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Bhoobalan-Chitty Y, Xu S, Martinez-Alvarez L, Karamycheva S, Makarova KS, Koonin EV, Peng X. Regulatory sequence-based discovery of anti-defense genes in archaeal viruses. Nat Commun 2024; 15:3699. [PMID: 38698035 PMCID: PMC11065993 DOI: 10.1038/s41467-024-48074-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 04/19/2024] [Indexed: 05/05/2024] Open
Abstract
In silico identification of viral anti-CRISPR proteins (Acrs) has relied largely on the guilt-by-association method using known Acrs or anti-CRISPR associated proteins (Acas) as the bait. However, the low number and limited spread of the characterized archaeal Acrs and Aca hinders our ability to identify Acrs using guilt-by-association. Here, based on the observation that the few characterized archaeal Acrs and Aca are transcribed immediately post viral infection, we hypothesize that these genes, and many other unidentified anti-defense genes (ADG), are under the control of conserved regulatory sequences including a strong promoter, which can be used to predict anti-defense genes in archaeal viruses. Using this consensus sequence based method, we identify 354 potential ADGs in 57 archaeal viruses and 6 metagenome-assembled genomes. Experimental validation identified a CRISPR subtype I-A inhibitor and the first virally encoded inhibitor of an archaeal toxin-antitoxin based immune system. We also identify regulatory proteins potentially akin to Acas that can facilitate further identification of ADGs combined with the guilt-by-association approach. These results demonstrate the potential of regulatory sequence analysis for extensive identification of ADGs in viruses of archaea and bacteria.
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Affiliation(s)
| | - Shuanshuan Xu
- Department of Biology, University of Copenhagen, Copenhagen N, Denmark
| | | | - Svetlana Karamycheva
- National Center for Biotechnology Information, National Library of Medicine, NIH, Bethesda, MD, USA
| | - Kira S Makarova
- National Center for Biotechnology Information, National Library of Medicine, NIH, Bethesda, MD, USA
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, NIH, Bethesda, MD, USA
| | - Xu Peng
- Department of Biology, University of Copenhagen, Copenhagen N, Denmark.
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2
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Duan C, Liu Y, Liu Y, Liu L, Cai M, Zhang R, Zeng Q, Koonin EV, Krupovic M, Li M. Diversity of Bathyarchaeia viruses in metagenomes and virus-encoded CRISPR system components. ISME COMMUNICATIONS 2024; 4:ycad011. [PMID: 38328448 PMCID: PMC10848311 DOI: 10.1093/ismeco/ycad011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 12/14/2023] [Accepted: 12/18/2023] [Indexed: 02/09/2024]
Abstract
Bathyarchaeia represent a class of archaea common and abundant in sedimentary ecosystems. Here we report 56 metagenome-assembled genomes of Bathyarchaeia viruses identified in metagenomes from different environments. Gene sharing network and phylogenomic analyses led to the proposal of four virus families, including viruses of the realms Duplodnaviria and Adnaviria, and archaea-specific spindle-shaped viruses. Genomic analyses uncovered diverse CRISPR elements in these viruses. Viruses of the proposed family "Fuxiviridae" harbor an atypical Type IV-B CRISPR-Cas system and a Cas4 protein that might interfere with host immunity. Viruses of the family "Chiyouviridae" encode a Cas2-like endonuclease and two mini-CRISPR arrays, one with a repeat identical to that in the host CRISPR array, potentially allowing the virus to recruit the host CRISPR adaptation machinery to acquire spacers that could contribute to competition with other mobile genetic elements or to inhibit host defenses. These findings present an outline of the Bathyarchaeia virome and offer a glimpse into their counter-defense mechanisms.
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Affiliation(s)
- Changhai Duan
- SZU-HKUST Joint PhD Program in Marine Environmental Science, Shenzhen University, Shenzhen 518060, China
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
- Department of Ocean Science, The Hong Kong University of Science and Technology, Hong Kong 999077, China
| | - Yang Liu
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
| | - Ying Liu
- Institut Pasteur, Université Paris Cité, Archaeal Virology Unit, Paris 75015, France
| | - Lirui Liu
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
| | - Mingwei Cai
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
| | - Rui Zhang
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
| | - Qinglu Zeng
- Department of Ocean Science, The Hong Kong University of Science and Technology, Hong Kong 999077, China
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Mart Krupovic
- Institut Pasteur, Université Paris Cité, Archaeal Virology Unit, Paris 75015, France
| | - Meng Li
- SZU-HKUST Joint PhD Program in Marine Environmental Science, Shenzhen University, Shenzhen 518060, China
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
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3
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Duan C, Liu Y, Liu Y, Liu L, Cai M, Zhang R, Zeng Q, Koonin EV, Krupovic M, Li M. Diversity of Bathyarchaeia viruses in metagenomes and virus-encoded CRISPR system components. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.24.554615. [PMID: 37781628 PMCID: PMC10541130 DOI: 10.1101/2023.08.24.554615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
Bathyarchaeia represent a class of archaea common and abundant in sedimentary ecosystems. The virome of Bathyarchaeia so far has not been characterized. Here we report 56 metagenome-assembled genomes of Bathyarchaeia viruses identified in metagenomes from different environments. Gene sharing network and phylogenomic analyses led to the proposal of four virus families, including viruses of the realms Duplodnaviria and Adnaviria, and archaea-specific spindle-shaped viruses. Genomic analyses uncovered diverse CRISPR elements in these viruses. Viruses of the proposed family 'Fuxiviridae' harbor an atypical type IV-B CRISPR-Cas system and a Cas4 protein that might interfere with host immunity. Viruses of the family 'Chiyouviridae' encode a Cas2-like endonuclease and two mini-CRISPR arrays, one with a repeat identical to that in the host CRISPR array, potentially allowing the virus to recruit the host CRISPR adaptation machinery to acquire spacers that could contribute to competition with other mobile genetic elements or to inhibition of host defenses. These findings present an outline of the Bathyarchaeia virome and offer a glimpse into their counter-defense mechanisms.
