PXA1, a putative S. cerevisiae homolog of the human adrenoleukyodystrophy gene
- Johns Hopkins Univ. School of Medicine, Baltimore, MD (United States)
The adrenoleukodystrophy protein (ALDP) and the 70 kD peroxisomal membrane protein (PMP70) are ATP-binding cassette transporters in the peroxisome membrane. The former is defective in X-linked adrenoleukodystrophy (ALD), a neurodegenerative disorder with defective peroxisome oxidation of very long chain fatty acids; the latter is implicated in Zellweger syndrome, a defect in peroxisome biogenesis. The functions and interactions of ALDP and PMP70 in the peroxisomal membrane are not known. To develop a system in which these questions could be addressed, we sought to clone their yeast homologs. Using RT/PCR with degenerate primers and oleic acid (C18:1) induced yeast RNA as template, we amplified a cDNA segment corresponding to a conserved region of ALDP and PMP70. By sequencing amplified products, we found one with homology to both proteins and used it to clone the corresponding full length yeast gene (PXA1). PXA1 encodes a 758 amino acid protein with 28% and 21% overall identity to ALDP and PMP70, respectively which increases to 47% and 39% in a C terminal region of 178 amino acids. The PXA1 protein precipitates with peroxisomes as shown by immunoblot analysis of cell fractionation gradients. Disruption of PXA1 by homologous recombination results in impaired growth on oleic acid and reduced ability to oxidize oleate. The growth phenotype can be corrected by expression of the wild type PXA1 in the mutant strain. Peroxisomes in the PXA1 mutant yeast strain are intact as judged by catalase distribution and electron microscopy. Given the amino acid similarity, fatty acid oxidation defect and lack of an effect on peroxisomal integrity, we hypothesize that PXA1 may be the yeast ortholog of ALDP. Complementation studies to examine this hypothesis are in progress.
- OSTI ID:
- 133872
- Report Number(s):
- CONF-941009-; ISSN 0002-9297; TRN: 95:005313-0606
- Journal Information:
- American Journal of Human Genetics, Vol. 55, Issue Suppl.3; Conference: 44. annual meeting of the American Society of Human Genetics, Montreal (Canada), 18-22 Oct 1994; Other Information: PBD: Sep 1994
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BASIC STUDIES
GENES
STRUCTURE-ACTIVITY RELATIONSHIPS
GENE MUTATIONS
DNA-CLONING
NERVOUS SYSTEM DISEASES
BIOLOGICAL MODELS
PROTEINS
SACCHAROMYCES CEREVISIAE
COMPARATIVE EVALUATIONS
HUMAN POPULATIONS
HEREDITARY DISEASES
DNA SEQUENCING
POLYMERASE CHAIN REACTION
AMINO ACIDS
GENE RECOMBINATION
OXIDATION
HUMAN X CHROMOSOME