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Movahed N, Patarroyo C, Sun J, Vali H, Laliberté JF, Zheng H. Cylindrical Inclusion Protein of Turnip Mosaic Virus Serves as a Docking Point for the Intercellular Movement of Viral Replication Vesicles. PLANT PHYSIOLOGY 2017; 175:1732-1744. [PMID: 29089395 PMCID: PMC5717746 DOI: 10.1104/pp.17.01484] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 10/27/2017] [Indexed: 05/22/2023]
Abstract
Plant viruses move from the initially infected cell to adjacent cells through plasmodesmata (PDs). To do so, viruses encode dedicated protein(s) that facilitate this process. How viral proteins act together to support the intercellular movement of viruses is poorly defined. Here, by using an infection-free intercellular vesicle movement assay, we investigate the action of CI (cylindrical inclusion) and P3N-PIPO (amino-terminal half of P3 fused to Pretty Interesting Potyviridae open reading frame), the two PD-localized potyviral proteins encoded by Turnip mosaic virus (TuMV), in the intercellular movement of the viral replication vesicles. We provide evidence that CI and P3N-PIPO are sufficient to support the PD targeting and intercellular movement of TuMV replication vesicles induced by 6K2, a viral protein responsible for the generation of replication vesicles. 6K2 interacts with CI but not P3N-PIPO. When this interaction is impaired, the intercellular movement of TuMV replication vesicles is inhibited. Furthermore, in transmission electron microscopy, vesicular structures are observed in connection with the cylindrical inclusion bodies at structurally modified PDs in cells coexpressing 6K2, CI, and P3N-PIPO. CI is directed to PDs through its interaction with P3N-PIPO. We hypothesize that CI serves as a docking point for PD targeting and the intercellular movement of TuMV replication vesicles. This work contributes to a better understanding of the roles of different viral proteins in coordinating the intercellular movement of viral replication vesicles.
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Affiliation(s)
- Nooshin Movahed
- Department of Biology, McGill University, Montreal, Quebec H3B 1A1, Canada
| | - Camilo Patarroyo
- Department of Biology, McGill University, Montreal, Quebec H3B 1A1, Canada
| | - Jiaqi Sun
- Department of Biology, McGill University, Montreal, Quebec H3B 1A1, Canada
| | - Hojatollah Vali
- Facility for Electron Microscopy Research, McGill University, Montreal, Quebec H3A 0C7, Canada
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec H3A 0C7, Canada
| | | | - Huanquan Zheng
- Department of Biology, McGill University, Montreal, Quebec H3B 1A1, Canada
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Solovyev AG, Morozov SY. Non-replicative Integral Membrane Proteins Encoded by Plant Alpha-Like Viruses: Emergence of Diverse Orphan ORFs and Movement Protein Genes. FRONTIERS IN PLANT SCIENCE 2017; 8:1820. [PMID: 29163564 PMCID: PMC5663686 DOI: 10.3389/fpls.2017.01820] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Accepted: 10/06/2017] [Indexed: 06/07/2023]
Abstract
Fast accumulation of sequencing data on plant virus genomes and plant transcriptomes demands periodic re-evaluation of current views on the genome evolution of viruses. Here, we substantiate and further detail our previously mostly speculative model on the origin and evolution of triple gene block (TGB) encoding plant virus movement proteins TGB1, TGB2, and TGB3. Recent experimental data on functional competence of transport gene modules consisting of two proteins related to TGB1 and TGB2, as well as sequence analysis data on similarity of TGB2 and TGB3 encoded by a viral genome and virus-like RNAs identified in a plant transcriptomes, suggest that TGB evolution involved events of gene duplication and gene transfer between viruses. In addition, our analysis identified that plant RNA-seq data assembled into RNA virus-like contigs encode a significant variety of hydrophobic proteins. Functions of these orphan proteins are still obscure; however, some of them are obviously related to hydrophobic virion proteins of recently sequenced invertebrate (mostly insect) viruses, therefore supporting the current view on a common origin for many groups of plant and insect RNA-containing viruses. Moreover, these findings may suggest that the function of at least some orphan hydrophobic proteins is to provide plant viruses with the ability to infect insect hosts. In general, our observations emphasize that comparison of RNA virus sequences in a large variety of land plants and algae isolated geographically and ecologically may lead to experimental confirmation of previously purely speculative schemes of evolution of single genes, gene modules, and whole genomes.
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Affiliation(s)
- Andrey G. Solovyev
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia
- Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow, Russia
| | - Sergey Y. Morozov
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia
- Department of Virology, Biological Faculty, Moscow State University, Moscow, Russia
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Qiao W, Medina V, Falk BW. Inspirations on Virus Replication and Cell-to-Cell Movement from Studies Examining the Cytopathology Induced by Lettuce infectious yellows virus in Plant Cells. FRONTIERS IN PLANT SCIENCE 2017; 8:1672. [PMID: 29021801 PMCID: PMC5623981 DOI: 10.3389/fpls.2017.01672] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 09/12/2017] [Indexed: 05/06/2023]
Abstract
Lettuce infectious yellows virus (LIYV) is the type member of the genus Crinivirus in the family Closteroviridae. Like many other positive-strand RNA viruses, LIYV infections induce a number of cytopathic changes in plant cells, of which the two most characteristic are: Beet yellows virus-type inclusion bodies composed of vesicles derived from cytoplasmic membranes; and conical plasmalemma deposits (PLDs) located at the plasmalemma over plasmodesmata pit fields. The former are not only found in various closterovirus infections, but similar structures are known as 'viral factories' or viroplasms in cells infected with diverse types of animal and plant viruses. These are generally sites of virus replication, virion assembly and in some cases are involved in cell-to-cell transport. By contrast, PLDs induced by the LIYV-encoded P26 non-virion protein are not involved in replication but are speculated to have roles in virus intercellular movement. These deposits often harbor LIYV virions arranged to be perpendicular to the plasma membrane over plasmodesmata, and our recent studies show that P26 is required for LIYV systemic plant infection. The functional mechanism of how LIYV P26 facilitates intercellular movement remains unclear, however, research on other plant viruses provides some insights on the possible ways of viral intercellular movement through targeting and modifying plasmodesmata via interactions between plant cellular components and viral-encoded factors. In summary, beginning with LIYV, we review the studies that have uncovered the biological determinants giving rise to these cytopathological effects and their importance in viral replication, virion assembly and intercellular movement during the plant infection by closteroviruses, and compare these findings with those for other positive-strand RNA viruses.
