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Reagan BC, Burch-Smith TM. Viruses Reveal the Secrets of Plasmodesmal Cell Biology. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:26-39. [PMID: 31715107 DOI: 10.1094/mpmi-07-19-0212-fi] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Plasmodesmata (PD) are essential for intercellular trafficking of molecules required for plant life, from small molecules like sugars and ions to macromolecules including proteins and RNA molecules that act as signals to regulate plant development and defense. As obligate intracellular pathogens, plant viruses have evolved to manipulate this communication system to facilitate the initial cell-to-cell and eventual systemic spread in their plant hosts. There has been considerable interest in how viruses manipulate the PD that connect the protoplasts of neighboring cells, and viruses have yielded invaluable tools for probing the structure and function of PD. With recent advances in biochemistry and imaging, we have gained new insights into the composition and structure of PD in the presence and absence of viruses. Here, we first discuss viral strategies for manipulating PD for their intercellular movement and examine how this has shed light on our understanding of native PD function. We then address the controversial role of the cytoskeleton in trafficking to and through PD. Finally, we address how viruses could alter PD structure and consider possible mechanisms of the phenomenon described as 'gating'. This discussion supports the significance of virus research in elucidating the properties of PD, these persistently enigmatic plant organelles.
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Affiliation(s)
- Brandon C Reagan
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, U.S.A
| | - Tessa M Burch-Smith
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, U.S.A
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2
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Navarro JA, Sanchez-Navarro JA, Pallas V. Key checkpoints in the movement of plant viruses through the host. Adv Virus Res 2019; 104:1-64. [PMID: 31439146 DOI: 10.1016/bs.aivir.2019.05.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Plant viruses cannot exploit any of the membrane fusion-based routes of entry described for animal viruses. In addition, one of the distinctive structures of plant cells, the cell wall, acts as the first barrier against the invasion of pathogens. To overcome the rigidity of the cell wall, plant viruses normally take advantage of the way of life of different biological vectors. Alternatively, the physical damage caused by environmental stresses can facilitate virus entry. Once inside the cell and taking advantage of the characteristic symplastic continuity of plant cells, viruses need to remodel and/or modify the restricted pore size of the plasmodesmata (channels that connect plant cells). In a successful interaction for the virus, it can reach the vascular tissue to systematically invade the plant. The connections between the different cell types in this path are not designed to allow the passage of molecules with the complexity of viruses. During this process, viruses face different cell barriers that must be overcome to reach the distal parts of the plant. In this review, we highlight the current knowledge about how plant RNA viruses enter plant cells, move between them to reach vascular cells and overcome the different physical and cellular barriers that the phloem imposes. Finally, we update the current research on cellular organelles as key regulator checkpoints in the long-distance movement of plant viruses.
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Affiliation(s)
- Jose A Navarro
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, Valencia, Spain
| | - Jesus A Sanchez-Navarro
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, Valencia, Spain
| | - Vicente Pallas
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, Valencia, Spain.
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Del Toro FJ, Mencía E, Aguilar E, Tenllado F, Canto T. HCPro-mediated transmission by aphids of purified virions does not require its silencing suppression function and correlates with its ability to coat cell microtubules in loss-of-function mutant studies. Virology 2018; 525:10-18. [PMID: 30212731 DOI: 10.1016/j.virol.2018.09.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 09/04/2018] [Accepted: 09/04/2018] [Indexed: 11/16/2022]
Abstract
Native and amino acid (aa) substitution mutants of HCPro from potato virus Y (PVY) were transiently expressed in Nicotiana benthamiana leaves. Properties of those HCPro variants with regard to silencing suppression activities, mediation of viral transmission by aphids, and subcellular localization dynamics, were determined. One mutant failed to suppress silencing in agropatch assays, but could efficiently mediate the transmission by aphids of purified virions. This mutant also retained the ability to translocate to microtubules (MTs) in stressed cells. By contrast, another single aa substitution mutant displayed native-like silencing suppression activity in agropatch assays, but could not mediate transmission of PVY virions by aphids, and could not relocate to MTs. Our data show that silencing suppression by HCPro is not required in the aphid-mediated transmission of purified virions. In addition, since the same single aa alteration compromised both, viral transmission and coating of MTs, those two properties could be functionally related.
