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New virus isolates from Italian hydrothermal environments underscore the biogeographic pattern in archaeal virus communities. ISME JOURNAL 2020; 14:1821-1833. [PMID: 32322010 DOI: 10.1038/s41396-020-0653-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 03/28/2020] [Accepted: 03/31/2020] [Indexed: 12/22/2022]
Abstract
Viruses of hyperthermophilic archaea represent one of the least understood parts of the virosphere, showing little genomic and morphological similarity to viruses of bacteria or eukaryotes. Here, we investigated virus diversity in the active sulfurous fields of the Campi Flegrei volcano in Pozzuoli, Italy. Virus-like particles displaying eight different morphotypes, including lemon-shaped, droplet-shaped and bottle-shaped virions, were observed and five new archaeal viruses proposed to belong to families Rudiviridae, Globuloviridae and Tristromaviridae were isolated and characterized. Two of these viruses infect neutrophilic hyperthermophiles of the genus Pyrobaculum, whereas the remaining three have rod-shaped virions typical of the family Rudiviridae and infect acidophilic hyperthermophiles belonging to three different genera of the order Sulfolobales, namely, Saccharolobus, Acidianus, and Metallosphaera. Notably, Metallosphaera rod-shaped virus 1 is the first rudivirus isolated on Metallosphaera species. Phylogenomic analysis of the newly isolated and previously sequenced rudiviruses revealed a clear biogeographic pattern, with all Italian rudiviruses forming a monophyletic clade, suggesting geographical structuring of virus communities in extreme geothermal environments. Analysis of the CRISPR spacers suggests that isolated rudiviruses have experienced recent host switching across the genus boundary, potentially to escape the targeting by CRISPR-Cas immunity systems. Finally, we propose a revised classification of the Rudiviridae family, with the establishment of six new genera. Collectively, our results further show that high-temperature continental hydrothermal systems harbor a highly diverse virome and shed light on the evolution of archaeal viruses.
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2
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R-loop-forming Sequences Analysis in Thousands of Viral Genomes Identify A New Common Element in Herpesviruses. Sci Rep 2020; 10:6389. [PMID: 32286400 PMCID: PMC7156643 DOI: 10.1038/s41598-020-63101-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 03/20/2020] [Indexed: 11/16/2022] Open
Abstract
R-loops are RNA-DNA hybrid sequences that are emerging players in various biological processes, occurring in both prokaryotic and eukaryotic cells. In viruses, R-loop investigation is limited and functional importance is poorly understood. Here, we performed a computational approach to investigate prevalence, distribution, and location of R-loop forming sequences (RLFS) across more than 6000 viral genomes. A total of 14637 RLFS loci were identified in 1586 viral genomes. Over 70% of RLFS-positive genomes are dsDNA viruses. In the order Herpesvirales, RLFS were presented in all members whereas no RLFS was predicted in the order Ligamenvirales. Analysis of RLFS density in all RLFS-positive genomes revealed unusually high RLFS densities in herpesvirus genomes, with RLFS densities particularly enriched within repeat regions such as the terminal repeats (TRs). RLFS in TRs are positionally conserved between herpesviruses. Validating the computationally-identified RLFS, R-loop formation was experimentally confirmed in the TR and viral Bcl-2 promoter of Kaposi sarcoma-associated herpesvirus (KSHV). These predictions and validations support future analysis of RLFS in regulating the replication, transcription, and genome maintenance of herpesviruses.
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3
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Abstract
One of the most prominent features of archaea is the extraordinary diversity of their DNA viruses. Many archaeal viruses differ substantially in morphology from bacterial and eukaryotic viruses and represent unique virus families. The distinct nature of archaeal viruses also extends to the gene composition and architectures of their genomes and the properties of the proteins that they encode. Environmental research has revealed prominent roles of archaeal viruses in influencing microbial communities in ocean ecosystems, and recent metagenomic studies have uncovered new groups of archaeal viruses that infect extremophiles and mesophiles in diverse habitats. In this Review, we summarize recent advances in our understanding of the genomic and morphological diversity of archaeal viruses and the molecular biology of their life cycles and virus-host interactions, including interactions with archaeal CRISPR-Cas systems. We also examine the potential origins and evolution of archaeal viruses and discuss their place in the global virosphere.
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Formation of a Viral Replication Focus in Sulfolobus Cells Infected by the Rudivirus Sulfolobus islandicus Rod-Shaped Virus 2. J Virol 2017; 91:JVI.00486-17. [PMID: 28424282 DOI: 10.1128/jvi.00486-17] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 04/11/2017] [Indexed: 01/05/2023] Open
Abstract
Viral factories are compartmentalized centers for viral replication and assembly in infected eukaryotic cells. Here, we report the formation of a replication focus by prototypical archaeal Sulfolobus islandicus rod-shaped virus 2 (SIRV2) in the model archaeon Sulfolobus This rod-shaped virus belongs to the viral family Rudiviridae, carrying linear double-stranded DNA (dsDNA) genomes, which are very common in geothermal environments. We demonstrate that SIRV2 DNA synthesis is confined to a focus near the periphery of infected cells. Moreover, viral and cellular replication proteins are recruited to, and concentrated in, the viral replication focus. Furthermore, we show that of the four host DNA polymerases (DNA polymerase I [Dpo1] to Dpo4), only Dpo1 participates in viral DNA synthesis. This constitutes the first report of the formation of a viral replication focus in archaeal cells, suggesting that organization of viral replication in foci is a widespread strategy employed by viruses of the three domains of life.IMPORTANCE The organization of viral replication in foci or viral factories has been mostly described for different eukaryotic viruses and for several bacteriophages. This work constitutes the first report of the formation of a viral replication center by a virus infecting members of the Archaea domain.
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Abstract
Why some viruses are enveloped while others lack an outer lipid bilayer is a major question in viral evolution but one that has received relatively little attention. The viral envelope serves several functions, including protecting the RNA or DNA molecule(s), evading recognition by the immune system, and facilitating virus entry. Despite these commonalities, viral envelopes come in a wide variety of shapes and configurations. The evolution of the viral envelope is made more puzzling by the fact that nonenveloped viruses are able to infect a diverse range of hosts across the tree of life. We reviewed the entry, transmission, and exit pathways of all (101) viral families on the 2013 International Committee on Taxonomy of Viruses (ICTV) list. By doing this, we revealed a strong association between the lack of a viral envelope and the presence of a cell wall in the hosts these viruses infect. We were able to propose a new hypothesis for the existence of enveloped and nonenveloped viruses, in which the latter represent an adaptation to cells surrounded by a cell wall, while the former are an adaptation to animal cells where cell walls are absent. In particular, cell walls inhibit viral entry and exit, as well as viral transport within an organism, all of which are critical waypoints for successful infection and spread. Finally, we discuss how this new model for the origin of the viral envelope impacts our overall understanding of virus evolution.
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Gudbergsdóttir SR, Menzel P, Krogh A, Young M, Peng X. Novel viral genomes identified from six metagenomes reveal wide distribution of archaeal viruses and high viral diversity in terrestrial hot springs. Environ Microbiol 2015; 18:863-74. [PMID: 26439881 DOI: 10.1111/1462-2920.13079] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 09/30/2015] [Indexed: 11/27/2022]
Abstract
Limited by culture-dependent methods the number of viruses identified from thermophilic Archaea and Bacteria is still very small. In this study we retrieved viral sequences from six hot spring metagenomes isolated worldwide, revealing a wide distribution of four archaeal viral families, Ampullaviridae, Bicaudaviridae, Lipothrixviridae and Rudiviridae. Importantly, we identified 10 complete or near complete viral genomes allowing, for the first time, an assessment of genome conservation and evolution of the Ampullaviridae family as well as Sulfolobus Monocaudavirus 1 (SMV1)-related viruses. Among the novel genomes, one belongs to a putative thermophilic virus infecting the bacterium Hydrogenobaculum, for which no virus has been reported in the literature. Moreover, a high viral diversity was observed in the metagenomes, especially among the Lipothrixviridae, as indicated by the large number of unique contigs and the lack of a completely assembled genome for this family. This is further supported by the large number of novel genes in the complete and partial genomes showing no sequence similarities to public databases. CRISPR analysis revealed hundreds of novel CRISPR loci and thousands of novel CRISPR spacers from each metagenome, reinforcing the notion of high viral diversity in the thermal environment.
