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Yutin N, Tolstoy I, Mutz P, Wolf YI, Krupovic M, Koonin EV. DNA polymerase swapping in Caudoviricetes bacteriophages. Virol J 2024; 21:200. [PMID: 39187833 PMCID: PMC11348598 DOI: 10.1186/s12985-024-02482-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2024] [Accepted: 08/21/2024] [Indexed: 08/28/2024] Open
Abstract
BACKGROUND Viruses with double-stranded (ds) DNA genomes in the realm Duplodnaviria share a conserved structural gene module but show a broad range of variation in their repertoires of DNA replication proteins. Some of the duplodnaviruses encode (nearly) complete replication systems whereas others lack (almost) all genes required for replication, relying on the host replication machinery. DNA polymerases (DNAPs) comprise the centerpiece of the DNA replication apparatus. The replicative DNAPs are classified into 4 unrelated or distantly related families (A-D), with the protein structures and sequences within each family being, generally, highly conserved. More than half of the duplodnaviruses encode a DNAP of family A, B or C. We showed previously that multiple pairs of closely related viruses in the order Crassvirales encode DNAPs of different families. METHODS Groups of phages in which DNAP swapping likely occurred were identified as subtrees of a defined depth in a comprehensive evolutionary tree of tailed bacteriophages that included phages with DNAPs of different families. The DNAP swaps were validated by constrained tree analysis that was performed on phylogenetic tree of large terminase subunits, and the phage genomes encoding swapped DNAPs were aligned using Mauve. The structures of the discovered unusual DNAPs were predicted using AlphaFold2. RESULTS We identified four additional groups of tailed phages in the class Caudoviricetes in which the DNAPs apparently were swapped on multiple occasions, with replacements occurring both between families A and B, or A and C, or between distinct subfamilies within the same family. The DNAP swapping always occurs "in situ", without changes in the organization of the surrounding genes. In several cases, the DNAP gene is the only region of substantial divergence between closely related phage genomes, whereas in others, the swap apparently involved neighboring genes encoding other proteins involved in phage genome replication. In addition, we identified two previously undetected, highly divergent groups of family A DNAPs that are encoded in some phage genomes along with the main DNAP implicated in genome replication. CONCLUSIONS Replacement of the DNAP gene by one encoding a DNAP of a different family occurred on many independent occasions during the evolution of different families of tailed phages, in some cases, resulting in very closely related phages encoding unrelated DNAPs. DNAP swapping was likely driven by selection for avoidance of host antiphage mechanisms targeting the phage DNAP that remain to be identified, and/or by selection against replicon incompatibility.
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Affiliation(s)
- Natalya Yutin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | - Igor Tolstoy
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | - Pascal Mutz
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | - Yuri I Wolf
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | - Mart Krupovic
- Archaeal Virology Unit, Institut Pasteur, Université Paris Cité, Paris, France
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA.
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2
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Forterre P. The Last Universal Common Ancestor of Ribosome-Encoding Organisms: Portrait of LUCA. J Mol Evol 2024:10.1007/s00239-024-10186-9. [PMID: 39158619 DOI: 10.1007/s00239-024-10186-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Accepted: 06/25/2024] [Indexed: 08/20/2024]
Abstract
The existence of LUCA in the distant past is the logical consequence of the binary mechanism of cell division. The biosphere in which LUCA and contemporaries were living was the product of a long cellular evolution from the origin of life to the second age of the RNA world. A parsimonious scenario suggests that the molecular fabric of LUCA was much simpler than those of modern organisms, explaining why the evolutionary tempo was faster at the time of LUCA than it was during the diversification of the three domains. Although LUCA was possibly equipped with a RNA genome and most likely lacked an ATP synthase, it was already able to perform basic metabolic functions and to produce efficient proteins. However, the proteome of LUCA and its inferred metabolism remains to be correctly explored by in-depth phylogenomic analyses and updated datasets. LUCA was probably a mesophile or a moderate thermophile since phylogenetic analyses indicate that it lacked reverse gyrase, an enzyme systematically present in all hyperthermophiles. The debate about the position of Eukarya in the tree of life, either sister group to Archaea or descendants of Archaea, has important implications to draw the portrait of LUCA. In the second alternative, one can a priori exclude the presence of specific eukaryotic features in LUCA. In contrast, if Archaea and Eukarya are sister group, some eukaryotic features, such as the spliceosome, might have been present in LUCA and later lost in Archaea and Bacteria. The nature of the LUCA virome is another matter of debate. I suggest here that DNA viruses only originated during the diversification of the three domains from an RNA-based LUCA to explain the odd distribution pattern of DNA viruses in the tree of life.
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3
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Tembrock LR, Zink FA, Gilligan TM. Viral Prevalence and Genomic Xenology in the Coevolution of HzNV-2 (Nudiviridae) with Host Helicoverpa zea (Lepidoptera: Noctuidae). INSECTS 2023; 14:797. [PMID: 37887809 PMCID: PMC10607169 DOI: 10.3390/insects14100797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 09/16/2023] [Accepted: 09/24/2023] [Indexed: 10/28/2023]
Abstract
Insect viruses have been described from numerous lineages, yet patterns of genetic exchange and viral prevalence, which are essential to understanding host-virus coevolution, are rarely studied. In Helicoverpa zea, the virus HzNV-2 can cause deformity of male and female genitalia, resulting in sterility. Using ddPCR, we found that male H. zea with malformed genitalia (agonadal) contained high levels of HzNV-2 DNA, confirming previous work. HzNV-2 was found to be prevalent throughout the United States, at more than twice the rate of the baculovirus HaSNPV, and that it contained several host-acquired DNA sequences. HzNV-2 possesses four recently endogenized lepidopteran genes and several more distantly related genes, including one gene with a bacteria-like sequence found in both host and virus. Among the recently acquired genes is cytosolic serine hydroxymethyltransferase (cSHMT). In nearly all tested H. zea, cSHMT contained a 200 bp transposable element (TE) that was not found in cSHMT of the sister species H. armigera. No other virus has been found with host cSHMT, and the study of this shared copy, including possible interactions, may yield new insights into the function of this gene with possible applications to insect biological control, and gene editing.
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Affiliation(s)
- Luke R. Tembrock
- Department of Agricultural Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Frida A. Zink
- Department of Agricultural Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Todd M. Gilligan
- USDA-APHIS-PPQ-Science & Technology, Identification Technology Program, Fort Collins, CO 80526, USA
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4
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Simmonds P, Adriaenssens EM, Zerbini FM, Abrescia NGA, Aiewsakun P, Alfenas-Zerbini P, Bao Y, Barylski J, Drosten C, Duffy S, Duprex WP, Dutilh BE, Elena SF, García ML, Junglen S, Katzourakis A, Koonin EV, Krupovic M, Kuhn JH, Lambert AJ, Lefkowitz EJ, Łobocka M, Lood C, Mahony J, Meier-Kolthoff JP, Mushegian AR, Oksanen HM, Poranen MM, Reyes-Muñoz A, Robertson DL, Roux S, Rubino L, Sabanadzovic S, Siddell S, Skern T, Smith DB, Sullivan MB, Suzuki N, Turner D, Van Doorslaer K, Vandamme AM, Varsani A, Vasilakis N. Four principles to establish a universal virus taxonomy. PLoS Biol 2023; 21:e3001922. [PMID: 36780432 PMCID: PMC9925010 DOI: 10.1371/journal.pbio.3001922] [Citation(s) in RCA: 34] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
A universal taxonomy of viruses is essential for a comprehensive view of the virus world and for communicating the complicated evolutionary relationships among viruses. However, there are major differences in the conceptualisation and approaches to virus classification and nomenclature among virologists, clinicians, agronomists, and other interested parties. Here, we provide recommendations to guide the construction of a coherent and comprehensive virus taxonomy, based on expert scientific consensus. Firstly, assignments of viruses should be congruent with the best attainable reconstruction of their evolutionary histories, i.e., taxa should be monophyletic. This fundamental principle for classification of viruses is currently included in the International Committee on Taxonomy of Viruses (ICTV) code only for the rank of species. Secondly, phenotypic and ecological properties of viruses may inform, but not override, evolutionary relatedness in the placement of ranks. Thirdly, alternative classifications that consider phenotypic attributes, such as being vector-borne (e.g., "arboviruses"), infecting a certain type of host (e.g., "mycoviruses," "bacteriophages") or displaying specific pathogenicity (e.g., "human immunodeficiency viruses"), may serve important clinical and regulatory purposes but often create polyphyletic categories that do not reflect evolutionary relationships. Nevertheless, such classifications ought to be maintained if they serve the needs of specific communities or play a practical clinical or regulatory role. However, they should not be considered or called taxonomies. Finally, while an evolution-based framework enables viruses discovered by metagenomics to be incorporated into the ICTV taxonomy, there are essential requirements for quality control of the sequence data used for these assignments. Combined, these four principles will enable future development and expansion of virus taxonomy as the true evolutionary diversity of viruses becomes apparent.
