If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
|Superclasses:||Biosynthesis → Cofactors, Prosthetic Groups, Electron Carriers Biosynthesis → NAD Metabolism|
Some taxa known to possess this pathway include : Nicotiana tabacum
Expected Taxonomic Range: Viridiplantae
The pyridine nucleotide NAD and NADP are ubiquitous coenzymes that may have impact on virtually every metabolic pathway in the cell [Noctor06] [Moat87]. The biosynthesis of NAD in plants is realized via two major routes the de novo synthesis of NAD (see NAD biosynthesis I (from aspartate)) and the pyridine nucleotide cycle (this pathway). The name of the latter was coined to summarize the various routes of degradation and salvage of pyridine compounds [Gholson66]. In dependence on the plant species investigated the pyridine nucleotide cycle may involve a varying number of steps emphasizing the flexibility of this pathway in response to organism-specific and/or environmental conditions [Wagner86b, Zheng04a, Zheng05, Ashihara05].
The pyridine nucleotide cycling pathway ensures the homeostatic replenishment of NAD when the coenzyme has been involved in NAD consuming reactions. The pathway is fairly similar to the bacterial variant (NAD salvage pathway I) with the exception that some enzymes, e.g. NMN amidohydrolase, NAD synthase (NH3-dependent) have not been identified in plants, and that plants are capable of by-passing enzymes under certain conditions, hence conferring a broader adaptability [Noctor06].
About This Pathway
The anaplerotic enzyme of the pyridine nucleotide cycle is quinolinic acid phosphoribosyltransferase (QPRtase) (NAD biosynthesis I (from aspartate)) forming β-nicotinate D-ribonucleotide (nicotinate mononucleotide, NaMN) which may be considered as the start compound of this cycle [Wagner84] [Sinclair00]. From there two different routes can be taken to produce nicotinate, an important intermediate that gives rise to several secondary metabolites, e.g. trigonelline (trigonelline biosynthesis).
The enzyme catalyzing the direct conversion to nicotinate, i.e. NaMN nucleosidase (synonym NaMN glycohydrolase - NaMN-Ghase) has been partially purified from tobacco. The other route comprises several enzymatic steps that include the formation of the main intermediates nicotinate adenine dinucleotide (NaAD), NAD, nicotinamide mononucleotide (NMN) and nicotinamide. The enzyme that catalyzes the final step of the formation of nicotinate from nicotinamide, i.e. nicotinamidase has been identified in several plants [Wagner86b, Joshi60, Ashihara05, Zheng05] indicating the main stream of this pathway. The reverse reaction catalyzed by nicotinamide phosphoribosyltransferase (NPRT) has not been detected in plants [Hunt04, Zheng05]. The final step closing the cycle by converting nicotinate to nicotinate mononucleotide (NaMN) is catalyzed by nicotinic acid phosphoribosyltransferase (Na-PRtase) [Wagner86a, Mann74]. This enzyme expressed a high affinity towards nicotinate but did not accept nicotinamide as its counterpart enzyme in animals [Wagner86b].
The pathway displays two additional routes that can be taken to form either nicotinamide from NMN or nicotinate mononucleotide (NaMN) from nicotinate. Both form the nucleotide riboside intermediates that are catabolized by 5'-nucleotidase and NMN nucleosidase (via NMN riboside) and nucleoside phosphorylase and nicotinate ribose kinase (via nicotinate riboside), respectively. Some of those activities and the nucleoside ribosides have been found in plants [Noctor06, Hunt04, Zheng05, Polya75, Eastwell82] but the enzymes remain to be further characterized.
Ashihara05: Ashihara H, Stasolla C, Yin Y, Loukanina N, Thorpe TA (2005). "De novo and salvage biosynthetic pathways of pyridine nucleotides and nicotinic acid conjugates in cultured plant cells." Plant Science, 169, 107-114.
Mann74: Mann DF, Byerrum RU (1974). "Activation of the de Novo Pathway for Pyridine Nucleotide Biosynthesis Prior to Ricinine Biosynthesis in Castor Beans." Plant Physiol 53(4);603-609. PMID: 16658750
Moat87: Moat AG, Foster JW (1987). "Biosynthesis and salvage pathway of pyridine nucleotides." In: Pyridine nucleotide coenzymes Part B, Chemical, biochemical, and medical aspects. Dolphin D, Avramovic O, Poulson R (eds.), John Wilwy & Sons, New York-Chichester-Brisbane-Toronto-Singapore, 1-24.
