Structure of a ubiquitin-loaded HECT ligase reveals the molecular basis for catalytic priming

Nat Struct Mol Biol. 2013 Jun;20(6):696-701. doi: 10.1038/nsmb.2566. Epub 2013 May 5.


Homologous to E6-AP C terminus (HECT) E3 ligases recognize and directly catalyze ligation of ubiquitin (Ub) to their substrates. Molecular details of this process remain unknown. We report the first structure, to our knowledge, of a Ub-loaded E3, the human neural precursor cell-expressed developmentally downregulated protein 4 (Nedd4). The HECT(Nedd4)~Ub transitory intermediate provides a structural basis for the proposed sequential addition mechanism. The donor Ub, transferred from the E2, is bound to the Nedd4 C lobe with its C-terminal tail locked in an extended conformation, primed for catalysis. We provide evidence that the Nedd4-family members are Lys63-specific enzymes whose catalysis is mediated by an essential C-terminal acidic residue.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Crystallography, X-Ray
  • Endosomal Sorting Complexes Required for Transport / chemistry*
  • Endosomal Sorting Complexes Required for Transport / metabolism*
  • Humans
  • Models, Molecular
  • Nedd4 Ubiquitin Protein Ligases
  • Protein Binding
  • Protein Conformation
  • Ubiquitin / chemistry*
  • Ubiquitin / metabolism*
  • Ubiquitin-Protein Ligases / chemistry*
  • Ubiquitin-Protein Ligases / metabolism*


  • Endosomal Sorting Complexes Required for Transport
  • Ubiquitin
  • Nedd4 Ubiquitin Protein Ligases
  • Nedd4 protein, human
  • Ubiquitin-Protein Ligases

Associated data

  • PDB/4BBN
  • PDB/4BE8