Nutritional regulation of yeast delta-9 fatty acid desaturase activity

• Published in: Journal of Bacteriology 1989-12, Vol.171 (12), p.6409-6413
• Main Authors: BOSSIE, M. A, MARTIN, C. E
• Format: Article
• Language: English
• Subjects: acide gras; acidos grasos; actividad enzimatica; activite enzymatique; Biological and medical sciences; Blotting, Northern; culture media; cytoplasmic organelles; enzymic activity; Fatty Acid Desaturases - genetics; Fatty Acid Desaturases - metabolism; fatty acids; Fatty Acids, Unsaturated - metabolism; Fatty Acids, Unsaturated - pharmacology; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Fungal; Genes, Fungal; Growth, nutrition, metabolism, transports, enzymes. Molecular biology; medio de cultivo; Microbiology; Microsomes - enzymology; milieu de culture; Mycology; organite cellulaire; organulos citoplasmaticos; oxidoreductases; oxidorreductasas; oxydoreductase; RNA, Fungal - genetics; RNA, Fungal - isolation & purification; RNA, Messenger - genetics; RNA, Messenger - isolation & purification; saccharomyces cerevisiae; Saccharomyces cerevisiae - drug effects; Saccharomyces cerevisiae - enzymology; Saccharomyces cerevisiae - growth & development; Stearoyl-CoA Desaturase; Structure-Activity Relationship
• ISSN: 0021-9193; 1098-5530; 1067-8832
• DOI: 10.1128/jb.171.12.6409-6413.1989

The addition of unsaturated fatty acids to cultures of Saccharomyces cerevisiae significantly altered the microsomal lipid composition. Supplementation with either of the naturally occurring palmitoleic (16:1) or oleic (18:1) acids caused increased levels in membrane phospholipids and reduced levels of the complementary acid. Growth in the presence of equimolar quantities of 16:1 and 18:1 acids, however, produced a fatty acid composition similar to that found in unsupplemented cell membranes. Linoleic acid (18:2) was not found in S. cerevisiae grown under normal conditions. It was preferentially internalized and incorporated into microsomes, however, at levels exceeding 50% of the total fatty acid species. This resulted in an almost total loss of 16:1 and a reduction of 18:1 to 25% of its normal level. The delta-9 fatty acid desaturase, a microsomal enzyme that forms 16:1 and 18:1 from saturated acyl coenzyme A precursors, was affected by the presence of exogenous fatty, acids. Enzyme activity toward the 16:0 coenzyme A substrate was elevated in microsomes from saturated-fatty-acid-supplemented cultures and sharply repressed following the addition of unsaturated fatty acids, including 18:2. Northern (RNA blot) and slot-blot analyses of mRNA encoded by the OLE1 gene, which appears to be the structural gene for the delta-9 desaturase, indicated that it was sharply reduced in unsaturated-fatty-acid-fed cells. These data suggest that a significant part of the regulation involves modulation of available transcripts.