The Streptomyces coelicolor dnaK operon contains a second promoter driving the expression of the negative regulator hspR at physiological temperature

HspR (heat shock protein regulator) acts as a negative regulator of different genes in many bacteria. In Streptomyces coelicolor hspR gene is part and the transcriptional repressor of the dnaK operon which encodes the DnaK, GrpE, DnaJ chaperone machines and HspR itself. Our experiments led us to the discovery of a second promoter, internal to dnaK operon, located upstream hspR gene. Transcription from this promoter was detected at 30°C indicating that hspR could play a key physiological role.