title: High-resolution structures of variant Zif268-DNA complexes: implications for understanding zinc finger-DNA recognition.
abstract: BACKGROUND
  Zinc fingers of the Cys2-His2 class comprise one of the largest families of eukaryotic DNA-binding motifs and recognize a diverse set of DNA sequences. These proteins have a relatively simple modular structure and key base contacts are typically made by a few residues from each finger. These features make the zinc finger motif an attractive system for designing novel DNA-binding proteins and for exploring fundamental principles of protein-DNA recognition.
  
  
  RESULTS
  Here we report the X-ray crystal structures of zinc finger-DNA complexes involving three variants of Zif268, with multiple changes in the recognition helix of finger one. We describe the structure of each of these three-finger peptides bound to its corresponding target site. To help elucidate the differential basis for site-specific recognition, the structures of four other complexes containing various combinations of these peptides with alternative binding sites have also been determined.
  
  
  CONCLUSIONS
  The protein-DNA contacts observed in these complexes reveal the basis for the specificity demonstrated by these Zif268 variants. Many, but not all, of the contacts can be rationalized in terms of a recognition code, but the predictive value of such a code is limited. The structures illustrate how modest changes in the docking arrangement accommodate the new sidechain-base and sidechain-phosphate interactions. Such adaptations help explain the versatility of naturally occurring zinc finger proteins and their utility in design.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: M
authors.initials: M
authors.lastname: Elrod-Erickson
authors.forename: T E
authors.initials: TE
authors.lastname: Benson
authors.forename: C O
authors.initials: CO
authors.lastname: Pabo
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites / Q000502:physiology; D018360:Crystallography, X-Ray; D004268:DNA-Binding Proteins / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry*; D010446:Peptide Fragments / Q000737:chemistry; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D014157:Transcription Factors / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D016335:Zinc Fingers / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; D010446:Peptide Fragments; D014157:Transcription Factors; D014867:Water