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Affiliation(s)
- Wenjie Qiao
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States
| | - Vicente Medina
- Department of Crop and Forest Sciences, University of Lleida, Lleida, Spain
| | - Bryce W. Falk
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States
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Cheng G, Dong M, Xu Q, Peng L, Yang Z, Wei T, Xu J. Dissecting the Molecular Mechanism of the Subcellular Localization and Cell-to-cell Movement of the Sugarcane mosaic virus P3N-PIPO. Sci Rep 2017; 7:9868. [PMID: 28852157 PMCID: PMC5575073 DOI: 10.1038/s41598-017-10497-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 08/09/2017] [Indexed: 02/02/2023] Open
Abstract
The coding sequence of P3N-PIPO was cloned by fusion PCR from Sugarcane mosaic virus (SCMV), a main causal agent of sugarcane (Saccharum spp. hybrid) mosaic disease. SCMV P3N-PIPO preferentially localized to the plasma membrane (PM) compared with the plasmodesmata (PD), as demonstrated by transient expression and plasmolysis assays in the leaf epidermal cells of Nicotiana benthamiana. The subcellular localization of the P3N-PIPO mutants P3N-PIPOT1 and P3N-PIPOT2 with 29 and 63 amino acids deleted from the C-terminus of PIPO, respectively, revealed that the 19 amino acids at the N-terminus of PIPO contributed to the PD localization. Interaction assays showed that the 63 amino acids at the C-terminus of PIPO determined the P3N-PIPO interaction with PM-associated Ca2+-binding protein 1, ScPCaP1, which was isolated from the SCMV-susceptible sugarcane cultivar Badila. Like wild-type P3N-PIPO, P3N-PIPOT1 and P3N-PIPOT2 could translocate to neighbouring cells and recruit the SCMV cylindrical inclusion protein to the PM. Thus, interactions with ScPCaP1 may contribute to, but not determine, SCMV Pm3N-PIPO’s localization to the PM or PD. These results also imply the existence of truncated P3N-PIPO in nature.
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Affiliation(s)
- Guangyuan Cheng
- Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Meng Dong
- Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Qian Xu
- Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Lei Peng
- Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Zongtao Yang
- Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Taiyun Wei
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China.
| | - Jingsheng Xu
- Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China.
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Bruckner FP, Xavier ADS, Cascardo RDS, Otoni WC, Zerbini FM, Alfenas‐Zerbini P. Translationally controlled tumour protein (TCTP) from tomato and Nicotiana benthamiana is necessary for successful infection by a potyvirus. MOLECULAR PLANT PATHOLOGY 2017; 18:672-683. [PMID: 27159273 PMCID: PMC6638207 DOI: 10.1111/mpp.12426] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 05/02/2016] [Accepted: 05/05/2016] [Indexed: 05/20/2023]
Abstract
Translationally controlled tumour protein (TCTP) is a ubiquitously distributed protein in eukaryotes, involved in the regulation of several processes, including cell cycle progression, cell growth, stress protection, apoptosis and maintenance of genomic integrity. Its expression is induced during the early stages of tomato (Solanum lycopersicum) infection by the potyvirus Pepper yellow mosaic virus (PepYMV, a close relative of Potato virus Y). Tomato TCTP is a protein of 168 amino acids, which contains all the conserved domains of the TCTP family. To study the effects of TCTP silencing in PepYMV infection, Nicotiana benthamiana plants were silenced by virus-induced gene silencing (VIGS) and transgenic tomato plants silenced for TCTP were obtained. In the early stages of infection, both tomato and N. benthamiana silenced plants accumulated less virus than control plants. Transgenic tomato plants showed a drastic reduction in symptoms and no viral accumulation at 14 days post-inoculation. Subcellular localization of TCTP was determined in healthy and systemically infected N. benthamiana leaves. TCTP was observed in both the nuclei and cytoplasm of non-infected cells, but only in the cytoplasm of infected cells. Our results indicate that TCTP is a growth regulator necessary for successful PepYMV infection and that its localization is altered by the virus, probably to favour the establishment of virus infection. A network with putative interactions that may occur between TCTP and Arabidopsis thaliana proteins was built. This network brings together experimental data of interactions that occur in other eukaryotes and helps us to discuss the possibilities of TCTP involvement in viral infection.
