TY  - JOUR
AU  - Fahlke, Christoph
AU  - Balandin, Taras
AU  - Astashkin, Roman
AU  - Alleva, Claudia
AU  - Machtens, Jan-Philipp
AU  - Gordeliy, Valentin
AU  - Baeken, Christian
AU  - Kovalev, Kirill
AU  - Berndt, Meike
TI  - Na + -dependent gate dynamics and electrostatic attraction ensure substrate coupling in glutamate transporters
JO  - Science advances
VL  - 6
IS  - 47
SN  - 2375-2548
CY  - Washington, DC [u.a.]
PB  - Assoc.
M1  - FZJ-2020-03832
SP  - eaba9854 -
PY  - 2020
AB  - Excitatory amino acid transporters (EAATs) harness [Na+], [K+], and [H+] gradients for fast and efficient glutamate removal from the synaptic cleft. Since each glutamate is cotransported with three Na+ ions, [Na+] gradients are the predominant driving force for glutamate uptake. We combined all-atom molecular dynamics simulations, fluorescence spectroscopy, and x-ray crystallography to study Na+:substrate coupling in the EAAT homolog GltPh. A lipidic cubic phase x-ray crystal structure of wild-type, Na+-only bound GltPh at 2.5-Å resolution revealed the fully open, outward-facing state primed for subsequent substrate binding. Simulations and kinetic experiments established that only the binding of two Na+ ions to the Na1 and Na3 sites ensures complete HP2 gate opening via a conformational selection-like mechanism and enables high-affinity substrate binding via electrostatic attraction. The combination of Na+-stabilized gate opening and electrostatic coupling of aspartate to Na+ binding provides a constant Na+:substrate transport stoichiometry over a broad range of neurotransmitter concentrations.
LB  - PUB:(DE-HGF)16
C6  - pmid:33208356
UR  - <Go to ISI:>//WOS:000592173500003
DO  - DOI:10.1126/sciadv.aba9854
UR  - https://juser.fz-juelich.de/record/885449
ER  -