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Affiliation(s)
- Peter Simmonds
- Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | | | - F. Murilo Zerbini
- Departamento de Fitopatologia/BIOAGRO, Universidade Federal de Viçosa, Viçosa, Brazil
| | - Nicola G. A. Abrescia
- Structure and Cell Biology of Viruses Lab, Center for Cooperative Research in Biosciences—BRTA, Derio, Spain
- Basque Foundation for Science, IKERBASQUE, Bilbao, Spain
| | - Pakorn Aiewsakun
- Department of Microbiology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | | | - Yiming Bao
- National Genomics Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jakub Barylski
- Department of Molecular Virology, Adam Mickiewicz University, Poznan, Poland
| | - Christian Drosten
- Institute of Virology, Charité-Universitätsmedizin Berlin, corporate member of Free University Berlin, Humboldt University, Berlin, Germany
- Berlin Institute of Health, Berlin, Germany
| | - Siobain Duffy
- Department of Ecology, Evolution and Natural Resources, School of Environmental and Biological Sciences, Rutgers The State University of New Jersey, New Brunswick, New Jersey, United States of America
| | - W. Paul Duprex
- The Center for Vaccine Research, University of Pittsburgh School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Bas E. Dutilh
- Institute of Biodiversity, Faculty of Biological Sciences, Cluster of Excellence Balance of the Microverse, Friedrich-Schiller-University, Jena, Germany
- Theoretical Biology and Bioinformatics, Science for Life, Utrecht University, Utrecht, the Netherlands
| | - Santiago F. Elena
- Instituto de Biología Integrativa de Sistemas (I2SysBio), CSIC-Universitat de València, Valencia, Spain
- Santa Fe Institute, Santa Fe, New Mexico, United States of America
| | - Maria Laura García
- Instituto de Biotecnología y Biología Molecular, CCT-La Plata, CONICET, UNLP, La Plata, Argentina
| | - Sandra Junglen
- Institute of Virology, Charité-Universitätsmedizin Berlin, corporate member of Free University Berlin, Humboldt University, Berlin, Germany
- Berlin Institute of Health, Berlin, Germany
| | - Aris Katzourakis
- Department of Biology, University of Oxford, Oxford, United Kingdom
| | - Eugene V. Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Mart Krupovic
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Archaeal Virology Unit, Paris, France
| | - Jens H. Kuhn
- Integrated Research Facility at Fort Detrick (IRF-Frederick), National Institute of Allergy and Infectious Diseases, National Institutes of Health, Fort Detrick, Frederick, Maryland, United States of America
| | - Amy J. Lambert
- Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, United States of America
| | - Elliot J. Lefkowitz
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Małgorzata Łobocka
- Institute of Biochemistry and Biophysics of the Polish Academy of Sciences, Warsaw, Poland
| | - Cédric Lood
- Department of Biosystems, KU Leuven, Leuven, Belgium
| | - Jennifer Mahony
- School of Microbiology and APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Jan P. Meier-Kolthoff
- Department of Bioinformatics and Databases, Leibniz Institute DSMZ—German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany
| | - Arcady R. Mushegian
- Division of Molecular and Cellular Biosciences, National Science Foundation, Alexandria, Virginia, United States of America
| | - Hanna M. Oksanen
- Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Minna M. Poranen
- Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Alejandro Reyes-Muñoz
- Max Planck Tandem Group in Computational Biology, Departamento de Ciencias Biológicas, Universidad de los Andes, Bogotá, Colombia
| | - David L. Robertson
- MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
| | - Simon Roux
- Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Luisa Rubino
- Istituto per la Protezione Sostenibile delle Piante, CNR, UOS Bari, Bari, Italy
| | - Sead Sabanadzovic
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Mississippi State, Mississippi, United States of America
| | - Stuart Siddell
- School of Cellular and Molecular Medicine, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
| | - Tim Skern
- Medical University of Vienna, Max Perutz Labs, Vienna Biocenter, Vienna, Austria
| | - Donald B. Smith
- Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Matthew B. Sullivan
- Departments of Microbiology and Civil, Environmental, and Geodetic Engineering, Ohio State University, Columbus, Ohio, United States of America
| | - Nobuhiro Suzuki
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama, Japan
| | - Dann Turner
- School of Applied Sciences, College of Health, Science and Society, University of the West of England, Bristol, United Kingdom
| | - Koenraad Van Doorslaer
- School of Animal and Comparative Biomedical Sciences, Department of Immunobiology, BIO5 Institute, and University of Arizona Cancer Center, Tucson, Arizona, United States of America
| | - Anne-Mieke Vandamme
- KU Leuven, Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Leuven, Belgium
- Center for Global Health and Tropical Medicine, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Lisbon, Portugal
| | - Arvind Varsani
- The Biodesign Center for Fundamental and Applied Microbiomics, School of Life Sciences, Center for Evolution and Medicine, Arizona State University, Tempe, Arizona, United States of America
| | - Nikos Vasilakis
- Department of Pathology, Center of Vector-Borne and Zoonotic Diseases, Institute for Human Infection and Immunity and World Reference Center for Emerging Viruses and Arboviruses, The University of Texas Medical Branch, Galveston, Texas, United States of America
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5
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Abstract
Viruses are the most abundant biological entity on Earth, infect cellular organisms from all domains of life, and are central players in the global biosphere. Over the last century, the discovery and characterization of viruses have progressed steadily alongside much of modern biology. In terms of outright numbers of novel viruses discovered, however, the last few years have been by far the most transformative for the field. Advances in methods for identifying viral sequences in genomic and metagenomic datasets, coupled to the exponential growth of environmental sequencing, have greatly expanded the catalog of known viruses and fueled the tremendous growth of viral sequence databases. Development and implementation of new standards, along with careful study of the newly discovered viruses, have transformed and will continue to transform our understanding of microbial evolution, ecology, and biogeochemical cycles, leading to new biotechnological innovations across many diverse fields, including environmental, agricultural, and biomedical sciences.
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Affiliation(s)
- Lee Call
- Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA; ,
| | - Stephen Nayfach
- Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA; ,
| | - Nikos C Kyrpides
- Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA; ,
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6
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Woo AC, Gaia M, Guglielmini J, Da Cunha V, Forterre P. Phylogeny of the Varidnaviria Morphogenesis Module: Congruence and Incongruence With the Tree of Life and Viral Taxonomy. Front Microbiol 2021; 12:704052. [PMID: 34349745 PMCID: PMC8328091 DOI: 10.3389/fmicb.2021.704052] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Accepted: 06/02/2021] [Indexed: 11/13/2022] Open
Abstract
Double-stranded DNA viruses of the realm Varidnaviria (formerly PRD1-adenovirus lineage) are characterized by homologous major capsid proteins (MCPs) containing one (kingdom: Helvetiavirae) or two β-barrel domains (kingdom: Bamfordvirae) known as the jelly roll folds. Most of them also share homologous packaging ATPases (pATPases). Remarkably, Varidnaviria infect hosts from the three domains of life, suggesting that these viruses could be very ancient and share a common ancestor. Here, we analyzed the evolutionary history of Varidnaviria based on single and concatenated phylogenies of their MCPs and pATPases. We excluded Adenoviridae from our analysis as their MCPs and pATPases are too divergent. Sphaerolipoviridae, the only family in the kingdom Helvetiavirae, exhibit a complex history: their MCPs are very divergent from those of other Varidnaviria, as expected, but their pATPases groups them with Bamfordvirae. In single and concatenated trees, Bamfordvirae infecting archaea were grouped with those infecting bacteria, in contradiction with the cellular tree of life, whereas those infecting eukaryotes were organized into three monophyletic groups: the Nucleocytoviricota phylum, formerly known as the Nucleo-Cytoplasmic Large DNA Viruses (NCLDVs), Lavidaviridae (virophages) and Polintoviruses. Although our analysis mostly supports the recent classification proposed by the International Committee on Taxonomy of Viruses (ICTV), it also raises questions, such as the validity of the Adenoviridae and Helvetiavirae ranking. Based on our phylogeny, we discuss current hypotheses on the origin and evolution of Varidnaviria and suggest new ones to reconcile the viral and cellular trees.
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Affiliation(s)
- Anthony C Woo
- Pôle Analyse de Données UMS 2700 2AD, Muséum National d'Histoire Naturelle, Paris, France.,Département de Microbiologie, Institut Pasteur, Paris, France.,Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Morgan Gaia
- Génomique Métabolique, Génoscope, Institut François Jacob, CEA, CNRS, Univ. Évry, Université Paris-Saclay, Évry, France
| | - Julien Guglielmini
- Hub de Bioinformatique et Biostatistique - Département Biologie Computationnelle, Institut Pasteur, Paris, France
| | - Violette Da Cunha
- Département de Microbiologie, Institut Pasteur, Paris, France.,Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Patrick Forterre
- Département de Microbiologie, Institut Pasteur, Paris, France.,Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
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7
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Abstract
Viruses are the most abundant biological entities on Earth. In addition to their impact on animal and plant health, viruses have important roles in ecosystem dynamics as well as in the evolution of the biosphere. Circular Rep-encoding single-stranded (CRESS) DNA viruses are ubiquitous in nature, many are agriculturally important, and they appear to have multiple origins from prokaryotic plasmids. A subset of CRESS-DNA viruses, the cruciviruses, have homologues of capsid proteins encoded by RNA viruses. The genetic structure of cruciviruses attests to the transfer of capsid genes between disparate groups of viruses. However, the evolutionary history of cruciviruses is still unclear. By collecting and analyzing cruciviral sequence data, we provide a deeper insight into the evolutionary intricacies of cruciviruses. Our results reveal an unexpected diversity of this virus group, with frequent recombination as an important determinant of variability. The discovery of cruciviruses revealed the most explicit example of a common protein homologue between DNA and RNA viruses to date. Cruciviruses are a novel group of circular Rep-encoding single-stranded DNA (ssDNA) (CRESS-DNA) viruses that encode capsid proteins that are most closely related to those encoded by RNA viruses in the family Tombusviridae. The apparent chimeric nature of the two core proteins encoded by crucivirus genomes suggests horizontal gene transfer of capsid genes between DNA and RNA viruses. Here, we identified and characterized 451 new crucivirus genomes and 10 capsid-encoding circular genetic elements through de novo assembly and mining of metagenomic data. These genomes are highly diverse, as demonstrated by sequence comparisons and phylogenetic analysis of subsets of the protein sequences they encode. Most of the variation is reflected in the replication-associated protein (Rep) sequences, and much of the sequence diversity appears to be due to recombination. Our results suggest that recombination tends to occur more frequently among groups of cruciviruses with relatively similar capsid proteins and that the exchange of Rep protein domains between cruciviruses is rarer than intergenic recombination. Additionally, we suggest members of the stramenopiles/alveolates/Rhizaria supergroup as possible crucivirus hosts. Altogether, we provide a comprehensive and descriptive characterization of cruciviruses.
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8
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Abstract
The last universal cellular ancestor (LUCA) is the most recent population of organisms from which all cellular life on Earth descends. The reconstruction of the genome and phenotype of the LUCA is a major challenge in evolutionary biology. Given that all life forms are associated with viruses and/or other mobile genetic elements, there is no doubt that the LUCA was a host to viruses. Here, by projecting back in time using the extant distribution of viruses across the two primary domains of life, bacteria and archaea, and tracing the evolutionary histories of some key virus genes, we attempt a reconstruction of the LUCA virome. Even a conservative version of this reconstruction suggests a remarkably complex virome that already included the main groups of extant viruses of bacteria and archaea. We further present evidence of extensive virus evolution antedating the LUCA. The presence of a highly complex virome implies the substantial genomic and pan-genomic complexity of the LUCA itself.
