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Abstract
Peroxisomes are involved in a multitude of metabolic and catabolic pathways, as well as the innate immune system. Their dysfunction is linked to severe peroxisome-specific diseases, as well as cancer and neurodegenerative diseases. To ensure the ability of peroxisomes to fulfill their many roles in the organism, more than 100 different proteins are post-translationally imported into the peroxisomal membrane and matrix, and their functionality must be closely monitored. In this Review, we briefly discuss the import of peroxisomal membrane proteins, and we emphasize an updated view of both classical and alternative peroxisomal matrix protein import pathways. We highlight different quality control pathways that ensure the degradation of dysfunctional peroxisomal proteins. Finally, we compare peroxisomal matrix protein import with other systems that transport folded proteins across membranes, in particular the twin-arginine translocation (Tat) system and the nuclear pore.
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Affiliation(s)
- Markus Rudowitz
- Systems Biochemistry , Institute of Biochemistry and Pathobiochemistry, Faculty of Medicine, Ruhr University Bochum, Universitätsstr. 150, 44801 Bochum, Germany
| | - Ralf Erdmann
- Systems Biochemistry , Institute of Biochemistry and Pathobiochemistry, Faculty of Medicine, Ruhr University Bochum, Universitätsstr. 150, 44801 Bochum, Germany
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Germain K, Kim PK. Pexophagy: A Model for Selective Autophagy. Int J Mol Sci 2020; 21:ijms21020578. [PMID: 31963200 PMCID: PMC7013971 DOI: 10.3390/ijms21020578] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 01/09/2020] [Accepted: 01/13/2020] [Indexed: 01/03/2023] Open
Abstract
The removal of damaged or superfluous organelles from the cytosol by selective autophagy is required to maintain organelle function, quality control and overall cellular homeostasis. Precisely how substrate selectivity is achieved, and how individual substrates are degraded during selective autophagy in response to both extracellular and intracellular cues is not well understood. The aim of this review is to highlight pexophagy, the autophagic degradation of peroxisomes, as a model for selective autophagy. Peroxisomes are dynamic organelles whose abundance is rapidly modulated in response to metabolic demands. Peroxisomes are routinely turned over by pexophagy for organelle quality control yet can also be degraded by pexophagy in response to external stimuli such as amino acid starvation or hypoxia. This review discusses the molecular machinery and regulatory mechanisms governing substrate selectivity during both quality-control pexophagy and pexophagy in response to external stimuli, in yeast and mammalian systems. We draw lessons from pexophagy to infer how the cell may coordinate the degradation of individual substrates by selective autophagy across different cellular cues.
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Affiliation(s)
- Kyla Germain
- Cell Biology Program, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada;
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Peter K. Kim
- Cell Biology Program, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada;
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
- Correspondence: ; Tel.: +1-416-813-5983
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Wanders RJA. Peroxisomal disorders: Improved laboratory diagnosis, new defects and the complicated route to treatment. Mol Cell Probes 2018; 40:60-69. [PMID: 29438773 DOI: 10.1016/j.mcp.2018.02.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 02/01/2018] [Accepted: 02/02/2018] [Indexed: 12/15/2022]
Abstract
Peroxisomes catalyze a number of essential metabolic functions of which fatty acid alpha- and beta-oxidation, ether phospholipid biosynthesis, glyoxylate detoxification and bile acid synthesis are the most important. The key role of peroxisomes in humans is exemplified by the existence of a group of peroxisomal disorders, caused by mutations in > 30 different genes which code for proteins with a role in either peroxisome biogenesis or one of the metabolic pathways in peroxisomes. Technological advances in laboratory methods at the metabolite-, enzyme-, and molecular level have not only allowed the identification of new peroxisomal disorders but also new phenotypes associated with already identified genetic defects thus extending the clinical spectrum. Unfortunately, progress in the field of pathogenesis and treatment has lagged behind although there are certainly new and hopeful developments with respect to X-linked adrenoleukodystrophy and hyperoxaluria type 1.
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Affiliation(s)
- Ronald J A Wanders
- Department of Clinical Chemistry, Laboratory Genetic Metabolic Diseases, Emma Children's Hospital, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands; Department of Pediatrics, Laboratory Genetic Metabolic Diseases, Emma Children's Hospital, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
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4
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Hua R, Kim PK. Multiple paths to peroxisomes: Mechanism of peroxisome maintenance in mammals. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:881-91. [DOI: 10.1016/j.bbamcr.2015.09.026] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Revised: 09/18/2015] [Accepted: 09/21/2015] [Indexed: 12/19/2022]
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Agrawal G, Subramani S. De novo peroxisome biogenesis: Evolving concepts and conundrums. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1863:892-901. [PMID: 26381541 PMCID: PMC4791208 DOI: 10.1016/j.bbamcr.2015.09.014] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2015] [Revised: 09/10/2015] [Accepted: 09/11/2015] [Indexed: 10/23/2022]
Abstract
Peroxisomes proliferate by growth and division of pre-existing peroxisomes or could arise de novo. Though the de novo pathway of peroxisome biogenesis is a more recent discovery, several studies have highlighted key mechanistic details of the pathway. The endoplasmic reticulum (ER) is the primary source of lipids and proteins for the newly-formed peroxisomes. More recently, an intricate sorting process functioning at the ER has been proposed, that segregates specific PMPs first to peroxisome-specific ER domains (pER) and then assembles PMPs selectively into distinct pre-peroxisomal vesicles (ppVs) that later fuse to form import-competent peroxisomes. In addition, plausible roles of the three key peroxins Pex3, Pex16 and Pex19, which are also central to the growth and division pathway, have been suggested in the de novo process. In this review, we discuss key developments and highlight the unexplored avenues in de novo peroxisome biogenesis.
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Affiliation(s)
- Gaurav Agrawal
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, UC San Diego, La Jolla, CA 92093-0322, USA
| | - Suresh Subramani
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, UC San Diego, La Jolla, CA 92093-0322, USA.
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Mayerhofer PU, Bañó-Polo M, Mingarro I, Johnson AE. Human Peroxin PEX3 Is Co-translationally Integrated into the ER and Exits the ER in Budding Vesicles. Traffic 2015; 17:117-30. [PMID: 26572236 PMCID: PMC5064655 DOI: 10.1111/tra.12350] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 11/13/2015] [Accepted: 11/13/2015] [Indexed: 01/19/2023]
Abstract
The long-standing paradigm that all peroxisomal proteins are imported post-translationally into pre-existing peroxisomes has been challenged by the detection of peroxisomal membrane proteins (PMPs) inside the endoplasmic reticulum (ER). In mammals, the mechanisms of ER entry and exit of PMPs are completely unknown. We show that the human PMP PEX3 inserts co-translationally into the mammalian ER via the Sec61 translocon. Photocrosslinking and fluorescence spectroscopy studies demonstrate that the N-terminal transmembrane segment (TMS) of ribosome-bound PEX3 is recognized by the signal recognition particle (SRP). Binding to SRP is a prerequisite for targeting of the PEX3-containing ribosome•nascent chain complex (RNC) to the translocon, where an ordered multistep pathway integrates the nascent chain into the membrane adjacent to translocon proteins Sec61α and TRAM. This insertion of PEX3 into the ER is physiologically relevant because PEX3 then exits the ER via budding vesicles in an ATP-dependent process. This study identifies early steps in human peroxisomal biogenesis by demonstrating sequential stages of PMP passage through the mammalian ER.
