1RRO

REFINEMENT OF RECOMBINANT ONCOMODULIN AT 1.30 ANGSTROMS RESOLUTION

Summary for 1RRO

• Entry DOI: 10.2210/pdb1rro/pdb
• Descriptor: RAT ONCOMODULIN, CALCIUM ION (3 entities in total)
• Functional Keywords: calcium-binding protein
• Biological source: Rattus rattus (black rat)
• Total number of polymer chains: 1
• Total formula weight: 12227.38

Authors

Ahmed, F.R.,Rose, D.R.,Evans, S.V.,Pippy, M.E.,To, R. (deposition date: 1992-08-27, release date: 1993-10-31, Last modification date: 2024-02-14)

Primary citation

Ahmed, F.R.,Rose, D.R.,Evans, S.V.,Pippy, M.E.,To, R.
Refinement of recombinant oncomodulin at 1.30 A resolution.
J.Mol.Biol., 230:1216-1224, 1993

PubMed Abstract: A refinement of the oncomodulin crystal structure at 1.30 A resolution has been carried out with X-ray data from the recombinant protein. The crystallographic R-factor values are 0.169 for 19,995 reflections in the range 6.0 to 1.30 A, which were used for the restrained least-squares refinement, and 0.176 for 20,186 observed reflections in the range 10.0 to 1.30 A. This high resolution refinement has enabled us to make more definitive statements about the molecular structure than was possible heretofore. The present model includes residues 1 to 108, the two Ca2+ of the CD and EF loops, two intermolecular Ca2+, and 103 water molecules per oncomodulin molecule. The electron density maps indicate disordered orientations for ten residues on the hydrophilic surface of the molecule. The pattern of molecular aggregation via intermolecular Ca2+, which occurs in the native rat oncomodulin structure, is also present in the recombinant oncomodulin structure. The Cys18 side-chain is not in a position that would be easily accessible for molecular dimerization via a disulphide bond. The substitution of Glu59, which is preserved in all the determined species of parvalbumin, by Asp59 in oncomodulin seems to break a stabilizing hydrogen bond in the CD loop and render the main-chain in positions 59 to 60 somewhat unstable. This instability in the CD loop, and the strong tendency of oncomodulin for molecular aggregation via intermolecular Ca2+, appear to be the two outstanding features that may account for oncomodulin's biological peculiarities.

PubMed: 8487302
DOI: 10.1006/jmbi.1993.1237

Experimental method

X-RAY DIFFRACTION (1.3 Å)