1
|
Park H, Youn B, Park DJ, Puthanveettil SV, Kang C. Functional implication of the homotrimeric multidomain vacuolar sorting receptor 1 (VSR1) from Arabidopsis thaliana. Sci Rep 2024; 14:9622. [PMID: 38671060 PMCID: PMC11052993 DOI: 10.1038/s41598-024-57975-2] [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: 01/13/2024] [Accepted: 03/23/2024] [Indexed: 04/28/2024] Open
Abstract
The vacuolar sorting receptors (VSRs) are specific to plants and are responsible for sorting and transporting particular proteins from the trans-Golgi network to the vacuole. This process is critically important for various cellular functions, including storing nutrients during seed development. Despite many years of intense studies on VSRs, a complete relation between function and structure has not yet been revealed. Here, we present the crystal structure of the entire luminal region of glycosylated VSR1 from Arabidopsis thaliana (AtVSR1) for the first time. The structure provides insights into the tertiary and quaternary structures of VSR1, which are composed of an N-terminal protease-associated (PA) domain, a unique central region, and one epidermal growth factor (EGF)-like domain followed by two disordered EGF-like domains. The structure of VSR1 exhibits unique characteristics, the significance of which is yet to be fully understood.
Collapse
Affiliation(s)
- HaJeung Park
- X-Ray Core, UF Scripps Biomedical Research, University of Florida, Jupiter, FL, 33458, USA
| | - BuHyun Youn
- Department of Biological Sciences, Pusan National University, Busan, 46241, Republic of Korea
| | - Daniel J Park
- Burnett School of Biomedical Sciences, University of Central Florida, Orlando, FL, 32827, USA
| | | | - ChulHee Kang
- Department of Chemistry, Washington State University, Pullman, WA, 99164, USA.
| |
Collapse
|
2
|
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.
Collapse
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.
| |
Collapse
|
3
|
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.
Collapse
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.
| |
Collapse
|
4
|
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.
Collapse
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
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
Nozoye T, von Wirén N, Sato Y, Higashiyama T, Nakanishi H, Nishizawa NK. Characterization of the Nicotianamine Exporter ENA1 in Rice. FRONTIERS IN PLANT SCIENCE 2019; 10:502. [PMID: 31114596 PMCID: PMC6503003 DOI: 10.3389/fpls.2019.00502] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 04/01/2019] [Indexed: 05/23/2023]
Abstract
Under iron (Fe) deficiency, graminaceous plants produce and secrete Fe-chelating phytosiderophores of the mugineic acid (MA) family into the rhizosphere to solubilize and mediate uptake of sparingly soluble Fe in the soil. MAs and their biosynthetic intermediate, nicotianamine (NA), are also important for the translocation of divalent metals such as Fe and zinc (Zn) throughout the plant body. In this study, the physiological role of the efflux transporter EFFLUX TRANSPORTER OF NA (ENA1), which exports NA out of cells, was analyzed in rice. Promoter-GUS analysis showed that ENA1 was mainly expressed in roots, and strongly upregulated under Fe-deficient conditions. In epidermal onion cells and rice roots, green fluorescent protein-tagged ENA1 localized mainly to the plasma membrane, while a part of the fluorescence was observed in vesicular structures in the cytoplasm. In the younger stage after germination, ENA1-overexpressing rice plants exhibited truncated roots with many root hairs compared to wild-type plants, while these phenotype were not observed in high Zn-containing medium. In Arabidopsis, which use a different strategy for Fe uptake from rice, ENA1 overexpression did not show any apparent phenotypes. Oligo DNA microarray analysis in rice showed that ENA1 knockout affects the response to stress, especially in root plastids. These results suggest that ENA1 might be recycling between the plasma membrane and cellular compartments by vesicular transport, playing an important role in the transport of NA, which is important for the physiological response to Fe deficiency.
Collapse
Affiliation(s)
- Tomoko Nozoye
- Center for Liberal Arts, Meiji Gakuin University, Tokyo, Japan
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
- *Correspondence: Tomoko Nozoye,
| | - Nicolaus von Wirén
- Molecular Plant Nutrition, Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany
| | - Yoshikatsu Sato
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, Japan
| | - Tetsuya Higashiyama
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, Japan
| | - Hiromi Nakanishi
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Naoko K. Nishizawa
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
- Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, Nonoichi, Japan
| |
Collapse
|
7
|
Ashnest JR, Gendall AR. Trafficking to the seed protein storage vacuole. FUNCTIONAL PLANT BIOLOGY : FPB 2018; 45:895-910. [PMID: 32291054 DOI: 10.1071/fp17318] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 02/17/2018] [Indexed: 06/11/2023]
Abstract
The processing and subcellular trafficking of seed storage proteins is a critical area of physiological, agricultural and biotechnological research. Trafficking to the lytic vacuole has been extensively discussed in recent years, without substantial distinction from trafficking to the protein storage vacuole (PSV). However, despite some overlap between these pathways, there are several examples of unique processing and machinery in the PSV pathway. Moreover, substantial new data has recently come to light regarding the important players in this pathway, in particular, the intracellular NHX proteins and their role in regulating lumenal pH. In some cases, these new data are limited to genetic evidence, with little mechanistic understanding. As such, the implications of these data in the current paradigm of PSV trafficking is perhaps yet unclear. Although it has generally been assumed that the major classes of storage proteins are trafficked via the same pathway, there is mounting evidence that the 12S globulins and 2S albumins may be trafficked independently. Advances in identification of vacuolar targeting signals, as well as an improved mechanistic understanding of various vacuolar sorting receptors, may reveal the differences in these trafficking pathways.
