An iron-sulfur protein that requires a [4Fe-4S] cluster for activity . Quinolinate synthase catalyses the second step in the de novo biosynthesis of NAD+ from aspartate in some bacteria, with EC 1.4.3.16 (L-aspartate oxidase) catalysing the first step and EC 2.4.2.19 [nicotinate-nucleotide diphosphorylase (carboxylating)] the third step. In Escherichia coli, two of the residues that are involved in the [4Fe-4S] cluster binding appear to undergo reversible disulfide-bond formation that regulates the activity of the enzyme .
reaction mechanism with an early release of phosphate from dihydroxyacetone phosphate, that only, not glycerol 3-phosphate, can condense with iminoaspartate to form quinolinate. The NadA three-dimensional structure shows that there is no room in the active site to accommodate a condensation product on which the phosphate group from dihydroxyacetone phosphate is still present, overview. The enzyme has a triose phosphate isomerase activity catalyzing the reversible isomerization of glycerol 3-phosphate into dihydroxyacetone phosphate in an Fe/S-dependent manner
reaction mechanism with an early release of phosphate from dihydroxyacetone phosphate, that only, not glycerol 3-phosphate, can condense with iminoaspartate to form quinolinate. The NadA three-dimensional structure shows that there is no room in the active site to accommodate a condensation product on which the phosphate group from dihydroxyacetone phosphate is still present, overview. The enzyme has a triose phosphate isomerase activity catalyzing the reversible isomerization of glycerol 3-phosphate into dihydroxyacetone phosphate in an Fe/S-dependent manner
the presence of the Fe4S4 cluster generates an internal tunnel and a cavity to bind the substrate and and dehydrate it, which is initiated by the conserved residue Tyr21. Tyr21 is close to a conserved Thr-His-Glu. All of these residues are essential for activity and Tyr21 deprotonation, to form the reactive nucleophilic phenoxide anion, is mediated by the triad. NadA displays a dehydration mechanism significantly different from the one found in archetypical dehydratases such as aconitase, which use a serine residue deprotonated by an oxyanion hole
the presence of the Fe4S4 cluster generates an internal tunnel and a cavity to bind the substrate and and dehydrate it, which is initiated by the conserved residue Tyr21. Tyr21 is close to a conserved Thr-His-Glu. All of these residues are essential for activity and Tyr21 deprotonation, to form the reactive nucleophilic phenoxide anion, is mediated by the triad. NadA displays a dehydration mechanism significantly different from the one found in archetypical dehydratases such as aconitase, which use a serine residue deprotonated by an oxyanion hole
An iron-sulfur protein that requires a [4Fe-4S] cluster for activity [1]. Quinolinate synthase catalyses the second step in the de novo biosynthesis of NAD+ from aspartate in some bacteria, with EC 1.4.3.16 (L-aspartate oxidase) catalysing the first step and EC 2.4.2.19 [nicotinate-nucleotide diphosphorylase (carboxylating)] the third step. In Escherichia coli, two of the residues that are involved in the [4Fe-4S] cluster binding appear to undergo reversible disulfide-bond formation that regulates the activity of the enzyme [5].
the enzyme has a triose phosphate isomerase activity catalyzing the reversible isomerization of glycerol 3-phosphate into dihydroxyacetone phosphate in an Fe/S-dependent manner. Only dihydroxyacetone phosphate can then condense with iminoaspartate to form quinolinate. If glycerol 3-phosphate is not converted to dihydroxyacetone phosphate no quinolinate can be produced. The enzyme as triose phosphate isomerase is more efficient in the direction of dihydroxyacetone phosphate production
the enzyme has a triose phosphate isomerase activity catalyzing the reversible isomerization of glycerol 3-phosphate into dihydroxyacetone phosphate in an Fe/S-dependent manner. Only dihydroxyacetone phosphate can then condense with iminoaspartate to form quinolinate. If glycerol 3-phosphate is not converted to dihydroxyacetone phosphate no quinolinate can be produced. The enzyme as triose phosphate isomerase is more efficient in the direction of dihydroxyacetone phosphate production
protein contains 3-3.5 mol iron and 3-3.5 mol sulfur per mol. Majority of the iron is in the form of a [4Fe-4S]2+ cluster. The cluster is absolutely required for activity
NadA contains a [4Fe-4S] cluster cofactor with a unique, non-cysteinyl-ligated, iron ion (Fea), which binds the hydroxyl group of a postulated intermediate in the last step of the reaction to facilitate a dehydration. N1 and the C7 carboxylate group of quinolinate ligate to Fea in a bidentate fashion placing the C5 hydroxyl group of the postulated final intermediate distal to Fea and virtually incapable of coordinating to it
inhibitors 4-mercaptophthalic acid, 6-mercaptopyridine-2,3-dicarboxylic acid and 5-mercaptopyrazine-2,3-dicarboxylic acid bind to the catalytic iron site of the [4Fe-4S] cluster through their thiolate
