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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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Xue M, Arvy N, German‐Retana S. The mystery remains: How do potyviruses move within and between cells? MOLECULAR PLANT PATHOLOGY 2023; 24:1560-1574. [PMID: 37571979 PMCID: PMC10632792 DOI: 10.1111/mpp.13383] [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: 05/25/2023] [Revised: 07/06/2023] [Accepted: 07/25/2023] [Indexed: 08/13/2023]
Abstract
The genus Potyvirus is considered as the largest among plant single-stranded (positive-sense) RNA viruses, causing considerable economic damage to vegetable and fruit crops worldwide. Through the coordinated action of four viral proteins and a few identified host factors, potyviruses exploit the endomembrane system of infected cells for their replication and for their intra- and intercellular movement to and through plasmodesmata (PDs). Although a significant amount of data concerning potyvirus movement has been published, no synthetic review compiling and integrating all information relevant to our current understanding of potyvirus transport is available. In this review, we highlight the complexity of potyvirus movement pathways and present three potential nonexclusive mechanisms based on (1) the use of the host endomembrane system to produce membranous replication vesicles that are targeted to PDs and move from cell to cell, (2) the movement of extracellular viral vesicles in the apoplasm, and (3) the transport of virion particles or ribonucleoprotein complexes through PDs. We also present and discuss experimental data supporting these different models as well as the aspects that still remain mostly speculative.
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Affiliation(s)
- Mingshuo Xue
- Univ. Bordeaux, INRAE, UMR 1332 Biologie du fruit et PathologieVillenave d'Ornon CedexFrance
| | - Nathalie Arvy
- Univ. Bordeaux, INRAE, UMR 1332 Biologie du fruit et PathologieVillenave d'Ornon CedexFrance
| | - Sylvie German‐Retana
- Univ. Bordeaux, INRAE, UMR 1332 Biologie du fruit et PathologieVillenave d'Ornon CedexFrance
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3
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Hu T, Guo D, Li B, Wang L, Liu H, Yin J, Jin T, Luan H, Sun L, Liu M, Zhi H, Li K. Soybean 40S Ribosomal Protein S8 (GmRPS8) Interacts with 6K1 Protein and Contributes to Soybean Susceptibility to Soybean Mosaic Virus. Viruses 2023; 15:2362. [PMID: 38140603 PMCID: PMC10748009 DOI: 10.3390/v15122362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 11/28/2023] [Accepted: 11/28/2023] [Indexed: 12/24/2023] Open
Abstract
Soybean mosaic virus (SMV), a member of Potyvirus, is the most destructive and widespread viral disease in soybean production. Our earlier studies identified a soybean 40S ribosomal protein S8 (GmRPS8) using the 6K1 protein of SMV as the bait to screen a soybean cDNA library. The present study aims to identify the interactions between GmRPS8 and SMV and characterize the role of GmRPS8 in SMV infection in soybean. Expression analysis showed higher SMV-induced GmRPS8 expression levels in a susceptible soybean cultivar when compared with a resistant cultivar, suggesting that GmRPS8 was involved in the response to SMV in soybean. Subcellular localization showed that GmRPS8 was localized in the nucleus. Moreover, the yeast two-hybrid (Y2H) experiments showed that GmRPS8 only interacted with 6K1 among the eleven proteins encoded by SMV. The interaction between GmRPS8 and 6K1 was further verified by a bimolecular fluorescence complementation (BiFC) assay, and the interaction was localized in the nucleus. Furthermore, knockdown of GmRPS8 by a virus-induced gene silencing (VIGS) system retarded the growth and development of soybeans and inhibited the accumulation of SMV in soybeans. Together, these results showed that GmRPS8 interacts with 6K1 and contributes to soybean susceptibility to SMV. Our findings provide new insights for understanding the role of GmRPS8 in the SMV infection cycle, which could help reveal potyviral replication mechanisms.
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Affiliation(s)
- Ting Hu
- Key Laboratory of Biology and Genetics Improvement of Soybean, Ministry of Agriculture/Zhongshan Biological Breeding Laboratory (ZSBBL)/National Innovation Platform for Soybean Breeding and Industry-Education Integration/State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization/College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China; (T.H.); (B.L.); (L.W.); (H.L.); (J.Y.); (T.J.); (L.S.); (M.L.)
| | - Dongquan Guo
- Jilin Academy of Agricultural Sciences, Changchun 130033, China;
| | - Bowen Li
- Key Laboratory of Biology and Genetics Improvement of Soybean, Ministry of Agriculture/Zhongshan Biological Breeding Laboratory (ZSBBL)/National Innovation Platform for Soybean Breeding and Industry-Education Integration/State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization/College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China; (T.H.); (B.L.); (L.W.); (H.L.); (J.Y.); (T.J.); (L.S.); (M.L.)
| | - Liqun Wang
- Key Laboratory of Biology and Genetics Improvement of Soybean, Ministry of Agriculture/Zhongshan Biological Breeding Laboratory (ZSBBL)/National Innovation Platform for Soybean Breeding and Industry-Education Integration/State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization/College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China; (T.H.); (B.L.); (L.W.); (H.L.); (J.Y.); (T.J.); (L.S.); (M.L.)
| | - Hui Liu
- Key Laboratory of Biology and Genetics Improvement of Soybean, Ministry of Agriculture/Zhongshan Biological Breeding Laboratory (ZSBBL)/National Innovation Platform for Soybean Breeding and Industry-Education Integration/State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization/College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China; (T.H.); (B.L.); (L.W.); (H.L.); (J.Y.); (T.J.); (L.S.); (M.L.)
| | - Jinlong Yin
- Key Laboratory of Biology and Genetics Improvement of Soybean, Ministry of Agriculture/Zhongshan Biological Breeding Laboratory (ZSBBL)/National Innovation Platform for Soybean Breeding and Industry-Education Integration/State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization/College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China; (T.H.); (B.L.); (L.W.); (H.L.); (J.Y.); (T.J.); (L.S.); (M.L.)
| | - Tongtong Jin
- Key Laboratory of Biology and Genetics Improvement of Soybean, Ministry of Agriculture/Zhongshan Biological Breeding Laboratory (ZSBBL)/National Innovation Platform for Soybean Breeding and Industry-Education Integration/State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization/College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China; (T.H.); (B.L.); (L.W.); (H.L.); (J.Y.); (T.J.); (L.S.); (M.L.)
| | - Hexiang Luan
- Institute of Plant Genetic Engineering, College of Life Science, Qingdao Agricultural University, Qingdao 266109, China;
| | - Lei Sun
- Key Laboratory of Biology and Genetics Improvement of Soybean, Ministry of Agriculture/Zhongshan Biological Breeding Laboratory (ZSBBL)/National Innovation Platform for Soybean Breeding and Industry-Education Integration/State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization/College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China; (T.H.); (B.L.); (L.W.); (H.L.); (J.Y.); (T.J.); (L.S.); (M.L.)
| | - Mengzhuo Liu
- Key Laboratory of Biology and Genetics Improvement of Soybean, Ministry of Agriculture/Zhongshan Biological Breeding Laboratory (ZSBBL)/National Innovation Platform for Soybean Breeding and Industry-Education Integration/State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization/College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China; (T.H.); (B.L.); (L.W.); (H.L.); (J.Y.); (T.J.); (L.S.); (M.L.)
| | - Haijian Zhi
- Key Laboratory of Biology and Genetics Improvement of Soybean, Ministry of Agriculture/Zhongshan Biological Breeding Laboratory (ZSBBL)/National Innovation Platform for Soybean Breeding and Industry-Education Integration/State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization/College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China; (T.H.); (B.L.); (L.W.); (H.L.); (J.Y.); (T.J.); (L.S.); (M.L.)
| | - Kai Li
- Key Laboratory of Biology and Genetics Improvement of Soybean, Ministry of Agriculture/Zhongshan Biological Breeding Laboratory (ZSBBL)/National Innovation Platform for Soybean Breeding and Industry-Education Integration/State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization/College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China; (T.H.); (B.L.); (L.W.); (H.L.); (J.Y.); (T.J.); (L.S.); (M.L.)
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Mäkinen K, Aspelin W, Pollari M, Wang L. How do they do it? The infection biology of potyviruses. Adv Virus Res 2023; 117:1-79. [PMID: 37832990 DOI: 10.1016/bs.aivir.2023.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2023]
Affiliation(s)
- Kristiina Mäkinen
- Department of Agricultural Sciences, Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland.
| | - William Aspelin
- Department of Agricultural Sciences, Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland
| | - Maija Pollari
- Department of Agricultural Sciences, Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland
| | - Linping Wang
- Department of Agricultural Sciences, Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland
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Lee YR, Siddique MI, Kim DS, Lee ES, Han K, Kim SG, Lee HE. CRISPR/Cas9-mediated gene editing to confer turnip mosaic virus (TuMV) resistance in Chinese cabbage ( Brassica rapa). HORTICULTURE RESEARCH 2023; 10:uhad078. [PMID: 37323233 PMCID: PMC10261878 DOI: 10.1093/hr/uhad078] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 04/10/2023] [Indexed: 06/17/2023]
Abstract
Genome editing approaches, particularly the CRISPR/Cas9 technology, are becoming state-of-the-art for trait development in numerous breeding programs. Significant advances in improving plant traits are enabled by this influential tool, especially for disease resistance, compared to traditional breeding. One of the potyviruses, the turnip mosaic virus (TuMV), is the most widespread and damaging virus that infects Brassica spp. worldwide. We generated the targeted mutation at the eIF(iso)4E gene in the TuMV-susceptible cultivar "Seoul" using CRISPR/Cas9 to develop TuMV-resistant Chinese cabbage. We detected several heritable indel mutations in the edited T0 plants and developed T1 through generational progression. It was indicated in the sequence analysis of the eIF(iso)4E-edited T1 plants that the mutations were transferred to succeeding generations. These edited T1 plants conferred resistance to TuMV. It was shown with ELISA analysis the lack of accumulation of viral particles. Furthermore, we found a strong negative correlation (r = -0.938) between TuMV resistance and the genome editing frequency of eIF(iso)4E. Consequently, it was revealed in this study that CRISPR/Cas9 technique can expedite the breeding process to improve traits in Chinese cabbage plants.
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Affiliation(s)
- Ye-Rin Lee
- Vegetable Research Division, National Institute of Horticultural and Herbal Science, Rural Development Administration, Wanju, 55365, Republic of Korea
| | - Muhammad Irfan Siddique
- Department of Horticultural Sciences, North Carolina State University Mountain Horticultural Crops Research, Extension Center 455 Research Drive, Mills River, NC 28759, USA
| | - Do-Sun Kim
- Vegetable Research Division, National Institute of Horticultural and Herbal Science, Rural Development Administration, Wanju, 55365, Republic of Korea
| | - Eun Su Lee
- Vegetable Research Division, National Institute of Horticultural and Herbal Science, Rural Development Administration, Wanju, 55365, Republic of Korea
| | - Koeun Han
- Vegetable Research Division, National Institute of Horticultural and Herbal Science, Rural Development Administration, Wanju, 55365, Republic of Korea
| | - Sang-Gyu Kim
- Department of Biological Sciences, Korea Advanced Institute for Science and Technology, Daejeon, 34141, Republic of Korea
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Soybean Mosaic Virus 6K1 Interactors Screening and GmPR4 and GmBI1 Function Characterization. Int J Mol Sci 2023; 24:ijms24065304. [PMID: 36982379 PMCID: PMC10049162 DOI: 10.3390/ijms24065304] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 02/27/2023] [Accepted: 03/04/2023] [Indexed: 03/12/2023] Open
Abstract
Host proteins are essential during virus infection, and viral factors must target numerous host factors to complete their infectious cycle. The mature 6K1 protein of potyviruses is required for viral replication in plants. However, the interaction between 6K1 and host factors is poorly understood. The present study aims to identify the host interacting proteins of 6K1. Here, the 6K1 of Soybean mosaic virus (SMV) was used as the bait to screen a soybean cDNA library to gain insights about the interaction between 6K1 and host proteins. One hundred and twenty-seven 6K1 interactors were preliminarily identified, and they were classified into six groups, including defense-related, transport-related, metabolism-related, DNA binding, unknown, and membrane-related proteins. Then, thirty-nine proteins were cloned and merged into a prey vector to verify the interaction with 6K1, and thirty-three of these proteins were confirmed to interact with 6K1 by yeast two-hybrid (Y2H) assay. Of the thirty-three proteins, soybean pathogenesis-related protein 4 (GmPR4) and Bax inhibitor 1 (GmBI1) were chosen for further study. Their interactions with 6K1 were also confirmed by bimolecular fluorescence complementation (BiFC) assay. Subcellular localization showed that GmPR4 was localized to the cytoplasm and endoplasmic reticulum (ER), and GmBI1 was located in the ER. Moreover, both GmPR4 and GmBI1 were induced by SMV infection, ethylene and ER stress. The transient overexpression of GmPR4 and GmBI1 reduced SMV accumulation in tobacco, suggesting their involvement in the resistance to SMV. These results would contribute to exploring the mode of action of 6K1 in viral replication and improve our knowledge of the role of PR4 and BI1 in SMV response.
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Zlobin N, Taranov V. Plant eIF4E isoforms as factors of susceptibility and resistance to potyviruses. FRONTIERS IN PLANT SCIENCE 2023; 14:1041868. [PMID: 36844044 PMCID: PMC9950400 DOI: 10.3389/fpls.2023.1041868] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Accepted: 01/30/2023] [Indexed: 06/18/2023]
Abstract
Potyviruses are the largest group of plant-infecting RNA viruses that affect a wide range of crop plants. Plant resistance genes against potyviruses are often recessive and encode translation initiation factors eIF4E. The inability of potyviruses to use plant eIF4E factors leads to the development of resistance through a loss-of-susceptibility mechanism. Plants have a small family of eIF4E genes that encode several isoforms with distinct but overlapping functions in cell metabolism. Potyviruses use distinct eIF4E isoforms as susceptibility factors in different plants. The role of different members of the plant eIF4E family in the interaction with a given potyvirus could differ drastically. An interplay exists between different members of the eIF4E family in the context of plant-potyvirus interactions, allowing different eIF4E isoforms to modulate each other's availability as susceptibility factors for the virus. In this review, possible molecular mechanisms underlying this interaction are discussed, and approaches to identify the eIF4E isoform that plays a major role in the plant-potyvirus interaction are suggested. The final section of the review discusses how knowledge about the interaction between different eIF4E isoforms can be used to develop plants with durable resistance to potyviruses.