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Affiliation(s)
| | - Peter Menzel
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, Copenhagen N, DK-2200, Denmark
| | - Anders Krogh
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, Copenhagen N, DK-2200, Denmark
| | - Mark Young
- Plant Sciences and Plant Pathology, Montana State University, Bozeman, MT, 59717-3150, USA
| | - Xu Peng
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, Copenhagen N, DK-2200, Denmark
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7
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Abstract
SUMMARY Research on archaeal extrachromosomal genetic elements (ECEs) has progressed rapidly in the past decade. To date, over 60 archaeal viruses and 60 plasmids have been isolated. These archaeal viruses exhibit an exceptional diversity in morphology, with a wide array of shapes, such as spindles, rods, filaments, spheres, head-tails, bottles, and droplets, and some of these new viruses have been classified into one order, 10 families, and 16 genera. Investigation of model archaeal viruses has yielded important insights into mechanisms underlining various steps in the viral life cycle, including infection, DNA replication and transcription, and virion egression. Many of these mechanisms are unprecedented for any known bacterial or eukaryal viruses. Studies of plasmids isolated from different archaeal hosts have also revealed a striking diversity in gene content and innovation in replication strategies. Highly divergent replication proteins are identified in both viral and plasmid genomes. Genomic studies of archaeal ECEs have revealed a modular sequence structure in which modules of DNA sequence are exchangeable within, as well as among, plasmid families and probably also between viruses and plasmids. In particular, it has been suggested that ECE-host interactions have shaped the coevolution of ECEs and their archaeal hosts. Furthermore, archaeal hosts have developed defense systems, including the innate restriction-modification (R-M) system and the adaptive CRISPR (clustered regularly interspaced short palindromic repeats) system, to restrict invasive plasmids and viruses. Together, these interactions permit a delicate balance between ECEs and their hosts, which is vitally important for maintaining an innovative gene reservoir carried by ECEs. In conclusion, while research on archaeal ECEs has just started to unravel the molecular biology of these genetic entities and their interactions with archaeal hosts, it is expected to accelerate in the next decade.
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Guo Y, Kragelund BB, White MF, Peng X. Functional Characterization of a Conserved Archaeal Viral Operon Revealing Single-Stranded DNA Binding, Annealing and Nuclease Activities. J Mol Biol 2015; 427:2179-91. [DOI: 10.1016/j.jmb.2015.03.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 03/17/2015] [Accepted: 03/18/2015] [Indexed: 11/15/2022]
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9
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Snyder JC, Bolduc B, Young MJ. 40 Years of archaeal virology: Expanding viral diversity. Virology 2015; 479-480:369-78. [PMID: 25866378 DOI: 10.1016/j.virol.2015.03.031] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 02/07/2015] [Accepted: 03/17/2015] [Indexed: 10/23/2022]
Abstract
The first archaeal virus was isolated over 40 years ago prior to the recognition of the three domain structure of life. In the ensuing years, our knowledge of Archaea and their viruses has increased, but they still remain the most mysterious of life's three domains. Currently, over 100 archaeal viruses have been discovered, but few have been described in biochemical or structural detail. However, those that have been characterized have revealed a new world of structural, biochemical and genetic diversity. Several model systems for studying archaeal virus-host interactions have been developed, revealing evolutionary linkages between viruses infecting the three domains of life, new viral lysis systems, and unusual features of host-virus interactions. It is likely that the study of archaeal viruses will continue to provide fertile ground for fundamental discoveries in virus diversity, structure and function.
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Affiliation(s)
- Jamie C Snyder
- Department of Biological Sciences, California State Polytechnic University - Pomona, Pomona, CA, USA
| | - Benjamin Bolduc
- Departments of Plant Sciences and Microbiology, Montana State University, Bozeman, MT, USA
| | - Mark J Young
- Departments of Plant Sciences and Microbiology, Montana State University, Bozeman, MT, USA.
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10
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Happonen LJ, Erdmann S, Garrett RA, Butcher SJ. Adenosine triphosphatases of thermophilic archaeal double-stranded DNA viruses. Cell Biosci 2014; 4:37. [PMID: 25105011 PMCID: PMC4124505 DOI: 10.1186/2045-3701-4-37] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 06/13/2014] [Indexed: 12/02/2022] Open
Abstract
Adenosine triphosphatases (ATPases) of double-stranded (ds) DNA archaeal viruses are structurally related to the AAA+ hexameric helicases and translocases. These ATPases have been implicated in viral life cycle functions such as DNA entry into the host, and viral genome packaging into preformed procapsids. We summarize bioinformatical analyses of a wide range of archaeal ATPases, and review the biochemical and structural properties of those archaeal ATPases that have measurable ATPase activity. We discuss their potential roles in genome delivery into the host, virus assembly and genome packaging in comparison to hexameric helicases and packaging motors from bacteriophages.
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Affiliation(s)
- Lotta J Happonen
- Department of Clinical Sciences, Division of Infection Medicine, Lund University, SE-221 84 Lund, Sweden
| | - Susanne Erdmann
- Archaea Centre, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark
| | - Roger A Garrett
- Archaea Centre, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark
| | - Sarah J Butcher
- Institute of Biotechnology, University of Helsinki, (Viikinkaari 1), P.O. Box 65, FI-00014 Helsinki, Finland
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11
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Abstract
The Archaea-and their viruses-remain the most enigmatic of life's three domains. Once thought to inhabit only extreme environments, archaea are now known to inhabit diverse environments. Even though the first archaeal virus was described over 40 years ago, only 117 archaeal viruses have been discovered to date. Despite this small number, these viruses have painted a portrait of enormous morphological and genetic diversity. For example, research centered around the various steps of the archaeal virus life cycle has led to the discovery of unique mechanisms employed by archaeal viruses during replication, maturation, and virion release. In many instances, archaeal virus proteins display very low levels of sequence homology to other proteins listed in the public database, and therefore, structural characterization of these proteins has played an integral role in functional assignment. These structural studies have not only provided insights into structure-function relationships but have also identified links between viruses across all three domains of life.
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Affiliation(s)
- Nikki Dellas
- Thermal Biology Institute and Departments of.,Plant Sciences and
| | - Jamie C Snyder
- Thermal Biology Institute and Departments of.,Plant Sciences and
| | - Benjamin Bolduc
- Thermal Biology Institute and Departments of.,Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717;
| | - Mark J Young
- Thermal Biology Institute and Departments of.,Plant Sciences and
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12
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Unveiling cell surface and type IV secretion proteins responsible for archaeal rudivirus entry. J Virol 2014; 88:10264-8. [PMID: 24965447 DOI: 10.1128/jvi.01495-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Sulfolobus mutants resistant to archaeal lytic virus Sulfolobus islandicus rod-shaped virus 2 (SIRV2) were isolated, and mutations were identified in two gene clusters, cluster sso3138 to sso3141 and cluster sso2386 and sso2387, encoding cell surface and type IV secretion proteins, respectively. The involvement of the mutations in the resistance was confirmed by genetic complementation. Blocking of virus entry into the mutants was demonstrated by the lack of early gene transcription, strongly supporting the idea of a role of the proteins in SIRV2 entry.
