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Carr JP. Engineered Resistance to Tobamoviruses. Viruses 2024; 16:1007. [PMID: 39066170 PMCID: PMC11281658 DOI: 10.3390/v16071007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2024] [Revised: 06/17/2024] [Accepted: 06/19/2024] [Indexed: 07/28/2024] Open
Abstract
Tobacco mosaic virus (TMV) was the first virus to be studied in detail and, for many years, TMV and other tobamoviruses, particularly tomato mosaic virus (ToMV) and tobamoviruses infecting pepper (Capsicum spp.), were serious crop pathogens. By the end of the twentieth and for the first decade of the twenty-first century, tobamoviruses were under some degree of control due to introgression of resistance genes into commercial tomato and pepper lines. However, tobamoviruses remained important models for molecular biology, biotechnology and bio-nanotechnology. Recently, tobamoviruses have again become serious crop pathogens due to the advent of tomato brown rugose fruit virus, which overcomes tomato resistance against TMV and ToMV, and the slow but apparently inexorable worldwide spread of cucumber green mottle mosaic virus, which threatens all cucurbit crops. This review discusses a range of mainly molecular biology-based approaches for protecting crops against tobamoviruses. These include cross-protection (using mild tobamovirus strains to 'immunize' plants against severe strains), expressing viral gene products in transgenic plants to inhibit the viral infection cycle, inducing RNA silencing against tobamoviruses by expressing virus-derived RNA sequences in planta or by direct application of double-stranded RNA molecules to non-engineered plants, gene editing of host susceptibility factors, and the transfer and optimization of natural resistance genes.
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Affiliation(s)
- John Peter Carr
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
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2
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Ibrahim A, Yang X, Liu C, Cooper KD, Bishop BA, Zhu M, Kwon S, Schoelz JE, Nelson RS. Plant SNAREs SYP22 and SYP23 interact with Tobacco mosaic virus 126 kDa protein and SYP2s are required for normal local virus accumulation and spread. Virology 2020; 547:57-71. [PMID: 32560905 DOI: 10.1016/j.virol.2020.04.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 03/18/2020] [Accepted: 04/07/2020] [Indexed: 10/24/2022]
Abstract
Viral proteins often interact with multiple host proteins during virus accumulation and spread. Identities and functions of all interacting host proteins are not known. Through a yeast two-hybrid screen an Arabidopsis thaliana Qa-SNARE protein [syntaxin of plants 23 (AtSYP23)], associated with pre-vacuolar compartment and vacuolar membrane fusion activities, interacted with Tobacco mosaic virus (TMV) 126 kDa protein, associated with virus accumulation and spread. In planta, AtSYP23 and AtSYP22 each fused with mCherry, co-localized with 126 kDa protein-GFP. Additionally, A. thaliana and Nicotiana benthamiana SYP2 proteins and 126 kDa protein interacted during bimolecular fluorescence complementation analysis. Decreased TMV accumulation in Arabidopsis plants lacking SYP23 and in N. benthamiana plants subjected to virus-induced gene silencing (VIGS) of SYP2 orthologs was observed. Diminished TMV accumulation during VIGS correlated with less intercellular virus spread. The inability to eliminate virus accumulation suggests that SYP2 proteins function redundantly for TMV accumulation, as for plant development.
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Affiliation(s)
- Amr Ibrahim
- Noble Research Institute, LLC, Ardmore, OK, 73401, USA; Department of Nucleic Acid and Protein Structure, Agricultural Genetic Engineering Research Institute, Agricultural Research Center, Giza, Egypt.
| | - Xiaohua Yang
- Noble Research Institute, LLC, Ardmore, OK, 73401, USA
| | - Chengke Liu
- Noble Research Institute, LLC, Ardmore, OK, 73401, USA
| | | | | | - Min Zhu
- Noble Research Institute, LLC, Ardmore, OK, 73401, USA
| | - Soonil Kwon
- Noble Research Institute, LLC, Ardmore, OK, 73401, USA
| | - James E Schoelz
- Division of Plant Sciences, University of Missouri, Columbia, MO, 65211, USA
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Dixit S, Henderson JC, Alfonzo JD. Multi-Substrate Specificity and the Evolutionary Basis for Interdependence in tRNA Editing and Methylation Enzymes. Front Genet 2019; 10:104. [PMID: 30838029 PMCID: PMC6382703 DOI: 10.3389/fgene.2019.00104] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 01/30/2019] [Indexed: 12/12/2022] Open
Abstract
Among tRNA modification enzymes there is a correlation between specificity for multiple tRNA substrates and heteromultimerization. In general, enzymes that modify a conserved residue in different tRNA sequences adopt a heterodimeric structure. Presumably, such changes in the oligomeric state of enzymes, to gain multi-substrate recognition, are driven by the need to accommodate and catalyze a particular reaction in different substrates while maintaining high specificity. This review focuses on two classes of enzymes where the case for multimerization as a way to diversify molecular recognition can be made. We will highlight several new themes with tRNA methyltransferases and will also discuss recent findings with tRNA editing deaminases. These topics will be discussed in the context of several mechanisms by which heterodimerization may have been achieved during evolution and how these mechanisms might impact modifications in different systems.
