A novel extracytoplasmic function (ECF) sigma factor regulates virulence in Pseudomonas aeruginosa

Next to the two-component and quorum sensing systems, cell-surface signaling (CSS) has been recently identified as an important regulatory system in Pseudomonas aeruginosa. CSS senses signals from outside the cell and transmits them into the cytoplasm. It consists of a TonB-dependent outer membrane receptor, a cytoplasmic membrane-localized sigma factor regulator (or anti-sigma factor), and an extracytoplasmic function (ECF) sigma factor. Upon perception of the extracellular signal by the receptor the ECF sigma factor is activated and promotes the transcription of a specific set of gene(s). Although most P. aeruginosa ECF sigma factors are involved in the regulation of iron uptake, we have identified a novel ECF sigma factor (PA0675) involved in the regulation of virulence. By microarray analysis of cells overexpressing PA0675 from the pMUM3 plasmid we have identified the genes regulated by this sigma factor. Two different samples are analyzed namely P. aeruginosa (pMMB67EH) (control/reference sample) and P. aeruginosa (pMUM3) (overexpressing the PA0675 ECF sigma factor). Two different replicates per sample are included.