AFFINITY OF CUP2, A COPPER-DEPENDENT TRANSCRIPTION FACTOR, FOR DNA SEQUENCES UPSTREAM OF THE YEAST METALLOTHIONEIN GENE

摘要

CUP2, the protein that regulates the expression of the copper metallothionein gene of the yeast Saccharomyces cerevisiae, itself contains a copper cluster that is essential for activity. One of the binding sites for CUP2 upstream of the metallothionein gene, called the UASc, contains an imperfect inverted DNA sequence repeat. We have measured the binding affinity of CUPZ to the two half-sites of the UASc in five different DNA molecules, each containing one or two half-sites. The values of the dissociation constants we found were as follows: one upstream half-site, 1.25 nM; two upstream half-sites, 1.57 nM; one downstream half-site, 10.19 nM; two downstream half-sites, 10.37 nM; the wild type UASc site, 1.68 nM and 10.37 nM. We found no evidence for cooperativity in the interaction of CUP2 with any of the DNA molecules containing two half-sites. [References: 17]