PROPERTIES OF O-SPECIFIC HAPTEN FORMED IN VIVO BY MUTANT STRAINS OF SALMONELLA TYPHIMURIUM

The isolation and separation of two polymers each containing sugars characteristic of O-antigen in Salmonella typhimurium have shown that mutant strains blocked in synthesis of the core moiety of lipopolysaccharide accumulate significant amounts of O- specific hapten. In contrast, cultures of wild-type cells or wild-type phenocopies incorporate the bulk of O-specific moieties into lipopolysaccharide and contain only minor amounts of hapten. Although both O-specific polymers are firmly bound to the particulate cell envelope fraction and, in general, are similarly distributed among the subcellular fractions, experiments with intact mutant cells show that the haptenic polymer is not on the outer surface of the cell. Treatment with EDTA or with EDTA plus lysozyme exposes the hapten as judged by a significant increase in adsorption of O-specific phage by these cells. After phenol extraction of intact cells, the hapten was separated from lipopolysaccharide by differential ethanol precipitation, by chromatography on DEAE-cellulose columns, by centrifugation at 105,000g, and by equilibrium sedimentation in CsCl density gradients. Its properties are identical with those previously described for the O-specific hapten synthesized enzymatically: (1) galactose 1-phosphate is the reducing terminus; (2) average degree of polymerization is about 30; (3) characteristic oligosaccharides are recovered after partial acid hydrolysis. Both polymers are precipitated by anti-O antiserum and each competes with the other for precipitation. © 1968, American Chemical Society. All rights reserved.