8c07

Publication Abstract from PubMed

Ubiquitin (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.