Allosteric drug transport mechanism of multidrug transporter AcrB

  • Gram-negative bacteria maintain an intrinsic resistance mechanism against entry of noxious compounds by utilizing highly efficient efflux pumps. The E. coli AcrAB-TolC drug efflux pump contains the inner membrane H+/drug antiporter AcrB comprising three functionally interdependent protomers, cycling consecutively through the loose (L), tight (T) and open (O) state during cooperative catalysis. Here, we present 13 X-ray structures of AcrB in intermediate states of the transport cycle. Structure-based mutational analysis combined with drug susceptibility assays indicate that drugs are guided through dedicated transport channels toward the drug binding pockets. A co-structure obtained in the combined presence of erythromycin, linezolid, oxacillin and fusidic acid shows binding of fusidic acid deeply inside the T protomer transmembrane domain. Thiol cross-link substrate protection assays indicate that this transmembrane domain-binding site can also accommodate oxacillin or novobiocin but not erythromycin or linezolid. AcrB-mediated drug transport is suggested to be allosterically modulated in presence of multiple drugs.
Author:Heng Keat Tam, Wuen Ee Foong, Christine Oswald, Andrea Herrmann, Hui Zeng, Klaas Martinus PosORCiD
Parent Title (English):Nature Communications
Publisher:Nature Publishing Group UK
Place of publication:[London]
Document Type:Article
Date of Publication (online):2021/06/29
Date of first Publication:2021/06/29
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2022/06/01
Tag:Antimicrobial resistance; Bacterial structural biology; Enzyme mechanisms; X-ray crystallography
Issue:art. 3889
Page Number:10
First Page:1
Last Page:10
This work was supported by the German Research Foundation (SFB 807, Transport and Communication across Biological Membranes), the DFG-EXC115 (Cluster of Excellence Frankfurt—Macromolecular Complexes), and the German-Israeli Foundation (Grant No. I-1202-248.9/2012). The research leading to these results was conducted as part of the Translocation consortium ( and has received support from the Innovative Medicines Joint Undertaking under Grant Agreement n°115525, resources which are composed of financial contribution from the European Union seventh framework program (FP7/2007-2013). The synchrotron trips to SOLEIL were partly supported by iNEXT, under PID: 7108, funded by the Horizon 2020 programme of the European Union.
Open Access funding enabled and organized by Projekt DEAL.
Institutes:Biochemie, Chemie und Pharmazie
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 54 Chemie / 540 Chemie und zugeordnete Wissenschaften
5 Naturwissenschaften und Mathematik / 57 Biowissenschaften; Biologie / 570 Biowissenschaften; Biologie
Licence (German):License LogoCreative Commons - Namensnennung 4.0