Isolation, purification and properties of an intermediate in 3-deoxy-D-manno-octulosonic acid--lipid A biosynthesis.
Incomplete lipid A has been purified from a mutant of Salmonella typhimurium which is temperature-sensitive both in synthesis of 3-deoxy-D-manno-octulosonic acid 8-phosphate (dOclA-8-P) and in growth. Pulse-chase experiments have shown that the incomplete lipid A molecule is the intermediate in the biosynthesis of the dOclA-lipid A portion of lipopolysaccharides. The purification procedure included DEAE-cellulose chromatography and electrodialysis. A highly water-soluble precursor material was obtained, consisting of glucosamine, phosphate and 3-hydroxymyristic acid in a molar ratio of 1:1.2:2.1. Labeling experiments as well as chemical degradation procedures revealed the precursor molecule to be composed of a diphosphorylated glucosamine-disaccharide carrying two amide-linked and two ester-linked 3-hydroxymyristic acids. In contrast to the complete dOclA-lipid A part, the intermediate lacks 3-deoxy-D-manno-octulosonic acid as well as nonhydroxylated fatty acids. On the basis of these findings a pathway for the final steps in dOclA-lipid A biosynthesis is proposed.
D000117:Acetylglucosamine / Q000378:metabolism; D005227:Fatty Acids / Q000032:analysis; D006017:Glycolipids / Q000096:biosynthesis*; D007700:Kinetics; D008050:Lipid A / Q000096:biosynthesis* / Q000302:isolation & purification; D008070:Lipopolysaccharides / Q000096:biosynthesis*; D009154:Mutation; D012486:Salmonella typhimurium / Q000378:metabolism*; D013400:Sugar Acids / Q000378:metabolism
D005227:Fatty Acids; D006017:Glycolipids; D008050:Lipid A; D008070:Lipopolysaccharides; D013400:Sugar Acids; D000117:Acetylglucosamine