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Crystal structures of artocarpin, a Moraceae lectin with mannose specificity, and its complex with methyl-alpha-D-mannose: implications to the generation of carbohydrate specificity.

Abstract：

:The seeds of jack fruit (Artocarpus integrifolia) contain two tetrameric lectins, jacalin and artocarpin. Jacalin was the first lectin found to exhibit the beta-prism I fold, which is characteristic of the Moraceae plant lectin family. Jacalin contains two polypeptide chains produced by a post-translational proteolysis which has been shown to be crucial for generating its specificity for galactose. Artocarpin is a single chain protein with considerable sequence similarity with jacalin. It, however, exhibits many properties different from those of jacalin. In particular, it is specific to mannose. The structures of two crystal forms, form I and form II, of the native lectin have been determined at 2.4 and 2.5 A resolution, respectively. The structure of the lectin complexed with methyl-alpha-mannose, has also been determined at 2.9 A resolution. The structure is similar to jacalin, although differences exist in details. The crystal structures and detailed modelling studies indicate that the following differences between the carbohydrate binding sites of artocarpin and jacalin are responsible for the difference in the specificities of the two lectins. Firstly, artocarpin does not contain, unlike jacalin, an N terminus generated by post-translational proteolysis. Secondly, there is no aromatic residue in the binding site of artocarpin whereas there are four in that of jacalin. A comparison with similar lectins of known structures or sequences, suggests that, in general, stacking interactions with aromatic residues are important for the binding of galactose while such interactions are usually absent in the carbohydrate binding sites of mannose-specific lectins with the beta-prism I fold.

journal_name

J Mol Biol

journal_title

Journal of molecular biology

authors

Pratap JV,Jeyaprakash AA,Rani PG,Sekar K,Surolia A,Vijayan M

doi

10.1006/jmbi.2001.5432

keywords:

subject

Has Abstract

pub_date

2002-03-22 00:00:00

pages

237-47

issue

eissn

0022-2836

issn

1089-8638

pii

S0022283601954324

journal_volume

317

pub_type

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Crystal structures of artocarpin, a Moraceae lectin with mannose specificity, and its complex with methyl-alpha-D-mannose: implications to the generation of carbohydrate specificity.