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The krebs cycle enzyme α-ketoglutarate decarboxylase is an essential glycosomal protein in bloodstream African trypanosomes. EUKARYOTIC CELL 2014; 14:206-15. [PMID: 25416237 DOI: 10.1128/ec.00214-14] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
α-Ketoglutarate decarboxylase (α-KDE1) is a Krebs cycle enzyme found in the mitochondrion of the procyclic form (PF) of Trypanosoma brucei. The bloodstream form (BF) of T. brucei lacks a functional Krebs cycle and relies exclusively on glycolysis for ATP production. Despite the lack of a functional Krebs cycle, α-KDE1 was expressed in BF T. brucei and RNA interference knockdown of α-KDE1 mRNA resulted in rapid growth arrest and killing. Cell death was preceded by progressive swelling of the flagellar pocket as a consequence of recruitment of both flagellar and plasma membranes into the pocket. BF T. brucei expressing an epitope-tagged copy of α-KDE1 showed localization to glycosomes and not the mitochondrion. We used a cell line transfected with a reporter construct containing the N-terminal sequence of α-KDE1 fused to green fluorescent protein to examine the requirements for glycosome targeting. We found that the N-terminal 18 amino acids of α-KDE1 contain overlapping mitochondrion- and peroxisome-targeting sequences and are sufficient to direct localization to the glycosome in BF T. brucei. These results suggest that α-KDE1 has a novel moonlighting function outside the mitochondrion in BF T. brucei.
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Purine utilization proteins in the Eurotiales: Cellular compartmentalization, phylogenetic conservation and divergence. Fungal Genet Biol 2014; 69:96-108. [DOI: 10.1016/j.fgb.2014.06.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 05/29/2014] [Accepted: 06/10/2014] [Indexed: 12/28/2022]
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Analysis of the Leishmania peroxin 7 interactions with peroxin 5, peroxin 14 and PTS2 ligands. Biochem J 2014; 460:273-82. [DOI: 10.1042/bj20131628] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
LPEX7 (Leishmania peroxin 7) is essential for targeting newly synthesized proteins with a PTS2 (peroxisome-targeting signal type 2) import signal into the glycosome. In the present paper, we describe the biophysical characterization of a functional LPEX7 isolated from Escherichia coli inclusion bodies. Pull-down assays showed that LPEX7 binds the interacting partners LdPEX5 (Leishmania donovani peroxin 5) and LdPEX14, but, more importantly, this receptor can specifically bind PTS2 cargo proteins in the monomeric and dimeric states. However, in the absence of interacting partners, LPEX7 preferentially adopts a tetrameric structure. Mapping studies localized the LdPEX5- and LdPEX14-binding sites to the N-terminal portion of LPEX7. Deletion of the first 52 residues abolished LdPEX14 association without altering the LdPEX5 interaction. Intrinsic fluorescence techniques suggested that each LPEX7 subunit has a single unique binding site for each of the respective interacting partners LdPEX5, LdPEX14 and PTS2 cargo proteins. Extrinsic fluorescence studies with ANS (8-anilinonaphthalene-1-sulfonic acid) demonstrated that LPEX7 contains a surface-exposed hydrophobic region(s) that was not altered by the binding of a PTS2 protein or LdPEX5. However, in the presence of these ligands, the accessibility of the hydrophobic domain was dramatically restricted, suggesting that both ligands are necessary to induce notable conformational changes in LPEX7. In contrast, binding of LdPEX14 did not alter the hydrophobic domain on LPEX7. It is possible that the hydrophobic surfaces on LPEX7 may be a crucial characteristic for the shuttling of this receptor in and out of the glycosome.
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Lüscher A, Lamprea-Burgunder E, Graf FE, de Koning HP, Mäser P. Trypanosoma brucei adenine-phosphoribosyltransferases mediate adenine salvage and aminopurinol susceptibility but not adenine toxicity. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2013; 4:55-63. [PMID: 24596669 PMCID: PMC3940079 DOI: 10.1016/j.ijpddr.2013.12.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 11/30/2013] [Accepted: 12/03/2013] [Indexed: 11/30/2022]
Abstract
African trypanosomes possess two distinct adenine phosphoribosyltransferases. Trypanosoma brucei TbAPRT1 is cytosolic, TbAPRT2 localizes to the glycosome. Aprt1,2 null mutants are viable but do not incorporate adenine into nucleotides. Aprt1,2 null mutants are resistant to aminopurinol but still sensitive to adenine. Aminopurinol is a trypanocide with submicromolar activity against T. brucei.
African trypanosomes, like all obligate parasitic protozoa, cannot synthesize purines de novo and import purines from their hosts to build nucleic acids. The purine salvage pathways of Trypanosoma brucei being redundant, none of the involved enzymes is likely to be essential. Nevertheless they can be of pharmacological interest due to their role in activation of purine nucleobase or nucleoside analogues, which only become toxic when converted to nucleotides. Aminopurine antimetabolites, in particular, are potent trypanocides and even adenine itself is toxic to trypanosomes at elevated concentrations. Here we report on the T. brucei adenine phosphoribosyltransferases TbAPRT1 and TbAPRT2, encoded by the two genes Tb927.7.1780 and Tb927.7.1790, located in tandem on chromosome seven. The duplication is syntenic in all available Trypanosoma genomes but not in Leishmania. While TbAPRT1 is cytosolic, TbAPRT2 possesses a glycosomal targeting signal and co-localizes with the glycosomal marker aldolase. Interestingly, the distribution of glycosomal targeting signals among trypanosomatid adenine phosphoribosyltransferases is not consistent with their phylogeny, indicating that the acquisition of adenine salvage to the glycosome happened after the radiation of Trypanosoma. Double null mutant T. brucei Δtbaprt1,2 exhibited no growth phenotype but no longer incorporated exogenous adenine into the nucleotide pool. This, however, did not reduce their sensitivity to adenine. The Δtbaprt1,2 trypanosomes were resistant to the adenine isomer aminopurinol, indicating that it is activated by phosphoribosyl transfer. Aminopurinol was about 1000-fold more toxic to bloodstream-form T. brucei than the corresponding hypoxanthine isomer allopurinol. Aminopurinol uptake was not dependent on the aminopurine permease P2 that has been implicated in drug resistance.
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Affiliation(s)
- Alexandra Lüscher
- Institute of Cell Biology, University of Bern, 3012 Bern, Switzerland
| | | | - Fabrice E Graf
- Swiss Tropical and Public Health Institute, 4051 Basel, Switzerland ; University of Basel, 4000 Basel, Switzerland
| | - Harry P de Koning
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow G12 8RA, UK
| | - Pascal Mäser
- Swiss Tropical and Public Health Institute, 4051 Basel, Switzerland ; University of Basel, 4000 Basel, Switzerland
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Platta HW, Hagen S, Reidick C, Erdmann R. The peroxisomal receptor dislocation pathway: to the exportomer and beyond. Biochimie 2013; 98:16-28. [PMID: 24345375 DOI: 10.1016/j.biochi.2013.12.009] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 12/05/2013] [Indexed: 12/29/2022]
Abstract
The biogenesis of peroxisomes is an ubiquitin-dependent process. In particular, the import of matrix proteins into the peroxisomal lumen requires the modification of import receptors with ubiquitin. The matrix proteins are synthesized on free polyribosomes in the cytosol and are recognized by import receptors via a peroxisomal targeting sequence (PTS). Subsequent to the transport of the receptor/cargo-complex to the peroxisomal membrane and the release of the cargo into the peroxisomal lumen, the PTS-receptors are exported back to the cytosol for further rounds of matrix protein import. The exportomer represents the molecular machinery required for the retrotranslocation of the PTS-receptors. It comprises enzymes for the ubiquitination as well as for the ATP-dependent extraction of the PTS-receptors from the peroxisomal membrane. Furthermore, recent evidence indicates a mechanistic interconnection of the ATP-dependent removal of the PTS-receptors with the translocation of the matrix protein into the organellar lumen. Interestingly, the components of the peroxisomal exportomer seem also to be involved in cellular tasks that are distinct from the ubiquitination and dislocation of the peroxisomal PTS-receptors. This includes work that indicates a central function of this machinery in the export of peroxisomal matrix proteins in plants, while a subset of exportomer components is involved in the meiocyte formation in some fungi, the peroxisome-chloroplast contact during photorespiration in plants and possibly even the selective degradation of peroxisomes via pexophagy. In this review, we want to discuss the central role of the exportomer during matrix protein import, but also highlight distinct roles of exportomer constituents in additional cellular processes. This article is part of a Special Issue entitled: Peroxisomes: biogenesis, functions and diseases.
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Affiliation(s)
- Harald W Platta
- Biochemie Intrazellulärer Transportprozesse, Ruhr-Universität Bochum, Universitätsstr. 150, D-44780 Bochum, Germany.
| | - Stefanie Hagen
- Systembiochemie, Ruhr-Universität Bochum, Universitätsstr. 150, D-44780 Bochum, Germany
| | - Christina Reidick
- Biochemie Intrazellulärer Transportprozesse, Ruhr-Universität Bochum, Universitätsstr. 150, D-44780 Bochum, Germany
| | - Ralf Erdmann
- Systembiochemie, Ruhr-Universität Bochum, Universitätsstr. 150, D-44780 Bochum, Germany.
