Nucleotide sequence at the insertion sites of a kanamycin transposon.

Abstract

THE TRANSPOSON Tn903 carrying a gene for kanamycin resistance, is 3,100 base pairs in size and contains an inverted repeat sequence of 1,050 base pairs at both ends1–4. We report here the generation of a 9-base pair repeated sequence at the insertion site of Tn903. Tn903 can be transposed to at least nine different sites on the coliphage fd DNA1,2. We have also transposed Tn903 to three sites on small colicin E1 plasmid (ColE1) derivatives of about 1,600 base pairs. The presence of these many insertion sites on small recipient DNA molecules implies that no specific sequence is involved in the target sites on the recipient. To investigate the mechanism of transposition of Tn903 at the molecular level, we have now analysed three independent insertions of Tn903 on the small ColE1 DNA molecules. The nucleotide sequences of the three target sites and of the corresponding junctions between Tn903 and the small ColE1 have been determined.