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Manipulating the drug/proton antiport stoichiometry of the secondary multidrug transporter MdfA
Journal article   Open access   Peer reviewed

Manipulating the drug/proton antiport stoichiometry of the secondary multidrug transporter MdfA

Osnat Tirosh, Nadejda Sigal, Amir Gelman, Nadav Sahar, Nir Fluman, Shira Siemion and Eitan Bibi
Proceedings of the National Academy of Sciences - PNAS, Vol.109(31), pp.12473-12478
07/31/2012
DOI: 10.1073/pnas.1203632109
PMCID: PMC3411955
PMID: 22802625
url
https://doi.org/10.1073/pnas.1203632109View
Published (Version of record) Open Access

Abstract

Multidrug transporters are integral membrane proteins that use cellular energy to actively extrude antibiotics and other toxic compounds from cells. The multidrug/proton antiporter MdfA from Escherichia coli exchanges monovalent cationic substrates for protons with a stoichiometry of 1, meaning that it translocates only one proton per antiport cycle. This may explain why transport of divalent cationic drugs by MdfA is energetically unfavorable. Remarkably, however, we show that MdfA can be easily converted into a divalent cationic drug/>= 2 proton-antiporter, either by random mutagenesis or by rational design. The results suggest that exchange of divalent cationic drugs with two (or more) protons requires an additional acidic residue in the multidrug recognition pocket of MdfA. This outcome further illustrates the exceptional promiscuous capabilities of multidrug transporters.
Multidisciplinary Sciences Science & Technology Science & Technology - Other Topics

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