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Wulan WN, Heydet D, Walker EJ, Gahan ME, Ghildyal R. Nucleocytoplasmic transport of nucleocapsid proteins of enveloped RNA viruses. Front Microbiol 2015; 6:553. [PMID: 26082769 PMCID: PMC4451415 DOI: 10.3389/fmicb.2015.00553] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 05/19/2015] [Indexed: 12/25/2022] Open
Abstract
Most viruses with non-segmented single stranded RNA genomes complete their life cycle in the cytoplasm of infected cells. However, despite undergoing replication in the cytoplasm, the structural proteins of some of these RNA viruses localize to the nucleus at specific times in the virus life cycle, primarily early in infection. Limited evidence suggests that this enhances successful viral replication by interfering with or inhibiting the host antiviral response. Nucleocapsid proteins of RNA viruses have a well-established, essential cytoplasmic role in virus replication and assembly. Intriguingly, nucleocapsid proteins of some RNA viruses also localize to the nucleus/nucleolus of infected cells. Their nuclear function is less well understood although significant advances have been made in recent years. This review will focus on the nucleocapsid protein of cytoplasmic enveloped RNA viruses, including their localization to the nucleus/nucleolus and function therein. A greater understanding of the nuclear localization of nucleocapsid proteins has the potential to enhance therapeutic strategies as it can be a target for the development of live-attenuated vaccines or antiviral drugs.
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Affiliation(s)
- Wahyu N Wulan
- Centre for Research in Therapeutic Solutions, University of Canberra, Bruce, ACT Australia ; Faculty of Education, Science, Technology and Mathematics, University of Canberra, Bruce, ACT Australia
| | - Deborah Heydet
- Centre for Research in Therapeutic Solutions, University of Canberra, Bruce, ACT Australia
| | - Erin J Walker
- Centre for Research in Therapeutic Solutions, University of Canberra, Bruce, ACT Australia
| | - Michelle E Gahan
- Faculty of Education, Science, Technology and Mathematics, University of Canberra, Bruce, ACT Australia
| | - Reena Ghildyal
- Centre for Research in Therapeutic Solutions, University of Canberra, Bruce, ACT Australia ; Faculty of Education, Science, Technology and Mathematics, University of Canberra, Bruce, ACT Australia
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Application of minigenome technology in virology research of the Paramyxoviridae family. JOURNAL OF MICROBIOLOGY, IMMUNOLOGY, AND INFECTION = WEI MIAN YU GAN RAN ZA ZHI 2014; 48:123-9. [PMID: 24767419 DOI: 10.1016/j.jmii.2014.02.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 01/12/2014] [Accepted: 02/19/2014] [Indexed: 11/23/2022]
Abstract
Minigenomes (MGs) are complementary DNAs of the synthetic analogs of genomic RNA. MGs are widely used to study the life cycle of the Paramyxoviridae family of viruses. MG-based studies have provided valuable insights into the mechanisms of viral replication and transcription in this family, including the roles of viral proteins, the location and boundaries of the cis-acting elements, the functional domains of trans-acting proteins, techniques for the measurement of neutralizing antibody, virus-host interactions, and the structure and function of viral RNA. This article provides a brief overview of the principle and application of MG technology in studies involving members of the Paramyxoviridae family. The advantages, potential limitations, and future scope of MG technology are also discussed.
