β-lactamase-specifying plasmids isolated from Neisseria gonorrhoeae have retained and intact right part of a Tn3-like transposon

Abstract

In 3 β-lactamase-producing strains of N. gonorrhoeae, ampicillin resistance is due to the presence of a 7.4-kilobase plasmid. Heteroduplex analysis has shown that the R plasmid contains a 1.6-kilobase segment homologous to the right part (the region coding for the β-lactamase) of the Tn3-like transposon Tn2301. The 1.6-kilobase DNA segment is not transposable, but it can give rise to a functional transposon when linked to the left part of Tn2301. This provides strong evidence that the R plasmids of N. gonorrhoeae are deletion derivatives of a plasmid that contained an entire Tn3-like transposon.