GENES FOR GENTAMICIN-(3)-N-ACETYLTRANSFERASES-III AND GENTAMICIN-(3)-N-ACETYLTRANSFERASE-IV .1. NUCLEOTIDE-SEQUENCE OF THE AAC(3)-IV GENE AND POSSIBLE INVOLVEMENT OF AN IS140 ELEMENT IN ITS EXPRESSION

Genes [from Escherichia coli] for gentamicin-3-acetyltransferases [ACC(3)] of types III and IV were cloned from various R-plasmids. In 2 R-plasmids, pWP14a (AAC(3)-III) and pWP7b [AAC(3)-IV], resistance genes were found directly adjacent to a single copy of an IS [insertion sequence] element, IS140. Nucleotide sequence determination of the AAC(3)-IV gene from plasmid pWP7b and of part of IS140 from 3 different sources suggested that the -35 region of the AAC(3)-IV promoter was part of the IS element. A similarly built-up promoter was found in pWP14a. A hygromycin B phosphotransferase was expressed from a locus neighboring the AAC(3)-IV gene in pWP7b which was under the control of the same promoter. In 2 other R-plasmids, pWP113a and pWb116a, the AAC(3)-III gene was found in different genetic environments, namely close to [transposon] Tn3-like structures.