Collapse
Affiliation(s)
- Joanne R Ashnest
- Department of Animal, Plant and Soil Sciences, AgriBio, Centre for AgriBiosciences, 5 Ring Road, La Trobe University, Bundoora, Vic. 3086, Australia
| | - Anthony R Gendall
- Department of Animal, Plant and Soil Sciences, AgriBio, Centre for AgriBiosciences, 5 Ring Road, La Trobe University, Bundoora, Vic. 3086, Australia
| |
Collapse
|
8
|
Abstract
Plant vacuoles are multifunctional organelles. On the one hand, most vegetative tissues develop lytic vacuoles that have a role in degradation. On the other hand, seed cells have two types of storage vacuoles: protein storage vacuoles (PSVs) in endosperm and embryonic cells and metabolite storage vacuoles in seed coats. Vacuolar proteins and metabolites are synthesized on the endoplasmic reticulum and then transported to the vacuoles via Golgi-dependent and Golgi-independent pathways. Proprotein precursors delivered to the vacuoles are converted into their respective mature forms by vacuolar processing enzyme, which also regulates various kinds of programmed cell death in plants. We summarize two types of vacuolar membrane dynamics that occur during defense responses: vacuolar membrane collapse to attack viral pathogens and fusion of vacuolar and plasma membranes to attack bacterial pathogens. We also describe the chemical defense against herbivores brought about by the presence of PSVs in the idioblast myrosin cell.
Collapse
Affiliation(s)
- Tomoo Shimada
- Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan;
| | - Junpei Takagi
- Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan;
- Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
- Graduate School of Natural Science, Konan University, Kobe 658-8501, Japan
| | - Takuji Ichino
- Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan;
- Research Institute for Sustainable Humanosphere, Kyoto University, Uji 611-0011, Japan
| | - Makoto Shirakawa
- Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan;
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma 630-0192, Japan
| | - Ikuko Hara-Nishimura
- Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan;
- Graduate School of Natural Science, Konan University, Kobe 658-8501, Japan
| |
Collapse
|
9
|
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.
Collapse
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.
| |
Collapse
|
10
|
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.
Collapse
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.
| |
Collapse
|
11
|
Cui Y, He Y, Cao W, Gao J, Jiang L. The Multivesicular Body and Autophagosome Pathways in Plants. FRONTIERS IN PLANT SCIENCE 2018; 9:1837. [PMID: 30619408 PMCID: PMC6299029 DOI: 10.3389/fpls.2018.01837] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 11/27/2018] [Indexed: 05/03/2023]
Abstract
In eukaryotic cells, the endomembrane system consists of multiple membrane-bound organelles, which play essential roles in the precise transportation of various cargo proteins. In plant cells, vacuoles are regarded as the terminus of catabolic pathways whereas the selection and transport of vacuolar cargoes are mainly mediated by two types of organelles, multivesicular bodies (MVBs) also termed prevacuolar compartments (PVCs) and autophagosomes. MVBs are single-membrane bound organelles with intraluminal vesicles and mediate the transport between the trans-Golgi network (TGN) and vacuoles, while autophagosomes are double-membrane bound organelles, which mediate cargo delivery to the vacuole for degradation and recycling during autophagy. Great progress has been achieved recently in identification and characterization of the conserved and plant-unique regulators involved in the MVB and autophagosome pathways. In this review, we present an update on the current knowledge of these key regulators and pay special attention to their conserved protein domains. In addition, we discuss the possible interplay between the MVB and autophagosome pathways in regulating vacuolar degradation in plants.
Collapse
Affiliation(s)
- Yong Cui
- Centre for Cell and Developmental Biology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong
- *Correspondence: Yong Cui, Liwen Jiang,
| | - Yilin He
- Centre for Cell and Developmental Biology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Wenhan Cao
- Centre for Cell and Developmental Biology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Jiayang Gao
- Centre for Cell and Developmental Biology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Liwen Jiang
- Centre for Cell and Developmental Biology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong
- The Chinese University of Hong Kong Shenzhen Research Institute, Shenzhen, China
- *Correspondence: Yong Cui, Liwen Jiang,
| |
Collapse
|
12
|
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.
Collapse
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
| |
Collapse
|
13
|
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.
Collapse
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
| |
Collapse
|
14
|
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.
Collapse
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
| |
Collapse
|
15
|
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.
Collapse
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.
| |
Collapse
|
16
|
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.
Collapse
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
| |
Collapse
|
17
|
Luo F, Fong YH, Zeng Y, Shen J, Jiang L, Wong KB. How vacuolar sorting receptor proteins interact with their cargo proteins: crystal structures of apo and cargo-bound forms of the protease-associated domain from an Arabidopsis vacuolar sorting receptor. THE PLANT CELL 2014; 26:3693-708. [PMID: 25271241 PMCID: PMC4213161 DOI: 10.1105/tpc.114.129940] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
In plant cells, soluble proteins are directed to vacuoles because they contain vacuolar sorting determinants (VSDs) that are recognized by vacuolar sorting receptors (VSR). To understand how a VSR recognizes its cargo, we present the crystal structures of the protease-associated domain of VSR isoform 1 from Arabidopsis thaliana (VSR1PA) alone and complexed with a cognate peptide containing the barley (Hordeum vulgare) aleurain VSD sequence of 1ADSNPIRPVT10. The crystal structures show that VSR1PA binds the sequence, Ala-Asp-Ser, preceding the NPIR motif. A conserved cargo binding loop, with a consensus sequence of 95RGxCxF100, forms a cradle that accommodates the cargo-peptide. In particular, Arg-95 forms a hydrogen bond to the Ser-3 position of the VSD, and the essential role of Arg-95 and Ser-3 in receptor-cargo interaction was supported by a mutagenesis study. Cargo binding induces conformational changes that are propagated from the cargo binding loop to the C terminus via conserved residues in switch I-IV regions. The resulting 180° swivel motion of the C-terminal tail is stabilized by a hydrogen bond between Glu-24 and His-181. A mutagenesis study showed that these two residues are essential for cargo interaction and trafficking. Based on our structural and functional studies, we present a model of how VSRs recognize their cargos.
Collapse
Affiliation(s)
- Fang Luo
- Centre for Protein Science and Crystallography, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Yu Hang Fong
- Centre for Protein Science and Crystallography, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Yonglun Zeng
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Jinbo Shen
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Liwen Jiang
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Kam-Bo Wong
- Centre for Protein Science and Crystallography, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| |
Collapse
|
18
|
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.
Collapse
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.
| |
Collapse
|
19
|
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.
