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 | 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 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 | Comment | Organism | Structure |
---|---|---|---|
Mg2+ | required, high concentration of Mg2+ inhibit the reaction with a Ki = 5.4 mM | Saccharolobus solfataricus |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Saccharolobus solfataricus | Q97W95 | - |
- |
Saccharolobus solfataricus P2 | Q97W95 | - |
- |
Purification (Comment) | Organism |
---|---|
- |
Saccharolobus solfataricus |
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 | Comment | Organism |
---|---|---|
dimer | the enzyme forms dimers in solution and in the crystals | Saccharolobus solfataricus |
Synonyms | Comment | Organism |
---|---|---|
APRTase | - |
Saccharolobus solfataricus |
SSO2342 | locus name | Saccharolobus solfataricus |
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 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 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 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 |