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Ast J, Stiebler AC, Freitag J, Bölker M. Dual targeting of peroxisomal proteins. Front Physiol 2013; 4:297. [PMID: 24151469 PMCID: PMC3798809 DOI: 10.3389/fphys.2013.00297] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Accepted: 09/28/2013] [Indexed: 01/08/2023] Open
Abstract
Cellular compartmentalization into organelles serves to separate biological processes within the environment of a single cell. While some metabolic reactions are specific to a single organelle, others occur in more than one cellular compartment. Specific targeting of proteins to compartments inside of eukaryotic cells is mediated by defined sequence motifs. To achieve multiple targeting to different compartments cells use a variety of strategies. Here, we focus on mechanisms leading to dual targeting of peroxisomal proteins. In many instances, isoforms of peroxisomal proteins with distinct intracellular localization are encoded by separate genes. But also single genes can give rise to differentially localized proteins. Different isoforms can be generated by use of alternative transcriptional start sites, by differential splicing or ribosomal read-through of stop codons. In all these cases different peptide variants are produced, of which only one carries a peroxisomal targeting signal. Alternatively, peroxisomal proteins contain additional signals that compete for intracellular targeting. Dual localization of proteins residing in both the cytoplasm and in peroxisomes may also result from use of inefficient targeting signals. The recent observation that some bona fide cytoplasmic enzymes were also found in peroxisomes indicates that dual targeting of proteins to both the cytoplasm and the peroxisome might be more widespread. Although current knowledge of proteins exhibiting only partial peroxisomal targeting is far from being complete, we speculate that the metabolic capacity of peroxisomes might be larger than previously assumed.
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Affiliation(s)
- Julia Ast
- Department of Biology, Philipps University Marburg Marburg, Germany
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57
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Hasan S, Platta HW, Erdmann R. Import of proteins into the peroxisomal matrix. Front Physiol 2013; 4:261. [PMID: 24069002 PMCID: PMC3781343 DOI: 10.3389/fphys.2013.00261] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Accepted: 09/03/2013] [Indexed: 12/03/2022] Open
Abstract
Peroxisomes constitute a dynamic compartment in all nucleated cells. They fulfill diverse metabolic tasks in response to environmental changes and cellular demands. This adaptation is implemented by modulation of the enzyme content of the organelles, which is accomplished by dynamically operating peroxisomal protein transport machineries. Soluble import receptors recognize their newly synthesized cargo proteins in the cytosol and ferry them to the peroxisomal membrane. Subsequently, the cargo is translocated into the matrix, where the receptor is ubiquitinated and exported back to the cytosol for further rounds of matrix protein import. This review discusses the recent progress in our understanding of the peroxisomal matrix protein import and its regulation by ubiquitination events as well as the current view on the translocation mechanism of folded proteins into peroxisomes. This article is part of a Special Issue entitled: Origin and spatiotemporal dynamics of the peroxisomal endomembrane system.
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Affiliation(s)
- Sohel Hasan
- Systembiochemie, Medizinische Fakultät, Ruhr-Universität Bochum Bochum, Germany
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58
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Crystal structure of peroxisomal targeting signal-2 bound to its receptor complex Pex7p–Pex21p. Nat Struct Mol Biol 2013; 20:987-93. [DOI: 10.1038/nsmb.2618] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 05/13/2013] [Indexed: 12/26/2022]
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Krause C, Rosewich H, Woehler A, Gärtner J. Functional analysis of PEX13 mutation in a Zellweger syndrome spectrum patient reveals novel homooligomerization of PEX13 and its role in human peroxisome biogenesis. Hum Mol Genet 2013; 22:3844-57. [PMID: 23716570 DOI: 10.1093/hmg/ddt238] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In humans, the concerted action of at least 13 different peroxisomal PEX proteins is needed for proper peroxisome biogenesis. Mutations in any of these PEX genes can lead to lethal neurometabolic disorders of the Zellweger syndrome spectrum (ZSS). Previously, we identified the W313G mutation located within the SH3 domain of the peroxisomal protein, PEX13. As this tryptophan residue is highly conserved in almost all known SH3 proteins, we investigated the pathogenic mechanism of the W313G mutation and its role in PEX13 interactions and functions in peroxisome biogenesis. Here, we report for the first time that human PEX13 interacts with itself in peroxisomes in living cells. We demonstrate that the import of PTS1 (peroxisomal targeting signal 1) proteins is specifically disrupted when homooligomerization of PEX13 is interrupted. Live cell FRET microscopy in living cells as well as co-immunoprecipitation experiments reveal that the highly conserved W313 residue is important for self-association of PEX13 but is not required for interaction with PEX14, a well-established interaction partner at the peroxisomal membrane. Experiments with truncated constructs indicate that although the W313G mutation resides in the C-terminal SH3 domain, the N-terminal half is necessary for peroxisomal localization, which in turn appears to be crucial for homooligomerization. Furthermore, rescue of homooligomerization in the W313G mutant cells through complementation with truncation constructs restores import of peroxisomal matrix proteins. Taken together, the thorough analyses of a ZSS patient mutation unraveled the general cell biological function of PEX13 and its mechanism in the import of peroxisomal matrix PTS1 proteins.
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CmPEX6, a gene involved in peroxisome biogenesis, is essential for parasitism and conidiation by the sclerotial parasite Coniothyrium minitans. Appl Environ Microbiol 2013; 79:3658-66. [PMID: 23563946 DOI: 10.1128/aem.00375-13] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Coniothyrium minitans is a sclerotial parasite of the plant-pathogenic fungus Sclerotinia sclerotiorum, and conidial production and parasitism are two important aspects for commercialization of this biological control agent. To understand the mechanism of conidiation and parasitism at the molecular level, we constructed a transfer DNA (tDNA) insertional library with the wild-type strain ZS-1. A conidiation-deficient mutant, ZS-1TN22803, was uncovered through screening of this library. This mutant could produce pycnidia on potato dextrose agar (PDA), but most were immature and did not bear conidia. Moreover, this mutant lost the ability to parasitize or rot the sclerotia of S. sclerotiorum. Analysis of the tDNA flanking sequences revealed that a peroxisome biogenesis factor 6 (PEX6) homolog of Saccharomyces cerevisiae, named CmPEX6, was disrupted by the tDNA insertion in this mutant. Targeted gene replacement and gene complementation tests confirmed that a null mutation of CmPEX6 was responsible for the phenotype of ZS-1TN22803. Further analysis showed that both ZS-1TN22803 and the targeted replacement mutants could not grow on PDA medium containing oleic acid, and they produced much less nitric oxide (NO) and hydrogen peroxide (H2O2) than wild-type strain ZS-1. The conidiation of ZS-1TN22803 was partially restored by adding acetyl-CoA or glyoxylic acid to the growth media. Our results suggest that fatty acid β-oxidation, reactive oxygen and nitrogen species, and possibly other unknown pathways in peroxisomes are involved in conidiation and parasitism by C. minitans.
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Mizuno Y, Ninomiya Y, Nakachi Y, Iseki M, Iwasa H, Akita M, Tsukui T, Shimozawa N, Ito C, Toshimori K, Nishimukai M, Hara H, Maeba R, Okazaki T, Alodaib ANA, Amoudi MA, Jacob M, Alkuraya FS, Horai Y, Watanabe M, Motegi H, Wakana S, Noda T, Kurochkin IV, Mizuno Y, Schönbach C, Okazaki Y. Tysnd1 deficiency in mice interferes with the peroxisomal localization of PTS2 enzymes, causing lipid metabolic abnormalities and male infertility. PLoS Genet 2013; 9:e1003286. [PMID: 23459139 PMCID: PMC3573110 DOI: 10.1371/journal.pgen.1003286] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 12/12/2012] [Indexed: 12/03/2022] Open
Abstract
Peroxisomes are subcellular organelles involved in lipid metabolic processes, including those of very-long-chain fatty acids and branched-chain fatty acids, among others. Peroxisome matrix proteins are synthesized in the cytoplasm. Targeting signals (PTS or peroxisomal targeting signal) at the C-terminus (PTS1) or N-terminus (PTS2) of peroxisomal matrix proteins mediate their import into the organelle. In the case of PTS2-containing proteins, the PTS2 signal is cleaved from the protein when transported into peroxisomes. The functional mechanism of PTS2 processing, however, is poorly understood. Previously we identified Tysnd1 (Trypsin domain containing 1) and biochemically characterized it as a peroxisomal cysteine endopeptidase that directly processes PTS2-containing prethiolase Acaa1 and PTS1-containing Acox1, Hsd17b4, and ScpX. The latter three enzymes are crucial components of the very-long-chain fatty acids β-oxidation pathway. To clarify the in vivo functions and physiological role of Tysnd1, we analyzed the phenotype of Tysnd1(-/-) mice. Male Tysnd1(-/-) mice are infertile, and the epididymal sperms lack the acrosomal cap. These phenotypic features are most likely the result of changes in the molecular species composition of choline and ethanolamine plasmalogens. Tysnd1(-/-) mice also developed liver dysfunctions when the phytanic acid precursor phytol was orally administered. Phyh and Agps are known PTS2-containing proteins, but were identified as novel Tysnd1 substrates. Loss of Tysnd1 interferes with the peroxisomal localization of Acaa1, Phyh, and Agps, which might cause the mild Zellweger syndrome spectrum-resembling phenotypes. Our data established that peroxisomal processing protease Tysnd1 is necessary to mediate the physiological functions of PTS2-containing substrates.
