title: Crystal structures of a single coiled-coil peptide in two oligomeric states reveal the basis for structural polymorphism.
abstract: Each protein sequence generally adopts a single native fold, but the sequence features that confer structural uniqueness are not well understood. To define the basis for structural heterogeneity, we determined the high resolution X-ray crystal structures of a single GCN4 leucine-zipper mutant (Asn 16 to aminobutyric acid) in both dimeric and trimeric coiled-coil conformations. The mutant sequence is accommodated in two distinct structures by forming similarly-shaped packing surfaces with different sets of atoms. The trimer structure, in comparison to a previously-characterized trimeric mutant with substitutions in eight core residues, shows that the twist of individual helices and the helix-helix crossing angles can vary significantly to produce the most favoured packing arrangement.
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley 94720-3206, USA.
authors.forename: L
authors.initials: L
authors.lastname: Gonzalez
authors.forename: R A
authors.initials: RA
authors.lastname: Brown
authors.forename: D
authors.initials: D
authors.lastname: Richardson
authors.forename: T
authors.initials: T
authors.lastname: Alber
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D004268:DNA-Binding Proteins; D019281:Dimerization; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics; D016350:Leucine Zippers; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D011487:Protein Conformation; D011494:Protein Kinases / Q000737:chemistry* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases