| Structural highlights
Disease
[KCNH2_HUMAN] Defects in KCNH2 are the cause of long QT syndrome type 2 (LQT2) [MIM:613688]. Long QT syndromes are heart disorders characterized by a prolonged QT interval on the ECG and polymorphic ventricular arrhythmias. They cause syncope and sudden death in response to exercise or emotional stress. Deafness is often associated with LQT2.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] Defects in KCNH2 are the cause of short QT syndrome type 1 (SQT1) [MIM:609620]. Short QT syndromes are heart disorders characterized by idiopathic persistently and uniformly short QT interval on ECG in the absence of structural heart disease in affected individuals. They cause syncope and sudden death.[25] [26]
Function
[KCNH2_HUMAN] Pore-forming (alpha) subunit of voltage-gated inwardly rectifying potassium channel. Channel properties are modulated by cAMP and subunit assembly. Mediates the rapidly activating component of the delayed rectifying potassium current in heart (IKr). Isoform 3 has no channel activity by itself, but modulates channel characteristics when associated with isoform 1.
Publication Abstract from PubMed
Human ether-a-go-go related gene (hERG) K+ channels have a critical role in cardiac repolarisation. hERG channels close (deactivate) very slowly and this is vital for regulating the time-course and amplitude of repolarising current during the cardiac action potential. Accelerated deactivation is one mechanism by which inherited mutations cause long QT syndrome and potentially lethal arrhythmias. hERG deactivation is highly dependent upon an intact eag domain (the first 135 amino acids of the N-terminus). Importantly, deletion of residues 2-26 accelerates deactivation to a similar extent as removing the entire eag domain. These and other experiments suggest the first 26 residues (NT1-26) contain structural elements required to slow deactivation by stabilising the open conformation of the pore. Residues 26-135 form a PAS domain, but a structure for NT1-26 has not been forthcoming and little is known about its site of interaction on the channel. In this study, we present an NMR structure for the entire eag domain, which reveals that NT1-26 is structurally independent from the PAS domain and contains a stable amphipathic helix with one face being positively charged. Mutagenesis and electrophysiological studies indicate that neutralising basic residues and breaking the amphipathic helix dramatically accelerate deactivation. Furthermore, scanning mutagenesis and molecular modelling studies of the cyclic nucleotide binding domain (cNBD) suggest that negatively charged patches on its cytoplasmic surface form an interface with the NT1-26 domain. We propose a model in which NT1-26 obstructs gating motions of the cNBD to allosterically stabilise the open conformation of the pore.
Mechanistic insight into hERG K+ channel deactivation gating from the solution structure of the EAG domain.,Muskett FW, Thouta S, Thomson SJ, Bowen A, Stansfeld PJ, Mitcheson JS J Biol Chem. 2010 Dec 6. PMID:21135103[27]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Gong Q, Jones MA, Zhou Z. Mechanisms of pharmacological rescue of trafficking-defective hERG mutant channels in human long QT syndrome. J Biol Chem. 2006 Feb 17;281(7):4069-74. Epub 2005 Dec 16. PMID:16361248 doi:10.1074/jbc.M511765200
