1
|
Yutin N, Mutz P, Krupovic M, Koonin EV. Mriyaviruses: small relatives of giant viruses. mBio 2024; 15:e0103524. [PMID: 38832788 PMCID: PMC11253617 DOI: 10.1128/mbio.01035-24] [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: 04/06/2024] [Accepted: 05/01/2024] [Indexed: 06/05/2024] Open
Abstract
The phylum Nucleocytoviricota consists of large and giant viruses that range in genome size from about 100 kilobases (kb) to more than 2.5 megabases. Here, using metagenome mining followed by extensive phylogenomic analysis and protein structure comparison, we delineate a distinct group of viruses with double-stranded (ds) DNA genomes in the range of 35-45 kb that appear to be related to the Nucleocytoviricota. In phylogenetic trees of the conserved double jelly-roll major capsid proteins (MCPs) and DNA packaging ATPases, these viruses do not show affinity to any particular branch of the Nucleocytoviricota and accordingly would comprise a class which we propose to name "Mriyaviricetes" (after Ukrainian "mriya," dream). Structural comparison of the MCP suggests that, among the extant virus lineages, mriyaviruses are the closest one to the ancestor of the Nucleocytoviricota. In the phylogenetic trees, mriyaviruses split into two well-separated branches, the family Yaraviridae and proposed new family "Gamadviridae." The previously characterized members of these families, yaravirus and Pleurochrysis sp. endemic viruses, infect amoeba and haptophytes, respectively. The genomes of the rest of the mriyaviruses were assembled from metagenomes from diverse environments, suggesting that mriyaviruses infect various unicellular eukaryotes. Mriyaviruses lack DNA polymerase, which is encoded by all other members of the Nucleocytoviricota, and RNA polymerase subunits encoded by all cytoplasmic viruses among the Nucleocytoviricota, suggesting that they replicate in the host cell nuclei. All mriyaviruses encode a HUH superfamily endonuclease that is likely to be essential for the initiation of virus DNA replication via the rolling circle mechanism. IMPORTANCE The origin of giant viruses of eukaryotes that belong to the phylum Nucleocytoviricota is not thoroughly understood and remains a matter of major interest and debate. Here, we combine metagenome database searches with extensive protein sequence and structure analysis to describe a distinct group of viruses with comparatively small genomes of 35-45 kilobases that appear to comprise a distinct class within the phylum Nucleocytoviricota that we provisionally named "Mriyaviricetes." Mriyaviruses appear to be the closest identified relatives of the ancestors of the Nucleocytoviricota. Analysis of proteins encoded in mriyavirus genomes suggests that they replicate their genome via the rolling circle mechanism that is unusual among viruses with double-stranded DNA genomes and so far not described for members of Nucleocytoviricota.
Collapse
Affiliation(s)
- Natalya Yutin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, Maryland, USA
| | - Pascal Mutz
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, Maryland, USA
| | - Mart Krupovic
- Institut Pasteur, Université Paris Cité, Archaeal Virology Unit, Paris, France
| | - Eugene V. Koonin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, Maryland, USA
| |
Collapse
|
2
|
Yutin N, Mutz P, Krupovic M, Koonin EV. Mriyaviruses: Small Relatives of Giant Viruses. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.29.582850. [PMID: 38529486 PMCID: PMC10962738 DOI: 10.1101/2024.02.29.582850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/27/2024]
Abstract
The phylum Nucleocytoviricota consists of large and giant viruses that range in genome size from about 100 kilobases (kb) to more than 2.5 megabases. Here, using metagenome mining followed by extensive phylogenomic analysis and protein structure comparison, we delineate a distinct group of viruses with double-stranded (ds) DNA genomes in the range of 35-45 kb that appear to be related to the Nucleocytoviricota. In phylogenetic trees of the conserved double jelly-roll major capsid proteins (MCP) and DNA packaging ATPases, these viruses do not show affinity to any particular branch of the Nucleocytoviricota and accordingly would comprise a class which we propose to name "Mriyaviricetes" (after Ukrainian Mriya, dream). Structural comparison of the MCP suggests that, among the extant virus lineages, mriyaviruses are the closest one to the ancestor of the Nucleocytoviricota. In the phylogenetic trees, mriyaviruses split into two well-separated branches, the family Yaraviridae and proposed new family "Gamadviridae". The previously characterized members of these families, Yaravirus and Pleurochrysis sp. endemic viruses, infect amoeba and haptophytes, respectively. The genomes of the rest of the mriyaviruses were assembled from metagenomes from diverse environments, suggesting that mriyaviruses infect various unicellular eukaryotes. Mriyaviruses lack DNA polymerase, which is encoded by all other members of the Nucleocytoviricota, and RNA polymerase subunits encoded by all cytoplasmic viruses among the Nucleocytoviricota, suggesting that they replicate in the host cell nuclei. All mriyaviruses encode a HUH superfamily endonuclease that is likely to be essential for the initiation of virus DNA replication via the rolling circle mechanism.
