Fig. 7.

Effect of exogenous glucose on the P cycle and the TCA cycle in E. coli. (A) Percent survival of the indicated strains. Cells were grown in LB medium and then incubated in M9 medium plus acetate (10 mM) in the presence or absence of glucose (10 mM) or fructose (2.5 mM) plus gentamicin (1.2 μg/mL). (B) As in A showing intracellular PMF (Left) and NAD⁺/NADH (Right). (C) Relative expression of pck and maeA and maeB determined by qRT-PCR in Δpck or control cells. Cells were grown in LB medium and then incubated in M9 medium plus acetate (10 mM) in the presence or absence of glucose (6 mM). (D) Intracellular pyruvate determined by UPLC-MS in Δpck or control cells. Cells were grown in LB medium and then incubated in M9 medium plus acetate (10 mM) in the presence of 0, 2, 4, or 6 mM glucose, as indicated. (E and F) Relative expression of maeA, maeB, and pck determined by qRT-PCR (E) and intracellular pyruvate determined by UPLC-MS (F) in E. coli K12. Cells were grown in LB medium and then incubated in M9 medium plus acetate (10 mM) in the presence of the indicated concentrations of glucose. (G) Mass isotopomer distributions in E. coli. Cells were grown in LB medium and then incubated in M9 medium plus acetate (10 mM) in the presence or absence of ¹³C-labeled glucose (5 mM) and unlabeled glucose (5 mM). Black, ¹³C-labeled metabolites; gray, undetected metabolites. (H) Scatterplot of the abundance of the indicated metabolites in Δpck, ∆aceE, and ∆gltA E. coli. Cells were grown in LB medium and then incubated in M9 medium plus acetate (10 mM) in the presence or absence of glucose (10 mM). Results (A–E and H) are mean ± SEM of three biological repeats. Statistically significant values are indicated with an asterisk (*P < 0.05, **P < 0.01) and were determined by Student’s t test. P < 0.01 in gradient of D–F.