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La activación alosterica inducida por pequeñas moléculas del dominio de la proteasa cisteína RTX del Vibrio cholerae
Patrick J Lupardus1, Aimee Shen, Matthew Bogyo
1Department of Molecular and Cellular Physiology and Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
Science (New York, N.Y.)
|October 11, 2008
Resumen
La toxina RTX de Vibrio cholerae utiliza inositol hexaquisfosfato (InsP6) para activar su dominio de proteasa. La unión de InsP6 desencadena un interruptor alostérico, liberando los dominios efectores de la toxina.
Área de la Ciencia:
- Microbiología Microbiología.
- Biología Estructural Biología estructural.
- La bioquímica es la bioquímica.
Sus antecedentes:
- El Vibrio cholerae RTX es una toxina que altera la actina.
- La actividad de la toxina depende del autoprocesamiento por su dominio de proteasa cisteína (CPD).
Objetivo del estudio:
- Para aclarar las bases estructurales y mecánicas de la activación RTX CPD por InsP6.6.
- Para entender cómo la unión a InsP6 desencadena el procesamiento automático de toxinas.
Principales métodos:
- Cristalografía de rayos X para determinar la estructura del complejo RTX CPD-InsP6 a una resolución de 2.1 angstroms.
- Mutagénesis dirigida al sitio de la CPD.
- Análisis bioquímicos y cinéticos.
Principales resultados:
- Se determinó la estructura de 2.1 angstroms del RTX CPD en complejo con InsP6.
- InsP6 se une a una hendidura básica conservada, distante del sitio activo.
- Los datos de mutagenesis y cinética revelaron que la unión a InsP6 induce un interruptor alostérico.
Conclusiones:
- La unión de InsP6 a una hendidura distal activa alostericamente el RTX CPD.
- Este mecanismo de activación conduce al procesamiento automático y a la liberación de los dominios efectores.
- Los hallazgos proporcionan información sobre la regulación de la toxina bacteriana por los metabolitos de las células huésped.
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