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Lee M, Cosic A, Tobler K, Aguilar C, Fraefel C, Eichwald C. Characterization of viroplasm-like structures by co-expression of NSP5 and NSP2 across rotavirus species A to J. J Virol 2024:e0097524. [PMID: 39194242 DOI: 10.1128/jvi.00975-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2024] [Accepted: 07/18/2024] [Indexed: 08/29/2024] Open
Abstract
Rotaviruses (RVs) are classified into nine species, A-D and F-J, with species A being the most studied. In rotavirus of species A (RVA), replication occurs in viroplasms, which are cytosolic globular inclusions composed of main building block proteins NSP5, NSP2, and VP2. The co-expression of NSP5 with either NSP2 or VP2 in uninfected cells leads to the formation of viroplasm-like structures (VLSs). Although morphologically identical to viroplasms, VLSs do not produce viral progeny but serve as excellent tools for studying complex viroplasms. A knowledge gap exists regarding non-RVA viroplasms due to the lack of specific antibodies and suitable cell culture systems. In this study, we explored the ability of NSP5 and NSP2 from non-RVA species to form VLSs. The co-expression of these two proteins led to globular VLSs in RV species A, B, D, F, G, and I, while RVC formed filamentous VLSs. The co-expression of NSP5 and NSP2 of RV species H and J did not result in VLS formation. Interestingly, NSP5 of all RV species self-oligomerizes, with the ordered C-terminal region, termed the tail, being necessary for self-oligomerization of RV species A-C and G-J. Except for NSP5 from RVJ, all NSP5 interacted with their cognate NSP2. We also found that interspecies VLS are formed between closely related RV species B with G and D with F. Additionally, VLS from RVH and RVJ formed when the tail of NSP5 RVH and RVJ was replaced by the tail of NSP5 from RVA and co-expressed with their respective NSP2. IMPORTANCE Rotaviruses (RVs) are classified into nine species, A-D and F-J, infecting mammals and birds. Due to the lack of research tools, all cumulative knowledge on RV replication is based on RV species A (RVA). The RV replication compartments are globular cytosolic structures named viroplasms, which have only been identified in RV species A. In this study, we examined the formation of viroplasm-like structures (VLSs) by the co-expression of NSP5 with NSP2 across RV species A to J. Globular VLSs formed for RV species A, B, D, F, G, and I, while RV species C formed filamentous structures. The RV species H and J did not form VLS with their cognates NSP5 and NSP2. Similar to RVA, NSP5 self-oligomerizes in all RV species, which is required for VLS formation. This study provides basic knowledge of the non-RVA replication mechanisms, which could help develop strategies to halt virus infection across RV species.
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Affiliation(s)
- Melissa Lee
- Institute of Virology, University of Zurich, Zurich, Switzerland
| | - Ariana Cosic
- Institute of Virology, University of Zurich, Zurich, Switzerland
| | - Kurt Tobler
- Institute of Virology, University of Zurich, Zurich, Switzerland
| | - Claudio Aguilar
- Institute of Virology, University of Zurich, Zurich, Switzerland
| | - Cornel Fraefel
- Institute of Virology, University of Zurich, Zurich, Switzerland
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Kordys M, Urbanowicz A. 3D Puzzle at the Nanoscale-How do RNA Viruses Self-Assemble their Capsids into Perfectly Ordered Structures. Macromol Biosci 2024:e2400088. [PMID: 38864315 DOI: 10.1002/mabi.202400088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 06/03/2024] [Indexed: 06/13/2024]
Abstract
The phenomenon of RNA virus self-organization, first observed in the mid-20th century in tobacco mosaic virus, is the subject of extensive research. Efforts to comprehend this process intensify due to its potential for producing vaccines or antiviral compounds as well as nanocarriers and nanotemplates. However, direct observation of the self-assembly is hindered by its prevalence within infected host cells. One of the approaches involves in vitro and in silico research using model viruses featuring a ssRNA(+) genome enclosed within a capsid made up of a single type protein. While various pathways are proposed based on these studies, their relevance in vivo remains uncertain. On the other hand, the development of advanced microscopic methods provide insights into the events within living cells, where following viral infection, specialized compartments form to facilitate the creation of nascent virions. Intriguingly, a growing body of evidence indicates that the primary function of packaging signals in viral RNA is to effectively initiate the virion self-assembly. This is in contrast to earlier opinions suggesting a role in marking RNA for encapsidation. Another noteworthy observation is that many viruses undergo self-assembly within membraneless liquid organelles, which are specifically induced by viral proteins.
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Affiliation(s)
- Martyna Kordys
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego Str. 12/14, Poznan, 61-704, Poland
| | - Anna Urbanowicz
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego Str. 12/14, Poznan, 61-704, Poland
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3
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Maio N, Heffner AL, Rouault TA. Iron‑sulfur clusters in viral proteins: Exploring their elusive nature, roles and new avenues for targeting infections. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119723. [PMID: 38599324 PMCID: PMC11139609 DOI: 10.1016/j.bbamcr.2024.119723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 03/13/2024] [Accepted: 04/01/2024] [Indexed: 04/12/2024]
Abstract
Viruses have evolved complex mechanisms to exploit host factors for replication and assembly. In response, host cells have developed strategies to block viruses, engaging in a continuous co-evolutionary battle. This dynamic interaction often revolves around the competition for essential resources necessary for both host cell and virus replication. Notably, iron, required for the biosynthesis of several cofactors, including iron‑sulfur (FeS) clusters, represents a critical element in the ongoing competition for resources between infectious agents and host. Although several recent studies have identified FeS cofactors at the core of virus replication machineries, our understanding of their specific roles and the cellular processes responsible for their incorporation into viral proteins remains limited. This review aims to consolidate our current knowledge of viral components that have been characterized as FeS proteins and elucidate how viruses harness these versatile cofactors to their benefit. Its objective is also to propose that viruses may depend on incorporation of FeS cofactors more extensively than is currently known. This has the potential to revolutionize our understanding of viral replication, thereby carrying significant implications for the development of strategies to target infections.
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Affiliation(s)
- Nunziata Maio
- Molecular Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA.
| | - Audrey L Heffner
- Molecular Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA; Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Tracey A Rouault
- Molecular Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA
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4
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Vetter J, Papa G, Tobler K, Rodriguez JM, Kley M, Myers M, Wiesendanger M, Schraner EM, Luque D, Burrone OR, Fraefel C, Eichwald C. The recruitment of TRiC chaperonin in rotavirus viroplasms correlates with virus replication. mBio 2024; 15:e0049924. [PMID: 38470055 PMCID: PMC11005421 DOI: 10.1128/mbio.00499-24] [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: 02/19/2024] [Accepted: 02/22/2024] [Indexed: 03/13/2024] Open
Abstract
Rotavirus (RV) replication takes place in the viroplasms, cytosolic inclusions that allow the synthesis of virus genome segments and their encapsidation in the core shell, followed by the addition of the second layer of the virion. The viroplasms are composed of several viral proteins, including NSP5, which serves as the main building block. Microtubules, lipid droplets, and miRNA-7 are among the host components recruited in viroplasms. We investigated the interaction between RV proteins and host components of the viroplasms by performing a pull-down assay of lysates from RV-infected cells expressing NSP5-BiolD2. Subsequent tandem mass spectrometry identified all eight subunits of the tailless complex polypeptide I ring complex (TRiC), a cellular chaperonin responsible for folding at least 10% of the cytosolic proteins. Our confirmed findings reveal that TRiC is brought into viroplasms and wraps around newly formed double-layered particles. Chemical inhibition of TRiC and silencing of its subunits drastically reduced virus progeny production. Through direct RNA sequencing, we show that TRiC is critical for RV replication by controlling dsRNA genome segment synthesis, particularly negative-sense single-stranded RNA. Importantly, cryo-electron microscopy analysis shows that TRiC inhibition results in defective virus particles lacking genome segments and polymerase complex (VP1/VP3). Moreover, TRiC associates with VP2 and NSP5 but not with VP1. Also, VP2 is shown to be essential for recruiting TRiC in viroplasms and preserving their globular morphology. This study highlights the essential role of TRiC in viroplasm formation and in facilitating virion assembly during the RV life cycle. IMPORTANCE The replication of rotavirus takes place in cytosolic inclusions termed viroplasms. In these inclusions, the distinct 11 double-stranded RNA genome segments are co-packaged to complete a genome in newly generated virus particles. In this study, we show for the first time that the tailless complex polypeptide I ring complex (TRiC), a cellular chaperonin responsible for the folding of at least 10% of the cytosolic proteins, is a component of viroplasms and is required for the synthesis of the viral negative-sense single-stranded RNA. Specifically, TRiC associates with NSP5 and VP2, the cofactor involved in RNA replication. Our study adds a new component to the current model of rotavirus replication, where TRiC is recruited to viroplasms to assist replication.
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Affiliation(s)
- Janine Vetter
- Institute of Virology, University of Zurich, Zurich, Switzerland
| | - Guido Papa
- Molecular Immunology Lab, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Kurt Tobler
- Institute of Virology, University of Zurich, Zurich, Switzerland
| | - Javier M. Rodriguez
- Department of Structure of Macromolecules, Centro Nacional de Biotecnología/CSIC, Cantoblanco, Madrid, Spain
| | - Manuel Kley
- Institute of Virology, University of Zurich, Zurich, Switzerland
| | - Michael Myers
- Proteomics Lab, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Mahesa Wiesendanger
- Institute of Virology, University of Zurich, Zurich, Switzerland
- Institute of Veterinary Anatomy, University of Zurich, Zurich, Switzerland
| | - Elisabeth M. Schraner
- Institute of Virology, University of Zurich, Zurich, Switzerland
- Institute of Veterinary Anatomy, University of Zurich, Zurich, Switzerland
| | - Daniel Luque
- School of Biomedical Sciences, The University of New South Wales, Sydney, New South Wales, Australia
- Electron Microscope Unit, Mark Wainwright Analytical Centre, The University of New South Wales, Sydney, New South Wales, Australia
| | - Oscar R. Burrone
- Molecular Immunology Lab, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Cornel Fraefel
- Institute of Virology, University of Zurich, Zurich, Switzerland
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5
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Geiger F, Acker J, Papa G, Wang X, Arter WE, Saar KL, Erkamp NA, Qi R, Bravo JPK, Strauss S, Krainer G, Burrone OR, Jungmann R, Knowles TPJ, Engelke H, Borodavka A. Liquid-liquid phase separation underpins the formation of replication factories in rotaviruses. EMBO J 2021; 40:e107711. [PMID: 34524703 PMCID: PMC8561643 DOI: 10.15252/embj.2021107711] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 08/23/2021] [Accepted: 08/27/2021] [Indexed: 12/29/2022] Open
Abstract
RNA viruses induce the formation of subcellular organelles that provide microenvironments conducive to their replication. Here we show that replication factories of rotaviruses represent protein-RNA condensates that are formed via liquid-liquid phase separation of the viroplasm-forming proteins NSP5 and rotavirus RNA chaperone NSP2. Upon mixing, these proteins readily form condensates at physiologically relevant low micromolar concentrations achieved in the cytoplasm of virus-infected cells. Early infection stage condensates could be reversibly dissolved by 1,6-hexanediol, as well as propylene glycol that released rotavirus transcripts from these condensates. During the early stages of infection, propylene glycol treatments reduced viral replication and phosphorylation of the condensate-forming protein NSP5. During late infection, these condensates exhibited altered material properties and became resistant to propylene glycol, coinciding with hyperphosphorylation of NSP5. Some aspects of the assembly of cytoplasmic rotavirus replication factories mirror the formation of other ribonucleoprotein granules. Such viral RNA-rich condensates that support replication of multi-segmented genomes represent an attractive target for developing novel therapeutic approaches.
