The molecular analysis of low temperature and freezing stress resistance

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Some fish and insects are protected from freezing by making ice-binding proteins that stick to embryonic ice crystals and prevent ice growth by blocking the addition of more water molecules. Thus, these proteins significantly lower the freezing temperature. However, ice-binding proteins are also found, but little known, in a few organisms such as plants, insects and bacteria that survive even if they are frozen. This proposal first seeks to test if ice-binding proteins are vital for survival, something that has never been done before. Further investigations will determine if the proteins in freeze-tolerant organisms defend against low-temperature pathogens, and if they can help protect host cell membranes at low temperatures. The special properties of these proteins from freeze-tolerant organisms, including (somewhat ironically) their inability to significantly depress the freezing point, makes them especially useful for understanding the mechanisms of ice binding. This is something that cannot be done so easily with the better known, more active proteins from species that do not freeze. Canada's geography and food security demands that in the future, crops will have to be grown further north and so the transfer of freeze-tolerance will have economic benefits. As well, these proteins have medical applications for tissue cryopreservation. Our discovery that ice-binding proteins inhibit dangerous gas hydrates that spontaneously form during gas and oil exploration and transport (with disastrous consequences) means that in the future, the rational design of materials based on these proteins will directly benefit the health and safety of many Canadians. This research program on the molecular analysis of low temperature and freezing stress resistance has been specifically designed for instruction of students and will appeal to young trainees who want to address problems that they see as relevant and compelling.