Pseudomonas aeruginosa outer membrane permeability: Isolation of a porin protein F-deficient mutant

T. I. Nicas, Robert Hancock

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A mutant of P. aeruginosa severely deficient in outer membrane protein F levels was isolated by screening heavily mutagenized strains for membrane protein alterations on sodium dodecyl sulphate-polyacrylamide gel electrophoresis. To provide a basis for phenotypic comparison, three independent spontaneous revertants with normal protein F levels were isolated. Neither the protein F-deficient mutant nor its revertants had gross surface alterations as judged by their sensitivities to 31 phages with diverse receptors and their low degrees of leakage of periplasmic β-lactamase into the supernatant. Outer membrane permeability was measured in whole cells by examining the rates of hydrolysis of a chromogenic β-lactam, nitrocefin, by periplasmic RP1-encoded β-lactamase. It was found that the outer membrane permeabilities of wild-type and protein F revertant strains were similar, but low when compared with those of Escherichia coli and an antibiotic-supersusceptible mutant Z61 of P. aeruginosa. The loss of protein F caused a further significant decrease in outer membrane permeability. The results suggest that protein F is a pore-forming protein in vivo and that only a small proportion, as few as 1 in 400, of the protein F molecules form active functional channels in vivo.

Original languageEnglish
Pages (from-to)281-285
Number of pages5
JournalJournal of bacteriology
Issue number1
Publication statusPublished - 1 Jan 1983
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

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