Collapse
Affiliation(s)
- Natalya Yutin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
| | - Pascal Mutz
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
| | - Mart Krupovic
- Institut Pasteur, Université Paris Cité, Archaeal Virology Unit, Paris 75015, France
| | - Eugene V. Koonin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
| |
Collapse
|
3
|
Liu Y, Du S, Chen X, Dyall-Smith M, Jalasvuori M, Oksanen HM. ICTV Virus Taxonomy Profile: Simuloviridae 2023. J Gen Virol 2023; 104. [PMID: 37093734 DOI: 10.1099/jgv.0.001841] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023] Open
Abstract
The family Simuloviridae includes tailless icosahedral viruses with an internal lipid membrane. The capsid is constructed from two major capsid proteins, both with a single jelly-roll fold. The genome is a circular dsDNA molecule of 16-19 kb. All members infect halophilic archaea in the class Halobacteria (phylum Euryarchaeota) and are temperate viruses, their proviruses residing in host cells as extrachromosomal episomes. Once the lytic life cycle is triggered, production of virions causes cell lysis. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Simuloviridae, which is available at ictv.global/report/simuloviridae.
Collapse
Affiliation(s)
- Ying Liu
- Archaeal Virology Unit, Institut Pasteur, Université Paris Cité, CNRS UMR6047, Paris, France
| | - Shishen Du
- Department of Microbiology, College of Life Sciences, Wuhan University, Wuhan 430072, PR China
| | - Xiangdong Chen
- Department of Microbiology, College of Life Sciences, Wuhan University, Wuhan 430072, PR China
| | - Mike Dyall-Smith
- Computational Biology Group, Max Planck Institute of Biochemistry, Martinsried, Germany
- Veterinary Biosciences, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Australia
| | - Matti Jalasvuori
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
| | - Hanna M Oksanen
- Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| |
Collapse
|
4
|
The Baltimore Classification of Viruses 50 Years Later: How Does It Stand in the Light of Virus Evolution? Microbiol Mol Biol Rev 2021; 85:e0005321. [PMID: 34259570 DOI: 10.1128/mmbr.00053-21] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Fifty years ago, David Baltimore published a brief conceptual paper delineating the classification of viruses by the routes of genome expression. The six "Baltimore classes" of viruses, with a subsequently added 7th class, became the conceptual framework for the development of virology during the next five decades. During this time, it became clear that the Baltimore classes, with relatively minor additions, indeed cover the diversity of virus genome expression schemes that also define the replication cycles. Here, we examine the status of the Baltimore classes 50 years after their advent and explore their links with the global ecology and biology of the respective viruses. We discuss an extension of the Baltimore scheme and why many logically admissible expression-replication schemes do not appear to be realized in nature. Recent phylogenomic analyses allow tracing the complex connections between the Baltimore classes and the monophyletic realms of viruses. The five classes of RNA viruses and reverse-transcribing viruses share an origin, whereas both the single-stranded DNA viruses and double-stranded DNA (dsDNA) viruses evolved on multiple independent occasions. Most of the Baltimore classes of viruses probably emerged during the earliest era of life evolution, at the stage of the primordial pool of diverse replicators, and before the advent of modern-like cells with large dsDNA genomes. The Baltimore classes remain an integral part of the conceptual foundation of biology, providing the essential structure for the logical space of information transfer processes, which is nontrivially connected with the routes of evolution of viruses and other replicators.
