51
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Zickermann V, Angerer H, Ding MG, Nübel E, Brandt U. Small single transmembrane domain (STMD) proteins organize the hydrophobic subunits of large membrane protein complexes. FEBS Lett 2010; 584:2516-25. [PMID: 20398659 DOI: 10.1016/j.febslet.2010.04.021] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 03/30/2010] [Accepted: 04/09/2010] [Indexed: 11/24/2022]
Abstract
The large membrane protein complexes of mitochondrial oxidative phosphorylation are composed of central subunits that are essential for their bioenergetic core function and accessory subunits that may assist in regulation, assembly or stabilization. Although sequence conservation is low, a significant proportion of the accessory subunits is characterized by a common single transmembrane (STMD) topology. The STMD signature is also found in subunits of other membrane protein complexes. We hypothesize that the general function of STMD subunits is to organize the hydrophobic subunits of large membrane protein complexes in specialized environments like the inner mitochondrial membrane.
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Affiliation(s)
- Volker Zickermann
- Goethe-Universität, Fachbereich Medizin, Molekulare Bioenergetik, Cluster of Excellence Frankfurt "Macromolecular Complexes", Frankfurt am Main, Germany
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52
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Frick NT, Bystriansky JS, Ip YK, Chew SF, Ballantyne JS. Cytochrome c oxidase is regulated by modulations in protein expression and mitochondrial membrane phospholipid composition in estivating African lungfish. Am J Physiol Regul Integr Comp Physiol 2010; 298:R608-16. [DOI: 10.1152/ajpregu.90815.2008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We examined some of the potential mechanisms lungfish ( Protopterus dolloi ) use to regulate cytochrome c oxidase (CCO), during metabolic depression. CCO activity was reduced by 67% in isolated liver mitochondria of estivating fish. This was likely accomplished, in part, by the 46% reduction in CCO subunit I protein expression in the liver. No change in the mRNA expression levels of CCO subunits I, II, III, and IV were found in the liver, suggesting CCO is under translational regulation; however, in the kidney, messenger limitation may be a factor as the expression of subunits I and II were depressed (∼10-fold) during estivation, suggesting tissue-specific mechanisms of regulation. CCO is influenced by mitochondrial membrane phospholipids, particularly cardiolipin (CL). In P. dolloi , the phospholipid composition of the liver mitochondrial membrane changed during estivation, with a ∼2.3-fold reduction in the amount of CL. Significant positive correlations were found between CCO activity and the amount of CL and phosphatidylethanolamine within the mitochondrial membrane. It appears CCO activity is regulated through multiple mechanisms in P. dolloi , and individual subunits of CCO are regulated independently, and in a tissue-specific manner. It is proposed that altering the amount of CL within the mitochondrial membrane may be a means of regulating CCO activity during metabolical depression in the African lungfish, P. dolloi .
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Affiliation(s)
- N. T. Frick
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
| | - J. S. Bystriansky
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
| | - Y. K. Ip
- Department of Biological Sciences, National University of Singapore, Singapore, Republic of Singapore; and
| | - S. F. Chew
- Natural Sciences, National Institute of Education, Nanyang Technological University, Singapore, Republic of Singapore
| | - J. S. Ballantyne
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
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53
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Acsadi G, Lee I, Li X, Khaidakov M, Pecinova A, Parker GC, Hüttemann M. Mitochondrial dysfunction in a neural cell model of spinal muscular atrophy. J Neurosci Res 2010; 87:2748-56. [PMID: 19437551 DOI: 10.1002/jnr.22106] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Mutations of the survival motor neuron (SMN) gene in spinal muscular atrophy (SMA) lead to anterior horn cell death. The cause is unknown, but motor neurons depend substantially on mitochondrial oxidative phosphorylation (OxPhos) for normal function. Therefore, mitochondrial parameters were analyzed in an SMA cell culture model using small interfering RNA (siRNA) transfection that decreased Smn expression in NSC-34 cells to disease levels. Smn siRNA knock-down resulted in 35% and 66% reduced Smn protein levels 48 and 72 hr posttransfection, respectively. ATP levels were reduced by 14% and 26% at 48 and 72 hr posttransfection, respectively, suggesting decreased ATP production or increased energy demand in neural cells. Smn knock-down resulted in increased mitochondrial membrane potential and increased free radical production. Changes in activity of cytochrome c oxidase (CcO), a key OxPhos component, were observed at 72 hr with a 26% increase in oxygen consumption. This suggests a compensatory activation of the aerobic pathway, resulting in increased mitochondrial membrane potentials, a condition known to lead to the observed increase in free radical production. Further testing suggested that changes in ATP at 24 hr precede observable indices of cell injury at 48 hr. We propose that energy paucity and increased mitochondrial free radical production lead to accumulated cell damage and eventual cell death in Smn-depleted neural cells. Mitochondrial dysfunction may therefore be important in SMA pathology and may represent a new therapeutic target.
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Affiliation(s)
- Gyula Acsadi
- Children's Hospital of Michigan, Carman and Ann Adams Department of Pediatrics, Detroit, Michigan, USA
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54
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Abstract
PMD (Pelizaeus–Merzbacher disease), a CNS (central nervous system) disease characterized by shortened lifespan and severe neural dysfunction, is caused by mutations of the PLP1 (X-linked myelin proteolipid protein) gene. The majority of human PLP1 mutations are caused by duplications; almost all others are caused by missense mutations. The cellular events leading to the phenotype are unknown. The same mutations in non-humans make them ideal models to study the mechanisms that cause neurological sequelae. In the present study we show that mice with Plp1 duplications (Plp1tg) have major mitochondrial deficits with a 50% reduction in ATP, a drastically reduced mitochondrial membrane potential and increased numbers of mitochondria. In contrast, the jp (jimpy) mouse with a Plp1 missense mutation exhibits normal mitochondrial function. We show that PLP in the Plp1tg mice and in Plp1-transfected cells is targeted to mitochondria. PLP has motifs permissive for insertion into mitochondria and deletions near its N-terminus prevent its co-localization to mitochondria. These novel data show that Plp1 missense mutations and duplications of the native Plp1 gene initiate uniquely different cellular responses.
