6Q4N image
Entry Detail
PDB ID:
6Q4N
Title:
Fusidic acid bound AcrB_V340A
Biological Source:
PDB Version:
Deposition Date:
2018-12-06
Release Date:
2019-11-13
Method Details:
Experimental Method:
Resolution:
2.80 Å
R-Value Free:
0.26
R-Value Work:
0.23
R-Value Observed:
0.23
Space Group:
P 21 21 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Multidrug efflux pump subunit AcrB
Mutations:V340A
Chain IDs:A, B, C
Chain Length:1057
Number of Molecules:3
Biological Source:Escherichia coli K-12
Polymer Type:polypeptide(L)
Description:DARPin
Chain IDs:D, E
Chain Length:169
Number of Molecules:2
Biological Source:synthetic construct
Primary Citation
Binding and Transport of Carboxylated Drugs by the Multidrug Transporter AcrB.
J.Mol.Biol. 432 861 877 (2020)
PMID: 31881208 DOI: 10.1016/j.jmb.2019.12.025

Abstact

AcrAB(Z)-TolC is the main drug efflux transporter complex in Escherichia coli. The extrusion of various toxic compounds depends on several drug binding sites within the trimeric AcrB transporter. Membrane-localized carboxylated substrates, such as fusidic acid and hydrophobic β-lactams, access the pump via a groove between the transmembrane helices TM1 and TM2. In this article, the transport route from the initial TM1/TM2 groove binding site toward the deep binding pocket located in the periplasmic part has been addressed via molecular modeling studies followed by functional and structural characterization of several AcrB variants. We propose that membrane-embedded drugs bind initially to the TM1/TM2 groove, are oriented by the AcrB PN2 subdomain, and are subsequently transported via a PN2/PC1 interface pathway directly toward the deep binding pocket. Our work emphasizes the exploitation of multiple transport pathways by AcrB tuned to substrate physicochemical properties related to the polyspecificity of the pump.

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