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Chai M, Li L, Li Y, Yang Y, Wang Y, Jiang X, Luan Y, Li F, Cui H, Wang A, Xiang W, Wu X, Cheng X. The 6-kilodalton peptide 1 in plant viruses of the family Potyviridae is a viroporin. Proc Natl Acad Sci U S A 2024; 121:e2401748121. [PMID: 38739789 PMCID: PMC11127057 DOI: 10.1073/pnas.2401748121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Accepted: 04/09/2024] [Indexed: 05/16/2024] Open
Abstract
Potyviridae, the largest family of plant RNA viruses, includes many important pathogens that significantly reduce the yields of many crops worldwide. In this study, we report that the 6-kilodalton peptide 1 (6K1), one of the least characterized potyviral proteins, is an endoplasmic reticulum-localized protein. AI-assisted structure modeling and biochemical assays suggest that 6K1 forms pentamers with a central hydrophobic tunnel, can increase the cell membrane permeability of Escherichia coli and Nicotiana benthamiana, and can conduct potassium in Saccharomyces cerevisiae. An infectivity assay showed that viral proliferation is inhibited by mutations that affect 6K1 multimerization. Moreover, the 6K1 or its homologous 7K proteins from other viruses of the Potyviridae family also have the ability to increase cell membrane permeability and transmembrane potassium conductance. Taken together, these data reveal that 6K1 and its homologous 7K proteins function as viroporins in viral infected cells.
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Affiliation(s)
- Mengzhu Chai
- College of Plant Protection, Northeast Agricultural University, Harbin, Heilongjiang150030, China
| | - Lei Li
- College of Plant Protection, Northeast Agricultural University, Harbin, Heilongjiang150030, China
| | - Yong Li
- School of Life Science, Northeast Agricultural University, Harbin, Heilongjiang150030, China
| | - Yingshuai Yang
- College of Plant Protection, Northeast Agricultural University, Harbin, Heilongjiang150030, China
| | - Yuting Wang
- College of Plant Protection, Northeast Agricultural University, Harbin, Heilongjiang150030, China
| | - Xue Jiang
- College of Plant Protection, Northeast Agricultural University, Harbin, Heilongjiang150030, China
| | - Yameng Luan
- College of Plant Protection, Northeast Agricultural University, Harbin, Heilongjiang150030, China
| | - Fangfang Li
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing100193, China
| | - Hongguang Cui
- College of Plant Protection, Hainan University, Haikou570228, China
| | - Aiming Wang
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ONN5V 4T3, Canada
| | - Wensheng Xiang
- College of Plant Protection, Northeast Agricultural University, Harbin, Heilongjiang150030, China
| | - Xiaoyun Wu
- College of Plant Protection, Northeast Agricultural University, Harbin, Heilongjiang150030, China
| | - Xiaofei Cheng
- College of Plant Protection, Northeast Agricultural University, Harbin, Heilongjiang150030, China
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Li L, Wang G, Zhang Y, Wang W, Zhu Y, Lyu Y, Wang Y, Zhang Y, Hong N. The functions of triple gene block proteins and coat protein of apple stem pitting virus in viral cell-to-cell movement. MOLECULAR PLANT PATHOLOGY 2024; 25:e13392. [PMID: 37837244 PMCID: PMC10782654 DOI: 10.1111/mpp.13392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 09/14/2023] [Accepted: 09/19/2023] [Indexed: 10/15/2023]
Abstract
Apple stem pitting virus is a species in the genus Foveavirus in the family Betaflexiviridae. Apple stem pitting virus (ASPV) commonly infects apple and pear plants grown worldwide. In this study, by integrating bimolecular fluorescence complementation, split-ubiquitin-based membrane yeast two-hybrid, and Agrobacterium-mediated expression assays, the interaction relationships and the subcellular locations of ASPV proteins TGBp1-3 and CP in Nicotiana benthamiana leaf cells were determined. Proteins CP, TGBp1, TGBp2, and TGBp3 were self-interactable, and TGBp2 played a role in the formation of perinuclear viroplasm and enhanced the colocalization of TGBp3 with CP and TGBp1. We found that the plant microfilament and endoplasmic reticulum structures were involved in the production of TGBp3 and TGBp2 vesicles, and their disruption decreased the virus accumulation level in the systemic leaves. The TGBp3 motile vesicles functioned in delivering the viral ribonucleoprotein complexes to the plasma membrane. Two cysteine residues at sites 35 and 49 of the TGBp3 sorting signal were necessary for the diffusion of TGBp3-marked vesicles. Furthermore, our results revealed that TGBp1, TGBp2, and CP could increase plasmodesmal permeability and move to the adjacent cells. This study demonstrates an interaction network and a subcellular location map of four ASPV proteins and for the first time provides insight into the functions of these proteins in the movement of a foveavirus.
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Affiliation(s)
- Liu Li
- Key Laboratory of Plant Pathology of Hubei Province, College of Plant Science and TechnologyHuazhong Agricultural UniversityWuhanChina
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural CropsHuazhong Agricultural UniversityWuhanChina
| | - Guoping Wang
- Key Laboratory of Plant Pathology of Hubei Province, College of Plant Science and TechnologyHuazhong Agricultural UniversityWuhanChina
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural CropsHuazhong Agricultural UniversityWuhanChina
| | - Yue Zhang
- Key Laboratory of Plant Pathology of Hubei Province, College of Plant Science and TechnologyHuazhong Agricultural UniversityWuhanChina
| | - Wenjun Wang
- Key Laboratory of Plant Pathology of Hubei Province, College of Plant Science and TechnologyHuazhong Agricultural UniversityWuhanChina
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural CropsHuazhong Agricultural UniversityWuhanChina
| | - Yiting Zhu
- Key Laboratory of Plant Pathology of Hubei Province, College of Plant Science and TechnologyHuazhong Agricultural UniversityWuhanChina
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural CropsHuazhong Agricultural UniversityWuhanChina
| | - Yuzhuo Lyu
- Key Laboratory of Plant Pathology of Hubei Province, College of Plant Science and TechnologyHuazhong Agricultural UniversityWuhanChina
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural CropsHuazhong Agricultural UniversityWuhanChina
| | - Yanxiang Wang
- Key Laboratory of Plant Pathology of Hubei Province, College of Plant Science and TechnologyHuazhong Agricultural UniversityWuhanChina
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural CropsHuazhong Agricultural UniversityWuhanChina
| | - Yongle Zhang
- Key Laboratory of Plant Pathology of Hubei Province, College of Plant Science and TechnologyHuazhong Agricultural UniversityWuhanChina
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural CropsHuazhong Agricultural UniversityWuhanChina
| | - Ni Hong
- Key Laboratory of Plant Pathology of Hubei Province, College of Plant Science and TechnologyHuazhong Agricultural UniversityWuhanChina
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural CropsHuazhong Agricultural UniversityWuhanChina
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Atabekova AK, Lazareva EA, Lezzhov AA, Solovieva AD, Golyshev SA, Skulachev BI, Solovyev ID, Savitsky AP, Heinlein M, Morozov SY, Solovyev AG. Interaction between Movement Proteins of Hibiscus green spot virus. Viruses 2022; 14:v14122742. [PMID: 36560746 PMCID: PMC9780815 DOI: 10.3390/v14122742] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Revised: 12/05/2022] [Accepted: 12/07/2022] [Indexed: 12/13/2022] Open
Abstract
Movement proteins (MPs) of plant viruses enable the translocation of viral genomes from infected to healthy cells through plasmodesmata (PD). The MPs functions involve the increase of the PD permeability and routing of viral genome both to the PD entrance and through the modified PD. Hibiscus green spot virus encodes two MPs, termed BMB1 and BMB2, which act in concert to accomplish virus cell-to-cell transport. BMB1, representing an NTPase/helicase domain-containing RNA-binding protein, localizes to the cytoplasm and the nucleoplasm. BMB2 is a small hydrophobic protein that interacts with the endoplasmic reticulum (ER) membranes and induces local constrictions of the ER tubules. In plant cells, BMB2 localizes to PD-associated membrane bodies (PAMBs) consisting of modified ER tubules and directs BMB1 to PAMBs. Here, we demonstrate that BMB1 and BMB2 interact in vitro and in vivo, and that their specific interaction is essential for BMB2-directed targeting of BMB1 to PAMBs. Using mutagenesis, we show that the interaction involves the C-terminal BMB1 region and the N-terminal region of BMB2.
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Affiliation(s)
- Anastasia K. Atabekova
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119992 Moscow, Russia
- Department of Virology, Biological Faculty, Moscow State University, 119234 Moscow, Russia
| | - Ekaterina A. Lazareva
- Department of Virology, Biological Faculty, Moscow State University, 119234 Moscow, Russia
| | - Alexander A. Lezzhov
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119992 Moscow, Russia
| | - Anna D. Solovieva
- Department of Virology, Biological Faculty, Moscow State University, 119234 Moscow, Russia
| | - Sergei A. Golyshev
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119992 Moscow, Russia
| | - Boris I. Skulachev
- Department of Virology, Biological Faculty, Moscow State University, 119234 Moscow, Russia
| | - Ilya D. Solovyev
- A. N. Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, 119071 Moscow, Russia
| | - Alexander P. Savitsky
- A. N. Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, 119071 Moscow, Russia
| | - Manfred Heinlein
- Institute for Plant Molecular Biology (IBMP-CNRS), University of Strasbourg, 67000 Strasbourg, France
| | - Sergey Y. Morozov
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119992 Moscow, Russia
- Department of Virology, Biological Faculty, Moscow State University, 119234 Moscow, Russia
| | - Andrey G. Solovyev
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119992 Moscow, Russia
- Department of Virology, Biological Faculty, Moscow State University, 119234 Moscow, Russia
- All-Russia Research Institute of Agricultural Biotechnology, 127550 Moscow, Russia
- Correspondence: ; Tel.: +7-(495)-939-3198
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Bakhos-Douaihy D, Seaayfan E, Frachon N, Demaretz S, Kömhoff M, Laghmani K. Diacidic Motifs in the Carboxyl Terminus Are Required for ER Exit and Translocation to the Plasma Membrane of NKCC2. Int J Mol Sci 2022; 23:ijms232112761. [PMID: 36361553 PMCID: PMC9656672 DOI: 10.3390/ijms232112761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 10/18/2022] [Accepted: 10/21/2022] [Indexed: 11/25/2022] Open
Abstract
Mutations in the apical Na-K-2Cl co-transporter, NKCC2, cause type I Bartter syndrome (BS1), a life-threatening kidney disease. We have previously demonstrated that the BS1 variant Y998X, which deprives NKCC2 from its highly conserved dileucine-like motifs, compromises co-transporter surface delivery through ER retention mechanisms. However, whether these hydrophobic motifs are sufficient for anterograde trafficking of NKCC2 remains to be determined. Interestingly, sequence analysis of NKCC2 C-terminus revealed the presence of consensus di-acidic (D/E-X-D/E) motifs, 949EEE951 and 1019DAELE1023, located upstream and downstream of BS1 mutation Y998X, respectively. Di-acidic codes are involved in ER export of proteins through interaction with COPII budding machinery. Importantly, whereas mutating 949EEE951 motif to 949AEA951 had no effect on NKCC2 processing, mutating 1019DAE1021 to 1019AAA1021 heavily impaired complex-glycosylation and cell surface expression of the cotransporter in HEK293 and OKP cells. Most importantly, triple mutation of D, E and E residues of 1019DAELE1023 to 1019AAALA1023 almost completely abolished NKCC2 complex-glycosylation, suggesting that this mutant failed to exit the ER. Cycloheximide chase analysis demonstrated that the absence of the terminally glycosylated form of 1019AAALA1023 was caused by defects in NKCC2 maturation. Accordingly, co-immunolocalization experiments revealed that 1019AAALA1023 was trapped in the ER. Finally, overexpression of a dominant negative mutant of Sar1-GTPase abolished NKCC2 maturation and cell surface expression, clearly indicating that NKCC2 export from the ER is COPII-dependent. Hence, our data indicate that in addition to the di-leucine like motifs, NKCC2 uses di-acidic exit codes for export from the ER through the COPII-dependent pathway. We propose that any naturally occurring mutation of NKCC2 interfering with this pathway could form the molecular basis of BS1.