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Affiliation(s)
- Francisco Javier Del Toro
- Departamento de Biología Medioambiental, Centro de Investigaciones Biológicas, CSIC, Madrid 28040, Spain.
| | - Eva Mencía
- Departamento de Biología Medioambiental, Centro de Investigaciones Biológicas, CSIC, Madrid 28040, Spain
| | - Emmanuel Aguilar
- Departamento de Biología Medioambiental, Centro de Investigaciones Biológicas, CSIC, Madrid 28040, Spain
| | - Francisco Tenllado
- Departamento de Biología Medioambiental, Centro de Investigaciones Biológicas, CSIC, Madrid 28040, Spain
| | - Tomas Canto
- Departamento de Biología Medioambiental, Centro de Investigaciones Biológicas, CSIC, Madrid 28040, Spain.
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Abstract
Microtubules (MTs) form a rapidly adaptable network of filaments that radiate throughout the cell. These dynamic arrays facilitate a wide range of cellular processes, including the capture, transport, and spatial organization of cargos and organelles, as well as changes in cell shape, polarity, and motility. Nucleating from MT-organizing centers, including but by no means limited to the centrosome, MTs undergo rapid transitions through phases of growth, pause, and catastrophe, continuously exploring and adapting to the intracellular environment. Subsets of MTs can become stabilized in response to environmental cues, acquiring distinguishing posttranslational modifications and performing discrete functions as specialized tracks for cargo trafficking. The dynamic behavior and organization of the MT array is regulated by MT-associated proteins (MAPs), which include a subset of highly specialized plus-end-tracking proteins (+TIPs) that respond to signaling cues to alter MT behavior. As pathogenic cargos, viruses require MTs to transport to and from their intracellular sites of replication. While interactions with and functions for MT motor proteins are well characterized and extensively reviewed for many viruses, this review focuses on MT filaments themselves. Changes in the spatial organization and dynamics of the MT array, mediated by virus- or host-induced changes to MT regulatory proteins, not only play a central role in the intracellular transport of virus particles but also regulate a wider range of processes critical to the outcome of infection.
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5
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Hong JS, Ju HJ. The Plant Cellular Systems for Plant Virus Movement. THE PLANT PATHOLOGY JOURNAL 2017; 33:213-228. [PMID: 28592941 PMCID: PMC5461041 DOI: 10.5423/ppj.rw.09.2016.0198] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2016] [Revised: 11/05/2016] [Accepted: 11/13/2016] [Indexed: 05/24/2023]
Abstract
Plasmodesmata (PDs) are specialized intercellular channels that facilitate the exchange of various molecules, including sugars, ribonucleoprotein complexes, transcription factors, and mRNA. Their diameters, estimated to be 2.5 nm in the neck region, are too small to transfer viruses or viral genomes. Tobacco mosaic virus and Potexviruses are the most extensively studied viruses. In viruses, the movement protein (MP) is responsible for the PD gating that allows the intercellular movement of viral genomes. Various host factors interact with MP to regulate complicated mechanisms related to PD gating. Virus replication and assembly occur in viral replication complex (VRC) with membrane association, especially in the endoplasmic reticulum. VRC have a highly organized structure and are highly regulated by interactions among the various host factors, proteins encoded by the viral genome, and the viral genome. Virus trafficking requires host machineries, such as the cytoskeleton and the secretory systems. MP facilitates the virus replication and movement process. Despite the current level of understanding of virus movement, there are still many unknown and complex interactions between virus replication and virus movement. While numerous studies have been conducted to understand plant viruses with regards to cell-to-cell movement and replication, there are still many knowledge gaps. To study these interactions, adequate research tools must be used such as molecular, and biochemical techniques. Without such tools, virologists will not be able to gain an accurate or detailed understanding of the virus infection process.
