Molecular characterization of AfuFleA, an l-fucose-specific lectin from Aspergillus fumigatus

Aspergillus fumigatus causes life-threatening infections in immunocompromised patients. We have found that extracts of mycelial mats of A. fumigatus contain a potent hemagglutinin. To clarify the characteristics of this factor, the hemagglutinin was purified from late-stage cultures and characterized at the molecular level. The hemagglutinin is a 32-kilodalton protein that shows activity as an l-fucose lectin. The gene encoding this protein, AfufleA, was identified from a genomic DNA library utilizing consensus primers designed for amino acid sequences obtained from peptides following limited trypsin proteolysis. An open reading frame was found that consists of 942 nucleotides encoding 314 amino acids with a deduced molecular mass of 34,498 and contains all seven of trypsin-digested peptide sequences; four short introns, 49-63 bp, were also identified. AfufleA shares homology with a fucose-specific lectin produced by the orange peel mushroom, Aleuria aurantia. The role of AfufleA fucose-specific lectin is not clear, but this lectin may enhance attachment of fungal spores to mammalian cell membranes and contribute to the pathogenicity of A. fumigatus.