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Kotaki T, Kanai Y, Onishi M, Minami S, Chen Z, Nouda R, Nurdin JA, Yamasaki M, Kobayashi T. Generation of single-round infectious rotavirus with a mutation in the intermediate capsid protein VP6. J Virol 2024:e0076224. [PMID: 38837379 DOI: 10.1128/jvi.00762-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Accepted: 05/02/2024] [Indexed: 06/07/2024] Open
Abstract
Rotavirus causes severe diarrhea in infants. Although live attenuated rotavirus vaccines are available, vaccine-derived infections have been reported, which warrants development of next-generation rotavirus vaccines. A single-round infectious virus is a promising vaccine platform; however, this platform has not been studied extensively in the context of rotavirus. Here, we aimed to develop a single-round infectious rotavirus by impairing the function of the viral intermediate capsid protein VP6. Recombinant rotaviruses harboring mutations in VP6 were rescued using a reverse genetics system. Mutations were targeted at VP6 residues involved in virion assembly. Although the VP6-mutated rotavirus expressed viral proteins, it did not produce progeny virions in wild-type cells; however, the virus did produce progeny virions in VP6-expressing cells. This indicates that the VP6-mutated rotavirus is a single-round infectious rotavirus. Insertion of a foreign gene, and replacement of the VP7 gene segment with that of human rotavirus clinical isolates, was successful. No infectious virions were detected in mice infected with the single-round infectious rotavirus. Immunizing mice with the single-round infectious rotavirus induced neutralizing antibody titers as high as those induced by wild-type rotavirus. Taken together, the data suggest that this single-round infectious rotavirus has potential as a safe and effective rotavirus vaccine. This system is also applicable for generation of safe and orally administrable viral vectors.IMPORTANCERotavirus, a leading cause of acute gastroenteritis in infants, causes an annual estimated 128,500 infant deaths worldwide. Although live attenuated rotavirus vaccines are available, they are replicable and may cause vaccine-derived infections. Thus, development of safe and effective rotavirus vaccine is important. In this study, we report the development of a single-round infectious rotavirus that can replicate only in cells expressing viral VP6 protein. We demonstrated that (1) the single-round infectious rotavirus did not replicate in wild-type cells or in mice; (2) insertion of foreign genes and replacement of the outer capsid gene were possible; and (3) it was as immunogenic as the wild-type virus. Thus, the mutated virus shows promise as a next-generation rotavirus vaccine. The system is also applicable to orally administrable viral vectors, facilitating development of vaccines against other enteric pathogens.
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Affiliation(s)
- Tomohiro Kotaki
- Department of Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Yuta Kanai
- Department of Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Megumi Onishi
- Department of Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Shohei Minami
- Department of Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Zelin Chen
- Department of Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Ryotaro Nouda
- Department of Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Jeffery A Nurdin
- Department of Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Moeko Yamasaki
- Department of Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Takeshi Kobayashi
- Department of Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
- Center for Infectious Disease Education and Research, Osaka University, Osaka, Japan
- Center for Advanced Modalities and DDS, Osaka University, Osaka, Japan
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2
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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 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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3
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Anderson ML, Sullivan OM, Nichols SL, Kaylor L, Kelly DF, McDonald Esstman S. Rotavirus core shell protein sites that regulate intra-particle polymerase activity. J Virol 2023; 97:e0086023. [PMID: 37830817 PMCID: PMC10617381 DOI: 10.1128/jvi.00860-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 09/06/2023] [Indexed: 10/14/2023] Open
Abstract
IMPORTANCE Rotaviruses are important causes of severe gastroenteritis in young children. A characteristic feature of rotaviruses is that they copy ribonucleic acid (RNA) inside of the viral particle. In fact, the viral polymerase (VP1) only functions when it is connected to the viral inner core shell protein (VP2). Here, we employed a biochemical assay to identify which sites of VP2 are critical for regulating VP1 activity. Specifically, we engineered VP2 proteins to contain amino acid changes at structurally defined sites and assayed them for their capacity to support VP1 function in a test tube. Through this work, we were able to identify several VP2 residues that appeared to regulate the activity of the polymerase, positively and negatively. These results are important because they help explain how rotavirus synthesizes its RNA while inside of particles and they identify targets for the future rational design of drugs to prevent rotavirus disease.
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Affiliation(s)
| | - Owen M. Sullivan
- Department of Biology, Wake Forest University, Winston-Salem, North Carolina, USA
| | - Sarah L. Nichols
- Department of Biology, Wake Forest University, Winston-Salem, North Carolina, USA
| | - Liam Kaylor
- Department of Biomedical Engineering, State University, University Park, Pennsylvania, USA
| | - Deborah F. Kelly
- Department of Biomedical Engineering, State University, University Park, Pennsylvania, USA
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4
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Asensio-Cob D, Rodríguez JM, Luque D. Rotavirus Particle Disassembly and Assembly In Vivo and In Vitro. Viruses 2023; 15:1750. [PMID: 37632092 PMCID: PMC10458742 DOI: 10.3390/v15081750] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 08/11/2023] [Accepted: 08/14/2023] [Indexed: 08/27/2023] Open
Abstract
Rotaviruses (RVs) are non-enveloped multilayered dsRNA viruses that are major etiologic agents of diarrheal disease in humans and in the young in a large number of animal species. The viral particle is composed of three different protein layers that enclose the segmented dsRNA genome and the transcriptional complexes. Each layer defines a unique subparticle that is associated with a different phase of the replication cycle. Thus, while single- and double-layered particles are associated with the intracellular processes of selective packaging, genome replication, and transcription, the viral machinery necessary for entry is located in the third layer. This modular nature of its particle allows rotaviruses to control its replication cycle by the disassembly and assembly of its structural proteins. In this review, we examine the significant advances in structural, molecular, and cellular RV biology that have contributed during the last few years to illuminating the intricate details of the RV particle disassembly and assembly processes.
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Affiliation(s)
- Dunia Asensio-Cob
- Department of Molecular Medicine, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G0A4, Canada;
| | - Javier M. Rodríguez
- Department of Structure of Macromolecules, Centro Nacional de Biotecnología/CSIC, Cantoblanco, 28049 Madrid, Spain
| | - Daniel Luque
- Electron Microscopy Unit UCCT/ISCIII, 28220 Majadahonda, Spain
- School of Biomedical Sciences, The University of New South Wales, Sydney, NSW 2052, Australia
- Electron Microscope Unit, Mark Wainwright Analytical Centre, The University of New South Wales, Sydney, NSW 2052, Australia
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5
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Zhang Q, Gao Y, Baker ML, Liu S, Jia X, Xu H, He J, Kaelber JT, Weng S, Jiang W. The structure of a 12-segmented dsRNA reovirus: New insights into capsid stabilization and organization. PLoS Pathog 2023; 19:e1011341. [PMID: 37083840 PMCID: PMC10155992 DOI: 10.1371/journal.ppat.1011341] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 05/03/2023] [Accepted: 04/02/2023] [Indexed: 04/22/2023] Open
Abstract
Infecting a wide range of hosts, members of Reovirales (formerly Reoviridae) consist of a genome with different numbers of segmented double stranded RNAs (dsRNA) encapsulated by a proteinaceous shell and carry out genome replication and transcription inside the virion. Several cryo-electron microscopy (cryo-EM) structures of reoviruses with 9, 10 or 11 segmented dsRNA genomes have revealed insights into genome arrangement and transcription. However, the structure and genome arrangement of 12-segmented Reovirales members remain poorly understood. Using cryo-EM, we determined the structure of mud crab reovirus (MCRV), a 12-segmented dsRNA virus that is a putative member of Reovirales in the non-turreted Sedoreoviridae family, to near-atomic resolutions with icosahedral symmetry (3.1 Å) and without imposing icosahedral symmetry (3.4 Å). These structures revealed the organization of the major capsid proteins in two layers: an outer T = 13 layer consisting of VP12 trimers and unique VP11 clamps, and an inner T = 1 layer consisting of VP3 dimers. Additionally, ten RNA dependent RNA polymerases (RdRp) were well resolved just below the VP3 layer but were offset from the 5-fold axes and arranged with D5 symmetry, which has not previously been seen in other members of Reovirales. The N-termini of VP3 were shown to adopt four unique conformations; two of which anchor the RdRps, while the other two conformations are likely involved in genome organization and capsid stability. Taken together, these structures provide a new level of understanding for capsid stabilization and genome organization of segmented dsRNA viruses.
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Affiliation(s)
- Qinfen Zhang
- State key lab for biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Yuanzhu Gao
- State key lab for biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Matthew L Baker
- Department of Biochemistry and Molecular Biology, Structural Biology Imaging Center, McGovern Medical School at the University of Texas Health Science Center, Houston, Texas, United States of America
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Shanshan Liu
- State key lab for biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Xudong Jia
- State key lab for biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Haidong Xu
- State key lab for biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Jianguo He
- State key lab for biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Jason T Kaelber
- Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, New Jersey, United States of America
| | - Shaoping Weng
- State key lab for biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Wen Jiang
- Markey Center for Structural Biology, Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America
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6
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Anderson ML, McDonald Esstman S. In vitro particle-associated uridyltransferase activity of the rotavirus VP1 polymerase. Virology 2022; 577:24-31. [PMID: 36257129 PMCID: PMC10728782 DOI: 10.1016/j.virol.2022.09.015] [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: 08/29/2022] [Revised: 09/29/2022] [Accepted: 09/30/2022] [Indexed: 11/07/2022]
Abstract
Rotaviruses are 11-segmented, double-stranded RNA (dsRNA) viruses with a unique intra-particle RNA synthesis mechanism. During genome replication, the RNA-dependent RNA polymerase (VP1) performs minus-strand RNA (-ssRNA) synthesis on positive-strand RNA (+ssRNA) templates to create dsRNA segments. Recombinant VP1 catalyzes -ssRNA synthesis using substrate NTPs in vitro, but only when the VP2 core shell protein or virus-like particles made of VP2 and VP6 (2/6-VLPs) are included in the reaction. The dsRNA product can be labeled using [α32P]-UTP and separated from the input +ssRNA template by polyacrylamide gel electrophoresis. Here, we report the generation of [α32P]-labeled rotavirus +ssRNA templates in reactions that lacked non-radiolabeled NTPs but contained catalytically-active VP1, 2/6-VLPs, and [α32P]-UTP. Non-radiolabeled UTP competed with [α32P]-UTP to decrease product levels, whereas CTP and GTP had little effect. Interesting, ATP stimulated [α32P]-labeled product production. These results suggest that rotavirus VP1 transferred [α32P]-UMP onto viral + ssRNA in vitro via a particle-associated uridyltransferase activity.
