Structure of TonB in complex with FhuA, E. coli outer membrane receptor

Science. 2006 Jun 2;312(5778):1399-402. doi: 10.1126/science.1128057.


The cytoplasmic membrane protein TonB spans the periplasm of the Gram-negative bacterial cell envelope, contacts cognate outer membrane receptors, and facilitates siderophore transport. The outer membrane receptor FhuA from Escherichia coli mediates TonB-dependent import of ferrichrome. We report the 3.3 angstrom resolution crystal structure of the TonB carboxyl-terminal domain in complex with FhuA. TonB contacts stabilize FhuA's amino-terminal residues, including those of the consensus Ton box sequence that form an interprotein beta sheet with TonB through strand exchange. The highly conserved TonB residue arginine-166 is oriented to form multiple contacts with the FhuA cork, the globular domain enclosed by the beta barrel.

Publication types

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

MeSH terms

  • Bacterial Outer Membrane Proteins / chemistry*
  • Bacterial Outer Membrane Proteins / metabolism
  • Crystallography, X-Ray
  • Escherichia coli / chemistry*
  • Escherichia coli / metabolism
  • Escherichia coli Proteins / chemistry*
  • Escherichia coli Proteins / metabolism
  • Ferric Compounds / metabolism
  • Membrane Proteins / chemistry*
  • Membrane Proteins / metabolism
  • Models, Molecular
  • Protein Binding
  • Protein Conformation
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Surface Plasmon Resonance


  • Bacterial Outer Membrane Proteins
  • Escherichia coli Proteins
  • Ferric Compounds
  • FhuA protein, E coli
  • Membrane Proteins
  • tonB protein, E coli

Associated data

  • PDB/2GRX