A HETERODIMER OF THE ZN(2)CYS(6) TRANSCRIPTION FACTORS PIP2P AND OAF1P CONTROLS INDUCTION OF GENES ENCODING PEROXISOMAL PROTEINS IN SACCHAROMYCES-CEREVISIAE

In the yeast Saccharomyces cerevisiae, two transcriptional activators belonging to the Zn(2)Cys(6) protein family, Pip2p and Oaf1p, are invo lved in fatty-acid-dependent induction of genes encoding peroxisomal p roteins. This induction is mediated via an upstream activation sequenc e called the oleate-response element (ORE). DNA-bandshift experiments with ORE probes and epitope-tagged proteins showed that two binary com plexes occurred: in wild-type cells the major complex consisted of a P ip2p . Oaf1p heterodimer, but in cells in which Oaf1p was overexpresse d an Oaf1p homodimer was also observed. The genes encoding Oaf1p and P ip2p were controlled in different ways. The OAF1 gene was constitutive ly expressed, while the PIP2 gene was induced upon growth on oleate, g iving rise to positive autoregulatory control. We have shown that the Pip2p . Oaf1p heterodimer is responsible for the strong expression of the genes encoding peroxisomal proteins upon growth on oleate. Pip2p a nd Oaf1p form an example of a heterodimere of yeast Zn(2)Cys(6) zinc-f inger proteins binding to DNA.