A novel mode of carbohydrate recognition in jacalin, a Moraceae plant lectin with a beta-prism fold.
Jacalin, a tetrameric two-chain lectin (66,000 Mr) from jackfruit seeds, is highly specific for the tumour associated T-antigenic disaccharide. The crystal structure of jacalin with methyl-alpha-D-galactose reveals that each subunit has a three-fold symmetric beta-prism fold made up of three four-stranded beta-sheets. The lectin exhibits a novel carbohydrate-binding site involving the N terminus of the alpha-chain which is generated through a post-translational modification involving proteolysis, the first known instance where such a modification has been used to confer carbohydrate specificity. This new lectin fold may be characteristic of the Moraceae plant family. The structure provides an explanation for the relative affinities of the lectin for galactose derivatives and provides insights into the structural basis of its T-antigen specificity.
Sankaranarayanan
R
R
Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India.
Sekar
K
K
Banerjee
R
R
Sharma
V
V
Surolia
A
A
Vijayan
M
M
D000595:Amino Acid Sequence; D001665:Binding Sites; D002241:Carbohydrates / Q000737:chemistry*; D018360:Crystallography, X-Ray / Q000379:methods; D005690:Galactose / Q000737:chemistry; D007369:Interferon Inducers / Q000737:chemistry*; D037102:Lectins / Q000737:chemistry*; D008969:Molecular Sequence Data; D010936:Plant Extracts; D037121:Plant Lectins; D011487:Protein Conformation; D017510:Protein Folding
D002241:Carbohydrates; D007369:Interferon Inducers; D037102:Lectins; D010936:Plant Extracts; D037121:Plant Lectins; C043696:jacalin; D005690:Galactose