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Affiliation(s)
- Yumi Mizuno
- Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
| | - Yuichi Ninomiya
- Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
| | - Yutaka Nakachi
- Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
| | - Mioko Iseki
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
| | - Hiroyasu Iwasa
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
| | - Masumi Akita
- Division of Morphological Science, Biomedical Research Center, Saitama Medical University, Iruma-gun, Saitama, Japan
| | - Tohru Tsukui
- Experimental Animal Laboratory, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
| | - Nobuyuki Shimozawa
- Division of Genomics Research, Life Science Research Center, Gifu University, Gifu, Japan
| | - Chizuru Ito
- Department of Anatomy and Developmental Biology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Kiyotaka Toshimori
- Department of Anatomy and Developmental Biology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Megumi Nishimukai
- Laboratory of Nutritional Biochemistry, Research Group of Food Science, Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Hiroshi Hara
- Laboratory of Nutritional Biochemistry, Research Group of Food Science, Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Ryouta Maeba
- Department of Biochemistry, Teikyo University School of Medicine, Itabashi-ku, Tokyo, Japan
| | - Tomoki Okazaki
- Department of Biochemistry, Teikyo University School of Medicine, Itabashi-ku, Tokyo, Japan
| | - Ali Nasser Ali Alodaib
- Developmental Genetics Department, Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Kingdom of Saudi Arabia
- The National Newborn Screening Laboratory, Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Kingdom of Saudi Arabia
| | - Mohammed Al Amoudi
- Developmental Genetics Department, Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Kingdom of Saudi Arabia
- The National Newborn Screening Laboratory, Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Kingdom of Saudi Arabia
| | - Minnie Jacob
- Developmental Genetics Department, Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Kingdom of Saudi Arabia
- The National Newborn Screening Laboratory, Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Kingdom of Saudi Arabia
| | - Fowzan S. Alkuraya
- Developmental Genetics Department, Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Kingdom of Saudi Arabia
- Department of Pediatrics, King Khalid University Hospital and College of Medicine, King Saud University, Riyadh, Kingdom of Saudi Arabia
- Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh, Kingdom of Saudi Arabia
| | - Yasushi Horai
- Department of Internal Medicine, School of Medicine, Keio University, Shinjuku-ku, Tokyo, Japan
| | - Mitsuhiro Watanabe
- Department of Internal Medicine, School of Medicine, Keio University, Shinjuku-ku, Tokyo, Japan
- Graduate School of Media and Governance, Keio University, Tokyo, Japan
- Faculty of Environment and Information Studies, Keio University, Tokyo, Japan
| | - Hiromi Motegi
- Team for Advanced Development and Evaluation of Human Disease Models, Japan Mouse Clinic, BioResource Center (BRC), Tsukuba, Ibaraki, Japan
| | - Shigeharu Wakana
- The Japan Mouse Clinic, RIKEN BioResource Center (BRC), Tsukuba, Ibaraki, Japan
| | - Tetsuo Noda
- Team for Advanced Development and Evaluation of Human Disease Models, Japan Mouse Clinic, BioResource Center (BRC), Tsukuba, Ibaraki, Japan
- The Cancer Institute of the Japanese Foundation for Cancer Research, Koto-ku, Tokyo, Japan
| | - Igor V. Kurochkin
- Genome and Gene Expression Data Analysis Division, Bioinformatics Institute, A*STAR, Singapore, Republic of Singapore
| | - Yosuke Mizuno
- Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
| | - Christian Schönbach
- Division of Genomics and Genetics, School of Biological Sciences, Nanyang Technological University, Singapore, Republic of Singapore
| | - Yasushi Okazaki
- Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
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Moser AB, Hey J, Dranchak PK, Karaman MW, Zhao J, Cox LA, Ryder OA, Hacia JG. Diverse captive non-human primates with phytanic acid-deficient diets rich in plant products have substantial phytanic acid levels in their red blood cells. Lipids Health Dis 2013; 12:10. [PMID: 23379307 PMCID: PMC3571895 DOI: 10.1186/1476-511x-12-10] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 01/31/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Humans and rodents with impaired phytanic acid (PA) metabolism can accumulate toxic stores of PA that have deleterious effects on multiple organ systems. Ruminants and certain fish obtain PA from the microbial degradation of dietary chlorophyll and/or through chlorophyll-derived precursors. In contrast, humans cannot derive PA from chlorophyll and instead normally obtain it only from meat, dairy, and fish products. RESULTS Captive apes and Old world monkeys had significantly higher red blood cell (RBC) PA levels relative to humans when all subjects were fed PA-deficient diets. Given the adverse health effects resulting from PA over accumulation, we investigated the molecular evolution of thirteen PA metabolism genes in apes, Old world monkeys, and New world monkeys. All non-human primate (NHP) orthologs are predicted to encode full-length proteins with the marmoset Phyh gene containing a rare, but functional, GA splice donor dinucleotide. Acox2, Scp2, and Pecr sequences had amino acid positions with accelerated substitution rates while Amacr had significant variation in evolutionary rates in apes relative to other primates. CONCLUSIONS Unlike humans, diverse captive NHPs with PA-deficient diets rich in plant products have substantial RBC PA levels. The favored hypothesis is that NHPs can derive significant amounts of PA from the degradation of ingested chlorophyll through gut fermentation. If correct, this raises the possibility that RBC PA levels could serve as a biomarker for evaluating the digestive health of captive NHPs. Furthermore, the evolutionary rates of the several genes relevant to PA metabolism provide candidate genetic adaptations to NHP diets.
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Affiliation(s)
- Ann B Moser
- Department of Biochemistry and Molecular Biology, Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA 90089, USA
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Farnesyl diphosphate synthase, the target for nitrogen-containing bisphosphonate drugs, is a peroxisomal enzyme in the model system Dictyostelium discoideum. Biochem J 2012; 447:353-61. [PMID: 22849378 PMCID: PMC3465988 DOI: 10.1042/bj20120750] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
NBP (nitrogen-containing bisphosphonate) drugs protect against excessive osteoclast-mediated bone resorption. After binding to bone mineral, they are taken up selectively by the osteoclasts and inhibit the essential enzyme FDPS (farnesyl diphosphate synthase). NBPs inhibit also growth of amoebae of Dictyostelium discoideum in which their target is again FDPS. A fusion protein between FDPS and GFP (green fluorescent protein) was found, in D. discoideum, to localize to peroxisomes and to confer resistance to the NBP alendronate. GFP was also directed to peroxisomes by a fragment of FDPS comprising amino acids 1–22. This contains a sequence of nine amino acids that closely resembles the nonapeptide PTS2 (peroxisomal targeting signal type 2): there is only a single amino acid mismatch between the two sequences. Mutation analysis confirmed that the atypical PTS2 directs FDPS into peroxisomes. Furthermore, expression of the D. discoideum FDPS–GFP fusion protein in strains of Saccharomyces cerevisiae defective in peroxisomal protein import demonstrated that import of FDPS into peroxisomes was blocked in a strain lacking the PTS2-dependent import pathway. The peroxisomal location of FDPS in D. discoideum indicates that NBPs have to cross the peroxisomal membrane before they can bind to their target.
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Abstract
Peroxisomes are remarkably versatile cell organelles whose size, shape, number, and protein content can vary greatly depending on the organism, the developmental stage of the organism’s life cycle, and the environment in which the organism lives. The main functions usually associated with peroxisomes include the metabolism of lipids and reactive oxygen species. However, in recent years, it has become clear that these organelles may also act as intracellular signaling platforms that mediate developmental decisions by modulating extraperoxisomal concentrations of several second messengers. To fulfill their functions, peroxisomes physically and functionally interact with other cell organelles, including mitochondria and the endoplasmic reticulum. Defects in peroxisome dynamics can lead to organelle dysfunction and have been associated with various human disorders. The purpose of this paper is to thoroughly summarize and discuss the current concepts underlying peroxisome formation, multiplication, and degradation. In addition, this paper will briefly highlight what is known about the interplay between peroxisomes and other cell organelles and explore the physiological and pathological implications of this interorganellar crosstalk.
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Affiliation(s)
- Marc Fransen
- Department of Cellular and Molecular Medicine, KU Leuven, Herestraat 49, P.O. Box 601, 3000 Leuven, Belgium
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65
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Pieuchot L, Jedd G. Peroxisome Assembly and Functional Diversity in Eukaryotic Microorganisms. Annu Rev Microbiol 2012; 66:237-63. [DOI: 10.1146/annurev-micro-092611-150126] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Laurent Pieuchot
- Temasek Life Sciences Laboratory and Department of Biological Sciences, National University of Singapore, 117604 Singapore; ,
| | - Gregory Jedd
- Temasek Life Sciences Laboratory and Department of Biological Sciences, National University of Singapore, 117604 Singapore; ,
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66
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Son H, Min K, Lee J, Choi GJ, Kim JC, Lee YW. Mitochondrial carnitine-dependent acetyl coenzyme A transport is required for normal sexual and asexual development of the ascomycete Gibberella zeae. EUKARYOTIC CELL 2012; 11:1143-53. [PMID: 22798392 PMCID: PMC3445975 DOI: 10.1128/ec.00104-12] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Accepted: 07/06/2012] [Indexed: 11/20/2022]
Abstract
Fungi have evolved efficient metabolic mechanisms for the exact temporal (developmental stages) and spatial (organelles) production of acetyl coenzyme A (acetyl-CoA). We previously demonstrated mechanistic roles of several acetyl-CoA synthetic enzymes, namely, ATP citrate lyase and acetyl-CoA synthetases (ACSs), in the plant-pathogenic fungus Gibberella zeae. In this study, we characterized two carnitine acetyltransferases (CATs; CAT1 and CAT2) to obtain a better understanding of the metabolic processes occurring in G. zeae. We found that CAT1 functioned as an alternative source of acetyl-CoA required for lipid accumulation in an ACS1 deletion mutant. Moreover, deletion of CAT1 and/or CAT2 resulted in various defects, including changes to vegetative growth, asexual/sexual development, trichothecene production, and virulence. Although CAT1 is associated primarily with peroxisomal CAT function, mislocalization experiments showed that the role of CAT1 in acetyl-CoA transport between the mitochondria and cytosol is important for sexual and asexual development in G. zeae. Taking these data together, we concluded that G. zeae CATs are responsible for facilitating the exchange of acetyl-CoA across intracellular membranes, particularly between the mitochondria and the cytosol, during various developmental stages.
