If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
Locations of Mapped Genes:
|Superclasses:||Biosynthesis → Nucleosides and Nucleotides Biosynthesis → Purine Nucleotide Biosynthesis → Purine Nucleotides De Novo Biosynthesis|
The first purine nucleotide that is synthesized de novo is IMP (IMP). IMP is converted to XMP (XMP) by the enzyme IMP dehydrogenase, and the later is converted to the first guanosine nucleotide, GMP (GMP), by the action of GMP synthetase, an enzyme that can use either glutamine or ammonia as substrate. GMP is then converted to GDP (GDP) and subsequently to GTP (GTP) by the enzymes guanylate kinase and nucleoside diphosphate kinase, respectively.
In Escherichia coli both GDP and GTP can be converted to the deoxy forms of the nucleotide. GTP is converted to dGTP (dGTP) by the uncommon enzyme ribonucleoside-triphosphate reductase, while GDP can be converted to dGDP (dGDP) by either ribonucleoside diphosphate reductase 1 or ribonucleoside-diphosphate reductase 2.
Finally, nucleoside diphosphate kinase can also convert dGDP to dGTP.
In bacterial systems genetic studies indicate that the majority of de novo purine biosynthetic genes are unlinked but may act as a single unit of regulation controlled by the `purR' repressor protein [Meng90].
Superpathways: superpathway of purine nucleotides de novo biosynthesis II
Variants: superpathway of adenosine nucleotides de novo biosynthesis I , superpathway of adenosine nucleotides de novo biosynthesis II , superpathway of guanosine nucleotides de novo biosynthesis I , superpathway of purine nucleotides de novo biosynthesis I
Meng90: Meng LM, Kilstrup M, Nygaard P (1990). "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;187(2);373-9. PMID: 2404765
Dyson90: Dyson HJ, Gippert GP, Case DA, Holmgren A, Wright PE (1990). "Three-dimensional solution structure of the reduced form of Escherichia coli thioredoxin determined by nuclear magnetic resonance spectroscopy." Biochemistry 1990;29(17);4129-36. PMID: 2193685
Eklund84: Eklund H, Cambillau C, Sjoberg BM, Holmgren A, Jornvall H, Hoog JO, Branden CI (1984). "Conformational and functional similarities between glutaredoxin and thioredoxins." EMBO J 1984;3(7);1443-9. PMID: 6378624
Nikkola93: Nikkola M, Gleason FK, Fuchs JA, Eklund H (1993). "Crystal structure analysis of a mutant Escherichia coli thioredoxin in which lysine 36 is replaced by glutamic acid." Biochemistry 1993;32(19);5093-8. PMID: 8098620
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