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Affiliation(s)
- Changhai Duan
- SZU-HKUST Joint PhD Program in Marine Environmental Science, Shenzhen University, 518060 Shenzhen, China
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, 518060 Shenzhen, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, 518060 Shenzhen, China
- Department of Ocean Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Yang Liu
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, 518060 Shenzhen, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, 518060 Shenzhen, China
| | - Ying Liu
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Archaeal Virology Unit, 75015 Paris, France
| | - Lirui Liu
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, 518060 Shenzhen, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, 518060 Shenzhen, China
| | - Mingwei Cai
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, 518060 Shenzhen, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, 518060 Shenzhen, China
| | - Rui Zhang
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, 518060 Shenzhen, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, 518060 Shenzhen, China
| | - Qinglu Zeng
- Department of Ocean Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
| | - Mart Krupovic
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Archaeal Virology Unit, 75015 Paris, France
| | - Meng Li
- SZU-HKUST Joint PhD Program in Marine Environmental Science, Shenzhen University, 518060 Shenzhen, China
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, 518060 Shenzhen, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, 518060 Shenzhen, China
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4
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Lewis AM, Recalde A, Bräsen C, Counts JA, Nussbaum P, Bost J, Schocke L, Shen L, Willard DJ, Quax TEF, Peeters E, Siebers B, Albers SV, Kelly RM. The biology of thermoacidophilic archaea from the order Sulfolobales. FEMS Microbiol Rev 2021; 45:fuaa063. [PMID: 33476388 PMCID: PMC8557808 DOI: 10.1093/femsre/fuaa063] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 11/26/2020] [Indexed: 12/13/2022] Open
Abstract
Thermoacidophilic archaea belonging to the order Sulfolobales thrive in extreme biotopes, such as sulfuric hot springs and ore deposits. These microorganisms have been model systems for understanding life in extreme environments, as well as for probing the evolution of both molecular genetic processes and central metabolic pathways. Thermoacidophiles, such as the Sulfolobales, use typical microbial responses to persist in hot acid (e.g. motility, stress response, biofilm formation), albeit with some unusual twists. They also exhibit unique physiological features, including iron and sulfur chemolithoautotrophy, that differentiate them from much of the microbial world. Although first discovered >50 years ago, it was not until recently that genome sequence data and facile genetic tools have been developed for species in the Sulfolobales. These advances have not only opened up ways to further probe novel features of these microbes but also paved the way for their potential biotechnological applications. Discussed here are the nuances of the thermoacidophilic lifestyle of the Sulfolobales, including their evolutionary placement, cell biology, survival strategies, genetic tools, metabolic processes and physiological attributes together with how these characteristics make thermoacidophiles ideal platforms for specialized industrial processes.
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Affiliation(s)
- April M Lewis
- Department of Chemical and Biomolecular Engineering, North Carolina State University. Raleigh, NC 27695, USA
| | - Alejandra Recalde
- Institute for Biology, Molecular Biology of Archaea, University of Freiburg, 79104 Freiburg, Germany
| | - Christopher Bräsen
- Department of Molecular Enzyme Technology and Biochemistry, Environmental Microbiology and Biotechnology, and Centre for Water and Environmental Research, University of Duisburg-Essen, 45117 Essen, Germany
| | - James A Counts
- Department of Chemical and Biomolecular Engineering, North Carolina State University. Raleigh, NC 27695, USA
| | - Phillip Nussbaum
- Institute for Biology, Molecular Biology of Archaea, University of Freiburg, 79104 Freiburg, Germany
| | - Jan Bost
- Institute for Biology, Molecular Biology of Archaea, University of Freiburg, 79104 Freiburg, Germany
| | - Larissa Schocke
- Department of Molecular Enzyme Technology and Biochemistry, Environmental Microbiology and Biotechnology, and Centre for Water and Environmental Research, University of Duisburg-Essen, 45117 Essen, Germany
| | - Lu Shen
- Department of Molecular Enzyme Technology and Biochemistry, Environmental Microbiology and Biotechnology, and Centre for Water and Environmental Research, University of Duisburg-Essen, 45117 Essen, Germany
| | - Daniel J Willard
- Department of Chemical and Biomolecular Engineering, North Carolina State University. Raleigh, NC 27695, USA
| | - Tessa E F Quax
- Archaeal Virus–Host Interactions, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Eveline Peeters
- Research Group of Microbiology, Department of Bioengineering Sciences, Vrije Universiteit Brussel, 1050 Brussels, Belgium
| | - Bettina Siebers
- Department of Molecular Enzyme Technology and Biochemistry, Environmental Microbiology and Biotechnology, and Centre for Water and Environmental Research, University of Duisburg-Essen, 45117 Essen, Germany
| | - Sonja-Verena Albers
- Institute for Biology, Molecular Biology of Archaea, University of Freiburg, 79104 Freiburg, Germany
| | - Robert M Kelly
- Department of Chemical and Biomolecular Engineering, North Carolina State University. Raleigh, NC 27695, USA
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5
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Adnaviria: a New Realm for Archaeal Filamentous Viruses with Linear A-Form Double-Stranded DNA Genomes. J Virol 2021; 95:e0067321. [PMID: 34011550 DOI: 10.1128/jvi.00673-21] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The International Committee on Taxonomy of Viruses (ICTV) has recently adopted a comprehensive, hierarchical system of virus taxa. The highest ranks in this hierarchy are realms, each of which is considered monophyletic but apparently originated independently of other realms. Here, we announce the creation of a new realm, Adnaviria, which unifies archaeal filamentous viruses with linear A-form double-stranded DNA genomes and characteristic major capsid proteins unrelated to those encoded by other known viruses.
