北京大学王继纵等研究人员合作发现，光诱导的光敏色素B重塑使光敏色素相互作用因子能够进行信号转导。2024年9月23日，国际知名学术期刊《细胞》在线发表了这一成果。
研究人员报告了光激活的光敏色素B（phyB）或组成型活性phyBY276H突变体与光敏色素相互作用因子6（PIF6）复合的冷冻电子显微镜（cryo-EM）结构，揭示了一个相似的三聚体。
色素的光诱导构型转换驱动了phyB中特异性（PHY）结构域附近舌形标志的构象转变。生成的α螺旋PHY舌进一步破坏了暗适应状态下phyB的头尾二聚体。这些phyB的结构重塑促进了PIF6的诱导适配识别，从而稳定了激活的phyB的N端延伸结构域和头对头二聚体。
有趣的是，phyB二聚体表现出轻微的非对称性，导致仅结合一个PIF6分子。总体而言，这些研究结果解决了光诱导的phyB重塑如何促进PIF信号传导这一关键问题，为光敏色素研究提供了新的见解。
据介绍，phyB和光敏色素相互作用因子（PIF）构成了一个公认的信号模块，对于植物适应环境光至关重要。然而，phyB光激活及PIF结合以进行信号转导的机制仍然不清楚。
附：英文原文
Title: Light-induced remodeling of phytochrome B enables signal transduction by phytochrome-interacting factor
Author: Zhengdong Wang, Wenfeng Wang, Didi Zhao, Yanping Song, Xiaoli Lin, Meng Shen, Cheng Chi, Bin Xu, Jun Zhao, Xing Wang Deng, Jizong Wang
Issue&Volume: 2024-09-23
Abstract: Phytochrome B (phyB) and phytochrome-interacting factors (PIFs) constitute a well-established signaling module critical for plants adapting to ambient light. However, mechanisms underlying phyB photoactivation and PIF binding for signal transduction remain elusive. Here, we report the cryo-electron microscopy (cryo-EM) structures of the photoactivated phyB or the constitutively active phyBY276H mutant in complex with PIF6, revealing a similar trimer. The light-induced configuration switch of the chromophore drives a conformational transition of the nearby tongue signature within the phytochrome-specific (PHY) domain of phyB. The resulting α-helical PHY tongue further disrupts the head-to-tail dimer of phyB in the dark-adapted state. These structural remodelings of phyB facilitate the induced-fit recognition of PIF6, consequently stabilizing the N-terminal extension domain and a head-to-head dimer of activated phyB. Interestingly, the phyB dimer exhibits slight asymmetry, resulting in the binding of only one PIF6 molecule. Overall, our findings solve a key question with respect to how light-induced remodeling of phyB enables PIF signaling in phytochrome research.
DOI: 10.1016/j.cell.2024.09.005
Source: https://www.cell.com/cell/abstract/S0092-8674(24)01023-7