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Structural implications of hERG K(+) channel block by a high-affinity minimally structured blocker

Cardiac potassium channels encoded by human ether-à-go-go–related gene (hERG) are major targets for structurally diverse drugs associated with acquired long QT syndrome. This study characterized hERG channel inhibition by a minimally structured high-affinity hERG inhibitor, Cavalli-2, composed of th...

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Autores principales: Helliwell, Matthew V., Zhang, Yihong, El Harchi, Aziza, Du, Chunyun, Hancox, Jules C., Dempsey, Christopher E.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Society for Biochemistry and Molecular Biology 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5936838/
https://www.ncbi.nlm.nih.gov/pubmed/29545312
http://dx.doi.org/10.1074/jbc.RA117.000363
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author Helliwell, Matthew V.
Zhang, Yihong
El Harchi, Aziza
Du, Chunyun
Hancox, Jules C.
Dempsey, Christopher E.
author_facet Helliwell, Matthew V.
Zhang, Yihong
El Harchi, Aziza
Du, Chunyun
Hancox, Jules C.
Dempsey, Christopher E.
author_sort Helliwell, Matthew V.
collection PubMed
description Cardiac potassium channels encoded by human ether-à-go-go–related gene (hERG) are major targets for structurally diverse drugs associated with acquired long QT syndrome. This study characterized hERG channel inhibition by a minimally structured high-affinity hERG inhibitor, Cavalli-2, composed of three phenyl groups linked by polymethylene spacers around a central amino group, chosen to probe the spatial arrangement of side chain groups in the high-affinity drug-binding site of the hERG pore. hERG current (I(hERG)) recorded at physiological temperature from HEK293 cells was inhibited with an IC(50) of 35.6 nm with time and voltage dependence characteristic of blockade contingent upon channel gating. Potency of Cavalli-2 action was markedly reduced for attenuated inactivation mutants located near (S620T; 54-fold) and remote from (N588K; 15-fold) the channel pore. The S6 Y652A and F656A mutations decreased inhibitory potency 17- and 75-fold, respectively, whereas T623A and S624A at the base of the selectivity filter also decreased potency (16- and 7-fold, respectively). The S5 helix F557L mutation decreased potency 10-fold, and both F557L and Y652A mutations eliminated voltage dependence of inhibition. Computational docking using the recent cryo-EM structure of an open channel hERG construct could only partially recapitulate experimental data, and the high dependence of Cavalli-2 block on Phe-656 is not readily explainable in that structure. A small clockwise rotation of the inner (S6) helix of the hERG pore from its configuration in the cryo-EM structure may be required to optimize Phe-656 side chain orientations compatible with high-affinity block.
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spelling pubmed-59368382018-05-08 Structural implications of hERG K(+) channel block by a high-affinity minimally structured blocker Helliwell, Matthew V. Zhang, Yihong El Harchi, Aziza Du, Chunyun Hancox, Jules C. Dempsey, Christopher E. J Biol Chem Membrane Biology Cardiac potassium channels encoded by human ether-à-go-go–related gene (hERG) are major targets for structurally diverse drugs associated with acquired long QT syndrome. This study characterized hERG channel inhibition by a minimally structured high-affinity hERG inhibitor, Cavalli-2, composed of three phenyl groups linked by polymethylene spacers around a central amino group, chosen to probe the spatial arrangement of side chain groups in the high-affinity drug-binding site of the hERG pore. hERG current (I(hERG)) recorded at physiological temperature from HEK293 cells was inhibited with an IC(50) of 35.6 nm with time and voltage dependence characteristic of blockade contingent upon channel gating. Potency of Cavalli-2 action was markedly reduced for attenuated inactivation mutants located near (S620T; 54-fold) and remote from (N588K; 15-fold) the channel pore. The S6 Y652A and F656A mutations decreased inhibitory potency 17- and 75-fold, respectively, whereas T623A and S624A at the base of the selectivity filter also decreased potency (16- and 7-fold, respectively). The S5 helix F557L mutation decreased potency 10-fold, and both F557L and Y652A mutations eliminated voltage dependence of inhibition. Computational docking using the recent cryo-EM structure of an open channel hERG construct could only partially recapitulate experimental data, and the high dependence of Cavalli-2 block on Phe-656 is not readily explainable in that structure. A small clockwise rotation of the inner (S6) helix of the hERG pore from its configuration in the cryo-EM structure may be required to optimize Phe-656 side chain orientations compatible with high-affinity block. American Society for Biochemistry and Molecular Biology 2018-05-04 2018-03-15 /pmc/articles/PMC5936838/ /pubmed/29545312 http://dx.doi.org/10.1074/jbc.RA117.000363 Text en © 2018 by The American Society for Biochemistry and Molecular Biology, Inc. Author's Choice—Final version free via Creative Commons CC-BY license (http://creativecommons.org/licenses/by/4.0) .
spellingShingle Membrane Biology
Helliwell, Matthew V.
Zhang, Yihong
El Harchi, Aziza
Du, Chunyun
Hancox, Jules C.
Dempsey, Christopher E.
Structural implications of hERG K(+) channel block by a high-affinity minimally structured blocker
title Structural implications of hERG K(+) channel block by a high-affinity minimally structured blocker
title_full Structural implications of hERG K(+) channel block by a high-affinity minimally structured blocker
title_fullStr Structural implications of hERG K(+) channel block by a high-affinity minimally structured blocker
title_full_unstemmed Structural implications of hERG K(+) channel block by a high-affinity minimally structured blocker
title_short Structural implications of hERG K(+) channel block by a high-affinity minimally structured blocker
title_sort structural implications of herg k(+) channel block by a high-affinity minimally structured blocker
topic Membrane Biology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5936838/
https://www.ncbi.nlm.nih.gov/pubmed/29545312
http://dx.doi.org/10.1074/jbc.RA117.000363
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