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Abstract
Recently, dozens of virus structures have been solved to resolutions between 2.5 and 5.0 Å by means of electron cryomicroscopy. With these structures we are now firmly within the "atomic age" of electron cryomicroscopy, as these studies can reveal atomic details of protein and nucleic acid topology and interactions between specific residues. This improvement in resolution has been the result of direct electron detectors and image processing advances. Although enforcing symmetry facilitates reaching near-atomic resolution with fewer particle images, it unfortunately obscures some biologically interesting components of a virus. New approaches on relaxing symmetry and exploring structure dynamics and heterogeneity of viral assemblies have revealed important insights into genome packaging, virion assembly, cell entry, and other stages of the viral life cycle. In the future, novel methods will be required to reveal yet-unknown structural conformations of viruses, relevant to their biological activities. Ultimately, these results hold the promise of answering many unresolved questions linking structural diversity of viruses to their biological functions.
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Affiliation(s)
- Jason T Kaelber
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030.,National Center for Macromolecular Imaging, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030
| | - Corey F Hryc
- National Center for Macromolecular Imaging, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030.,Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, Texas 77030;
| | - Wah Chiu
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030.,National Center for Macromolecular Imaging, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030.,Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, Texas 77030;
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52
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Cryo-EM reconstruction of the Cafeteria roenbergensis virus capsid suggests novel assembly pathway for giant viruses. Sci Rep 2017; 7:5484. [PMID: 28710447 PMCID: PMC5511168 DOI: 10.1038/s41598-017-05824-w] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 06/02/2017] [Indexed: 11/09/2022] Open
Abstract
Whereas the protein composition and overall shape of several giant virus capsids have been described, the mechanism by which these large capsids assemble remains enigmatic. Here, we present a reconstruction of the capsid of Cafeteria roenbergensis virus (CroV), one of the largest viruses analyzed by cryo-electron microscopy (cryo-EM) to date. The CroV capsid has a diameter of 3,000 Å and a Triangulation number of 499. Unlike related mimiviruses, the CroV capsid is not decorated with glycosylated surface fibers, but features 30 Å-long surface protrusions that are formed by loops of the major capsid protein. Based on the orientation of capsomers in the cryo-EM reconstruction, we propose that the capsids of CroV and related giant viruses are assembled by a newly conceived assembly pathway that initiates at a five-fold vertex and continuously proceeds outwards in a spiraling fashion.
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53
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Wagstaff BA, Vladu IC, Barclay JE, Schroeder DC, Malin G, Field RA. Isolation and Characterization of a Double Stranded DNA Megavirus Infecting the Toxin-Producing Haptophyte Prymnesium parvum. Viruses 2017; 9:v9030040. [PMID: 28282930 PMCID: PMC5371795 DOI: 10.3390/v9030040] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Revised: 02/22/2017] [Accepted: 02/27/2017] [Indexed: 01/31/2023] Open
Abstract
Prymnesium parvum is a toxin-producing haptophyte that causes harmful algal blooms globally, leading to large-scale fish kills that have severe ecological and economic implications. For the model haptophyte, Emiliania huxleyi, it has been shown that large dsDNA viruses play an important role in regulating blooms and therefore biogeochemical cycling, but much less work has been done looking at viruses that infect P. parvum, or the role that these viruses may play in regulating harmful algal blooms. In this study, we report the isolation and characterization of a lytic nucleo-cytoplasmic large DNA virus (NCLDV) collected from the site of a harmful P. parvum bloom. In subsequent experiments, this virus was shown to infect cultures of Prymnesium sp. and showed phylogenetic similarity to the extended Megaviridae family of algal viruses.
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Affiliation(s)
- Ben A Wagstaff
- Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
| | - Iulia C Vladu
- Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
| | - J Elaine Barclay
- Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
| | | | - Gill Malin
- Centre for Ocean and Atmospheric Studies, School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.
| | - Robert A Field
- Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
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54
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Colson P, La Scola B, Levasseur A, Caetano-Anollés G, Raoult D. Mimivirus: leading the way in the discovery of giant viruses of amoebae. Nat Rev Microbiol 2017; 15:243-254. [PMID: 28239153 PMCID: PMC7096837 DOI: 10.1038/nrmicro.2016.197] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Acanthamoeba polyphaga mimivirus (APMV) and subsequently discovered giant viruses of amoebae challenge the previous definition of viruses and their classification. The replication cycle, structure, genomic make-up and plasticity of giant viruses differ from those of traditional viruses. They extend the definition of viruses into a broader range of biological entities, some of which are very simple and others of which have a complexity that is comparable to that of other microorganisms. Giant viruses of amoebae have virus particles as large as some microorganisms that are visible by light microscopy and that have a stunning level of complexity. Their genomes are mosaics and contain large repertoires of genes, some of which are hallmarks of cellular organisms, although the majority of which have unknown functions. Mimiviruses are associated with a specific mobilome and are parasitized by viruses that they can defend against. Several hypotheses on the ancient origin and evolutionary relationship between cellular organisms and giant viruses of amoebae have been proposed, and these topics continue to be debated. The detection of giant viruses of amoebae in humans and the study of their potential pathogenicity are emerging fields.
The discovery of the giant amoebal virus mimivirus, in 2003, opened up a new area of virology. Extended studies, including those of mimiviruses, have since revealed that these viruses have genetic, proteomic and structural features that are more complex than those of conventional viruses. The accidental discovery of the giant virus of amoeba — Acanthamoeba polyphaga mimivirus (APMV; more commonly known as mimivirus) — in 2003 changed the field of virology. Viruses were previously defined by their submicroscopic size, which probably prevented the search for giant viruses, which are visible by light microscopy. Extended studies of giant viruses of amoebae revealed that they have genetic, proteomic and structural complexities that were not thought to exist among viruses and that are comparable to those of bacteria, archaea and small eukaryotes. The giant virus particles contain mRNA and more than 100 proteins, they have gene repertoires that are broader than those of other viruses and, notably, some encode translation components. The infection cycles of giant viruses of amoebae involve virus entry by amoebal phagocytosis and replication in viral factories. In addition, mimiviruses are infected by virophages, defend against them through the mimivirus virophage resistance element (MIMIVIRE) system and have a unique mobilome. Overall, giant viruses of amoebae, including mimiviruses, marseilleviruses, pandoraviruses, pithoviruses, faustoviruses and molliviruses, challenge the definition and classification of viruses, and have increasingly been detected in humans.
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Affiliation(s)
- Philippe Colson
- Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE), Aix-Marseille University, UM63, CNRS 7278, IRD 198, INSERM 1095, Institut Hospitalo-Universitaire (IHU) - Méditerranée Infection, AP-HM, 19-21 Boulevard Jean Moulin, 13385 Marseille, France
| | - Bernard La Scola
- Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE), Aix-Marseille University, UM63, CNRS 7278, IRD 198, INSERM 1095, Institut Hospitalo-Universitaire (IHU) - Méditerranée Infection, AP-HM, 19-21 Boulevard Jean Moulin, 13385 Marseille, France
| | - Anthony Levasseur
- Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE), Aix-Marseille University, UM63, CNRS 7278, IRD 198, INSERM 1095, Institut Hospitalo-Universitaire (IHU) - Méditerranée Infection, AP-HM, 19-21 Boulevard Jean Moulin, 13385 Marseille, France
| | - Gustavo Caetano-Anollés
- Evolutionary Bioinformatics Laboratory, Department of Crop Sciences, University of Illinois, 332 National Soybean Research Center, 1101 West Peabody Drive, Urbana, Illinois 61801, USA
| | - Didier Raoult
- Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE), Aix-Marseille University, UM63, CNRS 7278, IRD 198, INSERM 1095, Institut Hospitalo-Universitaire (IHU) - Méditerranée Infection, AP-HM, 19-21 Boulevard Jean Moulin, 13385 Marseille, France
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55
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Schrad JR, Young EJ, Abrahão JS, Cortines JR, Parent KN. Microscopic Characterization of the Brazilian Giant Samba Virus. Viruses 2017; 9:v9020030. [PMID: 28216551 PMCID: PMC5332949 DOI: 10.3390/v9020030] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 01/25/2017] [Accepted: 02/02/2017] [Indexed: 12/13/2022] Open
Abstract
Prior to the discovery of the mimivirus in 2003, viruses were thought to be physically small and genetically simple. Mimivirus, with its ~750-nm particle size and its ~1.2-Mbp genome, shattered these notions and changed what it meant to be a virus. Since this discovery, the isolation and characterization of giant viruses has exploded. One of the more recently discovered giant viruses, Samba virus, is a Mimivirus that was isolated from the Rio Negro in the Brazilian Amazon. Initial characterization of Samba has revealed some structural information, although the preparation techniques used are prone to the generation of structural artifacts. To generate more native-like structural information for Samba, we analyzed the virus through cryo-electron microscopy, cryo-electron tomography, scanning electron microscopy, and fluorescence microscopy. These microscopy techniques demonstrated that Samba particles have a capsid diameter of ~527 nm and a fiber length of ~155 nm, making Samba the largest Mimivirus yet characterized. We also compared Samba to a fiberless mimivirus variant. Samba particles, unlike those of mimivirus, do not appear to be rigid, and quasi-icosahedral, although the two viruses share many common features, including a multi-layered capsid and an asymmetric nucleocapsid, which may be common amongst the Mimiviruses.
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Affiliation(s)
- Jason R Schrad
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, 48824 MI, USA.
| | - Eric J Young
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, 48824 MI, USA.
| | - Jônatas S Abrahão
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, 31270-901 Minas Gerais, Brazil.
- Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE) UM63 CNRS 7278 IRD 198 INSERM U1095, Aix-Marseille University, 13385 Marseille Cedex 05, France.
| | - Juliana R Cortines
- Departamento de Virologia, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, 21941-902 Rio de Janeiro, Brazil.
| | - Kristin N Parent
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, 48824 MI, USA.
