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Urayama SI, Fukudome A, Hirai M, Okumura T, Nishimura Y, Takaki Y, Kurosawa N, Koonin EV, Krupovic M, Nunoura T. Double-stranded RNA sequencing reveals distinct riboviruses associated with thermoacidophilic bacteria from hot springs in Japan. Nat Microbiol 2024; 9:514-523. [PMID: 38233646 PMCID: PMC10847044 DOI: 10.1038/s41564-023-01579-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 12/08/2023] [Indexed: 01/19/2024]
Abstract
Metatranscriptome sequencing expanded the known diversity of the bacterial RNA virome, suggesting that additional riboviruses infecting bacterial hosts remain to be discovered. Here we employed double-stranded RNA sequencing to recover complete genome sequences of two ribovirus groups from acidic hot springs in Japan. One group, denoted hot spring riboviruses (HsRV), consists of viruses with distinct RNA-directed RNA polymerases (RdRPs) that seem to be intermediates between typical ribovirus RdRPs and viral reverse transcriptases. This group forms a distinct phylum, Artimaviricota, or even kingdom within the realm Riboviria. We identified viruses encoding HsRV-like RdRPs in marine water, river sediments and salt marshes, indicating that this group is widespread beyond extreme ecosystems. The second group, denoted hot spring partiti-like viruses (HsPV), forms a distinct branch within the family Partitiviridae. The genome architectures of HsRV and HsPV and their identification in bacteria-dominated habitats suggest that these viruses infect thermoacidophilic bacteria.
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Affiliation(s)
- Syun-Ichi Urayama
- Department of Life and Environmental Sciences, Laboratory of Fungal Interaction and Molecular Biology (donated by IFO), University of Tsukuba, Tsukuba, Japan.
- Microbiology Research Center for Sustainability (MiCS), University of Tsukuba, Tsukuba, Japan.
| | - Akihito Fukudome
- Howard Hughes Medical Institute, Department of Biology and Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - Miho Hirai
- Super-cutting-edge Grand and Advanced Research (SUGAR) Program, Japan Agency for Marine Science and Technology (JAMSTEC), Yokosuka, Japan
| | - Tomoyo Okumura
- Marine Core Research Institute, Kochi University, Nankoku, Kochi, Japan
| | - Yosuke Nishimura
- Research Center for Bioscience and Nanoscience (CeBN), JAMSTEC, Yokosuka, Japan
| | - Yoshihiro Takaki
- Super-cutting-edge Grand and Advanced Research (SUGAR) Program, Japan Agency for Marine Science and Technology (JAMSTEC), Yokosuka, Japan
| | - Norio Kurosawa
- Faculty of Science and Engineering, Soka University, Hachioji, Japan
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | - Mart Krupovic
- Institut Pasteur, Université Paris Cité, Archaeal Virology Unit, Paris, France
| | - Takuro Nunoura
- Research Center for Bioscience and Nanoscience (CeBN), JAMSTEC, Yokosuka, Japan
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2
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Heymann JB. Structural Studies of Bacteriophage Φ6 and Its Transformations during Its Life Cycle. Viruses 2023; 15:2404. [PMID: 38140645 PMCID: PMC10747372 DOI: 10.3390/v15122404] [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: 10/24/2023] [Revised: 12/01/2023] [Accepted: 12/04/2023] [Indexed: 12/24/2023] Open
Abstract
From the first isolation of the cystovirus bacteriophage Φ6 from Pseudomonas syringae 50 years ago, we have progressed to a better understanding of the structure and transformations of many parts of the virion. The three-layered virion, encapsulating the tripartite double-stranded RNA (dsRNA) genome, breaches the cell envelope upon infection, generates its own transcripts, and coopts the bacterial machinery to produce its proteins. The generation of a new virion starts with a procapsid with a contracted shape, followed by the packaging of single-stranded RNA segments with concurrent expansion of the capsid, and finally replication to reconstitute the dsRNA genome. The outer two layers are then added, and the fully formed virion released by cell lysis. Most of the procapsid structure, composed of the proteins P1, P2, P4, and P7 is now known, as well as its transformations to the mature, packaged nucleocapsid. The outer two layers are less well-studied. One additional study investigated the binding of the host protein YajQ to the infecting nucleocapsid, where it enhances the transcription of the large RNA segment that codes for the capsid proteins. Finally, I relate the structural aspects of bacteriophage Φ6 to those of other dsRNA viruses, noting the similarities and differences.
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Affiliation(s)
- J. Bernard Heymann
- National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, 50 South Dr., Bethesda, MD 20892, USA; ; Tel.: +1-301-846-6924
- National Cryo-EM Program, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21701, USA
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3
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Mäntynen S, Salomaa MM, Poranen MM. Diversity and Current Classification of dsRNA Bacteriophages. Viruses 2023; 15:2154. [PMID: 38005832 PMCID: PMC10674327 DOI: 10.3390/v15112154] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 10/11/2023] [Accepted: 10/22/2023] [Indexed: 11/26/2023] Open
Abstract
Half a century has passed since the discovery of Pseudomonas phage phi6, the first enveloped dsRNA bacteriophage to be isolated. It remained the sole known dsRNA phage for a quarter of a century and the only recognised member of the Cystoviridae family until the year 2018. After the initial discovery of phi6, additional dsRNA phages have been isolated from globally distant locations and identified in metatranscriptomic datasets, suggesting that this virus type is more ubiquitous in nature than previously acknowledged. Most identified dsRNA phages infect Pseudomonas strains and utilise either pilus or lipopolysaccharide components of the host as the primary receptor. In addition to the receptor-mediated strictly lytic lifestyle, an alternative persistent infection strategy has been described for some dsRNA phages. To date, complete genome sequences of fourteen dsRNA phage isolates are available. Despite the high sequence diversity, similar sets of genes can typically be found in the genomes of dsRNA phages, suggesting shared evolutionary trajectories. This review provides a brief overview of the recognised members of the Cystoviridae virus family and related dsRNA phage isolates, outlines the current classification of dsRNA phages, and discusses their relationships with eukaryotic RNA viruses.
