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Kuiper BP, Schöntag AMC, Oksanen HM, Daum B, Quax TEF. Archaeal virus entry and egress. MICROLIFE 2024; 5:uqad048. [PMID: 38234448 PMCID: PMC10791045 DOI: 10.1093/femsml/uqad048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 11/08/2023] [Accepted: 01/02/2024] [Indexed: 01/19/2024]
Abstract
Archaeal viruses display a high degree of structural and genomic diversity. Few details are known about the mechanisms by which these viruses enter and exit their host cells. Research on archaeal viruses has lately made significant progress due to advances in genetic tools and imaging techniques, such as cryo-electron tomography (cryo-ET). In recent years, a steady output of newly identified archaeal viral receptors and egress mechanisms has offered the first insight into how archaeal viruses interact with the archaeal cell envelope. As more details about archaeal viral entry and egress are unravelled, patterns are starting to emerge. This helps to better understand the interactions between viruses and the archaeal cell envelope and how these compare to infection strategies of viruses in other domains of life. Here, we provide an overview of recent developments in the field of archaeal viral entry and egress, shedding light onto the most elusive part of the virosphere.
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Affiliation(s)
- Bastiaan P Kuiper
- Biology of Archaea and Viruses, Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, Faculty for Science and Engineering, University of Groningen, 7th floor, Nijenborgh 7, 9747 AG Groningen, the Netherlands
| | - Anna M C Schöntag
- Biology of Archaea and Viruses, Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, Faculty for Science and Engineering, University of Groningen, 7th floor, Nijenborgh 7, 9747 AG Groningen, the Netherlands
| | - Hanna M Oksanen
- Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Viikinkaari 9, FI-00014 Helsinki, Finland
| | - Bertram Daum
- Living Systems Institute, Faculty of Health and Life Sciences, University of Exeter, Exeter EX4 4QD, United Kingdom
| | - Tessa E F Quax
- Biology of Archaea and Viruses, Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, Faculty for Science and Engineering, University of Groningen, 7th floor, Nijenborgh 7, 9747 AG Groningen, the Netherlands
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2
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Zhang W, Bhoobalan-Chitty Y, Zhai X, Hui Y, Hansen LH, Deng L, Peng X. Replication Protein Rep Provides Selective Advantage to Viruses in the Presence of CRISPR-Cas Immunity. CRISPR J 2023; 6:32-42. [PMID: 36576859 DOI: 10.1089/crispr.2022.0037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Anti-Clustered regularly interspaced small palindromic repeat (CRISPR) (Acr) phages cooperate to establish a successful infection in CRISPR-containing host. We report here the selective advantage provided by a replication initiator, Rep, toward cooperative host immunosuppression by viruses encoding Acrs. A rep knockout mutant (Δgp16) of Sulfolobus islandicus rod-shaped virus 2 produced around fourfold less virus in a CRISPR-null host, suggesting that Rep is the major replication initiator. In addition to Rep-dependent replication initiation from the viral genomic termini, we detected Rep-independent replication initiation from nonterminal sites. Intriguingly, despite the presence of Acrs, lack of Rep showed a profound effect on virus propagation in a host carrying CRISPR-Cas immunity. Accordingly, the co-infecting parental virus (rep-containing) outcompeted the Δgp16 mutant much more quickly in the CRISPR-containing host than in CRISPR-null host. Despite the nonessentiality, rep is carried by all known members of Rudiviridae, which is likely an evolutionary outcome driven by the ubiquitous presence of CRISPR-Cas in Sulfolobales.
