FIG 4.

Iron and zinc inhibit secretion of M. tuberculosis EsxG-EsxH. (A to D) M. tuberculosis was grown in C.S. containing iron (FeCl₃) or zinc (ZnSO₄) as indicated. (A and C) EsxG-EsxH and Ag85 complex proteins were analyzed by Western blotting of cell lysates and CFs after 3-day (A) and 6-day (C) treatments. Long exposures of the CF are shown to demonstrate the presence of EsxG-EsxH in media containing both iron and zinc. (B and D) EsxG-EsxH protein levels in CF were quantified from three independent experiments using ImageJ software and normalized to Ag85. Data represent the means ± the SEM. *, P < 0.05; **, P < 0.01 (unpaired Student t test). n.s., not significant.