Lipid-bound saccharides in Rhizobium meliloti

Abstract

The lipid-bound saccharides formed by incubation of uridine diphosphate glucose with a particulate enzyme of Rhizobium meliloti were studied. They behaved like polyprenyl diphosphate saccharides when treated with ammonia or hot phenol, when catalytically hydrogenated, and on DEAE-cellulose chromatography. The saccharide moieties obtained after heating at pH 2 for 10 min at 100 degrees C were separated with a gel filtration column. The following compounds were detected: galactose, glucosyl beta 1-3 galactose (Tolmasky, M. E., Staneloni, R. J., Ugalde, R. A., and Leloir, L. F. (1980) ARch. Biochem. Biophys. 203, 358-364), and some octasaccharides (I). These were compared by paper electrophoresis, thin layer and paper chromatography with an octasaccharide obtained from Alcaligenes faecalis var. myxogenes strain 11 (II). Furthermore, Compounds I and II were compared with the exopolysaccharide of Rhizobium meliloti (III) by partial acid hydrolysis and methylation analysis. The results were consistent with the identity of the repeating unit of Compound III with Compounds I and II except for differences in the substituents (acetyl or succinyl). Studies on the labeling of the lipid-bound saccharides have shown that the sequence is: first, galactose and glucosyl beta 1-3 galactose, then the rest of glucose residues, and finally, the substituents (acetyl and pyruvic acid).