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Weiher H, Pircher H, Jansen-Dürr P, Hegenbarth S, Knolle P, Grunau S, Vapola M, Hiltunen JK, Zwacka RM, Schmelzer E, Reumann K, Will H. A monoclonal antibody raised against bacterially expressed MPV17 sequences shows peroxisomal, endosomal and lysosomal localisation in U2OS cells. BMC Res Notes 2016; 9:128. [PMID: 26921094 PMCID: PMC4769525 DOI: 10.1186/s13104-016-1939-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 02/16/2016] [Indexed: 12/02/2022] Open
Abstract
Recessive mutations in the MPV17 gene cause mitochondrial DNA depletion syndrome, a fatal infantile genetic liver disease in humans. Loss of function in mice leads to glomerulosclerosis and sensineural deafness accompanied with mitochondrial DNA depletion. Mutations in the yeast homolog Sym1, and in the zebra fish homolog tra cause interesting, but not obviously related phenotypes, although the human gene can complement the yeast Sym1 mutation. The MPV17 protein is a hydrophobic membrane protein of 176 amino acids and unknown function. Initially localised in murine peroxisomes, it was later reported to be a mitochondrial inner membrane protein in humans and in yeast. To resolve this contradiction we tested two new mouse monoclonal antibodies directed against the human MPV17 protein in Western blots and immunohistochemistry on human U2OS cells. One of these monoclonal antibodies showed specific reactivity to a protein of 20 kD absent in MPV17 negative mouse cells. Immunofluorescence studies revealed colocalisation with peroxisomal, endosomal and lysosomal markers, but not with mitochondria. This data reveal a novel connection between a possible peroxisomal/endosomal/lysosomal function and mitochondrial DNA depletion.
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Affiliation(s)
- Hans Weiher
- Heinrich-Pette-Institute, Leibniz-Institute for Experimental Virology, Martinistrasse 52, 20251, Hamburg, Germany. .,Bonn-Rhein-Sieg University, von Liebig Strasse 20, 53359, Rheinbach, Germany.
| | - Haymo Pircher
- Institute for Biomedical Aging Research, University of Innsbruck, Rennweg 10, 6020, Innsbruck, Austria.
| | - Pidder Jansen-Dürr
- Institute for Biomedical Aging Research, University of Innsbruck, Rennweg 10, 6020, Innsbruck, Austria.
| | - Silke Hegenbarth
- Institutes of Molecular Medicine and Experimental Immunology, Universität Bonn, 53105, Bonn, Germany.
| | - Percy Knolle
- Institutes of Molecular Medicine and Experimental Immunology, Universität Bonn, 53105, Bonn, Germany.
| | - Silke Grunau
- Department of Biochemistry, Biocenter Oulu, University of Oulu, FI-90014, Oulu, Finland.
| | - Miia Vapola
- Department of Biochemistry, Biocenter Oulu, University of Oulu, FI-90014, Oulu, Finland.
| | - J Kalervo Hiltunen
- Department of Biochemistry, Biocenter Oulu, University of Oulu, FI-90014, Oulu, Finland.
| | - Ralf M Zwacka
- School of Biological Sciences, University of Essex, Colchester, CO4 3SQ, UK.
| | - Elmon Schmelzer
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829, Cologne, Germany.
| | - Kerstin Reumann
- Heinrich-Pette-Institute, Leibniz-Institute for Experimental Virology, Martinistrasse 52, 20251, Hamburg, Germany.
| | - Hans Will
- Heinrich-Pette-Institute, Leibniz-Institute for Experimental Virology, Martinistrasse 52, 20251, Hamburg, Germany.
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2
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Dalla Rosa I, Durigon R, Pearce SF, Rorbach J, Hirst EMA, Vidoni S, Reyes A, Brea-Calvo G, Minczuk M, Woellhaf MW, Herrmann JM, Huynen MA, Holt IJ, Spinazzola A. MPV17L2 is required for ribosome assembly in mitochondria. Nucleic Acids Res 2014; 42:8500-15. [PMID: 24948607 PMCID: PMC4117752 DOI: 10.1093/nar/gku513] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
MPV17 is a mitochondrial protein of unknown function, and mutations in MPV17 are associated with mitochondrial deoxyribonucleic acid (DNA) maintenance disorders. Here we investigated its most similar relative, MPV17L2, which is also annotated as a mitochondrial protein. Mitochondrial fractionation analyses demonstrate MPV17L2 is an integral inner membrane protein, like MPV17. However, unlike MPV17, MPV17L2 is dependent on mitochondrial DNA, as it is absent from ρ(0) cells, and co-sediments on sucrose gradients with the large subunit of the mitochondrial ribosome and the monosome. Gene silencing of MPV17L2 results in marked decreases in the monosome and both subunits of the mitochondrial ribosome, leading to impaired protein synthesis in the mitochondria. Depletion of MPV17L2 also induces mitochondrial DNA aggregation. The DNA and ribosome phenotypes are linked, as in the absence of MPV17L2 proteins of the small subunit of the mitochondrial ribosome are trapped in the enlarged nucleoids, in contrast to a component of the large subunit. These findings suggest MPV17L2 contributes to the biogenesis of the mitochondrial ribosome, uniting the two subunits to create the translationally competent monosome, and provide evidence that assembly of the small subunit of the mitochondrial ribosome occurs at the nucleoid.
