Six independent fucose-binding sites in the crystal structure of Aspergillus oryzae lectin

The crystal structure of AOL (a fucose-specific lectin of Aspergillus oryzae) has been solved by SAD (single-wavelength anomalous diffraction) and MAD (multi-wavelength anomalous diffraction) phasing of seleno-fucosides. The overall structure is a six-bladed β-propeller similar to that of other fucose-specific lectins. The fucose moieties of the seleno-fucosides are located in six fucose-binding sites. Although the Arg and Glu/Gln residues bound to the fucose moiety are common to all fucose-binding sites, the amino-acid residues involved in fucose binding at each site are not identical. The varying peak heights of the seleniums in the electron density map suggest that each fucose-binding site has a different carbohydrate binding affinity. •The six-bladed β-propeller structure of AOL was solved by seleno-sugar phasing.•The mode of fucose binding is essentially conserved at all six binding sites.•The seleno-fucosides exhibit slightly different interactions and electron densities.•These findings suggest that the affinity for fucose is not identical at each site.