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La estructura cristalina de una familia romboide de las proteasas intramembrana
Yongcheng Wang1, Yingjiu Zhang, Ya Ha
1Department of Pharmacology, Yale School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, USA.
Nature
|October 20, 2006
Resumen
La estructura cristalina de Escherichia coli GlpG revela su sitio activo dentro de la membrana, lo que sugiere que la proteólisis intramembrana ocurre en un entorno hidrofóbico. Es probable que un mecanismo de bloqueo controle el acceso del sustrato a la enzima.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Estructural Biología estructural.
- Biología de la Membrana Biología de la Membrana.
Sus antecedentes:
- Escherichia coli GlpG es una proteína de membrana integral en la familia de las proteasas romboides.
- Las proteasas romboides cortan los dominios transmembranares de las proteínas de la membrana, similares a la proteasa del sitio-2 (S2P) y la gamma-secretasa.
Objetivo del estudio:
- Para determinar la estructura cristalina de alta resolución del dominio del núcleo GlpG.
- Para aclarar la base estructural para la proteólisis intramembrana por GlpG.
Principales métodos:
- Se utilizó cristalografía de rayos X para obtener la estructura cristalina de resolución 2.1 A del dominio central de GlpG.
- El análisis de la estructura de la proteína identificó residuos clave, moléculas de agua y vías de acceso al sustrato.
Principales resultados:
- La estructura GlpG revela seis segmentos transmembranares con una díada Ser-His catalítica ubicada en el interior de la proteína, debajo de la superficie de la membrana.
- Una abertura en forma de V proporciona acceso lateral a los sustratos, pero está parcialmente bloqueada por un bucle, lo que sugiere un mecanismo de cerradura.
- El sitio activo está posicionado dentro de la bicapa hidrofóbica de la membrana, lo que indica que la escisión del enlace péptido ocurre en este entorno.
Conclusiones:
- La proteólisis intramembrana por GlpG ocurre dentro de la bicapa hidrofóbica de la membrana.
- Es probable que un nuevo mecanismo de bloqueo regule el acceso del sustrato al sitio activo de GlpG.
- Las ideas estructurales avanzan en la comprensión de la función de la proteasa romboide y la proteólisis intramembrana.
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