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Gene Review

OLE1  -  stearoyl-CoA 9-desaturase

Saccharomyces cerevisiae S288c

Synonyms: Acyl-CoA desaturase 1, Fatty acid desaturase 1, Stearoyl-CoA desaturase 1, YGL055W
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Disease relevance of OLE1

  • To define the possible roles of each of these genes on hypoxia-induced OLE1 expression, we examined OLE1 expression under normoxia, hypoxia, and cobalt treatment conditions in Deltamga2 or Deltaspt23 deletion strains [1].
  • Mutation of host delta9 fatty acid desaturase inhibits brome mosaic virus RNA replication between template recognition and RNA synthesis [2].
  • Recent findings on the structure and expression of different types of fatty acid desaturase in cyanobacteria, plants and animals are reviewed in this article [3].

High impact information on OLE1

  • The OLE pathway of yeast regulates the level of the ER-bound enzyme Delta9-fatty acid desaturase OLE1, thereby controlling membrane fluidity [4].
  • We found that CDC48(UFD1/NPL4) plays a second role in the OLE pathway by mediating ERAD of OLE1 [5].
  • Here we report that the OLE1 protein itself is naturally short-lived and is degraded by ubiquitin/proteasome-dependent ER-associated degradation (ERAD) [5].
  • In addition, transition metals (Co and Ni) induce the expression of OLE1 and CYC7 in a concentration-dependent manner under aerobic conditions [6].
  • Fluorescence anisotropy of mitochondrial membranes of completed strains corresponded to the different activity of the Ole1 promoter used [7].

Biological context of OLE1

  • An analysis of mutants that are defective in mRNA degradation indicate that the Mga2p-requiring control mechanism that regulates the fatty acid-mediated instability of the OLE1 transcript acts by activating exosomal 3' --> 5'-exonuclease degradation activity [8].
  • A deletion analysis of OLE1 promoter::lacZ fusion reporter genes identified a 111-base pair (bp) fatty acid-regulated (FAR) region approximately 580 bp upstream of the start codon that is essential for transcription activation and unsaturated fatty acid repression [9].
  • The fatty acid repression of transcription under those conditions is attenuated by Spt23Deltatm, however, suggesting that the two proteins may interact to modulate OLE1 gene expression [10].
  • Regulatory elements that control transcription activation and unsaturated fatty acid-mediated repression of the Saccharomyces cerevisiae OLE1 gene [9].
  • By EMS mutagenesis, we isolated three classes of mutants, pfo1, pfo2 and pfo3 positive regulatory factor for OLE1) mutants, which show decreased rAPase activity under derepression conditions (absence of oleic acid) [11].

Anatomical context of OLE1


Associations of OLE1 with chemical compounds

  • Mga2p of Saccharomyces cerevisiae is an endoplasmic reticulum (ER)-localized transcription factor that plays an overlapping role with homologous Spt23p in upregulating expression of OLE1, a gene required for the synthesis of essential oleic acid [15].
  • Expressed alone, Mga2p induces high levels of OLE1 transcription in cells exposed to cobalt or grown in glycerol-containing medium [10].
  • We have found that carbon monoxide (CO) completely blocks the anoxia-induced expression of two hypoxic genes, OLE1 and CYC7, partially blocks the induction of a third gene, COX5b, and has no effect on the expression of other hypoxic or aerobic genes [6].
  • Inhibition of translation, by the addition of cycloheximide, slows the nucleolytic degradation of the OLE1 mRNA and blocks the unsaturated fatty acid-triggered reduction in its half-life [16].
  • Yeast adaptation to 2,4-dichlorophenoxyacetic acid involves increased membrane fatty acid saturation degree and decreased OLE1 transcription [17].

Regulatory relationships of OLE1

  • Spt23p expressed alone activates OLE1 transcription to levels similar to those in wild type cells [10].
  • These results suggested that ATF1 transcription was co-regulated by the same mechanism as the OLE1 gene and that unsaturated fatty acids and oxygen repressed the ATF1 transcript by a different regulation pathway [13].
  • A similar chimera under GAL1 control that replaces the OLE1 mRNA 5'-untranslated region with GAL1 sequences is not regulated by unsaturated fatty acids [16].
  • It exhibited Delta12 fatty acid desaturase activity when expressed in S. cerevisiae under the control of ADH1 promoter and produced endogenous linoleic acid [18].

Other interactions of OLE1

  • Mga2p appears to have two distinct functions with respect to the OLE1 mRNA stability: a stabilizing effect in cells grown in fatty acid-free medium and a destabilizing function in cells that are exposed to unsaturated fatty acids [8].
  • An analysis of spt23Delta and mga2Delta strains shows that Spt23p and Mga2p differentially activate and regulate OLE1 transcription [10].
  • These functions are independent of OLE1 transcription and can confer basal and regulated stability on OLE1 mRNAs that are produced under the control of the unrelated GAL1 promoter [8].
  • Two fatty acid activation genes, FAA1 and FAA4, were found to be essential for unsaturated fatty acid repression of OLE1 through the FAR sequences [9].
  • In addition, four other classes of mutants, nfo1, nfo2, nfo3 and nfo4 (negative factor for OLE1) mutants that have mutations causing strong expression of the OLE1p-PHO5 fusion gene under repression conditions (presence of oleic acid), were isolated [11].

