadeh
- Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA; Laboratory of Sensory Neuroscience, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Brian A Fabella
- Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA; Laboratory of Sensory Neuroscience, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Nathaniel R Kastan
- Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA; Laboratory of Sensory Neuroscience, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - A J Hudspeth
- Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA; Laboratory of Sensory Neuroscience, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
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10
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Malyshka D, Schweitzer-Stenner R. Photoreduction of ferricytochrome c in the presence of potassium ferrocyanide. Photochem Photobiol Sci 2018; 17:1462-1468. [DOI: 10.1039/c8pp00286j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ferricytochrome c has been previously shown to photoreduce in the presence of ferrocyanide anions, but the process has been poorly understood.
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11
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Femnou AN, Kuzmiak-Glancy S, Covian R, Giles AV, Kay MW, Balaban RS. Intracardiac light catheter for rapid scanning transmural absorbance spectroscopy of perfused myocardium: measurement of myoglobin oxygenation and mitochondria redox state. Am J Physiol Heart Circ Physiol 2017; 313:H1199-H1208. [PMID: 28939647 DOI: 10.1152/ajpheart.00306.2017] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 09/05/2017] [Accepted: 09/19/2017] [Indexed: 11/22/2022]
Abstract
Absorbance spectroscopy of intrinsic cardiac chromophores provides nondestructive assessment of cytosolic oxygenation and mitochondria redox state. Isolated perfused heart spectroscopy is usually conducted by collecting reflected light from the heart surface, which represents a combination of surface scattering events and light that traversed portions of the myocardium. Reflectance spectroscopy with complex surface scattering effects in the beating heart leads to difficulty in quantitating chromophore absorbance. In this study, surface scattering was minimized and transmural path length optimized by placing a light source within the left ventricular chamber while monitoring transmurally transmitted light at the epicardial surface. The custom-designed intrachamber light catheter was a flexible coaxial cable (2.42-Fr) terminated with an encapsulated side-firing LED of 1.8 × 0.8 mm, altogether similar in size to a Millar pressure catheter. The LED catheter had minimal impact on aortic flow and heart rate in Langendorff perfusion and did not impact stability of the left ventricule of the working heart. Changes in transmural absorbance spectra were deconvoluted using a library of chromophore reference spectra to quantify the relative contribution of specific chromophores to the changes in measured absorbance. This broad-band spectral deconvolution approach eliminated errors that may result from simple dual-wavelength absorbance intensity. The myoglobin oxygenation level was only 82.2 ± 3.0%, whereas cytochrome c and cytochrome a + a3 were 13.3 ± 1.4% and 12.6 ± 2.2% reduced, respectively, in the Langendorff-perfused heart. The intracardiac illumination strategy permits transmural optical absorbance spectroscopy in perfused hearts, which provides a noninvasive real-time monitor of cytosolic oxygenation and mitochondria redox state.NEW & NOTEWORTHY Here, a novel nondestructive real-time approach for monitoring intrinsic indicators of cardiac metabolism and oxygenation is described using a catheter-based transillumination of the left ventricular free wall together with complete spectral analysis of transmitted light. This approach is a significant improvement in the quality of cardiac optical absorbance spectroscopic metabolic analyses.
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Affiliation(s)
- Armel N Femnou
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland; and.,Department of Biomedical Engineering, The George Washington University, Washington, District of Columbia
| | - Sarah Kuzmiak-Glancy
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland; and.,Department of Biomedical Engineering, The George Washington University, Washington, District of Columbia
| | - Raul Covian
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland; and
| | - Abigail V Giles
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland; and
| | - Matthew W Kay
- Department of Biomedical Engineering, The George Washington University, Washington, District of Columbia
| | - Robert S Balaban
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland; and
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12
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Abstract
Respiratory chain dysfunction plays an important role in human disease and aging. It is now well established that the individual respiratory complexes can be organized into supercomplexes, and structures for these macromolecular assemblies, determined by electron cryo-microscopy, have been described recently. Nevertheless, the reason why supercomplexes exist remains an enigma. The widely held view that they enhance catalysis by channeling substrates is challenged by both structural and biophysical information. Here, we evaluate and discuss data and hypotheses on the structures, roles, and assembly of respiratory-chain supercomplexes and propose a future research agenda to address unanswered questions.
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Affiliation(s)
- Dusanka Milenkovic
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Strasse 9b, 50931 Cologne, Germany
| | - James N Blaza
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK
| | - Nils-Göran Larsson
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Strasse 9b, 50931 Cologne, Germany; Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden.
| | - Judy Hirst
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK.
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13
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Pelster LN, Minteer SD. Mitochondrial Inner Membrane Biomimic for the Investigation of Electron Transport Chain Supercomplex Bioelectrocatalysis. ACS Catal 2016. [DOI: 10.1021/acscatal.6b00950] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Lindsey N. Pelster
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Shelley D. Minteer
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
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14
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Functional role of mitochondrial respiratory supercomplexes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:427-43. [DOI: 10.1016/j.bbabio.2013.11.002] [Citation(s) in RCA: 224] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 10/30/2013] [Accepted: 11/02/2013] [Indexed: 12/30/2022]
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15
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Respiratory supercomplexes: structure, function and assembly. Protein Cell 2013; 4:582-90. [PMID: 23828195 DOI: 10.1007/s13238-013-3032-y] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2013] [Accepted: 05/23/2013] [Indexed: 12/11/2022] Open
Abstract
The mitochondrial respiratory chain consists of 5 enzyme complexes that are responsible for ATP generation. The paradigm of the electron transport chain as discrete enzymes diffused in the inner mitochondrial membrane has been replaced by the solid state supercomplex model wherein the respiratory complexes associate with each other to form supramolecular complexes. Defects in these supercomplexes, which have been shown to be functionally active and required for forming stable respiratory complexes, have been associated with many genetic and neurodegenerative disorders demonstrating their biomedical significance. In this review, we will summarize the functional and structural significance of supercomplexes and provide a comprehensive review of their assembly and the assembly factors currently known to play a role in this process.
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16
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Gómez LA, Hagen TM. Age-related decline in mitochondrial bioenergetics: does supercomplex destabilization determine lower oxidative capacity and higher superoxide production? Semin Cell Dev Biol 2012; 23:758-67. [PMID: 22521482 DOI: 10.1016/j.semcdb.2012.04.002] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Revised: 03/31/2012] [Accepted: 04/04/2012] [Indexed: 12/17/2022]
Abstract
Mitochondrial decay plays a central role in the aging process. Although certainly multifactorial in nature, defective operation of the electron transport chain (ETC) constitutes a key mechanism involved in the age-associated loss of mitochondrial energy metabolism. Primarily, mitochondrial dysfunction affects the aging animal by limiting bioenergetic reserve capacity and/or increasing oxidative stress via enhanced electron leakage from the ETC. Even though the important aging characteristics of mitochondrial decay are known, the molecular events underlying inefficient electron flux that ultimately leads to higher superoxide appearance and impaired respiration are not completely understood. This review focuses on the potential role(s) that age-associated destabilization of the macromolecular organization of the ETC (i.e. supercomplexes) may be important for development of the mitochondrial aging phenotype, particularly in post-mitotic tissues.