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Affiliation(s)
- Fernanda Prieto Bruckner
- Departamento de Microbiologia/BIOAGRO/National Institute of Science and Technology in Plant‐Pest InteractionsUniversidade Federal de ViçosaViçosaMG36570‐900Brazil
| | - André Da Silva Xavier
- Departamento de Fitopatologia/BIOAGRO/National Institute of Science and Technology in Plant‐Pest InteractionsUniversidade Federal de ViçosaViçosaMG36570‐900Brazil
| | - Renan De Souza Cascardo
- Departamento de Microbiologia/BIOAGRO/National Institute of Science and Technology in Plant‐Pest InteractionsUniversidade Federal de ViçosaViçosaMG36570‐900Brazil
| | - Wagner Campos Otoni
- Departamento de Biologia Vegetal/BIOAGROUniversidade Federal de ViçosaViçosaMG36570‐900Brazil
| | - Francisco Murilo Zerbini
- Departamento de Fitopatologia/BIOAGRO/National Institute of Science and Technology in Plant‐Pest InteractionsUniversidade Federal de ViçosaViçosaMG36570‐900Brazil
| | - Poliane Alfenas‐Zerbini
- Departamento de Microbiologia/BIOAGRO/National Institute of Science and Technology in Plant‐Pest InteractionsUniversidade Federal de ViçosaViçosaMG36570‐900Brazil
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56
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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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57
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Lazareva EA, Lezzhov AA, Komarova TV, Morozov SY, Heinlein M, Solovyev AG. A novel block of plant virus movement genes. MOLECULAR PLANT PATHOLOGY 2017; 18:611-624. [PMID: 27118327 PMCID: PMC6638293 DOI: 10.1111/mpp.12418] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Revised: 04/14/2016] [Accepted: 04/21/2016] [Indexed: 05/10/2023]
Abstract
Hibiscus green spot virus (HGSV) is a recently discovered and so far poorly characterized bacilliform plant virus with a positive-stranded RNA genome consisting of three RNA species. Here, we demonstrate that the proteins encoded by the ORF2 and ORF3 in HGSV RNA2 are necessary and sufficient to mediate cell-to-cell movement of transport-deficient Potato virus X in Nicotiana benthamiana. These two genes represent a specialized transport module called a 'binary movement block' (BMB), and ORF2 and ORF3 are termed BMB1 and BMB2 genes. In agroinfiltrated epidermal cells of N. benthamiana, green fluorescent protein (GFP)-BMB1 fusion protein was distributed diffusely in the cytoplasm and the nucleus. However, in the presence of BMB2, GFP-BMB1 was directed to cell wall-adjacent elongated bodies at the cell periphery, to cell wall-embedded punctate structures co-localizing with callose deposits at plasmodesmata, and to cells adjacent to the initially transformed cell. Thus, BMB2 can mediate the transport of BMB1 to and through plasmodesmata. In general, our observations support the idea that cell-to-cell trafficking of movement proteins involves an initial delivery to membrane compartments adjacent to plasmodesmata, subsequent entry of the plasmodesmata cavity and, finally, transport to adjacent cells. This process, as an alternative to tubule-based transport, has most likely evolved independently in triple gene block (TGB), double gene block (DGB), BMB and the single gene-coded transport system.
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Affiliation(s)
| | - Alexander A. Lezzhov
- Department of Virology, Biological FacultyMoscow State UniversityMoscow119234Russia
| | - Tatiana V. Komarova
- A. N. Belozersky Institute of Physico‐Chemical Biology, Moscow State UniversityMoscow119992Russia
- N. I. Vavilov Institute of General Genetics, Russian Academy of ScienceMoscow119991Russia
| | - Sergey Y. Morozov
- Department of Virology, Biological FacultyMoscow State UniversityMoscow119234Russia
- A. N. Belozersky Institute of Physico‐Chemical Biology, Moscow State UniversityMoscow119992Russia
| | - Manfred Heinlein
- Centre National de la Recherche ScientifiqueInstitut de Biologie Moléculaire des Plantes (IBMP)Strasbourg67084France
| | - Andrey G. Solovyev
- A. N. Belozersky Institute of Physico‐Chemical Biology, Moscow State UniversityMoscow119992Russia
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58
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Navarro JA, Pallás V. An Update on the Intracellular and Intercellular Trafficking of Carmoviruses. FRONTIERS IN PLANT SCIENCE 2017; 8:1801. [PMID: 29093729 PMCID: PMC5651262 DOI: 10.3389/fpls.2017.01801] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 10/04/2017] [Indexed: 05/03/2023]
Abstract
Despite harboring the smallest genomes among plant RNA viruses, carmoviruses have emerged as an ideal model system for studying essential steps of the viral cycle including intracellular and intercellular trafficking. Two small movement proteins, formerly known as double gene block proteins (DGBp1 and DGBp2), have been involved in the movement throughout the plant of some members of carmovirus genera. DGBp1 RNA-binding capability was indispensable for cell-to-cell movement indicating that viral genomes must interact with DGBp1 to be transported. Further investigation on Melon necrotic spot virus (MNSV) DGBp1 subcellular localization and dynamics also supported this idea as this protein showed an actin-dependent movement along microfilaments and accumulated at the cellular periphery. Regarding DGBp2, subcellular localization studies showed that MNSV and Pelargonium flower break virus DGBp2s were inserted into the endoplasmic reticulum (ER) membrane but only MNSV DGBp2 trafficked to plasmodesmata (PD) via the Golgi apparatus through a COPII-dependent pathway. DGBp2 function is still unknown but its localization at PD was a requisite for an efficient cell-to-cell movement. It is also known that MNSV infection can induce a dramatic reorganization of mitochondria resulting in anomalous organelles containing viral RNAs. These putative viral factories were frequently found associated with the ER near the PD leading to the possibility that MNSV movement and replication could be spatially linked. Here, we update the current knowledge of the plant endomembrane system involvement in carmovirus intra- and intercellular movement and the tentative model proposed for MNSV transport within plant cells.
