小柯机器人

北京大学钟上威研究组发现，感觉回路控制细胞膜钙介导的植物色素B光传导。相关论文于2023年3月16日发表于国际学术期刊《细胞》。

研究人员报告了在黑暗到光照过渡期间，控制枯萎幼苗的光感受器phyB核转位的Ca²⁺信号。红光通过phyB刺激细胞膜Ca²⁺急剧增加，这被Ca²⁺结合的蛋白激酶CPK6和CPK12（CPK6/12）感应到。在Ca²⁺激活后，CPK6/12又直接与光活化的phyB在Ser80/Ser106处相互作用并使其磷酸化，启动phyB的核导入。不可磷酸化的突变，即phyB^S80A/S106A，废除了核转位，而且不能回补phyB突变体；而通过将phyB^S80A/S106A与核定位信号相结合，可以完全恢复。研究人员进一步表明，CPK6/12在早期phyB介导的子叶扩展中具有特异性功能，而Ser80/Ser106磷酸化通常支配着phyB的核转位。

这些结果发现了一个以phyB光传导为中心的生化调控回路，并提供了一个范式，将无处不在的Ca²⁺增加与感觉刺激处理中的特定反应联系起来。

研究人员表示，尽管Ca²⁺早已被认为是视觉转导中的一个必要的中间物，但它在植物光转导中的作用仍然难以捉摸。

附：英文原文

Title: Sensory circuitry controls cytosolic calcium-mediated phytochrome B phototransduction

Author: Yan Zhao, Hui Shi, Ying Pan, Mohan Lyu, Zhixuan Yang, Xiaoxia Kou, Xing Wang Deng, Shangwei Zhong

Issue&Volume: 2023/03/16

Abstract: Although Ca2+ has long been recognized as an obligatory intermediate in visual transduction, itsrole in plant phototransduction remains elusive. Here, we report a Ca2+ signaling that controls photoreceptor phyB nuclear translocation in etiolated seedlingsduring dark-to-light transition. Red light stimulates acute cytosolic Ca2+ increases via phyB, which are sensed by Ca2+-binding protein kinases, CPK6 and CPK12 (CPK6/12). Upon Ca2+ activation, CPK6/12 in turn directly interact with and phosphorylate photo-activatedphyB at Ser80/Ser106 to initiate phyB nuclear import. Non-phosphorylatable mutation,phyBS80A/S106A, abolishes nuclear translocation and fails to complement phyB mutant, which is fully restored by combining phyBS80A/S106A with a nuclear localization signal. We further show that CPK6/12 function specificallyin the early phyB-mediated cotyledon expansion, while Ser80/Ser106 phosphorylationgenerally governs phyB nuclear translocation. Our results uncover a biochemical regulatoryloop centered in phyB phototransduction and provide a paradigm for linking ubiquitousCa2+ increases to specific responses in sensory stimulus processing.

DOI: 10.1016/j.cell.2023.02.011

Source: https://www.cell.com/cell/fulltext/S0092-8674(23)00128-9