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Affiliation(s)
- Jin-Sung Hong
- Department of Applied Biology, College of Agriculture and Life Sciences, Kangwon National University, Chuncheon 24341, Korea
| | - Ho-Jong Ju
- Department of Agricultural Biology, College of Agricultural Life Science, Chonbuk National University, Jeonju 54896, Korea
- Plant Medicinal Research Center, College of Agricultural Life Science, Chonbuk National University, Jeonju 54896, Korea
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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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Peña EJ, Heinlein M. Cortical microtubule-associated ER sites: organization centers of cell polarity and communication. CURRENT OPINION IN PLANT BIOLOGY 2013; 16:764-73. [PMID: 24269577 DOI: 10.1016/j.pbi.2013.10.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 09/24/2013] [Accepted: 10/01/2013] [Indexed: 05/21/2023]
Abstract
Anisotropic cell growth and the ability of plant cells to communicate within and across the borders of cellular and supracellular domains depends on the ability of the cells to dynamically establish polarized networks able to deliver structural and informational macromolecules to distinct cellular sites. Studies of organelle movements and transport of endogenous and viral proteins suggest that organelle and macromolecular trafficking pathways involve transient or stable interactions with cortical microtubule-associated endoplasmic reticulum sites (C-MERs). The observations suggest that C-MERs may function as cortical hubs that organize cargo exchange between organelles and allow the recruitment, assembly, and subsequently site-specific delivery of macromolecular complexes. We propose that viruses interact with such hubs for replication and intercellular spread.
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Affiliation(s)
- Eduardo José Peña
- Institut de Biologie Moléculaire des Plantes, UPR 2357, Centre National de la Recherche Scientifique, Strasbourg 67084, France
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8
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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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Liu C, Nelson RS. The cell biology of Tobacco mosaic virus replication and movement. FRONTIERS IN PLANT SCIENCE 2013; 4:12. [PMID: 23403525 PMCID: PMC3568708 DOI: 10.3389/fpls.2013.00012] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 01/17/2013] [Indexed: 05/19/2023]
Abstract
Successful systemic infection of a plant by Tobacco mosaic virus (TMV) requires three processes that repeat over time: initial establishment and accumulation in invaded cells, intercellular movement, and systemic transport. Accumulation and intercellular movement of TMV necessarily involves intracellular transport by complexes containing virus and host proteins and virus RNA during a dynamic process that can be visualized. Multiple membranes appear to assist TMV accumulation, while membranes, microfilaments and microtubules appear to assist TMV movement. Here we review cell biological studies that describe TMV-membrane, -cytoskeleton, and -other host protein interactions which influence virus accumulation and movement in leaves and callus tissue. The importance of understanding the developmental phase of the infection in relationship to the observed virus-membrane or -host protein interaction is emphasized. Utilizing the latest observations of TMV-membrane and -host protein interactions within our evolving understanding of the infection ontogeny, a model for TMV accumulation and intracellular spread in a cell biological context is provided.
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Affiliation(s)
| | - Richard S. Nelson
- *Correspondence: Richard S. Nelson, Plant Biology Division, The Samuel Roberts Noble Foundation, Inc., 2510 Sam Noble Parkway, Ardmore, OK 73401, USA. e-mail:
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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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11
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Niehl A, Heinlein M. Cellular pathways for viral transport through plasmodesmata. PROTOPLASMA 2011; 248:75-99. [PMID: 21125301 DOI: 10.1007/s00709-010-0246-1] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Accepted: 11/16/2010] [Indexed: 05/03/2023]
Abstract
Plant viruses use plasmodesmata (PD) to spread infection between cells and systemically. Dependent on viral species, movement through PD can occur in virion or non-virion form, and requires different mechanisms for targeting and modification of the pore. These mechanisms are supported by viral movement proteins and by other virus-encoded factors that interact among themselves and with plant cellular components to facilitate virus movement in a coordinated and regulated fashion.
