PMID: 6989835May 10, 1980Paper

Biosynthesis of lipid A. Formation of acyl-deficient lipopolysaccharides in Salmonella typhimurium and Escherichia coli.

The Journal of Biological Chemistry
R W Walenga, M J Osborn

Abstract

The effect of cerulenin on conversion of an acyl-deficient precursor of lipid A to lipopolysaccharide was investigated in a mutant of Salmonella typhimurium (PRX22H9) conditionally defective in synthesis of 3-deoxy-D-mannooctulosonate (KDO). The precursor lacks both KDO and the saturated O-fatty acyl chains of lipopolysaccharide and contains beta-hydroxymyristate as sole fatty acid. Concentrations of cerulenin which inhibited de novo synthesis of fatty acids and lipopolysaccharide more than 95% had no effect on the rate or extent of conversion of preformed lipid A precursor to a lipopolysaccharide product. The product was identified as a polymer containing the Rc type core polysaccharide of PRX22H9 linked to the acyl-deficient lipid A unit of the precursor. The acyl-deficient lipopolysaccharide was translocated to the outer membrane at a normal rate. Lipopolysaccharide deficient in saturated fatty acids was also produced by a fabD mutant of Escherichia coli under conditions of limited endogenous fatty acid synthesis. The results indicate that prior incorporation of the saturated O-acyl chains of lipid A is not necessary for extension of the core polysaccharide chain and that synthesis of underacylated lipopolysaccharides occurs...Continue Reading

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