Abstract
The tumour necrosis factor (TNF) family is crucial for immune homeostasis, cell death and inflammation. These cytokines are recognized by members of the TNF receptor (TNFR) family of death receptors, including TNFR1 and TNFR2, and FAS and TNF-related apoptosis-inducing ligand (TRAIL) receptors. Death receptor signalling requires death-domain-mediated homotypic/heterotypic interactions between the receptor and its downstream adaptors, including TNFR1-associated death domain protein (TRADD) and FAS-associated death domain protein (FADD). Here we discover that death domains in several proteins, including TRADD, FADD, RIPK1 and TNFR1, were directly inactivated by NleB, an enteropathogenic Escherichia coli (EPEC) type III secretion system effector known to inhibit host nuclear factor-κB (NF-κB) signalling. NleB contained an unprecedented N-acetylglucosamine (GlcNAc) transferase activity that specifically modified a conserved arginine in these death domains (Arg 235 in the TRADD death domain). NleB GlcNAcylation (the addition of GlcNAc onto a protein side chain) of death domains blocked homotypic/heterotypic death domain interactions and assembly of the oligomeric TNFR1 complex, thereby disrupting TNF signalling in EPEC-infected cells, including NF-κB signalling, apoptosis and necroptosis. Type-III-delivered NleB also blocked FAS ligand and TRAIL-induced cell death by preventing formation of a FADD-mediated death-inducing signalling complex (DISC). The arginine GlcNAc transferase activity of NleB was required for bacterial colonization in the mouse model of EPEC infection. The mechanism of action of NleB represents a new model by which bacteria counteract host defences, and also a previously unappreciated post-translational modification.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Acylation
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Animals
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Apoptosis
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Arginine / metabolism*
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Death Domain Receptor Signaling Adaptor Proteins / metabolism
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Disease Models, Animal
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Enteropathogenic Escherichia coli / metabolism*
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Enteropathogenic Escherichia coli / pathogenicity
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Escherichia coli Infections / metabolism
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Escherichia coli Infections / microbiology
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Escherichia coli Infections / pathology
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Escherichia coli Proteins / metabolism*
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Fas-Associated Death Domain Protein / chemistry
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Fas-Associated Death Domain Protein / metabolism
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HeLa Cells
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Humans
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Male
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Mice
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Mice, Inbred C57BL
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Multiprotein Complexes / chemistry
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Multiprotein Complexes / metabolism
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N-Acetylglucosaminyltransferases / metabolism*
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NF-kappa B / metabolism
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Protein Biosynthesis
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Protein Structure, Tertiary
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Receptor-Interacting Protein Serine-Threonine Kinases / chemistry
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Receptor-Interacting Protein Serine-Threonine Kinases / metabolism
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Receptors, Tumor Necrosis Factor, Type I / chemistry
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Receptors, Tumor Necrosis Factor, Type I / metabolism
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Signal Transduction*
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TNF Receptor-Associated Death Domain Protein / chemistry*
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TNF Receptor-Associated Death Domain Protein / metabolism*
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TNF-Related Apoptosis-Inducing Ligand / metabolism
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Tumor Necrosis Factor-alpha / metabolism
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Virulence
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Virulence Factors / metabolism*
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fas Receptor / metabolism
Substances
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Death Domain Receptor Signaling Adaptor Proteins
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Escherichia coli Proteins
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Fas-Associated Death Domain Protein
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Multiprotein Complexes
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NF-kappa B
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NleB protein, E coli
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Receptors, Tumor Necrosis Factor, Type I
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TNF Receptor-Associated Death Domain Protein
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TNF-Related Apoptosis-Inducing Ligand
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Tumor Necrosis Factor-alpha
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Virulence Factors
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fas Receptor
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Arginine
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N-Acetylglucosaminyltransferases
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RIPK1 protein, human
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Receptor-Interacting Protein Serine-Threonine Kinases