1
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Yang P, Zhang W, Zeng L, Tao X, Ding K, Wang Z. A novel splice variant in intron 10 of PEX6 is associated with Zellweger Syndrome in a Chinese neonate. Gene 2024:148767. [PMID: 39013483 DOI: 10.1016/j.gene.2024.148767] [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: 02/28/2024] [Revised: 04/20/2024] [Accepted: 07/12/2024] [Indexed: 07/18/2024]
Abstract
BACKGROUND Zellweger Syndrome (ZS), or cerebrohepatorenal syndrome, is a rare disorder due to PEX gene mutations affecting peroxisome function. While PEX6 coding mutations are known to cause ZS, the impact of noncoding mutations is less clear. METHODS A Chinese neonate and his family were subjected to whole exome sequencing (WES) and bioinformatics to assess variant pathogenicity. A minigene assay was also performed for detailed splicing variant analysis. RESULTS WES identified compound heterozygous PEX6 variants: c.315G>A (p. Trp105Ter) and c.2095-3 T>G. Minigene assays indicated that the latter variant led to abnormal mRNA splicing and the loss of exon 11 in PEX6 expression, potentially causing nonsense-mediated mRNA decay (NMD) or truncated protein structure. CONCLUSION The study suggests that PEX6: c.2095-3 T>G might be a genetic contributor to the patient's condition, broadening the known mutation spectrum of PEX6. These insights lay groundwork for potential gene therapy for such variants.
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Affiliation(s)
- Pin Yang
- School of Medicine, Department of Medicine, Wuhan University of Science and Technology, Wuhan 430081, China; Division of Neonatology, Wuhan Children's Hospital (Wuhan Maternal and Child Healthcare Hospital), Tongji Medical College, Huazhong University of Science & Technology, Wuhan 430010, China
| | - Weihong Zhang
- Department of Rehabilitation Medicine, Wuhan Children's Hospital (Wuhan Maternal and Child Healthcare Hospital), Tongji Medical College, Huazhong University of Science & Technology, Wuhan 430010, China
| | - Lingkong Zeng
- Division of Neonatology, Wuhan Children's Hospital (Wuhan Maternal and Child Healthcare Hospital), Tongji Medical College, Huazhong University of Science & Technology, Wuhan 430010, China.
| | - Xuwei Tao
- Division of Neonatology, Wuhan Children's Hospital (Wuhan Maternal and Child Healthcare Hospital), Tongji Medical College, Huazhong University of Science & Technology, Wuhan 430010, China
| | - Kaiwei Ding
- Division of Neonatology, Wuhan Children's Hospital (Wuhan Maternal and Child Healthcare Hospital), Tongji Medical College, Huazhong University of Science & Technology, Wuhan 430010, China
| | - Zuo Wang
- Division of Neonatology, Wuhan Children's Hospital (Wuhan Maternal and Child Healthcare Hospital), Tongji Medical College, Huazhong University of Science & Technology, Wuhan 430010, China
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2
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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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3
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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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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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6
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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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7
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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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8
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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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9
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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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10
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Peroxins in Peroxisomal Receptor Export System Contribute to Development, Stress Response, and Virulence of Insect Pathogenic Fungus Beauveria bassiana. J Fungi (Basel) 2022; 8:jof8060622. [PMID: 35736105 PMCID: PMC9224678 DOI: 10.3390/jof8060622] [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: 05/19/2022] [Revised: 06/02/2022] [Accepted: 06/07/2022] [Indexed: 02/06/2023] Open
Abstract
In filamentous fungi, recycling of receptors responsible for protein targeting to peroxisomes depends on the receptor export system (RES), which consists of peroxins Pex1, Pex6, and Pex26. This study seeks to functionally characterize these peroxins in the entomopathogenic fungus Beauveria bassiana. BbPex1, BbPex6, and BbPex26 are associated with peroxisomes and interact with each other. The loss of these peroxins did not completely abolish the peroxisome biogenesis. Three peroxins were all absolutely required for PTS1 pathway; however, only BbPex6 and BbPex26 were required for protein translocation via PTS2 pathway. Three gene disruption mutants displayed the similar phenotypic defects in assimilation of nutrients (e.g., fatty acid, protein, and chitin), stress response (e.g., oxidative and osmotic stress), and virulence. Notably, all disruptant displayed significantly enhanced sensitivity to linoleic acid, a polyunsaturated fatty acid. This study reinforces the essential roles of the peroxisome in the lifecycle of entomopathogenic fungi and highlights peroxisomal roles in combating the host defense system.
