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Bellanti F, Villani R, Tamborra R, Blonda M, Iannelli G, di Bello G, Facciorusso A, Poli G, Iuliano L, Avolio C, Vendemiale G, Serviddio G. Synergistic interaction of fatty acids and oxysterols impairs mitochondrial function and limits liver adaptation during nafld progression. Redox Biol 2018; 15:86-96. [PMID: 29220698 PMCID: PMC5725223 DOI: 10.1016/j.redox.2017.11.016] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 11/07/2017] [Accepted: 11/18/2017] [Indexed: 02/08/2023] Open
Abstract
The complete mechanism accounting for the progression from simple steatosis to steatohepatitis in nonalcoholic fatty liver disease (NAFLD) has not been elucidated. Lipotoxicity refers to cellular injury caused by hepatic free fatty acids (FFAs) and cholesterol accumulation. Excess cholesterol autoxidizes to oxysterols during oxidative stress conditions. We hypothesize that interaction of FAs and cholesterol derivatives may primarily impair mitochondrial function and affect biogenesis adaptation during NAFLD progression. We demonstrated that the accumulation of specific non-enzymatic oxysterols in the liver of animals fed high-fat+high-cholesterol diet induces mitochondrial damage and depletion of proteins of the respiratory chain complexes. When tested in vitro, 5α-cholestane-3β,5,6β-triol (triol) combined to FFAs was able to reduce respiration in isolated liver mitochondria, induced apoptosis in primary hepatocytes, and down-regulated transcription factors involved in mitochondrial biogenesis. Finally, a lower protein content in the mitochondrial respiratory chain complexes was observed in human non-alcoholic steatohepatitis. In conclusion, hepatic accumulation of FFAs and non-enzymatic oxysterols synergistically facilitates development and progression of NAFLD by impairing mitochondrial function, energy balance and biogenesis adaptation to chronic injury.
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Affiliation(s)
- Francesco Bellanti
- C.U.R.E. University Centre for Liver Disease Research and Treatment, Institute of Internal Medicine, Department of Medical and Surgical Sciences, University of Foggia, 71122 Foggia, Italy
| | - Rosanna Villani
- C.U.R.E. University Centre for Liver Disease Research and Treatment, Institute of Internal Medicine, Department of Medical and Surgical Sciences, University of Foggia, 71122 Foggia, Italy
| | - Rosanna Tamborra
- C.U.R.E. University Centre for Liver Disease Research and Treatment, Institute of Internal Medicine, Department of Medical and Surgical Sciences, University of Foggia, 71122 Foggia, Italy
| | - Maria Blonda
- C.U.R.E. University Centre for Liver Disease Research and Treatment, Institute of Internal Medicine, Department of Medical and Surgical Sciences, University of Foggia, 71122 Foggia, Italy; Institute of Neurology, Department of Medical and Surgical Sciences, University of Foggia, 71122 Foggia, Italy
| | - Giuseppina Iannelli
- C.U.R.E. University Centre for Liver Disease Research and Treatment, Institute of Internal Medicine, Department of Medical and Surgical Sciences, University of Foggia, 71122 Foggia, Italy
| | - Giorgia di Bello
- C.U.R.E. University Centre for Liver Disease Research and Treatment, Institute of Internal Medicine, Department of Medical and Surgical Sciences, University of Foggia, 71122 Foggia, Italy
| | - Antonio Facciorusso
- C.U.R.E. University Centre for Liver Disease Research and Treatment, Institute of Internal Medicine, Department of Medical and Surgical Sciences, University of Foggia, 71122 Foggia, Italy
| | - Giuseppe Poli
- Department of Clinical and Biological Sciences, University of Torino at San Luigi Gonzaga Hospital, 10043 Orbassano, Torino, Italy
| | - Luigi Iuliano
- Laboratory of Vascular Biology and Mass Spectrometry, Department of Medico-Surgical Sciences and Biotechnologies, Sapienza University of Rome, 04100 Latina, Italy
| | - Carlo Avolio
- Institute of Neurology, Department of Medical and Surgical Sciences, University of Foggia, 71122 Foggia, Italy
| | - Gianluigi Vendemiale
- C.U.R.E. University Centre for Liver Disease Research and Treatment, Institute of Internal Medicine, Department of Medical and Surgical Sciences, University of Foggia, 71122 Foggia, Italy
| | - Gaetano Serviddio
- C.U.R.E. University Centre for Liver Disease Research and Treatment, Institute of Internal Medicine, Department of Medical and Surgical Sciences, University of Foggia, 71122 Foggia, Italy.
