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Gendre D, McFarlane HE, Johnson E, Mouille G, Sjödin A, Oh J, Levesque-Tremblay G, Watanabe Y, Samuels L, Bhalerao RP. Trans-Golgi network localized ECHIDNA/Ypt interacting protein complex is required for the secretion of cell wall polysaccharides in Arabidopsis. THE PLANT CELL 2013; 25:2633-46. [PMID: 23832588 PMCID: PMC3753388 DOI: 10.1105/tpc.113.112482] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The secretion of cell wall polysaccharides through the trans-Golgi network (TGN) is required for plant cell elongation. However, the components mediating the post-Golgi secretion of pectin and hemicellulose, the two major cell wall polysaccharides, are largely unknown. We identified evolutionarily conserved YPT/RAB GTPase Interacting Protein 4a (YIP4a) and YIP4b (formerly YIP2), which form a TGN-localized complex with ECHIDNA (ECH) in Arabidopsis thaliana. The localization of YIP4 and ECH proteins at the TGN is interdependent and influences the localization of VHA-a1 and SYP61, which are key components of the TGN. YIP4a and YIP4b act redundantly, and the yip4a yip4b double mutants have a cell elongation defect. Genetic, biochemical, and cell biological analyses demonstrate that the ECH/YIP4 complex plays a key role in TGN-mediated secretion of pectin and hemicellulose to the cell wall in dark-grown hypocotyls and in secretory cells of the seed coat. In keeping with these observations, Fourier transform infrared microspectroscopy analysis revealed that the ech and yip4a yip4b mutants exhibit changes in their cell wall composition. Overall, our results reveal a TGN subdomain defined by ECH/YIP4 that is required for the secretion of pectin and hemicellulose and distinguishes the role of the TGN in secretion from its roles in endocytic and vacuolar trafficking.
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Affiliation(s)
- Delphine Gendre
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, S-901 83 Umea, Sweden
| | - Heather E. McFarlane
- Department of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Errin Johnson
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, S-901 83 Umea, Sweden
| | - Gregory Mouille
- Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318, Institut National de la Recherche Agronomique–AgroParisTech, Institut National de la Recherche Agronomique Centre de Versailles-Grignon, 78026 Versailles cedex, France
| | - Andreas Sjödin
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, S-901 83 Umea, Sweden
| | - Jaesung Oh
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, S-901 83 Umea, Sweden
| | | | - Yoichiro Watanabe
- Department of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Lacey Samuels
- Department of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Rishikesh P. Bhalerao
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, S-901 83 Umea, Sweden
- Address correspondence to
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Virgili-López G, Langhans M, Bubeck J, Pedrazzini E, Gouzerh G, Neuhaus JM, Robinson DG, Vitale A. Comparison of membrane targeting strategies for the accumulation of the human immunodeficiency virus p24 protein in transgenic tobacco. Int J Mol Sci 2013; 14:13241-65. [PMID: 23803657 PMCID: PMC3742185 DOI: 10.3390/ijms140713241] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Revised: 05/28/2013] [Accepted: 06/17/2013] [Indexed: 01/09/2023] Open
Abstract
Membrane anchorage was tested as a strategy to accumulate recombinant proteins in transgenic plants. Transmembrane domains of different lengths and topology were fused to the cytosolic HIV antigen p24, to promote endoplasmic reticulum (ER) residence or traffic to distal compartments of the secretory pathway in transgenic tobacco. Fusions to a domain of the maize seed storage protein γ-zein were also expressed, as a reference strategy that leads to very high stability via the formation of large polymers in the ER lumen. Although all the membrane anchored constructs were less stable compared to the zein fusions, residence at the ER membrane either as a type I fusion (where the p24 sequence is luminal) or a tail-anchored fusion (where the p24 sequence is cytosolic) resulted in much higher stability than delivery to the plasma membrane or intermediate traffic compartments. Delivery to the tonoplast was never observed. The inclusion of a thrombin cleavage site allowed for the quantitative in vitro recovery of p24 from all constructs. These results point to the ER as suitable compartment for the accumulation of membrane-anchored recombinant proteins in plants.
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Affiliation(s)
- Goretti Virgili-López
- Department of Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg D-69120, Germany; E-Mails: (G.V.-L.); (M.L.); (J.B.)
- Institute of Agricultural Biology and Biotechnology, National Research Council (CNR), via Bassini 15, Milano 20133, Italy; E-Mail:
- Laboratory of Cell and Molecular Biology, University of Neuchatel, Rue Emile-Argand 11, Neuchâtel CH-2000, Switzerland; E-Mail:
| | - Markus Langhans
- Department of Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg D-69120, Germany; E-Mails: (G.V.-L.); (M.L.); (J.B.)
| | - Julia Bubeck
- Department of Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg D-69120, Germany; E-Mails: (G.V.-L.); (M.L.); (J.B.)
| | - Emanuela Pedrazzini
- Institute of Agricultural Biology and Biotechnology, National Research Council (CNR), via Bassini 15, Milano 20133, Italy; E-Mail:
| | - Guillaume Gouzerh
- Laboratory of Cell and Molecular Biology, University of Neuchatel, Rue Emile-Argand 11, Neuchâtel CH-2000, Switzerland; E-Mail:
| | - Jean-Marc Neuhaus
- Laboratory of Cell and Molecular Biology, University of Neuchatel, Rue Emile-Argand 11, Neuchâtel CH-2000, Switzerland; E-Mail:
| | - David G. Robinson
- Department of Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg D-69120, Germany; E-Mails: (G.V.-L.); (M.L.); (J.B.)
| | - Alessandro Vitale
- Institute of Agricultural Biology and Biotechnology, National Research Council (CNR), via Bassini 15, Milano 20133, Italy; E-Mail:
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53
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Onelli E, Moscatelli A. Endocytic Pathways and Recycling in Growing Pollen Tubes. PLANTS (BASEL, SWITZERLAND) 2013; 2:211-29. [PMID: 27137373 PMCID: PMC4844360 DOI: 10.3390/plants2020211] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Revised: 03/21/2013] [Accepted: 03/26/2013] [Indexed: 12/31/2022]
Abstract
Pollen tube growth is based on transport of secretory vesicles into the apical region where they fuse with a small area of the plasma membrane. The amount of secretion greatly exceeds the quantity of membrane required for growth. Mechanisms of membrane retrieval have recently been demonstrated and partially characterized using FM (Fei Mao) dyes or charged nanogold. Both these probes reveal that clathrin-dependent and -independent endocytosis occur in pollen tubes and are involved in distinct degradation pathways and membrane recycling. Exocytosis, internalization and sorting of PM proteins/lipids depend on the integrity of the actin cytoskeleton and are involved in actin filament organization. However, some kinds of endocytic and exocytic processes occurring in the central area of the tip still need to be characterized. Analysis of secretion dynamics and data derived from endocytosis highlight the complexity of events occurring in the tip region and suggest a new model of pollen tube growth.
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Affiliation(s)
- Elisabetta Onelli
- Dipartimento di Bioscienze, Universita' degli Studi di Milano Via Celoria 26, 20133 Milano, Italy.
| | - Alessandra Moscatelli
- Dipartimento di Bioscienze, Universita' degli Studi di Milano Via Celoria 26, 20133 Milano, Italy.
