Jeong Jaehoon, Lee Yongju, Choi Giltsu
Department of Biological Sciences, KAIST, Daejeon, Korea.
Nat Commun. 2025 Apr 26;16(1):3946. doi: 10.1038/s41467-025-59327-8.
Phytochrome A (phyA) and phyB are red and far-red photoreceptors that interact with PHYTOCHROME-INTERACTING FACTORs (PIFs) via active phyA-binding (APA) or active phyB-binding (APB) motifs. While APB interacts with the N-terminal photosensory module of phyB (phyB), it remains unclear whether APA interacts with phyA. We report that both phyA and phyB interact with APA through C-terminal output module of phy (phy), while phyB interacts additionally with APB through phyB. Marchantia Mp-phy also interacts with PIFs via the phy-APA interaction. The phyB-APA interaction promotes PIF3 degradation but not mutual phyB destruction. The full-length phy-APA interaction is light-dependent, whereas the underlying phy-APA interaction is not. We show that the Pr form, not the Pfr, of phy competes with APA for phy binding, explaining how the light-dependent phy-APA interaction arises from the light-independent phy-APA interaction. Together, our results suggest that the phy-APA interaction is an ancient feature conserved in both Arabidopsis phyA, phyB and Marchantia Mp-phy.
光敏色素A（phyA）和光敏色素B是红色和远红光光感受器，它们通过活性phyA结合（APA）或活性phyB结合（APB）基序与光敏色素相互作用因子（PIFs）相互作用。虽然APB与phyB的N端光感受模块相互作用，但尚不清楚APA是否与phyA相互作用。我们报告phyA和phyB都通过phy的C端输出模块与APA相互作用，而phyB还通过phyB与APB相互作用。地钱属植物Mp-phy也通过phy-APA相互作用与PIFs相互作用。phyB-APA相互作用促进PIF3降解，但不促进phyB相互降解。全长phy-APA相互作用是光依赖的，而潜在的phy-APA相互作用则不是。我们表明，phy的红光吸收型（Pr）而非远红光吸收型（Pfr）与APA竞争phy结合，这解释了光依赖的phy-APA相互作用如何从光不依赖的phy-APA相互作用中产生。总之，我们的结果表明，phy-APA相互作用是拟南芥phyA、phyB和地钱属植物Mp-phy中保守的古老特征。