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Affiliation(s)
- Hokyoung Son
- Department of Agricultural Biotechnology and Center for Fungal Pathogenesis, Seoul National University, Seoul, Republic of Korea
| | - Kyunghun Min
- Department of Agricultural Biotechnology and Center for Fungal Pathogenesis, Seoul National University, Seoul, Republic of Korea
| | - Jungkwan Lee
- Department of Applied Biology, Dong-A University, Busan, Republic of Korea
| | - Gyung Ja Choi
- Eco-Friendly New Materials Research Group, Research Center for Biobased Chemistry, Division of Convergence Chemistry, Korea Research Institute of Chemical Technology, Daejeon, Republic of Korea
| | - Jin-Cheol Kim
- Eco-Friendly New Materials Research Group, Research Center for Biobased Chemistry, Division of Convergence Chemistry, Korea Research Institute of Chemical Technology, Daejeon, Republic of Korea
| | - Yin-Won Lee
- Department of Agricultural Biotechnology and Center for Fungal Pathogenesis, Seoul National University, Seoul, Republic of Korea
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67
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Verplaetse E, Gualdrón-López M, Chevalier N, Michels PAM. Studies on the organization of the docking complex involved in matrix protein import into glycosomes of Trypanosoma brucei. Biochem Biophys Res Commun 2012; 424:781-5. [PMID: 22809509 DOI: 10.1016/j.bbrc.2012.07.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 07/09/2012] [Indexed: 10/28/2022]
Abstract
Trypanosoma brucei contains peroxisome-like organelles designated glycosomes because they sequester the major part of the glycolytic pathway. Import of proteins into the peroxisomal matrix involves a protein complex associated with the peroxisomal membrane of which PEX13 is a component. Two very different PEX13 isoforms have recently been identified in T. brucei. A striking feature of one of the isoforms, TbPEX13.1, is the presence of a C-terminal type 1 peroxisomal-targeting signal (PTS1), the tripeptide TKL, conserved in its orthologues in all members of the Trypanosomatidae family so far studied, but absent from TbPEX13.2 and the PEX13s in all other organisms. Despite their differences, both TbPEX13s function as part of a docking complex for cytosolic receptors with bound matrix proteins to be imported. We further characterized TbPEX13.1's function in glycosomal matrix-protein import. It provides a frame to anchor another docking complex component, PEX14, to the glycosomal membrane or information to correctly position it within the membrane. To investigate the possible function of the C-terminal TKL, we determined the topology of the C-terminal half of TbPEX13.1 in the membrane and show that its SH3 domain, located immediately adjacent to the PTS1, is at the cytosolic face.
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Affiliation(s)
- Emilie Verplaetse
- Research Unit for Tropical Diseases, de Duve Institute, Laboratory of Biochemistry, Université catholique de Louvain, Brussels, Belgium
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68
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Strijbis K, van den Burg J, Visser WF, van den Berg M, Distel B. Alternative splicing directs dual localization of Candida albicans 6-phosphogluconate dehydrogenase to cytosol and peroxisomes. FEMS Yeast Res 2011; 12:61-8. [PMID: 22094058 DOI: 10.1111/j.1567-1364.2011.00761.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2011] [Accepted: 11/05/2011] [Indexed: 11/28/2022] Open
Abstract
The pentose phosphate pathway (PPP) is the main source of NADPH in the cell and therefore essential for the maintenance of the redox balance and anabolic reactions. NADPH is produced by the two dehydrogenases in the oxidative branch of the PPP: glucose-6-phosphate dehydrogenase (Zwf1) and 6-phosphogluconate dehydrogenase (Gnd1). We observed that in the commensal fungus Candida albicans these two enzymes contain putative peroxisomal targeting signals (PTSs): Zwf1 has a putative PTS1, while the annotated intron of GND1 encodes a PTS2. By subcellular fractionation and fluorescence microscopy, we show that both enzymes have a dual localization in which the majority is cytosolic, but a small fraction is peroxisome associated. Analysis of GND1 transcripts revealed that dual targeting of Gnd1 is directed by alternative splicing resulting in two Gnd1 isoforms, one without targeting signals localized to the cytosol and one with an N-terminal PTS2 targeted to peroxisomes. To our knowledge, Gnd1 is the first example of dual targeting of a protein by alternative splicing in C. albicans. In silico analysis suggests that PTS-mediated peroxisomal targeting of Zwf1 and Gnd1 is conserved across closely related Candida species. We discuss putative functions of the peroxisomal oxidative PPP in these organisms.
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Affiliation(s)
- Karin Strijbis
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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69
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Clastre M, Papon N, Courdavault V, Giglioli-Guivarc’h N, St-Pierre B, Simkin AJ. Subcellular evidence for the involvement of peroxisomes in plant isoprenoid biosynthesis. PLANT SIGNALING & BEHAVIOR 2011; 6:2044-6. [PMID: 22080790 PMCID: PMC3337203 DOI: 10.4161/psb.6.12.18173] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The role of peroxisomes in isoprenoid metabolism, especially in plants, has been questioned in several reports. A recent study of Sapir-Mir et al. revealed that the two isoforms of isopentenyl diphosphate (IPP) isomerase, catalyzing the isomerisation of IPP to dimethylallyl diphosphate (DMAPP) are found in the peroxisome. In this addendum, we provide additional data describing the peroxisomal localization of 5-phosphomevalonate kinase and mevalonate 5-diphosphate decarboxylase, the last two enzymes of the mevalonic acid pathway leading to IPP. This finding was reinforced in our latest report showing that a short isoform of farnesyl diphosphate, using IPP and DMAPP as substrates, is also targeted to the organelle. Therefore, the classical sequestration of isoprenoid biosynthesis between plastids and cytosol/ER can be revisited by including the peroxisome as an additional isoprenoid biosynthetic compartment within plant cells.
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Affiliation(s)
- Marc Clastre
- Université François-Rabelais de Tours; EA2106 Biomolécules et Biotechnologies Végétales; Tours, France
| | - Nicolas Papon
- Université François-Rabelais de Tours; EA2106 Biomolécules et Biotechnologies Végétales; Tours, France
| | - Vincent Courdavault
- Université François-Rabelais de Tours; EA2106 Biomolécules et Biotechnologies Végétales; Tours, France
| | | | - Benoit St-Pierre
- Université François-Rabelais de Tours; EA2106 Biomolécules et Biotechnologies Végétales; Tours, France
| | - Andrew J. Simkin
- Université François-Rabelais de Tours; EA2106 Biomolécules et Biotechnologies Végétales; Tours, France
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70
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Liu F, Lu Y, Pieuchot L, Dhavale T, Jedd G. Import oligomers induce positive feedback to promote peroxisome differentiation and control organelle abundance. Dev Cell 2011; 21:457-68. [PMID: 21920312 DOI: 10.1016/j.devcel.2011.08.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Revised: 05/06/2011] [Accepted: 08/02/2011] [Indexed: 11/28/2022]
Abstract
A fundamental question in cell biology is how cells control organelle composition and abundance. Woronin bodies are fungal peroxisomes centered on a crystalline core of the self-assembled HEX protein. Despite using the canonical peroxisome import machinery for biogenesis, Woronin bodies are scarce compared to the overall peroxisome population. Here, we show that HEX oligomers promote the differentiation of a subpopulation of peroxisomes, which become enlarged and highly active in matrix protein import. HEX physically associates with the essential matrix import peroxin, PEX26, and promotes its enrichment in the membrane of differentiated peroxisomes. In addition, a PEX26 mutant that disrupts differentiation produces increased numbers of aberrantly small Woronin bodies. Our data suggest a mechanism where HEX oligomers recruit a key component of the import machinery, which promotes the import of additional HEX. This type of positive feedback provides a basic mechanism for the production of an organelle subpopulation of distinct composition and abundance.
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Affiliation(s)
- Fangfang Liu
- Temasek Life Sciences Laboratory and Department of Biological Sciences, National University of Singapore, Singapore
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71
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Thabet I, Guirimand G, Courdavault V, Papon N, Godet S, Dutilleul C, Bouzid S, Giglioli-Guivarc'h N, Clastre M, Simkin AJ. The subcellular localization of periwinkle farnesyl diphosphate synthase provides insight into the role of peroxisome in isoprenoid biosynthesis. JOURNAL OF PLANT PHYSIOLOGY 2011; 168:2110-6. [PMID: 21872968 DOI: 10.1016/j.jplph.2011.06.017] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Revised: 06/06/2011] [Accepted: 06/27/2011] [Indexed: 05/24/2023]
Abstract
Farnesyl diphosphate (FPP) synthase (FPS: EC.2.5.1.1, EC.2.5.1.10) catalyzes the formation of FPP from isopentenyl diphosphate and dimethylallyl diphosphate via two successive condensation reactions. A cDNA designated CrFPS, encoding a protein showing high similarities with trans-type short FPS isoforms, was isolated from the Madagascar periwinkle (Catharanthus roseus). This cDNA was shown to functionally complement the lethal FPS deletion mutant in the yeast Saccharomyces cerevisiae. At the subcellular level, while short FPS isoforms are usually described as cytosolic proteins, we showed, using transient transformations of C. roseus cells with yellow fluorescent protein-fused constructs, that CrFPS is targeted to peroxisomes. This finding is discussed in relation to the subcellular distribution of FPS isoforms in plants and animals and opens new perspectives towards the understanding of isoprenoid biosynthesis.
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Affiliation(s)
- Insaf Thabet
- Université François-Rabelais de Tours, EA2106, Biomolécules et Biotechnologies Végétales, 37200 Tours, France
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72
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Kunze M, Neuberger G, Maurer-Stroh S, Ma J, Eck T, Braverman N, Schmid JA, Eisenhaber F, Berger J. Structural requirements for interaction of peroxisomal targeting signal 2 and its receptor PEX7. J Biol Chem 2011; 286:45048-62. [PMID: 22057399 DOI: 10.1074/jbc.m111.301853] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The import of a subset of peroxisomal matrix proteins is mediated by the peroxisomal targeting signal 2 (PTS2). The results of our sequence and physical property analysis of known PTS2 signals and of a mutational study of the least characterized amino acids of a canonical PTS2 motif indicate that PTS2 forms an amphipathic helix accumulating all conserved residues on one side. Three-dimensional structural modeling of the PTS2 receptor PEX7 reveals a groove with an evolutionarily conserved charge distribution complementary to PTS2 signals. Mammalian two-hybrid assays and cross-complementation of a mutation in PTS2 by a compensatory mutation in PEX7 confirm the interaction site. An unstructured linker region separates the PTS2 signal from the core protein. This additional information on PTS2 signals was used to generate a PTS2 prediction algorithm that enabled us to identify novel PTS2 signals within human proteins and to describe KChIP4 as a novel peroxisomal protein.