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Affiliation(s)
- Florian Geiger
- Department of ChemistryLudwig‐Maximilians‐Universität MünchenMunichGermany
| | - Julia Acker
- Department of BiochemistryUniversity of CambridgeCambridgeUK
| | - Guido Papa
- International Center for Genetic Engineering and BiotechnologyTriesteItaly
- Present address:
Medical Research Council Laboratory of Molecular Biology (MRC LMB)CambridgeUK
| | - Xinyu Wang
- Department of BiochemistryUniversity of CambridgeCambridgeUK
| | | | - Kadi L Saar
- Department of ChemistryUniversity of CambridgeCambridgeUK
| | - Nadia A Erkamp
- Department of ChemistryUniversity of CambridgeCambridgeUK
| | - Runzhang Qi
- Department of ChemistryUniversity of CambridgeCambridgeUK
| | - Jack PK Bravo
- Department of BiochemistryUniversity of CambridgeCambridgeUK
- Present address:
Department of Molecular BiosciencesUniversity of Texas at AustinAustinTXUSA
| | - Sebastian Strauss
- Department of Physics and Center for NanoscienceMax Planck Institute of BiochemistryMunichGermany
| | - Georg Krainer
- Department of ChemistryUniversity of CambridgeCambridgeUK
| | - Oscar R Burrone
- International Center for Genetic Engineering and BiotechnologyTriesteItaly
| | - Ralf Jungmann
- Department of Physics and Center for NanoscienceMax Planck Institute of BiochemistryMunichGermany
| | | | - Hanna Engelke
- Department of ChemistryLudwig‐Maximilians‐Universität MünchenMunichGermany
- Institute of Pharmaceutical SciencesKarl‐Franzens‐Universität GrazGrazAustria
| | - Alexander Borodavka
- Department of ChemistryLudwig‐Maximilians‐Universität MünchenMunichGermany
- Department of BiochemistryUniversity of CambridgeCambridgeUK
- Department of Physics and Center for NanoscienceMax Planck Institute of BiochemistryMunichGermany
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6
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Papa G, Borodavka A, Desselberger U. Viroplasms: Assembly and Functions of Rotavirus Replication Factories. Viruses 2021; 13:1349. [PMID: 34372555 PMCID: PMC8310052 DOI: 10.3390/v13071349] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 07/08/2021] [Accepted: 07/09/2021] [Indexed: 02/07/2023] Open
Abstract
Viroplasms are cytoplasmic, membraneless structures assembled in rotavirus (RV)-infected cells, which are intricately involved in viral replication. Two virus-encoded, non-structural proteins, NSP2 and NSP5, are the main drivers of viroplasm formation. The structures (as far as is known) and functions of these proteins are described. Recent studies using plasmid-only-based reverse genetics have significantly contributed to elucidation of the crucial roles of these proteins in RV replication. Thus, it has been recognized that viroplasms resemble liquid-like protein-RNA condensates that may be formed via liquid-liquid phase separation (LLPS) of NSP2 and NSP5 at the early stages of infection. Interactions between the RNA chaperone NSP2 and the multivalent, intrinsically disordered protein NSP5 result in their condensation (protein droplet formation), which plays a central role in viroplasm assembly. These droplets may provide a unique molecular environment for the establishment of inter-molecular contacts between the RV (+)ssRNA transcripts, followed by their assortment and equimolar packaging. Future efforts to improve our understanding of RV replication and genome assortment in viroplasms should focus on their complex molecular composition, which changes dynamically throughout the RV replication cycle, to support distinct stages of virion assembly.
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Affiliation(s)
- Guido Papa
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK;
| | | | - Ulrich Desselberger
- Department of Medicine, Addenbrooke’s Hospital, University of Cambridge, Cambridge CB2 0QQ, UK
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7
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Chávez-Maya F, García-Espinosa G, López-Arellano ME, Padilla-Noriega L. Mutations in the VP2 gene of rotavirus associated with benzimidazole sensitivity. Virus Res 2020; 291:198189. [PMID: 33049307 DOI: 10.1016/j.virusres.2020.198189] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 08/23/2020] [Accepted: 10/05/2020] [Indexed: 12/15/2022]
Abstract
Rotavirus species A (RVA) is the etiological agent of acute gastroenteritis in young individuals of various animal species, including humans. Vaccination has helped to reduce the impact of these viruses on humans and some species of domestic mammals, but they do not confer complete immunity, so antirotavirus agents are another important control option. In this study, millimolar concentrations of benzimidazole inhibited the replication of the Rhesus rotavirus (RRV) strain of RVA. Two mutants partially resistant to the inhibitory effect of benzimidazole were independently selected, and their genomes and those of their parental strains were fully sequenced. Most (7/11) mutations occurred in the gene that encodes the VP2 protein, and similarly most of the missense mutations (5/9), including the only one shared by the two mutants (G2,414 → R[G/A], D800 N), occurred in the VP2 gene. Our results identify the VP2 gene as the primary target affected by benzimidazole.
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Affiliation(s)
- Fernando Chávez-Maya
- Departamento de Medicina y Zootecnia de Aves, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Coyoacán 04510, Ciudad de México, Mexico.
| | - Gary García-Espinosa
- Departamento de Medicina y Zootecnia de Aves, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Coyoacán 04510, Ciudad de México, Mexico.
| | - María Eugenia López-Arellano
- Departamento de Helmintología, Centro Nacional de Investigación Disciplinaria en Salud Animal e Inocuidad, INIFAP-México, Jiutepec 62550, Morelos, Mexico.
| | - Luis Padilla-Noriega
- Departamento de Microbiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad Universitaria, edificio A, primer piso, Coyoacán 04510, Ciudad de México, Mexico.
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8
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Conserved Rotavirus NSP5 and VP2 Domains Interact and Affect Viroplasm. J Virol 2020; 94:JVI.01965-19. [PMID: 31915278 DOI: 10.1128/jvi.01965-19] [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: 11/21/2019] [Accepted: 12/21/2019] [Indexed: 01/15/2023] Open
Abstract
One step of the life cycle common to all rotaviruses (RV) studied so far is the formation of viroplasms, membrane-less cytosolic inclusions providing a microenvironment for early morphogenesis and RNA replication. Viroplasm-like structures (VLS) are simplified viroplasm models consisting of complexes of nonstructural protein 5 (NSP5) with the RV core shell VP2 or NSP2. We identified and characterized the domains required for NSP5-VP2 interaction and VLS formation. VP2 mutations L124A, V865A, and I878A impaired both NSP5 hyperphosphorylation and NSP5/VP2 VLS formation. Moreover, NSP5-VP2 interaction does not depend on NSP5 hyperphosphorylation. The NSP5 tail region is required for VP2 interaction. Notably, VP2 L124A expression acts as a dominant-negative element by disrupting the formation of either VLS or viroplasms and blocking RNA synthesis. In silico analyses revealed that VP2 L124, V865, and I878 are conserved among RV species A to H. Detailed knowledge of the protein interaction interface required for viroplasm formation may facilitate the design of broad-spectrum antivirals to block RV replication.IMPORTANCE Alternative treatments to combat rotavirus infection are a requirement for susceptible communities where vaccines cannot be applied. This demand is urgent for newborn infants, immunocompromised patients, adults traveling to high-risk regions, and even for the livestock industry. Aside from structural and physiological divergences among RV species studied before now, all replicate within cytosolic inclusions termed viroplasms. These inclusions are composed of viral and cellular proteins and viral RNA. Viroplasm-like structures (VLS), composed of RV protein NSP5 with either NSP2 or VP2, are models for investigating viroplasms. In this study, we identified a conserved amino acid in the VP2 protein, L124, necessary for its interaction with NSP5 and the formation of both VLSs and viroplasms. As RV vaccines cover a narrow range of viral strains, the identification of VP2 L124 residue lays the foundations for the design of drugs that specifically block NSP5-VP2 interaction as a broad-spectrum RV antiviral.
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9
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Abid N, Chillemi G, Salemi M. Coding-Gene Coevolution Analysis of Rotavirus Proteins: A Bioinformatics and Statistical Approach. Genes (Basel) 2019; 11:genes11010028. [PMID: 31878331 PMCID: PMC7016848 DOI: 10.3390/genes11010028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 12/10/2019] [Accepted: 12/19/2019] [Indexed: 01/12/2023] Open
Abstract
Rotavirus remains a major cause of diarrhea in infants and young children worldwide. The permanent emergence of new genotypes puts the potential effectiveness of vaccines under serious question. The distribution of unusual genotypes subject to viral fitness is influenced by interactions among viral proteins. The present work aimed at analyzing the genetic constellation and the coevolution of rotavirus coding genes for the available rotavirus genotypes. Seventy-two full genome sequences of different genetic constellations were analyzed using a genetic algorithm. The results revealed an extensive genome-wide covariance network among the 12 viral proteins. Altogether, the emergence of new genotypes represents a challenge to the outcome and success of vaccination and the coevolutionary analysis of rotavirus proteins may boost efforts to better understand the interaction networks of proteins during viral replication/transcription.
