Identification of Peroxisomal Acyl-CoA Thioesterases in Yeast and Humans*
- From the Departments of ‡Biological Chemistry and¶Pediatrics, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205 and the §Department of Physiological Chemistry, Ruhr-Universitat Bochum, 44780 Bochum, Germany
Abstract
A computer-based screen of theSaccharomyces cerevisiae genome identifiedYJR019C as a candidate oleate-induced gene.YJR019C mRNA levels were increased significantly during growth on fatty acids, suggesting that it may play a role in fatty acid metabolism. The YJR019C product is highly similar to tesB, a bacterial acyl-CoA thioesterase, and carries a tripeptide sequence, alanine-lysine-phenylalanineCOOH, that closely resembles the consensus sequence for type-1 peroxisomal targeting signals. YJR019C directed green fluorescence protein to peroxisomes, and biochemical studies revealed that YJR019C is an abundant component of purified yeast peroxisomes. Disruption of the YJR019C gene caused a significant decrease in total cellular thioesterase activity, and recombinant YJR019C was found to exhibit intrinsic acyl-CoA thioesterase activity of 6 units/mg. YJR019C also shared significant sequence similarity with hTE, a human thioesterase that was previously identified because of its interaction with human immunodeficiency virus-Nef in the yeast two-hybrid assay. We report here that hTE is also a peroxisomal protein, demonstrating that thioesterase activity is a conserved feature of peroxisomes. We propose that YJR019Cand hTE be renamed as yeast and human PTE1 to reflect the fact that they encode peroxisomal thioesterases. The physical segregation of yeast and human PTE1 from the cytosolic fatty acid synthase suggests that these enzymes are unlikely to play a role in formation of fatty acids. Instead, the observation that PTE1 contributes to growth on fatty acids implicates this thioesterase in fatty acid oxidation.
Footnotes
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↵* This work was supported in part by National Institutes of Health Grant DK45787 (to S. J. G.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) AFI24264 and AFI24265.
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↵‖ To whom correspondence should be addressed: Dept. of Biological Chemistry, The Johns Hopkins University School of Medicine, 725 N. Wolfe St., Baltimore, MD 21205. Tel.: 410-955-3085; Fax: 410-955-0215; E-mail: Stephen.Gould{at}qmail.bs.jhu.edu.
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↵2 M. T. Geraghty, D. Bassett, J. C. Morrell, G. J. Gatto, Jr., J. Bai, B. V. Geisbrecht, P. Hieter, and S. J. Gould, submitted for publication.
- Abbreviations:
- ORF
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open reading frame
- PCR
-
polymerase chain reaction
- GFP
-
green fluorescent protein
- MBP
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maltose-binding protein
- HPLC
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high performance liquid chromatography
- PAGE
-
polyacrylamide gel electrophoresis
- HIV
-
human immunodeficiency virus
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- Received September 28, 1998.
- Revision received December 22, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
