Thermoprotection of chlorophyll biosynthesis enzymes mediated by molecular chaperones

• Applicant: Professor Dr. Felix Willmund, since 1/2023
• Subject Area: Plant Physiology
• Term: since 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 436412227

Temperature is an essential environmental factor that significantly determines plant development and crop yield. Increased temperature owing to climate changes poses a serious threat to protein homeostasis by causing misfolding and/or denaturation of proteins. Chlorophyll (Chl) is the predominant photosynthetic pigment embedded into the various light-harvesting Chl a/b-binding proteins (LHCPs) and the core proteins of the photosystems PSI and PSII, allowing plants and green algae to absorb solar energy. Newly synthesized Chl must be timely incorporated into the Chl-binding proteins, as Chl is essential for correct folding and assembly of the Chl-binding proteins while accumulating free Chls will generate reactive oxygen species upon illumination and thus introduce irreversible photooxidative damage to living cells. Therefore, various auxiliary factors are required to ensure optimized Chl biosynthesis and to synchronize Chl biosynthesis with the biogenesis of the photosystem-antenna complexes during chloroplast development and stress response. However, little is known about the function of molecular chaperones in the regulation of Chl biosynthesis during leaf greening and heat stress. This project is aimed to address the regulatory function of chloroplast-localized molecular chaperones, including the chloroplast signal recognition particle 43 (cpSR43) and two DnaJ proteins CHAPERONE-LIKE PROTEIN OF POR1 (CPP1) and ORANGE (OR), in the Chl biosynthesis pathway. It is hypothesized that molecular chaperone-mediated quality control of chloroplast proteins is essential for proper chloroplast development and heat stress tolerance. Employing the model plant Arabidopsis thaliana, methods in genetics, plant physiology, molecular biology, and biochemistry will be applied to systematically investigate three chloroplast chaperones for the posttranslational control of Chl biosynthesis enzymes.

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Professor Peng Wang, Ph.D., until 12/2022