Quinolinate Phosphoribosyltransferase Activity Research Articles

Cell stress response impairs de novo NAD+ biosynthesis in the kidney.

The biosynthetic routes leading to de novo nicotinamide adenine dinucleotide (NAD+) production are involved in acute kidney injury (AKI), with a critical role for quinolinate phosphoribosyl transferase (QPRT), a bottleneck enzyme of de novo NAD+ biosynthesis. The molecular mechanisms determining reduced QPRT in AKI, and the role of impaired NAD+ biosynthesis in the progression to chronic kidney disease (CKD), are unknown. We demonstrate that a high urinary quinolinate-to-tryptophan ratio, an indirect indicator of impaired QPRT activity and reduced de novo NAD+ biosynthesis in the kidney, is a clinically applicable early marker of AKI after cardiac surgery and is predictive of progression to CKD in kidney transplant recipients. We also provide evidence that the endoplasmic reticulum (ER) stress response may impair de novo NAD+ biosynthesis by repressing QPRT transcription. In conclusion, NAD+ biosynthesis impairment is an early event in AKI embedded with the ER stress response, and persistent reduction of QPRT expression is associated with AKI to CKD progression. This finding may lead to identification of noninvasive metabolic biomarkers of kidney injury with prognostic and therapeutic implications.

Changes in trigonelline (N-methylnicotinic acid) content and nicotinic acid metabolism during germination of mungbean (Phaseolus aureus) seeds

Changes in trigonelline content and in biosynthetic activity were determined in the cotyledons and embryonic axes of etiolated mungbean (Phaseolus aureus) seedlings during germination. Accumulation of trigonelline (c. 240 nmol per pair of cotyledons) was observed in the cotyledons of dry seeds; trigonelline content decreased 2 d after imbibition. Trigonelline content in the embryonic axes increased with seedling growth and reached a peak (c. 380 nmol per embryonic axis) at day 5. Trigonelline content did not change significantly during the differentiation of hypocotyls, and the concentration was greatest in the apical 5 mm. Nicotinic acid and nicotinamide were better precursors for pyridine nucleotide synthesis than quinolinic acid, but no great differences were found in the synthesis of trigonelline from these three precursors. Trigonelline synthesis was always higher in embryonic axes than in cotyledons. Activity of quinolinate phosphoribosyltransferase (EC 2.4.2.19), nicotinate phosphoribosyltransferase (EC 2.4.2.11), and nicotinamidase (EC 3.5.1.19) was found in cotyledons and embryonic axes, but no nicotinamide phosphoribosyltransferase (EC 2.4.2.12) activity was detected. It follows that quinolinic acid and nicotinic acid were directly converted to nicotinic acid mononucleotide by the respective phosphoribosyltransferases, but nicotinamide appeared to be converted to nicotinic acid mononucleotide after conversion to nicotinic acid. Trigonelline synthase (nicotinate N-methyltransferase, EC 2.1.1.7) activity increased in the embryonic axes, but decreased in cotyledons during germination. [14C]Nicotinic acid and trigonelline absorbed by the cotyledons were transported to the embryonic axes during germination. Trigonelline had no effect on the growth of seedlings, but nicotinic acid and nicotinamide significantly inhibited the growth of roots. Based on these findings, the role of trigonelline synthesis in mungbean seedlings is discussed.

Influence of adenine-induced renal failure on tryptophan-niacin metabolism in rats.

To discover the role of the kidney in tryptophan degradation, especially tryptophan to niacin, rat kidneys were injured by feeding a diet containing a large amount of adenine. The kidney contains very high activity of aminocarboxymuconate-semialdehyde decarboxylase (ACMSD), which leads tryptophan into the glutaric acid pathway and then the TCA cycle, but not to the niacin pathway. On the other hand, kidneys contain significant activity of quinolinate phosphoribosyltransferase (QPRT), which leads tryptophan into the niacin pathway. The ACMSD activity in kidneys were significantly lower in the adenine group than in the control group, while the QPRT activity was almost the same, however, the formations of niacin and its compounds such as N1-methylnicotinamide and its pyridones did not increase, and therefore, the conversion ratio of tryptophan to niacin was lower in the adenine group than in the control group. The contents of NAD and NADP in liver, kidney, and blood were also lower in the adenine group. The decreased levels of niacin and the related compounds were consistent with the changes in the enzyme activities involved in the tryptophan-niacin metabolism in liver. It was concluded from these results that the conversion of tryptophan to niacin is due to only the liver enzymes and that the role of the kidney would be extremely low.

