Computationally Discovered Potentiating Role of Glycans on NMDA Receptors

Sci Rep. 2017 Apr 5;7:44578. doi: 10.1038/srep44578.

Abstract

N-methyl-D-aspartate receptors (NMDARs) are glycoproteins in the brain central to learning and memory. The effects of glycosylation on the structure and dynamics of NMDARs are largely unknown. In this work, we use extensive molecular dynamics simulations of GluN1 and GluN2B ligand binding domains (LBDs) of NMDARs to investigate these effects. Our simulations predict that intra-domain interactions involving the glycan attached to residue GluN1-N440 stabilize closed-clamshell conformations of the GluN1 LBD. The glycan on GluN2B-N688 shows a similar, though weaker, effect. Based on these results, and assuming the transferability of the results of LBD simulations to the full receptor, we predict that glycans at GluN1-N440 might play a potentiator role in NMDARs. To validate this prediction, we perform electrophysiological analysis of full-length NMDARs with a glycosylation-preventing GluN1-N440Q mutation, and demonstrate an increase in the glycine EC50 value. Overall, our results suggest an intramolecular potentiating role of glycans on NMDA receptors.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Binding Sites
  • Gene Expression
  • Glycine / pharmacology
  • Glycosylation
  • Humans
  • Kinetics
  • Molecular Dynamics Simulation
  • Mutation
  • Nerve Tissue Proteins / chemistry*
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism
  • Oocytes / cytology
  • Oocytes / drug effects
  • Oocytes / metabolism*
  • Patch-Clamp Techniques
  • Polysaccharides / chemistry*
  • Polysaccharides / metabolism
  • Protein Binding
  • Protein Conformation, alpha-Helical
  • Protein Conformation, beta-Strand
  • Protein Interaction Domains and Motifs
  • Receptors, N-Methyl-D-Aspartate / chemistry*
  • Receptors, N-Methyl-D-Aspartate / genetics
  • Receptors, N-Methyl-D-Aspartate / metabolism
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Thermodynamics
  • Xenopus laevis

Substances

  • GRIN1 protein, human
  • NR2B NMDA receptor
  • Nerve Tissue Proteins
  • Polysaccharides
  • Receptors, N-Methyl-D-Aspartate
  • Recombinant Proteins
  • Glycine