1
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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.
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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.
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2
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Ali BA, Judy RM, Chowdhury S, Jacobsen NK, Castanzo DT, Carr KL, Richardson CD, Lander GC, Martin A, Gardner BM. The N1 domain of the peroxisomal AAA-ATPase Pex6 is required for Pex15 binding and proper assembly with Pex1. J Biol Chem 2024; 300:105504. [PMID: 38036174 PMCID: PMC10777020 DOI: 10.1016/j.jbc.2023.105504] [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: 09/08/2023] [Revised: 11/07/2023] [Accepted: 11/17/2023] [Indexed: 12/02/2023] Open
Abstract
The heterohexameric ATPases associated with diverse cellular activities (AAA)-ATPase Pex1/Pex6 is essential for the formation and maintenance of peroxisomes. Pex1/Pex6, similar to other AAA-ATPases, uses the energy from ATP hydrolysis to mechanically thread substrate proteins through its central pore, thereby unfolding them. In related AAA-ATPase motors, substrates are recruited through binding to the motor's N-terminal domains or N terminally bound cofactors. Here, we use structural and biochemical techniques to characterize the function of the N1 domain in Pex6 from budding yeast, Saccharomyces cerevisiae. We found that although Pex1/ΔN1-Pex6 is an active ATPase in vitro, it does not support Pex1/Pex6 function at the peroxisome in vivo. An X-ray crystal structure of the isolated Pex6 N1 domain shows that the Pex6 N1 domain shares the same fold as the N-terminal domains of PEX1, CDC48, and NSF, despite poor sequence conservation. Integrating this structure with a cryo-EM reconstruction of Pex1/Pex6, AlphaFold2 predictions, and biochemical assays shows that Pex6 N1 mediates binding to both the peroxisomal membrane tether Pex15 and an extended loop from the D2 ATPase domain of Pex1 that influences Pex1/Pex6 heterohexamer stability. Given the direct interactions with both Pex15 and the D2 ATPase domains, the Pex6 N1 domain is poised to coordinate binding of cofactors and substrates with Pex1/Pex6 ATPase activity.
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Affiliation(s)
- Bashir A Ali
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California, USA
| | - Ryan M Judy
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California, USA
| | - Saikat Chowdhury
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, USA; Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, USA; CSIR-Centre for Cellular and Molecular Biology, Hyderabad, Telangana, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh, India
| | - Nicole K Jacobsen
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California, USA
| | - Dominic T Castanzo
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California, USA
| | - Kaili L Carr
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California, USA
| | - Chris D Richardson
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California, USA
| | - Gabriel C Lander
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, USA
| | - Andreas Martin
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California, USA; California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, California, USA; Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, California, USA
| | - Brooke M Gardner
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California, USA.
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3
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Yu M, Zhang M, Chen Q, Huang T, Gan R, Yan X. A novel compound heterozygous PEX1 variant in Heimler syndrome. Exp Eye Res 2023; 237:109688. [PMID: 37871882 DOI: 10.1016/j.exer.2023.109688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 10/14/2023] [Accepted: 10/20/2023] [Indexed: 10/25/2023]
Abstract
Heimler syndrome (HS) is a rare autosomal recessive hereditary disease that is caused by biallelic variants in peroxisomal biogenic factor 1 gene (PEX1), peroxisomal biogenic factor 6 gene (PEX6) or peroxisomal biogenic factor 26 gene (PEX26), resulting in intracellular peroxisomal dysfunction (PBDs). We report a patient with HS with a new compound heterozygous PEX1 variant. Exon sequencing was used to screen pathologic variants in the patient. Retinal characteristics and serum metabolome alterations were evaluated. Scanning laser ophthalmoscope showed a large area of retinal choroidal atrophy at the posterior pole of the retina, with scattered patchy subretinal pigmentation. Optical coherence tomography showed fovea atrophy accompanied by retinal retinoschisis in the right eye and macular retinoschisis and edema in the left eye. The electroretinogram showed obviously reduced amplitudes of a-waves and b-waves under photopic and scotopic conditions in both eyes. Visual field tests showed a reduced central visual field in both eyes. Exon sequencing identified the compound heterozygous variant including c.2966T > C and c.1670+1G > T of the PEX1 gene, with the latter being novel. Nontargeted determination of total lipid metabolites and targeted determination of medium- and long-chain fatty acids in the serum of the patient and his healthy sibling were tested. This study identified a new compound heterozygous PEX1 variant, expanding our understanding of phenotypes in HS.
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Affiliation(s)
- Mingyu Yu
- Shenzhen Eye Hospital, Jinan University, Shenzhen Eye Institute, Shenzhen, China
| | - Min Zhang
- School of Medicine, Anhui University of Science and Technology, Huainan, China
| | - Qingshan Chen
- Shenzhen Eye Hospital, Jinan University, Shenzhen Eye Institute, Shenzhen, China
| | - Tao Huang
- Shenzhen Eye Hospital, Jinan University, Shenzhen Eye Institute, Shenzhen, China
| | - Run Gan
- Shenzhen Eye Hospital, Jinan University, Shenzhen Eye Institute, Shenzhen, China
| | - Xiaohe Yan
- Shenzhen Eye Hospital, Jinan University, Shenzhen Eye Institute, Shenzhen, China.
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4
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Rüttermann M, Koci M, Lill P, Geladas ED, Kaschani F, Klink BU, Erdmann R, Gatsogiannis C. Structure of the peroxisomal Pex1/Pex6 ATPase complex bound to a substrate. Nat Commun 2023; 14:5942. [PMID: 37741838 PMCID: PMC10518020 DOI: 10.1038/s41467-023-41640-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 09/12/2023] [Indexed: 09/25/2023] Open
Abstract
The double-ring AAA+ ATPase Pex1/Pex6 is required for peroxisomal receptor recycling and is essential for peroxisome formation. Pex1/Pex6 mutations cause severe peroxisome associated developmental disorders. Despite its pathophysiological importance, mechanistic details of the heterohexamer are not yet available. Here, we report cryoEM structures of Pex1/Pex6 from Saccharomyces cerevisiae, with an endogenous protein substrate trapped in the central pore of the catalytically active second ring (D2). Pairs of Pex1/Pex6(D2) subdomains engage the substrate via a staircase of pore-1 loops with distinct properties. The first ring (D1) is catalytically inactive but undergoes significant conformational changes resulting in alternate widening and narrowing of its pore. These events are fueled by ATP hydrolysis in the D2 ring and disengagement of a "twin-seam" Pex1/Pex6(D2) heterodimer from the staircase. Mechanical forces are propagated in a unique manner along Pex1/Pex6 interfaces that are not available in homo-oligomeric AAA-ATPases. Our structural analysis reveals the mechanisms of how Pex1 and Pex6 coordinate to achieve substrate translocation.
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Affiliation(s)
- Maximilian Rüttermann
- Institute for Medical Physics and Biophysics, University Münster, Münster, Germany
- Center for Soft Nanoscience (SoN), University Münster, Münster, Germany
| | - Michelle Koci
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Pascal Lill
- Institute for Medical Physics and Biophysics, University Münster, Münster, Germany
- Center for Soft Nanoscience (SoN), University Münster, Münster, Germany
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Ermis Dionysios Geladas
- Institute for Medical Physics and Biophysics, University Münster, Münster, Germany
- Center for Soft Nanoscience (SoN), University Münster, Münster, Germany
| | - Farnusch Kaschani
- Analytics Core Facility Essen, Center of Medical Biotechnology (ZMB), Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - Björn Udo Klink
- Institute for Medical Physics and Biophysics, University Münster, Münster, Germany
- Center for Soft Nanoscience (SoN), University Münster, Münster, Germany
| | - Ralf Erdmann
- Institute for Biochemistry and Pathobiochemistry, Department of Systems Biochemistry, Ruhr-University Bochum, Bochum, Germany
| | - Christos Gatsogiannis
- Institute for Medical Physics and Biophysics, University Münster, Münster, Germany.
- Center for Soft Nanoscience (SoN), University Münster, Münster, Germany.
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.
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5
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Ali BA, Judy RM, Chowdhury S, Jacobsen NK, Castanzo DT, Carr KL, Richardson CD, Lander GC, Martin A, Gardner BM. The Pex6 N1 domain is required for Pex15 binding and proper assembly with Pex1. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.15.557798. [PMID: 37745580 PMCID: PMC10516024 DOI: 10.1101/2023.09.15.557798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
The heterohexameric AAA-ATPase Pex1/Pex6 is essential for the formation and maintenance of peroxisomes. Pex1/Pex6, similar to other AAA-ATPases, uses the energy from ATP hydrolysis to mechanically thread substrate proteins through its central pore, thereby unfolding them. In related AAA-ATPase motors, substrates are recruited through binding to the motor's N-terminal domains or N-terminally bound co-factors. Here we use structural and biochemical techniques to characterize the function of the N1 domain in Pex6 from budding yeast, S. cerevisiae. We found that although Pex1/ΔN1-Pex6 is an active ATPase in vitro, it does not support Pex1/Pex6 function at the peroxisome in vivo. An X-ray crystal structure of the isolated Pex6 N1 domain shows that the Pex6 N1 domain shares the same fold as the N terminal domains of PEX1, CDC48, or NSF, despite poor sequence conservation. Integrating this structure with a cryo-EM reconstruction of Pex1/Pex6, AlphaFold2 predictions, and biochemical assays shows that Pex6 N1 mediates binding to both the peroxisomal membrane tether Pex15 and an extended loop from the D2 ATPase domain of Pex1 that influences Pex1/Pex6 heterohexamer stability. Given the direct interactions with both Pex15 and the D2 ATPase domains, the Pex6 N1 domain is poised to coordinate binding of co-factors and substrates with Pex1/Pex6 ATPase activity.
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Affiliation(s)
- Bashir A Ali
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA, USA
| | - Ryan M Judy
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA, USA
| | - Saikat Chowdhury
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
- Department of Biochemistry and Cell Biology, Stony Brook University, 100 Nicolls Road, Stony Brook, NY 11794, USA
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, Telangana 500007, India. Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh 201002, India
| | - Nicole K Jacobsen
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA, USA
| | - Dominic T Castanzo
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Kaili L Carr
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Chris D Richardson
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA, USA
| | - Gabriel C Lander
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Andreas Martin
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, CA 94720, USA
- Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Brooke M Gardner
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA, USA
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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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7
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Ott J, Sehr J, Schmidt N, Schliebs W, Erdmann R. Comparison of human PEX knockout cell lines suggests a dual role of PEX1 in peroxisome biogenesis. Biol Chem 2023; 404:209-219. [PMID: 36534601 DOI: 10.1515/hsz-2022-0223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 12/05/2022] [Indexed: 12/24/2022]
Abstract
For the biogenesis and maintenance of peroxisomes several proteins, called peroxins, are essential. Malfunctions of these proteins lead to severe diseases summarized as peroxisome biogenesis disorders. The different genetic background of patient-derived cell lines and the residual expression of mutated PEX genes impede analysis of the whole spectrum of cellular functions of affected peroxins. To overcome these difficulties, we have generated a selected PEX knockout resource of HEK T-REx293 cells using the CRISPR/Cas9 technique. Comparative analyses of whole cell lysates revealed PEX-KO specific alterations in the steady-state level of peroxins and variations in the import efficacy of matrix proteins with a Type 2 peroxisomal targeting signal. One of the observed differences concerned PEX1 as in the complete absence of the protein, the number of peroxisomal ghosts is significantly increased. Upon expression of PEX1, import competence and abundance of peroxisomes was adjusted to the level of normal HEK cells. In contrast, expression of an alternatively spliced PEX1 isoform lacking 321 amino acids of the N-terminal region failed to rescue the peroxisomal import defects but reduced the number of peroxisomal vesicles. All in all, the data suggest a novel 'moonlighting' function of human PEX1 in the regulation of pre-peroxisomal vesicles.
