The two Pseudomonas aeruginosa DksA stringent response proteins are largely interchangeable at the whole transcriptome level and in the control of virulence‐related traits

Summary The stringent response regulator DksA plays a key role in Gram negative bacteria adaptation to challenging environments. Intriguingly, the plant and human pathogen Pseudomonas aeruginosa is unique as it expresses two functional DksA paralogs: DksA1 and DksA2. However, the role of DksA2 in P . aeruginosa adaptive strategies has been poorly investigated so far. Here, RNA‐Seq analysis and phenotypic assays showed that P . aeruginosa DksA1 and DksA2 proteins are largely interchangeable. Relative to wild type P . aeruginosa , transcription of 1779 genes was altered in a dksA1 dksA2 double mutant, and the wild type expression level of ≥90% of these genes was restored by in trans complementation with either dksA1 or dksA2 . Interestingly, the expression of a small sub‐set of genes seems to be preferentially or exclusively complemented by either dksA1 or dksA2 . In addition, evidence has been provided that the DksA‐dependent regulation of virulence genes expression is independent and hierarchically dominant over two major P . aeruginosa regulatory circuits, i.e ., quorum sensing and cyclic‐di‐GMP signalling systems. Our findings support the prominent role of both DksA paralogs in P . aeruginosa environmental adaptation.