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K Poole

Publications and source records attributed to K Poole.

5 recordsLinked to original sources
PubMed1991

Interaction of aminoglycosides with the outer membranes and purified lipopolysaccharide and OmpF porin of Escherichia coli.

The mechanism of uptake of aminoglycosides across the outer membrane of Escherichia coli was reevaluated. Porin-deficient mutants showed no alteration in gentamicin or kanamycin susceptibility. Furthermore, the influence of kanamycin on intrinsic tryptophan fluorescence of porin OmpF (Y. Kobayashi, and T. Nakae, Eur. J. Biochem. 151:231-236, 1985) was shown to be strongly influenced by protein concentration and EDTA. This led to the hypothesis that aminoglycoside-mediated increases and decreases in intrinsic tryptophan fluorescence were due to aggregation-disaggregation of OmpF mediated by interaction at a divalent cation binding site on OmpF. Gentamicin, kanamycin, and polymyxin B increased E. coli outer membrane permeability to the hydrophobic fluorescent compound 1-N-phenyl-naphthylamine (NPN) and the peptidoglycan-degrading enzyme lysozyme. Addition of Mg2+ blocked these permeabilizing activities. Furthermore, gentamicin and polymyxin B bound to Mg(2+)-binding sites on E. coli lipopolysaccharide, as determined in dansyl polymyxin displacement experiments. A polymyxin-resistant, lipopolysaccharide-altered pmr mutant of E. coli had a fourfold-lower MIC of gentamicin and kanamycin and was more poorly permeabilized to 1-N-phenylnaphthylamine than was its parent strain. These data were consistent with uptake of aminoglycosides across the E. coli outer membrane by the self-promoted uptake mechanism.

Anti-Bacterial Agents↗
PubMed1991

Pyochelin-mediated iron transport in Pseudomonas aeruginosa: involvement of a high-molecular-mass outer membrane protein.

An iron-regulated outer membrane protein of 75,000 daltons was strongly expressed following iron limitation of strains of Pseudomonas aeruginosa which fail to produce pyoverdine. A mutant nonderepressible for this protein (K372) was deficient in pyochelin-mediated iron transport at 150 nM FeCl3, consistent with a role for the 75-kDa protein in ferripyochelin transport. Moreover, ferripyochelin specifically protected the 75-kDa protein against trypsin digestion, supporting an interaction between ferripyochelin and the 75-kDa protein. Previous reports implicated a 14,000-dalton outer membrane protein as the receptor for ferripyochelin (P.A. Sokol and D.E. Woods, Infect. Immun. 40:665-669, 1983) and demonstrated that a mutant (FBP-28) expressing a defective 14-kDa outer membrane protein did not exhibit pyochelin-mediated iron transport (P.A. Sokol, J. Bacteriol. 169:3365-3368, 1987). Nonetheless, we were able to demonstrate (i) that FBP-28 was inducible for the 75-kDa protein under iron-limiting conditions and (ii) that concomitant with the induction of this protein in FBP-28, pyochelin-mediated iron uptake at 150 nM FeCl3 was observed. Interestingly, strain K372 did transport ferripyochelin at higher (750 nM) FeCl3 concentrations, suggesting that a second pyochelin-mediated iron transport system, perhaps involving the 14-kDa outer membrane protein identified previously, operates in P. aeruginosa.

Bacterial Outer Membrane Proteins↗
PubMed1991

Pyoverdine-mediated iron transport in Pseudomonas aeruginosa: involvement of a high-molecular-mass outer membrane protein.

Reduced expression of an iron-regulated outer membrane protein (IROMP) of approximate molecular mass 90,000 was observed in Pseudomonas aeruginosa concomitant with a loss of pyoverdine production in a wild type strain grown at 43 degrees C and in a mutant deficient in pyoverdine production. Consistent with an implied role in pyoverdine-mediated iron transport a mutant lacking the 90 kDa protein transported barely detectable levels of ferri-pyoverdine. Interestingly, the mutant still exhibited pyoverdine-dependent growth in an iron-deficient medium containing the synthetic iron chelator ethylene diamine-di(omicron-hydroxyphenol acetic acid) (EDDHA) suggesting that a second uptake system for ferri-pyoverdine may exist in P. aeruginosa.

Bacterial Outer Membrane Proteins↗