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Breckels LM, Gatto L, Christoforou A, Groen AJ, Lilley KS, Trotter MWB. The effect of organelle discovery upon sub-cellular protein localisation. J Proteomics 2013; 88:129-40. [PMID: 23523639 DOI: 10.1016/j.jprot.2013.02.019] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 02/16/2013] [Accepted: 02/21/2013] [Indexed: 12/31/2022]
Abstract
UNLABELLED Prediction of protein sub-cellular localisation by employing quantitative mass spectrometry experiments is an expanding field. Several methods have led to the assignment of proteins to specific subcellular localisations by partial separation of organelles across a fractionation scheme coupled with computational analysis. Methods developed to analyse organelle data have largely employed supervised machine learning algorithms to map unannotated abundance profiles to known protein-organelle associations. Such approaches are likely to make association errors if organelle-related groupings present in experimental output are not included in data used to create a protein-organelle classifier. Currently, there is no automated way to detect organelle-specific clusters within such datasets. In order to address the above issues we adapted a phenotype discovery algorithm, originally created to filter image-based output for RNAi screens, to identify putative subcellular groupings in organelle proteomics experiments. We were able to mine datasets to a deeper level and extract interesting phenotype clusters for more comprehensive evaluation in an unbiased fashion upon application of this approach. Organelle-related protein clusters were identified beyond those sufficiently annotated for use as training data. Furthermore, we propose avenues for the incorporation of observations made into general practice for the classification of protein-organelle membership from quantitative MS experiments. BIOLOGICAL SIGNIFICANCE Protein sub-cellular localisation plays an important role in molecular interactions, signalling and transport mechanisms. The prediction of protein localisation by quantitative mass-spectrometry (MS) proteomics is a growing field and an important endeavour in improving protein annotation. Several such approaches use gradient-based separation of cellular organelle content to measure relative protein abundance across distinct gradient fractions. The distribution profiles are commonly mapped in silico to known protein-organelle associations via supervised machine learning algorithms, to create classifiers that associate unannotated proteins to specific organelles. These strategies are prone to error, however, if organelle-related groupings present in experimental output are not represented, for example owing to the lack of existing annotation, when creating the protein-organelle mapping. Here, the application of a phenotype discovery approach to LOPIT gradient-based MS data identifies candidate organelle phenotypes for further evaluation in an unbiased fashion. Software implementation and usage guidelines are provided for application to wider protein-organelle association experiments. In the wider context, semi-supervised organelle discovery is discussed as a paradigm with which to generate new protein annotations from MS-based organelle proteomics experiments.
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Affiliation(s)
- L M Breckels
- Cambridge Centre for Proteomics, Department of Biochemistry, University of Cambridge, CB2 1QR, UK
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55
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Barbez E, Laňková M, Pařezová M, Maizel A, Zažímalová E, Petrášek J, Friml J, Kleine-Vehn J. Single-cell-based system to monitor carrier driven cellular auxin homeostasis. BMC PLANT BIOLOGY 2013; 13:20. [PMID: 23379388 PMCID: PMC3598821 DOI: 10.1186/1471-2229-13-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 01/31/2013] [Indexed: 05/06/2023]
Abstract
BACKGROUND Abundance and distribution of the plant hormone auxin play important roles in plant development. Besides other metabolic processes, various auxin carriers control the cellular level of active auxin and, hence, are major regulators of cellular auxin homeostasis. Despite the developmental importance of auxin transporters, a simple medium-to-high throughput approach to assess carrier activities is still missing. Here we show that carrier driven depletion of cellular auxin correlates with reduced nuclear auxin signaling in tobacco Bright Yellow-2 (BY-2) cell cultures. RESULTS We developed an easy to use transient single-cell-based system to detect carrier activity. We use the relative changes in signaling output of the auxin responsive promoter element DR5 to indirectly visualize auxin carrier activity. The feasibility of the transient approach was demonstrated by pharmacological and genetic interference with auxin signaling and transport. As a proof of concept, we provide visual evidence that the prominent auxin transport proteins PIN-FORMED (PIN)2 and PIN5 regulate cellular auxin homeostasis at the plasma membrane and endoplasmic reticulum (ER), respectively. Our data suggest that PIN2 and PIN5 have different sensitivities to the auxin transport inhibitor 1-naphthylphthalamic acid (NPA). Also the putative PIN-LIKES (PILS) auxin carrier activity at the ER is insensitive to NPA in our system, indicating that NPA blocks intercellular, but not intracellular auxin transport. CONCLUSIONS This single-cell-based system is a useful tool by which the activity of putative auxin carriers, such as PINs, PILS and WALLS ARE THIN1 (WAT1), can be indirectly visualized in a medium-to-high throughput manner. Moreover, our single cell system might be useful to investigate also other hormonal signaling pathways, such as cytokinin.
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Affiliation(s)
- Elke Barbez
- Department of Plant Systems Biology, VIB and Department of Plant Biotechnology and Genetics, Ghent University, 9052, Gent, Belgium
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna (BOKU), 1190, Vienna, Austria
| | - Martina Laňková
- Institute of Experimental Botany, The Academy of Sciences of the Czech Republic, 16502, Praha 6, Czech Republic
| | - Markéta Pařezová
- Institute of Experimental Botany, The Academy of Sciences of the Czech Republic, 16502, Praha 6, Czech Republic
| | - Alexis Maizel
- Department of Stem Cell Biology, Center for Organismal Studies, University of Heidelberg, 69120, Heidelberg, Germany
| | - Eva Zažímalová
- Institute of Experimental Botany, The Academy of Sciences of the Czech Republic, 16502, Praha 6, Czech Republic
| | - Jan Petrášek
- Institute of Experimental Botany, The Academy of Sciences of the Czech Republic, 16502, Praha 6, Czech Republic
| | - Jiří Friml
- Department of Plant Systems Biology, VIB and Department of Plant Biotechnology and Genetics, Ghent University, 9052, Gent, Belgium
- Department of Functional Genomics and Proteomics, Faculty of Science, and CEITEC, Masaryk University, Kamenice 5, CZ-62500, Brno, Czech Republic
| | - Jürgen Kleine-Vehn
- Department of Plant Systems Biology, VIB and Department of Plant Biotechnology and Genetics, Ghent University, 9052, Gent, Belgium
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna (BOKU), 1190, Vienna, Austria
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Stierhof YD, Viotti C, Scheuring D, Sturm S, Robinson DG. Sorting nexins 1 and 2a locate mainly to the TGN. PROTOPLASMA 2013; 250:235-40. [PMID: 22447127 DOI: 10.1007/s00709-012-0399-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 03/14/2012] [Indexed: 05/26/2023]
Abstract
The subcellular localization of the sorting nexins (SNXs) in higher plants is a matter of controversy. Previous confocal laser scanning microscopy (CLSM studies on root cells from a transgenic Arabidopsis line expressing SNX1-GFP have suggested that this SNX is present on an endosome having characteristics of both the trans-Golgi network (TGN) and the multivesicular body (MVB). In contrast, SNX2a locates exclusively to the TGN when transiently expressed in tobacco mesophyll protoplasts. By performing immunogold electron microscopy on cryofixed Arabidopsis roots, we have tried to clarify the situation. Both SNX1-GFP and endogenous SNX2a locate principally to the TGN. Labeling of MVBs could not be confirmed with any certainty.
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Affiliation(s)
- York-Dieter Stierhof
- Microscopy, Centre for Plant Molecular Biology, University of Tübingen, 72076 Tübingen, Germany
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57
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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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58
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Ding Y, Wang J, Wang J, Stierhof YD, Robinson DG, Jiang L. Unconventional protein secretion. TRENDS IN PLANT SCIENCE 2012; 17:606-15. [PMID: 22784825 DOI: 10.1016/j.tplants.2012.06.004] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2012] [Revised: 06/08/2012] [Accepted: 06/12/2012] [Indexed: 05/11/2023]
Abstract
It is generally believed that protein secretion or exocytosis is achieved via a conventional ER (endoplasmic reticulum)-Golgi-TGN (trans-Golgi network)-PM (plasma membrane) pathway in the plant endomembrane system. However, such signal peptide (SP)-dependent protein secretion cannot explain the increasing number of SP-lacking proteins which are found outside of the PM in plant cells. The process by which such leaderless secretory proteins (LSPs) gain access to the cell exterior is termed unconventional protein secretion (UPS) and has been well-studied in animal and yeast cells, but largely ignored by the plant community. Here, we review the evidence for UPS in plants especially in regard to the recently discovered EXPO (exocyst-positive-organelle).
