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Importance of general regulatory factors Rap1p, Abf1p and Reb1p for the activation of yeast fatty acid synthase genes FAS1 and FAS2
- Schuller, H.J., Schutz, A., Knab, S., Hoffmann, B., Schweizer, E.
- European journal of biochemistry 1994 v.225 no.1 pp. 213-222
- Saccharomyces cerevisiae, fatty-acid synthase, structural genes, gene expression, reporter genes, phospholipids, biosynthesis, transcription (genetics), mutation, promoter regions, gene activation, transcription factors, binding sites
- The fatty acid synthase genes FAS1 and FAS2 of the yeast Saccharomyces cerevisiae are under transcriptional control of pathway-specific regulators of phospholipid biosynthesis. However, site-directed mutagenesis of the respective cis-acting elements upstream of FAS1 and FAS2 revealed that additional sequences activating both genes must exist. A deletion analysis of the FAS1 promoter lacking the previously characterized inositol/choline-responsive-element motif defined a region (nucleotides -760 to -850) responsible for most of the remaining activation potency. Gel-retardation experiments and in-vitro DNase footprint studies proved the binding of the general regulatory factors Rap1p, Abf1p and Reb1p to this FAS1 upstream region. Mutation of the respective binding sites led to a drop of gene activation to 8% of the wild-type level. Similarly, we also demonstrated the presence of a Reb1p-binding site upstream of FAS2 and its importance for gene activation. Thus, in addition to the previously characterized FAS-binding factor 1 interacting with the inositol/choline-responsive-element motif, a second motif common to the promoter regions of both FAS genes could be identified. Transcription of yeast fatty acid synthase genes is therefore subjected to both the pathway-specific control affecting genes of phospholipid biosynthesis and to the activation by general transcription factors allowing a sufficiently high level of constitutive gene expression.