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Affiliation(s)
- Markus Kunze
- Center for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090 Vienna, Austria
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73
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Simkin AJ, Guirimand G, Papon N, Courdavault V, Thabet I, Ginis O, Bouzid S, Giglioli-Guivarc'h N, Clastre M. Peroxisomal localisation of the final steps of the mevalonic acid pathway in planta. PLANTA 2011; 234:903-14. [PMID: 21655959 DOI: 10.1007/s00425-011-1444-6] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 05/17/2011] [Indexed: 05/19/2023]
Abstract
In plants, the mevalonic acid (MVA) pathway provides precursors for the formation of triterpenes, sesquiterpenes, phytosterols and primary metabolites important for cell integrity. Here, we have cloned the cDNA encoding enzymes catalysing the final three steps of the MVA pathway from Madagascar periwinkle (Catharanthus roseus), mevalonate kinase (MVK), 5-phosphomevalonate kinase (PMK) and mevalonate 5-diphosphate decarboxylase (MVD). These cDNA were shown to functionally complement MVA pathway deletion mutants in the yeast Saccharomyces cerevisiae. Transient transformations of C. roseus cells with yellow fluorescent protein (YFP)-fused constructs reveal that PMK and MVD are localised to the peroxisomes, while MVK was cytosolic. These compartmentalisation results were confirmed using the Arabidopsis thaliana MVK, PMK and MVD sequences fused to YFP. Based on these observations and the arguments raised here we conclude that the final steps of the plant MVA pathway are localised to the peroxisome.
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Affiliation(s)
- Andrew J Simkin
- EA 2106, Biomolécules et Biotechnologies Végétales, Université François-Rabelais de Tours, 31 Avenue Monge, 37200, Tours, France.
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74
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Completing the purine utilisation pathway of Aspergillus nidulans. Fungal Genet Biol 2011; 48:840-8. [DOI: 10.1016/j.fgb.2011.03.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Revised: 03/07/2011] [Accepted: 03/07/2011] [Indexed: 11/22/2022]
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75
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Abstract
The biogenesis of peroxisomal matrix and membrane proteins is substantially different from the biogenesis of proteins of other subcellular compartments, such as mitochondria and chloroplasts, that are of endosymbiotic origin. Proteins are targeted to the peroxisome matrix through interactions between specific targeting sequences and receptor proteins, followed by protein translocation across the peroxisomal membrane. Recent advances have shed light on the nature of the peroxisomal translocon in matrix protein import and the molecular mechanisms of receptor recycling. Furthermore, the endoplasmic reticulum has been shown to play an important role in peroxisomal membrane protein biogenesis. Defining the molecular events in peroxisome assembly may enhance our understanding of the etiology of human peroxisome biogenesis disorders.
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Affiliation(s)
- Changle Ma
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, CA 92093, USA
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76
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Role of carnitine acetyltransferases in acetyl coenzyme A metabolism in Aspergillus nidulans. EUKARYOTIC CELL 2011; 10:547-55. [PMID: 21296915 DOI: 10.1128/ec.00295-10] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The flow of carbon metabolites between cellular compartments is an essential feature of fungal metabolism. During growth on ethanol, acetate, or fatty acids, acetyl units must enter the mitochondrion for metabolism via the tricarboxylic acid cycle, and acetyl coenzyme A (acetyl-CoA) in the cytoplasm is essential for the biosynthetic reactions and for protein acetylation. Acetyl-CoA is produced in the cytoplasm by acetyl-CoA synthetase during growth on acetate and ethanol while β-oxidation of fatty acids generates acetyl-CoA in peroxisomes. The acetyl-carnitine shuttle in which acetyl-CoA is reversibly converted to acetyl-carnitine by carnitine acetyltransferase (CAT) enzymes is important for intracellular transport of acetyl units. In the filamentous ascomycete Aspergillus nidulans, a cytoplasmic CAT, encoded by facC, is essential for growth on sources of cytoplasmic acetyl-CoA while a second CAT, encoded by the acuJ gene, is essential for growth on fatty acids as well as acetate. We have shown that AcuJ contains an N-terminal mitochondrial targeting sequence and a C-terminal peroxisomal targeting sequence (PTS) and is localized to both peroxisomes and mitochondria, independent of the carbon source. Mislocalization of AcuJ to the cytoplasm does not result in loss of growth on acetate but prevents growth on fatty acids. Therefore, while mitochondrial AcuJ is essential for the transfer of acetyl units to mitochondria, peroxisomal localization is required only for transfer from peroxisomes to mitochondria. Peroxisomal AcuJ was not required for the import of acetyl-CoA into peroxisomes for conversion to malate by malate synthase (MLS), and export of acetyl-CoA from peroxisomes to the cytoplasm was found to be independent of FacC when MLS was mislocalized to the cytoplasm.
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77
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Galland N, Michels PAM. Comparison of the peroxisomal matrix protein import system of different organisms. Exploration of possibilities for developing inhibitors of the import system of trypanosomatids for anti-parasite chemotherapy. Eur J Cell Biol 2010; 89:621-37. [PMID: 20435370 DOI: 10.1016/j.ejcb.2010.04.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Revised: 03/28/2010] [Accepted: 04/06/2010] [Indexed: 10/19/2022] Open
Abstract
In recent decades, research on peroxisome biogenesis has been particularly boosted since the role of these organelles in metabolism became unraveled. Indeed in plants, yeasts and fungi, peroxisomes play an important role in the adaptation of metabolism during developmental processes and/or altered environmental conditions. In mammals their importance is illustrated by the fact that several severe human inherited diseases have been identified as peroxisome biogenesis disorders (PBD). Particularly interesting are the glycosomes - peroxisome-like organelles in trypanosomatids where the major part of the glycolytic pathway is sequestered - because it was demonstrated that proper compartmentalization of matrix proteins inside glycosomes is essential for the parasite. Although the overall process of peroxisome biogenesis seems well conserved between species, careful study of the literature reveals nonetheless many differences at various steps. In this review, we present a comparison of the first two steps of peroxisome biogenesis - receptor loading and docking at the peroxisomal membrane - in yeasts, mammals, plants and trypanosomatids and highlight major differences in the import process between species despite the conservation of (some of) the proteins involved. Some of the unique features of the process as it occurs in trypanosomatids will be discussed with regard to the possibilities for exploiting them for the development of compounds that could specifically disturb interactions between trypanosomatid peroxins. This strategy could eventually lead to the discovery of drugs against the diseases caused by these parasites.
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Affiliation(s)
- Nathalie Galland
- Research Unit for Tropical Diseases, de Duve Institute, Brussels, Belgium
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78
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Abstract
Since the proposal of the signal hypothesis on protein subcellular sorting, a number of computational analyses have been performed in this field. A typical example is the development of prediction algorithms for the subcellular localization sites of input protein sequences. In this review, we mainly focus on the biological grounds of the prediction methods rather than the algorithmic issues because we believe the former will be more fruitful for future development. Recent advances on the study of protein sorting signals will hopefully be incorporated into future prediction methods. Unfortunately, many of the state-of-the-art methods are published without sufficient objective tests. In fact, a simple test employed in this article shows that the performance of specifically developed predictors is not significantly better than that of a homology search. We suspect that this is a general problem associated with the interpretation of genome sequences, which have evolved through gene duplication and speciation.
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Affiliation(s)
- Kenichiro Imai
- Computational Biology Research Center, AIST, Tokyo, Japan
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79
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Hynes MJ, Murray SL, Kahn FK. Deletion of the RING-finger peroxin 2 gene inAspergillus nidulansdoes not affect meiotic development. FEMS Microbiol Lett 2010; 306:67-71. [DOI: 10.1111/j.1574-6968.2010.01934.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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80
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Islinger M, Cardoso MJR, Schrader M. Be different--the diversity of peroxisomes in the animal kingdom. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1803:881-97. [PMID: 20347886 DOI: 10.1016/j.bbamcr.2010.03.013] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2010] [Revised: 03/15/2010] [Accepted: 03/18/2010] [Indexed: 10/19/2022]
Abstract
Peroxisomes represent so-called "multipurpose organelles" as they contribute to various anabolic as well as catabolic pathways. Thus, with respect to the physiological specialization of an individual organ or animal species, peroxisomes exhibit a functional diversity, which is documented by significant variations in their proteome. These differences are usually regarded as an adaptational response to the nutritional and environmental life conditions of a specific organism. Thus, human peroxisomes can be regarded as an in part physiologically unique organellar entity fulfilling metabolic functions that differ from our animal model systems. In line with this, a profound understanding on how peroxisomes acquired functional heterogeneity in terms of an evolutionary and mechanistic background is required. This review summarizes our current knowledge on the heterogeneity of peroxisomal physiology, providing insights into the genetic and cell biological mechanisms, which lead to the differential localization or expression of peroxisomal proteins and further gives an overview on peroxisomal biochemical pathways, which are specialized in different animal species and organs. Moreover, it addresses the impact of proteome studies on our understanding of differential peroxisome function describing the utility of mass spectrometry and computer-assisted algorithms to identify peroxisomal target sequences for the detection of new organ- or species-specific peroxisomal proteins.
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Affiliation(s)
- M Islinger
- Department of Anatomy and Cell Biology, Ruprecht-Karls University, 69120 Heidelberg, Germany
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81
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Galland N, de Walque S, Voncken FGJ, Verlinde CLMJ, Michels PAM. An internal sequence targets Trypanosoma brucei triosephosphate isomerase to glycosomes. Mol Biochem Parasitol 2010; 171:45-9. [PMID: 20138091 DOI: 10.1016/j.molbiopara.2010.01.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Revised: 01/08/2010] [Accepted: 01/18/2010] [Indexed: 12/01/2022]
Abstract
In kinetoplastid protists, glycolysis is compartmentalized in glycosomes, organelles belonging to the peroxisome family. The Trypanosoma brucei glycosomal enzyme triosephosphate isomerase (TPI) does not contain either of the two established peroxisome-targeting signals, but we identified a 22 amino acids long fragment, present at an internal position of the polypeptide, that has the capacity to route a reporter protein to glycosomes in transfected trypanosomes, as demonstrated by cell-fractionation experiments and corroborating immunofluorescence studies. This polypeptide-internal routing information seems to be unique for the sequence of the trypanosome enzyme: a reporter protein fused to a Saccharomyces cerevisiae peptide containing the sequence corresponding to the 22-residue fragment of the T. brucei enzyme, was not targeted to glycosomes. In yeasts, as in most other organisms, TPI is indeed exclusively present in the cytosol. These results suggest that it may be possible to develop new trypanocidal drugs by targeting specifically the glycosome import mechanism of TPI.
