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Three‐dimensional structure of the bacterial multidrug transporter EmrE shows it is an asymmetric homodimer
Author(s) -
UbarretxenaBelandia Iban,
Baldwin Joyce M.,
Schuldiner Shimon,
Tate Christopher G.
Publication year - 2003
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/cdg611
Subject(s) - antiporters , biology , dimer , cryo electron microscopy , lipid bilayer , transmembrane protein , transporter , atp binding cassette transporter , biophysics , electron crystallography , transmembrane domain , protein structure , escherichia coli , crystallography , biochemistry , amino acid , membrane , chemistry , receptor , gene , electron diffraction , physics , organic chemistry , diffraction , optics
The small multidrug resistance family of transporters is widespread in bacteria and is responsible for bacterial resistance to toxic aromatic cations by proton‐linked efflux. We have determined the three‐dimensional (3D) structure of the Escherichia coli multidrug transporter EmrE by electron cryomicroscopy of 2D crystals, including data to 7.0 Å resolution. The structure of EmrE consists of a bundle of eight transmembrane α‐helices with one substrate molecule bound near the centre. The substrate binding chamber is formed from six helices and is accessible both from the aqueous phase and laterally from the lipid bilayer. The most remarkable feature of the structure of EmrE is that it is an asymmetric homodimer. The possible arrangement of the two polypeptides in the EmrE dimer is discussed based on the 3D density map.