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Ray S, Casteel CL. Effector-mediated plant-virus-vector interactions. THE PLANT CELL 2022; 34:1514-1531. [PMID: 35277714 PMCID: PMC9048964 DOI: 10.1093/plcell/koac058] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 02/14/2022] [Indexed: 05/30/2023]
Abstract
Hemipterans (such as aphids, whiteflies, and leafhoppers) are some of the most devastating insect pests due to the numerous plant pathogens they transmit as vectors, which are primarily viral. Over the past decade, tremendous progress has been made in broadening our understanding of plant-virus-vector interactions, yet on the molecular level, viruses and vectors have typically been studied in isolation of each other until recently. From that work, it is clear that both hemipteran vectors and viruses use effectors to manipulate host physiology and successfully colonize a plant and that co-evolutionary dynamics have resulted in effective host immune responses, as well as diverse mechanisms of counterattack by both challengers. In this review, we focus on advances in effector-mediated plant-virus-vector interactions and the underlying mechanisms. We propose that molecular synergisms in vector-virus interactions occur in cases where both the virus and vector benefit from the interaction (mutualism). To support this view, we show that mutualisms are common in virus-vector interactions and that virus and vector effectors target conserved mechanisms of plant immunity, including plant transcription factors, and plant protein degradation pathways. Finally, we outline ways to identify true effector synergisms in the future and propose future research directions concerning the roles effectors play in plant-virus-vector interactions.
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Affiliation(s)
- Swayamjit Ray
- School of Integrative Plant Science, Plant Pathology and Plant-Microbe Biology Section, Cornell University, Ithaca, New York 14850, USA
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Rocher M, Simon V, Jolivet MD, Sofer L, Deroubaix AF, Germain V, Mongrand S, German-Retana S. StREM1.3 REMORIN Protein Plays an Agonistic Role in Potyvirus Cell-to-Cell Movement in N. benthamiana. Viruses 2022; 14:574. [PMID: 35336981 PMCID: PMC8951588 DOI: 10.3390/v14030574] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 03/10/2022] [Accepted: 03/10/2022] [Indexed: 02/04/2023] Open
Abstract
REMORIN proteins belong to a plant-specific multigene family that localise in plasma membrane nanodomains and in plasmodesmata. We previously showed that in Nicotiana benthamiana, group 1 StREM1.3 limits the cell-to-cell spread of a potexvirus without affecting viral replication. This prompted us to check whether an effect on viral propagation could apply to potyvirus species Turnip mosaic virus (TuMV) and Potato virus A (PVA). Our results show that StREM1.3 transient or stable overexpression in transgenic lines increases potyvirus propagation, while it is slowed down in transgenic lines underexpressing endogenous NbREMs, without affecting viral replication. TuMV and PVA infection do not alter the membranous localisation of StREM1.3. Furthermore, StREM1.3-membrane anchoring is necessary for its agonist effect on potyvirus propagation. StREM1.3 phosphocode seems to lead to distinct plant responses against potexvirus and potyvirus. We also showed that StREM1.3 interacts in yeast and in planta with the key potyviral movement protein CI (cylindrical inclusion) at the level of the plasma membrane but only partially at plasmodesmata pit fields. TuMV infection also counteracts StREM1.3-induced plasmodesmata callose accumulation at plasmodesmata. Altogether, these results showed that StREM1.3 plays an agonistic role in potyvirus cell-to-cell movement in N. benthamiana.
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Affiliation(s)
- Marion Rocher
- Laboratoire de Biogenèse Membranaire, UMR 5200, CNRS Université Bordeaux, 71 Av. E. Bourlaux, 33140 Villenave d’Ornon, France; (M.R.); (M.-D.J.); (A.-F.D.); (V.G.); (S.M.)
| | - Vincent Simon
- UMR 1332 Biologie du Fruit et Pathologie, INRAE Université Bordeaux, 71 Av. E. Bourlaux, CS20032, CEDEX, 33882 Villenave d’Ornon, France; (V.S.); (L.S.)
| | - Marie-Dominique Jolivet
- Laboratoire de Biogenèse Membranaire, UMR 5200, CNRS Université Bordeaux, 71 Av. E. Bourlaux, 33140 Villenave d’Ornon, France; (M.R.); (M.-D.J.); (A.-F.D.); (V.G.); (S.M.)
| | - Luc Sofer
- UMR 1332 Biologie du Fruit et Pathologie, INRAE Université Bordeaux, 71 Av. E. Bourlaux, CS20032, CEDEX, 33882 Villenave d’Ornon, France; (V.S.); (L.S.)
| | - Anne-Flore Deroubaix
- Laboratoire de Biogenèse Membranaire, UMR 5200, CNRS Université Bordeaux, 71 Av. E. Bourlaux, 33140 Villenave d’Ornon, France; (M.R.); (M.-D.J.); (A.-F.D.); (V.G.); (S.M.)
| | - Véronique Germain
- Laboratoire de Biogenèse Membranaire, UMR 5200, CNRS Université Bordeaux, 71 Av. E. Bourlaux, 33140 Villenave d’Ornon, France; (M.R.); (M.-D.J.); (A.-F.D.); (V.G.); (S.M.)
| | - Sébastien Mongrand
- Laboratoire de Biogenèse Membranaire, UMR 5200, CNRS Université Bordeaux, 71 Av. E. Bourlaux, 33140 Villenave d’Ornon, France; (M.R.); (M.-D.J.); (A.-F.D.); (V.G.); (S.M.)
| | - Sylvie German-Retana
- UMR 1332 Biologie du Fruit et Pathologie, INRAE Université Bordeaux, 71 Av. E. Bourlaux, CS20032, CEDEX, 33882 Villenave d’Ornon, France; (V.S.); (L.S.)
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Abstract
The NIa protease of potyviruses is a chymotrypsin-like cysteine protease related to the picornavirus 3C protease. It is also a multifunctional protein known to play multiple roles during virus infection. Picornavirus 3C proteases cleave hundreds of host proteins to facilitate virus infection. However, whether or not potyvirus NIa proteases cleave plant proteins has so far not been tested. Regular expression search using the cleavage site consensus sequence [EQN]xVxH[QE]/[SGTA] for the plum pox virus (PPV) protease identified 90 to 94 putative cleavage events in the proteomes of Prunus persica (a crop severely affected by PPV), Arabidopsis thaliana, and Nicotiana benthamiana (two experimental hosts). In vitro processing assays confirmed cleavage of six A. thaliana and five P. persica proteins by the PPV protease. These proteins were also cleaved in vitro by the protease of turnip mosaic virus (TuMV), which has a similar specificity. We confirmed in vivo cleavage of a transiently expressed tagged version of AtEML2, an EMSY-like protein belonging to a family of nuclear histone readers known to be involved in pathogen resistance. Cleavage of AtEML2 was efficient and was observed in plants that coexpressed the PPV or TuMV NIa proteases or in plants that were infected with TuMV. We also showed partial in vivo cleavage of AtDUF707, a membrane protein annotated as lysine ketoglutarate reductase trans-splicing protein. Although cleavage of the corresponding endogenous plant proteins remains to be confirmed, the results show that a plant virus protease can cleave host proteins during virus infection and highlight a new layer of plant-virus interactions. IMPORTANCE Viruses are highly adaptive and use multiple molecular mechanisms to highjack or modify the cellular resources to their advantage. They must also counteract or evade host defense responses. One well-characterized mechanism used by vertebrate viruses is the proteolytic cleavage of host proteins to inhibit the activities of these proteins and/or to produce cleaved protein fragments that are beneficial to the virus infection cycle. Even though almost half of the known plant viruses encode at least one protease, it was not known whether plant viruses employ this strategy. Using an in silico prediction approach and the well-characterized specificity of potyvirus NIa proteases, we were able to identify hundreds of putative cleavage sites in plant proteins, several of which were validated by downstream experiments. It can be anticipated that many other plant virus proteases also cleave host proteins and that the identification of these cleavage events will lead to novel antiviral strategies.
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Eruera AR, McSweeney AM, McKenzie-Goldsmith GM, Ward VK. Protein Nucleotidylylation in +ssRNA Viruses. Viruses 2021; 13:1549. [PMID: 34452414 PMCID: PMC8402628 DOI: 10.3390/v13081549] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/30/2021] [Accepted: 08/02/2021] [Indexed: 12/22/2022] Open
Abstract
Nucleotidylylation is a post-transcriptional modification important for replication in the picornavirus supergroup of RNA viruses, including members of the Caliciviridae, Coronaviridae, Picornaviridae and Potyviridae virus families. This modification occurs when the RNA-dependent RNA polymerase (RdRp) attaches one or more nucleotides to a target protein through a nucleotidyl-transferase reaction. The most characterized nucleotidylylation target is VPg (viral protein genome-linked), a protein linked to the 5' end of the genome in Caliciviridae, Picornaviridae and Potyviridae. The nucleotidylylation of VPg by RdRp is a critical step for the VPg protein to act as a primer for genome replication and, in Caliciviridae and Potyviridae, for the initiation of translation. In contrast, Coronaviridae do not express a VPg protein, but the nucleotidylylation of proteins involved in replication initiation is critical for genome replication. Furthermore, the RdRp proteins of the viruses that perform nucleotidylylation are themselves nucleotidylylated, and in the case of coronavirus, this has been shown to be essential for viral replication. This review focuses on nucleotidylylation within the picornavirus supergroup of viruses, including the proteins that are modified, what is known about the nucleotidylylation process and the roles that these modifications have in the viral life cycle.
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Affiliation(s)
| | | | | | - Vernon K. Ward
- Department of Microbiology & Immunology, School of Biomedical Sciences, University of Otago, PO Box 56, Dunedin 9054, New Zealand; (A.-R.E.); (A.M.M.); (G.M.M.-G.)
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Zhang X, Wang X, Xu K, Jiang Z, Dong K, Xie X, Zhang H, Yue N, Zhang Y, Wang XB, Han C, Yu J, Li D. The serine/threonine/tyrosine kinase STY46 defends against hordeivirus infection by phosphorylating γb protein. PLANT PHYSIOLOGY 2021; 186:715-730. [PMID: 33576790 PMCID: PMC8154058 DOI: 10.1093/plphys/kiab056] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 01/21/2021] [Indexed: 05/05/2023]
Abstract
Protein phosphorylation is a common post-translational modification that frequently occurs during plant-virus interaction. Host protein kinases often regulate virus infectivity and pathogenicity by phosphorylating viral proteins. The Barley stripe mosaic virus (BSMV) γb protein plays versatile roles in virus infection and the coevolutionary arms race between plant defense and viral counter-defense. Here, we identified that the autophosphorylated cytosolic serine/threonine/tyrosine (STY) protein kinase 46 of Nicotiana benthamiana (NbSTY46) phosphorylates and directly interacts with the basic motif domain (aa 19-47) of γb in vitro and in vivo. Overexpression of wild-type NbSTY46, either transiently or transgenically, suppresses BSMV replication and ameliorates viral symptoms, whereas silencing of NbSTY46 leads to increased viral replication and exacerbated symptom. Moreover, the antiviral role of NbSTY46 requires its kinase activity, as the NbSTY46T436A mutant, lacking kinase activity, not only loses the ability to phosphorylate and interact with γb but also fails to impair BSMV infection when expressed in plants. NbSTY46 could also inhibit the replication of Lychnis ringspot virus, another chloroplast-replicating hordeivirus. In summary, we report a function of the cytosolic kinase STY46 in defending against plant viral infection by phosphorylating a viral protein in addition to its basal function in plant growth, development, and abiotic stress responses.
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Affiliation(s)
- Xuan Zhang
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xueting Wang
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Kai Xu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing 210046, China
| | - Zhihao Jiang
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Kai Dong
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Xialin Xie
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - He Zhang
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Ning Yue
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Yongliang Zhang
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Xian-Bing Wang
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Chenggui Han
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Jialin Yu
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Dawei Li
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
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Xie J, Jiang T, Li Z, Li X, Fan Z, Zhou T. Sugarcane mosaic virus remodels multiple intracellular organelles to form genomic RNA replication sites. Arch Virol 2021; 166:1921-1930. [PMID: 33905022 DOI: 10.1007/s00705-021-05077-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Accepted: 03/12/2021] [Indexed: 12/28/2022]
Abstract
Positive-stranded RNA viruses usually remodel the host endomembrane system to form virus-induced intracellular vesicles for replication during infections. The genus Potyvirus of the family Potyviridae represents the largest number of positive single-stranded RNA viruses, and its members cause great damage to crop production worldwide. Although potyviruses have a wide host range, each potyvirus infects a relatively limited number of host species. Phylogenesis and host range analysis can divide potyviruses into monocot-infecting and dicot-infecting groups, suggesting that they differ in their infection mechanisms, probably during replication. Comprehensive studies on the model dicot-infecting turnip mosaic virus have shown that the 6K2-induced replication vesicles are derived from the endoplasmic reticulum (ER) and subsequently target chloroplasts for viral genome replication. However, the replication site of monocot-infecting potyviruses is unknown. In this study, we show that the precursor 6K2-VPg-Pro polyproteins of dicot-infecting potyviruses and monocot-infecting potyviruses cluster phylogenetically in two separate groups. With a typical gramineae-infecting potyvirus-sugarcane mosaic virus (SCMV)-we found that replicative double-stranded RNA (dsRNA) forms aggregates in the cytoplasm but does not associate with chloroplasts. SCMV 6K2-VPg-Pro-induced vesicles colocalize with replicative dsRNA. Moreover, SCMV 6K2-VPg-Pro-induced structures target multiple intracellular organelles, including the ER, Golgi apparatus, mitochondria, and peroxisomes, and have no evident association with chloroplasts.