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Affiliation(s)
- Dalal Bakhos-Douaihy
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, F-75006 Paris, France
- CNRS-ERL8228, F-75006 Paris, France
| | - Elie Seaayfan
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, F-75006 Paris, France
- CNRS-ERL8228, F-75006 Paris, France
| | - Nadia Frachon
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, F-75006 Paris, France
- CNRS-ERL8228, F-75006 Paris, France
| | - Sylvie Demaretz
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, F-75006 Paris, France
- CNRS-ERL8228, F-75006 Paris, France
| | - Martin Kömhoff
- Division of Pediatric Nephrology and Transplantation, University Children’s Hospital, Philipps-University, 35043 Marburg, Germany
| | - Kamel Laghmani
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, F-75006 Paris, France
- CNRS-ERL8228, F-75006 Paris, France
- Correspondence:
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Jiang C, Shan S, Huang Y, Mao C, Zhang H, Li Y, Chen J, Wei Z, Sun Z. The C-Terminal Transmembrane Domain of Cowpea Mild Mottle Virus TGBp2 Is Critical for Plasmodesmata Localization and for Its Interaction With TGBp1 and TGBp3. Front Microbiol 2022; 13:860695. [PMID: 35495691 PMCID: PMC9051516 DOI: 10.3389/fmicb.2022.860695] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Accepted: 03/25/2022] [Indexed: 11/13/2022] Open
Abstract
The movement of some plant RNA viruses is mediated by triple gene block (TGB) proteins, which cooperate to transfer the viral genome from cell to cell through plasmodesmata. Here, we investigated the function of the TGB proteins of cowpea mild mottle virus (CPMMV; genus Carlavirus, family Betaflexiviridae), which causes severe damage to soybean production. Subcellular localization experiments demonstrated that TGBp1 and TGBp3 were localized to the endoplasmic reticulum (ER), plasmodesmata (PD) and nucleus in Nicotiana benthamiana leaves. TGBp2 was unusually localized to PD. In protein interaction assays TGBp2 significantly enhanced the interaction between TGBp3 and TGBp1. Interaction assays using deletion mutants showed that the C-terminal transmembrane (TM) domain of TGBp2 is critical for its localization to PD and for its interaction with TGBp1 and TGBp3.
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6
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Lazareva EA, Lezzhov AA, Chergintsev DA, Golyshev SA, Dolja VV, Morozov SY, Heinlein M, Solovyev AG. Reticulon-like properties of a plant virus-encoded movement protein. THE NEW PHYTOLOGIST 2021; 229:1052-1066. [PMID: 32866987 DOI: 10.1111/nph.16905] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 08/20/2020] [Indexed: 06/11/2023]
Abstract
Plant viruses encode movement proteins (MPs) that ensure the transport of viral genomes through plasmodesmata (PD) and use cell endomembranes, mostly the endoplasmic reticulum (ER), for delivery of viral genomes to PD and formation of PD-anchored virus replication compartments. Here, we demonstrate that the Hibiscus green spot virus BMB2 MP, an integral ER protein, induces constrictions of ER tubules, decreases the mobility of ER luminal content, and exhibits an affinity to highly curved membranes. These properties are similar to those described for reticulons, cellular proteins that induce membrane curvature to shape the ER tubules. Similar to reticulons, BMB2 adopts a W-like topology within the ER membrane. BMB2 targets PD and increases their size exclusion limit, and these BMB2 activities correlate with the ability to induce constrictions of ER tubules. We propose that the induction of ER constrictions contributes to the BMB2-dependent increase in PD permeability and formation of the PD-associated replication compartments, therefore facilitating the virus intercellular spread. Furthermore, we show that the ER tubule constrictions also occur in cells expressing TGB2, one of the three MPs of Potato virus X (PVX), and in PVX-infected cells, suggesting that reticulon-like MPs are employed by diverse RNA viruses.
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Affiliation(s)
- Ekaterina A Lazareva
- Department of Virology, Biological Faculty, Moscow State University, Moscow, 119234, Russia
| | - Alexander A Lezzhov
- Faculty of Bioengineering and Bioinformatics, Moscow State University, Moscow, 119991, Russia
| | - Denis A Chergintsev
- Department of Plant Physiology, Biological Faculty, Moscow State University, Moscow, 119234, Russia
| | - Sergei A Golyshev
- A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, 119992, Russia
| | - Valerian V Dolja
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331, USA
| | - Sergey Y Morozov
- Department of Virology, Biological Faculty, Moscow State University, Moscow, 119234, Russia
- A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, 119992, Russia
| | - Manfred Heinlein
- Institute for Plant Molecular Biology (IBMP-CNRS), University of Strasbourg, Strasbourg, 67000, France
| | - Andrey G Solovyev
- Department of Virology, Biological Faculty, Moscow State University, Moscow, 119234, Russia
- A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, 119992, Russia
- Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow, 119991, Russia
- Institute of Agricultural Biotechnology, Russian Academy of Agricultural Sciences, Moscow, 127550, Russia
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Levy A, Tilsner J. Creating Contacts Between Replication and Movement at Plasmodesmata - A Role for Membrane Contact Sites in Plant Virus Infections? FRONTIERS IN PLANT SCIENCE 2020; 11:862. [PMID: 32719692 PMCID: PMC7350983 DOI: 10.3389/fpls.2020.00862] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 05/27/2020] [Indexed: 05/23/2023]
Abstract
To infect their hosts and cause disease, plant viruses must replicate within cells and move throughout the plant both locally and systemically. RNA virus replication occurs on the surface of various cellular membranes, whose shape and composition become extensively modified in the process. Membrane contact sites (MCS) can mediate non-vesicular lipid-shuttling between different membranes and viruses co-opt components of these structures to make their membrane environment suitable for replication. Whereas animal viruses exit and enter cells when moving throughout their host, the rigid wall of plant cells obstructs this pathway and plant viruses therefore move between cells symplastically through plasmodesmata (PD). PD are membranous channels connecting nearly all plant cells and are now viewed to constitute a specialized type of endoplasmic reticulum (ER)-plasma membrane (PM) MCS themselves. Thus, both replication and movement of plant viruses rely on MCS. However, recent work also suggests that for some viruses, replication and movement are closely coupled at ER-PM MCS at the entrances of PD. Movement-coupled replication at PD may be distinct from the main bulk of replication and virus accumulation, which produces progeny virions for plant-to-plant transmission. Thus, MCS play a central role in plant virus infections, and may provide a link between two essential steps in the viral life cycle, replication and movement. Here, we provide an overview of plant virus-MCS interactions identified to date, and place these in the context of the connection between viral replication and cell-to-cell movement.
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Affiliation(s)
- Amit Levy
- Department of Plant Pathology, University of Florida, Gainesville, FL, United States
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL, United States
| | - Jens Tilsner
- Biomedical Sciences Research Complex, The University of St. Andrews, St. Andrews, United Kingdom
- Cell and Molecular Sciences, The James Hutton Institute, Dundee, United Kingdom
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Ur Rehman A, Li Z, Yang Z, Waqas M, Wang G, Xu W, Li F, Hong N. The Coat Protein of Citrus Yellow Vein Clearing Virus Interacts with Viral Movement Proteins and Serves as an RNA Silencing Suppressor. Viruses 2019; 11:E329. [PMID: 30959816 PMCID: PMC6520955 DOI: 10.3390/v11040329] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 03/27/2019] [Accepted: 04/04/2019] [Indexed: 01/29/2023] Open
Abstract
Citrus yellow vein clearing virus is a newly accepted member of the genus Mandarivirus in the family Alphaflexiviridae. The triple gene block proteins (TGBp1, TGBp2 and TGBp3) encoded by plant viruses in this family function on facilitating virus movement. However, the protein function of citrus yellow vein clearing virus (CYVCV) have never been explored. Here, we showed in both yeast two-hybrid (Y2H) and bimolecular fluorescence (BiFC) assays that the coat protein (CP), TGBp1 and TGBp2 of CYVCV are self-interacting. Its CP also interacts with all three TGB proteins, and TGBp1 and TGBp2 interact with each other but not with TGBp3. Furthermore, the viral CP colocalizes with TGBp1 and TGBp3 at the plasmodesmata (PD) of epidermal cells of Nicotiana benthamiana leaves, and TGBp1 can translocate TGBp2 from granular-like structures embedded within ER networks to the PD. The results suggest that these proteins could coexist at the PD of epidermal cells of N. benthamiana. Using Agrobacterium infiltration-mediated RNA silencing assays, we show that CYVCV CP is a strong RNA silencing suppressor (RSS) triggered by positive-sense green fluorescent protein (GFP) RNA. The presented results provide insights for further revealing the mechanism of the viral movement and suppression of RNA silencing.
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Affiliation(s)
- Atta Ur Rehman
- Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
- Key Laboratory of Horticultural Crop (Fruit Trees) Biology and Germplasm Creation of the Ministry of Agriculture, Wuhan 430070, China.
- Plant Pathology Section, Central Cotton Research Institute, Sakrand, Sindh 67210, Pakistan.
| | - Zhuoran Li
- Key Laboratory of Horticultural Plant Biology (MOE), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, China.
| | - Zuokun Yang
- Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
- Key Laboratory of Horticultural Crop (Fruit Trees) Biology and Germplasm Creation of the Ministry of Agriculture, Wuhan 430070, China.
| | - Muhammad Waqas
- Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
| | - Guoping Wang
- Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
- Key Laboratory of Horticultural Crop (Fruit Trees) Biology and Germplasm Creation of the Ministry of Agriculture, Wuhan 430070, China.
| | - Wenxing Xu
- Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
- Key Laboratory of Horticultural Crop (Fruit Trees) Biology and Germplasm Creation of the Ministry of Agriculture, Wuhan 430070, China.
| | - Feng Li
- Key Laboratory of Horticultural Plant Biology (MOE), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, China.
| | - Ni Hong
- Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
- Key Laboratory of Horticultural Crop (Fruit Trees) Biology and Germplasm Creation of the Ministry of Agriculture, Wuhan 430070, China.
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Wu X, Liu J, Chai M, Wang J, Li D, Wang A, Cheng X. The Potato Virus X TGBp2 Protein Plays Dual Functional Roles in Viral Replication and Movement. J Virol 2019; 93:e01635-18. [PMID: 30541845 PMCID: PMC6384063 DOI: 10.1128/jvi.01635-18] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 12/03/2018] [Indexed: 01/27/2023] Open
Abstract
Plant viruses usually encode one or more movement proteins (MP) to accomplish their intercellular movement. A group of positive-strand RNA plant viruses requires three viral proteins (TGBp1, TGBp2, and TGBp3) that are encoded by an evolutionarily conserved genetic module of three partially overlapping open reading frames (ORFs), termed the triple gene block (TGB). However, how these three viral movement proteins function cooperatively in viral intercellular movement is still elusive. Using a novel in vivo double-stranded RNA (dsRNA) labeling system, we showed that the dsRNAs generated by potato virus X (PVX) RNA-dependent RNA polymerase (RdRp) are colocalized with viral RdRp, which are further tightly covered by "chain mail"-like TGBp2 aggregates and localizes alongside TGBp3 aggregates. We also discovered that TGBp2 interacts with the C-terminal domain of PVX RdRp, and this interaction is required for the localization of TGBp3 and itself to the RdRp/dsRNA bodies. Moreover, we reveal that the central and C-terminal hydrophilic domains of TGBp2 are required to interact with viral RdRp. Finally, we demonstrate that knockout of the entire TGBp2 or the domain involved in interacting with viral RdRp attenuates both PVX replication and movement. Collectively, these findings suggest that TGBp2 plays dual functional roles in PVX replication and intercellular movement.IMPORTANCE Many plant viruses contain three partially overlapping open reading frames (ORFs), termed the triple gene block (TGB), for intercellular movement. However, how the corresponding three proteins coordinate their functions remains obscure. In the present study, we provided multiple lines of evidence supporting the notion that PVX TGBp2 functions as the molecular adaptor bridging the interaction between the RdRp/dsRNA body and TGBp3 by forming "chain mail"-like structures in the RdRp/dsRNA body, which can also enhance viral replication. Taken together, our results provide new insights into the replication and movement of PVX and possibly also other TGB-containing plant viruses.