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13
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Li S, Yang J. System analysis of synonymous codon usage biases in archaeal virus genomes. J Theor Biol 2014; 355:128-39. [PMID: 24685889 PMCID: PMC7094158 DOI: 10.1016/j.jtbi.2014.03.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Revised: 03/11/2014] [Accepted: 03/12/2014] [Indexed: 12/30/2022]
Abstract
Recent studies of geothermally heated aquatic ecosystems have found widely divergent viruses with unusual morphotypes. Archaeal viruses isolated from these hot habitats usually have double-stranded DNA genomes, linear or circular, and can infect members of the Archaea domain. In this study, the synonymous codon usage bias (SCUB) and dinucleotide composition in the available complete archaeal virus genome sequences have been investigated. It was found that there is a significant variation in SCUB among different Archaeal virus species, which is mainly determined by the base composition. The outcome of correspondence analysis (COA) and Spearman׳s rank correlation analysis shows that codon usage of selected archaeal virus genes depends mainly on GC richness of genome, and the gene׳s function, albeit with smaller effects, also contributes to codon usage in this virus. Furthermore, this investigation reveals that aromaticity of each protein is also critical in affecting SCUB of these viral genes although it was less important than that of the mutational bias. Especially, mutational pressure may influence SCUB in SIRV1, SIRV2, ARV1, AFV1, and PhiCh1 viruses, whereas translational selection could play a leading role in HRPV1׳s SCUB. These conclusions not only can offer an insight into the codon usage biases of archaeal virus and subsequently the possible relationship between archaeal viruses and their host, but also may help in understanding the evolution of archaeal viruses and their gene classification, and more helpful to explore the origin of life and the evolution of biology. The SCUB of archaeal virus genes depends mainly on GC richness of genome. The mutational pressure is the main factor that influences SCUB. The aromaticity of each protein is also critical in affecting SCUB. The translational selection could play a leading role in HRPV1׳s SCUB. The mode is helpful to explore the origin of life and the evolution of biology.
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Affiliation(s)
- Sen Li
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Science, Nanjing University, Nanjing 210093, China
| | - Jie Yang
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Science, Nanjing University, Nanjing 210093, China.
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14
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Abstract
This review presents a personal account of research on archaeal viruses and describes many new viral species and families, demonstrating that viruses of Archaea constitute a distinctive part of the virosphere and display morphotypes that are not associated with the other two domains of life, Bacteria and Eukarya. I focus primarily on viruses that infect hyperthermophilic members of the phylum Crenarchaeota. These viruses' distinctiveness extends from their morphotypes to their genome sequences and the structures of the proteins they encode. Moreover, the mechanisms underlying the interactions of these viruses with their hosts also have unique features. Studies of archaeal viruses provide new perspectives concerning the nature, diversity, and evolution of virus-host interactions. Considering these studies, I associate the distinctions between bacterial and archaeal viruses with the fundamental differences in the envelope compositions of their host cells.
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15
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Pietilä MK, Demina TA, Atanasova NS, Oksanen HM, Bamford DH. Archaeal viruses and bacteriophages: comparisons and contrasts. Trends Microbiol 2014; 22:334-44. [PMID: 24647075 DOI: 10.1016/j.tim.2014.02.007] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 02/14/2014] [Accepted: 02/20/2014] [Indexed: 10/25/2022]
Abstract
Isolated archaeal viruses comprise only a few percent of all known prokaryotic viruses. Thus, the study of viruses infecting archaea is still in its early stages. Here we summarize the most recent discoveries of archaeal viruses utilizing a virion-centered view. We describe the known archaeal virion morphotypes and compare them to the bacterial counterparts, if such exist. Viruses infecting archaea are morphologically diverse and present some unique morphotypes. Although limited in isolate number, archaeal viruses reveal new insights into the viral world, such as deep evolutionary relationships between viruses that infect hosts from all three domains of life.
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Affiliation(s)
- Maija K Pietilä
- Institute of Biotechnology and Department of Biosciences, P.O. Box 56, Viikinkaari 5, 00014 University of Helsinki, Helsinki, Finland
| | - Tatiana A Demina
- Institute of Biotechnology and Department of Biosciences, P.O. Box 56, Viikinkaari 5, 00014 University of Helsinki, Helsinki, Finland
| | - Nina S Atanasova
- Institute of Biotechnology and Department of Biosciences, P.O. Box 56, Viikinkaari 5, 00014 University of Helsinki, Helsinki, Finland
| | - Hanna M Oksanen
- Institute of Biotechnology and Department of Biosciences, P.O. Box 56, Viikinkaari 5, 00014 University of Helsinki, Helsinki, Finland
| | - Dennis H Bamford
- Institute of Biotechnology and Department of Biosciences, P.O. Box 56, Viikinkaari 5, 00014 University of Helsinki, Helsinki, Finland.
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16
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Genomics and biology of Rudiviruses, a model for the study of virus-host interactions in Archaea. Biochem Soc Trans 2013; 41:443-50. [PMID: 23356326 DOI: 10.1042/bst20120313] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Archaeal viruses, especially viruses that infect hyperthermophilic archaea of the phylum Crenarchaeota, constitute one of the least understood parts of the virosphere. However, owing to recent substantial research efforts by several groups, archaeal viruses are starting to gradually reveal their secrets. In the present review, we summarize the current knowledge on one of the emerging model systems for studies on crenarchaeal viruses, the Rudiviridae. We discuss the recent advances towards understanding the function and structure of the proteins encoded by the rudivirus genomes, their role in the virus life cycle, and outline the directions for further research on this model system. In addition, a revised genome annotation of SIRV2 (Sulfolobus islandicus rod-shaped virus 2) is presented. Future studies on archaeal viruses, combined with the knowledge on viruses of bacteria and eukaryotes, should lead to a better global understanding of the diversity and evolution of virus-host interactions in the viral world.
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17
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Krupovic M, White MF, Forterre P, Prangishvili D. Postcards from the edge: structural genomics of archaeal viruses. Adv Virus Res 2013; 82:33-62. [PMID: 22420850 DOI: 10.1016/b978-0-12-394621-8.00012-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Ever since their discovery, archaeal viruses have fascinated biologists with their unusual virion morphotypes and their ability to thrive in extreme environments. Attempts to understand the biology of these viruses through genome sequence analysis were not efficient. Genomes of archaeoviruses proved to be terra incognita with only a few genes with predictable functions but uncertain provenance. In order to facilitate functional characterization of archaeal virus proteins, several research groups undertook a structural genomics approach. This chapter summarizes the outcome of these efforts. High-resolution structures of 30 proteins encoded by archaeal viruses have been solved so far. Some of these proteins possess new structural folds, whereas others display previously known topologies, albeit without detectable sequence similarity to their structural homologues. Structures of the major capsid proteins have illuminated intriguing evolutionary connections between viruses infecting hosts from different domains of life and also revealed new structural folds not yet observed in currently known bacterial and eukaryotic viruses. Structural studies, discussed here, have advanced our understanding of the archaeal virosphere and provided precious information on different aspects of biology of archaeal viruses and evolution of viruses in general.
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Affiliation(s)
- Mart Krupovic
- Department of Microbiology, Institut Pasteur, Molecular Biology of the Gene in Extremophiles Unit, Paris, France
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18
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Genome sequence of a novel archaeal rudivirus recovered from a mexican hot spring. GENOME ANNOUNCEMENTS 2013; 1:genomeA00040-12. [PMID: 23405288 PMCID: PMC3569270 DOI: 10.1128/genomea.00040-12] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 10/29/2012] [Indexed: 11/27/2022]
Abstract
We report the consensus genome sequence of a novel GC-rich rudivirus, designated SMR1 (Sulfolobales Mexican rudivirus 1), assembled from a high-throughput sequenced environmental sample from a hot spring in Los Azufres National Park in western Mexico.
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19
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A new proposed taxon for double-stranded DNA viruses, the order “Ligamenvirales”. Arch Virol 2012; 157:791-5. [DOI: 10.1007/s00705-012-1229-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Accepted: 12/09/2011] [Indexed: 11/26/2022]
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20
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Abstract
Since their discovery in the early 1980s, viruses that infect the third domain of life, the Archaea, have captivated our attention because of their virions' unusual morphologies and proteins, which lack homologues in extant databases. Moreover, the life cycles of these viruses have unusual features, as revealed by the recent discovery of a novel virus egress mechanism that involves the formation of specific pyramidal structures on the host cell surface. The available data elucidate the particular nature of the archaeal virosphere and shed light on questions concerning the origin and evolution of viruses and cells. In this review, we summarize the current knowledge of archeoviruses, their interaction with hosts and plasmids and their role in the evolution of life.