Peroxisome-Proliferator Regulates Key Enzymes of the Tryptophan-NAD+ Pathway

Structually diverse peroxisome-proliferators (PPs) were investigated regarding their effects on NAD+ level and two key enzyme activities in the tryptophan (Trp)–NAD+ pathway in the liver of rats (Sprague–Dawley male) fed PP-containing diets freely for 2 weeks. All PPs, except for thyroxine, significantly increased hepatic NAD+ level in concert with hepatic hypertrophy. Activity of quinolinate phosphoribosyltransferase (QAPRTase), one of the key enzymes in the Trp–NAD+ pathway, was increased by the PPs which caused significant increase in the hepatic NAD+. On the other hand, α-amino-β-carboxymuconate-ϵ-semialdehyde decarboxylase (ACMSDase), another key enzyme in the Trp–NAD+ pathway, was drastically inhibited by all PPs except for linolenic acid, which was only slightly inhibitory. Most PPs investigated activated peroxisomal marker enzymes such as palmitoyl-CoA oxidase, catalase, and PPAR-α(peroxisome-proliferator activated receptor-α)-dependent enzymes, such as malic enzyme and l-3-glycerophosphate dehydrogenase. NAD+ was also increased in the rat hepatocytes cultured in the medium supplemented with PPs. These data suggested that regulation of the key enzymes in the Trp–NAD+ pathway was associated with PPAR-α directly or indirectly, and as a consequence the hepatic NAD+ was increased by PPs.

Effects of peroxisome-proliferators on the TRP-NAD pathway.

The mechanism of the elevation of hepatic NAD level in the rats administered clofibrate and other peroxisome-proliferators were investigated. In the hepatocytes from the clofibrate-fed rats, NAD biosynthesis from Trp, but not from nicotinic acid, was specifically stimulated. The activities of peroxisomal marker enzymes, the peroxisome-proliferator activated receptors (PPAR)-dependent enzymes and key enzymes in the Trp-NAD pathway changed in parallel with the hepatic NAD increase; the activity of quinolinate phosphori-bosyltransferase (QPRT) was increased whereas that of alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD) was drastically reduced. The results strongly suggest that the hepatic NAD increase might be caused by transcription of genes coding the key enzymes of the Trp-NAD pathway via PPAR.

Abnormally high activity of 3-hydroxyanthranilate 3,4-dioxygenase in brain of epilepsy-prone El mice

Quinolinic acid (QUI), a structural analogue of neurotransmitters such as l-glutamate and l-aspartate, may act as an ‘excitotoxin’ when it is abundant in the brain. The compound has been causally related to various neurodegenerative disorders, including epilepsy 20. We tested the capacity of the brains of epilepsy-prone El mice to synthesize QUI. The activity of 3-hydroxyanthranilate 3,4-dioxygenase in the cerebral cortex of El mice was about 17 times that of ddY mice, the parent strain of El mice. The activity of this enzyme was undetectable in brains of BALB/cA mice and C3H/HeN mice. In El mice the sexes had comparable enzyme activity. The enzyme activity increased gradually as the animals aged. An injection of endotoxin caused a further increase in the enzyme activity. The enzyme activity in the spleen of El mice did not differ from the of ddY mice, and endotoxin did not affect the enzyme activity in the spleen. No strain-difference was observed in the activity of quinolinate phosphoribosyltransferase, a QUI-degrading enzyme, in the cerebral cortex. These results suggest that an increase in the synthesis of QUI in the brain is involved in the pathogenesis of epileptic seizures in El mice.

No Influence of an Injection of Paraquat and Exposure to Hyperoxia on Liver Quinolinate Phosphoribosyltransferase Activity in Rats.

No Influence of an Injection of Paraquat and Exposure to Hyperoxia on Liver Quinolinate Phosphoribosyltransferase Activity in Rats.

Influence of dietary change from a niacin- and protein-free diet to a niacin-free 30% casein diet on niacin formation from tryptophan in rats.

