Specificity of unsaturated fatty acid-regulated expression of the Saccharomyces cerevisiae OLE1 gene.
The Saccharomyces cerevisiae OLE1 gene encodes the delta-9 fatty acid desaturase, an enzyme which forms the monounsaturated palmitoleic (16:1) and oleic (18:1) fatty acids from palmitoyl (16:0) or stearoyl (18:0) CoA. Previous studies demonstrated that OLE1 mRNA levels and desaturase enzyme activity are repressed when either 16:1 delta-9 and 18:1 delta-9 are added to the growth medium (1). The polyunsaturate, linoleic acid (18:2, delta-9,12), which is not a product of the enzyme, is also a strong repressor. The specificity of the OLE1 transcriptional regulatory sensor was examined by testing the response of OLE1 promoter-lacZ fusion reporter genes to fatty acids that differ in chain length, degree of unsaturation and double bond positions. Monounsaturated and polyunsaturated fatty acids that contain a delta-9 double bond are strong repressors of reporter gene activity and native OLE1 mRNA levels. Monounsaturated fatty acids containing double bonds in the delta-10, delta-11, or delta-5 positions showed no repression of reporter enzyme levels although they were rapidly incorporated into membrane lipids and some supported growth of an OLE1 gene disrupted strain. Although 17:1 delta-10 does not repress OLE1 transcription, lipid analysis showed that it replaces almost all of the endogenous 16:1 delta-9 and 18:1 delta-9 in cellular lipids and OLE1 mRNA levels are strongly repressed. This suggests that additional systems regulate desaturase activity by post-transcriptional mechanisms that differ from the transcriptional sensor in their responses to specific fatty acids.
McDonough
V M
VM
Bureau of Biological Research, Nelson Biological Laboratory, Rutgers University, Piscataway, New Jersey 08855-1059.
Stukey
J E
JE
Martin
C E
CE
D044943:Fatty Acid Desaturases / Q000096:biosynthesis / Q000235:genetics*; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects*; D005800:Genes, Fungal; D011401:Promoter Regions, Genetic; D012331:RNA, Fungal / Q000235:genetics / Q000302:isolation & purification; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D013230:Stearoyl-CoA Desaturase; D016385:TATA Box; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics
D005231:Fatty Acids, Unsaturated; D012331:RNA, Fungal; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D044943:Fatty Acid Desaturases; D013230:Stearoyl-CoA Desaturase; C029627:delta-9 fatty acid desaturase; D001616:beta-Galactosidase