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Molecular and pharmacological characterization of an acetylcholine-gated chloride channel (ACC-2) from the parasitic nematode Haemonchus contortus

Nematode cys-loop ligand-gated ion channels (LGICs) have been shown to be attractive targets for the development of novel anti-parasitic drugs. The ACC-1 family of receptors are a unique group of acetylcholine-gated chloride channels present only in invertebrates, and sequence analysis suggests that...

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Autores principales: Habibi, Sarah A., Callanan, Micah, Forrester, Sean G.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Elsevier 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6287471/
https://www.ncbi.nlm.nih.gov/pubmed/30266440
http://dx.doi.org/10.1016/j.ijpddr.2018.09.004
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author Habibi, Sarah A.
Callanan, Micah
Forrester, Sean G.
author_facet Habibi, Sarah A.
Callanan, Micah
Forrester, Sean G.
author_sort Habibi, Sarah A.
collection PubMed
description Nematode cys-loop ligand-gated ion channels (LGICs) have been shown to be attractive targets for the development of novel anti-parasitic drugs. The ACC-1 family of receptors are a unique group of acetylcholine-gated chloride channels present only in invertebrates, and sequence analysis suggests that they contain a novel binding site for acetylcholine. We have isolated a novel member of this family, Hco-ACC-2, from the parasitic nematode Haemonchus contortus and using site-directed mutagenesis, electrophysiology and molecular modelling examined how two aromatic amino acids in the binding site contributed to agonist recognition. It was found that instead of a tryptophan residue in binding loop B, which essential for ligand binding in mammalian nAChRs, there is a phenylalanine (F200) in Hco-ACC-2. Amino acid changes at F200 to either a tyrosine or tryptophan were fairly well tolerated, where a F200Y mutation resulted in a channel hypersensitive to ACh and nicotine as well as other cholinergic agonists such as carbachol and methacholine. In addition, both pyrantel and levamisole were partial agonists at the wild-type receptor and like the other agonists showed an increase in sensitivity at F200Y. On the other hand, in Hco-ACC-2 there is a tryptophan residue at position 248 in loop C that appears to be essential for receptor function, as mutations to either phenylalanine or tyrosine resulted in a marked decrease in agonist sensitivity. Moreover, mutations that swapped the residues F200 and W248 (ie. F200W/W248F) produced non-functional receptors. Overall, Hco-ACC-2 appears to have a novel cholinergic binding site that could have implications for the design of specific anthelmintics that target this family of receptors in parasitic nematodes.
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spelling pubmed-62874712018-12-19 Molecular and pharmacological characterization of an acetylcholine-gated chloride channel (ACC-2) from the parasitic nematode Haemonchus contortus Habibi, Sarah A. Callanan, Micah Forrester, Sean G. Int J Parasitol Drugs Drug Resist Articles from the scientific meeting: "Anthelmintics: From Discovery to Resistance III", pp. 494 - 628. Nematode cys-loop ligand-gated ion channels (LGICs) have been shown to be attractive targets for the development of novel anti-parasitic drugs. The ACC-1 family of receptors are a unique group of acetylcholine-gated chloride channels present only in invertebrates, and sequence analysis suggests that they contain a novel binding site for acetylcholine. We have isolated a novel member of this family, Hco-ACC-2, from the parasitic nematode Haemonchus contortus and using site-directed mutagenesis, electrophysiology and molecular modelling examined how two aromatic amino acids in the binding site contributed to agonist recognition. It was found that instead of a tryptophan residue in binding loop B, which essential for ligand binding in mammalian nAChRs, there is a phenylalanine (F200) in Hco-ACC-2. Amino acid changes at F200 to either a tyrosine or tryptophan were fairly well tolerated, where a F200Y mutation resulted in a channel hypersensitive to ACh and nicotine as well as other cholinergic agonists such as carbachol and methacholine. In addition, both pyrantel and levamisole were partial agonists at the wild-type receptor and like the other agonists showed an increase in sensitivity at F200Y. On the other hand, in Hco-ACC-2 there is a tryptophan residue at position 248 in loop C that appears to be essential for receptor function, as mutations to either phenylalanine or tyrosine resulted in a marked decrease in agonist sensitivity. Moreover, mutations that swapped the residues F200 and W248 (ie. F200W/W248F) produced non-functional receptors. Overall, Hco-ACC-2 appears to have a novel cholinergic binding site that could have implications for the design of specific anthelmintics that target this family of receptors in parasitic nematodes. Elsevier 2018-09-22 /pmc/articles/PMC6287471/ /pubmed/30266440 http://dx.doi.org/10.1016/j.ijpddr.2018.09.004 Text en © 2018 The Authors http://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
spellingShingle Articles from the scientific meeting: "Anthelmintics: From Discovery to Resistance III", pp. 494 - 628.
Habibi, Sarah A.
Callanan, Micah
Forrester, Sean G.
Molecular and pharmacological characterization of an acetylcholine-gated chloride channel (ACC-2) from the parasitic nematode Haemonchus contortus
title Molecular and pharmacological characterization of an acetylcholine-gated chloride channel (ACC-2) from the parasitic nematode Haemonchus contortus
title_full Molecular and pharmacological characterization of an acetylcholine-gated chloride channel (ACC-2) from the parasitic nematode Haemonchus contortus
title_fullStr Molecular and pharmacological characterization of an acetylcholine-gated chloride channel (ACC-2) from the parasitic nematode Haemonchus contortus
title_full_unstemmed Molecular and pharmacological characterization of an acetylcholine-gated chloride channel (ACC-2) from the parasitic nematode Haemonchus contortus
title_short Molecular and pharmacological characterization of an acetylcholine-gated chloride channel (ACC-2) from the parasitic nematode Haemonchus contortus
title_sort molecular and pharmacological characterization of an acetylcholine-gated chloride channel (acc-2) from the parasitic nematode haemonchus contortus
topic Articles from the scientific meeting: "Anthelmintics: From Discovery to Resistance III", pp. 494 - 628.
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6287471/
https://www.ncbi.nlm.nih.gov/pubmed/30266440
http://dx.doi.org/10.1016/j.ijpddr.2018.09.004
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