Efficient expression and Zn(II)-dependent structure of the DNA binding domain of the yeast GAL4 protein

Three protein fragments of different sizes which contain the DNA binding domain of transcription factor GAL4 from Saccharomyces cerevisiae have been expressed in functional forms in Escherichia coli. DNase I footprinting and gel retardation assays showed that the purified proteins bound to the same DNA sequence on the gal1-gal10 promoter as intact GAL4 does. Denaturation-refolding experiments demonstrated that Zn(II) is necessary for maintenance of the conformation of the DNA binding domain of GAL4, as judged on UV-CD and ¹H-NMR measurements, as well as for specific DNA binding.