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Affiliation(s)
- Yu Ding
- School of Life Sciences, Centre for Cell and Developmental Biology, the Chinese University of Hong Kong, Hong Kong, China
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59
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Scheuring D, Künzl F, Viotti C, Yan MSW, Jiang L, Schellmann S, Robinson DG, Pimpl P. Ubiquitin initiates sorting of Golgi and plasma membrane proteins into the vacuolar degradation pathway. BMC PLANT BIOLOGY 2012; 12:164. [PMID: 22970698 PMCID: PMC3534617 DOI: 10.1186/1471-2229-12-164] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 07/13/2012] [Indexed: 05/18/2023]
Abstract
BACKGROUND In yeast and mammals, many plasma membrane (PM) proteins destined for degradation are tagged with ubiquitin. These ubiquitinated proteins are internalized into clathrin-coated vesicles and are transported to early endosomal compartments. There, ubiquitinated proteins are sorted by the endosomal sorting complex required for transport (ESCRT) machinery into the intraluminal vesicles of multivesicular endosomes. Degradation of these proteins occurs after endosomes fuse with lysosomes/lytic vacuoles to release their content into the lumen. In plants, some PM proteins, which cycle between the PM and endosomal compartments, have been found to be ubiquitinated, but it is unclear whether ubiquitin is sufficient to mediate internalization and thus acts as a primary sorting signal for the endocytic pathway. To test whether plants use ubiquitin as a signal for the degradation of membrane proteins, we have translationally fused ubiquitin to different fluorescent reporters for the plasma membrane and analyzed their transport. RESULTS Ubiquitin-tagged PM reporters localized to endosomes and to the lumen of the lytic vacuole in tobacco mesophyll protoplasts and in tobacco epidermal cells. The internalization of these reporters was significantly reduced if clathrin-mediated endocytosis was inhibited by the coexpression of a mutant of the clathrin heavy chain, the clathrin hub. Surprisingly, a ubiquitin-tagged reporter for the Golgi was also transported into the lumen of the vacuole. Vacuolar delivery of the reporters was abolished upon inhibition of the ESCRT machinery, indicating that the vacuolar delivery of these reporters occurs via the endocytic transport route. CONCLUSIONS Ubiquitin acts as a sorting signal at different compartments in the endomembrane system to target membrane proteins into the vacuolar degradation pathway: If displayed at the PM, ubiquitin triggers internalization of PM reporters into the endocytic transport route, but it also mediates vacuolar delivery if displayed at the Golgi. In both cases, ubiquitin-tagged proteins travel via early endosomes and multivesicular bodies to the lytic vacuole. This suggests that vacuolar degradation of ubiquitinated proteins is not restricted to PM proteins but might also facilitate the turnover of membrane proteins in the early secretory pathway.
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Affiliation(s)
- David Scheuring
- Department of Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg, 69120, Germany
| | - Fabian Künzl
- Department of Developmental Genetics, Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, 72076, Germany
| | - Corrado Viotti
- Department of Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg, 69120, Germany
- Plant Developmental Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg, 69120, Germany
| | - Melody San Wan Yan
- School of Life Sciences, Centre for Cell and Developmental Biology, The Chinese University of Hong Kong, Shatin NT, Hong Kong, PR China
| | - Liwen Jiang
- School of Life Sciences, Centre for Cell and Developmental Biology, The Chinese University of Hong Kong, Shatin NT, Hong Kong, PR China
| | - Swen Schellmann
- Botanical Institute, Biozentrum Köln, University of Cologne, Cologne, 50674, Germany
| | - David G Robinson
- Department of Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg, 69120, Germany
| | - Peter Pimpl
- Department of Developmental Genetics, Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, 72076, Germany
- Department of Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg, 69120, Germany
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Robinson DG, Pimpl P, Scheuring D, Stierhof YD, Sturm S, Viotti C. Trying to make sense of retromer. TRENDS IN PLANT SCIENCE 2012; 17:431-9. [PMID: 22502774 DOI: 10.1016/j.tplants.2012.03.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 03/13/2012] [Accepted: 03/15/2012] [Indexed: 05/08/2023]
Abstract
Retromer is a cytosolic protein complex which binds to post-Golgi organelles involved in the trafficking of proteins to the lytic compartment of the cell. In non-plant organisms, retromer mediates the recycling of acid hydrolase receptors from early endosomal (EE) compartments. In plants, retromer components are required for the targeting of vacuolar storage proteins, and for the recycling of endocytosed PIN proteins. However, there are contradictory reports as to the localization of the sorting nexins and the core subunit of retromer. There is also uncertainty as to the identity of the organelles from which vacuolar sorting receptors (VSRs) and endocytosed plasma membrane (PM) proteins are recycled. In this review we try to resolve some of these conflicting observations.
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Affiliation(s)
- David G Robinson
- Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany.
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61
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Cai Y, Zhuang X, Wang J, Wang H, Lam SK, Gao C, Wang X, Jiang L. Vacuolar degradation of two integral plasma membrane proteins, AtLRR84A and OsSCAMP1, is cargo ubiquitination-independent and prevacuolar compartment-mediated in plant cells. Traffic 2012; 13:1023-40. [PMID: 22486829 DOI: 10.1111/j.1600-0854.2012.01360.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2012] [Revised: 04/02/2012] [Accepted: 04/04/2012] [Indexed: 12/31/2022]
Abstract
In plant cells, how integral plasma membrane (PM) proteins are degraded in a cargo ubiquitination-independent manner remains elusive. Here, we studied the degradative pathway of two plant PM proteins: AtLRR84A, a type I integral membrane protein belonging to the leucine-rich repeat receptor-like kinase protein family, and OsSCAMP1 (rice secretory carrier membrane protein 1), a tetraspan transmembrane protein located on the PM and trans-Golgi network (TGN) or early endosome (EE). Using wortmannin and ARA7(Q69L) mutant that could enlarge the multivesicular body (MVB) or prevacuolar compartment (PVC) as tools, we demonstrated that, when expressed as green fluorescent protein (GFP) fusions in tobacco BY-2 or Arabidopsis protoplasts, both AtLRR84A and OsSCAMP1 were degraded in the lytic vacuole via the internal vesicles of MVB/PVC in a cargo ubiquitination-independent manner. Such MVB/PVC-mediated vacuolar degradation of PM proteins was further supported by immunocytochemical electron microscopy (immunoEM) study showing the labeling of the fusions on the internal vesicles of the PVC/MVB. Thus, cargo ubiquitination-independent and PVC-mediated degradation of PM proteins in the vacuole is functionally operated in plant cells.
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Affiliation(s)
- Yi Cai
- School of Life Sciences, Centre for Cell and Developmental Biology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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62
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Herberth S, Shahriari M, Bruderek M, Hessner F, Müller B, Hülskamp M, Schellmann S. Artificial ubiquitylation is sufficient for sorting of a plasma membrane ATPase to the vacuolar lumen of Arabidopsis cells. PLANTA 2012; 236:63-77. [PMID: 22258747 DOI: 10.1007/s00425-012-1587-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Accepted: 12/30/2011] [Indexed: 05/21/2023]
Abstract
Sorting of transmembrane proteins into the inner vesicles of multivesicular bodies for subsequent delivery to the vacuole/lysosome can be induced by attachment of a single ubiquitin or K63-linked ubiquitin chains to the cytosolic portion of the cargo in yeast and mammals. In plants, large efforts have been undertaken to elucidate the mechanisms of vacuolar trafficking of soluble proteins. Sorting of transmembrane proteins, by contrast, is still largely unexplored. As a proof of principle, that ubiquitin is involved in vacuolar sorting in plants we show that a translational fusion of a single ubiquitin to the Arabidopsis plasma membrane ATPase PMA-EGFP is sufficient to induce its endocytosis and sorting into the vacuolar lumen. Sorting of the artificial reporter is not dependent on ubiquitin chain formation, but involves ubiquitin's hydrophobic patch and can be inhibited by coexpression of a dominant-negative version of the ESCRT (endosomal sorting complex required for transport) related protein AtSKD1 (SUPPRESSOR OF K+ TRANSPORT GROWTH DEFECT1). Our results suggest that ubiquitin can in principle act as vacuolar sorting signal in plants.
