1b8l
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Calcium-bound D51A/E101D/F102W Triple Mutant of Beta Carp Parvalbumin
OverviewOverview
BACKGROUND: The EF-hand family is a large set of Ca(2+)-binding proteins, that contain characteristic helix-loop-helix binding motifs that are, highly conserved in sequence. Members of this family include parvalbumin, and many prominent regulatory proteins such as calmodulin and troponin C., EF-hand proteins are involved in a variety of physiological processes, including cell-cycle regulation, second messenger production, muscle, contraction, microtubule organization and vision. RESULTS: We have, determined the structures of parvalbumin mutants designed to explore the, role of the last coordinating residue of the Ca(2+)-binding loop. An E101D, substitution has been made in the parvalbumin EF site. The substitution, decreases the Ca(2+)-binding affinity 100-fold and increases the, Mg(2+)-binding affinity 10-fold. Both the Ca(2+)- and Mg(2+)-bound, structures have been determined, and a structural basis has been proposed, for the metal-ion-binding properties. CONCLUSIONS: The E101D mutation does, not affect the Mg(2+) coordination geometry of the binding loop, but it, does pull the F helix 1.1 A towards the loop. The E101D-Ca(2+) structure, reveals that this mutant cannot obtain the sevenfold coordination, preferred by Ca(2+), presumably because of strain limits imposed by, tertiary structure. Analysis of these results relative to previously, reported structural information supports a model wherein the, characteristics of the last coordinating residue and the plasticity of the, Ca(2+)-binding loop delimit the allowable geometries for the coordinating, sphere.
About this StructureAbout this Structure
1B8L is a Single protein structure of sequence from Cyprinus carpio with CO3 and CA as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Metal-ion affinity and specificity in EF-hand proteins: coordination geometry and domain plasticity in parvalbumin., Cates MS, Berry MB, Ho EL, Li Q, Potter JD, Phillips GN Jr, Structure. 1999 Oct 15;7(10):1269-78. PMID:10545326
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