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Wu WC, Chen IH, Hou PY, Wang LH, Tsai CH, Cheng CP. The phosphorylation of the movement protein TGBp1 regulates the accumulation of the Bamboo mosaic virus. J Gen Virol 2024; 105. [PMID: 38189334 DOI: 10.1099/jgv.0.001945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2024] Open
Abstract
Phosphorylation and dephosphorylation of viral movement proteins plays a crucial role in regulating virus movement. Our study focused on investigating the movement protein TGBp1 of Bamboo mosaic virus (BaMV), which is a single-stranded positive-sense RNA virus. Specifically, we examined four potential phosphorylation sites (S15, S18, T58, and S247) within the TGBp1 protein. To study the impact of phosphorylation, we introduced amino acid substitutions at the selected sites. Alanine substitutions were used to prevent phosphorylation, while aspartate substitutions were employed to mimic phosphorylation. Our findings suggest that mimicking phosphorylation at S15, S18 and T58 of TGBp1 might be linked to silencing suppressor activities. The phosphorylated form at these sites exhibits a loss of silencing suppressor activity, leading to reduced viral accumulation in the inoculated leaves. Furthermore, mimicking phosphorylation at residues S15 and S18 could diminish viral accumulation at the single-cell level, while doing so at residue T58 could influence virus movement. However, mimicking phosphorylation at residue S247 does not appear to be relevant to both functions of TGBp1. Overall, our study provides insights into the functional significance of specific phosphorylation sites in BaMV TGBp1, illuminating the regulatory mechanisms involved in virus movement and silencing suppression.
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Affiliation(s)
- Wan-Chen Wu
- Department of Biomedical Sciences and Engineering, Tzu Chi University, Hualien, 970, Taiwan, ROC
| | - I-Hsuan Chen
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 402, Taiwan, ROC
- Advanced Plant and Food Crop Biotechnology Center, National Chung Hsing University, Taichung, 402, Taiwan, ROC
| | - Pei-Yu Hou
- Department of Biomedical Sciences and Engineering, Tzu Chi University, Hualien, 970, Taiwan, ROC
| | - Lan-Hui Wang
- Department of Biomedical Sciences and Engineering, Tzu Chi University, Hualien, 970, Taiwan, ROC
| | - Ching-Hsiu Tsai
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 402, Taiwan, ROC
- Advanced Plant and Food Crop Biotechnology Center, National Chung Hsing University, Taichung, 402, Taiwan, ROC
| | - Chi-Ping Cheng
- Department of Biomedical Sciences and Engineering, Tzu Chi University, Hualien, 970, Taiwan, ROC
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Huang Y, Chen I, Kao Y, Hsu Y, Tsai C. The gibberellic acid derived from the plastidial MEP pathway is involved in the accumulation of Bamboo mosaic virus. THE NEW PHYTOLOGIST 2022; 235:1543-1557. [PMID: 35524450 PMCID: PMC9543464 DOI: 10.1111/nph.18210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 04/12/2022] [Indexed: 06/14/2023]
Abstract
A gene upregulated in Nicotiana benthamiana after Bamboo mosaic virus (BaMV) infection was revealed as 1-deoxy-d-xylulose-5-phosphate reductoisomerase (NbDXR). DXR is the key enzyme in the 2-C-methyl-d-erythritol-4-phosphate (MEP) pathway that catalyzes the conversion of 1-deoxy-d-xylulose 5-phosphate to 2-C-methyl-d-erythritol-4-phosphate. Knockdown and overexpression of NbDXR followed by BaMV inoculation revealed that NbDXR is involved in BaMV accumulation. Treating leaves with fosmidomycin, an inhibitor of DXR function, reduced BaMV accumulation. Subcellular localization confirmed that DXR is a chloroplast-localized protein by confocal microscopy. Furthermore, knockdown of 1-hydroxy-2-methyl-2-(E)-butenyl-4-diphosphate reductase, one of the enzymes in the MEP pathway, also reduced BaMV accumulation. The accumulation of BaMV increased significantly in protoplasts treated with isopentenyl pyrophosphate. Thus, the metabolites of the MEP pathway could be involved in BaMV infection. To identify the critical components involved in BaMV accumulation, we knocked down the crucial enzyme of isoprenoid synthesis, NbGGPPS11 or NbGGPPS2. Only NbGGPPS2 was involved in BaMV infection. The geranylgeranyl pyrophosphate (GGPP) synthesized by NbGGPPS2 is known for gibberellin synthesis. We confirmed this result by supplying gibberellic acid exogenously on leaves, which increased BaMV accumulation. The de novo synthesis of gibberellic acid could assist BaMV accumulation.
