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Information on EC 2.4.2.8 - hypoxanthine phosphoribosyltransferase and Organism(s) Toxoplasma gondii and UniProt Accession Q26997

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EC Tree
     2 Transferases
         2.4 Glycosyltransferases
             2.4.2 Pentosyltransferases
                2.4.2.8 hypoxanthine phosphoribosyltransferase
IUBMB Comments
Guanine and purine-6-thiol can replace hypoxanthine.
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This record set is specific for:
Toxoplasma gondii
UNIPROT: Q26997
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The taxonomic range for the selected organisms is: Toxoplasma gondii
The enzyme appears in selected viruses and cellular organisms
Synonyms
hprt, hgprt, hypoxanthine-guanine phosphoribosyltransferase, hprt1, hypoxanthine phosphoribosyltransferase, hypoxanthine-guanine phosphoribosyl transferase, hypoxanthine phosphoribosyl transferase, hypoxanthine guanine phosphoribosyltransferase, hgprtase, guanine phosphoribosyltransferase, more
SYNONYM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
6-hydroxypurine phosphoribosyltransferase
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6-mercaptopurine phosphoribosyltransferase
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GMP pyrophosphorylase
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guanine phosphoribosyltransferase
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guanine-hypoxanthine phosphoribosyltransferase
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guanosine 5'-phosphate pyrophosphorylase
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guanosine phosphoribosyltransferase
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guanylate pyrophosphorylase
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guanylic pyrophosphorylase
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HGPRT
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HGPRTase
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hypoxanthine-guanine phosphoribosyltransferase
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hypoxanthine-xanthine-guanine phosphoribosyltransferase
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IMP pyrophosphorylase
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IMP-GMP pyrophosphorylase
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inosinate pyrophosphorylase
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inosine 5'-phosphate pyrophosphorylase
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inosinic acid pyrophosphorylase
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inosinic pyrophosphorylase
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phosphoribosyltransferase, 6-mercaptopurine
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phosphoribosyltransferase, hypoxanthine
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purine-6-thiol phosphoribosyltransferase
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transphosphoribosidase
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
IMP + diphosphate = hypoxanthine + 5-phospho-alpha-D-ribose 1-diphosphate
show the reaction diagram
IMP + diphosphate = hypoxanthine + 5-phospho-alpha-D-ribose 1-diphosphate
show the reaction diagram
REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
pentosyl group transfer
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SYSTEMATIC NAME
IUBMB Comments
IMP:diphosphate phospho-D-ribosyltransferase
Guanine and purine-6-thiol can replace hypoxanthine.
CAS REGISTRY NUMBER
COMMENTARY hide
9016-12-0
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SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
guanine + 5-phospho-alpha-D-ribose 1-diphosphate
GMP + diphosphate
show the reaction diagram
hypoxanthine + 5-phospho-alpha-D-ribose 1-diphosphate
IMP + diphosphate
show the reaction diagram
xanthine + 5-phospho-alpha-D-ribose 1-diphosphate
XMP + diphosphate
show the reaction diagram
guanine + 5-phospho-alpha-D-ribose 1-diphosphate
GMP + diphosphate
show the reaction diagram
hypoxanthine + 5-phospho-alpha-D-ribose 1-diphosphate
IMP + diphosphate
show the reaction diagram
additional information
?
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NATURAL SUBSTRATE
NATURAL PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
guanine + 5-phospho-alpha-D-ribose 1-diphosphate
GMP + diphosphate
show the reaction diagram
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-
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-
?
hypoxanthine + 5-phospho-alpha-D-ribose 1-diphosphate
IMP + diphosphate
show the reaction diagram
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?
additional information
?
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salvage incorporation of exogenous purine nucleotides, no de novo synthesis
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?
METALS and IONS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
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isozyme HXGPRT-I lacking the 49-amino acid insertion
Manually annotated by BRENDA team
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isozyme HXGPRT-II possessisng the 49-amino acid insertion, localizes to the inner membrane complex (IMC) of the parasite
Manually annotated by BRENDA team
additional information
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differential localization of alternatively spliced isozymes, overview
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Manually annotated by BRENDA team
UNIPROT
ENTRY NAME
ORGANISM
NO. OF AA
NO. OF TRANSM. HELICES
MOLECULAR WEIGHT[Da]
SOURCE
SEQUENCE
LOCALIZATION PREDICTION?