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Affiliation(s)
- Peter U Mayerhofer
- Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, 440 Reynolds Medical Building, College Station, TX, 77843, USA.,Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt, Germany.,Present address: School of Biosciences & Medicine, University of Surrey, Guildford, GU2 7XH, UK
| | - Manuel Bañó-Polo
- Departament de Bioquimica i Biologia Molecular, Universitat de Valencia, C/ Dr. Moliner, 50, E-46100, Burjassot, Spain
| | - Ismael Mingarro
- Departament de Bioquimica i Biologia Molecular, Universitat de Valencia, C/ Dr. Moliner, 50, E-46100, Burjassot, Spain
| | - Arthur E Johnson
- Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, 440 Reynolds Medical Building, College Station, TX, 77843, USA.,Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA.,Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA
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Bender S, Reuter A, Eberle F, Einhorn E, Binder M, Bartenschlager R. Activation of Type I and III Interferon Response by Mitochondrial and Peroxisomal MAVS and Inhibition by Hepatitis C Virus. PLoS Pathog 2015; 11:e1005264. [PMID: 26588843 PMCID: PMC4654527 DOI: 10.1371/journal.ppat.1005264] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 10/19/2015] [Indexed: 12/22/2022] Open
Abstract
Sensing viruses by pattern recognition receptors (PRR) triggers the innate immune system of the host cell and activates immune signaling cascades such as the RIG-I/IRF3 pathway. Mitochondrial antiviral-signaling protein (MAVS, also known as IPS-1, Cardif, and VISA) is the crucial adaptor protein of this pathway localized on mitochondria, peroxisomes and mitochondria-associated membranes of the endoplasmic reticulum. Activation of MAVS leads to the production of type I and type III interferons (IFN) as well as IFN stimulated genes (ISGs). To refine the role of MAVS subcellular localization for the induction of type I and III IFN responses in hepatocytes and its counteraction by the hepatitis C virus (HCV), we generated various functional and genetic knock-out cell systems that were reconstituted to express mitochondrial (mito) or peroxisomal (pex) MAVS, exclusively. Upon infection with diverse RNA viruses we found that cells exclusively expressing pexMAVS mounted sustained expression of type I and III IFNs to levels comparable to cells exclusively expressing mitoMAVS. To determine whether viral counteraction of MAVS is affected by its subcellular localization we employed infection of cells with HCV, a major causative agent of chronic liver disease with a high propensity to establish persistence. This virus efficiently cleaves MAVS via a viral protease residing in its nonstructural protein 3 (NS3) and this strategy is thought to contribute to the high persistence of this virus. We found that both mito- and pexMAVS were efficiently cleaved by NS3 and this cleavage was required to suppress activation of the IFN response. Taken together, our findings indicate comparable activation of the IFN response by pex- and mitoMAVS in hepatocytes and efficient counteraction of both MAVS species by the HCV NS3 protease. Mammalian cells developed several defense mechanisms against viral infection. One major strategy involves pattern recognition receptors (PRRs) recognizing non-self motifs in viral RNA and triggering the production of type I and III interferon (IFN) that induce an antiviral state. One central signaling molecule in this cascade is MAVS (Mitochondrial Antiviral Signaling protein), residing on mitochondria, mitochondria-associated membranes of the endoplasmic reticulum, and peroxisomes. Here we characterized the role of mitochondrial and peroxisomal MAVS for the activation of the IFN response and their counteraction by the hepatitis C virus (HCV), a major causative agent of chronic liver disease with a high propensity to establish persistence. By using various functional and genetic knock-out cell systems reconstituted to express exclusively mitochondrial or peroxisomal MAVS, we observed comparable activation of type I and III IFN response by either MAVS species. In addition, we found that the HCV protease residing in nonstructural protein 3 (NS3) efficiently cleaves MAVS independent from its subcellular localization. This cleavage is required for suppression of the IFN response and might contribute to HCV persistence. Our results indicate a largely localization-independent activation of the IFN response by MAVS in hepatocytes and its efficient counteraction by the HCV NS3 protease.
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Affiliation(s)
- Silke Bender
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Heidelberg, Germany
- Division of Virus-Associated Carcinogenesis, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Antje Reuter
- Division of Virus-Associated Carcinogenesis, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Florian Eberle
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Heidelberg, Germany
| | - Evelyne Einhorn
- Division of Virus-Associated Carcinogenesis, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Master BioSciences, Département de Biologie, École Normale Supérieure de Lyon, Université de Lyon, Lyon, France
| | - Marco Binder
- Division of Virus-Associated Carcinogenesis, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Heidelberg, Germany
- Division of Virus-Associated Carcinogenesis, German Cancer Research Center (DKFZ), Heidelberg, Germany
- * E-mail:
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8
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Targeting and insertion of peroxisomal membrane proteins: ER trafficking versus direct delivery to peroxisomes. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1863:870-80. [PMID: 26392202 DOI: 10.1016/j.bbamcr.2015.09.021] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Revised: 09/11/2015] [Accepted: 09/16/2015] [Indexed: 12/11/2022]
Abstract
The importance of peroxisomes is highlighted by severe inherited human disorders linked to impaired peroxisomal biogenesis. Besides the simple architecture of these ubiquitous and dynamic organelles, their biogenesis is surprisingly complex and involves specialized proteins, termed peroxins, which mediate targeting and insertion of peroxisomal membrane proteins (PMPs) into the peroxisomal bilayer, and the import of soluble proteins into the protein-dense matrix of the organelle. The long-standing paradigm that all peroxisomal proteins are imported directly into preexisting peroxisomes has been challenged by the detection of PMPs inside the endoplasmic reticulum (ER). New models propose that the ER originates peroxisomal biogenesis by mediating PMP trafficking to the peroxisomes via budding vesicles. However, the relative contribution of this ER-derived pathway to the total peroxisome population in vivo, and the detailed mechanisms of ER entry and exit of PMPs are controversially discussed. This review aims to summarize present knowledge about how PMPs are targeted to the ER, instead of being inserted directly into preexisting peroxisomes. Moreover, molecular mechanisms that facilitate bilayer insertion of PMPs among different species are discussed.
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9
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Hua R, Gidda SK, Aranovich A, Mullen RT, Kim PK. Multiple Domains in PEX16 Mediate Its Trafficking and Recruitment of Peroxisomal Proteins to the ER. Traffic 2015; 16:832-52. [PMID: 25903784 DOI: 10.1111/tra.12292] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 04/09/2015] [Accepted: 04/09/2015] [Indexed: 12/27/2022]
Abstract
Peroxisomes rely on a diverse array of mechanisms to ensure the specific targeting of their protein constituents. Peroxisomal membrane proteins (PMPs), for instance, are targeted by at least two distinct pathways: directly to peroxisomes from their sites of synthesis in the cytosol or indirectly via the endoplasmic reticulum (ER). However, the extent to which each PMP targeting pathway is involved in the maintenance of pre-existing peroxisomes is unclear. Recently, we showed that human PEX16 plays a critical role in the ER-dependent targeting of PMPs by mediating the recruitment of two other PMPs, PEX3 and PMP34, to the ER. Here, we extend these results by carrying out a comprehensive mutational analysis of PEX16 aimed at gaining insights into the molecular targeting signals responsible for its ER-to-peroxisome trafficking and the domain(s) involved in PMP recruitment function at the ER. We also show that the recruitment of PMPs to the ER by PEX16 is conserved in plants. The implications of these results in terms of the function of PEX16 and the role of the ER in peroxisome maintenance in general are discussed.
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Affiliation(s)
- Rong Hua
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada M5G 0A4.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada M5G 1A8
| | - Satinder K Gidda
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada N1G 2W1
| | - Alexander Aranovich
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada M5G 0A4
| | - Robert T Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada N1G 2W1
| | - Peter K Kim
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada M5G 0A4.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada M5G 1A8
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Kim PK, Hettema EH. Multiple pathways for protein transport to peroxisomes. J Mol Biol 2015; 427:1176-90. [PMID: 25681696 PMCID: PMC4726662 DOI: 10.1016/j.jmb.2015.02.005] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 02/05/2015] [Accepted: 02/06/2015] [Indexed: 12/15/2022]
Abstract
Peroxisomes are unique among the organelles of the endomembrane system. Unlike other organelles that derive most if not all of their proteins from the ER (endoplasmic reticulum), peroxisomes contain dedicated machineries for import of matrix proteins and insertion of membrane proteins. However, peroxisomes are also able to import a subset of their membrane proteins from the ER. One aspect of peroxisome biology that has remained ill defined is the role the various import pathways play in peroxisome maintenance. In this review, we discuss the available data on matrix and membrane protein import into peroxisomes. Peroxisomal membrane and matrix proteins require distinct factors for their transport. Matrix proteins fold in the cytosol prior to their import. Loaded targeting receptors form part of the matrix protein translocation pore. Many membrane proteins are directly inserted into the peroxisomal membrane. Some peroxisomal membrane proteins are transported via the ER to peroxisomes.
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Affiliation(s)
- P K Kim
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada M5G 1X8; Department of Biochemistry, University of Toronto, Toronto, ON, Canada M5S 1A8
| | - E H Hettema
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, South Yorkshire S10 2TN, United Kingdom.