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Affiliation(s)
- Mery Pina
- Institut Pasteur, Molecular Biology of the Gene in Extremophiles Unit, Paris, France
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21
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Prangishvili D, Quax TEF. Exceptional virion release mechanism: one more surprise from archaeal viruses. Curr Opin Microbiol 2011; 14:315-20. [DOI: 10.1016/j.mib.2011.04.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Revised: 03/30/2011] [Accepted: 04/07/2011] [Indexed: 10/18/2022]
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22
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A dimeric Rep protein initiates replication of a linear archaeal virus genome: implications for the Rep mechanism and viral replication. J Virol 2010; 85:925-31. [PMID: 21068244 DOI: 10.1128/jvi.01467-10] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The Rudiviridae are a family of rod-shaped archaeal viruses with covalently closed, linear double-stranded DNA (dsDNA) genomes. Their replication mechanisms remain obscure, although parallels have been drawn to the Poxviridae and other large cytoplasmic eukaryotic viruses. Here we report that a protein encoded in the 34-kbp genome of the rudivirus SIRV1 is a member of the replication initiator (Rep) superfamily of proteins, which initiate rolling-circle replication (RCR) of diverse viruses and plasmids. We show that SIRV Rep nicks the viral hairpin terminus, forming a covalent adduct between an active-site tyrosine and the 5' end of the DNA, releasing a 3' DNA end as a primer for DNA synthesis. The enzyme can also catalyze the joining reaction that is necessary to reseal the DNA hairpin and terminate replication. The dimeric structure points to a simple mechanism through which two closely positioned active sites, each with a single tyrosine residue, work in tandem to catalyze DNA nicking and joining. We propose a novel mechanism for rudivirus DNA replication, incorporating the first known example of a Rep protein that is not linked to RCR. The implications for Rep protein function and viral replication are discussed.
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The Sulfolobus rod-shaped virus 2 encodes a prominent structural component of the unique virion release system in Archaea. Virology 2010; 404:1-4. [PMID: 20488501 DOI: 10.1016/j.virol.2010.04.020] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Revised: 03/08/2010] [Accepted: 04/20/2010] [Indexed: 10/19/2022]
Abstract
Recently a unique mechanism of virion release was discovered in Archaea, different from lysis and egress systems of bacterial and eukaryotic viruses. It involves formation of pyramidal structures on the host cell surface that rupture the S-layer and by opening outwards, create apertures through which mature virions escape the cell. Here we present results of a protein analysis of Sulfolobus islandicus cells infected with the rudivirus SIRV2, which enable us to postulate SIRV2-encoded protein P98 as the major constituent of these exceptional cellular ultrastructures.
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Mochizuki T, Yoshida T, Tanaka R, Forterre P, Sako Y, Prangishvili D. Diversity of viruses of the hyperthermophilic archaeal genus Aeropyrum, and isolation of the Aeropyrum pernix bacilliform virus 1, APBV1, the first representative of the family Clavaviridae. Virology 2010; 402:347-54. [PMID: 20430412 DOI: 10.1016/j.virol.2010.03.046] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Revised: 01/19/2010] [Accepted: 03/29/2010] [Indexed: 10/19/2022]
Abstract
We have surveyed the morphological diversity of viruses infecting the archaeon Aeropyrum pernix, the most thermophilic species among aerobic organisms, growing optimally at 90 degrees C, and isolated and characterized a novel virus, Aeropyrum pernix bacilliform virus 1, APBV1. This is the first virus to be described of the genus Aeropyrum and the archaeal order Desulfurococcales. The virion of APBV1 has rigid bacilliform morphology, about 140x20nm, with one end pointed and the other rounded. It contains highly glycosylated single major protein and three minor proteins. The circular, double-stranded DNA genome comprising 5278bp is the smallest for known archaeal viruses. None of the 14 putative genes, all on the same DNA strand, shows significant similarity to sequences in the public databases. The APBV1 infection caused neither retardation of host growth nor lysis of host cells, and integration of the viral genome into the host chromosome was not detected. On the basis of unusual morphological and genomic properties, we propose to consider APBV1 as the first representative of a new viral family, the Clavaviridae.
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Affiliation(s)
- Tomohiro Mochizuki
- Institute Pasteur, Molecular Biology of the Gene in Extremophiles Unit, Department of Microbiology, F-75015 Paris, France
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25
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Abstract
Archaea often live in extreme, harsh environments such as acidic hot springs and hypersaline waters. To date, only two icosahedrally symmetric, membrane-containing archaeal viruses, SH1 and Sulfolobus turreted icosahedral virus (STIV), have been described in detail. We report the sequence and three-dimensional structure of a third such virus isolated from a hyperthermoacidophilic crenarchaeon, Sulfolobus strain G4ST-2. Characterization of this new isolate revealed it to be similar to STIV on the levels of genome and structural organization. The genome organization indicates that these two viruses have diverged from a common ancestor. Interestingly, the prominent surface turrets of the two viruses are strikingly different. By sequencing and mass spectrometry, we mapped several large insertions and deletions in the known structural proteins that could account for these differences and showed that both viruses can infect the same host. A combination of genomic and proteomic analyses revealed important new insights into the structural organization of these viruses and added to our limited knowledge of archaeal virus life cycles and host-cell interactions.
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26
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New, closely related haloarchaeal viral elements with different nucleic Acid types. J Virol 2010; 84:3682-9. [PMID: 20089654 DOI: 10.1128/jvi.01879-09] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During the search for haloarchaeal viruses, we isolated and characterized a new pleomorphic lipid-containing virus, Haloarcula hispanica pleomorphic virus 1 (HHPV-1), that infects the halophilic archaeon Haloarcula hispanica. The virus contains a circular double-stranded DNA genome of 8,082 bp in size. The organization of the genome shows remarkable synteny and amino acid sequence similarity to the genome and predicted proteins of the halovirus HRPV-1, a pleomorphic single-stranded DNA virus that infects a halophilic archaeon Halorubrum sp. Analysis of the two halovirus sequences, as well as the entire nucleotide sequence of the 10.8-kb pHK2-plasmid and a 12.6-kb chromosomal region in Haloferax volcanii, allows us to suggest a new group of closely related viruses with genomes of either single-stranded or double-stranded DNA. Currently, closely related viruses are considered to have the same genome type. Our observation clearly contradicts this categorization and indicates that we should reconsider the way we classify viruses. Our results also provide a new example of related viruses where the viral structural proteins have not diverged as much as the proteins associated with genome replication. This result further strengthens the proposal for higher-order classification to be based on virion architecture rather than on genome type or replication mechanism.
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Goulet A, Blangy S, Redder P, Prangishvili D, Felisberto-Rodrigues C, Forterre P, Campanacci V, Cambillau C. Acidianus filamentous virus 1 coat proteins display a helical fold spanning the filamentous archaeal viruses lineage. Proc Natl Acad Sci U S A 2009; 106:21155-60. [PMID: 19934032 PMCID: PMC2795548 DOI: 10.1073/pnas.0909893106] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Indexed: 11/18/2022] Open
Abstract
Acidianus filamentous virus 1 (AFV1), a member of the Lipothrixviridae family, infects the hyperthermophilic, acidophilic crenarchaeaon Acidianus hospitalis. The virion, covered with a lipidic outer shell, is 9,100-A long and contains a 20.8-kb linear dsDNA genome. We have identified the two major coat proteins of the virion (MCPs; 132 and 140 amino acids). They bind DNA and form filaments when incubated with linear dsDNA. A C-terminal domain is identified in their crystal structure with a four-helix-bundle fold. In the topological model of the virion filament core, the genomic dsDNA superhelix wraps around the AFV1-132 basic protein, and the AFV1-140 basic N terminus binds genomic DNA, while its lipophilic C-terminal domain is imbedded in the lipidic outer shell. The four-helix bundle fold of the MCPs from AFV1 is identical to that of the coat protein (CP) of Sulfolobus islandicus rod-shaped virus (SIRV), a member of the Rudiviridae family. Despite low sequence identity between these proteins, their high degree of structural similarity suggests that they could have derived from a common ancestor and could thus define an yet undescribed viral lineage.
