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Structural insights into how vacuolar sorting receptors recognize the sorting determinants of seed storage proteins. Proc Natl Acad Sci U S A 2022; 119:2111281119. [PMID: 34983843 PMCID: PMC8740768 DOI: 10.1073/pnas.2111281119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/17/2021] [Indexed: 01/01/2023] Open
Abstract
Seeds such as rice and soybean are major food staples in the human diet. During seed development, storage proteins are deposited in a specialized organelle called the protein storage vacuole and are mobilized to provide nutrients during germination. Storage proteins are transported as cargoes via specific protein–protein interactions with the vacuolar sorting receptors. Supported by structural and mutagenesis studies, our work provides insights into how the sequence-specific information, or the vacuolar sorting determinant, on the storage proteins is recognized by the vacuolar sorting receptors for their targeting to the vacuoles. Insights gained into the rules of receptor–cargo recognition will be useful in engineering recombinant proteins for biotechnological applications of the protein storage vacuoles in seeds. In Arabidopsis, vacuolar sorting receptor isoform 1 (VSR1) sorts 12S globulins to the protein storage vacuoles during seed development. Vacuolar sorting is mediated by specific protein–protein interactions between VSR1 and the vacuolar sorting determinant located at the C terminus (ctVSD) on the cargo proteins. Here, we determined the crystal structure of the protease-associated domain of VSR1 (VSR1-PA) in complex with the C-terminal pentapeptide (468RVAAA472) of cruciferin 1, an isoform of 12S globulins. The 468RVA470 motif forms a parallel β-sheet with the switch III residues (127TMD129) of VSR1-PA, and the 471AA472 motif docks to a cradle formed by the cargo-binding loop (95RGDCYF100), making a hydrophobic interaction with Tyr99. The C-terminal carboxyl group of the ctVSD is recognized by forming salt bridges with Arg95. The C-terminal sequences of cruciferin 1 and vicilin-like storage protein 22 were sufficient to redirect the secretory red fluorescent protein (spRFP) to the vacuoles in Arabidopsis protoplasts. Adding a proline residue to the C terminus of the ctVSD and R95M substitution of VSR1 disrupted receptor–cargo interactions in vitro and led to increased secretion of spRFP in Arabidopsis protoplasts. How VSR1-PA recognizes ctVSDs of other storage proteins was modeled. The last three residues of ctVSD prefer hydrophobic residues because they form a hydrophobic cluster with Tyr99 of VSR1-PA. Due to charge–charge interactions, conserved acidic residues, Asp129 and Glu132, around the cargo-binding site should prefer basic residues over acidic ones in the ctVSD. The structural insights gained may be useful in targeting recombinant proteins to the protein storage vacuoles in seeds.
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Wu G, Jia Z, Ding K, Zheng H, Lu Y, Lin L, Peng J, Rao S, Wang A, Chen J, Yan F. Turnip mosaic virus co-opts the vacuolar sorting receptor VSR4 to promote viral genome replication in plants by targeting viral replication vesicles to the endosome. PLoS Pathog 2022; 18:e1010257. [PMID: 35073383 PMCID: PMC8812904 DOI: 10.1371/journal.ppat.1010257] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 02/03/2022] [Accepted: 01/07/2022] [Indexed: 12/27/2022] Open
Abstract
Accumulated experimental evidence has shown that viruses recruit the host intracellular machinery to establish infection. It has recently been shown that the potyvirus Turnip mosaic virus (TuMV) transits through the late endosome (LE) for viral genome replication, but it is still largely unknown how the viral replication vesicles labelled by the TuMV membrane protein 6K2 target LE. To further understand the underlying mechanism, we studied the involvement of the vacuolar sorting receptor (VSR) family proteins from Arabidopsis in this process. We now report the identification of VSR4 as a new host factor required for TuMV infection. VSR4 interacted specifically with TuMV 6K2 and was required for targeting of 6K2 to enlarged LE. Following overexpression of VSR4 or its recycling-defective mutant that accumulates in the early endosome (EE), 6K2 did not employ the conventional VSR-mediated EE to LE pathway, but targeted enlarged LE directly from cis-Golgi and viral replication was enhanced. In addition, VSR4 can be N-glycosylated and this is required for its stability and for monitoring 6K2 trafficking to enlarged LE. A non-glycosylated VSR4 mutant enhanced the dissociation of 6K2 from cis-Golgi, leading to the formation of punctate bodies that targeted enlarged LE and to more robust viral replication than with glycosylated VSR4. Finally, TuMV hijacks N-glycosylated VSR4 and protects VSR4 from degradation via the autophagy pathway to assist infection. Taken together, our results have identified a host factor VSR4 required for viral replication vesicles to target endosomes for optimal viral infection and shed new light on the role of N-glycosylation of a host factor in regulating viral infection. A key feature of the replication of positive-strand RNA viruses is the rearrangement of the host endomembrane system to produce a membranous replication organelle. Recent reports suggest that the late endosome (LE) serves as a replication site for the potyvirus Turnip mosaic virus (TuMV), but the mechanism(s) by which TuMV replication vesicles target LE are far from being fully elucidated. Identification of the host factors involved in this transport process could lead to new strategies to combat TuMV infection. In this report, we provide evidence that TuMV replication depends on functional vesicle transport from cis-Golgi to the enlarged LE pathway that is mediated by a specific VSR family member, VSR4, from Arabidopsis. Knock out of VSR4 impaired the targeting of TuMV replication vesicles to enlarged LE and suppressed viral infection, and this process depends on the specific interaction between VSR4 and the viral replication vesicle-forming protein 6K2. We also showed that N-glycosylation of VSR4 modulates the targeting of TuMV replication vesicles to enlarged LE and enhances viral infection, thus contributing to our understanding of how TuMV manipulates host factors in order to establish optimal infection. These results may have implications for the role of VSR in other positive-strand RNA viruses.
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Affiliation(s)
- Guanwei Wu
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Zhaoxing Jia
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Kaida Ding
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Hongying Zheng
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Yuwen Lu
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Lin Lin
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Jiejun Peng
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Shaofei Rao
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Aiming Wang
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada
| | - Jianping Chen
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
- * E-mail: (JC); (FY)
| | - Fei Yan
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Institute of Plant Virology, Ningbo University, Ningbo, China
- * E-mail: (JC); (FY)
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Carqueijeiro I, Sepúlveda LJ, Mosquera A, Payne R, Corbin C, Papon N, de Bernonville TD, Besseau S, Lanoue A, Glévarec G, Clastre M, St-Pierre B, Atehortùa L, Giglioli-Guivarc'h N, O'Connor SE, Oudin A, Courdavault V. Vacuole-Targeted Proteins: Ins and Outs of Subcellular Localization Studies. Methods Mol Biol 2018; 1789:33-54. [PMID: 29916070 DOI: 10.1007/978-1-4939-7856-4_4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Accurate and efficient demonstrations of protein localizations to the vacuole or tonoplast remain strict prerequisites to decipher the role of vacuoles in the whole plant cell biology and notably in defence processes. In this chapter, we describe a reliable procedure of protein subcellular localization study through transient transformations of Catharanthus roseus or onion cells and expression of fusions with fluorescent proteins allowing minimizing artefacts of targeting.
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Affiliation(s)
- Inês Carqueijeiro
- EA2106 "Biomolécules et Biotechnologies Végétales", UFR Sciences et Techniques, Université François-Rabelais de Tours, Tours, France
| | - Liuda J Sepúlveda
- EA2106 "Biomolécules et Biotechnologies Végétales", UFR Sciences et Techniques, Université François-Rabelais de Tours, Tours, France.,Laboratorio de Biotecnología, Sede de Investigación Universitaria, Universidad de Antioquia, Medellin, Colombia
| | - Angela Mosquera
- EA2106 "Biomolécules et Biotechnologies Végétales", UFR Sciences et Techniques, Université François-Rabelais de Tours, Tours, France.,Laboratorio de Biotecnología, Sede de Investigación Universitaria, Universidad de Antioquia, Medellin, Colombia
| | - Richard Payne
- Department of Biological Chemistry, The John Innes Centre, Norwich Research Park, Norwich, UK
| | - Cyrielle Corbin
- EA2106 "Biomolécules et Biotechnologies Végétales", UFR Sciences et Techniques, Université François-Rabelais de Tours, Tours, France
| | - Nicolas Papon
- EA3142 "Groupe d'Etude des Interactions Hôte-Pathogène", Université d'Angers, Angers, France
| | - Thomas Dugé de Bernonville
- EA2106 "Biomolécules et Biotechnologies Végétales", UFR Sciences et Techniques, Université François-Rabelais de Tours, Tours, France
| | - Sébastien Besseau
- EA2106 "Biomolécules et Biotechnologies Végétales", UFR Sciences et Techniques, Université François-Rabelais de Tours, Tours, France
| | - Arnaud Lanoue
- EA2106 "Biomolécules et Biotechnologies Végétales", UFR Sciences et Techniques, Université François-Rabelais de Tours, Tours, France
| | - Gaëlle Glévarec
- EA2106 "Biomolécules et Biotechnologies Végétales", UFR Sciences et Techniques, Université François-Rabelais de Tours, Tours, France
| | - Marc Clastre
- EA2106 "Biomolécules et Biotechnologies Végétales", UFR Sciences et Techniques, Université François-Rabelais de Tours, Tours, France
| | - Benoit St-Pierre
- EA2106 "Biomolécules et Biotechnologies Végétales", UFR Sciences et Techniques, Université François-Rabelais de Tours, Tours, France
| | - Lucia Atehortùa
- Laboratorio de Biotecnología, Sede de Investigación Universitaria, Universidad de Antioquia, Medellin, Colombia
| | - Nathalie Giglioli-Guivarc'h
- EA2106 "Biomolécules et Biotechnologies Végétales", UFR Sciences et Techniques, Université François-Rabelais de Tours, Tours, France
| | - Sarah E O'Connor
- Department of Biological Chemistry, The John Innes Centre, Norwich Research Park, Norwich, UK
| | - Audrey Oudin
- EA2106 "Biomolécules et Biotechnologies Végétales", UFR Sciences et Techniques, Université François-Rabelais de Tours, Tours, France
| | - Vincent Courdavault
- EA2106 "Biomolécules et Biotechnologies Végétales", UFR Sciences et Techniques, Université François-Rabelais de Tours, Tours, France.
