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From Contagium vivum fluidum to Riboviria: A Tobacco Mosaic Virus-Centric History of Virus Taxonomy. Biomolecules 2022; 12:biom12101363. [PMID: 36291572 PMCID: PMC9599303 DOI: 10.3390/biom12101363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 09/12/2022] [Accepted: 09/19/2022] [Indexed: 11/17/2022] Open
Abstract
Viruses were discovered as agents of disease in the late 19th century, but it was not until the 1930s that the nature of these agents was elucidated. Nevertheless, as soon as viral diseases started to be recognized and cataloged, there were attempts to classify and name viruses. Although these early attempts failed to be adopted by the nascent virology community, they are evidence of the human compulsion to try to organize the natural world into well-defined categories. Different classification schemes were proposed during the 20th century, but again none were widely embraced by virologists. In 1966, with the creation of the International Committee on Nomenclature of Viruses (eventually renamed as the International Committee on Taxonomy of Viruses), a more organized effort led to an official taxonomy in which viruses were classified into families and genera. At present, a much better understanding of the evolutionary relationships among viruses has led to the establishment of a 15-rank taxonomy based primarily on these evolutionary relationships. This review of virus taxonomy will be centered on the tobacco mosaic virus (TMV), the agent of the disease studied by Dmitry Ivanovsky and the first virus to be recognized as such, which was often historically at the center of major advancements in virology during the 20th century.
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Liu S, Xu T, Wang C, Jia T, Zhang Q. A Novel Picornavirus Discovered in White Leg Shrimp Penaeus vannamei. Viruses 2021; 13:v13122381. [PMID: 34960649 PMCID: PMC8706678 DOI: 10.3390/v13122381] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Revised: 11/20/2021] [Accepted: 11/23/2021] [Indexed: 11/19/2022] Open
Abstract
Global shrimp farming is increasingly threatened by various emerging viruses. In the present study, a novel picornavirus, Penaeus vannamei picornavirus (PvPV), was discovered in moribund White leg shrimp (Penaeus vannamei) collected from farm ponds in China in 2015. Similar to most picornaviruses, PvPV is non-enveloped RNA virus, with a particle diameter of approximately 30 nm. The sequence of the positive single-stranded RNA genome with a length of 10,550 nts was characterized by using genome sequencing and reverse transcription PCR. The existence of PvPV related proteins was further proved by confirmation of viral amino acid sequences, using mass spectrometry analysis. Phylogenetic analysis based on the full-length genomic sequence revealed that PvPV was more closely related to the Wenzhou shrimp virus 8 than to any other dicistroviruses in the order Picornavirales. Genomic sequence conservative domain prediction analysis showed that the PvPV genome encoded a large tegument protein UL36, which was unique among the known dicistroviruses and different from other dicistroviruses. According to these molecular features, we proposed that PvPV is a new species in the family Dicistroviridae. This study reported the first whole-genome sequence of a novel and distinct picornavirus in crustaceans, PvPV, and suggests that further studies of PvPV would be helpful in understanding its evolution and potential pathogenicity, as well as in developing diagnostic techniques.
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Affiliation(s)
- Shuang Liu
- Qingdao Key Laboratory of Mariculture Epidemiology and Biosecurity, Key Laboratory of Maricultural Organism Disease Control, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China; (S.L.); (T.X.); (C.W.); (T.J.)
| | - Tingting Xu
- Qingdao Key Laboratory of Mariculture Epidemiology and Biosecurity, Key Laboratory of Maricultural Organism Disease Control, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China; (S.L.); (T.X.); (C.W.); (T.J.)
| | - Chong Wang
- Qingdao Key Laboratory of Mariculture Epidemiology and Biosecurity, Key Laboratory of Maricultural Organism Disease Control, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China; (S.L.); (T.X.); (C.W.); (T.J.)
| | - Tianchang Jia
- Qingdao Key Laboratory of Mariculture Epidemiology and Biosecurity, Key Laboratory of Maricultural Organism Disease Control, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China; (S.L.); (T.X.); (C.W.); (T.J.)
| | - Qingli Zhang
- Qingdao Key Laboratory of Mariculture Epidemiology and Biosecurity, Key Laboratory of Maricultural Organism Disease Control, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China; (S.L.); (T.X.); (C.W.); (T.J.)
- Laboratory for Marine Fisheries Science and Food Production Processes, Pilot National Laboratory for Marine Science and Technology, Qingdao 266071, China
- Correspondence: ; Tel.: +86-532-8582-3062 (ext. 812)
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Abstract
The discovery of a new class of pathogen, viruses, in the late 19th century, ushered in a period of study of the biochemical and structural properties of these entities in which plant viruses played a prominent role. This was, in large part, due to the relative ease with which sufficient quantities of material could be produced for such analyses. As analytical techniques became increasingly sensitive, similar studies could be performed on the viruses from other organisms. However, plant viruses continued to play an important role in the development of molecular biology, including the demonstration that RNA can be infectious, the determination of the genetic code, the mechanism by which viral RNAs are translated, and some of the early studies on gene silencing. Thus, the study of plant viruses should not be considered a "niche" subject but rather part of the mainstream of virology and molecular biology.
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Dolja VV, Koonin EV. Common origins and host-dependent diversity of plant and animal viromes. Curr Opin Virol 2012; 1:322-31. [PMID: 22408703 DOI: 10.1016/j.coviro.2011.09.007] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Many viruses infecting animals and plants share common cores of homologous genes involved in the key processes of viral replication. In contrast, genes that mediate virus–host interactions including in many cases capsid protein (CP) genes are markedly different. There are three distinct scenarios for the origin of related viruses of plants and animals: first, evolution from a common ancestral virus predating the divergence of plants and animals; second, horizontal transfer of viruses, for example, through insect vectors; third, parallel origin from related genetic elements. We present evidence that each of these scenarios contributed, to a varying extent, to the evolution of different groups of viruses.
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Affiliation(s)
- Valerian V Dolja
- Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR 97331, USA
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Gibbs AJ, Torronen M, Mackenzie AM, Wood JT, Armstrong JS, Kondo H, Tamada T, Keese PL. The enigmatic genome of Chara australis virus. J Gen Virol 2011; 92:2679-2690. [PMID: 21733884 DOI: 10.1099/vir.0.033852-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Most of the genomic sequence of Chara australis virus (CAV), previously called Chara corallina virus, has been determined. It is a ssRNA molecule of 9065 nt with at least four ORFs. At its 5' end is an ORF encoding a protein of 227 kDa, distantly homologous to the multifunctional replicases of benyviruses and rubiviruses. Next is an ORF encoding a protein of 44 kDa, homologous to the helicases of pestiviruses. The third ORF encodes an unmatched protein of 38 kDa that is probably a movement protein. The fourth and 3'-terminal ORF encodes a protein of 17.7 kDa homologous to the coat proteins of tobamoviruses. The short methyltransferase region of the CAV replicase matches only the C-terminal motif of benyvirus methyltransferases. This and other clues indicate that approximately 11% and 2% of the 5' and 3' termini of the complete CAV genome, respectively, are missing from the sequence. The aligned amino acid sequences of the CAV proteins and their nearest homologues contain many gaps but relationships inferred from them were little affected by removal of these gaps. Sequence comparisons show that three of the CAV genes may have diverged from the most closely related genes of other viruses 250-450 million years ago, and the sister relationship between the genes of CAV and those of benyviruses and tobamoviruses, mirroring the ancient sister relationship between charophytes (i.e. the algal host of CAV) and embryophytes (i.e. the plant hosts of tobamoviruses and benyviruses), is congruent with this possibility.
