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Mahillon M, Brodard J, Kellenberger I, Blouin AG, Schumpp O. A novel weevil-transmitted tymovirus found in mixed infection on hollyhock. Virol J 2023; 20:17. [PMID: 36710353 PMCID: PMC9885571 DOI: 10.1186/s12985-023-01976-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 01/24/2023] [Indexed: 01/31/2023] Open
Abstract
Leaves of hollyhock (Alcea rosea) exhibiting vein chlorosis and yellow mosaic symptoms were collected at public sites in Lausanne and Nyon, two cities of western Switzerland. Diagnostic methods untangled in samples from both sites the mixed infections of a novel isometric virus, tentatively named "Alcea yellow mosaic virus" (AYMV) with the carlavirus Gaillardia latent virus. A new potyvirus was also identified in samples from Nyon. A combination of Illumina, Nanopore and Sanger sequencing was necessary to assemble the full-length genome of AYMV, revealing an exceptionally high cytidine content and other features typically associated with members of the genus Tymovirus. The host range of AYMV was found to be restricted to mallows, including ornamentals as well as economically important plants. Phylogenetic analyses further showed that AYMV belongs to a Tymovirus subclade that also gathers the other mallow-infecting members. The virus was readily transmitted by sap inoculation, and the weevil species Aspidapion radiolus was evidenced as a vector. Transmission assays using another weevil or other insect species did not succeed, and seed transmission was not observed.
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Affiliation(s)
- Mathieu Mahillon
- grid.417771.30000 0004 4681 910XResearch Group Virology, Bacteriology and Phytoplasmology, Agroscope, Nyon, Switzerland
| | - Justine Brodard
- grid.417771.30000 0004 4681 910XResearch Group Virology, Bacteriology and Phytoplasmology, Agroscope, Nyon, Switzerland
| | - Isabelle Kellenberger
- grid.417771.30000 0004 4681 910XResearch Group Virology, Bacteriology and Phytoplasmology, Agroscope, Nyon, Switzerland
| | - Arnaud G. Blouin
- grid.417771.30000 0004 4681 910XResearch Group Virology, Bacteriology and Phytoplasmology, Agroscope, Nyon, Switzerland
| | - Olivier Schumpp
- Research Group Virology, Bacteriology and Phytoplasmology, Agroscope, Nyon, Switzerland.
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2
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Role of an RNA pseudoknot involving the polyA tail in replication of Pepino mosaic potexvirus and related plant viruses. Sci Rep 2022; 12:11532. [PMID: 35798958 PMCID: PMC9262919 DOI: 10.1038/s41598-022-15598-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 06/27/2022] [Indexed: 01/11/2023] Open
Abstract
Pepino mosaic virus (PepMV) is a potexvirus of the family Alphaflexiviridae within the order of Tymovirales that threatens tomato production worldwide. PepMV possesses a positive-strand RNA genome with a 5′-methylguanosine cap and a 3′-polyA tail. Previously, using partially-purified viral RNA polymerase important secondary structures within the 3′-untranslated region (UTR) of PepMV RNA were identified. Here we show that an RNA pseudoknot can be formed in the 3′-UTR that includes part of the polyA tail. Using protoplasts, we demonstrate that the pseudoknot is required for replication of PepMV RNA. Mutational analysis and native gel electrophoresis further show that the pseudoknot is stabilized by UAU base triples, as is the human telomerase RNA pseudoknot. The presence of a pseudoknot in several other members of the Alpha- and Betaflexiviridae is supported by covariance analysis and native gel electrophoresis of other potexvirus, capillovirus and trichovirus RNAs. The ubiquitous presence of the pseudoknot in viruses of the Betaflexiviridae, suggests that the pseudoknot is a typical trait of the Betaflexiviridae that may have been adopted by many potexviruses during evolution.