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Affiliation(s)
- Stefanie Herberth
- Botanical Institute III, Biocenter, University of Cologne, Zülpicher Str. 47b, 50674, Cologne, Germany
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63
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Cho M, Lee ZW, Cho HT. ATP-binding cassette B4, an auxin-efflux transporter, stably associates with the plasma membrane and shows distinctive intracellular trafficking from that of PIN-FORMED proteins. PLANT PHYSIOLOGY 2012; 159:642-54. [PMID: 22492845 PMCID: PMC3375931 DOI: 10.1104/pp.112.196139] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Intracellular trafficking of auxin transporters has been implicated in diverse developmental processes in plants. Although the dynamic trafficking pathways of PIN-FORMED auxin efflux proteins have been studied intensively, the trafficking of ATP-binding cassette protein subfamily B proteins (ABCBs; another group of auxin efflux carriers) still remains largely uncharacterized. In this study, we address the intracellular trafficking of ABCB4 in Arabidopsis (Arabidopsis thaliana) root epidermal cells. Pharmacological analysis showed that ABCB4 barely recycled between the plasma membrane and endosomes, although it slowly endocytosed via the lytic vacuolar pathway. Fluorescence recovery after photobleaching analysis revealed that ABCB4 is strongly retained in the plasma membrane, further supporting ABCB4's nonrecycling property. The endocytosis of ABCB4 was not dependent on the GNOM-LIKE1 function, and the sensitivity of ABCB4 to brefeldin A required guanine nucleotide exchange factors for adenosyl ribosylation factor other than GNOM. These characteristics of intracellular trafficking of ABCB4 are well contrasted with those of PIN-FORMED proteins, suggesting that ABCB4 may be a basic and constitutive auxin efflux transporter for cellular auxin homeostasis.
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64
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Takáč T, Pechan T, Samajová O, Ovečka M, Richter H, Eck C, Niehaus K, Samaj J. Wortmannin treatment induces changes in Arabidopsis root proteome and post-Golgi compartments. J Proteome Res 2012; 11:3127-42. [PMID: 22524784 DOI: 10.1021/pr201111n] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Wortmannin is a widely used pharmaceutical compound which is employed to define vesicular trafficking routes of particular proteins or cellular compounds. It targets phosphatidylinositol 3-kinase and phosphatidylinositol 4-kinases in a dose-dependent manner leading to the inhibition of protein vacuolar sorting and endocytosis. Combined proteomics and cell biological approaches have been used in this study to explore the effects of wortmannin on Arabidopsis root cells, especially on proteome and endomembrane trafficking. On the subcellular level, wortmannin caused clustering, fusion, and swelling of trans-Golgi network (TGN) vesicles and multivesicular bodies (MVBs) leading to the formation of wortmannin-induced multivesicular compartments. Appearance of wortmannin-induced compartments was associated with depletion of TGN as revealed by electron microscopy. On the proteome level, wortmannin induced massive changes in protein abundance profiles. Wortmannin-sensitive proteins belonged to various functional classes. An inhibition of vacuolar trafficking by wortmannin was related to the downregulation of proteins targeted to the vacuole, as showed for vacuolar proteases. A small GTPase, RabA1d, which regulates vesicular trafficking at TGN, was identified as a new protein negatively affected by wortmannin. In addition, Sec14 was upregulated and PLD1 alpha was downregulated by wortmannin.
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Affiliation(s)
- Tomáš Takáč
- Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University , Šlechtitelů 11, CZ-783 71 Olomouc, Czech Republic
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65
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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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66
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Posttranslational modification and trafficking of PIN auxin efflux carriers. Mech Dev 2012; 130:82-94. [PMID: 22425600 DOI: 10.1016/j.mod.2012.02.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2011] [Revised: 02/03/2012] [Accepted: 02/10/2012] [Indexed: 11/23/2022]
Abstract
Cell-to-cell communication is absolutely essential for multicellular organisms. Both animals and plants use chemicals called hormones for intercellular signaling. However, multicellularity of plants and animals has evolved independently, which led to establishment of distinct strategies in order to cope with variations in an ever-changing environment. The phytohormone auxin is crucial to plant development and patterning. PIN auxin efflux carrier-driven polar auxin transport regulates plant development as it controls asymmetric auxin distribution (auxin gradients), which in turn modulates a wide range of developmental processes. Internal and external cues trigger a number of posttranslational PIN auxin carrier modifications that were demonstrated to decisively influence variations in adaptive growth responses. In this review, we highlight recent advances in the analysis of posttranslational modification of PIN auxin efflux carriers, such as phosphorylation and ubiquitylation, and discuss their eminent role in directional vesicle trafficking, PIN protein de-/stabilization and auxin transport activity. We conclude with updated models, in which we attempt to integrate the mechanistic relevance of posttranslational modifications of PIN auxin carriers for the dynamic nature of plant development.
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67
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Hillmer S, Viotti C, Robinson DG. An improved procedure for low-temperature embedding of high-pressure frozen and freeze-substituted plant tissues resulting in excellent structural preservation and contrast. J Microsc 2012; 247:43-7. [PMID: 22360578 DOI: 10.1111/j.1365-2818.2011.03595.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Here we describe refinements in the processing of high-pressure frozen samples of delicate plant tissues for immuno-electron microscopy. These involve: shortened freeze-substitution schedules, lower temperatures during processing and polymerisation, the avoidance of temperature fluctuations and the optimisation of heat transfer from the specimens using small disposable aluminium containers. The application of these modifications leads to very good structural preservation and selective membrane contrast. As a result, the versatility of the method is increased since not only immuno-electron microscopical studies can be performed but often the quality is also quite suitable for structural investigations.
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Affiliation(s)
- S Hillmer
- Department of Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg, Germany.
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68
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Drakakaki G, van de Ven W, Pan S, Miao Y, Wang J, Keinath NF, Weatherly B, Jiang L, Schumacher K, Hicks G, Raikhel N. Isolation and proteomic analysis of the SYP61 compartment reveal its role in exocytic trafficking in Arabidopsis. Cell Res 2012; 22:413-24. [PMID: 21826108 PMCID: PMC3271593 DOI: 10.1038/cr.2011.129] [Citation(s) in RCA: 176] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2010] [Revised: 04/01/2011] [Accepted: 06/07/2011] [Indexed: 11/08/2022] Open
Abstract
The endomembrane system is a complex and dynamic intracellular trafficking network. It is very challenging to track individual vesicles and their cargos in real time; however, affinity purification allows vesicles to be isolated in their natural state so that their constituent proteins can be identified. Pioneering this approach in plants, we isolated the SYP61 trans-Golgi network compartment and carried out a comprehensive proteomic analysis of its contents with only minimal interference from other organelles. The proteome of SYP61 revealed the association of proteins of unknown function that have previously not been ascribed to this compartment. We identified a complete SYP61 SNARE complex, including regulatory proteins and validated the proteome data by showing that several of these proteins associated with SYP61 in planta. We further identified the SYP121-complex and cellulose synthases, suggesting that SYP61 plays a role in the exocytic trafficking and the transport of cell wall components to the plasma membrane. The presence of proteins of unknown function in the SYP61 proteome including ECHIDNA offers the opportunity to identify novel trafficking components and cargos. The affinity purification of plant vesicles in their natural state provides a basis for further analysis and dissection of complex endomembrane networks. The approach is widely applicable and can afford the study of several vesicle populations in plants, which can be compared with the SYP61 vesicle proteome.
