Identification of the protein producing transmembrane diffusion pores in the outer membrane of Pseudomonas aeruginosa PA01

Robert E.W. Hancock, Gary M. Decad, Hiroshi Nikaido

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The outer membrane of Pseudomonas aeruginosa PA01 is permeable to saccharides of molecular weights lower than about 6000. Triton X-100/EDTA-soluble outer membrane proteins were fractionated by ion-exchange chromatography in the presence of Triton X-100 and EDTA, and the protein contents of the various fractions analysed by sodium dodecyl sulphate polyacrylamide gel electrophoresis. Each of the major protein bands present in the Triton X-100/EDTA soluble outer membrane was separated from one another. Adjacent fractions were pooled, concentrated and extensively dialyzed to reduce the Triton X-100 concentration. Vesicles were reconstituted from lipopolysaccharide, phospholipids and each of these dialyzed fractions, and examined for their ability to retain [14C]sucrose. Control experiments indicated that the residual levels of Triton X-100 remaining in the dialyzed fractions had no effect on the formation or permeability to saccharides of the reconstituted vesicles. It was concluded that a major outer membrane polypeptide with an apparent weight of 35 000 is a porin, responsible for the size-dependent permeability of the outer membrane.

Original languageEnglish
Pages (from-to)323-331
Number of pages9
JournalBBA - Biomembranes
Issue number2
Publication statusPublished - 5 Jul 1979


  • (Pseudomonas aeruginosa, Outer membrane)
  • Membrane protein
  • Permeability
  • Porin
  • Reconstitution

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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