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Affiliation(s)
- Weijia Zhang
- Department of Biology, University of Copenhagen, Copenhagen N, Denmark
| | | | - Xichuan Zhai
- Department of Food Science, University of Copenhagen, Frederiksberg, Denmark
| | - Yan Hui
- Department of Food Science, University of Copenhagen, Frederiksberg, Denmark
| | - Lars Hestbjerg Hansen
- Department of Plant and Environmental Science, University of Copenhagen, Frederiksberg, Denmark
| | - Ling Deng
- Department of Food Science, University of Copenhagen, Frederiksberg, Denmark
| | - Xu Peng
- Department of Biology, University of Copenhagen, Copenhagen N, Denmark
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3
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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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A filamentous archaeal virus is enveloped inside the cell and released through pyramidal portals. Proc Natl Acad Sci U S A 2021; 118:2105540118. [PMID: 34341107 DOI: 10.1073/pnas.2105540118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The majority of viruses infecting hyperthermophilic archaea display unique virion architectures and are evolutionarily unrelated to viruses of bacteria and eukaryotes. The lack of relationships to other known viruses suggests that the mechanisms of virus-host interaction in Archaea are also likely to be distinct. To gain insights into archaeal virus-host interactions, we studied the life cycle of the enveloped, ∼2-μm-long Sulfolobus islandicus filamentous virus (SIFV), a member of the family Lipothrixviridae infecting a hyperthermophilic and acidophilic archaeon Saccharolobus islandicus LAL14/1. Using dual-axis electron tomography and convolutional neural network analysis, we characterize the life cycle of SIFV and show that the virions, which are nearly two times longer than the host cell diameter, are assembled in the cell cytoplasm, forming twisted virion bundles organized on a nonperfect hexagonal lattice. Remarkably, our results indicate that envelopment of the helical nucleocapsids takes place inside the cell rather than by budding as in the case of most other known enveloped viruses. The mature virions are released from the cell through large (up to 220 nm in diameter), six-sided pyramidal portals, which are built from multiple copies of a single 89-amino-acid-long viral protein gp43. The overexpression of this protein in Escherichia coli leads to pyramid formation in the bacterial membrane. Collectively, our results provide insights into the assembly and release of enveloped filamentous viruses and illuminate the evolution of virus-host interactions in Archaea.
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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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Bhoobalan-Chitty Y, Johansen TB, Di Cianni N, Peng X. Inhibition of Type III CRISPR-Cas Immunity by an Archaeal Virus-Encoded Anti-CRISPR Protein. Cell 2019; 179:448-458.e11. [PMID: 31564454 DOI: 10.1016/j.cell.2019.09.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 07/23/2019] [Accepted: 09/03/2019] [Indexed: 12/26/2022]
Abstract
Bacteria and archaea possess a striking diversity of CRISPR-Cas systems divided into six types, posing a significant barrier to viral infection. As part of the virus-host arms race, viruses encode protein inhibitors of type I, II, and V CRISPR-Cas systems, but whether there are natural inhibitors of the other, mechanistically distinct CRISPR-Cas types is unknown. Here, we present the discovery of a type III CRISPR-Cas inhibitor, AcrIIIB1, encoded by the Sulfolobus virus SIRV2. AcrIIIB1 exclusively inhibits CRISPR-Cas subtype III-B immunity mediated by the RNase activity of the accessory protein Csx1. AcrIIIB1 does not appear to bind Csx1 but, rather, interacts with two distinct subtype III-B effector complexes-Cmr-α and Cmr-γ-which, in response to protospacer transcript binding, are known to synthesize cyclic oligoadenylates (cOAs) that activate the Csx1 "collateral" RNase. Taken together, we infer that AcrIIIB1 inhibits type III-B CRISPR-Cas immunity by interfering with a Csx1 RNase-related process.
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Affiliation(s)
- Yuvaraj Bhoobalan-Chitty
- Danish Archaea Centre, Department of Biology, University of Copenhagen, Copenhagen N, Denmark; Centre for Bacterial Stress Response and Persistence, Department of Biology, University of Copenhagen, Copenhagen N, Denmark
| | - Thomas Baek Johansen
- Danish Archaea Centre, Department of Biology, University of Copenhagen, Copenhagen N, Denmark
| | - Nadia Di Cianni
- Danish Archaea Centre, Department of Biology, University of Copenhagen, Copenhagen N, Denmark
| | - Xu Peng
- Danish Archaea Centre, Department of Biology, University of Copenhagen, Copenhagen N, Denmark; Centre for Bacterial Stress Response and Persistence, Department of Biology, University of Copenhagen, Copenhagen N, Denmark.