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Affiliation(s)
- Sari Mäntynen
- Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, 00014 Helsinki, Finland; (M.M.S.); (M.M.P.)
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4
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Urayama SI, Fukudome A, Hirai M, Okumura T, Nishimura Y, Takaki Y, Kurosawa N, Koonin EV, Krupovic M, Nunoura T. Distinct groups of RNA viruses associated with thermoacidophilic bacteria. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.02.547447. [PMID: 37790367 PMCID: PMC10542131 DOI: 10.1101/2023.07.02.547447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Recent massive metatranscriptome mining substantially expanded the diversity of the bacterial RNA virome, suggesting that additional groups of riboviruses infecting bacterial hosts remain to be discovered. We employed full length double-stranded (ds) RNA sequencing for identification of riboviruses associated with microbial consortia dominated by bacteria and archaea in acidic hot springs in Japan. Whole sequences of two groups of multisegmented riboviruses genomes were obtained. One group, which we denoted hot spring riboviruses (HsRV), consists of unusual viruses with distinct RNA-dependent RNA polymerases (RdRPs) that seem to be intermediates between typical ribovirus RdRPs and viral reverse transcriptases. We also identified viruses encoding HsRV-like RdRPs in moderate aquatic environments, including marine water, river sediments and salt marsh, indicating that this previously overlooked ribovirus group is not restricted to the extreme ecosystem. The HsRV-like viruses are candidates for a distinct phylum or even kingdom within the viral realm Riboviria. The second group, denoted hot spring partiti-like viruses (HsPV), is a distinct branch within the family Partitiviridae. All genome segments in both these groups of viruses display the organization typical of bacterial riboviruses, where multiple open reading frames encoding individual proteins are preceded by ribosome-binding sites. Together with the identification in bacteria-dominated habitats, this genome architecture indicates that riboviruses of these distinct groups infect thermoacidophilic bacterial hosts.
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Affiliation(s)
- Syun-ichi Urayama
- Department of Life and Environmental Sciences, Laboratory of Fungal Interaction and Molecular Biology, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan
- Microbiology Research Center for Sustainability (MiCS), University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan
| | - Akihito Fukudome
- Howard Hughes Medical Institute, Department of Biology and Department of Molecular and Cellular Biochemistry, Indiana Univeristy, Bloomington, IN, USA
| | - Miho Hirai
- Super-cutting-edge Grand and Advanced Research (SUGAR) Program, Japan Agency for Marine Science and Technology (JAMSTEC), 2–15 Natsushima-cho, Yokosuka, Kanagawa 237–0061, Japan
| | - Tomoyo Okumura
- Marine Core Research Institute, Kochi University, 200 Otsu, Monobe, Nankoku City, Kochi, 783-8502, Japan
| | - Yosuke Nishimura
- Research Center for Bioscience and Nanoscience (CeBN), JAMSTEC, 2–15 Natsushima-cho, Yokosuka, Kanagawa 237–0061, Japan
| | - Yoshihiro Takaki
- Super-cutting-edge Grand and Advanced Research (SUGAR) Program, Japan Agency for Marine Science and Technology (JAMSTEC), 2–15 Natsushima-cho, Yokosuka, Kanagawa 237–0061, Japan
| | - Norio Kurosawa
- Department of Science and Engineering for Sustainable Innovation, Faculty of Science and Engineering, Soka University, Hachioji 192-8577, Japan
| | - Eugene V. Koonin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD, USA
| | - Mart Krupovic
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Archaeal Virology Unit, Paris, France
| | - Takuro Nunoura
- Research Center for Bioscience and Nanoscience (CeBN), JAMSTEC, 2–15 Natsushima-cho, Yokosuka, Kanagawa 237–0061, Japan
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5
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Villan Larios DC, Diaz Reyes BM, Pirovani CP, Loguercio LL, Santos VC, Góes-Neto A, Fonseca PLC, Aguiar ERGR. Exploring the Mycovirus Universe: Identification, Diversity, and Biotechnological Applications. J Fungi (Basel) 2023; 9:jof9030361. [PMID: 36983529 PMCID: PMC10052124 DOI: 10.3390/jof9030361] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 03/10/2023] [Accepted: 03/11/2023] [Indexed: 03/18/2023] Open
Abstract
Viruses that infect fungi are known as mycoviruses and are characterized by the lack of an extracellular phase. In recent years, the advances on nucleic acids sequencing technologies have led to a considerable increase in the number of fungi-infecting viral species described in the literature, with a special interest in assessing potential applications as fungal biocontrol agents. In the present study, we performed a comprehensive review using Scopus, Web of Science, and PubMed databases to mine mycoviruses data to explore their molecular features and their use in biotechnology. Our results showed the existence of 267 mycovirus species, of which 189 are recognized by the International Committee on Taxonomy of Viruses (ICTV). The majority of the mycoviruses identified have a dsRNA genome (38.6%), whereas the Botourmiaviridae (ssRNA+) alone represents 14% of all mycoviruses diversity. Regarding fungal hosts, members from the Sclerotinicaeae appeared as the most common species described to be infected by mycoviruses, with 16 different viral families identified so far. It is noteworthy that such results are directly associated with the high number of studies and strategies used to investigate the presence of viruses in members of the Sclerotinicaeae family. The knowledge about replication strategy and possible impact on fungi biology is available for only a small fraction of the mycoviruses studied, which is the main limitation for considering these elements potential targets for biotechnological applications. Altogether, our investigation allowed us to summarize the general characteristics of mycoviruses and their hosts, the consequences, and the implications of this knowledge on mycovirus–fungi interactions, providing an important source of information for future studies.