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Affiliation(s)
- Nabil Abid
- Laboratory of Transmissible Diseases and Biological Active Substances LR99ES27, Faculty of Pharmacy, University of Monastir, Rue Ibn Sina, Monastir 5000, Tunisia
- High Institute of Biotechnology of Sidi Thabet, Department of Biotechnology, University Manouba, BP-66, Ariana-Tunis 2020, Tunisia
- Correspondence: or ; Tel.: +216-92–974-000
| | - Giovanni Chillemi
- Department for Innovation in Biological, Agro-food and Forest systems, DIBAF, University of Tuscia, via S. Camillo de Lellis s.n.c., 01100 Viterbo, Italy;
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, IBIOM, CNR, Via Giovanni Amendola, 122/O, 70126 Bari, Italy
| | - Marco Salemi
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida College of Medicine, Emerging Pathogens Institute, P.O. Box 100009, Gainesville, FL 32610-3633, USA;
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10
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Garcés Suárez Y, Martínez JL, Torres Hernández D, Hernández HO, Pérez-Delgado A, Méndez M, Wood CD, Rendon-Mancha JM, Silva-Ayala D, López S, Guerrero A, Arias CF. Nanoscale organization of rotavirus replication machineries. eLife 2019; 8:e42906. [PMID: 31343403 PMCID: PMC6692110 DOI: 10.7554/elife.42906] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 07/22/2019] [Indexed: 12/18/2022] Open
Abstract
Rotavirus genome replication and assembly take place in cytoplasmic electron dense inclusions termed viroplasms (VPs). Previous conventional optical microscopy studies observing the intracellular distribution of rotavirus proteins and their organization in VPs have lacked molecular-scale spatial resolution, due to inherent spatial resolution constraints. In this work we employed super-resolution microscopy to reveal the nanometric-scale organization of VPs formed during rotavirus infection, and quantitatively describe the structural organization of seven viral proteins within and around the VPs. The observed viral components are spatially organized as five concentric layers, in which NSP5 localizes at the center of the VPs, surrounded by a layer of NSP2 and NSP4 proteins, followed by an intermediate zone comprised of the VP1, VP2, VP6. In the outermost zone, we observed a ring of VP4 and finally a layer of VP7. These findings show that rotavirus VPs are highly organized organelles.
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Affiliation(s)
- Yasel Garcés Suárez
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de BiotecnologíaUniversidad Nacional Autónoma de MéxicoMexico CityMexico
| | - Jose L Martínez
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de BiotecnologíaUniversidad Nacional Autónoma de MéxicoMexico CityMexico
| | - David Torres Hernández
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de BiotecnologíaUniversidad Nacional Autónoma de MéxicoMexico CityMexico
- Laboratorio Nacional de Microscopía Avanzada, Instituto de BiotecnologíaUniversidad Nacional Autónoma de MéxicoMexico CityMexico
| | - Haydee Olinca Hernández
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de BiotecnologíaUniversidad Nacional Autónoma de MéxicoMexico CityMexico
- Laboratorio Nacional de Microscopía Avanzada, Instituto de BiotecnologíaUniversidad Nacional Autónoma de MéxicoMexico CityMexico
| | - Arianna Pérez-Delgado
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de BiotecnologíaUniversidad Nacional Autónoma de MéxicoMexico CityMexico
| | - Mayra Méndez
- Centro de Investigación en Ciencias, Instituto de Investigación en Ciencias Básicas y AplicadasUniversidad Autónoma del Estado de MorelosCuernavacaMexico
| | - Christopher D Wood
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de BiotecnologíaUniversidad Nacional Autónoma de MéxicoMexico CityMexico
- Laboratorio Nacional de Microscopía Avanzada, Instituto de BiotecnologíaUniversidad Nacional Autónoma de MéxicoMexico CityMexico
| | - Juan Manuel Rendon-Mancha
- Centro de Investigación en Ciencias, Instituto de Investigación en Ciencias Básicas y AplicadasUniversidad Autónoma del Estado de MorelosCuernavacaMexico
| | - Daniela Silva-Ayala
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de BiotecnologíaUniversidad Nacional Autónoma de MéxicoMexico CityMexico
| | - Susana López
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de BiotecnologíaUniversidad Nacional Autónoma de MéxicoMexico CityMexico
| | - Adán Guerrero
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de BiotecnologíaUniversidad Nacional Autónoma de MéxicoMexico CityMexico
- Laboratorio Nacional de Microscopía Avanzada, Instituto de BiotecnologíaUniversidad Nacional Autónoma de MéxicoMexico CityMexico
| | - Carlos F Arias
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de BiotecnologíaUniversidad Nacional Autónoma de MéxicoMexico CityMexico
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11
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Jiménez-Zaragoza M, Yubero MP, Martín-Forero E, Castón JR, Reguera D, Luque D, de Pablo PJ, Rodríguez JM. Biophysical properties of single rotavirus particles account for the functions of protein shells in a multilayered virus. eLife 2018; 7:37295. [PMID: 30201094 PMCID: PMC6133545 DOI: 10.7554/elife.37295] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 08/01/2018] [Indexed: 12/27/2022] Open
Abstract
The functions performed by the concentric shells of multilayered dsRNA viruses require specific protein interactions that can be directly explored through their mechanical properties. We studied the stiffness, breaking force, critical strain and mechanical fatigue of individual Triple, Double and Single layered rotavirus (RV) particles. Our results, in combination with Finite Element simulations, demonstrate that the mechanics of the external layer provides the resistance needed to counteract the stringent conditions of extracellular media. Our experiments, in combination with electrostatic analyses, reveal a strong interaction between the two outer layers and how it is suppressed by the removal of calcium ions, a key step for transcription initiation. The intermediate layer presents weak hydrophobic interactions with the inner layer that allow the assembly and favor the conformational dynamics needed for transcription. Our work shows how the biophysical properties of the three shells are finely tuned to produce an infective RV virion.
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Affiliation(s)
- Manuel Jiménez-Zaragoza
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, Spain
| | - Marina Pl Yubero
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, Spain
| | | | - Jose R Castón
- Department of Structure of Macromolecules, Centro Nacional de Biotecnología/CSIC, Madrid, Spain
| | - David Reguera
- Departament de Física de la Matèria Condensada, Facultat de Física, Universitat de Barcelona, Barcelona, Spain
| | - Daniel Luque
- Centro Nacional de Microbiología/ISCIII, Majadahonda, Spain
| | - Pedro J de Pablo
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, Spain.,Instituto de Física de la Materia Condensada (IFIMAC), Universidad Autónoma de Madrid, Madrid, Spain
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12
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Abstract
In infected cells rotavirus (RV) replicates in viroplasms, cytosolic structures that require a stabilized microtubule (MT) network for their assembly, maintenance of the structure and perinuclear localization. Therefore, we hypothesized that RV could interfere with the MT-breakdown that takes place in mitosis during cell division. Using synchronized RV-permissive cells, we show that RV infection arrests the cell cycle in S/G2 phase, thus favoring replication by improving viroplasms formation, viral protein translation, and viral assembly. The arrest in S/G2 phase is independent of the host or viral strain and relies on active RV replication. RV infection causes cyclin B1 down-regulation, consistent with blocking entry into mitosis. With the aid of chemical inhibitors, the cytoskeleton network was linked to specific signaling pathways of the RV-induced cell cycle arrest. We found that upon RV infection Eg5 kinesin was delocalized from the pericentriolar region to the viroplasms. We used a MA104-Fucci system to identify three RV proteins (NSP3, NSP5, and VP2) involved in cell cycle arrest in the S-phase. Our data indicate that there is a strong correlation between the cell cycle arrest and RV replication.
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13
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The N-Terminal of Aquareovirus NS80 Is Required for Interacting with Viral Proteins and Viral Replication. PLoS One 2016; 11:e0148550. [PMID: 26871941 PMCID: PMC4752286 DOI: 10.1371/journal.pone.0148550] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 01/19/2016] [Indexed: 11/21/2022] Open
Abstract
Reovirus replication and assembly occurs within viral inclusion bodies that formed in specific intracellular compartments of cytoplasm in infected cells. Previous study indicated that aquareovirus NS80 is able to form inclusion bodies, and also can retain viral proteins within its inclusions. To better understand how NS80 performed in viral replication and assembly, the functional regions of NS80 associated with other viral proteins in aquareovirus replication were investigated in this study. Deletion mutational analysis and rotavirus NSP5-based protein association platform were used to detect association regions. Immunofluorescence images indicated that different N-terminal regions of NS80 could associate with viral proteins VP1, VP4, VP6 and NS38. Further co-immunoprecipitation analysis confirmed the interaction between VP1, VP4, VP6 or NS38 with different regions covering the N-terminal amino acid (aa, 1–471) of NS80, respectively. Moreover, removal of NS80 N-terminal sequences required for interaction with proteins VP1, VP4, VP6 or NS38 not only prevented the capacity of NS80 to support viral replication in NS80 shRNA-based replication complementation assays, but also inhibited the expression of aquareovirus proteins, suggesting that N-terminal regions of NS80 are necessary for viral replication. These results provided a foundational basis for further understanding the role of NS80 in viral replication and assembly during aquareovirus infection.
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14
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Desselberger U. Rotaviruses. Virus Res 2014; 190:75-96. [DOI: 10.1016/j.virusres.2014.06.016] [Citation(s) in RCA: 240] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 06/26/2014] [Accepted: 06/26/2014] [Indexed: 01/12/2023]
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15
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Abstract
UNLABELLED Replication and packaging of the rotavirus genome occur in cytoplasmic compartments called viroplasms, which form during virus infection. These processes are orchestrated by yet-to-be-understood complex networks of interactions involving nonstructural proteins (NSPs) 2, 5, and 6 and structural proteins (VPs) 1, 2, 3, and 6. The multifunctional enzyme NSP2, an octamer with RNA binding activity, is critical for viroplasm formation with its binding partner, NSP5, and for genome replication/packaging through its interactions with replicating RNA, the viral polymerase VP1, and the inner core protein VP2. Using isothermal calorimetry, biolayer interferometry, and peptide array screening, we examined the interactions between NSP2, VP1, VP2, NSP5, and NSP6. These studies provide the first evidence that NSP2 can directly bind to VP1, VP2, and NSP6, in addition to the previously known binding to NSP5. The interacting sites identified from reciprocal peptide arrays were found to be in close proximity to the RNA template entry and double-stranded RNA (dsRNA) exit tunnels of VP1 and near the catalytic cleft and RNA-binding grooves of NSP2; these sites are consistent with the proposed role of NSP2 in facilitating dsRNA synthesis by VP1. Peptide screening of VP2 identified NSP2-binding sites in the regions close to the intersubunit junctions, suggesting that NSP2 binding could be a regulatory mechanism for preventing the premature self-assembly of VP2. The binding sites on NSP2 for NSP6 were found to overlap that of VP1, and the NSP5-binding sites overlap those of VP2 and VP1, suggesting that interaction of these proteins with NSP2 is likely spatially and/or temporally regulated. IMPORTANCE Replication and packaging of the rotavirus genome occur in cytoplasmic compartments called viroplasms that form during virus infection and are orchestrated by complex networks of interactions involving nonstructural proteins (NSPs) and structural proteins (VPs). A multifunctional RNA-binding NSP2 octamer with nucleotidyl phosphatase activity is central to viroplasm formation and RNA replication. Here we provide the first evidence that NSP2 can directly bind to VP1, VP2, and NSP6, in addition to the previously known binding to NSP5. The interacting sites identified from peptide arrays are consistent with the proposed role of NSP2 in facilitating dsRNA synthesis by VP1 and also point to NSP2's possible role in preventing the premature self-assembly of VP2 cores. Our findings lead us to propose that the NSP2 octamer with multiple enzymatic activities is a principal regulator of viroplasm formation, recruitment of viral proteins into the viroplasms, and possibly genome replication.
