3D cryo-electron reconstruction of BmrA, a bacterial multidrug ABC transporter in an inward-facing conformation and in a lipidic environment.

Abstract : ABC (ATP-binding cassette) membrane exporters are efflux transporters of a wide diversity of molecule across the membrane at the expense of ATP. A key issue regarding their catalytic cycle is whether or not their nucleotide-binding domains (NBDs) are physically disengaged in the resting state. To settle this controversy, we obtained structural data on BmrA, a bacterial multidrug homodimeric ABC transporter, in a membrane-embedded state. BmrA in the apostate was reconstituted in lipid bilayers forming a mixture of ring-shaped structures of 24 or 39 homodimers. Three-dimensional models of the ring-shaped structures of 24 or 39 homodimers were calculated at 2.3 nm and 2.5 nm resolution from cryo-electron microscopy, respectively. In these structures, BmrA adopts an inward-facing open conformation similar to that found in mouse P-glycoprotein structure with the NBDs separated by 3 nm. Both lipidic leaflets delimiting the transmembrane domains of BmrA were clearly resolved. In planar membrane sheets, the NBDs were even more separated. BmrA in an ATP-bound conformation was determined from two-dimensional crystals grown in the presence of ATP and vanadate. A projection map calculated at 1.6 nm resolution shows an open outward-facing conformation. Overall, the data are consistent with a mechanism of drug transport involving large conformational changes of BmrA and show that a bacterial ABC exporter can adopt at least two open inward conformations in lipid membrane.
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Article dans une revue
Journal of Molecular Biology, Elsevier, 2014, 426 (10), pp.2059-69
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http://hal.univ-grenoble-alpes.fr/hal-01130596
Contributeur : Frank Thomas <>
Soumis le : jeudi 12 mars 2015 - 09:21:45
Dernière modification le : jeudi 13 septembre 2018 - 15:24:07

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  • HAL Id : hal-01130596, version 1
  • PUBMED : 24630999

Citation

Pierre Frederic Fribourg, Mohamed Chami, Carlos Oscar S Sorzano, Francesca Gubellini, Roberto Marabini, et al.. 3D cryo-electron reconstruction of BmrA, a bacterial multidrug ABC transporter in an inward-facing conformation and in a lipidic environment.. Journal of Molecular Biology, Elsevier, 2014, 426 (10), pp.2059-69. 〈hal-01130596〉

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