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Affiliation(s)
- Diana Carolina Villan Larios
- Department of Biological Sciences, Center for Biotechnology and Genetics, Universidade Estadual de Santa Cruz, Ilhéus 45662-900, Bahia, Brazil; (D.C.V.L.); (B.M.D.R.); (C.P.P.); (L.L.L.)
| | - Brayan Maudiel Diaz Reyes
- Department of Biological Sciences, Center for Biotechnology and Genetics, Universidade Estadual de Santa Cruz, Ilhéus 45662-900, Bahia, Brazil; (D.C.V.L.); (B.M.D.R.); (C.P.P.); (L.L.L.)
| | - Carlos Priminho Pirovani
- Department of Biological Sciences, Center for Biotechnology and Genetics, Universidade Estadual de Santa Cruz, Ilhéus 45662-900, Bahia, Brazil; (D.C.V.L.); (B.M.D.R.); (C.P.P.); (L.L.L.)
| | - Leandro Lopes Loguercio
- Department of Biological Sciences, Center for Biotechnology and Genetics, Universidade Estadual de Santa Cruz, Ilhéus 45662-900, Bahia, Brazil; (D.C.V.L.); (B.M.D.R.); (C.P.P.); (L.L.L.)
| | - Vinícius Castro Santos
- Department of Biochemistry and Immunology, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil;
| | - Aristóteles Góes-Neto
- Department of Microbiology, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil;
| | - Paula Luize Camargos Fonseca
- Department of Biological Sciences, Center for Biotechnology and Genetics, Universidade Estadual de Santa Cruz, Ilhéus 45662-900, Bahia, Brazil; (D.C.V.L.); (B.M.D.R.); (C.P.P.); (L.L.L.)
- Department of Genetics, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil
- Correspondence: (P.L.C.F.); (E.R.G.R.A.)
| | - Eric Roberto Guimarães Rocha Aguiar
- Department of Biological Sciences, Center for Biotechnology and Genetics, Universidade Estadual de Santa Cruz, Ilhéus 45662-900, Bahia, Brazil; (D.C.V.L.); (B.M.D.R.); (C.P.P.); (L.L.L.)
- Correspondence: (P.L.C.F.); (E.R.G.R.A.)
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6
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A Capsid Protein Fragment of a Fusagra-like Virus Found in Carica papaya Latex Interacts with the 50S Ribosomal Protein L17. Viruses 2023; 15:v15020541. [PMID: 36851755 PMCID: PMC9961563 DOI: 10.3390/v15020541] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 02/06/2023] [Accepted: 02/13/2023] [Indexed: 02/17/2023] Open
Abstract
Papaya sticky disease is caused by the association of a fusagra-like and an umbra-like virus, named papaya meleira virus (PMeV) and papaya meleira virus 2 (PMeV2), respectively. Both viral genomes are encapsidated in particles formed by the PMeV ORF1 product, which has the potential to encode a protein with 1563 amino acids (aa). However, the structural components of the viral capsid are unknown. To characterize the structural proteins of PMeV and PMeV2, virions were purified from Carica papaya latex. SDS-PAGE analysis of purified virus revealed two major proteins of ~40 kDa and ~55 kDa. Amino-terminal sequencing of the ~55 kDa protein and LC-MS/MS of purified virions indicated that this protein starts at aa 263 of the deduced ORF1 product as a result of either degradation or proteolytic processing. A yeast two-hybrid assay was used to identify Arabidopsis proteins interacting with two PMeV ORF1 product fragments (aa 321-670 and 961-1200). The 50S ribosomal protein L17 (AtRPL17) was identified as potentially associated with modulated translation-related proteins. In plant cells, AtRPL17 co-localized and interacted with the PMeV ORF1 fragments. These findings support the hypothesis that the interaction between PMeV/PMeV2 structural proteins and RPL17 is important for virus-host interactions.
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7
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Desselberger U. 14th International dsRNA Virus Symposium, Banff, Alberta, Canada, 10-14 October 2022. Virus Res 2023; 324:199032. [PMID: 36584760 DOI: 10.1016/j.virusres.2022.199032] [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: 11/30/2022] [Revised: 12/23/2022] [Accepted: 12/24/2022] [Indexed: 12/29/2022]
Abstract
This triennial International dsRNA Virus Symposium covered original data which have accrued during the most recent five years. In detail, the genomic diversity of these viruses continued to be explored; various structure-function studies were carried out using reverse genetics and biophysical techniques; intestinal organoids proved to be very suitable for special pathogenesis studies; and the potential of next generation rotavirus vaccines including use of rotavirus recombinants as vectored vaccine candidates was explored. 'Non-lytic release of enteric viruses in cloaked vesicles' was the topic of the keynote lecture by Nihal Altan-Bonnet, NIH, Bethesda, USA. The Jean Cohen lecturer of this meeting was Polly Roy, London School of Hygiene and Tropical Medicine, who spoke on aspects of the replication cycle of bluetongue viruses, and how some of the data are similar to details of rotavirus replication.
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Affiliation(s)
- Ulrich Desselberger
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, U.K..
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8
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Procházková M, Füzik T, Grybchuk D, Yurchenko V, Plevka P. Virion structure of Leishmania RNA virus 1. Virology 2022; 577:149-154. [PMID: 36371873 DOI: 10.1016/j.virol.2022.09.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 09/29/2022] [Indexed: 11/05/2022]
Abstract
The presence of Leishmania RNA virus 1 (LRV1) enables Leishmania protozoan parasites to cause more severe disease than the virus-free strains. The structure of LRV1 virus-like particles has been determined previously, however, the structure of the LRV1 virion has not been characterized. Here we used cryo-electron microscopy and single-particle reconstruction to determine the structures of the LRV1 virion and empty particle isolated from Leishmania guyanensis to resolutions of 4.0 Å and 3.6 Å, respectively. The capsid of LRV1 is built from sixty dimers of capsid proteins organized with icosahedral symmetry. RNA genomes of totiviruses are replicated inside the virions by RNA polymerases expressed as C-terminal extensions of a sub-population of capsid proteins. Most of the virions probably contain one or two copies of the RNA polymerase, however, the location of the polymerase domains in LRV1 capsid could not be identified, indicating that it varies among particles. Importance. Every year over 200 000 people contract leishmaniasis and more than five hundred people die of the disease. The mucocutaneous form of leishmaniasis produces lesions that can destroy the mucous membranes of the nose, mouth, and throat. Leishmania parasites carrying Leishmania RNA virus 1 (LRV1) are predisposed to cause aggravated symptoms in the mucocutaneous form of leishmaniasis. Here, we present the structure of the LRV1 virion determined using cryo-electron microscopy.
