FIG 1.

The addition of cystine immediately sensitizes sulfate-grown cells to H₂O₂. Exponentially growing E. coli strains were cultured for 5 generations in medium either containing sulfate alone or supplemented with cystine. They were then diluted into the same medium with or without cystine addition for 3 min, and then 2.5 mM H₂O₂ was added. At the indicated time points, the H₂O₂ exposure was terminated by the addition of catalase, and cell viability was determined by plating on LB medium (A) or defined medium (B). (A) Representative time courses. (B) Survival at 5-min time point, with standard deviations from three independent experiments. WT, wild type, AB1157; ΔgshA, JTG10; ΔydjN, KCI1137; ΔfliY, KCI1142; ΔydjN ΔfliY, KCI1160; ΔydjN ΔfliY + p(ydjN), KCI1281.