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Affiliation(s)
- Julia Ott
- Department of Systems Biochemistry, Institute for Biochemistry and Pathobiochemistry, Ruhr University Bochum, D-44780 Bochum, Germany
| | - Jessica Sehr
- Department of Systems Biochemistry, Institute for Biochemistry and Pathobiochemistry, Ruhr University Bochum, D-44780 Bochum, Germany
| | - Nadine Schmidt
- Department of Systems Biochemistry, Institute for Biochemistry and Pathobiochemistry, Ruhr University Bochum, D-44780 Bochum, Germany
| | - Wolfgang Schliebs
- Department of Systems Biochemistry, Institute for Biochemistry and Pathobiochemistry, Ruhr University Bochum, D-44780 Bochum, Germany
| | - Ralf Erdmann
- Department of Systems Biochemistry, Institute for Biochemistry and Pathobiochemistry, Ruhr University Bochum, D-44780 Bochum, Germany
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8
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Rüttermann M, Gatsogiannis C. Good things come to those who bait: the peroxisomal docking complex. Biol Chem 2023; 404:107-119. [PMID: 36117327 DOI: 10.1515/hsz-2022-0161] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 08/25/2022] [Indexed: 11/15/2022]
Abstract
Peroxisomal integrity and function are highly dependent on its membrane and soluble (matrix) components. Matrix enzymes are imported post-translationally in a folded or even oligomeric state, via a still mysterious protein translocation mechanism. They are guided to peroxisomes via the Peroxisomal Targeting Signal (PTS) sequences which are recognized by specific cytosolic receptors, Pex5, Pex7 and Pex9. Subsequently, cargo-loaded receptors bind to the docking complex in an initial step, followed by channel formation, cargo-release, receptor-recycling and -quality control. The docking complexes of different species share Pex14 as their core component but differ in composition and oligomeric state of Pex14. Here we review and highlight the latest insights on the structure and function of the peroxisomal docking complex. We summarize differences between yeast and mammals and then we integrate this knowledge into our current understanding of the import machinery.
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Affiliation(s)
- Maximilian Rüttermann
- Institute for Medical Physics and Biophysics and Center for Soft Nanoscience, Westfälische Wilhelms Universität Münster, D-48149 Münster, Germany
| | - Christos Gatsogiannis
- Institute for Medical Physics and Biophysics and Center for Soft Nanoscience, Westfälische Wilhelms Universität Münster, D-48149 Münster, Germany
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9
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Ghosh M, Denkert N, Reuter M, Klümper J, Reglinski K, Peschel R, Schliebs W, Erdmann R, Meinecke M. Dynamics of the translocation pore of the human peroxisomal protein import machinery. Biol Chem 2023; 404:169-178. [PMID: 35977096 DOI: 10.1515/hsz-2022-0170] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 07/05/2022] [Indexed: 01/15/2023]
Abstract
Peroxisomal matrix proteins are synthesized on cytosolic ribosomes and imported in a posttranslational manner. Intricate protein import machineries have evolved that catalyze the different stages of translocation. In humans, PEX5L was found to be an essential component of the peroxisomal translocon. PEX5L is the main receptor for substrate proteins carrying a peroxisomal targeting signal (PTS). Substrates are bound by soluble PEX5L in the cytosol after which the cargo-receptor complex is recruited to peroxisomal membranes. Here, PEX5L interacts with the docking protein PEX14 and becomes part of an integral membrane protein complex that facilitates substrate translocation into the peroxisomal lumen in a still unknown process. In this study, we show that PEX5L containing complexes purified from human peroxisomal membranes constitute water-filled pores when reconstituted into planar-lipid membranes. Channel characteristics were highly dynamic in terms of conductance states, selectivity and voltage- and substrate-sensitivity. Our results show that a PEX5L associated pore exists in human peroxisomes, which can be activated by receptor-cargo complexes.
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Affiliation(s)
- Mausumi Ghosh
- Biochemistry Center (BZH), Heidelberg University, D-69120 Heidelberg, Germany.,Institute for Cellular Biochemistry, University Medical Center Göttingen, D-37073 Göttingen, Germany
| | - Niels Denkert
- Biochemistry Center (BZH), Heidelberg University, D-69120 Heidelberg, Germany.,Institute for Cellular Biochemistry, University Medical Center Göttingen, D-37073 Göttingen, Germany
| | - Maren Reuter
- Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, D-44780 Bochum, Germany
| | - Jessica Klümper
- Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, D-44780 Bochum, Germany
| | - Katharina Reglinski
- Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, D-44780 Bochum, Germany
| | - Rebecca Peschel
- Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, D-44780 Bochum, Germany
| | - Wolfgang Schliebs
- Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, D-44780 Bochum, Germany
| | - Ralf Erdmann
- Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, D-44780 Bochum, Germany
| | - Michael Meinecke
- Biochemistry Center (BZH), Heidelberg University, D-69120 Heidelberg, Germany.,Institute for Cellular Biochemistry, University Medical Center Göttingen, D-37073 Göttingen, Germany
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Pedrosa AG, Francisco T, Rodrigues TA, Ferreira MJ, van der Heden van Noort GJ, Azevedo JE. The Extraction Mechanism of Monoubiquitinated PEX5 from the Peroxisomal Membrane. J Mol Biol 2023; 435:167896. [PMID: 36442669 DOI: 10.1016/j.jmb.2022.167896] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 11/19/2022] [Accepted: 11/21/2022] [Indexed: 11/27/2022]
Abstract
The AAA ATPases PEX1•PEX6 extract PEX5, the peroxisomal protein shuttling receptor, from the peroxisomal membrane so that a new protein transport cycle can start. Extraction requires ubiquitination of PEX5 at residue 11 and involves a threading mechanism, but how exactly this occurs is unclear. We used a cell-free in vitro system and a variety of engineered PEX5 and ubiquitin molecules to challenge the extraction machinery. We show that PEX5 modified with a single ubiquitin is a substrate for extraction and extend previous findings proposing that neither the N- nor the C-terminus of PEX5 are required for extraction. Chimeric PEX5 molecules possessing a branched polypeptide structure at their C-terminal domains can still be extracted from the peroxisomal membrane thus suggesting that the extraction machinery can thread more than one polypeptide chain simultaneously. Importantly, we found that the PEX5-linked monoubiquitin is unfolded at a pre-extraction stage and, accordingly, an intra-molecularly cross-linked ubiquitin blocked extraction when conjugated to residue 11 of PEX5. Collectively, our data suggest that the PEX5-linked monoubiquitin is the extraction initiator and that the complete ubiquitin-PEX5 conjugate is threaded by PEX1•PEX6.
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Affiliation(s)
- Ana G Pedrosa
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal
| | - Tânia Francisco
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal
| | - Tony A Rodrigues
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal
| | - Maria J Ferreira
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal
| | - Gerbrand J van der Heden van Noort
- Oncode Institute and Department of Cell and Chemical Biology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC, Leiden, The Netherlands
| | - Jorge E Azevedo
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal.
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11
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Pandey S, Dodt G. Purification of a Recombinant Human PEX1/PEX6 AAA+ ATPase Complex from HEK293TT Cells. Methods Mol Biol 2023; 2643:359-372. [PMID: 36952198 DOI: 10.1007/978-1-0716-3048-8_25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/24/2023]
Abstract
The heteromeric complex of the two AAA+ ATPases PEX1 and PEX6 is involved in the export of the monoubiquitinated import receptor PEX5 from the peroxisomal membrane. Mutations in this complex make up for over 60% of the patients with Peroxisomal Biogenesis Disorders. To have better options for the treatment of the milder mutations we purified the human PEX1/PEX6 complex after overexpression of plasmids encoding tagged proteins from HEK293TT cells. We used a combination of a HisTrap Column (Ni-NTA chromatography) and a Strep-Tactin®XT cartridge for small-scale purification of the complex using the His-tag of PEX1 and the Strep-tagII of PEX6.
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Affiliation(s)
- Saroj Pandey
- Interfaculty Institute of Biochemistry (IFIB), Cell Biochemistry, University of Tuebingen, Tuebingen, Germany
| | - Gabriele Dodt
- Interfaculty Institute of Biochemistry (IFIB), Cell Biochemistry, University of Tuebingen, Tuebingen, Germany.
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12
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Feng P, Skowyra ML, Rapoport TA. Structure and function of the peroxisomal ubiquitin ligase complex. Biochem Soc Trans 2022; 50:1921-1930. [PMID: 36421406 PMCID: PMC9788354 DOI: 10.1042/bst20221393] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/10/2022] [Accepted: 11/14/2022] [Indexed: 09/26/2023]
Abstract
Peroxisomes are membrane-bounded organelles that exist in most eukaryotic cells and are involved in the oxidation of fatty acids and the destruction of reactive oxygen species. Depending on the organism, they house additional metabolic reactions that range from glycolysis in parasitic protozoa to the production of ether lipids in animals and antibiotics in fungi. The importance of peroxisomes for human health is revealed by various disorders - notably the Zellweger spectrum - that are caused by defects in peroxisome biogenesis and are often fatal. Most peroxisomal metabolic enzymes reside in the lumen, but are synthesized in the cytosol and imported into the organelle by mobile receptors. The receptors accompany cargo all the way into the lumen and must return to the cytosol to start a new import cycle. Recycling requires receptor monoubiquitination by a membrane-embedded ubiquitin ligase complex composed of three RING finger (RF) domain-containing proteins: PEX2, PEX10, and PEX12. A recent cryo-electron microscopy (cryo-EM) structure of the complex reveals its function as a retro-translocation channel for peroxisomal import receptors. Each subunit of the complex contributes five transmembrane segments that assemble into an open channel. The N terminus of a receptor likely inserts into the pore from the lumenal side, and is then monoubiquitinated by one of the RFs to enable extraction into the cytosol. If recycling is compromised, receptors are polyubiquitinated by the concerted action of the other two RFs and ultimately degraded. The new data provide mechanistic insight into a crucial step of peroxisomal protein import.
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Affiliation(s)
- Peiqiang Feng
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, U.S.A
| | - Michael L. Skowyra
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, U.S.A
| | - Tom A. Rapoport
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, U.S.A
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13
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Chang KJ, Wu HY, Yarmishyn AA, Li CY, Hsiao YJ, Chi YC, Lo TC, Dai HJ, Yang YC, Liu DH, Hwang DK, Chen SJ, Hsu CC, Kao CL. Genetics behind Cerebral Disease with Ocular Comorbidity: Finding Parallels between the Brain and Eye Molecular Pathology. Int J Mol Sci 2022; 23:ijms23179707. [PMID: 36077104 PMCID: PMC9456058 DOI: 10.3390/ijms23179707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 08/18/2022] [Accepted: 08/22/2022] [Indexed: 11/30/2022] Open
Abstract
Cerebral visual impairments (CVIs) is an umbrella term that categorizes miscellaneous visual defects with parallel genetic brain disorders. While the manifestations of CVIs are diverse and ambiguous, molecular diagnostics stand out as a powerful approach for understanding pathomechanisms in CVIs. Nevertheless, the characterization of CVI disease cohorts has been fragmented and lacks integration. By revisiting the genome-wide and phenome-wide association studies (GWAS and PheWAS), we clustered a handful of renowned CVIs into five ontology groups, namely ciliopathies (Joubert syndrome, Bardet–Biedl syndrome, Alstrom syndrome), demyelination diseases (multiple sclerosis, Alexander disease, Pelizaeus–Merzbacher disease), transcriptional deregulation diseases (Mowat–Wilson disease, Pitt–Hopkins disease, Rett syndrome, Cockayne syndrome, X-linked alpha-thalassaemia mental retardation), compromised peroxisome disorders (Zellweger spectrum disorder, Refsum disease), and channelopathies (neuromyelitis optica spectrum disorder), and reviewed several mutation hotspots currently found to be associated with the CVIs. Moreover, we discussed the common manifestations in the brain and the eye, and collated animal study findings to discuss plausible gene editing strategies for future CVI correction.
