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Huang C, Sede AR, Elvira-González L, Yan Y, Rodriguez ME, Mutterer J, Boutant E, Shan L, Heinlein M. dsRNA-induced immunity targets plasmodesmata and is suppressed by viral movement proteins. THE PLANT CELL 2023; 35:3845-3869. [PMID: 37378592 PMCID: PMC10533371 DOI: 10.1093/plcell/koad176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 05/24/2023] [Accepted: 05/23/2023] [Indexed: 06/29/2023]
Abstract
Emerging evidence indicates that in addition to its well-recognized functions in antiviral RNA silencing, dsRNA elicits pattern-triggered immunity (PTI), likely contributing to plant resistance against virus infections. However, compared to bacterial and fungal elicitor-mediated PTI, the mode-of-action and signaling pathway of dsRNA-induced defense remain poorly characterized. Here, using multicolor in vivo imaging, analysis of GFP mobility, callose staining, and plasmodesmal marker lines in Arabidopsis thaliana and Nicotiana benthamiana, we show that dsRNA-induced PTI restricts the progression of virus infection by triggering callose deposition at plasmodesmata, thereby likely limiting the macromolecular transport through these cell-to-cell communication channels. The plasma membrane-resident SOMATIC EMBRYOGENESIS RECEPTOR-LIKE KINASE 1, the BOTRYTIS INDUCED KINASE1/AVRPPHB SUSCEPTIBLE1-LIKE KINASE1 kinase module, PLASMODESMATA-LOCATED PROTEINs 1/2/3, as well as CALMODULIN-LIKE 41 and Ca2+ signals are involved in the dsRNA-induced signaling leading to callose deposition at plasmodesmata and antiviral defense. Unlike the classical bacterial elicitor flagellin, dsRNA does not trigger a detectable reactive oxygen species (ROS) burst, substantiating the idea that different microbial patterns trigger partially shared immune signaling frameworks with distinct features. Likely as a counter strategy, viral movement proteins from different viruses suppress the dsRNA-induced host response leading to callose deposition to achieve infection. Thus, our data support a model in which plant immune signaling constrains virus movement by inducing callose deposition at plasmodesmata and reveals how viruses counteract this layer of immunity.
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Affiliation(s)
- Caiping Huang
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, 67000 Strasbourg, France
| | - Ana Rocío Sede
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, 67000 Strasbourg, France
| | - Laura Elvira-González
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, 67000 Strasbourg, France
| | - Yan Yan
- Department of Biochemistry and Biophysics, College of Agriculture and Life Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Miguel Eduardo Rodriguez
- Department of Biochemistry and Biophysics, College of Agriculture and Life Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Jérôme Mutterer
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, 67000 Strasbourg, France
| | - Emmanuel Boutant
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, 67000 Strasbourg, France
| | - Libo Shan
- Department of Biochemistry and Biophysics, College of Agriculture and Life Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Manfred Heinlein
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, 67000 Strasbourg, France
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2
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Peña EJ, Heinlein M. In Vivo Visualization of Mobile mRNA Particles in Plants Using BglG. Methods Mol Biol 2022; 2457:411-426. [PMID: 35349157 DOI: 10.1007/978-1-0716-2132-5_28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Cells have developed mechanisms for cytoplasmic RNA transport and localization that participate in the regulation and subcellular localization of protein synthesis. In addition, plants can exchange RNA molecules between cells through plasmodesmata and to distant tissues in the phloem. These mechanisms are hijacked by RNA viruses to establish their replication complexes and to disseminate their genomes throughout the plant organism with the help of virus-encoded movement proteins (MP). Live imaging of RNA molecules is a fundamental approach to understand the regulation and molecular basis of these processes. The most widely used experimental systems for the in vivo visualization of genetically encoded RNA molecules are based on fluorescently tagged RNA binding proteins that bind to specific motifs inserted into the RNA, thus allowing the tracking of the specific RNA molecule by fluorescent microscopy. Recently, we developed the use of the E. coli RNA binding protein BglG for the imaging of RNAs tagged with BglG-binding sites in planta. We describe here the detailed method by which we use this in vivo RNA tagging system for the real-time imaging of Tobacco mosaic virus (TMV) MP mRNA.
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Affiliation(s)
- Eduardo J Peña
- Instituto de Biotecnología y Biología Molecular (IBBM), Facultad de Ciencias Exactas-UNLP, CONICET, La Plata, Argentina
| | - Manfred Heinlein
- Institut de Biologie Moléculaire des Plantes (IBMP), CNRS, Université de Strasbourg, Strasbourg, France.
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Pitzalis N, Heinlein M. The roles of membranes and associated cytoskeleton in plant virus replication and cell-to-cell movement. JOURNAL OF EXPERIMENTAL BOTANY 2017; 69:117-132. [PMID: 29036578 DOI: 10.1093/jxb/erx334] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The infection of plants by viruses depends on cellular mechanisms that support the replication of the viral genomes, and the cell-to-cell and systemic movement of the virus via plasmodesmata (PD) and the connected phloem. While the propagation of some viruses requires the conventional endoplasmic reticulum (ER)-Golgi pathway, others replicate and spread between cells in association with the ER and are independent of this pathway. Using selected viruses as examples, this review re-examines the involvement of membranes and the cytoskeleton during virus infection and proposes potential roles of class VIII myosins and membrane-tethering proteins in controlling viral functions at specific ER subdomains, such as cortical microtubule-associated ER sites, ER-plasma membrane contact sites, and PD.
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Plant virus replication and movement. Virology 2015; 479-480:657-71. [DOI: 10.1016/j.virol.2015.01.025] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 01/19/2015] [Accepted: 01/28/2015] [Indexed: 01/10/2023]
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Abstract
The symplastic communication network established by plasmodesmata (PD) and connected phloem provides an essential pathway for spatiotemporal intercellular signaling in plant development but is also exploited by viruses for moving their genomes between cells in order to infect plants systemically. Virus movement depends on virus-encoded movement proteins (MPs) that target PD and therefore represent important keys to the cellular mechanisms underlying the intercellular trafficking of viruses and other macromolecules. Viruses and their MPs have evolved different mechanisms for intracellular transport and interaction with PD. Some viruses move from cell to cell by interacting with cellular mechanisms that control the size exclusion limit of PD whereas other viruses alter the PD architecture through assembly of specialized transport structures within the channel. Some viruses move between cells in the form of assembled virus particles whereas other viruses may interact with nucleic acid transport mechanisms to move their genomes in a non-encapsidated form. Moreover, whereas several viruses rely on the secretory pathway to target PD, other viruses interact with the cortical endoplasmic reticulum and associated cytoskeleton to spread infection. This chapter provides an introduction into viruses and their role in studying the diverse cellular mechanisms involved in intercellular PD-mediated macromolecular trafficking.
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Affiliation(s)
- Manfred Heinlein
- Institut de Biologie Moléculaire des Plantes (IBMP), Centre National de la Recherche Scientifique (CNRS), 12 rue du Général Zimmer, 67084, Strasbourg, France,
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6
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Sun Y, Periasamy A. Localizing protein-protein interactions in living cells using fluorescence lifetime imaging microscopy. Methods Mol Biol 2015; 1251:83-107. [PMID: 25391796 DOI: 10.1007/978-1-4939-2080-8_6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In the past decade, advances in fluorescence lifetime imaging have extensively applied in the life sciences, from fundamental biological investigations to advanced clinical diagnosis. Fluorescence lifetime imaging microscopy (FLIM) is now routinely used in the biological sciences to monitor dynamic signaling events inside living cells, e.g., Protein-Protein interactions. In this chapter, we describe the calibration of both time-correlated single-photon counting (TCSPC) and frequency domain (FD) FLIM systems and the acquisition and analysis of FLIM-FRET data for investigating Protein-Protein interactions in living cells.
