7un3 | pdb_00007un3
Complex of UBE2O with NAP1L1 and ubiquitylated uL2
Structural highlights
Function[RL40_HUMAN] Ubiquitin exists either covalently attached to another protein, or free (unanchored). When covalently bound, it is conjugated to target proteins via an isopeptide bond either as a monomer (monoubiquitin), a polymer linked via different Lys residues of the ubiquitin (polyubiquitin chains) or a linear polymer linked via the initiator Met of the ubiquitin (linear polyubiquitin chains). Polyubiquitin chains, when attached to a target protein, have different functions depending on the Lys residue of the ubiquitin that is linked: Lys-6-linked may be involved in DNA repair; Lys-11-linked is involved in ERAD (endoplasmic reticulum-associated degradation) and in cell-cycle regulation; Lys-29-linked is involved in lysosomal degradation; Lys-33-linked is involved in kinase modification; Lys-48-linked is involved in protein degradation via the proteasome; Lys-63-linked is involved in endocytosis, DNA-damage responses as well as in signaling processes leading to activation of the transcription factor NF-kappa-B. Linear polymer chains formed via attachment by the initiator Met lead to cell signaling. Ubiquitin is usually conjugated to Lys residues of target proteins, however, in rare cases, conjugation to Cys or Ser residues has been observed. When polyubiquitin is free (unanchored-polyubiquitin), it also has distinct roles, such as in activation of protein kinases, and in signaling.[1] [2] Ribosomal protein L40 is a component of the 60S subunit of the ribosome.[3] [4] [UBE2O_HUMAN] E2/E3 hybrid ubiquitin-protein ligase that displays both E2 and E3 ligase activities and mediates monoubiquitination of target proteins (PubMed:23455153, PubMed:24703950). Negatively regulates TRAF6-mediated NF-kappa-B activation independently of its E2 activity (PubMed:23381138). Acts as a positive regulator of BMP7 signaling by mediating monoubiquitination of SMAD6, thereby regulating adipogenesis (PubMed:23455153). Mediates monoubiquitination at different sites of the nuclear localization signal (NLS) of BAP1, leading to cytoplasmic retention of BAP1. Also able to monoubiquitinate the NLS of other chromatin-associated proteins, such as INO80 and CXXC1, affecting their subcellular location (PubMed:24703950). Acts as a regulator of retrograde transport by assisting the TRIM27:MAGEL2 E3 ubiquitin ligase complex to mediate 'Lys-63'-linked ubiquitination of WASHC1, leading to promote endosomal F-actin assembly (PubMed:23452853).[5] [6] [7] [8] [RL8_HUMAN] Publication Abstract from PubMedThe E2/E3 enzyme UBE2O ubiquitylates diverse clients to mediate important processes, including targeting unassembled 'orphan' proteins for quality control and clearing ribosomes during erythropoiesis. How quality-control factors, such as UBE2O, select clients on the basis of heterogeneous features is largely unknown. Here, we show that UBE2O client selection is regulated by ubiquitin binding and a cofactor, NAP1L1. Attaching a single ubiquitin onto a client enhances UBE2O binding and multi-mono-ubiquitylation. UBE2O also repurposes the histone chaperone NAP1L1 as an adapter to recruit a subset of clients. Cryo-EM structures of human UBE2O in complex with NAP1L1 reveal a malleable client recruitment interface that is autoinhibited by the intrinsically reactive UBC domain. Adding a ubiquitylated client identifies a distinct ubiquitin-binding SH3-like domain required for client selection. Our findings reveal how multivalency and a feed-forward mechanism drive the selection of protein quality-control clients. Mechanism of client selection by the protein quality-control factor UBE2O.,Yip MCJ, Sedor SF, Shao S Nat Struct Mol Biol. 2022 Aug;29(8):774-780. doi: 10.1038/s41594-022-00807-6., Epub 2022 Aug 1. PMID:35915257[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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