4o3a
From Proteopedia
Crystal structure of the glua2 ligand-binding domain in complex with L-aspartate at 1.80 a resolution
Structural highlights
FunctionGRIA2_RAT Receptor for glutamate that functions as ligand-gated ion channel in the central nervous system and plays an important role in excitatory synaptic transmission. L-glutamate acts as an excitatory neurotransmitter at many synapses in the central nervous system. Binding of the excitatory neurotransmitter L-glutamate induces a conformation change, leading to the opening of the cation channel, and thereby converts the chemical signal to an electrical impulse. The receptor then desensitizes rapidly and enters a transient inactive state, characterized by the presence of bound agonist. In the presence of CACNG4 or CACNG7 or CACNG8, shows resensitization which is characterized by a delayed accumulation of current flux upon continued application of glutamate.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] Publication Abstract from PubMedIn purification of the ionotropic glutamate receptor A2 (GluA2) ligand-binding domain (LBD), l-Glu-supplemented buffers have previously been used for protein stabilization during the procedure. This sometimes hampers structural studies of low-affinity ligands, because l-Glu is difficult to displace, despite extensive dialysis. Here, we show that l-Asp binds to full-length GluA2 with low affinity (Ki = 0.63 mm) and to the GluA2 LBD with even lower affinity (Ki = 2.6 mm), and we use differential scanning fluorimetry to show that l-Asp is able to stabilize the isolated GluA2 LBD. We also show that l-Asp can replace l-Glu during purification, providing both equal yields and purity of the resulting protein sample. Furthermore, we solved three structures of the GluA2 LBD in the presence of 7.5, 50 and 250 mm l-Asp. Surprisingly, with 7.5 mm l-Asp, the GluA2 LBD crystallized as a mixed dimer, with l-Glu being present in one subunit, and neither l-Asp nor l-Glu being present in the other subunit. Thus, residual l-Glu is retained from the expression medium. On the other hand, only l-Asp was found at the binding site when 50 or 250 mm l-Asp was used for crystallization. The binding mode observed for l-Asp at the GluA2 LBD is very similar to that described for l-Glu. Taking our findings together, we have shown that l-Asp can be used instead of l-Glu for ligand-dependent stabilization of the GluA2 LBD during purification. This will enable structural studies of low-affinity ligands for lead optimization in structure-based drug design. DATABASE: Structural data are available in the Protein Data Bank under accession numbers 4O3B (7.5 mm l-Asp), 4O3C (50 mm l-Asp), and 4O3A (250 mm l-Asp) STRUCTURED DIGITAL ABSTRACT: GluA2 and GluA2 bind by x-ray crystallography (View interaction). L-Asp is a useful tool in the purification of the ionotropic glutamate receptor A2 ligand-binding domain.,Krintel C, Frydenvang K, Ceravalls de Rabassa A, Kaern AM, Gajhede M, Pickering DS, Kastrup JS FEBS J. 2014 May;281(10):2422-30. doi: 10.1111/febs.12795. Epub 2014 Apr 17. PMID:24673938[15] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. Loading citation details.. Citations 0 reviews cite this structure No citations found See AlsoReferences
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