Abstract
Exopolyphosphatase/guanosine pentaphosphate phosphohydrolase (PPX/GPPA) enzymes play central roles in the bacterial stringent response induced by starvation. The high-resolution crystal structure of the putative Aquifex aeolicus PPX/GPPA phosphatase from the actin-like ATPase domain superfamily has been determined, providing the first insights to features of the common catalytic core of the PPX/GPPA family. The protein has a two-domain structure with an active site located in the interdomain cleft. Two crystal forms were investigated (type I and II) at resolutions of 1.53 and 2.15 A, respectively. This revealed a structural flexibility that has previously been described as a "butterfly-like" cleft opening around the active site in other actin-like superfamily proteins. A calcium ion is observed at the center of this region in type I crystals, substantiating that PPX/GPPA enzymes use metal ions for catalysis. Structural analysis suggests that nucleotides bind at a similar position to that seen in other members of the superfamily.
| Original language | English |
|---|---|
| Journal | Biochemistry |
| Volume | 43 |
| Issue number | 28 |
| Pages (from-to) | 8894-900 |
| Number of pages | 7 |
| ISSN | 0006-2960 |
| DOIs | |
| Publication status | Published - 2004 |
Keywords
- Acid Anhydride Hydrolases
- Adaptation, Physiological
- Bacteria
- Bacterial Proteins
- Binding Sites
- Calcium
- Chlorine
- Crystallization
- Crystallography, X-Ray
- Models, Molecular
- Molecular Structure
- Pyrophosphatases