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La estructura cristalina de la proteína DsbA es necesaria para la formación de enlaces disulfuro in vivo

J L Martin¹, J C Bardwell, J Kuriyan

¹Rockefeller University, New York, New York.

|September 30, 1993

Resumen

La proteína bacteriana DsbA acelera el plegamiento de las proteínas mediante la oxidación de los residuos de cisteína. Su estructura cristalina revela una disposición de dominio única, lo que sugiere que se une a proteínas desplegadas antes de la formación de enlaces disulfuro.

Área de la Ciencia:

La bioquímica es la bioquímica.
Biología Estructural Biología estructural.
Biología Molecular Biología Molecular

Sus antecedentes:

El plegamiento de las proteínas in vitro puede ser lento, especialmente para las proteínas con enlaces disulfuro, debido a la oxidación y el emparejamiento de la cisteína que limitan la velocidad.
La proteína bacteriana DsbA (enlace disulfuro A) acelera significativamente el plegamiento de las proteínas disulfuro-enlazadas en Escherichia coli.
El mecanismo preciso por el cual DsbA mejora las tasas de plegado sigue siendo incompletamente entendido.

Objetivo del estudio:

Para aclarar la base estructural para la mejora de la velocidad de plegamiento de proteínas por DsbA.
Comprender el mecanismo de acción del DsbA para facilitar la formación de enlaces disulfuro.

Principales métodos:

Se utilizó la cristalografía de rayos X para determinar la estructura tridimensional del DsbA. oxidado.
Se realizó una comparación estructural con otras proteínas redox, como la tioredoxina.

Principales resultados:

La estructura cristalina del DsbA oxidado revela un pliegue similar al de la proteína redox tioredoxina.
Una diferencia estructural clave es un dominio adicional en DsbA que cubre el sitio activo similar a la tioredoxina.
El sitio activo del enlace disulfuro se encuentra en una interfaz de dominio, rodeado de ranuras y cadenas laterales hidrofóbicas expuestas.

Conclusiones:

La estructura de DsbA sugiere un mecanismo que implica la unión a cadenas de polipéptidos parcialmente plegados.
La disposición única del dominio facilita la oxidación de los residuos de cisteína y la formación de enlaces disulfuro.
Esta visión estructural proporciona una base para comprender el papel de DsbA en la aceleración del plegamiento de las proteínas.

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