Huang Aobo, Zhang Jinming, Liu Zhendong, Schoen Vanessa, Verma Deepanjali, Zheng Haiyan, Pedmale Ullas V, Dong Juan
The Waksman Institute of Microbiology, Rutgers, The State University of New Jersey, Piscataway, NJ 08854.
Department of Biochemistry and Biophysics, College of Life and Agricultural Sciences, Texas A&M University, College Station, TX 77843.
Proc Natl Acad Sci U S A. 2025 Aug 12;122(32):e2502445122. doi: 10.1073/pnas.2502445122. Epub 2025 Aug 6.
The formation of a body axis is one of the fundamental steps in developmental patterning in multicellular organisms. Ectopic expression of the stomatal protein BASL (BREAKING OF ASYMMETRY IN THE STOMATAL LINEAGE) reveals a proximal-distal cell polarity field in the leaf and an apical-basal field in the hypocotyl and root of . This provides a framework for uncovering molecular components of body-axis cell polarity in higher plants. In this study, we developed a proximity labeling-based complementation system, termed tSYID (andem fusion of plit-FP and Turbo), to enable simultaneous visualization and identification of the tissue-wide cell polarity module marked by interacting BASL and BREVIS RADIX-LIKE 2 (BRXL2) proteins in . This contact-based tSYID system focuses on identifying the protein interactome proximal to the protein-protein interaction site. By combining proximity labeling and mass spectrometry, we identified protein candidates associated with the tSYID-BASL/BRXL2 module, many of which remain uncharacterized in plants. Among them, an AGC protein kinase displayed highly polarized localization at the basal membrane in the hypocotyl and root. Knocking out two close homologs in resulted in compromised hypocotyl growth in the dark, suggesting a functional connection between basal cell polarity and plant upward growth. Our study demonstrates the power of using the Split-TurboID strategy to uncover proximal proteomes near protein activity sites and highlights an underappreciated crosstalk between developmentally programmed body axes and environmentally influenced growth vectors.
体轴的形成是多细胞生物体发育模式中的基本步骤之一。气孔蛋白BASL（气孔谱系不对称性的打破）的异位表达揭示了叶片中的近端-远端细胞极性场以及下胚轴和根中的顶端-基部场。这为揭示高等植物体轴细胞极性的分子成分提供了一个框架。在本研究中，我们开发了一种基于邻近标记的互补系统，称为tSYID（plit-FP和Turbo的串联融合），以同时可视化和鉴定由相互作用的BASL和BREVIS RADIX-LIKE 2（BRXL2）蛋白标记的全组织细胞极性模块。这种基于接触的tSYID系统专注于识别蛋白质-蛋白质相互作用位点附近的蛋白质相互作用组。通过结合邻近标记和质谱分析，我们鉴定了与tSYID-BASL/BRXL2模块相关的蛋白质候选物，其中许多在植物中仍未被表征。其中，一种AGC蛋白激酶在拟南芥下胚轴和根的基底膜上表现出高度极化的定位。敲除拟南芥中的两个紧密同源物导致黑暗条件下下胚轴生长受损，这表明基底细胞极性与植物向上生长之间存在功能联系。我们的研究证明了使用Split-TurboID策略揭示蛋白质活性位点附近近端蛋白质组的能力，并突出了发育编程的体轴与环境影响的生长向量之间未被充分认识的相互作用。
