INVESTIGADORES
IGLESIAS Alberto Alvaro
congresos y reuniones científicas
Título:
Understanding the Partitioning of Trioses-phosphate; a Link Between the Metabolism of Carbon, Energy and Reducing Equivalents in the Cytosol of Plant Cells
Autor/es:
A.A. IGLESIAS, C.V. PIATTONI, S.A. GUERRERO
Lugar:
Mérida, Yucatán, México
Reunión:
Congreso; Joint Meeting of the American Society of Plant Biologists and the Sociedad Mexicana de Bioquímica; 2008
Institución organizadora:
Aerican Society of Plant Biologists
Resumen:
Abs # P21002: Understanding the partitioning of trioses-phosphate; a link between the metabolism of carbon, energy and reducing equivalents in the cytosol of plant cells Presenter: Iglesias, Alberto A       Contact Presenter Authors Iglesias, Alberto A (A)   Piattoni, Claudia V (A)   Guerrero, Sergio A (A)   Affiliations: (A): Lab. Enzimologia Molecular. Fac. Bioquimica Cs. Biologicas. Universidad Nacional del Litoral Non-phosphorylating glyceraldehyde-3P dehydrogenase (npGa3PDHase; EC 1.2.1.9) is a cytosolic enzyme found in photosynthetic eukaryotes. In green cells the enzyme is involved in a shuttle system to export chloroplastic NADPH. In non-green tissues, the role of the enzyme is less clear; although it catalyzes a critical metabolic branch point in glycolysis, where trioses-P are derived to produce NADPH as an alternative to the synthesis of ATP and NADH. We characterized the post-translational regulation of wheat npGa3PDHase by two mechanisms: phosphorylation of serine residues and redox modification of cysteines. The recombinant enzyme was phosphorylated after incubation with wheat endosperm extracts, under reaction conditions specific for SNF1-related protein kinases. The modification was inhibited by glucose-6P. Phosphorylation was neither observed by other plant protein kinases, nor by incubation with leaf extracts. Site directed mutagenesis studies showed that Ser-404 is the amino acid residue phosphorylated in npGa3PDHase. These results agree with previous data showing that in heterotrophic plant cells the enzyme exhibits distinctive regulatory properties associated with phosphorylation and interaction with 14-3-3 proteins. On the other hand, npGa3PDHase from wheat was inactivated by thiol oxidants as diamide, and hydrogen peroxide. The loss of activity was effectively reversed after incubation with dithiothreitol and reduced thioredoxin, thus suggesting that the process could function physiologically. Results support a scenario where the oxidation of trioses-P is a key metabolic point to regulate the carbon partitioning to produce redox or energy equivalents in the cytosol of plant cells. Work granted by CONICET, ANPCyT and UNL (Argentina).