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Self-synthesizing transposons: unexpected key players in the evolution of viruses and defense systems.
Curr Opin Microbiol. 2016 06; 31:25-33.CO

Abstract

Self-synthesizing transposons are the largest known transposable elements that encode their own DNA polymerases (DNAP). The Polinton/Maverick family of self-synthesizing transposons is widespread in eukaryotes and abundant in the genomes of some protists. In addition to the DNAP and a retrovirus-like integrase, most of the polintons encode homologs of the major and minor jelly-roll capsid proteins, DNA-packaging ATPase and capsid maturation protease. Therefore, polintons are predicted to alternate between the transposon and viral lifestyles although virion formation remains to be demonstrated. Polintons are related to a group of eukaryotic viruses known as virophages that parasitize on giant viruses of the family Mimiviridae and another recently identified putative family of polinton-like viruses (PLV) predicted to lead a similar, dual life style. Comparative genomic analysis of polintons, virophages, PLV and the other viruses with double-stranded (ds)DNA genomes infecting eukaryotes and prokaryotes suggests that the polintons evolved from bacterial tectiviruses and could have been the ancestors of a broad range of eukaryotic viruses including adenoviruses and members of the proposed order 'Megavirales' as well as linear cytoplasmic plasmids. Recently, a group of predicted self-synthesizing transposons was discovered also in prokaryotes. These elements, denoted casposons, encode a DNAP and a homolog of the CRISPR-associated Cas1 endonuclease that has an integrase activity but no capsid proteins. Thus, unlike polintons, casposons appear to be limited to the transposon life style although they could have evolved from viruses. The casposons are thought to have played a pivotal role in the origin of the prokaryotic adaptive immunity, giving rise to the adaptation module of the CRISPR-Cas systems.

Authors+Show Affiliations

Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Department of Microbiology, Institut Pasteur, Paris, France. Electronic address: krupovic@pasteur.fr.National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA. Electronic address: koonin@ncbi.nlm.nih.gov.

Pub Type(s)

Journal Article
Review
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

26836982

Citation

Krupovic, Mart, and Eugene V. Koonin. "Self-synthesizing Transposons: Unexpected Key Players in the Evolution of Viruses and Defense Systems." Current Opinion in Microbiology, vol. 31, 2016, pp. 25-33.
Krupovic M, Koonin EV. Self-synthesizing transposons: unexpected key players in the evolution of viruses and defense systems. Curr Opin Microbiol. 2016;31:25-33.
Krupovic, M., & Koonin, E. V. (2016). Self-synthesizing transposons: unexpected key players in the evolution of viruses and defense systems. Current Opinion in Microbiology, 31, 25-33. https://doi.org/10.1016/j.mib.2016.01.006
Krupovic M, Koonin EV. Self-synthesizing Transposons: Unexpected Key Players in the Evolution of Viruses and Defense Systems. Curr Opin Microbiol. 2016;31:25-33. PubMed PMID: 26836982.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Self-synthesizing transposons: unexpected key players in the evolution of viruses and defense systems. AU - Krupovic,Mart, AU - Koonin,Eugene V, Y1 - 2016/02/01/ PY - 2015/12/17/received PY - 2016/01/13/revised PY - 2016/01/14/accepted PY - 2016/2/3/entrez PY - 2016/2/3/pubmed PY - 2017/11/29/medline SP - 25 EP - 33 JF - Current opinion in microbiology JO - Curr Opin Microbiol VL - 31 N2 - Self-synthesizing transposons are the largest known transposable elements that encode their own DNA polymerases (DNAP). The Polinton/Maverick family of self-synthesizing transposons is widespread in eukaryotes and abundant in the genomes of some protists. In addition to the DNAP and a retrovirus-like integrase, most of the polintons encode homologs of the major and minor jelly-roll capsid proteins, DNA-packaging ATPase and capsid maturation protease. Therefore, polintons are predicted to alternate between the transposon and viral lifestyles although virion formation remains to be demonstrated. Polintons are related to a group of eukaryotic viruses known as virophages that parasitize on giant viruses of the family Mimiviridae and another recently identified putative family of polinton-like viruses (PLV) predicted to lead a similar, dual life style. Comparative genomic analysis of polintons, virophages, PLV and the other viruses with double-stranded (ds)DNA genomes infecting eukaryotes and prokaryotes suggests that the polintons evolved from bacterial tectiviruses and could have been the ancestors of a broad range of eukaryotic viruses including adenoviruses and members of the proposed order 'Megavirales' as well as linear cytoplasmic plasmids. Recently, a group of predicted self-synthesizing transposons was discovered also in prokaryotes. These elements, denoted casposons, encode a DNAP and a homolog of the CRISPR-associated Cas1 endonuclease that has an integrase activity but no capsid proteins. Thus, unlike polintons, casposons appear to be limited to the transposon life style although they could have evolved from viruses. The casposons are thought to have played a pivotal role in the origin of the prokaryotic adaptive immunity, giving rise to the adaptation module of the CRISPR-Cas systems. SN - 1879-0364 UR - https://www.unboundmedicine.com/medline/citation/26836982/Self_synthesizing_transposons:_unexpected_key_players_in_the_evolution_of_viruses_and_defense_systems_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1369-5274(16)00008-4 DB - PRIME DP - Unbound Medicine ER -