Recognition of 2-keto-3-deoxyoctonate in bacterial cells and lipopolysaccharides by the sialic acid binding lectin from the horseshoe crab Carcinoscorpius rotunda cauda

Abstract

The sialic acid binding loctin carcinoscorpin agglutinates Escharichia coli K12 and Salmonella minnesots R595 cells. This interaction can be inhibited by the saccharides namely 2-keto-3-deoxyoctonate and the disaccharide D-(N-acetylneuraminyl) (2→6)2-acetamide-2-deoxy-D-galactitol. N-acetylneuraminic acid is shown to be a poor inhibitor. The same behaviour is seen when purified lipopolysaccharides from these two Gram negative bacteria are used. Vibrio cholerae, a Gram negative bacterium devoid of 2-keto-3-deoxyoctonate and Staphylococcus sureus a typical Gram positive bacterium failed to agglutinate in the presence of the lectin. The results suggest that the 2-keto-3-deoxyoctonate residues might represent the physiological substrate for the sialic acid binding lectin from the horseshoe crab.