Figure 5. P. berghei parasites lacking the BCKDH-E1a subunit exhibit a perturbed TCA cycle.

Cultures containing ring/early-trophozoite WT and Pbe1a_ko P. berghei-infected RBCs were allowed to mature to schizonts and labelled with ¹³C-U-glucose or ¹³C-U-glutamine for 5 hr. Label incorporation was assessed by GC-MS. (A) Total ¹³C-glucose-derived label incorporation into central carbon metabolism metabolites in WT (blue) and Pbe1a_ko (red) P. berghei-infected RBCs, where label incorporation is the fraction of molecules of that metabolite containing one or more ¹³C carbons (after correction for natural abundance). Metabolites are colour-coded by metabolic pathway; central carbon metabolism, green; TCA cycle and associated amino acids, orange; PPP, purple; other, black. Error bars represent standard deviation (N = 4). Significance as determined by t-test is shown (corrected for multiple comparisons using the Holm-Sidak method), with significant (p-value<0.05) differences indicated by an asterisk. † indicates metabolite not detected. (B) Mass isotopologue distributions of the TCA intermediates shown in Panel A. The x-axis indicates the number of ¹³C-atoms in each metabolite (‘M’ indicates the monoisotopic mass containing no ¹³C atoms). The y-axis indicates fractional abundance of each isotopologue when labelled with ¹³C-U-glucose (present in the culture medium at ∼50%). Error bars indicate standard deviation (N = 4). (C, D) As for A and B, but after labelling with ¹³C-U-glutamine (present in the culture medium at ∼98%).