CHARACTERIZATION OF AARA, A PLEIOTROPIC NEGATIVE REGULATOR OF THE 2'-N-ACETYLTRANSFERASE IN PROVIDENCIA-STUARTII

We have utilized transposon mutagenesis to obtain insertional mutation s in Providencia stuartii that activate the chromosomal aac(2')-la gen e. Two closely linked mini-Tn5Cm insertions were obtained in a locus d esignated aarA, and a single insertion was obtained in a separate locu s, aarC. Nucleotide sequence analysis, complementation studies, and lo calization of the sites of mini-Tn5Cm insertion have allowed the ident ification of the aarA coding region. The deduced AarA protein had a mo lecular mass of 31,086 kDa and displayed characteristics of an integra l membrane protein. A strain deleted for the aarA gene by allelic exch ange showed at least a fourfold increase in the accumulation of aac(2' )-la mRNA and an eightfold increase in aminoglycoside resistance. Muta tions in aarA were pleiotrophic and also resulted in loss of pigmentat ion and a deficiency in cell separation during division.