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3
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Wu S, Li X, Wang G. tRNA-like structures and their functions. FEBS J 2021; 289:5089-5099. [PMID: 34117728 DOI: 10.1111/febs.16070] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 05/12/2021] [Accepted: 06/10/2021] [Indexed: 11/27/2022]
Abstract
tRNA-like structures (TLSs) were first identified in the RNA genomes of turnip yellow mosaic virus. Since then, TLSs have been found in many other species including mammals, and the RNAs harboring these structures range from viral genomic RNAs to mRNAs and noncoding RNAs. Some progress has also been made on understanding their functions that include regulation of RNA replication, translation enhancement, RNA-protein interaction, and more. In this review, we summarize the current knowledge about the regulations and functions of these TLSs. Possible future directions of the field are also briefly discussed.
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Affiliation(s)
- Sipeng Wu
- State Key Laboratory for Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Fujian, China
| | - Xiang Li
- State Key Laboratory for Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Fujian, China
| | - Geng Wang
- State Key Laboratory for Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Fujian, China
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4
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Green KJ, Mollov D, Tran LT, Alvarez-Quinto RA, Ochoa JB, Quito-Avila DF, Karasev AV. Characterization of a New Tymovirus Causing Stunting and Chlorotic Mosaic in Naranjilla (Solanum quitoense). PLANT DISEASE 2018; 102:911-918. [PMID: 30673388 DOI: 10.1094/pdis-10-17-1534-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Naranjilla ("little orange"), also known as lulo (Solanum quitoense Lam.), is a perennial shrub species cultivated in the Andes for fresh fruit and juice production. In 2015, a naranjilla plant exhibiting stunting, mosaic, and chlorotic spots was sampled in the Pastaza province of Ecuador and maintained under greenhouse conditions. An infectious agent was mechanically transmitted to indicator plants and was subjected to biological and molecular characterization. Spherical particles approximately 30 nm in diameter, composed of a single 20-kDa capsid protein, were observed under an electron microscope in infected naranjilla plants. High-throughput sequencing conducted on inoculated Nicotiana benthamiana plants produced a single sequence contig sharing the closest relationship with several tymoviruses. The entire 6,245-nucleotide genome of a new tymovirus was amplified using reverse-transcription polymerase chain reaction and resequenced with the Sanger methodology. The genome had three open reading frames typical of tymoviruses, and displayed a whole-genome nucleotide identity level with the closest tymovirus, Eggplant mosaic virus, at 71% (90% coverage). This tymovirus from naranjilla was able to systemically infect eggplant, tamarillo, N. benthamiana, and naranjilla. In naranjilla, it produced mosaic, chlorotic spots, and stunting, similar to the symptoms observed in the original plant. The virus was unable to infect potato and tobacco and unable to systemically infect pepper plants, replicating only in inoculated leaves. We concluded that this virus represented a new tymovirus infecting naranjilla, and proposed the tentative name Naranjilla chlorotic mosaic virus (NarCMV).
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Affiliation(s)
- Kelsie J Green
- Department of Entomology, Plant Pathology and Nematology (EPPN), University of Idaho, Moscow
| | - Dimitre Mollov
- United States Department of Agriculture-Agricultural Research Service, National Germplasm Resources Laboratory, Beltsville, MD
| | | | - Robert A Alvarez-Quinto
- Centro de Investigaciones Biotecnológicas del Ecuador and Facultad de Ciencias de la Vida, Escuela Superior Politécnica del Litoral, ESPOL, Guayaquil, Ecuador
| | - Jose B Ochoa
- Instituto Nacional Autónomo de Investigaciones Agropecuarias, Quito, Ecuador
| | - Diego F Quito-Avila
- Centro de Investigaciones Biotecnológicas del Ecuador and Facultad de Ciencias de la Vida, Escuela Superior Politécnica del Litoral
| | - Alexander V Karasev
- Department of EPPN and Bioinformatics and Computational Biology Program, University of Idaho
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5
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Cantara WA, Olson ED, Musier-Forsyth K. Analysis of RNA structure using small-angle X-ray scattering. Methods 2017; 113:46-55. [PMID: 27777026 PMCID: PMC5253320 DOI: 10.1016/j.ymeth.2016.10.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 10/10/2016] [Accepted: 10/20/2016] [Indexed: 11/22/2022] Open
Abstract
In addition to their role in correctly attaching specific amino acids to cognate tRNAs, aminoacyl-tRNA synthetases (aaRS) have been found to possess many alternative functions and often bind to and act on other nucleic acids. In contrast to the well-defined 3D structure of tRNA, the structures of many of the other RNAs recognized by aaRSs have not been solved. Despite advances in the use of X-ray crystallography (XRC), nuclear magnetic resonance (NMR) spectroscopy and cryo-electron microscopy (cryo-EM) for structural characterization of biomolecules, significant challenges to solving RNA structures still exist. Recently, small-angle X-ray scattering (SAXS) has been increasingly employed to characterize the 3D structures of RNAs and RNA-protein complexes. SAXS is capable of providing low-resolution tertiary structure information under physiological conditions and with less intensive sample preparation and data analysis requirements than XRC, NMR and cryo-EM. In this article, we describe best practices involved in the process of RNA and RNA-protein sample preparation, SAXS data collection, data analysis, and structural model building.