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Affiliation(s)
- Luis A Gómez
- Linus Pauling Institute, Oregon State University, Corvallis, OR 97331, USA
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17
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Kim N, Ripple MO, Springett R. Measurement of the mitochondrial membrane potential and pH gradient from the redox poise of the hemes of the bc1 complex. Biophys J 2012; 102:1194-203. [PMID: 22404942 DOI: 10.1016/j.bpj.2012.02.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Revised: 01/22/2012] [Accepted: 02/02/2012] [Indexed: 11/18/2022] Open
Abstract
The redox potentials of the hemes of the mitochondrial bc(1) complex are dependent on the proton-motive force due to the energy transduction. This allows the membrane potential and pH gradient components to be calculated from the oxidation state of the hemes measured with multi-wavelength cell spectroscopy. Oxidation states were measured in living RAW 264.7 cells under varying electron flux and membrane potential obtained by a combination of oligomycin and titration with a proton ionophore. A stochastic model of bc(1) turnover was used to confirm that the membrane potential and redox potential of the ubiquinone pool could be measured from the redox poise of the b-hemes under physiological conditions assuming the redox couples are in equilibrium. The pH gradient was then calculated from the difference in redox potentials of cytochrome c and ubiquinone pool using the stochastic model to evaluate the ΔG of the bc(1) complex. The technique allows absolute quantification of the membrane potential, pH gradient, and proton-motive force without the need for genetic manipulation or exogenous compounds.
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Affiliation(s)
- N Kim
- Department of Radiology, Dartmouth Medical School, Hanover, New Hampshire, USA
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Gorgoglione V, Palmitessa V, Lofrumento DD, La Piana G, Abbrescia DI, Marzulli D, Lofrumento NE. Ceramide-induced activation of cytosolic NADH/cytochrome c electron transport pathway: An additional source of energy for apoptosis. Arch Biochem Biophys 2010; 504:210-20. [PMID: 20850412 DOI: 10.1016/j.abb.2010.09.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Revised: 09/10/2010] [Accepted: 09/10/2010] [Indexed: 11/26/2022]
Abstract
We have investigated whether increase in the oxidation rate of exogenous cytochrome c (cyto-c), induced by long-chain ceramides, might be due to an increased rate of cytosolic NADH/cyto-c electron transport pathway. This process was identified in isolated liver mitochondria and has been studied in our laboratory for many years. Data from highly specific test of sulfite oxidase prove that exogenous cyto-c both in the absence and presence of ceramide cannot permeate through the mitochondrial outer membrane. However, the oxidation of added NADH, mediated by exogenous cyto-c and coupled to the generation of a membrane potential supporting the ATP synthesis, can also be stimulated by ceramide. The results obtained suggest that ceramide molecules, by increasing mitochondrial permeability, with the generation of either raft-like platforms or channels, may have a dual function. They can promote the release of endogenous cyto-c and activate, with an energy conserving process, the oxidation of cytosolic NADH either inducing the formation of new respiratory contact sites or increasing the frequency of the pre-existing porin contact sites. In agreement with the data in the literature, an increase of mitochondrial ceramide molecules level may represent an efficient strategy to activate and support the correct execution of apoptotic program.
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Lenaz G, Genova ML. Structure and organization of mitochondrial respiratory complexes: a new understanding of an old subject. Antioxid Redox Signal 2010; 12:961-1008. [PMID: 19739941 DOI: 10.1089/ars.2009.2704] [Citation(s) in RCA: 186] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The enzymatic complexes of the mitochondrial respiratory chain have been extensively investigated in their structural and functional properties. A clear distinction is possible today between three complexes in which the difference in redox potential allows proton translocation (complexes I, III, and IV) and those having the mere function to convey electrons to the respiratory chain. We also have a clearer understanding of the structure and function of most respiratory complexes, of their biogenesis and regulation, and of their capacity to generate reactive oxygen species. Past investigations led to the conclusion that the complexes are randomly dispersed and functionally connected by diffusion of smaller redox components, coenzyme Q and cytochrome c. More-recent investigations by native gel electrophoresis and single-particle image processing showed the existence of supramolecular associations. Flux-control analysis demonstrated that complexes I and III in mammals and I, III, and IV in plants kinetically behave as single units, suggesting the existence of substrate channeling. This review discusses conditions affecting the formation of supercomplexes that, besides kinetic advantage, have a role in the stability and assembly of the individual complexes and in preventing excess oxygen radical formation. Disruption of supercomplex organization may lead to functional derangements responsible for pathologic changes.
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Affiliation(s)
- Giorgio Lenaz
- Dipartimento di Biochimica "G. Moruzzi," Alma Mater Studiorum, Università di Bologna, Bologna, Italy.
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20
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Dejean LM, Ryu SY, Martinez-Caballero S, Teijido O, Peixoto PM, Kinnally KW. MAC and Bcl-2 family proteins conspire in a deadly plot. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1231-8. [PMID: 20083086 DOI: 10.1016/j.bbabio.2010.01.007] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Revised: 01/06/2010] [Accepted: 01/09/2010] [Indexed: 12/31/2022]
Abstract
Apoptosis is an elemental form of programmed cell death; it is fundamental to higher eukaryotes and essential to mechanisms controlling tissue homeostasis. Apoptosis is also involved in many pathologies including cancer, neurodegenerative diseases, aging, and infarcts. This cell death program is tightly regulated by Bcl-2 family proteins by controlling the formation of the mitochondrial apoptosis-induced channel or MAC. Assembly of MAC corresponds to permeabilization of the mitochondrial outer membrane, which is the so called commitment step of apoptosis. MAC provides the pathway through the mitochondrial outer membrane for the release of cytochrome c and other pro-apoptotic factors from the intermembrane space. While overexpression of anti-apoptotic Bcl-2 eliminates MAC activity, oligomers of the pro-apoptotic members Bax and/or Bak are essential structural component(s) of MAC. Assembly of MAC from Bax or Bak was monitored in real time by directly patch-clamping mitochondria with micropipettes containing the sentinel tBid, a direct activator of Bax and Bak. Herein, a variety of high affinity inhibitors of MAC (iMAC) that may prove to be crucial tools in mechanistic studies have recently been identified. This review focuses on characterization of MAC activity, its regulation by Bcl-2 family proteins, and a discussion of how MAC can be pharmacologically turned on or off depending on the pathology to be treated.
