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Nichols SL, Haller C, Borodavka A, Esstman SM. Rotavirus NSP2: A Master Orchestrator of Early Viral Particle Assembly. Viruses 2024; 16:814. [PMID: 38932107 PMCID: PMC11209291 DOI: 10.3390/v16060814] [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: 04/18/2024] [Revised: 05/06/2024] [Accepted: 05/16/2024] [Indexed: 06/28/2024] Open
Abstract
Rotaviruses (RVs) are 11-segmented, double-stranded (ds) RNA viruses and important causes of acute gastroenteritis in humans and other animal species. Early RV particle assembly is a multi-step process that includes the assortment, packaging and replication of the 11 genome segments in close connection with capsid morphogenesis. This process occurs inside virally induced, cytosolic, membrane-less organelles called viroplasms. While many viral and cellular proteins play roles during early RV assembly, the octameric nonstructural protein 2 (NSP2) has emerged as a master orchestrator of this key stage of the viral replication cycle. NSP2 is critical for viroplasm biogenesis as well as for the selective RNA-RNA interactions that underpin the assortment of 11 viral genome segments. Moreover, NSP2's associated enzymatic activities might serve to maintain nucleotide pools for use during viral genome replication, a process that is concurrent with early particle assembly. The goal of this review article is to summarize the available data about the structures, functions and interactions of RV NSP2 while also drawing attention to important unanswered questions in the field.
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Affiliation(s)
- Sarah L. Nichols
- Department of Biology, Wake Forest University, Wake Downtown, 455 Vine Street, Winston-Salem, NC 27106, USA;
| | - Cyril Haller
- Department of Chemical Engineering and Biotechnology, Cambridge University, Philippa Fawcett Drive, Cambridge CB3 0AS, UK;
| | - Alexander Borodavka
- Department of Chemical Engineering and Biotechnology, Cambridge University, Philippa Fawcett Drive, Cambridge CB3 0AS, UK;
| | - Sarah M. Esstman
- Department of Biology, Wake Forest University, Wake Downtown, 455 Vine Street, Winston-Salem, NC 27106, USA;
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2
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Chamera S, Wycisk K, Czarnocki-Cieciura M, Nowotny M. Cryo-EM structure of rotavirus B NSP2 reveals its unique tertiary architecture. J Virol 2024; 98:e0166023. [PMID: 38421167 PMCID: PMC10949507 DOI: 10.1128/jvi.01660-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 01/23/2024] [Indexed: 03/02/2024] Open
Abstract
Rotavirus (RV) NSP2 is a multifunctional RNA chaperone that exhibits numerous activities that are essential for replication and viral genome packaging. We performed an in silico analysis that highlighted a distant relationship of NSP2 from rotavirus B (RVB) to proteins from other human RVs. We solved a cryo-electron microscopy structure of RVB NSP2 that shows structural differences with corresponding proteins from other human RVs. Based on the structure, we identified amino acid residues that are involved in RNA interactions. Anisotropy titration experiments showed that these residues are important for nucleic acid binding. We also identified structural motifs that are conserved in all RV species. Collectively, our data complete the structural characterization of rotaviral NSP2 protein and demonstrate its structural diversity among RV species.IMPORTANCERotavirus B (RVB), also known as adult diarrhea rotavirus, has caused epidemics of severe diarrhea in China, India, and Bangladesh. Thousands of people are infected in a single RVB epidemic. However, information on this group of rotaviruses remains limited. As NSP2 is an essential protein in the viral life cycle, including its role in the formation of replication factories, it may be a target for future antiviral strategy against viruses with similar mechanisms.
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Affiliation(s)
- Sebastian Chamera
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Krzysztof Wycisk
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | | | - Marcin Nowotny
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, Warsaw, Poland
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3
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Flexibility of the Rotavirus NSP2 C-Terminal Region Supports Factory Formation via Liquid-Liquid Phase Separation. J Virol 2023; 97:e0003923. [PMID: 36749077 PMCID: PMC9973012 DOI: 10.1128/jvi.00039-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Many viruses sequester the materials needed for their replication into discrete subcellular factories. For rotaviruses (RVs), these factories are called viroplasms, and they are formed in the host cell cytosol via the process of liquid-liquid phase separation (LLPS). The nonstructural protein 2 (NSP2) and its binding partner, nonstructural protein 5 (NSP5), are critical for viroplasm biogenesis. Yet it is not fully understood how NSP2 and NSP5 cooperate to form factories. The C-terminal region (CTR) of NSP2 (residues 291 to 317) is flexible, allowing it to participate in domain-swapping interactions that promote interoctamer interactions and, presumably, viroplasm formation. Molecular dynamics simulations showed that a lysine-to-glutamic acid change at position 294 (K294E) reduces NSP2 CTR flexibility in silico. To test the impact of reduced NSP2 CTR flexibility during infection, we engineered a mutant RV bearing this change (rRV-NSP2K294E). Single-cycle growth assays revealed a >1.2-log reduction in endpoint titers for rRV-NSP2K294E versus the wild-type control (rRV-WT). Using immunofluorescence assays, we found that rRV-NSP2K294E formed smaller, more numerous viroplasms than rRV-WT. Live-cell imaging experiments confirmed these results and revealed that rRV-NSP2K294E factories had delayed fusion kinetics. Moreover, NSP2K294E and several other CTR mutants formed fewer viroplasm-like structures in NSP5 coexpressing cells than did control NSP2WT. Finally, NSP2K294E exhibited defects in its capacity to induce LLPS droplet formation in vitro when incubated alongside NSP5. These results underscore the importance of NSP2 CTR flexibility in supporting the biogenesis of RV factories. IMPORTANCE Viruses often condense the materials needed for their replication into discrete intracellular factories. For rotaviruses, agents of severe gastroenteritis in children, factory formation is mediated in part by an octameric protein called NSP2. A flexible C-terminal region of NSP2 has been proposed to link several NSP2 octamers together, a feature that might be important for factory formation. Here, we created a change in NSP2 that reduced C-terminal flexibility and analyzed the impact on rotavirus factories. We found that the change caused the formation of smaller and more numerous factories that could not readily fuse together like those of the wild-type virus. The altered NSP2 protein also had a reduced capacity to form factory-like condensates in a test tube. Together, these results add to our growing understanding of how NSP2 supports rotavirus factory formation-a key step of viral replication.
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A Fijivirus Major Viroplasm Protein Shows RNA-Stimulated ATPase Activity by Adopting Pentameric and Hexameric Assemblies of Dimers. mBio 2023; 14:e0002323. [PMID: 36786587 PMCID: PMC10128069 DOI: 10.1128/mbio.00023-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
Fijiviruses replicate and package their genomes within viroplasms in a process involving RNA-RNA and RNA-protein interactions. Here, we demonstrate that the 24 C-terminal residues (C-arm) of the P9-1 major viroplasm protein of the mal de Río Cuarto virus (MRCV) are required for its multimerization and the formation of viroplasm-like structures. Using an integrative structural approach, the C-arm was found to be dispensable for P9-1 dimer assembly but essential for the formation of pentamers and hexamers of dimers (decamers and dodecamers), which favored RNA binding. Although both P9-1 and P9-1ΔC-arm catalyzed ATP with similar activities, an RNA-stimulated ATPase activity was only detected in the full-length protein, indicating a C-arm-mediated interaction between the ATP catalytic site and the allosteric RNA binding sites in the (do)decameric assemblies. A stronger preference to bind phosphate moieties in the decamer was predicted, suggesting that the allosteric modulation of ATPase activity by RNA is favored in this structural conformation. Our work reveals the structural versatility of a fijivirus major viroplasm protein and provides clues to its mechanism of action. IMPORTANCE The mal de Río Cuarto virus (MRCV) causes an important maize disease in Argentina. MRCV replicates in several species of Gramineae plants and planthopper vectors. The viral factories, also called viroplasms, have been studied in detail in animal reovirids. This work reveals that a major viroplasm protein of MRCV forms previously unidentified structural arrangements and provides evidence that it may simultaneously adopt two distinct quaternary assemblies. Furthermore, our work uncovers an allosteric communication between the ATP and RNA binding sites that is favored in the multimeric arrangements. Our results contribute to the understanding of plant reovirids viroplasm structure and function and pave the way for the design of antiviral strategies for disease control.
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Amimo JO, Raev SA, Chepngeno J, Mainga AO, Guo Y, Saif L, Vlasova AN. Rotavirus Interactions With Host Intestinal Epithelial Cells. Front Immunol 2022; 12:793841. [PMID: 35003114 PMCID: PMC8727603 DOI: 10.3389/fimmu.2021.793841] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 12/06/2021] [Indexed: 12/13/2022] Open
Abstract
Rotavirus (RV) is the foremost enteric pathogen associated with severe diarrheal illness in young children (<5years) and animals worldwide. RV primarily infects mature enterocytes in the intestinal epithelium causing villus atrophy, enhanced epithelial cell turnover and apoptosis. Intestinal epithelial cells (IECs) being the first physical barrier against RV infection employs a range of innate immune strategies to counteract RVs invasion, including mucus production, toll-like receptor signaling and cytokine/chemokine production. Conversely, RVs have evolved numerous mechanisms to escape/subvert host immunity, seizing translation machinery of the host for effective replication and transmission. RV cell entry process involve penetration through the outer mucus layer, interaction with cell surface molecules and intestinal microbiota before reaching the IECs. For successful cell attachment and entry, RVs use sialic acid, histo-blood group antigens, heat shock cognate protein 70 and cell-surface integrins as attachment factors and/or (co)-receptors. In this review, a comprehensive summary of the existing knowledge of mechanisms underlying RV-IECs interactions, including the role of gut microbiota, during RV infection is presented. Understanding these mechanisms is imperative for developing efficacious strategies to control RV infections, including development of antiviral therapies and vaccines that target specific immune system antagonists within IECs.