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16
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Revisiting the genome packaging in viruses with lessons from the "Giants". Virology 2014; 466-467:15-26. [PMID: 24998349 DOI: 10.1016/j.virol.2014.06.022] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 06/16/2014] [Accepted: 06/17/2014] [Indexed: 11/23/2022]
Abstract
Genome encapsidation is an essential step in the life cycle of viruses. Viruses either use some of the most powerful ATP-dependent motors to compel the genetic material into the preformed capsid or make use of the positively charged proteins to bind and condense the negatively charged genome in an energy-independent manner. While the former is a hallmark of large DNA viruses, the latter is commonly seen in small DNA and RNA viruses. Discoveries of many complex giant viruses such as mimivirus, megavirus, pandoravirus, etc., belonging to the nucleo-cytoplasmic large DNA virus (NCLDV) superfamily have changed the perception of genome packaging in viruses. From what little we have understood so far, it seems that the genome packaging mechanism in NCLDVs has nothing in common with other well-characterized viral packaging systems such as the portal-terminase system or the energy-independent system. Recent findings suggest that in giant viruses, the genome segregation and packaging processes are more intricately coupled than those of other viral systems. Interestingly, giant viral packaging systems also seem to possess features that are analogous to bacterial and archaeal chromosome segregation. Although there is a lot of diversity in terms of host range, type of genome, and genome size among viruses, they all seem to use three major types of independent innovations to accomplish genome encapsidation. Here, we have made an attempt to comprehensively review all the known viral genome packaging systems, including the one that is operative in giant viruses, by proposing a simple and expanded classification system that divides the viral packaging systems into three large groups (types I-III) on the basis of the mechanism employed and the relatedness of the major packaging proteins. Known variants within each group have been further classified into subgroups to reflect their unique adaptations.
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A novel form of rotavirus NSP2 and phosphorylation-dependent NSP2-NSP5 interactions are associated with viroplasm assembly. J Virol 2013; 88:786-98. [PMID: 24198401 DOI: 10.1128/jvi.03022-13] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Rotavirus (RV) replication occurs in cytoplasmic inclusions called viroplasms whose formation requires the interactions of RV proteins NSP2 and NSP5; however, the specific role(s) of NSP2 in viroplasm assembly remains largely unknown. To study viroplasm formation in the context of infection, we characterized two new monoclonal antibodies (MAbs) specific for NSP2. These MAbs show high-affinity binding to NSP2 and differentially recognize distinct pools of NSP2 in RV-infected cells; a previously unrecognized cytoplasmically dispersed NSP2 (dNSP2) is detected by an N-terminal binding MAb, and previously known viroplasmic NSP2 (vNSP2) is detected by a C-terminal binding MAb. Kinetic experiments in RV-infected cells demonstrate that dNSP2 is associated with NSP5 in nascent viroplasms that lack vNSP2. As viroplasms mature, dNSP2 remains in viroplasms, and the amount of diffuse cytoplasmic dNSP2 increases. vNSP2 is detected in increasing amounts later in infection in the maturing viroplasm, suggesting a conversion of dNSP2 into vNSP2. Immunoprecipitation experiments and reciprocal Western blot analysis confirm that there are two different forms of NSP2 that assemble in complexes with NSP5, VP1, VP2, and tubulin. dNSP2 associates with hypophosphorylated NSP5 and acetylated tubulin, which is correlated with stabilized microtubules, while vNSP2 associates with hyperphosphorylated NSP5. Mass spectroscopy analysis of NSP2 complexes immunoprecipitated from RV-infected cell lysates show both forms of NSP2 are phosphorylated, with a greater proportion of vNSP2 being phosphorylated compared to dNSP2. Together, these data suggest that dNSP2 interacts with viral proteins, including hypophosphorylated NSP5, to initiate viroplasm formation, while viroplasm maturation includes phosphorylation of NSP5 and vNSP2.
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18
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Desselberger U, Richards J, Tchertanov L, Lepault J, Lever A, Burrone O, Cohen J. Further characterisation of rotavirus cores: Ss(+)RNAs can be packaged in vitro but packaging lacks sequence specificity. Virus Res 2013; 178:252-63. [PMID: 24091366 PMCID: PMC3854842 DOI: 10.1016/j.virusres.2013.09.034] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 09/12/2013] [Accepted: 09/23/2013] [Indexed: 12/15/2022]
Abstract
Rotavirus (RV) cores were released from double-layered particles (DLPs) by high concentrations of CaCl2, purified and 'opened' by treatment with EDTA or EGTA. Under appropriate in vitro conditions DLPs have been shown to have transcriptase and 'open cores' replicase activity. Furthermore, it has been demonstrated that transcriptase activity and infectivity of native cores can be restored by transcapsidation with VP6, VP7 and VP4. The missing link for particle reconstitution in vitro has been the manipulation of 'open cores' to become functionally active cores again. The experiments described here were undertaken with the aim of exploring packaging of RV RNAs into opened cores in vitro. Rotavirus cores were opened by approximately 200μM EGTA, leading to the release of genomic dsRNA. Conversely, RV cores were found to be stable in the presence of minimum concentrations of Ca(2+), Mg(2+), spermidine(3+) and cobalthexamine(3+) of between 40 and 300 μM. Aggregates of purified cores were resolved in the presence of 0.3mM deoxycholate (minimum concentration). Core shells opened with EGTA were reconstituted by the addition of di- or trivalent cations within 2 min of the opening procedure. Addition of purified, baculovirus recombinant-expressed VP6 to native and reconstituted cores led to the formation of DLPs or DLP-like particles, which upon transfection into MA104 cells were infectious. The rescued infectivity likely originated in part from unopened and in part from reconstituted cores. Radiolabelled RV (+) ssRNAs could be packaged into reconstituted cores and DLPs, as indicated by resistance to RNase I digestion. The packaging reaction was, however, not RV RNA sequence-specific, since unrelated ssRNAs, such as those transcribed from HIV-2 cDNAs, were also packaged. The kinetics of packaging of homologous and heterologous RNAs were similar, as evidenced by competitive packaging assays. None of the packaged in vitro engineered RNA segments has so far been rescued into infectious virus.
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Affiliation(s)
- Ulrich Desselberger
- Virologie Moléculaire et Structurale, UMR 2472 du CNRS, 1 avenue de la Terrasse, 91198 Gif-sur-Yvette Cédex, France; Molecular Immunology Group, International Centre for Genetic Engineering, Trieste, Italy; Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK.
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Molecular characterization of the porcine group A rotavirus NSP2 and NSP5/6 genes from São Paulo State, Brazil, in 2011/12. ScientificWorldJournal 2013; 2013:241686. [PMID: 23970830 PMCID: PMC3730213 DOI: 10.1155/2013/241686] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 06/29/2013] [Indexed: 11/18/2022] Open
Abstract
Rotaviruses are responsible for the acute diarrhea in various mammalian and avian species. The nonstructural proteins NSP2 and NSP5 are involved in the rotavirus replication and the formation of viroplasm, cytoplasmic inclusion bodies within which new viral particles morphogenesis and viral RNA replication occur. There are few studies on the genetic diversity of those proteins; thus this study aims at characterizing the diversity of rotavirus based on NSP2 and NSP5 genes in rotaviruses circulating in Brazilian pig farms. For this purpose, 63 fecal samples from pig farms located in six different cities in the São Paulo State, Brazil, were screened by nested RT-PCR. Seven strains had the partial nucleotide sequencing for NSP2, whereas in six, the total sequencing for NSP5. All were characterized as genotype H1 and N1. The nucleotide identity of NSP2 genes ranged from 100% to 86.4% and the amino acid identity from 100% to 91.5%. For NSP5, the nucleotide identity was from 100% to 95.1% and the amino acid identity from 100% to 97.4%. It is concluded that the genotypes of the strains circulating in the region of study are in agreement with those reported in the literature for swine and that there is the possibility of interaction between human and animal rotaviruses.
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20
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Development of a stable insect cell line constitutively expressing rotavirus VP2. Virus Res 2013; 172:66-74. [PMID: 23287060 DOI: 10.1016/j.virusres.2012.12.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Revised: 11/22/2012] [Accepted: 12/21/2012] [Indexed: 12/25/2022]
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21
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Martin D, Charpilienne A, Parent A, Boussac A, D'Autreaux B, Poupon J, Poncet D. The rotavirus nonstructural protein NSP5 coordinates a [2Fe‐2S] iron‐sulfur cluster that modulates interaction to RNA. FASEB J 2012. [DOI: 10.1096/fj.12-217182] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Davy Martin
- Virologie Moléculaire et StructuraleUnité Propre de Recherche du Centre National de la Recherche Scientifique (UPR‐CNRS) 3296Unité Sous Contrat de l' Institut National de la Recherche Agronomique (USC‐INRA)Gif sur YvetteFrance
| | - Annie Charpilienne
- Virologie Moléculaire et StructuraleUnité Propre de Recherche du Centre National de la Recherche Scientifique (UPR‐CNRS) 3296Unité Sous Contrat de l' Institut National de la Recherche Agronomique (USC‐INRA)Gif sur YvetteFrance
| | - Aubérie Parent
- Institut de Chimie des Substances NaturellesUPR‐CNRS 2301Centre de Recherche de GifCNRSGif sur YvetteFrance
| | - Alain Boussac
- Institut de Biologie et de Technologies de Saclay (iBiTec‐S)Service de Bioénergétique, Biologie Structurale et Mécanismes (SB2SM)Unité Mixte de Recherche (UMR‐CNRS) 8221Commissariat à l'Énergie Atomique et aux Énergies Alternatives (CEA)‐SaclayGif sur YvetteFrance
| | - Benoit D'Autreaux
- Institut de Chimie des Substances NaturellesUPR‐CNRS 2301Centre de Recherche de GifCNRSGif sur YvetteFrance
| | - Joël Poupon
- Laboratoire de Toxicologie BiologiqueAssistance Publique–Hôpitaux de Paris (AP‐HP), Hôpital LariboisièreParisFrance
| | - Didier Poncet
- Virologie Moléculaire et StructuraleUnité Propre de Recherche du Centre National de la Recherche Scientifique (UPR‐CNRS) 3296Unité Sous Contrat de l' Institut National de la Recherche Agronomique (USC‐INRA)Gif sur YvetteFrance
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Eichwald C, Arnoldi F, Laimbacher AS, Schraner EM, Fraefel C, Wild P, Burrone OR, Ackermann M. Rotavirus viroplasm fusion and perinuclear localization are dynamic processes requiring stabilized microtubules. PLoS One 2012; 7:e47947. [PMID: 23110139 PMCID: PMC3479128 DOI: 10.1371/journal.pone.0047947] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 09/17/2012] [Indexed: 12/21/2022] Open
Abstract
Rotavirus viroplasms are cytosolic, electron-dense inclusions corresponding to the viral machinery of replication responsible for viral template transcription, dsRNA genome segments replication and assembly of new viral cores. We have previously observed that, over time, those viroplasms increase in size and decrease in number. Therefore, we hypothesized that this process was dependent on the cellular microtubular network and its associated dynamic components. Here, we present evidence demonstrating that viroplasms are dynamic structures, which, in the course of an ongoing infection, move towards the perinuclear region of the cell, where they fuse among each other, thereby gaining considerably in size and, simultaneouly, explaining the decrease in numbers. On the viral side, this process seems to depend on VP2 for movement and on NSP2 for fusion. On the cellular side, both the temporal transition and the maintenance of the viroplasms are dependent on the microtubular network, its stabilization by acetylation, and, surprisingly, on a kinesin motor of the kinesin-5 family, Eg5. Thus, we provide for the first time deeper insights into the dynamics of rotavirus replication, which can explain the behavior of viroplasms in the infected cell.
