The EF‐hand domain: A globally cooperative structural unit

• Published in: Protein science Vol. 11; no. 2; pp. 198 - 205
• Main Authors: Nelson, Melanie R., Thulin, Eva, Fagan, Patricia A., Forsén, Sture, Chazin, Walter J.
• Format: Journal Article
• Language: English
• Published: Bristol Cold Spring Harbor Laboratory Press 01.02.2002
• Subjects: Binding Sites; CaBP, Ca2+‐binding protein; calbindin, calbindin D9k; Calbindins; Calcium - metabolism; Calcium‐binding protein; CaM, calmodulin; Chemical Sciences; conformational change; Crystallography, X-Ray; CSI, chemical shift index; EF Hand Motifs - genetics; EF-hand; Fysikalisk kemi; Kemi; Magnetic Resonance Spectroscopy; Models, Molecular; mutagenesis; Mutation - genetics; Natural Sciences; Naturvetenskap; NMR spectroscopy; NMR, nuclear magnetic resonance; NOE, nuclear Overhauser effect; Physical Chemistry; Protein Conformation; protein engineering; S100 Calcium Binding Protein G - chemistry; Structure-Activity Relationship
• ISSN: 0961-8368; 1469-896X; 1469-896X
• DOI: 10.1110/ps.33302

EF‐hand Ca2+‐binding proteins participate in both modulation of Ca2+ signals and direct transduction of the ionic signal into downstream biochemical events. The range of biochemical functions of these proteins is correlated with differences in the way in which they respond to the binding of Ca2+. The EF‐hand domains of calbindin D9k and calmodulin are homologous, yet they respond to the binding of calcium ions in a drastically different manner. A series of comparative analyses of their structures enabled the development of hypotheses about which residues in these proteins control the calcium‐induced changes in conformation. To test our understanding of the relationship between protein sequence and structure, we specifically designed the F36G mutation of the EF‐hand protein calbindin D9k to alter the packing of helices I and II in the apoprotein. The three‐dimensional structure of apo F36G was determined in solution by nuclear magnetic resonance spectroscopy and showed that the design was successful. Surprisingly, significant structural perturbations also were found to extend far from the site of mutation. The observation of such long‐range effects provides clear evidence that four‐helix EF‐hand domains should be treated as a single globally cooperative unit. A hypothetical mechanism for how the long‐range effects are transmitted is described. Our results support the concept of energetic and structural coupling of the key residues that are crucial for a protein's fold and function.