Targeting a helix-in-groove interaction between E1 and E2 blocks ubiquitin transfer

Nat Chem Biol. 2020 Nov;16(11):1218-1226. doi: 10.1038/s41589-020-0625-7. Epub 2020 Aug 17.


The ubiquitin-proteasome system (UPS) is a highly regulated protein disposal process critical to cell survival. Inhibiting the pathway induces proteotoxic stress and can be an effective cancer treatment. The therapeutic window observed upon proteasomal blockade has motivated multiple UPS-targeting strategies, including preventing ubiquitination altogether. E1 initiates the cascade by transferring ubiquitin to E2 enzymes. A small molecule that engages the E1 ATP-binding site and derivatizes ubiquitin disrupts enzymatic activity and kills cancer cells. However, binding-site mutations cause resistance, motivating alternative approaches to block this promising target. We identified an interaction between the E2 N-terminal alpha-1 helix and a pocket within the E1 ubiquitin-fold domain as a potentially druggable site. Stapled peptides modeled after the E2 alpha-1 helix bound to the E1 groove, induced a consequential conformational change and inhibited E1 ubiquitin thiotransfer, disrupting E2 ubiquitin charging and ubiquitination of cellular proteins. Thus, we provide a blueprint for a distinct E1-targeting strategy to treat cancer.

Publication types

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

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Amino Acid Sequence
  • Binding Sites
  • Cell Line, Tumor
  • Drug Design
  • Drug Resistance, Neoplasm
  • Humans
  • Molecular Conformation
  • Molecular Docking Simulation
  • Peptides / chemistry
  • Proteasome Endopeptidase Complex / metabolism*
  • Protein Binding
  • Structure-Activity Relationship
  • Ubiquitin / chemistry
  • Ubiquitin / genetics
  • Ubiquitin / metabolism*
  • Ubiquitin-Activating Enzymes / metabolism*
  • Ubiquitination


  • Peptides
  • UBA1 protein, human
  • Ubiquitin
  • Adenosine Triphosphate
  • Proteasome Endopeptidase Complex
  • UBA7 protein, human
  • Ubiquitin-Activating Enzymes