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IS481EU Shows a New Connection between Eukaryotic and Prokaryotic DNA Transposons. BIOLOGY 2023; 12:biology12030365. [PMID: 36979057 PMCID: PMC10045372 DOI: 10.3390/biology12030365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/03/2023] [Accepted: 02/24/2023] [Indexed: 03/03/2023]
Abstract
DDD/E transposase gene is the most abundant gene in nature and many DNA transposons in all three domains of life use it for their transposition. A substantial number of eukaryotic DNA transposons show similarity to prokaryotic insertion sequences (ISs). The presence of IS481-like DNA transposons was indicated in the genome of Trichomonas vaginalis. Here, we surveyed IS481-like eukaryotic sequences using a bioinformatics approach and report a group of eukaryotic IS481-like DNA transposons, designated IS481EU, from parabasalids including T. vaginalis. The lengths of target site duplications (TSDs) of IS481EU are around 4 bps, around 15 bps, or around 25 bps, and strikingly, these discrete lengths of TSDs can be observed even in a single IS481EU family. Phylogenetic analysis indicated the close relationships of IS481EU with some of the prokaryotic IS481 family members. IS481EU was not well separated from IS3EU/GingerRoot in the phylogenetic analysis, but was distinct from other eukaryotic DNA transposons including Ginger1 and Ginger2. The unique characteristics of IS481EU in protein sequences and the distribution of TSD lengths support its placement as a new superfamily of eukaryotic DNA transposons.
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2
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Devaux CA, Pontarotti P, Nehari S, Raoult D. 'Cannibalism' of exogenous DNA sequences: The ancestral form of adaptive immunity which entails recognition of danger. Front Immunol 2022; 13:989707. [PMID: 36618387 PMCID: PMC9816338 DOI: 10.3389/fimmu.2022.989707] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 12/05/2022] [Indexed: 12/24/2022] Open
Abstract
Adaptive immunity is a sophisticated form of immune response capable of retaining the molecular memory of a very great diversity of target antigens (epitopes) as non-self. It is capable of reactivating itself upon a second encounter with an immunoglobulin or T-cell receptor antigen-binding site with a known epitope that had previously primed the host immune system. It has long been considered that adaptive immunity is a highly evolved form of non-self recognition that appeared quite late in speciation and complemented a more generalist response called innate immunity. Innate immunity offers a relatively non-specific defense (although mediated by sensors that could specifically recognize virus or bacteria compounds) and which does not retain a memory of the danger. But this notion of recent acquisition of adaptive immunity is challenged by the fact that another form of specific recognition mechanisms already existed in prokaryotes that may be able to specifically auto-protect against external danger. This recognition mechanism can be considered a primitive form of specific (adaptive) non-self recognition. It is based on the fact that many archaea and bacteria use a genome editing system that confers the ability to appropriate viral DNA sequences allowing prokaryotes to prevent host damage through a mechanism very similar to adaptive immunity. This is indistinctly called, 'endogenization of foreign DNA' or 'viral DNA predation' or, more pictorially 'DNA cannibalism'. For several years evidence has been accumulating, highlighting the crucial role of endogenization of foreign DNA in the fundamental processes related to adaptive immunity and leading to a change in the dogma that adaptive immunity appeared late in speciation.