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Affiliation(s)
- Georgia Drakakaki
- Department of Botany and Plant Sciences, Center for Plant Cell Biology, Institute for Integrative Genome Biology, 4119C Genomics Building, University of California Riverside, CA 92521, USA
- Current address: Department of Plant Sciences, University of California, Davis, CA 95616, USA
| | - Wilhelmina van de Ven
- Department of Botany and Plant Sciences, Center for Plant Cell Biology, Institute for Integrative Genome Biology, 4119C Genomics Building, University of California Riverside, CA 92521, USA
| | - Songqin Pan
- Department of Botany and Plant Sciences, Center for Plant Cell Biology, Institute for Integrative Genome Biology, 4119C Genomics Building, University of California Riverside, CA 92521, USA
| | - Yansong Miao
- School of Life Sciences, Center for Cell and Developmental Biology, Chinese University of Hong Kong, New Territories, Hong Kong, China
- Current address: Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Junqi Wang
- School of Life Sciences, Center for Cell and Developmental Biology, Chinese University of Hong Kong, New Territories, Hong Kong, China
| | - Nana F Keinath
- Heidelberg Institute for Plant Science, Im Neuenheimer Feld 230, Heidelberg 69120, Germany
| | - Brent Weatherly
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
- NuSep Inc., Bogart, GA 30622, USA
| | - Liwen Jiang
- School of Life Sciences, Center for Cell and Developmental Biology, Chinese University of Hong Kong, New Territories, Hong Kong, China
| | - Karin Schumacher
- Heidelberg Institute for Plant Science, Im Neuenheimer Feld 230, Heidelberg 69120, Germany
| | - Glenn Hicks
- Department of Botany and Plant Sciences, Center for Plant Cell Biology, Institute for Integrative Genome Biology, 4119C Genomics Building, University of California Riverside, CA 92521, USA
| | - Natasha Raikhel
- Department of Botany and Plant Sciences, Center for Plant Cell Biology, Institute for Integrative Genome Biology, 4119C Genomics Building, University of California Riverside, CA 92521, USA
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69
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Contento AL, Bassham DC. Structure and function of endosomes in plant cells. J Cell Sci 2012; 125:3511-8. [DOI: 10.1242/jcs.093559] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Endosomes are a heterogeneous collection of organelles that function in the sorting and delivery of internalized material from the cell surface and the transport of materials from the Golgi to the lysosome or vacuole. Plant endosomes have some unique features, with an organization distinct from that of yeast or animal cells. Two clearly defined endosomal compartments have been studied in plant cells, the trans-Golgi network (equivalent to the early endosome) and the multivesicular body (equivalent to the late endosome), with additional endosome types (recycling endosome, late prevacuolar compartment) also a possibility. A model has been proposed in which the trans-Golgi network matures into a multivesicular body, which then fuses with the vacuole to release its cargo. In addition to basic trafficking functions, endosomes in plant cells are known to function in maintenance of cell polarity by polar localization of hormone transporters and in signaling pathways after internalization of ligand-bound receptors. These signaling functions are exemplified by the BRI1 brassinosteroid hormone receptor and by receptors for pathogen elicitors that activate defense responses. After endocytosis of these receptors from the plasma membrane, endosomes act as a signaling platform, thus playing an essential role in plant growth, development and defense responses. Here we describe the key features of plant endosomes and their differences from those of other organisms and discuss the role of these organelles in cell polarity and signaling pathways.
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70
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Lerich A, Hillmer S, Langhans M, Scheuring D, van Bentum P, Robinson DG. ER Import Sites and Their Relationship to ER Exit Sites: A New Model for Bidirectional ER-Golgi Transport in Higher Plants. FRONTIERS IN PLANT SCIENCE 2012; 3:143. [PMID: 22876251 PMCID: PMC3410614 DOI: 10.3389/fpls.2012.00143] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Accepted: 06/12/2012] [Indexed: 05/08/2023]
Abstract
Per definition, ER exit sites are COPII vesiculation events at the surface of the ER and in higher plants are only visualizable in the electron microscope through cryofixation techniques. Fluorescent COPII labeling moves with Golgi stacks and locates to the interface between the ER and the Golgi. In contrast, the domain of the ER where retrograde COPI vesicles fuse, i.e., ER import sites (ERIS), has remained unclear. To identify ERIS we have employed ER-located SNAREs and tethering factors. We screened several SNAREs (SYP81, the SYP7 family, and USE1) to find a SNARE whose overexpression did not disrupt ER-Golgi traffic and which gave rise to discrete fluorescent punctae when expressed with an XFP tag. Only the Qc-SNARE SYP72 fulfilled these criteria. When coexpressed with SYP72-YFP, both the type I-membrane protein RFP-p24δ5 and the luminal marker CFP-HDEL whose ER localization are due to an efficient COPI-mediated recycling, form nodules along the tubular ER network. SYP72-YFP colocalizes with these nodules which are not seen when RFP-p24δ5 or CFP-HDEL is expressed alone or when SYP72-YFP is coexpressed with a mutant form of RFP-p24δ5 that cannot exit the ER. SYP72-YFP does not colocalize with Golgi markers, except when the Golgi stacks are immobilized through actin depolymerization. Endogenous SYP7 SNAREs, also colocalize with immobilized COPII/Golgi. In contrast, XFP-tagged versions of plant homologs to TIP20 of the Dsl1 COPI-tethering factor complex, and the COPII-tethering factor p115 colocalize perfectly with Golgi stacks irrespective of the motile status. These data suggest that COPI vesicle fusion with the ER is restricted to periods when Golgi stacks are stationary, but that when moving both COPII and COPI vesicles are tethered and collect in the ER-Golgi interface. Thus, the Golgi stack and an associated domain of the ER thereby constitute a mobile secretory and recycling unit: a unique feature in eukaryotic cells.
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Affiliation(s)
- Alexander Lerich
- Department of Plant Cell Biology, Centre for Organismal Studies, University of HeidelbergHeidelberg, Germany
| | - Stefan Hillmer
- Department of Plant Cell Biology, Centre for Organismal Studies, University of HeidelbergHeidelberg, Germany
| | - Markus Langhans
- Department of Plant Cell Biology, Centre for Organismal Studies, University of HeidelbergHeidelberg, Germany
| | - David Scheuring
- Department of Plant Cell Biology, Centre for Organismal Studies, University of HeidelbergHeidelberg, Germany
| | - Paulien van Bentum
- Department of Plant Cell Biology, Centre for Organismal Studies, University of HeidelbergHeidelberg, Germany
| | - David G. Robinson
- Department of Plant Cell Biology, Centre for Organismal Studies, University of HeidelbergHeidelberg, Germany
- *Correspondence: David G. Robinson, Department Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 230, D-69120 Heidelberg, Germany. e-mail:
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71
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Reyes FC, Buono R, Otegui MS. Plant endosomal trafficking pathways. CURRENT OPINION IN PLANT BIOLOGY 2011; 14:666-73. [PMID: 21821464 DOI: 10.1016/j.pbi.2011.07.009] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 06/29/2011] [Accepted: 07/12/2011] [Indexed: 05/21/2023]
Abstract
Endosomes regulate both the recycling and degradation of plasma membrane (PM) proteins, thereby modulating many cellular responses triggered at the cell surface. Endosomes also play a role in the biosynthetic pathway by taking proteins to the vacuole and recycling vacuolar cargo receptors. In plants, the trans-Golgi network (TGN) acts as an early/recycling endosome whereas prevacuolar compartments/multivesicular bodies (MVBs) take PM proteins to the vacuole for degradation. Recent studies have demonstrated that some of the molecular complexes that mediate endosomal trafficking, such as the retromer, the ADP-ribosylation factor (ARF) machinery, and the Endosomal Sorting Complexes Required for Transport (ESCRTs) have both conserved and specialized functions in plants. Whereas there is disagreement on the subcellular localization of the plant retromer, its function in recycling vacuolar sorting receptors (VSRs) and modulating the trafficking of PM proteins has been well established. Studies on Arabidopsis ESCRT components highlight the essential role of this complex in cytokinesis, plant development, and vacuolar organization. In addition, post-translational modifications of plant PM proteins, such as phosphorylation and ubiquitination, have been demonstrated to act as sorting signals for endosomal trafficking.