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Affiliation(s)
- Joshua Oluoch Amimo
- Center for Food Animal Health, Department of Animal Sciences, College of Food Agricultural and Environmental Sciences, The Ohio State University, Wooster, OH, United States.,Department of Animal Production, Faculty of Veterinary Medicine, University of Nairobi, Nairobi, Kenya
| | - Sergei Alekseevich Raev
- Center for Food Animal Health, Department of Animal Sciences, College of Food Agricultural and Environmental Sciences, The Ohio State University, Wooster, OH, United States
| | - Juliet Chepngeno
- Center for Food Animal Health, Department of Animal Sciences, College of Food Agricultural and Environmental Sciences, The Ohio State University, Wooster, OH, United States
| | - Alfred Omwando Mainga
- Center for Food Animal Health, Department of Animal Sciences, College of Food Agricultural and Environmental Sciences, The Ohio State University, Wooster, OH, United States.,Department of Public Health, Pharmacology and Toxicology, Faculty of Veterinary Medicine, University of Nairobi, Nairobi, Kenya
| | - Yusheng Guo
- Center for Food Animal Health, Department of Animal Sciences, College of Food Agricultural and Environmental Sciences, The Ohio State University, Wooster, OH, United States
| | - Linda Saif
- Center for Food Animal Health, Department of Animal Sciences, College of Food Agricultural and Environmental Sciences, The Ohio State University, Wooster, OH, United States
| | - Anastasia N Vlasova
- Center for Food Animal Health, Department of Animal Sciences, College of Food Agricultural and Environmental Sciences, The Ohio State University, Wooster, OH, United States
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6
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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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Bravo JPK, Bartnik K, Venditti L, Acker J, Gail EH, Colyer A, Davidovich C, Lamb DC, Tuma R, Calabrese AN, Borodavka A. Structural basis of rotavirus RNA chaperone displacement and RNA annealing. Proc Natl Acad Sci U S A 2021; 118:e2100198118. [PMID: 34615715 PMCID: PMC8521686 DOI: 10.1073/pnas.2100198118] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/12/2021] [Indexed: 01/13/2023] Open
Abstract
Rotavirus genomes are distributed between 11 distinct RNA molecules, all of which must be selectively copackaged during virus assembly. This likely occurs through sequence-specific RNA interactions facilitated by the RNA chaperone NSP2. Here, we report that NSP2 autoregulates its chaperone activity through its C-terminal region (CTR) that promotes RNA-RNA interactions by limiting its helix-unwinding activity. Unexpectedly, structural proteomics data revealed that the CTR does not directly interact with RNA, while accelerating RNA release from NSP2. Cryo-electron microscopy reconstructions of an NSP2-RNA complex reveal a highly conserved acidic patch on the CTR, which is poised toward the bound RNA. Virus replication was abrogated by charge-disrupting mutations within the acidic patch but completely restored by charge-preserving mutations. Mechanistic similarities between NSP2 and the unrelated bacterial RNA chaperone Hfq suggest that accelerating RNA dissociation while promoting intermolecular RNA interactions may be a widespread strategy of RNA chaperone recycling.
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Affiliation(s)
- Jack P K Bravo
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, LS2 9JT Leeds, United Kingdom
| | - Kira Bartnik
- Department of Chemistry, Center for NanoScience, Nanosystems Initiative Munich, Centre for Integrated Protein Science Munich, Ludwig Maximilian University of Munich, D-81377 Munich, Germany
| | - Luca Venditti
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
| | - Julia Acker
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
| | - Emma H Gail
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC 3800, Australia
- Australian Research Council (ARC) Centre of Excellence in Advanced Molecular Imaging, European Molecular Biology Laboratory (EMBL) Australia, Clayton, VIC 3800, Australia
| | - Alice Colyer
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, LS2 9JT Leeds, United Kingdom
| | - Chen Davidovich
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC 3800, Australia
- Australian Research Council (ARC) Centre of Excellence in Advanced Molecular Imaging, European Molecular Biology Laboratory (EMBL) Australia, Clayton, VIC 3800, Australia
| | - Don C Lamb
- Department of Chemistry, Center for NanoScience, Nanosystems Initiative Munich, Centre for Integrated Protein Science Munich, Ludwig Maximilian University of Munich, D-81377 Munich, Germany
| | - Roman Tuma
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, LS2 9JT Leeds, United Kingdom
- Faculty of Science, University of South Bohemia, 370 05 Ceske Budejovice, Czech Republic
| | - Antonio N Calabrese
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, LS2 9JT Leeds, United Kingdom
| | - Alexander Borodavka
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom;
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, LS2 9JT Leeds, United Kingdom
- Department of Chemistry, Center for NanoScience, Nanosystems Initiative Munich, Centre for Integrated Protein Science Munich, Ludwig Maximilian University of Munich, D-81377 Munich, Germany
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Hoxie I, Dennehy JJ. Rotavirus A Genome Segments Show Distinct Segregation and Codon Usage Patterns. Viruses 2021; 13:v13081460. [PMID: 34452326 PMCID: PMC8402926 DOI: 10.3390/v13081460] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 07/05/2021] [Accepted: 07/07/2021] [Indexed: 12/29/2022] Open
Abstract
Reassortment of the Rotavirus A (RVA) 11-segment dsRNA genome may generate new genome constellations that allow RVA to expand its host range or evade immune responses. Reassortment may also produce phylogenetic incongruities and weakly linked evolutionary histories across the 11 segments, obscuring reassortment-specific epistasis and changes in substitution rates. To determine the co-segregation patterns of RVA segments, we generated time-scaled phylogenetic trees for each of the 11 segments of 789 complete RVA genomes isolated from mammalian hosts and compared the segments’ geodesic distances. We found that segments 4 (VP4) and 9 (VP7) occupied significantly different tree spaces from each other and from the rest of the genome. By contrast, segments 10 and 11 (NSP4 and NSP5/6) occupied nearly indistinguishable tree spaces, suggesting strong co-segregation. Host-species barriers appeared to vary by segment, with segment 9 (VP7) presenting the weakest association with host species. Bayesian Skyride plots were generated for each segment to compare relative genetic diversity among segments over time. All segments showed a dramatic decrease in diversity around 2007 coinciding with the introduction of RVA vaccines. To assess selection pressures, codon adaptation indices and relative codon deoptimization indices were calculated with respect to different host genomes. Codon usage varied by segment with segment 11 (NSP5) exhibiting significantly higher adaptation to host genomes. Furthermore, RVA codon usage patterns appeared optimized for expression in humans and birds relative to the other hosts examined, suggesting that translational efficiency is not a barrier in RVA zoonosis.
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Affiliation(s)
- Irene Hoxie
- Biology Department, The Graduate Center, The City University of New York, New York, NY 10016, USA;
- Biology Department, Queens College, The City University of New York, Flushing, New York, NY 11367, USA
- Correspondence:
| | - John J. Dennehy
- Biology Department, The Graduate Center, The City University of New York, New York, NY 10016, USA;
- Biology Department, Queens College, The City University of New York, Flushing, New York, NY 11367, USA
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9
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Devi YD, Devi A, Gogoi H, Dehingia B, Doley R, Buragohain AK, Singh CS, Borah PP, Rao CD, Ray P, Varghese GM, Kumar S, Namsa ND. Exploring rotavirus proteome to identify potential B- and T-cell epitope using computational immunoinformatics. Heliyon 2020; 6:e05760. [PMID: 33426322 PMCID: PMC7779714 DOI: 10.1016/j.heliyon.2020.e05760] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 11/02/2020] [Accepted: 12/14/2020] [Indexed: 11/28/2022] Open
Abstract
Rotavirus is the most common cause of acute gastroenteritis in infants and children worldwide. The functional correlation of B- and T-cells to long-lasting immunity against rotavirus infection in the literature is limited. In this work, a series of computational immuno-informatics approaches were applied and identified 28 linear B-cells, 26 conformational B-cell, 44 TC cell and 40 TH cell binding epitopes for structural and non-structural proteins of rotavirus. Further selection of putative B and T cell epitopes in the multi-epitope vaccine construct was carried out based on immunogenicity, conservancy, allergenicity and the helical content of predicted epitopes. An in-silico vaccine constructs was developed using an N-terminal adjuvant (RGD motif) followed by TC and TH cell epitopes and B-cell epitope with an appropriate linker. Multi-threading models of multi-epitope vaccine construct with B- and T-cell epitopes were generated and molecular dynamics simulation was performed to determine the stability of designed vaccine. Codon optimized multi-epitope vaccine antigens was expressed and affinity purified using the E. coli expression system. Further the T cell epitope presentation assay using the recombinant multi-epitope constructs and the T cell epitope predicted and identified in this study have not been investigated. Multi-epitope vaccine construct encompassing predicted B- and T-cell epitopes may help to generate long-term immune responses against rotavirus. The computational findings reported in this study may provide information in developing epitope-based vaccine and diagnostic assay for rotavirus-led diarrhea in children's.
