Regulatory pathways dependent on the RseP protease in Pseudomonas aeruginosa
The opportunistic pathogen P. aeruginosa is responsible for a wide range of infections and is wide spread in many soils and human surroundings. In order to survive, the bacteria overcome limited iron bio-availability by releasing iron-chelating molecules known as siderophores. RseP, an intramembrane protease is critical for proteolysis of signal transduction proteins in siderophore uptake systems and Extra Cytoplasmic Function (ECF) sigma activity. RseP plays a crucial role in proteolytic cascades which allow complete degradation of anti-sigma factors and control the expression of sigma factor mediated genes in P. aeruginosa. The aim of this study was to identify different genes or pathways that are mediated by RseP protease in P. aeruginosa, particularly new RseP-mediated genes in other pathways than siderophore uptake systems which have already been well characterized. An additional aim was to investigate whether the expression of siderophore receptor genes is altered by overexpressing RseP. The expression of siderophore receptor genes was determined by RT-qPCR analysis in selected RseP mutant strains including overexpressed and knocked out strains. Similar expression of all receptor genes was observed in all the strains including an RseP overexpressing strain and wild-type. Findings of the present study rejected the hypothesis that overexpressed RseP may affect the transcription of siderophore receptor genes. We identified 69 genes which showed a significant differentially expression in overexpressed RseP and RseP knocked out strains by RNA-Seq analysis. Thus, these differentially expressed genes were thought to be RseP-dependent genes. Furthermore, minimal inhibitory concentration (MIC) testing demonstrated that the expression of rseP had no direct effect on the changes in resistance phenotypic of P. aeruginosa.
Advisor: Lamont, Iain
Degree Name: Master of Science
Degree Discipline: Biochemistry
Publisher: University of Otago
Keywords: RseP; Protease; P.aeruginosa
Research Type: Thesis