Figure 9.

Model for the effect of heme on CP-mediated iron starvation in Pseudomonas aeruginosa based on Zygiel et al. (22) and the current work. (Left) When heme is unavailable, CP inhibits P. aeruginosa iron uptake and induces iron-starvation responses including increased siderophore production, inhibition of antR translation, and inhibition of phenazine production. (Right) When heme is available, P. aeruginosa can utilize heme to mitigate the effect of CP on iron uptake, which alleviates its iron-starvation responses to CP. Inhibition of phenazine production by CP is maintained in the presence of heme. Figure S8 provides a model for the effect of heme on CP-mediated iron starvation in Staphylococcus aureus based on the iron-starvation responses observed in this work. CP, calprotectin; IM, inner membrane; OM, outer membrane.