Fig. 6.

PrrAB regulates cytochrome bd and dosR expression and is protective during hypoxia and cyanide-mediated respiratory inhibition. qRT-PCR of (a) cydA (MSMEG 3233), (b) cydB (MSMEG 3232), (c) cydD (MSMEG 3231), (d) dosR1 (MSMEG 5244), and (e) dosR2 (MSMEG 3944) RNA isolated from M. smegmatis strains cultured under aerobic (solid bars) or hypoxic (hatched bars) conditions for 24 h. Relative gene expression was calculated using the 2^-ΔCt method and normalized to 16S rRNA for each strain and growth condition. qRT-PCR measurements for each gene and each condition (aerobic or hypoxic growth) was assessed in triplicate. *, p < 0.05; **, p < 0.01; ***, p < 0.001; one-way ANOVA, Dunnett’s multiple comparisons. (f) M. smegmatis growth in the presence (dashed lines) or absence (solid lines) of 1 mM cyanide (KCN). **, p < 0.01; ****, p < 0.0001; unpaired Student’s t tests. Values represent the mean ± SEM of data collected from three independent cultures