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55
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Kadenbach B, Ramzan R, Wen L, Vogt S. New extension of the Mitchell Theory for oxidative phosphorylation in mitochondria of living organisms. Biochim Biophys Acta Gen Subj 2009; 1800:205-12. [PMID: 19409964 DOI: 10.1016/j.bbagen.2009.04.019] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2009] [Revised: 04/22/2009] [Accepted: 04/27/2009] [Indexed: 01/04/2023]
Abstract
The Mitchell Theory implies the proton motive force Deltap across the inner mitochondrial membrane as the energy-rich intermediate of oxidative phosphorylation. Deltap is composed mainly of an electrical (DeltaPsi(m)) and a chemical part (DeltapH) and generated by the respiratory chain complexes I, III and IV. It is consumed mostly by the ATP synthase (complex V) to produce ATP. The free energy of electron transport within the proton pumps is sufficient to generate Deltap of about 240 mV. The proton permeability of biological membranes, however, increases exponentially above 130 mV leading to a waste of energy at high values (DeltaPsi(m)>140 mV). In addition, at DeltaPsi(m)>140 mV, the production of the superoxide radical anion O(2)(-) at complexes I, II and III increases exponentially with increasing DeltaPsi(m). O(2)(-) and its neutral product H(2)O(2) (=ROS, reactive oxygen species) induce oxidative stress which participates in aging and in the generation of degenerative diseases. Here we describe a new mechanism which acts independently of the Mitchell Theory and keeps DeltaPsi(m) at low values through feedback inhibition of complex IV (cytochrome c oxidase) at high ATP/ADP ratios, thus preventing the formation of ROS and maintaining high efficiency of oxidative phosphorylation.
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Affiliation(s)
- Bernhard Kadenbach
- Fachbereich Chemie, Cardiovascular Laboratory, Philipps-University, D-35032 Marburg, Germany
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56
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Suthammarak W, Yang YY, Morgan PG, Sedensky MM. Complex I function is defective in complex IV-deficient Caenorhabditis elegans. J Biol Chem 2008; 284:6425-35. [PMID: 19074434 DOI: 10.1074/jbc.m805733200] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Cytochrome c oxidase (COX) is hypothesized to be an important regulator of oxidative phosphorylation. However, no animal phenotypes have been described due to genetic defects in nuclear-encoded subunits of COX. We knocked down predicted homologues of COX IV and COX Va in the nematode Caenorhabditis elegans. Animals treated with W09C5.8 (COX IV) or Y37D8A.14 (COX Va) RNA interference had shortened lifespans and severe defects in mitochondrial respiratory chain function. Amount and activity of complex IV, as well as supercomplexes that included complex IV, were decreased in COX-deficient worms. The formation of supercomplex I:III was not dependent on COX. We found that COX deficiencies decreased intrinsic complex I enzymatic activity, as well as complex I-III enzymatic activity. However, overall amounts of complex I were not decreased in these animals. Surprisingly, intrinsic complex I enzymatic activity is dependent on the presence of complex IV, despite no overall decrease in the amount of complex I. Presumably the association of complex I with complex IV within the supercomplex I:III:IV enhances electron flow through complex I. Our results indicate that reduction of a single subunit within the electron transport chain can affect multiple enzymatic steps of electron transfer, including movement within a different protein complex. Patients presenting with multiple defects of electron transport may, in fact, harbor a single genetic defect.
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Affiliation(s)
- Wichit Suthammarak
- Department of Genetics, Case Western Reserve University, and Department of Anesthesiology, University Hospital, Cleveland, OH, USA
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57
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Hüttemann M, Lee I, Pecinova A, Pecina P, Przyklenk K, Doan JW. Regulation of oxidative phosphorylation, the mitochondrial membrane potential, and their role in human disease. J Bioenerg Biomembr 2008; 40:445-56. [PMID: 18843528 DOI: 10.1007/s10863-008-9169-3] [Citation(s) in RCA: 179] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Accepted: 07/01/2008] [Indexed: 01/09/2023]
Abstract
Thirty years after Peter Mitchell was awarded the Nobel Prize for the chemiosmotic hypothesis, which links the mitochondrial membrane potential generated by the proton pumps of the electron transport chain to ATP production by ATP synthase, the molecular players involved once again attract attention. This is so because medical research increasingly recognizes mitochondrial dysfunction as a major factor in the pathology of numerous human diseases, including diabetes, cancer, neurodegenerative diseases, and ischemia reperfusion injury. We propose a model linking mitochondrial oxidative phosphorylation (OxPhos) to human disease, through a lack of energy, excessive free radical production, or a combination of both. We discuss the regulation of OxPhos by cell signaling pathways as a main regulatory mechanism in higher organisms, which in turn determines the magnitude of the mitochondrial membrane potential: if too low, ATP production cannot meet demand, and if too high, free radicals are produced. This model is presented in light of the recently emerging understanding of mechanisms that regulate mammalian cytochrome c oxidase and its substrate cytochrome c as representative enzymes for the entire OxPhos system.
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Affiliation(s)
- Maik Hüttemann
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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58
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Samavati L, Lee I, Mathes I, Lottspeich F, Hüttemann M. Tumor necrosis factor alpha inhibits oxidative phosphorylation through tyrosine phosphorylation at subunit I of cytochrome c oxidase. J Biol Chem 2008; 283:21134-44. [PMID: 18534980 PMCID: PMC3258931 DOI: 10.1074/jbc.m801954200] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2008] [Revised: 05/06/2008] [Indexed: 11/06/2022] Open
Abstract
Mitochondrial oxidative phosphorylation provides most cellular energy. As part of this process, cytochrome c oxidase (CcO) pumps protons across the inner mitochondrial membrane, contributing to the generation of the mitochondrial membrane potential, which is used by ATP synthase to produce ATP. During acute inflammation, as in sepsis, aerobic metabolism appears to malfunction and switches to glycolytic energy production. The pro-inflammatory cytokine tumor necrosis factor alpha (TNFalpha) has been shown to play a central role in inflammation. We hypothesized that TNFalpha-triggered cell signaling targets CcO, which is a central enzyme of the aerobic energy metabolism and can be regulated through phosphorylation. Using total bovine and murine hepatocyte homogenates TNFalpha treatment led to an approximately 60% reduction in CcO activity. In contrast, there was no direct effect of TNFalpha on CcO activity using isolated mitochondria and purified CcO, indicating that a TNFalpha-triggered intracellular signaling cascade mediates CcO inhibition. CcO isolated after TNFalpha treatment showed tyrosine phosphorylation on CcO catalytic subunit I and was approximately 50 and 70% inhibited at high cytochrome c concentrations in the presence of allosteric activator ADP and inhibitor ATP, respectively. CcO phosphorylation occurs on tyrosine 304 as demonstrated with a phosphoepitope-specific antibody. Furthermore, the mitochondrial membrane potential was decreased in H2.35 cells in response to TNFalpha. Concomitantly, cellular ATP was more than 35 and 64% reduced in murine hepatocytes and H2.35 cells. We postulate that an important contributor in TNFalpha-mediated pathologies, such as sepsis, is energy paucity, which parallels the poor tissue oxygen extraction and utilization found in such patients.
