title: Kv7.1 ion channels require a lipid to couple voltage sensing to pore opening.
abstract: Voltage-gated ion channels generate dynamic ionic currents that are vital to the physiological functions of many tissues. These proteins contain separate voltage-sensing domains, which detect changes in transmembrane voltage, and pore domains, which conduct ions. Coupling of voltage sensing and pore opening is critical to the channel function and has been modeled as a protein-protein interaction between the two domains. Here, we show that coupling in Kv7.1 channels requires the lipid phosphatidylinositol 4,5-bisphosphate (PIP2). We found that voltage-sensing domain activation failed to open the pore in the absence of PIP2. This result is due to loss of coupling because PIP2 was also required for pore opening to affect voltage-sensing domain activation. We identified a critical site for PIP2-dependent coupling at the interface between the voltage-sensing domain and the pore domain. This site is actually a conserved lipid-binding site among different K(+) channels, suggesting that lipids play an important role in coupling in many ion channels.
authors.affiliation: Department of Biomedical Engineering, Cardiac Bioelectricity and Arrhythmia Center, Washington University in St. Louis, St. Louis, MO 63130-4862, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Zaydman
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Silva
authors.forename: Kelli
authors.initials: K
authors.lastname: Delaloye
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.forename: Hongwu
authors.initials: H
authors.lastname: Liang
authors.forename: H Peter
authors.initials: HP
authors.lastname: Larsson
authors.forename: Jingyi
authors.initials: J
authors.lastname: Shi
authors.forename: Jianmin
authors.initials: J
authors.lastname: Cui
mesh_terms: D000465:Algorithms; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D005260:Female; D006801:Humans; D015640:Ion Channel Gating / Q000235:genetics / Q000502:physiology*; D051657:KCNQ1 Potassium Channel / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008564:Membrane Potentials / Q000235:genetics / Q000502:physiology; D008954:Models, Biological; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009865:Oocytes / Q000378:metabolism / Q000502:physiology; D018408:Patch-Clamp Techniques; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D014982:Xenopus laevis
chemical_list: D051657:KCNQ1 Potassium Channel; D019269:Phosphatidylinositol 4,5-Diphosphate
keywords: KCNQ; channelopathy; electromechanical coupling; phosphoinositide; voltage channel