Glutamate transporters are essential players in glutamatergic neurotransmission in the brain, where they maintain extracellular glutamate below cytotoxic levels and allow for rounds of transmission. The structural bases of their function are well established, particularly within a model archaeal homologue, sodium and aspartate symporter GltPh. However, the mechanism of gating on the cytoplasmic side of the membrane remains ambiguous. We report Cryo-EM structures of GltPh reconstituted into nanodiscs, including those structurally constrained in the cytoplasm-facing state and either apo, bound to sodium ions only, substrate, or blockers. The structures show that both substrate translocation and release involve movements of the bulky transport domain through the lipid bilayer. They further reveal a novel mode of inhibitor binding and show how solutes release is coupled to protein conformational changes. Finally, we describe how domain movements are associated with the displacement of bound lipids and significant membrane deformations, highlighting the potential regulatory role of the bilayer.
- Olga Boudker
- Olga Boudker
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Lucy R Forrest, National Institute of Neurological Disorders and Stroke, National Institutes of Health, United States
- Received: April 30, 2020
- Accepted: November 5, 2020
- Accepted Manuscript published: November 6, 2020 (version 1)
? 2020, Wang & Boudker
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