Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610064, China.
Solid-State Fermentation Resource Utilization Key Laboratory of Sichuan Province, Department of Agriculture Forestry and Food Engineering, Yibin University, Yibin 644000, China.
Proc Natl Acad Sci U S A. 2024 Aug 13;121(33):e2404883121. doi: 10.1073/pnas.2404883121. Epub 2024 Aug 5.
Transcription factor ELONGATED HYPOCOTYL5 (HY5) is the central hub for seedling photomorphogenesis. E3 ubiquitin (Ub) ligase CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) inhibits HY5 protein accumulation through ubiquitination. However, the process of HY5 deubiquitination, which antagonizes E3 ligase-mediated ubiquitination to maintain HY5 homeostasis has never been studied. Here, we identified that deubiquitinating enzyme, Ub-SPECIFIC PROTEASE 14 (UBP14) physically interacts with HY5 and enhances its protein stability by deubiquitination. The mutant lacking UBP14 function exhibited a long hypocotyl phenotype, and UBP14 deficiency led to the failure of rapid accumulation of HY5 during dark to light. In addition, UBP14 preferred to stabilize nonphosphorylated form of HY5 which is more readily bound to downstream target genes. HY5 promoted the expression and protein accumulation of UBP14 for positive feedback to facilitate photomorphogenesis. Our findings thus established a mechanism by which UBP14 stabilizes HY5 protein by deubiquitination to promote photomorphogenesis in .
转录因子 ELONGATED HYPOCOTYL5（HY5）是幼苗光形态建成的中心枢纽。E3 泛素（Ub）连接酶 CONSTITUTIVE PHOTOMORPHOGENIC 1（COP1）通过泛素化抑制 HY5 蛋白积累。然而，HY5 去泛素化的过程，即拮抗 E3 连接酶介导的泛素化以维持 HY5 体内平衡，从未被研究过。在这里，我们鉴定出去泛素化酶 Ub-SPECIFIC PROTEASE 14（UBP14）与 HY5 物理相互作用，并通过去泛素化增强其蛋白稳定性。缺乏 UBP14 功能的 突变体表现出长下胚轴表型，UBP14 缺乏导致 HY5 在黑暗到光照期间快速积累的失败。此外，UBP14 更倾向于稳定非磷酸化形式的 HY5，这种形式更容易与下游靶基因结合。HY5 促进 UBP14 的表达和蛋白积累，形成正反馈，促进光形态建成。我们的研究结果因此建立了一个机制，即 UBP14 通过去泛素化稳定 HY5 蛋白，从而促进 中的光形态建成。
