Biosynthesis of a galactose-and galacturonic acid-containing polysaccharide in Rhizobium meliloti.
Previous work showed that two different strains derived from a culture of Rhizobium meliloti 102F51 differed with respect to phage specificity, agglutinability by alfalfa seed lectin, and synthesis of a galactose-containing polysaccharide (R. A. Ugalde, H. Handelsman, and W. J. Brill, J. Bacteriol. 166:148-154, 1986). Inner membranes from the more competitive strain incorporated galactose from UDP-galactose when a thermostable factor was present. This factor has now been identified as UDP-galacturonic acid. UDP-glucuronic acid was also active as a donor; however, this activity may be due to the presence of a 4-epimerase. Galacturonic acid, together with galactose, is incorporated into the reaction product, which appears to be a polysaccharide formed by several repeating units of these two monosaccharides. Partial acid hydrolysis liberates the disaccharide with galactose at the reducing end.
D005690:Galactose / Q000032:analysis / Q000378:metabolism*; D006603:Hexuronic Acids / Q000032:analysis / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D011135:Polysaccharides, Bacterial / Q000032:analysis / Q000096:biosynthesis*; D012231:Rhizobium / Q000378:metabolism*; D013696:Temperature; D014539:Uridine Diphosphate Sugars / Q000032:analysis / Q000378:metabolism*; D014574:Uronic Acids / Q000378:metabolism*
D006603:Hexuronic Acids; D011135:Polysaccharides, Bacterial; D014539:Uridine Diphosphate Sugars; D014574:Uronic Acids; C007819:galacturonic acid; C050306:UDP-galacturonic acid; D005690:Galactose