Prokaryotic and Eukaryotic Horizontal Transfer of Sailor (DD82E), a New Superfamily of IS630-Tc1-Mariner DNA Transposons

Abstract

Here, a new superfamily of <i>IS630-Tc1-mariner</i> (<i>ITm</i>) DNA transposons, termed Sailor, is identified, that is characterized by a DD82E catalytic domain and is distinct from all previously known superfamilies of the <i>ITm</i> group. Phylogenetic analyses revealed that <i>Sailor</i> forms a monophyletic clade with a more intimate link to the clades of <i>Tc1/mariner</i> and <i>DD34E/Gambol</i>. <i>Sailor</i> was detected in both prokaryotes and eukaryotes and invaded a total of 256 species across six kingdoms. <i>Sailor</i> is present in nine species of bacteria, two species of plantae, four species of protozoa, 23 species of Chromista, 12 species of Fungi and 206 species of animals. Moreover, <i>Sailor</i> is extensively distributed in invertebrates (a total of 206 species from six phyla) but is absent in vertebrates. <i>Sailor</i> transposons are 1.38-6.98 kb in total length and encoded transposases of ~676 aa flanked by TIRs with lengths between 18, 1362 and 4 bp (TATA) target-site duplications. Furthermore, our analysis provided strong evidence of <i>Sailor</i> transmissions from prokaryotes to eukaryotes and internal transmissions in both. These data update the classification of the <i>ITm</i> group and will contribute to the understanding of the evolution of <i>ITm</i> transposons and that of their hosts.