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7
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Mwangi PN, Page NA, Seheri ML, Mphahlele MJ, Nadan S, Esona MD, Kumwenda B, Kamng'ona AW, Donato CM, Steele DA, Ndze VN, Dennis FE, Jere KC, Nyaga MM. Evolutionary changes between pre- and post-vaccine South African group A G2P[4] rotavirus strains, 2003-2017. Microb Genom 2022; 8. [PMID: 35446251 PMCID: PMC9453071 DOI: 10.1099/mgen.0.000809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The transient upsurge of G2P[4] group A rotavirus (RVA) after Rotarix vaccine introduction in several countries has been a matter of concern. To gain insight into the diversity and evolution of G2P[4] strains in South Africa pre- and post-RVA vaccination introduction, whole-genome sequencing was performed for RVA positive faecal specimens collected between 2003 and 2017 and samples previously sequenced were obtained from GenBank (n=103; 56 pre- and 47 post-vaccine). Pre-vaccine G2 sequences predominantly clustered within sub-lineage IVa-1. In contrast, post-vaccine G2 sequences clustered mainly within sub-lineage IVa-3, whereby a radical amino acid (AA) substitution, S15F, was observed between the two sub-lineages. Pre-vaccine P[4] sequences predominantly segregated within sub-lineage IVa while post-vaccine sequences clustered mostly within sub-lineage IVb, with a radical AA substitution R162G. Both S15F and R162G occurred outside recognised antigenic sites. The AA residue at position 15 is found within the signal sequence domain of Viral Protein 7 (VP7) involved in translocation of VP7 into endoplasmic reticulum during infection process. The 162 AA residue lies within the hemagglutination domain of Viral Protein 4 (VP4) engaged in interaction with sialic acid-containing structure during attachment to the target cell. Free energy change analysis on VP7 indicated accumulation of stable point mutations in both antigenic and non-antigenic regions. The segregation of South African G2P[4] strains into pre- and post-vaccination sub-lineages is likely due to erstwhile hypothesized stepwise lineage/sub-lineage evolution of G2P[4] strains rather than RVA vaccine introduction. Our findings reinforce the need for continuous whole-genome RVA surveillance and investigation of contribution of AA substitutions in understanding the dynamic G2P[4] epidemiology.
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Affiliation(s)
- Peter N Mwangi
- Next Generation Sequencing Unit and Division of Virology, Faculty of Health Sciences, University of the Free State, Bloemfontein 9300, South Africa
| | - Nicola A Page
- Centre for Enteric Disease, National Institute for Communicable Diseases, Private Bag X4, Sandringham, 2131, Johannesburg, South Africa.,Department of Medical Virology, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Arcadia, 0007, Pretoria, South Africa
| | - Mapaseka L Seheri
- Diarrheal Pathogens Research Unit, Sefako Makgatho Health Sciences University, Medunsa 0204, Pretoria, South Africa
| | - M Jeffrey Mphahlele
- Diarrheal Pathogens Research Unit, Sefako Makgatho Health Sciences University, Medunsa 0204, Pretoria, South Africa.,Office of the Deputy Vice Chancellor for Research and Innovation, North-West University, Potchefstroom 2351, South Africa.,South African Medical Research Council, Pretoria 0001, South Africa
| | - Sandrama Nadan
- Centre for Enteric Disease, National Institute for Communicable Diseases, Private Bag X4, Sandringham, 2131, Johannesburg, South Africa
| | - Mathew D Esona
- Diarrheal Pathogens Research Unit, Sefako Makgatho Health Sciences University, Medunsa 0204, Pretoria, South Africa
| | - Benjamin Kumwenda
- Department of Biomedical Sciences, School of Life Sciences and Applied Health Professions, Kamuzu University of Health Sciences, Private Bag 360, Chichiri, Blantyre 3, Malawi
| | - Arox W Kamng'ona
- Department of Biomedical Sciences, School of Life Sciences and Applied Health Professions, Kamuzu University of Health Sciences, Private Bag 360, Chichiri, Blantyre 3, Malawi
| | - Celeste M Donato
- Department of Medical Laboratory Sciences, School of Life Sciences and Applied Health Professions, Kamuzu University of Health Sciences, Private Bag 360, Chichiri, Blantyre3, Malawi.,Enteric Diseases Group, Murdoch Children's Research Institute, 50 Flemington Road, Parkville, Melboune 3052, Australia.,Department of Paediatrics, the University of Melbourne, Parkville 3010, Australia
| | - Duncan A Steele
- Diarrheal Pathogens Research Unit, Sefako Makgatho Health Sciences University, Medunsa 0204, Pretoria, South Africa
| | - Valantine N Ndze
- Faculty of Health Sciences, University of Buea, P.O Box 63 Buea, Cameroon
| | - Francis E Dennis
- Department of Electron Microscopy and Histopathology, Noguchi Memorial Institute for Medical Research, University of Ghana, P.O Box LG581, Legon, Ghana
| | - Khuzwayo C Jere
- Center for Global Vaccine Research, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, L697BE, Liverpool, UK.,Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre 312225, Malawi
| | - Martin M Nyaga
- Next Generation Sequencing Unit and Division of Virology, Faculty of Health Sciences, University of the Free State, Bloemfontein 9300, South Africa
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Caddy S, Papa G, Borodavka A, Desselberger U. Rotavirus research: 2014-2020. Virus Res 2021; 304:198499. [PMID: 34224769 DOI: 10.1016/j.virusres.2021.198499] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 06/24/2021] [Accepted: 06/25/2021] [Indexed: 02/09/2023]
Abstract
Rotaviruses are major causes of acute gastroenteritis in infants and young children worldwide and also cause disease in the young of many other mammalian and of avian species. During the recent 5-6 years rotavirus research has benefitted in a major way from the establishment of plasmid only-based reverse genetics systems, the creation of human and other mammalian intestinal enteroids, and from the wide application of structural biology (cryo-electron microscopy, cryo-EM tomography) and complementary biophysical approaches. All of these have permitted to gain new insights into structure-function relationships of rotaviruses and their interactions with the host. This review follows different stages of the viral replication cycle and summarizes highlights of structure-function studies of rotavirus-encoded proteins (both structural and non-structural), molecular mechanisms of viral replication including involvement of cellular proteins and lipids, the spectrum of viral genomic and antigenic diversity, progress in understanding of innate and acquired immune responses, and further developments of prevention of rotavirus-associated disease.
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Affiliation(s)
- Sarah Caddy
- Cambridge Institute for Therapeutic Immunology and Infectious Disease Jeffery Cheah Biomedical Centre, Cambridge, CB2 0AW, UK.
| | - Guido Papa
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus Francis Crick Avenue, Cambridge, CB2 0QH, UK.
| | - Alexander Borodavka
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK.
| | - Ulrich Desselberger
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK.
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9
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Papa G, Borodavka A, Desselberger U. Viroplasms: Assembly and Functions of Rotavirus Replication Factories. Viruses 2021; 13:1349. [PMID: 34372555 PMCID: PMC8310052 DOI: 10.3390/v13071349] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 07/08/2021] [Accepted: 07/09/2021] [Indexed: 02/07/2023] Open
Abstract
Viroplasms are cytoplasmic, membraneless structures assembled in rotavirus (RV)-infected cells, which are intricately involved in viral replication. Two virus-encoded, non-structural proteins, NSP2 and NSP5, are the main drivers of viroplasm formation. The structures (as far as is known) and functions of these proteins are described. Recent studies using plasmid-only-based reverse genetics have significantly contributed to elucidation of the crucial roles of these proteins in RV replication. Thus, it has been recognized that viroplasms resemble liquid-like protein-RNA condensates that may be formed via liquid-liquid phase separation (LLPS) of NSP2 and NSP5 at the early stages of infection. Interactions between the RNA chaperone NSP2 and the multivalent, intrinsically disordered protein NSP5 result in their condensation (protein droplet formation), which plays a central role in viroplasm assembly. These droplets may provide a unique molecular environment for the establishment of inter-molecular contacts between the RV (+)ssRNA transcripts, followed by their assortment and equimolar packaging. Future efforts to improve our understanding of RV replication and genome assortment in viroplasms should focus on their complex molecular composition, which changes dynamically throughout the RV replication cycle, to support distinct stages of virion assembly.
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Affiliation(s)
- Guido Papa
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK;
| | | | - Ulrich Desselberger
- Department of Medicine, Addenbrooke’s Hospital, University of Cambridge, Cambridge CB2 0QQ, UK
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10
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Uprety T, Sreenivasan CC, Hause BM, Li G, Odemuyiwa SO, Locke S, Morgan J, Zeng L, Gilsenan WF, Slovis N, Metcalfe L, Carter CN, Timoney P, Horohov D, Wang D, Erol E, Adam E, Li F. Identification of a Ruminant Origin Group B Rotavirus Associated with Diarrhea Outbreaks in Foals. Viruses 2021; 13:1330. [PMID: 34372536 PMCID: PMC8310321 DOI: 10.3390/v13071330] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/02/2021] [Accepted: 07/06/2021] [Indexed: 12/16/2022] Open
Abstract
Equine rotavirus group A (ERVA) is one of the most common causes of foal diarrhea. Starting in February 2021, there was an increase in the frequency of severe watery to hemorrhagic diarrhea cases in neonatal foals in Central Kentucky. Diagnostic investigation of fecal samples failed to detect evidence of diarrhea-causing pathogens including ERVA. Based on Illumina-based metagenomic sequencing, we identified a novel equine rotavirus group B (ERVB) in fecal specimens from the affected foals in the absence of any other known enteric pathogens. Interestingly, the protein sequence of all 11 segments had greater than 96% identity with group B rotaviruses previously found in ruminants. Furthermore, phylogenetic analysis demonstrated clustering of the ERVB with group B rotaviruses of caprine and bovine strains from the USA. Subsequent analysis of 33 foal diarrheic samples by RT-qPCR identified 23 rotavirus B-positive cases (69.69%). These observations suggest that the ERVB originated from ruminants and was associated with outbreaks of neonatal foal diarrhea in the 2021 foaling season in Kentucky. Emergence of the ruminant-like group B rotavirus in foals clearly warrants further investigation due to the significant impact of the disease in neonatal foals and its economic impact on the equine industry.