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Affiliation(s)
- Lobelia Samavati
- Department of Medicine,
Division of Pulmonary/Critical Care and Sleep Medicine, Wayne State University
School of Medicine, Detroit, Michigan 48201, the
Center for Molecular Medicine and
Genetics, Wayne State University School of Medicine, Detroit, Michigan 48201,
and the Max Planck Institute of
Biochemistry, D-82152 Martinsried, Germany
| | - Icksoo Lee
- Department of Medicine,
Division of Pulmonary/Critical Care and Sleep Medicine, Wayne State University
School of Medicine, Detroit, Michigan 48201, the
Center for Molecular Medicine and
Genetics, Wayne State University School of Medicine, Detroit, Michigan 48201,
and the Max Planck Institute of
Biochemistry, D-82152 Martinsried, Germany
| | - Isabella Mathes
- Department of Medicine,
Division of Pulmonary/Critical Care and Sleep Medicine, Wayne State University
School of Medicine, Detroit, Michigan 48201, the
Center for Molecular Medicine and
Genetics, Wayne State University School of Medicine, Detroit, Michigan 48201,
and the Max Planck Institute of
Biochemistry, D-82152 Martinsried, Germany
| | - Friedrich Lottspeich
- Department of Medicine,
Division of Pulmonary/Critical Care and Sleep Medicine, Wayne State University
School of Medicine, Detroit, Michigan 48201, the
Center for Molecular Medicine and
Genetics, Wayne State University School of Medicine, Detroit, Michigan 48201,
and the Max Planck Institute of
Biochemistry, D-82152 Martinsried, Germany
| | - Maik Hüttemann
- Department of Medicine,
Division of Pulmonary/Critical Care and Sleep Medicine, Wayne State University
School of Medicine, Detroit, Michigan 48201, the
Center for Molecular Medicine and
Genetics, Wayne State University School of Medicine, Detroit, Michigan 48201,
and the Max Planck Institute of
Biochemistry, D-82152 Martinsried, Germany
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59
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Helling S, Vogt S, Rhiel A, Ramzan R, Wen L, Marcus K, Kadenbach B. Phosphorylation and kinetics of mammalian cytochrome c oxidase. Mol Cell Proteomics 2008; 7:1714-24. [PMID: 18541608 DOI: 10.1074/mcp.m800137-mcp200] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The influence of protein phosphorylation on the kinetics of cytochrome c oxidase was investigated by applying Western blotting, mass spectrometry, and kinetic measurements with an oxygen electrode. The isolated enzyme from bovine heart exhibited serine, threonine, and/or tyrosine phosphorylation in various subunits, except subunit I, by using phosphoamino acid-specific antibodies. The kinetics revealed slight inhibition of oxygen uptake in the presence of ATP, as compared with the presence of ADP. Mass spectrometry identified the phosphorylation of Ser-34 at subunit IV and Ser-4 and Thr-35 at subunit Va. Incubation of the isolated enzyme with protein kinase A, cAMP, and ATP resulted in serine and threonine phosphorylation of subunit I, which was correlated with sigmoidal inhibition kinetics in the presence of ATP. This allosteric ATP-inhibition of cytochrome c oxidase was also found in rat heart mitochondria, which had been rapidly prepared in the presence of protein phosphatase inhibitors. The isolated rat heart enzyme, prepared from the mitochondria by blue native gel electrophoresis, showed serine, threonine, and tyrosine phosphorylation of subunit I. It is concluded that the allosteric ATP-inhibition of cytochrome c oxidase, previously suggested to keep the mitochondrial membrane potential and thus the reactive oxygen species production in cells at low levels, occurs in living cells and is based on phosphorylation of cytochrome c oxidase subunit I.
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Affiliation(s)
- Stefan Helling
- Medizinisches Proteom-Center, Funktionelle Proteomik, Ruhr-Universität Bochum, Germany
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60
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Dhar SS, Ongwijitwat S, Wong-Riley MTT. Nuclear respiratory factor 1 regulates all ten nuclear-encoded subunits of cytochrome c oxidase in neurons. J Biol Chem 2007; 283:3120-3129. [PMID: 18077450 DOI: 10.1074/jbc.m707587200] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Cytochrome c oxidase (COX) is one of only four bigenomic proteins in mammalian cells, having ten subunits encoded in the nuclear genome and three in the mitochondrial DNA. The mechanism of its bigenomic control is not well understood. The ten nuclear subunits are on different chromosomes, and the possibility of their coordinate regulation by the same transcription factor(s) deserves serious consideration. The present study tested our hypothesis that nuclear respiratory factor 1 (NRF-1) serves such a role in subunit coordination. Following in silico analysis of murine nuclear-encoded COX subunit promoters, electrophoretic mobility shift and supershift assays indicated NRF-1 binding to all ten promoters. In vivo chromatin immunoprecipitation assays also showed NRF-1 binding to all ten promoters in murine neuroblastoma cells. Site-directed mutagenesis of putative NRF-1 binding sites confirmed the functionality of NRF-1 binding on all ten COX promoters. These sites are highly conserved among mice, rats, and humans. Silencing of NRF-1 with RNA interference reduced all ten COX subunit mRNAs and mRNAs of other genes involved in mitochondrial biogenesis. We conclude that NRF-1 plays a significant role in coordinating the transcriptional regulation of all ten nuclear-encoded COX subunits in neurons. Moreover, NRF-1 is known to activate mitochondrial transcription factors A and B, thereby indirectly regulating the expressions of the three mitochondrial-encoded COX subunits. Thus, NRF-1 and our previously described NRF-2 prove to be the two key bigenomic coordinators for transcriptional regulation of all cytochrome c oxidase subunits in neurons. Possible interactions between the NRFs will be investigated in the future.