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Affiliation(s)
- Kao-Jung Chang
- School of Medicine, National Yang Ming Chiao Tung University, Taipei 112304, Taiwan
- Department of Medical Research, Taipei Veterans General Hospital, Taipei 11217, Taiwan
- Institute of Clinical Medicine, National Yang Ming Chiao Tung University, Taipei 112304, Taiwan
| | - Hsin-Yu Wu
- School of Medicine, National Yang Ming Chiao Tung University, Taipei 112304, Taiwan
- Department of Medical Research, Taipei Veterans General Hospital, Taipei 11217, Taiwan
| | | | - Cheng-Yi Li
- School of Medicine, National Yang Ming Chiao Tung University, Taipei 112304, Taiwan
- Department of Medical Research, Taipei Veterans General Hospital, Taipei 11217, Taiwan
| | - Yu-Jer Hsiao
- School of Medicine, National Yang Ming Chiao Tung University, Taipei 112304, Taiwan
- Department of Medical Research, Taipei Veterans General Hospital, Taipei 11217, Taiwan
| | - Yi-Chun Chi
- Department of Ophthalmology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
| | - Tzu-Chen Lo
- School of Medicine, National Yang Ming Chiao Tung University, Taipei 112304, Taiwan
- Department of Ophthalmology, Taipei Veterans General Hospital, Taipei 11217, Taiwan
| | - He-Jhen Dai
- School of Medicine, National Yang Ming Chiao Tung University, Taipei 112304, Taiwan
- Department of Medical Research, Taipei Veterans General Hospital, Taipei 11217, Taiwan
| | - Yi-Chiang Yang
- Department of Physical Medicine and Rehabilitation, Taipei Veterans General Hospital, Taipei 11217, Taiwan
| | - Ding-Hao Liu
- Institute of Clinical Medicine, National Yang Ming Chiao Tung University, Taipei 112304, Taiwan
- Department of Physical Medicine and Rehabilitation, Taipei Veterans General Hospital, Taipei 11217, Taiwan
| | - De-Kuang Hwang
- School of Medicine, National Yang Ming Chiao Tung University, Taipei 112304, Taiwan
- Institute of Clinical Medicine, National Yang Ming Chiao Tung University, Taipei 112304, Taiwan
- Department of Ophthalmology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
| | - Shih-Jen Chen
- Department of Ophthalmology, Taipei Veterans General Hospital, Taipei 11217, Taiwan
| | - Chih-Chien Hsu
- School of Medicine, National Yang Ming Chiao Tung University, Taipei 112304, Taiwan
- Institute of Clinical Medicine, National Yang Ming Chiao Tung University, Taipei 112304, Taiwan
- Department of Ophthalmology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
- Correspondence: (C.-C.H.); (C.-L.K.); Tel.: +886-2-287-573-25 (C.-C.H.); +886-2-287-573-63 (C.-L.K.)
| | - Chung-Lan Kao
- Institute of Clinical Medicine, National Yang Ming Chiao Tung University, Taipei 112304, Taiwan
- Department of Physical Medicine and Rehabilitation, Taipei Veterans General Hospital, Taipei 11217, Taiwan
- Department of Physical Medicine and Rehabilitation, School of Medicine, National Yang Ming Chiao Tung University, Taipei 112304, Taiwan
- Center for Intelligent Drug Systems and Smart Bio-Devices (IDS2B), National Yang Ming Chiao Tung University, Hsinchu 300093, Taiwan
- Correspondence: (C.-C.H.); (C.-L.K.); Tel.: +886-2-287-573-25 (C.-C.H.); +886-2-287-573-63 (C.-L.K.)
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14
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Insights into the Structure and Function of the Pex1/Pex6 AAA-ATPase in Peroxisome Homeostasis. Cells 2022; 11:cells11132067. [PMID: 35805150 PMCID: PMC9265785 DOI: 10.3390/cells11132067] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 06/25/2022] [Accepted: 06/26/2022] [Indexed: 02/01/2023] Open
Abstract
The AAA-ATPases Pex1 and Pex6 are required for the formation and maintenance of peroxisomes, membrane-bound organelles that harbor enzymes for specialized metabolism. Together, Pex1 and Pex6 form a heterohexameric AAA-ATPase capable of unfolding substrate proteins via processive threading through a central pore. Here, we review the proposed roles for Pex1/Pex6 in peroxisome biogenesis and degradation, discussing how the unfolding of potential substrates contributes to peroxisome homeostasis. We also consider how advances in cryo-EM, computational structure prediction, and mechanisms of related ATPases are improving our understanding of how Pex1/Pex6 converts ATP hydrolysis into mechanical force. Since mutations in PEX1 and PEX6 cause the majority of known cases of peroxisome biogenesis disorders such as Zellweger syndrome, insights into Pex1/Pex6 structure and function are important for understanding peroxisomes in human health and disease.
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15
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Falter C, Reumann S. The essential role of fungal peroxisomes in plant infection. MOLECULAR PLANT PATHOLOGY 2022; 23:781-794. [PMID: 35001508 PMCID: PMC9104257 DOI: 10.1111/mpp.13180] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 12/06/2021] [Accepted: 12/06/2021] [Indexed: 06/09/2023]
Abstract
Several filamentous fungi are ecologically and economically important plant pathogens that infect a broad variety of crops. They cause high annual yield losses and contaminate seeds and fruits with mycotoxins. Not only powerful infection structures and detrimental toxins, but also cell organelles, such as peroxisomes, play important roles in plant infection. In this review, we summarize recent research results that revealed novel peroxisomal functions of filamentous fungi and highlight the importance of peroxisomes for infection of host plants. Central for fungal virulence are two primary metabolic pathways, fatty acid β-oxidation and the glyoxylate cycle, both of which are required to produce energy, acetyl-CoA, and carbohydrates. These are ultimately needed for the synthesis of cell wall polymers and for turgor generation in infection structures. Most novel results stem from different routes of secondary metabolism and demonstrate that peroxisomes produce important precursors and house various enzymes needed for toxin production and melanization of appressoria. All these peroxisomal functions in fungal virulence might represent elegant targets for improved crop protection.
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Affiliation(s)
- Christian Falter
- Plant Biochemistry and Infection BiologyInstitute of Plant Science and MicrobiologyUniversität HamburgHamburgGermany
| | - Sigrun Reumann
- Plant Biochemistry and Infection BiologyInstitute of Plant Science and MicrobiologyUniversität HamburgHamburgGermany
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16
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Steenwyk JL, Phillips MA, Yang F, Date SS, Graham TR, Berman J, Hittinger CT, Rokas A. An orthologous gene coevolution network provides insight into eukaryotic cellular and genomic structure and function. SCIENCE ADVANCES 2022; 8:eabn0105. [PMID: 35507651 PMCID: PMC9067921 DOI: 10.1126/sciadv.abn0105] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 03/16/2022] [Indexed: 06/14/2023]
Abstract
The evolutionary rates of functionally related genes often covary. We present a gene coevolution network inferred from examining nearly 3 million orthologous gene pairs from 332 budding yeast species spanning ~400 million years of evolution. Network modules provide insight into cellular and genomic structure and function. Examination of the phenotypic impact of network perturbation using deletion mutant data from the baker's yeast Saccharomyces cerevisiae, which were obtained from previously published studies, suggests that fitness in diverse environments is affected by orthologous gene neighborhood and connectivity. Mapping the network onto the chromosomes of S. cerevisiae and Candida albicans revealed that coevolving orthologous genes are not physically clustered in either species; rather, they are often located on different chromosomes or far apart on the same chromosome. The coevolution network captures the hierarchy of cellular structure and function, provides a roadmap for genotype-to-phenotype discovery, and portrays the genome as a linked ensemble of genes.
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Affiliation(s)
- Jacob L. Steenwyk
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Megan A. Phillips
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Feng Yang
- Shmunis School of Biomedical and Cancer Research, Tel Aviv University, Ramat Aviv, Israel
- Department of Pharmacology, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China
| | - Swapneeta S. Date
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Todd R. Graham
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Judith Berman
- Shmunis School of Biomedical and Cancer Research, Tel Aviv University, Ramat Aviv, Israel
| | - Chris Todd Hittinger
- Laboratory of Genetics, DOE Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, Center for Genomic Science Innovation, J.F. Crow Institute for the Study of Evolution, University of Wisconsin-Madison, Madison, WI, USA
| | - Antonis Rokas
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
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17
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Goto-Yamada S, Oikawa K, Yamato KT, Kanai M, Hikino K, Nishimura M, Mano S. Image-Based Analysis Revealing the Molecular Mechanism of Peroxisome Dynamics in Plants. Front Cell Dev Biol 2022; 10:883491. [PMID: 35592252 PMCID: PMC9110829 DOI: 10.3389/fcell.2022.883491] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 04/15/2022] [Indexed: 11/13/2022] Open
Abstract
Peroxisomes are present in eukaryotic cells and have essential roles in various biological processes. Plant peroxisomes proliferate by de novo biosynthesis or division of pre-existing peroxisomes, degrade, or replace metabolic enzymes, in response to developmental stages, environmental changes, or external stimuli. Defects of peroxisome functions and biogenesis alter a variety of biological processes and cause aberrant plant growth. Traditionally, peroxisomal function-based screening has been employed to isolate Arabidopsis thaliana mutants that are defective in peroxisomal metabolism, such as lipid degradation and photorespiration. These analyses have revealed that the number, subcellular localization, and activity of peroxisomes are closely related to their efficient function, and the molecular mechanisms underlying peroxisome dynamics including organelle biogenesis, protein transport, and organelle interactions must be understood. Various approaches have been adopted to identify factors involved in peroxisome dynamics. With the development of imaging techniques and fluorescent proteins, peroxisome research has been accelerated. Image-based analyses provide intriguing results concerning the movement, morphology, and number of peroxisomes that were hard to obtain by other approaches. This review addresses image-based analysis of peroxisome dynamics in plants, especially A. thaliana and Marchantia polymorpha.
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Affiliation(s)
- Shino Goto-Yamada
- Małopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland
| | - Kazusato Oikawa
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Katsuyuki T. Yamato
- Faculty of Biology-Oriented Science and Technology, Kindai University, Wakayama, Japan
| | - Masatake Kanai
- Department of Cell Biology, National Institute for Basic Biology, Okazaki, Japan
| | - Kazumi Hikino
- Department of Cell Biology, National Institute for Basic Biology, Okazaki, Japan
| | - Mikio Nishimura
- Department of Biology, Faculty of Science and Engineering, Konan University, Kobe, Japan
| | - Shoji Mano
- Department of Cell Biology, National Institute for Basic Biology, Okazaki, Japan
- Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Japan
- *Correspondence: Shoji Mano
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18
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Yu H, Kamber RA, Denic V. The peroxisomal exportomer directly inhibits phosphoactivation of the pexophagy receptor Atg36 to suppress pexophagy in yeast. eLife 2022; 11:74531. [PMID: 35404228 PMCID: PMC9000956 DOI: 10.7554/elife.74531] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 03/09/2022] [Indexed: 01/21/2023] Open
Abstract
Autophagy receptor (or adaptor) proteins facilitate lysosomal destruction of various organelles in response to cellular stress, including nutrient deprivation. To what extent membrane-resident autophagy receptors also respond to organelle-restricted cues to induce selective autophagy remains poorly understood. We find that latent activation of the yeast pexophagy receptor Atg36 by the casein kinase Hrr25 in rich media is repressed by the ATPase activity of Pex1/6, the catalytic subunits of the exportomer AAA+ transmembrane complex enabling protein import into peroxisomes. Quantitative proteomics of purified Pex3, an obligate Atg36 coreceptor, support a model in which the exportomer tail anchored to the peroxisome membrane represses Atg36 phosphorylation on Pex3 without assistance from additional membrane factors. Indeed, we reconstitute inhibition of Atg36 phosphorylation in vitro using soluble Pex1/6 and define an N-terminal unstructured region of Atg36 that enables regulation by binding to Pex1. Our findings uncover a mechanism by which a compartment-specific AAA+ complex mediating organelle biogenesis and protein quality control staves off induction of selective autophagy.
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Affiliation(s)
- Houqing Yu
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | - Roarke A Kamber
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | - Vladimir Denic
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
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19
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Kim J, Bai H. Peroxisomal Stress Response and Inter-Organelle Communication in Cellular Homeostasis and Aging. Antioxidants (Basel) 2022; 11:192. [PMID: 35204075 PMCID: PMC8868334 DOI: 10.3390/antiox11020192] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 01/15/2022] [Accepted: 01/16/2022] [Indexed: 12/20/2022] Open
Abstract
Peroxisomes are key regulators of cellular and metabolic homeostasis. These organelles play important roles in redox metabolism, the oxidation of very-long-chain fatty acids (VLCFAs), and the biosynthesis of ether phospholipids. Given the essential role of peroxisomes in cellular homeostasis, peroxisomal dysfunction has been linked to various pathological conditions, tissue functional decline, and aging. In the past few decades, a variety of cellular signaling and metabolic changes have been reported to be associated with defective peroxisomes, suggesting that many cellular processes and functions depend on peroxisomes. Peroxisomes communicate with other subcellular organelles, such as the nucleus, mitochondria, endoplasmic reticulum (ER), and lysosomes. These inter-organelle communications are highly linked to the key mechanisms by which cells surveil defective peroxisomes and mount adaptive responses to protect them from damages. In this review, we highlight the major cellular changes that accompany peroxisomal dysfunction and peroxisomal inter-organelle communication through membrane contact sites, metabolic signaling, and retrograde signaling. We also discuss the age-related decline of peroxisomal protein import and its role in animal aging and age-related diseases. Unlike other organelle stress response pathways, such as the unfolded protein response (UPR) in the ER and mitochondria, the cellular signaling pathways that mediate stress responses to malfunctioning peroxisomes have not been systematically studied and investigated. Here, we coin these signaling pathways as "peroxisomal stress response pathways". Understanding peroxisomal stress response pathways and how peroxisomes communicate with other organelles are important and emerging areas of peroxisome research.
