1
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Furukawa H, Nakamura S, Mizuta R, Sakamoto K, Inaba H, Sawada SI, Sasaki Y, Akiyoshi K, Matsuura K. Enveloped Viral Replica Equipped with Spike Protein Derived from SARS-CoV-2. ACS Synth Biol 2024. [PMID: 38885191 DOI: 10.1021/acssynbio.4c00165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/20/2024]
Abstract
Synthetic viral nanostructures are useful as materials for analyzing the biological behavior of natural viruses and as vaccine materials. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an enveloped virus embedding a spike (S) protein involved in host cell infection. Although nanomaterials modified with an S protein without an envelope membrane have been developed, they are considered unsuitable for stability and functionality. We previously constructed an enveloped viral replica complexed with a cationic lipid bilayer and an anionic artificial viral capsid self-assembled from β-annulus peptides. In this study, we report the first example of an enveloped viral replica equipped with an S protein derived from SARS-CoV-2. Interestingly, even the S protein equipped on the enveloped viral replica bound strongly to the free angiotensin-converting enzyme 2 (ACE2) receptor as well as ACE2 localized on the cell membrane.
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Affiliation(s)
- Hiroto Furukawa
- Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, Tottori 680-8552, Japan
| | - Sosuke Nakamura
- Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, Tottori 680-8552, Japan
| | - Ryosuke Mizuta
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Kentarou Sakamoto
- Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, Tottori 680-8552, Japan
| | - Hiroshi Inaba
- Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, Tottori 680-8552, Japan
- Centre for Research on Green Sustainable Chemistry, Tottori University, Tottori 680-8552, Japan
| | - Shin-Ichi Sawada
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
- Synergy Institute for Futuristic Mucosal Vaccine Research and Development, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan
| | - Yoshihiro Sasaki
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Kazunari Akiyoshi
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
- Department of Immunology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Kazunori Matsuura
- Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, Tottori 680-8552, Japan
- Centre for Research on Green Sustainable Chemistry, Tottori University, Tottori 680-8552, Japan
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2
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DeMell A, Mendoza MR, Scholthof HB. A tomato bushy stunt virus-based vector for simultaneous editing and sensing to survey the host antiviral RNA silencing machinery. PNAS NEXUS 2024; 3:pgad436. [PMID: 38264147 PMCID: PMC10805433 DOI: 10.1093/pnasnexus/pgad436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 12/06/2023] [Indexed: 01/25/2024]
Abstract
A tomato bushy stunt virus (TBSV)-derived vector system was applied for the delivery of CRISPR/Cas9 gene editing materials, to facilitate rapid, transient assays of host-virus interactions involved in the RNA silencing pathway. Toward this, single guide RNAs designed to target key components of the virus-induced host RNA silencing pathway (AGO2, DCL2, HEN1) were inserted into TBSV-based GFP-expressing viral vectors TBSV-GFP (TG) and its P19 defective mutant TGΔP19. This produced rapid, efficient, and specific gene editing in planta. Targeting AGO2, DCL2, or HEN1 partially rescued the lack of GFP accumulation otherwise associated with TGΔP19. Since the rescue phenotypes are normally only observed in the presence of the P19 silencing suppressor, the results support that the DCL2, HEN1, and AGO2 proteins are involved in anti-TBSV RNA silencing. Additionally, we show that knockdown of the RNA silencing machinery increases cargo expression from a nonviral binary Cas9 vector. The TBSV-based gene editing technology described in this study can be adapted for transient heterologous expression, rapid gene function screens, and molecular interaction studies in many plant species considering the wide host range of TBSV. In summary, we demonstrate that a plant virus can be used to establish gene editing while simultaneously serving as an accumulation sensor for successful targeting of its homologous antiviral silencing machinery components.
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Affiliation(s)
- April DeMell
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843, USA
- Present address: Plant Biology, UC Davis, Davis, CA, USA
| | - Maria R Mendoza
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843, USA
- Present address: Fujifilm Diosynth Biotechnologies Texas, College Station, TX, USA
| | - Herman B Scholthof
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843, USA
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3
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Gruber C, Gursinsky T, Gago-Zachert S, Pantaleo V, Behrens SE. Effective Antiviral Application of Antisense in Plants by Exploiting Accessible Sites in the Target RNA. Int J Mol Sci 2023; 24:17153. [PMID: 38138982 PMCID: PMC10743417 DOI: 10.3390/ijms242417153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 12/01/2023] [Accepted: 12/03/2023] [Indexed: 12/24/2023] Open
Abstract
Antisense oligodeoxynucleotides (ASOs) have long been used to selectively inhibit or modulate gene expression at the RNA level, and some ASOs are approved for clinical use. However, the practicability of antisense technologies remains limited by the difficulty of reliably predicting the sites accessible to ASOs in complex folded RNAs. Recently, we applied a plant-based method that reproduces RNA-induced RNA silencing in vitro to reliably identify sites in target RNAs that are accessible to small interfering RNA (siRNA)-guided Argonaute endonucleases. Here, we show that this method is also suitable for identifying ASOs that are effective in DNA-induced RNA silencing by RNases H. We show that ASOs identified in this way that target a viral genome are comparably effective in protecting plants from infection as siRNAs with the corresponding sequence. The antiviral activity of the ASOs could be further enhanced by chemical modification. This led to two important conclusions: siRNAs and ASOs that can effectively knock down complex RNA molecules can be identified using the same approach, and ASOs optimized in this way could find application in crop protection. The technology developed here could be useful not only for effective RNA silencing in plants but also in other organisms.
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Affiliation(s)
- Cornelia Gruber
- Institute of Biochemistry and Biotechnology, Section Microbial Biotechnology, Martin Luther University Halle-Wittenberg, D-06120 Halle (Saale), Germany; (C.G.); (T.G.); (S.G.-Z.)
| | - Torsten Gursinsky
- Institute of Biochemistry and Biotechnology, Section Microbial Biotechnology, Martin Luther University Halle-Wittenberg, D-06120 Halle (Saale), Germany; (C.G.); (T.G.); (S.G.-Z.)
| | - Selma Gago-Zachert
- Institute of Biochemistry and Biotechnology, Section Microbial Biotechnology, Martin Luther University Halle-Wittenberg, D-06120 Halle (Saale), Germany; (C.G.); (T.G.); (S.G.-Z.)
| | - Vitantonio Pantaleo
- Institute for Sustainable Plant Protection, Department of Biology, Agricultural and Food Sciences National Research Council, Bari Unit, I-70126 Bari, Italy;
| | - Sven-Erik Behrens
- Institute of Biochemistry and Biotechnology, Section Microbial Biotechnology, Martin Luther University Halle-Wittenberg, D-06120 Halle (Saale), Germany; (C.G.); (T.G.); (S.G.-Z.)