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Affiliation(s)
- Christian A. Devaux
- Aix-Marseille University, Institut de recherche pour le développement (IRD), Assistance Publique Hôpitaux de Marseille (APHM), MEPHI, Institut Hospitalo-universitaire (IHU)-Méditerranée Infection, Marseille, France,Department of Biological Sciences, Centre National de la Recherche Scientifique, Centre National de la Recherche Scientifique (CNRS)-SNC5039, Marseille, France,*Correspondence: Christian A. Devaux,
| | - Pierre Pontarotti
- Aix-Marseille University, Institut de recherche pour le développement (IRD), Assistance Publique Hôpitaux de Marseille (APHM), MEPHI, Institut Hospitalo-universitaire (IHU)-Méditerranée Infection, Marseille, France,Department of Biological Sciences, Centre National de la Recherche Scientifique, Centre National de la Recherche Scientifique (CNRS)-SNC5039, Marseille, France
| | - Sephora Nehari
- Aix-Marseille University, Institut de recherche pour le développement (IRD), Assistance Publique Hôpitaux de Marseille (APHM), MEPHI, Institut Hospitalo-universitaire (IHU)-Méditerranée Infection, Marseille, France
| | - Didier Raoult
- Aix-Marseille University, Institut de recherche pour le développement (IRD), Assistance Publique Hôpitaux de Marseille (APHM), MEPHI, Institut Hospitalo-universitaire (IHU)-Méditerranée Infection, Marseille, France
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Palazzo A, Escuder E, D'Addabbo P, Lovero D, Marsano RM. A genomic survey of Tc1-mariner transposons in nematodes suggests extensive horizontal transposon transfer events. Mol Phylogenet Evol 2021; 158:107090. [PMID: 33545274 DOI: 10.1016/j.ympev.2021.107090] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 01/27/2021] [Accepted: 01/27/2021] [Indexed: 01/24/2023]
Abstract
The number of reports concerning horizontal transposon transfers (HTT) in metazoan species is considerably increased, alongside with the exponential growth of genomic sequence data However, our understanding of the mechanisms of such phenomenon is still at an early stage. Nematodes constitute an animal phylum successfully adapted to almost every ecosystem and for this reason could potentially contribute to spreading the genetic information through horizontal transfer. To date, few studies describe HTT of nematode retrotransposons. This is due to the lack of annotation of transposable elements in the sequenced nematode genomes, especially DNA transposons, which are acknowledged as the best horizontal travelers among mobile sequences. We have therefore started a survey of DNA transposons and their possible involvement in HTT in sequenced nematode genomes. Here, we describe 83 new Tc1/mariner elements distributed in 17 nematode species. Among them, nine families were possibly horizontally transferred between nematodes and the most diverse animal species, including ants as preferred partner of HTT. The results obtained suggest that HTT events involving nematodes Tc1/mariner elements are not uncommon, and that nematodes could have a possible role as transposon reservoir that, in turn, can be redistributed among animal genomes. Overall, this could be relevant to understand how the inter-species genetic flows shape the landscape of genetic variation of organisms inhabiting specific environmental communities.
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Affiliation(s)
- Antonio Palazzo
- Dipartimento di Biologia, Università degli Studi di Bari "Aldo Moro", Bari, Italy
| | - Elsa Escuder
- Dipartimento di Biologia, Università degli Studi di Bari "Aldo Moro", Bari, Italy
| | - Pietro D'Addabbo
- Dipartimento di Biologia, Università degli Studi di Bari "Aldo Moro", Bari, Italy
| | - Domenica Lovero
- Dipartimento di Scienze Biomediche ed Oncologia Umana (DIMO), Università degli Studi di Bari "Aldo Moro", Bari, Italy
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4
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Wu LT, Guo MK, Ke SC, Lin YP, Pang YC, Nguyen HTV, Chen CM. Characterization of the Genetic Background of KPC-2-Producing Klebsiella pneumoniae with Insertion Elements Disrupting the ompK36 Porin Gene. Microb Drug Resist 2020; 26:1050-1057. [PMID: 32283046 DOI: 10.1089/mdr.2019.0410] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Affiliation(s)
