The new title of this PhD research is: Trehalose-6-phosphate signaling in Arabidopsis.

Plants require minute sensing of internal and external cues to dynamically adapt to changing environmental conditions. SnRK1 is a kinase complex at the centre of this process and is activated by low-energy stress conditions to ensure energetic homeostasis. By mapping the protein interaction landscape of SnRK1 through affinity purification and proximity labelling mass spectrometry, we identified class II TPS proteins as stable interactors of the kinase complex and further investigation has shown them to be inhibitors of SnRK1 signalling. Arabidopsis encodes seven of these class II TPS proteins and all seven harbour conserved residues that may constitute a T6P binding site, yet they show no metabolic activity towards T6P.

As T6P is a signal metabolite functioning as a proxy for sucrose and as it is a known inhibitor of SnRK1 activity, we hypothesize that T6P exerts its effects on SnRK1 – at least in part – through binding to class II TPS proteins.

The two research lines we focus on are on the one hand Class II TPS proteins, which are putative T6P sensors regulating SnRK1, and on the other hand the putative TPS1-regulatory function of Fantastic Four (FAF) 1-4, which may couple sucrose levels to T6P biosynthesis.