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Affiliation(s)
| | | | - Juan D. Alfonzo
- Department of Microbiology, The Ohio State Biochemistry Program, The Center for RNA Biology, The Ohio State University, Columbus, OH, United States
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4
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Abstract
Tobacco mosaic virus and other tobamoviruses have served as models for studying the mechanisms of viral RNA replication. In tobamoviruses, genomic RNA replication occurs via several steps: (a) synthesis of viral replication proteins by translation of the genomic RNA; (b) translation-coupled binding of the replication proteins to a 5'-terminal region of the genomic RNA; (c) recruitment of the genomic RNA by replication proteins onto membranes and formation of a complex with host proteins TOM1 and ARL8; (d) synthesis of complementary (negative-strand) RNA in the complex; and (e) synthesis of progeny genomic RNA. This article reviews current knowledge on tobamovirus RNA replication, particularly regarding how the genomic RNA is specifically selected as a replication template and how the replication proteins are activated. We also focus on the roles of the replication proteins in evading or suppressing host defense systems.
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Affiliation(s)
- Kazuhiro Ishibashi
- Plant and Microbial Research Unit, Division of Plant and Microbial Sciences, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization (NARO), Tsukuba 305-8602, Japan ,
| | - Masayuki Ishikawa
- Plant and Microbial Research Unit, Division of Plant and Microbial Sciences, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization (NARO), Tsukuba 305-8602, Japan ,
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Hyodo K, Okuno T. Pathogenesis mediated by proviral host factors involved in translation and replication of plant positive-strand RNA viruses. Curr Opin Virol 2016; 17:11-18. [DOI: 10.1016/j.coviro.2015.11.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 11/05/2015] [Accepted: 11/11/2015] [Indexed: 01/04/2023]
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Saxena P, Lomonossoff GP. Virus infection cycle events coupled to RNA replication. ANNUAL REVIEW OF PHYTOPATHOLOGY 2014; 52:197-212. [PMID: 24906127 DOI: 10.1146/annurev-phyto-102313-050205] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Replication, the process by which the genetic material of a virus is copied to generate multiple progeny genomes, is the central part of the virus infection cycle. For an infection to be productive, it is essential that this process is coordinated with other aspects of the cycle, such as translation of the viral genome, encapsidation, and movement of the genome between cells. In the case of positive-strand RNA viruses, this represents a particular challenge, as the infecting genome must not only be replicated but also serve as an mRNA for the production of the replication-associated proteins. In recent years, it has become apparent that in positive-strand RNA plant viruses all the aspects of the infection cycle are intertwined. This article reviews the current state of knowledge regarding replication-associated events in such viruses.
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Affiliation(s)
- Pooja Saxena
- Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom; ,
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Kang JW, Park YS, Lee DH, Kim MS, Bak Y, Ham SY, Park SH, Kim H, Ahn JH, Hong JT, Yoon DY. Interaction network mapping among IL-32 isoforms. Biochimie 2014; 101:248-51. [PMID: 24472437 DOI: 10.1016/j.biochi.2014.01.013] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 01/17/2014] [Indexed: 01/15/2023]
Abstract
IL-32 has been studied for its pleiotropic effects ranging from host immune responses to cell differentiation. Although several IL-32 isoforms have been characterized for their effects on cells, the roles of the others remain unclear. We previously reported that IL-32δ interacted with IL-32β and inhibited IL-32β-mediated IL-10 production. Thus, we performed comprehensive analyses to reveal more interactions between IL-32 isoforms in this study. We screened the interactions of 81 combinations of nine IL-32 isoforms by using a yeast two-hybrid assay, which identified 13 heterodimeric interactions. We verified these results by using reciprocal immunoprecipitation assays and reconfirmed 10 interactions, and presented the interaction network map between IL-32 isoforms. Our data suggest that IL-32 may have diverse intracellular effects through the interactions with its different isoforms.
