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Sargsyan Y, Kalinowski J, Thoms S. Calcium in peroxisomes: An essential messenger in an essential cell organelle. Front Cell Dev Biol 2022; 10:992235. [PMID: 36111338 PMCID: PMC9468670 DOI: 10.3389/fcell.2022.992235] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 08/10/2022] [Indexed: 11/17/2022] Open
Abstract
Calcium is a central signal transduction element in biology. Peroxisomes are essential cellular organelles, yet calcium handling in peroxisomes has been contentious. Recent advances show that peroxisomes are part of calcium homeostasis in cardiac myocytes and therefore may contribute to or even shape their calcium-dependent functionality. However, the mechanisms of calcium movement between peroxisomes and other cellular sites and their mediators remain elusive. Here, we review calcium handling in peroxisomes in concert with other organelles and summarize the most recent knowledge on peroxisomal involvement in calcium dynamics with a focus on mammalian cells.
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Affiliation(s)
- Yelena Sargsyan
- Department for Biochemistry and Molecular Medicine, Medical School EWL, Bielefeld University, Bielefeld, Germany
- Department of Child and Adolescent Health, University Medical Center, Göttingen, Germany
| | - Julia Kalinowski
- Department for Biochemistry and Molecular Medicine, Medical School EWL, Bielefeld University, Bielefeld, Germany
| | - Sven Thoms
- Department for Biochemistry and Molecular Medicine, Medical School EWL, Bielefeld University, Bielefeld, Germany
- Department of Child and Adolescent Health, University Medical Center, Göttingen, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Göttingen, Göttingen, Germany
- *Correspondence: Sven Thoms,
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Van Veldhoven PP, de Schryver E, Young SG, Zwijsen A, Fransen M, Espeel M, Baes M, Van Ael E. Slc25a17 Gene Trapped Mice: PMP34 Plays a Role in the Peroxisomal Degradation of Phytanic and Pristanic Acid. Front Cell Dev Biol 2020; 8:144. [PMID: 32266253 PMCID: PMC7106852 DOI: 10.3389/fcell.2020.00144] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 02/20/2020] [Indexed: 12/04/2022] Open
Abstract
Mice lacking PMP34, a peroxisomal membrane transporter encoded by Slc25a17, did not manifest any obvious phenotype on a Swiss Webster genetic background, even with various treatments designed to unmask impaired peroxisomal functioning. Peroxisomal α- and β-oxidation rates in PMP34 deficient fibroblasts or liver slices were not or only modestly affected and in bile, no abnormal bile acid intermediates were detected. Peroxisomal content of cofactors like CoA, ATP, NAD+, thiamine-pyrophosphate and pyridoxal-phosphate, based on direct or indirect data, appeared normal as were tissue plasmalogen and very long chain fatty acid levels. However, upon dietary phytol administration, the knockout mice displayed hepatomegaly, liver inflammation, and an induction of peroxisomal enzymes. This phenotype was partially mediated by PPARα. Hepatic triacylglycerols and cholesterylesters were elevated and both phytanic acid and pristanic acid accumulated in the liver lipids, in females to higher extent than in males. In addition, pristanic acid degradation products were detected, as wells as the CoA-esters of all these branched fatty acids. Hence, PMP34 is important for the degradation of phytanic/pristanic acid and/or export of their metabolites. Whether this is caused by a shortage of peroxisomal CoA affecting the intraperoxisomal formation of pristanoyl-CoA (and perhaps of phytanoyl-CoA), or the SCPx-catalyzed thiolytic cleavage during pristanic acid β-oxidation, could not be proven in this model, but the phytol-derived acyl-CoA profile is compatible with the latter possibility. On the other hand, the normal functioning of other peroxisomal pathways, and especially bile acid formation, seems to exclude severe transport problems or a shortage of CoA, and other cofactors like FAD, NAD(P)+, TPP. Based on our findings, PMP34 deficiency in humans is unlikely to be a life threatening condition but could cause elevated phytanic/pristanic acid levels in older adults.
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Affiliation(s)
| | - Evelyn de Schryver
- LIPIT, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Stephen G. Young
- Departments of Medicine and Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - An Zwijsen
- Laboratory of Developmental Signaling, Department Human Genetics, VIB-KU Leuven, Leuven, Belgium
| | - Marc Fransen
- LIPIT, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Marc Espeel
- Department of Anatomy, Embryology, Histology and Medical Physics, Ghent University, Ghent, Belgium
| | - Myriam Baes
- Laboratory of Cell Metabolism, Faculty of Pharmaceutical Sciences, KU Leuven, Leuven, Belgium
| | - Elke Van Ael
- LIPIT, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
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Kitta R, Yamahama Y, Yamamoto T, Mase K, Sawada H. Molecular Characterization and Tissue Distribution of Mitochondrial Ca2+-Dependent Solute Carrier Protein during Prevention of Diapause by HCl Treatment in the Silkworm,Bombyx mori. Zoolog Sci 2018; 35:487-493. [DOI: 10.2108/zs180041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Ryo Kitta
- Department of Biosciences, College of Humanities and Sciences, Nihon University, Sakurajosui 3-25-40, Setagaya-ku, Tokyo 156-8550, Japan
| | - Yumi Yamahama
- Department of Biology, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
| | - Takayuki Yamamoto
- Division of Biology, College of Liberal Arts and Sciences, Kitasato University, Sagamihara, Kanagawa 228-8555, Japan
| | - Keisuke Mase
- Department of Biosciences, College of Humanities and Sciences, Nihon University, Sakurajosui 3-25-40, Setagaya-ku, Tokyo 156-8550, Japan
| | - Hiroshi Sawada
- Department of Biosciences, College of Humanities and Sciences, Nihon University, Sakurajosui 3-25-40, Setagaya-ku, Tokyo 156-8550, Japan
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Zara V, Ferramosca A, Günnewig K, Kreimendahl S, Schwichtenberg J, Sträter D, Çakar M, Emmrich K, Guidato P, Palmieri F, Rassow J. Mimivirus-Encoded Nucleotide Translocator VMC1 Targets the Mitochondrial Inner Membrane. J Mol Biol 2018; 430:5233-5245. [PMID: 30261167 DOI: 10.1016/j.jmb.2018.09.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 09/18/2018] [Accepted: 09/18/2018] [Indexed: 01/08/2023]
Abstract
Mimivirus (Acanthamoeba polyphaga mimivirus) was the first giant DNA virus identified in an amoeba species. Its genome contains at least 979 genes. One of these, L276, encodes a nucleotide translocator with similarities to mitochondrial metabolite carriers, provisionally named viral mitochondrial carrier 1 (VMC1). In this study, we investigated the intracellular distribution of VMC1 upon expression in HeLa cells and in the yeast Saccharomyces cerevisiae. We found that VMC1 is specifically targeted to mitochondria and to the inner mitochondrial membrane. Newly synthesized VMC1 binds to the mitochondrial outer-membrane protein Tom70 and translocates through the import channel formed by the β-barrel protein Tom40. Derivatization of the four cysteine residues inside Tom40 by N-ethylmaleimide caused a delay in translocation but not a complete occlusion. Cell viability was not reduced by VMC1. Neither the mitochondrial membrane potential nor the intracellular production of reactive oxygen species was affected. Similar to endogenous metabolite carriers, mimivirus-encoded VMC1 appears to act as a specific translocator in the mitochondrial inner membrane. Due to its permeability for deoxyribonucleotides, VMC1 confers to the mitochondria an opportunity to contribute nucleotides for the replication of the large DNA genome of the virus.
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Affiliation(s)
- Vincenzo Zara
- Department of Environmental and Biological Sciences and Technologies, University of Salento, 73100 Lecce, Italy
| | - Alessandra Ferramosca
- Department of Environmental and Biological Sciences and Technologies, University of Salento, 73100 Lecce, Italy
| | - Kathrin Günnewig
- Institute of Biochemistry and Pathobiochemistry, Ruhr-University Bochum, 44780 Bochum, Germany
| | - Sebastian Kreimendahl
- Institute of Biochemistry and Pathobiochemistry, Ruhr-University Bochum, 44780 Bochum, Germany
| | - Jan Schwichtenberg
- Institute of Biochemistry and Pathobiochemistry, Ruhr-University Bochum, 44780 Bochum, Germany
| | - Dina Sträter
- Institute of Biochemistry and Pathobiochemistry, Ruhr-University Bochum, 44780 Bochum, Germany
| | - Mahmut Çakar
- Institute of Biochemistry and Pathobiochemistry, Ruhr-University Bochum, 44780 Bochum, Germany
| | - Kerstin Emmrich
- Institute of Biochemistry and Pathobiochemistry, Ruhr-University Bochum, 44780 Bochum, Germany
| | - Patrick Guidato
- Institute of Biochemistry and Pathobiochemistry, Ruhr-University Bochum, 44780 Bochum, Germany
| | - Ferdinando Palmieri
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70125 Bari, Italy
| | - Joachim Rassow
- Institute of Biochemistry and Pathobiochemistry, Ruhr-University Bochum, 44780 Bochum, Germany.