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Affiliation(s)
- Adrian J Gibbs
- Research School of Biological Science, Australian National University, Canberra, ACT 0200, Australia
| | - Marjo Torronen
- Research School of Biological Science, Australian National University, Canberra, ACT 0200, Australia
| | - Anne M Mackenzie
- Research School of Biological Science, Australian National University, Canberra, ACT 0200, Australia
| | - Jeffery T Wood
- Research School of Biological Science, Australian National University, Canberra, ACT 0200, Australia
| | - John S Armstrong
- Research School of Biological Science, Australian National University, Canberra, ACT 0200, Australia
| | - Hideki Kondo
- Research School of Biological Science, Australian National University, Canberra, ACT 0200, Australia
| | - Tetsuo Tamada
- Research School of Biological Science, Australian National University, Canberra, ACT 0200, Australia
| | - Paul L Keese
- Research School of Biological Science, Australian National University, Canberra, ACT 0200, Australia
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Batuman O, Kuo YW, Palmieri M, Rojas MR, Gilbertson RL. Tomato chocolate spot virus, a member of a new torradovirus species that causes a necrosis-associated disease of tomato in Guatemala. Arch Virol 2010; 155:857-69. [PMID: 20376682 PMCID: PMC2880234 DOI: 10.1007/s00705-010-0653-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Accepted: 02/28/2010] [Indexed: 11/25/2022]
Abstract
Tomatoes in Guatemala have been affected by a new disease, locally known as "mancha de chocolate" (chocolate spot). The disease is characterized by distinct necrotic spots on leaves, stems and petioles that eventually expand and cause a dieback of apical tissues. Samples from symptomatic plants tested negative for infection by tomato spotted wilt virus, tobacco streak virus, tobacco etch virus and other known tomato-infecting viruses. A virus-like agent was sap-transmitted from diseased tissue to Nicotiana benthamiana and, when graft-transmitted to tomato, this agent induced chocolate spot symptoms. This virus-like agent also was sap-transmitted to Datura stramonium and Nicotiana glutinosa, but not to a range of non-solanaceous indicator plants. Icosahedral virions approximately 28-30 nm in diameter were purified from symptomatic N. benthamiana plants. When rub-inoculated onto leaves of N. benthamiana plants, these virions induced symptoms indistinguishable from those in N. benthamiana plants infected with the sap-transmissible virus associated with chocolate spot disease. Tomatoes inoculated with sap or grafted with shoots from N. benthamiana plants infected with purified virions developed typical chocolate spot symptoms, consistent with this virus being the causal agent of the disease. Analysis of nucleic acids associated with purified virions of the chocolate-spot-associated virus, revealed a genome composed of two single-stranded RNAs of approximately 7.5 and approximately 5.1 kb. Sequence analysis of these RNAs revealed a genome organization similar to recently described torradoviruses, a new group of picorna-like viruses causing necrosis-associated diseases of tomatoes in Europe [tomato torrado virus (ToTV)] and Mexico [tomato apex necrosis virus (ToANV) and tomato marchitez virus (ToMarV)]. Thus, the approximately 7.5 kb and approximately 5.1 kb RNAs of the chocolate-spot-associated virus corresponded to the torradovirus RNA1 and RNA2, respectively; however, sequence comparisons revealed 64-83% identities with RNA1 and RNA2 sequences of ToTV, ToANV and ToMarV. Together, these results indicate that the chocolate-spot-associated virus is a member of a distinct torradovirus species and, thus, another member of the recently established genus Torradovirus in the family Secoviridae. The name tomato chocolate spot virus is proposed.
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Affiliation(s)
- O. Batuman
- Department of Plant Pathology, University of California Davis, Davis, CA 95616 USA
| | - Y.-W. Kuo
- Department of Plant Pathology, University of California Davis, Davis, CA 95616 USA
| | - M. Palmieri
- Department of Plant Protection, University of Valle de Guatemala, Guatemala City, Republic of Guatemala
| | - M. R. Rojas
- Department of Plant Pathology, University of California Davis, Davis, CA 95616 USA
| | - R. L. Gilbertson
- Department of Plant Pathology, University of California Davis, Davis, CA 95616 USA
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Sainsbury F, Cañizares MC, Lomonossoff GP. Cowpea mosaic virus: the plant virus-based biotechnology workhorse. ANNUAL REVIEW OF PHYTOPATHOLOGY 2010; 48:437-55. [PMID: 20455698 DOI: 10.1146/annurev-phyto-073009-114242] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
In the 50 years since it was first described, Cowpea mosaic virus (CPMV) has become one of the most intensely studied plant viruses. Research in the past 15 to 20 years has shifted from studying the underlying genetics and structure of the virus to focusing on ways in which it can be exploited in biotechnology. This work led first to the use of virus particles to present peptides, then to the creation of a variety of replicating virus vectors and finally to the development of a highly efficient protein expression system that does not require viral replication. The circle has been completed by the use of the latter system to create empty particles for peptide presentation and other novel uses. The history of CPMV in biotechnology can be likened to an Ouroborus, an ancient symbol depicting a snake or dragon swallowing its own tail, thus forming a circle.
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Affiliation(s)
- Frank Sainsbury
- Department of Biological Chemistry, John Innes Centre, Norwich NR4 7UH,United Kingdom.
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8
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Characterization of the virus encoded subunit of turnip yellow mosaic virus RNA replicase. Virology 2008; 152:322-30. [PMID: 18640642 DOI: 10.1016/0042-6822(86)90135-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/1985] [Accepted: 03/12/1986] [Indexed: 11/23/2022]
Abstract
An antiserum raised against TYMV-RNA encoded protein P115 partially inhibits TYMV RNA replicase activity, demonstrating that this protein is involved in TYMV RNA synthesis. The detection of protein P115 by an antibody linked polymerase assay demonstrates that protein P115 is indeed a subunit of the TYMV RNA replicase, the enzyme known to synthesize viral RNA in infected Chinese cabbage. The use of translation products of other tymoviruses indicates that the serological relationship between the virus-encoded replicase subunits of these viruses and protein P115 is very weak at the best.
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9
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Huisman MJ, Sarachu AN, Alblas F, Bol JF. Alfalfa mosaic virus temperature-sensitive mutants. II. Early functions encoded by RNAs 1 and 2. Virology 2008; 141:23-9. [PMID: 18639839 DOI: 10.1016/0042-6822(85)90179-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/1984] [Accepted: 10/06/1984] [Indexed: 11/19/2022]
Abstract
Mutants Bts 03 and Mts 04 of alfalfa mosaic virus (AIMV) have temperature-sensitive mutations in genomic RNAs 1 and 2, respectively. These mutants are defective in the production of viral minus-strand RNA, coat protein, and infectious virus when assayed in cowpea protoplasts at the nonpermissive temperature (30 degrees). To determine the temperature-sensitive step in the replication cycle, mutant-infected protoplasts were shifted from an incubation temperature of 25 degrees (permissive temperature) to 30 degrees at different times during a 24-hr incubation period. For both mutants an initial incubation of infected protoplasts for 6 hr at 25 degrees was sufficient to permit a normal minus-strand RNA synthesis, translation of RNA 4 into coat protein, and assembly of infectious virus during the subsequent incubation at the nonpermissive temperature. Probably, AIMV RNAs 1 and 2 encoded proteins are produced early in infection and the mutant proteins are protected from inactivation at 30 degrees once they are incorporated in a functional structure.
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Affiliation(s)
- M J Huisman
- Department of Biochemistry, State University of Leiden, P.O. Box 9505, 2300 RA Leiden, The Netherlands
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10
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Le Gall O, Christian P, Fauquet CM, King AMQ, Knowles NJ, Nakashima N, Stanway G, Gorbalenya AE. Picornavirales, a proposed order of positive-sense single-stranded RNA viruses with a pseudo-T = 3 virion architecture. Arch Virol 2008; 153:715-27. [DOI: 10.1007/s00705-008-0041-x] [Citation(s) in RCA: 214] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2007] [Accepted: 11/19/2007] [Indexed: 01/14/2023]
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11
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Tang WF, Yang SY, Wu BW, Jheng JR, Chen YL, Shih CH, Lin KH, Lai HC, Tang P, Horng JT. Reticulon 3 binds the 2C protein of enterovirus 71 and is required for viral replication. J Biol Chem 2006; 282:5888-98. [PMID: 17182608 DOI: 10.1074/jbc.m611145200] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Enterovirus 71 is an enterovirus of the family Picornaviridae. The 2C protein of poliovirus, a relative of enterovirus 71, is essential for viral replication. The poliovirus 2C protein is associated with host membrane vesicles, which form viral replication complexes where viral RNA synthesis takes place. We have now identified a host-encoded 2C binding protein called reticulon 3, which we found to be associated with the replication complex through direct interaction with the enterovirus 71-encoded 2C protein. We observed that the N terminus of the 2C protein, which has both RNA- and membrane-binding activity, interacted with reticulon 3. This region of interaction was mapped to its reticulon homology domain, whereas that of 2C was encoded by the 25th amino acid, isoleucine. Reticulon 3 could also interact with the 2C proteins encoded by other enteroviruses, such as poliovirus and coxsackievirus A16, implying that it is a common factor for such viral replication. Reduced production of reticulon 3 by RNA interference markedly reduced the synthesis of enterovirus 71-encoded viral proteins and replicative double-stranded RNA, reducing plaque formation and apoptosis. Furthermore, reintroduction of nondegradable reticulon 3 into these knockdown cells rescued enterovirus 71 infectivity, and viral protein and double-stranded RNA synthesis. Thus, reticulon 3 is an important component of enterovirus 71 replication, through its potential role in modulation of the sequential interactions between enterovirus 71 viral RNA and the replication complex.