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2
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Papa S, Capitanio G, Papa F. The mechanism of coupling between oxido-reduction and proton translocation in respiratory chain enzymes. Biol Rev Camb Philos Soc 2017. [DOI: 10.1111/brv.12347] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Sergio Papa
- Department of Basic Medical Sciences, Neurosciences and Sense Organs (BMSNSO), Section of Medical Biochemistry; University of Bari ‘Aldo Moro’; Piazza G. Cesare 11 70124 Bari Italy
- Institute of Biomembranes and Bioenergetics; National Research Council at BMSNSO; Piazza G. Cesare 11 70124 Bari Italy
| | - Giuseppe Capitanio
- Department of Basic Medical Sciences, Neurosciences and Sense Organs (BMSNSO), Section of Medical Biochemistry; University of Bari ‘Aldo Moro’; Piazza G. Cesare 11 70124 Bari Italy
| | - Francesco Papa
- Department of Basic Medical Sciences, Neurosciences and Sense Organs (BMSNSO), Section of Medical Biochemistry; University of Bari ‘Aldo Moro’; Piazza G. Cesare 11 70124 Bari Italy
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3
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Bellanti F, Mirabella L, Mitarotonda D, Blonda M, Tamborra R, Cinnella G, Fersini A, Ambrosi A, Dambrosio M, Vendemiale G, Serviddio G. Propofol but not sevoflurane prevents mitochondrial dysfunction and oxidative stress by limiting HIF-1α activation in hepatic ischemia/reperfusion injury. Free Radic Biol Med 2016; 96:323-33. [PMID: 27154980 DOI: 10.1016/j.freeradbiomed.2016.05.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2016] [Revised: 04/16/2016] [Accepted: 05/01/2016] [Indexed: 02/05/2023]
Abstract
Mitochondrial dysfunction, reactive oxygen species (ROS) production and oxidative stress during reperfusion are determinant in hepatic ischemia/reperfusion (I/R) injury but may be impacted by different anesthetic agents. Thus, we aimed at comparing the effects of inhaled sevoflurane or intravenous propofol anesthesia on liver mitochondria in a rodent model of hepatic I/R injury. To this, male Wistar rats underwent I/R surgery using sevoflurane or propofol. In the I/R model, propofol limited the raise in serum aminotransferase levels as compared to sevoflurane. Mitochondrial oxygen uptake, respiratory activity, membrane potential and proton leak were altered in I/R; however, this impairment was significantly prevented by propofol but not sevoflurane. In addition, differently from sevoflurane, propofol limited hepatic I/R-induced mitochondria H2O2 production rate, free radical leak and hydroxynonenal-protein adducts levels. The I/R group anesthetized with propofol also showed a better recovery of hepatic ATP homeostasis and conserved integrity of mitochondrial PTP. Moreover, hypoxia-inducible factor 1 alpha (HIF-1α) expression was limited in such group. By using a cell model of desferoxamine-dependent HIF activation, we demonstrated that propofol was able to inhibit apoptosis and mitochondrial depolarization associated to HIF-1α action. In conclusion, hepatic I/R injury induces mitochondrial dysfunction that is not prevented by inhaled sevoflurane. On the contrary, propofol reduces liver damage and mitochondrial dysfunction by preserving respiratory activity, membrane potential and energy homeostasis, and limiting free radicals production as well as PTP opening. These hepatoprotective effects may involve the inhibition of HIF-1α.
