4qpl | pdb_00004qpl
Crystal structure of RNF146(RING-WWE)/UbcH5a/iso-ADPr complex
Structural highlights
Function[RN146_MOUSE] E3 ubiquitin-protein ligase that specifically binds poly-ADP-ribosylated (PARsylated) proteins and mediates their ubiquitination and subsequent degradation. May regulate many important biological processes, such as cell survival and DNA damage response. Acts as an activator of the Wnt signaling pathway by mediating the ubiquitination of PARsylated AXIN1 and AXIN2, 2 key components of the beta-catenin destruction complex. Acts in cooperation with tankyrase proteins (TNKS and TNKS2), which mediate PARsylation of target proteins AXIN1, AXIN2, BLZF1, CASC3, TNKS and TNKS2. Recognizes and binds tankyrase-dependent PARsylated proteins via its WWE domain and mediates their ubiquitination (By similarity). May regulate TNKS and TNKS2 subcellular location, preventing aggregation at a centrosomal location. Neuroprotective protein. Protects the brain against N-methyl-D-aspartate (NMDA) receptor-mediated glutamate excitotoxicity and ischemia, by interfering with PAR-induced cell death, called parthanatos. Prevents nuclear translocation of AIFM1 in a PAR-binding dependent manner. Does not affect PARP1 activation (By similarity). Protects against cell death induced by DNA damaging agents, such as N-methyl-N-nitro-N-nitrosoguanidine (MNNG) and rescues cells from G1 arrest. Promotes cell survival after gamma-irradiation. Facilitates DNA repair. Neuroprotective protein. Protects the brain against N-methyl-D-aspartate (NMDA) receptor-mediated glutamate excitotoxicity and ischemia, by interfering with PAR-induced cell death, called parthanatos. Prevents nuclear translocation of AIFM1 in a PAR-binding dependent manner. Does not affect PARP1 activation.[1] [2] [UB2D1_HUMAN] Accepts ubiquitin from the E1 complex and catalyzes its covalent attachment to other proteins. In vitro catalyzes 'Lys-48'-linked polyubiquitination. Mediates the selective degradation of short-lived and abnormal proteins. Functions in the E6/E6-AP-induced ubiquitination of p53/TP53. Mediates ubiquitination of PEX5 and auto-ubiquitination of STUB1, TRAF6 and TRIM63/MURF1. Ubiquitinates STUB1-associated HSP90AB1 in vitro. Lacks inherent specificity for any particular lysine residue of ubiquitin. Essential for viral activation of IRF3. Mediates polyubiquitination of CYP3A4.[3] [4] [5] [6] [7] Publication Abstract from PubMedProtein poly(ADP-ribosyl)ation (PARylation) has a role in diverse cellular processes such as DNA repair, transcription, Wnt signalling, and cell death. Recent studies have shown that PARylation can serve as a signal for the polyubiquitination and degradation of several crucial regulatory proteins, including Axin and 3BP2 (refs 7, 8, 9). The RING-type E3 ubiquitin ligase RNF146 (also known as Iduna) is responsible for PARylation-dependent ubiquitination (PARdU). Here we provide a structural basis for RNF146-catalysed PARdU and how PARdU specificity is achieved. First, we show that iso-ADP-ribose (iso-ADPr), the smallest internal poly(ADP-ribose) (PAR) structural unit, binds between the WWE and RING domains of RNF146 and functions as an allosteric signal that switches the RING domain from a catalytically inactive state to an active one. In the absence of PAR, the RING domain is unable to bind and activate a ubiquitin-conjugating enzyme (E2) efficiently. Binding of PAR or iso-ADPr induces a major conformational change that creates a functional RING structure. Thus, RNF146 represents a new mechanistic class of RING E3 ligases, the activities of which are regulated by non-covalent ligand binding, and that may provide a template for designing inducible protein-degradation systems. Second, we find that RNF146 directly interacts with the PAR polymerase tankyrase (TNKS). Disruption of the RNF146-TNKS interaction inhibits turnover of the substrate Axin in cells. Thus, both substrate PARylation and PARdU are catalysed by enzymes within the same protein complex, and PARdU substrate specificity may be primarily determined by the substrate-TNKS interaction. We propose that the maintenance of unliganded RNF146 in an inactive state may serve to maintain the stability of the RNF146-TNKS complex, which in turn regulates the homeostasis of PARdU activity in the cell. Allosteric activation of the RNF146 ubiquitin ligase by a poly(ADP-ribosyl)ation signal.,DaRosa PA, Wang Z, Jiang X, Pruneda JN, Cong F, Klevit RE, Xu W Nature. 2014 Oct 19. doi: 10.1038/nature13826. PMID:25327252[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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