CRC/TRR 175/1: Role of Reversible Phosphorylation of GUN4 in Acclimation, Retrograde Signalling and Tetrapyrrole Biosynthesis (SP C04)

In oxygenic photoautotrophs, GENOMES UNCOUPLED 4 (GUN4) is an essential stimulator of Mg-chelatase and its phosphorylation lowers the MgCh activity leading to attenuation of Proto consumption for chlorophyll biosynthesis. The objectives of this project include examination (i) of the impact of GUN4 phosphorylation on optimized environmental acclimation for chlorophyll biosynthesis and plastid retrograde signaling and vice versa (ii) of the molecular control mechanisms of GUN4 phosphorylation in response to changing light and temperature conditions and acclimation. To the end the molecular mechanisms of the modulated action of phosphorylated GUN4 will be examined in-vitro and in-planta and the GUN4 protein kinase identified.