title: Evolution of adaptive immunity from transposable elements combined with innate immune systems.
abstract: Adaptive immune systems in prokaryotes and animals give rise to long-term memory through modification of specific genomic loci, such as by insertion of foreign (viral or plasmid) DNA fragments into clustered regularly interspaced short palindromic repeat (CRISPR) loci in prokaryotes and by V(D)J recombination of immunoglobulin genes in vertebrates. Strikingly, recombinases derived from unrelated mobile genetic elements have essential roles in both prokaryotic and vertebrate adaptive immune systems. Mobile elements, which are ubiquitous in cellular life forms, provide the only known, naturally evolved tools for genome engineering that are successfully adopted by both innate immune systems and genome-editing technologies. In this Opinion article, we present a general scenario for the origin of adaptive immunity from mobile elements and innate immune systems.
authors.affiliation: National Center for Biotechnology Information, National Library of Medicine, Bethesda, Maryland 20894, USA.
authors.forename: Eugene V
authors.initials: EV
authors.lastname: Koonin
authors.affiliation: Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, 25 rue du Docteur Roux, 75015 Paris, France.
authors.forename: Mart
authors.initials: M
authors.lastname: Krupovic
mesh_terms: D056704:Adaptive Immunity; D000818:Animals; D001105:Archaea / Q000235:genetics / Q000276:immunology; D001419:Bacteria / Q000235:genetics / Q000276:immunology; D001483:Base Sequence; D005075:Biological Evolution; D004251:DNA Transposable Elements / Q000276:immunology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000276:immunology*; D006801:Humans; D007113:Immunity, Innate; D007136:Immunoglobulins / Q000235:genetics*; D008969:Molecular Sequence Data; D060152:V(D)J Recombination / Q000235:genetics
chemical_list: C577974:CasB protein, E coli; D004251:DNA Transposable Elements; D029968:Escherichia coli Proteins; D007136:Immunoglobulins