IAL   21557
INSTITUTO DE AGROBIOTECNOLOGIA DEL LITORAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Regulation of wheat cytosolic glyceraldehyde-3-phosphate dehydrogenase by redox mechanisms
Autor/es:
CLAUDIA V. PIATTONI; ALBERTO A. IGLESIAS; SERGIO A. GUERRERO
Lugar:
Minneapolis, Minnesota
Reunión:
Congreso; Annual Meeting of The American Society of Plant Biologists; 2011
Institución organizadora:
American Society of Plant Biologist
Resumen:
Plant
glycolysis is a particular complex network where specific steps seem
critical for regulation. The conversion of glyceraldehyde-3-phosphate
(Ga3P) into 3-phosphoglycerate (3-PGA) is one key point of this
metabolic pathway catalyzed by two different enzymes in plant cells
cytosol. Regulation of this critical step in determining triose-P fate
is far to be satisfactorily understood. We studied posttranslational
modifications operating on the two plant cytosolic Ga3P dehydrogenases:
the phosphorylating enzyme (p-Ga3PDHase, EC 1.2.1.12) [that together
with 3-PGA kinase derives triose-P to the synthesis of ATP and NADH],
and the non-phosphorylating enzyme (np-Ga3PDHase; EC 1.2.1.9) [that
leads triose-P to produce NADPH]. Both enzymes were found targets of
redox modification by reactive oxygen and nitrogen species (ROS and RNS,
respectively), being p-Ga3PDHase markedly more sensitive to thiol
oxidants than np-Ga3PDHase. Thus, p-Ga3PDHase was oxidized by H2O2 with a k" of 119 M-1 s-1,
which is 63-fold higher than that obtained for np-Ga3PDHase oxidation.
Loss of activity of both enzymes was deferentially but effectively
reversed by reduced thioredoxin-h (TRX-h), suggesting that the process
could function physiologically. Results support a rerouting of cytosolic
triose-P toward synthesis of NADPH instead of ATP under oxidative cell
conditions, which would favor antioxidant systems coping with oxidative
stress. Furthermore, TRX-h would positively feedback NADPH production
via np-Ga3PDHase by maintaining the enzyme at a reduced (more active)
state