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Shao X, Xu H, Pimpl P. Nanobody-based VSR7 tracing shows clathrin-dependent TGN to Golgi recycling. Nat Commun 2023; 14:6926. [PMID: 37903761 PMCID: PMC10616157 DOI: 10.1038/s41467-023-42331-1] [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: 03/07/2023] [Accepted: 10/06/2023] [Indexed: 11/01/2023] Open
Abstract
Receptor-mediated transport of soluble proteins is nature's key to empowering eukaryotic cells to access a plethora of macromolecules, either by direct accumulation or as products from resulting biochemical pathways. The transport efficiency of these mechanisms results from the receptor's capability to capture, transport, and release ligands on the one hand and the cycling ability that allows for performing multiple rounds of ligand transport on the other. However, the plant VACUOLAR SORTING RECEPTOR (VSR) protein family is diverse, and their ligand-specificity and bidirectional trafficking routes and transport mechanisms remain highly controversial. Here we employ nanobody-epitope interaction-based molecular tools to assess the function of the VSR 7 in vivo. We demonstrate the specificity of the VSR7 for sequence-specific vacuolar sorting signals, and we trace its anterograde transport and retrograde recycling route. VSR7 localizes at the cis-Golgi apparatus at steady state conditions and transports ligands downstream to release them in the trans-Golgi network/early endosome (TGN/EE) before undergoing clathrin-dependent recycling from the TGN/EE back to the cis-Golgi.
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Affiliation(s)
- Xiaoyu Shao
- Harbin Institute of Technology, Harbin, China
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, Department of Biology, School of Life Sciences, Southern University of Science and Technology (SUSTech), Shenzhen, Guangdong, 518055, China
| | - Hao Xu
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, Department of Biology, School of Life Sciences, Southern University of Science and Technology (SUSTech), Shenzhen, Guangdong, 518055, China
| | - Peter Pimpl
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, Department of Biology, School of Life Sciences, Southern University of Science and Technology (SUSTech), Shenzhen, Guangdong, 518055, China.
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2
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Zeng Y, Liang Z, Liu Z, Li B, Cui Y, Gao C, Shen J, Wang X, Zhao Q, Zhuang X, Erdmann PS, Wong KB, Jiang L. Recent advances in plant endomembrane research and new microscopical techniques. THE NEW PHYTOLOGIST 2023; 240:41-60. [PMID: 37507353 DOI: 10.1111/nph.19134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 06/19/2023] [Indexed: 07/30/2023]
Abstract
The endomembrane system consists of various membrane-bound organelles including the endoplasmic reticulum (ER), Golgi apparatus, trans-Golgi network (TGN), endosomes, and the lysosome/vacuole. Membrane trafficking between distinct compartments is mainly achieved by vesicular transport. As the endomembrane compartments and the machineries regulating the membrane trafficking are largely conserved across all eukaryotes, our current knowledge on organelle biogenesis and endomembrane trafficking in plants has mainly been shaped by corresponding studies in mammals and yeast. However, unique perspectives have emerged from plant cell biology research through the characterization of plant-specific regulators as well as the development and application of the state-of-the-art microscopical techniques. In this review, we summarize our current knowledge on the plant endomembrane system, with a focus on several distinct pathways: ER-to-Golgi transport, protein sorting at the TGN, endosomal sorting on multivesicular bodies, vacuolar trafficking/vacuole biogenesis, and the autophagy pathway. We also give an update on advanced imaging techniques for the plant cell biology research.
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Affiliation(s)
- Yonglun Zeng
- School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Zizhen Liang
- School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Zhiqi Liu
- School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Baiying Li
- School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Yong Cui
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, 361102, China
| | - Caiji Gao
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, 510631, China
| | - Jinbo Shen
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, 311300, China
| | - Xiangfeng Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Qiong Zhao
- School of Life Sciences, East China Normal University, Shanghai, 200062, China
| | - Xiaohong Zhuang
- School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Philipp S Erdmann
- Human Technopole, Viale Rita Levi-Montalcini, 1, Milan, I-20157, Italy
| | - Kam-Bo Wong
- Centre for Protein Science and Crystallography, School of Life Sciences, The Chinese University of Hong Kong (CUHK), Shatin, Hong Kong, China
| | - Liwen Jiang
- School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
- The CUHK Shenzhen Research Institute, Shenzhen, 518057, China
- Institute of Plant Molecular Biology and Agricultural Biotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong, China
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3
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Luo M, Law KC, He Y, Chung KK, Po MK, Feng L, Chung KP, Gao C, Zhuang X, Jiang L. Arabidopsis AUTOPHAGY-RELATED2 is essential for ATG18a and ATG9 trafficking during autophagosome closure. PLANT PHYSIOLOGY 2023; 193:304-321. [PMID: 37195145 DOI: 10.1093/plphys/kiad287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 04/25/2023] [Accepted: 04/27/2023] [Indexed: 05/18/2023]
Abstract
As a fundamental metabolic pathway, autophagy plays important roles in plant growth and development, particularly under stress conditions. A set of autophagy-related (ATG) proteins is recruited for the formation of a double-membrane autophagosome. Among them, the essential roles of ATG2, ATG18, and ATG9 have been well established in plant autophagy via genetic analysis; however, the underlying molecular mechanism for ATG2 in plant autophagosome formation remains poorly understood. In this study, we focused on the specific role of ATG2 in the trafficking of ATG18a and ATG9 during autophagy in Arabidopsis (Arabidopsis thaliana). Under normal conditions, YFP-ATG18a proteins are partially localized on late endosomes and translocated to ATG8e-labeled autophagosomes upon autophagic induction. Real-time imaging analysis revealed sequential recruitment of ATG18a on the phagophore membrane, showing that ATG18a specifically decorated the closing edges and finally disassociated from the completed autophagosome. However, in the absence of ATG2, most of the YFP-ATG18a proteins are arrested on autophagosomal membranes. Ultrastructural and 3D tomography analysis showed that unclosed autophagosome structures are accumulated in the atg2 mutant, displaying direct connections with the endoplasmic reticulum membrane and vesicular structures. Dynamic analysis of ATG9 vesicles suggested that ATG2 depletion also affects the association between ATG9 vesicles and the autophagosomal membrane. Furthermore, using interaction and recruitment analysis, we mapped the interaction relationship between ATG2 and ATG18a, implying a possible role of ATG18a in recruiting ATG2 and ATG9 to the membrane. Our findings unveil a specific role of ATG2 in coordinating ATG18a and ATG9 trafficking to mediate autophagosome closure in Arabidopsis.
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Affiliation(s)
- Mengqian Luo
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Kai Ching Law
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Yilin He
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Ka Kit Chung
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Muk Kuen Po
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Lanlan Feng
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Kin Pan Chung
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Caiji Gao
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Xiaohong Zhuang
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Liwen Jiang
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
- CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen 518057, China
- Institute of Plant Molecular Biology and Agricultural Biotechnology, The Chinese University of Hong Kong, Hong Kong, China
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Zouhar J, Cao W, Shen J, Rojo E. Retrograde transport in plants: Circular economy in the endomembrane system. Eur J Cell Biol 2023; 102:151309. [PMID: 36933283 DOI: 10.1016/j.ejcb.2023.151309] [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: 12/08/2022] [Revised: 02/09/2023] [Accepted: 03/11/2023] [Indexed: 03/14/2023] Open
Abstract
The study of endomembrane trafficking is crucial for understanding how cells and whole organisms function. Moreover, there is a special interest in investigating endomembrane trafficking in plants, given its role in transport and accumulation of seed storage proteins and in secretion of cell wall material, arguably the two most essential commodities obtained from crops. The mechanisms of anterograde transport in the biosynthetic and endocytic pathways of plants have been thoroughly discussed in recent reviews, but, comparatively, retrograde trafficking pathways have received less attention. Retrograde trafficking is essential to recover membranes, retrieve proteins that have escaped from their intended localization, maintain homeostasis in maturing compartments, and recycle trafficking machinery for its reuse in anterograde transport reactions. Here, we review the current understanding on retrograde trafficking pathways in the endomembrane system of plants, discussing their integration with anterograde transport routes, describing conserved and plant-specific retrieval mechanisms at play, highlighting contentious issues and identifying open questions for future research.
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Affiliation(s)
- Jan Zouhar
- Central European Institute of Technology, Mendel University in Brno, CZ-61300 Brno, Czech Republic.
| | - Wenhan Cao
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, 311300 Hangzhou, China
| | - Jinbo Shen
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, 311300 Hangzhou, China.
| | - Enrique Rojo
- Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Cantoblanco, E-28049 Madrid, Spain.
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5
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Sun S, Feng L, Chung KP, Lee KM, Cheung HHY, Luo M, Ren K, Law KC, Jiang L, Wong KB, Zhuang X. Mechanistic insights into an atypical interaction between ATG8 and SH3P2 in Arabidopsis thaliana. Autophagy 2022; 18:1350-1366. [PMID: 34657568 PMCID: PMC9225624 DOI: 10.1080/15548627.2021.1976965] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
In selective macroautophagy/autophagy, cargo receptors are recruited to the forming autophagosome by interacting with Atg8 (autophagy-related 8)-family proteins and facilitate the selective sequestration of specific cargoes for autophagic degradation. In addition, Atg8 interacts with a number of adaptors essential for autophagosome biogenesis, including ATG and non-ATG proteins. The majority of these adaptors and receptors are characterized by an Atg8-family interacting motif (AIM) for binding to Atg8. However, the molecular basis for the interaction mode between ATG8 and regulators or cargo receptors in plants remains largely unclear. In this study, we unveiled an atypical interaction mode for Arabidopsis ATG8f with a plant unique adaptor protein, SH3P2 (SH3 domain-containing protein 2), but not with the other two SH3 proteins. By structure analysis of the unbound form of ATG8f, we identified the unique conformational changes in ATG8f upon binding to the AIM sequence of a plant known autophagic receptor, NBR1. To compare the binding affinity of SH3P2-ATG8f with that of ATG8f-NBR1, we performed a gel filtration assay to show that ubiquitin-associated domain of NBR1 outcompetes the SH3 domain of SH3P2 for ATG8f interaction. Biochemical and cellular analysis revealed that distinct interfaces were employed by ATG8f to interact with NBR1 and SH3P2. Further subcellular analysis showed that the AIM-like motif of SH3P2 is essential for its recruitment to the phagophore membrane but is dispensable for its trafficking in endocytosis. Taken together, our study provides an insightful structural basis for the ATG8 binding specificity toward a plant-specific autophagic adaptor and a conserved autophagic receptor.Abbreviations: ATG, autophagy-related; AIM, Atg8-family interacting motif; BAR, Bin-Amphiphysin-Rvs; BFA, brefeldin A; BTH, benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester; CCV, clathrin-coated-vesicle; CLC2, clathrin light chain 2; Conc A, concanamycin A; ER, endoplasmic reticulum; LDS, LIR docking site; MAP1LC3/LC3, microtubule associated protein 1 light chain 3; LIR, LC3-interacting region; PE, phosphatidylethanolamine; SH3P2, SH3 domain containing protein 2; SH3, Src-Homology-3; UBA, ubiquitin-associated; UIM, ubiquitin-interacting motif.