Collapse
|
5
|
Chen B, Chen Z, Wang Y, Gong H, Sima L, Wang J, Ouyang S, Gan W, Krupovic M, Chen X, Du S. ORF4 of the Temperate Archaeal Virus SNJ1 Governs the Lysis-Lysogeny Switch and Superinfection Immunity. J Virol 2020; 94:e00841-20. [PMID: 32522850 PMCID: PMC7394903 DOI: 10.1128/jvi.00841-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 06/01/2020] [Indexed: 12/21/2022] Open
Abstract
Recent environmental and metagenomic studies have considerably increased the repertoire of archaeal viruses and suggested that they play important roles in nutrient cycling in the biosphere. However, very little is known about how they regulate their life cycles and interact with their hosts. Here, we report that the life cycle of the temperate haloarchaeal virus SNJ1 is controlled by the product ORF4, a small protein belonging to the antitoxin MazE superfamily. We show that ORF4 controls the lysis-lysogeny switch of SNJ1 and mediates superinfection immunity by repression of genomic DNA replication of the superinfecting viruses. Bioinformatic analysis shows that ORF4 is highly conserved in two SNJ1-like proviruses, suggesting that the mechanisms for lysis-lysogeny switch and superinfection immunity are conserved in this group of viruses. As the lysis-lysogeny switch and superinfection immunity of archaeal viruses have been poorly studied, we suggest that SNJ1 could serve as a model system to study these processes.IMPORTANCE Archaeal viruses are important parts of the virosphere. Understanding how they regulate their life cycles and interact with host cells provide crucial insights into their biological functions and the evolutionary histories of viruses. However, mechanistic studies of the life cycle of archaeal viruses are scarce due to a lack of genetic tools and demanding cultivation conditions. Here, we discover that the temperate haloarchaeal virus SNJ1, which infects Natrinema sp. strain J7, employs a lysis-lysogeny switch and establishes superinfection immunity like bacteriophages. We show that its ORF4 is critical for both processes and acts as a repressor of the replication of SNJ1. These results establish ORF4 as a master regulator of SNJ1 life cycle and provides novel insights on the regulation of life cycles by temperate archaeal viruses and on their interactions with host cells.
Collapse
Affiliation(s)
- Beibei Chen
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Zhao Chen
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Yuchen Wang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Han Gong
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Linshan Sima
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Jiao Wang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Shushan Ouyang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Wenqiang Gan
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Mart Krupovic
- Department of Microbiology, Institut Pasteur, Paris, France
| | - Xiangdong Chen
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Shishen Du
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| |
Collapse
|
6
|
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: 108] [Impact Index Per Article: 21.6] [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.