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Affiliation(s)
- Tirth Uprety
- Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546, USA; (T.U.); (C.C.S.); (P.T.); (D.H.); (D.W.)
| | - Chithra C. Sreenivasan
- Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546, USA; (T.U.); (C.C.S.); (P.T.); (D.H.); (D.W.)
| | - Ben M. Hause
- Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD 57007, USA;
| | - Ganwu Li
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA;
| | - Solomon O. Odemuyiwa
- Veterinary Medical Diagnostic Laboratory, College of Veterinary Medicine, University of Missouri, Columbia, MO 65212, USA;
| | - Stephan Locke
- Veterinary Diagnostic Laboratory, University of Kentucky, Lexington, KY 40512, USA; (S.L.); (J.M.); (L.Z.); (C.N.C.)
| | - Jocelynn Morgan
- Veterinary Diagnostic Laboratory, University of Kentucky, Lexington, KY 40512, USA; (S.L.); (J.M.); (L.Z.); (C.N.C.)
| | - Li Zeng
- Veterinary Diagnostic Laboratory, University of Kentucky, Lexington, KY 40512, USA; (S.L.); (J.M.); (L.Z.); (C.N.C.)
| | | | - Nathan Slovis
- Hagyard Equine Medical Institute, Lexington, KY 40511, USA;
| | - Laurie Metcalfe
- Rood and Riddle Equine Hospital, Lexington, KY 40511, USA; (W.F.G.); (L.M.)
| | - Craig N. Carter
- Veterinary Diagnostic Laboratory, University of Kentucky, Lexington, KY 40512, USA; (S.L.); (J.M.); (L.Z.); (C.N.C.)
| | - Peter Timoney
- Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546, USA; (T.U.); (C.C.S.); (P.T.); (D.H.); (D.W.)
| | - David Horohov
- Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546, USA; (T.U.); (C.C.S.); (P.T.); (D.H.); (D.W.)
| | - Dan Wang
- Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546, USA; (T.U.); (C.C.S.); (P.T.); (D.H.); (D.W.)
| | - Erdal Erol
- Veterinary Diagnostic Laboratory, University of Kentucky, Lexington, KY 40512, USA; (S.L.); (J.M.); (L.Z.); (C.N.C.)
| | - Emma Adam
- Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546, USA; (T.U.); (C.C.S.); (P.T.); (D.H.); (D.W.)
| | - Feng Li
- Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546, USA; (T.U.); (C.C.S.); (P.T.); (D.H.); (D.W.)
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11
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Pan M, Alvarez-Cabrera AL, Kang JS, Wang L, Fan C, Zhou ZH. Asymmetric reconstruction of mammalian reovirus reveals interactions among RNA, transcriptional factor µ2 and capsid proteins. Nat Commun 2021; 12:4176. [PMID: 34234134 PMCID: PMC8263624 DOI: 10.1038/s41467-021-24455-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 06/17/2021] [Indexed: 12/02/2022] Open
Abstract
Mammalian reovirus (MRV) is the prototypical member of genus Orthoreovirus of family Reoviridae. However, lacking high-resolution structures of its RNA polymerase cofactor μ2 and infectious particle, limits understanding of molecular interactions among proteins and RNA, and their contributions to virion assembly and RNA transcription. Here, we report the 3.3 Å-resolution asymmetric reconstruction of transcribing MRV and in situ atomic models of its capsid proteins, the asymmetrically attached RNA-dependent RNA polymerase (RdRp) λ3, and RdRp-bound nucleoside triphosphatase μ2 with a unique RNA-binding domain. We reveal molecular interactions among virion proteins and genomic and messenger RNA. Polymerase complexes in three Spinoreovirinae subfamily members are organized with different pseudo-D3d symmetries to engage their highly diversified genomes. The above interactions and those between symmetry-mismatched receptor-binding σ1 trimers and RNA-capping λ2 pentamers balance competing needs of capsid assembly, external protein removal, and allosteric triggering of endogenous RNA transcription, before, during and after infection, respectively. Mammalian reovirus (MRV) is a double-stranded RNA (dsRNA) virus that affects the gastrointestinal and respiratory tracts. Here, the authors present the 3.3 Å cryo-EM asymmetric reconstruction of transcribing MRV that reveals the organization of the dsRNA genome, RNA interaction with the polymerase complex, and how the polymerase interacts extensively with its co-factor, µ2, to form a transcription enzyme complex, which engages and regulates RNA transcription.
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Affiliation(s)
- Muchen Pan
- CAS Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, China.,Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA, USA.,California NanoSystems Institute, UCLA, Los Angeles, CA, USA.,University of Chinese Academy of Sciences, Beijing, China.,School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, Institute of Translational Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Ana L Alvarez-Cabrera
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA, USA.,California NanoSystems Institute, UCLA, Los Angeles, CA, USA
| | - Joon S Kang
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA, USA.,California NanoSystems Institute, UCLA, Los Angeles, CA, USA.,Molecular Biology Institute, UCLA, Los Angeles, CA, USA
| | - Lihua Wang
- CAS Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, China.,The Interdisciplinary Research Center, Shanghai Synchrotron Radiation Facility, Zhangjiang Laboratory, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China
| | - Chunhai Fan
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, Institute of Translational Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Z Hong Zhou
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA, USA. .,California NanoSystems Institute, UCLA, Los Angeles, CA, USA. .,Molecular Biology Institute, UCLA, Los Angeles, CA, USA.
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12
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Nilsson EM, Sullivan OM, Anderson ML, Argobright HM, Shue TM, Fedowitz FR, LaConte LEW, Esstman SM. Reverse genetic engineering of simian rotaviruses with temperature-sensitive lesions in VP1, VP2, and VP6. Virus Res 2021; 302:198488. [PMID: 34146610 DOI: 10.1016/j.virusres.2021.198488] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 05/24/2021] [Accepted: 06/10/2021] [Indexed: 10/21/2022]
Abstract
Rotaviruses are 11-segmented double-stranded RNA viruses and important causes of acute gastroenteritis in young children. To investigate the functions of specific viral proteins during the rotavirus lifecycle, temperature-sensitive (ts) mutants were previously created using a cultivatable simian strain (SA11) and chemical mutagenesis. These ts SA11 mutants replicate more efficiently at the permissive temperature of 31 °C than at the non-permissive temperature of 39 °C. Prototype strains SA11-tsC, SA11-tsF, and SA11-tsG were mapped to the genes encoding structural proteins VP1, VP2, and VP6, respectively, and putative ts lesions were identified using Sanger sequencing. However, additional background mutations in their genomes had hampered validation of the ts lesions and confounded their use in mechanistic studies. Here, we employed plasmid only-based reverse genetics to engineer recombinant (r) SA11 rotaviruses containing only the putative ts lesions of SA11-tsC (L138P change in VP1), SA11-tsF (A387D change in VP2) or SA11-tsG (S10T, D13H, and A121G changes in VP6). For simplicity, we refer to these newly-engineered, isogenic viruses as rSA11-tsVP1, rSA11-tsVP2, and rSA11-tsVP6. Single-cycle growth assays revealed that these mutants indeed exhibit ts phenotypes with significantly diminished titers (>1.5-logs) at 39 °C versus 31 °C. The rSA11 ts mutants proved genetically stable at the population-level following 3 sequential passages at 39 °C, but individual revertant clones were detected in plaque assays. Heat sensitivity experiments showed that pre-incubation of rSA11-tsVP1 or rSA11-tsVP2, but not rSA11-tsVP6, at 39 °C diminished replication at 31 °C. This result indicates that the ts lesions in VP1 and VP2 affect the incoming virion but those in VP6 affect a later stage of the viral lifecycle. In silico molecular dynamics simulations predicted temperature-dependent, long-range effects of the S10T, D13H, and/or A121G changes on the VP6 structure. Altogether, our results confirm the ts lesions of the original SA11-tsC, SA11-tsF, and SA11-tsG mutants, provide a new set of isogenic strains for investigating aspects of rotavirus replication, and shed light on how the ts lesions might impact VP1, VP2, or VP6 functions.
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Affiliation(s)
- Emil M Nilsson
- Department of Biology, Wake Forest University, Winston-Salem, NC, USA
| | - Owen M Sullivan
- Department of Biology, Wake Forest University, Winston-Salem, NC, USA
| | | | | | - Taylor M Shue
- Department of Biology, Wake Forest University, Winston-Salem, NC, USA
| | | | - Leslie E W LaConte
- Fralin Biomedical Research Institute, Roanoke, VA, USA; Department of Basic Science Education, Virginia Tech Carilion School of Medicine, Roanoke, VA, USA
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13
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Arnold MM, Dijk A, López S. Double‐stranded RNA Viruses. Virology 2021. [DOI: 10.1002/9781119818526.ch2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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14
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Chávez-Maya F, García-Espinosa G, López-Arellano ME, Padilla-Noriega L. Mutations in the VP2 gene of rotavirus associated with benzimidazole sensitivity. Virus Res 2020; 291:198189. [PMID: 33049307 DOI: 10.1016/j.virusres.2020.198189] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 08/23/2020] [Accepted: 10/05/2020] [Indexed: 12/15/2022]
Abstract
Rotavirus species A (RVA) is the etiological agent of acute gastroenteritis in young individuals of various animal species, including humans. Vaccination has helped to reduce the impact of these viruses on humans and some species of domestic mammals, but they do not confer complete immunity, so antirotavirus agents are another important control option. In this study, millimolar concentrations of benzimidazole inhibited the replication of the Rhesus rotavirus (RRV) strain of RVA. Two mutants partially resistant to the inhibitory effect of benzimidazole were independently selected, and their genomes and those of their parental strains were fully sequenced. Most (7/11) mutations occurred in the gene that encodes the VP2 protein, and similarly most of the missense mutations (5/9), including the only one shared by the two mutants (G2,414 → R[G/A], D800 N), occurred in the VP2 gene. Our results identify the VP2 gene as the primary target affected by benzimidazole.
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Affiliation(s)
- Fernando Chávez-Maya
- Departamento de Medicina y Zootecnia de Aves, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Coyoacán 04510, Ciudad de México, Mexico.
| | - Gary García-Espinosa
- Departamento de Medicina y Zootecnia de Aves, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Coyoacán 04510, Ciudad de México, Mexico.
| | - María Eugenia López-Arellano
- Departamento de Helmintología, Centro Nacional de Investigación Disciplinaria en Salud Animal e Inocuidad, INIFAP-México, Jiutepec 62550, Morelos, Mexico.
| | - Luis Padilla-Noriega
- Departamento de Microbiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad Universitaria, edificio A, primer piso, Coyoacán 04510, Ciudad de México, Mexico.
