5′ untranslated region of the Pseudomonas putida WCS358 stationary phase sigma factor rpoS mRNA is involved in RpoS translational regulation

The σS subunit of RNA polymerase is a central regulator which governs the expression of a host of stationary phase-induced and osmotically regulated genes in Gram-negative bacteria. The Pseudomonas putida rpoS gene is transcribed as a monocistronic rpoS mRNA with a 368 nucleotide-long 5′ untranslated region (5′ UTR). In this study, we investigate the posttranscriptional control of RpoS synthesis using rpoS-lacZ transcriptional and translational fusions consisting of the native promoter and deletions of 5′ UTR or insertion into UTR. The differing activity of constructed translational fusions strongly indicated that the 5′ UTR is involved in the translational regulation of RpoS expression in the stationary phase. The results obtained herein demonstrated that the structure of UTR performs an important function in the translational regulation of the rpoS gene.