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Affiliation(s)
- Yengkhom Damayanti Devi
- Department of Molecular Biology and Biotechnology, Tezpur University, Napaam 784 028, Assam, India
| | - Arpita Devi
- Department of Molecular Biology and Biotechnology, Tezpur University, Napaam 784 028, Assam, India
| | - Hemanga Gogoi
- Department of Molecular Biology and Biotechnology, Tezpur University, Napaam 784 028, Assam, India
| | - Bondita Dehingia
- Department of Molecular Biology and Biotechnology, Tezpur University, Napaam 784 028, Assam, India
| | - Robin Doley
- Department of Molecular Biology and Biotechnology, Tezpur University, Napaam 784 028, Assam, India
| | | | - Ch Shyamsunder Singh
- Department of Paediatrics, Regional Institute of Medical Sciences, Imphal, India
| | - Partha Pratim Borah
- Department of Paediatrics and Neonatology, Pratiksha Hospital, Guwahati, India
| | - C Durga Rao
- School of Liberal Arts and Basic Sciences, SRM University AP, Amaravati, India
| | - Pratima Ray
- Department of Biotechnology, Jamia Hamdard, Delhi, India
| | - George M Varghese
- Department of Infectious Diseases, Christian Medical College, Vellore, India
| | - Sachin Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Guwahati, India
| | - Nima D Namsa
- Department of Molecular Biology and Biotechnology, Tezpur University, Napaam 784 028, Assam, India
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10
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Criglar JM, Crawford SE, Zhao B, Smith HG, Stossi F, Estes MK. A Genetically Engineered Rotavirus NSP2 Phosphorylation Mutant Impaired in Viroplasm Formation and Replication Shows an Early Interaction between vNSP2 and Cellular Lipid Droplets. J Virol 2020; 94:e00972-20. [PMID: 32461314 PMCID: PMC7375380 DOI: 10.1128/jvi.00972-20] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 05/21/2020] [Indexed: 12/18/2022] Open
Abstract
Many RNA viruses replicate in cytoplasmic compartments (virus factories or viroplasms) composed of viral and cellular proteins, but the mechanisms required for their formation remain largely unknown. Rotavirus (RV) replication in viroplasms requires interactions between virus nonstructural proteins NSP2 and NSP5, which are associated with components of lipid droplets (LDs). We previously identified two forms of NSP2 in RV-infected cells, a cytoplasmically dispersed form (dNSP2) and a viroplasm-specific form (vNSP2), which interact with hypophosphorylated and hyperphosphorylated NSP5, respectively, indicating that a coordinated phosphorylation cascade controls viroplasm assembly. The cellular kinase CK1α phosphorylates NSP2 on serine 313, triggering the localization of vNSP2 to sites of viroplasm assembly and its association with hyperphosphorylated NSP5. Using reverse genetics, we generated a rotavirus with a phosphomimetic NSP2 (S313D) mutation to directly evaluate the role of CK1α NSP2 phosphorylation in viroplasm formation. Recombinant rotavirus NSP2 S313D (rRV NSP2 S313D) is significantly delayed in viroplasm formation and in virus replication and interferes with wild-type RV replication in coinfection. Taking advantage of the delay in viroplasm formation, the NSP2 phosphomimetic mutant was used as a tool to observe very early events in viroplasm assembly. We show that (i) viroplasm assembly correlates with NSP5 hyperphosphorylation and (ii) vNSP2 S313D colocalizes with RV-induced LDs without NSP5, suggesting that vNSP2 phospho-S313 is sufficient for interacting with LDs and may be the virus factor required for RV-induced LD formation. Further studies with the rRV NSP2 S313D virus are expected to reveal new aspects of viroplasm and LD initiation and assembly.IMPORTANCE Reverse genetics was used to generate a recombinant rotavirus with a single phosphomimetic mutation in nonstructural protein 2 (NSP2 S313D) that exhibits delayed viroplasm formation, delayed replication, and an interfering phenotype during coinfection with wild-type rotavirus, indicating the importance of this amino acid during virus replication. Exploiting the delay in viroplasm assembly, we found that viroplasm-associated NSP2 colocalizes with rotavirus-induced lipid droplets prior to the accumulation of other rotavirus proteins that are required for viroplasm formation and that NSP5 hyperphosphorylation is required for viroplasm assembly. These data suggest that NSP2 phospho-S313 is sufficient for interaction with lipid droplets and may be the virus factor that induces lipid droplet biogenesis in rotavirus-infected cells. Lipid droplets are cellular organelles critical for the replication of many viral and bacterial pathogens, and thus, understanding the mechanism of NSP2-mediated viroplasm/lipid droplet initiation and interaction will lead to new insights into this important host-pathogen interaction.
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Affiliation(s)
- Jeanette M Criglar
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
| | - Sue E Crawford
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
| | - Boyang Zhao
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
| | - Hunter G Smith
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
| | - Fabio Stossi
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
- Integrated Microscopy Core, Baylor College of Medicine, Houston, Texas, USA
| | - Mary K Estes
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
- Department of Medicine, Division of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, Texas, USA
- Department of Medicine, Division of Infectious Diseases, Baylor College of Medicine, Houston, Texas, USA
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11
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Kaelber JT, Jiang W, Weaver SC, Auguste AJ, Chiu W. Arrangement of the Polymerase Complexes inside a Nine-Segmented dsRNA Virus. Structure 2020; 28:604-612.e3. [PMID: 32049031 PMCID: PMC7289189 DOI: 10.1016/j.str.2020.01.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 12/18/2019] [Accepted: 01/17/2020] [Indexed: 12/15/2022]
Abstract
Members of the family Reoviridae package several copies of the viral polymerase complex into their capsid to carry out replication and transcription within viral particles. Classical single-particle reconstruction encounters difficulties resolving structures such as the intraparticle polymerase complex because refinement can converge to an incorrect map and because the map could depict a nonrepresentative subset of particles or an average of heterogeneous particles. Using the nine-segmented Fako virus, we tested hypotheses for the arrangement and number of polymerase complexes within the virion by measuring how well each hypothesis describes the set of cryoelectron microscopy images of individual viral particles. We find that the polymerase complex in Fako virus binds at ten possible sites despite having only nine genome segments. A single asymmetric configuration describes the arrangement of these complexes in both virions and genome-free capsids. Similarities between the arrangements of Reoviridae with 9, 10, and 11 segments indicate the generalizability of this architecture.
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Affiliation(s)
- Jason T Kaelber
- Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, NJ, USA.
| | - Wen Jiang
- Markey Center for Structural Biology, Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
| | - Scott C Weaver
- Institute for Human Infections and Immunity, World Reference Center for Emerging Viruses and Arboviruses, Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA
| | - Albert J Auguste
- Institute for Human Infections and Immunity, World Reference Center for Emerging Viruses and Arboviruses, Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA; Department of Entomology, Fralin Life Science Institute, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Wah Chiu
- Department of Bioengineering, Department of Microbiology and Immunology, and James H. Clark Center, Stanford University, Stanford, CA, USA
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12
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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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13
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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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14
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Bravo JPK, Borodavka A, Barth A, Calabrese AN, Mojzes P, Cockburn JJB, Lamb DC, Tuma R. Stability of local secondary structure determines selectivity of viral RNA chaperones. Nucleic Acids Res 2018; 46:7924-7937. [PMID: 29796667 PMCID: PMC6125681 DOI: 10.1093/nar/gky394] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 04/24/2018] [Accepted: 04/30/2018] [Indexed: 01/02/2023] Open
Abstract
To maintain genome integrity, segmented double-stranded RNA viruses of the Reoviridae family must accurately select and package a complete set of up to a dozen distinct genomic RNAs. It is thought that the high fidelity segmented genome assembly involves multiple sequence-specific RNA-RNA interactions between single-stranded RNA segment precursors. These are mediated by virus-encoded non-structural proteins with RNA chaperone-like activities, such as rotavirus (RV) NSP2 and avian reovirus σNS. Here, we compared the abilities of NSP2 and σNS to mediate sequence-specific interactions between RV genomic segment precursors. Despite their similar activities, NSP2 successfully promotes inter-segment association, while σNS fails to do so. To understand the mechanisms underlying such selectivity in promoting inter-molecular duplex formation, we compared RNA-binding and helix-unwinding activities of both proteins. We demonstrate that octameric NSP2 binds structured RNAs with high affinity, resulting in efficient intramolecular RNA helix disruption. Hexameric σNS oligomerizes into an octamer that binds two RNAs, yet it exhibits only limited RNA-unwinding activity compared to NSP2. Thus, the formation of intersegment RNA-RNA interactions is governed by both helix-unwinding capacity of the chaperones and stability of RNA structure. We propose that this protein-mediated RNA selection mechanism may underpin the high fidelity assembly of multi-segmented RNA genomes in Reoviridae.
