Properties of the large ion-permeable pores formed from protein F of Pseudomonas aeruginosa in lipid bilayer membranes

Roland Benz, Robert E.W. Hancock

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The incorporation of porin protein F from the outer membrane of Pseudomonas aeruginosa into artificial lipid bilayers results in an increase of the membrane conductance by many orders of magnitude. The membrane conductance is caused by the formation of large ion-permeable channels with a single-channel conductance in the order of 5 nS for 1 M alkali chlorides. The conductance has an ohmic current vs. voltage relationship. Further information on the structure of the pore formed by protein F was obtained by determining the single-channel conductance for various species differing in charge and size, and from zero-current potential measurements. The channel was found to be permeable for large organic ions (Tris+, N(C2H5)4+, Hepes-) and a channel diameter of 2.2 nm could be estimated from the conductance data (pore length of 7.5 nm). At neutral pH the pore is about two times more permeable for cations than for anions, possibly caused by negative charges in the pore. The consistent observation of large water filled pores formed by porin protein F in model membrane systems is discussed in the light of the known low permeability of the Ps. aeruginosa outer membrane towards antibiotics. It is suggested that this results from a relatively low proportion of open functional porin protein F pores in vivo.

Original languageEnglish
Pages (from-to)298-308
Number of pages11
JournalBBA - Biomembranes
Issue number2
Publication statusPublished or Issued - 20 Aug 1981


  • (Ps. aeruginosa)
  • Lipid bilayer
  • Outer membrane
  • Pore formation
  • Porin
  • Selectivity

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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