Fatty acid alterations and polymyxin B binding by lipopolysaccharides from Pseudomonas aeruginosa adapted to polymyxin B resistance.
Lipopolysaccharides were extracted from freeze-dried cells of Pseudomonas aeruginosa PAO1 (polymyxin B susceptible), isolate A (polymyxin B resistant), and isolate A-reverted (polymyxin B intermediate resistance) by either the phenol-chloroform-petroleum ether or the modified phenol-water method. Isolate A and isolate A-reverted had drastic losses of 2-hydroxydodecanoic acid and significant decreases in 3-hydroxydecanoic acid. Concentrations of amide-linked 3-hydroxydecanoic acid were similar in all three strains. Minor alterations were noted in the composition of 3-deoxy-D-manno-2-octulosonic acid, heptose, phosphate, neutral sugars, and amino compounds. The concentrations of rhamnose in isolate A and of rhamnose and glucose in isolate A-reverted were significantly different from those in PAO1. Trace amounts of mannose and other minor unidentified carbohydrates were detected in all strains. Polymyxin B included in isolate. A growth medium complexed with lipopolysaccharides and remained bound throughout purification. PAO1 lipopolysaccharides bound more polymyxin B than did isolate A lipopolysaccharides. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated minor differences in smooth- and rough-form lipopolysaccharides of the different strains. We propose that loss of hydroxy fatty acids from lipopolysaccharides perturbs outer membrane hydrophobicity and is a contributing factor to polymyxin B adaptive resistance.
Conrad
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Department of Preclinical Education, College of Osteopathic Medicine, Oklahoma State University, Tulsa 74107.
Galanos
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C
D004352:Drug Resistance, Microbial; D004591:Electrophoresis, Polyacrylamide Gel; D005227:Fatty Acids / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D011112:Polymyxin B / Q000378:metabolism* / Q000494:pharmacology; D011113:Polymyxins / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000254:growth & development / Q000378:metabolism*
D005227:Fatty Acids; D008070:Lipopolysaccharides; D011113:Polymyxins; D011112:Polymyxin B