scholarly journals Stargazin promotes closure of the AMPA receptor ligand-binding domain

2014 ◽  
Vol 144 (6) ◽  
pp. 503-512 ◽  
Author(s):  
David M. MacLean ◽  
Swarna S. Ramaswamy ◽  
Mei Du ◽  
James R. Howe ◽  
Vasanthi Jayaraman
Keyword(s):  
Ligand Binding ◽  
Ampa Receptor ◽  
Bound States ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Binding Domain ◽  
Ligand Binding Domain ◽  
Structural Mechanism ◽  
Functional Studies ◽  
Cleft Closure

Transmembrane AMPA receptor (AMPAR) regulatory proteins (TARPs) markedly enhance AMPAR function, altering ligand efficacy and receptor gating kinetics and thereby shaping the postsynaptic response. The structural mechanism underlying TARP effects on gating, however, is unknown. Here we find that the prototypical member of the TARP family, stargazin or γ-2, rescues gating deficits in AMPARs carrying mutations that destabilize the closed-cleft states of the ligand-binding domain (LBD), suggesting that stargazin reverses the effects of these mutations and likely stabilizes closed LBD states. Furthermore, stargazin promotes a more closed conformation of the LBD, as indicated by reduced accessibility to the large antagonist NBQX. Consistent with the functional studies, luminescence resonance energy transfer experiments directly demonstrate that the AMPAR LBD is on average more closed in the presence of stargazin, in both the apo and agonist-bound states. The additional cleft closure and/or stabilization of the more closed-cleft states of the LBD is expected to translate to higher agonist efficacy and could contribute to the structural mechanism for stargazin modulation of AMPAR function.

scholarly journals Effects of T686A Mutation on the Structural Stability of the AMPA Receptor Ligand-Binding Domain

2018 ◽  
Vol 114 (3) ◽  
pp. 125a
Author(s):  
Hiraku Oshima ◽  
Suyong Re ◽  
Masayoshi Sakakura ◽  
Hideo Takahashi ◽  
Yuji Sugita
Keyword(s):  
Ligand Binding ◽  
Structural Stability ◽  
Ampa Receptor ◽  
Binding Domain ◽  
Ligand Binding Domain ◽  
Receptor Ligand

scholarly journals LRET Investigations of Conformational Changes in the Ligand Binding Domain of a Functional AMPA Receptor†

Biochemistry ◽  
2008 ◽  
Vol 47 (38) ◽  
pp. 10027-10032 ◽  
Author(s):  
Jennifer Gonzalez ◽  
Anu Rambhadran ◽  
Mei Du ◽  
Vasanthi Jayaraman
Keyword(s):  
Ligand Binding ◽  
Ampa Receptor ◽  
Conformational Changes ◽  
Binding Domain ◽  
Ligand Binding Domain

scholarly journals Correlating efficacy and desensitization with GluK2 ligand-binding domain movements

Open Biology ◽  
2013 ◽  
Vol 3 (5) ◽  
pp. 130051 ◽  
Author(s):  
Naushaba Nayeem ◽  
Olga Mayans ◽  
Tim Green
Keyword(s):  
Ligand Binding ◽  
Conformational Changes ◽  
Binding Domain ◽  
Ligand Binding Domain ◽  
Anion Binding ◽  
Charge Balance ◽  
Dimer Interface ◽  
Ligand Affinity ◽  
Cleft Closure ◽  
Binding Cleft

Gating of AMPA- and kainate-selective ionotropic glutamate receptors can be defined in terms of ligand affinity, efficacy and the rate and extent of desensitization. Crucial insights into all three elements have come from structural studies of the ligand-binding domain (LBD). In particular, binding-cleft closure is associated with efficacy, whereas dissociation of the dimer formed by neighbouring LBDs is linked with desensitization. We have explored these relationships in the kainate-selective subunit GluK2 by studying the effects of mutating two residues (K531 and R775) that form key contacts within the LBD dimer interface, but whose truncation unexpectedly attenuates desensitization. One mutation (K531A) also switches the relative efficacies of glutamate and kainate. LBD crystal structures incorporating these mutations revealed several conformational changes that together explain their phenotypes. K531 truncation results in new dimer contacts, consistent with slower desensitization and sideways movement in the ligand-binding cleft correlating with efficacy. The tested mutants also disrupted anion binding; no chloride was detected in the dimer-interface site, including in R775A where absence of chloride was the only structural change evident. From this, we propose that the charge balance in the GluK2 LBD dimer interface maintains a degree of instability, necessary for rapid and complete desensitization.

Structural analysis of the positive AMPA receptor modulators CX516 and Me-CX516 in complex with the GluA2 ligand-binding domain

2013 ◽  
Vol 69 (9) ◽  
pp. 1645-1652 ◽  
Author(s):  
Christian Krintel ◽  
Kasper Harpsøe ◽  
Linda G. Zachariassen ◽  
Dan Peters ◽  
Karla Frydenvang ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Ligand Binding ◽  
Ampa Receptor ◽  
Binding Domain ◽  
Ligand Binding Domain ◽  
Receptor Modulators

scholarly journals Characterization of the functional role of the N-glycans in the AMPA receptor ligand-binding domain

2003 ◽  
Vol 84 (5) ◽  
pp. 1184-1192 ◽  
Author(s):  
Arja Pasternack ◽  
Sarah K. Coleman ◽  
James Féthière ◽  
Dean R. Madden ◽  
Jean-Pierre LeCaer ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Ampa Receptor ◽  
Functional Role ◽  
Binding Domain ◽  
Ligand Binding Domain ◽  
Receptor Ligand

scholarly journals Dynamics of Cleft Closure of the GluA2 Ligand-binding Domain in the Presence of Full and Partial Agonists Revealed by Hydrogen-Deuterium Exchange

2013 ◽  
Vol 288 (38) ◽  
pp. 27658-27666 ◽  
Author(s):  
Ahmed H. Ahmed ◽  
Christopher P. Ptak ◽  
Michael K. Fenwick ◽  
Ching-Lin Hsieh ◽  
Gregory A. Weiland ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Ligand Binding ◽  
Binding Domain ◽  
Deuterium Exchange ◽  
Ligand Binding Domain ◽  
Hydrogen Deuterium Exchange ◽  
Channel Activation ◽  
Hydrogen Deuterium ◽  
Cleft Closure ◽  
The Stability

The majority of excitatory neurotransmission in the CNS is mediated by tetrameric AMPA receptors. Channel activation begins with a series of interactions with an agonist that binds to the cleft between the two lobes of the ligand-binding domain of each subunit. Binding leads to a series of conformational transitions, including the closure of the two lobes of the binding domain around the ligand, culminating in ion channel opening. Although a great deal has been learned from crystal structures, determining the molecular details of channel activation, deactivation, and desensitization requires measures of dynamics and stabilities of hydrogen bonds that stabilize cleft closure. The use of hydrogen-deuterium exchange at low pH provides a measure of the variation of stability of specific hydrogen bonds among agonists of different efficacy. Here, we used NMR measurements of hydrogen-deuterium exchange to determine the stability of hydrogen bonds in the GluA2 (AMPA receptor) ligand-binding domain in the presence of several full and partial agonists. The results suggest that the stabilization of hydrogen bonds between the two lobes of the binding domain is weaker for partial than for full agonists, and efficacy is correlated with the stability of these hydrogen bonds. The closure of the lobes around the agonists leads to a destabilization of the hydrogen bonding in another portion of the lobe interface, and removing an electrostatic interaction in Lobe 2 can relieve the strain. These results provide new details of transitions in the binding domain that are associated with channel activation and desensitization.

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