Figure 3
Vacuolar pH plays a critical role in maintaining copper homeostasis. (A) Dose–response matrix measuring the combinatorial effects of CuSO4 and media pH on respiratory growth. BY4743 was grown in buffered YPE media of increasing pH (see top), in multiple concentrations of CuSO4 (see right). Optical density (i.e. OD600, y-axis) of each culture is plotted over time (x-axis). Samples are color-coded according to growth relative to that in pH 4.5 for each copper concentration (see asterisks and grey curves). Data in blue and yellow boxes were used for the dose–response curve in B. (B) Dose–response curves measuring the effect of increasing media pH (indicated on x-axis) on respiratory growth in the presence (red) or absence (black) of 1333 μM CuSO4. Growth relative to that in pH 4.5 is plotted on the y-axis. The mean of three replicates is plotted; error bars represent the standard deviation. (C and D) as in (A and B), only examining the combinatorial effects of CuSO4 and bafilomycin A1 (a specific inhibitor of vacuolar H+−ATPase) on growth in unbuffered YPE media.