Studies concerning the identity of the so called 72 kDa NADP-malic enzyme

LARA, M. VALERIA; MÜLLER, GABRIELA L.; MAURINO, VERÓNICA G.; SAIGO, MARIANA; BOLOGNA, FEDERICO P.; CASATI PAULA,; ANDREO CARLOS S.; DRINCOVICH, MA. FABIANA

Montreal

Congreso; XIII International Congress of Photosynthesis; 2004

NADP-ME is a widely distributed enzyme implicated in diverse metabolic pathways. Plastidic andcytosolic NADP-ME isoforms were found in C3, C4 and CAM plants (Edwards and Andreo 1992, Drincovich etal 2001).At least three different batches of antibodies against purified NADP-ME from maize leaves (Maurino etal 1996, Tausta et al 2002) and Mesembryanthemun crystallinum (Honda et al 2000) detect a 72 kDa protein,suggested to be a non-photosynthetic NADP-ME. This isoform was found, among others, in maize (Maurino et al1996, 1997, Tausta et al 2002), various Flaveria species (Drincovich et al 1998), wheat (Maurino et al 1997,Casati et al 1997), and in Aloe arborescent (Honda et al 2000). NADP-ME with a 72 kDa apparent molecularmass, as assessed by Coomassie stained SDS-PAGE, was also purified from maize roots (Maurino et al 2001),wheat stems (Casati et al 1997), Egeria densa leaves (Casati et al 2000), Aptenia cordifolia leaves (Falcone et al2003) and Ricinus communis cotyledons (Colombo et al 1998). However, the cDNA supposed to encode for this72 kDa NADP-ME in maize roots, codifies in fact for a novel highly active 66 kDa NADP-ME (Saigo et al2004). In addition, a sequence codifying for such 72-kDa NADP-ME has not been found neither among thecDNA known to codify for NADP-MEs nor in the arabidopsis genome.Evidence concerning the identity of the 72 kDa protein purified as NADP-ME from maize and detected byantibodies against the purified NADP-ME from leaves is presented. This 72 kDa protein may be in fact a Heat ShockProtein (Hsp70) associated to NADP-ME.