Loss of heat‐shock acquisition of thermotolerance in yeast is not correlated with loss of heat‐shock proteins

Abstract

Yeast cells when subjected to a primary heat shock, defined as a temperature shift from 23 to 37° for 30 min, acquired tolerance to heat stress (52°C/5 min). Primary heat shocked cells incubated at 23°C for up to 3 h, progressively lost thermotolerance but retained high levels of the major heat‐shock proteins as observed on polyacrylamide gels. On the other hand, a temperature shift back up to 37°C for 30 min fully restored thermotolerance. The major high‐molecular‐mass heat‐shock proteins (hsp) identified were of approximate molecular mass 100 kDa (hsp 100), 80 kDa (hsp 80) and 70 kDa (hsp 70). The results indicate that loss of heat‐shock acquisition of thermotolerance is not correlated with loss of heat‐shock proteins.