- ↑ Itoh T, Tanaka T, Nagai R, Kamiya T, Sawayama T, Nakayama T, Tomoike H, Sakurada H, Yazaki Y, Nakamura Y. Genomic organization and mutational analysis of HERG, a gene responsible for familial long QT syndrome. Hum Genet. 1998 Apr;102(4):435-9. PMID:9600240
- ↑ Curran ME, Splawski I, Timothy KW, Vincent GM, Green ED, Keating MT. A molecular basis for cardiac arrhythmia: HERG mutations cause long QT syndrome. Cell. 1995 Mar 10;80(5):795-803. PMID:7889573
- ↑ Satler CA, Walsh EP, Vesely MR, Plummer MH, Ginsburg GS, Jacob HJ. Novel missense mutation in the cyclic nucleotide-binding domain of HERG causes long QT syndrome. Am J Med Genet. 1996 Oct 2;65(1):27-35. PMID:8914737 doi:<27::AID-AJMG4>3.0.CO;2-V 10.1002/(SICI)1096-8628(19961002)65:1<27::AID-AJMG4>3.0.CO;2-V
- ↑ Benson DW, MacRae CA, Vesely MR, Walsh EP, Seidman JG, Seidman CE, Satler CA. Missense mutation in the pore region of HERG causes familial long QT syndrome. Circulation. 1996 May 15;93(10):1791-5. PMID:8635257
- ↑ Dausse E, Berthet M, Denjoy I, Andre-Fouet X, Cruaud C, Bennaceur M, Faure S, Coumel P, Schwartz K, Guicheney P. A mutation in HERG associated with notched T waves in long QT syndrome. J Mol Cell Cardiol. 1996 Aug;28(8):1609-15. PMID:8877771 doi:10.1006/jmcc.1996.0151
- ↑ Tanaka T, Nagai R, Tomoike H, Takata S, Yano K, Yabuta K, Haneda N, Nakano O, Shibata A, Sawayama T, Kasai H, Yazaki Y, Nakamura Y. Four novel KVLQT1 and four novel HERG mutations in familial long-QT syndrome. Circulation. 1997 Feb 4;95(3):565-7. PMID:9024139
- ↑ Splawski I, Shen J, Timothy KW, Vincent GM, Lehmann MH, Keating MT. Genomic structure of three long QT syndrome genes: KVLQT1, HERG, and KCNE1. Genomics. 1998 Jul 1;51(1):86-97. PMID:9693036 doi:S0888-7543(98)95361-7
- ↑ Satler CA, Vesely MR, Duggal P, Ginsburg GS, Beggs AH. Multiple different missense mutations in the pore region of HERG in patients with long QT syndrome. Hum Genet. 1998 Mar;102(3):265-72. PMID:9544837
- ↑ Akimoto K, Furutani M, Imamura S, Furutani Y, Kasanuki H, Takao A, Momma K, Matsuoka R. Novel missense mutation (G601S) of HERG in a Japanese long QT syndrome family. Hum Mutat. 1998;Suppl 1:S184-6. PMID:9452080
- ↑ Berthet M, Denjoy I, Donger C, Demay L, Hammoude H, Klug D, Schulze-Bahr E, Richard P, Funke H, Schwartz K, Coumel P, Hainque B, Guicheney P. C-terminal HERG mutations: the role of hypokalemia and a KCNQ1-associated mutation in cardiac event occurrence. Circulation. 1999 Mar 23;99(11):1464-70. PMID:10086971
- ↑ Jongbloed RJ, Wilde AA, Geelen JL, Doevendans P, Schaap C, Van Langen I, van Tintelen JP, Cobben JM, Beaufort-Krol GC, Geraedts JP, Smeets HJ. Novel KCNQ1 and HERG missense mutations in Dutch long-QT families. Hum Mutat. 1999;13(4):301-10. PMID:10220144 doi:<301::AID-HUMU7>3.0.CO;2-V 10.1002/(SICI)1098-1004(1999)13:4<301::AID-HUMU7>3.0.CO;2-V
- ↑ Chen J, Zou A, Splawski I, Keating MT, Sanguinetti MC. Long QT syndrome-associated mutations in the Per-Arnt-Sim (PAS) domain of HERG potassium channels accelerate channel deactivation. J Biol Chem. 1999 Apr 9;274(15):10113-8. PMID:10187793
- ↑ Yoshida H, Horie M, Otani H, Takano M, Tsuji K, Kubota T, Fukunami M, Sasayama S. Characterization of a novel missense mutation in the pore of HERG in a patient with long QT syndrome. J Cardiovasc Electrophysiol. 1999 Sep;10(9):1262-70. PMID:10517660
- ↑ Larsen LA, Svendsen IH, Jensen AM, Kanters JK, Andersen PS, Moller M, Sorensen SA, Sandoe E, Jacobsen JR, Vuust J, Christiansen M. Long QT syndrome with a high mortality rate caused by a novel G572R missense mutation in KCNH2. Clin Genet. 2000 Feb;57(2):125-30. PMID:10735633
