CRC-TRR 175/1: Chloropast Ribonucleoproteins – Stabilizing Chloroplast RNA Pools During Acclimation Responses (SP A02)

Chloroplast ribonucleoproteins (cpRNPs) are light-and temperature-regulated phosphoproteins. We have recently demonstrated that cpRNPs impact chloroplast mRNA accumulation and processing under low temperature conditions on an organelle-wide scale. We propose to address the following questions: What is the molecular mechanism of cpRNP action, in particular, what are the exact binding sites on chloroplast mRNAs? How does phosphorylation impact the role of cpRNPs and what are the kinases linking cpRNPs to external signals? And most importantly: How do RNA-pools bound by cpRNPs respond to acclimation processes? We intend to run a two-pronged approach: In a first part, we will conduct mechanistic studies on the role of CP31A and CP29A for cold acclimation using (i) genome-wide quantitative profiling of cpRNP RNA ligands (iCLIP), (ii) genetic analyses of the role of cpRNP phosphorylation and (iii) identification of cpRNP kinases. In the second part, we will contribute to the joined CRC/Transregio effort to quantify PGE during light- and temperature acclimation in tobacco. Our task will be to quantify cpRNP-bound RNA pools, determine RNA editing and analyse protein accumulation by quantitative western analyses and thus to contribute to the identification of truly regulated, i.e. rate-limiting steps in PGE.