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

LARA, MARIA V.; MÜLLER, GABRIELA L.; MAURINO, VERÓNICA G.; SAIGO, MARIANA; BOLOGNA, FEDERICO P.; CASATI, PAULA; ANDREO, CARLOS S.; DRINCOVICH, MARÍA F.; LARA, MARÍA VALERIA

Montreal

Congreso; 13th International Congress of Photosynthesis.; 2004

NADP-ME is a widely distributed enzyme implicated in diverse metabolic pathways. Plastidic and cytosolic NADP-ME isoforms were found in C3, C4 and CAM plants (Edwards & Andreo 1992, Drincovich et al 2001). At least three different batches of antibodies against purified NADP-ME from maize leaves (Maurino et al 1996, Tausta et al 2002) and Mesembryanthemun crystallinum (Honda et al 2000) detect a 72KDa protein, suggested to be a non-photosynthetic NADP-ME. This isoform was found, among others, in maize (Maurino et al 1996, 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 72KDa apparent molecular mass, 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 al 2003) and Ricinus communis cotyledons (Colombo et al 1998). However, the cDNA supposed to encode for this 72KDa NADP-ME in maize roots, codifies in fact for a novel highly active 66KDa NADP-ME (Saigo et al 2004). In addition, a sequence codifying for such 72-kDa NADP-ME has not been found neither among the cDNA known to codify for NADP-MEs nor in the arabidopsis genome. Evidence concerning the identity of the 72KDa protein purified as NADP-ME from maize and detected by antibodies against the purified NADP-ME from leaves is presented. This 72KDa protein may be in fact a Heat Shock Protein (Hsp70) associated to NADP-ME.