2dpq

From Proteopedia

Revision as of 14:29, 20 March 2008

The crystal structures of the calcium-bound con-G and con-T(K7gamma) dimeric peptides demonstrate a novel metal-dependent helix-forming motif

Overview

Short peptides that have the ability to form stable alpha-helices in solution are rare, and a number of strategies have been used to produce them, including the use of metal chelation to stabilize folding of the backbone. However, no example exists of a structurally well-defined helix stabilized exclusively through metal ion chelation. Conantokins (con)-G and -T are short peptides that are potent antagonists of N-methyl-D-aspartate receptor channels. While con-G exhibits no helicity alone, it undergoes a structural transition to a helical conformation in the presence of a variety of multivalent cations, especially Mg2+ and Ca2+. This complexation also results in antiparallel dimerization of two peptide helices in the presence of Ca2+, but not Mg2+. A con-T variant, con-T[K7gamma], displays very similar behavior. We have solved the crystal structures of both Ca2+/con-G and Ca2+/con-T [K7gamma] at atomic resolution. These structures clearly show the nature of the metal-dependent dimerization and helix formation and surprisingly also show that the con-G dimer interface is completely different from the con-T[K7gamma] interface, even though the metal chelation is similar in the two peptides. This represents a new paradigm in helix stabilization completely independent of the hydrophobic effect, which we define as the "metallo-zipper."

About this Structure

2DPQ is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.

Reference

The crystal structures of the calcium-bound con-G and con-T[K7gamma] dimeric peptides demonstrate a metal-dependent helix-forming motif., Cnudde SE, Prorok M, Dai Q, Castellino FJ, Geiger JH, J Am Chem Soc. 2007 Feb 14;129(6):1586-93. Epub 2007 Jan 23. PMID:17243678

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