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11
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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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12
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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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13
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Jansen RLM, Santana-Molina C, van den Noort M, Devos DP, van der Klei IJ. Comparative Genomics of Peroxisome Biogenesis Proteins: Making Sense of the PEX Proteins. Front Cell Dev Biol 2021; 9:654163. [PMID: 34095119 PMCID: PMC8172628 DOI: 10.3389/fcell.2021.654163] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 04/21/2021] [Indexed: 11/29/2022] Open
Abstract
PEX genes encode proteins involved in peroxisome biogenesis and proliferation. Using a comparative genomics approach, we clarify the evolutionary relationships between the 37 known PEX proteins in a representative set of eukaryotes, including all common model organisms, pathogenic unicellular eukaryotes and human. A large number of previously unknown PEX orthologs were identified. We analyzed all PEX proteins, their conservation and domain architecture and defined the core set of PEX proteins that is required to make a peroxisome. The molecular processes in peroxisome biogenesis in different organisms were put into context, showing that peroxisomes are not static organelles in eukaryotic evolution. Organisms that lack peroxisomes still contain a few PEX proteins, which probably play a role in alternative processes. Finally, the relationships between PEX proteins of two large families, the Pex11 and Pex23 families, were analyzed, thereby contributing to the understanding of their complicated and sometimes incorrect nomenclature. We provide an exhaustive overview of this important eukaryotic organelle.
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Affiliation(s)
- Renate L M Jansen
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
| | - Carlos Santana-Molina
- Centro Andaluz de Biología del Desarrollo, Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Seville, Spain
| | - Marco van den Noort
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
| | - Damien P Devos
- Centro Andaluz de Biología del Desarrollo, Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Seville, Spain
| | - Ida J van der Klei
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
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14
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Stehlik T, Kremp M, Kahnt J, Bölker M, Freitag J. Peroxisomal targeting of a protein phosphatase type 2C via mitochondrial transit. Nat Commun 2020; 11:2355. [PMID: 32398688 PMCID: PMC7217942 DOI: 10.1038/s41467-020-16146-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 04/16/2020] [Indexed: 11/16/2022] Open
Abstract
Correct intracellular distribution of proteins is critical for the function of eukaryotic cells. Certain proteins are targeted to more than one cellular compartment, e.g. to mitochondria and peroxisomes. The protein phosphatase Ptc5 from Saccharomyces cerevisiae contains an N-terminal mitochondrial presequence followed by a transmembrane domain, and has been detected in the mitochondrial intermembrane space. Here we show mitochondrial transit of Ptc5 to peroxisomes. Translocation of Ptc5 to peroxisomes depended both on the C-terminal peroxisomal targeting signal (PTS1) and N-terminal cleavage by the mitochondrial inner membrane peptidase complex. Indirect targeting of Ptc5 to peroxisomes prevented deleterious effects of its phosphatase activity in the cytosol. Sorting of Ptc5 involves simultaneous interaction with import machineries of both organelles. We identify additional mitochondrial proteins with PTS1, which localize in both organelles and can increase their physical association. Thus, a tug-of-war-like mechanism can influence the interaction and communication of two cellular compartments.
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Affiliation(s)
- Thorsten Stehlik
- Department of Biology, Philipps University Marburg, Marburg, Germany
| | - Marco Kremp
- Department of Biology, Philipps University Marburg, Marburg, Germany
| | - Jörg Kahnt
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Michael Bölker
- Department of Biology, Philipps University Marburg, Marburg, Germany.
- LOEWE Center for Synthetic Microbiology, Marburg, Germany.
| | - Johannes Freitag
- Department of Biology, Philipps University Marburg, Marburg, Germany.
