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La unión multivalente de proteínas de sustrato no nativas por la chaperonina GroEL
G W Farr1, K Furtak, M B Rowland
1Howard Hughes Medical Institute and Department of Genetics, Yale School of Medicine, New Haven, Connecticut 06510, USA.
Cell
|March 18, 2000
Resumen
La chaperonina GroEL requiere al menos tres sitios de unión para proteínas estrictas como Rubisco. Las proteínas menos estrictas, como la rodanesa, se unen a menos sitios, mostrando GroEL.
Área de la Ciencia:
- Las Chaperonas Moleculares son las Chaperonas Moleculares.
- El plegamiento de las proteínas.
- La bioquímica es la bioquímica.
Sus antecedentes:
- La chaperonina GroEL facilita el plegamiento de las proteínas al unirse a sustratos no nativos.
- El mecanismo de GroEL involucra la unión de ATP y la interacción de GroES con la cochaperonina.
- El número de dominios apical GroEL involucrados en la unión al sustrato sigue sin estar claro.
Objetivo del estudio:
- Para investigar la estequiometría de la unión de proteínas no nativas a los dominios apicales GroEL.
- Determinar el número y la disposición mínimos de dominios de enlace eficientes requeridos para la interacción del sustrato.
Principales métodos:
- Utilizó anillos GroEL de ingeniería artificial con combinaciones de dominios apicales mutantes de tipo salvaje y de unión defectuosa.
- Se evaluó la formación de complejos binarios con proteínas de sustrato estrictas (malato deshidrogenasa, Rubisco) y menos estrictas (rodanesa).
- Se empleó el enlace cruzado oxidativo para confirmar físicamente la unión multivalente de Rubisco.
Principales resultados:
- Un mínimo de tres dominios apicales de tipo silvestre consecutivos eran necesarios para la unión eficiente de sustratos rigurosos.
- Un sustrato menos estricto, el rhodanese, requería solo dos dominios de unión, independientemente de su disposición.
- La evidencia directa de la unión de Rubisco multivalente a GroEL se obtuvo a través de enlaces cruzados.
Conclusiones:
- La unión al sustrato GroEL es multivalente, con proteínas estrictas que requieren múltiples sitios de interacción.
- El número de dominios de unión requeridos se correlaciona con la rigidez del sustrato.
- Este estudio aclara los aspectos cuantitativos del reconocimiento del sustrato por el sistema de chaperonina GroEL.
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