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Mms2-Ubc13 covalently bound to ubiquitin reveals the structural basis of linkage-specific polyubiquitin chain formation.

Lys63-linked polyubiquitin chains participate in nonproteolytic signaling pathways, including regulation of DNA damage tolerance and NF-kappaB activation. E2 enzymes bound to ubiquitin E2 variants (UEV) are vital in these pathways, synthesizing Lys63-linked polyubiquitin chains, but how these complexes achieve specificity for a particular lysine linkage has been unclear. We have determined the crystal structure of an Mms2-Ubc13-ubiquitin (UEV-E2-Ub) covalent intermediate with donor ubiquitin linked to the active site residue of Ubc13. In the structure, the unexpected binding of a donor ubiquitin of one Mms2-Ubc13-Ub complex to the acceptor-binding site of Mms2-Ubc13 in an adjacent complex allows us to visualize at atomic resolution the molecular determinants of acceptor-ubiquitin binding. The structure reveals the key role of Mms2 in allowing selective insertion of Lys63 into the Ubc13 active site and suggests a molecular model for polyubiquitin chain elongation.

Pubmed ID: 16980971


  • Eddins MJ
  • Carlile CM
  • Gomez KM
  • Pickart CM
  • Wolberger C


Nature structural & molecular biology

Publication Data

October 5, 2006

Associated Grants

  • Agency: NIGMS NIH HHS, Id: GM60372

Mesh Terms

  • Binding Sites
  • Models, Molecular
  • Polyubiquitin
  • Protein Binding
  • Protein Structure, Quaternary
  • Protein Structure, Tertiary
  • Saccharomyces cerevisiae Proteins
  • Structure-Activity Relationship
  • Ubiquitin
  • Ubiquitin-Conjugating Enzymes
  • Ubiquitin-Protein Ligases