A novel element in the promoter of the Saccharomyces cerevisiae gene SPS19enhances ORE-dependent up-regulation in oleic acid and is essential for de-repression

In Saccharomyces cerevisiae cells grown on oleic acid, genes encoding enzym es of beta-oxidation are induced by the interaction of a transcription fact or composed of Pip2p and Oaf1p with an oleate response element (ORE) in the ir promoters. The SPS19 gene, which encodes peroxisomal 2,4-dienoyl-CoA red uctase, 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 S PS19 promoter was conducted using SPS19-lacZ reporter genes. In a reporter construct containing a deletion adjacent to the ORE, transcriptional activa tion of SPS19 in oleic acid medium was impaired. Together with an additiona l segment that overlaps a portion of the canonical ORE, this region forms a continuous element (termed UAS essential for de-repression of SPS19 when g lucose levels are low. The potentially bi-partite UAS(SPS19) element was ab le to initiate bi-directional transcription from a promoterless CYC1-lacZ r eporter construct under de-repression conditions, whereas the canonical ORE was not. In oleic acid-containing medium, UAS(SPS19) stimulated transcript ion 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 t o a transcriptional enhancer in the promoter of the sporulation-specific ge ne SPS4, was shown specifically to bind several proteins, including Pip2p a nd Oaf1p. We propose that UAS(SPS19) and other sequences like it are requir ed to enhance the transcriptional effects mediated by more specific respons e elements.