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Del Arco A, Contreras L, Pardo B, Satrustegui J. Calcium regulation of mitochondrial carriers. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:2413-21. [PMID: 27033520 DOI: 10.1016/j.bbamcr.2016.03.024] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 03/23/2016] [Accepted: 03/23/2016] [Indexed: 11/16/2022]
Abstract
Mitochondrial function is regulated by calcium. In addition to the long known effects of matrix Ca(2+), regulation of metabolite transport by extramitochondrial Ca(2+) represents an alternative Ca(2+)-dependent mechanism to regulate mitochondrial function. The Ca(2+) regulated mitochondrial transporters (CaMCs) are well suited for that role, as they contain long N-terminal extensions harboring EF-hand Ca(2+) binding domains facing the intermembrane space. They fall in two groups, the aspartate/glutamate exchangers, AGCs, major components of the NADH malate aspartate shuttle (MAS) and urea cycle, and the ATP-Mg(2+)/Pi exchangers or short CaMCs (APCs or SCaMCs). The AGCs are activated by relatively low Ca(2+) levels only slightly higher than resting Ca(2+), whereas all SCaMCs studied so far require strong Ca(2+) signals, above micromolar, for activation. In addition, AGCs are not strictly Ca(2+) dependent, being active even in Ca(2+)-free conditions. Thus, AGCs are well suited to respond to small Ca(2+) signals and that do not reach mitochondria. In contrast, ATP-Mg(2+)/Pi carriers are inactive in Ca(2+) free conditions and activation requires Ca(2+) signals that will also activate the calcium uniporter (MCU). By changing the net content of adenine nucleotides of the matrix upon activation, SCaMCs regulate the activity of the permeability transition pore, and the Ca(2+) retention capacity of mitochondria (CRC), two functions synergizing with those of the MCU. The different Ca(2+) activation properties of the two CaMCs are discussed in relation to their newly obtained structures. This article is part of a Special Issue entitled: Mitochondrial Channels edited by Pierre Sonveaux, Pierre Maechler and Jean-Claude Martinou.
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Affiliation(s)
- Araceli Del Arco
- Facultad de Ciencias Ambientales y Bioquímica, Centro RegionaI de Investigaciones Biomédicas, Universidad de Castilla la Mancha, Toledo 45071, Spain; CIBER de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain; Instituto de Investigaciones Sanitarias Fundación Jiménez Díaz (IIS-FJD), Madrid, Spain
| | - Laura Contreras
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Científicas, 28049 Madrid, Spain; CIBER de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain; Instituto de Investigaciones Sanitarias Fundación Jiménez Díaz (IIS-FJD), Madrid, Spain
| | - Beatriz Pardo
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Científicas, 28049 Madrid, Spain; CIBER de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain; Instituto de Investigaciones Sanitarias Fundación Jiménez Díaz (IIS-FJD), Madrid, Spain
| | - Jorgina Satrustegui
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Científicas, 28049 Madrid, Spain; CIBER de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain; Instituto de Investigaciones Sanitarias Fundación Jiménez Díaz (IIS-FJD), Madrid, Spain.
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Islinger M, Grille S, Fahimi HD, Schrader M. The peroxisome: an update on mysteries. Histochem Cell Biol 2012; 137:547-74. [DOI: 10.1007/s00418-012-0941-4] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2012] [Indexed: 12/31/2022]
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Antonenkov VD, Hiltunen JK. Transfer of metabolites across the peroxisomal membrane. Biochim Biophys Acta Mol Basis Dis 2011; 1822:1374-86. [PMID: 22206997 DOI: 10.1016/j.bbadis.2011.12.011] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Revised: 12/08/2011] [Accepted: 12/15/2011] [Indexed: 02/08/2023]
Abstract
Peroxisomes perform a large variety of metabolic functions that require a constant flow of metabolites across the membranes of these organelles. Over the last few years it has become clear that the transport machinery of the peroxisomal membrane is a unique biological entity since it includes nonselective channels conducting small solutes side by side with transporters for 'bulky' solutes such as ATP. Electrophysiological experiments revealed several channel-forming activities in preparations of plant, mammalian, and yeast peroxisomes and in glycosomes of Trypanosoma brucei. The properties of the first discovered peroxisomal membrane channel - mammalian Pxmp2 protein - have also been characterized. The channels are apparently involved in the formation of peroxisomal shuttle systems and in the transmembrane transfer of various water-soluble metabolites including products of peroxisomal β-oxidation. These products are processed by a large set of peroxisomal enzymes including carnitine acyltransferases, enzymes involved in the synthesis of ketone bodies, thioesterases, and others. This review discusses recent data pertaining to solute permeability and metabolite transport systems in peroxisomal membranes and also addresses mechanisms responsible for the transfer of ATP and cofactors such as an ATP transporter and nudix hydrolases.
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Affiliation(s)
- Vasily D Antonenkov
- Department of Biochemistry and Biocenter, University of Oulu, Oulu, Finland.
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Wang Y, Zhu Y, Ling Y, Zhang H, Liu P, Baluška F, Šamaj J, Lin J, Wang Q. Disruption of actin filaments induces mitochondrial Ca2+ release to the cytoplasm and [Ca2+]c changes in Arabidopsis root hairs. BMC PLANT BIOLOGY 2010; 10:53. [PMID: 20334630 PMCID: PMC2923527 DOI: 10.1186/1471-2229-10-53] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Accepted: 03/24/2010] [Indexed: 05/19/2023]
Abstract
BACKGROUND Mitochondria are dynamic organelles that move along actin filaments, and serve as calcium stores in plant cells. The positioning and dynamics of mitochondria depend on membrane-cytoskeleton interactions, but it is not clear whether microfilament cytoskeleton has a direct effect on mitochondrial function and Ca2+ storage. Therefore, we designed a series of experiments to clarify the effects of actin filaments on mitochondrial Ca2+ storage, cytoplasmic Ca2+ concentration ([Ca2+]c), and the interaction between mitochondrial Ca2+ and cytoplasmic Ca2+ in Arabidopsis root hairs. RESULTS In this study, we found that treatments with latrunculin B (Lat-B) and jasplakinolide (Jas), which depolymerize and polymerize actin filaments respectively, decreased membrane potential and Ca2+ stores in the mitochondria of Arabidopsis root hairs. Simultaneously, these treatments induced an instantaneous increase of cytoplasmic Ca2+, followed by a continuous decrease. All of these effects were inhibited by pretreatment with cyclosporin A (Cs A), a representative blocker of the mitochondrial permeability transition pore (mPTP). Moreover, we found there was a Ca2+ concentration gradient in mitochondria from the tip to the base of the root hair, and this gradient could be disrupted by actin-acting drugs. CONCLUSIONS Based on these results, we concluded that the disruption of actin filaments caused by Lat-B or Jas promoted irreversible opening of the mPTP, resulting in mitochondrial Ca2+ release into the cytoplasm, and consequent changes in [Ca2+]c. We suggest that normal polymerization and depolymerization of actin filaments are essential for mitochondrial Ca2+ storage in root hairs.
