1
|
Pedersen MP, Wolters JC, de Boer R, Krikken AM, van der Klei IJ. The Hansenula polymorpha mitochondrial carrier family protein Mir1 is dually localized at peroxisomes and mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119742. [PMID: 38702017 DOI: 10.1016/j.bbamcr.2024.119742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 04/19/2024] [Accepted: 04/25/2024] [Indexed: 05/06/2024]
Abstract
Peroxisomes are ubiquitous cell organelles involved in various metabolic pathways. In order to properly function, several cofactors, substrates and products of peroxisomal enzymes need to pass the organellar membrane. So far only a few transporter proteins have been identified. We analysed peroxisomal membrane fractions purified from the yeast Hansenula polymorpha by untargeted label-free quantitation mass spectrometry. As expected, several known peroxisome-associated proteins were enriched in the peroxisomal membrane fraction. In addition, several other proteins were enriched, including mitochondrial transport proteins. Localization studies revealed that one of them, the mitochondrial phosphate carrier Mir1, has a dual localization on mitochondria and peroxisomes. To better understand the molecular mechanisms of dual sorting, we localized Mir1 in cells lacking Pex3 or Pex19, two peroxins that play a role in targeting of peroxisomal membrane proteins. In these cells Mir1 only localized to mitochondria, indicating that Pex3 and Pex19 are required to sort Mir1 to peroxisomes. Analysis of the localization of truncated versions of Mir1 in wild-type H. polymorpha cells revealed that most of them localized to mitochondria, but only one, consisting of the transmembrane domains 3-6, was peroxisomal. Peroxisomal localization of this construct was lost in a MIR1 deletion strain, indicating that full-length Mir1 was required for the localization of the truncated protein to peroxisomes. Our data suggest that only full-length Mir1 sorts to peroxisomes, while Mir1 contains multiple regions with mitochondrial sorting information. Data are available via ProteomeXchange with identifier PXD050324.
Collapse
Affiliation(s)
- Marc Pilegaard Pedersen
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
| | - Justina C Wolters
- Laboratory of Pediatrics, Section Systems Medicine of Metabolism and Signaling, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Rinse de Boer
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
| | - Arjen M Krikken
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
| | - Ida J van der Klei
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands.
| |
Collapse
|
2
|
Skowyra ML, Feng P, Rapoport TA. Towards solving the mystery of peroxisomal matrix protein import. Trends Cell Biol 2024; 34:388-405. [PMID: 37743160 PMCID: PMC10957506 DOI: 10.1016/j.tcb.2023.08.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 08/21/2023] [Accepted: 08/25/2023] [Indexed: 09/26/2023]
Abstract
Peroxisomes are vital metabolic organelles that import their lumenal (matrix) enzymes from the cytosol using mobile receptors. Surprisingly, the receptors can even import folded proteins, but the underlying mechanism has been a mystery. Recent results reveal how import receptors shuttle cargo into peroxisomes. The cargo-bound receptors move from the cytosol across the peroxisomal membrane completely into the matrix by a mechanism that resembles transport through the nuclear pore. The receptors then return to the cytosol through a separate retrotranslocation channel, leaving the cargo inside the organelle. This cycle concentrates imported proteins within peroxisomes, and the energy for cargo import is supplied by receptor export. Peroxisomal protein import thus fundamentally differs from other previously known mechanisms for translocating proteins across membranes.
Collapse
Affiliation(s)
- Michael L Skowyra
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Peiqiang Feng
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Tom A Rapoport
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
| |
Collapse
|
3
|
Kunze M. The type-2 peroxisomal targeting signal. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1867:118609. [PMID: 31751594 DOI: 10.1016/j.bbamcr.2019.118609] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Revised: 11/08/2019] [Accepted: 11/13/2019] [Indexed: 12/13/2022]
Abstract
The type-2 peroxisomal targeting signal (PTS2) is one of two peptide motifs destining soluble proteins for peroxisomes. This signal acts as amphiphilic α-helix exposing the side chains of all conserved residues to the same side. PTS2 motifs are recognized by a bipartite protein complex consisting of the receptor PEX7 and a co-receptor. Cargo-loaded receptor complexes are translocated across the peroxisomal membrane by a transient pore and inside peroxisomes, cargo proteins are released and processed in many, but not all species. The components of the bipartite receptor are re-exported into the cytosol by a ubiquitin-mediated and ATP-driven export mechanism. Structurally, PTS2 motifs resemble other N-terminal targeting signals, whereas the functional relation to the second peroxisomal targeting signal (PTS1) is unclear. Although only a few PTS2-carrying proteins are known in humans, subjects lacking a functional import mechanism for these proteins suffer from the severe inherited disease rhizomelic chondrodysplasia punctata.