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Affiliation(s)
- Ilaria Dalla Rosa
- MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Romina Durigon
- MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Sarah F Pearce
- MRC Mitochondrial Biology Unit, Wellcome Trust-MRC Building, Hills Road, Cambridge CB2 0XY, UK
| | - Joanna Rorbach
- MRC Mitochondrial Biology Unit, Wellcome Trust-MRC Building, Hills Road, Cambridge CB2 0XY, UK
| | | | - Sara Vidoni
- MRC Mitochondrial Biology Unit, Wellcome Trust-MRC Building, Hills Road, Cambridge CB2 0XY, UK
| | - Aurelio Reyes
- MRC Mitochondrial Biology Unit, Wellcome Trust-MRC Building, Hills Road, Cambridge CB2 0XY, UK
| | - Gloria Brea-Calvo
- MRC Mitochondrial Biology Unit, Wellcome Trust-MRC Building, Hills Road, Cambridge CB2 0XY, UK
| | - Michal Minczuk
- MRC Mitochondrial Biology Unit, Wellcome Trust-MRC Building, Hills Road, Cambridge CB2 0XY, UK
| | - Michael W Woellhaf
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | | | - Martijn A Huynen
- Centre for Molecular and Biomolecular Informatics, Radboud University Medical Centre, Geert Grooteplein Zuid 26-28, 6525 GA Nijmegen, Netherlands
| | - Ian J Holt
- MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
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Chau BN, Xin C, Hartner J, Ren S, Castano AP, Linn G, Li J, Tran PT, Kaimal V, Huang X, Chang AN, Li S, Kalra A, Grafals M, Portilla D, MacKenna DA, Orkin SH, Duffield JS. MicroRNA-21 promotes fibrosis of the kidney by silencing metabolic pathways. Sci Transl Med 2012; 4:121ra18. [PMID: 22344686 DOI: 10.1126/scitranslmed.3003205] [Citation(s) in RCA: 413] [Impact Index Per Article: 34.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Scarring of the kidney is a major public health concern, directly promoting loss of kidney function. To understand the role of microRNA (miRNA) in the progression of kidney scarring in response to injury, we investigated changes in miRNA expression in two kidney fibrosis models and identified 24 commonly up-regulated miRNAs. Among them, miR-21 was highly elevated in both animal models and in human transplanted kidneys with nephropathy. Deletion of miR-21 in mice resulted in no overt abnormality. However, miR-21(-/-) mice suffered far less interstitial fibrosis in response to kidney injury, a phenotype duplicated in wild-type mice treated with anti-miR-21 oligonucleotides. Global derepression of miR-21 target mRNAs was readily detectable in miR-21(-/-) kidneys after injury. Analysis of gene expression profiles up-regulated in the absence of miR-21 identified groups of genes involved in metabolic pathways, including the lipid metabolism pathway regulated by peroxisome proliferator-activated receptor-α (Pparα), a direct miR-21 target. Overexpression of Pparα prevented ureteral obstruction-induced injury and fibrosis. Pparα deficiency abrogated the antifibrotic effect of anti-miR-21 oligonucleotides. miR-21 also regulated the redox metabolic pathway. The mitochondrial inhibitor of reactive oxygen species generation Mpv17l was repressed by miR-21, correlating closely with enhanced oxidative kidney damage. These studies demonstrate that miR-21 contributes to fibrogenesis and epithelial injury in the kidney in two mouse models and is a candidate target for antifibrotic therapies.
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4
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Missing mitochondrial Mpv17 gene function induces tissue-specific cell-death pathway in the degenerating inner ear. Cell Tissue Res 2012; 347:343-56. [PMID: 22322422 DOI: 10.1007/s00441-012-1326-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Accepted: 01/11/2012] [Indexed: 12/11/2022]
Abstract
The Mpv17 gene encodes a mitochondrial inner-membrane protein that has been implicated in the metabolism of reactive oxygen species. The loss of function in Mpv17-/- mice leads to early sensorineural deafness associated with severe inner ear degeneration and late onset of kidney failure. The present study demonstrates that the onset of the degeneration of the cochlear neuroepithelia is related to the onset of auditory function and appears to be first restricted to the outer hair cells (OHC), which subsequently undergo rapid degeneration. At the age of 18 days, the OHC lateral membrane degenerates and extensive vacuolization of the cytoplasm is followed by lysis of the OHCs. Such degenerative processes have been seen for the first time in relation to auditory dysfunction. The structural degeneration pattern of the OHC appears to be similar to the described paraptotic processes (an alternative form of programmed cell death) discussed in the literature as a cause of cytoplasmic neurodegeneration. In contrast, the melanocyte-like intermediate cells that are of neural crest origin and that are located in the stria vascularis, undergo apoptosis, as documented ultrastructurally. A lack of Mpv17 protein function in mitochondria thus seems to initiate tissue-specific cell-death pathways resulting in the pathology seen during the degeneration process.
