Carbohydrate specificity and quaternary association in basic winged bean lectin: X-ray analysis of the lectin at 2.5 angstrom resolution

Prabu, Moses M and Sankaranarayanan, R and Puri, KD and Sharma, V and Surolia, A and Vijayan, M and Suguna, K (1998) Carbohydrate specificity and quaternary association in basic winged bean lectin: X-ray analysis of the lectin at 2.5 angstrom resolution. In: Journal of Molecular Biology, 276 (4). pp. 787-796.

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Abstract

The structure of basic Winged Bean Agglutinin (WBAI) with two dimeric molecules complexed with methyl-alpha-D-galactopyranoside in the asymmetric unit, has been determined by the molecular replacement method and refined with 2.5 Angstrom X-ray intensity data. The polypeptide chain of each monomer has the characteristic legume lectin tertiary fold. The structure clearly defines the lectin-carbohydrate interactions. It reveals how the unusually long variable loop in the binding region endows the lectin with its characteristic sugar specificity. The lectin forms non-canonical dimers of the type found in Erythrina corallodendron lectin (EcorL) even though glycosylation, unlike in EcorL, does not prevent the formation of canonical dimers. The structure thus further demonstrates that the mode of dimerisation of legume lectins is not necessarily determined by the covalently bound carbohydrate but is governed by features intrinsic to the protein. The present analysis and our earlier work on peanut lectin (PNA), show that legume lectins are a family of proteins in which small alterations in essentially the same tertiary structure lead to wide variations in quaternary association. A relationship among the non-canonical modes of dimeric association in legume lectins is presented

Item Type:	Journal Article
Publication:	Journal of Molecular Biology
Publisher:	Academic Press
Additional Information:	Copyright of this article belongs to Academic Press.
Keywords:	legume lectin;protein crystallography;blood group specificity;quaternary association;carbohydrate binding.
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	13 Mar 2009 05:22
Last Modified:	19 Sep 2010 05:00
URI:	http://eprints.iisc.ac.in/id/eprint/18199

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