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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.
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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,
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Occhialini A, Marc-Martin S, Gouzerh G, Hillmer S, Neuhaus JM. RMR (Receptor Membrane RING-H2) type 1 and 2 show different promoter activities and subcellular localizations in Arabidopsis thaliana. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2018; 266:9-18. [PMID: 29241571 DOI: 10.1016/j.plantsci.2017.10.007] [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: 06/08/2017] [Revised: 08/27/2017] [Accepted: 10/14/2017] [Indexed: 05/02/2023]
Abstract
Soluble vacuolar proteins reach their compartments of final accumulation through the binding with specific transmembrane cargo receptors. In Arabidopsis thaliana two different families of receptors have been characterized. The AtVSRs (Vacuolar Sorting Receptor), which are known to be involved in the protein sorting to lytic vacuoles (LV), and the AtRMRs (Receptor Membrane RING-H2), for which there is less evidence for a role in the traffic to the protein storage vacuole (PSV). In this study we investigated the localization and tissue expression of two RMRs (AtRMR1 and 2) in their species of origin, A. thaliana. Our experiments using leaf protoplasts and transgenic plants supported previous results of subcellular localization in Nicotiana benthamiana that visualized AtRMR1 and 2 in the cisternae of endoplasmic reticulum (ER) and in the trans-Golgi network (TGN), respectively. The promoter activities of AtRMR1 and AtRMR2 detected in transgenic A. thaliana lines suggest that the expression of these two receptors only partially overlap in some organs and tissues. These results suggest that AtRMR1 and 2 are not functionally redundant, but could also interact and participate in the same cellular process in tissues with an overlapping expression.
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Affiliation(s)
- Alessandro Occhialini
- Department of Food Science, University of Tennessee, Food Safety and Processing Building, 2600 River Dr., Knoxville, TN 37996, USA; Institute of Biology, Laboratory of Cell and Molecular Biology, University of Neuchâtel, Rue Emile-Argand 11, CH-2000 Neuchâtel, Switzerland.
| | - Sophie Marc-Martin
- Institute of Biology, Laboratory of Cell and Molecular Biology, University of Neuchâtel, Rue Emile-Argand 11, CH-2000 Neuchâtel, Switzerland
| | - Guillaume Gouzerh
- Institute of Biology, Laboratory of Cell and Molecular Biology, University of Neuchâtel, Rue Emile-Argand 11, CH-2000 Neuchâtel, Switzerland
| | - Stefan Hillmer
- Electron Microscopy Core Facility, University of Heidelberg, Im Neuenheimer Feld 345, 69120 Heidelberg, Germany
| | - Jean-Marc Neuhaus
- Institute of Biology, Laboratory of Cell and Molecular Biology, University of Neuchâtel, Rue Emile-Argand 11, CH-2000 Neuchâtel, Switzerland.
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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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Le Signor C, Aimé D, Bordat A, Belghazi M, Labas V, Gouzy J, Young ND, Prosperi JM, Leprince O, Thompson RD, Buitink J, Burstin J, Gallardo K. Genome-wide association studies with proteomics data reveal genes important for synthesis, transport and packaging of globulins in legume seeds. THE NEW PHYTOLOGIST 2017; 214:1597-1613. [PMID: 28322451 DOI: 10.1111/nph.14500] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 01/27/2017] [Indexed: 05/25/2023]
Abstract
Improving nutritional seed quality is an important challenge in grain legume breeding. However, the genes controlling the differential accumulation of globulins, which are major contributors to seed nutritional value in legumes, remain largely unknown. We combined a search for protein quantity loci with genome-wide association studies on the abundance of 7S and 11S globulins in seeds of the model legume species Medicago truncatula. Identified genomic regions and genes carrying polymorphisms linked to globulin variations were then cross-compared with pea (Pisum sativum), leading to the identification of candidate genes for the regulation of globulin abundance in this crop. Key candidates identified include genes involved in transcription, chromatin remodeling, post-translational modifications, transport and targeting of proteins to storage vacuoles. Inference of a gene coexpression network of 12 candidate transcription factors and globulin genes revealed the transcription factor ABA-insensitive 5 (ABI5) as a highly connected hub. Characterization of loss-of-function abi5 mutants in pea uncovered a role for ABI5 in controlling the relative abundance of vicilin, a sulfur-poor 7S globulin, in pea seeds. This demonstrates the feasibility of using genome-wide association studies in M. truncatula to reveal genes that can be modulated to improve seed nutritional value.
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Affiliation(s)
- Christine Le Signor
- Agroécologie, AgroSup Dijon, Institut National de la Recherche Agronomique (INRA), Université Bourgogne Franche-Comté, 21000, Dijon, France
| | - Delphine Aimé
- Agroécologie, AgroSup Dijon, Institut National de la Recherche Agronomique (INRA), Université Bourgogne Franche-Comté, 21000, Dijon, France
| | - Amandine Bordat
- Unité Mixte de Recherche (UMR) 1332 Biologie du Fruit et Pathologie, INRA, 33882, Villenave d'Ornon, France
| | - Maya Belghazi
- UMR 7286 - CRN2M, Centre d'Analyses Protéomiques de Marseille, CNRS, Aix-Marseille Université, Marseille, France
| | - Valérie Labas
- INRA, UMR85 Physiologie de la Reproduction et des Comportements-Centre National de la Recherche Scientifique (CNRS) UMR 7247-Université François Rabelais-Institut Français du Cheval et de l'Equitation, Laboratoire de Spectrométrie de Masse, Plate-forme d'Analyse Intégrative des Biomolécules, 37380, Nouzilly, France
| | - Jérôme Gouzy
- Laboratoire des Interactions Plantes-Microorganismes (LIPM), CNRS, INRA, Université de Toulouse, Castanet-Tolosan, France
| | - Nevin D Young
- Department of Plant Pathology, University of Minnesota, St Paul, MN, 55108, USA
| | - Jean-Marie Prosperi
- Genetic Improvement and Adaptation of Mediterranean and Tropical Plants (AGAP), INRA, Centre de coopération internationale en recherche agronomique pour le développement (CIRAD), Montpellier Supagro, 34060, Montpellier, France
| | - Olivier Leprince
- Institut de recherche en horticulture et semences (IRHS), INRA, Agrocampus-Ouest, Université d'Angers, SFR 4207 QuaSaV, 49071, Beaucouzé, France
| | - Richard D Thompson
- Agroécologie, AgroSup Dijon, Institut National de la Recherche Agronomique (INRA), Université Bourgogne Franche-Comté, 21000, Dijon, France
| | - Julia Buitink
- Institut de recherche en horticulture et semences (IRHS), INRA, Agrocampus-Ouest, Université d'Angers, SFR 4207 QuaSaV, 49071, Beaucouzé, France
| | - Judith Burstin
- Agroécologie, AgroSup Dijon, Institut National de la Recherche Agronomique (INRA), Université Bourgogne Franche-Comté, 21000, Dijon, France
| | - Karine Gallardo
- Agroécologie, AgroSup Dijon, Institut National de la Recherche Agronomique (INRA), Université Bourgogne Franche-Comté, 21000, Dijon, France
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Ovesná J, Mitrová K, Kučera L. Garlic (A. sativum L.) alliinase gene family polymorphism reflects bolting types and cysteine sulphoxides content. BMC Genet 2015; 16:53. [PMID: 25997498 PMCID: PMC4440563 DOI: 10.1186/s12863-015-0214-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 05/11/2015] [Indexed: 02/02/2023] Open
Abstract
Background Alliinase is an important enzyme occurring in Allium species that converts precursors of sulfuric compounds, cysteine sulfoxides into a biologically active substance termed allicin. Allicin facilitates garlic defense against pests and produces health-promoting compounds. Alliinase is encoded by members of a multigene family that has not yet been sufficiently characterized, namely with regard to the copy numbers occurring within the genome and the polymorphisms among the family members. Results We cloned 45 full-length alliinase amplicons of cultivar (cv.) Jovan. Sequence analyses revealed nine different sequence variants (SVs), confirming the multilocus nature of this gene family. Several mutations in exons, mainly occurring in the first exon coding for vacuolar signal peptide, were found. These results enabled us to identify sequences with putatively modified vacuole-targeting abilities. We found additional sequence variants using partial amplicons. We estimated that the minimum number of gene copies in the diploid genome of the investigated cultivar was fourteen. We obtained similar results for another three cultivars, which differed in bolting type and place of origin. The further identification of high degree of polymorphisms in the intron regions allowed us to develop a specific polymerase chain reaction assay capable to capture intron length polymorphism (ILP). This assay was used to screen 131 additional accessions. Polymorphic data were used for cluster analysis, which separated the bolting and non-bolting garlic types and those with high cysteine-sulfoxide contents in a similar way as AFLP analysis in previous study. These newly developed markers can be further applied for the selection of desirable garlic genotypes. Conclusions Detailed analysis of sequences confirmed multigenic nature of garlic alliinase. Intron and exon polymorphism analysis generated similar results as whole genome variability assessed previously by AFLP. Detected polymorphism is thus also associated with cysteine-sulphoxide content in individual genotypes. ILP markers capable to detect intron polymorphisms were newly developed. Developed markers could be applied in garlic breeding. Higher genetic variability found in bolting genotypes may indicates longer period of their sexual propagation in comparison with nonbolting genotypes. Electronic supplementary material The online version of this article (doi:10.1186/s12863-015-0214-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jaroslava Ovesná
- Crop Research Institute, Drnovská 507/73, 161 06, Prague-Ruzyně, Czech Republic.