- Lii-Tzu Wu
- The Institute of Medical Science and Department of Microbiology, China Medical University Hospital, Taichung, Taiwan
| | - Ming-Kai Guo
- The Institute of Medical Science and Department of Microbiology, China Medical University Hospital, Taichung, Taiwan
| | - Se-Chin Ke
- Infection Control Office, Tungs' Taichung MetroHarbor Hospital, Taichung, Taiwan
- Department of Medical Technology, Jen-The Junior College of Medicine, Nursing and Management, Miaoli, Taiwan
| | - Yi-Pei Lin
- Department of Medical Research, Tungs' Taichung MetroHarbor Hospital, Taichung, Taiwan
| | - Yi-Chun Pang
- The Institute of Medical Science and Department of Microbiology, China Medical University Hospital, Taichung, Taiwan
| | - Hong-Thuy Vy Nguyen
- The Institute of Biomedical Sciences College of Medicine, China Medical University, Taichung, Taiwan
| | - Chih-Ming Chen
- Department of Internal Medicine, Tungs' Taichung MetroHarbor Hospital, Taichung, Taiwan
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Chalmers TJ, Wu LE. Transposable Elements Cross Kingdom Boundaries and Contribute to Inflammation and Ageing: Somatic Acquisition of Foreign Transposable Elements as a Catalyst of Genome Instability, Epigenetic Dysregulation, Inflammation, Senescence, and Ageing. Bioessays 2020; 42:e1900197. [PMID: 31994769 DOI: 10.1002/bies.201900197] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 12/23/2019] [Indexed: 01/07/2023]
Abstract
The de-repression of transposable elements (TEs) in mammalian genomes is thought to contribute to genome instability, inflammation, and ageing, yet is viewed as a cell-autonomous event. In contrast to mammalian cells, prokaryotes constantly exchange genetic material through TEs, crossing both cell and species barriers, contributing to rapid microbial evolution and diversity in complex communities such as the mammalian gut. Here, it is proposed that TEs released from prokaryotes in the microbiome or from pathogenic infections regularly cross the kingdom barrier to the somatic cells of their eukaryotic hosts. It is proposed this horizontal transfer of TEs from microbe to host is a stochastic, ongoing catalyst of genome destabilization, resulting in structural and epigenetic variations, and activation of well-evolved host defense mechanisms contributing to inflammation, senescence, and biological ageing. It is proposed that innate immunity pathways defend against the horizontal acquisition of microbial TEs, and that activation of this pathway during horizontal transposon transfer promotes chronic inflammation during ageing. Finally, it is suggested that horizontal acquisition of prokaryotic TEs into mammalian genomes has been masked and subsequently under-reported due to flaws in current sequencing pipelines, and new strategies to uncover these events are proposed.
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Affiliation(s)
| | - Lindsay E Wu
- School of Medical Sciences, UNSW, Sydney, NSW, 2052, Australia
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Sieber KB, Bromley RE, Dunning Hotopp JC. Lateral gene transfer between prokaryotes and eukaryotes. Exp Cell Res 2017; 358:421-426. [PMID: 28189637 DOI: 10.1016/j.yexcr.2017.02.009] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 02/08/2017] [Indexed: 12/24/2022]
Abstract
Lateral gene transfer (LGT) is an all-encompassing term for the movement of DNA between diverse organisms. LGT is synonymous with horizontal gene transfer, and the terms are used interchangeably throughout the scientific literature. While LGT has been recognized within the bacteria domain of life for decades, inter-domain LGTs are being increasingly described. LGTs between bacteria and complex multicellular organisms are of interest because they challenge the long-held dogma that such transfers could only occur in closely-related, single-celled organisms. Scientists will continue to challenge our understanding of LGT as we sequence more, diverse organisms, as we sequence more endosymbiont-colonized arthropods, and as we continue to appreciate LGT events, both young and old.