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Characterization of a viral phosphoprotein binding site on the surface of the respiratory syncytial nucleoprotein. J Virol 2012; 86:8375-87. [PMID: 22623798 DOI: 10.1128/jvi.00058-12] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The human respiratory syncytial virus (HRSV) genome is composed of a negative-sense single-stranded RNA that is tightly associated with the nucleoprotein (N). This ribonucleoprotein (RNP) complex is the template for replication and transcription by the viral RNA-dependent RNA polymerase. RNP recognition by the viral polymerase involves a specific interaction between the C-terminal domain of the phosphoprotein (P) (P(CTD)) and N. However, the P binding region on N remains to be identified. In this study, glutathione S-transferase (GST) pulldown assays were used to identify the N-terminal core domain of HRSV N (N(NTD)) as a P binding domain. A biochemical characterization of the P(CTD) and molecular modeling of the N(NTD) allowed us to define four potential candidate pockets on N (pocket I [PI] to PIV) as hydrophobic sites surrounded by positively charged regions, which could constitute sites complementary to the P(CTD) interaction domain. The role of selected amino acids in the recognition of the N-RNA complex by P was first screened for by site-directed mutagenesis using a polymerase activity assay, based on an HRSV minigenome containing a luciferase reporter gene. When changed to Ala, most of the residues of PI were found to be critical for viral RNA synthesis, with the R132A mutant having the strongest effect. These mutations also reduced or abolished in vitro and in vivo P-N interactions, as determined by GST pulldown and immunoprecipitation experiments. The pocket formed by these residues is critical for P binding to the N-RNA complex, is specific for pneumovirus N proteins, and is clearly distinct from the P binding sites identified so far for other nonsegmented negative-strand viruses.
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Tedcastle AB, Fenwick F, Ingram RE, King BJ, Robinson MJ, Toms GL. The characterization of monoclonal antibodies to human metapneumovirus and the detection of multiple forms of the virus nucleoprotein and phosphoprotein. J Med Virol 2012; 84:1061-70. [DOI: 10.1002/jmv.23298] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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5
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Mutations in the fusion protein cleavage site of avian paramyxovirus serotype 2 increase cleavability and syncytium formation but do not increase viral virulence in chickens. J Virol 2011; 85:5394-405. [PMID: 21450835 DOI: 10.1128/jvi.02696-10] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Avian paramyxovirus serotype 2 (APMV-2) is one of the nine serotypes of APMV, which infect a wide variety of avian species around the world. In this study, we constructed a reverse genetics system for recovery of infectious recombinant APMV-2 strain Yucaipa (APMV-2/Yuc) from cloned cDNA. The rescued recombinant virus (rAPMV-2) resembled the biological virus in growth properties in vitro and in pathogenicity in vivo. The reverse genetics system was used to analyze the role of the cleavage site of the fusion (F) protein in viral replication and pathogenesis. The cleavage site of APMV-2/Yuc (KPASR↓F) contains only a single basic residue (position -1) that matches the preferred furin cleavage site [RX(K/R)R↓]. (Underlining indicates the basic amino acids at the F protein cleavage site, and the arrow indicates the site of cleavage.) Contrary to what would be expected for this cleavage sequence, APMV-2 does not require, and is not augmented by, exogenous protease supplementation for growth in cell culture. However, it does not form syncytia, and the virus is avirulent in chickens. A total of 12 APMV-2 mutants with F protein cleavage site sequences derived from APMV serotypes 1 to 9 were generated. These sites contain from 1 to 5 basic residues. Whereas a number of these cleavage sites are associated with protease dependence and lack of syncytium formation in their respective native viruses, when transferred into the APMV-2 backbone, all of them conferred protease independence, syncytium formation, and increased replication in cell culture. Examination of selected mutants during a pulse-chase experiment demonstrated an increase in F protein cleavage compared to that for wild-type APMV-2. Despite the gains in cleavability, replication, and syncytium formation, analysis of viral pathogenicity in 9-day-old embryonated chicken eggs, 1-day-old chicks, and 2-week-old chickens showed that the F protein cleavage site mutants did not exhibit increased pathogenicity and remained avirulent. These results imply that structural features in addition to the cleavage site play a major role in the cleavability of the F protein and the activity of the cleaved protein. Furthermore, cleavage of the F protein is not a determinant of APMV-2 pathogenicity in chickens.
