One high-order ion-coupling mechanism generates multiple SLC1A stoichiometries

dEAAT2 in Drosophila melanogaster is an ion-independent electroneutral exchanger, but two point mutations restore Na+, H+, and K+ dependence and complex ion coupling.

• Why it matters: EAAT transport depends on coupled Na+/H+ uptake and K+ counter-transport, while a substrate-activated Cl− conductance’s role is unclear. Clarifying how ion coupling evolved is key to understanding glutamate clearance and excitotoxicity.
• What they did: The authors functionally characterized dEAAT2, then used cryo-EM and computational simulations to test ion transport capability. They introduced two point mutations to confer Na+, H+, and K+ dependence and assessed taurine transport with Cl−.
• The result: dEAAT2’s taurine transport forms a complex with Cl−, creating a unique Cl− dependence independent of uncoupled Cl− flux. The results suggest ancestral EAAT exchangers retain machinery for high-order ion coupling seen in human transporters.

AI summary of the abstract · may contain errors · not medical advice · read the paper.