Transport dynamics in a glutamate transporter homologue. Academic Article uri icon

Overview

MeSH

  • Aspartic Acid
  • Biological Transport
  • Fluorescence Resonance Energy Transfer
  • Mutation
  • Protein Binding
  • Protein Structure, Tertiary
  • Sodium

MeSH Major

  • Amino Acid Transport System X-AG
  • Models, Molecular
  • Pyrococcus horikoshii

abstract

  • Glutamate transporters are integral membrane proteins that catalyse neurotransmitter uptake from the synaptic cleft into the cytoplasm of glial cells and neurons. Their mechanism of action involves transitions between extracellular (outward)-facing and intracellular (inward)-facing conformations, whereby substrate binding sites become accessible to either side of the membrane. This process has been proposed to entail transmembrane movements of three discrete transport domains within a trimeric scaffold. Using single-molecule fluorescence resonance energy transfer (smFRET) imaging, we have directly observed large-scale transport domain movements in a bacterial homologue of glutamate transporters. We find that individual transport domains alternate between periods of quiescence and periods of rapid transitions, reminiscent of bursting patterns first recorded in single ion channels using patch-clamp methods. We propose that the switch to the dynamic mode in glutamate transporters is due to separation of the transport domain from the trimeric scaffold, which precedes domain movements across the bilayer. This spontaneous dislodging of the substrate-loaded transport domain is approximately 100-fold slower than subsequent transmembrane movements and may be rate determining in the transport cycle.

publication date

  • October 3, 2013

has subject area

  • Amino Acid Transport System X-AG
  • Aspartic Acid
  • Biological Transport
  • Fluorescence Resonance Energy Transfer
  • Models, Molecular
  • Mutation
  • Protein Binding
  • Protein Structure, Tertiary
  • Pyrococcus horikoshii
  • Sodium

Research

keywords

  • Journal Article

Identity

Language

  • eng

PubMed Central ID

  • PMC3829612

Digital Object Identifier (DOI)

  • 10.1038/nature12265

PubMed ID

  • 23792560

Additional Document Info

start page

  • 114

end page

  • 118

volume

  • 502

number

  • 7469