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23
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Hu L, Crawford SE, Hyser JM, Estes MK, Prasad BVV. Rotavirus non-structural proteins: structure and function. Curr Opin Virol 2012; 2:380-8. [PMID: 22789743 DOI: 10.1016/j.coviro.2012.06.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Revised: 06/13/2012] [Accepted: 06/13/2012] [Indexed: 10/28/2022]
Abstract
The replication of rotavirus is a complex process that is orchestrated by an exquisite interplay between the rotavirus non-structural and structural proteins. Subsequent to particle entry and genome transcription, the non-structural proteins coordinate and regulate viral mRNA translation and the formation of electron-dense viroplasms that serve as exclusive compartments for genome replication, genome encapsidation and capsid assembly. In addition, non-structural proteins are involved in antagonizing the antiviral host response and in subverting important cellular processes to enable successful virus replication. Although far from complete, new structural studies, together with functional studies, provide substantial insight into how the non-structural proteins coordinate rotavirus replication. This brief review highlights our current knowledge of the structure-function relationships of the rotavirus non-structural proteins, as well as fascinating questions that remain to be understood.
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Affiliation(s)
- Liya Hu
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, United States
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24
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Suzuki T, Soma J, Kuga K, Miyazaki A, Tsunemitsu H. Sequence and phylogenetic analyses of nonstructural protein 2 genes of species B porcine rotaviruses detected in Japan during 2001–2009. Virus Res 2012; 165:46-51. [DOI: 10.1016/j.virusres.2012.01.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Revised: 12/20/2011] [Accepted: 01/01/2012] [Indexed: 01/10/2023]
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25
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Structural insights into the coupling of virion assembly and rotavirus replication. Nat Rev Microbiol 2012; 10:165-77. [PMID: 22266782 DOI: 10.1038/nrmicro2673] [Citation(s) in RCA: 148] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Viral replication is rapid and robust, but it is far from a chaotic process. Instead, successful production of infectious progeny requires that events occur in the correct place and at the correct time. Rotaviruses (segmented double-stranded RNA viruses of the Reoviridae family) seem to govern their replication through ordered disassembly and assembly of a triple-layered icosahedral capsid. In recent years, high-resolution structural data have provided unprecedented insight into these events. In this Review, we explore the current understanding of rotavirus replication and how it compares to replication of other Reoviridae family members.
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Assembly of Large Icosahedral Double-Stranded RNA Viruses. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 726:379-402. [DOI: 10.1007/978-1-4614-0980-9_17] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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27
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Martin D, Ouldali M, Ménétrey J, Poncet D. Structural organisation of the rotavirus nonstructural protein NSP5. J Mol Biol 2011; 413:209-21. [PMID: 21864538 DOI: 10.1016/j.jmb.2011.08.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Revised: 08/01/2011] [Accepted: 08/04/2011] [Indexed: 10/17/2022]
Abstract
Rotavirus is one of the leading agents of gastroenteritis worldwide. During infection, viral factories (viroplasms) are formed. The rotavirus nonstructural proteins NSP5 and NSP2 are the major building blocks of viroplasms; however, NSP5 function and organisation remain elusive. In this report, we present a structural characterisation of NSP5. Multi-angle laser light scattering, sedimentation velocity and equilibrium sedimentation experiments demonstrate that recombinant full-length NSP5 forms a decamer in solution. Far-Western, pull-down and multi-angle laser light scattering experiments show that NSP5 has two oligomerisation regions. The first region, residues 103-146, is involved in NSP5 dimerisation, whereas the second region, residues 189-198, is responsible for NSP5 decamerisation. Circular dichroism analyses of full-length and truncated forms of NSP5 reveal that the decamerisation region is helical, whereas the dimerisation region involves β-sheets. From these circular dichroism experiments, we also show that the NSP5 protomers contain two α-helices, a disordered N-terminal half and a C-terminal half that is primarily composed of β-sheet folds. This extensive structural characterisation of NSP5 led us to propose a model for its quaternary organisation. Finally, co-expression of NSP5 fragments and NSP2 in uninfected cells shows that the NSP5 decamerisation region is required for viroplasm-like structure formation. However, in vitro, the NSP5 decamerisation region partially inhibits the NSP2-NSP5 interaction. Our NSP5 model suggests that steric hindrance prevents NSP2 from binding to all NSP5 protomers. Some protomers may thus be free to interact with other NSP5 binding partners, such as viral RNAs and the viral polymerase VP1, to perform functions other than viroplasm organisation.
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Affiliation(s)
- Davy Martin
- Virologie Moléculaire et Structurale, UPR-CNRS 3296, USC INRA, Centre de Recherche de Gif, CNRS, 91198 Gif sur Yvette, France.
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28
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Donker NC, Foley M, Tamvakis DC, Bishop R, Kirkwood CD. Identification of an antibody-binding epitope on the rotavirus A non-structural protein NSP2 using phage display analysis. J Gen Virol 2011; 92:2374-2382. [PMID: 21697352 DOI: 10.1099/vir.0.032599-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The non-structural protein 2 (NSP2) of rotavirus has important roles in rotavirus replication associated with RNA binding, hydrolysis of NTPs and RNA, and helix destabilizing properties. A cell-culture assay using an NSP2-specific mAb and polyclonal antiserum to block virus replication showed a 73 and 96 % reduction in the amount of virus produced during replication, respectively. Phage display technology was used to identify the antibody-binding region on the NSP2 protein with the motif (244)T-(Y/F)-Ø-Ø-Ø-X-K-Ø-G(252), where Ø is a hydrophilic residue and X is any amino acid. This region was mapped to the three-dimensional NSP2 crystal structure to visualize the epitope. Analysis revealed identity to a region on NSP2 that mapped to a site exposed on the surface of the protein, which could possibly interfere with a functionally important region of the protein. Antibody binding to this region could disrupt the essential roles of NSP2, such as the formation of viroplasms with NSP5 or the interaction with viral RNA, thereby indicating a possible mechanism for the observed inhibition of virus replication. Genetic analysis of the putative binding region of NSP2 revealed a high level of conservation, suggesting that the region is under strict control.
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Affiliation(s)
- Nicole C Donker
- Department of Microbiology, La Trobe University, Bundoora, Victoria 3083, Australia
- Enteric Virus Group, Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Victoria 3052, Australia
| | - Michael Foley
- Department of Biochemistry, La Trobe University, Bundoora, Victoria 3083, Australia
| | - Debra C Tamvakis
- Department of Biochemistry, La Trobe University, Bundoora, Victoria 3083, Australia
| | - Ruth Bishop
- Enteric Virus Group, Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Victoria 3052, Australia
| | - Carl D Kirkwood
- Department of Microbiology, La Trobe University, Bundoora, Victoria 3083, Australia
- Enteric Virus Group, Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Victoria 3052, Australia
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29
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McDonald SM, Patton JT. Assortment and packaging of the segmented rotavirus genome. Trends Microbiol 2011; 19:136-44. [PMID: 21195621 PMCID: PMC3072067 DOI: 10.1016/j.tim.2010.12.002] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Revised: 11/19/2010] [Accepted: 12/01/2010] [Indexed: 12/13/2022]
Abstract
The rotavirus (RV) genome comprises 11 segments of double-stranded RNA (dsRNA) and is contained within a non-enveloped, icosahedral particle. During assembly, a highly coordinated selective packaging mechanism ensures that progeny RV virions contain one of each genome segment. Cis-acting signals thought to mediate assortment and packaging are associated with putative panhandle structures formed by base-pairing of the ends of RV plus-strand RNAs (+RNAs). Viral polymerases within assembling core particles convert the 11 distinct +RNAs to dsRNA genome segments. It remains unclear whether RV +RNAs are assorted before or during encapsidation, and the functions of viral proteins during these processes are not resolved. However, as reviewed here, recent insights gained from the study of RV and two other segmented RNA viruses, influenza A virus and bacteriophage Φ6, reveal potential mechanisms of RV assortment and packaging.
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Affiliation(s)
- Sarah M McDonald
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-8026, USA
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Abstract
The innermost VP2 core shell of the triple-layered, icosahedral rotavirus particle surrounds the viral genome and RNA processing enzymes, including the RNA-dependent RNA polymerase (VP1). In addition to anchoring VP1 within the core, VP2 is also an essential cofactor that triggers the polymerase to initiate double-stranded RNA (dsRNA) synthesis using packaged plus-strand RNA templates. The VP2 requirement effectively couples packaging with genome replication and ensures that VP1 makes dsRNA only within an assembling previrion particle. However, the mechanism by which the rotavirus core shell protein activates the viral polymerase remains very poorly understood. In the current study, we sought to elucidate VP2 regions critical for VP1-mediated in vitro dsRNA synthesis. By comparing the functions of proteins from several different rotaviruses, we found that polymerase activation by the core shell protein is specific. Through truncation and chimera mutagenesis, we demonstrate that the VP2 amino terminus, which forms a decameric, internal hub underneath each 5-fold axis, plays an important but nonspecific role in VP1 activation. Our results indicate that the VP2 residues correlating with polymerase activation specificity are located on the inner face of the core shell, distinct from the amino terminus. Based on these findings, we predict that several regions of VP2 engage the polymerase during the concerted processes of rotavirus core assembly and genome replication.
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Contin R, Arnoldi F, Campagna M, Burrone OR. Rotavirus NSP5 orchestrates recruitment of viroplasmic proteins. J Gen Virol 2010; 91:1782-93. [PMID: 20200190 DOI: 10.1099/vir.0.019133-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Rotavirus genome replication and the first steps of virus morphogenesis take place in cytoplasmic viral factories, called viroplasms, containing four structural (VP1, VP2, VP3 and VP6) and two non-structural (NSP2 and NSP5) proteins. NSP2 and NSP5 have been shown to be essential for viroplasm formation and, when co-expressed in uninfected cells, to form viroplasm-like structures (VLS). In the present work, VLS formation was shown upon co-expression of NSP5 with the core protein VP2 despite the absence of NSP2, indicating a central role for NSP5 in VLS assembly. Since VP2 and NSP2 also induce NSP5 hyperphosphorylation, the possible correlation between VLS formation and the NSP5 phosphorylation status was investigated without evidence of a direct link. In VLS induced by NSP2, the polymerase VP1 was recruited, while the middle layer protein VP6 was not, forming instead tubular structures. On the other hand, VLS induced by VP2 were able to recruit both VP1 and VP6. More importantly, in VLS formed when NSP5 was expressed with both inducers, all viroplasmic proteins were found co-localized, resembling their distribution in viroplasms. Our results suggest a key role for NSP5 in architectural assembly of viroplasms and in recruitment of viroplasmic proteins. A new role for VP2 as an inducer of viroplasms and of NSP5 hyperphosphorylation is also described. These data may contribute to the understanding of rotavirus morphogenesis.
