Acyadeletion mutant ofEscherichia colidevelops thermotolerance but does not exhibit a heat-shock response

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Abstract
Summary: An adenyl cyclase deletion mutant (cya) ofE. colifailed to exhibit a heat-shock response even after 30 min at 42 °C. Under these conditions, heat-shock protein synthesis was induced by 10 min in the wild-type strain. These results suggest that synthesis of heat-shock proteins inE. colirequires thecyagene. This hypothesis is supported by the finding that a presumptive cyclic AMP receptor protein (CRP) binding site exists within the promotor region of theE. coli htp Rgene. In spite of the absence of heat-shock protein synthesis, when treated at 50 °C, thecyamutant is relatively more heat resistant than wild type. Furthermore, when heat shocked at 42 °C prior to exposure at 50 °C, thecyamutant developed thermotolerance. These results suggest that heat-shock protein synthesis is not essential for development of thermotolerance inE. coli.