Mechanism of ubiquitylation by dimeric RING ligase RNF4

Anna Plechanovova, Ellis G. Jaffray, Stephen A. McMahon, Kenneth A. Johnson, Iva Navratilova, James H. Naismith, Ronald T. Hay (Lead / Corresponding author)

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    101 Citations (Scopus)

    Abstract

    Mammalian RNF4 is a dimeric RING ubiquitin E3 ligase that ubiquitylates poly-SUMOylated proteins. We found that RNF4 bound ubiquitin-charged UbcH5a tightly but free UbcH5a weakly. To provide insight into the mechanism of RING-mediated ubiquitylation, we docked the UbcH5 similar to ubiquitin thioester onto the RNF4 RING structure. This revealed that with E2 bound to one monomer of RNF4, the thioester-linked ubiquitin could reach across the dimer to engage the other monomer. In this model, the 'Ile44 hydrophobic patch' of ubiquitin is predicted to engage a conserved tyrosine located at the dimer interface of the RING, and mutation of these residues blocked ubiquitylation activity. Thus, dimeric RING ligases are not simply inert scaffolds that bring substrate and E2-loaded ubiquitin into close proximity. Instead, they facilitate ubiquitin transfer by preferentially binding the E2 similar to ubiquitin thioester across the dimer and activating the thioester bond for catalysis.

    Original languageEnglish
    Pages (from-to)1052-1059
    Number of pages8
    JournalNature Structural & Molecular Biology
    Volume18
    Issue number9
    DOIs
    Publication statusPublished - Sep 2011

    Keywords

    • E3 UBIQUITIN LIGASES
    • SUMO-BINDING MOTIF
    • CRYSTAL-STRUCTURE
    • PROTEINS
    • COMPLEX
    • DIMERIZATION
    • RECOGNITION
    • E2
    • IDENTIFICATION
    • HETERODIMER

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