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Structure of HECT E3 UBR5 forming K48 linked Ubiquitin chainsStructure of HECT E3 UBR5 forming K48 linked Ubiquitin chains
Structural highlights
Publication Abstract from PubMedUbiquitin (Ub) chain formation by homologous to E6AP C-terminus (HECT)-family E3 ligases regulates vast biology, yet the structural mechanisms remain unknown. We used chemistry and cryo-electron microscopy (cryo-EM) to visualize stable mimics of the intermediates along K48-linked Ub chain formation by the human E3, UBR5. The structural data reveal a approximately 620 kDa UBR5 dimer as the functional unit, comprising a scaffold with flexibly tethered Ub-associated (UBA) domains, and elaborately arranged HECT domains. Chains are forged by a UBA domain capturing an acceptor Ub, with its K48 lured into the active site by numerous interactions between the acceptor Ub, manifold UBR5 elements and the donor Ub. The cryo-EM reconstructions allow defining conserved HECT domain conformations catalyzing Ub transfer from E2 to E3 and from E3. Our data show how a full-length E3, ubiquitins to be adjoined, E2 and intermediary products guide a feed-forward HECT domain conformational cycle establishing a highly efficient, broadly targeting, K48-linked Ub chain forging machine. Structural snapshots along K48-linked ubiquitin chain formation by the HECT E3 UBR5.,Hehl LA, Horn-Ghetko D, Prabu JR, Vollrath R, Vu DT, Perez Berrocal DA, Mulder MPC, van der Heden van Noort GJ, Schulman BA Nat Chem Biol. 2024 Feb;20(2):190-200. doi: 10.1038/s41589-023-01414-2. Epub 2023 , Aug 24. PMID:37620400[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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