Collapse
Affiliation(s)
- Markus Kunze
- Medical University of Vienna, Center for Brain Research, Department of Pathobiology of the Nervous System, Spitalgasse 4, 1090 Vienna, Austria.
| |
Collapse
|
4
|
Abstract
Peroxisomes carry out various oxidative reactions that are tightly regulated to adapt to the changing needs of the cell and varying external environments. Accordingly, they are remarkably fluid and can change dramatically in abundance, size, shape and content in response to numerous cues. These dynamics are controlled by multiple aspects of peroxisome biogenesis that are coordinately regulated with each other and with other cellular processes. Ongoing studies are deciphering the diverse molecular mechanisms that underlie biogenesis and how they cooperate to dynamically control peroxisome utility. These important challenges should lead to an understanding of peroxisome dynamics that can be capitalized upon for bioengineering and the development of therapies to improve human health.
Collapse
Affiliation(s)
- Jennifer J Smith
- 1] Seattle Biomedical Research Institute, 307 Westlake Avenue North, 98109-5240, USA. [2] Institute for Systems Biology, 401 Terry Avenue North, Seattle, Washington 98109-5219, USA
| | | |
Collapse
|
5
|
Deckers M, Emmrich K, Girzalsky W, Awa WL, Kunau WH, Erdmann R. Targeting of Pex8p to the peroxisomal importomer. Eur J Cell Biol 2010; 89:924-31. [DOI: 10.1016/j.ejcb.2010.06.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
|
6
|
Kashiwayama Y, Asahina K, Morita M, Imanaka T. Hydrophobic Regions Adjacent to Transmembrane Domains 1 and 5 Are Important for the Targeting of the 70-kDa Peroxisomal Membrane Protein. J Biol Chem 2007; 282:33831-33844. [PMID: 17761678 DOI: 10.1074/jbc.m703369200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The 70-kDa peroxisomal membrane protein (PMP70) is a major component of peroxisomal membranes. Human PMP70 consists of 659 amino acid residues and has six putative transmembrane domains (TMDs). PMP70 is synthesized on cytoplasmic ribosomes and targeted posttranslationally to peroxisomes by an unidentified peroxisomal membrane protein targeting signal (mPTS). In this study, to examine the mPTS within PMP70 precisely, we expressed various COOH-terminally or NH(2)-terminally deleted constructs of PMP70 fused with green fluorescent protein (GFP) in Chinese hamster ovary cells and determined their intracellular localization by immunofluorescence. In the COOH-terminally truncated PMP70, PMP70(AA.1-144)-GFP, including TMD1 and TMD2 of PMP70, was still localized to peroxisomes. However, by further removal of TMD2, PMP70(AA.1-124)-GFP lost the targeting ability, and PMP70(TMD2)-GFP did not target to peroxisomes by itself. The substitution of TMD2 in PMP70(AA.1-144)-GFP for TMD4 or TMD6 did not affect the peroxisomal localization, suggesting that PMP70(AA.1-124) contains the mPTS and an additional TMD is required for the insertion into the peroxisomal membrane. In the NH(2)-terminal 124-amino acid region, PMP70 possesses hydrophobic segments in the region adjacent to TMD1. By the disruption of these hydrophobic motifs by the mutation of L21Q/L22Q/L23Q or I70N/L71Q, PMP70(AA.1-144)-GFP lost targeting efficiency. The NH(2)-terminally truncated PMP70, GFP-PMP70(AA.263-375), including TMD5 and TMD6, exhibited the peroxisomal localization. PMP70(AA.263-375) also possesses hydrophobic residues (Ile(307)/Leu(308)) in the region adjacent to TMD5, which were important for targeting. These results suggest that PMP70 possesses two distinct targeting signals, and hydrophobic regions adjacent to the first TMD of each region are important for targeting.
