Arabidopsis CRY2 and ZTL mediate blue-light regulation of the transcription factor CIB1 by distinct mechanisms
Arabidopsis CRY2 and ZTL mediate blue-light regulation of the transcription factor CIB1 by distinct mechanisms
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DOI：
10.1073/pnas.1308987110
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发表时间：
2013-10-22
影响因子：
11.1
通讯作者：
Lin, Chentao
中科院分区：
文献类型：
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作者：
Liu, Hongtao;Wang, Qin;Lin, Chentao
植物具有多种光感受器来介导生长和发育的光调节，但是还不清楚不同的光感受器如何协调它们的行为以共同调节发育反应，例如开花时间。在拟南芥中，光激发的隐花色素2与转录因子CIB 1相互作用，激活转录和花的起始。我们发现CIB 1蛋白的表达受蓝光的调控; CIB 1在暴露于蓝光的植物中高度表达，但在没有蓝光的情况下CIB 1蛋白的水平降低。我们证明CIB 1被26 S蛋白酶体降解，蓝光抑制CIB 1降解。令人惊讶的是，尽管隐花色素2在响应蓝光时与CIB 1物理相互作用，但它不是介导蓝光抑制CIB 1降解的光感受器。相反，三种光氧电压（LOV）域光感受器中的两种，ZEITLUPE和LOV KELCH蛋白2，而不是黄素结合KELCH重复1，是CIB 1降解的功能和蓝光抑制所必需的。这些结果支持的假设，进化无关的蓝光受体，隐花色素和LOV结构域的F-盒蛋白，介导相同的转录因子的蓝光调节不同的机制。
Plants possess multiple photoreceptors to mediate light regulation of growth and development, but it is not well understood how different photoreceptors coordinate their actions to jointly regulate developmental responses, such as flowering time. In Arabidopsis, the photoexcited cryptochrome 2 interacts with the transcription factor CRYPTOCHROME-INTERACTING basic helix-loop-helix 1 (CIB1) to activate transcription and floral initiation. We show that the CIB1 protein expression is regulated by blue light; CIB1 is highly expressed in plants exposed to blue light, but levels of the CIB1 protein decreases in the absence of blue light. We demonstrate that CIB1 is degraded by the 26S proteasome and that blue light suppresses CIB1 degradation. Surprisingly, although cryptochrome 2 physically interacts with CIB1 in response to blue light, it is not the photoreceptor mediating blue-light suppression of CIB1 degradation. Instead, two of the three light-oxygen-voltage (LOV)-domain photoreceptors, ZEITLUPE and LOV KELCH PROTEIN 2, but not FLAVIN-BINDING KELCH REPEAT 1, are required for the function and blue-light suppression of degradation of CIB1. These results support the hypothesis that the evolutionarily unrelated blue-light receptors, cryptochrome and LOV-domain F-box proteins, mediate blue-light regulation of the same transcription factor by distinct mechanisms.