AcrA, AcrB, and TolC of Escherichia coli Form a Stable Intermembrane Multidrug Efflux Complex

• Published in: The Journal of biological chemistry Vol. 279; no. 31; pp. 32116 - 32124
• Main Authors: Tikhonova, Elena B, Zgurskaya, Helen I
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 30-07-2004
• Subjects: Carrier Proteins - metabolism; Cell Division; Cell Membrane - metabolism; Centrifugation, Density Gradient; Cross-Linking Reagents - pharmacology; Drug Resistance, Multiple; Electrophoresis, Polyacrylamide Gel; Escherichia coli; Escherichia coli - metabolism; Escherichia coli Proteins - metabolism; Lipoproteins - metabolism; Membrane Proteins - metabolism; Membrane Transport Proteins; Multidrug Resistance-Associated Proteins; Nuclear Proteins - metabolism; Plasmids - metabolism; Protein Structure, Tertiary; Sucrose - pharmacology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M402230200

Many transporters of Gram-negative bacteria involved in the extracellular secretion of proteins and the efflux of toxic molecules
operate by forming intermembrane complexes. These complexes are proposed to span both inner and outer membranes and create
a bridge across the periplasm. In this study, we analyzed interactions between the inner and outer membrane components of
the tri-partite multidrug efflux pump AcrAB-TolC from Escherichia coli . We found that, once assembled, the intermembrane AcrAB-TolC complex is stable during the separation of the inner and outer
membranes and subsequent purification. All three components of the complex co-purify when the affinity tag is attached to
either of the proteins suggesting bi-partite interactions between AcrA, AcrB, and TolC. We show that antibiotics, the substrates
of AcrAB-TolC, stabilize interactions within the complex. However, the formation of the AcrAB-TolC complex does not require
an input of energy.