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Abstract
Cacao swollen shoot virus causes cacao swollen shoot disease of Theobroma cacao (cacao) plants. At least six cacao-infecting Badnavirus species-Cacao swollen shoot Togo A virus, Cacao swollen shoot Togo B virus (previously known as Cacao swollen shoot virus), Cacao swollen shoot CE virus, Cacao swollen shoot Ghana M virus, Cacao swollen shoot Ghana N virus, and Cacao swollen shoot Ghana Q virus-are responsible for the swollen shoot disease of cacao in Ghana. Each of these species consists of a multiplicity of strains. The New Juaben strain, the most virulent cacao swollen shoot virus strain in Ghana, belongs to the Cacao swollen shoot Togo B virus species, and is a commonly used strain in laboratory transmission assays. Infection of cacao trees with multiple strains of the virus is common and new evidence suggests that these coinfections may have resulted in the emergence of recombinant strains of the virus. The impact of these emerging recombinant strains on disease severity is uncertain. This review focuses largely on the discovery of cacao swollen shoot virus in Ghana, diversity of the virus strains, molecular characterization, propagation of virus infection in cacao plants, emergence of recombinant virus strains, vector-mediated transmission of the virus, and the management of the cacao swollen shoot disease in Ghana. It also contains sections on the botany and origin of the cacao tree, its introduction to Ghana, the role of cacao swollen shoot disease in facilitating Ghana's independence from Britain, and a brief history of chocolate.
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Affiliation(s)
| | - Owusu Domfeh
- Plant Pathology Division, Cocoa Research Institute of Ghana, New Tafo, Akim, Ghana
| | - George Akumfi Ameyaw
- Plant Pathology Division, Cocoa Research Institute of Ghana, New Tafo, Akim, Ghana
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2
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Pouresmaeil M, Dall'Ara M, Salvato M, Turri V, Ratti C. Cauliflower mosaic virus: Virus-host interactions and its uses in biotechnology and medicine. Virology 2023; 580:112-119. [PMID: 36812696 DOI: 10.1016/j.virol.2023.02.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 02/14/2023] [Accepted: 02/15/2023] [Indexed: 02/19/2023]
Abstract
Cauliflower mosaic virus (CaMV) was the first discovered plant virus with genomic DNA that uses reverse transcriptase for replication. The CaMV 35S promoter is a constitutive promoter and thus, an attractive driver of gene expression in plant biotechnology. It is used in most transgenic crops to activate foreign genes which have been artificially inserted into the host plant. In the last century, producing food for the world's population while preserving the environment and human health is the main topic of agriculture. The damage caused by viral diseases has a significant negative economic impact on agriculture, and disease control is based on two strategies: immunization and prevention to contain virus spread, so correct identification of plant viruses is important for disease management. Here, we discuss CaMV from different aspects: taxonomy, structure and genome, host plants and symptoms, transmission and pathogenicity, prevention, control and application in biotechnology as well as in medicine. Also, we calculated the CAI index for three ORFs IV, V, and VI of the CaMV virus in host plants, the results of which can be used in the discussion of gene transfer or antibody production to identify the CaMV.
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Affiliation(s)
- Mahin Pouresmaeil
- Department of Biotechnology, Faculty of Agriculture, Azarbijan Shahid Madani University, Tabriz, Iran.
| | - Mattia Dall'Ara
- Department of Agricultural and Food Sciences, School of Agriculture and Veterinary Medicine, University of Bologna, 40127, Bologna, Italy
| | - Maria Salvato
- University of Maryland, Department of Veterinary Medicine, College Park, MD, 20742, USA
| | - Valentina Turri
- Healthcare Direction, Istituto Scientifico Romagnolo per Lo Studio e La Cura Dei Tumori, IRCCS, 47014, Meldola, FC, Italy
| | - Claudio Ratti
- Department of Agricultural and Food Sciences, School of Agriculture and Veterinary Medicine, University of Bologna, 40127, Bologna, Italy
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3
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Kubina J, Geldreich A, Gales JP, Baumberger N, Bouton C, Ryabova LA, Grasser KD, Keller M, Dimitrova M. Nuclear export of plant pararetrovirus mRNAs involves the TREX complex, two viral proteins and the highly structured 5' leader region. Nucleic Acids Res 2021; 49:8900-8922. [PMID: 34370034 PMCID: PMC8421220 DOI: 10.1093/nar/gkab653] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Revised: 07/09/2021] [Accepted: 07/22/2021] [Indexed: 11/13/2022] Open
Abstract
In eukaryotes, the major nuclear export pathway for mature mRNAs uses the dimeric receptor TAP/p15, which is recruited to mRNAs via the multisubunit TREX complex, comprising the THO core and different export adaptors. Viruses that replicate in the nucleus adopt different strategies to hijack cellular export factors and achieve cytoplasmic translation of their mRNAs. No export receptors are known in plants, but Arabidopsis TREX resembles the mammalian complex, with a conserved hexameric THO core associated with ALY and UIEF proteins, as well as UAP56 and MOS11. The latter protein is an orthologue of mammalian CIP29. The nuclear export mechanism for viral mRNAs has not been described in plants. To understand this process, we investigated the export of mRNAs of the pararetrovirus CaMV in Arabidopsis and demonstrated that it is inhibited in plants deficient in ALY, MOS11 and/or TEX1. Deficiency for these factors renders plants partially resistant to CaMV infection. Two CaMV proteins, the coat protein P4 and reverse transcriptase P5, are important for nuclear export. P4 and P5 interact and co-localise in the nucleus with the cellular export factor MOS11. The highly structured 5′ leader region of 35S RNAs was identified as an export enhancing element that interacts with ALY1, ALY3 and MOS11 in vitro.
