Regulation of Citrate Efflux from Mitochondria of Oleaginous and Non‐Oleaginous Yeass by Long‐Chain Fatty Acyl‐CoA Esters

Abstract

Citrate efflux from a wide range of yeast mitochondria was inhibited by long‐chain fatty‐acy1‐CoA esters. Fatty‐acy1‐CoA esters with chain lengths of between 14 and 18 carbonbs were the most potent inhibitors of citrate efflux which was unaffected by the fatty acids themeselves. 50% inhibiton of citrate transport was onserved using palmitoy1‐CoA at approx. 4–5 μM when the tricarboxylate carrier was saturated with l‐malate as counter‐anion. The inhibiton with palmitoy1‐CoA and oleoy1‐CoA was competitive with l‐malate. The possibility that the fatty‐CoA esers were exerting their effect by acting as detergent was wliminated 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 membrance damage. The effect of fatty‐CoA esters on citrate efflux could be decreased by udi9ng higher mitochondrial protein levels and by adding bovine serum albumin. The possiblity is discussed that this inhibition represents a genune feedback inhibition which could regulate the amount of lipid being synthesized by an oleaginous yeast. Copyright © 1983, Wiley Blackwell. All rights reserved