TonB-dependent receptors - Structural perspectives

Andrew D. Ferguson, Johann Deisenhofer

Research output: Contribution to journalReview article

98 Scopus citations

Abstract

Plants, bacteria, fungi, and yeast utilize organic iron chelators (siderophores) to establish commensal and pathogenic relationships with hosts and to survive as free-living organisms. In Gram-negative bacteria, transport of siderophores into the periplasm is mediated by TonB-dependent receptors. A complex of three membrane-spanning proteins TonB, ExbB and ExbD couples the chemiosmotic potential of the cytoplasmic membrane with siderophore uptake across the outer membrane. The crystallographic structures of two TonB-dependent receptors (FhuA and FepA) have recently been determined. These outer membrane transporters show a novel fold consisting of two domains. A 22-stranded antiparallel β-barrel traverses the outer membrane and adjacent β-strands are connected by extracellular loops and periplasmic turns. Located inside the β-barrel is the plug domain, composed primarily of a mixed four-stranded β-sheet and a series of interspersed α-helices. Siderophore binding induces distinct local and allosteric transitions that establish the structural basis of signal transduction across the outer membrane and suggest a transport mechanism.

Original languageEnglish (US)
Pages (from-to)318-332
Number of pages15
JournalBiochimica et Biophysica Acta - Biomembranes
Volume1565
Issue number2
DOIs
StatePublished - Oct 11 2002

Keywords

  • Outer membrane protein
  • Siderophore
  • Signal transduction
  • TonB-dependent receptor
  • Transporter

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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