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1iwg, resolution 3.50Å ()
Resources: FirstGlance, OCA, RCSB, PDBsum
Coordinates: save as pdb, mmCIF, xml

Crystal structure of Bacterial Multidrug Efflux transporter AcrB

Publication Abstract from PubMed

AcrB is a major multidrug exporter in Escherichia coli. It cooperates with a membrane fusion protein, AcrA, and an outer membrane channel, TolC. We have determined the crystal structure of AcrB at 3.5 A resolution. Three AcrB protomers are organized as a homotrimer in the shape of a jellyfish. Each protomer is composed of a transmembrane region 50 A thick and a 70 A protruding headpiece. The top of the headpiece opens like a funnel, where TolC might directly dock into AcrB. A pore formed by three alpha-helices connects the funnel with a central cavity located at the bottom of the headpiece. The cavity has three vestibules at the side of the headpiece which lead into the periplasm. In the transmembrane region, each protomer has twelve transmembrane alpha-helices. The structure implies that substrates translocated from the cell interior through the transmembrane region and from the periplasm through the vestibules are collected in the central cavity and then actively transported through the pore into the TolC tunnel.

Crystal structure of bacterial multidrug efflux transporter AcrB., Murakami S, Nakashima R, Yamashita E, Yamaguchi A, Nature. 2002 Oct 10;419(6907):587-93. PMID:12374972

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

About this Structure

1iwg is a 1 chain structure with sequence from Escherichia coli. The November 2007 RCSB PDB Molecule of the Month feature on Multidrug Resistance Transporters by David S. Goodsell is 10.2210/rcsb_pdb/mom_2007_11. Full crystallographic information is available from OCA.


  • Murakami S, Nakashima R, Yamashita E, Yamaguchi A. Crystal structure of bacterial multidrug efflux transporter AcrB. Nature. 2002 Oct 10;419(6907):587-93. PMID:12374972 doi:10.1038/nature01050

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