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.