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Gao Y, Raghavan A, Espinosa Garcia SA, Deng B, Hurtado de Mendoza D, Liang B. In vitro higher-order oligomeric assembly of the respiratory syncytial virus M2-1 protein with longer RNAs. J Virol 2024; 98:e0104624. [PMID: 39016557 PMCID: PMC11334520 DOI: 10.1128/jvi.01046-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2024] [Accepted: 06/24/2024] [Indexed: 07/18/2024] Open
Abstract
The respiratory syncytial virus (RSV) M2-1 protein is a transcriptional antitermination factor crucial for efficiently synthesizing multiple full-length viral mRNAs. During RSV infection, M2-1 exists in a complex with mRNA within cytoplasmic compartments called inclusion body-associated granules (IBAGs). Prior studies showed that M2-1 can bind along the entire length of viral mRNAs instead of just gene-end (GE) sequences, suggesting that M2-1 has more sophisticated RNA recognition and binding characteristics. Here, we analyzed the higher oligomeric complexes formed by M2-1 and RNAs in vitro using size exclusion chromatography (SEC), electrophoretic mobility shift assays (EMSA), negative stain electron microscopy (EM), and mutagenesis. We observed that the minimal RNA length for such higher oligomeric assembly is about 14 nucleotides for polyadenine sequences, and longer RNAs exhibit distinct RNA-induced binding modality to M2-1, leading to enhanced particle formation frequency and particle homogeneity as the local RNA concentration increases. We showed that particular cysteine residues of the M2-1 cysteine-cysteine-cystine-histidine (CCCH) zinc-binding motif are essential for higher oligomeric assembly. Furthermore, complexes assembled with long polyadenine sequences remain unaffected when co-incubated with ribonucleases or a zinc chelation agent. Our study provided new insights into the higher oligomeric assembly of M2-1 with longer RNA.IMPORTANCERespiratory syncytial virus (RSV) causes significant respiratory infections in infants, the elderly, and immunocompromised individuals. The virus forms specialized compartments to produce genetic material, with the M2-1 protein playing a pivotal role. M2-1 acts as an anti-terminator in viral transcription, ensuring the creation of complete viral mRNA and associating with both viral and cellular mRNA. Our research focuses on understanding M2-1's function in viral mRNA synthesis by modeling interactions in a controlled environment. This approach is crucial due to the challenges of studying these compartments in vivo. Reconstructing the system in vitro uncovers structural and biochemical aspects and reveals the potential functions of M2-1 and its homologs in related viruses. Our work may contribute to identifying targets for antiviral inhibitors and advancing RSV infection treatment.
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Affiliation(s)
- Yunrong Gao
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Anirudh Raghavan
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA
| | | | - Bowei Deng
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA
| | | | - Bo Liang
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA
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2
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Whitehead JD, Decool H, Leyrat C, Carrique L, Fix J, Eléouët JF, Galloux M, Renner M. Structure of the N-RNA/P interface indicates mode of L/P recruitment to the nucleocapsid of human metapneumovirus. Nat Commun 2023; 14:7627. [PMID: 37993464 PMCID: PMC10665349 DOI: 10.1038/s41467-023-43434-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 11/08/2023] [Indexed: 11/24/2023] Open
Abstract
Human metapneumovirus (HMPV) is a major cause of respiratory illness in young children. The HMPV polymerase (L) binds an obligate cofactor, the phosphoprotein (P). During replication and transcription, the L/P complex traverses the viral RNA genome, which is encapsidated within nucleoproteins (N). An essential interaction between N and a C-terminal region of P tethers the L/P polymerase to the template. This N-P interaction is also involved in the formation of cytoplasmic viral factories in infected cells, called inclusion bodies. To define how the polymerase component P recognizes N-encapsidated RNA (N-RNA) we employed cryogenic electron microscopy (cryo-EM) and molecular dynamics simulations, coupled to activity assays and imaging of inclusion bodies in cells. We report a 2.9 Å resolution structure of a triple-complex between multimeric N, bound to both RNA and the C-terminal region of P. Furthermore, we also present cryo-EM structures of assembled N in different oligomeric states, highlighting the plasticity of N. Combined with our functional assays, these structural data delineate in molecular detail how P attaches to N-RNA whilst retaining substantial conformational dynamics. Moreover, the N-RNA-P triple complex structure provides a molecular blueprint for the design of therapeutics to potentially disrupt the attachment of L/P to its template.
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Affiliation(s)
- Jack D Whitehead
- Division of Structural Biology, The Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Hortense Decool
- Université Paris-Saclay, INRAE, UVSQ, VIM, 78350, Jouy-en-Josas, France
| | - Cédric Leyrat
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Loic Carrique
- Division of Structural Biology, The Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Jenna Fix
- Université Paris-Saclay, INRAE, UVSQ, VIM, 78350, Jouy-en-Josas, France
| | | | - Marie Galloux
- Université Paris-Saclay, INRAE, UVSQ, VIM, 78350, Jouy-en-Josas, France.
| | - Max Renner
- Department of Chemistry, Umeå University, Umeå, Sweden.
- Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden.
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Diot C, Richard CA, Risso-Ballester J, Martin D, Fix J, Eléouët JF, Sizun C, Rameix-Welti MA, Galloux M. Hardening of Respiratory Syncytial Virus Inclusion Bodies by Cyclopamine Proceeds through Perturbation of the Interactions of the M2-1 Protein with RNA and the P Protein. Int J Mol Sci 2023; 24:13862. [PMID: 37762166 PMCID: PMC10531356 DOI: 10.3390/ijms241813862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Revised: 08/20/2023] [Accepted: 09/04/2023] [Indexed: 09/29/2023] Open
Abstract
Respiratory syncytial virus (RSV) RNA synthesis takes place in cytoplasmic viral factories also called inclusion bodies (IBs), which are membrane-less organelles concentrating the viral RNA polymerase complex. The assembly of IBs is driven by liquid-liquid phase separation promoted by interactions between the viral nucleoprotein N and the phosphoprotein P. We recently demonstrated that cyclopamine (CPM) inhibits RSV multiplication by disorganizing and hardening IBs. Although a single mutation in the viral transcription factor M2-1 induced resistance to CPM, the mechanism of action of CPM still remains to be characterized. Here, using FRAP experiments on reconstituted pseudo-IBs both in cellula and in vitro, we first demonstrated that CPM activity depends on the presence of M2-1 together with N and P. We showed that CPM impairs the competition between P and RNA binding to M2-1. As mutations on both P and M2-1 induced resistance against CPM activity, we suggest that CPM may affect the dynamics of the M2-1-P interaction, thereby affecting the relative mobility of the proteins contained in RSV IBs. Overall, our results reveal that stabilizing viral protein-protein interactions is an attractive new antiviral approach. They pave the way for the rational chemical optimization of new specific anti-RSV molecules.
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Affiliation(s)
- Cédric Diot
- Institut Pasteur, Université Paris Cité, M3P, F-75015 Paris, France;
- INSERM, UMR 1173 (2I), Université Paris-Saclay-Versailles St. Quentin, M3P, F-78180 Versailles, France;
| | - Charles-Adrien Richard
- INRAE, Unité de Virologie et Immunologie Moléculaires (VIM), Université Paris-Saclay-Versailles St. Quentin, F-78350 Jouy-en-Josas, France; (C.-A.R.); (D.M.); (J.F.); (J.-F.E.)
| | - Jennifer Risso-Ballester
- INSERM, UMR 1173 (2I), Université Paris-Saclay-Versailles St. Quentin, M3P, F-78180 Versailles, France;
| | - Davy Martin
- INRAE, Unité de Virologie et Immunologie Moléculaires (VIM), Université Paris-Saclay-Versailles St. Quentin, F-78350 Jouy-en-Josas, France; (C.-A.R.); (D.M.); (J.F.); (J.-F.E.)
| | - Jenna Fix
- INRAE, Unité de Virologie et Immunologie Moléculaires (VIM), Université Paris-Saclay-Versailles St. Quentin, F-78350 Jouy-en-Josas, France; (C.-A.R.); (D.M.); (J.F.); (J.-F.E.)
| | - Jean-François Eléouët
- INRAE, Unité de Virologie et Immunologie Moléculaires (VIM), Université Paris-Saclay-Versailles St. Quentin, F-78350 Jouy-en-Josas, France; (C.-A.R.); (D.M.); (J.F.); (J.-F.E.)
| | - Christina Sizun
- Institut de Chimie des Substances Naturelles, CNRS, Université Paris-Saclay, F-91190 Gif-sur-Yvette, France;
| | - Marie-Anne Rameix-Welti
- INSERM, UMR 1173 (2I), Université Paris-Saclay-Versailles St. Quentin, M3P, F-78180 Versailles, France;
- Laboratoire de Microbiologie, Hôpital Ambroise Paré, Assistance Publique des Hôpitaux de Paris, DMU15, F-75015 Paris, France
| | - Marie Galloux
- INRAE, Unité de Virologie et Immunologie Moléculaires (VIM), Université Paris-Saclay-Versailles St. Quentin, F-78350 Jouy-en-Josas, France; (C.-A.R.); (D.M.); (J.F.); (J.-F.E.)
