IAL   21557
INSTITUTO DE AGROBIOTECNOLOGIA DEL LITORAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Metabolism of triose-phosphate in wheat. Phosphorylation of cytosolic non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase
Autor/es:
ALBERTO A. IGLESIAS; CLAUDIA V. PIATTONI; GUERRERO, SERGIO A.
Lugar:
Minneapolis, Minnesota
Reunión:
Congreso; Annual Meeting of The American Society of Plant Biologists; 2011
Institución organizadora:
American Society of Plant Biologist
Resumen:
Non
phosphorylating glyceraldehyde-3-phosphate dehydrogenase (np-Ga3PDHase,
EC 1.2.1.9) is a glycolytic enzyme typical of the cytosol of plant
cells, mainly involved in deriving triose-P to produce NADPH. The enzyme
was found to be modified by phosphorylation in wheat heterotrophic
tissues. Phosphorylated np-Ga3PDHase interacts with 14-3-3 regulatory
proteins; afterward it turns less active and more sensitive to
regulation by adenylates and pyrophosphate. Herein we identify that the
Ser404 residue of wheat np-Ga3PDHase is specifically phosphorylated by
the SnRK (SNF1 related) protein kinase family. Interestingly, only the
kinase present in wheat heterotrophic tissues (endosperm), but not in
leaves, was found active. The specific SnRK was partially purified and
characterized as a ~200 kDa protein. The kinase also phosphorylated
SAMS, AMARA and SP46 peptides and it was recognized by antibodies rose
against a peptide conserved in SnRK1 from sorghum and maize developing
seeds. The kinase required Mg2+ or Mn2+ (but not Ca2+) for activity and
it was allosterically inhibited by physiological concentrations of
ribose-5P, and to a lesser extent by fructose-1,6-bisP and 3P-glycerate.
Glucose-6P (a main effector of spinach leaf SnRK1) produced little
effect. MALDI-TOF/TOF analysis evidenced that sucrose synthase
copurified with SnRK1, also being a target of phosphorylation. Results
support np-Ga3PDHase as a new target of SnRK1 action, identifying
distinctive allosteric regulation of SnRK1s present in photosynthetic or
non-green tissues. Phosphorylation of np-Ga3PDHase would be part of a
mechanism regulating carbon partitioning, determining triose-P usage to
produce NADPH or ATP in the cytosol of heterotrophic plant cells.