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Nevers Q, Scrima N, Glon D, Le Bars R, Decombe A, Garnier N, Ouldali M, Lagaudrière-Gesbert C, Blondel D, Albertini A, Gaudin Y. Properties of rabies virus phosphoprotein and nucleoprotein biocondensates formed in vitro and in cellulo. PLoS Pathog 2022; 18:e1011022. [PMID: 36480574 PMCID: PMC9767369 DOI: 10.1371/journal.ppat.1011022] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 12/20/2022] [Accepted: 11/23/2022] [Indexed: 12/13/2022] Open
Abstract
Rabies virus (RABV) transcription and replication take place within viral factories having liquid properties, called Negri bodies (NBs), that are formed by liquid-liquid phase separation (LLPS). The co-expression of RABV nucleoprotein (N) and phosphoprotein (P) in mammalian cells is sufficient to induce the formation of cytoplasmic biocondensates having properties that are like those of NBs. This cellular minimal system was previously used to identify P domains that are essential for biocondensates formation. Here, we constructed fluorescent versions of N and analyzed by FRAP their dynamics inside the biocondensates formed in this minimal system as well as in NBs of RABV-infected cells using FRAP. The behavior of N appears to be different of P as there was no fluorescence recovery of N proteins after photobleaching. We also identified arginine residues as well as two exposed loops of N involved in condensates formation. Corresponding N mutants exhibited distinct phenotypes in infected cells ranging from co-localization with NBs to exclusion from them associated with a dominant-negative effect on infection. We also demonstrated that in vitro, in crowded environments, purified P as well as purified N0-P complex (in which N is RNA-free) form liquid condensates. We identified P domains required for LLPS in this acellular system. P condensates were shown to associate with liposomes, concentrate RNA, and undergo a liquid-gel transition upon ageing. Conversely, N0-P droplets were disrupted upon incubation with RNA. Taken together, our data emphasize the central role of P in NBs formation and reveal some physicochemical features of P and N0-P droplets relevant for explaining NBs properties such as their envelopment by cellular membranes at late stages of infection and nucleocapsids ejections from the viral factories.
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Affiliation(s)
- Quentin Nevers
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Nathalie Scrima
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Damien Glon
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Romain Le Bars
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Alice Decombe
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Nathalie Garnier
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Malika Ouldali
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Cécile Lagaudrière-Gesbert
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Danielle Blondel
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Aurélie Albertini
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Yves Gaudin
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
- * E-mail:
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2
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Molecular Basis of Functional Effects of Phosphorylation of the C-Terminal Domain of the Rabies Virus P Protein. J Virol 2022; 96:e0011122. [DOI: 10.1128/jvi.00111-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Rabies virus P protein is a multifunctional protein with critical roles in replication and manipulation of host-cell processes, including subversion of immunity. This functional diversity involves interactions of several P protein isoforms with the cell nucleus and microtubules.
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3
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Research Advances on the Interactions between Rabies Virus Structural Proteins and Host Target Cells: Accrued Knowledge from the Application of Reverse Genetics Systems. Viruses 2021; 13:v13112288. [PMID: 34835093 PMCID: PMC8617671 DOI: 10.3390/v13112288] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 11/07/2021] [Accepted: 11/12/2021] [Indexed: 11/17/2022] Open
Abstract
Rabies is a lethal zoonotic disease caused by lyssaviruses, such as rabies virus (RABV), that results in nearly 100% mortality once clinical symptoms appear. There are no curable drugs available yet. RABV contains five structural proteins that play an important role in viral replication, transcription, infection, and immune escape mechanisms. In the past decade, progress has been made in research on the pathogenicity of RABV, which plays an important role in the creation of new recombinant RABV vaccines by reverse genetic manipulation. Here, we review the latest advances on the interaction between RABV proteins in the infected host and the applied development of rabies vaccines by using a fully operational RABV reverse genetics system. This article provides a background for more in-depth research on the pathogenic mechanism of RABV and the development of therapeutic drugs and new biologics.
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4
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Definition of the immune evasion-replication interface of rabies virus P protein. PLoS Pathog 2021; 17:e1009729. [PMID: 34237115 PMCID: PMC8291714 DOI: 10.1371/journal.ppat.1009729] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 07/20/2021] [Accepted: 06/18/2021] [Indexed: 12/24/2022] Open
Abstract
Rabies virus phosphoprotein (P protein) is a multifunctional protein that plays key roles in replication as the polymerase cofactor that binds to the complex of viral genomic RNA and the nucleoprotein (N protein), and in evading the innate immune response by binding to STAT transcription factors. These interactions are mediated by the C-terminal domain of P (PCTD). The colocation of these binding sites in the small globular PCTD raises the question of how these interactions underlying replication and immune evasion, central to viral infection, are coordinated and, potentially, coregulated. While direct data on the binding interface of the PCTD for STAT1 is available, the lack of direct structural data on the sites that bind N protein limits our understanding of this interaction hub. The PCTD was proposed to bind via two sites to a flexible loop of N protein (Npep) that is not visible in crystal structures, but no direct analysis of this interaction has been reported. Here we use Nuclear Magnetic Resonance, and molecular modelling to show N protein residues, Leu381, Asp383, Asp384 and phosphor-Ser389, are likely to bind to a ‘positive patch’ of the PCTD formed by Lys211, Lys214 and Arg260. Furthermore, in contrast to previous predictions we identify a single site of interaction on the PCTD by this Npep. Intriguingly, this site is proximal to the defined STAT1 binding site that includes Ile201 to Phe209. However, cell-based assays indicate that STAT1 and N protein do not compete for P protein. Thus, it appears that interactions critical to replication and immune evasion can occur simultaneously with the same molecules of P protein so that the binding of P protein to activated STAT1 can potentially occur without interrupting interactions involved in replication. These data suggest that replication complexes might be directly involved in STAT1 antagonism. For viruses to infect cells and generate progeny, they must be able to mediate replication, while simultaneously evading the innate immune system. Viruses with small genomes often achieve this through multifunctional proteins that have roles in both replication and immune evasion, such as the phosphoprotein (P protein) of rabies virus. P protein is an essential cofactor in genome replication and transcription, dependent on the well-folded C-terminal domain (PCTD), which binds to the nucleoprotein (N protein) when complexed with RNA. The PCTD can also bind and antagonize signal transducers and activators of transcription (STAT) proteins, that are essential for activating antiviral mechanisms. Here we show using Nuclear Magnetic Resonance spectroscopy and cell-based assays, that the STAT1-binding and N-binding interfaces are proximal but, nevertheless, it appears that the same molecule of PCTD can simultaneously bind STAT1 and N protein. These data suggest that P-protein-STAT1 interaction, critical to immune evasion, can occur without interrupting interactions underlying replication, and so replication complexes might be directly involved in STAT1 antagonism.
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5
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Hossain MA, Larrous F, Rawlinson SM, Zhan J, Sethi A, Ibrahim Y, Aloi M, Lieu KG, Mok YF, Griffin MDW, Ito N, Ose T, Bourhy H, Moseley GW, Gooley PR. Structural Elucidation of Viral Antagonism of Innate Immunity at the STAT1 Interface. Cell Rep 2020; 29:1934-1945.e8. [PMID: 31722208 DOI: 10.1016/j.celrep.2019.10.020] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 07/16/2019] [Accepted: 10/03/2019] [Indexed: 12/24/2022] Open
Abstract
To evade immunity, many viruses express interferon antagonists that target STAT transcription factors as a major component of pathogenesis. Because of a lack of direct structural data, these interfaces are poorly understood. We report the structural analysis of full-length STAT1 binding to an interferon antagonist of a human pathogenic virus. The interface revealed by transferred cross-saturation NMR is complex, involving multiple regions in both the viral and cellular proteins. Molecular mapping analysis, combined with biophysical characterization and in vitro/in vivo functional assays, indicates that the interface is significant in disease caused by a pathogenic field-strain lyssavirus, with critical roles for contacts between the STAT1 coiled-coil/DNA-binding domains and specific regions within the viral protein. These data elucidate the potentially complex nature of IFN antagonist/STAT interactions, and the spatial relationship of protein interfaces that mediate immune evasion and replication, providing insight into how viruses can regulate these essential functions via single multifunctional proteins.
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Affiliation(s)
- Md Alamgir Hossain
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Florence Larrous
- Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC 3010, Australia; Unité Lyssavirus, Epidémiologie et Neuropathologie - CNR de la RAGE, Institut Pasteur, 25 rue du Dr. Roux, 75724 Paris Cedex 15, France
| | - Stephen M Rawlinson
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton Campus, VIC 3800, Australia
| | - Jingyu Zhan
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Ashish Sethi
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Youssef Ibrahim
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Maria Aloi
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton Campus, VIC 3800, Australia
| | - Kim G Lieu
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton Campus, VIC 3800, Australia
| | - Yee-Foong Mok
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Michael D W Griffin
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Naoto Ito
- Laboratory of Zoonotic Diseases, Joint Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Toyoyuki Ose
- Faculty of Advanced Life Science, Hokkaido University, 060-0810 Sapporo, Japan
| | - Hervé Bourhy
- Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC 3010, Australia; Unité Lyssavirus, Epidémiologie et Neuropathologie - CNR de la RAGE, Institut Pasteur, 25 rue du Dr. Roux, 75724 Paris Cedex 15, France
| | - Gregory W Moseley
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC 3010, Australia; Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton Campus, VIC 3800, Australia.
| | - Paul R Gooley
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC 3010, Australia.
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6
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Ogino T, Green TJ. RNA Synthesis and Capping by Non-segmented Negative Strand RNA Viral Polymerases: Lessons From a Prototypic Virus. Front Microbiol 2019; 10:1490. [PMID: 31354644 PMCID: PMC6636387 DOI: 10.3389/fmicb.2019.01490] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 06/14/2019] [Indexed: 12/26/2022] Open
Abstract
Non-segmented negative strand (NNS) RNA viruses belonging to the order Mononegavirales are highly diversified eukaryotic viruses including significant human pathogens, such as rabies, measles, Nipah, and Ebola. Elucidation of their unique strategies to replicate in eukaryotic cells is crucial to aid in developing anti-NNS RNA viral agents. Over the past 40 years, vesicular stomatitis virus (VSV), closely related to rabies virus, has served as a paradigm to study the fundamental molecular mechanisms of transcription and replication of NNS RNA viruses. These studies provided insights into how NNS RNA viruses synthesize 5′-capped mRNAs using their RNA-dependent RNA polymerase L proteins equipped with an unconventional mRNA capping enzyme, namely GDP polyribonucleotidyltransferase (PRNTase), domain. PRNTase or PRNTase-like domains are evolutionally conserved among L proteins of all known NNS RNA viruses and their related viruses belonging to Jingchuvirales, a newly established order, in the class Monjiviricetes, suggesting that they may have evolved from a common ancestor that acquired the unique capping system to replicate in a primitive eukaryotic host. This article reviews what has been learned from biochemical and structural studies on the VSV RNA biosynthesis machinery, and then focuses on recent advances in our understanding of regulatory and catalytic roles of the PRNTase domain in RNA synthesis and capping.
