Colanic acid building blocks biosynthesis (Saccharomyces cerevisiae)

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Colanic acid (or M antigen) is a type of extracellular polysaccharide. It consists of a polyanionic heteropolysaccharide that contains a nonstoichiometric combination of sugars such as D-glucose, L-fucoses, D-galactose, and D-glucuronate, which are decorated with O-acetyl and pyruvate side chains. Before assembly, the sugars must be activated in the form of nucleotide sugars. The process of assembling the colanic acid polysaccharide repeat takes place on the membrane lipid through a series of glycosyl transferases on the cytoplasmic side of the inner membrane. Once the single repeat is assembled, it is flipped to the periplasmic side and polymerized by the Wzy-dependent pathway.