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Barreto P, Couñago RM, Arruda P. Mitochondrial uncoupling protein-dependent signaling in plant bioenergetics and stress response. Mitochondrion 2020; 53:109-120. [DOI: 10.1016/j.mito.2020.05.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 04/06/2020] [Accepted: 05/14/2020] [Indexed: 12/15/2022]
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2
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Lee CP, Maksaev G, Jensen GS, Murcha MW, Wilson ME, Fricker M, Hell R, Haswell ES, Millar AH, Sweetlove LJ. MSL1 is a mechanosensitive ion channel that dissipates mitochondrial membrane potential and maintains redox homeostasis in mitochondria during abiotic stress. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2016; 88:809-825. [PMID: 27505616 PMCID: PMC5195915 DOI: 10.1111/tpj.13301] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 08/04/2016] [Accepted: 08/05/2016] [Indexed: 05/18/2023]
Abstract
Mitochondria must maintain tight control over the electrochemical gradient across their inner membrane to allow ATP synthesis while maintaining a redox-balanced electron transport chain and avoiding excessive reactive oxygen species production. However, there is a scarcity of knowledge about the ion transporters in the inner mitochondrial membrane that contribute to control of membrane potential. We show that loss of MSL1, a member of a family of mechanosensitive ion channels related to the bacterial channel MscS, leads to increased membrane potential of Arabidopsis mitochondria under specific bioenergetic states. We demonstrate that MSL1 localises to the inner mitochondrial membrane. When expressed in Escherichia coli, MSL1 forms a stretch-activated ion channel with a slight preference for anions and provides protection against hypo-osmotic shock. In contrast, loss of MSL1 in Arabidopsis did not prevent swelling of isolated mitochondria in hypo-osmotic conditions. Instead, our data suggest that ion transport by MSL1 leads to dissipation of mitochondrial membrane potential when it becomes too high. The importance of MSL1 function was demonstrated by the observation of a higher oxidation state of the mitochondrial glutathione pool in msl1-1 mutants under moderate heat- and heavy-metal-stress. Furthermore, we show that MSL1 function is not directly implicated in mitochondrial membrane potential pulsing, but is complementary and appears to be important under similar conditions.
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Affiliation(s)
- Chun Pong Lee
- ARC Centre of Excellence in Plant Energy Biology, University of Western Australia, Bayliss Building M316, 35 Stirling Highway, Crawley, 6009, Western Australia, Australia
| | - Grigory Maksaev
- Department of Biology, Washington University in Saint Louis, One Brookings Drive, Mailcode 1137, Saint Louis, MO, 63130, USA
| | - Gregory S Jensen
- Department of Biology, Washington University in Saint Louis, One Brookings Drive, Mailcode 1137, Saint Louis, MO, 63130, USA
| | - Monika W Murcha
- ARC Centre of Excellence in Plant Energy Biology, University of Western Australia, Bayliss Building M316, 35 Stirling Highway, Crawley, 6009, Western Australia, Australia
| | - Margaret E Wilson
- Department of Biology, Washington University in Saint Louis, One Brookings Drive, Mailcode 1137, Saint Louis, MO, 63130, USA
| | - Mark Fricker
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK
| | - Ruediger Hell
- Department of Plant Molecular Biology, Centre for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 360, D-69120, Heidelberg, Germany
| | - Elizabeth S Haswell
- Department of Biology, Washington University in Saint Louis, One Brookings Drive, Mailcode 1137, Saint Louis, MO, 63130, USA
| | - A Harvey Millar
- ARC Centre of Excellence in Plant Energy Biology, University of Western Australia, Bayliss Building M316, 35 Stirling Highway, Crawley, 6009, Western Australia, Australia
| | - Lee J Sweetlove
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK
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Oliveira MG, Mazorra LM, Souza AF, Silva GMC, Correa SF, Santos WC, Saraiva KDC, Teixeira AJ, Melo DF, Silva MG, Silva MAP, Arrabaça JDC, Costa JH, Oliveira JG. Involvement of AOX and UCP pathways in the post-harvest ripening of papaya fruits. JOURNAL OF PLANT PHYSIOLOGY 2015; 189:42-50. [PMID: 26513459 DOI: 10.1016/j.jplph.2015.10.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 09/25/2015] [Accepted: 10/01/2015] [Indexed: 06/05/2023]
Abstract
Enhanced respiration during ripening in climacteric fruits is sometimes associated with an uncoupling between the ATP synthesis and the mitochondrial electron transport chain. While the participation of two energy-dissipating systems, one of which is mediated by the alternative oxidase (AOX) and the other mediated by the uncoupling protein (UCP), has been linked to fruit ripening, the relation between the activation of both mitochondrial uncoupling systems with the transient increase of ethylene synthesis (ethylene peak) remains unclear. To elucidate this question, ethylene emission and the two uncoupling (AOX and UCP) pathways were monitored in harvested papaya fruit during the ripening, from green to fully yellow skin. The results confirmed the typical climacteric behavior for papaya fruit: an initial increase in endogenous ethylene emission which reaches a maximum (peak) in the intermediate ripening stage, before finally declining to a basal level in ripe fruit. Respiration of intact fruit also increased and achieved higher levels at the end of ripening. On the other hand, in purified mitochondria extracted from fruit pulp the total respiration and respiratory control decrease while an increase in the participation of AOX and UCP pathways was markedly evident during papaya ripening. There was an increase in the AOX capacity during the transition from green fruit to the intermediate stage that accompanied the transient ethylene peak, while the O2 consumption triggered by UCP activation increased by 80% from the beginning to end stage of fruit ripening. Expression analyses of AOX (AOX1 and 2) and UCP (UCP1-5) genes revealed that the increases in the AOX and UCP capacities were linked to a higher expression of AOX1 and UCP (mainly UCP1) genes, respectively. In silico promoter analyses of both genes showed the presence of ethylene-responsive cis-elements in UCP1 and UCP2 genes. Overall, the data suggest a differential activation of AOX and UCP pathways in regulation related to the ethylene peak and induction of specific genes such as AOX1 and UCP1.
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Affiliation(s)
- M G Oliveira
- Laboratório de Melhoramento Genético Vegetal, Centro de Ciências e Tecnologias Agropecuárias, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ 28013602, Brazil
| | - L M Mazorra
- Laboratório de Melhoramento Genético Vegetal, Centro de Ciências e Tecnologias Agropecuárias, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ 28013602, Brazil
| | - A F Souza
- Laboratório de Melhoramento Genético Vegetal, Centro de Ciências e Tecnologias Agropecuárias, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ 28013602, Brazil
| | - G M C Silva
- Laboratório de Melhoramento Genético Vegetal, Centro de Ciências e Tecnologias Agropecuárias, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ 28013602, Brazil
| | - S F Correa
- Laboratório de Ciências Físicas, Universidade Estadual no Norte Fluminense, Campos dos Goytacazes, RJ 28013602, Brazil
| | - W C Santos
- Laboratório de Ciências Físicas, Universidade Estadual no Norte Fluminense, Campos dos Goytacazes, RJ 28013602, Brazil
| | - K D C Saraiva
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, Fortaleza, CE 60455760, Brazil
| | - A J Teixeira
- Laboratório de Melhoramento Genético Vegetal, Centro de Ciências e Tecnologias Agropecuárias, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ 28013602, Brazil
| | - D F Melo
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, Fortaleza, CE 60455760, Brazil
| | - M G Silva
- Laboratório de Ciências Físicas, Universidade Estadual no Norte Fluminense, Campos dos Goytacazes, RJ 28013602, Brazil
| | - M A P Silva
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, MG 36570000, Brazil
| | - J D C Arrabaça
- Faculdade de Ciências, Universidade de Lisboa, Lisboa 1749016, Portugal
| | - J H Costa
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, Fortaleza, CE 60455760, Brazil
| | - J G Oliveira
- Laboratório de Melhoramento Genético Vegetal, Centro de Ciências e Tecnologias Agropecuárias, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ 28013602, Brazil.
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Jastroch M, Hirschberg V, Klingenspor M. Functional characterization of UCP1 in mammalian HEK293 cells excludes mitochondrial uncoupling artefacts and reveals no contribution to basal proton leak. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:1660-70. [PMID: 22676960 DOI: 10.1016/j.bbabio.2012.05.014] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Revised: 05/22/2012] [Accepted: 05/28/2012] [Indexed: 02/02/2023]
Abstract
Mechanistic studies on uncoupling proteins (UCPs) not only are important to identify their cellular function but also are pivotal to identify potential drug targets to manipulate mitochondrial energy transduction. So far, functional and comparative studies of uncoupling proteins in their native environment are hampered by different mitochondrial, cellular and genetic backgrounds. Artificial systems such as yeast ectopically expressing UCPs or liposomes with reconstituted UCPs were employed to address crucial mechanistic questions but these systems also produced inconsistencies with results from native mitochondria. We here introduce a novel mammalian cell culture system (Human Embryonic Kidney 293 - HEK293) to study UCP1 function. Stably transfected HEK293 cell lines were derived that contain mouse UCP1 at concentrations comparable to tissue mitochondria. In this cell-based test system UCP1 displays native functional behaviour as it can be activated with fatty acids (palmitate) and inhibited with purine nucleotides guanosine-diphosphate (GDP). The catalytic centre activity of the UCP1 homodimer in HEK293 is comparable to activities in brown adipose tissue supporting functionality of UCP1. Importantly, at higher protein levels than in yeast mitochondria, UCP1 in HEK293 cell mitochondria is fully inhibitable and does not contribute to basal proton conductance, thereby emphasizing the requirement of UCP1 activation for therapeutic purposes. These findings and resulting analysis on UCP1 characteristics demonstrate that the mammalian HEK293 cell system is suitable for mechanistic and comparative functional studies on UCPs and provides a non-confounding mitochondrial, cellular and genetic background.