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Honsho M, Asaoku S, Fukumoto K, Fujiki Y. Topogenesis and homeostasis of fatty acyl-CoA reductase 1. J Biol Chem 2013; 288:34588-98. [PMID: 24108123 DOI: 10.1074/jbc.m113.498345] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Peroxisomal fatty acyl-CoA reductase 1 (Far1) is essential for supplying fatty alcohols required for ether bond formation in ether glycerophospholipid synthesis. The stability of Far1 is regulated by a mechanism that is dependent on cellular plasmalogen levels. However, the membrane topology of Far1 and how Far1 is targeted to membranes remain largely unknown. Here, Far1 is shown to be a peroxisomal tail-anchored protein. The hydrophobic C terminus of Far1 binds to Pex19p, a cytosolic receptor harboring a C-terminal CAAX motif, which is responsible for the targeting of Far1 to peroxisomes. Far1, but not Far2, was preferentially degraded in response to the cellular level of plasmalogens. Experiments in which regions of Far1 or Far2 were replaced with the corresponding region of the other protein showed that the region flanking the transmembrane domain of Far1 is required for plasmalogen-dependent modulation of Far1 stability. Expression of Far1 increased plasmalogen synthesis in wild-type Chinese hamster ovary cells, strongly suggesting that Far1 is a rate-limiting enzyme for plasmalogen synthesis.
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12
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Abstract
PMPs (peroxisome membrane proteins) play essential roles in organelle biogenesis and in co-ordinating peroxisomal metabolism with pathways in other subcellular compartments through transport of metabolites and the operation of redox shuttles. Although the import of soluble proteins into the peroxisome matrix has been well studied, much less is known about the trafficking of PMPs. Pex3 and Pex19 (and Pex16 in mammals) were identified over a decade ago as critical components of PMP import; however, it has proved surprisingly difficult to produce a unified model for their function in PMP import and peroxisome biogenesis. It has become apparent that each of these peroxins has multiple functions and in the present review we focus on both the classical and the more recently identified roles of Pex19 and Pex3 as informed by structural, biochemical and live cell imaging studies. We consider the different models proposed for peroxisome biogenesis and the role of PMP import within them, and propose that the differences may be more perceived than real and may reflect the highly dynamic nature of peroxisomes.
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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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Fujiki Y, Yagita Y, Matsuzaki T. Peroxisome biogenesis disorders: molecular basis for impaired peroxisomal membrane assembly: in metabolic functions and biogenesis of peroxisomes in health and disease. Biochim Biophys Acta Mol Basis Dis 2012; 1822:1337-42. [PMID: 22705440 DOI: 10.1016/j.bbadis.2012.06.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 05/25/2012] [Accepted: 06/06/2012] [Indexed: 11/16/2022]
Abstract
Peroxisome is a single-membrane organelle in eukaryotes. The functional importance of peroxisomes in humans is highlighted by peroxisome-deficient peroxisome biogenesis disorders (PBDs) such as Zellweger syndrome (ZS). Gene defects of peroxins required for both membrane assembly and matrix protein import are identified: ten mammalian pathogenic peroxins for ten complementation groups of PBDs, are required for matrix protein import; three, Pex3p, Pex16p and Pex19p, are shown to be essential for peroxisome membrane assembly and responsible for the most severe ZS in PBDs of three complementation groups 12, 9, and 14, respectively. Patients with severe ZS with defects of PEX3, PEX16, and PEX19 tend to carry severe mutation such as nonsense mutations, frameshifts and deletions. With respect to the function of these three peroxins in membrane biogenesis, two distinct pathways have been proposed for the import of peroxisomal membrane proteins in mammalian cells: a Pex19p- and Pex3p-dependent class I pathway and a Pex19p- and Pex16p-dependent class II pathway. In class II pathway, Pex19p also forms a soluble complex with newly synthesized Pex3p as the chaperone for Pex3p in the cytosol and directly translocates it to peroxisomes. Pex16p functions as the peroxisomal membrane receptor that is specific to the Pex3p-Pex19p complexes. A model for the import of peroxisomal membrane proteins is suggested, providing new insights into the molecular mechanisms underlying the biogenesis of peroxisomes and its regulation involving Pex3p, Pex19p, and Pex16p. Another model suggests that in Saccharomyces cerevisiae peroxisomes likely emerge from the endoplasmic reticulum.
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Affiliation(s)
- Yukio Fujiki
- Department of Biology, Kyushu University Graduate School, Fukuoka, Japan.
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Molecular basis of peroxisomal biogenesis disorders caused by defects in peroxisomal matrix protein import. Biochim Biophys Acta Mol Basis Dis 2012; 1822:1326-36. [PMID: 22617146 DOI: 10.1016/j.bbadis.2012.05.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Revised: 03/26/2012] [Accepted: 05/09/2012] [Indexed: 12/28/2022]
Abstract
Peroxisomal biogenesis disorders (PBDs) represent a spectrum of autosomal recessive metabolic disorders that are collectively characterized by abnormal peroxisome assembly and impaired peroxisomal function. The importance of this ubiquitous organelle for human health is highlighted by the fact that PBDs are multisystemic disorders that often cause death in early infancy. Peroxisomes contribute to central metabolic pathways. Most enzymes in the peroxisomal matrix are linked to lipid metabolism and detoxification of reactive oxygen species. Proper assembly of peroxisomes and thus also import of their enzymes relies on specific peroxisomal biogenesis factors, so called peroxins with PEX being the gene acronym. To date, 13 PEX genes are known to cause PBDs when mutated. Studies of the cellular and molecular defects in cells derived from PBD patients have significantly contributed to the understanding of the functional role of the corresponding peroxins in peroxisome assembly. In this review, we discuss recent data derived from both human cell culture as well as model organisms like yeasts and present an overview on the molecular mechanism underlying peroxisomal biogenesis disorders with emphasis on disorders caused by defects in the peroxisomal matrix protein import machinery.
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Kemp S, Theodoulou FL, Wanders RJA. Mammalian peroxisomal ABC transporters: from endogenous substrates to pathology and clinical significance. Br J Pharmacol 2012; 164:1753-66. [PMID: 21488864 DOI: 10.1111/j.1476-5381.2011.01435.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Peroxisomes are indispensable organelles in higher eukaryotes. They are essential for a number of important metabolic pathways, including fatty acid α- and β-oxidation, and biosynthesis of etherphospholipids and bile acids. However, the peroxisomal membrane forms an impermeable barrier to these metabolites. Therefore, peroxisomes need specific transporter proteins to transfer these metabolites across their membranes. The mammalian peroxisomal membrane harbours three ATP-binding cassette (ABC) transporters. In recent years, significant progress has been made in unravelling the functions of these ABC transporters. There is ample evidence that they are involved in the transport of very long-chain fatty acids, pristanic acid, di- and trihydroxycholestanoic acid, dicarboxylic acids and tetracosahexaenoic acid (C24:6ω3). Surprisingly, only one disease is associated with a deficiency of a peroxisomal ABC transporter. Mutations in the ABCD1 gene encoding the peroxisomal ABC transporter adrenoleukodystrophy protein are the cause for X-linked adrenoleukodystrophy, an inherited metabolic storage disorder. This review describes the current state of knowledge on the mammalian peroxisomal ABC transporters with a particular focus on their function in metabolite transport.
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Affiliation(s)
- Stephan Kemp
- Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.
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Sec16B is involved in the endoplasmic reticulum export of the peroxisomal membrane biogenesis factor peroxin 16 (Pex16) in mammalian cells. Proc Natl Acad Sci U S A 2011; 108:12746-51. [PMID: 21768384 DOI: 10.1073/pnas.1103283108] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sec16 plays a key role in the formation of coat protein II vesicles, which mediate protein transport from the endoplasmic reticulum (ER) to the Golgi apparatus. Mammals have two Sec16 isoforms: Sec16A, which is a longer primary ortholog of yeast Sec16, and Sec16B, which is a shorter distant ortholog. Previous studies have shown that Sec16B, as well as Sec16A, defines ER exit sites, where coat protein II vesicles are formed in mammalian cells. Here, we reveal an unexpected role of Sec16B in the biogenesis of mammalian peroxisomes. When overexpressed, Sec16B was targeted to the entire ER, whereas Sec16A was mostly cytosolic. Concomitant with the overexpression of Sec16B, peroxisomal membrane biogenesis factors peroxin 3 (Pex3) and Pex16 were redistributed from peroxisomes to Sec16B-positive ER membranes. Knockdown of Sec16B but not Sec16A by RNAi affected the morphology of peroxisomes, inhibited the transport of Pex16 from the ER to peroxisomes, and suppressed expression of Pex3. These phenotypes were significantly reversed by the expression of RNAi-resistant Sec16B. Together, our results support the view that peroxisomes are formed, at least partly, from the ER and identify a factor responsible for this process.
