Sequence and structural determinants of ligand-dependent alternating access of a MATE transporter
Year: 2020
Type: article
Abstract: MATE transporters are ubiquitous ion-coupled antiporters that extrude structurally- and chemically-dissimilar molecules and have been implicated in conferring multidrug resistance. Here, we integrate Double Electron Electron Resonance (DEER) in conjunction with functional assays and site-directed mutagenesis of conserved residues to illuminate principles of ligand-dependent alternating access of PfMATE, a proton-coupled MATE from the hyperthermophilic archaeon Pyrococcus furiosus . Pairs of spin labels monitoring the two sides of the transporter reconstituted into nanodiscs reveal large amplitude movement of helices that alter the orientation of a putative substrate binding cavity. We found that acidic pH favors formation of an inward-facing (IF) conformation, whereas elevated pH (>7) and the substrate rhodamine 6G stabilizes an outward-facing (OF) conformation. PfMATE isomerization between outward-facing and inward-facing conformations is driven by protonation of a previously unidentified intracellular glutamate residue that is critical for drug resistance. Our results can be framed in a mechanistic model of transport that addresses central aspects of ligand coupling and alternating access.
Institution: Vanderbilt University
Language: English
Subfield: Oncology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W3007428911