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Affiliation(s)
- Julie Kubina
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Angèle Geldreich
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Jón Pol Gales
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Nicolas Baumberger
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Clément Bouton
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Lyubov A Ryabova
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Klaus D Grasser
- Cell Biology & Plant Biochemistry, Biochemistry Centre, University of Regensburg, D-93053 Regensburg, Germany
| | - Mario Keller
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Maria Dimitrova
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
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4
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Mann KS, Sanfaçon H. Expanding Repertoire of Plant Positive-Strand RNA Virus Proteases. Viruses 2019; 11:v11010066. [PMID: 30650571 PMCID: PMC6357015 DOI: 10.3390/v11010066] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 01/11/2019] [Accepted: 01/12/2019] [Indexed: 12/13/2022] Open
Abstract
Many plant viruses express their proteins through a polyprotein strategy, requiring the acquisition of protease domains to regulate the release of functional mature proteins and/or intermediate polyproteins. Positive-strand RNA viruses constitute the vast majority of plant viruses and they are diverse in their genomic organization and protein expression strategies. Until recently, proteases encoded by positive-strand RNA viruses were described as belonging to two categories: (1) chymotrypsin-like cysteine and serine proteases and (2) papain-like cysteine protease. However, the functional characterization of plant virus cysteine and serine proteases has highlighted their diversity in terms of biological activities, cleavage site specificities, regulatory mechanisms, and three-dimensional structures. The recent discovery of a plant picorna-like virus glutamic protease with possible structural similarities with fungal and bacterial glutamic proteases also revealed new unexpected sources of protease domains. We discuss the variety of plant positive-strand RNA virus protease domains. We also highlight possible evolution scenarios of these viral proteases, including evidence for the exchange of protease domains amongst unrelated viruses.
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Affiliation(s)
- Krin S Mann
- Summerland Research and Development Centre, Agriculture and Agri-Food Canada, Summerland, BC V0H 1Z0, Canada.
| | - Hélène Sanfaçon
- Summerland Research and Development Centre, Agriculture and Agri-Food Canada, Summerland, BC V0H 1Z0, Canada.
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5
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Rodamilans B, Shan H, Pasin F, García JA. Plant Viral Proteases: Beyond the Role of Peptide Cutters. FRONTIERS IN PLANT SCIENCE 2018; 9:666. [PMID: 29868107 PMCID: PMC5967125 DOI: 10.3389/fpls.2018.00666] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 04/30/2018] [Indexed: 05/23/2023]
Abstract
Almost half of known plant viral species rely on proteolytic cleavages as key co- and post-translational modifications throughout their infection cycle. Most of these viruses encode their own endopeptidases, proteases with high substrate specificity that internally cleave large polyprotein precursors for the release of functional sub-units. Processing of the polyprotein, however, is not an all-or-nothing process in which endopeptidases act as simple peptide cutters. On the contrary, spatial-temporal modulation of these polyprotein cleavage events is crucial for a successful viral infection. In this way, the processing of the polyprotein coordinates viral replication, assembly and movement, and has significant impact on pathogen fitness and virulence. In this mini-review, we give an overview of plant viral proteases emphasizing their importance during viral infections and the varied functionalities that result from their proteolytic activities.