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4
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Scholthof HB, Scholthof KBG. Plant virology: an RNA treasure trove. TRENDS IN PLANT SCIENCE 2023; 28:1277-1289. [PMID: 37495453 DOI: 10.1016/j.tplants.2023.06.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 06/12/2023] [Accepted: 06/27/2023] [Indexed: 07/28/2023]
Abstract
Key principles pertaining to RNA biology not infrequently have their origins in plant virology. Examples have arisen from studies on viral RNA-intrinsic properties and the infection process from gene expression, replication, movement, and defense evasion to biotechnological applications. Since RNA is at the core of the central dogma in molecular biology, how plant virology assisted in the reinforcement or adaptations of this concept, while at other instances shook up elements of the doctrine, is discussed. Moreover, despite the negative effects of viral diseases in agriculture worldwide, plant viruses can be considered a scientific treasure trove. Today they remain tools of discovery for biotechnology, studying evolution, cell biology, and host-microbe interactions.
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Affiliation(s)
- Herman B Scholthof
- Department of Plant Pathology & Microbiology, Texas A&M University, College Station TX 77843, USA.
| | - Karen-Beth G Scholthof
- Department of Plant Pathology & Microbiology, Texas A&M University, College Station TX 77843, USA
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5
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Altabella T, Ramirez-Estrada K, Ferrer A. Phytosterol metabolism in plant positive-strand RNA virus replication. PLANT CELL REPORTS 2022; 41:281-291. [PMID: 34665312 DOI: 10.1007/s00299-021-02799-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Accepted: 09/25/2021] [Indexed: 06/13/2023]
Abstract
The genome of most plant viruses consists of a single positive-strand of RNA (+ ssRNA). Successful replication of these viruses is fully dependent on the endomembrane system of the infected cells, which experiences a massive proliferation and a profound reshaping that enables assembly of the macromolecular complexes where virus genome replication occurs. Assembly of these viral replicase complexes (VRCs) requires a highly orchestrated interplay of multiple virus and co-opted host cell factors to create an optimal microenvironment for efficient assembly and functioning of the virus genome replication machinery. It is now widely accepted that VRC formation involves the recruitment of high levels of sterols, but the specific role of these essential components of cell membranes and the precise molecular mechanisms underlying sterol enrichment at VRCs are still poorly known. In this review, we intend to summarize the most relevant knowledge on the role of sterols in ( +)ssRNA virus replication and discuss the potential of manipulating the plant sterol pathway to help plants fight these infectious agents.
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Affiliation(s)
- Teresa Altabella
- Plant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Cerdanyola, 08193, Barcelona, Spain.
- Department of Biology, Healthcare and the Environment, Faculty of Pharmacy and Food Sciences, University of Barcelona, 08028, Barcelona, Spain.
| | - Karla Ramirez-Estrada
- Laboratory of Cell Metabolism, Faculty of Chemistry, Autonomous University of Nuevo León, San Nicolás de los Garza, NL, 66451, México
| | - Albert Ferrer
- Plant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Cerdanyola, 08193, Barcelona, Spain.
- Department of Biochemistry and Physiology, Faculty of Pharmacy and Food Sciences, University of Barcelona, 08028, Barcelona, Spain.
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6
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Nkanga CI, Steinmetz NF. The pharmacology of plant virus nanoparticles. Virology 2021; 556:39-61. [PMID: 33545555 PMCID: PMC7974633 DOI: 10.1016/j.virol.2021.01.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 01/20/2021] [Accepted: 01/21/2021] [Indexed: 12/14/2022]
Abstract
The application of nanoparticles for medical purposes has made enormous strides in providing new solutions to health problems. The observation that plant virus-based nanoparticles (VNPs) can be repurposed and engineered as smart bio-vehicles for targeted drug delivery and imaging has launched extensive research for improving the therapeutic and diagnostic management of various diseases. There is evidence that VNPs are promising high value nanocarriers with potential for translational development. This is mainly due to their unique features, encompassing structural uniformity, ease of manufacture and functionalization by means of expression, chemical biology and self-assembly. While the development pipeline is moving rapidly, with many reports focusing on engineering and manufacturing aspects to tailor the properties and efficacy of VNPs, fewer studies have focused on gaining insights into the nanotoxicity of this novel platform nanotechnology. Herein, we discuss the pharmacology of VNPs as a function of formulation and route of administration. VNPs are reviewed in the context of their application as therapeutic adjuvants or nanocarrier excipients to initiate, enhance, attenuate or impede the formulation's toxicity. The summary of the data however also underlines the need for meticulous VNP structure-nanotoxicity studies to improve our understanding of their in vivo fates and pharmacological profiles to pave the way for translation of VNP-based formulations into the clinical setting.
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Affiliation(s)
| | - Nicole F Steinmetz
- Department of NanoEngineering, University of California-San Diego, La Jolla, CA, 92039, United States; Department of Bioengineering, Department of Radiology, Center for NanoImmunoEngineering, Moores Cancer Center, Institute for Materials Discovery and Design, University of California-San Diego, La Jolla, CA, 92039, United States.
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7
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Xu L, Li Z, Wang S. Development of a Virus-Based Reporter System for Functional Analysis of Plant rRNA Gene Promoter. Front Microbiol 2021; 12:637347. [PMID: 33679673 PMCID: PMC7928365 DOI: 10.3389/fmicb.2021.637347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 01/25/2021] [Indexed: 11/27/2022] Open
Abstract
Reporter gene-based expression systems have been intensively used in plants for monitoring the activity of gene promoters. However, rRNA transcripts are unable to efficiently express a reporter gene due to a lack of a 5' cap. Because of this obstacle, plant rRNA gene promoters are less well characterized to this day. We developed a virus-based reporter system to characterize the Nicotiana benthamiana rRNA (NbrRNA) gene promoter. The system utilizes the cap-independent translation strategy of viral genomic mRNA and uses the virus-expressed green fluorescent protein (GFP) as an indicator of the rRNA gene promoter activity in virus-infected plants. Based on the reporter system, some characteristics of the N. benthamiana rRNA gene promoter were revealed. The results showed that the strength of the NbrRNA gene promoter was lower than that of the cauliflower mosaic virus (CaMV) 35S promoter, a well-characterized polymerase II promoter. The sequences between −77 and +42 are sufficient for the NbrRNA gene promoter-mediated transcription and the NbrRNA gene promoter may lack the functional upstream control element (UCE). Interestingly, NbrRNA gene promoter activity was increased when the 35S enhancer was introduced. An intron-excision mediated assay revealed that the NbrRNA gene promoter can be inefficiently used by RNA polymerase II in N. benthamiana cells. This virus-based reporter system is easier to operate and more convenient when compared with the previously Pol I promoter assays. And it offers a promising solution to analyzing the functional architecture of plant rRNA gene promoter.
