Importance of general regulatory factors Rap1p, Abf1p and Reb1p for the activation of yeast fatty acid synthase genes FAS1 and FAS2.
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.
Schüller
H J
HJ
Institut für Mikrobiologie, Biochemie und Genetik, Universität Erlangen/Nürnberg, Germany.
Schütz
A
A
Knab
S
S
Hoffmann
B
B
Schweizer
E
E
D001483:Base Sequence; D001665:Binding Sites; D004271:DNA, Fungal / Q000737:chemistry / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D064429:Fatty Acid Synthases / Q000096:biosynthesis* / Q000235:genetics; D005656:Fungal Proteins / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D011401:Promoter Regions, Genetic; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D017384:Sequence Deletion; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D020668:rap GTP-Binding Proteins
C061886:ABF1 protein, S cerevisiae; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D009838:Oligodeoxyribonucleotides; C065681:REB1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D064429:Fatty Acid Synthases; D019204:GTP-Binding Proteins; D020668:rap GTP-Binding Proteins