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9
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Targeting of the cGAS-STING system by DNA viruses. Biochem Pharmacol 2020; 174:113831. [DOI: 10.1016/j.bcp.2020.113831] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 01/24/2020] [Indexed: 12/15/2022]
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10
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Abstract
Viruses are ubiquitous parasites of cellular life and the most abundant biological entities on Earth. It is widely accepted that viruses are polyphyletic, but a consensus scenario for their ultimate origin is still lacking. Traditionally, three scenarios for the origin of viruses have been considered: descent from primordial, precellular genetic elements, reductive evolution from cellular ancestors and escape of genes from cellular hosts, achieving partial replicative autonomy and becoming parasitic genetic elements. These classical scenarios give different timelines for the origin(s) of viruses and do not explain the provenance of the two key functional modules that are responsible, respectively, for viral genome replication and virion morphogenesis. Here, we outline a 'chimeric' scenario under which different types of primordial, selfish replicons gave rise to viruses by recruiting host proteins for virion formation. We also propose that new groups of viruses have repeatedly emerged at all stages of the evolution of life, often through the displacement of ancestral structural and genome replication genes.
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11
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Coulibaly F. Polyhedra, spindles, phage nucleus and pyramids: Structural biology of viral superstructures. Adv Virus Res 2019; 105:275-335. [PMID: 31522707 DOI: 10.1016/bs.aivir.2019.08.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Viral infection causes comprehensive rearrangements of the cell that reflect as much host defense mechanisms as virus-induced structures assembled to facilitate infection. Regardless of their pro- or antiviral role, large intracellular structures are readily detectable by microscopy and often provide a signature characteristic of a specific viral infection. The structural features and localization of these assemblies have thus been commonly used for the diagnostic and classification of viruses since the early days of virology. More recently, characterization of viral superstructures using molecular and structural approaches have revealed very diverse organizations and roles, ranging from dynamic viral factories behaving like liquid organelles to ultra-stable crystals embedding and protecting virions. This chapter reviews the structures, functions and biotechnological applications of virus-induced superstructures with a focus on assemblies that have a regular organization, for which detailed structural descriptions are available. Examples span viruses infecting all domains of life including the assembly of virions into crystalline arrays in eukaryotic and bacterial viruses, nucleus-like compartments involved in the replication of large bacteriophages, and pyramid-like structures mediating the egress of archaeal viruses. Among these superstructures, high-resolution structures are available for crystalline objects produced by insect viruses: viral polyhedra which function as the infectious form of occluded viruses, and spindles which are potent virulence factors of entomopoxviruses. In turn, some of these highly symmetrical objects have been used to develop and validate advanced structural approaches, pushing the boundary of structural biology.
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Affiliation(s)
- Fasséli Coulibaly
- Infection & Immunity Program, Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia.
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12
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Liu Y, Brandt D, Ishino S, Ishino Y, Koonin EV, Kalinowski J, Krupovic M, Prangishvili D. New archaeal viruses discovered by metagenomic analysis of viral communities in enrichment cultures. Environ Microbiol 2019; 21:2002-2014. [PMID: 30451355 PMCID: PMC11128462 DOI: 10.1111/1462-2920.14479] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 11/07/2018] [Accepted: 11/10/2018] [Indexed: 12/20/2022]
Abstract
Viruses infecting hyperthermophilic archaea of the phylum Crenarchaeota display enormous morphological and genetic diversity, and are classified into 12 families. Eight of these families include only one or two species, indicating sparse sampling of the crenarchaeal virus diversity. In an attempt to expand the crenarchaeal virome, we explored virus diversity in the acidic, hot spring Umi Jigoku in Beppu, Japan. Environmental samples were used to establish enrichment cultures under conditions favouring virus replication. The host diversity in the enrichment cultures was restricted to members of the order Sulfolobales. Metagenomic sequencing of the viral communities yielded seven complete or near-complete double-stranded DNA virus genomes. Six of these genomes could be attributed to polyhedral and filamentous viruses that were observed by electron microscopy in the enrichment cultures. Two icosahedral viruses represented species in the family Portogloboviridae. Among the filamentous viruses, two were identified as new species in the families Rudiviridae and Lipothrixviridae, whereas two other formed a group seemingly distinct from the known virus genera. No particle morphotype could be unequivocally assigned to the seventh viral genome, which apparently represents a new virus type. Our results suggest that filamentous viruses are globally distributed and are prevalent virus types in extreme geothermal environments.
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Affiliation(s)
- Ying Liu
- Department of Microbiology, BMGE, Institut Pasteur, Paris 75015, France
| | - David Brandt
- Center for Biotechnology, Universität Bielefeld, Bielefeld 33615, Germany
| | - Sonoko Ishino
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Fukuoka 819-0395, Japan
| | - Yoshizumi Ishino
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Fukuoka 819-0395, Japan
| | - Eugene V. Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jörn Kalinowski
- Center for Biotechnology, Universität Bielefeld, Bielefeld 33615, Germany
| | - Mart Krupovic
- Department of Microbiology, BMGE, Institut Pasteur, Paris 75015, France
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13
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Gill S, Catchpole R, Forterre P. Extracellular membrane vesicles in the three domains of life and beyond. FEMS Microbiol Rev 2019; 43:273-303. [PMID: 30476045 PMCID: PMC6524685 DOI: 10.1093/femsre/fuy042] [Citation(s) in RCA: 264] [Impact Index Per Article: 52.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 11/20/2018] [Indexed: 02/06/2023] Open
Abstract
Cells from all three domains of life, Archaea, Bacteria and Eukarya, produce extracellular vesicles (EVs) which are sometimes associated with filamentous structures known as nanopods or nanotubes. The mechanisms of EV biogenesis in the three domains remain poorly understood, although studies in Bacteria and Eukarya indicate that the regulation of lipid composition plays a major role in initiating membrane curvature. EVs are increasingly recognized as important mediators of intercellular communication via transfer of a wide variety of molecular cargoes. They have been implicated in many aspects of cell physiology such as stress response, intercellular competition, lateral gene transfer (via RNA or DNA), pathogenicity and detoxification. Their role in various human pathologies and aging has aroused much interest in recent years. EVs can be used as decoys against viral attack but virus-infected cells also produce EVs that boost viral infection. Here, we review current knowledge on EVs in the three domains of life and their interactions with the viral world.
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Affiliation(s)
- Sukhvinder Gill
- Institute for Integrative Biology of the Cell (I2BC), Biologie Cellulaire des Archées (BCA), CEA, CNRS, Université Paris-Sud, 91405 Orsay cedex, France
| | - Ryan Catchpole
- Institut Pasteur, Unité de Biologie Moléculaire du Gène chez les Extrêmophiles, Département de Microbiologie, F75015 Paris, France
| | - Patrick Forterre
- Institute for Integrative Biology of the Cell (I2BC), Biologie Cellulaire des Archées (BCA), CEA, CNRS, Université Paris-Sud, 91405 Orsay cedex, France
- Institut Pasteur, Unité de Biologie Moléculaire du Gène chez les Extrêmophiles, Département de Microbiologie, F75015 Paris, France
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14
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Mizuno CM, Prajapati B, Lucas‐Staat S, Sime‐Ngando T, Forterre P, Bamford DH, Prangishvili D, Krupovic M, Oksanen HM. Novel haloarchaeal viruses from Lake Retba infecting
Haloferax
and
Halorubrum
species. Environ Microbiol 2019; 21:2129-2147. [DOI: 10.1111/1462-2920.14604] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 03/15/2019] [Accepted: 03/21/2019] [Indexed: 11/30/2022]
Affiliation(s)
- Carolina M. Mizuno
- Unité Biologie Moléculaire du Gène chez les ExtrêmophilesInstitut Pasteur, 25 rue du Docteur Roux 75015, Paris France
| | - Bina Prajapati
- Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental SciencesUniversity of Helsinki Finland
| | - Soizick Lucas‐Staat
- Unité Biologie Moléculaire du Gène chez les ExtrêmophilesInstitut Pasteur, 25 rue du Docteur Roux 75015, Paris France
| | - Telesphore Sime‐Ngando
- CNRS UMR 6023, Université Clermont‐AuvergneLaboratoire "Microorganismes: Génome et Environnement" (LMGE) F‐63000, Clermont‐Ferrand France
| | - Patrick Forterre
- Unité Biologie Moléculaire du Gène chez les ExtrêmophilesInstitut Pasteur, 25 rue du Docteur Roux 75015, Paris France
| | - Dennis H. Bamford
- Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental SciencesUniversity of Helsinki Finland
| | - David Prangishvili
- Unité Biologie Moléculaire du Gène chez les ExtrêmophilesInstitut Pasteur, 25 rue du Docteur Roux 75015, Paris France
| | - Mart Krupovic
- Unité Biologie Moléculaire du Gène chez les ExtrêmophilesInstitut Pasteur, 25 rue du Docteur Roux 75015, Paris France
| | - Hanna M. Oksanen
- Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental SciencesUniversity of Helsinki Finland
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15
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Alam CM, Iqbal A, Sharma A, Schulman AH, Ali S. Microsatellite Diversity, Complexity, and Host Range of Mycobacteriophage Genomes of the Siphoviridae Family. Front Genet 2019; 10:207. [PMID: 30923537 PMCID: PMC6426759 DOI: 10.3389/fgene.2019.00207] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 02/26/2019] [Indexed: 01/21/2023] Open
Abstract
The incidence, distribution, and variation of simple sequence repeats (SSRs) in viruses is instrumental in understanding the functional and evolutionary aspects of repeat sequences. Full-length genome sequences retrieved from NCBI were used for extraction and analysis of repeat sequences using IMEx software. We have also developed two MATLAB-based tools for extraction of gene locations from GenBank in tabular format and simulation of this data with SSR incidence data. Present study encompassing 147 Mycobacteriophage genomes revealed 25,284 SSRs and 1,127 compound SSRs (cSSRs) through IMEx. Mono- to hexa-nucleotide motifs were present. The SSR count per genome ranged from 78 (M100) to 342 (M58) while cSSRs incidence ranged from 1 (M138) to 17 (M28, M73). Though cSSRs were present in all the genomes, their frequency and SSR to cSSR conversion percentage varied from 1.08 (M138 with 93 SSRs) to 8.33 (M116 with 96 SSRs). In terms of localization, the SSRs were predominantly localized to coding regions (∼78%). Interestingly, genomes of around 50 kb contained a similar number of SSRs/cSSRs to that in a 110 kb genome, suggesting functional relevance for SSRs which was substantiated by variation in motif constitution between species with different host range. The three species with broad host range (M97, M100, M116) have around 90% of their mono-nucleotide repeat motifs composed of G or C and only M16 has both A and T mononucleotide motifs. Around 20% of the di-nucleotide repeat motifs in the genomes exhibiting a broad host range were CT/TC, which were either absent or represented to a much lesser extent in the other genomes.
