Purification and characterization of a new lectin from the edible mushroom Boletus edulis with antiproliferative effect on tumor cell lines

A new lectin was isolated from the fruiting bodies of the ediblemushroom Boletus edulis by affinity chromatography on a chitincolumn. Boletus edulis lectin (BEL) exhibited a molecular mass ofapproximately 15 kDa in SDS-PAGE under reducing conditions.BEL cDNA was cloned and the deduced primary sequence,corresponding to 142 amino acids and a calculated molecular massof 15597 Da, showed a high similarity with the members of thefungal saline-soluble lectin family. The binding properties of thelectin were studied by competitive enzyme-lectin assays (CELA).The results show, as it was previously described for the Agaricusbisporus lectin (ABL), that BEL would have two sugar bindingsites with different specificity, one for Thomsen Friedenreich antigen(TF antigen, Galβ1-3GalNAcα-O-Ser/Thr) related residues and theother for N-acetyl glucosamine. The lectin also exhibited a potentdose-dependent antiproliferative activity toward some human tumorcell lines with no apparent cytotoxicity