A sequence-specific function for the N-terminal signal-like sequence of the TonB protein

Mol Microbiol. 1993 Apr;8(2):379-88. doi: 10.1111/j.1365-2958.1993.tb01581.x.


TonB is a proline-rich protein which provides a functional link between the inner and outer membranes of Gram-negative bacteria. TonB is anchored to the inner membrane via an N-terminal signal-like sequence and spans the periplasm, interacting with transport receptors in the outer membrane. We have investigated the role of the N-terminal signal-like peptide in TonB function. Replacement of the N-terminal sequence with heterologous sequences indicates that it has at least three distinct roles in TonB function: (i) to facilitate translocation of TonB across the cytoplasmic membrane; (ii) to anchor TonB to the cytoplasmic membrane; (iii) a sequence-specific functional interaction with the ExbBD proteins.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism*
  • Biological Transport
  • Consensus Sequence
  • Escherichia coli / metabolism*
  • Escherichia coli Proteins*
  • Gram-Negative Bacteria / metabolism
  • Membrane Proteins / chemistry
  • Membrane Proteins / metabolism*
  • Molecular Sequence Data
  • Protein Sorting Signals / chemistry
  • Sequence Alignment
  • Sequence Homology, Amino Acid


  • Bacterial Proteins
  • Escherichia coli Proteins
  • ExbB protein, E coli
  • Membrane Proteins
  • Protein Sorting Signals
  • tolA protein, E coli
  • tonB protein, Bacteria
  • tonB protein, E coli
  • tolQ protein, E coli
  • exbD protein, E coli