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Affiliation(s)
- Laurent M Dejean
- Department Basic Sci., 345 East 24th St., New York University, College of Dentistry, New York, NY 10010, USA
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21
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22
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Lenaz G, Genova ML. Structural and functional organization of the mitochondrial respiratory chain: a dynamic super-assembly. Int J Biochem Cell Biol 2009; 41:1750-1772. [PMID: 19711505 DOI: 10.1016/j.biocel.2009.04.003] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The structural organization of the mitochondrial oxidative phosphorylation (OXPHOS) system has received large attention in the past and most investigations led to the conclusion that the respiratory enzymatic complexes are randomly dispersed in the lipid bilayer of the inner membrane and functionally connected by fast diffusion of smaller redox components, Coenzyme Q and cytochrome c. More recent investigations by native gel electrophoresis, however, have shown the existence of supramolecular associations of the respiratory complexes, confirmed by electron microscopy analysis and single particle image processing. Flux control analysis has demonstrated that Complexes I and III in mammalian mitochondria and Complexes I, III, and IV in plant mitochondria kinetically behave as single units with control coefficients approaching unity for each single component, suggesting the existence of substrate channelling within the supercomplexes. The reasons why the presence of substrate channelling for Coenzyme Q and cytochrome c was overlooked in the past are analytically discussed. The review also discusses the forces and the conditions responsible for the formation of the supramolecular units. The function of the supercomplexes appears not to be restricted to kinetic advantages in electron transfer: we discuss evidence on their role in the stability and assembly of the individual complexes and in preventing excess oxygen radical formation. Finally, there is increasing evidence that disruption of the supercomplex organization leads to functional derangements responsible for pathological changes.
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Affiliation(s)
- Giorgio Lenaz
- Dipartimento di Biochimica G. Moruzzi, Università di Bologna, Via Irnerio 48, 40126 Bologna, Italy.
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23
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Supramolecular organization of ATP synthase and respiratory chain in mitochondrial membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:672-80. [DOI: 10.1016/j.bbabio.2008.12.016] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2008] [Revised: 12/29/2008] [Accepted: 12/29/2008] [Indexed: 01/05/2023]
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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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Fee JA, Case DA, Noodleman L. Toward a chemical mechanism of proton pumping by the B-type cytochrome c oxidases: application of density functional theory to cytochrome ba3 of Thermus thermophilus. J Am Chem Soc 2008; 130:15002-21. [PMID: 18928258 DOI: 10.1021/ja803112w] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A mechanism for proton pumping by the B-type cytochrome c oxidases is presented in which one proton is pumped in conjunction with the weakly exergonic, two-electron reduction of Fe-bound O 2 to the Fe-Cu bridging peroxodianion and three protons are pumped in conjunction with the highly exergonic, two-electron reduction of Fe(III)- (-)O-O (-)-Cu(II) to form water and the active oxidized enzyme, Fe(III)- (-)OH,Cu(II). The scheme is based on the active-site structure of cytochrome ba 3 from Thermus thermophilus, which is considered to be both necessary and sufficient for coupled O 2 reduction and proton pumping when appropriate gates are in place (not included in the model). Fourteen detailed structures obtained from density functional theory (DFT) geometry optimization are presented that are reasonably thought to occur during the four-electron reduction of O 2. Each proton-pumping step takes place when a proton resides on the imidazole ring of I-His376 and the large active-site cluster has a net charge of +1 due to an uncompensated, positive charge formally associated with Cu B. Four types of DFT were applied to determine the energy of each intermediate, and standard thermochemical approaches were used to obtain the reaction free energies for each step in the catalytic cycle. This application of DFT generally conforms with previously suggested criteria for a valid model (Siegbahn, P. E. M.; Blomberg, M. A. R. Chem. Rev. 2000, 100, 421-437) and shows how the chemistry of O 2 reduction in the heme a 3 -Cu B dinuclear center can be harnessed to generate an electrochemical proton gradient across the lipid bilayer.
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Affiliation(s)
- James A Fee
- The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
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26
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Collman JP, Decréau RA. Functional biomimetic models for the active site in the respiratory enzyme cytochrome c oxidase. Chem Commun (Camb) 2008:5065-76. [PMID: 18956030 DOI: 10.1039/b808070b] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A functional analog of the active site in the respiratory enzyme, cytochrome c oxidase (CcO) reproduces every feature in CcO's active site: a myoglobin-like heme (heme a3), a distal tridentate imidazole copper complex (Cu(B)), a phenol (Tyr244), and a proximal imidazole. When covalently attached to a liquid-crystalline SAM film on an Au electrode, this functional model continuously catalyzes the selective four-electron reduction of dioxygen at physiological potential and pH, under rate-limiting electron flux (as occurs in CcO).
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Affiliation(s)
- James P Collman
- Stanford University, Chemistry Department, Stanford, CA-94305-5080, USA.
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27
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Monge C, Beraud N, Kuznetsov AV, Rostovtseva T, Sackett D, Schlattner U, Vendelin M, Saks VA. Regulation of respiration in brain mitochondria and synaptosomes: restrictions of ADP diffusion in situ, roles of tubulin, and mitochondrial creatine kinase. Mol Cell Biochem 2008; 318:147-65. [PMID: 18629616 DOI: 10.1007/s11010-008-9865-7] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Accepted: 06/25/2008] [Indexed: 11/25/2022]
Abstract
The role of ubiquitous mitochondrial creatine kinase (uMtCK) reaction in regulation of mitochondrial respiration was studied in purified preparations of rat brain synaptosomes and mitochondria. In permeabilized synaptosomes, apparent Km for exogenous ADP, Km (ADP), in regulation of respiration in situ was rather high (110 +/- 11 microM) in comparison with isolated brain mitochondria (9 +/- 1 microM). This apparent Km for ADP observed in isolated mitochondria in vitro dramatically increased to 169 +/- 52 microM after their incubation with 1 muM of dimeric tubulin showing that in rat brain, particularly in synaptosomes, mitochondrial outer membrane permeability for ADP, and ATP may be restricted by tubulin binding to voltage dependent anion channel (VDAC). On the other hand, in synaptosomes apparent Km (ADP) decreased to 25 +/- 1 microM in the presence of 20 mM creatine. To fully understand this effect of creatine on kinetics of respiration regulation, complete kinetic analysis of uMtCK reaction in isolated brain mitochondria was carried out. This showed that oxidative phosphorylation specifically altered only the dissociation constants for MgATP, by decreasing that from ternary complex MtCK.Cr.MgATP (K (a)) from 0.13 +/- 0.02 to 0.018 +/- 0.007 mM and that from binary complex MtCK.MgATP (K (ia)) from 1.1 +/- 0.29 mM to 0.17 +/- 0.07 mM. Apparent decrease of dissociation constants for MgATP reflects effective cycling of ATP and ADP between uMtCK and adenine nucleotide translocase (ANT). These results emphasize important role and various pathophysiological implications of the phosphocreatine-creatine kinase system in energy transfer in brain cells, including synaptosomes.