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4
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Boggs KB, Edmonds K, Cifuentes-Munoz N, El Najjar F, Ossandón C, Roe M, Wu C, Moncman CL, Creamer TP, Amarasinghe GK, Leung DW, Dutch RE. Human Metapneumovirus Phosphoprotein Independently Drives Phase Separation and Recruits Nucleoprotein to Liquid-Like Bodies. mBio 2022; 13:e0109922. [PMID: 35536005 PMCID: PMC9239117 DOI: 10.1128/mbio.01099-22] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 04/20/2022] [Indexed: 11/20/2022] Open
Abstract
Human metapneumovirus (HMPV) inclusion bodies (IBs) are dynamic structures required for efficient viral replication and transcription. The minimum components needed to form IB-like structures in cells are the nucleoprotein (N) and the tetrameric phosphoprotein (P). HMPV P binds to the following two versions of the N protein in infected cells: N-terminal P residues interact with monomeric N (N0) to maintain a pool of protein to encapsidate new RNA and C-terminal P residues interact with oligomeric, RNA-bound N (N-RNA). Recent work on other negative-strand viruses has suggested that IBs are, at least in part, liquid-like phase-separated membraneless organelles. Here, HMPV IBs in infected or transfected cells were shown to possess liquid organelle properties, such as fusion and fission. Recombinant versions of HMPV N and P proteins were purified to analyze the interactions required to drive phase separation in vitro. Purified HMPV P was shown to form liquid droplets in isolation. This observation is distinct from other viral systems that also form IBs. Partial removal of nucleic acid from purified P altered phase-separation dynamics, suggesting that nucleic acid interactions play a role in IB formation. HMPV P also recruits monomeric N (N0-P) and N-RNA to droplets in vitro. These findings suggest that HMPV P may also act as a scaffold protein to mediate multivalent interactions with monomeric and oligomeric N, as well as RNA, to promote phase separation of IBs. Together, these findings highlight an additional layer of regulation in HMPV replication by the viral P and N proteins. IMPORTANCE Human metapneumovirus (HMPV) is a leading cause of respiratory disease among children, immunocompromised individuals, and the elderly. Currently, no vaccines or antivirals are available for the treatment of HMPV infections. Cytoplasmic inclusion bodies (IBs), where HMPV replication and transcription occur, represent a promising target for the development of novel antivirals. The HMPV nucleoprotein (N) and phosphoprotein (P) are the minimal components needed for IB formation in eukaryotic cells. However, interactions that regulate the formation of these dynamic structures are poorly understood. Here, we showed that HMPV IBs possess the properties of liquid organelles and that purified HMPV P phase separates independently in vitro. Our work suggests that HMPV P phase-separation dynamics are altered by nucleic acid. We provide strong evidence that, unlike results reported from other viral systems, HMPV P alone can serve as a scaffold for multivalent interactions with monomeric (N0) and oligomeric (N-RNA) HMPV N for IB formation.
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Affiliation(s)
- Kerri Beth Boggs
- Department of Molecular and Cellular Biochemistry, University of Kentucky, College of Medicine, Lexington, Kentucky, USA
| | - Kearstin Edmonds
- Department of Molecular and Cellular Biochemistry, University of Kentucky, College of Medicine, Lexington, Kentucky, USA
| | - Nicolas Cifuentes-Munoz
- Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago, Chile
| | - Farah El Najjar
- Department of Molecular and Cellular Biochemistry, University of Kentucky, College of Medicine, Lexington, Kentucky, USA
| | - Conny Ossandón
- Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de Antofagasta, Antofagasta, Chile
| | - McKenna Roe
- Department of Molecular and Cellular Biochemistry, University of Kentucky, College of Medicine, Lexington, Kentucky, USA
| | - Chao Wu
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Carole L. Moncman
- Department of Molecular and Cellular Biochemistry, University of Kentucky, College of Medicine, Lexington, Kentucky, USA
| | - Trevor P. Creamer
- Department of Molecular and Cellular Biochemistry, University of Kentucky, College of Medicine, Lexington, Kentucky, USA
| | - Gaya K. Amarasinghe
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Daisy W. Leung
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Rebecca Ellis Dutch
- Department of Molecular and Cellular Biochemistry, University of Kentucky, College of Medicine, Lexington, Kentucky, USA
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5
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Conley MJ, Short JM, Burns AM, Streetley J, Hutchings J, Bakker SE, Power BJ, Jaffery H, Haney J, Zanetti G, Murcia PR, Stewart M, Fearns R, Vijayakrishnan S, Bhella D. Helical ordering of envelope-associated proteins and glycoproteins in respiratory syncytial virus. EMBO J 2022; 41:e109728. [PMID: 34935163 PMCID: PMC8804925 DOI: 10.15252/embj.2021109728] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 12/01/2021] [Accepted: 12/03/2021] [Indexed: 12/20/2022] Open
Abstract
Human respiratory syncytial virus (RSV) causes severe respiratory illness in children and the elderly. Here, using cryogenic electron microscopy and tomography combined with computational image analysis and three-dimensional reconstruction, we show that there is extensive helical ordering of the envelope-associated proteins and glycoproteins of RSV filamentous virions. We calculated a 16 Å resolution sub-tomogram average of the matrix protein (M) layer that forms an endoskeleton below the viral envelope. These data define a helical lattice of M-dimers, showing how M is oriented relative to the viral envelope. Glycoproteins that stud the viral envelope were also found to be helically ordered, a property that was coordinated by the M-layer. Furthermore, envelope glycoproteins clustered in pairs, a feature that may have implications for the conformation of fusion (F) glycoprotein epitopes that are the principal target for vaccine and monoclonal antibody development. We also report the presence, in authentic virus infections, of N-RNA rings packaged within RSV virions. These data provide molecular insight into the organisation of the virion and the mechanism of its assembly.
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Affiliation(s)
- Michaela J Conley
- Medical Research Council – University of Glasgow Centre for Virus ResearchGlasgowUK
| | - Judith M Short
- Medical Research Council Laboratory of Molecular BiologyCambridgeUK
| | - Andrew M Burns
- Medical Research Council – University of Glasgow Centre for Virus ResearchGlasgowUK
| | - James Streetley
- Medical Research Council – University of Glasgow Centre for Virus ResearchGlasgowUK
| | - Joshua Hutchings
- Department of Biological SciencesBirkbeck CollegeLondonUK
- Present address:
Division of Biological SciencesUniversity of California San DiegoLa JollaCAUSA
| | - Saskia E Bakker
- Medical Research Council – University of Glasgow Centre for Virus ResearchGlasgowUK
- Present address:
School of Life SciencesUniversity of WarwickCoventryUK
| | - B Joanne Power
- Medical Research Council – University of Glasgow Centre for Virus ResearchGlasgowUK
- Present address:
Department of Biochemistry and Molecular BiologyThe Huck Center for Malaria ResearchPennsylvania State UniversityUniversity ParkPAUSA
| | - Hussain Jaffery
- Medical Research Council – University of Glasgow Centre for Virus ResearchGlasgowUK
| | - Joanne Haney
- Medical Research Council – University of Glasgow Centre for Virus ResearchGlasgowUK
| | - Giulia Zanetti
- Department of Biological SciencesBirkbeck CollegeLondonUK
| | - Pablo R Murcia
- Medical Research Council – University of Glasgow Centre for Virus ResearchGlasgowUK
| | - Murray Stewart
- Medical Research Council Laboratory of Molecular BiologyCambridgeUK
| | - Rachel Fearns
- Department of MicrobiologyBoston University School of MedicineBostonMAUSA
- National Emerging Infectious Diseases LaboratoriesBoston UniversityBostonMAUSA
| | | | - David Bhella
- Medical Research Council – University of Glasgow Centre for Virus ResearchGlasgowUK
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6
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Structural Insights into the Respiratory Syncytial Virus RNA Synthesis Complexes. Viruses 2021; 13:v13050834. [PMID: 34063087 PMCID: PMC8147935 DOI: 10.3390/v13050834] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 04/30/2021] [Accepted: 05/02/2021] [Indexed: 12/13/2022] Open
Abstract
RNA synthesis in respiratory syncytial virus (RSV), a negative-sense (-) nonsegmented RNA virus, consists of viral gene transcription and genome replication. Gene transcription includes the positive-sense (+) viral mRNA synthesis, 5'-RNA capping and methylation, and 3' end polyadenylation. Genome replication includes (+) RNA antigenome and (-) RNA genome synthesis. RSV executes the viral RNA synthesis using an RNA synthesis ribonucleoprotein (RNP) complex, comprising four proteins, the nucleoprotein (N), the large protein (L), the phosphoprotein (P), and the M2-1 protein. We provide an overview of the RSV RNA synthesis and the structural insights into the RSV gene transcription and genome replication process. We propose a model of how the essential four proteins coordinate their activities in different RNA synthesis processes.
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7
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Braun MR, Noton SL, Blanchard EL, Shareef A, Santangelo PJ, Johnson WE, Fearns R. Respiratory syncytial virus M2-1 protein associates non-specifically with viral messenger RNA and with specific cellular messenger RNA transcripts. PLoS Pathog 2021; 17:e1009589. [PMID: 34003848 PMCID: PMC8162694 DOI: 10.1371/journal.ppat.1009589] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 05/28/2021] [Accepted: 04/26/2021] [Indexed: 11/18/2022] Open
Abstract
Respiratory syncytial virus (RSV) is a major cause of respiratory disease in infants and the elderly. RSV is a non-segmented negative strand RNA virus. The viral M2-1 protein plays a key role in viral transcription, serving as an elongation factor to enable synthesis of full-length mRNAs. M2-1 contains an unusual CCCH zinc-finger motif that is conserved in the related human metapneumovirus M2-1 protein and filovirus VP30 proteins. Previous biochemical studies have suggested that RSV M2-1 might bind to specific virus RNA sequences, such as the transcription gene end signals or poly A tails, but there was no clear consensus on what RSV sequences it binds. To determine if M2-1 binds to specific RSV RNA sequences during infection, we mapped points of M2-1:RNA interactions in RSV-infected cells at 8 and 18 hours post infection using crosslinking immunoprecipitation with RNA sequencing (CLIP-Seq). This analysis revealed that M2-1 interacts specifically with positive sense RSV RNA, but not negative sense genome RNA. It also showed that M2-1 makes contacts along the length of each viral mRNA, indicating that M2-1 functions as a component of the transcriptase complex, transiently associating with nascent mRNA being extruded from the polymerase. In addition, we found that M2-1 binds specific cellular mRNAs. In contrast to the situation with RSV mRNA, M2-1 binds discrete sites within cellular mRNAs, with a preference for A/U rich sequences. These results suggest that in addition to its previously described role in transcription elongation, M2-1 might have an additional role involving cellular RNA interactions.