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Affiliation(s)
- Wen-Fang Tang
- Department of Biochemistry and Chang Gung Bioinformatics Center, Chang Gung University, Kweishan, Taoyuan 333, Taiwan
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12
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Affiliation(s)
- Tianwei Lin
- Department of Molecular Biology, Center for Integrative Molecular Biosciences, Scripps Research Institute, La Jolla, California 92037, USA
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Carette JE, Gühl K, Wellink J, Van Kammen A. Coalescence of the sites of cowpea mosaic virus RNA replication into a cytopathic structure. J Virol 2002; 76:6235-43. [PMID: 12021357 PMCID: PMC136224 DOI: 10.1128/jvi.76.12.6235-6243.2002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cowpea mosaic virus (CPMV) replication induces an extensive proliferation of endoplasmic reticulum (ER) membranes, leading to the formation of small membranous vesicles where viral RNA replication takes place. Using fluorescent in situ hybridization, we found that early in the infection of cowpea protoplasts, CPMV plus-strand RNA accumulates at numerous distinct subcellular sites distributed randomly throughout the cytoplasm which rapidly coalesce into a large body located in the center of the cell, often near the nucleus. The combined use of immunostaining and a green fluorescent protein ER marker revealed that during the course of an infection, CPMV RNA colocalizes with the 110-kDa viral polymerase and other replication proteins and is always found in close association with proliferated ER membranes, indicating that these sites correspond to the membranous site of viral replication. Experiments with the cytoskeleton inhibitors oryzalin and latrunculin B point to a role of actin and not tubulin in establishing the large central structure. The induction of ER membrane proliferations in CPMV-infected protoplasts did not coincide with increased levels of BiP mRNA, indicating that the unfolded-protein response is not involved in this process.
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Affiliation(s)
- Jan E Carette
- Laboratory of Molecular Biology, Wageningen University, 6703 HA Wageningen, The Netherlands
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Carette JE, Verver J, Martens J, van Kampen T, Wellink J, van Kammen A. Characterization of plant proteins that interact with cowpea mosaic virus '60K' protein in the yeast two-hybrid system. J Gen Virol 2002; 83:885-893. [PMID: 11907339 DOI: 10.1099/0022-1317-83-4-885] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cowpea mosaic virus (CPMV) replication occurs in close association with small membranous vesicles in the host cell. The CPMV RNA1-encoded 60 kDa nucleotide-binding protein ('60K') plays a role in the formation of these vesicles. In this study, five cellular proteins were identified that interacted with different domains of 60K using a yeast two-hybrid search of an Arabidopsis cDNA library. Two of these host proteins (termed VAP27-1 and VAP27-2), with high homology to the VAP33 family of SNARE-like proteins from animals, interacted specifically with the C-terminal domain of 60K and upon transient expression colocalized with 60K in CPMV-infected cowpea protoplasts. eEF1-beta, picked up using the central domain of 60K, was also found to colocalize with 60K. The possible role of these host proteins in the viral replicative cycle is discussed.
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Affiliation(s)
- Jan E Carette
- Laboratory of Molecular Biology, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands1
| | - Jan Verver
- Laboratory of Molecular Biology, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands1
| | - Joost Martens
- Laboratory of Molecular Biology, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands1
| | - Tony van Kampen
- Laboratory of Molecular Biology, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands1
| | - Joan Wellink
- Laboratory of Molecular Biology, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands1
| | - Ab van Kammen
- Laboratory of Molecular Biology, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands1
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Drygin YF, Sapotsky MV, Bogdanov AA. Radish mosaic virus VPg Characteristics and linkage with virion RNAs. FEBS Lett 2001. [DOI: 10.1016/0014-5793(87)80155-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Carette JE, Stuiver M, Van Lent J, Wellink J, Van Kammen A. Cowpea mosaic virus infection induces a massive proliferation of endoplasmic reticulum but not Golgi membranes and is dependent on de novo membrane synthesis. J Virol 2000; 74:6556-63. [PMID: 10864669 PMCID: PMC112165 DOI: 10.1128/jvi.74.14.6556-6563.2000] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/1999] [Accepted: 04/17/2000] [Indexed: 11/20/2022] Open
Abstract
Replication of cowpea mosaic virus (CPMV) is associated with small membranous vesicles that are induced upon infection. The effect of CPMV replication on the morphology and distribution of the endomembrane system in living plant cells was studied by expressing green fluorescent protein (GFP) targeted to the endoplasmic reticulum (ER) and the Golgi membranes. CPMV infection was found to induce an extensive proliferation of the ER, whereas the distribution and morphology of the Golgi stacks remained unaffected. Immunolocalization experiments using fluorescence confocal microscopy showed that the proliferated ER membranes were closely associated with the electron-dense structures that contain the replicative proteins encoded by RNA1. Replication of CPMV was strongly inhibited by cerulenin, an inhibitor of de novo lipid synthesis, at concentrations where the replication of the two unrelated viruses alfalfa mosaic virus and tobacco mosaic virus was largely unaffected. These results suggest that proliferating ER membranes produce the membranous vesicles formed during CPMV infection and that this process requires continuous lipid biosynthesis.
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Affiliation(s)
- J E Carette
- Laboratory of Molecular Biology, Wageningen University, 6703 HA Wageningen, The Netherlands
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Lin T, Chen Z, Usha R, Stauffacher CV, Dai JB, Schmidt T, Johnson JE. The refined crystal structure of cowpea mosaic virus at 2.8 A resolution. Virology 1999; 265:20-34. [PMID: 10603314 DOI: 10.1006/viro.1999.0038] [Citation(s) in RCA: 225] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Comoviruses are a group of plant viruses in the picornavirus superfamily. The type member of comoviruses, cowpea mosaic virus (CPMV), was crystallized in the cubic space group I23, a = 317 A and the hexagonal space group P6(1)22, a = 451 A, c = 1038 A. Structures of three closely similar nucleoprotein particles were determined in the cubic form. The roughly 300-A capsid was similar to the picornavirus capsid displaying a pseudo T = 3 (P = 3) surface lattice. The three beta-sandwich domains adopt two orientations, one with the long axis radial and the other two with the long axes tangential in reference to the capsid sphere. T = 3 viruses display one or the other of these two orientations. The CPMV capsid was permeable to cesium ions, leading to a disturbance of the beta-annulus inside a channel-like structure, suggesting an ion channel. The hexagonal crystal form diffracted X rays to 3 A resolution, despite the large unit cell. The large ( approximately 200 A) solvent channels in the lattice allow exchange of CPMV cognate Fab fragments. As an initial step in the structure determination of the CPMV/Fab complex, the P6(1)22 crystal structure was solved by molecular replacement with the CPMV model determined in the cubic cell.