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Affiliation(s)
- Adeline Goulet
- Architecture et Fonction des Macromolécules Biologiques, Centre national de la recherche scientifique and Universités Aix-Marseille I & II, Architecture et Fonction des Macromolécules Biologiques, Unité Mixte de Recherche 6098, Case 932, 163 avenue de Luminy, 13288 Marseille Cedex 9, France
| | - Stéphanie Blangy
- Architecture et Fonction des Macromolécules Biologiques, Centre national de la recherche scientifique and Universités Aix-Marseille I & II, Architecture et Fonction des Macromolécules Biologiques, Unité Mixte de Recherche 6098, Case 932, 163 avenue de Luminy, 13288 Marseille Cedex 9, France
| | - Peter Redder
- Institut Pasteur, Unité de Biologie Moléculaire du Gène chez les Extrêmophiles, 28 Rue du Dr Roux, 75724 Paris Cedex 15, France; and
| | - David Prangishvili
- Institut Pasteur, Unité de Biologie Moléculaire du Gène chez les Extrêmophiles, 28 Rue du Dr Roux, 75724 Paris Cedex 15, France; and
| | - Catarina Felisberto-Rodrigues
- Architecture et Fonction des Macromolécules Biologiques, Centre national de la recherche scientifique and Universités Aix-Marseille I & II, Architecture et Fonction des Macromolécules Biologiques, Unité Mixte de Recherche 6098, Case 932, 163 avenue de Luminy, 13288 Marseille Cedex 9, France
| | - Patrick Forterre
- Institut Pasteur, Unité de Biologie Moléculaire du Gène chez les Extrêmophiles, 28 Rue du Dr Roux, 75724 Paris Cedex 15, France; and
- Institut de Génétique et Microbiologie, Université Paris-Sud and Centre national de la recherche scientifique, Unité Mixte de Recherche 8621, 91405 Orsay Cedex, France
| | - Valérie Campanacci
- Architecture et Fonction des Macromolécules Biologiques, Centre national de la recherche scientifique and Universités Aix-Marseille I & II, Architecture et Fonction des Macromolécules Biologiques, Unité Mixte de Recherche 6098, Case 932, 163 avenue de Luminy, 13288 Marseille Cedex 9, France
| | - Christian Cambillau
- Architecture et Fonction des Macromolécules Biologiques, Centre national de la recherche scientifique and Universités Aix-Marseille I & II, Architecture et Fonction des Macromolécules Biologiques, Unité Mixte de Recherche 6098, Case 932, 163 avenue de Luminy, 13288 Marseille Cedex 9, France
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Mazaheri Nezhad Fard R, Barton MD, Heuzenroeder MW. Novel Bacteriophages in Enterococcus spp. Curr Microbiol 2009; 60:400-6. [PMID: 19967374 DOI: 10.1007/s00284-009-9555-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2009] [Accepted: 11/13/2009] [Indexed: 02/06/2023]
Abstract
Most of the bacteriophages (phages) currently reported in Enterococcus spp. belong to tailed families of bacteriophages Podoviridae, Siphoviridae, and Myoviridae. There is a little information on non-tailed bacteriophages isolated from enterococci. Samples of sewage and piggery effluents were tested on pig and chicken isolates of Enterococcus faecalis, E. faecium and E. gallinarum for lytic phages. In addition, isolates were exposed to mitomycin C to induce lysogenic phages. Bacteriophages that were detected were visualized by electron microscopy. Ten bacteriophages were of isometric shape with long flexible or non-flexible tails, while one had a long head with a long flexible tail; all contained double-stranded DNA molecules. Seven Polyhedral, filamentous, and pleomorphic-shaped phages containing DNA or RNA were also observed. The pleomorphic phages were droplet- or lemon-shaped in morphology. This study is the first report on polyhedral phages in Enterococcus spp. of animal origin and also the first report of filamentous and pleomorphic phages in enterococci.
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The single-stranded DNA genome of novel archaeal virus halorubrum pleomorphic virus 1 is enclosed in the envelope decorated with glycoprotein spikes. J Virol 2009; 84:788-98. [PMID: 19864380 DOI: 10.1128/jvi.01347-09] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Only a few archaeal viruses have been subjected to detailed structural analyses. Major obstacles have been the extreme conditions such as high salinity or temperature needed for the propagation of these viruses. In addition, unusual morphotypes of many archaeal viruses have made it difficult to obtain further information on virion architectures. We used controlled virion dissociation to reveal the structural organization of Halorubrum pleomorphic virus 1 (HRPV-1) infecting an extremely halophilic archaeal host. The single-stranded DNA genome is enclosed in a pleomorphic membrane vesicle without detected nucleoproteins. VP4, the larger major structural protein of HRPV-1, forms glycosylated spikes on the virion surface and VP3, the smaller major structural protein, resides on the inner surface of the membrane vesicle. Together, these proteins organize the structure of the membrane vesicle. Quantitative lipid comparison of HRPV-1 and its host Halorubrum sp. revealed that HRPV-1 acquires lipids nonselectively from the host cell membrane, which is typical of pleomorphic enveloped viruses.
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Guillière F, Peixeiro N, Kessler A, Raynal B, Desnoues N, Keller J, Delepierre M, Prangishvili D, Sezonov G, Guijarro JI. Structure, function, and targets of the transcriptional regulator SvtR from the hyperthermophilic archaeal virus SIRV1. J Biol Chem 2009; 284:22222-22237. [PMID: 19535331 PMCID: PMC2755947 DOI: 10.1074/jbc.m109.029850] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Revised: 06/04/2009] [Indexed: 11/06/2022] Open
Abstract
We have characterized the structure and the function of the 6.6-kDa protein SvtR (formerly called gp08) from the rod-shaped virus SIRV1, which infects the hyperthermophilic archaeon Sulfolobus islandicus that thrives at 85 degrees C in hot acidic springs. The protein forms a dimer in solution. The NMR solution structure of the protein consists of a ribbon-helix-helix (RHH) fold between residues 13 and 56 and a disordered N-terminal region (residues 1-12). The structure is very similar to that of bacterial RHH proteins despite the low sequence similarity. We demonstrated that the protein binds DNA and uses its beta-sheet face for the interaction like bacterial RHH proteins. To detect all the binding sites on the 32.3-kb SIRV1 linear genome, we designed and performed a global genome-wide search of targets based on a simplified electrophoretic mobility shift assay. Four targets were recognized by the protein. The strongest binding was observed with the promoter of the gene coding for a virion structural protein. When assayed in a host reconstituted in vitro transcription system, the protein SvtR (Sulfolobus virus transcription regulator) repressed transcription from the latter promoter, as well as from the promoter of its own gene.