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Affiliation(s)
- Shilpa S Dhar
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Sakkapol Ongwijitwat
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Margaret T T Wong-Riley
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
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61
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Regulation of mitochondrial oxidative phosphorylation through cell signaling. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1773:1701-20. [DOI: 10.1016/j.bbamcr.2007.10.001] [Citation(s) in RCA: 191] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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62
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Hüttemann M, Lee I, Kreipke CW, Petrov T. Suppression of the inducible form of nitric oxide synthase prior to traumatic brain injury improves cytochrome c oxidase activity and normalizes cellular energy levels. Neuroscience 2007; 151:148-54. [PMID: 18037245 DOI: 10.1016/j.neuroscience.2007.09.029] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2007] [Revised: 09/11/2007] [Accepted: 10/11/2007] [Indexed: 01/09/2023]
Abstract
We have previously shown that the observed immediate increase in nitric oxide (NO) plays a significant role in the control of the cerebral microcirculation following traumatic brain injury (TBI). However, a second consequence of increased NO production after TBI may be impaired mitochondrial function, due to the fact that NO is a well-known inhibitor of cytochrome c oxidase (CcO). CcO is a key enzyme of the mitochondrial oxidative phosphorylation (OxPhos) machinery, which creates cellular energy in the form of ATP. NO competes with oxygen at the heme a(3)-Cu(B) reaction center of CcO. We thus hypothesized that TBI triggers inhibition of CcO, which would in turn lead to a decreased energy production by OxPhos at a time of an elevated energy demand for tissue remodeling. Here we show that TBI as induced by an acceleration weight drop model of diffuse brain injury in rats leads to CcO inhibition and dramatically decreased ATP levels in brain cortex. CcO inhibition can be partially restored by application of iNOS antisense oligonucleotides prior to TBI, which leads to a normalization of ATP levels similar to the controls. We propose that a lack of energy after TBI caused by inhibition of CcO is an important aspect of trauma pathology.
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Affiliation(s)
- M Hüttemann
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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63
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Horvat S, Beyer C, Arnold S. Effect of hypoxia on the transcription pattern of subunit isoforms and the kinetics of cytochrome c oxidase in cortical astrocytes and cerebellar neurons. J Neurochem 2006; 99:937-51. [PMID: 16981895 DOI: 10.1111/j.1471-4159.2006.04134.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Brain energy metabolism essentially depends on the availability of oxygen representing the energetic substrate for cytochrome c oxidase (COX). The catalytic activity of mammalian COX is regulated by binding of ATP to the N-terminus of subunit IV. This causes an allosteric inhibition of the enzyme at a high energy level and thus plays an important role in adjusting energy production to cellular energy requirements. We have studied COX activity in cortical astrocytes and cerebellar granule cells after normoxia and hypoxia treatment. Differences in the kinetic behaviour of COX from these two brain cell types can be addressed to a differential, but cell type-specific, expression of the COX subunit IV-2 isoform. Besides COX isoform IV-1, which is ubiquitously transcribed in all mammalian tissues, we also detected low levels of COX isoform IV-2 in cerebellar neurons, but not in cortical astrocytes. Under conditions of oxygen deprivation, transcription of COX IV-2 is induced in astrocytes and further up-regulated in cerebellar granule cells. Elevated transcription levels of the COX IV-2 isoform are accompanied by an abolition of the allosteric inhibition of COX by ATP. We conclude that the presence of the COX isoform IV-2 suppresses the sensitivity of COX to its allosteric regulator ATP and overrules the regulation of COX by the cellular energy level. This suggests a pivotal role of COX as an oxygen sensor for brain function.
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Affiliation(s)
- Susann Horvat
- Institute for Neuroanatomy, Faculty of Medicine RWTH Aachen, Aachen, Germany
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64
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Lee I, Salomon AR, Ficarro S, Mathes I, Lottspeich F, Grossman LI, Hüttemann M. cAMP-dependent tyrosine phosphorylation of subunit I inhibits cytochrome c oxidase activity. J Biol Chem 2004; 280:6094-100. [PMID: 15557277 DOI: 10.1074/jbc.m411335200] [Citation(s) in RCA: 166] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Signaling pathways targeting mitochondria are poorly understood. We here examine phosphorylation by the cAMP-dependent pathway of subunits of cytochrome c oxidase (COX), the terminal enzyme of the electron transport chain. Using anti-phospho antibodies, we show that cow liver COX subunit I is tyrosinephosphorylated in the presence of theophylline, a phosphodiesterase inhibitor that creates high cAMP levels, but not in its absence. The site of phosphorylation, identified by mass spectrometry, is tyrosine 304 of COX catalytic subunit I. Subunit I phosphorylation leads to a decrease of V(max) and an increase of K(m) for cytochrome c and shifts the reaction kinetics from hyperbolic to sigmoidal such that COX is fully or strongly inhibited up to 10 mum cytochrome c substrate concentrations, even in the presence of allosteric activator ADP. To assess our findings with the isolated enzyme in a physiological context, we tested the starvation signal glucagon on human HepG2 cells and cow liver tissue. Glucagon leads to COX inactivation, an effect also observed after incubation with adenylyl cyclase activator forskolin. Thus, the glucagon receptor/G-protein/cAMP pathway regulates COX activity. At therapeutic concentrations used for asthma relief, theophylline causes lung COX inhibition and decreases cellular ATP levels, suggesting a mechanism for its clinical action.
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Affiliation(s)
- Icksoo Lee
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, 540 E. Canfield Ave., Detroit, MI 48201, USA
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65
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Ongwijitwat S, Wong-Riley MTT. Functional analysis of the rat cytochrome c oxidase subunit 6A1 promoter in primary neurons. Gene 2004; 337:163-71. [PMID: 15276212 DOI: 10.1016/j.gene.2004.04.024] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2004] [Revised: 04/04/2004] [Accepted: 04/26/2004] [Indexed: 11/16/2022]
Abstract
Cytochrome c oxidase (COX) is a multimeric enzyme consisting of 13 subunits that are encoded in both mitochondrial and nuclear genomes. We analyzed the promoter of the rat gene encoding the liver isoform of COX subunit VIa. Using transiently transfected primary neuronal cultures as a model system, we found that the basal promoter activity of this gene is localized to a region between positions -244 and +58 relative to the transcriptional start site. This region contains putative binding sites for the transcription factors Sp1, NRF-1, and NRF-2. Two of the NRF-2 sites in this basal promoter are organized in a tandem repeat. A deletion that disrupted this tandem repeat reduced transcription to approximately 25% of the basal level. Additional small deletion series and point mutation experiments confirmed the presence of two functional NRF-2 sites arranged in a tandem repeat, as well as a NRF-1 site and an Sp1 site. In vivo binding of NRF-2 to the rCOX6A1 promoter was confirmed with chromatin immunoprecipitation assay (ChIP). We conclude that Sp1, NRF-1, and NRF-2 are important in activating transcription of the rat COX6A1 gene.