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Affiliation(s)
- Li Xu
- Key Laboratory of Ministry of Education for Protection and Utilization of Special Biological Resources in Western China, School of Life Science, Ningxia University, Yinchuan, China
| | - Zhiying Li
- Key Laboratory of Ministry of Education for Protection and Utilization of Special Biological Resources in Western China, School of Life Science, Ningxia University, Yinchuan, China.,Key Laboratory of Modern Molecular Breeding for Dominant and Special Crops in Ningxia, School of Life Science, Ningxia University, Yinchuan, China
| | - Sheng Wang
- Key Laboratory of Ministry of Education for Protection and Utilization of Special Biological Resources in Western China, School of Life Science, Ningxia University, Yinchuan, China.,Key Laboratory of Modern Molecular Breeding for Dominant and Special Crops in Ningxia, School of Life Science, Ningxia University, Yinchuan, China
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8
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Zhang X, Ding X, Li Z, Wang S. Development of Tomato bushy stunt virus-based vectors for fusion and non-fusion expression of heterologous proteins in an alternative host Nicotiana excelsiana. Appl Microbiol Biotechnol 2020; 104:8413-8425. [PMID: 32830290 DOI: 10.1007/s00253-020-10837-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 07/22/2020] [Accepted: 08/14/2020] [Indexed: 01/06/2023]
Abstract
Plant virus-based expression systems are an alternative expression platform for the production of clinically and industrially useful recombinant proteins. Nonetheless, due to a lack of viral vector with the commercial potentials, it is urgent to design and develop new, versatile, and efficient plant virus vectors. The genome of Tomato bushy stunt virus (TBSV) offers an attractive alternative to being modified as a vector for producing heterologous proteins in plants. Here, we developed a set of novel fusion and non-fusion TBSV-CP replacement vectors, which provide more flexible and efficient tools for expressing proteins of interest in plants. An alternative tobacco plant, Nicotiana excelsiana, was used in this study as a host for newly constructed TBSV vectors because the unwanted necrotic effects were reported on the commonly used Nicotiana benthamiana host associated with expression of TBSV-encoded P19 protein. The data showed that TBSV vectors caused a symptomless infection and overexpressed reporter gene in N. excelsiana leaves, demonstrating that N. excelsiana is an ideal host plant for TBSV-mediated heterologous gene expression. Moreover, a TBSV non-fusion vector, dAUG, shows the similar accumulation level of reporter proteins to that of TMV- and PVX-based vectors in side-by-side comparison and provides more flexible aspects than the previously developed TBSV vectors. Collectively, our newly developed TBSV expression system adds a new member to the family of plant viral expression vectors and meanwhile offers a flexible and highly effective approach for producing proteins of interest in plants. KEY POINTS: • The TBSV-based transient expression system has been significantly improved. • The necrotic effects caused by viral P19 protein were avoided by the usage of N. excelsiana as a host plant. • The expression level of the non-fusion vector was similar to the most effective virus vectors reported so far.
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Affiliation(s)
- Xiqian Zhang
- Key Laboratory of Ministry of Education for Protection and Utilization of Special Biological Resources in Western China, Yinchuan, 750021, China
| | - Xiangzhen Ding
- Key Laboratory of Ministry of Education for Protection and Utilization of Special Biological Resources in Western China, Yinchuan, 750021, China
- School of Life Science, Ningxia University, 539 W Helanshan Road, Yinchuan, 750021, China
| | - Zhiying Li
- Key Laboratory of Ministry of Education for Protection and Utilization of Special Biological Resources in Western China, Yinchuan, 750021, China
- School of Life Science, Ningxia University, 539 W Helanshan Road, Yinchuan, 750021, China
| | - Sheng Wang
- Key Laboratory of Ministry of Education for Protection and Utilization of Special Biological Resources in Western China, Yinchuan, 750021, China.
- School of Life Science, Ningxia University, 539 W Helanshan Road, Yinchuan, 750021, China.
- Key Laboratory of Modern Molecular Breeding for Dominant and Special Crops in Ningxia, Yinchuan, 750021, China.
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9
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Gago-Zachert S, Schuck J, Weinholdt C, Knoblich M, Pantaleo V, Grosse I, Gursinsky T, Behrens SE. Highly efficacious antiviral protection of plants by small interfering RNAs identified in vitro. Nucleic Acids Res 2019; 47:9343-9357. [PMID: 31433052 PMCID: PMC6755098 DOI: 10.1093/nar/gkz678] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 06/21/2019] [Accepted: 08/02/2019] [Indexed: 01/09/2023] Open
Abstract
In response to a viral infection, the plant’s RNA silencing machinery processes viral RNAs into a huge number of small interfering RNAs (siRNAs). However, a very few of these siRNAs actually interfere with viral replication. A reliable approach to identify these immunologically effective siRNAs (esiRNAs) and to define the characteristics underlying their activity has not been available so far. Here, we develop a novel screening approach that enables a rapid functional identification of antiviral esiRNAs. Tests on the efficacy of such identified esiRNAs of a model virus achieved a virtual full protection of plants against a massive subsequent infection in transient applications. We find that the functionality of esiRNAs depends crucially on two properties: the binding affinity to Argonaute proteins and the ability to access the target RNA. The ability to rapidly identify functional esiRNAs could be of great benefit for all RNA silencing-based plant protection measures against viruses and other pathogens.
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Affiliation(s)
- Selma Gago-Zachert
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Halle/Saale D-06120, Germany.,Department of Molecular Signal Processing, Leibniz Institute of Plant Biochemistry, Halle/Saale D-06120, Germany
| | - Jana Schuck
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Halle/Saale D-06120, Germany
| | - Claus Weinholdt
- Institute of Computer Science, Martin Luther University Halle-Wittenberg, Halle/Saale D-06120, Germany
| | - Marie Knoblich
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Halle/Saale D-06120, Germany
| | - Vitantonio Pantaleo
- Institute for Sustainable Plant Protection-Consiglio Nazionale delle Ricerche, Research Unit of Bari, Bari I-70126, Italy
| | - Ivo Grosse
- Institute of Computer Science, Martin Luther University Halle-Wittenberg, Halle/Saale D-06120, Germany.,German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig D-04103, Germany
| | - Torsten Gursinsky
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Halle/Saale D-06120, Germany
| | - Sven-Erik Behrens
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Halle/Saale D-06120, Germany
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10
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Mendoza MR, Payne AN, Castillo S, Crocker M, Shaw BD, Scholthof HB. Expression of Separate Proteins in the Same Plant Leaves and Cells Using Two Independent Virus-Based Gene Vectors. FRONTIERS IN PLANT SCIENCE 2017; 8:1808. [PMID: 29163561 PMCID: PMC5681929 DOI: 10.3389/fpls.2017.01808] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 10/05/2017] [Indexed: 05/27/2023]
Abstract
Plant viral vectors enable the expression of proteins at high levels in a relatively short time. For many purposes (e.g., cell biological interaction studies) it may be desirable to express more than one protein in a single cell but that is often not feasible when using a single virus vector. Such a co-expression strategy requires the simultaneous delivery by two compatible and non-competitive viruses that can co-exist to each express a separate protein. Here, we report on the use of two agro-launchable coat-protein gene substitution GFP-expressing virus vector systems based on Tomato bushy stunt virus (TBSV) referred to as TG, and Tobacco mosaic virus (TMV) annotated as TRBO-G. TG expressed GFP in Nicotiana benthamiana, tomato, lettuce and cowpea, whereas expression from TRBO-G was detected only in the first two species. Upon co-infiltration of the two vectors co-expression was monitored by: molecular detection of the two slightly differently sized GFPs, suppressor-complementation assays, and using TG in combination with TRBO-RFP. All the results revealed that in N. benthamiana and tomato the TBSV and TMV vectors accumulated and expressed proteins in the same plants, the same leaves, and in the same cells. Therefore, co-expression by these two vectors provides a platform for fast and high level expression of proteins to study their cell biology or other properties.
