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Muhammad D, Smith KA, Bartel B. Plant peroxisome proteostasis-establishing, renovating, and dismantling the peroxisomal proteome. Essays Biochem 2022; 66:229-242. [PMID: 35538741 PMCID: PMC9375579 DOI: 10.1042/ebc20210059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 04/26/2022] [Accepted: 04/27/2022] [Indexed: 12/28/2022]
Abstract
Plant peroxisomes host critical metabolic reactions and insulate the rest of the cell from reactive byproducts. The specialization of peroxisomal reactions is rooted in how the organelle modulates its proteome to be suitable for the tissue, environment, and developmental stage of the organism. The story of plant peroxisomal proteostasis begins with transcriptional regulation of peroxisomal protein genes and the synthesis, trafficking, import, and folding of peroxisomal proteins. The saga continues with assembly and disaggregation by chaperones and degradation via proteases or the proteasome. The story concludes with organelle recycling via autophagy. Some of these processes as well as the proteins that facilitate them are peroxisome-specific, while others are shared among organelles. Our understanding of translational regulation of plant peroxisomal protein transcripts and proteins necessary for pexophagy remain based in findings from other models. Recent strides to elucidate transcriptional control, membrane dynamics, protein trafficking, and conditions that induce peroxisome turnover have expanded our knowledge of plant peroxisomal proteostasis. Here we review our current understanding of the processes and proteins necessary for plant peroxisome proteostasis-the emergence, maintenance, and clearance of the peroxisomal proteome.
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Affiliation(s)
| | - Kathryn A Smith
- Department of BioSciences, Rice University, Houston, TX 77005, U.S.A
| | - Bonnie Bartel
- Department of BioSciences, Rice University, Houston, TX 77005, U.S.A
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2
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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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3
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Mano S, Hayashi Y, Hikino K, Otomo M, Kanai M, Nishimura M. Ubiquitin-conjugating activity by PEX4 is required for efficient protein transport to peroxisomes in Arabidopsis thaliana. J Biol Chem 2022; 298:102038. [PMID: 35595097 PMCID: PMC9190015 DOI: 10.1016/j.jbc.2022.102038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 05/10/2022] [Accepted: 05/11/2022] [Indexed: 11/08/2022] Open
Abstract
Protein transport to peroxisomes requires various proteins, such as receptors in the cytosol and components of the transport machinery on peroxisomal membranes. The Arabidopsis apem (aberrant peroxisome morphology) mutant apem7 shows decreased efficiency of peroxisome targeting signal 1–dependent protein transport to peroxisomes. In apem7 mutants, peroxisome targeting signal 2–dependent protein transport is also disturbed, and plant growth is repressed. The APEM7 gene encodes a protein homologous to peroxin 4 (PEX4), which belongs to the ubiquitin-conjugating (UBC) protein family; however, the UBC activity of Arabidopsis PEX4 remains to be investigated. Here, we show using electron microscopy and immunoblot analysis using specific PEX4 antibodies and in vitro transcription/translation assay that PEX4 localizes to peroxisomal membranes and possesses UBC activity. We found that the substitution of proline with leucine by apem7 mutation alters ubiquitination of PEX4. Furthermore, substitution of the active-site cysteine residue at position 90 in PEX4, which was predicted to be a ubiquitin-conjugation site, with alanine did not restore the apem7 phenotype. Taken together, these findings indicate that abnormal ubiquitination in the apem7 mutant alters ubiquitin signaling during the process of protein transport, suggesting that the UBC activity of PEX4 is indispensable for efficient protein transport to peroxisomes.
