Transient shut off of Escherichia coli heat shock protein synthesis upon temperature shift down.

A moderate downward shift in growth temperature (37 to 30 degrees C in strain B/r and 37 to 24 degrees C in strain K-12) was found to depress markedly the synthesis of major heat shock proteins GroEL and DnaK in E. coli. The depression was transient and cancelled gradually to a new steady state level, taking 60-80 min. The synthesis of beta-galactosidase directed by transcription initiated at the groE promoter behaved similarly, suggesting that this regulation, termed "reverse heat shock response", occurs at the transcriptional level.