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Affiliation(s)
- Xiaoyun Wu
- College of Agriculture, Northeast Agriculture University, Harbin, China
| | - Jiahui Liu
- College of Agriculture, Northeast Agriculture University, Harbin, China
| | - Mengzhu Chai
- College of Agriculture, Northeast Agriculture University, Harbin, China
| | - Jinhui Wang
- College of Agriculture, Northeast Agriculture University, Harbin, China
| | - Dalong Li
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Ministry of Agriculture, Northeast Agricultural University, Harbin, China
| | - Aiming Wang
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada
| | - Xiaofei Cheng
- College of Agriculture, Northeast Agriculture University, Harbin, China
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10
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Donchenko E, Trifonova E, Nikitin N, Atabekov J, Karpova O. Alternanthera mosaic potexvirus: Several Features, Properties, and Application. Adv Virol 2018; 2018:1973705. [PMID: 30018641 PMCID: PMC6029478 DOI: 10.1155/2018/1973705] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 05/23/2018] [Indexed: 11/18/2022] Open
Abstract
Alternanthera mosaic virus (AltMV) is a typical member of the Potexvirus genus in its morphology and genome structure; still it exhibits a number of unique features. They allow this virus to be considered a promising object for biotechnology. Virions and virus-like particles (VLPs) of AltMV are stable in a wide range of conditions, including sera of laboratory animals. AltMV VLPs can assemble at various pH and ionic strengths. Furthermore, AltMV virions and VLPs demonstrate high immunogenicity, enhancing the immune response to the target antigen thus offering the possibility of being used as potential adjuvants. Recently, for the first time for plant viruses, we showed the structural difference between morphologically similar viral and virus-like particles on AltMV virions and VLPs. In this review, we discuss the features of AltMV virions, AltMV VLP assembly, and their structure and properties, as well as the characteristics of AltMV isolates, host plants, infection symptoms, AltMV isolation and purification, genome structure, viral proteins, and AltMV-based vectors.
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Affiliation(s)
- Ekaterina Donchenko
- Department of Virology, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Ekaterina Trifonova
- Department of Virology, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Nikolai Nikitin
- Department of Virology, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Joseph Atabekov
- Department of Virology, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Olga Karpova
- Department of Virology, Lomonosov Moscow State University, Moscow 119234, Russia
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11
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Lazareva EA, Lezzhov AA, Golyshev SA, Morozov SY, Heinlein M, Solovyev AG. Similarities in intracellular transport of plant viral movement proteins BMB2 and TGB3. J Gen Virol 2017; 98:2379-2391. [PMID: 28869000 DOI: 10.1099/jgv.0.000914] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The cell-to-cell transport of many plant viruses through plasmodesmata requires viral movement proteins (MPs) encoded by a 'triple gene block' (TGB) and termed TGB1, TGB2 and TGB3. TGB3 is a small integral membrane protein that contains subcellular targeting signals and directs both TGB2 and the helicase domain-containing TGB1 protein to plasmodesmata-associated structures. Recently, we described a 'binary movement block' (BMB) coding for two MPs, BMB1 and BMB2. The BMB2 protein associates with endoplasmic reticulum (ER) membranes, accumulates at plasmodesmata-associated membrane bodies and directs the BMB1 helicase to these structures. TGB3 transport to cell peripheral bodies was previously shown to bypass the secretory pathway and involve a non-conventional mechanism. Here, we provide evidence that the intracellular transport of both poa semilatent virus TGB3 and hibiscus green spot virus BMB2 to plasmodesmata-associated sites can occur via lateral translocation along the ER membranes. Agrobacterium-mediated transient co-expression in Nicotiana benthamiana leaves revealed that green fluorescent protein (GFP)-fused actin-binding domains of Arabidopsis fimbrin (ABD2-GFP) and mouse talin (TAL-GFP) inhibited the subcellular targeting of TGB3 and BMB2 to plasmodesmata-associated bodies, which resulted in TGB3 and BMB2 accumulation in the cytoplasm in association with aberrant ER structures. Inhibition of COPII budding complex formation by the expression of a dominant-negative mutant of the small GTPase Sar1 had no detectable effect on BMB2 subcellular targeting, which therefore could occur without exit from the ER in COPII transport vesicles. Collectively, the presented data support the current view that plant viral MPs exploit the ER:actin network for their intracellular transport.
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Affiliation(s)
- Ekaterina A Lazareva
- Department of Virology, Biological Faculty, Moscow State University, Moscow, Russia
| | - Alexander A Lezzhov
- Department of Virology, Biological Faculty, Moscow State University, Moscow, Russia
| | - Sergey A Golyshev
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia
| | - Sergey Y Morozov
- Department of Virology, Biological Faculty, Moscow State University, Moscow, Russia
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia
| | - Manfred Heinlein
- Université de Strasbourg, CNRS, IBMP UPR 2357, F-67000 Strasbourg, France
| | - Andrey G Solovyev
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia
- Sechenov First Moscow State Medical University, Institute of Molecular Medicine, Moscow, Russia
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12
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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: 23] [Impact Index Per Article: 3.3] [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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13
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Singh S, Mittal A. Transmembrane Domain Lengths Serve as Signatures of Organismal Complexity and Viral Transport Mechanisms. Sci Rep 2016; 6:22352. [PMID: 26925972 PMCID: PMC4772119 DOI: 10.1038/srep22352] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 02/12/2016] [Indexed: 12/24/2022] Open
Abstract
It is known that membrane proteins are important in various secretory pathways, with
a possible role of their transmembrane domains (TMDs) as sorting determinant
factors. One key aspect of TMDs associated with various
“checkposts” (i.e. organelles) of intracellular trafficking
is their length. To explore possible linkages in organisms with varying
“complexity” and differences in TMD lengths of membrane
proteins associated with different organelles (such as Endoplasmic Reticulum, Golgi,
Endosomes, Nucleus, Plasma Membrane), we analyzed ~70000 membrane
protein sequences in over 300 genomes of fungi, plants, non-mammalian vertebrates
and mammals. We report that as we move from simpler to complex organisms, variation
in organellar TMD lengths decreases, especially compared to their respective plasma
membranes, with increasing organismal complexity. This suggests an evolutionary
pressure in modulating length of TMDs of membrane proteins with increasing
complexity of communication between sub-cellular compartments. We also report
functional applications of our findings by discovering remarkable distinctions in
TMD lengths of membrane proteins associated with different intracellular transport
pathways. Finally, we show that TMD lengths extracted from viral proteins can serve
as somewhat weak indicators of viral replication sites in plant cells but very
strong indicators of different entry pathways employed by animal viruses.
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Affiliation(s)
- Snigdha Singh
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Aditya Mittal
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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14
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Lezzhov AA, Gushchin VA, Lazareva EA, Vishnichenko VK, Morozov SY, Solovyev AG. Translation of the shallot virus X TGB3 gene depends on non-AUG initiation and leaky scanning. J Gen Virol 2015; 96:3159-3164. [PMID: 26296665 DOI: 10.1099/jgv.0.000248] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Triple gene block (TGB), a conserved gene module found in the genomes of many filamentous and rod-shaped plant viruses, encodes three proteins, TGB1, TGB2 and TGB3, required for viral cell-to-cell movement through plasmodesmata and systemic transport via the phloem. The genome of Shallot virus X, the type species of the genus Allexivirus, includes TGB1 and TGB2 genes, but contains no canonical ORF for TGB3 protein. However, a TGB3-like protein-encoding sequence lacking an AUG initiator codon has been found in the shallot virus X (ShVX) genome in a position typical for TGB3 genes. This putative TGB3 gene is conserved in all allexiviruses. Here, we carried out sequence analysis to predict possible non-AUG initiator codons in the ShVX TGB3-encoding sequence. We further used an agroinfiltration assay in Nicotiana benthamiana to confirm this prediction. Site-directed mutagenesis was used to demonstrate that the ShVX TGB3 could be translated on a bicistronic mRNA template via a leaky scanning mechanism.
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Affiliation(s)
- Alexander A Lezzhov
- Department of Genetics, Biotechnology, Plant Breeding and Seed Science, Russian State Agrarian University - Moscow Timiryazev Agricultural Academy, Moscow 127550, Russia
| | - Vladimir A Gushchin
- Department of Virology, Biological Faculty, Moscow State University, Moscow 119992, Russia
- Genetic Department, Russian Center of Forest Health, Pushkino 141207, Russia
| | - Ekaterina A Lazareva
- Department of Virology, Biological Faculty, Moscow State University, Moscow 119992, Russia
| | - Valery K Vishnichenko
- Institute of Agricultural Biotechnology, Russian Academy of Agricultural Sciences, Moscow 127550, Russia
| | - Sergey Y Morozov
- Department of Virology, Biological Faculty, Moscow State University, Moscow 119992, Russia
- Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119992, Russia
| | - Andrey G Solovyev
- Institute of Agricultural Biotechnology, Russian Academy of Agricultural Sciences, Moscow 127550, Russia
- Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119992, Russia
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15
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Liou MR, Hu CC, Chou YL, Chang BY, Lin NS, Hsu YH. Viral elements and host cellular proteins in intercellular movement of Bamboo mosaic virus. Curr Opin Virol 2015; 12:99-108. [PMID: 25951346 DOI: 10.1016/j.coviro.2015.04.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 04/15/2015] [Accepted: 04/17/2015] [Indexed: 12/23/2022]
Abstract
As a member of the genus Potexvirus, Bamboo mosaic virus (BaMV) also belongs to the plant viruses that encode triple gene block proteins (TGBps) for intercellular movement within the host plants. Recent studies of the movement mechanisms of BaMV have revealed similarities and differences between BaMV and other potexviruses. This review focuses on the general aspects of viral and host elements involved in BaMV movement, the interactions among these elements, and the possible pathways for intra- and intercellular trafficking of BaMV. Major features of BaMV trafficking that have not been demonstrated in other potexviruses include: (i) the involvement of replicase, (ii) fine regulation by coat protein phosphorylation, (iii) the key roles played by TGBp3, (iv) the use of virions as the major transported form, and (v) the involvement of specific host factors, such as Ser/Thr kinase-like protein of Nicotiana benthamiana. We also highlight areas for future study that will provide a more comprehensive understanding of the detailed interactions among viral movement proteins and host factors, as well as the regulatory mechanisms of virus movement. Finally, a model based on the current knowledge is proposed to depict the diverse abilities of BaMV to utilize a wide range of mechanisms for efficient intercellular movement.
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Affiliation(s)
- Ming-Ru Liou
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 40227, Taiwan
| | - Chung-Chi Hu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 40227, Taiwan
| | - Yuan-Lin Chou
- Institute of Biochemistry, National Chung Hsing University, Taichung 40227, Taiwan
| | - Ban-Yang Chang
- Institute of Biochemistry, National Chung Hsing University, Taichung 40227, Taiwan
| | - Na-Sheng Lin
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 40227, Taiwan; Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Yau-Heiu Hsu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 40227, Taiwan.
