8pjn
From Proteopedia
Catalytic module of human CTLH E3 ligase bound to multiphosphorylated UBE2H~ubiquitin
Structural highlights
FunctionRMD5A_HUMAN Core component of the CTLH E3 ubiquitin-protein ligase complex that selectively accepts ubiquitin from UBE2H and mediates ubiquitination and subsequent proteasomal degradation of the transcription factor HBP1. MAEA and RMND5A are both required for catalytic activity of the CTLH E3 ubiquitin-protein ligase complex (PubMed:29911972). Catalytic activity of the complex is required for normal cell proliferation (PubMed:29911972). The CTLH E3 ubiquitin-protein ligase complex is not required for the degradation of enzymes involved in gluconeogenesis, such as FBP1 (PubMed:29911972).[1] Publication Abstract from PubMedUbiquitylation is catalyzed by coordinated actions of E3 and E2 enzymes. Molecular principles governing many important E3-E2 partnerships remain unknown, including those for RING-family GID/CTLH E3 ubiquitin ligases and their dedicated E2, Ubc8/UBE2H (yeast/human nomenclature). GID/CTLH-Ubc8/UBE2H-mediated ubiquitylation regulates biological processes ranging from yeast metabolic signaling to human development. Here, cryoelectron microscopy (cryo-EM), biochemistry, and cell biology reveal this exquisitely specific E3-E2 pairing through an unconventional catalytic assembly and auxiliary interactions 70-100 A away, mediated by E2 multisite phosphorylation. Rather than dynamic polyelectrostatic interactions reported for other ubiquitylation complexes, multiple Ubc8/UBE2H phosphorylation sites within acidic CK2-targeted sequences specifically anchor the E2 C termini to E3 basic patches. Positions of phospho-dependent interactions relative to the catalytic domains correlate across evolution. Overall, our data show that phosphorylation-dependent multivalency establishes a specific E3-E2 partnership, is antagonistic with dephosphorylation, rigidifies the catalytic centers within a flexing GID E3-substrate assembly, and facilitates substrate collision with ubiquitylation active sites. Multisite phosphorylation dictates selective E2-E3 pairing as revealed by Ubc8/UBE2H-GID/CTLH assemblies.,Chrustowicz J, Sherpa D, Li J, Langlois CR, Papadopoulou EC, Vu DT, Hehl LA, Karayel O, Beier V, von Gronau S, Muller J, Prabu JR, Mann M, Kleiger G, Alpi AF, Schulman BA Mol Cell. 2023 Dec 8:S1097-2765(23)00972-3. doi: 10.1016/j.molcel.2023.11.027. PMID:38113892[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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