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Affiliation(s)
- Martin Jastroch
- Institute for Diabetes and Obesity, Helmholtz Zentrum Munich, Neuherberg, Germany.
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Divakaruni AS, Brand MD. The regulation and physiology of mitochondrial proton leak. Physiology (Bethesda) 2011; 26:192-205. [PMID: 21670165 DOI: 10.1152/physiol.00046.2010] [Citation(s) in RCA: 289] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Mitochondria couple respiration to ATP synthesis through an electrochemical proton gradient. Proton leak across the inner membrane allows adjustment of the coupling efficiency. The aim of this review is threefold: 1) introduce the unfamiliar reader to proton leak and its physiological significance, 2) review the role and regulation of uncoupling proteins, and 3) outline the prospects of proton leak as an avenue to treat obesity, diabetes, and age-related disease.
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Affiliation(s)
- Ajit S Divakaruni
- Medical Research Council Mitochondrial Biology Unit, Wellcome Trust/MRC Building, Cambridge, United Kingdom
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Laus MN, Soccio M, Trono D, Liberatore MT, Pastore D. Activation of the plant mitochondrial potassium channel by free fatty acids and acyl-CoA esters: a possible defence mechanism in the response to hyperosmotic stress. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:141-54. [PMID: 20801915 DOI: 10.1093/jxb/erq256] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The effect of free fatty acids (FFAs) and acyl-CoA esters on K(+) uptake was studied in mitochondria isolated from durum wheat (Triticum durum Desf.), a species that has adapted well to the semi-arid Mediterranean area and possessing a highly active mitochondrial ATP-sensitive K(+) channel (PmitoK(ATP)), that may confer resistance to environmental stresses. This was made by swelling experiments in KCl solution under experimental conditions in which PmitoK(ATP) activity was monitored. Linoleate and other FFAs (laurate, palmitate, stearate, palmitoleate, oleate, arachidonate, and the non-physiological 1-undecanesulphonate and 5-phenylvalerate), used at a concentration (10 μM) unable to damage membranes of isolated mitochondria, stimulated K(+) uptake by about 2-4-fold. Acyl-CoAs also promoted K(+) transport to a much larger extent with respect to FFAs (about 5-12-fold). In a different experimental system based on safranin O fluorescence measurements, the dissipation of electrical membrane potential induced by K(+) uptake via PmitoK(ATP) was found to increase in the presence of 5-phenylvalerate and palmitoyl-CoA, both unable to elicit the activity of the Plant Uncoupling Protein. This result suggests a direct activation of PmitoK(ATP). Stimulation of K(+) transport by FFAs/acyl-CoAs resulted in a widespread phenomenon in plant mitochondria from different mono/dicotyledonous species (bread wheat, barley, triticale, maize, lentil, pea, and topinambur) and from different organs (root, tuber, leaf, and shoot). Finally, an increase in mitochondrial FFAs up to a content of 50 nmol mg(-1) protein, which was able to activate PmitoK(ATP) strongly, was observed under hyperosmotic stress conditions. Since PmitoK(ATP) may act against environmental/oxidative stress, its activation by FFAs/acyl-CoAs is proposed to represent a physiological defence mechanism.
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Affiliation(s)
- Maura N Laus
- Dipartimento di Scienze Agro-ambientali, Chimica e Difesa Vegetale, Facoltà di Agraria, Università degli Studi di Foggia, Via Napoli, 25-71122 Foggia, Italy
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Jezek P, Jabůrek M, Garlid KD. Channel character of uncoupling protein-mediated transport. FEBS Lett 2010; 584:2135-41. [PMID: 20206627 DOI: 10.1016/j.febslet.2010.02.068] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Revised: 02/23/2010] [Accepted: 02/26/2010] [Indexed: 11/15/2022]
Abstract
Mitochondrial uncoupling proteins (UCPs) are pure anion uniporters, which mediate fatty acid (FA) uniport leading to FA cycling. Protonated FAs then flip-flop back across the lipid bilayer. An existence of pure proton channel in UCPs is excluded by the equivalent flux-voltage dependencies for uniport of FAs and halide anions, which are best described by the Eyring barrier variant with a single energy well in the middle of two peaks. Experiments with FAs unable to flip and alkylsulfonates also support this view. Phylogenetically, UCPs took advantage of the common FA-uncoupling function of SLC25 family carriers and dropped their solute transport function.
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Affiliation(s)
- Petr Jezek
- Department of Membrane Transport Biophysics, No. 75, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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Jezek P, Zácková M, Kosarová J, Rodrigues ET, Madeira VM, Vicente JA. Occurrence of plant-uncoupling mitochondrial protein (PUMP) in diverse organs and tissues of several plants. J Bioenerg Biomembr 2009; 32:549-61. [PMID: 15254369 DOI: 10.1023/a:1005648226431] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The presence of plant-uncoupling mitochondrial protein (PUMP), previously described by Vercesi et al. (1995), was screened in mitochondria of various organs or tissues of several plant species. This was done functionally, by monitoring purine nucleotide-sensitive linoleic acid-induced uncoupling, or by Western blots. The following findings were established: (1) PUMP was found in most of the higher plants tested; (2) since ATP inhibition of linoleic acid-induced membrane potential decrease varied, PUMP content might differ in different plant tissues, as observed with mitochondria from maize roots, maize seeds, spinach leaves, wheat shoots, carrot roots, cauliflower, broccoli, maize shoots, turnip root, and potato calli. Western blots also indicated PUMP presence in oat shoots, carnation petals, onion bulbs, red beet root, green cabbage, and Sedum leaves. (3) PUMP was not detected in mushrooms. We conclude that PUMP is likely present in the mitochondria of organs and tissues of all higher plants.
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Affiliation(s)
- P Jezek
- Department of Membrane Transport Biophysics, Institute of Physiology, Academy of Sciences, Prague, Czech Republic.
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Dlasková A, Spacek T, Skobisová E, Santorová J, Jezek P. Certain aspects of uncoupling due to mitochondrial uncoupling proteins in vitro and in vivo. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:467-73. [PMID: 16781660 DOI: 10.1016/j.bbabio.2006.05.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2006] [Revised: 04/21/2006] [Accepted: 05/05/2006] [Indexed: 01/12/2023]
Abstract
Thermogenic uncoupling has been proven only for UCP1 in brown adipose tissue. All other isoforms of UCPs are potentially acting in suppression of mitochondrial reactive oxygen species (ROS) production. In this contribution we show that BAT mitochondria can be uncoupled by lauric acid in the range of approximately 100 nM when endogenous fatty acids are combusted by carnitine cycle and beta-oxidation is properly separated from the uncoupling effect. Respiration increased up to 3 times when related to the lowest fatty acid content (BSA present plus carnitine cycle). We also illustrated that any effect leading to more coupled states leads to enhanced H2O2 generation and any effect resulting in uncoupling gives reduced H2O2 generation in BAT mitochondria. Finally, we report doubling of plant UCP transcript in cells as well as amount of protein detected by 3H-GTP-binding sites in mitochondria of shoots and roots of maize seedlings subjected to the salt stress.
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Affiliation(s)
- Andrea Dlasková
- Department No.75, Membrane Transport Biophysics, Institute of Physiology, Academy of Sciences of the Czech Republic, Vídenská 1083, 14220 Prague 4, Czech Republic
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Fávaro RD, Borecký J, Colombi D, Maia IG. ZmPUMP encodes a fully functional monocot plant uncoupling mitochondrial protein whose affinity to fatty acid is increased with the introduction of a His pair at the second matrix loop. Biochem Biophys Res Commun 2006; 344:194-9. [PMID: 16603126 DOI: 10.1016/j.bbrc.2006.03.132] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2006] [Accepted: 03/20/2006] [Indexed: 11/25/2022]
Abstract
Uncoupling proteins (UCPs) are specialized mitochondrial transporter proteins that uncouple respiration from ATP synthesis. In this study, cDNA encoding maize uncoupling protein (ZmPUMP) was expressed in Escherichia coli and recombinant ZmPUMP reconstituted in liposomes. ZmPUMP activity was associated with a linoleic acid (LA)-mediated H(+) efflux with K(m) of 56.36+/-0.27microM and V(max) of 66.9micromolH(+)min(-1)(mgprot)(-1). LA-mediated H(+) fluxes were sensitive to ATP inhibition with K(i) of 2.61+/-0.36mM (at pH 7.2), a value similar to those for dicot UCPs. ZmPUMP was also used to investigate the importance of a histidine pair present in the second matrix loop of mammalian UCP1 and absent in plant UCPs. ZmPUMP with introduced His pair (Lys155His and Ala157His) displayed a 1.55-fold increase in LA-affinity while its activity remained unchanged. Our data indicate conserved properties of plant UCPs and suggest an enhancing but not essential role of the histidine pair in proton transport mechanism.
