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Article Dans Une Revue Science Advances Année : 2022

Substrate-bound and substrate-free outward-facing structures of a multidrug ABC exporter

Julien Marcoux
Guy Schoehn

Résumé

Multidrug ABC transporters translocate drugs across membranes by a mechanism for which the molecular features of drug release are so far unknown. Here, we resolved three ATP-Mg$^{2+}$–bound outward-facing conformations of the $Bacillus\ subtilis$ (homodimeric) BmrA by x-ray crystallography and single-particle cryo–electron microscopy (EM) in detergent solution, one of them with rhodamine 6G (R6G), a substrate exported by BmrA when overexpressed in $B.\ subtilis$ . Two R6G molecules bind to the drug-binding cavity at the level of the outer leaflet, between transmembrane (TM) helices 1–2 of one monomer and TM5′–6′ of the other. They induce a rearrangement of TM1–2, highlighting a local flexibility that we confirmed by hydrogen/deuterium exchange and molecular dynamics simulations. In the absence of R6G, simulations show a fast postrelease occlusion of the cavity driven by hydrophobicity, while when present, R6G can move within the cavity, maintaining it open.
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Dates et versions

hal-03552930 , version 1 (07-07-2022)
hal-03552930 , version 2 (12-11-2022)

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Paternité - Pas d'utilisation commerciale

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Vincent Chaptal, Veronica Zampieri, Benjamin Wiseman, Cédric Orelle, Juliette Martin, et al.. Substrate-bound and substrate-free outward-facing structures of a multidrug ABC exporter. Science Advances , 2022, 8 (4), pp.eabg9215. ⟨10.1126/sciadv.abg9215⟩. ⟨hal-03552930v1⟩
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