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Outer membranes of Gram‐negative bacteria are permeable to steroid probes
Author(s) -
Plésiat Patrick,
Nikaido Hiroshi
Publication year - 1992
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1992.tb00853.x
Subject(s) - biology , bacterial outer membrane , membrane , acinetobacter calcoaceticus , escherichia coli , comamonas testosteroni , lipopolysaccharide , biochemistry , lipid bilayer , gram negative bacteria , microbiology and biotechnology , biophysics , acinetobacter , enzyme , antibiotics , gene , endocrinology
Summary The permeability of bacterial outer membranes was assayed by coupling the influx of highly hydrophobic probes, 3‐oxosteroids, with their subsequent oxidation catalysed by 3‐oxosteroid δ1‐dehydrogenase, expressed from a gene cloned from Pseudomonas testosteroni. In Salmonella typhimurium producing wild‐type lipopolysaccharide, the permeability coefficients for uncharged steroids were 0.45 to 1 × 10 ‐5 cm S ‐1 and the diffusion appeared to occur mainly through the lipid bilayer domains of the outer membrane. These rates are one or two magnitudes lower than that expected for their diffusion through the usual biological membranes. The permeation rates were markedly increased (up to 100 times) when the lipopolysaccharide leaflet was perturbed either by adding deacylpolymyxin or by introducing mutations leading to the production of deep rough lipopolysaccharides. An amphiphilic, negatively charged probe, testosterone hemisuccinate, penetrated much more slowly than the uncharged steroids. Study of various Gram‐negative species revealed that P. testosteroni, Pseudomonas acidovorans , and Acinetobacter calcoaceticus showed higher outer membrane permeability to steroid probes and higher susceptibility to hydrophobic agents such as fusidic acid, novobiocin and crystal violet relative to S. typhimurium and Escherichia coli.