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La chaperonina mitocondrial hsp60 es necesaria para su propio ensamblaje
M Y Cheng1, F U Hartl, A L Horwich
1Howard Hughes Medical Institute, Department of Human Genetics, Yale School of Medicine, New Haven, Connecticut 06510.
Nature
|November 29, 1990
Resumen
El ensamblaje de la proteína de choque térmico 60 (hsp60) en las mitocondrias requiere complejos preexistentes. Esto sugiere que la propia maquinaria de plegamiento de proteínas necesita orientación para la formación adecuada dentro de la célula.
Área de la Ciencia:
- Biología mitocondrial Biología mitocondrial
- El plegamiento de las proteínas.
- Las chaperonas moleculares son acompañantes.
Sus antecedentes:
- La proteína de choque térmico 60 (hsp60) es crucial para el plegamiento de proteínas dentro de las mitocondrias.
- Hsp60 funciona como una chaperonina, formando un complejo de 14 meros esencial para el ensamblaje de proteínas.
- El mecanismo de ensamblaje complejo hsp60 en sí mismo no estaba claro.
Objetivo del estudio:
- Para investigar el mecanismo de ensamblaje del complejo de la proteína de choque térmico 60 (hsp60).
- Para determinar si las subunidades hsp60 pueden autoensamblarse o requieren estructuras existentes.
Principales métodos:
- Estudió el ensamblaje de hsp60 en un mutante de levadura (mif4) defectuoso en hsp60.0.
- Se observó el ensamblaje de subunidades hsp60 de tipo salvaje tanto en células intactas como en mitocondrias aisladas.
- Se analizó la cinética de ensamblaje in vitro de las subunidades importadas hsp60.
Principales resultados:
- Las subunidades de hsp60 recién importadas no se autoensamblaron en la levadura mutante defectuosa de hsp60.
- Un complejo hsp60 funcional y preexistente es necesario para el ensamblaje de nuevos complejos de 14 meros.
- El ensamblaje in vitro de las subunidades hsp60 se produjo rápidamente (5-10 minutos de medio tiempo), lo que indica un proceso catalizado.
Conclusiones:
- El ensamblaje de los complejos funcionales de la proteína de choque térmico 60 (hsp60) no es un proceso de autoensamblaje espontáneo.
- Se requieren estructuras hsp60 existentes para facilitar el montaje de subunidades recién importadas.
- Esto desafía la noción de autoensamblaje simple como el mecanismo principal para el logro de la conformación de proteínas in vivo.
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