Conformational Ensembles from Experimental Data and Computer Simulations

Conformational Ensembles from Experimental Data and Computer Simulations

Poster Abstracts

88-POS Board 8 Correlating Ion Occupation and Voltage-Dependent Selectivity Filter Gating Obtained from Functional Data of a K + Channel Oliver Rauh 1 , Ulf-Peter Hansen 2 , Gerhard Thiel 1 , Indra Schroeder 1 . 1 Technical University of Darmstadt, Darmstadt, Germany, 2 Christian-Albrechts-University of Kiel, Kiel, Germany. The conformational transition between conducting and non-conducting states (“gating”) in the selectivity filter of potassium channels is influenced by the occupation of the ion binding sites inside the filter. This has been shown by numerous functional, structural and computational studies (e.g.1–3). However, which of the structural findings applies to which electrophysiological observation is not always clear. Here, we show that classical kinetic modelling – when based on current structural knowledge - is able to provide a bridge between structural/computational data and electrophysiology. The viral K + channel Kcv NTS served a model system(4). It closely resembles the pore domain of more complex K + channels in structure and function and shows a fast, strongly voltage- dependent gating process at negative membrane potentials. Channels were expressed in vitro and reconstituted into planar lipid bilayers.Because the voltage-dependent gating process is faster than the temporal resolution of bilayer experiments, extended beta distribution analysis(5) was employed to determine the open channel current and the rate constants of gating. From current structural knowledge, a kinetic model for the ion flux was derived and fitted to the single-channel IV curves. Specific states within the conduction cycle could be correlated with the voltage-dependent rate of channel closing of Kcv NTS . References: (1) Zhou, Y. et al.. Nature 2001, 414 (6859), 43–48. (2) Bernèche, S.; Roux, B. Structure 2005, 13 (4), 591–600. (3) Schewe, M. et al.. Cell 2016, 164 (5), 937–949. (4) Rauh, O. et al. J. Am. Chem. Soc. 2017, epub ahead of print. (5) Schroeder, I. Channels 2015, 9 (5), 262–280.

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