7NPW

Cryo-EM structure of Human excitatory amino acid transporters-1 (EAAT1) in potassium buffer

Summary for 7NPW

• Entry DOI: 10.2210/pdb7npw/pdb
• EMDB information: 12524
• Descriptor: Excitatory amino acid transporter 1 (1 entity in total)
• Functional Keywords: human membrane protein, transporter, glutamate transporter, membrane protein
• Biological source: Homo sapiens (Human)
• Total number of polymer chains: 3
• Total formula weight: 153234.82

Authors

Kumar, A.,Reyes, N. (deposition date: 2021-02-28, release date: 2021-10-13, Last modification date: 2024-07-10)

Primary citation

Canul-Tec, J.C.,Kumar, A.,Dhenin, J.,Assal, R.,Legrand, P.,Rey, M.,Chamot-Rooke, J.,Reyes, N.
The ion-coupling mechanism of human excitatory amino acid transporters.
Embo J., 41:e108341-e108341, 2022

PubMed Abstract: Excitatory amino acid transporters (EAATs) maintain glutamate gradients in the brain essential for neurotransmission and to prevent neuronal death. They use ionic gradients as energy source and co-transport transmitter into the cytoplasm with Na and H , while counter-transporting K to re-initiate the transport cycle. However, the molecular mechanisms underlying ion-coupled transport remain incompletely understood. Here, we present 3D X-ray crystallographic and cryo-EM structures, as well as thermodynamic analysis of human EAAT1 in different ion bound conformations, including elusive counter-transport ion bound states. Binding energies of Na and H , and unexpectedly Ca , are coupled to neurotransmitter binding. Ca competes for a conserved Na site, suggesting a regulatory role for Ca in glutamate transport at the synapse, while H binds to a conserved glutamate residue stabilizing substrate occlusion. The counter-transported ion binding site overlaps with that of glutamate, revealing the K -based mechanism to exclude the transmitter during the transport cycle and to prevent its neurotoxic release on the extracellular side.

PubMed: 34747040
DOI: 10.15252/embj.2021108341

Experimental method

ELECTRON MICROSCOPY (3.99 Å)