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Affiliation(s)
- Annette Niehl
- Institut de Biologie Moléculaire des Plantes du CNRS, Université de Strasbourg, 12 rue du Général Zimmer, 67084, Strasbourg, France
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12
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Harries PA, Schoelz JE, Nelson RS. Intracellular transport of viruses and their components: utilizing the cytoskeleton and membrane highways. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:1381-93. [PMID: 20653412 DOI: 10.1094/mpmi-05-10-0121] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Plant viruses are obligate organisms that require host components for movement within and between cells. A mechanistic understanding of virus movement will allow the identification of new methods to control virus systemic spread and serve as a model system for understanding host macromolecule intra- and intercellular transport. Recent studies have moved beyond the identification of virus proteins involved in virus movement and their effect on plasmodesmal size exclusion limits to the analysis of their interactions with host components to allow movement within and between cells. It is clear that individual virus proteins and replication complexes associate with and, in some cases, traffic along the host cytoskeleton and membranes. Here, we review these recent findings, highlighting the diverse associations observed between these components and their trafficking capacity. Plant viruses operate individually, sometimes within virus species, to utilize unique interactions between their proteins or complexes and individual host cytoskeletal or membrane elements over time or space for their movement. However, there is not sufficient information for any plant virus to create a complete model of its intracellular movement; thus, more research is needed to achieve that goal.
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Affiliation(s)
- Phillip A Harries
- Department of Biology, Pittsburg State University, Pittsburg, KS 66762, USA
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13
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Ouko MO, Sambade A, Brandner K, Niehl A, Peña E, Ahad A, Heinlein M, Nick P. Tobacco mutants with reduced microtubule dynamics are less susceptible to TMV. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 62:829-39. [PMID: 20230489 DOI: 10.1111/j.1365-313x.2010.04195.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
A panel of seven SR1 tobacco mutants (ATER1 to ATER7) derived via T-DNA activation tagging and screening for resistance to a microtubule assembly inhibitor, ethyl phenyl carbamate, were used to study the role of microtubules during infection and spread of tobacco mosaic virus (TMV). In one of these lines, ATER2, alpha-tubulin is shifted from the tyrosinylated into the detyrosinated form, and the microtubule plus-end marker GFP-EB1 moves significantly slower when expressed in the background of the ATER2 mutant as compared with the SR1 wild type. The efficiency of cell-to-cell movement of TMV encoding GFP-tagged movement protein (MP-GFP) is reduced in ATER2 accompanied by a reduced association of MP-GFP with plasmodesmata. This mutant is also more tolerant to viral infection as compared with the SR1 wild type, implying that reduced microtubule dynamics confer a comparative advantage in face of TMV infection.