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Affiliation(s)
- William A Cantara
- Department of Chemistry and Biochemistry, Center for Retrovirus Research, and Center for RNA Biology, The Ohio State University, Columbus, OH 43210, United States
| | - Erik D Olson
- Department of Chemistry and Biochemistry, Center for Retrovirus Research, and Center for RNA Biology, The Ohio State University, Columbus, OH 43210, United States
| | - Karin Musier-Forsyth
- Department of Chemistry and Biochemistry, Center for Retrovirus Research, and Center for RNA Biology, The Ohio State University, Columbus, OH 43210, United States.
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6
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Exploiting tRNAs to Boost Virulence. Life (Basel) 2016; 6:life6010004. [PMID: 26797637 PMCID: PMC4810235 DOI: 10.3390/life6010004] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 01/08/2016] [Accepted: 01/14/2016] [Indexed: 01/22/2023] Open
Abstract
Transfer RNAs (tRNAs) are powerful small RNA entities that are used to translate nucleotide language of genes into the amino acid language of proteins. Their near-uniform length and tertiary structure as well as their high nucleotide similarity and post-transcriptional modifications have made it difficult to characterize individual species quantitatively. However, due to the central role of the tRNA pool in protein biosynthesis as well as newly emerging roles played by tRNAs, their quantitative assessment yields important information, particularly relevant for virus research. Viruses which depend on the host protein expression machinery have evolved various strategies to optimize tRNA usage—either by adapting to the host codon usage or encoding their own tRNAs. Additionally, several viruses bear tRNA-like elements (TLE) in the 5′- and 3′-UTR of their mRNAs. There are different hypotheses concerning the manner in which such structures boost viral protein expression. Furthermore, retroviruses use special tRNAs for packaging and initiating reverse transcription of their genetic material. Since there is a strong specificity of different viruses towards certain tRNAs, different strategies for recruitment are employed. Interestingly, modifications on tRNAs strongly impact their functionality in viruses. Here, we review those intersection points between virus and tRNA research and describe methods for assessing the tRNA pool in terms of concentration, aminoacylation and modification.
