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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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Chen R, Yang M, Tu Z, Xie F, Chen J, Luo T, Hu X, Nie B, He C. Eukaryotic translation initiation factor 4E family member nCBP facilitates the accumulation of TGB-encoding viruses by recognizing the viral coat protein in potato and tobacco. FRONTIERS IN PLANT SCIENCE 2022; 13:946873. [PMID: 36003826 PMCID: PMC9393630 DOI: 10.3389/fpls.2022.946873] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 07/11/2022] [Indexed: 06/15/2023]
Abstract
Due to their limited coding capacity, plant viruses have to depend on various host factors for successful infection of the host. Loss of function of these host factors will result in recessively inherited resistance, and therefore, these host factors are also described as susceptibility genes or recessive resistance genes. Most of the identified recessive resistance genes are members of the eukaryotic translation initiation factors 4E family (eIF4E) and its isoforms. Recently, an eIF4E-type gene, novel cap-binding protein (nCBP), was reported to be associated with the infection of several viruses encoding triple gene block proteins (TGBps) in Arabidopsis. Here, we, for the first time, report that the knockdown of nCBP in potato (StnCBP) compromises the accumulation of potato virus S (PVS) but not that of potato virus M (PVM) and potato virus X (PVX), which are three potato viruses encoding TGBps. Further assays demonstrated that StnCBP interacts with the coat proteins (CPs) of PVS and PVM but not with that of PVX, and substitution of PVS CP in the PVS infectious clone by PVM CP recovered the virus infection in StnCBP-silenced transgenic plants, suggesting that the recognition of PVS CP is crucial for StnCBP-mediated recessive resistance to PVS. Moreover, the knockdown of nCBP in Nicotiana benthamiana (NbnCBP) by virus-induced gene silencing suppressed PVX accumulation but not PVM, while NbnCBP interacted with the CPs of both PVX and PVM. Our results indicate that the nCBP orthologues in potato and tobacco have conserved function as in Arabidopsis in terms of recessive resistance against TGB-encoding viruses, and the interaction between nCBP and the CP of TGB-encoding virus is necessary but not sufficient to determine the function of nCBP as a susceptibility gene.
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Affiliation(s)
- Ruhao Chen
- ERC for Germplasm Innovation and New Variety Breeding of Horticultural Crops, Key Laboratory for Vegetable Biology of Hunan Province, Hunan Agricultural University, Changsha, China
- Key Laboratory of Potato Biology and Biotechnology (HZAU), Ministry of Agriculture and Rural Affairs, Key Laboratory of Horticultural Plant Biology (HZAU), Ministry of Education, Huazhong Agricultural University, Wuhan, China
| | - Manhua Yang
- Key Laboratory of Potato Biology and Biotechnology (HZAU), Ministry of Agriculture and Rural Affairs, Key Laboratory of Horticultural Plant Biology (HZAU), Ministry of Education, Huazhong Agricultural University, Wuhan, China
| | - Zhen Tu
- Key Laboratory of Potato Biology and Biotechnology (HZAU), Ministry of Agriculture and Rural Affairs, Key Laboratory of Horticultural Plant Biology (HZAU), Ministry of Education, Huazhong Agricultural University, Wuhan, China
| | - Fangru Xie
- Key Laboratory of Potato Biology and Biotechnology (HZAU), Ministry of Agriculture and Rural Affairs, Key Laboratory of Horticultural Plant Biology (HZAU), Ministry of Education, Huazhong Agricultural University, Wuhan, China
| | - Jiaru Chen
- Key Laboratory of Potato Biology and Biotechnology (HZAU), Ministry of Agriculture and Rural Affairs, Key Laboratory of Horticultural Plant Biology (HZAU), Ministry of Education, Huazhong Agricultural University, Wuhan, China
| | - Tao Luo
- Key Laboratory of Potato Biology and Biotechnology (HZAU), Ministry of Agriculture and Rural Affairs, Key Laboratory of Horticultural Plant Biology (HZAU), Ministry of Education, Huazhong Agricultural University, Wuhan, China
| | - Xinxi Hu
- ERC for Germplasm Innovation and New Variety Breeding of Horticultural Crops, Key Laboratory for Vegetable Biology of Hunan Province, Hunan Agricultural University, Changsha, China
| | - Bihua Nie
- Key Laboratory of Potato Biology and Biotechnology (HZAU), Ministry of Agriculture and Rural Affairs, Key Laboratory of Horticultural Plant Biology (HZAU), Ministry of Education, Huazhong Agricultural University, Wuhan, China
| | - Changzheng He
- ERC for Germplasm Innovation and New Variety Breeding of Horticultural Crops, Key Laboratory for Vegetable Biology of Hunan Province, Hunan Agricultural University, Changsha, China
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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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Chen I, Chen X, Chiu G, Huang Y, Hsu Y, Tsai C. The function of chloroplast ferredoxin-NADP + oxidoreductase positively regulates the accumulation of bamboo mosaic virus in Nicotiana benthamiana. MOLECULAR PLANT PATHOLOGY 2022; 23:503-515. [PMID: 34918877 PMCID: PMC8916203 DOI: 10.1111/mpp.13174] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 11/17/2021] [Accepted: 11/21/2021] [Indexed: 05/08/2023]
Abstract
A gene down-regulated in Nicotiana benthamiana after bamboo mosaic virus (BaMV) infection had high identity to the nuclear-encoded chloroplast ferredoxin NADP+ oxidoreductase gene (NbFNR). NbFNR is a flavoenzyme involved in the photosynthesis electron transport chain, catalysing the conversion of NADP+ into NADPH. To investigate whether NbFNR is involved in BaMV infection, we used virus-induced gene silencing to reduce the expression of NbFNR in leaves and protoplasts. After BaMV inoculation, the accumulation of BaMV coat protein and RNA was significantly reduced. The transient expression of NbFNR fused with orange fluorescent protein (OFP) localized in the chloroplasts and elevated the level of BaMV coat protein. These results suggest that NbFNR could play a positive role in regulating BaMV accumulation. Expressing a mutant that failed to translocate to the chloroplast did not assist in BaMV accumulation. Another mutant with a catalytic site mutation could support BaMV accumulation to some extent, but accumulation was significantly lower than that of the wild type. In an in vitro replication assay, the replicase complex with FNR inhibitor, heparin, the RdRp activity was reduced. Furthermore, BaMV replicase was revealed to interact with NbFNR in yeast two-hybrid and co-immunoprecipitation experiments. Overall, these results suggest that NbFNR localized in the chloroplast with functional activity could efficiently assist BaMV accumulation.
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Affiliation(s)
- I‐Hsuan Chen
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichungTaiwan
| | - Xiang‐Yu Chen
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichungTaiwan
| | - Guan‐Zhi Chiu
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichungTaiwan
| | - Ying‐Ping Huang
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichungTaiwan
| | - Yau‐Heiu Hsu
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichungTaiwan
- Advaced Plant Biotechnology CenterNational Chung Hsing UniversityTaichungTaiwan
| | - Ching‐Hsiu Tsai
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichungTaiwan
- Advaced Plant Biotechnology CenterNational Chung Hsing UniversityTaichungTaiwan
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Huang YW, Lee CW, Lin NS, Cuong HV, Hu CC, Hsu YH. First Report of Distinct Bamboo mosaic virus (BaMV) Isolates Infecting Bambusa funghomii in Vietnam and the Identification of a Highly Variable Region in the BaMV Genome. Viruses 2022; 14:698. [PMID: 35458428 PMCID: PMC9032891 DOI: 10.3390/v14040698] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 03/17/2022] [Accepted: 03/24/2022] [Indexed: 02/04/2023] Open
Abstract
New isolates of the Bamboo mosaic virus (BaMV) were identified in Bambusa funghomii bamboo in Vietnam. Sequence analyses revealed that the Vietnam isolates are distinct from all known BaMV strains, sharing the highest sequence identities (about 77%) with the Yoshi isolates reported in California, USA. Unique satellite RNAs were also found to be associated with the BaMV Vietnam isolates. A possible recombination event was detected in the genome of BaMV-VN2. A highly variable region was identified in the ORF1 gene, in between the methyl transferase domain and helicase domain. These results revealed the presence of unique BaMV isolates in an additional bamboo species in one more country, Vietnam, and provided evidence in support of the possible involvement of environmental or host factors in the diversification and evolution of BaMV.
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Affiliation(s)
- Ying-Wen Huang
- Graduate Institute of Biotechnology, National Chung Hsing University, 250 Kuo-Kuang Rd, Taichung 40227, Taiwan; (Y.-W.H.); (C.-W.L.)
- Advanced Plant Biotechnology Center, National Chung Hsing University, Taichung 40227, Taiwan
| | - Chin-Wei Lee
- Graduate Institute of Biotechnology, National Chung Hsing University, 250 Kuo-Kuang Rd, Taichung 40227, Taiwan; (Y.-W.H.); (C.-W.L.)
| | - Na-Sheng Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan;
| | - Ha Viet Cuong
- Department of Plant Pathology, Research Center for Tropic Plant Diseases, Vietnam National University of Agriculture, Hanoi 100915, Vietnam;
| | - Chung-Chi Hu
- Graduate Institute of Biotechnology, National Chung Hsing University, 250 Kuo-Kuang Rd, Taichung 40227, Taiwan; (Y.-W.H.); (C.-W.L.)
