FIGURE 1.

Bacterial degradation and metabolism of glycosaminoglycans. Glycosaminoglycans (e.g. hyaluronan and heparin) are depolymerized by lyase, and the resultant unsaturated disaccharides are subsequently degraded to unsaturated uronic acids and amino sugars by UGL. Unsaturated glucuronic/iduronic acids are nonenzymatically converted into Dhu. Dhu is metabolized to pyruvate (Pyr) and glyceraldehyde-3-phosphate (G-3-P) through the subsequent reactions of four enzymes (i.e. isomerase (DhuI or KduI), dehydrogenase (DhuD or KduD), kinase (KdgK), and aldolase (KdgA)). GlcNAc, N-acetylglucosamine; DK-II, 3-deoxy-d-glycero-2,5-hexodiulosonate; KDGP, 2-keto-3-deoxy-6-phosphogluconate. Dhu is also generated from pectin via unsaturated galacturonic acid (ΔGalUA).