An AT-rich tract containing an integration host factor-binding domain and two UP-like elements enhances transcription from the pilEp1 promoter of Neisseria gonorrhoeae.

The pilE gene of Neisseria gonorrhoeae is transcribed from a sigma70 promoter (pilEp1) with an AT-rich tract extending 65 nucleotides upstream of the -35 box. Within this region is an integration host factor (IHF)-binding core consensus sequence. We have performed a detailed analysis to determine which upstream sequences are required for efficient transcription from pilEp1 in N. gonorrhoeae. Deletion of sequences upstream of the AT-rich tract had no effect on the level of transcription. However, the IHF-binding core consensus sequence and the AT-rich sequence further upstream were both required for enhanced levels of transcription from this promoter in both N. gonorrhoeae and an Escherichia coli strain producing IHF. In addition, an UP-like element positioned between the -35 box and the IHF-binding site was required for maximal transcription. The AT-rich region upstream of the IHF-binding core consensus sequence can also act as an UP-like element when appropriately repositioned upstream of the -35 box.