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11
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Zhao RY. Yeast for virus research. MICROBIAL CELL (GRAZ, AUSTRIA) 2017; 4:311-330. [PMID: 29082230 PMCID: PMC5657823 DOI: 10.15698/mic2017.10.592] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 08/27/2017] [Indexed: 12/25/2022]
Abstract
Budding yeast (Saccharomyces cerevisiae) and fission yeast (Schizosaccharomyces pombe) are two popular model organisms for virus research. They are natural hosts for viruses as they carry their own indigenous viruses. Both yeasts have been used for studies of plant, animal and human viruses. Many positive sense (+) RNA viruses and some DNA viruses replicate with various levels in yeasts, thus allowing study of those viral activities during viral life cycle. Yeasts are single cell eukaryotic organisms. Hence, many of the fundamental cellular functions such as cell cycle regulation or programed cell death are highly conserved from yeasts to higher eukaryotes. Therefore, they are particularly suited to study the impact of those viral activities on related cellular activities during virus-host interactions. Yeasts present many unique advantages in virus research over high eukaryotes. Yeast cells are easy to maintain in the laboratory with relative short doubling time. They are non-biohazardous, genetically amendable with small genomes that permit genome-wide analysis of virologic and cellular functions. In this review, similarities and differences of these two yeasts are described. Studies of virologic activities such as viral translation, viral replication and genome-wide study of virus-cell interactions in yeasts are highlighted. Impacts of viral proteins on basic cellular functions such as cell cycle regulation and programed cell death are discussed. Potential applications of using yeasts as hosts to carry out functional analysis of small viral genome and to develop high throughput drug screening platform for the discovery of antiviral drugs are presented.
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Affiliation(s)
- Richard Yuqi Zhao
- Department of Pathology, Department of Microbiology and Immunology, Institute of Global Health, and Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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12
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Characterization and complete genome sequence of a panicovirus from Bermuda grass by high-throughput sequencing. Arch Virol 2016; 162:1099-1102. [DOI: 10.1007/s00705-016-3165-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 10/22/2016] [Indexed: 10/20/2022]
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13
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Omarov RT, Ciomperlik J, Scholthof HB. An in vitro reprogrammable antiviral RISC with size-preferential ribonuclease activity. Virology 2016; 490:41-8. [PMID: 26812224 DOI: 10.1016/j.virol.2015.12.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 12/22/2015] [Accepted: 12/23/2015] [Indexed: 01/29/2023]
Abstract
Infection of Nicotiana benthamiana plants with Tomato bushy stunt virus (TBSV) mutants compromised for silencing suppression induces formation of an antiviral RISC (vRISC) that can be isolated using chromatography procedures. The isolated vRISC sequence-specifically degrades TBSV RNA in vitro, its activity can be down-regulated by removing siRNAs, and re-stimulated by exogenous supply of siRNAs. vRISC is most effective at hydrolyzing the ~4.8kb genomic RNA, but less so for a ~2.2kb TBSV subgenomic mRNA (sgRNA1), while the 3' co-terminal sgRNA2 of ~0.9kb appears insensitive to vRISC cleavage. Moreover, experiments with in vitro generated 5' co-terminal viral transcripts show that RNAs of ~2.7kb are efficiently cleaved while those of ~1.1kb or shorter are unaffected. The isolated antiviral ribonuclease complex fails to degrade ~0.4kb defective interfering RNAs (DIs) in vitro, agreeing with findings that in plants DIs are not targeted by silencing.
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Affiliation(s)
- Rustem T Omarov
- Department of Plant Pathology and Microbiology, Texas A&M University, 2132 TAMU, College Station, TX 77843, United States
| | - Jessica Ciomperlik
- Department of Plant Pathology and Microbiology, Texas A&M University, 2132 TAMU, College Station, TX 77843, United States
| | - Herman B Scholthof
- Department of Plant Pathology and Microbiology, Texas A&M University, 2132 TAMU, College Station, TX 77843, United States.
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14
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Ruščić J, Gutiérrez-Aguirre I, Tušek Žnidarič M, Kolundžija S, Slana A, Barut M, Ravnikar M, Krajačić M. A new application of monolithic supports: The separation of viruses from one another. J Chromatogr A 2015; 1388:69-78. [DOI: 10.1016/j.chroma.2015.01.097] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 01/30/2015] [Accepted: 01/30/2015] [Indexed: 11/29/2022]
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15
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Shamekova M, Mendoza MR, Hsieh YC, Lindbo J, Omarov RT, Scholthof HB. Tombusvirus-based vector systems to permit over-expression of genes or that serve as sensors of antiviral RNA silencing in plants. Virology 2014; 452-453:159-65. [PMID: 24606693 DOI: 10.1016/j.virol.2013.12.031] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 10/19/2013] [Accepted: 12/23/2013] [Indexed: 01/16/2023]
Abstract
A next generation Tomato bushy stunt virus (TBSV) coat protein gene replacement vector system is described that can be applied by either RNA inoculation or through agroinfiltration. A vector expressing GFP rapidly yields high levels of transient gene expression in inoculated leaves of various plant species, as illustrated for Nicotiana benthamiana, cowpea, tomato, pepper, and lettuce. A start-codon mutation to down-regulate the dose of the P19 silencing suppressor reduces GFP accumulation, whereas mutations that result in undetectable levels of P19 trigger rapid silencing of GFP. Compared to existing virus vectors the TBSV system has a unique combination of a very broad host range, rapid and high levels of replication and gene expression, and the ability to regulate its suppressor. These features are attractive for quick transient assays in numerous plant species for over-expression of genes of interest, or as a sensor to monitor the efficacy of antiviral RNA silencing.