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Tomaska L, Nosek J, Kar A, Willcox S, Griffith JD. A New View of the T-Loop Junction: Implications for Self-Primed Telomere Extension, Expansion of Disease-Related Nucleotide Repeat Blocks, and Telomere Evolution. Front Genet 2019; 10:792. [PMID: 31475042 PMCID: PMC6702307 DOI: 10.3389/fgene.2019.00792] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 07/26/2019] [Indexed: 12/12/2022] Open
Abstract
Telomere loops (t-loops) are formed at the ends of chromosomes in species ranging from humans to worms, plants, and with genetic manipulation, some yeast. Recent in vitro studies demonstrated that transcription of telomeric DNA leads to highly efficient t-loop formation. It was also shown that both DNA termini are inserted into the preceding DNA to generate a highly stable t-loop junction. Furthermore, some telomeric RNA remains present at the junction, potentially acting as a plug to further protect and stabilize the t-loop. Modeling the loop junction reveals two mechanisms by which the canonical chromosomal replication factors could extend the telomere in the absence of telomerase. One mechanism would utilize the annealed 3’ terminus as a de novo replication origin. In vitro evidence for the ability of the t-loop to prime telomere extension using the T7 replication factors is presented. A second mechanism would involve resolution of the Holliday junction present in the t-loop bubble by factors such as GEN1 to generate a rolling circle template at the extreme terminus of the telomere. This could lead to large expansions of the telomeric tract. Here, we propose that telomeres evolved as terminal elements containing long arrays of short nucleotide repeats due to the ability of such arrays to fold back into loops and self-prime their replicative extension. In this view, telomerase may have evolved later to provide a more precise mechanism of telomere maintenance. Both pathways have direct relevance to the alternative lengthening of telomeres (ALT) pathway. This view also provides a possible mechanism for the very large repeat expansions observed in nucleotide repeat diseases such as Fragile X syndrome, myotonic dystrophy, familial amyotrophic lateral sclerosis (ALS), and frontotemporal dementia (FTD). The evolution of telomeres is discussed in the framework of these models.
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Affiliation(s)
- Lubomir Tomaska
- Departments of Genetics and Biochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Bratislava, Slovakia
| | - Jozef Nosek
- Departments of Genetics and Biochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Bratislava, Slovakia
| | - Anirban Kar
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Smaranda Willcox
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Jack D Griffith
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
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Wang Y, Chen B, Cao M, Sima L, Prangishvili D, Chen X, Krupovic M. Rolling-circle replication initiation protein of haloarchaeal sphaerolipovirus SNJ1 is homologous to bacterial transposases of the IS91 family insertion sequences. J Gen Virol 2018; 99:416-421. [DOI: 10.1099/jgv.0.001009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Affiliation(s)
- Yuchen Wang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, PR China
| | - Beibei Chen
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, PR China
| | - Mengzhuo Cao
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, PR China
| | - Linshan Sima
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, PR China
| | - David Prangishvili
- Department of Microbiology, Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Paris, France
| | - Xiangdong Chen
- China Center for Type Culture Collection, Wuhan, PR China
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, PR China
| | - Mart Krupovic
- Department of Microbiology, Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Paris, France
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Krupovic M, Cvirkaite-Krupovic V, Iranzo J, Prangishvili D, Koonin EV. Viruses of archaea: Structural, functional, environmental and evolutionary genomics. Virus Res 2017; 244:181-193. [PMID: 29175107 DOI: 10.1016/j.virusres.2017.11.025] [Citation(s) in RCA: 139] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 11/20/2017] [Accepted: 11/20/2017] [Indexed: 11/18/2022]
Abstract
Viruses of archaea represent one of the most enigmatic parts of the virosphere. Most of the characterized archaeal viruses infect extremophilic hosts and display remarkable diversity of virion morphotypes, many of which have never been observed among viruses of bacteria or eukaryotes. The uniqueness of the virion morphologies is matched by the distinctiveness of the genomes of these viruses, with ∼75% of genes encoding unique proteins, refractory to functional annotation based on sequence analyses. In this review, we summarize the state-of-the-art knowledge on various aspects of archaeal virus genomics. First, we outline how structural and functional genomics efforts provided valuable insights into the functions of viral proteins and revealed intricate details of the archaeal virus-host interactions. We then highlight recent metagenomics studies, which provided a glimpse at the diversity of uncultivated viruses associated with the ubiquitous archaea in the oceans, including Thaumarchaeota, Marine Group II Euryarchaeota, and others. These findings, combined with the recent discovery that archaeal viruses mediate a rapid turnover of thaumarchaea in the deep sea ecosystems, illuminate the prominent role of these viruses in the biosphere. Finally, we discuss the origins and evolution of archaeal viruses and emphasize the evolutionary relationships between viruses and non-viral mobile genetic elements. Further exploration of the archaeal virus diversity as well as functional studies on diverse virus-host systems are bound to uncover novel, unexpected facets of the archaeal virome.
