Solution structure of a zinc finger domain of yeast ADR1

Abstract

The “zinc finger” is a 30-residue repeating motif that has been identified in a variety of eukaryotic transcription factors. Each domain is capable of binding a Zn²⁺ ion through invariant Cys and His residues. We have determined the three-dimensional structure of a synthetic peptide that corresponds to one of the two zinc finger domains in the yeast transcription factor ADR1, using two-dimensional nuclear magnetic resonance spectroscopy. The Zn²⁺ -bound structure of the peptide consists of a loop containing the two Cys residues, a “fingertip,” a 12- to 13-residue α-helix containing the two His residues, and a C-terminal tail. A majority of the interrresidue contacts observed invlove the seven conserved residues of the prototypic zinc finger (i.e., four zinc ligands and the three hydrophobic residues), indicating that these residues are largely responsible for the three-dimensional structure of the domain and that all the zinc finger domains of the TFIIIA class will have similar structures, with the highest concentration of such residues on the external face of the α-helix.