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6
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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: 23] [Impact Index Per Article: 5.8] [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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7
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Multiple origins of prokaryotic and eukaryotic single-stranded DNA viruses from bacterial and archaeal plasmids. Nat Commun 2019; 10:3425. [PMID: 31366885 PMCID: PMC6668415 DOI: 10.1038/s41467-019-11433-0] [Citation(s) in RCA: 98] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Accepted: 07/10/2019] [Indexed: 02/07/2023] Open
Abstract
Single-stranded (ss) DNA viruses are a major component of the earth virome. In particular, the circular, Rep-encoding ssDNA (CRESS-DNA) viruses show high diversity and abundance in various habitats. By combining sequence similarity network and phylogenetic analyses of the replication proteins (Rep) belonging to the HUH endonuclease superfamily, we show that the replication machinery of the CRESS-DNA viruses evolved, on three independent occasions, from the Reps of bacterial rolling circle-replicating plasmids. The CRESS-DNA viruses emerged via recombination between such plasmids and cDNA copies of capsid genes of eukaryotic positive-sense RNA viruses. Similarly, the rep genes of prokaryotic DNA viruses appear to have evolved from HUH endonuclease genes of various bacterial and archaeal plasmids. Our findings also suggest that eukaryotic polyomaviruses and papillomaviruses with dsDNA genomes have evolved via parvoviruses from CRESS-DNA viruses. Collectively, our results shed light on the complex evolutionary history of a major class of viruses revealing its polyphyletic origins. Most single-stranded DNA viruses have small genomes replicated by rolling circle mechanism which is initiated by the Rep protein. Here, using sequence similarity network and phylogenetic analyses, Kazlauskas et al. show that viral Reps evolved from Reps of bacterial and archaeal plasmids on multiple independent occasions.
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8
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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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9
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Cas4 Nucleases Can Effect Specific Integration of CRISPR Spacers. J Bacteriol 2019; 201:JB.00747-18. [PMID: 30936372 DOI: 10.1128/jb.00747-18] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Accepted: 03/26/2019] [Indexed: 01/19/2023] Open
Abstract
Clustered regularly interspaced short palindromic repeat (CRISPR)-Cas systems incorporate short DNA fragments from invasive genetic elements into host CRISPR arrays in order to generate host immunity. Recently, we demonstrated that the Csa3a regulator protein triggers CCN protospacer-adjacent motif (PAM)-dependent CRISPR spacer acquisition in the subtype I-A CRISPR-Cas system of Sulfolobus islandicus However, the mechanisms underlying specific protospacer selection and spacer insertion remained unclear. Here, we demonstrate that two Cas4 family proteins (Cas4 and Csa1) have essential roles (i) in recognizing the 5' PAM and 3' nucleotide motif of protospacers and (ii) in determining both the spacer length and its orientation. Furthermore, we identify amino acid residues of the Cas4 proteins that facilitate these functions. Overexpression of the Cas4 and Csa1 proteins, and also that of an archaeal virus-encoded Cas4 protein, resulted in strongly reduced adaptation efficiency, and the former proteins yielded a high incidence of PAM-dependent atypical spacer integration or of PAM-independent spacer integration. We further demonstrated that in plasmid challenge experiments, overexpressed Cas4-mediated defective spacer acquisition in turn potentially enabled targeted DNA to escape subtype I-A CRISPR-Cas interference. In summary, these results define the specific involvement of diverse Cas4 proteins in in vivo CRISPR spacer acquisition. Furthermore, we provide support for an anti-CRISPR role for virus-encoded Cas4 proteins that involves compromising CRISPR-Cas interference activity by hindering spacer acquisition.IMPORTANCE The Cas4 family endonuclease is an essential component of the adaptation module in many variants of CRISPR-Cas adaptive immunity systems. The Crenarchaeota Sulfolobus islandicus REY15A carries two cas4 genes (cas4 and csa1) linked to the CRISPR arrays. Here, we demonstrate that Cas4 and Csa1 are essential to CRISPR spacer acquisition in this organism. Both proteins specify the upstream and downstream conserved nucleotide motifs of the protospacers and define the spacer length and orientation in the acquisition process. Conserved amino acid residues, in addition to those recently reported, were identified to be important for these functions. More importantly, overexpression of the Sulfolobus viral Cas4 abolished spacer acquisition, providing support for an anti-CRISPR role for virus-encoded Cas4 proteins that inhibit spacer acquisition.
