Arabidopsis Blue Light Receptor Phototropin 1 Undergoes Blue Light-Induced Activation in Membrane Microdomains  

作　　者：Yiqun Xue Jingjing Xing Yinglang Wan Xueqin Lv Lusheng Fan Yongdeng Zhang Kai Song Li Wang Xiaohua Wang Xin Deng Frantisek Baluska John M. Christie Jinxing Lin 

机构地区：[1]Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China [2]University of Chinese Academy of Sciences, Beijing 100049, China [3]Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA [4]Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA [5]Institute of Cellular and Molecular Botany, University of Bonn, 53115 Bonn, Germany [6]Institute of Molecular, Cell and Systems Biology, University of Glasgow, Bower Building, Glasgow G12 8QQ, UK [7]College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China

出　　处：《Molecular Plant》2018年第6期846-859,共14页分子植物（英文版）

基　　金：This work is supported by the National Natural Science Foundation of China （31530084, 31270224） and the Program of Introducing Talents of Discipline to Universities （111 project, B13007）.

摘　　要：Phototropin （phot）-mediated signaling initiated by blue light （BL） plays a critical role in optimizing photosyn- thetic light capture at the plasma membrane （PM） in plants. However, the mechanisms underlying the regu- lation of phot activity at the PM in response to BL remain largely unclear. In this study, by single-particle tracking and stepwise photobleaching analysis of photl-GFP proteins we demonstrated that in the dark photl proteins remain in an inactive state and mostly exist as monomers. Dimerization and the diffusion rate of photl-GFP increased in a dose-dependent manner in response to BL. In contrast, BL did not affect the lateral diffusion of kinase-inactive photlD806N-GFP but did enhance its dimerization, suggesting that photl dimerization is independent of phosphorylation. Forster resonance energy transfer-fluorescence life- time imaging microscopy analysis revealed that the interaction between photl-GFP and a marker of sterol- rich lipid environments, AtRem1.3-mCherry, was enhanced with increased time of BL treatment. However, this BL-dependent interaction was not obvious in plants co-expressing phot1D806N-GFP and AtRem1.3- mCherry, indicating that BL facilitates the translocation of functional photl-GFP into AtRem1.3-1abeled microdomains to activate phot-mediated signaling. Conversely, sterol depletion attenuated photl-GFP dynamics, dimerization, and phosphorylation. Taken together, these results indicate that membrane micro- domains act as organizing platforms essential for the proper function of activated photl at the PM.Phototropin （phot）-mediated signaling initiated by blue light （BL） plays a critical role in optimizing photosyn- thetic light capture at the plasma membrane （PM） in plants. However, the mechanisms underlying the regu- lation of phot activity at the PM in response to BL remain largely unclear. In this study, by single-particle tracking and stepwise photobleaching analysis of photl-GFP proteins we demonstrated that in the dark photl proteins remain in an inactive state and mostly exist as monomers. Dimerization and the diffusion rate of photl-GFP increased in a dose-dependent manner in response to BL. In contrast, BL did not affect the lateral diffusion of kinase-inactive photlD806N-GFP but did enhance its dimerization, suggesting that photl dimerization is independent of phosphorylation. Forster resonance energy transfer-fluorescence life- time imaging microscopy analysis revealed that the interaction between photl-GFP and a marker of sterol- rich lipid environments, AtRem1.3-mCherry, was enhanced with increased time of BL treatment. However, this BL-dependent interaction was not obvious in plants co-expressing phot1D806N-GFP and AtRem1.3- mCherry, indicating that BL facilitates the translocation of functional photl-GFP into AtRem1.3-1abeled microdomains to activate phot-mediated signaling. Conversely, sterol depletion attenuated photl-GFP dynamics, dimerization, and phosphorylation. Taken together, these results indicate that membrane micro- domains act as organizing platforms essential for the proper function of activated photl at the PM.

关 键 词：photl VA-TIRFM spatiotemporal dynamics blue light signaling membrane microdomains 

分 类 号：Q26[生物学—细胞生物学] X173[环境科学与工程—环境科学]