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Affiliation(s)
- Maurice O Ouko
- Botanical Institute 1, University of Karlsruhe, Kaiserstrasse 2, D-76128 Karlsruhe, Germany
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Su S, Liu Z, Chen C, Zhang Y, Wang X, Zhu L, Miao L, Wang XC, Yuan M. Cucumber mosaic virus movement protein severs actin filaments to increase the plasmodesmal size exclusion limit in tobacco. THE PLANT CELL 2010; 22:1373-87. [PMID: 20435906 PMCID: PMC2879750 DOI: 10.1105/tpc.108.064212] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 03/27/2010] [Accepted: 04/08/2010] [Indexed: 05/19/2023]
Abstract
Plant viral movement proteins (MPs) enable viruses to pass through cell walls by increasing the size exclusion limit (SEL) of plasmodesmata (PD). Here, we report that the ability of Cucumber mosaic virus (CMV) MP to increase the SEL of the PD could be inhibited by treatment with the actin filament (F-actin)-stabilizing agent phalloidin but not by treatment with the F-actin-destabilizing agent latrunculin A. In vitro studies showed that CMV MP bound globular and F-actin, inhibited actin polymerization, severed F-actin, and participated in plus end capping of F-actin. Analyses of two CMV MP mutants, one with and one without F-actin severing activities, demonstrated that the F-actin severing ability was required to increase the PD SEL. Furthermore, the Tobacco mosaic virus MP also exhibited F-actin severing activity, and its ability to increase the PD SEL was inhibited by treatment with phalloidin. Our data provide evidence to support the hypothesis that F-actin severing is required for MP-induced increase in the SEL of PD. This may have broad implications in the study of the mechanisms of actin dynamics that regulate cell-to-cell transport of viral and endogenous proteins.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Ming Yuan
- State Key Laboratory of Plant Physiology and Biochemistry, Department of Plant Sciences, College of Biological Sciences, China Agricultural University, Beijing 100193, China
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Sambade A, Heinlein M. Approaching the cellular mechanism that supports the intercellular spread of Tobacco mosaic virus. PLANT SIGNALING & BEHAVIOR 2009; 4:35-8. [PMID: 19704702 PMCID: PMC2634067 DOI: 10.4161/psb.4.1.7253] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2008] [Accepted: 10/23/2008] [Indexed: 05/20/2023]
Abstract
Plant viruses spread cell-to-cell in infected plants by exploiting plasmodesmata (PD), gatable channels in the cell wall that provide cytoplasmic passageways for the trafficking of informational macromolecules. Since it became known that the intercellular spread of Tobacco mosaic virus (TMV) depends on virus-encoded movement protein (MP), the mechanism by which this protein mediates in the targeting of this virus to PD is subject to intense studies. TMV movement occurs in a non-encapsidated form and thus promises to reveal important host functions involved in the intra-and intercellular trafficking of RNA molecules. We have recently presented new evidence that the cell-to-cell trafficking of TMV RNA (vRNA) involves the formation and intracellular trafficking of distinct MP particles. Upon assembly, these particles detach from cortical microtubule (MT) sites and then move with the flow of ER through the cell. During passage the particles continue to undergo transient interactions with MT which may guide the particles to their destination. The comprehensive analysis of particle composition may lead to important insights into the regulation of RNA transport in plants and may also reveal potential similarities to RNA transport mechanisms in animals and humans.
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Affiliation(s)
- Adrian Sambade
- Institut de Biologie Moléculaire des Plantes, Laboratoire propre du CNRS (UPR 2357) conventionné avec l'Université Louis Pasteur (Strasbourg 1), Strasbourg, France
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Sambade A, Brandner K, Hofmann C, Seemanpillai M, Mutterer J, Heinlein M. Transport of TMV movement protein particles associated with the targeting of RNA to plasmodesmata. Traffic 2008; 9:2073-88. [PMID: 19281527 DOI: 10.1111/j.1600-0854.2008.00824.x] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The cell-to-cell movement of Tobacco mosaic virus through plasmodesmata (PD) requires virus-encoded movement protein (MP). The MP targets PD through the endoplasmic reticulum (ER)/actin network, whereas the intercellular movement of the viral RNA genome has been correlated with the association of the MP with mobile, microtubule-proximal particles in cells at the leading front of infection as well as the accumulation of the protein on the microtubule network during later infection stages. To understand how the associations of MP with ER and microtubules are functionally connected, we applied multiple marker three-dimensional confocal and time-lapse video microscopies to Nicotiana benthamiana cells expressing fluorescent MP, fluorescent RNA and fluorescent cellular markers. We report the reconstitution of MP-dependent RNA transport to PD in a transient assay. We show that transiently expressed MP occurs in association with small particles as observed during infection. The same MP accumulates in PD and mediates the transport of its messenger RNA transcript to the pore. In the cellular cortex, the particles occur at microtubule-proximal sites and can undergo ER-associated and latrunculin-sensitive movements between such sites. These and other observations suggest that the microtubule network performs anchorage and release functions for controlling the assembly and intracellular movement of MP-containing RNA transport particles in association with the ER.
