title: Biosynthesis of T1 antigen in Salmonella: origin of D-galactofuranose and D-ribofuranose residues.
abstract: The "T1 side chain" portion of cell wall lipopolysaccharide from T1 strains of Salmonella contains d-galactofuranose and d-ribofuranose residues. Isotope labeling studies, using intact cells of mutants each blocked at either of the two different steps of d-galactose metabolism (uridine diphosphate-glucose 4-epimerase and galactose-1-P uridylyl transferase) or at phosphoglucoisomerase, led to the following conclusions. (i) d-Galactofuranose residues are synthesized from d-galactopyranose or its derivatives, rather than by a direct conversion from other hexopyranoses or their derivatives. (ii) The pyranose-to-furanose conversion does not appear to take place at the level of the free d-galactose or d-galactose 1-phosphate. This result suggests that the conversion may occur at the stage of uridine diphosphate-d-galactose. (iii) In a mutant lacking phosphoglucoisomerase, d-ribofuranose residues in T1 side chains contained (14)C derived from exogenous d-fructose-U-(14)C, but little (3)H from exogenous d-glucose-1-(3)H. Thus, no evidence was found for a direct pathway of aldohexose-to-ribose conversion involving a loss of one of the carbons in the C2-C6 moiety of aldohexoses. This suggests, but does not prove, that the T1 ribofuranose residues are synthesized by conventional mechanisms involving hexose monophosphate shunt and transketolase-transaldolase reactions.
mesh_terms: D000941:Antigens / Q000032:analysis / Q000302:isolation & purification; D001089:Arabinose / Q000378:metabolism; D002247:Carbon Isotopes; D055598:Chemical Phenomena; D002621:Chemistry; D002854:Chromatography, Paper; D003227:Conjugation, Genetic; D003470:Culture Media; D003956:Dialysis; D005690:Galactose / Q000378:metabolism; D007535:Isomerases / Q000378:metabolism; D008070:Lipopolysaccharides / Q000032:analysis / Q000096:biosynthesis* / Q000302:isolation & purification; D009154:Mutation; D009713:Nucleotidyltransferases / Q000378:metabolism; D010636:Phenols; D010770:Phosphotransferases / Q000378:metabolism; D011995:Recombination, Genetic; D012266:Ribose / Q000378:metabolism; D012486:Salmonella typhimurium / Q000201:enzymology / Q000254:growth & development / Q000276:immunology / Q000378:metabolism*; D012997:Solvents; D014316:Tritium
chemical_list: D000941:Antigens; D002247:Carbon Isotopes; D003470:Culture Media; D008070:Lipopolysaccharides; D010636:Phenols; D012997:Solvents; D014316:Tritium; D012266:Ribose; D001089:Arabinose; D010770:Phosphotransferases; D009713:Nucleotidyltransferases; D007535:Isomerases; D005690:Galactose