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7
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Li P, Lin Y, Zhang H, Wang S, Qiu D, Guo L. Molecular characterization of a novel mycovirus of the family Tymoviridae isolated from the plant pathogenic fungus Fusarium graminearum. Virology 2015; 489:86-94. [PMID: 26744993 DOI: 10.1016/j.virol.2015.12.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 12/05/2015] [Accepted: 12/13/2015] [Indexed: 11/16/2022]
Abstract
We isolated a novel mycovirus, Fusarium graminearum mycotymovirus 1 (FgMTV1/SX64), which is related to members of the family Tymoviridae, from the plant pathogenic fungus F. graminearum strain SX64. The complete 7863 nucleotide sequence of FgMTV1/SX64, excluding the poly (A) tail, was determined. The genome of FgMTV1/SX64 is predicted to contain four open reading frames (ORFs). The largest ORF1 is 6723 nucleotides (nt) in length and encodes a putative polyprotein of 2242 amino acids (aa), which contains four conserved domains, a methyltransferase (Mtr), tymovirus endopeptidase (Pro), viral RNA helicase (Hel), and RNA-dependent RNA polymerase (RdRp), of the replication-associated proteins (RPs) of the positive-strand RNA viruses. ORFs 2-4 putatively encode three putative small hypothetical proteins, but their functions are still unknown. Sequence alignments and phylogenetic analyses based on the putative RP protein and the three conserved domains (Mtr, Hel and RdRp) showed that FgMTV1/SX64 is most closely related to, but distinctly branched from, the viruses from the family Tymoviridae. Although FgMTV1/SX64 infection caused mild or no effect on conidia production, biomass and virulence of its host F. graminearum strain SX64, its infection had significant effects on the growth rate, colony diameter and deoxynivalenol (DON) production. This is the first molecular characterization of a tymo-like mycovirus isolated from a plant pathogenic fungus. It is proposed that the mycovirus FgMTV1/SX64 is a representative member of new proposed lineage Mycotymovirus in the family Tymoviridae.
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Affiliation(s)
- Pengfei Li
- State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Science, Beijing, China
| | - Yanhong Lin
- State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Science, Beijing, China
| | - Hailong Zhang
- State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Science, Beijing, China
| | - Shuangchao Wang
- State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Science, Beijing, China
| | - Dewen Qiu
- State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Science, Beijing, China
| | - Lihua Guo
- State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Science, Beijing, China.
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8
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Characterization of a novel tymovirus on tomato plants in Brazil. Virus Genes 2012; 46:190-4. [DOI: 10.1007/s11262-012-0830-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2012] [Accepted: 09/20/2012] [Indexed: 11/25/2022]
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9
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Al-Khatib RM, Rashid NAA, Abdullah R. Thermodynamic Heuristics with Case-Based Reasoning: Combined Insights for RNA Pseudoknot Secondary Structure. J Biomol Struct Dyn 2011; 29:1-26. [DOI: 10.1080/07391102.2011.10507373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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10
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Sperschneider J, Datta A, Wise MJ. Heuristic RNA pseudoknot prediction including intramolecular kissing hairpins. RNA (NEW YORK, N.Y.) 2011; 17:27-38. [PMID: 21098139 PMCID: PMC3004063 DOI: 10.1261/rna.2394511] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Accepted: 10/17/2010] [Indexed: 05/30/2023]
Abstract
Pseudoknots are an essential feature of RNA tertiary structures. Simple H-type pseudoknots have been studied extensively in terms of biological functions, computational prediction, and energy models. Intramolecular kissing hairpins are a more complex and biologically important type of pseudoknot in which two hairpin loops form base pairs. They are hard to predict using free energy minimization due to high computational requirements. Heuristic methods that allow arbitrary pseudoknots strongly depend on the quality of energy parameters, which are not yet available for complex pseudoknots. We present an extension of the heuristic pseudoknot prediction algorithm DotKnot, which covers H-type pseudoknots and intramolecular kissing hairpins. Our framework allows for easy integration of advanced H-type pseudoknot energy models. For a test set of RNA sequences containing kissing hairpins and other types of pseudoknot structures, DotKnot outperforms competing methods from the literature. DotKnot is available as a web server under http://dotknot.csse.uwa.edu.au.
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Affiliation(s)
- Jana Sperschneider
- School of Computer Science and Software Engineering, University of Western Australia, Perth WA 6009, Australia.
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11
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Dreher TW. Viral tRNAs and tRNA-like structures. WILEY INTERDISCIPLINARY REVIEWS-RNA 2010; 1:402-14. [PMID: 21956939 DOI: 10.1002/wrna.42] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Viruses commonly exploit or modify some aspect of tRNA biology. Large DNA viruses, especially bacteriophages, phycodnaviruses, and mimiviruses, produce their own tRNAs, apparently to adjust translational capacity during infection. Retroviruses recruit specific host tRNAs for use in priming the reverse transcription of their genome. Certain positive-strand RNA plant viral genomes possess 3'-tRNA-like structures (TLSs) that are built quite differently from authentic tRNAs, and yet efficiently recapitulate several properties of tRNAs. The structures and roles of these TLSs are discussed, emphasizing the variety in both structure and function.
