Regulatory Elements That Control Transcription Activation and Unsaturated Fatty Acid-mediated Repression of the Saccharomyces cerevisiae OLE1 Gene

Abstract

In Saccharomyces cerevisiae, unsaturated fatty acids are formed from saturated acyl-CoA precursors by Ole1p, a ⌬-9 fatty acid desaturase. OLE1 mRNA levels are differentially regulated by the addition of saturated or unsaturated fatty acids to the growth medium. One component of this regulation system involves the control of OLE1 transcription. Saturated fatty acids induce a 1.6-fold increase in transcription activity, whereas a large family of unsaturated fatty acids repress OLE1 transcription as much as 60-fold. 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. Deletion of an 88-bp sequence within that region resulted in a complete loss in transcription activation and unsaturated fatty acid regulation. The 111-bp FAR element strongly activates transcription and confers unsaturated fatty acid regulation on a heterologous CYC1 promoter test plasmid. Essential elements required for unsaturated fatty acid repression of OLE1 were found in the 5 and 3 region of the 111-bp sequence. The FAR element-mediated activation and fatty acid repression of transcription was found to be closely tied to fatty acyl-CoA metabolism. Two fatty acid activation genes, FAA1 and FAA4, were found to be essential for unsaturated fatty acid repression of OLE1 through the FAR sequences. Disruption of either gene results in reduced levels of unsaturated fatty acid repression; disruption of both genes completely blocks the regulatory response. Acyl-CoA binding protein (ACBP) plays a role in determining the level of FAR element activated transcription. Disruption of the ACBP gene causes a >5-fold activation of OLE1 transcription and a similar increase in OLE1 mRNA levels. Unsaturated fatty acid repression of OLE1 transcription, however, is not affected by the disrupted ACBP gene. These studies show that promoter elements responsible for unsaturated fatty acid-mediated transcription repression are tightly linked to OLE1 activation sequences and that OLE1 transcription levels are closely tied to acyl-CoA metabolism.

A secreted lipase encoded by LIP1 is necessary for efficient use of saturated triglyceride lipids in Fusarium graminearum

“…In S. cerevisiae, a similar pattern of regulation of the OLE1 gene, which encodes the D-9 desaturase, has been reported; the level of OLE1 gene transcription was increased in response to exogenous saturated fatty acids, whereas exposure to unsaturated fatty acids sharply reduced transcription (McDonough et al, 1992). Although the corresponding positive and negative response elements have been characterized in the OLE1 upstream promoter region (Choi et al, 1996;McDonough et al, 1992), preliminary sequence comparison did not reveal the same elements present in the upstream region of the LIP1 gene. The transcription activation and/or repression elements required for fattyacid-mediated LIP1 expression remain to be determined.…”

A dual signalling pathway for the hypoxic expression of lipid genes, dependent on the glucose sensor Rag4, is revealed by the analysis of the KlMGA2 gene in Kluyveromyces lactis

“…Quantitative analysis of signals from repeated experiments (data not shown) demonstrated that the level of hypoxic expression of KlOLE1, similar to KlPDC1, was reduced but not abolished in the mutant strain. OLE1 is repressed by UFAs in S. cerevisiae (Choi et al, 1996). We tested the effect of UFAs on the hypoxic induction of KlOLE1.…”

Dosage-dependent functions of fatty acid desaturase Ole1p in growth and morphogenesis of Candida albicans

“…Also, the acyl-CoA binding protein and the Ssn6-Tup1 complex were shown to be involved in repression of OLE1 (Fujimori et al, 1997). On the other hand, the Hap1 transcriptional activator (Choi et al, 1996) and two transcription factors, Spt23 and Mga2p, which are initially synthesized as inactive ER-bound precursors, positively regulate OLE1 expression (Zhang et al, 1999). Ole1p is a naturally short-lived enzyme and is degraded by ubiquitin/ proteasome-dependent ER-associated degradation (Braun et al, 2002).…”

“…At low temperatures and during oxygen limitation, OLE1 expression is induced (Kwast et al, 1998;Nakagawa et al, 2002). A deletion analysis of the OLE1 promoter identified a 111 bp fatty acid-regulated region (FAR) which is essential for transcription activation and repression by unsaturated fatty acids (Choi et al, 1996). In addition, the low oxygen response promoter element (LORE) mediates oxygen repression of OLE1 (Nakagawa et al, 2001;Vasconcelles et al, 2001).…”