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Affiliation(s)
- Tomoaki Ogino
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH, United States.,Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Todd J Green
- Department of Microbiology, School of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
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7
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Cryo EM structure of the rabies virus ribonucleoprotein complex. Sci Rep 2019; 9:9639. [PMID: 31270364 PMCID: PMC6610074 DOI: 10.1038/s41598-019-46126-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 06/21/2019] [Indexed: 10/26/2022] Open
Abstract
Rabies virus is an important zoonotic pathogen. Its bullet shaped particle contains a helical nucleocapsid. We used cryo-electron tomography and subsequent subtomogram averaging to determine the structure of its ribonucleoprotein. The resulting electron density map allowed for confident fitting of the N-protein crystal structure, indicating that interactions between neighbouring N-proteins are only mediated by N- and C-terminal protruding subdomains (aa 1-27 and aa 355-372). Additional connecting densities, likely stabilizing the ribonucleoprotein complex, are present between neighbouring M-protein densities on the same helical turn and between M- and N-protein densities located on neighbouring helical turns, but not between M-proteins of different turns, as is observed for the related Vesicular stomatitis virus (VSV). This insight into the architecture of the rabies virus nucleocapsid highlights the surprising structural divergence of large biological assemblies even if the building blocks - here exemplified by VSV M- and N-protein - are structurally closely related.
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8
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Alvarez Paggi D, Esperante SA, Salgueiro M, Camporeale G, de Oliveira GAP, Prat Gay G. A conformational switch balances viral RNA accessibility and protection in a nucleocapsid ring model. Arch Biochem Biophys 2019; 671:77-86. [PMID: 31229488 DOI: 10.1016/j.abb.2019.06.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 05/30/2019] [Accepted: 06/19/2019] [Indexed: 12/22/2022]
Abstract
Virus from the Mononegavirales order share common features ranging from virion structure arrangement to mechanisms of replication and transcription. One of them is the way the nucleoprotein (N) wraps and protects the RNA genome from degradation by forming a highly ordered helical nucleocapsid. However, crystal structures from numerous Mononegavirales reveal that binding to the nucleoprotein results in occluded nucleotides that hinder base pairing necessary for transcription and replication. This hints at the existence of alternative conformations of the N protein that would impact on the protein-RNA interface, allowing for transient exposure of the nucleotides without complete RNA release. Moreover, the regulation between the alternative conformations should be finely tuned. Recombinant expression of N from the respiratory syncytial virus form regular N/RNA common among all Mononegavirales, and these constitute an ideal minimal unit for investigating the mechanisms through which these structures protect RNA so efficiently while allowing for partial accessibility during transcription and replication. Neither pH nor high ionic strength could dissociate the RNA but led to irreversible aggregation of the nucleoprotein. Low concentrations of guanidine chloride dissociated the RNA moiety but leading to irreversible aggregation of the protein moiety. On the other hand, high concentrations of urea and long incubation periods were required to remove bound RNA. Both denaturants eventually led to unfolding but converged in the formation of an RNA-free β-enriched intermediate species that remained decameric even at high denaturant concentrations. Although the N-RNA rings interact with the phosphoprotein P, the scaffold of the RNA polymerase complex, this interaction did not lead to RNA dissociation from the rings in vitro. Thus, we have uncovered complex equilibria involving changes in secondary structure of N and RNA loosening, processes that must take place in the context of RNA transcription and replication, whose detailed mechanisms and cellular and viral participants need to be established.
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Affiliation(s)
- D Alvarez Paggi
- Protein Structure-Function and Engineering Laboratory, Fundación Instituto Leloir and IIBBA-CONICET, Argentina.
| | - S A Esperante
- Protein Structure-Function and Engineering Laboratory, Fundación Instituto Leloir and IIBBA-CONICET, Argentina
| | - M Salgueiro
- Protein Structure-Function and Engineering Laboratory, Fundación Instituto Leloir and IIBBA-CONICET, Argentina
| | - G Camporeale
- Protein Structure-Function and Engineering Laboratory, Fundación Instituto Leloir and IIBBA-CONICET, Argentina
| | - G A P de Oliveira
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnêtica Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil and Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA, 22908-0733, USA
| | - G Prat Gay
- Protein Structure-Function and Engineering Laboratory, Fundación Instituto Leloir and IIBBA-CONICET, Argentina.
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9
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Ogino T, Green TJ. Transcriptional Control and mRNA Capping by the GDP Polyribonucleotidyltransferase Domain of the Rabies Virus Large Protein. Viruses 2019; 11:E504. [PMID: 31159413 PMCID: PMC6631705 DOI: 10.3390/v11060504] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 05/24/2019] [Accepted: 05/30/2019] [Indexed: 12/11/2022] Open
Abstract
Rabies virus (RABV) is a causative agent of a fatal neurological disease in humans and animals. The large (L) protein of RABV is a multifunctional RNA-dependent RNA polymerase, which is one of the most attractive targets for developing antiviral agents. A remarkable homology of the RABV L protein to a counterpart in vesicular stomatitis virus, a well-characterized rhabdovirus, suggests that it catalyzes mRNA processing reactions, such as 5'-capping, cap methylation, and 3'-polyadenylation, in addition to RNA synthesis. Recent breakthroughs in developing in vitro RNA synthesis and capping systems with a recombinant form of the RABV L protein have led to significant progress in our understanding of the molecular mechanisms of RABV RNA biogenesis. This review summarizes functions of RABV replication proteins in transcription and replication, and highlights new insights into roles of an unconventional mRNA capping enzyme, namely GDP polyribonucleotidyltransferase, domain of the RABV L protein in mRNA capping and transcription initiation.
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Affiliation(s)
- Tomoaki Ogino
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
| | - Todd J Green
- Department of Microbiology, School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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10
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Webby MN, Sullivan MP, Yegambaram KM, Radjainia M, Keown JR, Kingston RL. A method for analyzing the composition of viral nucleoprotein complexes, produced by heterologous expression in bacteria. Virology 2018; 527:159-168. [PMID: 30529564 DOI: 10.1016/j.virol.2018.11.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Revised: 10/23/2018] [Accepted: 11/22/2018] [Indexed: 12/27/2022]
Abstract
Viral genomes are protected and organized by virally encoded packaging proteins. Heterologous production of these proteins often results in formation of particles resembling the authentic viral capsid or nucleocapsid, with cellular nucleic acids packaged in place of the viral genome. Quantifying the total protein and nucleic acid content of particle preparations is a recurrent biochemical problem. We describe a method for resolving this problem, developed when characterizing particles resembling the Menangle Virus nucleocapsid. The protein content was quantified using the biuret assay, which is largely independent of amino acid composition. Bound nucleic acids were quantified by determining the phosphorus content, using inductively coupled plasma mass spectrometry. Estimates for the amount of RNA packaged within the particles were consistent with the structurally-characterized packaging mechanism. For a bacterially-produced nucleoprotein complex, phosphorus usually provides a unique elemental marker of bound nucleic acids, hence this method of analysis should be routinely applicable.
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Affiliation(s)
- Melissa N Webby
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Matthew P Sullivan
- School of Chemical Sciences, University of Auckland, Auckland, New Zealand
| | | | - Mazdak Radjainia
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Jeremy R Keown
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Richard L Kingston
- School of Biological Sciences, University of Auckland, Auckland, New Zealand.
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11
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Asymmetric Trimeric Ring Structure of the Nucleocapsid Protein of Tospovirus. J Virol 2017; 91:JVI.01002-17. [PMID: 28768868 DOI: 10.1128/jvi.01002-17] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 07/27/2017] [Indexed: 01/09/2023] Open
Abstract
Tomato spotted wilt virus (TSWV), belonging to the genus Tospovirus of the family Bunyaviridae, causes significant economic damage to several vegetables and ornamental plants worldwide. Similar to those of all other negative-strand RNA viruses, the nucleocapsid (N) protein plays very important roles in its viral life cycle. N proteins protect genomic RNAs by encapsidation and form a viral ribonucleoprotein complex (vRNP) with some RNA-dependent RNA polymerases. Here we show the crystal structure of the N protein from TSWV. Protomers of TSWV N proteins consist of three parts: the N arm, C arm, and core domain. Unlike N proteins of other negative-strand RNA viruses, the TSWV N protein forms an asymmetric trimeric ring. To form the trimeric ring, the N and C arms of the N protein interact with the core domains of two adjacent N proteins. By solving the crystal structures of the TSWV N protein with nucleic acids, we showed that an inner cleft of the asymmetric trimeric ring is an RNA-binding site. These characteristics are similar to those of N proteins of other viruses of the family Bunyaviridae Based on these observations, we discuss possibilities of a TSWV encapsidation model.IMPORTANCE Tospoviruses cause significant crop losses throughout the world. Particularly, TSWV has an extremely wide host range (>1,000 plant species, including dicots and monocots), and worldwide losses are estimated to be in excess of $1 billion annually. Despite such importance, no proteins of tospoviruses have been elucidated so far. Among TSWV-encoded proteins, the N protein is required for assembling the viral genomic RNA into the viral ribonucleoprotein (vRNP), which is involved in various steps of the life cycle of these viruses, such as RNA replication, virus particle formation, and cell-to-cell movement. This study revealed the structure of the N protein, with or without nucleic acids, of TSWV as the first virus of the genus Tospovirus, so it completed our view of the N proteins of the family Bunyaviridae.