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Affiliation(s)
- Michaela Procházková
- Central European Institute of Technology, Masaryk University, Kamenice 753/5, Brno, 625 00, Czech Republic
| | - Tibor Füzik
- Central European Institute of Technology, Masaryk University, Kamenice 753/5, Brno, 625 00, Czech Republic
| | - Danyil Grybchuk
- Central European Institute of Technology, Masaryk University, Kamenice 753/5, Brno, 625 00, Czech Republic
| | - Vyacheslav Yurchenko
- Life Science Research Centre, Faculty of Science, University of Ostrava, Chittussiho 10, Ostrava, 710 00, Czech Republic
| | - Pavel Plevka
- Central European Institute of Technology, Masaryk University, Kamenice 753/5, Brno, 625 00, Czech Republic.
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9
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Grybchuk D, Procházková M, Füzik T, Konovalovas A, Serva S, Yurchenko V, Plevka P. Structures of L-BC virus and its open particle provide insight into Totivirus capsid assembly. Commun Biol 2022; 5:847. [PMID: 35986212 PMCID: PMC9391438 DOI: 10.1038/s42003-022-03793-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 08/03/2022] [Indexed: 11/18/2022] Open
Abstract
L-BC virus persists in the budding yeast Saccharomyces cerevisiae, whereas other viruses from the family Totiviridae infect a diverse group of organisms including protists, fungi, arthropods, and vertebrates. The presence of totiviruses alters the fitness of the host organisms, for example, by maintaining the killer system in yeast or increasing the virulence of Leishmania guyanensis. Despite the importance of totiviruses for their host survival, there is limited information about Totivirus structure and assembly. Here we used cryo-electron microscopy to determine the structure of L-BC virus to a resolution of 2.9 Å. The L-BC capsid is organized with icosahedral symmetry, with each asymmetric unit composed of two copies of the capsid protein. Decamers of capsid proteins are stabilized by domain swapping of the C-termini of subunits located around icosahedral fivefold axes. We show that capsids of 9% of particles in a purified L-BC sample were open and lacked one decamer of capsid proteins. The existence of the open particles together with domain swapping within a decamer provides evidence that Totiviridae capsids assemble from the decamers of capsid proteins. Furthermore, the open particles may be assembly intermediates that are prepared for the incorporation of the virus (+) strand RNA. A 2.9 Å resolution structure of the L-BC virus provides insight into the contacts between capsid proteins and the mechanism of capsid assembly.
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10
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Shimura H, Kim H, Matsuzawa A, Akino S, Masuta C. Coat protein of partitiviruses isolated from mycorrhizal fungi functions as an RNA silencing suppressor in plants and fungi. Sci Rep 2022; 12:7855. [PMID: 35551196 PMCID: PMC9098641 DOI: 10.1038/s41598-022-11403-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 04/19/2022] [Indexed: 12/11/2022] Open
Abstract
Orchid seeds depend on colonization by orchid mycorrhizal (OM) fungi for their germination; therefore, the orchids and OM fungi have long maintained a close relationship (e.g., formation of the hyphal mass structure, peloton) during their evolution. In the present study, we isolated new partitiviruses from OM fungi; partitivirus were separately found in different subcultures from the same fungi. Partitiviruses have been believed to lack an RNA silencing suppressor (RSS), which is generally associated with viral pathogenicity, because most partitiviruses isolated so far are latent in both plants and fungi. However, we found that the coat protein (CP) of our partitiviruses indeed had RSS activity, which differed among the virus isolates from OM fungi; one CP showed RSS activity in both plants and fungi, while another CP showed no activity. The family Partitiviridae include viruses isolated from plants and fungi, and it has been suggested that these viruses may occasionally be transmitted between plant and fungal hosts. Given that there are several reports showing that viruses can adapt to nonhost using strong RSS, we here discussed the idea that partitiviruses may be better able to migrate between the orchid and fungus probably through the pelotons formed in the orchid cells, if host RNA silencing is suppressed by partitivirus RSS.
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Affiliation(s)
- Hanako Shimura
- Research Faculty of Agriculture, Hokkaido University, Kita-ku, Kita 9, Nishi 9, Sapporo, 060-8589, Japan.
| | - Hangil Kim
- Research Faculty of Agriculture, Hokkaido University, Kita-ku, Kita 9, Nishi 9, Sapporo, 060-8589, Japan
| | - Akihiko Matsuzawa
- Research Faculty of Agriculture, Hokkaido University, Kita-ku, Kita 9, Nishi 9, Sapporo, 060-8589, Japan
| | - Seishi Akino
- Research Faculty of Agriculture, Hokkaido University, Kita-ku, Kita 9, Nishi 9, Sapporo, 060-8589, Japan
| | - Chikara Masuta
- Research Faculty of Agriculture, Hokkaido University, Kita-ku, Kita 9, Nishi 9, Sapporo, 060-8589, Japan.
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11
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Yang J, Peng Y, Kong W. Identification and complete genome sequence of mulberry cryptic virus 1. Arch Virol 2022; 167:687-690. [PMID: 34985553 DOI: 10.1007/s00705-021-05350-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 11/18/2021] [Indexed: 11/24/2022]
Abstract
A cryptic virus, named mulberry cryptic virus 1 (MuCV1), was identified in a mulberry (Morus alba) transcriptome dataset and confirmed using RACE methods. The genome of MuCV1 is composed of two double-stranded RNAs, 1605 bp and 1627 bp in size, encoding an RNA-dependent RNA polymerase (RdRp) and a coat protein (CP), respectively. The 5'-AGAAUU-3' sequence in the 5' untranslated region was conserved in the two dsRNAs. Sequence comparisons and phylogenetic analysis based on RdRp and CP sequences both indicated that MuCV1 is a deltapartitivirus (family Partitiviridae).
