A Differential Redox Regulation or the Pathways Metabolizing Glyceraldehyde-3-phosphate Tunes the Production of Reducing Power in the Cytosol of Plant Cells

C.V. PIATTONI; S.A. GUERRERO; A.A. IGLESIAS

INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES

MOLECULAR DIVERSITY PRESERVATION INTERNATIONAL-MDPI

Lugar: Basel; Año: 2013 vol. 14 p. 8073 - 8092

1422-0067

Adaptation to aerobic life leads organisms to sense reactive oxygen species anduse the signal for coordination of the entire metabolism. Glycolysis in plants is a particularnetwork where specific steps, like oxidation of glyceraldehydes-3-phosphate (Ga3P), are critical in order for it to function. The triose-phosphate can be converted into 3-phosphoglycerate through the phosphorylating Ga3P dehydrogenase (Ga3PDHase, EC 1.2.1.12) producing ATP and NADH, or via the non-phosphorylating enzyme (np-Ga3PDHase; EC 1.2.1.9) generating NADPH. In this work we found redox regulationto be a posttranslational mechanism allowing the fine-tuning of the triose-phosphate fate.Both enzymes were inactivated after oxidation by reactive oxygen and nitrogen species.Kinetic studies determined that Ga3PDHase is marked (63-fold) more sensitive to oxidantsthan np-Ga3PDHase. Thioredoxin-h reverted the oxidation of both enzymes (although withdifferences between them), suggesting a physiological redox regulation. The resultssupport a metabolic scenario where the cytosolic triose-phosphate dehydrogenases areregulated under changeable redox conditions. This would allow coordinate production ofNADPH or ATP through glycolysis, with oxidative signals triggering reducing powersynthesis in the cytosol. The NADPH increment would favor antioxidant responses to copewith the oxidative situation, while the thioredoxin system would positively feedbackNADPH production by maintaining np-Ga3PDHase at its reduced active state.