The Protein Phosphatase 4 and SMEK1 Complex Dephosphorylates HYL1 to Promotemi RNA Biogenesis by Antagonizing the MAPK Cascade in Arabidopsis
The Protein Phosphatase 4 and SMEK1 Complex Dephosphorylates HYL1 to Promotemi RNA Biogenesis by Antagonizing the MAPK Cascade in Arabidopsis
复制标题
拟南芥中蛋白磷酸酶 4 和 SMEK1 复合物使 HYL1 去磷酸化，通过拮抗 MAPK 级联促进 mi RNA 生物发生
DOI：
10.1016/j.devcel.2017.05.008
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发表时间：
2017-06-05
影响因子：
11.8
通讯作者：
Zheng, Binglian
中科院分区：
文献类型：
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作者：
Su, Chuanbin;Li, Ziwei;Zheng, Binglian
磷酸化通过调节miRNA生物发生机制的辅助因子，在miRNA加工过程中起着至关重要的作用。HYL1 （Hyponastic Leaves 1）是一种短寿命磷蛋白，是植物miRNA生物发生的核心辅助因子。然而，HYL1的稳定性和磷酸化的精确平衡和调控机制尚不清楚。本研究表明，在拟南芥中，高度保守的PP4（蛋白磷酸酶4）和SMEK1 （MEK1抑制因子）复合物通过拮抗MAPK级联，使HYL1去磷酸化，从而促进miRNA的生物发生。smek1突变体由于HYL1的加速降解而表现出miRNA生物发生缺陷。SMEK1以双重方式稳定HYL1：作为抑制因子，SMEK1抑制MAPK激活以减弱HYL1的磷酸化；SMEK1组装一个功能性的PP4来靶向HYL1去磷酸化。此外，SMEK1的蛋白水平在脱落酸的作用下升高。我们的研究结果为miRNA生物发生过程中蛋白激酶和磷酸酶之间的微妙平衡提供了见解。
Phosphorylation plays an essential role in microRNA (miRNA) processing by regulating co-factors of the miRNA biogenesis machinery. HYL1 (Hyponastic Leaves 1), a core co-factor in plant miRNA biogenesis, is a short-lived phosphoprotein. However, the precise balance and regulatory mechanism of the stability and phosphorylation of HYL1 remain unclear. Here, we show that a highly conserved PP4 (Protein Phosphatase 4) and SMEK1 (Suppressor of MEK 1) complex dephosphorylates HYL1 to promote miRNA biogenesis, by antagonizing the MAPK cascade in Arabidopsis. The smek1 mutants exhibit defective miRNA biogenesis due to accelerated degradation of HYL1. SMEK1 stabilizes HYL1 in a dual manner: SMEK1, as a suppressor, inhibits MAPK activation to attenuate HYL1 phosphorylation; SMEK1 assembles a functional PP4 to target HYL1 for dephosphorylation. Moreover, the protein level of SMEK1 is increased in response to abscisic acid. Our results provide insights into the delicate balance between a protein kinase and a phosphatase during miRNA biogenesis.