Collapse
Affiliation(s)
- Yoshinori Kashiwayama
- Department of Biological Chemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Kota Asahina
- Department of Biological Chemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Masashi Morita
- Department of Biological Chemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Tsuneo Imanaka
- Department of Biological Chemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
| |
Collapse
|
7
|
van der Klei IJ, Veenhuis M. PTS1-independent sorting of peroxisomal matrix proteins by Pex5p. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1763:1794-800. [PMID: 17005270 DOI: 10.1016/j.bbamcr.2006.08.013] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2006] [Revised: 07/27/2006] [Accepted: 08/18/2006] [Indexed: 10/24/2022]
Abstract
Most peroxisomal matrix proteins contain a peroxisomal targeting signal 1 (PTS1) for sorting to the correct organelle. This signal is located at the extreme C-terminus and generally consists of only three amino acids. The PTS1 is recognized by the receptor protein Pex5p. Several examples have been reported of peroxisomal matrix proteins that are sorted to peroxisomes via Pex5p, but lack a typical PTS1 tripeptide. In this contribution we present an overview of these so-called non-PTS1 proteins and discuss the current knowledge of the molecular mechanisms involved in their sorting.
Collapse
Affiliation(s)
- Ida J van der Klei
- Eukaryotic Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, The Netherlands.
| | | |
Collapse
|
8
|
Mullen RT, Trelease RN. The ER-peroxisome connection in plants: Development of the “ER semi-autonomous peroxisome maturation and replication” model for plant peroxisome biogenesis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:1655-68. [PMID: 17049631 DOI: 10.1016/j.bbamcr.2006.09.011] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2006] [Revised: 08/25/2006] [Accepted: 09/06/2006] [Indexed: 10/24/2022]
Abstract
The perceived role of the ER in the biogenesis of plant peroxisomes has evolved significantly from the original "ER vesiculation" model, which portrayed co-translational import of proteins into peroxisomes originating from the ER, to the "ER semi-autonomous peroxisome" model wherein membrane lipids and post-translationally acquired peroxisomal membrane proteins (PMPs) were derived from the ER. Results from more recent studies of various plant PMPs including ascorbate peroxidase, PEX10 and PEX16, as well as a viral replication protein, have since led to the formulation of a more elaborate "ER semi-autonomous peroxisome maturation and replication" model. Herein we review these results in the context of this newly proposed model and its predecessor models. We discuss also key distinct features of the new model pertaining to its central premise that the ER defines the semi-autonomous maturation (maintenance/assembly/differentiation) and duplication (division) features of specialized classes of pre-existing plant peroxisomes. This model also includes a novel peroxisome-to-ER retrograde sorting pathway that may serve as a constitutive protein retrieval/regulatory system. In addition, new plant peroxisomes are envisaged to arise primarily by duplication of the pre-existing peroxisomes that receive essential membrane components from the ER.
Collapse
Affiliation(s)
- Robert T Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada N1G 2W1.
| | | |
Collapse
|
9
|
Van Ael E, Fransen M. Targeting signals in peroxisomal membrane proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:1629-38. [PMID: 17020786 DOI: 10.1016/j.bbamcr.2006.08.020] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2006] [Revised: 08/17/2006] [Accepted: 08/18/2006] [Indexed: 10/24/2022]
Abstract
Peroxisomal membrane proteins (PMPs) are encoded by the nuclear genome and translated on cytoplasmic ribosomes. Newly synthesized PMPs can be targeted directly from the cytoplasm to peroxisomes or travel to peroxisomes via the endoplasmic reticulum (ER). The mechanisms responsible for the targeting of these proteins to the peroxisomal membrane are still rather poorly understood. However, it is clear that the trafficking of PMPs to peroxisomes depends on the presence of cis-acting targeting signals, called mPTSs. These mPTSs show great variability both in the identity and number of requisite residues. An emerging view is that mPTSs consist of at least two functionally distinct domains: a targeting element, which directs the newly synthesized PMP from the cytoplasm to its target membrane, and a membrane-anchoring sequence, which is required for the permanent insertion of the protein into the peroxisomal membrane. In this review, we summarize our knowledge of the mPTSs currently identified.
