Chromatin structure and regulation of the eukaryotic regulatory gene GAL80

The chromatin structure around the 5' end of the yeast regulatory gene GAL80 has been determined. The chromatin organization is very similar to that on the 5' regions of the GAL1-10 structural genes: a constitutive hypersensitive region containing the upstream activating sequence (UAS) element, and nucleosomes around this hypersensitive region. The downstream nucleosome, which is a positioned nucleosome, covers the TATA and transcription start sites. The nucleosome upstream of the hypersensitive region undergoes significant change when cells are grown in galactose, where GAL80 gene expression is induced to maximal levels. The change may be related to the induction process. GAL4 protein binds strongly to the GAL80 UAS in galactose-grown cells, less strongly in glycerol-grown cells, and not at all in glucose-grown cells. These data and published gene expression data are used to develop a model for the regulation of the GAL80 regulatory gene.