Full domain closure of the ligand-binding core of the ionotropic glutamate receptor iGluR5 induced by the high affinity agonist dysiherbaine and the functional antagonist 8,9-dideoxyneodysiherbaine
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Full domain closure of the ligand-binding core of the ionotropic glutamate receptor iGluR5 induced by the high affinity agonist dysiherbaine and the functional antagonist 8,9-dideoxyneodysiherbaine. / Frydenvang, Karla Andrea; Lash, L Leanne; Naur, Peter; Postila, Pekka A; Pickering, Darryl S; Smith, Caleb M; Gajhede, Michael; Sasaki, Makoto; Sakai, Ryuichi; Pentikäinen, Olli T; Swanson, Geoffrey T; Kastrup, Jette Sandholm.
In: Journal of Biological Chemistry, Vol. 284, No. 21, 2009, p. 14219-14229.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Full domain closure of the ligand-binding core of the ionotropic glutamate receptor iGluR5 induced by the high affinity agonist dysiherbaine and the functional antagonist 8,9-dideoxyneodysiherbaine
AU - Frydenvang, Karla Andrea
AU - Lash, L Leanne
AU - Naur, Peter
AU - Postila, Pekka A
AU - Pickering, Darryl S
AU - Smith, Caleb M
AU - Gajhede, Michael
AU - Sasaki, Makoto
AU - Sakai, Ryuichi
AU - Pentikäinen, Olli T
AU - Swanson, Geoffrey T
AU - Kastrup, Jette Sandholm
PY - 2009
Y1 - 2009
N2 - The prevailing structural model for ligand activation of ionotropic glutamate receptors posits that agonist efficacy arises from the stability and magnitude of induced domain closure in the ligand-binding core structure. Here we describe an exception to the correlation between ligand efficacy and domain closure. A weakly efficacious partial agonist of very low potency for homomeric iGluR5 kainate receptors, 8,9-dideoxy-neodysiherbaine (MSVIII-19), induced a fully closed iGluR5 ligand-binding core. The degree of relative domain closure, ~30 degrees , was similar to that we resolved with the structurally related high-affinity agonist dysiherbaine (DH), and to that of L-glutamate. The pharmacological activity of MSVIII-19 was confirmed in patch-clamp recordings from transfected HEK293 cells, where MSVIII-19 predominantly inhibits iGluR5-2a, with little activation apparent at a high concentration (1 mM) of MSVIII-19 (<1% of mean glutamate-evoked currents). To determine the efficacy of the ligand quantitatively, we constructed concentration-response relationships for MSVIII-19 following potentiation of steady-state currents with concanavalin A (EC50 3.6 muM) and on the non-desensitizing receptor mutant iGluR5-2b(Y506C/L768C) (EC50 8.1 muM). MSVIII-19 exhibited a maximum of 16% of full agonist efficacy as measured in parallel recordings with glutamate. Molecular dynamics simulations and electrophysiological recordings confirm that the specificity of MSVIII-19 for iGluR5 is partly attributable to inter-domain hydrogen bonds residues Glu441 and Ser721 in the iGluR5-S1S2 structure. The weaker interactions of MSVIII-19 with iGluR5 compared to DH, together with altered stability of the inter-domain interaction, may be responsible for the apparent uncoupling of domain closure and channel opening in this kainate receptor subunit.
AB - The prevailing structural model for ligand activation of ionotropic glutamate receptors posits that agonist efficacy arises from the stability and magnitude of induced domain closure in the ligand-binding core structure. Here we describe an exception to the correlation between ligand efficacy and domain closure. A weakly efficacious partial agonist of very low potency for homomeric iGluR5 kainate receptors, 8,9-dideoxy-neodysiherbaine (MSVIII-19), induced a fully closed iGluR5 ligand-binding core. The degree of relative domain closure, ~30 degrees , was similar to that we resolved with the structurally related high-affinity agonist dysiherbaine (DH), and to that of L-glutamate. The pharmacological activity of MSVIII-19 was confirmed in patch-clamp recordings from transfected HEK293 cells, where MSVIII-19 predominantly inhibits iGluR5-2a, with little activation apparent at a high concentration (1 mM) of MSVIII-19 (<1% of mean glutamate-evoked currents). To determine the efficacy of the ligand quantitatively, we constructed concentration-response relationships for MSVIII-19 following potentiation of steady-state currents with concanavalin A (EC50 3.6 muM) and on the non-desensitizing receptor mutant iGluR5-2b(Y506C/L768C) (EC50 8.1 muM). MSVIII-19 exhibited a maximum of 16% of full agonist efficacy as measured in parallel recordings with glutamate. Molecular dynamics simulations and electrophysiological recordings confirm that the specificity of MSVIII-19 for iGluR5 is partly attributable to inter-domain hydrogen bonds residues Glu441 and Ser721 in the iGluR5-S1S2 structure. The weaker interactions of MSVIII-19 with iGluR5 compared to DH, together with altered stability of the inter-domain interaction, may be responsible for the apparent uncoupling of domain closure and channel opening in this kainate receptor subunit.
KW - Former Faculty of Pharmaceutical Sciences
U2 - 10.1074/jbc.M808547200
DO - 10.1074/jbc.M808547200
M3 - Journal article
C2 - 19297335
VL - 284
SP - 14219
EP - 14229
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 21
ER -
ID: 11859094