Collapse
Affiliation(s)
- Elke Van Ael
- Katholieke Universiteit Leuven, Faculty of Medicine, Department of Molecular Cell Biology, Division of Pharmacology, Campus Gasthuisberg, Herestraat 49 bus 601, 3000 Leuven, Belgium
| | | |
Collapse
|
10
|
Titorenko VI, Mullen RT. Peroxisome biogenesis: the peroxisomal endomembrane system and the role of the ER. ACTA ACUST UNITED AC 2006; 174:11-7. [PMID: 16801391 PMCID: PMC2064154 DOI: 10.1083/jcb.200604036] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Peroxisomes have long been viewed as semiautonomous, static, and homogenous organelles that exist outside the secretory and endocytic pathways of vesicular flow. However, growing evidence supports the view that peroxisomes actually constitute a dynamic endomembrane system that originates from the endoplasmic reticulum. This review highlights the various strategies used by evolutionarily diverse organisms for coordinating the flow of membrane-enclosed carriers through the peroxisomal endomembrane system and critically evaluates the dynamics and molecular mechanisms of this multistep process.
Collapse
|
11
|
Binns D, Januszewski T, Chen Y, Hill J, Markin VS, Zhao Y, Gilpin C, Chapman KD, Anderson RGW, Goodman JM. An intimate collaboration between peroxisomes and lipid bodies. ACTA ACUST UNITED AC 2006; 173:719-31. [PMID: 16735577 PMCID: PMC2063889 DOI: 10.1083/jcb.200511125] [Citation(s) in RCA: 278] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although peroxisomes oxidize lipids, the metabolism of lipid bodies and peroxisomes is thought to be largely uncoupled from one another. In this study, using oleic acid-cultured Saccharomyces cerevisiae as a model system, we provide evidence that lipid bodies and peroxisomes have a close physiological relationship. Peroxisomes adhere stably to lipid bodies, and they can even extend processes into lipid body cores. Biochemical experiments and proteomic analysis of the purified lipid bodies suggest that these processes are limited to enzymes of fatty acid beta oxidation. Peroxisomes that are unable to oxidize fatty acids promote novel structures within lipid bodies ("gnarls"), which may be organized arrays of accumulated free fatty acids. However, gnarls are suppressed, and fatty acids are not accumulated in the absence of peroxisomal membranes. Our results suggest that the extensive physical contact between peroxisomes and lipid bodies promotes the coupling of lipolysis within lipid bodies with peroxisomal fatty acid oxidation.
Collapse
Affiliation(s)
- Derk Binns
- Department of Pharmacology, University of Texas Southwestern Medical School, Dallas, TX 75390, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
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.
Collapse
Affiliation(s)
- Franco J Vizeacoumar
- Department of Cell Biology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | | | | | | |
Collapse
|
13
|
Mullen RT, McCartney AW, Flynn CR, Smith GS. Peroxisome biogenesis and the formation of multivesicular peroxisomes during tombusvirus infection: a role for ESCRT?This review is one of a selection of papers published in the Special Issue on Plant Cell Biology. ACTA ACUST UNITED AC 2006. [DOI: 10.1139/b06-005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Peroxisomes are highly dynamic organelles with regard to their metabolic functions, shapes, distribution, movements, and biogenesis. They are also important as sites for the development of some viral pathogens. It has long been known that certain members of the tombusvirus family recruit peroxisomes for viral RNA replication and that this process is accompanied by dramatic changes in peroxisome morphology, the most remarkable of which is the extensive inward vesiculation of the peroxisomal boundary membrane leading to the formation of a peroxisomal multivesicular body (pMVB). While it is unclear how the internal vesicles of a pMVB form, they appear to serve in effectively concentrating viral membrane-bound replication complexes and protecting nascent viral RNAs from host-cell defences. Here, we review briefly the biogenesis of peroxisomes and pMVBs and discuss recent studies that have begun to shed light on how components of the tombusvirus replicase exploit the molecular mechanisms involved in peroxisome membrane protein sorting. We also address the question of what controls invagination and vesicle formation at the peroxisomal membrane during pMVB biogenesis. We propose that tombusviruses exploit protein constituents of the class E vacuolar protein-sorting pathway referred to as ESCRT (endosomal sorting complex required for transport) in the formation of pMVBs. This new pMVB–ESCRT hypothesis reconciles current paradigms of pMVB biogenesis with the role of ESCRT in endosomal multivesicular body formation and the ability of enveloped RNA viruses, including HIV, to appropriate the ESCRT machinery to execute their budding programme from cells.