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Affiliation(s)
- Sakkapol Ongwijitwat
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
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66
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Richter OMH, Ludwig B. Cytochrome c oxidase--structure, function, and physiology of a redox-driven molecular machine. Rev Physiol Biochem Pharmacol 2003; 147:47-74. [PMID: 12783267 DOI: 10.1007/s10254-003-0006-0] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Cytochome c oxidase is the terminal member of the electron transport chains of mitochondria and many bacteria. Providing an efficient mechanism for dioxygen reduction on the one hand, it also acts as a redox-linked proton pump, coupling the free energy of water formation to the generation of a transmembrane electrochemical gradient to eventually drive ATP synthesis. The overall complexity of the mitochondrial enzyme is also reflected by its subunit structure and assembly pathway, whereas the diversity of the bacterial enzymes has fostered the notion of a large family of heme-copper terminal oxidases. Moreover, the successful elucidation of 3-D structures for both the mitochondrial and several bacterial oxidases has greatly helped in designing mutagenesis approaches to study functional aspects in these enzymes.
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Affiliation(s)
- O-M H Richter
- Institute of Biochemistry, Biocenter, J.W. Goethe-Universität, Marie-Curie-Str. 9, 60439 Frankfurt, Germany.
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67
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Hüttemann M, Schmidt TR, Grossman LI. A third isoform of cytochrome c oxidase subunit VIII is present in mammals. Gene 2003; 312:95-102. [PMID: 12909344 DOI: 10.1016/s0378-1119(03)00604-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The terminal enzyme of the mitochondrial respiratory chain, cytochrome c oxidase (COX), contains three mitochondrial and ten nuclear encoded subunits in mammals. Three of the nuclear subunits (VIa, VIIa, and VIII) have muscle and non-muscle-specific isoforms, subunit IV contains a lung-specific isoform, and subunit VIb contains a testes-specific isoform. For subunit VIII, the smallest nuclear encoded COX polypeptide, we have now found a third gene (COX 8-3), which has been identified in human, lemur, rat, and mouse, suggesting that it is present in a broad range of Eutherian mammals. Sequence similarity and gene structure support the homology of COX8-3 to the other subunit VIII isoforms, indicating that all three are the product of gene duplications. COX VIII-3 protein is mitochondrially-targeted, as shown by a fluorescent COX VIII3/DsRed fusion protein. Both the mitochondrial targeting and its sequence conservation suggest that COXVIII-3 functions as part of the COX holoenzyme and could have a tissue-specific role, as is the case for the other two isoforms. Questions remain about where COX8-3 is predominantly expressed. However, detection of full-length cDNAs, lower levels of sequence divergence at the first and second codon positions compared to the third, and a conserved gene structure indicate that COX VIII-3 is an expressed gene whose origin dates to at least 91 million years ago.
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Affiliation(s)
- Maik Hüttemann
- Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA
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68
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Kadenbach B. Intrinsic and extrinsic uncoupling of oxidative phosphorylation. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1604:77-94. [PMID: 12765765 DOI: 10.1016/s0005-2728(03)00027-6] [Citation(s) in RCA: 362] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
This article reviews parameters of extrinsic uncoupling of oxidative phosphorylation (OxPhos) in mitochondria, based on induction of a proton leak across the inner membrane. The effects of classical uncouplers, fatty acids, uncoupling proteins (UCP1-UCP5) and thyroid hormones on the efficiency of OxPhos are described. Furthermore, the present knowledge on intrinsic uncoupling of cytochrome c oxidase (decrease of H(+)/e(-) stoichiometry=slip) is reviewed. Among the three proton pumps of the respiratory chain of mitochondria and bacteria, only cytochrome c oxidase is known to exhibit a slip of proton pumping. Intrinsic uncoupling was shown after chemical modification, by site-directed mutagenesis of the bacterial enzyme, at high membrane potential DeltaPsi, and in a tissue-specific manner to increase thermogenesis in heart and skeletal muscle by high ATP/ADP ratios, and in non-skeletal muscle tissues by palmitate. In addition, two mechanisms of respiratory control are described. The first occurs through the membrane potential DeltaPsi and maintains high DeltaPsi values (150-200 mV). The second occurs only in mitochondria, is suggested to keep DeltaPsi at low levels (100-150 mV) through the potential dependence of the ATP synthase and the allosteric ATP inhibition of cytochrome c oxidase at high ATP/ADP ratios, and is reversibly switched on by cAMP-dependent phosphorylation. Finally, the regulation of DeltaPsi and the production of reactive oxygen species (ROS) in mitochondria at high DeltaPsi values (150-200 mV) are discussed.
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Affiliation(s)
- Bernhard Kadenbach
- Fachbereich Chemie, Philipps-Universität, Hans-Meerwein-Strasse, D-35032 Marburg, Germany.
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69
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Lee I, Bender E, Kadenbach B. Control of mitochondrial membrane potential and ROS formation by reversible phosphorylation of cytochrome c oxidase. Mol Cell Biochem 2003. [PMID: 12162461 DOI: 10.1023/a:1015921513720] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Phosphorylation of isolated cytochrome c oxidase from bovine kidney and heart, and of the reconstituted heart enzyme, with protein kinase A, cAMP and ATP turns on the allosteric ATP-inhibition at high ATP/ADP ratios. Also incubation of isolated bovine liver mitochondria only with cAMP andATP turns on, and subsequent incubation with Ca2+ turns off the allosteric ATP-inhibition of cytochrome c oxidase. In the bovine heart enzyme occur only three consensus sequences for cAMP-dependent phosphorylation (in subunits I, III and Vb). The evolutionary conservation of RRYS441 at the cytosolic side of subunit I, together with the above results, suggest that phosphorylation of Ser441 turns on the allosteric ATP-inhibition of cytochrome c oxidase. The results support the 'molecular-physiological hypothesis' [29], which proposes a low mitochondrial membrane potential through the allosteric ATP-inhibition. A hormone- or agonist-stimulated increase of cellular [Ca2+] is suggested to activate a mitochondrial protein phosphatase which dephosphorylates cytochrome c oxidase, turns off the allosteric ATP-inhibition and results in increase of mitochondrial membrane potential and ROS formation.