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Affiliation(s)
- Shoji Mano
- Department of Cell Biology, National Institute for Basic Biology, Myodaiji, Okazaki, Japan; Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Myodaiji, Okazaki, Japan.
| | - Yasuko Hayashi
- Graduate School of Science and Technology, Niigata University, Ikarashi, Niigata, Japan
| | - Kazumi Hikino
- Department of Cell Biology, National Institute for Basic Biology, Myodaiji, Okazaki, Japan
| | - Masayoshi Otomo
- Graduate School of Science and Technology, Niigata University, Ikarashi, Niigata, Japan
| | - Masatake Kanai
- Department of Cell Biology, National Institute for Basic Biology, Myodaiji, Okazaki, Japan
| | - Mikio Nishimura
- Department of Cell Biology, National Institute for Basic Biology, Myodaiji, Okazaki, Japan
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4
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Traver MS, Bradford SE, Olmos JL, Wright ZJ, Miller MD, Xu W, Phillips GN, Bartel B. The Structure of the Arabidopsis PEX4-PEX22 Peroxin Complex-Insights Into Ubiquitination at the Peroxisomal Membrane. Front Cell Dev Biol 2022; 10:838923. [PMID: 35300425 PMCID: PMC8922245 DOI: 10.3389/fcell.2022.838923] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Accepted: 01/28/2022] [Indexed: 01/11/2023] Open
Abstract
Peroxisomes are eukaryotic organelles that sequester critical oxidative reactions and process the resulting reactive oxygen species into less toxic byproducts. Peroxisome function and formation are coordinated by peroxins (PEX proteins) that guide peroxisome biogenesis and division and shuttle proteins into the lumen and membrane of the organelle. Despite the importance of peroxins in plant metabolism and development, no plant peroxin structures have been reported. Here we report the X-ray crystal structure of the PEX4-PEX22 peroxin complex from the reference plant Arabidopsis thaliana. PEX4 is a ubiquitin-conjugating enzyme (UBC) that ubiquitinates proteins associated with the peroxisomal membrane, and PEX22 is a peroxisomal membrane protein that anchors PEX4 to the peroxisome and facilitates PEX4 activity. We co-expressed Arabidopsis PEX4 as a translational fusion with the soluble PEX4-interacting domain of PEX22 in E. coli. The fusion was linked via a protease recognition site, allowing us to separate PEX4 and PEX22 following purification and solve the structure of the complex. We compared the structure of the PEX4-PEX22 complex to the previously published structures of yeast orthologs. Arabidopsis PEX4 displays the typical UBC structure expected from its sequence. Although Arabidopsis PEX22 lacks notable sequence identity to yeast PEX22, it maintains a similar Rossmann fold-like structure. Several salt bridges are positioned to contribute to the specificity of PEX22 for PEX4 versus other Arabidopsis UBCs, and the long unstructured PEX22 tether would allow PEX4-mediated ubiquitination of distant peroxisomal membrane targets without dissociation from PEX22. The Arabidopsis PEX4-PEX22 structure also revealed that the residue altered in pex4-1 (P123L), a mutant previously isolated via a forward-genetic screen for peroxisomal dysfunction, is near the active site cysteine of PEX4. We demonstrated in vitro UBC activity for the PEX4-PEX22 complex and found that the pex4-1 enzyme has reduced in vitro ubiquitin-conjugating activity and altered specificity compared to PEX4. Our findings illuminate the role of PEX4 and PEX22 in peroxisome structure and function and provide tools for future exploration of ubiquitination at the peroxisome surface.