| | - Katarína Mitrová
- Crop Research Institute, Drnovská 507/73, 161 06, Prague-Ruzyně, Czech Republic.
| | - Ladislav Kučera
- Crop Research Institute, Drnovská 507/73, 161 06, Prague-Ruzyně, Czech Republic.
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Hegedus DD, Coutu C, Harrington M, Hope B, Gerbrandt K, Nikolov I. Multiple internal sorting determinants can contribute to the trafficking of cruciferin to protein storage vacuoles. PLANT MOLECULAR BIOLOGY 2015; 88:3-20. [PMID: 25702284 DOI: 10.1007/s11103-015-0297-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 02/13/2015] [Indexed: 06/04/2023]
Abstract
Trafficking of seed storage proteins to protein storage vacuoles is mediated by carboxy terminal and internal sorting determinants (ISDs). Protein modelling was used to identify candidate ISDs residing near surface-exposed regions in Arabidopsis thaliana cruciferin A (AtCruA). These were verified by AtCruA fusion to yellow fluorescent protein (YFP) and expression in developing embryos of A. thaliana. As the presence of endogenous cruciferin was found to mask the effects of weaker ISDs, experiments were conducted in a line that was devoid of cruciferin. In total, nine ISDs were discovered and a core determinant defined using a series of alanine scanning and deletion mutant variants. Coupling of functional data from AtCruA ISD-YFP fusions with statistical analysis of the physiochemical properties of analogous regions from several 11/12S globulins revealed that cruciferin ISDs likely adhere to the following rules: (1) ISDs are adjacent to or within hydrophilic, surface-exposed regions that serve to present them on the protein's surface; (2) ISDs generally have a hydrophobic character; (3) ISDs tend to have Leu or Ile residues at their core; (4) ISDs are approximately eight amino acids long with the physiochemical consensus [hydrophobic][preferably charged][small or hydrophobic, but not tiny][IL][polar, preferably charged][small, but not charged][hydrophobic, not charged, preferably not polar][hydrophobic, not tiny, preferably not polar]. Microscopic evidence is also presented for the presence of an interconnected protein storage vacuolar network in embryo cells, rather than discreet, individual vacuoles.
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Affiliation(s)
- Dwayne D Hegedus
- Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK, S7N 0X2, Canada,
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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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11
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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.
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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
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12
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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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13
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Delivering of proteins to the plant vacuole--an update. Int J Mol Sci 2014; 15:7611-23. [PMID: 24802873 PMCID: PMC4057694 DOI: 10.3390/ijms15057611] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 04/21/2014] [Accepted: 04/22/2014] [Indexed: 01/17/2023] Open
Abstract
Trafficking of soluble cargo to the vacuole is far from being a closed issue as it can occur by different routes and involve different intermediates. The textbook view of proteins being sorted at the post-Golgi level to the lytic vacuole via the pre-vacuole or to the protein storage vacuole mediated by dense vesicles is now challenged as novel routes are being disclosed and vacuoles with intermediate characteristics described. The identification of Vacuolar Sorting Determinants is a key signature to understand protein trafficking to the vacuole. Despite the long established vacuolar signals, some others have been described in the last few years, with different properties that can be specific for some cells or some types of vacuoles. There are also reports of proteins having two different vacuolar signals and their significance is questionable: a way to increase the efficiency of the sorting or different sorting depending on the protein roles in a specific context? Along came the idea of differential vacuolar sorting, suggesting a possible specialization of the trafficking pathways according to the type of cell and specific needs. In this review, we show the recent advances in the field and focus on different aspects of protein trafficking to the vacuoles.
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14
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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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15
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Xiang L, Van den Ende W. Trafficking of plant vacuolar invertases: from a membrane-anchored to a soluble status. Understanding sorting information in their complex N-terminal motifs. PLANT & CELL PHYSIOLOGY 2013; 54:1263-1277. [PMID: 23737500 DOI: 10.1093/pcp/pct075] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Vacuolar invertases (VIs) are highly expressed in young tissues and organs. They may have a substantial regulatory influence on whole-plant metabolism as well as on photosynthetic efficiency. Therefore, they are emerging as potentially interesting biotechnological targets to increase plant biomass production, especially under stress. On the one hand, VIs are well known as soluble and extractable proteins. On the other hand, they contain complex N-terminal propeptide (NTPP) regions with a basic region (BR) and a transmembrane domain (TMD). Here we analyzed in depth the Arabidopsis thaliana VI2 (AtVI2) NTPP by mutagenesis. It was found that correct sorting to the lytic vacuole (LV) depends on the presence of intact dileucine (SSDALLPIS), BR (RRRR) and TMD motifs. AtVI2 remains inserted into membranes on its way to the LV, and the classical sorting pathway (endoplasmic reticulum→Golgi→LV) is followed. However, our data suggest that VIs might follow an alternative, adaptor protein 3 (AP3)-dependent route as well. Membrane-anchored transport and a direct recognition of the dileucine motif in the NTPP of VIs might have evolved as a simple and more efficient sorting mechanism as compared with the vacuolar sorting receptor 1/binding protein of 80 kDa (VSR1/BP80)-dependent sorting mechanism followed by those proteins that travel to the vacuole as soluble proteins.
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Affiliation(s)
- Li Xiang
- Biology Department, Laboratory for Molecular Plant Biology, KU Leuven, Kasteelpark Arenberg 31, Box 2434, B-3001 Heverlee, Belgium
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16
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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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17
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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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18
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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.
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Affiliation(s)
- Verena Ibl
- Department for Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Muthgasse 18, 1190, Vienna, Austria
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19
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Jung C, Lee GJ, Jang M, Lee M, Lee J, Kang H, Sohn EJ, Hwang I. Identification of sorting motifs of AtβFruct4 for trafficking from the ER to the vacuole through the Golgi and PVC. Traffic 2011; 12:1774-92. [PMID: 21899678 DOI: 10.1111/j.1600-0854.2011.01276.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Although much is known about the molecular mechanisms involved in transporting soluble proteins to the central vacuole, the mechanisms governing the trafficking of membrane proteins remain largely unknown. In this study, we investigated the mechanism involved in targeting the membrane protein, AtβFructosidase 4 (AtβFruct4), to the central vacuole in protoplasts. AtβFruct4 as a green fluorescent protein (GFP) fusion protein was transported as a membrane protein during transit from the endoplasmic reticulum (ER) through the Golgi apparatus and the prevacuolar compartment (PVC). The N-terminal cytosolic domain of AtβFruct4 was sufficient for transport from the ER to the central vacuole and contained sequence motifs required for trafficking. The sequence motifs, LL and PI, were found to be critical for ER exit, while the EEE and LCPYTRL sequence motifs played roles in trafficking primarily from the trans Golgi network (TGN) to the PVC and from the PVC to the central vacuole, respectively. In addition, actin filaments and AtRabF2a, a Rab GTPase, played critical roles in vacuolar trafficking at the TGN and PVC, respectively. On the basis of these results, we propose that the vacuolar trafficking of AtβFruct4 depends on multiple sequence motifs located at the N-terminal cytoplasmic domain that function as exit and/or sorting signals in different stages during the trafficking process.
