Salmonella Effectors SseK1 and SseK3 Target Death Domain Proteins in the TNF and TRAIL Signaling Pathways

Mol Cell Proteomics. 2019 Jun;18(6):1138-1156. doi: 10.1074/mcp.RA118.001093. Epub 2019 Mar 22.


Strains of Salmonella utilize two distinct type three secretion systems to deliver effector proteins directly into host cells. The Salmonella effectors SseK1 and SseK3 are arginine glycosyltransferases that modify mammalian death domain containing proteins with N-acetyl glucosamine (GlcNAc) when overexpressed ectopically or as recombinant protein fusions. Here, we combined Arg-GlcNAc glycopeptide immunoprecipitation and mass spectrometry to identify host proteins GlcNAcylated by endogenous levels of SseK1 and SseK3 during Salmonella infection. We observed that SseK1 modified the mammalian signaling protein TRADD, but not FADD as previously reported. Overexpression of SseK1 greatly broadened substrate specificity, whereas ectopic co-expression of SseK1 and TRADD increased the range of modified arginine residues within the death domain of TRADD. In contrast, endogenous levels of SseK3 resulted in modification of the death domains of receptors of the mammalian TNF superfamily, TNFR1 and TRAILR, at residues Arg376 and Arg293 respectively. Structural studies on SseK3 showed that the enzyme displays a classic GT-A glycosyltransferase fold and binds UDP-GlcNAc in a narrow and deep cleft with the GlcNAc facing the surface. Together our data suggest that salmonellae carrying sseK1 and sseK3 employ the glycosyltransferase effectors to antagonise different components of death receptor signaling.

Keywords: Bacteria; Cell death*; Glycosylation; Infectious disease; Inflammation; Inflammatory response; Salmonella; SseK; Virulence; death receptor signaling; glycosyltransferase.

MeSH terms

  • Acetylglucosamine / metabolism
  • Animals
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism*
  • Conserved Sequence
  • Glutamic Acid / metabolism
  • Glycosylation
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Mice
  • Mice, Inbred C57BL
  • Mutagenesis
  • Mutation / genetics
  • Protein Domains
  • RAW 264.7 Cells
  • Receptors, TNF-Related Apoptosis-Inducing Ligand / metabolism
  • Receptors, Tumor Necrosis Factor, Type I / metabolism
  • Salmonella / metabolism*
  • Signal Transduction*
  • Substrate Specificity
  • TNF Receptor-Associated Death Domain Protein / chemistry
  • TNF Receptor-Associated Death Domain Protein / metabolism
  • TNF-Related Apoptosis-Inducing Ligand / metabolism*
  • Tumor Necrosis Factor-alpha / metabolism*


  • Bacterial Proteins
  • Receptors, TNF-Related Apoptosis-Inducing Ligand
  • Receptors, Tumor Necrosis Factor, Type I
  • TNF Receptor-Associated Death Domain Protein
  • TNF-Related Apoptosis-Inducing Ligand
  • Tumor Necrosis Factor-alpha
  • Glutamic Acid
  • Acetylglucosamine

Associated data

  • PDB/6CGI
  • PDB/6DUS
  • PDB/3SRZ
  • PDB/1FOA