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Affiliation(s)
- Ying‐Ping Huang
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichung402Taiwan
| | - I‐Hsuan Chen
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichung402Taiwan
| | - Yu‐Shun Kao
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichung402Taiwan
| | - Yau‐Heiu Hsu
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichung402Taiwan
- Advaced Plant Biotechnology CenterNational Chung Hsing UniversityTaichung402Taiwan
| | - Ching‐Hsiu Tsai
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichung402Taiwan
- Advaced Plant Biotechnology CenterNational Chung Hsing UniversityTaichung402Taiwan
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Huang FC, Chi SF, Chien PR, Liu YT, Chang HN, Lin CS, Hwang HH. Arabidopsis RAB8A, RAB8B and RAB8D Proteins Interact with Several RTNLB Proteins and are Involved in the Agrobacterium tumefaciens Infection Process. PLANT & CELL PHYSIOLOGY 2021; 62:1572-1588. [PMID: 34255832 DOI: 10.1093/pcp/pcab112] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 07/01/2021] [Accepted: 07/13/2021] [Indexed: 06/13/2023]
Abstract
Arabidopsis thaliana small GTP-binding proteins, AtRAB8s, associate with the endomembrane system and modulate tubulovesicular trafficking between compartments of the biosynthetic and endocytic pathways. There are five members in Arabidopsis, namely AtRAB8A-8E. Yeast two-hybrid assays, bimolecular fluorescence complementation assays and glutathione-S-transferase pull-down assays showed that RAB8A, 8B and 8D interacted with several membrane-associated reticulon-like (AtRTNLB) proteins in yeast, plant cells and in vitro. Furthermore, RAB8A, 8B and 8D proteins showed interactions with the Agrobacterium tumefaciens virulence protein, VirB2, a component of a type IV secretion system (T4SS). A. tumefaciens uses a T4SS to transfer T-DNA and Virulence proteins to plants, which causes crown gall disease in plants. The Arabidopsis rab8A, rab8B and rab8D single mutants showed decreased levels of Agrobacterium-mediated root and seedling transformation, while the RAB8A, 8B and 8D overexpression transgenic Arabidopsis plants were hypersusceptible to A. tumefaciens and Pseudomonas syringae infections. RAB8A-8E transcripts accumulated differently in roots, rosette leaves, cauline leaves, inflorescence and flowers of wild-type plants. In summary, RAB8A, 8B and 8D interacted with several RTNLB proteins and participated in A. tumefaciens and P. syringae infection processes.