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Affiliation(s)
- Yuansheng Sun
- W.M. Keck Center for Cellular Imaging, Biology, University of Virginia, B005 Physical and Life Sciences Building, White Head Road, Charlottesville, VA, 22904, USA
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Amari K, Di Donato M, Dolja VV, Heinlein M. Myosins VIII and XI play distinct roles in reproduction and transport of tobacco mosaic virus. PLoS Pathog 2014; 10:e1004448. [PMID: 25329993 PMCID: PMC4199776 DOI: 10.1371/journal.ppat.1004448] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 09/04/2014] [Indexed: 12/02/2022] Open
Abstract
Viruses are obligatory parasites that depend on host cellular factors for their replication as well as for their local and systemic movement to establish infection. Although myosin motors are thought to contribute to plant virus infection, their exact roles in the specific infection steps have not been addressed. Here we investigated the replication, cell-to-cell and systemic spread of Tobacco mosaic virus (TMV) using dominant negative inhibition of myosin activity. We found that interference with the functions of three class VIII myosins and two class XI myosins significantly reduced the local and long-distance transport of the virus. We further determined that the inactivation of myosins XI-2 and XI-K affected the structure and dynamic behavior of the ER leading to aggregation of the viral movement protein (MP) and to a delay in the MP accumulation in plasmodesmata (PD). The inactivation of myosin XI-2 but not of myosin XI-K affected the localization pattern of the 126k replicase subunit and the level of TMV accumulation. The inhibition of myosins VIII-1, VIII-2 and VIII-B abolished MP localization to PD and caused its retention at the plasma membrane. These results suggest that class XI myosins contribute to the viral propagation and intracellular trafficking, whereas myosins VIII are specifically required for the MP targeting to and virus movement through the PD. Thus, TMV appears to recruit distinct myosins for different steps in the cell-to-cell spread of the infection.
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Affiliation(s)
- Khalid Amari
- Zürich-Basel Plant Science Center, Botany, Department of Environmental Sciences, University of Basel, Basel, Switzerland
| | - Martin Di Donato
- Zürich-Basel Plant Science Center, Botany, Department of Environmental Sciences, University of Basel, Basel, Switzerland
| | - Valerian V. Dolja
- Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon, United States of America
| | - Manfred Heinlein
- Zürich-Basel Plant Science Center, Botany, Department of Environmental Sciences, University of Basel, Basel, Switzerland
- Institut de Biologie Moléculaire des Plantes du CNRS, Université de Strasbourg, Strasbourg, France
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Role of the nucleocapsid region in HIV-1 Gag assembly as investigated by quantitative fluorescence-based microscopy. Virus Res 2014; 193:78-88. [PMID: 25016037 DOI: 10.1016/j.virusres.2014.06.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Revised: 06/17/2014] [Accepted: 06/17/2014] [Indexed: 11/19/2022]
Abstract
The Gag precursor of HIV-1, formed of the four proteic regions matrix (MA), capsid (CA), nucleocapsid (NC) and p6, orchestrates virus morphogenesis. This complex process relies on three major interactions, NC-RNA acting as a scaffold, CA-CA and MA-membrane that targets assembly to the plasma membrane (PM). The characterization of the molecular mechanism of retroviral assembly has extensively benefited from biochemical studies and more recently an important step forward was achieved with the use of fluorescence-based techniques and fluorescently labeled viral proteins. In this review, we summarize the findings obtained with such techniques, notably quantitative-based approaches, which highlight the role of the NC region in Gag assembly.
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Niehl A, Pasquier A, Ferriol I, Mély Y, Heinlein M. Comparison of the Oilseed rape mosaic virus and Tobacco mosaic virus movement proteins (MP) reveals common and dissimilar MP functions for tobamovirus spread. Virology 2014; 456-457:43-54. [PMID: 24889224 DOI: 10.1016/j.virol.2014.03.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 01/29/2014] [Accepted: 03/09/2014] [Indexed: 11/19/2022]
Abstract
Tobacco mosaic virus (TMV) is a longstanding model for studying virus movement and macromolecular transport through plasmodesmata (PD). Its movement protein (MP) interacts with cortical microtubule (MT)-associated ER sites (C-MERs) to facilitate the formation and transport of ER-associated viral replication complexes (VRCs) along the ER-actin network towards PD. To investigate whether this movement mechanism might be conserved between tobamoviruses, we compared the functions of Oilseed rape mosaic virus (ORMV) MP with those of MP(TMV). We show that MP(ORMV) supports TMV movement more efficiently than MP(TMV). Moreover, MP(ORMV) localizes to C-MERs like MP(TMV) but accumulates to lower levels and does not localize to larger inclusions/VRCs or along MTs, patterns regularly seen for MP(TMV). Our findings extend the role of C-MERs in viral cell-to-cell transport to a virus commonly used for functional genomics in Arabidopsis. Moreover, accumulation of tobamoviral MP in inclusions or along MTs is not required for virus movement.
