1xtc

From Proteopedia

Revision as of 15:27, 5 November 2007

CHOLERA TOXIN

Overview

The clinical manifestations of cholera are largely attributable to the, actions of a secreted hexameric AB5 enterotoxin (choleragen). We have, independently solved and refined the three-dimensional structure of, choleragen at 2.5 A resolution. The structure of the crystalline toxin, closely resembles that described for the heat-labile enterotoxin from, Escherichia coli (LT) with which it shares 80% sequence homology. In both, cases, the wedge-shaped A subunit is loosely held high above the plane of, the pentameric B subunits by the tethering A2 chain. The most striking, difference between the two toxins occurs at the carboxyl terminus of the, A2 chain. Whereas the last 14 residues of the A2 chain of LT threading, through the central pore of the B5 assembly form an extended chain with a, terminal loop, the A2 chain of choleragen remains a nearly continuous, alpha-helix throughout its length. The four carboxyl-terminal residues of, the A2 chain (KDEL sequence), disordered in the crystal structure of LT, are clearly visible in choleragen's electron-density map. In the, accompanying article we describe the three-dimensional structure of the, isolated B pentamer of cholera toxin (choleragenoid). Comparison of the, crystalline coordinates of choleragen, choleragenoid, and LT provides a, solid three-dimensional foundation for further experimental investigation., These structures, along with those of related toxins from Shigella, dysenteria and Bordetella pertussis, offer a first step towards the, rational design of new vaccines and anti-microbial agents.

About this Structure

1XTC is a Protein complex structure of sequences from Vibrio cholerae. The following page contains interesting information on the relation of 1XTC with [Cholera Toxin]. Structure known Active Sites: CAT, GAD, GAE, GAF, GAG and GAH. Full crystallographic information is available from OCA.

Reference

The three-dimensional crystal structure of cholera toxin., Zhang RG, Scott DL, Westbrook ML, Nance S, Spangler BD, Shipley GG, Westbrook EM, J Mol Biol. 1995 Aug 25;251(4):563-73. PMID:7658473

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