1
|
Xue M, Arvy N, German‐Retana S. The mystery remains: How do potyviruses move within and between cells? MOLECULAR PLANT PATHOLOGY 2023; 24:1560-1574. [PMID: 37571979 PMCID: PMC10632792 DOI: 10.1111/mpp.13383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 07/06/2023] [Accepted: 07/25/2023] [Indexed: 08/13/2023]
Abstract
The genus Potyvirus is considered as the largest among plant single-stranded (positive-sense) RNA viruses, causing considerable economic damage to vegetable and fruit crops worldwide. Through the coordinated action of four viral proteins and a few identified host factors, potyviruses exploit the endomembrane system of infected cells for their replication and for their intra- and intercellular movement to and through plasmodesmata (PDs). Although a significant amount of data concerning potyvirus movement has been published, no synthetic review compiling and integrating all information relevant to our current understanding of potyvirus transport is available. In this review, we highlight the complexity of potyvirus movement pathways and present three potential nonexclusive mechanisms based on (1) the use of the host endomembrane system to produce membranous replication vesicles that are targeted to PDs and move from cell to cell, (2) the movement of extracellular viral vesicles in the apoplasm, and (3) the transport of virion particles or ribonucleoprotein complexes through PDs. We also present and discuss experimental data supporting these different models as well as the aspects that still remain mostly speculative.
Collapse
Affiliation(s)
- Mingshuo Xue
- Univ. Bordeaux, INRAE, UMR 1332 Biologie du fruit et PathologieVillenave d'Ornon CedexFrance
| | - Nathalie Arvy
- Univ. Bordeaux, INRAE, UMR 1332 Biologie du fruit et PathologieVillenave d'Ornon CedexFrance
| | - Sylvie German‐Retana
- Univ. Bordeaux, INRAE, UMR 1332 Biologie du fruit et PathologieVillenave d'Ornon CedexFrance
| |
Collapse
|
2
|
Bwalya J, Kim KH. The Crucial Role of Chloroplast-Related Proteins in Viral Genome Replication and Host Defense against Positive-Sense Single-Stranded RNA Viruses. THE PLANT PATHOLOGY JOURNAL 2023; 39:28-38. [PMID: 36760047 PMCID: PMC9929168 DOI: 10.5423/ppj.rw.10.2022.0139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 12/19/2022] [Accepted: 12/22/2022] [Indexed: 06/18/2023]
Abstract
Plant viruses are responsible for worldwide production losses of numerous economically important crops. The most common plant RNA viruses are positivesense single-stranded RNA viruses [(+)ss RNA viruses]. These viruses have small genomes that encode a limited number of proteins. The viruses depend on their host's machinery for the replication of their RNA genome, assembly, movement, and attraction to the vectors for dispersal. Recently researchers have reported that chloroplast proteins are crucial for replicating (+)ss plant RNA viruses. Some chloroplast proteins, including translation initiation factor [eIF(iso)4E] and 75 DEAD-box RNA helicase RH8, help viruses fulfill their infection cycle in plants. In contrast, other chloroplast proteins such as PAP2.1, PSaC, and ATPsyn-α play active roles in plant defense against viruses. This is also consistent with the idea that reactive oxygen species, salicylic acid, jasmonic acid, and abscisic acid are produced in chloroplast. However, knowledge of molecular mechanisms and functions underlying these chloroplast host factors during the virus infection is still scarce and remains largely unknown. Our review briefly summarizes the latest knowledge regarding the possible role of chloroplast in plant virus replication, emphasizing chloroplast-related proteins. We have highlighted current advances regarding chloroplast-related proteins' role in replicating plant (+)ss RNA viruses.
Collapse
Affiliation(s)
- John Bwalya
- Department of Agriculture Biotechnology, College of Agriculture and Life Sciences, Seoul National University, Seoul 08826,
Korea
| | - Kook-Hyung Kim
- Department of Agriculture Biotechnology, College of Agriculture and Life Sciences, Seoul National University, Seoul 08826,
Korea
- Plant Genomics and Breeding Institute, Seoul National University, Seoul 08826,
Korea
- Research of Institute Agriculture and Life Sciences, Seoul National University, Seoul 08826,
Korea
| |
Collapse
|
3
|
Oberemok V, Laikova K, Golovkin I, Kryukov L, Kamenetsky-Goldstein R. Biotechnology of virus eradication and plant vaccination in phytobiome context. PLANT BIOLOGY (STUTTGART, GERMANY) 2022; 24:3-8. [PMID: 34569131 DOI: 10.1111/plb.13338] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 08/18/2021] [Indexed: 06/13/2023]
Abstract
A plant's associated biota plays an integral role in its metabolism, nutrient uptake, stress tolerance, pathogen resistance and other physiological processes. Although a virome is an integral part of the phytobiome, a major contradiction exists between the holobiont approach and the practical need to eradicate pathogens from agricultural crops. In this review, we discuss grapevine virus control, but the issue is also relevant for numerous other crops, including potato, cassava, citrus, cacao and other species. Grapevine diseases, especially viral infections, cause main crop losses. Methods have been developed to eliminate viruses and other microorganisms from plant material, but elimination of viruses from plant material does not guarantee protection from future reinfection. Elimination of viral particles in plant material could create genetic drift, leading in turn to an increase in the occurrence of pathogenic strains of viruses. A possible solution may be a combination of virus elimination and plant propagation in tissue culture with in vitro vaccination. In this context, possible strategies to control viral infections include application of plant resistance inducers, cross protection and vaccination using siRNA, dsRNA and viral replicons during plant 'cleaning' and in vitro propagation. The experience and knowledge accumulated in human immunization can help plant scientists to develop and employ new methods of protection, leading to more sustainable and healthier crop production.
Collapse
Affiliation(s)
- V Oberemok
- V.I. Vernadsky Crimean Federal University, Simferopol, Russia
- Nikita Botanical Gardens - National Scientific Centre Russian Academy of Sciences, Yalta, Russia
| | - K Laikova
- V.I. Vernadsky Crimean Federal University, Simferopol, Russia
- Research Institute of Agriculture of Crimea, Simferopol, Russia
| | - I Golovkin
- V.I. Vernadsky Crimean Federal University, Simferopol, Russia
| | - L Kryukov
- V.I. Vernadsky Crimean Federal University, Simferopol, Russia
- Lobachevsky State University of Nizhni Novgorod, Nizhni Novgorod, Russia
| | | |
Collapse
|
4
|
Agaoua A, Bendahmane A, Moquet F, Dogimont C. Membrane Trafficking Proteins: A New Target to Identify Resistance to Viruses in Plants. PLANTS 2021; 10:plants10102139. [PMID: 34685948 PMCID: PMC8541145 DOI: 10.3390/plants10102139] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 09/27/2021] [Accepted: 10/05/2021] [Indexed: 11/16/2022]
Abstract
Replication cycles from most simple-stranded positive RNA viruses infecting plants involve endomembrane deformations. Recent published data revealed several interactions between viral proteins and plant proteins associated with vesicle formation and movement. These plant proteins belong to the COPI/II, SNARE, clathrin and ESCRT endomembrane trafficking mechanisms. In a few cases, variations of these plant proteins leading to virus resistance have been identified. In this review, we summarize all known interactions between these plant cell mechanisms and viruses and highlight strategies allowing fast identification of variant alleles for membrane-associated proteins.