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Affiliation(s)
- R Contin
- International Centre for Genetic Engineering and Biotechnology (ICGEB), Padriciano 99, 34149 Trieste, Italy
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Clark KB, Lin SC, Humphrey C, Foytich K, Esona M, Wang Y, Liu M, Jiang B. Expression and characterization of human group C rotavirus virus-like particles in insect cells. Virology 2009; 387:267-72. [DOI: 10.1016/j.virol.2009.02.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Revised: 02/09/2009] [Accepted: 02/17/2009] [Indexed: 11/30/2022]
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Abstract
Studies on the molecular biology of rotavirus, the major etiologic agent of gastroenteritis in infants and young children worldwide, have so far led to a large but not exhaustive knowledge of the mechanisms by which rotavirus replicates in the host cell. While the role of rotavirus structural proteins in the replication cycle is well defined, the functions of nonstructural proteins remain poorly understood. Recent experiments of RNA interference have clearly indicated the phases of the replication cycle for which the nonstructural proteins are essentially required. In addition, biochemical studies of their interactions with other viral proteins, together with immunofluorescence experiments on cells expressing recombinant proteins in different combinations, are providing new indications of their functions. This article contains a critical collection of the most recent achievements and the current hypotheses about the roles of nonstructural proteins in virus replication.
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Affiliation(s)
- Francesca Arnoldi
- International Centre for Genetic Engineering & Biotechnology (ICGEB), Padriciano 99, 34012 Trieste, Italy
| | - Oscar R Burrone
- International Centre for Genetic Engineering & Biotechnology (ICGEB), Padriciano 99, 34012 Trieste, Italy
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Campagna M, Budini M, Arnoldi F, Desselberger U, Allende JE, Burrone OR. Impaired hyperphosphorylation of rotavirus NSP5 in cells depleted of casein kinase 1alpha is associated with the formation of viroplasms with altered morphology and a moderate decrease in virus replication. J Gen Virol 2007; 88:2800-2810. [PMID: 17872534 DOI: 10.1099/vir.0.82922-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The rotavirus (RV) non-structural protein 5, NSP5, is encoded by the smallest of the 11 genomic segments and localizes in 'viroplasms', cytoplasmic inclusion bodies in which viral RNA replication and packaging take place. NSP5 is essential for the replicative cycle of the virus because, in its absence, viroplasms are not formed and viral RNA replication and transcription do not occur. NSP5 is produced early in infection and undergoes a complex hyperphosphorylation process, leading to the formation of proteins differing in electrophoretic mobility. The role of hyperphosphorylation of NSP5 in the replicative cycle of rotavirus is unknown. Previous in vitro studies have suggested that the cellular kinase CK1alpha is responsible for the NSP5 hyperphosphorylation process. Here it is shown, by means of specific RNA interference, that in vivo, CK1alpha is the enzyme that initiates phosphorylation of NSP5. Lack of NSP5 hyperphosphorylation affected neither its interaction with the virus VP1 and NSP2 proteins normally found in viroplasms, nor the production of viral proteins. In contrast, the morphology of viroplasms was altered markedly in cells in which CK1alpha was depleted and a moderate decrease in the production of double-stranded RNA and infectious virus was observed. These data show that CK1alpha is the kinase that phosphorylates NSP5 in virus-infected cells and contribute to further understanding of the role of NSP5 in RV infection.
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Affiliation(s)
- Michela Campagna
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34011 Trieste, Italy
| | - Mauricio Budini
- Instituto de Ciencias Biomedicas, Programa de Biologia Celular y Molecular, Facultad de Medicina, Universidad de Chile, Independencia 1027, 8380453 Santiago, Chile
| | - Francesca Arnoldi
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34011 Trieste, Italy
| | - Ulrich Desselberger
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34011 Trieste, Italy
| | - Jorge E Allende
- Instituto de Ciencias Biomedicas, Programa de Biologia Celular y Molecular, Facultad de Medicina, Universidad de Chile, Independencia 1027, 8380453 Santiago, Chile
| | - Oscar R Burrone
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34011 Trieste, Italy
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Bar-Magen T, Spencer E, Patton JT. An ATPase activity associated with the rotavirus phosphoprotein NSP5. Virology 2007; 369:389-99. [PMID: 17825341 PMCID: PMC2702534 DOI: 10.1016/j.virol.2007.07.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2007] [Revised: 07/04/2007] [Accepted: 07/25/2007] [Indexed: 02/02/2023]
Abstract
Interactions between NSP5 and NSP2 drive the formation of viroplasms, sites of genome replication and packaging in rotavirus-infected cells. The serine-threonine-rich NSP5 transitions between hypo- and hyper-phosphorylated isomers during the replication cycle. In this study, we determined that purified recombinant NSP5 has a Mg2+-dependent ATP-specific triphosphatase activity that generates free ADP and Pi (Vmax of 19.33 fmol of product/min/pmol of enzyme). The ATPase activity was correlated with low levels of NSP5 phosphorylation, suggestive of a possible link between ATP hydrolysis and an NSP5 autokinase activity. Mutagenesis showed that the critical residue (Ser67) needed for NSP5 hyperphosphorylation by cellular casein kinase-like enzymes has no role in the ATPase or autokinase activities of NSP5. Through its NDP kinase activity, the NSP2 octamer may support NSP5 phosphorylation by creating a constant source of ATP molecules for the autokinase activity of NSP5 and for cellular kinases associated with NSP5.
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Affiliation(s)
- Tamara Bar-Magen
- Laboratorio de Virologia, Facultad de Quimica y Biologia, Universidad de Santiago, Santauthor: Laboratory of Infectious Diseases, NIAID, National, Institutes of Health, 50 South Drive, MSC 8026, Room 6314, Bethesda, MD 20892-8026, USA, Phone: (301) 594-1615, Fax: (301) 496-8312,
| | - Eugenio Spencer
- Laboratorio de Virologia, Facultad de Quimica y Biologia, Universidad de Santiago, Santauthor: Laboratory of Infectious Diseases, NIAID, National, Institutes of Health, 50 South Drive, MSC 8026, Room 6314, Bethesda, MD 20892-8026, USA, Phone: (301) 594-1615, Fax: (301) 496-8312,
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Cabral-Romero C, Padilla-Noriega L. Association of rotavirus viroplasms with microtubules through NSP2 and NSP5. Mem Inst Oswaldo Cruz 2007; 101:603-11. [PMID: 17072471 DOI: 10.1590/s0074-02762006000600006] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2006] [Accepted: 04/10/2006] [Indexed: 11/22/2022] Open
Abstract
Rotavirus replication and virus assembly take place in electrodense spherical structures known as viroplasms whose main components are the viral proteins NSP2 and NSP5. The viroplasms are produced since early times after infection and seem to grow by stepwise addition of viral proteins and by fusion, however, the mechanism of viropIasms formation is unknown. In this study we found that the viroplasms surface colocalized with microtubules, and seem to be caged by a microtubule network. Moreover inhibition of microtubule assembly with nocodazole interfered with viroplasms growth in rotavirus infected cells. We searched for a physical link between viroplasms and microtubules by co-immunoprecipitation assays, and we found that the proteins NSP2 and NSP5 were co-immunoprecipitated with anti-tubulin in rotavirus infected cells and also when they were transiently co-expressed or individually expressed. These results indicate that a functional microtubule network is needed for viroplasm growth presumably due to the association of viroplasms with microtubules via NSP2 and NSP5.
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Affiliation(s)
- Claudio Cabral-Romero
- Departamento de Biología Molecular, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, DF 04510, México
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37
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Arnoldi F, Campagna M, Eichwald C, Desselberger U, Burrone OR. Interaction of rotavirus polymerase VP1 with nonstructural protein NSP5 is stronger than that with NSP2. J Virol 2007; 81:2128-37. [PMID: 17182692 PMCID: PMC1865955 DOI: 10.1128/jvi.01494-06] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Accepted: 12/07/2006] [Indexed: 01/19/2023] Open
Abstract
Rotavirus morphogenesis starts in intracellular inclusion bodies called viroplasms. RNA replication and packaging are mediated by several viral proteins, of which VP1, the RNA-dependent RNA polymerase, and VP2, the core scaffolding protein, were shown to be sufficient to provide replicase activity in vitro. In vivo, however, viral replication complexes also contain the nonstructural proteins NSP2 and NSP5, which were shown to be essential for replication, to interact with each other, and to form viroplasm-like structures (VLS) when coexpressed in uninfected cells. In order to gain a better understanding of the intermediates formed during viral replication, this work focused on the interactions of NSP5 with VP1, VP2, and NSP2. We demonstrated a strong interaction of VP1 with NSP5 but only a weak one with NSP2 in cotransfected cells in the absence of other viral proteins or viral RNA. By contrast, we failed to coimmunoprecipitate VP2 with anti-NSP5 antibodies or NSP5 with anti-VP2 antibodies. We constructed a tagged form of VP1, which was found to colocalize in viroplasms and in VLS formed by NSP5 and NSP2. The tagged VP1 was able to replace VP1 structurally by being incorporated into progeny viral particles. When applying anti-tag-VP1 or anti-NSP5 antibodies, coimmunoprecipitation of tagged VP1 with NSP5 was found. Using deletion mutants of NSP5 or different fragments of NSP5 fused to enhanced green fluorescent protein, we identified the 48 C-terminal amino acids as the region essential for interaction with VP1.
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Affiliation(s)
- F Arnoldi
- International Centre for Genetic Engineering and Biotechnology (ICGEB), Padriciano 99, 34012 Trieste, Italy
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38
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Pesavento JB, Crawford SE, Estes MK, Prasad BVV. Rotavirus proteins: structure and assembly. Curr Top Microbiol Immunol 2006; 309:189-219. [PMID: 16913048 DOI: 10.1007/3-540-30773-7_7] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Rotavirus is a major pathogen of infantile gastroenteritis. It is a large and complex virus with a multilayered capsid organization that integrates the determinants of host specificity, cell entry, and the enzymatic functions necessary for endogenous transcription of the genome that consists of 11 dsRNA segments. These segments encode six structural and six nonstructural proteins. In the last few years, there has been substantial progress in our understanding of both the structural and functional aspects of a variety of molecular processes involved in the replication of this virus. Studies leading to this progress using of a variety of structural and biochemical techniques including the recent application of RNA interference technology have uncovered several unique and intriguing features related to viral morphogenesis. This review focuses on our current understanding of the structural basis of the molecular processes that govern the replication of rotavirus.
