Purification and ligand binding of EmrR, a regulator of a multidrug transporter

Abstract

EmrR, the repressor of the emrRAB operon of Escherichia coli, was purified to 95% homogeneity. EmrR was found to bind putative ligands of the EmrAB pump-2,4-dinitrophenol, carbonyl cyanide m-chlorophenylhydrazone, and carbonyl cyanide p-(trifluoro-methoxy)phenylhydrazone - with affinities in the micromolar range. Equilibrium dialysis experiments suggested one bound ligand per monomer of the dimeric EmrR.