Structure of E3 ligase E6AP with a proteasome-binding site provided by substrate receptor hRpn10.
Regulated proteolysis by proteasomes involves ~800 enzymes for substrate modification with ubiquitin, including ~600 E3 ligases. We report here that E6AP/UBE3A is distinguished from other E3 ligases by having a 12?nM binding site at the proteasome contributed by substrate receptor hRpn10/PSMD4/S5a. Intrinsically disordered by itself, and previously uncharacterized, the E6AP-binding ... domain in hRpn10 locks into a well-defined helical structure to form an intermolecular 4-helix bundle with the E6AP AZUL, which is unique to this E3. We thus name the hRpn10 AZUL-binding domain RAZUL. We further find in human cells that loss of RAZUL by CRISPR-based gene editing leads to loss of E6AP at proteasomes. Moreover, proteasome-associated ubiquitin is reduced following E6AP knockdown or displacement from proteasomes, suggesting that E6AP ubiquitinates substrates at or for the proteasome. Altogether, our findings indicate E6AP to be a privileged E3 for the proteasome, with a dedicated, high affinity binding site contributed by hRpn10.
Mesh Terms:
Binding Sites, HCT116 Cells, Humans, Models, Biological, Models, Molecular, Proteasome Endopeptidase Complex, Protein Binding, Protein Domains, Protein Structure, Secondary, RNA-Binding Proteins, Substrate Specificity, Ubiquitin-Protein Ligases
Binding Sites, HCT116 Cells, Humans, Models, Biological, Models, Molecular, Proteasome Endopeptidase Complex, Protein Binding, Protein Domains, Protein Structure, Secondary, RNA-Binding Proteins, Substrate Specificity, Ubiquitin-Protein Ligases
Nat Commun
Date: Dec. 10, 2019
PubMed ID: 32157086
View in: Pubmed Google Scholar
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