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Affiliation(s)
- Bernardo Rodamilans
- Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain
| | - Hongying Shan
- Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain
| | - Fabio Pasin
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan
| | - Juan Antonio García
- Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain
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6
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Geldreich A, Haas G, Kubina J, Bouton C, Tanguy M, Erhardt M, Keller M, Ryabova L, Dimitrova M. Formation of large viroplasms and virulence of Cauliflower mosaic virus in turnip plants depend on the N-terminal EKI sequence of viral protein TAV. PLoS One 2017; 12:e0189062. [PMID: 29253877 PMCID: PMC5734791 DOI: 10.1371/journal.pone.0189062] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 11/17/2017] [Indexed: 12/11/2022] Open
Abstract
Cauliflower mosaic virus (CaMV) TAV protein (TransActivator/Viroplasmin) plays a pivotal role during the infection cycle since it activates translation reinitiation of viral polycistronic RNAs and suppresses RNA silencing. It is also the major component of cytoplasmic electron-dense inclusion bodies (EDIBs) called viroplasms that are particularly evident in cells infected by the virulent CaMV Cabb B-JI isolate. These EDIBs are considered as virion factories, vehicles for CaMV intracellular movement and reservoirs for CaMV transmission by aphids. In this study, focused on different TAV mutants in vivo, we demonstrate that three physically separated domains collectively participate to the formation of large EDIBs: the N-terminal EKI motif, a sequence of the MAV domain involved in translation reinitiation and a C-terminal region encompassing the zinc finger. Surprisingly, EKI mutant TAVm3, corresponding to a substitution of the EKI motif at amino acids 11-13 by three alanines (AAA), which completely abolished the formation of large viroplasms, was not lethal for CaMV but highly reduced its virulence without affecting the rate of systemic infection. Expression of TAVm3 in a viral context led to formation of small irregularly shaped inclusion bodies, mild symptoms and low levels of viral DNA and particles accumulation, despite the production of significant amounts of mature capsid proteins. Unexpectedly, for CaMV-TAVm3 the formation of viral P2-containing electron-light inclusion body (ELIB), which is essential for CaMV aphid transmission, was also altered, thus suggesting an indirect role of the EKI tripeptide in CaMV plant-to-plant propagation. This important functional contribution of the EKI motif in CaMV biology can explain the strict conservation of this motif in the TAV sequences of all CaMV isolates.
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Affiliation(s)
- Angèle Geldreich
- Institut de Biologie Moléculaire des Plantes, CNRS UPR2357, Université de Strasbourg, Strasbourg, France
| | - Gabrielle Haas
- Institut de Biologie Moléculaire des Plantes, CNRS UPR2357, Université de Strasbourg, Strasbourg, France
| | - Julie Kubina
- Institut de Biologie Moléculaire des Plantes, CNRS UPR2357, Université de Strasbourg, Strasbourg, France
| | - Clément Bouton
- Institut de Biologie Moléculaire des Plantes, CNRS UPR2357, Université de Strasbourg, Strasbourg, France
| | - Mélanie Tanguy
- Institut de Biologie Moléculaire des Plantes, CNRS UPR2357, Université de Strasbourg, Strasbourg, France
| | - Mathieu Erhardt
- Institut de Biologie Moléculaire des Plantes, CNRS UPR2357, Université de Strasbourg, Strasbourg, France
| | - Mario Keller
- Institut de Biologie Moléculaire des Plantes, CNRS UPR2357, Université de Strasbourg, Strasbourg, France
| | - Lyubov Ryabova
- Institut de Biologie Moléculaire des Plantes, CNRS UPR2357, Université de Strasbourg, Strasbourg, France
| | - Maria Dimitrova
- Institut de Biologie Moléculaire des Plantes, CNRS UPR2357, Université de Strasbourg, Strasbourg, France
- * E-mail:
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7
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Schoelz JE, Leisner S. Setting Up Shop: The Formation and Function of the Viral Factories of Cauliflower mosaic virus. FRONTIERS IN PLANT SCIENCE 2017; 8:1832. [PMID: 29163571 PMCID: PMC5670102 DOI: 10.3389/fpls.2017.01832] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 10/10/2017] [Indexed: 05/23/2023]
Abstract
Similar to cells, viruses often compartmentalize specific functions such as genome replication or particle assembly. Viral compartments may contain host organelle membranes or they may be mainly composed of viral proteins. These compartments are often termed: inclusion bodies (IBs), viroplasms or viral factories. The same virus may form more than one type of IB, each with different functions, as illustrated by the plant pararetrovirus, Cauliflower mosaic virus (CaMV). CaMV forms two distinct types of IBs in infected plant cells, those composed mainly of the viral proteins P2 (which are responsible for transmission of CaMV by insect vectors) and P6 (required for viral intra-and inter-cellular infection), respectively. P6 IBs are the major focus of this review. Much of our understanding of the formation and function of P6 IBs comes from the analyses of their major protein component, P6. Over time, the interactions and functions of P6 have been gradually elucidated. Coupled with new technologies, such as fluorescence microscopy with fluorophore-tagged viral proteins, these data complement earlier work and provide a clearer picture of P6 IB formation. As the activities and interactions of the viral proteins have gradually been determined, the functions of P6 IBs have become clearer. This review integrates the current state of knowledge on the formation and function of P6 IBs to produce a coherent model for the activities mediated by these sophisticated virus-manufacturing machines.
