Schematic representation of oxidative stress metabolism and regulatory network in C. jejuni. The oxidants are highlighted in red; the anti-oxidant proteins are boxed in blue; and the transcriptional regulators, Fur and PerR, are boxed in green and gray, respectively. SodB catalyzes the dismutation of superoxide anion (.O2) to hydrogen peroxide (H2O2). KatA reduces H2O2 to water and oxygen. AhpC catalyzes the reduction of organic hydroperoxide (ROOH) and H2O2 to their corresponding alcohols. Note that H2O2 reduction is primarily catalyzed by KatA (blue arrow) and secondarily by AhpC (dashed blue arrow). Intracellular iron reacts with H2O2 and ROOH to produce hydroxyl radicals (.OH) and alkoxyl radicals (RO.), the two most toxic ROS. Fe2+-Fur is the primary repressor of iron-acquisition pathways (green lines), including ChuABCD, and is the secondary repressor of KatA (dashed green line). Fe2+-PerR is the primary repressor of KatA and AhpC (gray lines), and the secondary repressor of ChuABCD (dashed gray line). H2O2 disrupts the ability of PerR to act as a repressor. Iron represses PerR through an unidentified pathway. Heme is transported by ChuABCD and is required for KatA activity.