Drug-bound and -free outward-facing structures of a multidrug ABC exporter point to a swing mechanism

Chaptal, v.; Zampieri, V.; Wiseman, B.; Orelle, C.; Martin, J.; Nguyen, K.-A.; Magnard, S.; Gobet, A.; Di cesare, M.; Javed, W.; Kilburg, A.; Peuchmaur, M.; Marcoux, J.; Hogbom, M.; Jault, J.-M.; Boumendjel, A.; Falson, P. G.

doi:10.1101/2021.03.12.435132

bioRxiv · 10.1101/2021.03.12.435132

Drug-bound and -free outward-facing structures of a multidrug ABC exporter point to a swing mechanism

Chaptal, v.·Zampieri, V.·Wiseman, B.·Orelle, C.·Martin, J.·Nguyen, K.-A.·Magnard, S.·Gobet, A.·Di cesare, M.·Javed, W.·Kilburg, A.·Peuchmaur, M.·Marcoux, J.·Hogbom, M.·Jault, J.-M.·Boumendjel, A.·Falson, P. G.

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Abstract

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 two ATP-Mg2+-bound outward-facing (OF) conformations of the Bacillus subtilis (homodimeric) BmrA, one by X-ray crystallography without drug, and another by single-particle cryo-EM with rhodamine 6G (R6G). 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. R6G induces a rearrangement of TM1-2, highlighting a flexibility that was confirmed by H/D exchange and molecular dynamics simulations. The latter also shows a fast post-release occlusion of the cavity driven by hydrophobicity. Altogether, these data support a new swing mechanism for drug transport.

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Chaptal, v., Zampieri, V., Wiseman, B., Orelle, C., Martin, J., Nguyen, K.-A., Magnard, S., Gobet, A., Di cesare, M., Javed, W., Kilburg, A., Peuchmaur, M., Marcoux, J., Hogbom, M., Jault, J.-M., Boumendjel, A., Falson, P. G.. 2021-03-12. Drug-bound and -free outward-facing structures of a multidrug ABC exporter point to a swing mechanism. https://doi.org/10.1101/2021.03.12.435132

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