A novel element in the promoter of the Saccharomyces cerevisiae gene SPS19 enhances ORE-dependent up-regulation in oleic acid and is essential for de-repression.

In Saccharomyces cerevisiae cells grown on oleic acid, genes encoding enzymes of beta-oxidation are induced by the interaction of a transcription factor composed of Pip2p and Oaflp with an oleate response element (ORE) in their promoters. The SPS19 gene, which encodes peroxisomal 2,4-dienoyl-CoA reductase, an auxiliary beta-oxidation enzyme, has been shown previously to be up-regulated by a canonical ORE. To determine whether additional elements contribute to this transcriptional upregulation, deletion analysis of the SPS19 promoter was conducted using SPS19-lacZ reporter genes. In a reporter construct containing a deletion adjacent to the ORE, transcriptional activation of SPS19 in oleic acid medium was impaired. Together with an additional segment that overlaps a portion of the canonical ORE, this region forms a continuous element (termed UAS(SPS19)) that is essential for de-repression of SPS19 when glucose levels are low. The potentially bi-partite UAS(SPS19) element was able to initiate bi-directional transcription from a promoterless CYC1-lacZ reporter construct under de-repression conditions, whereas the canonical ORE was not. In oleic acid-containing medium, UAS(SPS19) stimulated transcription of the reporter gene 2.4-fold compared to the intact SPS19 ORE, but did so only in the presence of Pip2p and Oaf1p. UAS(SPS19), which is similar to a transcriptional enhancer in the promoter of the sporulation-specific gene SPS4, was shown specifically to bind several proteins, including Pip2p and Oaflp. We propose that UAS(SPS19) and other sequences like it are required to enhance the transcriptional effects mediated by more specific response elements.