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Affiliation(s)
- Yuqing Wang
- Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- Graduate School of Chinese Academy of Sciences, Beijing 100049, China
- College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China
| | - Yingfang Zhu
- Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- Graduate School of Chinese Academy of Sciences, Beijing 100049, China
| | - Yu Ling
- Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- Graduate School of Chinese Academy of Sciences, Beijing 100049, China
| | - Haiyan Zhang
- Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Peng Liu
- Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- Graduate School of Chinese Academy of Sciences, Beijing 100049, China
| | - František Baluška
- Institute of Cellular and Molecular Botany, University of Bonn, Department of Plant Cell Biology, Kirschallee 1, D-53115 Bonn, Germany
| | - Jozef Šamaj
- Centre of the Region Hana for Biotechnological and Agricultural Research, Faculty of Science, Palacky University, 78301 Olomouc, Czech Republic
| | - Jinxing Lin
- Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Qinli Wang
- Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
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Drago I, Giacomello M, Pizzo P, Pozzan T. Calcium Dynamics in the Peroxisomal Lumen of Living Cells. J Biol Chem 2008; 283:14384-90. [DOI: 10.1074/jbc.m800600200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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10
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Colasante C, Alibu VP, Kirchberger S, Tjaden J, Clayton C, Voncken F. Characterization and developmentally regulated localization of the mitochondrial carrier protein homologue MCP6 from Trypanosoma brucei. EUKARYOTIC CELL 2007; 5:1194-205. [PMID: 16896205 PMCID: PMC1539146 DOI: 10.1128/ec.00096-06] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Proteins of the mitochondrial carrier family (MCF) are located mainly in the inner mitochondrial membrane and mediate the transport of a large range of metabolic intermediates. The genome of Trypanosoma brucei harbors 29 genes encoding different MCF proteins. We describe here the characterization of MCP6, a novel T. brucei MCF protein. Sequence comparison and phylogenetic reconstruction revealed that MCP6 is closely related to different mitochondrial ADP/ATP and calcium-dependent solute carriers, including the ATP-Mg/Pi carrier of Homo sapiens. However, MCP6 lacks essential amino acids and sequence motifs conserved in these metabolite transporters, and functional reconstitution and transport assays with E. coli suggested that this protein indeed does not function as an ADP/ATP or ATP-Mg/Pi carrier. The subcellular localization of MCP6 is developmentally regulated: in bloodstream-form trypanosomes, the protein is predominantly glycosomal, whereas in the procyclic form, it is found mainly in the mitochondria. Depletion of MCP6 in procyclic trypanosomes resulted in growth inhibition, an increased cell size, aberrant numbers of nuclei and kinetoplasts, and abnormal kinetoplast morphology, suggesting that depletion of MCP6 inhibits division of the kinetoplast.
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Affiliation(s)
- Claudia Colasante
- Zentrum für Molekulare Biologie (ZMBH), Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
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Visser WF, van Roermund CWT, Ijlst L, Waterham HR, Wanders RJA. Metabolite transport across the peroxisomal membrane. Biochem J 2007; 401:365-75. [PMID: 17173541 PMCID: PMC1820816 DOI: 10.1042/bj20061352] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Accepted: 09/28/2006] [Indexed: 10/23/2022]
Abstract
In recent years, much progress has been made with respect to the unravelling of the functions of peroxisomes in metabolism, and it is now well established that peroxisomes are indispensable organelles, especially in higher eukaryotes. Peroxisomes catalyse a number of essential metabolic functions including fatty acid beta-oxidation, ether phospholipid biosynthesis, fatty acid alpha-oxidation and glyoxylate detoxification. The involvement of peroxisomes in these metabolic pathways necessitates the transport of metabolites in and out of peroxisomes. Recently, considerable progress has been made in the characterization of metabolite transport across the peroxisomal membrane. Peroxisomes posses several specialized transport systems to transport metabolites. This is exemplified by the identification of a specific transporter for adenine nucleotides and several half-ABC (ATP-binding cassette) transporters which may be present as hetero- and homo-dimers. The nature of the substrates handled by the different ABC transporters is less clear. In this review we will describe the current state of knowledge of the permeability properties of the peroxisomal membrane.
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Key Words
- fatty acid
- genetic disease
- metabolite
- peroxisome
- transport
- zellweger syndrome
- abc, atp-binding cassette
- cpt, carnitine palmitoyltransferase
- dhas, dihydroxyacetone synthetase
- dhca, dihydroxycholestanoic acid
- dnp, 2,4-dinitrophenol
- g3pdh, glycerol-3-phosphate dehydrogenase
- got, glutamate:aspartate aminotransferase
- lacs, long-chain acyl-coa synthetase
- mcf, mitochondrial carrier family
- mcfa, medium-chain fatty acid
- mct, monocarboxylate transporter
- mdh, malate dehydrogenase
- m-lp, mpv17-like protein
- pmp, peroxisomal membrane protein
- ros, reactive oxygen species
- scamc, short calcium-binding mitochondrial carrier
- thca, trihydroxycholestanoic acid
- xald, x-linked adrenoleukodystrophy
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Affiliation(s)
- Wouter F Visser
- University of Amsterdam, Academic Medical Centre, Department of Clinical Chemistry and Pediatrics, Laboratory Genetic Metabolic Diseases, F0-224, Meibergdreef 9, Amsterdam, 1105 AZ The Netherlands.
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12
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Contreras L, Gomez-Puertas P, Iijima M, Kobayashi K, Saheki T, Satrústegui J. Ca2+ Activation kinetics of the two aspartate-glutamate mitochondrial carriers, aralar and citrin: role in the heart malate-aspartate NADH shuttle. J Biol Chem 2007; 282:7098-106. [PMID: 17213189 DOI: 10.1074/jbc.m610491200] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ca(2+) regulation of the Ca(2+) binding mitochondrial carriers for aspartate/glutamate (AGCs) is provided by their N-terminal extensions, which face the intermembrane space. The two mammalian AGCs, aralar and citrin, are members of the malate-aspartate NADH shuttle. We report that their N-terminal extensions contain up to four pairs of EF-hand motifs plus a single vestigial EF-hand, and have no known homolog. Aralar and citrin contain one fully canonical EF-hand pair and aralar two additional half-pairs, in which a single EF-hand is predicted to bind Ca(2+). Shuttle activity in brain or skeletal muscle mitochondria, which contain aralar as the major AGC, is activated by Ca(2+) with S(0.5) values of 280-350 nm; higher than those obtained in liver mitochondria (100-150 nm) that contain citrin as the major AGC. We have used aralar- and citrin-deficient mice to study the role of the two isoforms in heart, which expresses both AGCs. The S(0.5) for Ca(2+) activation of the shuttle in heart mitochondria is about 300 nm, and it remains essentially unchanged in citrin-deficient mice, although it undergoes a drastic reduction to about 100 nm in aralar-deficient mice. Therefore, aralar and citrin, when expressed as single isoforms in heart, confer differences in Ca(2+) activation of shuttle activity, probably associated with their structural differences. In addition, the results reveal that the two AGCs fully account for shuttle activity in mouse heart mitochondria and that no other glutamate transporter can replace the AGCs in this pathway.
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Affiliation(s)
- Laura Contreras
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, C.S.I.C., 28049 Madrid, Spain
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13
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Satrústegui J, Pardo B, Del Arco A. Mitochondrial Transporters as Novel Targets for Intracellular Calcium Signaling. Physiol Rev 2007; 87:29-67. [PMID: 17237342 DOI: 10.1152/physrev.00005.2006] [Citation(s) in RCA: 203] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ca2+signaling in mitochondria is important to tune mitochondrial function to a variety of extracellular stimuli. The main mechanism is Ca2+entry in mitochondria via the Ca2+uniporter followed by Ca2+activation of three dehydrogenases in the mitochondrial matrix. This results in increases in mitochondrial NADH/NAD ratios and ATP levels and increased substrate uptake by mitochondria. We review evidence gathered more than 20 years ago and recent work indicating that substrate uptake, mitochondrial NADH/NAD ratios, and ATP levels may be also activated in response to cytosolic Ca2+signals via a mechanism that does not require the entry of Ca2+in mitochondria, a mechanism depending on the activity of Ca2+-dependent mitochondrial carriers (CaMC). CaMCs fall into two groups, the aspartate-glutamate carriers (AGC) and the ATP-Mg/Picarriers, also named SCaMC (for short CaMC). The two mammalian AGCs, aralar and citrin, are members of the malate-aspartate NADH shuttle, and citrin, the liver AGC, is also a member of the urea cycle. Both types of CaMCs are activated by Ca2+in the intermembrane space and function together with the Ca2+uniporter in decoding the Ca2+signal into a mitochondrial response.
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Affiliation(s)
- Jorgina Satrústegui
- Departamento de Biología Molecular Centro de Biología Molecular "Severo Ochoa" UAM-CSIC, Facultad de Ciencias, Universidad Autónoma, Madrid, Spain.