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Affiliation(s)
- Melissa S. Traver
- Department of Biosciences, Rice University, Houston, TX, United States
| | - Sarah E. Bradford
- Department of Biosciences, Rice University, Houston, TX, United States
| | - Jose Luis Olmos
- Department of Biosciences, Rice University, Houston, TX, United States
| | - Zachary J. Wright
- Department of Biosciences, Rice University, Houston, TX, United States
| | | | - Weijun Xu
- Department of Biosciences, Rice University, Houston, TX, United States
| | - George N. Phillips
- Department of Biosciences, Rice University, Houston, TX, United States
- Department of Chemistry, Rice University, Houston, TX, United States
| | - Bonnie Bartel
- Department of Biosciences, Rice University, Houston, TX, United States
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Chen Z, Ai F, Zhang J, Ma X, Yang W, Wang W, Su Y, Wang M, Yang Y, Mao K, Wang Q, Lascoux M, Liu J, Ma T. Survival in the Tropics despite isolation, inbreeding and asexual reproduction: insights from the genome of the world's southernmost poplar (Populus ilicifolia). THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 103:430-442. [PMID: 32168389 DOI: 10.1111/tpj.14744] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 02/04/2020] [Accepted: 03/02/2020] [Indexed: 05/16/2023]
Abstract
Species are becoming extinct at unprecedented rates as a consequence of human activity. Hence it is important to understand the evolutionary dynamics of species with already small population sizes. Populus ilicifolia is a vulnerable poplar species that is isolated from other poplar species and is uniquely adapted to the Tropics. It has a very limited size, reproduces partly clonally and is therefore an excellent case study for conservation genomics. We present here the first annotated draft genome of P. ilicifolia, characterize genome-wide patterns of polymorphisms and compare those to other poplar species with larger natural ranges. P. ilicifolia experienced a more prolonged and severe decline of effective population size (Ne ) and signs of genetic erosion than any other poplar species with which it was compared. At present, the species has the lowest genome-wide genetic diversity, the highest abundance of long runs of homozygosity, high inbreeding levels as well as a high overall accumulation of deleterious variants. However, more effective purging of severely deleterious variants and adaptation to the Tropics may have contributed to its survival. Hence, in spite of its limited genetic variation, it is certainly worth pursuing the conservation efforts of this unique species.
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Affiliation(s)
- Zeyuan Chen
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
| | - Fandi Ai
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
| | - Junlin Zhang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
| | - Xinzhi Ma
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
| | - Wenlu Yang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
| | - Weiwei Wang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
| | - Yutao Su
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
| | - Mingcheng Wang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
| | - Yongzhi Yang
- State Key Laboratory of Grassland Agro-Ecosystem, Institute of Innovation Ecology & College of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Kangshan Mao
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
| | - Qingfeng Wang
- Key Laboratory of Aquatic Botany and Watershed Ecology, The Chinese Academy of Sciences, Wuhan, 430074, Hubei, China
| | - Martin Lascoux
- Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen, 18D 75326, Uppsala, Sweden
| | - Jianquan Liu
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
- State Key Laboratory of Grassland Agro-Ecosystem, Institute of Innovation Ecology & College of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Tao Ma
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
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Ouyang M, Li X, Zhang J, Feng P, Pu H, Kong L, Bai Z, Rong L, Xu X, Chi W, Wang Q, Chen F, Lu C, Shen J, Zhang L. Liquid-Liquid Phase Transition Drives Intra-chloroplast Cargo Sorting. Cell 2020; 180:1144-1159.e20. [PMID: 32169217 DOI: 10.1016/j.cell.2020.02.045] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 01/14/2020] [Accepted: 02/20/2020] [Indexed: 12/21/2022]
Abstract
In eukaryotic cells, organelle biogenesis is pivotal for cellular function and cell survival. Chloroplasts are unique organelles with a complex internal membrane network. The mechanisms of the migration of imported nuclear-encoded chloroplast proteins across the crowded stroma to thylakoid membranes are less understood. Here, we identified two Arabidopsis ankyrin-repeat proteins, STT1 and STT2, that specifically mediate sorting of chloroplast twin arginine translocation (cpTat) pathway proteins to thylakoid membranes. STT1 and STT2 form a unique hetero-dimer through interaction of their C-terminal ankyrin domains. Binding of cpTat substrate by N-terminal intrinsically disordered regions of STT complex induces liquid-liquid phase separation. The multivalent nature of STT oligomer is critical for phase separation. STT-Hcf106 interactions reverse phase separation and facilitate cargo targeting and translocation across thylakoid membranes. Thus, the formation of phase-separated droplets emerges as a novel mechanism of intra-chloroplast cargo sorting. Our findings highlight a conserved mechanism of phase separation in regulating organelle biogenesis.
