FIGURE 10.

Schematic diagram showing the biosynthetic steps for R. leguminosarum bv. viciae LPS and indicating the order by which the GalA residues are added to the lipid A and core oligosaccharide. The LPS core backbone is built off of the lipid A on the cytosolic side of the innermembrane and is flipped to the periplasmic side of the innermembrane where the transmembrane Rgt proteins transfer GalA from the lipid donor Dod-P-GalA to the LPS (1). The LPS is transported to the outer membrane where the oxidase LpxQ oxidizes the proximal GlcN to GlcNonate. The Rgt proteins are labeled 1–4 to signify the predicted order of GalA addition. LpcA, -B, and -C = glycosyl transferases, rgtA, -B, -C, -D, and -E = GalA transferases. The boxed region shows the synthesis of Dod-P-GalA from UDP-GalA by RgtE.