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Affiliation(s)
- Claire Monge
- Laboratory of Fundamental and Applied Bioenergetics, Joseph Fourier University, Grenoble, France
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28
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Christenson E, Merlin S, Saito M, Schlesinger P. Cholesterol effects on BAX pore activation. J Mol Biol 2008; 381:1168-83. [PMID: 18590739 DOI: 10.1016/j.jmb.2008.06.037] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Revised: 06/11/2008] [Accepted: 06/13/2008] [Indexed: 01/29/2023]
Abstract
The importance of BCL-2 family proteins in the control of cell death has been clearly established. One of the key members of this family, BAX, has soluble, membrane-bound, and membrane-integrated forms that are central to the regulation of apoptosis. Using purified monomeric human BAX, defined liposomes, and isolated human mitochondria, we have characterized the soluble to membrane transition and pore formation by this protein. For the purified protein, activation, but not oligomerization, is required for membrane binding. The transition to the membrane environment includes a binding step that is reversible and distinct from the membrane integration step. Oligomerization and pore activation occur after the membrane integration. In cells, BAX targets several intracellular membranes but notably does not target the plasma membrane while initiating apoptosis. When cholesterol was added to either the liposome bilayer or mitochondrial membranes, we observed increased binding but markedly reduced integration of BAX into both membranes. This cholesterol inhibition of membrane integration accounts for the reduction of BAX pore activation in liposomes and mitochondrial membranes. Our results indicate that the presence of cholesterol in membranes inhibits the pore-forming activity of BAX by reducing the ability of BAX to transition from a membrane-associated protein to a membrane-integral protein.
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Affiliation(s)
- Eric Christenson
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA
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29
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Collman JP, Devaraj NK, Decréau RA, Yang Y, Yan YL, Ebina W, Eberspacher TA, Chidsey CED. A cytochrome C oxidase model catalyzes oxygen to water reduction under rate-limiting electron flux. Science 2007; 315:1565-8. [PMID: 17363671 PMCID: PMC3064436 DOI: 10.1126/science.1135844] [Citation(s) in RCA: 366] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
We studied the selectivity of a functional model of cytochrome c oxidase's active site that mimics the coordination environment and relative locations of Fe(a3), Cu(B), and Tyr(244). To control electron flux, we covalently attached this model and analogs lacking copper and phenol onto self-assembled monolayer-coated gold electrodes. When the electron transfer rate was made rate limiting, both copper and phenol were required to enhance selective reduction of oxygen to water. This finding supports the hypothesis that, during steady-state turnover, the primary role of these redox centers is to rapidly provide all the electrons needed to reduce oxygen by four electrons, thus preventing the release of toxic partially reduced oxygen species.
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Affiliation(s)
- James P. Collman
- To whom correspondence should be addressed. (J.P.C.); (C.E.D.C.)
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30
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Lesnefsky EJ, Hoppel CL. Oxidative phosphorylation and aging. Ageing Res Rev 2006; 5:402-33. [PMID: 16831573 DOI: 10.1016/j.arr.2006.04.001] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2006] [Revised: 04/01/2006] [Accepted: 04/04/2006] [Indexed: 10/24/2022]
Abstract
This review addresses the data that support the presence and contribution of decreased mitochondrial oxidative phosphorylation during aging to impaired cellular metabolism. Aging impairs substrate oxidation, decreases cellular energy production and increases the production of reactive intermediates that are toxic to the cell. First, the basic principles of mitochondrial oxidative physiology are briefly reviewed. Second, the focus on the relationship of altered mitochondrial respiration to the increased production of reactive oxygen species that are employed by the "rate of living" and the "uncoupling to survive" theories of aging are discussed. Third, the impairment of function of respiration in aging is reviewed using an organ-based approach in mammalian systems. Fourth, the current state of knowledge regarding aging-induced alterations in the composition and function of key mitochondrial constituents is addressed. Model organisms, including C. elegans and D. melanogaster are included where pertinent. Fifth, these defects are related to knowledge regarding the production of reactive oxygen species from specific sites of the electron transport chain.
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Affiliation(s)
- Edward J Lesnefsky
- Department of Medicine, Division of Cardiology, Case Western Reserve University, Cleveland, OH, USA
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31
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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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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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Dejean LM, Martinez-Caballero S, Kinnally KW. Is MAC the knife that cuts cytochrome c from mitochondria during apoptosis? Cell Death Differ 2006; 13:1387-95. [PMID: 16676005 DOI: 10.1038/sj.cdd.4401949] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Apoptosis is a phenomenon fundamental to higher eukaryotes and essential to mechanisms controlling tissue homeostasis. Bcl-2 family proteins tightly control this cell death program by regulating the permeabilization of the mitochondrial outer membrane and, hence, the release of cytochrome c and other proapoptotic factors. Mitochondrial apoptosis-induced channel (MAC) is the mitochondrial apoptosis-induced channel and is responsible for cytochrome c release early in apoptosis. MAC activity is detected by patch clamping mitochondria at the time of cytochrome c release. The Bcl-2 family proteins regulate apoptosis by controlling the formation of MAC. Depending on cell type and apoptotic inducer, Bax and/or Bak are structural component(s) of MAC. Overexpression of the antiapoptotic protein Bcl-2 eliminates MAC activity. The focus of this review is a biophysical characterization of MAC activity and its regulation by Bcl-2 family proteins, and ends with some discussion of therapeutic targets.
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Affiliation(s)
- L M Dejean
- Department of Basic Sciences, College of Dentistry, New York University, NY 10010, USA
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Chen Q, Lesnefsky EJ. Depletion of cardiolipin and cytochrome c during ischemia increases hydrogen peroxide production from the electron transport chain. Free Radic Biol Med 2006; 40:976-82. [PMID: 16540393 DOI: 10.1016/j.freeradbiomed.2005.10.043] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2005] [Revised: 10/04/2005] [Accepted: 10/19/2005] [Indexed: 10/25/2022]
Abstract
Mitochondrial electron transport is a major source of reactive oxygen species (ROS) during cardiac ischemia and reperfusion. In the isolated rabbit heart, 30 and 45 min of ischemia decrease the contents of cardiolipin and cytochrome c in subsarcolemmal mitochondria (SSM) located beneath the plasma membrane. In contrast, interfibrillar mitochondria (IFM) in the interior of the myocyte do not sustain a decrease in cardiolipin. We proposed that the depletion of cardiolipin and the accompanying cytochrome c loss during ischemia were critical events that amplified ROS production by mitochondria. The total production of H2O2 was measured in submitochondrial particles (SMP) prepared from rabbit heart SSM and IFM after 0, 15, 30, and 45 min of ischemia. With NADH as substrate, total H2O2 production was increased only in SMP from SSM after 30 and 45 min ischemia, when ischemia decreased the content of cardiolipin and cytochrome c. In contrast, ischemia did not augment H2O2 generation in SMP from IFM with preserved cardiolipin and cytochrome c content. Thus, during the evolution of ischemic injury, H2O2 production from the electron transport chain increased after depletion of cardiolipin and the loss of cytochrome c.
