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La recuperación de la inactivación lenta en los canales K+ está controlada por las moléculas de agua
Jared Ostmeyer1, Sudha Chakrapani, Albert C Pan
1Department of Biochemistry and Molecular Biology, The University of Chicago, 929 E57th Street, Chicago, Illinois 60637, USA.
Nature
|July 30, 2013
Resumen
Las moléculas de agua enterradas bloquean estéricamente los canales de potasio (K +) en un estado no conductor. La liberación de estas moléculas de agua, como se muestra en las simulaciones del canal KcsA, explica la recuperación lenta y puede acelerarse por el estrés osmótico.
Área de la Ciencia:
- La biofísica es la biofísica.
- Biología Estructural Biología estructural.
- Fisiología del canal iónico Fisiología del canal iónico
Sus antecedentes:
- Los canales de potasio (K +) regulan el transporte de iones a través de las membranas celulares, cruciales para las funciones celulares.
- Los mecanismos de inactivación y recuperación de canales siguen siendo incompletamente comprendidos a nivel atómico.
- El canal KcsA bacteriano proporciona un sistema modelo para el estudio de estos procesos sin dominios de detección de voltaje.
Objetivo del estudio:
- Para dilucidar los mecanismos a nivel atómico que subyacen a la lenta recuperación de la inactivación del canal K+.
- Investigar el papel de las moléculas internas de agua en el mantenimiento del estado inactivado del canal KcsA.
- Desarrollar un modelo cinético que explique la escala de tiempo de la recuperación del canal K+.
Principales métodos:
- Simulaciones de dinámica molecular larga del canal KcsA.
- Cálculos potenciales de fuerza media (PMF) para evaluar paisajes energéticos.
- Modelado cinético basado en datos de simulación.
- Verificación experimental utilizando el estrés osmótico (2 M sacarosa).
Principales resultados:
- Se identificaron moléculas de agua enterradas que obstaculizan estéricamente el filtro de selectividad en estado inactivado.
- Se demostró que la liberación de estas moléculas de agua es un factor clave en el lento proceso de recuperación.
- Los cálculos de PMF revelaron la influencia de las moléculas de agua y los iones K + externos en la cinética de recuperación.
- Las simulaciones predijeron que la reducción de la ocupación del agua acelera la recuperación.
Conclusiones:
- Las moléculas de agua enterradas juegan un papel crítico en el bloqueo estérico del canal KcsA en su conformación inactivada.
- La liberación de estas moléculas de agua dicta la lenta escala de tiempo de varios segundos de recuperación del canal.
- El estrés osmótico validó experimentalmente los hallazgos de la simulación acelerando las tasas de recuperación.
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