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Affiliation(s)
- Min Ouyang
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan 430062, China
| | - Xiaoyi Li
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Jing Zhang
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing, China
| | - Peiqiang Feng
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Hua Pu
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Lingxi Kong
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing, China
| | - Zechen Bai
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing, China
| | - Liwei Rong
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing, China
| | - Xiumei Xu
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, 85 Minglun Street, Kaifeng 475001, China
| | - Wei Chi
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing, China
| | - Qiang Wang
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, 85 Minglun Street, Kaifeng 475001, China
| | - Fan Chen
- State Key Laboratory of Molecular Developmental Biology, Chinese Academy of Sciences, Beijing 100086, China
| | - Congming Lu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Jianren Shen
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Lixin Zhang
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, 85 Minglun Street, Kaifeng 475001, China.
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7
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Pan R, Liu J, Wang S, Hu J. Peroxisomes: versatile organelles with diverse roles in plants. THE NEW PHYTOLOGIST 2020; 225:1410-1427. [PMID: 31442305 DOI: 10.1111/nph.16134] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 08/08/2019] [Indexed: 05/18/2023]
Abstract
Peroxisomes are small, ubiquitous organelles that are delimited by a single membrane and lack genetic material. However, these simple-structured organelles are highly versatile in morphology, abundance and protein content in response to various developmental and environmental cues. In plants, peroxisomes are essential for growth and development and perform diverse metabolic functions, many of which are carried out coordinately by peroxisomes and other organelles physically interacting with peroxisomes. Recent studies have added greatly to our knowledge of peroxisomes, addressing areas such as the diverse proteome, regulation of division and protein import, pexophagy, matrix protein degradation, solute transport, signaling, redox homeostasis and various metabolic and physiological functions. This review summarizes our current understanding of plant peroxisomes, focusing on recent discoveries. Current problems and future efforts required to better understand these organelles are also discussed. An improved understanding of peroxisomes will be important not only to the understanding of eukaryotic cell biology and metabolism, but also to agricultural efforts aimed at improving crop performance and defense.
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Affiliation(s)
- Ronghui Pan
- Seed Science Center, Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Jun Liu
- Seed Science Center, Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Saisai Wang
- Seed Science Center, Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Jianping Hu
- MSU-Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
- Plant Biology Department, Michigan State University, East Lansing, MI, 48824, USA
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8
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Gao FJ, Hu FY, Xu P, Qi YH, Li JK, Zhang YJ, Chen F, Chang Q, Song F, Shen SM, Xu GZ, Wu JH. Expanding the clinical and genetic spectrum of Heimler syndrome. Orphanet J Rare Dis 2019; 14:290. [PMID: 31831025 PMCID: PMC6909578 DOI: 10.1186/s13023-019-1243-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 10/29/2019] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Heimler syndrome (HS) is a rare hereditary systemic disorder, partial clinically overlapping with Usher syndrome. So far, our knowledge of HS is very limited, many cases are misdiagnosed or may not even be diagnosed at all. This study aimed to analyze the clinical and genetic characteristics of HS, and to evaluate potential phenotype-genotype correlations. RESULTS Two HS cases caused by PEX1 mutations were identified, and a novel likely pathogenic mutation, PEX1 c.895_896insTATA, was found. The main ophthalmic finding of the two patients was consistent with retinitis pigmentosa accompanied by cystoid macular edema, but short axial length and hyperopia were also observed as two previously unreported ocular phenotypes. Analysis of the literature showed that of the 29 HS patients previously reported, 12 had PEX6 mutations, 10 had PEX1 mutations, two had PEX26 mutations, and the remaining patients were not genetically tested. Three novel genotype-phenotype correlations were revealed from analysis of these patients. First, most genotypes of every HS patient include at least one missense variant; second, at least one mutation in PEX1 or PEX6 gene affects the AAA-ATPase region in every HS patient with retinal dystrophy, suggesting AAA-ATPase region is a hypermutable region in patients with a retinal dystrophy; third, there are no significant differences between PEX1-, PEX6-, and PEX26-associated phenotypes. CONCLUSION Next-generation sequencing is important for the diagnosis of HS. This study expands the clinical and genetic spectrum of HS, and provides additional insights into genotype-phenotype correlations, which is vital for accurate clinical practice, genetic counseling, and pathogenesis studies.