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56
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Oliveira GP, Andrade ACDSP, Rodrigues RAL, Arantes TS, Boratto PVM, Silva LKDS, Dornas FP, Trindade GDS, Drumond BP, La Scola B, Kroon EG, Abrahão JS. Promoter Motifs in NCLDVs: An Evolutionary Perspective. Viruses 2017; 9:v9010016. [PMID: 28117683 PMCID: PMC5294985 DOI: 10.3390/v9010016] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 12/30/2016] [Accepted: 01/05/2017] [Indexed: 01/18/2023] Open
Abstract
For many years, gene expression in the three cellular domains has been studied in an attempt to discover sequences associated with the regulation of the transcription process. Some specific transcriptional features were described in viruses, although few studies have been devoted to understanding the evolutionary aspects related to the spread of promoter motifs through related viral families. The discovery of giant viruses and the proposition of the new viral order Megavirales that comprise a monophyletic group, named nucleo-cytoplasmic large DNA viruses (NCLDV), raised new questions in the field. Some putative promoter sequences have already been described for some NCLDV members, bringing new insights into the evolutionary history of these complex microorganisms. In this review, we summarize the main aspects of the transcription regulation process in the three domains of life, followed by a systematic description of what is currently known about promoter regions in several NCLDVs. We also discuss how the analysis of the promoter sequences could bring new ideas about the giant viruses’ evolution. Finally, considering a possible common ancestor for the NCLDV group, we discussed possible promoters’ evolutionary scenarios and propose the term “MEGA-box” to designate an ancestor promoter motif (‘TATATAAAATTGA’) that could be evolved gradually by nucleotides’ gain and loss and point mutations.
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Affiliation(s)
- Graziele Pereira Oliveira
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil.
| | - Ana Cláudia Dos Santos Pereira Andrade
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil.
| | - Rodrigo Araújo Lima Rodrigues
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil.
| | - Thalita Souza Arantes
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil.
| | - Paulo Victor Miranda Boratto
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil.
| | - Ludmila Karen Dos Santos Silva
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil.
| | - Fábio Pio Dornas
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil.
| | - Giliane de Souza Trindade
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil.
| | - Betânia Paiva Drumond
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil.
| | - Bernard La Scola
- Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE) UM63 CNRS 7278 IRD 198 INSERM U1095, Aix-Marseille Université., 27 Boulevard Jean Moulin, Faculté de Médecine, 13385 Marseille Cedex 05, France.
| | - Erna Geessien Kroon
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil.
| | - Jônatas Santos Abrahão
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Minas Gerais, Brazil.
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57
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Santos-Pérez I, Oksanen HM, Bamford DH, Goñi FM, Reguera D, Abrescia NGA. Membrane-assisted viral DNA ejection. Biochim Biophys Acta Gen Subj 2016; 1861:664-672. [PMID: 27993658 DOI: 10.1016/j.bbagen.2016.12.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 12/13/2016] [Accepted: 12/15/2016] [Indexed: 11/26/2022]
Abstract
Genome packaging and delivery are fundamental steps in the replication cycle of all viruses. Icosahedral viruses with linear double-stranded DNA (dsDNA) usually package their genome into a preformed, rigid procapsid using the power generated by a virus-encoded packaging ATPase. The pressure and stored energy due to this confinement of DNA at a high density is assumed to drive the initial stages of genome ejection. Membrane-containing icosahedral viruses, such as bacteriophage PRD1, present an additional architectural complexity by enclosing their genome within an internal membrane vesicle. Upon adsorption to a host cell, the PRD1 membrane remodels into a proteo-lipidic tube that provides a conduit for passage of the ejected linear dsDNA through the cell envelope. Based on volume analyses of PRD1 membrane vesicles captured by cryo-electron tomography and modeling of the elastic properties of the vesicle, we propose that the internal membrane makes a crucial and active contribution during infection by maintaining the driving force for DNA ejection and countering the internal turgor pressure of the host. These novel functions extend the role of the PRD1 viral membrane beyond tube formation or the mere physical confinement of the genome. The presence and assistance of an internal membrane might constitute a biological advantage that extends also to other viruses that package their linear dsDNA to high density within an internal vesicle.
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Affiliation(s)
- Isaac Santos-Pérez
- Structural Biology Unit, CIC bioGUNE, CIBERehd, Bizkaia Technology Park, 48160 Derio, Spain
| | - Hanna M Oksanen
- Institute of Biotechnology and Department of Biosciences, Viikki Biocenter, University of Helsinki, P.O. Box 56, Viikinkaari 9B, 00014, Finland
| | - Dennis H Bamford
- Institute of Biotechnology and Department of Biosciences, Viikki Biocenter, University of Helsinki, P.O. Box 56, Viikinkaari 9B, 00014, Finland
| | - Felix M Goñi
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain
| | - David Reguera
- Departament de Física de la Materia Condensada, Facultat de Física, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Nicola G A Abrescia
- Structural Biology Unit, CIC bioGUNE, CIBERehd, Bizkaia Technology Park, 48160 Derio, Spain; IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain.
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58
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The Expanding Family of Virophages. Viruses 2016; 8:v8110317. [PMID: 27886075 PMCID: PMC5127031 DOI: 10.3390/v8110317] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 11/15/2016] [Accepted: 11/15/2016] [Indexed: 12/15/2022] Open
Abstract
Virophages replicate with giant viruses in the same eukaryotic cells. They are a major component of the specific mobilome of mimiviruses. Since their discovery in 2008, five other representatives have been isolated, 18 new genomes have been described, two of which being nearly completely sequenced, and they have been classified in a new viral family, Lavidaviridae. Virophages are small viruses with approximately 35–74 nm large icosahedral capsids and 17–29 kbp large double-stranded DNA genomes with 16–34 genes, among which a very small set is shared with giant viruses. Virophages have been isolated or detected in various locations and in a broad range of habitats worldwide, including the deep ocean and inland. Humans, therefore, could be commonly exposed to virophages, although currently limited evidence exists of their presence in humans based on serology and metagenomics. The distribution of virophages, the consequences of their infection and the interactions with their giant viral hosts within eukaryotic cells deserve further research.
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59
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Efficiency in Complexity: Composition and Dynamic Nature of Mimivirus Replication Factories. J Virol 2016; 90:10039-10047. [PMID: 27581975 DOI: 10.1128/jvi.01319-16] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 08/18/2016] [Indexed: 11/20/2022] Open
Abstract
The recent discovery of multiple giant double-stranded DNA (dsDNA) viruses blurred the consensual distinction between viruses and cells due to their size, as well as to their structural and genetic complexity. A dramatic feature revealed by these viruses as well as by many positive-strand RNA viruses is their ability to rapidly form elaborate intracellular organelles, termed "viral factories," where viral progeny are continuously generated. Here we report the first isolation of viral factories at progressive postinfection time points. The isolated factories were subjected to mass spectrometry-based proteomics, bioinformatics, and imaging analyses. These analyses revealed that numerous viral proteins are present in the factories but not in mature virions, thus implying that multiple and diverse proteins are required to promote the efficiency of viral factories as "production lines" of viral progeny. Moreover, our results highlight the dynamic and highly complex nature of viral factories, provide new and general insights into viral infection, and substantiate the intriguing notion that viral factories may represent the living state of viruses. IMPORTANCE Large dsDNA viruses such as vaccinia virus and the giant mimivirus, as well as many positive-strand RNA viruses, generate elaborate cytoplasmic organelles in which the multiple and diverse transactions required for viral replication and assembly occur. These organelles, which were termed "viral factories," are attracting much interest due to the increasing realization that the rapid and continuous production of viral progeny is a direct outcome of the elaborate structure and composition of the factories, which act as efficient production lines. To get new insights into the nature and function of viral factories, we devised a method that allows, for the first time, the isolation of these organelles. Analyses of the isolated factories generated at different times postinfection by mass spectrometry-based proteomics provide new perceptions of their role and reveal the highly dynamic nature of these organelles.
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60
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Pi F, Zhao Z, Chelikani V, Yoder K, Kvaratskhelia M, Guo P. Development of Potent Antiviral Drugs Inspired by Viral Hexameric DNA-Packaging Motors with Revolving Mechanism. J Virol 2016; 90:8036-46. [PMID: 27356896 PMCID: PMC5008075 DOI: 10.1128/jvi.00508-16] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The intracellular parasitic nature of viruses and the emergence of antiviral drug resistance necessitate the development of new potent antiviral drugs. Recently, a method for developing potent inhibitory drugs by targeting biological machines with high stoichiometry and a sequential-action mechanism was described. Inspired by this finding, we reviewed the development of antiviral drugs targeting viral DNA-packaging motors. Inhibiting multisubunit targets with sequential actions resembles breaking one bulb in a series of Christmas lights, which turns off the entire string. Indeed, studies on viral DNA packaging might lead to the development of new antiviral drugs. Recent elucidation of the mechanism of the viral double-stranded DNA (dsDNA)-packaging motor with sequential one-way revolving motion will promote the development of potent antiviral drugs with high specificity and efficiency. Traditionally, biomotors have been classified into two categories: linear and rotation motors. Recently discovered was a third type of biomotor, including the viral DNA-packaging motor, beside the bacterial DNA translocases, that uses a revolving mechanism without rotation. By analogy, rotation resembles the Earth's rotation on its own axis, while revolving resembles the Earth's revolving around the Sun (see animations at http://rnanano.osu.edu/movie.html). Herein, we review the structures of viral dsDNA-packaging motors, the stoichiometries of motor components, and the motion mechanisms of the motors. All viral dsDNA-packaging motors, including those of dsDNA/dsRNA bacteriophages, adenoviruses, poxviruses, herpesviruses, mimiviruses, megaviruses, pandoraviruses, and pithoviruses, contain a high-stoichiometry machine composed of multiple components that work cooperatively and sequentially. Thus, it is an ideal target for potent drug development based on the power function of the stoichiometries of target complexes that work sequentially.
