Structural characterization of the nonameric assembly of an Archaeal alpha-L-fucosidase by synchrotron small angle X-ray scattering.

alpha-l-Fucosidase is a lysosomal enzyme responsible for hydrolyzing the alpha-1,6-linked fucose joined to the reducing-end N-acetylglucosamine of carbohydrate moieties in glycoproteins. The first alpha-l-fucosidase from Archaea was recently identified in the genome of the hyperthermophile Sulfolobus solfataricus; the enzyme is encoded by two open reading frames separated by a -1 frameshift. A preliminary biochemical and biophysical characterization of this extremophile enzyme has been carried out both in solution, through small angle X-ray scattering experiments, and in the crystalline state, showing an unusual oligomeric assembly resulting from the association of nine subunits, endowed with 3-fold molecular symmetry.