Abstract
RING and U-box E3 ubiquitin ligases regulate diverse eukaryotic processes and have been implicated in numerous diseases, but targeting these enzymes remains a major challenge. We report the development of three ubiquitin variants (UbVs), each binding selectively to the RING or U-box domain of a distinct E3 ligase: monomeric UBE4B, phosphorylated active CBL, or dimeric XIAP. Structural and biochemical analyses revealed that UbVs specifically inhibited the activity of UBE4B or phosphorylated CBL by blocking the E2∼Ub binding site. Surprisingly, the UbV selective for dimeric XIAP formed a dimer to stimulate E3 activity by stabilizing the closed E2∼Ub conformation. We further verified the inhibitory and stimulatory functions of UbVs in cells. Our work provides a general strategy to inhibit or activate RING/U-box E3 ligases and provides a resource for the research community to modulate these enzymes.
Original language | English |
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Pages (from-to) | 456-470.e10 |
Number of pages | 26 |
Journal | Molecular Cell |
Volume | 68 |
Issue number | 2 |
DOIs | |
Publication status | Published - 19 Oct 2017 |
Keywords
- Drug Discovery/methods
- Enzyme Activators/chemistry
- Enzyme Inhibitors/chemistry
- HEK293 Cells
- HeLa Cells
- Humans
- Protein Multimerization/drug effects
- Tumor Suppressor Proteins/agonists
- Ubiquitin-Protein Ligase Complexes/antagonists & inhibitors
- Ubiquitin-Protein Ligases
- X-Linked Inhibitor of Apoptosis Protein/agonists