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Literature summary for 2.4.2.7 extracted from

  • Jensen, K.F.; Hansen, M.R.; Jensen, K.S.; Christoffersen, S.; Poulsen, J.C.; Molgaard, A.; Kadziola, A.
    Adenine phosphoribosyltransferase from Sulfolobus solfataricus is an enzyme with unusual kinetic properties and a crystal structure that suggests it evolved from a 6-oxopurine phosphoribosyltransferase (2015), Biochemistry, 54, 2323-2334.
    View publication on PubMed

Crystallization (Commentary)

Crystallization (Comment) Organism
four crystal structures: (1) a structure (the enzyme/Pi complex) refined at 2.4 A with inorganic phosphate or sulfate bound in the 5-phosphoribosyl binding pocket, (2) an adenine bound structure (the enzyme/adenine complex) refined at 2.4 A, which shows adenine together with phosphates both at the 5'-phosphoryl and PPi positions of the presumed PRPP binding site, (3) an AMP bound structure (the enzyme/AMP complex) refined at 2.4 A, and (4) an ADP bound structure (the enzyme/ADP complex), refined at 2.8 A containing the inhibitor ADP bound like AMP with both the alpha- and beta-phosphates occupying the 5'-phosphoribosyl binding site. No crystals of the enzyme in complex with 5-phosphoribosyl-alpha-1-pyrophosphate are obtained, likely because the enzyme catalyzes a slow breakdown of 5-phosphoribosyl-alpha-1-pyrophosphate to ribose 5-phosphate and PPi. The crystal structure suggests that the enzyme evolves from a 6-oxopurine phosphoribosyltransferase. The individual subunit adopts an overall structure that resembles a 6-oxopurine phosphoribosyltransferase (PRTase) more than known adenine phosphoribosyltransferases implying that adenine phosphoribosyltransferase functionality in Crenarchaeotae has its evolutionary origin in this family of 6-oxopurine phosphoribosyltransferases. The N-terminal two-thirds of the polypeptide chain folds as a traditional type I PRTase with a five-stranded beta-sheet surrounded by helices. The C-terminal third adopts an unusual three-helix bundle structure that together with the nucleobase-binding loop undergoes a conformational change upon binding of adenine and phosphate resulting in a slight contraction of the active site Saccharolobus solfataricus

Inhibitors

Inhibitors Comment Organism Structure
adenine
-
Saccharolobus solfataricus
ADP the inhibitor binds like the product AMP with both the alpha- and beta-phosphates occupying the 5'-phosphoribosyl binding site Saccharolobus solfataricus
Mg2+ required, high concentration of Mg2+ inhibited the reaction with a Ki = 5.4 mM Saccharolobus solfataricus

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
0.0004
-
adenine 60°C, pH 7.4 Saccharolobus solfataricus
0.00059
-
adenine 36°C, pH 7.5 Saccharolobus solfataricus
0.0013
-
adenine 36°C, pH 7.9 Saccharolobus solfataricus
0.0106
-
adenine 60°C, pH 4.1 Saccharolobus solfataricus
0.0219
-
5-phospho-alpha-D-ribose 1-diphosphate 60°C, pH 4.1 Saccharolobus solfataricus
0.115
-
5-phospho-alpha-D-ribose 1-diphosphate 60°C, pH 7.4 Saccharolobus solfataricus

Metals/Ions

Metals/Ions Comment Organism Structure
Mg2+ required, high concentration of Mg2+ inhibit the reaction with a Ki = 5.4 mM Saccharolobus solfataricus

Organism

Organism UniProt Comment Textmining
Saccharolobus solfataricus Q97W95
-
-
Saccharolobus solfataricus P2 Q97W95
-
-

Purification (Commentary)

Purification (Comment) Organism
-
Saccharolobus solfataricus

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
adenine + 5-phospho-alpha-D-ribose 1-diphosphate
-
Saccharolobus solfataricus AMP + diphosphate
-
?
adenine + 5-phospho-alpha-D-ribose 1-diphosphate
-
Saccharolobus solfataricus P2 AMP + diphosphate
-
?

Subunits

Subunits Comment Organism
dimer the enzyme forms dimers in solution and in the crystals Saccharolobus solfataricus

Synonyms

Synonyms Comment Organism
APRTase
-
Saccharolobus solfataricus
SSO2342 locus name Saccharolobus solfataricus

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
5
-
5-phospho-alpha-D-ribose 1-diphosphate 60°C, pH 4.1 Saccharolobus solfataricus
5.3
-
adenine 60°C, pH 4.1 Saccharolobus solfataricus
5.4
-
adenine 60°C, pH 7.4 Saccharolobus solfataricus
7.2
-
5-phospho-alpha-D-ribose 1-diphosphate 60°C, pH 7.4 Saccharolobus solfataricus

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
4
-
the enzyme displays optima both at pH values around 4 and at pH 7-8 Saccharolobus solfataricus
7 8 the enzyme displays optima both at pH values around 4 and at pH 7-8 Saccharolobus solfataricus

pH Range

pH Minimum pH Maximum Comment Organism
3.5 9.5 the enzyme is active over a wide pH range Saccharolobus solfataricus

Ki Value [mM]

Ki Value [mM] Ki Value maximum [mM] Inhibitor Comment Organism Structure
0.011
-
adenine pH 7.5, 60°C Saccharolobus solfataricus
5.4
-
Mg2+ pH and temperature not specified in the publication Saccharolobus solfataricus