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Affiliation(s)
- Francesco Bellanti
- C.U.R.E. University Centre for Liver Disease Research and Treatment, Institute of Internal Medicine, Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy.
| | - Lucia Mirabella
- Department of Anesthesia and Intensive Care, University of Foggia, Foggia, Italy
| | - Domenica Mitarotonda
- C.U.R.E. University Centre for Liver Disease Research and Treatment, Institute of Internal Medicine, Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
| | - Maria Blonda
- C.U.R.E. University Centre for Liver Disease Research and Treatment, Institute of Internal Medicine, Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
| | - Rosanna Tamborra
- C.U.R.E. University Centre for Liver Disease Research and Treatment, Institute of Internal Medicine, Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
| | - Gilda Cinnella
- Department of Anesthesia and Intensive Care, University of Foggia, Foggia, Italy
| | - Alberto Fersini
- Department of General Surgery, University of Foggia, Foggia, Italy
| | - Antonio Ambrosi
- Department of General Surgery, University of Foggia, Foggia, Italy
| | - Michele Dambrosio
- Department of Anesthesia and Intensive Care, University of Foggia, Foggia, Italy
| | - Gianluigi Vendemiale
- C.U.R.E. University Centre for Liver Disease Research and Treatment, Institute of Internal Medicine, Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
| | - Gaetano Serviddio
- C.U.R.E. University Centre for Liver Disease Research and Treatment, Institute of Internal Medicine, Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
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4
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Bellanti F, Romano AD, Giudetti AM, Rollo T, Blonda M, Tamborra R, Vendemiale G, Serviddio G. Many faces of mitochondrial uncoupling during age: damage or defense? J Gerontol A Biol Sci Med Sci 2013; 68:892-902. [PMID: 23292290 DOI: 10.1093/gerona/gls332] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
An increased mitochondrial proton leak occurs in aging, but the origin of such modification remains unclear. This study defined the cause of mitochondrial uncoupling in mitotic (liver) and postmitotic (heart) rat tissues during aging and its effects on energy homeostasis and free radical production. Proton leak in old heart mitochondria was dependent on uncoupling proteins' upregulation, whereas it was caused by alterations in the mitochondrial membrane composition in old liver. ATP homeostasis was impaired in both tissues from old animals and was associated to disrupted F0F1-ATPase activity. H2O2 production rate and 4-hydroxy-2-nonenalprotein adducts were higher in old liver mitochondria compared with young liver mitochondria, but they were similar in heart mitochondria from both groups. Moreover, key mitochondrial biogenesis regulators were upregulated in old liver but downregulated in old heart. In conclusion, uncoupling proteins mediate proton leak and avoid oxidative damage in heart, acting as a protective mechanism. This does not occur in liver, where ATP depletion and oxidative stress may stimulate mitochondrial biogenesis and eliminate damaged cells.
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Affiliation(s)
- Francesco Bellanti
- Dipartimento di Scienze Mediche e Chirurgiche, Università di Foggia 71122, Foggia, Italy.
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5
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Xie HY, Liu Q, Li JH, Fan LY, Cao CX. Model creation of moving redox reaction boundary in agarose gel electrophoresis by traditional potassium permanganate method. Analyst 2013; 138:1137-40. [DOI: 10.1039/c2an36373a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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6
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Serviddio G, Bellanti F, Giudetti AM, Gnoni GV, Capitanio N, Tamborra R, Romano AD, Quinto M, Blonda M, Vendemiale G, Altomare E. Mitochondrial oxidative stress and respiratory chain dysfunction account for liver toxicity during amiodarone but not dronedarone administration. Free Radic Biol Med 2011; 51:2234-42. [PMID: 21971348 DOI: 10.1016/j.freeradbiomed.2011.09.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Revised: 09/01/2011] [Accepted: 09/01/2011] [Indexed: 02/05/2023]
Abstract
The role played by oxidative stress in amiodarone-induced mitochondrial toxicity is debated. Dronedarone shows pharmacological properties similar to those of amiodarone but several differences in terms of toxicity. In this study, we analyzed the effects of the two drugs on liver mitochondrial function by administering an equivalent human dose to a rat model. Amiodarone increased mitochondrial H(2)O(2) synthesis, which in turn induced cardiolipin peroxidation. Moreover, amiodarone inhibited Complex I activity and uncoupled oxidative phosphorylation, leading to a reduction in the hepatic ATP content. We also observed a modification of membrane phospholipid composition after amiodarone administration. N-acetylcysteine completely prevented such effects. Although dronedarone shares with amiodarone the capacity to induce uncoupling of oxidative phosphorylation, it did not show any of the oxidative effects and did not impair mitochondrial bioenergetics. Our data provide important insights into the mechanism of mitochondrial toxicity induced by amiodarone. These results may greatly influence the clinical application and toxicity management of these two antiarrhythmic drugs.