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Affiliation(s)
- Fan-Chen Huang
- Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan
| | - Shin-Fei Chi
- Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan
| | - Pei-Ru Chien
- Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan
| | - Yin-Tzu Liu
- Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan
| | - Hsin-Nung Chang
- Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan
| | - Choun-Sea Lin
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Hau-Hsuan Hwang
- Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan
- Innovation and Development Center of Sustainable Agriculture, National Chung Hsing University, Taichung 402, Taiwan
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Feng Z, Inaba JI, Nagy PD. Tombusviruses Target a Major Crossroad in the Endocytic and Recycling Pathways via Co-opting Rab7 Small GTPase. J Virol 2021; 95:e0107621. [PMID: 34406861 PMCID: PMC8513485 DOI: 10.1128/jvi.01076-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 08/13/2021] [Indexed: 12/28/2022] Open
Abstract
Positive-strand RNA viruses induce the biogenesis of unique membranous organelles called viral replication organelles (VROs), which perform virus replication in infected cells. Tombusviruses have been shown to rewire cellular trafficking and metabolic pathways, remodel host membranes, and recruit multiple host factors to support viral replication. In this work, we demonstrate that tomato bushy stunt virus (TBSV) and the closely related carnation Italian ringspot virus (CIRV) usurp Rab7 small GTPase to facilitate building VROs in the surrogate host yeast and in plants. Depletion of Rab7 small GTPase, which is needed for late endosome and retromer biogenesis, strongly inhibits TBSV and CIRV replication in yeast and in planta. The viral p33 replication protein interacts with Rab7 small GTPase, which results in the relocalization of Rab7 into the large VROs. Similar to the depletion of Rab7, the deletion of either MON1 or CCZ1 heterodimeric GEFs (guanine nucleotide exchange factors) of Rab7 inhibited TBSV RNA replication in yeast. This suggests that the activated Rab7 has proviral functions. We show that the proviral function of Rab7 is to facilitate the recruitment of the retromer complex and the endosomal sorting nexin-BAR proteins into VROs. We demonstrate that TBSV p33-driven retargeting of Rab7 into VROs results in the delivery of several retromer cargos with proviral functions. These proteins include lipid enzymes, such as Vps34 PI3K (phosphatidylinositol 3-kinase), PI4Kα-like Stt4 phosphatidylinositol 4-kinase, and Psd2 phosphatidylserine decarboxylase. In summary, based on these and previous findings, we propose that subversion of Rab7 into VROs allows tombusviruses to reroute endocytic and recycling trafficking to support virus replication. IMPORTANCE The replication of positive-strand RNA viruses depends on the biogenesis of viral replication organelles (VROs). However, the formation of membranous VROs is not well understood yet. Using tombusviruses and the model host yeast, we discovered that the endosomal Rab7 small GTPase is critical for the formation of VROs. Interaction between Rab7 and the TBSV p33 replication protein leads to the recruitment of Rab7 into VROs. TBSV-driven usurping of Rab7 has proviral functions through facilitating the delivery of the co-opted retromer complex, sorting nexin-BAR proteins, and lipid enzymes into VROs to create an optimal milieu for virus replication. These results open up the possibility that controlling cellular Rab7 activities in infected cells could be a target for new antiviral strategies.
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Affiliation(s)
- Zhike Feng
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, USA
| | - Jun-ichi Inaba
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, USA
| | - Peter D. Nagy
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, USA
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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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Huang YP, Hou PY, Chen IH, Hsu YH, Tsai CH, Cheng CP. Dissecting the role of a plant-specific Rab5 small GTPase NbRabF1 in Bamboo mosaic virus infection. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:6932-6944. [PMID: 32926136 DOI: 10.1093/jxb/eraa422] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
NbRabF1, a small GTPase from Nicotiana benthamiana and a homolog of Arabidopsis thaliana Ara6, plays a key role in regulating Bamboo mosaic virus (BaMV) movement by vesicle transport between endosomal membranes. Reducing the expression of NbRabF1 in N. benthamiana by virus-induced gene silencing decreased the accumulation of BaMV, and with smaller infection foci on inoculated leaves, but had no effect in protoplasts. Furthermore, transient expression of NbRabF1 increased the accumulation of BaMV in inoculated leaves. Thus, NbRabF1 may be involved in the cell-to-cell movement of BaMV. The potential acyl modification sites at the second and third amino acid positions of NbRabF1 were crucial for membrane targeting and BaMV accumulation. The localization of mutant forms of NbRabF1 with the GDP-bound (donor site) and GTP-bound (acceptor site) suggested that NbRabF1 might regulate vesicle trafficking between the Golgi apparatus and plasma membrane. Furthermore, GTPase activity could also be involved in BaMV cell-to-cell movement. Overall, in this study, we identified a small GTPase, NbRabF1, from N. benthamiana that interacts with its activation protein NbRabGAP1 and regulates vesicle transport from the Golgi apparatus to the plasma membrane. We suggest that the BaMV movement complex might move from cell to cell through this vesicle trafficking route.
