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NMR SOLUTION STRUCTURE OF A COMPLEX OF CALMODULIN WITH A BINDING PEPTIDE OF THE CA2+-PUMP

Overview

The three-dimensional structure of the complex between calmodulin (CaM), and a peptide corresponding to the N-terminal portion of the CaM-binding, domain of the plasma membrane calcium pump, the peptide C20W, has been, solved by heteronuclear three-dimensional nuclear magnetic resonance (NMR), spectroscopy. The structure calculation is based on a total of 1808, intramolecular NOEs and 49 intermolecular NOEs between the peptide C20W, and calmodulin from heteronuclear-filtered NOESY spectra and a, half-filtered experiment, respectively. Chemical shift differences between, free Ca(2+)-saturated CaM and its complex with C20W as well as the, structure calculation reveal that C20W binds solely to the C-terminal half, of CaM. In addition, comparison of the methyl resonances of the nine, assigned methionine residues of free Ca(2+)-saturated CaM with those of, the CaM/C20W complex revealed a significant difference between the, N-terminal and the C-terminal domain; i.e., resonances in the N-terminal, domain of the complex were much more similar to those reported for free, CaM in contrast to those in the C-terminal half which were significantly, different not only from the resonances of free CaM but also from those, reported for the CaM/M13 complex. As a consequence, the global structure, of the CaM/C20W complex is unusual, i.e., different from other peptide, calmodulin complexes, since we find no indication for a collapsed, structure. The fine modulation in the peptide protein interface shows a, number of differences to the CaM/M13 complex studied by Ikura et al., [Ikura, M., Clore, G. M., Gronenborn, A. M., Zhu, G., Klee, C. B., and, Bax, A. (1992) Science 256, 632-638]. The unusual binding mode to only the, C-terminal half of CaM is in agreement with the biochemical observation, that the calcium pump can be activated by the C-terminal half of CaM alone, [Guerini, D., Krebs, J., and Carafoli, E. (1984) J. Biol. Chem. 259, 15172-15177].

About this Structure

1CFF is a Protein complex structure of sequences from Homo sapiens and Xenopus laevis with CA as ligand. Active as Calcium-transporting ATPase, with EC number 3.6.3.8 Full crystallographic information is available from OCA.

Reference

NMR solution structure of a complex of calmodulin with a binding peptide of the Ca2+ pump., Elshorst B, Hennig M, Forsterling H, Diener A, Maurer M, Schulte P, Schwalbe H, Griesinger C, Krebs J, Schmid H, Vorherr T, Carafoli E, Biochemistry. 1999 Sep 21;38(38):12320-32. PMID:10493800

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