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5
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Overexpression and purification of rat peroxisomal membrane protein 22, PMP22, in Pichia pastoris. Protein Expr Purif 2009; 64:47-54. [DOI: 10.1016/j.pep.2008.10.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2008] [Revised: 10/09/2008] [Accepted: 10/10/2008] [Indexed: 11/19/2022]
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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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7
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Van Ael E, Fransen M. Targeting signals in peroxisomal membrane proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:1629-38. [PMID: 17020786 DOI: 10.1016/j.bbamcr.2006.08.020] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2006] [Revised: 08/17/2006] [Accepted: 08/18/2006] [Indexed: 10/24/2022]
Abstract
Peroxisomal membrane proteins (PMPs) are encoded by the nuclear genome and translated on cytoplasmic ribosomes. Newly synthesized PMPs can be targeted directly from the cytoplasm to peroxisomes or travel to peroxisomes via the endoplasmic reticulum (ER). The mechanisms responsible for the targeting of these proteins to the peroxisomal membrane are still rather poorly understood. However, it is clear that the trafficking of PMPs to peroxisomes depends on the presence of cis-acting targeting signals, called mPTSs. These mPTSs show great variability both in the identity and number of requisite residues. An emerging view is that mPTSs consist of at least two functionally distinct domains: a targeting element, which directs the newly synthesized PMP from the cytoplasm to its target membrane, and a membrane-anchoring sequence, which is required for the permanent insertion of the protein into the peroxisomal membrane. In this review, we summarize our knowledge of the mPTSs currently identified.
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Affiliation(s)
- Elke Van Ael
- Katholieke Universiteit Leuven, Faculty of Medicine, Department of Molecular Cell Biology, Division of Pharmacology, Campus Gasthuisberg, Herestraat 49 bus 601, 3000 Leuven, Belgium
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8
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Nestler M, Martin U, Hortschansky P, Saluz HP, Henke A, Munder T. The zinc containing pro-apoptotic protein siva interacts with the peroxisomal membrane protein pmp22. Mol Cell Biochem 2006; 287:147-55. [PMID: 16683188 DOI: 10.1007/s11010-005-9082-6] [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: 09/14/2005] [Accepted: 11/16/2005] [Indexed: 10/24/2022]
Abstract
Host answers to pathogen attacks define the course of pathogenic events and decide about the fate of the host organism. Infection with coxsackievirus B3 (CVB3) can induce severe myocarditis and pancreatitis. The interplay between host factors and virus components is crucial for the fate of the infected host. As we have shown before, expression of the pro-apoptotic host protein Siva is significantly increased after CVB3 infection, and infected cells are removed by programmed cell death. Analysis of Siva expressed in Escherichia coli revealed that this protein binds three zinc ions, suggesting a rather complex three-dimensional structure. By screening a human heart cDNA library we found a new interaction partner of Siva. The peroxisomal membrane protein PMP22 may be involved in the host response against CVB3. Previous investigations showed that Siva interacts with the cytoplasmic C-terminus of CD27, a member of the tumor necrosis factor receptor group, and transmits an apoptotic signal. With the help of directed two-hybrid assays we determined the N-terminal part of Siva as the binding region for CD27.
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Affiliation(s)
- Matthias Nestler
- Department of Cell and Molecular Biology, Leibniz-Institute for Natural Product Research and Infection Biology--Hans-Knöll-Institute, Jena, Germany.
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Meyer zum Gottesberge AM, Felix H. Abnormal basement membrane in the inner ear and the kidney of the Mpv17-/- mouse strain: ultrastructural and immunohistochemical investigations. Histochem Cell Biol 2005; 124:507-16. [PMID: 16041630 DOI: 10.1007/s00418-005-0027-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/04/2005] [Indexed: 11/30/2022]
Abstract
The loss of the function of the peroxisomal Mpv17-protein and associated imbalanced radical oxygen species (ROS) homeostasis leads to an early onset of focal segmental glomerulosclerosis and sensorineural deafness associated with severe degeneration of cochlear structures. An excessive enlargement of basal laminae of the stria vascularis capillaries and glomeruli indicates numerous changes in their molecular composition. The basement membrane (BM) of the glomeruli and the stria vascularis are simultaneously affected in early stages of the disease and the lamination, splitting of the membrane and formation of the "basket weaving" seen at the onset of the disease in the kidney are similar to the ultrastructural alterations characteristic for Alporta9s syndrome. The progressive alteration of the BMs is accompanied by irregularity in the distribution of the collagen IV subunits and by an accumulation of the laminin B2(gamma1) in the inner ear and B(beta1) in the kidney. Since Mpv17 protein contributes to ROS homeostasis, further studies are necessary to elucidate downstream signaling molecules activated by ROS. These studies explain the cellular responses to missing Mpv17-protein, such as accumulation of the extracellular matrix, degeneration, and apoptosis in the inner ear.
