Characterization of the 41kDa allergen Asp v 13, a subtilisin-like serine protease from Aspergillus versicolor

Aspergillus versicolor is common on moldy building materials. Asp v 13, the principal allergen is produced by strains collected from across Canada. In this paper, we report a 1833bp Asp v 13 open reading frame predicted to encode a protein of 403 amino acids in length with three introns. A BLAST search of Asp v 13, a phylogenic tree calculation and alignment with its homologous proteins from other species indicated that Asp v 13 is a secretory, subtilisin-like serine protease widely distributed in Aspergillus species. His-tagged Asp v 13 was over-expressed in Escherichia coli and purified using Ni-NTA columns with a yield of 1mg/L. Based on immuno binding assay of recombinant protein both antibodies developed against the natural protein, and human sera IgE, the recombinant protein was similar to the natural form. Six IgE- and seven IgG-binding epitopes were also identified with selected human sera along the entire amino acid sequence of Asp v 13. Most residues binding these epitopes are exposed on the surface and correspond to charged regions of the molecule.