Unified Theory of Bacterial Sialometabolism: How and Why Bacteria Metabolize Host Sialic Acids
Figure 12
Known or proposed functions of the E. coli sialoregulon. Wavy lines indicate mucin peptide backbones with idealized O-linked (serine/threonine) oligosaccharides composed of GalNAc (bold circle); GlcNAc (open squares); Gal (open circles); Neu5Ac (open diamonds, indicating the alpha anomer while hatched diamonds represent the thermodynamically favored beta anomer). Neu5Ac derivatives: acetyl (Ac) groups indicated by their linkages to different Neu5Ac carbon position (numbers in diamonds); Neu5,9Ac2, Neu5,7Ac2, Neu5,8Ac2, Neu4,5Ac2, Neu5,7,9Ac3, Neu5,8,9Ac3, and Neu5Gc (diamond with OH) is Neu5Ac with hydroxyl at position 5 (see Figure 1), Lt (lactyl), Me (methy). Bold diamond is neuraminic acid (Neu, which lacks the carbon-5 acetamido group). Triangle represents ADOA while diamond with horizontal line represents Neu5Ac1,7L (see Figures 3(b) and 3(c)). Diamond with cross lines represents Neu5Ac2en (see Figure 3(d)). Other abbreviations are as given in the legend to Figure 7.