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12
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Gubala A, Walsh S, McAllister J, Weir R, Davis S, Melville L, Mitchell I, Bulach D, Gauci P, Skvortsov A, Boyle D. Identification of very small open reading frames in the genomes of Holmes Jungle virus, Ord River virus, and Wongabel virus of the genus Hapavirus, family Rhabdoviridae. Evol Bioinform Online 2017; 13:1176934317713484. [PMID: 28747815 PMCID: PMC5510769 DOI: 10.1177/1176934317713484] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 05/05/2017] [Indexed: 12/11/2022] Open
Abstract
Viruses of the family Rhabdoviridae infect a broad range of hosts from a variety of ecological and geographical niches, including vertebrates, arthropods, and plants. The arthropod-transmitted members of this family display considerable genetic diversity and remarkable genomic flexibility that enable coding for various accessory proteins in different locations of the genome. Here, we describe the genome of Holmes Jungle virus, isolated from Culex annulirostris mosquitoes collected in northern Australia, and make detailed comparisons with the closely related Ord River and Wongabel viruses, with a focus on identifying very small open reading frames (smORFs) in their genomes. This is the first systematic prediction of smORFs in rhabdoviruses, emphasising the intricacy of the rhabdovirus genome and the knowledge gaps. We speculate that these smORFs may be of importance to the life cycle of the virus in the arthropod vector.
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Affiliation(s)
- Aneta Gubala
- Land Division, Defence Science and Technology Group, Fishermans Bend, VIC, Australia
| | - Susan Walsh
- Berrimah Veterinary Laboratories, Department of Primary Industry and Fisheries, Northern Territory Government, Berrimah, NT, Australia
| | - Jane McAllister
- Land Division, Defence Science and Technology Group, Fishermans Bend, VIC, Australia
| | - Richard Weir
- Berrimah Veterinary Laboratories, Department of Primary Industry and Fisheries, Northern Territory Government, Berrimah, NT, Australia
| | - Steven Davis
- Berrimah Veterinary Laboratories, Department of Primary Industry and Fisheries, Northern Territory Government, Berrimah, NT, Australia
| | - Lorna Melville
- Berrimah Veterinary Laboratories, Department of Primary Industry and Fisheries, Northern Territory Government, Berrimah, NT, Australia
| | - Ian Mitchell
- Land Division, Defence Science and Technology Group, Fishermans Bend, VIC, Australia
| | - Dieter Bulach
- Australian Animal Health Laboratory, Commonwealth Scientific and Industrial Research Organisation, Geelong, VIC, Australia
| | - Penny Gauci
- Land Division, Defence Science and Technology Group, Fishermans Bend, VIC, Australia
| | - Alex Skvortsov
- Land Division, Defence Science and Technology Group, Fishermans Bend, VIC, Australia
| | - David Boyle
- Australian Animal Health Laboratory, Commonwealth Scientific and Industrial Research Organisation, Geelong, VIC, Australia
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13
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Nguyen TD, Takasuka H, Kaku Y, Inoue S, Nagamune T, Kawahara M. Engineering a growth sensor to select intracellular antibodies in the cytosol of mammalian cells. J Biosci Bioeng 2017; 124:125-132. [PMID: 28319021 DOI: 10.1016/j.jbiosc.2017.02.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 02/24/2017] [Indexed: 02/02/2023]
Abstract
Intracellular antibodies (intrabodies) are expected to function as therapeutics as well as tools for elucidating in vivo function of proteins. In this study, we propose a novel intrabody selection method in the cytosol of mammalian cells by utilizing a growth signal, induced by the interaction of the target antigen and an scFv-c-kit growth sensor. Here, we challenge this method to select specific intrabodies against rabies virus nucleoprotein (RV-N) for the first time. As a result, we successfully select antigen-specific intrabodies from a naïve synthetic library using phage panning followed by our growth sensor-based intracellular selection method, demonstrating the feasibility of the method. Additionally, we succeed in improving the response of the growth sensor by re-engineering the linker region of its construction. Collectively, the described selection method utilizing a growth sensor may become a highly efficient platform for selection of functional intrabodies in the future.
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Affiliation(s)
- Thuy Duong Nguyen
- Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Hitoshi Takasuka
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Yoshihiro Kaku
- Department of Veterinary Science, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku, Tokyo 162-8640, Japan
| | - Satoshi Inoue
- Department of Veterinary Science, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku, Tokyo 162-8640, Japan
| | - Teruyuki Nagamune
- Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan; Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Masahiro Kawahara
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
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Tursunov K, Begaliyeva A, Ingirbay B, Mukanov K, Ramanculov E, Shustov A, Mukantayev K. Cloning and expression of fragment of the rabies virus nucleoprotein gene in Escherichia coli and evaluation of antigenicity of the expression product. IRANIAN JOURNAL OF VETERINARY RESEARCH 2017; 18:36-42. [PMID: 28588631 PMCID: PMC5454577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 10/19/2016] [Accepted: 11/13/2016] [Indexed: 06/07/2023]
Abstract
Rabies virus nucleoprotein (N protein) encapsidates genomic RNA of the virus and forms the viral ribonucleoprotein complex. These N proteins represent highly organized structures which activate proliferation of B cells and production antibodies against the N protein. In addition to the B cell, the rabies virus N protein has been shown to induce potent T helper cell responses resulting in a long-lasting and strong humoral immune response. Rabies virus N protein is a molecular target of choice for development of tools to diagnose acute rabies infection. We produced a recombinant immune reactive C-terminal fragment of the rabies virus N protein which contains an antigenic determinant located between positions 360-389. Synthetic gene encoding the N protein was cloned into an expression plasmid to produce the recombinant antigen in Escherichiacoli cells BL21 (DE3). SDS-PAGE showed presence of the product with expected molecular weight (44 kDa). The recombinant fragment of the N protein efficiently recognized antibodies in sera from mice immunized with an inactivated rabies virus. Thus produced recombinant antigen of the rabies virus N protein can be used in an enzyme-linked immunosorbent assay (ELISA) for diagnosis of the rabies infection.
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Affiliation(s)
- K. Tursunov
- Department of Immunochemistry and Immunobiotechnology, National Center for Biotechnology, Astana 010000, Kazakhstan
| | - A. Begaliyeva
- Department of Immunochemistry and Immunobiotechnology, National Center for Biotechnology, Astana 010000, Kazakhstan
| | - B. Ingirbay
- Department of Immunochemistry and Immunobiotechnology, National Center for Biotechnology, Astana 010000, Kazakhstan
| | - K. Mukanov
- Department of Immunochemistry and Immunobiotechnology, National Center for Biotechnology, Astana 010000, Kazakhstan
| | - E. Ramanculov
- National Center for Biotechnology, Astana 010000, Kazakhstan
| | - A. Shustov
- Department of Genetic Engineering, National Center for Biotechnology, Astana 010000, Kazakhstan
| | - K. Mukantayev
- Department of Immunochemistry and Immunobiotechnology, National Center for Biotechnology, Astana 010000, Kazakhstan
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15
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Jamin M, Yabukarski F. Nonsegmented Negative-Sense RNA Viruses-Structural Data Bring New Insights Into Nucleocapsid Assembly. Adv Virus Res 2016; 97:143-185. [PMID: 28057258 DOI: 10.1016/bs.aivir.2016.09.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Viruses with a nonsegmented negative-sense RNA genome (NNVs) include important human pathogens as well as life-threatening zoonotic viruses. These viruses share a common RNA replication complex, including the genomic RNA and three proteins, the nucleoprotein (N), the phosphoprotein (P), and the RNA-dependent RNA polymerase (L). During genome replication, the RNA polymerase complex first synthesizes positive-sense antigenomes, which in turn serve as template for the production of negative-sense progeny genomes. These newly synthesized antigenomic and genomic RNAs must be encapsidated by N, and the source of soluble, RNA-free N, competent for the encapsidation is a complex between N and P, named the N0-P complex. In this review, we summarize recent progress made in the structural characterization of the different components of this peculiar RNA polymerase machinery. We discuss common features and replication strategies and highlight idiosyncrasies encountered in different viruses, along with the key role of the dual ordered/disordered architecture of protein components and the dynamics of the viral polymerase machinery. In particular, we focus on the N0-P complex and its role in the nucleocapsid assembly process. These new results provide evidence that the mechanism of NC assembly is conserved between the different families and thus support a divergent evolution from a common ancestor. In addition, the successful inhibition of infection due to different NNVs by peptides derived from P suggests that the mechanism of NC assembly is a potential target for antiviral development.
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Affiliation(s)
- M Jamin
- Institut de Biologie Structurale (IBS), CEA, CNRS, University Grenoble Alpes, Grenoble, France.
| | - F Yabukarski
- Institut de Biologie Structurale (IBS), CEA, CNRS, University Grenoble Alpes, Grenoble, France
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16
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Oligomerization of Mumps Virus Phosphoprotein. J Virol 2015; 89:11002-10. [PMID: 26311887 DOI: 10.1128/jvi.01719-15] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2015] [Accepted: 08/17/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The mumps virus (MuV) genome encodes a phosphoprotein (P) that is important for viral RNA synthesis. P forms the viral RNA-dependent RNA polymerase with the large protein (L). P also interacts with the viral nucleoprotein (NP) and self-associates to form a homotetramer. The P protein consists of three domains, the N-terminal domain (P(N)), the oligomerization domain (P(O)), and the C-terminal domain (P(C)). While P(N) is known to relax the NP-bound RNA genome, the roles of P(O) and P(C) are not clear. In this study, we investigated the roles of P(O) and P(C) in viral RNA synthesis using mutational analysis and a minigenome system. We found that P(N) and P(C) functions can be trans-complemented. However, this complementation requires P(O), indicating that P(O) is essential for P function. Using this trans-complementation system, we found that P forms parallel dimers (P(N) to P(N) and P(C) to P(C)). Furthermore, we found that residues R231, K238, K253, and K260 in P(O) are critical for P's functions. We identified P(C) to be the domain that interacts with L. These results provide structure-function insights into the role of MuV P. IMPORTANCE MuV, a paramyxovirus, is an important human pathogen. The P protein of MuV is critical for viral RNA synthesis. In this work, we established a novel minigenome system that allows the domains of P to be complemented in trans. Using this system, we confirmed that MuV P forms parallel dimers. An understanding of viral RNA synthesis will allow the design of better vaccines and the development of antivirals.