Collapse
Affiliation(s)
- Aimeric Agaoua
- INRAE Génétique et Amélioration des Fruits et Légumes (GAFL), 84140 Montfavet, France;
| | - Abdelhafid Bendahmane
- Institute of Plant Sciences-Paris-Saclay (IPS2), Université Paris-Saclay, INRAE, CNRS, Univ Evry, 91405 Orsay, France;
| | | | - Catherine Dogimont
- INRAE Génétique et Amélioration des Fruits et Légumes (GAFL), 84140 Montfavet, France;
- Correspondence:
| |
Collapse
|
5
|
The RNA-Dependent RNA Polymerase NIb of Potyviruses Plays Multifunctional, Contrasting Roles during Viral Infection. Viruses 2020; 12:v12010077. [PMID: 31936267 PMCID: PMC7019339 DOI: 10.3390/v12010077] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 12/28/2019] [Accepted: 01/03/2020] [Indexed: 12/14/2022] Open
Abstract
Potyviruses represent the largest group of known plant RNA viruses and include many agriculturally important viruses, such as Plum pox virus, Soybean mosaic virus, Turnip mosaic virus, and Potato virus Y. Potyviruses adopt polyprotein processing as their genome expression strategy. Among the 11 known viral proteins, the nuclear inclusion protein b (NIb) is the RNA-dependent RNA polymerase responsible for viral genome replication. Beyond its principal role as an RNA replicase, NIb has been shown to play key roles in diverse virus–host interactions. NIb recruits several host proteins into the viral replication complexes (VRCs), which are essential for the formation of functional VRCs for virus multiplication, and interacts with the sumoylation pathway proteins to suppress NPR1-mediated immunity response. On the other hand, NIb serves as a target of selective autophagy as well as an elicitor of effector-triggered immunity, resulting in attenuated virus infection. These contrasting roles of NIb provide an excellent example of the complex co-evolutionary arms race between plant hosts and potyviruses. This review highlights the current knowledge about the multifunctional roles of NIb in potyvirus infection, and discusses future research directions.
Collapse
|
6
|
Ruiz-Ramón F, Sempere RN, Méndez-López E, Sánchez-Pina MA, Aranda MA. Second generation of pepino mosaic virus vectors: improved stability in tomato and a wide range of reporter genes. PLANT METHODS 2019; 15:58. [PMID: 31149024 PMCID: PMC6537163 DOI: 10.1186/s13007-019-0446-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 05/23/2019] [Indexed: 06/09/2023]
Abstract
BACKGROUND Vectors based on plant viruses are important tools for functional genomics, cellular biology, plant genome engineering and molecular farming. We previously reported on the construction of PepGFP2a, a viral vector based on pepino mosaic virus (PepMV) which expressed GFP efficiently and stably in plants of its experimental host Nicotiana benthamiana, but not in its natural host tomato. We have prepared a new set of PepMV-based vectors with improved stability that are able to express a wide range of reporter genes, useful for both N. benthamiana and tomato. RESULTS We first tested PepGFPm1 and PepGFPm2, two variants of PepGFP2a in which we progressively reduced a duplication of nucleotides encoding the N-terminal region of the coat protein. The new vectors had improved GFP expression levels and stability in N. benthamiana but not in tomato plants. Next, we replaced GFP by DsRed or mCherry in the new vectors PepDsRed and PepmCherry, respectively; while PepmCherry behaved similarly to PepGFPm2, PepDsRed expressed the reporter gene efficiently also in tomato plants. We then used PepGFPm2 and PepDsRed to study the PepMV localization in both N. benthamiana and tomato cells. Using confocal laser scanning microscopy (CLSM), we observed characteristic fluorescent bodies in PepMV-infected cells; these bodies had a cytoplasmic localization and appeared in close proximity to the cell nucleus. Already at 3 days post-agroinoculation there were fluorescent bodies in almost every cell of agroinoculated tissues of both hosts, and always one body per cell. When markers for the endoplasmic reticulum or the Golgi apparatus were co-expressed with PepGFPm2 or PepDsRed, a reorganisation of these organelles was observed, with images suggesting that both are intimately related but not the main constituents of the PepMV bodies. Altogether, this set of data suggested that the PepMV bodies are similar to the potato virus X (PVX) "X-bodies", which have been described as the PVX viral replication complexes (VRCs). To complete the set of PepMV-based vectors, we constructed a vector expressing the BAR herbicide resistance gene, useful for massive susceptibility screenings. CONCLUSIONS We have significantly expanded the PepMV tool box by producing a set of new vectors with improved stability and efficiency in both N. benthamiana and tomato plants. By using two of these vectors, we have described characteristic cellular bodies induced by PepMV infection; these bodies are likely the PepMV VRCs.