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Affiliation(s)
- Jinhong Yang
- Shaanxi Key Laboratory of Sericulture, Ankang University, Shaanxi, 725099, China
| | - Yunwu Peng
- Shaanxi Key Laboratory of Sericulture, Ankang University, Shaanxi, 725099, China
| | - Weiqing Kong
- Shaanxi Key Laboratory of Sericulture, Ankang University, Shaanxi, 725099, China.
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12
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Byrne M, Kashyap A, Esquirol L, Ranson N, Sainsbury F. The structure of a plant-specific partitivirus capsid reveals a unique coat protein domain architecture with an intrinsically disordered protrusion. Commun Biol 2021; 4:1155. [PMID: 34615994 PMCID: PMC8494798 DOI: 10.1038/s42003-021-02687-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Accepted: 09/17/2021] [Indexed: 11/22/2022] Open
Abstract
Persistent plant viruses may be the most common viruses in wild plants. A growing body of evidence for mutualism between such viruses and their hosts, suggests that they play an important role in ecology and agriculture. Here we present the capsid structure of a plant-specific partitivirus, Pepper cryptic virus 1, at 2.9 Å resolution by Cryo-EM. Structural features, including the T = 1 arrangement of 60 coat protein dimers, are shared with fungal partitiviruses and the picobirnavirus lineage of dsRNA viruses. However, the topology of the capsid is markedly different with protrusions emanating from, and partly comprising, the binding interface of coat protein dimers. We show that a disordered region at the apex of the protrusion is not required for capsid assembly and represents a hypervariable site unique to, and characteristic of, the plant-specific partitiviruses. These results suggest a structural basis for the acquisition of additional functions by partitivirus coat proteins that enables mutualistic relationships with diverse plant hosts.
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Affiliation(s)
- Matthew Byrne
- Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK.
| | - Aseem Kashyap
- Centre for Cell Factories and Biopolymers, Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, 4111, Australia
| | - Lygie Esquirol
- Centre for Cell Factories and Biopolymers, Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, 4111, Australia
| | - Neil Ranson
- Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Frank Sainsbury
- Centre for Cell Factories and Biopolymers, Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, 4111, Australia.
- Synthetic Biology Future Science Platform, Commonwealth Scientific and Industrial Research Organization (CSIRO), Brisbane, QLD, 4001, Australia.
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13
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Abstract
Trichomonas vaginalis viruses (TVVs) are double-stranded RNA (dsRNA) viruses that cohabitate in Trichomonas vaginalis, the causative pathogen of trichomoniasis, the most common nonviral sexually transmitted disease worldwide. Featuring an unsegmented dsRNA genome encoding a single capsid shell protein (CSP), TVVs contrast with multisegmented dsRNA viruses, such as the diarrhea-causing rotavirus, whose larger genome is split into 10 dsRNA segments encoding 5 unique capsid proteins. Trichomonas vaginalis, the causative pathogen for the most common nonviral sexually transmitted infection worldwide, is itself frequently infected with one or more of the four types of small double-stranded RNA (dsRNA) Trichomonas vaginalis viruses (TVV1 to 4, genus Trichomonasvirus, family Totiviridae). Each TVV encloses a nonsegmented genome within a single-layered capsid and replicates entirely intracellularly, like many dsRNA viruses, and unlike those in the Reoviridae family. Here, we have determined the structure of TVV2 by cryo-electron microscopy (cryoEM) at 3.6 Å resolution and derived an atomic model of its capsid. TVV2 has an icosahedral, T = 2*, capsid comprised of 60 copies of the icosahedral asymmetric unit (a dimer of the two capsid shell protein [CSP] conformers, CSP-A and CSP-B), typical of icosahedral dsRNA virus capsids. However, unlike the robust CSP-interlocking interactions such as the use of auxiliary “clamping” proteins among Reoviridae, only lateral CSP interactions are observed in TVV2, consistent with an assembly strategy optimized for TVVs’ intracellular-only replication cycles within their protozoan host. The atomic model reveals both a mostly negatively charged capsid interior, which is conducive to movement of the loosely packed genome, and channels at the 5-fold vertices, which we suggest as routes of mRNA release during transcription. Structural comparison of TVV2 to the Saccharomyces cerevisiae L-A virus reveals a conserved helix-rich fold within the CSP and putative guanylyltransferase domain along the capsid exterior, suggesting conserved mRNA maintenance strategies among Totiviridae. This first atomic structure of a TVV provides a framework to guide future biochemical investigations into the interplay between Trichomonas vaginalis and its viruses.
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Structure Unveils Relationships between RNA Virus Polymerases. Viruses 2021; 13:v13020313. [PMID: 33671332 PMCID: PMC7922027 DOI: 10.3390/v13020313] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 02/14/2021] [Accepted: 02/15/2021] [Indexed: 12/30/2022] Open
Abstract
RNA viruses are the fastest evolving known biological entities. Consequently, the sequence similarity between homologous viral proteins disappears quickly, limiting the usability of traditional sequence-based phylogenetic methods in the reconstruction of relationships and evolutionary history among RNA viruses. Protein structures, however, typically evolve more slowly than sequences, and structural similarity can still be evident, when no sequence similarity can be detected. Here, we used an automated structural comparison method, homologous structure finder, for comprehensive comparisons of viral RNA-dependent RNA polymerases (RdRps). We identified a common structural core of 231 residues for all the structurally characterized viral RdRps, covering segmented and non-segmented negative-sense, positive-sense, and double-stranded RNA viruses infecting both prokaryotic and eukaryotic hosts. The grouping and branching of the viral RdRps in the structure-based phylogenetic tree follow their functional differentiation. The RdRps using protein primer, RNA primer, or self-priming mechanisms have evolved independently of each other, and the RdRps cluster into two large branches based on the used transcription mechanism. The structure-based distance tree presented here follows the recently established RdRp-based RNA virus classification at genus, subfamily, family, order, class and subphylum ranks. However, the topology of our phylogenetic tree suggests an alternative phylum level organization.
