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Comunicación entre sitios distantes en la ARN polimerasa II a través de factores de ubicuidad y la polimerasa CTD
Baggavalli P Somesh1, Stefan Sigurdsson, Hideaki Saeki
1Mechanisms of Transcription Laboratory, Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms, UK.
Cell
|April 10, 2007
Resumen
La detención de la transcripción causa la ubicuidad de la ARN polimerasa II (RNAPII). Un mecanismo de modificación acoplado que involucra un dímer Rsp5 y Ubc5 explica la ubicuidad de RNAPII durante el alargamiento y la reparación del ADN.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- La bioquímica es la bioquímica.
- Genética La genética.
Sus antecedentes:
- La ubiquitación es una modificación post-traducional clave que regula la función de las proteínas.
- La ARN polimerasa II (RNAPII) es la enzima central para la transcripción génica.
- La ubicuidad del RNAPII está relacionada con la regulación de la transcripción y la respuesta al daño del ADN.
Objetivo del estudio:
- Para mapear los sitios de ubicuidad en el ARNPII de la levadura.
- Para dilucidar el mecanismo y la especificidad de la ubiquitación de RNAPII.
- Comprender el papel de la ubicuidad en el alargamiento de la transcripción y la respuesta al daño del ADN.
Principales métodos:
- Mutagénesis dirigida al sitio para identificar sitios de ubicuidad.
- Ensayos de ubicuidad in vitro e in vivo.
- Análisis de la estructura y las interacciones del dominio C-terminal (CTD) de RNAPII.
- Ensayos bioquímicos para estudiar las interacciones de la E3 ligasa (Rsp5) y la enzima conjugadora E2 (Ubc5).
Principales resultados:
- Se identificaron dos sitios de ubicuidad acoplados en el ARNPII de la levadura.
- Se demostró que un dímero Rsp5 en el RNAPII CTD media la ubicuidad.
- Se ha demostrado que Ubc5 (E2) conecta RNAPII y Rsp5 (E3) para su modificación.
- Se reveló que los sitios de ubicuidad distantes se comunican a través de interacciones CTD.
- Estableció el papel de la ubicuitación de RNAPII en la respuesta de alargamiento y daño al ADN.
Conclusiones:
- La ubicuidad de RNAPII es un proceso específico y acoplado regulado por un dimero Rsp5.
- El mecanismo implica la comunicación entre sitios distantes a través del plegado de CTD.
- Las enzimas E2 juegan un papel crítico en el reconocimiento del sustrato para la ubicuidad.
- Este estudio proporciona información sobre la regulación de la transcripción y las vías de reparación del ADN.
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