Genetic control of heat-shock protein synthesis and its bearing on growth and thermal resistance in Escherichia coli K-12.

When Escherichia coli cells grown at 30 degrees C are transferred to 42 degrees C, synthesis of several polypeptides is markedly and transiently induced. A temperature-sensitive nonsense mutant (tsn-K165) of E. coli K-12 is found to be defective in the induction of these proteins. mRNA for one major heat-shock polypeptide (groE protein) tested is induced in the wild type but not in the mutant upon temperature shift. Hence, the mutation defines a (regulatory) gene, designated hin (heat shock induction), whose product is required for active transcription of a set of heat-inducible operons in E. coli. The results reported herein suggest that the heat-shock polypeptides controlled by the hin gene play an important role in cell growth at high temperature. The possible involvement of the hin gene product in protection against thermal killing is also discussed.