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Affiliation(s)
- Fengmei Pi
- Division of Pharmaceutics and Pharmaceutical Chemistry, College of Pharmacy, Department of Physiology and Cell Biology, College of Medicine, and the Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio, USA
| | - Zhengyi Zhao
- Division of Pharmaceutics and Pharmaceutical Chemistry, College of Pharmacy, Department of Physiology and Cell Biology, College of Medicine, and the Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio, USA
| | - Venkata Chelikani
- Faculty of Agriculture and Life Sciences, Lincoln University, Lincoln, Canterbury, New Zealand
| | - Kristine Yoder
- Department of Molecular Virology, Immunology, and Medical Genetics, College of Medicine, The Ohio State University, Columbus, Ohio, USA
| | - Mamuka Kvaratskhelia
- Division of Pharmaceutics and Pharmaceutical Chemistry, College of Pharmacy, Department of Physiology and Cell Biology, College of Medicine, and the Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio, USA
| | - Peixuan Guo
- Division of Pharmaceutics and Pharmaceutical Chemistry, College of Pharmacy, Department of Physiology and Cell Biology, College of Medicine, and the Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio, USA
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61
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Abstract
A detailed understanding of chemical and biological function and the mechanisms underlying the molecular activities ultimately requires atomic-resolution structural data. Diffraction-based techniques such as single-crystal X-ray crystallography, electron microscopy, and neutron diffraction are well established and they have paved the road to the stunning successes of modern-day structural biology. The major advances achieved in the last twenty years in all aspects of structural research, including sample preparation, crystallization, the construction of synchrotron and spallation sources, phasing approaches, and high-speed computing and visualization, now provide specialists and nonspecialists alike with a steady flow of molecular images of unprecedented detail. The present unit combines a general overview of diffraction methods with a detailed description of the process of a single-crystal X-ray structure determination experiment, from chemical synthesis or expression to phasing and refinement, analysis, and quality control. For novices it may serve as a stepping-stone to more in-depth treatises of the individual topics. Readers relying on structural information for interpreting functional data may find it a useful consumer guide. © 2016 by John Wiley & Sons, Inc.
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Affiliation(s)
- Martin Egli
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee
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62
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Rodrigues RAL, Abrahão JS, Drumond BP, Kroon EG. Giants among larges: how gigantism impacts giant virus entry into amoebae. Curr Opin Microbiol 2016; 31:88-93. [PMID: 27039270 DOI: 10.1016/j.mib.2016.03.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 03/22/2016] [Accepted: 03/22/2016] [Indexed: 11/29/2022]
Abstract
The proposed order Megavirales comprises the nucleocytoplasmic large DNA viruses (NCLDV), infecting a wide range of hosts. Over time, they co-evolved with different host cells, developing various strategies to penetrate them. Mimiviruses and other giant viruses enter cells through phagocytosis, while Marseillevirus and other large viruses explore endocytosis and macropinocytosis. These differing strategies might reflect the evolution of those viruses. Various scenarios have been proposed for the origin and evolution of these viruses, presenting one of the most enigmatic issues to surround these microorganisms. In this context, we believe that giant viruses evolved independently by massive gene/size gain, exploring the phagocytic pathway of entry into amoebas. In response to gigantism, hosts developed mechanisms to evade these parasites.
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Affiliation(s)
- Rodrigo Araújo Lima Rodrigues
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas (ICB), Universidade Federal de Minas Gerais, Brasil (UFMG), Postal code 486, Belo Horizonte, Minas Gerais, Brazil
| | - Jônatas Santos Abrahão
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas (ICB), Universidade Federal de Minas Gerais, Brasil (UFMG), Postal code 486, Belo Horizonte, Minas Gerais, Brazil
| | - Betânia Paiva Drumond
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas (ICB), Universidade Federal de Minas Gerais, Brasil (UFMG), Postal code 486, Belo Horizonte, Minas Gerais, Brazil
| | - Erna Geessien Kroon
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas (ICB), Universidade Federal de Minas Gerais, Brasil (UFMG), Postal code 486, Belo Horizonte, Minas Gerais, Brazil.
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Infection and Proliferation of Giant Viruses in Amoeba Cells. Uirusu 2016; 66:135-146. [PMID: 29081465 DOI: 10.2222/jsv.66.135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Acanthamoeba polyphaga mimivirus, the first discovered giant virus with genome size and particle size much larger than previously discovered viruses, possesses several genes for translation and CRISPER Cas system-like defense mechanism against virophages, which co-infect amoeba cells with the giant virus and which inhibit giant virus proliferation. Mimiviruses infect amoeba cells by phagocytosis and release their DNA into amoeba cytoplasm through their stargate structure. After infection, giant virion factories (VFs) form in amoeba cytoplasm, followed by DNA replication and particle formation at peripheral regions of VF. Marseilleviruses, the smallest giant viruses, infect amoeba cells by phagocytosis or endocytosis, form larger VF than Mimivirus's VF in amoeba cytoplasm, and replicate their particles. Pandoraviruses found in 2013 have the largest genome size and particle size among all viruses ever found. Pandoraviruses infect amoeba cells by phagocytosis and release their DNA into amoeba cytoplasm through their mouth-like apical pores. The proliferation of Pandoraviruses occurs along with nucleus disruption. New virions form at the periphery of the region formerly occupied by the amoeba cell nucleus.
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64
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Mirza S, Staniewski M, Short C, Long A, Chaban Y, Short S. Isolation and characterization of a virus infecting the freshwater algae Chrysochromulina parva. Virology 2015; 486:105-15. [DOI: 10.1016/j.virol.2015.09.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 08/26/2015] [Accepted: 09/08/2015] [Indexed: 11/26/2022]
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Abergel C, Legendre M, Claverie JM. The rapidly expanding universe of giant viruses: Mimivirus, Pandoravirus, Pithovirus and Mollivirus. FEMS Microbiol Rev 2015; 39:779-96. [PMID: 26391910 DOI: 10.1093/femsre/fuv037] [Citation(s) in RCA: 158] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/15/2015] [Indexed: 12/31/2022] Open
Abstract
More than a century ago, the term 'virus' was introduced to describe infectious agents that are invisible by light microscopy and capable of passing through sterilizing filters. In addition to their extremely small size, most viruses have minimal genomes and gene contents, and rely almost entirely on host cell-encoded functions to multiply. Unexpectedly, four different families of eukaryotic 'giant viruses' have been discovered over the past 10 years with genome sizes, gene contents and particle dimensions overlapping with that of cellular microbes. Their ongoing analyses are challenging accepted ideas about the diversity, evolution and origin of DNA viruses.
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Affiliation(s)
- Chantal Abergel
- Structural and Genomic Information Laboratory, UMR 7256 (IMM FR 3479) Centre National de la Recherche Scientifique & Aix-Marseille University, 13288 Marseille, France
| | - Matthieu Legendre
- Structural and Genomic Information Laboratory, UMR 7256 (IMM FR 3479) Centre National de la Recherche Scientifique & Aix-Marseille University, 13288 Marseille, France
| | - Jean-Michel Claverie
- Structural and Genomic Information Laboratory, UMR 7256 (IMM FR 3479) Centre National de la Recherche Scientifique & Aix-Marseille University, 13288 Marseille, France Assistance Publique des Hôpitaux de Marseille, La Timone, 13005 Marseille, France
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66
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Scheid P. Viruses in close associations with free-living amoebae. Parasitol Res 2015; 114:3959-67. [PMID: 26374538 DOI: 10.1007/s00436-015-4731-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 09/04/2015] [Indexed: 10/23/2022]
Abstract
As both groups of organisms, free-living amoebae (FLA) and viruses, can be found in aquatic environments side by side, it appears obvious that there are multiple interactions with respect to host-endocytobiont relationships. Several relationships between viruses and protozoan hosts are described and it was the discovery of the so called "giant viruses," associated with amoebae, which gave another dimension to these interactions. Mimiviruses, Pandoraviruses and Pithoviruses are examples for interesting viral endocytobionts within FLA. In the Mimivirus viral factories, viral DNA undergoes replication and transcription, and the DNA is prepared to be packed in procapsids. Theses Mimivirus factories can be considered as efficient "production lines" where, at any given moment, all stages of viral generation including membrane biogenesis, capsid assembly and genome encapsidation, are occurring concomitantly. There are some hints that similar replication factories are involved as well during the Pandoravirus development. Some scientists favour the assumption that the giant viruses have received many of their genes from their hosts or from sympatric occurring endocytobionts via lateral gene transfer. This hypothesis would mean that this type of transfer has been an important process in the evolution of genomes in the context of the intracellular parasitic or endocytobiotic lifestyle. In turn, that would migitate against hypothesizing development of a new branch in the tree of life. Based on the described scenarios to explain the presence of genes related to translation, it is also possible that earlier ancestors of today's DNA viruses were involved in the origin of eukaryotes. That possibly could in turn support the idea that cellular organisms could have evolved from viruses with growing autarkic properties. In future we expect the discovery of further (giant) viruses within free-living amoebae and other protozoa through genomic, transcriptomic and proteomic analyses.
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Affiliation(s)
- Patrick Scheid
- Central Institute of the Bundeswehr Medical Service Koblenz, Koblenz, Germany.
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Mimivirus Fibrils Are Important for Viral Attachment to the Microbial World by a Diverse Glycoside Interaction Repertoire. J Virol 2015; 89:11812-9. [PMID: 26378162 DOI: 10.1128/jvi.01976-15] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 09/03/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Acanthamoeba polyphaga mimivirus (APMV) is a giant virus from the Mimiviridae family. It has many unusual features, such as a pseudoicosahedral capsid that presents a starfish shape in one of its vertices, through which the ∼ 1.2-Mb double-stranded DNA is released. It also has a dense glycoprotein fibril layer covering the capsid that has not yet been functionally characterized. Here, we verified that although these structures are not essential for viral replication, they are truly necessary for viral adhesion to amoebae, its natural host. In the absence of fibrils, APMV had a significantly lower level of attachment to the Acanthamoeba castellanii surface. This adhesion is mediated by glycans, specifically, mannose and N-acetylglucosamine (a monomer of chitin and peptidoglycan), both of which are largely distributed in nature as structural components of several organisms. Indeed, APMV was able to attach to different organisms, such as Gram-positive bacteria, fungi, and arthropods, but not to Gram-negative bacteria. This prompted us to predict that (i) arthropods, mainly insects, might act as mimivirus dispersers and (ii) by attaching to other microorganisms, APMV could be ingested by amoebae, leading to the successful production of viral progeny. To date, this mechanism has never been described in the virosphere. IMPORTANCE APMV is a giant virus that is both genetically and structurally complex. Its size is similar to that of small bacteria, and it replicates inside amoebae. The viral capsid is covered by a dense glycoprotein fibril layer, but its function has remained unknown, until now. We found that the fibrils are not essential for mimivirus replication but that they are truly necessary for viral adhesion to the cell surface. This interaction is mediated by glycans, mainly N-acetylglucosamine. We also verified that APMV is able to attach to bacteria, fungi, and arthropods. This indicates that insects might act as mimivirus dispersers and that adhesion to other microorganisms could facilitate viral ingestion by amoebae, a mechanism never before described in the virosphere.