Analytical, diagnostic and therapeutic context of OLE1


  1. MGA2 is involved in the low-oxygen response element-dependent hypoxic induction of genes in Saccharomyces cerevisiae. Jiang, Y., Vasconcelles, M.J., Wretzel, S., Light, A., Martin, C.E., Goldberg, M.A. Mol. Cell. Biol. (2001) [Pubmed]
  2. Mutation of host delta9 fatty acid desaturase inhibits brome mosaic virus RNA replication between template recognition and RNA synthesis. Lee, W.M., Ishikawa, M., Ahlquist, P. J. Virol. (2001) [Pubmed]
  3. Structure and expression of fatty acid desaturases. Los, D.A., Murata, N. Biochim. Biophys. Acta (1998) [Pubmed]
  4. Mobilization of processed, membrane-tethered SPT23 transcription factor by CDC48(UFD1/NPL4), a ubiquitin-selective chaperone. Rape, M., Hoppe, T., Gorr, I., Kalocay, M., Richly, H., Jentsch, S. Cell (2001) [Pubmed]
  5. Role of the ubiquitin-selective CDC48(UFD1/NPL4 )chaperone (segregase) in ERAD of OLE1 and other substrates. Braun, S., Matuschewski, K., Rape, M., Thoms, S., Jentsch, S. EMBO J. (2002) [Pubmed]
  6. Oxygen sensing in yeast: evidence for the involvement of the respiratory chain in regulating the transcription of a subset of hypoxic genes. Kwast, K.E., Burke, P.V., Staahl, B.T., Poyton, R.O. Proc. Natl. Acad. Sci. U.S.A. (1999) [Pubmed]
  7. Membrane lipid perturbation modifies the set point of the temperature of heat shock response in yeast. Carratù, L., Franceschelli, S., Pardini, C.L., Kobayashi, G.S., Horvath, I., Vigh, L., Maresca, B. Proc. Natl. Acad. Sci. U.S.A. (1996) [Pubmed]
  8. Regulation of unsaturated fatty acid biosynthesis in Saccharomyces: the endoplasmic reticulum membrane protein, Mga2p, a transcription activator of the OLE1 gene, regulates the stability of the OLE1 mRNA through exosome-mediated mechanisms. Kandasamy, P., Vemula, M., Oh, C.S., Chellappa, R., Martin, C.E. J. Biol. Chem. (2004) [Pubmed]
  9. Regulatory elements that control transcription activation and unsaturated fatty acid-mediated repression of the Saccharomyces cerevisiae OLE1 gene. Choi, J.Y., Stukey, J., Hwang, S.Y., Martin, C.E. J. Biol. Chem. (1996) [Pubmed]
  10. The membrane proteins, Spt23p and Mga2p, play distinct roles in the activation of Saccharomyces cerevisiae OLE1 gene expression. Fatty acid-mediated regulation of Mga2p activity is independent of its proteolytic processing into a soluble transcription activator. Chellappa, R., Kandasamy, P., Oh, C.S., Jiang, Y., Vemula, M., Martin, C.E. J. Biol. Chem. (2001) [Pubmed]
  11. Isolation and characterization of mutations affecting expression of the delta9- fatty acid desaturase gene, OLE1, in Saccharomyces cerevisiae. Fujimori, K., Anamnart, S., Nakagawa, Y., Sugioka, S., Ohta, D., Oshima, Y., Yamada, Y., Harashima, S. FEBS Lett. (1997) [Pubmed]
  12. MGA2 or SPT23 is required for transcription of the delta9 fatty acid desaturase gene, OLE1, and nuclear membrane integrity in Saccharomyces cerevisiae. Zhang, S., Skalsky, Y., Garfinkel, D.J. Genetics (1999) [Pubmed]
  13. Transcriptional co-regulation of Saccharomyces cerevisiae alcohol acetyltransferase gene, ATF1 and delta-9 fatty acid desaturase gene, OLE1 by unsaturated fatty acids. Fujiwara, D., Yoshimoto, H., Sone, H., Harashima, S., Tamai, Y. Yeast (1998) [Pubmed]
  14. Delta-9 fatty acid desaturase gene containing a carboxyl-terminal cytochrome b5 domain from the red alga Cyanidioschyzon merolae. Itoh, R., Toda, K., Takahashi, H., Takano, H., Kuroiwa, T. Curr. Genet. (1998) [Pubmed]
  15. Rsp5p is required for ER bound Mga2p120 polyubiquitination and release of the processed/tethered transactivator Mga2p90. Shcherbik, N., Zoladek, T., Nickels, J.T., Haines, D.S. Curr. Biol. (2003) [Pubmed]
  16. Fatty acid-responsive control of mRNA stability. Unsaturated fatty acid-induced degradation of the Saccharomyces OLE1 transcript. Gonzalez, C.I., Martin, C.E. J. Biol. Chem. (1996) [Pubmed]
  17. Yeast adaptation to 2,4-dichlorophenoxyacetic acid involves increased membrane fatty acid saturation degree and decreased OLE1 transcription. Viegas, C.A., Cabral, M.G., Teixeira, M.C., Neumann, G., Heipieper, H.J., Sá-Correia, I. Biochem. Biophys. Res. Commun. (2005) [Pubmed]
  18. Isolation of Delta12 and omega3-fatty acid desaturase genes from the yeast Kluyveromyces lactis and their heterologous expression to produce linoleic and alpha-linolenic acids in Saccharomyces cerevisiae. Kainou, K., Kamisaka, Y., Kimura, K., Uemura, H. Yeast (2006) [Pubmed]
  19. Fah1p, a Saccharomyces cerevisiae cytochrome b5 fusion protein, and its Arabidopsis thaliana homolog that lacks the cytochrome b5 domain both function in the alpha-hydroxylation of sphingolipid-associated very long chain fatty acids. Mitchell, A.G., Martin, C.E. J. Biol. Chem. (1997) [Pubmed]
  20. Molecular cloning and characterization of the Delta9 fatty acid desaturase gene and its promoter region from Saccharomyces kluyveri. Kajiwara, S. FEMS Yeast Res. (2002) [Pubmed]
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