CRY1 inhibits COP1-mediated degradation of BIT1, a MYB transcription factor, to activate blue light-dependent gene expression in Arabidopsis
CRY1 inhibits COP1-mediated degradation of BIT1, a MYB transcription factor, to activate blue light-dependent gene expression in Arabidopsis
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DOI：
10.1111/j.1365-313x.2008.03508.x
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发表时间：
2008-08-01
期刊：
影响因子：
7.2
通讯作者：
Nam, Hong Gil
中科院分区：
文献类型：
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作者：
Hong, Sung Hyun;Kim, Hyo Jung;Nam, Hong Gil
隐花色素（Cryptochromes，CRY）是在UV-A至蓝光区域中感知光刺激的两大类光感受器之一，并且它们参与植物生长和发育的多个方面。然而，关于其信号转导成分和机制的知识仍然有限。在这里，我们报告了MYB转录因子蓝色不敏感性状1（BIT 1），在控制蓝光反应中起着重要作用。下胚轴的生长反应表明，BIT 1作为一个积极的元素在蓝光信号，因为BIT 1反义和敲除线显示出减少的光响应蓝光。BIT 1控制蓝光依赖的各种基因的表达，如PsbS，捕光复合体基因家族的成员。反式激活试验表明，BIT 1调节启动子活性的PsbS在蓝光依赖性的方式，它需要的PsbS启动子的激活BIT 1。BIT 1在黑暗中降解，而BIT 1以蓝光依赖的方式起稳定BIT 1的作用。相反，COP 1与BIT 1结合并介导其降解。我们认为PsbS启动子在蓝光下通过BIT 1的蓝光依赖性稳定作用被激活，而在黑暗中BIT 1通过COP 1介导的蛋白水解被降解。
Cryptochromes (CRY) are one of the two major classes of photoreceptors that perceive light stimuli in the UV-A to blue light region and they are involved in multiple aspects of plant growth and development. However, knowledge regarding their signaling transduction components and mechanisms remains limited. Here, we report that a MYB transcription factor Blue Insensitive Trait 1 (BIT1), plays an important role in controlling blue light responses. Hypocotyl growth responses indicate that BIT1 functions as a positive element in blue light signaling, since BIT1 antisense and knock-out lines show a reduced light response in blue light. BIT1 controls blue light-dependent expression of various genes such as PsbS, a member of the light-harvesting complex gene family. A transactivation assay showed that BIT1 regulates promoter activity of PsbS in a blue light-dependent manner and that it requires CRY1 for activation of the PsbS promoter. BIT1 undergoes degradation in darkness and CRY1 functions to stabilize BIT1 in a blue light-dependent manner. In contrast, COP1 binds to BIT1 and mediates its degradation. We propose that the PsbS promoter is activated in blue light via the blue light-dependent stabilization of BIT1 by CRY1, while in darkness BIT1 is degraded by COP1-mediated proteolysis.