Trans-toxin ion-sensitivity of charybdotoxin-blocked potassium-channels reveals unbinding transitional states
- Universidad de Valparaíso, Chile
- Universidad de Talca, Chile
Abstract
In-silico and in-vitro studies have made progress in understanding protein-protein complexes formation; however, the molecular mechanisms for their dissociation are unclear. Protein-protein complexes, lasting from microseconds to years, often involve induced-fit, challenging computational or kinetic analysis. Charybdotoxin (CTX), a peptide from the Leiurus scorpion venom, blocks voltage-gated K+-channels in a unique example of binding/unbinding simplicity. CTX plugs the external mouth of K+-channels pore, stopping K+-ion conduction, without inducing conformational changes. Conflicting with a tight binding, we show that external permeant ions enhance CTX-dissociation, implying a path connecting the pore, in the toxin-bound channel, with the external solution. This sensitivity is explained if CTX wobbles between several bound conformations, producing transient events that restore the electrical and ionic trans-pore gradients. Wobbling may originate from a network of contacts in the interaction interface that are in dynamic stochastic equilibria. These partially-bound intermediates could lead to distinct, and potentially manipulable, dissociation pathways.
Data availability
Data used for Figures 2 to 7 is available in dryad.org
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Data from: Trans-toxin ion-sensitivity of charybdotoxin-blocked potassium-channels reveals unbinding transitional statesDryad Digital Repository, doi:10.5061/dryad.0p77qk4.
Article and author information
Author details
Funding
Fondo Nacional de Desarrollo Científico y Tecnológico (3160321)
- Hans Moldenhauer
Fondo Nacional de Desarrollo Científico y Tecnológico (3170599)
- Ignacio Díaz-Franulic
Fondo Nacional de Desarrollo Científico y Tecnológico (1171155)
- Horacio Poblete
Ministerio de Economía, Fomento y Turismo (MiNICAD)
- Horacio Poblete
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2019, Moldenhauer et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Trans-toxin ion-sensitivity of charybdotoxin-blocked potassium-channels reveals unbinding transitional states
eLife 8:e46170.
https://doi.org/10.7554/eLife.46170
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