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17
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Wang L, Wu H, Tao X, Li H, Rayner S, Liang G, Tang Q. Genetic and evolutionary characterization of RABVs from China using the phosphoprotein gene. Virol J 2013; 10:14. [PMID: 23294868 PMCID: PMC3548735 DOI: 10.1186/1743-422x-10-14] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 12/07/2012] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND While the function of the phosphoprotein (P) gene of the rabies virus (RABV) has been well studied in laboratory adapted RABVs, the genetic diversity and evolution characteristics of the P gene of street RABVs remain unclear. The objective of the present study was to investigate the mutation and evolution of P genes in Chinese street RABVs. RESULTS The P gene of 77 RABVs from brain samples of dogs and wild animals collected in eight Chinese provinces through 2003 to 2008 were sequenced. The open reading frame (ORF) of the P genes was 894 nucleotides (nt) in length, with 85-99% (80-89%) amino acid (nucleotide) identity compared with the laboratory RABVs and vaccine strains. Phylogenetic analysis based on the P gene revealed that Chinese RABVs strains could be divided into two distinct clades, and several RABV variants were found to co circulating in the same province. Two conserved (CD1, 2) and two variable (VD1, 2) domains were identified by comparing the deduced primary sequences of the encoded P proteins. Two sequence motifs, one believed to confer binding to the cytoplasmic dynein light chain LC8 and a lysine-rich sequence were conserved throughout the Chinese RABVs. In contrast, the isolates exhibited lower conservation of one phosphate acceptor and one internal translation initiation site identified in the P protein of the rabies challenge virus standard (CVS) strain. Bayesian coalescent analysis showed that the P gene in Chinese RABVs have a substitution rate (3.305x10(-4) substitutions per site per year) and evolution history (592 years ago) similar to values for the glycoprotein (G) and nucleoprotein (N) reported previously. CONCLUSION Several substitutions were found in the P gene of Chinese RABVs strains compared to the laboratory adapted and vaccine strains, whether these variations could affect the biological characteristics of Chinese RABVs need to be further investigated. The substitution rate and evolution history of P gene is similar to G and N gene, combine the topology of phylogenetic tree based on the P gene is similar to the G and N gene trees, indicate that the P, G and N genes are equally valid for examining the phylogenetics of RABVs.
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Affiliation(s)
- Lihua Wang
- State Key Laboratory for Infectious Disease Prevention and Control, Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, 155 Changbai St., Changping Dist, Beijing, 102206, China
| | - Hui Wu
- State Key Laboratory for Infectious Disease Prevention and Control, Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, 155 Changbai St., Changping Dist, Beijing, 102206, China
| | - Xiaoyan Tao
- State Key Laboratory for Infectious Disease Prevention and Control, Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, 155 Changbai St., Changping Dist, Beijing, 102206, China
| | - Hao Li
- State Key Laboratory for Infectious Disease Prevention and Control, Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, 155 Changbai St., Changping Dist, Beijing, 102206, China
| | - Simon Rayner
- State Key Laboratory for Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Hubei, 430071, China
| | - Guodong Liang
- State Key Laboratory for Infectious Disease Prevention and Control, Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, 155 Changbai St., Changping Dist, Beijing, 102206, China
| | - Qing Tang
- State Key Laboratory for Infectious Disease Prevention and Control, Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, 155 Changbai St., Changping Dist, Beijing, 102206, China
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18
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Abstract
The family Rhabdoviridae has a non-segmented single stranded negative-sense RNA and its genome ranges in size from approximately 11 kb to almost 16 kb. It is one of the most ecologically diverse families of RNA viruses with members infecting a wide range of organisms. The five structural protein genes are arranged in the same linear order (3'-N-P-M-G-L-5') and may be interspersed with one more additional accessory gene. For many years, a full of knowledge of the rhabdoviridae has been established on extensive studies of two kinds of prototype viruses; vesicular stomatitis virus (VSV) and rabies virus (RABV). Among them, the genus Lyssavirus includes RABV and rabies-related viruses naturally infect mammals and chiropterans via bite-exposure by rabid animals and finally cause fatal encephalitis. In this review, we describe the sketch of the various virological features of the Rhabdoviridae, especially focusing on VSV and RABV.
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19
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Structural insights into the rhabdovirus transcription/replication complex. Virus Res 2011; 162:126-37. [PMID: 21963663 DOI: 10.1016/j.virusres.2011.09.025] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 09/17/2011] [Accepted: 09/18/2011] [Indexed: 12/25/2022]
Abstract
The rhabdoviruses have a non-segmented single stranded negative-sense RNA genome. Their multiplication in a host cell requires three viral proteins in addition to the viral RNA genome. The nucleoprotein (N) tightly encapsidates the viral RNA, and the N-RNA complex serves as the template for both transcription and replication. The viral RNA-dependent RNA polymerase is a two subunit complex that consists of a large subunit, L, and a non-catalytic cofactor, the phosphoprotein, P. P also acts as a chaperone of nascent RNA-free N by forming a N(0)-P complex that prevents N from binding to cellular RNAs and from polymerizing in the absence of RNA. Here, we discuss the recent molecular and structural studies of individual components and multi-molecular complexes that are involved in the transcription/replication complex of these viruses with regard to their implication in viral transcription and replication.
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20
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Abstract
Rabies virus (RABV) is a negative-stranded RNA virus. Its genome is tightly encapsidated by the viral nucleoprotein (N) and this RNA-N complex is the template for transcription and replication by the viral RNA-dependent RNA polymerase (L) and its cofactor, the phosphoprotein (P). We present molecular, structural, and cellular aspects of RABV transcription and replication. We first summarize the characteristics and molecular biology of both RNA synthesis processes. We then discuss biochemical and structural data on the viral proteins (N, P, and L) and their interactions with regard to their role in viral transcription and replication. Finally, we review evidence that rabies viral transcription and replication take place in cytoplasmic inclusion bodies formed in RABV-infected cells and discuss the role of this cellular compartmentalization.
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21
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Abstract
Rabies is among the longest known and most dangerous and feared infectious diseases for humans and animals and still is responsible for tenth of thousands of human deaths per year. The rabies virus (RABV) is a rather atypical member of the Rhabdoviridae family as it has completely adapted during evolution to warm-blooded hosts and is directly transmitted between them, whereas most other rhabdoviruses are transmitted by insect vectors. The virus is also unique with respect to its extremely broad host species range and a very narrow host organ range, namely its strict neurotropism. It is becoming increasingly clear that the host innate immune system, particularly the type I interferon system, and the viral counteractions profoundly shape this virus-host relationship. In the past few years, exciting new insight was obtained on how viruses are sensed by innate immune receptors, how the downstream signaling networks for activation of interferon are working, and how viruses can interfere with the system. While RABV 5'-triphosphate RNAs were identified as the major pathogen-associated molecular pattern sensed by cytoplasmic RIG-I-like receptors (RLR), the RABV phosphoprotein (P) has emerged as a potent multifunctional antagonist able to counteract the signaling cascades leading to transcriptional activation of interferon genes as well as interferon signaling pathways, thereby limiting expression of antiviral and immune-stimulatory genes.
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Affiliation(s)
- Martina Rieder
- Max von Pettenkofer Institute and Gene Center, Ludwig-Maximilians-University Munich, Munich, Germany
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22
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Cleveland SB, Davies J, McClure MA. A bioinformatics approach to the structure, function, and evolution of the nucleoprotein of the order mononegavirales. PLoS One 2011; 6:e19275. [PMID: 21559282 PMCID: PMC3086907 DOI: 10.1371/journal.pone.0019275] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Accepted: 04/01/2011] [Indexed: 01/09/2023] Open
Abstract
The goal of this Bioinformatic study is to investigate sequence conservation in relation to evolutionary function/structure of the nucleoprotein of the order Mononegavirales. In the combined analysis of 63 representative nucleoprotein (N) sequences from four viral families (Bornaviridae, Filoviridae, Rhabdoviridae, and Paramyxoviridae) we predict the regions of protein disorder, intra-residue contact and co-evolving residues. Correlations between location and conservation of predicted regions illustrate a strong division between families while high- lighting conservation within individual families. These results suggest the conserved regions among the nucleoproteins, specifically within Rhabdoviridae and Paramyxoviradae, but also generally among all members of the order, reflect an evolutionary advantage in maintaining these sites for the viral nucleoprotein as part of the transcription/replication machinery. Results indicate conservation for disorder in the C-terminus region of the representative proteins that is important for interacting with the phosphoprotein and the large subunit polymerase during transcription and replication. Additionally, the C-terminus region of the protein preceding the disordered region, is predicted to be important for interacting with the encapsidated genome. Portions of the N-terminus are responsible for N∶N stability and interactions identified by the presence or lack of co-evolving intra-protein contact predictions. The validation of these prediction results by current structural information illustrates the benefits of the Disorder, Intra-residue contact and Compensatory mutation Correlator (DisICC) pipeline as a method for quickly characterizing proteins and providing the most likely residues and regions necessary to target for disruption in viruses that have little structural information available.
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Affiliation(s)
- Sean B Cleveland
- Department of Microbiology and the Center for Computational Biology, Montana State University, Bozeman, Montana, USA.
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23
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Leyrat C, Ribeiro EA, Gérard FCA, Ivanov I, Ruigrok RWH, Jamin M. Structure, interactions with host cell and functions of rhabdovirus phosphoprotein. Future Virol 2011. [DOI: 10.2217/fvl.11.10] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Rabies is an incurable albeit preventable disease that remains an important human health issue, with the number of deaths exceeding 50,000 people each year. Its causative agent, the rabies virus, is a negative-sense RNA virus, the genome of which encodes five proteins. Three of these proteins, the nucleoprotein, the phosphoprotein (P) and the large protein, are required to synthesize viral RNA in an efficient and regulated manner. P plays multiple roles during the transcription and replication of the RNA genome. It acts as a noncatalytic cofactor of the large protein polymerase and it chaperones nucleoprotein. Recent structural characterizations of rabies virus P revealed that P forms elongated and flexible dimers and uncovered the structural basis of its modular organization, revealing the existence of two independent structured domains and two long intrinsically disordered regions. In addition, recent studies also revealed that P interacts with nucleocytoplasmic trafficking carriers and with the host cell cytoskeleton, probably allowing viral components to be transported within the host cell and blocking the innate immune response by inhibiting different steps of the interferon pathway. With multiple binding sites for different viral and cellular partners located in either its structured or disordered regions, P appears to be a flexible ‘hub’ protein that connects viral or cellular proteins and allows their assembly into multimolecular complexes. These new findings shed light on the mechanism of replication of the virus and on the intimate interactions between the virus and its host cell, and will also help to identify new targets for the development of antiviral treatments.
