FIG. 4.

Pvd recycling in P. aeruginosa wild-type and tat mutant strains. PAKΔtatC cells at an OD₆₀₀ of 0.6 were incubated in 50 mM Tris-HCl (pH 8.0) at 29°C. The assay was started by adding 100 nM Pvd-Fe to the cells (○). The increase in fluorescence at 447 nm was monitored by measuring the fluorescence at 450 nm (excitation wavelength, 290 nm) every second for 30 min. The same fluorescence measurements were repeated in the absence of the siderophore (•). a.u., arbitrary units.