TRANSPORT OF ACTIVATED FATTY-ACIDS BY THE PEROXISOMAL ATP-BINDING-CASSETTE TRANSPORTER PXA2 IN A SEMIINTACT YEAST-CELL SYSTEM

In the yeast Saccharomyces cerevisiae, fatty acid beta-oxidation is re stricted to peroxisomes. Previous studies have shown two possible rout es by which fatty acids enter the peroxisome. The first route involves transport of medium-chain fatty acids across the peroxisomal membrane as free fatty acids, followed by activation within the peroxisome by Faa2p, an acyl-CoA synthetase. The second route involves transport of long-chain fatty acids. Long-chain fatty acids enter the peroxisome vi a a route that involves activation in the extraperoxisomal space, foll owed by transport across the peroxisomal membrane. It has been suggest ed that this transport is dependent upon the peroxisomal ATP-binding-c assette transporters Pxa1p and Pxa2p. In this paper we investigated wh ether Pxa2p is directly responsible for the transport of C18:1-CoA, a long-chain acyl-CoA ester. Using protoplasts in which the plasma membr ane has been selectively permeabilised by digitonin, we show that C18: 1-CoA, but not C8:0-CoA, enters the peroxisome via Pxa2p, in an ATP-de pendent fashion. The results obtained may contribute to the elucidatio n of the primary defect in the human disease X-linked adrenoleukodystr ophy.