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15
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Abid N, Pietrucci D, Salemi M, Chillemi G. New Insights into the Effect of Residue Mutations on the Rotavirus VP1 Function Using Molecular Dynamic Simulations. J Chem Inf Model 2020; 60:5011-5025. [PMID: 32786703 DOI: 10.1021/acs.jcim.0c00475] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Rotavirus group A remains a major cause of diarrhea in infants and young children worldwide. The permanent emergence of new genotypes puts the potential effectiveness of vaccines under serious questions. Thirteen VP1 structures with mutations mapping to the RNA entry site were analyzed using molecular dynamics simulations, and the results were combined with the experimental findings reported previously. The results revealed structural fluctuations in the protein-protein recognition sites and in the bottleneck of the RNA entry site that may affect the interaction of different proteins and delay the initiation of the viral replication, respectively. Altogether, the structural analysis of VP1 in the region crucial for the initiation of the viral replication, mainly the bottleneck site, may boost efforts to develop antivirals, as they might complement the available vaccines.
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Affiliation(s)
- Nabil Abid
- Laboratory of Transmissible Diseases and Biological Active Substances LR99ES27, Faculty of Pharmacy, University of Monastir, Rue Ibn Sina, 5000 Monastir, Tunisia.,High Institute of Biotechnology of Sidi Thabet, Department of Biotechnology, University Manouba, BP-66, 2020 Ariana-Tunis, Tunisia
| | - Daniele Pietrucci
- Department of Biology, University of Rome Tor Vergata, Via Della Ricerca Scientifica 1, 00133 Rome, Italy
| | - Marco Salemi
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida College of Medicine, Emerging Pathogens Institute, University of Florida, P.O. Box 100009, Gainesville, Florida 32610-3633, United States
| | - Giovanni Chillemi
- Department for Innovation in Biological, Agro-Food and Forest Systems, DIBAF, University of Tuscia, Via S. Camillo de Lellis s.n.c., 01100 Viterbo, Italy.,Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, IBIOM, CNR, Via Giovanni Amendola, 122/O, 70126 Bari, Italy
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16
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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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17
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Kumar D, Singh A, Kumar P, Uversky VN, Rao CD, Giri R. Understanding the penetrance of intrinsic protein disorder in rotavirus proteome. Int J Biol Macromol 2020; 144:892-908. [PMID: 31739058 PMCID: PMC7112477 DOI: 10.1016/j.ijbiomac.2019.09.166] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 09/09/2019] [Accepted: 09/20/2019] [Indexed: 01/03/2023]
Abstract
Rotavirus is a major cause of severe acute gastroenteritis in the infants and young children. The past decade has evidenced the role of intrinsically disordered proteins/regions (IDPs)/(IDPRs) in viral and other diseases. In general, (IDPs)/(IDPRs) are considered as dynamic conformational ensembles that devoid of a specific 3D structure, being associated with various important biological phenomena. Viruses utilize IDPs/IDPRs to survive in harsh environments, to evade the host immune system, and to highjack and manipulate host cellular proteins. The role of IDPs/IDPRs in Rotavirus biology and pathogenicity are not assessed so far, therefore, we have designed this study to deeply look at the penetrance of intrinsic disorder in rotavirus proteome consisting 12 proteins encoded by 11 segments of viral genome. Also, for all human rotaviral proteins, we have deciphered molecular recognition features (MoRFs), which are disorder based binding sites in proteins. Our study shows the wide spread of intrinsic disorder in several rotavirus proteins, primarily the nonstructural proteins NSP3, NSP4, and NSP5 that are involved in viral replication, translation, viroplasm formation and/or maturation. This study may serve as a primer for understanding the role of IDPs/MoRFs in rotavirus biology, design of alternative therapeutic strategies, and development of disorder-based drugs.
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Affiliation(s)
- Deepak Kumar
- Indian Institute of Technology Mandi, VPO Kamand, Himachal Pradesh 175005, India
| | - Ankur Singh
- Indian Institute of Technology Mandi, VPO Kamand, Himachal Pradesh 175005, India
| | - Prateek Kumar
- Indian Institute of Technology Mandi, VPO Kamand, Himachal Pradesh 175005, India
| | - Vladimir N Uversky
- Department of Molecular Medicine and Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
| | - C Durga Rao
- SRM University, AP - Amaravati, Neerukonda, Mangalagiri Mandal Guntur District, Mangalagiri, Andhra Pradesh 522502, India.
| | - Rajanish Giri
- Indian Institute of Technology Mandi, VPO Kamand, Himachal Pradesh 175005, India; BioX Center, Indian Institute of Technology Mandi, Himachal Pradesh, India.
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18
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Abid N, Chillemi G, Salemi M. Coding-Gene Coevolution Analysis of Rotavirus Proteins: A Bioinformatics and Statistical Approach. Genes (Basel) 2019; 11:genes11010028. [PMID: 31878331 PMCID: PMC7016848 DOI: 10.3390/genes11010028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 12/10/2019] [Accepted: 12/19/2019] [Indexed: 01/12/2023] Open
Abstract
Rotavirus remains a major cause of diarrhea in infants and young children worldwide. The permanent emergence of new genotypes puts the potential effectiveness of vaccines under serious question. The distribution of unusual genotypes subject to viral fitness is influenced by interactions among viral proteins. The present work aimed at analyzing the genetic constellation and the coevolution of rotavirus coding genes for the available rotavirus genotypes. Seventy-two full genome sequences of different genetic constellations were analyzed using a genetic algorithm. The results revealed an extensive genome-wide covariance network among the 12 viral proteins. Altogether, the emergence of new genotypes represents a challenge to the outcome and success of vaccination and the coevolutionary analysis of rotavirus proteins may boost efforts to better understand the interaction networks of proteins during viral replication/transcription.
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Affiliation(s)
- Nabil Abid
- Laboratory of Transmissible Diseases and Biological Active Substances LR99ES27, Faculty of Pharmacy, University of Monastir, Rue Ibn Sina, Monastir 5000, Tunisia
- High Institute of Biotechnology of Sidi Thabet, Department of Biotechnology, University Manouba, BP-66, Ariana-Tunis 2020, Tunisia
- Correspondence: or ; Tel.: +216-92–974-000
| | - Giovanni Chillemi
- Department for Innovation in Biological, Agro-food and Forest systems, DIBAF, University of Tuscia, via S. Camillo de Lellis s.n.c., 01100 Viterbo, Italy;
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, IBIOM, CNR, Via Giovanni Amendola, 122/O, 70126 Bari, Italy
| | - Marco Salemi
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida College of Medicine, Emerging Pathogens Institute, P.O. Box 100009, Gainesville, FL 32610-3633, USA;
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19
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In Vitro Double-Stranded RNA Synthesis by Rotavirus Polymerase Mutants with Lesions at Core Shell Contact Sites. J Virol 2019; 93:JVI.01049-19. [PMID: 31341048 DOI: 10.1128/jvi.01049-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 07/17/2019] [Indexed: 12/23/2022] Open
Abstract
The rotavirus polymerase VP1 mediates all stages of viral RNA synthesis within the confines of subviral particles and while associated with the core shell protein VP2. Transcription (positive-strand RNA [+RNA] synthesis) by VP1 occurs within double-layered particles (DLPs), while genome replication (double-stranded RNA [dsRNA] synthesis) by VP1 occurs within assembly intermediates. VP2 is critical for VP1 enzymatic activity; yet, the mechanism by which the core shell protein triggers polymerase function remains poorly understood. Structural analyses of transcriptionally competent DLPs show that VP1 is located beneath the VP2 core shell and sits slightly off-center from each of the icosahedral 5-fold axes. In this position, the polymerase is contacted by the core shell at 5 distinct surface-exposed sites, comprising VP1 residues 264 to 267, 547 to 550, 614 to 620, 968 to 980, and 1022 to 1025. Here, we sought to test the functional significance of these VP2 contact sites on VP1 with regard to polymerase activity. We engineered 19 recombinant VP1 (rVP1) proteins that contained single- or multipoint alanine mutations within each individual contact site and assayed them for the capacity to synthesize dsRNA in vitro in the presence of rVP2. Three rVP1 mutants (E265A/L267A, R614A, and D971A/S978A/I980A) exhibited diminished in vitro dsRNA synthesis. Despite their loss-of-function phenotypes, the mutants did not show major structural changes in silico, and they maintained their overall capacity to bind rVP2 in vitro via their nonmutated contact sites. These results move us toward a mechanistic understanding of rotavirus replication and identify precise VP2-binding sites on the polymerase surface that are critical for its enzymatic activation.IMPORTANCE Rotaviruses are important pathogens that cause severe gastroenteritis in the young of many animals. The viral polymerase VP1 mediates all stages of viral RNA synthesis, and it requires the core shell protein VP2 for its enzymatic activity. Yet, there are several gaps in knowledge about how VP2 engages and activates VP1. Here, we probed the functional significance of 5 distinct VP2 contact sites on VP1 that were revealed through previous structural studies. Specifically, we engineered alanine amino acid substitutions within each of the 5 VP1 regions and assayed the mutant polymerases for the capacity to synthesize RNA in the presence of VP2 in a test tube. Our results identified residues within 3 of the VP2 contact sites that are critical for robust polymerase activity. These results are important because they enhance the understanding of a key step of the rotavirus replication cycle.
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20
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Cryo-EM Reveals Architectural Diversity in Active Rotavirus Particles. Comput Struct Biotechnol J 2019; 17:1178-1183. [PMID: 31467657 PMCID: PMC6710475 DOI: 10.1016/j.csbj.2019.07.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 07/26/2019] [Accepted: 07/27/2019] [Indexed: 12/04/2022] Open
Abstract
Rotavirus is a well-studied RNA virus that causes severe gastroenteritis in children. During viral entry, the outer layer of the virion is shed, creating a double-layered particle (DLP) that is competent to perform viral transcription (i.e., mRNA synthesis) and launch infection. While inactive forms of rotavirus DLPs have been structurally characterized in detail, information about the transcriptionally-active DLP remains limited. Here, we used cryo-Electron Microscopy (cryo-EM) and 3D image reconstructions to compare the structures of internal protein components in transcriptionally-active versus inactive DLPs. Our findings showed that transcriptionally-active DLPs gained internal order as mRNA synthesis unfolded, while inactive DLPs remained dynamically disordered. Regions of viral protein/RNA constituents were analyzed across two different axes of symmetry to provide a more comprehensive view of moving components. Taken together, our results bring forth a new view of active DLPs, which may enable future pharmacological strategies aimed at obliterating rotavirus transcription as a therapeutic approach.
