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La inhibición covalente revelada por la estructura cristalina del complejo caspase-8/p35
1Department of Biochemistry, Weill Medical College of Cornell University, New York, New York, 10021 USA
Nature
|March 22, 2001
Resumen
La proteína p35 del baculovirus previene la apoptosis al inhibir las caspasas. Los estudios estructurales y bioquímicos revelan un nuevo mecanismo en el que p35 forma un enlace covalente, bloqueando la actividad de la caspasa y proporcionando una inhibición de proteasa de amplio espectro.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- La bioquímica es la bioquímica.
- Biología Estructural Biología estructural.
Sus antecedentes:
- La apoptosis es un proceso regulado vital para el desarrollo de organismos multicelulares y la homeostasis.
- La proteína p35 del baculovirus es un conocido inhibidor de la apoptosis a través de la inhibición de la caspasa de amplio espectro.
Objetivo del estudio:
- Para dilucidar el mecanismo molecular de la inhibición de la caspasa mediada por p35.
- Para determinar la estructura cristalina de p35 en complejo con la caspasa-8.8 humana.
Principales métodos:
- Cristalografía de rayos X para obtener la estructura de 3,0 Å del complejo p35-caspasa-8.
- Análisis bioquímicos y estudios de mutagénesis para validar los hallazgos estructurales.
Principales resultados:
- La estructura reveló un enlace tioester covalente entre p35 y el sitio activo de la caspasa-8.
- La hendidura induce cambios conformacionales en p35, reposicionando su extremo N para bloquear el sitio activo.
- Las mutaciones en el extremo N de p35 abrogaron la actividad inhibidora, confirmando su papel.
Conclusiones:
- p35 emplea un nuevo mecanismo de inhibición de la caspasa que involucra enlaces covalentes y cambios conformacionales.
- El extremo N de p35 es crítico para estabilizar la inhibición y prevenir la hidrólisis intermedia.
- Los contactos conservados fuera del sitio activo contribuyen a la actividad inhibidora de amplio espectro de p35.
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