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Affiliation(s)
- Theo W Dreher
- Department of Microbiology and Center for Genome Research and Bioinformatics, Oregon State University, Corvallis, OR 97331, USA.
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12
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Genomic and biological characterization of chiltepín yellow mosaic virus, a new tymovirus infecting Capsicum annuum var. aviculare in Mexico. Arch Virol 2010; 155:675-84. [PMID: 20229325 DOI: 10.1007/s00705-010-0639-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2009] [Accepted: 02/24/2010] [Indexed: 01/20/2023]
Abstract
The characterization of viruses infecting wild plants is a key step towards understanding the ecology of plant viruses. In this work, the complete genomic nucleotide sequence of a new tymovirus species infecting chiltepin, the wild ancestor of Capsicum annuum pepper crops, in Mexico was determined, and its host range has been explored. The genome of 6,517 nucleotides has the three open reading frames described for tymoviruses, putatively encoding an RNA-dependent RNA polymerase, a movement protein and a coat protein. The 5' and 3' untranslated regions have structures with typical signatures of the tymoviruses. Phylogenetic analyses revealed that this new virus is closely related to the other tymoviruses isolated from solanaceous plants. Its host range is mainly limited to solanaceous species, which notably include cultivated Capsicum species. In the latter, infection resulted in a severe reduction of growth, indicating the potential of this virus to be a significant crop pathogen. The name of chiltepin yellow mosaic virus (ChiYMV) is proposed for this new tymovirus.
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13
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Sperschneider J, Datta A. DotKnot: pseudoknot prediction using the probability dot plot under a refined energy model. Nucleic Acids Res 2010; 38:e103. [PMID: 20123730 PMCID: PMC2853144 DOI: 10.1093/nar/gkq021] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
RNA pseudoknots are functional structure elements with key roles in viral and cellular processes. Prediction of a pseudoknotted minimum free energy structure is an NP-complete problem. Practical algorithms for RNA structure prediction including restricted classes of pseudoknots suffer from high runtime and poor accuracy for longer sequences. A heuristic approach is to search for promising pseudoknot candidates in a sequence and verify those. Afterwards, the detected pseudoknots can be further analysed using bioinformatics or laboratory techniques. We present a novel pseudoknot detection method called DotKnot that extracts stem regions from the secondary structure probability dot plot and assembles pseudoknot candidates in a constructive fashion. We evaluate pseudoknot free energies using novel parameters, which have recently become available. We show that the conventional probability dot plot makes a wide class of pseudoknots including those with bulged stems manageable in an explicit fashion. The energy parameters now become the limiting factor in pseudoknot prediction. DotKnot is an efficient method for long sequences, which finds pseudoknots with higher accuracy compared to other known prediction algorithms. DotKnot is accessible as a web server at http://dotknot.csse.uwa.edu.au.
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Affiliation(s)
- Jana Sperschneider
- School of Computer Science and Software Engineering, The University of Western Australia, Perth, WA 6009, Australia.
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14
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Tzanetakis IE, Tsai CH, Martin RR, Dreher TW. A tymovirus with an atypical 3'-UTR illuminates the possibilities for 3'-UTR evolution. Virology 2009; 392:238-45. [PMID: 19664793 DOI: 10.1016/j.virol.2009.06.041] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Revised: 06/19/2009] [Accepted: 06/24/2009] [Indexed: 02/02/2023]
Abstract
We report the complete genome sequence of Dulcamara mottle virus (DuMV), confirming its membership within the Tymovirus genus, which was previously based on physical and pathology evidence. The 5'-untranslated region (UTR) and coding region of DuMV RNA have the typical characteristics of tymoviral RNAs. In contrast, the 3'-UTR is the longest and most unusual yet reported for a tymovirus, possessing an internal poly(A) tract, lacking a 3'-tRNA-like structure (TLS) and terminating at the 3'-end with -UUC instead of the typical -CC(A). An expressible cDNA clone was constructed and shown to be capable of producing infectious DuMV genomic RNAs with -UUC 3'-termini. A chimeric Turnip yellow mosaic virus (TYMV) genome bearing the DuMV 3'-UTR in place of the normal TLS was constructed in order to investigate the ability of the TYMV replication proteins to amplify RNAs with -UUC instead of -CC(A) 3'-termini. The chimeric genome was shown to be capable of replication and systemic spread in plants, although amplification was very limited. These experiments suggest the way in which DuMV may have evolved from a typical tymovirus, and illuminate the ways in which viral 3'-UTRs in general can evolve.
