1awy
From Proteopedia
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NMR STRUCTURE OF CALCIUM BOUND CONFORMER OF CONANTOKIN G, MINIMIZED AVERAGE STRUCTURE
Overview
Conantokin G is a gamma-carboxyglutamic acid- (Gla-) containing conotoxin, isolated from the venom of the marine cone snail Conus geographus. This, 17-residue polypeptide, which contains five gamma-carboxyglutamic acid, residues, is a N-methyl-d-aspartate- (NMDA-) type glutamate receptor, antagonist. To investigate the role of gamma-carboxyglutamic acid in the, calcium-induced structural transition of conantokin G, we determined the, three-dimensional structure of the conantokin G/Ca2+ complex by, two-dimensional 1H NMR spectroscopy and compared it to the high-resolution, structure of conantokin G in the absence of metal ions [Rigby et al., (1997) Biochemistry 36, 6906]. Complete resonance assignments were made by, two dimensional 1H NMR spectroscopy at pH 5.6 in the presence of, saturating amounts of Ca2+. Distance geometry and simulated annealing, methods were used to derive 23 convergent structures from a set of 302, interproton distance restraints and two torsion angle measurements. A, high-resolution structure, with the backbone root mean square deviation to, the geometric average of the 23 structures of 0.6 +/- 0.1 A, contains a, linear alpha-helix from Gla 3 to Lys 15. Gla residues 3, 7, 10, and 14 are, aligned in a linear array on one face of the helix. A genetic algorithm, was applied to determine the calcium positions in conantokin G, and the, conantokin G/Ca2+ complex refined by molecular simulation. Upon binding of, Ca2+ to gamma-carboxyglutamic acid, conantokin G undergoes a, conformational transition from a distorted curvilinear 310 helix to a, linear alpha-helix. Occupancy of the metal binding sites, defined by, gamma-carboxyglutamic acids, results in formation of a calcium-carboxylate, network that linearizes the helix and exposes the hydrophobic amino acids, on the opposite face of the helix.
About this Structure
1AWY is a Single protein structure of sequence from Conus geographus with as ligand. Known structural/functional Site: . Full crystallographic information is available from OCA.
Reference
Role of gamma-carboxyglutamic acid in the calcium-induced structural transition of conantokin G, a conotoxin from the marine snail Conus geographus., Rigby AC, Baleja JD, Li L, Pedersen LG, Furie BC, Furie B, Biochemistry. 1997 Dec 16;36(50):15677-84. PMID:9398296
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