Membrane Topology of the Multidrug Transporter MdfA: Complementary Gene Fusion Studies Reveal a Nonessential C-terminal Domain

Overview

Journal J Bacteriol

Publisher American Society for Microbiology

Specialty Microbiology

Date 2002 May 25

PMID 12029048

Citations 12

Authors

Julia Adler

Eitan Bibi

Affiliations

Soon will be listed here.

Abstract

The hydrophobicity profile and sequence alignment of the Escherichia coli multidrug transporter MdfA indicate that it belongs to the 12-transmembrane-domain family of transporters. According to this prediction, MdfA contains a single membrane-embedded charged residue (Glu26), which was shown to play an important role in substrate recognition. To test the predicted secondary structure of MdfA, we analyzed complementary pairs of hybrids of MdfA-PhoA (alkaline phosphatase, functional in the periplasm) and MdfA-Cat (chloramphenicol acetyltransferase, functional in the cytoplasm), generated in all the putative cytoplasmic and periplasmic loops of MdfA. Our results support the 12-transmembrane topology model and the suggestion that except for Glu26, no other charged residues are present in the membrane domain of MdfA. Surprisingly, by testing the ability of the truncated MdfA-Cat and MdfA-PhoA hybrids to confer multidrug resistance, we demonstrate that the entire C-terminal transmembrane domain and the cytoplasmic C terminus are not essential for MdfA-mediated drug resistance and transport.

Citing Articles

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The Multidrug Transporter MdfA Deviates from the Canonical Model of Alternating Access of MFS Transporters.

Yardeni E, Mishra S, Stein R, Bibi E, Mchaourab H J Mol Biol. 2020; 432(20):5665-5680.

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Probing the solution structure of the E. coli multidrug transporter MdfA using DEER distance measurements with nitroxide and Gd(III) spin labels.

Yardeni E, Bahrenberg T, Stein R, Mishra S, Zomot E, Graham B Sci Rep. 2019; 9(1):12528.

PMID: 31467343 PMC: 6715713. DOI: 10.1038/s41598-019-48694-0.

Biochemistry of bacterial multidrug efflux pumps.

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Escherichia coli SRP, its protein subunit Ffh, and the Ffh M domain are able to selectively limit membrane protein expression when overexpressed.

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