Synthesis of Lipopolysaccharides

Synthesis of Lipopolysaccharides

Synthesis of Lipopolysaccharides - The cytoplasmic membrane contains all the enzymes required for the assembly of lipopolysaccharides.

Biosynthesis is sequential. It starts with the lipid A portion which is synthesized by the addition of the fatty acids and KDO to the glucosamine disaccharide.

The core oligosaccharide is extended on lipid A, and the 0 side-chain is built up on the core oligosaccharide.

Extension of the chain takes place by the addition of successive sugar units, each catalysed by a specific transferase from a nucleosidediphosphate sugar.

The repeating side chain unit is synthesized on the inner face of the plasma membrane.

It is made by successive transfer from: nucleoside diphosphate-sugars on a carrier undecaprenol-P (Und-P).

Polymerization then takes place on the outer face of the membrane.

Each repeat unit is synthesized by tail addition.

The completed unit is then incorporated by head addition. i. e. the growing polymer is transferred from its carrier to the next carrier attached unit.

When the chain reaches appropriate length, it is transferred to the free end of a core chain.

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