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Affiliation(s)
- Molly R. Braun
- Department of Microbiology, Boston University School of Medicine; National Emerging Infectious Diseases Laboratories, Boston University, Boston, Massachusetts, United States of America
| | - Sarah L. Noton
- Department of Microbiology, Boston University School of Medicine; National Emerging Infectious Diseases Laboratories, Boston University, Boston, Massachusetts, United States of America
| | - Emmeline L. Blanchard
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States of America
| | - Afzaal Shareef
- Department of Microbiology, Boston University School of Medicine; National Emerging Infectious Diseases Laboratories, Boston University, Boston, Massachusetts, United States of America
| | - Philip J. Santangelo
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States of America
| | - W. Evan Johnson
- Division of Computational Biomedicine and Bioinformatics Program and Department of Biostatistics, Boston University, Boston, Massachusetts, United States of America
| | - Rachel Fearns
- Department of Microbiology, Boston University School of Medicine; National Emerging Infectious Diseases Laboratories, Boston University, Boston, Massachusetts, United States of America
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Cardone C, Caseau CM, Pereira N, Sizun C. Pneumoviral Phosphoprotein, a Multidomain Adaptor-Like Protein of Apparent Low Structural Complexity and High Conformational Versatility. Int J Mol Sci 2021; 22:ijms22041537. [PMID: 33546457 PMCID: PMC7913705 DOI: 10.3390/ijms22041537] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 01/31/2021] [Accepted: 02/01/2021] [Indexed: 01/16/2023] Open
Abstract
Mononegavirales phosphoproteins (P) are essential co-factors of the viral polymerase by serving as a linchpin between the catalytic subunit and the ribonucleoprotein template. They have highly diverged, but their overall architecture is conserved. They are multidomain proteins, which all possess an oligomerization domain that separates N- and C-terminal domains. Large intrinsically disordered regions constitute their hallmark. Here, we exemplify their structural features and interaction potential, based on the Pneumoviridae P proteins. These P proteins are rather small, and their oligomerization domain is the only part with a defined 3D structure, owing to a quaternary arrangement. All other parts are either flexible or form short-lived secondary structure elements that transiently associate with the rest of the protein. Pneumoviridae P proteins interact with several viral and cellular proteins that are essential for viral transcription and replication. The combination of intrinsic disorder and tetrameric organization enables them to structurally adapt to different partners and to act as adaptor-like platforms to bring the latter close in space. Transient structures are stabilized in complex with protein partners. This class of proteins gives an insight into the structural versatility of non-globular intrinsically disordered protein domains.
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Biophysical and Dynamic Characterization of Fine-Tuned Binding of the Human Respiratory Syncytial Virus M2-1 Core Domain to Long RNAs. J Virol 2020; 94:JVI.01505-20. [PMID: 32938771 DOI: 10.1128/jvi.01505-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 09/15/2020] [Indexed: 11/20/2022] Open
Abstract
The human respiratory syncytial virus (hRSV) M2-1 protein functions as a processivity and antitermination factor of the viral polymerase complex. Here, the first evidence that the hRSV M2-1 core domain (cdM2-1) alone has an unfolding activity for long RNAs is presented and the biophysical and dynamic characterization of the cdM2-1/RNA complex is provided. The main contact region of cdM2-1 with RNA was the α1-α2-α5-α6 helix bundle, which suffered local conformational changes and promoted the RNA unfolding activity. This activity may be triggered by base-pairing recognition. RNA molecules wrap around the whole cdM2-1, protruding their termini over the domain. The α2-α3 and α3-α4 loops of cdM2-1 were marked by an increase in picosecond internal motions upon RNA binding, even though they are not directly involved in the interaction. The results revealed that the cdM2-1/RNA complex originates from a fine-tuned binding, contributing to the unraveling interaction aspects necessary for M2-1 activity.IMPORTANCE The main outcome is the molecular description of the fine-tuned binding of the cdM2-1/RNA complex and the provision of evidence that the domain alone has unfolding activity for long RNAs. This binding mode is essential in the understanding of the function in the full-length protein. Human respiratory syncytial virus (hRSV), an orthopneumovirus, stands out for the unique role of its M2-1 protein as a transcriptional antitermination factor able to increase RNA polymerase processivity.
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Kleiner VA, Fearns R. RSV M2-1 Protein in Complex with RNA: Old Questions Are Answered and a New One Emerges. Structure 2020; 28:977-978. [PMID: 32877647 DOI: 10.1016/j.str.2020.08.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The respiratory syncytial virus (RSV) M2-1 protein is essential for virus transcription. In this issue of Structure, Gao et al. (2020) describe the crystal structure of M2-1 in complex with RNA. This structure provides new insight into the RSV transcription mechanism but also raises an intriguing question regarding M2-1's function.
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Affiliation(s)
- Victoria Anne Kleiner
- Department of Microbiology, Boston University School of Medicine, Boston, MA 02118, USA
| | - Rachel Fearns
- Department of Microbiology, Boston University School of Medicine, Boston, MA 02118, USA.
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Abstract
Mononegavirales, known as nonsegmented negative-sense (NNS) RNA viruses, are a class of pathogenic and sometimes deadly viruses that include rabies virus (RABV), human respiratory syncytial virus (HRSV), and Ebola virus (EBOV). Unfortunately, no effective vaccines and antiviral therapeutics against many Mononegavirales are currently available. Viral polymerases have been attractive and major antiviral therapeutic targets. Therefore, Mononegavirales polymerases have been extensively investigated for their structures and functions. Mononegavirales, known as nonsegmented negative-sense (NNS) RNA viruses, are a class of pathogenic and sometimes deadly viruses that include rabies virus (RABV), human respiratory syncytial virus (HRSV), and Ebola virus (EBOV). Unfortunately, no effective vaccines and antiviral therapeutics against many Mononegavirales are currently available. Viral polymerases have been attractive and major antiviral therapeutic targets. Therefore, Mononegavirales polymerases have been extensively investigated for their structures and functions. Mononegavirales mimic RNA synthesis of their eukaryotic counterparts by utilizing multifunctional RNA polymerases to replicate entire viral genomes and transcribe viral mRNAs from individual viral genes as well as synthesize 5′ methylated cap and 3′ poly(A) tail of the transcribed viral mRNAs. The catalytic subunit large protein (L) and cofactor phosphoprotein (P) constitute the Mononegavirales polymerases. In this review, we discuss the shared and unique features of RNA synthesis, the monomeric multifunctional enzyme L, and the oligomeric multimodular adapter P of Mononegavirales. We outline the structural analyses of the Mononegavirales polymerases since the first structure of the vesicular stomatitis virus (VSV) L protein determined in 2015 and highlight multiple high-resolution cryo-electron microscopy (cryo-EM) structures of the polymerases of Mononegavirales, namely, VSV, RABV, HRSV, human metapneumovirus (HMPV), and human parainfluenza virus (HPIV), that have been reported in recent months (2019 to 2020). We compare the structures of those polymerases grouped by virus family, illustrate the similarities and differences among those polymerases, and reveal the potential RNA synthesis mechanisms and models of highly conserved Mononegavirales. We conclude by the discussion of remaining questions, evolutionary perspectives, and future directions.
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12
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Gao Y, Cao D, Pawnikar S, John KP, Ahn HM, Hill S, Ha JM, Parikh P, Ogilvie C, Swain A, Yang A, Bell A, Salazar A, Miao Y, Liang B. Structure of the Human Respiratory Syncytial Virus M2-1 Protein in Complex with a Short Positive-Sense Gene-End RNA. Structure 2020; 28:979-990.e4. [PMID: 32697936 DOI: 10.1016/j.str.2020.07.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 06/19/2020] [Accepted: 07/01/2020] [Indexed: 12/25/2022]
Abstract
The M2-1 protein of human respiratory syncytial virus (HRSV) is a transcription anti-terminator that regulates the processivity of the HRSV RNA-dependent RNA polymerase (RdRP). Here, we report a crystal structure of HRSV M2-1 bound to a short positive-sense gene-end RNA (SH7) at 2.7 Å resolution. We identified multiple critical residues of M2-1 involved in RNA interaction and examined their roles using mutagenesis and MicroScale Thermophoresis (MST) assay. We found that hydrophobic residue Phe23 is indispensable for M2-1 to recognize the base of RNA. We also captured spontaneous binding of RNA (SH7) to M2-1 in all-atom simulations using a robust Gaussian accelerated molecular dynamics (GaMD) method. Both experiments and simulations revealed that the interactions of RNA with two separate domains of M2-1, the zinc-binding domain (ZBD) and the core domain (CD), are independent of each other. Collectively, our results provided a structural basis for RNA recognition by HRSV M2-1.
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Affiliation(s)
- Yunrong Gao
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322 USA
| | - Dongdong Cao
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322 USA
| | - Shristi Pawnikar
- Center for Computational Biology and Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66047, USA
| | - Karen P John
- Center for Computational Biology and Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66047, USA
| | - Hyunjun Max Ahn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322 USA
| | - Shaylan Hill
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322 USA
| | - Ju Mi Ha
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322 USA
| | - Priyal Parikh
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322 USA
| | - Claire Ogilvie
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322 USA
| | - Anshuman Swain
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322 USA
| | - Amy Yang
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322 USA
| | - Amber Bell
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322 USA
| | - Angela Salazar
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322 USA
| | - Yinglong Miao
- Center for Computational Biology and Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66047, USA.
| | - Bo Liang
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322 USA.