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Affiliation(s)
- Jipeng Xie
- State Key Laboratory for Agro-Biotechnology, and Ministry of Agriculture and Rural Affairs, Key Laboratory for Pest Monitoring and Green Management, Department of Plant Pathology, China Agricultural University, Beijing, 100193, China
| | - Tong Jiang
- State Key Laboratory for Agro-Biotechnology, and Ministry of Agriculture and Rural Affairs, Key Laboratory for Pest Monitoring and Green Management, Department of Plant Pathology, China Agricultural University, Beijing, 100193, China
| | - Zhifang Li
- State Key Laboratory for Agro-Biotechnology, and Ministry of Agriculture and Rural Affairs, Key Laboratory for Pest Monitoring and Green Management, Department of Plant Pathology, China Agricultural University, Beijing, 100193, China
| | - Xiangdong Li
- Department of Plant Pathology, Shandong Agricultural University, Tai'an, 271018, China
| | - Zaifeng Fan
- State Key Laboratory for Agro-Biotechnology, and Ministry of Agriculture and Rural Affairs, Key Laboratory for Pest Monitoring and Green Management, Department of Plant Pathology, China Agricultural University, Beijing, 100193, China
| | - Tao Zhou
- State Key Laboratory for Agro-Biotechnology, and Ministry of Agriculture and Rural Affairs, Key Laboratory for Pest Monitoring and Green Management, Department of Plant Pathology, China Agricultural University, Beijing, 100193, China.
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Changes in Subcellular Localization of Host Proteins Induced by Plant Viruses. Viruses 2021; 13:v13040677. [PMID: 33920930 PMCID: PMC8071230 DOI: 10.3390/v13040677] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 04/08/2021] [Accepted: 04/12/2021] [Indexed: 12/24/2022] Open
Abstract
Viruses are dependent on host factors at all parts of the infection cycle, such as translation, genome replication, encapsidation, and cell-to-cell and systemic movement. RNA viruses replicate their genome in compartments associated with the endoplasmic reticulum, chloroplasts, and mitochondria or peroxisome membranes. In contrast, DNA viruses replicate in the nucleus. Viral infection causes changes in plant gene expression and in the subcellular localization of some host proteins. These changes may support or inhibit virus accumulation and spread. Here, we review host proteins that change their subcellular localization in the presence of a plant virus. The most frequent change is the movement of host cytoplasmic proteins into the sites of virus replication through interactions with viral proteins, and the protein contributes to essential viral processes. In contrast, only a small number of studies document changes in the subcellular localization of proteins with antiviral activity. Understanding the changes in the subcellular localization of host proteins during plant virus infection provides novel insights into the mechanisms of plant–virus interactions and may help the identification of targets for designing genetic resistance to plant viruses.
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Li Q, Liu N, Liu Q, Zheng X, Lu L, Gao W, Liu Y, Liu Y, Zhang S, Wang Q, Pan J, Chen C, Mi Y, Yang M, Cheng X, Ren G, Yuan YW, Zhang X. DEAD-box helicases modulate dicing body formation in Arabidopsis. SCIENCE ADVANCES 2021; 7:7/18/eabc6266. [PMID: 33910901 PMCID: PMC8081359 DOI: 10.1126/sciadv.abc6266] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 03/10/2021] [Indexed: 05/02/2023]
Abstract
Eukaryotic cells contain numerous membraneless organelles that are made from liquid droplets of proteins and nucleic acids and that provide spatiotemporal control of various cellular processes. However, the molecular mechanisms underlying the formation and rapid stress-induced alterations of these organelles are relatively uncharacterized. Here, we investigated the roles of DEAD-box helicases in the formation and alteration of membraneless nuclear dicing bodies (D-bodies) in Arabidopsis thaliana We uncovered that RNA helicase 6 (RH6), RH8, and RH12 are previously unidentified D-body components. These helicases interact with and promote the phase separation of SERRATE, a key component of D-bodies, and drive the formation of D-bodies through liquid-liquid phase separations (LLPSs). The accumulation of these helicases in the nuclei decreases upon Turnip mosaic virus infections, which couples with the decrease of D-bodies. Our results thus reveal the key roles of RH6, RH8, and RH12 in modulating D-body formation via LLPSs.
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Affiliation(s)
- Qi Li
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Ningkun Liu
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qing Liu
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xingguo Zheng
- Donald Danforth Plant Science Center, St. Louis, MO 63132, USA
| | - Lu Lu
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Wenrui Gao
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yang Liu
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yan Liu
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shicheng Zhang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Qian Wang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jing Pan
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Chen Chen
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yingjie Mi
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- Department of Life Sciences, Henan Normal University, Xinxiang, Henan 453007, China
| | - Meiling Yang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xiaofei Cheng
- Key Laboratory of Germplasm Enhancement, Physiology and Ecology of Food Crops in Cold Region of Chinese Education Ministry, College of Agriculture, Northeast Agricultural University, Harbin 150030, China
| | - Guodong Ren
- State Key Laboratory of Genetic Engineering and Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Yao-Wu Yuan
- Department of Ecology and Evolutionary Biology, University of Connecticut, 75 North Eagleville Road, Unit 3043, Storrs, CT 06269, USA
| | - Xiaoming Zhang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, China
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Freire MÁ. Viral silencing suppressors and cellular proteins partner with plant RRP6-like exoribonucleases. Virus Genes 2020; 56:621-631. [PMID: 32519287 DOI: 10.1007/s11262-020-01775-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 06/02/2020] [Indexed: 10/24/2022]
Abstract
RNA silencing and RNA decay are functionally interlaced, regulate gene expression and play a pivotal role in antiviral responses. As a counter-defensive strategy, many plant and mammalian viruses encode suppressors which interfere with both mechanisms. However, the protein interactions that connect these pathways remain elusive. Previous work reported that RNA silencing suppressors from different potyviruses, together with translation initiation factors EIF(iso)4E, interacted with the C-terminal region of the tobacco exoribonuclease RRP6-like 2, a component of the RNA decay exosome complex. Here, we investigate whether other viral silencing suppressors and cellular proteins might also bind RRP6-like exoribonucleases. A candidate search approach based on yeast two-hybrid protein interaction assays showed that three other unrelated viral suppressors, two from plant viruses and one from a mammalian virus, bound the C-terminus of the tobacco RRP6-like 2, the full-length of the Arabidopsis RRP6L1 protein and its C-terminal region. In addition, RRP6-like proteins were found to interact with members of the cellular double-stranded RNA-binding protein (DRB) family involved in RNA silencing. The C-terminal regions of RRP6L proteins are engaged in homotypic and heterotypic interactions and were predicted to be disordered. Collectively, these results suggest a protein interaction network that connects components of RNA decay and RNA silencing that is targeted by viral silencing suppressors.
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Affiliation(s)
- Miguel Ángel Freire
- Instituto Multidisciplinario de Biología Vegetal (IMBIV), CONICET, Universidad Nacional de Córdoba (UNC), Av. Vélez Sarsfield 299, CC 495, 5000, Córdoba, Argentina.
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Rajamäki ML, Sikorskaite-Gudziuniene S, Sarmah N, Varjosalo M, Valkonen JPT. Nuclear proteome of virus-infected and healthy potato leaves. BMC PLANT BIOLOGY 2020; 20:355. [PMID: 32727361 PMCID: PMC7392702 DOI: 10.1186/s12870-020-02561-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 07/20/2020] [Indexed: 05/30/2023]
Abstract
BACKGROUND Infection of plants by viruses interferes with expression and subcellular localization of plant proteins. Potyviruses comprise the largest and most economically damaging group of plant-infecting RNA viruses. In virus-infected cells, at least two potyviral proteins localize to nucleus but reasons remain partly unknown. RESULTS In this study, we examined changes in the nuclear proteome of leaf cells from a diploid potato line (Solanum tuberosum L.) after infection with potato virus A (PVA; genus Potyvirus; Potyviridae) and compared the data with that acquired for healthy leaves. Gel-free liquid chromatography-coupled to tandem mass spectrometry was used to identify 807 nuclear proteins in the potato line v2-108; of these proteins, 370 were detected in at least two samples of healthy leaves. A total of 313 proteins were common in at least two samples of healthy and PVA-infected leaves; of these proteins, 8 showed differential accumulation. Sixteen proteins were detected exclusively in the samples from PVA-infected leaves, whereas other 16 proteins were unique to healthy leaves. The protein Dnajc14 was only detected in healthy leaves, whereas different ribosomal proteins, ribosome-biogenesis proteins, and RNA splicing-related proteins were over-represented in the nuclei of PVA-infected leaves. Two virus-encoded proteins were identified in the samples of PVA-infected leaves. CONCLUSIONS Our results show that PVA infection alters especially ribosomes and splicing-related proteins in the nucleus of potato leaves. The data increase our understanding of potyvirus infection and the role of nucleus in infection. To our knowledge, this is the first study of the nuclear proteome of potato leaves and one of the few studies of changes occurring in nuclear proteomes in response to plant virus infection.
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Affiliation(s)
- Minna-Liisa Rajamäki
- Department of Agricultural Sciences, University of Helsinki, PO Box 27, FI-00014, Helsinki, Finland.
| | - Sidona Sikorskaite-Gudziuniene
- Department of Agricultural Sciences, University of Helsinki, PO Box 27, FI-00014, Helsinki, Finland
- Institute of Horticulture, Lithuanian Research Centre for Agriculture and Forestry, Kaunas Street 30, Babtai, LT-54333, Kaunas District, Lithuania
| | - Nandita Sarmah
- Department of Agricultural Sciences, University of Helsinki, PO Box 27, FI-00014, Helsinki, Finland
| | - Markku Varjosalo
- Institute of Biotechnology, University of Helsinki, PO Box 56, FI-00014, Helsinki, Finland
| | - Jari P T Valkonen
- Department of Agricultural Sciences, University of Helsinki, PO Box 27, FI-00014, Helsinki, Finland
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Lv H, Fang Z, Yang L, Zhang Y, Wang Y. An update on the arsenal: mining resistance genes for disease management of Brassica crops in the genomic era. HORTICULTURE RESEARCH 2020; 7:34. [PMID: 32194970 PMCID: PMC7072071 DOI: 10.1038/s41438-020-0257-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 01/12/2020] [Accepted: 01/15/2020] [Indexed: 05/18/2023]
Abstract
Brassica species include many economically important crops that provide nutrition and health-promoting substances to humans worldwide. However, as with all crops, their production is constantly threatened by emerging viral, bacterial, and fungal diseases, whose incidence has increased in recent years. Traditional methods of control are often costly, present limited effectiveness, and cause environmental damage; instead, the ideal approach is to mine and utilize the resistance genes of the Brassica crop hosts themselves. Fortunately, the development of genomics, molecular genetics, and biological techniques enables us to rapidly discover and apply resistance (R) genes. Herein, the R genes identified in Brassica crops are summarized, including their mapping and cloning, possible molecular mechanisms, and application in resistance breeding. Future perspectives concerning how to accurately discover additional R gene resources and efficiently utilize these genes in the genomic era are also discussed.
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Affiliation(s)
- Honghao Lv
- Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops, Ministry of Agriculture, 12# Zhongguancun South Street, Beijing, 100081 China
| | - Zhiyuan Fang
- Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops, Ministry of Agriculture, 12# Zhongguancun South Street, Beijing, 100081 China
| | - Limei Yang
- Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops, Ministry of Agriculture, 12# Zhongguancun South Street, Beijing, 100081 China
| | - Yangyong Zhang
- Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops, Ministry of Agriculture, 12# Zhongguancun South Street, Beijing, 100081 China
| | - Yong Wang
- Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops, Ministry of Agriculture, 12# Zhongguancun South Street, Beijing, 100081 China
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The RNA-Dependent RNA Polymerase NIb of Potyviruses Plays Multifunctional, Contrasting Roles during Viral Infection. Viruses 2020; 12:v12010077. [PMID: 31936267 PMCID: PMC7019339 DOI: 10.3390/v12010077] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 12/28/2019] [Accepted: 01/03/2020] [Indexed: 12/14/2022] Open
Abstract
Potyviruses represent the largest group of known plant RNA viruses and include many agriculturally important viruses, such as Plum pox virus, Soybean mosaic virus, Turnip mosaic virus, and Potato virus Y. Potyviruses adopt polyprotein processing as their genome expression strategy. Among the 11 known viral proteins, the nuclear inclusion protein b (NIb) is the RNA-dependent RNA polymerase responsible for viral genome replication. Beyond its principal role as an RNA replicase, NIb has been shown to play key roles in diverse virus–host interactions. NIb recruits several host proteins into the viral replication complexes (VRCs), which are essential for the formation of functional VRCs for virus multiplication, and interacts with the sumoylation pathway proteins to suppress NPR1-mediated immunity response. On the other hand, NIb serves as a target of selective autophagy as well as an elicitor of effector-triggered immunity, resulting in attenuated virus infection. These contrasting roles of NIb provide an excellent example of the complex co-evolutionary arms race between plant hosts and potyviruses. This review highlights the current knowledge about the multifunctional roles of NIb in potyvirus infection, and discusses future research directions.
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Xu M, Mazur MJ, Tao X, Kormelink R. Cellular RNA Hubs: Friends and Foes of Plant Viruses. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:40-54. [PMID: 31415225 DOI: 10.1094/mpmi-06-19-0161-fi] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
RNA granules are dynamic cellular foci that are widely spread in eukaryotic cells and play essential roles in cell growth and development, and immune and stress responses. Different types of granules can be distinguished, each with a specific function and playing a role in, for example, RNA transcription, modification, processing, decay, translation, and arrest. By means of communication and exchange of (shared) components, they form a large regulatory network in cells. Viruses have been reported to interact with one or more of these either cytoplasmic or nuclear granules, and act either proviral, to enable and support viral infection and facilitate viral movement, or antiviral, protecting or clearing hosts from viral infection. This review describes an overview and recent progress on cytoplasmic and nuclear RNA granules and their interplay with virus infection, first in animal systems and as a prelude to the status and current developments on plant viruses, which have been less well studied on this thus far.
