Centre for Biological Systems Analysis (ZBSA), University of Freiburg, 79104 Freiburg, Germany.
Cell. 2011 Sep 2;146(5):813-25. doi: 10.1016/j.cell.2011.07.023.
Phytochrome A (phyA) is the only photoreceptor in plants, initiating responses in far-red light and, as such, essential for survival in canopy shade. Although the absorption and the ratio of active versus total phyA are maximal in red light, far-red light is the most efficient trigger of phyA-dependent responses. Using a joint experimental-theoretical approach, we unravel the mechanism underlying this shift of the phyA action peak from red to far-red light and show that it relies on specific molecular interactions rather than on intrinsic changes to phyA's spectral properties. According to our model, the dissociation rate of the phyA-FHY1/FHL nuclear import complex is a principle determinant of the phyA action peak. The findings suggest how higher plants acquired the ability to sense far-red light from an ancestral photoreceptor tuned to respond to red light.
光敏色素 A（phyA）是植物中唯一的光受体，在远红光中引发反应，因此对于树冠遮荫下的生存至关重要。尽管在红光中吸收和活性与总 phyA 的比值最大，但远红光却是触发 phyA 依赖反应最有效的光。我们采用联合实验理论的方法，揭示了 phyA 作用峰从红光转移到远红光的机制，并表明这依赖于特定的分子相互作用，而不是 phyA 光谱特性的内在变化。根据我们的模型，phyA-FHY1/FHL 核输入复合物的解离速率是 phyA 作用峰的主要决定因素。这些发现表明高等植物是如何从一个对红光敏感的祖先光受体获得感应远红光的能力的。