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Affiliation(s)
- Florence Guillière
- From the Institut Pasteur, Unité de RMN des Biomolécules, CNRS URA 2185, 75015 Paris
| | - Nuno Peixeiro
- the Institut Pasteur, Unité de Biologie Moléculaire du Gène chez les Extrêmophiles, 75015 Paris
| | - Alexandra Kessler
- the Institut Pasteur, Unité de Biologie Moléculaire du Gène chez les Extrêmophiles, 75015 Paris
| | - Bertrand Raynal
- the Institut Pasteur, Plate-forme de Biophysique des Macromolécules et de leurs Interactions, 75015 Paris
| | - Nicole Desnoues
- the Institut Pasteur, Unité de Biologie Moléculaire du Gène chez les Extrêmophiles, 75015 Paris
| | - Jenny Keller
- the Institut de Biochimie et de Biophysique Moléculaire et Cellulaire, CNRS-UMR 8619, Université Paris 11, IFR115, Bâtiment 430, 91405 Orsay, and
| | - Muriel Delepierre
- From the Institut Pasteur, Unité de RMN des Biomolécules, CNRS URA 2185, 75015 Paris
| | - David Prangishvili
- the Institut Pasteur, Unité de Biologie Moléculaire du Gène chez les Extrêmophiles, 75015 Paris
| | - Guennadi Sezonov
- the Institut Pasteur, Unité de Biologie Moléculaire du Gène chez les Extrêmophiles, 75015 Paris
- the Université Pierre et Marie Curie, 4 place Jussieu, 75005 Paris, France
| | - J. Iñaki Guijarro
- From the Institut Pasteur, Unité de RMN des Biomolécules, CNRS URA 2185, 75015 Paris
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31
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Abstract
CPMV (cowpea mosaic virus), a plant virus, is a naturally occurring sphere-like nanoparticle, and is used as a synthon and/or template in bionanoscience. The virions formed by CPMV can be regarded as programmable nanobuilding blocks with a diameter of ∼30 nm. A range of molecules have been attached to this viral nanoscaffold, yielding stable nanoparticles that display multiple copies of the desired molecule. It has been shown that, in addition to surface amine groups, surface carboxy groups are also addressable, and a procedure has been developed that enables introduction of reactive thiols at the virion surface that avoids virus aggregation. Furthermore, the virions can be functionalized to form electroactive nanoparticles. Methods for the construction of arrays and multilayers, using a layer-by-layer approach, have been established. As proof of concept, for example, CPMV particles have been immobilized on surfaces and arranged in defined layers. Engineered variants of CPMV can be used as templates for mineralization with, for example, silica to give monodisperse robust silica nanoparticles of ∼32 nm. SIRV2 (Sulfolobus islandicus rod-shaped virus 2), is a robust archaeal virus, resistant to high temperature and low pH. SIRV2 can act as a template for site-selective and spatially controlled chemical modification. Both the ends and the body of the virus, or the ends only, can be chemically addressed; SIRV2 can be regarded as a structurally unique nanobuilding block.
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32
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Abstract
Little is known about the infection cycles of viruses infecting cells from Archaea, the third domain of life. Here, we demonstrate that the virions of the archaeal Sulfolobus islandicus rod-shaped virus 2 (SIRV2) are released from the host cell through a mechanism, involving the formation of specific cellular structures. Large pyramidal virus-induced protrusions transect the cell envelope at several positions, rupturing the S-layer; they eventually open out, thus creating large apertures through which virions escape the cell. We also demonstrate that massive degradation of the host chromosomes occurs because of virus infection, and that virion assembly occurs in the cytoplasm. Furthermore, intracellular viral DNA is visualized by flow cytometry. The results show that SIRV2 is a lytic virus, and that the host cell dies as a consequence of elaborated mechanisms orchestrated by the virus. The generation of specific cellular structures for a distinct step of virus life cycle is known in eukaryal virus-host systems but is unprecedented in cells from other domains.
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33
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Identification of a tail assembly gene cluster from deep-sea thermophilic bacteriophage GVE2. Virus Genes 2009; 38:507-14. [DOI: 10.1007/s11262-009-0351-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2008] [Accepted: 03/15/2009] [Indexed: 10/21/2022]
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34
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Stygiolobus rod-shaped virus and the interplay of crenarchaeal rudiviruses with the CRISPR antiviral system. J Bacteriol 2008; 190:6837-45. [PMID: 18723627 DOI: 10.1128/jb.00795-08] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A newly characterized archaeal rudivirus Stygiolobus rod-shaped virus (SRV), which infects a hyperthermophilic Stygiolobus species, was isolated from a hot spring in the Azores, Portugal. Its virions are rod-shaped, 702 (+/- 50) by 22 (+/- 3) nm in size, and nonenveloped and carry three tail fibers at each terminus. The linear double-stranded DNA genome contains 28,096 bp and an inverted terminal repeat of 1,030 bp. The SRV shows morphological and genomic similarities to the other characterized rudiviruses Sulfolobus rod-shaped virus 1 (SIRV1), SIRV2, and Acidianus rod-shaped virus 1, isolated from hot acidic springs of Iceland and Italy. The single major rudiviral structural protein is shown to generate long tubular structures in vitro of similar dimensions to those of the virion, and we estimate that the virion constitutes a single, superhelical, double-stranded DNA embedded into such a protein structure. Three additional minor conserved structural proteins are also identified. Ubiquitous rudiviral proteins with assigned functions include glycosyl transferases and a S-adenosylmethionine-dependent methyltransferase, as well as a Holliday junction resolvase, a transcriptionally coupled helicase and nuclease implicated in DNA replication. Analysis of matches between known crenarchaeal chromosomal CRISPR spacer sequences, implicated in a viral defense system, and rudiviral genomes revealed that about 10% of the 3,042 unique acidothermophile spacers yield significant matches to rudiviral genomes, with a bias to highly conserved protein genes, consistent with the widespread presence of rudiviruses in hot acidophilic environments. We propose that the 12-bp indels which are commonly found in conserved rudiviral protein genes may be generated as a reaction to the presence of the host CRISPR defense system.
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35
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Abstract
Thermophilic viruses were reported decades ago; however, knowledge of their diversity, biology, and ecological impact is limited. Previous research on thermophilic viruses focused on cultivated strains. This study examined metagenomic profiles of viruses directly isolated from two mildly alkaline hot springs, Bear Paw (74 degrees C) and Octopus (93 degrees C). Using a new method for constructing libraries from picograms of DNA, nearly 30 Mb of viral DNA sequence was determined. In contrast to previous studies, sequences were assembled at 50% and 95% identity, creating composite contigs up to 35 kb and facilitating analysis of the inherent heterogeneity in the populations. Lowering the assembly identity reduced the estimated number of viral types from 1,440 and 1,310 to 548 and 283, respectively. Surprisingly, the diversity of viral species in these springs approaches that in moderate-temperature environments. While most known thermophilic viruses have a chronic, nonlytic infection lifestyle, analysis of coding sequences suggests lytic viruses are more common in geothermal environments than previously thought. The 50% assembly included one contig with high similarity and perfect synteny to nine genes from Pyrobaculum spherical virus (PSV). In fact, nearly all the genes of the 28-kb genome of PSV have apparent homologs in the metagenomes. Similarities to thermoacidophilic viruses isolated on other continents were limited to specific open reading frames but were equally strong. Nearly 25% of the reads showed significant similarity between the hot springs, suggesting a common subterranean source. To our knowledge, this is the first application of metagenomics to viruses of geothermal origin.
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36
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Krupovic M, Bamford DH. Archaeal proviruses TKV4 and MVV extend the PRD1-adenovirus lineage to the phylum Euryarchaeota. Virology 2008; 375:292-300. [PMID: 18308362 DOI: 10.1016/j.virol.2008.01.043] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Revised: 01/28/2008] [Accepted: 01/30/2008] [Indexed: 10/22/2022]
Abstract
The viral lineage hypothesis predicting a common origin for viruses that infect hosts residing in different domains of life gains more support as data on viral structures accumulates. One such lineage is the PRD1-adenovirus lineage, which unites icosahedral dsDNA viruses with large facets and a double beta-barrel trimer coat protein. This lineage is represented by a number of viruses infecting bacteria and eukaryotes. However, only one member of the lineage, Sulfolobus turreted icosahedral virus, infecting a crenarchaeal host, has been identified in the domain Archaea. In this study we characterize the genomic sequences of two archaeal proviruses, TKV4 and MVV, integrated into the 5'- and 3'-distal regions of tRNA genes of the euryarchaeal species Thermococcus kodakaraensis KOD1 and Methanococcus voltae A3, respectively. Bioinformatic approaches allowed placement of TKV4 and MVV into the PRD1-adenovirus lineage, thus extending the lineage to the second archaeal phylum, Euryarchaeota.
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Affiliation(s)
- Mart Krupovic
- Department of Biological and Environmental Sciences, Biocenter 2, P.O. Box 56 (Viikinkaari 5), FIN-00014 University of Helsinki, Finland.