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Cell-free sorting of peroxisomal membrane proteins from the endoplasmic reticulum. Proc Natl Acad Sci U S A 2011; 108:9113-8. [PMID: 21576455 DOI: 10.1073/pnas.1018749108] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Several yeast and mammalian peroxisomal membrane proteins (PMPs) are delivered to peroxisomes via the endoplasmic reticulum (ER). Fluorescence microscopy showed a focused assembly of PMPs in a specialized domain of the ER, referred to as the preperoxisomal ER. It is proposed that preperoxisomal vesicles containing PMPs bud from this domain to either fuse with preexisting peroxisomes or to mature into functional peroxisomes by uptake of peroxisomal membrane and matrix proteins. However, such vesicular entities are not identified nor are the biochemical requirements for the budding process known. We developed an in vitro cell-free ER-budding assay using Pichia pastoris and followed two endogenous PMPs, Pex11p and Pex3p during their ER exit. Both the PMPs were copackaged in the ER-budded vesicles that float on a Nycodenz gradient. PMP budding from the ER was dependent on ATP, temperature, cytosol, and Pex19p and generated preperoxisomal vesicles with an incomplete complement of PMPs. Surprisingly, Pex11p budding was independent of Pex3p; however, the budded vesicles were devoid of most of the PMPs otherwise present in the wild-type vesicles and might represent peroxisomal remnants. Our findings provide a biochemical platform to uncover the mechanism of PMP budding from the ER.
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Mast FD, Fagarasanu A, Knoblach B, Rachubinski RA. Peroxisome biogenesis: something old, something new, something borrowed. Physiology (Bethesda) 2011; 25:347-56. [PMID: 21186279 DOI: 10.1152/physiol.00025.2010] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Eukaryotic cells are characterized by their varied complement of organelles. One set of membrane-bound, usually spherical compartments are commonly grouped together under the term peroxisomes. Peroxisomes function in regulating the synthesis and availability of many diverse lipids by harnessing the power of oxidative reactions and contribute to a number of metabolic processes essential for cellular differentiation and organismal development.
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Affiliation(s)
- Fred D Mast
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada
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Rucktäschel R, Girzalsky W, Erdmann R. Protein import machineries of peroxisomes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:892-900. [PMID: 20659419 DOI: 10.1016/j.bbamem.2010.07.020] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 07/19/2010] [Accepted: 07/20/2010] [Indexed: 10/19/2022]
Abstract
Peroxisomes are a class of structurally and functionally related organelles present in almost all eukaryotic cells. The importance of peroxisomes for human life is highlighted by severe inherited diseases which are caused by defects of peroxins, encoded by PEX genes. To date 32 peroxins are known to be involved in different aspects of peroxisome biogenesis. This review addresses two of these aspects, the translocation of soluble proteins into the peroxisomal matrix and the biogenesis of the peroxisomal membrane. This article is part of a Special Issue entitled Protein translocation across or insertion into membranes.
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Affiliation(s)
- Robert Rucktäschel
- Abteilung für Systembiochemie, Institut für Physiologische Chemie, Medizinische Fakultät der Ruhr-Universität Bochum, D-44780 Bochum, Germany
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Rucktäschel R, Halbach A, Girzalsky W, Rottensteiner H, Erdmann R. De novo synthesis of peroxisomes upon mitochondrial targeting of Pex3p. Eur J Cell Biol 2010; 89:947-54. [PMID: 20655617 DOI: 10.1016/j.ejcb.2010.06.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Peroxisomes can form either by growth and division of pre-existing peroxisomes or by de novo synthesis from the endoplasmic reticulum. Pex3p is the key component for both pathways and its targeting to the ER is thought to initiate the de novo formation of peroxisomes. Here, we addressed the question whether Pex3p also can induce peroxisome formation from mitochondrial membranes. Pex3p was targeted to mitochondria by fusion with the mitochondrial targeting signal of Tom20p. The Tom20p-Pex3p-fusion protein was expressed in Pex3p-deficient cells, which are characterized by the lack of peroxisomal membranes. De novo formation of import-competent peroxisomes was observed upon expression of the mitochondrial Pex3p in the mutant cells. This de novo synthesis is independent of the GTPases Vps1p and Dnm1p, two proteins required for peroxisome fission. We conclude that natural or artificial targeting of Pex3p to any endomembrane may initiate peroxisome formation and that also Pex3p-containing mitochondria can serve as source for the de novo synthesis of peroxisomes.
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Affiliation(s)
- Robert Rucktäschel
- Institut für Physiologische Chemie, Abteilung für Systembiochemie, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
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Girzalsky W, Saffian D, Erdmann R. Peroxisomal protein translocation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1803:724-31. [DOI: 10.1016/j.bbamcr.2010.01.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Revised: 12/22/2009] [Accepted: 01/04/2010] [Indexed: 11/30/2022]
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Endoplasmic reticulum-associated secretory proteins Sec20p, Sec39p, and Dsl1p are involved in peroxisome biogenesis. EUKARYOTIC CELL 2009; 8:830-43. [PMID: 19346454 DOI: 10.1128/ec.00024-09] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Two pathways have been identified for peroxisome formation: (i) growth and division and (ii) de novo synthesis. Recent experiments determined that peroxisomes originate at the endoplasmic reticulum (ER). Although many proteins have been implicated in the peroxisome biogenic program, no proteins in the eukaryotic secretory pathway have been identified as having roles in peroxisome formation. Using the yeast Saccharomyces cerevisiae regulatable Tet promoter Hughes clone collection, we found that repression of the ER-associated secretory proteins Sec20p and Sec39p resulted in mislocalization of the peroxisomal matrix protein chimera Pot1p-green fluorescent protein (GFP) to the cytosol. Likewise, the peroxisomal membrane protein chimera Pex3p-GFP localized to tubular-vesicular structures in cells suppressed for Sec20p, Sec39p, and Dsl1p, which form a complex at the ER. Loss of Sec39p attenuated formation of Pex3p-derived peroxisomal structures following galactose induction of Pex3p-GFP expression from the GAL1 promoter. Expression of Sec20p, Sec39p, and Dsl1p was moderately increased in yeast grown under conditions that proliferate peroxisomes, and Sec20p, Sec39p, and Dsl1p were found to cofractionate with peroxisomes and colocalize with Pex3p-monomeric red fluorescent protein under these conditions. Our results show that SEC20, SEC39, and DSL1 are essential secretory genes involved in the early stages of peroxisome assembly, and this work is the first to identify and characterize an ER-associated secretory machinery involved in peroxisome biogenesis.
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Overexpression and purification of rat peroxisomal membrane protein 22, PMP22, in Pichia pastoris. Protein Expr Purif 2009; 64:47-54. [DOI: 10.1016/j.pep.2008.10.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2008] [Revised: 10/09/2008] [Accepted: 10/10/2008] [Indexed: 11/19/2022]
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25
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Liu F, Ng SK, Lu Y, Low W, Lai J, Jedd G. Making two organelles from one: Woronin body biogenesis by peroxisomal protein sorting. ACTA ACUST UNITED AC 2008; 180:325-39. [PMID: 18227279 PMCID: PMC2213590 DOI: 10.1083/jcb.200705049] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Woronin bodies (WBs) are dense-core organelles that are found exclusively in filamentous fungi and that seal the septal pore in response to wounding. These organelles consist of a membrane-bound protein matrix comprised of the HEX protein and, although they form from peroxisomes, their biogenesis is poorly understood. In Neurospora crassa, we identify Woronin sorting complex (WSC), a PMP22/MPV17-related membrane protein with dual functions in WB biogenesis. WSC localizes to large peroxisome membranes where it self-assembles into detergent-resistant oligomers that envelop HEX assemblies, producing asymmetrical nascent WBs. In a reaction requiring WSC, these structures are delivered to the cell cortex, which permits partitioning of the nascent WB and WB inheritance. Our findings suggest that WSC and HEX collaborate and control distinct aspects of WB biogenesis and that cortical association depends on WSC, which in turn depends on HEX. This dependency helps order events across the organellar membrane, permitting the peroxisome to produce a second organelle with a distinct composition and intracellular distribution.
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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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26
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Abstract
Peroxisomes can arise de novo from the endoplasmic reticulum (ER) via a maturation process. Peroxisomes can also multiply by fission. We have investigated how these modes of multiplication contribute to peroxisome numbers in Saccharomyces cerevisiae and the role of the dynamin-related proteins (Drps) in these processes. We have developed pulse-chase and mating assays to follow the fate of existing peroxisomes, de novo–formed peroxisomes, and ER-derived preperoxisomal structures. We find that in wild-type (WT) cells, peroxisomes multiply by fission and do not form de novo. A marker for the maturation pathway, Pex3-GFP, is delivered from the ER to existing peroxisomes. Strikingly, cells lacking peroxisomes as a result of a segregation defect do form peroxisomes de novo. This process is slower than peroxisome multiplication in WT cells and is Drp independent. In contrast, peroxisome fission is Drp dependent. Our results show that peroxisomes multiply by growth and division under our assay conditions. We conclude that the ER to peroxisome pathway functions to supply existing peroxisomes with essential membrane constituents.
