The SOS promoter dinH is essential for ftsK transcription during cell division.

The formation of the Escherichia coli division septum has been well characterized and the majority of the genes involved have been shown to map to the dcw cluster. One exception is ftsK, which lies at 20 minutes, immediately downstream of the global response regulatory gene, lrp. The promoter for ftsK has not yet been assigned. Here, it is reported that ftsK is transcribed from two promoters; the first is located within the lrp reading frame and is dispensable whilst the second is essential and corresponds to dinH, previously characterized as an SOS promoter regulated by LexA. ftsK is the first essential gene to be described that is controlled by an SOS-inducible promoter. A possible mechanism by which dinH may be activated in recA minus strains, or in strains with uncleavable LexA, is discussed.