Structural studies of antineoplastic lectins in edible mushrooms

BOVI, MICHELE; CARRIZO, MARÍA E.; CAPALDI, STEFANO; PERDUCA, MASSIMILIANO; MONACO, HUGO L.

Villaggio Guglielmo, Copanello di Stalettì, Italia

Congreso; 1st Meeting of the Italian and Spanish Crystallographic Associations (MISCA); 2007

Italian and Spanish Crystallographic Associations (MISCA)

A new lectin was isolated from the fruiting bodies of the edible mushroom Boletus edulis (king bolete mushrooms) by affinity chromatography on a chitin column. Boletus edulis lectin (BEL) has a mass of approximately 15 kDa in SDS-PAGE under reducing conditions and shows several basic isoforms in an isoelectric focusing gel. Its sequence, obtained by cloning its cDNA, is 142 amino acid long and shows a high similarity with the members of the fungal saline-soluble lectin family. Studies on the binding properties of the lectin show that, like Agaricus bisporus lectin (ABL), BEL has two different binding sites: one with specificity for the Thomsen Friedenreich antigen (TF antigen, Galβ1-3GalNAcα-O-Ser/Thr), the other with specificity for N-Acetyl-Glucosamine. The crystals belong to space group P6122 (n°178), with unit-cell parameters a = b = 122.93, c = 103.15 Å. The apo form diffracts to 1.82 Å (Rsym of 5.61%), the co-crystals with the two different ligands diffract to 2.30 Å (Rsym of 11.32%). Interaction studies between the lectin and human tumor cells showed that BEL exhibits a potent dose-dependent antiproliferative activity.