Mutations in the bZIP domain of yeast GCN4 that alter DNA-binding specificity.

AUTOR(ES)

Tzamarias, D

RESUMO

The bZIP class of eukaryotic transcriptional regulators utilize a distinct structural motif that consists of a leucine zipper that mediates dimerization and an adjacent basic region that directly contacts DNA. Although models of the protein-DNA complex have been proposed, the basis of DNA-binding specificity is essentially unknown. By genetically selecting for derivatives of yeast GCN4 that activate transcription from promoters containing mutant binding sites, we isolate an altered-specificity mutant in which the invariant asparagine in the basic region of bZIP proteins (Asn-235) has been changed to tryptophan. Wild-type GCN4 binds the optimal site (ATGACTCAT) with much higher affinity than the mutant site (TTGACTCAA), whereas the Trp-235 protein binds these sites with similar affinity. Moreover, the Trp-235, Ala-235, and Gln-235 derivatives differ from GCN4 in their strong discrimination against GTGACTCAC. These results suggest a direct interaction between Asn-235 and the +/- 4 position of the DNA target site and are discussed in terms of the scissors-grip and induced-fork models of bZIP proteins.

Documentos Relacionados

• Replacement of invariant bZip residues within the basic region of the yeast transcriptional activator GCN4 can change its DNA binding specificity.
• Highly conserved residues in the bZIP domain of yeast GCN4 are not essential for DNA binding.
• DNA-mediated assembly of weakly interacting DNA-binding protein subunits: in vitro recruitment of phage 434 repressor and yeast GCN4 DNA-binding domains
• Defining the sequence specificity of DNA-binding proteins by selecting binding sites from random-sequence oligonucleotides: analysis of yeast GCN4 protein.
• DNA-binding domain of GCN4 induces bending of both the ATF/CREB and AP-1 binding sites of DNA