1fx5

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CRYSTAL STRUCTURE ANALYSIS OF ULEX EUROPAEUS LECTIN I

Overview

The tertiary and quaternary structure of the lectin I from Ulex europaeus, (UE-I) has been determined to 2.2 A resolution. UE-I is a dimeric, metalloglycoprotein that binds the H-type 2 human blood group determinant, [alpha-L-Fucalpha(1-->2)-beta-D-Galbeta(1-->4)-beta-D-Glc NAcalpha-]. Nine, changes from the published amino acid sequence were necessary to account, for the electron density. The quaternary structural organization of UE-I, is that of the most commonly occurring legume lectin dimer. The tertiary, structure of the monomeric subunits is similar to that in the conventional, lectin subunit; however, some structural differences are noted. These, differences include a four-stranded anti-parallel "S" sheet in UE-I versus, the five-stranded S sheet in other lectin monomers. The Ala residue of the, Ala-Asp cis-peptide bond present in the carbohydrate-binding site of the, conventional lectin monomer is replaced with a Thr in the UE-I structure., Also, a novel disulfide bridge linking Cys115 and Cys150 is present. There, are two metallic ions, one calcium and the other manganese, per subunit., N-linked oligosaccharides are at residues 23 and 111 of each subunit. One, molecule of R-2-methyl-2, 4-pentanediol (R-MPD) is present in a shallow, depression on the surface of each subunit. In order to examine the binding, of the H-type 2 blood group determinant by UE-I, its beta-methyl glycoside, (H-type 2-OMe) was docked into the binding site of R-MPD. The epitope, previously identified for H-type 2-OMe by chemical mapping proved, with, only minor adjustment of amino acid residues, to be complementary to the, shallow cavity occupied by R-MPD in the structure. Several key, interactions have been proposed between the H-type 2-OMe and UE-I.

About this Structure

1FX5 is a Single protein structure of sequence from Ulex europaeus with MN, CA and MRD as ligands. Full crystallographic information is available from OCA.

Reference

The 2.2 A resolution structure of the O(H) blood-group-specific lectin I from Ulex europaeus., Audette GF, Vandonselaar M, Delbaere LT, J Mol Biol. 2000 Dec 1;304(3):423-33. PMID:11090284

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