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Insights into Interactions of Flavanones with Target Human Respiratory Syncytial Virus M 2-1 Protein from STD-NMR, Fluorescence Spectroscopy, and Computational Simulations. Int J Mol Sci 2020; 21:ijms21062241. [PMID: 32213871 PMCID: PMC7139479 DOI: 10.3390/ijms21062241] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 03/17/2020] [Accepted: 03/19/2020] [Indexed: 02/06/2023] Open
Abstract
The human Respiratory Syncytial Virus (hRSV) is the most frequent agent of respiratory infections in infants and children with no currently approved vaccine. The M2-1 protein is an important transcriptional antitermination factor and a potential target for viral replication inhibitor development. Hesperetin (HST) and hesperidin (HSD) are flavonoids from the flavanone group, naturally found in citrus and have, as one of their properties, antiviral activity. The present study reports on the interactions between hRSV M2-1 and these flavanones using experimental techniques in association with computational tools. STD-NMR results showed that HST and HSD bind to M2-1 by positioning their aromatic rings into the target protein binding site. Fluorescence quenching measurements revealed that HST had an interaction affinity greater than HSD towards M2-1. The thermodynamic analysis suggested that hydrogen bonds and van der Waals interactions are important for the molecular stabilization of the complexes. Computational simulations corroborated with the experimental results and indicated that the possible interaction region for the flavonoids is the AMP-binding site in M2-1. Therefore, these results point that HST and HSD bind stably to a critical region in M2-1, which is vital for its biological function, and thus might play a possible role antiviral against hRSV.
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Jespersen NE, Leyrat C, Gérard FC, Bourhis JM, Blondel D, Jamin M, Barbar E. The LC8-RavP ensemble Structure Evinces A Role for LC8 in Regulating Lyssavirus Polymerase Functionality. J Mol Biol 2019; 431:4959-4977. [PMID: 31634467 PMCID: PMC7060403 DOI: 10.1016/j.jmb.2019.10.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 10/11/2019] [Accepted: 10/11/2019] [Indexed: 12/25/2022]
Abstract
The rabies and Ebola viruses recruit the highly conserved host protein LC8 for their own reproductive success. In vivo knockouts of the LC8 recognition motif within the rabies virus phosphoprotein (RavP) result in completely nonlethal viral infections. In this work, we examine the molecular role LC8 plays in viral lethality. We show that RavP and LC8 colocalize in rabies infected cells, and that LC8 interactions are essential for efficient viral polymerase functionality. NMR, SAXS, and molecular modeling demonstrate that LC8 binding to a disordered linker adjacent to an endogenous dimerization domain results in restrictions in RavP domain orientations. The resulting ensemble structure of RavP-LC8 tetrameric complex is similar to that of a related virus phosphoprotein that does not bind LC8, suggesting that with RavP, LC8 binding acts as a switch to induce a more active conformation. The high conservation of the LC8 motif in Lyssavirus phosphoproteins and its presence in other analogous proteins such as the Ebola virus VP35 evinces a broader purpose for LC8 in regulating downstream phosphoprotein functions vital for viral replication.
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Affiliation(s)
- Nathan E Jespersen
- From the Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, USA
| | - Cedric Leyrat
- Institut de Génomique Fonctionnelle, CNRS UMR-5203 INSERM U1191, University of Montpellier, Montpellier, France
| | - Francine C Gérard
- Université Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 38000, Grenoble, France
| | - Jean-Marie Bourhis
- Université Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 38000, Grenoble, France
| | - Danielle Blondel
- Institut de Biologie Intégrative de La Cellule (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette Cedex, France
| | - Marc Jamin
- Université Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 38000, Grenoble, France
| | - Elisar Barbar
- From the Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, USA.
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15
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Acevedo OA, Díaz FE, Beals TE, Benavente FM, Soto JA, Escobar-Vera J, González PA, Kalergis AM. Contribution of Fcγ Receptor-Mediated Immunity to the Pathogenesis Caused by the Human Respiratory Syncytial Virus. Front Cell Infect Microbiol 2019; 9:75. [PMID: 30984626 PMCID: PMC6450440 DOI: 10.3389/fcimb.2019.00075] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 03/05/2019] [Indexed: 12/18/2022] Open
Abstract
The human Respiratory Syncytial Virus (hRSV) is the leading cause of severe acute lower respiratory tract infections (ALRTIs) in humans at all ages and is the main cause of hospitalization due to pneumonia, asthma, and bronchiolitis in infants. hRSV symptoms mainly develop due to an excessive host immune and inflammatory response in the respiratory tissue. hRSV infection during life is frequent and likely because of non-optimal immunological memory is developed against this virus. Vaccine development against this pathogen has been delayed after the detrimental effects produced in children by vaccination with a formalin-inactivated hRSV preparation (FI-hRSV), which caused enhanced disease upon natural viral infection. Since then, several studies have focused on understanding the mechanisms underlying such disease exacerbation. Along these lines, several studies have suggested that antibodies elicited by immunization with FI-hRSV show low neutralizing capacity and promote the formation of immune complexes containing hRSV (hRSV-ICs), which contribute to hRSV pathogenesis through the engagement of Fc gamma receptors (FcγRs) expressed on the surface of immune cells. Furthermore, a role for FcγRs is supported by studies evaluating the contribution of these molecules to hRSV-induced disease. These studies have shown that FcγRs can modulate viral clearance by the host and the inflammatory response triggered by hRSV infection. In addition, ICs can facilitate viral entry into host cells expressing FcγRs, thus extending hRSV infectivity. In this article, we discuss current knowledge relative to the contribution of hRSV-ICs and FcγRs to the pathogenesis caused by hRSV and their putative role in the exacerbation of the disease caused by this virus after FI-hRSV vaccination. A better understanding FcγRs involvement in the immune response against hRSV will contribute to the development of new prophylactic or therapeutic tools to promote virus clearance with limited inflammatory damage to the airways.
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Affiliation(s)
- Orlando A Acevedo
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Fabián E Díaz
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Tomas E Beals
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Felipe M Benavente
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Jorge A Soto
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Jorge Escobar-Vera
- Laboratorio de Genética, Departamento Biomédico, Facultad de Ciencias de la Salud, Universidad de Antofagasta, Antofagasta, Chile
| | - Pablo A González
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Alexis M Kalergis
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.,Departamento de Endocrinología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
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16
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Esperante SA, Alvarez-Paggi D, Salgueiro M, Prat Gay GD. Mechanism of Tetramer Dissociation, Unfolding, and Oligomer Assembly of Pneumovirus M2-1 Transcription Antiterminators. ACS OMEGA 2018; 3:14732-14745. [PMID: 30555987 PMCID: PMC6289497 DOI: 10.1021/acsomega.8b01600] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 10/17/2018] [Indexed: 06/09/2023]
Abstract
Among Mononegavirales, the Pneumovirus family stands out by its RNA polymerase processivity that relies on a transcription antiterminator, the M2-1 protein, which also plays a key role in viral particle assembly. Biophysical and structural evidence shows that this RNA-binding tetramer is strongly modulated by a CCCH Zn2+ binding motif. We show that while the global dissociation/unfolding free energy is 10 kcal mol-1, more stable for the respiratory syncytial virus M2-1, the human metapneumovirus (HMPV) counterpart shows a 7 kcal mol-1 higher intersubunit affinity. Removal of Zn2+ from both homologues leads to an apo-monomer of identical secondary structure that further undergoes a slow irreversible oligomerization. Mutation of the histidine residue of the Zn2+ motif to cysteine or alanine leads directly to large oligomers, strongly suggesting that metal coordination has an exquisite precision for modulating the quaternary arrangement. Zn2+ removal is very slow and requires subdenaturing concentrations of guanidine chloride, suggesting a likely local folding energy barrier. Exploring a broad combination of denaturant and ethylenediaminetetraacetic acid conditions, we showed that the metapneumovirus protein has to overcome a higher energy barrier to trigger Zn2+ removal-driven dissociation, in concordance with a slower dissociation kinetics. In silico modeling of open and close conformations for both M2-1 tetramers together with interaction energy calculations reveals that the gradual opening of protomers decreases the number of intersubunit contacts. Half of the interaction energy holding each protomer in the tetramer comes from the CCCH motif, while HMPV-M2-1 harbors additional contacts between the CCCH motif of one subunit and the core domain of a protomer located in trans, allowing the rationalization of the experimental data obtained. Overall, the evidence points at a key role of the CCCH motif in switching between structural and consequently functional alternatives of the M2-1 protein.
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17
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Selvaraj M, Yegambaram K, Todd EJAA, Richard CA, Dods RL, Pangratiou GM, Trinh CH, Moul SL, Murphy JC, Mankouri J, Éléouët JF, Barr JN, Edwards TA. The Structure of the Human Respiratory Syncytial Virus M2-1 Protein Bound to the Interaction Domain of the Phosphoprotein P Defines the Orientation of the Complex. mBio 2018; 9:e01554-18. [PMID: 30425144 PMCID: PMC6234862 DOI: 10.1128/mbio.01554-18] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 10/02/2018] [Indexed: 01/09/2023] Open
Abstract
Human respiratory syncytial virus (HRSV) is a negative-stranded RNA virus that causes a globally prevalent respiratory infection, which can cause life-threatening illness, particularly in the young, elderly, and immunocompromised. HRSV multiplication depends on replication and transcription of the HRSV genes by the virus-encoded RNA-dependent RNA polymerase (RdRp). For replication, this complex comprises the phosphoprotein (P) and the large protein (L), whereas for transcription, the M2-1 protein is also required. M2-1 is recruited to the RdRp by interaction with P and also interacts with RNA at overlapping binding sites on the M2-1 surface, such that binding of these partners is mutually exclusive. The molecular basis for the transcriptional requirement of M2-1 is unclear, as is the consequence of competition between P and RNA for M2-1 binding, which is likely a critical step in the transcription mechanism. Here, we report the crystal structure at 2.4 Å of M2-1 bound to the P interaction domain, which comprises P residues 90 to 110. The P90-110 peptide is alpha helical, and its position on the surface of M2-1 defines the orientation of the three transcriptase components within the complex. The M2-1/P interface includes ionic, hydrophobic, and hydrogen bond interactions, and the critical contribution of these contacts to complex formation was assessed using a minigenome assay. The affinity of M2-1 for RNA and P ligands was quantified using fluorescence anisotropy, which showed high-affinity RNAs could outcompete P. This has important implications for the mechanism of transcription, particularly the events surrounding transcription termination and synthesis of poly(A) sequences.IMPORTANCE Human respiratory syncytial virus (HRSV) is a leading cause of respiratory illness, particularly in the young, elderly, and immunocompromised, and has also been linked to the development of asthma. HRSV replication depends on P and L, whereas transcription also requires M2-1. M2-1 interacts with P and RNA at overlapping binding sites; while these interactions are necessary for transcriptional activity, the mechanism of M2-1 action is unclear. To better understand HRSV transcription, we solved the crystal structure of M2-1 in complex with the minimal P interaction domain, revealing molecular details of the M2-1/P interface and defining the orientation of M2-1 within the tripartite complex. The M2-1/P interaction is relatively weak, suggesting high-affinity RNAs may displace M2-1 from the complex, providing the basis for a new model describing the role of M2-1 in transcription. Recently, the small molecules quercetin and cyclopamine have been used to validate M2-1 as a drug target.
