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La proteína patógena EspF(U) secuestra la polimerización de actina utilizando el mimetismo y la multivalencia.
Nathan A Sallee1, Gonzalo M Rivera, John E Dueber
1Graduate Program in Chemistry and Chemical Biology, University of California, San Francisco, 600 16th Street, San Francisco, California 94158, USA.
Nature
|July 25, 2008
Resumen
La Escherichia coli enterohemorrágica utiliza la proteína EspF(U) para desencadenar la formación de un pedestal de actina en las células huésped. Esta proteína imita de manera única un elemento interno N-WASP, no CDC42, para activar la polimerización de actina para la fijación bacteriana.
Área de la Ciencia:
- Microbiología Microbiología.
- Biología celular Biología celular.
- La bioquímica es la bioquímica.
Sus antecedentes:
- La Escherichia coli enterohemorrágica (EHEC, por sus siglas en inglés) utiliza pedestales de actina para la fijación intestinal.
- La inyección de la proteína bacteriana EspF(U) (TccP) en las células huésped induce la formación de un pedestal de actina.
- EspF(U) activa la proteína del síndrome de Wiskott-Aldrich (WASP) de la familia de nucleadores de actina, normalmente regulados por el CDC42.
Objetivo del estudio:
- Para aclarar el mecanismo por el cual EspF(U) activa N-WASP.
- Para identificar el motivo específico EspF(U) responsable de la interacción N-WASP.
- Para entender cómo EspF(U) explota la maquinaria de la célula huésped para la adhesión bacteriana.
Principales métodos:
- El análisis estructural de EspF(U) repite.
- Identificación del motivo de unión N-WASP dentro de la EspF (U).
- Ensayos bioquímicos para medir la polimerización de actina y la activación de N-WASP.
Principales resultados:
- Un motivo de 17 aminoácidos dentro de las repeticiones de EspF (U) es suficiente para la unión de N-WASP.
- EspF(U) imita un elemento autoinhibidor de N-WASP, no el activador natural CDC42.
- Múltiples repeticiones de EspF(U) mejoran la potencia de polimerización de actina mediante la coordinación de la activación de N-WASP.
Conclusiones:
- EHEC EspF(U) activa N-WASP al interrumpir su estado autoinhibido, ofreciendo un nuevo mecanismo de interacción patógeno-huésped.
- El patógeno ha diseñado una potente máquina de polimerización de actina utilizando simples y repetidos fragmentos autoinhibidores.
- Este mecanismo permite la activación selectiva de procesos celulares específicos, lo que facilita la colonización bacteriana.
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