1BU3 image
Entry Detail
PDB ID:
1BU3
Keywords:
Title:
REFINED CRYSTAL STRUCTURE OF CALCIUM-BOUND SILVER HAKE (PI 4.2) PARVALBUMIN AT 1.65 A.
Biological Source:
Source Organism:
PDB Version:
Deposition Date:
1998-08-30
Release Date:
1999-08-10
Method Details:
Experimental Method:
Resolution:
1.65 Å
R-Value Free:
0.25
R-Value Work:
0.21
R-Value Observed:
0.21
Space Group:
C 2 2 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:CALCIUM-BINDING PROTEIN
Chain IDs:A
Chain Length:109
Number of Molecules:1
Biological Source:Merluccius bilinearis
Ligand Molecules
Primary Citation
X-Ray crystal structure and molecular dynamics simulations of silver hake parvalbumin (Isoform B).
Protein Sci. 9 73 82 (2000)
PMID: 10739249

Abstact

Parvalbumins constitute a class of calcium-binding proteins characterized by the presence of several helix-loop-helix (EF-hand) motifs. In a previous study (Revett SP, King G, Shabanowitz J, Hunt DF, Hartman KL, Laue TM, Nelson DJ, 1997, Protein Sci 7:2397-2408), we presented the sequence of the major parvalbumin isoform from the silver hake (Merluccius bilinearis) and presented spectroscopic and structural information on the excised "EF-hand" portion of the protein. In this study, the X-ray crystal structure of the silver hake major parvalbumin has been determined to high resolution, in the frozen state, using the molecular replacement method with the carp parvalbumin structure as a starting model. The crystals are orthorhombic, space group C2221, with a = 75.7 A, b = 80.7 A, and c = 42.1 A. Data were collected from a single crystal grown in 15% glycerol, which served as a cryoprotectant for flash freezing at -188 degrees C. The structure refined to a conventional R-value of 21% (free R 25%) for observed reflections in the range 8 to 1.65 A [1 > 2sigma(I)]. The refined model includes an acetylated amino terminus, 108 residues (characteristic of a beta parvalbumin lineage), 2 calcium ions, and 114 water molecules per protein molecule. The resulting structure was used in molecular dynamics (MD) simulations focused primarily on the dynamics of the ligands coordinating the Ca2+ ions in the CD and EF sites. MD simulations were performed on both the fully Ca2+ loaded protein and on a Ca2+ deficient variant, with Ca2+ only in the CD site. There was substantial agreement between the MD and X-ray results in addressing the issue of mobility of key residues in the calcium-binding sites, especially with regard to the side chain of Ser55 in the CD site and Asp92 in the EF site.

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