NSF Award
8701197
Ice nuclei can be applied to promote the independent freezing of large numbers of water droplets, and to transduce molecular events into macroscopic signals. Ice nuclei of bacterial origin vary in their critical temperature for activity; the variability is problematic for practical applications, and its cause is not understood. In this research, the ice nucleation gene InaZ is manipulated and its products are analyzed to discover what governs the variability in critical nucleation temperature. Changes in protein concentration, caused by promoter substitutions, are correlated with nucleation frequency; this will indicate the molecularity of the assembly reaction for ice frequency: this will indicate the molecularity of the assembly reaction for ice nuclei over a range of critical temperatures. The subcellular locations of mutant InaZ proteins are determined and compared to their ice nucleation potentials, to reveal relationships between protein primary structure, localization, and function. Domains from heterologous proteins are substituted into the InaZ protein to further explore the requirements for nucleation at the higher end of the range of critical temperatures. The information obtained is utilized in the engineering of ice nucleation proteins with enhanced capacities for forming populations of ice nuclei with uniformly high critical temperatures. The goal of this research is to analyze how the critical temperatures of ice nucleic are determined. This is a thoughtfully concerned and focused research effort dealing with a significant phenomenon of great interest in biology. The implications for frozen food processing, snow making, arctic ice engineering, climate modification and frost control are infinite.