HGXR_TOXGO
230
0
26386
Swiss-Prot
other Location (Reliability: 1)
SUBUNIT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
tetramer
additional information
CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
crystallization in complex with GMP and IMP, structure analysis
mutant enzyme D150A, crystallization complexed with xanthosine 5'-monophosphate, diphosphate and 2 Mg2+, post transition state structure analysis, active site structure
the recombinant enzyme is complexed with Mg2+, 5-phosphoribosyl 1-diphosphate and inactive substrate analogue 9-deazaguanine, hanging drop method, enzyme complex, 20 mg/ml, is precipitated by 0.1 M Tris-HCl, pH 8.0, 30% polyethylene glycol 4000, 0.2 M Li2SO4, 0.5% beta-octylglucoside at 4°C, X-ray diffraction structure analysis
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PROTEIN VARIANTS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
D150A
reduced activity compared to wild-type, kcat for hypoxanthine, guanine, and xanthine are reduced by 11fold, 296fold, and 8.6fold, respectively, Km value for alpha-D-5-phosphoribosyl 1-diphosphate is reduced by 6.5fold
additional information
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chimeric constructs expressing N-terminal peptides of 11 amino acids from isoform I or of 60 amino acids from isoform II fused to a chloramphenicol acetyl transferase reporter show that the N-terminal domain of isoform II is both necessary and sufficient for membrane association
PURIFICATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
recombinant enzyme
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CLONED (Commentary)
ORGANISM
UNIPROT
LITERATURE
gene HXGPRT, two isozymes, genetic organization, expression analysis of two alternative-splicing-derived isozymes, which differ in the presence or absence of a 49-amino acid insertion, specified by a single differentially spliced exon, but exhibit similar temporal expression patterns, isozyme expression in parasites lacking the endogenous hxgprt gene, expression of isozyme I in the cytosol and of isozyme II inthe inner membrane complex in enzyme-deficient parasites, co-expression of both isoforms results in the formation of heterooligomers, which distribute between the cytosol and IMC
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APPLICATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
medicine
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potential target for antiparasitic chemotherapy
REF.
AUTHORS
TITLE
JOURNAL
VOL.
PAGES
YEAR
ORGANISM (UNIPROT)
PUBMED ID
SOURCE
Heroux, A.; White, E.L.; Ross, L.J.; Davis, R.L.; Borhani, D.W.
Crystal structure of Toxoplasma gondii hypoxanthine-guanine phosphoribosyltransferase with XMP, pyrophosphate, and two Mg2+ Ions Bound: insights into the catalytic mechanism
Biochemistry
38
14495-14506
1999
Toxoplasma gondii (Q26997), Toxoplasma gondii
Manually annotated by BRENDA team
Heroux, A.; White, E.L.; Ross, L.J.; Borhani, D.W.
Crystal structures of the Toxoplasma gondii hypoxanthine-guanine phosphoribosyltransferase-GMP and -IMP complexes: comparison of purine binding interactions with the XMP complex
Biochemistry
38
14485-14494
1999
Toxoplasma gondii (Q26997), Toxoplasma gondii
Manually annotated by BRENDA team
Heroux, A.; White, E.L.; Ross, L.J.; Kuzin, A.P.; Borhani, D.W.
Substrate deformation in a hypoxanthine-guanine phosphoribosyltransferase ternary complex: the structural basis for catalysis
Structure Fold. Des.
8
1309-1318
2000
Toxoplasma gondii
Manually annotated by BRENDA team
Chaudhary, K.; Donald, R.G.; Nishi, M.; Carter, D.; Ullman, B.; Roos, D.S.
Differential localization of alternatively spliced hypoxanthine-xanthine-guanine phosphoribosyltransferase isoforms in Toxoplasma gondii
J. Biol. Chem.
280
22053-22059
2005
Toxoplasma gondii
Manually annotated by BRENDA team