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Affiliation(s)
- Qun Chen
- Department of Medicine, Division of Cardiology, Case Western Reserve University, Cleveland, OH 44106, USA
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35
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Guiral M, Leroy G, Bianco P, Gallice P, Guigliarelli B, Bruschi M, Nitschke W, Giudici-Orticoni MT. Interaction and electron transfer between the high molecular weight cytochrome and cytochrome c3 from Desulfovibrio vulgaris Hildenborough: Kinetic, microcalorimetric, EPR and electrochemical studies. Biochim Biophys Acta Gen Subj 2005; 1723:45-54. [PMID: 15780995 DOI: 10.1016/j.bbagen.2005.01.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2004] [Revised: 01/27/2005] [Accepted: 01/28/2005] [Indexed: 11/26/2022]
Abstract
The complex formation between the tetraheme cytochrome c3 and hexadecaheme high molecular weight cytochrome c (Hmc), the structure of which has recently been resolved, has been characterized by cross-linking experiments, EPR, electrochemistry and kinetic analysis, and some key parameters of the interaction were determined. The analysis of electron transfer between [Fe] hydrogenase, cytochrome c3 and Hmc demonstrates a redox-shuttling role of cytochrome c3 in the pathway from hydrogenase to Hmc, and shows an effect of redox state on the interaction between the two cytochromes. The role of polyheme cytochromes in electron transfer from periplasmic hydrogenase to membrane redox proteins is assessed. A model with cytochrome c3 as an intermediate between hydrogenase and various polyheme cytochromes is proposed and its physiological consequences are discussed.
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Affiliation(s)
- Marianne Guiral
- Bioénergétique et Ingénierie des Protéines, CNRS, IBSM, 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
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36
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Bertrand P. Application of electron transfer theories to biological systems. STRUCTURE AND BONDING 2005. [DOI: 10.1007/3-540-53260-9_1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
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37
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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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Audi SH, Bongard RD, Dawson CA, Siegel D, Roerig DL, Merker MP. Duroquinone reduction during passage through the pulmonary circulation. Am J Physiol Lung Cell Mol Physiol 2003; 285:L1116-31. [PMID: 12882764 DOI: 10.1152/ajplung.00185.2003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The lungs can substantially influence the redox status of redox-active plasma constituents. Our objective was to examine aspects of the kinetics and mechanisms that determine pulmonary disposition of redox-active compounds during passage through the pulmonary circulation. Experiments were carried out on rat and mouse lungs with 2,3,5,6-tetramethyl-1,4-benzoquinone [duroquinone (DQ)] as a model amphipathic quinone reductase substrate. We measured DQ and durohydroquinone (DQH2) concentrations in the lung venous effluent after injecting, or while infusing, DQ or DQH2 into the pulmonary arterial inflow. The maximum net rates of DQ reduction to DQH2 in the rat and mouse lungs were approximately 4.9 and 2.5 micromol. min(-1).g dry lung wt(-1), respectively. The net rate was apparently the result of freely permeating access of DQ and DQH2 to tissue sites of redox reactions, dominated by dicumarol-sensitive DQ reduction to DQH2 and cyanide-sensitive DQH2 reoxidation back to DQ. The dicumarol sensitivity along with immunodetectable expression of NAD(P)H-quinone oxidoreductase 1 (NQO1) in the rat lung tissue suggest cytoplasmic NQO1 as the dominant site of DQ reduction. The effect of cyanide on DQH2 oxidation suggests that the dominant site of oxidation is complex III of the mitochondrial electron transport chain. If one envisions DQ as a model compound for examining the disposition of amphipathic NQO1 substrates in the lungs, the results are consistent with a role for lung NQO1 in determining the redox status of such compounds in the circulation. For DQ, the effect is conversion of a redox-cycling, oxygen-activating quinone into a stable hydroquinone.
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Affiliation(s)
- Said H Audi
- Department of Biomedical Engineering, Marquette University, Milwaukee, Wisconsin 53201, USA.
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Schägger H. Respiratory chain supercomplexes of mitochondria and bacteria. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1555:154-9. [PMID: 12206908 DOI: 10.1016/s0005-2728(02)00271-2] [Citation(s) in RCA: 278] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Respiratory chain complexes are fragments of larger structural and functional units, the respiratory chain supercomplexes or "respirasomes", which exist in bacterial and mitochondrial membranes. Supercomplexes of mitochondria and bacteria contain complexes III, IV, and complex I, with the notable exception of Saccharomyces cerevisiae, which does not possess complex I. These supercomplexes often are stable to sonication but sensitive to most detergents except digitonin. In S. cerevisiae, a major component linking complexes III and IV together is cardiolipin.In Paracoccus denitrificans, complex I itself is rather detergent-sensitive and thus could not be obtained in detergent-solubilized form so far. However, it can be isolated as part of a supercomplex. Stabilization of complex I by binding to complex III was also found in human mitochondria. Further functional roles of the organization in a supercomplex are catalytic enhancement by reducing diffusion distances of substrates or, depending on the organism, channelling of the substrates quinone and cytochrome c. This makes redox reactions less dependent of midpoint potentials of substrates, and permits electron flow at low degree of substrate reduction.A dimeric state of ATP synthase seems to be specific for mitochondria. Exclusively, monomeric ATP synthase was found in Acetobacterium woodii, in P. denitrificans, and in spinach chloroplasts.
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Affiliation(s)
- Hermann Schägger
- Biochemie I, Zentrum der Biologischen Chemie, Universitätsklinikum Frankfurt, Theodor-Stern-Kai 7, Haus 25B, D-60590 Frankfort on the Main, Germany.
