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Crio-EM con resolución temporal de la activación de la proteína G por un GPCR

Makaía M Papasergi-Scott¹, Guillermo Pérez-Hernández², Hossein Batebi³

¹Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA.

|March 14, 2024

Resumen

Los investigadores visualizaron la activación del receptor acoplado a la proteína G (GPCR) utilizando cryo-EM con resolución en el tiempo. Este método reveló los cambios conformacionales en las proteínas G, detallando su disociación de los receptores después de la unión con GTP.

Área de la Ciencia:

Biología estructural
La bioquímica
Farmacología molecular

Sus antecedentes:

Los receptores acoplados a proteínas G (GPCR) son receptores cruciales de la superficie celular involucrados en numerosos procesos fisiológicos.
Los GPCR activan las proteínas G heterotriméricas, iniciando cascadas de señalización intracelular.
Comprender el mecanismo dinámico de la interacción de la proteína GPCR-G es esencial para el desarrollo de medicamentos.

Objetivo del estudio:

Visualizar los cambios conformacionales dinámicos durante la activación de la proteína G por los GPCR.
Para aclarar los eventos secuenciales que conducen a la disociación de la proteína G del receptor.
Establecer cryo-EM con resolución temporal como una herramienta poderosa para el estudio de los intermediarios de señalización GPCR.

Principales métodos:

Desarrollo y aplicación de un enfoque de crio-electrónica con resolución de tiempo (cryo-EM).
Análisis de los intermediarios del estado pre-estacionario de la proteína Gs compleja con el receptor β2-adrenérgico.
Generación de veinte estructuras de alta resolución en puntos de tiempo secuenciales después de la adición de GTP.
Simulaciones dinámicas moleculares complementarias para apoyar los cambios estructurales observados.

Principales resultados:

Identificó la trayectoria conformacional de la activación de la proteína Gs y la disociación del receptor.
Detallado el orden de los eventos clave, incluyendo los cambios estructurales que se propagan desde la bolsa de unión de nucleótidos.
Se han detectado alteraciones en las regiones del interruptor Gα y en la hélice α5 que debilitan la interfaz de la proteína GPCR-G.
Se ha demostrado una correlación entre el ordenamiento de GTP, el cierre del dominio y la disociación de la proteína G.

Conclusiones:

Proporcionó una vista de alta resolución y resolución temporal del mecanismo de activación de la proteína G.
Destacó el papel de los reordenamientos estructurales específicos en la facilitación de la disociación de la proteína G.
Crio-EM con resolución temporal validada como una técnica valiosa para diseccionar eventos de señalización dinámica.

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