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Affiliation(s)
- James E. Schoelz
- Division of Plant Sciences, University of Missouri, Columbia, MO, United States
| | - Scott Leisner
- Department of Biological Sciences, University of Toledo, Toledo, OH, United States
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8
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Vo JN, Campbell PR, Mahfuz NN, Ramli R, Pagendam D, Barnard R, Geering ADW. Characterization of the banana streak virus capsid protein and mapping of the immunodominant continuous B-cell epitopes to the surface-exposed N terminus. J Gen Virol 2016; 97:3446-3457. [DOI: 10.1099/jgv.0.000643] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Affiliation(s)
- Jenny N. Vo
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, GPO Box 267, Brisbane, Queensland 4001, Australia
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
- Plant Biosecurity Cooperative Research Centre, LPO Box 5012, Bruce, Australian Capital Territory 2617, Australia
| | - Paul R. Campbell
- Plant Biosecurity Cooperative Research Centre, LPO Box 5012, Bruce, Australian Capital Territory 2617, Australia
- Queensland Department of Agriculture, Fisheries and Forestry, GPO Box 267, Brisbane, Queensland 4001, Australia
| | - Nur N. Mahfuz
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Ras Ramli
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Daniel Pagendam
- CSIRO Mathematics, Informatics and Statistics, Ecosciences Precinct, 41 Boggo Road, Dutton Park, Queensland 4102, Australia
| | - Ross Barnard
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Andrew D. W. Geering
- Plant Biosecurity Cooperative Research Centre, LPO Box 5012, Bruce, Australian Capital Territory 2617, Australia
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, GPO Box 267, Brisbane, Queensland 4001, Australia
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9
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Hull R. Replication of Plant Viruses. PLANT VIROLOGY 2014. [PMCID: PMC7184227 DOI: 10.1016/b978-0-12-384871-0.00007-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Viruses replicate using both their own genetic information and host cell components and machinery. The different genome types have different replication pathways which contain controls on linking the process with translation and movement around the cell as well as not compromising the infected cell. This chapter discusses the replication mechanisms, faults in replication and replication of viruses co-infecting cells. Viruses replicate using both their own genetic information and host cell components and machinery. The different genome types have different replication pathways which contain controls on linking the process with translation and movement around the cell as well as not compromising the infected cell. This chapter discusses the replication mechanisms, faults in replication and replication of viruses coinfecting cells.
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10
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Hohn T, Rothnie H. Plant pararetroviruses: replication and expression. Curr Opin Virol 2013; 3:621-8. [PMID: 24063990 DOI: 10.1016/j.coviro.2013.08.013] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 08/26/2013] [Accepted: 08/26/2013] [Indexed: 02/07/2023]
Abstract
True retroviruses are not known in plants; however, plant pararetroviruses (caulimoviridae) share many retroviral properties, replicating by transcription in the nucleus followed by reverse transcription in the cytoplasm. Pararetroviruses have circular DNA genomes that do not integrate into the host genome, and display several unique expression strategies. Typical of plant pararetroviral pregenomic RNA is a highly structured leader of about 600nt long that is bypassed by scanning ribosomes. Caulimoviruses and Soymoviruses have a further interesting translation mechanism: at least six of the seven open reading frames are translated via polycistronic translation mediated by a specific transactivator (TAV), which modifies the translation complex. TAV also forms large intracellular inclusion bodies, which are the site of translation and virus assembly.
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Affiliation(s)
- Thomas Hohn
- Basel University, Botanical Institute, Basel, Switzerland.
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11
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Virus factories of cauliflower mosaic virus are virion reservoirs that engage actively in vector transmission. J Virol 2013; 87:12207-15. [PMID: 24006440 DOI: 10.1128/jvi.01883-13] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cauliflower mosaic virus (CaMV) forms two types of inclusion bodies within infected plant cells: numerous virus factories, which are the sites for viral replication and virion assembly, and a single transmission body (TB), which is specialized for virus transmission by aphid vectors. The TB reacts within seconds to aphid feeding on the host plant by total disruption and redistribution of its principal component, the viral transmission helper protein P2, onto microtubules throughout the cell. At the same time, virions also associate with microtubules. This redistribution of P2 and virions facilitates transmission and is reversible; the TB reforms within minutes after vector departure. Although some virions are present in the TB before disruption, their subsequent massive accumulation on the microtubule network suggests that they also are released from virus factories. Using drug treatments, mutant viruses, and exogenous supply of viral components to infected protoplasts, we show that virions can rapidly exit virus factories and, once in the cytoplasm, accumulate together with the helper protein P2 on the microtubule network. Moreover, we show that during reversion of this phenomenon, virions from the microtubule network can either be incorporated into the reverted TB or return to the virus factories. Our results suggest that CaMV factories are dynamic structures that participate in vector transmission by controlled release and uptake of virions during TB reaction.