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Affiliation(s)
- Chanjin Jung
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
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20
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Scabone CM, Frigerio L, Petruccelli S. A fluorescent reporter protein containing AtRMR1 domains is targeted to the storage and central vacuoles in Arabidopsis thaliana and tobacco leaf cells. PLANT CELL REPORTS 2011; 30:1823-33. [PMID: 21611741 DOI: 10.1007/s00299-011-1089-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Accepted: 05/09/2011] [Indexed: 05/15/2023]
Abstract
To develop a new strategy to target recombinant proteins to the vacuolar storage system in transgenic plants, the ability of the transmembrane and cytosolic domains of Arabidopsis receptor homology-transmembrane-RING H2-1 (AtRMR1) was evaluated. A secreted version of RFP (secRFP) and a fusion of it to the transmembrane and cytosolic domains of AtRMR1 (RFP-TMCT) were produced and studied both in transient and stable expression assays. Transient expression in leaves of Nicotiana tabacum showed that secRFP is secreted to the apoplast while its fusion to TMCT of AtRMR1 is sufficient to prevent secretion of the reporter. In tobacco leaves, RFP-TMCT reporter showed an endoplasmic reticulum pattern in early expression stages while in late expression stages, it was found in the vacuolar lumen. For the first time, the role of TM and CT domains of AtRMR1 in stable expression in Arabidopsis thaliana is presented; the fusion of TMCT to secRFP is sufficient to sort RFP to the lumen of the central vacuoles in leaves and roots and to the lumen of PSV in cotyledons of mature embryos. In addition, biochemical studies performed in extract from transgenic plants showed that RFP-TMCT is an integral membrane protein. Full-length RFP-TMCT was also found in the vacuolar lumen, suggesting internalization into destination vacuole. Not colocalization of RFP-TMCT with tonoplast and plasma membrane markers were observed. This membrane vacuolar determinant sorting signal could be used for future application in molecular pharming as an alternative means to sort proteins of interest to vacuoles.
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Affiliation(s)
- Camila María Scabone
- Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA), CCT-La Plata CONICET, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de la Plata, CC553, 1900, La Plata, Argentina
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Oomen RJFJ, Séveno-Carpentier E, Ricodeau N, Bournaud C, Conéjéro G, Paris N, Berthomieu P, Marquès L. Plant defensin AhPDF1.1 is not secreted in leaves but it accumulates in intracellular compartments. THE NEW PHYTOLOGIST 2011; 192:140-150. [PMID: 21679189 DOI: 10.1111/j.1469-8137.2011.03792.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
• Apart from their antifungal role, plant defensins have recently been shown to be involved in abiotic stress tolerance or in inhibition of root growth when added in plant culture medium. We studied the subcellular localization of these proteins, which may account for these different roles. • Stable and transient expression of AhPDF1.1::GFP (green fluorescent protein) fusion proteins were analysed in yeast and plants. Functional tests established that the GFP tag did not alter the action of the defensin. Subcellular localization of AhPDF1.1 was characterized: by imaging AhPDF1.1::GFP together with organelle markers; and by immunolabelling AhPDF1.1 in Arabidopsis halleri and Arabidopsis thaliana leaves using a polyclonal serum. • All our independent approaches demonstrated that AhPDF1.1 is retained in intracellular compartments on the way to the lytic vacuole, instead of being addressed to the apoplasm. • These findings challenge the commonly accepted idea of secretion of defensins. The subcellular localization highlighted in this study could partly explain the dual role of plant defensins on plant cells and is of major importance to unravel the mechanisms of action of these proteins at the cellular level.
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Affiliation(s)
- Ronald J F J Oomen
- Laboratoire de Biochimie & Physiologie Moléculaire des Plantes, UMR Université Montpellier 2, CNRS, INRA, Montpellier SupAgro, 2 place Viala, F-34060 Montpellier Cedex 02, France
| | - Emilie Séveno-Carpentier
- Laboratoire de Biochimie & Physiologie Moléculaire des Plantes, UMR Université Montpellier 2, CNRS, INRA, Montpellier SupAgro, 2 place Viala, F-34060 Montpellier Cedex 02, France
| | - Nicolas Ricodeau
- Laboratoire de Biochimie & Physiologie Moléculaire des Plantes, UMR Université Montpellier 2, CNRS, INRA, Montpellier SupAgro, 2 place Viala, F-34060 Montpellier Cedex 02, France
| | - Caroline Bournaud
- Laboratoire de Biochimie & Physiologie Moléculaire des Plantes, UMR Université Montpellier 2, CNRS, INRA, Montpellier SupAgro, 2 place Viala, F-34060 Montpellier Cedex 02, France
| | - Geneviève Conéjéro
- Laboratoire de Biochimie & Physiologie Moléculaire des Plantes, UMR Université Montpellier 2, CNRS, INRA, Montpellier SupAgro, 2 place Viala, F-34060 Montpellier Cedex 02, France
| | - Nadine Paris
- Laboratoire de Biochimie & Physiologie Moléculaire des Plantes, UMR Université Montpellier 2, CNRS, INRA, Montpellier SupAgro, 2 place Viala, F-34060 Montpellier Cedex 02, France
| | - Pierre Berthomieu
- Laboratoire de Biochimie & Physiologie Moléculaire des Plantes, UMR Université Montpellier 2, CNRS, INRA, Montpellier SupAgro, 2 place Viala, F-34060 Montpellier Cedex 02, France
| | - Laurence Marquès
- Laboratoire de Biochimie & Physiologie Moléculaire des Plantes, UMR Université Montpellier 2, CNRS, INRA, Montpellier SupAgro, 2 place Viala, F-34060 Montpellier Cedex 02, France
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Shen Y, Wang J, Ding Y, Lo SW, Gouzerh G, Neuhaus JM, Jiang L. The rice RMR1 associates with a distinct prevacuolar compartment for the protein storage vacuole pathway. MOLECULAR PLANT 2011; 4:854-68. [PMID: 21493745 DOI: 10.1093/mp/ssr025] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Transport of vacuolar proteins from Golgi apparatus or trans-Golgi network (TGN) to vacuoles is a receptor-mediated process via an intermediate membrane-bound prevacuolar compartment (PVC) in plant cells. Both vacuolar sorting receptor (VSR) and receptor homology region-transmembrane domain-RING-H2 (RMR) proteins have been shown to function in transporting storage proteins to protein storage vacuole (PSV), but little is known about the nature of the PVC for the PSV pathway. Here, we use the rice RMR1 (OsRMR1) as a probe to study the PSV pathway in plants. Immunogold electron microscopy (EM) with specific OsRMR1 antibodies showed that OsRMR1 proteins were found in the Golgi apparatus, TGN, and a distinct organelle with characteristics of PVC in both rice culture cells and developing rice seeds, as well as the protein body type II (PBII) or PSV in developing rice seeds. This organelle, also found in both tobacco BY-2 and Arabidopsis suspension cultured cells, is morphologically distinct from the VSR-positive multivesicular lytic PVC or multivesicular body (MVB) and thus represent a PVC for the PSV pathway that we name storage PVC (sPVC). Further in vivo and in vitro interaction studies using truncated OsRMR1 proteins secreted into the culture media of transgenic BY-2 suspension cells demonstrated that OsRMR1 functions as a sorting receptor in transporting vicilin-like storage proteins.
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Affiliation(s)
- Yun Shen
- 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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Wang H, Zhuang XH, Hillmer S, Robinson DG, Jiang LW. Vacuolar sorting receptor (VSR) proteins reach the plasma membrane in germinating pollen tubes. MOLECULAR PLANT 2011; 4:845-53. [PMID: 21430175 DOI: 10.1093/mp/ssr011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Vacuolar sorting receptors (VSRs) are type I integral membrane proteins that mediate the vacuolar transport of soluble cargo proteins via prevacuolar compartments (PVCs) in plants. Confocal immunofluorescent and immunogold Electron Microscope (EM) studies have localized VSRs to PVCs or multivesicular bodies (MVBs) and trans-Golgi network (TGN) in various plant cell types, including suspension culture cells, root cells, developing and germinating seeds. Here, we provide evidence that VSRs reach plasma membrane (PM) in growing pollen tubes. Both immunofluorescent and immunogold EM studies with specific VSR antibodies show that, in addition to the previously demonstrated PVC/MVB localization, VSRs also localize to PM in lily and tobacco pollen tubes prepared from chemical fixation or high-pressure freezing/frozen substitution. Such a PM localization suggests an additional role of VSR proteins in mediating protein transport to PM and endocytosis in growing pollen tubes. Using a high-speed Spinning Disc Confocal Microscope, the possible fusion between VSR-positive PVC organelles and the PM was also observed in living tobacco pollen tubes transiently expressing the PVC reporter GFP-VSR. In contrast, the lack of a prominent PM localization of GFP-VSR in living pollen tubes may be due to the highly dynamic situation of vesicular transport in this fast-growing cell type.
