Role of C-terminal region of HA-33 component of botulinum toxin in hemagglutination

Using SDS-PAGE, we found that one subcomponent, hemagglutinin (HA-33), from the Clostridium botulinum progenitor toxin of type D strain 1873 and type C strain Yoichi had slightly smaller molecular sizes than those of type C a nd D reference strains, but other components did not. Based on N- and C-ter minal sequence analyses of HA-33, a deletion of 31 amino acid residues from the C-terminus at a specific site was observed in the HA-33 proteins of bo th strains. The progenitor toxins from both strains showed poor hemagglutin ation activities, titers of 2(1) or less, which were much lower than titers from the reference strains (2(6)), and did not bind to erythrocytes. These results suggest strongly that the short C-terminal region of the HA-33 pla ys an essential role in the hemagglutination activity of the botulinum. pro genitor toxin. Additionally, a sequence motif search predicted that the C-t erminal region of HA-33 has a carbohydrate-recognition sub-domain. (C) 2001 Academic Press.