Integration specificity of an artificial kanamycin transposon constructed by the in vitro insertion of an internal Tn5 fragment into IS2.

IS2 has been marked genetically by the in vitro insertion into its HindIII site of a 3.3 Kb HindIII fragment of Tn5 conferring resistance to kanamycin. The transposition of the IS2::Km, thus obtained, to lambda has been found and insertion sites were characterised. Each of ten independent IS2::Km insertions were found at the same site at 61.2% of the lambda map, always in the same orientation (orientation II relative to the xis gene). The integration sites of IS2::Km in five of the kanamycin-transducing phages were determined by DNA sequence analysis, and were found to be identical at the nucleotide level. Further transposition of IS2::Km from lambda to the bacterial chromosome was demonstrated.