A high-frequency single nucleotide polymorphism in the MtrB sensor kinase in clinical strains of Mycobacterium tuberculosis alters its biochemical and physiological properties
Fig 5
Analysis of growth rates and cell size of strains overexpressing wild-type or mutant MtrB.
A. Growth curves of H37Ra strains overexpressing mtrB WT, mtrB’ (M517L) or the vector alone in 7H9 medium (containing 10% OADC, 0.5% glucose, 0.05% Tween80) (n = 3). B. Transmission electron microscopy analysis (TEM) of recombinant H37Ra strains. Representative micrographs of various strains as indicated. C. Normalized distribution of the bacterial cell length of various strains based on the EM images shown in Fig 5B. D. Average cell length of various strains calculated from EM images shown in Fig 5B. E. Representative topographical images of various strains (as indicated) by atomic force microscopy (AFM). The upper panel of images represent the peak force error maps for each sample and the lower panel of images show the height of each sample. F. Graph showing the nonlinear regression fit of the fluorescence curve obtained for the three strains vector control, mtrB WT and mtrB’ M517L at an excitation-emission of 530–590 obtained after incubation with EtBr (statistical analysis performed only for the last time point of 60min). G. Membrane permeability calculated by the accumulation of EtBr over 60 minutes and represented as t1/2 in seconds at a concentration of 0.5 μM of EtBr. The slopes of fluorescence emission curve obtained in Fig 5G were used to determine the t1/2 value for membrane permeability. For all experiments, n = 3. (P values; *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001, ****P ≤ 0.0001).