A promiscuous alpha-helical motif anchors viral hijackers and substrate receptors to the CUL4-DDB1 ubiquitin ligase machinery

Nat Struct Mol Biol. 2010 Jan;17(1):105-11. doi: 10.1038/nsmb.1719. Epub 2009 Dec 6.


The cullin 4-DNA-damage-binding protein 1 (CUL4-DDB1) ubiquitin ligase machinery regulates diverse cellular functions and can be subverted by pathogenic viruses. Here we report the crystal structure of DDB1 in complex with a central fragment of hepatitis B virus X protein (HBx), whose DDB1-binding activity is important for viral infection. The structure reveals that HBx binds DDB1 through an alpha-helical motif, which is also found in the unrelated paramyxovirus SV5-V protein despite their sequence divergence. Our structure-based functional analysis suggests that, like SV5-V, HBx captures DDB1 to redirect the ubiquitin ligase activity of the CUL4-DDB1 E3 ligase. We also identify the alpha-helical motif shared by these viral proteins in the cellular substrate-recruiting subunits of the E3 complex, the DDB1-CUL4-associated factors (DCAFs) that are functionally mimicked by the viral hijackers. Together, our studies reveal a common yet promiscuous structural element that is important for the assembly of cellular and virally hijacked CUL4-DDB1 E3 complexes.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Western
  • Colony-Forming Units Assay
  • Crystallization
  • Cullin Proteins / metabolism*
  • DNA-Binding Proteins / chemistry*
  • DNA-Binding Proteins / metabolism*
  • Green Fluorescent Proteins
  • HeLa Cells
  • Humans
  • Immunoprecipitation
  • Luciferases
  • Models, Molecular*
  • Protein Binding
  • Protein Structure, Secondary*
  • Trans-Activators / chemistry*
  • Trans-Activators / metabolism
  • Two-Hybrid System Techniques
  • Ubiquitin-Protein Ligases / metabolism
  • Viral Regulatory and Accessory Proteins


  • CUL4A protein, human
  • Cullin Proteins
  • DDB1 protein, human
  • DNA-Binding Proteins
  • Trans-Activators
  • Viral Regulatory and Accessory Proteins
  • hepatitis B virus X protein
  • Green Fluorescent Proteins
  • Luciferases
  • Ubiquitin-Protein Ligases

Associated data

  • PDB/3I7H
  • PDB/3I7K
  • PDB/3I7L
  • PDB/3I7N
  • PDB/3I7O
  • PDB/3I7P
  • PDB/3I89
  • PDB/3I8C
  • PDB/3I8E