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Affiliation(s)
- Jack P K Bravo
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
- School of Molecular and Cellular Biology, University of Leeds, Leeds, UK
| | - Alexander Borodavka
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
- School of Molecular and Cellular Biology, University of Leeds, Leeds, UK
- Department of Chemistry, Center for NanoScience (CeNS), Nanosystems Initiative Munich (NIM) and Centre for Integrated Protein Science Munich (CiPSM), Ludwig Maximilian University of Munich, Munich, Germany
| | - Anders Barth
- Department of Chemistry, Center for NanoScience (CeNS), Nanosystems Initiative Munich (NIM) and Centre for Integrated Protein Science Munich (CiPSM), Ludwig Maximilian University of Munich, Munich, Germany
| | - Antonio N Calabrese
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
- School of Molecular and Cellular Biology, University of Leeds, Leeds, UK
| | - Peter Mojzes
- Institute of Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, CZ-12116 Prague 2, Czech Republic
| | - Joseph J B Cockburn
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
- School of Molecular and Cellular Biology, University of Leeds, Leeds, UK
| | - Don C Lamb
- Department of Chemistry, Center for NanoScience (CeNS), Nanosystems Initiative Munich (NIM) and Centre for Integrated Protein Science Munich (CiPSM), Ludwig Maximilian University of Munich, Munich, Germany
| | - Roman Tuma
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
- School of Molecular and Cellular Biology, University of Leeds, Leeds, UK
- Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic
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15
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Borodavka A, Dykeman EC, Schrimpf W, Lamb DC. Protein-mediated RNA folding governs sequence-specific interactions between rotavirus genome segments. eLife 2017; 6:27453. [PMID: 28922109 PMCID: PMC5621836 DOI: 10.7554/elife.27453] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 08/03/2017] [Indexed: 01/06/2023] Open
Abstract
Segmented RNA viruses are ubiquitous pathogens, which include influenza viruses and rotaviruses. A major challenge in understanding their assembly is the combinatorial problem of a non-random selection of a full genomic set of distinct RNAs. This process involves complex RNA-RNA and protein-RNA interactions, which are often obscured by non-specific binding at concentrations approaching in vivo assembly conditions. Here, we present direct experimental evidence of sequence-specific inter-segment interactions between rotavirus RNAs, taking place in a complex RNA- and protein-rich milieu. We show that binding of the rotavirus-encoded non-structural protein NSP2 to viral ssRNAs results in the remodeling of RNA, which is conducive to formation of stable inter-segment contacts. To identify the sites of these interactions, we have developed an RNA-RNA SELEX approach for mapping the sequences involved in inter-segment base-pairing. Our findings elucidate the molecular basis underlying inter-segment interactions in rotaviruses, paving the way for delineating similar RNA-RNA interactions that govern assembly of other segmented RNA viruses. Rotavirus is a highly infectious virus that affects children worldwide, causing severe diarrhoea. Despite the introduction of several highly effective vaccines, more than 200,000 children still die from rotavirus each year. There are currently no drugs that can combat this disease once a child has been infected. Viruses carry the instructions that determine their properties and behavior in molecules of DNA or RNA. Unlike many other viruses, which typically have a single molecule of DNA or RNA, rotavirus has 11 distinct “RNA segments”. After invading a cell the virus begins to replicate itself. During replication, the RNA segments (which consist of two strands of RNA paired together) are copied many times. It is not clear how rotaviruses ‘count’ up to 11 so that each new virus acquires a single copy of each segment. Previous biochemical and structural studies of rotavirus replication suggest that selecting 11 distinct RNA segments must involve the RNAs forming complex interactions with proteins and other RNA molecules. Using a highly sensitive fluorescence-based approach, termed fluorescence cross-correlation spectroscopy, Borodavka et al. now present direct experimental evidence of interactions between the RNA segments that occur via single strands of the rotavirus RNA. These RNA-RNA interactions require the binding of a rotavirus protein NSP2 to the RNA strands, which results in the remodeling of the RNA; this remodeling is required to form stable contacts between different RNA segments. Furthermore, a new experimental approach (called RNA-RNA SELEX) developed by Borodavka et al. identified the parts of the RNA segments that may take part in these interactions. The results presented by Borodavka et al. pave the way for identifying the RNA-RNA interactions that govern how other segmented RNA viruses can package their genetic material. Further work to uncover the entire RNA interaction network in rotaviruses would also accelerate the design of new vaccines and may help us to develop antiviral drugs to treat infections.
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Affiliation(s)
- Alexander Borodavka
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom.,Department of Chemistry, Center for NanoScience, Nanosystems Initiative Munich (NIM) and Center for Integrated Protein Science Munich (CiPSM), Ludwig-Maximilian University of Munich, Munich, Germany
| | - Eric C Dykeman
- York Centre for Complex Systems Analysis, University of York, York, United Kingdom.,Department of Mathematics, University of York, York, United Kingdom.,Department of Biology, University of York, York, United Kingdom
| | - Waldemar Schrimpf
- Department of Chemistry, Center for NanoScience, Nanosystems Initiative Munich (NIM) and Center for Integrated Protein Science Munich (CiPSM), Ludwig-Maximilian University of Munich, Munich, Germany
| | - Don C Lamb
- Department of Chemistry, Center for NanoScience, Nanosystems Initiative Munich (NIM) and Center for Integrated Protein Science Munich (CiPSM), Ludwig-Maximilian University of Munich, Munich, Germany
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16
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Single-Particle Detection of Transcription following Rotavirus Entry. J Virol 2017; 91:JVI.00651-17. [PMID: 28701394 PMCID: PMC5571246 DOI: 10.1128/jvi.00651-17] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2017] [Accepted: 06/29/2017] [Indexed: 12/25/2022] Open
Abstract
Infectious rotavirus particles are triple-layered, icosahedral assemblies. The outer layer proteins, VP4 (cleaved to VP8* and VP5*) and VP7, surround a transcriptionally competent, double-layer particle (DLP), which they deliver into the cytosol. During entry of rhesus rotavirus, VP8* interacts with cell surface gangliosides, allowing engulfment into a membrane vesicle by a clathrin-independent process. Escape into the cytosol and outer-layer shedding depend on interaction of a hydrophobic surface on VP5* with the membrane bilayer and on a large-scale conformational change. We report here experiments that detect the fate of released DLPs and their efficiency in initiating RNA synthesis. By replacing the outer layer with fluorescently tagged, recombinant proteins and also tagging the DLP, we distinguished particles that have lost their outer layer and entered the cytosol (uncoated) from those still within membrane vesicles. We used fluorescent in situ hybridization with probes for nascent transcripts to determine how soon after uncoating transcription began and what fraction of the uncoated particles were active in initiating RNA synthesis. We detected RNA synthesis by uncoated particles as early as 15 min after adding virus. The uncoating efficiency was 20 to 50%; of the uncoated particles, about 10 to 15% synthesized detectable RNA. In the format of our experiments, about 10% of the added particles attached to the cell surface, giving an overall ratio of added particles to RNA-synthesizing particles of between 250:1 and 500:1, in good agreement with the ratio of particles to focus-forming units determined by infectivity assays. Thus, RNA synthesis by even a single, uncoated particle can initiate infection in a cell.IMPORTANCE The pathways by which a virus enters a cell transform its packaged genome into an active one. Contemporary fluorescence microscopy can detect individual virus particles as they enter cells, allowing us to map their multistep entry pathways. Rotaviruses, like most viruses that lack membranes of their own, disrupt or perforate the intracellular, membrane-enclosed compartment into which they become engulfed following attachment to a cell surface, in order to gain access to the cell interior. The properties of rotavirus particles make it possible to determine molecular mechanisms for these entry steps. In the work described here, we have asked the following question: what fraction of the rotavirus particles that penetrate into the cell make new viral RNA? We find that of the cell-attached particles, between 20 and 50% ultimately penetrate, and of these, about 10% make RNA. RNA synthesis by even a single virus particle can initiate a productive infection.
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17
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Crawford SE, Desselberger U. Lipid droplets form complexes with viroplasms and are crucial for rotavirus replication. Curr Opin Virol 2016; 19:11-5. [PMID: 27341619 DOI: 10.1016/j.coviro.2016.05.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 05/18/2016] [Accepted: 05/23/2016] [Indexed: 10/25/2022]
Abstract
Recent evidence has demonstrated that a variety of pathogens target cellular lipid metabolism for their replication. Lipid droplets are a major contributor to lipid homeostasis and contain neutral fats but are also recognized as dynamic organelles involved in signal transduction, membrane trafficking and modulation of immune and inflammatory responses. Rotaviruses co-opt lipid droplets for their replication. Rotavirus viroplasms, sites of viral RNA replication and immature particle assembly, form complexes with cellular lipid droplets early in infection. Chemical compounds blocking fatty acid synthesis or interfering with lipid droplet homeostasis decrease viroplasm formation and the yield of infectious viral progeny. Lipid droplets are vital for the replication of rotaviruses as well as various members of the Flaviviridae family and several intracellular bacteria. Chemical compounds decreasing intracellular triglyceride content reduced rotavirus replication in an animal model and should be considered as potential therapeutic agents against disease caused by rotaviruses, flaviviruses and intracellular bacteria.
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Affiliation(s)
- Sue E Crawford
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA.
