The GlcNAc-binding site of Agaricus bisporus lectin is functionality active

ZLOCOWSKI, NATACHA; CARRIZO, MARIA E; LUJAN, ADELA; NORES, GUSTAVO A; SMANIA, ANDREA; IRAZOQUI, FERNANDO J

Rosario, Santa Fe, Argentina

Congreso; XLII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2006

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Agaricus bisporus lectin (ABL), obtained from commonly knownchampignon, is a protein with potent antiproliferative effectswithout any apparent cytotoxicity. The conformation of ABL wasdetermined by x-ray diffraction. Co-crystallization of ABL withseveral sugars showed two different carbohydrate-binding sites.One recognizes Core 1 (Galbeta1-3GalNAcalpha-O-) of mucintypeO-glycans and the other binds GlcNAc. At present, the lastsugar recognition was only demonstrated by crystallography.Using ELISA assays, the ABL interaction with terminal GlcNAcligands was studied, and affinity constants were measured. TheABL interaction with ovalbumin was selected to demonstrate thatbinding is mediated by GlcNAc. This sugar and its derivativemonosacharides (such as pNPalphaGlcNAc) reveal importantinhibitory capacity, showing that GlcNAc-binding site of ABL isactively involved in interaction. ABL binds glycoproteins ofnucleus matrix as observed by western blot andimmunofluorescence. The GlcNAc inhibition is indicator of ABLrecognition to GlcNAcbeta-Ser/Thr O-glycan from nucleus. TheC. elegans growth is clearly reduced by the expression ofrecombinant ABL in E. coli. Purified ABL affects the mobility of C.elegans that is recovered in the presence of glycoconjugates.Through sugar recognition, ABL could affect cellular functionssuch as gene transcription, cell cycle and proliferation.