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Affiliation(s)
- Min Xu
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
- Laboratory of Virology, Department of Plant Sciences, Wageningen University & Research, Droevendaalsesteeg 1, 6708PB Wageningen, The Netherlands
| | - Magdalena J Mazur
- Laboratory of Virology, Department of Plant Sciences, Wageningen University & Research, Droevendaalsesteeg 1, 6708PB Wageningen, The Netherlands
| | - Xiaorong Tao
- Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Richard Kormelink
- Laboratory of Virology, Department of Plant Sciences, Wageningen University & Research, Droevendaalsesteeg 1, 6708PB Wageningen, The Netherlands
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21
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[Recessive resistance to plant viruses by the deficiency of eukaryotic translation initiation factor genes.]. Uirusu 2020; 70:61-68. [PMID: 33967115 DOI: 10.2222/jsv.70.61] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Plant viruses, obligate parasitic pathogens, utilize a variety of host plant factors in the process of their infection due to the limited number of genes encoded in their own genomes. The genes encoding these host factors are called susceptibility genes because they are responsible for the susceptibility of plants to viruses. Plants lacking or having mutations in a susceptibility gene essential for the infection of a virus acquire resistance to the virus. Such resistance trait is called recessive resistance because of the recessive inherited characteristics. Recessive resistance is reported to account for about half of the plant viral resistance loci mapped in known cultivated crops. Eukaryotic translation initiation factor (eIF) 4E family genes are well-known susceptibility genes. Although there are many reports about eIF4E-mediated recessive resistance to plant viruses, the mechanistic insight of the resistance is still limited. Here we review focusing on studies that have elucidated the mechanism of eIF4E-mediated recessive resistance.
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22
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Ala-Poikela M, Rajamäki ML, Valkonen JP. A Novel Interaction Network Used by Potyviruses in Virus-Host Interactions at the Protein Level. Viruses 2019; 11:E1158. [PMID: 31847316 PMCID: PMC6950583 DOI: 10.3390/v11121158] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 12/10/2019] [Accepted: 12/11/2019] [Indexed: 12/30/2022] Open
Abstract
Host proteins that are central to infection of potyviruses (genus Potyvirus; family Potyviridae) include the eukaryotic translation initiation factors eIF4E and eIF(iso)4E. The potyviral genome-linked protein (VPg) and the helper component proteinase (HCpro) interact with each other and with eIF4E and eIF(iso)4E and proteins are involved in the same functions during viral infection. VPg interacts with eIF4E/eIF(iso)4E via the 7-methylguanosine cap-binding region, whereas HCpro interacts with eIF4E/eIF(iso)4E via the 4E-binding motif YXXXXLΦ, similar to the motif in eIF4G. In this study, HCpro and VPg were found to interact in the nucleus, nucleolus, and cytoplasm in cells infected with the potyvirus potato virus A (PVA). In the cytoplasm, interactions between HCpro and VPg occurred in punctate bodies not associated with viral replication vesicles. In addition to HCpro, the 4E-binding motif was recognized in VPg of PVA. Mutations in the 4E-binding motif of VPg from PVA weakened interactions with eIF4E and heavily reduced PVA virulence. Furthermore, mutations in the 4G-binding domain of eIF4E reduced interactions with VPg and abolished interactions with HCpro. Thus, HCpro and VPg can both interact with eIF4E using the 4E-binding motif. Our results suggest a novel interaction network used by potyviruses to interact with host plants via translation initiation factors.
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Affiliation(s)
| | - Minna-Liisa Rajamäki
- Department of Agricultural Sciences, University of Helsinki, P.O. Box 27, FI-00014 Helsinki, Finland;
| | - Jari P.T. Valkonen
- Department of Agricultural Sciences, University of Helsinki, P.O. Box 27, FI-00014 Helsinki, Finland;
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23
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Ishibashi K, Saruta M, Shimizu T, Shu M, Anai T, Komatsu K, Yamada N, Katayose Y, Ishikawa M, Ishimoto M, Kaga A. Soybean antiviral immunity conferred by dsRNase targets the viral replication complex. Nat Commun 2019; 10:4033. [PMID: 31562302 PMCID: PMC6764979 DOI: 10.1038/s41467-019-12052-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 08/13/2019] [Indexed: 11/08/2022] Open
Abstract
Eukaryotic positive-strand RNA viruses replicate their genomes in membranous compartments formed in a host cell, which sequesters the dsRNA replication intermediate from antiviral immune surveillance. Here, we find that soybean has developed a way to overcome this sequestration. We report the positional cloning of the broad-spectrum soybean mosaic virus resistance gene Rsv4, which encodes an RNase H family protein with dsRNA-degrading activity. An active-site mutant of Rsv4 is incapable of inhibiting virus multiplication and is associated with an active viral RNA polymerase complex in infected cells. These results suggest that Rsv4 enters the viral replication compartment and degrades viral dsRNA. Inspired by this model, we design three plant-gene-derived dsRNases that can inhibit the multiplication of the respective target viruses. These findings suggest a method for developing crops resistant to any target positive-strand RNA virus by fusion of endogenous host genes.
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Affiliation(s)
- Kazuhiro Ishibashi
- Plant and Microbial Research Unit, Division of Plant and Microbial Sciences, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, 2-1-2 Kannondai, Tsukuba, Ibaraki, 305-8602, Japan
| | - Masayasu Saruta
- Crop Breeding and Food Functional Components Division, Western Region Agricultural Research Center, National Agriculture and Food Research Organization, 1-3-1 Senyu-cho, Zentsuji-shi, Kagawa, 765-8508, Japan
- Soybean Breeding Unit, Institute of Crop Science, National Agriculture and Food Research Organization, 2-1-2 Kannondai, Tsukuba, Ibaraki, 305-8518, Japan
| | - Takehiko Shimizu
- Soybean and Field Crop Applied Genomics Research Unit, Institute of Crop Science, National Agriculture and Food Research Organization, 2-1-2 Kannondai, Tsukuba, Ibaraki, 305-8518, Japan
- Advanced Genomics Breeding Section, Institute of Crop Science, National Agriculture and Food Research Organization, 2-1-2 Kannondai, Tsukuba, Ibaraki, 305-8518, Japan
| | - Miao Shu
- Plant and Microbial Research Unit, Division of Plant and Microbial Sciences, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, 2-1-2 Kannondai, Tsukuba, Ibaraki, 305-8602, Japan
| | - Toyoaki Anai
- Faculty of Agriculture, Saga University, 1 Honjo-machi, Saga, 840-8502, Japan
| | - Kunihiko Komatsu
- Research Team for Crop Cold Tolerance, Hokkaido Agricultural Research Center, National Agriculture and Food Research Organization, Hitsujigaoka 1, Toyohira, Sapporo, Hokkaido, 062-8555, Japan
- Crop Breeding and Food Functional Components Division, Western Region Agricultural Research Center, National Agriculture and Food Research Organization, 1-3-1 Senyu-cho, Zentsuji-shi, Kagawa, 765-8508, Japan
| | - Naohiro Yamada
- Nagano Vegetable and Ornamental Crops Experiment Station, 1066-1, Soga, Shiojiri, Nagano, 399-6461, Japan
| | - Yuichi Katayose
- Advanced Genomics Breeding Section, Institute of Crop Science, National Agriculture and Food Research Organization, 1-2 Ohwashi, Tsukuba, Ibaraki, 305-8634, Japan
- Department of Planning and Coordination, National Agriculture and Food Research Organization, 3-1-1 Kannondai, Tsukuba, Ibaraki, 305-8517, Japan
| | - Masayuki Ishikawa
- Plant and Microbial Research Unit, Division of Plant and Microbial Sciences, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, 2-1-2 Kannondai, Tsukuba, Ibaraki, 305-8602, Japan
| | - Masao Ishimoto
- Soybean and Field Crop Applied Genomics Research Unit, Institute of Crop Science, National Agriculture and Food Research Organization, 2-1-2 Kannondai, Tsukuba, Ibaraki, 305-8518, Japan
- Division of Basic Research, Institute of Crop Science, National Agriculture and Food Research Organization, 3-1-1 Kannondai, Tsukuba, Ibaraki, 305-8517, Japan
| | - Akito Kaga
- Soybean and Field Crop Applied Genomics Research Unit, Institute of Crop Science, National Agriculture and Food Research Organization, 2-1-2 Kannondai, Tsukuba, Ibaraki, 305-8518, Japan.
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24
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Bruns AN, Li S, Mohannath G, Bisaro DM. Phosphorylation of Arabidopsis eIF4E and eIFiso4E by SnRK1 inhibits translation. FEBS J 2019; 286:3778-3796. [PMID: 31120171 DOI: 10.1111/febs.14935] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 03/28/2019] [Accepted: 05/21/2019] [Indexed: 01/01/2023]
Abstract
Regulation of protein synthesis is critical for maintaining cellular homeostasis. In mammalian systems, translational regulatory networks have been elucidated in considerable detail. In plants, however, regulation occurs through different mechanisms that remain largely elusive. In this study, we present evidence that the Arabidopsis thaliana energy sensing kinase SnRK1, a homologue of mammalian AMP-activated kinase and yeast sucrose non-fermenting 1 (SNF1), inhibits translation by phosphorylating the cap binding proteins eIF4E and eIFiso4E. We establish that eIF4E and eIFiso4E contain two deeply conserved SnRK1 consensus target sites and that both interact with SnRK1 in vivo. We then demonstrate that SnRK1 phosphorylation inhibits the ability of Arabidopsis eIF4E and eIFiso4E to complement a yeast strain lacking endogenous eIF4E, and that inhibition correlates with repression of polysome formation. Finally, we show that SnRK1 over-expression in Nicotiana benthamiana plants reduces polysome formation, and that this effect can be counteracted by transient expression of eIF4E or mutant eIF4E containing non-phosphorylatable SnRK1 target residues, but not by a phosphomimic eIF4E. Together, these studies elucidate a novel and direct pathway for translational control in plant cells. In light of previous findings that SnRK1 conditions an innate antiviral defense and is inhibited by geminivirus pathogenicity factors, we speculate that phosphorylation of cap binding proteins may be a component of the resistance mechanism.
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Affiliation(s)
- Aaron N Bruns
- Department of Molecular Genetics, Center for Applied Plant Sciences, Center for RNA Biology, and Infectious Diseases Institute, The Ohio State University, Columbus, OH, USA.,Ohio State Biochemistry Program, The Ohio State University, Columbus, OH, USA
| | - Sizhun Li
- Department of Molecular Genetics, Center for Applied Plant Sciences, Center for RNA Biology, and Infectious Diseases Institute, The Ohio State University, Columbus, OH, USA
| | - Gireesha Mohannath
- Department of Molecular Genetics, Center for Applied Plant Sciences, Center for RNA Biology, and Infectious Diseases Institute, The Ohio State University, Columbus, OH, USA
| | - David M Bisaro
- Department of Molecular Genetics, Center for Applied Plant Sciences, Center for RNA Biology, and Infectious Diseases Institute, The Ohio State University, Columbus, OH, USA.,Ohio State Biochemistry Program, The Ohio State University, Columbus, OH, USA
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25
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Richardson LGL. Hijacking the ER Membrane: Lessons from Turnip mosaic virus. PLANT PHYSIOLOGY 2019; 179:367-368. [PMID: 30709983 PMCID: PMC6426431 DOI: 10.1104/pp.18.01551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Affiliation(s)
- Lynn G L Richardson
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
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26
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Cabanillas DG, Jiang J, Movahed N, Germain H, Yamaji Y, Zheng H, Laliberté JF. Turnip Mosaic Virus Uses the SNARE Protein VTI11 in an Unconventional Route for Replication Vesicle Trafficking. THE PLANT CELL 2018; 30:2594-2615. [PMID: 30150314 PMCID: PMC6241277 DOI: 10.1105/tpc.18.00281] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 07/17/2018] [Accepted: 08/25/2018] [Indexed: 05/11/2023]
Abstract
Infection of plant cells by RNA viruses leads to the generation of organelle-like subcellular structures that contain the viral replication complex. During Turnip mosaic virus (TuMV) infection of Nicotiana benthamiana, the viral membrane protein 6K2 plays a key role in the release of motile replication vesicles from the host endoplasmic reticulum (ER). Here, we demonstrate that 6K2 contains a GxxxG motif within its predicted transmembrane domain that is vital for TuMV infection. Replacement of the Gly with Val within this motif inhibited virus production, and this was due to a relocation of the viral protein to the Golgi apparatus and the plasma membrane. This indicated that passage of 6K2 through the Golgi apparatus is a dead-end avenue for virus infection. Impairing the fusion of transport vesicles between the ER and the Golgi apparatus by overexpression of the SNARE Sec22 protein resulted in enhanced intercellular virus movement. Likewise, expression of nonfunctional, Golgi-located synaptotagmin during infection enhanced TuMV intercellular movement. 6K2 copurified with VTI11, a prevacuolar compartment SNARE protein. An Arabidopsis thaliana vti11 mutant was completely resistant to TuMV infection. We conclude that TuMV replication vesicles bypass the Golgi apparatus and take an unconventional pathway that may involve prevacuolar compartments/multivesicular bodies for virus infection.