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Affiliation(s)
- Jeong-Woo Kang
- Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea
| | - Yun Sun Park
- Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea
| | - Dong Hun Lee
- Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea
| | - Man Sub Kim
- Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea
| | - Yesol Bak
- Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea
| | - Sun Young Ham
- Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea
| | - Su Ho Park
- Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea
| | - Heejong Kim
- Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea
| | - Joong Hoon Ahn
- Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea
| | - Jin Tae Hong
- College of Pharmacy and Medical Research Center, Chungbuk National University, 12 Gashin-dong, Heungduk-gu, Cheongju, Chungbuk 361-463, Republic of Korea
| | - Do-Young Yoon
- Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea.
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Hafrén A, Eskelin K, Mäkinen K. Ribosomal protein P0 promotes Potato virus A infection and functions in viral translation together with VPg and eIF(iso)4E. J Virol 2013; 87:4302-12. [PMID: 23365448 PMCID: PMC3624370 DOI: 10.1128/jvi.03198-12] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Accepted: 01/25/2013] [Indexed: 11/20/2022] Open
Abstract
We report here that the acidic ribosomal protein P0 is a component of the membrane-associated Potato virus A (PVA) ribonucleoprotein complex. As a constituent of the ribosomal stalk, P0 functions in translation. Although the ribosomal stalk proteins P0, P1, P2, and P3 are all important for PVA infection, P0 appears to have a distinct role from those of the other stalk proteins in infection. Our results indicate that P0 also regulates viral RNA functions as an extraribosomal protein. We reported previously that PVA RNA can be targeted by VPg to a specific gene expression pathway that protects the viral RNA from degradation and facilitates its translation. Here, we show that P0 is essential for this activity of VPg, similar to eIF4E/eIF(iso)4E. We also demonstrate that VPg, P0, and eIF(iso)4E synergistically enhance viral translation. Interestingly, the positive effects of VPg and P0 on viral translation were negatively correlated with the cell-to-cell spread of infection, suggesting that these processes may compete for viral RNA.
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Affiliation(s)
- Anders Hafrén
- Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland
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Wang LY, Lin SS, Hung TH, Li TK, Lin NC, Shen TL. Multiple domains of the tobacco mosaic virus p126 protein can independently suppress local and systemic RNA silencing. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2012; 25:648-57. [PMID: 22324815 DOI: 10.1094/mpmi-06-11-0155] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Small RNA-mediated RNA silencing is a widespread antiviral mechanism in plants and other organisms. Many viruses encode suppressors of RNA silencing for counter-defense. The p126 protein encoded by Tobacco mosaic virus (TMV) has been reported to be a suppressor of RNA silencing but the mechanism of its function remains unclear. This protein is unique among the known plant viral silencing suppressors because of its large size and multiple domains. Here, we report that the methyltransferase, helicase, and nonconserved region II (NONII) of p126 each has silencing-suppressor function. The silencing-suppression activities of methyltransferase and helicase can be uncoupled from their enzyme activities. Specific amino acids in NONII previously shown to be crucial for viral accumulation and symptom development are also crucial for silencing suppression. These results suggest that some viral proteins have evolved to possess modular structural domains that can independently interfere with host silencing, and that this may be an effective mechanism of increasing the robustness of a virus.
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Affiliation(s)
- Li-Ya Wang
- Department of Plant Pathology and Microbiology, College of Bioresources and Agriculture, National Taiwan University, Taipei, Taiwan
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10
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Hu RH, Lin MC, Hsu YH, Meng M. Mutational effects of the consensus aromatic residues in the mRNA capping domain of Bamboo mosaic virus on GTP methylation and virus accumulation. Virology 2011; 411:15-24. [PMID: 21227477 DOI: 10.1016/j.virol.2010.12.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 10/29/2010] [Accepted: 12/14/2010] [Indexed: 10/18/2022]
Abstract
RNA viruses classified in the alphavirus-like superfamily possess a distinct capping domain, catalyzing GTP methylation and subsequent transfer of the m(7)GMP moiety from m(7)GTP to the 5'-diphosphate end of viral RNA. The H68A mutation in the capping domain of Bamboo mosaic virus enhanced GTP methylation but disabled the following transguanylation, making it possible to characterize the enzyme's methyltransferase activity separately. To explore the involvement of aromatic amino acids in substrate recognition, consensus aromatic residues in the viral domain were subjected to mutational analysis in the background of H68A. Several residues, including Y126, F144, F161, Y192, Y203, Y213, and W222, were found to be critical for GTP methylation and S-adenosylmethionine (AdoMet) binding. These mutations, except for Y213, also adversely affected the GTP binding, but less extensively. In general, the mutations decreasing the activity for GTP methylation also had correspondingly detrimental effects on virus accumulation.