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El Omari K, Scott K, Dhaliwal B, Ren J, Abrescia NGA, Budworth J, Lockyer M, Powell KL, Hawkins AR, Stammers DK. Crystallization and preliminary X-ray analysis of the human respiratory syncytial virus nucleocapsid protein. Acta Crystallogr Sect F Struct Biol Cryst Commun 2008; 64:1019-23. [PMID: 18997331 PMCID: PMC2581706 DOI: 10.1107/s1744309108031059] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2008] [Accepted: 09/25/2008] [Indexed: 11/10/2022]
Abstract
Human respiratory syncytial virus (HRSV) has a nonsegmented negative-stranded RNA genome which is encapsidated by the HRSV nucleocapsid protein (HRSVN) that is essential for viral replication. HRSV is a common cause of respiratory infection in infants, yet no effective antiviral drugs to combat it are available. Recent data from an experimental anti-HRSV compound, RSV-604, indicate that HRSVN could be the target site for drug action. Here, the expression, purification and preliminary data collection of decameric HRSVN as well as monomeric N-terminally truncated HRSVN mutants are reported. Two different crystal forms of full-length selenomethionine-labelled HRSVN were obtained that diffracted to 3.6 and approximately 5 A resolution and belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 133.6, b = 149.9, c = 255.1 A, and space group P2(1), with unit-cell parameters a = 175.1, b = 162.6, c = 242.8 A, beta = 90.1 degrees , respectively. For unlabelled HRSVN, only crystals belonging to space group P2(1) were obtained that diffracted to 3.6 A. A self-rotation function using data from the orthorhombic crystal form confirmed the presence of tenfold noncrystallographic symmetry, which is in agreement with a reported electron-microscopic reconstruction of HRSVN. Monomeric HRSVN generated by N-terminal truncation was designed to assist in structure determination by reducing the size of the asymmetric unit. Whilst such HRSVN mutants were monomeric in solution and crystallized in a different space group, the size of the asymmetric unit was not reduced.
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Affiliation(s)
- K. El Omari
- Division of Structural Biology, The Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, England
| | - K. Scott
- Division of Structural Biology, The Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, England
| | - B. Dhaliwal
- Division of Structural Biology, The Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, England
| | - J. Ren
- Division of Structural Biology, The Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, England
| | - N. G. A. Abrescia
- Division of Structural Biology, The Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, England
| | - J. Budworth
- Arrow Therapeutics Ltd, Britannia House, Trinity Street, Borough, London SE1 1DB, England
| | - M. Lockyer
- Arrow Therapeutics Ltd, Britannia House, Trinity Street, Borough, London SE1 1DB, England
| | - K. L. Powell
- Arrow Therapeutics Ltd, Britannia House, Trinity Street, Borough, London SE1 1DB, England
| | - A. R. Hawkins
- Institute of Cell and Molecular Biosciences, Catherine Cookson Building, Medical School, Framlington Place, Newcastle University, Newcastle-upon-Tyne NE2 4HH, England
| | - D. K. Stammers
- Division of Structural Biology, The Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, England
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Asenjo A, Mendieta J, Gómez-Puertas P, Villanueva N. Residues in human respiratory syncytial virus P protein that are essential for its activity on RNA viral synthesis. Virus Res 2008; 132:160-73. [PMID: 18179840 DOI: 10.1016/j.virusres.2007.11.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 11/22/2007] [Accepted: 11/22/2007] [Indexed: 11/19/2022]
Abstract
Human respiratory syncytial virus (HRSV) P protein, 241 amino acid long, is a structural homotetrameric phosphoprotein. Viral transcription and replication processes are dependent on functional P protein interactions inside viral ribonucleoprotein complexes (RNPs). Binding capacity to RNPs proteins and transcription and replication complementation analyses, using inactive P protein variants, have identified residues essential for functional interactions with itself, L, N and M2-1 proteins. P protein may establish some of these interactions as monomer, but efficient viral transcription and replication requires P protein oligomerization through the central region of the molecule. A structurally stable three-dimensional model has been generated in silico for this region (residues 98-158). Our analysis has indicated that P protein residues L135, D139, E140 and L142 are involved in homotetramerization. Additionally, the residues D136, S156, T160 and E179 appear to be essential for P protein activity on viral RNA synthesis and very high turnover phosphorylation at S143, T160 and T210 could regulate it. Thus, compounds targeted to those of these residues, located in the modeled three-dimensional structure, could have specific anti-HRSV effect.