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Affiliation(s)
- Jinoh Kim
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Hua Bai
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
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20
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Khan YA, White KI, Brunger AT. The AAA+ superfamily: a review of the structural and mechanistic principles of these molecular machines. Crit Rev Biochem Mol Biol 2021; 57:156-187. [PMID: 34632886 DOI: 10.1080/10409238.2021.1979460] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
ATPases associated with diverse cellular activities (AAA+ proteins) are a superfamily of proteins found throughout all domains of life. The hallmark of this family is a conserved AAA+ domain responsible for a diverse range of cellular activities. Typically, AAA+ proteins transduce chemical energy from the hydrolysis of ATP into mechanical energy through conformational change, which can drive a variety of biological processes. AAA+ proteins operate in a variety of cellular contexts with diverse functions including disassembly of SNARE proteins, protein quality control, DNA replication, ribosome assembly, and viral replication. This breadth of function illustrates both the importance of AAA+ proteins in health and disease and emphasizes the importance of understanding conserved mechanisms of chemo-mechanical energy transduction. This review is divided into three major portions. First, the core AAA+ fold is presented. Next, the seven different clades of AAA+ proteins and structural details and reclassification pertaining to proteins in each clade are described. Finally, two well-known AAA+ proteins, NSF and its close relative p97, are reviewed in detail.
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Affiliation(s)
- Yousuf A Khan
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA.,Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA.,Department of Structural Biology, Stanford University, Stanford, CA, USA.,Department of Photon Science, Stanford University, Stanford, CA, USA.,Center for Biomedical Informatics Research, Stanford University, Stanford, CA, USA
| | - K Ian White
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA.,Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA.,Department of Structural Biology, Stanford University, Stanford, CA, USA.,Department of Photon Science, Stanford University, Stanford, CA, USA.,Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Axel T Brunger
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA.,Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA.,Department of Structural Biology, Stanford University, Stanford, CA, USA.,Department of Photon Science, Stanford University, Stanford, CA, USA.,Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
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21
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Abstract
Peroxisomes are organelles in eukaryotic cells responsible for processing several types of lipids and management of reactive oxygen species. A conserved family of peroxisome biogenesis (Peroxin, Pex) genes encode proteins essential to peroxisome biogenesis or function. In yeast and mammals, PEROXIN7 (PEX7) acts as a cytosolic receptor protein that targets enzymes containing a peroxisome targeting signal 2 (PTS2) motif for peroxisome matrix import. The PTS2 motif is not present in the Drosophila melanogaster homologs of these enzymes. However, the fly genome contains a Pex7 gene (CG6486) that is very similar to yeast and human PEX7. We find that Pex7 is expressed in tissue-specific patterns analogous to differentiating neuroblasts in D. melanogaster embryos. This is correlated with a requirement for Pex7 in this cell lineage as targeted somatic Pex7 knockout in embryonic neuroblasts reduced survival. We also found that Pex7 over-expression in the same cell lineages caused lethality during the larval stage. Targeted somatic over-expression of a Pex7 transgene in neuroblasts of Pex7 homozygous null mutants resulted in a semi-lethal phenotype similar to targeted Pex7 knockout. These findings suggest that D. melanogaster has tissue-specific requirements for Pex7 during embryo development.
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Affiliation(s)
- C Pridie
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada.,Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Andrew J Simmonds
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
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22
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Abstract
Blobel and coworkers discovered in 1978 that peroxisomal proteins are synthesized on free ribosomes in the cytosol and thus provided the grounds for the conception of peroxisomes as self-containing organelles. Peroxisomes are highly adaptive and versatile organelles carrying out a wide variety of metabolic functions. A striking feature of the peroxisomal import machinery is that proteins can traverse the peroxisomal membrane in a folded and even oligomeric state via cycling receptors. We outline essential steps of peroxisomal matrix protein import, from targeting of the proteins to the peroxisomal membrane, their translocation via transient pores and export of the corresponding cycling import receptors with emphasis on the situation in yeast. Peroxisomes can contribute to the adaptation of cells to different environmental conditions. This is realized by changes in metabolic functions and thus the enzyme composition of the organelles is adopted according to the cellular needs. In recent years, it turned out that this organellar diversity is based on an elaborate regulation of gene expression and peroxisomal protein import. The latter is in the focus of this review that summarizes our knowledge on the composition and function of the peroxisomal protein import machinery with emphasis on novel alternative protein import pathways.
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Affiliation(s)
- Thomas Walter
- Systems Biochemistry, Institute of Biochemistry and Pathobiochemistry, Faculty of Medicine, Ruhr-University Bochum, Universitätsstr. 150, 44780, Bochum, Germany
| | - Ralf Erdmann
- Systems Biochemistry, Institute of Biochemistry and Pathobiochemistry, Faculty of Medicine, Ruhr-University Bochum, Universitätsstr. 150, 44780, Bochum, Germany.
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23
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Gao FJ, Hu FY, Xu P, Qi YH, Li JK, Zhang YJ, Chen F, Chang Q, Song F, Shen SM, Xu GZ, Wu JH. Expanding the clinical and genetic spectrum of Heimler syndrome. Orphanet J Rare Dis 2019; 14:290. [PMID: 31831025 PMCID: PMC6909578 DOI: 10.1186/s13023-019-1243-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 10/29/2019] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Heimler syndrome (HS) is a rare hereditary systemic disorder, partial clinically overlapping with Usher syndrome. So far, our knowledge of HS is very limited, many cases are misdiagnosed or may not even be diagnosed at all. This study aimed to analyze the clinical and genetic characteristics of HS, and to evaluate potential phenotype-genotype correlations. RESULTS Two HS cases caused by PEX1 mutations were identified, and a novel likely pathogenic mutation, PEX1 c.895_896insTATA, was found. The main ophthalmic finding of the two patients was consistent with retinitis pigmentosa accompanied by cystoid macular edema, but short axial length and hyperopia were also observed as two previously unreported ocular phenotypes. Analysis of the literature showed that of the 29 HS patients previously reported, 12 had PEX6 mutations, 10 had PEX1 mutations, two had PEX26 mutations, and the remaining patients were not genetically tested. Three novel genotype-phenotype correlations were revealed from analysis of these patients. First, most genotypes of every HS patient include at least one missense variant; second, at least one mutation in PEX1 or PEX6 gene affects the AAA-ATPase region in every HS patient with retinal dystrophy, suggesting AAA-ATPase region is a hypermutable region in patients with a retinal dystrophy; third, there are no significant differences between PEX1-, PEX6-, and PEX26-associated phenotypes. CONCLUSION Next-generation sequencing is important for the diagnosis of HS. This study expands the clinical and genetic spectrum of HS, and provides additional insights into genotype-phenotype correlations, which is vital for accurate clinical practice, genetic counseling, and pathogenesis studies.
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Affiliation(s)
- Feng-Juan Gao
- Eye Institute, Eye and ENT Hospital, College of Medicine, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China.,Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, National Health Commission, Shanghai, China
| | - Fang-Yuan Hu
- Eye Institute, Eye and ENT Hospital, College of Medicine, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China.,Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, National Health Commission, Shanghai, China
| | - Ping Xu
- Eye Institute, Eye and ENT Hospital, College of Medicine, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China.,Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, National Health Commission, Shanghai, China
| | - Yu-He Qi
- Eye Institute, Eye and ENT Hospital, College of Medicine, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China.,Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, National Health Commission, Shanghai, China
| | - Jian-Kang Li
- BGI-Shenzhen, Shenzhen, China.,Department of Computer Science, City University of Hong Kong, 83 Tat Chee Ave, Kowloon, Hong Kong
| | - Yong-Jin Zhang
- Eye Institute, Eye and ENT Hospital, College of Medicine, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China.,Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, National Health Commission, Shanghai, China
| | - Fang Chen
- BGI-Shenzhen, Shenzhen, China.,Laboratory of Genomics and Molecular Biomedicine, Department of Biology, University of Copenhagen, Copenhagen, Denmark.,Shenzhen Engineering Laboratory for Birth Defects Screening, BGI-Shenzhen, Shenzhen, China
| | - Qing Chang
- Eye Institute, Eye and ENT Hospital, College of Medicine, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China.,Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, National Health Commission, Shanghai, China
| | - Fang Song
- Eye Institute, Eye and ENT Hospital, College of Medicine, Fudan University, Shanghai, China
| | | | - Ge-Zhi Xu
- Eye Institute, Eye and ENT Hospital, College of Medicine, Fudan University, Shanghai, China. .,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China. .,Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, National Health Commission, Shanghai, China.
| | - Ji-Hong Wu
- Eye Institute, Eye and ENT Hospital, College of Medicine, Fudan University, Shanghai, China. .,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China. .,Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, National Health Commission, Shanghai, China.
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24
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A Mechanistic Perspective on PEX1 and PEX6, Two AAA+ Proteins of the Peroxisomal Protein Import Machinery. Int J Mol Sci 2019; 20:ijms20215246. [PMID: 31652724 PMCID: PMC6862443 DOI: 10.3390/ijms20215246] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 10/18/2019] [Accepted: 10/21/2019] [Indexed: 12/11/2022] Open
Abstract
In contrast to many protein translocases that use ATP or GTP hydrolysis as the driving force to transport proteins across biological membranes, the peroxisomal matrix protein import machinery relies on a regulated self-assembly mechanism for this purpose and uses ATP hydrolysis only to reset its components. The ATP-dependent protein complex in charge of resetting this machinery—the Receptor Export Module (REM)—comprises two members of the “ATPases Associated with diverse cellular Activities” (AAA+) family, PEX1 and PEX6, and a membrane protein that anchors the ATPases to the organelle membrane. In recent years, a large amount of data on the structure/function of the REM complex has become available. Here, we discuss the main findings and their mechanistic implications.
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25
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Schieferdecker A, Wendler P. Structural Mapping of Missense Mutations in the Pex1/Pex6 Complex. Int J Mol Sci 2019; 20:ijms20153756. [PMID: 31374812 PMCID: PMC6696164 DOI: 10.3390/ijms20153756] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 07/25/2019] [Accepted: 07/26/2019] [Indexed: 01/05/2023] Open
Abstract
Peroxisome biogenesis disorders (PBDs) are nontreatable hereditary diseases with a broad range of severity. Approximately 65% of patients are affected by mutations in the peroxins Pex1 and Pex6. The proteins form the heteromeric Pex1/Pex6 complex, which is important for protein import into peroxisomes. To date, no structural data are available for this AAA+ ATPase complex. However, a wealth of information can be transferred from low-resolution structures of the yeast scPex1/scPex6 complex and homologous, well-characterized AAA+ ATPases. We review the abundant records of missense mutations described in PBD patients with the aim to classify and rationalize them by mapping them onto a homology model of the human Pex1/Pex6 complex. Several mutations concern functionally conserved residues that are implied in ATP hydrolysis and substrate processing. Contrary to fold destabilizing mutations, patients suffering from function-impairing mutations may not benefit from stabilizing agents, which have been reported as potential therapeutics for PBD patients.
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Affiliation(s)
- Anne Schieferdecker
- Institute of Biochemistry and Biology, University of Potsdam, D-14476 Potsdam, Germany
| | - Petra Wendler
- Institute of Biochemistry and Biology, University of Potsdam, D-14476 Potsdam, Germany.
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26
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Wangtiraumnuay N, Alnabi WA, Tsukikawa M, Thau A, Capasso J, Sharony R, Inglehearn CF, Levin AV. Ophthalmic manifestations of Heimler syndrome due to PEX6 mutations. Ophthalmic Genet 2019; 39:384-390. [PMID: 29676688 DOI: 10.1080/13816810.2018.1432063] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND/AIMS Pigmentary retinal dystrophy and macular dystrophy have been previously reported in Heimler syndrome due to mutations in PEX1. Here we reported the ocular manifestations in Heimler syndrome due to mutations in PEX6. MATERIALS AND METHODS Medical records were reviewed to identify patient demographics, ophthalmic and systemic findings, and results of diagnostic testing including whole genome sequencing. RESULTS Patient 1 is 12-year-old boy with a novel mutation c.275T>G (p.Val92Gly) and known mutation c.1802G>A (p.Arg601Gln) in PEX6. Patient 2 is a 7-year-old girl with the same known c.1802G>A (p.Arg601Gln) mutation and another novel missense mutation c.296G>T (p.Arg99Leu). Both patients exhibited a pigmentary retinopathy. Visual acuity in patient 1 was 20/80 and 20/25 following treatment of intraretinal cystoid spaces with carbonic anhydrase inhibitors, while patient 2 had visual acuity of 20/20 in both eyes without intraretinal cysts. Fundus autofluorescence showed a multitude of hyperfluorescent deposits in the paramacular area of both eyes. OCTs revealed significant depletion of photoreceptors in both patients and macular intraretinal cystoid spaces in one patient. Full field electroretinograms showed normal or abnormal photopic but normal scotopic responses. Multifocal electroretinograms were abnormal. CONCLUSIONS Heimler syndrome due to biallelic PEX6 mutations demonstrates a macular dystrophy with characteristic fundus autofluorescence and may be complicated by intraretinal cystoid spaces.