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Affiliation(s)
- Gaetano Serviddio
- CURE Center for Liver Disease Research and Treatment, Institute of Internal Medicine, Department of Medical and Occupational Sciences, University of Foggia, 71122 Foggia, Italy.
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7
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Inhibition of proton pumping in membrane reconstituted bovine heart cytochrome c oxidase by zinc binding at the inner matrix side. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1807:1075-82. [DOI: 10.1016/j.bbabio.2011.05.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Revised: 05/13/2011] [Accepted: 05/16/2011] [Indexed: 11/23/2022]
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8
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Capitanio G, Martino PL, Capitanio N, Papa S. Redox Bohr effects and the role of heme a in the proton pump of bovine heart cytochrome c oxidase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1807:1287-94. [PMID: 21320464 DOI: 10.1016/j.bbabio.2011.02.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Revised: 01/25/2011] [Accepted: 02/05/2011] [Indexed: 10/18/2022]
Abstract
Structural and functional observations are reviewed which provide evidence for a central role of redox Bohr effect linked to the low-spin heme a in the proton pump of bovine heart cytochrome c oxidase. Data on the membrane sidedness of Bohr protons linked to anaerobic oxido-reduction of the individual metal centers in the liposome reconstituted oxidase are analysed. Redox Bohr protons coupled to anaerobic oxido-reduction of heme a (and Cu(A)) and Cu(B) exhibit membrane vectoriality, i.e. protons are taken up from the inner space upon reduction of these centers and released in the outer space upon their oxidation. Redox Bohr protons coupled to anaerobic oxido-reduction of heme a(3) do not, on the contrary, exhibit vectorial nature: protons are exchanged only with the outer space. A model of the proton pump of the oxidase, in which redox Bohr protons linked to the low-spin heme a play a central role, is described. This article is part of a Special Issue entitled: Allosteric cooperativity in respiratory proteins.
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9
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Mitochondrial respiratory dysfunction in familiar parkinsonism associated with PINK1 mutation. Neurochem Res 2008; 33:2565-74. [PMID: 18473170 DOI: 10.1007/s11064-008-9729-2] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2008] [Accepted: 04/23/2008] [Indexed: 10/22/2022]
Abstract
In the present study mitochondrial respiratory function of fibroblasts from a patient affected by early-onset parkinsonism carrying the homozygous W437X nonsense mutation in the PINK1 gene has been thoroughly characterized. When compared with normal fibroblasts, the patient's fibroblast mitochondria exhibited a lower respiratory activity and a decreased respiratory control ratio with cellular ATP supply relying mainly on enhanced glycolytic production. The quantity, specific activity and subunit pattern of the oxidative phosphorylation complexes were normal. However, a significant decrease of the cellular cytochrome c content was observed and this correlated with a reduced cytochrome c oxidase in situ-activity. Measurement of ROS revealed in mitochondria of the patient's fibroblasts enhanced O(2)(*-) and H(2)O(2) production abrogated by inhibition of complex I. No change in the glutathione-based redox buffering was, however, observed.
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10
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Grubina R, Basu S, Tiso M, Kim-Shapiro DB, Gladwin MT. Nitrite Reductase Activity of Hemoglobin S (Sickle) Provides Insight into Contributions of Heme Redox Potential Versus Ligand Affinity. J Biol Chem 2008; 283:3628-3638. [DOI: 10.1074/jbc.m705222200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
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11
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Enguita FJ, Pohl E, Turner DL, Santos H, Carrondo MA. Structural evidence for a proton transfer pathway coupled with haem reduction of cytochrome c″ from Methylophilus methylotrophus. J Biol Inorg Chem 2005; 11:189-96. [PMID: 16341897 DOI: 10.1007/s00775-005-0065-6] [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: 07/25/2005] [Accepted: 11/11/2005] [Indexed: 11/29/2022]
Abstract
The crystal structures of the oxidized and reduced forms of cytochrome c" from Methylophilus methylotrophus were solved from X-ray synchrotron data to atomic resolution. The overall fold of the molecule in the two redox states is very similar and is comparable to that of the oxygen-binding protein from the purple phototrophic bacterium Rhodobacter sphaeroides. However, significant modifications occur near the haem group, in particular the detachment from axial binding of His95 observed upon reduction as well as the adoption of different conformations of some protonatable residues that form a possible proton path from the haem pocket to the protein surface. These changes are associated with the previously well characterized redox-Bohr behaviour of this protein. Furthermore they provide a model for one of the presently proposed mechanisms of proton translocation in the much more complex protein cytochrome c oxidase.
