FIG 2 .
ppk2 is required for M. tuberculosis control of intracellular poly P levels and ATP/GTP ratio. (A) Intrabacillary poly P levels were measured in the wild-type, ppk2::Tn, and ppk2::Tn Comp strains during mid-log phase using a DAPI-based method and normalized to total protein content of extract lysate. Values that were significantly different (P < 0.05) are indicated by a bar and asterisk. Values are means ± standard deviations (error bars) for three biological replicate samples. (B) qRT-PCR analysis of gene expression of ppk2::Tn mutant and ppk2::Tn Comp strain compared to that of the wild type during late log phase of growth in supplemented Middlebrook 7H9 broth, expressed as a change in the normalized cycle threshold (−∆CT). (C) Intrabacillary ATP/GTP ratio of the wild-type, ppk2::Tn, and ppk2::Tn Comp strains during late log phase, as measured by HPLC. The values for ppk2::Tn and ppk2::Tn Comp strains were significantly different (P < 0.05) as indicated by the bar and asterisk. The values for the ppk2::Tn mutant and the wild-type strain were not significantly different (P = 0.07). Three biological replicate samples were used for each strain in each experiment.