The yeast gene COQ5 is differentially regulated by Mig1p, Rtg3p and Hap2p.

Ubiquinone (CoQ) is an important component of the electron transport chain and serves to regenerate cellular anti-oxidants. In Saccharomyces cerevisiae, expression of the COQ5 gene, encoding for a C-methyltransferase involved in CoQ synthesis, is transcriptionally regulated by carbon source. We have identified three transcription factors involved in this regulation. Mig1p repressed COQ5 expression on dextrose, while Rtg1p/Rtg3p heterodimers up-regulated COQ5 expression on oleic acid. Hap2p modulated the response to oleic acid but did not have an effect in other nonfermentable carbon sources such as glycerol. These results suggest that the regulation of COQ5 gene expression by carbon source is multifactorial and involves the interaction of various transcription factors.