Collapse
Affiliation(s)
- David G Robinson
- Centre for Organismal Studies (COS), University of Heidelberg, Heidelberg, Germany
| | | |
Collapse
|
20
|
Martinière A, Bassil E, Jublanc E, Alcon C, Reguera M, Sentenac H, Blumwald E, Paris N. In vivo intracellular pH measurements in tobacco and Arabidopsis reveal an unexpected pH gradient in the endomembrane system. THE PLANT CELL 2013; 25:4028-43. [PMID: 24104564 PMCID: PMC3877828 DOI: 10.1105/tpc.113.116897] [Citation(s) in RCA: 134] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 07/30/2013] [Accepted: 09/18/2013] [Indexed: 05/18/2023]
Abstract
The pH homeostasis of endomembranes is essential for cellular functions. In order to provide direct pH measurements in the endomembrane system lumen, we targeted genetically encoded ratiometric pH sensors to the cytosol, the endoplasmic reticulum, and the trans-Golgi, or the compartments labeled by the vacuolar sorting receptor (VSR), which includes the trans-Golgi network and prevacuoles. Using noninvasive live-cell imaging to measure pH, we show that a gradual acidification from the endoplasmic reticulum to the lytic vacuole exists, in both tobacco (Nicotiana tabacum) epidermal (ΔpH -1.5) and Arabidopsis thaliana root cells (ΔpH -2.1). The average pH in VSR compartments was intermediate between that of the trans-Golgi and the vacuole. Combining pH measurements with in vivo colocalization experiments, we found that the trans-Golgi network had an acidic pH of 6.1, while the prevacuole and late prevacuole were both more alkaline, with pH of 6.6 and 7.1, respectively. We also showed that endosomal pH, and subsequently vacuolar trafficking of soluble proteins, requires both vacuolar-type H(+) ATPase-dependent acidification as well as proton efflux mediated at least by the activity of endosomal sodium/proton NHX-type antiporters.
Collapse
Affiliation(s)
- Alexandre Martinière
- Biochemistry and Plant Molecular Biology Lab, Unité Mixte de Recherche 5004, 34060 Montpellier, France
| | - Elias Bassil
- Department of Plant Sciences, University of California, Davis, California 95616
| | - Elodie Jublanc
- Institut National de la Recherche Agronomique, Unité Mixte de Recherche 866, Dynamique Musculaire et Métabolisme, 34060 Montpellier, France
| | - Carine Alcon
- Biochemistry and Plant Molecular Biology Lab, Unité Mixte de Recherche 5004, 34060 Montpellier, France
| | - Maria Reguera
- Department of Plant Sciences, University of California, Davis, California 95616
| | - Hervé Sentenac
- Biochemistry and Plant Molecular Biology Lab, Unité Mixte de Recherche 5004, 34060 Montpellier, France
| | - Eduardo Blumwald
- Department of Plant Sciences, University of California, Davis, California 95616
| | - Nadine Paris
- Biochemistry and Plant Molecular Biology Lab, Unité Mixte de Recherche 5004, 34060 Montpellier, France
| |
Collapse
|
21
|
Martinière A, Desbrosses G, Sentenac H, Paris N. Development and properties of genetically encoded pH sensors in plants. FRONTIERS IN PLANT SCIENCE 2013; 4:523. [PMID: 24391657 PMCID: PMC3866548 DOI: 10.3389/fpls.2013.00523] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 12/04/2013] [Indexed: 05/06/2023]
Abstract
Fluorescent proteins (FPs) have given access to a large choice of live imaging techniques and have thereby profoundly modified our view of plant cells. Together with technological improvement of imaging, they have opened the possibility to monitor physico-chemical changes within cells. For this purpose, a new generation of FPs has been engineered. For instance, pHluorin, a point mutated version of green fluorescent protein, allows to get local pH estimates. In this paper, we will describe how genetically encoded sensors can be used to measure pH in the microenvironment of living tissues and subsequently discuss the role of pH in (i) exocytosis, (ii) ion uptake by plant roots, (iii) cell growth, and (iv) protein trafficking.
Collapse
Affiliation(s)
- Alexandre Martinière
- Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, UMR 5004 CNRS/UMR 0386 INRA/Montpellier SupAgro/Université Montpellier 2Montpellier, France
- *Correspondence: Alexandre Martinière and Nadine Paris, Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, UMR 5004 CNRS/UMR 0386 INRA/Montpellier SupAgro/Université Montpellier 2, F-34060 Montpellier Cedex 1, France. e-mail: ;
| | - Guilhem Desbrosses
- Laboratory of Tropical and Mediterranean Symbioses (UMR113, Université Montpellier 2, Institut de Recherche pour le Développement, Cirad Montpellier SupAgro, Institut National de la Recherche Agronomique), Université Montpellier 2Montpellier, France
| | - Hervé Sentenac
- Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, UMR 5004 CNRS/UMR 0386 INRA/Montpellier SupAgro/Université Montpellier 2Montpellier, France
| | - Nadine Paris
- Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, UMR 5004 CNRS/UMR 0386 INRA/Montpellier SupAgro/Université Montpellier 2Montpellier, France
- *Correspondence: Alexandre Martinière and Nadine Paris, Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, UMR 5004 CNRS/UMR 0386 INRA/Montpellier SupAgro/Université Montpellier 2, F-34060 Montpellier Cedex 1, France. e-mail: ;
| |
Collapse
|
22
|
Richau KH, Kaschani F, Verdoes M, Pansuriya TC, Niessen S, Stüber K, Colby T, Overkleeft HS, Bogyo M, Van der Hoorn RA. Subclassification and biochemical analysis of plant papain-like cysteine proteases displays subfamily-specific characteristics. PLANT PHYSIOLOGY 2012; 158:1583-99. [PMID: 22371507 PMCID: PMC3320171 DOI: 10.1104/pp.112.194001] [Citation(s) in RCA: 126] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 02/24/2012] [Indexed: 05/18/2023]
Abstract
Papain-like cysteine proteases (PLCPs) are a large class of proteolytic enzymes associated with development, immunity, and senescence. Although many properties have been described for individual proteases, the distribution of these characteristics has not been studied collectively. Here, we analyzed 723 plant PLCPs and classify them into nine subfamilies that are present throughout the plant kingdom. Analysis of these subfamilies revealed previously unreported distinct subfamily-specific functional and structural characteristics. For example, the NPIR and KDEL localization signals are distinctive for subfamilies, and the carboxyl-terminal granulin domain occurs in two PLCP subfamilies, in which some individual members probably evolved by deletion of the granulin domains. We also discovered a conserved double cysteine in the catalytic site of SAG12-like proteases and two subfamily-specific disulfides in RD19A-like proteases. Protease activity profiling of representatives of the PLCP subfamilies using novel fluorescent probes revealed striking polymorphic labeling profiles and remarkably distinct pH dependency. Competition assays with peptide-epoxide scanning libraries revealed common and unique inhibitory fingerprints. Finally, we expand the detection of PLCPs by identifying common and organ-specific protease activities and identify previously undetected proteases upon labeling with cell-penetrating probes in vivo. This study provides the plant protease research community with tools for further functional annotation of plant PLCPs.