- Advanced Plant Biotechnology Center, National Chung Hsing University, Taichung 40227, Taiwan
| | - Yau-Heiu Hsu
- Graduate Institute of Biotechnology, National Chung Hsing University, 250 Kuo-Kuang Rd, Taichung 40227, Taiwan; (Y.-W.H.); (C.-W.L.)
- Advanced Plant Biotechnology Center, National Chung Hsing University, Taichung 40227, Taiwan
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Lin KY, Wu SY, Hsu YH, Lin NS. MiR398-regulated antioxidants contribute to Bamboo mosaic virus accumulation and symptom manifestation. PLANT PHYSIOLOGY 2022; 188:593-607. [PMID: 34695209 PMCID: PMC9040666 DOI: 10.1093/plphys/kiab451] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 08/27/2021] [Indexed: 06/13/2023]
Abstract
Virus infections that cause mosaic or mottling in leaves commonly also induce increased levels of reactive oxygen species (ROS). However, how ROS contributes to symptoms is less well documented. Bamboo mosaic virus (BaMV) causes chlorotic mosaic symptoms in both Brachypodium distachyon and Nicotiana benthamiana. The BaMV △CPN35 mutant with an N-terminal deletion of its coat protein gene exhibits asymptomatic infection independently of virus titer. Histochemical staining of ROS in mock-, BaMV-, and BaMV△CPN35-infected leaves revealed that hydrogen peroxide (H2O2) accumulated solely in BaMV-induced chlorotic spots. Moreover, exogenous H2O2 treatment enhanced yellowish chlorosis in BaMV-infected leaves. Both BaMV and BaMV△CPN35 infection could induce the expression of Cu/Zu superoxide dismutase (CSD) antioxidants at messenger RNA and protein level. However, BaMV triggered the abundant accumulation of full-length NbCSD2 preprotein (prNbCSD2, without transit peptide cleavage), whereas BaMV△CPN35 induced a truncated prNbCSD2. Confocal microscopy showed that majority of NbCSD2-green fluorescent protein (GFP) predominantly localized in the cytosol upon BaMV infection, but BaMV△CPN35 infection tended to cause NbCSD2-GFP to remain in chloroplasts. By 5'-RNA ligase-mediated rapid amplification of cDNA ends, we validated CSDs are the targets of miR398 in vivo. Furthermore, BaMV infection increased the level of miR398, while the level of BaMV titer was regulated positively by miR398 but negatively by CSD2. In contrast, overexpression of cytosolic form NbCSD2, impairing the transport into chloroplasts, greatly enhanced BaMV accumulation. Taken together, our results indicate that induction of miR398 by BaMV infection may facilitate viral titer accumulation, and cytosolic prNbCSD2 induction may contribute to H2O2 accumulation, resulting in the development of BaMV chlorotic symptoms in plants.
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Affiliation(s)
- Kuan-Yu Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Su-Yao Wu
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Yau-Heiu Hsu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 40227, Taiwan
| | - Na-Sheng Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
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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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Alazem M, He MH, Chang CH, Cheng N, Lin NS. Disrupting the Homeostasis of High Mobility Group Protein Promotes the Systemic Movement of Bamboo mosaic virus. FRONTIERS IN PLANT SCIENCE 2020; 11:597665. [PMID: 33424893 PMCID: PMC7793662 DOI: 10.3389/fpls.2020.597665] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 11/11/2020] [Indexed: 05/21/2023]
Abstract
Viruses hijack various organelles and machineries for their replication and movement. Ever more lines of evidence indicate that specific nuclear factors are involved in systemic trafficking of several viruses. However, how such factors regulate viral systemic movement remains unclear. Here, we identify a novel role for Nicotiana benthamiana high mobility group nucleoprotein (NbHMG1/2a) in virus movement. Although infection of N. benthamiana with Bamboo mosaic virus (BaMV) decreased NbHMG1/2a expression levels, nuclear-localized NbHMG1/2a protein was shuttled out of the nucleus into cytoplasm upon BaMV infection. NbHMG1/2a knockdown or even overexpression did not affect BaMV accumulation in inoculated leaves, but it did enhance systemic movement of the virus. Interestingly, the positive regulator Rap-GTPase activation protein 1 was highly upregulated upon infection with BaMV, whereas the negative regulator thioredoxin h protein was greatly reduced, no matter if NbHMG1a/2a was silenced or overexpressed. Our findings indicate that NbHMG1/2a may have a role in plant defense responses. Once its homeostasis is disrupted, expression of relevant host factors may be perturbed that, in turn, facilitates BaMV systemic movement.
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Affiliation(s)
| | | | | | | | - Na-Sheng Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 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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Lee CC, Wang JW, Leu WM, Huang YT, Huang YW, Hsu YH, Meng M. Proliferating Cell Nuclear Antigen Suppresses RNA Replication of Bamboo Mosaic Virus through an Interaction with the Viral Genome. J Virol 2019; 93:e00961-19. [PMID: 31511381 PMCID: PMC6819918 DOI: 10.1128/jvi.00961-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 08/30/2019] [Indexed: 11/20/2022] Open
Abstract
Bamboo mosaic virus (BaMV), a member of the Potexvirus genus, has a monopartite positive-strand RNA genome on which five open reading frames (ORFs) are organized. ORF1 encodes a 155-kDa nonstructural protein (REPBaMV) that plays a core function in replication/transcription of the viral genome. To find out cellular factors modulating the replication efficiency of BaMV, a putative REPBaMV-associated protein complex from Nicotiana benthamiana leaf was isolated on an SDS-PAGE gel, and a few proteins preferentially associated with REPBaMV were identified by tandem mass spectrometry. Among them, proliferating cell nuclear antigen (PCNA) was particularly noted. Overexpression of PCNA strongly suppressed the accumulation of BaMV coat protein and RNAs in leaf protoplasts. In addition, PCNA exhibited an inhibitory effect on BaMV polymerase activity. A pulldown assay confirmed a binding capability of PCNA toward BaMV genomic RNA. Mutations at D41 or F114 residues, which are critical for PCNA to function in nuclear DNA replication and repair, disabled PCNA from binding BaMV genomic RNA as well as suppressing BaMV replication. This suggests that PCNA bound to the viral RNA may interfere with the formation of a potent replication complex or block the replication process. Interestingly, BaMV is almost invisible in the newly emerging leaves where PCNA is actively expressed. Accordingly, PCNA is probably one of the factors restricting the proliferation of BaMV in young leaves. Foxtail mosaic virus and Potato virus X were also suppressed by PCNA in the protoplast experiment, suggesting a general inhibitory effect of PCNA on the replication of potexviruses.IMPORTANCE Knowing the dynamic interplay between plant RNA viruses and their host is a basic step toward first understanding how the viruses survive the plant defense mechanisms and second gaining knowledge of pathogenic control in the field. This study found that plant proliferating cell nuclear antigen (PCNA) imposes a strong inhibition on the replication of several potexviruses, including Bamboo mosaic virus, Foxtail mosaic virus, and Potato virus X Based on the tests on Bamboo mosaic virus, PCNA is able to bind the viral genomic RNA, and this binding is a prerequisite for the protein to suppress the virus replication. This study also suggests that PCNA plays an important role in restricting the proliferation of potexviruses in the rapidly dividing tissues of plants.
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Affiliation(s)
- Cheng-Cheng Lee
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Jhih-Wei Wang
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Wei-Ming Leu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Yu-Ting Huang
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Ying-Wen Huang
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Yau-Heiu Hsu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Menghsiao Meng
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
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Huang YP, Huang YW, Hsiao YJ, Li SC, Hsu YH, Tsai CH. Autophagy is involved in assisting the replication of Bamboo mosaic virus in Nicotiana benthamiana. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:4657-4670. [PMID: 31552430 PMCID: PMC6760330 DOI: 10.1093/jxb/erz244] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Indexed: 05/20/2023]
Abstract
Autophagy plays a critical role in plants under biotic stress, including the response to pathogen infection. We investigated whether autophagy-related genes (ATGs) are involved in infection with Bamboo mosaic virus (BaMV), a single-stranded positive-sense RNA virus. Initially, we observed that BaMV infection in Nicotiana benthamiana leaves upregulated the expression of ATGs but did not trigger cell death. The induction of ATGs, which possibly triggers autophagy, increased rather than diminished BaMV accumulation in the leaves, as revealed by gene knockdown and transient expression experiments. Furthermore, the inhibitor 3-methyladenine blocked autophagosome formation and the autophagy inducer rapamycin, which negatively and positively affected BaMV accumulation, respectively. Pull-down experiments with an antibody against orange fluorescent protein (OFP)-NbATG8f, an autophagosome marker protein, showed that both plus- and minus-sense BaMV RNAs could associate with NbATG8f. Confocal microscopy revealed that ATG8f-enriched vesicles possibly derived from chloroplasts contained both the BaMV viral RNA and its replicase. Thus, BaMV infection may induce the expression of ATGs possibly via autophagy to selectively engulf a portion of viral RNA-containing chloroplast. Virus-induced vesicles enriched with ATG8f could provide an alternative site for viral RNA replication or a shelter from the host silencing mechanism.
