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Literature summary for 2.4.2.7 extracted from

  • Huyet, J.; Ozeir, M.; Burgevin, M.C.; Pinson, B.; Chesney, F.; Remy, J.M.; Siddiqi, A.R.; Lupoli, R.; Pinon, G.; Saint-Marc, C.; Gibert, J.F.; Morales, R.; Ceballos-Picot, I.; Barouki, R.; Daignan-Fornier, B.; Olivier-Bandini, A.; Auge, F.; Nioche, P.
    Structural insights into the forward and reverse enzymatic reactions in human adenine phosphoribosyltransferase (2018), Cell Chem. Biol., 25, 666-676.e4 .
    View publication on PubMed
Search for more literature for 2.4.2.7

Cloned(Commentary)

Cloned (Comment) Organism
recombinant expression of wild-type and mutant hAPRTs in an APRT-free Saccharomyces cerevisiae strain, which is defective for de novo purine synthesis (strain DS1-2b) an extremely low intracellular concentration of ATP in yeast expressing both variants (Glu104Leu or Tyr105Phe) is observed Homo sapiens

Crystallization (Commentary)

Crystallization (Comment) Organism
comparison of the crystal structure of PRPP-Mg2+-bound hAPRT to the ADE/PRPP-Mg2+ and AMP complex structures Homo sapiens

Protein Variants

Protein Variants Comment Organism
E104L site-directed mutagenesis, the mutation decreases the catalytic efficiency of the enzyme in the forward reaction Homo sapiens
additional information Saccharomyces cerevisiae strain DS1-2b expressing the Tyr105Phe variant of hAPRT displays a reduced growth rate in absence of exogenous adenine, similar to the Glu104Leu variant, compared with the wild-type Homo sapiens
Y105F site-directed mutagenesis, the mutation increases the inhibitory effect of AMP while decreasing the catalytic efficiency of the enzyme in the forward reaction Homo sapiens

Inhibitors

Inhibitors Comment Organism Structure
AMP 5-phospho-alpha-D-ribose 1-diphosphate and AMP compete for the same site where the latter also acts as a competitive inhibitor of the forward reaction. Tyr105 prevents strong inhibition of hAPRT by AMP Homo sapiens

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
0.00085
-
 5-phospho-alpha-D-ribose 1-diphosphate pH 7.5, 23°C, recombinant mutant Y105F Homo sapiens
0.0029
-
 adenine pH 7.5, 23°C, recombinant mutant Y105F Homo sapiens
0.0047
-
 adenine pH 8.5, 23°C, recombinant mutant Y105F Homo sapiens
0.0061
-
 adenine pH 7.5, 23°C, recombinant wild-type enzyme Homo sapiens
0.0063
-
 adenine pH 8.5, 23°C, recombinant wild-type enzyme Homo sapiens
0.0168
-
 5-phospho-alpha-D-ribose 1-diphosphate pH 7.5, 23°C, recombinant wild-type enzyme Homo sapiens

Metals/Ions

Metals/Ions Comment Organism Structure
Mg2+ required, binding structure, overview Homo sapiens

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
adenine + 5-phospho-alpha-D-ribose 1-diphosphate Homo sapiens
-
 AMP + diphosphate
-
 r

Organism

Organism UniProt Comment Textmining
Homo sapiens P07741
-
-

Reaction

Reaction Comment Organism Reaction ID
AMP + diphosphate = adenine + 5-phospho-alpha-D-ribose 1-diphosphate the enzyme with reversible activities has an ordered sequential bibi reaction mechanism Homo sapiens
a

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
adenine + 5-phospho-alpha-D-ribose 1-diphosphate
-
 Homo sapiens AMP + diphosphate
-
 r
adenine + 5-phospho-alpha-D-ribose 1-diphosphate human APRT catalyzes the transformation of adenine into AMP and vice versa Homo sapiens AMP + diphosphate
-
 r
additional information both the PRPP and ADE substrates are well ordered in all four subunits of the enzyme's crystal asymmetric unit, substrates' binding structures, overview. Residue Tyr105 favors the forward reaction. Tyr105 is in contact with both adenine and PRPP substrates in the closed conformation of the flexible loop. It might therefore play a role in the enzyme catalytic processes Homo sapiens ?
-
-

Synonyms

Synonyms Comment Organism
APRT
-
 Homo sapiens
hAPRT
-
 Homo sapiens

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
23
-
 assay at Homo sapiens

