The crystal structure of metal-free human EF-hand protein S100A3 at 1.7-A resolution.

S100A3 is a unique member of the EF-hand superfamily of Ca(2+)-binding proteins. It binds Ca(2+) with poor affinity (K(d) = 4-35 mm) but Zn(2+) with exceptionally high affinity (K(d) = 4 nm). This high affinity for Zn(2+) is attributed to the unusual high Cys content of S100A3. The protein is ...
highly expressed in fast proliferating hair root cells and astrocytoma pointing toward a function in cell cycle control. We determined the crystal structure of the protein at 1.7 A. The high resolution structure revealed a large distortion of the C-terminal canonical EF-hand, which most likely abolishes Ca(2+) binding. The crystal structure of S100A3 allows the prediction of one putative Zn(2+) binding site in the C terminus of each subunit of S100A3 involving Cys and His residues in the coordination of the metal ion. Zn(2+) binding induces a large conformational change in S100A3 perturbing the hydrophobic interface between two S100A3 subunits, as shown by size exclusion chromatography and CD spectroscopy.
Mesh Terms:
Amino Acid Sequence, Androstadienes, Binding Sites, Calcium, Calcium-Binding Proteins, Circular Dichroism, Crystallography, X-Ray, Cysteine, Dimerization, EF Hand Motifs, Escherichia coli, Histidine, Humans, Hydrogen Bonding, Kinetics, Models, Molecular, Molecular Sequence Data, Protein Binding, Protein Conformation, Protein Structure, Tertiary, S100 Proteins, Signal Transduction, Zinc
J. Biol. Chem.
Date: Sep. 06, 2002
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