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Affiliation(s)
- Shuangli Sun
- Centre for Protein Science and Crystallography, State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Lanlan Feng
- Centre for Cell and Developmental Biology, State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Kin Pan Chung
- Centre for Cell and Developmental Biology, State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China,Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Ka-Ming Lee
- Centre for Protein Science and Crystallography, State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Hayley Hei-Yin Cheung
- Centre for Protein Science and Crystallography, State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Mengqian Luo
- Centre for Cell and Developmental Biology, State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Kaike Ren
- Centre for Cell and Developmental Biology, State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Kai Ching Law
- Centre for Cell and Developmental Biology, State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Liwen Jiang
- Centre for Cell and Developmental Biology, State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China,The Chinese University of Hong Kong Shenzhen Research Institute, Shenzhen, China
| | - Kam-Bo Wong
- Centre for Protein Science and Crystallography, State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Xiaohong Zhuang
- Centre for Cell and Developmental Biology, State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China,CONTACT Xiaohong Zhuang Centre for Cell and Developmental Biology, State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
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Zheng P, Zheng C, Otegui MS, Li F. Endomembrane mediated-trafficking of seed storage proteins: from Arabidopsis to cereal crops. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:1312-1326. [PMID: 34849750 DOI: 10.1093/jxb/erab519] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 11/25/2021] [Indexed: 06/13/2023]
Abstract
Seed storage proteins (SSPs) are of great importance in plant science and agriculture, particularly in cereal crops, due to their nutritional value and their impact on food properties. During seed maturation, massive amounts of SSPs are synthesized and deposited either within protein bodies derived from the endoplasmic reticulum, or into specialized protein storage vacuoles (PSVs). The processing and trafficking of SSPs vary among plant species, tissues, and even developmental stages, as well as being influenced by SSP composition. The different trafficking routes, which affect the amount of SSPs that seeds accumulate and their composition and modifications, rely on a highly dynamic and functionally specialized endomembrane system. Although the general steps in SSP trafficking have been studied in various plants, including cereals, the detailed underlying molecular and regulatory mechanisms are still elusive. In this review, we discuss the main endomembrane routes involved in SSP trafficking to the PSV in Arabidopsis and other eudicots, and compare and contrast the SSP trafficking pathways in major cereal crops, particularly in rice and maize. In addition, we explore the challenges and strategies for analyzing the endomembrane system in cereal crops.
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Affiliation(s)
- Ping Zheng
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou, China
- School of Life Science, Huizhou University, Huizhou, China
| | - Chunyan Zheng
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou, China
| | - Marisa S Otegui
- Department of Botany, Center for Quantitative Cell Imaging, University of Wisconsin-Madison, WIUSA
| | - Faqiang Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou, China
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Wang J, Li L, Li C, Yang X, Xue Y, Zhu Z, Mao X, Jing R. A transposon in the vacuolar sorting receptor gene TaVSR1-B promoter region is associated with wheat root depth at booting stage. PLANT BIOTECHNOLOGY JOURNAL 2021; 19:1456-1467. [PMID: 33555662 PMCID: PMC8313126 DOI: 10.1111/pbi.13564] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 01/06/2021] [Accepted: 01/28/2021] [Indexed: 05/14/2023]
Abstract
Root depth, as an important component of root architecture, plays a significant role in growth, grain yield determination and abiotic stress tolerance in crop plants, but its genetic basis remains poorly elucidated. In this study, a panel composed of 323 wheat (Triticum aestivum L.) accessions was assessed for variation in root depth and genotyped with the Wheat 660K SNP Array. GWAS (genome-wide association study) detected significant association between a 125 bp miniature inverted-repeat transposable element (MITE) in the promoter of the TaVSR1-B gene with root depth at the booting stage. We showed that the MITE repressed TaVSR1-B expression by DNA methylation and H3K27 tri-methylation. The roles of TaVSR1-B in root growth were verified by altered expression of the gene in transgenic wheat, rice and a tavsr1 TILLING mutant. Increased TaVSR1-B expression made the root elongation zone shorter and the differentiation zone longer, leading to deeper root. This work provides novel insight into the genetic basis of variation in root depth and a promising target for genetic improvement of root architecture in wheat.
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Affiliation(s)
- Jingyi Wang
- National Key Facility for Crop Gene Resources and Genetic Improvement/Institute of Crop SciencesChinese Academy of Agricultural SciencesBeijingChina
| | - Long Li
- National Key Facility for Crop Gene Resources and Genetic Improvement/Institute of Crop SciencesChinese Academy of Agricultural SciencesBeijingChina
| | - Chaonan Li
- National Key Facility for Crop Gene Resources and Genetic Improvement/Institute of Crop SciencesChinese Academy of Agricultural SciencesBeijingChina
| | - Xi Yang
- National Key Facility for Crop Gene Resources and Genetic Improvement/Institute of Crop SciencesChinese Academy of Agricultural SciencesBeijingChina
| | - Yinghong Xue
- National Key Facility for Crop Gene Resources and Genetic Improvement/Institute of Crop SciencesChinese Academy of Agricultural SciencesBeijingChina
| | - Zhi Zhu
- National Key Facility for Crop Gene Resources and Genetic Improvement/Institute of Crop SciencesChinese Academy of Agricultural SciencesBeijingChina
| | - Xinguo Mao
- National Key Facility for Crop Gene Resources and Genetic Improvement/Institute of Crop SciencesChinese Academy of Agricultural SciencesBeijingChina
| | - Ruilian Jing
- National Key Facility for Crop Gene Resources and Genetic Improvement/Institute of Crop SciencesChinese Academy of Agricultural SciencesBeijingChina
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8
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Zhang X, Li H, Lu H, Hwang I. The trafficking machinery of lytic and protein storage vacuoles: how much is shared and how much is distinct? JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:3504-3512. [PMID: 33587748 DOI: 10.1093/jxb/erab067] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 02/10/2021] [Indexed: 05/10/2023]
Abstract
Plant cells contain two types of vacuoles, the lytic vacuole (LV) and protein storage vacuole (PSV). LVs are present in vegetative cells, whereas PSVs are found in seed cells. The physiological functions of the two types of vacuole differ. Newly synthesized proteins must be transported to these vacuoles via protein trafficking through the endomembrane system for them to function. Recently, significant advances have been made in elucidating the molecular mechanisms of protein trafficking to these organelles. Despite these advances, the relationship between the trafficking mechanisms to the LV and PSV remains unclear. Some aspects of the trafficking mechanisms are common to both types of vacuole, but certain aspects are specific to trafficking to either the LV or PSV. In this review, we summarize recent findings on the components involved in protein trafficking to both the LV and PSV and compare them to examine the extent of overlap in the trafficking mechanisms. In addition, we discuss the interconnection between the LV and PSV provided by the protein trafficking machinery and the implications for the identity of these organelles.
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Affiliation(s)
- Xiuxiu Zhang
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing 100083, China
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
| | - Hui Li
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing 100083, China
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
| | - Hai Lu
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing 100083, China
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
| | - Inhwan Hwang
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing 100083, China
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
- Department of Life Sciences, Pohang University of Science and Technology, 37673 Pohang, South Korea
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9
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Zhang M, Hu S, Yi F, Gao Y, Zhu D, Wang Y, Cai Y, Hou D, Lin X, Shen J. Organelle Visualization With Multicolored Fluorescent Markers in Bamboo. FRONTIERS IN PLANT SCIENCE 2021; 12:658836. [PMID: 33936145 PMCID: PMC8081836 DOI: 10.3389/fpls.2021.658836] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 03/12/2021] [Indexed: 05/03/2023]
Abstract
Bamboo is an important model plant to study the molecular mechanisms of rapid shoot growth and flowering once in a lifetime. However, bamboo research about protein functional characterization is largely lagged behind, mainly due to the lack of gene transformation platforms. In this study, a protoplast transient gene expression system in moso bamboo has been first established. Using this reliable and efficient system, we have generated a set of multicolored fluorescent markers based on the targeting sequences from endogenous proteins, which have been validated by their comparative localization with Arabidopsis organelle markers, in a combination with pharmaceutical treatments. Moreover, we further demonstrated the power of this multicolor marker set for rapid, combinatorial analysis of the subcellular localization of uncharacterized proteins, which may play potential functions in moso bamboo flowering and fast growth of shoots. Finally, this protoplast transient gene expression system has been elucidated for functional analysis in protein-protein interaction by fluorescence resonance energy transfer (FRET) and co-immunoprecipitation analysis. Taken together, in combination with the set of moso bamboo organelle markers, the protoplast transient gene expression system could be used for subcellular localization and functional study of unknown proteins in bamboo and will definitely promote rapid progress in diverse areas of research in bamboo plants.
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Affiliation(s)
- Mengdi Zhang
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, China
| | - Shuai Hu
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, China
| | - Fang Yi
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, China
| | - Yanli Gao
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, China
| | - Dongmei Zhu
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, China
| | - Yizhu Wang
- College of Life Science, Sichuan Agricultural University, Ya'an, China
| | - Yi Cai
- College of Life Science, Sichuan Agricultural University, Ya'an, China
| | - Dan Hou
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, China
| | - Xinchun Lin
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, China
| | - Jinbo Shen
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, China
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10
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Ivanov R, Robinson DG. EMAC, Retromer, and VSRs: do they connect? PROTOPLASMA 2020; 257:1725-1729. [PMID: 32780164 PMCID: PMC8286218 DOI: 10.1007/s00709-020-01543-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Accepted: 08/06/2020] [Indexed: 06/02/2023]
Abstract
Eukaryotic organisms share many common features in terms of endomembrane trafficking. This fact has helped plant scientists to propose testable hypotheses on how plant intracellular membrane trafficking is achieved and regulated based on knowledge from yeast and mammals. However, when a new compartment has been identified in a plant cell that has a vesicle tethering complex located at a position which is completely different to its counterpart in yeast and mammalian cells, caution is demanded when interpreting possible interactions with other trafficking elements. This is exemplified by the recently discovered EMAC (ER and microtubule-associated compartment). It has been postulated that this compartment is the recipient of vacuolar sorting receptors (VSRs) transported retrogradely via "retromer vesicles" from a post-Golgi location. Unfortunately, this suggestion was based entirely on our knowledge of retromer from yeast and mammalian cells, and did not take into account the available literature on the composition, localization, and function of the plant retromer. It also lacked reference to recent contradictory findings on VSR trafficking. In this short article, we have tried to rectify this situation, pointing out that plant retromer may not function as a pentameric complex of two subunits: the retromer core and the sorting nexins.