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16
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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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17
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Park MR, Jeong RD, Kim KH. Understanding the intracellular trafficking and intercellular transport of potexviruses in their host plants. FRONTIERS IN PLANT SCIENCE 2014; 5:60. [PMID: 24672528 PMCID: PMC3957223 DOI: 10.3389/fpls.2014.00060] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 02/06/2014] [Indexed: 05/22/2023]
Abstract
The movement of potexviruses through the cytoplasm to plasmodesmata (PD) and through PD to adjacent cells depends on the viral and host cellular proteins. Potexviruses encode three movement proteins [referred to as the triple gene block (TGB1-3)]. TGB1 protein moves cell-to-cell through PD and requires TGB2 and TGB3, which are endoplasmic reticulum (ER)-located proteins. TGB3 protein directs the movement of the ER-derived vesicles induced by TGB2 protein from the perinuclear ER to the cortical ER. TGB2 protein physically interacts with TGB3 protein in a membrane-associated form and also interacts with either coat protein (CP) or TGB1 protein at the ER network. Recent studies indicate that potexvirus movement involves the interaction between TGB proteins and CP with host proteins including membrane rafts. A group of host cellular membrane raft proteins, remorins, can serve as a counteracting membrane platform for viral ribonucleoprotein (RNP) docking and can thereby inhibit viral movement. The CP, which is a component of the RNP movement complex, is also critical for viral cell-to-cell movement through the PD. Interactions between TGB1 protein and/or the CP subunit with the 5'-terminus of genomic RNA [viral RNA (vRNA)] form RNP movement complexes and direct the movement of vRNAs through the PD. Recent studies show that tobacco proteins such as NbMPB2C or NbDnaJ-like proteins interact with the stem-loop 1 RNA located at the 5'-terminus of Potato virus X vRNA and regulate intracellular as well as intercellular movement. Although several host proteins that interact with vRNAs or viral proteins and that are crucial for vRNA transport have been screened and characterized, additional host proteins and details of viral movement remain to be characterized. In this review, we describe recent progress in understanding potexvirus movement within and between cells and how such movement is affected by interactions between vRNA/proteins and host proteins.
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Affiliation(s)
- Mi-Ri Park
- Department of Agricultural Biotechnology, Seoul National UniversitySeoul, South Korea
- Plant Genomics and Breeding Institute, Seoul National UniversitySeoul, South Korea
- Research Institute for Agriculture and Life Sciences, Seoul National UniversitySeoul, South Korea
| | - Rae-Dong Jeong
- Advanced Radiation Technology Institute, Korea Atomic Energy Research InstituteJeongeup, South Korea
| | - Kook-Hyung Kim
- Department of Agricultural Biotechnology, Seoul National UniversitySeoul, South Korea
- Plant Genomics and Breeding Institute, Seoul National UniversitySeoul, South Korea
- Research Institute for Agriculture and Life Sciences, Seoul National UniversitySeoul, South Korea
- *Correspondence: Kook-Hyung Kim, Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, South Korea e-mail:
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18
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Park MR, Seo JK, Kim KH. Viral and nonviral elements in potexvirus replication and movement and in antiviral responses. Adv Virus Res 2013; 87:75-112. [PMID: 23809921 DOI: 10.1016/b978-0-12-407698-3.00003-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In Potato virus X, a member of the genus Potexvirus, special sequences and structures at the 5' and 3' ends of the nontranslated region function as cis-acting elements for viral replication. These elements greatly affect interactions between viral RNAs and those between viral RNAs and host factors. The potexvirus genome encodes five open-reading frames. Viral replicase, which is required for the synthesis of viral RNA, binds viral RNA elements and host factors to form a viral replication complex at the host cellular membrane. The coat protein (CP) and three viral movement proteins (TGB1, TGB2, and TGB3) have critical roles in mediating cell-to-cell viral movement through plasmodesmata by virion formation or by nonvirion ribonucleoprotein (RNP) complex formation with viral movement proteins (TGBs). The RNP complex, like TGB1-CP-viral RNA, is associated with viral replicase and used for immediate reinitiation of viral replication in newly invaded cells. Higher plants have defense mechanisms against potexviruses such as Rx-mediated resistance and RNA silencing. The CP acts as an avirulence effector for plant defense mechanisms, while TGB1 functions as a viral suppressor of RNA silencing, which is the mechanism of innate immune resistance. Here, we describe recent findings concerning the involvement of viral and host factors in potexvirus replication and in antiviral responses to potexvirus infection.
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Affiliation(s)
- Mi-Ri Park
- Department of Agricultural Biotechnology, Plant Genomics and Breeding Institute, Seoul National University, Seoul, Republic of Korea
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19
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Tilsner J, Linnik O, Louveaux M, Roberts IM, Chapman SN, Oparka KJ. Replication and trafficking of a plant virus are coupled at the entrances of plasmodesmata. J Cell Biol 2013; 201:981-95. [PMID: 23798728 PMCID: PMC3691464 DOI: 10.1083/jcb.201304003] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Accepted: 05/16/2013] [Indexed: 02/04/2023] Open
Abstract
Plant viruses use movement proteins (MPs) to modify intercellular pores called plasmodesmata (PD) to cross the plant cell wall. Many viruses encode a conserved set of three MPs, known as the triple gene block (TGB), typified by Potato virus X (PVX). In this paper, using live-cell imaging of viral RNA (vRNA) and virus-encoded proteins, we show that the TGB proteins have distinct functions during movement. TGB2 and TGB3 established endoplasmic reticulum-derived membranous caps at PD orifices. These caps harbored the PVX replicase and nonencapsidated vRNA and represented PD-anchored viral replication sites. TGB1 mediated insertion of the viral coat protein into PD, probably by its interaction with the 5' end of nascent virions, and was recruited to PD by the TGB2/3 complex. We propose a new model of plant virus movement, which we term coreplicational insertion, in which MPs function to compartmentalize replication complexes at PD for localized RNA synthesis and directional trafficking of the virus between cells.
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Affiliation(s)
- Jens Tilsner
- Biomedical Sciences Research Complex, University of St Andrews, Fife KY16 9ST, Scotland, UK.
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20
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Jang C, Seo EY, Nam J, Bae H, Gim YG, Kim HG, Cho IS, Lee ZW, Bauchan GR, Hammond J, Lim HS. Insights into Alternanthera mosaic virus TGB3 Functions: Interactions with Nicotiana benthamiana PsbO Correlate with Chloroplast Vesiculation and Veinal Necrosis Caused by TGB3 Over-Expression. FRONTIERS IN PLANT SCIENCE 2013; 4:5. [PMID: 23386854 PMCID: PMC3560364 DOI: 10.3389/fpls.2013.00005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Accepted: 01/08/2013] [Indexed: 05/18/2023]
Abstract
Alternanthera mosaic virus (AltMV) triple gene block 3 (TGB3) protein is involved in viral movement. AltMV TGB3 subcellular localization was previously shown to be distinct from that of Potato virus X (PVX) TGB3, and a chloroplast binding domain identified; veinal necrosis and chloroplast vesiculation were observed in Nicotiana benthamiana when AltMV TGB3 was over-expressed from PVX. Plants with over-expressed TGB3 showed more lethal damage under dark conditions than under light. Yeast-two-hybrid analysis and bimolecular fluorescence complementation (BiFC) reveal that Arabidopsis thaliana PsbO1 has strong interactions with TGB3; N. benthamiana PsbO (NbPsbO) also showed obvious interaction signals with TGB3 through BiFC. These results demonstrate an important role for TGB3 in virus cell-to-cell movement and virus-host plant interactions. The Photosystem II oxygen-evolving complex protein PsbO interaction with TGB3 is presumed to have a crucial role in symptom development and lethal damage under dark conditions. In order to further examine interactions between AtPsbO1, NbPsbO, and TGB3, and to identify the binding domain(s) in TGB3 protein, BiFC assays were performed between AtPsbO1 or NbPsbO and various mutants of TGB3. Interactions with C-terminally deleted TGB3 were significantly weaker than those with wild-type TGB3, and both N-terminally deleted TGB3 and a TGB3 mutant previously shown to lose chloroplast interactions failed to interact detectably with PsbO in BiFC. To gain additional information about TGB3 interactions in AltMV-susceptible plants, we cloned 12 natural AltMV TGB3 sequence variants into a PVX expression vector to examine differences in symptom development in N. benthamiana. Symptom differences were observed on PVX over-expression, with all AltMV TGB3 variants showing more severe symptoms than the WT PVX control, but without obvious correlation to sequence differences.
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Affiliation(s)
- Chanyong Jang
- Department of Applied Biology, Chungnam National UniversityDaejeon, South Korea
| | - Eun-Young Seo
- Department of Applied Biology, Chungnam National UniversityDaejeon, South Korea
| | - Jiryun Nam
- Department of Applied Biology, Chungnam National UniversityDaejeon, South Korea
| | - Hanhong Bae
- School of Biotechnology, Yeungnam UniversityGyeongsan, South Korea
| | - Yeong Guk Gim
- Department of Applied Biology, Chungnam National UniversityDaejeon, South Korea
| | - Hong Gi Kim
- Department of Applied Biology, Chungnam National UniversityDaejeon, South Korea
| | - In Sook Cho
- National Institute of Horticultural and Herbal Science, Rural Development AdministrationSuwon, South Korea
| | - Zee-Won Lee
- Division of Life Science, Korea Basic Science InstituteDaejeon, South Korea
| | - Gary R. Bauchan
- Electron and Confocal Microscopy Unit, Beltsville Agricultural Research Center, Agricultural Research Service, United States Department of AgricultureBeltsville, MD, USA
| | - John Hammond
- Floral and Nursery Plants Research Unit, US National Arboretum, Agricultural Research Service, United States Department of AgricultureBeltsville, MD, USA
- *Correspondence: John Hammond, Floral and Nursery Plants Research Unit, US National Arboretum, United States Department of Agriculture, Agricultural Research Service, 10300 Baltimore Avenue, B-010A, Beltsville, MD 20705, USA. e-mail: ; Hyoun-Sub Lim, Department of Applied Biology, Chungnam National University, 79 Daehangno, Yuseong-gu, Daejeon 305-764, South Korea. e-mail:
| | - Hyoun-Sub Lim
- Department of Applied Biology, Chungnam National UniversityDaejeon, South Korea
- *Correspondence: John Hammond, Floral and Nursery Plants Research Unit, US National Arboretum, United States Department of Agriculture, Agricultural Research Service, 10300 Baltimore Avenue, B-010A, Beltsville, MD 20705, USA. e-mail: ; Hyoun-Sub Lim, Department of Applied Biology, Chungnam National University, 79 Daehangno, Yuseong-gu, Daejeon 305-764, South Korea. e-mail:
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21
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Zaarour N, Demaretz S, Defontaine N, Zhu Y, Laghmani K. Multiple evolutionarily conserved Di-leucine like motifs in the carboxyl terminus control the anterograde trafficking of NKCC2. J Biol Chem 2012. [PMID: 23105100 DOI: 10.1074/jbc.m112.399162.] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Mutations in the apical Na-K-2Cl co-transporter, NKCC2, cause type I Bartter syndrome, a life-threatening kidney disease. Yet the mechanisms underlying the regulation of NKCC2 trafficking in renal cells are scarcely known. We previously showed that naturally occurring mutations depriving NKCC2 of its distal COOH-terminal tail and interfering with the (1081)LLV(1083) motif result in defects in the ER exit of the co-transporter. Here we show that this motif is necessary but not sufficient for anterograde trafficking of NKCC2. Indeed, we have identified two additional hydrophobic motifs, (1038)LL(1039) and (1048)LI(1049), that are required for ER exit and surface expression of the co-transporter. Double mutations of (1038)LL(1039) or (1048)LI(1049) to di-alanines disrupted glycosylation and cell surface expression of NKCC2, independently of the expression system. Pulse-chase analysis demonstrated that the absence of the terminally glycosylated form of NKCC2 was not due to reduced synthesis or increased rates of degradation of mutant co-transporters, but was instead caused by defects in maturation. Co-immunolocalization experiments revealed that (1038)AA(1039) and (1048)AA(1049) were trapped mainly in the ER as indicated by extensive co-localization with the ER marker calnexin. Remarkably, among several analyzed motifs present in the NKCC2 COOH terminus, only those required for ER exit and surface expression of NKCC2 are evolutionarily conserved in all members of the SLC12A family, a group of cation-chloride co-transporters that are targets of therapeutic drugs and mutated in several human diseases. Based upon these data, we propose abnormal anterograde trafficking as a common mechanism associated with mutations depriving NKCC2, and also all other members of the SLC12A family, of their COOH terminus.