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Affiliation(s)
- Muniyandi Selvaraj
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Kavestri Yegambaram
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Eleanor J A A Todd
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Charles-Adrien Richard
- Unité de Virologie et Immunologie Moléculaires (UR892), INRA, Université Paris-Saclay, Jouy-en-Josas, France
| | - Rachel L Dods
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Georgia M Pangratiou
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Chi H Trinh
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Sophie L Moul
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - James C Murphy
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Jamel Mankouri
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Jean-François Éléouët
- Unité de Virologie et Immunologie Moléculaires (UR892), INRA, Université Paris-Saclay, Jouy-en-Josas, France
| | - John N Barr
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Thomas A Edwards
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
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18
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Phosphorylated VP30 of Marburg Virus Is a Repressor of Transcription. J Virol 2018; 92:JVI.00426-18. [PMID: 30135121 DOI: 10.1128/jvi.00426-18] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 08/06/2018] [Indexed: 12/29/2022] Open
Abstract
The filoviruses Marburg virus (MARV) and Ebola virus (EBOV) cause hemorrhagic fever in humans and nonhuman primates, with high case fatality rates. MARV VP30 is known to be phosphorylated and to interact with nucleoprotein (NP), but its role in regulation of viral transcription is disputed. Here, we analyzed phosphorylation of VP30 by mass spectrometry, which resulted in identification of multiple phosphorylated amino acids. Modeling the full-length three-dimensional structure of VP30 and mapping the identified phosphorylation sites showed that all sites lie in disordered regions, mostly in the N-terminal domain of the protein. Minigenome analysis of the identified phosphorylation sites demonstrated that phosphorylation of a cluster of amino acids at positions 46 through 53 inhibits transcription. To test the effect of VP30 phosphorylation on its interaction with other MARV proteins, coimmunoprecipitation analyses were performed. They demonstrated the involvement of VP30 phosphorylation in interaction with two other proteins of the MARV ribonucleoprotein complex, NP and VP35. To identify the role of protein phosphatase 1 (PP1) in the identified effects, a small molecule, 1E7-03, targeting a noncatalytic site of the enzyme that previously was shown to increase EBOV VP30 phosphorylation was used. Treatment of cells with 1E7-03 increased phosphorylation of VP30 at a cluster of phosphorylated amino acids from Ser-46 to Thr-53, reduced transcription of MARV minigenome, enhanced binding to NP and VP35, and dramatically reduced replication of infectious MARV particles. Thus, MARV VP30 phosphorylation can be targeted for development of future antivirals such as PP1-targeting compounds. IMPORTANCE The largest outbreak of MARV occurred in Angola in 2004 to 2005 and had a 90% case fatality rate. There are no approved treatments available for MARV. Development of antivirals as therapeutics requires a fundamental understanding of the viral life cycle. Because of the close similarity of MARV to another member of Filoviridae family, EBOV, it was assumed that the two viruses have similar mechanisms of regulation of transcription and replication. Here, characterization of the role of VP30 and its phosphorylation sites in transcription of the MARV genome demonstrated differences from those of EBOV. The identified phosphorylation sites appeared to inhibit transcription and appeared to be involved in interaction with both NP and VP35 ribonucleoproteins. A small molecule targeting PP1 inhibited transcription of the MARV genome, effectively suppressing replication of the viral particles. These data demonstrate the possibility developing antivirals based on compounds targeting PP1.
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19
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Kordyukova LV, Shtykova EV, Baratova LA, Svergun DI, Batishchev OV. Matrix proteins of enveloped viruses: a case study of Influenza A virus M1 protein. J Biomol Struct Dyn 2018; 37:671-690. [PMID: 29388479 DOI: 10.1080/07391102.2018.1436089] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Influenza A virus, a member of the Orthomyxoviridae family of enveloped viruses, is one of the human and animal top killers, and its structure and components are therefore extensively studied during the last decades. The most abundant component, M1 matrix protein, forms a matrix layer (scaffold) under the viral lipid envelope, and the functional roles as well as structural peculiarities of the M1 protein are still under heavy debate. Despite multiple attempts of crystallization, no high resolution structure is available for the full length M1 of Influenza A virus. The likely reason for the difficulties lies in the intrinsic disorder of the M1 C-terminal part preventing diffraction quality crystals to be grown. Alternative structural methods including synchrotron small-angle X-ray scattering (SAXS), atomic force microscopy, cryo-electron microscopy/tomography are therefore widely applied to understand the structure of M1, its self-association and interactions with the lipid membrane and the viral nucleocapsid. These methods reveal striking similarities in the behavior of M1 and matrix proteins of other enveloped RNA viruses, with the differences accompanied by the specific features of the viral lifecycles, thus suggesting common interaction principles and, possibly, common evolutional ancestors. The structural information on the Influenza A virus M1 protein obtained to the date strongly suggests that the intrinsic disorder in the C-terminal domain has important functional implications.
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Affiliation(s)
- Larisa V Kordyukova
- a Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University , Moscow , Russian Federation
| | - Eleonora V Shtykova
- b Shubnikov Institute of Crystallography of Federal Scientific Research Centre 'Crystallography and Photonics' of Russian Academy of Sciences , Moscow , Russian Federation.,c Semenov Institute of Chemical Physics , Russian Academy of Sciences , Moscow , Russian Federation
| | - Lyudmila A Baratova
- a Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University , Moscow , Russian Federation
| | | | - Oleg V Batishchev
- e Frumkin Institute of Physical Chemistry and Electrochemistry , Russian Academy of Sciences , Moscow , Russian Federation.,f Moscow Institute of Physics and Technology , Dolgoprudniy , Russian Federation
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20
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Molina IG, Esperante SA, Marino-Buslje C, Chemes LB, de Prat-Gay G. Cooperative RNA Recognition by a Viral Transcription Antiterminator. J Mol Biol 2018; 430:777-792. [PMID: 29414675 DOI: 10.1016/j.jmb.2018.01.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 01/29/2018] [Accepted: 01/29/2018] [Indexed: 01/18/2023]
Abstract
RNA transcription of mononegavirales decreases gradually from the 3' leader promoter toward the 5' end of the genome, due to a decay in polymerase processivity. In the respiratory syncytial virus and metapneumovirus, the M2-1 protein ensures transcription anti-termination. Despite being a homotetramer, respiratory syncytial virus M2-1 binds two molecules of RNA of 13mer or longer per tetramer, and temperature-sensitive secondary structure in the RNA ligand is unfolded by stoichiometric interaction with M2-1. Fine quantitative analysis shows positive cooperativity, indicative of conformational asymmetry in the tetramer. RNA binds to M2-1 through a fast bimolecular association followed by slow rearrangements corresponding to an induced-fit mechanism, providing a sequential description of the time events of cooperativity. The first binding event of half of the RNA molecule to one of the sites increases the affinity of the second binding event on the adjacent contacting protomer by 15-fold, product of increased effective concentration caused by the entropic link. This mechanism allows for high-affinity binding with an otherwise relaxed sequence specificity, and instead suggests a yet undefined structural recognition signature in the RNA for modulating gene transcription. This work provides a basis for an essential event for understanding transcription antitermination in pneumoviruses and its counterpart Ebola virus VP30.
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Affiliation(s)
- Ivana G Molina
- Protein Structure-Function and Engineering Laboratory, Fundación Instituto Leloir and IIBBA-CONICET, Av. Patricias Argentinas 435, 1405 Buenos Aires, Argentina
| | - Sebastian A Esperante
- Protein Structure-Function and Engineering Laboratory, Fundación Instituto Leloir and IIBBA-CONICET, Av. Patricias Argentinas 435, 1405 Buenos Aires, Argentina
| | - Cristina Marino-Buslje
- Structural Bioinformatics Unit, Fundación Instituto Leloir and IIBBA-CONICET, Av. Patricias Argentinas 435, 1405 Buenos Aires, Argentina
| | - Lucía B Chemes
- Protein Structure-Function and Engineering Laboratory, Fundación Instituto Leloir and IIBBA-CONICET, Av. Patricias Argentinas 435, 1405 Buenos Aires, Argentina.
| | - Gonzalo de Prat-Gay
- Protein Structure-Function and Engineering Laboratory, Fundación Instituto Leloir and IIBBA-CONICET, Av. Patricias Argentinas 435, 1405 Buenos Aires, Argentina.
