1c7v

From Proteopedia

Revision as of 10:07, 20 November 2007

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

Overview

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.

About this Structure

1C7V is a Single protein structure of sequence from Branchiostoma lanceolatum. Full crystallographic information is available from OCA.

Reference

Sequential calcium binding to the regulatory domain of calcium vector protein reveals functional asymmetry and a novel mode of structural rearrangement., Theret I, Baladi S, Cox JA, Sakamoto H, Craescu CT, Biochemistry. 2000 Jul 11;39(27):7920-6. PMID:10891072

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