Voltage-gating of Escherichia coli porin: a cystine-scanning mutagenesis study of loop 3

J Mol Biol. 1998 Jan 16;275(2):171-6. doi: 10.1006/jmbi.1997.1474.


Porins, such as Escherichia coli OmpF, provide the only reported example of a voltage-gated channel where the three-dimensional structure is known to high resolution. Mutations that affect voltage-gating are clustered around the eyelet region, which is a mid-channel constriction caused by a polypeptide loop (L3) folding inside the lumen of this beta-barrel pore. These data, combined with molecular dynamics simulations, indicate that voltage-gating may involve L3 displacement. We have constructed six double cysteine OmpF mutants, five of which form disulphide bonds fixing L3 in the conformation determined by X-ray crystallography. These channels have altered single-channel conductances but unimpaired voltage-gating. The data show that L3 movement is not required for voltage-gating.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Amino Acid Substitution
  • Cystine*
  • Disulfides
  • Escherichia coli / physiology*
  • Ion Channel Gating*
  • Lipid Bilayers
  • Models, Molecular
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Porins / chemistry*
  • Porins / metabolism
  • Protein Conformation*
  • Recombinant Proteins / chemistry


  • Disulfides
  • Lipid Bilayers
  • OmpF protein
  • Porins
  • Recombinant Proteins
  • Cystine