The phytochrome (phy) family of sensory photoreceptors modulates developmental programs in response to ambient light. Phys also control gene expression in part by directly interacting with the bHLH class of transcription factors, PHYTOCHROME-INTERACTING FACTORS (PIFs), and inducing their rapid phosphorylation and degradation. Several kinases have been shown to phosphorylate PIFs and promote their degradation. However, the phosphatases that dephosphorylate PIFs are less understood. Here, we describe four regulatory subunits of the Arabidopsis (Arabidopsis thaliana) protein PHOSPHATASE 2A (PP2A) family (B'α, B'β, B''α and B''β) that interact with PIF3 in yeast two-hybrid, in vitro and in vivo assays. The pp2ab''αβ and b''αβ/b'αβ mutants displayed short hypocotyls, while the overexpression of the B subunits induced longer hypocotyls compared to the wild type under red light. The light-induced degradation of PIF3 was faster in the b''αβ/b'αβ quadruple mutant compared to in the wild type. Consistently, immunoprecipitated PP2A A and B subunits directly dephosphorylated PIF3-MYC in vitro. RNA-seq analyses showed that B''α and B''β alter global gene expression in response to red light. PIFs (PIF1, PIF3, PIF4 and PIF5) are epistatic to these B subunits in regulating hypocotyl elongation under red light. Collectively, these data show an essential function of PP2A in dephosphorylating PIF3 to modulate photomorphogenesis in Arabidopsis.

中文翻译：

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磷酸酶 2A 使植物色素相互作用FACTOR3去磷酸化，以调节拟南芥的光形态发生


感觉光感受器的植物色素 （phy） 家族根据环境光调节发育程序。Phys 还通过直接与 bHLH 类转录因子 PHYTOCHROME-INTERACTING FACTORS （PIF） 相互作用并诱导其快速磷酸化和降解来部分控制基因表达。几种激酶已被证明可以磷酸化 PIF 并促进其降解。然而，使 PIF 去磷酸化的磷酸酶知之甚少。在这里，我们描述了拟南芥（拟南芥）蛋白磷酸酶 2A （PP2A） 家族（B'α、B'β、B''α 和 B''β）的四个调节亚基，它们在酵母双杂交、体外和体内测定中与 PIF3 相互作用。pp2ab''αβ 和 b''αβ/b'αβ 突变体表现出短的下胚轴，而 B 亚基的过表达在红光下与野生型相比诱导更长的下胚轴。与野生型相比，b''αβ/b'αβ 四重突变体中 PIF3 的光诱导降解更快。一致，免疫沉淀的 PP2A A 和 B 亚基在体外直接使 PIF3-MYC 去磷酸化。RNA-seq 分析表明，B''α 和 B''β响应红光改变整体基因表达。PIFs （PIF1 、 PIF3 、 PIF4 和 PIF5） 在红光下调节下胚轴伸长时与这些 B 亚基上位。总的来说，这些数据表明 PP2A 在去磷酸化 PIF3 以调节拟南芥的光形态发生中具有重要功能。