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Affiliation(s)
- Rumen Ivanov
- Institute of Botany, Heinrich Heine University, 40225, Düsseldorf, Germany.
| | - David G Robinson
- Centre for Organismal Studies, University of Heidelberg, 69117, Heidelberg, Germany
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11
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On the discovery of an endomembrane compartment in plants. Proc Natl Acad Sci U S A 2020; 117:10623-10624. [PMID: 32376631 DOI: 10.1073/pnas.2006766117] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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12
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Hu S, Li Y, Shen J. A Diverse Membrane Interaction Network for Plant Multivesicular Bodies: Roles in Proteins Vacuolar Delivery and Unconventional Secretion. FRONTIERS IN PLANT SCIENCE 2020; 11:425. [PMID: 32425960 PMCID: PMC7203423 DOI: 10.3389/fpls.2020.00425] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 03/24/2020] [Indexed: 05/15/2023]
Abstract
Vesicle trafficking between the membrane-bound organelles in plant cells plays crucial roles in the precise transportation of various materials, and thus supports cell proliferation and cellular polarization. Conventionally, plant prevacuolar compartments (PVCs), identified as multivesicular bodies (MVBs), play important roles in both the secretory pathway as intermediate compartments and the endocytic pathway as late endosomes. In recent years, the PVC/MVBs have been proposed to play important roles in both protein vacuolar delivery and unconventional secretion, but several important questions on the new regulators and environmental cues that coordinate the PVC/MVB-organelle membrane interactions and their biological significances remain. In this review, we first summarize the identity and nature of the plant PVC/MVBs, and then we present an update on our current understanding on the interaction of PVC/MVBs with other organelles in the plant endomembrane system with focus on the vacuole, autophagosome, and plasma membrane (PM) in plant development and stress responses. Finally, we raise some open questions and present future perspectives in the study of PVC/MVB-organelle interactions and associated biological functions.
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13
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Zhu D, Zhang M, Gao C, Shen J. Protein trafficking in plant cells: Tools and markers. SCIENCE CHINA-LIFE SCIENCES 2019; 63:343-363. [DOI: 10.1007/s11427-019-9598-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Accepted: 07/22/2019] [Indexed: 12/26/2022]
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14
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Früholz S, Fäßler F, Kolukisaoglu Ü, Pimpl P. Nanobody-triggered lockdown of VSRs reveals ligand reloading in the Golgi. Nat Commun 2018; 9:643. [PMID: 29440677 PMCID: PMC5811495 DOI: 10.1038/s41467-018-02909-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2017] [Accepted: 01/08/2018] [Indexed: 11/17/2022] Open
Abstract
Protein degradation in lytic compartments is crucial for eukaryotic cells. At the heart of this process, vacuolar sorting receptors (VSRs) bind soluble hydrolases in the secretory pathway and release them into the vacuolar route. Sorting efficiency is suggested to result from receptor recycling. However, how and to where plant VSRs recycle remains controversial. Here we present a nanobody-epitope interaction-based protein labeling and tracking approach to dissect their anterograde and retrograde transport routes in vivo. We simultaneously employ two different nanobody-epitope pairs: one for the location-specific post-translational fluorescence labeling of receptors and the other pair to trigger their compartment-specific lockdown via an endocytosed dual-epitope linker protein. We demonstrate VSR recycling from the TGN/EE, thereby identifying the cis-Golgi as the recycling target and show that recycled VSRs reload ligands. This is evidence that bidirectional VSR-mediated sorting of vacuolar proteins exists and occurs between the Golgi and the TGN/EE.
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Affiliation(s)
- Simone Früholz
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Auf der Morgenstelle 32, 72076, Tübingen, Germany
| | - Florian Fäßler
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Auf der Morgenstelle 32, 72076, Tübingen, Germany
| | - Üner Kolukisaoglu
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Auf der Morgenstelle 32, 72076, Tübingen, Germany
| | - Peter Pimpl
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Auf der Morgenstelle 32, 72076, Tübingen, Germany.
- SUSTech-PKU Institute of Plant and Food Science (IPFS), Department of Biology, Southern University of Science and Technology (SUSTech), 1088 Xueyuan Rd, Shenzhen, 518055, China.
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15
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Früholz S, Fäßler F, Kolukisaoglu Ü, Pimpl P. Nanobody-triggered lockdown of VSRs reveals ligand reloading in the Golgi. Nat Commun 2018. [PMID: 29440677 DOI: 10.1038/s41467-018-02909-2906] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/24/2023] Open
Abstract
Protein degradation in lytic compartments is crucial for eukaryotic cells. At the heart of this process, vacuolar sorting receptors (VSRs) bind soluble hydrolases in the secretory pathway and release them into the vacuolar route. Sorting efficiency is suggested to result from receptor recycling. However, how and to where plant VSRs recycle remains controversial. Here we present a nanobody-epitope interaction-based protein labeling and tracking approach to dissect their anterograde and retrograde transport routes in vivo. We simultaneously employ two different nanobody-epitope pairs: one for the location-specific post-translational fluorescence labeling of receptors and the other pair to trigger their compartment-specific lockdown via an endocytosed dual-epitope linker protein. We demonstrate VSR recycling from the TGN/EE, thereby identifying the cis-Golgi as the recycling target and show that recycled VSRs reload ligands. This is evidence that bidirectional VSR-mediated sorting of vacuolar proteins exists and occurs between the Golgi and the TGN/EE.
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Affiliation(s)
- Simone Früholz
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Auf der Morgenstelle 32, 72076, Tübingen, Germany
| | - Florian Fäßler
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Auf der Morgenstelle 32, 72076, Tübingen, Germany
| | - Üner Kolukisaoglu
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Auf der Morgenstelle 32, 72076, Tübingen, Germany
| | - Peter Pimpl
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Auf der Morgenstelle 32, 72076, Tübingen, Germany.
- SUSTech-PKU Institute of Plant and Food Science (IPFS), Department of Biology, Southern University of Science and Technology (SUSTech), 1088 Xueyuan Rd, Shenzhen, 518055, China.
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16
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Heucken N, Ivanov R. The retromer, sorting nexins and the plant endomembrane protein trafficking. J Cell Sci 2018; 131:jcs.203695. [PMID: 29061884 DOI: 10.1242/jcs.203695] [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] [Indexed: 12/19/2022] Open
Abstract
Protein sorting in the endomembrane system is responsible for the coordination of cellular functions. Plant intracellular trafficking has its own unique features, which include specific regulatory aspects of endosomal sorting and recycling of cargo proteins, mediated by the retromer complex. Recent work has led to significant progress in understanding the role of Arabidopsis retromer subunits in recycling vacuolar sorting receptors and plasma membrane proteins. As a consequence, members of the sorting nexin (SNX) protein family and their interaction partners have emerged as critical protein trafficking regulators, in particular with regard to adaptation to environmental change, such as temperature fluctuations and nutrient deficiency. In this Review, we discuss the known and proposed functions of the comparatively small Arabidopsis SNX protein family. We review the available information on the role of the three Bin-Amphiphysin-Rvs (BAR)-domain-containing Arabidopsis thaliana (At)SNX proteins and discuss their function in the context of their potential participation in the plant retromer complex. We also summarize the role of AtSNX1-interacting proteins in different aspects of SNX-dependent protein trafficking and comment on the potential function of three novel, as yet unexplored, Arabidopsis SNX proteins.
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Affiliation(s)
- Nicole Heucken
- Institute of Botany, Heinrich-Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany
| | - Rumen Ivanov
- Institute of Botany, Heinrich-Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany
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17
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Bellucci M, De Marchis F, Pompa A. The endoplasmic reticulum is a hub to sort proteins toward unconventional traffic pathways and endosymbiotic organelles. JOURNAL OF EXPERIMENTAL BOTANY 2017; 69:7-20. [PMID: 28992342 DOI: 10.1093/jxb/erx286] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 07/24/2017] [Indexed: 05/25/2023]
Abstract
The discovery that much of the extracellular proteome in eukaryotic cells consists of proteins lacking a signal peptide, which cannot therefore enter the secretory pathway, has led to the identification of alternative protein secretion routes bypassing the Golgi apparatus. However, proteins harboring a signal peptide for translocation into the endoplasmic reticulum can also be transported along these alternative routes, which are still far from being well elucidated in terms of the molecular machineries and subcellular/intermediate compartments involved. In this review, we first try to provide a definition of all the unconventional protein secretion pathways in eukaryotic cells, as those pathways followed by proteins directed to an 'external space' bypassing the Golgi, where 'external space' refers to the extracellular space plus the lumen of the secretory route compartments and the inner space of mitochondria and plastids. Then, we discuss the role of the endoplasmic reticulum in sorting proteins toward unconventional traffic pathways in plants. In this regard, various unconventional pathways exporting proteins from the endoplasmic reticulum to the vacuole, plasma membrane, apoplast, mitochondria, and plastids are described, including the short routes followed by the proteins resident in the endoplasmic reticulum.
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Affiliation(s)
- Michele Bellucci
- Institute of Biosciences and Bioresources, Research Division of Perugia, National Research Council (CNR), Italy
| | - Francesca De Marchis
- Institute of Biosciences and Bioresources, Research Division of Perugia, National Research Council (CNR), Italy
| | - Andrea Pompa
- Institute of Biosciences and Bioresources, Research Division of Perugia, National Research Council (CNR), Italy
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18
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Di Sansebastiano GP, Barozzi F, Piro G, Denecke J, de Marcos Lousa C. Trafficking routes to the plant vacuole: connecting alternative and classical pathways. JOURNAL OF EXPERIMENTAL BOTANY 2017; 69:79-90. [PMID: 29096031 DOI: 10.1093/jxb/erx376] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 09/27/2017] [Indexed: 05/02/2023]
Abstract
Due to the numerous roles plant vacuoles play in cell homeostasis, detoxification, and protein storage, the trafficking pathways to this organelle have been extensively studied. Recent evidence, however, suggests that our vision of transport to the vacuole is not as simple as previously imagined. Alternative routes have been identified and are being characterized. Intricate interconnections between routes seem to occur in various cases, complicating the interpretation of data. In this review, we aim to summarize the published evidence and link the emerging data with previous findings. We discuss the current state of information on alternative and classical trafficking routes to the plant vacuole.
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Affiliation(s)
- Gian Pietro Di Sansebastiano
- DiSTeBA (Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali), University of Salento, Campus ECOTEKNE, Italy
| | - Fabrizio Barozzi
- DiSTeBA (Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali), University of Salento, Campus ECOTEKNE, Italy
| | - Gabriella Piro
- DiSTeBA (Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali), University of Salento, Campus ECOTEKNE, Italy
| | | | - Carine de Marcos Lousa
- Centre for Plant Sciences, Leeds University, UK
- Leeds Beckett University, School of Applied and Clinical Sciences, UK
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19
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Yu F, Xie Q. Non-26S Proteasome Endomembrane Trafficking Pathways in ABA Signaling. TRENDS IN PLANT SCIENCE 2017; 22:976-985. [PMID: 28919033 DOI: 10.1016/j.tplants.2017.08.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 08/24/2017] [Accepted: 08/25/2017] [Indexed: 05/26/2023]
Abstract
The phytohormone abscisic acid (ABA) is a vital endogenous messenger that regulates diverse physiological processes in plants. The regulation of ABA signaling has been well studied at both the transcriptional and translational levels. Post-translational modification of key regulators in ABA signaling by the 26S ubiquitin proteasome pathway is well known. Recently, increasing evidence demonstrates that atypical turnover of key regulators by the endocytic trafficking pathway and autophagy also play vital roles in ABA perception, signaling, and action. We summarize and synthesize here recent findings in the field of ABA signaling.
