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Función de la chaperonina: plegamiento por desdoblamiento forzado
M Shtilerman1, G H Lorimer, S W Englander
1The Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
Science (New York, N.Y.)
|April 30, 1999
Resumen
El sistema de chaperonina GroEL despliega parcialmente las proteínas mal plegadas en cuestión de segundos. Este proceso, que requiere la hidrólisis de ATP, ayuda a las proteínas a replegarse causando primero un despliegue parcial.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Molecular Biología Molecular
- El plegamiento de las proteínas.
Sus antecedentes:
- Las proteínas mal plegadas pueden acumularse y causar disfunción celular.
- Las chaperoninas son máquinas moleculares que ayudan al plegamiento de las proteínas.
- El mecanismo exacto por el cual GroEL facilita el despliegue y repliegue de las proteínas no se entiende completamente.
Objetivo del estudio:
- Investigar la capacidad del sistema de chaperonina GroEL para inducir el despliegue en proteínas de sustrato mal plegadas.
- Para determinar la cinética y los requisitos de energía para el despliegue mediado por GroEL.
- Para aclarar el papel del despliegue parcial en el proceso general de plegamiento de proteínas facilitado por GroEL.
Principales métodos:
- Utilizó técnicas de intercambio de hidrógeno para monitorear los cambios de conformación de las proteínas.
- Estudió el sistema de chaperonina GroEL y sus proteínas de sustrato.
- Se analizaron los efectos de la unión del nucleósido trifosfato y la hidrólisis del trifosfato de adenosina en el proceso de despliegue.
Principales resultados:
- El despliegue inducido por GroEL de la proteína del sustrato es parcial y requiere el sistema completo de chaperonina.
- El despliegue se produce dentro de los 13 segundos de tiempo de giro del sistema.
- La unión del nucleósido trifosfato proporciona energía para eventos individuales que se desarrollan; las renovaciones múltiples dependen de la hidrólisis del trifosfato de adenosina.
- La liberación de proteínas de sustrato se produce en cada giro, independientemente del estado de replegado.
- La estructura de GroEL parece optimizada para generar fuerza mecánica para el despliegue.
Conclusiones:
- GroEL facilita el plegamiento de proteínas al inducir el despliegue parcial en proteínas bloqueadas y mal plegadas.
- El sistema de la chaperonina emplea un mecanismo de despliegue mecánico.
- La energía para el despliegue es suministrada por la hidrólisis de ATP, lo que permite ciclos iterativos de despliegue y liberación.
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