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Affiliation(s)
- Angela M Meyer zum Gottesberge
- Research Laboratory, Department of Otorhinolaryngology, University of Düsseldorf, Moorenstr, 5, 40225, Dusseldorf, Germany,
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Iida R, Yasuda T, Tsubota E, Takatsuka H, Masuyama M, Matsuki T, Kishi K. A novel alternative spliced Mpv17-like protein isoform localizes in cytosol and is expressed in a kidney- and adult-specific manner. Exp Cell Res 2005; 302:22-30. [PMID: 15541722 DOI: 10.1016/j.yexcr.2004.08.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2004] [Revised: 08/17/2004] [Indexed: 01/22/2023]
Abstract
Mpv17-like protein (M-LP) has been identified as a new protein that shows high sequence homology with Mpv17 protein, a peroxisomal membrane protein involved in the development of early onset glomerulosclerosis. We previously showed that the originally identified M-LP isoform, designated M-LPL, is, like Mpv17, localized in peroxisomes, and that transfection with M-LPL up-regulates expression of the manganese superoxide dismutase (SOD2) gene [R. Iida, T. Yasuda, E. Tsubota, H. Takatsuka, M. Masuyama, T. Matsuki, K. Kishi, M-LP, Mpv17-like protein, has a peroxisomal membrane targeting signal comprising a transmembrane domain and a positively charged loop and up-regulates expression of the manganese superoxide dismutase gene. J. Biol. Chem. 278 (2003) 6301-6306.]. We report here the identification of a novel alternative splicing product of the M-LP gene, designated M-LPS. A comparison of the genomic sequence with the cDNA sequences and an analysis of 5'-flanking regions revealed that the two isoforms are generated by alternative usage of two promoters. M-LPS consists of the C-terminal half of M-LPL (90 amino acids) and therefore lacks the peroxisome targeting signal of membrane protein that exists near the N-terminus of M-LPL. Expression of green fluorescent protein-tagged M-LPS in COS-7 cells demonstrated that M-LPS localizes in the cytosol. In mice, M-LPS is expressed exclusively in kidneys after the age of 6 weeks. Moreover, quantitative real-time PCR analysis revealed that transfection with M-LPS up-regulates expression of the SOD2 gene and down-regulates expression of the cellular glutathione peroxidase (Gpx1) and plasma glutathione peroxidase (Gpx3) genes. Taken together, these results suggest different functional attributes of the two M-LP isoforms during aging and development.
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Affiliation(s)
- Reiko Iida
- Department of Forensic Medicine, Faculty of Medical Sciences, University of Fukui, Fukui 910-1193, Japan.
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Otte DM, Schwaab U, Lüers GH. The Pxmp2 and PoleI genes are linked by a bidirectional promoter in an evolutionary conserved fashion. Gene 2003; 313:119-26. [PMID: 12957383 DOI: 10.1016/s0378-1119(03)00667-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Pxmp2 is the most abundant peroxisomal membrane protein in higher eukaryotes. Its expression is tissue-specific with highest levels of expression in liver, kidney and heart tissue. We have analysed the 5'-flanking genomic region of the murine Pxmp2 gene and we found, that the first exon of the gene encoding the DNA polymerase epsilon (PoleI) was localized adjacent to the first exon of the Pxmp2 gene in head to head orientation. Both genes were separated by only 393 bp containing a CpG island with numerous binding sites for Sp1. A TATA box, however, was lacking. Northern blot analysis revealed that both genes were expressed differently, indicating that their expression was regulated independently. We have analysed the promoter activity of the small genomic fragment separating the Pxmp2 and PoleI genes using luciferase as a reporter molecule in transient transfection assays. The small genomic fragment was a functional promoter, controlling gene expression regardless of its orientation. Promoter activity was 60-70% compared with the activity of the strong CMV promoter. The Pxmp2 and PoleI genes were also linked on the human and rat genome. Furthermore, the sequence of the intergenic fragment was highly conserved among these species. Thus, the small intergenic fragment is probably the common basic element of two independently regulated promoters.
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Affiliation(s)
- David M Otte
- Institute for Anatomy, University of Bonn, Bonn, Germany
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12
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Brosius U, Dehmel T, Gärtner J. Two different targeting signals direct human peroxisomal membrane protein 22 to peroxisomes. J Biol Chem 2002; 277:774-84. [PMID: 11590176 DOI: 10.1074/jbc.m108155200] [Citation(s) in RCA: 51] [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
The 22-kDa peroxisomal membrane protein (PMP22) is a major component of peroxisomal membranes in mammals. Although its precise role in peroxisome function is poorly understood, it seems to be involved in pore forming activity and may contribute to the unspecific permeability of the organelle membrane. PMP22 is synthesized on free cytosolic ribosomes and then directed to the peroxisome membrane by specific targeting information. Previous studies in rats revealed that PMP22 contains one distinct peroxisomal membrane targeting signal in the amino-terminal cytoplasmic tail. We cloned and characterized the targeting signal of human PMP22 and compared it with the already described characteristics of the corresponding rat protein. Amino acid sequence alignment of rat and human protein revealed 77% identity including a high conservation of several protein motifs. We expressed various deletion constructs of PMP22 in fusion with the green fluorescent protein in COS-7 cells and determined their intracellular localization. In contrast to previous studies on rat PMP22 and most other peroxisomal membrane proteins, we showed that human as well as rat PMP22 contains two distinct and nonoverlapping peroxisomal membrane targeting signals, one in the amino-terminal and the other in the carboxyl-terminal protein region. They consist of two transmembrane domains and adjacent protein loops with almost identical basic clusters. Both of these peroxisomal targeting regions interact with PEX19, a factor required for peroxisome membrane synthesis. In addition, we observed that fusing the green fluorescent protein immediately adjacent to the targeting region completely abolishes targeting function and mislocalizes PMP22 to the cytosol.