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Zade A, Sengupta M, Kondabagil K. Extensive in silico analysis of Mimivirus coded Rab GTPase homolog suggests a possible role in virion membrane biogenesis. Front Microbiol 2015; 6:929. [PMID: 26441866 PMCID: PMC4569851 DOI: 10.3389/fmicb.2015.00929] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 08/24/2015] [Indexed: 11/29/2022] Open
Abstract
Rab GTPases are the key regulators of intracellular membrane trafficking in eukaryotes. Many viruses and intracellular bacterial pathogens have evolved to hijack the host Rab GTPase functions, mainly through activators and effector proteins, for their benefit. Acanthamoeba polyphaga mimivirus (APMV) is one of the largest viruses and belongs to the monophyletic clade of nucleo-cytoplasmic large DNA viruses (NCLDV). The inner membrane lining is integral to the APMV virion structure. APMV assembly involves extensive host membrane modifications, like vesicle budding and fusion, leading to the formation of a membrane sheet that is incorporated into the virion. Intriguingly, APMV and all group I members of the Mimiviridae family code for a putative Rab GTPase protein. APMV is the first reported virus to code for a Rab GTPase (encoded by R214 gene). Our thorough in silico analysis of the subfamily specific (SF) region of Mimiviridae Rab GTPase sequences suggests that they are related to Rab5, a member of the group II Rab GTPases, of lower eukaryotes. Because of their high divergence from the existing three isoforms, A, B, and C of the Rab5-family, we suggest that Mimiviridae Rabs constitute a new isoform, Rab5D. Phylogenetic analysis indicated probable horizontal acquisition from a lower eukaryotic ancestor followed by selection and divergence. Furthermore, interaction network analysis suggests that vps34 (a Class III PI3K homolog, coded by APMV L615), Atg-8 and dynamin (host proteins) are recruited by APMV Rab GTPase during capsid assembly. Based on these observations, we hypothesize that APMV Rab plays a role in the acquisition of inner membrane during virion assembly.
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Affiliation(s)
- Amrutraj Zade
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay Mumbai, India
| | - Malavi Sengupta
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay Mumbai, India
| | - Kiran Kondabagil
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay Mumbai, India
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69
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Milrot E, Mutsafi Y, Fridmann-Sirkis Y, Shimoni E, Rechav K, Gurnon JR, Van Etten JL, Minsky A. Virus-host interactions: insights from the replication cycle of the large Paramecium bursaria chlorella virus. Cell Microbiol 2015; 18:3-16. [PMID: 26248343 DOI: 10.1111/cmi.12486] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 07/09/2015] [Accepted: 07/15/2015] [Indexed: 12/20/2022]
Abstract
The increasing interest in cytoplasmic factories generated by eukaryotic-infecting viruses stems from the realization that these highly ordered assemblies may contribute fundamental novel insights to the functional significance of order in cellular biology. Here, we report the formation process and structural features of the cytoplasmic factories of the large dsDNA virus Paramecium bursaria chlorella virus 1 (PBCV-1). By combining diverse imaging techniques, including scanning transmission electron microscopy tomography and focused ion beam technologies, we show that the architecture and mode of formation of PBCV-1 factories are significantly different from those generated by their evolutionary relatives Vaccinia and Mimivirus. Specifically, PBCV-1 factories consist of a network of single membrane bilayers acting as capsid templates in the central region, and viral genomes spread throughout the host cytoplasm but excluded from the membrane-containing sites. In sharp contrast, factories generated by Mimivirus have viral genomes in their core, with membrane biogenesis region located at their periphery. Yet, all viral factories appear to share structural features that are essential for their function. In addition, our studies support the notion that PBCV-1 infection, which was recently reported to result in significant pathological outcomes in humans and mice, proceeds through a bacteriophage-like infection pathway.
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Affiliation(s)
- Elad Milrot
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Yael Mutsafi
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Yael Fridmann-Sirkis
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Eyal Shimoni
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Katya Rechav
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - James R Gurnon
- Department of Plant Pathology and Nebraska Center for Virology, University of Nebraska, Lincoln, NE, 68583-0900, USA
| | - James L Van Etten
- Department of Plant Pathology and Nebraska Center for Virology, University of Nebraska, Lincoln, NE, 68583-0900, USA
| | - Abraham Minsky
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, 76100, Israel
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70
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Suarez C, Andres G, Kolovou A, Hoppe S, Salas ML, Walther P, Krijnse Locker J. African swine fever virus assembles a single membrane derived from rupture of the endoplasmic reticulum. Cell Microbiol 2015; 17:1683-98. [PMID: 26096327 DOI: 10.1111/cmi.12468] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 05/05/2015] [Accepted: 05/19/2015] [Indexed: 12/13/2022]
Abstract
Collective evidence argues that two members of the nucleocytoplasmic large DNA viruses (NCLDVs) acquire their membrane from open membrane intermediates, postulated to be derived from membrane rupture. We now study membrane acquisition of the NCLDV African swine fever virus. By electron tomography (ET), the virion assembles a single bilayer, derived from open membrane precursors that collect as ribbons in the cytoplasm. Biochemically, lumenal endoplasmic reticulum (ER) proteins are released into the cytosol, arguing that the open intermediates are ruptured ER membranes. ET shows that viral capsid assembles on the convex side of the open viral membrane to shape it into an icosahedron. The viral capsid is composed of tiny spikes with a diameter of ∼5 nm, connected to the membrane by a 6 nm wide structure displaying thin striations, as observed by several complementary electron microscopy imaging methods. Immature particles display an opening that closes after uptake of the viral genome and core proteins, followed by the formation of the mature virion. Together with our previous data, this study shows a common principle of NCLDVs to build a single internal envelope from open membrane intermediates. Our data now provide biochemical evidence that these open intermediates result from rupture of a cellular membrane, the ER.
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Affiliation(s)
- Cristina Suarez
- Electron Microscopy (EM) Core Facility and Department of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | - German Andres
- Electron Microscopy (EM) Unit, Centro de Biologia Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Madrid, Spain
| | - Androniki Kolovou
- Electron Microscopy (EM) Core Facility and Department of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | - Simone Hoppe
- Electron Microscopy (EM) Core Facility and Department of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | - Maria L Salas
- Virology Department, Centro de Biologia Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Madrid, Spain
| | - Paul Walther
- Electron Microscopy (EM) Core Facility, University of Ulm, Ulm, Germany
| | - Jacomine Krijnse Locker
- Electron Microscopy (EM) Core Facility and Department of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
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Abstract
ABSTRACT In the past decade knowledge about Megaviruses, also denoted as nucleocytoplasmic large DNA viruses (NCLDVs) has been growing quickly. In the current paper, we present a general description of NCLDVs including their genome size, gene functions and homologies to other forms of life and viruses. Evolution of giant viruses from the fourth domain of life (now extinct) and a genomic complexification from smaller DNA viruses are described. Undeniable is the fact that Megaviruses in terms of their size and genomic capacity belong in between cellular and viral worlds breaking several ‘viral dogmas.’ The host range of NCLDVs goes far beyond unicellular organisms and a major challenge in the future is to establish their pathogenicity in human population.
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72
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Klose T, Herbst DA, Zhu H, Max JP, Kenttämaa HI, Rossmann MG. A Mimivirus Enzyme that Participates in Viral Entry. Structure 2015; 23:1058-65. [PMID: 25982526 DOI: 10.1016/j.str.2015.03.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 03/19/2015] [Accepted: 03/26/2015] [Indexed: 10/23/2022]
Abstract
Mimivirus was initially identified as a bacterium because its dense, 125-nm-long fibers stained Gram-positively. These fibers probably play a role during the infection of some host cells. The normal hosts of Mimivirus are unknown, but in the laboratory Mimivirus is usually propagated in amoeba. The structure of R135, a major component of the fibrous outer layer of Mimivirus, has been determined to 2-Å resolution. The protein's structure is similar to that of members of the glucose-methanol-choline oxidoreductase family, which have an N-terminal FAD binding domain and a C-terminal substrate recognition domain. The closest homolog to R135 is an aryl-alcohol oxidase that participates in lignin biodegradation of plant cell walls. Thus R135 might participate in the degradation of their normal hosts, including some lignin-containing algae.
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Affiliation(s)
- Thomas Klose
- Department of Biological Sciences, Purdue University, 240 South Martin Jischke Drive, West Lafayette, IN 47907-2032, USA
| | - Dominik A Herbst
- Department of Biological Sciences, Purdue University, 240 South Martin Jischke Drive, West Lafayette, IN 47907-2032, USA
| | - Hanyu Zhu
- Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Joann P Max
- Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Hilkka I Kenttämaa
- Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Michael G Rossmann
- Department of Biological Sciences, Purdue University, 240 South Martin Jischke Drive, West Lafayette, IN 47907-2032, USA.
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Ekeberg T, Svenda M, Abergel C, Maia FRNC, Seltzer V, Claverie JM, Hantke M, Jönsson O, Nettelblad C, van der Schot G, Liang M, DePonte DP, Barty A, Seibert MM, Iwan B, Andersson I, Loh ND, Martin AV, Chapman H, Bostedt C, Bozek JD, Ferguson KR, Krzywinski J, Epp SW, Rolles D, Rudenko A, Hartmann R, Kimmel N, Hajdu J. Three-dimensional reconstruction of the giant mimivirus particle with an x-ray free-electron laser. PHYSICAL REVIEW LETTERS 2015; 114:098102. [PMID: 25793853 DOI: 10.1103/physrevlett.114.098102] [Citation(s) in RCA: 191] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Indexed: 05/19/2023]
Abstract
We present a proof-of-concept three-dimensional reconstruction of the giant mimivirus particle from experimentally measured diffraction patterns from an x-ray free-electron laser. Three-dimensional imaging requires the assembly of many two-dimensional patterns into an internally consistent Fourier volume. Since each particle is randomly oriented when exposed to the x-ray pulse, relative orientations have to be retrieved from the diffraction data alone. We achieve this with a modified version of the expand, maximize and compress algorithm and validate our result using new methods.
