Hydroxyproline-rich bacterial agglutinin from potato : extraction, purification, and characterization

A protein, extracted from Katahdin potato (Solanum tuberosum L. cv `Katahdin') tubers and purified by ion exchange chromatography and gel filtration, agglutinates avirulent strains of the bacterial wilt pathogen, Pseudomonas solanacearum, but only weakly agglutinates virulent strains. The agglutinin has very low hemagglutinating activity (in contrast to potato lectin) and is a glycoprotein containing about 61% carbohydrate. The carbohydrate moiety contains 91% (weight%) arabinose, 5% galactose, 3% glucose, and 1% glucosamine. The protein portion is rich in hydroxyproline (42%), lysine (16%), serine (9%), and proline (9%). The entire agglutinin has a molecular weight of 91,000 ± 5,000 and is very basic (pI > 11). Shape estimations based on the concentration dependence of the sedimentation coefficient, the high viscosity (η] = 92.7), the frictional coefficient (f/f_o = 2.15), and axial ratio (a/b = 25) indicate that the agglutinin is a prolate ellipsoid.