Molecular Recognition Research Center, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Republic of Korea; Biomedical Research Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Republic of Korea.
Biomedical Research Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Republic of Korea.
J Mol Biol. 2019 Sep 6;431(19):3900-3912. doi: 10.1016/j.jmb.2019.07.023. Epub 2019 Jul 19.
Deubiquitinating enzymes have key roles in diverse cellular processes whose enzymatic activities are regulated by different mechanisms including post-translational modification. 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 toward the substrate PRP31. Treatment of cells with purvalanol A, a cyclin-dependent kinase inhibitor, results in nuclear translocation of USP15. USP4, another deubiquitinating enzyme 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.
去泛素化酶在多种细胞过程中发挥关键作用，其酶活性受到不同机制的调节，包括翻译后修饰。在这里，我们表明 USP15 被磷酸化，其定位和活性依赖于磷酸化状态。核质分离和质谱分析表明，人 USP15 的 Thr149 和 Thr219 在细胞质中被磷酸化，该区域在不同物种中是保守的。USP15 在这两个位置的磷酸化状态改变了与其伴侣蛋白 SART3 的相互作用，从而导致其核定位和对底物 PRP31 的去泛素化活性。用细胞周期蛋白依赖性激酶抑制剂 purvalanol A 处理细胞，导致 USP15 向核内易位。另一种去泛素化酶 USP4 与 USP15 具有高度的序列同源性和结构域，其活性和定位也表现出 purvalanol A 依赖性变化。总之，我们的数据表明，USP15 和 USP4 的磷酸化修饰对其在剪接体中细胞功能所需的定位的调节很重要。
