Fig. 1. The proposed catabolic pathway for GlcNAc1A in this study and reported catabolic pathways for GlcNAc and N-acetyl-D-serine.

Catabolism of GlcNAc is initiated by phosphorylation by a GlcNAc kinase (e.g. in Shewanella oneidensis¹¹) or a PTS (e.g. in Vibrionaceae^8,40), which is subsequently deacetylated and deaminated to produce fructose-6-P. Catabolism of N-acetyl-D-serine in some bacteria starts with deacetylation followed by deamination and formation of pyruvate^44,54. In the proposed catabolic pathway for GlcNAc1A in this study, GlcNAc1A is deacetylated and deaminated directly to produce KDG without activation by phosphorylation. As such, this GlcNAc1A degradation pathway resembles N-acetyl-D-amino acid catabolism through deacetylation and deamination. Enzymes involved in catabolic pathways for GlcNAc1A, GlcNAc and N-acetyl-D-serine are shown in red, blue and green, respectively. The protein families of enzymes involved in each pathway are indicated in parentheses. PTS phosphotransferase, GlcN D-glucosamine, PLP pyridoxal 5-phosphate, KDG 2-keto-3-deoxygluconate.