Pseudomonas aeruginosa outer membrane permeability: isolation of a porin protein F-deficient mutant.
A mutant of Pseudomonas 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 beta-lactamase into the supernatant. Outer membrane permeability was measured in whole cells by examining the rates of hydrolysis of a chromogenic beta-lactam, nitrocefin, by periplasmic RP1-encoded beta-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.
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001435:Bacteriophages / Q000254:growth & development; D002463:Cell Membrane Permeability; D007473:Ion Channels; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D018272:Porins; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism*; D013499:Surface Properties
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D007473:Ion Channels; D008565:Membrane Proteins; D018272:Porins