Target enzyme recognition by calmodulin : 2.4 Å structure of a calmodulin-peptide complex

• Published in: Science (American Association for the Advancement of Science) 1992-08, Vol.257 (5074), p.1251-1255
• Main Authors: MEADOR, W. E, MEANS, A. R, QUIOCHO, F. A
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Analytical, structural and metabolic biochemistry; Biological and medical sciences; Calmodulin - chemistry; Crystallography; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Models, Molecular; Molecular Sequence Data; Myosin-Light-Chain Kinase - metabolism; Protein Conformation; Transferases
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1519061

The crystal structure of calcium-bound calmodulin (Ca(2+)-CaM) bound to a peptide analog of the CaM-binding region of chicken smooth muscle myosin light chain kinase has been determined and refined to a resolution of 2.4 angstroms (A). The structure is compact and has the shape of an ellipsoid (axial ratio approximately 2:1). The bound CaM forms a tunnel diagonal to its long axis that engulfs the helical peptide, with the hydrophobic regions of CaM melded into a single area that closely covers the hydrophobic side of the peptide. There is a remarkably high pseudo-twofold symmetry between the closely associated domains. The central helix of the native CaM is unwound and expanded into a bend between residues 73 and 77. About 185 contacts (less than 4 A) are formed between CaM and the peptide, with van der Waals contacts comprising approximately 80% of this total.