Figure 7.

Oxygen consumption rates of WT, mutant, and dacA suppressor strains. A, schematic representation of the two S. aureus terminal oxidases. The main terminal oxidase Qox (also referred to as cytochrome aa₃) is composed of the proteins QoxA–QoxD and has been suggested to contain heme A and heme B as cofactors (10) and requires the CtaA protein (a membrane protein but shown for simplicity as soluble protein) for heme A biosynthesis. The second terminal oxidase Cyd (also referred to as cytochrome bd) is composed of the proteins CydA and CydB and has been suggested to contain heme B and heme O (10) and therefore likely does not require CtaA for its synthesis. B and C, oxygen consumption rates of WT, mutant, and dacA suppressor strains. The indicated S. aureus strains were grown to mid-log phase, washed, and the oxygen consumption rates of concentrated culture aliquots determined following the addition of glucose. The oxygen consumption rates are plotted as nanomoles of O₂ consumed per min per A₆₀₀ = 1. For each strain, 3–6 biological replicates were used, and the average values and standard deviations of the oxygen consumption rates were plotted. Statistical analysis was performed in Prism (GraphPad) using a Kruskal-Wallis test followed by a Dunn's multiple comparison test. Adjusted p values <0.05 are indicated by a single asterisk and adjusted p values <0.01 by a double asterisk.