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Molecular basis of inhibition of acid sensing ion channel 1A by diminazene
Acid-sensing ion channels (ASICs) are trimeric proton-gated cation permeable ion channels expressed primarily in neurons. Here we employed site-directed mutagenesis and electrophysiology to investigate the mechanism of inhibition of ASIC1a by diminazene. This compound inhibits mouse ASIC1a with a ha...
Autores principales: | , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Public Library of Science
2018
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5962070/ https://www.ncbi.nlm.nih.gov/pubmed/29782492 http://dx.doi.org/10.1371/journal.pone.0196894 |
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author | Krauson, Aram J. Rooney, James G. Carattino, Marcelo D. |
author_facet | Krauson, Aram J. Rooney, James G. Carattino, Marcelo D. |
author_sort | Krauson, Aram J. |
collection | PubMed |
description | Acid-sensing ion channels (ASICs) are trimeric proton-gated cation permeable ion channels expressed primarily in neurons. Here we employed site-directed mutagenesis and electrophysiology to investigate the mechanism of inhibition of ASIC1a by diminazene. This compound inhibits mouse ASIC1a with a half-maximal inhibitory concentration (IC(50)) of 2.4 μM. At first, we examined whether neutralizing mutations of Glu79 and Glu416 alter diminazene block. These residues form a hexagonal array in the lower palm domain that was previously shown to contribute to pore opening in response to extracellular acidification. Significantly, single Gln substitutions at positions 79 and 416 in ASIC1a reduced diminazene apparent affinity by 6–7 fold. This result suggests that diminazene inhibits ASIC1a in part by limiting conformational rearrangement in the lower palm domain. Because diminazene is charged at physiological pHs, we assessed whether it inhibits ASIC1a by blocking the ion channel pore. Consistent with the notion that diminazene binds to a site within the membrane electric field, diminazene block showed a strong dependence with the membrane potential. Moreover, a Gly to Ala mutation at position 438, in the ion conduction pathway of ASIC1a, increased diminazene IC(50) by one order of magnitude and eliminated the voltage dependence of block. Taken together, our results indicate that the inhibition of ASIC1a by diminazene involves both allosteric modulation and blocking of ion flow through the conduction pathway. Our findings provide a foundation for the development of more selective and potent ASIC pore blockers. |
format | Online Article Text |
id | pubmed-5962070 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2018 |
publisher | Public Library of Science |
record_format | MEDLINE/PubMed |
spelling | pubmed-59620702018-06-02 Molecular basis of inhibition of acid sensing ion channel 1A by diminazene Krauson, Aram J. Rooney, James G. Carattino, Marcelo D. PLoS One Research Article Acid-sensing ion channels (ASICs) are trimeric proton-gated cation permeable ion channels expressed primarily in neurons. Here we employed site-directed mutagenesis and electrophysiology to investigate the mechanism of inhibition of ASIC1a by diminazene. This compound inhibits mouse ASIC1a with a half-maximal inhibitory concentration (IC(50)) of 2.4 μM. At first, we examined whether neutralizing mutations of Glu79 and Glu416 alter diminazene block. These residues form a hexagonal array in the lower palm domain that was previously shown to contribute to pore opening in response to extracellular acidification. Significantly, single Gln substitutions at positions 79 and 416 in ASIC1a reduced diminazene apparent affinity by 6–7 fold. This result suggests that diminazene inhibits ASIC1a in part by limiting conformational rearrangement in the lower palm domain. Because diminazene is charged at physiological pHs, we assessed whether it inhibits ASIC1a by blocking the ion channel pore. Consistent with the notion that diminazene binds to a site within the membrane electric field, diminazene block showed a strong dependence with the membrane potential. Moreover, a Gly to Ala mutation at position 438, in the ion conduction pathway of ASIC1a, increased diminazene IC(50) by one order of magnitude and eliminated the voltage dependence of block. Taken together, our results indicate that the inhibition of ASIC1a by diminazene involves both allosteric modulation and blocking of ion flow through the conduction pathway. Our findings provide a foundation for the development of more selective and potent ASIC pore blockers. Public Library of Science 2018-05-21 /pmc/articles/PMC5962070/ /pubmed/29782492 http://dx.doi.org/10.1371/journal.pone.0196894 Text en © 2018 Krauson et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. |
spellingShingle | Research Article Krauson, Aram J. Rooney, James G. Carattino, Marcelo D. Molecular basis of inhibition of acid sensing ion channel 1A by diminazene |
title | Molecular basis of inhibition of acid sensing ion channel 1A by diminazene |
title_full | Molecular basis of inhibition of acid sensing ion channel 1A by diminazene |
title_fullStr | Molecular basis of inhibition of acid sensing ion channel 1A by diminazene |
title_full_unstemmed | Molecular basis of inhibition of acid sensing ion channel 1A by diminazene |
title_short | Molecular basis of inhibition of acid sensing ion channel 1A by diminazene |
title_sort | molecular basis of inhibition of acid sensing ion channel 1a by diminazene |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5962070/ https://www.ncbi.nlm.nih.gov/pubmed/29782492 http://dx.doi.org/10.1371/journal.pone.0196894 |
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