The GlcNAc-binding site of Agaricus bisporus lectin is functionally active.

ZLOCOWSKI N; CARRIZO ME; LUJAN A; SMANIA A; IRAZOQUI FJ

Rosario, Argentina

Congreso; Sociedad Argentina de Investigaciones Bioquímicas; 2006

SAIB

  Agaricus bisporus lectin (ABL), obtained from commonly known champignon, is a protein with potent antiproliferative effects without any apparent cytotoxicity. The conformation of ABL was determined by x-ray diffraction. Co-crystallization of ABL with several sugars showed two different carbohydrate-binding sites. One recognizes Core 1 (Galbeta1-3GalNAcalpha-O-) of mucin-type O-glycans and the other binds GlcNAc. At present, the last sugar recognition was only demonstrated by crystallography. Using ELISA assays, the ABL interaction with terminal GlcNAc ligands was studied, and affinity constants were measured. The ABL interaction with ovalbumin was selected to demonstrate that binding is mediated by GlcNAc. This sugar and its derivative monosacharides (such as pNPalphaGlcNAc) reveal important inhibitory capacity, showing that GlcNAc-binding site of ABL is actively involved in interaction. ABL binds glycoproteins of nucleus matrix as observed by western blot and immunofluorescence. The GlcNAc inhibition is indicator of ABL recognition to GlcNAcbeta-Ser/Thr O-glycan from nucleus. The C. elegans growth is clearly reduced by the expression of recombinant 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 functions such as gene transcription, cell cycle and proliferation.