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Affiliation(s)
- Rei-Hsing Hu
- Graduate Institute of Biotechnology, National Chung Hsing University, 250 Kuo-Kuang Rd, Taichung, Taiwan 40227, ROC
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Ishibashi K, Nishikiori M, Ishikawa M. Interactions between tobamovirus replication proteins and cellular factors: their impacts on virus multiplication. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:1413-9. [PMID: 20636106 DOI: 10.1094/mpmi-04-10-0102] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Most viral gene products function inside cells in the presence of various host proteins, nucleic acids, and lipids. Thus, viral gene products come into direct contact with these molecules. The replication proteins of tobamovirus participate not only in viral genome replication but also in counterdefense mechanisms against RNA silencing and other plant defense systems. Accumulating evidence indicates that these functions are carried out through interactions with specific host components. Interactions with some cellular factors, however, are inhibitory to virus multiplication and contribute to host range restriction of tobamovirus. The interactions that have positive and negative impacts on virus multiplication should have been maintained and lost, respectively, during adaptation of the viruses to their respective natural hosts. This review lists the host factors that interact with the replication proteins of tobamovirus and discusses how they influence multiplication of the virus.
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Affiliation(s)
- Kazuhiro Ishibashi
- Division of Plant Sciences, National Institute of Agrobiological Sciences, Tsukuba 305-8602, Japan
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Annamalai P, Rofail F, Demason DA, Rao ALN. Replication-coupled packaging mechanism in positive-strand RNA viruses: synchronized coexpression of functional multigenome RNA components of an animal and a plant virus in Nicotiana benthamiana cells by agroinfiltration. J Virol 2008; 82:1484-95. [PMID: 18032497 PMCID: PMC2224467 DOI: 10.1128/jvi.01540-07] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2007] [Accepted: 11/12/2007] [Indexed: 11/20/2022] Open
Abstract
Flock house virus (FHV), a bipartite RNA virus of insects and a member of the Nodaviridae family, shares viral replication features with the tripartite brome mosaic virus (BMV), an RNA virus that infects plants and is a member of the Bromoviridae family. In BMV and FHV, genome packaging is coupled to replication, a widely conserved mechanism among positive-strand RNA viruses of diverse origin. To unravel the events that modulate the mechanism of replication-coupled packaging, in this study, we have extended the transfer DNA (T-DNA)-based agroinfiltration system to express functional genome components of FHV in plant cells (Nicotiana benthamiana). Replication, intracellular membrane localization, and packaging characteristics in agroinfiltrated plant cells revealed that T-DNA plasmids of FHV were biologically active and faithfully mimicked complete replication and packaging behavior similar to that observed for insect cells. Synchronized coexpression of wild-type BMV and FHV genome components in plant cells resulted in the assembly of virions packaging the respective viral progeny RNA. To further elucidate the link between replication and packaging, coat protein (CP) open reading frames were precisely exchanged between BMV RNA 3 (B3) and FHV RNA 2 (F2), creating chimeric RNAs expressing heterologous CP genes (B3/FCP and F2/BCP). Coinfiltration of each chimera with its corresponding genome counterpart to provide viral replicase (B1+B2+B3/FCP and F1+F2/BCP) resulted in the expected progeny profiles, but virions exhibited a nonspecific packaging phenotype. Complementation with homologous replicase (with respect to CP) failed to enhance packaging specificity. Taken together, we propose that the transcription of CP mRNA from homologous replication and its translation must be synchronized to confer packaging specificity.
