Dual Activities of Plant cGMP-Dependent Protein Kinase and Its Roles in Gibberellin Signaling and Salt Stress
Dual Activities of Plant cGMP-Dependent Protein Kinase and Its Roles in Gibberellin Signaling and Salt Stress
复制标题
DOI：
10.1105/tpc.19.00510
复制
发表时间：
2019-12-01
期刊：
影响因子：
11.6
通讯作者：
Hong, Yueyun
中科院分区：
文献类型：
--
作者：
Shen, Qingwen;Zhan, Xinqiao;Hong, Yueyun
环磷酸鸟苷（cGMP）是真核生物中重要的调节因子，而cGMP依赖性蛋白激酶（PKG）在动物多种生理过程中对细胞内cGMP的感知起着关键作用。然而，PKG在植物中的分子身份，性质和功能仍然是难以捉摸的。在这项研究中，我们已经确定了PKG从植物和其功能介导的赤霉素（GA）在水稻（水稻）的反应。来自植物的PKG在结构上是独特的，具有额外的2C型蛋白磷酸酶结构域。水稻PKG同时具有蛋白激酶和磷酸酶活性，cGMP可刺激PKG的激酶活性而抑制其磷酸酶活性。PKG的靶点之一是GAMYB，GAMYB是GA信号传导中的转录因子，PKG的双重活性催化GAMYB在Ser（6）处的可逆磷酸化，并调节GAMYB响应GA的核质分布。PKG的丢失阻碍了核定位的GAMYB和废除的GA响应中的GAMYB功能，导致GA诱导的种子萌发，节间伸长和花粉活力的缺陷。除GAMYB外，PKG还具有多个潜在靶点，因此具有广泛的作用，特别是在盐胁迫反应中。
Cyclic GMP (cGMP) is an important regulator in eukaryotes, and cGMP-dependent protein kinase (PKG) plays a key role in perceiving cellular cGMP in diverse physiological processes in animals. However, the molecular identity, property, and function of PKG in plants remain elusive. In this study, we have identified PKG from plants and characterized its role in mediating the gibberellin (GA) response in rice (Oryza sativa). PKGs from plants are structurally unique with an additional type 2C protein phosphatase domain. Rice PKG possesses both protein kinase and phosphatase activities, and cGMP stimulates its kinase activity but inhibits its phosphatase activity. One of PKG's targets is GAMYB, a transcription factor in GA signaling, and the dual activities of PKG catalyze the reversible phosphorylation of GAMYB at Ser(6) and modulate the nucleocytoplasmic distribution of GAMYB in response to GA. Loss of PKG impeded the nuclear localization of GAMYB and abolished GAMYB function in the GA response, leading to defects in GA-induced seed germination, internode elongation, and pollen viability. In addition to GAMYB, PKG has multiple potential targets and thus has broad effects, particularly in the salt stress response.