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Affiliation(s)
- Annette Niehl
- Institut de Biologie Moléculaire des Plantes du CNRS (UPR 2357), Université de Strasbourg, 12 rue du Général Zimmer, 67000 Strasbourg, France; Zürich-Basel Plant Science Center, Department of Environmental Sciences, Botany, University of Basel, Hebelstrasse 1, 4056 Basel, Switzerland.
| | - Adrien Pasquier
- Institut de Biologie Moléculaire des Plantes du CNRS (UPR 2357), Université de Strasbourg, 12 rue du Général Zimmer, 67000 Strasbourg, France
| | - Inmaculada Ferriol
- Instituto Valenciano de Investigaciones Agrarias, 46113 Moncada, Valencia, Spain
| | - Yves Mély
- Laboratoire de Biophotonique et Pharmacologie, CNRS (UMR 7213), Université de Strasbourg, Faculté de Pharmacie, 74 route du Rhin, 67401 Illkirch, France
| | - Manfred Heinlein
- Institut de Biologie Moléculaire des Plantes du CNRS (UPR 2357), Université de Strasbourg, 12 rue du Général Zimmer, 67000 Strasbourg, France; Zürich-Basel Plant Science Center, Department of Environmental Sciences, Botany, University of Basel, Hebelstrasse 1, 4056 Basel, Switzerland.
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10
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Niehl A, Peña EJ, Amari K, Heinlein M. Microtubules in viral replication and transport. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 75:290-308. [PMID: 23379770 DOI: 10.1111/tpj.12134] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Revised: 01/29/2013] [Accepted: 01/31/2013] [Indexed: 05/05/2023]
Abstract
Viruses use and subvert host cell mechanisms to support their replication and spread between cells, tissues and organisms. Microtubules and associated motor proteins play important roles in these processes in animal systems, and may also play a role in plants. Although transport processes in plants are mostly actin based, studies, in particular with Tobacco mosaic virus (TMV) and its movement protein (MP), indicate direct or indirect roles of microtubules in the cell-to-cell spread of infection. Detailed observations suggest that microtubules participate in the cortical anchorage of viral replication complexes, in guiding their trafficking along the endoplasmic reticulum (ER)/actin network, and also in developing the complexes into virus factories. Microtubules also play a role in the plant-to-plant transmission of Cauliflower mosaic virus (CaMV) by assisting in the development of specific virus-induced inclusions that facilitate viral uptake by aphids. The involvement of microtubules in the formation of virus factories and of other virus-induced inclusions suggests the existence of aggresomal pathways by which plant cells recruit membranes and proteins into localized macromolecular assemblies. Although studies related to the involvement of microtubules in the interaction of viruses with plants focus on specific virus models, a number of observations with other virus species suggest that microtubules may have a widespread role in viral pathogenesis.
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Affiliation(s)
- Annette Niehl
- Zürich-Basel Plant Science Center, Botany, Department of Environmental Sciences, University of Basel, Hebelstrasse 1, CH-4056 Basel, Switzerland
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11
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Sun Y, Rombola C, Jyothikumar V, Periasamy A. Förster resonance energy transfer microscopy and spectroscopy for localizing protein-protein interactions in living cells. Cytometry A 2013; 83:780-93. [PMID: 23813736 DOI: 10.1002/cyto.a.22321] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Revised: 04/08/2013] [Accepted: 05/23/2013] [Indexed: 12/15/2022]
Abstract
The fundamental theory of Förster resonance energy transfer (FRET) was established in the 1940s. Its great power was only realized in the past 20 years after different techniques were developed and applied to biological experiments. This success was made possible by the availability of suitable fluorescent probes, advanced optics, detectors, microscopy instrumentation, and analytical tools. Combined with state-of-the-art microscopy and spectroscopy, FRET imaging allows scientists to study a variety of phenomena that produce changes in molecular proximity, thereby leading to many significant findings in the life sciences. In this review, we outline various FRET imaging techniques and their strengths and limitations; we also provide a biological model to demonstrate how to investigate protein-protein interactions in living cells using both intensity- and fluorescence lifetime-based FRET microscopy methods.
