Characterization of Cytotoxic Lactose Binding Lectin from Sulphur Polypore, Laetiporus sulphureus (Agaricomycetes), from Algeria

Mushroom lectins have important biological and biomedical applications, most lectins purified from these organisms exhibit high toxicity in animal cells and towards microbial agents. They are able to induce cell growth inhibition and metabolism by their ability to interact with glyconjugate components (glycoproteins receptors, glycolipids) present in their membrane, after their binding to these membrane receptor, they induce cellular signalization chains in which gene expression is regulated and death cell program (apoptosis) is activated. In this work, a new multimeric lectin was characterized from the rare saprobic edible mushroom Laetiporus sulphureus strain TMES43 grown in Algeria forest; lectin was isolated by ammonium sulfate precipitation followed by an affinity chromatography on a sepharose 4B column, with specific activity and respectively yield 1204.7 UHA/mg and 35.55 %. The protein has tetrameric structure with molecular weight of 36 kDa for each subunit, with a total molecular weight approximately of 140 kDa. In addition, Mascote peptide fingerprint study on MALDI-TOF/TOF tandem fragment showed identity with Autophagy-related protein 16 from Meyerozyma guilliermondii (strain ATCC 6260/CBS 566/DSM 6381/JCM 1539/NBRC 10279/NRRL Y-324) (Expasy id: ATG16_PICGU) and no sequence similarity to known mushroom lectins. Its hemagglutination activity was reduced by 5 mM of lactose and 10 mM EDTA incubation, and recovered by metallic cations as CaCl2, MgCl2 and ZnCl2. Laetiporus sulphureus purified lectin (PSLec) hasn't human ABO groups specifity and shows low temperature and alkaline pH stabilities. MTT preliminary assay showed that Laetiporus sulphureus purified lectin