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21
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Group A Rotavirus VP1 Polymerase and VP2 Core Shell Proteins: Intergenotypic Sequence Variation and In Vitro Functional Compatibility. J Virol 2019; 93:JVI.01642-18. [PMID: 30355692 DOI: 10.1128/jvi.01642-18] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 10/16/2018] [Indexed: 02/05/2023] Open
Abstract
Group A rotaviruses (RVAs) are classified according to a nucleotide sequence-based system that assigns a genotype to each of the 11 double-stranded RNA (dsRNA) genome segments. For the segment encoding the VP1 polymerase, 22 genotypes (R1 to R22) are defined with an 83% nucleotide identity cutoff value. For the segment encoding the VP2 core shell protein, which is a functional VP1-binding partner, 20 genotypes (C1 to C20) are defined with an 84% nucleotide identity cutoff value. However, the extent to which the VP1 and VP2 proteins encoded by these genotypes differ in their sequences or interactions has not been described. Here, we sought to (i) delineate the relationships and sites of variation for VP1 and VP2 proteins belonging to the known RVA genotypes and (ii) correlate intergenotypic sequence diversity with functional VP1-VP2 interaction(s) during dsRNA synthesis. Using bioinformatic approaches, we revealed which VP1 and VP2 genotypes encode divergent proteins and identified the positional locations of amino acid changes in the context of known structural domains/subdomains. We then employed an in vitro dsRNA synthesis assay to test whether genotype R1, R2, R4, and R7 VP1 polymerases could be enzymatically activated by genotype C1, C2, C4, C5, and C7 VP2 core shell proteins. Genotype combinations that were incompatible informed the rational design and in vitro testing of chimeric mutant VP1 and VP2 proteins. The results of this study connect VP1 and VP2 nucleotide-level diversity to protein-level diversity for the first time, and they provide new insights into regions/residues critical for VP1-VP2 interaction(s) during viral genome replication.IMPORTANCE Group A rotaviruses (RVAs) are widespread in nature, infecting numerous mammalian and avian hosts and causing severe gastroenteritis in human children. RVAs are classified using a system that assigns a genotype to each viral gene according to its nucleotide sequence. To date, 22 genotypes have been described for the gene encoding the viral polymerase (VP1), and 20 genotypes have been described for the gene encoding the core shell protein (VP2). Here, we analyzed if/how the VP1 and VP2 proteins encoded by the known RVA genotypes differ from each other in their sequences. We also used a biochemical approach to test whether the intergenotypic sequence differences influenced how VP1 and VP2 functionally engage each other to mediate RNA synthesis in a test tube. This work is important because it increases our understanding of RVA protein-level diversity and raises new ideas about the VP1-VP2 binding interface(s) that is important for viral replication.
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22
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Rodríguez JM, Luque D. Structural Insights into Rotavirus Entry. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1215:45-68. [DOI: 10.1007/978-3-030-14741-9_3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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23
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Infectious Bursal Disease Virus Hijacks Endosomal Membranes as the Scaffolding Structure for Viral Replication. J Virol 2018. [PMID: 29540593 DOI: 10.1128/jvi.01964-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Birnaviruses are unconventional members of the group of double-stranded RNA (dsRNA) viruses that are characterized by the lack of a transcriptionally active inner core. Instead, the birnaviral particles organize their genome in ribonucleoprotein complexes (RNPs) composed by dsRNA segments, the dsRNA-binding VP3 protein, and the virally encoded RNA-dependent RNA polymerase (RdRp). This and other structural features suggest that birnaviruses may follow a completely different replication program from that followed by members of the Reoviridae family, supporting the hypothesis that birnaviruses are the evolutionary link between single-stranded positive RNA (+ssRNA) and dsRNA viruses. Here we demonstrate that infectious bursal disease virus (IBDV), a prototypical member of the Birnaviridae family, hijacks endosomal membranes of infected cells through the interaction of a viral protein, VP3, with the phospholipids on the cytosolic leaflet of these compartments for replication. Employing a mutagenesis approach, we demonstrated that VP3 domain PATCH 2 (P2) mediates the association of VP3 with the endosomal membranes. To determine the role of VP3 P2 in the context of the virus replication cycle, we used avian cells stably overexpressing VP3 P2 for IBDV infection. Importantly, the intra- and extracellular virus yields, as well as the intracellular levels of VP2 viral capsid protein, were significantly diminished in cells stably overexpressing VP3 P2. Together, our results indicate that the association of VP3 with endosomes has a relevant role in the IBDV replication cycle. This report provides direct experimental evidence for membranous compartments such as endosomes being required by a dsRNA virus for its replication. The results also support the previously proposed role of birnaviruses as an evolutionary link between +ssRNA and dsRNA viruses.IMPORTANCE Infectious bursal disease (IBD; also called Gumboro disease) is an acute, highly contagious immunosuppressive disease that affects young chickens and spreads worldwide. The etiological agent of IBD is infectious bursal disease virus (IBDV). This virus destroys the central immune organ (bursa of Fabricius), resulting in immunosuppression and reduced responses of chickens to vaccines, which increase their susceptibility to other pathogens. IBDV is a member of Birnaviridae family, which comprises unconventional members of dsRNA viruses, whose replication strategy has been scarcely studied. In this report we show that IBDV hijacks the endosomes of the infected cells for establishing viral replication complexes via the association of the ribonucleoprotein complex component VP3 with the phospholipids in the cytosolic leaflet of endosomal membranes. We show that this interaction is mediated by the VP3 PATCH 2 domain and demonstrate its relevant role in the context of viral infection.
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24
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Genetic determinants restricting the reassortment of heterologous NSP2 genes into the simian rotavirus SA11 genome. Sci Rep 2017; 7:9301. [PMID: 28839154 PMCID: PMC5571167 DOI: 10.1038/s41598-017-08068-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 07/06/2017] [Indexed: 01/02/2023] Open
Abstract
Rotaviruses (RVs) can evolve through the process of reassortment, whereby the 11 double-stranded RNA genome segments are exchanged among strains during co-infection. However, reassortment is limited in cases where the genes or encoded proteins of co-infecting strains are functionally incompatible. In this study, we employed a helper virus-based reverse genetics system to identify NSP2 gene regions that correlate with restricted reassortment into simian RV strain SA11. We show that SA11 reassortants with NSP2 genes from human RV strains Wa or DS-1 were efficiently rescued and exhibit no detectable replication defects. However, we could not rescue an SA11 reassortant with a human RV strain AU-1 NSP2 gene, which differs from that of SA11 by 186 nucleotides (36 amino acids). To map restriction determinants, we engineered viruses to contain chimeric NSP2 genes in which specific regions of AU-1 sequence were substituted with SA11 sequence. We show that a region spanning AU-1 NSP2 gene nucleotides 784–820 is critical for the observed restriction; yet additional determinants reside in other gene regions. In silico and in vitro analyses were used to predict how the 784–820 region may impact NSP2 gene/protein function, thereby informing an understanding of the reassortment restriction mechanism.
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Abstract
In infected cells rotavirus (RV) replicates in viroplasms, cytosolic structures that require a stabilized microtubule (MT) network for their assembly, maintenance of the structure and perinuclear localization. Therefore, we hypothesized that RV could interfere with the MT-breakdown that takes place in mitosis during cell division. Using synchronized RV-permissive cells, we show that RV infection arrests the cell cycle in S/G2 phase, thus favoring replication by improving viroplasms formation, viral protein translation, and viral assembly. The arrest in S/G2 phase is independent of the host or viral strain and relies on active RV replication. RV infection causes cyclin B1 down-regulation, consistent with blocking entry into mitosis. With the aid of chemical inhibitors, the cytoskeleton network was linked to specific signaling pathways of the RV-induced cell cycle arrest. We found that upon RV infection Eg5 kinesin was delocalized from the pericentriolar region to the viroplasms. We used a MA104-Fucci system to identify three RV proteins (NSP3, NSP5, and VP2) involved in cell cycle arrest in the S-phase. Our data indicate that there is a strong correlation between the cell cycle arrest and RV replication.
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Kundu A, Bose M, Roy M, Dutta S, Biswas P, Gautam P, Das AK, Ghosh AK. Molecular insights into RNA-binding properties of Escherichia coli-expressed RNA-dependent RNA polymerase of Antheraea mylitta cytoplasmic polyhedrosis virus. Arch Virol 2017; 162:2727-2736. [PMID: 28589512 DOI: 10.1007/s00705-017-3412-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 05/15/2017] [Indexed: 11/30/2022]
Abstract
Antheraea mylitta cytoplasmic polyhedrosis virus (AmCPV) is responsible for morbidity of the Indian non-mulberry silkworm, A. mylitta. AmCPV belongs to the family Reoviridae and has 11 double-stranded (ds) RNA genome segments (S1-S11). Segment 2 (S2) encodes a 123-kDa polypeptide with RNA-dependent RNA polymerase (RdRp) activity. To examine the RNA-binding properties of the viral polymerase, the full-length RdRp and its three domains (N-terminal, polymerase and C-terminal domains) were expressed in Escherichia coli BL21 (DE3) cells with hexahistidine and trigger factor tag fused consecutively at its amino terminus, and the soluble fusion proteins were purified. The purified full-length polymerase specifically bound to the 3' untranslated region (3'-UTR) of a viral plus-sense (+) strand RNA with strong affinity regardless of the salt concentrations, but the isolated polymerase domain of the enzyme exhibited poor RNA-binding ability. Further, the RdRp recognition signals were found to be different from the cis-acting signals that promote minus-sense (-) strand RNA synthesis, because different internal regions of the 3'-UTR of the (+) strand RNA did not effectively compete out the binding of RdRp to the intact 3'-UTR of the (+) strand RNA, but all of these RNA molecules could serve as templates for (-) strand RNA synthesis by the polymerase.
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Affiliation(s)
- Anirban Kundu
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India
| | - Madhuparna Bose
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India
| | - Madhurima Roy
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India
| | - Soumita Dutta
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India
| | - Poulomi Biswas
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India
| | - Pradeep Gautam
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India
| | - Amit Kumar Das
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India
| | - Ananta Kumar Ghosh
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India.
