Interactions protéine-protéine et traitement de signaux multiples par les plantes – PPI-Processing

Hormones govern morphogenesis and physiology of plants throughout their life. They do not act in isolation. Rather, different plant hormone combinations integrate environmental signals with the plant genetic program to regulate coordinately plant biology. Many direct protein-protein interactions between effectors of different hormone signaling pathways have been identified, providing a putative mechanism for coupling the activity of two or more hormonal signals. How protein-protein interactions enable and regulate multi-signal processing by hormone signaling pathways has not been analyzed so far, and will constitute the central question addressed in this project. We will focus on auxin, cytokinin and gibberellins, three essential plant hormones. Building on a wealth of published and unpublished work where we have reconstructed fully functional plant hormone signaling pathways in a bottom-up approach in mammalian cells, we will use a synthetic biology approach to explore quantitatively how known protein-protein interactions between effectors of different signaling pathways regulate transcriptional activity in response to multiple hormones. This comprises advanced confocal microscopy technologies and mid-/high-throughput gene-expression quantitative assays. We will also perform an exhaustive analysis of inter-pathway protein-protein interactions and further study the functional significance of a selection of these interactions. We will identify mutations that weaken or enhance protein-protein interactions as well as create novel interaction capacities between signaling effectors to perturb the coupling between signaling pathways. Knowledge generated in our mammalian orthogonal system will then be tested in planta to further understand how multi-hormone processing empowered by protein-protein interactions act to regulate the dynamics of plant development. Our analysis will provide a unique vision of how plants process multiple signals to coordinate their development.