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Affiliation(s)
- Alison M Motley
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, England, UK
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Vizeacoumar FJ, Vreden WN, Aitchison JD, Rachubinski RA. Pex19p Binds Pex30p and Pex32p at Regions Required for Their Peroxisomal Localization but Separate from Their Peroxisomal Targeting Signals. J Biol Chem 2006; 281:14805-12. [PMID: 16551610 DOI: 10.1074/jbc.m601808200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The assembly of proteins in the peroxisomal membrane is a multistep process requiring their recognition in the cytosol, targeting to and insertion into the peroxisomal membrane, and stabilization within the lipid bilayer. The peroxin Pex19p has been proposed to be either the receptor that recognizes and targets newly synthesized peroxisomal membrane proteins (PMP) to the peroxisome or a chaperone required for stabilization of PMPs at the peroxisomal membrane. Differentiating between these two roles for Pex19p could be achieved by determining whether the peroxisomal targeting signal (PTS) and the region of Pex19p binding of a PMP are the same or different. We addressed the role for Pex19p in the assembly of two PMPs, Pex30p and Pex32p, of the yeast Saccharomyces cerevisiae. Pex30p and Pex32p control peroxisome size and number but are dispensable for peroxisome formation. Systematic truncations from the carboxyl terminus, together with in-frame deletions of specific regions, have identified PTSs essential for targeting Pex30p and Pex32p to peroxisomes. Both Pex30p and Pex32p interact with Pex19p in regions that do not overlap with their PTSs. However, Pex19p is required for localizing Pex30p and Pex32p to peroxisomes, because mutations that disrupt the interaction of Pex19p with Pex30p and Pex32p lead to their mislocalization to a compartment other than peroxisomes. Mutants of Pex30p and Pex32p that localize to peroxisomes but produce cells exhibiting the peroxisomal phenotypes of cells lacking these proteins demonstrate that the regions in these proteins that control peroxisomal targeting and cell biological activity are separable. Together, our data show that the interaction of Pex19p with Pex30p and Pex32p is required for their roles in peroxisome biogenesis and are consistent with a chaperone role for Pex19p in stabilizing or maintaining membrane proteins in peroxisomes.
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Affiliation(s)
- Franco J Vizeacoumar
- Department of Cell Biology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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Lin-Cereghino GP, Godfrey L, de la Cruz BJ, Johnson S, Khuongsathiene S, Tolstorukov I, Yan M, Lin-Cereghino J, Veenhuis M, Subramani S, Cregg JM. Mxr1p, a key regulator of the methanol utilization pathway and peroxisomal genes in Pichia pastoris. Mol Cell Biol 2006; 26:883-97. [PMID: 16428444 PMCID: PMC1347016 DOI: 10.1128/mcb.26.3.883-897.2006] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2005] [Revised: 07/26/2005] [Accepted: 10/24/2005] [Indexed: 11/20/2022] Open
Abstract
Growth of the yeast Pichia pastoris on methanol induces the expression of genes whose products are required for its metabolism. Three of the methanol pathway enzymes are located in an organelle called the peroxisome. As a result, both methanol pathway enzymes and proteins involved in peroxisome biogenesis (PEX proteins) are induced in response to this substrate. The most highly regulated of these genes is AOX1, which encodes alcohol oxidase, the first enzyme of the methanol pathway, and a peroxisomal enzyme. To elucidate the molecular mechanisms responsible for methanol regulation, we identify genes required for the expression of AOX1. Mutations in one gene, named MXR1 (methanol expression regulator 1), result in strains that are unable to (i) grow on the peroxisomal substrates methanol and oleic acid, (ii) induce the transcription of AOX1 and other methanol pathway and PEX genes, and (iii) form normal-appearing peroxisomes in response to methanol. MXR1 encodes a large protein with a zinc finger DNA-binding domain near its N terminus that has similarity to Saccharomyces cerevisiae Adr1p. In addition, Mxr1p is localized to the nucleus in cells grown on methanol or other gluconeogenic substrates. Finally, Mxr1p specifically binds to sequences upstream of AOX1. We conclude that Mxr1p is a transcription factor that is necessary for the activation of many genes in response to methanol. We propose that MXR1 is the P. pastoris homologue of S. cerevisiae ADR1 but that it has gained new functions and lost others through evolution as a result of changes in the spectrum of genes that it controls.
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Affiliation(s)
- Geoffrey Paul Lin-Cereghino
- Department of Biochemistry and Molecular Biology, Oregon Graduate Institute of Science and Technology, 2000 N.W. Walker Road, Beaverton, Oregon 97006, USA
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Abstract
The abundance and size of cellular organelles vary depending on the cell type and metabolic needs. Peroxisomes constitute a class of cellular organelles renowned for their ability to adapt to cellular and environmental conditions. Together with transcriptional regulators, two groups of peroxisomal proteins have a pronounced influence on peroxisome size and abundance. Pex11-type peroxisome proliferators are involved in the proliferation of peroxisomes, defined here as an increase in size and/or number of peroxisomes. Dynamin-related proteins have recently been suggested to be required for the scission of peroxisomal membranes. This review surveys the function of Pex11-type peroxisome proliferators and dynamin-related proteins in peroxisomal proliferation and division.
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Affiliation(s)
- Sven Thoms
- Ruhr-University-Bochum, Medical Faculty, Institute of Physiological Chemistry, Bochum, Germany
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Abstract
Genetic and proteomic approaches have led to the identification of 32 proteins, collectively called peroxins, which are required for the biogenesis of peroxisomes. Some are responsible for the division and inheritance of peroxisomes; however, most peroxins have been implicated in the topogenesis of peroxisomal proteins. Peroxisomal membrane and matrix proteins are synthesized on free ribosomes in the cytosol and are imported post-translationally into pre-existing organelles (Lazarow PB & Fujiki Y (1985) Annu Rev Cell Biol1, 489-530). Progress has been made in the elucidation of how these proteins are targeted to the organelle. In addition, the understanding of the composition of the peroxisomal import apparatus and the order of events taking place during the cascade of peroxisomal protein import has increased significantly. However, our knowledge on the basic principles of peroxisomal membrane protein insertion or translocation of peroxisomal matrix proteins across the peroxisomal membrane is rather limited. The latter is of particular interest as the peroxisomal import machinery accommodates folded, even oligomeric, proteins, which distinguishes this apparatus from the well characterized translocons of other organelles. Furthermore, the origin of the peroxisomal membrane is still enigmatic. Recent observations suggest the existence of two classes of peroxisomal membrane proteins. Newly synthesized class I proteins are directly targeted to and inserted into the peroxisomal membrane, while class II proteins reach their final destination via the endoplasmic reticulum or a subcompartment thereof, which would be in accord with the idea that the peroxisomal membrane might be derived from the endoplasmic reticulum.
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Affiliation(s)
- Ines Heiland
- Ruhr-Universität Bochum, Institut für Physiologische Chemie, Bochum, Germany
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31
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Kurbatova EM, Dutova TA, Trotsenko YA. Structural, functional and genetic aspects of peroxisome biogenesis. RUSS J GENET+ 2005. [DOI: 10.1007/s11177-005-0032-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Moyersoen J, Choe J, Fan E, Hol WGJ, Michels PAM. Biogenesis of peroxisomes and glycosomes: trypanosomatid glycosome assembly is a promising new drug target. FEMS Microbiol Rev 2005; 28:603-43. [PMID: 15539076 DOI: 10.1016/j.femsre.2004.06.004] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2004] [Revised: 06/14/2004] [Accepted: 06/15/2004] [Indexed: 10/26/2022] Open
Abstract
In trypanosomatids (Trypanosoma and Leishmania), protozoa responsible for serious diseases of mankind in tropical and subtropical countries, core carbohydrate metabolism including glycolysis is compartmentalized in peculiar peroxisomes called glycosomes. Proper biogenesis of these organelles and the correct sequestering of glycolytic enzymes are essential to these parasites. Biogenesis of glycosomes in trypanosomatids and that of peroxisomes in other eukaryotes, including the human host, occur via homologous processes involving proteins called peroxins, which exert their function through multiple, transient interactions with each other. Decreased expression of peroxins leads to death of trypanosomes. Peroxins show only a low level of sequence conservation. Therefore, it seems feasible to design compounds that will prevent interactions of proteins involved in biogenesis of trypanosomatid glycosomes without interfering with peroxisome formation in the human host cells. Such compounds would be suitable as lead drugs against trypanosomatid-borne diseases.
