FIG 5 .

TPI is the only triosephosphate isomerase in M. tuberculosis. (A) Intrabacterial pool sizes and isotopic labeling of triose phosphates and hexose phosphate in the indicated M. tuberculosis strains after a 24-h incubation on media containing [U-¹³C]glycerol and acetate or glycerol and [U-¹³C]acetate. Total bar heights indicate the intrabacterial concentration, whereas the colored area of each bar denotes the extent of ¹³C labeling achieved from [U-¹³C]glycerol (purple) or [U-¹³C]acetate (blue). All values are averages ± SD from independent triplicate cultures. *, P < 0.05 Student’s t test. Data are representative of two independent experiments. (B) Schematic representation of the predicted isotopomeric distribution of ¹³C-labeled hexose phosphate and ¹³C-labeled triose phosphate in the WT and Δtpi strains after growth on [U-¹³C]glycerol- and acetate-containing media. ¹³C-labeled carbons are in pink. (C) Isotopomeric profile of triose phosphate and hexose phosphate of the samples used for panel A. m+0, unlabeled; m+1, singly ¹³C labeled; m+2, doubly ¹³C labeled, and so on. Differences in abundance between the m+6 isotopomer and all other isotopomers in WT were statistically significant (P < 0.05) except for the difference in abundance between the m+6 and m+0 isotopomers (P = 0.06). Differences in abundance of the m+3 isotopomer and all other detectable isotopomers in the Δtpi strain were statistically significant (P < 0.0001).