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Affiliation(s)
- Ying-Ping Huang
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Pei-Yu Hou
- Department of Life Sciences, Tzu Chi University, Hualien, Taiwan
| | - I-Hsuan Chen
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Yau-Huei Hsu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
- Advanced Plant Biotechnology Center, National Chung Hsing University, Taichung, Taiwan
| | - Ching-Hsiu Tsai
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
- Advanced Plant Biotechnology Center, National Chung Hsing University, Taichung, Taiwan
- Research Center for Sustainable Energy and Nanotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Chi-Ping Cheng
- Department of Life Sciences, Tzu Chi University, Hualien, Taiwan
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Chiu LY, Chen IH, Hsu YH, Tsai CH. The Lipid Transfer Protein 1 from Nicotiana benthamiana Assists Bamboo mosaic virus Accumulation. Viruses 2020; 12:E1361. [PMID: 33261222 PMCID: PMC7760991 DOI: 10.3390/v12121361] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 11/23/2020] [Accepted: 11/25/2020] [Indexed: 12/16/2022] Open
Abstract
Host factors play a pivotal role in regulating virus infection. Uncovering the mechanism of how host factors are involved in virus infection could pave the way to defeat viral disease. In this study, we characterized a lipid transfer protein, designated NbLTP1 in Nicotiana benthamiana, which was downregulated after Bamboo mosaic virus (BaMV) inoculation. BaMV accumulation significantly decreased in NbLTP1-knockdown leaves and protoplasts compared with the controls. The subcellular localization of the NbLTP1-orange fluorescent protein (OFP) was mainly the extracellular matrix. However, when we removed the signal peptide (NbLTP1/ΔSP-OFP), most of the expressed protein targeted chloroplasts. Both NbLTP1-OFP and NbLTP1/ΔSP-OFP were localized in chloroplasts when we removed the cell wall. These results suggest that NbLTP1 may have a secondary targeting signal. Transient overexpression of NbLTP1 had no effect on BaMV accumulation, but that of NbLTP1/ΔSP significantly increased BaMV expression. NbLTP1 may be a positive regulator of BaMV accumulation especially when its expression is associated with chloroplasts, where BaMV replicates. The mutation was introduced to the predicted phosphorylation site to simulate the phosphorylated status, NbLTP/ΔSP/P(+), which could still assist BaMV accumulation. By contrast, a mutant lacking calmodulin-binding or simulates the phosphorylation-negative status could not support BaMV accumulation. The lipid-binding activity of LTP1 was reported to be associated with calmodulin-binding and phosphorylation, by which the C-terminus functional domain of NbLTP1 may play a critical role in BaMV accumulation.
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Affiliation(s)
- Ling-Ying Chiu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 402, Taiwan; (L.-Y.C.); (I.-H.C.); (Y.-H.H.)
| | - I-Hsuan Chen
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 402, Taiwan; (L.-Y.C.); (I.-H.C.); (Y.-H.H.)
| | - Yau-Heiu Hsu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 402, Taiwan; (L.-Y.C.); (I.-H.C.); (Y.-H.H.)
- Advanced Plant Biotechnology Center, National Chung Hing University, Taichung 402, Taiwan
| | - Ching-Hsiu Tsai
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 402, Taiwan; (L.-Y.C.); (I.-H.C.); (Y.-H.H.)
