2flo

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spinqualitylabelsall models 2flo, resolution 2.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal structure of exopolyphosphatase (PPX) from E. coli O157:H7

Overview

Polyphosphate (polyP) is a linear polymer consisting of tens to hundreds, of phosphate molecules joined together by high-energy anhydride bonds., These polymers are found in virtually all prokaryotic and eukaryotic cells, and perform many functions; prominent among them are the responses to many, stresses. Polyphosphate is synthesized by polyP kinase (PPK), using the, terminal phosphate of ATP as the substrate, and degraded to inorganic, phosphate by both endo- and exopolyphosphatases. Here we report the, crystal structure and analysis of the polyphosphate phosphatase PPX from, Escherichia coli O157:H7 refined at 2.2 Angstroms resolution. PPX is made, of four domains. Domains I and II display structural similarity with one, another and share the ribonuclease-H-like fold. Domain III bears, structural similarity to the N-terminal, HD domain of SpoT. Domain IV, the, smallest domain, has structural counterparts in cold-shock associated, RNA-binding proteins but is of unknown function in PPX. The putative PPX, active site is located at the interface between domains I and II. In the, crystal structure of PPX these two domains are close together and, represent the "closed" state. Comparison with the crystal structure of, PPX/GPPA from Aquifex aeolicus reveals close structural similarity between, domains I and II of the two enzymes, with the PPX/GPPA representing an, "open" state. A striking feature of the dimer is a deep S-shaped canyon, extending along the dimer interface and lined with positively charged, residues. The active site region opens to this canyon. We postulate that, this is a likely site of polyP binding.

About this Structure

2FLO is a Single protein structure of sequence from Escherichia coli. Active as Exopolyphosphatase, with EC number 3.6.1.11 Full crystallographic information is available from OCA.

Reference

The structure of the exopolyphosphatase (PPX) from Escherichia coli O157:H7 suggests a binding mode for long polyphosphate chains., Rangarajan ES, Nadeau G, Li Y, Wagner J, Hung MN, Schrag JD, Cygler M, Matte A, J Mol Biol. 2006 Jun 23;359(5):1249-60. Epub 2006 Apr 27. PMID:16678853

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