E2-BRCA1 RING interactions dictate synthesis of mono- or specific polyubiquitin chain linkages

Nat Struct Mol Biol. 2007 Oct;14(10):941-8. doi: 10.1038/nsmb1295. Epub 2007 Sep 16.

Abstract

An E3 ubiquitin ligase mediates the transfer of activated ubiquitin from an E2 ubiquitin-conjugating enzyme to its substrate lysine residues. Using a structure-based, yeast two-hybrid strategy, we discovered six previously unidentified interactions between the human heterodimeric RING E3 BRCA1-BARD1 and the human E2s UbcH6, Ube2e2, UbcM2, Ubc13, Ube2k and Ube2w. All six E2s bind directly to the BRCA1 RING motif and are active with BRCA1-BARD1 for autoubiquitination in vitro. Four of the E2s direct monoubiquitination of BRCA1. Ubc13-Mms2 and Ube2k direct the synthesis of Lys63- or Lys48-linked ubiquitin chains on BRCA1 and require an acceptor ubiquitin attached to BRCA1. Differences between the mono- and polyubiquitination activities of the BRCA1-interacting E2s correlate with their ability to bind ubiquitin noncovalently at a site distal to the active site. Thus, BRCA1 has the ability to direct the synthesis of specific polyubiquitin chain linkages, depending on the E2 bound to its RING.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • BRCA1 Protein / genetics
  • BRCA1 Protein / metabolism*
  • Humans
  • Models, Molecular
  • Molecular Sequence Data
  • Polyubiquitin / metabolism*
  • Protein Structure, Quaternary
  • RING Finger Domains*
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Sequence Alignment
  • Tumor Suppressor Proteins / genetics
  • Tumor Suppressor Proteins / metabolism
  • Two-Hybrid System Techniques
  • Ubiquitin-Conjugating Enzymes / genetics
  • Ubiquitin-Conjugating Enzymes / metabolism*
  • Ubiquitin-Protein Ligases / genetics
  • Ubiquitin-Protein Ligases / metabolism

Substances

  • BRCA1 Protein
  • BRCA1 protein, human
  • Recombinant Fusion Proteins
  • Tumor Suppressor Proteins
  • Polyubiquitin
  • Ubiquitin-Conjugating Enzymes
  • BARD1 protein, human
  • Ubiquitin-Protein Ligases