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Affiliation(s)
- Ying-Ping Huang
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Ying-Wen Huang
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Yung-Jen Hsiao
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Siou-Cen Li
- 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
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12
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Lee C, Wu Y, Hsueh C, Huang Y, Hsu Y, Meng M. Mitogen-activated protein kinase phosphatase 1 reduces the replication efficiency of Bamboo mosaic virus in Nicotiana benthamiana. MOLECULAR PLANT PATHOLOGY 2018; 19:2319-2332. [PMID: 29806182 PMCID: PMC6638022 DOI: 10.1111/mpp.12701] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 04/22/2018] [Accepted: 05/20/2018] [Indexed: 06/08/2023]
Abstract
In plants, the mitogen-activated protein kinase (MAPK) cascades are the central signaling pathways of the complicated defense network triggered by the perception of pathogen-associated molecular patterns to repel pathogens. The Arabidopsis thaliana MAPK phosphatase 1 (AtMKP1) negatively regulates the activation of MAPKs. Recently, the AtMKP1 homolog of Nicotiana benthamiana (NbMKP1) was found in association with the Bamboo mosaic virus (BaMV) replication complex. This study aimed to investigate the role of NbMKP1 in BaMV multiplication in N. benthamiana. Silencing of NbMKP1 increased accumulations of the BaMV-encoded proteins and the viral genomic RNA, although the same condition reduced the infectivity of Pseudomonas syringae pv. tomato DC3000 in N. benthamiana. On the other hand, overexpression of NbMKP1 decreased the BaMV coat protein accumulation in a phosphatase activity-dependent manner in protoplasts. NbMKP1 also negatively affected the in vitro RNA polymerase activity of the BaMV replication complex. Collectively, the activity of NbMKP1 seems to reduce BaMV multiplication, inconsistent with the negatively regulatory role of MKP1 in MAPK cascades in terms of warding off fungal and bacterial invasion. In addition, silencing of NbMKP1 increased the accumulation of Foxtail mosaic virus but decreased Potato virus X. The discrepant effects exerted by NbMKP1 on different pathogens foresee the difficulty to develop plants with broad-spectrum resistance through genetically manipulating a single player in MAPK cascades.
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Affiliation(s)
- Cheng‐Cheng Lee
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichungTaiwan, ROC40227
| | - Yi‐Jhen Wu
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichungTaiwan, ROC40227
| | - Chia‐Hsin Hsueh
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichungTaiwan, ROC40227
| | - Yu‐Ting Huang
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichungTaiwan, ROC40227
| | - Yau‐Heiu Hsu
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichungTaiwan, ROC40227
| | - Menghsiao Meng
- Graduate Institute of BiotechnologyNational Chung Hsing UniversityTaichungTaiwan, ROC40227
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13
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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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14
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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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15
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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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16
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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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17
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Lin KY, Lin NS. Interfering Satellite RNAs of Bamboo mosaic virus. Front Microbiol 2017; 8:787. [PMID: 28522996 PMCID: PMC5415622 DOI: 10.3389/fmicb.2017.00787] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 04/18/2017] [Indexed: 11/13/2022] Open
Abstract
Satellite RNAs (satRNAs) are sub-viral agents that may interact with their cognate helper virus (HV) and host plant synergistically and/or antagonistically. SatRNAs totally depend on the HV for replication, so satRNAs and HV usually evolve similar secondary or tertiary RNA structures that are recognized by a replication complex, although satRNAs and HV do not share an appreciable sequence homology. The satRNAs of Bamboo mosaic virus (satBaMV), the only satRNAs of the genus Potexvirus, have become one of the models of how satRNAs can modulate HV replication and virus-induced symptoms. In this review, we summarize the molecular mechanisms underlying the interaction of interfering satBaMV and BaMV. Like other satRNAs, satBaMV mimics the secondary structures of 5'- and 3'-untranslated regions (UTRs) of BaMV as a molecular pretender. However, a conserved apical hairpin stem loop (AHSL) in the 5'-UTR of satBaMV was found as the key determinant for downregulating BaMV replication. In particular, two unique nucleotides (C60 and C83) in the AHSL of satBaMVs determine the satBaMV interference ability by competing for the replication machinery. Thus, transgenic plants expressing interfering satBaMV could confer resistance to BaMV, and interfering satBaMV could be used as biological-control agent. Unlike two major anti-viral mechanisms, RNA silencing and salicylic acid-mediated immunity, our findings in plants by in vivo competition assay and RNA deep sequencing suggested replication competition is involved in this transgenic satBaMV-mediated BaMV interference. We propose how a single nucleotide of satBaMV can make a great change in BaMV pathogenicity and the underlying mechanism.
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Affiliation(s)
- Kuan-Yu Lin
- Institute of Plant and Microbial Biology, Academia SinicaTaipei, Taiwan
| | - Na-Sheng Lin
- Institute of Plant and Microbial Biology, Academia SinicaTaipei, Taiwan
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18
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Meng M, Lee CC. Function and Structural Organization of the Replication Protein of Bamboo mosaic virus. Front Microbiol 2017; 8:522. [PMID: 28400766 PMCID: PMC5368238 DOI: 10.3389/fmicb.2017.00522] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 03/13/2017] [Indexed: 12/17/2022] Open
Abstract
The genus Potexvirus is one of the eight genera belonging to the family Alphaflexiviridae according to the Virus Taxonomy 2015 released by International Committee on Taxonomy of Viruses (www.ictvonline.org/index.asp). Currently, the genus contains 35 known species including many agricultural important viruses, e.g., Potato virus X (PVX). Members of this genus are characterized by flexuous, filamentous virions of 13 nm in diameter and 470-580 nm in length. A potexvirus has a monopartite positive-strand RNA genome, encoding five open-reading frames (ORFs), with a cap structure at the 5' end and a poly(A) tail at the 3' end. Besides PVX, Bamboo mosaic virus (BaMV) is another potexvirus that has received intensive attention due to the wealth of knowledge on the molecular biology of the virus. In this review, we discuss the enzymatic activities associated with each of the functional domains of the BaMV replication protein, a 155-kDa polypeptide encoded by ORF1. The unique cap formation mechanism, which may be conserved across the alphavirus superfamily, is particularly addressed. The recently identified interactions between the replication protein and the plant host factors are also described.
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Affiliation(s)
- Menghsiao Meng
- Graduate Institute of Biotechnology, National Chung Hsing University Taichung, Taiwan
| | - Cheng-Cheng Lee
- Graduate Institute of Biotechnology, National Chung Hsing University Taichung, Taiwan
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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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20
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Alazem M, Lin NS. Antiviral Roles of Abscisic Acid in Plants. FRONTIERS IN PLANT SCIENCE 2017; 8:1760. [PMID: 29075279 PMCID: PMC5641568 DOI: 10.3389/fpls.2017.01760] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 09/26/2017] [Indexed: 05/18/2023]
Abstract
Abscisic acid (ABA) is a key hormone involved in tuning responses to several abiotic stresses and also has remarkable impacts on plant defense against various pathogens. The roles of ABA in plant defense against bacteria and fungi are multifaceted, inducing or reducing defense responses depending on its time of action. However, ABA induces different resistance mechanisms to viruses regardless of the induction time. Recent studies have linked ABA to the antiviral silencing pathway, which interferes with virus accumulation, and the micro RNA (miRNA) pathway through which ABA affects the maturation and stability of miRNAs. ABA also induces callose deposition at plasmodesmata, a mechanism that limits viral cell-to-cell movement. Bamboo mosaic virus (BaMV) is a member of the potexvirus group and is one of the most studied viruses in terms of the effects of ABA on its accumulation and resistance. In this review, we summarize how ABA interferes with the accumulation and movement of BaMV and other viruses. We also highlight aspects of ABA that may have an effect on other types of resistance and that require further investigation.
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21
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Huang YP, Jhuo JH, Tsai MS, Tsai CH, Chen HC, Lin NS, Hsu YH, Cheng CP. NbRABG3f, a member of Rab GTPase, is involved in Bamboo mosaic virus infection in Nicotiana benthamiana. MOLECULAR PLANT PATHOLOGY 2016; 17:714-26. [PMID: 26416342 PMCID: PMC6638505 DOI: 10.1111/mpp.12325] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The screening of differentially expressed genes in plants after pathogen infection can uncover the potential host factors required for the pathogens. In this study, an up-regulated gene was identified and cloned from Nicotiana benthamiana plants after Bamboo mosaic virus (BaMV) inoculation. The up-regulated gene was identified as a member of the Rab small guanosine triphosphatase (GTPase) family, and was designated as NbRABG3f according to its in silico translated product with high identity to that of RABG3f of tomato. Knocking down the expression of NbRABG3f using a virus-induced gene silencing technique in a protoplast inoculation assay significantly reduced the accumulation of BaMV. A transiently expressed NbRABG3f protein in N. benthamiana plants followed by BaMV inoculation enhanced the accumulation of BaMV to approximately 150%. Mutants that had the catalytic site mutation (NbRABG3f/T22N) or had lost their membrane-targeting capability (NbRABG3f/ΔC3) failed to facilitate the accumulation of BaMV in plants. Because the Rab GTPase is responsible for vesicle trafficking between organelles, a mutant with a fixed guanosine diphosphate form was used to identify the donor compartment. The use of green fluorescent protein (GFP) fusion revealed that GFP-NbRABG3f/T22N clearly co-localized with the Golgi marker. In conclusion, BaMV may use NbRABG3f to form vesicles derived from the Golgi membrane for intracellular trafficking to deliver unidentified factors to its replication site; thus, both GTPase activity and membrane-targeting ability are crucial for BaMV accumulation at the cell level.
