Peptide binding by a fragment of calmodulin composed of EF-hands 2 and 3.
Biochemistry
; 46(29): 8525-36, 2007 Jul 24.
Article
en En
| MEDLINE
| ID: mdl-17595060
Calmodulin (CaM) is composed of two EF-hand domains tethered by a flexible linker. Upon Ca2+-binding, a fragment of CaM encompassing EF-hands 2 and 3 (CaM2/3; residues 46-113) folds into a structure remarkably similar to the N- and C-domains of CaM. In this study, we demonstrate that Ca2+-ligated CaM2/3 can also bind to a peptide representing the CaM-recognition sequence of skeletal muscle myosin light chain kinase (M13) with an equimolar stoichiometry and a dissociation constant of 0.40 +/- 0.05 microM. On the basis of an analytical ultracentrifugation measurement, the resulting complex exists as an equilibrium mixture of 2:2 heterotetrameric and 1:1 heterodimeric species. Chemical shift perturbation mapping indicates that, similar to CaM, the peptide associates with a hydrophobic groove crossing both EF-hands in CaM2/3. However, upon binding the M13 peptide, many residues in CaM2/3 yielded two equal intensity NMR signals with the same 15N relaxation properties. Thus, the 2:2 CaM2/3-M13 tetramer, which predominates under the conditions used for these studies, is asymmetric with each component adopting spectroscopically distinguishable conformations within the complex. CaM2/3 also weakly stimulates the phosphatase activity of calcineurin and inhibits stimulation by native CaM. These studies highlight the remarkable plasticity of EF-hand association and expand the diverse repertoire of mechanisms possible for CaM-target protein interactions.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Fragmentos de Péptidos
/
Quinasa de Cadena Ligera de Miosina
/
Calmodulina
/
Motivos EF Hand
Tipo de estudio:
Prognostic_studies
Límite:
Humans
Idioma:
En
Revista:
Biochemistry
Año:
2007
Tipo del documento:
Article
Pais de publicación:
Estados Unidos