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Affiliation(s)
- Mart Krupovic
- Department of Microbiology, Institut Pasteur, 25 rue du Dr. Roux, Paris 75015, Paris, France.
| | | | - Jaime Iranzo
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD, USA
| | - David Prangishvili
- Department of Microbiology, Institut Pasteur, 25 rue du Dr. Roux, Paris 75015, Paris, France
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD, USA
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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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Identification, Characterization, and Application of the Replicon Region of the Halophilic Temperate Sphaerolipovirus SNJ1. J Bacteriol 2016; 198:1952-1964. [PMID: 27137505 DOI: 10.1128/jb.00131-16] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 04/26/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The temperate haloarchaeal virus SNJ1 displays lytic and lysogenic life cycles. During the lysogenic cycle, the virus resides in its host, Natrinema sp. strain J7-1, in the form of an extrachromosomal circular plasmid, pHH205. In this study, a 3.9-kb region containing seven predicted genes organized in two operons was identified as the minimal replicon of SNJ1. Only RepA, encoded by open reading frame 11-12 (ORF11-12), was found to be essential for replication, and its expression increased during the lytic cycle. Sequence analysis suggested that RepA is a distant homolog of HUH endonucleases, a superfamily that includes rolling-circle replication initiation proteins from various viruses and plasmids. In addition to RepA, two genetic elements located within both termini of the 3.9-kb replicon were also required for SNJ1 replication. SNJ1 genome and SNJ1 replicon-based shuttle vectors were present at 1 to 3 copies per chromosome. However, the deletion of ORF4 significantly increased the SNJ1 copy number, suggesting that the product of ORF4 is a negative regulator of SNJ1 abundance. Shuttle vectors based on the SNJ1 replicon were constructed and validated for stable expression of heterologous proteins, both in J7 derivatives and in Natrinema pallidum JCM 8980(T), suggesting their broad applicability as genetic tools for Natrinema species. IMPORTANCE Archaeal viruses exhibit striking morphological diversity and unique gene content. In this study, the minimal replicon of the temperate haloarchaeal virus SNJ1 was identified. A number of ORFs and genetic elements controlling virus genome replication, maintenance, and copy number were characterized. In addition, based on the replicon, a novel expression shuttle vector has been constructed and validated for protein expression and purification in Natrinema sp. CJ7 and Natrinema pallidum JCM 8980(T) This study not only provided mechanistic and functional insights into SNJ1 replication but also led to the development of useful genetic tools to investigate SNJ1 and other viruses infecting Natrinema species as well as their hosts.
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Kazlauskas D, Krupovic M, Venclovas Č. The logic of DNA replication in double-stranded DNA viruses: insights from global analysis of viral genomes. Nucleic Acids Res 2016; 44:4551-64. [PMID: 27112572 PMCID: PMC4889955 DOI: 10.1093/nar/gkw322] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 04/13/2016] [Indexed: 11/14/2022] Open
Abstract
Genomic DNA replication is a complex process that involves multiple proteins. Cellular DNA replication systems are broadly classified into only two types, bacterial and archaeo-eukaryotic. In contrast, double-stranded (ds) DNA viruses feature a much broader diversity of DNA replication machineries. Viruses differ greatly in both completeness and composition of their sets of DNA replication proteins. In this study, we explored whether there are common patterns underlying this extreme diversity. We identified and analyzed all major functional groups of DNA replication proteins in all available proteomes of dsDNA viruses. Our results show that some proteins are common to viruses infecting all domains of life and likely represent components of the ancestral core set. These include B-family polymerases, SF3 helicases, archaeo-eukaryotic primases, clamps and clamp loaders of the archaeo-eukaryotic type, RNase H and ATP-dependent DNA ligases. We also discovered a clear correlation between genome size and self-sufficiency of viral DNA replication, the unanticipated dominance of replicative helicases and pervasive functional associations among certain groups of DNA replication proteins. Altogether, our results provide a comprehensive view on the diversity and evolution of replication systems in the DNA virome and uncover fundamental principles underlying the orchestration of viral DNA replication.
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Affiliation(s)
- Darius Kazlauskas
- Institute of Biotechnology, Vilnius University, Vilnius LT-02241, Lithuania
| | - Mart Krupovic
- Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Department of Microbiology, Institut Pasteur, Paris 75015, France
| | - Česlovas Venclovas
- Institute of Biotechnology, Vilnius University, Vilnius LT-02241, Lithuania
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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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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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15
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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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