OTULIN antagonizes LUBAC signaling by specifically hydrolyzing Met1-linked polyubiquitin

Cell. 2013 Jun 6;153(6):1312-26. doi: 10.1016/j.cell.2013.05.014.

Abstract

The linear ubiquitin (Ub) chain assembly complex (LUBAC) is an E3 ligase that specifically assembles Met1-linked (also known as linear) Ub chains that regulate nuclear factor κB (NF-κB) signaling. Deubiquitinases (DUBs) are key regulators of Ub signaling, but a dedicated DUB for Met1 linkages has not been identified. Here, we reveal a previously unannotated human DUB, OTULIN (also known as FAM105B), which is exquisitely specific for Met1 linkages. Crystal structures of the OTULIN catalytic domain in complex with diubiquitin reveal Met1-specific Ub-binding sites and a mechanism of substrate-assisted catalysis in which the proximal Ub activates the catalytic triad of the protease. Mutation of Ub Glu16 inhibits OTULIN activity by reducing kcat 240-fold. OTULIN overexpression or knockdown affects NF-κB responses to LUBAC, TNFα, and poly(I:C) and sensitizes cells to TNFα-induced cell death. We show that OTULIN binds LUBAC and that overexpression of OTULIN prevents TNFα-induced NEMO association with ubiquitinated RIPK1. Our data suggest that OTULIN regulates Met1-polyUb signaling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Catalysis
  • Crystallography, X-Ray
  • Cytokines / metabolism
  • Endopeptidases / chemistry*
  • Endopeptidases / genetics
  • Endopeptidases / metabolism*
  • Humans
  • Models, Molecular
  • Molecular Sequence Data
  • Polyubiquitin / biosynthesis
  • Protein Structure, Tertiary
  • Sequence Alignment
  • Signal Transduction

Substances

  • Cytokines
  • Polyubiquitin
  • Endopeptidases
  • gumby protein, human

Associated data

  • PDB/3ZNV
  • PDB/3ZNX
  • PDB/3ZNZ