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Affiliation(s)
- Hao Wang
- 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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24
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Köthke S, Köck M. The Solanum lycopersicum RNaseLER is a class II enzyme of the RNase T2 family and shows preferential expression in guard cells. JOURNAL OF PLANT PHYSIOLOGY 2011; 168:840-7. [PMID: 21237531 DOI: 10.1016/j.jplph.2010.11.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Revised: 10/12/2010] [Accepted: 11/08/2010] [Indexed: 05/30/2023]
Abstract
Ribonucleases (RNases) occur in different gene families, functioning in RNA processing and degradation. In this study, we report on cloning and characterization of RNaseLER, the first class II gene of the RNase T2 family in tomato (Solanum lycopersicum). The family also includes the class I members RNaseLE and RNaseLX, and the class III group of S-RNases acting in self incompatibility. The RNaseLER gene was cloned by polymerase chain reaction (PCR)-assisted methods. Structural analyses of RNaseLER and homologous genes revealed unique key features of class II RNase T2 genes. RNaseLER is a single copy gene in tomato and codes for a primary protein of 260 amino acids. Subcellular localization analyzed with a RNaseLER-eYFP fusion protein and co-localization experiments revealed an intracellular accumulation in the endoplasmic reticulum. Transgenic Nicotiana benthamiana plants carrying the uidA reporter gene under the control of a 900-bp RNaseLER promoter sequence express the reporter gene predominantly in guard cells and trichomes. This previously unknown spatial expression of a RNase T2 gene is consistent with ubiquitous detection of low RNaseLER transcript abundances in almost all parts of tomato plants. As revealed by quantitative real-time RT-PCR analysis treatments with abscisic acid, ethylene or other abiotic and biotic stress factors did not affect RNaseLER expression significantly. Unlike tomato class I genes, RNaseLER represents a constitutively expressed gene with a cell-specific role in stomata and trichomes and no involvement in stress responses.
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Affiliation(s)
- Sabine Köthke
- Martin-Luther-Universität Halle-Wittenberg, Biozentrum, Weinbergweg 22, D-06120 Halle, Germany
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25
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Wang H, Rogers JC, Jiang L. Plant RMR proteins: unique vacuolar sorting receptors that couple ligand sorting with membrane internalization. FEBS J 2010; 278:59-68. [PMID: 21078125 DOI: 10.1111/j.1742-4658.2010.07923.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In receptor-mediated sorting of soluble protein ligands in the endomembrane system of eukaryotic cells, three completely different receptor proteins for mammalian (mannose 6-phosphate receptor), yeast (Vps10p) and plant cells (vacuolar sorting receptor; VSR) have in common the features of pH-dependent ligand binding and receptor recycling. In striking contrast, the plant receptor homology-transmembrane-RING-H2 (RMR) proteins serve as sorting receptors to a separate type of vacuole, the protein storage vacuole, but do not recycle, and their trafficking pathway results in their internalization into the destination vacuole. Even though plant RMR proteins share high sequence similarity with the best-characterized mammalian PA-TM-RING family proteins, these two families of proteins appear to play distinctly different roles in plant and animal cells. Thus, this minireview focuses on this unique sorting mechanism and traffic of RMR proteins via dense vesicles in various plant cell types.
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Affiliation(s)
- Hao Wang
- Department of Biology, Centre for Cell and Developmental Biology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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26
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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.
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27
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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.
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Affiliation(s)
- Silke Niemes
- Department of Cell Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, Germany
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28
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Wang H, Tse YC, Law AHY, Sun SSM, Sun YB, Xu ZF, Hillmer S, Robinson DG, Jiang L. Vacuolar sorting receptors (VSRs) and secretory carrier membrane proteins (SCAMPs) are essential for pollen tube growth. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 61:826-38. [PMID: 20030753 DOI: 10.1111/j.1365-313x.2009.04111.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Vacuolar sorting receptors (VSRs) are type-I integral membrane proteins that mediate biosynthetic protein traffic in the secretory pathway to the vacuole, whereas secretory carrier membrane proteins (SCAMPs) are type-IV membrane proteins localizing to the plasma membrane and early endosome (EE) or trans-Golgi network (TGN) in the plant endocytic pathway. As pollen tube growth is an extremely polarized and highly dynamic process, with intense anterograde and retrograde membrane trafficking, we have studied the dynamics and functional roles of VSR and SCAMP in pollen tube growth using lily (Lilium longiflorum) pollen as a model. Using newly cloned lily VSR and SCAMP cDNA (termed LIVSR and LISCAMP, respectively), as well as specific antibodies against VSR and SCAMP1 as tools, we have demonstrated that in growing lily pollen tubes: (i) transiently expressed GFP-VSR/GFP-LIVSR is located throughout the pollen tubes, excepting the apical clear-zone region, whereas GFP-LISCAMP is mainly concentrated in the tip region; (ii) VSRs are localized to the multivesicular body (MVB) and vacuole, whereas SCAMPs are localized to apical endocytic vesicles, TGN and vacuole; and (iii) microinjection of VSR or SCAMP antibodies and LlVSR small interfering RNAs (siRNAs) significantly reduced the growth rate of the lily pollen tubes. Taken together, both VSR and SCAMP are required for pollen tube growth, probably working together in regulating protein trafficking in the secretory and endocytic pathways, which need to be coordinated in order to support pollen tube elongation.
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Affiliation(s)
- Hao Wang
- Department of Biology, Centre for Cell and Developmental Biology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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29
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Limpens E, Ivanov S, van Esse W, Voets G, Fedorova E, Bisseling T. Medicago N2-fixing symbiosomes acquire the endocytic identity marker Rab7 but delay the acquisition of vacuolar identity. THE PLANT CELL 2009; 21:2811-28. [PMID: 19734435 PMCID: PMC2768938 DOI: 10.1105/tpc.108.064410] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Rhizobium bacteria form N(2)-fixing organelles, called symbiosomes, inside the cells of legume root nodules. The bacteria are generally thought to enter the cells via an endocytosis-like process. To examine this, we studied the identity of symbiosomes in relation to the endocytic pathway. We show that in Medicago truncatula, the small GTPases Rab5 and Rab7 are endosomal membrane identity markers, marking different (partly overlapping) endosome populations. Although symbiosome formation is considered to be an endocytosis-like process, symbiosomes do not acquire Rab5 at any stage during their development, nor do they accept the trans-Golgi network identity marker SYP4, presumed to mark early endosomes in plants. By contrast, the endosomal marker Rab7 does occur on symbiosomes from an early stage of development when they have stopped dividing up to the senescence stage. However, the symbiosomes do not acquire vacuolar SNAREs (SYP22 and VTI11) until the onset of their senescence. By contrast, symbiosomes acquire the plasma membrane SNARE SYP132 from the start of symbiosome formation throughout their development. Therefore, symbiosomes appear to be locked in a unique SYP132- and Rab7-positive endosome stage and the delay in acquiring (lytic) vacuolar identity (e.g., vacuolar SNAREs) most likely ensures their survival and maintenance as individual units.
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Affiliation(s)
- Erik Limpens
- Laboratory of Molecular Biology, Graduate School of Experimental Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Sergey Ivanov
- Laboratory of Molecular Biology, Graduate School of Experimental Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
- K.A. Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow 127392, Russia
| | - Wilma van Esse
- Laboratory of Molecular Biology, Graduate School of Experimental Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Guido Voets
- Laboratory of Molecular Biology, Graduate School of Experimental Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Elena Fedorova
- Laboratory of Molecular Biology, Graduate School of Experimental Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
- K.A. Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow 127392, Russia
| | - Ton Bisseling
- Laboratory of Molecular Biology, Graduate School of Experimental Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
- Address correspondence to
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30
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Sharma AK, Sharma MK. Plants as bioreactors: Recent developments and emerging opportunities. Biotechnol Adv 2009; 27:811-832. [PMID: 19576278 PMCID: PMC7125752 DOI: 10.1016/j.biotechadv.2009.06.004] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2009] [Revised: 06/15/2009] [Accepted: 06/16/2009] [Indexed: 12/18/2022]
Abstract
In recent years, the use of plants as bioreactors has emerged as an exciting area of research and significant advances have created new opportunities. The driving forces behind the rapid growth of plant bioreactors include low production cost, product safety and easy scale up. As the yield and concentration of a product is crucial for commercial viability, several strategies have been developed to boost up protein expression in transgenic plants. Augmenting tissue-specific transcription, elevating transcript stability, tissue-specific targeting, translation optimization and sub-cellular accumulation are some of the strategies employed. Various kinds of products that are currently being produced in plants include vaccine antigens, medical diagnostics proteins, industrial and pharmaceutical proteins, nutritional supplements like minerals, vitamins, carbohydrates and biopolymers. A large number of plant-derived recombinant proteins have reached advanced clinical trials. A few of these products have already been introduced in the market.