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Affiliation(s)
- Ying-Ping Huang
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 402, Taiwan
| | - Jia-Hua Jhuo
- Department of Life Sciences, Tzu Chi University, Hualien, 970, Taiwan
| | - Meng-Shan Tsai
- Department of Life Sciences, Tzu Chi University, Hualien, 970, Taiwan
| | - Ching-Hsiu Tsai
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 402, Taiwan
| | - Hong-Chi Chen
- Department of Life Sciences, Tzu Chi University, Hualien, 970, Taiwan
| | - Na-Sheng Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Nankang Taipei, 115, Taiwan
| | - Yau-Heiu Hsu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 402, Taiwan
| | - Chi-Ping Cheng
- Department of Life Sciences, Tzu Chi University, Hualien, 970, Taiwan
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22
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Lee CC, Lin TL, Lin JW, Han YT, Huang YT, Hsu YH, Meng M. Promotion of Bamboo Mosaic Virus Accumulation in Nicotiana benthamiana by 5'→3' Exonuclease NbXRN4. Front Microbiol 2016; 6:1508. [PMID: 26779163 PMCID: PMC4702010 DOI: 10.3389/fmicb.2015.01508] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 12/14/2015] [Indexed: 12/11/2022] Open
Abstract
Bamboo mosaic virus (BaMV) has a 6.4-kb (+) sense RNA genome with a 5' cap and a 3' poly(A) tail. ORF1 of this potexvirus encodes a 155-kDa replication protein responsible for the viral RNA replication/transcription and 5' cap formation. To learn more about the replication complex of BaMV, a protein preparation enriched in the 155-kDa replication protein was obtained from Nicotiana benthamiana by a protocol involving agroinfiltration and immunoprecipitation. Subsequent analysis by SDS-PAGE and mass spectrometry identified a handful of host proteins that may participate in the viral replication. Among them, the cytoplasmic exoribonuclease NbXRN4 particularly caught our attention. NbXRN4 has been shown to have an antiviral activity against Tomato bushy stunt virus and Tomato mosaic virus. In Arabidopsis, the enzyme could reduce RNAi- and miRNA-mediated RNA decay. This study found that downregulation of NbXRN4 greatly decreased BaMV accumulation, while overexpression of NbXRN4 resulted in an opposite effect. Mutations at the catalytically essential residues abolished the function of NbXRN4 in the increase of BaMV accumulation. Nonetheless, NbXRN4 was still able to promote BaMV accumulation in the presence of the RNA silencing suppressor P19. In summary, the replication efficiency of BaMV may be improved by the exoribonuclease activity of NbXRN4.
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Affiliation(s)
- Cheng-Cheng Lee
- Graduate Institute of Biotechnology, National Chung Hsing University Taichung, Taiwan
| | - Tzu-Ling Lin
- Graduate Institute of Biotechnology, National Chung Hsing UniversityTaichung, Taiwan; Division of Medicine Centre for Nephrology, University College LondonLondon, UK
| | - Jhe-Wei Lin
- Graduate Institute of Biotechnology, National Chung Hsing University Taichung, Taiwan
| | - Yu-Tsung Han
- Graduate Institute of Biotechnology, National Chung Hsing University Taichung, Taiwan
| | - Yu-Ting Huang
- Graduate Institute of Biotechnology, National Chung Hsing University Taichung, Taiwan
| | - Yau-Heiu Hsu
- Graduate Institute of Biotechnology, National Chung Hsing University Taichung, Taiwan
| | - Menghsiao Meng
- Graduate Institute of Biotechnology, National Chung Hsing University Taichung, Taiwan
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Liou MR, Hu CC, Chou YL, Chang BY, Lin NS, Hsu YH. Viral elements and host cellular proteins in intercellular movement of Bamboo mosaic virus. Curr Opin Virol 2015; 12:99-108. [PMID: 25951346 DOI: 10.1016/j.coviro.2015.04.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 04/15/2015] [Accepted: 04/17/2015] [Indexed: 12/23/2022]
Abstract
As a member of the genus Potexvirus, Bamboo mosaic virus (BaMV) also belongs to the plant viruses that encode triple gene block proteins (TGBps) for intercellular movement within the host plants. Recent studies of the movement mechanisms of BaMV have revealed similarities and differences between BaMV and other potexviruses. This review focuses on the general aspects of viral and host elements involved in BaMV movement, the interactions among these elements, and the possible pathways for intra- and intercellular trafficking of BaMV. Major features of BaMV trafficking that have not been demonstrated in other potexviruses include: (i) the involvement of replicase, (ii) fine regulation by coat protein phosphorylation, (iii) the key roles played by TGBp3, (iv) the use of virions as the major transported form, and (v) the involvement of specific host factors, such as Ser/Thr kinase-like protein of Nicotiana benthamiana. We also highlight areas for future study that will provide a more comprehensive understanding of the detailed interactions among viral movement proteins and host factors, as well as the regulatory mechanisms of virus movement. Finally, a model based on the current knowledge is proposed to depict the diverse abilities of BaMV to utilize a wide range of mechanisms for efficient intercellular movement.
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Affiliation(s)
- Ming-Ru Liou
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 40227, Taiwan
| | - Chung-Chi Hu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 40227, Taiwan
| | - Yuan-Lin Chou
- Institute of Biochemistry, National Chung Hsing University, Taichung 40227, Taiwan
| | - Ban-Yang Chang
- Institute of Biochemistry, National Chung Hsing University, Taichung 40227, Taiwan
| | - Na-Sheng Lin
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 40227, Taiwan; Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Yau-Heiu Hsu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 40227, Taiwan.
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Hung CJ, Huang YW, Liou MR, Lee YC, Lin NS, Meng M, Tsai CH, Hu CC, Hsu YH. Phosphorylation of coat protein by protein kinase CK2 regulates cell-to-cell movement of Bamboo mosaic virus through modulating RNA binding. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2014; 27:1211-25. [PMID: 25025779 DOI: 10.1094/mpmi-04-14-0112-r] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
In this study, we investigated the fine regulation of cell-to-cell movement of Bamboo mosaic virus (BaMV). We report that the coat protein (CP) of BaMV is phosphorylated in planta at position serine 241 (S241), in a process involving Nicotiana benthamiana casein kinase 2α (NbCK2α). BaMV CP and NbCK2α colocalize at the plasmodesmata, suggesting that phosphorylation of BaMV may be involved in its movement. S241 was mutated to examine the effects of temporal and spatial dysregulation of phosphorylation on i) the interactions between CP and viral RNA and ii) the regulation of cell-to-cell movement. Replacement of S241 with alanine did not affect RNA binding affinity but moderately impaired cell-to-cell movement. A negative charge at position 241 reduced the ability of CP to bind RNA and severely interfered with cell-to-cell movement. Deletion of residues 240 to 242 increased the affinity of CP to viral RNA and dramatically impaired cell-to-cell movement. A threonine at position 241 changed the binding preference of CP toward genomic RNA and inhibited cell-to-cell movement. Together, these results reveal a fine regulatory mechanism for the cell-to-cell movement of BaMV, which involves the modulation of RNA binding affinity through appropriate phosphorylation of CP by NbCK2α.
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Park MR, Jeong RD, Kim KH. Understanding the intracellular trafficking and intercellular transport of potexviruses in their host plants. FRONTIERS IN PLANT SCIENCE 2014; 5:60. [PMID: 24672528 PMCID: PMC3957223 DOI: 10.3389/fpls.2014.00060] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 02/06/2014] [Indexed: 05/22/2023]
Abstract
The movement of potexviruses through the cytoplasm to plasmodesmata (PD) and through PD to adjacent cells depends on the viral and host cellular proteins. Potexviruses encode three movement proteins [referred to as the triple gene block (TGB1-3)]. TGB1 protein moves cell-to-cell through PD and requires TGB2 and TGB3, which are endoplasmic reticulum (ER)-located proteins. TGB3 protein directs the movement of the ER-derived vesicles induced by TGB2 protein from the perinuclear ER to the cortical ER. TGB2 protein physically interacts with TGB3 protein in a membrane-associated form and also interacts with either coat protein (CP) or TGB1 protein at the ER network. Recent studies indicate that potexvirus movement involves the interaction between TGB proteins and CP with host proteins including membrane rafts. A group of host cellular membrane raft proteins, remorins, can serve as a counteracting membrane platform for viral ribonucleoprotein (RNP) docking and can thereby inhibit viral movement. The CP, which is a component of the RNP movement complex, is also critical for viral cell-to-cell movement through the PD. Interactions between TGB1 protein and/or the CP subunit with the 5'-terminus of genomic RNA [viral RNA (vRNA)] form RNP movement complexes and direct the movement of vRNAs through the PD. Recent studies show that tobacco proteins such as NbMPB2C or NbDnaJ-like proteins interact with the stem-loop 1 RNA located at the 5'-terminus of Potato virus X vRNA and regulate intracellular as well as intercellular movement. Although several host proteins that interact with vRNAs or viral proteins and that are crucial for vRNA transport have been screened and characterized, additional host proteins and details of viral movement remain to be characterized. In this review, we describe recent progress in understanding potexvirus movement within and between cells and how such movement is affected by interactions between vRNA/proteins and host proteins.
