Bacterial pathogens have evolved distinct ways of colonizing host cells and promote infection. Many human intestinal bacterial pathogens such as Salmonella, Shigella and enteropathogenic/ enterohemorrhagic Escherichia coli utilize type III secretion systems to deliver virulence effector proteins into the host to promote colonization and interfere with antimicrobial host response. Among the type III effectors, the NleB protein has been shown to be essential for virulence of enteric pathogens. NleB is a glycosyltransferase that has been shown to interact with host cell death-domain-containing proteins, GlcNAcylate a specific arginine on these and thereby inhibiting death receptor signalling and preventing host cell apoptosis. This proposal will 1) investigate how NleB specifically recognises the host death domains, 2) uncover the molecular mechanisms of arginine GlcNAcylation, 3) explain how death domain GlcNAcylation prevents the death domain from binding to its receptor, and 4) exploit this molecular information to generate bisubstrate inhibitors to interfere with this process.