Collapse
|
23
|
Ibl V, Stoger E. The formation, function and fate of protein storage compartments in seeds. PROTOPLASMA 2012; 249:379-92. [PMID: 21614590 DOI: 10.1007/s00709-011-0288-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 05/12/2011] [Indexed: 05/07/2023]
Abstract
Seed storage proteins (SSPs) have been studied for more than 250 years because of their nutritional value and their impact on the use of grain in food processing. More recently, the use of seeds for the production of recombinant proteins has rekindled interest in the behavior of SSPs and the question how they are able to accumulate as stable storage reserves. Seed cells produce vast amounts of SSPs with different subcellular destinations creating an enormous logistic challenge for the endomembrane system. Seed cells contain several different storage organelles including the complex and dynamic protein storage vacuoles (PSVs) and other protein bodies (PBs) derived from the endoplasmic reticulum (ER). Storage proteins destined for the PSV may pass through or bypass the Golgi, using different vesicles that follow different routes through the cell. In addition, trafficking may depend on the plant species, tissue and developmental stage, showing that the endomembrane system is capable of massive reorganization. Some SSPs contain sorting signals or interact with membranes or with other proteins en route in order to reach their destination. The ability of SSPs to form aggregates is particularly important in the formation or ER-derived PBs, a mechanism that occurs naturally in response to overloading with proteins that cannot be transported and that can be used to induce artificial storage bodies in vegetative tissues. In this review, we summarize recent findings that provide insight into the formation, function, and fate of storage organelles and describe tools that can be used to study them.
Collapse
Affiliation(s)
- Verena Ibl
- Department for Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Muthgasse 18, 1190, Vienna, Austria
| | | |
Collapse
|
24
|
Zouhar J, Muñoz A, Rojo E. Functional specialization within the vacuolar sorting receptor family: VSR1, VSR3 and VSR4 sort vacuolar storage cargo in seeds and vegetative tissues. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 64:577-88. [PMID: 20807215 DOI: 10.1111/j.1365-313x.2010.04349.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Two different gene families have been proposed to act as sorting receptors for vacuolar storage cargo in plants: the vacuolar sorting receptors (VSRs) and the receptor homology-transmembrane-RING H2 domain proteins (RMRs). However, functional data on these genes is scarce and the identity of the sorting receptor for storage proteins remains controversial. Through a genetic screen we have identified the mtv2 mutant, which is defective in vacuolar transport of the storage cargo VAC2 in shoot apices. Map-based cloning revealed that mtv2 is a loss of function allele of the VSR4 gene. We show that VSR1, VSR3 and VSR4, but not the remaining VSRs or RMRs, participate in vacuolar sorting of VAC2 in vegetative tissues, and 12S globulins and 2S albumins in seeds, an activity that is essential for seedling germination vigor. Finally, we demonstrate that the functional diversification in the VSR family results from divergent expression patterns and also from distinct sorting activities of the family members.
Collapse
Affiliation(s)
- Jan Zouhar
- Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología-CSIC, E-28049 Madrid, Spain
| | | | | |
Collapse
|
25
|
Kim H, Kang H, Jang M, Chang JH, Miao Y, Jiang L, Hwang I. Homomeric interaction of AtVSR1 is essential for its function as a vacuolar sorting receptor. PLANT PHYSIOLOGY 2010; 154:134-48. [PMID: 20625000 PMCID: PMC2938145 DOI: 10.1104/pp.110.159814] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Vacuolar sorting receptors, BP80/VSRs, play a critical role in vacuolar trafficking of soluble proteins in plant cells. However, the mechanism of action of BP80 is not well understood. Here, we investigate the action mechanism of AtVSR1, a member of BP80 proteins in Arabidopsis (Arabidopsis thaliana), in vacuolar trafficking. AtVSR1 exists as multiple forms, including a high molecular mass homomeric complex in vivo. Both the transmembrane and carboxyl-terminal cytoplasmic domains of AtVSR1 are necessary for the homomeric interaction. The carboxyl-terminal cytoplasmic domain contains specific sequence information, whereas the transmembrane domain has a structural role in the homomeric interaction. In protoplasts, an AtVSR1 mutant, C2A, that contained alanine substitution of the region involved in the homomeric interaction, was defective in trafficking to the prevacuolar compartment and localized primarily to the trans-Golgi network. In addition, overexpression of C2A, but not wild-type AtVSR1, inhibited trafficking of soluble proteins to the vacuole and caused their secretion into the medium. Furthermore, C2A:hemagglutinin in transgenic plants interfered with the homomeric interaction of endogenous AtVSR1 and inhibited vacuolar trafficking of sporamin:green fluorescent protein. These data suggest that homomeric interaction of AtVSR1 is critical for its function as a vacuolar sorting receptor.
