Dimers of the N-terminal domain of phytochrome B are functional in the nucleus
Dimers of the N-terminal domain of phytochrome B are functional in the nucleus
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DOI：
10.1038/nature01837
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发表时间：
2003-07-31
期刊：
影响因子：
64.8
通讯作者：
Nagatani, A
中科院分区：
文献类型：
--
作者：
Matsushita, T;Mochizuki, N;Nagatani, A
植物通过一些信息感受器，如光敏色素，来调节其对光的反应的发育过程。光敏色素是一种二聚体显色蛋白，调节植物从种子萌发到开花的各个方面(1)。当吸收红光时，光敏色素从细胞质转移到细胞核(2-4)，并通过与PIF3等转录因子的相互作用来调节基因的表达(参考文献5-7)。光敏色素多肽有两个结构域(1，8)：带有发色团的氨基末端光敏结构域和含有信号基序的羧基末端结构域，如激活域(9)。后者被广泛认为是将信号传递到下游组件(1,5810)。在此，我们发现拟南芥光敏色素B的C-末端结构域并不直接参与信号转导，它是光敏色素家族中最重要的成员(1)。从PhyB中分离出的N-末端结构域，当二聚化并定位在细胞核中时，触发了完整的PhyB反应，其光敏性比全长PhyB高得多。这些发现表明，C-末端结构域减弱了PhyB的活性，而不是正向转导信号。
A plant modulates its developmental processes in response to light by several informational photoreceptors such as phytochrome. Phytochrome is a dimeric chromoprotein which regulates various aspects of plant development from seed germination to flowering(1). Upon absorption of red light, phytochrome translocates from the cytoplasm to the nucleus(2-4), and regulates gene expression through interaction with transcription factors such as PIF3 (refs 5-7). The phytochrome polypeptide has two domains(1,8) : the amino-terminal photosensory domain with a chromophore and the carboxy-terminal domain which contains signalling motifs such as a kinase domain(9). The latter is widely believed to transduce the signal to downstream components(1,5,810). Here we show that the C-terminal domain of Arabidopsis phytochrome B (phyB), which is known as the most important member of the phytochrome family(1), is not directly involved in signal transduction. The N-terminal domain isolated from phyB, when dimerized and localized in the nucleus, triggered full phyB responses with much higher photosensitivity than the full-length phyB. These findings indicate that the C-terminal domain attenuates the activity of phyB rather than positively transducing the signal.