State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
Int J Mol Sci. 2022 Feb 18;23(4):2273. doi: 10.3390/ijms23042273.
Phosphorus is an essential macronutrient for plants. The phosphate (Pi) concentration in soil solutions is typically low, and plants always suffer from low-Pi stress. During Pi starvation, a number of adaptive mechanisms in plants have evolved to increase Pi uptake, whereas the mechanisms are not very clear. Here, we report that an ubiquitin E3 ligase, PRU2, modulates Pi acquisition in Arabidopsis response to the low-Pi stress. The mutant showed arsenate-resistant phenotypes and reduced Pi content and Pi uptake rate. The complementation with restored these to wild-type plants. PRU2 functioned as an ubiquitin E3 ligase, and the protein accumulation of PRU2 was elevated during Pi starvation. PRU2 interacted with a kinase CK2α1 and a ribosomal protein RPL10 and degraded CK2α1 and RPL10 under low-Pi stress. The in vitro phosphorylation assay showed that CK2α1 phosphorylated PHT1;1 at Ser-514, and prior reports demonstrated that the phosphorylation of PHT1;1 Ser-514 resulted in PHT1;1 retention in the endoplasmic reticulum. Then, the degradation of CK2α1 by PRU2 under low-Pi stress facilitated PHT1;1 to move to the plasma membrane to increase Arabidopsis Pi uptake. Taken together, this study demonstrated that the ubiquitin E3 ligase-PRU2-was an important positive regulator in modulating Pi acquisition in Arabidopsis response to low-Pi stress.
磷是植物必需的大量营养素。土壤溶液中的磷酸盐（Pi）浓度通常较低，植物总是受到低 Pi 胁迫的影响。在 Pi 饥饿时，植物中已经进化出许多适应机制来增加 Pi 的吸收，而这些机制尚不清楚。在这里，我们报告说泛素 E3 连接酶 PRU2 调节拟南芥对低 Pi 胁迫的 Pi 吸收。突变体[ru2]表现出砷酸盐抗性表型和降低的 Pi 含量和 Pi 吸收速率。与[ru2]互补恢复了这些野生型植物的特性。PRU2 作为泛素 E3 连接酶起作用，并且在 Pi 饥饿期间 PRU2 的蛋白积累增加。PRU2 与激酶 CK2α1 和核糖体蛋白 RPL10 相互作用，并在低 Pi 胁迫下降解 CK2α1 和 RPL10。体外磷酸化实验表明 CK2α1 在 Ser-514 处磷酸化 PHT1;1，而先前的报道表明 PHT1;1 Ser-514 的磷酸化导致 PHT1;1 在 ER 中保留。然后，PRU2 在低 Pi 胁迫下降解 CK2α1 有助于 PHT1;1 移动到质膜以增加拟南芥 Pi 吸收。总之，这项研究表明，泛素 E3 连接酶-PRU2-是调节拟南芥对低 Pi 胁迫的 Pi 吸收的重要正调控因子。