Collapse
|
26
|
Saint-Jean B, Seveno-Carpentier E, Alcon C, Neuhaus JM, Paris N. The cytosolic tail dipeptide Ile-Met of the pea receptor BP80 is required for recycling from the prevacuole and for endocytosis. THE PLANT CELL 2010; 22:2825-37. [PMID: 20807880 PMCID: PMC2947187 DOI: 10.1105/tpc.109.072215] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2009] [Revised: 06/24/2010] [Accepted: 08/05/2010] [Indexed: 05/18/2023]
Abstract
Pea (Pisum sativum) BP80 is a vacuolar sorting receptor for soluble proteins and has a cytosolic domain essential for its intracellular trafficking between the trans-Golgi network and the prevacuole. Based on mammalian knowledge, we introduced point mutations in the cytosolic region of the receptor and produced chimeras of green fluorescent protein fused to the transmembrane domain of pea BP80 along with the modified cytosolic tails. By analyzing the subcellular location of these chimera, we found that mutating Glu-604, Asp-616, or Glu-620 had mild effects, whereas mutating the Tyr motif partially redistributed the chimera to the plasma membrane. Replacing both Ile-608 and Met-609 by Ala (IMAA) led to a massive redistribution of fluorescence to the vacuole, indicating that recycling is impaired. When the chimera uses the alternative route, the IMAA mutation led to a massive accumulation at the plasma membrane. Using Arabidopsis thaliana plants expressing a fluorescent reporter with the full-length sequence of At VSR4, we demonstrated that the receptor undergoes brefeldin A-sensitive endocytosis. We conclude that the receptors use two pathways, one leading directly to the lytic vacuole and the other going via the plasma membrane, and that the Ileu-608 Met-609 motif has a role in the retrieval step in both pathways.
Collapse
Affiliation(s)
- Bruno Saint-Jean
- Laboratoire de Physiologie et Biotechnologie des Algues, Institut Français de Recherche pour l'Exploitation de la Mer, 44311 Nantes Cedex 03, France
| | - Emilie Seveno-Carpentier
- Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, Unité Mixte de Recherche 5004, Centre National de la Recherche Scientifique/Unité Mixte de Recherche 0386, Institut National de la Recherche Agronomique/Montpellier SupAgro/Université Montpellier 2, F-34060 Montpellier Cedex 1, France
| | - Carine Alcon
- Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, Unité Mixte de Recherche 5004, Centre National de la Recherche Scientifique/Unité Mixte de Recherche 0386, Institut National de la Recherche Agronomique/Montpellier SupAgro/Université Montpellier 2, F-34060 Montpellier Cedex 1, France
| | - Jean-Marc Neuhaus
- Laboratoire de Biologie Moléculaire et Cellulaire, Université de Neuchâtel, CH-2009 Neuchâtel, Switzerland
| | - Nadine Paris
- Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, Unité Mixte de Recherche 5004, Centre National de la Recherche Scientifique/Unité Mixte de Recherche 0386, Institut National de la Recherche Agronomique/Montpellier SupAgro/Université Montpellier 2, F-34060 Montpellier Cedex 1, France
| |
Collapse
|
27
|
Niemes S, Labs M, Scheuring D, Krueger F, Langhans M, Jesenofsky B, Robinson DG, Pimpl P. Sorting of plant vacuolar proteins is initiated in the ER. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 62:601-14. [PMID: 20149141 DOI: 10.1111/j.1365-313x.2010.04171.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Transport of soluble cargo molecules to the lytic vacuole of plants requires vacuolar sorting receptors (VSRs) to divert transport of vacuolar cargo from the default secretory route to the cell surface. Just as important is the trafficking of the VSRs themselves, a process that encompasses anterograde transport of receptor-ligand complexes from a donor compartment, dissociation of these complexes upon arrival at the target compartment, and recycling of the receptor back to the donor compartment for a further round of ligand transport. We have previously shown that retromer-mediated recycling of the plant VSR BP80 starts at the trans-Golgi network (TGN). Here we demonstrate that inhibition of retromer function by either RNAi knockdown of sorting nexins (SNXs) or co-expression of mutants of SNX1/2a specifically inhibits the ER export of VSRs as well as soluble vacuolar cargo molecules, but does not influence cargo molecules destined for the COPII-mediated transport route. Retention of soluble cargo despite ongoing COPII-mediated bulk flow can only be explained by an interaction with membrane-bound proteins. Therefore, we examined whether VSRs are capable of binding their ligands in the lumen of the ER by expressing ER-anchored VSR derivatives. These experiments resulted in drastic accumulation of soluble vacuolar cargo molecules in the ER. This demonstrates that the ER, rather than the TGN, is the location of the initial VSR-ligand interaction. It also implies that the retromer-mediated recycling route for the VSRs leads from the TGN back to the ER.
Collapse
Affiliation(s)
- Silke Niemes
- Department of Cell Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, Germany
| | | | | | | | | | | | | | | |
Collapse
|
28
|
Kaschani F, Verhelst SHL, van Swieten PF, Verdoes M, Wong CS, Wang Z, Kaiser M, Overkleeft HS, Bogyo M, van der Hoorn RAL. Minitags for small molecules: detecting targets of reactive small molecules in living plant tissues using 'click chemistry'. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 57:373-85. [PMID: 18786180 DOI: 10.1111/j.1365-313x.2008.03683.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Small molecules offer unprecedented opportunities for plant research since plants respond to, metabolize, and react with a diverse range of endogenous and exogenous small molecules. Many of these small molecules become covalently attached to proteins. To display these small molecule targets in plants, we introduce a two-step labelling method for minitagged small molecules. Minitags are small chemical moieties (azide or alkyne) that are inert under biological conditions and have little influence on the membrane permeability and specificity of the small molecule. After labelling, proteomes are extracted under denaturing conditions and minitagged proteins are coupled to reporter tags through a 'click chemistry' reaction. We introduce this two-step labelling procedure in plants by studying the well-characterized targets of E-64, a small molecule cysteine protease inhibitor. In contrast to biotinylated E-64, minitagged E-64 efficiently labels vacuolar proteases in vivo. We displayed, purified and identified targets of a minitagged inhibitor that targets the proteasome and cysteine proteases in living plant cells. Chemical interference assays with inhibitors showed that MG132, a frequently used proteasome inhibitor, preferentially inhibits cysteine proteases in vivo. The two-step labelling procedure can be applied on detached leaves, cell cultures, seedlings and other living plant tissues and, when combined with photoreactive groups, can be used to identify targets of herbicides, phytohormones and reactive small molecules selected from chemical genetic screens.