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10
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Sharma A, Schmidt M, Kiesel B, Mahato NK, Cralle L, Singh Y, Richnow HH, Gilbert JA, Arnold W, Lal R. Bacterial and Archaeal Viruses of Himalayan Hot Springs at Manikaran Modulate Host Genomes. Front Microbiol 2018; 9:3095. [PMID: 30619174 PMCID: PMC6302217 DOI: 10.3389/fmicb.2018.03095] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 11/29/2018] [Indexed: 11/30/2022] Open
Abstract
Hot spring-associated viruses, particularly the archaeal viruses, remain under-examined compared to bacteriophages. Previous metagenomic studies of the Manikaran hot springs in India suggested an abundance of viral DNA, which prompted us to examine the virus–host (bacterial and archaeal) interactions in sediment and microbial mat samples collected from the thermal discharges. Here, we characterize the viruses (both bacterial and archaeal) from this Himalayan hot spring using both metagenomics assembly and electron microscopy. We utilized four shotgun samples from sediment (78–98°C) and two from microbial mats (50°C) to reconstruct 65 bacteriophage genomes (24–200 kb). We also identified 59 archaeal viruses that were notably abundant across the sediment samples. Whole-genome analyses of the reconstructed bacteriophage genomes revealed greater genomic conservation in sediments (65%) compared to microbial mats (49%). However, a minimal phage genome was still maintained across both sediment and microbial mats suggesting a common origin. To complement the metagenomic data, scanning-electron and helium-ion microscopy were used to reveal diverse morphotypes of Caudovirales and archaeal viruses. The genome level annotations provide further evidence for gene-level exchange between virus and host in these hot springs, and augments our knowledgebase for bacteriophages, archaeal viruses and Clustered Regularly Interspaced Short Palindromic Repeat cassettes, which provide a critical resource for studying viromes in extreme natural environments.
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Affiliation(s)
- Anukriti Sharma
- Department of Zoology, University of Delhi, New Delhi, India.,Biosciences Division, Argonne National Laboratory, Lemont, IL, United States.,Department of Surgery, University of Chicago, Chicago, IL, United States
| | - Matthias Schmidt
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Bärbel Kiesel
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Nitish K Mahato
- Department of Zoology, University of Delhi, New Delhi, India
| | - Lauren Cralle
- Biosciences Division, Argonne National Laboratory, Lemont, IL, United States.,Department of Surgery, University of Chicago, Chicago, IL, United States
| | - Yogendra Singh
- Department of Zoology, University of Delhi, New Delhi, India
| | - Hans H Richnow
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Jack A Gilbert
- Biosciences Division, Argonne National Laboratory, Lemont, IL, United States.,Department of Surgery, University of Chicago, Chicago, IL, United States
| | - Wyatt Arnold
- Department of Surgery, University of Chicago, Chicago, IL, United States
| | - Rup Lal
- Department of Zoology, University of Delhi, New Delhi, India
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11
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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: 138] [Impact Index Per Article: 19.7] [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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12
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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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Peeters E, Boon M, Rollie C, Willaert RG, Voet M, White MF, Prangishvili D, Lavigne R, Quax TEF. DNA-Interacting Characteristics of the Archaeal Rudiviral Protein SIRV2_Gp1. Viruses 2017; 9:v9070190. [PMID: 28718834 PMCID: PMC5537682 DOI: 10.3390/v9070190] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 07/06/2017] [Accepted: 07/10/2017] [Indexed: 12/02/2022] Open
Abstract
Whereas the infection cycles of many bacterial and eukaryotic viruses have been characterized in detail, those of archaeal viruses remain largely unexplored. Recently, studies on a few model archaeal viruses such as SIRV2 (Sulfolobus islandicus rod-shaped virus) have revealed an unusual lysis mechanism that involves the formation of pyramidal egress structures on the host cell surface. To expand understanding of the infection cycle of SIRV2, we aimed to functionally characterize gp1, which is a SIRV2 gene with unknown function. The SIRV2_Gp1 protein is highly expressed during early stages of infection and it is the only protein that is encoded twice on the viral genome. It harbours a helix-turn-helix motif and was therefore hypothesized to bind DNA. The DNA-binding behavior of SIRV2_Gp1 was characterized with electrophoretic mobility shift assays and atomic force microscopy. We provide evidence that the protein interacts with DNA and that it forms large aggregates, thereby causing extreme condensation of the DNA. Furthermore, the N-terminal domain of the protein mediates toxicity to the viral host Sulfolobus. Our findings may lead to biotechnological applications, such as the development of a toxic peptide for the containment of pathogenic bacteria, and add to our understanding of the Rudiviral infection cycle.