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A Temperature-Sensitive Lesion in the N-Terminal Domain of the Rotavirus Polymerase Affects Its Intracellular Localization and Enzymatic Activity. J Virol 2017; 91:JVI.00062-17. [PMID: 28100623 DOI: 10.1128/jvi.00062-17] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 01/16/2017] [Indexed: 12/20/2022] Open
Abstract
Temperature-sensitive (ts) mutants of simian rotavirus (RV) strain SA11 have been previously created to investigate the functions of viral proteins during replication. One mutant, SA11-tsC, has a mutation that maps to the gene encoding the VP1 polymerase and shows diminished growth and RNA synthesis at 39°C compared to that at 31°C. In the present study, we sequenced all 11 genes of SA11-tsC, confirming the presence of an L138P mutation in the VP1 N-terminal domain and identifying 52 additional mutations in four other viral proteins (VP4, VP7, NSP1, and NSP2). To investigate whether the L138P mutation induces a ts phenotype in VP1 outside the SA11-tsC genetic context, we employed ectopic expression systems. Specifically, we tested whether the L138P mutation affects the ability of VP1 to localize to viroplasms, which are the sites of RV RNA synthesis, by expressing the mutant form as a green fluorescent protein (GFP) fusion protein (VP1L138P-GFP) (i) in wild-type SA11-infected cells or (ii) in uninfected cells along with viroplasm-forming proteins NSP2 and NSP5. We found that VP1L138P-GFP localized to viroplasms and interacted with NSP2 and/or NSP5 at 31°C but not at 39°C. Next, we tested the enzymatic activity of a recombinant mutant polymerase (rVP1L138P) in vitro and found that it synthesized less RNA at 39°C than at 31°C, as well as less RNA than the control at all temperatures. Together, these results provide a mechanistic basis for the ts phenotype of SA11-tsC and raise important questions about the role of leucine 138 in supporting key protein interactions and the catalytic function of the VP1 polymerase.IMPORTANCE RVs cause diarrhea in the young of many animal species, including humans. Despite their medical and economic importance, gaps in knowledge exist about how these viruses replicate inside host cells. Previously, a mutant simian RV (SA11-tsC) that replicates worse at higher temperatures was identified. This virus has an amino acid mutation in VP1, which is the enzyme responsible for copying the viral RNA genome. The mutation is located in a poorly understood region of the polymerase called the N-terminal domain. In this study, we determined that the mutation reduces the ability of VP1 to properly localize within infected cells at high temperatures, as well as reduced the ability of the enzyme to copy viral RNA in a test tube. The results of this study explain the temperature sensitivity of SA11-tsC and shed new light on functional protein-protein interaction sites of VP1.
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Abstract
Segmented RNA viruses are widespread in nature and include important human, animal and plant pathogens, such as influenza viruses and rotaviruses. Although the origin of RNA virus genome segmentation remains elusive, a major consequence of this genome structure is the capacity for reassortment to occur during co-infection, whereby segments are exchanged among different viral strains. Therefore, reassortment can create viral progeny that contain genes that are derived from more than one parent, potentially conferring important fitness advantages or disadvantages to the progeny virus. However, for segmented RNA viruses that package their multiple genome segments into a single virion particle, reassortment also requires genetic compatibility between parental strains, which occurs in the form of conserved packaging signals, and the maintenance of RNA and protein interactions. In this Review, we discuss recent studies that examined the mechanisms and outcomes of reassortment for three well-studied viral families - Cystoviridae, Orthomyxoviridae and Reoviridae - and discuss how these findings provide new perspectives on the replication and evolution of segmented RNA viruses.
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Kundu A, Roychowdhury A, Bose M, Das AK, Ghosh AK. Reconstitution of the RNA-dependent RNA polymerase activity of Antheraea mylitta cypovirus in vitro using separately expressed different functional domains of the enzyme. J Gen Virol 2016; 97:1709-1719. [PMID: 27008451 DOI: 10.1099/jgv.0.000463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Antheraea mylitta cytoplasmic polyhedrosis virus is a segmented dsRNA virus of the family Reoviridae. Segment 2 (S2)-encoded RNA-dependent RNA polymerase (RdRp) helps the virus to propagate its genome in the host cell of the silkworm, Antheraea mylitta. Cloning, expression, purification and functional analysis of individual domains of RdRp have demonstrated that the purified domains interact in vitro. The central polymerase domain (PD) shows nucleotide binding properties, but neither the N-terminal domain (NTD) nor the C-terminal domain (CTD). Isolated PD does not exhibit RdRp activity but this activity can be reconstituted when all three domains are included in the reaction mixture. Molecular dynamics simulation suggests that the isolated PD has increased internal motions in comparison to when it is associated with the NTD and CTD. The motions of the separated PD may lead to the formation of a less accessible RNA template-binding channel and, thus, impair RdRp activity.
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Affiliation(s)
- Anirban Kundu
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur-721302, India
| | - Amlan Roychowdhury
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur-721302, India
| | - Madhuparna Bose
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur-721302, India
| | - Amit Kumar Das
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur-721302, India
| | - Ananta K Ghosh
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur-721302, India
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Zhang X, Ding K, Yu X, Chang W, Sun J, Zhou ZH. In situ structures of the segmented genome and RNA polymerase complex inside a dsRNA virus. Nature 2015; 527:531-534. [PMID: 26503045 PMCID: PMC5086257 DOI: 10.1038/nature15767] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 10/07/2015] [Indexed: 01/15/2023]
Abstract
Viruses in the Reoviridae, like the triple-shelled human rotavirus and the single-shelled insect cytoplasmic polyhedrosis virus (CPV), all package a genome of segmented double-stranded RNAs (dsRNAs) inside the viral capsid and carry out endogenous messenger RNA synthesis through a transcriptional enzyme complex (TEC). By direct electron-counting cryoelectron microscopy and asymmetric reconstruction, we have determined the organization of the dsRNA genome inside quiescent CPV (q-CPV) and the in situ atomic structures of TEC within CPV in both quiescent and transcribing (t-CPV) states. We show that the ten segmented dsRNAs in CPV are organized with ten TECs in a specific, non-symmetric manner, with each dsRNA segment attached directly to a TEC. The TEC consists of two extensively interacting subunits: an RNA-dependent RNA polymerase (RdRP) and an NTPase VP4. We find that the bracelet domain of RdRP undergoes marked conformational change when q-CPV is converted to t-CPV, leading to formation of the RNA template entry channel and access to the polymerase active site. An amino-terminal helix from each of two subunits of the capsid shell protein (CSP) interacts with VP4 and RdRP. These findings establish the link between sensing of environmental cues by the external proteins and activation of endogenous RNA transcription by the TEC inside the virus.
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MESH Headings
- Capsid Proteins/chemistry
- Capsid Proteins/metabolism
- Capsid Proteins/ultrastructure
- Catalytic Domain
- Cryoelectron Microscopy
- Genome, Viral/genetics
- Models, Molecular
- Multienzyme Complexes/chemistry
- Multienzyme Complexes/metabolism
- Multienzyme Complexes/ultrastructure
- Nucleoside-Triphosphatase/metabolism
- Nucleoside-Triphosphatase/ultrastructure
- Protein Subunits/chemistry
- Protein Subunits/metabolism
- RNA, Double-Stranded/genetics
- RNA, Double-Stranded/ultrastructure
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- RNA, Messenger/ultrastructure
- RNA, Viral/biosynthesis
- RNA, Viral/genetics
- RNA, Viral/ultrastructure
- RNA-Dependent RNA Polymerase/chemistry
- RNA-Dependent RNA Polymerase/metabolism
- RNA-Dependent RNA Polymerase/ultrastructure
- Reoviridae/enzymology
- Reoviridae/genetics
- Reoviridae/ultrastructure
- Templates, Genetic
- Transcription, Genetic
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Affiliation(s)
- Xing Zhang
- California Nanosystems Institute, Los Angeles, CA 90095, USA
| | - Ke Ding
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA 90095, USA
- Bioengineering, University of California, Los Angeles, CA 90095, USA
| | - Xuekui Yu
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA 90095, USA
| | - Winston Chang
- California Nanosystems Institute, Los Angeles, CA 90095, USA
| | - Jingchen Sun
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA 90095, USA
- Subtropical Sericulture and Mulberry Resources Protection and Safety Engineering Research Center, Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, Guangdong 510642, China
| | - Z. Hong Zhou
- California Nanosystems Institute, Los Angeles, CA 90095, USA
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA 90095, USA
- Bioengineering, University of California, Los Angeles, CA 90095, USA
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Infectious Bursal Disease Virus VP3 Upregulates VP1-Mediated RNA-Dependent RNA Replication. J Virol 2015; 89:11165-8. [PMID: 26311889 DOI: 10.1128/jvi.00218-15] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 08/15/2015] [Indexed: 11/20/2022] Open
Abstract
Genome replication is a critical step in virus life cycles. Here, we analyzed the role of the infectious bursal disease virus (IBDV) VP3, a major component of IBDV ribonucleoprotein complexes, on the regulation of VP1, the virus-encoded RNA-dependent RNA polymerase (RdRp). Data show that VP3, as well as a peptide mimicking its C-terminal domain, efficiently stimulates the ability of VP1 to replicate synthetic single-stranded RNA templates containing the 3' untranslated regions (UTRs) from the IBDV genome segments.
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Borodavka A, Ault J, Stockley PG, Tuma R. Evidence that avian reovirus σNS is an RNA chaperone: implications for genome segment assortment. Nucleic Acids Res 2015; 43:7044-57. [PMID: 26109354 PMCID: PMC4538827 DOI: 10.1093/nar/gkv639] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 06/06/2015] [Accepted: 06/09/2015] [Indexed: 12/15/2022] Open
Abstract
Reoviruses are important human, animal and plant pathogens having 10-12 segments of double-stranded genomic RNA. The mechanisms controlling the assortment and packaging of genomic segments in these viruses, remain poorly understood. RNA-protein and RNA-RNA interactions between viral genomic segment precursors have been implicated in the process. While non-structural viral RNA-binding proteins, such as avian reovirus σNS, are essential for virus replication, the mechanism by which they assist packaging is unclear. Here we demonstrate that σNS assembles into stable elongated hexamers in vitro, which bind single-stranded nucleic acids with high affinity, but little sequence specificity. Using ensemble and single molecule fluorescence spectroscopy, we show that σNS also binds to a partially double-stranded RNA, resulting in gradual helix unwinding. The hexamer can bind multiple RNA molecules and exhibits strand-annealing activity, thus mediating conversion of metastable, intramolecular stem-loops into more stable heteroduplexes. We demonstrate that the ARV σNS acts as an RNA chaperone facilitating specific RNA-RNA interactions between genomic precursors during segment assortment and packaging.
