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Structural basis for the specificity of basic winged bean lectin for the Tn-antigen: A crystallographic, thermodynamic and modelling study

Kulkarni, Kiran A and Sinha, Sharmistha and Katiyar, Samiksha and Surolia, Avadhesha and Vijayan, Mamannamana and Suguna, Kaza (2005) Structural basis for the specificity of basic winged bean lectin for the Tn-antigen: A crystallographic, thermodynamic and modelling study. In: Febs Letters, 579 (30). pp. 6775-6780.

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Abstract

The crystal structure of winged bean basic agglutinin in complex with GalNAc-\alpha-O-Ser (Tn-antigen) has been elucidated at 2.35 A resolution in order to characterize the mode of binding of Tn-antigen with the lectin. The Gal moiety occupies the primary binding site and makes interactions similar to those found in other Gal/GalNAc specific legume lectins. The nitrogen and oxygen atoms of the acetamido group of the sugar make two hydrogen bonds with the protein atoms whereas its methyl group is stabilized by hydrophobic interactions. A water bridge formed between the terminal oxygen atoms of the serine residue of the Tn-antigen and the side chain oxygen atom of Asn128 of the lectin increase the affinity of the lectin for Tn-antigen compared to that for GalNAc. A comparison with the available structures reveals that while the interactions of the glyconic part of the antigen are conserved, the mode of stabilization of the serine residue differs and depends on the nature of the protein residues in its vicinity. The structure provides a qualitative explanation for the thermodynamic parameters of the complexation of the lectin with Tn-antigen. Modeling studies indicate the possibility of an additional hydrogen bond with the lectin when the antigen is part of a glycoprotein.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to Elsevier.
Keywords: Legume lectin; Crystal structure; Winged bean lectin; Tn-antigen; Carbohydrate specificity
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited: 02 Feb 2006
Last Modified: 19 Sep 2010 04:23
URI: http://eprints.iisc.ernet.in/id/eprint/5279

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