State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Agriculture, Nanjing Agricultural University, 210095 Nanjing, China.
Peking University-Southern University of Science and Technology Joint Institute of Plant and Food Sciences, Department of Biology, Southern University of Science and Technology, 518055 Shenzhen, China.
Proc Natl Acad Sci U S A. 2019 Dec 17;116(51):26049-26056. doi: 10.1073/pnas.1915149116. Epub 2019 Nov 27.
Phytochrome B (phyB) absorbs red light signals and subsequently initiates a set of molecular events in plant cells to promote photomorphogenesis. Here we show that phyB directly interacts with B-BOX CONTAINING PROTEIN 4 (BBX4), a positive regulator of red light signaling, and positively controls its abundance in red light. BBX4 associates with PHYTOCHROME INTERACTING FACTOR 3 (PIF3) and represses PIF3 transcriptional activation activity and PIF3-controlled gene expression. The degradation of BBX4 in darkness is dependent on CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) and the 26S proteasome system. Collectively, BBX4 acts as a key component of the phyB-PIF3-mediated signaling module and fine tunes the red light action. phyB promotes the accumulation of BBX4, which in turn serves to repress PIF3 action through direct physical interaction to promote photomorphogenic development in red light.
光敏色素 B（phyB）吸收红光信号，随后在植物细胞中启动一系列分子事件，促进光形态建成。在这里，我们表明 phyB 直接与 BBX4 相互作用，BBX4 是红光信号的正调控因子，并在红光中正向控制其丰度。BBX4 与 PHYTOCHROME INTERACTING FACTOR 3（PIF3）结合，并抑制 PIF3 的转录激活活性和 PIF3 控制的基因表达。在黑暗中，BBX4 的降解依赖于 CONSTITUTIVELY PHOTOMORPHOGENIC 1（COP1）和 26S 蛋白酶体系统。总之，BBX4 作为 phyB-PIF3 介导的信号模块的关键组成部分，通过直接物理相互作用来精细调节红光作用。phyB 促进 BBX4 的积累，BBX4 反过来通过直接物理相互作用抑制 PIF3 的作用，从而促进红光下的光形态建成发育。