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Affiliation(s)
- Karsten B Sieber
- Institute for Genome Science, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Robin E Bromley
- Institute for Genome Science, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Julie C Dunning Hotopp
- Institute for Genome Science, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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Piégu B, Guizard S, Yeping T, Cruaud C, Asgari S, Bideshi DK, Federici BA, Bigot Y. Genome sequence of a crustacean iridovirus, IIV31, isolated from the pill bug, Armadillidium vulgare. J Gen Virol 2014; 95:1585-1590. [PMID: 24722681 DOI: 10.1099/vir.0.066076-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Members of the family Iridoviridae are animal viruses that infect only invertebrates and poikilothermic vertebrates. The invertebrate iridovirus 31 (IIV31) was originally isolated from adult pill bugs, Armadillidium vulgare (class Crustacea, order Isopoda, suborder Oniscidea), found in southern California on the campus of the University of California, Riverside, USA. IIV31 virions are icosahedral, have a diameter of about 135 nm, and contain a dsDNA genome 220.222 kbp in length, with 35.09 mol % G+C content and 203 ORFs. Here, we describe the complete genome sequence of this virus and its annotation. This is the eighth genome sequence of an IIV reported.
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Affiliation(s)
- Benoît Piégu
- UMR INRA-CNRS 7247, PRC, Centre INRA Val de Loire, 37380 Nouzilly, France
| | - Sébastien Guizard
- UMR INRA-CNRS 7247, PRC, Centre INRA Val de Loire, 37380 Nouzilly, France
| | - Tan Yeping
- Interdepartmental Graduate Programs in Cell, Molecular and Developmental Biology, University of California, Riverside, CA 92521, USA.,Department of Entomology, Molecular and Developmental Biology, University of California, Riverside, CA 92521, USA
| | - Corinne Cruaud
- CEA/Institut de Génomique GENOSCOPE, 2 Rue Gaston Crémieux, CP 5706, 91057 Evry CEDEX, France
| | - Sassan Asgari
- School of Biological Sciences, University of Queensland, St Lucia, QLD 4072, Australia
| | - Dennis K Bideshi
- California Baptist University, Department of Natural and Mathematical Sciences, 8432 Magnolia Avenue, Riverside, CA 92504, USA.,Department of Entomology, Molecular and Developmental Biology, University of California, Riverside, CA 92521, USA
| | - Brian A Federici
- Interdepartmental Graduate Programs in Cell, Molecular and Developmental Biology, University of California, Riverside, CA 92521, USA.,Department of Entomology, Molecular and Developmental Biology, University of California, Riverside, CA 92521, USA
| | - Yves Bigot
- UMR INRA-CNRS 7247, PRC, Centre INRA Val de Loire, 37380 Nouzilly, France
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8
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Siguier P, Gourbeyre E, Chandler M. Bacterial insertion sequences: their genomic impact and diversity. FEMS Microbiol Rev 2014; 38:865-91. [PMID: 24499397 PMCID: PMC7190074 DOI: 10.1111/1574-6976.12067] [Citation(s) in RCA: 389] [Impact Index Per Article: 38.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 01/19/2014] [Accepted: 01/22/2014] [Indexed: 01/06/2023] Open
Abstract
Insertion sequences (ISs), arguably the smallest and most numerous autonomous transposable elements (TEs), are important players in shaping their host genomes. This review focuses on prokaryotic ISs. We discuss IS distribution and impact on genome evolution. We also examine their effects on gene expression, especially their role in activating neighbouring genes, a phenomenon of particular importance in the recent upsurge of bacterial antibiotic resistance. We explain how ISs are identified and classified into families by a combination of characteristics including their transposases (Tpases), their overall genetic organisation and the accessory genes which some ISs carry. We then describe the organisation of autonomous and nonautonomous IS‐related elements. This is used to illustrate the growing recognition that the boundaries between different types of mobile element are becoming increasingly difficult to define as more are being identified. We review the known Tpase types, their different catalytic activities used in cleaving and rejoining DNA strands during transposition, their organisation into functional domains and the role of this in regulation. Finally, we consider examples of prokaryotic IS domestication. In a more speculative section, we discuss the necessity of constructing more quantitative dynamic models to fully appreciate the continuing impact of TEs on prokaryotic populations.
