IAL   21557
INSTITUTO DE AGROBIOTECNOLOGIA DEL LITORAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
CONCERNING THE PHOSPHORYLATION OF THE CLASSIC GLYCOLYTIC GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE IN PLANTS
Autor/es:
PIATTONI, CLAUDIA V.; GUERRERO, SERGIO A.; IGLESIAS, ALBERTO A.
Lugar:
Mar del Plata, Buenos Aires, Argentina
Reunión:
Congreso; XXIX Reunión Argentina de Fisiología Vegetal; 2012
Institución organizadora:
Sociedad Argentina de Fisiología Vegetal
Resumen:
In a previous report we showed that in wheat (Triticum aestivum) heterotrophic tissues, non phosphorylating glyceraldehyde 3 phosphate dehydrogenase (np-Ga3PDHase, EC 1.2.1.9) is phosphorylated at Ser-404 by a SnRK1 (SNF1 related) protein kinase. Phosphorylated np Ga3PDHase interacts with 14 3 3 regulatory proteins; afterward the enzyme exhibits lower activity and enhanced sensitivity to regulation by adenylates and inorganic pyrophosphate. Further studies on regulation of SnRK1 from wheat heterotrophic tissues, showed that nearly physiological concentrations of Rib5P and, to a lesser extent, Fru1,6bisP and 3PGA, inhibited the kinase activity. Surprisingly, Glc6P (the main effector of spinach leaf SnRK1) produced little or no effect. In this work, we show that classic cytosolic phosphorylating glyceraldehyde-3-phosphate dehydrogenase (Ga3PDHase, EC 1.2.1.12) is also a target for phosphorylation in wheat. By analyzing the recombinant and source enzyme we found that phosphorylation occurs in heterotrophic tissues under physiological conditions. Working with recombinant Ga3PDHase we found that phosphorylation occurs at the Ser-205 residue. Mutation of Ser-205 to Ala abolished this post-translational modification. Furthermore, in vitro phosphorylation of Ga3PDHase is likewise catalyzed by SnRK1 protein kinase also inhibited by Rib5P; notwithstanding phosphorylation by other kinases cannot be discarded. Phosphorylation caused a significant decrease in the Ga3PDHase activity but no substantial change in the enzyme affinity toward substrates. The mutant S205D, mimicking the phosphorylated form of the enzyme, was found inactive. Results suggest that activity of Ga3PDHase could by controlled by phosphorylation in developing heterotrophic wheat tissues. In a wider scenario, posttranslational modification by SnRK1 would be critical to modulate the use of triose-P to produce ATP or NADPH in the cytosol of non-photosynthetic tissues.