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Affiliation(s)
- Malika Shamekova
- Department of Plant Pathology & Microbiology, Texas A&M University, College Station, TX 77843, USA
| | - Maria R Mendoza
- Department of Plant Pathology & Microbiology, Texas A&M University, College Station, TX 77843, USA
| | - Yi-Cheng Hsieh
- Department of Plant Pathology & Microbiology, Texas A&M University, College Station, TX 77843, USA
| | - John Lindbo
- Department of Plant Pathology, Ohio State University, Wooster, OH 44691, USA
| | - Rustem T Omarov
- Department of Plant Pathology & Microbiology, Texas A&M University, College Station, TX 77843, USA
| | - Herman B Scholthof
- Department of Plant Pathology & Microbiology, Texas A&M University, College Station, TX 77843, USA.
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16
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Manabayeva SA, Shamekova M, Park JW, Ding XS, Nelson RS, Hsieh YC, Omarov RT, Scholthof HB. Differential requirements for Tombusvirus coat protein and P19 in plants following leaf versus root inoculation. Virology 2013; 439:89-96. [PMID: 23490050 DOI: 10.1016/j.virol.2013.01.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Revised: 11/02/2012] [Accepted: 01/16/2013] [Indexed: 12/19/2022]
Abstract
Traditional virus inoculation of plants involves mechanical rubbing of leaves, whereas in nature viruses like Tomato bushy stunt virus (TBSV) are often infected via the roots. A method was adapted to compare leaf versus root inoculation of Nicotiana benthamiana and tomato with transcripts of wild-type TBSV (wtTBSV), a capsid (Tcp) replacement construct expressing GFP (T-GFP), or mutants not expressing the silencing suppressor P19 (TBSVΔp19). In leaves, T-GFP remained restricted to the cells immediately adjacent to the site of inoculation, unless Tcp was expressed in trans from a Potato virus X vector; while T-GFP inoculation of roots gave green fluorescence in upper tissues in the absence of Tcp. Conversely, leaf inoculation with wtTBSV or TBSVΔp19 transcripts initiated systemic infections, while upon root inoculation this only occurred with wtTBSV, not with TBSVΔp19. Evidently the contribution of Tcp or P19 in establishing systemic infections depends on the point-of-entry of TBSV in the plants.
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Affiliation(s)
- Shuga A Manabayeva
- Department of Plant Pathology and Microbiology, Texas A&M University, 2132 TAMU, College Station, TX 77843, USA
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17
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Angel CA, Schoelz JE. A survey of resistance to Tomato bushy stunt virus in the genus Nicotiana reveals that the hypersensitive response is triggered by one of three different viral proteins. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2013; 26:240-8. [PMID: 23075040 DOI: 10.1094/mpmi-06-12-0157-r] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
In this study, we screened 22 Nicotiana spp. for resistance to the tombusviruses Tomato bushy stunt virus (TBSV), Cucumber necrosis virus, and Cymbidium ringspot virus. Eighteen species were resistant, and resistance was manifested in at least two different categories. In all, 13 species responded with a hypersensitive response (HR)-type resistance, whereas another five were resistant but either had no visible response or responded with chlorotic lesions rather than necrotic lesions. Three different TBSV proteins were found to trigger HR in Nicotiana spp. in an agroinfiltration assay. The most common avirulence (avr) determinant was the TBSV coat protein P41, a protein that had not been previously recognized as an avr determinant. A mutational analysis confirmed that the coat protein rather than the viral RNA sequence was responsible for triggering HR, and it triggered HR in six species in the Alatae section. The TBSV P22 movement protein triggered HR in two species in section Undulatae (Nicotiana glutinosa and N. edwardsonii) and one species in section Alatae (N. forgetiana). The TBSV P19 RNA silencing suppressor protein triggered HR in sections Sylvestres (N. sylvestris), Nicotiana (N. tabacum), and Alatae (N. bonariensis). In general, Nicotiana spp. were capable of recognizing only one tombusvirus avirulence determinant, with the exceptions of N. bonariensis and N. forgetiana, which were each able to recognize P41, as well as P19 and P22, respectively. Agroinfiltration failed to detect the TBSV avr determinants responsible for triggering HR in N. arentsii, N. undulata, and N. rustica. This study illustrates the breadth and variety of resistance responses to tombusviruses that exists in the Nicotiana genus.
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Affiliation(s)
- Carlos A Angel
- Division of Plant Sciences, University of Missouri, Columbia, MO 65211, USA
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18
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Liu X, Houzet L, Jeang KT. Tombusvirus P19 RNA silencing suppressor (RSS) activity in mammalian cells correlates with charged amino acids that contribute to direct RNA-binding. Cell Biosci 2012; 2:41. [PMID: 23216864 PMCID: PMC3533911 DOI: 10.1186/2045-3701-2-41] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Accepted: 11/21/2012] [Indexed: 12/31/2022] Open
Abstract
Background Tombusvirus P19 is a protein encoded by tomato bushy stunt virus and related tombusviruses. Earlier studies have demonstrated that P19 is an RNA silencing suppressor (RSS) in plant cells. However, it has not been systematically investigated how P19 suppresses RNA interference in various mammalian cell settings. Results We have studied the RSS effect of P19 in mammalian cells, HEK293T, HeLa, and mouse embryonic fibroblasts. We have individually mutated 18 positively charged residues in P19 and found that 6 of these charged residues in P19 reduce its ability to suppress RNA interference. In each case, the reduction of silencing of RNA interference correlated with the reduced ability by these P19 mutants to bind siRNAs (small interfering RNAs). Conclusions Our findings characterize a class of RNA-binding proteins that function as RSS moieties. We find a tight correlation between positively charged residues in P19 accounting for siRNA-binding and their RSS activity. Because P19’s activity is conserved in plant and animal cells, we conclude that its RSS function unlikely requires cell type-specific co-factors and likely arises from direct RNA-binding.
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Affiliation(s)
- Xiang Liu
- Molecular Virology Section, Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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19
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Kim S, Cho WK, Lee HG, Park SH, Sohn SH, Kim KH. The p19 protein of Grapevine Algerian latent virus is a determinant of systemic infection of Chenopodium quinoa. Virus Res 2012; 165:81-9. [PMID: 22342277 DOI: 10.1016/j.virusres.2012.01.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 01/31/2012] [Accepted: 01/31/2012] [Indexed: 11/29/2022]
Abstract
A previous study showed that both Grapevine Algerian latent virus (GALV) and Tomato bushy stunt virus (TBSV) systemically infect Nicotiana benthamiana, but GALV causes systemic infection whereas TBSV causes only local lesions in Chenopodium quinoa (C. quinoa). We recently isolated GALV strain Naju (GALV-N) from Limonium sinense and TBSV strain Sacheon (TBSV-S) from tomato. Both viruses belong to the genus Tombusvirus and have a similar genome organization. To identify determinants of systemic infection of GALV-N in C. quinoa in the current study, we generated infectious clones and capsid protein (CP)-deletion clones for the two viruses and confirmed that CP of GALV-N is required for systemic infection of C. quinoa due to its primary structural role in virus assembly. Through the use of chimeras, we identified a viral factor in addition to CP that contributes to systemic infection by GALV-N. Inactivation of the p19 demonstrated that host-specific activities of p19 are necessary for efficient systemic infection of C. quinoa by GALV-N. Our study is the first report to determine the viral factors required for systemic infection of GALV in C. quinoa.