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15
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Abstract
Twelve million people worldwide suffer from leishmaniasis, resulting in more than 30 thousand deaths annually. The disease has several variants that differ in their symptoms. Leishmania parasites cause a variety of symptoms, including mucocutaneous leishmaniasis, which results in the destruction of the mucous membranes of the nose, mouth, and throat. The species of Leishmania carrying Leishmania RNA virus 1 (LRV1), from the family Totiviridae, are more likely to cause severe disease and are less sensitive to treatment than those that do not contain the virus. Although the importance of LRV1 for the severity of leishmaniasis was discovered a long time ago, the structure of the virus remained unknown. Here, we present a cryo-electron microscopy reconstruction of the virus-like particle of LRV1 determined to a resolution of 3.65 Å. The capsid has icosahedral symmetry and is formed by 120 copies of a capsid protein assembled in asymmetric dimers. RNA genomes of viruses from the family Totiviridae are synthetized, but not capped at the 5′ end, by virus RNA polymerases. To protect viral RNAs from degradation, capsid proteins of the L-A totivirus cleave the 5′ caps of host mRNAs, creating decoys to overload the cellular RNA quality control system. Capsid proteins of LRV1 form positively charged clefts, which may be the cleavage sites for the 5′ cap of Leishmania mRNAs. The putative RNA binding site of LRV1 is distinct from that of the related L-A virus. The structure of the LRV1 capsid enables the rational design of compounds targeting the putative decapping site. Such inhibitors may be developed into a treatment for mucocutaneous leishmaniasis caused by LRV1-positive species of Leishmania. IMPORTANCE Twelve million people worldwide suffer from leishmaniasis, resulting in more than 30 thousand deaths annually. The disease has several variants that differ in their symptoms. The mucocutaneous form, which leads to disintegration of the nasal septum, lips, and palate, is caused predominantly by Leishmania parasites carrying Leishmania RNA virus 1 (LRV1). Here, we present the structure of the LRV1 capsid determined using cryo-electron microscopy. Capsid proteins of a related totivirus, L-A virus, protect viral RNAs from degradation by cleaving the 5′ caps of host mRNAs. Capsid proteins of LRV1 may have the same function. We show that the LRV1 capsid contains positively charged clefts that may be sites for the cleavage of mRNAs of Leishmania cells. The structure of the LRV1 capsid enables the rational design of compounds targeting the putative mRNA cleavage site. Such inhibitors may be used as treatments for mucocutaneous leishmaniasis.
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16
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Cryo-electron Microscopy Structure, Assembly, and Mechanics Show Morphogenesis and Evolution of Human Picobirnavirus. J Virol 2020; 94:JVI.01542-20. [PMID: 32938763 DOI: 10.1128/jvi.01542-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 09/08/2020] [Indexed: 12/17/2022] Open
Abstract
Despite their diversity, most double-stranded-RNA (dsRNA) viruses share a specialized T=1 capsid built from dimers of a single protein that provides a platform for genome transcription and replication. This ubiquitous capsid remains structurally undisturbed throughout the viral cycle, isolating the genome to avoid triggering host defense mechanisms. Human picobirnavirus (hPBV) is a dsRNA virus frequently associated with gastroenteritis, although its pathogenicity is yet undefined. Here, we report the cryo-electron microscopy (cryo-EM) structure of hPBV at 2.6-Å resolution. The capsid protein (CP) is arranged in a single-shelled, ∼380-Å-diameter T=1 capsid with a rough outer surface similar to that of dsRNA mycoviruses. The hPBV capsid is built of 60 quasisymmetric CP dimers (A and B) stabilized by domain swapping, and only the CP-A N-terminal basic region interacts with the packaged nucleic acids. hPBV CP has an α-helical domain with a fold similar to that of fungal partitivirus CP, with many domain insertions in its C-terminal half. In contrast to dsRNA mycoviruses, hPBV has an extracellular life cycle phase like complex reoviruses, which indicates that its own CP probably participates in cell entry. Using an in vitro reversible assembly/disassembly system of hPBV, we isolated tetramers as possible assembly intermediates. We used atomic force microscopy to characterize the biophysical properties of hPBV capsids with different cargos (host nucleic acids or proteins) and found that the CP N-terminal segment not only is involved in nucleic acid interaction/packaging but also modulates the mechanical behavior of the capsid in conjunction with the cargo.IMPORTANCE Despite intensive study, human virus sampling is still sparse, especially for viruses that cause mild or asymptomatic disease. Human picobirnavirus (hPBV) is a double-stranded-RNA virus, broadly dispersed in the human population, but its pathogenicity is uncertain. Here, we report the hPBV structure derived from cryo-electron microscopy (cryo-EM) and reconstruction methods using three capsid protein variants (of different lengths and N-terminal amino acid compositions) that assemble as virus-like particles with distinct properties. The hPBV near-atomic structure reveals a quasisymmetric dimer as the structural subunit and tetramers as possible assembly intermediates that coassemble with nucleic acids. Our structural studies and atomic force microscopy analyses indicate that hPBV capsids are potentially excellent nanocages for gene therapy and targeted drug delivery in humans.
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Jacquat AG, Theumer MG, Cañizares MC, Debat HJ, Iglesias J, García Pedrajas MD, Dambolena JS. A Survey of Mycoviral Infection in Fusarium spp. Isolated from Maize and Sorghum in Argentina Identifies the First Mycovirus from Fusarium verticillioides. Viruses 2020; 12:v12101161. [PMID: 33066620 PMCID: PMC7602464 DOI: 10.3390/v12101161] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 09/28/2020] [Accepted: 10/09/2020] [Indexed: 12/30/2022] Open
Abstract
Mycoviruses appear to be widespread in Fusarium species worldwide. The aim of this work was to identify mycoviral infections in Fusarium spp., isolated from maize and sorghum grown in Argentina, and to estimate their potential effects on the pathogenicity and toxigenesis of the host fungus towards maize. Mycoviruses were identified in 2 out of 105 isolates analyzed; Fusarium verticillioides strain Sec505 and Fusarium andiyazi strain 162. They were characterized as members of the genus Mitovirus by high-throughput sequencing and sequence analysis. The F. verticillioides mitovirus was a novel mycovirus whereas the F. andiyazi mitovirus was found to be a new strain of a previously identified mitovirus. We have named these mitoviruses, Fusarium verticillioides mitovirus 1 (FvMV1) and Fusarium andiyazi mitovirus 1 strain 162 (FaMV1-162). To our knowledge, FvMV1 is the first mycovirus reported as naturally infecting F. verticillioides, the major causal agent of ear rot and fumonisin producer in corn. Both mitoviruses exhibited 100% vertical transmission rate to microconidia. The Fa162 strain infected with FaMV1-162 did not show phenotypic alterations. In contract, F. verticillioides Sec505 infected with FvMV1 showed increased virulence as well as microconidia and fumonisin-B1 production, compared with two uninfected strains. These results suggest that FvMV1 could have a role in modulating F. verticillioides pathogenicity and toxin production worth further exploring.
