FIG 3.

Exogenous spermidine restores colibactin-associated genotoxicity in a ΔspeE mutant. Colibactin-mediated genotoxicity was determined by infection of HeLa cells with E. coli strain DH10B pks⁺ and derivatives and quantification of H2AX phosphorylation. When indicated, spermidine (μg/ml) was added to the interaction medium during infection. MOI = 400. NI, noninfected. Data were combined from three independent experiments. ***, P < 0.001, and *, P < 0.05, by 1-way ANOVA. All bar graphs show mean values ± SEM. NS, not significant.