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Affiliation(s)
- Cédric Leyrat
- UMI 3265 UJF-EMBL-CNRS, Unit of Virus Host Cell Interactions, 6 rue Jules Horowitz, 38042 Grenoble Cedex 9, France
| | - Euripedes A Ribeiro
- UMI 3265 UJF-EMBL-CNRS, Unit of Virus Host Cell Interactions, 6 rue Jules Horowitz, 38042 Grenoble Cedex 9, France
| | - Francine CA Gérard
- UMI 3265 UJF-EMBL-CNRS, Unit of Virus Host Cell Interactions, 6 rue Jules Horowitz, 38042 Grenoble Cedex 9, France
| | - Ivan Ivanov
- UMI 3265 UJF-EMBL-CNRS, Unit of Virus Host Cell Interactions, 6 rue Jules Horowitz, 38042 Grenoble Cedex 9, France
| | - Rob WH Ruigrok
- UMI 3265 UJF-EMBL-CNRS, Unit of Virus Host Cell Interactions, 6 rue Jules Horowitz, 38042 Grenoble Cedex 9, France
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Marschalek A, Drechsel L, Conzelmann KK. The importance of being short: the role of rabies virus phosphoprotein isoforms assessed by differential IRES translation initiation. Eur J Cell Biol 2011; 91:17-23. [PMID: 21397980 DOI: 10.1016/j.ejcb.2011.01.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Accepted: 01/23/2011] [Indexed: 10/18/2022] Open
Abstract
The rabies virus (RV) phosphoprotein P is a multifunctional protein involved in viral RNA synthesis and in counteracting host innate immune responses. We have previously shown that RV P gene expression levels can be regulated by using picornavirus internal ribosome entry site (IRES) elements. Here we exploited a particular feature of the foot-and-mouth disease virus (FMDV) IRES, namely, preferential initiation at a downstream initiation codon, to address the role of N-terminally truncated RV phosphoproteins usually generated in RV-infected cells through ribosomal leaky scanning. Recombinant RVs in which P synthesis was directed by the poliovirus or FMDV IRES produced full-length P (P1) or a truncated form (P2), as the dominant product, respectively. While the P2 overexpressing virus showed attenuated growth in interferon-incompetent cells, it was superior to the P1 overexpressing virus in preventing expression of host interferon-stimulated genes. This indicates that in RV infected cells the availability of the truncated P2 protein is critical for viral resistance to interferon.
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Affiliation(s)
- Adriane Marschalek
- Max von Pettenkofer-Institute & Gene Center, Ludwig-Maximilians-University Munich, Feodor-Lynen-Strasse 25, Munich, Germany
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25
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Genomics and structure/function studies of Rhabdoviridae proteins involved in replication and transcription. Antiviral Res 2010; 87:149-61. [DOI: 10.1016/j.antiviral.2010.02.322] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Accepted: 02/20/2010] [Indexed: 01/19/2023]
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26
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Sarkar A, Chattopadhyay S, Cox R, Luo M, Banerjee AK. Structural and functional properties of the vesicular stomatitis virus nucleoprotein-RNA complex as revealed by proteolytic digestion. Virology 2010; 401:61-9. [PMID: 20206958 DOI: 10.1016/j.virol.2010.02.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Revised: 01/05/2010] [Accepted: 02/09/2010] [Indexed: 12/31/2022]
Abstract
To gain insight into the structural and functional properties of the vesicular stomatitis virus nucleocapsid-RNA complex (vN-RNA), we analyzed it by treatment with proteolytic enzymes. Chymotrypsin treatment to the vN-RNA results in complete digestion of the C-terminal 86 amino acids of the N protein. The residual chymotrypsin resistant vN-RNA complex (vDeltaN-RNA) carrying N-terminal 336 amino acids of the N protein (DeltaN) was inactive in transcription. The DeltaN protein retained its capability to protect the genomic RNA from nuclease digestion but failed to interact to the P protein. Interestingly, addition of excess amount of P protein rendered the vN-RNA complex resistant to the chymotrypsin digestion. Finally, our data revealed that the recombinant N-RNA complex purified from bacteria (bN-RNA) is resistant to chymotrypsin digestion, suggesting that the C-terminal unstructured domain (C-loop) remains inaccessible to protease digestion. Detailed comparative analyses of the vN-RNA and vDeltaN-RNA are discussed.
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Affiliation(s)
- Anindya Sarkar
- Department of Molecular Genetics, Section of Virology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
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27
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Hock M, Kraus I, Schoehn G, Jamin M, Andrei-Selmer C, Garten W, Weissenhorn W. RNA induced polymerization of the Borna disease virus nucleoprotein. Virology 2010; 397:64-72. [DOI: 10.1016/j.virol.2009.11.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Revised: 10/29/2009] [Accepted: 11/10/2009] [Indexed: 10/20/2022]
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28
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Deciphering the function of lactococcal phage ul36 Sak domains. J Struct Biol 2009; 170:462-9. [PMID: 20036743 DOI: 10.1016/j.jsb.2009.12.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Revised: 12/14/2009] [Accepted: 12/19/2009] [Indexed: 11/20/2022]
Abstract
Virulent phages are responsible for milk fermentation failures in the dairy industry, due to their ability to infect starter cultures containing strains of Lactococcus lactis. Single-strand annealing proteins (SSAPs) have been found in several lactococcal phages, among which Sak in the phage ul36. Sak has been recently shown to be a functional homolog of the human protein RAD52, involved in homologous recombination. A comparison between full-length Sak and its N- and C-terminal domains was carried out to elucidate functional characteristics of each domain. We performed HPLC-SEC, AFM and SPR experiments to evaluate oligomerization states and compare the affinities to DNA. We have shown that the N-terminal domain (1-171) is essential and sufficient for oligomerization and binding to DNA, while the C-terminal domain (172-252) does not bind DNA nor oligomerize. Modelisation of Sak N-terminal domain suggests that DNA may bind a positively charged crevice that runs external to the ring. Annealing and stimulation of RecA strand exchange indicate that only the N-terminal domain is capable of single-strand annealing and both domains do not stimulate the RecA strand exchange reaction. We propose that Sak N-terminus is involved in DNA binding and annealing while the C-terminus may serve to contact Sak partners.
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29
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Abstract
Mokola virus (MOKV) is a nonsegmented, negative-sense RNA virus that belongs to the Lyssavirus genus and Rhabdoviridae family. MOKV phosphoprotein P is an essential component of the replication and transcription complex and acts as a cofactor for the viral RNA-dependent RNA polymerase. P recruits the viral polymerase to the nucleoprotein-bound viral RNA (N-RNA) via an interaction between its C-terminal domain and the N-RNA complex. Here we present a structure for this domain of MOKV P, obtained by expression of full-length P in Escherichia coli, which was subsequently truncated during crystallization. The structure has a high degree of homology with P of rabies virus, another member of Lyssavirus genus, and to a lesser degree with P of vesicular stomatitis virus (VSV), a member of the related Vesiculovirus genus. In addition, analysis of the crystal packing of this domain reveals a potential binding site for the nucleoprotein N. Using both site-directed mutagenesis and yeast two-hybrid experiments to measure P-N interaction, we have determined the relative roles of key amino acids involved in this interaction to map the region of P that binds N. This analysis also reveals a structural relationship between the N-RNA binding domain of the P proteins of the Rhabdoviridae and the Paramyxoviridae.
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30
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Ribeiro EDA, Leyrat C, Gérard FCA, Albertini AAV, Falk C, Ruigrok RWH, Jamin M. Binding of rabies virus polymerase cofactor to recombinant circular nucleoprotein-RNA complexes. J Mol Biol 2009; 394:558-75. [PMID: 19781554 DOI: 10.1016/j.jmb.2009.09.042] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 09/11/2009] [Accepted: 09/16/2009] [Indexed: 11/19/2022]
Abstract
In rabies virus, the attachment of the L polymerase (L) to the viral nucleocapsids (NCs)-a nucleoprotein (N)-RNA complex that serves as template for RNA transcription and replication-is mediated by the polymerase cofactor, the phosphoprotein (P). P forms dimers (P(2)) that bind through their C-terminal domains (P(CTD)) to the C-terminal region of the N. Recombinant circular N(m)-RNA complexes containing 9 to 12 protomers of N (hereafter, the subscript m denotes the number of N protomers) served here as model systems for studying the binding of P to NC-like N(m)-RNA complexes. Titration experiments show that there are only two equivalent and independent binding sites for P dimers on the N(m)-RNA rings and that each P dimer binds through a single P(CTD). A dissociation constant in the nanomolar range (160+/-20 nM) was measured by surface plasmon resonance, indicating a strong interaction between the two partners. Small-angle X-ray scattering (SAXS) data and small-angle neutron scattering data showed that binding of two P(CTD) had almost no effect on the size and shape of the N(m)-RNA rings, whereas binding of two P(2) significantly increased the size of the complexes. SAXS data and molecular modeling were used to add flexible loops (N(NTD) loop, amino acids 105-118; N(CTD) loop, amino acids 376-397) missing in the recently solved crystal structure of the circular N(11)-RNA complex and to build a model for the N(10)-RNA complex. Structural models for the N(m)-RNA-(P(CTD))(2) complexes were then built by docking the known P(CTD) structure onto the completed structures of the circular N(10)-RNA and N(11)-RNA complexes. A multiple-stage flexible docking procedure was used to generate decoys, and SAXS and biochemical data were used for filtering the models. In the refined model, the P(CTD) is bound to the C-terminal top of one N protomer (N(i)), with the C-terminal helix (alpha(6)) of P(CTD) lying on helix alpha(14) of N(i). By an induced-fit mechanism, the N(CTD) loop of the same protomer (N(i)) and that of the adjacent one (N(i)(-1)) mold around the P(CTD), making extensive protein-protein contacts that could explain the strong affinity of P for its template. The structural model is in agreement with available biochemical data and provides new insights on the mechanism of attachment of the polymerase complex to the NC template.