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Affiliation(s)
- Francisca C Reyes
- Department of Botany, University of Wisconsin-Madison, Madison, WI 53706, United States
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72
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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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73
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Scheuring D, Viotti C, Krüger F, Künzl F, Sturm S, Bubeck J, Hillmer S, Frigerio L, Robinson DG, Pimpl P, Schumacher K. Multivesicular bodies mature from the trans-Golgi network/early endosome in Arabidopsis. THE PLANT CELL 2011; 23:3463-81. [PMID: 21934143 PMCID: PMC3203422 DOI: 10.1105/tpc.111.086918] [Citation(s) in RCA: 200] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2011] [Revised: 08/19/2011] [Accepted: 08/31/2011] [Indexed: 05/17/2023]
Abstract
The plant trans-Golgi network/early endosome (TGN/EE) is a major hub for secretory and endocytic trafficking with complex molecular mechanisms controlling sorting and transport of cargo. Vacuolar transport from the TGN/EE to multivesicular bodies/late endosomes (MVBs/LEs) is assumed to occur via clathrin-coated vesicles, although direct proof for their participation is missing. Here, we present evidence that post-TGN transport toward lytic vacuoles occurs independently of clathrin and that MVBs/LEs are derived from the TGN/EE through maturation. We show that the V-ATPase inhibitor concanamycin A significantly reduces the number of MVBs and causes TGN and MVB markers to colocalize in Arabidopsis thaliana roots. Ultrastructural analysis reveals the formation of MVBs from the TGN/EE and their fusion with the vacuole. The localization of the ESCRT components VPS28, VPS22, and VPS2 at the TGN/EE and MVBs/LEs indicates that the formation of intraluminal vesicles starts already at the TGN/EE. Accordingly, a dominant-negative mutant of VPS2 causes TGN and MVB markers to colocalize and blocks vacuolar transport. RNA interference-mediated knockdown of the annexin ANNAT3 also yields the same phenotype. Together, these data indicate that MVBs originate from the TGN/EE in a process that requires the action of ESCRT for the formation of intraluminal vesicles and annexins for the final step of releasing MVBs as a transport carrier to the vacuole.
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Affiliation(s)
- David Scheuring
- Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany
| | - Corrado Viotti
- Developmental Biology of Plants, Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany
| | - Falco Krüger
- Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany
| | - Fabian Künzl
- Developmental Genetics, Centre for Plant Molecular Biology, University of Tübingen, 72076 Tuebingen, Germany
| | - Silke Sturm
- Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany
| | - Julia Bubeck
- Developmental Biology of Plants, Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany
| | - Stefan Hillmer
- Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany
| | - Lorenzo Frigerio
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - David G. Robinson
- Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany
| | - Peter Pimpl
- Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany
- Developmental Genetics, Centre for Plant Molecular Biology, University of Tübingen, 72076 Tuebingen, Germany
- Address correspondence to
| | - Karin Schumacher
- Developmental Biology of Plants, Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany
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74
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Abstract
Being deeply connected to signalling, cell dynamics, growth, regulation, and defence, endocytic processes are linked to almost all aspects of cell life and disease. In this review, we focus on endosomes in the classical endocytic pathway, and on the programme of changes that lead to the formation and maturation of late endosomes/multivesicular bodies. The maturation programme entails a dramatic transformation of these dynamic organelles disconnecting them functionally and spatially from early endosomes and preparing them for their unidirectional role as a feeder pathway to lysosomes.
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75
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Bröcker C, Engelbrecht-Vandré S, Ungermann C. Multisubunit tethering complexes and their role in membrane fusion. Curr Biol 2011; 20:R943-52. [PMID: 21056839 DOI: 10.1016/j.cub.2010.09.015] [Citation(s) in RCA: 166] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Protein trafficking within eukaryotic cells depends on vesicular carriers that fuse with organelles to deliver their lipid and protein content. Cells have developed an elaborate system to capture vesicles at organelles that involves the action of Rab GTPases and tethers. Vesicle fusion then takes place with the help of SNARE proteins. In this review we focus on the role of multisubunit tethering complexes of eukaryotic cells. In particular, we discuss the tethering complexes of the secretory pathway and the endolysosomal system and highlight recent evidence for the role of these complexes in interaction with Rabs, coat recognition and cooperation with SNAREs during the fusion cascade.
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Affiliation(s)
- Cornelia Bröcker
- University of Osnabrück, Department of Biology/Chemistry, Barbarastrasse 13, 49076 Osnabrück, Germany
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76
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Park M, Jürgens G. Membrane traffic and fusion at post-Golgi compartments. FRONTIERS IN PLANT SCIENCE 2011; 2:111. [PMID: 22645561 PMCID: PMC3355779 DOI: 10.3389/fpls.2011.00111] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Accepted: 12/19/2011] [Indexed: 05/18/2023]
Abstract
Complete sequencing of the Arabidopsis genome a decade ago has facilitated the functional analysis of various biological processes including membrane traffic by which many proteins are delivered to their sites of action and turnover. In particular, membrane traffic between post-Golgi compartments plays an important role in cell signaling, taking care of receptor-ligand interaction and inactivation, which requires secretion, endocytosis, and recycling or targeting to the vacuole for degradation. Here, we discuss recent studies that address the identity of post-Golgi compartments, the machinery involved in traffic and fusion or functionally characterized cargo proteins that are delivered to or pass through post-Golgi compartments. We also provide an outlook on future challenges in this area of research.
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Affiliation(s)
- Misoon Park
- Entwicklungsgenetik, Zentrum für Molekularbiologie der Pflanzen, University of TübingenTübingen, Germany
| | - Gerd Jürgens
- Entwicklungsgenetik, Zentrum für Molekularbiologie der Pflanzen, University of TübingenTübingen, Germany
- *Correspondence: Gerd Jürgens, Entwicklungsgenetik, Zentrum für Molekularbiologie der Pflanzen, University of Tübingen, Auf der Morgenstelle 3, 72076 Tübingen, Germany. e-mail:
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Pourcher M, Santambrogio M, Thazar N, Thierry AM, Fobis-Loisy I, Miège C, Jaillais Y, Gaude T. Analyses of sorting nexins reveal distinct retromer-subcomplex functions in development and protein sorting in Arabidopsis thaliana. THE PLANT CELL 2010; 22:3980-91. [PMID: 21156856 PMCID: PMC3027177 DOI: 10.1105/tpc.110.078451] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Revised: 10/26/2010] [Accepted: 11/24/2010] [Indexed: 05/18/2023]
Abstract
Sorting nexins (SNXs) are conserved eukaryotic proteins that associate with three types of vacuolar protein sorting (VPS) proteins to form the retromer complex. How SNXs act in this complex and whether they might work independently of the retromer remains elusive. Here, we show by genetic and cell imaging approaches that the Arabidopsis thaliana SNX1 protein recruits SNX2 at the endosomal membrane, a process required for SNX1-SNX2 dimer activity. We report that, in contrast with the mammalian retromer, SNXs are dispensable for membrane binding and function of the retromer complex. We also show that VPS retromer components can work with or independently of SNXs in the trafficking of seed storage proteins, which reveals distinct functions for subcomplexes of the plant retromer. Finally, we provide compelling evidence that the combined loss of function of SNXs and VPS29 leads to embryo or seedling lethality, underlining the essential role of these proteins in development.
