Charge neutralization of the active site glutamates does not limit substrate binding and transport by small multidrug resistance transporter EmrE.

ABSTRACT: EmrE, a small multidrug resistance transporter from Escherichia coli, confers broad-spectrum resistance to polyaromatic cations and quaternary ammonium compounds. Previous transport assays demonstrate that EmrE transports a +1 and a +2 substrate with the same stoichiometry of two protons:one cationic substrate. This suggests that EmrE substrate binding capacity is limited to neutralization of the two essential glutamates, E14_A and E14_B (one from each subunit in the antiparallel homodimer), in the primary binding site. Here, we explicitly test this hypothesis, since EmrE has repeatedly broken expectations for membrane protein structure and transport mechanism. We previously showed that EmrE can bind a +1 cationic substrate and proton simultaneously, with cationic subst

SUBMITTER: Spreacker PJ 

PROVIDER: S-EPMC9860125 | biostudies-literature | 2023 Feb

REPOSITORIES: biostudies-literature