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SUMO modification of the ubiquitin-conjugating enzyme E2-25K.

Post-translational modification with small ubiquitin-related modifier (SUMO) alters the function of many proteins, but the molecular mechanisms and consequences of this modification are still poorly defined. During a screen for novel SUMO1 targets, we identified the ubiquitin-conjugating enzyme E2-25K (Hip2). SUMO attachment severely impairs E2-25K ubiquitin thioester and unanchored ubiquitin chain formation in vitro. Crystal structures of E2-25K(1-155) and of the E2-25K(1-155)-SUMO conjugate (E2-25K(*)SUMO) indicate that SUMO attachment interferes with E1 interaction through its location on the N-terminal helix. The SUMO acceptor site in E2-25K, Lys14, does not conform to the consensus site found in most SUMO targets (PsiKXE), and functions only in the context of an alpha-helix. In contrast, adjacent SUMO consensus sites are modified only when in unstructured peptides. The demonstration that secondary structure elements are part of SUMO attachment signals could contribute to a better prediction of SUMO targets.

Pubmed ID: 15723079


  • Pichler A
  • Knipscheer P
  • Oberhofer E
  • van Dijk WJ
  • K├Ârner R
  • Olsen JV
  • Jentsch S
  • Melchior F
  • Sixma TK


Nature structural & molecular biology

Publication Data

March 3, 2005

Associated Grants


Mesh Terms

  • Amino Acid Sequence
  • Consensus Sequence
  • Crystallization
  • HeLa Cells
  • Humans
  • Molecular Sequence Data
  • Protein Interaction Mapping
  • Protein Processing, Post-Translational
  • Protein Structure, Secondary
  • SUMO-1 Protein
  • Ubiquitin-Conjugating Enzymes