8q7r
From Proteopedia
Ubiquitin ligation to substrate by a cullin-RING E3 ligase & Cdc34: NEDD8-CUL2-RBX1-ELOB/C-FEM1C with trapped UBE2R2~donor UB-Sil1 peptide
Structural highlights
FunctionCUL2_HUMAN Core component of multiple cullin-RING-based ECS (ElonginB/C-CUL2/5-SOCS-box protein) E3 ubiquitin-protein ligase complexes, which mediate the ubiquitination of target proteins. May serve as a rigid scaffold in the complex and may contribute to catalysis through positioning of the substrate and the ubiquitin-conjugating enzyme. The E3 ubiquitin-protein ligase activity of the complex is dependent on the neddylation of the cullin subunit and is inhibited by the association of the deneddylated cullin subunit with TIP120A/CAND1 (By similarity). The functional specificity of the ECS complex depends on the substrate recognition component. ECS(VHL) mediates the ubiquitination of hypoxia-inducible factor (HIF). Publication Abstract from PubMedCullin-RING ligases (CRLs) ubiquitylate specific substrates selected from other cellular proteins. Substrate discrimination and ubiquitin transferase activity were thought to be strictly separated. Substrates are recognized by substrate receptors, such as Fbox or BCbox proteins. Meanwhile, CRLs employ assorted ubiquitin-carrying enzymes (UCEs, which are a collection of E2 and ARIH-family E3s) specialized for either initial substrate ubiquitylation (priming) or forging poly-ubiquitin chains. We discovered specific human CRL-UCE pairings governing substrate priming. The results reveal pairing of CUL2-based CRLs and UBE2R-family UCEs in cells, essential for efficient PROTAC-induced neo-substrate degradation. Despite UBE2R2's intrinsic programming to catalyze poly-ubiquitylation, CUL2 employs this UCE for geometrically precise PROTAC-dependent ubiquitylation of a neo-substrate and for rapid priming of substrates recruited to diverse receptors. Cryo-EM structures illuminate how CUL2-based CRLs engage UBE2R2 to activate substrate ubiquitylation. Thus, pairing with a specific UCE overcomes E2 catalytic limitations to drive substrate ubiquitylation and targeted protein degradation. Cullin-RING ligases employ geometrically optimized catalytic partners for substrate targeting.,Li J, Purser N, Liwocha J, Scott DC, Byers HA, Steigenberger B, Hill S, Tripathi-Giesgen I, Hinkle T, Hansen FM, Prabu JR, Radhakrishnan SK, Kirkpatrick DS, Reichermeier KM, Schulman BA, Kleiger G Mol Cell. 2024 Apr 4;84(7):1304-1320.e16. doi: 10.1016/j.molcel.2024.01.022. Epub , 2024 Feb 20. PMID:38382526[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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