Purification, crystallization and preliminary diffraction studies of AcrB, an inner-membrane multi-drug efflux protein

Resistance of pathogens to antibiotics is often dependent on multidrug export proteins that reside in the inner membrane of bacteria. This work describes the expression, purification, crystallization and preliminary crystallographic analysis of AcrB of Escherichia coli. Together with AcrA and TolC, AcrB forms a proton motive force dependent efflux pump of the resistance-nodulation-cell division (RND) transporter superfamily and is responsible for resistance towards many common antibiotics such as ciprofloxacin and novobiocin. AcrB crystallizes in space group R32, with unit-cell parameters a = b = 143, c = 513 Angstrom; the crystals diffract to 3.0 Angstrom resolution.