Collapse
Affiliation(s)
- Fabiola Ruiz-Ramón
- Present Address: R + D+I Department, Abiopep S.L., Murcia, Spain
- Centro de Edafología y Biología Aplicada del Segura (CEBAS), Consejo Superior de Investigaciones Científicas (CSIC), Murcia, Spain
| | | | - Eduardo Méndez-López
- Centro de Edafología y Biología Aplicada del Segura (CEBAS), Consejo Superior de Investigaciones Científicas (CSIC), Murcia, Spain
| | - M. Amelia Sánchez-Pina
- Centro de Edafología y Biología Aplicada del Segura (CEBAS), Consejo Superior de Investigaciones Científicas (CSIC), Murcia, Spain
| | - Miguel A. Aranda
- Centro de Edafología y Biología Aplicada del Segura (CEBAS), Consejo Superior de Investigaciones Científicas (CSIC), Murcia, Spain
| |
Collapse
|
7
|
Interaction of the intrinsically disordered C-terminal domain of the sesbania mosaic virus RNA-dependent RNA polymerase with the viral protein P10 in vitro: modulation of the oligomeric state and polymerase activity. Arch Virol 2019; 164:971-982. [PMID: 30721364 DOI: 10.1007/s00705-019-04163-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 01/09/2019] [Indexed: 12/13/2022]
Abstract
The RNA-dependent RNA polymerase (RdRp) of sesbania mosaic virus (SeMV) was previously shown to interact with the viral protein P10, which led to enhanced polymerase activity. In the present investigation, the equilibrium dissociation constant for the interaction between the two proteins was determined to be 0.09 µM using surface plasmon resonance, and the disordered C-terminal domain of RdRp was shown to be essential for binding to P10. The association with P10 brought about a change in the oligomeric state of RdRp, resulting in reduced aggregation and increased polymerase activity. Interestingly, unlike the wild-type RdRp, C-terminal deletion mutants (C del 43 and C del 72) were found to exist predominantly as monomers and were as active as the RdRp-P10 complex. Thus, either the deletion of the C-terminal disordered domain or its masking by binding to P10 results in the activation of polymerase activity. Further, deletion of the C-terminal 85 residues of RdRp resulted in complete loss of activity. Mutation of a conserved tyrosine (RdRp Y480) within motif E, located between 72 and 85 residues from the C-terminus of RdRp, rendered the protein inactive, demonstrating the importance of motif E in RNA synthesis in vitro.
Collapse
|
8
|
Xie L, Song XJ, Liao ZF, Wu B, Yang J, Zhang H, Hong J. Endoplasmic reticulum remodeling induced by Wheat yellow mosaic virus infection studied by transmission electron microscopy. Micron 2019; 120:80-90. [PMID: 30807983 DOI: 10.1016/j.micron.2019.01.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 01/16/2019] [Accepted: 01/22/2019] [Indexed: 11/28/2022]
Abstract
Plant virus was a kind of organism lived depending on infecting viable host cell and propagated their posterity by replicating its hereditary nucleotide, transcripting into protein, assembling protein and nucleotide into virion (Ortín and Parra, 2006; Sanfaçon, 2005). Viral infection usually induces remodeling of host cell, especially endoplasmic reticulum (ER) for generating membrane packed viral factory. During the infection of Bymovirus, a kind of membranous body (MB) was generated in host cells, which is thought as an ER aggregate. In present study we performed a study on Wheat yellow mosaic virus (WYMV) induced MB by several transmission electron microscopy (TEM) based methods, including cytological observation, component analysis by immuno-gold labeling and structural analysis by electron tomography (ET). WYMV infection induced at least two morphologies of MB, including the lamella dominated morphology (lamella-MB) looked like sprawling cirrus, and the tubule dominated morphology (tubule-MB) looked like latticed network. MB was verified composing of ER as revealed by immuno-gold labeling by antibody against endoplasmic reticulum (ER) retention signal as well as by detailed observation of MB construction modules as double layer membrane. By immuno-gold labeling, both two MB morphologies (lamella-MB and tubule-MB) had same components in viral derived protein and membrane origination (from ER). Structural analysis by ET reconstruction revealed the organization of ER in MB. Lamella-MB was composed of cesER like structures arranged irregularly whereas tubule-MB was composed of tubER like structures arranged regularly. This study provided insights into the structural details in how Bymovirus utilizing host membrane system.
Collapse
Affiliation(s)
- Li Xie
- Analysis Center of Agrobiology and Environmental Sciences, Zhejiang University, Hangzhou 310058, China.
| | - Xi-Jiao Song
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Ministry of Agriculture Key Laboratory of Biotechnology in Plant Protection, Zhejiang Provincial Key Laboratory of Plant Virology, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
| | - Zhen-Feng Liao
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Ministry of Agriculture Key Laboratory of Biotechnology in Plant Protection, Zhejiang Provincial Key Laboratory of Plant Virology, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
| | - Bin Wu
- Institute of plant protection, Shandong Academy of Agricultural Sciences, Jinan 250100, China.
| | - Jian Yang
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Ministry of Agriculture Key Laboratory of Biotechnology in Plant Protection, Zhejiang Provincial Key Laboratory of Plant Virology, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
| | - Hengmu Zhang
- State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Ministry of Agriculture Key Laboratory of Biotechnology in Plant Protection, Zhejiang Provincial Key Laboratory of Plant Virology, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
| | - Jian Hong
- Analysis Center of Agrobiology and Environmental Sciences, Zhejiang University, Hangzhou 310058, China.
| |
Collapse
|
9
|
Hong JS, Ju HJ. The Plant Cellular Systems for Plant Virus Movement. THE PLANT PATHOLOGY JOURNAL 2017; 33:213-228. [PMID: 28592941 PMCID: PMC5461041 DOI: 10.5423/ppj.rw.09.2016.0198] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2016] [Revised: 11/05/2016] [Accepted: 11/13/2016] [Indexed: 05/24/2023]
Abstract
Plasmodesmata (PDs) are specialized intercellular channels that facilitate the exchange of various molecules, including sugars, ribonucleoprotein complexes, transcription factors, and mRNA. Their diameters, estimated to be 2.5 nm in the neck region, are too small to transfer viruses or viral genomes. Tobacco mosaic virus and Potexviruses are the most extensively studied viruses. In viruses, the movement protein (MP) is responsible for the PD gating that allows the intercellular movement of viral genomes. Various host factors interact with MP to regulate complicated mechanisms related to PD gating. Virus replication and assembly occur in viral replication complex (VRC) with membrane association, especially in the endoplasmic reticulum. VRC have a highly organized structure and are highly regulated by interactions among the various host factors, proteins encoded by the viral genome, and the viral genome. Virus trafficking requires host machineries, such as the cytoskeleton and the secretory systems. MP facilitates the virus replication and movement process. Despite the current level of understanding of virus movement, there are still many unknown and complex interactions between virus replication and virus movement. While numerous studies have been conducted to understand plant viruses with regards to cell-to-cell movement and replication, there are still many knowledge gaps. To study these interactions, adequate research tools must be used such as molecular, and biochemical techniques. Without such tools, virologists will not be able to gain an accurate or detailed understanding of the virus infection process.