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Affiliation(s)
- Patricia Siguier
- Laboratoire de Microbiologie et Génétique Moléculaires, Unité Mixte de Recherche 5100, Centre National de Recherche Scientifique, Toulouse Cedex, France
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9
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Gilbert C, Cordaux R. Horizontal transfer and evolution of prokaryote transposable elements in eukaryotes. Genome Biol Evol 2013; 5:822-32. [PMID: 23563966 PMCID: PMC3673617 DOI: 10.1093/gbe/evt057] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Horizontal transfer (HT) of transposable elements (TEs) plays a key role in prokaryotic evolution, and mounting evidence suggests that it has also had an important impact on eukaryotic evolution. Although many prokaryote-to-prokaryote and eukaryote-to-eukaryote HTs of TEs have been characterized, only few cases have been reported between prokaryotes and eukaryotes. Here, we carried out a comprehensive search for all major groups of prokaryotic insertion sequences (ISs) in 430 eukaryote genomes. We uncovered a total of 80 sequences, all deriving from the IS607 family, integrated in the genomes of 14 eukaryote species belonging to four distinct phyla (Amoebozoa, Ascomycetes, Basidiomycetes, and Stramenopiles). Given that eukaryote IS607-like sequences are most closely related to cyanobacterial IS607 and that their phylogeny is incongruent with that of their hosts, we conclude that the presence of IS607-like sequences in eukaryotic genomes is the result of several HT events. Selection analyses further suggest that our ability to detect these prokaryote TEs today in eukaryotes is because HT of these sequences occurred recently and/or some IS607 elements were domesticated after HT, giving rise to new eukaryote genes. Supporting the recent age of some of these HTs, we uncovered intact full-length, potentially active IS607 copies in the amoeba Acanthamoeba castellani. Overall, our study shows that prokaryote-to-eukaryote HT of TEs occurred at relatively low frequency during recent eukaryote evolution and it sets IS607 as the most widespread TE (being present in prokaryotes, eukaryotes, and viruses).
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Affiliation(s)
- Clément Gilbert
- Université de Poitiers, UMR CNRS 7267 Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, Poitiers, France.
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10
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Arkhipova IR, Rodriguez F. Genetic and epigenetic changes involving (retro)transposons in animal hybrids and polyploids. Cytogenet Genome Res 2013; 140:295-311. [PMID: 23899811 DOI: 10.1159/000352069] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Transposable elements (TEs) are discrete genetic units that have the ability to change their location within chromosomal DNA, and constitute a major and rapidly evolving component of eukaryotic genomes. They can be subdivided into 2 distinct types: retrotransposons, which use an RNA intermediate for transposition, and DNA transposons, which move only as DNA. Rapid advances in genome sequencing significantly improved our understanding of TE roles in genome shaping and restructuring, and studies of transcriptomes and epigenomes shed light on the previously unknown molecular mechanisms underlying genetic and epigenetic TE controls. Knowledge of these control systems may be important for better understanding of reticulate evolution and speciation in the context of bringing different genomes together by hybridization and perturbing the established regulatory balance by ploidy changes. See also sister article focusing on plants by Bento et al. in this themed issue.
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Affiliation(s)
- I R Arkhipova
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA 02543, USA. iarkhipova @ mbl.edu
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11
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Piskurek O, Jackson DJ. Transposable elements: from DNA parasites to architects of metazoan evolution. Genes (Basel) 2012; 3:409-22. [PMID: 24704977 PMCID: PMC3899998 DOI: 10.3390/genes3030409] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2012] [Revised: 06/19/2012] [Accepted: 06/25/2012] [Indexed: 01/22/2023] Open
Abstract
One of the most unexpected insights that followed from the completion of the human genome a decade ago was that more than half of our DNA is derived from transposable elements (TEs). Due to advances in high throughput sequencing technologies it is now clear that TEs comprise the largest molecular class within most metazoan genomes. TEs, once categorised as "junk DNA", are now known to influence genomic structure and function by increasing the coding and non-coding genetic repertoire of the host. In this way TEs are key elements that stimulate the evolution of metazoan genomes. This review highlights several lines of TE research including the horizontal transfer of TEs through host-parasite interactions, the vertical maintenance of TEs over long periods of evolutionary time, and the direct role that TEs have played in generating morphological novelty.
