Figure 3. Frp1 and Frp2 participate in the uptake of heme homologs.

(A) FRP1 and FRP2 are differentially required for sensitivity to toxic heme homologs. The indicated strains were diluted in YPD medium with different concentrations of metal-protoporphyrin IX compounds, as indicated, and grown in 96-well plates at 30°C for 2 days. The graph points indicate the averages of triplicate cultures, and the standard deviations are indicated by vertical bars. The strains used are KC590 (WT), KC966 (frp1^-/-), KC1053 (frp2^-/-), KC1061 (frp1^-/- frp2^-/-). (B) Expression of either FRP1 or FRP2 is sufficient to enable ZnMP uptake. Wild-type strain KC2 (WT), strain KC1080 that has a single FRP1 gene under the SSB1 promoter (SSB1p-FRP1) and strain KC1244 that has a single FRP2 gene under the SSB1 promoter (SSB1p-FRP2) were grown in YPD to log phase, then exposed to 1 mM ZnMP for 10 min, washed and visualized by epifluorescence microscopy. Scale bar = 5 μm.

Figure 3—figure supplement 1. Pga7 is not required for sensitivity to non-iron metalloprotoporphyrins (MPPs).

A pga7^-/- strain was transformed with either a vector plasmid (KC646) or with a PGA7-containing plasmid (KC647). The strains were diluted in YPD medium supplemented with 1 mM ferrozine, and with the MPP at the indicated concentrations, and grown in triplicate cultures at 30°C. Each datapoint indicates the average of the triplicate cultures, and the vertical bars indicate the standard deviations.

Figure 3—figure supplement 2. Hemin competes with zinc-mesoporphyrin for uptake by Candida albicans cells.

A wild-type strain was grown for 4 hr in YPD + 1 mM ferrozine to induce expression of the heme uptake system, then the cells were exposed for 10 min to 1 μM zinc-mesoporphyrin, without or with the indicated amounts of hemin. The cells were then washed twice in phosphate-buffered saline and visualized by epifluorescence microscopy with a rhodamine filter set. Scale bar = 5 μm.