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Affiliation(s)
- Chaudhary Mashhood Alam
- Luke/BI Plant Genome Dynamics Lab, Institute of Biotechnology and Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland.,Ingenious e-Brain Solutions, Gurugram, India
| | - Asif Iqbal
- PIRO Technologies Private Limited, New Delhi, India
| | - Anjana Sharma
- Department of Biomedical Sciences, SRCASW, University of Delhi, New Delhi, India
| | - Alan H Schulman
- Luke/BI Plant Genome Dynamics Lab, Institute of Biotechnology and Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland.,Natural Resources Institute Finland (Luke), Helsinki, Finland
| | - Safdar Ali
- Department of Biomedical Sciences, SRCASW, University of Delhi, New Delhi, India.,Department of Biological Sciences, Aliah University, Kolkata, India
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16
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Villarreal LP, Witzany G. That is life: communicating RNA networks from viruses and cells in continuous interaction. Ann N Y Acad Sci 2019; 1447:5-20. [PMID: 30865312 DOI: 10.1111/nyas.14040] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 01/13/2019] [Accepted: 01/31/2019] [Indexed: 02/06/2023]
Abstract
All the conserved detailed results of evolution stored in DNA must be read, transcribed, and translated via an RNA-mediated process. This is required for the development and growth of each individual cell. Thus, all known living organisms fundamentally depend on these RNA-mediated processes. In most cases, they are interconnected with other RNAs and their associated protein complexes and function in a strictly coordinated hierarchy of temporal and spatial steps (i.e., an RNA network). Clearly, all cellular life as we know it could not function without these key agents of DNA replication, namely rRNA, tRNA, and mRNA. Thus, any definition of life that lacks RNA functions and their networks misses an essential requirement for RNA agents that inherently regulate and coordinate (communicate to) cells, tissues, organs, and organisms. The precellular evolution of RNAs occurred at the core of the emergence of cellular life and the question remained of how both precellular and cellular levels are interconnected historically and functionally. RNA networks and RNA communication can interconnect these levels. With the reemergence of virology in evolution, it became clear that communicating viruses and subviral infectious genetic parasites are bridging these two levels by invading, integrating, coadapting, exapting, and recombining constituent parts in host genomes for cellular requirements in gene regulation and coordination aims. Therefore, a 21st century understanding of life is of an inherently social process based on communicating RNA networks, in which viruses and cells continuously interact.
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Affiliation(s)
- Luis P Villarreal
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California
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17
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Koonin EV, Krupovic M. The depths of virus exaptation. Curr Opin Virol 2018; 31:1-8. [PMID: 30071360 DOI: 10.1016/j.coviro.2018.07.011] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 07/13/2018] [Accepted: 07/19/2018] [Indexed: 02/07/2023]
Abstract
Viruses are ubiquitous parasites of cellular life forms and the most abundant biological entities on earth. The relationships between viruses and their hosts involve the continuous arms race but are by no account limited to it. Growing evidence shows that, in the course of evolution, viruses and their components are repeatedly recruited (exapted) for host functions. The functions of exapted viruses typically involve either defense from other viruses or cellular competitors or transfer of nucleic acids between cells, or storage functions. Virus exaptation can reach different depths, from recruitment of a fully functional virus to exploitation of defective, partially degraded viruses, to utilization of individual virus proteins.
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Affiliation(s)
- Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, United States.
| | - Mart Krupovic
- Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Department of Microbiology, Institut Pasteur, 25 rue du Docteur Roux, Paris 75015, France.
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18
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Abstract
Due to their dependence on cellular organisms for metabolism and replication, viruses are typically named and assigned to species according to their genome structure and the original host that they infect. But because viruses often infect multiple hosts and the numbers of distinct lineages within a host can be vast, their delineation into species is often dictated by arbitrary sequence thresholds, which are highly inconsistent across lineages. Here we apply an approach to determine the boundaries of viral species based on the detection of gene flow within populations, thereby defining viral species according to the biological species concept (BSC). Despite the potential for gene transfer between highly divergent genomes, viruses, like the cellular organisms they infect, assort into reproductively isolated groups and can be organized into biological species. This approach revealed that BSC-defined viral species are often congruent with the taxonomic partitioning based on shared gene contents and host tropism, and that bacteriophages can similarly be classified in biological species. These results open the possibility to use a single, universal definition of species that is applicable across cellular and acellular lifeforms.
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19
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Forterre P. Viruses in the 21st Century: From the Curiosity-Driven Discovery of Giant Viruses to New Concepts and Definition of Life. Clin Infect Dis 2018; 65:S74-S79. [PMID: 28859344 DOI: 10.1093/cid/cix349] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The curiosity-driven discovery of giant DNA viruses infecting amoebas has triggered an intense debate about the origin, nature, and definition of viruses. This discovery was delayed by the current paradigm confusing viruses with small virions. Several new definitions and concepts have been proposed either to reconcile the unique features of giant viruses with previous paradigms or to propose a completely new vision of the living world. I briefly review here how several other lines of research in virology converged during the last 2 decades with the discovery of giant viruses to change our traditional perception of the viral world. This story emphasizes the power of multidisciplinary curiosity-driven research, from the hospital to the field and the laboratory. Notably, some philosophers have now also joined biologists in their quest to make sense of the abundance and diversity of viruses and related capsidless mobile elements in the biosphere.
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Affiliation(s)
- Patrick Forterre
- Institut Pasteur, Département de Microbiologie, Paris; and Institut Intégré de Biologie Cellulaire, Département de Microbiologie, Centre National de la Recherche Scientifique, Université Paris-Saclay, France
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20
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Yutin N, Bäckström D, Ettema TJG, Krupovic M, Koonin EV. Vast diversity of prokaryotic virus genomes encoding double jelly-roll major capsid proteins uncovered by genomic and metagenomic sequence analysis. Virol J 2018; 15:67. [PMID: 29636073 PMCID: PMC5894146 DOI: 10.1186/s12985-018-0974-y] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 03/28/2018] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Analysis of metagenomic sequences has become the principal approach for the study of the diversity of viruses. Many recent, extensive metagenomic studies on several classes of viruses have dramatically expanded the visible part of the virosphere, showing that previously undetected viruses, or those that have been considered rare, actually are important components of the global virome. RESULTS We investigated the provenance of viruses related to tail-less bacteriophages of the family Tectiviridae by searching genomic and metagenomics sequence databases for distant homologs of the tectivirus-like Double Jelly-Roll major capsid proteins (DJR MCP). These searches resulted in the identification of numerous genomes of virus-like elements that are similar in size to tectiviruses (10-15 kilobases) and have diverse gene compositions. By comparison of the gene repertoires, the DJR MCP-encoding genomes were classified into 6 distinct groups that can be predicted to differ in reproduction strategies and host ranges. Only the DJR MCP gene that is present by design is shared by all these genomes, and most also encode a predicted DNA-packaging ATPase; the rest of the genes are present only in subgroups of this unexpectedly diverse collection of DJR MCP-encoding genomes. Only a minority encode a DNA polymerase which is a hallmark of the family Tectiviridae and the putative family "Autolykiviridae". Notably, one of the identified putative DJR MCP viruses encodes a homolog of Cas1 endonuclease, the integrase involved in CRISPR-Cas adaptation and integration of transposon-like elements called casposons. This is the first detected occurrence of Cas1 in a virus. Many of the identified elements are individual contigs flanked by inverted or direct repeats and appear to represent complete, extrachromosomal viral genomes, whereas others are flanked by bacterial genes and thus can be considered as proviruses. These contigs come from metagenomes of widely different environments, some dominated by archaea and others by bacteria, suggesting that collectively, the DJR MCP-encoding elements have a broad host range among prokaryotes. CONCLUSIONS The findings reported here greatly expand the known host range of (putative) viruses of bacteria and archaea that encode a DJR MCP. They also demonstrate the extreme diversity of genome architectures in these viruses that encode no universal proteins other than the capsid protein that was used as the marker for their identification. From a supposedly minor group of bacterial and archaeal viruses, these viruses are emerging as a substantial component of the prokaryotic virome.
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Affiliation(s)
- Natalya Yutin
- National Center for Biotechnology Information, National Library of Medicine. National Institutes of Health, Bethesda, MD, 20894, USA
| | - Disa Bäckström
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Box 596, -75123, Uppsala, SE, Sweden
| | - Thijs J G Ettema
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Box 596, -75123, Uppsala, SE, Sweden
| | - Mart Krupovic
- Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Department of Microbiology, Institut Pasteur, Paris, France
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine. National Institutes of Health, Bethesda, MD, 20894, USA.
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21
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Extending the hosts of Tectiviridae into four additional genera of Gram-positive bacteria and more diverse Bacillus species. Virology 2018; 518:136-142. [PMID: 29481984 DOI: 10.1016/j.virol.2018.02.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 02/14/2018] [Accepted: 02/16/2018] [Indexed: 11/23/2022]
Abstract
Tectiviridae are composed of tailless bacteriophages with an icosahedral capsid and an inner membrane enclosing a double-stranded 15 kb linear DNA genome. Five of the seven previously studied Tectivirus isolates infect bacteria from Bacillus cereus sensu lato group (Betatectivirus), one distantly related member (PRD1) infect Enterobactericeae (Alpatectivirus) and one recently discovered virus infect Gluconobacter cerinus (Gammatectivirus). Here we expand the host spectrum of Betatectivirus elements to four additional genera (Streptococcus, Exiguobacterium, Clostridium and Brevibacillus) and to more distantly related Bacillus species (B. pumilus and B. flexus) by studying the genomes of fourteen novel tectiviral elements. Overall, the genomes show significant conservation in gene synteny and in modules responsible for genome replication and formation of the virion core (including DNA packaging). Notable variation exists in regions encoding host attachment and lysis along with the surrounding area of a site in which mutations are known to alter phage life cycle.
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22
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Berliner AJ, Mochizuki T, Stedman KM. Astrovirology: Viruses at Large in the Universe. ASTROBIOLOGY 2018; 18:207-223. [PMID: 29319335 DOI: 10.1089/ast.2017.1649] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Viruses are the most abundant biological entities on modern Earth. They are highly diverse both in structure and genomic sequence, play critical roles in evolution, strongly influence terran biogeochemistry, and are believed to have played important roles in the origin and evolution of life. However, there is yet very little focus on viruses in astrobiology. Viruses arguably have coexisted with cellular life-forms since the earliest stages of life, may have been directly involved therein, and have profoundly influenced cellular evolution. Viruses are the only entities on modern Earth to use either RNA or DNA in both single- and double-stranded forms for their genetic material and thus may provide a model for the putative RNA-protein world. With this review, we hope to inspire integration of virus research into astrobiology and also point out pressing unanswered questions in astrovirology, particularly regarding the detection of virus biosignatures and whether viruses could be spread extraterrestrially. We present basic virology principles, an inclusive definition of viruses, review current virology research pertinent to astrobiology, and propose ideas for future astrovirology research foci. Key Words: Astrobiology-Virology-Biosignatures-Origin of life-Roadmap. Astrobiology 18, 207-223.
