Proteomic analysis of growth signaling integration in Arabidopsis

Background

Light and hormone signaling are crucial for regulating plant growth and development, orchestrating responses to both environmental and internal cues. Recent studies have revealed significant crosstalk between these signaling pathways, where components of the brassinosteroid (BR), auxin, gibberellin (GA), and phytochrome pathways converge. Specifically, transcriptional regulators such as BZR1, PIF4, and ARF6 interact directly, forming a complex network that modulates a shared set of downstream gene targets. This interaction forms the basis of the BAP-D module, a conceptual framework for understanding signal integration in plants. Additionally, the COP1/SPA1 protein complex functions as a central repressor in phytochrome signaling and may play a role in the regulatory activities of the BAP-D complex. However, while genetic and physiological studies have advanced our understanding of these signaling hubs, the underlying biochemical mechanisms remain largely unexplored, highlighting a critical knowledge gap. To address this gap, this project select TurboID as the chosen proximity labeling enzyme, validated in various plant model species. TurboID offers subcellular resolution, making it a powerful tool for studying protein complexes, particularly transcription factors within the BAP-D module located in the nucleus. The enzyme facilitates the mapping of protein-protein interactions with both spatial and temporal precision, and it is also capable of detecting weak and transient interactions within living cells. By leveraging TurboID, this research aims to uncover the biochemical mechanisms underlying the intricate signaling networks in plants.

Aim of the project

In this project, we will investigate how signals are integrated by protein complexes to modulate growth outcomes. Our focus will be on the BAP-D and COP1/SPA complexes, examining their composition and post-translational modifications in response to growth cues and stress. Both complexes are regulated by various inputs—brassinosteroids, auxin, light, and gibberellin for BAP-D, and light for COP1/SPA. The primary aim of the project is to map interactions and modifications to identify key components and regulatory mechanisms that influence growth under stress conditions, using TurboID as the main method. We will first generate stable transgenic lines expressing the TurboID enzyme, followed by TurboID experiments under both normal and stress conditions. The resulting interactome data will then be further validated to ensure the accuracy of the findings.