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Affiliation(s)
- Mi-Ri Park
- Department of Agricultural Biotechnology, Seoul National UniversitySeoul, South Korea
- Plant Genomics and Breeding Institute, Seoul National UniversitySeoul, South Korea
- Research Institute for Agriculture and Life Sciences, Seoul National UniversitySeoul, South Korea
| | - Rae-Dong Jeong
- Advanced Radiation Technology Institute, Korea Atomic Energy Research InstituteJeongeup, South Korea
| | - Kook-Hyung Kim
- Department of Agricultural Biotechnology, Seoul National UniversitySeoul, South Korea
- Plant Genomics and Breeding Institute, Seoul National UniversitySeoul, South Korea
- Research Institute for Agriculture and Life Sciences, Seoul National UniversitySeoul, South Korea
- *Correspondence: Kook-Hyung Kim, Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, South Korea e-mail:
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Huang YP, Chen JS, Hsu YH, Tsai CH. A putative Rab-GTPase activation protein from Nicotiana benthamiana is important for Bamboo mosaic virus intercellular movement. Virology 2013; 447:292-9. [PMID: 24210126 DOI: 10.1016/j.virol.2013.09.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Revised: 08/03/2013] [Accepted: 09/21/2013] [Indexed: 12/31/2022]
Abstract
The cDNA-amplified fragment length polymorphism technique was applied to isolate the differentially expressed genes during Bamboo mosaic virus (BaMV) infection on Nicotiana benthamiana plants. One of the upregulated genes was cloned and predicted to contain a TBC domain designated as NbRabGAP1 (Rab GTPase activation protein 1). No significant difference was observed in BaMV accumulation in the NbRabGAP1-knockdown and the control protoplasts. However, BaMV accumulation was 50% and 2% in the inoculated and systemic leaves, respectively, of the knockdown plants to those of the control plants. By measuring the spreading area of BaMV infection foci in the inoculated leaves, we found that BaMV moved less efficiently in the NbRabGAP1-knockdown plants than in the control plants. Transient expression of the wild type NbRabGAP1 significantly increases BaMV accumulation in N. benthamiana. These results suggest that NbRabGAP1 with a functional Rab-GAP activity is involved in virus movement.
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Affiliation(s)
- Ying-Ping Huang
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 402, Taiwan
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Park MR, Seo JK, Kim KH. Viral and nonviral elements in potexvirus replication and movement and in antiviral responses. Adv Virus Res 2013; 87:75-112. [PMID: 23809921 DOI: 10.1016/b978-0-12-407698-3.00003-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In Potato virus X, a member of the genus Potexvirus, special sequences and structures at the 5' and 3' ends of the nontranslated region function as cis-acting elements for viral replication. These elements greatly affect interactions between viral RNAs and those between viral RNAs and host factors. The potexvirus genome encodes five open-reading frames. Viral replicase, which is required for the synthesis of viral RNA, binds viral RNA elements and host factors to form a viral replication complex at the host cellular membrane. The coat protein (CP) and three viral movement proteins (TGB1, TGB2, and TGB3) have critical roles in mediating cell-to-cell viral movement through plasmodesmata by virion formation or by nonvirion ribonucleoprotein (RNP) complex formation with viral movement proteins (TGBs). The RNP complex, like TGB1-CP-viral RNA, is associated with viral replicase and used for immediate reinitiation of viral replication in newly invaded cells. Higher plants have defense mechanisms against potexviruses such as Rx-mediated resistance and RNA silencing. The CP acts as an avirulence effector for plant defense mechanisms, while TGB1 functions as a viral suppressor of RNA silencing, which is the mechanism of innate immune resistance. Here, we describe recent findings concerning the involvement of viral and host factors in potexvirus replication and in antiviral responses to potexvirus infection.
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Affiliation(s)
- Mi-Ri Park
- Department of Agricultural Biotechnology, Plant Genomics and Breeding Institute, Seoul National University, Seoul, Republic of Korea
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28
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Lin KY, Hsu YH, Chen HC, Lin NS. Transgenic resistance to Bamboo mosaic virus by expression of interfering satellite RNA. MOLECULAR PLANT PATHOLOGY 2013; 14:693-707. [PMID: 23675895 PMCID: PMC6638707 DOI: 10.1111/mpp.12040] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Plant genetic engineering has broadened the options for plant virus resistance and is mostly based on pathogen-derived resistance. Previously, we have shown that interfering satellite RNA (satRNA) of Bamboo mosaic virus (satBaMV) greatly reduces Bamboo mosaic virus (BaMV) accumulation and BaMV-induced symptoms in co-inoculated plants. Here, we generated a nonviral source of virus-resistant transgenic Nicotiana benthamiana and Arabidopsis thaliana by introducing interfering satBaMV. Asymptomatic transgenic N. benthamiana lines were highly resistant to BaMV virion and viral RNA infection, and the expression of the transgene BSL6 was higher in asymptomatic than mildly symptomatic lines. In addition, BaMV- and satBaMV-specific small RNAs were detectable only after BaMV challenge, and their levels were associated with genomic viral RNA or satRNA levels. By transcriptomic analysis, the salicylic acid (SA) signalling pathway was not induced in satBaMV transgenic A. thaliana in mock conditions, suggesting that two major antiviral mechanisms, RNA silencing and SA-mediated resistance, are not involved directly in transgenic satBaMV-mediated BaMV interference. In contrast, resistance is associated with the level of the interfering satBaMV transgene. We propose satBaMV-mediated BaMV interference in transgenic plants by competition for replicase with BaMV.
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Affiliation(s)
- Kuan-Yu Lin
- Institute of Biotechnology, National Cheng Kung University, Tainan, 701, Taiwan
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Chen IH, Chiu MH, Cheng SF, Hsu YH, Tsai CH. The glutathione transferase of Nicotiana benthamiana NbGSTU4 plays a role in regulating the early replication of Bamboo mosaic virus. THE NEW PHYTOLOGIST 2013; 199:749-57. [PMID: 23701112 PMCID: PMC3744755 DOI: 10.1111/nph.12304] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 03/28/2013] [Indexed: 05/23/2023]
Abstract
Bamboo mosaic virus (BaMV) is a single-stranded positive-sense RNA virus. One of the plant glutathione S-transferase (GST) genes, NbGSTU4, responds as an upregulated gene in Nicotiana benthamiana post BaMV infection. In order to identify the role of NbGSTU4 in BaMV infection, the expression of NbGSTU4 was knocked down using a virus-induced gene silencing technique or was transiently expressed in N. benthamiana in BaMV inoculation. The results show a significant decrease in BaMV RNA accumulation when the expression level of NbGSTU4 is reduced; whereas the viral RNA accumulation increases when NbGSTU4 is transiently expressed. Furthermore, this study identified that the involvement of NbGSTU4 in viral RNA accumulation occurs by its participation in the viral early replication step. The findings show that the NbGSTU4 protein expressed from Escherichia coli can interact with the 3' untranslated region (UTR) of the BaMV RNA in vitro in the presence of glutathione (GSH). The addition of GSH in the in vitro replication assay shows an enhancement of minus-strand but not plus-strand RNA synthesis. The results suggest that the plant GST protein plays a role in binding viral RNA and delivering GSH to the replication complex to create a reduced condition for BaMV minus-strand RNA synthesis.
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Affiliation(s)
- I-Hsuan Chen
- Graduate Institute of Biotechnology, National Chung Hsing UniversityTaichung, 402, Taiwan
| | - Meng-Hsuen Chiu
- Graduate Institute of Biotechnology, National Chung Hsing UniversityTaichung, 402, Taiwan
| | - Shun-Fang Cheng
- Graduate Institute of Biotechnology, National Chung Hsing UniversityTaichung, 402, Taiwan
| | - Yau-Heiu Hsu
- Graduate Institute of Biotechnology, National Chung Hsing UniversityTaichung, 402, Taiwan
- Graduate Institute of Medical Laboratory Science and Biotechnology, China Medical UniversityTaichung, 404, Taiwan
| | - Ching-Hsiu Tsai
- Graduate Institute of Biotechnology, National Chung Hsing UniversityTaichung, 402, Taiwan
- Graduate Institute of Medical Laboratory Science and Biotechnology, China Medical UniversityTaichung, 404, Taiwan
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Chou YL, Hung YJ, Tseng YH, Hsu HT, Yang JY, Wung CH, Lin NS, Meng M, Hsu YH, Chang BY. The stable association of virion with the triple-gene-block protein 3-based complex of Bamboo mosaic virus. PLoS Pathog 2013; 9:e1003405. [PMID: 23754943 PMCID: PMC3675025 DOI: 10.1371/journal.ppat.1003405] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 04/22/2013] [Indexed: 12/03/2022] Open
Abstract
The triple-gene-block protein 3 (TGBp3) of Bamboo mosaic virus (BaMV) is an integral endoplasmic reticulum (ER) membrane protein which is assumed to form a membrane complex to deliver the virus intracellularly. However, the virus entity that is delivered to plasmodesmata (PD) and its association with TGBp3-based complexes are not known. Results from chemical extraction and partial proteolysis of TGBp3 in membrane vesicles revealed that TGBp3 has a right-side-out membrane topology; i.e., TGBp3 has its C-terminal tail exposed to the outer surface of ER. Analyses of the TGBp3-specific immunoprecipitate of Sarkosyl-extracted TGBp3-based complex revealed that TGBp1, TGBp2, TGBp3, capsid protein (CP), replicase and viral RNA are potential constituents of virus movement complex. Substantial co-fractionation of TGBp2, TGBp3 and CP, but not TGBp1, in the early eluted gel filtration fractions in which virions were detected after TGBp3-specific immunoprecipitation suggested that the TGBp2- and TGBp3-based complex is able to stably associate with the virion. This notion was confirmed by immunogold-labeling transmission electron microscopy (TEM) of the purified virions. In addition, mutational and confocal microscopy analyses revealed that TGBp3 plays a key role in virus cell-to-cell movement by enhancing the TGBp2- and TGBp3-dependent PD localization of TGBp1. Taken together, our results suggested that the cell-to-cell movement of potexvirus requires stable association of the virion cargo with the TGBp2- and TGBp3-based membrane complex and recruitment of TGBp1 to the PD by this complex.
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Affiliation(s)
- Yuan-Lin Chou
- Institute of Biochemistry, National Chung-Hsing University, Taichung, Taiwan, Republic of China
| | - Yi-Jing Hung
- Institute of Biochemistry, National Chung-Hsing University, Taichung, Taiwan, Republic of China
| | - Yang-Hao Tseng
- Institute of Biochemistry, National Chung-Hsing University, Taichung, Taiwan, Republic of China
| | - Hsiu-Ting Hsu
- Institute of Biochemistry, National Chung-Hsing University, Taichung, Taiwan, Republic of China
| | - Jun-Yi Yang
- Institute of Biochemistry, National Chung-Hsing University, Taichung, Taiwan, Republic of China
| | - Chiung-Hua Wung
- Biotechnology Center, National Chung-Hsing University, Taichung, Taiwan, Republic of China
| | - Na-Sheng Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, Republic of China
| | - Menghsiao Meng
- Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung, Taiwan, Republic of China
| | - Yau-Heiu Hsu
- Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung, Taiwan, Republic of China
| | - Ban-Yang Chang
- Institute of Biochemistry, National Chung-Hsing University, Taichung, Taiwan, Republic of China
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Jang C, Seo EY, Nam J, Bae H, Gim YG, Kim HG, Cho IS, Lee ZW, Bauchan GR, Hammond J, Lim HS. Insights into Alternanthera mosaic virus TGB3 Functions: Interactions with Nicotiana benthamiana PsbO Correlate with Chloroplast Vesiculation and Veinal Necrosis Caused by TGB3 Over-Expression. FRONTIERS IN PLANT SCIENCE 2013; 4:5. [PMID: 23386854 PMCID: PMC3560364 DOI: 10.3389/fpls.2013.00005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Accepted: 01/08/2013] [Indexed: 05/18/2023]
Abstract
Alternanthera mosaic virus (AltMV) triple gene block 3 (TGB3) protein is involved in viral movement. AltMV TGB3 subcellular localization was previously shown to be distinct from that of Potato virus X (PVX) TGB3, and a chloroplast binding domain identified; veinal necrosis and chloroplast vesiculation were observed in Nicotiana benthamiana when AltMV TGB3 was over-expressed from PVX. Plants with over-expressed TGB3 showed more lethal damage under dark conditions than under light. Yeast-two-hybrid analysis and bimolecular fluorescence complementation (BiFC) reveal that Arabidopsis thaliana PsbO1 has strong interactions with TGB3; N. benthamiana PsbO (NbPsbO) also showed obvious interaction signals with TGB3 through BiFC. These results demonstrate an important role for TGB3 in virus cell-to-cell movement and virus-host plant interactions. The Photosystem II oxygen-evolving complex protein PsbO interaction with TGB3 is presumed to have a crucial role in symptom development and lethal damage under dark conditions. In order to further examine interactions between AtPsbO1, NbPsbO, and TGB3, and to identify the binding domain(s) in TGB3 protein, BiFC assays were performed between AtPsbO1 or NbPsbO and various mutants of TGB3. Interactions with C-terminally deleted TGB3 were significantly weaker than those with wild-type TGB3, and both N-terminally deleted TGB3 and a TGB3 mutant previously shown to lose chloroplast interactions failed to interact detectably with PsbO in BiFC. To gain additional information about TGB3 interactions in AltMV-susceptible plants, we cloned 12 natural AltMV TGB3 sequence variants into a PVX expression vector to examine differences in symptom development in N. benthamiana. Symptom differences were observed on PVX over-expression, with all AltMV TGB3 variants showing more severe symptoms than the WT PVX control, but without obvious correlation to sequence differences.
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Affiliation(s)
- Chanyong Jang
- Department of Applied Biology, Chungnam National UniversityDaejeon, South Korea
| | - Eun-Young Seo
- Department of Applied Biology, Chungnam National UniversityDaejeon, South Korea
| | - Jiryun Nam
- Department of Applied Biology, Chungnam National UniversityDaejeon, South Korea
| | - Hanhong Bae
- School of Biotechnology, Yeungnam UniversityGyeongsan, South Korea
| | - Yeong Guk Gim
- Department of Applied Biology, Chungnam National UniversityDaejeon, South Korea
| | - Hong Gi Kim
- Department of Applied Biology, Chungnam National UniversityDaejeon, South Korea
| | - In Sook Cho
- National Institute of Horticultural and Herbal Science, Rural Development AdministrationSuwon, South Korea
| | - Zee-Won Lee
- Division of Life Science, Korea Basic Science InstituteDaejeon, South Korea
| | - Gary R. Bauchan
- Electron and Confocal Microscopy Unit, Beltsville Agricultural Research Center, Agricultural Research Service, United States Department of AgricultureBeltsville, MD, USA
| | - John Hammond
- Floral and Nursery Plants Research Unit, US National Arboretum, Agricultural Research Service, United States Department of AgricultureBeltsville, MD, USA
- *Correspondence: John Hammond, Floral and Nursery Plants Research Unit, US National Arboretum, United States Department of Agriculture, Agricultural Research Service, 10300 Baltimore Avenue, B-010A, Beltsville, MD 20705, USA. e-mail: ; Hyoun-Sub Lim, Department of Applied Biology, Chungnam National University, 79 Daehangno, Yuseong-gu, Daejeon 305-764, South Korea. e-mail:
| | - Hyoun-Sub Lim
- Department of Applied Biology, Chungnam National UniversityDaejeon, South Korea
- *Correspondence: John Hammond, Floral and Nursery Plants Research Unit, US National Arboretum, United States Department of Agriculture, Agricultural Research Service, 10300 Baltimore Avenue, B-010A, Beltsville, MD 20705, USA. e-mail: ; Hyoun-Sub Lim, Department of Applied Biology, Chungnam National University, 79 Daehangno, Yuseong-gu, Daejeon 305-764, South Korea. e-mail:
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Sun X, Zhang C. A conserved C-terminal motif is essential for self-interaction of Barley stripe mosaic virus China strain TGB3 protein. Biochem Biophys Res Commun 2012; 426:153-7. [PMID: 22925891 DOI: 10.1016/j.bbrc.2012.08.056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 08/11/2012] [Indexed: 10/28/2022]
Abstract
The triple gene block (TGB) 3 protein is essential for the cell-to-cell movement of Barley stripe mosaic virus (BSMV). Previous studies have shown that TGB3, together with TGB2, facilitates the movement of TGB1 to the plasma membrane. However, the interactions among the three proteins (i.e., TGB3, TGB1, and TGB2) have not been thoroughly understood. The interactions of BSMV China strain (BSMV-CH) TGB3 with itself and with other two TGB proteins were investigated using a Gal4-based yeast two-hybrid system and pull-down assays. The results show that neither TGB1 nor TGB2 interacts with TGB3. However, self-interaction was detected for TGB3. The C-terminal 37 amino acids (amino acids 87-123) containing a conserved C-terminal motif were found required for the self-interaction of TGB3. The roles of the novel property of BSMV-CH TGB3 in virus cell-to-cell movement were discussed.
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Affiliation(s)
- Xianchao Sun
- Chongqing Key Laboratory of Plant Disease Biology, College of Plant Protection, Southwest University, Chongqing 400715, China.
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Chen HC, Kong LR, Yeh TY, Cheng CP, Hsu YH, Lin NS. The conserved 5' apical hairpin stem loops of bamboo mosaic virus and its satellite RNA contribute to replication competence. Nucleic Acids Res 2012; 40:4641-52. [PMID: 22278884 PMCID: PMC3378871 DOI: 10.1093/nar/gks030] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2011] [Revised: 12/30/2011] [Accepted: 01/05/2012] [Indexed: 11/29/2022] Open
Abstract
Satellite RNAs associated with Bamboo mosaic virus (satBaMVs) depend on BaMV for replication and encapsidation. Certain satBaMVs isolated from natural fields significantly interfere with BaMV replication. The 5' apical hairpin stem loop (AHSL) of satBaMV is the major determinant in interference with BaMV replication. In this study, by in vivo competition assay, we revealed that the sequence and structure of AHSL, along with specific nucleotides (C(60) and C(83)) required for interference with BaMV replication, are also involved in replication competition among satBaMV variants. Moreover, all of the 5' ends of natural BaMV isolates contain the similar AHSLs having conserved nucleotides (C(64) and C(86)) with those of interfering satBaMVs, suggesting their co-evolution. Mutational analyses revealed that C(86) was essential for BaMV replication, and that replacement of C(64) with U reduced replication efficiency. The non-interfering satBaMV interfered with BaMV replication with the BaMV-C64U mutant as helper. These findings suggest that two cytosines at the equivalent positions in the AHSLs of BaMV and satBaMV play a crucial role in replication competence. The downregulation level, which is dependent upon the molar ratio of interfering satBaMV to BaMV, implies that there is competition for limited replication machinery.
