2z48

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spinqualitylabelsall models 2z48, resolution 1.70Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal Structure of Hemolytic Lectin CEL-III Complexed with GalNac

Overview

CEL-III is a Ca(2+)-dependent hemolytic lectin, isolated from the marine, invertebrate C. echinata. The three- dimensional structure of, CEL-III/GalNAc and CEL-III/methyl alpha-galactoside (Me-alpha-Gal), complexes was solved by x-ray crystallographic analysis. In these, complexes, five carbohydrate molecules were found to be bound to two, carbohydrate-binding domains (domains 1 and 2) located in the N-terminal, 2/3 portion of the polypeptide and that contained beta-trefoil folds, similar to ricin B-chain. The 3-OH and 4-OH of bound carbohydrate, molecules were coordinated with Ca(2+) located at the subdomains 1alpha, 1gamma, 2alpha, 2beta, and 2gamma, simultaneously forming hydrogen bond, networks with nearby amino acid side chains, which is similar to, carbohydrate-binding in C-type lectins. The binding of carbohydrates was, further stabilized by aromatic amino acid residues, such as tyrosine and, tryptophan, through a stacking interaction with the hydrophobic face of, carbohydrates. Importance of amino acid residues in the, carbohydrate-binding sites were confirmed by the mutational analyses. The, orientation of bound GalNAc and Me-alpha-Gal was similar to galactose, moiety of lactose bound to the carbohydrate-binding site of the ricin, B-chain, although the ricin B-chain does not require a Ca(2+) ion for, carbohydrate-binding. The binding of the carbohydrates induced local, structural changes in carbohydrate-binding sites in subdomains 2alpha and, 2beta. Binding of GalNAc also induced a slight change in the main chain, structure of domain 3, which could be related to the conformational change, upon binding of specific carbohydrates to induce oligomerization of the, protein.

About this Structure

2Z48 is a Single protein structure of sequence from Cucumaria echinata with , , and as ligands. Full crystallographic information is available from OCA.

Reference

C-type lectin-like carbohydrate-recognition of the hemolytic lectin CEL-III containing ricin-type beta-trefoil folds., Hatakeyama T, Unno H, Kouzuma Y, Uchida T, Eto S, Hidemura H, Kato N, Yonekura M, Kusunoki M, J Biol Chem. 2007 Oct 31;. PMID:17977832

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