Ion coupling, permeation, and regulation in glutamate transporters

Glutamate is the primary excitatory neurotransmitter in the human brain, responsible for cognition, memory
formation, learning, and pain signaling, among other functions. Two families of integral membrane glutamate
transporters are essential players in glutamatergic neurotransmission. The VGLUT family loads glutamate into
the synaptic vesicles, and the EAAT family removes the neurotransmitter from the synaptic cleft following
neurotransmission. The dysregulation of these transporters under pathologic conditions and neurologic disorders
disrupts glutamate homeostasis leading to aberrant neurotransmission, glutamate excitotoxicity, and neuronal
death. Ions play crucial roles in the function of these transporters. Electrochemical gradients of ions power the
concentrative glutamate uptake and regulate transporters. In addition, transporters can conduct ions in a manner
uncoupled from the neurotransmitter uptake, modulating electrochemical trans-membrane gradients. This grant
proposal aims to understand the mechanism and evolution of ion-coupling mechanisms, mechanisms of the
uncoupled ion permeation in health and disease, and ion-mediated regulation. We will combine bioinformatics,
single-particle cryo-electron microscopy, single-molecule fluorescence microscopy, and other biophysical and
biochemical approaches to pinpoint the residues, the conformational states, and the dynamic properties of
transporters underlying their interactions with ions.

Grant Number: 5R37NS134865-02
NIH Institute/Center: NIH
Principal Investigator: Olga Boudker