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Affiliation(s)
- Hsin-Chuan Chen
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei and Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Lih-Ren Kong
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei and Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Ting-Yu Yeh
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei and Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Chi-Ping Cheng
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei and Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Yau-Heiu Hsu
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei and Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Na-Sheng Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei and Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
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34
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Vijayapalani P, Chen JCF, Liou MR, Chen HC, Hsu YH, Lin NS. Phosphorylation of bamboo mosaic virus satellite RNA (satBaMV)-encoded protein P20 downregulates the formation of satBaMV-P20 ribonucleoprotein complex. Nucleic Acids Res 2012; 40:638-49. [PMID: 21965537 PMCID: PMC3258126 DOI: 10.1093/nar/gkr705] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Revised: 08/14/2011] [Accepted: 08/15/2011] [Indexed: 01/13/2023] Open
Abstract
Bamboo mosaic virus (BaMV) satellite RNA (satBaMV) depends on BaMV for its replication and encapsidation. SatBaMV-encoded P20 protein is an RNA-binding protein that facilitates satBaMV systemic movement in co-infected plants. Here, we examined phosphorylation of P20 and its regulatory functions. Recombinant P20 (rP20) was phosphorylated by host cellular kinase(s) in vitro, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and mutational analyses revealed Ser-11 as the phosphorylation site. The phosphor-mimic rP20 protein interactions with satBaMV-translated mutant P20 were affected. In overlay assay, the Asp mutation at S11 (S11D) completely abolished the self-interaction of rP20 and significantly inhibited the interaction with both the WT and S11A rP20. In chemical cross-linking assays, S11D failed to oligomerize. Electrophoretic mobility shift assay and subsequent Hill transformation analysis revealed a low affinity of the phospho-mimicking rP20 for satBaMV RNA. Substantial modulation of satBaMV RNA conformation upon interaction with nonphospho-mimic rP20 in circular dichroism analysis indicated formation of stable satBaMV ribonucleoprotein complexes. The dissimilar satBaMV translation regulation of the nonphospho- and phospho-mimic rP20 suggests that phosphorylation of P20 in the ribonucleoprotein complex converts the translation-incompetent satBaMV RNA to messenger RNA. The phospho-deficient or phospho-mimicking P20 mutant of satBaMV delayed the systemic spread of satBaMV in co-infected Nicotiana benthamiana with BaMV. Thus, satBaMV likely regulates the formation of satBaMV RNP complex during co-infection in planta.
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Affiliation(s)
- Paramasivan Vijayapalani
- The Institute of Plant and Microbial Biology, Academia Sinica, Taipei 115, Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 402, Taiwan, Republic of China
| | - Jeff Chien-Fu Chen
- The Institute of Plant and Microbial Biology, Academia Sinica, Taipei 115, Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 402, Taiwan, Republic of China
| | - Ming-Ru Liou
- The Institute of Plant and Microbial Biology, Academia Sinica, Taipei 115, Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 402, Taiwan, Republic of China
| | - Hsin-Chuan Chen
- The Institute of Plant and Microbial Biology, Academia Sinica, Taipei 115, Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 402, Taiwan, Republic of China
| | - Yau-Heiu Hsu
- The Institute of Plant and Microbial Biology, Academia Sinica, Taipei 115, Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 402, Taiwan, Republic of China
| | - Na-Sheng Lin
- The Institute of Plant and Microbial Biology, Academia Sinica, Taipei 115, Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 402, Taiwan, Republic of China
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Sabanadzovic S, Abou Ghanem-Sabanadzovic N, Tzanetakis IE. Blackberry virus E: an unusual flexivirus. Arch Virol 2011; 156:1665-9. [DOI: 10.1007/s00705-011-1015-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Accepted: 04/30/2011] [Indexed: 11/28/2022]
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36
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One-step reverse transcription loop-mediated isothermal amplification assay for rapid detection of Cymbidium mosaic virus. J Virol Methods 2011; 173:43-8. [PMID: 21237208 DOI: 10.1016/j.jviromet.2011.01.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Revised: 01/05/2011] [Accepted: 01/06/2011] [Indexed: 11/22/2022]
Abstract
Cymbidium mosaic virus (CymMV) is the most prevalent orchid virus. A single-tube one-step betaine-free reverse transcription (RT) loop-mediated isothermal amplification (LAMP) assay was developed for the rapid and easy detection of orchid-infecting CymMV. Five sets of primers were designed based on the conserved regions among various virus isolates. The specificity and the sensitivity of the assay were then evaluated using the RT-LAMP reaction. Within 1h under isothermal conditions at 60°C the target viral gene was amplified successfully. This RT-LAMP assay was found to be quick, specific, sensitive and easy to perform assay that involved only one step and was simpler to carry out than alternative approaches. Thus this assay is an alternative for the rapid and easy detection of CymMV in orchids. This is first time that a RT-LAMP method for the detection of an orchid virus has been described.
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Cheng SF, Huang YP, Wu ZR, Hu CC, Hsu YH, Tsai CH. Identification of differentially expressed genes induced by Bamboo mosaic virus infection in Nicotiana benthamiana by cDNA-amplified fragment length polymorphism. BMC PLANT BIOLOGY 2010; 10:286. [PMID: 21184690 PMCID: PMC3024324 DOI: 10.1186/1471-2229-10-286] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Accepted: 12/27/2010] [Indexed: 05/03/2023]
Abstract
BACKGROUND The genes of plants can be up- or down-regulated during viral infection to influence the replication of viruses. Identification of these differentially expressed genes could shed light on the defense systems employed by plants and the mechanisms involved in the adaption of viruses to plant cells. Differential gene expression in Nicotiana benthamiana plants in response to infection with Bamboo mosaic virus (BaMV) was revealed using cDNA-amplified fragment length polymorphism (AFLP). RESULTS Following inoculation with BaMV, N. benthamiana displayed differential gene expression in response to the infection. Isolation, cloning, and sequencing analysis using cDNA-AFLP furnished 90 cDNA fragments with eight pairs of selective primers. Fifteen randomly selected genes were used for a combined virus-induced gene silencing (VIGS) knockdown experiment, using BaMV infection to investigate the roles played by these genes during viral infection, specifically addressing the means by which these genes influence the accumulation of BaMV protein. Nine of the 15 genes showed either a positive or a negative influence on the accumulation of BaMV protein. Six knockdown plants showed an increase in the accumulation of BaMV, suggesting that they played a role in the resistance to viral infection, while three plants showed a reduction in coat protein, indicating a positive influence on the accumulation of BaMV in plants. An interesting observation was that eight of the nine plants showing an increase in BaMV coat protein were associated with cell rescue, defense, death, aging, signal transduction, and energy production. CONCLUSIONS This study reports an efficient and straightforward method for the identification of host genes involved in viral infection. We succeeded in establishing a cDNA-AFLP system to help track changes in gene expression patterns in N. benthamiana plants when infected with BaMV. The combination of both DNA-AFLP and VIGS methodologies made it possible to screen a large number of genes and identify those associated with infections of plant viruses. In this report, 9 of the 15 analyzed genes exhibited either a positive or a negative influence on the accumulation of BaMV in N. benthamiana plants.
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Affiliation(s)
- Shun-Fang Cheng
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Ying-Ping Huang
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Zi-Rong Wu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Chung-Chi Hu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Yau-Heiu Hsu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 40227, Taiwan
- Graduate Institute of Medical Laboratory Science and Biotechnology, China Medical University, Taichung, 404, Taiwan
| | - Ching-Hsiu Tsai
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 40227, Taiwan
- Graduate Institute of Medical Laboratory Science and Biotechnology, China Medical University, Taichung, 404, Taiwan
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Lim HS, Vaira AM, Bae H, Bragg JN, Ruzin SE, Bauchan GR, Dienelt MM, Owens RA, Hammond J. Mutation of a chloroplast-targeting signal in Alternanthera mosaic virus TGB3 impairs cell-to-cell movement and eliminates long-distance virus movement. J Gen Virol 2010; 91:2102-2115. [PMID: 20392901 DOI: 10.1099/vir.0.019448-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Cell-to-cell movement of potexviruses requires coordinated action of the coat protein and triple gene block (TGB) proteins. The structural properties of Alternanthera mosaic virus (AltMV) TGB3 were examined by methods differentiating between signal peptides and transmembrane domains, and its subcellular localization was studied by Agrobacterium-mediated transient expression and confocal microscopy. Unlike potato virus X (PVX) TGB3, AltMV TGB3 was not associated with the endoplasmic reticulum, and accumulated preferentially in mesophyll cells. Deletion and site-specific mutagenesis revealed an internal signal VL(17,18) of TGB3 essential for chloroplast localization, and either deletion of the TGB3 start codon or alteration of the chloroplast-localization signal limited cell-to-cell movement to the epidermis, yielding a virus that was unable to move into the mesophyll layer. Overexpression of AltMV TGB3 from either AltMV or PVX infectious clones resulted in veinal necrosis and vesiculation at the chloroplast membrane, a cytopathology not observed in wild-type infections. The distinctive mesophyll and chloroplast localization of AltMV TGB3 highlights the critical role played by mesophyll targeting in virus long-distance movement within plants.
