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COP9 signalosome-specific phosphorylation targets p53 to degradation by the ubiquitin system.

In higher eukaryotic cells, the p53 protein is degraded by the ubiquitin-26S proteasome system mediated by Mdm2 or the human papilloma virus E6 protein. Here we show that COP9 signalosome (CSN)-specific phosphorylation targets human p53 to ubiquitin-26S proteasome-dependent degradation. As visualized by electron microscopy, p53 binds with high affinity to the native CSN complex. p53 interacts via its N-terminus with CSN subunit 5/Jab1 as shown by far-western and pull-down assays. The CSN-specific phosphorylation sites were mapped to the core domain of p53 including Thr155. A phosphorylated peptide, Deltap53(145-164), specifically inhibits CSN-mediated phosphorylation and p53 degradation. Curcumin, a CSN kinase inhibitor, blocks E6-dependent p53 degradation in reticulocyte lysates. Mutation of Thr155 to valine is sufficient to stabilize p53 against E6-dependent degradation in reticulocyte lysates and to reduce binding to Mdm2. The p53T155V mutant accumulates in both HeLa and HL 60 cells and exhibits a mutant (PAb 240+) conformation. It induces the cyclin-dependent inhibitor p21. In HeLa and MCF-7 cells, inhibition of CSN kinase by curcumin or Deltap53(145-164) results in accumulation of endogenous p53.

Pubmed ID: 11285227


  • Bech-Otschir D
  • Kraft R
  • Huang X
  • Henklein P
  • Kapelari B
  • Pollmann C
  • Dubiel W


The EMBO journal

Publication Data

April 2, 2001

Associated Grants


Mesh Terms

  • Amino Acid Sequence
  • Binding Sites
  • DNA
  • DNA-Binding Proteins
  • HL-60 Cells
  • HeLa Cells
  • Humans
  • Intracellular Signaling Peptides and Proteins
  • Molecular Sequence Data
  • Multiprotein Complexes
  • Mutagenesis, Site-Directed
  • Peptide Hydrolases
  • Phosphorylation
  • Proteasome Endopeptidase Complex
  • Proteins
  • Proto-Oncogene Proteins p21(ras)
  • Signal Transduction
  • Threonine
  • Transcription Factors
  • Tumor Suppressor Protein p53
  • Ubiquitins
  • Valine