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Mecanismo estructural de la activación de WASP por el efector enterohemorrágico de E. coli EspF (U)
Hui-Chun Cheng1, Brian M Skehan, Kenneth G Campellone
1Department of Biochemistry and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
Nature
|July 25, 2008
Resumen
La Escherichia coli enterohemorrágica (EHEC) secuestra la actina de la célula huésped inyectando la proteína EspF (U). Esta proteína se une y activa a los miembros de la familia de proteínas del síndrome de Wiskott-Aldrich (WASP), controlando el ensamblaje de actina durante la infección.
Área de la Ciencia:
- Microbiología Microbiología.
- Biología celular Biología celular.
- Biología Estructural Biología estructural.
Sus antecedentes:
- La Escherichia coli enterohemorrágica (EHEC) manipula el citoesqueleto de actina de la célula huésped durante la infección.
- La proteína efector bacteriana EspF(U) se inyecta en las células huésped para controlar la dinámica de la actina.
- Los miembros de la familia de proteínas del síndrome de Wiskott-Aldrich (WASP) son reguladores clave del ensamblaje de la actina.
Objetivo del estudio:
- Para aclarar el mecanismo por el cual la proteína EspF ((U) de EHEC activa las proteínas de la familia WASP.
- Determinar la base estructural de la interacción entre EspF{U} y WASP.
- Para entender cómo el EHEC secuestra efectivamente la maquinaria citoesquelética eucariota.
Principales métodos:
- Determinación de la estructura de la solución del dominio de unión de la GTPasa (GBD) -EspF(U) complejo.
- Ensayos de activación in vitro del WASP y del WASP neuronal (N).
- Ensayos basados en células para observar el ensamblaje de actina localizada.
Principales resultados:
- EspF(U) se une a la GBD autoinhibidora de las proteínas WASP, desplazándola del dominio VCA.
- Esta interacción activa potentemente WASP y N-WASP, induciendo el ensamblaje de actina localizada en las células.
- La estructura revela que EspF(U) imita las interacciones del dominio VCA, compitiendo por el sitio de unión GBD.
Conclusiones:
- EspF(U) activa WASP compitiendo directamente por el sitio de unión de GBD, un mecanismo distinto de los activadores eucariotas.
- La incompatibilidad estructural y la unión de alta afinidad permiten a EHEC secuestrar efectivamente la maquinaria de actina del huésped.
- La diversidad mecánica en la activación de WASP puede surgir de la naturaleza intrínsecamente no estructurada de sus dominios.
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