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Affiliation(s)
- Yuansheng Sun
- The W.M. Keck Center for Cellular Imaging (KCCI), Department of Biology, Physical and Life Sciences Building, University of Virginia, Charlottesville, Virginia
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12
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Peña EJ, Robles Luna G, Zanek MC, Borniego MB, Reyes CA, Heinlein M, García ML. Citrus psorosis and Mirafiori lettuce big-vein ophiovirus coat proteins localize to the cytoplasm and self interact in vivo. Virus Res 2012; 170:34-43. [DOI: 10.1016/j.virusres.2012.08.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Revised: 08/01/2012] [Accepted: 08/08/2012] [Indexed: 10/28/2022]
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13
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Heskes AM, Lincoln CN, Goodger JQD, Woodrow IE, Smith TA. Multiphoton fluorescence lifetime imaging shows spatial segregation of secondary metabolites in Eucalyptus secretory cavities. J Microsc 2012; 247:33-42. [PMID: 22394321 DOI: 10.1111/j.1365-2818.2011.03593.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Multiphoton fluorescence lifetime imaging provides an excellent tool for imaging deep within plant tissues while providing a means to distinguish between fluorophores with high spatial and temporal resolution. Ideal candidates for the application of multiphoton fluorescence lifetime imaging to plants are the embedded secretory cavities found in numerous species because they house complex mixtures of secondary metabolites within extracellular lumina. Previous investigations of this type of structure have been restricted by the use of sectioned material resulting in the loss of lumen contents and often disorganization of the delicate secretory cells; thus it is not known if there is spatial segregation of secondary metabolites within these structures. In this paper, we apply multiphoton fluorescence lifetime imaging to investigate the spatial arrangement of metabolites within intact secretory cavities isolated from Eucalyptus polybractea R.T. Baker leaves. The secretory cavities of this species are abundant (up to 10 000 per leaf), large (up to 6 nL) and importantly house volatile essential oil rich in the monoterpene 1,8-cineole, together with an immiscible, non-volatile component comprised largely of autofluorescent oleuropeic acid glucose esters. We have been able to optically section into the lumina of secretory cavities to a depth of ∼80 μm, revealing a unique spatial organization of cavity metabolites whereby the non-volatile component forms a layer between the secretory cells lining the lumen and the essential oil. This finding could be indicative of a functional role of the non-volatile component in providing a protective region of low diffusivity between the secretory cells and potentially autotoxic essential oil.
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Affiliation(s)
- A M Heskes
- School of Botany, University of Melbourne, Australia.
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14
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Peña EJ, Heinlein M. RNA transport during TMV cell-to-cell movement. FRONTIERS IN PLANT SCIENCE 2012; 3:193. [PMID: 22973280 PMCID: PMC3428586 DOI: 10.3389/fpls.2012.00193] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 08/06/2012] [Indexed: 05/08/2023]
Abstract
Studies during the last 25 years have provided increasing evidence for the ability of plants to support the cell-to-cell and systemic transport of RNA molecules and that this process plays a role in plant development and in the systemic orchestration of cellular responses against pathogens and other environmental challenges. Since RNA viruses exploit the cellular RNA transport machineries for spreading their genomes between cells they represent convenient models to investigate the underlying mechanisms. In this regard, the intercellular spread of Tobacco mosaic virus (TMV) has been studied for many years. The RNA of TMV moves cell-to-cell in a non-encapsidated form in a process depending on virus-encoded movement protein (MP). Here, we discuss the current state of the art in studies using TMV and its MP as a model for RNA transport. While the ability of plants to transport viral and cellular RNA molecules is consistent with RNA transport phenomena in other systems, further studies are needed to increase our ability to visualize viral RNA (vRNA) in vivo and to distinguish RNA-transport related processes from those involved in antiviral defense.