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18
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Chen Q, Chen H, Jia D, Mao Q, Xei L, Wei T. Nonstructural protein Pns12 of rice dwarf virus is a principal regulator for viral replication and infection in its insect vector. Virus Res 2015. [PMID: 26200955 DOI: 10.1016/j.virusres.2015.07.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Plant reoviruses are thought to replicate and assemble within cytoplasmic structures called viroplasms. The molecular mechanisms underling the formation of the viroplasm during infection of rice dwarf virus (RDV), a plant reovirus, in its leafhopper vector cells remain poorly understood. Viral nonstructural protein Pns12 forms viroplasm-like inclusions in the absence of viral infection, suggesting that the viroplasm matrix is basically composed of Pns12. Here, we demonstrated that core capsid protein P3 and nonstructural protein Pns11 were recruited in the viroplasm by direct interaction with Pns12, whereas nonstructural protein Pns6 was recruited through interaction with Pns11. The introduction of dsRNA from Pns12 gene into cultured insect vector cells or intact insect strongly inhibited such viroplasm formation, preventing efficient viral spread in the leafhopper in vitro and in vivo. Thus, nonstructural protein Pns12 of RDV is a principal regulator for viral replication and infection in its insect vector.
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Affiliation(s)
- Qian Chen
- Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, PR China
| | - Hongyan Chen
- Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, PR China
| | - Dongsheng Jia
- Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, PR China
| | - Qianzhuo Mao
- Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, PR China
| | - Lianhui Xei
- Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, PR China.
| | - Taiyun Wei
- Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, PR China.
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19
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Boudreaux CE, Kelly DF, McDonald SM. Electron microscopic analysis of rotavirus assembly-replication intermediates. Virology 2015; 477:32-41. [PMID: 25635339 PMCID: PMC4359669 DOI: 10.1016/j.virol.2015.01.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 12/14/2014] [Accepted: 01/05/2015] [Indexed: 11/24/2022]
Abstract
Rotaviruses (RVs) replicate their segmented, double-stranded RNA genomes in tandem with early virion assembly. In this study, we sought to gain insight into the ultrastructure of RV assembly-replication intermediates (RIs) using transmission electron microscopy (EM). Specifically, we examined a replicase-competent, subcellular fraction that contains all known RV RIs. Three never-before-seen complexes were visualized in this fraction. Using in vitro reconstitution, we showed that ~15-nm doughnut-shaped proteins in strings were nonstructural protein 2 (NSP2) bound to viral RNA transcripts. Moreover, using immunoaffinity-capture EM, we revealed that ~20-nm pebble-shaped complexes contain the viral RNA polymerase (VP1) and RNA capping enzyme (VP3). Finally, using a gel purification method, we demonstrated that ~30–70-nm electron-dense, particle-shaped complexes represent replicase-competent core RIs, containing VP1, VP3, and NSP2 as well as capsid proteins VP2 and VP6. The results of this study raise new questions about the interactions among viral proteins and RNA during the concerted assembly-replicase process.
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Affiliation(s)
- Crystal E Boudreaux
- Virginia Tech Carilion School of Medicine and Research Institute, Roanoke, VA, USA
| | - Deborah F Kelly
- Virginia Tech Carilion School of Medicine and Research Institute, Roanoke, VA, USA
| | - Sarah M McDonald
- Virginia Tech Carilion School of Medicine and Research Institute, Roanoke, VA, USA; Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg, VA, USA.
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20
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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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21
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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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22
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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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Miyazaki N, Nakagawa A, Iwasaki K. Life cycle of phytoreoviruses visualized by electron microscopy and tomography. Front Microbiol 2013; 4:306. [PMID: 24137159 PMCID: PMC3797527 DOI: 10.3389/fmicb.2013.00306] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 09/24/2013] [Indexed: 12/30/2022] Open
Abstract
Rice dwarf virus and Rice gall dwarf virus, members of the genus Phytoreovirus in the family Reoviridae,are known as agents of rice disease, because their spread results in substantial economic damage in many Asian countries. These viruses are transmitted via insect vectors, and they multiply both in the plants and in the insect vectors. Structural information about the viruses and their interactions with cellular components in the life cycle are essential for understanding viral infection and replication mechanisms. The life cycle of the viruses involves various cellular events such as cell entry, synthesis of viral genome and proteins, assembly of viral components, viral egress from infected cells, and intra- and intercellular transports. This review focuses on the major events underlying the life cycle of phytoreoviruses, which has been visualized by various electron microscopy (EM) imaging techniques, including cryo-electron microscopy and tomography, and demonstrates the advantage of the advanced EM imaging techniques to investigate the viral infection and replication mechanisms.
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Affiliation(s)
- Naoyuki Miyazaki
- Institute for Protein Research, Osaka University Osaka, Japan ; National Institute for Physiological Sciences Okazaki, Japan
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Activation of the endoplasmic reticulum calcium sensor STIM1 and store-operated calcium entry by rotavirus requires NSP4 viroporin activity. J Virol 2013; 87:13579-88. [PMID: 24109210 DOI: 10.1128/jvi.02629-13] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Rotavirus nonstructural protein 4 (NSP4) induces dramatic changes in cellular calcium homeostasis. These include increased endoplasmic reticulum (ER) permeability, resulting in decreased ER calcium stores and activation of plasma membrane (PM) calcium influx channels, ultimately causing a 2- to 4-fold elevation in cytoplasmic calcium. Elevated cytoplasmic calcium is absolutely required for virus replication, but the underlying mechanisms responsible for calcium influx remain poorly understood. NSP4 is an ER-localized viroporin, whose activity depletes ER calcium, which ultimately leads to calcium influx. We hypothesized that NSP4-mediated depletion of ER calcium activates store-operated calcium entry (SOCE) through activation of the ER calcium sensor stromal interaction molecule 1 (STIM1). We established and used a stable yellow fluorescent protein-expressing STIM1 cell line (YFP-STIM1) as a biosensor to assess STIM1 activation (puncta formation) by rotavirus infection and NSP4 expression. We found that STIM1 is constitutively active in rotavirus-infected cells and that STIM1 puncta colocalize with the PM-localized Orai1 SOCE calcium channel. Expression of wild-type NSP4 activated STIM1, resulting in PM calcium influx, but an NSP4 viroporin mutant failed to induce STIM1 activation and did not activate the PM calcium entry pathway. Finally, knockdown of STIM1 significantly reduced rotavirus yield, indicating STIM1 plays a critical role in virus replication. These data demonstrate that while rotavirus may ultimately activate multiple calcium channels in the PM, calcium influx is predicated on NSP4 viroporin-mediated activation of STIM1 in the ER. This is the first report of viroporin-mediated activation of SOCE, reinforcing NSP4 as a robust model to understand dysregulation of calcium homeostasis during virus infections.
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Viroplasm protein P9-1 of Rice black-streaked dwarf virus preferentially binds to single-stranded RNA in its octamer form, and the central interior structure formed by this octamer constitutes the major RNA binding site. J Virol 2013; 87:12885-99. [PMID: 24067964 DOI: 10.1128/jvi.02264-13] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The P9-1 protein of Rice black-streaked dwarf virus (RBSDV) is an essential part of the viroplasm. However, little is known about its nature or biological function in the viroplasm. In this study, the structure and function of P9-1 were analyzed for in vitro binding to nucleic acids. We found that the P9-1 protein preferentially bound to single-stranded versus double-stranded nucleic acids; however, the protein displayed no preference for RBSDV versus non-RBSDV single-stranded ssRNA (ssRNA). A gel mobility shift assay revealed that the RNA gradually shifted as increasing amounts of P9-1 were added, suggesting that multiple subunits of P9-1 bind to ssRNA. By using discontinuous blue native gel and chromatography analysis, we found that the P9-1 protein was capable of forming dimers, tetramers, and octamers. Strikingly, we demonstrated that P9-1 preferentially bound to ssRNA in the octamer, rather than the dimer, form. Deletion of the C-terminal arm resulted in P9-1 no longer forming octamers; consequently, the deletion mutant protein bound to ssRNA with significantly lower affinity and with fewer copies bound per ssRNA. Alanine substitution analysis revealed that electropositive amino acids among residues 25 to 44 are important for RNA binding and map to the central interior structure that was formed only by P9-1 octamers. Collectively, our findings provide novel insights into the structure and function of RBSDV viroplasm protein P9-1 binding to RNA.
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Autophagy hijacked through viroporin-activated calcium/calmodulin-dependent kinase kinase-β signaling is required for rotavirus replication. Proc Natl Acad Sci U S A 2012. [PMID: 23184977 DOI: 10.1073/pnas.1216539109] [Citation(s) in RCA: 121] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Autophagy is a cellular degradation process involving an intracellular membrane trafficking pathway that recycles cellular components or eliminates intracellular microbes in lysosomes. Many pathogens subvert autophagy to enhance their replication, but the mechanisms these pathogens use to initiate the autophagy process have not been elucidated. This study identifies rotavirus as a pathogen that encodes a viroporin, nonstructural protein 4, which releases endoplasmic reticulum calcium into the cytoplasm, thereby activating a calcium/calmodulin-dependent kinase kinase-β and 5' adenosine monophosphate-activated protein kinase-dependent signaling pathway to initiate autophagy. Rotavirus hijacks this membrane trafficking pathway to transport viral proteins from the endoplasmic reticulum to sites of viral replication to produce infectious virus. This process requires PI3K activity and autophagy-initiation proteins Atg3 and Atg5, and it is abrogated by chelating cytoplasmic calcium or inhibiting calcium/calmodulin-dependent kinase kinase-β. Although the early stages of autophagy are initiated, rotavirus infection also blocks autophagy maturation. These studies identify a unique mechanism of virus-mediated, calcium-activated signaling that initiates autophagy and hijacks this membrane trafficking pathway to transport viral proteins to sites of viral assembly.