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Affiliation(s)
- Juliette Moyersoen
- Research Unit for Tropical Diseases, Christian de Duve Institute of Cellular Pathology and Laboratory of Biochemistry, Université Catholique de Louvain, ICP-TROP 74.39, Avenue Hippocrate 74, B-1200 Brussels, Belgium
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Wanders RJA, Waterham HR. Peroxisomal disorders I: biochemistry and genetics of peroxisome biogenesis disorders. Clin Genet 2004; 67:107-33. [PMID: 15679822 DOI: 10.1111/j.1399-0004.2004.00329.x] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The peroxisomal disorders represent a group of genetic diseases in humans in which there is an impairment in one or more peroxisomal functions. The peroxisomal disorders are usually subdivided into two subgroups including (i) the peroxisome biogenesis disorders (PBDs) and (ii) the single peroxisomal (enzyme-) protein deficiencies. The PBD group is comprised of four different disorders including Zellweger syndrome (ZS), neonatal adrenoleukodystrophy (NALD), infantile Refsum's disease (IRD), and rhizomelic chondrodysplasia punctata (RCDP). ZS, NALD, and IRD are clearly distinct from RCDP and are usually referred to as the Zellweger spectrum with ZS being the most severe and NALD and IRD the less severe disorders. Studies in the late 1980s had already shown that the PBD group is genetically heterogeneous with at least 12 distinct genetic groups as concluded from complementation studies. Thanks to the much improved knowledge about peroxisome biogenesis notably in yeasts and the successful extrapolation of this knowledge to humans, the genes responsible for all these complementation groups have been identified making molecular diagnosis of PBD patients feasible now. It is the purpose of this review to describe the current stage of knowledge about the clinical, biochemical, cellular, and molecular aspects of PBDs, and to provide guidelines for the post- and prenatal diagnosis of PBDs. Less progress has been made with respect to the pathophysiology and therapy of PBDs. The increasing availability of mouse models for these disorders is a major step forward in this respect.
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Affiliation(s)
- R J A Wanders
- Department of Pediatrics, Academic Medical Centre, Emma Children's Hospital, University of Amsterdam, Amsterdam, The Netherlands.
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Landgraf P, Mayerhofer PU, Polanetz R, Roscher AA, Holzinger A. Targeting of the human adrenoleukodystrophy protein to the peroxisomal membrane by an internal region containing a highly conserved motif. Eur J Cell Biol 2004; 82:401-10. [PMID: 14533738 DOI: 10.1078/0171-9335-00331] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In this study we addressed the targeting requirements of peroxisomal ABC transporters, in particular the human adrenoleukodystrophy protein. This membrane protein is defective or missing in X-linked adrenoleukodystrophy, a neurodegenerative disorder predominantly presenting in childhood. Using adrenoleukodystrophy protein deletion constructs and green fluorescent protein fusion constructs we identified the amino acid regions 1-110 and 67-164 to be sufficient for peroxisomal targeting. However, the minimal region shared by these constructs (amino acids 67-110) is not sufficient for peroxisomal targeting by itself. Additionally, the NH2-terminal 66 amino acids enhance targeting efficiency. Green fluorescent protein-labeled fragments of human peroxisomal membrane protein 69 and Saccharomyces cerevisiae Pxa1 corresponding to the amino acid 67-164 adrenoleukodystrophy protein region were also directed to the mammalian peroxisome. The required region contains a 14-amino-acid motif (71-84) conserved between the adrenoleukodystrophy protein and human peroxisomal membrane protein 69 and yeast Pxa1. Omission or truncation of this motif in the adrenoleukodystrophy protein abolished peroxisomal targeting. The single amino acid substitution L78F resulted in a significant reduction of targeting efficiency. The in-frame deletion of three amino acids (del78-80LLR) within the proposed targeting motif in two patients suffering from X-linked adrenoleukodystrophy resulted in the mislocalization of a green fluorescent protein fusion protein to nucleus, cytosol and mitochondria. Our data define the targeting region of human adrenoleukodystrophy protein containing a highly conserved 14-amino-acid motif.
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Affiliation(s)
- Pablo Landgraf
- Dr. von Hauner Children's Hospital, Department of Clinical Chemistry, Laboratory of Molecular Biology, Ludwig-Maximilians-University Munich, Munich, Germany
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Fang Y, Morrell JC, Jones JM, Gould SJ. PEX3 functions as a PEX19 docking factor in the import of class I peroxisomal membrane proteins. ACTA ACUST UNITED AC 2004; 164:863-75. [PMID: 15007061 PMCID: PMC2172291 DOI: 10.1083/jcb.200311131] [Citation(s) in RCA: 186] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
PEX19 is a chaperone and import receptor for newly synthesized, class I peroxisomal membrane proteins (PMPs). PEX19 binds these PMPs in the cytoplasm and delivers them to the peroxisome for subsequent insertion into the peroxisome membrane, indicating that there may be a PEX19 docking factor in the peroxisome membrane. Here we show that PEX3 is required for PEX19 to dock at peroxisomes, interacts specifically with the docking domain of PEX19, and is required for recruitment of the PEX19 docking domain to peroxisomes. PEX3 is also sufficient to dock PEX19 at heterologous organelles and binds PEX19 via a conserved motif that is essential for this docking activity and for PEX3 function in general. Not surprisingly, transient inhibition of PEX3 abrogates class I PMP import but has no effect on class II PMP import or peroxisomal matrix protein import. Taken together, these results suggest that PEX3 plays a selective, essential, and direct role in PMP import as a docking factor for PEX19.
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Affiliation(s)
- Yi Fang
- Dept. of Biological Chemistry, The Johns Hopkins University School of Medicine, 725 North Wolfe St., Baltimore, MD 21205, USA
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Abstract
Peroxisome biogenesis conceptually consists of the (a) formation of the peroxisomal membrane, (b) import of proteins into the peroxisomal matrix and (c) proliferation of the organelles. Combined genetic and biochemical approaches led to the identification of 25 PEX genes-encoding proteins required for the biogenesis of peroxisomes, so-called peroxins. Peroxisomal matrix and membrane proteins are synthesized on free ribosomes in the cytosol and posttranslationally imported into the organelle in an unknown fashion. The protein import into the peroxisomal matrix and the targeting and insertion of peroxisomal membrane proteins is performed by distinct machineries. At least three peroxins have been shown to be involved in the topogenesis of peroxisomal membrane proteins. Elaborate peroxin complexes form the machinery which in a concerted action of the components transports folded, even oligomeric matrix proteins across the peroxisomal membrane. The past decade has significantly improved our knowledge of the involvement of certain peroxins in the distinct steps of the import process, like cargo recognition, docking of cargo-receptor complexes to the peroxisomal membrane, translocation, and receptor recycling. This review summarizes our knowledge of the functional role the known peroxins play in the biogenesis and maintenance of peroxisomes. Ideas on the involvement of preperoxisomal structures in the biogenesis of the peroxisomal membrane are highlighted and special attention is paid to the concept of cargo protein aggregation as a presupposition for peroxisomal matrix protein import.
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Affiliation(s)
- J H Eckert
- Institut für Physiologische Chemie, Medizinische Fakultät, Ruhr-Universität Bochum, 44780 Bochum, Germany
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Tanaka A, Okumoto K, Fujiki Y. cDNA cloning and characterization of the third isoform of human peroxin Pex11p. Biochem Biophys Res Commun 2003; 300:819-23. [PMID: 12559946 DOI: 10.1016/s0006-291x(02)02936-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have cloned a human cDNA encoding an isoform of the peroxin Pex11p, termed Pex11pgamma, by BLASTP homology search on eukaryotic protein database and reverse transcription (RT)-PCR of human fibroblast RNA. Pex11pgamma was 241 amino-acid long, with two putative transmembrane segments, showing 22% and 23% amino-acid identity to Pex11palpha and Pex11pbeta, respectively. PEX11gamma gene was located on chromosome 19, distinct from PEX11alpha and PEX11beta. Pex11pgamma was found to be a peroxisomal membrane protein, as assessed by colocalization with peroxisome targeting signal type 1 (PTS1)-proteins, in epitope-tagged Pex11pgamma-expressing Chinese hamster ovary cells. Pex11pgamma exposes both of the N- and C-terminal parts to the cytosol. PEX11gamma was not induced in rats by treatment of clofibrate, a peroxisome proliferator, similar to constitutively expressed PEX11beta but in contrast to inducible PEX11alpha.
