Voltage-gated K+ channels have distinct gates that regulate ion flux: the activation gate (A-gate) formed by the bundle crossing of the S6 transmembrane helices and the slow inactivation gate in the selectivity filter. These two gates are bidirectionally coupled. If coupling involves the rearrangement of the S6 transmembrane segment, then we predict state-dependent changes in the accessibility of S6 residues from the water-filled cavity of the channel with gating. To test this, we engineered cysteines, one at a time, at S6 positions A471, L472, and P473 in a T449A Shaker-IR background and determined the accessibility of these cysteines to cysteine-modifying reagents MTSET and MTSEA applied to the cytosolic surface of inside-out patches. We found that neither reagent modified either of the cysteines in the closed or the open state of the channels. On the contrary, A471C and P473C, but not L472C, were modified by MTSEA, but not by MTSET, if applied to inactivated channels with open A-gate (OI state). Our results, combined with earlier studies reporting reduced accessibility of residues I470C and V474C in the inactivated state, strongly suggest that the coupling between the A-gate and the slow inactivation gate is mediated by rearrangements in the S6 segment. The S6 rearrangements are consistent with a rigid rod-like rotation of S6 around its longitudinal axis upon inactivation. S6 rotation and changes in its environment are concomitant events in slow inactivation of Shaker KV channels.
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May 22 2023
Molecular rearrangements in S6 during slow inactivation in Shaker-IR potassium channels
Tibor G. Szanto
,
Tibor G. Szanto
(Conceptualization, Data curation, Formal analysis, Investigation, Validation, Visualization, Writing - original draft)
1Department of Biophysics and Cell Biology, Faculty of Medicine,
University of Debrecen
, Debrecen, Hungary
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Ferenc Papp
,
Ferenc Papp
(Formal analysis, Investigation)
1Department of Biophysics and Cell Biology, Faculty of Medicine,
University of Debrecen
, Debrecen, Hungary
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Florina Zakany
,
Florina Zakany
(Formal analysis, Investigation)
1Department of Biophysics and Cell Biology, Faculty of Medicine,
University of Debrecen
, Debrecen, Hungary
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Zoltan Varga
,
Zoltan Varga
(Conceptualization, Writing - review & editing)
1Department of Biophysics and Cell Biology, Faculty of Medicine,
University of Debrecen
, Debrecen, Hungary
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Carol Deutsch
,
Carol Deutsch
(Conceptualization, Methodology, Writing - review & editing)
2Department of Physiology,
University of Pennsylvania
, Philadelphia, PA, USA
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Gyorgy Panyi
(Conceptualization, Formal analysis, Funding acquisition, Methodology, Project administration, Resources, Supervision, Validation, Writing - original draft, Writing - review & editing)
1Department of Biophysics and Cell Biology, Faculty of Medicine,
University of Debrecen
, Debrecen, Hungary
Correspondence to Gyorgy Panyi: panyi@med.unideb.hu
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Tibor G. Szanto
Conceptualization, Data curation, Formal analysis, Investigation, Validation, Visualization, Writing - original draft
1Department of Biophysics and Cell Biology, Faculty of Medicine,
University of Debrecen
, Debrecen, Hungary
Ferenc Papp
Formal analysis, Investigation
1Department of Biophysics and Cell Biology, Faculty of Medicine,
University of Debrecen
, Debrecen, Hungary
Florina Zakany
Formal analysis, Investigation
1Department of Biophysics and Cell Biology, Faculty of Medicine,
University of Debrecen
, Debrecen, Hungary
Zoltan Varga
Conceptualization, Writing - review & editing
1Department of Biophysics and Cell Biology, Faculty of Medicine,
University of Debrecen
, Debrecen, Hungary
Carol Deutsch
Conceptualization, Methodology, Writing - review & editing
2Department of Physiology,
University of Pennsylvania
, Philadelphia, PA, USA
Gyorgy Panyi
Conceptualization, Formal analysis, Funding acquisition, Methodology, Project administration, Resources, Supervision, Validation, Writing - original draft, Writing - review & editing
1Department of Biophysics and Cell Biology, Faculty of Medicine,
University of Debrecen
, Debrecen, Hungary
Correspondence to Gyorgy Panyi: panyi@med.unideb.hu
The authors declare no competing interests exist.
Received:
January 29 2023
Revision Received:
April 14 2023
Accepted:
May 04 2023
Online ISSN: 1540-7748
Print ISSN: 0022-1295
Funding
Funder(s):
Hungarian Academy of Sciences
- Award Id(s): KTIA_NAP_13-2-2015-0009,KTIA_NAP_13-2-2017-0013
Funder(s):
National Research, Development, and Innovation Office
- Award Id(s): OTKA K132906,OTKA K143071
Funder(s):
Ministry of Human Capacities
- Award Id(s): EFOP-3.6.2-16-2017-00006
Funder(s):
Ministry of Finance, Hungary
- Award Id(s): GINOP-2.3.2-15-2016-00044
Funder(s):
National Institutes of Health
- Award Id(s): R01 GM052302
© 2023 Szanto et al.
2023
Szanto et al.
This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms/). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 International license, as described at https://creativecommons.org/licenses/by-nc-sa/4.0/).
J Gen Physiol (2023) 155 (7): e202313352.
Article history
Received:
January 29 2023
Revision Received:
April 14 2023
Accepted:
May 04 2023
Citation
Tibor G. Szanto, Ferenc Papp, Florina Zakany, Zoltan Varga, Carol Deutsch, Gyorgy Panyi; Molecular rearrangements in S6 during slow inactivation in Shaker-IR potassium channels. J Gen Physiol 3 July 2023; 155 (7): e202313352. doi: https://doi.org/10.1085/jgp.202313352
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