BMOL Thesis Defense: Emily Vernon

Thesis Information

Student: Emily Vernon, M.S. Candidate

Advisor: Dr. Konrad Meister, Chemistry & Biochemistry

Committee Members: Dr. Daniel Fologea (Physics) & Dr. Oliviero Andreussi (Chemistry & Biochemistry)

Title: Effects of Antifreeze Proteins on Lipid Membrane Stabilization at Cold Temperatures

Abstract: Cold-adapted organisms use antifreeze proteins (AFPs) and antifreeze glycoproteins (AFGPs) to enable survival in freezing habitats. AF(G)Ps have been proposed to prevent leakage of intracellular metabolites by stabilizing cellular membranes, a property that could be of great physiological and biomedical relevance. The generality of this effect is not understood, and for the known examples of membrane leakage prevention by AF(G)Ps, the mechanisms remain unclear. Here, we report a comprehensive evaluation of the effects of different AFPs on the leakage of ions and dyes from model membrane systems. We find that leakage is best prevented by AFGPs, while insect AFPs showed negligible effects. Reduction of antifreeze activities of AFGPs further showed no effect on membrane leakage inhibition activities. Thus, the ability to stabilize membranes through phase transitions is not an intrinsic property of AF(G)Ps, and the interactions proceed through protein-specific mechanisms that are decoupled from general antifreeze activities.