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Crystallographic Analysis of Rotavirus NSP2-RNA Complex Reveals Specific Recognition of 5' GG Sequence for RTPase Activity. J Virol 2012; 86:10547-57. [PMID: 22811529 PMCID: PMC3457270 DOI: 10.1128/jvi.01201-12] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Rotavirus nonstructural protein NSP2, a functional octamer, is critical for the formation of viroplasms, which are exclusive sites for replication and packaging of the segmented double-stranded RNA (dsRNA) rotavirus genome. As a component of replication intermediates, NSP2 is also implicated in various replication-related activities. In addition to sequence-independent single-stranded RNA-binding and helix-destabilizing activities, NSP2 exhibits monomer-associated nucleoside and 5' RNA triphosphatase (NTPase/RTPase) activities that are mediated by a conserved H225 residue within a narrow enzymatic cleft. Lack of a 5' γ-phosphate is a common feature of the negative-strand RNA [(-)RNA] of the packaged dsRNA segments in rotavirus. Strikingly, all (-)RNAs (of group A rotaviruses) have a 5' GG dinucleotide sequence. As the only rotavirus protein with 5' RTPase activity, NSP2 is implicated in the removal of the γ-phosphate from the rotavirus (-)RNA. To understand how NSP2, despite its sequence-independent RNA-binding property, recognizes (-)RNA to hydrolyze the γ-phosphate within the catalytic cleft, we determined a crystal structure of NSP2 in complex with the 5' consensus sequence of minus-strand rotavirus RNA. Our studies show that the 5' GG of the bound oligoribonucleotide interacts extensively with highly conserved residues in the NSP2 enzymatic cleft. Although these residues provide GG-specific interactions, surface plasmon resonance studies suggest that the C-terminal helix and other basic residues outside the enzymatic cleft account for sequence-independent RNA binding of NSP2. A novel observation from our studies, which may have implications in viroplasm formation, is that the C-terminal helix of NSP2 exhibits two distinct conformations and engages in domain-swapping interactions, which result in the formation of NSP2 octamer chains.
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Bucardo F, Rippinger CM, Svensson L, Patton JT. Vaccine-derived NSP2 segment in rotaviruses from vaccinated children with gastroenteritis in Nicaragua. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2012; 12:1282-94. [PMID: 22487061 PMCID: PMC3372771 DOI: 10.1016/j.meegid.2012.03.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2012] [Revised: 03/09/2012] [Accepted: 03/10/2012] [Indexed: 10/28/2022]
Abstract
Rotavirus (RV) vaccination programs have been established in several countries using the human-attenuated G1P[8] monovalent vaccine Rotarix (GlaxoSmithKline) and/or the human-bovine reassortant G1, G2, G3, G4, P[8] pentavalent vaccine RotaTeq (Merck). The efficacy of both vaccines is high (∼90%) in developed countries, but can be remarkably lower in developing countries. For example, a vaccine efficacy against severe diarrhea of only 58% was observed in a 2007-2009 Nicaraguan study using RotaTeq. To gain insight into the significant level of vaccine failure in this country, we sequenced the genomes of RVs recovered from vaccinated Nicaraguan children with gastroenteritis. The results revealed that all had genotype specificities typical for human RVs (11 G1P[8], 1 G3P[8]) and that the sequences and antigenic epitopes of the outer capsid proteins (VP4 and VP7) of these viruses were similar to those reported for RVs isolated elsewhere in the world. As expected, nine of the G1P[8] viruses and the single G3P[8] virus had genome constellations typical of human G1P[8] and G3P[8] RVs: G1/3-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1. However, two of the G1P[8] viruses had atypical constellations, G1-P[8]-I1-R1-C1-M1-A1-N2-T1-E1-H1, due to the presence of a genotype-2 NSP2 (N2) gene. The sequence of the N2 NSP2 gene was identical to the bovine N2 NSP2 gene of RotaTeq, indicating that the two atypical viruses originated via reassortment of human G1P[8] RVs with RotaTeq viruses. Together, our data suggest that the high level of vaccine failure in Nicaraguan is probably not due to antigenic drift of commonly circulating virus strains nor the emergence of new antigenetically distinct virus strains. Furthermore, our data suggest that the widespread use of the RotaTeq vaccine has led to the introduction of vaccine genes into circulating human RVs.
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Affiliation(s)
- Filemón Bucardo
- Department of Microbiology, University of León, UNAN-León, Nicaragua
| | - Christine M. Rippinger
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Lennart Svensson
- Division of Molecular Virology, Department of Clinical and Experimental Medicine, Linköping University, Sweden
| | - John T. Patton
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
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Jia D, Guo N, Chen H, Akita F, Xie L, Omura T, Wei T. Assembly of the viroplasm by viral non-structural protein Pns10 is essential for persistent infection of rice ragged stunt virus in its insect vector. J Gen Virol 2012; 93:2299-2309. [PMID: 22837415 DOI: 10.1099/vir.0.042424-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Rice ragged stunt virus (RRSV), an oryzavirus, is transmitted by brown planthopper in a persistent propagative manner. In this study, sequential infection of RRSV in the internal organs of its insect vector after ingestion of virus was investigated by immunofluorescence microscopy. RRSV was first detected in the epithelial cells of the midgut, from where it proceeded to the visceral muscles surrounding the midgut, then throughout the visceral muscles of the midgut and hindgut, and finally into the salivary glands. Viroplasms, the sites of virus replication and assembly of progeny virions, were formed in the midgut epithelium, visceral muscles and salivary glands of infected insects and contained the non-structural protein Pns10 of RRSV, which appeared to be the major constituent of the viroplasms. Viroplasm-like structures formed in non-host insect cells following expression of Pns10 in a baculovirus system, suggesting that the viroplasms observed in RRSV-infected cells were composed basically of Pns10. RNA interference induced by ingestion of dsRNA from the Pns10 gene of RRSV strongly inhibited such viroplasm formation, preventing efficient virus infection and spread in its insect vectors. These results show that Pns10 of RRSV is essential for viroplasm formation and virus replication in the vector insect.
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Affiliation(s)
- Dongsheng Jia
- Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, PR China
| | - Nianmei Guo
- Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, PR China
| | - Hongyan Chen
- Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, PR China
| | - Fusamichi Akita
- National Agricultural Research Center, 3-1-1 Kannondai, Tsukuba, Ibaraki 305-8666, Japan
| | - Lianhui Xie
- Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, PR China
| | - Toshihiro Omura
- National Agricultural Research Center, 3-1-1 Kannondai, Tsukuba, Ibaraki 305-8666, Japan
| | - Taiyun Wei
- Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, PR China
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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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Diversity and relationships of cocirculating modern human rotaviruses revealed using large-scale comparative genomics. J Virol 2012; 86:9148-62. [PMID: 22696651 DOI: 10.1128/jvi.01105-12] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Group A rotaviruses (RVs) are 11-segmented, double-stranded RNA viruses and are primary causes of gastroenteritis in young children. Despite their medical relevance, the genetic diversity of modern human RVs is poorly understood, and the impact of vaccine use on circulating strains remains unknown. In this study, we report the complete genome sequence analysis of 58 RVs isolated from children with severe diarrhea and/or vomiting at Vanderbilt University Medical Center (VUMC) in Nashville, TN, during the years spanning community vaccine implementation (2005 to 2009). The RVs analyzed include 36 G1P[8], 18 G3P[8], and 4 G12P[8] Wa-like genogroup 1 strains with VP6-VP1-VP2-VP3-NSP1-NSP2-NSP3-NSP4-NSP5/6 genotype constellations of I1-R1-C1-M1-A1-N1-T1-E1-H1. By constructing phylogenetic trees, we identified 2 to 5 subgenotype alleles for each gene. The results show evidence of intragenogroup gene reassortment among the cocirculating strains. However, several isolates from different seasons maintained identical allele constellations, consistent with the notion that certain RV clades persisted in the community. By comparing the genes of VUMC RVs to those of other archival and contemporary RV strains for which sequences are available, we defined phylogenetic lineages and verified that the diversity of the strains analyzed in this study reflects that seen in other regions of the world. Importantly, the VP4 and VP7 proteins encoded by VUMC RVs and other contemporary strains show amino acid changes in or near neutralization domains, which might reflect antigenic drift of the virus. Thus, this large-scale, comparative genomic study of modern human RVs provides significant insight into how this pathogen evolves during its spread in the community.
