DNA-binding properties of the Drosophila melanogaster zeste gene product

The ability of the zeste moiety of beta-galactosidase-zeste fusion proteins synthesized in Escherichia coli to bind specific DNA sequences was examined. Such fusion proteins recognize a region of the white locus upstream of the start of transcription; this region has previously been shown to be required for genetic interaction between the zeste and white loci. Another strong binding site was localized to a region between 50 and 205 nucleotides before the start of the Ubx transcriptional unit; expression of the bithorax complex is also known to be influenced by the zeste locus. Weaker binding sites were also seen in the vicinity of the bxd and Sgs-4 genes, but it is currently unclear whether these binding sites play a role in transvection effects. The DNA-binding activity of the zeste protein is restricted to a domain of approximately 90 amino acids near the N terminus. This domain does not appear to contain homeobox or zinc finger motifs found in other DNA-binding proteins. The DNA-binding domain is not disrupted by any currently characterized zeste mutations.