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31
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Peptides that mimic the amino-terminal end of the rabies virus phosphoprotein have antiviral activity. J Virol 2009; 83:10808-20. [PMID: 19706704 DOI: 10.1128/jvi.00977-09] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
We wanted to develop a therapeutic approach against rabies disease by targeting the lyssavirus transcription/replication complex. Because this complex (nucleoprotein N-RNA template processed by the L polymerase and its cofactor, the phosphoprotein P) is similar to that of other negative-strand RNA viruses, we aimed to design broad-spectrum antiviral drugs that could be used as a complement to postexposure vaccination and immunotherapy. Recent progress in understanding the structure/function of the rabies virus P, N, and L proteins predicts that the amino-terminal end of P is an excellent target for destabilizing the replication complex because it interacts with both L (for positioning onto the N-RNA template) and N (for keeping N soluble, as needed for viral RNA encapsidation). Thus, peptides mimicking various lengths of the amino-terminal end of P have been evaluated, as follows: (i) for binding properties to the N-P-L partners by the two-hybrid method; (ii) for their capacity to inhibit the transcription/replication of a rabies virus minigenome encoding luciferase in BHK-21-T7 cells; and (iii) for their capacity to inhibit rabies virus infection of BHK-21-T7 cells and of two derivatives of the neuronal SK-N-SH cell line. Peptides P60 and P57 (the first 60 and first 57 NH2 residues of P, respectively) exhibited a rapid, strong, and long-lasting inhibitory potential on luciferase expression (>95% from 24 h to 55 h). P42 was less efficient in its inhibition level (75% for 18 to 30 h) and duration (40% after 48 h). The most promising peptides were synthesized in tandem with the Tat sequence, allowing cell penetration. Their inhibitory effects were observed on BHK-21-T7 cells infected with rabies virus and Lagos bat virus but not with vesicular stomatitis virus. In neuronal cells, a significant inhibition of both nucleocapsid inclusions and rabies virus release was observed.
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32
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Crystal structure of the Borna disease virus matrix protein (BDV-M) reveals ssRNA binding properties. Proc Natl Acad Sci U S A 2009; 106:3710-5. [PMID: 19237566 DOI: 10.1073/pnas.0808101106] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Borna disease virus (BDV) is a neurotropic enveloped RNA virus that causes a noncytolytic, persistent infection of the central nervous system in mammals. BDV belongs to the order Mononegavirales, which also includes the negative-strand RNA viruses (NSVs) Ebola, Marburg, vesicular stomatitis, rabies, mumps, and measles. BDV-M, the matrix protein (M-protein) of BDV, is the smallest M-protein (16.2 kDa) among the NSVs. M-proteins play a critical role in virus assembly and budding, mediating the interaction between the viral capsid, envelope, and glycoprotein spikes, and are as such responsible for the structural stability and individual form of virus particles. Here, we report the 3D structure of BDV-M, a full-length M-protein structure from a nonsegmented RNA NSV. The BDV-M monomer exhibits structural similarity to the N-terminal domain of the Ebola M-protein (VP40), while the surface charge of the tetramer provides clues to the membrane association of BDV-M. Additional electron density in the crystal reveals the presence of bound nucleic acid, interpreted as cytidine-5'-monophosphate. The heterologously expressed BDV-M copurifies with and protects ssRNA oligonucleotides of a median length of 16 nt taken up from the expression host. The results presented here show that BDV-M would be able to bind RNA and lipid membranes simultaneously, expanding the repertoire of M-protein functionalities.
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33
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Lacroix M, Dumestre-Pérard C, Schoehn G, Houen G, Cesbron JY, Arlaud GJ, Thielens NM. Residue Lys57 in the collagen-like region of human L-ficolin and its counterpart Lys47 in H-ficolin play a key role in the interaction with the mannan-binding lectin-associated serine proteases and the collectin receptor calreticulin. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2009; 182:456-65. [PMID: 19109177 DOI: 10.4049/jimmunol.182.1.456] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
L- and H-ficolins are serum oligomeric defense proteins consisting of a collagen-like region and a fibrinogen-like recognition domain that bind to pathogen- and apoptotic cell-associated molecular patterns. They share with mannan-binding lectin (MBL) the ability to associate with MBL-associated serine proteases (MASP)-1, -2, -3, and protein MAp19 and to trigger the lectin complement pathway through MASP-2 activation. Recent studies have revealed the essential role of Lys(55) in the collagenous region of MBL in the interaction with the MASPs and calreticulin (CRT). To test the possible involvement of the homologous residues Lys(57) of L-ficolin and Lys(47) of H-ficolin, point mutants of both proteins were produced in which these residues were mutated to Ala, Glu, or Arg. The resulting mutants exhibited oligomerization patterns and ligand binding properties similar to those of their wild-type counterparts. In contrast, all three mutations strongly inhibited the interaction of L- and H-ficolins with MAp19 and MASP-2 and impaired the ability of each ficolin to trigger the lectin pathway. In the case of MASP-1 and MASP-3, replacement of the target Lys residues by Ala or Glu abolished interaction, whereas the Lys to Arg mutations had only slight inhibitory effects. Likewise, binding of each ficolin to CRT was inhibited by mutation of Lys to Ala or Glu, but not to Arg. In conclusion, residues Lys(57) of L-ficolin and Lys(47) of H-ficolin are key components of the interaction with the MASPs and CRT, providing strong indication that MBL and the ficolins share homologous binding sites for both types of proteins.
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Affiliation(s)
- Monique Lacroix
- Institut de Biologie Structurale Jean-Pierre Ebel, Unité Mixte de Recherche 5075, Centre National de la Recherche Scientifique-Commissariat à l'Energie Atomique, Université Joseph Fourier, Grenoble, France
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34
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Graham SC, Assenberg R, Delmas O, Verma A, Gholami A, Talbi C, Owens RJ, Stuart DI, Grimes JM, Bourhy H. Rhabdovirus matrix protein structures reveal a novel mode of self-association. PLoS Pathog 2008; 4:e1000251. [PMID: 19112510 PMCID: PMC2603668 DOI: 10.1371/journal.ppat.1000251] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Accepted: 12/01/2008] [Indexed: 01/18/2023] Open
Abstract
The matrix (M) proteins of rhabdoviruses are multifunctional proteins essential for virus maturation and budding that also regulate the expression of viral and host proteins. We have solved the structures of M from the vesicular stomatitis virus serotype New Jersey (genus: Vesiculovirus) and from Lagos bat virus (genus: Lyssavirus), revealing that both share a common fold despite sharing no identifiable sequence homology. Strikingly, in both structures a stretch of residues from the otherwise-disordered N terminus of a crystallographically adjacent molecule is observed binding to a hydrophobic cavity on the surface of the protein, thereby forming non-covalent linear polymers of M in the crystals. While the overall topology of the interaction is conserved between the two structures, the molecular details of the interactions are completely different. The observed interactions provide a compelling model for the flexible self-assembly of the matrix protein during virion morphogenesis and may also modulate interactions with host proteins.
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Affiliation(s)
- Stephen C Graham
- Division of Structural Biology and Oxford Protein Production Facility, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
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35
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Abstract
Measles virus belongs to the Paramyxoviridae family within the Mononegavirales order. Its nonsegmented, single-stranded, negative-sense RNA genome is encapsidated by the nucleoprotein (N) to form a helical nucleocapsid. This ribonucleoproteic complex is the substrate for both transcription and replication. The RNA-dependent RNA polymerase binds to the nucleocapsid template via its co-factor, the phosphoprotein (P). This chapter describes the main structural information available on the nucleoprotein, showing that it consists of a structured core (N(CORE)) and an intrinsically disordered C-terminal domain (N(TAIL)). We propose a model where the dynamic breaking and reforming of the interaction between N(TAIL) and P would allow the polymerase complex (L-P) to cartwheel on the nucleocapsid template. We also propose a model where the flexibility of the disordered N and P domains allows the formation of a tripartite complex (No-P-L) during replication, followed by the delivery of N monomers to the newly synthesized genomic RNA chain. Finally, the functional implications of structural disorder are also discussed in light of the ability of disordered regions to establish interactions with multiple partners, thus leading to multiple biological effects.
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Affiliation(s)
- S Longhi
- Architecture et Fonction des Macromolécules Biologiques, UMR 6098 CNRS et Universités Aix-Marseille I et II, 163 avenue de Luminy, Case 932, 13288 Marseille Cedex 09, France.
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36
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Chen M, Ogino T, Banerjee AK. Interaction of vesicular stomatitis virus P and N proteins: identification of two overlapping domains at the N terminus of P that are involved in N0-P complex formation and encapsidation of viral genome RNA. J Virol 2007; 81:13478-85. [PMID: 17913815 PMCID: PMC2168881 DOI: 10.1128/jvi.01244-07] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The nucleocapsid (N) protein of nonsegmented negative-strand (NNS) RNA viruses, when expressed in eukaryotic cells, aggregates and forms nucleocapsid-like complexes with cellular RNAs. The phosphoprotein (P) has been shown to prevent such aggregation by forming a soluble complex with the N protein free from cellular RNAs (designated N(0)). The N(0)-P complex presumably mediates specific encapsidation of the viral genome RNA. The precise mechanism by which the P protein carries out this function remains unclear. Here, by using a series of deleted and truncated mutant forms of the P protein of vesicular stomatitis virus (VSV), Indiana serotype, we present evidence that the N-terminal 11 to 30 amino acids (aa) of the P protein are essential in keeping the N protein soluble. Furthermore, glutathione S-transferase fused to the N-terminal 40 aa by itself is able to form the N(0)-P complex. Interestingly, the N-terminal 40-aa stretch failed to interact with the viral genome N-RNA template whereas the C-terminal 72 aa of the P protein interacted specifically with the latter. With an in vivo VSV minigenome transcription system, we further show that a deletion mutant form of P (PDelta1-10) lacking the N-terminal 10 aa which is capable of forming the N(0)-P complex was unable to support VSV minigenome transcription, although it efficiently supported transcription in vitro in a transcription-reconstitution reaction when used as purified protein. However, the same mutant protein complemented minigenome transcription when expressed together with a transcription-defective P deletion mutant protein containing N-terminal aa 1 to 210 (PDeltaII+III). Since the minigenome RNA needs to be encapsidated before transcription ensues, it seems that the entire N-terminal 210 aa are required for efficient genome RNA encapsidation. Taking these results together, we conclude that the N-terminal 11 to 30 aa are required for N(0)-P complex formation but the N-terminal 210 aa are required for genome RNA encapsidation.