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Affiliation(s)
| | | | - Kenneth M Stedman
- 3 Center for Life in Extreme Environments and Biology Department, Portland State University , Oregon, USA
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23
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Krupovic M, Cvirkaite-Krupovic V, Iranzo J, Prangishvili D, Koonin EV. Viruses of archaea: Structural, functional, environmental and evolutionary genomics. Virus Res 2017; 244:181-193. [PMID: 29175107 DOI: 10.1016/j.virusres.2017.11.025] [Citation(s) in RCA: 139] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 11/20/2017] [Accepted: 11/20/2017] [Indexed: 11/18/2022]
Abstract
Viruses of archaea represent one of the most enigmatic parts of the virosphere. Most of the characterized archaeal viruses infect extremophilic hosts and display remarkable diversity of virion morphotypes, many of which have never been observed among viruses of bacteria or eukaryotes. The uniqueness of the virion morphologies is matched by the distinctiveness of the genomes of these viruses, with ∼75% of genes encoding unique proteins, refractory to functional annotation based on sequence analyses. In this review, we summarize the state-of-the-art knowledge on various aspects of archaeal virus genomics. First, we outline how structural and functional genomics efforts provided valuable insights into the functions of viral proteins and revealed intricate details of the archaeal virus-host interactions. We then highlight recent metagenomics studies, which provided a glimpse at the diversity of uncultivated viruses associated with the ubiquitous archaea in the oceans, including Thaumarchaeota, Marine Group II Euryarchaeota, and others. These findings, combined with the recent discovery that archaeal viruses mediate a rapid turnover of thaumarchaea in the deep sea ecosystems, illuminate the prominent role of these viruses in the biosphere. Finally, we discuss the origins and evolution of archaeal viruses and emphasize the evolutionary relationships between viruses and non-viral mobile genetic elements. Further exploration of the archaeal virus diversity as well as functional studies on diverse virus-host systems are bound to uncover novel, unexpected facets of the archaeal virome.
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Affiliation(s)
- Mart Krupovic
- Department of Microbiology, Institut Pasteur, 25 rue du Dr. Roux, Paris 75015, Paris, France.
| | | | - Jaime Iranzo
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD, USA
| | - David Prangishvili
- Department of Microbiology, Institut Pasteur, 25 rue du Dr. Roux, Paris 75015, Paris, France
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD, USA
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24
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A plasmid from an Antarctic haloarchaeon uses specialized membrane vesicles to disseminate and infect plasmid-free cells. Nat Microbiol 2017; 2:1446-1455. [PMID: 28827601 DOI: 10.1038/s41564-017-0009-2] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 07/17/2017] [Indexed: 11/08/2022]
Abstract
The major difference between viruses and plasmids is the mechanism of transferring their genomic information between host cells. Here, we describe the archaeal plasmid pR1SE from an Antarctic species of haloarchaea that transfers via a mechanism similar to a virus. pR1SE encodes proteins that are found in regularly shaped membrane vesicles, and the vesicles enclose the plasmid DNA. The released vesicles are capable of infecting a plasmid-free strain, which then gains the ability to produce plasmid-containing vesicles. pR1SE can integrate and replicate as part of the host genome, resolve out with fragments of host DNA incorporated or portions of the plasmid left behind, form vesicles and transfer to new hosts. The pR1SE mechanism of transfer of DNA could represent the predecessor of a strategy used by viruses to pass on their genomic DNA and fulfil roles in gene exchange, supporting a strong evolutionary connection between plasmids and viruses.
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25
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Abstract
Viruses have impacted the biosphere in numerous ways since the dawn of life. However, the evolution, genetic, structural, and taxonomic diversity of viruses remain poorly understood, in part because sparse sampling of the virosphere has concentrated mostly on exploring the abundance and diversity of dsDNA viruses. Furthermore, viral genomes are highly diverse, and using only the current sequence-based methods for classifying viruses and studying their phylogeny is complicated. Here we describe a virus, FLiP (Flavobacterium-infecting, lipid-containing phage), with a circular ssDNA genome and an internal lipid membrane enclosed in the icosahedral capsid. The 9,174-nt-long genome showed limited sequence similarity to other known viruses. The genetic data imply that this virus might use replication mechanisms similar to those found in other ssDNA replicons. However, the structure of the viral major capsid protein, elucidated at near-atomic resolution using cryo-electron microscopy, is strikingly similar to that observed in dsDNA viruses of the PRD1-adenovirus lineage, characterized by a major capsid protein bearing two β-barrels. The strong similarity between FLiP and another member of the structural lineage, bacteriophage PM2, extends to the capsid organization (pseudo T = 21 dextro) despite the difference in the genetic material packaged and the lack of significant sequence similarity.
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26
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Homologous Capsid Proteins Testify to the Common Ancestry of Retroviruses, Caulimoviruses, Pseudoviruses, and Metaviruses. J Virol 2017; 91:JVI.00210-17. [PMID: 28356531 DOI: 10.1128/jvi.00210-17] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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27
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Nasir A, Caetano-Anollés G. Identification of Capsid/Coat Related Protein Folds and Their Utility for Virus Classification. Front Microbiol 2017; 8:380. [PMID: 28344575 PMCID: PMC5344890 DOI: 10.3389/fmicb.2017.00380] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Accepted: 02/23/2017] [Indexed: 12/31/2022] Open
Abstract
The viral supergroup includes the entire collection of known and unknown viruses that roam our planet and infect life forms. The supergroup is remarkably diverse both in its genetics and morphology and has historically remained difficult to study and classify. The accumulation of protein structure data in the past few years now provides an excellent opportunity to re-examine the classification and evolution of viruses. Here we scan completely sequenced viral proteomes from all genome types and identify protein folds involved in the formation of viral capsids and virion architectures. Viruses encoding similar capsid/coat related folds were pooled into lineages, after benchmarking against published literature. Remarkably, the in silico exercise reproduced all previously described members of known structure-based viral lineages, along with several proposals for new additions, suggesting it could be a useful supplement to experimental approaches and to aid qualitative assessment of viral diversity in metagenome samples.
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Affiliation(s)
- Arshan Nasir
- Department of Crop Sciences, Evolutionary Bioinformatics Laboratory, University of Illinois at Urbana-ChampaignUrbana, IL, USA; Department of Biosciences, COMSATS Institute of Information TechnologyIslamabad, Pakistan
| | - Gustavo Caetano-Anollés
- Department of Crop Sciences, Evolutionary Bioinformatics Laboratory, University of Illinois at Urbana-Champaign Urbana, IL, USA
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28
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Coloma SE, Dienstbier A, Bamford DH, Sivonen K, Roine E, Hiltunen T. Newly isolatedNodulariaphage influences cyanobacterial community dynamics. Environ Microbiol 2017; 19:273-286. [DOI: 10.1111/1462-2920.13601] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 10/25/2016] [Accepted: 11/16/2016] [Indexed: 12/18/2022]
Affiliation(s)
- S. E. Coloma
- Department of Food and Environmental SciencesViikinkaari 9, 00014 University of HelsinkiHelsinki Finland
| | - A. Dienstbier
- Department of BiosciencesViikinkaari 9, 00014 University of HelsinkiHelsinki Finland
| | - D. H. Bamford
- Department of BiosciencesViikinkaari 9, 00014 University of HelsinkiHelsinki Finland
- Institute of BiotechnologyViikinkaari 9, 00014 University of HelsinkiHelsinki Finland
| | - K. Sivonen
- Department of Food and Environmental SciencesViikinkaari 9, 00014 University of HelsinkiHelsinki Finland
| | - E. Roine
- Department of BiosciencesViikinkaari 9, 00014 University of HelsinkiHelsinki Finland
- Institute of BiotechnologyViikinkaari 9, 00014 University of HelsinkiHelsinki Finland
| | - T. Hiltunen
- Department of Food and Environmental SciencesViikinkaari 9, 00014 University of HelsinkiHelsinki Finland
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29
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Abstract
The taxonomy of viruses represents a unique classification system that recognizes boundaries among at first sight a continuum of properties. Genome sequencing has brought into sharp debate the origin of viruses, with RNA viruses perhaps having a separate evolutionary lineage. The criteria adopted for assessing the causal linkage between virus and disease deviates from those normally adopted for bacterial diseases and reflects those unique properties that underlie the principles of virus classification.
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30
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Demina TA, Atanasova NS, Pietilä MK, Oksanen HM, Bamford DH. Vesicle-like virion of Haloarcula hispanica pleomorphic virus 3 preserves high infectivity in saturated salt. Virology 2016; 499:40-51. [DOI: 10.1016/j.virol.2016.09.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 09/01/2016] [Accepted: 09/03/2016] [Indexed: 12/26/2022]
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31
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Forterre P. To be or not to be alive: How recent discoveries challenge the traditional definitions of viruses and life. STUDIES IN HISTORY AND PHILOSOPHY OF BIOLOGICAL AND BIOMEDICAL SCIENCES 2016; 59:100-108. [PMID: 26996409 DOI: 10.1016/j.shpsc.2016.02.013] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 02/27/2016] [Indexed: 06/05/2023]
Abstract
Three major discoveries have recently profoundly modified our perception of the viral world: molecular ecologists have shown that viral particles are more abundant than cells in natural environments; structural biologists have shown that some viruses from the three domains of life, Bacteria, Eukarya and Archaea, are evolutionarily related, and microbiologists have discovered giant viruses that rival with cells in terms of size and gene content. I discuss here the scientific and philosophical impact of these discoveries on the debates over the definition, nature (living or not), and origin of viruses. I suggest that viruses have often been considered non-living, because they are traditionally assimilated to their virions. However, the term virus describes a biological process and should integrate all aspects of the viral reproduction cycle. It is especially important to focus on the intracellular part of this cycle, the virocell, when viral information is actively expressed and reproduced, allowing the emergence of new viral genes. The virocell concept theoretically removes roadblocks that prevent defining viruses as living organisms. However, defining a "living organism" remains challenging, as indicated by the case of organelles that evolved from intracellular bacteria. To bypass this problem, I suggest considering that all biological entities that actively participate in the process of life are living.
