ATP-binding cassette domain of the bacitracin-resistance transporter
The BcrA subfamily represents ABC transporters involved in peptide antibiotic resistance. Bacitracin is a dodecapeptide antibiotic produced by B. licheniformis and B. subtilis. The synthesis of bacitracin is non-ribosomally catalyzed by a multi-enzyme complex BcrABC. Bacitracin has potent antibiotic activity against gram-positive bacteria. The inhibition of peptidoglycan biosynthesis is the best characterized bacterial effect of bacitracin. The bacitracin resistance of B. licheniformis is mediated by the ABC transporter Bcr which is composed of two identical BcrA ATP-binding subunits and one each of the integral membrane proteins, BcrB and BcrC. B. subtilis cells carrying bcr genes on high-copy number plasmids develop collateral detergent sensitivity, a similar phenomenon in human cells with overexpressed multi-drug resistance P-glycoprotein.