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37
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Structure of the acidianus filamentous virus 3 and comparative genomics of related archaeal lipothrixviruses. J Virol 2007; 82:371-81. [PMID: 17942536 DOI: 10.1128/jvi.01410-07] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Four novel filamentous viruses with double-stranded DNA genomes, namely, Acidianus filamentous virus 3 (AFV3), AFV6, AFV7, and AFV8, have been characterized from the hyperthermophilic archaeal genus Acidianus, and they are assigned to the Betalipothrixvirus genus of the family Lipothrixviridae. The structures of the approximately 2-mum-long virions are similar, and one of them, AFV3, was studied in detail. It consists of a cylindrical envelope containing globular subunits arranged in a helical formation that is unique for any known double-stranded DNA virus. The envelope is 3.1 nm thick and encases an inner core with two parallel rows of protein subunits arranged like a zipper. Each end of the virion is tapered and carries three short filaments. Two major structural proteins were identified as being common to all betalipothrixviruses. The viral genomes were sequenced and analyzed, and they reveal a high level of conservation in both gene content and gene order over large regions, with this similarity extending partly to the earlier described betalipothrixvirus Sulfolobus islandicus filamentous virus. A few predicted gene products of each virus, in addition to the structural proteins, could be assigned specific functions, including a putative helicase involved in Holliday junction branch migration, a nuclease, a protein phosphatase, transcriptional regulators, and glycosyltransferases. The AFV7 genome appears to have undergone intergenomic recombination with a large section of an AFV2-like viral genome, apparently resulting in phenotypic changes, as revealed by the presence of AFV2-like termini in the AFV7 virions. Shared features of the genomes include (i) large inverted terminal repeats exhibiting conserved, regularly spaced direct repeats; (ii) a highly conserved operon encoding the two major structural proteins; (iii) multiple overlapping open reading frames, which may be indicative of gene recoding; (iv) putative 12-bp genetic elements; and (v) partial gene sequences corresponding closely to spacer sequences of chromosomal repeat clusters.
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38
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Ackermann HW, Kropinski AM. Curated list of prokaryote viruses with fully sequenced genomes. Res Microbiol 2007; 158:555-66. [PMID: 17889511 DOI: 10.1016/j.resmic.2007.07.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2007] [Revised: 07/18/2007] [Accepted: 07/18/2007] [Indexed: 11/19/2022]
Abstract
Genome sequencing is of enormous importance for classification of prokaryote viruses and for understanding the evolution of these viruses. This survey covers 284 sequenced viruses for which a full description has been published and for which the morphology is known. This corresponds to 219 (4%) of tailed and 75 (36%) of tailless viruses of prokaryotes. The number of sequenced tailless viruses almost doubles if viruses of unknown morphology are counted. The sequences are from representatives of 15 virus families and three groups without family status, including eight taxa of archaeal viruses. Tailed phages, especially those with large genomes and hosts other than enterobacteria or lactococci, mycobacteria and pseudomonads, are vastly under investigated.
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Affiliation(s)
- Hans-W Ackermann
- Felix d'Herelle Reference Center for Bacterial Viruses, Department of Medical Biology, Faculty of Medicine, Laval University, Québec, QC G1K 7P4, Canada.
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Geslin C, Gaillard M, Flament D, Rouault K, Le Romancer M, Prieur D, Erauso G. Analysis of the first genome of a hyperthermophilic marine virus-like particle, PAV1, isolated from Pyrococcus abyssi. J Bacteriol 2007; 189:4510-9. [PMID: 17449623 PMCID: PMC1913373 DOI: 10.1128/jb.01896-06] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Only one virus-like particle (VLP) has been reported from hyperthermophilic Euryarchaeotes. This VLP, named PAV1, is shaped like a lemon and was isolated from a strain of "Pyrococcus abyssi," a deep-sea isolate. Its genome consists of a double-stranded circular DNA of 18 kb which is also present at a high copy number (60 per chromosome) free within the host cytoplasm but is not integrated into the host chromosome. Here, we report the results of complete analysis of the PAV1 genome. All the 25 predicted genes, except 3, are located on one DNA strand. A transcription map has been made by using a reverse transcription-PCR assay. All the identified open reading frames (ORFs) are transcribed. The most significant similarities relate to four ORFs. ORF 180a shows 31% identity with ORF 181 of the pRT1 plasmid isolated from Pyrococcus sp. strain JT1. ORFs 676 and 678 present similarities with a concanavalin A-like lectin/glucanase domain, which could be involved in the process of host-virus recognition, and ORF 59 presents similarities with the transcriptional regulator CopG. The genome of PAV1 displays unique features at the nucleic and proteinic level, indicating that PAV1 should be attached at least to a novel genus or virus family.
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Affiliation(s)
- C Geslin
- Laboratoire de Microbiologie des Environnements Extrêmes, UMR 6197 (CNRS, UBO, IFREMER), Place Nicolas Copernic, Technopôle Brest-Iroise, 29280 Plouzané, France.
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Larson ET, Eilers BJ, Reiter D, Ortmann AC, Young MJ, Lawrence CM. A new DNA binding protein highly conserved in diverse crenarchaeal viruses. Virology 2007; 363:387-96. [PMID: 17336360 DOI: 10.1016/j.virol.2007.01.027] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2006] [Revised: 12/26/2006] [Accepted: 01/18/2007] [Indexed: 11/16/2022]
Abstract
Sulfolobus turreted icosahedral virus (STIV) infects Sulfolobus species found in the hot springs of Yellowstone National Park. Its 37 open reading frames (ORFs) generally lack sequence similarity to other genes. One exception, however, is ORF B116. While its function is unknown, orthologs are found in three additional crenarchaeal viral families. Due to the central importance of this protein family to crenarchaeal viruses, we have undertaken structural and biochemical studies of B116. The structure reveals a previously unobserved fold consisting of a five-stranded beta-sheet flanked on one side by three alpha helices. Two subunits come together to form a homodimer with a 10-stranded mixed beta-sheet, where the topology of the central strands resembles an unclosed beta-barrel. Highly conserved loops rise above the surface of the saddle-shaped protein and suggest an interaction with the major groove of DNA. The predicted B116-DNA interaction is confirmed by electrophoretic mobility shift assays.
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Affiliation(s)
- Eric T Larson
- Thermal Biology Institute, Montana State University, Bozeman, MT 59717, USA
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41
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Abstract
DNA viruses of the Archaea have highly diverse and often exceptionally complex morphotypes. Many have been isolated from geothermally heated hot environments, raising intriguing questions about their origins, and contradicting the widespread notion of limited biodiversity in extreme environments. Here, we provide a unifying view on archaeal viruses, and present them as a particular assemblage that is fundamentally different in morphotype and genome from the DNA viruses of the other two domains of life, the Bacteria and Eukarya.
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Affiliation(s)
- David Prangishvili
- Molecular Biology of the Gene in Extremophiles Unit, Institut Pasteur, rue du Docteur Roux 25, F-75724 Paris Cedex 15, France
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42
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Larson ET, Reiter D, Young M, Lawrence CM. Structure of A197 from Sulfolobus turreted icosahedral virus: a crenarchaeal viral glycosyltransferase exhibiting the GT-A fold. J Virol 2006; 80:7636-44. [PMID: 16840342 PMCID: PMC1563732 DOI: 10.1128/jvi.00567-06] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sulfolobus turreted icosahedral virus (STIV) was the first icosahedral virus characterized from an archaeal host. It infects Sulfolobus species that thrive in the acidic hot springs (pH 2.9 to 3.9 and 72 to 92 degrees C) of Yellowstone National Park. The overall capsid architecture and the structure of its major capsid protein are very similar to those of the bacteriophage PRD1 and eukaryotic viruses Paramecium bursaria Chlorella virus 1 and adenovirus, suggesting a viral lineage that predates the three domains of life. The 17,663-base-pair, circular, double-stranded DNA genome contains 36 potential open reading frames, whose sequences generally show little similarity to other genes in the sequence databases. However, functional and evolutionary information may be suggested by a protein's three-dimensional structure. To this end, we have undertaken structural studies of the STIV proteome. Here we report our work on A197, the product of an STIV open reading frame. The structure of A197 reveals a GT-A fold that is common to many members of the glycosyltransferase superfamily. A197 possesses a canonical DXD motif and a putative catalytic base that are hallmarks of this family of enzymes, strongly suggesting a glycosyltransferase activity for A197. Potential roles for the putative glycosyltransferase activity of A197 and their evolutionary implications are discussed.
