The Catalase-Peroxidase KatG Is Required for Virulence of Xanthomonas campestris pv. campestris in a Host Plant by Providing Protection against Low Levels of H2O2

Xanthomonas campestris pv. campestris katG encodes a catalase-peroxidase that has a role in protecting the bacterium against micromolar concentrations of H2O2. A knockout mutation in katG that causes loss of catalase-peroxidase activity correlates with increased susceptibility to H2O2 and a superoxide generator and is avirulent in a plant model system. katG expression is induced by oxidants in an OxyR-dependent manner.