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Affiliation(s)
- Francisco J Enguita
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, P.O. Box 127, 2781-901 Oeiras, Portugal
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12
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Blankman JI, Shahzad N, Miller CJ, Guiles RD. Direct voltammetric investigation of the electrochemical properties of human hemoglobin: relevance to physiological redox chemistry. Biochemistry 2000; 39:14806-12. [PMID: 11101296 DOI: 10.1021/bi000731b] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Voltammetric measurements on solutions of human hemoglobin using gold electrodes modified with omega-hydroxyalkanethiols have yielded the first direct measure of the reorganization energy of the protein. The value obtained based on extrapolation of the experimentally measured currents, 0.76 eV, is independent of pH (i.e., over the physiologically relevant rage, pH 6.8-7.4) and is remarkably similar to values obtained for myoglobin. This result is perhaps surprising given the marked dependence of the measured reduction potential of hemoglobin on pH (i.e., the redox Bohr effect). Electron transfer rates from the electrode to hemoglobin were also measured. Using similarly measured heterogeneous electron-transfer rates for cytochrome b(5), it is possible to predict the magnitude of the homogeneous electron-transfer rate from cytochrome b(5) to methemoglobin using a formalism developed by Marcus. These predicted rates are in reasonable agreement with reported rates of this physiological reaction based on stopped-flow kinetics experiments. These results suggest that the intrinsic electroreactivity of these heme proteins is sufficient to account for physiologically observed rates. Residual differences between homogeneous phase kinetics and those predicted by heterogeneous phase reactions are suggested to be due to small reductions in the outer-sphere reorganization energy of both component proteins which arise due to solvent exclusion at the interface between the two proteins in complex.
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Affiliation(s)
- J I Blankman
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
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13
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Papa S, Capitanio N, Villani G, Capitanio G, Bizzoca A, Palese LL, Carlino V, De Nitto E. Cooperative coupling and role of heme a in the proton pump of heme-copper oxidases. Biochimie 1998; 80:821-36. [PMID: 9893941 DOI: 10.1016/s0300-9084(00)88877-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the last few years, evidence has accumulated supporting the applicability of the cooperative model of proton pumps in cytochrome systems, vectorial Bohr mechanisms, to heme-copper oxidases. The vectorial Bohr mechanism is based on short- and long-range protonmotive cooperative effects linked to redox transitions of the metal centers. The crystal structure of oxidized and reduced bovine-heart cytochrome c oxidase reveals, upon reduction, the occurrence of long-range conformational changes in subunit I of the oxidase. Analysis of the crystal structure of cytochrome c oxidase shows the existence of hydrogen-bonded networks of amino acid residues which could undergo redox-linked pK shifts resulting in transmembrane proton translocation. Our group has identified four proteolytic groups undergoing reversible redox-linked pK shifts. Two groups result in being linked to redox transitions of heme a3. One group is apparently linked to CuB. The fourth group is linked to oxido-reduction of heme a. We have shown that the proton transfer resulting from the redox Bohr effects linked to heme a and CuB in the bovine oxidase displays membrane vectorial asymmetry, i.e., protons are taken up from the inner aqueous space (N), upon reduction, and released in the external space (P), upon oxidation of the metals. This direction of proton uptake and release is just what is expected from the vectorial Bohr mechanism. The group linked to heme a, which can transfer up to 0.9 H+/e- at pHs around neutrality, can provide the major contribution to the proton pump. It is proposed that translocation of pumped protons, linked to electron flow through heme a, utilizes a channel (channel D) which extends from a conserved aspartate at the N entrance to a conserved glutamate located between heme a and the binuclear center. The carboxylic group of this glutamic acid, after having delivered, upon electron flow through heme a, pumped protons towards the P phase, once reprotonated from the N phase, moves to deliver, subsequently, to the binuclear center chemical protons consumed in the conversion of the peroxy to ferryl and of the latter to the oxy intermediate in the redox cycle. Site-directed mutagenesis of protolytic residues in subunit I of the aa3-600 quinol oxidase of Bacillus subtilis to non-polar residues revealed that the conserved Lys 304 is critical for the proton pumping activity of the oxidase. Crystal structures of cytochrome c oxidase show that this lysine is at the N entrance of a channel which translocates the protons consumed for the production of the peroxy intermediate. Inhibition of this pathway, by replacement of the lysine, short-circuits protons from channel D to the binuclear center, where they are utilized in the chemistry of oxygen reduction.