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15
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Shin HI, Tzanetakis IE, Dreher TW, Cho TJ. The 5′-UTR of Turnip yellow mosaic virus does not include a critical encapsidation signal. Virology 2009; 387:427-35. [DOI: 10.1016/j.virol.2009.02.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2008] [Revised: 01/19/2009] [Accepted: 02/04/2009] [Indexed: 10/21/2022]
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16
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Advances in RNA structure prediction from sequence: new tools for generating hypotheses about viral RNA structure-function relationships. J Virol 2009; 83:6326-34. [PMID: 19369331 DOI: 10.1128/jvi.00251-09] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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17
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Dreher TW. Role of tRNA-like structures in controlling plant virus replication. Virus Res 2008; 139:217-29. [PMID: 18638511 DOI: 10.1016/j.virusres.2008.06.010] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Revised: 06/14/2008] [Accepted: 06/16/2008] [Indexed: 10/21/2022]
Abstract
Transfer RNA-like structures (TLSs) that are sophisticated functional mimics of tRNAs are found at the 3'-termini of the genomes of a number of plant positive strand RNA viruses. Three natural aminoacylation identities are represented: valine, histidine, and tyrosine. Paralleling this variety in structure, the roles of TLSs vary widely between different viruses. For Turnip yellow mosaic virus, the TLS must be capable of valylation in order to support infectivity, major roles being the provision of translational enhancement and down-regulation of minus strand initiation. In contrast, valylation of the Peanut clump virus TLS is not essential. An intermediate situation seems to exist for Brome mosaic virus, whose RNAs 1 and 2, but not RNA 3, need to be capable of tyrosylation to support infectivity. Other known roles for certain TLSs include: (i) the recruitment of host CCA nucleotidyltransferase as a telomerase to maintain intact 3' CCA termini, (ii) involvement in the encapsidation of viral RNAs, and (iii) presentation of minus strand promoter elements for replicase recognition. In the latter role, the promoter elements reside within the TLS but are not functionally dependent on tRNA mimicry. The phylogenetic distribution of TLSs indicates that their evolutionary history includes frequent horizontal exchange, as has been observed for protein-coding regions of plant positive strand RNA viruses.
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Affiliation(s)
- Theo W Dreher
- Department of Microbiology and Center for Genome Research & Bioinformatics, 220 Nash Hall, Oregon State University, Corvallis, OR 97331, USA.
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18
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Segwagwe AT, Putnam ML, Druffel KL, Pappu HR, Eastwell KC. Molecular characterization of a new tymovirus from Diascia ornamental plants. Arch Virol 2008; 153:1495-503. [PMID: 18600295 DOI: 10.1007/s00705-008-0149-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2008] [Accepted: 05/21/2008] [Indexed: 10/21/2022]
Abstract
Two tymoviruses were identified in plants of Diascia x hybrida 'Sun Chimes Coral' that exhibited chlorotic mottling and reduced growth. A strain of Nemesia ring necrosis virus (NeRNV) designated NeRNV-WA was detected in symptomatic plants; the deduced amino acid sequence is virtually identical to that of the previously reported NeRNV-Nf from Nemesia fruticosa. Sequence analysis also revealed the presence of a new tymovirus, and the entire genomic sequence of this virus was determined. The genome of 6,290 nucleotides was organized into three potential open reading frames (ORFs) typical of viruses in the genus Tymovirus. Based on sequence identity to tymovirus sequences, ORFs I to III encoded the replicase, movement protein and coat protein, respectively. Amino acid sequence identities to those of NeRNV-Nf were 84.8, 50.3 and 94.8%, respectively. The 5'-untranslated region could potentially form four hairpin structures. Secondary structure analysis of the 3'-terminus showed that the RNA can form a transfer-RNA-like structure that has an anticodon specific for histidine. Only 77.9% nucleotide identity was found when complete genomic sequences of this tymovirus from diascia and NeRNV-Nf were compared. The name Diascia yellow mottle virus (DiaYMV) is proposed for this new tymovirus.
