Long QT syndrome-associated mutations in the Per-Arnt-Sim (PAS) domain of HERG potassium channels accelerate channel deactivation.
Mutations in the human ether-a-go-go-related gene (HERG) cause long QT syndrome, an inherited disorder of cardiac repolarization that predisposes affected individuals to life-threatening arrhythmias. HERG encodes the cardiac rapid delayed rectifier potassium channel that mediates repolarization of ventricular action potentials. In this study, we used the oocyte expression system and voltage clamp techniques to determine the functional consequences of eight long QT syndrome-associated mutations located in the amino-terminal region of HERG (F29L, N33T, G53R, R56Q, C66G, H70R, A78P, and L86R). Mutant subunits formed functional channels with altered gating properties when expressed alone in oocytes. Deactivation was accelerated by all mutations. Some mutants shifted the voltage dependence of channel availability to more positive potentials. Voltage ramps indicated that fast deactivation of mutant channels would reduce outward current during the repolarization phase of the cardiac action potential and cause prolongation of the corrected QT interval, QTc. The amino-terminal region of HERG was recently crystallized and shown to possess a Per-Arnt-Sim (PAS) domain. The location of these mutations suggests they may disrupt the PAS domain and interfere with its interaction with the S4-S5 linker of the HERG channel.
Chen
J
J
Department of Medicine, Division of Cardiology, University of Utah, Salt Lake City, Utah 84112, USA.
Zou
A
A
Splawski
I
I
Keating
M T
MT
Sanguinetti
M C
MC
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D027682:Cation Transport Proteins; D004268:DNA-Binding Proteins; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; D018257:Helix-Loop-Helix Motifs; D006801:Humans; D008133:Long QT Syndrome / Q000235:genetics*; D009154:Mutation; D009865:Oocytes / Q000378:metabolism; D015221:Potassium Channels / Q000235:genetics*; D024642:Potassium Channels, Voltage-Gated; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D015534:Trans-Activators / Q000737:chemistry; D000071230:Transcriptional Regulator ERG; D014162:Transfection; D014982:Xenopus laevis; D000099162:Endothelial PAS Domain-Containing Protein 1
D051792:Basic Helix-Loop-Helix Proteins; D027682:Cation Transport Proteins; D004268:DNA-Binding Proteins; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D015534:Trans-Activators; D000071230:Transcriptional Regulator ERG; D000099162:Endothelial PAS Domain-Containing Protein 1; C072312:ERG protein, human; C000606913:KCNH2 protein, human; C092509:KCNH6 protein, human