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Affiliation(s)
- Adrian Sambade
- Department of Integrative Virology, Institut de Biologie Moléculaire des Plantes, laboratoire propre du CNRS (UPR 2357) conventionné avec l'Université Louis Pasteur (Strasbourg 1), 12 rue du Général Zimmer, 67084 Strasbourg CEDEX, France
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Brandner K, Sambade A, Boutant E, Didier P, Mély Y, Ritzenthaler C, Heinlein M. Tobacco mosaic virus movement protein interacts with green fluorescent protein-tagged microtubule end-binding protein 1. PLANT PHYSIOLOGY 2008; 147:611-23. [PMID: 18408045 PMCID: PMC2409024 DOI: 10.1104/pp.108.117481] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Accepted: 04/01/2008] [Indexed: 05/19/2023]
Abstract
The targeting of the movement protein (MP) of Tobacco mosaic virus to plasmodesmata involves the actin/endoplasmic reticulum network and does not require an intact microtubule cytoskeleton. Nevertheless, the ability of MP to facilitate the cell-to-cell spread of infection is tightly correlated with interactions of the protein with microtubules, indicating that the microtubule system is involved in the transport of viral RNA. While the MP acts like a microtubule-associated protein able to stabilize microtubules during late infection stages, the protein was also shown to cause the inactivation of the centrosome upon expression in mammalian cells, thus suggesting that MP may interact with factors involved in microtubule attachment, nucleation, or polymerization. To further investigate the interactions of MP with the microtubule system in planta, we expressed the MP in the presence of green fluorescent protein (GFP)-fused microtubule end-binding protein 1a (EB1a) of Arabidopsis (Arabidopsis thaliana; AtEB1a:GFP). The two proteins colocalize and interact in vivo as well as in vitro and exhibit mutual functional interference. These findings suggest that MP interacts with EB1 and that this interaction may play a role in the associations of MP with the microtubule system during infection.
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Affiliation(s)
- Katrin Brandner
- Institut de Biologie Moléculaire des Plantes, laboratoire propre du CNRS (UPR 2357) conventionné avec l'Université Louis Pasteur, 67084 Strasbourg cedex, France
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Schepetilnikov MV, Solovyev AG, Gorshkova EN, Schiemann J, Prokhnevsky AI, Dolja VV, Morozov SY. Intracellular targeting of a hordeiviral membrane-spanning movement protein: sequence requirements and involvement of an unconventional mechanism. J Virol 2008; 82:1284-93. [PMID: 18032484 PMCID: PMC2224415 DOI: 10.1128/jvi.01164-07] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2007] [Accepted: 11/12/2007] [Indexed: 12/14/2022] Open
Abstract
The membrane-spanning protein TGBp3 is one of the three movement proteins (MPs) of Poa semilatent virus. TGBp3 is thought to direct other viral MPs and genomic RNA to peripheral bodies located in close proximity to plasmodesmata. We used the ectopic expression of green fluorescent protein-fused TGBp3 in epidermal cells of Nicotiana benthamiana leaves to study the TGBp3 intracellular trafficking pathway. Treatment with inhibitors was used to reveal that the targeting of TGBp3 to plasmodesmata does not require a functional cytoskeleton or secretory system. In addition, the suppression of endoplasmic reticulum-derived vesicle formation by a dominant negative mutant of small GTPase Sar1 had no detectable effect on TGBp3 trafficking to peripheral bodies. Collectively, these results suggested the involvement of an unconventional pathway in the intracellular transport of TGBp3. The determinants of targeting to plasmodesmata were localized to the C-terminal region of TGBp3, including the conserved hydrophilic and terminal membrane-spanning domains.
