7SFQ

EmrE S64V Mutant Bound to tetra(4-fluorophenyl)phosphonium at pH 8.0

Summary for 7SFQ

• Entry DOI: 10.2210/pdb7sfq/pdb
• NMR Information: BMRB: 30957
• Descriptor: Multidrug transporter EmrE, tetrakis(4-fluorophenyl)phosphanium (2 entities in total)
• Functional Keywords: multidrug resistance protein, smr transporter, efflux protein, proton-coupled, membrane protein
• Biological source: Escherichia coli
• Total number of polymer chains: 2
• Total formula weight: 24362.01

Authors

Shcherbakov, A.A.,Spreacker, P.J.,Dregni, A.J.,Henzler-Wildman, K.A.,Hong, M. (deposition date: 2021-10-04, release date: 2022-03-02, Last modification date: 2024-05-15)

Primary citation

Shcherbakov, A.A.,Spreacker, P.J.,Dregni, A.J.,Henzler-Wildman, K.A.,Hong, M.
High-pH structure of EmrE reveals the mechanism of proton-coupled substrate transport.
Nat Commun, 13:991-991, 2022

PubMed Abstract: The homo-dimeric bacterial membrane protein EmrE effluxes polyaromatic cationic substrates in a proton-coupled manner to cause multidrug resistance. We recently determined the structure of substrate-bound EmrE in phospholipid bilayers by measuring hundreds of protein-ligand H-F distances for a fluorinated substrate, 4-fluoro-tetraphenylphosphonium (F-TPP), using solid-state NMR. This structure was solved at low pH where one of the two proton-binding Glu14 residues is protonated. Here, to understand how substrate transport depends on pH, we determine the structure of the EmrE-TPP complex at high pH, where both Glu14 residues are deprotonated. The high-pH complex exhibits an elongated and hydrated binding pocket in which the substrate is similarly exposed to the two sides of the membrane. In contrast, the low-pH complex asymmetrically exposes the substrate to one side of the membrane. These pH-dependent EmrE conformations provide detailed insights into the alternating-access model, and suggest that the high-pH conformation may facilitate proton binding in the presence of the substrate, thus accelerating the conformational change of EmrE to export the substrate.

PubMed: 35181664
DOI: 10.1038/s41467-022-28556-6

Experimental method

SOLID-STATE NMR