Enzymes
UniProtKB help_outline | 34,574 proteins |
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- Name help_outline IMP Identifier CHEBI:58053 Charge -2 Formula C10H11N4O8P InChIKeyhelp_outline GRSZFWQUAKGDAV-KQYNXXCUSA-L SMILEShelp_outline O[C@@H]1[C@@H](COP([O-])([O-])=O)O[C@H]([C@@H]1O)n1cnc2c1nc[nH]c2=O 2D coordinates Mol file for the small molecule Search links Involved in 20 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline diphosphate Identifier CHEBI:33019 (Beilstein: 185088) help_outline Charge -3 Formula HO7P2 InChIKeyhelp_outline XPPKVPWEQAFLFU-UHFFFAOYSA-K SMILEShelp_outline OP([O-])(=O)OP([O-])([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 1,139 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline hypoxanthine Identifier CHEBI:17368 (CAS: 68-94-0) help_outline Charge 0 Formula C5H4N4O InChIKeyhelp_outline FDGQSTZJBFJUBT-UHFFFAOYSA-N SMILEShelp_outline O=c1[nH]cnc2nc[nH]c12 2D coordinates Mol file for the small molecule Search links Involved in 14 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline 5-phospho-α-D-ribose 1-diphosphate Identifier CHEBI:58017 Charge -5 Formula C5H8O14P3 InChIKeyhelp_outline PQGCEDQWHSBAJP-TXICZTDVSA-I SMILEShelp_outline O[C@H]1[C@@H](O)[C@H](O[C@@H]1COP([O-])([O-])=O)OP([O-])(=O)OP([O-])([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 22 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
RHEA:17973 | RHEA:17974 | RHEA:17975 | RHEA:17976 | |
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Publications
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Lethal accumulation of guanylic nucleotides in Saccharomyces cerevisiae HPT1-deregulated mutants.
Breton A., Pinson B., Coulpier F., Giraud M.F., Dautant A., Daignan-Fornier B.
Guanylic nucleotide biosynthesis is a conserved and highly regulated process. Drugs reducing GMP synthesis affect the immunological response and mutations enabling guanylic-derivative recycling lead to severe mental retardation. While the effects of decreased GMP synthesis have been well documente ... >> More
Guanylic nucleotide biosynthesis is a conserved and highly regulated process. Drugs reducing GMP synthesis affect the immunological response and mutations enabling guanylic-derivative recycling lead to severe mental retardation. While the effects of decreased GMP synthesis have been well documented, the consequences of GMP overproduction in eukaryotes are poorly understood. In this work, we selected and characterized several mutations making yeast hypoxanthine-guanine phosphoribosyltransferase insensitive to feedback inhibition by GMP. In these mutants, accumulation of guanylic nucleotides can be triggered by addition of extracellular guanine. We show that such an accumulation is highly toxic for yeast cells and results in arrest of proliferation and massive cell death. This growth defect could be partially suppressed by overexpression of Rfx1p, a transcriptional repressor of the DNA damage response pathway. Importantly, neither guanylic nucleotide toxicity nor its suppression by Rfx1p was associated with an alteration of forward mutation frequency. << Less
Genetics 178:815-824(2008) [PubMed] [EuropePMC]
This publication is cited by 1 other entry.
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Crystal structures of free, IMP-, and GMP-bound Escherichia coli hypoxanthine phosphoribosyltransferase.
Guddat L.W., Vos S., Martin J.L., Keough D.T., de Jersey J.
Crystal structures have been determined for free Escherichia coli hypoxanthine phosphoribosyltransferase (HPRT) (2.9 A resolution) and for the enzyme in complex with the reaction products, inosine 5'-monophosphate (IMP) and guanosine 5'-monophosphate (GMP) (2.8 A resolution). Of the known 6-oxopur ... >> More
Crystal structures have been determined for free Escherichia coli hypoxanthine phosphoribosyltransferase (HPRT) (2.9 A resolution) and for the enzyme in complex with the reaction products, inosine 5'-monophosphate (IMP) and guanosine 5'-monophosphate (GMP) (2.8 A resolution). Of the known 6-oxopurine phosphoribosyltransferase (PRTase) structures, E. coli HPRT is most similar in structure to that of Tritrichomonas foetus HGXPRT, with a rmsd for 150 Calpha atoms of 1.0 A. Comparison of the free and product bound structures shows that the side chain of Phe156 and the polypeptide backbone in this vicinity move to bind IMP or GMP. A nonproline cis peptide bond, also found in some other 6-oxopurine PRTases, is observed between Leu46 and Arg47 in both the free and complexed structures. For catalysis to occur, the 6-oxopurine PRTases have a requirement for divalent metal ion, usually Mg(2+) in vivo. In the free structure, a Mg(2+) is coordinated to the side chains of Glu103 and Asp104. This interaction may be important for stabilization of the enzyme before catalysis. E. coli HPRT is unique among the known 6-oxopurine PRTases in that it exhibits a marked preference for hypoxanthine as substrate over both xanthine and guanine. The structures suggest that its substrate specificity is due to the modes of binding of the bases. In E. coli HPRT, the carbonyl oxygen of Asp163 would likely form a hydrogen bond with the 2-exocyclic nitrogen of guanine (in the HPRT-guanine-PRib-PP-Mg(2+) complex). However, hypoxanthine does not have a 2-exocyclic atom and the HPRT-IMP structure suggests that hypoxanthine is likely to occupy a different position in the purine-binding pocket. << Less