Fig. 4

Function of DnaK in association with σ^H in response to heat stress. Unfolded proteins caused by heat stress are sensed by the heat shock chaperon DnaK which keeps attached to σ^H. Upon protein unfolding, DnaK releases σ^H which in turn binds to RNA polymerase. The σ^H—RNA polymerase complex transcribes genes whose products are essential to respond against the cytoplasmic stress. This is to be mentioned that the transcription of the σ^H (encoded by the rpoH gene) is induced at elevated temperature via the action of σ^E (encoded by the rpoE gene)