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Affiliation(s)
- Tomas Ekeberg
- Laboratory of Molecular Biophysics, Department of Cell and Molecular Biology, Uppsala University, Husargatan 3 (Box 596), SE-751 24 Uppsala, Sweden
| | - Martin Svenda
- Laboratory of Molecular Biophysics, Department of Cell and Molecular Biology, Uppsala University, Husargatan 3 (Box 596), SE-751 24 Uppsala, Sweden
| | - Chantal Abergel
- Génomique & Structurale - IGS - UMR 7256, CNRS, Aix-Marseille Université, Institut de Microbiologie de la Méditerranée, Parc Scientifique de Luminy, Case 934, 13288 Marseille Cedex 9, France
| | - Filipe R N C Maia
- Laboratory of Molecular Biophysics, Department of Cell and Molecular Biology, Uppsala University, Husargatan 3 (Box 596), SE-751 24 Uppsala, Sweden
- NERSC, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Virginie Seltzer
- Génomique & Structurale - IGS - UMR 7256, CNRS, Aix-Marseille Université, Institut de Microbiologie de la Méditerranée, Parc Scientifique de Luminy, Case 934, 13288 Marseille Cedex 9, France
| | - Jean-Michel Claverie
- Génomique & Structurale - IGS - UMR 7256, CNRS, Aix-Marseille Université, Institut de Microbiologie de la Méditerranée, Parc Scientifique de Luminy, Case 934, 13288 Marseille Cedex 9, France
| | - Max Hantke
- Laboratory of Molecular Biophysics, Department of Cell and Molecular Biology, Uppsala University, Husargatan 3 (Box 596), SE-751 24 Uppsala, Sweden
| | - Olof Jönsson
- Laboratory of Molecular Biophysics, Department of Cell and Molecular Biology, Uppsala University, Husargatan 3 (Box 596), SE-751 24 Uppsala, Sweden
| | - Carl Nettelblad
- Laboratory of Molecular Biophysics, Department of Cell and Molecular Biology, Uppsala University, Husargatan 3 (Box 596), SE-751 24 Uppsala, Sweden
| | - Gijs van der Schot
- Laboratory of Molecular Biophysics, Department of Cell and Molecular Biology, Uppsala University, Husargatan 3 (Box 596), SE-751 24 Uppsala, Sweden
| | - Mengning Liang
- Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Daniel P DePonte
- Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Anton Barty
- Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - M Marvin Seibert
- Laboratory of Molecular Biophysics, Department of Cell and Molecular Biology, Uppsala University, Husargatan 3 (Box 596), SE-751 24 Uppsala, Sweden
- LCLS, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - Bianca Iwan
- Laboratory of Molecular Biophysics, Department of Cell and Molecular Biology, Uppsala University, Husargatan 3 (Box 596), SE-751 24 Uppsala, Sweden
- Attophysics Group, CEA-Saclay, 91191 Gif sur Yvette Cedex, France
| | - Inger Andersson
- Laboratory of Molecular Biophysics, Department of Cell and Molecular Biology, Uppsala University, Husargatan 3 (Box 596), SE-751 24 Uppsala, Sweden
| | - N Duane Loh
- Centre for BioImaging Sciences, National University of Singapore, 14 Science Drive 4 Blk S1 A, Singapore 117546, Singapore
| | - Andrew V Martin
- The University of Melbourne, Parkville, 3010 Victoria, Australia
| | - Henry Chapman
- Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg, Germany
- University of Hamburg, Notkestrasse 85, 22607 Hamburg, Germany
| | - Christoph Bostedt
- LCLS, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - John D Bozek
- LCLS, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - Ken R Ferguson
- LCLS, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - Jacek Krzywinski
- LCLS, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - Sascha W Epp
- Max Planck Advanced Study Group, Center for Free Electron Laser Science, Notkestrasse 85, 22607 Hamburg, Germany
| | - Daniel Rolles
- Max Planck Advanced Study Group, Center for Free Electron Laser Science, Notkestrasse 85, 22607 Hamburg, Germany
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506, USA
| | - Artem Rudenko
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506, USA
| | | | - Nils Kimmel
- Max-Planck-Institut Halbleiterlabor, Otto-Hahn-Ring 6, 81739 München, Germany
- Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, 85741 Garching, Germany
| | - Janos Hajdu
- Laboratory of Molecular Biophysics, Department of Cell and Molecular Biology, Uppsala University, Husargatan 3 (Box 596), SE-751 24 Uppsala, Sweden
- European XFEL, Albert-Einstein-Ring 19, 22761 Hamburg, Germany
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75
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The megavirus chilensis Cu,Zn-superoxide dismutase: the first viral structure of a typical cellular copper chaperone-independent hyperstable dimeric enzyme. J Virol 2014; 89:824-32. [PMID: 25355875 DOI: 10.1128/jvi.02588-14] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Giant viruses able to replicate in Acanthamoeba castellanii penetrate their host through phagocytosis. After capsid opening, a fusion between the internal membranes of the virion and the phagocytic vacuole triggers the transfer in the cytoplasm of the viral DNA together with the DNA repair enzymes and the transcription machinery present in the particles. In addition, the proteome analysis of purified mimivirus virions revealed the presence of many enzymes meant to resist oxidative stress and conserved in the Mimiviridae. Megavirus chilensis encodes a predicted copper, zinc superoxide dismutase (Cu,Zn-SOD), an enzyme known to detoxify reactive oxygen species released in the course of host defense reactions. While it was thought that the metal ions are required for the formation of the active-site lid and dimer stabilization, megavirus chilensis SOD forms a very stable metal-free dimer. We used electron paramagnetic resonance (EPR) analysis and activity measurements to show that the supplementation of the bacterial culture with copper and zinc during the recombinant expression of Mg277 is sufficient to restore a fully active holoenzyme. These results demonstrate that the viral enzyme's activation is independent of a chaperone both for disulfide bridge formation and for copper incorporation and suggest that its assembly may not be as regulated as that of its cellular counterparts. A SOD protein is encoded by a variety of DNA viruses but is absent from mimivirus. As in poxviruses, the enzyme might be dispensable when the virus infects Acanthamoeba cells but may allow megavirus chilensis to infect a broad range of eukaryotic hosts. IMPORTANCE Mimiviridae are giant viruses encoding more than 1,000 proteins. The virion particles are loaded with proteins used by the virus to resist the vacuole's oxidative stress. The megavirus chilensis virion contains a predicted copper, zinc superoxide dismutase (Cu,Zn-SOD). The corresponding gene is present in some megavirus chilensis relatives but is absent from mimivirus. This first crystallographic structure of a viral Cu,Zn-SOD highlights the features that it has in common with and its differences from cellular SODs. It corresponds to a very stable dimer of the apo form of the enzyme. We demonstrate that upon supplementation of the growth medium with Cu and Zn, the recombinant protein is fully active, suggesting that the virus's SOD activation is independent of a copper chaperone for SOD generally used by eukaryotic SODs.
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Infection cycles of large DNA viruses: Emerging themes and underlying questions. Virology 2014; 466-467:3-14. [DOI: 10.1016/j.virol.2014.05.037] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 05/28/2014] [Accepted: 05/30/2014] [Indexed: 11/20/2022]
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77
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From extraordinary endocytobionts to Pandoraviruses. Comment on Scheid et al.: Some secrets are revealed: Parasitic keratitis amoebae as vectors of the scarcely described pandoraviruses to humans. Parasitol Res 2014; 114:1625-7. [DOI: 10.1007/s00436-014-4079-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 08/11/2014] [Indexed: 10/24/2022]
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78
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Some secrets are revealed: parasitic keratitis amoebae as vectors of the scarcely described pandoraviruses to humans. Parasitol Res 2014; 113:3759-64. [DOI: 10.1007/s00436-014-4041-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2014] [Accepted: 07/11/2014] [Indexed: 11/26/2022]
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79
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Risco C, de Castro IF, Sanz-Sánchez L, Narayan K, Grandinetti G, Subramaniam S. Three-Dimensional Imaging of Viral Infections. Annu Rev Virol 2014; 1:453-73. [PMID: 26958730 DOI: 10.1146/annurev-virology-031413-085351] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Three-dimensional (3D) imaging technologies are beginning to have significant impact in the field of virology, as they are helping us understand how viruses take control of cells. In this article we review several methodologies for 3D imaging of cells and show how these technologies are contributing to the study of viral infections and the characterization of specialized structures formed in virus-infected cells. We include 3D reconstruction by transmission electron microscopy (TEM) using serial sections, electron tomography, and focused ion beam scanning electron microscopy (FIB-SEM). We summarize from these methods selected contributions to our understanding of viral entry, replication, morphogenesis, egress and propagation, and changes in the spatial architecture of virus-infected cells. In combination with live-cell imaging, correlative microscopy, and new techniques for molecular mapping in situ, the availability of these methods for 3D imaging is expected to provide deeper insights into understanding the structural and dynamic aspects of viral infection.