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Affiliation(s)
- Nancy Zaarour
- INSERM, Centre de Recherche des Cordeliers, UMRS872, Paris, France
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22
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Zaarour N, Demaretz S, Defontaine N, Zhu Y, Laghmani K. Multiple evolutionarily conserved Di-leucine like motifs in the carboxyl terminus control the anterograde trafficking of NKCC2. J Biol Chem 2012; 287:42642-53. [PMID: 23105100 DOI: 10.1074/jbc.m112.399162] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Mutations in the apical Na-K-2Cl co-transporter, NKCC2, cause type I Bartter syndrome, a life-threatening kidney disease. Yet the mechanisms underlying the regulation of NKCC2 trafficking in renal cells are scarcely known. We previously showed that naturally occurring mutations depriving NKCC2 of its distal COOH-terminal tail and interfering with the (1081)LLV(1083) motif result in defects in the ER exit of the co-transporter. Here we show that this motif is necessary but not sufficient for anterograde trafficking of NKCC2. Indeed, we have identified two additional hydrophobic motifs, (1038)LL(1039) and (1048)LI(1049), that are required for ER exit and surface expression of the co-transporter. Double mutations of (1038)LL(1039) or (1048)LI(1049) to di-alanines disrupted glycosylation and cell surface expression of NKCC2, independently of the expression system. Pulse-chase analysis demonstrated that the absence of the terminally glycosylated form of NKCC2 was not due to reduced synthesis or increased rates of degradation of mutant co-transporters, but was instead caused by defects in maturation. Co-immunolocalization experiments revealed that (1038)AA(1039) and (1048)AA(1049) were trapped mainly in the ER as indicated by extensive co-localization with the ER marker calnexin. Remarkably, among several analyzed motifs present in the NKCC2 COOH terminus, only those required for ER exit and surface expression of NKCC2 are evolutionarily conserved in all members of the SLC12A family, a group of cation-chloride co-transporters that are targets of therapeutic drugs and mutated in several human diseases. Based upon these data, we propose abnormal anterograde trafficking as a common mechanism associated with mutations depriving NKCC2, and also all other members of the SLC12A family, of their COOH terminus.
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Affiliation(s)
- Nancy Zaarour
- INSERM, Centre de Recherche des Cordeliers, UMRS872, Paris, France
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Yan F, Lu Y, Lin L, Zheng H, Chen J. The ability of PVX p25 to form RL structures in plant cells is necessary for its function in movement, but not for its suppression of RNA silencing. PLoS One 2012; 7:e43242. [PMID: 22916231 PMCID: PMC3420909 DOI: 10.1371/journal.pone.0043242] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 07/18/2012] [Indexed: 12/29/2022] Open
Abstract
The p25 triple gene block protein of Potato virus X (PVX) is multifunctional, participating in viral movement and acting as a suppressor of RNA silencing. The cell-to-cell movement of PVX is known to depend on the suppression function of p25. GFP-fused p25 accumulates in rod-like (RL) structures with intense fluorescence in cells. By monitoring the location of fluorescence at different times, we have now shown that the RL structure is composed of filaments. P25 mutants without the conditional ability to recover movement function could not form RL structures while the mutants that had the ability did form the structure, suggesting that the ability of p25 to form RL structures is necessary for its function in cell-to-cell movement, but not for its suppressor function. Moreover, chemical inhibition of microfilaments in cells destroyed the formation of the complete RL structure. Additionally, TGBp2 and TGBp3 were recruited into the RL structure, suggesting a relationship between the TGBps in virus movement.
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Affiliation(s)
- Fei Yan
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
- Key Laboratory of Biotechnology in Plant Protection (Ministry of China), Zhejiang Academy of Agricultural Sciences, Hangzhou, China
- Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Yuwen Lu
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
- Key Laboratory of Biotechnology in Plant Protection (Ministry of China), Zhejiang Academy of Agricultural Sciences, Hangzhou, China
- Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Lin Lin
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
- Key Laboratory of Biotechnology in Plant Protection (Ministry of China), Zhejiang Academy of Agricultural Sciences, Hangzhou, China
- Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Hongying Zheng
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
- Key Laboratory of Biotechnology in Plant Protection (Ministry of China), Zhejiang Academy of Agricultural Sciences, Hangzhou, China
- Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Jianping Chen
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
- Key Laboratory of Biotechnology in Plant Protection (Ministry of China), Zhejiang Academy of Agricultural Sciences, Hangzhou, China
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Aikin R, Cervantes A, D'Angelo G, Ruel L, Lacas-Gervais S, Schaub S, Thérond P. A genome-wide RNAi screen identifies regulators of cholesterol-modified hedgehog secretion in Drosophila. PLoS One 2012; 7:e33665. [PMID: 22432040 PMCID: PMC3303847 DOI: 10.1371/journal.pone.0033665] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Accepted: 02/14/2012] [Indexed: 12/12/2022] Open
Abstract
Hedgehog (Hh) proteins are secreted molecules that function as organizers in animal development. In addition to being palmitoylated, Hh is the only metazoan protein known to possess a covalently-linked cholesterol moiety. The absence of either modification severely disrupts the organization of numerous tissues during development. It is currently not known how lipid-modified Hh is secreted and released from producing cells. We have performed a genome-wide RNAi screen in Drosophila melanogaster cells to identify regulators of Hh secretion. We found that cholesterol-modified Hh secretion is strongly dependent on coat protein complex I (COPI) but not COPII vesicles, suggesting that cholesterol modification alters the movement of Hh through the early secretory pathway. We provide evidence that both proteolysis and cholesterol modification are necessary for the efficient trafficking of Hh through the ER and Golgi. Finally, we identified several putative regulators of protein secretion and demonstrate a role for some of these genes in Hh and Wingless (Wg) morphogen secretion in vivo. These data open new perspectives for studying how morphogen secretion is regulated, as well as provide insight into regulation of lipid-modified protein secretion.
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Affiliation(s)
- Reid Aikin
- CNRS UMR 7277, Inserm UMR 1091, Institut de Biologie Valrose (iBV), Centre de Biochimie, Nice, France
- Université de Nice-Sophia Antipolis, Nice, France
| | - Alexandra Cervantes
- CNRS UMR 7277, Inserm UMR 1091, Institut de Biologie Valrose (iBV), Centre de Biochimie, Nice, France
- Université de Nice-Sophia Antipolis, Nice, France
| | - Gisela D'Angelo
- CNRS UMR 7277, Inserm UMR 1091, Institut de Biologie Valrose (iBV), Centre de Biochimie, Nice, France
- Université de Nice-Sophia Antipolis, Nice, France
| | - Laurent Ruel
- CNRS UMR 7277, Inserm UMR 1091, Institut de Biologie Valrose (iBV), Centre de Biochimie, Nice, France
- Université de Nice-Sophia Antipolis, Nice, France
| | - Sandra Lacas-Gervais
- Centre Commun de Microscopie Appliquée (CCMA), Université de Nice-Sophia Antipolis, Nice, France
| | - Sébastien Schaub
- CNRS UMR 7277, Inserm UMR 1091, Institut de Biologie Valrose (iBV), Centre de Biochimie, Nice, France
- Université de Nice-Sophia Antipolis, Nice, France
| | - Pascal Thérond
- CNRS UMR 7277, Inserm UMR 1091, Institut de Biologie Valrose (iBV), Centre de Biochimie, Nice, France
- Université de Nice-Sophia Antipolis, Nice, France
- * E-mail:
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Tilsner J, Linnik O, Wright KM, Bell K, Roberts AG, Lacomme C, Santa Cruz S, Oparka KJ. The TGB1 movement protein of Potato virus X reorganizes actin and endomembranes into the X-body, a viral replication factory. PLANT PHYSIOLOGY 2012; 158:1359-70. [PMID: 22253256 PMCID: PMC3291258 DOI: 10.1104/pp.111.189605] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Accepted: 01/13/2012] [Indexed: 05/18/2023]
Abstract
Potato virus X (PVX) requires three virally encoded proteins, the triple gene block (TGB), for movement between cells. TGB1 is a multifunctional protein that suppresses host gene silencing and moves from cell to cell through plasmodesmata, while TGB2 and TGB3 are membrane-spanning proteins associated with endoplasmic reticulum-derived granular vesicles. Here, we show that TGB1 organizes the PVX "X-body," a virally induced inclusion structure, by remodeling host actin and endomembranes (endoplasmic reticulum and Golgi). Within the X-body, TGB1 forms helically arranged aggregates surrounded by a reservoir of the recruited host endomembranes. The TGB2/3 proteins reside in granular vesicles within this reservoir, in the same region as nonencapsidated viral RNA, while encapsidated virions accumulate at the outer (cytoplasmic) face of the X-body, which comprises a highly organized virus "factory." TGB1 is both necessary and sufficient to remodel host actin and endomembranes and to recruit TGB2/3 to the X-body, thus emerging as the central orchestrator of the X-body. Our results indicate that the actin/endomembrane-reorganizing properties of TGB1 function to compartmentalize the viral gene products of PVX infection.
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Affiliation(s)
| | | | | | | | | | | | | | - Karl J. Oparka
- Institute of Molecular Plant Sciences, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom (J.T., O.L., K.B., C.L., K.J.O.); and The James Hutton Institute, Invergowrie, Dundee DD2 5DA, United Kingdom (K.M.W., A.G.R., S.S.C.)
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26
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Solovyev AG, Schiemann J, Morozov SY. Microscopic analysis of severe structural rearrangements of the plant endoplasmic reticulum and Golgi caused by overexpression of Poa semilatent virus movement protein. ScientificWorldJournal 2012; 2012:416076. [PMID: 22272174 PMCID: PMC3259505 DOI: 10.1100/2012/416076] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Accepted: 11/24/2011] [Indexed: 12/29/2022] Open
Abstract
Cell-to-cell transport of plant viruses is mediated by virus-encoded movement proteins and occurs through plasmodesmata interconnecting neighboring cells in plant tissues. Three movement proteins coded by the "triple gene block" (TGB) and named TGBp1, TGBp2 and TGBp3 have distinct functions in viral transport. TGBp1 binds viral genomic RNAs to form ribonucleoprotein complexes representing the transport form of viral genome, while TGBp2 and TGBp3 are necessary for intracellular delivery of such complexes to plasmodesmata. Recently, it was revealed that overexpression of Potato virus X TGBp3 triggers the unfolded protein response mitigating the endoplasmic reticulum (ER) stress leading to cell death if this protein reaches high levels in the ER. Here we report microscopic studies of the influence of the Poa semilatent hordeivirus TGBp3 overexpressed in Nicotiana benthamiana epidermal cells by particle bombardment on cell endomembranes and demonstrate that the protein C-terminal transmembrane segment contains a determinant responsible for vesiculation and coalescence of the endoplasmic reticulum and Golgi presumably accompanying the ER stress that can be induced upon high-level TGBp3 expression.
