Stress Responses of the Escherichia coli groE Promoter

GroEL is well known as a molecular chaperone. In order to determine the dynamic stress response of the Escherichia coli groE promoter, a groE-lacZ operon fusion in the chromosome was constructed. Stress leading to σ 32 synthesis induces transcription from E. coli groE promoter, since the promoter is σ 32 -regulated. When the strain was stressed with ethanol, phenol, and sodium chloride, clear inductions of β-galactosidase were observed. Two types of simultaneous stresses of sodium chloride and phenol induced the enzme much more than either of the two alone, suggesting that stress was an additive. The combined stress resulted in the highest induction of the enzyme in this system. The groE-lacZ fusion strain developed in this study can conveniently be used to detect other harmful pollutants in the environment. Stress treatment of cells containing recombinant proteins, which need GroEL, by ethanol, phenol, or sodium chloride, might have a tendency to increase their biological activities.