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Fernández de Castro I, Tenorio R, Risco C. Virus assembly factories in a lipid world. Curr Opin Virol 2016; 18:20-6. [PMID: 26985879 DOI: 10.1016/j.coviro.2016.02.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 02/11/2016] [Accepted: 02/19/2016] [Indexed: 12/15/2022]
Abstract
Many viruses build specialized structures known as viral factories, a protected environment in which viral genome replication and morphogenesis take place. Recent findings show that viruses manipulate lipid flows to assemble these replication platforms. Viruses are thus able to create new membranes by interfering with lipid metabolism, targeting and transport; they make use of specific lipid transfer proteins (LTP) at membrane contact sites, and frequently recruit endoplasmic reticulum (ER), ER export sites, and mitochondria. Some factories, such as those built by plant and certain animal viruses, are motile membranous structures involved in intracellular or intercellular transport of the replicated viral genome. The identification of lipids and LTP subverted by viruses might lead to better understand and fight viral infections.
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Affiliation(s)
- Isabel Fernández de Castro
- Cell Structure Laboratory, Centro Nacional de Biotecnología, CNB-CSIC, UAM, Campus de Cantoblanco, 28049 Madrid, Spain.
| | - Raquel Tenorio
- Cell Structure Laboratory, Centro Nacional de Biotecnología, CNB-CSIC, UAM, Campus de Cantoblanco, 28049 Madrid, Spain
| | - Cristina Risco
- Cell Structure Laboratory, Centro Nacional de Biotecnología, CNB-CSIC, UAM, Campus de Cantoblanco, 28049 Madrid, Spain.
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60
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Verchot J. How does the stressed out ER find relief during virus infection? Curr Opin Virol 2016; 17:74-79. [PMID: 26871502 DOI: 10.1016/j.coviro.2016.01.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 01/22/2016] [Accepted: 01/25/2016] [Indexed: 01/09/2023]
Abstract
The endoplasmic reticulum and Golgi network (ERGN) is vital to most cellular biosynthetic processes. Many positive strand RNA viruses depend upon the ERGN for replication, maturation, and egress. Viruses induce changes in ER architecture and stimulate fatty acid synthesis to create environments that can scaffold replication complexes, plant virus movement complexes, or virion maturation. Potato virus X (PVX) and Turnip mosaic virus (TuMV) each encode small membrane binding proteins that embed in the ERGN and activate the unfolded protein response (UPR). The UPR ensures ERGN homeostasis in the face of environmental assaults that could negatively impact the biosynthetic functions of the ERGN. This article explores the relationship between ER stress, the UPR, and membrane synthesis occurring during virus infection.
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Affiliation(s)
- Jeanmarie Verchot
- Oklahoma State University, Department of Entomology and Plant Pathology, 127 Noble Research Center, Stillwater, OK 74078, United States.
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61
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Wan J, Basu K, Mui J, Vali H, Zheng H, Laliberté JF. Ultrastructural Characterization of Turnip Mosaic Virus-Induced Cellular Rearrangements Reveals Membrane-Bound Viral Particles Accumulating in Vacuoles. J Virol 2015; 89:12441-56. [PMID: 26423955 PMCID: PMC4665257 DOI: 10.1128/jvi.02138-15] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 09/26/2015] [Indexed: 01/02/2023] Open
Abstract
UNLABELLED Positive-strand RNA [(+) RNA] viruses remodel cellular membranes to facilitate virus replication and assembly. In the case of turnip mosaic virus (TuMV), the viral membrane protein 6K2 plays an essential role in endomembrane alterations. Although 6K2-induced membrane dynamics have been widely studied by confocal microscopy, the ultrastructure of this remodeling has not been extensively examined. In this study, we investigated the formation of TuMV-induced membrane changes by chemical fixation and high-pressure freezing/freeze substitution (HPF/FS) for transmission electron microscopy at different times of infection. We observed the formation of convoluted membranes connected to rough endoplasmic reticulum (rER) early in the infection process, followed by the production of single-membrane vesicle-like (SMVL) structures at the midstage of infection. Both SMVL and double-membrane vesicle-like structures with electron-dense cores, as well as electron-dense bodies, were found late in the infection process. Immunogold labeling results showed that the vesicle-like structures were 6K2 tagged and suggested that only the SMVL structures were viral RNA replication sites. Electron tomography (ET) was used to regenerate a three-dimensional model of these vesicle-like structures, which showed that they were, in fact, tubules. Late in infection, we observed filamentous particle bundles associated with electron-dense bodies, which suggests that these are sites for viral particle assembly. In addition, TuMV particles were observed to accumulate in the central vacuole as membrane-associated linear arrays. Our work thus unravels the sequential appearance of distinct TuMV-induced membrane structures for viral RNA replication, viral particle assembly, and accumulation. IMPORTANCE Positive-strand RNA viruses remodel cellular membranes for different stages of the infection process, such as protein translation and processing, viral RNA synthesis, particle assembly, and virus transmission. The ultrastructure of turnip mosaic virus (TuMV)-induced membrane remodeling was investigated over several days of infection. The first change that was observed involved endoplasmic reticulum-connected convoluted membrane accumulation. This was followed by the formation of single-membrane tubules, which were shown to be viral RNA replication sites. Later in the infection process, double-membrane tubular structures were observed and were associated with viral particle bundles. In addition, TuMV particles were observed to accumulate in the central vacuole as membrane-associated linear arrays. This work thus unravels the sequential appearance of distinct TuMV-induced membrane structures for viral RNA replication, viral particle assembly, and accumulation.