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Affiliation(s)
- Feng-Juan Gao
- Eye Institute, Eye and ENT Hospital, College of Medicine, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China.,Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, National Health Commission, Shanghai, China
| | - Fang-Yuan Hu
- Eye Institute, Eye and ENT Hospital, College of Medicine, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China.,Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, National Health Commission, Shanghai, China
| | - Ping Xu
- Eye Institute, Eye and ENT Hospital, College of Medicine, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China.,Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, National Health Commission, Shanghai, China
| | - Yu-He Qi
- Eye Institute, Eye and ENT Hospital, College of Medicine, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China.,Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, National Health Commission, Shanghai, China
| | - Jian-Kang Li
- BGI-Shenzhen, Shenzhen, China.,Department of Computer Science, City University of Hong Kong, 83 Tat Chee Ave, Kowloon, Hong Kong
| | - Yong-Jin Zhang
- Eye Institute, Eye and ENT Hospital, College of Medicine, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China.,Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, National Health Commission, Shanghai, China
| | - Fang Chen
- BGI-Shenzhen, Shenzhen, China.,Laboratory of Genomics and Molecular Biomedicine, Department of Biology, University of Copenhagen, Copenhagen, Denmark.,Shenzhen Engineering Laboratory for Birth Defects Screening, BGI-Shenzhen, Shenzhen, China
| | - Qing Chang
- Eye Institute, Eye and ENT Hospital, College of Medicine, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China.,Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, National Health Commission, Shanghai, China
| | - Fang Song
- Eye Institute, Eye and ENT Hospital, College of Medicine, Fudan University, Shanghai, China
| | | | - Ge-Zhi Xu
- Eye Institute, Eye and ENT Hospital, College of Medicine, Fudan University, Shanghai, China. .,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China. .,Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, National Health Commission, Shanghai, China.
| | - Ji-Hong Wu
- Eye Institute, Eye and ENT Hospital, College of Medicine, Fudan University, Shanghai, China. .,Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Shanghai, China. .,Key Laboratory of Myopia (Fudan University), Chinese Academy of Medical Sciences, National Health Commission, Shanghai, China.
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9
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Olmedilla A, Sandalio LM. Selective Autophagy of Peroxisomes in Plants: From Housekeeping to Development and Stress Responses. FRONTIERS IN PLANT SCIENCE 2019; 10:1021. [PMID: 31555306 PMCID: PMC6722239 DOI: 10.3389/fpls.2019.01021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 07/22/2019] [Indexed: 05/21/2023]
Abstract
Peroxisomes are dynamic organelles involved in multiple functions, including oxygen and nitrogen reactive species metabolism. In plants, these organelles have a close relationship with chloroplasts and mitochondria, characterized by intense metabolic activity and signal transduction. Peroxisomes undergo rapid changes in size, morphology, and abundance depending on the plant development stage and environmental conditions. As peroxisomes are essential not only for redox homeostasis but also for sensing stress, signaling transduction, and cell survival, their formation and degradation need to be rigorously regulated. In this review, new insights into the regulation of plant peroxisomes are briefly described, with a particular emphasis on pexophagy components and their regulation.
