Characterization of NADP dependent malic enzyme from Flaveria species

D SAAVEDRA; CARMEN AMERISO; MARIA FABIANA DRINCOVICH; ANDREO, CARLOS S

Tucumán

Congreso; XLV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2009

SAIB

NADP-malic enzyme is a widely distributed protein involved in different metabolic pathways. In the most common C4 pathway for carbon fixation, the decarboxylation of malate is carried out by a NADP-ME. To understand the molecular events underlying the evolution of C4 photosynthesis, we have studied NADP-ME in Flaveria genus, which include C4, C3 and C3-4 intermediates species. Isoforms of plastidic NADP-ME are encoded by two genes in all species of Flaveria. Phylogenetic relationships placed these isoenzymes in two separates groups, called photosynthetic and no photosynthetic isoforms. We analyzed, by RT-PCR, the expression of these genes in developing leaves of the intermediate species F. palmeri and F. sonorensis finding out both genes are expressed in almost all the developmental stages tested. To compare the expression pattern we are setting up a quantitative protocol based on a Real time-PCR method. At the moment, the analysis showed a developmental and specie dependent expression of these genes. On the other hand, recombinant isoforms of NADP-ME from C4 F. trinervia and C3-C4 F. palmeri were purified and characterized. These enzymes showed different kinetics properties such as malate inhibition or substrates Kms, in spite of the high degree of sequence identity (more than 90%). Different expression levels and kinetic parameters suggest distinct function for two isoforms