The Biosynthesis of Cell Wall Lipopolysaccharide in Escherichia coli

An acidic component of the cell wall lipopolysaccharide ofEscherichia coli 0111-B 4 was isolated from mild acid hydrolysates of the polymer.It was concluded that this compound was 3-deoxy-D-manno-octulosonic acid on the basis of the following criteria: (a) paper chromatography in a variety of solvent systems; (b) degradation with ceric sulfate following borohydride reduction; (c) enzymatic degradation by 3-deoxyoctulosonate (KDO) aldolase to yield pyruvate and D-arabinose; (d) the rate of liberation of -formyl pyruvate by periodate oxidation; (e) chemical synthesis of crystalline penta-O-acetyl-KDO methyl ester, which, upon alkaline saponification, yielded KDO which corresponded chromatographically to KDO from lipopolysaccharide.Further, the product of saponification was identical with natural KDO with regard to the specificities of cytidine 5'-phosphate-KDO synthetase and KDO aldolase.The procedure employed for the chemical synthesis of KDO provides a method for the preparation of a chemically pure standard of this compound.The complex lipopolysaccharide of the cell wall of Escherichia coli 0111-B 4 consists of a lipid portion containing hexosamine, organic phosphate, and fatty acids, and a polysaccharide portion, containing heptose, O-phosphorylethanolamine, organic phosphate, glucose, galactose, N-acetylglucosamine, and colitose ( 3 ,6-dideoxy-L-xylohexose) (1).In a preliminary communica-