Volume 20, Issue 4 p. A99-A99
Biochemistry (American Society for Biochemistry and Molecular Biology)
Free Access

Beta oxidation of oleic acid in yeast requires a thioesterase but not dienoyl-CoA isomerase

Andre G. Ntamack

Andre G. Ntamack

Chemistry, City College and Graduate School of CUNY, Convent Avenue at 138th Street, New York, NY, 10031

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Igor V. Karpichev

Igor V. Karpichev

Chemistry, City College and Graduate School of CUNY, Convent Avenue at 138th Street, New York, NY, 10031

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Gillian M. Small

Gillian M. Small

Chemistry, City College and Graduate School of CUNY, Convent Avenue at 138th Street, New York, NY, 10031

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Horst Schulz

Horst Schulz

Chemistry, City College and Graduate School of CUNY, Convent Avenue at 138th Street, New York, NY, 10031

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First published: 06 March 2006

Abstract

The β-oxidation of unsaturated fatty acids in yeast was studied by measuring and comparing the growth of wild-type S. cerevisiae with the growth of mutants that either have a deleted Δ3,5, Δ2,4-dienoyl-CoA isomerase (dienoyl-CoA isomerase) gene (DCI1) or thioesterase gene (TES1) on oleic or palmitic acid. Growth of wild-type and dci1 strains on oleic acid was indistinguishable, whereas the tes1 mutant grew slower and to a lower density. In contrast, all three strains grew in a similar manner on palmitic acid. 3,5-Tetradecanoic acid was detected in the medium by gas chromatography/mass spectrometry after growth of wild-type cells on oleic acid but not when palmitic acid was the carbon source. When the tes1 mutant was transformed with a plasmid expressing human dienoyl-CoA isomerase, the growth defect on oleic acid was partially corrected. These observations support the conclusion that the product of the DCI1 gene does not function as dienoyl-CoA isomerase in oleate β-oxidation. Hence 3,5-tetradecadienoyl-CoA, an intermediate of oleate β-oxidation, does not seem to be degraded via the reductase-dependent pathway but rather by an alternate pathway that involves a thioesterase, which hydrolyzes 3,5-tetradecadienoyl-CoA to 3,5-tetradecadienoic acid that is excreted into the growth medium.

(Supported by NIH Grants GM08168 and RR03060 and Grant 0350364N from the American Heart Association).