Coordinate genetic control of yeast fatty acid synthase genes FAS1 and FAS2 by an upstream activation site common to genes involved in membrane lipid biosynthesis.
A systematic search for upstream controlling elements necessary for efficient expression of the yeast fatty acid synthase genes FAS1 and FAS2 revealed identical activation sites, UASFAS, in front of both FAS genes. The individual element confers, in a heterologous yeast test system, an approximately 40-fold stimulation of basal gene expression. The UASFAS motifs identified have the consensus sequence TYTTCACATGY and function in either orientation. The same sequence motif is found in the upstream regions of all so far characterized yeast genes encoding enzymes of phospholipid biosynthesis. In gel retardation assays, a protein factor, Fbf1 (FAS binding factor), was identified which interacted with UASFAS. The UASFAS motif proved to be an inositol/choline responsive element (ICRE) conferring strict repression by exogenous inositol and choline on a heterologous reporter gene. Its core sequence perfectly matches the CANNTG motif typical of basic helix-loop-helix DNA-binding proteins. In contrast to the individual UASFAS element, the intact yeast FAS promoters are not significantly influenced by inositol and choline, and thus allow nearly constitutive fatty acid synthase production. Available evidence suggests that additional cis- and trans-acting elements, other than UASFAS and Fbf1, are involved in this constitutive FAS gene expression.
Schüller
H J
HJ
Institut für Mikrobiologie und Biochemie, Lehrstuhl Biochemie, Erlangen, FRG.
Hahn
A
A
Tröster
F
F
Schütz
A
A
Schweizer
E
E
D001483:Base Sequence; D002794:Choline / Q000494:pharmacology; D016384:Consensus Sequence; D004252:DNA Mutational Analysis; D004794:Enzyme Repression; D064429:Fatty Acid Synthases / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D007294:Inositol / Q000494:pharmacology; D008563:Membrane Lipids / Q000378:metabolism; D008969:Molecular Sequence Data; D010743:Phospholipids / Q000378:metabolism; D011993:Recombinant Fusion Proteins; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics*; D014157:Transcription Factors
D008563:Membrane Lipids; D010743:Phospholipids; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D007294:Inositol; D064429:Fatty Acid Synthases; D002794:Choline