Instantaneous ion configurations in the K+ion channel selectivity filter revealed by 2D IR spectroscopy

Huong T. Kratochvil, Joshua K. Carr, Kimberly Matulef, Alvin W. Annen, Hui Li, Michał Maj, Jared Ostmeyer, Arnaldo L. Serrano, H. Raghuraman, Sean D. Moran, J. L. Skinner, Eduardo Perozo, Benoît Roux, Francis Valiyaveetil, Martin T. Zanni

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Abstract

Potassium channels are responsible for the selective permeation of K ions across cell membranes. K+ ions permeate in single file through the selectivity filter, a narrow pore lined by backbone carbonyls that compose four K+ binding sites Here we report on the two-dimensional infrared (2D IR) spectra of a semisynthetic KcsA channel with sitespecific heavy (13C18O) isotope labels in the selectivity filter The ultrafast time resolution of 2D IR spectroscopy provides an instantaneous snapshot of the multi-ion configurations and structural distributions that occur spontaneously in the filter Two elongated features are resolved revealing the statistical weighting of two structural conformations The spectra are reproduced by molecular dynamics simulations of structures with water separating two K+ions in the binding sites ruling out configurations with ions occupying adjacent sites.

Original languageEnglish (US)
Pages (from-to)1040-1044
Number of pages5
JournalScience
Volume353
Issue number6303
DOIs
StatePublished - Sep 2 2016

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ASJC Scopus subject areas

  • Medicine(all)
  • General

Cite this

Kratochvil, H. T., Carr, J. K., Matulef, K., Annen, A. W., Li, H., Maj, M., Ostmeyer, J., Serrano, A. L., Raghuraman, H., Moran, S. D., Skinner, J. L., Perozo, E., Roux, B., Valiyaveetil, F., & Zanni, M. T. (2016). Instantaneous ion configurations in the K+ion channel selectivity filter revealed by 2D IR spectroscopy. Science, 353(6303), 1040-1044. https://doi.org/10.1126/science.aag1447