Collapse
|
7
|
Mizuno CM, Prajapati B, Lucas‐Staat S, Sime‐Ngando T, Forterre P, Bamford DH, Prangishvili D, Krupovic M, Oksanen HM. Novel haloarchaeal viruses from Lake Retba infecting
Haloferax
and
Halorubrum
species. Environ Microbiol 2019; 21:2129-2147. [DOI: 10.1111/1462-2920.14604] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 03/15/2019] [Accepted: 03/21/2019] [Indexed: 11/30/2022]
Affiliation(s)
- Carolina M. Mizuno
- Unité Biologie Moléculaire du Gène chez les ExtrêmophilesInstitut Pasteur, 25 rue du Docteur Roux 75015, Paris France
| | - Bina Prajapati
- Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental SciencesUniversity of Helsinki Finland
| | - Soizick Lucas‐Staat
- Unité Biologie Moléculaire du Gène chez les ExtrêmophilesInstitut Pasteur, 25 rue du Docteur Roux 75015, Paris France
| | - Telesphore Sime‐Ngando
- CNRS UMR 6023, Université Clermont‐AuvergneLaboratoire "Microorganismes: Génome et Environnement" (LMGE) F‐63000, Clermont‐Ferrand France
| | - Patrick Forterre
- Unité Biologie Moléculaire du Gène chez les ExtrêmophilesInstitut Pasteur, 25 rue du Docteur Roux 75015, Paris France
| | - Dennis H. Bamford
- Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental SciencesUniversity of Helsinki Finland
| | - David Prangishvili
- Unité Biologie Moléculaire du Gène chez les ExtrêmophilesInstitut Pasteur, 25 rue du Docteur Roux 75015, Paris France
| | - Mart Krupovic
- Unité Biologie Moléculaire du Gène chez les ExtrêmophilesInstitut Pasteur, 25 rue du Docteur Roux 75015, Paris France
| | - Hanna M. Oksanen
- Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental SciencesUniversity of Helsinki Finland
| |
Collapse
|
8
|
Krupovic M, Makarova KS, Wolf YI, Medvedeva S, Prangishvili D, Forterre P, Koonin EV. Integrated mobile genetic elements in Thaumarchaeota. Environ Microbiol 2019; 21:2056-2078. [PMID: 30773816 PMCID: PMC6563490 DOI: 10.1111/1462-2920.14564] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 02/10/2019] [Accepted: 02/13/2019] [Indexed: 12/20/2022]
Abstract
To explore the diversity of mobile genetic elements (MGE) associated with archaea of the phylum Thaumarchaeota, we exploited the property of most MGE to integrate into the genomes of their hosts. Integrated MGE (iMGE) were identified in 20 thaumarchaeal genomes amounting to 2 Mbp of mobile thaumarchaeal DNA. These iMGE group into five major classes: (i) proviruses, (ii) casposons, (iii) insertion sequence-like transposons, (iv) integrative-conjugative elements and (v) cryptic integrated elements. The majority of the iMGE belong to the latter category and might represent novel families of viruses or plasmids. The identified proviruses are related to tailed viruses of the order Caudovirales and to tailless icosahedral viruses with the double jelly-roll capsid proteins. The thaumarchaeal iMGE are all connected within a gene sharing network, highlighting pervasive gene exchange between MGE occupying the same ecological niche. The thaumarchaeal mobilome carries multiple auxiliary metabolic genes, including multicopper oxidases and ammonia monooxygenase subunit C (AmoC), and stress response genes, such as those for universal stress response proteins (UspA). Thus, iMGE might make important contributions to the fitness and adaptation of their hosts. We identified several iMGE carrying type I-B CRISPR-Cas systems and spacers matching other thaumarchaeal iMGE, suggesting antagonistic interactions between coexisting MGE and symbiotic relationships with the ir archaeal hosts.
