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. 2006 Sep 1;313(5791):1295-8.
doi: 10.1126/science.1131542.

Structural asymmetry of AcrB trimer suggests a peristaltic pump mechanism

Markus A Seeger  1 , André Schiefner, Thomas Eicher, François Verrey, Kay Diederichs, Klaas M Pos
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Structural asymmetry of AcrB trimer suggests a peristaltic pump mechanism

Markus A Seeger et al. Science. .

Abstract

The AcrA/AcrB/TolC complex spans the inner and outer membranes of Escherichia coli and serves as its major drug-resistance pump. Driven by the proton motive force, it mediates the efflux of bile salts, detergents, organic solvents, and many structurally unrelated antibiotics. Here, we report a crystallographic structure of trimeric AcrB determined at 2.9 and 3.0 angstrom resolution in space groups that allow asymmetry of the monomers. This structure reveals three different monomer conformations representing consecutive states in a transport cycle. The structural data imply an alternating access mechanism and a novel peristaltic mode of drug transport by this type of transporter.

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