Novel target genes of PsrA transcriptional regulator of Pseudomonas aeruginosa

The PsrA transcriptional regulator is involved in stationary phase induced transcriptional regulation of rpoS and in negative auto-regulation in Pseudomonas aeruginosa. This study was designed to determine whether other loci were regulated by PsrA in P. aeruginosa. Computer search was performed of the PsrA binding motif (G/CAAAC N 2–4 GTTTG/C) against the P. aeruginosa genome sequence. Four of 14 analysed promoters responded to and bound PsrA; (i) divergent promoters controlling PA2952/PA2951 and PA2953, (ii) promoter of PA0506 and (iii) upstream region of PA3571. Promoters PA0506 and PA2952–PA2951 were regulated negatively whereas promoters of PA2953 and PA3571 were regulated positively by PsrA. Two dimensional sodium dodecyl sulphate polyacrylamide gel electrophoresis (2D SDS-PAGE) analysis on total proteins from P. aeruginosa PAO1 and psrA knock-out derivative was also performed resulting in the identification of 11 protein spots which were differentially regulated. These studies have indicated PsrA as a global regulator.