Figure 5.

The PYK-PEP-TPI Feedback Loop Stabilizes ROS Levels by Activating the Pentose Phosphate Pathway

(A) Overview on the PPP and glycolysis.

(B) Cells with low PYK activity have increased concentrations of PPP intermediates. Sugar phosphates were extracted from exponential cultures and quantified by LC-MRM. All measured PPP intermediates—g6p (glucose 6-phosphate), f6p (fructose 6-phosphate), 6pg (6-phosphogluconate), r5p (ribose 5-phosphate), rib5p (ribulose 5-phosphate), x5p (xylulose 5-phosphate), s7p (sedoheptulose 7-phosphate), and e4p (erythrose 4-phosphate)—as well as TPI substrates dhap (dihydroxyacetone phosphate) and gly3p (glyceraldehyde 3-phosphate) were increased in yeast with low PYK activity grown in glucose (upper panel) and galactose media (lower panel). Reproducibility of sugar phosphate quantification is demonstrated by linear regression (R² 0.989) (lower panel left). See also Table S1.