Isoleucine gate blocks K+ conduction in C-type inactivation
- Universidade de Brasilia, Brazil
- University of Chicago, United States
- University of Brasília, Brazil
- Université de Lorraine, France
Abstract
Many voltage-gated potassium (Kv) channels display a time-dependent phenomenon called C-type inactivation, whereby prolonged activation by voltage leads to the inhibition of ionic conduction, a process that involves a conformational change at the selectivity filter toward a non-conductive state. Recently, a high-resolution structure of a strongly inactivated triple-mutant channel kv1.2-kv2.1-3m revealed a novel conformation of the selectivity filter that is dilated at its outer end, distinct from the well-characterized conductive state. While the experimental structure was interpreted as the elusive non-conductive state, our molecular dynamics simulations and electrophysiological measurements show that the dilated filter of kv1.2-kv2.1-3m is conductive and, as such, cannot completely account for the inactivation of the channel observed in the structural experiments. The simulation shows that an additional conformational change, implicating isoleucine residues at position 398 along the pore lining segment S6, is required to effectively block ion conduction. The I398 residues from the four subunits act as a state-dependent hydrophobic gate located immediately beneath the selectivity filter. By mutating I398 to Asparagine, ion permeation can be resumed in the kv1.2-kv2.1-3m channel, which was not a reversion C-type inactivation, since AgTxII fails to block the ionic permeation of kv1.2-kv2.1-3m_I398N. As a critical piece of the C-type inactivation machinery, this structural feature is the potential target of a broad class of QA blockers and negatively charged activators thus opening new research directions towards the development of drugs that specifically modulate gating-states of Kv channels.
Data availability
All data considered in the study, including molecular configurations and scripts for MD simulations, MD trajectories, docking configurations and electrophysiology data, can be downloaded from the ZENODO repository 10.5281/zenodo.10938041.
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Isoleucine gate blocks K+ conduction in C-type inactivationZenodo, 10.5281/zenodo.10938041.
Article and author information
Author details
Christophe J Chipot
Francisco Bezanilla
Funding
National Institute of Health Sciences (R35-GM152124)
- Benoit Roux
National Institute of Health Sciences (R01GM030376)
- Francisco Bezanilla
National Science Foundation (OMA-2121044)
- Francisco Bezanilla
Pew Charitable Trusts (Fellow)
- Bernardo I Pinto
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: Electrophysiology using Xenopus oocytes, in compliance with protocole at University of Chicago.
Copyright
© 2024, Treptow et al.
This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited.
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Isoleucine gate blocks K+ conduction in C-type inactivation
eLife 13:e97696.
https://doi.org/10.7554/eLife.97696
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