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Affiliation(s)
- Arun K Sharma
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi 110021, India.
| | - Manoj K Sharma
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi 110021, India
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31
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Phan NQ, Kim SJ, Bassham DC. Overexpression of Arabidopsis sorting nexin AtSNX2b inhibits endocytic trafficking to the vacuole. MOLECULAR PLANT 2008; 1:961-976. [PMID: 19825596 DOI: 10.1093/mp/ssn057] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Sorting nexins are conserved proteins that function in vesicular trafficking and contain a characteristic phox homology (PX) domain. Here, we characterize the ubiquitously expressed Arabidopsis thaliana sorting nexin AtSNX2b. Sub-cellular fractionation studies indicate that AtSNX2b is peripherally associated with membranes. The AtSNX2b PX domain binds to phosphatidylinositol 3-phosphate in vitro and this association is required for the localization of GFP-AtSNX2b to punctate structures in vivo, identified as the trans-Golgi network, prevacuolar compartment and endosomes. Overexpression of GFP-tagged AtSNX2b produces enlarged GFP-labeled compartments that can also be labeled by the endocytic tracer FM4-64. Endocytic trafficking of FM4-64 to the vacuole is arrested in these GFP-AtSNX2b compartments, and similar FM4-64-accumulating compartments are seen upon overexpression of untagged AtSNX2b. This suggests that exit of membrane components from these enlarged or aggregated endosomes is inhibited. Vacuolar proteins containing an N-terminal propeptide, but not those with a C-terminal propeptide, are also present in these enlarged compartments. We hypothesize that AtSNX2b is involved in vesicular trafficking from endosomes to the vacuole.
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Affiliation(s)
- Nguyen Q Phan
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
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32
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Lam SK, Cai Y, Hillmer S, Robinson DG, Jiang L. SCAMPs highlight the developing cell plate during cytokinesis in tobacco BY-2 cells. PLANT PHYSIOLOGY 2008; 147:1637-45. [PMID: 18508957 PMCID: PMC2492649 DOI: 10.1104/pp.108.119925] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Accepted: 05/19/2008] [Indexed: 05/17/2023]
Abstract
We previously demonstrated that rice (Oryza sativa) SECRETORY CARRIER MEMBRANE PROTEIN1 (OsSCAMP1)-yellow fluorescent protein in transgenic tobacco (Nicotiana tabacum) Bright Yellow-2 cells locates to the plasma membrane and to motile punctate structures, which represent the trans-Golgi network/early endosome and are tubular-vesicular in nature. Here, we now show that SCAMPs are diverted to the cell plate during cytokinesis dividing Bright Yellow-2 cells. As cells progress from metaphase to cytokinesis, punctate OsSCAMP1-labeled structures begin to collect in the future division plane. Together with the internalized endosomal marker FM4-64, they then become incorporated into the cell plate as it forms and expands. This was confirmed by immunogold electron microscopy. We also monitored for the Golgi apparatus and the prevacuolar compartment (PVC)/multivesicular body. Golgi stacks tend to accumulate in the vicinity of the division plane, but the signals are clearly separate to the cell plate. The situation with the PVC (labeled by green fluorescent protein-BP-80) is not so clear. Punctate BP-80 signals are seen at the advancing periphery of the cell plate, which was confirmed by immunogold electron microscopy. Specific but weak labeling was observed in the cell plate, but no evidence for a fusion of the PVC/multivesicular body with the cell plate could be obtained. Our data, therefore, support the notion that cell plate formation is mainly a secretory process involving mass incorporation of domains of the trans-Golgi network/early endosome membrane. We regard the involvement of multivesicular late endosomes in this process to be equivocal.
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Affiliation(s)
- Sheung Kwan Lam
- Department of Biology and Molecular Biotechnology Program, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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33
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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.
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Affiliation(s)
- Ombretta Foresti
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
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34
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Delannoy M, Alves G, Vertommen D, Ma J, Boutry M, Navarre C. Identification of peptidases in Nicotiana tabacum leaf intercellular fluid. Proteomics 2008; 8:2285-98. [PMID: 18446799 DOI: 10.1002/pmic.200700507] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2007] [Indexed: 01/23/2023]
Abstract
Peptidases in the extracellular space might affect the integrity of recombinant proteins expressed in, and secreted from, plant cells. To identify extracellular peptidases, we recovered the leaf intercellular fluid from Nicotiana tabacum plants by an infiltration-centrifugation method. The activity of various peptidases was detected by an in vitro assay in the presence of specific inhibitors, using BSA and human serum gamma-globulin as substrates. Peptidases were detected by 1- and 2-D zymography in a polyacrylamide gel containing gelatin as substrate. Proteolytic activity was observed over a wide range of molecular masses equal to, or higher than, 45 kDa. To identify the peptidases, the extracellular proteins were digested with trypsin and analyzed by LC and MS. Seventeen peptides showing identity or similarity to predicted plant aspartic, cysteine, and serine peptidases have been identified. The extracellular localization of a cysteine peptidase aleurain homolog was also shown.
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Affiliation(s)
- Mélanie Delannoy
- Unité de Biochimie Physiologique, Institut des Sciences de la Vie, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
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35
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Jaillais Y, Fobis-Loisy I, Miège C, Gaude T. Evidence for a sorting endosome in Arabidopsis root cells. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 53:237-47. [PMID: 17999644 DOI: 10.1111/j.1365-313x.2007.03338.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
In eukaryotic cells, the endocytic and secretory pathways are key players in several physiological processes. These pathways are largely inter-connected in animal and yeast cells through organelles named sorting endosomes. Sorting endosomes are multi-vesicular compartments that redirect proteins towards various destinations, such as the lysosomes or vacuoles for degradation, the trans-Golgi network for retrograde transport and the plasma membrane for recycling. In contrast, cross-talk between the endocytic and secretory pathways has not been clearly established in plants, especially in terms of cargo protein trafficking. Here we show by co-localization analyses that endosomes labelled with the AtSORTING NEXIN1 (AtSNX1) protein overlap with the pre-vacuolar compartment in Arabidopsis root cells. In addition, alteration of the routing functions of AtSNX1 endosomes by drug treatments leads to mis-routing of endocytic and secretory cargo proteins. Based on these results, we propose that the AtSNX1 endosomal compartment represents a sorting endosome in root cells, and that this specialized organelle is conserved throughout eukaryotes.
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Affiliation(s)
- Yvon Jaillais
- Reproduction et Développement des Plantes, Institut Fédératif de Recherche 128, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université Claude Bernard Lyon I, Ecole Normale Supérieure de Lyon, France
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36
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Hinz G, Colanesi S, Hillmer S, Rogers JC, Robinson DG. Localization of vacuolar transport receptors and cargo proteins in the Golgi apparatus of developing Arabidopsis embryos. Traffic 2007; 8:1452-64. [PMID: 17696967 DOI: 10.1111/j.1600-0854.2007.00625.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Using immunogold electron microscopy, we have investigated the relative distribution of two types of vacuolar sorting receptors (VSR) and two different types of lumenal cargo proteins, which are potential ligands for these receptors in the secretory pathway of developing Arabidopsis embryos. Interestingly, both cargo proteins are deposited in the protein storage vacuole, which is the only vacuole present during the bent-cotyledon stage of embryo development. Cruciferin and aleurain do not share the same pattern of distribution in the Golgi apparatus. Cruciferin is mainly detected in the cis and medial cisternae, especially at the rims where storage proteins aggregate into dense vesicles (DVs). Aleurain is found throughout the Golgi stack, particularly in the trans cisternae and trans Golgi network where clathrin-coated vesicles (CCVs) are formed. Nevertheless, aleurain was detected in both DV and CCV. VSR-At1, a VSR that recognizes N-terminal vacuolar sorting determinants (VSDs) of the NPIR type, localizes mainly to the trans Golgi and is hardly detectable in DV. Receptor homology-transmembrane-RING H2 domain (RMR), a VSR that recognizes C-terminal VSDs, has a distribution that is very similar to that of cruciferin and is found in DV. Our results do not support a role for VSR-At1 in storage protein sorting, instead RMR proteins because of their distribution similar to that of cruciferin in the Golgi apparatus and their presence in DV are more likely candidates. Aleurain, which has an NPIR motif and seems to be primarily sorted via VSR-At1 into CCV, also possesses putative hydrophobic sorting determinants at its C-terminus that could allow the additional incorporation of this protein into DV.