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Affiliation(s)
- Daniel Garcia Cabanillas
- Institut National de la Recherche Scientifique, Institut Armand-Frappier, Laval, Québec H7V 1B7, Canada
| | - Jun Jiang
- Institut National de la Recherche Scientifique, Institut Armand-Frappier, Laval, Québec H7V 1B7, Canada
| | - Nooshin Movahed
- Department of Biology, McGill University, Montréal, Québec H3A 1B1, Canada
| | - Hugo Germain
- Department of Chemistry, Biochemistry, and Physics, Université du Québec à Trois-Rivières, Trois-Rivières, Québec G9A 5H7, Canada
| | - Yasuyuki Yamaji
- Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo 1138657, Japan
| | - Huanquan Zheng
- Department of Biology, McGill University, Montréal, Québec H3A 1B1, Canada
| | - Jean-François Laliberté
- Institut National de la Recherche Scientifique, Institut Armand-Frappier, Laval, Québec H7V 1B7, Canada
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27
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Takakura Y, Udagawa H, Shinjo A, Koga K. Mutation of a Nicotiana tabacum L. eukaryotic translation-initiation factor gene reduces susceptibility to a resistance-breaking strain of Potato virus Y. MOLECULAR PLANT PATHOLOGY 2018; 19:2124-2133. [PMID: 29633509 PMCID: PMC6638035 DOI: 10.1111/mpp.12686] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Revised: 03/08/2018] [Accepted: 04/03/2018] [Indexed: 05/23/2023]
Abstract
Eukaryotic translation-initiation factors eIF4E and eIF(iso)4E in plants play key roles in infection by potyviruses and other plant RNA viruses. Mutations in the genes encoding these factors reduce susceptibility to the viruses, and are the basis of several recessive virus resistance genes widely used in plant breeding. Because virus variants occasionally break such resistance, the molecular basis for this process must be elucidated. Although deletion mutants of eIF4E1-S of tobacco (Nicotiana tabacum L.) resist Potato virus Y (PVY; the type member of the genus Potyvirus), resistance-breaking strains of PVY threaten tobacco production worldwide. Here, we used RNA interference technology to knock down tobacco eIF4E2-S and eIF4E2-T genes or eIF(iso)4E-S and eIF(iso)4E-T genes. Transgenic plants with reduced transcript levels of both eIF(iso)4E-S and eIF(iso)4E-T showed reduced susceptibility to a resistance-breaking PVY strain with a K105E mutation in the viral genome-associated protein (VPg). By screening a population of chemically induced mutants of eIF(iso)4E-S and eIF(iso)4E-T, we showed that plants with a nonsense mutation in eIF(iso)4E-T, but not eIF(iso)4E-S, showed reduced susceptibility to the resistance-breaking PVY strain. In a yeast two-hybrid assay, VPg of the resistance-breaking strain, but not wild-type PVY, physically interacted with the eIF(iso)4E-T protein. Thus, eIF4E1-S is required for infection by PVY, but eIF(iso)4E-T is required for infection by the resistance-breaking strain. Our study provides the first evidence for the involvement of a host eukaryotic translation-initiation factor in the infection cycle of a resistance-breaking virus strain. The eIF(iso)4E-T mutants will be useful in tobacco breeding to introduce resistance against resistance-breaking PVY strains.
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Affiliation(s)
- Yoshimitsu Takakura
- Leaf Tobacco Research Center, Japan Tobacco, Inc.1900 Idei, OyamaTochigi 323‐0808Japan
| | - Hisashi Udagawa
- Leaf Tobacco Research Center, Japan Tobacco, Inc.1900 Idei, OyamaTochigi 323‐0808Japan
| | - Akira Shinjo
- Leaf Tobacco Research Center, Japan Tobacco, Inc.1900 Idei, OyamaTochigi 323‐0808Japan
| | - Kazuharu Koga
- Leaf Tobacco Research Center, Japan Tobacco, Inc.1900 Idei, OyamaTochigi 323‐0808Japan
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28
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Qiao W, Helpio EL, Falk BW. Two Crinivirus-Conserved Small Proteins, P5 and P9, Are Indispensable for Efficient Lettuce infectious yellows virus Infectivity in Plants. Viruses 2018; 10:E459. [PMID: 30154314 PMCID: PMC6163742 DOI: 10.3390/v10090459] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 08/24/2018] [Accepted: 08/27/2018] [Indexed: 01/06/2023] Open
Abstract
Genomic analysis of Lettuce infectious yellows virus (LIYV) has revealed two short open reading frames (ORFs) on LIYV RNA2, that are predicted to encode a 5-kDa (P5) and a 9-kDa (P9) protein. The P5 ORF is part of the conserved quintuple gene block in the family Closteroviridae, while P9 orthologs are found in all Criniviruses. In this study, the expression of LIYV P5 and P9 proteins was confirmed; P5 is further characterized as an endoplasmic reticulum (ER)-localized integral transmembrane protein and P9 is a soluble protein. The knockout LIYV mutants presented reduced symptom severity and virus accumulation in Nicotiana benthamiana or lettuce plants, indicating their importance in efficient virus infection. The P5 mutant was successfully complemented by a dislocated P5 in the LIYV genome. The structural regions of P5 were tested and all were found to be required for the appropriate functions of P5. In addition, P5, as well as its ortholog P6, encoded by Citrus tristeza virus (CTV) and another ER-localized protein encoded by LIYV RNA1, were found to cause cell death when expressed in N. benthamiana plants from a TMV vector, and induce ER stress and the unfolded protein response (UPR).
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Affiliation(s)
- Wenjie Qiao
- Department of Plant Pathology, University of California, Davis, CA 95616, USA.
| | - Erin L Helpio
- Department of Plant Pathology, University of California, Davis, CA 95616, USA.
| | - Bryce W Falk
- Department of Plant Pathology, University of California, Davis, CA 95616, USA.
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29
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Rodamilans B, Shan H, Pasin F, García JA. Plant Viral Proteases: Beyond the Role of Peptide Cutters. FRONTIERS IN PLANT SCIENCE 2018; 9:666. [PMID: 29868107 PMCID: PMC5967125 DOI: 10.3389/fpls.2018.00666] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 04/30/2018] [Indexed: 05/23/2023]
Abstract
Almost half of known plant viral species rely on proteolytic cleavages as key co- and post-translational modifications throughout their infection cycle. Most of these viruses encode their own endopeptidases, proteases with high substrate specificity that internally cleave large polyprotein precursors for the release of functional sub-units. Processing of the polyprotein, however, is not an all-or-nothing process in which endopeptidases act as simple peptide cutters. On the contrary, spatial-temporal modulation of these polyprotein cleavage events is crucial for a successful viral infection. In this way, the processing of the polyprotein coordinates viral replication, assembly and movement, and has significant impact on pathogen fitness and virulence. In this mini-review, we give an overview of plant viral proteases emphasizing their importance during viral infections and the varied functionalities that result from their proteolytic activities.
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Affiliation(s)
- Bernardo Rodamilans
- Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain
| | - Hongying Shan
- Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain
| | - Fabio Pasin
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan
| | - Juan Antonio García
- Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain
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30
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Chen I, Chen H, Huang Y, Huang H, Shenkwen L, Hsu Y, Tsai C. A thioredoxin NbTRXh2 from Nicotiana benthamiana negatively regulates the movement of Bamboo mosaic virus. MOLECULAR PLANT PATHOLOGY 2018; 19:405-417. [PMID: 28052479 PMCID: PMC6637981 DOI: 10.1111/mpp.12532] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 12/25/2016] [Accepted: 12/29/2016] [Indexed: 05/05/2023]
Abstract
An up-regulated gene derived from Bamboo mosaic virus (BaMV)-infected Nicotiana benthamiana plants was cloned and characterized in this study. BaMV is a single-stranded, positive-sense RNA virus. This gene product, designated as NbTRXh2, was matched with sequences of thioredoxin h proteins, a group of small proteins with a conserved active-site motif WCXPC conferring disulfide reductase activity. To examine how NbTRXh2 is involved in the infection cycle of BaMV, we used the virus-induced gene silencing technique to knock down NbTRXh2 expression in N. benthamiana and inoculated the plants with BaMV. We observed that, compared with control plants, BaMV coat protein accumulation increased in knockdown plants at 5 days post-inoculation (dpi). Furthermore, BaMV coat protein accumulation did not differ significantly between NbTRXh2-knockdown and control protoplasts at 24 hpi. The BaMV infection foci in NbTRXh2-knockdown plants were larger than those in control plants. In addition, BaMV coat protein accumulation decreased when NbTRXh2 was transiently expressed in plants. These results suggest that NbTRXh2 plays a role in restricting BaMV accumulation. Moreover, confocal microscopy results showed that NbTRXh2-OFP (NbTRXh2 fused with orange fluorescent protein) localized at the plasma membrane, similar to AtTRXh9, a homologue in Arabidopsis. The expression of the mutant that did not target the substrates failed to reduce BaMV accumulation. Co-immunoprecipitation experiments revealed that the viral movement protein TGBp2 could be the target of NbTRXh2. Overall, the functional role of NbTRXh2 in reducing the disulfide bonds of targeting factors, encoded either by the host or virus (TGBp2), is crucial in restricting BaMV movement.
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Affiliation(s)
- I‐Hsuan Chen
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichung402Taiwan
| | - Hui‐Ting Chen
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichung402Taiwan
| | - Ying‐Ping Huang
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichung402Taiwan
| | - Hui‐Chen Huang
- Biotechnology CenterNational Chung Hsing UniversityTaichung402Taiwan
| | - Lin‐Ling Shenkwen
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichung402Taiwan
| | - Yau‐Heiu Hsu
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichung402Taiwan
| | - Ching‐Hsiu Tsai
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichung402Taiwan
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31
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Jin X, Jiang Z, Zhang K, Wang P, Cao X, Yue N, Wang X, Zhang X, Li Y, Li D, Kang BH, Zhang Y. Three-Dimensional Analysis of Chloroplast Structures Associated with Virus Infection. PLANT PHYSIOLOGY 2018; 176:282-294. [PMID: 28821590 PMCID: PMC5761806 DOI: 10.1104/pp.17.00871] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 08/15/2017] [Indexed: 05/18/2023]
Abstract
Chloroplasts are multifunctional organelles whose morphology is affected by environmental stresses. Although the three-dimensional (3D) architecture of thylakoid membranes has been reported previously, a 3D visualization of chloroplast under stress has not been explored. In this work, we used a positive-strand RNA ((+)RNA) virus, barley stripe mosaic virus (BSMV) to observe chloroplast structural changes during infection by electron tomography. The analyses revealed remodeling of the chloroplast membranes, characterized by the clustering of outer membrane-invaginated spherules in inner membrane-derived packets. Diverse morphologies of cytoplasmic invaginations (CIs) were evident with spherules at the periphery and different sized openings connecting the CIs to the cytoplasm. Immunoelectron microscopy of these viral components verified that the aberrant membrane structures were sites for BSMV replication. The BSMV αa replication protein localized at the surface of the chloroplasts and played a prominent role in eliciting chloroplast membrane rearrangements. In sum, our results have revealed the 3D structure of the chloroplasts induced by BSMV infection. These findings contribute to our understanding of chloroplast morphological changes under stress conditions and during assembly of plant (+)RNA virus replication complexes.
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Affiliation(s)
- Xuejiao Jin
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, P.R. China
| | - Zhihao Jiang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, P.R. China
| | - Kun Zhang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, P.R. China
| | - Pengfei Wang
- School of Life Sciences, Center for Cell and Developmental Biology and State Key Laboratory of Agro-biotechnology, The Chinese University of Hong Kong, Hong Kong, P.R. China
| | - Xiuling Cao
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, P.R. China
| | - Ning Yue
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, P.R. China
| | - Xueting Wang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, P.R. China
| | - Xuan Zhang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, P.R. China
| | - Yunqin Li
- Institute of Biotechnology, Zhejiang University, Hangzhou 310058, P.R. China
| | - Dawei Li
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, P.R. China
| | - Byung-Ho Kang
- School of Life Sciences, Center for Cell and Developmental Biology and State Key Laboratory of Agro-biotechnology, The Chinese University of Hong Kong, Hong Kong, P.R. China
| | - Yongliang Zhang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, P.R. China
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32
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Jin X, Cao X, Wang X, Jiang J, Wan J, Laliberté JF, Zhang Y. Three-Dimensional Architecture and Biogenesis of Membrane Structures Associated with Plant Virus Replication. FRONTIERS IN PLANT SCIENCE 2018; 9:57. [PMID: 29441085 PMCID: PMC5797596 DOI: 10.3389/fpls.2018.00057] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 01/11/2018] [Indexed: 05/20/2023]
Abstract
Positive-sense (+) RNA viruses represent the most abundant group of viruses and are dependent on the host cell machinery to replicate. One remarkable feature that occurs after (+) RNA virus entry into cells is the remodeling of host endomembranes, leading to the formation of viral replication factories. Recently, rapid progress in three-dimensional (3D) imaging technologies, such as electron tomography (ET) and focused ion beam-scanning electron microscopy (FIB-SEM), has enabled researchers to visualize the novel membrane structures induced by viruses at high resolution. These 3D imaging technologies provide new mechanistic insights into the viral infection cycle. In this review, we summarize the latest reports on the cellular remodeling that occurs during plant virus infection; in particular, we focus on studies that provide 3D architectural information on viral replication factories. We also outline the mechanisms underlying the formation of these membranous structures and discuss possible future research directions.
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Affiliation(s)
- Xuejiao Jin
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Xiuling Cao
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Xueting Wang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Jun Jiang
- Institut National de la Recherche Scientifique—Institut Armand-Frappier, Laval, QC, Canada
| | - Juan Wan
- Institut National de la Recherche Scientifique—Institut Armand-Frappier, Laval, QC, Canada
| | - Jean-François Laliberté
- Institut National de la Recherche Scientifique—Institut Armand-Frappier, Laval, QC, Canada
- *Correspondence: Jean-François Laliberté
| | - Yongliang Zhang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, China
- Yongliang Zhang
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Park SH, Li F, Renaud J, Shen W, Li Y, Guo L, Cui H, Sumarah M, Wang A. NbEXPA1, an α-expansin, is plasmodesmata-specific and a novel host factor for potyviral infection. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 92:846-861. [PMID: 28941316 DOI: 10.1111/tpj.13723] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 09/01/2017] [Accepted: 09/07/2017] [Indexed: 05/23/2023]
Abstract
Plasmodesmata (PD), unique to the plant kingdom, are structurally complex microchannels that cross the cell wall to establish symplastic communication between neighbouring cells. Viral intercellular movement occurs through PD. To better understand the involvement of PD in viral infection, we conducted a quantitative proteomic study on the PD-enriched fraction from Nicotiana benthamiana leaves in response to infection by Turnip mosaic virus (TuMV). We report the identification of a total of 1070 PD protein candidates, of which 100 (≥2-fold increase) and 48 (≥2-fold reduction) are significantly differentially accumulated in the PD-enriched fraction, when compared with protein levels in the corresponding healthy control. Among the differentially accumulated PD protein candidates, we show that an α-expansin designated NbEXPA1, a cell wall loosening protein, is PD-specific. TuMV infection downregulates NbEXPA1 mRNA expression and protein accumulation. We further demonstrate that NbEXPA1 is recruited to the viral replication complex via the interaction with NIb, the only RNA-dependent RNA polymerase of TuMV. Silencing of NbEXPA1 inhibits plant growth and TuMV infection, whereas overexpression of NbEXPA1 promotes viral replication and intercellular movement. These data suggest that NbEXPA1 is a host factor for potyviral infection. This study not only generates a PD-proteome dataset that is useful in future studies to expound PD biology and PD-mediated virus-host interactions but also characterizes NbEXPA1 as the first PD-specific cell wall loosening protein and its essential role in potyviral infection.
