title: Conversion of phospholipids to free fatty acids in response to acquisition of polymyxin resistance in Pseudomonas aeruginosa.
abstract: The readily extractable lipids from a Pseudomonas aeruginosa isolate stepwise adapted to polymyxin resistance were compared with those of the susceptible parent and of a revertant strain which regained susceptibility. Significant qualitative and quantitative lipid alterations accompany the acquisition of resistance. Changes include the appearance of a major unidentified lipid (lipid X) unique to the readily extractable lipids of resistant cells. Comparative studies with parent and revertant strains indicated a significant decrease in the phospholipid content of resistant cells. Thin-layer chromatography of resistant-cell readily extractable lipids demonstrated: (i) the emergence of lipid X (36% of total readily extractable lipids), (ii) a decrease in phosphatidylethanolamine and phosphatidylglycerol, and (iii) an increase in diphosphatidylglycerol. Lipid X was purified by preparative silicic acid column chromatography and thin-layer chromatography and characterized by analytical thin-layer chromatography, column adsorption chromatography, and gas-liquid chromatography. Data from this study indicated that lipid X was a mixture of free fatty acids. The fatty acids present in lipid X were qualitatively and quantitatively the same as the fatty acids esterified to the phospholipids in the readily extractable lipids.
mesh_terms: D001711:Biotransformation; D004352:Drug Resistance, Microbial; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D050356:Lipid Metabolism; D010743:Phospholipids / Q000378:metabolism*; D011112:Polymyxin B / Q000494:pharmacology*; D011113:Polymyxins / Q000494:pharmacology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000378:metabolism*
chemical_list: D005230:Fatty Acids, Nonesterified; D010743:Phospholipids; D011113:Polymyxins; D011112:Polymyxin B