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Affiliation(s)
- Nathalie Galland
- Research Unit for Tropical Diseases, de Duve Institute and Laboratory of Biochemistry, Université catholique de Louvain, TROP 74.39, Avenue Hippocrate 74, B-1200 Brussels, Belgium
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82
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Jung S, Marelli M, Rachubinski RA, Goodlett DR, Aitchison JD. Dynamic changes in the subcellular distribution of Gpd1p in response to cell stress. J Biol Chem 2009; 285:6739-49. [PMID: 20026609 DOI: 10.1074/jbc.m109.058552] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Gpd1p is a cytosolic NAD(+)-dependent glycerol 3-phosphate dehydrogenase that also localizes to peroxisomes and plays an essential role in the cellular response to osmotic stress and a role in redox balance. Here, we show that Gpd1p is directed to peroxisomes by virtue of an N-terminal type 2 peroxisomal targeting signal (PTS2) in a Pex7p-dependent manner. Significantly, localization of Gpd1p to peroxisomes is dependent on the metabolic status of cells and the phosphorylation of aminoacyl residues adjacent to the targeting signal. Exposure of cells to osmotic stress induces changes in the subcellular distribution of Gpd1p to the cytosol and nucleus. This behavior is similar to Pnc1p, which is coordinately expressed with Gpd1p, and under conditions of cell stress changes its subcellular distribution from peroxisomes to the nucleus where it mediates chromatin silencing. Although peroxisomes are necessary for the beta-oxidation of fatty acids in yeast, the localization of Gpd1p to peroxisomes is not. Rather, shifts in the distribution of Gpd1p to different cellular compartments in response to changing cellular status suggests a role for Gpd1p in the spatial regulation of redox potential, a process critical to cell survival, especially under the complex stress conditions expected to occur in the wild.
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Affiliation(s)
- Sunhee Jung
- Institute for Systems Biology, Seattle, Washington 98103, USA
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83
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Van Moerkercke A, Schauvinhold I, Pichersky E, Haring MA, Schuurink RC. A plant thiolase involved in benzoic acid biosynthesis and volatile benzenoid production. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 60:292-302. [PMID: 19659733 DOI: 10.1111/j.1365-313x.2009.03953.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The exact biosynthetic pathways leading to benzoic acid (BA) formation in plants are not known, but labeling experiments indicate the contribution of both beta-oxidative and non-beta-oxidative pathways. In Petunia hybrida BA is a key precursor for the production of volatile benzenoids by its flowers. Using functional genomics, we identified a 3-ketoacyl-CoA thiolase, PhKAT1, which is involved in the benzenoid biosynthetic pathway and the production of BA. PhKAT1 is localised in the peroxisomes, where it is important for the formation of benzoyl-CoA-related compounds. Silencing of PhKAT1 resulted in a major reduction in BA and benzenoid formation, leaving the production of other phenylpropanoid-related volatiles unaffected. During the night, when volatile benzenoid production is highest, it is largely the beta-oxidative pathway that contributes to the formation of BA and benzenoids. Our studies add the benzenoid biosynthetic pathway to the list of pathways in which 3-ketoacyl-CoA thiolases are involved in plants.
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Affiliation(s)
- Alex Van Moerkercke
- Department of Plant Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, Amsterdam, The Netherlands
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84
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Abstract
Peroxisomes play an important role in lipid metabolic pathways and are implicated in many human disorders. Their biogenesis has been studied over the last two decades using many uni and multi-cellular model systems and many aspects of the mechanisms and proteins involved in peroxisome biogenesis are conserved from yeast to humans. In this manuscript we review the recent progress made in our understanding of the mechanisms by which matrix and membrane proteins are sorted to and assembled into peroxisomes.
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Affiliation(s)
- Changle Ma
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0322, USA
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85
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Penha LL, Sant'Anna CB, Mendonça-Previato L, Cunha-e-Silva NL, Previato JO, Lima APCA. Sorting of phosphoglucomutase to glycosomes in Trypanosoma cruzi is mediated by an internal domain. Glycobiology 2009; 19:1462-72. [PMID: 19696235 DOI: 10.1093/glycob/cwp121] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Trypanosoma cruzi relies on highly galactosylated molecules as virulence factors and the enzymes involved in sugar biosynthesis are potential therapeutic targets. The synthesis of UDP-galactose in T. cruzi requires the activity of phosphoglucomutase (PGM), the enzyme that catalyzes the interconversion of glucose-6-phosphate and glucose-1-phosphate. Several enzymes that participate in carbohydrate metabolism in trypanosomes are confined to specialized peroxisome-like organelles called glycosomes. The majority of glycosomal proteins contain peroxisome-targeting signals (PTS) at the COOH- or at the amino-terminus, which drive their transport to glycosomes. We had previously identified the T. cruzi PGM gene (TcPGM) and demonstrated that it encodes a functional enzyme. Here, we show that, in contrast to yeast and mammalian cells, TcPGM resides in glycosomes of the parasite. However, no classical PTS1 or PTS2 motif is present in its sequence. We investigated glycosomal targeting by generating T. cruzi cell lines expressing different domains of TcPGM fused to the green fluorescent protein (GFP). The analysis of the subcellular localization of fusion proteins revealed that an internal targeting signal of TcPGM, residing between amino acid residues 260 and 380, is capable of targeting GFP to glycosomes. These results demonstrate that, in T. cruzi, PGM import into glycosomes is mediated by a novel non-PTS domain that is located internally in the protein.
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Affiliation(s)
- Luciana L Penha
- Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Bloco G, Universidade Federal do Rio de Janeiro, 21 944 970, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, RJ, Brazil
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86
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Michels PAM, Moyersoen J, Krazy H, Galland N, Herman M, Hannaert V. Peroxisomes, glyoxysomes and glycosomes (Review). Mol Membr Biol 2009; 22:133-45. [PMID: 16092531 DOI: 10.1080/09687860400024186] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Peroxisomes, glyoxysomes and glycosomes are related organelles found in different organisms. The morphology and enzymic content of the different members of this organelle family differ considerably, and may also be highly dependent on the cell's environmental conditions or life cycle. However, all peroxisome-like organelles have in common a number of characteristic enzymes or enzyme systems, notably enzymes dealing with reactive oxygen species. All organelles of the family follow essentially the same route of biogenesis, but with species-specific differences. Sets of proteins called peroxins are involved in different aspects of the formation and proliferation of peroxisomes such as import of proteins in the organellar matrix, insertion of proteins in the membrane, etc. In different eukaryotic lineages these functions are carried out by often--but not always--homologous yet poorly conserved peroxins. The process of biogenesis and the nature of the proteins involved suggest that all members of the peroxisome family evolved from a single organelle in an ancestral eukaryotic cell. This original peroxisome was possibly derived from a cellular membrane system such as the endoplasmic reticulum. Most of the organism-specific functions of the extant organelles have been acquired later in evolution.
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Affiliation(s)
- Paul A M Michels
- Research Unit for Tropical Diseases, Christian de Duve Institute of Cellular Pathology and Laboratory of Biochemistry, Université Catholique de Louvain, Brussels, Belgium.
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87
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Saikia S, Scott B. Functional analysis and subcellular localization of two geranylgeranyl diphosphate synthases from Penicillium paxilli. Mol Genet Genomics 2009; 282:257-71. [PMID: 19529962 PMCID: PMC2729982 DOI: 10.1007/s00438-009-0463-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2009] [Accepted: 05/28/2009] [Indexed: 10/26/2022]
Abstract
The filamentous fungus Penicillium paxilli contains two distinct geranylgeranyl diphosphate (GGPP) synthases, GgsA and GgsB (PaxG). PaxG and its homologues in Neotyphodium lolii and Fusarium fujikuroi are associated with diterpene secondary metabolite gene clusters. The genomes of other filamentous fungi including Aspergillus fumigatus, Aspergillus nidulans, Aspergillus niger, Aspergillus oryzae and Fusarium graminearum also contain two or more copies of GGPP synthase genes, although the diterpene metabolite capability of these fungi is not known. The objective of this study was to understand the biological significance of the presence of two copies of GGPP synthases in P. paxilli by investigating their subcellular localization. Using a carotenoid complementation assay and gene deletion analysis, we show that P. paxilli GgsA and PaxG have GGPP synthase activities and that paxG is required for paxilline biosynthesis, respectively. In the DeltapaxG mutant background ggsA was unable to complement paxilline biosynthesis. A GgsA-EGFP fusion protein was localized to punctuate organelles and the EGFP-GRV fusion protein, containing the C-terminus tripeptide GRV of PaxG, was localized to peroxisomes. A truncated PaxG mutant lacking the C-terminus tripeptide GRV was unable to complement a DeltapaxG mutant demonstrating that the tripeptide is functionally important for paxilline biosynthesis.
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Affiliation(s)
- Sanjay Saikia
- Institute of Molecular Biosciences, Massey University, Palmerston North, New Zealand.
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88
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Kiel JAKW, van den Berg MA, Fusetti F, Poolman B, Bovenberg RAL, Veenhuis M, van der Klei IJ. Matching the proteome to the genome: the microbody of penicillin-producing Penicillium chrysogenum cells. Funct Integr Genomics 2009; 9:167-84. [PMID: 19156454 DOI: 10.1007/s10142-009-0110-6] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2008] [Revised: 01/05/2009] [Accepted: 01/05/2009] [Indexed: 10/21/2022]
Abstract
In the filamentous fungus Penicillium chrysogenum, microbodies are essential for penicillin biosynthesis. To better understand the role of these organelles in antibiotics production, we determined the matrix enzyme contents of P. chrysogenum microbodies. Using a novel in silico approach, we first obtained a catalogue of 200 P. chrysogenum proteins with putative microbody targeting signals (PTSs). This included two orthologs of proteins involved in cephalosporin biosynthesis, which we demonstrate to be bona fide microbody matrix constituents. Subsequently, we performed a proteomics based inventory of P. chrysogenum microbody matrix proteins using nano-LC-MS/MS analysis. We identified 89 microbody proteins, 79 with a PTS, including the two known microbody-borne penicillin biosynthesis enzymes, isopenicillin N:acyl CoA acyltransferase and phenylacetyl-CoA ligase. Comparative analysis revealed that 69 out of 79 PTS proteins identified experimentally were in the reference list. A prominent microbody protein was identified as a novel fumarate reductase-cytochrome b5 fusion protein, which contains an internal PTS2 between the two functional domains. We show that this protein indeed localizes to P. chrysogenum microbodies.
