title: Structural basis of action for a human ether-a-go-go-related gene 1 potassium channel activator.
abstract: Activation of human ether-a-go-go-related gene 1 (hERG1) K(+) channels mediates cardiac action potential repolarization. Drugs that activate hERG1 channels represent a mechanism-based approach for the treatment of long QT syndrome, a disorder of cardiac repolarization associated with ventricular arrhythmia and sudden death. Here, we characterize the mechanisms of action and the molecular determinants for binding of RPR260243 [(3R,4R)-4-[3-(6-methoxy-quinolin-4-yl)-3-oxo-propyl]-1-[3-(2,3,5-trifluoro-phenyl)-prop-2-ynyl]-piperidine-3-carboxylic acid] (RPR), a recently discovered hERG1 channel activator. Channels were heterologously expressed in Xenopus laevis oocytes, and currents were measured by using the two-microelectrode voltage-clamp technique. RPR induced a concentration-dependent slowing in the rate of channel deactivation and enhanced current magnitude by shifting the voltage dependence of inactivation to more positive potentials. This mechanism was confirmed by demonstrating that RPR slowed the rate of deactivation, but did not increase current magnitude of inactivation-deficient mutant channels. The effects of RPR on hERG1 kinetics and magnitude could be simulated by reducing three rate constants in a Markov model of channel gating. Point mutations of specific residues located in the S4-S5 linker or cytoplasmic ends of the S5 and S6 domains greatly attenuated or ablated the effects of 3 microM RPR on deactivation (five residues), inactivation (one residue), or both gating mechanisms (four residues). These findings define a putative binding site for RPR and confirm the importance of an interaction between the S4-S5 linker and the S6 domain in electromechanical coupling of voltage-gated K(+) channels.
authors: Nora Eccles Harrison Cardiovascular Research and Training Institute and Department of Physiology, University of Utah, 95 South 2000 East, Salt Lake City, UT 84112, USA.
authors: Matthew
authors: M
authors: Perry
authors: Frank B
authors: FB
authors: Sachse
authors: Michael C
authors: MC
authors: Sanguinetti
mesh_terms: D000818:Animals; D001665:Binding Sites; D004594:Electrophysiology; D051638:Ether-A-Go-Go Potassium Channels / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects; D008954:Models, Biological; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010880:Piperidines / Q000494:pharmacology*; D017434:Protein Structure, Tertiary; D011804:Quinolines / Q000494:pharmacology*; D013997:Time Factors; D014982:Xenopus laevis
chemical_list: D051638:Ether-A-Go-Go Potassium Channels; C496884:KCNH1 protein, human; D010880:Piperidines; D011804:Quinolines; C499186:RPR260243
references: J Physiol. 1999 Feb 1;514 ( Pt 3):667-75
references: 9882738
references: Mol Pharmacol. 2005 Mar;67(3):827-36
references: 15548764
references: Trends Pharmacol Sci. 2005 Mar;26(3):119-24
references: 15749156
references: Mol Pharmacol. 2005 Apr;67(4):1009-17
references: 15662042
references: J Neurosci. 2005 May 18;25(20):5051-60
references: 15901787
references: Science. 2005 Aug 5;309(5736):897-903
references: 16002581
references: Mol Pharmacol. 2005 Sep;68(3):876-84
references: 15976038
references: J Intern Med. 2006 Jan;259(1):39-47
references: 16336512
references: Mol Pharmacol. 2006 Jan;69(1):266-77
references: 16219910
references: Mol Pharmacol. 2006 Feb;69(2):658-65
references: 16284303
references: J Biol Chem. 2006 May 5;281(18):12858-64
references: 16524878
references: Nat Chem Biol. 2007 May;3(5):287-96
references: 17435769
references: Pflugers Arch. 1993 Jan;422(4):354-63
references: 8437886
references: Circulation. 2000 Feb 15;101(6):616-23
references: 10673253
references: Proc Natl Acad Sci U S A. 2000 Oct 24;97(22):12329-33
references: 11005845
references: Cell. 2001 Feb 23;104(4):569-80
references: 11239413
references: J Physiol. 2001 Dec 15;537(Pt 3):843-51
references: 11744759
references: J Biol Chem. 2002 May 24;277(21):18994-9000
references: 11864984
references: J Gen Physiol. 2002 Nov;120(5):723-37
references: 12407082
references: Circ Res. 2003 Nov 14;93(10):941-7
references: 14576198
references: Circulation. 2004 Jan 6;109(1):30-5
references: 14676148
references: J Biol Chem. 2004 Mar 12;279(11):10120-7
references: 14699101
references: Circ Res. 2004 Apr 2;94(6):810-9
references: 14963001
references: Nature. 2004 Apr 22;428(6985):864-8
references: 15103379
references: Am J Physiol Heart Circ Physiol. 2004 Jun;286(6):H2342-51
references: 14962839
references: Biophys J. 2004 Sep;87(3):1507-25
references: 15345532
references: J Biol Chem. 2004 Oct 22;279(43):44690-4
references: 15304481
references: J Gen Physiol. 1990 Jul;96(1):195-215
references: 2170562
references: Methods Enzymol. 1992;207:319-39
references: 1382188
references: Cell. 1995 Mar 10;80(5):795-803
references: 7889573
references: Cell. 1995 Apr 21;81(2):299-307
references: 7736582
references: Science. 1995 Jul 7;269(5220):92-5
references: 7604285
references: Nature. 1996 Feb 29;379(6568):833-6
references: 8587608
references: Circ Res. 1998 Feb 23;82(3):386-95
references: 9486667
references: J Physiol. 1998 May 15;509 ( Pt 1):129-37
references: 9547387
references: Methods Enzymol. 1998;293:529-56
references: 9711627
references: J Gen Physiol. 1998 Oct;112(4):377-89
references: 9758858