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Affiliation(s)
- Padmanaban Annamalai
- University of California, Plant Pathology, 3264 Webber Hall, Riverside, CA 92521-0122, USA
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Beauchemin C, Boutet N, Laliberté JF. Visualization of the interaction between the precursors of VPg, the viral protein linked to the genome of turnip mosaic virus, and the translation eukaryotic initiation factor iso 4E in Planta. J Virol 2007; 81:775-82. [PMID: 17079311 PMCID: PMC1797466 DOI: 10.1128/jvi.01277-06] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2006] [Accepted: 10/20/2006] [Indexed: 01/20/2023] Open
Abstract
The RNA genome of Turnip mosaic virus is covalently linked at its 5' end to a viral protein known as VPg. This protein binds to the translation eukaryotic initiation factor iso 4E [eIF(iso)4E]. This interaction has been shown to be important for virus infection, although its exact biological function(s) has not been elucidated. In this study, we investigated the subcellular site of the VPg-eIF(iso)4E interaction using bimolecular fluorescence complementation (BiFC). As a first step, eIF(iso)4E, 6K-VPg-Pro, and VPg-Pro were expressed as full-length green fluorescent protein (GFP) fusions in Nicotiana benthamiana, and their subcellular localizations were visualized by confocal microscopy. eIF(iso)4E was predominantly associated with the endoplasmic reticulum (ER), and VPg-Pro was observed in the nucleus and possibly the nucleolus, while 6K-VPg-Pro-GFP induced the formation of cytoplasmic vesicles budding from the ER. In BiFC experiments, reconstituted green fluorescence was observed throughout the nucleus, with a preferential accumulation in subnuclear structures when the GFP split fragments were fused to VPg-Pro and eIF(iso)4E. On the other hand, the interaction of 6K-VPg-Pro with eIF(iso)4E was observed in cytoplasmic vesicles embedded in the ER. These data suggest that the association of VPg with the translation factor might be needed for two different functions, depending of the VPg precursor involved in the interaction. VPg-Pro interaction with eIF(iso)4E may be involved in perturbing normal cellular functions, while 6K-VPg-Pro interaction with the translation factor may be needed for viral RNA translation and/or replication.
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Affiliation(s)
- Chantal Beauchemin
- Institut Armand-Frappier, Institut National de la Recherche Scientifique, 531 Boulevard des Prairies, Laval, Québec, Canada H7V 1B7
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Mizumoto H, Iwakawa HO, Kaido M, Mise K, Okuno T. Cap-independent translation mechanism of red clover necrotic mosaic virus RNA2 differs from that of RNA1 and is linked to RNA replication. J Virol 2006; 80:3781-91. [PMID: 16571795 PMCID: PMC1440462 DOI: 10.1128/jvi.80.8.3781-3791.2006] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The genome of Red clover necrotic mosaic virus (RCNMV) in the genus Dianthovirus is divided into two RNA molecules of RNA1 and RNA2, which have no cap structure at the 5' end and no poly(A) tail at the 3' end. The 3' untranslated region (3' UTR) of RCNMV RNA1 contains an essential RNA element (3'TE-DR1), which is required for cap-independent translation. In this study, we investigated a cap-independent translational mechanism of RNA2 using a firefly luciferase (Luc) gene expression assay system in cowpea protoplasts and a cell-free lysate (BYL) prepared from evacuolated tobacco BY2 protoplasts. We were unable to detect cis-acting RNA sequences in RNA2 that can replace the function of a cap structure, such as the 3'TE-DR1 of RNA1. However, the uncapped reporter RNA2, RNA2-Luc, in which the Luc open reading frame (ORF) was inserted between the 5' UTR and the movement protein ORF, was effectively translated in the presence of p27 and p88 in protoplasts in which RNA2-Luc was replicated. Time course experiments in protoplasts showed that the translational activity of RNA2-Luc did not reflect the amount of RNA2. Mutations in cis-acting RNA replication elements of RNA2 abolished the cap-independent translational activity of RNA2-Luc, suggesting that the translational activity of RNA2-Luc is coupled to RNA replication. Our results show that the translational mechanism differs between two segmented genomic RNAs of RCNMV. We present a model in which only RNA2 that is generated de novo through the viral RNA replication machinery functions as mRNA for translation.
