[Characteristics of transposition of Tn7-like elements determining resistance to trimethoprim and streptomycin].

The transposing elements Tn7, Tn1824, controlling the resistance to trimethoprim and Tn1925, Tn1826, carrying the streptothricin resistance genes were classified as a new transposon family on the basis of their physical structure. The comparative genetic analysis of the frequency, specificity and insertion orientation in different replicons, obtained in independent research systems in this study, demonstrated the identity of transposition characteristics of the transposons. The latter makes it possible to classify them as an independent transposon family. The peculiar feature of the Tn7-like elements family is their RecA-dependent transposition into the chromosome of Escherichia coli stimulated by bacteriophage Plkc transduction of the transposons.