6q4p

Publication Abstract from PubMed

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 beta-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.

Binding and Transport of Carboxylated Drugs by the Multidrug Transporter AcrB.,Tam HK, Malviya VN, Foong WE, Herrmann A, Malloci G, Ruggerone P, Vargiu AV, Pos KM J Mol Biol. 2020 Feb 14;432(4):861-877. doi: 10.1016/j.jmb.2019.12.025. Epub 2019, Dec 25. PMID:31881208^[4]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.