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Pathway Description
Purine Nucleotides De Novo Biosynthesis
Escherichia coli
Metabolic Pathway
The biosynthesis of purine nucleotides is a complex process that begins with a phosphoribosyl pyrophosphate. This compound interacts with water and L-glutamine through a
amidophosphoribosyl transferase resulting in a pyrophosphate, L-glutamic acid and a 5-phosphoribosylamine. The latter compound proceeds to interact with a glycine through an ATP driven phosphoribosylamine-glycine ligase resulting in the addition of glycine to the compound. This reaction releases an ADP, a phosphate, a hydrogen ion and a N1-(5-phospho-β-D-ribosyl)glycinamide. The latter compound interacts with formic acid, through an ATP driven phosphoribosylglycinamide formyltransferase 2 resulting in a phosphate, an ADP, a hydrogen ion and a 5-phosphoribosyl-N-formylglycinamide. The latter compound interacts with L-glutamine, and water through an ATP-driven
phosphoribosylformylglycinamide synthetase resulting in a release of a phosphate, an ADP, a hydrogen ion, a L-glutamic acid and a 2-(formamido)-N1-(5-phospho-D-ribosyl)acetamidine. The latter compound interacts with an ATP driven phosphoribosylformylglycinamide cyclo-ligase resulting in a release of ADP, a phosphate, a hydrogen ion and a 5-aminoimidazole ribonucleotide. The latter compound interacts with a hydrogen carbonate through an ATP driven N5-carboxyaminoimidazole ribonucleotide synthetase resulting in a release of a phosphate, an ADP, a hydrogen ion and a N5-carboxyaminoimidazole ribonucleotide.The latter compound then interacts with a N5-carboxyaminoimidazole ribonucleotide mutase resulting in a 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxylate. This compound interacts with an L-aspartic acid through an ATP driven phosphoribosylaminoimidazole-succinocarboxamide synthase resulting in a phosphate, an ADP, a hydrogen ion and a SAICAR. SAICAR interacts with an adenylosuccinate lyase resulting in a fumaric acid and an AICAR. AICAR interacts with a formyltetrahydrofolate through a AICAR transformylase / IMP cyclohydrolase resulting in a release of a tetrahydropterol mono-l-glutamate and a FAICAR. The latter compound, FAICAR, interacts in a reversible reaction through a AICAR transformylase / IMP cyclohydrolase resulting in a release of water and Inosinic acid.
Inosinic acid can be metabolized to produce dGTP and dATP three different methods each.
dGTP:
Inosinic acid, water and NAD are processed by IMP dehydrogenase resulting in a release of NADH, a hydrogen ion and Xanthylic acid. Xanthylic acid interacts with L-glutamine, and water through an ATP driven GMP synthetase resulting in pyrophosphate, AMP, L-glutamic acid, a hydrogen ion and Guanosine monophosphate. The latter compound is the phosphorylated by reacting with an ATP driven guanylate kinase resulting in a release of ADP and a Gaunosine diphosphate. Guanosine diphosphate can be metabolized in three different ways:
1.-Guanosine diphosphate is phosphorylated by an ATP-driven nucleoside diphosphate kinase resulting in an ADP and a Guanosine triphosphate. This compound interacts with a reduced flavodoxin protein through a ribonucleoside-triphosphate reductase resulting in a oxidized flavodoxin a water moleculer and a dGTP
2.-Guanosine diphosphate interacts with a reduced NrdH glutaredoxin-like proteins through a ribonucleoside-diphosphate reductase 2 resulting in the release of an oxidized NrdH glutaredoxin-like protein, a water molecule and a dGDP. The dGDP is then phosphorylated by interacting with an ATP-driven nucleoside diphosphate kinase resulting in an ADP and dGTP.
3.-Guanosine diphosphate interacts with a reduced thioredoxin ribonucleoside diphosphate reductase 1 resulting in a release of a water molecule, an oxidized thioredoxin and a dGDP. The dGDP is then phosphorylated by interacting with an ATP-driven nucleoside diphosphate kinase resulting in an ADP and dGTP.
dATP:
Inosinic acid interacts with L-aspartic acid through an GTP driven adenylosuccinate synthase results in the release of GDP, a hydrogen ion, a phosphate and N(6)-(1,2-dicarboxyethyl)AMP. The latter compound is then cleaved by a adenylosuccinate lyase resulting in a fumaric acid and an Adenosine monophosphate. This compound is then phosphorylated by an adenylate kinase resulting in the release of ATP and an adenosine diphosphate. Adenosine diphosphate can be metabolized in three different ways:
1.-Adenosine diphosphate is involved in a reversible reaction by interacting with a hydrogen ion and a phosphate through a ATP synthase / thiamin triphosphate synthase resulting in a hydrogen ion, a water molecule and an Adenosine triphosphate. The adenosine triphosphate interacts with a reduced flavodoxin through a ribonucleoside-triphosphate reductase resulting in an oxidized flavodoxin, a water molecule and a dATP
2.- Adenosine diphosphate interacts with an reduced thioredoxin through a ribonucleoside diphosphate reductase 1 resulting in a release of a water molecule, a oxidized thioredoxin and a dADP. The dADP is then phosphorylated by a nucleoside diphosphate kinase resulting in the release of ADP and a dATP
3.- Adenosine diphosphate interacts with an reduced NrdH glutaredoxin-like protein through a ribonucleoside diphosphate reductase 2 resulting in a release of a water molecule, a oxidized glutaredoxin-like protein and a dADP. The dADP is then phosphorylated by a nucleoside diphosphate kinase resulting in the release of ADP and a dATP
References
Purine Nucleotides De Novo Biosynthesis References
Meng LM, Kilstrup M, Nygaard P: Autoregulation of PurR repressor synthesis and involvement of purR in the regulation of purB, purC, purL, purMN and guaBA expression in Escherichia coli. Eur J Biochem. 1990 Jan 26;187(2):373-9.
Pubmed: 2404765
Neidhardt FC, Curtiss III R, Ingraham JL, Lin ECC, Low Jr KB, Magasanik B, Reznikoff WS, Riley M, Schaechter M, Umbarger HE. Escherichia coli and Salmonella, Cellular and Molecular Biology, Second Edition. American Society for Microbiology, Washington, D.C., 1996.
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