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Affiliation(s)
- Eveline Peeters
- Research Group of Microbiology, Department of Bio-Engineering Sciences, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium.
| | - Maarten Boon
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, Kasteelpark Arenberg 21 box 2462, Heverlee, 3001 Leuven, Belgium.
| | - Clare Rollie
- Biomedical Sciences Research Complex, University of St Andrews, Fife, North Haugh, St. Andrews KY16 9AJ, UK.
| | - Ronnie G Willaert
- Alliance Research Group VUB-UGhent NanoMicrobiology, IJRG VUB-EPFL, BioNanotechnology & NanoMedicine, Research Group Structural Biology Brussels, Department of Bio-Engineering Sciences, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium.
| | - Marleen Voet
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, Kasteelpark Arenberg 21 box 2462, Heverlee, 3001 Leuven, Belgium.
| | - Malcolm F White
- Biomedical Sciences Research Complex, University of St Andrews, Fife, North Haugh, St. Andrews KY16 9AJ, UK.
| | | | - Rob Lavigne
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, Kasteelpark Arenberg 21 box 2462, Heverlee, 3001 Leuven, Belgium.
| | - Tessa E F Quax
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, Kasteelpark Arenberg 21 box 2462, Heverlee, 3001 Leuven, Belgium.
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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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A Novel Type of Polyhedral Viruses Infecting Hyperthermophilic Archaea. J Virol 2017; 91:JVI.00589-17. [PMID: 28424284 DOI: 10.1128/jvi.00589-17] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 04/11/2017] [Indexed: 11/20/2022] Open
Abstract
Encapsidation of genetic material into polyhedral particles is one of the most common structural solutions employed by viruses infecting hosts in all three domains of life. Here, we describe a new virus of hyperthermophilic archaea, Sulfolobus polyhedral virus 1 (SPV1), which condenses its circular double-stranded DNA genome in a manner not previously observed for other known viruses. The genome complexed with virion proteins is wound up sinusoidally into a spherical coil which is surrounded by an envelope and further encased by an outer polyhedral capsid apparently composed of the 20-kDa virion protein. Lipids selectively acquired from the pool of host lipids are integral constituents of the virion. None of the major virion proteins of SPV1 show similarity to structural proteins of known viruses. However, minor structural proteins, which are predicted to mediate host recognition, are shared with other hyperthermophilic archaeal viruses infecting members of the order Sulfolobales The SPV1 genome consists of 20,222 bp and contains 45 open reading frames, only one-fifth of which could be functionally annotated.IMPORTANCE Viruses infecting hyperthermophilic archaea display a remarkable morphological diversity, often presenting architectural solutions not employed by known viruses of bacteria and eukaryotes. Here we present the isolation and characterization of Sulfolobus polyhedral virus 1, which condenses its genome into a unique spherical coil. Due to the original genomic and architectural features of SPV1, the virus should be considered a representative of a new viral family, "Portogloboviridae."
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Differentiation and Structure in Sulfolobus islandicus Rod-Shaped Virus Populations. Viruses 2017; 9:v9050120. [PMID: 28534836 PMCID: PMC5454432 DOI: 10.3390/v9050120] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 05/04/2017] [Accepted: 05/10/2017] [Indexed: 11/17/2022] Open
Abstract
In the past decade, molecular surveys of viral diversity have revealed that viruses are the most diverse and abundant biological entities on Earth. In culture, however, most viral isolates that infect microbes are represented by a few variants isolated on type strains, limiting our ability to study how natural variation affects virus-host interactions in the laboratory. We screened a set of 137 hot spring samples for viruses that infect a geographically diverse panel of the hyperthemophilic crenarchaeon Sulfolobus islandicus. We isolated and characterized eight SIRVs (Sulfolobus islandicus rod-shaped viruses) from two different regions within Yellowstone National Park (USA). Comparative genomics revealed that all SIRV sequenced isolates share 30 core genes that represent 50–60% of the genome. The core genome phylogeny, as well as the distribution of variable genes (shared by some but not all SIRVs) and the signatures of host-virus interactions recorded on the CRISPR (clustered regularly interspaced short palindromic repeats) repeat-spacer arrays of S. islandicus hosts, identify different SIRV lineages, each associated with a different geographic location. Moreover, our studies reveal that SIRV core genes do not appear to be under diversifying selection and thus we predict that the abundant and diverse variable genes govern the coevolutionary arms race between SIRVs and their hosts.
