1bod
THE SOLUTION STRUCTURES OF MUTANT CALBINDIN D9K'S, AS DETERMINED BY NMR, SHOW THAT THE CALCIUM BINDING SITE CAN ADOPT DIFFERENT FOLDS
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OverviewOverview
The complete 1H NMR assignments have been obtained for five mutant, proteins of calbindin D9k and the three-dimensional solution structures, determined for two of the mutants. The structures have been determined, using distance geometry and simulated annealing, with distance constraints, from NMR. All mutants have modifications in the first calcium-binding site, of calbindin (the N-terminal site designated the pseudo-EF-hand). The 3D, structure of the mutant with the most extensive modifications in the, pseudo-EF-hand shows that the site has turned inside-out and coordinates, calcium as in the normal EF-hand (the C-terminal site). In a, pseudo-EF-hand loop the calcium is coordinated by main-chain carbonyls, whereas calcium in the normal EF-hand is coordinated by side-chain, carboxylates. The 3D structures and 1H NMR assignments show that in order, to accomplish a change in the coordinating ligands of the pseudo-EF-hand, the loop must be 12 residues long and have glycine in the sixth position., It does, however, seem possible to have alanine instead of aspartic acid, in the first calcium coordinating position. The overall global fold of the, proteins has not been affected by the mutations in the calcium-binding, site, as compared to the wild-type calbindin D9k [Kordel, J., Skelton, N., J., Akke, M., & Chazin, W. J. (1993) J. Mol. Biol. (in press)]. The, structures consist of two helix-calcium-binding loop-helix motifs, the so, called EF-hands, and the loops are connected by a short antiparallel, beta-sheet. All helices are pairwise in an antiparallel orientation.
About this StructureAbout this Structure
1BOD is a Single protein structure of sequence from Bos taurus. Full crystallographic information is available from OCA.
ReferenceReference
The solution structures of mutant calbindin D9k's, as determined by NMR, show that the calcium-binding site can adopt different folds., Johansson C, Ullner M, Drakenberg T, Biochemistry. 1993 Aug 24;32(33):8429-38. PMID:8357794
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