1.95A resolution structure of PtxB from Trichodesmium erythraeum IMS101 in complex with phosphite

Experimental Data Snapshot

  • Resolution: 1.95 Å
  • R-Value Free: 0.267 
  • R-Value Work: 0.215 
  • R-Value Observed: 0.218 

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This is version 1.2 of the entry. See complete history


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

Bisson, C.Adams, N.B.P.Stevenson, B.Brindley, A.A.Polyviou, D.Bibby, T.S.Baker, P.J.Hunter, C.N.Hitchcock, A.

(2017) Nat Commun 8: 1746-1746

  • DOI: https://doi.org/10.1038/s41467-017-01226-8
  • Primary Citation of Related Structures:  
    5JVB, 5LQ1, 5LQ5, 5LQ8, 5LV1, 5ME4, 5O2J, 5O2K, 5O37

  • PubMed Abstract: 

    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.

  • Organizational Affiliation

    Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, UK.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Phosphonate ABC transporter, periplasmic phosphonate-binding protein
A, B
280Trichodesmium erythraeum IMS101Mutation(s): 0 
Gene Names: Tery_0366
Find proteins for Q119I9 (Trichodesmium erythraeum (strain IMS101))
Explore Q119I9 
Go to UniProtKB:  Q119I9
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ119I9
Sequence Annotations
  • Reference Sequence
Small Molecules
Binding Affinity Annotations 
IDSourceBinding Affinity
2PO Binding MOAD:  5JVB Kd: 170 (nM) from 1 assay(s)
Experimental Data & Validation

Experimental Data

  • Resolution: 1.95 Å
  • R-Value Free: 0.267 
  • R-Value Work: 0.215 
  • R-Value Observed: 0.218 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 54.34α = 90
b = 69.31β = 93.07
c = 66.53γ = 90
Software Package:
Software NamePurpose
XDSdata reduction
Aimlessdata scaling
BUCCANEERmodel building

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2017-11-29
    Type: Initial release
  • Version 1.1: 2017-12-06
    Changes: Database references
  • Version 1.2: 2024-01-10
    Changes: Data collection, Database references, Refinement description