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12
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Coat proteins, host factors and plant viral replication. Curr Opin Virol 2012; 2:712-8. [DOI: 10.1016/j.coviro.2012.10.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Revised: 09/28/2012] [Accepted: 10/01/2012] [Indexed: 11/24/2022]
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13
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Bak A, Irons SL, Martinière A, Blanc S, Drucker M. Host cell processes to accomplish mechanical and non-circulative virus transmission. PROTOPLASMA 2012; 249:529-39. [PMID: 21984344 DOI: 10.1007/s00709-011-0328-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Accepted: 09/28/2011] [Indexed: 05/22/2023]
Abstract
Mechanical vector-less transmission of viruses, as well as vector-mediated non-circulative virus transmission, where the virus attaches only to the exterior of the vector during the passage to a new host, are apparently simple processes: the viruses are carried along with the wind, the food or by the vector to a new host. We discuss here, using the examples of the non-circulatively transmitted Cauliflower mosaic virus that binds to its aphid vector's exterior mouthparts, and that of the mechanically (during feeding activity) transmitted Autographa californica multicapsid nucleopolyhedrovirus, that transmission of these viruses is not so simple as previously thought. Rather, these viruses prepare their transmission carefully and long before the actual acquisition event. Host-virus interactions play a pivotal and specialised role in the future encounter with the vector or the new host. This ensures optimal propagation and enlarges the tremendous bottleneck transmission presents for viruses and other pathogens.
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Affiliation(s)
- Aurélie Bak
- INRA, Equipe CaGeTE, UMR BGPI Plant Pathogen Interactions, TA A54K Campus International de Baillarguet, 34398, Montpellier Cedex 5, France
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14
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Zhang Y, Zhang X, Niu S, Han C, Yu J, Li D. Nuclear localization of Beet black scorch virus capsid protein and its interaction with importin α. Virus Res 2011; 155:307-15. [PMID: 21056066 DOI: 10.1016/j.virusres.2010.10.029] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Revised: 10/19/2010] [Accepted: 10/20/2010] [Indexed: 11/26/2022]
Abstract
Beet black scorch virus (BBSV) is a positive-sense, single-stranded RNA virus belonging to Necrovirus genus. In order to better understand the life cycle of BBSV, we have investigated the subcellular localization of BBSV capsid protein (CP) by its fusion with green fluorescent protein (GFP) agroinfiltrated into Nicotiana benthamiana leaves and by particle bombardment into onion (Allium cepa) epidermal cells. Confocal laser scanning microscopy (CLSM) showed that BBSV CP fused to GFP displayed enhanced fluorescence in nuclei and nuclear import of the CP was confirmed in BBSV-infected N. benthamiana leaves. Mutational analysis revealed that the N-terminal basic amino acid cluster (4)KRNKGGKKSR(13) of the CP is essential for nuclear localization. Bimolecular fluorescence complementation (BiFC) assays indicated that the CP could interact with the nuclear import factor importin α, suggesting that the CP is possibly imported into the nucleus via an importin α-dependent pathway. This is the first report of the nuclear localization of the CP encoded by a necrovirus.
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Affiliation(s)
- Yanjing Zhang
- State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China
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15
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Khelifa M, Massé D, Blanc S, Drucker M. Evaluation of the minimal replication time of Cauliflower mosaic virus in different hosts. Virology 2010; 396:238-45. [PMID: 19913268 DOI: 10.1016/j.virol.2009.09.032] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Revised: 08/02/2009] [Accepted: 09/26/2009] [Indexed: 11/22/2022]
Abstract
Though the duration of a single round of replication is an important biological parameter, it has been determined for only few viruses. Here, this parameter was determined for Cauliflower mosaic virus (CaMV) in transfected protoplasts from different hosts: the highly susceptible Arabidopsis and turnip, and Nicotiana benthamiana, where CaMV accumulates only slowly. Four methods of differing sensitivity were employed: labelling of (1) progeny DNA and (2) capsid protein, (3) immunocapture PCR,, and (4) progeny-specific PCR. The first progeny virus was detected about 21 h after transfection. This value was confirmed by all methods, indicating that our estimate was not biased by the sensitivity of the detection method, and approximated the actual time required for one round of CaMV replication. Unexpectedly, the replication kinetics were similar in the three hosts; suggesting that slow accumulation of CaMV in Nicotiana plants is determined by non-optimal interactions in other steps of the infection cycle.
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Affiliation(s)
- Mounia Khelifa
- Equipe CaGeTE, UMR 385 BGPI, INRA-CIRAD-SupAgro, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France
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16
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Champagne J, Laliberté-Gagné ME, Leclerc D. Phosphorylation of the termini of Cauliflower mosaic virus precapsid protein is important for productive infection. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2007; 20:648-58. [PMID: 17555273 DOI: 10.1094/mpmi-20-6-0648] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Cauliflower mosaic virus (CaMV) coat protein precursor (pre-CP) has 489 amino acids (p57) and is processed by the viral proteinase into three major forms: p44, p39, and p37. The N- and C-terminal extensions of pre-CP are released during maturation by the virus-encoded proteinase. We showed that these extensions are phosphorylated at several sites by host casein kinase II (CKII). We have identified the phosphorylated amino acids using an in vitro phosphorylation assay and tested the effect of mutation of these sites on viral infectivity. Mutation of serines S66, S68, and S72 to alanine in the N-terminal extension abolished phosphorylation of the protein in vitro. Also, mutation of all S and T residues in the C-terminus (450 to 489) made this region insensitive to CKII. Amino acid substitutions also were introduced into a full-length infectious clone of CaMV. Mutated forms of the virus with S66, S68, and S72 substituted with A or D showed a delay in symptom development and affected the infectivity of the virus. However, a mutant with an A substitution of all the S and T residues of the C-terminal extension of CP was not infectious. These results suggest that phosphorylation of the N- and C-termini of CaMV pre-CP plays an important role in the initiation of viral infection.