Collapse
Affiliation(s)
- Jin-Sung Hong
- Department of Applied Biology, College of Agriculture and Life Sciences, Kangwon National University, Chuncheon 24341, Korea
| | - Ho-Jong Ju
- Department of Agricultural Biology, College of Agricultural Life Science, Chonbuk National University, Jeonju 54896, Korea
- Plant Medicinal Research Center, College of Agricultural Life Science, Chonbuk National University, Jeonju 54896, Korea
| |
Collapse
|
10
|
Characterization of a Non-Canonical Signal Peptidase Cleavage Site in a Replication Protein from Tomato Ringspot Virus. PLoS One 2016; 11:e0162223. [PMID: 27589230 PMCID: PMC5010249 DOI: 10.1371/journal.pone.0162223] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 08/18/2016] [Indexed: 11/19/2022] Open
Abstract
The NTB-VPg polyprotein from tomato ringspot virus is an integral membrane replication protein associated with endoplasmic reticulum membranes. A signal peptidase (SPase) cleavage was previously detected in the C-terminal region of NTB-VPg downstream of a 14 amino acid (aa)-long hydrophobic region (termed TM2). However, the exact location of the cleavage site was not determined. Using in vitro translation assays, we show that the SPase cleavage site is conserved in the NTB-VPg protein from various ToRSV isolates, although the rate of cleavage varies from one isolate to another. Systematic site-directed mutagenesis of the NTB-VPg SPase cleavage sites of two ToRSV isolates allowed the identification of sequences that affect cleavage efficiency. We also present evidence that SPase cleavage in the ToRSV-Rasp2 isolate occurs within a GAAGG sequence likely after the AAG (GAAG/G). Mutation of a downstream MAAV sequence to AAAV resulted in SPase cleavage at both the natural GAAG/G and the mutated AAA/V sequences. Given that there is a distance of seven aa between the two cleavage sites, this indicates that there is flexibility in the positioning of the cleavage sites relative to the inner surface of the membrane and the SPase active site. SPase cleavage sites are typically located 3–7 aa downstream of the hydrophobic region. However, the NTB-VPg GAAG/G cleavage site is located 17 aa downstream of the TM2 hydrophobic region, highlighting unusual features of the NTB-VPg SPase cleavage site. A putative 11 aa-long amphipathic helix was identified immediately downstream of the TM2 region and five aa upstream of the GAAG/G cleavage site. Based on these results, we present an updated topology model in which the hydrophobic and amphipathic domains form a long tilted helix or a bent helix in the membrane lipid bilayer, with the downstream cleavage site(s) oriented parallel to the membrane inner surface.
Collapse
|
11
|
How does the genome structure and lifestyle of a virus affect its population variation? Curr Opin Virol 2014; 9:39-44. [DOI: 10.1016/j.coviro.2014.09.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 09/02/2014] [Accepted: 09/03/2014] [Indexed: 11/20/2022]
|
12
|
Wei T, Zhang C, Hou X, Sanfaçon H, Wang A. The SNARE protein Syp71 is essential for turnip mosaic virus infection by mediating fusion of virus-induced vesicles with chloroplasts. PLoS Pathog 2013; 9:e1003378. [PMID: 23696741 PMCID: PMC3656112 DOI: 10.1371/journal.ppat.1003378] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 04/05/2013] [Indexed: 11/18/2022] Open
Abstract
All positive-strand RNA viruses induce the biogenesis of cytoplasmic membrane-bound virus factories for viral genome multiplication. We have previously demonstrated that upon plant potyvirus infection, the potyviral 6K2 integral membrane protein induces the formation of ER-derived replication vesicles that subsequently target chloroplasts for robust genome replication. Here, we report that following the trafficking of the Turnip mosaic potyvirus (TuMV) 6K2 vesicles to chloroplasts, 6K2 vesicles accumulate at the chloroplasts to form chloroplast-bound elongated tubular structures followed by chloroplast aggregation. A functional actomyosin motility system is required for this process. As vesicle trafficking and fusion in planta are facilitated by a superfamily of proteins known as SNAREs (soluble N-ethylmaleimide-sensitive-factor attachment protein receptors), we screened ER-localized SNARES or SNARE-like proteins for their possible involvement in TuMV infection. We identified Syp71 and Vap27-1 that colocalize with the chloroplast-bound 6K2 complex. Knockdown of their expression using a Tobacco rattle virus (TRV)-based virus-induced gene silencing vector showed that Syp71 but not Vap27-1 is essential for TuMV infection. In Syp71-downregulated plant cells, the formation of 6K2-induced chloroplast-bound elongated tubular structures and chloroplast aggregates is inhibited and virus accumulation is significantly reduced, but the trafficking of the 6K2 vesicles from the ER to chloroplast is not affected. Taken together, these data suggest that Syp71 is a host factor essential for successful virus infection by mediating the fusion of the virus-induced vesicles with chloroplasts during TuMV infection.
Collapse
Affiliation(s)
- Taiyun Wei
- Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada
- Department of Biology, The University of Western Ontario, London, Ontario, Canada
| | - Changwei Zhang
- Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada
- Department of Biology, The University of Western Ontario, London, Ontario, Canada
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing , People's Republic of China
| | - Xilin Hou
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing , People's Republic of China
| | - Hélène Sanfaçon
- Pacific Agri-Food Research Centre, Agriculture and Agri-Food Canada, Summerland, British Columbia, Canada
| | - Aiming Wang
- Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada
- Department of Biology, The University of Western Ontario, London, Ontario, Canada
| |
Collapse
|
13
|
Linnik O, Liesche J, Tilsner J, Oparka KJ. Unraveling the structure of viral replication complexes at super-resolution. FRONTIERS IN PLANT SCIENCE 2013; 4:6. [PMID: 23386855 PMCID: PMC3560349 DOI: 10.3389/fpls.2013.00006] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Accepted: 01/09/2013] [Indexed: 05/20/2023]
Abstract
During infection, many RNA viruses produce characteristic inclusion bodies that contain both viral and host components. These structures were first described over a century ago and originally termed "X-bodies," as their function was not immediately appreciated. Whilst some inclusion bodies may represent cytopathic by-products of viral protein over-accumulation, X-bodies have emerged as virus "factories," quasi-organelles that coordinate diverse viral infection processes such as replication, protein expression, evasion of host defenses, virion assembly, and intercellular transport. Accordingly, they are now generally referred to as viral replication complexes (VRCs). We previously used confocal fluorescence microscopy to unravel the complex structure of X-bodies produced by Potato virus X (PVX). Here we used 3D-structured illumination (3D-SIM) super-resolution microscopy to map the PVX X-body at a finer scale. We identify a previously unrecognized membrane structure induced by the PVX "triple gene block" (TGB) proteins, providing new insights into the complex interplay between virus and host within the X-body.