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Affiliation(s)
- S Papa
- Institute of Medical Biochemistry and Chemistry, University of Bari, Italy
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14
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Papa S, Capitanio N. Redox Bohr effects (cooperative coupling) and the role of heme a in the proton pump of cytochrome c oxidase. J Bioenerg Biomembr 1998; 30:109-19. [PMID: 9623812 DOI: 10.1023/a:1020519914011] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- S Papa
- Institute of Medical Biochemistry and Chemistry, University of Bari, Italy
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15
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Capitanio N, Capitanio G, De Nitto E, Papa S. Vectorial nature of redox Bohr effects in bovine heart cytochrome c oxidase. FEBS Lett 1997; 414:414-8. [PMID: 9315731 DOI: 10.1016/s0014-5793(97)01043-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The vectorial nature of redox Bohr effects (redox-linked pK shifts) in cytochrome c oxidase from bovine heart incorporated in liposomes has been analyzed. The Bohr effects linked to oxido-reduction of heme a and CuB display membrane vectorial asymmetry. This provides evidence for involvement of redox Bohr effects in the proton pump of the oxidase.
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Affiliation(s)
- N Capitanio
- Institute of Medical Biochemistry and Chemistry, University of Bari, Italy
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16
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Capitanio N, Vygodina TV, Capitanio G, Konstantinov AA, Nicholls P, Papa S. Redox-linked protolytic reactions in soluble cytochrome-c oxidase from beef-heart mitochondria: redox Bohr effects. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1318:255-65. [PMID: 9030268 DOI: 10.1016/s0005-2728(96)00143-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A study is presented of co-operative redox-linked protolytic reactions (redox Bohr effects) in soluble cytochrome-c oxidase purified from bovine-heart mitochondria. Bohr effects were analyzed by direct measurement, with accurate spectrophotometric and potentiometric methods, of H+ uptake and release by the oxidase associated with reduction and oxidation of hemes a and a3. CuA and CuB in the unliganded and in the CN- or CO-liganded enzyme. The results show that there are in the bovine oxidase four protolytic groups undergoing reversible pK shifts upon oxido-reduction of the electron transfer metals. Two groups with pKox and pKred values around 7 and > 12 respectively appear to be linked to redox transitions of heme a3. One group with pKox and pKred around 6 and 7 is apparently linked to CuB, a fourth one with pKox and pKred of 6 and 9 appears to be linked to heme a. The possible nature of the amino acids involved in the redox Bohr effects and their role in H+ translocation is discussed.
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Affiliation(s)
- N Capitanio
- Institute of Medical Biochemistry and Chemistry, University of Bari, Italy
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17
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Altamura N, Capitanio N, Bonnefoy N, Papa S, Dujardin G. The Saccharomyces cerevisiae OXA1 gene is required for the correct assembly of cytochrome c oxidase and oligomycin-sensitive ATP synthase. FEBS Lett 1996; 382:111-5. [PMID: 8612730 DOI: 10.1016/0014-5793(96)00165-2] [Citation(s) in RCA: 121] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The nuclear gene OXA1 was first isolated in Saccharomyces cerevisiae and found to be required at a post-translational step in cytochrome c oxidase biogenesis, probably at the level of assembly. Mutations in OXA1 lead to a complete respiratory deficiency. The protein Oxa1p is conserved through evolution and a human homolog has been isolated by functional complementation of a yeast oxa1- mutant. In order to further our understanding of the role of Oxa1p, we have constructed two yeast strains in which the OXA1 open reading frame was almost totally deleted. Cytochrome spectra and enzymatic activity measurements show the absence of heme aa3 and of a cytochrome c oxido-reductase activity and dramatic decrease of the oligomycin sensitive ATPase activity. Analysis of the respiratory complexes in non-denaturing gels reveals that Oxa1p is necessary for the correct assembly of the cytochrome c oxidase and the ATP synthase complex.
