title: A differential redox regulation of the pathways metabolizing glyceraldehyde-3-phosphate tunes the production of reducing power in the cytosol of plant cells.
abstract: Adaptation to aerobic life leads organisms to sense reactive oxygen species and use the signal for coordination of the entire metabolism. Glycolysis in plants is a particular network 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 regulation to 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 oxidants than np-Ga3PDHase. Thioredoxin-h reverted the oxidation of both enzymes (although with differences between them), suggesting a physiological redox regulation. The results support a metabolic scenario where the cytosolic triose-phosphate dehydrogenases are regulated under changeable redox conditions. This would allow coordinate production of NADPH or ATP through glycolysis, with oxidative signals triggering reducing power synthesis in the cytosol. The NADPH increment would favor antioxidant responses to cope with the oxidative situation, while the thioredoxin system would positively feedback NADPH production by maintaining np-Ga3PDHase at its reduced active state.
authors.affiliation: Instituto de Agrobiotecnología del Litoral (IAL, CONICET-UNL), FBCB, Paraje "El Pozo", CC 242, Santa Fe S3000ZAA, Argentina. iglesias@fbcb.unl.edu.ar.
authors.forename: Claudia V
authors.initials: CV
authors.lastname: Piattoni
authors.forename: Sergio A
authors.initials: SA
authors.lastname: Guerrero
authors.forename: Alberto A
authors.initials: AA
authors.lastname: Iglesias
mesh_terms: D003600:Cytosol / Q000378:metabolism*; D005986:Glyceraldehyde 3-Phosphate / Q000378:metabolism*; D024601:Glyceraldehyde 3-Phosphate Dehydrogenase (NADP+) / Q000235:genetics / Q000378:metabolism*; D024581:Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating) / Q000235:genetics / Q000378:metabolism*; D006019:Glycolysis; D007700:Kinetics; D053858:Metabolic Networks and Pathways; D010084:Oxidation-Reduction; D059828:Plant Cells / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D014908:Triticum / Q000166:cytology / Q000235:genetics / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D011994:Recombinant Proteins; D005986:Glyceraldehyde 3-Phosphate; D024581:Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating); D024601:Glyceraldehyde 3-Phosphate Dehydrogenase (NADP+)