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Affiliation(s)
- Ute Brosius
- Department of Pediatrics, Heinrich Heine University, Düsseldorf D-40225, Germany
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Lüers GH, Otte DM, Subramani S, Franz T. Genomic organization, chromosomal localization and tissue specific expression of the murine Pxmp2 gene encoding the 22 kDa peroxisomal membrane protein (Pmp22). Gene 2001; 272:45-50. [PMID: 11470509 DOI: 10.1016/s0378-1119(01)00531-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Peroxisomes are subcellular organelles with important functions in lipid metabolism that are found in virtually all eucaryotic cells. The peroxisomal membrane contains a number of integral and peripheral membrane proteins involved in the import of peroxisomal matrix proteins and the transport of metabolites across the membrane. The most abundant peroxisomal membrane protein (Pmp) in rat peroxisomes is Pmp22, a 22 kDa protein of unknown function that is encoded by the Pxmp2 gene. To investigate the function of the Pxmp2 gene, we have initiated mouse knockout studies. The expression level of the Pxmp2 mRNA in mice was investigated by Northern blot analysis. Pxmp2 RNA was shown to be differentially expressed with highest expression levels in liver, kidney and in heart tissue. Comparison with other peroxisomal marker genes revealed that the expression of Pxmp2, Pmp70 (Pxmp1) and catalase was regulated independently. Using 5' and 3' RACE we have cloned the full-length cDNA of murine Pxmp2 which comprises 863 nucleotides and have isolated a genomic clone containing the entire murine Pxmp2. We have analyzed the complete intron/exon structure of the Pxmp2 gene which contains five exons spanning about 11 kb on the genomic clone. All intron/exon splice junctions conform to the GT/AG rule. Sequence analysis of the Pxmp2 5' flanking region revealed that it was devoid of a TATA box, but characteristic promoter elements were identified within 250 base pairs upstream of the transcriptional start site. Using a mouse/hamster radiation hybrid panel, Pxmp2 was localized on mouse chromosome 5 at 59 cM.
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Affiliation(s)
- G H Lüers
- University of Bonn, Institute for Anatomy, Nussallee 10, D-53115 Bonn, Germany.
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Corpas FJ, Sandalio LM, Brown MJ, del Río LA, Trelease RN. Identification of porin-like polypeptide(s) in the boundary membrane of oilseed glyoxysomes. PLANT & CELL PHYSIOLOGY 2000; 41:1218-28. [PMID: 11092906 DOI: 10.1093/pcp/pcd054] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
A 36-kDa polypeptide of unknown function was identified by us in the boundary membrane fraction of cucumber seedling glyoxysomes. Evidence is presented in this study that this 36-kDa polypeptide is a glyoxysomal membrane porin. A sequence of 24 amino acid residues derived from a CNBr-cleaved fragment of the 36-kDa polypeptide revealed 72% to 95% identities with sequences in mitochondrial or non-green plastid porins of several different plant species. Immunological evidence indicated that the 36-kDa (and possibly a 34-kDa polypeptide) was a porin(s). Antiserum raised against a potato tuber mitochondrial porin recognized on immunoblots 34-kDa and 36-kDa polypeptides in detergent-solubilized membrane fractions of cucumber seedling glyoxysomes and mitochondria, and in similar glyoxysomal fractions of cotton, castor bean, and sunflower seedlings. The 36-kDa polypeptide seems to be a constitutive component because it was detected also in membrane protein fractions derived from cucumber leaf-type peroxisomes. Compelling evidence that one or both of these polypeptides were authentic glyoxysomal membrane porins was obtained from electron microscopic immunogold analyses. Antiporin IgGs recognized antigen(s) in outer membranes of glyoxysomes and mitochondria. Taken together, the data indicate that membranes of cucumber (and other oilseed) glyoxysomes, leaf-type peroxisomes, and mitochondria possess similar molecular mass porin polypeptide(s) (34 and 36 kDa) with overlapping immunological and amino acid sequence similarities.
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Affiliation(s)
- F J Corpas
- Departamento de Bioquímica, Biología Celular y Molecular de Plantas, Estación Experimental del Zaidín, CSIC, Apdo. 419, E-18080 Granada, Spain
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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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16
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Pause B, Saffrich R, Hunziker A, Ansorge W, Just WW. Targeting of the 22 kDa integral peroxisomal membrane protein. FEBS Lett 2000; 471:23-8. [PMID: 10760506 DOI: 10.1016/s0014-5793(00)01332-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Investigating targeting of the 22 kDa peroxisomal membrane protein (Pmp22p) to the peroxisomal membrane we have confined the targeting signal to amino acid residues 16-37 located in the N-terminal cytoplasmic tail. Comparison of Pmp22p orthologous sequences revealed a conserved motif Y3xL3xP3x(KQN) which might represent the core of this targeting signal not found so far in other Pmps. Fusion of the Pmp22p N-terminal tail to the C-terminal portion of Pmp22p which per se is not targeted to peroxisomes, conveys peroxisomal targeting. These data suggest that Pmp22p is targeted to peroxisomes by a new membrane targeting signal which is necessary and sufficient to target a polypeptide containing two transmembrane spans to peroxisomes.
