Purification and characterization of a mycelial mucin specific lectin from Aspergillus panamensis with potent mitogenic and antibacterial activity

A lectin was isolated from Aspergillus panamensis mycelia using single-step affinity chromatography on porcine stomach mucin coupled Sepharose 4B. A purification fold of 19.2 with 62.5% yield was achieved by this method. Gel filtration chromatography showed the native molecular mass of 78 kDa and the subunit molecular mass of 39 kDa was confirmed by 10% SDS-PAGE and MALDI-TOF analysis. Isoelectric focussing of native A. panamensis lectin revealed it to be an acidic protein with p14.5. Carbohydrate content of purified lectin was estimated to be 4.95%. All database search of N-terminal amino acid sequences revealed no homology of the purified lectin with previously reported microbial, viral and animal lectins except 29 kDa subunit of heterodimeric Vigna sesquipedalis lectin. The lectin from this fungal source is a homodimer. Lectin was fairly thermostable with pH optima of 6.5-8.0 and had no requirement of divalent metal cations for its activity. Maximum mitogenic activity toward mouse spleen cells was exhibited at 100 mu g/mL concentration of purified lectin. Results of the antimicrobial assay showed that the lectin had potent antibacterial activity against Bacillus cereus, Staphylococcous aureus, Pseudomonas aeruginosa and Escherichia coli. (C) 2015 Elsevier Ltd. All rights reserved.