Regulation of citrate efflux from mitochondria of oleaginous and non-oleaginous yeasts by long-chain fatty acyl-CoA esters.
1. Citrate efflux from a wide range of yeast mitochondria was inhibited by long-chain fatty-acyl-CoA esters. 2. Fatty-acyl-CoA esters with chain lengths of between 14 and 18 carbons were the most potent inhibitors of citrate efflux which was unaffected by the fatty acids themselves. 3. 50% inhibition of citrate transport was observed using palmitoyl-CoA and oleoyl-CoA at approx. 4-5 microM when the tricarboxylate carrier was saturated with L-malate as counter-anion. 4. The inhibition with palmitoyl-CoA and oleoyl-CoA was competitive with L-malate. 5. The possibility that the fatty-acyl-CoA esters were exerting their effect by acting as detergent was eliminated because of the low concentrations used and appropriate comparisons being made with non-specific detergents. Although detergents inhibited citrate efflux they also released citrate by causing membrane damage. 6. The effect of fatty-acyl-CoA esters on citrate efflux could be decreased by using higher mitochondrial protein levels and by adding bovine serum albumin. 7. The possibility is discussed that this inhibition represents a genuine feedback inhibition which could regulate the amount of lipid being synthesized by an oleaginous yeast.
D000214:Acyl Coenzyme A / Q000494:pharmacology*; D001692:Biological Transport / Q000187:drug effects; D002175:Candida / Q000378:metabolism; D002951:Citrates / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D015003:Yeasts / Q000187:drug effects / Q000378:metabolism*
D000214:Acyl Coenzyme A; D002951:Citrates