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Affiliation(s)
- Andrey G. Solovyev
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119992 Moscow, Russia
- Institute of Agricultural Biotechnology, Russian Academy of Agricultural Sciences, Timiryazevskaya 42, 127550 Moscow, Russia
| | - Joachim Schiemann
- Julius Kühn Institute (JKI), Federal Research Centre for Cultivated Plants, Institute for Biosafety of Genetically Modified Plants, Erwin-Baur-Street 27, 06484 Quedlinburg, Germany
| | - Sergey Y. Morozov
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119992 Moscow, Russia
- Department of Virology, Biological Faculty, Moscow State University, 119992 Moscow, Russia
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27
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Solovyev AG, Kalinina NO, Morozov SY. Recent advances in research of plant virus movement mediated by triple gene block. FRONTIERS IN PLANT SCIENCE 2012; 3:276. [PMID: 23248633 PMCID: PMC3520053 DOI: 10.3389/fpls.2012.00276] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Accepted: 11/23/2012] [Indexed: 05/19/2023]
Abstract
The aim of this short review was to summarize recent advances in the field of viral cell-to-cell movement mediated by the triple gene block (TGB). The growing body of new research has uncovered links between virus cell-to-cell trafficking and replication, silencing suppression, virus spread over the plant, as well as suggested the roles of nucleus/nucleolus in plant virus transport and revealed protein-membrane associations occurring during subcellular targeting and cell-to-cell movement. In this context, our review briefly summarized current views on several potentially important functions of TGB proteins and on the development of new experimental systems that improved understanding of the molecular events during TGB-mediated virus movement.
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Affiliation(s)
- Andrey G. Solovyev
- Belozersky Institute of Physico-Chemical Biology, Moscow State UniversityMoscow, Russia
| | - Natalia O. Kalinina
- Belozersky Institute of Physico-Chemical Biology, Moscow State UniversityMoscow, Russia
| | - Sergey Y. Morozov
- Belozersky Institute of Physico-Chemical Biology, Moscow State UniversityMoscow, Russia
- *Correspondence: Sergey Y. Morozov, Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119992, Russia. e-mail:
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28
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Lu Y, Yan F, Guo W, Zheng H, Lin L, Peng J, Adams MJ, Chen J. Garlic virus X 11-kDa protein granules move within the cytoplasm and traffic a host protein normally found in the nucleolus. MOLECULAR PLANT PATHOLOGY 2011; 12:666-76. [PMID: 21726366 PMCID: PMC6640471 DOI: 10.1111/j.1364-3703.2010.00699.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The subcellular localization of the 11-kDa protein (p11) encoded by ORF3 of Garlic virus X (GarVX; genus Allexivirus, family Alphaflexiviridae) was examined by confocal microscopy. Granules with intense fluorescence were visible on the endoplasmic reticulum when p11 fused with green or red fluorescent protein (GFP or RFP) was expressed in epidermal cells of Nicotiana benthamiana. Moreover, the p11-RFP granules moved in the cytoplasm, along the cell periphery and through the cell membranes to adjacent cells. A 17-kDa protein (p17) of garlic interacting with p11 was identified by yeast two-hybridization and bimolecular fluorescence complementation assay. When p17 fused to GFP was expressed in epidermal cells of N. benthamiana, it localized to the nucleolus. However, in the presence of GarVX p11, the distribution of p17 changed to that of p11, but did not appear to affect the pattern of movement of p11.
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Affiliation(s)
- Yuwen Lu
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, MOA and Zhejiang Provincial Key Laboratory of Plant Virology, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
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29
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Schoelz JE, Harries PA, Nelson RS. Intracellular transport of plant viruses: finding the door out of the cell. MOLECULAR PLANT 2011; 4:813-31. [PMID: 21896501 PMCID: PMC3183398 DOI: 10.1093/mp/ssr070] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 07/18/2011] [Indexed: 05/03/2023]
Abstract
Plant viruses are a class of plant pathogens that specialize in movement from cell to cell. As part of their arsenal for infection of plants, every virus encodes a movement protein (MP), a protein dedicated to enlarging the pore size of plasmodesmata (PD) and actively transporting the viral nucleic acid into the adjacent cell. As our knowledge of intercellular transport has increased, it has become apparent that viruses must also use an active mechanism to target the virus from their site of replication within the cell to the PD. Just as viruses are too large to fit through an unmodified plasmodesma, they are also too large to be freely diffused through the cytoplasm of the cell. Evidence has accumulated now for the involvement of other categories of viral proteins in intracellular movement in addition to the MP, including viral proteins originally associated with replication or gene expression. In this review, we will discuss the strategies that viruses use for intracellular movement from the replication site to the PD, in particular focusing on the role of host membranes for intracellular transport and the coordinated interactions between virus proteins within cells that are necessary for successful virus spread.
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Affiliation(s)
- James E. Schoelz
- Division of Plant Sciences, University of Missouri, Columbia, MO 65211, USA
| | - Phillip A. Harries
- Department of Biology, Pittsburg State University, Pittsburg, KS 66762, USA
| | - Richard S. Nelson
- Plant Biology Division, The Samuel Roberts Noble Foundation, Inc., Ardmore, OK 73401, USA
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30
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Ye C, Dickman MB, Whitham SA, Payton M, Verchot J. The unfolded protein response is triggered by a plant viral movement protein. PLANT PHYSIOLOGY 2011; 156:741-55. [PMID: 21474436 PMCID: PMC3177272 DOI: 10.1104/pp.111.174110] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Accepted: 04/04/2011] [Indexed: 05/17/2023]
Abstract
Infection with Potato virus X (PVX) in Nicotiana benthamiana plants leads to increased transcript levels of several stress-related host genes, including basic-region leucine zipper 60 (bZIP60), SKP1, ER luminal binding protein (BiP), protein disulfide isomerase (PDI), calreticulin (CRT), and calmodulin (CAM). bZIP60 is a key transcription factor that responds to endoplasmic reticulum (ER) stress and induces the expression of ER-resident chaperones (BiP, PDI, CRT, and CAM). SKP1 is a component of SCF (for SKP1-Cullin-F box protein) ubiquitin ligase complexes that target proteins for proteasomal degradation. Expression of PVX TGBp3 from a heterologous vector induces the same set of genes in N. benthamiana and Arabidopsis (Arabidopsis thaliana) leaves. Virus-induced gene silencing was employed to knock down the expression of bZIP60 and SKP1, and the number of infection foci on inoculated leaves was reduced and systemic PVX accumulation was altered. Silencing bZIP60 led to the suppression of BiP and SKP1 transcript levels, suggesting that bZIP60 might be an upstream signal transducer. Overexpression of TGBp3 led to localized necrosis, but coexpression of TGBp3 with BiP abrogated necrosis, demonstrating that the unfolded protein response alleviates ER stress-related cell death. Steady-state levels of PVX replicase and TGBp2 (which reside in the ER) proteins were unaltered by the presence of TGBp3, suggesting that TGBp3 does not contribute to their turnover. Taken together, PVX TGBp3-induced ER stress leads to up-regulation of bZIP60 and unfolded protein response-related gene expression, which may be important to regulate cellular cytotoxicity that could otherwise lead to cell death if viral proteins reach high levels in the ER.
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Affiliation(s)
| | | | | | | | - Jeanmarie Verchot
- Department of Entomology and Plant Pathology (C.Y., J.V.) and Department of Statistics (M.P.), Oklahoma State University, Stillwater, Oklahoma 74078; Institute for Plant Genomics and Biotechnology, Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas 77843 (M.B.D.); Department of Plant Pathology, Iowa State University, Ames, Iowa 50011 (S.A.W.)
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31
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Wu CH, Lee SC, Wang CW. Viral protein targeting to the cortical endoplasmic reticulum is required for cell-cell spreading in plants. ACTA ACUST UNITED AC 2011; 193:521-35. [PMID: 21518793 PMCID: PMC3087015 DOI: 10.1083/jcb.201006023] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Sorting signal-mediated oligomerization and localization of the viral protein TGBp3 to curved ER tubules is essential for viral movement between cells in plants. Many plant RNA viruses use their nonstructural proteins to target and move through the cortical endoplasmic reticulum (ER) tubules within the plant intercellular junction for cell-to-cell spreading. Most of these proteins, including the triple-gene-block 3 protein (TGBp3) of Potexvirus, are ER membrane proteins. We previously showed that TGBp3 of the Bamboo mosaic potexvirus partitions into tubular subdomains of the ER in both yeast and plants, but the mechanism and physiological significance of this localization is unclear. Here, we demonstrate that a sorting signal present in TGBp3 is necessary and sufficient for its oligomerization and for targeting integral membrane proteins into puncta within curved ER tubules. Mutations in the TGBp3 sorting signal impair viral spread, and plants infected with viruses harboring these mutants were either asymptomatic or had reduced symptoms. Thus, we propose that Potexvirus use the sorting signal in TGBp3 to target infectious viral derivatives to cortical ER tubules for transmission through the intercellular junctions in plants.
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Affiliation(s)
- Chih-Hang Wu
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
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32
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Shemyakina EA, Erokhina TN, Gorshkova EN, Schiemann J, Solovyev AG, Morozov SY. Formation of protein complexes containing plant virus movement protein TGBp3 is necessary for its intracellular trafficking. Biochimie 2011; 93:742-8. [PMID: 21251950 DOI: 10.1016/j.biochi.2011.01.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 01/11/2011] [Indexed: 12/11/2022]
Abstract
Cell-to-cell movement of Poa semilatent virus (genus Hordeivirus) in infected plants is mediated by three viral 'triple gene block' (TGB) proteins. One of those termed TGBp3 is an integral membrane protein essential for intracellular transport of other TGB proteins and viral genomic RNA to plasmodesmata. TGBp3 targeting to plasmodesmata-associated sites is believed to involve an unconventional mechanism which does not employ endoplasmic reticulum-derived transport vesicles. Previously TGBp3 has been shown to contain a composite transport signal consisting of the central hydrophilic protein region which includes a conserved pentapeptide YQDLN and the C-terminal transmembrane segment. This study demonstrates that these TGBp3 structural elements have distinct functions in protein transport. The YQDLN-containing region is essential for TGBp3 incorporation into high-molecular-mass protein complexes. In transient expression assay formation of such complexes is necessary for entering the TGBp3-specific pathway of intracellular transport and protein delivery to plasmodesmata-associated sites. In virus-infected plants TGBp3 is also found predominantly in the form of high-molecular-mass complexes. When the complex-formation function of YQDLN-containing region is disabled by a mutation, targeting to plasmodesmata-associated sites can be complemented by a heterologous peptide capable of formation multimeric complexes. The C-terminal transmembrane segment is found to be an essential signal of TGBp3 intracellular transport to peripheral sites.
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Affiliation(s)
- Elena A Shemyakina
- Department of Virology, Biological Faculty, Moscow State University, Moscow, Russia
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Tilsner J, Amari K, Torrance L. Plasmodesmata viewed as specialised membrane adhesion sites. PROTOPLASMA 2011; 248:39-60. [PMID: 20938697 DOI: 10.1007/s00709-010-0217-6] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Accepted: 09/27/2010] [Indexed: 05/20/2023]
Abstract
A significant amount of work has been expended to identify the elusive components of plasmodesmata (PD) to help understand their structure, as well as how proteins are targeted to them. This review focuses on the role that lipid membranes may play in defining PD both structurally and as subcellular targeting addresses. Parallels are drawn to findings in other areas of research which focus on the lateral segregation of membrane domains and the generation of three-dimensional organellar shapes from flat lipid bilayers. We conclude that consideration of the protein-lipid interactions in cell biological studies of PD components and PD-targeted proteins may yield new insights into some of the many open questions regarding these unique structures.
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Affiliation(s)
- Jens Tilsner
- Institute of Molecular Plant Sciences, University of Edinburgh, Mayfield Road, Edinburgh, EH9 3JH, UK.