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Affiliation(s)
- Feifei Yu
- State Key Laboratory of Plant Genomics, National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Number 1 West Beichen Road, Chaoyang District, Beijing 100101, PR China
| | - Qi Xie
- State Key Laboratory of Plant Genomics, National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Number 1 West Beichen Road, Chaoyang District, Beijing 100101, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
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20
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A Secretion System for Cargo Protein Identification of Vacuolar Sorting Receptors. Methods Mol Biol 2017. [PMID: 28861828 DOI: 10.1007/978-1-4939-7262-3_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Vacuolar sorting receptors (VSRs) are type I integral membrane family proteins in plant cells that can sort cargo proteins at the late Golgi or trans-Golgi network (TGN) for vacuolar transport via the prevacuolar compartment (PVC). However, little is known about VSR cargo proteins in plants. Here, we describe a new method for the identification of VSR cargos, which is based on the premise that the expressed N-terminus of VSRs will be secreted into the culture media along with their corresponding cargo proteins. The protocol described here should be applicable to all VSRs and should be also useful for other receptor cargo identification and protein-protein interaction in vivo.
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21
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Konopka-Postupolska D, Clark G. Annexins as Overlooked Regulators of Membrane Trafficking in Plant Cells. Int J Mol Sci 2017; 18:E863. [PMID: 28422051 PMCID: PMC5412444 DOI: 10.3390/ijms18040863] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Revised: 04/03/2017] [Accepted: 04/06/2017] [Indexed: 12/11/2022] Open
Abstract
Annexins are an evolutionary conserved superfamily of proteins able to bind membrane phospholipids in a calcium-dependent manner. Their physiological roles are still being intensively examined and it seems that, despite their general structural similarity, individual proteins are specialized toward specific functions. However, due to their general ability to coordinate membranes in a calcium-sensitive fashion they are thought to participate in membrane flow. In this review, we present a summary of the current understanding of cellular transport in plant cells and consider the possible roles of annexins in different stages of vesicular transport.
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Affiliation(s)
- Dorota Konopka-Postupolska
- Plant Biochemistry Department, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw 02-106, Poland.
| | - Greg Clark
- Molecular, Cell, and Developmental Biology, University of Texas, Austin, TX 78712, USA.
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22
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Floyd BE, Mugume Y, Morriss SC, MacIntosh GC, Bassham DC. Localization of RNS2 ribonuclease to the vacuole is required for its role in cellular homeostasis. PLANTA 2017; 245:779-792. [PMID: 28025674 DOI: 10.1007/s00425-016-2644-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 12/21/2016] [Indexed: 05/28/2023]
Abstract
Localization of the RNase RNS2 to the vacuole via a C-terminal targeting signal is essential for its function in rRNA degradation and homeostasis. RNase T2 ribonucleases are highly conserved enzymes present in the genomes of nearly all eukaryotes and many microorganisms. Their constitutive expression in different tissues and cell types of many organisms suggests a housekeeping role in RNA homeostasis. The Arabidopsis thaliana class II RNase T2, RNS2, is encoded by a single gene and functions in rRNA degradation. Loss of RNS2 results in RNA accumulation and constitutive activation of autophagy, possibly as a compensatory mechanism. While the majority of RNase T2 enzymes is secreted, RNS2 is located within the vacuole and in the endoplasmic reticulum (ER), possibly within ER bodies. As RNS2 has a neutral pH optimum, and the endomembrane organelles are connected by vesicle transport, the site within the endomembrane system at which RNS2 functions is unclear. Here we demonstrate that localization to the vacuole is essential for the physiological function of RNS2. A mutant allele of RNS2, rns2-1, results in production of an active RNS2 RNase but with a mutation that removes a putative C-terminal vacuolar targeting signal. The mutant protein is, therefore, secreted from the cell. This results in a constitutive autophagy phenotype similar to that observed in rns2 null mutants. These findings illustrate that the intracellular retention of RNS2 and localization within the vacuole are critical for its cellular function.
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Affiliation(s)
- Brice E Floyd
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA, 50011, USA
| | - Yosia Mugume
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA, 50011, USA
| | - Stephanie C Morriss
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, 50011, USA
| | - Gustavo C MacIntosh
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, 50011, USA.
| | - Diane C Bassham
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA, 50011, USA.
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23
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Früholz S, Pimpl P. Analysis of Nanobody-Epitope Interactions in Living Cells via Quantitative Protein Transport Assays. Methods Mol Biol 2017; 1662:171-182. [PMID: 28861827 DOI: 10.1007/978-1-4939-7262-3_15] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Over the past few decades, quantitative protein transport analyses have been used to elucidate the sorting and transport of proteins in the endomembrane system of plants. Here, we have applied our knowledge about transport routes and the corresponding sorting signals to establish an in vivo system for testing specific interactions between soluble proteins.Here, we describe the use of quantitative protein transport assays in tobacco mesophyll protoplasts to test for interactions occurring between a GFP-binding nanobody and its GFP epitope. For this, we use a secreted GFP-tagged α-amylase as a reporter together with a vacuolar-targeted RFP-tagged nanobody. The interaction between these proteins is then revealed by a transport alteration of the secretory reporter due to the interaction-triggered attachment of the vacuolar sorting signal.
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Affiliation(s)
- Simone Früholz
- Center for Plant Molecular Biology, University of Tübingen, Auf der Morgenstelle 32, 72076, Tübingen, Germany
| | - Peter Pimpl
- Center for Plant Molecular Biology, University of Tübingen, Auf der Morgenstelle 32, 72076, Tübingen, Germany.
- Department of Biology, Southern University of Science and Technology (SUSTech), Shenzhen, Guangdong, 518055, China.
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24
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Fäßler F, Pimpl P. In Vivo Interaction Studies by Measuring Förster Resonance Energy Transfer Through Fluorescence Lifetime Imaging Microscopy (FRET/FLIM). Methods Mol Biol 2017; 1662:159-170. [PMID: 28861826 DOI: 10.1007/978-1-4939-7262-3_14] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Combinations of multiple fluorescent fusion proteins are commonly generated and used for colocalization studies in live cell imaging but also biochemical analysis of protein-protein interactions by co-immunoprecipitation in vitro. Advanced microscopy techniques like Förster resonance energy transfer through fluorescence lifetime imaging microscopy (FRET/FLIM) nowadays enable the combination of both approaches. This opens up the possibility to perform a location-specific protein-protein interaction analysis in vivo. To this end, the nonradiant energy transfer from a donor to an acceptor fluorophore (FRET) is harnessed to test for close proximity as an indicator for interaction, while the spectromicroscopical measurement of the fluorescence lifetime by FLIM serves as a readout.Here, we describe FRET/FLIM measurements performed with a Leica TCS SP8/PicoHarp 300 combination to demonstrate the interaction between a RFP-tagged GFP-nanobody and its epitope, GFP, in the cytoplasm of tobacco mesophyll protoplasts.
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Affiliation(s)
- Florian Fäßler
- Center for Plant Molecular Biology, University of Tübingen, Auf der Morgenstelle 32, 72076, Tübingen, Germany
| | - Peter Pimpl
- Center for Plant Molecular Biology, University of Tübingen, Auf der Morgenstelle 32, 72076, Tübingen, Germany.
- Department of Biology, Southern University of Science and Technology (SUSTech), Shenzhen, Guangdong, 518055, China.
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25
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Ocampo CG, Lareu JF, Marin Viegas VS, Mangano S, Loos A, Steinkellner H, Petruccelli S. Vacuolar targeting of recombinant antibodies in Nicotiana benthamiana. PLANT BIOTECHNOLOGY JOURNAL 2016; 14:2265-2275. [PMID: 27159528 PMCID: PMC5103231 DOI: 10.1111/pbi.12580] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 04/12/2016] [Accepted: 05/04/2016] [Indexed: 05/31/2023]
Abstract
Plant-based platforms are extensively used for the expression of recombinant proteins, including monoclonal antibodies. However, to harness the approach effectively and leverage it to its full potential, a better understanding of intracellular processes that affect protein properties is required. In this work, we examined vacuolar (vac) targeting and deposition of the monoclonal antibody (Ab) 14D9 in Nicotiana benthamiana leaves. Two distinct vacuolar targeting signals (KISIA and NIFRGF) were C-terminal fused to the heavy chain of 14D9 (vac-Abs) and compared with secreted and ER-retained variants (sec-Ab, ER-Ab, respectively). Accumulation of ER- and vac-Abs was 10- to 15-fold higher than sec-Ab. N-glycan profiling revealed the predominant presence of plant typical complex fucosylated and xylosylated GnGnXF structures on sec-Ab while vac-Abs carried mainly oligomannosidic (Man 7-9) next to GnGnXF forms. Paucimannosidic glycans (commonly assigned as typical vacuolar) were not detected. Confocal microscopy analysis using RFP fusions showed that sec-Ab-RFP localized in the apoplast while vac-Abs-RFP were exclusively detected in the central vacuole. The data suggest that vac-Abs reached the vacuole by two different pathways: direct transport from the ER bypassing the Golgi (Ab molecules containing Man structures) and trafficking through the Golgi (for Ab molecules containing complex N-glycans). Importantly, vac-Abs were correctly assembled and functionally active. Collectively, we show that the central vacuole is an appropriate compartment for the efficient production of Abs with appropriate post-translational modifications, but also point to a reconsideration of current concepts in plant glycan processing.
