Arginine-GlcNAcylation of death domain and NleB/SseK proteins is crucial for bacteria pathogenesis by regulating host cell death

Death receptor signaling is critical for cell death, inflammation, and immune homeostasis. Hijacking death receptors and their corresponding adaptors through type III secretion system (T3SS) effectors has been evolved to be a bacterial evasion strategy. NleB from enteropathogenic Escherichia coli(EPEC) and SseK1/2/3 from Salmonella enterica serovar Typhimurium (S. Typhimurium) can modify some death domains involved in death receptor signaling through arginine-GlcNAcylation. This study applied a limited substrate screen from 12 death domain proteins with conserved arginines during EPEC and Salmonella infection and found that NleB from EPEC hijacked death receptor signaling tumor necrosis factor receptor 1 (TNFR1)-associated death domain protein (TRADD), FAS-associated death domain protein (FADD), and receptor-interacting serine/threonine-protein kinase 1 (RIPK1), whereas SseK1 and SseK3 disturbed TNFR signaling through the modification of TRADD Arg235/245 and TNFR1 Arg376, respectively. SseK1 and SseK3 delivered by Salmonella inhibited TNF-α- but not TNF-related apoptosis-inducing ligand (TRAIL)-induced cell death, which was consistent with their host substrate recognition specificity. Taking advantage of the substrate specificity of SseK effectors, we found that only SseK1 fully rescued the bacteria colonization deficiency contributed by NleBc in Citrobacter rodentium infection animal model, indicating that TRADD was likely to be the preferred in vivo substrate corresponding to NleB/SseK1-induced bacterial virulence. Furthermore, novel auto-arginine-GlcNAcylation was observed in NleB and SseK1/3, which promoted the enzyme activity. These findings suggest that arginine-GlcNAcylation in death domains and auto-arginine-GlcNAcylation catalyzed by type III-translocated bacterial effector proteins NleB/SseKs are crucial for bacteria pathogenesis in regulating nuclear factor-κB (NF-κB) and death receptor signaling pathways. This study provides an insight into the mechanism by which EPEC and Salmonella manipulate death receptor signaling and evade host immune defense through T3SS effectors.