Arabidopsis ROOT PHOTOTROPISM2 is a Light-Dependent Dynamic Modulator of Phototropin1.
Arabidopsis ROOT PHOTOTROPISM2 is a Light-Dependent Dynamic Modulator of Phototropin1.
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拟南芥 ROOT PHOTOTROPISM2 是 Phototropin1 的光依赖性动态调制器。
DOI：
10.1105/tpc.19.00926
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
and Tatsuya Sakai
中科院分区：
文献类型：
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作者：
Taro Kimura;Tomoko Tsuchida-Mayama;Hirotatsu Imai;Koji Okajima;Kosuke Ito;and Tatsuya Sakai
拟南芥 (Arabidopsis thaliana) 蓝光光感受器趋光蛋白 1 (phot1) 是一种蓝光激活的 Ser/Thr 蛋白激酶，可介导各种光反应，包括向光性。 phot1 在下胚轴向光性中的功能依赖于 ROOT PHOTOTROPISM2 (RPT2) 蛋白在广泛的蓝光强度范围内的光诱导。然而，目前尚不清楚 RPT2 如何促进 phot1 对高强度蓝光的光感应适应以及强光条件下的向光性反应。我们发现 RPT2 抑制 phot1 的活性，并证明 RPT2 与 PHOT1 光、氧或电压传感 1 (LOV1) 域结合，这是其高光敏性所必需的。我们的生化分析表明，RPT2 抑制 phot1 的自身磷酸化，表明它通过抑制 LOV1 功能来抑制 phot1 的光敏性和/或激酶活性。我们发现，当 phot1 失活时，RPT2 蛋白会通过泛素-蛋白酶体途径降解，并以 phot1 依赖性方式在蓝光下稳定。我们认为RPT2是一种分子变阻器，可以在任何光强度条件下维持phot1的适度激活水平。
The Arabidopsis (Arabidopsis thaliana) blue light photoreceptor phototropin1 (phot1) is a blue light–activated Ser/Thr protein kinase that mediates various light responses, including phototropism. The function of phot1 in hypocotyl phototropism is dependent on the light induction of ROOT PHOTOTROPISM2 (RPT2) proteins within a broad range of blue light intensities. It is not yet known however how RPT2 contributes to the photosensory adaptation of phot1 to high intensity blue light and the phototropic responses under bright light conditions. We show that RPT2 suppresses the activity of phot1 and demonstrate that RPT2 binds to the PHOT1 light, oxygen or voltage sensing1 (LOV1) domain that is required for its high photosensitivity. Our biochemical analyses revealed that RPT2 inhibits autophosphorylation of phot1, suggesting that it suppresses the photosensitivity and/or kinase activity of phot1 through the inhibition of LOV1 function. We found that RPT2 proteins are degraded via a ubiquitin-proteasome pathway when phot1 is inactive and are stabilized under blue light in a phot1-dependent manner. We propose that RPT2 is a molecular rheostat that maintains a moderate activation level of phot1 under any light intensity conditions.