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Affiliation(s)
- Mingzhou Chen
- Department of Molecular Genetics, Section of Virology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA
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37
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Wu X, Franka R, Velasco-Villa A, Rupprecht CE. Are all lyssavirus genes equal for phylogenetic analyses? Virus Res 2007; 129:91-103. [PMID: 17681631 DOI: 10.1016/j.virusres.2007.06.022] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2007] [Revised: 06/25/2007] [Accepted: 06/26/2007] [Indexed: 11/25/2022]
Abstract
Individual lyssavirus genes were evaluated for phylogenetic studies from available full genome sequences. The full genome of the ERA rabies virus was sequenced and its accuracy was confirmed through virus recovery by reverse genetics. The full length of the ERA is 11,931 nucleotides (nt), with a leader sequence of 58 nt, the nucleoprotein (N) gene of 1350 nt, phosphoprotein (P) gene of 891 nt, matrix protein (M) gene of 606 nt, glycoprotein (G) gene of 1572 nt, RNA-dependent RNA polymerase (L) gene of 6384 nt, Psi-region (or G-L intergenic region) of 400 nt, and a trailer region of 70 nt. The five mono-cistrons are separated by intergenic regions of 2, 5, 5 and 24 nt, respectively. One obvious difference between the ERA and SAD-B19 rabies virus strains was the putative stop/polyadenylation signal of the G gene, with a poly(A(8)) tract for ERA, and a poly(A(5)) for SAD-B19. The TGpoly(A(8)) sequence tract was identified to be a leaky termination signal in the ERA strain. Through analyses of nt diversity, protein co-variations, structural and functional constraints, and reconstruction of phylogenetic trees from comprehensive datasets, we propose lyssavirus genes probably are of similar value for phylogenetic analyses.
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Affiliation(s)
- Xianfu Wu
- Rabies Program/PRB, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA 30333, USA.
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38
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Kucinskaite I, Juozapaitis M, Serva A, Zvirbliene A, Johnson N, Staniulis J, Fooks AR, Müller T, Sasnauskas K, Ulrich RG. Antigenic characterisation of yeast-expressed lyssavirus nucleoproteins. Virus Genes 2007; 35:521-9. [PMID: 17619134 DOI: 10.1007/s11262-007-0127-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Accepted: 05/28/2007] [Indexed: 12/25/2022]
Abstract
In Europe, three genotypes of the genus Lyssavirus, family Rhabdoviridae, are present, classical rabies virus (RABV, genotype 1), European bat lyssavirus type 1 (EBLV-1, genotype 5) and European bat lyssavirus type 2 (EBLV-2, genotype 6). The entire authentic nucleoprotein (N protein) encoding sequences of RABV (challenge virus standard, CVS, strain), EBLV-1 and EBLV-2 were expressed in yeast Saccharomyces cerevisiae at high level. Purification of recombinant N proteins by caesium chloride gradient centrifugation resulted in yields between 14-17, 25-29 and 18-20 mg/l of induced yeast culture for RABV-CVS, EBLV-1 and EBLV-2, respectively. The purified N proteins were evaluated by negative staining electron microscopy, which revealed the formation of nucleocapsid-like structures. The antigenic conformation of the N proteins was investigated for their reactivity with monoclonal antibodies (mAbs) directed against different lyssaviruses. The reactivity pattern of each mAb was virtually identical between immunofluorescence assay with virus-infected cells, and ELISA and dot blot assay using the corresponding recombinant N proteins. These observations lead us to conclude that yeast-expressed lyssavirus N proteins share antigenic properties with naturally expressed virus protein. These recombinant proteins have the potential for use as components of serological assays for lyssaviruses.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antibodies, Monoclonal/isolation & purification
- Antibodies, Monoclonal/metabolism
- Antibodies, Viral/isolation & purification
- Antibodies, Viral/metabolism
- Antigens, Viral/biosynthesis
- Antigens, Viral/immunology
- Antigens, Viral/isolation & purification
- Cloning, Molecular
- Enzyme-Linked Immunosorbent Assay
- Fluorescent Antibody Technique, Direct
- Gene Expression
- Immunoblotting
- Lyssavirus/genetics
- Lyssavirus/immunology
- Mice
- Microscopy, Electron, Transmission
- Molecular Sequence Data
- Nucleoproteins/biosynthesis
- Nucleoproteins/immunology
- Nucleoproteins/isolation & purification
- Protein Binding
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
- Sequence Alignment
- Viral Proteins/biosynthesis
- Viral Proteins/immunology
- Viral Proteins/isolation & purification
- Virosomes/ultrastructure
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Affiliation(s)
- Indre Kucinskaite
- Institute of Biotechnology, V. Graiciūno 8, 02241, Vilnius, Lithuania
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39
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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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40
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Chelbi-Alix MK, Vidy A, El Bougrini J, Blondel D. Rabies viral mechanisms to escape the IFN system: the viral protein P interferes with IRF-3, Stat1, and PML nuclear bodies. J Interferon Cytokine Res 2007; 26:271-80. [PMID: 16689655 DOI: 10.1089/jir.2006.26.271] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Interferons (IFNs) are a family of secreted proteins with antiviral, antiproliferative, and immunomodulatory activities. The different biologic actions of IFN are believed to be mediated by the products of specifically IFN-stimulated genes (ISG) in the target cells. The IFN response is the first line of defense against viral infections. Viruses, which require the cellular machinery for their replication, have evolved different ways to counteract the action of IFN by inhibiting IFN production or Jak-Stat signaling or by altering ISG products. This review focuses on the role of viral proteins from the RNA virus family, particularly rabies P protein. P protein mediates inhibition of the IFN system by different pathways: it inhibits IFN production by impairing IFN regulatory factor-3 (IRF-3) phosphorylation and IFN signaling by blocking nuclear transport of Stat1 and alters promyelocytic leukemia (PML) nuclear bodies by retaining PML in the cytoplasm.
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41
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Shimizu K, Ito N, Mita T, Yamada K, Hosokawa-Muto J, Sugiyama M, Minamoto N. Involvement of nucleoprotein, phosphoprotein, and matrix protein genes of rabies virus in virulence for adult mice. Virus Res 2007; 123:154-60. [PMID: 17010466 DOI: 10.1016/j.virusres.2006.08.011] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2006] [Revised: 08/30/2006] [Accepted: 08/31/2006] [Indexed: 10/24/2022]
Abstract
Rabies virus Ni-CE strain causes nonlethal infection in adult mice after intracerebral inoculation, whereas the parental Nishigahara strain kills mice. In this study, to identify viral gene(s) related to the difference in pathogenicity between Ni-CE and Nishigahara strains, we generated chimeric viruses with respective genes of the virulent Nishigahara strain in the background of the avirulent Ni-CE genome. Since chimeric viruses, which had the N, P, or M genes of the Nishigahara strain, respectively, killed adult mice after intracerebral inoculation, it became evident that the N, P, and M genes are related to the difference in pathogenicity between Ni-CE and Nishigahara strains. Previously, we showed that the G gene is a major contributor to the difference in pathogenicity between another avirulent strain, RC-HL, and the parental Nishigahara strain. These results imply that the attenuation mechanism of the Ni-CE strain is different from that of the RC-HL strain, thus suggesting that rabies virus can be attenuated by diverse mechanisms. This is the first report of changes in viral genes other than the G gene of rabies virus causing the reversion of pathogenicity of an avirulent strain.
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Affiliation(s)
- Kenta Shimizu
- The United Graduate School of Veterinary Sciences, Gifu University, Japan
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42
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Albertini AAV, Clapier CR, Wernimont AK, Schoehn G, Weissenhorn W, Ruigrok RWH. Isolation and crystallization of a unique size category of recombinant Rabies virus Nucleoprotein-RNA rings. J Struct Biol 2006; 158:129-33. [PMID: 17126031 DOI: 10.1016/j.jsb.2006.10.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2006] [Revised: 10/10/2006] [Accepted: 10/15/2006] [Indexed: 11/21/2022]
Abstract
In order to study the packaging of rabies virus RNA inside the viral nucleocapsid, rabies nucleoprotein was expressed in insect cells. In the cells, it binds to cellular RNA to form long, helical or short circular complexes, depending on the length of the bound RNA. The circular complexes contained from 9 up to 13 N-protomers per ring. Separation of the rings into defined size classes was impossible through regular column chromatographies or gradient centrifugation. The size classes could be separated by native polyacrylamide gel electrophoresis. A large-scale separation was achieved with a 4% native gel using a preparative electrophoresis apparatus. Crystallization trials were set up with N-RNA rings from three size classes and crystals were obtained in all cases. The best diffracting crystals, diffracting up to 6A, contained rings with 11 N-protomers plus an RNA molecule of 99 nucleotides. The diffraction limit was improved to 3.5A by air dehydration prior to flash freezing.
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Affiliation(s)
- Aurélie A V Albertini
- Institut de Virologie Moléculaire et Structurale, FRE 2854 Université Joseph Fourier-CNRS, IVMS, c/o EMBL, BP 181, 38042 Grenoble cedex 9, France
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43
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Abstract
Contrary to their host cells, many viruses contain RNA as genetic material and hence encode an RNA-dependent RNA polymerase to replicate their genomes. This review discusses the present status of our knowledge on the structure of these enzymes and the mechanisms of RNA replication. The simplest viruses encode only the catalytic subunit of the replication complex, but other viruses also contribute a variable number of ancillary factors. These and other factors provided by the host cell play roles in the specificity and affinity of template recognition and the assembly of the replication complex. Usually, these host factors are involved in protein synthesis or RNA modification in the host cell, but they play roles in remodeling RNA-RNA, RNA-protein, and protein-protein interactions during virus RNA replication. Furthermore, viruses take advantage of and modify previous cell structural elements, frequently membrane vesicles, for the formation of RNA replication complexes.
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Affiliation(s)
- Juan Ortín
- Centro Nacional de Biotecnología (CSIC), 28049 Madrid, Spain.
