5l8h
From Proteopedia
Structure of USP46-UbVME
Structural highlights
Function[UBP46_HUMAN] Deubiquitinating enzyme that plays a role in behavior, possibly by regulating GABA action. May act by mediating the deubiquitination of GAD1/GAD67. Has almost no deubiquitinating activity by itself and requires the interaction with WDR48 to have a high activity. Not involved in deubiquitination of monoubiquitinated FANCD2.[1] [UBB_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.[2] [3] Publication Abstract from PubMedRegulation of deubiquitinating enzyme (DUB) activity is an essential step for proper function of cellular ubiquitin signals. UAF1 is a WD40 repeat protein, which binds and activates three important DUBs, USP1, USP12 and USP46. Here, we report the crystal structure of the USP12-Ub/UAF1 complex at a resolution of 2.8A and of UAF1 at 2.3A. In the complex we find two potential sites for UAF1 binding, analogous to what was seen in a USP46/UAF1 complex. In line with these observed dual binding states, we show here that USP12/UAF1 complex has 1:2 stoichiometry in solution, with a two-step binding at 4nM and 325nM respectively. Mutagenesis studies show that the fingers sub-domain of USP12 interacts with UAF1 to form the high affinity interface. Our activation studies confirm that the high affinity binding is important for activation while the second UAF1 binding does not affect activation. Nevertheless, we show that this two step binding is conserved in the well-studied USP12 paralog, USP1. Our results highlight the interfaces essential for regulation of USP12 activity and show a conserved second binding of UAF1 which could be important for regulatory functions independent of USP12 activity. A conserved two-step binding for the UAF1 regulator to the USP12 deubiquitinating enzyme.,Dharadhar S, Clerici M, van Dijk WJ, Fish A, Sixma TK J Struct Biol. 2016 Sep 17. pii: S1047-8477(16)30200-3. doi:, 10.1016/j.jsb.2016.09.011. PMID:27650958[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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