Figure 5.

CtpC Is Involved in Zinc Detoxification and Contributes to the Intracellular Survival of M. tuberculosis

(A) Differential sensitivity of M. tuberculosis wild-type and the ctpC null mutant to free zinc. M. tuberculosis wild-type (GC1237), a ctpC null mutant (ctpC::Kan^R), or the cosmid-complemented strain (I437) was allowed to grow in 7H9-ADC medium containing 0.1 mM ZnSO₄ or without zinc supplementation (Control). Bacterial growth was monitored by turbidity measurement (McFarland units). The data are representative of three independent experiments.

(B) Differential sensitivity of M. tuberculosis wild-type and the ctpC null mutant to free zinc. M. tuberculosis wild-type (GC1237), a ctpC null mutant (ctpC::Kan^R), or the cosmid-complemented strain (I437) were allowed to grow in 7H9-ADC medium containing 0.5 mM ZnSO₄ or without zinc supplementation (Control). Bacterial growth was monitored by plating on agar and counting CFU. The data are representative of two independent experiments.

(C) Differential ability of M. tuberculosis wild-type and the ctpC null mutant to replicate in human macrophages. M. tuberculosis wild-type (GC1237), a ctpC null mutant (ctpC::Kan^R), or a plasmid-complemented strain (CP) was used to infect human macrophages at a multiplicity of infection of one mycobacteria per ten cells. After 4 hr, cells were washed and incubated in fresh medium for 5 days. The data shown are means ±SD of intracellular CFU counts in an experiment carried out in triplicate and analyzed with Student's t test. ^∗p < 0.05; NS, not significant. The data are representative of three independent experiments.