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14
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Colasante C, Ellis M, Ruppert T, Voncken F. Comparative proteomics of glycosomes from bloodstream form and procyclic culture form Trypanosoma brucei brucei. Proteomics 2006; 6:3275-93. [PMID: 16622829 DOI: 10.1002/pmic.200500668] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Peroxisomes are present in nearly every eukaryotic cell and compartmentalize a wide range of important metabolic processes. Glycosomes of Kinetoplastid parasites are peroxisome-like organelles, characterized by the presence of the glycolytic pathway. The two replicating stages of Trypanosoma brucei brucei, the mammalian bloodstream form (BSF) and the insect (procyclic) form (PCF), undergo considerable adaptations in metabolism when switching between the two different hosts. These adaptations involve also substantial changes in the proteome of the glycosome. Comparative (non-quantitative) analysis of BSF and PCF glycosomes by nano LC-ESI-Q-TOF-MS resulted in the validation of known functional aspects of glycosomes and the identification of novel glycosomal constituents.
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15
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Antonenkov VD, Sormunen RT, Hiltunen JK. The rat liver peroxisomal membrane forms a permeability barrier for cofactors but not for small metabolites in vitro. J Cell Sci 2005; 117:5633-42. [PMID: 15509867 DOI: 10.1242/jcs.01485] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The functional role of the peroxisomal membrane as a permeability barrier to metabolites has been a matter of controversy for more than four decades. The initial conception, claiming free permeability of the membrane to small solute molecules, has recently been challenged by several observations suggesting that the peroxisomal membrane forms a closed compartment. We have characterized in vitro the permeability of rat liver peroxisomal membrane. Our results indicate that the membrane allows free access into peroxisomes for small hydrophilic molecules, such as substrates for peroxisomal enzymes (glycolate, urate), but not to more bulky cofactors (NAD/H, NADP/H, CoA). Although access for cofactors is not prevented completely by the membrane, the membrane barrier severely restricts their rate of entry into peroxisomes. The data lead to conclusion that, in vivo, peroxisomes may possess their own pool of cofactors, while they share a common pool of small metabolites with the cytoplasm. The results also indicate that molecular size plays an important role in in vivo distinction between cofactors and metabolic intermediates.
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Affiliation(s)
- Vasily D Antonenkov
- Department of Biochemistry and Biocenter Oulu, University of Oulu, PO Box 3000, FI-90014, Oulu, Finland
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16
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Bassi MT, Manzoni M, Bresciani R, Pizzo MT, Della Monica A, Barlati S, Monti E, Borsani G. Cellular expression and alternative splicing of SLC25A23, a member of the mitochondrial Ca2+-dependent solute carrier gene family. Gene 2005; 345:173-82. [PMID: 15716113 DOI: 10.1016/j.gene.2004.11.028] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2004] [Revised: 09/27/2004] [Accepted: 11/17/2004] [Indexed: 11/24/2022]
Abstract
The transport of metabolites across the inner mitochondrial membrane is mediated by a large superfamily of mitochondrial solute carrier (MSC) proteins. A novel human member of the MSC gene family named SLC25A23, with homologs in mammalian and non-mammalian species has been recently identified together with two close paralogs, SLC25A24 and SLC25A25. These genes encode the human isoforms of the ATP-Mg/Pi carrier described in whole mitochondria. We report here the cellular expression and alternative splicing of SLC25A23. The gene encodes a 468 amino acids polypeptide, named SCaMC-3, with a bipartite structure typical of calcium-binding mitochondrial solute carrier (CaMSC) proteins. The amino-terminal portion harbors three canonical EF-hand calcium-binding domains while the carboxyl-terminal portion of SCaMC-3 has the characteristic features of the MSC superfamily. Northern blot analysis reveals the presence of the transcript in brain, heart, skeletal muscle, liver and small intestine. The SLC25A23 gene undergoes alternative splicing suggesting a modular nature of the encoded product. Three out of four putative protein isoforms lack a significant portion of the third mitochondrial carrier signature. The most common SCaMC-3 isoform shows a mitochondrial subcellular localization when transfected in HeLa cells and is able to bind calcium by Ca(2+)-dependent mobility shift assays. We believe that our study will contribute to a better knowledge of this family of mitochondrial carriers.
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Affiliation(s)
- Maria Teresa Bassi
- Istituto Scientifico Eugenio Medea "La Nostra Famiglia", Via Don Luigi Monza, 20 22040 Bosisio Parini (LC), Italy
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17
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Fiermonte G, De Leonardis F, Todisco S, Palmieri L, Lasorsa FM, Palmieri F. Identification of the mitochondrial ATP-Mg/Pi transporter. Bacterial expression, reconstitution, functional characterization, and tissue distribution. J Biol Chem 2004; 279:30722-30. [PMID: 15123600 DOI: 10.1074/jbc.m400445200] [Citation(s) in RCA: 161] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mitochondrial carriers are a family of transport proteins that, with a few exceptions, are found in the inner membranes of mitochondria. They shuttle metabolites, nucleotides, and cofactors through this membrane and thereby connect and/or regulate cytoplasm and matrix functions. ATP-Mg is transported in exchange for phosphate, but no protein has ever been associated with this activity. We have isolated three human cDNAs that encode proteins of 458, 468, and 489 amino acids with 66-75% similarity and with the characteristic features of the mitochondrial carrier family in their C-terminal domains and three EF-hand Ca(2+)-binding motifs in their N-terminal domains. These proteins have been overexpressed in Escherichia coli and reconstituted into phospholipid vesicles. Their transport properties and their targeting to mitochondria demonstrate that they are isoforms of the ATP-Mg/Pi carrier described in the past in whole mitochondria. The tissue specificity of the three isoforms shows that at least one isoform was present in all of the tissues investigated. Because phosphate recycles via the phosphate carrier in mitochondria, the three isoforms of the ATP-Mg/Pi carrier are most likely responsible for the net uptake or efflux of adenine nucleotides into or from the mitochondria and hence for the variation in the matrix adenine nucleotide content, which has been found to change in many physiopathological situations.
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Affiliation(s)
- Giuseppe Fiermonte
- Department of Pharmaco-Biology, Laboratory of Biochemistry and Molecular Biology, University of Bari, Via Orabona 4, Italy
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18
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del Arco A, Satrústegui J. Identification of a novel human subfamily of mitochondrial carriers with calcium-binding domains. J Biol Chem 2004; 279:24701-13. [PMID: 15054102 DOI: 10.1074/jbc.m401417200] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Aralar1 and citrin were identified as calcium binding aspartate/glutamate carriers (AGC) in mitochondria. The presence of calcium binding motifs facing the extramitochondrial space allows the regulation of the transport activity of these carriers by cytosolic calcium and provides a new mechanism to transduce calcium signals in mitochondria without the requirement of calcium entry in the organelle. We now report the complete characterization of a second subfamily of human calcium binding mitochondrial carriers named SCaMC (short calcium-binding mitochondrial carriers). We have identified three SCaMC genes in the human genome. All code for highly conserved proteins (about 70-80% identity), of about 500 amino acids with a characteristic mitochondrial carrier domain at the C terminus, and an N-terminal extension harboring four EF-hand binding motifs with high similarity to calmodulin. All SCaMC proteins were found to be located exclusively in mitochondria, and their N-terminal extensions were dispensable for the correct mitochondrial targeting of the polypeptides. SCaMC-1 is the human orthologue of the rabbit Efinal protein, which was reported to be located in peroxisomes, and SCaMC-2 is the human orthologue of the rat MCSC protein, described as up-regulated by dexamethasone in AR42J cells. One of the SCaMC genes, SCaMC-2, has four variants generated by alternative splicing, resulting in proteins with a common C terminus but with variations in their N-terminal halves, including the loss of one to three EF-hand motifs. These results make SCaMC one of most complex subfamilies of mitochondrial carriers and suggest that the large number of isoforms and splice variants may confer different calcium sensitivity to the transport activity of these carriers.
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Affiliation(s)
- Araceli del Arco
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Universidad Autónoma, 28049 Madrid, Spain.