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Affiliation(s)
- Sang-Ho Park
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, N5V 4T3, Canada
- Department of Biology, Western University, London, ON, N6A 5B7, Canada
| | - Fangfang Li
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, N5V 4T3, Canada
| | - Justin Renaud
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, N5V 4T3, Canada
| | - Wentao Shen
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, N5V 4T3, Canada
- Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, Hainan, 571101, China
| | - Yinzi Li
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, N5V 4T3, Canada
- Department of Biology, Western University, London, ON, N6A 5B7, Canada
| | - Lihua Guo
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, N5V 4T3, Canada
- Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Hongguang Cui
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, N5V 4T3, Canada
| | - Mark Sumarah
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, N5V 4T3, Canada
| | - Aiming Wang
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, N5V 4T3, Canada
- Department of Biology, Western University, London, ON, N6A 5B7, Canada
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Movahed N, Patarroyo C, Sun J, Vali H, Laliberté JF, Zheng H. Cylindrical Inclusion Protein of Turnip Mosaic Virus Serves as a Docking Point for the Intercellular Movement of Viral Replication Vesicles. PLANT PHYSIOLOGY 2017; 175:1732-1744. [PMID: 29089395 PMCID: PMC5717746 DOI: 10.1104/pp.17.01484] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 10/27/2017] [Indexed: 05/22/2023]
Abstract
Plant viruses move from the initially infected cell to adjacent cells through plasmodesmata (PDs). To do so, viruses encode dedicated protein(s) that facilitate this process. How viral proteins act together to support the intercellular movement of viruses is poorly defined. Here, by using an infection-free intercellular vesicle movement assay, we investigate the action of CI (cylindrical inclusion) and P3N-PIPO (amino-terminal half of P3 fused to Pretty Interesting Potyviridae open reading frame), the two PD-localized potyviral proteins encoded by Turnip mosaic virus (TuMV), in the intercellular movement of the viral replication vesicles. We provide evidence that CI and P3N-PIPO are sufficient to support the PD targeting and intercellular movement of TuMV replication vesicles induced by 6K2, a viral protein responsible for the generation of replication vesicles. 6K2 interacts with CI but not P3N-PIPO. When this interaction is impaired, the intercellular movement of TuMV replication vesicles is inhibited. Furthermore, in transmission electron microscopy, vesicular structures are observed in connection with the cylindrical inclusion bodies at structurally modified PDs in cells coexpressing 6K2, CI, and P3N-PIPO. CI is directed to PDs through its interaction with P3N-PIPO. We hypothesize that CI serves as a docking point for PD targeting and the intercellular movement of TuMV replication vesicles. This work contributes to a better understanding of the roles of different viral proteins in coordinating the intercellular movement of viral replication vesicles.
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Affiliation(s)
- Nooshin Movahed
- Department of Biology, McGill University, Montreal, Quebec H3B 1A1, Canada
| | - Camilo Patarroyo
- Department of Biology, McGill University, Montreal, Quebec H3B 1A1, Canada
| | - Jiaqi Sun
- Department of Biology, McGill University, Montreal, Quebec H3B 1A1, Canada
| | - Hojatollah Vali
- Facility for Electron Microscopy Research, McGill University, Montreal, Quebec H3A 0C7, Canada
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec H3A 0C7, Canada
| | | | - Huanquan Zheng
- Department of Biology, McGill University, Montreal, Quebec H3B 1A1, Canada
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Chen IH, Huang YP, Tseng CH, Ni JT, Tsai CH, Hsu YH, Tsai CH. Nicotiana benthamiana Elicitor-Inducible Leucine-Rich Repeat Receptor-Like Protein Assists Bamboo Mosaic Virus Cell-to-Cell Movement. FRONTIERS IN PLANT SCIENCE 2017; 8:1736. [PMID: 29056941 PMCID: PMC5635722 DOI: 10.3389/fpls.2017.01736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 09/22/2017] [Indexed: 06/07/2023]
Abstract
For successful infection, a virus requires various host factors at different stages such as translation, targeting, replication, and spreading. One of the host genes upregulated after Nicotiana benthamiana infection with Bamboo mosaic virus (BaMV), a single-stranded positive-sense RNA potexvirus, assists in viral movement. To understand how this host protein is involved in BaMV movement, we cloned its full-length cDNA by rapid amplification of cDNA ends. The gene has 3199 nt and encodes a 969-amino acid polypeptide. The sequence of the encoded polypeptide is orthologous to that of N. tabacum elicitor-inducible leucine-rich repeat (LRR) receptor-like protein (NtEILP), a plant viral resistance gene, and is designated NbEILP. To reveal how NbEILP is involved in BaMV movement, we fused green fluorescent protein (GFP) to its C-terminus. Unfortunately, the gene's expression in N. benthamiana was beyond our detection limit possibly because of its large size (∼135 kDa). However, NbEILP at such low expression could still enhance BaMV accumulation in inoculated leaves. A short version of NbEILP was constructed to remove the LRR domain, NbEILP/ΔLRR-GFP; the expression of this deletion mutant could still enhance BaMV accumulation to 1.7-fold that of the control. Hence, the LRR domain in NbEILP is not an essential element in BaMV movement. We constructed a few deletion mutants - NbEILP/ΔLRRΔTMD (without the transmembrane domain), NbEILP/ΔLRRΔCD (without the cytoplasmic domain), and NbEILP/ΔLRRΔSP (without the signal peptide) - to examine whether these domains are involved in BaMV movement. For BaMV movement, NbEILP requires the signal peptide to target the endoplasmic reticulum and the transmembrane domain to retain on the membrane.
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Cui X, Yaghmaiean H, Wu G, Wu X, Chen X, Thorn G, Wang A. The C-terminal region of the Turnip mosaic virus P3 protein is essential for viral infection via targeting P3 to the viral replication complex. Virology 2017; 510:147-155. [PMID: 28735115 DOI: 10.1016/j.virol.2017.07.016] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 07/11/2017] [Accepted: 07/13/2017] [Indexed: 10/19/2022]
Abstract
Like other positive-strand RNA viruses, plant potyviruses assemble viral replication complexes (VRCs) on modified cellular membranes. Potyviruses encode two membrane proteins, 6K2 and P3. The former is known to play pivotal roles in the formation of membrane-associated VRCs. However, P3 remains to be one of the least characterized potyviral proteins. The P3 cistron codes for P3 as well as P3N-PIPO which results from RNA polymerase slippage. In this study, we show that the P3N-PIPO of Turnip mosaic virus (TuMV) is required for viral cell-to-cell movement but not for viral replication. We demonstrate that the C-terminal region of P3 (P3C) is indispensable for P3 to form cytoplasmic punctate inclusions and target VRCs. We reveal that TuMV mutants that lack P3C are replication-defective. Taken together, these data suggest that the P3 cistron has two distinct functions: P3N-PIPO as a dedicated movement protein and P3 as an essential component of the VRC.
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Affiliation(s)
- Xiaoyan Cui
- Institute of Vegetable Crops, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu 210014, China; London Research and Development Centre, Agriculture and Agri-Food Canada, London, Ontario N5V 4T3, Canada; Department of Biology, Western University, London, Ontario N6A 5B7, Canada
| | - Hoda Yaghmaiean
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, Ontario N5V 4T3, Canada; Department of Biology, Western University, London, Ontario N6A 5B7, Canada
| | - Guanwei Wu
- Institute of Vegetable Crops, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu 210014, China; London Research and Development Centre, Agriculture and Agri-Food Canada, London, Ontario N5V 4T3, Canada; Department of Biology, Western University, London, Ontario N6A 5B7, Canada
| | - Xiaoyun Wu
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, Ontario N5V 4T3, Canada; College of Agriculture and Food Science, Zhejiang A&F University, Linan, Zhejiang 311300, China
| | - Xin Chen
- Institute of Vegetable Crops, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu 210014, China
| | - Greg Thorn
- Department of Biology, Western University, London, Ontario N6A 5B7, Canada
| | - Aiming Wang
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, Ontario N5V 4T3, Canada; Department of Biology, Western University, London, Ontario N6A 5B7, Canada.
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Qiao W, Medina V, Falk BW. Inspirations on Virus Replication and Cell-to-Cell Movement from Studies Examining the Cytopathology Induced by Lettuce infectious yellows virus in Plant Cells. FRONTIERS IN PLANT SCIENCE 2017; 8:1672. [PMID: 29021801 PMCID: PMC5623981 DOI: 10.3389/fpls.2017.01672] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 09/12/2017] [Indexed: 05/06/2023]
Abstract
Lettuce infectious yellows virus (LIYV) is the type member of the genus Crinivirus in the family Closteroviridae. Like many other positive-strand RNA viruses, LIYV infections induce a number of cytopathic changes in plant cells, of which the two most characteristic are: Beet yellows virus-type inclusion bodies composed of vesicles derived from cytoplasmic membranes; and conical plasmalemma deposits (PLDs) located at the plasmalemma over plasmodesmata pit fields. The former are not only found in various closterovirus infections, but similar structures are known as 'viral factories' or viroplasms in cells infected with diverse types of animal and plant viruses. These are generally sites of virus replication, virion assembly and in some cases are involved in cell-to-cell transport. By contrast, PLDs induced by the LIYV-encoded P26 non-virion protein are not involved in replication but are speculated to have roles in virus intercellular movement. These deposits often harbor LIYV virions arranged to be perpendicular to the plasma membrane over plasmodesmata, and our recent studies show that P26 is required for LIYV systemic plant infection. The functional mechanism of how LIYV P26 facilitates intercellular movement remains unclear, however, research on other plant viruses provides some insights on the possible ways of viral intercellular movement through targeting and modifying plasmodesmata via interactions between plant cellular components and viral-encoded factors. In summary, beginning with LIYV, we review the studies that have uncovered the biological determinants giving rise to these cytopathological effects and their importance in viral replication, virion assembly and intercellular movement during the plant infection by closteroviruses, and compare these findings with those for other positive-strand RNA viruses.
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Affiliation(s)
- Wenjie Qiao
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States
| | - Vicente Medina
- Department of Crop and Forest Sciences, University of Lleida, Lleida, Spain
| | - Bryce W. Falk
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States
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Hong JS, Ju HJ. The Plant Cellular Systems for Plant Virus Movement. THE PLANT PATHOLOGY JOURNAL 2017; 33:213-228. [PMID: 28592941 PMCID: PMC5461041 DOI: 10.5423/ppj.rw.09.2016.0198] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2016] [Revised: 11/05/2016] [Accepted: 11/13/2016] [Indexed: 05/24/2023]
Abstract
Plasmodesmata (PDs) are specialized intercellular channels that facilitate the exchange of various molecules, including sugars, ribonucleoprotein complexes, transcription factors, and mRNA. Their diameters, estimated to be 2.5 nm in the neck region, are too small to transfer viruses or viral genomes. Tobacco mosaic virus and Potexviruses are the most extensively studied viruses. In viruses, the movement protein (MP) is responsible for the PD gating that allows the intercellular movement of viral genomes. Various host factors interact with MP to regulate complicated mechanisms related to PD gating. Virus replication and assembly occur in viral replication complex (VRC) with membrane association, especially in the endoplasmic reticulum. VRC have a highly organized structure and are highly regulated by interactions among the various host factors, proteins encoded by the viral genome, and the viral genome. Virus trafficking requires host machineries, such as the cytoskeleton and the secretory systems. MP facilitates the virus replication and movement process. Despite the current level of understanding of virus movement, there are still many unknown and complex interactions between virus replication and virus movement. While numerous studies have been conducted to understand plant viruses with regards to cell-to-cell movement and replication, there are still many knowledge gaps. To study these interactions, adequate research tools must be used such as molecular, and biochemical techniques. Without such tools, virologists will not be able to gain an accurate or detailed understanding of the virus infection process.
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Affiliation(s)
- Jin-Sung Hong
- Department of Applied Biology, College of Agriculture and Life Sciences, Kangwon National University, Chuncheon 24341, Korea
| | - Ho-Jong Ju
- Department of Agricultural Biology, College of Agricultural Life Science, Chonbuk National University, Jeonju 54896, Korea
- Plant Medicinal Research Center, College of Agricultural Life Science, Chonbuk National University, Jeonju 54896, Korea
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Cheng X, Wang A. The Potyvirus Silencing Suppressor Protein VPg Mediates Degradation of SGS3 via Ubiquitination and Autophagy Pathways. J Virol 2017; 91:e01478-16. [PMID: 27795417 PMCID: PMC5165207 DOI: 10.1128/jvi.01478-16] [Citation(s) in RCA: 116] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 10/17/2016] [Indexed: 12/31/2022] Open
Abstract
RNA silencing is an innate antiviral immunity response of plants and animals. To counteract this host immune response, viruses have evolved an effective strategy to protect themselves by the expression of viral suppressors of RNA silencing (VSRs). Most potyviruses encode two VSRs, helper component-proteinase (HC-Pro) and viral genome-linked protein (VPg). The molecular biology of the former has been well characterized, whereas how VPg exerts its function in the suppression of RNA silencing is yet to be understood. In this study, we show that infection by Turnip mosaic virus (TuMV) causes reduced levels of suppressor of gene silencing 3 (SGS3), a key component of the RNA silencing pathway that functions in double-stranded RNA synthesis for virus-derived small interfering RNA (vsiRNA) production. We also demonstrate that among 11 TuMV-encoded viral proteins, VPg is the only one that interacts with SGS3. We furthermore present evidence that the expression of VPg alone, independent of viral infection, is sufficient to induce the degradation of SGS3 and its intimate partner RNA-dependent RNA polymerase 6 (RDR6). Moreover, we discover that the VPg-mediated degradation of SGS3 occurs via both the 20S ubiquitin-proteasome and autophagy pathways. Taken together, our data suggest a role for VPg-mediated degradation of SGS3 in suppression of silencing by VPg. IMPORTANCE Potyviruses represent the largest group of known plant viruses and cause significant losses of many agriculturally important crops in the world. In order to establish infection, potyviruses must overcome the host antiviral silencing response. A viral protein called VPg has been shown to play a role in this process, but how it works is unclear. In this paper, we found that the VPg protein of Turnip mosaic virus (TuMV), which is a potyvirus, interacts with a host protein named SGS3, a key protein in the RNA silencing pathway. Moreover, this interaction leads to the degradation of SGS3 and its interacting and functional partner RDR6, which is another essential component of the RNA silencing pathway. We also identified the cellular pathways that are recruited for the VPg-mediated degradation of SGS3. Therefore, this work reveals a possible mechanism by which VPg sabotages host antiviral RNA silencing to promote virus infection.