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Affiliation(s)
- Mikael Pourcher
- Université de Lyon, F-69007 Lyon, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5667, Institut Fédératif de Recherche 128, F-69342 Lyon, France
- Ecole Normale Supérieure de Lyon, F-69342 Lyon, France
- Institut National de la Recherche Agronomique, F-69364 Lyon, France
- Université Lyon 1, F-69622 Villeurbanne, France
| | - Martina Santambrogio
- Université de Lyon, F-69007 Lyon, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5667, Institut Fédératif de Recherche 128, F-69342 Lyon, France
- Ecole Normale Supérieure de Lyon, F-69342 Lyon, France
- Institut National de la Recherche Agronomique, F-69364 Lyon, France
- Université Lyon 1, F-69622 Villeurbanne, France
| | - Nelcy Thazar
- Université de Lyon, F-69007 Lyon, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5667, Institut Fédératif de Recherche 128, F-69342 Lyon, France
- Ecole Normale Supérieure de Lyon, F-69342 Lyon, France
- Institut National de la Recherche Agronomique, F-69364 Lyon, France
- Université Lyon 1, F-69622 Villeurbanne, France
| | - Anne-Marie Thierry
- Université de Lyon, F-69007 Lyon, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5667, Institut Fédératif de Recherche 128, F-69342 Lyon, France
- Ecole Normale Supérieure de Lyon, F-69342 Lyon, France
- Institut National de la Recherche Agronomique, F-69364 Lyon, France
- Université Lyon 1, F-69622 Villeurbanne, France
| | - Isabelle Fobis-Loisy
- Université de Lyon, F-69007 Lyon, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5667, Institut Fédératif de Recherche 128, F-69342 Lyon, France
- Ecole Normale Supérieure de Lyon, F-69342 Lyon, France
- Institut National de la Recherche Agronomique, F-69364 Lyon, France
- Université Lyon 1, F-69622 Villeurbanne, France
| | - Christine Miège
- Université de Lyon, F-69007 Lyon, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5667, Institut Fédératif de Recherche 128, F-69342 Lyon, France
- Ecole Normale Supérieure de Lyon, F-69342 Lyon, France
- Institut National de la Recherche Agronomique, F-69364 Lyon, France
- Université Lyon 1, F-69622 Villeurbanne, France
| | - Yvon Jaillais
- Université de Lyon, F-69007 Lyon, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5667, Institut Fédératif de Recherche 128, F-69342 Lyon, France
- Ecole Normale Supérieure de Lyon, F-69342 Lyon, France
- Institut National de la Recherche Agronomique, F-69364 Lyon, France
- Université Lyon 1, F-69622 Villeurbanne, France
| | - Thierry Gaude
- Université de Lyon, F-69007 Lyon, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5667, Institut Fédératif de Recherche 128, F-69342 Lyon, France
- Ecole Normale Supérieure de Lyon, F-69342 Lyon, France
- Institut National de la Recherche Agronomique, F-69364 Lyon, France
- Université Lyon 1, F-69622 Villeurbanne, France
- Address correspondence to
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78
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Schumacher K, Krebs M. The V-ATPase: small cargo, large effects. CURRENT OPINION IN PLANT BIOLOGY 2010; 13:724-30. [PMID: 20801076 DOI: 10.1016/j.pbi.2010.07.003] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Revised: 07/20/2010] [Accepted: 07/30/2010] [Indexed: 05/18/2023]
Abstract
About 30 years ago seminal reports of anion-sensitive proton-pumping activity associated with microsomal membranes initiated research on the plant vacuolar-type H(+)-ATPase (V-ATPase, VHA). Since, it has been firmly established that these complex molecular machines are essential for what can be defined as cellular logistics. In a eukaryotic cell, the flow of goods between compartments is achieved either by protein-mediated membrane transport or via vesicular trafficking. Over the past years, it has become increasingly clear that V-ATPases do not only energize secondary active transport but are also important regulators of membrane trafficking.
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Affiliation(s)
- Karin Schumacher
- Heidelberg Institute for Plant Sciences (HIP), Universität Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany.
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79
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Foresti O, Gershlick DC, Bottanelli F, Hummel E, Hawes C, Denecke J. A recycling-defective vacuolar sorting receptor reveals an intermediate compartment situated between prevacuoles and vacuoles in tobacco. THE PLANT CELL 2010; 22:3992-4008. [PMID: 21177482 PMCID: PMC3027165 DOI: 10.1105/tpc.110.078436] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Revised: 10/04/2010] [Accepted: 11/11/2010] [Indexed: 05/18/2023]
Abstract
Plant vacuolar sorting receptors (VSRs) display cytosolic Tyr motifs (YMPL) for clathrin-mediated anterograde transport to the prevacuolar compartment. Here, we show that the same motif is also required for VSR recycling. A Y612A point mutation in Arabidopsis thaliana VSR2 leads to a quantitative shift in VSR2 steady state levels from the prevacuolar compartment to the trans-Golgi network when expressed in Nicotiana tabacum. By contrast, the L615A mutant VSR2 leaks strongly to vacuoles and accumulates in a previously undiscovered compartment. The latter is shown to be distinct from the Golgi stacks, the trans-Golgi network, and the prevacuolar compartment but is characterized by high concentrations of soluble vacuolar cargo and the rab5 GTPase Rha1(RabF2a). The results suggest that the prevacuolar compartment matures by gradual receptor depletion, leading to the formation of a late prevacuolar compartment situated between the prevacuolar compartment and the vacuole.
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Affiliation(s)
- Ombretta Foresti
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - David C. Gershlick
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Francesca Bottanelli
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Eric Hummel
- School of Life Sciences, Oxford Brookes, Oxford OX3 0BP, United Kingdom
| | - Chris Hawes
- School of Life Sciences, Oxford Brookes, Oxford OX3 0BP, United Kingdom
| | - Jürgen Denecke
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
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80
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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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81
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Zouhar J, Muñoz A, Rojo E. Functional specialization within the vacuolar sorting receptor family: VSR1, VSR3 and VSR4 sort vacuolar storage cargo in seeds and vegetative tissues. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 64:577-88. [PMID: 20807215 DOI: 10.1111/j.1365-313x.2010.04349.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Two different gene families have been proposed to act as sorting receptors for vacuolar storage cargo in plants: the vacuolar sorting receptors (VSRs) and the receptor homology-transmembrane-RING H2 domain proteins (RMRs). However, functional data on these genes is scarce and the identity of the sorting receptor for storage proteins remains controversial. Through a genetic screen we have identified the mtv2 mutant, which is defective in vacuolar transport of the storage cargo VAC2 in shoot apices. Map-based cloning revealed that mtv2 is a loss of function allele of the VSR4 gene. We show that VSR1, VSR3 and VSR4, but not the remaining VSRs or RMRs, participate in vacuolar sorting of VAC2 in vegetative tissues, and 12S globulins and 2S albumins in seeds, an activity that is essential for seedling germination vigor. Finally, we demonstrate that the functional diversification in the VSR family results from divergent expression patterns and also from distinct sorting activities of the family members.
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Affiliation(s)
- Jan Zouhar
- Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología-CSIC, E-28049 Madrid, Spain
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82
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Shahriari M, Keshavaiah C, Scheuring D, Sabovljevic A, Pimpl P, Häusler RE, Hülskamp M, Schellmann S. The AAA-type ATPase AtSKD1 contributes to vacuolar maintenance of Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 64:71-85. [PMID: 20663085 DOI: 10.1111/j.1365-313x.2010.04310.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The vacuole is the most prominent organelle of plant cells. Despite its importance for many physiological and developmental aspects of plant life, little is known about its biogenesis and maintenance. Here we show that Arabidopsis plants expressing a dominant-negative version of the AAA (ATPase associated with various cellular activities) ATPase AtSKD1 (SUPPRESSOR OF K+ TRANSPORT GROWTH DEFECT1) under the control of the trichome-specific GLABRA2 (GL2) promoter exhibit normal vacuolar development in early stages of trichome development. Shortly after its formation, however, the large central vacuole is fragmented and finally disappears completely. Secretion assays with amylase fused to the vacuolar sorting signal of Sporamin show that dominant-negative AtSKD1 inhibits vacuolar trafficking of the reporter that is instead secreted. In addition, trichomes expressing dominant-negative AtSKD1 frequently contain multiple nuclei. Our results suggest that AtSKD1 contributes to vacuolar protein trafficking and thereby to the maintenance of the large central vacuole of plant cells, and might play a role in cell-cycle regulation.
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Affiliation(s)
- Mojgan Shahriari
- Biozentrum Köln, University of Cologne, Zülpicher Street 47 b, 50674 Cologne, Germany
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83
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Thellmann M, Rybak K, Thiele K, Wanner G, Assaad FF. Tethering factors required for cytokinesis in Arabidopsis. PLANT PHYSIOLOGY 2010; 154:720-32. [PMID: 20713617 PMCID: PMC2948999 DOI: 10.1104/pp.110.154286] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
At the end of the cell cycle, the nascent cross wall is laid down within a transient membrane compartment referred to as the cell plate. Tethering factors, which act by capturing vesicles and holding them in the vicinity of their target membranes, are likely to play an important role in the first stages of cell plate assembly. Factors required for cell plate biogenesis, however, remain to be identified. In this study, we used a reverse genetic screen to isolate tethering factors required for cytokinesis in Arabidopsis (Arabidopsis thaliana). We focused on the TRAPPI and TRAPPII (for transport protein particle) tethering complexes, which are thought to be required for the flow of traffic through the Golgi and for trans-Golgi network function, as well as on the GARP complex, thought to be required for the tethering of endocytotic vesicles to the trans-Golgi network. We found weak cytokinesis defects in some TRAPPI mutants and strong cytokinesis defects in all the TRAPPII lines we surveyed. Indeed, four insertion lines at the TRAPPII locus AtTRS120 had canonical cytokinesis-defective seedling-lethal phenotypes, including cell wall stubs and incomplete cross walls. Confocal and electron microscopy showed that in trs120 mutants, vesicles accumulated at the equator of dividing cells yet failed to assemble into a cell plate. This shows that AtTRS120 is required for cell plate biogenesis. In contrast to the TRAPP complexes, we found no conclusive evidence for cytokinesis defects in seven GARP insertion lines. We discuss the implications of these findings for the origin and identity of cell plate membranes.
