title: Intracellular domains interactions and gated motions of I(KS) potassium channel subunits.
abstract: Voltage-gated K(+) channels co-assemble with auxiliary beta subunits to form macromolecular complexes. In heart, assembly of Kv7.1 pore-forming subunits with KCNE1 beta subunits generates the repolarizing K(+) current I(KS). However, the detailed nature of their interface remains unknown. Mutations in either Kv7.1 or KCNE1 produce the life-threatening long or short QT syndromes. Here, we studied the interactions and voltage-dependent motions of I(KS) channel intracellular domains, using fluorescence resonance energy transfer combined with voltage-clamp recording and in vitro binding of purified proteins. The results indicate that the KCNE1 distal C-terminus interacts with the coiled-coil helix C of the Kv7.1 tetramerization domain. This association is important for I(KS) channel assembly rules as underscored by Kv7.1 current inhibition produced by a dominant-negative C-terminal domain. On channel opening, the C-termini of Kv7.1 and KCNE1 come close together. Co-expression of Kv7.1 with the KCNE1 long QT mutant D76N abolished the K(+) currents and gated motions. Thus, during channel gating KCNE1 is not static. Instead, the C-termini of both subunits experience molecular motions, which are disrupted by the D76N causing disease mutation.
authors.affiliation: Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Yoni
authors.initials: Y
authors.lastname: Haitin
authors.forename: Reuven
authors.initials: R
authors.lastname: Wiener
authors.forename: Dana
authors.initials: D
authors.lastname: Shaham
authors.forename: Asher
authors.initials: A
authors.lastname: Peretz
authors.forename: Enbal Ben-Tal
authors.initials: EB
authors.lastname: Cohen
authors.forename: Liora
authors.initials: L
authors.lastname: Shamgar
authors.forename: Olaf
authors.initials: O
authors.lastname: Pongs
authors.forename: Joel A
authors.initials: JA
authors.lastname: Hirsch
authors.forename: Bernard
authors.initials: B
authors.lastname: Attali
mesh_terms: D000818:Animals; D002460:Cell Line; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D047468:Immunoprecipitation; D051657:KCNQ1 Potassium Channel / Q000737:chemistry / Q000378:metabolism*; D009865:Oocytes; D024642:Potassium Channels, Voltage-Gated / Q000737:chemistry / Q000378:metabolism*; D054730:Protein Interaction Domains and Motifs; D014981:Xenopus
chemical_list: C489622:KCNE1 protein, human; D051657:KCNQ1 Potassium Channel; D024642:Potassium Channels, Voltage-Gated; C059983:potassium channel protein I(sk)