Structural characterization of the stringent response related exopolyphosphatase/guanosine pentaphosphate phosphohydrolase protein family.

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.

• Authors: Ole Kristensen, Martin Laurberg, Anders Liljas, Jette Sandholm Kastrup, Michael Gajhede
• Journal: Biochemistry (Biochemistry) Vol. 43 Issue 28 Pg. 8894-900 (Jul 20 2004) ISSN: 0006-2960 [Print] United States
• PMID: 15248747 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Bacterial Proteins
• Chlorine
• Acid Anhydride Hydrolases
• Pyrophosphatases
• exopolyphosphatase
• guanosine-5'-triphosphate, 3'-diphosphate pyrophosphatase
• Calcium

Topics

• Acid Anhydride Hydrolases (chemistry)
• Adaptation, Physiological
• Bacteria (enzymology)
• Bacterial Proteins (chemistry)
• Binding Sites
• Calcium
• Chlorine
• Crystallization
• Crystallography, X-Ray
• Models, Molecular
• Molecular Structure
• Pyrophosphatases (chemistry)