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Affiliation(s)
- Ana Asenjo
- Instituto de Salud Carlos III, Ctra. Majadahonda, Madrid 28220, Spain
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Maclellan K, Loney C, Yeo RP, Bhella D. The 24-angstrom structure of respiratory syncytial virus nucleocapsid protein-RNA decameric rings. J Virol 2007; 81:9519-24. [PMID: 17567697 PMCID: PMC1951410 DOI: 10.1128/jvi.00526-07] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Respiratory syncytial virus (RSV), a nonsegmented, negative-sense RNA-containing virus, is a common cause of lower respiratory tract disease. Expression of RSV nucleocapsid protein (N) in insect cells using the baculovirus expression system leads to the formation of N-RNA complexes that are morphologically indistinguishable from viral nucleocapsids. When imaged in an electron microscope, three distinct types of structures were observed: tightly wound short-pitch helices, highly extended helices, and rings. Negative stain images of N-RNA rings were used to calculate a three-dimensional reconstruction at 24 A resolution, revealing features similar to those observed in nucleocapsids from other viruses of the order Mononegavirales. The reconstructed N-RNA rings comprise 10 N monomers and have an external radius of 83 A and an internal radius of 40 A. Comparison of this structure with crystallographic data from rabies virus and vesicular stomatitis virus N-RNA rings reveals striking morphological similarities.
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Affiliation(s)
- Kirsty Maclellan
- Medical Research Council Virology Unit, Institute of Virology, Church Street, Glasgow G11 5JR, United Kingdom
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Cowton VM, McGivern DR, Fearns R. Unravelling the complexities of respiratory syncytial virus RNA synthesis. J Gen Virol 2006; 87:1805-1821. [PMID: 16760383 DOI: 10.1099/vir.0.81786-0] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Human respiratory syncytial virus (RSV) is the leading cause of paediatric respiratory disease and is the focus of antiviral- and vaccine-development programmes. These goals have been aided by an understanding of the virus genome architecture and the mechanisms by which it is expressed and replicated. RSV is a member of the order Mononegavirales and, as such, has a genome consisting of a single strand of negative-sense RNA. At first glance, transcription and genome replication appear straightforward, requiring self-contained promoter regions at the 3' ends of the genome and antigenome RNAs, short cis-acting elements flanking each of the genes and one polymerase. However, from these minimal elements, the virus is able to generate an array of capped, methylated and polyadenylated mRNAs and encapsidated antigenome and genome RNAs, all in the appropriate ratios to facilitate virus replication. The apparent simplicity of genome expression and replication is a consequence of considerable complexity in the polymerase structure and its cognate cis-acting sequences; here, our understanding of mechanisms by which the RSV polymerase proteins interact with signals in the RNA template to produce different RNA products is reviewed.
