CEFOBI   05405
CENTRO DE ESTUDIOS FOTOSINTETICOS Y BIOQUIMICOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Study of the pyruvate carboxylase activity of NADP-maliz enzyme in C3 plants
Autor/es:
BADIA, MARIANA; ARIAS, C. L.; ANDREO, CS; MARIA FABIANA DRINCOVICH; MARIEL GERRARD WHEELER
Reunión:
Congreso; LI Reunión de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2015
Resumen:
NADP-malic enzyme (NADP-ME) catalyzes the reversible oxidative decarboxylation of malate to pyruvate, CO2 and NADPH. In A. thaliana, cytosolic NADP-ME2 is the isoform that mostly contributes to the forward NADP-ME activity. Studies with recombinant NADP-ME2 showed that it also has a high catalytic efficiency for the reverse reaction, i.e., the reductive carboxylation of pyruvate, and that this activity is differentially regulated by cell metabolites and pH. In this work, Arabidopsis mutant and overexpressing lines in NADP-ME2 were used to assess this possible anaplerotic reaction of NADP-ME. Total pyruvate carboxylation activity was measured in leaf extracts, being lower in plants lacking NADP-ME2 and higher in overexpressing lines, compared to wild type. In addition, the level of substrates and products of the reaction was analyzed. The plants overexpressing NADP-ME2 displayed higher malate and lower pyruvate content relative to wild type throughout day and night. Moreover, NADP/NADPH ratio was increased in these plants during the night. These results suggest that NADP-ME2 may be preferentially catalyzing the reverse over the forward reaction in the overexpressing lines. Thus, the pyruvate carboxylase activity of NADP-ME may take place in plant cells, contributing to the synthesis of C4 compounds and being regulated by cell metabolic status and environmental changes.