The growth and pathogenesis of Citrobacter rodentium is compromised by disrupted mucin sugar pathways that accumulate N-acetylglucosamine 6-phosphate

Many enteric bacterial pathogens, including the attaching/effacing (A/E) Escherichia coli strains, cause acute gastroenteritis in humans. Considering the highly competitive nature of the mammalian gastrointestinal (GI) tract, these pathogens must rely on specific metabolic adaptations to establish successful infections. We hypothesized that A/E pathogens exploit host-derived nutrients within GI mucus, including the monosaccharides N-acetylglucosamine (GlcNAc) and N-acetylneuraminic acid (NeuNAc) to fuel their pathogenesis. Using Citrobacter rodentium , a murine-specific A/E pathogen , we disrupted both GlcNAc and NeuNAc catabolism by deleting nagA , which encodes the GlcNAc-6-phosphate (GlcNAc-6P) deacetylase that converts GlcNAc-6P into glucosamine-6-phosphate (GlcN-6P). The Δ nagA mutant displayed dramatically impaired colonization in C57BL/6J mice and accumulated significant levels of GlcNAc-6P, unlike the Δ mana strain, a mutant lacking all GlcNAc and NeuNAc transporters, suggesting that the attenuation was due to sugar-phosphate stress rather than nutrient deprivation alone. Supplementation with glucosamine (GlcN) restored growth, indicating that dysregulated GlcN-6P synthesis, rather than GlcNAc-6P toxicity, underlies the defect. Furthermore, Δ nagA exhibited increased susceptibility to several cell wall-dependent stress conditions, in concert with compromised peptidoglycan biosynthesis due to reduced UDP-GlcNAc synthesis. These findings reveal a previously unrecognized metabolic vulnerability in C. rodentium and suggest that targeting sugar-phosphate stress responses may provide a new therapeutic strategy against GI bacterial pathogens.