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Affiliation(s)
- Oliver Piskurek
- Courant Research Centre Geobiology, Georg-August-University of Göttingen, Goldschmidtstr. 3, Göttingen 37077, Germany.
| | - Daniel J Jackson
- Courant Research Centre Geobiology, Georg-August-University of Göttingen, Goldschmidtstr. 3, Göttingen 37077, Germany.
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12
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Hua-Van A, Le Rouzic A, Boutin TS, Filée J, Capy P. The struggle for life of the genome's selfish architects. Biol Direct 2011; 6:19. [PMID: 21414203 PMCID: PMC3072357 DOI: 10.1186/1745-6150-6-19] [Citation(s) in RCA: 180] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Accepted: 03/17/2011] [Indexed: 01/28/2023] Open
Abstract
Transposable elements (TEs) were first discovered more than 50 years ago, but were totally ignored for a long time. Over the last few decades they have gradually attracted increasing interest from research scientists. Initially they were viewed as totally marginal and anecdotic, but TEs have been revealed as potentially harmful parasitic entities, ubiquitous in genomes, and finally as unavoidable actors in the diversity, structure, and evolution of the genome. Since Darwin's theory of evolution, and the progress of molecular biology, transposable elements may be the discovery that has most influenced our vision of (genome) evolution. In this review, we provide a synopsis of what is known about the complex interactions that exist between transposable elements and the host genome. Numerous examples of these interactions are provided, first from the standpoint of the genome, and then from that of the transposable elements. We also explore the evolutionary aspects of TEs in the light of post-Darwinian theories of evolution.
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Affiliation(s)
- Aurélie Hua-Van
- Laboratoire Evolution, Génomes, Spéciation, CNRS UPR9034/Université Paris-Sud, Gif-sur-Yvette, France.
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Gladyshev EA, Arkhipova IR. Genome structure of bdelloid rotifers: shaped by asexuality or desiccation? J Hered 2010; 101 Suppl 1:S85-93. [PMID: 20421328 DOI: 10.1093/jhered/esq008] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Bdelloid rotifers are microscopic invertebrate animals best known for their ancient asexuality and the ability to survive desiccation at any life stage. Both factors are expected to have a profound influence on their genome structure. Recent molecular studies demonstrated that, although the gene-rich regions of bdelloid genomes are organized as colinear pairs of closely related sequences and depleted in repetitive DNA, subtelomeric regions harbor diverse transposable elements and horizontally acquired genes of foreign origin. Although asexuality is expected to result in depletion of deleterious transposons, only desiccation appears to have the power to produce all the uncovered genomic peculiarities. Repair of desiccation-induced DNA damage would require the presence of a homologous template, maintaining colinear pairs in gene-rich regions and selecting against insertion of repetitive DNA that might cause chromosomal rearrangements. Desiccation may also induce a transient state of competence in recovering animals, allowing them to acquire environmental DNA. Even if bdelloids engage in rare or obscure forms of sexual reproduction, all these features could still be present. The relative contribution of asexuality and desiccation to genome organization may be clarified by analyzing whole-genome sequences and comparing foreign gene and transposon content in species which lost the ability to survive desiccation.
