The Structure of the Exopolyphosphatase (PPX) from Escherichia coli O157:H7 Suggests a Binding Mode for Long Polyphosphate Chains

Download
  1. Get@NRC: The Structure of the Exopolyphosphatase (PPX) from Escherichia coli O157:H7 Suggests a Binding Mode for Long Polyphosphate Chains (Opens in a new window)
DOIResolve DOI: http://doi.org/10.1016/j.jmb.2006.04.031
AuthorSearch for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for:
TypeArticle
Journal titleJ Mol Biol
Volume359
Issue5
Pages12491260; # of pages: 12
Subjectanalysis; Cells; Enzymes; Escherichia coli; I; pha; phosphatase; Protein; Proteins; RNA-Binding Proteins; Stress
AbstractPolyphosphate (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 A 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
Publication date
LanguageEnglish
AffiliationNRC Biotechnology Research Institute; National Research Council Canada
Peer reviewedNo
NRC number47524
NPARC number3539304
Export citationExport as RIS
Report a correctionReport a correction
Record identifier9bb244d6-f109-46b2-ab0f-4a3189248b57
Record created2009-03-01
Record modified2016-05-09
Bookmark and share
  • Share this page with Facebook (Opens in a new window)
  • Share this page with Twitter (Opens in a new window)
  • Share this page with Google+ (Opens in a new window)
  • Share this page with Delicious (Opens in a new window)