Modulation of fatty acid incorporation and desaturation by trifluoperazine in fungi.

The effects of trifluoperazine (TFP) on [1-(14)C]fatty acid incorporation into the lipids ofMortierella ramanniana var.angulispora were studied. TFP decreased [1-(14)C]-fatty acid incorporation into phosphatidylcholine, phosphatidylethanolamine and triacylglycerol, but greatly increased(14)C-labeling in phosphatidic acid. These changes in [1-(14)C]fatty acid incorporation induced by TFP were accompanied by a decrease in desaturation of some [1-(14)C]fatty acids taken up by the fungal cells. When [1-(14)C]lioleic acid (LA) was incubated with the fungal cells, total γ-linolenic acid (GLA) formation from incorporated [1-(14)C]LA decreased, but the(14)C-labeled GLA conent in individual lipid classes was essentially unchanged. This suggests that the site of the TFP effect on GLA formation from [1-(14)C]LA taken up from the medium is not the desaturase acting on LA linked to complex lipids. On the other hand, GLA formation from [1-(14)C]oleic acid was much less susceptile to TFP, which suggests that in this fungus Δ6 desaturation to GLA has at least two different pathways with different degrees of susceptibility to TFP.