Characterization of Inducible HSP70 Genes in an Antarctic Yeast, PI12, in Response to Thermal Stress.

The induction of highly conserved heat shock protein 70 (HSP70) is often related to a cellular response due to harmful stress or adverse life conditions. In this study, we determined the expression of genes in the Antarctic yeast, , under different several thermal treatments for several exposure periods. The main aims of the present study were (1) to determine if stress-induced could be used to monitor the exposure of the yeast species to various types of thermal stress; (2) to analyze the structures of the HSP70 proteins using comparative modeling; and (3) to evaluate the relationship between the function and structure of HSP70 in . In this study, we managed to amplify and clone 2 genes from named and . The cells of expressed significantly inducible genes after the heat and cold shock treatments. Interestingly, showed 2-6-fold higher expression than after the heat and cold exposure. ATP hydrolysis analysis on both HSP70s proved that these psychrophilic chaperones can perform activities in a wide range of temperatures, such as at 37, 25, 15, and 4 °C. The 3D structures of both HSP70s revealed several interesting findings, such as the substitution of a β-sheet to loop in the N-terminal ATPase binding domain and some modest residue substitutions, which gave the proteins the flexibility to function at low temperatures and retain their functional activity at ambient temperatures. In conclusion, both analyzed HSP70s played important roles in the physiological adaptation of .