Nup96 and HOS1 Are Mutually Stabilized and Gate CONSTANS Protein Level, Conferring Long-Day Photoperiodic Flowering Regulation in Arabidopsis
Nup96 and HOS1 Are Mutually Stabilized and Gate CONSTANS Protein Level, Conferring Long-Day Photoperiodic Flowering Regulation in Arabidopsis
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DOI：
10.1105/tpc.19.00661
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发表时间：
2020-02-01
期刊：
影响因子：
11.6
通讯作者：
Wang, Xu
中科院分区：
文献类型：
--
作者：
Cheng, Zhiyuan;Zhang, Xiaomei;Wang, Xu
核孔蛋白与核膜上的E3连接酶相互作用，维持CONSTANS稳态，从而控制拟南芥长日照开花。核孔复合体深刻地影响开花的时间，然而，其潜在的机制知之甚少。在这里，我们报告说，核孔蛋白96（Nup 96）作为一个负调节长日照光周期开花在拟南芥（拟南芥）。通过多种方法，我们鉴定了E3泛素连接酶渗透反应基因1（HOS 1）的高表达，并证明了其与Nup 96的体内相互作用。Nup 96和HOS 1主要定位于核膜上并相互作用。Nup 96功能的丧失导致HOS 1蛋白的破坏而不改变其mRNA丰度，这导致长日照光周期开花的关键激活剂CONSTANS（CO）蛋白的过度积累，如先前在HOS 1突变体中所报道的。出乎意料的是，HOS 1突变显著降低了Nup 96蛋白水平，表明Nup 96和HOS 1相互稳定，从而形成一种新的抑制性模块，调节CO蛋白的周转。因此，nup 96和hos 1单突变体和nup 96 hos 1双突变体具有高度相似的早花表型和重叠的转录组变化。总之，这项研究揭示了一种抑制机制，其中Nup 96-HOS 1抑制模块控制CO蛋白的水平，从而防止长日照条件下的早熟开花。
A nucleoporin interacts with an E3 ligase on the nuclear membrane, maintaining CONSTANS homeostasis and thereby controlling long-day photoperiodic flowering in Arabidopsis. The nuclear pore complex profoundly affects the timing of flowering; however, the underlying mechanisms are poorly understood. Here, we report that Nucleoporin96 (Nup96) acts as a negative regulator of long-day photoperiodic flowering in Arabidopsis (Arabidopsis thaliana). Through multiple approaches, we identified the E3 ubiquitin ligase HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENE1 (HOS1) and demonstrated its interaction in vivo with Nup96. Nup96 and HOS1 mainly localize and interact on the nuclear membrane. Loss of function of Nup96 leads to destruction of HOS1 proteins without a change in their mRNA abundance, which results in overaccumulation of the key activator of long-day photoperiodic flowering, CONSTANS (CO) proteins, as previously reported in hos1 mutants. Unexpectedly, mutation of HOS1 strikingly diminishes Nup96 protein level, suggesting that Nup96 and HOS1 are mutually stabilized and thus form a novel repressive module that regulates CO protein turnover. Therefore, the nup96 and hos1 single and nup96 hos1 double mutants have highly similar early-flowering phenotypes and overlapping transcriptome changes. Together, this study reveals a repression mechanism in which the Nup96-HOS1 repressive module gates the level of CO proteins and thereby prevents precocious flowering in long-day conditions.