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Ramachandran A, Moellering DR, Ceaser E, Shiva S, Xu J, Darley-Usmar V. Inhibition of mitochondrial protein synthesis results in increased endothelial cell susceptibility to nitric oxide-induced apoptosis. Proc Natl Acad Sci U S A 2002; 99:6643-8. [PMID: 12011428 PMCID: PMC124456 DOI: 10.1073/pnas.102019899] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mutations in mitochondrial DNA, affecting the activity of respiratory complexes, have been implicated in many chronic degenerative diseases. Mitochondrial proteins coded for by both the mitochondrial and nuclear genes are known to have important signaling roles in apoptosis. However, the impact of the inhibition of mitochondrial protein synthesis on apoptosis is largely unknown. This inhibition is particularly important in NO-dependent cytotoxicity, which is believed to have a significant mitochondrial component and depend on other factors such as glycolysis. In this study we have examined whether the inhibition of mitochondrial protein synthesis by chloramphenicol increases the susceptibility of endothelial cells to undergo NO-dependent apoptosis in glucose-free media. Bovine aortic endothelial cells were treated with chloramphenicol, which resulted in a decreased ratio of mitochondrial complex IV to cytochrome c and increased oxidant production in the cell. Inhibition of mitochondrial protein synthesis was associated with a greater susceptibility of the cells to apoptosis induced by NO in glucose-free medium.
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Affiliation(s)
- Anup Ramachandran
- Department of Pathology, University of Alabama, Birmingham, AL 35294, USA
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41
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Jayanthi S, Lewis BD, Cadet JL. Fas-induced apoptosis of glioma cells is associated with down-regulation of the hSCO1 protein, a subunit of complex IV. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2001; 91:131-6. [PMID: 11457500 DOI: 10.1016/s0169-328x(01)00138-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
ApoI/Fas belongs to the tumor necrosis factor receptor (TNFR) superfamily and mediates cell death in various cell types. Earlier studies from this laboratory have shown that Fas-mediated cell death of glioma cells occur, in part, through the production of reactive oxygen species (ROS). To further dissect the molecular mechanisms that are involved in Fas-induced cell death, we compared gene expression between Fas-treated and saline-treated human neuroglioma H4 cells by using the technique of mRNA differential display. This approach led to the identification of hSCO1, a component of the inner mitochondrial membrane, which is required for the correct assembly, and catalytic function of cytochrome-c oxidase, as a Fas down-regulated gene. The decrease in hSCO1 mRNA expression was time-dependent, becoming most prominent after 4 h of Fas-treatment. Morphological changes observed by confocal microscopy revealed that after 4 h of Fas-treatment, the cells undergo membrane blebbing and early formation of apoptotic bodies. These observations are discussed in terms of their support for an important role of mitochondrial events in Fas-induced apoptosis.
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Affiliation(s)
- S Jayanthi
- Molecular Neuropsychiatry Section, NIDA-IRP, National Institutes of Health, 5500 Nathan Shock Drive, Baltimore, MD 21224, USA
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42
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Pinheiro TJ, Cheng H, Seeholzer SH, Roder H. Direct evidence for the cooperative unfolding of cytochrome c in lipid membranes from H-(2)H exchange kinetics. J Mol Biol 2000; 303:617-26. [PMID: 11054296 DOI: 10.1006/jmbi.2000.4159] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The interaction of cytochrome c (cyt c) with anionic lipid membranes is known to disrupt the tightly packed native structure of the protein. This process leads to a lipid-inserted denatured state, which retains a native-like alpha-helical structure but lacks any specific tertiary interactions. The structural and dynamic properties of cyt c bound to vesicles containing an anionic phospholipid (DOPS) were investigated by amide H-(2)H exchange using two-dimensional NMR spectroscopy and electrospray ionisation mass spectrometry. The H-(2)H exchange kinetics of the core amide protons in cyt c, which in the native protein undergo exchange via an uncorrelated EX2 mechanism, exchange in the lipid vesicles via a highly concerted global transition that exposes these protected amide groups to solvent. The lack of pH dependence and the observation of distinct populations of deuterated and protonated species by mass spectrometry confirms that exchange occurs via an EX1 mechanism with a common rate of 1(+/-0.5) h(-1), which reflects the rate of transition from the lipid-inserted state, H(l), to an unprotected conformation, D(i), associated with the lipid interface.
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Affiliation(s)
- T J Pinheiro
- Department of Biological Sciences, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK.
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Sanghera N, Pinheiro TJ. Unfolding and refolding of cytochrome c driven by the interaction with lipid micelles. Protein Sci 2000; 9:1194-202. [PMID: 10892811 PMCID: PMC2144667 DOI: 10.1110/ps.9.6.1194] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Binding of native cyt c to L-PG micelles leads to a partially unfolded conformation of cyt c. This micelle-bound state has no stable tertiary structure, but remains as alpha-helical as native cyt c in solution. In contrast, binding of the acid-unfolded cyt c to L-PG micelles induces folding of the polypeptide, resulting in a similar helical state to that originated from the binding of native cyt c to L-PG micelles. Far-ultraviolet (UV) circular dichroism (CD) spectra showed that this common micelle-associated helical state (HL) has a native-like alpha-helix content, but is highly expanded without a tightly packed hydrophobic core, as revealed by tryptophan fluorescence, near-UV, and Soret CD spectroscopy. The kinetics of the interaction of native and acid-unfolded cyt c was investigated by stopped-flow tryptophan fluorescence. Formation of H(L) from the native state requires the disruption of the tightly packed hydrophobic core in the native protein. This micelle-induced unfolding of cyt c occurs at a rate approximately 0.1 s(-1), which is remarkably faster in the lipid environment compared with the expected rate of unfolding in solution. Refolding of acid-unfolded cyt c with L-PG micelles involves an early highly helical collapsed state formed during the burst phase (<3 ms), and the observed main kinetic event reports on the opening of this early compact intermediate prior to insertion into the lipid micelle.
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Affiliation(s)
- N Sanghera
- Department of Biological Sciences, University of Warwick, Coventry, United Kingdom
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Krab K, Wagner MJ, Wagner AM, Moller IM. Identification of the site where the electron transfer chain of plant mitochondria is stimulated by electrostatic charge screening. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:869-76. [PMID: 10651825 DOI: 10.1046/j.1432-1327.2000.01065.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Modular kinetic analysis was used to determine the sites in plant mitochondria where charge-screening stimulates the rate of electron transfer from external NAD(P)H to oxygen. In mitochondria isolated from potato (Solanum tuberosum L.) tuber callus, stimulation of the rate of oxygen uptake was accompanied by a decrease in the steady-state reduction level of coenzyme Q, and by a small decrease in the steady-state reduction level of cytochrome c. Modular kinetic analysis around coenzyme Q revealed that stimulation of the rate was due to stimulation of quinol oxidation via the cytochrome pathway (cytochrome bc1, cytochrome c and cytochrome c oxidase). It was not a consequence of any effect on quinone reduction (by external NADH or NADPH dehydrogenase). This explains the salt-induced decrease in the steady-state reduction level of coenzyme Q. Analysis around cytochrome c revealed that stimulation by salts was due to a dual effect on the respiratory chain. The kinetic curves for the oxidation and reduction pathways of cytochrome c revealed that they were both activated by salt, the simultaneity explaining the small variation observed in the steady-state reduction level of cytochrome c. A simple kinetic core model is used to show that changes in the rate of dissociation of cytochrome c from the membrane can explain the observed kinetic changes in both cytochrome c reduction and cytochrome c oxidation. The stimulation is proposed to be the result of an increase in the rate constant of cytochrome c dissociation from the membrane induced by cation screening. We conclude that this type of modular kinetic analysis is a powerful tool to identify and quantitatively characterize multiple-site effects on the mitochondrial respiratory chain.
