title: Structure of Aart, a designed six-finger zinc finger peptide, bound to DNA.
abstract: Cys2-His2 zinc fingers are one of the most common types of DNA-binding domains. Modifications to zinc-finger binding specificity have recently enabled custom DNA-binding proteins to be designed to a wide array of target sequences. We present here a 1.96 A structure of Aart, a designed six-zinc finger protein, bound to a consensus DNA target site. This is the first structure of a designed protein with six fingers, and was intended to provide insights into the unusual affinity and specificity characteristics of this protein. Most protein-DNA contacts were found to be consistent with expectations, while others were unanticipated or insufficient to explain specificity. Several were unexpectedly mediated by glycerol, water molecules or amino acid-base stacking interactions. These results challenge some conventional concepts of recognition, particularly the finding that triplets containing 5'A, C, or T are typically not specified by direct interaction with the amino acid in position 6 of the recognition helix.
authors.affiliation: UC Davis Genome Center and Department of Pharmacology, University of California, Davis, CA 95616, USA. djsegal@ucdavis.edu
authors.forename: David J
authors.initials: DJ
authors.lastname: Segal
authors.forename: Justin W
authors.initials: JW
authors.lastname: Crotty
authors.forename: Mital S
authors.initials: MS
authors.lastname: Bhakta
authors.forename: Carlos F
authors.initials: CF
authors.lastname: Barbas
authors.forename: Nancy C
authors.initials: NC
authors.lastname: Horton
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D005990:Glycerol / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009690:Nucleic Acid Conformation; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D016335:Zinc Fingers
chemical_list: D010455:Peptides; D004247:DNA; D005990:Glycerol