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Published on: August 26, 2012
CAP interactúa con la ARN polimerasa en solución en ausencia del ADN promotor
T Heyduk1, J C Lee, Y W Ebright
1Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, Galveston 77550.
Nature
|August 5, 1993
Resumen
La proteína activadora del gen catabólico (CAP) interactúa directamente con la ARN polimerasa. Esta interacción es crucial para la activación de la transcripción, como lo demuestran los mutantes CAP específicos que carecen de esta capacidad.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- La bioquímica es la bioquímica.
- Genética La genética.
Sus antecedentes:
- Las interacciones proteína-proteína son vitales para la activación de la transcripción.
- Se proponen interacciones de la proteína catabólica activadora del gen (CAP) con la ARN polimerasa, pero no se han demostrado directamente.
- Los mutantes CAP específicos defectuosos en la activación de la transcripción se asignan a un bucle superficial (aminoácidos 152-166).
Objetivo del estudio:
- Para investigar la interacción directa entre la CAP y la ARN polimerasa en solución.
- Para determinar si los mutantes CAP defectuosos en la activación de la transcripción conservan la capacidad de interactuar con la ARN polimerasa.
Principales métodos:
- Utilizó la polarización por fluorescencia, una técnica termodinámica rigurosa.
- Afinidad de unión medida (KD,app) entre el CAP de tipo silvestre y la ARN polimerasa.
- Se ha evaluado la unión de un mutante específico con defecto de activación de la transcripción, [Ala158]CAP.
Principales resultados:
- Se ha demostrado una interacción directa entre el CAP de tipo silvestre y la ARN polimerasa en solución (KD,app = 2,8 x 10(-7) M).
- [Ala158]CAP, un mutante específicamente defectuoso en la activación de la transcripción, no pudo interactuar con la ARN polimerasa.
- Esto sugiere que la interacción es esencial para la función de CAP en la activación de la transcripción.
Conclusiones:
- La interacción física directa entre la CAP y la ARN polimerasa es esencial para la activación de la transcripción.
- El bucle superficial (aminoácidos 152-166) de CAP es crítico para esta interacción y la subsiguiente regulación transcripcional.
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