Collapse
Affiliation(s)
- Farnusch Kaschani
- Plant Chemetics Lab, Chemical Genomics Centre of the Max Planck Society, Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829 Cologne, Germany
| | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Foresti O, Denecke J. Intermediate organelles of the plant secretory pathway: identity and function. Traffic 2008; 9:1599-612. [PMID: 18627574 DOI: 10.1111/j.1600-0854.2008.00791.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The secretory pathway of eukaryotic cells comprises a network of organelles that connects three large membranes, the plasma membrane, the vacuole and the endoplasmic reticulum. The Golgi apparatus and the various post-Golgi organelles that control vacuolar sorting, secretion and endocytosis can be regarded as intermediate organelles of the endocytic and biosynthetic routes. Many processes in the secretory pathway have evolved differently in plants and cannot be studied using yeast or mammalian cells as models. The best characterized organelles are the Golgi apparatus and the prevacuolar compartment, but recent work has shed light on the role of the trans Golgi network, which has to be regarded as a separate organelle in plants. In this study, we wish to highlight recent findings regarding the late secretory pathway and its crosstalk with the early secretory pathway as well as the endocytic route in plants. Recently published findings and suggested models are discussed within the context of known features of the equivalent pathway in other eukaryotes.
Collapse
Affiliation(s)
- Ombretta Foresti
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | | |
Collapse
|
30
|
Shabab M, Shindo T, Gu C, Kaschani F, Pansuriya T, Chintha R, Harzen A, Colby T, Kamoun S, van der Hoorn RAL. Fungal effector protein AVR2 targets diversifying defense-related cys proteases of tomato. THE PLANT CELL 2008; 20:1169-83. [PMID: 18451324 PMCID: PMC2390736 DOI: 10.1105/tpc.107.056325] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2007] [Revised: 03/12/2008] [Accepted: 04/04/2008] [Indexed: 05/07/2023]
Abstract
The interaction between the fungal pathogen Cladosporium fulvum and its host tomato (Solanum lycopersicum) is an ideal model to study suppression of extracellular host defenses by pathogens. Secretion of protease inhibitor AVR2 by C. fulvum during infection suggests that tomato papain-like cysteine proteases (PLCPs) are part of the tomato defense response. We show that the tomato apoplast contains a remarkable diversity of PLCP activities with seven PLCPs that fall into four different subfamilies. Of these PLCPs, transcription of only PIP1 and RCR3 is induced by treatment with benzothiadiazole, which triggers the salicylic acid-regulated defense pathway. Sequencing of PLCP alleles of tomato relatives revealed that only PIP1 and RCR3 are under strong diversifying selection, resulting in variant residues around the substrate binding groove. The doubled number of variant residues in RCR3 suggests that RCR3 is under additional adaptive selection, probably to prevent autoimmune responses. AVR2 selectively inhibits only PIP1 and RCR3, and one of the naturally occurring variant residues in RCR3 affects AVR2 inhibition. The higher accumulation of PIP1 protein levels compared with RCR3 indicates that PIP1 might be the real virulence target of AVR2 and that RCR3 acts as a decoy for AVR2 perception in plants carrying the Cf-2 resistance gene.
Collapse
Affiliation(s)
- Mohammed Shabab
- Plant Chemetics Lab, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany
| | | | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Yamazaki M, Shimada T, Takahashi H, Tamura K, Kondo M, Nishimura M, Hara-Nishimura I. Arabidopsis VPS35, a retromer component, is required for vacuolar protein sorting and involved in plant growth and leaf senescence. PLANT & CELL PHYSIOLOGY 2008; 49:142-56. [PMID: 18222962 DOI: 10.1093/pcp/pcn006] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The retromer complex is responsible for retrograde transport, which is coordinated with anterograde transport in the secretory pathway including vacuolar protein sorting. Yeast VPS35 is a component of the retromer complex that is essential for recognition of specific cargo molecules. The physiological function of VPS35 has not been determined in vacuolar protein sorting in higher organisms. Arabidopsis thaliana has three VPS35 homologs designated VPS35a, VPS35b and VPS35c. We isolated four vps35 mutants (vps35a-1, vps35b-1, vps35b-2 and vps35c-1) and then generated four double mutants and one triple mutant. vps35a-1 vps35c-1 exhibited no unusual phenotypes. On the other hand, vps35b-1 vps35c-1 and the triple mutant (vps35a-1 vps35b-2 vps35c-1) exhibited severe phenotypes: dwarfism, early leaf senescence and fragmentation of protein storage vacuoles (PSVs). In addition, these mutants mis-sorted storage proteins by secreting them out of the cells and accumulated a higher level of vacuolar sorting receptor (VSR) than the wild type. VPS35 was localized in pre-vacuolar compartments (PVCs), some of which contained VSR. VPS35 was immunoprecipitated with VPS29/MAG1, another component of the retromer complex. Our findings suggest that VPS35, mainly VPS35b, is involved in sorting proteins to PSVs in seeds, possibly by recycling VSR from PVCs to the Golgi complex, and is also involved in plant growth and senescence in vegetative organs.
Collapse
Affiliation(s)
- Misako Yamazaki
- Graduate School of Science, Kyoto University, Kyoto 606-8502 Japan
| | | | | | | | | | | | | |
Collapse
|
32
|
Fuji K, Shimada T, Takahashi H, Tamura K, Koumoto Y, Utsumi S, Nishizawa K, Maruyama N, Hara-Nishimura I. Arabidopsis vacuolar sorting mutants (green fluorescent seed) can be identified efficiently by secretion of vacuole-targeted green fluorescent protein in their seeds. THE PLANT CELL 2007; 19:597-609. [PMID: 17293568 PMCID: PMC1867321 DOI: 10.1105/tpc.106.045997] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Two Arabidopsis thaliana genes have been shown to function in vacuolar sorting of seed storage proteins: a vacuolar sorting receptor, VSR1/ATELP1, and a retromer component, MAIGO1 (MAG1)/VPS29. Here, we show an efficient and simple method for isolating vacuolar sorting mutants of Arabidopsis. The method was based on two findings in this study. First, VSR1 functioned as a sorting receptor for beta-conglycinin by recognizing the vacuolar targeting signal. Second, when green fluorescent protein (GFP) fusion with the signal (GFP-CT24) was expressed in vsr1, mag1/vps29, and wild-type seeds, both vsr1and mag1/vps29 gave strongly fluorescent seeds but the wild type did not, suggesting that a defect in vacuolar sorting provided fluorescent seeds by the secretion of GFP-CT24 out of the cells. We mutagenized transformant seeds expressing GFP-CT24. From approximately 3,000,000 lines of M2 seeds, we obtained >100 fluorescent seeds and designated them green fluorescent seed (gfs) mutants. We report 10 gfs mutants, all of which caused missorting of storage proteins. We mapped gfs1 to VSR1, gfs2 to KAM2/GRV2, gfs10 to the At4g35870 gene encoding a novel membrane protein, and the others to different loci. This method should provide valuable insights into the complex molecular mechanisms underlying vacuolar sorting of storage proteins.
