An interaction network of the mammalian COP9 signalosome identifies Dda1 as a core subunit of multiple Cul4-based E3 ligases

J Cell Sci. 2009 Apr 1;122(Pt 7):1035-44. doi: 10.1242/jcs.043539.


The COP9 signalosome (CSN) is an evolutionarily conserved macromolecular complex that interacts with cullin-RING E3 ligases (CRLs) and regulates their activity by hydrolyzing cullin-Nedd8 conjugates. The CSN sequesters inactive CRL4(Ddb2), which rapidly dissociates from the CSN upon DNA damage. Here we systematically define the protein interaction network of the mammalian CSN through mass spectrometric interrogation of the CSN subunits Csn1, Csn3, Csn4, Csn5, Csn6 and Csn7a. Notably, we identified a subset of CRL complexes that stably interact with the CSN and thus might similarly be activated by dissociation from the CSN in response to specific cues. In addition, we detected several new proteins in the CRL-CSN interactome, including Dda1, which we characterized as a chromatin-associated core subunit of multiple CRL4 proteins. Cells depleted of Dda1 spontaneously accumulated double-stranded DNA breaks in a similar way to Cul4A-, Cul4B- or Wdr23-depleted cells, indicating that Dda1 interacts physically and functionally with CRL4 complexes. This analysis identifies new components of the CRL family of E3 ligases and elaborates new connections between the CRL and CSN complexes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • COP9 Signalosome Complex
  • Cell Cycle
  • Cell Line
  • Chromatin / metabolism
  • Cullin Proteins / metabolism*
  • DNA-Binding Proteins / metabolism*
  • Humans
  • Mammals / metabolism*
  • Multiprotein Complexes / metabolism*
  • Peptide Hydrolases / metabolism*
  • Protein Binding
  • Protein Subunits / metabolism*
  • Protein Transport
  • Proteome / metabolism
  • Ubiquitin-Protein Ligases / metabolism*


  • CUL4A protein, human
  • CUL4B protein, human
  • Chromatin
  • Cullin Proteins
  • DDA1 protein, human
  • DNA-Binding Proteins
  • Multiprotein Complexes
  • Protein Subunits
  • Proteome
  • Ubiquitin-Protein Ligases
  • Peptide Hydrolases
  • COP9 Signalosome Complex