The normally silent σ 54 promoters upstream of the pilE genes of both Neisseria gonorrhoeae and Neisseria meningitidis are functional when transferred to Pseudomonas aeruginosa

The pilE gene encodes the pilin subunit in Neisseria gonorrhoeae and Neisseria meningitidis. Transcriptional analysis of promoters upstream of pilE in N. gonorrhoeae has been described previously ( Fyfe et al. (1995) J. Bacteriol. 177, 3781–3787). Transcription from the σ 54 -dependent promoter P3 was detected in Pseudomonas aeruginosa. Here we show that this transcription is dependent on the P. aeruginosa transcriptional activator PilR, and a specific upstream sequence with a high degree of similarity to the PilR-binding site found upstream of the P. aeruginosa pilin gene. This implies there is an upstream activator site ( UAS ) present 5′ of pilE. Sequencing upstream of the N. meningitidis MC58 ¢2 pilE gene shows this region to be very similar to that in N. gonorrhoeae. P3 and the UAS are conserved, although insertions were noted on either side of the UAS. Transcriptional analysis has shown that the N. meningitidis P3 promoter is used in P. aeruginosa, provided PilR and an upstream region that includes sequence similar to the UAS are present. Transcription from the N. meningitidis PpilE is stronger than from the N. gonorrhoeae equivalent. N. meningitidis uses the σ 70 promoter P1 to transcribe pilE.