1. Perturbed structural dynamics underlie inhibition and altered specificity of the multidrug efflux pump AcrB
- Author
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Chiara Fais, Elizabeth M Grimsey, Giuliano Malloci, Zainab Ahdash, Paolo Ruggerone, Paula J. Booth, Andy M. Lau, Albert Konijnenberg, Ricci, Jack W Stone, Kan Xw, Piddock Ljv, Eamonn Reading, Attilio Vittorio Vargiu, Anargyros Politis, and Heather E. Findlay
- Subjects
0303 health sciences ,Drug export ,biology ,030306 microbiology ,medicine.drug_class ,Chemistry ,Antibiotics ,Dynamics (mechanics) ,biology.organism_classification ,Transport Pathway ,03 medical and health sciences ,medicine ,Biophysics ,Hydrogen–deuterium exchange ,Efflux ,Function (biology) ,Bacteria ,030304 developmental biology - Abstract
Resistance-nodulation-division (RND) efflux pumps play a key role in inherent and evolved multidrug-resistance (MDR) in bacteria. AcrB is the prototypical member of the RND family and acts to recognise and export a wide range of chemically distinct molecules out of bacteria, conferring resistance to a variety of antibiotics. Although high resolution structures exist for AcrB, its conformational fluctuations and their putative role in function are largely unknown, preventing a complete mechanistic understanding of efflux and inhibition. Here, we determine these structural dynamics in the presence of AcrB substrates using hydrogen/deuterium exchange mass spectrometry, complemented by molecular modelling, drug binding and bacterial susceptibility studies. We show that the well-studied efflux pump inhibitor phenylalanine-arginine-β-naphthylamide (PAβN) potentiates antibiotic activity by restraining drug-binding pocket dynamics, rather than preventing antibiotic binding. We also reveal that a drug-binding pocket substitution discovered within an MDR clinical isolate, AcrBG288D, modifies the plasticity of the transport pathway, which could explain its altered substrate specificity. Our results provide molecular insight into drug export and inhibition of a major MDR-conferring efflux pump and the important directive role of its dynamics.
- Published
- 2020
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