2R0H image
Deposition Date 2007-08-20
Release Date 2008-05-20
Last Version Date 2023-10-25
Entry Detail
PDB ID:
2R0H
Title:
Fungal lectin CGL3 in complex with chitotriose (chitotetraose)
Biological Source:
Source Organism:
Coprinus cinereus (Taxon ID: )
Host Organism:
Method Details:
Experimental Method:
Resolution:
1.90 Å
R-Value Free:
0.25
R-Value Work:
0.19
R-Value Observed:
0.19
Space Group:
P 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Molecule:CGL3 lectin
Gene (Uniprot):Cgl3
Chain IDs:A, B, C, D
Chain Length:164
Number of Molecules:4
Biological Source:Coprinus cinereus
Peptide-like Molecules
PRD_900017
Primary Citation
Structural Basis for Chitotetraose Coordination by CGL3, a Novel Galectin-Related Protein from Coprinopsis cinerea
J.Mol.Biol. 379 146 159 (2008)
PMID: 18440554 DOI: 10.1016/j.jmb.2008.03.062

Abstact

Recent advances in genome sequencing efforts have revealed an abundance of novel putative lectins. Among these, many galectin-related proteins, characterized by many conserved residues but intriguingly lacking critical amino acids, have been found in all corners of the eukaryotic superkingdom. Here we present a structural and biochemical analysis of one representative, the galectin-related lectin CGL3 found in the inky cap mushroom Coprinopsis cinerea. This protein contains all but one conserved residues known to be involved in beta-galactoside binding in galectins. A Trp residue strictly conserved among galectins is changed to an Arg in CGL3 (R81). Accordingly, the galectin-related protein is not able to bind lactose. Screening of a glycan array revealed that CGL3 displays preference for oligomers of beta1-4-linked N-acetyl-glucosamines (chitooligosaccharides) and GalNAc beta 1-4GlcNAc (LacdiNAc). Carbohydrate-binding affinity of this novel lectin was quantified using isothermal titration calorimetry, and its mode of chitooligosaccharide coordination not involving any aromatic amino acid residues was studied by X-ray crystallography. Structural information was used to alter the carbohydrate-binding specificity and substrate affinity of CGL3. The importance of residue R81 in determining the carbohydrate-binding specificity was demonstrated by replacing this Arg with a Trp residue (R81W). This single-amino-acid change led to a lectin that failed to bind chitooligosaccharides but gained lactose binding. Our results demonstrate that, similar to the legume lectin fold, the galectin fold represents a conserved structural framework upon which dramatically altered specificities can be grafted by few alterations in the binding site and that, in consequence, many metazoan galectin-related proteins may represent lectins with novel carbohydrate-binding specificities.

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