- Advanced Plant Biotechnology Center, National Chung Hing University, Taichung 402, Taiwan
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8
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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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Niehl A, Heinlein M. Perception of double-stranded RNA in plant antiviral immunity. MOLECULAR PLANT PATHOLOGY 2019; 20:1203-1210. [PMID: 30942534 PMCID: PMC6715784 DOI: 10.1111/mpp.12798] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
RNA silencing and antiviral pattern-triggered immunity (PTI) both rely on recognition of double-stranded (ds)RNAs as defence-inducing signals. While dsRNA recognition by dicer-like proteins during antiviral RNA silencing is thoroughly investigated, the molecular mechanisms involved in dsRNA perception leading to antiviral PTI are just about to be untangled. Parallels to antimicrobial PTI thereby only partially facilitate our view on antiviral PTI. PTI against microbial pathogens involves plasma membrane bound receptors; however, dsRNAs produced during virus infection occur intracellularly. Hence, how dsRNA may be perceived during this immune response is still an open question. In this short review, we describe recent discoveries in PTI signalling upon sensing of microbial patterns and endogenous 'danger' molecules with emphasis on immune signalling-associated subcellular trafficking processes in plants. Based on these studies, we develop different scenarios how dsRNAs could be sensed during antiviral PTI.
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Affiliation(s)
- Annette Niehl
- Julius Kühn‐Institute, Institute for Epidemiology and Pathogen DiagnosticsMesseweg 11‐12D‐38104BraunschweigGermany
| | - Manfred Heinlein
- Université de Strasbourg, CNRS, IBMP UPR235712 rue du Général ZimmerF‐67000StrasbourgFrance
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Budziszewska M, Obrępalska-Stęplowska A. The Role of the Chloroplast in the Replication of Positive-Sense Single-Stranded Plant RNA Viruses. FRONTIERS IN PLANT SCIENCE 2018; 9:1776. [PMID: 30542365 PMCID: PMC6278097 DOI: 10.3389/fpls.2018.01776] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 11/15/2018] [Indexed: 05/20/2023]
Abstract
Positive-sense single-stranded plant RNA viruses are obligate intracellular parasites that infect many agriculturally important crops. Most known plant RNA viruses are characterized by small genomes encoding a limited number of multifunctional viral proteins. Viral pathogens are considered to be absolutely dependent on their hosts, and viruses must recruit numerous host proteins and other factors for genomic RNA replication. Overall, the replication process depends on virus-plant protein-protein, RNA-protein and protein-lipid interactions. Recent publications provide strong evidence for the important role of chloroplasts in viral RNA synthesis. The chloroplast is considered to be a multifunctional organelle responsible for photosynthesis and for the generation of plant defense signaling molecules. High-throughput technologies (genomics and proteomics), and electron microscopy, including three-dimensional tomography, have revealed that several groups of plant RNA viruses utilize chloroplast membranes to assemble viral replication complexes (VRCs). Moreover, some chloroplast-related proteins reportedly interact with both viral proteins and their genomic RNAs and participate in trafficking these molecules to the chloroplast, where replication occurs. Here, we present the current knowledge on the important role of chloroplasts in the viral replication process.
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11
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Pizarro L, Leibman-Markus M, Schuster S, Bar M, Avni A. SlPRA1A/RAB attenuate EIX immune responses via degradation of LeEIX2 pattern recognition receptor. PLANT SIGNALING & BEHAVIOR 2018; 13:e1467689. [PMID: 29944445 PMCID: PMC6103275 DOI: 10.1080/15592324.2018.1467689] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Pattern recognition receptors (PRR) are plasma membrane (PM) proteins that recognize microbe-associated molecular patterns (MAMPs), triggering an immune response. PRR are classified as receptor like kinases (RLKs) or receptor like proteins (RLPs). The PM localization of PRRs, which is crucial for their availability to sense MAMPs, depends on their appropriate trafficking through the endomembrane system. Recently, we have identified SlPRA1A, a prenylated RAB acceptor type-1 (PRA1) from S. lycopersicum, as a regulator of RLP-PRR localization and protein levels. SlPRA1A overexpression strongly decreases RLP-PRR protein levels, particularly those of LeEIX2, redirecting it to the vacuole for degradation. Interestingly, SlPRA1A does not affect RLK-PRRs, indicating its activity to be specific to RLP-PRR systems. As PRA1 proteins stabilize RABs on membranes, promoting RABs activity, we aimed to identify a RAB target of SlPRA1A. Screening of a set of A. thaliana RABs revealed that AtRABA1e is able to mimic SlPRA1A activity. Through live cell imaging, we observed that SlPRA1A enhances AtRABA1e localization on SlPRA1A positive punctuated structures. These results indicate that AtRABA1e is a putative target of SlPRA1, and a co-regulator of LeEIX2 trafficking and degradation.