Collapse
Affiliation(s)
- Olga Linnik
- Institute of Molecular Plant Sciences, University of EdinburghEdinburgh, UK
| | - Johannes Liesche
- Faculty of Life Sciences, University of CopenhagenFrederiksberg C, Denmark
| | - Jens Tilsner
- Biomedical Sciences Research Complex, University of St AndrewsFife, UK
- Cell and Molecular Sciences, The James Hutton InstituteDundee, UK
| | - Karl J. Oparka
- Institute of Molecular Plant Sciences, University of EdinburghEdinburgh, UK
- *Correspondence: Karl J. Oparka, Institute of Molecular Plant Sciences, University of Edinburgh, King’s Buildings, Mayfield Road, Edinburgh EH9 3JR, UK. e-mail:
| |
Collapse
|
14
|
Tilsner J, Linnik O, Wright KM, Bell K, Roberts AG, Lacomme C, Santa Cruz S, Oparka KJ. The TGB1 movement protein of Potato virus X reorganizes actin and endomembranes into the X-body, a viral replication factory. PLANT PHYSIOLOGY 2012; 158:1359-70. [PMID: 22253256 PMCID: PMC3291258 DOI: 10.1104/pp.111.189605] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Accepted: 01/13/2012] [Indexed: 05/18/2023]
Abstract
Potato virus X (PVX) requires three virally encoded proteins, the triple gene block (TGB), for movement between cells. TGB1 is a multifunctional protein that suppresses host gene silencing and moves from cell to cell through plasmodesmata, while TGB2 and TGB3 are membrane-spanning proteins associated with endoplasmic reticulum-derived granular vesicles. Here, we show that TGB1 organizes the PVX "X-body," a virally induced inclusion structure, by remodeling host actin and endomembranes (endoplasmic reticulum and Golgi). Within the X-body, TGB1 forms helically arranged aggregates surrounded by a reservoir of the recruited host endomembranes. The TGB2/3 proteins reside in granular vesicles within this reservoir, in the same region as nonencapsidated viral RNA, while encapsidated virions accumulate at the outer (cytoplasmic) face of the X-body, which comprises a highly organized virus "factory." TGB1 is both necessary and sufficient to remodel host actin and endomembranes and to recruit TGB2/3 to the X-body, thus emerging as the central orchestrator of the X-body. Our results indicate that the actin/endomembrane-reorganizing properties of TGB1 function to compartmentalize the viral gene products of PVX infection.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | - Karl J. Oparka
- Institute of Molecular Plant Sciences, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom (J.T., O.L., K.B., C.L., K.J.O.); and The James Hutton Institute, Invergowrie, Dundee DD2 5DA, United Kingdom (K.M.W., A.G.R., S.S.C.)
| |
Collapse
|
15
|
Jakubiec A, Yang SW, Chua NH. Arabidopsis DRB4 protein in antiviral defense against Turnip yellow mosaic virus infection. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 69:14-25. [PMID: 21883552 PMCID: PMC3240694 DOI: 10.1111/j.1365-313x.2011.04765.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
RNA silencing is an important antiviral mechanism in diverse eukaryotic organisms. In Arabidopsis DICER-LIKE 4 (DCL4) is the primary antiviral Dicer, required for the production of viral small RNAs from positive-strand RNA viruses. Here, we showed that DCL4 and its interacting partner dsRNA-binding protein 4 (DRB4) participate in the antiviral response to Turnip yellow mosaic virus (TYMV), and that both proteins are required for TYMV-derived small RNA production. In addition, our results indicate that DRB4 has a negative effect on viral coat protein accumulation. Upon infection DRB4 expression was induced and DRB4 protein was recruited from the nucleus to the cytoplasm, where replication and translation of viral RNA occur. DRB4 was associated with viral RNA in vivo and directly interacted in vitro with a TYMV RNA translational enhancer, raising the possibility that DRB4 might repress viral RNA translation. In plants the role of RNA silencing in viral RNA degradation is well established, but its potential function in the regulation of viral protein levels has not yet been explored. We observed that severe infection symptoms are not necessarily correlated with enhanced viral RNA levels, but might be caused by elevated accumulation of viral proteins. Our findings suggest that the control of viral protein as well as RNA levels might be important for mounting an efficient antiviral response.
Collapse
Affiliation(s)
- Anna Jakubiec
- Laboratory of Plant Molecular Biology, The Rockefeller University, New York, NY 10065, USA
| | - Seong Wook Yang
- Department of Plant Biology and Biotechnology, Faculty of Life Science, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Copenhagen, Denmark
| | - Nam-Hai Chua
- Laboratory of Plant Molecular Biology, The Rockefeller University, New York, NY 10065, USA
- To whom correspondence should be addressed. Corresponding author: Nam-Hai Chua , Fax number: 1-212-327-8327, Phone number: 1-212-327-8126
| |
Collapse
|
16
|
Cellular factors in plant virus movement: at the leading edge of macromolecular trafficking in plants. Virology 2011; 411:237-43. [PMID: 21239029 DOI: 10.1016/j.virol.2010.12.021] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Accepted: 12/14/2010] [Indexed: 11/22/2022]
Abstract
To establish systemic infection, plant viruses must be localized to the correct subcellular sites to accomplish replication and then traffic from initially infected cells into neighboring cells and even distant organs. Viruses have evolved various strategies to interact with pre-existing cellular factors to achieve these functions. In this review we discuss plant virus intracellular, intercellular and long-distance movement, focusing on the host cellular factors involved. We emphasize that elucidating viral movement mechanisms will not only shed light on the molecular mechanisms of infection, but will also contribute valuable insights into the regulation of endogenous macromolecular trafficking.
Collapse
|
17
|
Harries PA, Schoelz JE, Nelson RS. Intracellular transport of viruses and their components: utilizing the cytoskeleton and membrane highways. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:1381-93. [PMID: 20653412 DOI: 10.1094/mpmi-05-10-0121] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Plant viruses are obligate organisms that require host components for movement within and between cells. A mechanistic understanding of virus movement will allow the identification of new methods to control virus systemic spread and serve as a model system for understanding host macromolecule intra- and intercellular transport. Recent studies have moved beyond the identification of virus proteins involved in virus movement and their effect on plasmodesmal size exclusion limits to the analysis of their interactions with host components to allow movement within and between cells. It is clear that individual virus proteins and replication complexes associate with and, in some cases, traffic along the host cytoskeleton and membranes. Here, we review these recent findings, highlighting the diverse associations observed between these components and their trafficking capacity. Plant viruses operate individually, sometimes within virus species, to utilize unique interactions between their proteins or complexes and individual host cytoskeletal or membrane elements over time or space for their movement. However, there is not sufficient information for any plant virus to create a complete model of its intracellular movement; thus, more research is needed to achieve that goal.
