Mechanism of voltage sensing in Ca2+- and voltage-activated K+ (BK) channels

Willy Carrasquel-Ursulaez, Ignacio Segura, Ignacio Díaz-Franulic, Felipe Echeverría, Yenisleidy Lorenzo-Ceballos, Nicolás Espinoza, Maximiliano Rojas, Jose Antonio Garate, Eduardo Perozo, Osvaldo Alvarez, Fernando D. Gonzalez-Nilo, Ramón Latorre

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Resumen

In neurosecretion, allosteric communication between voltage sensors and Ca2+ binding in BK channels is crucially involved in damping excitatory stimuli. Nevertheless, the voltage-sensing mechanism of BK channels is still under debate. Here, based on gating current measurements, we demonstrate that two arginines in the transmembrane segment S4 (R210 and R213) function as the BK gating charges. Significantly, the energy landscape of the gating particles is electrostatically tuned by a network of salt bridges contained in the voltage sensor domain (VSD). Molecular dynamics simulations and proton transport experiments in the hyperpolarization-activated R210H mutant suggest that the electric field drops off within a narrow septum whose boundaries are defined by the gating charges. Unlike Kv channels, the charge movement in BK appears to be limited to a small displacement of the guanidinium moieties of R210 and R213, without significant movement of the S4.

Idioma originalInglés
Número de artículoe2204620119
PublicaciónProceedings of the National Academy of Sciences of the United States of America
Volumen119
N.º25
DOI
EstadoPublicada - 21 jun. 2022

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