Differential fumarate binding to Arabidopsis NAD+-malic enzymes 1 and -2 produces an opposite activity modulation

► NAD-ME activity in Arabidopsis is modulated in concert by fumarate and NAD+. ► Fumarate is an active site-associated inhibitor of NAD-ME2. ► NAD-ME1 presents an allosteric site that regulates the fumarate activation. ► Mutagenesis, urea denaturation and intrinsic fluorescence quenching assays were used.