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Affiliation(s)
- Icksoo Lee
- Fachereich Chemie, Philipps-University, Marburg, Germany
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70
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Lee I, Bender E, Kadenbach B. Control of mitochondrial membrane potential and ROS formation by reversible phosphorylation of cytochrome c oxidase. Mol Cell Biochem 2002. [PMID: 12162461 DOI: 10.1007/978-1-4615-1087-1_7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Phosphorylation of isolated cytochrome c oxidase from bovine kidney and heart, and of the reconstituted heart enzyme, with protein kinase A, cAMP and ATP turns on the allosteric ATP-inhibition at high ATP/ADP ratios. Also incubation of isolated bovine liver mitochondria only with cAMP andATP turns on, and subsequent incubation with Ca2+ turns off the allosteric ATP-inhibition of cytochrome c oxidase. In the bovine heart enzyme occur only three consensus sequences for cAMP-dependent phosphorylation (in subunits I, III and Vb). The evolutionary conservation of RRYS441 at the cytosolic side of subunit I, together with the above results, suggest that phosphorylation of Ser441 turns on the allosteric ATP-inhibition of cytochrome c oxidase. The results support the 'molecular-physiological hypothesis' [29], which proposes a low mitochondrial membrane potential through the allosteric ATP-inhibition. A hormone- or agonist-stimulated increase of cellular [Ca2+] is suggested to activate a mitochondrial protein phosphatase which dephosphorylates cytochrome c oxidase, turns off the allosteric ATP-inhibition and results in increase of mitochondrial membrane potential and ROS formation.
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Affiliation(s)
- Icksoo Lee
- Fachereich Chemie, Philipps-University, Marburg, Germany
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71
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Lee I, Bender E, Arnold S, Kadenbach B. New control of mitochondrial membrane potential and ROS formation--a hypothesis. Biol Chem 2001; 382:1629-36. [PMID: 11843176 DOI: 10.1515/bc.2001.198] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
A new control of mitochondrial membrane potential delta(psi)m and formation of reactive oxygen species (ROS) is presented, based on allosteric ATP-inhibition of cytochrome c oxidase at high intramitochondrial ATP/ADP ratios. Since the rate of ATP synthesis by the ATP synthase is already maximal at low membrane potentials (100-120 mV), the ATP/ADP ratio will also be maximal at this delta(psi)m (at constant rate of ATP consumption). Therefore the control of respiration by the ATP/ADP-ratio keeps delta(psi)m low. In contrast, the known 'respiratory control' leads to an inhibition of respiration only at high delta(psi)m values (150-200 mV) which cause ROS formation. ATP-inhibition of cytochrome c oxidase is switched on and off by reversible phosphorylation (via cAMP and calcium, respectively). We propose that 'stress hormones' which increase intracellular [Ca2+] also increase delta(psi)m and ROS formation, which promote degenerative diseases and accelerate aging.
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Affiliation(s)
- I Lee
- Fachbereich Chemie, Philipps-Universität, Marburg, Germany
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72
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Abstract
Detergents are invaluable tools for studying membrane proteins. However, these deceptively simple, amphipathic molecules exhibit complex behavior when they self-associate and interact with other molecules. The phase behavior and assembled structures of detergents are markedly influenced not only by their unique chemical and physical properties but also by concentration, ionic conditions, and the presence of other lipids and proteins. In this minireview, we discuss the various aggregate forms detergents assume and some misconceptions about their structure. The distinction between detergents and the membrane lipids that they may (or may not) replace is emphasized in the most recent high resolution structures of membrane proteins. Detergents are clearly friends and foes, but with the knowledge of how they work, we can use the increasing variety of detergents to our advantage.
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Affiliation(s)
- R M Garavito
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319, USA.
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73
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Abstract
Life of higher organisms is essentially dependent on the efficient synthesis of ATP by oxidative phosphorylation in mitochondria. An important and as yet unsolved question of energy metabolism is how are the variable rates of ATP synthesis at maximal work load during exercise or mental work and at rest or during sleep regulated. This article reviews our present knowledge on the structure of bacterial and eukaryotic cytochrome c oxidases and correlates it with recent results on the regulatory functions of nuclear-coded subunits of the eukaryotic enzyme, which are absent from the bacterial enzyme. A new molecular hypothesis on the physiological regulation of oxidative phosphorylation is proposed, assuming a hormonally controlled dynamic equilibrium in vivo between two states of energy metabolism, a relaxed state with low ROS (reactive oxygen species) formation, and an excited state with elevated formation of ROS, which are known to accelerate aging and to cause degenerative diseases and cancer. The hypothesis is based on the allosteric ATP inhibition of cytochrome c oxidase at high intramitochondrial ATP/ADP ratios ("second mechanism of respiratory control"), which is switched on by cAMP-dependent phosphorylation and switched off by calcium-induced dephosphorylation of the enzyme.
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Affiliation(s)
- B Ludwig
- Biozentrum, Molekulare Genetik, Johann-Wolfgang-Goethe-Universität Frankfurt, Marie-Curie-Strasse 9, 60439 Frankfurt, Germany
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74
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Videla LA. Energy metabolism, thyroid calorigenesis, and oxidative stress: functional and cytotoxic consequences. Redox Rep 2001; 5:265-75. [PMID: 11145101 DOI: 10.1179/135100000101535807] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Affiliation(s)
- L A Videla
- Programa de Farmacología Molecular y Clínica, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago.
