DETERMINANTS OF BINDING-SITE SPECIFICITY AMONG YEAST C6 ZINC CLUSTER PROTEINS

Related DNA binding proteins often recognize similar DNA sites but can distinguish among them with the use of different protein-DNA contacts . Here, it is shown that members of the C6 zinc cluster family of yeas t transcriptional activators distinguish related DNA sites by a differ ent mechanism. The DNA binding site for each of these proteins contain s identical nucleotide triplets (CGG ... CCG) but differs in the spaci ngs between the triplets. It is shown that zinc clusters of these prot eins work interchangeably to recognize the conserved triplets and that the region 19 amino acids to the carboxyl-terminal side of the zinc c luster, comprising the linker and the beginning of a dimerization elem ent as inferred from the GAL4 crystal structure, directs the protein t o its preferred site.