Regulation of phytochrome B nuclear localization through light-dependent unmasking of nuclear-localization signals
Regulation of phytochrome B nuclear localization through light-dependent unmasking of nuclear-localization signals
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DOI：
10.1016/j.cub.2005.02.028
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发表时间：
2005-04-12
期刊：
影响因子：
9.2
通讯作者：
Chory, J
中科院分区：
文献类型：
--
作者：
Chen, M;Tao, Y;Chory, J
光敏色素是一种红色和远红色的光感受器，根据环境光信号调节植物的生长和发育。光敏色素存在于两种光相互转换构象状态：非活性Pr形式和活性Pfr形式。光敏色素亚细胞位置的改变是其生物活性的主要调控机制[1-3]。Pr形式的光敏色素定位于细胞质中，而Pfr形式的光敏色素积聚在细胞核中，与转录因子相互作用以调节基因表达[1,4]。光调控光敏色素易位的分子细节尚不清楚。以拟南芥phyB为模型，我们证明了C端pas相关结构域（PRD）是phyB核导入的必要条件和充分条件，并且整个C端是核体（NB）定位所必需的。我们还发现phyB的n端bilin裂解酶结构域（BILD）和PHY结构域以光依赖的方式直接与PRD相互作用。体内定位研究表明，BLD-PHY足以调节phyB的核积累。对于phyB的核定位，我们的研究结果表明，PRD中的核定位信号被与phyB的发色团附着结构域的相互作用所掩盖，并被光依赖性构象变化所掩盖。
Phytochromes are red and far-red photoreceptors that regulate plant growth and development in response to environmental light cues. Phytochromes exist in two photo-interconvertible conformational states: an inactive Pr form and an active Pfr form. The alteration of phytochromes' subcellular location functions as a major regulatory mechanism of their biological activities [1-3]. Whereas phytochromes in the Pr form localize in the cytoplasm, phytochromes in the Pfr form accumulate in the nucleus, where they interact with transcription factors to regulate gene expression [1, 4]. The molecular details of the regulation of phytochrome translocation by light are poorly understood. Using Arabidopsis phyB as a model, we demonstrate that the C-terminal PAS-related domain (PRD) is both necessary and sufficient for phyB nuclear import and that the entire C terminus is required for nuclear-body (NB) localization. We also show that phyB's N-terminal bilin lyase domain (BILD) and PHY domain interact directly with the PRD in a light-dependent manner. In vivo localization studies indicate that BLD-PHY is sufficient to regulate phyB's nuclear accumulation. For phyB nuclear localization, our results suggest a molecular mechanism in which the nuclear-localization signal in the PRD is masked by interactions with phyB's chromophore-attachment domains and unmasked by light-dependent conformational changes.