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Affiliation(s)
- Semin Kim
- Department of Agricultural Biotechnology and Plant Genomics and Breeding Institute, College of Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Republic of Korea
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20
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Scholthof KBG, Adkins S, Czosnek H, Palukaitis P, Jacquot E, Hohn T, Hohn B, Saunders K, Candresse T, Ahlquist P, Hemenway C, Foster GD. Top 10 plant viruses in molecular plant pathology. MOLECULAR PLANT PATHOLOGY 2011; 12:938-54. [PMID: 22017770 PMCID: PMC6640423 DOI: 10.1111/j.1364-3703.2011.00752.x] [Citation(s) in RCA: 569] [Impact Index Per Article: 43.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Many scientists, if not all, feel that their particular plant virus should appear in any list of the most important plant viruses. However, to our knowledge, no such list exists. The aim of this review was to survey all plant virologists with an association with Molecular Plant Pathology and ask them to nominate which plant viruses they would place in a 'Top 10' based on scientific/economic importance. The survey generated more than 250 votes from the international community, and allowed the generation of a Top 10 plant virus list for Molecular Plant Pathology. The Top 10 list includes, in rank order, (1) Tobacco mosaic virus, (2) Tomato spotted wilt virus, (3) Tomato yellow leaf curl virus, (4) Cucumber mosaic virus, (5) Potato virus Y, (6) Cauliflower mosaic virus, (7) African cassava mosaic virus, (8) Plum pox virus, (9) Brome mosaic virus and (10) Potato virus X, with honourable mentions for viruses just missing out on the Top 10, including Citrus tristeza virus, Barley yellow dwarf virus, Potato leafroll virus and Tomato bushy stunt virus. This review article presents a short review on each virus of the Top 10 list and its importance, with the intent of initiating discussion and debate amongst the plant virology community, as well as laying down a benchmark, as it will be interesting to see in future years how perceptions change and which viruses enter and leave the Top 10.
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Affiliation(s)
- Karen-Beth G Scholthof
- Department of Plant Pathology and Microbiology, 2132 TAMU, Texas A&M University, College Station, TX 77843-2132, USA
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21
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Seaberg BL, Hsieh YC, Scholthof KBG, Scholthof HB. Host impact on the stability of a plant virus gene vector as measured by a new fluorescent local lesion passaging assay. J Virol Methods 2011; 179:289-94. [PMID: 22119627 DOI: 10.1016/j.jviromet.2011.11.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 10/28/2011] [Accepted: 11/09/2011] [Indexed: 12/18/2022]
Abstract
Viruses can be used as vectors for transient expression of proteins in plants but frequently foreign gene inserts are not maintained stably over time due to recombination events. In this study the hypothesis was that the choice of plant host affects the foreign gene retention level by a Tomato bushy stunt virus (TBSV) vector expressing green fluorescent protein (GFP). To accomplish this, a novel virus vector integrity bioassay was developed based on an old concept, whereby RNA transcripts of the TBSV-GFP vector were rub-inoculated onto leaves of test plants, and at 3 days post inoculation (dpi), these leaves were used as inoculum for passage to cowpea (Vigna unguiculata), a local lesion host. Chlorotic lesions at points of virus infection were counted on cowpea at 4dpi and then the leaves were exposed to ultraviolet light to count green fluorescent foci. These tests with seven different plant species covering five families showed that the percentage of green fluorescent lesions varied on the cowpea indicator plants in a host-dependent manner. For instance, the vector was relatively unstable in Nicotiana benthamiana, tomato, bean, and spinach, but compared to those its stability in lettuce was significantly improved (~3-fold). This host-dependent effect suggests that some plants may present a more suitable environment than others to support or maintain optimum levels of virus vector-mediated foreign gene expression.
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Affiliation(s)
- Bonnie L Seaberg
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843, USA
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22
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Scholthof HB, Alvarado VY, Vega-Arreguin JC, Ciomperlik J, Odokonyero D, Brosseau C, Jaubert M, Zamora A, Moffett P. Identification of an ARGONAUTE for antiviral RNA silencing in Nicotiana benthamiana. PLANT PHYSIOLOGY 2011; 156:1548-55. [PMID: 21606315 PMCID: PMC3135948 DOI: 10.1104/pp.111.178764] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Accepted: 05/09/2011] [Indexed: 05/21/2023]
Abstract
ARGONAUTE proteins (AGOs) are known to be key components of the RNA silencing mechanism in eukaryotes that, among other functions, serves to protect against viral invaders. Higher plants encode at least 10 individual AGOs yet the role played by many in RNA silencing-related antiviral defense is largely unknown, except for reports that AGO1, AGO2, and AGO7 play an antiviral role in Arabidopsis (Arabidopsis thaliana). In the plant virus model host Nicotiana benthamiana, Tomato bushy stunt virus (TBSV) P19 suppressor mutants are very susceptible to RNA silencing. Here, we report that a N. benthamiana AGO (NbAGO) with similarity to Arabidopsis AGO2, is involved in antiviral defense against TBSV. The activity of this NbAGO2 is shown to be directly associated with anti-TBSV RNA silencing, while its inactivation does not influence silencing of transiently expressed transgenes. Thus, the role of NbAGO2 might be primarily for antiviral defense.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Peter Moffett
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas 77843 (H.B.S., V.Y.A., J.C., D.O.); Boyce Thompson Institute for Plant Research, Ithaca, New York 14853 (J.C.V.-A., M.J., A.Z., P.M.); Département de Biologie, Université de Sherbrooke, Quebec, Canada J1K 2R1 (C.B., P.M.)