Collapse
Affiliation(s)
- Phillip A Harries
- Department of Biology, Pittsburg State University, Pittsburg, KS 66762, USA
| | | | | |
Collapse
|
18
|
Hui E, Xiang Y, Rochon D. Distinct regions at the N-terminus of the Cucumber necrosis virus coat protein target chloroplasts and mitochondria. Virus Res 2010; 153:8-19. [PMID: 20600385 DOI: 10.1016/j.virusres.2010.06.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2010] [Revised: 06/08/2010] [Accepted: 06/22/2010] [Indexed: 11/18/2022]
Abstract
Cucumber necrosis virus (CNV) is a spherical virus consisting of 180 identical coat protein (CP) subunits. The N-terminus of the CP subunit contains a 58aa RNA binding (R) domain and a 34aa arm that connects the R domain to the shell. These regions are known to play critical roles in virus assembly and disassembly. It has recently been shown that a region encompassing the arm can function as a chloroplast transit peptide (TP) in infected plants and that targeting may represent a means for virus particle disassembly. In this study, we further delineate the TP region and show that a 22aa sequence at the N-terminus of the shell enhances chloroplast targeting. We also demonstrate that R domain specifically co-localizes with mitochondria in agroinfiltrated plants. Deletion analyses show that the N-terminal 39 amino acids of the R domain are sufficient for mitochondrial targeting and that this region contains features typical of mitochondrial presequences. The R/arm region is found to be dually targeted to mitochondria and chloroplasts suggesting that this region of the CP plays a critical role in determining the fate of CP during the infection process.
Collapse
Affiliation(s)
- Elizabeth Hui
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada
| | | | | |
Collapse
|
19
|
Abstract
Bioimaging contributes significantly to our understanding of plant virus infections. In the present review, we describe technical advances that enable imaging of the infection process at previously unobtainable levels. We highlight how such new advances in subcellular imaging are contributing to a detailed dissection of all stages of the viral infection process. Specifically, we focus on: (i) the increasingly detailed localizations of viral proteins enabled by a diversifying palette of cellular markers; (ii) approaches using fluorescence microscopy for the functional analysis of proteins in vivo; (iii) the imaging of viral RNAs; (iv) methods that bridge the gap between optical and electron microscopy; and (v) methods that are blurring the distinction between imaging and structural biology. We describe the advantages and disadvantages of such techniques and place them in the broader perspective of their utility in analysing plant virus infection.
Collapse
|
20
|
Abstract
This review focuses on the extensive membrane and organelle rearrangements that have been observed in plant cells infected with RNA viruses. The modifications generally involve the formation of spherules, vesicles, and/or multivesicular bodies associated with various organelles such as the endoplasmic reticulum and peroxisomes. These virus-induced organelles house the viral RNA replication complex and are known as virus factories or viroplasms. Membrane and organelle alterations are attributed to the action of one or two viral proteins, which additionally act as a scaffold for the assembly of a large complex of proteins of both viral and host origin and viral RNA. Some virus factories have been shown to align with and traffic along microfilaments. In addition to viral RNA replication, the factories may be involved in other processes such as viral RNA translation and cell-to-cell virus transport. Confining the process of RNA replication to a specific location may also prevent the activation of certain host defense functions.
Collapse
Affiliation(s)
- Jean-François Laliberté
- INRS-Institut Armand-Frappier, Institut National de la Recherche Scientifique, Laval, Québec, Canada H7V 1B7.
| | | |
Collapse
|
21
|
Christensen N, Tilsner J, Bell K, Hammann P, Parton R, Lacomme C, Oparka K. The 5' cap of tobacco mosaic virus (TMV) is required for virion attachment to the actin/endoplasmic reticulum network during early infection. Traffic 2009; 10:536-51. [PMID: 19220815 DOI: 10.1111/j.1600-0854.2009.00889.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Almost nothing is known of the earliest stages of plant virus infections. To address this, we microinjected Cy3 (UTP)-labelled tobacco mosaic virus (TMV) into living tobacco trichome cells. The Cy3-virions were infectious, and the viral genome trafficked from cell to cell. However, neither the fluorescent vRNA pool nor the co-injected green fluorescent protein (GFP) left the injected trichome, indicating that the synthesis of (unlabelled) progeny viral (v)RNA is required to initiate cell-to-cell movement, and that virus movement is not accompanied by passive plasmodesmatal gating. Cy3-vRNA formed granules that became anchored to the motile cortical actin/endoplasmic reticulum (ER) network within minutes of injection. Granule movement on actin/ER was arrested by actin inhibitors indicating actin-dependent RNA movement. The 5' methylguanosine cap was shown to be required for vRNA anchoring to the actin/ER. TMV vRNA lacking the 5' cap failed to form granules and was degraded in the cytoplasm. Removal of the 3' untranslated region or replicase both inhibited replication but did not prevent granule formation and movement. Dual-labelled TMV virions in which the vRNA and the coat protein were highlighted with different fluorophores showed that both fluorescent signals were initially located on the same ER-bound granules, indicating that TMV virions may become attached to the ER prior to uncoating of the viral genome.
Collapse
Affiliation(s)
- Nynne Christensen
- Institute of Molecular Plant Sciences, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JR, UK
| | | | | | | | | | | | | |
Collapse
|
22
|
Tilsner J, Linnik O, Christensen NM, Bell K, Roberts IM, Lacomme C, Oparka KJ. Live-cell imaging of viral RNA genomes using a Pumilio-based reporter. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 57:758-70. [PMID: 18980643 DOI: 10.1111/j.1365-313x.2008.03720.x] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
We describe a method for localizing plant viral RNAs in vivo using Pumilio, an RNA-binding protein, coupled to bimolecular fluorescence complementation (BiFC). Two Pumilio homology domain (PUMHD) polypeptides, fused to either the N- or C-terminal halves of split mCitrine, were engineered to recognize two closely adjacent eight-nucleotide sequences in the genomic RNA of tobacco mosaic virus (TMV). Binding of the PUMHDs to their target sites brought the split mCitrine halves into close proximity, allowing BiFC to occur and revealing the localization of viral RNA within infected cells. The bulk of the RNA was sequestered in characteristic inclusion bodies known as viral replication complexes (VRCs), with a second population of RNA localized in discrete particles distributed throughout the peripheral cytoplasm. Transfer of the TMV Pumilio recognition sequences into the genome of potato virus X (PVX) allowed the PVX RNA to be localized. Unlike TMV, the PVX RNA was concentrated in distinctive 'whorls' within the VRC. Optical sectioning of the PVX VRCs revealed that one of the viral movement proteins was localized to the centres of the RNA whorls, demonstrating significant partitioning of viral RNA and proteins within the VRC. The utility of Pumilio as a fluorescence-based reporter for viral RNA is discussed.