Niacin formation from tryptophan was compared in two groups of rats, one fed a niacin- and protein-free diet (group A) and the other, niacin-free 30% casein diet (group B) for one day after preliminary feeding of a niacin- and protein-free diet for three days (experiment I). In the other experiment, L-tryptophan was added to the last day's diets (experiment II). NAD and the total niacin contents in liver as well as urinary excretion of pyridine compounds were significantly higher in group I-B than in group I-A. L-Tryptophan supplementation reversed the total niacin content in liver, while total tryptophan intake was about two times higher in group II-B. Since the activities of kynurenine metabolizing enzymes had not changed, we considered that it was not due to a difference in kynurenine metabolism. Urinary excretion of quinolinic acid tended to be higher in group II-A than in group II-B. However, quinolinate phosphoribosyltransferase activity did not differ significantly. On the other hand, the activities of α-amino-β-carboxymuconate-ε-semialdehyde decarboxylase (ACMSDase) in both liver and kidneys were found to be significantly higher in group II-B than in group II-A. This might be responsible for the lower content of liver total niacin in group II-B.

Effect of L-tryptophan and L-leucine on biosynthesis of niacin-related compounds in Saccharomyces carlsbergensis.

As a model system for investigating the mechanism of the hepatic NAD-lowering effect of leucine in rats, aerobically grown Saccharomyces carlsbergensis was used in this paper. Tryptophan supplementation of the medium doubled total niacin production by S. carlsbergensis. This elevation in total niacin was mainly due to increases in niacin (14 times) and niacinamide nucleotides (2 times). Among nucleotides, the NAD level doubled whereas NADH, NADP and NADPH levels dropped significantly. Simultaneous supplementation of the medium with leucine suppressed the elevation in total and free niacin levels. In the presence of tryptophan, approximately 50% of the total niacin was secreted in the medium in the form of free niacin, while in the presence of both tryptophan and leucine most of the total niacin remained in the cell. The specific activity of quinolinate phosphoribosyltransferase [EC 2.4.2.19] was not affected by supplementation of the medium with tryptophan and/or leucine. In contrast, the specific activity of nicotinamide deamidase [EC 3.5.1.19] increased fivefold in the presence of tryptophan. Simultaneous supplementation of the medium with leucine tryptophan. Simultaneous supplementation of the medium with leucine suppressed the increase in nicotinamide deamidase. Cellular incorporation of tryptophan was not affected by leucine simultaneously added as a supplement to the medium. Leucine did not have any inhibitory effect on total niacin synthesis from 3-hydroxyanthranilate. From the results, a possible mechanism for the inhibitory effect of leucine on the tryptophan-NAD pathway was discussed.

The biosynthesis of nicotinamide adenine dinucleotide. XIII. Crystalline quinolinate phosphoribosyltransferase from Alcaligenes eutrophus subsp. Quinolinicus: Characteristic properties and chemical modifications.

The effects of quinolinic acid analogues and 5-phosphoribosyl-1-pyrophosphate analogues on the activity of quinolinate phosphoribosyltransferase (EC 2.4.2.19) crystallized from Alcaligenes eutrophus subsp. quinolinicus have been investigated. Sugar and metal contents, amino acid composition and active site of the crystalline enzyme were also examined. The C-2 carboxyl group and pyridine ring of quinolinic acid and 5-phosphate of 5-phosphoribosyl-1-pyrophosphate took part in the binding to the enzyme. This enzyme did not contain metal and was found to contain sugar about 1 % as mannose. The amino acid composition of this enzyme was compared with that of hog liver enzyme. Sulfhydryl, amino and imidazole groups may exist in the active site of the enzyme.

Identification of quinolinic acid-utilizing bacteria.

A microorganism utilizing quinolinic acid as sole carbon, nitrogen, and energy sources for growth, and producing a potent activity of quinolinate phosphoribosyltransferase in its cells was isolated. Based on its morphological, cultural, physiological, and biochemical characteristics, including the proper composition of cellular fatty acids, Alcaligenes eutrophus subsp. quinolinicus subsp. nov. KOUNO and IWAI is proposed for this organism.

