Autoinhibition Mechanism of the Ubiquitin-Conjugating Enzyme UBE2S by Autoubiquitination
Autoinhibition Mechanism of the Ubiquitin-Conjugating Enzyme UBE2S by Autoubiquitination
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DOI：
10.1016/j.str.2019.05.008
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发表时间：
2019-08-06
期刊：
影响因子：
5.7
通讯作者：
Lorenz, Sonja
中科院分区：
文献类型：
--
作者：
Liess, Anna K. L.;Kucerova, Alena;Lorenz, Sonja
泛素结合酶(E2s)控制着泛素信号的关键方面。新出现的证据表明，E2的活动受到翻译后修饰的调节；然而，其结构基础在很大程度上尚不清楚。在这里，我们以人类后期促进复合体/环体相关的UBE2S为模型系统，揭示了E2S催化中心附近保守的自动素化事件的结构基础和机制后果。我们结合MD模拟测定的催化泛素载体蛋白结构域的晶体结构表明，活性部位区域是可塑性的，这允许相邻的泛素受体位点Lys(+5)在分子内泛素化。我们通过核磁共振证明，Lys(+5)连接的泛素通过阻止UBE2S与泛素的重新加载来抑制UBE2S。通过免疫沉淀、定量质谱学和siRNA和挽救实验，我们发现UBE2S的Lys(+5)泛素化在有丝分裂退出过程中减少，但不影响该E2的蛋白酶体周转。这些发现表明，UBE2S活性在细胞周期中是内在调节的基础。
Ubiquitin-conjugating enzymes (E2s) govern key aspects of ubiquitin signaling. Emerging evidence suggests that the activities of E2s are modulated by posttranslational modifications; the structural underpinnings, however, are largely unclear. Here, we unravel the structural basis andmechanistic consequences of a conserved autoubiquitination event near the catalytic center of E2s, using the human anaphase-promoting complex/cyclosome-associated UBE2S as a model system. Crystal structures we determined of the catalytic ubiquitin carrier protein domain combined with MD simulations reveal that the active-site region is malleable, which permits an adjacent ubiquitin acceptor site, Lys(+5), to be ubiquitinated intramolecularly. We demonstrate by NMR that the Lys(+5)-linked ubiquitin inhibits UBE2S by obstructing its reloading with ubiquitin. By immunoprecipitation, quantitative mass spectrometry, and siRNA-and-rescue experiments we show that Lys(+5) ubiquitination of UBE2S decreases during mitotic exit but does not influence proteasomal turnover of this E2. These findings suggest that UBE2S activity underlies inherent regulation during the cell cycle.