Acquisition of thermotolerance in Saccharomyces cerevisiae without heat shock protein hsp104 and in the absence of protein synthesis

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Abstract
Acquisiton of thermotolerance in response to a preconditioning heat treatment at 40°C was studied in mutants of the yeast Saccharomyces cerevisiae lacking a specific heat shock protein or the ability to synthesize proteins at 40°C. A mutant carrying a deletion or heat shock protein hsp104 and the corresponding wildtype strain were both highly sensitive to heat stress at 50.4°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.