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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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35
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Verchot-Lubicz J, Torrance L, Solovyev AG, Morozov SY, Jackson AO, Gilmer D. Varied movement strategies employed by triple gene block-encoding viruses. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:1231-47. [PMID: 20831404 DOI: 10.1094/mpmi-04-10-0086] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Several RNA virus genera belonging to the Virgaviridae and Flexiviridae families encode proteins organized in a triple gene block (TGB) that facilitate cell-to-cell and long-distance movement. The TGB proteins have been traditionally classified as hordei-like or potex-like based on phylogenetic comparisons and differences in movement mechanisms of the Hordeivirus and Potexvirus spp. However, accumulating data from other model viruses suggests that a revised framework is needed to accommodate the profound differences in protein interactions occurring during infection and ancillary capsid protein requirements for movement. The goal of this article is to highlight common features of the TGB proteins and salient differences in movement properties exhibited by individual viruses encoding these proteins. We discuss common and divergent aspects of the TGB transport machinery, describe putative nucleoprotein movement complexes, highlight recent data on TGB protein interactions and topological properties, and review membrane associations occurring during subcellular targeting and cell-to-cell movement. We conclude that the existing models cannot be used to explain all TGB viruses, and we propose provisional Potexvirus, Hordeivirus, and Pomovirus models. We also suggest areas that might profit from future research on viruses harboring this intriguing arrangement of movement proteins.
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Affiliation(s)
- Jeanmarie Verchot-Lubicz
- Oklahoma State University, Department of Entomology and Plant Pathology, Stillwater, OK 74078, USA.
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36
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Lim HS, Vaira AM, Bae H, Bragg JN, Ruzin SE, Bauchan GR, Dienelt MM, Owens RA, Hammond J. Mutation of a chloroplast-targeting signal in Alternanthera mosaic virus TGB3 impairs cell-to-cell movement and eliminates long-distance virus movement. J Gen Virol 2010; 91:2102-2115. [PMID: 20392901 DOI: 10.1099/vir.0.019448-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Cell-to-cell movement of potexviruses requires coordinated action of the coat protein and triple gene block (TGB) proteins. The structural properties of Alternanthera mosaic virus (AltMV) TGB3 were examined by methods differentiating between signal peptides and transmembrane domains, and its subcellular localization was studied by Agrobacterium-mediated transient expression and confocal microscopy. Unlike potato virus X (PVX) TGB3, AltMV TGB3 was not associated with the endoplasmic reticulum, and accumulated preferentially in mesophyll cells. Deletion and site-specific mutagenesis revealed an internal signal VL(17,18) of TGB3 essential for chloroplast localization, and either deletion of the TGB3 start codon or alteration of the chloroplast-localization signal limited cell-to-cell movement to the epidermis, yielding a virus that was unable to move into the mesophyll layer. Overexpression of AltMV TGB3 from either AltMV or PVX infectious clones resulted in veinal necrosis and vesiculation at the chloroplast membrane, a cytopathology not observed in wild-type infections. The distinctive mesophyll and chloroplast localization of AltMV TGB3 highlights the critical role played by mesophyll targeting in virus long-distance movement within plants.
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Affiliation(s)
- Hyoun-Sub Lim
- USDA-ARS, Plant Sciences Institute, Molecular Plant Pathology Laboratory, B-004, 10300 Baltimore Avenue, Beltsville, MD 20705, USA
| | - Anna Maria Vaira
- CNR, Istituto di Virologia Vegetale, Strada delle Cacce 73, Torino 10135, Italy
- USDA-ARS, Plant Sciences Institute, Molecular Plant Pathology Laboratory, B-004, 10300 Baltimore Avenue, Beltsville, MD 20705, USA
| | - Hanhong Bae
- School of Biotechnology, Yeungnam University, Geongsan 712-749, Republic of Korea
| | - Jennifer N Bragg
- USDA-ARS, Western Regional Research Center, 800 Buchanan Street, Albany, CA 94710, USA
| | - Steven E Ruzin
- University of California-Berkeley, CNR, 381 Koshland Hall, Berkeley, CA 94720, USA
| | - Gary R Bauchan
- USDA-ARS, Plant Sciences Institute, Electron and Confocal Microscopy Unit, B-465, 10300 Baltimore Avenue, Beltsville, MD 20705, USA
| | - Margaret M Dienelt
- USDA-ARS, Plant Sciences Institute, Molecular Plant Pathology Laboratory, B-004, 10300 Baltimore Avenue, Beltsville, MD 20705, USA
| | - Robert A Owens
- USDA-ARS, Plant Sciences Institute, Molecular Plant Pathology Laboratory, B-004, 10300 Baltimore Avenue, Beltsville, MD 20705, USA
| | - John Hammond
- USDA-ARS, Plant Sciences Institute, Molecular Plant Pathology Laboratory, B-004, 10300 Baltimore Avenue, Beltsville, MD 20705, USA
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37
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Lee SC, Wu CH, Wang CW. Traffic of a viral movement protein complex to the highly curved tubules of the cortical endoplasmic reticulum. Traffic 2010; 11:912-30. [PMID: 20374554 DOI: 10.1111/j.1600-0854.2010.01064.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Intracellular trafficking of the nonstructural movement proteins of plant viruses plays a crucial role in sequestering and targeting viral macromolecules in and between cells. Many of the movement proteins traffic in unconventional, yet mechanistically unknown, pathways to localize to the cell periphery. Here we study trafficking strategies associated with two integral membrane movement proteins TGBp2 and TGBp3 of Potexvirus in yeast. We demonstrate that this simple eukaryote recapitulates the targeting of TGBp2 to the peripheral bodies at the cell cortex by TGBp3. We found that these viral movement proteins traffic as an approximately 1:1 stoichiometric protein complex that further polymerizes to form punctate structures. Many punctate structures depart from the perinuclear endoplasmic reticulum (ER) and move along the tubular ER to the cortical ER, supporting that it involves a lateral sorting event via the ER network. Furthermore, the peripheral bodies are associated with cortical ER tubules that are marked by the ER shaping protein reticulon in both yeast and plants. Thus, our data support a model in which the peripheral bodies partition into and/or stabilize at highly curved membrane environments.
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Affiliation(s)
- Shu-Chuan Lee
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
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38
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Siddiqi S, Saleem U, Abumrad NA, Davidson NO, Storch J, Siddiqi SA, Mansbach CM. A novel multiprotein complex is required to generate the prechylomicron transport vesicle from intestinal ER. J Lipid Res 2010; 51:1918-28. [PMID: 20237389 DOI: 10.1194/jlr.m005611] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Dietary lipid absorption is dependent on chylomicron production whose rate-limiting step across the intestinal absorptive cell is the exit of chylomicrons from the endoplasmic reticulum (ER) in its ER-to-Golgi transport vesicle, the prechylomicron transport vesicle (PCTV). This study addresses the composition of the budding complex for PCTV. Immunoprecipitation (IP) studies from rat intestinal ER solubilized in Triton X-100 suggested that vesicle-associated membrane protein 7 (VAMP7), apolipoprotein B48 (apoB48), liver fatty acid-binding protein (L-FABP), CD36, and the COPII proteins were associated on incubation of the ER with cytosol and ATP. This association was confirmed by chromatography of the solubilized ER over Sephacryl S400-HR in which these constituents cochromatographed with an apparent kDa of 630. No multiprotein complex was detected when the ER was chromatographed in the absence of PCTV budding activity (resting ER or PKCzeta depletion of ER and cytosol). Treatment of the ER with anti-apoB48 or anti-VAMP7 antibodies or using gene disrupted L-FABP or CD36 mice all significantly inhibited PCTV generation. A smaller complex (no COPII proteins) was formed when only rL-FABP was used to bud PCTV. The data support the conclusion that the PCTV budding complex in intestinal ER is composed of VAMP7, apoB48, CD36, and L-FABP, plus the COPII proteins.
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Affiliation(s)
- Shahzad Siddiqi
- Division of Gastroenterology, Department of Medicine, University of Tennessee Health Science Center, Memphis, TN, USA
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39
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Epel BL. Plant viruses spread by diffusion on ER-associated movement-protein-rafts through plasmodesmata gated by viral induced host β-1,3-glucanases. Semin Cell Dev Biol 2009; 20:1074-81. [DOI: 10.1016/j.semcdb.2009.05.010] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2009] [Revised: 05/24/2009] [Accepted: 05/27/2009] [Indexed: 01/24/2023]
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40
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Minina EA, Erokhina TN, Garushyants SK, Solovyev AG, Morozov SY. Subcellular localization of the new plant protein 4/1 and analysis of heterologous protein-protein interactions indicate its ability for nuclear-cytoplasmic transport. DOKL BIOCHEM BIOPHYS 2009; 429:296-300. [PMID: 20101824 DOI: 10.1134/s1607672909060039] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- E A Minina
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, Moscow, 117997 Russia
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41
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Bamunusinghe D, Hemenway CL, Nelson RS, Sanderfoot AA, Ye CM, Silva MAT, Payton M, Verchot-Lubicz J. Analysis of potato virus X replicase and TGBp3 subcellular locations. Virology 2009; 393:272-85. [PMID: 19729179 DOI: 10.1016/j.virol.2009.08.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Revised: 07/09/2009] [Accepted: 08/02/2009] [Indexed: 10/20/2022]
Abstract
Potato virus X (PVX) infection leads to certain cytopathological modifications of the host endomembrane system. The subcellular location of the PVX replicase was previously unknown while the PVX TGBp3 protein was previously reported to reside in the ER. Using PVX infectious clones expressing the green fluorescent protein reporter, and antisera detecting the PVX replicase and host membrane markers, we examined the subcellular distribution of the PVX replicase in relation to the TGBp3. Confocal and electron microscopic observations revealed that the replicase localizes in membrane bound structures that derive from the ER. A subset of TGBp3 resides in the ER at the same location as the replicase. Sucrose gradient fractionation showed that the PVX replicase and TGBp3 proteins co-fractionate with ER marker proteins. This localization represents a region where both proteins may be synthesized and/or function. There is no evidence to indicate that either PVX protein moves into the Golgi apparatus. Cerulenin, a drug that inhibits de novo membrane synthesis, also inhibited PVX replication. These combined data indicate that PVX replication relies on ER-derived membrane recruitment and membrane proliferation.
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Affiliation(s)
- Devinka Bamunusinghe
- Department of Entomology and Plant Pathology, Noble Research Center, Oklahoma State University, Stillwater, OK 74078, USA.