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21
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Muniyandi S, Pangratiou G, Edwards TA, Barr JN. Structure and Function of the Human Respiratory Syncytial Virus M2-1 Protein. Subcell Biochem 2018; 88:245-260. [PMID: 29900500 DOI: 10.1007/978-981-10-8456-0_11] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Human respiratory syncytial virus (HRSV) is a non-segmented negative stranded RNA virus and is recognized as the most important viral agent of lower respiratory tract infection worldwide, responsible for up to 199,000 deaths each year. The only FDA-approved regime to prevent HRSV-mediated disease is pre-exposure administration of a humanized HRSV-specific monoclonal antibody, which although being effective, is not in widespread usage due to its cost. No HRSV vaccine exists and so there remains a strong need for alternative and complementary anti-HRSV therapies. The HRSV M2-1 protein is a transcription factor and represents an attractive target for the development of antiviral compounds, based on its essential role in the viral replication cycle. To this end, a detailed analysis of M2-1 structure and functions will aid in identifying rational targets for structure-based antiviral drug design that can be developed in future translational research. Here we present an overview of the current understanding of the structure and function of HRSV M2-1, drawing on additional information derived from its structural homologues from other related viruses.
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Affiliation(s)
- Selvaraj Muniyandi
- School of Molecular and Cellular Biology, and The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Georgia Pangratiou
- School of Molecular and Cellular Biology, and The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Thomas A Edwards
- School of Molecular and Cellular Biology, and The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - John N Barr
- School of Molecular and Cellular Biology, and The Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK.
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Molina IG, Josts I, Almeida Hernandez Y, Esperante S, Salgueiro M, Garcia Alai MM, de Prat-Gay G, Tidow H. Structure and stability of the Human respiratory syncytial virus M 2-1 RNA-binding core domain reveals a compact and cooperative folding unit. Acta Crystallogr F Struct Biol Commun 2018; 74:23-30. [PMID: 29372904 PMCID: PMC5947689 DOI: 10.1107/s2053230x17017381] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 12/04/2017] [Indexed: 11/10/2022] Open
Abstract
Human syncytial respiratory virus is a nonsegmented negative-strand RNA virus with serious implications for respiratory disease in infants, and has recently been reclassified into a new family, Pneumoviridae. One of the main reasons for this classification is the unique presence of a transcriptional antiterminator, called M2-1. The puzzling mechanism of action of M2-1, which is a rarity among antiterminators in viruses and is part of the RNA polymerase complex, relies on dissecting the structure and function of this multidomain tetramer. The RNA-binding activity is located in a monomeric globular `core' domain, a high-resolution crystal structure of which is now presented. The structure reveals a compact domain which is superimposable on the full-length M2-1 tetramer, with additional electron density for the C-terminal tail that was not observed in the previous models. Moreover, its folding stability was determined through chemical denaturation, which shows that the secondary and tertiary structure unfold concomitantly, which is indicative of a two-state equilibrium. These results constitute a further step in the understanding of this unique RNA-binding domain, for which there is no sequence or structural counterpart outside this virus family, in addition to its implications in transcription regulation and its likeliness as an antiviral target.
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Affiliation(s)
- Ivana G. Molina
- Protein Structure–Function and Engineering Laboratory, Fundación Instituto Leloir and IIBBA–CONICET, Avenida Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina
| | - Inokentijs Josts
- The Hamburg Centre for Ultrafast Imaging and Department of Chemistry, Institute for Biochemistry and Molecular Biology, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
| | - Yasser Almeida Hernandez
- The Hamburg Centre for Ultrafast Imaging and Department of Chemistry, Institute for Biochemistry and Molecular Biology, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
| | - Sebastian Esperante
- Protein Structure–Function and Engineering Laboratory, Fundación Instituto Leloir and IIBBA–CONICET, Avenida Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina
| | - Mariano Salgueiro
- Protein Structure–Function and Engineering Laboratory, Fundación Instituto Leloir and IIBBA–CONICET, Avenida Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina
| | - Maria M. Garcia Alai
- European Molecular Biology Laboratory (EMBL), Hamburg Unit, Notkestrasse 85, 22607 Hamburg, Germany
| | - Gonzalo de Prat-Gay
- Protein Structure–Function and Engineering Laboratory, Fundación Instituto Leloir and IIBBA–CONICET, Avenida Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina
| | - Henning Tidow
- The Hamburg Centre for Ultrafast Imaging and Department of Chemistry, Institute for Biochemistry and Molecular Biology, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
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Cifuentes-Muñoz N, Branttie J, Slaughter KB, Dutch RE. Human Metapneumovirus Induces Formation of Inclusion Bodies for Efficient Genome Replication and Transcription. J Virol 2017; 91:e01282-17. [PMID: 28978704 PMCID: PMC5709606 DOI: 10.1128/jvi.01282-17] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 09/25/2017] [Indexed: 12/14/2022] Open
Abstract
Human metapneumovirus (HMPV) causes significant upper and lower respiratory disease in all age groups worldwide. The virus possesses a negative-sense single-stranded RNA genome of approximately 13.3 kb encapsidated by multiple copies of the nucleoprotein (N), giving rise to helical nucleocapsids. In addition, copies of the phosphoprotein (P) and the large RNA polymerase (L) decorate the viral nucleocapsids. After viral attachment, endocytosis, and fusion mediated by the viral glycoproteins, HMPV nucleocapsids are released into the cell cytoplasm. To visualize the subsequent steps of genome transcription and replication, a fluorescence in situ hybridization (FISH) protocol was established to detect different viral RNA subpopulations in infected cells. The FISH probes were specific for detection of HMPV positive-sense RNA (+RNA) and viral genomic RNA (vRNA). Time course analysis of human bronchial epithelial BEAS-2B cells infected with HMPV revealed the formation of inclusion bodies (IBs) from early times postinfection. HMPV IBs were shown to be cytoplasmic sites of active transcription and replication, with the translation of viral proteins being closely associated. Inclusion body formation was consistent with an actin-dependent coalescence of multiple early replicative sites. Time course quantitative reverse transcription-PCR analysis suggested that the coalescence of inclusion bodies is a strategy to efficiently replicate and transcribe the viral genome. These results provide a better understanding of the steps following HMPV entry and have important clinical implications.IMPORTANCE Human metapneumovirus (HMPV) is a recently discovered pathogen that affects human populations of all ages worldwide. Reinfections are common throughout life, but no vaccines or antiviral treatments are currently available. In this work, a spatiotemporal analysis of HMPV replication and transcription in bronchial epithelial cell-derived immortal cells was performed. HMPV was shown to induce the formation of large cytoplasmic granules, named inclusion bodies, for genome replication and transcription. Unlike other cytoplasmic structures, such as stress granules and processing bodies, inclusion bodies are exclusively present in infected cells and contain HMPV RNA and proteins to more efficiently transcribe and replicate the viral genome. Though inclusion body formation is nuanced, it corresponds to a more generalized strategy used by different viruses, including filoviruses and rhabdoviruses, for genome transcription and replication. Thus, an understanding of inclusion body formation is crucial for the discovery of innovative therapeutic targets.
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Affiliation(s)
- Nicolás Cifuentes-Muñoz
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Jean Branttie
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Kerri Beth Slaughter
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Rebecca Ellis Dutch
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky, USA
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24
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Structural dissection of human metapneumovirus phosphoprotein using small angle x-ray scattering. Sci Rep 2017; 7:14865. [PMID: 29093501 PMCID: PMC5665942 DOI: 10.1038/s41598-017-14448-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 10/10/2017] [Indexed: 12/21/2022] Open
Abstract
The phosphoprotein (P) is the main and essential cofactor of the RNA polymerase (L) of non-segmented, negative‐strand RNA viruses. P positions the viral polymerase onto its nucleoprotein–RNA template and acts as a chaperone of the nucleoprotein (N), thereby preventing nonspecific encapsidation of cellular RNAs. The phosphoprotein of human metapneumovirus (HMPV) forms homotetramers composed of a stable oligomerization domain (Pcore) flanked by large intrinsically disordered regions (IDRs). Here we combined x-ray crystallography of Pcore with small angle x-ray scattering (SAXS)-based ensemble modeling of the full-length P protein and several of its fragments to provide a structural description of P that captures its dynamic character, and highlights the presence of varyingly stable structural elements within the IDRs. We discuss the implications of the structural properties of HMPV P for the assembly and functioning of the viral transcription/replication machinery.
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25
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Salunke DM, Nair DT. Macromolecular structures: Quality assessment and biological interpretation. IUBMB Life 2017; 69:563-571. [DOI: 10.1002/iub.1640] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 04/25/2017] [Indexed: 02/05/2023]
Affiliation(s)
- Dinakar M. Salunke
- International Centre for Genetic Engineering and Biotechnology; Aruna Asaf Ali Marg; New Delhi India
| | - Deepak T. Nair
- Regional Centre for Biotechnology, NCR Biotech Science Cluster; 3rd Milestone, Faridabad-Gurgaon Expressway Faridabad Haryana India
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26
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Abstract
Globally, as a leading agent of acute respiratory tract infections in children <5 years of age and the elderly, the human metapneumovirus (HMPV) has gained considerable attention. As inferred from studies comparing vaccinated and experimentally infected mice, the acquired immune response elicited by this pathogen fails to efficiently clear the virus from the airways, which leads to an exaggerated inflammatory response and lung damage. Furthermore, after disease resolution, there is a poor development of T and B cell immunological memory, which is believed to promote reinfections and viral spread in the community. In this article, we discuss the molecular mechanisms that shape the interactions of HMPV with host tissues that lead to pulmonary pathology and to the development of adaptive immunity that fails to protect against natural infections by this virus.