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Affiliation(s)
- Juan Wan
- INRS-Institut Armand-Frappier, Laval, Québec, Canada
| | - Kaustuv Basu
- Facility for Electron Microscopy Research, McGill University, Montréal, Québec, Canada
| | - Jeannie Mui
- Facility for Electron Microscopy Research, McGill University, Montréal, Québec, Canada
| | - Hojatollah Vali
- Facility for Electron Microscopy Research, McGill University, Montréal, Québec, Canada Department of Anatomy & Cell Biology, McGill University, Montréal, Québec, Canada
| | - Huanquan Zheng
- Department of Biology, McGill University, Montréal, Québec, Canada
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Wan J, Basu K, Mui J, Vali H, Zheng H, Laliberté JF. Ultrastructural Characterization of Turnip Mosaic Virus-Induced Cellular Rearrangements Reveals Membrane-Bound Viral Particles Accumulating in Vacuoles. J Virol 2015. [PMID: 26423955 DOI: 10.1128/jvi.02138.15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2023] Open
Abstract
UNLABELLED Positive-strand RNA [(+) RNA] viruses remodel cellular membranes to facilitate virus replication and assembly. In the case of turnip mosaic virus (TuMV), the viral membrane protein 6K2 plays an essential role in endomembrane alterations. Although 6K2-induced membrane dynamics have been widely studied by confocal microscopy, the ultrastructure of this remodeling has not been extensively examined. In this study, we investigated the formation of TuMV-induced membrane changes by chemical fixation and high-pressure freezing/freeze substitution (HPF/FS) for transmission electron microscopy at different times of infection. We observed the formation of convoluted membranes connected to rough endoplasmic reticulum (rER) early in the infection process, followed by the production of single-membrane vesicle-like (SMVL) structures at the midstage of infection. Both SMVL and double-membrane vesicle-like structures with electron-dense cores, as well as electron-dense bodies, were found late in the infection process. Immunogold labeling results showed that the vesicle-like structures were 6K2 tagged and suggested that only the SMVL structures were viral RNA replication sites. Electron tomography (ET) was used to regenerate a three-dimensional model of these vesicle-like structures, which showed that they were, in fact, tubules. Late in infection, we observed filamentous particle bundles associated with electron-dense bodies, which suggests that these are sites for viral particle assembly. In addition, TuMV particles were observed to accumulate in the central vacuole as membrane-associated linear arrays. Our work thus unravels the sequential appearance of distinct TuMV-induced membrane structures for viral RNA replication, viral particle assembly, and accumulation. IMPORTANCE Positive-strand RNA viruses remodel cellular membranes for different stages of the infection process, such as protein translation and processing, viral RNA synthesis, particle assembly, and virus transmission. The ultrastructure of turnip mosaic virus (TuMV)-induced membrane remodeling was investigated over several days of infection. The first change that was observed involved endoplasmic reticulum-connected convoluted membrane accumulation. This was followed by the formation of single-membrane tubules, which were shown to be viral RNA replication sites. Later in the infection process, double-membrane tubular structures were observed and were associated with viral particle bundles. In addition, TuMV particles were observed to accumulate in the central vacuole as membrane-associated linear arrays. This work thus unravels the sequential appearance of distinct TuMV-induced membrane structures for viral RNA replication, viral particle assembly, and accumulation.
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Affiliation(s)
- Juan Wan
- INRS-Institut Armand-Frappier, Laval, Québec, Canada
| | - Kaustuv Basu
- Facility for Electron Microscopy Research, McGill University, Montréal, Québec, Canada
| | - Jeannie Mui
- Facility for Electron Microscopy Research, McGill University, Montréal, Québec, Canada
| | - Hojatollah Vali
- Facility for Electron Microscopy Research, McGill University, Montréal, Québec, Canada Department of Anatomy & Cell Biology, McGill University, Montréal, Québec, Canada
| | - Huanquan Zheng
- Department of Biology, McGill University, Montréal, Québec, Canada
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63
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Biotechnological aspects of cytoskeletal regulation in plants. Biotechnol Adv 2015; 33:1043-62. [DOI: 10.1016/j.biotechadv.2015.03.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 03/03/2015] [Accepted: 03/09/2015] [Indexed: 11/23/2022]
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64
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Jiang J, Patarroyo C, Garcia Cabanillas D, Zheng H, Laliberté JF. The Vesicle-Forming 6K2 Protein of Turnip Mosaic Virus Interacts with the COPII Coatomer Sec24a for Viral Systemic Infection. J Virol 2015. [PMID: 25878114 DOI: 10.1128/jvi.00503-515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023] Open
Abstract
UNLABELLED Positive-sense RNA viruses remodel host cell endomembranes to generate quasi-organelles known as "viral factories" to coordinate diverse viral processes, such as genome translation and replication. It is also becoming clear that enclosing viral RNA (vRNA) complexes within membranous structures is important for virus cell-to-cell spread throughout the host. In plant cells infected by turnip mosaic virus (TuMV), a member of the family Potyviridae, peripheral motile endoplasmic reticulum (ER)-derived viral vesicles are produced that carry the vRNA to plasmodesmata for delivery into adjacent noninfected cells. The viral protein 6K2 is responsible for the formation of these vesicles, but how 6K2 is involved in their biogenesis is unknown. We show here that 6K2 is associated with cellular membranes. Deletion mapping and site-directed mutagenesis experiments defined a soluble N-terminal 12-amino-acid stretch, in particular a potyviral highly conserved tryptophan residue and two lysine residues that were important for vesicle formation. When the tryptophan residue was changed into an alanine in the viral polyprotein, virus replication still took place, albeit at a reduced level, but cell-to-cell movement of the virus was abolished. Yeast (Saccharomyces cerevisiae) two-hybrid and coimmunoprecipitation experiments showed that 6K2 interacted with Sec24a, a COPII coatomer component. Appropriately, TuMV systemic movement was delayed in an Arabidopsis thaliana mutant line defective in Sec24a. Intercellular movement of TuMV replication vesicles thus requires ER export of 6K2, which is mediated by the interaction of the N-terminal domain of the viral protein with Sec24a. IMPORTANCE Many plant viruses remodel the endoplasmic reticulum (ER) to generate vesicles that are associated with the virus replication complex. The viral protein 6K2 of turnip mosaic virus (TuMV) is known to induce ER-derived vesicles that contain vRNA as well as viral and host proteins required for vRNA synthesis. These vesicles not only sustain vRNA synthesis, they are also involved in the intercellular trafficking of vRNA. In this investigation, we found that the N-terminal soluble domain of 6K2 is required for ER export of the protein and for the formation of vesicles. ER export is not absolutely required for vRNA replication but is necessary for virus cell-to-cell movement. Furthermore, we found that 6K2 physically interacts with the COPII coatomer Sec24a and that an Arabidopsis thaliana mutant line with a defective Sec24a shows a delay in the systemic infection by TuMV.