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Affiliation(s)
- K Krab
- Department of Molecular Cell Physiology, BioCentrum Amsterdam, Faculty of Biology, Vrije Universiteit, Amsterdam, The Netherlands.
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45
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Yan Z, Booth FW. Cytochrome c promoter activity in soleus and white vastus lateralis muscles in rats. J Appl Physiol (1985) 1998; 85:973-8. [PMID: 9729572 DOI: 10.1152/jappl.1998.85.3.973] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cytochrome c protein and mRNA are 300 and 100% higher, respectively, in the soleus muscle (predominantly slow-twitch oxidative) than the white vastus lateralis (predominately fast-twitch glycolytic) muscle (W. W. Winder, K. M. Baldwin, and J. O. Holloszy. Eur. J. Biochem. 47: 461-467, 1974; M. M. Lai and F. W. Booth. J. Appl. Physiol. 69: 843-848, 1990). However, the mechanisms controlling these differences in cytochrome c mRNA are largely unknown. The present study employed direct plasmid injection techniques to determine whether the proximal promoter (-726 to +610) of the rat somatic cytochrome c gene was more active in the soleus than in white vastus lateralis muscles in rats. No difference between the soleus and white vastus lateralis muscles for the activities of the -726, -631, -489, -326, -215, -159 and -149 cytochrome c promoters was noted. The results of this study suggest that additional elements (outside of -726 to +610) in the cytochrome c gene may be required, or posttranscriptional regulation may account, for the higher cytochrome c mRNA in the slow-twitch oxidative muscle.
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MESH Headings
- Animals
- Cytochrome c Group/genetics
- Cytochrome c Group/physiology
- Female
- Gene Expression Regulation, Enzymologic/genetics
- Gene Expression Regulation, Enzymologic/physiology
- Luciferases
- Muscle Fibers, Fast-Twitch/enzymology
- Muscle Fibers, Fast-Twitch/physiology
- Muscle Fibers, Slow-Twitch/enzymology
- Muscle Fibers, Slow-Twitch/physiology
- Muscle, Skeletal/enzymology
- Muscle, Skeletal/physiology
- Plasmids/genetics
- Plasmids/physiology
- Promoter Regions, Genetic/physiology
- RNA, Messenger/biosynthesis
- Rats
- Rats, Sprague-Dawley
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Affiliation(s)
- Z Yan
- Department of Integrative Biology, Pharmacology, and Physiology, University of Texas Medical School, Houston, Texas, 77030, USA
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Boumans H, Grivell LA, Berden JA. The respiratory chain in yeast behaves as a single functional unit. J Biol Chem 1998; 273:4872-7. [PMID: 9478928 DOI: 10.1074/jbc.273.9.4872] [Citation(s) in RCA: 137] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Inhibitor titrations using antimycin have been used to study the pool behavior of ubiquinone and cytochrome c in the respiratory chain of the yeast Saccharomyces cerevisiae. If present in a homogeneous pool, these carriers should be able to diffuse freely through or along the membrane respectively and accept and subsequently donate electrons to an infinite number of the respective respiratory complex. However, we show that under physiological conditions neither ubiquinone nor cytochrome c exhibits pool behavior, implying that the respiratory chain in yeast is one functional unit. Pool behavior can be introduced for both small carriers by adding chaotropic agents to the reaction medium. We conclude that these agents disrupt the interaction between the respiratory complexes, thereby causing them to become randomly arranged in the membrane. In such a situation, ubiquinone and cytochrome c become mobile carriers, shuttling between the large respiratory complexes. Furthermore, we conclude from the respiratory activities found for different substrates that the respiratory units in yeast vary in composition with respect to the ubiquinone reducing enzyme. All units contain the cytochrome chain, supplemented with either succinate dehydrogenase or the internal or the external NADH dehydrogenase. This implies that when only one substrate is available, only a certain fraction of the cytochrome chain is used in respiration. The molecular organization of the respiratory chain in yeast is compared with that of higher eukaryotes and to the electron transfer systems of photosynthetic membranes. Differences between the organization of the respiratory chain of yeast and that of higher eukaryotes are discussed in terms of the ability of yeast to radically alter its metabolism in response to change of the available carbon source.
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Affiliation(s)
- H Boumans
- E. C. Slater Institute, Department of Molecular Cell Biology, BioCentrum, University of Amsterdam, 1018 TV Amsterdam, The Netherlands
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47
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Yan Z, Salmons S, Dang YI, Hamilton MT, Booth FW. Increased contractile activity decreases RNA-protein interaction in the 3'-UTR of cytochrome c mRNA. THE AMERICAN JOURNAL OF PHYSIOLOGY 1996; 271:C1157-66. [PMID: 8897821 DOI: 10.1152/ajpcell.1996.271.4.c1157] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
This study was designed to gain an insight into mechanisms by which cytochrome c gene expression is enhanced by increased contractile activity in skeletal muscle. When rat tibialis anterior muscles were stimulated (10 Hz, 0.25 ms) for 0, 2, 6, 12, or 24 h or 2, 5, 9, or 13 days (n = 4 for each time point), cytochrome c protein (enzyme-linked immunosorbent assay) and mRNA (Northern blot analysis) concentrations started to increase by 9 days, and this was associated with concurrent decreases in cytochrome c mRNA-protein interaction (RNA gel mobility shift assay). We found that the decreased RNA-protein interaction in the stimulated muscle extract was restored by ultracentrifugation (150,000 g, 1 h) in the supernatant fraction. The 150,000 g pellet fraction of stimulated muscle was capable of inhibiting the RNA-protein interaction in control tibialis anterior muscles. These results provide evidence of an inhibitory factor that is responsible for decreasing RNA-protein interaction in the 3'-untranslated region of cytochrome c mRNA in continuously stimulated muscle.