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Affiliation(s)
- T Lin
- Department of Molecular Biology, MB-31, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California, 92037, USA
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Prüfer D, Kawchuk L, Monecke2 M, Nowok S, Fischer R, Rohde W. Immunological analysis of potato leafroll luteovirus (PLRV) P1 expression identifies a 25 kDa RNA-binding protein derived via P1 processing. Nucleic Acids Res 1999; 27:421-5. [PMID: 9862960 PMCID: PMC148195 DOI: 10.1093/nar/27.2.421] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mono- and polyclonal antibodies directed against different domains of the potato leafroll luteovirus (PLRV) P1 (ORF1) protein were applied to the analysis of P1 expression during PLRV replication in planta. Western analyses detected P1 and a protein of approximately 25 kDa (P1-C25) that accumulated to readily detectable amounts in PLRV-infected plants, but was not detected by in vitro cell-free translation of P1. P1-C25 represents the C-terminus of P1 and is a proteolytic cleavage product produced during P1 processing. On the basis of its molecular weight, the N-terminus of P1-C25 is either identical to or located adjacent to the previously identified PLRV genome-linked protein, VPg. P1-C25 is not associated with virus particles, and subcellular localization experiments detected P1-C25, but not P1, in the membrane and cytoplasmic fractions of PLRV-infected cells. In addition, P1-C25 exhibits nucleic acid-binding properties. On the basis of its biosynthesis, localization and biochemical properties, P1-C25 may facilitate the formation of P1/PLRV RNA complexes in which the spatial proximity allows for covalent bond formation between PLRV RNA and VPg.
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Affiliation(s)
- D Prüfer
- Max-Planck-Institut für Züchtungsforschung, Carl-von-Linné Weg 10, 50829 Köln, Germany.
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20
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Haydon D, Lea S, Fry L, Knowles N, Samuel AR, Stuart D, Woolhouse ME. Characterizing sequence variation in the VP1 capsid proteins of foot and mouth disease virus (serotype 0) with respect to virion structure. J Mol Evol 1998; 46:465-75. [PMID: 9541542 DOI: 10.1007/pl00006327] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The VP1 capsid protein of foot and mouth disease virus (FMDV) is highly polymorphic and contains several of the major immunogenic sites important to effective antibody neutralization and subsequent viral clearance by the immune system. Whether this high level of polymorphism is of adaptive value to the virus remains unknown. In this study we examined sequence data from a set of 55 isolates in order to establish the nature of selective pressures acting on this gene. Using the known molecular structure of VP1, the rates and ratios of different types of nonsynonymous and synonymous changes were compared between different parts of the protein. All parts of the protein are subject to purifying selection, but this is greatest amongst those amino acid residues within beta-strands and is significantly reduced at residues exposed on the capsid surface, which include those residues demonstrated by previous mutational analyses to permit the virus to escape from monoclonal antibody binding. The ratios of nonsynonymous substitution resulting in various forms of physicochemically radical and conserved amino acid change were shown to be largely equal throughout these different parts of the protein. There was a consistently higher level of nonsynonymous and charge radical sites in those regions of the gene coding for residues exposed on the outer surface of the capsid and a marked difference in the use of amino acids between surface and nonsurface regions of the protein. However, the analysis is consistent with the hypothesis that the observed sequence variation arises where it is least likely to be disruptive to the higher-order structure of the protein and is not necessarily due to positive Darwinian selection.
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Affiliation(s)
- D Haydon
- Pirbright Laboratory, Institute for Animal Health, Woking, United Kingdom.
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21
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Gorbalenya AE, Snijder EJ. Viral cysteine proteinases. PERSPECTIVES IN DRUG DISCOVERY AND DESIGN : PD3 1996; 6:64-86. [PMID: 32288276 PMCID: PMC7104566 DOI: 10.1007/bf02174046] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/11/1996] [Accepted: 06/13/1996] [Indexed: 11/26/2022]
Abstract
Dozens of novel cysteine proteinases have been identified in positive single-stranded RNA viruses and, for the first time, in large double-stranded DNA viruses. The majority of these proteins are distantly related to papain or chymotrypsin and may be direct descendants of primordial proteolytic enzymes. Virus genome synthesis and expression, virion formation, virion entry into the host cell, as well as cellular architecture and functioning can be under the control of viral cysteine proteinases during infection. RNA virus proteinases mediate their liberation from giant multidomain precursors in which they tend to occupy conserved positions. These proteinases possess a narrow substrate specificity, can cleave in cis and in trans, and may also have additional, nonproteolytic functions. The mechanisms of catalysis, substrate recognition and RNA binding were highlighted by the recent analysis of the three-dimensional structure of the chymotrypsin-like cysteine proteinases of two RNA viruses.
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Affiliation(s)
- Alexander E Gorbalenya
- 1M.P. Chumakov Institute of Poliomyelitis and Viral Encephalitides, Russian Academy of Medical Sciences, 142782 Moscow Region
- 2A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119899 Moscow, Russia
| | - Eric J Snijder
- 3Department of Virology, Institute of Medical Microbiology, Leiden University, P.O. Box 9600, 2300 RC Leiden, The Netherlands
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22
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Roth DA, He X. Viral-dependent phosphorylation of a dsRNA-dependent kinase. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 1994; 14:28-47. [PMID: 7914805 DOI: 10.1007/978-3-642-78549-8_3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- D A Roth
- Dept. Plant, Soil and Insect Sciences, University of Wyoming, Laramie 82071
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23
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Wellink J, van Bokhoven H, Le Gall O, Verver J, van Kammen A. Replication and translation of cowpea mosaic virus RNAs are tightly linked. ARCHIVES OF VIROLOGY. SUPPLEMENTUM 1994; 9:381-92. [PMID: 8032269 DOI: 10.1007/978-3-7091-9326-6_38] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The genome of cowpea mosaic virus (CPMV) is divided among two positive strand RNA molecules. B-RNA is able to replicate independently from M-RNA in cowpea protoplasts. Replication of mutant B-transcripts could not be supported by co-inoculated wild-type B-RNA, indicating that B-RNA cannot be efficiently replicated in trans. Hence replication of a B-RNA molecule is tightly linked to its translation and/or at least one of the replicative proteins functions in cis only. Remarkably also for efficient replication of M-RNA one of its translation products was found to be required in cis. This 58K protein possibly helps in directing the B-RNA-encoded replication complex to the M-RNA. In order to identify the viral polymerase the CPMV B-RNA-specific proteins have been produced individually in cowpea protoplasts using CaMV 35S promoter based expression vectors. Only protoplasts transfected with a vector containing the 200K coding sequence were able to support replication of co-transfected M-RNA. Despite this, CPMV-specific RNA polymerase activity could not be detected in extracts of these protoplasts using a poly(A)/oligo(U) assay. These results indicate that, in contrast to the poliovirus polymerase, the CPMV polymerase is not able to accept oligo(U) as a primer and in addition support the concept that translation and replication are linked.