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Affiliation(s)
- Xiaofei Cheng
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada
| | - Aiming Wang
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada
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40
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Levins E, Tseng CY, Patrick RM, Mayberry LK, Cole N, Browning KS. Fusion proteins of Arabidopsis cap-binding proteins: Cautionary "tails" of woe. ACTA ACUST UNITED AC 2016; 4:e1257408. [PMID: 28090423 DOI: 10.1080/21690731.2016.1257408] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 10/21/2016] [Accepted: 11/02/2016] [Indexed: 01/25/2023]
Abstract
The use of fluorescent proteins fused to other proteins has been very useful in revealing the location and function of many proteins. However, it is very important to show that the fusion of these reporter proteins does not impact the function of the protein of interest. Plants have 2 forms of the cap-binding protein that function in initiation of translation, eIF4E and a plant specific form, eIFiso4E. In an attempt to determine the cellular localization of eIFiso4E, fusions to GFP were made, but were found to not be competent to rescue the lethal phenotype of plants lacking eIF4E and eIFiso4E. This suggested that the GFP fusions at either the N- or C-terminus of eIFiso4E were not functional. Biochemical analysis of the fusions revealed that eIFiso4E•GFP fusions were not able to bind to m7GTP Sepharose indicating that they were not functional as cap-binding proteins. Analysis of eIF4E•GFP fusions, both in yeast and in vitro, showed that the N-terminal fusion may be functional, whereas the C-terminal fusion bound m7GTP Sepharose very poorly and functioned poorly in yeast. These results highlight the importance of verification both biochemically and in vivo that reporter fusions of proteins maintain activity and are stable in order to prevent observations that may result in artifacts.
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Affiliation(s)
- Elizabeth Levins
- Department of Molecular Biosciences and Institute for Cell and Molecular Biology, University of Texas at Austin , Austin, TX, USA
| | - Ching-Ying Tseng
- Department of Molecular Biosciences and Institute for Cell and Molecular Biology, University of Texas at Austin , Austin, TX, USA
| | - Ryan M Patrick
- Department of Molecular Biosciences and Institute for Cell and Molecular Biology, University of Texas at Austin , Austin, TX, USA
| | - Laura K Mayberry
- Department of Molecular Biosciences and Institute for Cell and Molecular Biology, University of Texas at Austin , Austin, TX, USA
| | - Nicola Cole
- Department of Molecular Biosciences and Institute for Cell and Molecular Biology, University of Texas at Austin , Austin, TX, USA
| | - Karen S Browning
- Department of Molecular Biosciences and Institute for Cell and Molecular Biology, University of Texas at Austin , Austin, TX, USA
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Charon J, Theil S, Nicaise V, Michon T. Protein intrinsic disorder within the Potyvirus genus: from proteome-wide analysis to functional annotation. MOLECULAR BIOSYSTEMS 2016; 12:634-52. [PMID: 26699268 DOI: 10.1039/c5mb00677e] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Within proteins, intrinsically disordered regions (IDRs) are devoid of stable secondary and tertiary structures under physiological conditions and rather exist as dynamic ensembles of inter-converting conformers. Although ubiquitous in all domains of life, the intrinsic disorder content is highly variable in viral genomes. Over the years, functional annotations of disordered regions at the scale of the whole proteome have been conducted for several animal viruses. But to date, similar studies applied to plant viruses are still missing. Based on disorder prediction tools combined with annotation programs and evolutionary studies, we analyzed the intrinsic disorder content in Potyvirus, using a 10-species dataset representative of this genus diversity. In this paper, we revealed that: (i) the Potyvirus proteome displays high disorder content, (ii) disorder is conserved during Potyvirus evolution, suggesting a functional advantage of IDRs, (iii) IDRs evolve faster than ordered regions, and (iv) IDRs may be associated with major biological functions required for the Potyvirus cycle. Notably, the proteins P1, Coat protein (CP) and Viral genome-linked protein (VPg) display a high content of conserved disorder, enriched in specific motifs mimicking eukaryotic functional modules and suggesting strategies of host machinery hijacking. In these three proteins, IDRs are particularly conserved despite their high amino acid polymorphism, indicating a link to adaptive processes. Through this comprehensive study, we further investigate the biological relevance of intrinsic disorder in Potyvirus biology and we propose a functional annotation of potyviral proteome IDRs.
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Affiliation(s)
- Justine Charon
- UMR Biologie du Fruit et Pathologie, INRA, Villenave d'Ornon cedex, France. and UMR Biologie du Fruit et Pathologie, Université de Bordeaux, Villenave d'Ornon cedex, France
| | - Sébastien Theil
- UMR Biologie du Fruit et Pathologie, INRA, Villenave d'Ornon cedex, France. and UMR Biologie du Fruit et Pathologie, Université de Bordeaux, Villenave d'Ornon cedex, France
| | - Valérie Nicaise
- UMR Biologie du Fruit et Pathologie, INRA, Villenave d'Ornon cedex, France. and UMR Biologie du Fruit et Pathologie, Université de Bordeaux, Villenave d'Ornon cedex, France
| | - Thierry Michon
- UMR Biologie du Fruit et Pathologie, INRA, Villenave d'Ornon cedex, France. and UMR Biologie du Fruit et Pathologie, Université de Bordeaux, Villenave d'Ornon cedex, France
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Li H, Kondo H, Kühne T, Shirako Y. Barley Yellow Mosaic Virus VPg Is the Determinant Protein for Breaking eIF4E-Mediated Recessive Resistance in Barley Plants. FRONTIERS IN PLANT SCIENCE 2016; 7:1449. [PMID: 27746794 PMCID: PMC5043020 DOI: 10.3389/fpls.2016.01449] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 09/12/2016] [Indexed: 05/25/2023]
Abstract
In this study, we investigated the barley yellow mosaic virus (BaYMV, genus Bymovirus) factor(s) responsible for breaking eIF4E-mediated recessive resistance genes (rym4/5/6) in barley. Genome mapping analysis using chimeric infectious cDNA clones between rym5-breaking (JT10) and rym5-non-breaking (JK05) isolates indicated that genome-linked viral protein (VPg) is the determinant protein for breaking the rym5 resistance. Likewise, VPg is also responsible for overcoming the resistances of rym4 and rym6 alleles. Mutational analysis identified that amino acids Ser-118, Thr-120, and His-142 in JT10 VPg are the most critical residues for overcoming rym5 resistance in protoplasts. Moreover, the rym5-non-breaking JK05 could accumulate in the rym5 protoplasts when eIF4E derived from a susceptible barley cultivar was expressed from the viral genome. Thus, the compatibility between VPg and host eIF4E determines the ability of BaYMV to infect barley plants.
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Affiliation(s)
- Huangai Li
- Graduate School of Agricultural and Life Sciences, The University of TokyoTokyo, Japan
- Asian Natural Environmental Science Center, The University of TokyoTokyo, Japan
| | - Hideki Kondo
- Institute of Plant Science and Resources, Okayama UniversityKurashiki, Japan
| | - Thomas Kühne
- Institute for Epidemiology and Pathogen Diagnostics, Julius Kühn-InstitutQuedlinburg, Germany
| | - Yukio Shirako
- Asian Natural Environmental Science Center, The University of TokyoTokyo, Japan
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Lõhmus A, Varjosalo M, Mäkinen K. Protein composition of 6K2-induced membrane structures formed during Potato virus A infection. MOLECULAR PLANT PATHOLOGY 2016; 17:943-58. [PMID: 26574906 PMCID: PMC6638329 DOI: 10.1111/mpp.12341] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 10/19/2015] [Accepted: 10/23/2015] [Indexed: 05/13/2023]
Abstract
The definition of the precise molecular composition of membranous replication compartments is a key to understanding the mechanisms of virus multiplication. Here, we set out to investigate the protein composition of the potyviral replication complexes. We purified the potyviral 6K2 protein-induced membranous structures from Potato virus A (PVA)-infected Nicotiana benthamiana plants. For this purpose, the 6K2 protein, which is the main inducer of potyviral membrane rearrangements, was expressed in fusion with an N-terminal Twin-Strep-tag and Cerulean fluorescent protein (SC6K) from the infectious PVA cDNA. A non-tagged Cerulean-6K2 (C6K) virus and the SC6K protein alone in the absence of infection were used as controls. A purification scheme exploiting discontinuous sucrose gradient centrifugation followed by Strep-tag-based affinity chromatography was developed. Both (+)- and (-)-strand PVA RNA and viral protein VPg were co-purified specifically with the affinity tagged PVA-SC6K. The purified samples, which contained individual vesicles and membrane clusters, were subjected to mass spectrometry analysis. Data analysis revealed that many of the detected viral and host proteins were either significantly enriched or fully specifically present in PVA-SC6K samples when compared with the controls. Eight of eleven potyviral proteins were identified with high confidence from the purified membrane structures formed during PVA infection. Ribosomal proteins were identified from the 6K2-induced membranes only in the presence of a replicating virus, reinforcing the tight coupling between replication and translation. A substantial number of proteins associating with chloroplasts and several host proteins previously linked with potyvirus replication complexes were co-purified with PVA-derived SC6K, supporting the conclusion that the host proteins identified in this study may have relevance in PVA replication.
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Affiliation(s)
- Andres Lõhmus
- Department of Food and Environmental Sciences, Viikki Plant Science Centre, 00014 University of Helsinki, Finland
| | - Markku Varjosalo
- Institute of Biotechnology, 00014 University of Helsinki, Finland
| | - Kristiina Mäkinen
- Department of Food and Environmental Sciences, Viikki Plant Science Centre, 00014 University of Helsinki, Finland
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Cui H, Wang A. Plum Pox Virus 6K1 Protein Is Required for Viral Replication and Targets the Viral Replication Complex at the Early Stage of Infection. J Virol 2016; 90:5119-5131. [PMID: 26962227 PMCID: PMC4859702 DOI: 10.1128/jvi.00024-16] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 03/07/2016] [Indexed: 01/08/2023] Open
Abstract
UNLABELLED The potyviral RNA genome encodes two polyproteins that are proteolytically processed by three viral protease domains into 11 mature proteins. Extensive molecular studies have identified functions for the majority of the viral proteins. For example, 6K2, one of the two smallest potyviral proteins, is an integral membrane protein and induces the endoplasmic reticulum (ER)-originated replication vesicles that target the chloroplast for robust viral replication. However, the functional role of 6K1, the other smallest protein, remains uncharacterized. In this study, we developed a series of recombinant full-length viral cDNA clones derived from a Canadian Plum pox virus (PPV) isolate. We found that deletion of any of the short motifs of 6K1 (each of which ranged from 5 to 13 amino acids), most of the 6K1 sequence (but with the conserved sequence of the cleavage sites being retained), or all of the 6K1 sequence in the PPV infectious clone abolished viral replication. The trans expression of 6K1 or the cis expression of a dislocated 6K1 failed to rescue the loss-of-replication phenotype, suggesting the temporal and spatial requirement of 6K1 for viral replication. Disruption of the N- or C-terminal cleavage site of 6K1, which prevented the release of 6K1 from the polyprotein, either partially or completely inhibited viral replication, suggesting the functional importance of the mature 6K1. We further found that green fluorescent protein-tagged 6K1 formed punctate inclusions at the viral early infection stage and colocalized with chloroplast-bound viral replicase elements 6K2 and NIb. Taken together, our results suggest that 6K1 is required for viral replication and is an important viral element of the viral replication complex at the early infection stage. IMPORTANCE Potyviruses account for more than 30% of known plant viruses and consist of many agriculturally important viruses. The genomes of potyviruses encode two polyproteins that are proteolytically processed into 11 mature proteins, with the majority of them having been at least partially functionally characterized. However, the functional role of a small protein named 6K1 remains obscure. In this study, we showed that deletion of 6K1 or a short motif/region of 6K1 in the full-length cDNA clones of plum pox virus abolishes viral replication and that mutation of the N- or C-terminal cleavage sites of 6K1 to prevent its release from the polyprotein greatly attenuates or completely inhibits viral replication, suggesting its important role in potyviral infection. We report that 6K1 forms punctate structures and targets the replication vesicles in PPV-infected plant leaf cells at the early infection stage. Our data reveal that 6K1 is an important viral protein of the potyviral replication complex.
