[Molecular analysis of a copy of the novel mobile element Burdock and the region of its insertion into the cut locus of Drosophila melanogaster].

Molecular analysis of a copy of the novel mobile element burdock and its insertion region into the cut locus of Drosophila was performed. The burdock was shown to be a retrotransposon containing a single open reading frame (ORF). It does not contain domens coding for protease, RNAse H, reverse transcriptase, and integrase, which are required for transposition. However, multiple insertions of this copy of the mobile element into a definite region of the cut locus (hot site) were observed earlier. The polypeptide encoded by the burdock ORF contains two successive regions homologous to the proteins encoded by the ORF1 and ORF2 of the gypsy retrotransposon in N and C regions, respectively. The burdock insertion into this region of the cut locus interrupts its ORF, since the mobile element is transcribed in the opposite direction compared with the transcription in the locus. This is presumed to account for the arising of a lethal mutation. The hot site of this element integration into the locus corresponds to the recognition site of Drosophila topoisomerase II.