Figure 1.

Model for the σ^E cell envelope stress response. Expression of the gene encoding σ^E (sigE) is regulated at the level of transcription by the CseB/CseC two‐component signal transduction system. In response to signals originating in the cell envelope when it is under stress, the sensor kinase, CseC, becomes autophosphorylated and transfers this phosphate to the response regulator, CseB. Phospho‐CseB activates the promoter of the sigE operon, and σ^E is recruited by core RNA polymerase to transcribe its regulon. Note that >90% transcription from the sigE promoter terminates just downstream of sigE and that the promoter of the sigE gene itself is not a σ^E target. CseA is a lipoprotein localised to the extracytoplasmic face of the cell membrane and loss of the CseA results in upregulation of the sigE promoter.