Collapse
Affiliation(s)
- Kentaro Fuji
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Li L, Shimada T, Takahashi H, Ueda H, Fukao Y, Kondo M, Nishimura M, Hara-Nishimura I. MAIGO2 is involved in exit of seed storage proteins from the endoplasmic reticulum in Arabidopsis thaliana. THE PLANT CELL 2006; 18:3535-47. [PMID: 17194767 PMCID: PMC1785406 DOI: 10.1105/tpc.106.046151] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Seed storage proteins are synthesized on the endoplasmic reticulum (ER) as precursors and then transported to protein storage vacuoles, where they are processed into mature forms. Here, we isolated an Arabidopsis thaliana mutant, maigo2 (mag2), that accumulated the precursors of two major storage proteins, 2S albumin and 12S globulin, in dry seeds. mag2 seed cells contained many novel structures, with an electron-dense core that was composed of the precursor forms of 2S albumin. 12S globulins were segregated from 2S albumin and were localized in the matrix region of the structures together with the ER chaperones lumenal binding protein and protein disulfide isomerase, which were more abundant in mag2 seeds. The MAG2 gene was identified as At3g47700, and the MAG2 protein had a RINT-1/TIP20 domain in the C-terminal region. We found that some MAG2 molecules were peripherally associated with the ER membrane. MAG2 had an ability to bind to two ER-localized t-SNAREs (for target-soluble NSF [N-ethylmaleimide-sensitive fusion protein] attachment protein receptor; At Sec20 and At Ufe1). Our findings suggest that MAG2 functions in the transport of storage protein precursors between the ER and Golgi complex in plants.
Collapse
Affiliation(s)
- Lixin Li
- Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | | | | | | | | | | | | | | |
Collapse
|
34
|
Oliviusson P, Heinzerling O, Hillmer S, Hinz G, Tse YC, Jiang L, Robinson DG. Plant retromer, localized to the prevacuolar compartment and microvesicles in Arabidopsis, may interact with vacuolar sorting receptors. THE PLANT CELL 2006; 18:1239-52. [PMID: 16582012 PMCID: PMC1456867 DOI: 10.1105/tpc.105.035907] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2005] [Revised: 02/17/2006] [Accepted: 03/02/2006] [Indexed: 05/08/2023]
Abstract
Receptors for acid hydrolases destined for the lytic compartment in yeast and mammalian cells are retrieved from intermediate, endosomal organelles with the help of a pentameric protein complex called the retromer. We cloned the Arabidopsis thaliana homologs of the three yeast proteins (Vps35, Vps29, and Vps26) constituting the larger subunit of retromer and prepared antisera against them. With these antibodies, we demonstrated the presence of a retromer-like protein complex in salt extracts prepared from Arabidopsis microsomes. This complex is associated with membranes that coequilibrate with prevacuolar compartment markers and with high-density sedimenting membranes. Immunogold negative staining identified these membranes as 90-nm-diameter coated microvesicles. Confocal laser scanning immunofluorescence studies performed on tobacco (Nicotiana tabacum) BY-2 cells revealed high degrees of colabeling between all three retromer antisera and the prevacuolar compartment (PVC) markers PEP12 and vacuolar sorting receptor VSR(At-1). The presence of plant retromer at the surface of multivesicular bodies was also demonstrated by immunogold labeling of sections obtained from high-pressure frozen/freeze-substituted specimens. Treatment of BY-2 cells with wortmannin led to swelling of the PVC and a separation of the VPS35 and VSR signals. Preliminary data suggesting that retromer interacts with the cytosolic domain of a VSR were obtained by immunoprecipitation experiments performed on detergent-solubilized microsomes with Vps35 antibodies.
Collapse
Affiliation(s)
- Peter Oliviusson
- Department of Cell Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, 69120 Heidelberg, Germany
| | | | | | | | | | | | | |
Collapse
|
35
|
Hanton SL, Brandizzi F. Protein transport in the plant secretory pathwayThis review is one of a selection of papers published in the Special Issue on Plant Cell Biology. ACTA ACUST UNITED AC 2006. [DOI: 10.1139/b05-172] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The study of the plant secretory pathway is a relatively new field, developing rapidly over the last 30 years. Many exciting discoveries have already been made in this area, but as old questions are answered new ones become apparent. Our understanding of the functions and mechanisms of the plant secretory pathway is constantly expanding, in part because of the development of new technologies, mainly in bioimaging. The increasing accessibility of these new tools in combination with more established methods provides an ideal way to increase knowledge of the secretory pathway in plants. In this review we discuss recent developments in understanding protein transport between organelles in the plant secretory pathway.
Collapse
Affiliation(s)
- Sally L. Hanton
- Department of Biology, 112 Science Place, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
| | - Federica Brandizzi
- Department of Biology, 112 Science Place, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
| |
Collapse
|
36
|
Okamoto T. Transport of Proteases to the Vacuole: ER Export Bypassing Golgi? PLANT CELL MONOGRAPHS 2006. [DOI: 10.1007/7089_055] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
37
|
Masclaux FG, Galaud JP, Pont-Lezica R. The riddle of the plant vacuolar sorting receptors. PROTOPLASMA 2005; 226:103-8. [PMID: 16333569 DOI: 10.1007/s00709-005-0117-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2004] [Accepted: 02/24/2005] [Indexed: 05/05/2023]
Abstract
Proteins synthesized on membrane-bound ribosomes are sorted at the Golgi apparatus level for delivery to various cellular destinations: the plasma membrane or the extracellular space, and the lytic vacuole or lysosome. Sorting involves the assembly of vesicles, which preferentially package soluble proteins with a common destination. The selection of proteins for a particular vesicle type involves the recognition of proteins by specific receptors, such as the vacuolar sorting receptors for vacuolar targeting. Most eukaryotic organisms have one or two receptors to target proteins to the lytic vacuole. Surprisingly, plants have several members of the same family, seven in Arabidopsis thaliana. Why do plants have so many proteins to sort soluble proteins to their respective destinations? The presence of at least two types of vacuoles, lytic and storage, seems to be a partial answer. In this review we analyze the last experimental evidence supporting the presence of different subfamilies of plant vacuolar sorting receptors.
