suis and showed it in Figure 6. Figure 6 Schematic presentation of the PerR regulatory oxidative stress response in S. suis . (A) dpr is repressed by PerR, and this website derepression of dpr could be induced by H2O2. Abundant Dpr stores iron to prevent INCB024360 in vitro 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). PerR has been found to be necessary for full virulence of S. pyogenes. Our investigation found that the pathogenicity of perR mutant strain was attenuated. The decreased pathogenicity might be due to the reduced viability of mutant in the host. The fact that the viable
number of mutant recovered from mice was much less than that of the wild-type, also supported this explanation. It seems that deletion of perR may lead to inappropriate expression of PerR-regulated IWR-1 mouse genes and affect the normal growth. For example, knockout of perR led to iron starvation and the growth was inhibited in B. subtilis. It was reported that, because Dpr could store iron, the cytosolic iron would be efficiently scavenged when dpr was ectopic overexpressing in S. suis. It suggested that in ΔperR, the derepressed dpr would lead to cytosolic iron starvation and affect the growth. Conclusions These data strongly suggest that the Fur-like protein PerR regulates the oxidative stress response in S. suis. Two members of PerR regulon dpr and metQIN were identified in S. suis, dpr played a crucial role in H2O2 resistance and metQIN might indirectly affect the H2O2 resistance by controlling the methionine uptake. Mice infection model showed that the pathogenicity of perR mutant strain was attenuated. Methods Bacterial strains, plasmids, and growth conditions All the bacterial strains and plasmids used in this study are listed in Table 3. S. suis serotype 2 strain SC-19 was isolated from diseased pigs in Sichuan province, China in 2005 .
S. suis was grown in tryptic soy broth (TSB) or on tryptic soy agar (TSA; Difco, Detroit, MI, USA) plates containing 5% newborn bovine serum (Sijiqing, Hangzhou, China). The CDM , modified when SPTLC1 necessary, was also used to culture S. suis. E. coli strains DH5α and BL21 (DE3) were cultured in/on Luria–Bertani broth or plates (Oxoid, Basingstoke, UK). When necessary, antibiotics were added to the plates or broth at the following concentrations: 100 μg/ml spectinomycin (Spc), 2.5 μg/ml erythromycin (Erm) or 5 μg/ml chloramphenicol for S. suis; 50 μg/ml Spc, 180 μg/ml Erm, 12.5 μg/ml Chl or 50 μg/ml kanamycin  for E. coli. Table 3 Strains and plasmids used in this study Strains or plasmids Characteristics Reference or source Strains SC-19 Virulent Chinese S.