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Activation and Regulation of SENSITIVE TO FREEZING 2, a Chloroplast-Remodeling Enzyme
During times of stress, plants remodel their membranes to survive. SENSITIVE TO FREEZING 2 (SFR2) is a chloroplast-remodeling enzyme activated in response to cellular stress. SFR2 uses monogalactosyldiacylglycerol (MGDG) to create oligogalactolipids and triacylglycerol (TAG). In doing so, it removes lipids that are not ideal for membrane formation and creates lipids that help prevent membrane leakage and shrinkage. SFR2 protein is always present, but not always active. It activates in response to cytosolic acidification that occurs during freezing, among other abiotic stresses. The goal of this dissertation is to elucidate the specific mechanism of activation. Chapter 1 reviews both past and current literature and findings with respect to SFR2. Chapter 2 investigates SFR2’s activation through cytosolic acidification and compares lipid changes during acidification to lipid changes during freezing stress. In Chapter 3 employs protoplasts as a tool to understand how cellular damage activates SFR2. Chapter 4 uses diverse plant species to study how SFR2 has changed across plant evolution and explores how plants of varying cold tolerance use SFR2. Lastly, in Chapter 5, SFR2 is analyzed at the protein level, identifying specific residues that change under SFR2 activation, and search for the source of SFR2’s activating protons.
Barnes, Allison Claire, "Activation and Regulation of SENSITIVE TO FREEZING 2, a Chloroplast-Remodeling Enzyme" (2019). ETD collection for University of Nebraska - Lincoln. AAI13859469.