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Affiliation(s)
- Cristina Risco
- Cell Structure Laboratory, National Center for Biotechnology (CNB-CSIC), Madrid 28049, Spain;
| | | | - Laura Sanz-Sánchez
- Cell Structure Laboratory, National Center for Biotechnology (CNB-CSIC), Madrid 28049, Spain;
| | - Kedar Narayan
- Laboratory of Cell Biology, National Cancer Institute, Bethesda, Maryland 20892;
| | - Giovanna Grandinetti
- Laboratory of Cell Biology, National Cancer Institute, Bethesda, Maryland 20892;
| | - Sriram Subramaniam
- Laboratory of Cell Biology, National Cancer Institute, Bethesda, Maryland 20892;
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80
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Revisiting the genome packaging in viruses with lessons from the "Giants". Virology 2014; 466-467:15-26. [PMID: 24998349 DOI: 10.1016/j.virol.2014.06.022] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 06/16/2014] [Accepted: 06/17/2014] [Indexed: 11/23/2022]
Abstract
Genome encapsidation is an essential step in the life cycle of viruses. Viruses either use some of the most powerful ATP-dependent motors to compel the genetic material into the preformed capsid or make use of the positively charged proteins to bind and condense the negatively charged genome in an energy-independent manner. While the former is a hallmark of large DNA viruses, the latter is commonly seen in small DNA and RNA viruses. Discoveries of many complex giant viruses such as mimivirus, megavirus, pandoravirus, etc., belonging to the nucleo-cytoplasmic large DNA virus (NCLDV) superfamily have changed the perception of genome packaging in viruses. From what little we have understood so far, it seems that the genome packaging mechanism in NCLDVs has nothing in common with other well-characterized viral packaging systems such as the portal-terminase system or the energy-independent system. Recent findings suggest that in giant viruses, the genome segregation and packaging processes are more intricately coupled than those of other viral systems. Interestingly, giant viral packaging systems also seem to possess features that are analogous to bacterial and archaeal chromosome segregation. Although there is a lot of diversity in terms of host range, type of genome, and genome size among viruses, they all seem to use three major types of independent innovations to accomplish genome encapsidation. Here, we have made an attempt to comprehensively review all the known viral genome packaging systems, including the one that is operative in giant viruses, by proposing a simple and expanded classification system that divides the viral packaging systems into three large groups (types I-III) on the basis of the mechanism employed and the relatedness of the major packaging proteins. Known variants within each group have been further classified into subgroups to reflect their unique adaptations.
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81
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Abstract
Nucleocytoplasmic large dsDNA viruses (NCLDVs) encompass an ever-increasing group of large eukaryotic viruses, infecting a wide variety of organisms. The set of core genes shared by all these viruses includes a major capsid protein with a double jelly-roll fold forming an icosahedral capsid, which surrounds a double layer membrane that contains the viral genome. Furthermore, some of these viruses, such as the members of the Mimiviridae and Phycodnaviridae have a unique vertex that is used during infection to transport DNA into the host.
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Affiliation(s)
- Thomas Klose
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Michael G. Rossmann
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
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82
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Acanthamoeba polyphaga mimivirus and other giant viruses: an open field to outstanding discoveries. Virol J 2014; 11:120. [PMID: 24976356 PMCID: PMC4083134 DOI: 10.1186/1743-422x-11-120] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 06/16/2014] [Indexed: 12/30/2022] Open
Abstract
In 2003, Acanthamoeba polyphaga mimivirus (APMV) was first described and began to impact researchers around the world, due to its structural and genetic complexity. This virus founded the family Mimiviridae. In recent years, several new giant viruses have been isolated from different environments and specimens. Giant virus research is in its initial phase and information that may arise in the coming years may change current conceptions of life, diversity and evolution. Thus, this review aims to condense the studies conducted so far about the features and peculiarities of APMV, from its discovery to its clinical relevance.
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83
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Campos RK, Boratto PV, Assis FL, Aguiar ERGR, Silva LCF, Albarnaz JD, Dornas FP, Trindade GS, Ferreira PP, Marques JT, Robert C, Raoult D, Kroon EG, La Scola B, Abrahão JS. Samba virus: a novel mimivirus from a giant rain forest, the Brazilian Amazon. Virol J 2014; 11:95. [PMID: 24886672 PMCID: PMC4113263 DOI: 10.1186/1743-422x-11-95] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 05/01/2014] [Indexed: 01/09/2023] Open
Abstract
Background The identification of novel giant viruses from the nucleocytoplasmic large DNA viruses group and their virophages has increased in the last decade and has helped to shed light on viral evolution. This study describe the discovery, isolation and characterization of Samba virus (SMBV), a novel giant virus belonging to the Mimivirus genus, which was isolated from the Negro River in the Brazilian Amazon. We also report the isolation of an SMBV-associated virophage named Rio Negro (RNV), which is the first Mimivirus virophage to be isolated in the Americas. Methods/results Based on a phylogenetic analysis, SMBV belongs to group A of the putative Megavirales order, possibly a new virus related to Acanthamoeba polyphaga mimivirus (APMV). SMBV is the largest virus isolated in Brazil, with an average particle diameter about 574 nm. The SMBV genome contains 938 ORFs, of which nine are ORFans. The 1,213.6 kb SMBV genome is one of the largest genome of any group A Mimivirus described to date. Electron microscopy showed RNV particle accumulation near SMBV and APMV factories resulting in the production of defective SMBV and APMV particles and decreasing the infectivity of these two viruses by several logs. Conclusion This discovery expands our knowledge of Mimiviridae evolution and ecology.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | - Bernard La Scola
- Departamento de Microbiologia, Universidade Federal de Minas Gerais, Laboratório de Vírus, Av, Antônio Carlos, 6627 Pampulha, Belo Horizonte, MG Zip Code 31270-901, Brazil.
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84
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Genome segregation and packaging machinery in Acanthamoeba polyphaga mimivirus is reminiscent of bacterial apparatus. J Virol 2014; 88:6069-75. [PMID: 24623441 DOI: 10.1128/jvi.03199-13] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Genome packaging is a critical step in the virion assembly process. The putative ATP-driven genome packaging motor of Acanthamoeba polyphaga mimivirus (APMV) and other nucleocytoplasmic large DNA viruses (NCLDVs) is a distant ortholog of prokaryotic chromosome segregation motors, such as FtsK and HerA, rather than other viral packaging motors, such as large terminase. Intriguingly, APMV also encodes other components, i.e., three putative serine recombinases and a putative type II topoisomerase, all of which are essential for chromosome segregation in prokaryotes. Based on our analyses of these components and taking the limited available literature into account, here we propose for the first time a model for genome segregation and packaging in APMV that can possibly be extended to NCLDV subfamilies, except perhaps Poxviridae and Ascoviridae. This model might represent a unique variation of the prokaryotic system acquired and contrived by the large DNA viruses of eukaryotes. It is also consistent with previous observations that unicellular eukaryotes, such as amoebae, are melting pots for the advent of chimeric organisms with novel mechanisms. IMPORTANCE Extremely large viruses with DNA genomes infect a wide range of eukaryotes, from human beings to amoebae and from crocodiles to algae. These large DNA viruses, unlike their much smaller cousins, have the capability of making most of the protein components required for their multiplication. Once they infect the cell, these viruses set up viral replication centers, known as viral factories, to carry out their multiplication with very little help from the host. Our sequence analyses show that there is remarkable similarity between prokaryotes (bacteria and archaea) and large DNA viruses, such as mimivirus, vaccinia virus, and pandoravirus, in the way that they process their newly synthesized genetic material to make sure that only one copy of the complete genome is generated and is meticulously placed inside the newly synthesized viral particle. These findings have important evolutionary implications about the origin and evolution of large viruses.
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85
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Abstract
This review is a partially personal account of the discovery of virus structure and its implication for virus function. Although I have endeavored to cover all aspects of structural virology and to acknowledge relevant individuals, I know that I have favored taking examples from my own experience in telling this story. I am anxious to apologize to all those who I might have unintentionally offended by omitting their work. The first knowledge of virus structure was a result of Stanley's studies of tobacco mosaic virus (TMV) and the subsequent X-ray fiber diffraction analysis by Bernal and Fankuchen in the 1930s. At about the same time it became apparent that crystals of small RNA plant and animal viruses could diffract X-rays, demonstrating that viruses must have distinct and unique structures. More advances were made in the 1950s with the realization by Watson and Crick that viruses might have icosahedral symmetry. With the improvement of experimental and computational techniques in the 1970s, it became possible to determine the three-dimensional, near-atomic resolution structures of some small icosahedral plant and animal RNA viruses. It was a great surprise that the protecting capsids of the first virus structures to be determined had the same architecture. The capsid proteins of these viruses all had a 'jelly-roll' fold and, furthermore, the organization of the capsid protein in the virus were similar, suggesting a common ancestral virus from which many of today's viruses have evolved. By this time a more detailed structure of TMV had also been established, but both the architecture and capsid protein fold were quite different to that of the icosahedral viruses. The small icosahedral RNA virus structures were also informative of how and where cellular receptors, anti-viral compounds, and neutralizing antibodies bound to these viruses. However, larger lipid membrane enveloped viruses did not form sufficiently ordered crystals to obtain good X-ray diffraction. Starting in the 1990s, these enveloped viruses were studied by combining cryo-electron microscopy of the whole virus with X-ray crystallography of their protein components. These structures gave information on virus assembly, virus neutralization by antibodies, and virus fusion with and entry into the host cell. The same techniques were also employed in the study of complex bacteriophages that were too large to crystallize. Nevertheless, there still remained many pleomorphic, highly pathogenic viruses that lacked the icosahedral symmetry and homogeneity that had made the earlier structural investigations possible. Currently some of these viruses are starting to be studied by combining X-ray crystallography with cryo-electron tomography.
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86
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Kuznetsov YG, Klose T, Rossmann M, McPherson A. Morphogenesis of mimivirus and its viral factories: an atomic force microscopy study of infected cells. J Virol 2013; 87:11200-13. [PMID: 23926353 PMCID: PMC3807284 DOI: 10.1128/jvi.01372-13] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 08/01/2013] [Indexed: 11/20/2022] Open
Abstract
Amoebas infected with mimivirus were disrupted at sequential stages of virus production and were visualized by atomic force microscopy. The development of virus factories proceeded over 3 to 4 h postinfection and resulted from the coalescence of 0.5- to 2-μm vesicles, possibly bearing nucleic acid, derived from either the nuclear membrane or the closely associated rough endoplasmic reticulum. Virus factories actively producing virus capsids on their surfaces were imaged, and this allowed the morphogenesis of the capsids to be delineated. The first feature to appear on a virus factory surface when a new capsid is born is the center of a stargate, which is a pentameric protein oligomer. As the arms of the stargate grow from the pentamer, a rough disk the diameter of a capsid thickens around it. This marks the initial emergence of a protein-coated membrane vesicle. The capsid self-assembles on the vesicle. Hillocks capped by different pentameric proteins spontaneously appear on the emerging vesicle at positions that are ultimately occupied by 5-fold icosahedral vertices. A lattice of coat protein nucleates at each of the 5-fold vertices, but not at the stargate, and then spreads outward from the vertices over the surface, merging seamlessly to complete the icosahedral capsid. Filling with DNA and associated proteins occurs by the transfer of nucleic acid from the interior of the virus factory into the nearly completed capsids. The portal, through which the DNA enters, is sealed by a plug of protein having a diameter of about 40 nm. A layer of integument protein that anchors the surface fibers is acquired by the passage of capsids through a membrane enriched in the protein. The coating of surface fibers is similarly acquired when the integument protein-coated capsids pass through a second membrane that has a forest of surface fibers embedded on one side.