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Affiliation(s)
- Adela Olmedilla
- Department of Biochemistry and Molecular and Cellular Biology of Plants, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
| | - Luisa M. Sandalio
- Department of Biochemistry and Molecular and Cellular Biology of Plants, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
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10
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Burkhart SE, Llinas RJ, Bartel B. PEX16 contributions to peroxisome import and metabolism revealed by viable Arabidopsis pex16 mutants. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2019; 61:853-870. [PMID: 30761735 PMCID: PMC6613983 DOI: 10.1111/jipb.12789] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 02/10/2019] [Indexed: 06/09/2023]
Abstract
Peroxisomes rely on peroxins (PEX proteins) for biogenesis, importing membrane and matrix proteins, and fission. PEX16, which is implicated in peroxisomal membrane protein targeting and forming nascent peroxisomes from the endoplasmic reticulum (ER), is unusual among peroxins because it is inserted co-translationally into the ER and localizes to both ER and peroxisomal membranes. PEX16 mutations in humans, yeast, and plants confer some common peroxisomal defects; however, apparent functional differences have impeded the development of a unified model for PEX16 action. The only reported pex16 mutant in plants, the Arabidopsis shrunken seed1 mutant, is inviable, complicating analysis of PEX16 function after embryogenesis. Here, we characterized two viable Arabidopsis pex16 alleles that accumulate negligible PEX16 protein levels. Both mutants displayed impaired peroxisome function - slowed consumption of stored oil bodies, decreased import of matrix proteins, and increased peroxisome size. Moreover, one pex16 allele exhibited reduced growth that could be alleviated by an external fixed carbon source, decreased responsiveness to peroxisomally processed hormone precursors, and worsened or improved peroxisome function in combination with other pex mutants. Because the mutations impact different regions of the PEX16 gene, these viable pex16 alleles allow assessment of the importance of Arabidopsis PEX16 and its functional domains.
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Patel KJ, Kao Y, Llinas RJ, Bartel B. A PEX5 missense allele preferentially disrupts PTS1 cargo import into Arabidopsis peroxisomes. PLANT DIRECT 2019; 3:e00128. [PMID: 31236542 PMCID: PMC6508846 DOI: 10.1002/pld3.128] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 01/09/2019] [Accepted: 03/03/2019] [Indexed: 06/09/2023]
Abstract
The sorting of eukaryotic proteins to various organellar destinations requires receptors that recognize cargo protein targeting signals and facilitate transport into the organelle. One such receptor is the peroxin PEX5, which recruits cytosolic cargo carrying a peroxisome-targeting signal (PTS) type 1 (PTS1) for delivery into the peroxisomal lumen (matrix). In plants and mammals, PEX5 is also indirectly required for peroxisomal import of proteins carrying a PTS2 signal because PEX5 binds the PTS2 receptor, bringing the associated PTS2 cargo to the peroxisome along with PTS1 cargo. Despite PEX5 being the PTS1 cargo receptor, previously identified Arabidopsis pex5 mutants display either impairment of both PTS1 and PTS2 import or defects only in PTS2 import. Here we report the first Arabidopsis pex5 mutant with an exclusive PTS1 import defect. In addition to markedly diminished GFP-PTS1 import and decreased pex5-2 protein accumulation, this pex5-2 mutant shows typical peroxisome-related defects, including inefficient β-oxidation and reduced growth. Growth at reduced or elevated temperatures ameliorated or exacerbated pex5-2 peroxisome-related defects, respectively, without markedly changing pex5-2 protein levels. In contrast to the diminished PTS1 import, PTS2 processing was only slightly impaired and PTS2-GFP import appeared normal in pex5-2. This finding suggests that even minor peroxisomal localization of the PTS1 protein DEG15, the PTS2-processing protease, is sufficient to maintain robust PTS2 processing.