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Selection and evolutionary analysis in the nonstructural protein NSP2 of rotavirus A. INFECTION GENETICS AND EVOLUTION 2012; 12:1355-61. [PMID: 22610044 DOI: 10.1016/j.meegid.2012.05.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 05/07/2012] [Accepted: 05/09/2012] [Indexed: 01/03/2023]
Abstract
Rotavirus A is the leading cause of acute gastroenteritis in infants and young children worldwide. The nonstructural protein 2 (NSP2) plays essential roles in the replication cycle of rotavirus and may play a role in protective immunity against rotavirus disease. Using a Bayesian approach, we measured the mutation rate of genotype N1 NSP2 gene sequences. The N1 genotype is the main NSP2 genotype associated with rotavirus strains causing severe disease, and was found to have a high mutation rate (8.7 × 10(-4) substitutions/site/year) in comparison to the rotavirus VP4 gene and rates of mutation in other RNA viruses. NSP2 has traditionally been considered as a conserved rotavirus protein and selection analysis indicated that the NSP2 protein was under strong negative selection, suggesting that most nucleotide substitutions were synonymous. This conservation is likely a result of functional constraints of NSP2 in the rotavirus replication cycle. Four sites of positive selection were identified; two of these (positions 249 and 255) were located in a previously characterised antibody binding epitope. The remaining sites were not located in known functional regions, and the reason for variation at these sites remains to be elucidated.
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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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Crystallographic analysis reveals octamerization of viroplasm matrix protein P9-1 of Rice black streaked dwarf virus. J Virol 2011; 86:746-56. [PMID: 22072761 DOI: 10.1128/jvi.00826-11] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The P9-1 protein of Rice black streaked dwarf virus accumulates in viroplasm inclusions, which are structures that appear to play an important role in viral morphogenesis and are commonly found in viruses in the family Reoviridae. Crystallographic analysis of P9-1 revealed structural features that allow the protein to form dimers via hydrophobic interactions. Each dimer has carboxy-terminal regions, resembling arms, that extend to neighboring dimers, thereby uniting sets of four dimers via lateral hydrophobic interactions, to yield cylindrical octamers. The importance of these regions for the formation of viroplasm-like inclusions was confirmed by the absence of such inclusions when P9-1 was expressed without its carboxy-terminal arm. The octamers are vertically elongated cylinders resembling the structures formed by NSP2 of rotavirus, even though there are no significant similarities between the respective primary and secondary structures of the two proteins. Our results suggest that an octameric structure with an internal pore might be important for the functioning of the respective proteins in the events that occur in the viroplasm, which might include viral morphogenesis.
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Akita F, Miyazaki N, Hibino H, Shimizu T, Higashiura A, Uehara-Ichiki T, Sasaya T, Tsukihara T, Nakagawa A, Iwasaki K, Omura T. Viroplasm matrix protein Pns9 from rice gall dwarf virus forms an octameric cylindrical structure. J Gen Virol 2011; 92:2214-2221. [DOI: 10.1099/vir.0.032524-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The non-structural Pns9 protein of rice gall dwarf virus (RGDV) accumulates in viroplasm inclusions, which are structures that appear to play an important role in viral morphogenesis and are commonly found in host cells infected by viruses in the family Reoviridae. Immunofluorescence and immunoelectron microscopy of RGDV-infected vector cells in monolayers, using antibodies against Pns9 of RGDV and expression of Pns9 in Spodoptera frugiperda cells, demonstrated that Pns9 is the minimal viral factor necessary for formation of viroplasm inclusion during infection by RGDV. When Pns9 in solution was observed under a conventional electron microscope, it appeared as ring-like aggregates of approximately 100 Å in diameter. Cryo-electron microscopic analysis of these aggregates revealed cylinders of octameric Pns9, whose dimensions were similar to those observed under the conventional electron microscope. Octamerization of Pns9 in solution was confirmed by the results of size-exclusion chromatography. Among proteins of viruses that belong to the family Reoviridae whose three-dimensional structures are available, a matrix protein of the viroplasm of rotavirus, NSP2, forms similar octamers, an observation that suggests similar roles for Pns9 and NSP2 in morphogenesis in animal-infecting and in plant-infecting reoviruses.
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Affiliation(s)
- Fusamichi Akita
- National Agricultural Research Center, 3-1-1 Kan-nondai, Tsukuba, Ibaraki 305-8666, Japan
| | - Naoyuki Miyazaki
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Hiroyuki Hibino
- National Agricultural Research Center, 3-1-1 Kan-nondai, Tsukuba, Ibaraki 305-8666, Japan
| | - Takumi Shimizu
- National Agricultural Research Center, 3-1-1 Kan-nondai, Tsukuba, Ibaraki 305-8666, Japan
| | - Akifumi Higashiura
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Tamaki Uehara-Ichiki
- National Agricultural Research Center, 3-1-1 Kan-nondai, Tsukuba, Ibaraki 305-8666, Japan
| | - Takahide Sasaya
- National Agricultural Research Center, 3-1-1 Kan-nondai, Tsukuba, Ibaraki 305-8666, Japan
| | - Tomitake Tsukihara
- Department of Life Science, University of Hyogo, 3-2-1 Koto, Kamighori, Akoh, Hyogo 678-1297, Japan
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Atsushi Nakagawa
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Kenji Iwasaki
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Toshihiro Omura
- National Agricultural Research Center, 3-1-1 Kan-nondai, Tsukuba, Ibaraki 305-8666, Japan
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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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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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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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39
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Wang Q, Tao T, Zhang Y, Wu W, Li D, Yu J, Han C. Rice black-streaked dwarf virus P6 self-interacts to form punctate, viroplasm-like structures in the cytoplasm and recruits viroplasm-associated protein P9-1. Virol J 2011; 8:24. [PMID: 21241517 PMCID: PMC3032713 DOI: 10.1186/1743-422x-8-24] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Accepted: 01/18/2011] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND Rice black-streaked dwarf virus (RBSDV), a member of the genus Fijivirus within the family Reoviridae, can infect several graminaceous plant species including rice, maize and wheat, and is transmitted by planthoppers. Although several RBSDV proteins have been studied in detail, functions of the nonstructural protein P6 are still largely unknown. RESULTS In the current study, we employed yeast two-hybrid assays, bimolecular fluorescence complementation and subcellular localization experiments to show that P6 can self-interact to form punctate, cytoplasmic viroplasm-like structures (VLS) when expressed alone in plant cells. The region from residues 395 to 659 is necessary for P6 self-interaction, whereas two polypeptides (residues 580-620 and 615-655) are involved in the subcellular localization of P6. Furthermore, P6 strongly interacts with the viroplasm-associated protein P9-1 and recruits P9-1 to localize in VLS. The P6 395-659 region is also important for the P6-P9-1 interaction, and deleting any region of P9-1 abolishes this heterologous interaction. CONCLUSIONS RBSDV P6 protein has an intrinsic ability to self-interact and forms VLS without other RBSDV proteins or RNAs. P6 recruits P9-1 to VLS by direct protein-protein interaction. This is the first report on the functionality of RBSDV P6 protein. P6 may be involved in the process of viroplasm nucleation and virus morphogenesis.
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Affiliation(s)
- Qian Wang
- State Key Laboratory for Agro-biotechnology and Ministry of Agriculture Key Laboratory for Plant Pathology, China Agricultural University, Beijing 100193, P. R. China
| | - Tao Tao
- State Key Laboratory for Agro-biotechnology and Ministry of Agriculture Key Laboratory for Plant Pathology, China Agricultural University, Beijing 100193, P. R. China
| | - Yanjing Zhang
- State Key Laboratory for Agro-biotechnology and Ministry of Agriculture Key Laboratory for Plant Pathology, China Agricultural University, Beijing 100193, P. R. China
| | - Wenqi Wu
- State Key Laboratory for Agro-biotechnology and Ministry of Agriculture Key Laboratory for Plant Pathology, China Agricultural University, Beijing 100193, P. R. China
| | - Dawei Li
- State Key Laboratory for Agro-biotechnology and Ministry of Agriculture Key Laboratory for Plant Pathology, China Agricultural University, Beijing 100193, P. R. China
| | - Jialin Yu
- State Key Laboratory for Agro-biotechnology and Ministry of Agriculture Key Laboratory for Plant Pathology, China Agricultural University, Beijing 100193, P. R. China
| | - Chenggui Han
- State Key Laboratory for Agro-biotechnology and Ministry of Agriculture Key Laboratory for Plant Pathology, China Agricultural University, Beijing 100193, P. R. China
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Dual selection mechanisms drive efficient single-gene reverse genetics for rotavirus. Proc Natl Acad Sci U S A 2010; 107:18652-7. [PMID: 20937889 DOI: 10.1073/pnas.1011948107] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Current methods for engineering the segmented double-stranded RNA genome of rotavirus (RV) are limited by inefficient recovery of the recombinant virus. In an effort to expand the utility of RV reverse genetics, we developed a method to recover recombinant viruses in which independent selection strategies are used to engineer single-gene replacements. We coupled a mutant SA11 RV encoding a temperature-sensitive (ts) defect in the NSP2 protein with RNAi-mediated degradation of NSP2 mRNAs to isolate a virus containing a single recombinant gene that evades both selection mechanisms. Recovery is rapid and simple; after two rounds of selective passage the recombinant virus reaches titers of ≥10(4) pfu/mL. We used this reverse genetics method to generate a panel of viruses with chimeric NSP2 genes. For one of the chimeric viruses, the introduced NSP2 sequence was obtained from a pathogenic, noncultivated human RV isolate, demonstrating that this reverse genetics system can be used to study the molecular biology of circulating RVs. Combining characterized RV ts mutants and validated siRNA targets should permit the extension of this "two-hit" reverse genetics methodology to other RV genes. Furthermore, application of a dual selection strategy to previously reported reverse genetics methods for RV may enhance the efficiency of recombinant virus recovery.
