Phosphorylation of USP15 and USP4 Regulates Localization and Spliceosomal Deubiquitination

Publication date: Available online 19 July 2019Source: Journal of Molecular BiologyAuthor(s): Tanuza Das, Eunice EunKyeong Kim, Eun Joo SongAbstractDeubiquitinating enzymes (DUBs) have key roles in diverse cellular processes whose enzymatic activities are regulated by different mechanisms including post-translational modification (PTM). Here, we show that USP15 is phosphorylated, and its localization and activity are dependent on the phosphorylation status. Nuclear-cytoplasmic fractionation and mass spectrometric analysis revealed that Thr149 and Thr219 of human USP15, which is conserved among different species, are phosphorylated in the cytoplasm. The phosphorylation status of USP15 at these two positions alters the interaction with its partner protein SART3, consequently leading to its nuclear localization and deubiquitinating activity towards the substrate PRP31. Treatment of cells with purvalanol A, a cyclin-dependent kinase (CDK) inhibitor, results in nuclear translocation of USP15. USP4, another deubiquitinating enzyme (DUB) with a high sequence homology and domain structure as USP15, also showed purvalanol A-dependent changes in activity and localization. Collectively, our data suggest that modifications of USP15 and USP4 by phosphorylation are important for the regulation of their localization required for cellular function in the spliceosome.Graphical abstract
Source: Journal of Molecular Biology - Category: Molecular Biology Source Type: research