1) The biosynthesis pathway of HA in S. zooepidemicus
The sugar backbone of HA is derived from glucose-6-
phosphate and fructose-6-phosphate. The HA synthesis
pathway can be divided into two sets. In the first set of
reactions, glucose-6-phosphate is converted to glucose-
1-phosphate by a-phosphoglucomutase. UDP-glucose
pyrophosphorylase adds UTP to glucose-1-phosphate to
produce UDP-glucose. Finally, oxidation of the primary
alcohol in UDP-glucose by UDP-glucose dehydrogenase
yields the first HA precursor, UDP-glucuronic acid. In
the second set of reactions, glutamine fructose-6-phosphate
amidotransferase transfers the amido group from
glutamine to fructose-6-phosphate to yield glucosamine-
6-phosphate. Phosphate group rearrangement by phosphoglucosamine
mutase produces glucosamine-1-phosphate.
The acetylated form of this compound is
produced in the next step by phosphoglucosamine acetyltransferase.
Finally N-acetylglucosamine-1-phosphate
pyrophosphorylase activates the intermediate by the
addition of UTP thus yielding the second HA precursor,
UDP-N-acetylglucosamine