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Affiliation(s)
- Atsushi Tanaka
- Department of Biology, Faculty of Sciences, Kyushu University Graduate School, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
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38
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Faber KN, Haan GJ, Baerends RJS, Kram AM, Veenhuis M. Normal peroxisome development from vesicles induced by truncated Hansenula polymorpha Pex3p. J Biol Chem 2002; 277:11026-33. [PMID: 11790797 DOI: 10.1074/jbc.m112347200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We show that the synthesis of the N-terminal 50 amino acids of Pex3p (Pex3p(1-50)) in Hansenula polymorpha pex3 cells is associated with the formation of vesicular membrane structures. Biochemical and ultrastructural findings suggest that the nuclear membrane is the donor membrane compartment of these vesicles. These structures also contain Pex14p and can develop into functional peroxisomes after subsequent reintroduction of the full-length Pex3p protein. We discuss the significance of this finding in relation to peroxisome reintroduction, e.g. in case peroxisomes are lost due to failure in inheritance.
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Affiliation(s)
- Klaas Nico Faber
- Eukaryotic Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Postbus 14, 9750 AA Haren, The Netherlands.
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39
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Cowman AF, Baldi DL, Duraisingh M, Healer J, Mills KE, O'Donnell RA, Thompson J, Triglia T, Wickham ME, Crabb BS. Functional analysis of Plasmodium falciparum merozoite antigens: implications for erythrocyte invasion and vaccine development. Philos Trans R Soc Lond B Biol Sci 2002; 357:25-33. [PMID: 11839179 PMCID: PMC1692917 DOI: 10.1098/rstb.2001.1010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Malaria is a major human health problem and is responsible for over 2 million deaths per year. It is caused by a number of species of the genus Plasmodium, and Plasmodium falciparum is the causative agent of the most lethal form. Consequently, the development of a vaccine against this parasite is a priority. There are a number of stages of the parasite life cycle that are being targeted for the development of vaccines. Important candidate antigens include proteins on the surface of the asexual merozoite stage, the form that invades the host erythrocyte. The development of methods to manipulate the genome of Plasmodium species has enabled the construction of gain-of-function and loss-of-function mutants and provided new strategies to analyse the role of parasite proteins. This has provided new information on the role of merozoite antigens in erythrocyte invasion and also allows new approaches to address their potential as vaccine candidates.
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Affiliation(s)
- Alan F Cowman
- The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria 3050, Australia.
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40
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Brosius U, Dehmel T, Gärtner J. Two different targeting signals direct human peroxisomal membrane protein 22 to peroxisomes. J Biol Chem 2002; 277:774-84. [PMID: 11590176 DOI: 10.1074/jbc.m108155200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The 22-kDa peroxisomal membrane protein (PMP22) is a major component of peroxisomal membranes in mammals. Although its precise role in peroxisome function is poorly understood, it seems to be involved in pore forming activity and may contribute to the unspecific permeability of the organelle membrane. PMP22 is synthesized on free cytosolic ribosomes and then directed to the peroxisome membrane by specific targeting information. Previous studies in rats revealed that PMP22 contains one distinct peroxisomal membrane targeting signal in the amino-terminal cytoplasmic tail. We cloned and characterized the targeting signal of human PMP22 and compared it with the already described characteristics of the corresponding rat protein. Amino acid sequence alignment of rat and human protein revealed 77% identity including a high conservation of several protein motifs. We expressed various deletion constructs of PMP22 in fusion with the green fluorescent protein in COS-7 cells and determined their intracellular localization. In contrast to previous studies on rat PMP22 and most other peroxisomal membrane proteins, we showed that human as well as rat PMP22 contains two distinct and nonoverlapping peroxisomal membrane targeting signals, one in the amino-terminal and the other in the carboxyl-terminal protein region. They consist of two transmembrane domains and adjacent protein loops with almost identical basic clusters. Both of these peroxisomal targeting regions interact with PEX19, a factor required for peroxisome membrane synthesis. In addition, we observed that fusing the green fluorescent protein immediately adjacent to the targeting region completely abolishes targeting function and mislocalizes PMP22 to the cytosol.
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Affiliation(s)
- Ute Brosius
- Department of Pediatrics, Heinrich Heine University, Düsseldorf D-40225, Germany
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41
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Cell-free synthesis of alkaline lipase, a glyoxysomal membrane protein, from castor bean endosperm. FEBS Lett 2001. [DOI: 10.1016/0014-5793(87)80868-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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42
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South ST, Baumgart E, Gould SJ. Inactivation of the endoplasmic reticulum protein translocation factor, Sec61p, or its homolog, Ssh1p, does not affect peroxisome biogenesis. Proc Natl Acad Sci U S A 2001; 98:12027-31. [PMID: 11593013 PMCID: PMC59761 DOI: 10.1073/pnas.221289498] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2001] [Indexed: 11/18/2022] Open
Abstract
Peroxisomes are single membrane-bound organelles present in virtually all eukaryotes. These organelles participate in several important metabolic processes, and defects in peroxisome function and biogenesis are a significant contributor to human disease. Several models propose that peroxisomes arise from the endoplasmic reticulum (ER) in a process that involves the translocation of "group I" peroxisomal membrane proteins into the ER, the exit of these group I peroxisomal membrane proteins from the ER by vesicle budding, and the formation of nascent peroxisomes from vesicles containing the group I peroxisomal membrane proteins. A central prediction of these models is that the formation of nascent peroxisomes requires protein translocation into the ER. Sec61p is an essential component of the ER translocon, and we show here that loss of Sec61p activity has no effect on peroxisome biogenesis. In addition, loss of the SEC61-related gene, SSH1, also has no effect on peroxisome biogenesis. Although some proteins may enter the ER independently of Sec61p or Ssh1p, none are known, leading us to propose that peroxisome biogenesis may not require protein import into the ER, and by extension, transfer of proteins from the ER to the peroxisome.
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Affiliation(s)
- S T South
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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43
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Jones JM, Morrell JC, Gould SJ. Multiple distinct targeting signals in integral peroxisomal membrane proteins. J Cell Biol 2001; 153:1141-50. [PMID: 11402059 PMCID: PMC2192020 DOI: 10.1083/jcb.153.6.1141] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2000] [Accepted: 04/24/2001] [Indexed: 12/05/2022] Open
Abstract
Peroxisomal proteins are synthesized on free polysomes and then transported from the cytoplasm to peroxisomes. This process is mediated by two short well-defined targeting signals in peroxisomal matrix proteins, but a well-defined targeting signal has not yet been described for peroxisomal membrane proteins (PMPs). One assumption in virtually all prior studies of PMP targeting is that a given protein contains one, and only one, distinct targeting signal. Here, we show that the metabolite transporter PMP34, an integral PMP, contains at least two nonoverlapping sets of targeting information, either of which is sufficient for insertion into the peroxisome membrane. We also show that another integral PMP, the peroxin PEX13, also contains two independent sets of peroxisomal targeting information. These results challenge a major assumption of most PMP targeting studies. In addition, we demonstrate that PEX19, a factor required for peroxisomal membrane biogenesis, interacts with the two minimal targeting regions of PMP34. Together, these results raise the interesting possibility that PMP import may require novel mechanisms to ensure the solubility of integral PMPs before their insertion in the peroxisome membrane, and that PEX19 may play a central role in this process.
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Affiliation(s)
- Jacob M. Jones
- The Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - James C. Morrell
- The Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Stephen J. Gould
- The Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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Iida R, Yasuda T, Tsubota E, Matsuki T, Kishi K. Cloning, mapping, genomic organization, and expression of mouse M-LP, a new member of the peroxisomal membrane protein Mpv17 domain family. Biochem Biophys Res Commun 2001; 283:292-6. [PMID: 11327696 DOI: 10.1006/bbrc.2001.4769] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have identified a mouse full-length cDNA and gene encoding a novel protein (M-LP), based on an expressed sequence tag (EST) sequence (GenBank Accession No. AI482564) obtained by differential display screening of age-dependently expressed genes in mouse kidney. The ML-P gene is composed of three exons, ranges over 5 kb on mouse chromosome 16B1-B2 and is expressed as two transcripts (1455 and 3058 bp), both of which include the same open-reading frame encoding 194 amino acids. M-LP is expressed mainly in kidney and spleen and shows age-dependent expression. M-LP has sequence homologies and membrane topologies very similar to the Mpv17 protein, a peroxisomal protein involved in the development of early-onset glomerulosclerosis. Search of the protein domain family database (ProDom) revealed that M-LP is a new member of the Mpv17 domain family (PD008400).
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Affiliation(s)
- R Iida
- Department of Forensic Medicine, Fukui Medical University, Matsuoka-cho, Fukui, 910-1193, Japan.