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19
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Camacho JA, Rioseco-Camacho N, Andrade D, Porter J, Kong J. Cloning and characterization of human ORNT2: a second mitochondrial ornithine transporter that can rescue a defective ORNT1 in patients with the hyperornithinemia-hyperammonemia-homocitrullinuria syndrome, a urea cycle disorder. Mol Genet Metab 2003; 79:257-71. [PMID: 12948741 DOI: 10.1016/s1096-7192(03)00105-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We recently characterized the mitochondrial ornithine transporter (ORNT1), the gene defective in the hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome, a urea cycle disorder. Despite the apparent functional ablation of ORNT1 in 10 French-Canadian probands with the ORNT1-F188 Delta allele, these patients are mildly affected when compared to patients with other urea cycle disorders such as deficiency of ornithine transcarbamylase. Given that the inner mitochondrial membrane is impermeable to solutes, we hypothesize that other unidentified carriers have some degree of functional redundancy with ORNT1. Using conserved sequences of mammalian and fungal mitochondrial ornithine transporters, we screened the Expressed Sequence Tag database for additional transporters belonging to the ORNT subfamily. Here we identify a new intronless gene, ORNT2, located on chromosome 5. The gene product of ORNT2 is 88% identical to ORNT1, targets to the mitochondria and is expressed in human liver, pancreas, kidney, and cultured fibroblasts from control and HHH patients. When ORNT2 is overexpressed transiently in cultured fibroblasts from HHH patients, it rescues the deficient ornithine metabolism in these cells. Our results suggest that ORNT2 may in part be responsible for the milder phenotype in HHH patients secondary to a gene redundancy effect. We believe ORNT2 arose from a retrotransposition event. To our knowledge, this is the first report of a functional retroposon (ORNT2) that can rescue the disease phenotype of the gene it arose from, ORNT1. As such, ORNT2 may eventually become a candidate for pharmacological-based approaches to correct a urea cycle disorder.
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Affiliation(s)
- José A Camacho
- Department of Pediatrics, University of Oklahoma Health Sciences Center, 975 N.E. 10th Street, Biomedical Research Center, Room BRC-256, Oklahoma City, OK 73104, USA.
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20
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Cunningham O, McElligott AM, Carroll AM, Breen E, Reguenga C, Oliveira MEM, Azevedo JE, Porter RK. Selective detection of UCP 3 expression in skeletal muscle: effect of thyroid status and temperature acclimation. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1604:170-9. [PMID: 12837549 DOI: 10.1016/s0005-2728(03)00057-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A novel peptide antibody to UCP 3 is characterized which is sensitive and discriminatory for UCP 3 over UCP 2, UCP 1 and other mitochondrial transporters. The peptide antibody detects UCP 3 expression in E. coli, COS cells and yeast expression systems. The peptide antibody detects a single approximately 33 kDa protein band in mitochondria from isolated rat skeletal muscle, mouse and rat brown adipose tissue, and in whole muscle groups (soleus and extensor digitorum longus) from mice. No 33 kDa band is detectable in isolated mitochondria from liver, heart, brain, kidney and lungs of rats, or gastrocnemius mitochondria from UCP 3 knock-out mice. From our data, we conclude that the peptide antibody is detecting UCP 3 in skeletal muscle, skeletal muscle mitochondria and brown adipose tissue mitochondria. It is also noteworthy that the peptide antibody can detect human, mouse and rat forms of UCP 3. Using the UCP 3 peptide antibody, we confirm and quantify the increased (2.8-fold) UCP 3 expression observed in skeletal muscle mitochondria isolated from 48-h-starved rats. We show that UCP 3 expression is increased (1.6-fold) in skeletal muscle of rats acclimated over 8 weeks to 8 degrees C and that UCP 3 expression is decreased (1.4-fold) in rats acclimated to 30 degrees C. Furthermore, UCP 3 expression is increased (2.3-fold) in skeletal muscle from hyperthyroid rats compared to euthyroid controls. In addition, we show that UCP 3 expression is only coincident with the mitochondrial fraction of skeletal muscle homogenates and not peroxisomal, nuclear or cytosolic and microsomal fractions.
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Affiliation(s)
- O Cunningham
- Department of Biochemistry, Trinity College Dublin, Biotechnology Building, Room 0.16, Dublin 2, Ireland
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21
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Mashima H, Ueda N, Ohno H, Suzuki J, Ohnishi H, Yasuda H, Tsuchida T, Kanamaru C, Makita N, Iiri T, Omata M, Kojima I. A novel mitochondrial Ca2+-dependent solute carrier in the liver identified by mRNA differential display. J Biol Chem 2003; 278:9520-7. [PMID: 12645546 DOI: 10.1074/jbc.m208398200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pancreatic AR42J cells have the feature of pluripotency of the precursor cells of the gut endoderm. Dexamethasone converts them to exocrine cells or liver cells. Using mRNA differential display techniques, we have identified a novel Ca2+-dependent member of the mitochondrial solute carrier superfamily, which is expressed during the course of differentiation, and have designated it MCSC. The corresponding cDNA comprises an open reading frame of 1407 base pairs encoding a polypeptide of 469 amino acids. The carboxyl-terminal-half of MCSC has high similarity with other mitochondrial carriers, and the amino-terminal-half has three canonical elongation factor-hand motifs and has calcium binding capacity. The deduced amino acid sequence revealed 79.1% homology to the rabbit peroxisomal Ca2+-dependent member of the mitochondrial superfamily, but the subcellular localization of the protein was exclusively mitochondrial, not peroxisomal. Northern blot and Western blot analyses revealed its predominant expression in the liver and the skeletal muscle. In the liver, the expression level of MCSC was higher in the adult stage than in the fetal stage, and MCSC was highly up-regulated in dexamethasone-treated AR42J cells before the expression of albumin. Taken together, MCSC may play an important role in regulating the function of hepatocytes rather than in differentiation in vivo.
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Affiliation(s)
- Hirosato Mashima
- Department of Gastroenterology, University of Tokyo School of Medicine, Tokyo 113-8655, Japan.
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22
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Millar AH, Heazlewood JL. Genomic and proteomic analysis of mitochondrial carrier proteins in Arabidopsis. PLANT PHYSIOLOGY 2003; 131:443-53. [PMID: 12586869 PMCID: PMC166821 DOI: 10.1104/pp.009985] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2002] [Revised: 07/31/2002] [Accepted: 11/03/2002] [Indexed: 05/17/2023]
Abstract
Plant mitochondria maintain metabolic communication with the cytosol through a family of carrier proteins. In Arabidopsis, a subset of 45 putative genes encoding members of this family have been identified based on generalized mitochondrial carrier features. No gene clusters are apparent and few of the predicted protein products have mitochondrial targeting sequences recognized by bioinformatic predictors. Only nine genes are currently represented by more than 10 expressed sequence tags at The Institute for Genomic Research. Analyses of public microarray experiments reveal differential expression profiles of the more highly expressed members of this gene family in different plant organs and in response to plant hormone application and environmental stresses. A comparison of this Arabidopsis carrier subset (45) to the yeast gene family (35) reveals 10 orthologous groups between the two species. Recent surveys of the Arabidopsis mitochondrial proteome by two-dimensional gel separations have not identified any of these carrier proteins, presumably because of their hydrophobicity and basicity. Isolating integral membrane proteins from Arabidopsis mitochondria, using one-dimensional electrophoresis for protein separation and tandem mass spectrometry-based sequencing of doubly charged peptides, we have unequivocally identified specific carrier gene products located in mitochondria. This approach has identified six of the nine carriers represented highly in expressed sequence tag databases: adenine nucleotide translocator (At3g8580 and At5g13490), dicarboxylate/tricarboxylate carrier (At5g19760), phosphate carrier (At5g14040), uncoupling protein (At3g54110), and a carrier gene of unknown function (At4g01100). Overall, the combined transcript and protein expression data indicates that only a small subset of the carrier family of genes provide the majority of carrier proteins of Arabidopsis mitochondria.
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Affiliation(s)
- A Harvey Millar
- Plant Molecular Biology Group, School of Biomedical and Chemical Sciences, The University of Western Australia, Crawley 6009, Western Australia, Australia.