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Affiliation(s)
- Jan A K W Kiel
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, AA Haren, The Netherlands.
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89
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Identification, characterization and essentiality of the unusual peroxin 13 from Trypanosoma brucei. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1793:516-27. [PMID: 19185591 DOI: 10.1016/j.bbamcr.2008.12.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2008] [Revised: 12/08/2008] [Accepted: 12/18/2008] [Indexed: 11/20/2022]
Abstract
Peroxin 13 (PEX13) is one of the components of a peroxisomal membrane complex involved in import of proteins into the matrix of the organelles and has previously been characterized in a variety of organisms. Trypanosomatids (Trypanosoma, Leishmania), protozoan parasites having peroxisome-like organelles designated glycosomes, possess an unusual PEX13 which shares very low sequence identity with others and lacks some typical PEX13 characteristics. It was identified in the databases through its multiple YGx motifs present in a glycine-rich N-terminal region of low sequence complexity. Like other PEX13s, it contains predicted transmembrane segments and a SH3 domain in its C-terminal half. The localization of T. brucei PEX13 in the glycosomal membrane was confirmed by expression of a fusion construct with Green Fluorescent Protein, and western blot analysis of purified organelles and membranes. The C-terminal half of the protein was shown to interact with the third of three pentapeptide repeats of the previously characterized PEX5, the receptor of glycosomal proteins with a type 1 peroxisome-targeting signal, and with PEX14, another component of the same peroxisomal protein import complex in the membrane. PEX13 is essential for the parasite; depletion by RNA interference results in mislocalization of glycosomal proteins and death of the parasites.
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90
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Mizuno Y, Kurochkin IV, Herberth M, Okazaki Y, Schönbach C. Predicted mouse peroxisome-targeted proteins and their actual subcellular locations. BMC Bioinformatics 2008; 9 Suppl 12:S16. [PMID: 19091015 PMCID: PMC2638156 DOI: 10.1186/1471-2105-9-s12-s16] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The import of most intraperoxisomal proteins is mediated by peroxisome targeting signals at their C-termini (PTS1) or N-terminal regions (PTS2). Both signals have been integrated in subcellular location prediction programs. However their present performance, particularly of PTS2-targeting did not seem fitting for large-scale screening of sequences. RESULTS We modified an earlier reported PTS1 screening method to identify PTS2-containing mouse candidates using a combination of computational and manual annotation. For rapid confirmation of five new PTS2- and two previously identified PTS1-containing candidates we developed the new cell line CHO-perRed which stably expresses the peroxisomal marker dsRed-PTS1. Using CHO-perRed we confirmed the peroxisomal localization of PTS1-targeted candidate Zadh2. Preliminary characterization of Zadh2 expression suggested non-PPARalpha mediated activation. Notably, none of the PTS2 candidates located to peroxisomes. CONCLUSION In a few cases the PTS may oscillate from "silent" to "functional" depending on its surface accessibility indicating the potential for context-dependent conditional subcellular sorting. Overall, PTS2-targeting predictions are unlikely to improve without generation and integration of new experimental data from location proteomics, protein structures and quantitative Pex7 PTS2 peptide binding assays.
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Affiliation(s)
- Yumi Mizuno
- Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Hidaka, Saitama 350-1241, Japan.
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91
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Genetic analysis of the role of peroxisomes in the utilization of acetate and fatty acids in Aspergillus nidulans. Genetics 2008; 178:1355-69. [PMID: 18245820 DOI: 10.1534/genetics.107.085795] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Peroxisomes are organelles containing a diverse array of enzymes. In fungi they are important for carbon source utilization, pathogenesis, development, and secondary metabolism. We have studied Aspergillus nidulans peroxin (pex) mutants isolated by virtue of their inability to grow on butyrate or by the inactivation of specific pex genes. While all pex mutants are able to form colonies, those unable to import PTS1 proteins are partially defective in asexual and sexual development. The pex mutants are able to grow on acetate but are affected in growth on fatty acids, indicating a requirement for the peroxisomal localization of beta-oxidation enzymes. However, mislocalization of malate synthase does not prevent growth on either fatty acids or acetate, showing that the glyoxylate cycle does not require peroxisomal localization. Proliferation of peroxisomes is dependent on fatty acids, but not on acetate, and on PexK (Pex11), expression of which is activated by the FarA transcription factor. Proliferation was greatly reduced in a farADelta strain. A mutation affecting a mitochodrial ketoacyl-CoA thiolase and disruption of a mitochondrial hydroxy-acyl-CoA dehydrogenase gene prevented growth on short-chain but not long-chain fatty acids. Together with previous results, this is consistent with growth on even-numbered short-chain fatty acids requiring a mitochondrial as well as a peroxisomal beta-oxidation pathway. The mitochondrial pathway is not required for growth on valerate or for long-chain fatty acid utilization.
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92
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Thoms S, Debelyy MO, Nau K, Meyer HE, Erdmann R. Lpx1p is a peroxisomal lipase required for normal peroxisome morphology. FEBS J 2008; 275:504-14. [DOI: 10.1111/j.1742-4658.2007.06217.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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93
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Montero-Morán GM, Li M, Rendòn-Huerta E, Jourdan F, Lowe DJ, Stumpff-Kane AW, Feig M, Scazzocchio C, Hausinger RP. Purification and characterization of the FeII- and alpha-ketoglutarate-dependent xanthine hydroxylase from Aspergillus nidulans. Biochemistry 2007; 46:5293-304. [PMID: 17429948 PMCID: PMC2525507 DOI: 10.1021/bi700065h] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
His6-tagged xanthine/alpha-ketoglutarate (alphaKG) dioxygenase (XanA) of Aspergillus nidulans was purified from both the fungal mycelium and recombinant Escherichia coli cells, and the properties of the two forms of the protein were compared. Evidence was obtained for both N- and O-linked glycosylation on the fungus-derived XanA, which aggregates into an apparent dodecamer, while bacterium-derived XanA is free of glycosylation and behaves as a monomer. Immunological methods identify phosphothreonine in both forms of XanA, with phosphoserine also detected in the bacterium-derived protein. Mass spectrometric analysis confirms glycosylation and phosphorylation of the fungus-derived sample, which also undergoes extensive truncation at its amino terminus. Despite the major differences in the properties of these proteins, their kinetic parameters are similar (kcat = 30-70 s-1, Km of alphaKG = 31-50 muM, Km of xanthine approximately 45 muM, and pH optima at 7.0-7.4). The enzyme exhibits no significant isotope effect when [8-2H]xanthine is used; however, it demonstrates a 2-fold solvent deuterium isotope effect. CuII and ZnII potently inhibit the FeII-specific enzyme, whereas CoII, MnII, and NiII are weaker inhibitors. NaCl decreases the kcat and increases the Km of both alphaKG and xanthine. The alphaKG cosubstrate can be substituted with alpha-ketoadipate (9-fold decrease in kcat and 5-fold increase in the Km compared to those of the normal alpha-keto acid), while the alphaKG analogue N-oxalylglycine is a competitive inhibitor (Ki = 0.12 muM). No alternative purines effectively substitute for xanthine as a substrate, and only one purine analogue (6,8-dihydroxypurine) results in significant inhibition. Quenching of the endogenous fluorescence of the two enzyme forms by xanthine, alphaKG, and DHP was used to characterize their binding properties. A XanA homology model was generated on the basis of the structure of the related enzyme TauD (PDB entry 1OS7) and provided insights into the sites of posttranslational modification and substrate binding. These studies represent the first biochemical characterization of purified xanthine/alphaKG dioxygenase.
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Affiliation(s)
- Gabriela M Montero-Morán
- Institut de Génétique et de Microbiologie, Université Paris-Sud, Bâtiment 409, UMR 8621 CNRS, 91405 Orsay Cedex, France
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94
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Abstract
It is widely recognized that much of the information for determining the final subcellular localization of proteins is found in their amino acid sequences. Thus the prediction of protein localization sites is of both theoretical and practical interest. In most cases, the prediction has been attempted in two ways: one is based on the knowledge of experimentally characterized targeting signals, while the other utilizes the statistical differences of general sequence characteristics, such as amino acid composition, between localization sites. Both approaches have limitations, and it is recommended to check the results of various prediction methods based on different principles as well as training data. Recently, increased proteomic analyses of localization sites have provided new data to assess the current status of predictive methods. In this chapter we discuss these issues and close with an example illustrating the use of the WoLF PSORT web server for localization prediction.
