Induction of Heat Shock Proteins and Thermotolerance

In yeast, as with other organisms, a heat shock causes the induction of the heat shock response. The main consequences of this induction are (at the physiological level) an increased tolerance of high, potentially lethal temperatures, and (at the molecular level) strong induction of a small number of heat shock proteins. The messenger RNAs for the latter proteins are generated by a transcriptional activation of heat-inducible genes. The heat shock response is usually transient, heat shock protein synthesis becoming repressed just a few minutes after an induction by either temperature upshift to stressful temperatures or an upshift followed by a return to normal temperatures (1 ).