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Affiliation(s)
- A T Segwagwe
- Department of Crop Science and Production, Botswana College of Agriculture, Gaborone, Botswana
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Brierley I, Pennell S, Gilbert RJC. Viral RNA pseudoknots: versatile motifs in gene expression and replication. Nat Rev Microbiol 2007; 5:598-610. [PMID: 17632571 PMCID: PMC7096944 DOI: 10.1038/nrmicro1704] [Citation(s) in RCA: 139] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
RNA pseudoknots are structural motifs in RNA that are increasingly recognized in viral and cellular RNAs. They have been shown to have a various roles in virus and cellular gene expression. Pseudoknots are formed upon base pairing of a single-stranded region of RNA in the loop of a hairpin to a stretch of complementary nucleotides elsewhere in the RNA chain. This simple folding strategy can generate a large number of stable three-dimensional folds, which display a diverse range of highly specific functions. Pseudoknot function is frequently associated with interactions with ribosomes. The inclusion of pseudoknots in an mRNA can thus confer unusual translational properties. Many RNA viruses use pseudoknots in the control of viral RNA translation, replication and the switch between the two processes. Some satellite viruses encode ribozymes with active sites that are folded by a pseudoknot. In cellular RNAs, pseudoknots are associated with all aspects of mRNA function and also ribosome function, as ribosomal RNAs contain numerous pseudoknots. Other essential cellular pseudoknots have been described in telomerase RNA and transfer messenger RNA. Future research into pseudoknots will focus on structure–function relationships and bioinformatics identification of pseudoknots in genomes. The use of pseudoknots in antiviral applications could also become more widespread.
RNA pseudoknots have been identified in many different viral and cellular RNAs and are known to have various roles in virus and cellular gene expression. Here, Ian Brierley and colleagues review viral pseudoknots and the role of these structural motifs in virus gene expression and genome replication. RNA pseudoknots are structural elements found in almost all classes of RNA. First recognized in the genomes of plant viruses, they are now established as a widespread motif with diverse functions in various biological processes. This Review focuses on viral pseudoknots and their role in virus gene expression and genome replication. Although emphasis is placed on those well defined pseudoknots that are involved in unusual mechanisms of viral translational initiation and elongation, the broader roles of pseudoknots are also discussed, including comparisons with relevant cellular counterparts. The relationship between RNA pseudoknot structure and function is also addressed.
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Affiliation(s)
- Ian Brierley
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, CB2 1QP Cambridge UK
| | - Simon Pennell
- Division of Molecular Structure, National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA UK
| | - Robert J. C. Gilbert
- Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN UK
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Matsuda D, Dreher TW. Cap- and initiator tRNA-dependent initiation of TYMV polyprotein synthesis by ribosomes: evaluation of the Trojan horse model for TYMV RNA translation. RNA (NEW YORK, N.Y.) 2007; 13:129-37. [PMID: 17095542 PMCID: PMC1705754 DOI: 10.1261/rna.244407] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Turnip yellow mosaic virus (TYMV) RNA directs the translation of two overlapping open reading frames. Competing models have been previously published to explain ribosome access to the downstream polyprotein cistron. The Trojan horse model, based on cell-free experiments, proposes noncanonical cap-independent initiation in which the 3'-terminal tRNA-like structure (TLS) functionally replaces initiator tRNA, and the valine bound to the TLS becomes cis-incorporated into viral protein. The initiation coupling model, based on in vivo expression and ribosome toe-printing studies, proposes a variation of canonical leaky scanning. Here, we have re-examined the wheat germ extract experiments that led to the Trojan horse model, incorporating a variety of controls. We report that (1) translation in vitro from the polyprotein AUG of TYMV RNA is unchanged after removal of the 3' TLS but is stimulated by the presence of a 5'-cap; (2) the presence of free cap analog or edeine (which interferes with initiation at the ribosomal P site and its tRNA(i) (Met) involvement) inhibits translation from the polyprotein AUG; (3) the toe-prints of immediately post-initiation ribosomes on TYMV RNA are similar with and without an intact TLS; and (4) significant deacylation of valyl-TYMV RNA in wheat germ extract can complicate the detection of cis-incorporation. These results favor the initiation coupling model.