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Affiliation(s)
- L. Pizarro
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv, Israel
| | - M. Leibman-Markus
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv, Israel
| | - S. Schuster
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv, Israel
| | - M. Bar
- Department of Plant Pathology and Weed Research, ARO, The Volcani Center, Rishon LeZion, Israel
| | - A. Avni
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv, Israel
- CONTACT A. Avni School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv, Israel
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12
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Chen IH, Tsai AY, Huang YP, Wu IF, Cheng SF, Hsu YH, Tsai CH. Nuclear-Encoded Plastidal Carbonic Anhydrase Is Involved in Replication of Bamboo mosaic virus RNA in Nicotiana benthamiana. Front Microbiol 2017; 8:2046. [PMID: 29093706 PMCID: PMC5651272 DOI: 10.3389/fmicb.2017.02046] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 10/06/2017] [Indexed: 01/29/2023] Open
Abstract
On inoculation of Nicotiana benthamiana with Bamboo mosaic virus (BaMV), a gene with downregulated expression was found involved in the infection cycle of BaMV. To uncover how this downregulated gene affects the accumulation of BaMV in plants, we used loss- and gain-of-function experiments. Knockdown of this gene decreased the accumulation of BaMV coat protein to approximately 60% in both plants and protoplasts of N. benthamiana but had no effect on Potato virus X and Cucumber mosaic virus infection. The full-length gene was cloned and revealed as an N. benthamiana nuclear-encoded chloroplast carbonic anhydrase (CA) and so designated NbCA. As compared with the accumulation of BaMV RNAs in NbCA-knockdown protoplasts, both plus- and minus-strand RNAs were reduced. We further fused NbCA with Orange fluorescent protein to confirm its localization in chloroplasts on confocal microscopy. However, transiently expressed NbCA in chloroplasts did not considerably increase BaMV accumulation. The addition of exogenous CA may not have any additive effect on BaMV accumulation because of the natural abundance of CA in chloroplasts. In an in vitro replication assay, the addition of Escherichia coli-expressed NbCA enhanced exogenous template level (re-initiation and elongation) but not endogenous template level (only elongation). These results suggest that NbCA is possibly involved in re-initiation step of BaMV RNA replication. Further analysis indicated that proton concentration could influence the endogenous and exogenous template activities. Hence, our results implied that NbCA could be playing a role in harnessing proton concentration and favoring the replicase with the re-initiation template.