Collapse
Affiliation(s)
- F G Masclaux
- Surfaces Cellulaires et Signalisation chez les Végétaux, Unité Mixte de Recherche 5546 de Centre National de la Recherche Scientifique, Université Paul Sabatier, BP 42617 Auzeville, 31326 Castanet-Tolosan, France
| | | | | |
Collapse
|
38
|
Abstract
The vacuole of plant cells is no longer considered to be a single compartment with multifunctional properties. A lot of evidence now points to the presence of multiple functionally distinct vacuolar compartments, some existing side by side in the same cell. As a consequence, the plant Golgi apparatus is faced with the problem of recognizing proteins destined for lytic and storage vacuoles and segregating them individually from the flow of secretory proteins to the cell surface. In contrast to acid hydrolases, which are sorted by BP-80-like receptors at the trans-Golgi of plant cells, the identification of receptors for storage proteins has in many ways resembled 'the search for the Holy Grail'. There are several candidates for storage protein receptors, but in no single case is the evidence entirely convincing. Much of the problem lies in the lack of consensus, sorting sequences in the proteins investigated. Other difficulties stem from 'out-of-context' heterologous expression studies. Evidence is now accumulating for the participation of hydrophobic sequences in inducing the formation of protein aggregates in the early Golgi apparatus, for which classical sorting receptors do not appear to be necessary. This review critically examines the current situation and contrasts the differences between data obtained in situ and data obtained transgenically. It highlights the so-called 'dense-vesicle' pathway and culminates with a discussion on the hitherto neglected problem of the intracellular transport of storage protein processing enzymes.
Collapse
Affiliation(s)
- David G Robinson
- Heidelberg Institute for Plant Sciences, Cell Biology, University of Heidelberg, Im Neuenheimer Feld 230, D-69120 Heidelberg, Germany
| | | | | |
Collapse
|
39
|
Vitale A, Hinz G. Sorting of proteins to storage vacuoles: how many mechanisms? TRENDS IN PLANT SCIENCE 2005; 10:316-23. [PMID: 15950520 DOI: 10.1016/j.tplants.2005.05.001] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2005] [Revised: 03/24/2005] [Accepted: 05/24/2005] [Indexed: 05/02/2023]
Abstract
Vacuoles receive their proteins through the secretory pathway, this requires protein sorting signals and molecular machineries that, until recently, have been believed to be markedly distinct for lytic and storage vacuoles. However, new biochemical, morphological and genetic data indicate that the only known class of vacuolar sorting receptors, believed to be specific for lytic vacuoles, might also be involved in the sorting of certain storage proteins. Furthermore, storage vacuoles can have a complex multimembrane structure that is difficult to explain based on a single trafficking mechanism. A new array of possible molecular interactions is thus emerging that no longer supports a clear-cut distinction between the two types of vacuoles based on sorting signals and putative receptors.
Collapse
Affiliation(s)
- Alessandro Vitale
- Istituto di Biologia e Biotecnologia Agraria, CNR, 20133 Milano, Italy.
| | | |
Collapse
|
40
|
Hernández DH, Paris N, Neuhaus JM, Deloche O. The yeast Saccharomyces cerevisiae is not an efficient tool for in vivo studies of plant vacuolar sorting receptors. THE PLANT CELL 2005; 17:1339-42. [PMID: 15863520 PMCID: PMC1091758 DOI: 10.1105/tpc.105.032276] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
|
41
|
Abstract
The year 2004 represents a milestone for the biosensor research community: in this year, over 1000 articles were published describing experiments performed using commercially available systems. The 1038 papers we found represent an approximately 10% increase over the past year and demonstrate that the implementation of biosensors continues to expand at a healthy pace. We evaluated the data presented in each paper and compiled a 'top 10' list. These 10 articles, which we recommend every biosensor user reads, describe well-performed kinetic, equilibrium and qualitative/screening studies, provide comparisons between binding parameters obtained from different biosensor users, as well as from biosensor- and solution-based interaction analyses, and summarize the cutting-edge applications of the technology. We also re-iterate some of the experimental pitfalls that lead to sub-optimal data and over-interpreted results. We are hopeful that the biosensor community, by applying the hints we outline, will obtain data on a par with that presented in the 10 spotlighted articles. This will ensure that the scientific community at large can be confident in the data we report from optical biosensors.
Collapse
Affiliation(s)
- Rebecca L Rich
- Center for Biomolecular Interaction Analysis, University of Utah, Salt Lake City, UT 84132, USA
| | | |
Collapse
|
42
|
Abstract
Plant membrane trafficking shares many features with other eukaryotic organisms, including the machinery for vesicle formation and fusion. However, the plant endomembrane system lacks an ER-Golgi intermediate compartment, has numerous Golgi stacks and several types of vacuoles, and forms a transient compartment during cell division. ER-Golgi trafficking involves bulk flow and efficient recycling of H/KDEL-bearing proteins. Sorting in the Golgi stacks separates bulk flow to the plasma membrane from receptor-mediated trafficking to the lytic vacuole. Cargo for the protein storage vacuole is delivered from the endoplasmic reticulum (ER), cis-Golgi, and trans-Golgi. Endocytosis includes recycling of plasma membrane proteins from early endosomes. Late endosomes appear identical with the multivesiculate prevacuolar compartment that lies on the Golgi-vacuole trafficking pathway. In dividing cells, homotypic fusion of Golgi-derived vesicles forms the cell plate, which expands laterally by targeted vesicle fusion at its margin, eventually fusing with the plasma membrane.
Collapse
Affiliation(s)
- Gerd Jurgens
- ZMBP, Entwicklungsgenetik, Universitat Tubingen, 72076 Tubingen, Germany.
| |
Collapse
|