Fig 2. Ctr3 enables H. capsulatum growth in limited copper.

Dose response curves for Ctr3-expressing (CTR3, black), Ctr3-deficient (ctr3, red), and the complemented (ctr3/CTR3, blue) strains grown in liquid culture with the copper-specific chelator BCS (A), the iron-specific chelator BPS (B), and with added CuSO₄ (C). Yeasts were grown in HMM at 37°C in the presence of a gradient of concentrations of BPS, BCS or CuSO₄. Yeast growth was monitored daily by measurement of culture turbidity (optical density at 595 nm) and growth after 5 days normalized to growth of yeasts in the absence of chelators or CuSO₄. Dose-response curves were generated by non-linear regression. IC₅₀ values for growth in BCS were 1,661 μM, 2.8 μM, and 442 μM, for CTR3, ctr3, and ctr3/CTR3, respectively. Data represent the average relative growth ± standard deviation of biological replicates (n = 3).