title: Three-dimensional structure of the S4-S5 segment of the Shaker potassium channel.
abstract: The propagation of action potentials during neuronal signal transduction in phospholipid membranes is mediated by ion channels, a diverse group of membrane proteins. The S4-S5 linker peptide (S4-S5), that connects the S4 and S5 transmembrane segments of voltage-gated potassium channels is an important region of the Shaker ion-channel protein. Despite its importance, very little is known about its structure. Here we provide evidence for an amphipathic alpha-helical conformation of a synthetic S4-S5 peptide of the voltage-gated Drosophila melanogaster Shaker potassium channel in water/trifluoroethanol and in aqueous phospholipid micelles. The three-dimensional solution structures of the S4-S5 peptide were obtained by high-resolution nuclear magnetic resonance spectroscopy and distance-geometry/simulated-annealing calculations. The detailed structural features are discussed with respect to model studies and available mutagenesis data on the mechanism and selectivity of the potassium channel.
authors.affiliation: Institut für Molekulare Biotechnologie, Centre for Design and Structure in Biology, D-07708 Jena, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Ohlenschläger
authors.forename: Hironobu
authors.initials: H
authors.lastname: Hojo
authors.forename: Ramadurai
authors.initials: R
authors.lastname: Ramachandran
authors.forename: Matthias
authors.initials: M
authors.lastname: Görlach
authors.forename: Parvez I
authors.initials: PI
authors.lastname: Haris
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015221:Potassium Channels / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D051637:Shaker Superfamily of Potassium Channels
chemical_list: D029721:Drosophila Proteins; D010446:Peptide Fragments; D015221:Potassium Channels; C496929:Sh protein, Drosophila; D051637:Shaker Superfamily of Potassium Channels