Carbohydrate mediation of the biological activities of the glycolipoprotein of Pseudomonas aeruginosa.

The glycolipoprotein (GLP) extracted from the surface slime of Pseudomonas aeruginosa produces effects in mice similar to those of the viable cell. The lethal activity has been located in the lipid moiety; however, degradation of the carbohydrate moiety with sodium metaperiodate reduced the antigenicity and abolished the lethality of the GLP. Similar degradation with a phage-induced polysaccharide depolymerase reduced the antigenicity only slightly but reduced the lethality over 60%. The neutral sugar composition of the isolated polysaccharide moiety was shown to be that of the parental GLP. Of the component neutral sugars, mannose and its derivatives were capable of inhibiting the agglutination of erythrocytes coated with GLP. Inhibition also occurred with a soluble mannose polymer from the cell walls of yeast. Antiserum to GLP and to its isolated polysaccharide moiety agglutinated yeast cells, whereas antiserum to a glycolipid fragment of the GLP lacking mannose did not. The lethality of the GLP was reduced by degradation with alpha-mannosidase or by blocking the mannose residues with concanavalin A, and the glycolipid fragment showed less lethality than the native GLP. We conclude that mannose, in addition to being an immunodominant sugar, is an effector sugar in the expression of GLP lethality.