- ↑ Splawski I, Shen J, Timothy KW, Lehmann MH, Priori S, Robinson JL, Moss AJ, Schwartz PJ, Towbin JA, Vincent GM, Keating MT. Spectrum of mutations in long-QT syndrome genes. KVLQT1, HERG, SCN5A, KCNE1, and KCNE2. Circulation. 2000 Sep 5;102(10):1178-85. PMID:10973849
- ↑ Laitinen P, Fodstad H, Piippo K, Swan H, Toivonen L, Viitasalo M, Kaprio J, Kontula K. Survey of the coding region of the HERG gene in long QT syndrome reveals six novel mutations and an amino acid polymorphism with possible phenotypic effects. Hum Mutat. 2000 Jun;15(6):580-1. PMID:10862094 doi:<580::AID-HUMU16>3.0.CO;2-0 10.1002/1098-1004(200006)15:6<580::AID-HUMU16>3.0.CO;2-0
- ↑ Kagan A, Yu Z, Fishman GI, McDonald TV. The dominant negative LQT2 mutation A561V reduces wild-type HERG expression. J Biol Chem. 2000 Apr 14;275(15):11241-8. PMID:10753933
- ↑ Hayashi K, Shimizu M, Ino H, Yamaguchi M, Mabuchi H, Hoshi N, Higashida H. Characterization of a novel missense mutation E637K in the pore-S6 loop of HERG in a patient with long QT syndrome. Cardiovasc Res. 2002 Apr;54(1):67-76. PMID:12062363
- ↑ Paulussen A, Raes A, Matthijs G, Snyders DJ, Cohen N, Aerssens J. A novel mutation (T65P) in the PAS domain of the human potassium channel HERG results in the long QT syndrome by trafficking deficiency. J Biol Chem. 2002 Dec 13;277(50):48610-6. Epub 2002 Sep 26. PMID:12354768 doi:10.1074/jbc.M206569200
- ↑ Johnson WH Jr, Yang P, Yang T, Lau YR, Mostella BA, Wolff DJ, Roden DM, Benson DW. Clinical, genetic, and biophysical characterization of a homozygous HERG mutation causing severe neonatal long QT syndrome. Pediatr Res. 2003 May;53(5):744-8. Epub 2003 Mar 5. PMID:12621127 doi:10.1203/01.PDR.0000059750.17002.B6
- ↑ Westenskow P, Splawski I, Timothy KW, Keating MT, Sanguinetti MC. Compound mutations: a common cause of severe long-QT syndrome. Circulation. 2004 Apr 20;109(15):1834-41. Epub 2004 Mar 29. PMID:15051636 doi:10.1161/01.CIR.0000125524.34234.13
- ↑ Tester DJ, Will ML, Haglund CM, Ackerman MJ. Compendium of cardiac channel mutations in 541 consecutive unrelated patients referred for long QT syndrome genetic testing. Heart Rhythm. 2005 May;2(5):507-17. PMID:15840476 doi:10.1016/j.hrthm.2005.01.020
- ↑ Aidery P, Kisselbach J, Gaspar H, Baldea I, Schweizer PA, Becker R, Katus HA, Thomas D. Identification and functional characterization of the novel human ether-a-go-go-related gene (hERG) R744P mutant associated with hereditary long QT syndrome 2. Biochem Biophys Res Commun. 2012 Feb 24;418(4):830-5. doi:, 10.1016/j.bbrc.2012.01.118. Epub 2012 Jan 30. PMID:22314138 doi:10.1016/j.bbrc.2012.01.118
- ↑ Brugada R, Hong K, Dumaine R, Cordeiro J, Gaita F, Borggrefe M, Menendez TM, Brugada J, Pollevick GD, Wolpert C, Burashnikov E, Matsuo K, Wu YS, Guerchicoff A, Bianchi F, Giustetto C, Schimpf R, Brugada P, Antzelevitch C. Sudden death associated with short-QT syndrome linked to mutations in HERG. Circulation. 2004 Jan 6;109(1):30-5. Epub 2003 Dec 15. PMID:14676148 doi:10.1161/01.CIR.0000109482.92774.3A
- ↑ Hong K, Bjerregaard P, Gussak I, Brugada R. Short QT syndrome and atrial fibrillation caused by mutation in KCNH2. J Cardiovasc Electrophysiol. 2005 Apr;16(4):394-6. PMID:15828882 doi:JCE40621
- ↑ Muskett FW, Thouta S, Thomson SJ, Bowen A, Stansfeld PJ, Mitcheson JS. Mechanistic insight into hERG K+ channel deactivation gating from the solution structure of the EAG domain. J Biol Chem. 2010 Dec 6. PMID:21135103 doi:10.1074/jbc.M110.199364
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