Intracellular proteases have many functions and must be highly selective in recognizing their substrates. This project concerns the function and substrates of the essential plastid localized Clp protease machinery in Arabidopsis. The ClpPR protease is a double ring shaped complex containing 10 different ClpPR proteins, most of which are essential for embryogenesis or seedling development. Attached to the barrel are small ClpS1,2 proteins with unknown function and unique to photosynthetic organisms. Clp substrates and substrate recognition mechanisms in plastids are unknown. The objectives are: i) to determine which ClpPR proteins are essential for embryogenesis or seedling development, by completion of genetic analysis of ClpPR mutants. Possible functional redundancy within the ClpR family will be further tested, ii) to carry out targeted biochemical experiments using the clpr2-1 mutant to understand the role of ClpPR complex in plastid gene expression and protein homeostasis, iii) to determine the composition of the asymmetric structure of the ClpPRS complex by biochemical analysis of purified Clp complexes, iv) to identify Clp protease substrates, their degradation signals and specificity of chaperone delivery systems to the ClpPR core complex. Broader impacts: This project will help to determine the molecular function and organization of the Clp protease system, as well as its substrates and substrate recognition mechanisms. Understanding the role of the Clp proteolytic machinery and substrate recognition signals is also critical to control protein stability with the objective to improve the plastid as the site for overproduction of foreign proteins with e.g nutritional or pharmaceutical value (e.g. edible vaccines). The research will provide multi-disciplinary training in plant molecular genetics and biochemistry at the undergraduate, graduate and post-doctoral levels. The PI and co-PI will also participate in curriculum development workshops for high school teachers to develop genomics-based modules for the classroom.