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Affiliation(s)
- Kenta Nakai
- Laboratory of Functional Analysis in silico, Human Genome Center, Institute of Medical Science, University of Tokyo, Tokyo, Japan
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95
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Kovacs WJ, Tape KN, Shackelford JE, Duan X, Kasumov T, Kelleher JK, Brunengraber H, Krisans SK. Localization of the pre-squalene segment of the isoprenoid biosynthetic pathway in mammalian peroxisomes. Histochem Cell Biol 2006; 127:273-90. [PMID: 17180682 DOI: 10.1007/s00418-006-0254-6] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/31/2006] [Indexed: 10/23/2022]
Abstract
Previous studies have indicated that the early steps in the isoprenoid/cholesterol biosynthetic pathway occur in peroxisomes. However, the role of peroxisomes in cholesterol biosynthesis has recently been questioned in several reports concluding that three of the peroxisomal cholesterol biosynthetic enzymes, namely mevalonate kinase, phosphomevalonate kinase, and mevalonate diphosphate decarboxylase, do not localize to peroxisomes in human cells even though they contain consensus peroxisomal targeting signals. We re-investigated the subcellular localization of the cholesterol biosynthetic enzymes of the pre-squalene segment in human cells by using new stable isotopic techniques and data computations with isotopomer spectral analysis, in combination with immunofluorescence and cell permeabilization techniques. Our present findings clearly show and confirm previous studies that the pre-squalene segment of the cholesterol biosynthetic pathway is localized to peroxisomes. In addition, our data are consistent with the hypothesis that acetyl-CoA derived from peroxisomal beta-oxidation of very long-chain fatty acids and medium-chain dicarboxylic acids is preferentially channeled to cholesterol synthesis inside the peroxisomes without mixing with the cytosolic acetyl-CoA pool.
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Affiliation(s)
- Werner J Kovacs
- Department of Biology, San Diego State University, San Diego, CA, USA.
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96
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Lazarow PB. Chapter 3.1.7. The import receptor Pex7p and the PTS2 targeting sequence. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:1599-604. [PMID: 16996627 DOI: 10.1016/j.bbamcr.2006.08.011] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Revised: 07/25/2006] [Accepted: 08/18/2006] [Indexed: 10/24/2022]
Abstract
This chapter concerns one branch of the peroxisome import pathway for newly-synthesized peroxisomal proteins, specifically the branch for matrix proteins that contain a peroxisome targeting sequence type 2 (PTS2). The structure and utilization of the PTS2 are discussed, as well as the properties of the receptor, Pex7p, which recognizes the PTS2 sequence and conveys these proteins to the common translocation machinery in the peroxisome membrane. We also describe the recent evidence that this receptor recycles into the peroxisome matrix and back out to the cytosol in the course of its function. Pex7p is assisted in its functioning by several species-specific auxiliary proteins that are described in the following chapter.
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97
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Laliberté J, Labbé S. Mechanisms of copper loading on the Schizosaccharomyces pombe copper amine oxidase 1 expressed in Saccharomyces cerevisiae. MICROBIOLOGY (READING, ENGLAND) 2006; 152:2819-2830. [PMID: 16946276 DOI: 10.1099/mic.0.28998-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Copper amine oxidases (CAOs) are found in almost every living kingdom. Although Saccharomyces cerevisiae is one of the few yeast species that lacks an endogenous CAO, heterologous gene expression of CAOs from other organisms produces a functional enzyme. To begin to characterize their function and mechanisms of copper acquisition, two putative cao(+) genes from Schizosaccharomyces pombe were expressed in S. cerevisiae. Expression of spao1(+) resulted in the production of an active enzyme capable of catalysing the oxidative deamination of primary amines. On the other hand, expression of spao2(+) failed to produce an active CAO. Using a functional spao1(+)-GFP fusion allele, the SPAO1 protein was localized in the cytosol. Under copper-limiting conditions, yeast cells harbouring deletions of the MAC1, CTR1 and CTR3 genes were defective in amine oxidase activity. Likewise, atx1Delta null cells exhibited no CAO activity, while ccc2Delta mutant cells exhibited decreased levels of amine oxidase activity, and mutations in cox17Delta and ccs1Delta did not cause any defects in this activity. Copper-deprived S. cerevisiae cells expressing spao1(+) required a functional atx1(+) gene for growth on minimal medium containing ethylamine as the sole nitrogen source. Under these conditions, the inability of the atx1Delta cells to utilize ethylamine correlated with the lack of SPAO1 activity, in spite of the efficient expression of the protein. Cells carrying a disrupted ccc2Delta allele exhibited only weak growth on ethylamine medium containing a copper chelator. The results of these studies reveal that expression of the heterologous spao1(+) gene in S. cerevisiae is required for its growth in medium containing ethylamine as the sole nitrogen source, and that expression of an active Schiz. pombe SPAO1 protein in S. cerevisiae depends on the acquisition of copper through the high-affinity copper transporters Ctr1 and Ctr3, and the copper chaperone Atx1.
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Affiliation(s)
- Julie Laliberté
- Département de Biochimie, Université de Sherbrooke, 3001 12e Avenue Nord, Sherbrooke, Québec J1H 5N4, Canada
| | - Simon Labbé
- Département de Biochimie, Université de Sherbrooke, 3001 12e Avenue Nord, Sherbrooke, Québec J1H 5N4, Canada
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98
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Idnurm A, Giles SS, Perfect JR, Heitman J. Peroxisome function regulates growth on glucose in the basidiomycete fungus Cryptococcus neoformans. EUKARYOTIC CELL 2006; 6:60-72. [PMID: 17041184 PMCID: PMC1800366 DOI: 10.1128/ec.00214-06] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The function of the peroxisomes was examined in the pathogenic basidiomycete Cryptococcus neoformans. Recent studies reveal the glyoxylate pathway is required for virulence of diverse microbial pathogens of plants and animals. One exception is C. neoformans, in which isocitrate lyase (encoded by ICL1) was previously shown not to be required for virulence, and here this was extended to exclude also a role for malate synthase (encoded by MLS1). The role of peroxisomes, in which the glyoxylate pathway enzymes are localized in many organisms, was examined by mutation of two genes (PEX1 and PEX6) encoding AAA (ATPases associated with various cellular activities)-type proteins required for peroxisome formation. The pex1 and pex6 deletion mutants were unable to localize the fluorescent DsRED-SKL protein to peroxisomal punctate structures, in contrast to wild-type cells. pex1 and pex6 single mutants and a pex1 pex6 double mutant exhibit identical phenotypes, including abolished growth on fatty acids but no growth difference on acetate. Because both icl1 and mls1 mutants are unable to grow on acetate as the sole carbon source, these findings demonstrate that the glyoxylate pathway can function efficiently outside the peroxisome in C. neoformans. The pex1 mutant exhibits wild-type virulence in a murine inhalation model and in an insect host, demonstrating that peroxisomes are not required for virulence under these conditions. An unusual phenotype of the pex1 and pex6 mutants was that they grew poorly with glucose as the carbon source, but nearly wild type with galactose, which suggested impaired hexokinase function and that C. neoformans peroxisomes might function analogously to the glycosomes of the trypanosomid parasites. Deletion of the hexokinase HXK2 gene reduced growth in the presence of glucose and suppressed the growth defect of the pex1 mutant on glucose. The hexokinase 2 protein of C. neoformans contains a predicted peroxisome targeting signal (type 2) motif; however, Hxk2 fused to fluorescent proteins was not localized to peroxisomes. Thus, we hypothesize that glucose or glycolytic metabolites are utilized in the peroxisome by an as yet unidentified enzyme or regulate a pathway required by the fungus in the absence of peroxisomes.
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Affiliation(s)
- Alexander Idnurm
- Room 322 CARL Building, Box 3546, Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
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99
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Léon S, Zhang L, McDonald WH, Yates J, Cregg JM, Subramani S. Dynamics of the peroxisomal import cycle of PpPex20p: ubiquitin-dependent localization and regulation. ACTA ACUST UNITED AC 2006; 172:67-78. [PMID: 16390998 PMCID: PMC2063535 DOI: 10.1083/jcb.200508096] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We characterize the peroxin PpPex20p from Pichia pastoris and show its requirement for translocation of PTS2 cargoes into peroxisomes. PpPex20p docks at the peroxisomal membrane and translocates into peroxisomes. Its peroxisomal localization requires the docking peroxin Pex14p but not the peroxins Pex2p, Pex10p, and Pex12p, whose absence causes peroxisomal accumulation of Pex20p. Similarities between Pex5p and Pex20p were noted in their protein interactions and dynamics during import, and both contain a conserved NH2-terminal domain. In the absence of the E2-like Pex4p or the AAA proteins Pex1p and Pex6p, Pex20p is degraded via polyubiquitylation of residue K19, and the K19R mutation causes accumulation of Pex20p in peroxisome remnants. Finally, either interference with K48-branched polyubiquitylation or removal of the conserved NH2-terminal domain causes accumulation of Pex20p in peroxisomes, mimicking a defect in its recycling to the cytosol. Our data are consistent with a model in which Pex20p enters peroxisomes and recycles back to the cytosol in an ubiquitin-dependent manner.
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Affiliation(s)
- Sébastien Léon
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093
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Zhang L, Léon S, Subramani S. Two independent pathways traffic the intraperoxisomal peroxin PpPex8p into peroxisomes: mechanism and evolutionary implications. Mol Biol Cell 2005; 17:690-9. [PMID: 16319171 PMCID: PMC1356580 DOI: 10.1091/mbc.e05-08-0758] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Among peroxins involved in peroxisome biogenesis, only Pex8p is predominantly intraperoxisomal at steady state. Pex8p is necessary for peroxisomal matrix protein import via the PTS1 and PTS2 pathways. It is proposed to bridge two peroxisomal membrane subcomplexes comprised of the docking (Pex13p, Pex14p, Pex17p) and RING (Pex2p, Pex10p, Pex12p) peroxins and is also implicated in cargo release of PTS1 proteins in the matrix. We show that Pichia pastoris Pex8p (PpPex8p) enters the peroxisome matrix using two redundant pathways in a Pex14p-dependent, but Pex2p-independent, manner, showing that the intact importomer and RING subcomplex are not required for its import. One pathway depends on the TPR motifs in Pex5p, the C-terminal PTS1 sequence (AKL) in PpPex8p, and the intraperoxisomal presence of this peroxin. The alternative pathway uses the PTS2 receptor, Pex7p, its accessory protein, Pex20p, and a putative PTS2 motif in PpPex8p, but does not require intraperoxisomal PpPex8p. Pex20p interaction with PpPex8p is independent of Pex7p, but the interaction of PpPex8p with Pex7p requires Pex20p. These data suggest a direct interaction between PpPex8p and Pex20p. Our studies shed light on the mechanism and evolution of the dual import pathways for PpPex8p.
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Affiliation(s)
- Lan Zhang
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0322, USA
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