The LQT2-related mutation K525N, when combined with F627Y, switched the hERG channel from a depolarization-activated to a hyperpolarization-activated channel with a half-activation voltage of -103.2 mV.
A potential cooperation mechanism in the extracellular vestibule of the voltage-sensing domain and the pore domain determines the gating polarity in hERG channels, providing structural insights into LQT2-related mutations.
Absolute Event Rate: -103.2% vs -18.7%
BACKGROUND: Cyclic Nucleotide-Binding Domain (CNBD)-family channels display distinct voltage-sensing properties despite sharing sequence and structural similarity. For example, the human Ether-a-go-go Related Gene (hERG) channel and the Hyperpolarization-activated Cyclic Nucleotide-gated (HCN) channel share high amino acid sequence similarity and identical domain structures. hERG conducts outward current and is activated by positive membrane potentials (depolarization), whereas HCN conducts inward current and is activated by negative membrane potentials (hyperpolarization). The structural basis for the "opposite" voltage-sensing properties of hERG and HCN remains unknown. RESULTS: We found the voltage-sensing domain (VSD) involves in modulating the gating polarity of hERG. We identified that a long-QT syndrome type 2-related mutation within the VSD, K525N, mediated an inwardly rectifying non-deactivating current, perturbing the channel closure, but sparing the open state and inactivated state. K525N rescued the current of a non-functional mutation in the pore helix region (F627Y) of hERG. K525N&F627Y switched hERG into a hyperpolarization-activated channel. The reactivated inward current induced by hyperpolarization mediated by K525N&F627Y can be inhibited by E-4031 and dofetilide quite well. Moreover, we report an extracellular interaction between the S1 helix and the S5-P region is crucial for modulating the gating polarity. The alanine substitution of several residues in this region (F431A, C566A, I607A, and Y611A) impaired the inward current of K525N&F627Y. CONCLUSIONS: Our data provide evidence that a potential cooperation mechanism in the extracellular vestibule of the VSD and the PD would determine the gating polarity in hERG.
Liu et al. (Mon,) conducted a other in Long-QT syndrome type 2 (LQT2). K525N mutation vs. Wild-type hERG was evaluated on Half-activation voltage (V1/2). The LQT2-related mutation K525N, when combined with F627Y, switched the hERG channel from a depolarization-activated to a hyperpolarization-activated channel with a half-activation voltage of -103.2 mV.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: