Figure 5.

Siderophore-induced relocation of Sit1-GFP.The Sit1Δ cells transformed with pGAL-SIT1-GFP were cultured to midexponential growth phase in raffinose-containing medium. Sit1-GFP synthesis was induced by incubation with galactose for 60 min and was stopped by adding glucose and incubating for 15 min. The sorting of Sit1-GFP from the endosomes to the plasma membrane was assessed A) by fluorescence microscopy and B) by measuring FOB uptake after incubation with the indicated compound for 30 min. For uptake experiments, the cells were rapidly washed with water and filtered before resuspension in minimal glucose medium containing 1 μm⁵⁵Fe-FOB. The iron content of the cells was determined after 10 min of incubation at 30°C. Uptake values (B) are expressed as means ± standard error of the mean for three experiments.