Glucosylation of lipopolysaccharide in Salmonella: biosynthesis of O antigen factor 12 2 . 3. The presence of 12 2 determinants in haptenic polysaccharides.

Abstract Salmonella mutants defective in the biosynthesis of the central "R core" portion of cell wall lipopolysaccharide accumulate the peripheral "O side chain" portion of lipopolysaccharide in a form presumably linked to the lipid carrier. When such an O side chain polysaccharide was isolated from a core-defective mutant derived from a Salmonella typhimurium strain originally producing O antigen 122, the polysaccharide was found to possess the full determinant group for 122 antigen, i.e. short side chains each consisting of a single α-d-glucopyranosyl residue linked to C-4 of d-galactose. However, the galactose residue at the reducing end of the O side chain did not appear to have been glucosylated. These results suggest that the transfer of the foregoing glucose residues normally takes place at the level of the carrier-linked oligomers of O side chain-repeating units, rather than at the level of the repeating unit monomers or at that of the lipopolysaccharide.