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MESH Headings
- Base Sequence
- DNA-Directed RNA Polymerases/metabolism
- Genome, Viral
- Humans
- Models, Biological
- Molecular Sequence Data
- Mononegavirales/genetics
- Mononegavirales/physiology
- Nucleocapsid/biosynthesis
- Nucleocapsid/genetics
- RNA, Antisense/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Viral/biosynthesis
- RNA, Viral/genetics
- Respiratory Syncytial Virus, Human/genetics
- Respiratory Syncytial Virus, Human/pathogenicity
- Respiratory Syncytial Virus, Human/physiology
- Transcription, Genetic
- Viral Proteins/metabolism
- Virus Replication
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Affiliation(s)
- Vanessa M Cowton
- Division of Pathology and Neuroscience, University of Dundee Medical School, Dundee DD1 9SY, UK
| | - David R McGivern
- Division of Pathology and Neuroscience, University of Dundee Medical School, Dundee DD1 9SY, UK
| | - Rachel Fearns
- Division of Pathology and Neuroscience, University of Dundee Medical School, Dundee DD1 9SY, UK
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Brown G, Rixon HWM, Steel J, McDonald TP, Pitt AR, Graham S, Sugrue RJ. Evidence for an association between heat shock protein 70 and the respiratory syncytial virus polymerase complex within lipid-raft membranes during virus infection. Virology 2005; 338:69-80. [PMID: 15936795 DOI: 10.1016/j.virol.2005.05.004] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2005] [Revised: 03/15/2005] [Accepted: 05/03/2005] [Indexed: 11/24/2022]
Abstract
In this report, the interaction between respiratory syncytial virus (RSV) and heat shock protein 70 (HSP70) was examined. Although no significant increase in total HSP70 protein levels was observed during virus infection, analysis of the HSP70 content in lipid-raft membranes from mock- and virus-infected cells revealed an increase in the levels of raft-associated HSP70 during virus infection. Fluorescence microscopy demonstrated that this transport of HSP70 into lipid-raft membranes correlated with the appearance of HSP70 within virus-induced inclusion bodies. Furthermore, co-localisation of HSP70 with the virus N protein and the raft lipid GM1 was observed within these structures. Immunoprecipitation experiments demonstrated the ability of HSP70 to interact with the virus polymerase complex in lipid-rafts in an ATP-dependent manner. Collectively, these data suggest that RSV may induce cellular changes which allow the recruitment of specific host-cell factors, via lipid-raft membranes, to the polymerase complex.
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Affiliation(s)
- Gaie Brown
- MRC Virology Unit, Institute of Virology, University of Glasgow, Church Street, Glasgow G11 5JR, UK
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Alvarez R, Seal BS. Identification of a truncated nucleoprotein in avian metapneumovirus-infected cells encoded by a second AUG, in-frame to the full-length gene. Virol J 2005; 2:31. [PMID: 15826312 PMCID: PMC1087890 DOI: 10.1186/1743-422x-2-31] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Accepted: 04/12/2005] [Indexed: 11/16/2022] Open
Abstract
Background Avian metapneumoviruses (aMPV) cause an upper respiratory disease with low mortality, but high morbidity primarily in commercial turkeys. There are three types of aMPV (A, B, C) of which the C type is found only in the United States. Viruses related to aMPV include human, bovine, ovine, and caprine respiratory syncytial viruses and pneumonia virus of mice, as well as the recently identified human metapneumovirus (hMPV). The aMPV and hMPV have become the type viruses of a new genus within the Metapneumovirus. The aMPV nucleoprotein (N) amino acid sequences of serotypes A, B, and C were aligned for comparative analysis. Based on predicted antigenicity of consensus protein sequences, five aMPV-specific N peptides were synthesized for development of peptide-antigens and antisera. Results The presence of two aMPV nucleoprotein (N) gene encoded polypeptides was detected in aMPV/C/US/Co and aMPV/A/UK/3b infected Vero cells. Nucleoprotein 1 (N1) encoded from the first open reading frame (ORF) was predicted to be 394 amino acids in length for aMPV/C/US/Co and 391 amino acids in length for aMPV/A/UK/3b with approximate molecular weights of 43.3 kilodaltons and 42.7 kilodaltons, respectively. Nucleoprotein 2 (N2) was hypothesized to be encoded by a second downstream ORF in-frame with ORF1 and encoded a protein predicted to contain 328 amino acids for aMPV/C/US/Co or 259 amino acids for aMPV/A/UK/3b with approximate molecular weights of 36 kilodaltons and 28.3 kilodaltons, respectively. Peptide antibodies to the N-terminal and C-terminal portions of the aMPV N protein confirmed presence of these products in both aMPV/C/US/Co- and aMPV/A/UK/3b-infected Vero cells. N1 and N2 for aMPV/C/US/Co ORFs were molecularly cloned and expressed in Vero cells utilizing eukaryotic expression vectors to confirm identity of the aMPV encoded proteins. Conclusion This is the first reported identification of potential, accessory in-frame N2 ORF gene products among members of the Paramyxoviridae. Genomic sequence analyses of related members of the Pneumovirinae other than aMPV, including human respiratory syncytial virus and bovine respiratory syncytial virus demonstrated the presence of this second potential ORF among these agents.
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Affiliation(s)
- Rene Alvarez
- Southeast Poultry Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Athens, GA 30605, USA
- Present address: Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30605, USA
| | - Bruce S Seal
- Southeast Poultry Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Athens, GA 30605, USA
- Poultry Microbiological Safety Research Unit, ARS, USDA, 950 College Station Rd., Athens, GA 30605, USA
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Mason SW, Lawetz C, Gaudette Y, Dô F, Scouten E, Lagacé L, Simoneau B, Liuzzi M. Polyadenylation-dependent screening assay for respiratory syncytial virus RNA transcriptase activity and identification of an inhibitor. Nucleic Acids Res 2004; 32:4758-67. [PMID: 15356293 PMCID: PMC519107 DOI: 10.1093/nar/gkh809] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
RNA-dependent RNA polymerase from respiratory syncytial virus (RSV) is a multi-subunit ribonucleoprotein (RNP) complex that, in addition to synthesizing the full 15 222 nt viral genomic RNA, is able to synthesize all 10 viral mRNAs. We have prepared crude RNP from RSV-infected HEp-2 cells, based on a method previously used for Newcastle disease virus, and established a novel polyadenylation-dependent capture [poly(A) capture] assay to screen for potential inhibitors of RSV transcriptase activity. In this homogeneous assay, radiolabeled full-length polyadenylated mRNAs produced by the viral RNP are detected through capture on immobilized biotinylated oligo(dT) in a 96-well streptavidin-coated FlashPlate. Possible inhibitors identified with this assay could interfere at any step required for the production of complete RSV mRNAs, including transcription, polyadenylation and, potentially, co-transcriptional guanylylation. A specific inhibitor of RSV transcriptase with antiviral activity was identified through screening of this assay.
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Affiliation(s)
- Stephen W Mason
- Department of Biological Sciences, Boehringer Ingelheim (Canada) Ltd, Laval, Québec H7S 2G5, Canada.
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Chan YP, Koh CL, Lam SK, Wang LF. Mapping of domains responsible for nucleocapsid protein–phosphoprotein interaction of henipaviruses. J Gen Virol 2004; 85:1675-1684. [PMID: 15166452 DOI: 10.1099/vir.0.19752-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Hendra virus (HeV) and Nipah virus (NiV) are members of a new genus, Henipavirus, in the family Paramyxoviridae. Each virus encodes a phosphoprotein (P) that is significantly larger than its counterparts in other known paramyxoviruses. The interaction of this unusually large P with its nucleocapsid protein (N) was investigated in this study by using recombinant full-length and truncated proteins expressed in bacteria and a modified protein-blotting protein-overlay assay. Results from our group demonstrated that the N and P of both viruses were able to form not only homologous, but also heterologous, N–P complexes, i.e. HeV N was able to interact with NiV P and vice versa. Deletion analysis of the N and P revealed that there were at least two independent N-binding sites on P and they resided at the N and C termini, respectively. Similarly, more than one P-binding site was present on N and one of these was mapped to a 29 amino acid (aa) C-terminal region, which on its own was sufficient to interact with the extreme C-terminal 165 aa region of P.
