4F2Q

Quisqualate bound to the D655A mutant of the ligand binding domain of GluA3

Summary for 4F2Q

• Entry DOI: 10.2210/pdb4f2q/pdb
• Related: 4F1Y 4F22 4F29 4F2O 4F31 4F39 4F3B 4F3G
• Descriptor: Glutamate receptor 3, (S)-2-AMINO-3-(3,5-DIOXO-[1,2,4]OXADIAZOLIDIN-2-YL)-PROPIONIC ACID, ZINC ION, ... (4 entities in total)
• Functional Keywords: glutamate receptor, glua3, glur3, ampa receptor, s1s2, lbd, neurotransmitter receptor, quisqualate, transport protein-agonist complex, transport protein/agonist
• Biological source: Rattus norvegicus (rat); More
• Cellular location: Cell membrane ; Multi-pass membrane protein : P19492
• Total number of polymer chains: 1
• Total formula weight: 29180.93

Authors

Ahmed, A.H.,Oswald, R.E. (deposition date: 2012-05-08, release date: 2012-05-30, Last modification date: 2024-11-06)

Primary citation

Holley, S.M.,Ahmed, A.H.,Srinivasan, J.,Murthy, S.E.,Weiland, G.A.,Oswald, R.E.,Nowak, L.M.
The loss of an electrostatic contact unique to AMPA receptor ligand binding domain 2 slows channel activation.
Biochemistry, 51:4015-4027, 2012

PubMed Abstract: Ligand-gated ion channels undergo conformational changes that transfer the energy of agonist binding to channel opening. Within ionotropic glutamate receptor (iGluR) subunits, this process is initiated in their bilobate ligand binding domain (LBD) where agonist binding to lobe 1 favors closure of lobe 2 around the agonist and allows formation of interlobe hydrogen bonds. AMPA receptors (GluAs) differ from other iGluRs because glutamate binding causes an aspartate-serine peptide bond in a flexible part of lobe 2 to rotate 180° (flipped conformation), allowing these residues to form cross-cleft H-bonds with tyrosine and glycine in lobe 1. This aspartate also contacts the side chain of a lysine residue in the hydrophobic core of lobe 2 by a salt bridge. We investigated how the peptide flip and electrostatic contact (D655-K660) in GluA3 contribute to receptor function by examining pharmacological and structural properties with an antagonist (CNQX), a partial agonist (kainate), and two full agonists (glutamate and quisqualate) in the wildtype and two mutant receptors. Alanine substitution decreased the agonist potency of GluA3(i)-D655A and GluA3(i)-K660A receptor channels expressed in HEK293 cells and differentially affected agonist binding affinity for isolated LBDs without changing CNQX affinity. Correlations observed in the crystal structures of the mutant LBDs included the loss of the D655-K660 electrostatic contact, agonist-dependent differences in lobe 1 and lobe 2 closure, and unflipped D(A)655-S656 bonds. Glutamate-stimulated activation was slower for both mutants, suggesting that efficient energy transfer of agonist binding within the LBD of AMPA receptors requires an intact tether between the flexible peptide flip domain and the rigid hydrophobic core of lobe 2.

PubMed: 22512472
DOI: 10.1021/bi3001837

Experimental method

X-RAY DIFFRACTION (2.202 Å)