Oral Presentation International Plant Molecular Biology Conference 2024

Targeted interactomics connects the plant SnRK1 kinase with nutrient sensing.   (#392)

Geert De Jaeger 1
  1. VIB Center for Plant Systems Biology, Ghent University, Ghent, Flanders, Belgium

The central metabolic regulator SnRK1 controls plant growth and survival upon activation by energy and nutrient depletion, while also gatekeeping developmental transitions and nutrient allocation between source and sink tissues. Despite significant progress made in recent years, many questions still remain on how SnRK1 senses cellular energy and nutrient levels in plants, and how it translates this information to ensure optimal growth and survival. Therefore, we are mapping proteome-wide SnRK1 signaling networks in Arabidopsis in relation to nutrient availability. We combined phospho-proteomics, affinity purification, proximity labeling and cross linking mass spectrometry to shed light on the interaction landscape, structure and post-translational modification state of the core heterotrimeric SnRK1 kinase complex. Among its targets, we discovered a TPR middelman to mediate SnRK1 dependent chloroplastic starch degradation. At the intersection of this targeted interactomics approach, we discovered a strong association of SnRK1 with class II T6P synthase-like proteins. Biochemical and cellular assays showed that these proteins function as negative regulators of SnRK1, and might have a role as carbon sensors that integrate T6P levels with SnRK1 activity. In parallel we follow a similar approach to explore if SnRK1 also senses nitrogen starvation in the cell, and here we could discover a connection with a receptor in the ER.