title: Long QT mutations at the interface between KCNQ1 helix C and KCNE1 disrupt I(KS) regulation by PKA and PIP₂.
abstract: KCNQ1 and KCNE1 co-assembly generates the I(KS) K(+) current, which is crucial to the cardiac action potential repolarization. Mutations in their corresponding genes cause long QT syndrome (LQT) and atrial fibrillation. The A-kinase anchor protein, yotiao (also known as AKAP9), brings the I(KS) channel complex together with signaling proteins to achieve regulation upon β1-adrenergic stimulation. Recently, we have shown that KCNQ1 helix C interacts with the KCNE1 distal C-terminus. We postulated that this interface is crucial for I(KS) channel modulation. Here, we examined the yet unknown molecular mechanisms of LQT mutations located at this intracellular intersubunit interface. All LQT mutations disrupted the internal KCNQ1-KCNE1 intersubunit interaction. LQT mutants in KCNQ1 helix C led to a decreased current density and a depolarizing shift of channel activation, mainly arising from impaired phosphatidylinositol-4,5-bisphosphate (PIP2) modulation. In the KCNE1 distal C-terminus, the LQT mutation P127T suppressed yotiao-dependent cAMP-mediated upregulation of the I(KS) current, which was caused by reduced KCNQ1 phosphorylation at S27. Thus, KCNQ1 helix C is important for channel modulation by PIP2, whereas the KCNE1 distal C-terminus appears essential for the regulation of IKS by yotiao-mediated PKA phosphorylation.
authors.affiliation: Department of Physiology & Pharmacology, Tel Aviv University, Tel Aviv, 69978, Israel.
authors.forename: Meidan
authors.initials: M
authors.lastname: Dvir
authors.affiliation: Department of Biochemistry & Molecular Biology, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Roi
authors.initials: R
authors.lastname: Strulovich
authors.affiliation: Department of Biochemistry & Molecular Biology, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Dana
authors.initials: D
authors.lastname: Sachyani
authors.affiliation: Department of Physiology & Pharmacology, Tel Aviv University, Tel Aviv, 69978, Israel.
authors.forename: Inbal
authors.initials: I
authors.lastname: Ben-Tal Cohen
authors.affiliation: Department of Physiology & Pharmacology, Tel Aviv University, Tel Aviv, 69978, Israel.
authors.forename: Yoni
authors.initials: Y
authors.lastname: Haitin
authors.affiliation: Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX 77030, USA.
authors.forename: Carmen
authors.initials: C
authors.lastname: Dessauer
authors.affiliation: Institut für Physiologie, Universität des Saarlandes, 66424 Homburg, Germany.
authors.forename: Olaf
authors.initials: O
authors.lastname: Pongs
authors.affiliation: Department of Pharmacology, Columbia University, New York, NY 10027, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Kass
authors.affiliation: Department of Biochemistry & Molecular Biology, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Joel A
authors.initials: JA
authors.lastname: Hirsch
authors.affiliation: Department of Physiology & Pharmacology, Tel Aviv University, Tel Aviv, 69978, Israel battali@post.tau.ac.il.
authors.forename: Bernard
authors.initials: B
authors.lastname: Attali
mesh_terms: D054758:A Kinase Anchor Proteins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051657:KCNQ1 Potassium Channel / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008133:Long QT Syndrome / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D020125:Mutation, Missense; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism*; D010766:Phosphorylation; D024642:Potassium Channels, Voltage-Gated / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary
chemical_list: D054758:A Kinase Anchor Proteins; C119719:AKAP9 protein, human; D003598:Cytoskeletal Proteins; C489622:KCNE1 protein, human; D051657:KCNQ1 Potassium Channel; C496909:KCNQ1 protein, human; D019269:Phosphatidylinositol 4,5-Diphosphate; D024642:Potassium Channels, Voltage-Gated; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases
keywords: Arrhythmia; IKS; KCNE; KCNQ; Long QT; Potassium channel