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Affiliation(s)
- Andrés Gustavo Jacquat
- Facultad de Ciencias Exactas Físicas y Naturales (FCEFyN), Universidad Nacional de Córdoba (UNC), Córdoba 5000, Argentina;
- Instituto Multidisciplinario de Biología Vegetal (IMBIV), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Avenida Vélez Sarsfield 1611, Córdoba X5016GCA, Argentina
| | - Martín Gustavo Theumer
- Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas (FCQ), Universidad Nacional de Córdoba (UNC), Córdoba 5000, Argentina;
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Haya de la Torre y Medina Allende—Ciudad Universitaria, Córdoba X5000HUA, Argentina
| | - María Carmen Cañizares
- Instituto de Hortofruticultura Subtropical y Mediterránea “La Mayora”, Universidad de Málaga, Consejo Superior de Investigaciones Científicas (IHSM—UMA—CSIC), Estación Experimental “La Mayora”, Avenida Dr. Wienberg s/n, 29750 Algarrobo-Costa, Málaga, Spain;
| | - Humberto Julio Debat
- Instituto de Patología Vegetal, Centro de Investigaciones Agropecuarias, Instituto Nacional de Tecnología Agropecuaria (IPAVE—CIAP—INTA), Camino 60 Cuadras Km 5.5, Córdoba X5020ICA, Argentina;
| | - Juliana Iglesias
- Estación Experimental Pergamino, (EEA) INTA Pergamino, Universidad Nacional Noroeste (UNNOBA), Pergamino (Buenos Aires) B2700, Argentina;
| | - María Dolores García Pedrajas
- Instituto de Hortofruticultura Subtropical y Mediterránea “La Mayora”, Universidad de Málaga, Consejo Superior de Investigaciones Científicas (IHSM—UMA—CSIC), Estación Experimental “La Mayora”, Avenida Dr. Wienberg s/n, 29750 Algarrobo-Costa, Málaga, Spain;
- Correspondence: (M.D.G.P.); (J.S.D.)
| | - José Sebastián Dambolena
- Facultad de Ciencias Exactas Físicas y Naturales (FCEFyN), Universidad Nacional de Córdoba (UNC), Córdoba 5000, Argentina;
- Instituto Multidisciplinario de Biología Vegetal (IMBIV), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Avenida Vélez Sarsfield 1611, Córdoba X5016GCA, Argentina
- Correspondence: (M.D.G.P.); (J.S.D.)
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18
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Viruses with different genome types adopt a similar strategy to pack nucleic acids based on positively charged protein domains. Sci Rep 2020; 10:5470. [PMID: 32214181 PMCID: PMC7096446 DOI: 10.1038/s41598-020-62328-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 03/02/2020] [Indexed: 11/17/2022] Open
Abstract
Capsid proteins often present a positively charged arginine-rich sequence at their terminal regions, which has a fundamental role in genome packaging and particle stability for some icosahedral viruses. These sequences show little to no conservation and are structurally dynamic such that they cannot be easily detected by common sequence or structure comparisons. As a result, the occurrence and distribution of positively charged domains across the viral universe are unknown. Based on the net charge calculation of discrete protein segments, we identified proteins containing amino acid stretches with a notably high net charge (Q > + 17), which are enriched in icosahedral viruses with a distinctive bias towards arginine over lysine. We used viral particle structural data to calculate the total electrostatic charge derived from the most positively charged protein segment of capsid proteins and correlated these values with genome charges arising from the phosphates of each nucleotide. We obtained a positive correlation (r = 0.91, p-value <0001) for a group of 17 viral families, corresponding to 40% of all families with icosahedral structures described to date. These data indicated that unrelated viruses with diverse genome types adopt a common underlying mechanism for capsid assembly based on R-arms.
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19
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Jamal A, Sato Y, Shahi S, Shamsi W, Kondo H, Suzuki N. Novel Victorivirus from a Pakistani Isolate of Alternaria alternata Lacking a Typical Translational Stop/Restart Sequence Signature. Viruses 2019; 11:E577. [PMID: 31242660 PMCID: PMC6631646 DOI: 10.3390/v11060577] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 06/19/2019] [Accepted: 06/21/2019] [Indexed: 01/27/2023] Open
Abstract
The family Totiviridae currently contains five genera Totivirus, Victorivirus, Leishmavirus, Trichomonasvirus, and Giardiavirus. Members in this family generally have a set of two-open reading frame (ORF) elements in their genome with the 5'-proximal ORF (ORF1) encoding a capsid protein (CP) and the 3'-proximal one (ORF2) for RNA-dependent RNA polymerase (RdRp). How the downstream open reading frames (ORFs) are expressed is genus-specific. All victoriviruses characterized thus far appear to use the stop/restart translation mechanism, allowing for the expression of two separate protein products from bicitronic genome-sized viral mRNA, while the totiviruses use a -1 ribosomal frame-shifting that leads to a fusion product of CP and RdRp. We report the biological and molecular characterization of a novel victorivirus termed Alternaria alternata victorivirus 1 (AalVV1) isolated from Alternaria alternata in Pakistan. The phylogenetic and molecular analyses showed AalVV1 to be distinct from previously reported victoriviruses. AalVV1 appears to have a sequence signature required for the -1 frame-shifting at the ORF1/2 junction region, rather than a stop/restart key mediator. By contrast, SDS-polyacrylamide gel electrophoresis and peptide mass fingerprinting analyses of purified virion preparations suggested the expression of two protein products, not a CP-RdRp fusion product. How these proteins are expressed is discussed in this study. Possible effects of infection by this virus were tested in two fungal species: A. alternata and RNA silencing proficient and deficient strains of Cryphonectria parasitica, a model filamentous fungus. AalVV1 showed symptomless infection in all of these fungal strains, even in the RNA silencing deficient C. parasitica strain.