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75
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Kadenbach B, Hüttemann M, Arnold S, Lee I, Bender E. Mitochondrial energy metabolism is regulated via nuclear-coded subunits of cytochrome c oxidase. Free Radic Biol Med 2000; 29:211-21. [PMID: 11035249 DOI: 10.1016/s0891-5849(00)00305-1] [Citation(s) in RCA: 197] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A new mechanism on regulation of mitochondrial energy metabolism is proposed on the basis of reversible control of respiration by the intramitochondrial ATP/ADP ratio and slip of proton pumping (decreased H+/e- stoichiometry) in cytochrome c oxidase (COX) at high proton motive force delta p. cAMP-dependent phosphorylation of COX switches on and Ca2+-dependent dephosphorylation switches off the allosteric ATP-inhibition of COX (nucleotides bind to subunit IV). Control of respiration via phosphorylated COX by the ATP/ADP ratio keeps delta p (mainly delta psi(m)) low. Hormone induced Ca2+-dependent dephosphorylation results in loss of ATP-inhibition, increase of respiration and delta p with consequent slip in proton pumping. Slip in COX increases the free energy of reaction, resulting in increased rates of respiration, thermogenesis and ATP-synthesis. Increased delta psi(m) stimulates production of reactive oxygen species (ROS), mutations of mitochondrial DNA and accelerates aging. Slip of proton pumping without dephosphorylation and increase of delta p is found permanently in the liver-type isozyme of COX (subunit VIaL) and at high intramitochondrial ATP/ADP ratios in the heart-type isozyme (subunit VIaH). High substrate pressure (sigmoidal v/s kinetics), palmitate and 3,5-diiodothyronine (binding to subunit Va) increase also delta p, ROS production and slip but without dephosphorylation of COX.
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Affiliation(s)
- B Kadenbach
- Fachbereich Chemie, Philipps-Universität, Marburg, Germany.
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76
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Hüttemann M, Mühlenbein N, Schmidt TR, Grossman LI, Kadenbach B. Isolation and sequence of the human cytochrome c oxidase subunit VIIaL gene. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1492:252-8. [PMID: 11004498 DOI: 10.1016/s0167-4781(00)00087-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The gene for human cytochrome c oxidase subunit VIIa liver isoform (COX7AL) was isolated and its sequence determined and analyzed. The three introns of the gene are considerably larger than those of the heart isoform of subunit VIIa (COX7AH), but the position of the introns relative to the cDNA sequences is homologous between the two genes. Comparison with other isolated COX7AL genes suggests that the promoter region binding motifs for transcription factors have evolved along with the coding region. In fibroblasts cultured originally from a Leigh's disease patient, a shortened COX7AL cDNA was identified by RT-PCR, consisting of exon I joined to exon IV, omitting exons II and III. No mutation could be identified in COX7AL of the patient, suggesting that the shortened cDNA is due to an alteration of the genome during cell culture. A surprising transcription of COX7AH was observed in cultured fibroblasts, suggesting a potential utility of these cells for study of its gene expression.
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Affiliation(s)
- M Hüttemann
- Fachbereich Chemie, Philipps-Universität, D35032 Marburg, Germany
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77
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Hüttemann M, Arnold S, Lee I, Mühlenbein N, Linder D, Lottspeich F, Kadenbach B. Turkey cytochrome c oxidase contains subunit VIa of the liver type associated with low efficiency of energy transduction. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:2098-104. [PMID: 10727950 DOI: 10.1046/j.1432-1327.2000.01216.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cytochrome c oxidase was isolated from turkey liver, heart and breast skeletal muscle and separated by SDS/PAGE. The N-terminal amino-acid sequence of subunit VIa from all tissues and internal sequences from the skeletal muscle enzyme show homology to the mammalian liver-type subunit VIaL, which was verified by isolation and sequencing of the cDNA of turkey subunit VIa. No cDNA corresponding to subunit VIaH (mammalian heart-type) could be found by RACE-PCR with mRNA from all turkey tissues. Measurement of proton translocation with the reconstituted enzymes from turkey liver and heart revealed H+/e- ratios below 0.5 that were independent of the intraliposomal ATP/ADP ratio, as previously found with the bovine liver enzyme. Under identical conditions, the bovine heart enzyme revealed H+/e- ratios of 0.85 at low and 0.48 at high intraliposomal ATP/ADP ratios. The results suggest that in birds the lower H+/e-ratio of cytochrome c oxidase participates in elevated resting metabolic rate and thermogenesis.
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Affiliation(s)
- M Hüttemann
- Fachbereich Chemie, Philipps-Universität, Marburg, Germany
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78
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Bender E, Kadenbach B. The allosteric ATP-inhibition of cytochrome c oxidase activity is reversibly switched on by cAMP-dependent phosphorylation. FEBS Lett 2000; 466:130-4. [PMID: 10648827 DOI: 10.1016/s0014-5793(99)01773-1] [Citation(s) in RCA: 146] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In previous studies the allosteric inhibition of cytochrome c oxidase at high intramitochondrial ATP/ADP-ratios via binding of the nucleotides to the matrix domain of subunit IV was demonstrated. Here we show that the allosteric ATP-inhibition of the isolated bovine heart enzyme is switched on by cAMP-dependent phosphorylation with protein kinase A of subunits II (and/or III) and Vb, and switched off by subsequent incubation with protein phosphatase 1. It is suggested that after cAMP-dependent phosphorylation of cytochrome c oxidase mitochondrial respiration is controlled by the ATP/ADP-ratio keeping the proton motive force Deltap low, and the efficiency of energy transduction high. After Ca(2+)-induced dephosphorylation this control is lost, accompanied by increase of Deltap, slip of proton pumping (decreased H(+)/e(-) stoichiometry), and increase of the rate of respiration and ATP-synthesis at a decreased efficiency of energy transduction.
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Affiliation(s)
- E Bender
- Fachbereich Chemie, Philipps-Universität, D-35032, Marburg, Germany
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79
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Beauvoit B, Bunoust O, Guérin B, Rigoulet M. ATP-regulation of cytochrome oxidase in yeast mitochondria: role of subunit VIa. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 263:118-27. [PMID: 10429195 DOI: 10.1046/j.1432-1327.1999.00475.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The role of the nuclear-encoded subunit VIa in the regulation of cytochrome oxidase by ATP was investigated in isolated yeast mitochondria. As the subunit VIa-null strain possesses a fully active and assembled cytochrome oxidase, multiple ATP-regulating sites were characterized with respect to their location and their kinetic effect: (a) intra-mitochondrial ATP inhibited the complex IV activity of the null strain, whereas the prevailing effect of ATP on the wild-type strain, at low ionic strength, was activation on the cytosolic side of complex IV, mediated by subunit VIa. However, at physiological ionic strength (i.e. approximately 200 mM), activation by ATP was absent but inhibition was not impaired; (b) in ethanol-respiring mitochondria, when the electron flux was modulated using a protonophoric uncoupler, the redox state of aa3 cytochromes varied with respect to activation (wild-type) or inhibition (null-mutant) of the cytochrome oxidase by ATP; (c) consequently, the control coefficient of cytochrome oxidase on respiratory flux, decreased (wild-type) or increased (null-mutant) in the presence of ATP; (d) considering electron transport from cytochrome c to oxygen, the response of cytochrome oxidase to its thermodynamic driving force was increased by ATP for the wild-type but not for the mutant subunit. Taken together, these findings indicate that at physiological concentration, ATP regulates yeast cytochrome oxidase via subunit-mediated interactions on both sides of the inner membrane, thus subtly tuning the thermodynamic and kinetic control of respiration. This study opens up new prospects for understanding the feedback regulation of the respiratory chain by ATP.