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Affiliation(s)
- J Wellink
- Department of Molecular Biology, Agricultural University, Wageningen, The Netherlands
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24
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Abstract
The current consensus view is that a higher hierarchical taxonomy of viruses cannot be established for two reasons. Firstly, viruses appear to be polyphyletic in origin, with several sets of viruses arising by different, independent routes at different times. Secondly, subsequent virus adaptation for survival in different host/vector combinations has involved the selective acquisition of additional genes by a process of cassette or modular evolution, with these additional gene modules coming from other viruses or host genetic material. Thus, depending on the gene product used for comparison, different phylogenetic relationships can be deduced. Further virus adaptation can arise by reassortment of segmented genomes, gene duplication, deletions, frameshift mutations, point mutations or de novo development of new gene products from existing, unused reading frames. The solution to the first objection is to place all viruses in a separate kingdom and assign the current viruses to several phyla that reflect these diverse origins. The solution to the second objection is to consider the core module of replication machinery as the major criterion on which to make the initial assignments to classes and orders. For RNA viruses, the major criterion is the sequence identity of the RNA-dependent RNA polymerase. Using this criterion, the positive strand RNA viruses can be assigned to five classes that correspond to the recently recognized supergroups of RNA viruses. These five classes contain four, three, three, three and one order(s) respectively. These fourteen orders contain 31 virus families (including 17 families of plant viruses) and 48 genera (including 30 genera of plant viruses). This approach confirms the separation of the alphaviruses and flaviviruses into two families, the Togaviridae and Flaviridae, but suggests that several other current taxonomic assignments, such as the pestiviruses, hepatitis C virus, rubiviruses, hepatitis E virus and arteriviruses, may be wrong. The coronaviruses and toroviruses appear to be distinct families in distinct orders, not distinct genera of the same family as currently classified. In addition, the luteoviruses are split into two families and apple chlorotic leaf spot virus appears not to be a closterovirus but a new genus of the Potexviridae. From an analysis of the polymerase dendrograms of the dsRNA viruses, it appears that they are not closely related to each other, but belong to four additional classes (Partitiviridae, Reoviridae, Birnaviridae and Cystoviridae) and one additional order (Totiviridae) of one of the classes of positive ssRNA viruses in the same subphylum as the positive strand RNA viruses.(ABSTRACT TRUNCATED AT 400 WORDS)
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Key Words
- virus, taxonomy, hierarchy
- dna viruses, rna viruses
- review
- dsdna, double-stranded dna
- dsrna, double-stranded rna
- icnv, international committee on nomenclature of viruses
- ictv, international committee for taxonomy of viruses
- kb, kilobase
- kbp, kilobase pair
- orf, open reading frame
- ssdna, single-stranded dna
- ssrna, single-stranded rna
- taxonomie, virus, hiérarchie
- virus adn, virus arn
- revue
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Affiliation(s)
- C W Ward
- CSIRO, Division of Biomolecular Engineering, Parkville, Victoria, Australia
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25
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Koonin EV, Dolja VV. Evolution and taxonomy of positive-strand RNA viruses: implications of comparative analysis of amino acid sequences. Crit Rev Biochem Mol Biol 1993; 28:375-430. [PMID: 8269709 DOI: 10.3109/10409239309078440] [Citation(s) in RCA: 714] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Despite the rapid mutational change that is typical of positive-strand RNA viruses, enzymes mediating the replication and expression of virus genomes contain arrays of conserved sequence motifs. Proteins with such motifs include RNA-dependent RNA polymerase, putative RNA helicase, chymotrypsin-like and papain-like proteases, and methyltransferases. The genes for these proteins form partially conserved modules in large subsets of viruses. A concept of the virus genome as a relatively evolutionarily stable "core" of housekeeping genes accompanied by a much more flexible "shell" consisting mostly of genes coding for virion components and various accessory proteins is discussed. Shuffling of the "shell" genes including genome reorganization and recombination between remote groups of viruses is considered to be one of the major factors of virus evolution. Multiple alignments for the conserved viral proteins were constructed and used to generate the respective phylogenetic trees. Based primarily on the tentative phylogeny for the RNA-dependent RNA polymerase, which is the only universally conserved protein of positive-strand RNA viruses, three large classes of viruses, each consisting of distinct smaller divisions, were delineated. A strong correlation was observed between this grouping and the tentative phylogenies for the other conserved proteins as well as the arrangement of genes encoding these proteins in the virus genome. A comparable correlation with the polymerase phylogeny was not found for genes encoding virion components or for genome expression strategies. It is surmised that several types of arrangement of the "shell" genes as well as basic mechanisms of expression could have evolved independently in different evolutionary lineages. The grouping revealed by phylogenetic analysis may provide the basis for revision of virus classification, and phylogenetic taxonomy of positive-strand RNA viruses is outlined. Some of the phylogenetically derived divisions of positive-strand RNA viruses also include double-stranded RNA viruses, indicating that in certain cases the type of genome nucleic acid may not be a reliable taxonomic criterion for viruses. Hypothetical evolutionary scenarios for positive-strand RNA viruses are proposed. It is hypothesized that all positive-strand RNA viruses and some related double-stranded RNA viruses could have evolved from a common ancestor virus that contained genes for RNA-dependent RNA polymerase, a chymotrypsin-related protease that also functioned as the capsid protein, and possibly an RNA helicase.
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Affiliation(s)
- E V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894
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26
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Margis R, Pinck L. Effects of site-directed mutagenesis on the presumed catalytic triad and substrate-binding pocket of grapevine fanleaf nepovirus 24-kDa proteinase. Virology 1992; 190:884-8. [PMID: 1519363 DOI: 10.1016/0042-6822(92)90931-e] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Grapevine fanleaf nepovirus (GFLV) has a bipartite plus-sense RNA genome. Its structural and functional proteins originate from polyprotein maturation by at least one virus-encoded proteinase. Here we describe the cloning of the 24-kDa proteinase cistron located between the virus-linked protein (VPg) and the RNA-dependent RNA polymerase cistron in GFLV RNA1 (nucleotides 3966 to 4622). Proteinase expressed from this clone is able to cleave GFLV polyprotein P2 in order to produce the coat protein and a 66-kDa protein which is further processed to the 38-kDa presumed movement protein. The GFLV 24-kDa proteinase sequence contains sequence similarities with other nepovirus and comovirus proteinases, particularly at the level of the conserved domains corresponding to the hypothetical catalytic triad and to the substrate-binding pocket (amino acids 192 to 200). Site-directed mutagenesis of residues His43, Glu87, and Leu197 abolished proteinase activity. Inactivation of the enzyme is also observed if the catalytic residue Cys179 was substituted by isoleucine, but replacement by a serine at the same position produced a mutant with an activity identical to that of native proteinase. All our data show that GFLV cysteine proteinase presents structure similarities to the proteinases of cowpea mosaic virus and potyviruses but is most closely related to trypsin.
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Affiliation(s)
- R Margis
- Institut de Biologie Moléculaire des Plantes du CNRS, Université Louis Pasteur, Laboratoire de Virologie, Strasbourg, France
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27
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Dessens JT, Lomonossoff GP. Sequence upstream of the 24K protease enhances cleavage of the cowpea mosaic virus B RNA-encoded polyprotein at the junction between the 24K and 87K proteins. Virology 1992; 189:225-32. [PMID: 1604812 DOI: 10.1016/0042-6822(92)90698-o] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
To investigate cleavage at the junction between the cowpea mosaic virus (CPMV) 24K and 87K proteins, plasmids were constructed containing the sequence of bottom-component (B) RNA encoding the 110K protein plus a variable length of upstream coding sequence. Transcripts derived from these clones were translated in rabbit reticulocyte lysate and the appearance of the 87K protein was used to assess the efficiency of cleavage at the 24K-87K junction. The results show that the 110K protein, containing the contiguous sequence of the 24K and 87K proteins, is stable and that efficient cleavage at 24K-87K junction requires the presence of amino acids upstream of the 24K protease. These observations show that the 170K protein rather than the 110K protein is the precursor of the 87K protein and suggest a mechanism whereby both the B RNA-encoded 110K and 87K proteins can accumulate during infection.
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Affiliation(s)
- J T Dessens
- Department of Virus Research, John Innes Institute, Norwich, United Kingdom
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28
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Ladunga I. Phylogenetic continuum indicates "galaxies" in the protein universe: preliminary results on the natural group structures of proteins. J Mol Evol 1992; 34:358-75. [PMID: 1569589 DOI: 10.1007/bf00160244] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The markedly nonuniform, even systematic distribution of sequences in the protein "universe" has been analyzed by methods of protein taxonomy. Mapping of the natural hierarchical system of proteins has revealed some dense cores, i.e., well-defined clusterings of proteins that seem to be natural structural groupings, possibly seeds for a future protein taxonomy. The aim was not to force proteins into more or less man-made categories by discriminant analysis, but to find structurally similar groups, possibly of common evolutionary origin. Single-valued distance measures between pairs of superfamilies from the Protein Identification Resource were defined by two chi 2-like methods on tripeptide frequencies and the variable-length subsequence identity method derived from dot-matrix comparisons. Distance matrices were processed by several methods of cluster analysis to detect phylogenetic continuum between highly divergent proteins. Only well-defined clusters characterized by relatively unique structural, intracellular environmental, organismal, and functional attribute states were selected as major protein groups, including subsets of viral and Escherichia coli proteins, hormones, inhibitors, plant, ribosomal, serum and structural proteins, amino acid synthases, and clusters dominated by certain oxidoreductases and apolar and DNA-associated enzymes. The limited repertoire of functional patterns due to small genome size, the high rate of recombination, specific features of the bacterial membranes, or of the virus cycle canalize certain proteins of viruses and Gram-negative bacteria, respectively, to organismal groups.
