FIG 3.

Analysis of amycobactin mutants in M. smegmatis and M. tuberculosis. (a) Alignment of protein sequences from WT M. smegmatis SecY and amycobactin mutants N28R1 and N28R2. The deletions in each mutant are boxed in red. (b) Growth curves of WT M. smegmatis and mutants containing targeted 3- and 6-amino-acid deletions in secY conferring resistance to amycobactin. (c) Growth curves of WT M. tuberculosis and a mutant containing a targeted 3-amino-acid deletion in secY conferring resistance to amycobactin. Data in panels b and c represent the results of two independent experiments and are displayed as means ± standard errors of the means. (d and e) Side view (d) and top view (e) of the predicted crystal structure of M. tuberculosis SecY, with the amycobactin resistance-conferring mutations shown in red. For reference, helices 2 and 7, which together form the lateral gate of SecY, are shown in blue. The plug restricting secretion through the central channel of SecY is shown in orange.