Molecular Mechanisms of Protein Association with Plastoglobule Lipid Droplets

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This project will explore the mechanisms of protein association with plastoglobules, lipid droplets that exist in the photosynthetic compartment of plant cells. Accumulated evidence indicates that plastoglobules are highly important for effective plant tolerance to a range of environmental stresses. However, it remains unclear what role they play in the cell to facilitate stress tolerance within plants. This research will unravel the relationship between plastoglobule function and stress tolerance by uncovering principles governing the establishment and dynamic regulation of the plastoglobule protein set. Results from this research may provide a foundation for development of agricultural and horticultural crops that are more nutritious and more resilient to environmental challenges. This project will provide scientific training to researchers of diverse backgrounds and career stages. Lesson materials and in-class demonstrations for elementary school students will be developed based on concepts and results of the project that will serve thousands of children from highly diverse socioeconomic and ethnic groups. These lessons will educate students about the value of plants as a source of food, the challenges plants face in nature, and the role of plant science in overcoming these challenges.Dozens of structural and enzymatic proteins associate peripherally at the surface of plastoglobule lipid droplets of chloroplasts. Most of these plastoglobule-associated proteins are known to specifically associate to the plastoglobule, although the molecular mechanisms which underlie this remarkable specificity are unknown. This project will employ integrated biochemical and microscopic techniques to uncover mechanistic principles governing the specific association of proteins. Sequence regions necessary for plastoglobule association will be identified by testing fluorescent localization of truncated and site-directed mutagenized proteins. Lipid-binding capabilities of proteins and relevant sequence regions will be investigated using lipid overlay and vesicle-binding experiments. To determine the impact of post-translational modifications on plastoglobule association, coupled top-down and bottom-up proteomics will be conducted on isolated chloroplast sub-compartments. The research will develop understanding of protein-membrane interactions at a mechanistic level, with implications for all domains of life, particularly other curved or monolayer membranes such as cytoplasmic lipid droplets, micelles, or lipoprotein particles.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.