Purification and Ligand Binding of EmrR, a Regulator of a Multidrug Transporter

Abstract

ABSTRACTEmrR, the repressor of theemrRABoperon ofEscherichia coli, was purified to 95% homogeneity. EmrR was found to bind putative ligands of the EmrAB pump—2,4-dinitrophenol, carbonyl cyanidem-chlorophenylhydrazone, and carbonyl cyanidep-(trifluoro-methoxy)phenylhydrazone—with affinities in the micromolar range. Equilibrium dialysis experiments suggested one bound ligand per monomer of the dimeric EmrR.