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17
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A virus of hyperthermophilic archaea with a unique architecture among DNA viruses. Proc Natl Acad Sci U S A 2016; 113:2478-83. [PMID: 26884161 DOI: 10.1073/pnas.1518929113] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Viruses package their genetic material in diverse ways. Most known strategies include encapsulation of nucleic acids into spherical or filamentous virions with icosahedral or helical symmetry, respectively. Filamentous viruses with dsDNA genomes are currently associated exclusively with Archaea. Here, we describe a filamentous hyperthermophilic archaeal virus, Pyrobaculum filamentous virus 1 (PFV1), with a type of virion organization not previously observed in DNA viruses. The PFV1 virion, 400 ± 20 × 32 ± 3 nm, contains an envelope and an inner core consisting of two structural units: a rod-shaped helical nucleocapsid formed of two 14-kDa major virion proteins and a nucleocapsid-encompassing protein sheath composed of a single major virion protein of 18 kDa. The virion organization of PFV1 is superficially similar to that of negative-sense RNA viruses of the family Filoviridae, including Ebola virus and Marburg virus. The linear dsDNA of PFV1 carries 17,714 bp, including 60-bp-long terminal inverted repeats, and contains 39 predicted ORFs, most of which do not show similarities to sequences in public databases. PFV1 is a lytic virus that completely disrupts the host cell membrane at the end of the infection cycle.
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Acidianus Tailed Spindle Virus: a New Archaeal Large Tailed Spindle Virus Discovered by Culture-Independent Methods. J Virol 2016; 90:3458-68. [PMID: 26763997 DOI: 10.1128/jvi.03098-15] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 01/07/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The field of viral metagenomics has expanded our understanding of viral diversity from all three domains of life (Archaea, Bacteria, and Eukarya). Traditionally, viral metagenomic studies provide information about viral gene content but rarely provide knowledge about virion morphology and/or cellular host identity. Here we describe a new virus, Acidianus tailed spindle virus (ATSV), initially identified by bioinformatic analysis of viral metagenomic data sets from a high-temperature (80°C) acidic (pH 2) hot spring located in Yellowstone National Park, followed by more detailed characterization using only environmental samples without dependency on culturing. Characterization included the identification of the large tailed spindle virion morphology, determination of the complete 70.8-kb circular double-stranded DNA (dsDNA) viral genome content, and identification of its cellular host. Annotation of the ATSV genome revealed a potential three-domain gene product containing an N-terminal leucine-rich repeat domain, followed by a likely posttranslation regulatory region consisting of high serine and threonine content, and a C-terminal ESCRT-III domain, suggesting interplay with the host ESCRT system. The host of ATSV, which is most closely related to Acidianus hospitalis, was determined by a combination of analysis of cellular clustered regularly interspaced short palindromic repeat (CRISPR)/Cas loci and dual viral and cellular fluorescence in situ hybridization (viral FISH) analysis of environmental samples and confirmed by culture-based infection studies. This work provides an expanded pathway for the discovery, isolation, and characterization of new viruses using culture-independent approaches and provides a platform for predicting and confirming virus hosts. IMPORTANCE Virus discovery and characterization have been traditionally accomplished by using culture-based methods. While a valuable approach, it is limited by the availability of culturable hosts. In this research, we report a virus-centered approach to virus discovery and characterization, linking viral metagenomic sequences to a virus particle, its sequenced genome, and its host directly in environmental samples, without using culture-dependent methods. This approach provides a pathway for the discovery, isolation, and characterization of new viruses. While this study used an acidic hot spring environment to characterize a new archaeal virus, Acidianus tailed spindle virus (ATSV), the approach can be generally applied to any environment to expand knowledge of virus diversity in all three domains of life.
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19
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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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Sulfolobus Spindle-Shaped Virus 1 Contains Glycosylated Capsid Proteins, a Cellular Chromatin Protein, and Host-Derived Lipids. J Virol 2015; 89:11681-91. [PMID: 26355093 DOI: 10.1128/jvi.02270-15] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 09/04/2015] [Indexed: 12/31/2022] Open
Abstract
UNLABELLED Geothermal and hypersaline environments are rich in virus-like particles, among which spindle-shaped morphotypes dominate. Currently, viruses with spindle- or lemon-shaped virions are exclusive to Archaea and belong to two distinct viral families. The larger of the two families, the Fuselloviridae, comprises tail-less, spindle-shaped viruses, which infect hosts from phylogenetically distant archaeal lineages. Sulfolobus spindle-shaped virus 1 (SSV1) is the best known member of the family and was one of the first hyperthermophilic archaeal viruses to be isolated. SSV1 is an attractive model for understanding virus-host interactions in Archaea; however, the constituents and architecture of SSV1 particles remain only partially characterized. Here, we have conducted an extensive biochemical characterization of highly purified SSV1 virions and identified four virus-encoded structural proteins, VP1 to VP4, as well as one DNA-binding protein of cellular origin. The virion proteins VP1, VP3, and VP4 undergo posttranslational modification by glycosylation, seemingly at multiple sites. VP1 is also proteolytically processed. In addition to the viral DNA-binding protein VP2, we show that viral particles contain the Sulfolobus solfataricus chromatin protein Sso7d. Finally, we provide evidence indicating that SSV1 virions contain glycerol dibiphytanyl glycerol tetraether (GDGT) lipids, resolving a long-standing debate on the presence of lipids within SSV1 virions. A comparison of the contents of lipids isolated from the virus and its host cell suggests that GDGTs are acquired by the virus in a selective manner from the host cytoplasmic membrane, likely during progeny egress. IMPORTANCE Although spindle-shaped viruses represent one of the most prominent viral groups in Archaea, structural data on their virion constituents and architecture still are scarce. The comprehensive biochemical characterization of the hyperthermophilic virus SSV1 presented here brings novel and significant insights into the organization and architecture of spindle-shaped virions. The obtained data permit the comparison between spindle-shaped viruses residing in widely different ecological niches, improving our understanding of the adaptation of viruses with unusual morphotypes to extreme environmental conditions.
