NleB, a Bacterial Effector with Glycosyltransferase Activity, Targets GADPH Function to Inhibit NF-κB Activation

Modulation of NF-kappa B-dependent responses is critical to the success of attaching/effacing (NE) human pathogenic E. coli (EPEC and EHEC) and the natural mouse pathogen Citrobacter rodentium. NleB, a highly conserved type III secretion system effector of NE pathogens, suppresses NF-kappa B activation, but the underlying mechanisms are unknown. We identified the mammalian glycolysis enzyme glyceraldehyde 3-phosphate dehydrogenase (GAPDH) as an NleB-interacting protein. Further, we discovered that GAPDH interacts with the TNF receptor-associated factor 2 (TRAF2), a protein required for TNF-alpha-mediated NF-kappa B activation, and regulates TRAF2 polyubiquitination. During infection, NleB functions as a translocated N-acetyl-D-glucosamine (O-GlcNAc) transferase that modifies GAPDH. NleB-mediated GAPDH O-GlcNAcylation disrupts the TRAF2-GAPDH interaction to suppress TRAF2 polyubiquitination and NF-kappa B activation. Eliminating NleB O-GlcNAcylation activity attenuates C. rodentium colonization of mice. These data identify GAPDH as a TRAF2 signaling cofactor and reveal a virulence strategy employed by NE pathogens to inhibit NF-kappa B-dependent host innate immune responses.