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Affiliation(s)
- Khushali J. Patel
- Department of BioSciencesRice UniversityHoustonTexas
- Present address:
Graduate School of Biomedical SciencesBaylor College of MedicineHoustonTexas
| | - Yun‐Ting Kao
- Department of BioSciencesRice UniversityHoustonTexas
- Present address:
Department of Cell Biology and Molecular GeneticsUniversity of MarylandCollege ParkMaryland
| | | | - Bonnie Bartel
- Department of BioSciencesRice UniversityHoustonTexas
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Young PG, Passalacqua MJ, Chappell K, Llinas RJ, Bartel B. A facile forward-genetic screen for Arabidopsis autophagy mutants reveals twenty-one loss-of-function mutations disrupting six ATG genes. Autophagy 2019; 15:941-959. [PMID: 30734619 PMCID: PMC6526838 DOI: 10.1080/15548627.2019.1569915] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Macroautophagy is a process through which eukaryotic cells degrade large substrates including organelles, protein aggregates, and invading pathogens. Over 40 autophagy-related (ATG) genes have been identified through forward-genetic screens in yeast. Although homology-based analyses have identified conserved ATG genes in plants, only a few atg mutants have emerged from forward-genetic screens in Arabidopsis thaliana. We developed a screen that consistently recovers Arabidopsis atg mutations by exploiting mutants with defective LON2/At5g47040, a protease implicated in peroxisomal quality control. Arabidopsis lon2 mutants exhibit reduced responsiveness to the peroxisomally-metabolized auxin precursor indole-3-butyric acid (IBA), heightened degradation of several peroxisomal matrix proteins, and impaired processing of proteins harboring N-terminal peroxisomal targeting signals; these defects are ameliorated by preventing autophagy. We optimized a lon2 suppressor screen to expedite recovery of additional atg mutants. After screening mutagenized lon2-2 seedlings for restored IBA responsiveness, we evaluated stabilization and processing of peroxisomal proteins, levels of several ATG proteins, and levels of the selective autophagy receptor NBR1/At4g24690, which accumulates when autophagy is impaired. We recovered 21 alleles disrupting 6 ATG genes: ATG2/At3g19190, ATG3/At5g61500, ATG5/At5g17290, ATG7/At5g45900, ATG16/At5g50230, and ATG18a/At3g62770. Twenty alleles were novel, and 3 of the mutated genes lack T-DNA insertional alleles in publicly available repositories. We also demonstrate that an insertional atg11/At4g30790 allele incompletely suppresses lon2 defects. Finally, we show that NBR1 is not necessary for autophagy of lon2 peroxisomes and that NBR1 overexpression is not sufficient to trigger autophagy of seedling peroxisomes, indicating that Arabidopsis can use an NBR1-independent mechanism to target peroxisomes for autophagic degradation. Abbreviations: ATG: autophagy-related; ATI: ATG8-interacting protein; Col-0: Columbia-0; DSK2: dominant suppressor of KAR2; EMS: ethyl methanesulfonate; GFP: green fluorescent protein; IAA: indole-3-acetic acid; IBA: indole-3-butyric acid; ICL: isocitrate lyase; MLS: malate synthase; NBR1: Next to BRCA1 gene 1; PEX: peroxin; PMDH: peroxisomal malate dehydrogenase; PTS: peroxisomal targeting signal; thiolase: 3-ketoacyl-CoA thiolase; UBA: ubiquitin-associated; WT: wild type
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Affiliation(s)
- Pierce G Young
- a Department of Biosciences , Rice University , Houston , TX , USA
| | | | - Kevin Chappell
- a Department of Biosciences , Rice University , Houston , TX , USA.,b Department of Biology , University of Mary Hardin-Baylor , Belton , TX , USA
| | - Roxanna J Llinas
- a Department of Biosciences , Rice University , Houston , TX , USA
| | - Bonnie Bartel
- a Department of Biosciences , Rice University , Houston , TX , USA
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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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Luo M, Zhuang X. Review: Selective degradation of peroxisome by autophagy in plants: Mechanisms, functions, and perspectives. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2018; 274:485-491. [PMID: 30080638 DOI: 10.1016/j.plantsci.2018.06.026] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 06/28/2018] [Accepted: 06/29/2018] [Indexed: 06/08/2023]
Abstract
Peroxisome, a single-membrane organelle conserved in eukaryotic, is responsible for a series of oxidative reactions with its specific enzymatic components. A counterbalance between peroxisome biogenesis and degradation is crucial for the homeostasis of peroxisomes. One such degradation mechanism, termed pexophagy, is a type of selective autophagic process to deliver the excess/damaged peroxisomes into the vacuole. In plants, pexophagy is involved in the remodeling of seedlings and quality control of peroxisomes. Here, we describe the recent advance in plant pexophagy, with a focus to discuss the key regulators in plants in comparison with those in yeast and mammals, as well as future directions for pexophagy studies in plants.
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Affiliation(s)
- Mengqian Luo
- Centre for Cell & Developmental Biology, State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Xiaohong Zhuang
- Centre for Cell & Developmental Biology, State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
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