Disruption of a yeast very-long-chain acyl-CoA synthetase gene simulates the cellular phenotype of X-linked adrenoleukodystrophy
X-linked adrenoleukodystrophy (X-ALD) is characterized biochemically by elevated levels of saturated very long-chain fatty acids (VLCFAs) in plasma and tissues. In X-ALD, peroxisomal very-long-chain acyl-CoA synthetase (VLCS) fails to activate VLCFAs, preventing their degradation via β-oxidation. However, the product of the defective XALD gene (ALDP) is not a VLCS, but rather a peroxisomal membrane protein (PMP). Disruption of either or both of two yeast PMP genes related to the XALD gene did not produce a biochemical phenotype resembling that found in X-ALD fibroblasts. The authors identified a candidate yeast VLCS gene (the FAT1 locus) by its homology to rat liver VLCS. Disruption of this gene decreased VLCS activity, but had no effect on long-chain acyl-CoA synthetase activity. In FAT1-disruption strains, VLCS activity was reduced to 30–40% of wild-type in both a microsome-rich 27,000g supernatant fraction and a peroxisome- and mitochondria-rich pellet fraction of yeast spheroplast homogenates. Separation of the latter organelles by density gradient centrifugation revealed that VLCS activity was peroxisomal and not mitochondrial. VLCS gene-disruption strains had increased cellular VLCFA levels, compared to wild-type yeast. The extent of both the decrease in peroxisomal VLCS activity and the VLCFA accumulation in this yeast model resembles that observed in cells from X-ALD patients. Characterization of the gene(s) responsible for the residual peroxisomal VLCS activity may suggest new therapeutic approaches in X-ALD.
Index EntriesPeroxisomes yeast Saccharomyces cerevisiae very-long chain fatty acids (VLCFAs) very-long chain acyl-CoA synthetase (VLCS) X-linked adrenoleukodystrophy (X-ALD)
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- 1.Moser, H. W., Smith, K. D., and Moser, A. B. (1995) X-linked adrenoleukodystrophy, in The Metabolic and Molecular Bases of Inherited Disease (Scriver, C. R., Beaudet, R. L., Sly, W. S., and Valle, D., eds.), McGraw-Hill, New York, pp. 2325–2349.Google Scholar
- 2.Wanders, R. J. A., van Roermund, C. W. T., van Wijland, M. J. A., Schutgens, R. B. H., van den Bosch, H., Schram, A. W., and Tager, J. M. (1988) Direct demonstration that deficient oxidation of very long chain fatty acids in X-linked adrenoleukodystrophy is due to an impaired ability of peroxisomes to activate very long chain fatty acids. Biochem. Biophys. Res. Commun. 153, 618–624.PubMedCrossRefGoogle Scholar
- 4.Uchida, Y., Kondo, N., Orii, T., and Hashimoto, T. (1996) Purification and properties of rat liver peroxisomal very-long-chain acyl-CoA synthetase. J. Biochem. (Tokyo) 119, 565–571.Google Scholar
- 5.Uchiyama, A., Aoyama, T., Kamijo, K., Uchida, Y., Kondo, M., Orii, T., and Hashimoto, T. (1996) Molecular cloning of cDNA encoding rat very long-chain acyl-CoA synthetase. J. Biol. Chem. 271, 30,360–30,365.Google Scholar
- 7.Crane, D. I., Kalish, J. E., and Gould, S. J. (1994) Pichia pastoris PAS4 gene encodes a ubiquitin-conjugating enzyme required for peroxisome assembly. J. Biol. Chem. 269, 21,835–21,844.Google Scholar
- 9.Moser, H. W., and Moser, A. B. (1991) Measurements of saturated very long chain fatty acids in plasma, in Techniques in Diagnostic Human Biochemical Genetics (Hommes, F., ed.), Wiley-Liss, New York, pp. 177–191.Google Scholar
- 14.Hettema, E. H., van Roermund, C. W. T., Distel, B., van den Berg, M., Vilela, C., Rodrigues-Pousada, C., Wanders, R. J. A., and Tabak, H. F. (1996) The ABS transporter proteins Pat1 and Pat2 are required for import of long-chain fatty acids into peroxisomes of Saccharomyces cerevisiae. EMBO J 15, 3813–3822.PubMedGoogle Scholar
- 15.Knoll, L. J., Johnson, D. R., and Gordon, J. I. (1994) Biochemical studies of three Saccharomyces cerevisiae acyl-CoA synthetases, Faa1p, Faa2p, and Faa3p. J. Biol. Chem. 269, 16,348–16,356.Google Scholar