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Affiliation(s)
- B Pause
- Biochemie-Zentrum Heidelberg (BZH), Universität Heidelberg, Im Neuenheimer Feld 328, D-69120, Heidelberg, Germany
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17
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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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18
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Tugal HB, Pool M, Baker A. Arabidopsis 22-kilodalton peroxisomal membrane protein. Nucleotide sequence analysis and biochemical characterization. PLANT PHYSIOLOGY 1999; 120:309-320. [PMID: 10318708 PMCID: PMC59263 DOI: 10.1104/pp.120.1.309] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/1998] [Accepted: 01/18/1999] [Indexed: 05/23/2023]
Abstract
We sequenced and characterized PMP22 (22-kD peroxisomal membrane protein) from Arabidopsis, which shares 28% to 30% amino acid identity and 55% to 57% similarity to two related mammalian peroxisomal membrane proteins, PMP22 and Mpv17. Subcellular fractionation studies confirmed that the Arabidopsis PMP22 is a genuine peroxisomal membrane protein. Biochemical analyses established that the Arabidopsis PMP22 is an integral membrane protein that is completely embedded in the lipid bilayer. In vitro import assays demonstrated that the protein is inserted into the membrane posttranslationally in the absence of ATP, but that ATP stimulates the assembly into the native state. Arabidopsis PMP22 is expressed in all organs of the mature plant and in tissue-cultured cells. Expression of PMP22 is not associated with a specific peroxisome type, as it is detected in seeds and throughout postgerminative growth as cotyledon peroxisomes undergo conversion from glyoxysomes to leaf-type peroxisomes. Although PMP22 shows increased accumulation during the growth of young seedlings, its expression is not stimulated by light.
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Affiliation(s)
- H B Tugal
- Centre for Plant Sciences, Leeds Institute for Plant Biotechnology and Agriculture, University of Leeds, Leeds LS2 9JT, United Kingdom
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19
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Passreiter M, Anton M, Lay D, Frank R, Harter C, Wieland FT, Gorgas K, Just WW. Peroxisome biogenesis: involvement of ARF and coatomer. J Biophys Biochem Cytol 1998; 141:373-83. [PMID: 9548716 PMCID: PMC2148451 DOI: 10.1083/jcb.141.2.373] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Peroxisomal membrane protein (Pmp)26p (RnPex11p), a major constituent of induced rat liver peroxisomal membrane, was found to contain a COOH-terminal, cytoplasmically exposed consensus dilysine motif with the potential to bind coatomer. Biochemical as well as immunocytochemical evidence is presented showing that peroxisomes incubated with preparations of bovine brain or rat liver cytosol recruit ADP-ribosylation factor (ARF) and coatomer in a strictly guanosine 5'-O-(3-thiotriphosphate)-dependent manner. Consistent with this observation, ldlF cells expressing a temperature-sensitive mutant version of the epsilon-subunit of coatomer exhibit elongated tubular peroxisomes possibly due to impaired vesiculation at the nonpermissive temperature. Since overexpression of Pex11p in Chinese hamster ovary wild-type cells causes proliferation of peroxisomes, these data suggest that Pex11p plays an important role in peroxisome biogenesis by supporting ARF- and coatomer-dependent vesiculation of the organelles.
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Affiliation(s)
- M Passreiter
- Biochemie-Zentrum, Universität Heidelberg, D-69120 Heidelberg, Germany
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20
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Abstract
Peroxisomes were long believed to play only a minor role in cellular metabolism but it is now clear that they catalyze a number of important functions. The importance of peroxisomes in humans is stressed by the existence of a group of genetic diseases in man in which one or more peroxisomal functions are impaired. Most of the functions known to take place in peroxisomes have to do with lipids. Indeed, peroxisomes are capable of 1. fatty acid beta-oxidation 2. fatty acid alpha-oxidation 3. synthesis of cholesterol and other isoprenoids 4. ether-phospholipid synthesis and 5. biosynthesis of polyunsaturated fatty acids. In Chapters 2-6 we will discuss the functional organization and enzymology of these pathways in detail. Furthermore, attention is paid to the permeability properties of peroxisomes with special emphasis on recent studies which suggest that peroxisomes are closed structures containing specific membrane proteins for transport of metabolites. Finally, the disorders of peroxisomal lipid metabolism will be discussed.