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Affiliation(s)
- Julie Champagne
- Centre de Recherche en Infectiologie, CHUQ, Pavilion CHUL, Québec G1V 4G2, Canada
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Krichevsky A, Kozlovsky SV, Gafni Y, Citovsky V. Nuclear import and export of plant virus proteins and genomes. MOLECULAR PLANT PATHOLOGY 2006; 7:131-146. [PMID: 20507434 DOI: 10.1111/j.1364-3703.2006.00321.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
SUMMARY Nuclear import and export are crucial processes for any eukaryotic cell, as they govern substrate exchange between the nucleus and the cytoplasm. Proteins involved in the nuclear transport network are generally conserved among eukaryotes, from yeast and fungi to animals and plants. Various pathogens, including some plant viruses, need to enter the host nucleus to gain access to its replication machinery or to integrate their DNA into the host genome; the newly replicated viral genomes then need to exit the nucleus to spread between host cells. To gain the ability to enter and exit the nucleus, these pathogens encode proteins that recognize cellular nuclear transport receptors and utilize the host's nuclear import and export pathways. Here, we review and discuss our current knowledge about the molecular mechanisms by which plant viruses find their way into and out of the host cell nucleus.
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Affiliation(s)
- Alexander Krichevsky
- Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY 11794-5215, USA
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Ballut L, Drucker M, Pugnière M, Cambon F, Blanc S, Roquet F, Candresse T, Schmid HP, Nicolas P, Gall OL, Badaoui S. HcPro, a multifunctional protein encoded by a plant RNA virus, targets the 20S proteasome and affects its enzymic activities. J Gen Virol 2005; 86:2595-2603. [PMID: 16099919 DOI: 10.1099/vir.0.81107-0] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The proteasome is a multicatalytic complex involved in many cellular processes in eukaryotes, such as protein and RNA turnover, cell division, signal transduction, transcription and translation. Intracellular pathogens are targets of its enzymic activities, and a number of animal viruses are known to interfere with these activities. The first evidence that a plant virus protein, the helper component-proteinase (HcPro) of Lettuce mosaic virus (LMV; genus Potyvirus), interferes with the 20S proteasome ribonuclease is reported here. LMV infection caused an aggregation of the 20S proteasome to high-molecular mass structures in vivo, and specific binding of HcPro to the proteasome was confirmed in vitro using two different approaches. HcPro inhibited the 20S endonuclease activity in vitro, while its proteolytic activities were unchanged or slightly stimulated. This ability of HcPro, a pathogenicity regulator of potyviruses, to interfere with some of the catalytic functions of the 20S proteasome suggests the existence of a novel type of defence and counter-defence interplay in the course of interaction between potyviruses and their hosts.
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Affiliation(s)
- Lionel Ballut
- UMR 1095 ASP (INRA-Université Blaise Pascal), Campus des Cézeaux, 24 Avenue des Landais, 63177 Aubière Cedex, France
| | - Martin Drucker
- UMR 385 BGPI, CIRAD-INRA-ENSAM, TA 41/K, Campus de Baillarguet, 34398 Montpellier Cedex 5, France
| | - Martine Pugnière
- CPBS, CNRS UMR 5160, Faculté de Pharmacie, 15 Av. Charles Flahault, 34093 Montpellier Cedex 5, France
| | - Florence Cambon
- UMR 1095 ASP (INRA-Université Blaise Pascal), Campus des Cézeaux, 24 Avenue des Landais, 63177 Aubière Cedex, France
| | - Stéphane Blanc
- UMR 385 BGPI, CIRAD-INRA-ENSAM, TA 41/K, Campus de Baillarguet, 34398 Montpellier Cedex 5, France
| | - Françoise Roquet
- CPBS, CNRS UMR 5160, Faculté de Pharmacie, 15 Av. Charles Flahault, 34093 Montpellier Cedex 5, France
| | - Thierry Candresse
- UMR GDPP (INRA-UVSB2), IBVM, BP 81, 33883 Villenave d'Ornon Cedex, France
| | - Hans-Peter Schmid
- UMR 1095 ASP (INRA-Université Blaise Pascal), Campus des Cézeaux, 24 Avenue des Landais, 63177 Aubière Cedex, France
| | - Paul Nicolas
- UMR 1095 ASP (INRA-Université Blaise Pascal), Campus des Cézeaux, 24 Avenue des Landais, 63177 Aubière Cedex, France
| | - Olivier Le Gall
- UMR GDPP (INRA-UVSB2), IBVM, BP 81, 33883 Villenave d'Ornon Cedex, France
| | - Saloua Badaoui
- UMR 1095 ASP (INRA-Université Blaise Pascal), Campus des Cézeaux, 24 Avenue des Landais, 63177 Aubière Cedex, France
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Guerra-Peraza O, Kirk D, Seltzer V, Veluthambi K, Schmit AC, Hohn T, Herzog E. Coat proteins of Rice tungro bacilliform virus and Mungbean yellow mosaic virus contain multiple nuclear-localization signals and interact with importin alpha. J Gen Virol 2005; 86:1815-1826. [PMID: 15914861 DOI: 10.1099/vir.0.80920-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Transport of the viral genome into the nucleus is an obligatory step in the replication cycle of plant pararetro- and geminiviruses. In both these virus types, the multifunctional coat protein (CP) is thought to be involved in this process. Here, a green fluorescent protein tagging approach was used to demonstrate nuclear import of the CPs of Rice tungro bacilliform virus (RTBV) and Mungbean yellow mosaic virus--Vigna (MYMV) in Nicotiana plumbaginifolia protoplasts. In both cases, at least two nuclear localization signals (NLSs) were identified and characterized. The NLSs of RTBV CP are located within both N- and C-terminal regions (residues 479KRPK/497KRK and 744KRK/758RRK), and those of MYMV CP within the N-terminal part (residues 3KR and 41KRRR). The MYMV and RTBV CP NLSs resemble classic mono- and bipartite NLSs, respectively. However, the N-terminal MYMV CP NLS and both RTBV CP NLSs show peculiarities in the number and position of basic residues. In vitro pull-down assays revealed interaction of RTBV and MYMV CPs with the nuclear import factor importin alpha, suggesting that both CPs are imported into the nucleus via an importin alpha-dependent pathway. The possibility that this pathway could serve for docking of virions to the nucleus is discussed.
