The zinc finger DNA-binding motif occurs in many proteins that regulate
eukaryotic gene expression. The crystal structure of a complex containing the
three zinc fingers from Zif268 (a mouse immediate early protein) and a consensus
DNA-binding site has been determined at 2.1 angstroms resolution and refined to
a crystallographic R factor of 18.2 percent. In this complex, the zinc fingers
bind in the major groove of B-DNA and wrap part way around the double helix.
Each finger has a similar relation to the DNA and makes its primary contacts in
a three-base pair subsite. Residues from the amino-terminal portion of an alpha
helix contact the bases, and most of the contracts are made with the
guanine-rich strand of the DNA. This structure provides a framework for
understanding how zinc fingers recognize DNA and suggests that this motif may
provide a useful basis for the design of novel DNA-binding proteins.