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Affiliation(s)
- Carolina Gabriela Ocampo
- Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA)Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)Departamento de Ciencias BiológicasFacultad de Ciencias ExactasUniversidad Nacional de La PlataLa PlataArgentina
| | - Jorge Fabricio Lareu
- Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA)Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)Departamento de Ciencias BiológicasFacultad de Ciencias ExactasUniversidad Nacional de La PlataLa PlataArgentina
| | - Vanesa Soledad Marin Viegas
- Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA)Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)Departamento de Ciencias BiológicasFacultad de Ciencias ExactasUniversidad Nacional de La PlataLa PlataArgentina
| | - Silvina Mangano
- Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA)Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)Departamento de Ciencias BiológicasFacultad de Ciencias ExactasUniversidad Nacional de La PlataLa PlataArgentina
- Present address: Fundación Instituto LeloirAv. Patricias Argentinas 435Buenos AiresArgentina
| | - Andreas Loos
- Department of Applied Genetics and Cell BiologyUniversity of Natural Resources and Life SciencesViennaAustria
- Present address: Aridis Pharmaceuticals Inc.5941 Optical CourtSan JoseCA95138USA
| | - Herta Steinkellner
- Department of Applied Genetics and Cell BiologyUniversity of Natural Resources and Life SciencesViennaAustria
| | - Silvana Petruccelli
- Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA)Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)Departamento de Ciencias BiológicasFacultad de Ciencias ExactasUniversidad Nacional de La PlataLa PlataArgentina
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26
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Robinson DG, Neuhaus JM. Receptor-mediated sorting of soluble vacuolar proteins: myths, facts, and a new model. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:4435-49. [PMID: 27262127 DOI: 10.1093/jxb/erw222] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
To prevent their being released to the cell exterior, acid hydrolases are recognized by receptors at some point in the secretory pathway and diverted towards the lytic compartment of the cell (lysosome or vacuole). In animal cells, the receptor is called the mannosyl 6-phosphate receptor (MPR) and it binds hydrolase ligands in the trans-Golgi network (TGN). These ligands are then sequestered into clathrin-coated vesicles (CCVs) because of motifs in the cytosolic tail of the MPR which interact first with monomeric adaptors (Golgi-localized, Gamma-ear-containing, ARF-binding proteins, GGAs) and then with tetrameric (adaptin) adaptor complexes. The CCVs then fuse with an early endosome, whose more acidic lumen causes the ligands to dissociate. The MPRs are then recycled back to the TGN via retromer-coated carriers. Plants have vacuolar sorting receptors (VSRs) which were originally identified in CCVs isolated from pea (Pisum sativum L.) cotyledons. It was therefore assumed that VSRs would have an analogous function in plants to MPRs in animals. Although this dogma has enjoyed wide support over the last 20 years there are many inconsistencies. Recently, results have been published which are quite contrary to it. It now emerges that VSRs and their ligands can interact very early in the secretory pathway, and dissociate in the TGN, which, in contrast to its mammalian counterpart, has a pH of 5.5. Multivesicular endosomes in plants lack proton pump complexes and consequently have an almost neutral internal pH, which discounts them as organelles of pH-dependent receptor-ligand dissociation. These data force a critical re-evaluation of the role of CCVs at the TGN, especially considering that vacuolar cargo ligands have never been identified in them. We propose that one population of TGN-derived CCVs participate in retrograde transport of VSRs from the TGN. We also present a new model to explain how secretory and vacuolar cargo proteins are effectively separated after entering the late Golgi/TGN compartments.
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Affiliation(s)
- David G Robinson
- Centre for Organismal Studies (COS), University of Heidelberg, Germany
| | - Jean-Marc Neuhaus
- Institute of Biology, Laboratory of Cell and Molecular Biology, University of Neuchatel, Switzerland
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de Marcos Lousa C, Denecke J. Lysosomal and vacuolar sorting: not so different after all! Biochem Soc Trans 2016; 44:891-7. [PMID: 27284057 PMCID: PMC5264500 DOI: 10.1042/bst20160050] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Indexed: 12/12/2022]
Abstract
Soluble hydrolases represent the main proteins of lysosomes and vacuoles and are essential to sustain the lytic properties of these organelles typical for the eukaryotic organisms. The sorting of these proteins from ER residents and secreted proteins is controlled by highly specific receptors to avoid mislocalization and subsequent cellular damage. After binding their soluble cargo in the early stage of the secretory pathway, receptors rely on their own sorting signals to reach their target organelles for ligand delivery, and to recycle back for a new round of cargo recognition. Although signals in cargo and receptor molecules have been studied in human, yeast and plant model systems, common denominators and specific examples of diversification have not been systematically explored. This review aims to fill this niche by comparing the structure and the function of lysosomal/vacuolar sorting receptors (VSRs) from these three organisms.
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Affiliation(s)
- Carine de Marcos Lousa
- School of Clinical and Applied Sciences, Faculty of Biomedical Sciences, Leeds Beckett University, Leeds LS13HE, U.K. Centre for Plant Sciences, University of Leeds, Leeds LS29JT, U.K.
| | - Jurgen Denecke
- Centre for Plant Sciences, University of Leeds, Leeds LS29JT, U.K.
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Cui Y, Shen J, Gao C, Zhuang X, Wang J, Jiang L. Biogenesis of Plant Prevacuolar Multivesicular Bodies. MOLECULAR PLANT 2016; 9:774-86. [PMID: 26836198 DOI: 10.1016/j.molp.2016.01.011] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 01/04/2016] [Accepted: 01/26/2016] [Indexed: 05/20/2023]
Abstract
Plant prevacuolar compartments (PVCs), or multivesicular bodies (MVBs), are single membrane-bound organelles that play important roles in mediating protein trafficking to vacuoles in the secretory pathway. PVC/MVB also serves as a late endosome in the endocytic pathway in plants. Since the plant PVC was identified as an MVB more than 10 years ago, great progress has been made toward the understanding of PVC/MVB function and biogenesis in plants. In this review, we first summarize previous research into the identification and characterization of plant PVCs/MVBs, and then highlight recent advances on the mechanisms underlying intraluminal vesicle formation and maturation of plant PVCs/MVBs. In addition, we discuss the possible crosstalk that appears to occur between PVCs/MVBs and autophagosomes during autophagy in plants. Finally, we list some open questions and present future perspectives in this field.
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Affiliation(s)
- Yong Cui
- State Key Laboratory of Agrobiotechnology, Centre for Cell & Developmental Biology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Jinbo Shen
- State Key Laboratory of Agrobiotechnology, Centre for Cell & Developmental Biology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Caiji Gao
- State Key Laboratory of Agrobiotechnology, Centre for Cell & Developmental Biology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Xiaohong Zhuang
- State Key Laboratory of Agrobiotechnology, Centre for Cell & Developmental Biology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Junqi Wang
- State Key Laboratory of Agrobiotechnology, Centre for Cell & Developmental Biology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China; Shenzhen Key Laboratory of Cell Microenvironment, Department of Biology, South University of Science and Technology of China, Shenzhen 518055, China
| | - Liwen Jiang
- State Key Laboratory of Agrobiotechnology, Centre for Cell & Developmental Biology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China; CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen 518057, China.
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Kim SJ, Brandizzi F. The plant secretory pathway for the trafficking of cell wall polysaccharides and glycoproteins. Glycobiology 2016; 26:940-949. [PMID: 27072815 DOI: 10.1093/glycob/cww044] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 04/03/2016] [Indexed: 01/22/2023] Open
Abstract
Plant endomembranes are required for the biosynthesis and secretion of complex cell wall matrix polysaccharides, glycoproteins and proteoglycans. To define the biochemical roadmap that guides the synthesis and deposition of these cell wall components it is first necessary to outline the localization of the biosynthetic and modifying enzymes involved, as well as the distribution of the intermediate and final constituents of the cell wall. Thus far, a comprehensive understanding of cell wall matrix components has been hampered by the multiplicity of trafficking routes in the secretory pathway, and the diverse biosynthetic roles of the endomembrane organelles, which may exhibit tissue and development specific features. However, the recent identification of protein complexes producing matrix polysaccharides, and those supporting the synthesis and distribution of a grass-specific hemicellulose are advancing our understanding of the functional contribution of the plant secretory pathway in cell wall biosynthesis. In this review, we provide an overview of the plant membrane trafficking routes and report on recent exciting accomplishments in the understanding of the mechanisms underlying secretion with focus on cell wall synthesis in plants.
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Affiliation(s)
- Sang-Jin Kim
- Great Lakes Bioenergy Research Center Michigan State University-DOE Plant Research Laboratory
| | - Federica Brandizzi
- Great Lakes Bioenergy Research Center Michigan State University-DOE Plant Research Laboratory Department of Plant Biology, Michigan State University, East Lansing, MI, USA
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30
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Künzl F, Früholz S, Fäßler F, Li B, Pimpl P. Receptor-mediated sorting of soluble vacuolar proteins ends at the trans-Golgi network/early endosome. NATURE PLANTS 2016; 2:16017. [PMID: 27249560 DOI: 10.1038/nplants.2016.17] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 02/01/2016] [Indexed: 05/03/2023]
Abstract
The sorting of soluble proteins for degradation in the vacuole is of vital importance in plant cells, and relies on the activity of vacuolar sorting receptors (VSRs). In the plant endomembrane system, VSRs bind vacuole-targeted proteins and facilitate their transport to the vacuole. Where exactly these interactions take place has remained controversial, however. Here, we examine the potential for VSR-ligand interactions in all compartments of the vacuolar transport system in tobacco mesophyll protoplasts. To do this, we developed compartment-specific VSR sensors that assemble as a result of a nanobody-epitope interaction, and monitored the degree of ligand binding by analysing Förster resonance energy transfer using fluorescence lifetime imaging microscopy (FRET-FLIM). We show that VSRs bind ligands in the endoplasmic reticulum (ER) and in the Golgi, but not in the trans-Golgi network/early endosome (TGN/EE) or multivesicular late endosomes, suggesting that the post-TGN/EE trafficking of ligands towards the vacuole is VSR independent. We verify this by showing that non-VSR-ligands are also delivered to the vacuole from the TGN/EE after endocytic uptake. We conclude that VSRs are required for the transport of ligands from the ER and the Golgi to the TGN/EE, and suggest that the onward transport to the vacuole occurs by default.
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Affiliation(s)
- Fabian Künzl
- Centre for Plant Molecular Biology (ZMBP), University of Tübingen, Auf der Morgenstelle 32, D-72076 Tübingen, Germany
| | - Simone Früholz
- Centre for Plant Molecular Biology (ZMBP), University of Tübingen, Auf der Morgenstelle 32, D-72076 Tübingen, Germany
| | - Florian Fäßler
- Centre for Plant Molecular Biology (ZMBP), University of Tübingen, Auf der Morgenstelle 32, D-72076 Tübingen, Germany
| | - Beibei Li
- Centre for Plant Molecular Biology (ZMBP), University of Tübingen, Auf der Morgenstelle 32, D-72076 Tübingen, Germany
| | - Peter Pimpl
- Centre for Plant Molecular Biology (ZMBP), University of Tübingen, Auf der Morgenstelle 32, D-72076 Tübingen, Germany
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Wang ZY, Gehring C, Zhu J, Li FM, Zhu JK, Xiong L. The Arabidopsis Vacuolar Sorting Receptor1 is required for osmotic stress-induced abscisic acid biosynthesis. PLANT PHYSIOLOGY 2015; 167:137-52. [PMID: 25416474 PMCID: PMC4281004 DOI: 10.1104/pp.114.249268] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Osmotic stress activates the biosynthesis of the phytohormone abscisic acid (ABA) through a pathway that is rate limited by the carotenoid cleavage enzyme 9-cis-epoxycarotenoid dioxygenase (NCED). To understand the signal transduction mechanism underlying the activation of ABA biosynthesis, we performed a forward genetic screen to isolate mutants defective in osmotic stress regulation of the NCED3 gene. Here, we identified the Arabidopsis (Arabidopsis thaliana) Vacuolar Sorting Receptor1 (VSR1) as a unique regulator of ABA biosynthesis. The vsr1 mutant not only shows increased sensitivity to osmotic stress, but also is defective in the feedback regulation of ABA biosynthesis by ABA. Further analysis revealed that vacuolar trafficking mediated by VSR1 is required for osmotic stress-responsive ABA biosynthesis and osmotic stress tolerance. Moreover, under osmotic stress conditions, the membrane potential, calcium flux, and vacuolar pH changes in the vsr1 mutant differ from those in the wild type. Given that manipulation of the intracellular pH is sufficient to modulate the expression of ABA biosynthesis genes, including NCED3, and ABA accumulation, we propose that intracellular pH changes caused by osmotic stress may play a signaling role in regulating ABA biosynthesis and that this regulation is dependent on functional VSR1.