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Affiliation(s)
- Nutsuchar Wangtiraumnuay
- a Wills Eye Hospital , Philadelphia , PA , USA.,b Department of Ophthalmology , Queen Sirikit National Institute of Child Health , Bangkok , Thailand
| | | | - Mai Tsukikawa
- c Sidney Kimmel Medical College at Thomas Jefferson University , Philadelphia , PA , USA
| | - Avrey Thau
- c Sidney Kimmel Medical College at Thomas Jefferson University , Philadelphia , PA , USA
| | | | - Reuven Sharony
- d The Genetic Institute and Obstetrics and Gynecology Department, Meir Medical Center affiliated with the Sackler Faculty of Medicine , Tel Aviv University , Kfar Saba , Israel
| | - Chris F Inglehearn
- e Leeds Institute of Biomedical and Clinical Sciences, St. James's University Hospital, University of Leeds , Leeds , UK
| | - Alex V Levin
- a Wills Eye Hospital , Philadelphia , PA , USA.,c Sidney Kimmel Medical College at Thomas Jefferson University , Philadelphia , PA , USA
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27
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Abstract
Peroxisomes are key metabolic organelles, which contribute to cellular lipid metabolism, e.g. the β-oxidation of fatty acids and the synthesis of myelin sheath lipids, as well as cellular redox balance. Peroxisomal dysfunction has been linked to severe metabolic disorders in man, but peroxisomes are now also recognized as protective organelles with a wider significance in human health and potential impact on a large number of globally important human diseases such as neurodegeneration, obesity, cancer, and age-related disorders. Therefore, the interest in peroxisomes and their physiological functions has significantly increased in recent years. In this review, we intend to highlight recent discoveries, advancements and trends in peroxisome research, and present an update as well as a continuation of two former review articles addressing the unsolved mysteries of this astonishing organelle. We summarize novel findings on the biological functions of peroxisomes, their biogenesis, formation, membrane dynamics and division, as well as on peroxisome-organelle contacts and cooperation. Furthermore, novel peroxisomal proteins and machineries at the peroxisomal membrane are discussed. Finally, we address recent findings on the role of peroxisomes in the brain, in neurological disorders, and in the development of cancer.
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Affiliation(s)
- Markus Islinger
- Institute of Neuroanatomy, Center for Biomedicine and Medical Technology Mannheim, Medical Faculty Manheim, University of Heidelberg, 68167, Mannheim, Germany
| | - Alfred Voelkl
- Institute for Anatomy and Cell Biology, University of Heidelberg, 69120, Heidelberg, Germany
| | - H Dariush Fahimi
- Institute for Anatomy and Cell Biology, University of Heidelberg, 69120, Heidelberg, Germany
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28
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Chemically monoubiquitinated PEX5 binds to the components of the peroxisomal docking and export machinery. Sci Rep 2018; 8:16014. [PMID: 30375424 PMCID: PMC6207756 DOI: 10.1038/s41598-018-34200-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 10/12/2018] [Indexed: 02/05/2023] Open
Abstract
Peroxisomal matrix proteins contain either a peroxisomal targeting sequence 1 (PTS1) or a PTS2 that are recognized by the import receptors PEX5 and PEX7, respectively. PEX5 transports the PTS1 proteins and the PEX7/PTS2 complex to the docking translocation module (DTM) at the peroxisomal membrane. After cargo release PEX5 is monoubiquitinated and extracted from the peroxisomal membrane by the receptor export machinery (REM) comprising PEX26 and the AAA ATPases PEX1 and PEX6. Here, we investigated the protein interactions of monoubiquitinated PEX5 with the docking proteins PEX13, PEX14 and the REM. “Click” chemistry was used to synthesise monoubiquitinated recombinant PEX5. We found that monoubiquitinated PEX5 binds the PEX7/PTS2 complex and restores PTS2 protein import in vivo in ΔPEX5 fibroblasts. In vitro pull-down assays revealed an interaction of recombinant PEX5 and monoubiquitinated PEX5 with PEX13, PEX14 and with the REM components PEX1, PEX6 and PEX26. The interactions with the docking proteins were independent of the PEX5 ubiquitination status whereas the interactions with the REM components were increased when PEX5 is ubiquitinated.
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29
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MacLean GE, Argyriou C, Di Pietro E, Sun X, Birjandian S, Saberian P, Hacia JG, Braverman NE. Zellweger spectrum disorder patient-derived fibroblasts with the PEX1-Gly843Asp allele recover peroxisome functions in response to flavonoids. J Cell Biochem 2018; 120:3243-3258. [PMID: 30362618 DOI: 10.1002/jcb.27591] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 08/08/2018] [Indexed: 01/03/2023]
Abstract
Zellweger spectrum disorder (ZSD) results from biallelic mutations in PEX genes required for peroxisome biogenesis. PEX1-G843D is a common hypomorphic allele in the patient population that is associated with milder disease. In prior work using a PEX1-G843D/null patient fibroblast line expressing a green fluorescent protein (GFP) reporter with a peroxisome-targeting signal (GFP-PTS1), we demonstrated that treatments with the chemical chaperone betaine and flavonoid acacetin diacetate recovered peroxisome functions. To identify more effective compounds for preclinical investigation, we evaluated 54 flavonoids using this cell-based phenotype assay. Diosmetin showed the most promising combination of potency and efficacy (EC50 2.5 µM). All active 5',7'-dihydroxyflavones showed greater average efficacy than their corresponding flavonols, whereas the corresponding flavanones, isoflavones, and chalcones tested were inactive. Additional treatment with the proteostasis regulator bortezomib increased the percentage of import-rescued cells over treatment with flavonoids alone. Cotreatments of diosmetin and betaine showed the most robust additive effects, as confirmed by three independent functional assays in primary PEX1-G843D patient cells, but neither agent was active alone or in combination in patient cells homozygous for the PEX1 c.2097_2098insT null allele. Moreover, diosmetin treatment increased PEX1, PEX6, and PEX5 protein levels in PEX1-G843D patient cells, but none of these proteins increased in PEX1 null cells. We propose that diosmetin acts as a pharmacological chaperone that improves the stability, conformation, and functions of PEX1/PEX6 exportomer complexes required for peroxisome assembly. We suggest that diosmetin, in clinical use for chronic venous disease, and related flavonoids warrant further preclinical investigation for the treatment of PEX1-G843D-associated ZSD.
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Affiliation(s)
- Gillian E MacLean
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada
| | - Catherine Argyriou
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada
| | - Erminia Di Pietro
- Department of Pediatrics, Research Institute of the McGill University Health Center, Montreal, Quebec, Canada
| | - Xuting Sun
- Department of Biotechnology, McGill University, Montreal, Quebec, Canada
| | - Sara Birjandian
- Department of Biotechnology, McGill University, Montreal, Quebec, Canada
| | - Panteha Saberian
- Department of Biotechnology, McGill University, Montreal, Quebec, Canada
| | - Joseph G Hacia
- Department of Biochemistry and Molecular Medicine, Keck School of Medicine, Los Angeles, California
| | - Nancy E Braverman
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada.,Department of Pediatrics, Research Institute of the McGill University Health Center, Montreal, Quebec, Canada
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30
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Guder P, Lotz-Havla AS, Woidy M, Reiß DD, Danecka MK, Schatz UA, Becker M, Ensenauer R, Pagel P, Büttner L, Muntau AC, Gersting SW. Isoform-specific domain organization determines conformation and function of the peroxisomal biogenesis factor PEX26. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1866:518-531. [PMID: 30366024 DOI: 10.1016/j.bbamcr.2018.10.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 10/11/2018] [Accepted: 10/18/2018] [Indexed: 10/28/2022]
Abstract
Peroxisomal biogenesis factor PEX26 is a membrane anchor for the multi-subunit PEX1-PEX6 protein complex that controls ubiquitination and dislocation of PEX5 cargo receptors for peroxisomal matrix protein import. PEX26 associates with the peroxisomal translocation pore via PEX14 and a splice variant (PEX26Δex5) of unknown function has been reported. Here, we demonstrate PEX26 homooligomerization mediated by two heptad repeat domains adjacent to the transmembrane domain. We show that isoform-specific domain organization determines PEX26 oligomerization and impacts peroxisomal β-oxidation and proliferation. PEX26 and PEX26Δex5 displayed different patterns of interaction with PEX2-PEX10 or PEX13-PEX14 complexes, which relate to distinct pre-peroxisomes in the de novo synthesis pathway. Our data support an alternative PEX14-dependent mechanism of peroxisomal membrane association for the splice variant, which lacks a transmembrane domain. Structure-function relationships of PEX26 isoforms explain an extended function in peroxisomal homeostasis and these findings may improve our understanding of the broad phenotype of PEX26-associated human disorders.
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Affiliation(s)
- Philipp Guder
- University Children's Research@Kinder-UKE, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany; Children's Hospital, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Amelie S Lotz-Havla
- Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, 80337 Munich, Germany
| | - Mathias Woidy
- University Children's Research@Kinder-UKE, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany; Children's Hospital, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Dunja D Reiß
- Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, 80337 Munich, Germany
| | - Marta K Danecka
- University Children's Research@Kinder-UKE, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Ulrich A Schatz
- Department for Medical Genetics, Molecular and Clinical Pharmacology, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Marc Becker
- Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, 80337 Munich, Germany; Labor Becker Olgemöller und Kollegen, 81671 Munich, Germany
| | - Regina Ensenauer
- Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, 80337 Munich, Germany; Experimental Pediatrics, Department of General Pediatrics, Neonatology and Pediatric Cardiology, University Children's Hospital, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Philipp Pagel
- Lehrstuhl für Genomorientierte Bioinformatik, Technische Universität, 85350 Freising, Germany; numares GmbH, Josef-Engert-Str. 9, 93053 Regensburg, Germany
| | - Lars Büttner
- Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, 80337 Munich, Germany
| | - Ania C Muntau
- Children's Hospital, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Søren W Gersting
- University Children's Research@Kinder-UKE, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany; Children's Hospital, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
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31
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Schwerter D, Grimm I, Girzalsky W, Erdmann R. Receptor recognition by the peroxisomal AAA complex depends on the presence of the ubiquitin moiety and is mediated by Pex1p. J Biol Chem 2018; 293:15458-15470. [PMID: 30097517 DOI: 10.1074/jbc.ra118.003936] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 07/23/2018] [Indexed: 01/14/2023] Open
Abstract
The receptor cycle of type I peroxisomal matrix protein import is completed by ubiquitination of the membrane-bound peroxisome biogenesis factor 5 (Pex5p) and its subsequent export back to the cytosol. The receptor export is the only ATP-dependent step of the whole process and is facilitated by two members of the AAA family of proteins (ATPases associated with various cellular activities), namely Pex1p and Pex6p. To gain further insight into substrate recognition by the AAA complex, we generated an N-terminally linked ubiquitin-Pex5p fusion protein. This fusion protein displayed biological activity because it is able to functionally complement a PEX5-deletion in Saccharomyces cerevisiae. In vitro assays revealed its interaction at WT level with the native cargo protein Pcs60p and Pex14p, a constituent of the receptor docking complex. We also demonstrate in vitro deubiquitination by the deubiquitinating enzyme Ubp15p. In vitro pulldown assays and cross-linking studies demonstrate that Pex5p recognition by the AAA complex depends on the presence of the ubiquitin moiety and is mediated by Pex1p.