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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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28
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RNA Binding of Ebola Virus VP30 Is Essential for Activating Viral Transcription. J Virol 2016; 90:7481-7496. [PMID: 27279615 DOI: 10.1128/jvi.00271-16] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 05/31/2016] [Indexed: 01/17/2023] Open
Abstract
UNLABELLED The template for Ebola virus (EBOV) transcription and replication is the helical viral nucleocapsid composed of the viral negative-sense (-) RNA genome, which is complexed by the nucleoprotein (NP), VP35, polymerase L, VP24, and VP30. While viral replication is exerted by polymerase L and its cofactor VP35, EBOV mRNA synthesis is regulated by the viral nucleocapsid protein VP30, an essential EBOV-specific transcription factor. VP30 is a homohexameric phosphoprotein containing a nonconventional zinc finger. The transcriptional support activity of VP30 is strongly influenced by its phosphorylation state. We studied here how RNA binding contributed to VP30's function in transcriptional activation. Using a novel mobility shift assay and the 3'-terminal 154 nucleotides of the EBOV genome as a standard RNA substrate, we detected that RNA binding of VP30 was severely impaired by VP30 mutations that (i) destroy the protein's capability to form homohexamers, (ii) disrupt the integrity of its zinc finger domain, (iii) mimic its fully phosphorylated state, or (iv) alter the putative RNA binding region. RNA binding of the mutant VP30 proteins correlated strongly with their transcriptional support activity. Furthermore, we showed that the interaction between VP30 and the polymerase cofactor VP35 is RNA dependent, while formation of VP30 homohexamers and VP35 homotetramers is not. Our data indicate that RNA binding of VP30 is essential for its transcriptional support activity and stabilizes complexes of VP35/L polymerase with the (-) RNA template to favor productive transcriptional initiation in the presence of termination-active RNA secondary structures. IMPORTANCE Ebola virus causes severe fevers with unusually high case fatality rates. The recent outbreak of Ebola virus in West Africa claimed more than 11,000 lives and threatened to destabilize a whole region because of its dramatic effects on the public health systems. It is currently not completely understood how Ebola virus manages to balance viral transcription and replication in the infected cells. This study shows that transcriptional support activity of the Ebola virus transcription factor VP30 is highly correlated with its ability to bind viral RNA. The interaction between VP30 and VP35, the Ebola virus polymerase cofactor, is dependent on the presence of RNA as well. Our data contribute to the understanding of the dynamic interplay between nucleocapsid proteins and the viral RNA template in order to promote viral RNA synthesis.
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29
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Phosphorylation of Human Metapneumovirus M2-1 Protein Upregulates Viral Replication and Pathogenesis. J Virol 2016; 90:7323-7338. [PMID: 27252537 DOI: 10.1128/jvi.00755-16] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 05/25/2016] [Indexed: 01/02/2023] Open
Abstract
UNLABELLED Human metapneumovirus (hMPV) is a major causative agent of upper- and lower-respiratory-tract infections in infants, the elderly, and immunocompromised individuals worldwide. Like all pneumoviruses, hMPV encodes the zinc binding protein M2-1, which plays important regulatory roles in RNA synthesis. The M2-1 protein is phosphorylated, but the specific role(s) of the phosphorylation in viral replication and pathogenesis remains unknown. In this study, we found that hMPV M2-1 is phosphorylated at amino acid residues S57 and S60. Subsequent mutagenesis found that phosphorylation is not essential for zinc binding activity and oligomerization, whereas inhibition of zinc binding activity abolished the phosphorylation and oligomerization of the M2-1 protein. Using a reverse genetics system, recombinant hMPVs (rhMPVs) lacking either one or both phosphorylation sites in the M2-1 protein were recovered. These recombinant viruses had a significant decrease in both genomic RNA replication and mRNA transcription. In addition, these recombinant viruses were highly attenuated in cell culture and cotton rats. Importantly, rhMPVs lacking phosphorylation in the M2-1 protein triggered high levels of neutralizing antibody and provided complete protection against challenge with wild-type hMPV. Collectively, these data demonstrated that phosphorylation of the M2-1 protein upregulates hMPV RNA synthesis, replication, and pathogenesis in vivo IMPORTANCE The pneumoviruses include many important human and animal pathogens, such as human respiratory syncytial virus (hRSV), hMPV, bovine RSV, and avian metapneumovirus (aMPV). Among these viruses, hRSV and hMPV are the leading causes of acute respiratory tract infection in infants and children. Currently, there is no antiviral or vaccine to combat these diseases. All known pneumoviruses encode a zinc binding protein, M2-1, which is a transcriptional antitermination factor. In this work, we found that phosphorylation of M2-1 is essential for virus replication and pathogenesis in vivo Recombinant hMPVs lacking phosphorylation in M2-1 exhibited limited replication in the upper and lower respiratory tract and triggered strong protective immunity in cotton rats. This work highlights the important role of M2-1 phosphorylation in viral replication and that inhibition of M2-1 phosphorylation may serve as a novel approach to develop live attenuated vaccines as well as antiviral drugs for pneumoviruses.
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30
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Schlereth J, Grünweller A, Biedenkopf N, Becker S, Hartmann RK. RNA binding specificity of Ebola virus transcription factor VP30. RNA Biol 2016; 13:783-98. [PMID: 27315567 DOI: 10.1080/15476286.2016.1194160] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The transcription factor VP30 of the non-segmented RNA negative strand Ebola virus balances viral transcription and replication. Here, we comprehensively studied RNA binding by VP30. Using a novel VP30:RNA electrophoretic mobility shift assay, we tested truncated variants of 2 potential natural RNA substrates of VP30 - the genomic Ebola viral 3'-leader region and its complementary antigenomic counterpart (each ∼155 nt in length) - and a series of other non-viral RNAs. Based on oligonucleotide interference, the major VP30 binding region on the genomic 3'-leader substrate was assigned to the internal expanded single-stranded region (∼ nt 125-80). Best binding to VP30 was obtained with ssRNAs of optimally ∼ 40 nt and mixed base composition; underrepresentation of purines or pyrimidines was tolerated, but homopolymeric sequences impaired binding. A stem-loop structure, particularly at the 3'-end or positioned internally, supports stable binding to VP30. In contrast, dsRNA or RNAs exposing large internal loops flanked by entirely helical arms on both sides are not bound. Introduction of a 5´-Cap(0) structure impaired VP30 binding. Also, ssDNAs bind substantially weaker than isosequential ssRNAs and heparin competes with RNA for binding to VP30, indicating that ribose 2'-hydroxyls and electrostatic contacts of the phosphate groups contribute to the formation of VP30:RNA complexes. Our results indicate a rather relaxed RNA binding specificity of filoviral VP30, which largely differs from that of the functionally related transcription factor of the Paramyxoviridae which binds to ssRNAs as short as 13 nt with a preference for oligo(A) sequences.
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Affiliation(s)
- Julia Schlereth
- a Institut für Pharmazeutische Chemie, Philipps-Universität Marburg , Marburg , Germany
| | - Arnold Grünweller
- a Institut für Pharmazeutische Chemie, Philipps-Universität Marburg , Marburg , Germany
| | - Nadine Biedenkopf
- b Institut für Virologie, Philipps-Universität Marburg , Marburg , Germany
| | - Stephan Becker
- b Institut für Virologie, Philipps-Universität Marburg , Marburg , Germany
| | - Roland K Hartmann
- a Institut für Pharmazeutische Chemie, Philipps-Universität Marburg , Marburg , Germany
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31
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Salunke DM, Khan T, Gaur V, Tapryal S, Kaur K. Response to Comment on Three X-ray Crystal Structure Papers. THE JOURNAL OF IMMUNOLOGY 2016; 196:524-8. [PMID: 26747566 DOI: 10.4049/jimmunol.1501474] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
| | - Tarique Khan
- Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390
| | - Vineet Gaur
- International Institute of Molecular and Cell Biology; Warsaw 02-109, Poland
| | - Suman Tapryal
- Department of Biotechnology, Central University of Rajasthan, Bandarsindri-305817, India; and
| | - Kanwaljeet Kaur
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi-110067, India
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32
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Yabukarski F, Leyrat C, Martinez N, Communie G, Ivanov I, Ribeiro EA, Buisson M, Gerard FC, Bourhis JM, Jensen MR, Bernadó P, Blackledge M, Jamin M. Ensemble Structure of the Highly Flexible Complex Formed between Vesicular Stomatitis Virus Unassembled Nucleoprotein and its Phosphoprotein Chaperone. J Mol Biol 2016; 428:2671-94. [PMID: 27107640 DOI: 10.1016/j.jmb.2016.04.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 04/06/2016] [Accepted: 04/07/2016] [Indexed: 01/08/2023]
Abstract
Nucleocapsid assembly is an essential process in the replication of the non-segmented, negative-sense RNA viruses (NNVs). Unassembled nucleoprotein (N(0)) is maintained in an RNA-free and monomeric form by its viral chaperone, the phosphoprotein (P), forming the N(0)-P complex. Our earlier work solved the structure of vesicular stomatitis virus complex formed between an N-terminally truncated N (NΔ21) and a peptide of P (P60) encompassing the N(0)-binding site, but how the full-length P interacts with N(0) remained unknown. Here, we combine several experimental biophysical methods including size exclusion chromatography with detection by light scattering and refractometry, small-angle X-ray and neutron scattering and nuclear magnetic resonance spectroscopy with molecular dynamics simulation and computational modeling to characterize the NΔ21(0)-PFL complex formed with dimeric full-length P. We show that for multi-molecular complexes, simultaneous multiple-curve fitting using small-angle neutron scattering data collected at varying contrast levels provides additional information and can help refine structural ensembles. We demonstrate that (a) vesicular stomatitis virus PFL conserves its high flexibility within the NΔ21(0)-PFL complex and interacts with NΔ21(0) only through its N-terminal extremity; (b) each protomer of P can chaperone one N(0) client protein, leading to the formation of complexes with stoichiometries 1N:P2 and 2N:P2; and (c) phosphorylation of residues Ser60, Thr62 and Ser64 provides no additional interactions with N(0) but creates a metal binding site in PNTR. A comparison with the structures of Nipah virus and Ebola virus N(0)-P core complex suggests a mechanism for the control of nucleocapsid assembly that is common to all NNVs.
