Structural and functional characterization of the short acidic transcriptional activation region of yeast GCN4 protein.

Derivatives of the yeast GCN4 transcription factor containing acidic regions of 35 to 40 amino acids fused directly to the DNA-binding domain are fully functional in vivo. High resolution deletion analysis and proteolytic mapping suggest that the activation region is a repeated structure composed of small units acting additively. Acidic character is a feature of the structural motif, possibly a dimer of alpha-helices from two GCN4 monomers, that may be important for interactions with the basic transcriptional machinery.