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Affiliation(s)
- Eugene A Gladyshev
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA 02543, USA
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14
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Schaack S, Gilbert C, Feschotte C. Promiscuous DNA: horizontal transfer of transposable elements and why it matters for eukaryotic evolution. Trends Ecol Evol 2010; 25:537-46. [PMID: 20591532 DOI: 10.1016/j.tree.2010.06.001] [Citation(s) in RCA: 317] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Revised: 06/03/2010] [Accepted: 06/03/2010] [Indexed: 11/25/2022]
Abstract
Horizontal transfer is the passage of genetic material between genomes by means other than parent-to-offspring inheritance. Although the transfer of genes is thought to be crucial in prokaryotic evolution, few instances of horizontal gene transfer have been reported in multicellular eukaryotes; instead, most cases involve transposable elements. With over 200 cases now documented, it is possible to assess the importance of horizontal transfer for the evolution of transposable elements and their host genomes. We review criteria for detecting horizontal transfers and examine recent examples of the phenomenon, shedding light on its mechanistic underpinnings, including the role of host-parasite interactions. We argue that the introduction of transposable elements by horizontal transfer in eukaryotic genomes has been a major force propelling genomic variation and biological innovation.
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Affiliation(s)
- Sarah Schaack
- Department of Biology, University of Texas at Arlington, Arlington, TX 76019, USA
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Bao W, Kapitonov VV, Jurka J. Ginger DNA transposons in eukaryotes and their evolutionary relationships with long terminal repeat retrotransposons. Mob DNA 2010; 1:3. [PMID: 20226081 PMCID: PMC2836005 DOI: 10.1186/1759-8753-1-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Accepted: 01/25/2010] [Indexed: 12/12/2022] Open
Abstract
Background In eukaryotes, long terminal repeat (LTR) retrotransposons such as Copia, BEL and Gypsy integrate their DNA copies into the host genome using a particular type of DDE transposase called integrase (INT). The Gypsy INT-like transposase is also conserved in the Polinton/Maverick self-synthesizing DNA transposons and in the 'cut and paste' DNA transposons known as TDD-4 and TDD-5. Moreover, it is known that INT is similar to bacterial transposases that belong to the IS3, IS481, IS30 and IS630 families. It has been suggested that LTR retrotransposons evolved from a non-LTR retrotransposon fused with a DNA transposon in early eukaryotes. In this paper we analyze a diverse superfamily of eukaryotic cut and paste DNA transposons coding for INT-like transposase and discuss their evolutionary relationship to LTR retrotransposons. Results A new diverse eukaryotic superfamily of DNA transposons, named Ginger (for 'Gypsy INteGrasE Related') DNA transposons is defined and analyzed. Analogously to the IS3 and IS481 bacterial transposons, the Ginger termini resemble those of the Gypsy LTR retrotransposons. Currently, Ginger transposons can be divided into two distinct groups named Ginger1 and Ginger2/Tdd. Elements from the Ginger1 group are characterized by approximately 40 to 270 base pair (bp) terminal inverted repeats (TIRs), and are flanked by CCGG-specific or CCGT-specific target site duplication (TSD) sequences. The Ginger1-encoded transposases contain an approximate 400 amino acid N-terminal portion sharing high amino acid identity to the entire Gypsy-encoded integrases, including the YPYY motif, zinc finger, DDE domain, and, importantly, the GPY/F motif, a hallmark of Gypsy and endogenous retrovirus (ERV) integrases. Ginger1 transposases also contain additional C-terminal domains: ovarian tumor (OTU)-like protease domain or Ulp1 protease domain. In vertebrate genomes, at least two host genes, which were previously thought to be derived from the Gypsy integrases, apparently have evolved from the Ginger1 transposase genes. We also introduce a second Ginger group, designated Ginger2/Tdd, which includes the previously reported DNA transposon TDD-4. Conclusions The Ginger superfamily represents eukaryotic DNA transposons closely related to LTR retrotransposons. Ginger elements provide new insights into the evolution of transposable elements and certain transposable element (TE)-derived genes.
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Affiliation(s)
- Weidong Bao
- Genetic Information Research Institute, Mountain View, CA, USA.
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