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Mecanismo de acción de GroEL: liberación productiva de polipéptido desde una posición secuestrada bajo GroES

J S Weissman¹, C M Hohl, O Kovalenko

¹Department of Genetics, Yale School of Medicine New Haven, Connecticut 06510, USA.

|November 17, 1995

Resumen

El sistema de chaperonina GroEL-GroES ayuda al plegamiento de las proteínas a través de un mecanismo de dos pasos. GroES secuestra proteínas, y la hidrólisis de ATP impulsa su liberación y plegamiento productivo.

Área de la Ciencia:

Biología Molecular Biología Molecular
La bioquímica es la bioquímica.
El plegamiento de las proteínas.

Sus antecedentes:

La chaperonina GroEL, junto con la cochaperonina GroES y ATP, facilita el plegamiento de las proteínas in vivo.
GroEL es una estructura de doble anillo; GroES se une asimétricamente a un anillo GroEL.

Objetivo del estudio:

Para aclarar el mecanismo del plegamiento de proteínas mediado por GroEL-GroES.
Para investigar la dinámica de unión y liberación de polipéptidos dentro del complejo GroEL.

Principales métodos:

Estudios de enlaces cruzados para identificar sitios de unión de polipéptidos.
Experimentos de rotación única con transcarbamilase de ornitina.
Análisis de la formación y disociación del complejo GroEL-GroES.

Principales resultados:

La unión polipeptídica ocurre en el anillo GroEL no ocupado por GroES (complejo trans).
El GroES liberado puede volver a unirse al anillo GroEL que contiene polipéptido (complejo cis).
Los polipéptidos están protegidos en los complejos cis con ADP y productivamente liberados de los complejos cis, no trans.

Conclusiones:

Se propone un mecanismo de dos pasos para el plegado mediado por GroEL.
Paso 1: GroES desplaza y secuestra el polipéptido dentro de la cavidad GroEL.
Paso 2: La hidrólisis de ATP desencadena la liberación de GroES y la liberación de polipéptido productivo.

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