Molecular characterization of mariner-like elements in Bruchus pisorum and Bruchus rufimanus (Coleoptera: Bruchidae)

Abstract

Mariner-like elements (MLEs) are Class-II transposons that are widely present in diverse organisms and encode a D, D34D transposase motif. MLE sequences from two coleopteran species, Bruchus pisorum and B. rufimanus were obtained using the terminal-inverted repeats (TIRs) of mariner elements belonging to the mauritiana subfamily as primer. The characterized elements were between 1073 and 1302 bp in length and are likely to be inactive, based on the presence of multiple stop codons and/or frameshifts. A single consensus of MLE was detected in B. pisorum and was named Bpmar1. This element exhibited several conserved amino acid blocks as well as the specific D, D(34)D signature. As for B. rufimanus, two MLE consensuses, designated Brmar1 and Brmar2, were isolated, both containing deletions overlapping the internal region of the transposase. Structural and phylogenetic analysis of these sequences suggested a relatively recent origin of Bpmar1 versus a more ancient invasion of Brmar1 and Brmar2 in their respective host genomes. Given that MLEs are potential mediators of insect resistance and have been used as vectors to transfer genes into host genomes, the MLEs characterized in this study will have valuable implications for selecting appropriate transposable elements in transgenesis.