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Acoplamiento electromecánico en el canal KAT1 activado por hiperpolarización
Michael David Clark1, Gustavo F Contreras1, Rong Shen1
1Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA.
Nature
|May 29, 2020
Resumen
Los investigadores aclararon el mecanismo de polaridad de la puerta en los canales de potasio (Kv) con tensión utilizando la estructura KAT1. Las interacciones directas entre los sensores y los poros, no la alostería, determinan principalmente la dirección de la puerta del canal.
Área de la Ciencia:
- Biología molecular
- La biofísica
- Biología estructural
Sus antecedentes:
- Los canales de potasio regulados por voltaje (Kv) son cruciales para la señalización eléctrica y la regulación del volumen celular.
- Mientras que los sensores de voltaje transducen campos eléctricos, los determinantes de la polaridad de entrada del canal Kv no se comprenden completamente.
Objetivo del estudio:
- Para dilucidar el mecanismo molecular del acoplamiento electromecánico y la polaridad de la puerta en canales Kv sin intercambio de dominio.
- Determinar la base estructural para la activación de la hiperpolarización en el canal KAT1.
Principales métodos:
- Microscopía criolectrónica para determinar la estructura del canal KAT1.
- Mutagenesis guiada por la estructura y electrofisiología funcional para evaluar la actividad del canal mutante.
Principales resultados:
- La estructura de KAT1 reveló un sensor de voltaje despolarizado que interactúa con un dominio de poro cerrado a través de interfaces directas e indirectas.
- El análisis mutacional identificó las interacciones directas entre el sensor de voltaje y la horquilla de enlace C como el determinante principal de la polaridad de la puerta.
- Se propuso un mecanismo de acoplamiento directo que involucra el movimiento de la hélice S4 y la reorientación del enlace C.
Conclusiones:
- Las interacciones directas sensor-poro, específicamente entre el sensor de voltaje y la subunidad de poro adyacente C-linker, dictan la polaridad de entrada del canal Kv.
- Este mecanismo de acoplamiento directo ofrece una nueva perspectiva que contrasta con los modelos alostéricos y puede vincular los canales activados por despolarización e hiperpolarización.
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