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Affiliation(s)
- Alexander Borodavka
- School of Molecular and Cellular Biology & Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - James Ault
- School of Molecular and Cellular Biology & Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Peter G Stockley
- School of Molecular and Cellular Biology & Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Roman Tuma
- School of Molecular and Cellular Biology & Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
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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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VP7 of Rhesus monkey rotavirus RRV contributes to diabetes acceleration in association with an elevated anti-rotavirus antibody response. Virology 2014; 468-470:504-509. [DOI: 10.1016/j.virol.2014.09.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 08/12/2014] [Accepted: 09/09/2014] [Indexed: 11/19/2022]
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Gridley CL, Patton JT. Regulation of rotavirus polymerase activity by inner capsid proteins. Curr Opin Virol 2014; 9:31-8. [PMID: 25243800 DOI: 10.1016/j.coviro.2014.08.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2014] [Revised: 08/28/2014] [Accepted: 08/29/2014] [Indexed: 11/16/2022]
Abstract
Rotavirus, a cause of pediatric gastroenteritis, has a genome consisting of 11 segments of double-stranded (ds)RNA surrounded by a triple-layered protein capsid. The rotavirus RNA-dependent RNA polymerase, VP1, synthesizes both dsRNA and plus-strand RNA (+RNA) within subviral particles. Structural analyses of the rotavirus capsid and polymerase, combined with functional studies of purified capsid proteins, indicate that the inner capsid protein controls the initiation of RNA synthesis by VP1. Whether VP1 directs dsRNA versus +RNA synthesis may be regulated by the impact of the viral RNA capping enzyme on the position of the polymerase plug, a flexible element that inserts into one of the polymerase's RNA exit tunnels. This review discusses recent findings and ideas into the mechanisms used by rotavirus capsid proteins to control the activities of its viral polymerase and to coordinate RNA synthesis with the assembly of virus particles.
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Affiliation(s)
- Chelsea L Gridley
- Rotavirus Molecular Biology Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, United States
| | - John T Patton
- Rotavirus Molecular Biology Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, United States.
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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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Teimoori A, Soleimanjahi H, Makvandi M. Characterization and Transferring of Human Rotavirus Double-Layered Particles in MA104 Cells. Jundishapur J Microbiol 2014; 7:e10375. [PMID: 25371799 PMCID: PMC4217670 DOI: 10.5812/jjm.10375] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 04/25/2013] [Accepted: 06/01/2013] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Rotavirus (RV) is a major cause of gastroenteritis in infants and children and is one of the most severe public health problems. Rotaviruses outer layer contains two proteins including VP4 and VP7. These proteins are necessary for host-cell binding and penetration. TLP (triple layer virus particle) of RV is a complete infectious virion that binds to the target cells and internalized at the cytoplasm. The DLP (double layer virus particle) is a non-infectious particle that is formed through exclusion of the outer layer proteins including VP4 and VP7. These DLPs are the transcriptionally active forms of rotavirus. OBJECTIVES The aim of this study was to transfer DLP of RV into cytoplasm of MA104 cells by Lipofectamine and to analyze their replication. MATERIALS AND METHODS Initially, rotavirus was purified by CsCl discontinuous gradient and DLP was separated from TLP based on density differences. For confirmation, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of the proteins were conducted Then the purified DLP of RV was transferred into MA104 cells using Lipofectamine. RESULTS We attempt to avoid the attachment and entry of the rotavirus by using Lipofectamine to mediate the delivery of viral particles directly into the cytoplasm. DLP was endocytosed into the cytoplasm following treatment by Lipofectamine and then replicated in cytoplasm. CONCLUSIONS Therefore the non-infectious DLPs were became infectious if introduced into the cytoplasm of permissive and cancerous cells, without passing attachment and entry process.
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Affiliation(s)
- Ali Teimoori
- Department of Virology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, IR Iran
| | - Hoorieh Soleimanjahi
- Department of Virology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, IR Iran
- Corresponding author: Hoorieh Soleimanjahi, Department of Virology, Faculty of Medical Science, Tarbiat Modares University, Tehran, IR Iran. Tel/Fax: +98-2182883561, E-mail:
| | - Manoochehr Makvandi
- Department of Virology, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran
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Rescue of infectious birnavirus from recombinant ribonucleoprotein complexes. PLoS One 2014; 9:e87790. [PMID: 24498196 PMCID: PMC3907549 DOI: 10.1371/journal.pone.0087790] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 01/02/2014] [Indexed: 11/19/2022] Open
Abstract
Birnaviruses are unconventional members of the icosahedral double-stranded (dsRNA) RNA virus group. The main differential birnavirus trait is the lack of the inner icosahedral transcriptional core, a ubiquitous structure conserved in all other icosahedral dsRNA viruses, that shelters the genome from cellular dsRNA sensors and provide the enzymatic machinery to produce and extrude mature messenger RNAs. In contrast, birnaviral particles enclose ribonucleoprotein (RNP) complexes formed by the genome segments, the dsRNA-binding VP3 polypeptide and the virus-encoded RNA polymerase (RdRp). The presence of RNPs suggests that the birnavirus replication program might exhibit significant differences with respect to those of prototypal dsRNA viruses. However, experimental evidences supporting this hypothesis are as yet scarce. Of particular relevance for the understanding of birnavirus replication is to determine whether RNPs act as intracellular capsid-independent transcriptional units. Our study was focused to answer this question using the infectious bursal disease virus (IBDV), the best characterized birnavirus, as model virus. Here, we describe the intracellular assembly of functional IBDV RNPs in the absence of the virus-encoded VP2 capsid polypeptide. Recombinant RNPs are generated upon coexpression of the IBDV VP1 and RdRp polypeptides and transfection of purified virus dsRNA. Presented data show that recombinant RNPs direct the expression of the IBDV polypeptide repertoire and the production of infectious virus in culture cells. Results described in this report constitute the first direct experimental evidence showing that birnaviral RNPs are intracellularly active in the absence of the virus capsid. This finding is consistent with presented data indicating that RNP formation precedes virus assembly in IBDV-infected cells, and supports the recently proposed IBDV replication model entailing the release of RNPs during the initial stages of the infection. Indeed, results presented here also support the previously proposed evolutionary connection between birnaviruses and positive-strand single-stranded RNA viruses.
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McDonald SM. RNA synthetic mechanisms employed by diverse families of RNA viruses. WILEY INTERDISCIPLINARY REVIEWS-RNA 2013; 4:351-67. [PMID: 23606593 PMCID: PMC7169773 DOI: 10.1002/wrna.1164] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
RNA viruses are ubiquitous in nature, infecting every known organism on the planet. These viruses can also be notorious human pathogens with significant medical and economic burdens. Central to the lifecycle of an RNA virus is the synthesis of new RNA molecules, a process that is mediated by specialized virally encoded enzymes called RNA‐dependent RNA polymerases (RdRps). RdRps directly catalyze phosphodiester bond formation between nucleoside triphosphates in an RNA‐templated manner. These enzymes are strikingly conserved in their structural and functional features, even among diverse RNA viruses belonging to different families. During host cell infection, the activities of viral RdRps are often regulated by viral cofactor proteins. Cofactors can modulate the type and timing of RNA synthesis by directly engaging the RdRp and/or by indirectly affecting its capacity to recognize template RNA. High‐resolution structures of RdRps as apoenzymes, bound to RNA templates, in the midst of catalysis, and/or interacting with regulatory cofactor proteins, have dramatically increased our understanding of viral RNA synthetic mechanisms. Combined with elegant biochemical studies, such structures are providing a scientific platform for the rational design of antiviral agents aimed at preventing and treating RNA virus‐induced diseases. WIREs RNA 2013, 4:351–367. doi: 10.1002/wrna.1164 This article is categorized under:
RNA Interactions with Proteins and Other Molecules > RNA–Protein Complexes RNA in Disease and Development > RNA in Disease
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Affiliation(s)
- Sarah M McDonald
- Virginia Tech Carilion Research Institute and School of Medicine, Roanoke, VA, USA.
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Boudreaux CE, Vile DC, Gilmore BL, Tanner JR, Kelly DF, McDonald SM. Rotavirus core shell subdomains involved in polymerase encapsidation into virus-like particles. J Gen Virol 2013; 94:1818-1826. [PMID: 23596269 DOI: 10.1099/vir.0.052951-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The triple-layered rotavirus virion encases an 11-segmented, dsRNA genome and 11-12 copies of the viral polymerase (VP1). VP1 transcribes and replicates the genome while tethered beneath the VP2 core shell. Genome replication (i.e. minus-strand RNA synthesis) by VP1 occurs in association with core assembly. During this process, VP2 directly engages VP1, thereby (i) packaging the polymerase into a nascent core and (ii) triggering the enzyme to initiate minus-strand RNA synthesis on bound plus-strand RNA templates. Recent work has shed light on VP2 regions important for VP1 enzymic activity. In the current study, we sought to investigate VP2 subdomains involved in the encapsidation of VP1 into recombinant virus-like particles (VLPs), which are formed of VP2 and the middle layer virion protein (VP6). We showed that strain SA11 VLPs efficiently encapsidated SA11 VP1, but not the genetically divergent Bristol VP1. VLPs made with an SA11 VP2 mutant lacking residues 1-10 of the amino-terminal domain (NTD) were still able to encapsidate VP1; however, removal of the entire NTD (residues 1-102) completely abolished polymerase packaging. We also showed that a chimeric VP2 protein containing the NTD and dimer-forming subdomain of strain Bristol VP2 can efficiently encapsidate SA11 VP1. These results suggest that the VP2 NTD and dimer-forming subdomain play important, albeit non-specific, roles in both VP1 packaging and activation. When combined with previous work, the results of this study support the notion that the same VP2 regions that engage VP1 during activation are also involved in packaging the enzyme into the core.
