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Journal Article

Direct knock-on of desolvated ions governs strict ion selectivity in K+ channels.

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Kopec,  W.
Research Group of Computational Biomolecular Dynamics, MPI for biophysical chemistry, Max Planck Society;

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Köpfer,  D.
Research Group of Computational Biomolecular Dynamics, MPI for biophysical chemistry, Max Planck Society;

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de Groot,  B. L.
Research Group of Computational Biomolecular Dynamics, MPI for biophysical chemistry, Max Planck Society;

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Fulltext (public)

2627996.pdf
(Publisher version), 4MB

Supplementary Material (public)

2627996_Suppl.pdf
(Supplementary material), 38MB

Citation

Kopec, W., Köpfer, D., Vickery, O. N., Bondarenko, A. S., Jansen, T. L. C., de Groot, B. L., et al. (2018). Direct knock-on of desolvated ions governs strict ion selectivity in K+ channels. Nature Chemistry, 10(8), 813-820. doi:10.1038/s41557-018-0105-9.


Cite as: http://hdl.handle.net/21.11116/0000-0001-DB3B-7
Abstract
The seeming contradiction that K+ channels conduct K+ ions at maximal throughput rates while not permeating slightly smaller Na+ ions has perplexed scientists for decades. Although numerous models have addressed selective permeation in K+ channels, the combination of conduction efficiency and ion selectivity has not yet been linked through a unified functional model. Here, we investigate the mechanism of ion selectivity through atomistic simulations totalling more than 400 μs in length, which include over 7,000 permeation events. Together with free-energy calculations, our simulations show that both rapid permeation of K+ and ion selectivity are ultimately based on a single principle: the direct knock-on of completely desolvated ions in the channels' selectivity filter. Herein, the strong interactions between multiple 'naked' ions in the four filter binding sites give rise to a natural exclusion of any competing ions. Our results are in excellent agreement with experimental selectivity data, measured ion interaction energies and recent two-dimensional infrared spectra of filter ion configurations.