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Affiliation(s)
- Zhen-Yu Wang
- Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia (Z.-Y.W., C.G., L.X.);State Key Laboratory of Grassland Agroecosystem, Institute of Arid Agroecology, School of Life Sciences, Lanzhou University, Lanzhou 730000, Gansu Province, China (Z.-Y.W., F.-M.L.);Department of Plant Science and Landscape Architecture, University of Maryland, College Park, Maryland 20742 (J.Z.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907 (J.-K.Z.); andShanghai Center for Plant Stress Biology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (J.-K.Z.)
| | - Chris Gehring
- Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia (Z.-Y.W., C.G., L.X.);State Key Laboratory of Grassland Agroecosystem, Institute of Arid Agroecology, School of Life Sciences, Lanzhou University, Lanzhou 730000, Gansu Province, China (Z.-Y.W., F.-M.L.);Department of Plant Science and Landscape Architecture, University of Maryland, College Park, Maryland 20742 (J.Z.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907 (J.-K.Z.); andShanghai Center for Plant Stress Biology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (J.-K.Z.)
| | - Jianhua Zhu
- Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia (Z.-Y.W., C.G., L.X.);State Key Laboratory of Grassland Agroecosystem, Institute of Arid Agroecology, School of Life Sciences, Lanzhou University, Lanzhou 730000, Gansu Province, China (Z.-Y.W., F.-M.L.);Department of Plant Science and Landscape Architecture, University of Maryland, College Park, Maryland 20742 (J.Z.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907 (J.-K.Z.); andShanghai Center for Plant Stress Biology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (J.-K.Z.)
| | - Feng-Min Li
- Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia (Z.-Y.W., C.G., L.X.);State Key Laboratory of Grassland Agroecosystem, Institute of Arid Agroecology, School of Life Sciences, Lanzhou University, Lanzhou 730000, Gansu Province, China (Z.-Y.W., F.-M.L.);Department of Plant Science and Landscape Architecture, University of Maryland, College Park, Maryland 20742 (J.Z.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907 (J.-K.Z.); andShanghai Center for Plant Stress Biology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (J.-K.Z.)
| | - Jian-Kang Zhu
- Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia (Z.-Y.W., C.G., L.X.);State Key Laboratory of Grassland Agroecosystem, Institute of Arid Agroecology, School of Life Sciences, Lanzhou University, Lanzhou 730000, Gansu Province, China (Z.-Y.W., F.-M.L.);Department of Plant Science and Landscape Architecture, University of Maryland, College Park, Maryland 20742 (J.Z.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907 (J.-K.Z.); andShanghai Center for Plant Stress Biology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (J.-K.Z.)
| | - Liming Xiong
- Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia (Z.-Y.W., C.G., L.X.);State Key Laboratory of Grassland Agroecosystem, Institute of Arid Agroecology, School of Life Sciences, Lanzhou University, Lanzhou 730000, Gansu Province, China (Z.-Y.W., F.-M.L.);Department of Plant Science and Landscape Architecture, University of Maryland, College Park, Maryland 20742 (J.Z.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907 (J.-K.Z.); andShanghai Center for Plant Stress Biology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (J.-K.Z.)
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Shen J, Ding Y, Gao C, Rojo E, Jiang L. N-linked glycosylation of AtVSR1 is important for vacuolar protein sorting in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 80:977-92. [PMID: 25293377 DOI: 10.1111/tpj.12696] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 09/25/2014] [Accepted: 09/25/2014] [Indexed: 05/18/2023]
Abstract
Vacuolar sorting receptors (VSRs) in Arabidopsis mediate the sorting of soluble proteins to vacuoles in the secretory pathway. The VSRs are post-translationally modified by the attachment of N-glycans, but the functional significance of such a modification remains unknown. Here we have studied the role(s) of glycosylation in the stability, trafficking and vacuolar protein transport of AtVSR1 in Arabidopsis protoplasts. AtVSR1 harbors three complex-type N-glycans, which are located in the N-terminal 'PA domain', the central region and the C-terminal epidermal growth factor repeat domain, respectively. We have demonstrated that: (i) the N-glycans do not affect the targeting of AtVSR1 to pre-vacuolar compartments (PVCs) and its vacuolar degradation; and (ii) N-glycosylation alters the binding affinity of AtVSR1 to cargo proteins and affects the transport of cargo into the vacuole. Hence, N-glycosylation of AtVSR1 plays a critical role in its function as a VSR in plants.
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Affiliation(s)
- Jinbo Shen
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong, China
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33
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Kang H, Hwang I. Vacuolar Sorting Receptor-Mediated Trafficking of Soluble Vacuolar Proteins in Plant Cells. PLANTS 2014; 3:392-408. [PMID: 27135510 PMCID: PMC4844349 DOI: 10.3390/plants3030392] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 08/18/2014] [Accepted: 08/18/2014] [Indexed: 01/13/2023]
Abstract
Vacuoles are one of the most prominent organelles in plant cells, and they play various important roles, such as degradation of waste materials, storage of ions and metabolites, and maintaining turgor. During the past two decades, numerous advances have been made in understanding how proteins are specifically delivered to the vacuole. One of the most crucial steps in this process is specific sorting of soluble vacuolar proteins. Vacuolar sorting receptors (VSRs), which are type I membrane proteins, are involved in the sorting and packaging of soluble vacuolar proteins into transport vesicles with the help of various accessory proteins. To date, large amounts of data have led to the development of two different models describing VSR-mediated vacuolar trafficking that are radically different in multiple ways, particularly regarding the location of cargo binding to, and release from, the VSR and the types of carriers utilized. In this review, we summarize current literature aimed at elucidating VSR-mediated vacuolar trafficking and compare the two models with respect to the sorting signals of vacuolar proteins, as well as the molecular machinery involved in VSR-mediated vacuolar trafficking and its action mechanisms.
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Affiliation(s)
- Hyangju Kang
- Department of Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Inhwan Hwang
- Department of Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea.
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea.
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Polarization of IRON-REGULATED TRANSPORTER 1 (IRT1) to the plant-soil interface plays crucial role in metal homeostasis. Proc Natl Acad Sci U S A 2014; 111:8293-8. [PMID: 24843126 DOI: 10.1073/pnas.1402262111] [Citation(s) in RCA: 179] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
In plants, the controlled absorption of soil nutrients by root epidermal cells is critical for growth and development. IRON-REGULATED TRANSPORTER 1 (IRT1) is the main root transporter taking up iron from the soil and is also the main entry route in plants for potentially toxic metals such as manganese, zinc, cobalt, and cadmium. Previous work demonstrated that the IRT1 protein localizes to early endosomes/trans-Golgi network (EE/TGN) and is constitutively endocytosed through a monoubiquitin- and clathrin-dependent mechanism. Here, we show that the availability of secondary non-iron metal substrates of IRT1 (Zn, Mn, and Co) controls the localization of IRT1 between the outer polar domain of the plasma membrane and EE/TGN in root epidermal cells. We also identify FYVE1, a phosphatidylinositol-3-phosphate-binding protein recruited to late endosomes, as an important regulator of IRT1-dependent metal transport and metal homeostasis in plants. FYVE1 controls IRT1 recycling to the plasma membrane and impacts the polar delivery of this transporter to the outer plasma membrane domain. This work establishes a functional link between the dynamics and the lateral polarity of IRT1 and the transport of its substrates, and identifies a molecular mechanism driving polar localization of a cell surface protein in plants.
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35
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Isayenkov SV. Plant vacuoles: Physiological roles and mechanisms of vacuolar sorting and vesicular trafficking. CYTOL GENET+ 2014. [DOI: 10.3103/s0095452714020042] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Robinson DG, Pimpl P. Clathrin and post-Golgi trafficking: a very complicated issue. TRENDS IN PLANT SCIENCE 2014; 19:134-9. [PMID: 24263003 DOI: 10.1016/j.tplants.2013.10.008] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 10/18/2013] [Accepted: 10/21/2013] [Indexed: 05/21/2023]
Abstract
Clathrin-coated vesicles (CCVs) are formed at the plasma membrane and act as vectors for endocytosis. They also assemble at the trans-Golgi network (TGN), but their exact function at this organelle is unclear. Recent studies have examined the effects on vacuolar and secretory protein transport of knockout mutations of the adaptor protein 1 (AP1) μ-adaptin subunit AP1M, but these investigations do not clarify the situation. These mutations lead to the abrogation of multiple trafficking pathways at the TGN and cannot be used as evidence in favour of CCVs being agents for receptor-mediated export of vacuolar proteins out of the TGN. This transport process could just as easily occur through the maturation of the TGN into intermediate compartments that subsequently fuse with the vacuole.
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Affiliation(s)
- David G Robinson
- Centre for Organismal Studies (COS), University of Heidelberg, Heidelberg, Germany.
| | - Peter Pimpl
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, Germany
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Gershlick DC, de Marcos Lousa C, Foresti O, Lee AJ, Pereira EA, daSilva LL, Bottanelli F, Denecke J. Golgi-dependent transport of vacuolar sorting receptors is regulated by COPII, AP1, and AP4 protein complexes in tobacco. THE PLANT CELL 2014; 26:1308-29. [PMID: 24642936 PMCID: PMC4001386 DOI: 10.1105/tpc.113.122226] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 02/10/2014] [Accepted: 02/18/2014] [Indexed: 05/02/2023]
Abstract
The cycling of vacuolar sorting receptors (VSRs) between early and late secretory pathway compartments is regulated by signals in the cytosolic tail, but the exact pathway is controversial. Here, we show that receptor targeting in tobacco (Nicotiana tabacum) initially involves a canonical coat protein complex II-dependent endoplasmic reticulum-to-Golgi bulk flow route and that VSR-ligand interactions in the cis-Golgi play an important role in vacuolar sorting. We also show that a conserved Glu is required but not sufficient for rate-limiting YXX-mediated receptor trafficking. Protein-protein interaction studies show that the VSR tail interacts with the μ-subunits of plant or mammalian clathrin adaptor complex AP1 and plant AP4 but not that of plant and mammalian AP2. Mutants causing a detour of full-length receptors via the cell surface invariantly cause the secretion of VSR ligands. Therefore, we propose that cycling via the plasma membrane is unlikely to play a role in biosynthetic vacuolar sorting under normal physiological conditions and that the conserved Ile-Met motif is mainly used to recover mistargeted receptors. This occurs via a fundamentally different pathway from the prevacuolar compartment that does not mediate recycling. The role of clathrin and clathrin-independent pathways in vacuolar targeting is discussed.
