The Catalase KatA Contributes to Microaerophilic H(2)O(2) Priming to Acquire an Improved Oxidative Stress Resistance in Staphylococcus aureus

Staphylococcus aureus has to cope with oxidative stress during infections. In this study, S. aureus was found to be resistant to 100 mM H(2)O(2) during aerobic growth. While KatA was essential for this high aerobic H(2)O(2) resistance, the peroxiredoxin AhpC contributed to detoxification of 0.4 mM H(2)O(2) in the absence of KatA. In addition, the peroxiredoxins AhpC, Tpx and Bcp were found to be required for detoxification of cumene hydroperoxide (CHP). The high H(2)O(2) tolerance of aerobic S. aureus cells was associated with priming by endogenous H(2)O(2) levels, which was supported by an oxidative shift of the bacillithiol redox potential to −291 mV compared to −310 mV in microaerophilic cells. In contrast, S. aureus could be primed by sub-lethal doses of 100 µM H(2)O(2) during microaerophilic growth to acquire an improved resistance towards the otherwise lethal triggering stimulus of 10 mM H(2)O(2). This microaerophilic priming was dependent on increased KatA activity, whereas aerobic cells showed constitutive high KatA activity. Thus, KatA contributes to the high H(2)O(2) resistance of aerobic cells and to microaerophilic H(2)O(2) priming in order to survive the subsequent lethal triggering doses of H(2)O(2), allowing the adaptation of S. aureus under infections to different oxygen environments.