Identification and evolutionary history of the DD41D transposons in insects
2016
Zhang, H.H., Jiujiang University, Jiujiang, China | Shen, Y.H., Southwest University, Chongqing, China | Xiong, X.M., Jiujiang University, Jiujiang, China | Han, M.J., Southwest University, Chongqing, China | Zhang, X.G., Jiujiang University, Jiujiang, China
The rosa monophyletic group of transposons is a group of transposable element with characteristics of encoding a DD41D motif in the catalytic domain. However, biology and evolutionary history of this monophyletic group are still poorly understood. In this study, we report the first description for the presence of a rosa transposon in the silkworm Bombyx mori. Further analyses confirmed that this element in the silkworm genome had recently amplified and might still be capable of transposition. In addition, we present evidence, based on searches of publicly available insect genomes, that a new clade of the rosa monophyletic group was identified. Interestingly, analysis of their three dimensional structures suggested that these proteins showed highly similar protein structures with that of the Mos1 transposase. These results provided useful insights into the functionality of these transposases and their structural and functional deviations from other transposases in the Tc1/mariner superfamily. Meanwhile, sequence and phylogenetic analysis confirmed that DD41D and maT elements might represent another independent large group of the Tc1/mariner superfamily. Importantly, the result of the comparison of terminal inverted repeats (TIRs) validated that DD41D and maT elements almost had identical consensus terminal sequences (50-CAGGGTGNS NCA-3'), implying they might have similar cleavage sites or patterns during the process of their transposition. In a word, this study will enrich and expand our knowledge of the Tc1/mariner superfamily.
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