Collapse
Affiliation(s)
- Robert T. Mullen
- Department of Molecular and Cellular Biology, The University of Guelph, Guelph, ON N1G 2W1, Canada
- Harrington Department of Bioengineering, Arizona State University, Tempe, AZ 85287-9709, USA
| | - Andrew W. McCartney
- Department of Molecular and Cellular Biology, The University of Guelph, Guelph, ON N1G 2W1, Canada
- Harrington Department of Bioengineering, Arizona State University, Tempe, AZ 85287-9709, USA
| | - C. Robb Flynn
- Department of Molecular and Cellular Biology, The University of Guelph, Guelph, ON N1G 2W1, Canada
- Harrington Department of Bioengineering, Arizona State University, Tempe, AZ 85287-9709, USA
| | - Graham S.T. Smith
- Department of Molecular and Cellular Biology, The University of Guelph, Guelph, ON N1G 2W1, Canada
- Harrington Department of Bioengineering, Arizona State University, Tempe, AZ 85287-9709, USA
| |
Collapse
|
14
|
Baker A, Sparkes IA. Peroxisome protein import: some answers, more questions. CURRENT OPINION IN PLANT BIOLOGY 2005; 8:640-7. [PMID: 16182600 DOI: 10.1016/j.pbi.2005.09.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2005] [Accepted: 09/13/2005] [Indexed: 05/04/2023]
Abstract
Recent advances in the study of plant peroxisomes are shedding new light on the importance of these organelles for plant development, and are revealing similarities and differences in peroxisome protein import pathways between plants, animals and fungi. For example, the import of matrix proteins that carry the PTS1 and PTS2 targeting signals is coupled in plants as it is in mammals, whereas these import pathways are separate in fungi. The expression of a human peroxisomal ATPase partially rescues the equivalent Arabidopsis mutant. Ubiquitination might play a role in receptor recycling in Saccharomyces cerevisiae and exciting progress is being made through studies of the targeting of membrane proteins.
Collapse
Affiliation(s)
- Alison Baker
- Centre for Plant Sciences, University of Leeds, Leeds LS2 9JT, UK.
| | | |
Collapse
|
15
|
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.
Collapse
Affiliation(s)
- Lan Zhang
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0322, USA
| | | | | |
Collapse
|
16
|
Bonsegna S, Slocombe SP, De Bellis L, Baker A. AtLACS7 interacts with the TPR domains of the PTS1 receptor PEX5. Arch Biochem Biophys 2005; 443:74-81. [PMID: 16256065 DOI: 10.1016/j.abb.2005.09.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2005] [Revised: 09/16/2005] [Accepted: 09/17/2005] [Indexed: 11/24/2022]
Abstract
Long-chain acyl-CoA synthetases (LACSs) activate fatty acids for further metabolism and are encoded by a multi-gene family in Arabidopsis. AtLACS6 possesses a type 2 (PTS2) peroxisomal targeting sequence, whilst AtLACS7 has both a type 1 and type 2 peroxisomal targeting sequence. AtLACS7 was used as bait in a yeast two-hybrid screen. Multiple clones of the PTS1 receptor PEX5 were isolated. Quantitative beta-galactosidase assay indicated that full-length PEX5 interacts with AtLACS7 with higher affinity than the TPR domains alone. The interaction between PEX5 and AtLACS7 was confirmed by co-immunoprecipitation and shown to be specific for the PTS1, therefore the AtLACS7 PTS1 is accessible to bind PEX5 in the full-length AtLACS7 protein. The expression profile of AtLACS6, AtLACS7, AtPEX5, and AtPEX7 revealed that AtLACS6 and 7 have distinct patterns of expression and we speculate that the possession of two targeting signals may be advantageous for the import of AtLACS7 when receptors may be limiting.