Temperature Stability [°C]

Temperature Stability Minimum [°C] Temperature Stability Maximum [°C] Comment Organism
additional information
-
 compared with the substrate-free form, the unfolding temperature of the 5-phospho-alpha-D-ribose 1-diphosphate (PRPP)-bound enzyme is increased by 30°C, which suggests that PRPP protects the enzyme from thermodenaturation Homo sapiens

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
0.012
-
 adenine pH 8.5, 23°C, recombinant mutant Y105F Homo sapiens
0.013
-
 adenine pH 7.5, 23°C, recombinant mutant Y105F Homo sapiens
0.013
-
 5-phospho-alpha-D-ribose 1-diphosphate pH 7.5, 23°C, recombinant mutant Y105F Homo sapiens
0.26
-
 adenine pH 8.5, 23°C, recombinant wild-type enzyme Homo sapiens
3.85
-
 adenine pH 7.5, 23°C, recombinant wild-type enzyme Homo sapiens
3.85
-
 5-phospho-alpha-D-ribose 1-diphosphate pH 7.5, 23°C, recombinant wild-type enzyme Homo sapiens

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
7.5 8.5 assay at Homo sapiens

Ki Value [mM]

Ki Value [mM] Ki Value maximum [mM] Inhibitor Comment Organism Structure
0.0021
-
 AMP pH 7.5, 23°C, recombinant mutant Y105F Homo sapiens
0.023
-
 AMP pH 7.5, 23°C, recombinant wild-type enzyme Homo sapiens

General Information

General Information Comment Organism
evolution APRT refers to the type I phosphoribosyltransferase (PRT) family, which belongs to the large glycosyltransferase family Homo sapiens
malfunction APRT deficiencies in this enzyme lead to 2,8-dihydroxyadenine urolithiasis, and renal and allograft failures Homo sapiens
metabolism enzyme APRT is a key enzyme in the purine salvage pathway in prokaryotes and eukaryotes Homo sapiens
additional information the hydroxyl group in conserved tyrosine 105 controls the protein dynamics and the catalytic efficiencies of the forward and reverse reactions. Determination of the key residues of the reaction and the catalytic flexible loop dynamics. Tyr105 is essential for cell growth by facilitating the forward reaction. The active site of APRT consists of a 13-amino-acid-long PRPP-binding motif, starting from Val123 in hAPRT, with a conserved A131TGGS/T core sequence which serves to anchor the 5'-monophosphate group of either PRPP or ribonucleotides. It also contains two adjacent aspartates (Asp127 and Asp128 in hAPRT), two arginines (Arg67 and Arg87), and a specific cis-peptide bond, between Asp65 and Ser66, which hold together the 2'- and 3'-OH of the ribose and the diphosphate moiety of PRPP. Analysis of the role of hAPRT flexible loop Homo sapiens
physiological function phosphoribosyltransferases catalyze the displacement of a PRPP alpha-1'-diphosphate to a nitrogen-containing nucleobase. Phosphoribosyltransferase APRT residue Tyr105 is essential for cell growth by facilitating the forward reaction, The APRT Tyr105 drives purine biosynthesis in vivo. Tyr105 is key for the fine-tuning of the kinetic activity efficiencies of forward and reverse reactions. In crystallo activity shows that the hydroxyl group of Tyr105 is essential to select the bioactive conformation of the dynamic flexible loop and to form the products Homo sapiens

kcat/KM [mM/s]

kcat/KM Value [1/mMs-1] kcat/KM Value Maximum [1/mMs-1] Substrate Comment Organism Structure
2.6
-
 adenine pH 8.5, 23°C, recombinant mutant Y105F Homo sapiens
4.5
-
 adenine pH 7.5, 23°C, recombinant mutant Y105F Homo sapiens
15.3
-
 5-phospho-alpha-D-ribose 1-diphosphate pH 7.5, 23°C, recombinant mutant Y105F Homo sapiens
42.6
-
 adenine pH 8.5, 23°C, recombinant wild-type enzyme Homo sapiens
229.2
-
 5-phospho-alpha-D-ribose 1-diphosphate pH 7.5, 23°C, recombinant wild-type enzyme Homo sapiens
631.15
-
 adenine pH 7.5, 23°C, recombinant wild-type enzyme Homo sapiens