TY - JOUR TI - Substrate transport and anion permeation proceed through distinct pathways in glutamate transporters AU - Cheng, Mary Hongying AU - Torres-Salazar, Delany AU - Gonzalez-Suarez, Aneysis D AU - Amara, Susan G AU - Bahar, Ivet A2 - Shan, Yibing VL - 6 PY - 2017 DA - 2017/06/01 SP - e25850 C1 - eLife 2017;6:e25850 DO - 10.7554/eLife.25850 UR - https://doi.org/10.7554/eLife.25850 AB - Advances in structure-function analyses and computational biology have enabled a deeper understanding of how excitatory amino acid transporters (EAATs) mediate chloride permeation and substrate transport. However, the mechanism of structural coupling between these functions remains to be established. Using a combination of molecular modeling, substituted cysteine accessibility, electrophysiology and glutamate uptake assays, we identified a chloride-channeling conformer, iChS, transiently accessible as EAAT1 reconfigures from substrate/ion-loaded into a substrate-releasing conformer. Opening of the anion permeation path in this iChS is controlled by the elevator-like movement of the substrate-binding core, along with its wall that simultaneously lines the anion permeation path (global); and repacking of a cluster of hydrophobic residues near the extracellular vestibule (local). Moreover, our results demonstrate that stabilization of iChS by chemical modifications favors anion channeling at the expense of substrate transport, suggesting a mutually exclusive regulation mediated by the movement of the flexible wall lining the two regions. KW - human excitatory amino acid transporter 1 KW - anion channeling KW - Aspartate transporter from Pyrococcus horikoshii JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -