Transport rate of EAAT2 is regulated by amino acid located at the interface between the scaffolding and substrate transport domains. (October 2020)

• Record Type: Journal Article
• Authors: Duffield, Michael; Patel, Avkash; Mortensen, Ole V.; Schnur, Dora; Gonzalez-Suarez, Aneysis D.; Torres-Salazar, Delany; Fontana, Andréia C.K.
• Is Part Of: Neurochemistry international. Volume 139(2020)
• Publication Date: 2020-10
• Subjects: EAAT2 -- Glutamate transporter -- Glutamate uptake -- G298A -- Transport enhancement; Neurochemistry -- Periodicals; Neurochemistry -- Periodicals; Neurochimie -- Périodiques; Neurochemistry; Periodicals; 612.804205
• DOI: 10.1016/j.neuint.2020.104792
• Languages: English
• ISSNs: 0197-0186

Abstract

Abstract: Excitatory Amino Acid Transporters (EAATs) are plasma membrane proteins responsible for maintenance of low extracellular concentrations of glutamate in the CNS. Dysfunction in their activity is implicated in various neurological disorders. Glutamate transport by EAATs occurs through the movement of the central transport domain relative to the scaffold domain in the EAAT membrane protein. Previous studies suggested that residues located within the interface of these two domains in EAAT2, the main subtype of glutamate transporter in the brain, are involved in regulating transport rates. We used mutagenesis, structure-function relationship, surface protein expression and electrophysiology studies, in transfected COS-7 cells and oocytes, to examine residue glycine at position 298, which is located within this interface. Mutation G298A results in increased transport rate without changes in surface expression, suggesting a more hydrophobic and larger alanine results in facilitated transport movement. The increased transport rate does not involve changes in sodium affinity. Electrophysiological currents show that G298A increase both transport and anion currents, suggesting faster transitions through the transport cycle. This work identifies a region critically involved in setting the glutamate transport rate. Highlights: Dysregulation of glutamate transport is involved in many CNS disorders. The interface between transport and scaffold domains is involved in transport rate regulation. Mutation G298A in glutamate transporter EAAT2 increases transport rate. Increased transport does not involve changes in surface expression or sodium affinity. Increased transport rate and anion currents suggest faster transport cycle transitions.