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44
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Hu YC, Luo YL, Ji WT, Chulu JLC, Chang PC, Shieh H, Wang CY, Liu HJ. Dual expression of the HA protein of H5N2 avian influenza virus in a baculovirus system. J Virol Methods 2006; 135:43-8. [PMID: 16530857 DOI: 10.1016/j.jviromet.2006.01.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2005] [Revised: 01/19/2006] [Accepted: 01/23/2006] [Indexed: 11/19/2022]
Abstract
Baculovirus/insect cell system is used widely for recombinant protein production. The hemagglutinin (HA) gene of H5N2 avian influenza virus (AIV) 1209 strain and the enhanced green fluorescent protein (EGFP) gene were cloned into pFastBac DUAL vector that has two promoters and cloning sites, allowing simultaneous expression of these two genes. The HA protein of AIV was fused with a hexahistidine (His6) tag for purification. The coexpression of EGFP allowed identification of the recombinant baculoviruses in Sf-9 insect cells, eliminating cumbersome and time-consuming assays. A recombinant baculovirus, Bac-HA, was generated by transfecting pBac-HA to bacmid inside DH10B(AC)Escherichia coli by site-specific transposition, followed by transfection into the Sf-9 cells. Fluorescence in the insect cells was observed from 3 days post-infection. The expressed HA protein was confirmed by Western blot using an anti-HA monoclonal antibody. Also, different detergents and incubation times on ice were tested. The two-stage extraction with Triton X-100 or Tween 20 and incubation on ice for 2h exhibited high efficiency. Since purification of HA with ConA resin resulted in low protein recovery, lentil lectin affinity column was used and was useful for HA purification.
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Affiliation(s)
- Yu C Hu
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan
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45
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Green TJ, Zhang X, Wertz GW, Luo M. Structure of the vesicular stomatitis virus nucleoprotein-RNA complex. Science 2006; 313:357-60. [PMID: 16778022 DOI: 10.1126/science.1126953] [Citation(s) in RCA: 253] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Vesicular stomatitis virus is a negative-stranded RNA virus. Its nucleoprotein (N) binds the viral genomic RNA and is involved in multiple functions including transcription, replication, and assembly. We have determined a 2.9 angstrom structure of a complex containing 10 molecules of the N protein and 90 bases of RNA. The RNA is tightly sequestered in a cavity at the interface between two lobes of the N protein. This serves to protect the RNA in the absence of polynucleotide synthesis. For the RNA to be accessed, some conformational change in the N protein should be necessary.
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Affiliation(s)
- Todd J Green
- Department of Microbiology, School of Medicine, University of Alabama at Birmingham, 1025 18th Street South, Birmingham, AL 35294, USA
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Albertini AAV, Wernimont AK, Muziol T, Ravelli RBG, Clapier CR, Schoehn G, Weissenhorn W, Ruigrok RWH. Crystal structure of the rabies virus nucleoprotein-RNA complex. Science 2006; 313:360-3. [PMID: 16778023 DOI: 10.1126/science.1125280] [Citation(s) in RCA: 249] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Negative-strand RNA viruses condense their genome into a helical nucleoprotein-RNA complex, the nucleocapsid, which is packed into virions and serves as a template for the RNA-dependent RNA polymerase complex. The crystal structure of a recombinant rabies virus nucleoprotein-RNA complex, organized in an undecameric ring, has been determined at 3.5 angstrom resolution. Polymerization of the nucleoprotein is achieved by domain exchange between protomers, with flexible hinges allowing nucleocapsid formation. The two core domains of the nucleoprotein clamp around the RNA at their interface and shield it from the environment. RNA sequestering by nucleoproteins is likely a common mechanism used by negative-strand RNA viruses to protect their genomes from the innate immune response directed against viral RNA in human host cells at certain stages of an infectious cycle.
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Affiliation(s)
- Aurélie A V Albertini
- Institut de Virologie Moléculaire et Structurale, FRE 2854 Université Joseph Fourier-CNRS, Boite Postale 181, 38042 Grenoble, France
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Bourhis JM, Canard B, Longhi S. Structural disorder within the replicative complex of measles virus: functional implications. Virology 2006; 344:94-110. [PMID: 16364741 DOI: 10.1016/j.virol.2005.09.025] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2005] [Accepted: 09/10/2005] [Indexed: 11/29/2022]
Abstract
Measles virus belongs to the Paramyxoviridae family within the Mononegavirales order. Its non-segmented, single stranded, negative sense RNA genome is encapsidated by the nucleoprotein (N) to form a helical nucleocapsid. This ribonucleoproteic complex is the substrate for both transcription and replication. The RNA-dependent RNA polymerase binds to the nucleocapsid template via its co-factor, the phosphoprotein (P). In this review, we summarize the main experimental data pointing out the abundance of structural disorder within measles virus N and P. We also describe studies indicating that structural disorder is a widespread property in the replicative complex of Paramyxoviridae and, more generally, of Mononegavirales. The functional implications of structural disorder are also discussed. Finally, we propose a model where the flexibility of the disordered N and P domains allows the formation of a tripartite complex (N degrees-P-L) during replication, followed by the delivery of N monomers to the newly synthesized genomic RNA chain.
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Affiliation(s)
- Jean-Marie Bourhis
- Architecture et Fonction des Macromolécules Biologiques, UMR 6098 CNRS et Universités Aix-Marseille I et II, Campus de Luminy, 13288 Marseille Cedex 09, France
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Mavrakis M, Méhouas S, Réal E, Iseni F, Blondel D, Tordo N, Ruigrok RWH. Rabies virus chaperone: identification of the phosphoprotein peptide that keeps nucleoprotein soluble and free from non-specific RNA. Virology 2006; 349:422-9. [PMID: 16494915 DOI: 10.1016/j.virol.2006.01.030] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2005] [Revised: 01/12/2006] [Accepted: 01/24/2006] [Indexed: 11/25/2022]
Abstract
The genomic RNA of rabies virus is always complexed with the viral nucleoprotein (N). This N-RNA complex is the template for viral transcription and replication. The viral phosphoprotein (P) has two functions during the infection process: it binds through its carboxy-terminus to N in the N-RNA complex and at the same time with an amino-terminal domain to the polymerase and in this way fixes the polymerase to its template. The second function of P is to bind to newly produced N in the infected cell in order to prevent that N binds non-specifically and irreversibly to cellular RNA. In order to identify the part of the phosphoprotein that binds to N and keeps the latter soluble, we isolated the N-P complex, performed sequential protease digestions, and determined the identity of the remaining N and P peptides in the purified digested complex. Although the digestion steps removed short sequences of N, most of N remained intact and soluble, indicating that the overall structure was not affected. Most of P, including the carboxy-terminal N-RNA-binding domain, was removed during the first digestion step. N-terminal sequencing and mass spectrometry analysis identified a P peptide containing residues 4-40 that remained associated with N. Coexpression and coimmunoprecipitation experiments and yeast two-hybrid experiments showed that this peptide alone could bind to N in vivo.
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Affiliation(s)
- Manos Mavrakis
- EMBL Grenoble Outstation, B.P. 181, 38042 Grenoble cedex 9, France
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Toriumi H, Kawai A. Structural difference recognized by a monoclonal antibody #404-11 between the rabies virus nucleocapsid (NC) produced in virus infected cells and the NC-like structures produced in the nucleoprotein (N) cDNA-transfected cells. Microbiol Immunol 2005; 49:757-70. [PMID: 16113504 DOI: 10.1111/j.1348-0421.2005.tb03666.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We investigated structural changes in the rabies virus (HEP-Flury strain) nucleocapsid (NC) during the virus replication, for which we used two anti-nucleoprotein (N) monoclonal antibodies (mAbs), #404-11 (specific for a conformation-dependently exposed linear epitope) and #1-7-11 (specific for a conformational epitope which is exposed after the nucleocapsid formation). Both mAbs recognized the N protein of the viral NC, but not of the RNA-free N-P complex. The 1-7-11 and 404-11 epitopes could be mapped to the N-terminal and the C-terminal regions of N protein, respectively. Immunoprecipitation studies demonstrated that treatment of the NC either with the alkaline phosphatase or sodium deoxycholate (DOC) resulted in dissociation of most P proteins from the NC and in the reduced reactivity to mAb #404-11, but not to mAb #1-7-11. NC-like structures produced in the N cDNA-transfected cells displayed strong reactivity to mAb #1-7-11; however, reactivity to mAb #404-11 was very weak. And, coexpression with viral phosphoprotein (P) resulted in little increase in reactivity to mAb #404-11 of the NC-like structures, while the reactivity was significantly increased by cotransfection with P and the viral minigenome whose 3'- and 5'-end structures were derived from the viral genome. From these results, we assume that, although the 404-11 epitope is a linear one, the epitope-containing region is exposed only when N proteins encapsidate properly the viral RNA in collaboration with the P protein. Further, exposure of the 404-11 epitope region might be function-related, and be regulated by association and dissociation of the P protein.
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Affiliation(s)
- Harufusa Toriumi
- Department of Molecular Microbiology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
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Eshaghi M, Tan WS, Ong ST, Yusoff K. Purification and characterization of Nipah virus nucleocapsid protein produced in insect cells. J Clin Microbiol 2005; 43:3172-7. [PMID: 16000431 PMCID: PMC1169143 DOI: 10.1128/jcm.43.7.3172-3177.2005] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The nucleocapsid (N) protein of Nipah virus (NiV) is a major constituent of the viral proteins which play a role in encapsidation, regulating the transcription and replication of the viral genome. To investigate the use of a fusion system to aid the purification of the recombinant N protein for structural studies and potential use as a diagnostic reagent, the NiV N gene was cloned into the pFastBacHT vector and the His-tagged fusion protein was expressed in Sf9 insect cells by recombinant baculovirus. Western blot analysis of the recombinant fusion protein with anti-NiV antibodies produced a band of approximately 62 kDa. A time course study showed that the highest level of expression was achieved after 3 days of incubation. Electron microscopic analysis of the NiV recombinant N fusion protein purified on a nickel-nitrilotriacetic acid resin column revealed different types of structures, including spherical, ring-like, and herringbone-like particles. The light-scattering measurements of the recombinant N protein also confirmed the polydispersity of the sample with hyrdrodynamic radii of small and large types. The optical density spectra of the purified recombinant fusion protein revealed a high A(260)/A(280) ratio, indicating the presence of nucleic acids. Western blotting and enzyme-linked immunosorbent assay results showed that the recombinant N protein exhibited the antigenic sites and conformation necessary for specific antigen-antibody recognition.
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Affiliation(s)
- Majid Eshaghi
- Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, UPM 43400, Serdang, Selangor, Malaysia
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