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21
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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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22
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Quemin ERJ, Quax TEF. Archaeal viruses at the cell envelope: entry and egress. Front Microbiol 2015; 6:552. [PMID: 26097469 PMCID: PMC4456609 DOI: 10.3389/fmicb.2015.00552] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 05/19/2015] [Indexed: 11/13/2022] Open
Abstract
The cell envelope represents the main line of host defense that viruses encounter on their way from one cell to another. The cytoplasmic membrane in general is a physical barrier that needs to be crossed both upon viral entry and exit. Therefore, viruses from the three domains of life employ a wide range of strategies for perforation of the cell membrane, each adapted to the cell surface environment of their host. Here, we review recent insights on entry and egress mechanisms of viruses infecting archaea. Due to the unique nature of the archaeal cell envelope, these particular viruses exhibit novel and unexpected mechanisms to traverse the cellular membrane.
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Affiliation(s)
| | - Tessa E F Quax
- Molecular Biology of Archaea, Institute for Biology II - Microbiology, University of Freiburg , Freiburg, Germany
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23
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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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Makarova KS, Wolf YI, Forterre P, Prangishvili D, Krupovic M, Koonin EV. Dark matter in archaeal genomes: a rich source of novel mobile elements, defense systems and secretory complexes. Extremophiles 2014; 18:877-93. [PMID: 25113822 PMCID: PMC4158269 DOI: 10.1007/s00792-014-0672-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 07/06/2014] [Indexed: 01/29/2023]
Abstract
Microbial genomes encompass a sizable fraction of poorly characterized, narrowly spread fast-evolving genes. Using sensitive methods for sequences comparison and protein structure prediction, we performed a detailed comparative analysis of clusters of such genes, which we denote "dark matter islands", in archaeal genomes. The dark matter islands comprise up to 20% of archaeal genomes and show remarkable heterogeneity and diversity. Nevertheless, three classes of entities are common in these genomic loci: (a) integrated viral genomes and other mobile elements; (b) defense systems, and (c) secretory and other membrane-associated systems. The dark matter islands in the genome of thermophiles and mesophiles show similar general trends of gene content, but thermophiles are substantially enriched in predicted membrane proteins whereas mesophiles have a greater proportion of recognizable mobile elements. Based on this analysis, we predict the existence of several novel groups of viruses and mobile elements, previously unnoticed variants of CRISPR-Cas immune systems, and new secretory systems that might be involved in stress response, intermicrobial conflicts and biogenesis of novel, uncharacterized membrane structures.
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Affiliation(s)
- Kira S Makarova
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD, 20894, USA
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25
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Quemin ERJ, Prangishvili D, Krupovic M. Hard out there: understanding archaeal virus biology. Future Virol 2014. [DOI: 10.2217/fvl.14.52] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Emmanuelle RJ Quemin
- Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Département de Microbiologie, 75015 Paris, France
| | - David Prangishvili
- Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Département de Microbiologie, 75015 Paris, France
| | - Mart Krupovic
- Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Département de Microbiologie, 75015 Paris, France
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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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27
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Protein-protein interactions leading to recruitment of the host DNA sliding clamp by the hyperthermophilic Sulfolobus islandicus rod-shaped virus 2. J Virol 2014; 88:7105-8. [PMID: 24696494 DOI: 10.1128/jvi.00636-14] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Viruses infecting hyperthermophilic archaea typically do not encode DNA polymerases, raising questions regarding their genome replication. Here, using a yeast two-hybrid approach, we have assessed interactions between proteins of Sulfolobus islandicus rod-shaped virus 2 (SIRV2) and the host-encoded proliferating cell nuclear antigen (PCNA), a key DNA replication protein in archaea. Five SIRV2 proteins were found to interact with PCNA, providing insights into the recruitment of host replisome for viral DNA replication.
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28
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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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29
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Abstract
A decisive step in a virus infection cycle is the recognition of a specific receptor present on the host cell surface, subsequently leading to the delivery of the viral genome into the cell interior. Until now, the early stages of infection have not been thoroughly investigated for any virus infecting hyperthermophilic archaea. Here, we present the first study focusing on the primary interactions between the archaeal rod-shaped virus Sulfolobus islandicus rod-shaped virus 2 (SIRV2) (family Rudiviridae) and its hyperthermoacidophilic host, S. islandicus. We show that SIRV2 adsorption is very rapid, with the majority of virions being irreversibly bound to the host cell within 1 min. We utilized transmission electron microscopy and whole-cell electron cryotomography to demonstrate that SIRV2 virions specifically recognize the tips of pilus-like filaments, which are highly abundant on the host cell surface. Following the initial binding, the viral particles are found attached to the sides of the filaments, suggesting a movement along these appendages toward the cell surface. Finally, we also show that SIRV2 establishes superinfection exclusion, a phenomenon not previously described for archaeal viruses.
