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Estructura del dominio Rb C-terminal unido a E2F1-DP1: un mecanismo para la liberación de E2F inducida por
Seth M Rubin1, Anne-Laure Gall, Ning Zheng
1Structural Biology Program and Howard Hughes Medical Institute, Memorial Sloan-Kettering Cancer Center, NY 10021, USA.
Cell
|December 20, 2005
Resumen
La proteína del retinoblastoma (Rb) es una proteína
Área de la Ciencia:
- Regulación del ciclo celular Regulación del ciclo celular
- Biología molecular La biología molecular.
- Las interacciones proteína-proteína.
Sus antecedentes:
- La proteína del retinoblastoma (Rb) es un regulador clave de la transición de fase G1-S en el ciclo celular.
- Rb se une a los factores de transcripción E2F, inhibiendo su actividad hasta que se fosforila por las cinasas dependientes de la ciclina.
- Mientras que el dominio de bolsillo Rb media la unión E2F, el dominio C-terminal (RbC) también es crucial para la supresión del crecimiento.
Objetivo del estudio:
- Para aclarar la base estructural de la interacción entre el dominio Rb C-terminal (RbC) y los heterodímeros E2F-DP.
- Comprender el papel de RbC en la unión E2F de alta afinidad y la supresión del crecimiento.
- Investigar el mecanismo por el cual la fosforilación regula las interacciones Rb-E2F.
Principales métodos:
- Los ensayos de coinmunoprecipitación confirman las interacciones de las proteínas.
- Cristalografía de rayos X para determinar la estructura del complejo RbC-E2F1-DP1.
- Mutagénesis dirigida al sitio para estudiar los efectos de la fosforilación en la unión Rb-E2F.
Principales resultados:
- Se identificó una interacción de alta afinidad entre los heterodímeros RbC y E2F-DP.
- La estructura cristalina reveló un heterodimero entrelazado donde los dominios de caja marcados E2F1 y DP1 entran en contacto con RbC.
- Se demostró que la fosforilación de RbC en sitios específicos (Ser788/795 y Thr821/826) desestabiliza las interacciones Rb-E2F a través de mecanismos directos e indirectos.
Conclusiones:
- El dominio Rb C-terminal (RbC) es esencial para la unión de alta afinidad a los heterodímeros E2F-DP y contribuye a la supresión del crecimiento.
- La estructura cristalina proporciona una base molecular para la formación del complejo RbC-E2F-DP.
- La fosforilación de RbC actúa como un interruptor regulador, modulando la asociación Rb-E2F y controlando así la progresión del ciclo celular.
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