7r2g
From Proteopedia
USP15 D1D2 in catalytically-competent state bound to mitoxantrone stack (isoform 2)
Structural highlights
FunctionUBP15_HUMAN Hydrolase that removes conjugated ubiquitin from target proteins and regulates various pathways such as the TGF-beta receptor signaling and NF-kappa-B pathways. Acts as a key regulator of TGF-beta receptor signaling pathway, but the precise mechanism is still unclear: according to a report, acts by promoting deubiquitination of monoubiquitinated R-SMADs (SMAD1, SMAD2 and/or SMAD3), thereby alleviating inhibition of R-SMADs and promoting activation of TGF-beta target genes (PubMed:21947082). According to another reports, regulates the TGF-beta receptor signaling pathway by mediating deubiquitination and stabilization of TGFBR1, leading to an enhanced TGF-beta signal (PubMed:22344298). Able to mediate deubiquitination of monoubiquitinated substrates as well as 'Lys-48'-linked polyubiquitin chains, protecting them against proteasomal degradation. Acts as an associated component of COP9 signalosome complex (CSN) and regulates different pathways via this association: regulates NF-kappa-B by mediating deubiquitination of NFKBIA and deubiquitinates substrates bound to VCP. Protects APC and human papillomavirus type 16 protein E6 against degradation via the ubiquitin proteasome pathway.[1] [2] [3] [4] [5] [6] [7] Publication Abstract from PubMedUbiquitin specific protease USP15 is a deubiquitinating enzyme reported to regulate several biological and cellular processes, including TGF-beta signaling, regulation of immune response, neuro-inflammation and mRNA splicing. Here we study the USP15 D1D2 catalytic domain and present the crystal structure in its catalytically-competent conformation. We compare this apo-structure to a previous misaligned state in the same crystal lattice. In both structures, mitoxantrone, an FDA approved antineoplastic drug and a weak inhibitor of USP15 is bound, indicating that it is not responsible for inducing a switch in the conformation of active site cysteine in the USP15 D1D2 structure. Instead, mitoxantrone contributes to crystal packing, by forming a stack of 12 mitoxantrone molecules. We believe this reflects how mitoxantrone can be responsible for e.g. nuclear condensate partitioning. We conclude that USP15 can switch between active and inactive states in the absence of ubiquitin, and that this is independent of mitoxantrone binding. These insights can be important for future drug discovery targeting USP15. Mitoxantrone stacking does not define the active or inactive state of USP15 catalytic domain.,Priyanka A, Tisi D, Sixma TK J Struct Biol. 2022 May 20;214(3):107862. doi: 10.1016/j.jsb.2022.107862. PMID:35605756[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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