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Affiliation(s)
- Patrick Forterre
- Institut Pasteur, Unité de Biologie Moléculaire du Gène chez les Extrêmophiles, Département de Microbiologie, F-75015, Paris, France.
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Serrano-Solís V, Cocho G, José MV. Genomic signatures in viral sequences by in-frame and out-frame mutual information. J Theor Biol 2016; 403:1-9. [PMID: 27178876 DOI: 10.1016/j.jtbi.2016.05.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 04/25/2016] [Accepted: 05/03/2016] [Indexed: 11/28/2022]
Abstract
In order to understand the unique biology of viruses, we use the Mutual Information Function (MIF) to characterize 792 viral sequences comprising 458 viral whole genomes. A 3-base periodicity (3-bp) was observed only in DNA-viruses whereas RNA-viruses showed irregular patterns. The correlation of MIF values at frequencies of 3-bp (in-frame) with frequencies of 4 and 5bps (out-frame), turned out to be useful to distinguish viruses according to their respective taxonomic order, and whether they pertain to any of the three different kingdoms, Eubacteria, Archaea and Eukarya. The clustering of viruses was carried out by the use of a new statistics, namely, the pair of in- and out-frame values of the MIF. The clustering thus obtained turned out to be entirely consistent with the current viral taxonomy. As a result we were able to compare in a single plot both viral and cellular genomes unlike any given phylogenetic reconstruction.
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Affiliation(s)
| | - Germinal Cocho
- Instituto de Física, Universidad Nacional Autónoma de México (IFUNAM), Mexico.
| | - Marco V José
- Theoretical Biology Group, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México D.F. 04510, Mexico.
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Abstract
UNLABELLED Virus genomes are prone to extensive gene loss, gain, and exchange and share no universal genes. Therefore, in a broad-scale study of virus evolution, gene and genome network analyses can complement traditional phylogenetics. We performed an exhaustive comparative analysis of the genomes of double-stranded DNA (dsDNA) viruses by using the bipartite network approach and found a robust hierarchical modularity in the dsDNA virosphere. Bipartite networks consist of two classes of nodes, with nodes in one class, in this case genomes, being connected via nodes of the second class, in this case genes. Such a network can be partitioned into modules that combine nodes from both classes. The bipartite network of dsDNA viruses includes 19 modules that form 5 major and 3 minor supermodules. Of these modules, 11 include tailed bacteriophages, reflecting the diversity of this largest group of viruses. The module analysis quantitatively validates and refines previously proposed nontrivial evolutionary relationships. An expansive supermodule combines the large and giant viruses of the putative order "Megavirales" with diverse moderate-sized viruses and related mobile elements. All viruses in this supermodule share a distinct morphogenetic tool kit with a double jelly roll major capsid protein. Herpesviruses and tailed bacteriophages comprise another supermodule, held together by a distinct set of morphogenetic proteins centered on the HK97-like major capsid protein. Together, these two supermodules cover the great majority of currently known dsDNA viruses. We formally identify a set of 14 viral hallmark genes that comprise the hubs of the network and account for most of the intermodule connections. IMPORTANCE Viruses and related mobile genetic elements are the dominant biological entities on earth, but their evolution is not sufficiently understood and their classification is not adequately developed. The key reason is the characteristic high rate of virus evolution that involves not only sequence change but also extensive gene loss, gain, and exchange. Therefore, in the study of virus evolution on a large scale, traditional phylogenetic approaches have limited applicability and have to be complemented by gene and genome network analyses. We applied state-of-the art methods of such analysis to reveal robust hierarchical modularity in the genomes of double-stranded DNA viruses. Some of the identified modules combine highly diverse viruses infecting bacteria, archaea, and eukaryotes, in support of previous hypotheses on direct evolutionary relationships between viruses from the three domains of cellular life. We formally identify a set of 14 viral hallmark genes that hold together the genomic network.
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Archaeal Haloarcula californiae Icosahedral Virus 1 Highlights Conserved Elements in Icosahedral Membrane-Containing DNA Viruses from Extreme Environments. mBio 2016; 7:mBio.00699-16. [PMID: 27435460 PMCID: PMC4958249 DOI: 10.1128/mbio.00699-16] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Despite their high genomic diversity, all known viruses are structurally constrained to a limited number of virion morphotypes. One morphotype of viruses infecting bacteria, archaea, and eukaryotes is the tailless icosahedral morphotype with an internal membrane. Although it is considered an abundant morphotype in extreme environments, only seven such archaeal viruses are known. Here, we introduce Haloarcula californiae icosahedral virus 1 (HCIV-1), a halophilic euryarchaeal virus originating from salt crystals. HCIV-1 also retains its infectivity under low-salinity conditions, showing that it is able to adapt to environmental changes. The release of progeny virions resulting from cell lysis was evidenced by reduced cellular oxygen consumption, leakage of intracellular ATP, and binding of an indicator ion to ruptured cell membranes. The virion contains at least 12 different protein species, lipids selectively acquired from the host cell membrane, and a 31,314-bp-long linear double-stranded DNA (dsDNA). The overall genome organization and sequence show high similarity to the genomes of archaeal viruses in the Sphaerolipoviridae family. Phylogenetic analysis based on the major conserved components needed for virion assembly—the major capsid proteins and the packaging ATPase—placed HCIV-1 along with the alphasphaerolipoviruses in a distinct, well-supported clade. On the basis of its virion morphology and sequence similarities, most notably, those of its core virion components, we propose that HCIV-1 is a member of the PRD1-adenovirus structure-based lineage together with other sphaerolipoviruses. This addition to the lineage reinforces the notion of the ancient evolutionary links observed between the viruses and further highlights the limits of the choices found in nature for formation of a virion. Under conditions of extreme salinity, the majority of the organisms present are archaea, which encounter substantial selective pressure, being constantly attacked by viruses. Regardless of the enormous viral sequence diversity, all known viruses can be clustered into a few structure-based viral lineages based on their core virion components. Our description of a new halophilic virus-host system adds significant insights into the largely unstudied field of archaeal viruses and, in general, of life under extreme conditions. Comprehensive molecular characterization of HCIV-1 shows that this icosahedral internal membrane-containing virus exhibits conserved elements responsible for virion organization. This places the virus neatly in the PRD1-adenovirus structure-based lineage. HCIV-1 further highlights the limited diversity of virus morphotypes despite the astronomical number of viruses in the biosphere. The observed high conservation in the core virion elements should be considered in addressing such fundamental issues as the origin and evolution of viruses and their interplay with their hosts.
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Abstract
Mycobacteriophages—viruses of mycobacteria—provide insights into viral diversity and evolution as well as numerous tools for genetic dissection of Mycobacterium tuberculosis. Here we report the complete genome sequences of 61 mycobacteriophages newly isolated from environmental samples using Mycobacterium smegmatis mc2155 that expand our understanding of phage diversity.
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Abstract
Many plasmids have been described in Euryarchaeota, one of the three major archaeal phyla, most of them in salt-loving haloarchaea and hyperthermophilic Thermococcales. These plasmids resemble bacterial plasmids in terms of size (from small plasmids encoding only one gene up to large megaplasmids) and replication mechanisms (rolling circle or theta). Some of them are related to viral genomes and form a more or less continuous sequence space including many integrated elements. Plasmids from Euryarchaeota have been useful for designing efficient genetic tools for these microorganisms. In addition, they have also been used to probe the topological state of plasmids in species with or without DNA gyrase and/or reverse gyrase. Plasmids from Euryarchaeota encode both DNA replication proteins recruited from their hosts and novel families of DNA replication proteins. Euryarchaeota form an interesting playground to test evolutionary hypotheses on the origin and evolution of viruses and plasmids, since a robust phylogeny is available for this phylum. Preliminary studies have shown that for different plasmid families, plasmids share a common gene pool and coevolve with their hosts. They are involved in gene transfer, mostly between plasmids and viruses present in closely related species, but rarely between cells from distantly related archaeal lineages. With few exceptions (e.g., plasmids carrying gas vesicle genes), most archaeal plasmids seem to be cryptic. Interestingly, plasmids and viral genomes have been detected in extracellular membrane vesicles produced by Thermococcales, suggesting that these vesicles could be involved in the transfer of viruses and plasmids between cells.
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Krupovic M, Cvirkaite-Krupovic V, Prangishvili D, Koonin EV. Evolution of an archaeal virus nucleocapsid protein from the CRISPR-associated Cas4 nuclease. Biol Direct 2015; 10:65. [PMID: 26514828 PMCID: PMC4625639 DOI: 10.1186/s13062-015-0093-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 10/26/2015] [Indexed: 12/23/2022] Open
Abstract
Abstract Many proteins of viruses infecting hyperthermophilic Crenarchaeota have no detectable homologs in current databases, hampering our understanding of viral evolution. We used sensitive database search methods and structural modeling to show that a nucleocapsid protein (TP1) of Thermoproteus tenax virus 1 (TTV1) is a derivative of the Cas4 nuclease, a component of the CRISPR-Cas adaptive immunity system that is encoded also by several archaeal viruses. In TTV1, the Cas4 gene was split into two, with the N-terminal portion becoming TP1, and lost some of the catalytic amino acid residues, apparently resulting in the inactivation of the nuclease. To our knowledge, this is the first described case of exaptation of an enzyme for a virus capsid protein function. Reviewers This article was reviewed by Vivek Anantharaman, Christine Orengo and Mircea Podar. For complete reviews, see the Reviewers’ reports section. Electronic supplementary material The online version of this article (doi:10.1186/s13062-015-0093-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Mart Krupovic
- Department of Microbiology, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Institut Pasteur, Paris, 75015, France.
| | - Virginija Cvirkaite-Krupovic
- Department of Microbiology, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Institut Pasteur, Paris, 75015, France.
| | - David Prangishvili
- Department of Microbiology, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Institut Pasteur, Paris, 75015, France.
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, 20894, USA.
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Krupovic M, Kuhn JH, Fischer MG. A classification system for virophages and satellite viruses. Arch Virol 2015; 161:233-47. [PMID: 26446887 DOI: 10.1007/s00705-015-2622-9] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 09/21/2015] [Indexed: 11/28/2022]
Abstract
Satellite viruses encode structural proteins required for the formation of infectious particles but depend on helper viruses for completing their replication cycles. Because of this unique property, satellite viruses that infect plants, arthropods, or mammals, as well as the more recently discovered satellite-like viruses that infect protists (virophages), have been grouped with other, so-called "sub-viral agents." For the most part, satellite viruses are therefore not classified. We argue that possession of a coat-protein-encoding gene and the ability to form virions are the defining features of a bona fide virus. Accordingly, all satellite viruses and virophages should be consistently classified within appropriate taxa. We propose to create four new genera - Albetovirus, Aumaivirus, Papanivirus, and Virtovirus - for positive-sense single-stranded (+) RNA satellite viruses that infect plants and the family Sarthroviridae, including the genus Macronovirus, for (+)RNA satellite viruses that infect arthopods. For double-stranded DNA virophages, we propose to establish the family Lavidaviridae, including two genera, Sputnikvirus and Mavirus.
