Figure 4.

SBP and OBP are synthesized in vivo by C₃ + C₄ and C₃ + C₅ subunits via fructose bisphosphate aldolase.

(A) Cells were switched from unlabeled to 70:30 unlabeled glucose:[U-¹³C]-glucose. Labeling patterns of erythrose-4-phosphate (E4P), dihydroxyacetone-phosphate (DHAP), ribose-5-phosphate (R5P), SBP and OBP were measured in shb17Δ, where SBP and OBP accumulate and hence are more readily quantitated. The reaction products sedoheptulose-7-phosphate (S7P) and octulose 8-phosphate (O8P) were measured in wild type (for data on S7P in shb17Δ see Supplementary Figure 4A). Labeling is reported 20 minutes after nutrient switch for all compounds except OBP, where data is taken at 120 min due to its slower labeling.

(B) Kinetics of labeling of SBP after switching shb17Δ cells with wild type fructose bisphosphate aldolase (FBA1-wt), or the Decreased Abundance by mRNA Perturbation allele (FBA1-DAmP) into [U-¹³C₆]-glucose. For associated pool size and kinetic data, see Supplemental Figure 4 (B-C).

(C) Kinetics of labeling of SBP and S1P after switching shb17Δ cells into [U-¹³ C₆]-glucose.