Recent insights into the general stress response regulatory network in Escherichia coli

Many bacterial species exhibit a general stress response that can be induced by numerous very different stress conditions and, phenotypically, renders the cells broadly stress resistant. In Escherichia coli, this response is dependent on the sigma(s) (RpoS) subunit of RNA polymerase. sigma(s) is a close relative of the vegetative sigma factor sigma(70) (RpoD) and recognizes very similar promoter sequences. In recent years, significant progress has been made with respect to elucidating (1) the molecular mechanisms that control the cellular sigma(s) level, which include translational regulation as well as intricate control of sigma(s) proteolysis, and (ii) the molecular function of sigma(s) as a transcription initiation factor, where a number of sigma(s)-dependent promoters have been studied in treat detail, and the mechanisms that generate sigma(s) selectivity are now becoming apparent.