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15
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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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16
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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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17
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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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18
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Su T, Li W, Wang P, Ma C. Dynamics of Peroxisome Homeostasis and Its Role in Stress Response and Signaling in Plants. FRONTIERS IN PLANT SCIENCE 2019; 10:705. [PMID: 31214223 PMCID: PMC6557986 DOI: 10.3389/fpls.2019.00705] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Accepted: 05/13/2019] [Indexed: 05/19/2023]
Abstract
Peroxisomes play vital roles in plant growth, development, and environmental stress response. During plant development and in response to environmental stresses, the number and morphology of peroxisomes are dynamically regulated to maintain peroxisome homeostasis in cells. To execute their various functions in the cell, peroxisomes associate and communicate with other organelles. Under stress conditions, reactive oxygen species (ROS) produced in peroxisomes and other organelles activate signal transduction pathways, in a process known as retrograde signaling, to synergistically regulate defense systems. In this review, we focus on the recent advances in the plant peroxisome field to provide an overview of peroxisome biogenesis, degradation, crosstalk with other organelles, and their role in response to environmental stresses.
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19
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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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20
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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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21
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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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22
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Thomas AS, Krikken AM, de Boer R, Williams C. Hansenula polymorpha Aat2p is targeted to peroxisomes via a novel Pex20p-dependent pathway. FEBS Lett 2018; 592:2466-2475. [PMID: 29924881 PMCID: PMC6099311 DOI: 10.1002/1873-3468.13168] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 05/25/2018] [Accepted: 06/11/2018] [Indexed: 12/29/2022]
Abstract
Saccharomyces cerevisiae Aat2p contains a peroxisomal targeting signal type‐1 and localizes to peroxisomes in oleate‐grown cells, but not in glucose‐grown cells. Here, we have investigated Aat2p from the yeast Hansenula polymorpha, which lacks a recognizable peroxisomal targeting signal. Aat2p tagged with GFP at its C terminus displays a dual cytosol‐peroxisome localization in ethanol‐grown cells. The partial peroxisomal localization of Aat2p persisted in the absence of the classical cycling receptors Pex5p and Pex7p but Aat2p targeting to peroxisomes was reduced in cells deleted for the matrix protein import factors PEX1, PEX2 and PEX13. Furthermore, we demonstrate that Aat2p targeting to peroxisomes requires Pex20p. Together, our data identify a Pex20p‐dependent pathway for targeting Aat2p to peroxisomes.
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Affiliation(s)
- Ann S Thomas
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
| | - Arjen M Krikken
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
| | - Rinse de Boer
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
| | - Chris Williams
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
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23
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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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24
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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: 72] [Impact Index Per Article: 12.0] [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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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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26
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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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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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28
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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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29
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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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30
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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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31
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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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32
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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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33
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Sysoeva TA. Assessing heterogeneity in oligomeric AAA+ machines. Cell Mol Life Sci 2017; 74:1001-1018. [PMID: 27669691 PMCID: PMC11107579 DOI: 10.1007/s00018-016-2374-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 09/13/2016] [Accepted: 09/19/2016] [Indexed: 10/20/2022]
Abstract
ATPases Associated with various cellular Activities (AAA+ ATPases) are molecular motors that use the energy of ATP binding and hydrolysis to remodel their target macromolecules. The majority of these ATPases form ring-shaped hexamers in which the active sites are located at the interfaces between neighboring subunits. Structural changes initiate in an active site and propagate to distant motor parts that interface and reshape the target macromolecules, thereby performing mechanical work. During the functioning cycle, the AAA+ motor transits through multiple distinct states. Ring architecture and placement of the catalytic sites at the intersubunit interfaces allow for a unique level of coordination among subunits of the motor. This in turn results in conformational differences among subunits and overall asymmetry of the motor ring as it functions. To date, a large amount of structural information has been gathered for different AAA+ motors, but even for the most characterized of them only a few structural states are known and the full mechanistic cycle cannot be yet reconstructed. Therefore, the first part of this work will provide a broad overview of what arrangements of AAA+ subunits have been structurally observed focusing on diversity of ATPase oligomeric ensembles and heterogeneity within the ensembles. The second part of this review will concentrate on methods that assess structural and functional heterogeneity among subunits of AAA+ motors, thus bringing us closer to understanding the mechanism of these fascinating molecular motors.