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Affiliation(s)
- Eric T Larson
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59715, USA
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43
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Ahn DG, Kim SI, Rhee JK, Kim KP, Pan JG, Oh JW. TTSV1, a new virus-like particle isolated from the hyperthermophilic crenarchaeote Thermoproteus tenax. Virology 2006; 351:280-90. [PMID: 16682063 DOI: 10.1016/j.virol.2006.03.039] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2005] [Revised: 12/30/2005] [Accepted: 03/28/2006] [Indexed: 11/23/2022]
Abstract
A new virus-like particle TTSV1 was isolated from the hyperthermophilic crenarchaeote Thermoproteus tenax sampled at a hot spring region in Indonesia. TTSV1 had a spherical shape with a diameter of approximately 70 nm and was morphologically similar to the PSV isolated from a strain of Pyrobaculum. The 21.6 kb linear double-stranded DNA genome of TTSV1 had 38 open reading frames (ORFs), of which 15 ORFs were most similar to those of PSV. The remaining 23 ORFs showed little similarity to proteins in the public databases. Southern blot analysis demonstrated that the viral genome is not integrated into the host chromosome. TTSV1 consisted of three putative structural proteins of 10, 20, and 35 kDa in size, and the 10-kDa major protein was identified by mass spectrometry as a TTSV1 gene product. TTSV1 could be assigned as a new member of the newly emerged Globuloviridae family that includes so far only one recently characterized virus PSV.
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Affiliation(s)
- Dae-Gyun Ahn
- Department of Biotechnology, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-749, Korea
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44
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Ortmann AC, Wiedenheft B, Douglas T, Young M. Hot crenarchaeal viruses reveal deep evolutionary connections. Nat Rev Microbiol 2006; 4:520-8. [PMID: 16755285 DOI: 10.1038/nrmicro1444] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The discovery of archaeal viruses provides insights into the fundamental biochemistry and evolution of the Archaea. Recent studies have identified a wide diversity of archaeal viruses within the hot springs of Yellowstone National Park and other high-temperature environments worldwide. These viruses are often morphologically unique and code for genes with little similarity to other known genes in the biosphere, a characteristic that has complicated efforts to trace their evolutionary history. Comparative genomics combined with structural analysis indicate that spindle-shaped virus lineages might be unique to the Archaea, whereas other icosahedral viruses might share a common lineage with viruses of Bacteria and Eukarya. These studies provide insights into the evolutionary history of viruses in all three domains of life.
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Affiliation(s)
- Alice C Ortmann
- Thermal Biology Institute, Montana State University, Bozeman, Montana 59717, USA
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45
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Prangishvili D, Garrett RA, Koonin EV. Evolutionary genomics of archaeal viruses: unique viral genomes in the third domain of life. Virus Res 2006; 117:52-67. [PMID: 16503363 DOI: 10.1016/j.virusres.2006.01.007] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2005] [Revised: 01/05/2006] [Accepted: 01/09/2006] [Indexed: 10/25/2022]
Abstract
In terms of virion morphology, the known viruses of archaea fall into two distinct classes: viruses of mesophilic and moderately thermophilic Eueryarchaeota closely resemble head-and-tail bacteriophages whereas viruses of hyperthermophilic Crenarchaeota show a variety of unique morphotypes. In accord with this distinction, the sequenced genomes of euryarchaeal viruses encode many proteins homologous to bacteriophage capsid proteins. In contrast, initial analysis of the crenarchaeal viral genomes revealed no relationships with bacteriophages and, generally, very few proteins with detectable homologs. Here we describe a re-analysis of the proteins encoded by archaeal viruses, with an emphasis on comparative genomics of the unique viruses of Crenarchaeota. Detailed examination of conserved domains and motifs uncovered a significant number of previously unnoticed homologous relationships among the proteins of crenarchaeal viruses and between viral proteins and those from cellular life forms and allowed functional predictions for some of these conserved genes. A small pool of genes is shared by overlapping subsets of crenarchaeal viruses, in a general analogy with the metagenome structure of bacteriophages. The proteins encoded by the genes belonging to this pool include predicted transcription regulators, ATPases implicated in viral DNA replication and packaging, enzymes of DNA precursor metabolism, RNA modification enzymes, and glycosylases. In addition, each of the crenarchaeal viruses encodes several proteins with prokaryotic but not viral homologs, some of which, predictably, seem to have been scavenged from the crenarchaeal hosts, but others might have been acquired from bacteria. We conclude that crenarchaeal viruses are, in general, evolutionarily unrelated to other known viruses and, probably, evolved via independent accretion of genes derived from the hosts and, through more complex routes of horizontal gene transfer, from other prokaryotes.
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Affiliation(s)
- David Prangishvili
- Unité de Biologie Moléculaire du Gène chez les Extrêmophiles, Institut Pasteur, rue Dr. Roux 25, 75724 Paris Cedex 15, France
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Prangishvili D, Garrett RA. Viruses of hyperthermophilic Crenarchaea. Trends Microbiol 2005; 13:535-42. [PMID: 16154357 DOI: 10.1016/j.tim.2005.08.013] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2005] [Revised: 07/14/2005] [Accepted: 08/31/2005] [Indexed: 10/25/2022]
Abstract
Since the discovery of the Archaea--the third domain of life--by Woese and colleagues in 1977, the subsequent developments in molecular and cell biology, and also genomics, have strongly reinforced the view that archaea and eukarya co-evolved, separately from bacteria, over a long time. However, when one examines the archaeal viruses, the picture appears complex. Most viruses that are known to infect members of the kingdom Euryarchaeota resemble bacterial viruses, whereas those associated with the kingdom Crenarchaeota show little resemblance to either bacterial or eukaryal viruses. This review summarizes our current knowledge of this group of exceptional and highly diverse archaeal viruses.
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Affiliation(s)
- David Prangishvili
- Molecular Biology of the Gene in Extremophiles Unit, Institut Pasteur, rue Dr. Roux 25, 75724 Paris Cedex 15, France
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Häring M, Rachel R, Peng X, Garrett RA, Prangishvili D. Viral diversity in hot springs of Pozzuoli, Italy, and characterization of a unique archaeal virus, Acidianus bottle-shaped virus, from a new family, the Ampullaviridae. J Virol 2005; 79:9904-11. [PMID: 16014951 PMCID: PMC1181580 DOI: 10.1128/jvi.79.15.9904-9911.2005] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Virus-like particles with five different morphotypes were observed in an enriched environmental sample from a hot, acidic spring (87 to 93 degrees C, pH 1.5) in Pozzuoli, Italy. The morphotypes included rigid rods, flexible filaments, and novel, exceptional forms. Particles of each type were isolated, and they were shown to represent viable virions of five novel viruses which infect members of the hyperthermophilic archaeal genus Acidianus. One of these, named the Acidianus bottle-shaped virus, ABV, exhibits a previously unreported morphotype. The bottle-shaped virion carries an envelope which encases a funnel-shaped core. The pointed end of the virion is likely to be involved in adsorption and channeling of viral DNA into host cells. The broad end exhibits 20 (+/- 2) thin filaments which appear to be inserted into a disk, or ring, and are interconnected at their bases. These filaments are apparently not involved in adsorption. ABV virions contain six proteins in the size range 15 to 80 kDa and a 23.9-kb linear, double-stranded DNA genome. Virus replication does not cause lysis of host cells. On the basis of its unique morphotype and structure, we propose to assign ABV to a new viral family, the Ampullaviridae.
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Affiliation(s)
- Monika Häring
- Molecular Biology of the Gene in Extremophiles Unit, Institut Pasteur, Paris, France
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