: Cyclic nucleotide-gated (CNG) ion channels, despite a significant homology with the highly selective K(+) channels, do not discriminate among monovalent alkali cations and are permeable also to several organic cations. We combined electrophysiology, molecular dynamics (MD) simulations, and X-ray crystallography to demonstrate that the pore of CNG channels is highly flexible. When a CNG mimic is crystallized in the presence of a variety of monovalent cations, including Na(+), Cs(+), and dimethylammonium (DMA(+)), the side chain of Glu66 in the selectivity filter shows multiple conformations and the diameter of the pore changes significantly. MD simulations indicate that Glu66 and the prolines in the outer vestibule undergo large fluctuations, which are modulated by the ionic species and the voltage. This flexibility underlies the coupling between gating and permeation and the poor ionic selectivity of CNG channels.

A structural, functional, and computational analysis suggests pore flexibility as the base for the poor selectivity of CNG channels / Napolitano, Luisa Maria Rosaria; Bisha, Ina; De March, Matteo; Marchesi, Arin; Arcangeletti, Manuel; Demitri, Nicola; Mazzolini, Monica; Rodriguez, Alex; Magistrato, Alessandra; Onesti, Silvia; Laio, Alessandro; Torre, Vincent. - In: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA. - ISSN 1091-6490. - 112:27(2015), p. E3619-28. [10.1073/pnas.1503334112]

A structural, functional, and computational analysis suggests pore flexibility as the base for the poor selectivity of CNG channels

Marchesi, Arin;
2015-01-01

Abstract

: Cyclic nucleotide-gated (CNG) ion channels, despite a significant homology with the highly selective K(+) channels, do not discriminate among monovalent alkali cations and are permeable also to several organic cations. We combined electrophysiology, molecular dynamics (MD) simulations, and X-ray crystallography to demonstrate that the pore of CNG channels is highly flexible. When a CNG mimic is crystallized in the presence of a variety of monovalent cations, including Na(+), Cs(+), and dimethylammonium (DMA(+)), the side chain of Glu66 in the selectivity filter shows multiple conformations and the diameter of the pore changes significantly. MD simulations indicate that Glu66 and the prolines in the outer vestibule undergo large fluctuations, which are modulated by the ionic species and the voltage. This flexibility underlies the coupling between gating and permeation and the poor ionic selectivity of CNG channels.
2015
CNG channels; MD simulations; X-ray crystallography; pore flexibility; Amino Acid Sequence; Animals; Bacterial Proteins; Cations, Monovalent; Cattle; Cesium; Crystallography, X-Ray; Cyclic Nucleotide-Gated Cation Channels; Female; Ion Channel Gating; Ion Transport; Membrane Potentials; Molecular Dynamics Simulation; Molecular Sequence Data; Mutant Proteins; Mutation, Missense; Oocytes; Patch-Clamp Techniques; Sequence Homology, Amino Acid; Sodium; Xenopus laevis; Protein Conformation
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11566/296853
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