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Affiliation(s)
- Jun Jiang
- INRS-Institut Armand-Frappier, Laval, Québec, Canada
| | - Camilo Patarroyo
- Department of Biology, McGill University, Montréal, Québec, Canada
| | | | - Huanquan Zheng
- Department of Biology, McGill University, Montréal, Québec, Canada
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Matevz R, Florence F, Michel T, Ion GA, Agnès D, Laurent G, Maja K, David D, Kristina G, Emmanuel J, Maja R. Fluorescently Tagged Potato virus Y: A Versatile Tool for Functional Analysis of Plant-Virus Interactions. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 28:739-50. [PMID: 25761209 DOI: 10.1094/mpmi-07-14-0218-ta] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Potato virus Y (PVY) is an economically important plant virus that infects Solanaceous crops such as tobacco and potato. To date, studies into the localization and movement of PVY in plants have been limited to detection of viral RNA or proteins ex vivo. Here, a PVY N605 isolate was tagged with green fluorescent protein (GFP), characterized and used for in vivo tracking. In Nicotiana tabacum cv. Xanthi, PVY N605-GFP was biologically comparable to nontagged PVY N605, stable through three plant-to-plant passages and persisted for four months in infected plants. GFP was detected before symptoms and fluorescence intensity correlated with PVY RNA concentrations. PVY N605-GFP provided in vivo tracking of long-distance movement, allowing estimation of the cell-to-cell movement rate of PVY in N. tabacum cv. Xanthi (7.1 ± 1.5 cells per hour). PVY N605-GFP was adequately stable in Solanum tuberosum cvs. Désirée and NahG-Désirée and able to infect S. tuberosum cvs. Bintje and Bea, Nicotiana benthamiana, and wild potato relatives. PVY N605-GFP is therefore a powerful tool for future studies of PVY-host interactions, such as functional analysis of viral and plant genes involved in viral movement.
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Affiliation(s)
- Rupar Matevz
- 1 National Institute of Biology, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Faurez Florence
- 2 INRA, UMR 1349 IGEPP, Domaine de la Motte F-35653, Le Rheu, France
- 3 FN3PT/RD3PT, 43-45 rue de Naples, 75008 Paris, France
| | - Tribodet Michel
- 2 INRA, UMR 1349 IGEPP, Domaine de la Motte F-35653, Le Rheu, France
| | | | - Delaunay Agnès
- 4 INRA-CIRAD-Montpellier SupAgro, UMR-BGPI TA A-54/K, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France
| | - Glais Laurent
- 2 INRA, UMR 1349 IGEPP, Domaine de la Motte F-35653, Le Rheu, France
- 3 FN3PT/RD3PT, 43-45 rue de Naples, 75008 Paris, France
| | - Kriznik Maja
- 1 National Institute of Biology, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Dobnik David
- 1 National Institute of Biology, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Gruden Kristina
- 1 National Institute of Biology, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Jacquot Emmanuel
- 4 INRA-CIRAD-Montpellier SupAgro, UMR-BGPI TA A-54/K, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France
| | - Ravnikar Maja
- 1 National Institute of Biology, Večna pot 111, 1000 Ljubljana, Slovenia
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66
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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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67
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The Vesicle-Forming 6K2 Protein of Turnip Mosaic Virus Interacts with the COPII Coatomer Sec24a for Viral Systemic Infection. J Virol 2015; 89:6695-710. [PMID: 25878114 DOI: 10.1128/jvi.00503-15] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 04/11/2015] [Indexed: 12/21/2022] Open
Abstract
UNLABELLED Positive-sense RNA viruses remodel host cell endomembranes to generate quasi-organelles known as "viral factories" to coordinate diverse viral processes, such as genome translation and replication. It is also becoming clear that enclosing viral RNA (vRNA) complexes within membranous structures is important for virus cell-to-cell spread throughout the host. In plant cells infected by turnip mosaic virus (TuMV), a member of the family Potyviridae, peripheral motile endoplasmic reticulum (ER)-derived viral vesicles are produced that carry the vRNA to plasmodesmata for delivery into adjacent noninfected cells. The viral protein 6K2 is responsible for the formation of these vesicles, but how 6K2 is involved in their biogenesis is unknown. We show here that 6K2 is associated with cellular membranes. Deletion mapping and site-directed mutagenesis experiments defined a soluble N-terminal 12-amino-acid stretch, in particular a potyviral highly conserved tryptophan residue and two lysine residues that were important for vesicle formation. When the tryptophan residue was changed into an alanine in the viral polyprotein, virus replication still took place, albeit at a reduced level, but cell-to-cell movement of the virus was abolished. Yeast (Saccharomyces cerevisiae) two-hybrid and coimmunoprecipitation experiments showed that 6K2 interacted with Sec24a, a COPII coatomer component. Appropriately, TuMV systemic movement was delayed in an Arabidopsis thaliana mutant line defective in Sec24a. Intercellular movement of TuMV replication vesicles thus requires ER export of 6K2, which is mediated by the interaction of the N-terminal domain of the viral protein with Sec24a. IMPORTANCE Many plant viruses remodel the endoplasmic reticulum (ER) to generate vesicles that are associated with the virus replication complex. The viral protein 6K2 of turnip mosaic virus (TuMV) is known to induce ER-derived vesicles that contain vRNA as well as viral and host proteins required for vRNA synthesis. These vesicles not only sustain vRNA synthesis, they are also involved in the intercellular trafficking of vRNA. In this investigation, we found that the N-terminal soluble domain of 6K2 is required for ER export of the protein and for the formation of vesicles. ER export is not absolutely required for vRNA replication but is necessary for virus cell-to-cell movement. Furthermore, we found that 6K2 physically interacts with the COPII coatomer Sec24a and that an Arabidopsis thaliana mutant line with a defective Sec24a shows a delay in the systemic infection by TuMV.
