1C7V: NMR SOLUTION STRUCTURE OF THE CALCIUM-BOUND C-TERMINAL DOMAIN (W81-S161) OF CALCIUM VECTOR PROTEIN FROM AMPHIOXUS

Citation:
Abstract
Calcium vector protein (CaVP) from amphioxus is a two-domain, calcium-binding protein (18.3 kDa) of the calmodulin superfamily. Only two of the four EF-hand motifs (sites III and IV) have a significant binding affinity for calcium ions. We determined the solution structure of the domain containing these active sites (C-CaVP: W81-S161), in the Ca(2+)-saturated state, using NMR spectroscopy and restrained molecular dynamics. The tertiary structure is similar to other Ca(2+)-binding domains containing a pair of EF-hand motifs. The apo state has spectroscopic and thermodynamic characteristics of a molten globule, with conserved secondary structure but highly fluctuating tertiary organization. Titration of C-CaVP with Ca(2+) revealed a stepwise ion binding, with a stable equilibrium intermediate in which only site III binds a calcium ion. Despite a highly fluctuating structure of the free site IV, the calcium-bound site III has a persistent structure, with similar secondary elements but different interhelix angle and hydrophobic packing relative to the fully calcium-saturated state.
PDB ID: 1C7VDownload
MMDB ID: 13243
PDB Deposition Date: 2000/3/27
Updated in MMDB: 2007/10
Experimental Method:
solution nmr
Source Organism:
Similar Structures:
Molecular Components in 1C7V
Label Count Molecule
Protein (1 molecule)
1
Calcium Vector Protein
Molecule annotation
* Click molecule labels to explore molecular sequence information.

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