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Affiliation(s)
- Giselbert Hinz
- Department of Cell Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, 69120 Heidelberg, Germany
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37
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Paul MJ, Frigerio L. Coated vesicles in plant cells. Semin Cell Dev Biol 2007; 18:471-8. [PMID: 17693105 DOI: 10.1016/j.semcdb.2007.07.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2007] [Revised: 07/04/2007] [Accepted: 07/04/2007] [Indexed: 10/23/2022]
Abstract
Coated vesicles represent vital transport intermediates in all eukaryotic cells. While the basic mechanisms of membrane exchange are conserved through the kingdoms, the unique topology of the plant endomembrane system is mirrored by several differences in the genesis, function and regulation of coated vesicles. Efforts to unravel the complex network of proteins underlying the behaviour of these vesicles have recently benefited from the application in planta of several molecular tools used in mammalian systems, as well as from advances in imaging technology and the ongoing analysis of the Arabidopsis genome. In this review, we provide an overview of the roles of coated vesicles in plant cells and highlight salient new developments in the field.
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Affiliation(s)
- Matthew J Paul
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom
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38
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Tapernoux-Lüthi EM, Schneider T, Keller F. The C-terminal sequence from common bugle leaf galactan:galactan galactosyltransferase is a non-sequence-specific vacuolar sorting determinant. FEBS Lett 2007; 581:1811-8. [PMID: 17434166 DOI: 10.1016/j.febslet.2007.03.068] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2007] [Revised: 03/23/2007] [Accepted: 03/23/2007] [Indexed: 11/17/2022]
Abstract
The Ajuga reptans L. galactan:galactan galactosyltransferase (ArGGT) is a vacuolar enzyme that synthesizes long-chain raffinose family oligosaccharides (RFOs), the major storage carbohydrates of this plant. ArGGT is structurally and functionally related to acid plant alpha-galactosidases (alpha-Gals) of the glycosylhydrolase family 27, present in the apoplast or the vacuole. Sequence comparison of acid alpha-Gals with ArGGT revealed that they all contain an N-terminal signal sequence and a highly similar core sequence. Additionally, ArGGT and some acid alpha-Gals contain C-terminal extensions with low sequence similarities to each other. Here, we show that the C-terminal pentapeptide, SLQMS, is a non-sequence-specific vacuolar sorting determinant. Analogously, we demonstrate that the C-terminal extensions of selected acid alpha-Gals from Arabidopsis, barley, and rice, are also non-sequence-specific vacuolar sorting determinants, suggesting the presence of at least one vacuolar form of acid alpha-Gal in every plant species.
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Affiliation(s)
- Esther M Tapernoux-Lüthi
- Institute of Plant Biology, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland
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39
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Wang J, Li Y, Lo SW, Hillmer S, Sun SSM, Robinson DG, Jiang L. Protein mobilization in germinating mung bean seeds involves vacuolar sorting receptors and multivesicular bodies. PLANT PHYSIOLOGY 2007; 143:1628-39. [PMID: 17322331 PMCID: PMC1851832 DOI: 10.1104/pp.107.096263] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Plants accumulate and store proteins in protein storage vacuoles (PSVs) during seed development and maturation. Upon seed germination, these storage proteins are mobilized to provide nutrients for seedling growth. However, little is known about the molecular mechanisms of protein degradation during seed germination. Here we test the hypothesis that vacuolar sorting receptor (VSR) proteins play a role in mediating protein degradation in germinating seeds. We demonstrate that both VSR proteins and hydrolytic enzymes are synthesized de novo during mung bean (Vigna radiata) seed germination. Immunogold electron microscopy with VSR antibodies demonstrate that VSRs mainly locate to the peripheral membrane of multivesicular bodies (MVBs), presumably as recycling receptors in day 1 germinating seeds, but become internalized to the MVB lumen, presumably for degradation at day 3 germination. Chemical cross-linking and immunoprecipitation with VSR antibodies have identified the cysteine protease aleurain as a specific VSR-interacting protein in germinating seeds. Further confocal immunofluorescence and immunogold electron microscopy studies demonstrate that VSR and aleurain colocalize to MVBs as well as PSVs in germinating seeds. Thus, MVBs in germinating seeds exercise dual functions: as a storage compartment for proteases that are physically separated from PSVs in the mature seed and as an intermediate compartment for VSR-mediated delivery of proteases from the Golgi apparatus to the PSV for protein degradation during seed germination.
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Affiliation(s)
- Junqi Wang
- Department of Biology and Molecular Biotechnology Program , Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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40
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Liénard D, Sourrouille C, Gomord V, Faye L. Pharming and transgenic plants. BIOTECHNOLOGY ANNUAL REVIEW 2007; 13:115-47. [PMID: 17875476 DOI: 10.1016/s1387-2656(07)13006-4] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Plant represented the essence of pharmacopoeia until the beginning of the 19th century when plant-derived pharmaceuticals were partly supplanted by drugs produced by the industrial methods of chemical synthesis. In the last decades, genetic engineering has offered an alternative to chemical synthesis, using bacteria, yeasts and animal cells as factories for the production of therapeutic proteins. More recently, molecular farming has rapidly pushed towards plants among the major players in recombinant protein production systems. Indeed, therapeutic protein production is safe and extremely cost-effective in plants. Unlike microbial fermentation, plants are capable of carrying out post-translational modifications and, unlike production systems based on mammalian cell cultures, plants are devoid of human infective viruses and prions. Furthermore, a large panel of strategies and new plant expression systems are currently developed to improve the plant-made pharmaceutical's yields and quality. Recent advances in the control of post-translational maturations in transgenic plants will allow them, in the near future, to perform human-like maturations on recombinant proteins and, hence, make plant expression systems suitable alternatives to animal cell factories.
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Affiliation(s)
- David Liénard
- Université de Rouen, CNRS UMR 6037, IFRMP 23, GDR 2590, Faculté des Sciences, Bât. Ext. Biologie, 76821 Mont-Saint-Aignan cedex, France
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41
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Becker B. Function and evolution of the vacuolar compartment in green algae and land plants (Viridiplantae). INTERNATIONAL REVIEW OF CYTOLOGY 2007; 264:1-24. [PMID: 17964920 DOI: 10.1016/s0074-7696(07)64001-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Plant vacuoles perform several different functions and are essential for the plant cell. The large central vacuoles of mature plant cells provide structural support, and they serve other functions, such as protein degradation and turnover, waste disposal, storage of metabolites, and cell growth. A unique feature of the plant vacuolar system is the presence of different types of vacuoles within the same cell. The current knowledge about the vacuolar compartments in plants and green algae is summarized and a hypothesis is presented to explain the origin of multiple types of vacuoles in plants.
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Affiliation(s)
- Burkhard Becker
- Botanical Institute, University of Cologne, 50931 Köln, Germany
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42
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Miao Y, Yan PK, Kim H, Hwang I, Jiang L. Localization of green fluorescent protein fusions with the seven Arabidopsis vacuolar sorting receptors to prevacuolar compartments in tobacco BY-2 cells. PLANT PHYSIOLOGY 2006; 142:945-62. [PMID: 16980567 PMCID: PMC1630755 DOI: 10.1104/pp.106.083618] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2006] [Accepted: 09/08/2006] [Indexed: 05/11/2023]
Abstract
We have previously demonstrated that vacuolar sorting receptor (VSR) proteins are concentrated on prevacuolar compartments (PVCs) in plant cells. PVCs in tobacco (Nicotiana tabacum) BY-2 cells are multivesicular bodies (MVBs) as defined by VSR proteins and the BP-80 reporter, where the transmembrane domain (TMD) and cytoplasmic tail (CT) sequences of BP-80 are sufficient and specific for correct targeting of the reporter to PVCs. The genome of Arabidopsis (Arabidopsis thaliana) contains seven VSR proteins, but little is known about their individual subcellular localization and function. Here, we study the subcellular localization of the seven Arabidopsis VSR proteins (AtVSR1-7) based on the previously proven hypothesis that the TMD and CT sequences correctly target individual VSR to its final destination in transgenic tobacco BY-2 cells. Toward this goal, we have generated seven chimeric constructs containing signal peptide (sp) linked to green fluorescent protein (GFP) and TMD/CT sequences (sp-GFP-TMD/CT) of the seven individual AtVSR. Transgenic tobacco BY-2 cell lines expressing these seven sp-GFP-TMD-CT fusions all exhibited typical punctate signals colocalizing with VSR proteins by confocal immunofluorescence. In addition, wortmannin caused the GFP-marked prevacuolar organelles to form small vacuoles, and VSR antibodies labeled these enlarged MVBs in transgenic BY-2 cells. Wortmannin also caused VSR-marked PVCs to vacuolate in other cell types, including Arabidopsis, rice (Oryza sativa), pea (Pisum sativum), and mung bean (Vigna radiata). Therefore, the seven AtVSRs are localized to MVBs in tobacco BY-2 cells, and wortmannin-induced vacuolation of PVCs is a general response in plants.
