| Notes |
Results sugget that the dps promoter is recognized by both Sigma70- holoenzyme and SigmaS-holoenzime since OxyR acts on Sigma70, and in addition the starts of the OxyR-and of the SigmaS-dependent transcripts are identical. This promoter displays an unusual form of regulation. If cells are treated with hydrogen peroxide during exponential growth, dps transcription is induced by OxyR, which activates Sigma70-RNA polymerase. Surprisingly, the same promoter is also activated by IHF and SigmaS at the onset of stationary phase. It is assumed that both OxyR and IHF bind upstream of the dps promoter, and that the mechanisms of activation act independently of each other. The promoter has a a sequence that conform to the consensus -10 for , but no obvious -35 sequence is present. Possibly the dps promoter is not ideally bound by either holoenzyme leading to the need for IHF to enhance the binding of SigmaS-RNA polymerase and of OxyR to enhance the binding of Sigma70-RNA polymerase. |