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Affiliation(s)
- O Guerra-Peraza
- Friedrich Miescher Institute, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - D Kirk
- Friedrich Miescher Institute, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - V Seltzer
- Institut de Biologie Moléculaire des Plantes, UPR-CNRS 2357, Université Louis Pasteur, 12 rue du Général Zimmer, 67084 Strasbourg Cedex, France
| | - K Veluthambi
- Department of Plant Biotechnology, School of Biotechnology, Madurai Kamaraj University, Madurai 625021, India
| | - A C Schmit
- Department of Plant Biotechnology, School of Biotechnology, Madurai Kamaraj University, Madurai 625021, India
| | - T Hohn
- University of Basel, Botanical Institute, Plant Health Unit, Schoenbeinstrasse 6, 4056 Basel, Switzerland
- Friedrich Miescher Institute, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - E Herzog
- Department of Plant Biotechnology, School of Biotechnology, Madurai Kamaraj University, Madurai 625021, India
- Friedrich Miescher Institute, Maulbeerstrasse 66, 4058 Basel, Switzerland
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Abstract
In a eukaryotic cell, the nuclear envelope (NE) separates genetic information from the environment of biosynthesis and metabolism. Transfer of macromolecules across the NE involves the nuclear pores--large multisubunit protein complexes--and machinery that facilitates rapid, directional, and selective transport. While core elements of the transport process are conserved between kingdoms, different solutions to similar problems have also evolved. Although the structure and composition of the yeast and mammalian nuclear pore have been unraveled recently, the plant nuclear pore remains largely enigmatic. Like any other process, nucleocytoplasmic transport can be regulated. Several examples from plants are discussed that promise insights into the regulation of signaling pathways. While controlling the partitioning of cellular components, the nuclear envelope also presents an obstacle to viruses and transforming agents that need access to the genome, and different mechanisms have evolved to overcome this obstacle. Finally, the recent recognition of the importance of small RNAs for gene regulation emphasizes the need to understand small RNA nuclear export and the levels of its regulation. This review attempts to wed our molecular-mechanistic understanding of nucleocytoplasmic trafficking drawn from all model systems with the intriguing examples of regulated nucleocytoplasmic partitioning in plants.
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Affiliation(s)
- Iris Meier
- Plant Biotechnology Center and Department of Plant Cellular and Molecular Biology, The Ohio State University, Columbus, Ohio 43210, USA
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Froissart R, Uzest M, Ruiz-Ferrer V, Drucker M, Hébrard E, Hohn T, Blanc S. Splicing of Cauliflower mosaic virus 35S RNA serves to downregulate a toxic gene product. J Gen Virol 2004; 85:2719-2726. [PMID: 15302965 DOI: 10.1099/vir.0.80029-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Alternative splicing usually leads to an increase in the number of gene products that can be derived from a single transcript. Here, a different and novel use of alternative splicing – as a means to control the amount of a potentially toxic gene product in the plant pararetrovirus Cauliflower mosaic virus (CaMV) – is reported. About 70 % of the CaMV 35S RNA, which serves as a substrate for both reverse transcription and polycistronic mRNA, is spliced into four additional RNA species. Splicing occurs between four donor sites – one in the 5′ untranslated region and three within open reading frame (ORF) I – and one unique acceptor site at position 1508 in ORF II. A previous study revealed that the acceptor site is vital for CaMV infectivity and expression of ORFs III and IV from one of the spliced RNA species suggested that splicing may facilitate expression of downstream CaMV ORFs. However, it is shown here that deleting the splice acceptor site and replacing ORF II with a cargo ORF that lacks splice acceptor sites does not interfere with virus proliferation. Furthermore, it is demonstrated that whenever P2 cannot accumulate in infected tissues, the splice acceptor site at position 1508 is no longer vital and has little effect on virus replication. This suggests that the vital role of splicing in CaMV is regulation of P2 expression and that P2 exhibits biological properties that, whilst indispensable for virus–vector interactions, can block in planta virus infection if this regulation is abolished.