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Affiliation(s)
- Daniel Schwerter
- From the Institute of Biochemistry and Pathobiochemistry, Faculty of Medicine, Systems Biochemistry, Ruhr-University Bochum, D-44780 Bochum, Germany
| | - Immanuel Grimm
- From the Institute of Biochemistry and Pathobiochemistry, Faculty of Medicine, Systems Biochemistry, Ruhr-University Bochum, D-44780 Bochum, Germany
| | - Wolfgang Girzalsky
- From the Institute of Biochemistry and Pathobiochemistry, Faculty of Medicine, Systems Biochemistry, Ruhr-University Bochum, D-44780 Bochum, Germany
| | - Ralf Erdmann
- From the Institute of Biochemistry and Pathobiochemistry, Faculty of Medicine, Systems Biochemistry, Ruhr-University Bochum, D-44780 Bochum, Germany
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32
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Pedrosa AG, Francisco T, Bicho D, Dias AF, Barros-Barbosa A, Hagmann V, Dodt G, Rodrigues TA, Azevedo JE. Peroxisomal monoubiquitinated PEX5 interacts with the AAA ATPases PEX1 and PEX6 and is unfolded during its dislocation into the cytosol. J Biol Chem 2018; 293:11553-11563. [PMID: 29884772 DOI: 10.1074/jbc.ra118.003669] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 05/28/2018] [Indexed: 11/06/2022] Open
Abstract
PEX1 and PEX6 are two members of the ATPases associated with diverse cellular activities (AAA) family and the core components of the receptor export module of the peroxisomal matrix protein import machinery. Their role is to extract monoubiquitinated PEX5, the peroxisomal protein-shuttling receptor, from the peroxisomal membrane docking/translocation module (DTM), so that a new cycle of protein transportation can start. Recent data have shown that PEX1 and PEX6 form a heterohexameric complex that unfolds substrates by processive threading. However, whether the natural substrate of the PEX1-PEX6 complex is monoubiquitinated PEX5 (Ub-PEX5) itself or some Ub-PEX5-interacting component(s) of the DTM remains unknown. In this work, we used an established cell-free in vitro system coupled with photoaffinity cross-linking and protein PEGylation assays to address this problem. We provide evidence suggesting that DTM-embedded Ub-PEX5 interacts directly with both PEX1 and PEX6 through its ubiquitin moiety and that the PEX5 polypeptide chain is globally unfolded during the ATP-dependent extraction event. These findings strongly suggest that DTM-embedded Ub-PEX5 is a bona fide substrate of the PEX1-PEX6 complex.
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Affiliation(s)
- Ana G Pedrosa
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
| | - Tânia Francisco
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
| | - Diana Bicho
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
| | - Ana F Dias
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
| | - Aurora Barros-Barbosa
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
| | - Vera Hagmann
- Interfakultäres Institut für Biochemie, Universität Tübingen, Hoppe Seyler Strasse 4, 72076 Tübingen, Germany
| | - Gabriele Dodt
- Interfakultäres Institut für Biochemie, Universität Tübingen, Hoppe Seyler Strasse 4, 72076 Tübingen, Germany
| | - Tony A Rodrigues
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
| | - Jorge E Azevedo
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal.
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33
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Law KB, Bronte-Tinkew D, Di Pietro E, Snowden A, Jones RO, Moser A, Brumell JH, Braverman N, Kim PK. The peroxisomal AAA ATPase complex prevents pexophagy and development of peroxisome biogenesis disorders. Autophagy 2018; 13:868-884. [PMID: 28521612 PMCID: PMC5446072 DOI: 10.1080/15548627.2017.1291470] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Peroxisome biogenesis disorders (PBDs) are metabolic disorders caused by the loss of peroxisomes. The majority of PBDs result from mutation in one of 3 genes that encode for the peroxisomal AAA ATPase complex (AAA-complex) required for cycling PEX5 for peroxisomal matrix protein import. Mutations in these genes are thought to result in a defect in peroxisome assembly by preventing the import of matrix proteins. However, we show here that loss of the AAA-complex does not prevent matrix protein import, but instead causes an upregulation of peroxisome degradation by macroautophagy, or pexophagy. The loss of AAA-complex function in cells results in the accumulation of ubiquitinated PEX5 on the peroxisomal membrane that signals pexophagy. Inhibiting autophagy by genetic or pharmacological approaches rescues peroxisome number, protein import and function. Our findings suggest that the peroxisomal AAA-complex is required for peroxisome quality control, whereas its absence results in the selective degradation of the peroxisome. Thus the loss of peroxisomes in PBD patients with mutations in their peroxisomal AAA-complex is a result of increased pexophagy. Our study also provides a framework for the development of novel therapeutic treatments for PBDs.
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Affiliation(s)
- Kelsey B Law
- a Cell Biology Program , Hospital for Sick Children, Peter Gilgan Centre for Research and Learning , Toronto , ON , Canada.,b Department of Biochemistry , University of Toronto , Toronto , ON , Canada
| | - Dana Bronte-Tinkew
- a Cell Biology Program , Hospital for Sick Children, Peter Gilgan Centre for Research and Learning , Toronto , ON , Canada
| | - Erminia Di Pietro
- c Research Institute of the MUHC and McGill University , Montreal , QC , Canada
| | - Ann Snowden
- d Kennedy Krieger Institute , Baltimore , MD , USA
| | | | - Ann Moser
- d Kennedy Krieger Institute , Baltimore , MD , USA
| | - John H Brumell
- a Cell Biology Program , Hospital for Sick Children, Peter Gilgan Centre for Research and Learning , Toronto , ON , Canada.,e Department of Molecular Genetics , University of Toronto , Toronto , ON , Canada.,f Institute of Medical Science, University of Toronto , Toronto , ON , Canada.,g SickKids IBD Centre , Hospital for Sick Children , Toronto , ON , Canada
| | - Nancy Braverman
- c Research Institute of the MUHC and McGill University , Montreal , QC , Canada
| | - Peter K Kim
- a Cell Biology Program , Hospital for Sick Children, Peter Gilgan Centre for Research and Learning , Toronto , ON , Canada.,b Department of Biochemistry , University of Toronto , Toronto , ON , Canada
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34
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A pex1 missense mutation improves peroxisome function in a subset of Arabidopsis pex6 mutants without restoring PEX5 recycling. Proc Natl Acad Sci U S A 2018; 115:E3163-E3172. [PMID: 29555730 DOI: 10.1073/pnas.1721279115] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Peroxisomes are eukaryotic organelles critical for plant and human development because they house essential metabolic functions, such as fatty acid β-oxidation. The interacting ATPases PEX1 and PEX6 contribute to peroxisome function by recycling PEX5, a cytosolic receptor needed to import proteins targeted to the peroxisomal matrix. Arabidopsis pex6 mutants exhibit low PEX5 levels and defects in peroxisomal matrix protein import, oil body utilization, peroxisomal metabolism, and seedling growth. These defects are hypothesized to stem from impaired PEX5 retrotranslocation leading to PEX5 polyubiquitination and consequent degradation of PEX5 via the proteasome or of the entire organelle via autophagy. We recovered a pex1 missense mutation in a screen for second-site suppressors that restore growth to the pex6-1 mutant. Surprisingly, this pex1-1 mutation ameliorated the metabolic and physiological defects of pex6-1 without restoring PEX5 levels. Similarly, preventing autophagy by introducing an atg7-null allele partially rescued pex6-1 physiological defects without restoring PEX5 levels. atg7 synergistically improved matrix protein import in pex1-1 pex6-1, implying that pex1-1 improves peroxisome function in pex6-1 without impeding autophagy of peroxisomes (i.e., pexophagy). pex1-1 differentially improved peroxisome function in various pex6 alleles but worsened the physiological and molecular defects of a pex26 mutant, which is defective in the tether anchoring the PEX1-PEX6 hexamer to the peroxisome. Our results support the hypothesis that, beyond PEX5 recycling, PEX1 and PEX6 have additional functions in peroxisome homeostasis and perhaps in oil body utilization.
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35
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The peroxisomal AAA-ATPase Pex1/Pex6 unfolds substrates by processive threading. Nat Commun 2018; 9:135. [PMID: 29321502 PMCID: PMC5762779 DOI: 10.1038/s41467-017-02474-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 12/04/2017] [Indexed: 12/15/2022] Open
Abstract
Pex1 and Pex6 form a heterohexameric motor essential for peroxisome biogenesis and function, and mutations in these AAA-ATPases cause most peroxisome-biogenesis disorders in humans. The tail-anchored protein Pex15 recruits Pex1/Pex6 to the peroxisomal membrane, where it performs an unknown function required for matrix-protein import. Here we determine that Pex1/Pex6 from S. cerevisiae is a protein translocase that unfolds Pex15 in a pore-loop-dependent and ATP-hydrolysis-dependent manner. Our structural studies of Pex15 in isolation and in complex with Pex1/Pex6 illustrate that Pex15 binds the N-terminal domains of Pex6, before its C-terminal disordered region engages with the pore loops of the motor, which then processively threads Pex15 through the central pore. Furthermore, Pex15 directly binds the cargo receptor Pex5, linking Pex1/Pex6 to other components of the peroxisomal import machinery. Our results thus support a role of Pex1/Pex6 in mechanical unfolding of peroxins or their extraction from the peroxisomal membrane during matrix-protein import. Pex1 and Pex6 form a heterohexameric Type-2 AAA-ATPase motor whose function in peroxisomal matrix-protein import is still debated. Here, the authors combine structural, biochemical, and cell-biological approaches to show that Pex1/Pex6 is a protein unfoldase, which supports a role in mechanical unfolding of peroxin proteins.
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36
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Kao YT, Gonzalez KL, Bartel B. Peroxisome Function, Biogenesis, and Dynamics in Plants. PLANT PHYSIOLOGY 2018; 176:162-177. [PMID: 29021223 PMCID: PMC5761812 DOI: 10.1104/pp.17.01050] [Citation(s) in RCA: 109] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 10/09/2017] [Indexed: 05/19/2023]
Abstract
Recent advances highlight understanding of the diversity of peroxisome contributions to plant biology and the mechanisms through which these essential organelles are generated.
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Affiliation(s)
- Yun-Ting Kao
- Department of Biosciences, Rice University, Houston, Texas 77005
| | - Kim L Gonzalez
- Department of Biosciences, Rice University, Houston, Texas 77005
| | - Bonnie Bartel
- Department of Biosciences, Rice University, Houston, Texas 77005
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37
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Kalel VC, Erdmann R. Unraveling of the Structure and Function of Peroxisomal Protein Import Machineries. Subcell Biochem 2018; 89:299-321. [PMID: 30378029 DOI: 10.1007/978-981-13-2233-4_13] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Peroxisomes are dynamic organelles of eukaryotic cells performing a wide range of functions including fatty acid oxidation, peroxide detoxification and ether-lipid synthesis in mammals. Peroxisomes lack their own DNA and therefore have to import proteins post-translationally. Peroxisomes can import folded, co-factor bound and even oligomeric proteins. The involvement of cycling receptors is a special feature of peroxisomal protein import. Complex machineries of peroxin (PEX) proteins mediate peroxisomal matrix and membrane protein import. Identification of PEX genes was dominated by forward genetic techniques in the early 90s. However, recent developments in proteomic techniques has revolutionized the detailed characterization of peroxisomal protein import. Here, we summarize the current knowledge on peroxisomal protein import with emphasis on the contribution of proteomic approaches to our understanding of the composition and function of the peroxisomal protein import machineries.
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Affiliation(s)
- Vishal C Kalel
- Department of Systems Biochemistry, Faculty of Medicine, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Universitätsstr. 150, 44801, Bochum, Germany.
| | - Ralf Erdmann
- Department of Systems Biochemistry, Faculty of Medicine, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Universitätsstr. 150, 44801, Bochum, Germany
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38
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Falkenberg KD, Braverman NE, Moser AB, Steinberg SJ, Klouwer FCC, Schlüter A, Ruiz M, Pujol A, Engvall M, Naess K, van Spronsen F, Körver-Keularts I, Rubio-Gozalbo ME, Ferdinandusse S, Wanders RJA, Waterham HR. Allelic Expression Imbalance Promoting a Mutant PEX6 Allele Causes Zellweger Spectrum Disorder. Am J Hum Genet 2017; 101:965-976. [PMID: 29220678 DOI: 10.1016/j.ajhg.2017.11.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 11/14/2017] [Indexed: 01/14/2023] Open
Abstract
Zellweger spectrum disorders (ZSDs) are autosomal-recessive disorders that are caused by defects in peroxisome biogenesis due to bi-allelic mutations in any of 13 different PEX genes. Here, we identified seven unrelated individuals affected with an apparent dominant ZSD in whom a heterozygous mutant PEX6 allele (c.2578C>T [p.Arg860Trp]) was overrepresented due to allelic expression imbalance (AEI). We demonstrated that AEI of PEX6 is a common phenomenon and is correlated with heterozygosity for a frequent variant in the 3' untranslated region (UTR) of the mutant allele, which disrupts the most distal of two polyadenylation sites. Asymptomatic parents, who were heterozygous for PEX c.2578C>T, did not show AEI and were homozygous for the 3' UTR variant. Overexpression models confirmed that the overrepresentation of the pathogenic PEX6 c.2578T variant compared to wild-type PEX6 c.2578C results in a peroxisome biogenesis defect and thus constitutes the cause of disease in the affected individuals. AEI promoting the overrepresentation of a mutant allele might also play a role in other autosomal-recessive disorders, in which only one heterozygous pathogenic variant is identified.