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Butan C, Tucker P. Insights into the role of the non-structural protein 2 (NS2) in Bluetongue virus morphogenesis. Virus Res 2010; 151:109-17. [DOI: 10.1016/j.virusres.2010.05.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2010] [Revised: 05/25/2010] [Accepted: 05/27/2010] [Indexed: 10/19/2022]
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X-ray crystal structure of the rotavirus inner capsid particle at 3.8 A resolution. J Mol Biol 2010; 397:587-99. [PMID: 20122940 DOI: 10.1016/j.jmb.2010.01.055] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Revised: 01/19/2010] [Accepted: 01/22/2010] [Indexed: 12/15/2022]
Abstract
The rotavirus inner capsid particle, known as the "double-layered particle" (DLP), is the "payload" delivered into a cell in the process of viral infection. Its inner and outer protein layers, composed of viral protein (VP) 2 and VP6, respectively, package the 11 segments of the double-stranded RNA (dsRNA) of the viral genome, as well as about the same number of polymerase molecules (VP1) and capping-enzyme molecules (VP3). We have determined the crystal structure of the bovine rotavirus DLP. There is one full particle (outer diameter approximately 700 A) in the asymmetric unit of the P2(1)2(1)2(1) unit cell of dimensions a=740 A, b=1198 A, and c=1345 A. A three-dimensional reconstruction from electron cryomicroscopy was used as a molecular replacement model for initial phase determination to about 18.5 A resolution, and the 60-fold redundancy of icosahedral particle symmetry allowed phases to be extended stepwise to the limiting resolution of the data (3.8 A). The structure of a VP6 trimer (determined previously by others) fits the outer layer density with very little adjustment. The T=13 triangulation number of that layer implies that there are four and one-third VP6 trimers per icosahedral asymmetric unit. The inner layer has 120 copies of VP2 and thus 2 copies per icosahedral asymmetric unit, designated VP2A and VP2B. Residues 101-880 fold into a relatively thin principal domain, comma-like in outline, shaped such that only rather modest distortions (concentrated at two "subdomain" boundaries) allow VP2A and VP2B to form a uniform layer with essentially no gaps at the subunit boundaries, except for a modest pore along the 5-fold axis. The VP2 principal domain resembles those of the corresponding shells and homologous proteins in other dsRNA viruses: lambda1 in orthoreoviruses and VP3 in orbiviruses. Residues 1-80 of VP2A and VP2B fold together with four other such pairs into a "5-fold hub" that projects into the DLP interior along the 5-fold axis; residues 81-100 link the 10 polypeptide chains emerging from a 5-fold hub to the N-termini of their corresponding principal domains, clustered into a decameric assembly unit. The 5-fold hub appears to have several distinct functions. One function is to recruit a copy of VP1 (or of a VP1-VP3 complex), potentially along with a segment of plus-strand RNA, as a decamer of VP2 assembles. The second function is to serve as a shaft around which can coil a segment of dsRNA. The third function is to guide nascent mRNA, synthesized in the DLP interior by VP1 and 5'-capped by the action of VP3, out through a 5-fold exit channel. We propose a model for rotavirus particle assembly, based on known requirements for virion formation, together with the structure of the DLP and that of VP1, determined earlier.
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Analysis of rotavirus non-structural protein NSP5 by mass spectrometry reveals a complex phosphorylation pattern. Virus Res 2009; 149:104-8. [PMID: 20036292 DOI: 10.1016/j.virusres.2009.12.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2009] [Revised: 12/12/2009] [Accepted: 12/17/2009] [Indexed: 01/23/2023]
Abstract
Genomic replication and partial assembly of Rotavirus takes place in cytoplasmic viral structures called viroplasms. NSP5 is a viral phosphoprotein localized in viroplasms and its expression is imperative for viral cycle progress. During infection three isoforms of NSP5 can be observed by SDS-PAGE (26, 28 and 33-35kDa) and previous reports suggested that they differ in their phosphorylation patterns. In this study we obtained NSP5 from infected cells and by mass spectrometry we were able to identify nine phosphorylation sites. We detected that in all the isoforms the same residues can be found either phosphorylated or unmodified. Quantitative analysis showed that the 28kDa isoform has a higher phosphorylation level than the 26kDa isoform suggesting that migration properties depend on the total number of phosphorylated residues. Moreover, we identified two not previously described modifications for this protein: an N-acetylation in Serine-2 and an intramolecular disulfide bond in a highly conserved motif, CXXC which is located between two charged alpha-helix motifs.
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44
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Sequestration of free tubulin molecules by the viral protein NSP2 induces microtubule depolymerization during rotavirus infection. J Virol 2009; 84:2522-32. [PMID: 20032187 DOI: 10.1128/jvi.01883-09] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Microtubules, components of the cell cytoskeleton, play a central role in cellular trafficking. Here we show that rotavirus infection leads to a remodeling of the microtubule network together with the formation of tubulin granules. While most microtubules surrounding the nucleus depolymerize, others appear packed at the cell periphery. In microtubule depolymerization areas, tubulin granules are observed; they colocalize with viroplasms, viral compartments formed by interactions between rotavirus proteins NSP2 and NSP5. With purified proteins, we show that tubulin directly interacts in vitro with NSP2 but not with NSP5. The binding of NSP2 to tubulin is independent of its phosphatase activity. The comparison of three-dimensional (3-D) reconstructions of NSP2 octamers alone or associated with tubulin reveals electron densities in the positively charged grooves of NSP2 that we attribute to tubulin. Site-directed mutagenesis of NSP2 and competition assays between RNA and tubulin for NSP2 binding confirm that tubulin binds to these charged grooves of NSP2. Although the tubulin position within NSP2 grooves cannot be precisely determined, the tubulin C-terminal H12 alpha-helix could be involved in the interaction. NSP2 overexpression and rotavirus infection produce similar effects on the microtubule network. NSP2 depolymerizes microtubules and leads to tubulin granule formation. Our results demonstrate that tubulin is a viroplasm component and reveal an original mechanism. Tubulin sequestration by NSP2 induces microtubule depolymerization. This depolymerization probably reroutes the cell machinery by inhibiting trafficking and functions potentially involved in defenses to viral infections.
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45
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Rotavirus strategies to evade host antiviral innate immunity. Immunol Lett 2009; 127:13-8. [DOI: 10.1016/j.imlet.2009.08.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2009] [Revised: 08/14/2009] [Accepted: 08/18/2009] [Indexed: 01/18/2023]
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46
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Desselberger U. Towards achieving a high-resolution structure of rotavirus particles. Future Virol 2009. [DOI: 10.2217/fvl.09.50] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Evaluation of: Aoki ST, Settembre EC, Trask SD, Greenberg HB, Harrison SC, Dormitzer PR: Structure of rotavirus outer-layer protein VP7 bound with a neutralizing Fab. Science 324 (5993), 1444–1447 (2009). The determination of the molecular structure of the trimer of VP7, one of the outer layer proteins of rotaviruses, has significantly contributed to the knowledge of the overall structure of rotavirus particles. The molecular mechanism of rotavirus neutralization has been clarified and a topological explanation been found for the emergence of antibody escape mutants. Furthermore, translational work was enabled by engineering VP7 mutants, which form stable trimers by means of novel disulfide bridges linking the different subunits together; such a construct could become an attractive and safe vaccine candidate.
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Affiliation(s)
- Ulrich Desselberger
- University of Cambridge, Department of Medicine, Addenbrooke’s Hospital, Cambridge, CB2 0QQ, UK
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47
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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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48
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Nagashima S, Kobayashi N, Ishino M, Alam MM, Ahmed MU, Paul SK, Ganesh B, Chawla-Sarkar M, Krishnan T, Naik TN, Wang YH. Whole genomic characterization of a human rotavirus strain B219 belonging to a novel group of the genus rotavirus. J Med Virol 2008; 80:2023-33. [DOI: 10.1002/jmv.21286] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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49
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Marsh MP, Chang JT, Booth CR, Liang NL, Schmid MF, Chiu W. Modular software platform for low-dose electron microscopy and tomography. J Microsc 2007; 228:384-9. [PMID: 18045333 PMCID: PMC4384816 DOI: 10.1111/j.1365-2818.2007.01856.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Transmission electron microscopy imaging protocols required by structural scientists vary widely and can be laborious without tailor-made applications. We present here the jeol automated microscopy expert system (james) api integrator, a programming library for computer control of transmission electron microscopy operations and equipment. james has been implemented on JEOL microscopes with Gatan CCDs but is designed to be modular so it can be adapted to run on different microscopes and detectors. We have used the james api integrator to develop two applications for low-dose digital imaging: james imaging application and the mr t tomographic imaging application. Both applications have been widely used within our NCRR-supported Center for routine data collection and are now made available for public download.
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Affiliation(s)
- Michael P Marsh
- Graduate Program in Structural and Computational Biology and Molecular Biophysics, and National Center for Macromolecular Imaging, #Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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50
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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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