Bifunctional phosphomannose isomerase/GDP-D-mannose pyrophosphorylase is the point of control for GDP-D-mannose biosynthesis in Helicobacter pylori.

In this report a recombinant bifunctional phosphomannose isomerase/GDP-D-mannose pyrophosphorylase from Helicobacter pylori has been studied. The enzyme catalyzes the first and third steps of GDP-D-mannose biosynthesis from D-fructose-6-phosphate. The first step, isomerization from D-fructose-6-phosphate to D-mannose-6-phosphate, is found to be rate-limiting in GDP-D-mannose biosynthesis due to feedback inhibition. The inhibition is of non-competitive (mixed) type. As the enzyme is found only in bacteria probably participating in capsular polysaccharide biosynthesis, it could be a specific therapeutic target against bacterial infection.