The plug domain of a neisserial TonB-dependent transporter retains structural integrity in the absence of its transmembrane β-barrel

M. Oke, R. Sarra, R. Ghirlando, S. Farnaud, A. R. Gorringe, R. W. Evans, S. K. Buchanan

Research output: Contribution to journalArticle

15 Citations (Scopus)


Transferrin binding protein A (TbpA) is a TonB-dependent outer membrane protein expressed by pathogenic bacteria for iron acquisition from human transferrin. The N-terminal 160 residues (plug domain) of TbpA were overexpressed in both the periplasm and cytoplasm of Escherichia coli. We found this domain to be soluble and monodisperse in solution, exhibiting secondary structure elements found in plug domains of structurally characterized TonB-dependent transporters. Although the TbpA plug domain is apparently correctly folded, we were not able to observe an interaction with human transferrin by isothermal titration calorimetry or nitrocellulose binding assays. These experiments suggest that the plug domain may fold independently of the β-barrel, but extracellular loops of the β-barrel are required for ligand binding.

Original languageEnglish
Pages (from-to)294-300
Number of pages7
JournalFEBS Letters
Issue number3
Publication statusPublished - 30 Apr 2004
Externally publishedYes



  • HRP, horseradish peroxidase
  • hTf, human transferrin
  • Human transferrin
  • Iron transport
  • Neisseria meningitidis
  • PBS, phosphate-buffered saline
  • TbpA, transferrin binding protein A
  • TbpB, transferrin binding protein B
  • TonB
  • Transferrin binding protein A

ASJC Scopus subject areas

  • Structural Biology
  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology

Cite this