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Affiliation(s)
- Tatyana A Sysoeva
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA.
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34
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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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36
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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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37
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Na H, Song G. Predicting the functional motions of p97 using symmetric normal modes. Proteins 2016; 84:1823-1835. [PMID: 27653958 DOI: 10.1002/prot.25164] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 09/09/2016] [Accepted: 09/15/2016] [Indexed: 01/01/2023]
Abstract
p97 is a protein complex of the AAA+ family. Although functions of p97 are well understood, the mechanism by which p97 performs its unfolding activities remains unclear. In this work, we present a novel way of applying normal mode analysis to study this six-fold symmetric molecular machine. By selecting normal modes that are axial symmetric and give the largest movements at D1 or D2 pore residues, we are able to predict the functional motions of p97, which are then validated by experimentally observed conformational changes. Our results shed light and provide new understandings on several key steps of the p97 functional process that were previously unclear or controversial, and thus are able to reconcile multiple previous findings. Specifically, our results reveal that (i) a venous valve-like mechanism is used at D2 pore to ensure a one-way exit-only traffic of substrates; (ii) D1 pore remains shut during the functional process; (iii) the "swing-up" motion of the N domain is closely coupled with the vertical motion of the D1 pore along the pore axis; (iv) because of the shut D1 pore and the one-way traffic at D2 pore, it is highly likely that substrates enter the chamber through the gaps at the D1/D2 interface. The limited chamber volume inside p97 suggests that a substrate may be pulling out from D2 while at the same time being pulling in at the interface; (v) lastly, p97 uses a series of actions that alternate between twisting and pulling to remove the substrate. Proteins 2016; 84:1823-1835. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Hyuntae Na
- Department of Computer Science, Penn State Harrisburg, Middletown, Pennsylvania, 17057
| | - Guang Song
- Department of Computer Science, Iowa State University, Ames, Iowa, 50011.,Program of Bioinformatics and Computational Biology, Iowa State University, Ames, Iowa, 50011.,L. H. Baker Center for Bioinformatics and Biological Statistics Iowa State University, Ames, Iowa, 50011
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Smith CEL, Poulter JA, Levin AV, Capasso JE, Price S, Ben-Yosef T, Sharony R, Newman WG, Shore RC, Brookes SJ, Mighell AJ, Inglehearn CF. Spectrum of PEX1 and PEX6 variants in Heimler syndrome. Eur J Hum Genet 2016; 24:1565-1571. [PMID: 27302843 PMCID: PMC5026821 DOI: 10.1038/ejhg.2016.62] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 04/12/2016] [Accepted: 04/27/2016] [Indexed: 12/30/2022] Open
Abstract
Heimler syndrome (HS) consists of recessively inherited sensorineural hearing loss, amelogenesis imperfecta (AI) and nail abnormalities, with or without visual defects. Recently HS was shown to result from hypomorphic mutations in PEX1 or PEX6, both previously implicated in Zellweger Syndrome Spectrum Disorders (ZSSD). ZSSD are a group of conditions consisting of craniofacial and neurological abnormalities, sensory defects and multi-organ dysfunction. The finding of HS-causing mutations in PEX1 and PEX6 shows that HS represents the mild end of the ZSSD spectrum, though these conditions were previously thought to be distinct nosological entities. Here, we present six further HS families, five with PEX6 variants and one with PEX1 variants, and show the patterns of Pex1, Pex14 and Pex6 immunoreactivity in the mouse retina. While Ratbi et al. found more HS-causing mutations in PEX1 than in PEX6, as is the case for ZSSD, in this cohort PEX6 variants predominate, suggesting both genes play a significant role in HS. The PEX6 variant c.1802G>A, p.(R601Q), reported previously in compound heterozygous state in one HS and three ZSSD cases, was found in compound heterozygous state in three HS families. Haplotype analysis suggests a common founder variant. All families segregated at least one missense variant, consistent with the hypothesis that HS results from genotypes including milder hypomorphic alleles. The clinical overlap of HS with the more common Usher syndrome and lack of peroxisomal abnormalities on plasma screening suggest that HS may be under-diagnosed. Recognition of AI is key to the accurate diagnosis of HS.
