Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, P.R.China.
Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, P.R.China.
Dev Cell. 2021 Feb 8;56(3):310-324.e7. doi: 10.1016/j.devcel.2020.12.001. Epub 2020 Dec 23.
Arabidopsis GLYCOGEN SYNTHASE KINASE 3 (GSK3)-like kinases play various roles in plant development, including chloroplast development, but the underlying molecular mechanism is not well defined. Here, we demonstrate that transcription factors GLK1 and GLK2 interact with and are phosphorylated by the BRASSINOSTEROID insensitive2 (BIN2). The loss-of-function mutant of BIN2 and its homologs, bin2-3 bil1 bil2, displays abnormal chloroplast development, whereas the gain-of-function mutant, bin2-1, exhibits insensitivity to BR-induced de-greening and reduced numbers of thylakoids per granum, suggesting that BIN2 positively regulates chloroplast development. Furthermore, BIN2 phosphorylates GLK1 at T175, T238, T248, and T256, and mutations of these phosphorylation sites alter GLK1 protein stability and DNA binding and impair plant responses to BRs/darkness. On the other hand, BRs and darkness repress the BIN2-GLK module to enhance BR/dark-mediated de-greening and impair the formation of the photosynthetic apparatus. Our results thus provide a mechanism by which BRs modulate photomorphogenesis and chloroplast development.
拟南芥糖基转移酶激酶 3（GSK3）样激酶在植物发育中发挥多种作用，包括叶绿体发育，但潜在的分子机制尚不清楚。在这里，我们证明转录因子 GLK1 和 GLK2 与油菜素内酯不敏感 2（BIN2）相互作用并被其磷酸化。BIN2 及其同源物 bin2-3 bil1 bil2 的功能丧失突变体表现出异常的叶绿体发育，而功能获得性突变体 bin2-1 对 BR 诱导的去绿化和每个粒状体的类囊体数量减少表现出不敏感，表明 BIN2 正向调控叶绿体发育。此外，BIN2 在 T175、T238、T248 和 T256 处磷酸化 GLK1，并且这些磷酸化位点的突变改变 GLK1 蛋白稳定性和 DNA 结合并损害植物对 BRs/黑暗的反应。另一方面，BRs 和黑暗抑制 BIN2-GLK 模块，以增强 BR/黑暗介导的去绿化并损害光合器官的形成。因此，我们的研究结果提供了 BR 调节光形态发生和叶绿体发育的机制。
