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Memoria de proteínas a través de plegamiento alterado mediado por chaperones intramoleculares

U P Shinde¹, J J Liu, M Inouye

¹Department of Biochemistry, Robert Wood Johnson Medical School-UMDNJ, Piscataway, New Jersey 08854, USA.

|October 23, 1997

Resumen

Los propéptidos de subtilisina actúan como chaperones intramoleculares, guiando el plegamiento del dominio de la proteasa. Una mutación en el chaperón crea un

Área de la Ciencia:

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

Sus antecedentes:

El propéptido de la subtilisina funciona como un acompañante intramolecular.
Este mecanismo se conserva en todas las proteínas procariotas y eucariotas, incluidas las prohormonas-convertasas.

Objetivo del estudio:

Para investigar el papel del propéptido subtilisin como un acompañante intramolecular.
Para determinar si las mutaciones en la chaperona pueden inducir conformaciones proteicas alteradas.

Principales métodos:

Mutagénesis dirigida al sitio del propéptido de la subtilisina (Ile(-48) a Val).
Análisis de la cinética de las enzimas, la secuencia de aminoácidos (secuenciación y espectrometría de masas), la afinidad de unión de chaperonas, la estructura secundaria, la termostabilidad y la especificidad del sustrato de la subtilisina E. salvaje y mutante.

Principales resultados:

Una chaperona intramolecular mutada indujo una conformación enzimáticamente activa "alterada" en la subtilisina E.
A pesar de las secuencias idénticas de aminoácidos, las subtilisinas alteradas y de tipo silvestre exhibieron distintas afinidades de unión a las chaperonas, estructuras secundarias, termostabilidad y especificidades del sustrato.
La subtilisina alterada mostró una afinidad 4,5 veces mayor por su chaperona congénita en comparación con las chaperonas no congénitas.

Conclusiones:

Un polipéptido idéntico puede plegarse en conformaciones distintas influenciadas por mutaciones en su chaperón intramolecular.
Este fenómeno, denominado "memoria de la proteína", sugiere que la vía de plegado puede dejar una huella duradera en la estructura y función de la proteína.
La memoria proteica puede tener implicaciones significativas para la comprensión de las enfermedades de plegamiento y mal plegamiento de las proteínas.

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