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Affiliation(s)
- Claire E L Smith
- Leeds Institute of Biomedical and Clinical Sciences, St. James's University Hospital, University of Leeds, Leeds, UK
| | - James A Poulter
- Leeds Institute of Biomedical and Clinical Sciences, St. James's University Hospital, University of Leeds, Leeds, UK
| | - Alex V Levin
- Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA, USA.,Children's Hospital of the King's Daughters, Norfolk, VA, USA.,Pediatric Ophthalmology and Ocular Genetics, Philadelphia, PA, USA
| | - Jenina E Capasso
- Pediatric Ophthalmology and Ocular Genetics, Philadelphia, PA, USA
| | - Susan Price
- Department of Clinical Genetics, Northampton General Hospital, NHS Trust, Northampton, UK
| | | | - Reuven Sharony
- The Genetic Institute and Obstetrics and Gynaecology Department, Meir Medical Center, Kfar Saba, Israel
| | - William G Newman
- Manchester Centre for Genomic Medicine, St. Mary's Hospital, Manchester Academic Health Sciences Centre, Manchester, UK.,Manchester Centre for Genomic Medicine, Institute of Human Development, University of Manchester, Manchester, UK
| | - Roger C Shore
- School of Dentistry, Department of Oral Biology, St. James's University Hospital, University of Leeds, Leeds, UK
| | - Steven J Brookes
- School of Dentistry, Department of Oral Biology, St. James's University Hospital, University of Leeds, Leeds, UK
| | - Alan J Mighell
- Leeds Institute of Biomedical and Clinical Sciences, St. James's University Hospital, University of Leeds, Leeds, UK.,Department of Oral Medicine, School of Dentistry, University of Leeds, Leeds, UK
| | - Chris F Inglehearn
- Leeds Institute of Biomedical and Clinical Sciences, St. James's University Hospital, University of Leeds, Leeds, UK
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39
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Peroxisomal protein import pores. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:821-7. [DOI: 10.1016/j.bbamcr.2015.10.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 10/14/2015] [Accepted: 10/16/2015] [Indexed: 02/06/2023]
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40
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Sibirny AA. Yeast peroxisomes: structure, functions and biotechnological opportunities. FEMS Yeast Res 2016; 16:fow038. [DOI: 10.1093/femsyr/fow038] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/07/2016] [Indexed: 01/02/2023] Open
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41
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Nucleotide-dependent assembly of the peroxisomal receptor export complex. Sci Rep 2016; 6:19838. [PMID: 26842748 PMCID: PMC4740771 DOI: 10.1038/srep19838] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 11/30/2015] [Indexed: 01/27/2023] Open
Abstract
Pex1p and Pex6p are two AAA-ATPases required for biogenesis of peroxisomes. Both proteins form a hetero-hexameric complex in an ATP-dependent manner, which has a dual localization in the cytosol and at the peroxisomal membrane. At the peroxisomal membrane, the complex is responsible for the release of the import receptor Pex5p at the end of the matrix protein import cycle. In this study, we analyzed the recruitment of the AAA-complex to its anchor protein Pex15p at the peroxisomal membrane. We show that the AAA-complex is properly assembled even under ADP-conditions and is able to bind efficiently to Pex15p in vivo. We reconstituted binding of the Pex1/6p-complex to Pex15p in vitro and show that Pex6p mediates binding to the cytosolic part of Pex15p via a direct interaction. Analysis of the isolated complex revealed a stoichiometry of Pex1p/Pex6p/Pex15p of 3:3:3, indicating that each Pex6p molecule of the AAA-complex binds Pex15p. Binding of the AAA-complex to Pex15p in particular and to the import machinery in general is stabilized when ATP is bound to the second AAA-domain of Pex6p and its hydrolysis is prevented. The data indicate that receptor release in peroxisomal protein import is associated with a nucleotide-depending Pex1/6p-cycle of Pex15p-binding and release.