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Affiliation(s)
- Rémy Froissart
- UMR BGPI, CIRAD-INRA-ENSAM, TA 41/K, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France
| | - Maryline Uzest
- UMR BGPI, CIRAD-INRA-ENSAM, TA 41/K, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France
| | - Virginia Ruiz-Ferrer
- UMR BGPI, CIRAD-INRA-ENSAM, TA 41/K, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France
| | - Martin Drucker
- UMR BGPI, CIRAD-INRA-ENSAM, TA 41/K, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France
| | - Eugénie Hébrard
- UMR BGPI, CIRAD-INRA-ENSAM, TA 41/K, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France
| | - Thomas Hohn
- Friedrich Miescher Institut, PO Box 2543, CH-4002 Basel, Switzerland
| | - Stéphane Blanc
- UMR BGPI, CIRAD-INRA-ENSAM, TA 41/K, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France
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Champagne J, Benhamou N, Leclerc D. Localization of the N-terminal domain of cauliflower mosaic virus coat protein precursor. Virology 2004; 324:257-62. [PMID: 15207613 DOI: 10.1016/j.virol.2004.04.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2004] [Accepted: 04/22/2004] [Indexed: 10/26/2022]
Abstract
Cauliflower mosaic virus (CaMV) open reading frame (ORF) IV encodes a coat protein precursor (pre-CP) harboring an N-terminal extension that is cleaved off by the CaMV-encoded protease. In transfected cells, pre-CP is present in the cytoplasm, while the processed form (p44) of CP is targeted to the nucleus, suggesting that the N-terminal extension might be involved in keeping the pre-CP in the cytoplasm for viral assembly. This study reports for the first time the intracellular localization of the N-terminal extension during CaMV infection in Brassica rapa. Immunogold-labeling electron microscopy using polyclonal antibodies directed to the N-terminal extension of the pre-CP revealed that this region is closely associated with viral particles present in small aggregates, which we called small bodies, adjacent to the main inclusion bodies typical of CaMV infection. Based on these results, we propose a model for viral assembly of CaMV.
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Affiliation(s)
- Julie Champagne
- Centre de Recherche en Infectiologie, CHUQ, Pavillon CHUL, Quebec, Canada G1V 4G2.
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Haas M, Bureau M, Geldreich A, Yot P, Keller M. Cauliflower mosaic virus: still in the news. MOLECULAR PLANT PATHOLOGY 2002; 3:419-29. [PMID: 20569349 DOI: 10.1046/j.1364-3703.2002.00136.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
SUMMARY Taxonomic relationship: Cauliflower mosaic virus (CaMV) is the type member of the Caulimovirus genus in the Caulimoviridae family, which comprises five other genera. CaMV replicates its DNA genome by reverse transcription of a pregenomic RNA and thus belongs to the pararetrovirus supergroup, which includes the Hepadnaviridae family infecting vertebrates. Physical properties: Virions are non-enveloped isometric particles, 53 nm in diameter (Fig. 1). They are constituted by 420 capsid protein subunits organized following T= 7 icosahedral symmetry (Cheng, R.H., Olson, N.H. and Baker, T.S. (1992) Cauliflower mosaic virus: a 420 subunit (T= 7), multilayer structure. Virology, 16, 655-668). The genome consists of a double-stranded circular DNA of approximately 8000 bp that is embedded in the inner surface of the capsid. Viral proteins: The CaMV genome encodes six proteins, a cell-to-cell movement protein (P1), two aphid transmission factors (P2 and P3), the precursor of the capsid proteins (P4), a polyprotein precursor of proteinase, reverse transcriptase and ribonuclease H (P5) and an inclusion body protein/translation transactivator (P6). Hosts: The host range of CaMV is limited to plants of the Cruciferae family, i.e. Brassicae species and Arabidopsis thaliana, but some viral strains can also infect solanaceous plants. In nature, CaMV is transmitted by aphids in a non-circulative manner.
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Affiliation(s)
- Muriel Haas
- Institut de Biologie Moléculaire des Plantes CNRS, Université Louis Pasteur, 12 rue du Général Zimmer, 67084 Strasbourg Cedex, France
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