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23
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Igamberdiev AU, Lea PJ. The role of peroxisomes in the integration of metabolism and evolutionary diversity of photosynthetic organisms. PHYTOCHEMISTRY 2002; 60:651-674. [PMID: 12127583 DOI: 10.1016/s0031-9422(02)00179-6] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The peroxisome is a metabolic compartment serving for the rapid oxidation of substrates, a process that is not coupled to energy conservation. In plants and algae, peroxisomes connect biosynthetic and oxidative metabolic routes and compartmentalize potentially lethal steps of metabolism such as the formation of reactive oxygen species and glyoxylate, thus preventing poisoning of the cell and futile recycling. Peroxisomes exhibit properties resembling inside-out vesicles and possess special systems for the import of specific proteins, which form multi-enzyme complexes (metabolons) linking numerous reactions to flavin-dependent oxidation, coupled to the decomposition of hydrogen peroxide by catalase. Hydrogen peroxide and superoxide originating in peroxisomes are important mediators in signal transduction pathways, particularly those involving salicylic acid. By contributing to the synthesis of oxalate, formate and other organic acids, peroxisomes regulate major fluxes of primary and secondary metabolism. The evolutionary diversity of algae has led to the presence of a wide range of enzymes in the peroxisomes that are only similar to higher plants in their direct predecessors, the Charophyceae. The appearance of seed plants was connected to the acquirement by storage tissues, of a peroxisomal fatty acid oxidation function linked to the glyoxylate cycle, which is induced during seed germination and maturation. Rearrangement of the peroxisomal photorespiratory function between different tissues of higher plants led to the appearance of different types of photosynthetic metabolism. The peroxisome may therefore have played a key role in the evolutionary formation of metabolic networks, via establishing interconnections between different metabolic compartments.
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Affiliation(s)
- Abir U Igamberdiev
- Plant Research Department, Risø National Laboratory, 4000, Roskilde, Denmark.
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24
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Kim-Han JS, Reichert SA, Quick KL, Dugan LL. BMCP1: a mitochondrial uncoupling protein in neurons which regulates mitochondrial function and oxidant production. J Neurochem 2001; 79:658-68. [PMID: 11701769 DOI: 10.1046/j.1471-4159.2001.00604.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Outside the nervous system, members of the mitochondrial uncoupling protein (UCP) family have been proposed to contribute to control of body temperature and energy metabolism, and regulation of mitochondrial production of reactive oxygen species (ROS). However, the function of brain mitochondrial carrier protein 1 (BMCP1), which is highly expressed in brain, remains to be determined. To study BMCP1 expression and function in the nervous system, a high-affinity antibody to BMCP1 was generated and used to analyze tissue expression of BMCP1 protein in mouse. BMCP1 protein was highly expressed in heart and kidney, but not liver or lung. In the nervous system, BMCP1 was present in cortex, basal ganglia, substantia nigra, cerebellum, and spinal cord. Both BMCP1 mRNA and protein expression was almost exclusively neuronal. To study the effect of BMCP1 expression on mitochondrial function, neuronal (GT1-1) cell lines with stable overexpression of BMCP1 were generated. Transfected cells had higher State 4 respiration and lower mitochondrial membrane potential (psi(m)), consistent with greater mitochondrial uncoupling. BMCP1 expression also decreased mitochondrial production of ROS. These data suggest that BMCP1 can modify mitochondrial respiratory efficiency and mitochondrial oxidant production, and raise the possibility that BMCP1 might alter the vulnerability of brain to both acute injury and to neurodegenerative conditions.
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Affiliation(s)
- J S Kim-Han
- Department of Neurology and Center for the Study of Nervous System Disease, Washington University School of Medicine, St Louis, Missouri 63110, USA
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25
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Werder M, Han CH, Wehrli E, Bimmler D, Schulthess G, Hauser H. Role of scavenger receptors SR-BI and CD36 in selective sterol uptake in the small intestine. Biochemistry 2001; 40:11643-50. [PMID: 11560515 DOI: 10.1021/bi0109820] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The serum lipoprotein high-density lipoprotein (HDL), which is a ligand of scavenger receptors such as scavenger receptor class B type I (SR-BI) and cluster determinant 36 (CD36), can act as a donor particle for intestinal lipid uptake into the brush border membrane (BBM). Both cholesterol and phospholipids are taken up by the plasma membrane of BBM vesicles (BBMV) and Caco-2 cells in a facilitated (protein-mediated) process. The protein-mediated transfer of cholesterol from reconstituted HDL to BBMV depends on the lipid composition of the HDL. In the presence of sphingomyelin, the transfer of cholesterol is slowed by a factor of about 3 probably due to complex formation between cholesterol and the sphingolipid. It is shown that the mechanism of lipid transfer from reconstituted HDL to either BBMV or Caco-2 cells as the acceptor is consistent with selective lipid uptake: the lipid donor docks at the membrane-resident scavenger receptors which mediate the transfer of lipids between donor and acceptor. Selective lipid uptake implies that lipid, but no apoprotein is transferred from the donor to the BBM, thus excluding endocytotic processes. The two BBM models used here clearly indicate that fusion of donor particles with the BBM can be ruled out as a major mechanism contributing to intestinal lipid uptake. Here we demonstrate that CD36, another member of the family of scavenger receptors, is present in rabbit and human BBM vesicles. This receptor mediates the uptake of free cholesterol, but not of esterified cholesterol, the uptake of which is mediated exclusively by SR-BI. More than one scavenger receptor appears to be involved in the uptake of free cholesterol with SR-BI contributing about 25% and CD36 about 35%. There is another yet unidentified protein accounting for the remaining 30 to 40%.
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Affiliation(s)
- M Werder
- Institute of Biochemistry, Swiss Federal Institute of Technology, ETH Center, Universitätstrasse 16, CH-8092 Zurich, Switzerland
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26
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Palmieri L, Rottensteiner H, Girzalsky W, Scarcia P, Palmieri F, Erdmann R. Identification and functional reconstitution of the yeast peroxisomal adenine nucleotide transporter. EMBO J 2001; 20:5049-59. [PMID: 11566870 PMCID: PMC125274 DOI: 10.1093/emboj/20.18.5049] [Citation(s) in RCA: 163] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The requirement for small molecule transport systems across the peroxisomal membrane has previously been postulated, but not directly proven. Here we report the identification and functional reconstitution of Ant1p (Ypr128cp), a peroxisomal transporter in the yeast Saccharomyces cerevisiae, which has the characteristic sequence features of the mitochondrial carrier family. Ant1p was found to be an integral protein of the peroxisomal membrane and expression of ANT1 was oleic acid inducible. Targeting of Ant1p to peroxisomes was dependent on Pex3p and Pex19p, two peroxins specifically required for peroxisomal membrane protein insertion. Ant1p was essential for growth on medium-chain fatty acids as the sole carbon source. Upon reconstitution of the overexpressed and purified protein into liposomes, specific transport of adenine nucleotides could be demonstrated. Remarkably, both the substrate and inhibitor specificity differed from those of the mitochondrial ADP/ATP transporter. The physiological role of Ant1p in S.cerevisiae is probably to transport cytoplasmic ATP into the peroxisomal lumen in exchange for AMP generated in the activation of fatty acids.
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Affiliation(s)
| | - Hanspeter Rottensteiner
- Department of Pharmaco-Biology, Laboratory of Biochemistry and Molecular Biology, University of Bari, Via E. Orabona 4, 70125 Bari, Italy and
Institute of Chemistry/Biochemistry, Free University of Berlin, Thielallee 63, 14195 Berlin, Germany Present address: Institute of Physiological Chemistry, Ruhr-University Bochum, 44780 Bochum, Germany Corresponding author e-mail:
L.Palmieri and H.Rottensteiner contributed equally to this work
| | - Wolfgang Girzalsky
- Department of Pharmaco-Biology, Laboratory of Biochemistry and Molecular Biology, University of Bari, Via E. Orabona 4, 70125 Bari, Italy and
Institute of Chemistry/Biochemistry, Free University of Berlin, Thielallee 63, 14195 Berlin, Germany Present address: Institute of Physiological Chemistry, Ruhr-University Bochum, 44780 Bochum, Germany Corresponding author e-mail:
L.Palmieri and H.Rottensteiner contributed equally to this work
| | | | | | - Ralf Erdmann
- Department of Pharmaco-Biology, Laboratory of Biochemistry and Molecular Biology, University of Bari, Via E. Orabona 4, 70125 Bari, Italy and
Institute of Chemistry/Biochemistry, Free University of Berlin, Thielallee 63, 14195 Berlin, Germany Present address: Institute of Physiological Chemistry, Ruhr-University Bochum, 44780 Bochum, Germany Corresponding author e-mail:
L.Palmieri and H.Rottensteiner contributed equally to this work
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27
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Honsho M, Fujiki Y. Topogenesis of peroxisomal membrane protein requires a short, positively charged intervening-loop sequence and flanking hydrophobic segments. study using human membrane protein PMP34. J Biol Chem 2001; 276:9375-82. [PMID: 11121399 DOI: 10.1074/jbc.m003304200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human 34-kDa peroxisomal membrane protein (PMP34) consisting of 307 amino acids was previously identified as an ortholog of, or a similar protein (with 27% identity) to the, 423-amino acid-long PMP47 of the yeast Candida boidinii. We investigated membrane topogenesis of PMP34 with six putative transmembrane segments, as a model peroxisomal membrane protein. PMP34 was characterized as an integral membrane protein of peroxisomes. Transmembrane topology of PMP34 was determined by differential permeabilization and immunofluorescent staining of HeLa cells ectopically expressing PMP34 as well as of Chinese hamster ovary-K1 expressing epitope-tagged PMP34. As opposed to PMP47, PMP34 was found to expose its N- and C-terminal parts to the cytosol. Various deletion variants of PMP34 and their fusion proteins with green fluorescent protein were expressed in Chinese hamster ovary-K1 and were verified with respect to intracellular localization. The loop region between transmembrane segments 4 and 5 was required for the peroxisome-targeting activity, in which Ala substitution for basic residues abrogated the activity. Three hydrophobic transmembrane segments linked in a flanking region of the basic loop were essential for integration of PMP34 to peroxisome membranes. Therefore, it is evident that the intervening basic loop plus three transmembrane segments of PMP34 function as a peroxisomal targeting and topogenic signal.