Collapse
Affiliation(s)
- Mart Krupovic
- Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, 75015, Paris, France
| | - Kira S Makarova
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
| | - Yuri I Wolf
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
| | - Sofia Medvedeva
- Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, 75015, Paris, France.,Center of Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo, Russia.,Sorbonne Université, Collège doctoral, 75005, Paris, France
| | - David Prangishvili
- Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, 75015, Paris, France
| | - Patrick Forterre
- Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, 75015, Paris, France.,Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris- Sud, Université Paris-Saclay, Gif-sur-Yvette cedex, Paris, France
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
| |
Collapse
|
9
|
Heringer P, Kuhn GCS. Exploring the Remote Ties between Helitron Transposases and Other Rolling-Circle Replication Proteins. Int J Mol Sci 2018; 19:E3079. [PMID: 30304800 PMCID: PMC6213432 DOI: 10.3390/ijms19103079] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 09/26/2018] [Accepted: 10/07/2018] [Indexed: 01/30/2023] Open
Abstract
Rolling-circle replication (RCR) elements constitute a diverse group that includes viruses, plasmids, and transposons, present in hosts from all domains of life. Eukaryotic RCR transposons, also known as Helitrons, are found in species from all eukaryotic kingdoms, sometimes representing a large portion of their genomes. Despite the impact of Helitrons on their hosts, knowledge about their relationship with other RCR elements is still elusive. Here, we compared the endonuclease domain sequence of Helitron transposases with the corresponding region from RCR proteins found in a wide variety of mobile genetic elements. To do that, we used a stepwise alignment approach followed by phylogenetic and multidimensional scaling analyses. Although it has been suggested that Helitrons might have originated from prokaryotic transposons or eukaryotic viruses, our results indicate that Helitron transposases share more similarities with proteins from prokaryotic viruses and plasmids instead. We also provide evidence for the division of RCR endonucleases into three groups (Y1, Y2, and Yx), covering the whole diversity of this protein family. Together, these results point to prokaryotic elements as the likely closest ancestors of eukaryotic RCR transposons, and further demonstrate the fluidity that characterizes the boundaries separating viruses, plasmids, and transposons.
Collapse
Affiliation(s)
- Pedro Heringer
- Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, CEP 31270-901, Brazil.
| | - Gustavo C S Kuhn
- Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, CEP 31270-901, Brazil.
| |
Collapse
|
10
|
Dyall-Smith M, Pfeiffer F. The PL6-Family Plasmids of Haloquadratum Are Virus-Related. Front Microbiol 2018; 9:1070. [PMID: 29875763 PMCID: PMC5974055 DOI: 10.3389/fmicb.2018.01070] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 05/04/2018] [Indexed: 02/01/2023] Open
Abstract
Plasmids PL6A and PL6B are both carried by the C23T strain of the square archaeon Haloquadratum walsbyi, and are closely related (76% nucleotide identity), circular, about 6 kb in size, and display the same gene synteny. They are unrelated to other known plasmids and all of the predicted proteins are cryptic in function. Here we describe two additional PL6-related plasmids, pBAJ9-6 and pLT53-7, each carried by distinct isolates of Haloquadratum walsbyi that were recovered from hypersaline waters in Australia. A third PL6-like plasmid, pLTMV-6, was assembled from metavirome data from Lake Tyrell, a salt-lake in Victoria, Australia. Comparison of all five plasmids revealed a distinct plasmid family with strong conservation of gene content and synteny, an average size of 6.2 kb (range 5.8-7.0 kb) and pairwise similarities between 61-79%. One protein (F3) was closely similar to a protein carried by betapleolipoviruses while another (R6) was similar to a predicted AAA-ATPase of His 1 halovirus (His1V_gp16). Plasmid pLT53-7 carried a gene for a FkbM family methyltransferase that was not present in any of the other plasmids. Comparative analysis of all PL6-like plasmids provided better resolution of conserved sequences and coding regions, confirmed the strong link to haloviruses, and showed that their sequences are highly conserved among examples from Haloquadratum isolates and metagenomic data that collectively cover geographically distant locations, indicating that these genetic elements are widespread.
Collapse
Affiliation(s)
- Mike Dyall-Smith
- Computational Biology Group, Max Planck Institute of Biochemistry, Martinsried, Germany.,Department of Veterinary Biosciences, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, VIC, Australia
| | - Friedhelm Pfeiffer
- Computational Biology Group, Max Planck Institute of Biochemistry, Martinsried, Germany
| |
Collapse
|