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Activación del promotor de la polimerasa II: formación de complejo cerrado y apertura del sitio de inicio impulsado
1Department of Chemistry and Biochemistry, University of California, Los Angeles 90024.
Science (New York, N.Y.)
|January 24, 1992
Resumen
Los investigadores estudiaron la fusión del ADN durante la iniciación de la transcripción por la ARN polimerasa II de mamíferos. Descubrieron que el activador GAL4-VP16 estimula la formación de complejos cerrados, y la hidrólisis de ATP impulsa la fusión del ADN para formar el complejo abierto, lo que permite el inicio de la transcripción.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- La bioquímica es la bioquímica.
- Genética La genética.
Sus antecedentes:
- Las polimerasas de ARN bacteriano tienen pasos de iniciación bien definidos: unión al promotor, fusión del ADN y iniciación del ARNm.
- Comprender estos pasos en los sistemas de mamíferos es crucial para la investigación de la regulación génica.
Objetivo del estudio:
- Para investigar el proceso de fusión del ADN durante la iniciación de la transcripción por la ARN polimerasa II de mamíferos in vitro.
- Para aclarar las funciones de las proteínas activadoras y nucleósidos trifosfatos en este proceso.
Principales métodos:
- Utilizado permanganato de potasio como una sonda química para detectar la fusión del ADN.
- Se emplearon ensayos de transcripción in vitro con ARN polimerasa II de mamíferos purificada y el activador GAL4-VP16.
- Monitoreó la formación y la transición de complejos cerrados y abiertos.
Principales resultados:
- Se identificó la formación de complejos cerrados como un paso que limita la velocidad, estimulado significativamente por GAL4-VP16.
- Se encontró que la hidrólisis de trifosfato de adenosina (ATP) induce rápidamente la fusión del ADN dentro del complejo cerrado, formando el complejo abierto.
- La adición de nucleósidos trifosfatos promovió la translocación de la burbuja de ADN derretido, completando el inicio de la transcripción.
Conclusiones:
- El estudio proporciona una visión mecanicista detallada del paso de fusión del ADN de la iniciación de la transcripción por la ARN polimerasa II de mamíferos.
- GAL4-VP16 actúa como un estimulador crítico de la unión inicial del promotor.
- La hidrólisis de ATP es esencial para la transición de un complejo cerrado a un complejo abierto, un evento clave para que la transcripción continúe.
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