Collapse
Affiliation(s)
- Jens Tilsner
- Institute of Molecular Plant Sciences, University of Edinburgh, Mayfield Road, Edinburgh, EH9 3JR, UK
| | | | | | | | | | | | | |
Collapse
|
23
|
Wei T, Wang A. Biogenesis of cytoplasmic membranous vesicles for plant potyvirus replication occurs at endoplasmic reticulum exit sites in a COPI- and COPII-dependent manner. J Virol 2008; 82:12252-64. [PMID: 18842721 PMCID: PMC2593340 DOI: 10.1128/jvi.01329-08] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2008] [Accepted: 09/29/2008] [Indexed: 12/31/2022] Open
Abstract
Single-stranded positive-sense RNA viruses induce the biogenesis of cytoplasmic membranous vesicles, where viral replication takes place. However, the mechanism underlying this characteristic vesicular proliferation remains poorly understood. Previously, a 6-kDa potyvirus membrane protein (6K) was shown to interact with the endoplasmic reticulum (ER) and to induce the formation of the membranous vesicles. In this study, the involvement of the early secretory pathway in the formation of the 6K-induced vesicles was investigated in planta. By means of live-cell imaging, it was found that the 6K protein was predominantly colocalized with Sar1, Sec23, and Sec24, which are known markers of ER exit sites (ERES). The localization of 6K at ERES was prevented by the coexpression of a dominant-negative mutant of Sar1 that disables the COPII activity or by the coexpression of a mutant of Arf1 that disrupts the COPI complex. The secretion of a soluble secretory marker targeting the apoplast was arrested at the level of the ER in cells overexpressing 6K or infected by a potyvirus. This blockage of protein trafficking out of the ER by 6K and the distribution of 6K toward the ERES may account for the aggregation of the 6K-bound vesicles. Finally, virus infection was reduced when the accumulation of 6K at ERES was inhibited by impairing either the COPI or COPII complex. Taken together, these results imply that the cellular COPI and COPII coating machineries are involved in the biogenesis of the potyvirus 6K vesicles at the ERES for viral-genome replication.
Collapse
Affiliation(s)
- Taiyun Wei
- Southern Crop Protection and Food Research Centre, AAFC, 1391 Sandford Street, London, Ontario N5V 4T3, Canada
| | | |
Collapse
|
24
|
Altered gene expression changes in Arabidopsis leaf tissues and protoplasts in response to Plum pox virus infection. BMC Genomics 2008; 9:325. [PMID: 18613973 PMCID: PMC2478689 DOI: 10.1186/1471-2164-9-325] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2007] [Accepted: 07/09/2008] [Indexed: 11/10/2022] Open
Abstract
Background Virus infection induces the activation and suppression of global gene expression in the host. Profiling gene expression changes in the host may provide insights into the molecular mechanisms that underlie host physiological and phenotypic responses to virus infection. In this study, the Arabidopsis Affymetrix ATH1 array was used to assess global gene expression changes in Arabidopsis thaliana plants infected with Plum pox virus (PPV). To identify early genes in response to PPV infection, an Arabidopsis synchronized single-cell transformation system was developed. Arabidopsis protoplasts were transfected with a PPV infectious clone and global gene expression changes in the transfected protoplasts were profiled. Results Microarray analysis of PPV-infected Arabidopsis leaf tissues identified 2013 and 1457 genes that were significantly (Q ≤ 0.05) up- (≥ 2.5 fold) and downregulated (≤ -2.5 fold), respectively. Genes associated with soluble sugar, starch and amino acid, intracellular membrane/membrane-bound organelles, chloroplast, and protein fate were upregulated, while genes related to development/storage proteins, protein synthesis and translation, and cell wall-associated components were downregulated. These gene expression changes were associated with PPV infection and symptom development. Further transcriptional profiling of protoplasts transfected with a PPV infectious clone revealed the upregulation of defence and cellular signalling genes as early as 6 hours post transfection. A cross sequence comparison analysis of genes differentially regulated by PPV-infected Arabidopsis leaves against uniEST sequences derived from PPV-infected leaves of Prunus persica, a natural host of PPV, identified orthologs related to defence, metabolism and protein synthesis. The cross comparison of genes differentially regulated by PPV infection and by the infections of other positive sense RNA viruses revealed a common set of 416 genes. These identified genes, particularly the early responsive genes, may be critical in virus infection. Conclusion Gene expression changes in PPV-infected Arabidopsis are the molecular basis of stress and defence-like responses, PPV pathogenesis and symptom development. The differentially regulated genes, particularly the early responsive genes, and a common set of genes regulated by infections of PPV and other positive sense RNA viruses identified in this study are candidates suitable for further functional characterization to shed lights on molecular virus-host interactions.
Collapse
|
25
|
Abstract
The genomes of positive-strand RNA viruses undergo conformational shifts that complicate efforts to equate structures with function. We have initiated a detailed analysis of secondary and tertiary elements within the 3' end of Turnip crinkle virus (TCV) that are required for viral accumulation in vivo. MPGAfold, a massively parallel genetic algorithm, suggested the presence of five hairpins (H4a, H4b, and previously identified hairpins H4, H5, and Pr) and one H-type pseudoknot (Psi(3)) within the 3'-terminal 194 nucleotides (nt). In vivo compensatory mutagenesis analyses confirmed the existence of H4a, H4b, Psi(3) and a second pseudoknot (Psi(2)) previously identified in a TCV satellite RNA. In-line structure probing of the 194-nt fragment supported the coexistence of H4, H4a, H4b, Psi(3) and a pseudoknot that connects H5 and the 3' end (Psi(1)). Stepwise replacements of TCV elements with the comparable elements from Cardamine chlorotic fleck virus indicated that the complete 142-nt 3' end, and subsets containing Psi(3), H4a, and H4b or Psi(3), H4a, H4b, H5, and Psi(2), form functional domains for virus accumulation in vivo. A new 3-D molecular modeling protocol (RNA2D3D) predicted that H4a, H4b, H5, Psi(3), and Psi(2) are capable of simultaneous existence and bears some resemblance to a tRNA. The related Japanese iris necrotic ring virus does not have comparable domains. These results provide a framework for determining how interconnected elements participate in processes that require 3' untranslated region sequences such as translation and replication.