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Affiliation(s)
- Yuri G. Kuznetsov
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California, USA
| | - Thomas Klose
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, USA
| | - Michael Rossmann
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, USA
| | - Alexander McPherson
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California, USA
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87
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Peralta B, Gil-Carton D, Castaño-Díez D, Bertin A, Boulogne C, Oksanen HM, Bamford DH, Abrescia NGA. Mechanism of membranous tunnelling nanotube formation in viral genome delivery. PLoS Biol 2013; 11:e1001667. [PMID: 24086111 PMCID: PMC3782422 DOI: 10.1371/journal.pbio.1001667] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 08/15/2013] [Indexed: 11/19/2022] Open
Abstract
In internal membrane-containing viruses, a lipid vesicle enclosed by the icosahedral capsid protects the genome. It has been postulated that this internal membrane is the genome delivery device of the virus. Viruses built with this architectural principle infect hosts in all three domains of cellular life. Here, using a combination of electron microscopy techniques, we investigate bacteriophage PRD1, the best understood model for such viruses, to unveil the mechanism behind the genome translocation across the cell envelope. To deliver its double-stranded DNA, the icosahedral protein-rich virus membrane transforms into a tubular structure protruding from one of the 12 vertices of the capsid. We suggest that this viral nanotube exits from the same vertex used for DNA packaging, which is biochemically distinct from the other 11. The tube crosses the capsid through an aperture corresponding to the loss of the peripentonal P3 major capsid protein trimers, penton protein P31 and membrane protein P16. The remodeling of the internal viral membrane is nucleated by changes in osmolarity and loss of capsid-membrane interactions as consequence of the de-capping of the vertices. This engages the polymerization of the tail tube, which is structured by membrane-associated proteins. We have observed that the proteo-lipidic tube in vivo can pierce the gram-negative bacterial cell envelope allowing the viral genome to be shuttled to the host cell. The internal diameter of the tube allows one double-stranded DNA chain to be translocated. We conclude that the assembly principles of the viral tunneling nanotube take advantage of proteo-lipid interactions that confer to the tail tube elastic, mechanical and functional properties employed also in other protein-membrane systems.
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Affiliation(s)
- Bibiana Peralta
- Structural Biology Unit, CIC bioGUNE, CIBERehd, Derio, Spain
| | | | - Daniel Castaño-Díez
- Center for Cellular Imaging and Nano-Analitics (C-CINA) Biozentrum, University of Basel, Basel, Switzerland
| | - Aurelie Bertin
- Institut de Biochimie et Biophysique Moléculaire et Cellulaire, Université de Paris–Sud, Orsay, France
| | - Claire Boulogne
- Institut de Biochimie et Biophysique Moléculaire et Cellulaire, Université de Paris–Sud, Orsay, France
| | - Hanna M. Oksanen
- Institute of Biotechnology and Department of Biosciences, Viikki Biocenter, University of Helsinki, Finland
| | - Dennis H. Bamford
- Institute of Biotechnology and Department of Biosciences, Viikki Biocenter, University of Helsinki, Finland
| | - Nicola G. A. Abrescia
- Structural Biology Unit, CIC bioGUNE, CIBERehd, Derio, Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
- * E-mail:
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88
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Philippe N, Legendre M, Doutre G, Couté Y, Poirot O, Lescot M, Arslan D, Seltzer V, Bertaux L, Bruley C, Garin J, Claverie JM, Abergel C. Pandoraviruses: amoeba viruses with genomes up to 2.5 Mb reaching that of parasitic eukaryotes. Science 2013; 341:281-6. [PMID: 23869018 DOI: 10.1126/science.1239181] [Citation(s) in RCA: 393] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Ten years ago, the discovery of Mimivirus, a virus infecting Acanthamoeba, initiated a reappraisal of the upper limits of the viral world, both in terms of particle size (>0.7 micrometers) and genome complexity (>1000 genes), dimensions typical of parasitic bacteria. The diversity of these giant viruses (the Megaviridae) was assessed by sampling a variety of aquatic environments and their associated sediments worldwide. We report the isolation of two giant viruses, one off the coast of central Chile, the other from a freshwater pond near Melbourne (Australia), without morphological or genomic resemblance to any previously defined virus families. Their micrometer-sized ovoid particles contain DNA genomes of at least 2.5 and 1.9 megabases, respectively. These viruses are the first members of the proposed "Pandoravirus" genus, a term reflecting their lack of similarity with previously described microorganisms and the surprises expected from their future study.
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Affiliation(s)
- Nadège Philippe
- Structural and Genomic Information Laboratory, UMR 7256 CNRS Aix-Marseille Université, 163 Avenue de Luminy, Case 934, 13288 Marseille cedex 9, France
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89
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Suárez C, Welsch S, Chlanda P, Hagen W, Hoppe S, Kolovou A, Pagnier I, Raoult D, Krijnse Locker J. Open membranes are the precursors for assembly of large DNA viruses. Cell Microbiol 2013; 15:1883-95. [PMID: 23751082 DOI: 10.1111/cmi.12156] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 05/24/2013] [Accepted: 06/02/2013] [Indexed: 12/16/2022]
Abstract
Nucleo cytoplasmic large DNA viruses (NCLDVs) are a group of double-stranded DNA viruses that replicate their DNA partly or entirely in the cytoplasm in association with viral factories (VFs). They share about 50 genes suggesting that they are derived from a common ancestor. Using transmission electron microscopy (TEM) and electron tomography (ET) we showed that the NCLDV vaccinia virus (VACV) acquires its membrane from open membrane intermediates, derived from the ER. These open membranes contribute to the formation of a single open membrane of the immature virion, shaped into a sphere by the assembly of the viral scaffold protein on its convex side. We now compare VACV with the NCLDV Mimivirus by TEM and ET and show that the latter also acquires its membrane from open membrane intermediates that accumulate at the periphery of the cytoplasmic VF. In analogy to VACV this membrane is shaped by the assembly of a layer on the convexside of its membrane, likely representing the Mimivirus capsid protein. By quantitative ET we show for both viruses that the open membrane intermediates of assembly adopt an 'open-eight' conformation with a characteristic diameter of 90 nm for Mimi- and 50 nm for VACV. We discuss these results with respect to the common ancestry of NCLDVs and propose a hypothesis on the possible origin of this unusual membrane biogenesis.
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Affiliation(s)
- Cristina Suárez
- Electron Microscopy Core Facility, Heidelberg, Germany; Department of Infectious Diseases, Heidelberg University, Im Neuenheimer Feld 267, 69120, Heidelberg, Germany
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90
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Abstract
This chapter discusses the astonishing discovery of the Sputnik virophage, a new virus infecting giant viruses of the genera Mimivirus and Mamavirus. While other virophages have also since been described, this chapter focuses mainly on Sputnik, which is the best described. We detail the general properties of the virophage life cycle, as well as its hosts, genomic characteristics, ecology, and origin. In addition to genetic, phylogenetic, and structural evidence, the existence of virophages has deeply altered our view of the tripartite division of life to include the addition of a fourth domain constituted of the nucleocytoplasmic large DNA viruses, an important point that is discussed.
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Affiliation(s)
- Christelle Desnues
- URMITE, Centre National de la Recherche Scientifique UMR IRD 6236, Faculté de Médecine, Aix-Marseille Université, Marseille, France
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91
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Mutsafi Y, Shimoni E, Shimon A, Minsky A. Membrane assembly during the infection cycle of the giant Mimivirus. PLoS Pathog 2013; 9:e1003367. [PMID: 23737745 PMCID: PMC3667779 DOI: 10.1371/journal.ppat.1003367] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 03/27/2013] [Indexed: 11/18/2022] Open
Abstract
Although extensively studied, the structure, cellular origin and assembly mechanism of internal membranes during viral infection remain unclear. By combining diverse imaging techniques, including the novel Scanning-Transmission Electron Microscopy tomography, we elucidate the structural stages of membrane biogenesis during the assembly of the giant DNA virus Mimivirus. We show that this elaborate multistage process occurs at a well-defined zone localized at the periphery of large viral factories that are generated in the host cytoplasm. Membrane biogenesis is initiated by fusion of multiple vesicles, ~70 nm in diameter, that apparently derive from the host ER network and enable continuous supply of lipid components to the membrane-assembly zone. The resulting multivesicular bodies subsequently rupture to form large open single-layered membrane sheets from which viral membranes are generated. Membrane generation is accompanied by the assembly of icosahedral viral capsids in a process involving the hypothetical major capsid protein L425 that acts as a scaffolding protein. The assembly model proposed here reveals how multiple Mimivirus progeny can be continuously and efficiently generated and underscores the similarity between the infection cycles of Mimivirus and Vaccinia virus. Moreover, the membrane biogenesis process indicated by our findings provides new insights into the pathways that might mediate assembly of internal viral membranes in general.
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Affiliation(s)
- Yael Mutsafi
- Department of Structural Biology, The Weizmann Institute of Science, Rehovot, Israel
| | - Eyal Shimoni
- Department of Chemical Research Support, The Weizmann Institute of Science, Rehovot, Israel
| | - Amir Shimon
- Department of Structural Biology, The Weizmann Institute of Science, Rehovot, Israel
| | - Abraham Minsky
- Department of Structural Biology, The Weizmann Institute of Science, Rehovot, Israel
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92
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Abstract
Viral particles consist essentially of a proteinaceous capsid protecting a genome and involved also in many functions during the virus life cycle. In simple viruses, the capsid consists of a number of copies of the same, or a few different proteins organized into a symmetric oligomer. Structurally complex viruses present a larger variety of components in their capsids than simple viruses. They may contain accessory proteins with specific architectural or functional roles; or incorporate non-proteic elements such as lipids. They present a range of geometrical variability, from slight deviations from the icosahedral symmetry to complete asymmetry or even pleomorphism. Putting together the many different elements in the virion requires an extra effort to achieve correct assembly, and thus complex viruses require sophisticated mechanisms to regulate morphogenesis. This chapter provides a general view of the structure and assembly of complex viruses.