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Affiliation(s)
- Y P Chan
- Institute of Biological Sciences (Genetics), University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - C L Koh
- Institute of Biological Sciences (Genetics), University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - S K Lam
- Department of Medical Microbiology, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - L-F Wang
- CSIRO Livestock Industries, Australian Animal Health Laboratory, PO Bag 24, Geelong, Victoria 3220, Australia
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Stokes HL, Easton AJ, Marriott AC. Chimeric pneumovirus nucleocapsid (N) proteins allow identification of amino acids essential for the function of the respiratory syncytial virus N protein. J Gen Virol 2003; 84:2679-2683. [PMID: 13679601 DOI: 10.1099/vir.0.19370-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The nucleocapsid (N) protein of the pneumovirus respiratory syncytial virus (RSV) is a major structural protein which encapsidates the RNA genome and is essential for replication and transcription of the RSV genome. The N protein of the related virus pneumonia virus of mice (PVM) is functionally unable to replace the RSV N protein in a minigenome replication assay. Using chimeric proteins, in which the immediate C-terminal part of the RSV N protein was replaced with the equivalent region of the PVM N protein, it was shown that six amino acid residues near the C terminus of the N protein (between residues 352-369) are essential for its function in replication and for the ability of the N protein to bind to the viral phosphoprotein, P.
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Affiliation(s)
- H L Stokes
- University of Warwick, Department of Biological Sciences, Coventry CV4 7AL, UK
| | - A J Easton
- University of Warwick, Department of Biological Sciences, Coventry CV4 7AL, UK
| | - A C Marriott
- University of Warwick, Department of Biological Sciences, Coventry CV4 7AL, UK
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15
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Murphy LB, Loney C, Murray J, Bhella D, Ashton P, Yeo RP. Investigations into the amino-terminal domain of the respiratory syncytial virus nucleocapsid protein reveal elements important for nucleocapsid formation and interaction with the phosphoprotein. Virology 2003; 307:143-53. [PMID: 12667822 DOI: 10.1016/s0042-6822(02)00063-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Bacterially expressed nucleocapsid (N) protein, from respiratory syncytial virus (RSV), was used to investigate RNA binding in a modified North-Western blotting protocol. The recombinant protein demonstrated no sequence specificity in binding RNA representing either the antigenomic leader sequence or the nonspecific sequence derived from a plasmid vector. When recombinant N was purified on CsCl gradients, two types of structure, both with densities indicating that they contained RNA, could be visualised by negative-stain electron microscopy. Structures similar to nucleocapsids (NC) from RSV-infected cells were observed, as were ring structures. A small fragment of the N (amino acids 1-92) was all that was required for the production of NC-like structures. Another mutant with an internal deletion could form rings but not NC-like structures. This suggests that this domain (amino acids 121-160) may be important for maintaining helical stability. Further analysis has also identified a potential site in the amino-terminus that may be involved in an interaction with the phosphoprotein. A domain model of the RSV N protein is presented which, similar to that of other paramyxoviruses, supports the idea that the amino-terminus is important for NC assembly.
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Affiliation(s)
- Lindsay B Murphy
- Medical Research Council Virology Unit, Church Street, Glasgow G11 5JR, Scotland, UK
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16
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Murray J, Loney C, Murphy LB, Graham S, Yeo RP. Characterization of monoclonal antibodies raised against recombinant respiratory syncytial virus nucleocapsid (N) protein: identification of a region in the carboxy terminus of N involved in the interaction with P protein. Virology 2001; 289:252-61. [PMID: 11689048 DOI: 10.1006/viro.2001.1150] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To investigate structure and biological properties of the nucleocapsid (N) protein of respiratory syncytial virus (RSV), we have generated a panel of 16 monoclonal antibodies, raised against recombinant N protein, and epitope mapped seven of these to three antigenic sites (Site I aa 16-30; Site II aa 341-350; Site III aa 351-365). Characterization by immunofluorescence and by immunoprecipitation assay demonstrated that a monoclonal antibody to antigenic site I can detect N protein complexed with phospho (P) protein. Antibodies to antigenic sites II and III, which are adjacent to each other near the carboxyl terminus of the N protein, have distinct properties. A site III monoclonal antibody detected N protein in cytoplasmic inclusion bodies and in the cytosol, but not when N was complexed to P protein, while the site II antibody reacted with N protein in the nucleocapsid fraction but did not detect cytosolic N protein. Further investigation into the reactivities of the antibodies after binding of P to N in vitro demonstrated that antigenic sites II and III were blocked by the interaction, indicating an involvement for the carboxy domain of N in the N-P interaction. This was confirmed by the ability of peptides from the carboxy terminus of N to inhibit the N-P interaction in vitro.
