Visualizing KcsA Conformational Changes upon Ion Binding by Infrared Spectroscopy and Atomistic Modeling
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Stevenson-2015-Visualizing KcsA.pdf
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Author(s)
Stevenson, Paul
Baiz, Carlos R.
Akerboom, Jasper
Tokmakoff, Andrei
Vaziri, Alipasha
Gotz, Christoph
Date Issued
April 2015
Journal
The Journal of Physical Chemistry B
Publisher
American Chemical Society (ACS)
Citation
Stevenson, Paul, Christoph Gotz, Carlos R. Baiz, Jasper Akerboom, Andrei Tokmakoff, and Alipasha Vaziri. “Visualizing KcsA Conformational Changes Upon Ion Binding by Infrared Spectroscopy and Atomistic Modeling.” The Journal of Physical Chemistry B 119, no. 18 (May 7, 2015): 5824–5831. © 2015 American Chemical Society
Version
Final published version
Abstract
The effect of ion binding in the selectivity filter of the potassium channel KcsA is investigated by combining amide I Fourier-transform infrared spectroscopy with structure-based spectral modeling. Experimental difference IR spectra between K[superscript +]-bound KcsA and Na[superscript +]-bound KcsA are in good qualitative agreement with spectra modeled from structural ensembles generated from molecular dynamics simulations. The molecular origins of the vibrational modes contributing to differences in these spectra are determined not only from structural differences in the selectivity filter but also from the pore helices surrounding this region. Furthermore, the coordination of K[superscript +] or Na[superscript +] to carbonyls in the selectivity filter effectively decouples the vibrations of those carbonyls from the rest of the protein, creating local probes of the electrostatic environment. The results suggest that it is necessary to include the influence of the surrounding helices in discussing selectivity and transport in KcsA and, on a more general level, that IR spectroscopy offers a nonperturbative route to studying the structure and dynamics of ion channels.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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DOI of Published Version
https://doi.org/10.1021/acs.jpcb.5b02223