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Affiliation(s)
- David C. Gershlick
- Centre for Plant Sciences, School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Carine de Marcos Lousa
- Centre for Plant Sciences, School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | | | - Andrew J. Lee
- Centre for Plant Sciences, School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | | | | | | | - Jurgen Denecke
- Centre for Plant Sciences, School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
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Groen AJ, Sancho-Andrés G, Breckels LM, Gatto L, Aniento F, Lilley KS. Identification of trans-golgi network proteins in Arabidopsis thaliana root tissue. J Proteome Res 2014; 13:763-76. [PMID: 24344820 PMCID: PMC3929368 DOI: 10.1021/pr4008464] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
![]()
Knowledge of protein
subcellular localization assists in the elucidation
of protein function and understanding of different biological mechanisms
that occur at discrete subcellular niches. Organelle-centric proteomics
enables localization of thousands of proteins simultaneously. Although
such techniques have successfully allowed organelle protein catalogues
to be achieved, they rely on the purification or significant enrichment
of the organelle of interest, which is not achievable for many organelles.
Incomplete separation of organelles leads to false discoveries, with
erroneous assignments. Proteomics methods that measure the distribution
patterns of specific organelle markers along density gradients are
able to assign proteins of unknown localization based on comigration
with known organelle markers, without the need for organelle purification.
These methods are greatly enhanced when coupled to sophisticated computational
tools. Here we apply and compare multiple approaches to establish
a high-confidence data set of Arabidopsis root tissue
trans-Golgi network (TGN) proteins. The method employed involves immunoisolations
of the TGN, coupled to probability-based organelle proteomics techniques.
Specifically, the technique known as LOPIT (localization of organelle
protein by isotope tagging), couples density centrifugation with quantitative
mass-spectometry-based proteomics using isobaric labeling and targeted
methods with semisupervised machine learning methods. We demonstrate
that while the immunoisolation method gives rise to a significant
data set, the approach is unable to distinguish cargo proteins and
persistent contaminants from full-time residents of the TGN. The LOPIT
approach, however, returns information about many subcellular niches
simultaneously and the steady-state location of proteins. Importantly,
therefore, it is able to dissect proteins present in more than one
organelle and cargo proteins en route to other cellular destinations
from proteins whose steady-state location favors the TGN. Using this
approach, we present a robust list of Arabidopsis TGN proteins.
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Affiliation(s)
- Arnoud J Groen
- Cambridge Centre for Proteomics, Cambridge Systems Biology Centre, Department of Biochemistry, University of Cambridge , 80 Tennis Court Road, Cambridge CB2 1GA, United Kingdom
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Robinson DG, Pimpl P. Receptor-mediated transport of vacuolar proteins: a critical analysis and a new model. PROTOPLASMA 2014; 251:247-64. [PMID: 24019013 DOI: 10.1007/s00709-013-0542-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Accepted: 08/20/2013] [Indexed: 05/20/2023]
Abstract
In this article we challenge the widely accepted view that receptors for soluble vacuolar proteins (VSRs) bind to their ligands at the trans-Golgi network (TGN) and transport this cargo via clathrin-coated vesicles (CCV) to a multivesicular prevacuolar compartment. This notion, which we term the "classical model" for vacuolar protein sorting, further assumes that low pH in the prevacuolar compartment causes VSR-ligand dissociation, resulting in a retromer-mediated retrieval of the VSRs to the TGN. We have carefully evaluated the literature with respect to morphology and function of the compartments involved, localization of key components of the sorting machinery, and conclude that there is little direct evidence in its favour. Firstly, unlike mammalian cells where the sorting receptor for lysosomal hydrolases recognizes its ligand in the TGN, the available data suggests that in plants VSRs interact with vacuolar cargo ligands already in the endoplasmic reticulum. Secondly, the evidence supporting the packaging of VSR-ligand complexes into CCV at the TGN is not conclusive. Thirdly, the prevacuolar compartment appears to have a pH unsuitable for VSR-ligand dissociation and lacks the retromer core and the sorting nexins needed for VSR recycling. We present an alternative model for protein sorting in the TGN that draws attention to the much overlooked role of Ca(2+) in VSR-ligand interactions and which may possibly also be a factor in the sequestration of secretory proteins.
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Affiliation(s)
- David G Robinson
- Centre for Organismal Studies (COS), University of Heidelberg, Heidelberg, Germany
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Shen J, Zeng Y, Zhuang X, Sun L, Yao X, Pimpl P, Jiang L. Organelle pH in the Arabidopsis endomembrane system. MOLECULAR PLANT 2013; 6:1419-37. [PMID: 23702593 DOI: 10.1093/mp/sst079] [Citation(s) in RCA: 226] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The pH of intracellular compartments is essential for the viability of cells. Despite its relevance, little is known about the pH of these compartments. To measure pH in vivo, we have first generated two pH sensors by combining the improved-solubility feature of solubility-modified green fluorescent protein (GFP) (smGFP) with the pH-sensing capability of the pHluorins and codon optimized for expression in Arabidopsis. PEpHluorin (plant-solubility-modified ecliptic pHluorin) gradually loses fluorescence as pH is lowered with fluorescence vanishing at pH 6.2 and PRpHluorin (plant-solubility-modified ratiomatric pHluorin), a dual-excitation sensor, allowing for precise measurements. Compartment-specific sensors were generated by further fusing specific sorting signals to PEpHluorin and PRpHluorin. Our results show that the pH of cytosol and nucleus is similar (pH 7.3 and 7.2), while peroxisomes, mitochondrial matrix, and plastidial stroma have alkaline pH. Compartments of the secretory pathway reveal a gradual acidification, spanning from pH 7.1 in the endoplasmic reticulum (ER) to pH 5.2 in the vacuole. Surprisingly, pH in the trans-Golgi network (TGN) and multivesicular body (MVB) is, with pH 6.3 and 6.2, quite similar. The inhibition of vacuolar-type H(+)-ATPase (V-ATPase) with concanamycin A (ConcA) caused drastic increase in pH in TGN and vacuole. Overall, the PEpHluorin and PRpHluorin are excellent pH sensors for visualization and quantification of pH in vivo, respectively.
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Affiliation(s)
- Jinbo Shen
- School of Life Sciences, Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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Shen J, Suen PK, Wang X, Lin Y, Lo SW, Rojo E, Jiang L. An in vivo expression system for the identification of cargo proteins of vacuolar sorting receptors in Arabidopsis culture cells. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 75:1003-17. [PMID: 23738689 DOI: 10.1111/tpj.12257] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2013] [Revised: 05/27/2013] [Accepted: 06/04/2013] [Indexed: 05/18/2023]
Abstract
Vacuolar sorting receptors (VSRs) are type I integral membrane family proteins that in plant cells are thought to recognize cargo proteins at the late Golgi or trans-Golgi network (TGN) for vacuolar transport via the pre-vacuolar compartment (PVC). However, little is known about VSR cargo proteins in plants. Here we developed and tested an in vivo expression system for the identification of VSR cargos which is based on the premise that the expressed N-terminus of VSRs will be secreted into the culture medium along with their corresponding cargo proteins. Indeed, transgenic Arabidopsis culture cell lines expressing VSR N-terminal binding domains (VSRNTs) were shown to secrete truncated VSRs (BP80NT, AtVSR1NT and AtVSR4NT) with attached cargo molecules into the culture medium. Putative cargo proteins were identified through mass spectrometry. Several identified cargo proteins were confirmed by localization studies and interaction analysis with VSRs. The screening strategy described here should be applicable to all VSRs and will help identify and study cargo proteins for individual VSR proteins. This method should be useful for both cargo identification and protein-protein interaction in vivo.
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Affiliation(s)
- Jinbo Shen
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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De Marchis F, Bellucci M, Pompa A. Unconventional pathways of secretory plant proteins from the endoplasmic reticulum to the vacuole bypassing the Golgi complex. PLANT SIGNALING & BEHAVIOR 2013; 8:25129. [PMID: 23733072 PMCID: PMC3999078 DOI: 10.4161/psb.25129] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Studies on the basic mechanisms that regulate vacuolar delivering of proteins synthesized in the endoplasmic reticulum (ER) have a great importance in plant cell biology. Indeed, many aspects of plant physiology are affected by this intracellular traffic, for example, germination or reaction to biotic stresses due to the accumulation of storage proteins in seeds or enzymes in vegetative tissues, respectively. Up to now, the Golgi complex has been considered the main hub in the sorting of vacuolar secretory proteins; those polypeptides able to reach their final destination without the aid of this organelle are regarded as exceptions to an established route. This mini-review aims to emphasize the existence of several Golgi-independent pathways involved in the trafficking of different types of vacuolar proteins.
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Arabidopsis μ-adaptin subunit AP1M of adaptor protein complex 1 mediates late secretory and vacuolar traffic and is required for growth. Proc Natl Acad Sci U S A 2013; 110:10318-23. [PMID: 23733933 DOI: 10.1073/pnas.1300460110] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Adaptor protein (AP) complexes are the predominant coat proteins of membrane vesicles in post-Golgi trafficking of mammalian cells. Each AP complex contains a specific medium subunit, μ-adaptin, that selects cargo proteins bearing sequence-specific sorting motifs. Much less is known about the AP complexes and their μ subunits in plants. Because of uncertain homology, the μ-adaptins of Arabidopsis have been designated muA through muD [Happel et al. (2004) Plant J 37(5):678-693]. Furthermore, only muD has been assigned to a specific AP complex, AP-3, involved in Golgi-vacuolar trafficking [Niihama et al. (2009) Plant Cell Physiol 50(12):2057-2068, Zwiewka et al. (2011) Cell Res 21(12):1711-1722, and Wolfenstetter et al. (2012) Plant Cell 24(1):215-232]. In contrast, the μ subunit of neither the post-Golgi trafficking AP-1 complex nor the endocytic AP-2 complex has been identified. Here, we report the functional analysis of redundant AP-1 μ-adaptins AP1M1 (also known as muB1) and AP1M2 (also known as muB2). Coimmunoprecipitation revealed that both AP1M2 and its less strongly expressed isoform AP1M1 are complexed with the large subunit γ-adaptin of AP-1. In addition, AP1M2 was localized at or near the trans-Golgi network. Knockout mutations of AP1M2 impaired pollen function and arrested plant growth whereas the ap1m1 ap1m2 double mutant was nearly pollen-lethal. At the cellular level, the absence of AP1M2 entailed inhibition of multiple trafficking pathways from the trans-Golgi network to the vacuole and to the plasma membrane in interphase and to the plane of cell division in cytokinesis. Thus, AP-1 is crucial in post-Golgi trafficking in plant cells and required for cell division and plant growth.
