A single chromoprotein with triple chromophores acts as both a phytochrome and a phototropin
A single chromoprotein with triple chromophores acts as both a phytochrome and a phototropin
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DOI：
10.1073/pnas.0603569103
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发表时间：
2006-11
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影响因子：
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通讯作者：
T. Kanegae;Emi Hayashida;Chihiro Kuramoto;M. Wada
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文献类型：
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作者：
T. Kanegae;Emi Hayashida;Chihiro Kuramoto;M. Wada
植物通过三种感光器感知它们的环境光条件，这三种感光器分别在UV、蓝色/近UV和红色/远红光谱范围内吸收。这些光感受器具有与其吸收光谱相对应的特定发色团成分。光敏色素是一种红光/远红光感受器，其发色团为光敏色动素，而蓝/近紫外光感受器隐色素和光敏素则含有一对黄素衍生物。植物使用这些不同的光感受器来评估周围的光环境。光敏色素3(PHY3)是一些蕨类植物中发现的一种红光受体，在弱光下优先生长。PHY3由N-末端的光敏色素发色团结合区和C-末端的几乎全长的趋光素组成。这种不寻常的区域结构意味着，两个不同的光敏系统在这个单一的光感受器中共存，尽管这些光敏系统通常驻留在独立的光感受器中。在这里，我们展示了PHY3作为一个双通道感光器，既具有光敏色素的红光传感系统，又具有光敏素的蓝光传感系统。此外，PHY3感知的红光和蓝光信号在这个单一的染色蛋白中协同处理。这些不同寻常的特性可能会增强PHY3的光敏感度，使蕨类植物能够在弱光的树冠下生长。
Plants sense their environmental light conditions by using three photoreceptors that absorb in the UV, blue/near UV, and red/far-red spectral ranges. These photoreceptors have specific chromophore components corresponding to their absorption spectra. Phytochrome, a red/far-red light receptor, has phytochromobilin as its chromophore, whereas the blue/near UV photoreceptors cryptochrome and phototropin have a pair of flavin derivatives. Plants use these various photoreceptors to assess the surrounding light environment. Phytochrome 3 (PHY3) is a red light receptor found in some ferns, which preferentially grow under weak light. PHY3 is composed of a phytochrome chromophore-binding domain in its N-terminal portion and an almost full-length phototropin in its C-terminal half. This unusual domain organization implies that two different light-sensing systems coexist in this single photoreceptor, although these light-sensing systems usually reside in independent photoreceptors. Here, we show that PHY3 acts as a dual-channel photoreceptor that possesses both the red light-sensing system of phytochrome and the blue light-sensing system of phototropin. Furthermore, red- and blue-light signals perceived by PHY3 are processed synergistically within this single chromoprotein. These unusual properties might confer an enhanced light sensitivity on PHY3, allowing ferns to grow under a low-light canopy.