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84
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Grunewald W, Friml J. The march of the PINs: developmental plasticity by dynamic polar targeting in plant cells. EMBO J 2010; 29:2700-14. [PMID: 20717140 DOI: 10.1038/emboj.2010.181] [Citation(s) in RCA: 201] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Accepted: 07/09/2010] [Indexed: 11/09/2022] Open
Abstract
Development of plants and their adaptive capacity towards ever-changing environmental conditions largely depend on the spatial distribution of the plant hormone auxin. At the cellular level, various internal and external signals are translated into specific changes in the polar, subcellular localization of auxin transporters from the PIN family thereby directing and redirecting the intercellular fluxes of auxin. The current model of polar targeting of PIN proteins towards different plasma membrane domains encompasses apolar secretion of newly synthesized PINs followed by endocytosis and recycling back to the plasma membrane in a polarized manner. In this review, we follow the subcellular march of the PINs and highlight the cellular and molecular mechanisms behind polar foraging and subcellular trafficking pathways. Also, the entry points for different signals and regulations including by auxin itself will be discussed within the context of morphological and developmental consequences of polar targeting and subcellular trafficking.
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Affiliation(s)
- Wim Grunewald
- Department of Plant Systems Biology, VIB, Technologiepark, Gent, Belgium
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85
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Saint-Jean B, Seveno-Carpentier E, Alcon C, Neuhaus JM, Paris N. The cytosolic tail dipeptide Ile-Met of the pea receptor BP80 is required for recycling from the prevacuole and for endocytosis. THE PLANT CELL 2010; 22:2825-37. [PMID: 20807880 PMCID: PMC2947187 DOI: 10.1105/tpc.109.072215] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2009] [Revised: 06/24/2010] [Accepted: 08/05/2010] [Indexed: 05/18/2023]
Abstract
Pea (Pisum sativum) BP80 is a vacuolar sorting receptor for soluble proteins and has a cytosolic domain essential for its intracellular trafficking between the trans-Golgi network and the prevacuole. Based on mammalian knowledge, we introduced point mutations in the cytosolic region of the receptor and produced chimeras of green fluorescent protein fused to the transmembrane domain of pea BP80 along with the modified cytosolic tails. By analyzing the subcellular location of these chimera, we found that mutating Glu-604, Asp-616, or Glu-620 had mild effects, whereas mutating the Tyr motif partially redistributed the chimera to the plasma membrane. Replacing both Ile-608 and Met-609 by Ala (IMAA) led to a massive redistribution of fluorescence to the vacuole, indicating that recycling is impaired. When the chimera uses the alternative route, the IMAA mutation led to a massive accumulation at the plasma membrane. Using Arabidopsis thaliana plants expressing a fluorescent reporter with the full-length sequence of At VSR4, we demonstrated that the receptor undergoes brefeldin A-sensitive endocytosis. We conclude that the receptors use two pathways, one leading directly to the lytic vacuole and the other going via the plasma membrane, and that the Ileu-608 Met-609 motif has a role in the retrieval step in both pathways.
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Affiliation(s)
- Bruno Saint-Jean
- Laboratoire de Physiologie et Biotechnologie des Algues, Institut Français de Recherche pour l'Exploitation de la Mer, 44311 Nantes Cedex 03, France
| | - Emilie Seveno-Carpentier
- Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, Unité Mixte de Recherche 5004, Centre National de la Recherche Scientifique/Unité Mixte de Recherche 0386, Institut National de la Recherche Agronomique/Montpellier SupAgro/Université Montpellier 2, F-34060 Montpellier Cedex 1, France
| | - Carine Alcon
- Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, Unité Mixte de Recherche 5004, Centre National de la Recherche Scientifique/Unité Mixte de Recherche 0386, Institut National de la Recherche Agronomique/Montpellier SupAgro/Université Montpellier 2, F-34060 Montpellier Cedex 1, France
| | - Jean-Marc Neuhaus
- Laboratoire de Biologie Moléculaire et Cellulaire, Université de Neuchâtel, CH-2009 Neuchâtel, Switzerland
| | - Nadine Paris
- Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, Unité Mixte de Recherche 5004, Centre National de la Recherche Scientifique/Unité Mixte de Recherche 0386, Institut National de la Recherche Agronomique/Montpellier SupAgro/Université Montpellier 2, F-34060 Montpellier Cedex 1, France
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86
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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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87
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Viotti C, Bubeck J, Stierhof YD, Krebs M, Langhans M, van den Berg W, van Dongen W, Richter S, Geldner N, Takano J, Jürgens G, de Vries SC, Robinson DG, Schumacher K. Endocytic and secretory traffic in Arabidopsis merge in the trans-Golgi network/early endosome, an independent and highly dynamic organelle. THE PLANT CELL 2010; 22:1344-57. [PMID: 20435907 PMCID: PMC2879741 DOI: 10.1105/tpc.109.072637] [Citation(s) in RCA: 350] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Revised: 03/22/2010] [Accepted: 04/09/2010] [Indexed: 05/17/2023]
Abstract
Plants constantly adjust their repertoire of plasma membrane proteins that mediates transduction of environmental and developmental signals as well as transport of ions, nutrients, and hormones. The importance of regulated secretory and endocytic trafficking is becoming increasingly clear; however, our knowledge of the compartments and molecular machinery involved is still fragmentary. We used immunogold electron microscopy and confocal laser scanning microscopy to trace the route of cargo molecules, including the BRASSINOSTEROID INSENSITIVE1 receptor and the REQUIRES HIGH BORON1 boron exporter, throughout the plant endomembrane system. Our results provide evidence that both endocytic and secretory cargo pass through the trans-Golgi network/early endosome (TGN/EE) and demonstrate that cargo in late endosomes/multivesicular bodies is destined for vacuolar degradation. Moreover, using spinning disc microscopy, we show that TGN/EEs move independently and are only transiently associated with an individual Golgi stack.
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Affiliation(s)
- Corrado Viotti
- Department of Cell Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, 69120 Heidelberg, Germany
| | - Julia Bubeck
- Department of Developmental Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, 69120 Heidelberg, Germany
| | - York-Dieter Stierhof
- Microscopy Unit, Center for Plant Molecular Biology, University of Tübingen, 72076 Tübingen, Germany
| | - Melanie Krebs
- Department of Developmental Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, 69120 Heidelberg, Germany
| | - Markus Langhans
- Department of Cell Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, 69120 Heidelberg, Germany
| | - Willy van den Berg
- Laboratory of Biochemistry, Wageningen University, 6703 HA Wageningen, The Netherlands
| | - Walter van Dongen
- Laboratory of Biochemistry, Wageningen University, 6703 HA Wageningen, The Netherlands
| | - Sandra Richter
- Developmental Genetics, Center for Plant Molecular Biology, University of Tübingen, 72076 Tübingen, Germany
| | - Niko Geldner
- Department of Plant Molecular Biology, University of Lausanne, 1015 Lausanne, Switzerland
| | - Junpei Takano
- Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Sapporo 060-8589, Japan
| | - Gerd Jürgens
- Developmental Genetics, Center for Plant Molecular Biology, University of Tübingen, 72076 Tübingen, Germany
| | - Sacco C. de Vries
- Laboratory of Biochemistry, Wageningen University, 6703 HA Wageningen, The Netherlands
| | - David G. Robinson
- Department of Cell Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, 69120 Heidelberg, Germany
| | - Karin Schumacher
- Department of Developmental Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, 69120 Heidelberg, Germany
- Address correspondence to
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