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23
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Ciomperlik JJ, Omarov RT, Scholthof HB. An antiviral RISC isolated from Tobacco rattle virus-infected plants. Virology 2011; 412:117-24. [PMID: 21272908 PMCID: PMC3056891 DOI: 10.1016/j.virol.2010.12.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Revised: 09/12/2010] [Accepted: 12/13/2010] [Indexed: 11/28/2022]
Abstract
The RNAi model predicts that during antiviral defense a RNA-induced silencing complex (RISC) is programmed with viral short-interfering RNAs (siRNAs) to target the cognate viral RNA for degradation. We show that infection of Nicotiana benthamiana with Tobacco rattle virus (TRV) activates an antiviral nuclease that specifically cleaves TRV RNA in vitro. In agreement with known RISC properties, the nuclease activity was inhibited by NaCl and EDTA and stimulated by divalent metal cations; a novel property was its preferential targeting of elongated RNA molecules. Intriguingly, the specificity of the TRV RISC could be reprogrammed by exogenous addition of RNA (containing siRNAs) from plants infected with an unrelated virus, resulting in a newly acquired ability of RISC to target this heterologous genome in vitro. Evidently the virus-specific nuclease complex from N. benthamiana represents a genuine RISC that functions as a readily employable and reprogrammable antiviral defense unit.
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Affiliation(s)
| | | | - Herman B. Scholthof
- Department of Plant Pathology and Microbiology, Texas A&M University, 2132 TAMU, College Station, TX 77843
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24
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Angel CA, Hsieh YC, Schoelz JE. Comparative analysis of the capacity of tombusvirus P22 and P19 proteins to function as avirulence determinants in Nicotiana species. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2011; 24:91-9. [PMID: 20977306 DOI: 10.1094/mpmi-04-10-0089] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We have used an agroinfiltration assay for a comparative study of the roles of tombusvirus P22 and P19 proteins in elicitation of hypersensitive response (HR)-like necrosis and the role of P19 in silencing suppression in Nicotiana species. The advantage of agroinfiltration rather than expression in plant virus vectors is that putative viral avirulence proteins can be evaluated in isolation, eliminating the possibility of synergistic effects with other viral proteins. We found that tombusvirus P22 and P19 proteins elicited HR-like necrosis in certain Nicotiana species but, also, that Nicotiana species could recognize subtle differences in sequence between these proteins. Furthermore, Nicotiana species that responded with systemic necrosis to virion inoculations responded to agroinfiltration of tombusvirus P19 with a very weak and delayed necrosis, indicating that the rapid HR-like necrosis was associated with putative resistance genes and a plant defense response that limited the spread of the virus. Tombusvirus P19 proteins also appeared to differ in their effectiveness as silencing suppressors; in our assay, the P19 proteins of Cymbidium ringspot virus and Tomato bushy stunt virus were stronger silencing suppressors than Cucumber necrosis virus P20. Finally, we show that agroinfiltration can be used to track the presence of putative plant resistance genes in Nicotiana species that target either tombusvirus P19 or P22.
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Affiliation(s)
- Carlos A Angel
- Division of Plant Sciences, University of Missouri, Columbia, MO 65211, USA
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25
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Everett AL, Scholthof HB, Scholthof KBG. Satellite panicum mosaic virus coat protein enhances the performance of plant virus gene vectors. Virology 2009; 396:37-46. [PMID: 19903565 DOI: 10.1016/j.virol.2009.10.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Revised: 08/09/2009] [Accepted: 10/03/2009] [Indexed: 01/16/2023]
Abstract
The coat protein of satellite panicum mosaic virus (SPCP) is known to effectively protect its cognate RNA from deleterious events, and here, we tested its stabilizing potential for heterologous virus-based gene vectors in planta. In support of this, a Potato virus X (PVX) vector carrying the SPMV capsid protein (PVX-SPCP) gene was stable for at least three serial systemic passages through Nicotiana benthamiana. To test the effect of SPCP in trans, PVX-SPCP was co-inoculated onto N. benthamiana together with a Tomato bushy stunt virus (TBSV) vector carrying a green fluorescent protein (GFP) gene that normally does not support systemic GFP expression. In contrast, co-inoculation of TBSV-GFP plus PVX-SPCP resulted in GFP accumulation and concomitant green fluorescent spots in upper, non-inoculated leaves in a temperature-responsive manner. These results suggest that the multifaceted SPMV CP has intriguing effects on virus-host interactions that surface in heterologous systems.
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Affiliation(s)
- Anthany L Everett
- Department of Plant Pathology and Microbiology, 2132 TAMU, Texas A&M University, College Station, TX 77843, USA
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26
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Hsieh YC, Omarov RT, Scholthof HB. Diverse and newly recognized effects associated with short interfering RNA binding site modifications on the Tomato bushy stunt virus p19 silencing suppressor. J Virol 2009; 83:2188-200. [PMID: 19052093 PMCID: PMC2643727 DOI: 10.1128/jvi.02186-08] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Accepted: 11/21/2008] [Indexed: 12/15/2022] Open
Abstract
The Tomato bushy stunt virus-encoded P19 forms dimers that bind duplex short interfering RNAs (siRNAs) to suppress RNA silencing. P19 is also involved in multiple host-specific activities, including the elicitation of symptoms, and in local and/or systemic spread. To study the correlation between those various roles and the siRNA binding by P19, predicted siRNA-interacting sites were modified. Twenty-two mutants were generated and inoculated onto Nicotiana benthamiana plants, to reveal that (i) they were all infectious, (ii) symptom differences did not correlate strictly with mutation-associated variation in P19 accumulation, and (iii) substitutions affecting a central domain of P19 generally exhibited symptoms more severe than for mutations affecting peripheral regions. Three mutants selected to represent separate phenotypic categories all displayed a substantially reduced ability to sequester siRNA. Consequently, these three mutants were compromised for systemic virus spread in P19-dependent hosts but had differential plant species-dependent effects on the symptom severity. One mutant in particular caused relatively exacerbated symptoms, exemplified by extensive morphological leaf deformations in N. benthamiana; this was especially remarkable because P19 was undetectable. Another striking feature of this mutant was that only within a few days after infection, viral RNA was cleared by silencing. One more original property was that host RNAs and proteins (notably, the P19-interactive Hin19 protein) were also susceptible to degradation in these infected N. benthamiana plants but not in spinach. In conclusion, even though siRNA binding by P19 is a key functional property, compromised siRNA sequestration can result in novel and diverse host-dependent properties.
