DDI2 Is a Ubiquitin-Directed Endoprotease Responsible for Cleavage of Transcription Factor NRF1

A. Barbara Dirac-Svejstrup, Jane Walker, Peter Faull, Vesela Encheva, Vyacheslav Akimov, Michele Puglia, David Perkins, Sandra Kümper, Suchete S. Hunjan, Blagoy Blagoev, Ambrosius P. Snijders, David J. Powell, Jesper Q. Svejstrup*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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The Ddi1/DDI2 proteins are ubiquitin shuttling factors, implicated in a variety of cellular functions. In addition to ubiquitin-binding and ubiquitin-like domains, they contain a conserved region with similarity to retroviral proteases, but whether and how DDI2 functions as a protease has remained unknown. Here, we show that DDI2 knockout cells are sensitive to proteasome inhibition and accumulate high-molecular weight, ubiquitylated proteins that are poorly degraded by the proteasome. These proteins are targets for the protease activity of purified DDI2. No evidence for DDI2 acting as a de-ubiquitylating enzyme was uncovered, which could suggest that it cleaves the ubiquitylated protein itself. In support of this idea, cleavage of transcription factor NRF1 is known to require DDI2 activity in vivo. We show that DDI2 is indeed capable of cleaving NRF1 in vitro but only when NRF1 protein is highly poly-ubiquitylated. Together, these data suggest that DDI2 is a ubiquitin-directed endoprotease.

Original languageEnglish
JournalMolecular Cell
Issue number2
Pages (from-to)332-341.e7
Publication statusPublished - 9. Jun 2020


  • Bortezomib
  • Ddi1
  • DDI2
  • NFE2L1
  • NRF1
  • proteasome
  • proteasome inhibition
  • ubiquitin
  • ubiquitin protease


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