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Determinants of ligand selectivity in a cyclic nucleotide–regulated potassium channel

Cyclic nucleotide–binding (CNB) domains regulate the activity of channels, kinases, exchange factors, and transcription factors. These proteins are highly variable in their ligand selectivity; some are highly selective for either cAMP or cGMP, whereas others are not. Several molecular determinants o...

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Autores principales: Pessoa, João, Fonseca, Fátima, Furini, Simone, Morais-Cabral, João H.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Rockefeller University Press 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4076524/
https://www.ncbi.nlm.nih.gov/pubmed/24981229
http://dx.doi.org/10.1085/jgp.201311145
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author Pessoa, João
Fonseca, Fátima
Furini, Simone
Morais-Cabral, João H.
author_facet Pessoa, João
Fonseca, Fátima
Furini, Simone
Morais-Cabral, João H.
author_sort Pessoa, João
collection PubMed
description Cyclic nucleotide–binding (CNB) domains regulate the activity of channels, kinases, exchange factors, and transcription factors. These proteins are highly variable in their ligand selectivity; some are highly selective for either cAMP or cGMP, whereas others are not. Several molecular determinants of ligand selectivity in CNB domains have been defined, but these do not provide a complete view of the selectivity mechanism. We performed a thorough analysis of the ligand-binding properties of mutants of the CNB domain from the MlotiK1 potassium channel. In particular, we defined which residues specifically favor cGMP or cAMP. Inversion of ligand selectivity, from favoring cAMP to favoring cGMP, was only achieved through a combination of three mutations in the ligand-binding pocket. We determined the x-ray structure of the triple mutant bound to cGMP and performed molecular dynamics simulations and a biochemical analysis of the effect of the mutations. We concluded that the increase in cGMP affinity and selectivity does not result simply from direct interactions between the nucleotide base and the amino acids introduced in the ligand-binding pocket residues. Rather, tighter cGMP binding over cAMP results from the polar chemical character of the mutations, from greater accessibility of water molecules to the ligand in the bound state, and from an increase in the structural flexibility of the mutated binding pocket.
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spelling pubmed-40765242015-01-01 Determinants of ligand selectivity in a cyclic nucleotide–regulated potassium channel Pessoa, João Fonseca, Fátima Furini, Simone Morais-Cabral, João H. J Gen Physiol Research Articles Cyclic nucleotide–binding (CNB) domains regulate the activity of channels, kinases, exchange factors, and transcription factors. These proteins are highly variable in their ligand selectivity; some are highly selective for either cAMP or cGMP, whereas others are not. Several molecular determinants of ligand selectivity in CNB domains have been defined, but these do not provide a complete view of the selectivity mechanism. We performed a thorough analysis of the ligand-binding properties of mutants of the CNB domain from the MlotiK1 potassium channel. In particular, we defined which residues specifically favor cGMP or cAMP. Inversion of ligand selectivity, from favoring cAMP to favoring cGMP, was only achieved through a combination of three mutations in the ligand-binding pocket. We determined the x-ray structure of the triple mutant bound to cGMP and performed molecular dynamics simulations and a biochemical analysis of the effect of the mutations. We concluded that the increase in cGMP affinity and selectivity does not result simply from direct interactions between the nucleotide base and the amino acids introduced in the ligand-binding pocket residues. Rather, tighter cGMP binding over cAMP results from the polar chemical character of the mutations, from greater accessibility of water molecules to the ligand in the bound state, and from an increase in the structural flexibility of the mutated binding pocket. The Rockefeller University Press 2014-07 /pmc/articles/PMC4076524/ /pubmed/24981229 http://dx.doi.org/10.1085/jgp.201311145 Text en © 2014 Pessoa 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 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/).
spellingShingle Research Articles
Pessoa, João
Fonseca, Fátima
Furini, Simone
Morais-Cabral, João H.
Determinants of ligand selectivity in a cyclic nucleotide–regulated potassium channel
title Determinants of ligand selectivity in a cyclic nucleotide–regulated potassium channel
title_full Determinants of ligand selectivity in a cyclic nucleotide–regulated potassium channel
title_fullStr Determinants of ligand selectivity in a cyclic nucleotide–regulated potassium channel
title_full_unstemmed Determinants of ligand selectivity in a cyclic nucleotide–regulated potassium channel
title_short Determinants of ligand selectivity in a cyclic nucleotide–regulated potassium channel
title_sort determinants of ligand selectivity in a cyclic nucleotide–regulated potassium channel
topic Research Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4076524/
https://www.ncbi.nlm.nih.gov/pubmed/24981229
http://dx.doi.org/10.1085/jgp.201311145
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