Noctor06: Noctor G, Queval G, Gakiere B (2006). "NAD(P) synthesis and pyridine nucleotide cycling in plants and their potential importance in stress conditions." J Exp Bot 57(8);1603-20. PMID: 16714307
Sinclair00: Sinclair SJ, Murphy KJ, Birch CD, Hamill JD (2000). "Molecular characterization of quinolinate phosphoribosyltransferase (QPRtase) in Nicotiana." Plant Mol Biol 44(5);603-17. PMID: 11198422
Zheng04a: Zheng XQ, Nagai C, Ashihara H (2004). "Pyridine nucleotide cycle and trigonelline (N-methylnicotinic acid) synthesis in developing leaves and fruits of Coffea arabica." Physiologia Plantarum, 122, 404-411.
Zheng05: Zheng XQ, Hayashibe E, Ashihara H (2005). "Changes in trigonelline (N-methylnicotinic acid) content and nicotinic acid metabolism during germination of mungbean (Phaseolus aureus) seeds." J Exp Bot 56(416);1615-23. PMID: 15837705
Baecker78: Baecker PA, Yung SG, Rodriguez M, Austin E, Andreoli AJ (1978). "Periplasmic localization of nicotinate phosphoribosyltransferase in Escherichia coli." J Bacteriol 1978;133(3);1108-12. PMID: 346557
Belenky07: Belenky P, Racette FG, Bogan KL, McClure JM, Smith JS, Brenner C (2007). "Nicotinamide riboside promotes Sir2 silencing and extends lifespan via Nrk and Urh1/Pnp1/Meu1 pathways to NAD+." Cell 129(3);473-84. PMID: 17482543
Dahmen67: Dahmen W, Webb B, Preiss J (1967). "The deamido-diphosphopyridine nucleotide and diphosphopyridine nucleotide pyrophosphorylases of Escherichia coli and yeast." Arch Biochem Biophys 1967;120(2);440-50. PMID: 4291828
Emanuelli01: Emanuelli M, Carnevali F, Saccucci F, Pierella F, Amici A, Raffaelli N, Magni G (2001). "Molecular cloning, chromosomal localization, tissue mRNA levels, bacterial expression, and enzymatic properties of human NMN adenylyltransferase." J Biol Chem 276(1);406-12. PMID: 11027696
Emanuelli99: Emanuelli M, Carnevali F, Lorenzi M, Raffaelli N, Amici A, Ruggieri S, Magni G (1999). "Identification and characterization of YLR328W, the Saccharomyces cerevisiae structural gene encoding NMN adenylyltransferase. Expression and characterization of the recombinant enzyme." FEBS Lett 455(1-2);13-7. PMID: 10428462
Hara03: Hara N, Yamada K, Terashima M, Osago H, Shimoyama M, Tsuchiya M (2003). "Molecular identification of human glutamine- and ammonia-dependent NAD synthetases. Carbon-nitrogen hydrolase domain confers glutamine dependency." J Biol Chem 278(13);10914-21. PMID: 12547821
Kahn86: Kahn DW, Anderson BM (1986). "Characterization of Haemophilus influenzae nucleotide pyrophosphatase. An enzyme of critical importance for growth of the organism." J Biol Chem 261(13);6016-25. PMID: 3009442
Kemmer01: Kemmer G, Reilly TJ, Schmidt-Brauns J, Zlotnik GW, Green BA, Fiske MJ, Herbert M, Kraiss A, Schlor S, Smith A, Reidl J (2001). "NadN and e (P4) are essential for utilization of NAD and nicotinamide mononucleotide but not nicotinamide riboside in Haemophilus influenzae." J Bacteriol 183(13);3974-81. PMID: 11395461
Misumi90: Misumi Y, Ogata S, Hirose S, Ikehara Y (1990). "Primary structure of rat liver 5'-nucleotidase deduced from the cDNA. Presence of the COOH-terminal hydrophobic domain for possible post-translational modification by glycophospholipid." J Biol Chem 265(4);2178-83. PMID: 2298743
Natalini86: Natalini P, Ruggieri S, Raffaelli N, Magni G (1986). "Nicotinamide mononucleotide adenylyltransferase. Molecular and enzymatic properties of the homogeneous enzyme from baker's yeast." Biochemistry 25(12);3725-9. PMID: 3013296
Nishiyama91: Nishiyama M, Horinouchi S, Kobayashi M, Nagasawa T, Yamada H, Beppu T (1991). "Cloning and characterization of genes responsible for metabolism of nitrile compounds from Pseudomonas chlororaphis B23." J Bacteriol 173(8);2465-72. PMID: 2013568
Pardee71: Pardee AB, Benz EJ, St Peter DA, Krieger JN, Meuth M, Trieshmann HW (1971). "Hyperproduction and purification of nicotinamide deamidase, a microconstitutive enzyme of Escherichia coli." J Biol Chem 1971;246(22);6792-6. PMID: 4399474
Raffaelli02: Raffaelli N, Sorci L, Amici A, Emanuelli M, Mazzola F, Magni G (2002). "Identification of a novel human nicotinamide mononucleotide adenylyltransferase." Biochem Biophys Res Commun 297(4);835-40. PMID: 12359228
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