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Affiliation(s)
- Eduardo J. Peña
- Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, Université de StrasbourgStrasbourg, France
| | - Manfred Heinlein
- Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, Université de StrasbourgStrasbourg, France
- Department of Plant Physiology, University of BaselBasel, Switzerland
- *Correspondence: Manfred Heinlein, Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, UPR 2357, Université de Strasbourg, 12, Rue du Général Zimmer, 67084 Strasbourg cedex, France. e-mail:
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Link K, Vogel F, Sonnewald U. PD Trafficking of Potato Leaf Roll Virus Movement Protein in Arabidopsis Depends on Site-specific Protein Phosphorylation. FRONTIERS IN PLANT SCIENCE 2011; 2:18. [PMID: 22645527 PMCID: PMC3355765 DOI: 10.3389/fpls.2011.00018] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Accepted: 05/27/2011] [Indexed: 05/22/2023]
Abstract
Many plant viruses encode for specialized movement proteins (MP) to facilitate passage of viral material to and through plasmodesmata (PD). To analyze intracellular trafficking of potato leaf roll virus (PLRV) movement protein (MP17) we performed GFP fusion experiments with distinct deletion variants of MP17. These studies revealed that the C-terminus of MP17 is essential but not sufficient for PD targeting. Interestingly, fusion of GFP to three C-terminal MP17 deletion variants resulted in the accumulation of GFP in chloroplasts. This indicates that MP17 harbors hidden plastid targeting sequences. Previous studies showed that posttranslational protein phosphorylation influences PD targeting of MP and virus spread. Analysis of MP17-derived phospho-peptides by mass spectrometry revealed four phosphorylated serine residues (S71, S79, S137, and S140). Site-directed mutagenesis of S71/S79 and S137/S140 showed that the C-terminal serine residues S137/S140 are dispensable for PD targeting. However, exchange of S71/S79 to A71/A79 abolished PD targeting of the mutated MP17 protein. To mimic phosphorylation of S71/S79 both amino acids were substituted by aspartic acid. The resulting D71/D79 variant of MP17 was efficiently targeted to PD. Further deletion analysis showed that PD targeting of MP17 is dependent on the C-terminus, phosphorylation of S71 and/or S79 and a N-terminal domain.
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Affiliation(s)
- Katrin Link
- Lehrstuhl für Biochemie, Friedrich-Alexander Universität Erlangen-NürnbergErlangen, Germany
| | - Florian Vogel
- Lehrstuhl für Biochemie, Friedrich-Alexander Universität Erlangen-NürnbergErlangen, Germany
- Environmental Process Engineering, Friedrich-Alexander University Erlangen-Nürnberg Busan CampusBusan, Republic of Korea
| | - Uwe Sonnewald
- Lehrstuhl für Biochemie, Friedrich-Alexander Universität Erlangen-NürnbergErlangen, Germany
- *Correspondence: Uwe Sonnewald, Lehrstuhl für Biochemie, Department Biologie, Staudtstr. 5, 91058 Erlangen, Germany. e-mail:
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Tilsner J, Amari K, Torrance L. Plasmodesmata viewed as specialised membrane adhesion sites. PROTOPLASMA 2011; 248:39-60. [PMID: 20938697 DOI: 10.1007/s00709-010-0217-6] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Accepted: 09/27/2010] [Indexed: 05/20/2023]
Abstract
A significant amount of work has been expended to identify the elusive components of plasmodesmata (PD) to help understand their structure, as well as how proteins are targeted to them. This review focuses on the role that lipid membranes may play in defining PD both structurally and as subcellular targeting addresses. Parallels are drawn to findings in other areas of research which focus on the lateral segregation of membrane domains and the generation of three-dimensional organellar shapes from flat lipid bilayers. We conclude that consideration of the protein-lipid interactions in cell biological studies of PD components and PD-targeted proteins may yield new insights into some of the many open questions regarding these unique structures.
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Affiliation(s)
- Jens Tilsner
- Institute of Molecular Plant Sciences, University of Edinburgh, Mayfield Road, Edinburgh, EH9 3JH, UK.
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