Evolutionary study of the 412/mdg1 lineage of the Ty3/gypsy group of LTR retrotransposons in Diptera

Abstract

LTR-retrotransposons are structurally similar to retroviruses, as they possess the enzymes reverse transcriptase, Ribonuclease H, integrase, proteinase, and the gag gene and are flanked by long terminal repeats (LTRs). The 412/mdg1 lineage, belonging to the Ty3/Gypsy group, consists of the TEs 412, mdg1, stalker, pilgrim, and blood. The 412/mdg1 lineage is distinguished from the others in the gypsy group in that it has small ORFs at the beginning of the TE and is highly similar to the pol ORF among the TEs that make up the lineage. In this study, our aim was to elucidate the evolutionary history of the 412/mdg1 lineage in the 127 dipteran genomes available to date, and the characteristics of the sequences in each genome. We used the canonical TE 412 probe described in Drosophila melanogaster as the query. We found sequences homologous to the 412/mdg1 lineage restricted to the suborder Brachycera. These sequences are widely distributed in drosophilids but are also present in other groups of flies. We note the presence of the 412/mg1 lineage in tsetse flies (Glossina). Furthermore, our results showed an elaborate evolutionary history for the pol ORF in the 412/mdg1 lineage of the LTR-Retrotransposon.