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Affiliation(s)
- Hongguang Cui
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada
| | - Aiming Wang
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada
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Wan J, Basu K, Mui J, Vali H, Zheng H, Laliberté JF. Ultrastructural Characterization of Turnip Mosaic Virus-Induced Cellular Rearrangements Reveals Membrane-Bound Viral Particles Accumulating in Vacuoles. J Virol 2015; 89:12441-56. [PMID: 26423955 PMCID: PMC4665257 DOI: 10.1128/jvi.02138-15] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 09/26/2015] [Indexed: 01/02/2023] Open
Abstract
UNLABELLED Positive-strand RNA [(+) RNA] viruses remodel cellular membranes to facilitate virus replication and assembly. In the case of turnip mosaic virus (TuMV), the viral membrane protein 6K2 plays an essential role in endomembrane alterations. Although 6K2-induced membrane dynamics have been widely studied by confocal microscopy, the ultrastructure of this remodeling has not been extensively examined. In this study, we investigated the formation of TuMV-induced membrane changes by chemical fixation and high-pressure freezing/freeze substitution (HPF/FS) for transmission electron microscopy at different times of infection. We observed the formation of convoluted membranes connected to rough endoplasmic reticulum (rER) early in the infection process, followed by the production of single-membrane vesicle-like (SMVL) structures at the midstage of infection. Both SMVL and double-membrane vesicle-like structures with electron-dense cores, as well as electron-dense bodies, were found late in the infection process. Immunogold labeling results showed that the vesicle-like structures were 6K2 tagged and suggested that only the SMVL structures were viral RNA replication sites. Electron tomography (ET) was used to regenerate a three-dimensional model of these vesicle-like structures, which showed that they were, in fact, tubules. Late in infection, we observed filamentous particle bundles associated with electron-dense bodies, which suggests that these are sites for viral particle assembly. In addition, TuMV particles were observed to accumulate in the central vacuole as membrane-associated linear arrays. Our work thus unravels the sequential appearance of distinct TuMV-induced membrane structures for viral RNA replication, viral particle assembly, and accumulation. IMPORTANCE Positive-strand RNA viruses remodel cellular membranes for different stages of the infection process, such as protein translation and processing, viral RNA synthesis, particle assembly, and virus transmission. The ultrastructure of turnip mosaic virus (TuMV)-induced membrane remodeling was investigated over several days of infection. The first change that was observed involved endoplasmic reticulum-connected convoluted membrane accumulation. This was followed by the formation of single-membrane tubules, which were shown to be viral RNA replication sites. Later in the infection process, double-membrane tubular structures were observed and were associated with viral particle bundles. In addition, TuMV particles were observed to accumulate in the central vacuole as membrane-associated linear arrays. This work thus unravels the sequential appearance of distinct TuMV-induced membrane structures for viral RNA replication, viral particle assembly, and accumulation.
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Affiliation(s)
- Juan Wan
- INRS-Institut Armand-Frappier, Laval, Québec, Canada
| | - Kaustuv Basu
- Facility for Electron Microscopy Research, McGill University, Montréal, Québec, Canada
| | - Jeannie Mui
- Facility for Electron Microscopy Research, McGill University, Montréal, Québec, Canada
| | - Hojatollah Vali
- Facility for Electron Microscopy Research, McGill University, Montréal, Québec, Canada Department of Anatomy & Cell Biology, McGill University, Montréal, Québec, Canada
| | - Huanquan Zheng
- Department of Biology, McGill University, Montréal, Québec, Canada
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46
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Wan J, Basu K, Mui J, Vali H, Zheng H, Laliberté JF. Ultrastructural Characterization of Turnip Mosaic Virus-Induced Cellular Rearrangements Reveals Membrane-Bound Viral Particles Accumulating in Vacuoles. J Virol 2015. [PMID: 26423955 DOI: 10.1128/jvi.02138.15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2023] Open
Abstract
UNLABELLED Positive-strand RNA [(+) RNA] viruses remodel cellular membranes to facilitate virus replication and assembly. In the case of turnip mosaic virus (TuMV), the viral membrane protein 6K2 plays an essential role in endomembrane alterations. Although 6K2-induced membrane dynamics have been widely studied by confocal microscopy, the ultrastructure of this remodeling has not been extensively examined. In this study, we investigated the formation of TuMV-induced membrane changes by chemical fixation and high-pressure freezing/freeze substitution (HPF/FS) for transmission electron microscopy at different times of infection. We observed the formation of convoluted membranes connected to rough endoplasmic reticulum (rER) early in the infection process, followed by the production of single-membrane vesicle-like (SMVL) structures at the midstage of infection. Both SMVL and double-membrane vesicle-like structures with electron-dense cores, as well as electron-dense bodies, were found late in the infection process. Immunogold labeling results showed that the vesicle-like structures were 6K2 tagged and suggested that only the SMVL structures were viral RNA replication sites. Electron tomography (ET) was used to regenerate a three-dimensional model of these vesicle-like structures, which showed that they were, in fact, tubules. Late in infection, we observed filamentous particle bundles associated with electron-dense bodies, which suggests that these are sites for viral particle assembly. In addition, TuMV particles were observed to accumulate in the central vacuole as membrane-associated linear arrays. Our work thus unravels the sequential appearance of distinct TuMV-induced membrane structures for viral RNA replication, viral particle assembly, and accumulation. IMPORTANCE Positive-strand RNA viruses remodel cellular membranes for different stages of the infection process, such as protein translation and processing, viral RNA synthesis, particle assembly, and virus transmission. The ultrastructure of turnip mosaic virus (TuMV)-induced membrane remodeling was investigated over several days of infection. The first change that was observed involved endoplasmic reticulum-connected convoluted membrane accumulation. This was followed by the formation of single-membrane tubules, which were shown to be viral RNA replication sites. Later in the infection process, double-membrane tubular structures were observed and were associated with viral particle bundles. In addition, TuMV particles were observed to accumulate in the central vacuole as membrane-associated linear arrays. This work thus unravels the sequential appearance of distinct TuMV-induced membrane structures for viral RNA replication, viral particle assembly, and accumulation.
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Affiliation(s)
- Juan Wan
- INRS-Institut Armand-Frappier, Laval, Québec, Canada
| | - Kaustuv Basu
- Facility for Electron Microscopy Research, McGill University, Montréal, Québec, Canada
| | - Jeannie Mui
- Facility for Electron Microscopy Research, McGill University, Montréal, Québec, Canada
| | - Hojatollah Vali
- Facility for Electron Microscopy Research, McGill University, Montréal, Québec, Canada Department of Anatomy & Cell Biology, McGill University, Montréal, Québec, Canada
| | - Huanquan Zheng
- Department of Biology, McGill University, Montréal, Québec, Canada
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Zhu J, Wang B, Miao Q, Tan Y, Li C, Chen Z, Guo H, Liu G. Viral Genome-Linked Protein (VPg) Is Essential for Translation Initiation of Rabbit Hemorrhagic Disease Virus (RHDV). PLoS One 2015; 10:e0143467. [PMID: 26599265 PMCID: PMC4657913 DOI: 10.1371/journal.pone.0143467] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 11/05/2015] [Indexed: 11/27/2022] Open
Abstract
Rabbit hemorrhagic disease virus (RHDV), the causative agent of rabbit hemorrhagic disease, is an important member of the caliciviridae family. Currently, no suitable tissue culture system is available for proliferating RHDV, limiting the study of the pathogenesis of RHDV. In addition, the mechanisms underlying RHDV translation and replication are largely unknown compared with other caliciviridae viruses. The RHDV replicon recently constructed in our laboratory provides an appropriate model to study the pathogenesis of RHDV without in vitro RHDV propagation and culture. Using this RHDV replicon, we demonstrated that the viral genome-linked protein (VPg) is essential for RHDV translation in RK-13 cells for the first time. In addition, we showed that VPg interacts with eukaryotic initiation factor 4E (eIF4E) in vivo and in vitro and that eIF4E silencing inhibits RHDV translation, suggesting the interaction between VPg and eIF4E is involved in RHDV translation. Our results support the hypothesis that VPg serves as a novel cap substitute during the initiation of RHDV translation.
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Affiliation(s)
- Jie Zhu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, 200241, China
| | - Binbin Wang
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, 200241, China
| | - Qiuhong Miao
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, 200241, China
| | - Yonggui Tan
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, 200241, China
| | - Chuanfeng Li
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, 200241, China
| | - Zongyan Chen
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, 200241, China
| | - Huimin Guo
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, 200241, China
| | - Guangqing Liu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, 200241, China
- * E-mail:
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Zhang XE, Cui Z, Wang D. Sensing of biomolecular interactions using fluorescence complementing systems in living cells. Biosens Bioelectron 2015; 76:243-50. [PMID: 26316254 DOI: 10.1016/j.bios.2015.07.069] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2015] [Revised: 07/28/2015] [Accepted: 07/29/2015] [Indexed: 01/09/2023]
Abstract
Sensing biomolecule interactions in living cells allows for a deeper understanding of the mechanisms governing biological processes, and has increasing significance for improvements in clinical diagnosis. It is now possible by using molecular biosensors. One method involving molecular biosensors is called molecular fluorescence complementation, usually referred to as BiFC (bimolecular fragment/fluorescence complementary/complementation) or TriFC (trimolecular fragment complementary/complementation). This complementation method is based on the principle that two non-fluorescent fragments of a fluorescent protein are brought into sufficient lyclose proximity, upon which they are reconstructed so that fluorescence is re-established. This process relies on the interaction between the two fusion partners, which normally are proteins. This method is simple, noninvasive, sensitive, and does not require specialized tools, hence being available to most standard laboratories. Here, we selectively describe three relevant examples, although many other molecular interactions have been shown to work with this method. Recent developments of this method include multicolor BiFC, which allows for simultaneous detection of multi-biomolecule interactions, RNA-protein interactions, far red and near infrared sensing systems for deep tissue imaging. Challenges in the utilization of this method are discussed. Given the current rate of technological advancements, we believe that fluorescence fragment complementing systems have the potential to be utilized across a wide range of areas, including in routine research and clinical diagnosis.
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Affiliation(s)
- Xian-En Zhang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
| | - Zongqiang Cui
- State Key Laboratory of Virology and Center for Analytical Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, China
| | - Dianbing Wang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
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Jiang J, Patarroyo C, Garcia Cabanillas D, Zheng H, Laliberté JF. The Vesicle-Forming 6K2 Protein of Turnip Mosaic Virus Interacts with the COPII Coatomer Sec24a for Viral Systemic Infection. J Virol 2015. [PMID: 25878114 DOI: 10.1128/jvi.00503-515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023] Open
Abstract
UNLABELLED Positive-sense RNA viruses remodel host cell endomembranes to generate quasi-organelles known as "viral factories" to coordinate diverse viral processes, such as genome translation and replication. It is also becoming clear that enclosing viral RNA (vRNA) complexes within membranous structures is important for virus cell-to-cell spread throughout the host. In plant cells infected by turnip mosaic virus (TuMV), a member of the family Potyviridae, peripheral motile endoplasmic reticulum (ER)-derived viral vesicles are produced that carry the vRNA to plasmodesmata for delivery into adjacent noninfected cells. The viral protein 6K2 is responsible for the formation of these vesicles, but how 6K2 is involved in their biogenesis is unknown. We show here that 6K2 is associated with cellular membranes. Deletion mapping and site-directed mutagenesis experiments defined a soluble N-terminal 12-amino-acid stretch, in particular a potyviral highly conserved tryptophan residue and two lysine residues that were important for vesicle formation. When the tryptophan residue was changed into an alanine in the viral polyprotein, virus replication still took place, albeit at a reduced level, but cell-to-cell movement of the virus was abolished. Yeast (Saccharomyces cerevisiae) two-hybrid and coimmunoprecipitation experiments showed that 6K2 interacted with Sec24a, a COPII coatomer component. Appropriately, TuMV systemic movement was delayed in an Arabidopsis thaliana mutant line defective in Sec24a. Intercellular movement of TuMV replication vesicles thus requires ER export of 6K2, which is mediated by the interaction of the N-terminal domain of the viral protein with Sec24a. IMPORTANCE Many plant viruses remodel the endoplasmic reticulum (ER) to generate vesicles that are associated with the virus replication complex. The viral protein 6K2 of turnip mosaic virus (TuMV) is known to induce ER-derived vesicles that contain vRNA as well as viral and host proteins required for vRNA synthesis. These vesicles not only sustain vRNA synthesis, they are also involved in the intercellular trafficking of vRNA. In this investigation, we found that the N-terminal soluble domain of 6K2 is required for ER export of the protein and for the formation of vesicles. ER export is not absolutely required for vRNA replication but is necessary for virus cell-to-cell movement. Furthermore, we found that 6K2 physically interacts with the COPII coatomer Sec24a and that an Arabidopsis thaliana mutant line with a defective Sec24a shows a delay in the systemic infection by TuMV.
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Affiliation(s)
- Jun Jiang
- INRS-Institut Armand-Frappier, Laval, Québec, Canada
| | - Camilo Patarroyo
- Department of Biology, McGill University, Montréal, Québec, Canada
| | | | - Huanquan Zheng
- Department of Biology, McGill University, Montréal, Québec, Canada
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50
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Plant Translation Factors and Virus Resistance. Viruses 2015; 7:3392-419. [PMID: 26114476 PMCID: PMC4517107 DOI: 10.3390/v7072778] [Citation(s) in RCA: 144] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 06/18/2015] [Accepted: 06/19/2015] [Indexed: 02/06/2023] Open
Abstract
Plant viruses recruit cellular translation factors not only to translate their viral RNAs but also to regulate their replication and potentiate their local and systemic movement. Because of the virus dependence on cellular translation factors, it is perhaps not surprising that many natural plant recessive resistance genes have been mapped to mutations of translation initiation factors eIF4E and eIF4G or their isoforms, eIFiso4E and eIFiso4G. The partial functional redundancy of these isoforms allows specific mutation or knock-down of one isoform to provide virus resistance without hindering the general health of the plant. New possible targets for antiviral strategies have also been identified following the characterization of other plant translation factors (eIF4A-like helicases, eIF3, eEF1A and eEF1B) that specifically interact with viral RNAs and proteins and regulate various aspects of the infection cycle. Emerging evidence that translation repression operates as an alternative antiviral RNA silencing mechanism is also discussed. Understanding the mechanisms that control the development of natural viral resistance and the emergence of virulent isolates in response to these plant defense responses will provide the basis for the selection of new sources of resistance and for the intelligent design of engineered resistance that is broad-spectrum and durable.
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