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Affiliation(s)
- N Altamura
- Centro di Studio sui Mitocondri e Metabolismo Energetico, CNR, Bari, Italy
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18
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Papa S, Lorusso M, Capitanio N. Mechanistic and phenomenological features of proton pumps in the respiratory chain of mitochondria. J Bioenerg Biomembr 1994; 26:609-18. [PMID: 7721722 DOI: 10.1007/bf00831535] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023]
Abstract
Various direct, indirect (kinetic and thermodynamic), and combined mechanisms have been proposed to explain the conversion of redox energy into a transmembrane protonmotive force (delta p) by enzymatic complexes of respiratory chains. The conceptual evolution of these models is examined. The characteristics of thermodynamic coupling between redox transitions of electron carriers and scalar proton transfer in cytochrome c oxidase and its possible involvement in proton pumping is discussed. Other aspects dealt with in this paper are: (i) variability of <--H+/e- stoichiometries, in cytochrome c oxidase and cytochrome c reductase and its mechanistic implications; (ii) possible models by which the reduction of dioxygen to water at the binuclear heme-copper center of protonmotive oxidases can be directly involved in proton pumping. Finally a unifying concept for proton pumping by the redox complexes of respiratory chain is presented.
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Affiliation(s)
- S Papa
- Institute of Medical Biochemistry and Chemistry, University of Bari, Italy
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Capitanio N, De Nitto E, Villani G, Capitanio G, Papa S. Protonmotive activity of cytochrome c oxidase: control of oxidoreduction of the heme centers by the protonmotive force in the reconstituted beef heart enzyme. Biochemistry 1990; 29:2939-45. [PMID: 2159780 DOI: 10.1021/bi00464a008] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
This paper contributes to the characterization of partial steps of electron and proton transfer in mitochondrial cytochrome c oxidase with respect to their membrane arrangement and involvement in energy-linked protonmotive activity. It is shown that delta psi controls electron flow from cytochrome c to heme a is consistent with the view that the latter center is buried in the membrane in a central position. The pressure exerted by delta psi on oxidation of heme alpha 3 by O2 indicates also that this center is buried in the membrane at some distance from the inner side and is consistent with observations showing that protons consumed in the reduction of O2 to H2O derive from the inner space. Electron flow from heme alpha to heme alpha 3 is shown to be specifically controlled by delta pH and in particular by the pH of the inner phase. Analysis of the effect of DCCD treatment of oxidase vesicles reveals that concentrations of this reagent which result in selective modification of subunit III (Prochaska et al., 1981) produce inhibition of redox-linked proton release. Higher concentrations of DCCD which result also in modification of subunits II and IV (Prochaska et al., 1981) cause inhibition of the pH-dependent electron-transfer step from heme alpha to heme alpha 3.
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Affiliation(s)
- N Capitanio
- Institute of Medical Biochemistry and Chemistry, University of Bari, Italy
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Papa S, Capitanio N, Steverding D. Characteristics of the protonmotive activity of mammalian cytochrome c oxidase and their modification by amino acid reagents. Ann N Y Acad Sci 1988; 550:238-53. [PMID: 2854396 DOI: 10.1111/j.1749-6632.1988.tb35339.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Experimental analysis of the protonmotive activity of reconstituted cytochrome c oxidase from beef heart reveals the following features: (1) The observed H+:e- ratio for redox-linked proton ejection from oxidase vesicles is variable, being affected by various effectors that also influence the catalytic process. (2) Proton ejection appears to be associated with electron transfer from heme a (+CuA) to heme a3 (+CuB). (3) Chemical modification studies contribute to indentification of proton-conduction pathways in the protein and/or residues involved in the coupling process between redox and protonmotive activity. In intact rat liver mitochondria, under physiological conditions of dehydrogenase activity and delta microH+ generation by the respiratory chain cytochrome oxidase, does not appear to contribute significant H+ pumping. The relevance of what is observed is discussed in terms of possible mechanisms and physiological role.
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Affiliation(s)
- S Papa
- Institute of Medical Biochemistry and Chemistry, University of Bari, Italy
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