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30
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Abstract
Archaeal viruses display unusually high genetic and morphological diversity. Studies of these viruses proved to be instrumental for the expansion of knowledge on viral diversity and evolution. The Sulfolobus islandicus rod-shaped virus 2 (SIRV2) is a model to study virus-host interactions in Archaea. It is a lytic virus that exploits a unique egress mechanism based on the formation of remarkable pyramidal structures on the host cell envelope. Using whole-transcriptome sequencing, we present here a global map defining host and viral gene expression during the infection cycle of SIRV2 in its hyperthermophilic host S. islandicus LAL14/1. This information was used, in combination with a yeast two-hybrid analysis of SIRV2 protein interactions, to advance current understanding of viral gene functions. As a consequence of SIRV2 infection, transcription of more than one-third of S. islandicus genes was differentially regulated. While expression of genes involved in cell division decreased, those genes playing a role in antiviral defense were activated on a large scale. Expression of genes belonging to toxin-antitoxin and clustered regularly interspaced short palindromic repeat (CRISPR)-Cas systems was specifically pronounced. The observed different degree of activation of various CRISPR-Cas systems highlights the specialized functions they perform. The information on individual gene expression and activation of antiviral defense systems is expected to aid future studies aimed at detailed understanding of the functions and interplay of these systems in vivo.
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Jaubert C, Danioux C, Oberto J, Cortez D, Bize A, Krupovic M, She Q, Forterre P, Prangishvili D, Sezonov G. Genomics and genetics of Sulfolobus islandicus LAL14/1, a model hyperthermophilic archaeon. Open Biol 2013; 3:130010. [PMID: 23594878 PMCID: PMC3718332 DOI: 10.1098/rsob.130010] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The 2 465 177 bp genome of Sulfolobus islandicus LAL14/1, host of the model rudivirus SIRV2, was sequenced. Exhaustive comparative genomic analysis of S. islandicus LAL14/1 and the nine other completely sequenced S. islandicus strains isolated from Iceland, Russia and USA revealed a highly syntenic common core genome of approximately 2 Mb and a long hyperplastic region containing most of the strain-specific genes. In LAL14/1, the latter region is enriched in insertion sequences, CRISPR (clustered regularly interspaced short palindromic repeats), glycosyl transferase genes, toxin-antitoxin genes and MITE (miniature inverted-repeat transposable elements). The tRNA genes of LAL14/1 are preferential targets for the integration of mobile elements but clusters of atypical genes (CAG) are also integrated elsewhere in the genome. LAL14/1 carries five CRISPR loci with 10 per cent of spacers matching perfectly or imperfectly the genomes of archaeal viruses and plasmids found in the Icelandic hot springs. Strikingly, the CRISPR_2 region of LAL14/1 carries an unusually long 1.9 kb spacer interspersed between two repeat regions and displays a high similarity to pING1-like conjugative plasmids. Finally, we have developed a genetic system for S. islandicus LAL14/1 and created ΔpyrEF and ΔCRISPR_1 mutants using double cross-over and pop-in/pop-out approaches, respectively. Thus, LAL14/1 is a promising model to study virus-host interactions and the CRISPR/Cas defence mechanism in Archaea.
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Affiliation(s)
- Carole Jaubert
- Département de Microbiologie, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Institut Pasteur, Paris, France
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Okutan E, Deng L, Mirlashari S, Uldahl K, Halim M, Liu C, Garrett RA, She Q, Peng X. Novel insights into gene regulation of the rudivirus SIRV2 infecting Sulfolobus cells. RNA Biol 2013; 10:875-85. [PMID: 23584138 DOI: 10.4161/rna.24537] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Microarray analysis of infection by a lytic Sulfolobus rudivirus, SIRV2, revealed both the temporal expression of viral genes and the differential regulation of host genes. A highly susceptible strain derived from Sulfolobus solfataricus P2 with a large genomic deletion spanning CRISPR clusters A to D was infected with SIRV2, and subjected to a microarray analysis. Transcripts from a few viral genes were detected at 15 min post-infection and all except one were expressed within 2 h. The earliest expressed genes were located mainly at the termini of the linear viral genome while later expressed genes were concentrated in the central region. Timing of the expression correlated with the known or predicted functions of the viral gene products and, thus, should facilitate functional characterization of many hypothetical viral genes. Evaluation of the microarray data with quantitative reverse-transcription PCR analyses of a few selected viral genes revealed a good correlation between the two methods. Expression of about 3,000 host genes was examined. Seventy-two were downregulated>2-fold that were mainly associated with stress response and vesicle formation, as well as chromosome structure maintenance, which appears to contribute to host chromosome degradation and cellular collapse. A further 76 host genes were upregulated>2-fold and they were dominated by genes associated with metabolism and membrane transport, including phosphate transport and DNA precursor synthesis. The altered transcriptional patterns suggest that the virus reprograms the host cellular machinery to facilitate its own DNA replication and to inhibit cellular processes required for defense against viruses.
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Affiliation(s)
- Ebru Okutan
- Archaea Centre, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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