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Detection of the pH-dependent Activity of Escherichia coli Chaperone HdeB In Vitro and In Vivo
Published on: October 23, 2016
Identificación de regiones de unión de nucleótidos en las proteínas chaperoninas GroEL y GroES
J Martin1, S Geromanos, P Tempst
1Cellular Biochemistry and Biophysics Program, Memorial Sloan-Kettering Cancer Center, New York 10021.
Nature
|November 18, 1993
Resumen
El sistema de chaperonina GroEL-GroES facilita el plegamiento de las proteínas en E. coli. Este estudio revela que GroES también se une al ATP, que puede ser crucial para GroEL.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- Mecanismos de plegamiento de las proteínas.
- La bioquímica es la bioquímica.
Sus antecedentes:
- La chaperonina GroEL y su cofactor GroES son esenciales para el plegamiento de proteínas en Escherichia coli.
- Forman un complejo que se une a las proteínas desplegadas, facilitando su liberación para el plegamiento en la hidrólisis de ATP.
Objetivo del estudio:
- Para identificar dominios de unión de nucleótidos dentro de las subunidades GroEL y GroES.
- Para investigar el papel de la unión de nucleótidos en la maquinaria de plegado de proteínas GroEL-GroES.
Principales métodos:
- Mutagenesis dirigida al sitio y etiquetado de proteínas con azido-ATP.
- Pruebas de estabilidad de la proteasa para identificar dominios de unión de nucleótidos.
- Análisis de la afinidad de unión al ATP y la cooperatividad en GroES.
Principales resultados:
- Se identificó un dominio de unión de nucleótidos estable en la proteasa (residuos 153-531) en GroEL, con un enlace cruzado azido-ATP a Tyr 477.
- Se encontró que GroES se une al ATP cooperativamente con una afinidad comparable a GroEL.
- El etiquetado de azido-nucleótido de GroES se produjo en Tyr 71 en un dominio 6.5K estable, con la escisión en el residuo 32 evitada cuando GroES se une a GroEL.
Conclusiones:
- Las subunidades GroEL contienen un dominio específico de unión de nucleótidos crucial para su función.
- GroES también se une al ATP, lo que sugiere un papel más complejo más allá de ser un simple membrano.
- La unión de ATP a GroES puede preparar el anillo de GroEL para una unión eficiente de ATP e hidrólisis, optimizando la liberación y el plegamiento de la proteína del sustrato.
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