FIG 10.

YbeY regulates the bacterial response to oxidative stresses and virulence through ReaL and RpoS. (A) The indicated strains were grown in LB to an OD₆₀₀ of 1 and then incubated with or without 2 mM H₂O₂ for 30 min. The bacteria were collected by centrifugation, and the cells were broken by sonication. The total intracellular catalase activity was measured using a catalase assay kit. (B) The indicated strains were grown in LB to an OD₆₀₀ of 1, and the cells were washed three times with PBS and then incubated with 10, 20, or 50 mM H₂O₂ for 30 min. The bacteria were collected by centrifugation and resuspended with fresh LB, and the survival rates were determined by plating. (C) The indicated strains were incubated with dHL60 cells at an MOI of 5 in HBSS for 3 h. The bacterial survival rates were determined by plating. (D) Mice were infected intranasally with the indicated strains. At 12 h postinfection, lungs from the infected mice were isolated. The bacterial loads were determined by serial dilution and plating. ns, not significant; **, P < 0.01; ***, P < 0.001 by Student’s t test.