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Affiliation(s)
- M Honsho
- Department of Biology, Faculty of Sciences, Kyushu University Graduate School, Fukuoka 812-8581, Japan
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28
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Belenkiy R, Haefele A, Eisen MB, Wohlrab H. The yeast mitochondrial transport proteins: new sequences and consensus residues, lack of direct relation between consensus residues and transmembrane helices, expression patterns of the transport protein genes, and protein-protein interactions with other proteins. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1467:207-18. [PMID: 10930523 DOI: 10.1016/s0005-2736(00)00222-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mitochondrial transport proteins (MTP) typically are homodimeric with a 30-kDa subunit with six transmembrane helices. The subunit possesses a sequence motif highly similar to Pro X Asp/Glu X X Lys/Arg X Arg within each of its three similar 10-kDa segments. Four (YNL083W, YFR045W, YPR021C, YDR470C) of the 35 yeast (S. cerevisiae) MTP genes were resequenced since the masses of their proteins deviate significantly from the typical 30 kDa. We now find these four proteins to have 545, 285, 902, and 502 residues, respectively. Together with only four other MTPs, the sequences of YPR021C and YDR470C show substitutions of some of the five residues that are absolutely conserved among the 12 MTPs with identified transport function and 17 other MTPs. We do now find these five consensus residues also in the new sequences of YNL083W and YFR045W. Additional analyses of the 35 yeast MTPs show that the location of transmembrane helix sequences do not correlate with the general consensus residues of the MTP family; protein segments connecting the six transmembrane helices and facing the intermembrane space are not uniformly short (about 20 residues) or long (about 40 residues) when facing the matrix; most MTPs have at least one transmembrane helix for which the sum of the negative hydropathy values of all residues yields a very small negative value, suggesting a membrane location bordering polar faces of other transmembrane helices or a non-transmembrane location. The extra residues of the three large MTPs are hydrophilic and at the N-terminal. The 200-residue N-terminal segment of YNL083W has four putative Ca2+-binding sites. The 500-residue N-terminal segment of YPR021C shows sequence similarity to enzymes of nucleic acid metabolism. cDNA microarray data show that YNL083W is expressed solely during sporulation, while the expressions of YFR045W, YPR021C, and YDR470C are induced by various stress situations. These results also show that the 35 MTP genes are expressed under a rather diverse set of metabolic conditions that may help identify the function of the proteins. Interestingly, yeast two-hybrid screens, that will also be useful in identifying the function of MTPs, indicate that MIR1, AAC3, YOR100C, and YPR011C do interact with non-MTPs.
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Affiliation(s)
- R Belenkiy
- Boston Biomedical Research Institute and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Watertown, MA 02472, USA
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29
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Baerends RJ, Faber KN, Kiel JA, van der Klei IJ, Harder W, Veenhuis M. Sorting and function of peroxisomal membrane proteins. FEMS Microbiol Rev 2000; 24:291-301. [PMID: 10841974 DOI: 10.1111/j.1574-6976.2000.tb00543.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Peroxisomes are subcellular organelles and are present in virtually all eukaryotic cells. Characteristic features of these organelles are their inducibility and their functional versatility. Their importance in the intermediary metabolism of cells is exemplified by the discovery of several inborn, fatal peroxisomal errors in man, the so-called peroxisomal disorders. Recent findings in research on peroxisome biogenesis and function have demonstrated that peroxisomal matrix proteins and peroxisomal membrane proteins (PMPs) follow separate pathways to reach their target organelle. This paper addresses the principles of PMP sorting and summarizes the current knowledge of the role of these proteins in organelle biogenesis and function.
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Affiliation(s)
- R J Baerends
- Eukaryotic Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, Postbus 14, 9750 AA, Haren, The Netherlands
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30
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Dyall SD, Koehler CM, Delgadillo-Correa MG, Bradley PJ, Plümper E, Leuenberger D, Turck CW, Johnson PJ. Presence of a member of the mitochondrial carrier family in hydrogenosomes: conservation of membrane-targeting pathways between hydrogenosomes and mitochondria. Mol Cell Biol 2000; 20:2488-97. [PMID: 10713172 PMCID: PMC85448 DOI: 10.1128/mcb.20.7.2488-2497.2000] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A number of microaerophilic eukaryotes lack mitochondria but possess another organelle involved in energy metabolism, the hydrogenosome. Limited phylogenetic analyses of nuclear genes support a common origin for these two organelles. We have identified a protein of the mitochondrial carrier family in the hydrogenosome of Trichomonas vaginalis and have shown that this protein, Hmp31, is phylogenetically related to the mitochondrial ADP-ATP carrier (AAC). We demonstrate that the hydrogenosomal AAC can be targeted to the inner membrane of mitochondria isolated from Saccharomyces cerevisiae through the Tim9-Tim10 import pathway used for the assembly of mitochondrial carrier proteins. Conversely, yeast mitochondrial AAC can be targeted into the membranes of hydrogenosomes. The hydrogenosomal AAC contains a cleavable, N-terminal presequence; however, this sequence is not necessary for targeting the protein to the organelle. These data indicate that the membrane-targeting signal(s) for hydrogenosomal AAC is internal, similar to that found for mitochondrial carrier proteins. Our findings indicate that the membrane carriers and membrane protein-targeting machinery of hydrogenosomes and mitochondria have a common evolutionary origin. Together, they provide strong evidence that a single endosymbiont evolved into a progenitor organelle in early eukaryotic cells that ultimately give rise to these two distinct organelles and support the hydrogen hypothesis for the origin of the eukaryotic cell.
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Affiliation(s)
- S D Dyall
- Department of Microbiology and Immunology, University of California, Los Angeles, California 90095, USA
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31
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Del Arco A, Agudo M, Satrústegui J. Characterization of a second member of the subfamily of calcium-binding mitochondrial carriers expressed in human non-excitable tissues. Biochem J 2000; 345 Pt 3:725-32. [PMID: 10642534 PMCID: PMC1220810 DOI: 10.1042/0264-6021:3450725] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We have recently identified a subfamily of mitochondrial carriers that bind calcium, and cloned ARALAR1, a member of this subfamily expressed in human muscle and brain. We have now cloned a second human ARALAR gene (ARALAR2) coding for a protein 78.3% identical to Aralar1, but expressed in liver and non-excitable tissues. Aralar2 is identical to citrin, the product of the gene mutated in type-II citrullinaemia [Kobayashi, Sinasac, Iijima, Boright, Begum, Lee, Yasuda, Ikeda, Hirano, Terazono et al. (1999) Nat. Genet. 22, 159-163]. A related protein, DmAralar, 69% identical to Aralar1, was found in Drosophila melanogaster, the DMARALAR locus lying on the right arm of the third chromosome, band 99F. The N-terminal half of Aralar2/citrin is able to bind calcium and this requires the presence of the two most distal EF-hands. The localization of Aralar2/citrin expressed in human cell lines is mitochondrial, the C-terminal half containing sufficient information for import and assembly into mitochondria. The C-terminal half of Aralar proteins is related to the yeast YPR020c gene, with a very high sequence conservation (54.3% identity), suggesting that these proteins play an important role. Thus Aralar proteins are probably expressed in all tissues in an isoform-specific fashion, where they function as calcium-regulated metabolite (possibly anionic) carriers.