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Affiliation(s)
- I Ladunga
- Department of Genetics, Eötvös University of Sciences, Budapest, Hungary
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29
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Beck MA, Tracy S, Coller BA, Chapman NM, Hufnagel G, Johnson JE, Lomonossoff G. Comoviruses and enteroviruses share a T cell epitope. Virology 1992; 186:238-46. [PMID: 1370127 DOI: 10.1016/0042-6822(92)90078-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
An in vitro murine T cell proliferation assay was used to determine whether an antigenic epitope(s) recognized by enterovirus-immune T cells is held in common between plant comoviruses and human enteroviruses. Splenocytes isolated from C3H/HeJ mice infected with coxsackievirus B3 (CVB3) proliferated in vitro not only against a variety of enterovirus (CVB2, CVB3, CVB6, CVA16, PV1) antigens, but against comovirus (CPMV, BPMV) antigens as well. Splenocytes from mice inoculated with bean pod mottle virus (BPMV) also proliferated in response to comoviral and enteroviral antigens in vitro. However, if the viral inocula were highly purified prior to inoculation, then the splenocyte response was generated only against the group used to inoculate, suggesting that the epitope shared between the comoviruses and the enteroviruses resided in the nonstructural region. B (nonstructural) and M (structural) genomic segments of CPMV were translated in rabbit reticulocyte lysates and used as in vitro antigens. Splenocytes from mice inoculated with live CVB3 proliferated in response to the B-RNA-encoded but not the M-RNA-encoded polypeptides, confirming the nonstructural coding region location of the common epitope. Comparison of predicted amino acid sequences in the nonstructural coding regions of the comoviruses and picornaviruses suggested a potentially immunogenic linear epitope in protein 2C. The consensus peptide LEEKGI was synthezized and shown to be immunogenic for both BPMV- and CVB3-immune splenocytes.
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Affiliation(s)
- M A Beck
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha 68198
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30
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David C, Gargouri-Bouzid R, Haenni AL. RNA replication of plant viruses containing an RNA genome. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1992; 42:157-227. [PMID: 1574587 DOI: 10.1016/s0079-6603(08)60576-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- C David
- Institut Jacques Monod, Paris, France
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31
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Affiliation(s)
- P Palukaitis
- Department of Plant Pathology, Cornell University, Ithaca, New York 14853
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32
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Levis C, Tronchet M, Meyer M, Albouy J, Astier-Manifacier S. Effects of antisense oligodeoxynucleotide hybridization on in vitro translation of potato virus Y RNA. Virus Genes 1992; 6:33-46. [PMID: 1549909 DOI: 10.1007/bf01703755] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Potato virus Y (PVY), a potyvirus, has an RNA genome containing 9704 nucleotides of which 185 belong to the 5' nontranslated region (NTR). Contrary to most eukaryotic mRNAs that have a cap structure, the potyvirus RNA has a genome-linked protein (VPg). In order to understand the mechanisms of PVY RNA translation initiation, hybrid-arrest translation was used to localize sequences involved in binding of proteins and/or ribosomes. The 5' NTR was fused to the beta-glucuronidase (GUS) reporter gene. Six antisense oligodeoxynucleotides were used for hybridization, and the efficiency of the in vitro translation of the hybridized mRNA was modified to different levels depending upon the position of the oligodeoxynucleotide used. The highest inhibition was obtained with an oligodeoxynucleotide hybridized to the 5' end. In addition, translation of GUS mRNA containing the PVY 5' NTR was greatly enhanced when this mRNA was capped. These results differ from those obtained with the tobacco etch virus (TEV) and three picornaviruses, but are similar to those obtained with capped mRNA.
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Affiliation(s)
- C Levis
- Station de Phytopathologie, Institut National de la Recherche Agronomique, Versailles, France
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33
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Abstract
The explosive pace of sequencing of RNA viruses is leading to rapid advances in our understanding of the evolution of these viruses and of the ways in which their genomes are organized and expressed. New insights are coming not only from genomic nucleotide sequence comparisons, but also from direct sequencing of transcribed mRNAs and of RNAs that serve as intermediates in replication.
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Key Words
- bsmv, barley stripe mosaic virus
- l, large
- ldr, leader rna
- m, medium
- ndv, newcastle disease virus
- ntr, non-translated region
- orf, open reading frame
- piv, parainfluenza virus
- s, small
- ssrna, single-strand rna
- sv5, simian virus 5
- tmv, tobacco mosaic virus
- vc rna, virus complementary rna
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Affiliation(s)
- E G Strauss
- Division of Biology, California Institute of Technology, Pasadena 91125
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34
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Abstract
This review summarizes some of the results obtained from the crystal structure determination of viruses. The structural similarities of viral coat proteins is discussed, as well as some structural results related to the regulation of viral disassembly.
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Affiliation(s)
- L Liljas
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907
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35
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Dessens JT, Lomonossoff GP. Mutational analysis of the putative catalytic triad of the cowpea mosaic virus 24K protease. Virology 1991; 184:738-46. [PMID: 1887592 DOI: 10.1016/0042-6822(91)90444-g] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
To investigate the mechanism of action of the cowpea mosaic virus (CPMV) 24K protease, a full-length cDNA clone of bottom component (B) RNA has been constructed from which RNA can be transcribed in vitro using T7 RNA polymerase. Translation of the resulting RNA in rabbit reticulocyte lysate leads to the synthesis of a 200 kDa product (the 200K protein) which cleaves itself in a manner identical to that of the product translated from B RNA isolated from virions. Site-directed mutagenesis of the full-length clone was used to examine the effects of altering individual amino acids in the 24K protease on its activity. The results obtained are consistent with the prediction that the 24K protease is structurally similar to the trypsin-like family of serine proteases and suggest that His40, Glu76, and Cys166 comprise the active site. Substitution of Cys166 by a serine residue results in an enzyme with reduced catalytic activity.
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Affiliation(s)
- J T Dessens
- Department of Virus Research, John Innes Institute, Norwich, United Kingdom
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36
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Jackson RJ. The ATP requirement for initiation of eukaryotic translation varies according to the mRNA species. EUROPEAN JOURNAL OF BIOCHEMISTRY 1991; 200:285-94. [PMID: 1889398 DOI: 10.1111/j.1432-1033.1991.tb16184.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The requirement for ATP for initiation of eukaryotic mRNA translation was tested using gel-filtered rabbit reticulocyte lysates incubated with labelled Met-tRNAfMet and exogenous RNA templates, and assaying the formation of labelled 80S initiation complexes in the presence of GTP, or labelled 40S initiation complexes in the presence of a non-hydrolysable analogue of GTP. Initiation complex formation on globin mRNA, or on capped viral RNAs such as papaya mosaic virus RNA and tobacco mosaic virus RNA, was strongly stimulated by ATP. In contrast, initiation complex formation on (uncapped) encephalomyocarditis virus RNA was uninfluenced by the presence or absence of ATP, which may be correlated with the recent evidence for scanning-independent internal initiation on this viral RNA. In addition, initiation complex formation on uncapped cowpea mosaic virus RNA and on poly(A,U,G) was only slightly stimulated by ATP, much less than in the case of the capped RNAs. These results suggest that most of the ATP hydrolysed during translation initiation is consumed in cap-dependent processes, probably in unwinding the mRNA, and relatively little in the actual migration or scanning of 40S subunits along the mRNA.
