Pyoverdine, a siderophore from Pseudomonas aeruginosa, translocates into C. elegans, removes iron, and activates a distinct host response.

Pseudomonas aeruginosa is a re-emerging opportunistic pathogen with broad antimicrobial resistance. We have previously reported that the major siderophore pyoverdine from this pathogen disrupts mitochondrial networks and induces a lethal hypoxic response in model host Caernorhabditis elegans. However, the mechanism of such cytotoxicity remained unclear. Here, we demonstrate that pyoverdine translocates into host cells, binding to host ferric iron sources. The reduction of host iron content disrupts mitochondrial function such as NADH oxidation and ATP production and activates mitophagy. This activates a specific immune response that is distinct from colonization-based pathogensis and exposure to downstream pyoverdine effector Exotoxin A. Host response to pyoverdine resembles that of a hypoxic crisis or iron chelator treatment. Furthermore, we demonstrate that pyoverdine is a crucial virulence factor in P. aerguinosa pathogenesis against cystic fibrosis patients; F508 mutation in human CFTR increases susceptibility to pyoverdine-mediated damage.