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Affiliation(s)
- Daiki Matsuda
- Department of Microbiology, Oregon State University, Corvallis, Oregon 97331-3804, USA
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Rudinger-Thirion J, Olsthoorn RCL, Giegé R, Barends S. Idiosyncratic behaviour of tRNA-like structures in translation of plant viral RNA genomes. J Mol Biol 2005; 355:873-8. [PMID: 16337653 DOI: 10.1016/j.jmb.2005.11.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2005] [Revised: 11/03/2005] [Accepted: 11/09/2005] [Indexed: 11/24/2022]
Abstract
Tobacco mosaic virus (TMV) and Nemesia ring necrosis virus (NeRNV) belong to the Tobamoviridae and Tymoviridae families, respectively. Although their RNAs present different 5'-untranslated regions and different family-specific genomic organizations, they share common 3'-ends organized into three consecutive pseudoknot structures followed by a histidylatable tRNA-like structure (TLS). We investigate here whether the histidine residue becomes incorporated into viral proteins and if the TLSs of TMV and NeRNV play a role in viral translation. Our results indicate that, regardless of the genomic context, the histidine moiety does not become incorporated in proteins via ribosomal translation, and that disruption of the TLS in either viral RNA does not perturb the viral translation patterns. In the light of the present data and of previous results on tymoviral TLSVal and bromoviral TLSTyr showing differential effects on translation, we suggest that the key role for the TLS in promoting translation initiation appears to be dictated by the TLS architecture and identity.
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Affiliation(s)
- Joëlle Rudinger-Thirion
- Institut de Biologie Moléculaire et Cellulaire du CNRS, UPR 9002, Université Louis Pasteur, 15 rue René Descartes, F-67084 Strasbourg Cedex, France
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Koenig R, Pleij CWA, Lesemann DE, Loss S, Vetten HJ. Molecular characterization of isolates of anagyris vein yellowing virus, plantago mottle virus and scrophularia mottle virus – comparison of various approaches for tymovirus classification. Arch Virol 2005; 150:2325-38. [PMID: 15883655 DOI: 10.1007/s00705-005-0545-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2005] [Accepted: 03/08/2005] [Indexed: 11/30/2022]
Abstract
The complete nucleotide sequences were determined for the genomic RNAs of three tymoviruses, i.e. isolates of anagyris vein yellowing virus (AVYV), plantago mottle virus (PlMoV) and scrophularia mottle virus (SrMV) which are all serologically closely related to ononis yellow mosaic virus (ibid) and to Nemesia ring necrosis virus (NeRNV), a recently described recombinant virus which is widely spread in commercially grown ornamental plant species belonging to the Scrophulariaceae. Total nucleotide and coat protein amino acid sequence identities revealed similar groupings in the genus tymovirus as serological studies did. The latter, however, tended to suggest much closer relationships than the molecular data and may fail to recognise the distinctiveness of new tymovirus species. The usefulness of various species demarcation criteria for the classification of tymoviruses is discussed.
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Affiliation(s)
- R Koenig
- Biologische Bundesanstalt für Land- und Forstwirtschaft, Institut für Pflanzenvirologie, Mikrobiologie und Biologische Sicherheit, Braunschweig, Germany.
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