Distinct regions of Cu(I)·ACE1 contact two spatially resolved DNA major groove sites

The interaction between the Cu(I) · ACE1 (CuACE1) transcription factor and its DNA binding site in the yeast metallothionein gene was studied by systematically altering the DNA sequence through base substitution, modification, and deletions as well as by altering the protein structure through chemical modification. We show here that CuACE1 is comprised of two distinct domains that contact DNA through minor groove interactions located between two major groove interaction sites. The minor groove interactions are shown to be critical for formation of a stable CuACE1 · DNA complex. The NH₂-terminal segment of ACE1 is shown to contact the 5'-most distal major groove site.