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42
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Lin YH, Druffel KL, Whitworth J, Pavek MJ, Pappu HR. Molecular characterization of two potato virus S isolates from late-blight-resistant genotypes of potato (Solanum tuberosum). Arch Virol 2009; 154:1861-3. [DOI: 10.1007/s00705-009-0486-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2009] [Accepted: 07/28/2009] [Indexed: 11/27/2022]
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43
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Lim HS, Bragg JN, Ganesan U, Ruzin S, Schichnes D, Lee MY, Vaira AM, Ryu KH, Hammond J, Jackson AO. Subcellular localization of the barley stripe mosaic virus triple gene block proteins. J Virol 2009; 83:9432-48. [PMID: 19570874 PMCID: PMC2738231 DOI: 10.1128/jvi.00739-09] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2009] [Accepted: 06/22/2009] [Indexed: 02/07/2023] Open
Abstract
Barley stripe mosaic virus (BSMV) spreads from cell to cell through the coordinated actions of three triple gene block (TGB) proteins (TGB1, TGB2, and TGB3) arranged in overlapping open reading frames (ORFs). Our previous studies (D. M. Lawrence and A. O. Jackson, J. Virol. 75:8712-8723, 2001; D. M. Lawrence and A. O. Jackson, Mol. Plant Pathol. 2:65-75, 2001) have shown that each of these proteins is required for cell-to-cell movement in monocot and dicot hosts. We recently found (H.-S. Lim, J. N. Bragg, U. Ganesan, D. M. Lawrence, J. Yu, M. Isogai, J. Hammond, and A. O. Jackson, J. Virol. 82:4991-5006, 2008) that TGB1 engages in homologous interactions leading to the formation of a ribonucleoprotein complex containing viral genomic and messenger RNAs, and we have also demonstrated that TGB3 functions in heterologous interactions with TGB1 and TGB2. We have now used Agrobacterium tumefaciens-mediated protein expression in Nicotiana benthamiana leaf cells and site-specific mutagenesis to determine how TGB protein interactions influence their subcellular localization and virus spread. Confocal microscopy revealed that the TGB3 protein localizes at the cell wall (CW) in close association with plasmodesmata and that the deletion or mutagenesis of a single amino acid at the immediate C terminus can affect CW targeting. TGB3 also directed the localization of TGB2 from the endoplasmic reticulum to the CW, and this targeting was shown to be dependent on interactions between the TGB2 and TGB3 proteins. The optimal localization of the TGB1 protein at the CW also required TGB2 and TGB3 interactions, but in this context, site-specific TGB1 helicase motif mutants varied in their localization patterns. The results suggest that the ability of TGB1 to engage in homologous binding interactions is not essential for targeting to the CW. However, the relative expression levels of TGB2 and TGB3 influenced the cytosolic and CW distributions of TGB1 and TGB2. Moreover, in both cases, localization at the CW was optimal at the 10:1 TGB2-to-TGB3 ratios occurring in virus infections, and mutations reducing CW localization had corresponding effects on BSMV movement phenotypes. These data support a model whereby TGB protein interactions function in the subcellular targeting of movement protein complexes and the ability of BSMV to move from cell to cell.
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Affiliation(s)
- Hyoun-Sub Lim
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, FNPRU, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705, CNR, Istituto di Virologia Vegetale, Torino 10135, Italy, Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, South Korea
| | - Jennifer N. Bragg
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, FNPRU, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705, CNR, Istituto di Virologia Vegetale, Torino 10135, Italy, Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, South Korea
| | - Uma Ganesan
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, FNPRU, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705, CNR, Istituto di Virologia Vegetale, Torino 10135, Italy, Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, South Korea
| | - Steven Ruzin
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, FNPRU, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705, CNR, Istituto di Virologia Vegetale, Torino 10135, Italy, Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, South Korea
| | - Denise Schichnes
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, FNPRU, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705, CNR, Istituto di Virologia Vegetale, Torino 10135, Italy, Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, South Korea
| | - Mi Yeon Lee
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, FNPRU, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705, CNR, Istituto di Virologia Vegetale, Torino 10135, Italy, Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, South Korea
| | - Anna Maria Vaira
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, FNPRU, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705, CNR, Istituto di Virologia Vegetale, Torino 10135, Italy, Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, South Korea
| | - Ki Hyun Ryu
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, FNPRU, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705, CNR, Istituto di Virologia Vegetale, Torino 10135, Italy, Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, South Korea
| | - John Hammond
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, FNPRU, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705, CNR, Istituto di Virologia Vegetale, Torino 10135, Italy, Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, South Korea
| | - Andrew O. Jackson
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, FNPRU, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705, CNR, Istituto di Virologia Vegetale, Torino 10135, Italy, Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, South Korea
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44
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Jackson AO, Lim HS, Bragg J, Ganesan U, Lee MY. Hordeivirus replication, movement, and pathogenesis. ANNUAL REVIEW OF PHYTOPATHOLOGY 2009; 47:385-422. [PMID: 19400645 DOI: 10.1146/annurev-phyto-080508-081733] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The last Hordeivirus review appearing in this series 20 years ago focused on the comparative biology, relationships, and genome organization of members of the genus ( 68 ). Prior to the 1989 review, useful findings about the origin, disease occurrence, host ranges, and general biological properties of Barley stripe mosaic virus (BSMV) were summarized in three comprehensive reviews ( 26, 67, 107 ). Several recent reviews emphasizing contemporary molecular genetic findings also may be of interest to various readers ( 15, 37, 42, 69, 70, 88, 113 ). In the current review, we briefly reiterate the biological properties of the four members of the Hordeivirus genus and describe advances in our understanding of organization and expression of the viral genomes. We also discuss the infection processes and pathogenesis of the most extensively characterized Hordeiviruses and frame these advances in the broader context of viruses in other families that have encoded triple gene block proteins. In addition, an overview of recent advances in the use of BSMV for virus-induced gene silencing is presented.
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Affiliation(s)
- Andrew O Jackson
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA.
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45
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Rebelo AR, Niewiadomski S, Prosser SW, Krell P, Meng B. Subcellular localization of the triple gene block proteins encoded by a Foveavirus infecting grapevines. Virus Res 2008; 138:57-69. [PMID: 18804498 DOI: 10.1016/j.virusres.2008.08.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Revised: 08/13/2008] [Accepted: 08/14/2008] [Indexed: 11/25/2022]
Abstract
Grapevine rupestris stem pitting-associated virus (GRSPaV; Foveavirus; Flexiviridae) contains a positive-sense, ssRNA genome. GRSPaV occurs worldwide in grapes and is involved in the Rugose Wood disease complex. The GRSPaV genome contains the triple gene block (TGB), a genetic module present in several genera of plant RNA viruses. TGB encodes three proteins (TGBp1, TGBp2 and TGBp3) that are believed to work together to achieve intra- and inter-cellular transport of virions in infected plants. To reveal the subcellular localization of each TGB protein and to examine the impact that different fusion positions may have on the behavior of the native protein, we made a series of expression constructs and expressed the corresponding protein fusions in Nicotiana tabacum BY-2 cells and protoplasts. We demonstrated that TGBp1 had both a cytosolic and nuclear distribution. Two TGBp1 fusions (GFP fused at the N- or C-terminus) differ in subcellular distribution. Through the use of truncation mutants, we mapped TGBp1 regions responsible for the formation of two distinct types of aggregates. Sequence analyses predicted two and one transmembrane domains in TGBp2 and TGBp3, respectively. GFP fusions at either terminus of TGBp2 revealed identical localization to the ER network and ER-derived structures. In contrast, the two TGBp3 fusions to mRFP differed in localization. This is the first report on the subcellular localization of the viral proteins of a member of the Foveavirus genus.
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Affiliation(s)
- Ana Rita Rebelo
- Department of Molecular and Cellular Biology, College of Biological Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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46
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Hsu HT, Chou YL, Tseng YH, Lin YH, Lin TM, Lin NS, Hsu YH, Chang BY. Topological properties of the triple gene block protein 2 of Bamboo mosaic virus. Virology 2008; 379:1-9. [PMID: 18639913 DOI: 10.1016/j.virol.2008.06.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2008] [Revised: 06/11/2008] [Accepted: 06/17/2008] [Indexed: 12/01/2022]
Abstract
The triple gene block protein 2 (TGBp2) of Bamboo mosaic virus (BaMV) has been proposed to be a transmembrane protein; however, its features remain unclear. Here, we used biochemical approaches to determine its topological properties. Our data reveal that TGBp2 is mainly associated with the endoplasmic reticulum membrane. The resistance of TGBp2 in proteoliposomes, prepared from both the BaMV-infected tissues and in vitro reconstitution system, to both chemical extraction and trypsin digestion confirmed that it is indeed an integral membrane protein. On the basis of the minor change in the size of the major stable TGBp2-derived tryptic fragment from the monomeric TGBp2, as well as the sensitivity of the cysteine residues at the C-terminal tail of TGBp2 to maleimide modification, we suggest that TGBp2 adopts a topology with both its short N- and C-terminal tails exposed to the outer surface of the endoplasmic reticulum. Moreover, TGBp2 is able to self-assemble as revealed by the significant increase in multimeric TGBp2 when the TGBp2-containing proteoliposomes were treated with chemical crosslinker or oxidation agent.
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Affiliation(s)
- Hsiu-Ting Hsu
- Institute of Biochemistry, National Chung-Hsing University, Taichung 40227, Taiwan, Republic of China
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47
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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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48
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Abstract
Plant viruses spread from the initially infected cells to the rest of the plant in several distinct stages. First, the virus (in the form of virions or nucleic acid protein complexes) moves intracellularly from the sites of replication to plasmodesmata (PD, plant-specific intercellular membranous channels), the virus then transverses the PD to spread intercellularly (cell-to-cell movement). Long-distance movement of virus occurs through phloem sieve tubes. The processes of plant virus movement are controlled by specific viral movement proteins (MPs). No extensive sequence similarity has been found in MPs belonging to different plant virus taxonomic groups. Moreover, different MPs were shown to use different pathways and mechanisms for virus transport. Some viral transport systems require a single MP while others require additional virus-encoded proteins to transport viral genomes. In this review, we focus on the functions and properties of different classes of MPs encoded by RNA containing plant viruses.
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49
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Ohkawa A, Yamada M, Sayama H, Sugiyama N, Okuda S, Natsuaki T. Complete nucleotide sequence of a Japanese isolate of Chrysanthemum virus B (genus Carlavirus). Arch Virol 2007; 152:2253-8. [PMID: 17726637 DOI: 10.1007/s00705-007-1039-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2007] [Accepted: 06/27/2007] [Indexed: 11/30/2022]
Abstract
The complete nucleotide sequence of a Chrysanthemum virus B isolate from Japan (CVB-S) has been determined. The genomic RNA of CVB-S is 8,990 nucleotides long, excluding the poly(A) tail and, like that of other carlaviruses, contains six open reading frames (ORFs). Multiple alignment and phylogenetic analyses indicated that the phylogenetic relationship among members of the genus Carlavirus is very diverse, with phlox virus S being the closest relative of CVB. In aphid transmission tests, CVB-S was transmitted at a very low rate by Aphis gossypii, a new vector of the virus.
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Affiliation(s)
- A Ohkawa
- Faculty of Agriculture, Utsunomiya University, Utsunomiya, Japan
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50
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Samuels TD, Ju HJ, Ye CM, Motes CM, Blancaflor EB, Verchot-Lubicz J. Subcellular targeting and interactions among the Potato virus X TGB proteins. Virology 2007; 367:375-89. [PMID: 17610926 DOI: 10.1016/j.virol.2007.05.022] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2007] [Revised: 04/24/2007] [Accepted: 05/03/2007] [Indexed: 12/16/2022]
Abstract
Potato virus X (PVX) encodes three proteins named TGBp1, TGBp2, and TGBp3 which are required for virus cell-to-cell movement. To determine whether PVX TGB proteins interact during virus cell-cell movement, GFP was fused to each TGB coding sequence within the viral genome. Confocal microscopy was used to study subcellular accumulation of each protein in virus-infected plants and protoplasts. GFP:TGBp2 and TGBp3:GFP were both seen in the ER, ER-associated granular vesicles, and perinuclear X-bodies suggesting that these proteins interact in the same subdomains of the endomembrane network. When plasmids expressing CFP:TGBp2 and TGBp3:GFP were co-delivered to tobacco leaf epidermal cells, the fluorescent signals overlapped in ER-associated granular vesicles indicating that these proteins colocalize in this subcellular compartment. GFP:TGBp1 was seen in the nucleus, cytoplasm, rod-like inclusion bodies, and in punctate sites embedded in the cell wall. The puncta were reminiscent of previous reports showing viral proteins in plasmodesmata. Experiments using CFP:TGBp1 and YFP:TGBp2 or TGBp3:GFP showed CFP:TGBp1 remained in the cytoplasm surrounding the endomembrane network. There was no evidence that the granular vesicles contained TGBp1. Yeast two hybrid experiments showed TGBp1 self associates but failed to detect interactions between TGBp1 and TGBp2 or TGBp3. These experiments indicate that the PVX TGB proteins have complex subcellular accumulation patterns and likely cooperate across subcellular compartments to promote virus infection.
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Affiliation(s)
- Timmy D Samuels
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
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