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Affiliation(s)
- Hiroyuki Mizumoto
- Laboratory of Plant Pathology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kitashirakawa, Kyoto 606-8502, Japan
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Sanfaçon H. Replication of positive-strand RNA viruses in plants: contact points between plant and virus components. ACTA ACUST UNITED AC 2005. [DOI: 10.1139/b05-121] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Positive-strand RNA viruses constitute the largest group of plant viruses and have an important impact on world agriculture. These viruses have small genomes that encode a limited number of proteins and depend on their hosts to complete the various steps of their replication cycle. In this review, the contact points between positive-strand RNA plant viruses and their hosts, which are necessary for the translation and replication of the viral genomes, are discussed. Special emphasis is placed on the description of viral replication complexes that are associated with specific membranous compartments derived from plant intracellular membranes and contain viral RNAs and proteins as well as a variety of host proteins. These complexes are assembled via an intricate network of protein–protein, protein–membrane, and protein–RNA interactions. The role of host factors in regulating the assembly, stability, and activity of viral replication complexes are also discussed.
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Affiliation(s)
- Hélène Sanfaçon
- Agriculture and Agri-Food Canada, Pacific Agri-Food Research Centre, 4200 Highway 97, Summerland, BC V0H 1Z0, Canada (e-mail: )
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Thivierge K, Nicaise V, Dufresne PJ, Cotton S, Laliberté JF, Le Gall O, Fortin MG. Plant virus RNAs. Coordinated recruitment of conserved host functions by (+) ssRNA viruses during early infection events. PLANT PHYSIOLOGY 2005; 138:1822-7. [PMID: 16172095 PMCID: PMC1183374 DOI: 10.1104/pp.105.064105] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Positive-sense single-stranded RNA viruses have developed strategies to exploit cellular resources at the expense of host mRNAs. The genomes of these viruses display a variety of structures at their 5' and 3' ends that differentiate them from cellular mRNAs. Despite this structural diversity, viral RNAs are still circularized by juxtaposition of their 5' and 3' ends, similar to the process used by cellular mRNAs. Also reminiscent of the mechanisms used by host mRNAs, translation of viral RNAs involves the recruitment of translation initiation factors. However, the roles played by these factors likely differ from those played by cellular mRNAs. In keeping with the general parsimony typical of RNA viruses, these host factors also participate in viral RNA replication. However, the dual use of host factors requires that viral RNA template utilization be regulated to avoid conflict between replication and translation. The molecular composition of the large ribonucleoprotein complexes that form the viral RNA replication and translation machineries likely evolves over the course of infection to allow for switching template use from translation to replication.
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Affiliation(s)
- Karine Thivierge
- Department of Plant Science, McGill University, Ste-Anne-de-Bellevue, Canada H9X 3V9
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Snegireva PB, Istomina EA, Shiyan AN. A single reverse mutation in the 126/183-kDa replicase gene of the attenuated tomato strain V-69 of tobacco mosaic virus increases the virus pathogenicity. RUSS J GENET+ 2005. [DOI: 10.1007/s11177-005-0059-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Léonard S, Viel C, Beauchemin C, Daigneault N, Fortin MG, Laliberté JF. Interaction of VPg-Pro of turnip mosaic virus with the translation initiation factor 4E and the poly(A)-binding protein in planta. J Gen Virol 2004; 85:1055-1063. [PMID: 15039548 DOI: 10.1099/vir.0.19706-0] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The viral protein linked to the genome (VPg) of Turnip mosaic virus (TuMV) interacts in vitro with the translation eukaryotic initiation factor (eIF) 4E. In the present study, we investigated the consequence of TuMV infection on eIF4E expression. Two isomers are present in plants, namely eIF4E and eIF(iso)4E. Expression of the latter was detected in both TuMV-infected and mock-inoculated Brassica perviridis plants, but expression of eIF4E was found only in infected plants. Membranes from TuMV-infected or mock-inoculated tissues were separated by sucrose gradient centrifugation and fractions were collected. Immunoblot analyses showed that 6K(2)-VPg-Pro/VPg-Pro polyproteins were associated with endoplasmic reticulum membranes and were the viral forms likely to interact with eIF(iso)4E and eIF4E. In planta interaction between 6K(2)-VPg-Pro/VPg-Pro and eIF(iso)4E/eIF4E was confirmed by co-purification by metal chelation chromatography. The poly(A)-binding protein (PABP) was also found to co-purify with VPg-Pro. Direct interaction between VPg-Pro and PABP was shown by an ELISA-based binding assay. These experiments suggest that a multi-protein complex may form around VPg-Pro of TuMV.