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Affiliation(s)
- Mikhail V Schepetilnikov
- Department of Botany and Plant Pathology, Oregon State University, Cordley Hall 2082, Corvallis, OR 97331, USA
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Boyko V, Hu Q, Seemanpillai M, Ashby J, Heinlein M. Validation of microtubule-associated Tobacco mosaic virus RNA movement and involvement of microtubule-aligned particle trafficking. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2007; 51:589-603. [PMID: 17584190 DOI: 10.1111/j.1365-313x.2007.03163.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Functional studies of Tobacco mosaic virus (TMV) infection using virus derivatives expressing functional, dysfunctional, and temperature-sensitive movement protein (MP) mutants indicated that the cell-to-cell transport of TMV RNA is functionally correlated with the association of MP with microtubules. However, the role of microtubules in the movement process during early infection remains unclear, since MP accumulates on microtubules rather late in infection and treatment of plants with microtubule-disrupting agents fails to strongly interfere with cell-to-cell movement of TMV RNA. To further test the role of microtubules in TMV cell-to-cell movement, we investigated TMV strain Ni2519, which is temperature-sensitive for movement. We demonstrate that the temperature-sensitive defect in movement is correlated with temperature-sensitive changes in the localization of MP to microtubules. Furthermore, we show that during early phases of recovery from non-permissive conditions, the MP localizes to microtubule-associated particles. Similar particles are found in cells at the leading front of spreading TMV infection sites. Initially mobile, the particles become immobile when MP starts to accumulate along the length of the particle-associated microtubules. Our observations confirm a role for microtubules in the spread of TMV infection and associate this role with microtubule-associated trafficking of MP-containing particles in cells engaged in the cell-to-cell movement of the TMV genome.
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Affiliation(s)
- Vitaly Boyko
- Friedrich Miescher Institute for Biomedical Research, PO Box 2543, CH-4002 Basel, Switzerland
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Hofmann C, Sambade A, Heinlein M. Plasmodesmata and intercellular transport of viral RNA. Biochem Soc Trans 2007; 35:142-5. [PMID: 17233621 DOI: 10.1042/bst0350142] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cell-to-cell communication in plants involves the symplastic trafficking of informational protein and RNA macromolecules through cytoplasmic bridges in the plant cell wall known as plasmodesmata. Viruses exploit this route for the spread of infection and are used as a model to study the mechanisms by which macromolecules are targeted to the pore. Studies using tobacco mosaic virus have led to the identification of host components that participate in plasmodesmal targeting of viral RNA and movement protein.
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Affiliation(s)
- C Hofmann
- Institut de Biologie Moléculaire des Plantes, Laboratoire propre du CNRS (Centre National de la Recherche Scientifique) (UPR 2357) conventionné avec l'Université Louis Pasteur (Strasbourg 1), 12 rue du Général Zimmer, 67084 Strasbourg Cedex, France
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Curin M, Ojangu EL, Trutnyeva K, Ilau B, Truve E, Waigmann E. MPB2C, a microtubule-associated plant factor, is required for microtubular accumulation of tobacco mosaic virus movement protein in plants. PLANT PHYSIOLOGY 2007; 143:801-11. [PMID: 17189338 PMCID: PMC1803734 DOI: 10.1104/pp.106.091488] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2006] [Accepted: 11/22/2006] [Indexed: 05/13/2023]
Abstract
Movement protein binding 2C (MPB2C) is a plant endogenous microtubule-associated protein previously identified as an interaction partner of tobacco (Nicotiana tabacum) mosaic virus movement protein (TMV-MP). In this work, the role of MPB2C in cell-to-cell transport of TMV-MP, viral spread of TMV, and subcellular localization of TMV-MP was examined. To this end, plants with reduced MPB2C levels were generated by a gene-silencing strategy. Local and systemic spread of TMV and cell-to-cell movement of TMV-MP were unimpaired in MPB2C-silenced plants as compared to nonsilenced plants, indicating that MPB2C is not required for intercellular transport of TMV-MP itself or spread of TMV. However, a clear change in subcellular distribution of TMV-MP characterized by a nearly complete loss of microtubular localization was observed in MPB2C-silenced plants. This result shows that the MPB2C is a central player in determining the complex subcellular localization of TMV-MP, in particular its microtubular accumulation, a phenomenon that has been frequently observed and whose role is still under discussion. Clearly, MPB2C mediated accumulation of TMV-MP at microtubules is not required for intercellular spread but may be a means to withdraw the TMV-MP from the cell-to-cell transport pathway.