Effect of dietary protein level on some key enzymes of the tryptophan-NAD pathway

1. Six groups of rats were given diets containing protein at three levels (50, 100 and 200 g/kg), with and without nicotinic acid. After 4 weeks on these diets some key enzymes of the tryptophan and nicotinic acid-NAD pathway, liver nicotinamide nucleotide concentration, and urinary metabolites of tryptophan and nicotinic acid were studied. 2. Liver nicotinamide nucleotide levels were lower in rats given the diet with 50 g protein/kg as compared to those in rats given diets with 100 and 200 g protein/kg. The addition of nicotinic acid to the diet resulted in a significant increase in the levels of nicotinamide nucleotides only in rats given 50 g protein/kg diet but not in those given either 100 or 200 g protein/kg diet. 3. Liver tryptophan oxygenase (EC 1.13.1.12) activity increased with increasing dietary protein level. Niconitic acid in the diet had no effect on its activity. 4. Quinolinate phosphoribosyltransferase (EC 2.4.2.a) activity in liver was inversely related to dietary protein level, and nicotinic acid in the diet had no effect on its activity. 5. Liver nicotinate phosphoribosyltransferase (EC 2.4.2.11) activity and kidney picolinate carboxylase (EC 4.1.1.45) activity were not altered either by dietary protein level or nicotinic acid in the diet. 6. The addition of nicotinic acid to the diet resulted in increased excretion of N'-methylnicotinamide at all dietary protein levels. 7. The inverse relationship between protein level in the diet and liver quinolinate phosphoribosyltransferase activity, the rate-limiting enzyme of the tryptophan-NAD pathway suggests that the efficiency of conversion of tryptophan to NAD is related to protein level in the diet, the efficiency decreasing with an increase in the level of dietary protein.

Effect of protein level in the diet on quinolinate phosphoribosyltransferase of rat liver

Quinolinate phosphoribosyl-transferase is the rate limiting enzyme in the NAD pathway of tryptophan metabolism. Results of a preliminary study reported here have indicated an inverse relationship between dietary protein and activity of liver quinolinate phosphoribosyltransferase. An elevated activity of quinolinate phosphoribosyl-transferase on a low protein diet may represent an adaptive mechanism for efficient utilisation of limited dietary tryptophan for synthesis of NAD.

Purification and properties of quinolinate phosphoribosyltransferase from the "shitake" mushroom (Lentinus edodes).

A considerably high activity of quinolinate phosphoribosyltransferase, an intermediary enzyme in the de novo NAD biosynthetic pathway, was found in a soluble fraction of the “Shiitake” mushroom extract. Highly purified enzyme (approximately 1, 000-fold, chromatography-cally pure) was extracted for the first time from mushrooms and its general properties were investigated. An apparent molecular weight of 1.6×105 was estimated by the gel filtration method. The optimum pH for the reaction was 6.5. The reaction required a divalent cation in addition to quinolinic acid and PRPP. Michaelis constants for quinolinic acid, PRPP and Mg++ were 1.1×10-5 M, 2.3×10-5M and 2.0×10-4M, respectively. The reaction product was identified as nicotinic acid mononucleotide by KCN addition reaction and by paper partition chromatography.

Effect of leucine on enzymes of the tryptophan–niacin metabolic pathway in rat liver and kidney

Dietary excess of leucine affects tryptophan-niacin metabolism adversely and has thus been implicated in the etiology of pellagra. To understand the biochemical basis of leucine-induced changes in tryptophan-niacin metabolism the effect of leucine on enzymes of tryptophan-niacin metabolism was investigated. Excess of leucine in the diet had no effect on rat liver 3-hydroxyanthranilate oxygenase and nicotinate phosphoribosyltransferase but significantly decreased the activity of quinolinate phosphoribosyltransferase of rat liver and kidney. The activities of tryptophan oxygenase in liver and picolinate carboxylase in kidney were significantly higher in leucine-fed animals than in the controls. Also, oxidation of [U-(14)C]tryptophan in vivo was higher in leucine-fed animals. Increased picolinate carboxylase and decreased quinolinate phosphoribosyltransferase activities would result in a decrease in NAD formation from dietary tryptophan. Lowered NAD formation from tryptophan particularly when the niacin concentrations in the diet are marginal would result in a state of conditioned niacin deficiency.