Uptake of fatty acids by Mycoplasma capricolum

The energy requirements for fatty acid uptake by Mycoplasma capricolum were studied. Fatty acid transport and esterification to phospholipid appeared to be tightly coupled, since there was little intracellular accumulation of free fatty acid. Uptake was blocked by iodoacetate, n-ethylmaleimide, and p-chloromercuribenzoate. Glucose, glycerol, and potassium ions were necessary for fatty acid uptake by whole cells. A reduction in uptake was observed in cells treated with valinomycin or dicyclohexylcarbodiimide. The effect of temperature on the rate of oleate uptake showed a discontinuity at 24 degrees C. Above 24 degrees C an energy of activation of 4.6 kcal (ca. 19.2 kJ)/mol was obtained. The data suggest that uptake of fatty acid by M. capricolum is an energy-linked, protein-mediated process. A membrane-bound enzyme activity that catalyzed the synthesis of fatty acyl-hydroxamate was demonstrated. This activity was virtually independent or only marginally dependent on coenzyme A, depending on the assay system, but was stimulated approximately twofold by ATP.