PP7 is a positive regulator of blue light signaling in Arabidopsis
PP7 is a positive regulator of blue light signaling in Arabidopsis
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DOI：
10.1105/tpc.008649
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发表时间：
2003-05-01
期刊：
影响因子：
11.6
通讯作者：
Chua, NH
中科院分区：
文献类型：
--
作者：
Moller, SG;Kim, YS;Chua, NH
隐花色素蓝光光感受器介导植物的各种光形态发生反应，包括下胚轴伸长、子叶扩展和开花时间的控制。拟南芥隐花色素功能的分子机制正变得越来越清楚，最近的研究表明，EST 1和EST 2都位于细胞核中，EST 2受蓝光依赖的磷酸化调节。尽管有这些进展，迄今为止还没有发现阳性隐花色素信号传导成分。在这里，我们证明了一种新的丝氨酸/苏氨酸蛋白磷酸酶（AtPP 7）与果蝇视网膜变性C蛋白磷酸酶具有高度的序列相似性，作为蓝光信号的中间体。AtPP 7表达水平降低的转基因拟南芥幼苗表现出下胚轴生长抑制的损失，并显示有限的子叶扩展响应蓝光照射。这些影响与hy 4突变体幼苗中观察到的那些一样引人注目，hy 4突变体幼苗是在hk 1中缺乏的。我们进一步证明，AtPP 7转录水平是不限速的，AtPP 7可能作用于细胞核中隐花色素的下游，确保通过该途径的信号通量。基于我们的研究结果和最近的数据隐花色素行动，我们建议，AtPP 7作为一个积极的调节隐花色素信号在拟南芥。
The cryptochrome blue light photoreceptors mediate various photomorphogenic responses in plants, including hypocotyl elongation, cotyledon expansion, and control of flowering time. The molecular mechanism of cryptochrome function in Arabidopsis is becoming increasingly clear, with recent studies showing that both CRY1 and CRY2 are localized in the nucleus and that CRY2 is regulated by blue light-dependent phosphorylation. Despite these advances, no positive cryptochrome signaling component has been identified to date. Here, we demonstrate that a novel Ser/Thr protein phosphatase (AtPP7) with high sequence similarity to the Drosophila retinal degeneration C protein phosphatase acts as an intermediate in blue light signaling. Transgenic Arabidopsis seedlings with reduced AtPP7 expression levels exhibit loss of hypocotyl growth inhibition and display limited cotyledon expansion in response to blue light irradiation. These effects are as striking as those seen in hy4 mutant seedlings, which are deficient in CRY1. We further demonstrate that AtPP7 transcript levels are not rate limiting and that AtPP7 probably acts downstream of cryptochrome in the nucleus, ensuring signal flux through the pathway. Based on our findings and recent data regarding cryptochrome action, we propose that AtPP7 acts as a positive regulator of cryptochrome signaling in Arabidopsis.