Lipid regulation of hERG1 channel function

Williams E Miranda,Jiqing Guo,Valentina Corradi,D Peter Tieleman,Henry J Duff,Haydee Mesa-Galloso,Sergei Yu Noskov,James P Lees-Miller

doi:10.1038/s41467-021-21681-8

Williams E Miranda, Jiqing Guo + Show 6 more

Open Access

https://doi.org/10.1038/s41467-021-21681-8

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Abstract

The lipid regulation of mammalian ion channel function has emerged as a fundamental mechanism in the control of electrical signalling and transport specificity in various cell types. In this work, we combine molecular dynamics simulations, mutagenesis, and electrophysiology to provide mechanistic insights into how lipophilic molecules (ceramide-sphingolipid probe) alter gating kinetics and K+ currents of hERG1. We show that the sphingolipid probe induced a significant left shift of activation voltage, faster deactivation rates, and current blockade comparable to traditional hERG1 blockers. Microseconds-long MD simulations followed by experimental mutagenesis elucidated ceramide specific binding locations at the interface between the pore and voltage sensing domains. This region constitutes a unique crevice present in mammalian channels with a non-swapped topology. The combined experimental and simulation data provide evidence for ceramide-induced allosteric modulation of the channel by a conformational selection mechanism.

Highlights

The lipid regulation of mammalian ion channel function has emerged as a fundamental mechanism in the control of electrical signalling and transport specificity in various cell types
The CER2 did not decrease WT currents to 50% even at the highest concentration of 500 μM studied (Supplementary Fig. 1a). These results indicate that CER6 is the strongest channel hERG1 variant WTa B Y652Aa F656Ca M651Ta F557La
Our experiments and simulations show that ceramide–channel interactions can be simultaneously modulated by Pore Domain (PD) states and accessibility to residues at the Voltage-Sensing Domain (VSD)–PD interface of the channel

Summary

Introduction

The lipid regulation of mammalian ion channel function has emerged as a fundamental mechanism in the control of electrical signalling and transport specificity in various cell types. Microseconds-long MD simulations followed by experimental mutagenesis elucidated ceramide specific binding locations at the interface between the pore and voltage sensing domains This region constitutes a unique crevice present in mammalian channels with a non-swapped topology. ERG, HCN and CNG families feature a distinctive packing of the Voltage-Sensing Domain (VSD) against the Pore Domain (PD), known as nonswapped topology This unique topology may be linked to dramatically different permeation and gating regulatory mechanisms compared to well-studied canonical swapped domain channels[11]. We combined molecular dynamics (MD) simulations at the coarse-grained (CG) and all-atom (AA) levels of resolution using the workflow recently developed[4] with mutagenesis and electrophysiology experiments to understand the molecular mechanisms by which membrane-localized ceramides modulate hERG1 function. Our electrophysiology experiments show that ceramide application results in activation of the channel at more hyperpolarized potentials, faster deactivation rates, and block of K+

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