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Affiliation(s)
- J Enrique Silva
- Department of Medicine, Division of Endocrinology, Jewish General Hospital, McGill University, Montreal, Canada
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Borecky J, Nogueira FTS, de Oliveira KAP, Maia IG, Vercesi AE, Arruda P. The plant energy-dissipating mitochondrial systems: depicting the genomic structure and the expression profiles of the gene families of uncoupling protein and alternative oxidase in monocots and dicots. JOURNAL OF EXPERIMENTAL BOTANY 2006; 57:849-64. [PMID: 16473895 DOI: 10.1093/jxb/erj070] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The simultaneous existence of alternative oxidases and uncoupling proteins in plants has raised the question as to why plants need two energy-dissipating systems with apparently similar physiological functions. A probably complete plant uncoupling protein gene family is described and the expression profiles of this family compared with the multigene family of alternative oxidases in Arabidopsis thaliana and sugarcane (Saccharum sp.) employed as dicot and monocot models, respectively. In total, six uncoupling protein genes, AtPUMP1-6, were recognized within the Arabidopsis genome and five (SsPUMP1-5) in a sugarcane EST database. The recombinant AtPUMP5 protein displayed similar biochemical properties as AtPUMP1. Sugarcane possessed four Arabidopsis AOx1-type orthologues (SsAOx1a-1d); no sugarcane orthologue corresponding to Arabidopsis AOx2-type genes was identified. Phylogenetic and expression analyses suggested that AtAOx1d does not belong to the AOx1-type family but forms a new (AOx3-type) family. Tissue-enriched expression profiling revealed that uncoupling protein genes were expressed more ubiquitously than the alternative oxidase genes. Distinct expression patterns among gene family members were observed between monocots and dicots and during chilling stress. These findings suggest that the members of each energy-dissipating system are subject to different cell or tissue/organ transcriptional regulation. As a result, plants may respond more flexibly to adverse biotic and abiotic conditions, in which oxidative stress is involved.
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Affiliation(s)
- Jirí Borecky
- Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, UNICAMP, CP 6109, 13083-970, Campinas, SP, Brazil
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Vercesi AE, Borecký J, Maia IDG, Arruda P, Cuccovia IM, Chaimovich H. Plant uncoupling mitochondrial proteins. ANNUAL REVIEW OF PLANT BIOLOGY 2006; 57:383-404. [PMID: 16669767 DOI: 10.1146/annurev.arplant.57.032905.105335] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Uncoupling proteins (UCPs) are membrane proteins that mediate purine nucleotide-sensitive free fatty acid-activated H(+) flux through the inner mitochondrial membrane. After the discovery of UCP in higher plants in 1995, it was acknowledged that these proteins are widely distributed in eukaryotic organisms. The widespread presence of UCPs in eukaryotes implies that these proteins may have functions other than thermogenesis. In this review, we describe the current knowledge of plant UCPs, including their discovery, biochemical properties, distribution, gene family, gene expression profiles, regulation of gene expression, and evolutionary aspects. Expression analyses and functional studies on the plant UCPs under normal and stressful conditions suggest that UCPs regulate energy metabolism in the cellular responses to stress through regulation of the electrochemical proton potential (Deltamu(H)+) and production of reactive oxygen species.
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Affiliation(s)
- Aníbal Eugênio Vercesi
- Laboratório de Bioenergética, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP), 13083-970, Campinas, SP, Brazil.
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Paventi G, Pastore D, Bobba A, Pizzuto R, Di Pede S, Passarella S. Plant uncoupling protein in mitochondria from aged-dehydrated slices of Jerusalem artichoke tubers becomes sensitive to superoxide and to hydrogen peroxide without increase in protein level. Biochimie 2005; 88:179-88. [PMID: 16181725 DOI: 10.1016/j.biochi.2005.07.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2005] [Accepted: 07/27/2005] [Indexed: 11/17/2022]
Abstract
We investigated the occurrence of the plant Uncoupling Protein (UCP) in mitochondria isolated from both fresh (f-JAM) and aged-dehydrated (a-d-JAM) slices of Jerusalem artichoke tubers (Helianthus tuberosus L.). The presence of UCP was shown by immunological analysis and its function was investigated by measuring the decrease of the mitochondrial membrane potential due to linoleic acid (LA) and its inhibition by purine nucleotides under conditions in which the adenine nucleotide translocator (ANT) was inhibited by atractyloside (Atr). f-JAM and a-d-JAM had the same protein content, but differed from one another with respect to purine nucleotide inhibition, substrate specificity, and sensitivity to ROS. Hydrogen peroxide and superoxide anion, generated in situ by xanthine plus xanthine oxidase, caused a significant increase in the UCP function in a-d-JAM, but not in f-JAM. This occurred in a manner sensitive to ATP, but not to Atr, thus showing that ANT has no role in the process. The dependence of the rate of membrane potential decrease on increasing LA concentrations, either in the absence or the presence of ROS, showed a sigmoidal saturation both in f-JAM and a-d-JAM. However, addition of ROS in a-d-JAM resulted in about 40% increase of the Vmax value, with no change in the K0.5 (about 20 microM), whereas in f-JAM no effect on either the Vmax or K0.5 (about 28 microM) was found. Furthermore, a decreased ROS production as a result of LA addition was found in both f-JAM and a-d-JAM, the effect being more marked in a-d-JAM.
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Affiliation(s)
- Gianluca Paventi
- Dipartimento di Scienze Animali, Vegetali e dell'Ambiente, Facoltà di Agraria, Università del Molise, Via De Sanctis, 86100 Campobasso, Italy
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Borecký J, Vercesi AE. Plant Uncoupling Mitochondrial Protein and Alternative Oxidase: Energy Metabolism and Stress. Biosci Rep 2005; 25:271-86. [PMID: 16283557 DOI: 10.1007/s10540-005-2889-2] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Energy-dissipation in plant mitochondria can be mediated by inner membrane proteins via two processes: redox potential-dissipation or proton electrochemical potential-dissipation. Alternative oxidases (AOx) and the plant uncoupling mitochondrial proteins (PUMP) perform a type of intrinsic and extrinsic regulation of the coupling between respiration and phosphorylation, respectively. Expression analyses and functional studies on AOx and PUMP under normal and stress conditions suggest that the physiological role of both systems lies most likely in tuning up the mitochondrial energy metabolism in response of cells to stress situations. Indeed, the expression and function of these proteins in non-thermogenic tissues suggest that their primary functions are not related to heat production.
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Affiliation(s)
- Jirí Borecký
- Departamento de Patologia Clínica (NMCE), FCM, Universidade Estadual de Campinas (UNICAMP), CP 6111, 13083-970 Campinas, SP, Brazil
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Jarmuszkiewicz W, Navet R, Alberici LC, Douette P, Sluse-Goffart CM, Sluse FE, Vercesi AE. Redox state of endogenous coenzyme q modulates the inhibition of linoleic acid-induced uncoupling by guanosine triphosphate in isolated skeletal muscle mitochondria. J Bioenerg Biomembr 2005; 36:493-502. [PMID: 15534396 DOI: 10.1023/b:jobb.0000047331.25248.7a] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The skeletal muscle mitochondria contain two isoforms of uncoupling protein, UCP2 and mainly UCP3, which had been shown to be activated by free fatty acids and inhibited by purine nucleotides in reconstituted systems. On the contrary in isolated mitochondria, the protonophoretic action of muscle UCPs had failed to be demonstrated in the absence of superoxide production. We showed here for the first time that muscle UCPs were activated in state 3 respiration by linoleic acid and dissipated energy from oxidative phosphorylation by decreasing the ADP/O ratio. The efficiency of UCPs in mitochondrial uncoupling increased when the state 3 respiratory rate decreased. The inhibition of the linoleic acid-induced uncoupling by a purine nucleotide (GTP), was not observed in state 4 respiration, in uninhibited state 3 respiration, as well as in state 3 respiration inhibited by complex III inhibitors. On the contrary, the progressive inhibition of state 3 respiration by n -butyl malonate, which inhibits the uptake of succinate, led to a full inhibitory effect of GTP. Therefore, as the inhibitory effect of GTP was observed only when the reduced state of coenzyme Q was decreased, we propose that the coenzyme Q redox state could be a metabolic sensor that modulates the purine nucleotide inhibition of FFA-activated UCPs in muscle mitochondria.
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17
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Dridi S, Onagbesan O, Swennen Q, Buyse J, Decuypere E, Taouis M. Gene expression, tissue distribution and potential physiological role of uncoupling protein in avian species. Comp Biochem Physiol A Mol Integr Physiol 2004; 139:273-83. [PMID: 15556382 DOI: 10.1016/j.cbpb.2004.09.010] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2004] [Revised: 09/13/2004] [Accepted: 09/15/2004] [Indexed: 11/23/2022]
Abstract
Whole-body energy homeostasis and food intake control are essential for an economically sound selection for growth in poultry. The cellular and molecular mechanisms that regulate and link food intake, energy expenditure and energy balance are still poorly understood in poultry. Mitochondrial uncoupling protein-1 (UCP-1) is known to uncouple respiration from ATP synthesis by short circuiting the inward proton flow, resulting in heat production. Its role seems quite well established in adaptive thermogenesis and energy metabolism. However, uncertainty still surrounds the physiological function of the recently discovered UCP-1 homologues, UCP-2 and -3. Most of the functional characterization of these UCPs, to date, has been conducted in mammals. Recently, an avian UCP homologue, which was identified in chicken, hummingbird and king penguin, appears to play a key role in adaptative thermogenesis. Here, we review recent reports describing avian UCP (av-UCP) and discuss progress concerning the molecular mechanisms and potential role of the av-UCP in thermogenesis regulation in avian species.
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Affiliation(s)
- Sami Dridi
- Laboratory of Physiology and Immunology of Domestic Animals, Department of Animal Production, Katholieke Universiteit Leuven, B-3001 Leuven, Belgium.
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18
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Calegario FF, Cosso RG, Fagian MM, Almeida FV, Jardim WF, Jezek P, Arruda P, Vercesi AE. Stimulation of potato tuber respiration by cold stress is associated with an increased capacity of both plant uncoupling mitochondrial protein (PUMP) and alternative oxidase. J Bioenerg Biomembr 2004; 35:211-20. [PMID: 13678272 DOI: 10.1023/a:1024655514113] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The CO2 evolution of intact potato tubers (Solanum tuberosum, L., var. "Bintje") was analyzed during a 10-day period of their warm (25 +/- 2 degrees C) or cold (5 +/- 1 degrees C) storage, to evaluate cold-stress effects on expression and activities of plant uncoupling mitochondrial protein (PUMP) and alternative oxidase (AOX). CO2 evolution rates were analyzed at 20 degrees C, to reflect their possible capacities. The 20 degrees C CO2 production declined from 13 to 8 mg kg(-1) h(-1) after 2 days of warm storage and then (after 3 to 7 days) decreased from 8 to 6.5 mg kg(-1) h(-1). In contrast, 20 degrees C CO2 evolution did not change after the first day of cold storage, increased up to 14.5 mg kg(-1) h(-1) after 2 days, and decreased to about 12 mg kg(-1) h(-1) after 3 to 7 days of cold storage. Cold storage increased PUMP expression as detected by Western blots and led to elevated capacities of both PUMP (44%) and CN-resistant AOX (10 times), but not the cytochrome pathway. Since we found that cold storage led to about the same mitochondrial respiration of 40 nmol O2 min(-1) mg(-1) attributable to each of the respective proteins, we conclude that both AOX and PUMP equally contribute to adaptation of potato tubers to cold.
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Affiliation(s)
- Fagoni Fayer Calegario
- Departamento de Patologia Clínica, NMCE, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, 13083-970, Campinas, SP, Brazil
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19
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Hourton-Cabassa C, Rita Matos A, Zachowski A, Moreau F. The plant uncoupling protein homologues: a new family of energy-dissipating proteins in plant mitochondria. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2004; 42:283-90. [PMID: 15120112 DOI: 10.1016/j.plaphy.2004.01.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2003] [Accepted: 01/30/2004] [Indexed: 05/19/2023]
Abstract
Uncoupling proteins (UCPs) form a subfamily within the mitochondrial carrier protein family, which catalyze a free fatty acid-mediated proton recycling and can modulate the tightness of coupling between mitochondrial respiration and ATP synthesis. As in mammalian tissues, UCPs are rather ubiquitous in the plant kingdom and widespread in plant tissues in which they could have various physiological roles, such as heat production or protection against free oxygen radicals. The simultaneous occurrence in plant mitochondria of two putative energy-dissipating systems, namely UCP which dissipates the proton motive force, and alternative oxidase (AOX) which dissipates the redox potential, raises the question of their functional interactions.
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Affiliation(s)
- Cécile Hourton-Cabassa
- Laboratoire de Physiologie Cellulaire et Moléculaire des Plantes, Université Pierre et Marie Curie, CNRS, UMR 7632, case 154, 4 place Jussieu, 75252 Paris cedex 5, France.
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20
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Finnegan PM, Soole KL, Umbach AL. Alternative Mitochondrial Electron Transport Proteins in Higher Plants. PLANT MITOCHONDRIA: FROM GENOME TO FUNCTION 2004. [DOI: 10.1007/978-1-4020-2400-9_9] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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21
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22
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Grabelnych O, Kolesnichenko A, Pobezhimova T, Tourchaninova V, Korzun A, Koroleva N, Zykova V, Voinikov V. The role of different plant seedling shoots mitochondrial uncoupling systems in thermogenesis during low-temperature stress. J Therm Biol 2003. [DOI: 10.1016/j.jtherbio.2003.08.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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23
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Considine MJ, Goodman M, Echtay KS, Laloi M, Whelan J, Brand MD, Sweetlove LJ. Superoxide stimulates a proton leak in potato mitochondria that is related to the activity of uncoupling protein. J Biol Chem 2003; 278:22298-302. [PMID: 12672801 DOI: 10.1074/jbc.m301075200] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The ability of plant mitochondrial uncoupling proteins to catalyze a significant proton conductance in situ is controversial. We have re-examined conditions that lead to uncoupling of mitochondria isolated from the tubers of potato (Solanum tuberosum). Specifically, we have investigated the effect of superoxide. In the absence of superoxide, linoleic acid stimulated a proton leak in mitochondria respiring NADH that was insensitive to GTP. However, when exogenous superoxide was generated by the addition of xanthine and xanthine oxidase, there was an additional linoleic acid-stimulated proton leak that was specifically inhibited by GTP. Under these conditions of assay (NADH as a respiratory substrate, in the presence of linoleic acid and xanthine/xanthine oxidase) there was a higher rate of proton conductance in mitochondria from transgenic potato tubers overexpressing the StUCP gene than those from wild type. The increased proton leak in the transgenic mitochondria was completely abolished by the addition of GTP. This suggests that superoxide and linoleic acid stimulate a proton leak in potato mitochondria that is related to the activity of uncoupling protein. Furthermore, it demonstrates that changes in the amount of StUCP can alter the rate of proton conductance of potato mitochondria.
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Affiliation(s)
- Michael J Considine
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, United Kingdom
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24
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Zackova M, Skobisová E, Urbánková E, Jezek P. Activating omega-6 polyunsaturated fatty acids and inhibitory purine nucleotides are high affinity ligands for novel mitochondrial uncoupling proteins UCP2 and UCP3. J Biol Chem 2003; 278:20761-9. [PMID: 12670931 DOI: 10.1074/jbc.m212850200] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
UCP2 (the lowest Km values: 20 and 29 microm, respectively) for omega-6 polyunsaturated FAs (PUFAs), all-cis-8,11,14-eicosatrienoic and all-cis-6,9,12-octadecatrienoic acids, which are also the most potent agonists of the nuclear PPARbeta receptor in the activation of UCP2 transcription. omega-3 PUFA, cis-5,8,11,14,17-eicosapentaenoic acid had lower affinity (Km, 50 microm), although as an omega-6 PUFA, arachidonic acid exhibited the same low affinity as lauric acid (Km, approximately 200 microm). These findings suggest a possible dual role of some PUFAs in activating both UCPn expression and uncoupling activity. UCP2 (UCP3)-dependent H+ translocation activated by all tested FAs was inhibited by purine nucleotides with apparent affinity to UCP2 (reciprocal Ki) decreasing in order: ADP > ATP approximately GTP > GDP >> AMP. Also [3H]GTP ([3H]ATP) binding to isolated Escherichia coli (Kd, approximately 5 microm) or yeast-expressed UCP2 (Kd, approximately 1.5 microm) or UCP3 exhibited high affinity, similar to UCP1. The estimated number of [3H]GTP high affinity (Kd, <0.4 microm) binding sites was (in pmol/mg of protein) 182 in lung mitochondria, 74 in kidney, 28 in skeletal muscle, and approximately 20 in liver mitochondria. We conclude that purine nucleotides must be the physiological inhibitors of UCPn-mediated uncoupling in vivo.
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Affiliation(s)
- Markéta Zackova
- Institute of Physiology, Academy of Sciences of the Czech Republic, Vídenská 1083, 14220 Prague 4, Czech Republic
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25
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Brandalise M, Maia IG, Borecký J, Vercesi AE, Arruda P. Overexpression of plant uncoupling mitochondrial protein in transgenic tobacco increases tolerance to oxidative stress. J Bioenerg Biomembr 2003; 35:203-9. [PMID: 13678271 DOI: 10.1023/a:1024603530043] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
An Arabidopsis thaliana cDNA clone encoding a plant uncoupling mitochondrial protein (AtPUMP1) was overexpressed in transgenic tobacco plants. Analysis of the AtPUMP1 mRNA content in the transgenic lines, determined by Northern blot, revealed variable levels of transgene expression. Antibody probing of Western blots of mitochondrial proteins from three independent transgenic lines showed significant accumulation of AtPUMP1 in this organelle. Overproduction of AtPUMP1 in transgenic tobacco plants led to a significant increase in tolerance to oxidative stress promoted by exogenous hydrogen peroxide as compared to wild-type control plants. These results provide the first biological evidence for a role of PUMP in protection of plant cells against oxidative stress damage.
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Affiliation(s)
- Marcos Brandalise
- Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, C.P. 6010, 13083-970, Campinas, SP, Brazil
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26
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Navet R, Jarmuszkiewicz W, Almeida AM, Sluse-Goffart C, Sluse FE. Energy conservation and dissipation in mitochondria isolated from developing tomato fruit of ethylene-defective mutants failing normal ripening: the effect of ethephon, a chemical precursor of ethylene. J Bioenerg Biomembr 2003; 35:157-68. [PMID: 12887014 DOI: 10.1023/a:1023750204310] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Alternative oxidase (AOX) and uncoupling protein (UCP) are present simultaneously in tomato fruit mitochondria. In a previous work, it has been shown that protein expression and activity of these two energy-dissipating systems exhibit large variations during tomato fruit development and ripening on the vine. It has been suggested that AOX and UCP could be responsible for the respiration increase at the end of ripening and that the cytochrome pathway could be implicated in the climacteric respiratory burst before the onset of ripening. In this study, the use of tomato mutants that fail normal ripening because of deficiencies in ethylene perception or production as well as the treatment of one selected mutant with a chemical precursor of ethylene have revealed that the bioenergetics of tomato fruit development and ripening is under the control of this plant hormone. Indeed, the evolution pattern of bioenergetic features changes with the type of mutation and with the introduction of ethylene into an ethylene-synthesis-deficient tomato fruit mutant during its induced ripening.
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Affiliation(s)
- Rachel Navet
- Laboratory of Bioenergetics, Department of Life Sciences, Institute of Chemistry B6c, University of Liège, Sar-Tilman, B-4000 Liège, Belgium
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27
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Bernardi P, Penzo D, Wojtczak L. Mitochondrial energy dissipation by fatty acids. Mechanisms and implications for cell death. VITAMINS AND HORMONES 2003; 65:97-126. [PMID: 12481544 DOI: 10.1016/s0083-6729(02)65061-7] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
For most cell types, fatty acids are excellent respiratory substrates. After being transported across the outer and inner mitochondrial membranes they undergo beta-oxidation in the matrix and feed electrons into the mitochondrial energy-conserving respiratory chain. On the other hand, fatty acids also physically interact with mitochondrial membranes, and possess the potential to alter their permeability. This occurs according to two mechanisms: an increase in proton conductance of the inner mitochondrial membrane and the opening of the permeability transition pore, an inner membrane high-conductance channel that may be involved in the release of apoptogenic proteins into the cytosol. This article addresses in some detail the mechanisms through which fatty acids exert their protonophoric action and how they modulate the permeability transition pore and discusses the cellular effects of fatty acids, with specific emphasis on their role as potential mitochondrial mediators of apoptotic signaling.
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Affiliation(s)
- Paolo Bernardi
- Department of Biomedical Sciences, Venetian Institute of Molecular Medicine, University of Padova, I-35131 Padova, Italy
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28
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Almeida AM, Navet R, Jarmuszkiewicz W, Vercesi AE, Sluse-Goffart CM, Sluse FE. The energy-conserving and energy-dissipating processes in mitochondria isolated from wild type and nonripening tomato fruits during development on the plant. J Bioenerg Biomembr 2002; 34:487-98. [PMID: 12678440 DOI: 10.1023/a:1022574327117] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Bioenergetics of tomato (Lycopersicon esculentum) development on the plant was followed from the early growing stage to senescence in wild type (climacteric) and nonripening mutant (nor, non-climacteric) fruits. Fruit development was expressed in terms of evolution of chlorophyll a content allowing the assessment of a continuous time-course in both cultivars. Measured parameters: the cytochrome pathway-dependent respiration, i.e., the ATP synthesis-sustained respiration (energy-conserving), the uncoupling protein (UCP) activity-sustained respiration (energy-dissipating), the alternative oxidase(AOX)-mediated respiration (energy-dissipating), as well as the protein expression of UCP and AOX, and free fatty acid content exhibited different evolution patterns in the wild type and nor mutant that can be attributed to their climacteric/nonclimacteric properties, respectively. In the wild type, the climacteric respiratory burst observed in vitro depended totally on an increse in the cytochrome pathway activity sustained by ATP synthesis, while the second respiratory rise during the ripening stage was linked to a strong increase in AOX activity accompanied by an overexpression of AOX protein. In wild type mitochondria, the 10-microM linoleic acid-stimulated UCP-activity-dependent respiration remained constant during the whole fruit development except in senescence where general respiratory decay was observed.
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Affiliation(s)
- Andréa Miyasaka Almeida
- Laboratory of Bioenergetics, Department of Life Sciences, Institute of Chemistry B6, University of Liège, Sart Tilman, B-4000 Liège, Belgium
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29
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Zabrouskov V, Knowles NR. Lipid metabolism during aging of high-alpha-linolenate-phenotype potato tubers. Arch Biochem Biophys 2002; 402:136-48. [PMID: 12051691 DOI: 10.1016/s0003-9861(02)00069-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Previous studies demonstrated that high levels of alpha-linolenate in cell membranes of potato tubers (achieved by overexpressing fatty acid desaturases) enhances lipid peroxidation, oxidative stress, and tuber metabolic rate, effectively accelerating the physiological age of tubers. This study details the changes in lipid molecular species of microsomal and mitochondrial membranes from wild-type (WT) and high-alpha-linolenate tubers during aging. The microsomal and mitochondrial polar lipids of high-alpha-linolenate tubers were dominated by 18:3/18:3 and 16:0/18:3 molecular species. Relative to WT tubers, high-alpha-linolenate tubers had a substantially higher 16:0/18:n to 18:n/18:n molecular species ratio in mitochondria and microsomes, potentially reflecting a compensatory response to maintain membrane biophysical properties in the face of increased unsaturation. Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) accounted for 53 and 37% of polar lipids, respectively, in mitochondria from younger WT and high-alpha-linolenate tubers. The relative proportions of these phospholipids (PL) did not change during aging of WT tubers. In contrast, PE increased to dominate the PL pool of mitochondria during aging of high-alpha-linolenate tubers. While aging effected an increase in mitochondrial 18:3-bearing PCs and PEs in WT tubers, the concentration of 18:3-bearing PCs fell with a concomitant increase in 18:3-bearing PEs during aging of high-alpha-linolenate tubers. These age- and high-alpha-linolenate-induced changes had no effect on the respiration rate and functional integrity of isolated mitochondria. Differential increases in the respiration rates of WT and high-alpha-linolenate tubers during aging were therefore a consequence of unsaturation-dependent alterations in the microenvironments of cells. Microsomal 18:3-bearing PCs, PEs, digalactosyldiacylglycerols (DGDG), and monogalactosyldiacylglycerols all increased in WT tubers during aging. In contrast, a selective loss of 18:3-bearing PCs and DGDGs from microsomes of high-alpha-linolenate tubers likely reflects a greater susceptibility of membranes to peroxidative catabolism during aging. Aging resulted in an increase in sterol/PL ratio in microsomes from WT tubers, due primarily to a decline in PL. In high-alpha-linolenate tubers, the increase in sterol/PL ratio during aging was due to increases in Delta 5-avenasterol and stigmasterol, indicating membrane rigidification and likely contributing to increased membrane permeability. Age-induced changes in 18:3-bearing lipids in membranes of transformed tubers are discussed relative to the development of oxidative stress and accelerated aging.
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Affiliation(s)
- Vladimir Zabrouskov
- Department of Horticulture and Landscape Architecture, Washington State University, P.O. Box 646414, Pullman, WA 99164-6414, USA
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30
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Borecký J, Maia IG, Costa AD, Jezek P, Chaimovich H, de Andrade PB, Vercesi AE, Arruda P. Functional reconstitution of Arabidopsis thaliana plant uncoupling mitochondrial protein (AtPUMP1) expressed in Escherichia coli. FEBS Lett 2001; 505:240-4. [PMID: 11566183 DOI: 10.1016/s0014-5793(01)02835-6] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The Arabidopsis thaliana uncoupling protein (UCP) gene was expressed in Escherichia coli and isolated protein reconstituted into liposomes. Linoleic acid-induced H+ fluxes were sensitive to purine nucleotide inhibition with an apparent K(i) (in mM) of 0.8 (GDP), 0.85 (ATP), 0.98 (GTP), and 1.41 (ADP); the inhibition was pH-dependent. Kinetics of AtPUMP1-mediated H+ fluxes were determined for lauric, myristic, palmitic, oleic, linoleic, and linolenic acids. Properties of recombinant AtPUMP1 indicate that it represents a plant counterpart of animal UCP2 or UCP3. This work brings the functional and genetic approaches together for the first time, providing strong support that AtPUMP1 is truly an UCP.
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Affiliation(s)
- J Borecký
- Department of Membrane Transport Biophysics, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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31
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Jabůrek M, Varecha M, Jezek P, Garlid KD. Alkylsulfonates as probes of uncoupling protein transport mechanism. Ion pair transport demonstrates that direct H(+) translocation by UCP1 is not necessary for uncoupling. J Biol Chem 2001; 276:31897-905. [PMID: 11468281 DOI: 10.1074/jbc.m103507200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mechanism of fatty acid-dependent uncoupling by mitochondrial uncoupling proteins (UCP) is still in debate. We have hypothesized that the anionic fatty acid head group is translocated by UCP, and the proton is transported electroneutrally in the bilayer by flip-flop of the protonated fatty acid. Alkylsulfonates are useful as probes of the UCP transport mechanism. They are analogues of fatty acids, and they are transported by UCP1, UCP2, and UCP3. We show that undecanesulfonate and laurate are mutually competitive inhibitors, supporting the hypothesis that fatty acid anion is transported by UCP1. Alkylsulfonates cannot be protonated because of their low pK(a), consequently, they cannot catalyze electroneutral proton transport in the bilayer and cannot support uncoupling by UCP. We report for the first time that propranolol forms permeant ion pairs with the alkylsulfonates, thereby removing this restriction. Because a proton is transported with the neutral ion pair, the sulfonate is able to deliver protons across the bilayer, behaving as if it were a fatty acid. When ion pair transport is combined with UCP1, we now observe electrophoretic proton transport and uncoupling of brown adipose tissue mitochondria. These experiments confirm that the proton transport of UCP-mediated uncoupling takes place in the lipid bilayer and not via UCP itself. Thus, UCP1, like other members of its gene family, translocates anions and does not translocate protons.
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Affiliation(s)
- M Jabůrek
- Department of Biochemistry and Molecular Biology, Oregon Graduate Institute of Science and Technology, Portland, Oregon 97006, USA
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32
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Considine MJ, Daley DO, Whelan J. The expression of alternative oxidase and uncoupling protein during fruit ripening in mango. PLANT PHYSIOLOGY 2001; 126:1619-29. [PMID: 11500560 PMCID: PMC117161 DOI: 10.1104/pp.126.4.1619] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2001] [Accepted: 05/07/2001] [Indexed: 05/19/2023]
Abstract
The expression of alternative oxidase (Aox) and uncoupling proteins (Ucp) was investigated during ripening in mango (Mangifera indica) and compared with the expression of peroxisomal thiolase, a previously described ripening marker in mango. The multigene family for the Aox in mango was expressed differentially during ripening. Abundance of Aox message and protein both peaked at the ripe stage. Expression of the single gene for the Ucp peaked at the turning stage and the protein abundance peaked at the ripe stage. Proteins of the cytochrome chain peaked at the mature stage of ripening. The pattern of protein accumulation suggested that increases in cytochrome chain components played an important role in facilitating the climacteric burst of respiration and that the Aox and Ucp may play a role in post-climacteric senescent processes. Because both message and protein for the Aox and Ucp increased in a similar pattern, it suggests that their expression is not controlled in a reciprocal manner but may be active simultaneously.
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Affiliation(s)
- M J Considine
- Department of Biochemistry, The University of Western Australia, Nedlands, Western Australia 6907, Australia
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33
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Hanák P, Jezek P. Mitochondrial uncoupling proteins and phylogenesis--UCP4 as the ancestral uncoupling protein. FEBS Lett 2001; 495:137-41. [PMID: 11334880 DOI: 10.1016/s0014-5793(01)02338-9] [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: 11/18/2022]
Abstract
We searched for the previously defined uncoupling protein (UCP) signatures [Jezek, P. and Urbánková, E. (2000) IUBMB Life 49, 63-70] in genomes of Drosophila melanogaster, Caenorhabditis elegans, Dictyostelium discoideum, and Arabidopsis thaliana. We identified four UCPs in Drosophila and one in Caenorhabditis or Dictyostelium as close relatives of human UCP4 (BMCP), but distant from UCP1, UCP2, UCP3, and two plant UCPs of Arabidopsis. But the third Arabidopsis UCP is the closest UCP4 relative. This suggests that UCP4 represents the ancestral UCP from which other mammalian and plant UCPs diverged. Speculations on UCP4 participation in apoptosis are thus supported by its early phylogenetic occurrence.
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Affiliation(s)
- P Hanák
- Department of Membrane Transport Biophysics, No.375, Institute of Physiology, Academy of Sciences of the Czech Republic, Vídenská 1083, CZ 14220, Prague, Czech Republic
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34
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Affourtit C, Krab K, Moore AL. Control of plant mitochondrial respiration. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1504:58-69. [PMID: 11239485 DOI: 10.1016/s0005-2728(00)00239-5] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Plant mitochondria are characterised by the presence of both phosphorylating (cytochrome) and non-phosphorylating (alternative) respiratory pathways, the relative activities of which directly affect the efficiency of mitochondrial energy conservation. Different approaches to study the regulation of the partitioning of reducing equivalents between these routes are critically reviewed. Furthermore, an updated view is provided regarding the understanding of plant mitochondrial respiration in terms of metabolic control. We emphasise the extent to which kinetic modelling and 'top-down' metabolic control analysis improve the insight in phenomena related to plant mitochondrial respiration. This is illustrated with an example regarding the affinity of the plant alternative oxidase for oxygen.
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Affiliation(s)
- C Affourtit
- Department of Biochemistry, University of Sussex, Falmer, Brighton, UK.
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Engstová H, Zácková M, Růzicka M, Meinhardt A, Hanus J, Krämer R, Jezek P. Natural and azido fatty acids inhibit phosphate transport and activate fatty acid anion uniport mediated by the mitochondrial phosphate carrier. J Biol Chem 2001; 276:4683-91. [PMID: 11085992 DOI: 10.1074/jbc.m009409200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The electroneutral P(i) uptake via the phosphate carrier (PIC) in rat liver and heart mitochondria is inhibited by fatty acids (FAs), by 12-(4-azido-2-nitrophenylamino)dodecanoic acid (AzDA) and heptylbenzoic acid ( approximately 1 microm doses) and by lauric, palmitic, or 12-azidododecanoic acids ( approximately 0.1 mm doses). In turn, reconstituted E. coli-expressed yeast PIC mediated anionic FA uniport with a similar pattern leading to FA cycling and H(+) uniport. The kinetics of P(i)/P(i) exchange on recombinant PIC in the presence of AzDA better corresponded to a competitive inhibition mechanism. Methanephosphonate was identified as a new PIC substrate. Decanephosphonate, butanephosphonate, 4-nitrophenylphosphate, and other P(i) analogs were not translocated and did not inhibit P(i) transport. However, methylenediphosphonate and iminodi(methylenephosphonate) inhibited both electroneutral P(i) uptake and FA cycling via PIC. AzDA analog 16-(4-azido-2-nitrophenylamino)-[(3)H(4)]-hexadecanoic acid ((3)H-AzHA) bound upon photoactivation to several mitochondrial proteins, including the 30- and 34-kDa bands. The latter was ascribed to PIC due to its specific elution pattern on Blue Sepharose and Affi-Gel. (3)H-AzHA photolabeling of recombinant PIC was prevented by methanephosphonate and diphosphonates and after premodification with 4-azido-2-nitrophenylphosphate. Hence, the demonstrated PIC interaction with monovalent long-chain FA anions, but with divalent phosphonates of short chain only, indicates a pattern distinct from that valid for the mitochondrial uncoupling protein-1.
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Affiliation(s)
- H Engstová
- Institute of Physiology, Department of Membrane Transport Biophysics, Academy of Sciences of the Czech Republic, Prague CZ 14220, Czech Republic
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36
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Jezek P, Costa AD, Vercesi AE. Important amino acid residues of potato plant uncoupling protein (StUCP). Braz J Med Biol Res 2000; 33:1413-20. [PMID: 11105092 DOI: 10.1590/s0100-879x2000001200003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chemical modifications were used to identify some of the functionally important amino acid residues of the potato plant uncoupling protein (StUCP). The proton-dependent swelling of potato mitochondria in K(+)-acetate in the presence of linoleic acid and valinomycin was inhibited by mersalyl (K(i) = 5 microM) and other hydrophilic SH reagents such as Thiolyte MB, iodoacetate and 5, 5'-dithio-bis-(2-nitrobenzoate), but not by hydrophobic N-ethylmaleimide. This pattern of inhibition by SH reagents was similar to that of brown adipose tissue uncoupling protein (UCP1). As with UCP1, the arginine reagent 2,3-butadione, but not N-ethylmaleimide or other hydrophobic SH reagents, prevented the inhibition of StUCP-mediated transport by ATP in isolated potato mitochondria or with reconstituted StUCP. The results indicate that the most reactive amino acid residues in UCP1 and StUCP are similar, with the exception of N-ethylmaleimide-reactive cysteines in the purine nucleotide-binding site.
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Affiliation(s)
- P Jezek
- Department of Membrane Transport Biophysics, Institute of Physiology, Academy of Science, Prague, Czech Republic
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37
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Garlid KD, Jabůrek M, Jezek P, Varecha M. How do uncoupling proteins uncouple? BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1459:383-9. [PMID: 11004454 DOI: 10.1016/s0005-2728(00)00175-4] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
According to the proton buffering model, introduced by Klingenberg, UCP1 conducts protons through a hydrophilic pathway lined with fatty acid head groups that buffer the protons as they move across the membrane. According to the fatty acid protonophore model, introduced by Garlid, UCPs do not conduct protons at all. Rather, like all members of this gene family, they are anion carriers. A variety of anions are transported, but the physiological substrates are fatty acid (FA) anions. Because the carboxylate head group is translocated by UCP, and because the protonated FA rapidly diffuses across the membrane, this mechanism permits FA to behave as regulated cycling protonophores. Favoring the latter mechanism is the fact that the head group of long-chain alkylsulfonates, strong acid analogues of FA, is also translocated by UCP.
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Affiliation(s)
- K D Garlid
- Department of Biochemistry and Molecular Biology, Oregon Graduate Institute of Science and Technology, Beaverton 97006, USA.
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38
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Screening of mitochondrial proteins in winter rye, winter wheat, elymus and maize with an immunochemical affinity to the stress protein 310 kD and their intramitochondrial localization in winter wheat. J Therm Biol 2000. [DOI: 10.1016/s0306-4565(99)00030-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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39
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Casolo V, Braidot E, Chiandussi E, Macrì F, Vianello A. The role of mild uncoupling and non-coupled respiration in the regulation of hydrogen peroxide generation by plant mitochondria. FEBS Lett 2000; 474:53-7. [PMID: 10828450 DOI: 10.1016/s0014-5793(00)01576-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The roles of mild uncoupling caused by free fatty acids (mediated by plant uncoupling mitochondrial protein (PUMP) and ATP/ADP carrier (AAC)) and non-coupled respiration (alternative oxidase (AO)) on H(2)O(2) formation by plant mitochondria were examined. Both laurate and oleate prevent H(2)O(2) formation dependent on the oxidation of succinate. Conversely, these free fatty acids (FFA) only slightly affect that dependent on malate plus glutamate oxidation. Carboxyatractylate (CAtr), an inhibitor of AAC, completely inhibits oleate- or laurate-stimulated oxygen consumption linked to succinate oxidation, while GDP, an inhibitor of PUMP, caused only a 30% inhibition. In agreement, CAtr completely restores the oleate-inhibited H(2)O(2) formation, while GDP induces only a 30% restoration. Both oleate and laurate cause a mild uncoupling of the electrical potential (generated by succinate), which is then followed by a complete collapse with a sigmoidal kinetic. FFA also inhibit the succinate-dependent reverse electron transfer. Diamide, an inhibitor of AO, favors the malate plus glutamate-dependent H(2)O(2) formation, while pyruvate (a stimulator of AO) inhibits it. These results show that the succinate-dependent H(2)O(2) formation occurs at the level of Complex I by a reverse electron transport. This generation appears to be prevented by mild uncoupling mediated by FFA. The anionic form of FFA appears to be shuttled by AAC rather than PUMP. The malate plus glutamate-dependent H(2)O(2) formation is, conversely, mainly prevented by non-coupled respiration (AO).