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Affiliation(s)
- Filip Yabukarski
- Institut de Biologie Structurale (IBS), CEA, CNRS, Université Grenoble Alpes, Grenoble 38044, France
| | - Cedric Leyrat
- Institut de Biologie Structurale (IBS), CEA, CNRS, Université Grenoble Alpes, Grenoble 38044, France
| | - Nicolas Martinez
- Institut de Biologie Structurale (IBS), CEA, CNRS, Université Grenoble Alpes, Grenoble 38044, France; Institut Laue Langevin, Grenoble, France
| | - Guillaume Communie
- Institut de Biologie Structurale (IBS), CEA, CNRS, Université Grenoble Alpes, Grenoble 38044, France
| | - Ivan Ivanov
- Institut de Biologie Structurale (IBS), CEA, CNRS, Université Grenoble Alpes, Grenoble 38044, France; Institut Laue Langevin, Grenoble, France
| | - Euripedes A Ribeiro
- Institut de Biologie Structurale (IBS), CEA, CNRS, Université Grenoble Alpes, Grenoble 38044, France
| | - Marlyse Buisson
- Institut de Biologie Structurale (IBS), CEA, CNRS, Université Grenoble Alpes, Grenoble 38044, France; Laboratoire de Virologie, Centre Hospitalo-Universitaire de Grenoble, Grenoble, France
| | - Francine C Gerard
- Institut de Biologie Structurale (IBS), CEA, CNRS, Université Grenoble Alpes, Grenoble 38044, France
| | - Jean-Marie Bourhis
- Institut de Biologie Structurale (IBS), CEA, CNRS, Université Grenoble Alpes, Grenoble 38044, France
| | - Malene Ringkjøbing Jensen
- Institut de Biologie Structurale (IBS), CEA, CNRS, Université Grenoble Alpes, Grenoble 38044, France
| | - Pau Bernadó
- Centre de Biochimie Structurale, INSERM U1054, CNRS UMR 5048, Université Montpellier 1 and 2, Montpellier, France
| | - Martin Blackledge
- Institut de Biologie Structurale (IBS), CEA, CNRS, Université Grenoble Alpes, Grenoble 38044, France
| | - Marc Jamin
- Institut de Biologie Structurale (IBS), CEA, CNRS, Université Grenoble Alpes, Grenoble 38044, France.
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33
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Renner M, Bertinelli M, Leyrat C, Paesen GC, Saraiva de Oliveira LF, Huiskonen JT, Grimes JM. Nucleocapsid assembly in pneumoviruses is regulated by conformational switching of the N protein. eLife 2016; 5:e12627. [PMID: 26880565 PMCID: PMC4798948 DOI: 10.7554/elife.12627] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 02/14/2016] [Indexed: 01/26/2023] Open
Abstract
Non-segmented, (-)RNA viruses cause serious human diseases. Human metapneumovirus (HMPV), an emerging pathogen of this order of viruses (Mononegavirales) is one of the main causes of respiratory tract illness in children. To help elucidate the assembly mechanism of the nucleocapsid (the viral RNA genome packaged by the nucleoprotein N) we present crystallographic structures of HMPV N in its assembled RNA-bound state and in a monomeric state, bound to the polymerase cofactor P. Our structures reveal molecular details of how P inhibits the self-assembly of N and how N transitions between the RNA-free and RNA-bound conformational state. Notably, we observe a role for the C-terminal extension of N in directly preventing premature uptake of RNA by folding into the RNA-binding cleft. Our structures suggest a common mechanism of how the growth of the nucleocapsid is orchestrated, and highlight an interaction site representing an important target for antivirals.
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Affiliation(s)
- Max Renner
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Mattia Bertinelli
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Cédric Leyrat
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Guido C Paesen
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | | | - Juha T Huiskonen
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Jonathan M Grimes
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- Diamond Light Source, Didcot, United Kingdom
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34
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Abstract
Ebolavirus is the pathogen for Ebola Hemorrhagic Fever (EHF). This disease exhibits a high fatality rate and has recently reached a historically epidemic proportion in West Africa. Out of the 5 known Ebolavirus species, only Reston ebolavirus has lost human pathogenicity, while retaining the ability to cause EHF in long-tailed macaque. Significant efforts have been spent to determine the three-dimensional (3D) structures of Ebolavirus proteins, to study their interaction with host proteins, and to identify the functional motifs in these viral proteins. Here, in light of these experimental results, we apply computational analysis to predict the 3D structures and functional sites for Ebolavirus protein domains with unknown structure, including a zinc-finger domain of VP30, the RNA-dependent RNA polymerase catalytic domain and a methyltransferase domain of protein L. In addition, we compare sequences of proteins that interact with Ebolavirus proteins from RESTV-resistant primates with those from RESTV-susceptible monkeys. The host proteins that interact with GP and VP35 show an elevated level of sequence divergence between the RESTV-resistant and RESTV-susceptible species, suggesting that they may be responsible for host specificity. Meanwhile, we detect variable positions in protein sequences that are likely associated with the loss of human pathogenicity in RESTV, map them onto the 3D structures and compare their positions to known functional sites. VP35 and VP30 are significantly enriched in these potential pathogenicity determinants and the clustering of such positions on the surfaces of VP35 and GP suggests possible uncharacterized interaction sites with host proteins that contribute to the virulence of Ebolavirus.
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Affiliation(s)
- Qian Cong
- a Departments of Biophysics and Biochemistry ; University of Texas Southwestern Medical Center at Dallas ; Dallas , TX USA
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35
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Zinc binding activity of human metapneumovirus M2-1 protein is indispensable for viral replication and pathogenesis in vivo. J Virol 2015; 89:6391-405. [PMID: 25855728 DOI: 10.1128/jvi.03488-14] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 03/30/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Human metapneumovirus (hMPV) is a member of the Pneumovirinae subfamily in the Paramyxoviridae family that causes respiratory tract infections in humans. Unlike members of the Paramyxovirinae subfamily, the polymerase complex of pneumoviruses requires an additional cofactor, the M2-1 protein, which functions as a transcriptional antitermination factor. The M2-1 protein was found to incorporate zinc ions, although the specific role(s) of the zinc binding activity in viral replication and pathogenesis remains unknown. In this study, we found that the third cysteine (C21) and the last histidine (H25) in the zinc binding motif (CCCH) of hMPV M2-1 were essential for zinc binding activity, whereas the first two cysteines (C7 and C15) play only minor or redundant roles in zinc binding. In addition, the zinc binding motif is essential for the oligomerization of M2-1. Subsequently, recombinant hMPVs (rhMPVs) carrying mutations in the zinc binding motif were recovered. Interestingly, rhMPV-C21S and -H25L mutants, which lacked zinc binding activity, had delayed replication in cell culture and were highly attenuated in cotton rats. In contrast, rhMPV-C7S and -C15S strains, which retained 60% of the zinc binding activity, replicated as efficiently as rhMPV in cotton rats. Importantly, rhMPVs that lacked zinc binding activity triggered high levels of neutralizing antibody and provided complete protection against challenge with rhMPV. Taken together, these results demonstrate that zinc binding activity is indispensable for viral replication and pathogenesis in vivo. These results also suggest that inhibition of zinc binding activity may serve as a novel approach to rationally attenuate hMPV and perhaps other pneumoviruses for vaccine purposes. IMPORTANCE The pneumoviruses include many important human and animal pathogens, such as human respiratory syncytial virus (hRSV), hMPV, bovine RSV, and avian metapneumovirus (aMPV). Among these viruses, hRSV and hMPV are the leading causes of acute respiratory tract infection in infants and children. Despite major efforts, there is no antiviral or vaccine to combat these diseases. All known pneumoviruses encode a zinc binding protein, M2-1, which is a transcriptional antitermination factor. In this work, we found that the zinc binding activity of M2-1 is essential for virus replication and pathogenesis in vivo. Recombinant hMPVs that lacked zinc binding activity were not only defective in replication in the upper and lower respiratory tract but also triggered a strong protective immunity in cotton rats. Thus, inhibition of M2-1 zinc binding activity can lead to the development of novel, live attenuated vaccines, as well as antiviral drugs for pneumoviruses.
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Radzimanowski J, Effantin G, Weissenhorn W. Conformational plasticity of the Ebola virus matrix protein. Protein Sci 2014; 23:1519-27. [PMID: 25159197 DOI: 10.1002/pro.2541] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 08/01/2014] [Accepted: 08/04/2014] [Indexed: 12/14/2022]
Abstract
Filoviruses are the causative agents of a severe and often fatal hemorrhagic fever with repeated outbreaks in Africa. They are negative sense single stranded enveloped viruses that can cross species barriers from its natural host bats to primates including humans. The small size of the genome poses limits to viral adaption, which may be partially overcome by conformational plasticity. Here we review the different conformational states of the Ebola virus (EBOV) matrix protein VP40 that range from monomers, to dimers, hexamers, and RNA-bound octamers. This conformational plasticity that is required for the viral life cycle poses a unique opportunity for development of VP40 specific drugs. Furthermore, we compare the structure to homologous matrix protein structures from Paramyxoviruses and Bornaviruses and we predict that they do not only share the fold but also the conformational flexibility of EBOV VP40.
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Affiliation(s)
- Jens Radzimanowski
- University Grenoble Alpes, UVHCI, F-38000, Grenoble, France; CNRS, UVHCI, F-38000, Grenoble, France
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Abstract
Human metapneumovirus is a major cause of respiratory tract infections worldwide. Previous reports have shown that the viral attachment glycoprotein (G) modulates innate and adaptive immune responses, leading to incomplete immunity and promoting reinfection. Using bioinformatics analyses, static light scattering, and small-angle X-ray scattering, we show that the extracellular region of G behaves as a heavily glycosylated, intrinsically disordered polymer. We discuss potential implications of these findings for the modulation of immune responses by G.
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