Activating Compound | Comment | Organism | Structure |
---|---|---|---|
fumarate | Arabidopsis NAD-ME1 is strongly stimulated by fumarate. Fumarate binding turns NAD-ME1 into a hyperbolic and high substrate affinity enzyme. This effect is also observed when the allosteric site is either removed or altered. Hence, fumarate is not really an activator, but suppresses the inhibitory effect of L-malate. Binding of L-malate and fumarate at the same allosteric site | Arabidopsis thaliana | |
fumarate | Arabidopsis NAD-ME1 is strongly stimulated by fumarate. Fumarate binding turns NAD-ME1 into a hyperbolic and high substrate affinity enzyme. This effect is also observed when the allosteric site is either removed or altered. Hence, fumarate is not really an activator, but suppresses the inhibitory effect of L-malate. Binding of L-malate and fumarate at the same allosteric site. Arg84 is essential for fumarate activation | Arabidopsis thaliana |
Cloned (Comment) | Organism |
---|---|
recombinant expression of His-tagged wild-type and mutant enzymes in Escherichia coli strain BL21(DE3) | Arabidopsis thaliana |
Protein Variants | Comment | Organism |
---|---|---|
additional information | mutants and chimeric proteins of NAD-ME1 and -2 indicated that the amino-terminal region of NAD-ME1 is implicated in fumarate activation and sigmoidal L-malate responses, structure-function analysis, overview. Generation of chimeric protein NAD-ME1q, which is composed of the first 176 amino acid residues of isozyme NAD-ME2 and the central and C-terminal sequence of isozyme NAD-ME1, exhibits a significantly lower Km L-malate value than the parental isoforms and a hyperbolic behavior that is not modified by fumarate | Arabidopsis thaliana |
additional information | mutants and chimeric proteins of NAD-ME1 and -2 indicated that the amino-terminal region of NAD-ME1 is implicated in fumarate activation and sigmoidal L-malate responses, structure-function analysis, overview. Generation of the chimeric protein NAD-ME2q, that possesses the first 176 amino acid residues of NAD-ME1 and the central and C-terminal sequence of NAD-ME2, presents a sigmoidal L-malate response similar to the one for NAD-ME1, but also a higher Km L-malate value and a lower kcat value. NAD-ME2q is activated by fumarate and an increase in its concentration produces a decrease in Km and nH values. At 4 mM fumarate, the Lmalate saturation curve is hyperbolic (nH = 1.1) with an 8fold decrease in Km value. There are no significant changes in kcat value by addition of fumarate, which implies a 9fold increase in NAD-ME2q catalytic efficiency when compared to the enzyme in the absence of fumarate | Arabidopsis thaliana |
R50A | site-directed mutagenesis, the mutant does not show altered kinetics after addition of fumarate | Arabidopsis thaliana |
R80A | site-directed mutagenesis, the mutant shows altered kinetics after addition of fumarate | Arabidopsis thaliana |
R84A | site-directed mutagenesis, the mutant does not show altered kinetics after addition of fumarate | Arabidopsis thaliana |
KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
additional information | - |
additional information | Arabidopsis NAD-ME1 exhibits a non-hyperbolic behavior for the substrate L-malate and presents a sigmoidal kinetic response for L-malate. Fumarate binding turns NAD-ME1 into a hyperbolic and high substrate affinity enzyme, overview | Arabidopsis thaliana | |
additional information | - |
additional information | NAD-ME2 shows a typical hyperbolic behavior | Arabidopsis thaliana |
Localization | Comment | Organism | GeneOntology No. | Textmining |
---|---|---|---|---|
mitochondrion | - |
Arabidopsis thaliana | 5739 | - |
Metals/Ions | Comment | Organism | Structure |
---|---|---|---|
Mg2+ | a divalent metal ion, Mn+2 or Mg+2+, is essential for the enzyme reaction | Arabidopsis thaliana | |
Mn2+ | a divalent metal ion, Mn+2 or Mg+2+, is essential for the enzyme reaction | Arabidopsis thaliana |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
(S)-malate + NAD+ | Arabidopsis thaliana | - |
pyruvate + CO2 + NADH | - |
r |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Arabidopsis thaliana | Q8L7K9 | - |
- |
Arabidopsis thaliana | Q9SIU0 | - |
- |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
(S)-malate + NAD+ | - |
Arabidopsis thaliana | pyruvate + CO2 + NADH | - |
r | |
additional information | NAD-ME1 has a regulatory site for L-malate that can also bind fumarate | Arabidopsis thaliana | ? | - |
? | |
additional information | NAD-ME1 has a regulatory site for L-malate that can also bind fumarate. L-Malate binding to this site elicits a sigmoidal and low substrate-affinity response, whereas fumarate binding turns NAD-ME1 into a hyperbolic and high substrate affinity enzyme. This effect is also observed when the allosteric site is either removed or altered. Fumarate is not really an activator, but suppresses the inhibitory effect of L-malate. Residues Arg50, Arg80 and Arg84 show different roles in organic acid binding. These residues form a triad, which is the basis of the homo and heterotrophic effects that characterize NAD-ME1 | Arabidopsis thaliana | ? | - |
? |
Synonyms | Comment | Organism |
---|---|---|
AT2g13560 | - |
Arabidopsis thaliana |
At4g00570 | - |
Arabidopsis thaliana |
NAD-dependent malic enzyme 1 | - |
Arabidopsis thaliana |
NAD-dependent malic enzyme 2 | - |
Arabidopsis thaliana |
NAD-ME1 | - |
Arabidopsis thaliana |
NAD-ME2 | - |
Arabidopsis thaliana |
Cofactor | Comment | Organism | Structure |
---|---|---|---|
NAD+ | - |
Arabidopsis thaliana | |
NADH | - |
Arabidopsis thaliana |
General Information | Comment | Organism |
---|---|---|
additional information | mutants and chimeric proteins of NAD-ME1 and -2 indicated that the amino-terminal region of NAD-ME1 is implicated in fumarate activation and sigmoidal L-malate responses, structure-function analysis, overview | Arabidopsis thaliana |
additional information | residues Arg50, Arg80 and Arg84 show different roles in organic acid binding. These residues form a triad, which is the basis of the homo and heterotrophic effects that characterize NAD-ME1. Mutants and chimeric proteins of NAD-ME1 and -2 indicated that the amino-terminal region of NAD-ME1 is implicated in fumarate activation and sigmoidal L-malate responses, structure-function analysis, overview | Arabidopsis thaliana |
physiological function | plant mitochondria can use L-malate and fumarate, which accumulate in large levels, as respiratory substrates. In part, this property is due to the presence of NAD-dependent malic enzymes (NAD-ME). Malic enzyme tracers reveal hypoxia-induced switch in adipocyte NADPH pathway usage | Arabidopsis thaliana |
physiological function | Plant mitochondria can use L-malate and fumarate, which accumulate in large levels, as respiratory substrates. In part, this property is due to the presence of NAD-dependent malic enzymes (NAD-ME). Malic enzyme tracers reveal hypoxia-induced switch in adipocyte NADPH pathway usage. Important role of NAD-ME1 in processes that control flow of C4 organic acids in Arabidopsis mitochondrial metabolism.. NAD-ME1 exhibits a complex homo and heterotrophic allosteric regulation with L-malate wielding an inhibitory effect that is cancelled by competitive fumarate binding | Arabidopsis thaliana |