Quorum sensing regulation by the nitrogen phosphotransferase system in Pseudomonas aeruginosa

This study was conducted to learn the transcriptional effects of deleting different components of the nitrogen-related phosphotransfer system (Nitro-PTS or PTS-Ntr) in Pseudomonas aeruginosa under infection-similar culture conditions using synthetic cystic fibrosis sputum medium (SCFM2). This system regulates a number of different genes and processes in different bacterial species, but few of its targets have been identified in P. aeruginosa. Because PtsP is required for PtsN phosphorylation, the ptsP mutant provides an opportunity to assess the impact of unphosphorylated PtsN (versus the ptsP ptsN double deletion). We also tested the transcriptional impact of adding 7.5 mM supplementary citrate to this medium. The different deletions showed distinct sets of differentially regulated genes that help yield insight into how the different components of the Nitro-PTS differentially influence expression. The results also aided in identifying previously unrecognized citrate transport proteins. Overall design: Total RNA was extracted using an NEB Monarch kit from bacterial samples grown in liquid synthetic cystic fibrosis sputum medium (SCFM2). Transcriptomes from wild-type P. aeruginosa PA14 were compared with isogenic in-frame deletions of ptsP, ptsP, ptsN, or ptsP + ptsN or with wild-type PA14 grown in SCFM2+7.5 mM citrate.