CHARACTERIZATION OF NADP DEPENDENT MALIC ENZYME FROM FLAVERIA SPECIES

SAAVEDRA DAMIAN DARÍO; AMERISO MARÍA CARMEN; DRINCOVICH MARÍA FABIANA; ANDREO CARLOS SANTIAGO

San Miguel de Tucumán

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

CHARACTERIZATION OF NADP DEPENDENT MALIC ENZYME FROMFLAVERIA SPECIESSaavedra, D. D.; Ameriso, M. C.; Drincovich, M. F. and Andreo, C. S.CEFOBI - Fac. Cs. Bioq. y Farm. UNR. Rosario. Argentina. e-mail: saavedra@cefobiconicet.gov.arNADP-malic enzyme (NADP-ME) is a widely distributed protein involved in differentmetabolic pathways. In the most common C4 pathway for carbon fixation, thedecarboxylation of malate is carried out by a NADP-ME. To understand the molecularevents underlying the evolution of C4 photosynthesis, we have studied NADP-ME inFlaveria genus, which include C4, C3 and C3-4 intermediates species. Isoforms ofplastidic NADP-ME are encoded by two genes in all species of Flaveria. Phylogeneticrelationships placed these isoenzymes in two separates groups, called photosyntheticand no photosynthetic isoforms. We analyzed, by RT-PCR, the expression of thesegenes in developing leaves of the intermediate species F. palmeri and F. sonorensisfinding out both genes are expressed in almost all the developmental stages tested. Tocompare the expression pattern we are setting up a quantitative protocol based on a Realtime-PCR method. At the moment, the analysis showed a developmental and speciedependent expression of these genes. On the other hand, recombinant isoforms ofNADP-ME from C4 F. trinervia and C3-C4 F. palmeri were purified and characterized.These enzymes showed different kinetics properties such as malate inhibition orsubstrates Kms, in spite of the high degree of sequence identity (more than 90%).Different expression levels and kinetic parameters suggest distinct function for twoisoforms.