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Arquitectura molecular y ensamblaje de la maquinaria de ligasa ubiquitina DDB1-CUL4A

Stephane Angers¹, Ti Li, Xianhua Yi

¹Howard Hughes Medical Institute, University of Washington, School of Medicine, Box 357280, Seattle, Washington 98195, USA.

|September 12, 2006

Resumen

La ligasa de ubiquitina DDB1-CUL4A-ROC1 E3 utiliza un mecanismo estructural único para el reclutamiento de sustratos. Las nuevas proteínas de repetición WD40 se unen a DDB1, lo que permite la ubiquitinación de proteínas versátiles para la reparación del ADN y las vías de infección viral.

Área de la Ciencia:

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

Sus antecedentes:

La ubiquitinación de proteínas es una modificación post-traducional crítica que regula los procesos celulares.
Los complejos Cullin-RING, particularmente DDB1-CUL4A-ROC1, son las ligasas ubiquitinas E3 clave involucradas en la reparación, replicación y transcripción del ADN.
El mecanismo de reclutamiento del sustrato para DDB1-CUL4A-ROC1 permaneció en gran parte sin definir.

Objetivo del estudio:

Para dilucidar el ensamblaje estructural y el mecanismo de reclutamiento de sustratos de la DDB1-CUL4A-ROC1 E3 ubiquitin ligasa.
Para identificar los componentes responsables de la presentación del sustrato en el complejo DDB1-CUL4A-ROC1.

Principales métodos:

Análisis cristalográfico del complejo DDB1-CUL4A-ROC1 humano.
Purificación de afinidad en tándem de los complejos DDB1 y CUL4A.
Análisis de espectrometría de masas para identificar las proteínas que interactúan.

Principales resultados:

Los datos estructurales revelaron que DDB1 utiliza un dominio de beta-hélice para la unión de culina y una doble-beta-hélice separada para la presentación del sustrato.
Identificación de una nueva familia de proteínas de repetición WD40 que se unen directamente al dominio de doble hélice DDB1.
Estas proteínas de repetición WD40 funcionan como el módulo de reclutamiento de sustrato para la ligasa DDB1-CUL4A-ROC1 E3.

Conclusiones:

El estudio revela la base estructural para el ensamblaje DDB1-CUL4A-ROC1 y su versátil orientación al sustrato.
Las proteínas de repetición WD40 son componentes esenciales que median la especificidad del sustrato para esta familia de ligasas E3 de cullin-RING.
Comprender este mecanismo proporciona información sobre la reparación del ADN y el secuestro viral de la maquinaria celular.

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