Binding of a negative allosteric modulator and competitive antagonist can occur simultaneously at the ionotropic glutamate receptor GluA2

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DOI

  • Christian Krintel, Københavns Universitet, Lund University
  • ,
  • Jerzy Dorosz, Københavns Universitet
  • ,
  • Andreas Haahr Larsen, Københavns Universitet
  • ,
  • Thor Seneca Thorsen, Københavns Universitet
  • ,
  • Raminta Venskutonytė, Københavns Universitet, Sect. of Neurosci. at Lund Univ.
  • ,
  • Osman Mirza, Københavns Universitet
  • ,
  • Michael Gajhede, Københavns Universitet
  • ,
  • Thomas Boesen
  • Jette Sandholm Kastrup, Københavns Universitet

Ionotropic glutamate receptors are ligand-gated ion channels governing neurotransmission in the central nervous system. Three major types of antagonists are known for the AMPA-type receptor GluA2: competitive, noncompetitive (i.e., negative allosteric modulators; NAMs) used for treatment of epilepsy, and uncompetitive antagonists. We here report a 4.65 Å resolution X-ray structure of GluA2, revealing that four molecules of the competitive antagonist ZK200775 and four molecules of the NAM GYKI53655 are capable of binding at the same time. Using negative stain electron microscopy, we show that GYKI53655 alone or ZK200775/GYKI53655 in combination predominantly results in compact receptor forms. The agonist AMPA provides a mixed population of compact and bulgy shapes of GluA2 not impacted by addition of GYKI53655. Taken together, this suggests that the two different mechanisms of antagonism that lead to channel closure are independent and that the distribution between bulgy and compact receptors primarily depends on the ligand bound in the glutamate binding site. Database: The atomic coordinates and structure factors from the crystal structure determination have been deposited in the Protein Data Bank under accession code https://doi.org/10.2210/pdb6RUQ/pdb. The electron microscopy 3D reconstruction volumes have been deposited in EMDB (EMD-4875: Apo; EMD-4920: ZK200775/GYKI53655; EMD-4921: AMPA compact; EMD-4922: AMPA/GYKI53655 bulgy; EMD-4923: GYKI53655; EMD-4924: AMPA bulgy; EMD-4925: AMPA/GYKI53655 compact).

OriginalsprogEngelsk
TidsskriftFEBS Journal
Vol/bind288
Nummer3
Sider (fra-til)995-1007
Antal sider13
ISSN1742-464X
DOI
StatusUdgivet - feb. 2021

Bibliografisk note

Funding Information:
We would like to thank Eric Gouaux for kindly providing the GluA2cryst construct, Heidi Peterson for help with GluA2cryst purification, Ole Kristensen for help using XIA2 and beamline scientists at ESRF, Grenoble, France; MAX‐lab, Lund, Sweden; BESSY, Berlin, Germany; SLS, Villigen, Switzerland; and Diamond, Oxford, UK, for their help during data collections. Funding is acknowledged from GluTarget, Danish Council for Independent Research—Medical Sciences, Lundbeck Foundation, Danscatt, and BioStructX.

Publisher Copyright:
© 2020 Federation of European Biochemical Societies

Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.

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