Characterization of a transcriptional control element involved in proliferation of peroxisomes in yeast in response to oleate.

Oleate induces the transcription of genes involved in peroxisome biogenesis and stimulates the proliferation of these organelles in Saccharomyces cerevisiae. Previously, we have reported the identification of a region containing a positive regulatory element in the 5' flanking region of the FOX3 gene encoding the peroxisomal enzyme 3-oxoacyl-CoA thiolase. This region contains a 23-bp imperfect inverted-repeat sequence. Full induction, in response to oleate, is mediated by the intact dyad. However, one half-site of the inverted repeat is also able to mediate induction of transcription in response to oleate, albeit to a small extent. Furthermore, the weak binding of protein to each part of the inverted repeat proved to be correlated with the weak activation of transcription, in support of oleate. A DNase-I footprint covered the entire dyad and DNA band-shift experiments indicated that one or more trans-acting factors bind to the imperfect palindrome. The binding of protein to this element seems to be correlated with transcriptional activation, since mutations in both halves of the inverted dyad affected both transcriptional activation and protein binding in vitro. Similar oleate-responsive elements are commonly found in the 5' flanking regions of genes encoding proteins involved in peroxisome biogenesis and the factor(s) binding to oleate-responsive element(s) could therefore be involved in coordination of the expression of oleate-inducible genes and the proliferation of peroxisomes.