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Affiliation(s)
- R J Wanders
- Department of Clinical Chemistry, University of Amsterdam, The Netherlands
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Affiliation(s)
- P Rehling
- Institut für Physiologische Chemie, Ruhr-Universität Bochum, Germany
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Affiliation(s)
- W W Just
- Institut für Biochemie I, Universität Heidelberg, Germany
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23
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Elgersma Y, Tabak HF. Proteins involved in peroxisome biogenesis and functioning. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1286:269-83. [PMID: 8982286 DOI: 10.1016/s0304-4157(96)00012-3] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Y Elgersma
- Department of Biochemistry, University of Amsterdam, The Netherlands
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24
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Imanaka T, Shiina Y, Takano T, Hashimoto T, Osumi T. Insertion of the 70-kDa peroxisomal membrane protein into peroxisomal membranes in vivo and in vitro. J Biol Chem 1996; 271:3706-13. [PMID: 8631984 DOI: 10.1074/jbc.271.7.3706] [Citation(s) in RCA: 107] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Biosynthesis and intracellular transport of 70-kda peroxisomal membrane protein (pmp70) has been studied in rat hepatoma, h-4-ii-e cells. Pulse-chase analysis showed that a newly synthesized 35S-PMP70 first appeared in the cytosolic fraction and was then transported into the peroxisomal fraction. The half-life of 35S-PMP70 in the cytosolic fraction was approximately 3 min. Integration of 35S-PMP70 into membranes occurred in the peroxisomal fraction and was completed within 30 min. No proteolytic processing of 35S-PMP70 was observed. An in vitro import system was reconstituted to characterize the insertion mechanism of PMP70 into peroxisomes. Peroxisomes isolated from rat liver were incubated at 26 degrees C with [35S]methionine-labeled in vitro translation products of PMP70 mRNA in the presence of the cytosolic fraction. The peroxisomes were reisolated and insertion of 35S-PMP70 into the membrane was analyzed using a Na2CO3 procedure. The binding and insertion of 35S-PMP70 were dependent on temperature and incubation time and was specific for peroxisomes. Pretreatment of peroxisomes with trypsin and chymotrypsin almost abolished the binding and insertion of 35S-PMP70. The translation products contained several truncated 35S-PMP70s. The NH2 terminally truncated 35S-PMP70s, with a molecular mass greater than 50 kDa, bound to and inserted into peroxisomal membranes, whereas truncated 35S-PMP70s smaller than 45 kDa did not. These results suggest that PMP70 is post-translationally transported to peroxisomes without processing and inserted into peroxisomal membranes by a specific mechanism in which a proteinaceous receptor and a certain internal sequence of PMP70 are involved.
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Affiliation(s)
- T Imanaka
- Department of Microbiology and Molecular Pathology, Faculty of Pharmaceutical Sciences, Teikyo University, Sagamiko, Kanagawa 199-01, Japan
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25
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Reumann S, Maier E, Benz R, Heldt HW. The membrane of leaf peroxisomes contains a porin-like channel. J Biol Chem 1995; 270:17559-65. [PMID: 7542242 DOI: 10.1074/jbc.270.29.17559] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Spinach leaf peroxisomes were purified by Percoll density gradient centrifugation. After several freeze-thaw cycles, the peroxisomal membranes were separated from the matrix enzymes by sucrose density gradient centrifugation. The purity of the peroxisomal membranes was checked by measuring the activities of marker enzymes and by using antibodies. Lipid bilayer membrane experiments with the purified peroxisomal membranes, solubilized with a detergent, demonstrated that the membranes contain a channel-forming component, which may represent the major permeability pathway of these membranes. Control experiments with membranes of other cell organelles showed that the peroxisomal channel was not caused by the contamination of the peroxisomes with mitochondria or chloroplasts. The peroxisomal channel had a comparatively small single channel conductance of 350 pS in 1 M KCl as compared with channels from other cell organelles. The channel is slightly anion selective, which is in accordance with its physiological function. The single channel conductance was found to be only moderately dependent on the salt concentration in the aqueous phase. This may be explained by the presence of positive point net charges in or near the channel or by the presence of a saturable binding site inside the channel. The possible role of the channel in peroxisomal metabolism is discussed.
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Affiliation(s)
- S Reumann
- Institut für Biochemie der Pflanze, Universität Göttingen, Federal Republic of Germany
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26
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Erdmann R, Blobel G. Giant peroxisomes in oleic acid-induced Saccharomyces cerevisiae lacking the peroxisomal membrane protein Pmp27p. J Biophys Biochem Cytol 1995; 128:509-23. [PMID: 7860627 PMCID: PMC2199900 DOI: 10.1083/jcb.128.4.509] [Citation(s) in RCA: 240] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
We have purified peroxisomal membranes from Saccharomyces cerevisiae after induction of peroxisomes in oleic acid-containing media. About 30 distinct proteins could be discerned among the HPLC- and SDS-PAGE-separated proteins of the high salt-extracted peroxisomal membranes. The most abundant of these, Pmp27p, was purified and the corresponding gene PMP27 was cloned and sequenced. Its primary structure is 32% identical to PMP31 and PMP32 of the yeast Candida biodinii (Moreno, M., R. Lark, K. L. Campbell, and M. J. Goodman. 1994. Yeast. 10:1447-1457). Immunoelectron microscopic localization of Pmp27p showed labeling of the peroxisomal membrane, but also of matrix-less and matrix containing tubular membranes nearby. Electronmicroscopical data suggest that some of these tubular extensions might interconnect peroxisomes to form a peroxisomal reticulum. Cells with a disrupted PMP27 gene (delta pmp27) still grew well on glucose or ethanol, but they failed to grow on oleate although peroxisomes were still induced by transfer to oleate-containing media. The induced peroxisomes of delta pmp27 cells were fewer but considerably larger than those of wild-type cells, suggesting that Pmp27p may be involved in parceling of peroxisomes into regular quanta. delta pmp27 cells cultured in oleate-containing media form multiple buds, of which virtually all are peroxisome deficient. The growth defect of delta pmp27 cells on oleic acid appears to result from the inability to segregate the giant peroxisomes to daughter cells.