an [4Fe-4S] cluster-containing enzyme. The Fe/S cluster of NadA (both Fe4S4 and Fe2S2) might play a significant structural role in NadA that could affect the triose phosphate isomerase activity
an [4Fe-4S] cluster-containing enzyme. The Fe/S cluster of NadA (both Fe4S4 and Fe2S2) might play a significant structural role in NadA that could affect the triose phosphate isomerase activity
structural analogue of the 5-hydroxy-4,5-dihydropyridine-2,3-dicarboxylic acid intermediate. Compound coordinates to the enzyme [4Fe-4S] cluster through a differentiated iron site, thus leading to the inhibition of quinolate formation. Compound is inhibitory in vitro and in vivo
the activity of the enzyme within Escherichia coli is diminished by exposure of the cells to 4.2 atm O2, while the activity in extracts is rapidly decreased by 0.2 atm O2. Inactivation in extracts can be gradually reversed during anaerobic incubation, but is blocked by alpha, alpha'-dipyridyl or by 1,10-phenanthroline
discontinuous enzymatic assay that couples the production of iminoaspartate by NadB with the condensation between DHAP and iminoaspartate to form quinolinic acid catalyzed by NadA. The assay is linear up to 0.25 mg of NadA, 10 microg of NadB is the lowest amount suitable to measure NadA activity, and under anaerobic conditions, NadA activity becomes independent of fumarate concentration, starting from 1 mM fumarate, but decreases at concentrations higher than 2 mM fumarate, due to inhibition of NadB by fumarate
three strictly conserved amino acids, Glu198, Tyr109, and Tyr23, are in close proximity to the bound product. Substitution of these amino acids with Gln, Phe, and Phe, respectively, leads to complete loss of activity
quinolinate synthase is a Fe4S4 cluster-containing dehydrating enzyme involved in the synthesis of quinolinic acid, the universal precursor of the essential nicotinamide adenine dinucleotide coenzyme
quinolinate synthase is an [4Fe-4S] cluster-containing dehydrating enzyme involved in synthesis of quinolinic acid, the universal precursor of the essential coenzyme nicotinamide adenine dinucleotide
quinolinate synthase is an [4Fe-4S] cluster-containing dehydrating enzyme involved in synthesis of quinolinic acid, the universal precursor of the essential coenzyme nicotinamide adenine dinucleotide
quinolinate synthase is a Fe4S4 cluster-containing dehydrating enzyme involved in the synthesis of quinolinic acid, the universal precursor of the essential nicotinamide adenine dinucleotide coenzyme
residues C291 and C294 of the C291XXC294XXC297 motif undergo reversible disulfide formation, which regulates the activity of the enzyme. Disulfide-bond formation and reduction are effected by oxidized and reduced forms of thioredoxin, with a midpoint potential of -264 mV for the redox couple
in presence of substrate analogue malate. Diffraction to 2.0 A resolution. Triangular architecture composed of a 3fold repeat of three-layer alphabetaalpha sandwich folding. The active site is located at the interface of the three domains and is centered on the pseudo-3fold axis. The malate molecule is tightly held near the bottom of the active site cavity
structures of NadA in complex with dihydroxyacetone phosphate, iminoaspartate analogues, and quinolinate. Dihydroxyacetone phosphate adopts a nearly planar conformation and chelates the [4Fe-4S] cluster via its keto and hydroxyl groups. The cluster may act as a Lewis acid in enediolate formation, like zinc in class II aldolases
mutant K219R/Y107F in complex with the first intermediate resulting from the condensation of dihydroxyacetone phosphate with iminoaspartate and the dihydroxyacetone phosphate analogue phosphoglycolohydroxamate, and mutant K219R/Y21F in complex with quinolinic acid. Phosphoglycolohydroxamate binds to NadA with its phosphate group at the site where the carboxylate groups of the first intermediate also bind
structures of complexes of the Y21F/K219R variant with 4-mercaptophthalic acid, 6-mercaptopyridine-2,3-dicarboxylic acid and 5-mercaptopyrazine-2,3-dicarboxylic acid, at 1.64 A, 1.9 A and 2.1 A resolution, respectively. The carboxylate groups of the inhibitors interact with active site amino acids of His19 and Ser36 (domain 1), Ser124 (domain 2) and His193 and Thr210 (domain 3), and all molecules bind to one iron of the cluster with their thiolate moiety
crystallization data. The mutated protein is unable to catalyze the aldo-keto isomerization and/or cyclization of the first intermediate resulting from the condensation of dihydroxyacetone phosphate with iminoaspartate that ultimately leads to quinolinic acid formation
crystallization data. The mutated protein is unable to catalyze the aldo-keto isomerization and/or cyclization of the first intermediate resulting from the condensation of dihydroxyacetone phosphate with iminoaspartate that ultimately leads to quinolinic acid formation
2.5.1.72 quinolinate synthase
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