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Affiliation(s)
- Mart Krupovic
- Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Department of Microbiology, Institut Pasteur, Paris, France.
| | - Jens H Kuhn
- Integrated Research Facility at Fort Detrick, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Fort Detrick, Frederick, MD, USA
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39
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Haloviruses of archaea, bacteria, and eukaryotes. Curr Opin Microbiol 2015; 25:40-8. [DOI: 10.1016/j.mib.2015.04.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 04/06/2015] [Indexed: 02/04/2023]
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40
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Jalasvuori M, Mattila S, Hoikkala V. Chasing the Origin of Viruses: Capsid-Forming Genes as a Life-Saving Preadaptation within a Community of Early Replicators. PLoS One 2015; 10:e0126094. [PMID: 25955384 PMCID: PMC4425637 DOI: 10.1371/journal.pone.0126094] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 03/29/2015] [Indexed: 12/31/2022] Open
Abstract
Virus capsids mediate the transfer of viral genetic information from one cell to another, thus the origin of the first viruses arguably coincides with the origin of the viral capsid. Capsid genes are evolutionarily ancient and their emergence potentially predated even the origin of first free-living cells. But does the origin of the capsid coincide with the origin of viruses, or is it possible that capsid-like functionalities emerged before the appearance of true viral entities? We set to investigate this question by using a computational simulator comprising primitive replicators and replication parasites within a compartment matrix. We observe that systems with no horizontal gene transfer between compartments collapse due to the rapidly emerging replication parasites. However, introduction of capsid-like genes that induce the movement of randomly selected genes from one compartment to another rescues life by providing the non-parasitic replicators a mean to escape their current compartments before the emergence of replication parasites. Capsid-forming genes can mediate the establishment of a stable meta-population where parasites cause only local tragedies but cannot overtake the whole community. The long-term survival of replicators is dependent on the frequency of horizontal transfer events, as systems with either too much or too little genetic exchange are doomed to succumb to replication-parasites. This study provides a possible scenario for explaining the origin of viral capsids before the emergence of genuine viruses: in the absence of other means of horizontal gene transfer between compartments, evolution of capsid-like functionalities may have been necessary for early life to prevail.
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Affiliation(s)
- Matti Jalasvuori
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
- * E-mail:
| | - Sari Mattila
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
| | - Ville Hoikkala
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
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Pope WH, Bowman CA, Russell DA, Jacobs-Sera D, Asai DJ, Cresawn SG, Jacobs WR, Hendrix RW, Lawrence JG, Hatfull GF. Whole genome comparison of a large collection of mycobacteriophages reveals a continuum of phage genetic diversity. eLife 2015; 4:e06416. [PMID: 25919952 PMCID: PMC4408529 DOI: 10.7554/elife.06416] [Citation(s) in RCA: 236] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Accepted: 03/19/2015] [Indexed: 01/21/2023] Open
Abstract
The bacteriophage population is large, dynamic, ancient, and genetically diverse. Limited genomic information shows that phage genomes are mosaic, and the genetic architecture of phage populations remains ill-defined. To understand the population structure of phages infecting a single host strain, we isolated, sequenced, and compared 627 phages of Mycobacterium smegmatis. Their genetic diversity is considerable, and there are 28 distinct genomic types (clusters) with related nucleotide sequences. However, amino acid sequence comparisons show pervasive genomic mosaicism, and quantification of inter-cluster and intra-cluster relatedness reveals a continuum of genetic diversity, albeit with uneven representation of different phages. Furthermore, rarefaction analysis shows that the mycobacteriophage population is not closed, and there is a constant influx of genes from other sources. Phage isolation and analysis was performed by a large consortium of academic institutions, illustrating the substantial benefits of a disseminated, structured program involving large numbers of freshman undergraduates in scientific discovery. DOI:http://dx.doi.org/10.7554/eLife.06416.001 Viruses are unable to replicate independently. To generate copies of itself, a virus must instead invade a target cell and commandeer that cell's replication machinery. Different viruses are able to invade different types of cell, and a group of viruses known as bacteriophages (or phages for short) replicate within bacteria. The enormous number and diversity of phages in the world means that they play an important role in virtually every ecosystem. Despite their importance, relatively little is known about how different phage populations are related to each other and how they evolved. Many phages contain their genetic information in the form of strands of DNA. Using genetic sequencing to find out where and how different genes are encoded in the DNA can reveal information about how different viruses are related to each other. These relationships are particularly complicated in phages, as they can exchange genes with other viruses and microbes. Previous studies comparing the genomes—the complete DNA sequence—of reasonably small numbers of phages that infect the Mycobacterium group of bacteria have found that the phages can be sorted into ‘clusters’ based on similarities in their genes and where these are encoded in their DNA. However, the number of phages investigated so far has been too small to conclude how different clusters are related. Are the clusters separate, or do they form a ‘continuum’ with different genes and DNA sequences shared between different clusters? Here, Pope, Bowman, Russell et al. compare the individual genomes of 627 bacteriophages that infect the bacterial species Mycobacterium smegmatis. This is by far the largest number of phage genomes analyzed from a single host species. The large number of genomes analyzed allowed a much clearer understanding of the complexity and diversity of these phages to be obtained. The isolation, sequencing and analysis of the hundreds of M. smegmatis bacteriophage genomes was performed by an integrated research and education program, called the Science Education Alliance Phage Hunters Advancing Genomics and Evolutionary Science (SEA-PHAGES) program. This enabled thousands of undergraduate students from different institutions to contribute to the phage discovery and sequencing project, and co-author the report. SEA-PHAGES therefore shows that it is possible to successfully incorporate genuine scientific research into an undergraduate course, and that doing so can benefit both the students and researchers involved. The results show that while the genomes could be categorized into 28 clusters, the genomes are not completely unrelated. Instead, a spread of diversity is seen, as genes and groups of genes are shared between different clusters. Pope, Bowman, Russell et al. further reveal that the phage population is in a constant state of change, and continuously acquires genes from other microorganisms and viruses. DOI:http://dx.doi.org/10.7554/eLife.06416.002
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Affiliation(s)
- Welkin H Pope
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, United States
| | - Charles A Bowman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, United States
| | - Daniel A Russell
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, United States
| | - Deborah Jacobs-Sera
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, United States
| | - David J Asai
- Howard Hughes Medical Institute, Chevy Chase, United States
| | - Steven G Cresawn
- Department of Biology, James Madison University, Harrisonburg, United States
| | - William R Jacobs
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, United States
| | - Roger W Hendrix
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, United States
| | - Jeffrey G Lawrence
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, United States
| | - Graham F Hatfull
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, United States
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Archaeal viruses multiply: temporal screening in a solar saltern. Viruses 2015; 7:1902-26. [PMID: 25866903 PMCID: PMC4411682 DOI: 10.3390/v7041902] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 03/16/2015] [Accepted: 03/31/2015] [Indexed: 11/16/2022] Open
Abstract
Hypersaline environments around the world are dominated by archaea and their viruses. To date, very little is known about these viruses and their interaction with the host strains when compared to bacterial and eukaryotic viruses. We performed the first culture-dependent temporal screening of haloarchaeal viruses and their hosts in the saltern of Samut Sakhon, Thailand, during two subsequent years (2009, 2010). Altogether we obtained 36 haloarchaeal virus isolates and 36 archaeal strains, significantly increasing the number of known archaeal virus isolates. Interestingly, the morphological distribution of our temporal isolates (head-tailed, pleomorphic, and icosahedral membrane-containing viruses) was similar to the outcome of our previous spatial survey supporting the observations of a global resemblance of halophilic microorganisms and their viruses. Myoviruses represented the most abundant virus morphotype with strikingly broad host ranges. The other viral morphotypes (siphoviruses, as well as pleomorphic and icosahedral internal membrane-containing viruses) were more host-specific. We also identified a group of Halorubrum strains highly susceptible to numerous different viruses (up to 26). This high virus sensitivity, the abundance of broad host range viruses, and the maintenance of infectivity over a period of one year suggest constant interplay of halophilic microorganisms and their viruses within an extreme environment.
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Krupovic M, Dolja VV, Koonin EV. Plant viruses of the Amalgaviridae family evolved via recombination between viruses with double-stranded and negative-strand RNA genomes. Biol Direct 2015; 10:12. [PMID: 25886840 PMCID: PMC4377212 DOI: 10.1186/s13062-015-0047-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 03/10/2015] [Indexed: 12/13/2022] Open
Abstract
Plant viruses of the recently recognized family Amalgaviridae have monopartite double-stranded (ds) RNA genomes and encode two proteins: an RNA-dependent RNA polymerase (RdRp) and a putative capsid protein (CP). Whereas the RdRp of amalgaviruses has been found to be most closely related to the RdRps of dsRNA viruses of the family Partitiviridae, the provenance of their CP remained obscure. Here we show that the CP of amalgaviruses is homologous to the nucleocapsid proteins of negative-strand RNA viruses of the genera Phlebovirus (Bunyaviridae) and Tenuivirus. The chimeric genomes of amalgaviruses are a testament to the effectively limitless gene exchange between viruses that shaped the evolution of the virosphere.
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Affiliation(s)
- Mart Krupovic
- Department of Microbiology, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Institut Pasteur, Paris, 75015, France.
| | - Valerian V Dolja
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331, USA.
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, 20894, USA.