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Affiliation(s)
- Simon Léonard
- Institut National de la Recherche Scientifique, Institut Armand-Frappier, 531 boulevard des Prairies, Laval, Québec, Canada H7V 1B7
| | - Catherine Viel
- Institut National de la Recherche Scientifique, Institut Armand-Frappier, 531 boulevard des Prairies, Laval, Québec, Canada H7V 1B7
| | - Chantal Beauchemin
- Institut National de la Recherche Scientifique, Institut Armand-Frappier, 531 boulevard des Prairies, Laval, Québec, Canada H7V 1B7
| | - Nicole Daigneault
- Institut National de la Recherche Scientifique, Institut Armand-Frappier, 531 boulevard des Prairies, Laval, Québec, Canada H7V 1B7
| | - Marc G Fortin
- Department of Plant Science, McGill University, 21 111 Lakeshore, Ste-Anne-de-Bellevue, Québec, Canada H9X 3V9
| | - Jean-François Laliberté
- Institut National de la Recherche Scientifique, Institut Armand-Frappier, 531 boulevard des Prairies, Laval, Québec, Canada H7V 1B7
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Chong JL, Chuang RY, Tung L, Chang TH. Ded1p, a conserved DExD/H-box translation factor, can promote yeast L-A virus negative-strand RNA synthesis in vitro. Nucleic Acids Res 2004; 32:2031-8. [PMID: 15064363 PMCID: PMC390370 DOI: 10.1093/nar/gkh519] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Viruses are intracellular parasites that must use the host machinery to multiply. Identification of the host factors that perform essential functions in viral replication is thus of crucial importance to the understanding of virus-host interactions. Here we describe Ded1p, a highly conserved DExD/H-box translation factor, as a possible host factor recruited by the yeast L-A double-stranded RNA (dsRNA) virus. We found that Ded1p interacts specifically and strongly with Gag, the L-A virus coat protein. Further analysis revealed that Ded1p interacts with the L-A virus in an RNA-independent manner and, as a result, L-A particles can be affinity purified via this interaction. The affinity-purified L-A particles are functional, as they are capable of synthesizing RNA in vitro. Critically, using purified L-A particles, we demonstrated that Ded1p specifically promotes L-A dsRNA replication by accelerating the rate of negative-strand RNA synthesis in vitro. In light of these data, we suggest that Ded1p may be a part of the long sought after activity shown to promote yeast viral dsRNA replication. This and the fact that Ded1p is also required for translating brome mosaic virus RNA2 in yeast thus raise the intriguing possibility that Ded1p is one of the key host factors favored by several evolutionarily related RNA viruses, including the human hepatitis C virus.
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Affiliation(s)
- Jean-Leon Chong
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
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Ahlquist P, Noueiry AO, Lee WM, Kushner DB, Dye BT. Host factors in positive-strand RNA virus genome replication. J Virol 2003; 77:8181-6. [PMID: 12857886 PMCID: PMC165243 DOI: 10.1128/jvi.77.15.8181-8186.2003] [Citation(s) in RCA: 375] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Affiliation(s)
- Paul Ahlquist
- Institute for Molecular Virology, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
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Knapp E, Lewandowski DJ. Tobacco mosaic virus, not just a single component virus anymore. MOLECULAR PLANT PATHOLOGY 2001; 2:117-123. [PMID: 20572999 DOI: 10.1046/j.1364-3703.2001.00064.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Summary Taxonomy: Tobacco mosaic virus (TMV) is the type species of the Tobamovirus genus and a member of the alphavirus-like supergroup. Historically, many tobamoviruses are incorrectly called strains of TMV, although they can differ considerably in sequence similarities and host range from each other and from TMV. Physical properties: TMV virions are 300 x 18 nm rods with a central hollow cavity (Fig. 1) and are composed of 95% capsid protein (CP), and 5% RNA. Each CP subunit interacts with 3-nts in a helical arrangement around the RNA. Virions are stable for decades; infectivity in sap survives heating to 90 degrees C. Hosts: The natural host range of TMV is limited; however, a broad range of weed and crop species, mostly Solanaceae that includes tobacco, pepper and tomato can be infected experimentally [Holmes, F.O. (1946) A comparison of the experimental host ranges of tobacco etch and tobacco mosaic viruses. Phytopathology, 36, 643-657]. TMV distribution is worldwide. No biological vectors are known. Useful website: http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/71010001.htm.
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Affiliation(s)
- E Knapp
- Department of Plant Pathology, University of Florida, Citrus Research and Education Center, Lake Alfred, FL 33850, USA
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