1CLL

CALMODULIN STRUCTURE REFINED AT 1.7 ANGSTROMS RESOLUTION

Summary for 1CLL

• Entry DOI: 10.2210/pdb1cll/pdb
• Descriptor: CALMODULIN, CALCIUM ION, ETHANOL, ... (4 entities in total)
• Functional Keywords: calcium-binding protein
• Biological source: Homo sapiens (human)
• Cellular location: Cytoplasm, cytoskeleton, spindle: P62158
• Total number of polymer chains: 1
• Total formula weight: 16927.73

Authors

Chattopadhyaya, R.,Quiocho, F.A. (deposition date: 1992-09-29, release date: 1993-10-31, Last modification date: 2024-02-07)

Primary citation

Chattopadhyaya, R.,Meador, W.E.,Means, A.R.,Quiocho, F.A.
Calmodulin structure refined at 1.7 A resolution.
J.Mol.Biol., 228:1177-1192, 1992

PubMed Abstract: We have determined and refined the crystal structure of a recombinant calmodulin at 1.7 A resolution. The structure was determined by molecular replacement, using the 2.2 A published native bovine brain structure as the starting model. The final crystallographic R-factor, using 14,469 reflections in the 10.0 to 1.7 A range with structure factors exceeding 0.5 sigma, is 0.216. Bond lengths and bond angle distances have root-mean-square deviations from ideal values of 0.009 A and 0.032 A, respectively. The final model consists of 1279 non-hydrogen atoms, including four calcium ions, 1130 protein atoms, including three Asp118 side-chain atoms in double conformation, 139 water molecules and one ethanol molecule. The electron densities for residues 1 to 4 and 148 of calmodulin are poorly defined, and not included in our model, except for main-chain atoms of residue 4. The calmodulin structure from our crystals is very similar to the earlier 2.2 A structure described by Babu and coworkers with a root-mean-square deviation of 0.36 A. Calmodulin remains a dumb-bell-shaped molecule, with similar lobes and connected by a central alpha-helix. Each lobe contains three alpha-helices and two Ca2+ binding EF hand loops, with a short antiparallel beta-sheet between adjacent EF hand loops and one non-EF hand loop. There are some differences in the structure of the central helix. The crystal packing is extensively studied, and facile crystal growth along the z-axis of the triclinic crystals is explained. Herein, we describe hydrogen bonding in the various secondary structure elements and hydration of calmodulin.

PubMed: 1474585
DOI: 10.1016/0022-2836(92)90324-D

Experimental method

X-RAY DIFFRACTION (1.7 Å)