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Structures of Gate Loop Variants of the AcrB Drug Efflux Pump Bound by Erythromycin Substrate

DOI: 10.1371/journal.pone.0159154 DOI Help

Authors: Abdessamad Ababou (University of Cambridge) , Vassilis Koronakis (University of Cambridge)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Plos One , VOL 11

State: Published (Approved)
Published: July 2016

Open Access Open Access

Abstract: Gram-negative bacteria such as E. coli use tripartite efflux pumps such as AcrAB-TolC to expel antibiotics and noxious compounds. A key feature of the inner membrane transporter component, AcrB, is a short stretch of residues known as the gate/switch loop that divides the proximal and distal substrate binding pockets. Amino acid substitutions of the gate loop are known to decrease antibiotic resistance conferred by AcrB. Here we present two new AcrB gate loop variants, the first stripped of its bulky side chains, and a second in which the gate loop is removed entirely. By determining the crystal structures of the variant AcrB proteins in the presence and absence of erythromycin and assessing their ability to confer erythromycin tolerance, we demonstrate that the gate loop is important for AcrB export activity but is not required for erythromycin binding.

Journal Keywords: MULTIDRUG EFFLUX; BINDING POCKET; SWITCH-LOOP; TRANSPORTER; MECHANISM; RESISTANCE; REVEAL; SYSTEM; PHENIX

Subject Areas: Biology and Bio-materials, Chemistry, Medicine


Instruments: I02-Macromolecular Crystallography , I03-Macromolecular Crystallography , I04-Macromolecular Crystallography

Other Facilities: ID23-1 at the European Synchrotron Radiation Facility (Grenoble, France). 100 K on beam line PXIII at Swiss Light Source (SLS) at the Paul Scherrer Institut (Villigen PSI, Switzerland)

Added On: 08/08/2016 15:57

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