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Examining the Conformational Dynamics of Membrane Proteins in situ with Site-directed Fluorescence Labeling
Published on: May 29, 2011
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ClpX(P) genera fuerza mecánica para desplegar y translocar sus sustratos proteicos
Rodrigo A Maillard1, Gheorghe Chistol, Maya Sen
1Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, 94720, USA.
Cell
|May 3, 2011
Resumen
AAA(+) las despliegas como ClpX despliegan mecánicamente las proteínas usando ATP. La ClpX desfoldasa, especialmente con la ClpP peptidasa, desnaturaliza y transloca de manera eficiente los polipéptidos.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Molecular Biología Molecular
- Biología Estructural Biología estructural.
Sus antecedentes:
- Las AAA(+) desfoldasas son máquinas moleculares dependientes del ATP que se despliegan y translocan las proteínas.
- ClpX y ClpP forman un complejo (ClpXP) crucial para la degradación de las proteínas en E. coli.
Objetivo del estudio:
- Para observar directamente el despliegue mecánico de la proteína inducida por la fuerza por el despliegue de la ClpX.
- Investigar el papel de la hidrólisis de ATP y la interacción con ClpP en el proceso de despliegue y translocación.
Principales métodos:
- Espectroscopia de fuerza de una sola molécula para medir el despliegue de proteínas inducido por la fuerza.
- Observación de la translocación del polipéptido a través del poro central de ClpX.
- Análisis de la velocidad de translocación y el tamaño del paso.
Principales resultados:
- ClpX despliega las proteínas mecánicamente, con una velocidad de translocación dependiente de la fuerza, alcanzando un máximo de 80 aa/s de fuerza cercana a cero y cesando a ~20 pN.
- ClpX exhibe tamaños de paso de 1, 2 o 3 nm, lo que indica un paso fundamental de 1 nm y coordinación entre subunidades.
- La unión de ClpP reduce la probabilidad de deslizamiento de ClpX, mejorando la eficiencia del despliegue.
- El complejo ClpXP desentraña cooperativamente el GFP a través de un intermediario transitorio.
Conclusiones:
- ClpX utiliza la hidrólisis de ATP para generar fuerza mecánica para el despliegue y la translocación de proteínas.
- El complejo ClpXP demuestra una mayor eficiencia en el despliegue de proteínas en comparación con ClpX solo.
- Los hallazgos proporcionan información sobre el mecanismo del despliegue mecánico de proteínas por las AAA (((+) unfoldases.
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