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Monitoreo de la conformación proteica a lo largo de la trayectoria del plegamiento asistido por chaperonina

Shruti Sharma¹, Kausik Chakraborty, Barbara K Müller

¹Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany.

|April 9, 2008

Resumen

El sistema de acompañamiento bacteriano GroEL/GroES y el DnaK/DnaJ (Hsp70) aguas arriba ayudan al plegamiento de las proteínas. Este estudio revela cómo GroEL/GroES se despliega y luego vuelve a plegar las proteínas a través de cambios conformacionales, evitando el plegamiento incorrecto.

Área de la Ciencia:

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

Sus antecedentes:

El sistema de chaperonina GroEL/GroES es crucial para el plegamiento de las proteínas en las bacterias.
Las proteínas recién sintetizadas interactúan con las chaperonas aguas arriba como DnaK/DnaJ (Hsp70) antes de llegar a GroEL.

Objetivo del estudio:

Para monitorear las transiciones conformacionales de un sustrato modelo a lo largo de la vía DnaK/DnaJ a GroEL/GroES utilizando FRET de molécula única y conjunto.
Para aclarar el mecanismo por el cual GroEL/GroES facilita el plegamiento de proteínas.

Principales métodos:

La transferencia de energía de resonancia Förster de una sola molécula (smFRET)
El conjunto FRETET.
Monitoreo de cambios conformacionales de una proteína de sustrato modelo.

Principales resultados:

DnaK/DnaJ (Hsp70) estabiliza el plegamiento lento y los estados colapsados de las proteínas.
GroEL induce el despliegue y la expansión local, seguido de la movilización dependiente de ATP y la compactación parcial de los segmentos moderadamente hidrofóbicos.
La encapsulación de GroES conduce a la compactación completa y al plegamiento rápido, especialmente para las regiones más hidrofóbicas.

Conclusiones:

El sistema GroEL/GroES despliega y vuelve a desplegar activamente las proteínas, utilizando la liberación y compactación de la cadena segmentaria.
Este mecanismo evita el plegamiento incorrecto, especialmente para las proteínas que no se pliegan de manera eficiente a través del colapso hidrofóbico espontáneo.

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