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 int egrons, the composite 59-base element (59-BE) associated with this cassette is potentially recombinationally active. By using a conduction assay to qu antitate site activity, the 59-BE was recognized by integrase with high fre quency, indicating that the composite site is recombinationally active.