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Affiliation(s)
- R J Jackson
- Department of Biochemistry, University of Cambridge, England
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37
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Lomonossoff GP, Johnson JE. The synthesis and structure of comovirus capsids. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 1991; 55:107-37. [PMID: 1871315 DOI: 10.1016/0079-6107(91)90003-b] [Citation(s) in RCA: 118] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- G P Lomonossoff
- Department of Virus Research, John Innes Institute, John Innes Centre for Plant Science Research, Norwich, U.K
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38
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Abstract
Picornaviruses are small naked icosahedral viruses with a single-stranded RNA genome of positive polarity. According to current taxonomy, the family includes four genera: Enterouirus (polioviruses, coxsackieviruses, echoviruses, and other enteroviruses), Rhinovirus, Curdiouirus [encephalomyocarditis virus (EMCV), mengovirus, Theiler's murine encephalomyelitis virus (TMEV)], and Aphthouirus [foot-and-mouth disease viruses (FMDV)]. There are also some, as yet, unclassified picornaviruses [e.g., hepatitis A virus (HAW] that should certainly be assessed as a separate genus. Studies on the molecular biology of picornaviruses might be divided into two periods: those before and after the first sequencing of the poliovirus genome. The 5'-untranslated region (5-UTR) of the viral genome was one of the unexpected problems. This segment proved to be immensely long: about 750 nucleotides or ∼10% of the genome length. There were also other unusual features (e.g., multiple AUG triplets preceding the single open reading frame (ORF) that encodes the viral polyprotein). This chapter shows that the picornaviral 5-UTRs are not only involved in such essential events as the synthesis of viral proteins and RNAs that could be expected to some extent, although some of the underlying mechanisms appeared to be quite a surprise, but also may determine diverse biological phenotypes from the plaque size or thermosensitivity of reproduction to attenuation of neurovirulence. Furthermore, a close inspection of the 5-UTR structure unravels certain hidden facets of the evolution of the picornaviral genome. Finally, the conclusions drawn from the experiments with the picornaviral5-UTRs provide important clues for understanding the functional capabilities of the eukaryotic ribosomes.
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Affiliation(s)
- V I Agol
- Institute of Poliomyelitis and Viral Encephalitides, U.S.S.R. Academy of Medical Sciences, Moscow
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39
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Site-directed mutagenesis suggests close functional relationship between a human rhinovirus 3C cysteine protease and cellular trypsin-like serine proteases. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)39096-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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40
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Candresse T, Morch MD, Dunez J. Multiple alignment and hierarchical clustering of conserved amino acid sequences in the replication-associated proteins of plant RNA viruses. RESEARCH IN VIROLOGY 1990; 141:315-29. [PMID: 2392616 DOI: 10.1016/0923-2516(90)90003-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We have used multiple alignment computer programs to align and hierarchically cluster the conserved amino acid "signature" sequences found in the replication-associated proteins of all plant RNA viruses sequenced so far. These regions, called "polymerase", "nucleotide-binding" and "N-terminal" are well conserved even between viruses which are only distantly related, and are thus very well suited for this type of analysis. Our results show that the clusterings obtained using these very short amino acid sequences are very robust to computing parameters and are surprisingly well matched with the taxonomic grouping of RNA plant viruses. The possibility of using this system as a new taxonomic criterion is discussed.
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Affiliation(s)
- T Candresse
- Station de Pathologie Végétale, Centre de Recherches de Bordeaux, INRA, Villenave d'Ornon Cedex, France
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41
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Abstract
A revertant was isolated from a temperature-sensitive poliovirus 2C mutant, 2C-31, which is defective in viral RNA synthesis. This revertant, called 2C-31R1, grew well at 39 degrees C and was not defective in RNA synthesis. However, in contrast to its parental mutant, 2C-31R1 was cold sensitive and could hardly grow at all at 32 degrees C. Analysis of a single-cycle growth revealed that 2C-31R1 was defective in virion uncoating at 32 degrees C, and a substantial amount (more than 30%) of input viruses could be recovered as infectious particles from an infected cell lysate up to 6 h postinfection. The uncoating defect and the inability to grow at cold temperatures could be overcome by a brief incubation at the permissive temperature (39 degrees C) before the infection was continued at 32 degrees C. cDNA cloning and mix-and-match recombination experiments indicated that the defect in uncoating was the result of two secondary point mutations, seven nucleotides apart, in the 2C-coding sequence downstream of the inserted linker which is the original mutation in the parental 2C-31 genome. Another revertant, 2C-31R3, isolated from the same 2C-31 stock, was not defective in uncoating and appeared to be a secondary revertant that contained an intragenic suppressor for the uncoating defect. The uncoating defect of 2C-31R1 could be complemented by type 2 poliovirus. These results suggested that protein 2C, in addition to its role in viral RNA synthesis, has a function in determining virion structure.
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Affiliation(s)
- J P Li
- Whitehead Institute for Biomedical Research, Nine Cambridge Center, Massachusetts 02142
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42
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Lawson MA, Semler BL. Picornavirus Protein Processing—Enzymes, Substrates, and Genetic Regulation. Curr Top Microbiol Immunol 1990. [DOI: 10.1007/978-3-642-75602-3_3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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43
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Poch O, Sauvaget I, Delarue M, Tordo N. Identification of four conserved motifs among the RNA-dependent polymerase encoding elements. EMBO J 1989; 8:3867-74. [PMID: 2555175 PMCID: PMC402075 DOI: 10.1002/j.1460-2075.1989.tb08565.x] [Citation(s) in RCA: 776] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Four consensus sequences are conserved with the same linear arrangement in RNA-dependent DNA polymerases encoded by retroid elements and in RNA-dependent RNA polymerases encoded by plus-, minus- and double-strand RNA viruses. One of these motifs corresponds to the YGDD span previously described by Kamer and Argos (1984). These consensus sequences altogether lead to 4 strictly and 18 conservatively maintained amino acids embedded in a large domain of 120 to 210 amino acids. As judged from secondary structure predictions, each of the 4 motifs, which may cooperate to form a well-ordered domain, places one invariant amino acid in or proximal to turn structures that may be crucial for their correct positioning in a catalytic process. We suggest that this domain may constitute a prerequisite 'polymerase module' implicated in template seating and polymerase activity. At the evolutionary level, the sequence similarities, gap distribution and distances between each motif strongly suggest that the ancestral polymerase module was encoded by an individual genetic element which was most closely related to the plus-strand RNA viruses and the non-viral retroposons. This polymerase module gene may have subsequently propagated in the viral kingdom by distinct gene set recombination events leading to the wide viral variety observed today.
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Affiliation(s)
- O Poch
- Institut de Biologie Moléculaire et Cellulaire du CNRS, Strabourg, France
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44
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Keese P, Mackenzie A, Gibbs A. Nucleotide sequence of the genome of an Australian isolate of turnip yellow mosaic tymovirus. Virology 1989; 172:536-46. [PMID: 2800335 DOI: 10.1016/0042-6822(89)90196-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The nucleotide sequence of the Club Lake isolate of turnip yellow mosaic virus (TYMV-CL) genomic RNA has been determined. The genome is 6319 nucleotide residues in length and has three major open reading frames (ORFs), two of which overlap. The smallest ORF is proximal to the 3' terminus and encodes the virion protein gene, which has 98% sequence similarity with the virion protein gene reported for the type strain of TYMV. The largest ORF is from nucleotide residues 96 to 5630, and encodes a protein some parts of which show sequence similarities to the possible RNA replicases and nucleotide binding proteins of other viruses. The third ORF is from nucleotide residues 89 to 1975 and overlaps the 5' end of the largest ORF in a manner similar to that found in several animal viral genomes. The function of the protein encoded by this ORF is unknown. The genomes of tymoviruses have, characteristically, an unusually large cytosine content and small guanosine content. This compositional bias is mirrored in the codon and dinucleotide frequencies of the TYMV-CL genome, but is only partially reflected in the amino acid sequences encoded by the genome.
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Affiliation(s)
- P Keese
- Research School of Biological Sciences, Australian National University, Canberra
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45
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Chen ZG, Stauffacher C, Li Y, Schmidt T, Bomu W, Kamer G, Shanks M, Lomonossoff G, Johnson JE. Protein-RNA interactions in an icosahedral virus at 3.0 A resolution. Science 1989; 245:154-9. [PMID: 2749253 DOI: 10.1126/science.2749253] [Citation(s) in RCA: 177] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Nearly 20 percent of the packaged RNA in bean-pod mottle virus (BPMV) binds to the capsid interior in a symmetric fashion and is clearly visible in the electron density map. The RNA displaying icosahedral symmetry is single-stranded with well-defined polarity and stereochemical properties. Interactions with protein are dominated by nonbonding forces with few specific contacts. The tertiary and quaternary structures of the BPMV capsid proteins are similar to those observed in animal picornaviruses, supporting the close relation between plant comoviruses and animal picornaviruses established by previous biological studies.
