Identification of UDP-glucose as an intermediate in the biosynthesis of the membrane-derived oligosaccharides of Escherichia coli.
The membrane-derived oligosaccharides of Escherichia coli constitute a closely related family of oligosaccharides containing approximately 9 glucose units variously substituted with sn-glycero-1-phosphate and phosphoethanolamine residues derived from the head groups of membrane phospholipids, and also with succinate in O-ester linkage (Kennedy, E.P., Rumley, M.K., Schulman, H., and van Golder, L.M.G. (1976) J. Biol. Chem. 251, 4208-4213). Studies with mutant strains defective in the synthesis of various nucleoside diphosphate sugars have now revealed that UDP-glucose is an essential intermediate in the biosynthesis of these oligosaccharides. Mutants unable to synthesize UDP-glucose do not contain significant amounts of the membrane-derived oligosaccharides. In contrast, a strain unable to synthesize ADP-glucose, the glucosyl donor for glycogen synthesis in E. coli, contained normal amounts of the membrane-derived oligosaccharides, although with a somewhat different pattern of distribution of the various subspecies. In confirmation of these genetic studies, pulse-label isotope tracer studies have been carried out with glucose of high specific activity, under conditions in which UDP-glucose comprises a large fraction of the total radioactivity in the low molecular weight pool. Subsequent "chase" experiments clearly revealed the conversion of UDP-glucose to the higher molecular weight membrane-derived oligosaccharides.
D002462:Cell Membrane / Q000378:metabolism*; D002852:Chromatography, Ion Exchange; D004926:Escherichia coli / Q000378:metabolism*; D009154:Mutation; D009844:Oligosaccharides / Q000096:biosynthesis*; D005957:UTP-Glucose-1-Phosphate Uridylyltransferase / Q000378:metabolism; D014532:Uridine Diphosphate Glucose / Q000378:metabolism*; D014539:Uridine Diphosphate Sugars / Q000378:metabolism*
D009844:Oligosaccharides; D014539:Uridine Diphosphate Sugars; D005957:UTP-Glucose-1-Phosphate Uridylyltransferase; D014532:Uridine Diphosphate Glucose