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68
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Wan J, Cabanillas DG, Zheng H, Laliberté JF. Turnip mosaic virus moves systemically through both phloem and xylem as membrane-associated complexes. PLANT PHYSIOLOGY 2015; 167:1374-88. [PMID: 25717035 PMCID: PMC4378181 DOI: 10.1104/pp.15.00097] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 02/23/2015] [Indexed: 05/08/2023]
Abstract
Plant viruses move systemically in plants through the phloem. They move as virions or as ribonucleic protein complexes, although it is not clear what these complexes are made of. The approximately 10-kb RNA genome of Turnip mosaic virus (TuMV) encodes a membrane protein, known as 6K2, that induces endomembrane rearrangements for the formation of viral replication factories. These factories take the form of vesicles that contain viral RNA (vRNA) and viral replication proteins. In this study, we report the presence of 6K2-tagged vesicles containing vRNA and the vRNA-dependent RNA polymerase in phloem sieve elements and in xylem vessels. Transmission electron microscopy observations showed the presence in the xylem vessels of vRNA-containing vesicles that were associated with viral particles. Stem-girdling experiments, which leave xylem vessels intact but destroy the surrounding tissues, confirmed that TuMV could establish a systemic infection of the plant by going through xylem vessels. Phloem sieve elements and xylem vessels from Potato virus X-infected plants also contained lipid-associated nonencapsidated vRNA, indicating that the presence of membrane-associated ribonucleic protein complexes in the phloem and xylem may not be limited to TuMV. Collectively, these studies indicate that viral replication factories could end up in the phloem and the xylem.
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Affiliation(s)
- Juan Wan
- Institut National de la Recherche Scientifique-Institut Armand-Frappier, Laval, Quebec, Canada H7V 1B7 (J.W., D.G.C., J.-F.L.); andDepartment of Biology, McGill University, Montreal, Quebec, Canada H3A 1B1 (H.Z.)
| | - Daniel Garcia Cabanillas
- Institut National de la Recherche Scientifique-Institut Armand-Frappier, Laval, Quebec, Canada H7V 1B7 (J.W., D.G.C., J.-F.L.); andDepartment of Biology, McGill University, Montreal, Quebec, Canada H3A 1B1 (H.Z.)
| | - Huanquan Zheng
- Institut National de la Recherche Scientifique-Institut Armand-Frappier, Laval, Quebec, Canada H7V 1B7 (J.W., D.G.C., J.-F.L.); andDepartment of Biology, McGill University, Montreal, Quebec, Canada H3A 1B1 (H.Z.)
| | - Jean-François Laliberté
- Institut National de la Recherche Scientifique-Institut Armand-Frappier, Laval, Quebec, Canada H7V 1B7 (J.W., D.G.C., J.-F.L.); andDepartment of Biology, McGill University, Montreal, Quebec, Canada H3A 1B1 (H.Z.)
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69
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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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70
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Abstract
Potyvirus is the largest genus of plant viruses causing significant losses in a wide range of crops. Potyviruses are aphid transmitted in a nonpersistent manner and some of them are also seed transmitted. As important pathogens, potyviruses are much more studied than other plant viruses belonging to other genera and their study covers many aspects of plant virology, such as functional characterization of viral proteins, molecular interaction with hosts and vectors, structure, taxonomy, evolution, epidemiology, and diagnosis. Biotechnological applications of potyviruses are also being explored. During this last decade, substantial advances have been made in the understanding of the molecular biology of these viruses and the functions of their various proteins. After a general presentation on the family Potyviridae and the potyviral proteins, we present an update of the knowledge on potyvirus multiplication, movement, and transmission and on potyvirus/plant compatible interactions including pathogenicity and symptom determinants. We end the review providing information on biotechnological applications of potyviruses.
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71
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Worrall EA, Wamonje FO, Mukeshimana G, Harvey JJ, Carr JP, Mitter N. Bean Common Mosaic Virus and Bean Common Mosaic Necrosis Virus: Relationships, Biology, and Prospects for Control. Adv Virus Res 2015; 93:1-46. [PMID: 26111585 DOI: 10.1016/bs.aivir.2015.04.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The closely related potyviruses Bean common mosaic virus (BCMV) and Bean common mosaic necrosis virus (BCMNV) are major constraints on common bean (Phaseolus vulgaris) production. Crop losses caused by BCMV and BCMNV impact severely not only on commercial scale cultivation of this high-value crop but also on production by smallholder farmers in the developing world, where bean serves as a key source of dietary protein and mineral nutrition. In many parts of the world, progress has been made in combating BCMV through breeding bean varieties possessing the I gene, a dominant gene conferring resistance to most BCMV strains. However, in Africa, and in particular in Central and East Africa, BCMNV is endemic and this presents a serious problem for deployment of the I gene because this virus triggers systemic necrosis (black root disease) in plants possessing this resistance gene. Information on these two important viruses is scattered throughout the literature from 1917 onward, and although reviews on resistance to BCMV and BCMNV exist, there is currently no comprehensive review on the biology and taxonomy of BCMV and BCMNV. In this chapter, we discuss the current state of our knowledge of these two potyviruses including fundamental aspects of classification and phylogeny, molecular biology, host interactions, transmission through seed and by aphid vectors, geographic distribution, as well as current and future prospects for the control of these important viruses.