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Affiliation(s)
- Hyoun-Sub Lim
- USDA-ARS, Plant Sciences Institute, Molecular Plant Pathology Laboratory, B-004, 10300 Baltimore Avenue, Beltsville, MD 20705, USA
| | - Anna Maria Vaira
- CNR, Istituto di Virologia Vegetale, Strada delle Cacce 73, Torino 10135, Italy
- USDA-ARS, Plant Sciences Institute, Molecular Plant Pathology Laboratory, B-004, 10300 Baltimore Avenue, Beltsville, MD 20705, USA
| | - Hanhong Bae
- School of Biotechnology, Yeungnam University, Geongsan 712-749, Republic of Korea
| | - Jennifer N Bragg
- USDA-ARS, Western Regional Research Center, 800 Buchanan Street, Albany, CA 94710, USA
| | - Steven E Ruzin
- University of California-Berkeley, CNR, 381 Koshland Hall, Berkeley, CA 94720, USA
| | - Gary R Bauchan
- USDA-ARS, Plant Sciences Institute, Electron and Confocal Microscopy Unit, B-465, 10300 Baltimore Avenue, Beltsville, MD 20705, USA
| | - Margaret M Dienelt
- USDA-ARS, Plant Sciences Institute, Molecular Plant Pathology Laboratory, B-004, 10300 Baltimore Avenue, Beltsville, MD 20705, USA
| | - Robert A Owens
- USDA-ARS, Plant Sciences Institute, Molecular Plant Pathology Laboratory, B-004, 10300 Baltimore Avenue, Beltsville, MD 20705, USA
| | - John Hammond
- USDA-ARS, Plant Sciences Institute, Molecular Plant Pathology Laboratory, B-004, 10300 Baltimore Avenue, Beltsville, MD 20705, USA
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Satellite RNAs and Satellite Viruses of Plants. Viruses 2009; 1:1325-50. [PMID: 21994595 PMCID: PMC3185516 DOI: 10.3390/v1031325] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Revised: 12/07/2009] [Accepted: 12/07/2009] [Indexed: 12/24/2022] Open
Abstract
The view that satellite RNAs (satRNAs) and satellite viruses are purely molecular parasites of their cognate helper viruses has changed. The molecular mechanisms underlying the synergistic and/or antagonistic interactions among satRNAs/satellite viruses, helper viruses, and host plants are beginning to be comprehended. This review aims to summarize the recent achievements in basic and practical research, with special emphasis on the involvement of RNA silencing mechanisms in the pathogenicity, population dynamics, and, possibly, the origin(s) of these subviral agents. With further research following current trends, the comprehensive understanding of satRNAs and satellite viruses could lead to new insights into the trilateral interactions among host plants, viruses, and satellites.
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40
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Lu HC, Chen CE, Tsai MH, Wang HI, Su HJ, Yeh HH. Cymbidium mosaic potexvirus isolate-dependent host movement systems reveal two movement control determinants and the coat protein is the dominant. Virology 2009; 388:147-59. [PMID: 19345971 PMCID: PMC7103407 DOI: 10.1016/j.virol.2009.02.049] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Revised: 01/28/2009] [Accepted: 02/28/2009] [Indexed: 11/30/2022]
Abstract
Little is known about how plant viruses of a single species exhibit different movement behavior in different host species. Two Cymbidium mosaic potexvirus (CymMV) isolates, M1 and M2, were studied. Both can infect Phalaenopsis orchids, but only M1 can systemically infect Nicotiana benthamiana plants. Protoplast inoculation and whole-mount in situ hybridization revealed that both isolates can replicate in N. benthamiana; however, M2 was restricted to the initially infected cells. Genome shuffling between M1 and M2 revealed that two control modes are involved in CymMV host dependent movement. The M1 coat protein (CP) plays a dominant role in controlling CymMV movement between cells, because all chimeric CymMV viruses containing the M1 CP systemically infected N. benthamiana plants. Without the M1 CP, one chimeric virus containing the combination of the M1 triple gene block proteins (TGBps), the M2 5' RNA (1-4333), and the M2 CP effectively moved in N. benthamiana plants. Further complementation analysis revealed that M1 TGBp1 and TGBp3 are co-required to complement the movement of the chimeric viruses in N. benthamiana. The amino acids within the CP, TGBp1 and TGBp3 which are required or important for CymMV M2 movement in N. benthamiana plants were mapped. The required amino acids within the CP map to the predicted RNA binding domain. RNA-protein binding assays revealed that M1 CP has higher RNA binding affinity than does M2 CP. Yeast two-hybrid assays to detect all possible interactions of M1 TGBps and CP, and only TGBp1 and CP self-interactions were observed.
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Affiliation(s)
- Hsiang-Chia Lu
- Department of Plant Pathology and Microbiology, National Taiwan University, 1, sec 4, Roosevelt Road, Taipei 106, Taiwan
| | - Cheng-En Chen
- Department of Plant Pathology and Microbiology, National Taiwan University, 1, sec 4, Roosevelt Road, Taipei 106, Taiwan
| | - Meng-Hsiun Tsai
- Department of Management Information Systems, National Chung Hsing University, 250, Kuo Kuang Rd., Taichung 402, Taiwan
| | - Hsiang-iu Wang
- Department of Computer Science, National Tsing Hua University, 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan
| | - Hong-Ji Su
- Department of Plant Pathology and Microbiology, National Taiwan University, 1, sec 4, Roosevelt Road, Taipei 106, Taiwan
| | - Hsin-Hung Yeh
- Department of Plant Pathology and Microbiology, National Taiwan University, 1, sec 4, Roosevelt Road, Taipei 106, Taiwan
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Palani PV, Chiu M, Chen W, Wang CC, Lin CC, Hsu CC, Cheng CP, Chen CM, Hsu YH, Lin NS. Subcellular localization and expression of bamboo mosaic virus satellite RNA-encoded protein. J Gen Virol 2009; 90:507-518. [PMID: 19141462 PMCID: PMC2885055 DOI: 10.1099/vir.0.004994-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The satellite RNA of bamboo mosaic virus (satBaMV) has a single open reading frame encoding a non-structural protein, P20, which facilitates long-distance movement of satBaMV in BaMV and satBaMV co-infected plants. Immunohistochemistry and immunoelectron microscopy revealed that the P20 protein accumulated in the cytoplasm and nuclei in co-infected cells. P20 and the helper virus coat protein (CP) were highly similar in their subcellular localization, except that aggregates of BaMV virions were not labelled with anti-P20 serum. The BaMV CP protein was fairly abundant in mesophyll cells, whilst P20 was more frequently detected in mesophyll cells and vascular tissues. The expression kinetics of the P20 protein was similar to but slightly earlier than that of CP in co-infected Bambusa oldhamii protoplasts and Nicotiana benthamiana leaves. However, satBaMV-encoded protein levels declined rapidly in the late phase of co-infection. During co-infection, in addition to the intact P20, a low-molecular-mass polypeptide of 16 kDa was identified as a P20 C-terminally truncated product; the possible method of generation of the truncated protein is discussed.
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Affiliation(s)
| | - Morgan Chiu
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan 115, ROC
| | - Wei Chen
- Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung, Taiwan 402, ROC
| | - Ching-Chi Wang
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan 115, ROC
| | - Choy-Chieng Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan 115, ROC
| | - Chuen-Chi Hsu
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan 115, ROC
| | - Chi-Ping Cheng
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan 115, ROC
| | - Chung-Mong Chen
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan 115, ROC
| | - Yau-Heiu Hsu
- Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung, Taiwan 402, ROC
| | - Na-Sheng Lin
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan 115, ROC.,Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung, Taiwan 402, ROC.,Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan 115, ROC
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Huang YW, Hu CC, Lin NS, Tsai CH, Hsu YH. In vitro replication of Bamboo mosaic virus satellite RNA. Virus Res 2008; 136:98-106. [PMID: 18538884 DOI: 10.1016/j.virusres.2008.04.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Revised: 04/13/2008] [Accepted: 04/28/2008] [Indexed: 01/17/2023]
Abstract
An in vitro system was applied to analyze the replication of a satellite RNA of Bamboo mosaic virus (BaMV), designated satBaMV RNA, using solubilized membrane-bound RNA-dependent RNA polymerase (RdRp) complexes isolated from BaMV-infected Nicotiana benthamiana. After removal of endogenous templates, the RdRp complexes of BaMV catalyzed RNA synthesis upon the addition of the full-length positive (+)- or negative (-)-strand satBaMV RNA transcripts used as templates. Both (+)- and (-)-satBaMV RNA products were detected when only the (+)-satBaMV RNA was used as a template in the in vitro RdRp assays, which further demonstrated the capability of the RdRp preparation to complete the replication cycles of satBaMV RNAs. In addition, use of 5' rapid amplification of cDNA ends and DNA sequencing showed that the BaMV RdRp preparation could specifically recognize the promoter sequences in the (-)-satBaMV RNA for accurate initiation of (+)-satBaMV RNA synthesis. The results suggested that the same enzyme complexes could be used for the replication of both BaMV genomic and satBaMV RNAs. The soluble and template-dependent RdRp could be further used in mechanistic studies, such as those analyzing the cis-elements and candidate host factors required for satBaMV RNA replication in vitro.
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Affiliation(s)
- Ying-Wen Huang
- Graduate Institute of Biotechnology, National Chung Hsing University, 250 Kuokuang Road, Taichung 40227, Taiwan, ROC
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Revised sequence of foxtail mosaic virus reveals a triple gene block structure similar to potato virus X. Arch Virol 2007; 153:223-6. [PMID: 17955161 DOI: 10.1007/s00705-007-1057-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Accepted: 08/09/2007] [Indexed: 10/22/2022]
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