title: Elongation of outer transmembrane domain alters function of miniature K+ channel Kcv.
abstract: The virus-coded channel Kcv has the typical structure of a two-transmembrane domain K(+) channel. Exceptional are its cytoplasmic domains: the C terminus basically ends inside the membrane and, hence, precludes the formation of a cytoplasmic gate by the so-called bundle crossing; the cytoplasmic N terminus is composed of only 12 amino acids. According to structural predictions, it is positioned in the membrane/aqueous interface and connected via a proline kink to the outer transmembrane domain (TM1). Here, we show that this proline kink affects channel function by determining the position of TM1 in the membrane bilayer. Extension of the hydrophobic length of TM1 by either eliminating the proline kink or introducing an alanine in TM1 augments a time- and voltage-dependent inward rectification of the channel. This suggests that the positional information of TM1 in the bilayer is transmitted to a channel gate, which is not identical with the cytoplasmic bundle crossing.
authors.affiliation: Institute of Botany, University of Technology Darmstadt, Darmstadt, Germany.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Hertel
authors.forename: Sascha
authors.initials: S
authors.lastname: Tayefeh
authors.forename: Mario
authors.initials: M
authors.lastname: Mehmel
authors.forename: Stefan M
authors.initials: SM
authors.lastname: Kast
authors.forename: James
authors.initials: J
authors.lastname: Van Etten
authors.forename: Anna
authors.initials: A
authors.lastname: Moroni
authors.forename: Gerhard
authors.initials: G
authors.lastname: Thiel
mesh_terms: D019943:Amino Acid Substitution; D002460:Cell Line; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008564:Membrane Potentials / Q000235:genetics; D017354:Point Mutation; D015221:Potassium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary / Q000235:genetics; D013329:Structure-Activity Relationship; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: C405463:Kcv potassium channel, Chlorella virus; D015221:Potassium Channels; D014764:Viral Proteins