IDENTIFICATION OF AN ABC TRANSPORTER GENE THAT EXHIBITS MESSENGER-RNALEVEL OVEREXPRESSION IN FLUOROQUINOLONE-RESISTANT MYCOBACTERIUM-SMEGMATIS

We describe here the PCR amplification of a DNA fragment (mtp1) from M ycobacterium smegmatis using primers derived from consensus sequences of the ABC family of transporters. The fragment encodes amino acid seq uences that exhibited significant homology with different ABC transpor ters. Amino acid sequence alignment of the full length gene with other transporters identified the ABC protein as the B-subunit of the phosp hate specific transporter. Strikingly, a M. smegmatis colony which exh ibited a high level of ciprofloxacin resistance showed mRNA level over expression of mtp1. Thus this is the first report in any prokaryote in dicating differential expression of an ABC transporter in a fluoroquin olone resistant colony. (C) 1998 Federation of European Biochemical.