Reconstruction of an Active Integron Recombination Site after Integration of a Gene Cassette at a Secondary Site

As the site of insertion of the aadB gene cassette on pRAY, from a clinical isolate of Acinetobacter, is almost identical to the preferred site on integrons, the composite 59-base element (59-BE) associated with this cassette is potentially recombinationally active. By using a conduction assay to quantitate site activity, the 59-BE was recognized by integrase with high frequency, indicating that the composite site is recombinationally active.