Formation of pilin in Pseudomonas aeruginosa requires the alternative σ factor (RpoN) of RNA polymerase

Abstract

The promoter region of the Pseudomonas aeruginosa pilin gene has a high degree of similarity to the nitrogen-regulated promoters of enteric bacteria. These promoters are recognized by the alternative σ factor of RNA polymerase, termed RpoN (NtrA or GlnF). This observation suggested that the P. aeruginosa pilin gene may be transcribed by the RpoN-containing RNA polymerase. We, therefore, cloned the RpoN gene from P. aeruginosa into Escherichia coli (where it formed a functional product) and used that cloned gene to construct a mutant of P. aeruginosa that was insertionally inactivated in its RpoN gene. This mutant failed to synthesize pilin, indicating that the RpoN σ factor is required for transcription of the pilin gene.