Specific Arabidopsis thaliana malic enzyme isoforms can provide anaplerotic pyruvate carboxylation function in Saccharomyces cerevisiae

MARIANA B. BADIA; ROBERT MANS; ALICIA V. LIS; MARCOS A TRONCONI; CINTIA L. ARIAS; VERONICA G. MAURINO; CARLOS S. ANDREO; MARIA F.DRINCOVICH; ANTONIUS J. A. VAN MARIS; MARIEL GERRARD WHEELER

FEBS JOURNAL

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2017

1742-464X

NAD(P)-malic enzyme (NAD(P)-ME) catalyzes the reversible oxidativedecarboxylation of malate to pyruvate, CO2, and NAD(P)H and is presentas a multigene family in Arabidopsis thaliana. The carboxylation reactioncatalyzed by purified recombinant Arabidopsis NADP-ME proteins is fasterthan those reported for other animal or plant isoforms. In contrast, no carboxylationactivity could be detected in vitro for the NAD-dependent counterparts.In order to further investigate their putative carboxylating rolein vivo, Arabidopsis NAD(P)-ME isoforms, as well as the NADP-ME2del2(with a decreased ability to carboxylate pyruvate) and NADP-ME2R115A(lacking fumarate activation) versions, were functionally expressed in thecytosol of pyruvate carboxylase-negative (Pyc) Saccharomyces cerevisiaestrains. The heterologous expression of NADP-ME1, NADP-ME2 (and itsmutant proteins), and NADP-ME3 restored the growth of PycS. cerevisiaeon glucose, and this capacity was dependent on the availability ofCO2. On the other hand, NADP-ME4, NAD-ME1, and NAD-ME2 couldnot rescue the Pycstrains from C4 auxotrophy. NADP-ME carboxylationactivity could be measured in leaf crude extracts of knockout and overexpressingArabidopsis lines with modified levels of NADP-ME, where thisactivity was correlated with the amount of NADP-ME2 transcript. Theseresults indicate that specific A. thaliana NADP-ME isoforms are able toplay an anaplerotic role in vivo and provide a basis for the study on thecarboxylating activity of NADP-ME, which may contribute to the synthesisof C4 compounds and redox shuttling in plant cells.