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Affiliation(s)
- J B Pesavento
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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39
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Patton JT, Silvestri LS, Tortorici MA, Vasquez-Del Carpio R, Taraporewala ZF. Rotavirus genome replication and morphogenesis: role of the viroplasm. Curr Top Microbiol Immunol 2006; 309:169-87. [PMID: 16909900 DOI: 10.1007/3-540-30773-7_6] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The rotaviruses, members of the family Reoviridae, are icosahedral triple-layered viruses with genomes consisting of 11 segments of double-stranded (ds)RNA. A characteristic feature of rotavirus-infected cells is the formation of large cytoplasmic inclusion bodies, termed viroplasms. These dynamic and highly organized structures serve as viral factories that direct the packaging and replication of the viral genome into early capsid assembly intermediates. Migration of the intermediates to the endoplasmic reticulum (ER) initiates a budding process that culminates in final capsid assembly. Recent information on the development and organization of viroplasms, the structure and function of its components, and interactive pathways linking RNA synthesis and capsid assembly provide new insight into how these microenvironments serve to interface the replication and morphogenetic processes of the virus.
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Affiliation(s)
- J T Patton
- Laboratory of Infectious Diseases, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, 50 South Drive, MSC 8026, Room 6314, Bethesda, MD 20892-8026, USA.
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Jiang X, Jayaram H, Kumar M, Ludtke SJ, Estes MK, Prasad BVV. Cryoelectron microscopy structures of rotavirus NSP2-NSP5 and NSP2-RNA complexes: implications for genome replication. J Virol 2006; 80:10829-35. [PMID: 16928740 PMCID: PMC1641785 DOI: 10.1128/jvi.01347-06] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The replication and packaging of the rotavirus genome, comprising 11 segments of double-stranded RNA, take place in specialized compartments called viroplasms, which are formed during infection and involve a coordinated interplay of multiple components. Two rotavirus nonstructural proteins, NSP2 (with nucleoside triphosphatase, single-stranded RNA [ssRNA] binding and helix-destabilizing activities) and NSP5, are essential in these events. Previous structural analysis of NSP2 showed that it is an octamer in crystals, obeying 4-2-2 crystal symmetry, with a large 35-A central hole along the fourfold axis and deep grooves at one of the twofold axes. To ascertain that the solution structure of NSP2 is the same as that in the crystals and investigate how NSP2 interacts with NSP5 and RNA, we carried out single-particle cryoelectron microscopy (cryo-EM) analysis of NSP2 alone and in complexes with NSP5 and ssRNA at subnanometer resolution. Because full-length NSP5 caused severe aggregation upon mixing with NSP2, the deletion construct NSP566-188 was used in these studies. Our studies show that the solution structure of NSP2 is same as the crystallographic octamer and that both NSP566-188 and ssRNA bind to the grooves in the octamer, which are lined by positively charged residues. The fitting of the NSP2 crystal structure to cryo-EM reconstructions of the complexes indicates that, in contrast to the binding of NSP566-188, the binding of RNA induces noticeable conformational changes in the NSP2 octamer. Consistent with the observation that both NSP5 and RNA share the same binding site on the NSP2 octamer, filter binding assays showed that NSP5 competes with ssRNA binding, indicating that one of the functions of NSP5 is to regulate NSP2-RNA interactions during genome replication.
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Affiliation(s)
- Xiaofang Jiang
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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41
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Mena JA, Ramírez OT, Palomares LA. Intracellular distribution of rotavirus structural proteins and virus-like particles expressed in the insect cell-baculovirus system. J Biotechnol 2006; 122:443-52. [PMID: 16290307 DOI: 10.1016/j.jbiotec.2005.10.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2005] [Revised: 09/15/2005] [Accepted: 10/06/2005] [Indexed: 11/24/2022]
Abstract
The production of virus-like particles (VLP) is of interest to several fields. However, little is known about their assembly when they are expressed in insect cells, as it occurs in conditions different to those of native virus. Knowledge of the localization of recombinant proteins and of the site of accumulation of VLP can increase the understanding of VLP assembly and be useful for proposing production strategies. In this work, the rotavirus proteins VP6 and the fusion protein GFPVP2 were expressed in High Five insect cells. Recombinant proteins and rotavirus-like particles (RLP) were located and visualized by confocal, epifluorescence and electron microscopy. Single-layered (sl) RLP (conformed by GFPVP2) accumulated in the cytoplasm as highly ordered aggregates. In contrast, VP6 formed fibrillar structures composed of various tubes of VP6 that were not associated to microtubules. Coexpression of GFPVP2 and VP6 altered the distribution of both proteins. VP6 formed aggregates, even when all other conditions of individual protein expression remained unchanged. Double-layered (dl) RLP were observed in dense zones of the cytoplasm, but were not in ordered aggregates. It was determined that the assembly of both slRLP and dlRLP occurs intracellularly. Accordingly, strategies for the optimum assembly of dlRLP should guarantee that each cell produces both recombinant proteins.
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Affiliation(s)
- Jimmy A Mena
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, Morelos CP 62250, Mexico
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Wei T, Shimizu T, Hagiwara K, Kikuchi A, Moriyasu Y, Suzuki N, Chen H, Omura T. Pns12 protein of Rice dwarf virus is essential for formation of viroplasms and nucleation of viral-assembly complexes. J Gen Virol 2006; 87:429-438. [PMID: 16432031 DOI: 10.1099/vir.0.81425-0] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cytoplasmic inclusion bodies, known as viroplasms or viral factories, are assumed to be the sites of replication of members of the family Reoviridae. Immunocytochemical and biochemical analyses were carried out to characterize the poorly understood viroplasms of the phytoreovirus Rice dwarf virus (RDV). Within 6 h of inoculation of cells, viroplasms, namely discrete cytoplasmic inclusions, were formed that contained the non-structural proteins Pns6, Pns11 and Pns12 of RDV, which appeared to be the constituents of the inclusions. Formation of similar inclusions in non-host insect cells upon expression of Pns12 in a baculovirus system and the association of molecules of Pns12 in vitro suggested that the inclusions observed in RDV-infected cells were composed basically of Pns12. Core proteins P1, P3, P5 and P7 and core virus particles were identified in the interior region of the inclusions. In contrast, accumulation of the outer capsid proteins P2, P8 and P9 and of intact virus particles was evident in the peripheral regions of the inclusions. These observations suggest that core particles were constructed inside the inclusions, whereas outer capsid proteins were assembled at the periphery of the inclusions. Viral inclusions were shown to be the sites of viral RNA synthesis by labelling infected cells with 5-bromouridine 5'-triphosphate. The number of viroplasms decreased with time post-inoculation as their sizes increased, suggesting that inclusions might fuse with one another during the virus-propagation process. Our results are consistent with a model, proposed for vertebrate reoviruses, in which viroplasms play a pivotal role in virus assembly.
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Affiliation(s)
- Taiyun Wei
- Laboratory of Virology, National Agricultural Research Center, 3-1-1 Kannondai, Tsukuba, Ibaraki 305-8666, Japan
| | - Takumi Shimizu
- Laboratory of Virology, National Agricultural Research Center, 3-1-1 Kannondai, Tsukuba, Ibaraki 305-8666, Japan
| | - Kyoji Hagiwara
- Laboratory of Virology, National Agricultural Research Center, 3-1-1 Kannondai, Tsukuba, Ibaraki 305-8666, Japan
| | - Akira Kikuchi
- Laboratory of Virology, National Agricultural Research Center, 3-1-1 Kannondai, Tsukuba, Ibaraki 305-8666, Japan
| | - Yusuke Moriyasu
- Faculty of Agriculture, Ibaraki University, Ami, Ibaraki 300-0332, Japan
- Laboratory of Virology, National Agricultural Research Center, 3-1-1 Kannondai, Tsukuba, Ibaraki 305-8666, Japan
| | - Nobuhiro Suzuki
- Research Institute for Bioresources, Okayama University, 2-20-1 Chuo, Kurashiki, Okayama 710-0046, Japan
| | - Hongyan Chen
- Laboratory of Virology, National Agricultural Research Center, 3-1-1 Kannondai, Tsukuba, Ibaraki 305-8666, Japan
| | - Toshihiro Omura
- Laboratory of Virology, National Agricultural Research Center, 3-1-1 Kannondai, Tsukuba, Ibaraki 305-8666, Japan
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Sen A, Agresti D, Mackow ER. Hyperphosphorylation of the rotavirus NSP5 protein is independent of serine 67, [corrected] NSP2, or [corrected] the intrinsic insolubility of NSP5 is regulated by cellular phosphatases. J Virol 2006; 80:1807-16. [PMID: 16439537 PMCID: PMC1367154 DOI: 10.1128/jvi.80.4.1807-1816.2006] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The NSP5 protein is required for viroplasm formation during rotavirus infection and is hyperphosphorylated into 32- to 35-kDa isoforms. Earlier studies reported that NSP5 is not hyperphosphorylated without NSP2 coexpression or deleting the NSP5 N terminus and that serine 67 is essential for NSP5 hyperphosphorylation. In this report, we show that full-length NSP5 is hyperphosphorylated in the absence of NSP2 or serine 67 and demonstrate that hyperphosphorylated NSP5 is predominantly present in previously unrecognized cellular fractions that are insoluble in 0.2% sodium dodecyl sulfate. The last 68 residues of NSP5 are sufficient to direct green fluorescent protein into insoluble fractions and cause green fluorescent protein localization into viroplasm-like structures; however, NSP5 insolubility was intrinsic and did not require NSP5 hyperphosphorylation. When we mutated serine 67 to alanine we found that the NSP5 mutant was both hyperphosphorylated and insoluble, identical to unmodified NSP5, and as a result serine 67 is not required for NSP5 phosphorylation. Interestingly, treating cells with the phosphatase inhibitor calyculin A permitted the accumulation of soluble hyperphosphorylated NSP5 isoforms. This suggests that soluble NSP5 is constitutively dephosphorylated by cellular phosphatases and demonstrates that hyperphosphorylation does not direct NSP5 insolubility. Collectively these findings indicate that NSP5 hyperphosphorylation and insolubility are completely independent parameters and that analyzing insoluble NSP5 is essential for studies assessing NSP5 phosphorylation. Our results also demonstrate the involvement of cellular phosphatases in regulating NSP5 phosphorylation and indicate that in the absence of other rotavirus proteins, domains on soluble and insoluble NSP5 recruit cellular kinases and phosphatases that coordinate NSP5 hyperphosphorylation.