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Affiliation(s)
| | - Donald C Vile
- Virginia Tech Carilion School of Medicine, Roanoke, VA, USA.,Virginia Tech Carilion Research Institute, Roanoke, VA, USA
| | | | | | - Deborah F Kelly
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, USA.,Virginia Tech Carilion School of Medicine, Roanoke, VA, USA.,Virginia Tech Carilion Research Institute, Roanoke, VA, USA
| | - Sarah M McDonald
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg, VA, USA.,Virginia Tech Carilion School of Medicine, Roanoke, VA, USA.,Virginia Tech Carilion Research Institute, Roanoke, VA, USA
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Martin D, Charpilienne A, Parent A, Boussac A, D'Autreaux B, Poupon J, Poncet D. The rotavirus nonstructural protein NSP5 coordinates a [2Fe‐2S] iron‐sulfur cluster that modulates interaction to RNA. FASEB J 2012. [DOI: 10.1096/fj.12-217182] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Davy Martin
- Virologie Moléculaire et StructuraleUnité Propre de Recherche du Centre National de la Recherche Scientifique (UPR‐CNRS) 3296Unité Sous Contrat de l' Institut National de la Recherche Agronomique (USC‐INRA)Gif sur YvetteFrance
| | - Annie Charpilienne
- Virologie Moléculaire et StructuraleUnité Propre de Recherche du Centre National de la Recherche Scientifique (UPR‐CNRS) 3296Unité Sous Contrat de l' Institut National de la Recherche Agronomique (USC‐INRA)Gif sur YvetteFrance
| | - Aubérie Parent
- Institut de Chimie des Substances NaturellesUPR‐CNRS 2301Centre de Recherche de GifCNRSGif sur YvetteFrance
| | - Alain Boussac
- Institut de Biologie et de Technologies de Saclay (iBiTec‐S)Service de Bioénergétique, Biologie Structurale et Mécanismes (SB2SM)Unité Mixte de Recherche (UMR‐CNRS) 8221Commissariat à l'Énergie Atomique et aux Énergies Alternatives (CEA)‐SaclayGif sur YvetteFrance
| | - Benoit D'Autreaux
- Institut de Chimie des Substances NaturellesUPR‐CNRS 2301Centre de Recherche de GifCNRSGif sur YvetteFrance
| | - Joël Poupon
- Laboratoire de Toxicologie BiologiqueAssistance Publique–Hôpitaux de Paris (AP‐HP), Hôpital LariboisièreParisFrance
| | - Didier Poncet
- Virologie Moléculaire et StructuraleUnité Propre de Recherche du Centre National de la Recherche Scientifique (UPR‐CNRS) 3296Unité Sous Contrat de l' Institut National de la Recherche Agronomique (USC‐INRA)Gif sur YvetteFrance
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Norovirus RNA synthesis is modulated by an interaction between the viral RNA-dependent RNA polymerase and the major capsid protein, VP1. J Virol 2012; 86:10138-49. [PMID: 22787222 DOI: 10.1128/jvi.01208-12] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Using a cell-based assay for RNA synthesis by the RNA-dependent RNA polymerase (RdRp) of noroviruses, we previously observed that VP1, the major structural protein of the human GII.4 norovirus, enhanced the GII.4 RdRp activity but not that of the related murine norovirus (MNV) or other unrelated RNA viruses (C. V. Subba-Reddy, I. Goodfellow, and C. C. Kao, J. Virol. 85:13027-13037, 2011). Here, we examine the mechanism of VP1 enhancement of RdRp activity and the mechanism of mouse norovirus replication. We determined that the GII.4 and MNV VP1 proteins can enhance cognate RdRp activities in a concentration-dependent manner. The VP1 proteins coimmunoprecipitated with their cognate RdRps. Coexpression of individual domains of VP1 with the viral RdRps showed that the VP1 shell domain (SD) was sufficient to enhance polymerase activity. Using SD chimeras from GII.4 and MNV, three loops connecting the central β-barrel structure were found to be responsible for the species-specific enhancement of RdRp activity. A differential scanning fluorimetry assay showed that recombinant SDs can bind to the purified RdRps in vitro. An MNV replicon with a frameshift mutation in open reading frame 2 (ORF2) that disrupts VP1 expression was defective for RNA replication, as quantified by luciferase reporter assay and real-time quantitative reverse transcription-PCR (qRT-PCR). Trans-complementation of VP1 or its SD significantly recovered the VP1 knockout MNV replicon replication, and the presence or absence of VP1 affected the kinetics of viral RNA synthesis. The results document a regulatory role for VP1 in the norovirus replication cycle, further highlighting the paradigm of viral structural proteins playing additional functional roles in the virus life cycle.
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Trask SD, Boehme KW, Dermody TS, Patton JT. Comparative analysis of Reoviridae reverse genetics methods. Methods 2012; 59:199-206. [PMID: 22687622 DOI: 10.1016/j.ymeth.2012.05.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 04/16/2012] [Accepted: 05/31/2012] [Indexed: 01/08/2023] Open
Abstract
Effective methods to engineer the segmented, double-stranded RNA genomes of Reoviridae viruses have only recently been developed. Mammalian orthoreoviruses (MRV) and bluetongue virus (BTV) can be recovered from entirely recombinant reagents, significantly improving the capacity to study the replication, pathogenesis, and transmission of these viruses. Conversely, rotaviruses (RVs), which are the major etiological agent of severe gastroenteritis in infants and children, have thus far only been modified using single-segment replacement methods. Reoviridae reverse genetics techniques universally rely on site-specific initiation of transcription by T7 RNA polymerase to generate the authentic 5' end of recombinant RNA segments, but they vary in how the RNAs are introduced into cells: recombinant BTV is recovered by transfection of in vitro transcribed RNAs, whereas recombinant MRV and RV RNAs are transcribed intracellularly from transfected plasmid cDNAs. Additionally, several parameters have been identified in each system that are essential for recombinant virus recovery. Generating recombinant BTV requires the use of 5' capped RNAs and is enhanced by multiple rounds of RNA transfection, suggesting that translation of viral proteins is likely the rate-limiting step. For RV, the efficiency of recovery is almost entirely dependent on the strength of the selection mechanism used to isolate the single-segment recombinant RV from the unmodified helper virus. The reverse genetics methods for BTV and RV are presented and compared to the previously described MRV methods. Analysis and comparison of each method suggest several key lines of research that might lead to a reverse genetics system for RV, analogous to those used for MRV and BTV.
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Affiliation(s)
- Shane D Trask
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-8026, USA
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Ogden KM, Ramanathan HN, Patton JT. Mutational analysis of residues involved in nucleotide and divalent cation stabilization in the rotavirus RNA-dependent RNA polymerase catalytic pocket. Virology 2012; 431:12-20. [PMID: 22664357 DOI: 10.1016/j.virol.2012.05.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Revised: 05/03/2012] [Accepted: 05/09/2012] [Indexed: 12/20/2022]
Abstract
The rotavirus RNA-dependent RNA polymerase (RdRp), VP1, contains canonical RdRp motifs and a priming loop that is hypothesized to undergo conformational rearrangements during RNA synthesis. In the absence of viral core shell protein VP2, VP1 fails to interact stably with divalent cations or nucleotides and has a retracted priming loop. To identify residues of potential import to nucleotide and divalent cation stabilization, we aligned VP1 of divergent rotaviruses and the structural homolog reovirus λ3. VP1 mutants were engineered and characterized for RNA synthetic capacity in vitro. Conserved aspartic acids in RdRp motifs A and C and arginines in motif F that likely stabilize divalent cations and nucleotides were required for efficient RNA synthesis. Mutation of individual priming loop residues diminished or enhanced RNA synthesis efficiency without obviating the need for VP2, which suggests that this structure serves as a dynamic regulatory element that links RdRp activity to particle assembly.
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Affiliation(s)
- Kristen M Ogden
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-8026, USA
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Trask SD, Ogden KM, Patton JT. Interactions among capsid proteins orchestrate rotavirus particle functions. Curr Opin Virol 2012; 2:373-9. [PMID: 22595300 DOI: 10.1016/j.coviro.2012.04.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Revised: 04/23/2012] [Accepted: 04/24/2012] [Indexed: 11/16/2022]
Abstract
Rotaviruses are members of the Reoviridae family of non-enveloped viruses and important etiologic agents of acute gastroenteritis in infants and young children. In recent years, high-resolution structures of triple-layered rotavirus virions and the constituent proteins have provided valuable insights into functions. Of note, structural studies have revealed the position of the viral RNA-dependent RNA polymerase, VP1, within the inner capsid, which in turn provides clues about the location of the viral capping machinery and the route of viral transcript egress. Mechanisms by which the viral spike protein, VP4, mediates receptor binding and membrane penetration have also been aided by high-resolution structural studies. Future work may serve to fill the remaining gaps in understanding of rotavirus particle structure and function.
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Affiliation(s)
- Shane D Trask
- Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-8026, USA
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Genetic divergence of rotavirus nonstructural protein 4 results in distinct serogroup-specific viroporin activity and intracellular punctate structure morphologies. J Virol 2012; 86:4921-34. [PMID: 22357281 DOI: 10.1128/jvi.06759-11] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Nonstructural protein 4 (NSP4) viroporin activity is critical for the replication and assembly of serogroup A rotavirus (RVA); however, the dramatic primary sequence divergence of NSP4s across serogroups raises the possibility that viroporin activity is not a common feature among RVs. We tested for NSP4 viroporin activity from divergent strains, including RVA (EC and Ty-1), RVB (IDIR), and RVC (Cowden). Canonical viroporin motifs were identified in RVA, RVB, and RVC NSP4s, but the arrangement of basic residues and the amphipathic α-helices was substantially different between serogroups. Using Escherichia coli and mammalian cell expression, we showed that each NSP4 tested had viroporin activity, but serogroup-specific viroporin phenotypes were identified. Only mammalian RVA and RVC NSP4s induced BL21-pLysS E. coli cell lysis, a classical viroporin activity assay. In contrast, RVA, RVB, and RVC NSP4 expression was universally cytotoxic to E. coli and disrupted reduction-oxidation activities, as measured by a new redox dye assay. In mammalian cells, RVB and RVC NSP4s were initially localized in the endoplasmic reticulum (ER) and trafficked into punctate structures that were mutually exclusive with RVA NSP4. The punctate structures partially localized to the ER-Golgi intermediate compartment (ERGIC) but primarily colocalized with punctate LC3, a marker for autophagosomes. Similar to RVA NSP4, expression of RVB and RVC NSP4s significantly elevated cytosolic calcium levels, demonstrating that despite strong primary sequence divergence, RV NSP4 has maintained viroporin activity across serogroups A to C. These data suggest that elevated cytosolic calcium is a common critical process for all rotavirus strains.
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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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