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Affiliation(s)
- V Casolo
- Department of Biology and Agro-Industrial Economics, Section of Plant Biology, University of Udine, via Cotonificio 108, I-33100, Udine, Italy
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40
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Jarmuszkiewicz W, Almeida AM, Vercesi AE, Sluse FE, Sluse-Goffart CM. Proton re-uptake partitioning between uncoupling protein and ATP synthase during benzohydroxamic acid-resistant state 3 respiration in tomato fruit mitochondria. J Biol Chem 2000; 275:13315-20. [PMID: 10788438 DOI: 10.1074/jbc.275.18.13315] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The yield of oxidative phosphorylation in isolated tomato fruit mitochondria depleted of free fatty acids remains constant when respiratory rates are decreased by a factor of 3 by the addition of n-butyl malonate. This constancy makes the determination of the contribution of the linoleic acid-induced energy-dissipating pathway by the ADP/O method possible. No decrease in membrane potential is observed in state 3 respiration with increasing concentration of n-butyl malonate, indicating that the rate of ATP synthesis is steeply dependent on membrane potential. Linoleic acid decreases the yield of oxidative phosphorylation in a concentration-dependent manner by a pure protonophoric process like that in the presence of FCCP. ADP/O measurements allow calculation of the part of respiration leading to ATP synthesis and the part of respiration sustained by the dissipative H(+) re-uptake induced by linoleic acid. Respiration sustained by this energy-dissipating process remains constant at a given LA concentration until more than 50% inhibition of state 3 respiration by n-butyl malonate is achieved. The energy dissipative contribution to oxygen consumption is proposed to be equal to the protonophoric activity of plant uncoupling protein divided by the intrinsic H(+)/O of the cytochrome pathway. It increases with linoleic acid concentration, taking place at the expense of ADP phosphorylation without an increase in the respiration.
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Affiliation(s)
- W Jarmuszkiewicz
- Departamento de Patologia Clinica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, 13083-970 Campinas SP, Brazil
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41
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Zácková M, Krämer R, Jezek P. Interaction of mitochondrial phosphate carrier with fatty acids and hydrophobic phosphate analogs. Int J Biochem Cell Biol 2000; 32:499-508. [PMID: 10736565 DOI: 10.1016/s1357-2725(00)00006-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Mitochondrial transporters, in particular uncoupling proteins and the ADP/ATP carrier, are known to mediate uniport of anionic fatty acids (FAs), allowing FA cycling which is completed by the passive movement of FAs across the membrane in their protonated form. This study investigated the ability of the mitochondrial phosphate carrier to catalyze such a mechanism and, furthermore, how this putative activity is related to the previously observed HgCl(2)-induced uniport mode. The yeast mitochondrial phosphate carrier was expressed in Escherichia coli and then reconstituted into lipid vesicles. The FA-induced H(+) uniport or Cl(-) uniport were monitored fluorometrically after HgCl(2) addition. These transport activities were further characterized by testing various inhibitors of the two different transport modes. The phosphate carrier was found to mediate FA cycling, which led to H(+) efflux in proteoliposomes. This activity was insensitive to ATP, mersalyl or N-ethylmaleimide and was inhibited by methylenediphosphonate and iminodi(methylenephosphonate), which are new inhibitors of mitochondrial phosphate transport. Also, the HgCl(2) induced Cl(-) uniport mediated by the reconstituted yeast PIC, was found to be inhibited by these reagents. Both methylenediphosphonate and iminodi(methylenephosphonate) blocked unidirectional Cl(-) uptake, whereas Cl(-) efflux was inhibited by iminodi(methylenephosphonate) and phosphonoformic acid only. These results suggest that a hydrophobic domain, interacting with FAs, exists in the mitochondrial phosphate carrier, which is distinct from the phosphate transport pathway. This domain allows for FA anion uniport via the phosphate carrier and consequently, FA cycling that should lead to uncoupling in mitochondria. This might be considered as a side function of this carrier.
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Affiliation(s)
- M Zácková
- Institute of Physiology, Department of Membrane Transport Biophysics, Academy of Sciences of the Czech Republic, Vídenská 1083, 14220, Prague 4, Czech Republic
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42
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Pastore D, Fratianni A, Di Pede S, Passarella S. Effects of fatty acids, nucleotides and reactive oxygen species on durum wheat mitochondria. FEBS Lett 2000; 470:88-92. [PMID: 10722851 DOI: 10.1016/s0014-5793(00)01292-8] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Linoleic acid (LA) and other fatty acids added to respiring durum wheat mitochondria (DWM) were found to cause a remarkable membrane potential (deltaPsi) decrease, as monitored by measuring safranin fluorescence. The rate of deltaPsi decrease showed (i) saturation dependence on LA concentration; (ii) fatty acid specificity; (iii) inhibition by externally added ATP, GDP, GTP and Mg(2+) and (iv) sigmoid dependence upon initial DeltaPsi, thus suggesting the existence of an active plant mitochondrial uncoupling protein (PUMP) in mitochondria from monocotyledonous species (durum wheat, Triticum durum Desf.). Surprisingly, the rate of the linoleate dependent DeltaPsi decrease was found to be activated by reactive oxygen species (ROS) (hydrogen peroxide and superoxide anion) and, moreover, linoleate proved to lower the mitochondrial generation of superoxide anion. These results suggest that ROS can activate PUMP, thus protecting the cell against mitochondrial ROS production.
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Affiliation(s)
- D Pastore
- Dipartimento di Scienze Animali, Vegetali e dell'Ambiente, Università del Molise, Via De Sanctis, 86100, Campobasso, Italy
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43
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Sluse FE, Jarmuszkiewicz W. Activity and functional interaction of alternative oxidase and uncoupling protein in mitochondria from tomato fruit. Braz J Med Biol Res 2000; 33:259-68. [PMID: 10719376 DOI: 10.1590/s0100-879x2000000300002] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cyanide-resistant alternative oxidase (AOX) is not limited to plant mitochondria and is widespread among several types of protists. The uncoupling protein (UCP) is much more widespread than previously believed, not only in tissues of higher animals but also in plants and in an amoeboid protozoan. The redox energy-dissipating pathway (AOX) and the proton electrochemical gradient energy-dissipating pathway (UCP) lead to the same final effect, i.e., a decrease in ATP synthesis and an increase in heat production. Studies with green tomato fruit mitochondria show that both proteins are present simultaneously in the membrane. This raises the question of a specific physiological role for each energy-dissipating system and of a possible functional connection between them (shared regulation). Linoleic acid, an abundant free fatty acid in plants which activates UCP, strongly inhibits cyanide-resistant respiration mediated by AOX. Moreover, studies of the evolution of AOX and UCP protein expression and of their activities during post-harvest ripening of tomato fruit show that AOX and plant UCP work sequentially: AOX activity decreases in early post-growing stages and UCP activity is decreased in late ripening stages. Electron partitioning between the alternative oxidase and the cytochrome pathway as well as H+ gradient partitioning between ATP synthase and UCP can be evaluated by the ADP/O method. This method facilitates description of the kinetics of energy-dissipating pathways and of ATP synthase when state 3 respiration is decreased by limitation of oxidizable substrate.
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Affiliation(s)
- F E Sluse
- Laboratory of Bioenergetics, Centre of Oxygen, Research, Development, Institute of Chemistry B6, University of Liege, Liege, Belgium.
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44
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Kowaltowski AJ. Alternative mitochondrial functions in cell physiopathology: beyond ATP production. Braz J Med Biol Res 2000; 33:241-50. [PMID: 10657067 DOI: 10.1590/s0100-879x2000000200014] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
It is well known that mitochondria are the main site for ATP generation within most tissues. However, mitochondria also participate in a surprising number of alternative activities, including intracellular Ca2+ regulation, thermogenesis and the control of apoptosis. In addition, mitochondria are the main cellular generators of reactive oxygen species, and may trigger necrotic cell death under conditions of oxidative stress. This review concentrates on these alternative mitochondrial functions, and their role in cell physiopathology.
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Affiliation(s)
- A J Kowaltowski
- Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, SP, Brasil.