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Affiliation(s)
- Adrish Sen
- Department of Medicine and Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11794, USA
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Patton JT, Vasquez-Del Carpio R, Tortorici MA, Taraporewala ZF. Coupling of Rotavirus Genome Replication and Capsid Assembly. Adv Virus Res 2006; 69:167-201. [PMID: 17222694 DOI: 10.1016/s0065-3527(06)69004-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The Reoviridae family represents a diverse collection of viruses with segmented double-stranded (ds)RNA genomes, including some that are significant causes of disease in humans, livestock, and plants. The genome segments of these viruses are never detected free in the infected cell but are transcribed and replicated within viral cores by RNA-dependent RNA polymerase (RdRP). Insight into the replication mechanism has been provided from studies on Rotavirus, a member of the Reoviridae whose RdRP can specifically recognize viral plus (+) strand RNAs and catalyze their replication to dsRNAs in vitro. These analyses have revealed that although the rotavirus RdRP can interact with recognition signals in (+) strand RNAs in the absence of other proteins, the conversion of this complex to one that can support initiation of dsRNA synthesis requires the presence and partial assembly of the core capsid protein. By this mechanism, the viral polymerase can carry out dsRNA synthesis only when capsid protein is available to package its newly made product. By preventing the accumulation of naked dsRNA within the cell, the virus avoids triggering dsRNA-dependent interferon signaling pathways that can induce expression and activation of antiviral host proteins.
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Affiliation(s)
- John T Patton
- Laboratory of Infectious Diseases, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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45
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Vascotto F, Visintin M, Cattaneo A, Burrone OR. Design and selection of an intrabody library produced de-novo for the non-structural protein NSP5 of rotavirus. J Immunol Methods 2005; 301:31-40. [PMID: 15907924 DOI: 10.1016/j.jim.2005.03.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2004] [Revised: 02/24/2005] [Accepted: 03/10/2005] [Indexed: 11/22/2022]
Abstract
Intracellular antibodies or intrabodies have great potential in protein knockout strategies for intracellular antigens. We applied the Intracellular Antibody Capture Technology for the direct selection in yeast of a mouse scFv library (V(L)-V(H) format) constructed from animals immunised with recombinant non-structural protein NSP5 of Rotavirus. We selected five different intracellular antibodies (ICAbs), which specifically recognize Delta2, an NSP5 deletion mutant used as bait. The anti-NSP5 ICAbs were well expressed both in yeast and mammalian cells as cytoplasmic or nuclear-tagged forms. By immunofluorescence and co-immunoprecipitation assays we characterised the intracellular interaction of the five anti-NSP5 ICAbs with the co-expressed antigens.
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Affiliation(s)
- Fulvia Vascotto
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34012 Trieste, Italy
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46
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López T, Rojas M, Ayala-Bretón C, López S, Arias CF. Reduced expression of the rotavirus NSP5 gene has a pleiotropic effect on virus replication. J Gen Virol 2005; 86:1609-1617. [PMID: 15914838 DOI: 10.1099/vir.0.80827-0] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Rotavirus RRV gene 11 encodes two non-structural proteins, NSP5 and NSP6. NSP5 is a phosphorylated non-structural protein that binds single- and double-stranded RNA in a non-specific manner. Transient expression of this protein in uninfected cells has provided evidence for its participation in the formation of electron-dense cytoplasmic structures, known as viroplasms, which are thought to be key structures for the replication of the virus. NSP6 is a protein of unknown function that seems not to be essential for virus replication in cell culture. To study the function of NSP5 in the context of a viral infection, the expression of RRV gene 11 was silenced by RNA interference. Reduction in the synthesis of NSP5, as shown by immunoblot and immunofluorescence assays, correlated with a reduction in the number and size of viroplasms and with an altered intracellular distribution of other viroplasm-associated proteins. Silencing of gene 11 also resulted in a reduced synthesis of viral RNA(+) and double-stranded RNA and of all viral proteins, as well as in a decreased production of infectious virus. A similar phenotype was observed when the NSP5 coding gene of the lapine rotavirus strain Alabama was silenced. The fact that the NSP5 gene of rotavirus Alabama lacks the AUG initiator codon for a complete NSP6 protein, suggests that the described phenotype in gene 11-silenced cells is mostly due to the absence of NSP5. The data presented in this work suggest that NSP5 is a key protein during the replication cycle of rotaviruses.
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Affiliation(s)
- Tomás López
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Col. Chamilpa, Cuernavaca, Morelos 62210, Mexico
| | - Margarito Rojas
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Col. Chamilpa, Cuernavaca, Morelos 62210, Mexico
| | - Camilo Ayala-Bretón
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Col. Chamilpa, Cuernavaca, Morelos 62210, Mexico
| | - Susana López
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Col. Chamilpa, Cuernavaca, Morelos 62210, Mexico
| | - Carlos F Arias
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Col. Chamilpa, Cuernavaca, Morelos 62210, Mexico
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47
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Campagna M, Eichwald C, Vascotto F, Burrone OR. RNA interference of rotavirus segment 11 mRNA reveals the essential role of NSP5 in the virus replicative cycle. J Gen Virol 2005; 86:1481-1487. [PMID: 15831961 DOI: 10.1099/vir.0.80598-0] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Rotavirus genomes contain 11 double-stranded (ds) RNA segments. Genome segment 11 encodes the non-structural protein NSP5 and, in some strains, also NSP6. NSP5 is produced soon after viral infection and localizes in cytoplasmic viroplasms, where virus replication takes place. RNA interference by small interfering (si) RNAs targeted to genome segment 11 mRNA of two different strains blocked production of NSP5 in a strain-specific manner, with a strong effect on the overall replicative cycle: inhibition of viroplasm formation, decreased production of other structural and non-structural proteins, synthesis of viral genomic dsRNA and production of infectious particles. These effects were shown not to be due to inhibition of NSP6. The results obtained strengthen the importance of secondary transcription/translation in rotavirus replication and demonstrate that NSP5 is essential for the assembly of viroplasms and virus replication.
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Affiliation(s)
- Michela Campagna
- International Centre for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, 34012 Trieste, Italy
| | - Catherine Eichwald
- International Centre for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, 34012 Trieste, Italy
| | - Fulvia Vascotto
- International Centre for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, 34012 Trieste, Italy
| | - Oscar R Burrone
- International Centre for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, 34012 Trieste, Italy
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48
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Vascotto F, Campagna M, Visintin M, Cattaneo A, Burrone OR. Effects of intrabodies specific for rotavirus NSP5 during the virus replicative cycle. J Gen Virol 2004; 85:3285-3290. [PMID: 15483242 DOI: 10.1099/vir.0.80075-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Intracellular antibodies or intrabodies (ICAbs) have great potential in protein knockout strategies for intracellular antigens. In this study, they have been used to investigate the role of the rotavirus non-structural protein NSP5 in the virus replication cycle. Intracellular antibody-capture technology was used to select single-chain Fv format (scFv) ICAbs against an NSP5 mutant. Five different specific ICAbs were selected and expressed in MA104 cells, in the scFv format, as cytoplasmic- and nuclear-tagged forms. By confocal microscopy, it was found that three of these ICAbs recognized the full-length wild-type NSP5 specifically, forming antigen-specific aggresomes in the cytoplasm of cotransfected cells. Expression of the ICAbs in rotavirus-infected cells largely reduced the assembly of viroplasms and cellular cytopathic effect. Replication of dsRNA was partially inhibited, despite there being no reduction in virus titre. These results demonstrate for the first time a key role for NSP5 during the virus replicative cycle.
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Affiliation(s)
- Fulvia Vascotto
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34012 Trieste, Italy
| | - Michela Campagna
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34012 Trieste, Italy
| | - Michela Visintin
- Lay Line Genomics SpA, via di Castel Romano 100, 00128 Roma, Italy
| | - Antonino Cattaneo
- Scuola Internazionale Superiore di Studi Avanzati, Ed. B, Padriciano 99, 34012 Trieste, Italy
- Lay Line Genomics SpA, via di Castel Romano 100, 00128 Roma, Italy
| | - Oscar R Burrone
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34012 Trieste, Italy
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Eichwald C, Jacob G, Muszynski B, Allende JE, Burrone OR. Uncoupling substrate and activation functions of rotavirus NSP5: phosphorylation of Ser-67 by casein kinase 1 is essential for hyperphosphorylation. Proc Natl Acad Sci U S A 2004; 101:16304-9. [PMID: 15520389 PMCID: PMC528968 DOI: 10.1073/pnas.0406691101] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Rotavirus NSP5 is a nonstructural protein that localizes in viroplasms of virus-infected cells. NSP5 interacts with NSP2 and undergoes a complex posttranslational hyperphosphorylation, generating species with reduced PAGE mobility. Here we show that NSP5 operates as an autoregulator of its own phosphorylation as a consequence of two distinct activities of the protein: substrate and activator. We developed an in vivo hyperphosphorylation assay in which two NSP5 mutant constructs are cotransfected. One of them, fused to an 11-aa tag, served as substrate whereas the other was used to map NSP5 domains required for activation. The activation and substrate activity could be uncoupled, demonstrating a hyperphosphorylation process in trans between the activator and substratum. This process involved dimerization of the two components through the 18-aa C-terminal tail. Phosphorylation of Ser-67 within the SDSAS motif (amino acids 63-67) was required to trigger hyperphosphorylation by promoting the activation function. We present evidence of casein kinase 1alpha being the protein kinase responsible for this key step as well as for the consecutive ones leading to NSP5 hyperphosphorylation.
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Affiliation(s)
- Catherine Eichwald
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34012 Trieste, Italy
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50
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Eichwald C, Rodriguez JF, Burrone OR. Characterization of rotavirus NSP2/NSP5 interactions and the dynamics of viroplasm formation. J Gen Virol 2004; 85:625-634. [PMID: 14993647 DOI: 10.1099/vir.0.19611-0] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Viroplasms are discrete structures formed in the cytoplasm of rotavirus-infected cells and constitute the replication machinery of the virus. The non-structural proteins NSP2 and NSP5 localize in viroplasms together with other viral proteins, including the polymerase VP1, VP3 and the main inner-core protein, VP2. NSP2 and NSP5 interact with each other, activating NSP5 hyperphosphorylation and the formation of viroplasm-like structures (VLSs). We have used NSP2 and NSP5 fused to the enhanced green fluorescent protein (EGFP) to investigate the localization of both proteins within viroplasms in virus-infected cells, as well as the dynamics of viroplasm formation. The number of viroplasms was shown first to increase and then to decrease with time post-infection, while the area of each one increased, suggesting the occurrence of fusions. The interaction between NSP2 and a series of NSP5 mutants was investigated using two different assays, a yeast two-hybrid system and an in vivo binding/immunoprecipitation assay. Both methods gave comparable results, indicating that the N-terminal region (33 aa) as well as the C-terminal part (aa 131-198) of NSP5 are required for binding to NSP2. When fused to the N and C terminus of EGFP, respectively, these two regions were able to confer the ability to localize in the viroplasm and to form VLSs with NSP2.
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Affiliation(s)
- Catherine Eichwald
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34012 Trieste, Italy
| | - José Francisco Rodriguez
- Department of Biología Molecular y Celular, Centro Nacional de Biotecnología, Cantoblanco, 28049 Madrid, Spain
| | - Oscar R Burrone
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34012 Trieste, Italy
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