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72
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Wan J, Laliberté JF. Membrane-associated virus replication complexes locate to plant conducting tubes. PLANT SIGNALING & BEHAVIOR 2015; 10:e1042639. [PMID: 25955489 PMCID: PMC4622829 DOI: 10.1080/15592324.2015.1042639] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Revised: 04/06/2015] [Accepted: 04/14/2015] [Indexed: 05/18/2023]
Abstract
It is generally accepted that in order to establish a systemic infection in a plant, viruses move from the initially infected cell to the vascular tissues by cell-to-cell movement through plasmodesmata (PD), and load into the vascular conducting tubes (i.e. phloem sieve elements and xylem vessel elements) for long-distance movement. The viral unit in these movements can be a virion or a yet-to-be-defined ribonucleic protein (RNP) complex. Using live-cell imaging, our laboratory has previously demonstrated that membrane-bound replication complexes move cell-to-cell during turnip mosaic virus (TuMV) infection. Our recent study shows that these membrane-bound replication complexes end up in the vascular conducting tubes, which is likely the case for potato virus X (PVX) also. The presence of TuMV-induced membrane complexes in xylem vessels suggests that viral components could also be found in other apoplastic regions of the plant, such as the intercellular space. This possibility may have implications regarding how we approach the study of plant innate immune responses against viruses.
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Affiliation(s)
- Juan Wan
- INRS-Institut Armand-Frappier; Laval; Québec, Canada
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73
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Affiliation(s)
- Jean-François Laliberté
- INRS–Institut Armand-Frappier, Institut National de la Recherche Scientifique, Laval, Québec H7V 1B7, Canada;
| | - Huanquan Zheng
- Department of Biology, McGill University, Montréal, Québec H3A 1B1, Canada;
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Ivanov KI, Eskelin K, Lõhmus A, Mäkinen K. Molecular and cellular mechanisms underlying potyvirus infection. J Gen Virol 2014; 95:1415-1429. [DOI: 10.1099/vir.0.064220-0] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Potyviruses represent one of the most economically important and widely distributed groups of plant viruses. Despite considerable progress towards understanding the cellular and molecular basis of their pathogenicity, many questions remain about the mechanisms by which potyviruses suppress host defences and create an optimal intracellular environment for viral translation, replication, assembly and spread. The review focuses on the multifunctional roles of potyviral proteins and their interplay with various host factors in different compartments of the infected cell. We place special emphasis on the recently discovered and currently putative mechanisms by which potyviruses subvert the normal functions of different cellular organelles in order to establish an efficient and productive infection.
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Affiliation(s)
- K. I. Ivanov
- Department of Food and Environmental Sciences, PO Box 56, 00014 University of Helsinki, Finland
| | - K. Eskelin
- Department of Food and Environmental Sciences, PO Box 56, 00014 University of Helsinki, Finland
| | - A. Lõhmus
- Department of Food and Environmental Sciences, PO Box 56, 00014 University of Helsinki, Finland
| | - K. Mäkinen
- Department of Food and Environmental Sciences, PO Box 56, 00014 University of Helsinki, Finland
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Mäkinen K, Hafrén A. Intracellular coordination of potyviral RNA functions in infection. FRONTIERS IN PLANT SCIENCE 2014; 5:110. [PMID: 24723931 PMCID: PMC3972461 DOI: 10.3389/fpls.2014.00110] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 03/07/2014] [Indexed: 05/26/2023]
Abstract
Establishment of an infection cycle requires mechanisms to allocate the genomes of (+)-stranded RNA viruses in a balanced ratio to translation, replication, encapsidation, and movement, as well as mechanisms to prevent translocation of viral RNA (vRNA) to cellular RNA degradation pathways. The ratio of vRNA allocated to various functions is likely balanced by the availability of regulatory proteins or competition of the interaction sites within regulatory ribonucleoprotein complexes. Due to the transient nature of viral processes and the interdependency between vRNA pathways, it is technically demanding to work out the exact molecular mechanisms underlying vRNA regulation. A substantial number of viral and host proteins have been identified that facilitate the steps that lead to the assembly of a functional potyviral RNA replication complex and their fusion with chloroplasts. Simultaneously with on-going viral replication, part of the replicated potyviral RNA enters movement pathways. Although not much is known about the processes of potyviral RNA release from viral replication complexes, the molecular interactions involved in these processes determine the fate of the replicated vRNA. Some viral and host cell proteins have been described that direct replicated potyviral RNA to translation to enable potyviral gene expression and productive infection. The antiviral defense of the cell causes vRNA degradation by RNA silencing. We hypothesize that also plant pathways involved in mRNA decay may have a role in the coordination of potyviral RNA expression. In this review, we discuss the roles of different potyviral and host proteins in the coordination of various potyviral RNA functions.
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Affiliation(s)
- Kristiina Mäkinen
- Department of Food and Environmental Sciences, University of HelsinkiHelsinki, Finland
| | - Anders Hafrén
- Department of Food and Environmental Sciences, University of HelsinkiHelsinki, Finland
- Department of Plant Biology and Forest Genetics, Swedish University of Agricultural SciencesUppsala, Sweden
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