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Affiliation(s)
- Atif Jamal
- Institute of Plant Science and Resources, Okayama University, Chuou 2-20-1, Kurashiki, Okayama 710-0046, Japan.
- Crop Diseases Research Institute, National Agricultural Research Centre, Park Road, Islamabad 45500, Pakistan.
| | - Yukiyo Sato
- Institute of Plant Science and Resources, Okayama University, Chuou 2-20-1, Kurashiki, Okayama 710-0046, Japan.
| | - Sabitree Shahi
- Institute of Plant Science and Resources, Okayama University, Chuou 2-20-1, Kurashiki, Okayama 710-0046, Japan.
| | - Wajeeha Shamsi
- Institute of Plant Science and Resources, Okayama University, Chuou 2-20-1, Kurashiki, Okayama 710-0046, Japan.
| | - Hideki Kondo
- Institute of Plant Science and Resources, Okayama University, Chuou 2-20-1, Kurashiki, Okayama 710-0046, Japan.
| | - Nobuhiro Suzuki
- Institute of Plant Science and Resources, Okayama University, Chuou 2-20-1, Kurashiki, Okayama 710-0046, Japan.
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20
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Petrzik K. Evolutionary forces at work in partitiviruses. Virus Genes 2019; 55:563-573. [PMID: 31230256 DOI: 10.1007/s11262-019-01680-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 06/18/2019] [Indexed: 02/07/2023]
Abstract
The family Partitiviridae consists of dsRNA viruses with genome separated into two segments and encoding replicase and capsid protein only. We examined the nucleotide diversity expressed as the ratio dN/dS of nonsynonymous and synonymous substitutions, which has been calculated for 12 representative viruses of all five genera of partitiviruses. We can state that strong purifying selection works on both the RdRp and CP genes and propose that putative positive selection occurs also on the RdRp genes in two viruses. Among the 95 evaluated viruses, wherein both segments had been sequenced, 8 viruses in betapartitiviruses and 9 in alphapartitiviruses were identified as reassortment candidates because they differ extremely in their CP identity even as they are related in terms of RdRp. Furthermore, there are indications that reassortants are present among isolates of different viruses.
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Affiliation(s)
- Karel Petrzik
- Department of Plant Virology, Institute of Plant Molecular Biology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice, Czech Republic.
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21
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Kotta-Loizou I. Mycoviruses: Past, Present, and Future. Viruses 2019; 11:v11040361. [PMID: 31010228 PMCID: PMC6520932 DOI: 10.3390/v11040361] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 04/19/2019] [Indexed: 12/19/2022] Open
Affiliation(s)
- Ioly Kotta-Loizou
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK.
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22
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Shamsi W, Sato Y, Jamal A, Shahi S, Kondo H, Suzuki N, Bhatti MF. Molecular and biological characterization of a novel botybirnavirus identified from a Pakistani isolate of Alternaria alternata. Virus Res 2019; 263:119-128. [DOI: 10.1016/j.virusres.2019.01.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 01/09/2019] [Accepted: 01/10/2019] [Indexed: 11/15/2022]
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23
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Shah UA, Kotta-Loizou I, Fitt BDL, Coutts RHA. Identification, Molecular Characterization, and Biology of a Novel Quadrivirus Infecting the Phytopathogenic Fungus Leptosphaeria biglobosa. Viruses 2018; 11:E9. [PMID: 30585188 PMCID: PMC6356713 DOI: 10.3390/v11010009] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2018] [Revised: 12/20/2018] [Accepted: 12/22/2018] [Indexed: 01/18/2023] Open
Abstract
Here we report the molecular characterisation of a novel dsRNA virus isolated from the filamentous, plant pathogenic fungus Leptosphaeria biglobosa and known to cause significant alterations to fungal pigmentation and growth and to result in hypervirulence, as illustrated by comparisons between virus-infected and -cured isogenic fungal strains. The virus forms isometric particles approximately 40⁻45 nm in diameter and has a quadripartite dsRNA genome structure with size ranges of 4.9 to 4 kbp, each possessing a single ORF. Sequence analysis of the putative proteins encoded by dsRNAs 1⁻4, termed P1⁻P4, respectively, revealed modest similarities to the amino acid sequences of equivalent proteins predicted from the nucleotide sequences of known and suspected members of the family Quadriviridae and for that reason the virus was nominated Leptosphaeria biglobosa quadrivirus-1 (LbQV-1). Sequence and phylogenetic analysis using the P3 sequence, which encodes an RdRP, revealed that LbQV-1 was most closely related to known and suspected quadriviruses and monopartite totiviruses rather than other quadripartite mycoviruses including chrysoviruses and alternaviruses. Of the remaining encoded proteins, LbQV-1 P2 and P4 are structural proteins but the function of P1 is unknown. We propose that LbQV-1 is a novel member of the family Quadriviridae.
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Affiliation(s)
- Unnati A Shah
- Department of Biological and Environmental Sciences, University of Hertfordshire, Hatfield AL10 9AB, UK.
| | - Ioly Kotta-Loizou
- Department of Biological and Environmental Sciences, University of Hertfordshire, Hatfield AL10 9AB, UK.
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK.
| | - Bruce D L Fitt
- Department of Biological and Environmental Sciences, University of Hertfordshire, Hatfield AL10 9AB, UK.
| | - Robert H A Coutts
- Department of Biological and Environmental Sciences, University of Hertfordshire, Hatfield AL10 9AB, UK.
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