Conformational Selection and Functional Dynamics of Calmodulin: A 19F NMR Study.
 

Conformational Selection and Functional Dynamics of Calmodulin: A 19F NMR Study.

Related Articles Conformational Selection and Functional Dynamics of Calmodulin: A 19F NMR Study.

Biochemistry. 2014 Aug 22;

Authors: Hoang J, Prosser RS

Abstract
Calcium-bound calmodulin (CaM-4Ca2+) is innately promiscuous with regard to its protein interaction network within the cell. A key facet to the interaction process involves conformational selection. In the absence of a binding peptide, CaM-4Ca2+ adopts an equilibrium between a native state (N) and a weakly populated near-native peptide-bound like state (I), whose lifetime is on the order of 1.5 ms at 37ºC, based on 19F NMR CPMG relaxation dispersion measurements. This peptide-bound like state of CaM-4Ca2+ is entropically stabilized (?S = 280 ± 35 J/mol K) relative to the native state, water-depleted, and likely parental to specific bound states. Solvent depletion, conformational selection, and flexibility of the peptide-bound like state may be important in priming the protein for binding. At higher temperatures, the exchange rate, k¬ex, appears to markedly slow, suggesting the onset of misfolded or off-pathway states, which retards interconversion between N and I. 19F NMR CPMG relaxation dispersion experiments on both CaM and the separate N-terminal and C-terminal domains reveal the cooperative role of the two domains in the binding process and the flexibility of the N-terminal domain in facilitating binding. Thus, upon binding of calcium, calmodulin establishes its interaction with a multitude of protein binding partners, through a combination of conformational selection to a state which is parental to the peptide-bound state, and finally, induced fit.


PMID: 25148136 [PubMed - as supplied by publisher]



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