Hydrophobic interaction between contiguous residues in the S6 transmembrane segment acts as a stimuli integration node in the BK channel

Willy Carrasquel-Ursulaez, Gustavo F. Contreras, Romina V. Sepúlveda, Daniel Aguayo, Fernando González-Nilo, Carlos González, Ramón Latorre

Resultado de la investigación: Article

9 Citas (Scopus)

Resumen

Large-conductance Ca2+- and voltage-activated K+ channel (BK) open probability is enhanced by depolarization, increasing Ca2+ concentration, or both. These stimuli activate modular voltage and Ca2+ sensors that are allosterically coupled to channel gating. Here, we report a point mutation of a phenylalanine (F380A) in the S6 transmembrane helix that, in the absence of internal Ca2+, profoundly hinders channel opening while showing only minor effects on the voltage sensor active-resting equilibrium. Interpretation of these results using an allosteric model suggests that the F380A mutation greatly increases the free energy difference between open and closed states and uncouples Ca2+ binding from voltage sensor activation and voltage sensor activation from channel opening. However, the presence of a bulky and more hydrophobic amino acid in the F380 position (F380W) increases the intrinsic open-closed equilibrium, weakening the coupling between both sensors with the pore domain. Based on these functional experiments and molecular dynamics simulations, we propose tat F380 interacts with another S6 hydrophobic residue (L377) in contiguous subunits. This pair forms a hydrophobic ring important in determining the open-closed equilibrium and, like an integration node, participates in the communication between sensors and between the sensors and pore. Moreover, because of its effects on open probabilities, the F380A mutant can be used for detailed voltage sensor experiments in the presence of permeant cations.

Idioma originalEnglish
Páginas (desde-hasta)61-74
Número de páginas14
PublicaciónJournal of General Physiology
Volumen145
N.º1
DOI
EstadoPublished - 1 ene 2015

Huella dactilar

Large-Conductance Calcium-Activated Potassium Channels
S 6
Hydrophobic and Hydrophilic Interactions
Calcium-Activated Potassium Channels
Molecular Dynamics Simulation
Phenylalanine
Point Mutation
Cations
Amino Acids
Mutation

ASJC Scopus subject areas

  • Physiology

Citar esto

Carrasquel-Ursulaez, Willy ; Contreras, Gustavo F. ; Sepúlveda, Romina V. ; Aguayo, Daniel ; González-Nilo, Fernando ; González, Carlos ; Latorre, Ramón. / Hydrophobic interaction between contiguous residues in the S6 transmembrane segment acts as a stimuli integration node in the BK channel. En: Journal of General Physiology. 2015 ; Vol. 145, N.º 1. pp. 61-74.
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abstract = "Large-conductance Ca2+- and voltage-activated K+ channel (BK) open probability is enhanced by depolarization, increasing Ca2+ concentration, or both. These stimuli activate modular voltage and Ca2+ sensors that are allosterically coupled to channel gating. Here, we report a point mutation of a phenylalanine (F380A) in the S6 transmembrane helix that, in the absence of internal Ca2+, profoundly hinders channel opening while showing only minor effects on the voltage sensor active-resting equilibrium. Interpretation of these results using an allosteric model suggests that the F380A mutation greatly increases the free energy difference between open and closed states and uncouples Ca2+ binding from voltage sensor activation and voltage sensor activation from channel opening. However, the presence of a bulky and more hydrophobic amino acid in the F380 position (F380W) increases the intrinsic open-closed equilibrium, weakening the coupling between both sensors with the pore domain. Based on these functional experiments and molecular dynamics simulations, we propose tat F380 interacts with another S6 hydrophobic residue (L377) in contiguous subunits. This pair forms a hydrophobic ring important in determining the open-closed equilibrium and, like an integration node, participates in the communication between sensors and between the sensors and pore. Moreover, because of its effects on open probabilities, the F380A mutant can be used for detailed voltage sensor experiments in the presence of permeant cations.",
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Hydrophobic interaction between contiguous residues in the S6 transmembrane segment acts as a stimuli integration node in the BK channel. / Carrasquel-Ursulaez, Willy; Contreras, Gustavo F.; Sepúlveda, Romina V.; Aguayo, Daniel; González-Nilo, Fernando; González, Carlos; Latorre, Ramón.

En: Journal of General Physiology, Vol. 145, N.º 1, 01.01.2015, p. 61-74.

Resultado de la investigación: Article

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T1 - Hydrophobic interaction between contiguous residues in the S6 transmembrane segment acts as a stimuli integration node in the BK channel

AU - Carrasquel-Ursulaez, Willy

AU - Contreras, Gustavo F.

AU - Sepúlveda, Romina V.

AU - Aguayo, Daniel

AU - González-Nilo, Fernando

AU - González, Carlos

AU - Latorre, Ramón

PY - 2015/1/1

Y1 - 2015/1/1

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AB - Large-conductance Ca2+- and voltage-activated K+ channel (BK) open probability is enhanced by depolarization, increasing Ca2+ concentration, or both. These stimuli activate modular voltage and Ca2+ sensors that are allosterically coupled to channel gating. Here, we report a point mutation of a phenylalanine (F380A) in the S6 transmembrane helix that, in the absence of internal Ca2+, profoundly hinders channel opening while showing only minor effects on the voltage sensor active-resting equilibrium. Interpretation of these results using an allosteric model suggests that the F380A mutation greatly increases the free energy difference between open and closed states and uncouples Ca2+ binding from voltage sensor activation and voltage sensor activation from channel opening. However, the presence of a bulky and more hydrophobic amino acid in the F380 position (F380W) increases the intrinsic open-closed equilibrium, weakening the coupling between both sensors with the pore domain. Based on these functional experiments and molecular dynamics simulations, we propose tat F380 interacts with another S6 hydrophobic residue (L377) in contiguous subunits. This pair forms a hydrophobic ring important in determining the open-closed equilibrium and, like an integration node, participates in the communication between sensors and between the sensors and pore. Moreover, because of its effects on open probabilities, the F380A mutant can be used for detailed voltage sensor experiments in the presence of permeant cations.

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