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Updated: Jul 13, 2026

In vitro Investigation of the MexAB Efflux Pump From Pseudomonas aeruginosa
Published on: February 17, 2014
Crystal structure of bacterial multidrug efflux transporter AcrB
Satoshi Murakami1, Ryosuke Nakashima, Eiki Yamashita
1Department of Cell Membrane Biology, Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan.
The crystal structure of AcrB, a multidrug exporter in Escherichia coli, reveals a unique homotrimer assembly. This structure clarifies how AcrB collaborates with AcrA and TolC to expel drugs from bacterial cells.
Area of Science:
- Structural Biology
- Microbiology
- Biochemistry
Background:
- AcrB is a crucial multidrug exporter in Escherichia coli, essential for bacterial survival against toxic compounds.
- AcrB functions as part of a tripartite complex with AcrA (membrane fusion protein) and TolC (outer membrane channel).
Purpose of the Study:
- To determine the high-resolution crystal structure of the AcrB multidrug exporter.
- To elucidate the structural basis for AcrB's function in multidrug efflux.
Main Methods:
- X-ray crystallography was employed to determine the crystal structure of AcrB.
- The structure was resolved at a resolution of 3.5 Angstroms.
Main Results:
- The crystal structure revealed AcrB organized as a homotrimer, resembling a jellyfish.
- Each protomer consists of a transmembrane region and a protruding headpiece with a funnel-like opening.
- A pore connects the funnel to a central cavity with vestibules leading to the periplasm, facilitating substrate collection and transport.
Conclusions:
- The determined structure provides a detailed molecular model for AcrB's drug efflux mechanism.
- It suggests a pathway for substrate translocation from the cell interior and periplasm to the central cavity, and subsequent expulsion via the TolC channel.
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