5ywr
From Proteopedia
Crystal Structure of RING E3 ligase ZNRF1 in complex with Ube2N (Ubc13)
Structural highlights
Function[UBE2N_HUMAN] The UBE2V1-UBE2N and UBE2V2-UBE2N heterodimers catalyze the synthesis of non-canonical 'Lys-63'-linked polyubiquitin chains. This type of polyubiquitination does not lead to protein degradation by the proteasome. Mediates transcriptional activation of target genes. Plays a role in the control of progress through the cell cycle and differentiation. Plays a role in the error-free DNA repair pathway and contributes to the survival of cells after DNA damage. Acts together with the E3 ligases, HLTF and SHPRH, in the 'Lys-63'-linked poly-ubiquitination of PCNA upon genotoxic stress, which is required for DNA repair. Appears to act together with E3 ligase RNF5 in the 'Lys-63'-linked polyubiquitination of JKAMP thereby regulating JKAMP function by decreasing its association with components of the proteasome and ERAD. Promotes TRIM5 capsid-specific restriction activity and the UBE2V1-UBE2N heterodimer acts in concert with TRIM5 to generate 'Lys-63'-linked polyubiquitin chains which activate the MAP3K7/TAK1 complex which in turn results in the induction and expression of NF-kappa-B and MAPK-responsive inflammatory genes (By similarity).[1] [2] [3] [4] [5] [ZNRF1_HUMAN] E3 ubiquitin-protein ligase that mediates the ubiquitination of AKT1 and GLUL, thereby playing a role in neuron cells differentiation. Plays a role in the establishment and maintenance of neuronal transmission and plasticity. Regulates Schwann cells differentiation by mediating ubiquitination of GLUL. Promotes neurodegeneration by mediating 'Lys-48'-linked polyubiquitination and subsequent degradation of AKT1 in axons: degradation of AKT1 prevents AKT1-mediated phosphorylation of GSK3B, leading to GSK3B activation and phosphorylation of DPYSL2/CRMP2 followed by destabilization of microtubule assembly in axons (Probable).[6] Publication Abstract from PubMedRING (Really Interesting New Gene) domains in ubiquitin RING E3 ligases exclusively engage ubiquitin (Ub)-loaded E2s to facilitate ubiquitination of their substrates. Despite such specificity, all RINGs characterized till date bind unloaded E2s with dissociation constants (Kds) in the micromolar to the sub-millimolar range. Here, we show that the RING domain of E3 ligase ZNRF1, an essential E3 ligase implicated in diverse cellular pathways, binds Ube2N with a Kd of approximately 50 nM. This high-affinity interaction is exclusive for Ube2N as ZNRF1 interacts with Ube2D2 with a Kd of approximately 1 microM, alike few other E3s. The crystal structure of ZNRF1 C-terminal domain in complex with Ube2N coupled with mutational analyses reveals the molecular basis of this unusual affinity. We further demonstrate that the ubiquitination efficiency of ZNRF1 : E2 pairs correlates with their affinity. Intriguingly, as a consequence of its high E2 affinity, an excess of ZNRF1 inhibits Ube2N-mediated ubiquitination at concentrations >/=500 nM instead of showing enhanced ubiquitination. This suggests a novel mode of activity regulation of E3 ligases and emphasizes the importance of E3-E2 balance for the optimum activity. Based on our results, we propose that overexpression-based functional analyses on E3 ligases such as ZNRF1 must be approached with caution as enhanced cellular levels might result in aberrant modification activity. Structural insights into the nanomolar affinity of RING E3 ligase ZNRF1 for Ube2N and its functional implications.,Behera AP, Naskar P, Agarwal S, Banka PA, Poddar A, Datta AB Biochem J. 2018 May 9;475(9):1569-1582. doi: 10.1042/BCJ20170909. PMID:29626159[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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