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45
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Nantes IL, Fagian MM, Catisti R, Arruda P, Maia IG, Vercesi AE. Low temperature and aging-promoted expression of PUMP in potato tuber mitochondria. FEBS Lett 1999; 457:103-6. [PMID: 10486573 DOI: 10.1016/s0014-5793(99)01017-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In this communication, we show that the plant uncoupling mitochondrial protein (PUMP) present in potato tuber mitochondria is induced by aging at 28 degrees C and that this induction is strongly stimulated when the potato tubers are stored at low temperature (4 degrees C). PUMP activity was detected by the degree of linoleic acid (LA)-induced ATP-sensitive mitochondrial uncoupling measured as a function of the decrease in membrane potential (delta psi). The PUMP content was evaluated by immunoblot analysis using polyclonal antibodies raised against potato PUMP that specifically detected a 32 kDa band. In agreement with the effect of LA on delta psi, the content of the 32 kDa band increased during storage and was stimulated by low temperature. These results support the proposed role of PUMP in plant thermogenesis and possibly in fruit ripening and senescence.
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Affiliation(s)
- I L Nantes
- Departamento de Patologia Clínica, NMCE, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, SP, Brazil
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46
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Jarmuszkiewicz W, Sluse-Goffart CM, Hryniewiecka L, Sluse FE. Identification and characterization of a protozoan uncoupling protein in Acanthamoeba castellanii. J Biol Chem 1999; 274:23198-202. [PMID: 10438491 DOI: 10.1074/jbc.274.33.23198] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
An uncoupling protein (UCP) has been identified in mitochondria from Acanthamoeba castellanii, a nonphotosynthetic soil amoeboid protozoon that, in molecular phylogenesis, appears on a branch basal to the divergence points of plants, animals, and fungi. The existence of UCP in A. castellanii (AcUCP) has been revealed using antibodies raised against plant UCP. Its molecular mass (32,000 Da) was similar to those of plant and mammalian UCPs. The activity of AcUCP has been investigated in mitochondria depleted of free fatty acids. Additions of linoleic acid stimulated state 4 respiration and decreased transmembrane electrical potential (DeltaPsi) in a manner expected from fatty acid cycling-linked H(+) reuptake. The half-maximal stimulation by linoleic acid was reached at 8.1 +/- 0.4 microM. Bovine serum albumin (fatty acid-free), which adsorbs linoleic acid, reversed the respiratory stimulation and correspondingly restored DeltaPsi. AcUCP was only weakly inhibited by purine nucleotides like UCP in plants. A single force-flow relationship has been observed for state 4 respiration with increasing concentration of linoleic acid or of an uncoupler and for state 3 respiration with increasing concentration of oligomycin, indicating that linoleic acid has a pure protonophoric effect. The activity of AcUCP in state 3 has been evidenced by ADP/oxygen atom determination. The discovery of AcUCP indicates that UCPs emerged, as specialized proteins for H(+) cycling, early during phylogenesis before the major radiation of phenotypic diversity in eukaryotes and could occur in the whole eukaryotic world.
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Affiliation(s)
- W Jarmuszkiewicz
- Department of Bioenergetics, Adam Mickiewicz University, Fredry 10, 61-701 Poznan, Poland.
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47
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Almeida AM, Jarmuszkiewicz W, Khomsi H, Arruda P, Vercesi AE, Sluse FE. Cyanide-resistant, ATP-synthesis-sustained, and uncoupling-protein-sustained respiration during postharvest ripening of tomato fruit. PLANT PHYSIOLOGY 1999; 119:1323-30. [PMID: 10198091 PMCID: PMC32017 DOI: 10.1104/pp.119.4.1323] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/1998] [Accepted: 12/21/1998] [Indexed: 05/20/2023]
Abstract
Tomato (Lycopersicon esculentum) mitochondria contain both alternative oxidase (AOX) and uncoupling protein as energy-dissipating systems that can decrease the efficiency of oxidative phosphorylation. We followed the cyanide (CN)-resistant, ATP-synthesis-sustained, and uncoupling-protein-sustained respiration of isolated mitochondria, as well as the immunologically detectable levels of uncoupling protein and AOX, during tomato fruit ripening from the mature green stage to the red stage. The AOX protein level and CN-resistant respiration of isolated mitochondria decreased with ripening from the green to the red stage. The ATP-synthesis-sustained respiration followed the same behavior. In contrast, the level of uncoupling protein and the total uncoupling-protein-sustained respiration of isolated mitochondria decreased from only the yellow stage on. We observed an acute inhibition of the CN-resistant respiration by linoleic acid in the micromolar range. These results suggest that the two energy-dissipating systems could have different roles during the ripening process.
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Affiliation(s)
- AM Almeida
- Departamento de Patologia Clinica, Faculdade de Cieancias Medicas (A.M.A., A.E.V.)
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48
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Jarmuszkiewicz W, Almeida AM, Sluse-Goffart CM, Sluse FE, Vercesi AE. Linoleic acid-induced activity of plant uncoupling mitochondrial protein in purified tomato fruit mitochondria during resting, phosphorylating, and progressively uncoupled respiration. J Biol Chem 1998; 273:34882-6. [PMID: 9857016 DOI: 10.1074/jbc.273.52.34882] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
An uncoupling protein was recently discovered in plant mitochondria and demonstrated to function similarly to the uncoupling protein of brown adipose tissue. In this work, green tomato fruit mitochondria were purified on a self-generating Percoll gradient in the presence of 0.5% bovine serum albumin to deplete mitochondria of endogenous free fatty acids. The uncoupling protein activity was induced by the addition of linoleic acid during the resting state, and in the progressively uncoupled state, as well as during phosphorylating respiration in the presence of benzohydroxamic acid, an inhibitor of the alternative oxidase and with succinate (+ rotenone) as oxidizable substrate. Linoleic acid strongly stimulated the resting respiration in fatty acid-depleted mitochondria but had no effect on phosphorylating respiration, suggesting no activity of the uncoupling protein in this respiratory state. Progressive uncoupling of state 4 respiration decreased the stimulation by linoleic acid. The similar respiratory rates in phosphorylating and fully uncoupled respiration in the presence and absence of linoleic acid suggested that a rate-limiting step on the dehydrogenase side of the respiratory chain was responsible for the insensitivity of phosphorylating respiration to linoleic acid. Indeed, the ADP/O ratio determined by ADP/O pulse method was decreased by linoleic acid, indicating that uncoupling protein was active during phosphorylating respiration and was able to divert energy from oxidative phosphorylation. Moreover, the respiration rates appeared to be determined by membrane potential independently of the presence of linoleic acid, indicating that linoleic acid-induced stimulation of respiration is due to a pure protonophoric activity without any direct effect on the electron transport chain.
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Affiliation(s)
- W Jarmuszkiewicz
- Department of Bioenergetics, Adam Mickiewicz University, Fredry 10, 61-701 Poznan, Poland
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49
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Maia IG, Benedetti CE, Leite A, Turcinelli SR, Vercesi AE, Arruda P. AtPUMP: an Arabidopsis gene encoding a plant uncoupling mitochondrial protein. FEBS Lett 1998; 429:403-6. [PMID: 9662458 DOI: 10.1016/s0014-5793(98)00634-6] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A cDNA clone (AtPUMP) encoding a plant uncoupling mitochondrial protein was isolated from Arabidopsis thaliana. The cDNA contains an open reading frame of 921 nucleotides encoding 306 amino acids (predicted molecular weight 32,708). The predicted polypeptide is 81% identical and 89% similar to the potato UCP-like protein, and includes an energy transfer protein motif common to mitochondrial transporters. The AtPUMP gene exists as a single copy in the Arabidopsis genome. The corresponding transcript was expressed in all tissues and was strongly induced by cold treatment. We suggest that the putative AtPUMP protein may play a role in heat-requiring physiological events in Arabidopsis.
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Affiliation(s)
- I G Maia
- Centro de Biologia Molecular e Engenharia Genética, C.P. 6109, Universidade Estadual de Campinas, SP, Brazil
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50
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Jezek P, Engstová H, Zácková M, Vercesi AE, Costa AD, Arruda P, Garlid KD. Fatty acid cycling mechanism and mitochondrial uncoupling proteins. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1365:319-27. [PMID: 9693744 DOI: 10.1016/s0005-2728(98)00084-x] [Citation(s) in RCA: 144] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We hypothesize that fatty acid-induced uncoupling serves in bioenergetic systems to set the optimum efficiency and tune the degree of coupling of oxidative phosphorylation. Uncoupling results from fatty acid cycling, enabled by several phylogenetically specialized proteins and, to a lesser extent, by other mitochondrial carriers. It is suggested that the regulated uncoupling in mammalian mitochondria is provided by uncoupling proteins UCP-1, UCP-2 and UCP-3, whereas in plant mitochondria by PUMP and StUCP, all belonging to the gene family of mitochondrial carriers. UCP-1, and hypothetically UCP-3, serve mostly to provide nonshivering thermogenesis in brown adipose tissue and skeletal muscle, respectively. Fatty acid cycling was documented for UCP-1, PUMP and ADP/ATP carrier, and is predicted also for UCP-2 and UCP-3. UCP-1 mediates a purine nucleotide-sensitive uniport of monovalent unipolar anions, including anionic fatty acids. The return of protonated fatty acid leads to H+ uniport and uncoupling. UCP-2 is probably involved in the regulation of body weight and energy balance, in fever, and defense against generation of reactive oxygen species. PUMP has been discovered in potato tubers and immunologically detected in fruits and corn, whereas StUCP has been cloned and sequenced froma a potato gene library. PUMP is supposed to act in the termination of synthetic processes in mature fruits and during the climacteric respiratory rise.
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Affiliation(s)
- P Jezek
- Department of Membrane Transport Biophysics, Academy of Sciences of the Czech Republic, Prague.
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