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Affiliation(s)
- J Murray
- MRC Virology Unit, Church Street, Glasgow, G11 5JR, Scotland, United Kingdom
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17
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Khattar SK, Yunus AS, Collins PL, Samal SK. Deletion and substitution analysis defines regions and residues within the phosphoprotein of bovine respiratory syncytial virus that affect transcription, RNA replication, and interaction with the nucleoprotein. Virology 2001; 285:253-69. [PMID: 11437660 DOI: 10.1006/viro.2001.0960] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The phosphoprotein (P) of bovine respiratory syncytial virus (BRSV) is a multifunctional protein that plays a central role in transcription and replication of the viral genomic RNA. To investigate the domains and specific residues involved in different activities of the P protein, we generated a total of 22 deletion and 17 point mutants of the P protein. These mutants were characterized using an intracellular BRSV-CAT minigenome replication system for the ability to (1) direct minigenome transcription, (2) direct minigenome replication, and (3) form complexes with nucleocapsid protein (N) and large polymerase protein (L). These studies revealed that all the regions of P protein except amino acids 41-80 are essential for minigenome transcription and replication. Interestingly, amino acids 41-60 appeared to contain sequences that negatively regulate transcription and replication. Analysis of the N- or C-terminal ends indicated that deletion of up to 3 amino acids from the N- or C-terminus completely ablated the replication, while leaving substantial residual transcription. Single amino acid substitutions within the N-terminal 4 or C-terminal 13 amino acids showed that substitution at position 2, 4, 234, 236, 238, 240, or 241 was highly inhibitory to both transcription and replication, whereas substitution at position 3 was highly inhibitory to replication while leaving substantial residual transcription. Substitution of serine residues at the C-terminus indicated that loss of phosphorylation sites did not appear to have any effect on transcription and replication. Coimmunoprecipitation of P-N and P-L complexes with P-specific antiserum revealed that substitution mutations at the N- or C-terminus did not affect binding to N and L proteins, except that substitution mutation at C-terminus position 234, 236, 238, 240, or 241 affected binding to N protein by 10-fold.
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Affiliation(s)
- S K Khattar
- Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, Maryland 20742, USA
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18
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Khattar SK, Yunus AS, Samal SK. Mapping the domains on the phosphoprotein of bovine respiratory syncytial virus required for N-P and P-L interactions using a minigenome system. J Gen Virol 2001; 82:775-779. [PMID: 11257181 DOI: 10.1099/0022-1317-82-4-775] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The interaction of bovine respiratory syncytial virus (BRSV) phosphoprotein (P) with nucleocapsid (N) and large polymerase (L) proteins was investigated using an intracellular BRSV-CAT minigenome replication system. Coimmunoprecipitation assays using P-specific antiserum revealed that the P protein can form complexes with N and L proteins. Deletion mutant analysis of the P protein was performed to identify the regions of P protein that interact with N and L proteins. The results indicate that two independent N-binding sites exist on the P protein: an internal region of 161-180 amino acids and a C-terminal region of 221-241 amino acids. The L-binding site was mapped to a region of P protein encompassing amino acids 121-160. The data suggest that N and L protein binding domains on the P protein do not overlap.
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Affiliation(s)
- Sunil K Khattar
- Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, MD 20742, USA1
| | - Abdul S Yunus
- Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, MD 20742, USA1
| | - Siba K Samal
- Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, MD 20742, USA1
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