Identification of a Peroxisomal ATP Carrier Required for Medium-Chain Fatty Acid β-Oxidation and Normal Peroxisome Proliferation in Saccharomyces cerevisiae

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Abstract
We have characterized the role of YPR128cp, the orthologue of human PMP34, in fatty acid metabolism and peroxisomal proliferation inSaccharomyces cerevisiae. YPR128cp belongs to the mitochondrial carrier family (MCF) of solute transporters and is localized in the peroxisomal membrane. Disruption of theYPR128c gene results in impaired growth of the yeast with the medium-chain fatty acid (MCFA) laurate as a single carbon source, whereas normal growth was observed with the long-chain fatty acid (LCFA) oleate. MCFA but not LCFA β-oxidation activity was markedly reduced in intact ypr128cΔ mutant cells compared to intact wild-type cells, but comparable activities were found in the corresponding lysates. These results imply that a transport step specific for MCFA β-oxidation is impaired in ypr128cΔ cells. Since MCFA β-oxidation in peroxisomes requires both ATP and CoASH for activation of the MCFAs into their corresponding coenzyme A esters, we studied whether YPR128cp is an ATP carrier. For this purpose we have used firefly luciferase targeted to peroxisomes to measure ATP consumption inside peroxisomes. We show that peroxisomal luciferase activity was strongly reduced in intact ypr128cΔ mutant cells compared to wild-type cells but comparable in lysates of both cell strains. We conclude that YPR128cp most likely mediates the transport of ATP across the peroxisomal membrane.

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