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Affiliation(s)
- Z Yan
- Department of Integrative Biology, University of Texas Medical School, Houston 77225, USA
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48
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Bergling S. Diffusion influenced binary reactive processes in membranes involving identical particles: a Monte Carlo study. Biophys Chem 1995; 56:227-39. [PMID: 17023326 DOI: 10.1016/0301-4622(95)00037-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/1994] [Accepted: 02/15/1995] [Indexed: 10/17/2022]
Abstract
Simple random walk simulations on triangular lattices were performed in order to obtain a basic quantitative understanding of the kinetics of diffusion influenced binary reactive processes of membrane associated peptides or proteins within the two dimensionality of lipid bilayers. The results of the Monte Carlo simulations are compared with various formal approximate steady-state approaches, such as presented by Keizer [Acc. Chem. Res., 18 (1985) 235-241] in the context of statistical nonequilibrium thermodynamics or by Hardt [Biophys. Chem., 10 (1979) 239-243], based on the well known work of Delbrück and Adam. For diffusion controlled binary reactions of identical particles, nice agreement with the numerically simulated values is found in the low concentration limit for both Hardt's and Keizer's approach. For the latter a fluctuating steady-state particle source has to be considered. The dependence of the steady-state rate coefficient on system size is investigated, and the results are compared to the work of Swartz and Peacock-López [J. Chem. Phys., 95 (4) (1991) 2727-2731]. In order to elucidate the results, a practical application is considered. An application to a dimerization reaction on vesicles of typical experimental dimensions is given.
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Affiliation(s)
- S Bergling
- Biocenter of the University of Basel, Klingelbergstr. 70, CH-4056 Basel, Switzerland
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49
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Cortese JD, Voglino AL, Hackenbrock CR. Persistence of cytochrome c binding to membranes at physiological mitochondrial intermembrane space ionic strength. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1228:216-228. [PMID: 7893728 DOI: 10.1016/0005-2728(94)00178-8] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We have shown that cytochrome c (cyt c) diffuses primarily in three dimensions in the intermembrane space (IMS) of intact mitochondria at physiological ionic strength (I). Recently, we found that a small percentage (11.2 +/- 2.1%) of endogenous cyt c remains bound to inner mitochondrial membranes (IMM) at high, physiological I (I = 150 mM), even after extensive washing with solutions at physiological I, overnight dialysis, changes in medium osmolarity, or further purification of IMM at high I using self-generating Percoll gradients. Measurements of heme c/heme a ratios, and electron transport (ET) reactions in which cyt c participates, confirmed the presence of a low amount of this I-resistant, membrane-bound form of cyt c (MB-cyt c), that had one third of the ET activity of electrostatically-bound cyt c (EB-cyt c), and which could not account for maximal ET rates. The amount of MB-cyt c was significantly increased above endogenous MB-cyt c by exposing KCl-washed IMM to increasing concentrations of exogenous cyt c. Also, subjecting large unilamellar vesicles (LUV) to successive cycles of cyt c binding/high I KCl-washes gave progressive increases in MB-cyt c. These protocols allowed in vitro characterization of MB-cyt c. The I at which binding takes place affects the affinity of cyt c for membranes, and oxidized cyt c had a greater intrinsic affinity for IMM or SUV than reduced cyt c. MB-cyt c appears to be bound partially by hydrophobic interactions since MB-cyt c was detected on negatively charged (asolectin) LUV and also on neutral, zwitterionic (phosphatidylcholine) LUV at high I. Consistent with the concentration-dependent changes in MB-cyt c, decreasing the IMS-volume of intact mitochondria (i.e., increasing th endogenous IMS-cyt c concentration) by metabolic or osmotic means increased the amount of MB-cyt c. After cyt c was delivered into the IMS by liposome-mediated low pH-induced fusion, resonance energy transfer showed a time-dependent cyt c-membrane proximity which was consistent with slow exchange of soluble IMS-entrapped cyt c molecules with a population bound to membranes at I = 150 mM. We conclude that, even though the majority of functional IMS-cyt c diffuses in three dimensions, a small portion remains firmly bound on the surface of the IMM under I conditions that are physiological for intact mitochondria. The occurrence of MB-cyt c may reflect an intrinsic conformational flexibility in cyt c, that allows a degree of membrane penetration and the formation of hydrophobic interactions which stabilize the membrane-bound form. The persistence of cyt c-membrane interactions under physiological I conditions indicates that cyt c-mediated ET in the IMS involves both fast (3D-diffusion) and slow (2D-diffusion) pathways for electron transfer.
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Affiliation(s)
- J D Cortese
- Department of Cell Biology and Anatomy, School of Medicine, University of North Carolina, Chapel Hill, 27599-7090, USA
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50
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Krähenbühl S, Talos C, Fischer S, Reichen J. Toxicity of bile acids on the electron transport chain of isolated rat liver mitochondria. Hepatology 1994; 19:471-9. [PMID: 7904981 DOI: 10.1002/hep.1840190228] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The toxicity of hydrophilic (cholate) and lipophilic (deoxycholate, chenodeoxycholate, and lithocholate) bile acids on the function of the electron transport chain was investigated in intact and disrupted rat liver mitochondria. In intact mitochondria, lipophilic bile acids used at a concentration of 100 mumol/L (0.1 mumol/mg protein) inhibited state 3 and state 3u (dinitrophenol-uncoupled) oxidation rates for L-glutamate, succinate, duroquinol or ascorbate/N,N,N',N'-tetramethyl-p-phenylenediamine as substrates. In contrast, state 4 oxidation rates and ADP/oxygen ratios were not significantly affected. At a bile acid concentration of 10 mumol/L (0.01 mumol/mg protein), the state 3 oxidation rate for L-glutamate was decreased in the presence of deoxycholate, chenodeoxycholate or lithocholate, whereas only lithocholate inhibited state 3 oxidation for succinate or duroquinol. In broken mitochondria, inhibition of oxidative metabolism was found for NADH or duroquinol as substrate in the presence of 100 mumol/L lithocholate (0.2 mumol/mg protein) and for duroquinol in the presence of 100 mumol/L chenodeoxycholate. Direct assessment of the activities of the enzyme complexes of the electron transport chain revealed decreased activities of complex I and complex III in the presence of 100 mumol/L deoxycholate or chenodeoxycholate or 10 mumol/L lithocholate. Inhibition of complex IV required higher bile acid concentrations (300 mumol/L for chenodeoxycholate or 30 mumol/L for lithocholate), and complex II was not affected. Both chenodeoxycholate and lithocholate were incorporated into mitochondrial membranes. The phospholipid content of mitochondrial membranes decreased in incubations containing 100 mumol/L (0.1 mumol/mg protein) chenodeoxycholate but was not affected in the presence of 100 mumol/L lithocholate.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- S Krähenbühl
- Department of Medicine, University of Berne, Switzerland
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