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Affiliation(s)
- I-Hsuan Chen
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - April Y Tsai
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Ying-Ping Huang
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - I-Fan Wu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Shun-Fang Cheng
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Yau-Heiu Hsu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Ching-Hsiu Tsai
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan.,Research Center for Sustainable Energy and Nanotechnology, National Chung Hsing University, Taichung, Taiwan
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13
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Huang YP, Huang YW, Chen IH, Shenkwen LL, Hsu YH, Tsai CH. Plasma membrane-associated cation-binding protein 1-like protein negatively regulates intercellular movement of BaMV. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:4765-4774. [PMID: 28992255 PMCID: PMC5853580 DOI: 10.1093/jxb/erx307] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 08/04/2017] [Indexed: 05/13/2023]
Abstract
To establish a successful infection, a virus needs to replicate and move cell-to-cell efficiently. We investigated whether one of the genes upregulated in Nicotiana benthamiana after Bamboo mosaic virus (BaMV) inoculation was involved in regulating virus movement. We revealed the gene to be a plasma membrane-associated cation-binding protein 1-like protein, designated NbPCaP1L. The expression of NbPCaP1L in N. benthamiana was knocked down using Tobacco rattle virus-based gene silencing and consequently the accumulation of BaMV increased significantly to that of control plants. Further analysis indicated no significant difference in the accumulation of BaMV in NbPCaP1L knockdown and control protoplasts, suggesting NbPCaP1L may affect cell-to-cell movement of BaMV. Using a viral vector expressing green fluorescent protein in the knockdown plants, the mean area of viral focus, as determined by fluorescence, was found to be larger in NbPCaP1L knockdown plants. Orange fluorescence protein (OFP)-fused NbPCaP1L, NbPCaP1L-OFP, was expressed in N. benthamiana and reduced the accumulation of BaMV to 46%. To reveal the possible interaction of viral protein with NbPCaP1L, we performed yeast two-hybrid and co-immunoprecipitation experiments. The results indicated that NbPCaP1L interacted with BaMV replicase. The results also suggested that NbPCaP1L could trap the BaMV movement RNP complex via interaction with the viral replicase in the complex and so restricted viral cell-to-cell movement.
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Affiliation(s)
- Ying-Ping Huang
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 402, Taiwan
| | - Ying-Wen Huang
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 402, Taiwan
| | - I-Hsuan Chen
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 402, Taiwan
| | - Lin-Ling Shenkwen
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 402, Taiwan
| | - Yau-Huei Hsu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 402, Taiwan
| | - Ching-Hsiu Tsai
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 402, Taiwan
- Research Center for Sustainable Energy and Nanotechnology, National Chung Hsing University, Taichung, 402, Taiwan
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14
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Cheng CP. Host Factors Involved in the Intracellular Movement of Bamboo mosaic virus. Front Microbiol 2017; 8:759. [PMID: 28487692 PMCID: PMC5403954 DOI: 10.3389/fmicb.2017.00759] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 04/12/2017] [Indexed: 01/22/2023] Open
Abstract
Viruses move intracellularly to their replication compartments, and the newly synthesized viral complexes are transported to neighboring cells through hijacking of the host endomembrane systems. During these processes, numerous interactions occur among viral proteins, host proteins, and the cytoskeleton system. This review mainly focuses on the plant endomembrane network, which may be utilized by Bamboo mosaic virus (BaMV) to move to its replication compartment, and summarizes the host factors that may be directly involved in delivering BaMV cargoes during intracellular movement. Accumulating evidence indicates that plant endomembrane systems are highly similar but exhibit significant variations from those of other eukaryotic cells. Several Nicotiana benthamiana host proteins have recently been identified to participate in the intracellular movement of BaMV. Chloroplast phosphoglycerate kinase, a host protein transported to chloroplasts, binds to BaMV RNAs and facilitates BaMV replication. NbRABG3f is a small GTPase that plays an essential role in vesicle transportation and is also involved in BaMV replication. These two host proteins may deliver BaMV to the replication compartment. Rab GTPase activation protein 1, which switches Rab GTPase to the inactive conformation, participates in the cell-to-cell movement of BaMV, possibly by trafficking BaMV cargo to neighboring cells after replication. By analyzing the host factors involved in the intracellular movement of BaMV and the current knowledge of plant endomembrane systems, a tentative model for BaMV transport to its replication site within plant cells is proposed.