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45
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Honsho M, Fujiki Y. Topogenesis of peroxisomal membrane protein requires a short, positively charged intervening-loop sequence and flanking hydrophobic segments. study using human membrane protein PMP34. J Biol Chem 2001; 276:9375-82. [PMID: 11121399 DOI: 10.1074/jbc.m003304200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human 34-kDa peroxisomal membrane protein (PMP34) consisting of 307 amino acids was previously identified as an ortholog of, or a similar protein (with 27% identity) to the, 423-amino acid-long PMP47 of the yeast Candida boidinii. We investigated membrane topogenesis of PMP34 with six putative transmembrane segments, as a model peroxisomal membrane protein. PMP34 was characterized as an integral membrane protein of peroxisomes. Transmembrane topology of PMP34 was determined by differential permeabilization and immunofluorescent staining of HeLa cells ectopically expressing PMP34 as well as of Chinese hamster ovary-K1 expressing epitope-tagged PMP34. As opposed to PMP47, PMP34 was found to expose its N- and C-terminal parts to the cytosol. Various deletion variants of PMP34 and their fusion proteins with green fluorescent protein were expressed in Chinese hamster ovary-K1 and were verified with respect to intracellular localization. The loop region between transmembrane segments 4 and 5 was required for the peroxisome-targeting activity, in which Ala substitution for basic residues abrogated the activity. Three hydrophobic transmembrane segments linked in a flanking region of the basic loop were essential for integration of PMP34 to peroxisome membranes. Therefore, it is evident that the intervening basic loop plus three transmembrane segments of PMP34 function as a peroxisomal targeting and topogenic signal.
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Affiliation(s)
- M Honsho
- Department of Biology, Faculty of Sciences, Kyushu University Graduate School, Fukuoka 812-8581, Japan
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46
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Abstract
The segregation of metabolic functions within discrete organelles is a hallmark of eukaryotic cells. These compartments allow for the concentration of related metabolic functions, the separation of competing metabolic functions, and the formation of unique chemical microenvironments. However, such organization is not spontaneous and requires an array of genes that are dedicated to the assembly and maintenance of these structures. In this review we focus on the genetics of peroxisome biogenesis and on how defects in this process cause human disease.
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Affiliation(s)
- K A Sacksteder
- Department of Biological Chemistry, the Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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47
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Wilcke M, Alexson SE. Differential induction of peroxisomal populations in subcellular fractions of rat liver. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1544:358-69. [PMID: 11341945 DOI: 10.1016/s0167-4838(00)00250-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
In rat liver, peroxisome proliferators induce profound changes in the number and protein composition of peroxisomes, which upon subcellular fractionation is reflected in heterogeneity in sedimentation properties of peroxisome populations. In this study we have investigated the time course of induction of the peroxisomal proteins catalase, acyl-CoA oxidase (ACO) and the 70 kDa peroxisomal membrane protein (PMP70) in different subcellular fractions. Rats were fed a di(2-ethylhexyl)phthalate (DEHP) containing diet for 8 days and livers were removed at different time-points, fractionated by differential centrifugation into nuclear, heavy and light mitochondrial, microsomal and soluble fractions, and organelle marker enzymes were measured. Catalase was enriched mainly in the light mitochondrial and soluble fractions, while ACO was enriched in the nuclear fraction (about 30%) and in the soluble fraction. PMP70 was found in all fractions except the soluble fraction. DEHP treatment induced ACO, catalase and PMP70 activity and immunoreactive protein, but the time course and extent of induction was markedly different in the various subcellular fractions. All three proteins were induced more rapidly in the nuclear fraction than in the light mitochondrial or microsomal fractions, with catalase and PMP70 being maximally induced in the nuclear fraction already at 2 days of treatment. Refeeding a normal diet quickly normalized most parameters. These results suggest that induction of a heavy peroxisomal compartment is an early event and that induction of 'small peroxisomes', containing PMP70 and ACO, is a late event. These data are compatible with a model where peroxisomes initially proliferate by growth of a heavy, possibly reticular-like, structure rather than formation of peroxisomes by division of pre-existing organelles into small peroxisomes that subsequently grow. The various peroxisome populations that can be separated by subcellular fractionation may represent peroxisomes at different stages of biogenesis.
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Affiliation(s)
- M Wilcke
- The Wenner-Gren Institute, Stockholm University, Sweden.
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48
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Baerends RJ, Faber KN, Kiel JA, van der Klei IJ, Harder W, Veenhuis M. Sorting and function of peroxisomal membrane proteins. FEMS Microbiol Rev 2000; 24:291-301. [PMID: 10841974 DOI: 10.1111/j.1574-6976.2000.tb00543.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Peroxisomes are subcellular organelles and are present in virtually all eukaryotic cells. Characteristic features of these organelles are their inducibility and their functional versatility. Their importance in the intermediary metabolism of cells is exemplified by the discovery of several inborn, fatal peroxisomal errors in man, the so-called peroxisomal disorders. Recent findings in research on peroxisome biogenesis and function have demonstrated that peroxisomal matrix proteins and peroxisomal membrane proteins (PMPs) follow separate pathways to reach their target organelle. This paper addresses the principles of PMP sorting and summarizes the current knowledge of the role of these proteins in organelle biogenesis and function.
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Affiliation(s)
- R J Baerends
- Eukaryotic Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, Postbus 14, 9750 AA, Haren, The Netherlands
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49
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South ST, Sacksteder KA, Li X, Liu Y, Gould SJ. Inhibitors of COPI and COPII do not block PEX3-mediated peroxisome synthesis. J Cell Biol 2000; 149:1345-60. [PMID: 10871277 PMCID: PMC2175136 DOI: 10.1083/jcb.149.7.1345] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2000] [Accepted: 05/18/2000] [Indexed: 12/11/2022] Open
Abstract
In humans, defects in peroxisome biogenesis are the cause of lethal diseases typified by Zellweger syndrome. Here, we show that inactivating mutations in human PEX3 cause Zellweger syndrome, abrogate peroxisome membrane synthesis, and result in reduced abundance of peroxisomal membrane proteins (PMPs) and/or mislocalization of PMPs to the mitochondria. Previous studies have suggested that PEX3 may traffic through the ER en route to the peroxisome, that the COPI inhibitor, brefeldin A, leads to accumulation of PEX3 in the ER, and that PEX3 overexpression alters the morphology of the ER. However, we were unable to detect PEX3 in the ER at early times after expression. Furthermore, we find that inhibition of COPI function by brefeldin A has no effect on trafficking of PEX3 to peroxisomes and does not inhibit PEX3-mediated peroxisome biogenesis. We also find that inhibition of COPII-dependent membrane traffic by a dominant negative SAR1 mutant fails to block PEX3 transport to peroxisomes and PEX3-mediated peroxisome synthesis. Based on these results, we propose that PEX3 targeting to peroxisomes and PEX3-mediated peroxisome membrane synthesis may occur independently of COPI- and COPII-dependent membrane traffic.
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Affiliation(s)
- Sarah T. South
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Katherine A. Sacksteder
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Xiaoling Li
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Yifei Liu
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Stephen J. Gould
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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50
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Ghaedi K, Tamura S, Okumoto K, Matsuzono Y, Fujiki Y. The peroxin pex3p initiates membrane assembly in peroxisome biogenesis. Mol Biol Cell 2000; 11:2085-102. [PMID: 10848631 PMCID: PMC14905 DOI: 10.1091/mbc.11.6.2085] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Rat cDNA encoding a 372-amino-acid peroxin was isolated, primarily by functional complementation screening, using a peroxisome-deficient Chinese hamster ovary cell mutant, ZPG208, of complementation group 17. The deduced primary sequence showed approximately 25% amino acid identity with the yeast Pex3p, thereby we termed this cDNA rat PEX3 (RnPEX3). Human and Chinese hamster Pex3p showed 96 and 94% identity to rat Pex3p and had 373 amino acids. Pex3p was characterized as an integral membrane protein of peroxisomes, exposing its N- and C-terminal parts to the cytosol. A homozygous, inactivating missense mutation, G to A at position413, in a codon (GGA) for Gly(138) and resulting in a codon (GAA) for Glu was the genetic cause of peroxisome deficiency of complementation group 17 ZPG208. The peroxisome-restoring activity apparently required the full length of Pex3p, whereas its N-terminal part from residues 1 to 40 was sufficient to target a fusion protein to peroxisomes. We also demonstrated that Pex3p binds the farnesylated peroxisomal membrane protein Pex19p. Moreover, upon expression of PEX3 in ZPG208, peroxisomal membrane vesicles were assembled before the import of soluble proteins such as PTS2-tagged green fluorescent protein. Thus, Pex3p assembles membrane vesicles before the matrix proteins are translocated.
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Affiliation(s)
- K Ghaedi
- Department of Biology, Graduate School of Science, Kyushu University, Fukuoka 812-8581, Japan
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