Data for: Post-translational regulation of photosynthetic activity via the TOR kinase in plants

Chloroplasts are the powerhouse of the plant cell, and their activity must be matched to plant growth to avoid photo-oxidative damage. We have identified a post-translational mechanism linking the eukaryotic Target of Rapamycin (TOR) kinase that promotes growth and the guanosine tetraphosphate (ppGpp) signaling pathway of prokaryotic origins that regulates chloroplast activity, and photosynthesis in particular. We find that RelA SpoT Homologue 3 (RSH3), a nuclear-encoded enzyme responsible for ppGpp biosynthesis, interacts directly with the TOR complex via a plant-specific N-terminal region which is phosphorylated in a TOR-dependent manner. Downregulating TOR activity causes a rapid increase in ppGpp synthesis in RSH3 overexpressors and reduces photosynthetic capacity in an RSH-dependent manner in wild-type plants. The TOR-RSH3 signaling axis therefore regulates the equilibrium between chloroplast activity and plant growth, setting a precedent for the regulation of organellar function by TOR.