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Koonin EV, Dolja VV, Krupovic M. Origins and evolution of viruses of eukaryotes: The ultimate modularity. Virology 2015; 479-480:2-25. [PMID: 25771806 PMCID: PMC5898234 DOI: 10.1016/j.virol.2015.02.039] [Citation(s) in RCA: 321] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 02/19/2015] [Accepted: 02/20/2015] [Indexed: 01/04/2023]
Abstract
Viruses and other selfish genetic elements are dominant entities in the biosphere, with respect to both physical abundance and genetic diversity. Various selfish elements parasitize on all cellular life forms. The relative abundances of different classes of viruses are dramatically different between prokaryotes and eukaryotes. In prokaryotes, the great majority of viruses possess double-stranded (ds) DNA genomes, with a substantial minority of single-stranded (ss) DNA viruses and only limited presence of RNA viruses. In contrast, in eukaryotes, RNA viruses account for the majority of the virome diversity although ssDNA and dsDNA viruses are common as well. Phylogenomic analysis yields tangible clues for the origins of major classes of eukaryotic viruses and in particular their likely roots in prokaryotes. Specifically, the ancestral genome of positive-strand RNA viruses of eukaryotes might have been assembled de novo from genes derived from prokaryotic retroelements and bacteria although a primordial origin of this class of viruses cannot be ruled out. Different groups of double-stranded RNA viruses derive either from dsRNA bacteriophages or from positive-strand RNA viruses. The eukaryotic ssDNA viruses apparently evolved via a fusion of genes from prokaryotic rolling circle-replicating plasmids and positive-strand RNA viruses. Different families of eukaryotic dsDNA viruses appear to have originated from specific groups of bacteriophages on at least two independent occasions. Polintons, the largest known eukaryotic transposons, predicted to also form virus particles, most likely, were the evolutionary intermediates between bacterial tectiviruses and several groups of eukaryotic dsDNA viruses including the proposed order "Megavirales" that unites diverse families of large and giant viruses. Strikingly, evolution of all classes of eukaryotic viruses appears to have involved fusion between structural and replicative gene modules derived from different sources along with additional acquisitions of diverse genes.
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Affiliation(s)
- Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA.
| | - Valerian V Dolja
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA.
| | - Mart Krupovic
- Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Department of Microbiology, Paris 75015, France.
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Koonin EV, Krupovic M, Yutin N. Evolution of double-stranded DNA viruses of eukaryotes: from bacteriophages to transposons to giant viruses. Ann N Y Acad Sci 2015; 1341:10-24. [PMID: 25727355 PMCID: PMC4405056 DOI: 10.1111/nyas.12728] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Diverse eukaryotes including animals and protists are hosts to a broad variety of viruses with double-stranded (ds) DNA genomes, from the largest known viruses, such as pandoraviruses and mimiviruses, to tiny polyomaviruses. Recent comparative genomic analyses have revealed many evolutionary connections between dsDNA viruses of eukaryotes, bacteriophages, transposable elements, and linear DNA plasmids. These findings provide an evolutionary scenario that derives several major groups of eukaryotic dsDNA viruses, including the proposed order “Megavirales,” adenoviruses, and virophages from a group of large virus-like transposons known as Polintons (Mavericks). The Polintons have been recently shown to encode two capsid proteins, suggesting that these elements lead a dual lifestyle with both a transposon and a viral phase and should perhaps more appropriately be named polintoviruses. Here, we describe the recently identified evolutionary relationships between bacteriophages of the family Tectiviridae, polintoviruses, adenoviruses, virophages, large and giant DNA viruses of eukaryotes of the proposed order “Megavirales,” and linear mitochondrial and cytoplasmic plasmids. We outline an evolutionary scenario under which the polintoviruses were the first group of eukaryotic dsDNA viruses that evolved from bacteriophages and became the ancestors of most large DNA viruses of eukaryotes and a variety of other selfish elements. Distinct lines of origin are detectable only for herpesviruses (from a different bacteriophage root) and polyoma/papillomaviruses (from single-stranded DNA viruses and ultimately from plasmids). Phylogenomic analysis of giant viruses provides compelling evidence of their independent origins from smaller members of the putative order “Megavirales,” refuting the speculations on the evolution of these viruses from an extinct fourth domain of cellular life.
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Affiliation(s)
- Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland
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Abstract
Studies on viruses parasitizing archaea reveal their specific nature and complete the tripartite division of the biosphere, indicating that each of the three domains of life-Archaea, Bacteria, and Eukarya-has its own set of associated DNA viruses. I argue that the remarkable morphotypical diversity of archaea-specific viruses could have originated from diverse viral archetypes that predated the divergence of the three domains of cellular life. It is possible that the descendants of many of these viral archetypes are able to parasitize extant archaea owing to their ability to evade archaea-specific defenses against virus infection, specifically the defenses linked to the evolution of cell envelope structure.
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Krupovic M, Forterre P. Single-stranded DNA viruses employ a variety of mechanisms for integration into host genomes. Ann N Y Acad Sci 2015; 1341:41-53. [PMID: 25675979 DOI: 10.1111/nyas.12675] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Single-stranded DNA (ssDNA) viruses are widespread in the environment and include economically, medically, and ecologically important pathogens. Recently, it has been discovered that ssDNA virus genomes are also prevalent in the chromosomes of their bacterial, archaeal, and eukaryotic hosts. Sequences originating from viruses of the families Parvoviridae, Circoviridae, and Geminiviridae are particularly widespread in the genomes of eukaryotes, where they are often fossilized as endogenous viral elements. ssDNA viruses have evolved diverse mechanisms to invade cellular genomes, and these principally vary between viruses infecting bacteria/archaea and eukaryotes. Filamentous bacteriophages (Inoviridae) use at least three major mechanisms of integration. Some of these phages encode integrases of serine or tyrosine recombinase superfamilies, while others utilize DDE transposases of the IS3, IS30, or IS110/IS492 families, whereas some inoviruses, and possibly certain members of the Microviridae, hijack the host XerCD recombination machinery. By contrast, eukaryotic viruses for integration rely on the endonuclease activity of their rolling-circle replication-initiation proteins, mimicking the mechanisms used by some bacterial transposons. Certain bacterial and eukaryotic ssDNA viruses have embraced a transposon-like means of propagation, with occasionally dramatic effects on host genome evolution. Here, we review the diversity of experimentally verified and hypothetical mechanisms of genome integration employed by ssDNA viruses, and consider the evolutionary implications of these processes, particularly in the emergence of novel virus groups.
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Affiliation(s)
- Mart Krupovic
- Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Paris, France
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Virus evolution toward limited dependence on nonessential functions of the host: the case of bacteriophage SPP1. J Virol 2014; 89:2875-83. [PMID: 25540376 DOI: 10.1128/jvi.03540-14] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED All viruses are obligate intracellular parasites and depend on certain host cell functions for multiplication. However, the extent of such dependence and the exact nature of the functions provided by the host cell remain poorly understood. Here, we investigated if nonessential Bacillus subtilis genes are necessary for multiplication of bacteriophage SPP1. Screening of a collection of 2,514 single-gene knockouts of nonessential B. subtilis genes yielded only a few genes necessary for efficient SPP1 propagation. Among these were genes belonging to the yuk operon, which codes for the Esat-6-like secretion system, including the SPP1 receptor protein YueB. In addition, we found that SPP1 multiplication was negatively affected by the absence of two other genes, putB and efp. The gene efp encodes elongation factor P, which enhances ribosome activity by alleviating translational stalling during the synthesis of polyproline-containing proteins. PutB is an enzyme involved in the proline degradation pathway that is required for infection in the post-exponential growth phase of B. subtilis, when the bacterium undergoes a complex genetic reprogramming. The putB knockout shortens significantly the window of opportunity for SPP1 infection during the host cell life cycle. This window is a critical parameter for competitive phage multiplication in the soil environment, where B. subtilis rarely meets conditions for exponential growth. Our results in combination with those reported for other virus-host systems suggest that bacterial viruses have evolved toward limited dependence on nonessential host functions. IMPORTANCE A successful viral infection largely depends on the ability of the virus to hijack cellular machineries and to redirect the flow of building blocks and energy resources toward viral progeny production. However, the specific virus-host interactions underlying this fundamental transformation are poorly understood. Here, we report on the first systematic analysis of virus-host cross talk during bacteriophage infection in Gram-positive bacteria. We show that lytic bacteriophage SPP1 is remarkably independent of nonessential genes of its host, Bacillus subtilis, with only a few cellular genes being necessary for efficient phage propagation. We hypothesize that such limited dependence of the virus on its host results from a constant "evolutionary arms race" and might be much more widespread than currently thought.
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49
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Abstract
Polintons (also known as Mavericks) are large DNA transposons that are widespread in the genomes of eukaryotes. We have recently shown that Polintons encode virus capsid proteins, which suggests that these transposons might form virions, at least under some conditions. In this Opinion article, we delineate the evolutionary relationships among bacterial tectiviruses, Polintons, adenoviruses, virophages, large and giant DNA viruses of eukaryotes of the proposed order 'Megavirales', and linear mitochondrial and cytoplasmic plasmids. We hypothesize that Polintons were the first group of eukaryotic double-stranded DNA viruses to evolve from bacteriophages and that they gave rise to most large DNA viruses of eukaryotes and various other selfish genetic elements.
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50
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Luk AWS, Williams TJ, Erdmann S, Papke RT, Cavicchioli R. Viruses of haloarchaea. Life (Basel) 2014; 4:681-715. [PMID: 25402735 PMCID: PMC4284463 DOI: 10.3390/life4040681] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 10/23/2014] [Accepted: 10/24/2014] [Indexed: 12/26/2022] Open
Abstract
In hypersaline environments, haloarchaea (halophilic members of the Archaea) are the dominant organisms, and the viruses that infect them, haloarchaeoviruses are at least ten times more abundant. Since their discovery in 1974, described haloarchaeoviruses include head-tailed, pleomorphic, spherical and spindle-shaped morphologies, representing Myoviridae, Siphoviridae, Podoviridae, Pleolipoviridae, Sphaerolipoviridae and Fuselloviridae families. This review overviews current knowledge of haloarchaeoviruses, providing information about classification, morphotypes, macromolecules, life cycles, genetic manipulation and gene regulation, and host-virus responses. In so doing, the review incorporates knowledge from laboratory studies of isolated viruses, field-based studies of environmental samples, and both genomic and metagenomic analyses of haloarchaeoviruses. What emerges is that some haloarchaeoviruses possess unique morphological and life cycle properties, while others share features with other viruses (e.g., bacteriophages). Their interactions with hosts influence community structure and evolution of populations that exist in hypersaline environments as diverse as seawater evaporation ponds, to hot desert or Antarctic lakes. The discoveries of their wide-ranging and important roles in the ecology and evolution of hypersaline communities serves as a strong motivator for future investigations of both laboratory-model and environmental systems.
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Affiliation(s)
- Alison W S Luk
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales 2052, Australia.
| | - Timothy J Williams
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales 2052, Australia.
| | - Susanne Erdmann
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales 2052, Australia.
| | - R Thane Papke
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269-3125, USA.
| | - Ricardo Cavicchioli
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales 2052, Australia.
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