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Affiliation(s)
- Mauricio G. Mateu
- "Severo Ochoa" (CSIC_UAM), And Dept. of Molecular Biology, Centro de Biología Molecular, Cantoblanco, Madrid, 28049 Madrid Spain
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93
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Abstract
Viruses carry out many of their activities inside cells, where they synthesise proteins that are not incorporated into viral particles. Some of these proteins trigger signals to kidnap cell organelles and factors which will form a new macro-structure, the virus factory, that acts as a physical scaffold for viral replication and assembly. We are only beginning to envisage the extraordinary complexity of these interactions, whose characterisation is a clear experimental challenge for which we now have powerful tools. Conventional study of infection kinetics using virology, biochemistry and cell biology methods can be followed by genome-scale screening and global proteomics. These are important new technologies with which we can identify the cell factors used by viruses at different stages in their life cycle. Light microscopy, electron microscopy and electron tomography, together with labelling methods for molecular mapping in situ, show immature viral intermediates, mature virions and recruited cell elements in their natural environment. This chapter describes how these methods are being used to understand the cell biology of viral morphogenesis and suggests what they might achieve in the near future.
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Affiliation(s)
- Mauricio G. Mateu
- "Severo Ochoa" (CSIC_UAM), And Dept. of Molecular Biology, Centro de Biología Molecular, Cantoblanco, Madrid, 28049 Madrid Spain
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94
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Boughalmi M, Saadi H, Pagnier I, Colson P, Fournous G, Raoult D, La Scola B. High-throughput isolation of giant viruses of the Mimiviridae and Marseilleviridae families in the Tunisian environment. Environ Microbiol 2013; 15:2000-7. [PMID: 23298151 DOI: 10.1111/1462-2920.12068] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Revised: 11/29/2012] [Accepted: 11/29/2012] [Indexed: 11/26/2022]
Abstract
Giant viruses of the Megavirales order have been recently isolated from aquatic environments and have long been neglected because they are removed from samples during viral purification for viral metagenomic studies. Due to bacterial overgrowth and susceptibility to high concentrations of antibiotics, isolation by amoeba co-culture has a low efficiency and is highly time-consuming. Thus, few environments have been exhaustively investigated to date, although the ubiquitous distribution of the Acanthamoeba sp. suggests that these viruses could also be ubiquitous. In this work, we have implemented a high-throughput method to detect amoebae lysis on agar plates that allows the testing of hundreds of samples in a few days. Using this procedure, a total of 11 new Marseilleviridae strains and four new Mimiviridae strains, including a virus infected with a virophage, were isolated from 1000 environmental samples from Tunisia. Of these, four corresponded to new genotypic variants. These isolates are the first African environmental isolates identified from these two families, and several samples were obtained from a hypersaline aquatic environment. These results demonstrate that this technique can be used for the evaluation and characterization of large collections of giant viruses to provide insight into understanding their ecology.
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Affiliation(s)
- Mondher Boughalmi
- URMITE, UM63, CNRS 7278, IRD 198, INSERM 1095, Aix Marseille Universite, Marseille, France
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95
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Minsky A, Mutsafi Y. 202 Structural aspects of the infection cycles of giant viruses. J Biomol Struct Dyn 2013. [DOI: 10.1080/07391102.2013.786445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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96
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Lartigue A, Philippe N, Jeudy S, Abergel C. Preliminary crystallographic analysis of the Megavirus superoxide dismutase. Acta Crystallogr Sect F Struct Biol Cryst Commun 2012; 68:1557-9. [PMID: 23192047 PMCID: PMC3509988 DOI: 10.1107/s174430911204657x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Accepted: 11/11/2012] [Indexed: 11/10/2022]
Abstract
Megavirus chilensis, a close relative of the Mimivirus giant virus, is able to replicate in Acanthamoeba castellanii. The first step of viral infection involves the internalization of the virions in host vacuoles. It has been experimentally demonstrated that Mimivirus particles contain many proteins capable of resisting oxidative stress, as encountered in the phagocytic process. These proteins are conserved in Megavirus, which has an additional gene (Mg277) encoding a putative superoxide dismutase. The Mg277 ORF product was overexpressed in Escherichia coli, purified and crystallized. A SAD data set was collected to 2.24 Å resolution at the selenium peak wavelength on the BM30 beamline at the ESRF from a single crystal of selenomethionine-substituted recombinant superoxide dismutase protein.
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Affiliation(s)
- Audrey Lartigue
- Information Génomique et Structurale, IGS UMR7256, CNRS, Aix-Marseille Université, IMM, FR3479, 163 Avenue de Luminy – case 934, 13288 Marseille CEDEX 09, France
| | - Nadège Philippe
- Information Génomique et Structurale, IGS UMR7256, CNRS, Aix-Marseille Université, IMM, FR3479, 163 Avenue de Luminy – case 934, 13288 Marseille CEDEX 09, France
| | - Sandra Jeudy
- Information Génomique et Structurale, IGS UMR7256, CNRS, Aix-Marseille Université, IMM, FR3479, 163 Avenue de Luminy – case 934, 13288 Marseille CEDEX 09, France
| | - Chantal Abergel
- Information Génomique et Structurale, IGS UMR7256, CNRS, Aix-Marseille Université, IMM, FR3479, 163 Avenue de Luminy – case 934, 13288 Marseille CEDEX 09, France
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97
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Abstract
"Sputnik" is a dsDNA virus, referred to as a virophage, that is coassembled with Mimivirus in the host amoeba. We have used cryo-EM to produce an electron density map of the icosahedral Sputnik virus at 3.5-Å resolution, sufficient to verify the identity of most amino acids in the capsid proteins and to establish the identity of the pentameric protein forming the fivefold vertices. It was also shown that the virus lacks an internal membrane. The capsid is organized into a T = 27 lattice in which there are 260 trimeric capsomers and 12 pentameric capsomers. The trimeric capsomers consist of three double "jelly-roll" major capsid proteins creating pseudohexameric capsomer symmetry. The pentameric capsomers consist of five single jelly-roll proteins. The release of the genome by displacing one or more of the pentameric capsomers may be the result of a low-pH environment. These results suggest a mechanism of Sputnik DNA ejection that probably also occurs in other big icosahedral double jelly-roll viruses such as Adenovirus. In this study, the near-atomic resolution structure of a virus has been established where crystallization for X-ray crystallography was not feasible.
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98
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de Castro IF, Volonté L, Risco C. Virus factories: biogenesis and structural design. Cell Microbiol 2012; 15:24-34. [PMID: 22978691 PMCID: PMC7162364 DOI: 10.1111/cmi.12029] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 08/31/2012] [Accepted: 09/04/2012] [Indexed: 12/18/2022]
Abstract
Replication and assembly of many viruses occur in specific intracellular compartments known as ‘virus factories’. Our knowledge of the biogenesis and architecture of these unique structures has increased considerably in the last 10 years, due to technical advances in cellular, molecular and structural biology. We now know that viruses build replication organelles, which recruit cell and viral components in a macrostructure in which viruses assemble and mature. Cell membranes and cytoskeleton participate in the biogenesis of these scaffolds and mitochondria are present in many factories, where they might supply energy and other essential factors. New inter‐organelle contacts have been visualized within virus factories, whose structure is very dynamic, as it changes over time. There is increasing interest in identifying the factors involved in their biogenesis and functional architecture, and new microscopy techniques are helping us to understand how these complex entities are built and work. In this review, we summarize recent findings on the cell biology, biogenesis and structure of virus factories.
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Affiliation(s)
- Isabel Fernández de Castro
- Cell Structure Lab, Centro Nacional de Biotecnología, CNB-CSIC, Darwin 3, Campus de Cantoblanco, 28049 Madrid, Spain
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99
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Nasir A, Kim KM, Caetano-Anolles G. Giant viruses coexisted with the cellular ancestors and represent a distinct supergroup along with superkingdoms Archaea, Bacteria and Eukarya. BMC Evol Biol 2012; 12:156. [PMID: 22920653 PMCID: PMC3570343 DOI: 10.1186/1471-2148-12-156] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 08/22/2012] [Indexed: 11/17/2022] Open
Abstract
Background The discovery of giant viruses with genome and physical size comparable to cellular organisms, remnants of protein translation machinery and virus-specific parasites (virophages) have raised intriguing questions about their origin. Evidence advocates for their inclusion into global phylogenomic studies and their consideration as a distinct and ancient form of life. Results Here we reconstruct phylogenies describing the evolution of proteomes and protein domain structures of cellular organisms and double-stranded DNA viruses with medium-to-very-large proteomes (giant viruses). Trees of proteomes define viruses as a ‘fourth supergroup’ along with superkingdoms Archaea, Bacteria, and Eukarya. Trees of domains indicate they have evolved via massive and primordial reductive evolutionary processes. The distribution of domain structures suggests giant viruses harbor a significant number of protein domains including those with no cellular representation. The genomic and structural diversity embedded in the viral proteomes is comparable to the cellular proteomes of organisms with parasitic lifestyles. Since viral domains are widespread among cellular species, we propose that viruses mediate gene transfer between cells and crucially enhance biodiversity. Conclusions Results call for a change in the way viruses are perceived. They likely represent a distinct form of life that either predated or coexisted with the last universal common ancestor (LUCA) and constitute a very crucial part of our planet’s biosphere.
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Affiliation(s)
- Arshan Nasir
- Evolutionary Bioinformatics Laboratory, Department of Crop Science, University of Illinois, Urbana, IL 61801, USA
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100
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Abstract
In the last twenty years, numerous giant, dsDNA, icosahedral viruses have been discovered and assigned to the nucleocytoplasmic large dsDNA virus (NCLDV) clade. The major capsid proteins of these viruses consist of two consecutive jelly-roll domains, assembled into trimers, with pseudo 6-fold symmetry. The capsomers are assembled into arrays that have either p6 (as in Paramecium bursaria Chlorella virus-1) or p3 symmetry (as in Mimivirus). Most of the NCLDV viruses have a membrane that separates the nucleocapsid from the external capsid.
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Affiliation(s)
- Chuan Xiao
- Department of Chemistry, University of Texas at El Paso, 79968, USA
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