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Analysis of regulation of a transcription factor RSG contcolling endogenous level of Gibberellins

控制内源赤霉素水平的转录因子RSG的调控分析

基本信息

批准号：
17570031
负责人：
ISHIDA Sarami
金额：
$ 2.44万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

项目摘要

RSG (Repression of Shoot Growth) is a bZIP transcriptional factor which determines elongation growth of stem of plants by regulating expressions of a biosynthetic enzyme for a plant hormone, gibberellin(GA). Besides, it was demonstrated that RSG activates expression of another GA biosynthetic enzyme upon GA feedback regulation. In this context, signals from interior developmental cues and exterior environmental milieus are thought to be integrated on RSG and then converted into its transcriptional activity to maintain GA homeostasis in planta for appropriate elongation growth.For comprehensive understanding of elongation growth by GA in molecular terms, the mechanism by which activity of RSG is regulated was studied.1. The elevation of endogenous level of GA induced phosphorylation of S114 of RSG which is essential for biding with 14-3-3, a negative regulator of RSG.2. The complex between RSG and 14-3-3 was excluded from nucleus resulting shot off of transcription of a GA biosynthetic enzyme by RSG.3. S114 of RSG was specifically phosphorylated by a calcium-dependent protein kinase, NtCDPK1.4. The elevation of endogenous level of GA induced phosphorylation of NtCDPK1 and potentiated the affinity between RSG and NtCDPK1, suggesting RSG and NtCDPK1 could interact beyond the transient association between a kinase and a substrate in the reaction of phosphorylation.In this study, GA signal was probed to be transmitted to RSG via NtCDPK1 in the feedback regulation. The phosphorylation of S114 of RSG by NtCDPK1 leads to the formation of complex between RSG and 14-3-3 resulting the exclusion of the complex from nucleus and repression of transcriptional activation of the GA biosynthetic enzyme by RSG.

RSG（Repression of Shoot Growth）是一种bZIP转录因子，它通过调节植物激素赤霉素（GA）的生物合成酶的表达来决定植物茎的伸长生长。此外，还证明了RSG在GA反馈调节后激活另一种GA生物合成酶的表达。因此，RSG被认为整合了来自内部发育信号和外部环境的信号，并将其转化为转录活性，以维持GA在植物体内的稳态，从而实现适当的伸长生长。为了从分子水平上全面理解GA对RSG活性的调控，本研究对RSG活性的调控机制进行了研究。内源性GA水平的升高可诱导RSG的S114磷酸化，而S114磷酸化是RSG与负调节因子14-3-3结合所必需的. RSG和14-3-3之间的复合物被排除在细胞核之外，导致RSG转录的GA生物合成酶被击落。RSG的S114被钙依赖性蛋白激酶NtCDPK1.4特异性磷酸化。内源性GA水平的升高可诱导NtCDPK 1的磷酸化，并增强RSG与NtCDPK 1之间的亲和力，提示RSG与NtCDPK 1在磷酸化反应中可能存在着超越激酶与底物之间的瞬时结合的相互作用。NtCDPK 1磷酸化RSG的S114，导致RSG与14-3-3之间形成复合物，从而将复合物从核中排除，并抑制RSG对GA生物合成酶的转录激活。