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Affiliation(s)
- R Erdmann
- Laboratory of Cell Biology, Howard Hughes Medical Institute, Rockefeller University, New York 10021
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27
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Moreno M, Lark R, Campbell KL, Goodman JM. The peroxisomal membrane proteins of Candida boidinii: gene isolation and expression. Yeast 1994; 10:1447-57. [PMID: 7871884 DOI: 10.1002/yea.320101108] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Candida boidinii is a methylotrophic yeast in which several growth substrates can cause vigorous peroxisomal proliferation. While such diverse substrates as methanol, oleic acid and D-alanine induce different peroxisomal metabolic pathways, membranes seem to contain common abundant peroxisomal membrane proteins (PMPs). These proteins have been termed PMP31, PMP32 and PMP47. The gene encoding PMP47 has been previously cloned and analysed. We now report the isolation of a second PMP47 gene (or allele) as well as PMP31 and PMP32. PMP47A and PMP47B share 95% sequence identity at the amino acid level. PMP31 and PMP32 each contain 256 amino acids and are highly similar (97% identity) in protein sequence. Both PMP31 and PMP32 are predicted to span the membrane once or twice. All abundant PMPs of C. boidinii are basic in charge; they all have predicted isoelectric points above 10. RNAs corresponding to the PMP47s and to PMPs31-32 are strongly induced by methanol, oleic acid and D-alanine. While the PMP47s probably encode substrate carriers, the functions of PMP31 and PMP32 from C. boidinii are still unknown.
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Affiliation(s)
- M Moreno
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas 75235-9041
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30
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McCammon MT, McNew JA, Willy PJ, Goodman JM. An internal region of the peroxisomal membrane protein PMP47 is essential for sorting to peroxisomes. J Cell Biol 1994; 124:915-25. [PMID: 8132713 PMCID: PMC2119970 DOI: 10.1083/jcb.124.6.915] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Targeting sequences on peroxisomal membrane proteins have not yet been identified. We have attempted to find such a sequence within PMP47, a protein of the methylotrophic yeast, Candida boidinii. This protein of 423 amino acids shows sequence similarity with proteins in the family of mitochondrial carrier proteins. As such, it is predicted to have six membrane-spanning domains. Protease susceptibility experiments are consistent with a six-membrane-spanning model for PMP47, although the topology for the peroxisomal protein is inverted compared with the mitochondrial carrier proteins. PMP47 contains two potential peroxisomal targeting sequences (PTS1), an internal SKL (residues 320-322) and a carboxy terminal AKE (residues 421-423). Using a heterologous in vivo sorting system, we show that efficient sorting occurs in the absence of both sequences. Analysis of PMP47-dihydrofolate reductase (DHFR) fusion proteins revealed that amino acids 1-199 of PMP47, which contain the first three putative membrane spans, do not contain the necessary targeting information, whereas a fusion with amino acids 1-267, which contains five spans, is fully competent for sorting to peroxisomes. Similarly, a DHFR fusion construct containing residues 268-423 did not target to peroxisomes while residues 203-420 appeared to sort to that organelle, albeit at lower efficiency than the 1-267 construct. However, DHFR constructs containing only amino acids 185-267 or 203-267 of PMP47 were not found to be associated with peroxisomes. We conclude that amino acids 199-267 are necessary for peroxisomal targeting, although additional sequences may be required for efficient sorting to, or retention by, the organelles.
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Affiliation(s)
- M T McCammon
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas 75235-9041
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31
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32
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Diestelkötter P, Just WW. In vitro insertion of the 22-kD peroxisomal membrane protein into isolated rat liver peroxisomes. J Biophys Biochem Cytol 1993; 123:1717-25. [PMID: 8276892 PMCID: PMC2290900 DOI: 10.1083/jcb.123.6.1717] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The membrane insertion of the 22-kD integral peroxisomal membrane protein (PMP 22) was studied in a system in which peroxisomes isolated from rat liver were incubated with the [35S]methionine-labeled in vitro translation product of PMP 22 mRNA. Membrane insertion of PMP 22 was demonstrated by protease treatment of peroxisomes in the absence and presence of detergent. Approximately 35% of total in vitro translated PMP 22 became protease resistant after a 1-h incubation at 26 degrees C. Import was dependent on time and temperature, did not require ATP or GTP and was not inhibited by N-ethylmaleimide treatment of neither the soluble components of the translation mixture nor of the isolated peroxisomes. In contrast to these results it was recently shown that the import of the peroxisomal marker, firefly luciferase, into peroxisomes of permeabilized cells was dependent on ATP hydrolysis and was blocked by N-ethylmaleimide pretreatment of the cytosol-depleted cells (Rapp et al., 1993; Wendland and Subramani, 1993). Therefore, the present data suggest that insertion of PMP 22 into the peroxisomal membrane and translocation of firefly luciferase into peroxisomes follow distinct mechanisms. At low temperature binding of PMP 22 to the peroxisomal membrane was not influenced whereas insertion was strongly inhibited. Pretreatment of peroxisomes with subtilisin reduced binding to a low level and completely abolished insertion. Therefore it is suggested that binding is prerequisite to insertion and that insertion may be mediated by a proteinaceous receptor.
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