The molecular basis of phosphite and hypophosphite recognition by ABC-transporters

Nat Commun. 2017 Nov 23;8(1):1746. doi: 10.1038/s41467-017-01226-8.


Inorganic phosphate is the major bioavailable form of the essential nutrient phosphorus. However, the concentration of phosphate in most natural habitats is low enough to limit microbial growth. Under phosphate-depleted conditions some bacteria utilise phosphite and hypophosphite as alternative sources of phosphorus, but the molecular basis of reduced phosphorus acquisition from the environment is not fully understood. Here, we present crystal structures and ligand binding affinities of periplasmic binding proteins from bacterial phosphite and hypophosphite ATP-binding cassette transporters. We reveal that phosphite and hypophosphite specificity results from a combination of steric selection and the presence of a P-H…π interaction between the ligand and a conserved aromatic residue in the ligand-binding pocket. The characterisation of high affinity and specific transporters has implications for the marine phosphorus redox cycle, and might aid the use of phosphite as an alternative phosphorus source in biotechnological, industrial and agricultural applications.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • ATP-Binding Cassette Transporters / chemistry*
  • ATP-Binding Cassette Transporters / genetics
  • ATP-Binding Cassette Transporters / metabolism*
  • Amino Acid Sequence
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Binding Sites
  • Crystallography, X-Ray
  • Kinetics
  • Ligands
  • Models, Molecular
  • Phosphinic Acids / metabolism*
  • Phosphites / metabolism*
  • Phylogeny
  • Prochlorococcus / genetics
  • Prochlorococcus / metabolism
  • Pseudomonas stutzeri / genetics
  • Pseudomonas stutzeri / metabolism
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Sequence Homology, Amino Acid
  • Trichodesmium / genetics
  • Trichodesmium / metabolism


  • ATP-Binding Cassette Transporters
  • Bacterial Proteins
  • Ligands
  • Phosphinic Acids
  • Phosphites
  • Recombinant Proteins