Crystal structure of the phosphate-binding protein (PBP-1) of an ABC-type phosphate transporter from Clostridium perfringens

Sci Rep. 2014 Oct 16;4:6636. doi: 10.1038/srep06636.

Abstract

Phosphate limitation is an important environmental stress that affects the metabolism of various organisms and, in particular, can trigger the virulence of numerous bacterial pathogens. Clostridium perfringens, a human pathogen, is one of the most common causes of enteritis necroticans, gas gangrene and food poisoning. Here, we focused on the high affinity phosphate-binding protein (PBP-1) of an ABC-type transporter, responsible for cellular phosphate uptake. We report the crystal structure (1.65 Å resolution) of the protein in complex with phosphate. Interestingly, PBP-1 does not form the short, low-barrier hydrogen bond with phosphate that is typical of previously characterized phosphate-binding proteins, but rather a canonical hydrogen bond. In its unique binding configuration, PBP-1 forms an unusually high number of hydrogen bonds (14) with the phosphate anion. Discrimination experiments reveal that PBP-1 is the least selective PBP characterised so far and is able to discriminate phosphate from its close competing anion, arsenate, by ~150-fold.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arsenates / chemistry
  • Clostridium Infections / metabolism
  • Clostridium Infections / pathology
  • Clostridium perfringens / chemistry*
  • Clostridium perfringens / pathogenicity
  • Crystallography, X-Ray*
  • Humans
  • Hydrogen Bonding
  • Phosphate-Binding Proteins / chemistry*
  • Phosphate-Binding Proteins / metabolism
  • Phosphates / chemistry*
  • Protein Conformation

Substances

  • Arsenates
  • Phosphate-Binding Proteins
  • Phosphates
  • arsenic acid