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Affiliation(s)
- Z G Chen
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907
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46
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Morozov SYu, Dolja VV, Atabekov JG. Probable reassortment of genomic elements among elongated RNA-containing plant viruses. J Mol Evol 1989; 29:52-62. [PMID: 2504930 PMCID: PMC7087513 DOI: 10.1007/bf02106181] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/1988] [Revised: 10/26/1988] [Indexed: 01/01/2023]
Abstract
The relationships of genome organization among elongated (rod-shaped and filamentous) plant viruses have been analyzed. Sequences in coding and noncoding regions of barley stripe mosaic virus (BSMV) RNAs 1, 2, and 3 were compared with those of the monopartite RNA genomes of potato virus X (PVX), white clover mosaic virus (WClMV), and tobacco mosaic virus, the bipartite genome of tobacco rattle virus (TRV), the quadripartite genome of beet necrotic yellow vein virus (BNYVV), and icosahedral tricornaviruses. These plant viruses belong to a supergroup having 5'-capped genomic RNAs. The results suggest that the genomic elements in each BSMV RNA are phylogenetically related to those of different plant RNA viruses. RNA 1 resembles the corresponding RNA 1 of tricornaviruses. The putative proteins encoded in BSMV RNA 2 are related to the products of BNYVV RNA 2, PVX RNA, and WClMV RNA. Amino acid sequence comparisons suggest that BSMV RNA 3 resembles TRV RNA 1. Also, it can be proposed that in the case of monopartite genomes, as a rule, every gene or block of genes retains phylogenetic relationships that are independent of adjacent genomic elements of the same RNA. Such differential evolution of individual elements of one and the same viral genome implies a prominent role for gene reassortment in the formation of viral genetic systems.
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Affiliation(s)
- Morozov SYu
- Department of Virology, Moscow State University, USSR
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47
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Richards OC, Eggen R, Goldbach R, van Kammen A. High-level synthesis of cowpea mosaic virus RNA polymerase and protease in Escherichia coli. Gene X 1989; 78:135-46. [PMID: 2548928 DOI: 10.1016/0378-1119(89)90321-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
An expression system for the production of polymerase proteins of cowpea mosaic virus (CPMV) in Escherichia coli cells is described. High-level synthesis of proteins containing protease and polymerase moieties (110-kDa protein) and polymerase alone (87-kDa protein) were obtained from cells containing different plasmid constructions. Precursor and processed forms of CPMV proteins were detected by immunoblotting with antisera directed against 170-kDa precursor polyprotein and 24-kDa viral protease. Crude lysates and supernatant fractions of the lysates from E. coli cells harboring the various plasmid constructions were analysed for poly(A)-oligo(U) polymerase activity and found to be negative for CPMV activity under conditions where similar expression systems for the production of poliovirus RNA polymerase activity were positive. Thus, conditions for CPMV RNA replication may indeed be different from those for poliovirus even though the genomic organization of these viruses is similar.
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Affiliation(s)
- O C Richards
- Department of Molecular Biology, Agricultural University, Wageningen, The Netherlands
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48
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Gorbalenya AE, Blinov VM, Donchenko AP, Koonin EV. An NTP-binding motif is the most conserved sequence in a highly diverged monophyletic group of proteins involved in positive strand RNA viral replication. J Mol Evol 1989; 28:256-68. [PMID: 2522556 PMCID: PMC7087505 DOI: 10.1007/bf02102483] [Citation(s) in RCA: 150] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/1988] [Revised: 04/10/1988] [Indexed: 01/01/2023]
Abstract
NTP-motif, a consensus sequence previously shown to be characteristic of numerous NTP-utilizing enzymes, was identified in nonstructural proteins of several groups of positive-strand RNA viruses. These groups include picorna-, alpha-, and coronaviruses infecting animals and como-, poty-, tobamo-, tricorna-, hordei-, and furoviruses of plants, totalling 21 viruses. It has been demonstrated that the viral NTP-motif-containing proteins constitute three distinct families, the sequences within each family being similar to each other at a statistically highly significant level. A lower, but still valid similarity has also been revealed between the families. An overall alignment has been generated, which includes several highly conserved sequence stretches. The two most prominent of the latter contain the socalled "A" and "B" sites of the NTP-motif, with four of the five invariant amino acid residues observed within these sequences. These observations, taken together with the results of comparative analysis of the positions occupied by respective proteins (domains) in viral multidomain proteins, suggest that all the NTP-motif-containing proteins of positive-strand RNA viruses are homologous, constituting a highly diverged monophyletic group. In this group the "A" and "B" sites of the NTP-motif are the most conserved sequences and, by inference, should play the principal role in the functioning of the proteins. A hypothesis is proposed that all these proteins possess NTP-binding capacity and possibly NTPase activity, performing some NTP-dependent function in viral RNA replication. The importance of phylogenetic analysis for the assessment of the significance of the occurrence of the NTP-motif (and of sequence motifs of this sort in general) in proteins is emphasized.
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Affiliation(s)
- A E Gorbalenya
- Institute of Poliomyelitis, USSR Academy of Medical Sciences, Moscow Region
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49
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Villaverde A, Martínez-Salas E, Domingo E. 3D gene of foot-and-mouth disease virus. Conservation by convergence of average sequences. J Mol Biol 1988; 204:771-6. [PMID: 3225850 DOI: 10.1016/0022-2836(88)90367-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The nucleotide sequence of the 3D (polymerase) gene of eight epidemiologically related isolates of foot-and-mouth disease virus of serotype C1 is reported. The genetic heterogeneity of 3D RNA is compared with that of the VP1-coding RNA of the same viruses. Regression lines of substitutions per nucleotide that distinguish any pair of viruses as a function of the time interval between the corresponding isolations show: (1) the slope (substitutions/nucleotide per month) is 2.1 times larger for the VP1 RNA than for the 3D RNA region; (2) the intercept with the ordinate (substitutions/nucleotide) for VP1 RNA is indistinguishable from that for 3D RNA. Thus, the average heterogeneity of the VP1-coding region is very similar to that of the 3D-coding region only among co-circulating viruses. Nine mutations and points of heterogeneity occurred within nucleotide residues 883 to 1026, which encode an amino acid segment, extremely conserved among many different RNA viruses. The results suggest that, rather than due to inherently lower mutability, the conservation of 3D genes is caused by a limitation in the fixation of substitutions in viable genomes.
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Affiliation(s)
- A Villaverde
- Centro de Biología Molecular (CSIC-UAM), Universidad Autónoma de Madrid, Spain
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50
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Sacher R, French R, Ahlquist P. Hybrid brome mosaic virus RNAs express and are packaged in tobacco mosaic virus coat protein in vivo. Virology 1988; 167:15-24. [PMID: 2847411 DOI: 10.1016/0042-6822(88)90049-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Brome mosaic virus (BMV) is an icosahedral virus with a tripartite RNA genome which infects monocotyledonous plants, while the cowpea or legume strain of tobacco mosaic virus (CcTMV) is a rod-shaped virus with a single component RNA genome which infects dicotyledonous plants. To examine the potential for exchanging entire genes between RNA viruses, biologically active cDNA clones were used to replace the natural coat gene of BMV RNA3 with the coat gene and encapsidation origin of CcTMV. In protoplasts coinoculated with BMV RNAs 1 and 2, the resulting hybrid RNA3 was replicated by BMV trans-acting factors but was packaged in TMV coat protein to give rod-shaped particles rather than the usual BMV icosahedra. When the CcTMV encapsidation origin was suitably inserted in derivatives of BMV RNAs 1 and 2, these RNAs were also packaged in a ribonuclease-resistant form in protoplasts coinoculated with the hybrid RNA3 expressing TMV rather than BMV coat protein. Thus, despite the markedly divergent nature of BMV and TMV, replicating hybrids bearing characters derived from both parent viruses were produced. Such hybrid viruses could be of considerable value for studying specific steps in infection and for assigning functions to particular virus genes.
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Affiliation(s)
- R Sacher
- Institute for Molecular Virology, University of Wisconsin, Madison 53706
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