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Affiliation(s)
- Yi-Cheng Hsieh
- Department of Plant Pathology and Microbiology, Texas A&M University, 2132 TAMU, College Station, Texas 77843, USA
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27
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Pignatta D, Kumar P, Turina M, Dandekar A, Falk BW. Quantitative analysis of efficient endogenous gene silencing in Nicotiana benthamiana plants using tomato bushy stunt virus vectors that retain the capsid protein gene. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2007; 20:609-18. [PMID: 17555269 DOI: 10.1094/mpmi-20-6-0609] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Tomato bushy stunt virus (TBSV) coat protein (CP) replacement vectors have been used previously to silence transgenes (e.g., the green fluorescent protein gene) but have not been effective for silencing endogenous plant genes. New TBSV vectors which retained the CP gene were developed by engineering an XhoI restriction site in three positions (3f, CEB, and CEA) of the pTBSV-100 infectious clone. Magnesium chelatase (ChlH) and phytoene desaturase (PDS) were chosen as targets for endogenous gene silencing. Initial experiments using CP replacement vectors with a 230-bp sense or antisense ChlH insert gave a silencing phenotype prominent only in the first new leaves above those inoculated. No silencing phenotype was apparent beyond these leaves whereas, for PDS, no silencing phenotype was observed. When plants were inoculated with the XhoI insert vectors containing ChlH and PDS sequences, plants showed a silencing phenotype extensively throughout the challenged plant, indicating an improved ability for virus movement and silencing in Nicotiana benthamiana host plants. Silencing efficiencies were quantified using realtime reverse-transcription polymerase chain reaction, indicating specific silencing effects of each individual silencing vector. Only one recombinant vector (pPD-3f5), where the XhoI insert was at the 3' end of the CP gene, failed to give effective silencing. Here, we show that our new CP-retaining TBSV vectors (CEA-CEB) form typical TBSV virions, retain silencing inserts of variable lengths (110 to 260 nucleotides), and can systemically silence endogenous genes in N. benthamiana.
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Affiliation(s)
- Daniela Pignatta
- Dipartimento di Scienze e Tecnologie Agroambientali, Bologna, Italy
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28
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Omarov RT, Ciomperlik JJ, Scholthof HB. RNAi-associated ssRNA-specific ribonucleases in Tombusvirus P19 mutant-infected plants and evidence for a discrete siRNA-containing effector complex. Proc Natl Acad Sci U S A 2007; 104:1714-9. [PMID: 17244709 PMCID: PMC1785274 DOI: 10.1073/pnas.0608117104] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2006] [Indexed: 11/18/2022] Open
Abstract
Tomato bushy stunt virus (TBSV) and other tombusviruses encode a p19 protein (P19), which is a suppressor of RNAi. Wild-type TBSV or p19-defective mutants initially show a similar infection course in Nicotiana benthamiana, but the absence of an active P19 results in viral RNA degradation followed by recovery from infection. P19 homodimers sequester 21-nt virus-derived duplex siRNAs, and it is thought that this prevents the programming of an antiviral RNA-induced silencing complex to avoid viral RNA degradation. Here we report on chromatographic fractionation (gel filtration, ion exchange, and hydroxyapatite) of extracts from healthy or infected Nicotiana benthamiana plants in combination with in vitro assays for ribonuclease activity and detection of TBSV-derived siRNAs. Only extracts of plants infected with p19 mutants provided a source of sequence-nonspecific but ssRNA-targeted in vitro ribonuclease activity that coeluted with components of a wide molecular weight range. In addition, we isolated a discrete approximately 500-kDa protein complex that contained approximately 21-nt TBSV-derived siRNAs and that exhibited ribonuclease activity that was TBSV sequence-preferential, ssRNA-specific, divalent cation-dependent, and insensitive to a ribonuclease inhibitor. We believe that this study provides biochemical evidence for a virus-host system that infection in the absence of a fully active RNAi suppressor induces ssRNA-specific ribonuclease activity, including that conferred by a RNA-induced silencing complex, which is likely the cause for the recovery of plants from infection.
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Affiliation(s)
- Rustem T. Omarov
- Department of Plant Pathology and Microbiology and Intercollegiate Faculty of Virology, Texas A&M University, 2132 TAMU, College Station, TX 77843
| | - Jessica J. Ciomperlik
- Department of Plant Pathology and Microbiology and Intercollegiate Faculty of Virology, Texas A&M University, 2132 TAMU, College Station, TX 77843
| | - Herman B. Scholthof
- Department of Plant Pathology and Microbiology and Intercollegiate Faculty of Virology, Texas A&M University, 2132 TAMU, College Station, TX 77843
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29
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Abstract
Since its discovery in the late 1980s, the status of the Tombusvirus-encoded p19 protein (P19) changed from being thought obsolete to its identification a decade later as an important viral pathogenicity factor. The recent finding that P19 suppresses RNA interference (RNAi) by appropriating short interfering RNAs led to its widespread use as an RNAi-probing tool in various plant and animal models. Here, I discuss how our knowledge of p19 has developed over the years, with emphasis on the relevance of understanding its biological roles during Tombusvirus infection of plants.
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Affiliation(s)
- Herman B Scholthof
- Department of Plant Pathology and Microbiology and Intercollegiate Faculty of Virology, Texas A&M University, 2132 TAMU, College Station, Texas 77843, USA.
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Omarov R, Sparks K, Smith L, Zindovic J, Scholthof HB. Biological relevance of a stable biochemical interaction between the tombusvirus-encoded P19 and short interfering RNAs. J Virol 2006; 80:3000-8. [PMID: 16501109 PMCID: PMC1395443 DOI: 10.1128/jvi.80.6.3000-3008.2006] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2005] [Accepted: 12/17/2005] [Indexed: 11/20/2022] Open
Abstract
The Tomato bushy stunt virus (TBSV)-encoded p19 protein (P19) is widely used as a robust tool to suppress RNA interference (RNAi) in various model organisms. P19 dimers appropriate 21-nucleotide (nt) duplex short interfering RNAs (siRNAs) generated by Dicer presumably to prevent programming of the RNA-induced silencing complex (RISC). In the context of virus infection, this model predicts that P19 mutants compromised for siRNA binding cannot prevent RISC-mediated degradation of TBSV RNA and thus reduce viral pathogenicity. To test this, we used P19/43 (R-->W), which is less pathogenic than wild-type P19 (wtP19), and P19/75-78 (RR-->GG), with pathogenicity properties (i.e., viral spread and symptom induction) comparable to those of a P19-null mutant. We demonstrate that P19/43 still suppresses RNAi-mediated viral RNA degradation in infected Nicotiana benthamiana, while P19/75-78 is unable to prevent this clearance of viral RNA, leading to an irreversible recovery phenotype. Gel filtration and immunoprecipitation assays show that at the onset of the infection, wtP19, P19/43, and P19/75-78 readily accumulate, and they form dimers. The wtP19 is stably associated with duplex approximately 21-nt TBSV siRNAs, while P19/75-78 does not bind these molecules, and the electrostatic interaction of P19/43 with siRNAs is perturbed for approximately 21-nt duplexes but not for longer siRNAs. This is the first clear demonstration of a direct correlation between a novel structurally orchestrated siRNA binding of an RNAi suppressor and its roles in viral pathogenesis. The findings should be particularly valuable for the RNAi field in general because the P19 mutants enable precise determination of siRNA appropriation effects.
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Affiliation(s)
- Rustem Omarov
- Department of Plant Pathology and Microbiology, Texas A&M University, 2132 TAMU, College Station, Texas 77843, USA
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