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Xiang L, Etxeberria E, den Ende W. Vacuolar protein sorting mechanisms in plants. FEBS J 2013; 280:979-93. [DOI: 10.1111/febs.12092] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Revised: 11/08/2012] [Accepted: 12/11/2012] [Indexed: 01/12/2023]
Affiliation(s)
- Li Xiang
- Laboratory of Molecular Plant Biology KU Leuven Belgium
| | - Ed Etxeberria
- Horticulture Department Citrus Research and Education Center University of Florida Lake Alfred FL USA
| | - Wim den Ende
- Laboratory of Molecular Plant Biology KU Leuven Belgium
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Seidel T, Siek M, Marg B, Dietz KJ. Energization of vacuolar transport in plant cells and its significance under stress. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 304:57-131. [PMID: 23809435 DOI: 10.1016/b978-0-12-407696-9.00002-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The plant vacuole is of prime importance in buffering environmental perturbations and in coping with abiotic stress caused by, for example, drought, salinity, cold, or UV. The large volume, the efficient integration in anterograde and retrograde vesicular trafficking, and the dynamic equipment with tonoplast transporters enable the vacuole to fulfill indispensible functions in cell biology, for example, transient and permanent storage, detoxification, recycling, pH and redox homeostasis, cell expansion, biotic defence, and cell death. This review first focuses on endomembrane dynamics and then summarizes the functions, assembly, and regulation of secretory and vacuolar proton pumps: (i) the vacuolar H(+)-ATPase (V-ATPase) which represents a multimeric complex of approximately 800 kDa, (ii) the vacuolar H(+)-pyrophosphatase, and (iii) the plasma membrane H(+)-ATPase. These primary proton pumps regulate the cytosolic pH and provide the driving force for secondary active transport. Carriers and ion channels modulate the proton motif force and catalyze uptake and vacuolar compartmentation of solutes and deposition of xenobiotics or secondary compounds such as flavonoids. ABC-type transporters directly energized by MgATP complement the transport portfolio that realizes the multiple functions in stress tolerance of plants.
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Affiliation(s)
- Thorsten Seidel
- Biochemistry and Physiology of Plants, Faculty of Biology, Bielefeld University, Bielefeld, Germany.
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Lee Y, Jang M, Song K, Kang H, Lee MH, Lee DW, Zouhar J, Rojo E, Sohn EJ, Hwang I. Functional identification of sorting receptors involved in trafficking of soluble lytic vacuolar proteins in vegetative cells of Arabidopsis. PLANT PHYSIOLOGY 2013; 161:121-33. [PMID: 23175753 PMCID: PMC3532246 DOI: 10.1104/pp.112.210914] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
In eukaryotic cells, protein trafficking plays an essential role in biogenesis of proteins that belong to the endomembrane compartments. In this process, an important step is the sorting of organellar proteins depending on their final destinations. For vacuolar proteins, vacuolar sorting receptors (VSRs) and receptor homology-transmembrane-RING H2 domain proteins (RMRs) are thought to be responsible. Arabidopsis (Arabidopsis thaliana) contains seven VSRs. Among them, VSR1, VSR3, and VSR4 are involved in sorting storage proteins targeted to the protein storage vacuole (PSV) in seeds. However, the identity of VSRs for soluble proteins of the lytic vacuole in vegetative cells remains controversial. Here, we provide evidence that VSR1, VSR3, and VSR4 are involved in sorting soluble lytic vacuolar and PSV proteins in vegetative cells. In protoplasts from leaf tissues of vsr1vsr3 and vsr1vsr4 but not vsr5vsr6, and rmr1rmr2 and rmr3rmr4 double mutants, soluble lytic vacuolar (Arabidopsis aleurain-like protein:green fluorescent protein [GFP] and carboxypeptidase Y:GFP and PSV (phaseolin) proteins, but not the vacuolar membrane protein Arabidopsis βFructosidase4:GFP, exhibited defects in their trafficking; they accumulated to the endoplasmic reticulum with an increased secretion into medium. The trafficking defects in vsr1vsr4 protoplasts were rescued by VSR1 or VSR4 but not VSR5 or AtRMR1. Furthermore, of the luminal domain swapping mutants between VSR1 and VSR5, the mutant with the luminal domain of VSR1, but not that of VSR5, rescued the trafficking defects of Arabidopsis aleurain-like protein:GFP and phaseolin in vsr1vsr4 protoplasts. Based on these results, we propose that VSR1, VSR3, and VSR4, but not other VSRs, are involved in sorting soluble lytic vacuolar and PSV proteins for their trafficking to the vacuoles in vegetative cells.
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Kang H, Kim SY, Song K, Sohn EJ, Lee Y, Lee DW, Hara-Nishimura I, Hwang I. Trafficking of vacuolar proteins: the crucial role of Arabidopsis vacuolar protein sorting 29 in recycling vacuolar sorting receptor. THE PLANT CELL 2012; 24:5058-73. [PMID: 23263768 PMCID: PMC3556975 DOI: 10.1105/tpc.112.103481] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 11/26/2012] [Accepted: 12/06/2012] [Indexed: 05/18/2023]
Abstract
The retromer is involved in recycling lysosomal sorting receptors in mammals. A component of the retromer complex in Arabidopsis thaliana, vacuolar protein sorting 29 (VPS29), plays a crucial role in trafficking storage proteins to protein storage vacuoles. However, it is not known whether or how vacuolar sorting receptors (VSRs) are recycled from the prevacuolar compartment (PVC) to the trans-Golgi network (TGN) during trafficking to the lytic vacuole (LV). Here, we report that VPS29 plays an essential role in the trafficking of soluble proteins to the LV from the TGN to the PVC. maigo1-1 (mag1-1) mutants, which harbor a knockdown mutation in VPS29, were defective in trafficking of two soluble proteins, Arabidopsis aleurain-like protein (AALP):green fluorescent protein (GFP) and sporamin:GFP, to the LV but not in trafficking membrane proteins to the LV or plasma membrane or via the secretory pathway. AALP:GFP and sporamin:GFP in mag1-1 protoplasts accumulated in the TGN but were also secreted into the medium. In mag1-1 mutants, VSR1 failed to recycle from the PVC to the TGN; rather, a significant proportion was transported to the LV; VSR1 overexpression rescued this defect. Moreover, endogenous VSRs were expressed at higher levels in mag1-1 plants. Based on these results, we propose that VPS29 plays a crucial role in recycling VSRs from the PVC to the TGN during the trafficking of soluble proteins to the LV.
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Affiliation(s)
- Hyangju Kang
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Soo Youn Kim
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Kyungyoung Song
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Eun Ju Sohn
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Yongjik Lee
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Dong Wook Lee
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Ikuko Hara-Nishimura
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan
| | - Inhwan Hwang
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea
- Address correspondence to
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Robinson DG, Pimpl P, Scheuring D, Stierhof YD, Sturm S, Viotti C. Trying to make sense of retromer. TRENDS IN PLANT SCIENCE 2012; 17:431-9. [PMID: 22502774 DOI: 10.1016/j.tplants.2012.03.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 03/13/2012] [Accepted: 03/15/2012] [Indexed: 05/08/2023]
Abstract
Retromer is a cytosolic protein complex which binds to post-Golgi organelles involved in the trafficking of proteins to the lytic compartment of the cell. In non-plant organisms, retromer mediates the recycling of acid hydrolase receptors from early endosomal (EE) compartments. In plants, retromer components are required for the targeting of vacuolar storage proteins, and for the recycling of endocytosed PIN proteins. However, there are contradictory reports as to the localization of the sorting nexins and the core subunit of retromer. There is also uncertainty as to the identity of the organelles from which vacuolar sorting receptors (VSRs) and endocytosed plasma membrane (PM) proteins are recycled. In this review we try to resolve some of these conflicting observations.
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Affiliation(s)
- David G Robinson
- Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany.
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Cai Y, Zhuang X, Wang J, Wang H, Lam SK, Gao C, Wang X, Jiang L. Vacuolar degradation of two integral plasma membrane proteins, AtLRR84A and OsSCAMP1, is cargo ubiquitination-independent and prevacuolar compartment-mediated in plant cells. Traffic 2012; 13:1023-40. [PMID: 22486829 DOI: 10.1111/j.1600-0854.2012.01360.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2012] [Revised: 04/02/2012] [Accepted: 04/04/2012] [Indexed: 12/31/2022]
Abstract
In plant cells, how integral plasma membrane (PM) proteins are degraded in a cargo ubiquitination-independent manner remains elusive. Here, we studied the degradative pathway of two plant PM proteins: AtLRR84A, a type I integral membrane protein belonging to the leucine-rich repeat receptor-like kinase protein family, and OsSCAMP1 (rice secretory carrier membrane protein 1), a tetraspan transmembrane protein located on the PM and trans-Golgi network (TGN) or early endosome (EE). Using wortmannin and ARA7(Q69L) mutant that could enlarge the multivesicular body (MVB) or prevacuolar compartment (PVC) as tools, we demonstrated that, when expressed as green fluorescent protein (GFP) fusions in tobacco BY-2 or Arabidopsis protoplasts, both AtLRR84A and OsSCAMP1 were degraded in the lytic vacuole via the internal vesicles of MVB/PVC in a cargo ubiquitination-independent manner. Such MVB/PVC-mediated vacuolar degradation of PM proteins was further supported by immunocytochemical electron microscopy (immunoEM) study showing the labeling of the fusions on the internal vesicles of the PVC/MVB. Thus, cargo ubiquitination-independent and PVC-mediated degradation of PM proteins in the vacuole is functionally operated in plant cells.
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Affiliation(s)
- Yi Cai
- School of Life Sciences, Centre for Cell and Developmental Biology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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Langhans M, Meckel T, Kress A, Lerich A, Robinson DG. ERES (ER exit sites) and the "secretory unit concept". J Microsc 2012; 247:48-59. [PMID: 22360601 DOI: 10.1111/j.1365-2818.2011.03597.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The higher plant Golgi apparatus consists of hundreds of individual Golgi stacks which move along the cortical ER, propelled by the actomysin system. Anterograde and retrograde transport between the endoplasmic reticulum (ER) and the plant Golgi occurs over a narrow interface (around 500 nm) and is generally considered to be mediated by COP-coated vesicles. Previously, ER exit sites (ERES) have been identified on the basis of to localization of transiently expressed COPII-coat proteins. As a consequence it has been held that ERES in higher plants are intimately associated with Golgi stacks, and that both move together as an integrated structure: the "secretory unit". Using a new COPII marker, as well as YFP-SEC24 (a bona fide COPII coat protein), we have made observations on tobacco leaf epidermis at high resolution in the CLSM. Our data clearly shows that COPII fluorescence is associated with the Golgi stacks rather than the surface of the ER and probably represents the temporary accumulation of COPII vesicles in the Golgi matrix prior to fusion with the cis-Golgi cisternae. We have calculated the numbers of COPII vesicles which would be required to provide a typical Golgi-associated COPII-fluorescent signal as being much less than 20. We have discussed the consequences of this and question the continued usage of the term "secretory unit".
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Affiliation(s)
- M Langhans
- Department of Plant Cell Biology, Centre for Organismal Biology, University of Heidelberg, Germany
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