The Pseudomonas aeruginosa iron-responsive PrrF small RNAs (sRNAs) exert broad effects on overall physiology and production of virulence traits. The PrrF sRNAs are distinct from many iron-responsive bacterial sRNAs in that two nearly identical PrrF RNAs (PrrF1 and PrrF2) are encoded in tandem on the P. aeruginosa chromosome. This arrangement allows for the expression of an additional, longer RNA, designated PrrH, which is responsive to heme as well as iron. As heme is an abundant source of iron during infection, we hypothesize that this novel RNA imparts unique regulatory functions that are important for pathogenesis.
We are currently working to understand 1) how the PrrH sRNA is expressed and regulated by heme (K22-funded project), and 2) how PrrH regulation contributes to P. aeruginosa physiology and virulence. We are also conducting studies to determine how each of these sRNAs interacts with Hfq, a conserved RNA binding protein that we previously showed interacts with the PrrF and PrrH sRNAs in vivo. Each of these projects involve collaborations with multiple laboratories, and they have already yielded critical data on the role of the PrrF and PrrH sRNAs in iron homeostasis and virulence. We expect that these studies will identify new factors important for P. aeruginosa pathogenesis, which should provide new targets for antimicrobial development.