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Affiliation(s)
- Chi-Ping Cheng
- Department of Life Sciences, Tzu Chi UniversityHualien, Taiwan
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15
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Huang YP, Chen IH, Tsai CH. Host Factors in the Infection Cycle of Bamboo mosaic virus. Front Microbiol 2017; 8:437. [PMID: 28360904 PMCID: PMC5350103 DOI: 10.3389/fmicb.2017.00437] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 03/02/2017] [Indexed: 12/02/2022] Open
Abstract
To complete the infection cycle efficiently, the virus must hijack the host systems in order to benefit for all the steps and has to face all the defense mechanisms from the host. This review involves a discussion of how these positive and negative factors regulate the viral RNA accumulation identified for the Bamboo mosaic virus (BaMV), a single-stranded RNA virus. The genome of BaMV is approximately 6.4 kb in length, encoding five functional polypeptides. To reveal the host factors involved in the infection cycle of BaMV, a few different approaches were taken to screen the candidates. One of the approaches is isolating the viral replicase-associated proteins by co-immunoprecipitation with the transiently expressed tagged viral replicase in plants. Another approach is using the cDNA-amplified fragment length polymorphism technique to screen the differentially expressed genes derived from N. benthamiana plants after infection. The candidates are examined by knocking down the expression in plants using the Tobacco rattle virus-based virus-induced gene silencing technique following BaMV inoculation. The positive or negative regulators could be described as reducing or enhancing the accumulation of BaMV in plants when the expression levels of these proteins are knocked down. The possible roles of these host factors acting on the accumulation of BaMV will be discussed.
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Affiliation(s)
- Ying-Ping Huang
- Graduate Institute of Biotechnology, National Chung Hsing University Taichung, Taiwan
| | - I-Hsuan Chen
- Graduate Institute of Biotechnology, National Chung Hsing University Taichung, Taiwan
| | - Ching-Hsiu Tsai
- Graduate Institute of Biotechnology, National Chung Hsing University Taichung, Taiwan
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16
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Xu K, Nagy PD. Enrichment of Phosphatidylethanolamine in Viral Replication Compartments via Co-opting the Endosomal Rab5 Small GTPase by a Positive-Strand RNA Virus. PLoS Biol 2016; 14:e2000128. [PMID: 27760128 PMCID: PMC5070881 DOI: 10.1371/journal.pbio.2000128] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 09/19/2016] [Indexed: 12/28/2022] Open
Abstract
Positive-strand RNA viruses build extensive membranous replication compartments to support replication and protect the virus from antiviral responses by the host. These viruses require host factors and various lipids to form viral replication complexes (VRCs). The VRCs built by Tomato bushy stunt virus (TBSV) are enriched with phosphatidylethanolamine (PE) through a previously unknown pathway. To unravel the mechanism of PE enrichment within the TBSV replication compartment, in this paper, the authors demonstrate that TBSV co-opts the guanosine triphosphate (GTP)-bound active form of the endosomal Rab5 small GTPase via direct interaction with the viral replication protein. Deletion of Rab5 orthologs in a yeast model host or expression of dominant negative mutants of plant Rab5 greatly decreases TBSV replication and prevents the redistribution of PE to the sites of viral replication. We also show that enrichment of PE in the viral replication compartment is assisted by actin filaments. Interestingly, the closely related Carnation Italian ringspot virus, which replicates on the boundary membrane of mitochondria, uses a similar strategy to the peroxisomal TBSV to hijack the Rab5-positive endosomes into the viral replication compartments. Altogether, usurping the GTP-Rab5–positive endosomes allows TBSV to build a PE-enriched viral replication compartment, which is needed to support peak-level replication. Thus, the Rab family of small GTPases includes critical host factors assisting VRC assembly and genesis of the viral replication compartment. Plants, animals, and humans are threatened by positive-stranded RNA viruses, which are one of the major groups of intracellular pathogens. To support robust virus replication, these viruses subvert intracellular membranes and co-opt host proteins into virus-induced replication compartments. Tomato bushy stunt virus (TBSV) is a model virus used in yeast to dissect the roles of lipids and proteins in virus replication. In this work, the authors show that one of the two TBSV replication proteins interacts with the guanosine triphosphate (GTP)-bound Rab5 small GTPase, which allows the virus to take advantage of phosphatidylethanolamine (PE)-rich endosomes to build viral replication compartments consisting of peroxisomes. Peak level of TBSV replication depends on the co-opted abundant PE-rich Rab5-positive membranes in plants, too.
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Affiliation(s)
- Kai Xu
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Peter D. Nagy
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, United States of America
- * E-mail:
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