DET1-mediated degradation of a SAGA-like deubiquitination module controls H2Bub homeostasis

DE-ETIOLATED 1 (DET1) is an evolutionarily conserved component of the ubiquitination machinery that mediates the destabilization of key regulators of cell differentiation and proliferation in multicellular organisms. In this study, we provide evidence from Arabidopsis that DET1 is essential for the regulation of histone H2B monoubiquitination (H2Bub) over most genes by controlling the stability of a plant deubiquitination module (DUBm). In contrast with yeast and metazoan DUB modules that are associated with the large SAGA complex, the Arabidopsis DUBm only comprises three proteins (hereafter named SGF11, ENY2 and UBP22) and appears to act independently as a major H2Bub deubiquitinase activity. Our study further unveils that DET1-DDB1-Associated-1 (DDA1) protein interacts with SGF11 in vivo, linking the DET1 complex to light-dependent ubiquitin-mediated proteolytic degradation of the DUBm. Collectively, these findings uncover a signaling path controlling DUBm availability, potentially adjusting H2Bub turnover capacity to the cell transcriptional status. Refer to individual Series

DE-ETIOLATED 1（DET1）是一类进化保守的泛素化系统组分，可介导多细胞生物内细胞分化与增殖关键调控因子的不稳定化。本研究以拟南芥为实验材料，提供证据表明DET1可通过调控植物去泛素化模块（deubiquitination module, DUBm）的稳定性，对多数基因区域的组蛋白H2B单泛素化（histone H2B monoubiquitination, H2Bub）发挥至关重要的调控作用。相较于结合大型SAGA复合物的酵母及后生动物去泛素化模块，拟南芥的DUBm仅包含三种蛋白（下文分别命名为SGF11、ENY2与UBP22），且似乎作为核心的H2Bub去泛素酶活性复合物独立发挥功能。本研究进一步揭示，DET1-DDB1关联蛋白1（DET1-DDB1-Associated-1, DDA1）可在体内与SGF11相互作用，将DET1复合物与光依赖的泛素介导DUBm蛋白降解通路建立关联。综上，这些发现揭示了一条调控DUBm可用性的信号通路，可根据细胞转录状态调整H2Bub的周转能力。详见各独立数据集系列