BEL beta-Trefoil. A novel lectin with antitumoral properties in king bolete (Boletus edulis) mushrooms

BOVI, MICHELE; CENCI, LUCIA; PERDUCA, MASSIMILIANO; CAPALDI, STEFANO; CARRIZO, MARÍA E.; CIVIERO, LAURA; CHIARELLI, LAURENT; GALLIANO, MONICA; MONACO, HUGO L.

GLYCOBIOLOGY

OXFORD UNIV PRESS INC

Lugar: Oxford; Año: 2013 vol. 23 p. 578 - 592

0959-6658

A novel lectin was purified from the fruiting bodies of king bolete mushrooms Boletus edulis, also called porcino, cep or penny bun). The lectin was structurally characterized: its amino acid sequence and three dimensional structure were determined. The new protein is a homodimer and each protomer folds as beta-trefoil domain and therefore we propose the name BEL beta-trefoil to distinguish it from the other lectin that has been described in these mushrooms: BEL. The lectin has potent anti-proliferative effects on human cancer cells which confers to it an interesting therapeutic potential as an antineoplastic agent. Several crystal forms of the apoprotein and of complexes with different carbohydrates were studied by X-ray diffraction. The structure of the apoprotein was solved at 1.12 Å resolution. The interaction of the lectin with lactose, galactose, N-acetylgalactosamine and the T-antigen disaccharide, Galbeta1-3GalNAc, was examined in detail. All the three potential binding sites present in the beta-trefoil fold are occupied in at least one crystal form and are described in detail in this paper. No important conformational changes are observed in the lectin when comparing its co-crystals with carbohydrates with those of the ligand free protein.