Activation of the IkappaB kinase complex by TRAF6 requires a dimeric ubiquitin-conjugating enzyme complex and a unique polyubiquitin chain

Cell. 2000 Oct 13;103(2):351-61. doi: 10.1016/s0092-8674(00)00126-4.

Abstract

TRAF6 is a signal transducer in the NF-kappaB pathway that activates IkappaB kinase (IKK) in response to proinflammatory cytokines. We have purified a heterodimeric protein complex that links TRAF6 to IKK activation. Peptide mass fingerprinting analysis reveals that this complex is composed of the ubiquitin conjugating enzyme Ubc13 and the Ubc-like protein Uev1A. We find that TRAF6, a RING domain protein, functions together with Ubc13/Uev1A to catalyze the synthesis of unique polyubiquitin chains linked through lysine-63 (K63) of ubiquitin. Blockade of this polyubiquitin chain synthesis, but not inhibition of the proteasome, prevents the activation of IKK by TRAF6. These results unveil a new regulatory function for ubiquitin, in which IKK is activated through the assembly of K63-linked polyubiquitin chains.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Biopolymers / metabolism*
  • Cell-Free System
  • Cloning, Molecular
  • Dimerization
  • Enzyme Activation
  • HeLa Cells
  • Humans
  • I-kappa B Kinase
  • Ligases / isolation & purification
  • Ligases / metabolism*
  • Molecular Sequence Data
  • Peptide Mapping
  • Polyubiquitin
  • Protein-Serine-Threonine Kinases / metabolism*
  • Proteins / metabolism*
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  • TNF Receptor-Associated Factor 6
  • Transcription Factors*
  • Ubiquitin-Conjugating Enzymes
  • Ubiquitin-Protein Ligases
  • Ubiquitins / metabolism*

Substances

  • Biopolymers
  • Proteins
  • TNF Receptor-Associated Factor 6
  • Transcription Factors
  • Ubiquitins
  • Polyubiquitin
  • UBE2V1 protein, human
  • Ubiquitin-Conjugating Enzymes
  • Ubiquitin-Protein Ligases
  • Protein-Serine-Threonine Kinases
  • CHUK protein, human
  • I-kappa B Kinase
  • IKBKB protein, human
  • IKBKE protein, human
  • Ligases

Associated data

  • GENBANK/AY008273