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RhoC GTPase Activation Assay
Published on: August 22, 2010
Estructura a 1,65 A de RhoA y su proteína activadora de la GTPasa en complejo con un análogo de estado de transición
K Rittinger1, P A Walker, J F Eccleston
1National Institute for Medical Research, London, UK.
Nature
|October 24, 1997
Resumen
Las pequeñas proteínas G como la RhoA regulan las funciones celulares cambiando entre los estados GTP y GDP. RhoGAP acelera la hidrólisis de GTP, con su residuo Arg85 estabilizando el estado de transición para la actividad de la GTPasa.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- Biología Estructural Biología estructural.
- La bioquímica es la bioquímica.
Sus antecedentes:
- Las pequeñas proteínas G de la familia Rho (Rho, Rac, Cdc42Hs) son reguladores clave de los procesos celulares.
- Estas proteínas funcionan como interruptores moleculares, que se mueven entre estados activos ligados al GTP e inactivos ligados al PIB.
- La hidrólisis de GTP por las proteínas Rho es lenta pero significativamente acelerada por las proteínas activadoras de la GTPasa (GAP), como rhoGAP.
Objetivo del estudio:
- Para determinar la estructura cristalina del complejo RhoA y rhoGAP.
- Para dilucidar el mecanismo por el cual rhoGAP estimula la hidrólisis de GTP en las proteínas Rho.
- Investigar las bases estructurales para la estabilización del estado de transición durante la actividad de la fase GTP.
Principales métodos:
- Se utilizó la cristalografía de rayos X para obtener la estructura del complejo RhoA y rhoGAP.
- El complejo se cristalizó con el GDP.AlF4- análogo del estado de transición a una resolución de 1,65 Å.
- Se realizó una comparación con un complejo de estado fundamental (Cdc42Hs.GMPPNP/rhoGAP).
Principales resultados:
- Se determinó la estructura cristalina del complejo RhoA-rhoGAP-GDP.AlF4.
- Se observó una rotación de 20 grados entre Rho y rhoGAP en el complejo de estado de transición en comparación con el complejo de estado fundamental.
- Un hallazgo clave es la contribución del residuo de rhoGAP Arg85 directamente en el sitio activo de RhoA en el estado de transición.
Conclusiones:
- El residuo de rhoGAP Arg85 probablemente estabiliza el estado de transición de la reacción de la GTPasa.
- RhoGAP parece estabilizar las regiones críticas de RhoA involucradas en la señalización de la hidrólisis de GTP.
- Esta visión estructural aclara el papel crucial de rhoGAP en la regulación de las vías de señalización mediadas por Rho.
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