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42
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Barthelme D, Sauer RT. Origin and Functional Evolution of the Cdc48/p97/VCP AAA+ Protein Unfolding and Remodeling Machine. J Mol Biol 2015; 428:1861-9. [PMID: 26608813 DOI: 10.1016/j.jmb.2015.11.015] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 11/03/2015] [Accepted: 11/16/2015] [Indexed: 01/25/2023]
Abstract
The AAA+ Cdc48 ATPase (alias p97 or VCP) is a key player in multiple ubiquitin-dependent cell signaling, degradation, and quality control pathways. Central to these broad biological functions is the ability of Cdc48 to interact with a large number of adaptor proteins and to remodel macromolecular proteins and their complexes. Different models have been proposed to explain how Cdc48 might couple ATP hydrolysis to forcible unfolding, dissociation, or remodeling of cellular clients. In this review, we provide an overview of possible mechanisms for substrate unfolding/remodeling by this conserved and essential AAA+ protein machine and their adaption and possible biological function throughout evolution.
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Affiliation(s)
- Dominik Barthelme
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Max Planck Institute for Infection Biology, Berlin 10117, Germany
| | - Robert T Sauer
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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43
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Tan D, Blok NB, Rapoport TA, Walz T. Structures of the double-ring AAA ATPase Pex1-Pex6 involved in peroxisome biogenesis. FEBS J 2015; 283:986-92. [PMID: 26476099 DOI: 10.1111/febs.13569] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 10/12/2015] [Accepted: 10/15/2015] [Indexed: 11/27/2022]
Abstract
The Pex1 and Pex6 proteins are members of the AAA family of ATPases and are involved in peroxisome biogenesis. Recently, cryo-electron microscopy structures of the Pex1-Pex6 complex in different nucleotide states have been determined. This Structural Snapshot describes the structural features of the complex and their implications for its function, as well as questions that still await answers.
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Affiliation(s)
- Dongyan Tan
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Neil B Blok
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA.,Department of Cell Biology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA
| | - Tom A Rapoport
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA.,Department of Cell Biology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA
| | - Thomas Walz
- The Rockefeller University, New York, NY, USA
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44
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Recent Advances in Deciphering the Structure and Molecular Mechanism of the AAA+ ATPase N-Ethylmaleimide-Sensitive Factor (NSF). J Mol Biol 2015; 428:1912-26. [PMID: 26546278 DOI: 10.1016/j.jmb.2015.10.026] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 10/24/2015] [Accepted: 10/27/2015] [Indexed: 12/16/2022]
Abstract
N-ethylmaleimide-sensitive factor (NSF), first discovered in 1988, is a key factor for eukaryotic trafficking, including protein and hormone secretion and neurotransmitter release. It is a member of the AAA+ family (ATPases associated with diverse cellular activities). NSF disassembles soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complexes in conjunction with soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP). Structural studies of NSF and its complex with SNAREs and SNAPs (known as 20S supercomplex) started about 20years ago. Crystal structures of individual N and D2 domains of NSF and low-resolution electron microscopy structures of full-length NSF and 20S supercomplex have been reported over the years. Nevertheless, the molecular architecture of the 20S supercomplex and the molecular mechanism of NSF-mediated SNARE complex disassembly remained unclear until recently. Here we review recent atomic-resolution or near-atomic resolution structures of NSF and of the 20S supercomplex, as well as recent insights into the molecular mechanism and energy requirements of NSF. We also compare NSF with other known AAA+ family members.
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45
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Grimm I, Erdmann R, Girzalsky W. Role of AAA(+)-proteins in peroxisome biogenesis and function. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1863:828-37. [PMID: 26453804 DOI: 10.1016/j.bbamcr.2015.10.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 09/30/2015] [Accepted: 10/03/2015] [Indexed: 11/16/2022]
Abstract
Mutations in the PEX1 gene, which encodes a protein required for peroxisome biogenesis, are the most common cause of the Zellweger spectrum diseases. The recognition that Pex1p shares a conserved ATP-binding domain with p97 and NSF led to the discovery of the extended family of AAA+-type ATPases. So far, four AAA+-type ATPases are related to peroxisome function. Pex6p functions together with Pex1p in peroxisome biogenesis, ATAD1/Msp1p plays a role in membrane protein targeting and a member of the Lon-family of proteases is associated with peroxisomal quality control. This review summarizes the current knowledge on the AAA+-proteins involved in peroxisome biogenesis and function.
