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

• Published in: Nature structural & molecular biology Vol. 14; no. 10; pp. 941 - 948
• Main Authors: Klevit, Rachel E, Christensen, Devin E, Brzovic, Peter S
• Format: Journal Article
• Language: English
• Published: United States Nature Publishing Group 01.10.2007
• Subjects: Amino Acid Sequence; BRCA mutations; BRCA1 Protein - genetics; BRCA1 Protein - metabolism; Breast cancer; Enzymes; Humans; Models, Molecular; Molecular Sequence Data; Mutation; Ovarian cancer; Physiological aspects; Polyubiquitin - metabolism; Protein Structure, Quaternary; Proteins; Recombinant Fusion Proteins - chemistry; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; RING Finger Domains; Sequence Alignment; Tumor Suppressor Proteins - genetics; Tumor Suppressor Proteins - metabolism; Two-Hybrid System Techniques; Ubiquitin-Conjugating Enzymes - genetics; Ubiquitin-Conjugating Enzymes - metabolism; Ubiquitin-proteasome system; Ubiquitin-Protein Ligases - genetics; Ubiquitin-Protein Ligases - metabolism; Yeast; Yeasts; United States
• ISSN: 1545-9993; 1545-9985
• DOI: 10.1038/nsmb1295

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.