PDF(Pubmed)
Abstract：
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 Arabidopsis thaliana deubiquitinating enzyme, Ub-SPECIFIC PROTEASE 14 (UBP14) physically interacts with HY5 and enhances its protein stability by deubiquitination. The da3-1 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 A. thaliana.
摘要：
转录因子ELONGATedHY5（HY5）是幼苗光形态发生的中心中心。E3泛素(Ub)连接酶成分光形态发生1(COP1)通过泛素化抑制HY5蛋白积累。然而,HY5去泛素化的过程，它拮抗E3连接酶介导的泛素化以维持HY5稳态从未被研究过。这里,我们鉴定了拟南芥去泛素化酶，Ub特异性蛋白酶14(UBP14)与HY5物理相互作用并通过去泛素化增强其蛋白质稳定性。缺乏UBP14功能的da3-1突变体表现出长的下胚轴表型，UBP14缺乏导致HY5在黑暗至光照期间无法快速积累。此外,UBP14优选稳定HY5的非磷酸化形式,其更容易与下游靶基因结合。HY5促进UBP14的表达和蛋白质积累，以促进光形态发生。因此，我们的发现建立了UBP14通过去泛素化来稳定HY5蛋白以促进拟南芥中的光形态发生的机制。