Collapse
|
26
|
Sanfaçon H, Zhang G. Analysis of interactions between viral replicase proteins and plant intracellular membranes. Methods Mol Biol 2008; 451:361-375. [PMID: 18370268 DOI: 10.1007/978-1-59745-102-4_25] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Replication of the genome of positive-strand RNA plant viruses takes place in membrane-bound complexes that contain viral replicase proteins, viral RNA, and host proteins. Many viral replicase proteins play a crucial role in the assembly of replication complexes at intracellular membranes. They are integral membrane proteins that interact directly with the membranes and bring other proteins and the viral RNA to the complex via protein-protein or protein-RNA interactions. In this chapter, we describe subcellular fractionation methods that determine whether viral proteins are integral membrane proteins in planta. Differential centrifugation techniques are used to produce membrane-enriched fractions, which can then be analyzed for the presence of viral replicase proteins by immunoblotting. Confirmation of the membrane-association is obtained by membrane flotation assays and treatment of membrane-enriched fractions with high salt or high pH followed by detection of the viral proteins. Because many plant viruses replicate in association with the endoplasmic reticulum (ER), we also discuss two techniques to specifically analyze the interaction of viral proteins with these membranes. These techniques are continuous sucrose-gradient fractionation in the presence or absence of 3 mM Mg2+ and glycosylation assays.
Collapse
Affiliation(s)
- Hélène Sanfaçon
- Pacific Agri-Food Research Centre, 5000, 4200 Highway 97, Summerland, BC, V0H 1Z0, Canada
| | | |
Collapse
|
27
|
Chisholm J, Zhang G, Wang A, Sanfaçon H. Peripheral association of a polyprotein precursor form of the RNA-dependent RNA polymerase of Tomato ringspot virus with the membrane-bound viral replication complex. Virology 2007; 368:133-44. [PMID: 17658576 DOI: 10.1016/j.virol.2007.06.032] [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: 05/04/2007] [Revised: 06/13/2007] [Accepted: 06/29/2007] [Indexed: 11/23/2022]
Abstract
Replication of Tomato ringspot virus (ToRSV) occurs in association with endoplasmic reticulum (ER)-derived membranes. We have previously shown that the putative nucleotide triphosphate-binding protein (NTB) of ToRSV is an ER-targeted protein and that an intermediate polyprotein containing the domains for NTB and for the genome-linked viral protein (VPg) is associated with the replication complex. We now report the detection of a 95-kDa polyprotein that contains the domains for the RNA-dependent RNA polymerase (Pol), the proteinase (Pro) and the VPg. This polyprotein appears to be a truncated version of the full-length 111-kDa VPg-Pro-Pol polyprotein and was termed VPg-Pro-Pol'. A subpopulation of VPg-Pro-Pol' was peripherally associated with ER-derived membranes active in viral replication. However, the VPg, Pro and Pol domains did not target to membranes in the absence of viral infection. We propose a model in which VPg-Pro-Pol' is brought to the site of replication through interaction with a viral membrane protein.
Collapse
Affiliation(s)
- Joan Chisholm
- Pacific Agri-Food Research Centre, Agriculture and Agri-Food Canada, P.O. Box 5000, 4200 Highway 97, Summerland, B.C., Canada V0H 1Z0
| | | | | | | |
Collapse
|
28
|
Jakubiec A, Jupin I. Regulation of positive-strand RNA virus replication: the emerging role of phosphorylation. Virus Res 2007; 129:73-9. [PMID: 17764774 PMCID: PMC7132427 DOI: 10.1016/j.virusres.2007.07.012] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2007] [Revised: 07/20/2007] [Accepted: 07/20/2007] [Indexed: 12/29/2022]
Abstract
Protein phosphorylation is a reversible post-translational modification that plays a fundamental role in the regulation of many cellular processes. Phosphorylation can modulate protein properties such as enzymatic activity, stability, subcellular localization or interaction with binding partners. The importance of phosphorylation of the replication proteins of negative-strand RNA viruses has previously been documented but recent evidence suggests that replication of positive-strand RNA viruses – the largest class of viruses, including significant human, animal and plant pathogens – may also be regulated by phosphorylation events. The objective of this review is to summarize current knowledge regarding the various regulatory roles played by phosphorylation of nonstructural viral proteins in the replication of positive-strand RNA viruses.
Collapse
Affiliation(s)
| | - Isabelle Jupin
- Corresponding author. Tel.: +33 1 44 27 40 99; fax: +33 1 44 27 57 16.
| |
Collapse
|
29
|
Zhang G, Sanfaçon H. Characterization of membrane association domains within the Tomato ringspot nepovirus X2 protein, an endoplasmic reticulum-targeted polytopic membrane protein. J Virol 2006; 80:10847-57. [PMID: 16928745 PMCID: PMC1641798 DOI: 10.1128/jvi.00789-06] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2006] [Accepted: 08/09/2006] [Indexed: 12/19/2022] Open
Abstract
Replication of nepoviruses (family Comoviridae) occurs in association with endoplasmic reticulum (ER)-derived membranes. We have previously shown that the putative nucleoside triphosphate-binding protein (NTB) of Tomato ringspot nepovirus is an integral membrane protein with two ER-targeting sequences and have suggested that it anchors the viral replication complex (VRC) to the membranes. A second highly hydrophobic protein domain (X2) is located immediately upstream of the NTB domain in the RNA1-encoded polyprotein. X2 shares conserved sequence motifs with the comovirus 32-kDa protein, an ER-targeted protein implicated in VRC assembly. In this study, we examined the ability of X2 to associate with intracellular membranes. The X2 protein was fused to the green fluorescent protein and expressed in Nicotiana benthamiana by agroinfiltration. Confocal microscopy and membrane flotation experiments suggested that X2 is targeted to ER membranes. Mutagenesis studies revealed that X2 contains multiple ER-targeting domains, including two C-terminal transmembrane helices and a less-well-defined domain further upstream. To investigate the topology of the protein in the membrane, in vitro glycosylation assays were conducted using X2 derivatives that contained N-glycosylation sites introduced at the N or C termini of the protein. The results led us to propose a topological model for X2 in which the protein traverses the membrane three times, with the N terminus oriented in the lumen and the C terminus exposed to the cytoplasmic face. Taken together, our results indicate that X2 is an ER-targeted polytopic membrane protein and raises the possibility that it acts as a second membrane anchor for the VRC.
Collapse
Affiliation(s)
- Guangzhi Zhang
- Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | | |
Collapse
|