Cysteine Methylation Disrupts Ubiquitin-Chain Sensing in NF-κB Activation

Nature. 2011 Dec 11;481(7380):204-8. doi: 10.1038/nature10690.

Abstract

NF-κB is crucial for innate immune defence against microbial infection. Inhibition of NF-κB signalling has been observed with various bacterial infections. The NF-κB pathway critically requires multiple ubiquitin-chain signals of different natures. The question of whether ubiquitin-chain signalling and its specificity in NF-κB activation are regulated during infection, and how this regulation takes place, has not been explored. Here we show that human TAB2 and TAB3, ubiquitin-chain sensory proteins involved in NF-κB signalling, are directly inactivated by enteropathogenic Escherichia coli NleE, a conserved bacterial type-III-secreted effector responsible for blocking host NF-κB signalling. NleE harboured an unprecedented S-adenosyl-l-methionine-dependent methyltransferase activity that specifically modified a zinc-coordinating cysteine in the Npl4 zinc finger (NZF) domains in TAB2 and TAB3. Cysteine-methylated TAB2-NZF and TAB3-NZF (truncated proteins only comprising the NZF domain) lost the zinc ion as well as the ubiquitin-chain binding activity. Ectopically expressed or type-III-secretion-system-delivered NleE methylated TAB2 and TAB3 in host cells and diminished their ubiquitin-chain binding activity. Replacement of the NZF domain of TAB3 with the NleE methylation-insensitive Npl4 NZF domain resulted in NleE-resistant NF-κB activation. Given the prevalence of zinc-finger motifs and activation of cysteine thiol by zinc binding, methylation of zinc-finger cysteine might regulate other eukaryotic pathways in addition to NF-κB signalling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / chemistry
  • Adaptor Proteins, Signal Transducing / metabolism*
  • Bacterial Secretion Systems
  • Cysteine / metabolism*
  • Enteropathogenic Escherichia coli / metabolism
  • Enteropathogenic Escherichia coli / pathogenicity
  • Escherichia coli Proteins / metabolism*
  • Humans
  • Intracellular Signaling Peptides and Proteins / chemistry
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • MAP Kinase Kinase Kinases / metabolism
  • Methionine / analogs & derivatives
  • Methionine / metabolism
  • Methylation
  • Methyltransferases / metabolism
  • NF-kappa B / antagonists & inhibitors*
  • NF-kappa B / metabolism*
  • Protein Binding
  • Protein Structure, Tertiary
  • Signal Transduction
  • Substrate Specificity
  • TNF Receptor-Associated Factor 6
  • Tumor Necrosis Factor Receptor-Associated Peptides and Proteins / metabolism
  • Ubiquitin / metabolism*
  • Virulence Factors / metabolism*
  • Zinc Fingers

Substances

  • Adaptor Proteins, Signal Transducing
  • Bacterial Secretion Systems
  • Escherichia coli Proteins
  • Intracellular Signaling Peptides and Proteins
  • NF-kappa B
  • NleE protein, E coli
  • TAB2 protein, human
  • TAB3 protein, human
  • TNF Receptor-Associated Factor 6
  • Tumor Necrosis Factor Receptor-Associated Peptides and Proteins
  • Ubiquitin
  • Virulence Factors
  • Methionine
  • Methyltransferases
  • MAP Kinase Kinase Kinases
  • MAP kinase kinase kinase 7
  • Cysteine