Iron is a crucial micronutrient for Pseudomonas aeruginosa survival and virulence, yet it can also be toxic due to the production of reactive oxygen species. The PrrF small regulatory RNAs (sRNAs) are transcribed in iron-limiting conditions and block the expression of several mRNAs involved in P. aeruginosa's oxidative stress response. Here, we make the surprising discovery that oxidative stress induces expression of the PrrF sRNAs. We also provide evidence that PrrF regulation of two mRNA targets is hindered upon oxidative stress. Oxidative stress similarly induces the PrrF sRNAs in Pseudomonas fluorescens, indicating conservation of this novel regulatory event. This study, therefore, highlights a novel and conserved regulatory link between iron homeostasis and oxidative stress protection in the pseudomonads.
Ouattara et al. (Mon,) studied this question.