GaPPIX and ZnPPIX inhibit S. aureus aerobic respiration and are trafficked to the plasmid membrane. (A) ICP-MS tracking of GaPPIX in S. aureus. Percentage of total gallium atoms measured in the cell wall (W), membrane (M), and cytoplasmic (C) fractions. Error bars represent the standard deviation from three independent samples. Asterisks represent statistically significant differences between GaPPIX and Ga(NO3)3 localization, as determined by a Student t test (*, P < 0.02; **, P < 0.05). (B) Mean ratio of red/green fluorescence of S. aureus grown to mid-exponential phase and incubated with 30 µM of the dye 3′3′-diethyloxacarbocyanine iodide (DiOC2). The average from three independent experiments is shown. Error bars represent one standard deviation from the mean. (C) Measurement of d- and l-lactate in the supernatants of S. aureus grown in the presence of GaPPIX or ZnPPIX after 15 h of growth. The amount of d- and l-lactate accumulated in the supernatants of anaerobically grown S. aureus is also presented for comparison. The average from three independent experiments is shown. Error bars represent one standard deviation from the mean. (D) ICP-MS tracking of GaPPIX in S. aureus (WT) and the isogenic cydB qoxB mutant. Percentage of total gallium atoms measured in the cell wall (W), membrane (M), and cytoplasmic (C) fractions. Error bars represent the standard deviation from three independent samples. Asterisks represent statistically significant differences between GaPPIX and Ga(NO3)3 localization, as determined by a Student t test (*, P < 0.003).