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Affiliation(s)
- Kim D Falkenberg
- Laboratory Genetic Metabolic Diseases, Academic Medical Center, University of Amsterdam, Amsterdam 1105 AZ, the Netherlands
| | - Nancy E Braverman
- Department of Pediatrics and Human Genetics, Research Institute of the McGill University Health Center and McGill University, Montreal, QC H4A 3J1, Canada
| | - Ann B Moser
- Kennedy Krieger Institute, Baltimore, MD 21205, USA
| | - Steven J Steinberg
- Institute of Genetic Medicine and Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Femke C C Klouwer
- Laboratory Genetic Metabolic Diseases, Academic Medical Center, University of Amsterdam, Amsterdam 1105 AZ, the Netherlands; Department of Pediatric Neurology, Emma Children's Hospital, Academic Medical Center, University of Amsterdam, Amsterdam 1105 AZ, the Netherlands
| | - Agatha Schlüter
- Neurometabolic Diseases Laboratory, Institute of Neuropathology, IDIBELL, Barcelona 08908, Spain; CIBERER U759, Center for Biomedical Research on Rare Diseases, Valencia 46010, Spain
| | - Montserrat Ruiz
- Neurometabolic Diseases Laboratory, Institute of Neuropathology, IDIBELL, Barcelona 08908, Spain; CIBERER U759, Center for Biomedical Research on Rare Diseases, Valencia 46010, Spain
| | - Aurora Pujol
- Neurometabolic Diseases Laboratory, Institute of Neuropathology, IDIBELL, Barcelona 08908, Spain; CIBERER U759, Center for Biomedical Research on Rare Diseases, Valencia 46010, Spain; Catalan Institution of Research and Advanced Studies (ICREA), Barcelona 08010, Spain
| | - Martin Engvall
- Centre for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm 171 77, Sweden; Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm 171 76, Sweden
| | - Karin Naess
- Centre for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm 171 77, Sweden; Department of Medical Biochemistry and Biophysics, Division of Molecular Metabolism, Karolinska Institutet, Stockholm 171 77, Sweden
| | - FrancJan van Spronsen
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Beatrix Children's Hospital, Groningen 9700 RB, the Netherlands
| | - Irene Körver-Keularts
- Department of Pediatrics, Maastricht University Medical Center, Maastricht 6211 LK, the Netherlands
| | - M Estela Rubio-Gozalbo
- Department of Pediatrics, Maastricht University Medical Center, Maastricht 6211 LK, the Netherlands; Laboratory Genetic Metabolic Diseases, Maastricht University Medical Center, Maastricht 6211 LK, the Netherlands
| | - Sacha Ferdinandusse
- Laboratory Genetic Metabolic Diseases, Academic Medical Center, University of Amsterdam, Amsterdam 1105 AZ, the Netherlands
| | - Ronald J A Wanders
- Laboratory Genetic Metabolic Diseases, Academic Medical Center, University of Amsterdam, Amsterdam 1105 AZ, the Netherlands
| | - Hans R Waterham
- Laboratory Genetic Metabolic Diseases, Academic Medical Center, University of Amsterdam, Amsterdam 1105 AZ, the Netherlands.
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Gonzalez KL, Fleming WA, Kao YT, Wright ZJ, Venkova SV, Ventura MJ, Bartel B. Disparate peroxisome-related defects in Arabidopsis pex6 and pex26 mutants link peroxisomal retrotranslocation and oil body utilization. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 92:110-128. [PMID: 28742939 PMCID: PMC5605450 DOI: 10.1111/tpj.13641] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 06/22/2017] [Accepted: 07/18/2017] [Indexed: 05/29/2023]
Abstract
Catabolism of fatty acids stored in oil bodies is essential for seed germination and seedling development in Arabidopsis. This fatty acid breakdown occurs in peroxisomes, organelles that sequester oxidative reactions. Import of peroxisomal enzymes is facilitated by peroxins including PEX5, a receptor that delivers cargo proteins from the cytosol to the peroxisomal matrix. After cargo delivery, a complex of the PEX1 and PEX6 ATPases and the PEX26 tail-anchored membrane protein removes ubiquitinated PEX5 from the peroxisomal membrane. We identified Arabidopsis pex6 and pex26 mutants by screening for inefficient seedling β-oxidation phenotypes. The mutants displayed distinct defects in growth, response to a peroxisomally metabolized auxin precursor, and peroxisomal protein import. The low PEX5 levels in these mutants were increased by treatment with a proteasome inhibitor or by combining pex26 with peroxisome-associated ubiquitination machinery mutants, suggesting that ubiquitinated PEX5 is degraded by the proteasome when the function of PEX6 or PEX26 is reduced. Combining pex26 with mutations that increase PEX5 levels either worsened or improved pex26 physiological and molecular defects, depending on the introduced lesion. Moreover, elevating PEX5 levels via a 35S:PEX5 transgene exacerbated pex26 defects and ameliorated the defects of only a subset of pex6 alleles, implying that decreased PEX5 is not the sole molecular deficiency in these mutants. We found peroxisomes clustered around persisting oil bodies in pex6 and pex26 seedlings, suggesting a role for peroxisomal retrotranslocation machinery in oil body utilization. The disparate phenotypes of these pex alleles may reflect unanticipated functions of the peroxisomal ATPase complex.
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Affiliation(s)
| | | | | | | | | | | | - Bonnie Bartel
- Corresponding author: Bonnie Bartel, Department of Biosciences, MS-140, Rice University, 6100 Main St., Houston TX, USA. Phone: 713-348-5602, Fax: 713-348-5154;
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40
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Wang W, Subramani S. Role of PEX5 ubiquitination in maintaining peroxisome dynamics and homeostasis. Cell Cycle 2017; 16:2037-2045. [PMID: 28933989 PMCID: PMC5731411 DOI: 10.1080/15384101.2017.1376149] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 08/24/2017] [Accepted: 09/01/2017] [Indexed: 12/15/2022] Open
Abstract
Peroxisomes are essential and dynamic organelles that allow cells to rapidly adapt and cope with changing environments and/or physiological conditions by modulation of both peroxisome biogenesis and turnover. Peroxisome biogenesis involves the assembly of peroxisome membranes and the import of peroxisomal matrix proteins. The latter depends on the receptor, PEX5, which recognizes peroxisomal matrix proteins in the cytosol directly or indirectly, and transports them to the peroxisomal lumen. In this review, we discuss the role of PEX5 ubiquitination in both peroxisome biogenesis and turnover, specifically in PEX5 receptor recycling, stability and abundance, as well as its role in pexophagy (autophagic degradation of peroxisomes).
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Affiliation(s)
- Wei Wang
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA, USA
| | - Suresh Subramani
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA, USA
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41
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Francisco T, Rodrigues TA, Dias AF, Barros-Barbosa A, Bicho D, Azevedo JE. Protein transport into peroxisomes: Knowns and unknowns. Bioessays 2017; 39. [PMID: 28787099 DOI: 10.1002/bies.201700047] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Peroxisomal matrix proteins are synthesized on cytosolic ribosomes and rapidly transported into the organelle by a complex machinery. The data gathered in recent years suggest that this machinery operates through a syringe-like mechanism, in which the shuttling receptor PEX5 - the "plunger" - pushes a newly synthesized protein all the way through a peroxisomal transmembrane protein complex - the "barrel" - into the matrix of the organelle. Notably, insertion of cargo-loaded receptor into the "barrel" is an ATP-independent process, whereas extraction of the receptor back into the cytosol requires its monoubiquitination and the action of ATP-dependent mechanoenzymes. Here, we review the main data behind this model.
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Affiliation(s)
- Tânia Francisco
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - Tony A Rodrigues
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal.,Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - Ana F Dias
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal.,Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - Aurora Barros-Barbosa
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - Diana Bicho
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - Jorge E Azevedo
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal.,Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
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42
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Rinaldi MA, Fleming WA, Gonzalez KL, Park J, Ventura MJ, Patel AB, Bartel B. The PEX1 ATPase Stabilizes PEX6 and Plays Essential Roles in Peroxisome Biology. PLANT PHYSIOLOGY 2017; 174:2231-2247. [PMID: 28600347 PMCID: PMC5543962 DOI: 10.1104/pp.17.00548] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 06/07/2017] [Indexed: 05/29/2023]
Abstract
A variety of metabolic pathways are sequestered in peroxisomes, conserved organelles that are essential for human and plant survival. Peroxin (PEX) proteins generate and maintain peroxisomes. The PEX1 ATPase facilitates recycling of the peroxisome matrix protein receptor PEX5 and is the most commonly affected peroxin in human peroxisome biogenesis disorders. Here, we describe the isolation and characterization of, to our knowledge, the first Arabidopsis (Arabidopsis thaliana) pex1 missense alleles: pex1-2 and pex1-3pex1-2 displayed peroxisome-related defects accompanied by reduced PEX1 and PEX6 levels. These pex1-2 defects were exacerbated by growth at high temperature and ameliorated by growth at low temperature or by PEX6 overexpression, suggesting that PEX1 enhances PEX6 stability and vice versa. pex1-3 conferred embryo lethality when homozygous, confirming that PEX1, like several other Arabidopsis peroxins, is essential for embryogenesis. pex1-3 displayed symptoms of peroxisome dysfunction when heterozygous; this semidominance is consistent with PEX1 forming a heterooligomer with PEX6 that is poisoned by pex1-3 subunits. Blocking autophagy partially rescued PEX1/pex1-3 defects, including the restoration of normal peroxisome size, suggesting that increasing peroxisome abundance can compensate for the deficiencies caused by pex1-3 and that the enlarged peroxisomes visible in PEX1/pex1-3 may represent autophagy intermediates. Overexpressing PEX1 in wild-type plants impaired growth, suggesting that excessive PEX1 can be detrimental. Our genetic, molecular, and physiological data support the heterohexamer model of PEX1-PEX6 function in plants.
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Affiliation(s)
- Mauro A Rinaldi
- Department of BioSciences, Rice University, Houston, Texas 77005
| | | | - Kim L Gonzalez
- Department of BioSciences, Rice University, Houston, Texas 77005
| | - Jaeseok Park
- Department of BioSciences, Rice University, Houston, Texas 77005
| | | | - Ashish B Patel
- Department of BioSciences, Rice University, Houston, Texas 77005
| | - Bonnie Bartel
- Department of BioSciences, Rice University, Houston, Texas 77005
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43
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Schwerter DP, Grimm I, Platta HW, Erdmann R. ATP-driven processes of peroxisomal matrix protein import. Biol Chem 2017; 398:607-624. [PMID: 27977397 DOI: 10.1515/hsz-2016-0293] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 12/11/2016] [Indexed: 12/13/2022]
Abstract
In peroxisomal matrix protein import two processes directly depend on the binding and hydrolysis of ATP, both taking place at the late steps of the peroxisomal import cycle. First, ATP hydrolysis is required to initiate a ubiquitin-transfer cascade to modify the import (co-)receptors. These receptors display a dual localization in the cytosol and at the peroxisomal membrane, whereas only the membrane bound fraction receives the ubiquitin modification. The second ATP-dependent process of the import cycle is carried out by the two AAA+-proteins Pex1p and Pex6p. These ATPases form a heterohexameric complex, which is recruited to the peroxisomal import machinery by the membrane anchor protein Pex15p. The Pex1p/Pex6p complex recognizes the ubiquitinated import receptors, pulls them out of the membrane and releases them into the cytosol. There the deubiquitinated receptors are provided for further rounds of import. ATP binding and hydrolysis are required for Pex1p/Pex6p complex formation and receptor export. In this review, we summarize the current knowledge on the peroxisomal import cascade. In particular, we will focus on the ATP-dependent processes, which are so far best understood in the model organism Saccharomyces cerevisiae.
