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| {{STRUCTURE_2r0f| PDB=2r0f | SCENE= }} | | {{STRUCTURE_2r0f| PDB=2r0f | SCENE= }} |
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| '''Ligand free structure of fungal lectin CGL3'''
| | ===Ligand free structure of fungal lectin CGL3=== |
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| ==Overview==
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| 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.
| | The line below this paragraph, {{ABSTRACT_PUBMED_18440554}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 18440554 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_18440554}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Lectin]] | | [[Category: Lectin]] |
| [[Category: Sugar binding protein]] | | [[Category: Sugar binding protein]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu May 22 21:36:49 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 05:58:48 2008'' |
