Schematic presentation of the PerR regulatory oxidative stress response in S. suis . (A) dpr is repressed by PerR, and derepression of dpr could be induced by H2O2. Abundant Dpr stores iron to prevent Fenton reaction. (B) derepression of metQIN is induced by H2O2, leading to increasing Met (methionine) and MetO (methionine sulfoxide) uptake. During Met cyclic oxidation and reduction, H2O2 can be reduced to H2O. (C) FeoAB is negatively regulated by PerR. (The broken lines indicate that the regulatory mechanisms were unclear).