ACQUISITION OF THERMOTOLERANCE IN SACCHAROMYCES-CEREVISIAE WITHOUT HEAT-SHOCK PROTEIN HSP-104 AND IN THE ABSENCE OF PROTEIN-SYNTHESIS

Acquisition of thermotolerance in response to a preconditioning heat treatment at 40-degrees-C was studied in mutants of the yeast Saccharomyces cerevisiae lacking a specific heat shock protein or the ability to synthesize proteins at 40-degrees-C. A mutant carrying a deletion of heat shock protein hsp104 and the corresponding wildtype strain were both highly sensitive to heat stress at 50.4-degrees-C without preconditioning but both acquired almost the same level of thermotolerance after 60 min of preconditioning. Both strains showed equal induction of trehalose-6-phosphate synthase and accumulated equal levels of trehalose during the treatment. The conditional mutant ts - 187 synthesized no proteins during the preconditioning heat treatment but nevertheless acquired thermotolerance, albeit to a lesser degree than the corresponding wildtype strain. Induction of trehalose-6-phosphate synthase and accumulation of trehalose were reduced to a similar extent. These results show that acquisition of thermotolerance and accumulation of trehalose are closely correlated during heat preconditioning and are modulated by protein synthesis but do not require it.