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Conformational Ensembles from Experimental Data
and Computer Simulations
Poster Abstracts
125
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.