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Affiliation(s)
- Immanuel Grimm
- Abteilung für Systembiochemie, Medizinische Fakultät der Ruhr-Universität Bochum, D-44780 Bochum, Germany
| | - Ralf Erdmann
- Abteilung für Systembiochemie, Medizinische Fakultät der Ruhr-Universität Bochum, D-44780 Bochum, Germany.
| | - Wolfgang Girzalsky
- Abteilung für Systembiochemie, Medizinische Fakultät der Ruhr-Universität Bochum, D-44780 Bochum, Germany.
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46
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Platta HW, Brinkmeier R, Reidick C, Galiani S, Clausen MP, Eggeling C. Regulation of peroxisomal matrix protein import by ubiquitination. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1863:838-49. [PMID: 26367801 DOI: 10.1016/j.bbamcr.2015.09.010] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 09/09/2015] [Accepted: 09/10/2015] [Indexed: 02/02/2023]
Abstract
Peroxisomes are organelles that play an important role in many cellular tasks. The functionality of peroxisomes depends on the proper import of their matrix proteins. Peroxisomal matrix proteins are imported posttranslationally in a folded, sometimes even oligomeric state. They harbor a peroxisomal targeting sequence (PTS), which is recognized by dynamic PTS-receptors in the cytosol. The PTS-receptors ferry the cargo to the peroxisomal membrane, where they become part of a transient import pore and then release the cargo into the peroxisomal lumen. Subsequentially, the PTS-receptors are ubiquitinated in order to mark them for the export-machinery, which releases them back to the cytosol. Upon deubiquitination, the PTS-receptors can facilitate further rounds of cargo import. Because the ubiquitination of the receptors is an essential step in the import cycle, it also represents a central regulatory element that governs peroxisomal dynamics. In this review we want to give an introduction to the functional role played by ubiquitination during peroxisomal protein import and highlight the mechanistic concepts that have emerged based on data derived from different species since the discovery of the first ubiquitinated peroxin 15years ago. Moreover, we discuss future tasks and the potential of using advanced technologies for investigating further details of peroxisomal protein transport.
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Affiliation(s)
- Harald W Platta
- Biochemie Intrazellulärer Transportprozesse, Ruhr-Universität Bochum, 44780 Bochum, Germany.
| | - Rebecca Brinkmeier
- Biochemie Intrazellulärer Transportprozesse, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Christina Reidick
- Biochemie Intrazellulärer Transportprozesse, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Silvia Galiani
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford OX3 9DS, United Kingdom
| | - Mathias P Clausen
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford OX3 9DS, United Kingdom
| | - Christian Eggeling
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford OX3 9DS, United Kingdom.
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47
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Yuan W, Veenhuis M, van der Klei IJ. The birth of yeast peroxisomes. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1863:902-10. [PMID: 26367802 DOI: 10.1016/j.bbamcr.2015.09.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Revised: 09/08/2015] [Accepted: 09/09/2015] [Indexed: 11/25/2022]
Abstract
This contribution describes the phenotypic differences of yeast peroxisome-deficient mutants (pex mutants). In some cases different phenotypes were reported for yeast mutants deleted in the same PEX gene. These differences are most likely related to the marker proteins and methods used to detect peroxisomal remnants. This is especially evident for pex3 and pex19 mutants, where the localization of receptor docking proteins (Pex13, Pex14) resulted in the identification of peroxisomal membrane remnants, which do not contain other peroxisomal membrane proteins, such as the ring proteins Pex2, Pex10 and Pex12. These structures in pex3 and pex19 cells are the template for peroxisome formation upon introduction of the missing gene. Taken together, these data suggest that in all yeast pex mutants analyzed so far peroxisomes are not formed de novo but use membrane remnant structures as a template for peroxisome formation upon reintroduction of the missing gene. The relevance of this model for peroxisomal membrane protein and lipid sorting to peroxisomes is discussed.
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Affiliation(s)
- Wei Yuan
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, the Netherlands
| | - Marten Veenhuis
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, the Netherlands
| | - Ida J van der Klei
- Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, the Netherlands.