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Affiliation(s)
- Mirela Curin
- Max F. Perutz Laboratories, University Departments at the Vienna Biocenter, Department of Medical Biochemistry, Medical University of Vienna, A-1030 Vienna, Austria
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Wright KM, Wood NT, Roberts AG, Chapman S, Boevink P, Mackenzie KM, Oparka KJ. Targeting of TMV movement protein to plasmodesmata requires the actin/ER network: evidence from FRAP. Traffic 2007; 8:21-31. [PMID: 17132144 DOI: 10.1111/j.1600-0854.2006.00510.x] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Fluorescence recovery after photobleaching (FRAP) was used to study the mechanism by which fluorescent-protein-tagged movement protein (MP) of tobacco mosaic virus (TMV) is targeted to plasmodesmata (PD). The data show that fluorescence recovery in PD at the leading edge of an infection requires elements of the cortical actin/endoplasmic reticulum (ER) network and can occur in the absence of an intact microtubule (MT) cytoskeleton. Inhibitors of the actin cytoskeleton (latrunculin and cytochalasin) significantly inhibited MP targeting, while MT inhibitors (colchicine and oryzalin) did not. Application of sodium azide to infected cells implicated an active component of MP transfer to PD. Treatment of cells with Brefeldin A (BFA) at a concentration that caused reabsorption of the Golgi bodies into the ER (precluding secretion of viral MP) had no effect on MP targeting, while disruption of the cortical ER with higher concentrations of BFA caused significant inhibition. Our results support a model of TMV MP function in which targeting of MP to PD during infection is mediated by the actin/ER network.
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Affiliation(s)
- Kathryn M Wright
- Programme of Plant Pathology, Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK.
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Ashby J, Boutant E, Seemanpillai M, Groner A, Sambade A, Ritzenthaler C, Heinlein M. Tobacco mosaic virus movement protein functions as a structural microtubule-associated protein. J Virol 2006; 80:8329-44. [PMID: 16912284 PMCID: PMC1563862 DOI: 10.1128/jvi.00540-06] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2006] [Accepted: 06/04/2006] [Indexed: 12/24/2022] Open
Abstract
The cell-to-cell spread of Tobacco mosaic virus infection depends on virus-encoded movement protein (MP), which is believed to form a ribonucleoprotein complex with viral RNA (vRNA) and to participate in the intercellular spread of infectious particles through plasmodesmata. Previous studies in our laboratory have provided evidence that the vRNA movement process is correlated with the ability of the MP to interact with microtubules, although the exact role of this interaction during infection is not known. Here, we have used a variety of in vivo and in vitro assays to determine that the MP functions as a genuine microtubule-associated protein that binds microtubules directly and modulates microtubule stability. We demonstrate that, unlike MP in whole-cell extract, microtubule-associated MP is not ubiquitinated, which strongly argues against the hypothesis that microtubules target the MP for degradation. In addition, we found that MP interferes with kinesin motor activity in vitro, suggesting that microtubule-associated MP may interfere with kinesin-driven transport processes during infection.
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Affiliation(s)
- Jamie Ashby
- Institut de Biologie Moléculaire des Plantes, Strasbourg, France
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