Collapse
Affiliation(s)
- Stefania Bonsegna
- Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, Università degli Studi di Lecce, Italy
| | | | | | | |
Collapse
|
17
|
Karnik SK, Trelease RN. Arabidopsis peroxin 16 coexists at steady state in peroxisomes and endoplasmic reticulum. PLANT PHYSIOLOGY 2005; 138:1967-81. [PMID: 16040658 PMCID: PMC1183388 DOI: 10.1104/pp.105.061291] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Homologs of peroxin 16 genes (PEX16) have been identified only in Yarrowia lipolytica, humans (Homo sapiens), and Arabidopsis (Arabidopsis thaliana). The Arabidopsis gene (AtPEX16), previously reported as the SSE1 gene, codes for a predicted 42-kD membrane peroxin protein (AtPex16p). Lin et al. (Y. Lin, J.E. Cluette-Brown, H.M. Goodman [2004] Plant Physiol 135: 814-827) reported that SSE1/AtPEX16 was essential for endoplasmic reticulum (ER)-dependent oil and protein body biogenesis in peroxisome-deficient maturing seeds and likely also was involved in peroxisomal biogenesis based on localization of stably expressed green fluorescent protein::AtPex16p in peroxisomes of Arabidopsis plants. In this study with Arabidopsis suspension-cultured cells, combined in vivo and in vitro experiments revealed a novel dual organelle localization and corresponding membrane association/topology of endogenous AtPex16p. Immunofluorescence microscopy with antigen affinity-purified IgGs showed an unambiguous, steady-state coexistence of AtPex16p in suspension cell peroxisomes and ER. AtPex16p also was observed in peroxisomes and ER of root and leaf cells. Cell fractionation experiments surprisingly revealed two immunorelated polypeptides, 42 kD (expected) and 52 kD (unexpected), in homogenates and microsome membrane pellets derived from roots, inflorescence, and suspension cells. Suc-gradient purifications confirmed the presence of both 42-kD and 52-kD polypeptides in isolated peroxisomes (isopycnic separation) and in rough ER vesicles (Mg2+ shifted). They were found peripherally associated with peroxisome and ER membranes but not as covalently bound subunits of AtPex16p. Both were mostly on the matrix side of peroxisomal membranes and unexpectedly mostly on the cytosolic side of ER membranes. In summary, AtPex16p is the only authentic plant peroxin homolog known to coexist at steady state within peroxisomes and ER; these data provide new insights in support of its ER-related, multifunctional roles in organelle biogenesis.
Collapse
Affiliation(s)
- Sheetal K Karnik
- Arizona State University School of Life Sciences, Tempe, Arizona 85287-4501, USA
| | | |
Collapse
|
18
|
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.
Collapse
Affiliation(s)
- Ines Heiland
- Ruhr-Universität Bochum, Institut für Physiologische Chemie, Bochum, Germany
| | | |
Collapse
|
19
|
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.
Collapse
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
| | | | | | | | | |
Collapse
|
20
|
Rottensteiner H, Kramer A, Lorenzen S, Stein K, Landgraf C, Volkmer-Engert R, Erdmann R. Peroxisomal membrane proteins contain common Pex19p-binding sites that are an integral part of their targeting signals. Mol Biol Cell 2004; 15:3406-17. [PMID: 15133130 PMCID: PMC452593 DOI: 10.1091/mbc.e04-03-0188] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Targeting of peroxisomal membrane proteins (PMPs) is a multistep process that requires not only recognition of PMPs in the cytosol but also their insertion into the peroxisomal membrane. As a consequence, targeting signals of PMPs (mPTS) are rather complex. A candidate protein for the PMP recognition event is Pex19p, which interacts with most PMPs. However, the respective Pex19p-binding sites are ill-defined and it is currently disputed whether these sites are contained within mPTS. By using synthetic peptide scans and yeast two-hybrid analyses, we determined and characterized Pex19p-binding sites in Pex11p and Pex13p, two PMPs from Saccharomyces cerevisiae. The sites turned out to be composed of a short helical motif with a minimal length of 11 amino acids. With the acquired data, it proved possible to predict and experimentally verify Pex19p-binding sites in several other PMPs by applying a pattern search and a prediction matrix. A peroxisomally targeted Pex13p fragment became mislocalized to the endoplasmic reticulum in the absence of its Pex19p-binding site. By adding the heterologous binding site of Pex11p, peroxisomal targeting of the Pex13p fragment was restored. We conclude that Pex19p-binding sites are well-defined entities that represent an essential part of the mPTS.
Collapse
|