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48
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Unique double-ring structure of the peroxisomal Pex1/Pex6 ATPase complex revealed by cryo-electron microscopy. Proc Natl Acad Sci U S A 2015; 112:E4017-25. [PMID: 26170309 DOI: 10.1073/pnas.1500257112] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Members of the AAA family of ATPases assemble into hexameric double rings and perform vital functions, yet their molecular mechanisms remain poorly understood. Here, we report structures of the Pex1/Pex6 complex; mutations in these proteins frequently cause peroxisomal diseases. The structures were determined in the presence of different nucleotides by cryo-electron microscopy. Models were generated using a computational approach that combines Monte Carlo placement of structurally homologous domains into density maps with energy minimization and refinement protocols. Pex1 and Pex6 alternate in an unprecedented hexameric double ring. Each protein has two N-terminal domains, N1 and N2, structurally related to the single N domains in p97 and N-ethylmaleimide sensitive factor (NSF); N1 of Pex1 is mobile, but the others are packed against the double ring. The N-terminal ATPase domains are inactive, forming a symmetric D1 ring, whereas the C-terminal domains are active, likely in different nucleotide states, and form an asymmetric D2 ring. These results suggest how subunit activity is coordinated and indicate striking similarities between Pex1/Pex6 and p97, supporting the hypothesis that the Pex1/Pex6 complex has a role in peroxisomal protein import analogous to p97 in ER-associated protein degradation.
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49
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Ciniawsky S, Grimm I, Saffian D, Girzalsky W, Erdmann R, Wendler P. Molecular snapshots of the Pex1/6 AAA+ complex in action. Nat Commun 2015; 6:7331. [PMID: 26066397 PMCID: PMC4490564 DOI: 10.1038/ncomms8331] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 04/28/2015] [Indexed: 01/23/2023] Open
Abstract
The peroxisomal proteins Pex1 and Pex6 form a heterohexameric type II AAA+ ATPase complex, which fuels essential protein transport across peroxisomal membranes. Mutations in either ATPase in humans can lead to severe peroxisomal disorders and early death. We present an extensive structural and biochemical analysis of the yeast Pex1/6 complex. The heterohexamer forms a trimer of Pex1/6 dimers with a triangular geometry that is atypical for AAA+ complexes. While the C-terminal nucleotide-binding domains (D2) of Pex6 constitute the main ATPase activity of the complex, both D2 harbour essential substrate-binding motifs. ATP hydrolysis results in a pumping motion of the complex, suggesting that Pex1/6 function involves substrate translocation through its central channel. Mutation of the Walker B motif in one D2 domain leads to ATP hydrolysis in the neighbouring domain, giving structural insights into inter-domain communication of these unique heterohexameric AAA+ assemblies. Pex1 and Pex6 form a heterohexameric AAA+ ATPase complex with triangular geometry at the peroxisome membrane. Here the authors use electron microscopy to show that the complex undergoes conformational changes upon ATP hydrolysis, and demonstrate inter-domain communication between neighbouring nucleotide-binding domains.
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Affiliation(s)
- Susanne Ciniawsky
- Gene Center Munich, Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, Munich 81377, Germany
| | - Immanuel Grimm
- Institute of Biochemistry and Pathobiochemistry, Department of Systems Biochemistry, Faculty of Medicine, Ruhr-Universität Bochum, Bochum 44801, Germany
| | - Delia Saffian
- Institute of Biochemistry and Pathobiochemistry, Department of Systems Biochemistry, Faculty of Medicine, Ruhr-Universität Bochum, Bochum 44801, Germany
| | - Wolfgang Girzalsky
- Institute of Biochemistry and Pathobiochemistry, Department of Systems Biochemistry, Faculty of Medicine, Ruhr-Universität Bochum, Bochum 44801, Germany
| | - Ralf Erdmann
- Institute of Biochemistry and Pathobiochemistry, Department of Systems Biochemistry, Faculty of Medicine, Ruhr-Universität Bochum, Bochum 44801, Germany
| | - Petra Wendler
- Gene Center Munich, Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, Munich 81377, Germany
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