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Affiliation(s)
- A Del Arco
- Departamento de Biología Molecular, Centro de Biología Molecular 'Severo Ochoa', Campus de Cantoblanco, 28049-Madrid, Spain
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32
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Ricquier D, Bouillaud F. The uncoupling protein homologues: UCP1, UCP2, UCP3, StUCP and AtUCP. Biochem J 2000; 345 Pt 2:161-79. [PMID: 10620491 PMCID: PMC1220743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Animal and plant uncoupling protein (UCP) homologues form a subfamily of mitochondrial carriers that are evolutionarily related and possibly derived from a proton/anion transporter ancestor. The brown adipose tissue (BAT) UCP1 has a marked and strongly regulated uncoupling activity, essential to the maintenance of body temperature in small mammals. UCP homologues identified in plants are induced in a cold environment and may be involved in resistance to chilling. The biochemical activities and biological functions of the recently identified mammalian UCP2 and UCP3 are not well known. However, recent data support a role for these UCPs in State 4 respiration, respiration uncoupling and proton leaks in mitochondria. Moreover, genetic studies suggest that UCP2 and UCP3 play a part in energy expenditure in humans. The UCPs may also be involved in adaptation of cellular metabolism to an excessive supply of substrates in order to regulate the ATP level, the NAD(+)/NADH ratio and various metabolic pathways, and to contain superoxide production. A major goal will be the analysis of mice that either lack the UCP2 or UCP3 gene or overexpress these genes. Other aims will be to investigate the possible roles of UCP2 and UCP3 in response to oxidative stress, lipid peroxidation, inflammatory processes, fever and regulation of temperature in certain specific parts of the body.
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Affiliation(s)
- D Ricquier
- Centre de Recherche sur l'Endocrinologie Moléculaire et le Développement (CEREMOD), Centre National de la recherche Scientifique (CNRS-Unit 9078), 9 rue Jules Hetzel, 92190 Meudon, France.
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33
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Gouveia AM, Reguenga C, Oliveira ME, Eckerskorn C, Sá-Miranda C, Azevedo JE. Alkaline density gradient floatation of membranes: polypeptide composition of the mammalian peroxisomal membrane. Anal Biochem 1999; 274:270-7. [PMID: 10527525 DOI: 10.1006/abio.1999.4281] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A method for purification of the peroxisomal membrane from rat liver is described. The procedure consists of floating the (contaminated) peroxisomal membranes through an alkaline sucrose density gradient. A good resolution between the peroxisomal membrane and other membrane systems is achieved. Using these floated peroxisomal membranes we have determined that only 7.8 +/- 0.9% of the total peroxisomal protein is alkali resistant. The polypeptide composition of these highly pure peroxisomal membranes was analyzed by SDS-PAGE. Bands corresponding to polypeptides with apparent molecular masses of 15, 18, 22, 24, 26, 29, 35, 36, 38, 40, 52, 55, 70, 74-77, and 88 kDa are detected upon Coomassie blue staining of polyacrylamide gels. The identity of several of these polypeptides was determined by N-terminal sequencing and Western blotting analysis.
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Affiliation(s)
- A M Gouveia
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
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34
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Camacho JA, Obie C, Biery B, Goodman BK, Hu CA, Almashanu S, Steel G, Casey R, Lambert M, Mitchell GA, Valle D. Hyperornithinaemia-hyperammonaemia-homocitrullinuria syndrome is caused by mutations in a gene encoding a mitochondrial ornithine transporter. Nat Genet 1999; 22:151-8. [PMID: 10369256 DOI: 10.1038/9658] [Citation(s) in RCA: 140] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Neurospora crassa ARG13 and Saccharomyces cerevisiae ARG11 encode mitochondrial carrier family (MCF) proteins that transport ornithine across the mitochondrial inner membrane. We used their sequences to identify EST candidates that partially encode orthologous mammalian transporters. We thereby identified such a gene (ORNT1) that maps to 13q14 and whose expression, similar to that of other urea cycle (UC) components, was high in liver and varied with changes in dietary protein. ORNT1 expression restores ornithine metabolism in fibroblasts from patients with hyperammonaemia-hyperornithinaemia-homocitrullinuria (HHH) syndrome. In a survey of 11 HHH probands, we identified 3 ORNT1 mutant alleles that account for 21 of 22 possible mutant ORNT1 genes in our patients: F188delta, which is common in French-Canadian HHH patients and encodes an unstable protein; E180K, which encodes a stable, properly targeted protein that is inactive; and a 13q14 microdeletion. Our results show that ORNT1 encodes the mitochondrial ornithine transporter involved in UC function and is defective in HHH syndrome.
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Affiliation(s)
- J A Camacho
- Institute for Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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35
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del Arco A, Satrústegui J. Molecular cloning of Aralar, a new member of the mitochondrial carrier superfamily that binds calcium and is present in human muscle and brain. J Biol Chem 1998; 273:23327-34. [PMID: 9722566 DOI: 10.1074/jbc.273.36.23327] [Citation(s) in RCA: 142] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have identified a new calcium-dependent subfamily of mitochondrial carrier proteins with members in Saccharomyces cerevisiae, Caenorhabditis elegans, and various mammalian species. The members of this subfamily have a bipartite structure: a carboxyl-terminal half with the characteristic features of the mitochondrial solute carrier superfamily and an amino-terminal extension harboring various EF-hand domains. A member of this subfamily (that we have termed Aralar) was cloned from a human heart cDNA library. The corresponding cDNA comprises an open reading frame of 2037 base pairs encoding a polypeptide of 678 amino acids. The carboxyl-terminal half of Aralar (amino acids 321-678) has high similarity with the oxoglutarate, citrate, and adenine nucleotide carriers (28-29% identity), whereas the amino-terminal half (amino acids 1-320) contains three canonical EF-hands. Aralar amino-terminal half was shown to bind calcium by 45Ca2+ overlay and calcium-dependent mobility shift assays. The subcellular localization of the protein in COS cells transfected with Aralar was exclusively mitochondrial. Antibodies against Aralar amino-terminal fusion protein recognized a 70-kDa protein in brain mitochondrial fractions. Northern blot analysis showed that the protein was expressed in heart, brain, and skeletal muscle. The domain structure, mitochondrial localization, and presence in excitable tissues suggests a possible function of Aralar as calcium-dependent mitochondrial solute carrier.
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Affiliation(s)
- A del Arco
- Departamento de Biologia Molecular, Centro de Biologia Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, 28049-Madrid, Spain
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Nelson DR, Felix CM, Swanson JM. Highly conserved charge-pair networks in the mitochondrial carrier family. J Mol Biol 1998; 277:285-308. [PMID: 9514746 DOI: 10.1006/jmbi.1997.1594] [Citation(s) in RCA: 157] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Selection for regain-of-function mutations in the yeast ADP/ATP carrier AAC2 has revealed an unexpected series of charge-pairs. Four of the six amino acids involved are found in the mitochondrial energy transfer motifs used to define this family of proteins. As such, the results found with the ADP/ATP carrier may apply to the family as a whole. Mitochondrial carriers are built from three homologous domains, each with the conserved motif PX(D,E)XX(K,R). Neutralization of the conserved positive charges at K48, R152 or R252 in these motifs results in respiration defective yeast. Neutralization of the negative charges at D149 and D249 also make respiration defective yeast, though E45G or E45Q mutants are able to grow on glycerol. Regain of function occurs when a complementary charge is lost from another site in the molecule. This phenomenon has been observed independently eight times and thus is strong evidence for charge-pairs existing between the affected residues. Five different charge-pairs have been detected in the yeast AAC2 by this method and three more can be predicted based on homology between the domains. The highly conserved charge-pairs occurring within or between the three mitochondrial energy transfer signatures seem to be a critical feature of mitochondrial carrier structure, independent of the substrates transported. Conformational switching between alternative charge-pairs may constitute part of the basis for transport.
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Affiliation(s)
- D R Nelson
- Department of Biochemistry, The University of Tennessee, Memphis, TN 38163, USA
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