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Affiliation(s)
- Yansong Miao
- Department of Biology and Molecular Biotechnology Program, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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43
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Otegui MS, Herder R, Schulze J, Jung R, Staehelin LA. The proteolytic processing of seed storage proteins in Arabidopsis embryo cells starts in the multivesicular bodies. THE PLANT CELL 2006; 18:2567-81. [PMID: 17012602 PMCID: PMC1626608 DOI: 10.1105/tpc.106.040931] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We have investigated the transport of storage proteins, their processing proteases, and the Vacuolar Sorting Receptor-1/Epidermal Growth Factor Receptor-Like Protein1 (VSR-1/ATELP1) receptor during the formation of protein storage vacuoles in Arabidopsis thaliana embryos by means of high-pressure freezing/freeze substitution, electron tomography, immunolabeling techniques, and subcellular fractionation. The storage proteins and their processing proteases are segregated from each other within the Golgi cisternae and packaged into separate vesicles. The storage protein-containing vesicles but not the processing enzyme-containing vesicles carry the VSR-1/ATELP1 receptor. Both types of secretory vesicles appear to fuse into a type of prevacuolar multivesicular body (MVB). We have also determined that the proteolytic processing of the 2S albumins starts in the MVBs. We hypothesize that the compartmentalized processing of storage proteins in the MVBs may allow for the sequential activation of processing proteases as the MVB lumen gradually acidifies.
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Affiliation(s)
- Marisa S Otegui
- Department of Botany, University of Wisconsin, Madison, Wisconsin 53706, USA.
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44
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Foresti O, daSilva LLP, Denecke J. Overexpression of the Arabidopsis syntaxin PEP12/SYP21 inhibits transport from the prevacuolar compartment to the lytic vacuole in vivo. THE PLANT CELL 2006; 18:2275-93. [PMID: 16935987 PMCID: PMC1560924 DOI: 10.1105/tpc.105.040279] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Golgi-mediated transport to the lytic vacuole involves passage through the prevacuolar compartment (PVC), but little is known about how vacuolar proteins exit the PVC. We show that this last step is inhibited by overexpression of Arabidopsis thaliana syntaxin PEP12/SYP21, causing an accumulation of soluble and membrane cargo and the plant vacuolar sorting receptor BP80 in the PVC. Anterograde transport proceeds normally from the endoplasmic reticulum to the Golgi and the PVC, although export from the PVC appears to be compromised, affecting both anterograde membrane flow to the vacuole and the recycling route of BP80 to the Golgi. However, Golgi-mediated transport of soluble and membrane cargo toward the plasma membrane is not affected, but a soluble BP80 ligand is partially mis-sorted to the culture medium. We also observe clustering of individual PVC bodies that move together and possibly fuse with each other, forming enlarged compartments. We conclude that PEP12/SYP21 overexpression specifically inhibits export from the PVC without affecting the Golgi complex or compromising the secretory branch of the endomembrane system. The results provide a functional in vivo assay that confirms PEP12/SYP21 involvement in vacuolar sorting and indicates that excess of this syntaxin in the PVC can be detrimental for further transport from this organelle.
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Affiliation(s)
- Ombretta Foresti
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
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45
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Song J, Lee MH, Lee GJ, Yoo CM, Hwang I. Arabidopsis EPSIN1 plays an important role in vacuolar trafficking of soluble cargo proteins in plant cells via interactions with clathrin, AP-1, VTI11, and VSR1. THE PLANT CELL 2006; 18:2258-74. [PMID: 16905657 PMCID: PMC1560928 DOI: 10.1105/tpc.105.039123] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Epsin and related proteins play important roles in various steps of protein trafficking in animal and yeast cells. Many epsin homologs have been identified in plant cells from analysis of genome sequences. However, their roles have not been elucidated. Here, we investigate the expression, localization, and biological role in protein trafficking of an epsin homolog, Arabidopsis thaliana EPSIN1, which is expressed in most tissues we examined. In the cell, one pool of EPSIN1 is associated with actin filaments, producing a network pattern, and a second pool localizes primarily to the Golgi complex with a minor portion to the prevacuolar compartment, producing a punctate staining pattern. Protein pull-down and coimmunoprecipitation experiments reveal that Arabidopsis EPSIN1 interacts with clathrin, VTI11, gamma-adaptin-related protein (gamma-ADR), and vacuolar sorting receptor1 (VSR1). In addition, EPSIN1 colocalizes with clathrin and VTI11. The epsin1 mutant, which has a T-DNA insertion in EPSIN1, displays a defect in the vacuolar trafficking of sporamin:green fluorescent protein (GFP), but not in the secretion of invertase:GFP into the medium. Stably expressed HA:EPSIN1 complements this trafficking defect. Based on these data, we propose that EPSIN1 plays an important role in the vacuolar trafficking of soluble proteins at the trans-Golgi network via its interaction with gamma-ADR, VTI11, VSR1, and clathrin.
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Affiliation(s)
- Jinhee Song
- Division of Molecular and Life Sciences and Center for Plant Intracellular Trafficking, Pohang University of Science and Technology, Pohang 790-784, Korea
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46
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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.
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Affiliation(s)
- Peter Oliviusson
- Department of Cell Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, 69120 Heidelberg, Germany
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47
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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.
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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
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48
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Abstract
Plant vacuoles have multiple functions: they can act both as digestive organelles and as receptacles for storage proteins. Different types of vacuoles can coexist in the same cell, which adds complexity to the process of targeting to these compartments. A fuller understanding of this process is of evident value when endeavouring to exploit the plant secretory pathway for heterologous protein production. Positive sorting signals are required in order to sort proteins to vacuoles, and these have been split into three groups: ctVSS [C-terminal VSS (vacuolar sorting signals)], ssVSS (sequence-specific VSS) and physical structure VSS. The current working model posits that soluble proteins are delivered from the Golgi apparatus to the lytic vacuoles in clathrin-coated vesicles by virtue of their ssVSS, or to the storage vacuole [PSV (protein-storage vacuole)] in dense vesicles in a manner dependent on ctVSS or physical structure VSS. Although targeting to LV appears to be receptor-mediated, no such receptor has been identified for the recruitment of proteins to the PSV. We have studied the vacuolar targeting of two castor bean (Ricinus communis L.) storage proteins, proricin and pro 2 S albumin, in their native endosperm and in the heterologous system of tobacco protoplasts. We have found that both these proteins contain bona fide ssVSS and bind to sorting receptors in vitro in a similarly sequence-specific manner. The apparent similarities to lytic VSS and possible implications with respect to the working model for transport to storage vacuoles are discussed.
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49
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Park M, Lee D, Lee GJ, Hwang I. AtRMR1 functions as a cargo receptor for protein trafficking to the protein storage vacuole. ACTA ACUST UNITED AC 2005; 170:757-67. [PMID: 16115960 PMCID: PMC2171354 DOI: 10.1083/jcb.200504112] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Organellar proteins are sorted by cargo receptors on the way to their final destination. However, receptors for proteins that are destined for the protein storage vacuole (PSV) are largely unknown. In this study, we investigated the biological role that Arabidopsis thaliana receptor homology region transmembrane domain ring H2 motif protein (AtRMR) 1 plays in protein trafficking to the PSV. AtRMR1 mainly colocalized to the prevacuolar compartment of the PSV, but a minor portion also localized to the Golgi complex. The coexpression of AtRMR1 mutants that were localized to the Golgi complex strongly inhibited the trafficking of phaseolin to the PSV and caused accumulation of phaseolin in the Golgi complex or its secretion. Coimmunoprecipitation and in vitro binding assays revealed that the lumenal domain of AtRMR1 interacts with the COOH-terminal sorting signal of phaseolin at acidic pH. Furthermore, phaseolin colocalized with AtRMR1 on its way to the PSV. Based on these results, we propose that AtRMR1 functions as the sorting receptor of phaseolin for its trafficking to the PSV.
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Affiliation(s)
- Misoon Park
- Division of Molecular and Life Sciences, Center for Plant Intracellular Trafficking, Pohang University of Science and Technology, Pohang 790-784, Korea
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50
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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.
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Affiliation(s)
- David G Robinson
- Heidelberg Institute for Plant Sciences, Cell Biology, University of Heidelberg, Im Neuenheimer Feld 230, D-69120 Heidelberg, Germany
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