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Affiliation(s)
- B Beauvoit
- Institut de Biochimie et Génétique Cellulaires du CNRS, Université Victor Ségalen, Bordeaux, France.
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80
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Abstract
According to the chemosmotic hypothesis, ATP is synthesized in mitochondria, bacteria and chloroplasts via the proton motive force delta p, the energy-rich intermediate of electron transport and photosynthetic phosphorylation. The general applicability of the chemosmotic hypothesis, however, was disputed until present. In particular the relationship between the rate of respiration and delta p in mitochondria was found variable, depending on the experimental conditions. Recently, a new mechanism of respiratory control was found, based on binding of ATP or ADP to subunit IV of cytochrome c oxidase, which is independent of delta p and could explain many previous results contradicting the chemosmotic hypothesis.
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Affiliation(s)
- B Kadenbach
- Fachbereich Chemie, Philipps-Universität, Marburg, Germany.
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81
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Arnold S, Kadenbach B. The intramitochondrial ATP/ADP-ratio controls cytochrome c oxidase activity allosterically. FEBS Lett 1999; 443:105-8. [PMID: 9989584 DOI: 10.1016/s0014-5793(98)01694-9] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Recently the signal transduction function for oxidative phosphorylation was found to be second order in ADP [Jeneson, J.A.L., Wiseman, R.W., Westerhoff, H.V. and Kushmerick, M.J. (1996) J. Biol. Chem. 271, 27995-279981, but the molecular mechanism of signal transduction remained unclear. Previously we described inhibition of cytochrome c oxidase by intramitochondrial ATP, accompanied by a change of hyperbolic into sigmoidal kinetics. The present study describes a sigmoidal relationship also between the ascorbate respiration of reconstituted cytochrome c oxidase and intraliposomal ADP concentration. Its possible role in the control of oxidative phosphorylation and cell respiration is discussed.
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Affiliation(s)
- S Arnold
- Fachbereich Chemie, Philipps-Universität, Marburg, Germany
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82
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Szewczyk A, Pikuła S. Adenosine 5'-triphosphate: an intracellular metabolic messenger. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1365:333-53. [PMID: 9711292 DOI: 10.1016/s0005-2728(98)00094-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- A Szewczyk
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Warsaw, Poland.
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83
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Napiwotzki J, Kadenbach B. Extramitochondrial ATP/ADP-ratios regulate cytochrome c oxidase activity via binding to the cytosolic domain of subunit IV. Biol Chem 1998; 379:335-9. [PMID: 9563830 DOI: 10.1515/bchm.1998.379.3.335] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cytochrome c oxidase from bovine heart contains seven binding sites for ATP or ADP and three additional for ADP only, as concluded from competition equilibrium dialysis binding studies. The isolated enzyme contains bound cholate which, in contrast to bound ATP, is only slowly exchanged by ADP (or ATP). The kinetics of the reconstituted enzyme is influenced by extraliposomal (cytosolic) ATP and ADP. The Km for cytochrome c is five times higher in the presence of extraliposomal ATP than of ADP. These differences of Km values are lost after preincubation of the enzyme with a monoclonal antibody to subunit IV. The data demonstrate regulation of cytochrome c oxidase activity by the cytosolic ATP/ADP-ratio, in addition to regulation by the matrix ATP/ADP-ratio [Arnold and Kadenbach (1997) Eur. J. Biochem. 249, 350- 354], both interacting with subunit IV.
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Affiliation(s)
- J Napiwotzki
- Fachbereich Chemie, Philipps-Universität, Marburg, Germany
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84
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Kadenbach B, Napiwotzki J, Frank V, Arnold S, Exner S, Hüttemann M. Regulation of energy transduction and electron transfer in cytochrome c oxidase by adenine nucleotides. J Bioenerg Biomembr 1998; 30:25-33. [PMID: 9623802 DOI: 10.1023/a:1020599209468] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cytochrome c oxidase from bovine heart contains seven high-affinity binding sites for ATP or ADP and three additional only for ADP. One binding site for ATP or ADP, located at the matrix-oriented domain of the heart-type subunit VIaH, increases the H+/e- stoichiometry of the enzyme from heart or skeletal muscle from 0.5 to 1.0 when bound ATP is exchanged by ADP. Two further binding sites for ATP or ADP, located at the cytosolic and the matrix domain of subunit IV, increases the K(M) for cytochrome c and inhibit the respiratory activity at high ATP/ADP ratios, respectively. We propose that thermogenesis in mammals is related to subunit VIaL of cytochrome c oxidase with a H+/e- stoichiometry of 0.5 compared to 1.0 in the enzyme from bacteria or ectotherm animals. This hypothesis is supported by the lack of subunit VIa isoforms in cytochrome c oxidase from fish.
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Affiliation(s)
- B Kadenbach
- Fachbereich Chemie, Philipps-Universität, Marburg, Germany
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85
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Arnold S, Kadenbach B. Cell respiration is controlled by ATP, an allosteric inhibitor of cytochrome-c oxidase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 249:350-4. [PMID: 9363790 DOI: 10.1111/j.1432-1033.1997.t01-1-00350.x] [Citation(s) in RCA: 185] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The activity of cytochrome-c oxidase, the terminal enzyme of the mitochondrial respiratory chain, is known to be regulated by the substrate pressure, i.e. the ferro-/ferricytochrome c ratio, by the oxygen concentration, and by the electrochemical proton gradient delta muH+ across the inner mitochondrial membrane. Here we describe a further mechanism of 'respiratory control' via allosteric inhibition of cytochrome-c oxidase by ATP, which binds to the matrix domain, of subunit IV. The cooperativity between cytochrome-c-binding sites in the dimeric enzyme complex is mediated by cardiolipin, which is essential for cooperativity of the enzyme within the lipid membrane.
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Affiliation(s)
- S Arnold
- Fachbereich Chemie, Philipps-Universität, Marburg, Germany
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