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Affiliation(s)
- Daniel P Schwerter
- Abteilung für Systembiochemie, Institut für Biochemie und Pathobiochemie, Medizinische Fakultät der Ruhr-Universität Bochum, Universitätsstr. 150, D-44780 Bochum
| | - Immanuel Grimm
- Abteilung für Systembiochemie, Institut für Biochemie und Pathobiochemie, Medizinische Fakultät der Ruhr-Universität Bochum, Universitätsstr. 150, D-44780 Bochum
| | - Harald W Platta
- Biochemie Intrazellulärer Transportprozesse, Medizinische Fakultät der Ruhr-Universität Bochum, D-44780 Bochum
| | - Ralf Erdmann
- Abteilung für Systembiochemie, Institut für Biochemie und Pathobiochemie, Medizinische Fakultät der Ruhr-Universität Bochum, Universitätsstr. 150, D-44780 Bochum
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44
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Saffert P, Enenkel C, Wendler P. Structure and Function of p97 and Pex1/6 Type II AAA+ Complexes. Front Mol Biosci 2017; 4:33. [PMID: 28611990 PMCID: PMC5447069 DOI: 10.3389/fmolb.2017.00033] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 05/05/2017] [Indexed: 12/16/2022] Open
Abstract
Protein complexes of the Type II AAA+ (ATPases associated with diverse cellular activities) family are typically hexamers of 80–150 kDa protomers that harbor two AAA+ ATPase domains. They form double ring assemblies flanked by associated domains, which can be N-terminal, intercalated or C-terminal to the ATPase domains. Most prominent members of this family include NSF (N-ethyl-maleimide sensitive factor), p97/VCP (valosin-containing protein), the Pex1/Pex6 complex and Hsp104 in eukaryotes and ClpB in bacteria. Tremendous efforts have been undertaken to understand the conformational dynamics of protein remodeling type II AAA+ complexes. A uniform mode of action has not been derived from these works. This review focuses on p97/VCP and the Pex1/6 complex, which both structurally remodel ubiquitinated substrate proteins. P97/VCP plays a role in many processes, including ER- associated protein degradation, and the Pex1/Pex6 complex dislocates and recycles the transport receptor Pex5 from the peroxisomal membrane during peroxisomal protein import. We give an introduction into existing knowledge about the biochemical and cellular activities of the complexes before discussing structural information. We particularly emphasize recent electron microscopy structures of the two AAA+ complexes and summarize their structural differences.
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Affiliation(s)
- Paul Saffert
- Department of Biochemistry, Institute of Biochemistry and Biology, University of PotsdamPotsdam, Germany
| | - Cordula Enenkel
- Department of Biochemistry, University of TorontoToronto, ON, Canada
| | - Petra Wendler
- Department of Biochemistry, Institute of Biochemistry and Biology, University of PotsdamPotsdam, Germany
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45
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Isolation of Native Soluble and Membrane-Bound Protein Complexes from Yeast Saccharomyces cerevisiae. Methods Mol Biol 2017; 1595:37-44. [PMID: 28409449 DOI: 10.1007/978-1-4939-6937-1_4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Immunoprecipitation is a traditional approach to isolate single proteins or native protein complexes from a complex sample mixture. The original method makes use of specific antibodies against endogenous proteins or epitope tags, which are first bound to the target protein and then isolated with protein A beads. An advancement of this method is the application of a protein A tag fused to the target protein and the affinity-purification of the tagged protein with human Immunoglobulin G chemically cross-linked to a sepharose matrix. This method will be described exemplified by the purification of protein complexes of the peroxisomal membrane from yeast Saccharomyces cerevisiae.
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46
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Bousfiha A, Bakhchane A, Charoute H, Riahi Z, Snoussi K, Rouba H, Bonnet C, Petit C, Barakat A. A novel PEX1 mutation in a Moroccan family with Zellweger spectrum disorders. Hum Genome Var 2017; 4:17009. [PMID: 28446956 PMCID: PMC5390255 DOI: 10.1038/hgv.2017.9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 02/03/2017] [Accepted: 02/07/2017] [Indexed: 01/18/2023] Open
Abstract
Mutations in the PEX1 gene are usually associated with recessive inherited diseases including Zellweger spectrum disorders. In this work, we identified a new pathogenic missense homozygous PEX1 mutation (p.Leu1026Pro, c.3077T>C) in two Moroccan syndromic deaf siblings from consanguineous parents. This variation is located in the P-loop containing nucleoside triphosphate hydrolase of protein domain and probably causes an alteration in the hydrolysis of ATP.
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Affiliation(s)
- Amale Bousfiha
- Human Molecular Genetics Laboratory, Institut Pasteur du Maroc, Casablanca, Morocco
| | - Amina Bakhchane
- Human Molecular Genetics Laboratory, Institut Pasteur du Maroc, Casablanca, Morocco
| | - Hicham Charoute
- Human Molecular Genetics Laboratory, Institut Pasteur du Maroc, Casablanca, Morocco
| | - Zied Riahi
- INSERM UMRS1120, Institut de la Vision, Paris, France.,UPMC-Sorbonnes Universités Paris VI, Paris, France
| | - Khalid Snoussi
- Human Molecular Genetics Laboratory, Institut Pasteur du Maroc, Casablanca, Morocco
| | - Hassan Rouba
- Human Molecular Genetics Laboratory, Institut Pasteur du Maroc, Casablanca, Morocco
| | - Crystel Bonnet
- INSERM UMRS1120, Institut de la Vision, Paris, France.,UPMC-Sorbonnes Universités Paris VI, Paris, France
| | - Christine Petit
- INSERM UMRS1120, Institut de la Vision, Paris, France.,UPMC-Sorbonnes Universités Paris VI, Paris, France.,Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, Paris, France.,Collège de France, Paris, France
| | - Abdelhamid Barakat
- Human Molecular Genetics Laboratory, Institut Pasteur du Maroc, Casablanca, Morocco
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47
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Characterization of the heterooligomeric red-type rubisco activase from red algae. Proc Natl Acad Sci U S A 2016; 113:14019-14024. [PMID: 27872295 DOI: 10.1073/pnas.1610758113] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The photosynthetic CO2-fixing enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) is inhibited by nonproductive binding of its substrate ribulose-1,5-bisphosphate (RuBP) and other sugar phosphates. Reactivation requires ATP-hydrolysis-powered remodeling of the inhibited complexes by diverse molecular chaperones known as rubisco activases (Rcas). Eukaryotic phytoplankton of the red plastid lineage contain so-called red-type rubiscos, some of which have been shown to possess superior kinetic properties to green-type rubiscos found in higher plants. These organisms are known to encode multiple homologs of CbbX, the α-proteobacterial red-type activase. Here we show that the gene products of two cbbX genes encoded by the nuclear and plastid genomes of the red algae Cyanidioschyzon merolae are nonfunctional in isolation, but together form a thermostable heterooligomeric Rca that can use both α-proteobacterial and red algal-inhibited rubisco complexes as a substrate. The mechanism of rubisco activation appears conserved between the bacterial and the algal systems and involves threading of the rubisco large subunit C terminus. Whereas binding of the allosteric regulator RuBP induces oligomeric transitions to the bacterial activase, it merely enhances the kinetics of ATP hydrolysis in the algal enzyme. Mutational analysis of nuclear and plastid isoforms demonstrates strong coordination between the subunits and implicates the nuclear-encoded subunit as being functionally dominant. The plastid-encoded subunit may be catalytically inert. Efforts to enhance crop photosynthesis by transplanting red algal rubiscos with enhanced kinetics will need to take into account the requirement for a compatible Rca.
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Affiliation(s)
| | - Maria Daniela D'Agostino
- McGill University Department of Human Genetics and McGill University Health Center, Department of Medical Genetics, Montreal, QC, Canada
| | - Nancy Braverman
- McGill University Department of Human Genetics and Pediatrics, and The Research Institute of the McGill University Health Centre, Montreal, QC, Canada
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49
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Kienle N, Kloepper TH, Fasshauer D. Shedding light on the expansion and diversification of the Cdc48 protein family during the rise of the eukaryotic cell. BMC Evol Biol 2016; 16:215. [PMID: 27756227 PMCID: PMC5070193 DOI: 10.1186/s12862-016-0790-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2016] [Accepted: 10/04/2016] [Indexed: 11/22/2022] Open
Abstract
Background A defining feature of eukaryotic cells is the presence of various distinct membrane-bound compartments with different metabolic roles. Material exchange between most compartments occurs via a sophisticated vesicle trafficking system. This intricate cellular architecture of eukaryotes appears to have emerged suddenly, about 2 billion years ago, from much less complex ancestors. How the eukaryotic cell acquired its internal complexity is poorly understood, partly because no prokaryotic precursors have been found for many key factors involved in compartmentalization. One exception is the Cdc48 protein family, which consists of several distinct classical ATPases associated with various cellular activities (AAA+) proteins with two consecutive AAA domains. Results Here, we have classified the Cdc48 family through iterative use of hidden Markov models and tree building. We found only one type, Cdc48, in prokaryotes, although a set of eight diverged members that function at distinct subcellular compartments were retrieved from eukaryotes and were probably present in the last eukaryotic common ancestor (LECA). Pronounced changes in sequence and domain structure during the radiation into the LECA set are delineated. Moreover, our analysis brings to light lineage-specific losses and duplications that often reflect important biological changes. Remarkably, we also found evidence for internal duplications within the LECA set that probably occurred during the rise of the eukaryotic cell. Conclusions Our analysis corroborates the idea that the diversification of the Cdc48 family is closely intertwined with the development of the compartments of the eukaryotic cell. Electronic supplementary material The online version of this article (doi:10.1186/s12862-016-0790-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Nickias Kienle
- Département des neurosciences fondamentales, Université de Lausanne, Rue du Bugnon 9, CH-1005, Lausanne, Switzerland
| | - Tobias H Kloepper
- Sir William Dunn School of Pathology, Research Group Cell Biology of Intercellular Signaling, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
| | - Dirk Fasshauer
- Département des neurosciences fondamentales, Université de Lausanne, Rue du Bugnon 9, CH-1005, Lausanne, Switzerland.
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50
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Biasutto L, Azzolini M, Szabò I, Zoratti M. The mitochondrial permeability transition pore in AD 2016: An update. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1863:2515-30. [PMID: 26902508 DOI: 10.1016/j.bbamcr.2016.02.012] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 02/04/2016] [Accepted: 02/05/2016] [Indexed: 12/13/2022]
Abstract
Over the past 30years the mitochondrial permeability transition - the permeabilization of the inner mitochondrial membrane due to the opening of a wide pore - has progressed from being considered a curious artifact induced in isolated mitochondria by Ca(2+) and phosphate to a key cell-death-inducing process in several major pathologies. Its relevance is by now universally acknowledged and a pharmacology targeting the phenomenon is being developed. The molecular nature of the pore remains to this day uncertain, but progress has recently been made with the identification of the FOF1 ATP synthase as the probable proteic substrate. Researchers sharing this conviction are however divided into two camps: these believing that only the ATP synthase dimers or oligomers can form the pore, presumably in the contact region between monomers, and those who consider that the ring-forming c subunits in the FO sector actually constitute the walls of the pore. The latest development is the emergence of a new candidate: Spastic Paraplegia 7 (SPG7), a mitochondrial AAA-type membrane protease which forms a 6-stave barrel. This review summarizes recent developments of research on the pathophysiological relevance and on the molecular nature of the mitochondrial permeability transition pore. This article is part of a Special Issue entitled: Mitochondrial Channels edited by Pierre Sonveaux, Pierre Maechler and Jean-Claude Martinou.
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Affiliation(s)
- Lucia Biasutto
- CNR Neuroscience Institute, Viale G. Colombo 3, 35121 Padova, Italy; University of Padova, Department of Biomedical Sciences, Viale G. Colombo 3, 35121 Padova, Italy
| | - Michele Azzolini
- CNR Neuroscience Institute, Viale G. Colombo 3, 35121 Padova, Italy; University of Padova, Department of Biomedical Sciences, Viale G. Colombo 3, 35121 Padova, Italy
| | - Ildikò Szabò
- CNR Neuroscience Institute, Viale G. Colombo 3, 35121 Padova, Italy; University of Padova, Department of Biology, Viale G. Colombo 3, 35121 Padova, Italy
| | - Mario Zoratti
- CNR Neuroscience Institute, Viale G. Colombo 3, 35121 Padova, Italy; University of Padova, Department of Biomedical Sciences, Viale G. Colombo 3, 35121 Padova, Italy.
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